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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. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Numerical Observation of a Tubular Phase in Anisotropic Membranes

    SciTech Connect

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

    1997-08-01

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

  10. 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.

  11. 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

  12. 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%.

  13. 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.

  14. 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.

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

    PubMed

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

    2015-01-01

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

  16. 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.

  17. 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.

  18. 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.

  19. 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

  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. 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.

  2. 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

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

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

    PubMed

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

    2002-07-01

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

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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

  16. 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 ...

  17. 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

  18. 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

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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.

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

    PubMed Central

    2013-01-01

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

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. Tubular Coupling

    NASA Technical Reports Server (NTRS)

    Rosenbaum, Bernard J. (Inventor)

    2000-01-01

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

  17. 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.

  18. 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

  19. Renal Tubular Acidosis

    MedlinePlus

    ... Old Feeding Your 1- to 2-Year-Old Renal Tubular Acidosis KidsHealth > For Parents > Renal Tubular Acidosis Print A A A What's in ... Causes Symptoms Diagnosis Treatment en español Acidosis tubular renal Each time our internal organs do something, such ...

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

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

    PubMed

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

    2013-01-01

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

  6. 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.

  7. 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

  8. 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.

  9. 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/ ...

  10. 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 ...

  11. 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.

  12. 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.

  13. [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.

  14. 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.

  15. 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.

  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. 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

  19. [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.

  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. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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…

  2. 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.

  3. 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.

  4. 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.

  5. A Simple Tubular Reactor Experiment.

    ERIC Educational Resources Information Center

    Hudgins, Robert R.; Cayrol, Bertrand

    1981-01-01

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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. How some proteins tubulate membranes

    NASA Astrophysics Data System (ADS)

    Bassereau, Patricia

    2009-03-01

    Endocytosis, exocytosis, membrane transport between intracellular compartments, virus or toxin entry or exit out of the cell, all imply to deform membrane. Membrane deformation mechanisms of cell membranes by proteins are currently actively studied. Giant vesicles (GUV) are interesting model membrane systems because they are composed of a very limited number of components compared to cellular membranes. The deformations induced by the interaction with a specific protein or any other additional components to the system, can then be directly monitored and the deformation mechanism eventually understood. In this talk, we will focus on different tubular structures induced by proteins. We will show that the B-subunits of Shiga toxin or Cholera Toxin, binding to their lipid receptors, Gb3 or GM1 respectively, incorporated in GUV membrane, induce negative membrane curvature and form tubular invaginations, in absence of any other cellular machinery. Tubular structures can also be obtained when molecular motors walking along microtubules exert a pulling force on the membrane of GUV. The helicoidal assembly of dynamin, a protein involved in vivo in membrane fission can also produce tubular structures. This assembly has been reconstituted around membrane nanotubes of controlled diameter; we will show that the initial tube diameter strongly influences dynamin polymerisation. In each case, a physical framework for understanding deformation mechanism will be presented

  18. 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.

  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. 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.

  2. Genetics Home Reference: tubular aggregate myopathy

    MedlinePlus

    ... Krahn M, Eymard B, Bartoli M, Laporte J. Constitutive activation of the calcium sensor STIM1 causes tubular- ... ORAI1 cause tubular aggregate myopathy with hypocalcemia via constitutive activation of store-operated Ca²⁺ channels. Hum Mol ...

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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...

  14. 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

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. Tubular system volume changes in twitch fibres from toad and rat skeletal muscle assessed by confocal microscopy

    PubMed Central

    Launikonis, Bradley S; Stephenson, D George

    2002-01-01

    The volume of the extracellular compartment (tubular system) within intact muscle fibres from cane toad and rat was measured under various conditions using confocal microscopy. Under physiological conditions at rest, the fractional volume of the tubular system (t-sysVol) was 1.38 ± 0.09 % (n = 17), 1.41 ± 0.09 % (n = 12) and 0.83 ± 0.07 % (n = 12) of the total fibre volume in the twitch fibres from toad iliofibularis muscle, rat extensor digitorum longus muscle and rat soleus muscle, respectively. In toad muscle fibres, the t-sysVol decreased by 30 % when the tubular system was fully depolarized and decreased by 15 % when membrane cholesterol was depleted from the tubular system with methyl-β-cyclodextrin but did not change as the sarcomere length was changed from 1.93 to 3.30 μm. There was also an increase by 30 % and a decrease by 25 % in t-sysVol when toad fibres were equilibrated in solutions that were 2.5-fold hypertonic and 50 % hypotonic, respectively. When the changes in total fibre volume were taken into consideration, the t-sysVol expressed as a percentage of the isotonic fibre volume did actually decrease as tonicity increased, revealing that the tubular system in intact fibres cannot be compressed below 0.9 % of the isotonic fibre volume. The results can be explained in terms of forces acting at the level of the tubular wall. These observations have important physiological implications showing that the tubular system is a dynamic membrane structure capable of changing its volume in response to the membrane potential, cholesterol depletion and osmotic stress but not when the sarcomere length is changed in resting muscle. PMID:11790823

  1. Tubular system volume changes in twitch fibres from toad and rat skeletal muscle assessed by confocal microscopy.

    PubMed

    Launikonis, Bradley S; Stephenson, D George

    2002-01-15

    The volume of the extracellular compartment (tubular system) within intact muscle fibres from cane toad and rat was measured under various conditions using confocal microscopy. Under physiological conditions at rest, the fractional volume of the tubular system (t-sys(Vol)) was 1.38 +/- 0.09 % (n = 17), 1.41 +/- 0.09 % (n = 12) and 0.83 +/- 0.07 % (n = 12) of the total fibre volume in the twitch fibres from toad iliofibularis muscle, rat extensor digitorum longus muscle and rat soleus muscle, respectively. In toad muscle fibres, the t-sys(Vol) decreased by 30 % when the tubular system was fully depolarized and decreased by 15 % when membrane cholesterol was depleted from the tubular system with methyl-beta-cyclodextrin but did not change as the sarcomere length was changed from 1.93 to 3.30 microm. There was also an increase by 30 % and a decrease by 25 % in t-sys(Vol) when toad fibres were equilibrated in solutions that were 2.5-fold hypertonic and 50 % hypotonic, respectively. When the changes in total fibre volume were taken into consideration, the t-sys(Vol) expressed as a percentage of the isotonic fibre volume did actually decrease as tonicity increased, revealing that the tubular system in intact fibres cannot be compressed below 0.9 % of the isotonic fibre volume. The results can be explained in terms of forces acting at the level of the tubular wall. These observations have important physiological implications showing that the tubular system is a dynamic membrane structure capable of changing its volume in response to the membrane potential, cholesterol depletion and osmotic stress but not when the sarcomere length is changed in resting muscle.

  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. 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

  9. 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..

  10. 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.

  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. 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

  13. 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

  14. 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.

  15. 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.

  16. 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...

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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)

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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

  15. 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.

  16. 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

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

    PubMed Central

    2012-01-01

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

  18. 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

  19. 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

  20. 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.

  1. 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

  2. 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).

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. Distal Renal Tubular Acidosis and Calcium Nephrolithiasis

    NASA Astrophysics Data System (ADS)

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

    2008-09-01

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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  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

    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.

  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

    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

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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.

  3. 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

  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. 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.

  7. 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

  8. 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.

  9. 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.

  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. 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.

  12. 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.

  13. 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.

  14. [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.

  15. 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

  16. Study on capillaries covalently bound with phospholipid vesicles for open-tubular capillary electrochromatography and application to on-line open-tubular capillary electrochromatography-mass spectrometry.

    PubMed

    Tiala, Heidi; Riekkola, Marja-Liisa; Wiedmer, Susanne K

    2013-12-01

    Phospholipid vesicles were covalently attached to iminoaldehyde-coated fused silica capillaries and applied to the separation of model steroids by open-tubular CEC (OT-CEC). The effects of reducing the formed Schiff's base with sodium borohydride and of the liposome composition on the stability of the coating were investigated. In addition, the studies were focused on the optimization of running conditions (pH values and composition of BGE solution) when CEC, using capillaries covalently bound with liposome dispersions, was coupled to MS. The effect of cholesterol in the liposome dispersion on the binding of model analytes was studied, using liposome dispersions comprising 80/20 mol% zwitterionic 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocholine (POPC) and the negatively charged phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS) and 40/40/20 mol% POPC/POPS/cholesterol. Cholesterol in liposomes (greatly) enhanced the stability of the capillaries by making the coatings more rigid, resulting in lower retention factors for all the studied model steroids. Although most of the studies were carried out by open tubular CEC-UV Vis, the applicability of the capillaries to on-line CEC-MS was demonstrated as well. On-line CEC-MS studies on model steroids proved the suitability of coated capillaries for analyte-lipid membrane interaction studies, and especially for such analytes that are difficult to detect by conventional on-line UV Vis.

  17. 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.

  18. 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

  19. 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.

  20. 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)

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. [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)

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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

  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. 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}.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. OXYGEN TRANSPORT CERAMIC MEMBRANES

    SciTech Connect

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2003-01-01

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

  7. 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

  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. 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

  11. 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.

  12. 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.

  13. Strength of Welded Joints in Tubular Members for Aircraft

    DTIC Science & Technology

    1930-02-06

    STRENGTH OF WELDED JOINTS IN TUBULAR MEMBERS FOR AIRCRAFT By H. L. WHITTEMORE and W. C. BRUEGGEMAN Bureau of Standards ——— - ..— .-.— .— .— —___ 107346->1...331 331 332 341 341 342 343 343 343 347 347 347 367 .— .— — ● REPORT ~0, 348 STRENGTH OF WELDED JOINTS IN TUBULAR MELMBERS FOR AIRCRAFT By H. L...airoraft welds has been publi~hed)lit ig beh%redthat euch tests made by a disinterested governmental laboratory should be of considerablemdueto the

  14. 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

  15. 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...

  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. 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.

  18. 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

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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.

  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. 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.

  9. 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.

  10. 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.

  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. 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.

  13. 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.

  14. 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.

  15. 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

  16. 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.

  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. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. Testing composite-to-metal tubular lap joints

    SciTech Connect

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

    1993-11-01

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

  4. Dynamic model of microalgal production in tubular photobioreactors.

    PubMed

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

    2012-12-01

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

  5. 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.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

    Beller, Daniel; Nelson, David

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

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Structural study of non-premixed tubular hydrocarbon flames

    SciTech Connect

    Hu, Shengteng; Pitz, Robert W.

    2009-01-15

    Tubular non-premixed flames are formed by a uniquely designed opposed tubular burner. Structural measurements of hydrocarbon flames are conducted using the laser-induced Raman scattering technique. Temperature and major species concentrations are recorded for flames produced by 30% CH{sub 4}/N{sub 2} and 15% C{sub 3}H{sub 8}/N{sub 2} burning against air. Numerical simulations of these flames with detailed chemistry show good agreement between the measured and simulated results. By comparing the numerical results of the tubular curved flames to those of the opposed-jet planar flames, it is shown that flame curvature towards the fuel stream strongly effects the temperature ({+-}80 K) of flames with low fuel Lewis number (15% H{sub 2}/N{sub 2}, Le{sub f} = 0.41). The effect of curvature on flames with high (15% C{sub 3}H{sub 8}/N{sub 2}, Le{sub f} = 1.51) and near-unity (30% CH{sub 4}/N{sub 2}, Le{sub f}{approx_equal}1) fuel Lewis numbers is much less. (author)

  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. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

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

    PubMed Central

    Delevoye, Cédric; Romao, Maryse; Owen, David J.; Raposo, Graça

    2016-01-01

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

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

    SciTech Connect

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

    2015-06-01

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

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

    PubMed Central

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

    2016-01-01

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

  5. Dynamic modeling of temperature change in outdoor operated tubular photobioreactors.

    PubMed

    Androga, Dominic Deo; Uyar, Basar; Koku, Harun; Eroglu, Inci

    2017-04-06

    In this study, a one-dimensional transient model was developed to analyze the temperature variation of tubular photobioreactors operated outdoors and the validity of the model was tested by comparing the predictions of the model with the experimental data. The model included the effects of convection and radiative heat exchange on the reactor temperature throughout the day. The temperatures in the reactors increased with increasing solar radiation and air temperatures, and the predicted reactor temperatures corresponded well to the measured experimental values. The heat transferred to the reactor was mainly through radiation: the radiative heat absorbed by the reactor medium, ground radiation, air radiation, and solar (direct and diffuse) radiation, while heat loss was mainly through the heat transfer to the cooling water and forced convection. The amount of heat transferred by reflected radiation and metabolic activities of the bacteria and pump work was negligible. Counter-current cooling was more effective in controlling reactor temperature than co-current cooling. The model developed identifies major heat transfer mechanisms in outdoor operated tubular photobioreactors, and accurately predicts temperature changes in these systems. This is useful in determining cooling duty under transient conditions and scaling up photobioreactors. The photobioreactor design and the thermal modeling were carried out and experimental results obtained for the case study of photofermentative hydrogen production by Rhodobacter capsulatus, but the approach is applicable to photobiological systems that are to be operated under outdoor conditions with significant cooling demands.

  6. Tubular dielectric elastomer actuator for active fluidic control

    NASA Astrophysics Data System (ADS)

    McCoul, David; Pei, Qibing

    2015-10-01

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

  7. Tubular aggregates of cyclic oligothiophenes. A theoretical study.

    PubMed

    Flores, Paola; Guadarrama, Patricia; Ramos, Estrella; Fomine, Serguei

    2008-05-01

    The geometries of neutral, mono-, and dioxidized tubular aggregates of cyclo[8]thiophenes containing up to 5 repeating units were fully optimized at the MPWB1K/3-21G* level of theory. Calculated interplane distances between macrocycles were found to be close to 3.1 A for neutral and charged aggregates. The binding energies between macrocycles in neutral intermediates were in the range of 40-45 kcal/mol, increasing for monocations and dropping strongly for dicationic species due to electrostatic repulsion between polarons. It was established that there exists a noticeable interaction between pi-orbitals of individual macrocycles in tubular aggregates as follows from decreasing of the band gap with a number of repeating units in aggregates and the polaron delocalization toward tube axes in oxidized species. A polaron pair is the most stable dicationic state for all studied molecules according to the calculations. A singlet polaron pair is more stable than a triplet one. The energy difference between singlet and triplet states is growing smaller with the size of the system, becoming zero for the pentamer corresponding to a completely dissociated bipolaron.

  8. Numerical investigation of cavitation performance on bulb tubular turbine

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  9. Tubular woven narrow fabrics for replacement of cruciate ligaments.

    PubMed

    Gloy, Yves-Simon; Loehrer, M; Lang, B; Rongen, L; Gries, T; Jockenhoevel, S

    2013-09-01

    The human knee is one of the most frequently injured joints. More than half of these injuries are related to a failure of the anterior cruciate ligament. Current treatments (allogeneic and autologous) bear several disadvantages which can be overcome through the use of synthetic structures. Within the scope of this paper the potential of tubular woven fabrics for the use as artificial ligaments has been evaluated. Twelve fabrics made of polyethylene terephthalate and polytetrafluoroethylene were produced using shuttle weaving technology. Mechanical and biological properties of the fabrics were assessed using static tensile testing and cytotoxicity assays. The results obtained within this study show that woven tubular fabrics can be potentially used as artificial ligament structures as they can provide the desired medical and mechanical properties for cruciate ligament replacements. Through the choice of material and weaving parameters the fabrics' tensile properties can imitate the stress-strain characteristic of the human cruciate ligament. Further assessments in terms of cyclic loading behavior and abrasion resistance of the material are needed to evaluate the success in long term implantation.

  10. Additive manufacturing of patient-specific tubular continuum manipulators

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  11. Nano-Tubular Cellulose for Bioprocess Technology Development

    PubMed Central

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

    2012-01-01

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

  12. Negative Stains Containing Trehalose: Application to Tubular and Filamentous Structures

    NASA Astrophysics Data System (ADS)

    Harris, J. Robin; Gerber, Max; Gebauer, Wolfgang; Wernicke, Wolfgang; Markl, Jürgen

    1996-02-01

    Several examples are presented that show the successful application of uranyl acetate and ammonium molybdate negative staining in the presence of trehalose for TEM studies of filamentous and tubular structures. The principal benefit to be gained from the inclusion of trehalose stems from the considerably reduced flattening of the large tubular structures and the greater orientational freedom of single molecules due to an increased depth of the negative stain in the presence of trehalose. Trehalose is likely to provide considerable protection to protein molecules and their assemblies during the drying of negatively stained specimens. Some reduction in the excessive density imparted by uranyl acetate around large assemblies is also achieved. Nevertheless, in the presence of 1% (w/v) trehalose, it is desirable to increase the concentration of negative stain to 5% (w/v) for ammonium molybdate and to 4% for uranyl acetate to produce satisfactory image contrast. In general, the ammonium molybdate-trehalose negative stain is more satisfactory than the uranyl acetate-trehalose combination, because of the greater electron beam sensitivity of the uranyl negative stain. Reassembled taxol-stabilized pig brain microtubules, together with collagen fibrils, sperm tails, helical filaments, and reassociated hemocyanin (KLH2), all from the giant keyhole limpet Megathura crenulata, have been studied by negative staining in the presence of trehalose. In all cases satisfactory TEM imaging conditions were readily obtained on the specimens, as long as regions of excessively deep stain were avoided.

  13. Impregnation of tubular self-assemblies into dextran hydrogels.

    PubMed

    Sun, Guoming; Chu, Chih-Chang

    2010-02-16

    Amine groups are the building units of proteins. The incorporation of amine groups into polyethylene glycol diacrylate (PEGDA) hydrogel through dextran-allyl isocyanate-ethylamine (Dex-AE) enhances sustained protein release by introducing effective interactions. To investigate such an interaction effect and to improve protein release, we impregnated self-assembled tubular structures from dextran-bromoethylamine (Dex-BH) and dextran-chloroacetic acid (Dex-CA) into Dex-AE/PEGDA hydrogel. The morphology data obtained from scanning electron microscopy (SEM) reveal that pure PEGDA hydrogel had no effect on the distribution of the self-assembled tubules; the introduction of Dex-AE brought about the dispersion of these tubules, and an increase in Dex-AE content led to more evenly distributed structures. Moreover, the implantation of the self-assembled tubules had no distinct effect on the swelling capacity of the hybrid self-assembly embedded hydrogels. The in vitro albumin release study was carried out in a pH 7.4 buffer solution; the results show that the implantation of the self-assembly into the hydrogels reduced the burst release and prolonged the protein release time. These findings demonstrate that the impregnation of tubular self-assembly into hydrogel makes the hybrid hydrogel an excellent protein delivery system.

  14. Tubular bamboo charcoal for anode in microbial fuel cells

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  15. Toward automated cochlear implant insertion using tubular manipulators

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    PubMed

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

    2005-06-01

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

  17. Nano-tubular cellulose for bioprocess technology development.

    PubMed

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

    2012-01-01

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

  18. Advances in tubular solid oxide fuel cell technology

    SciTech Connect

    Singhal, S.C.

    1996-12-31

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

  19. Intraductal tubular neoplasms of the pancreas: an overview.

    PubMed

    Chelliah, Adeline; Kalimuthu, Sangeetha; Chetty, Runjan

    2016-10-01

    Intraductal lesions of the pancreas are an uncommon but increasingly recognized group of entities mainly because of advances in imaging technology. In the past, precise categorization and understanding of true pancreatic intraduct neoplasms were hampered not only by their relative rarity but also because of the plethora of terminology and criteria used in nomenclature and diagnosis. Although significant progress has been made in the characterization of some of these lesions, as exemplified by intraductal papillary mucinous neoplasms, understanding of the rare intraductal tubular adenoma (ITA) and intraduct tubular carcinoma (ITC) continues to evolve. By definition, these are a group of intraductal, radiologically detectable neoplasms that can progress to or be associated with invasive adenocarcinoma and, as such, are precursor lesions to pancreatic ductal adenocarcinoma. Their often shared clinical and radiological features make precise histological diagnosis essential for appropriate management and optimal outcome. We provide an overview of these neoplasms and highlight recent developments in the understanding of ITA and ITC which have led to ITA being considered a variant of gastric-type intraductal papillary mucinous neoplasms and ITC being encompassed within the intraductal tubulopapillary neoplasm category. We also emphasize the distinguishing histological features to aid diagnosis of these rare lesions.

  20. Vibration dampener for dampening vibration of a tubular member

    DOEpatents

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

    1994-10-18

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

  1. Vibration dampener for dampening vibration of a tubular member

    DOEpatents

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

    1994-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed Central

    Ueda, Norishi

    2015-01-01

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

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

    PubMed

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

    2012-11-01

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

  6. Multilayer chitosan-based open tubular capillary anion exchange column with integrated monolithic capillary suppressor.

    PubMed

    Huang, Xiaojia; Foss, Frank W; Dasgupta, Purnendu K

    2011-11-30

    We describe a multilayered open tubular anion exchange column fabricated by alternately pumping solutions of chitosan and glutaraldehyde. The column is terminated in an integrally bonded monolithic suppressor cast around a mandrel of a tungsten wire, composed of an acrylic acid (AA)-ethylene dimethacrylate (EDMA) monolith that is made with sufficient porogen for the monolith to function as a membrane. For a 4.5m long 75 μm bore column coated with 24 successive layers of the condensation polymer (estimated to contain ~72 molecular layers) and coupled to 1cm length of a suppressor fabricated with 55-60% AA, effective separation of several common anions (F(-), Cl(-), NO(2)(-), Br(-), NO(3)(-), average number of theoretical plates ~12,000) and adequate suppression of 1 mM KOH used as eluent was observed at a flow rate of 800 nL min(-1) to obtain sub-picomol detection limits at an operating pressure of ~1 bar. The separation is not time efficient but the system can be meritorious in unique niche applications where a small form factor is desired and liquid volume and power consumption are more important than separation speed.

  7. Colocalization properties of elementary Ca(2+) release signals with structures specific to the contractile filaments and the tubular system of intact mouse skeletal muscle fibers.

    PubMed

    Georgiev, Tihomir; Zapiec, Bolek; Förderer, Moritz; Fink, Rainer H A; Vogel, Martin

    2015-12-01

    Ca(2+) regulates several important intracellular processes. We combined second harmonic generation (SHG) and two photon excited fluorescence microscopy (2PFM) to simultaneously record the SHG signal of the myosin filaments and localized elementary Ca(2+) release signals (LCSs). We found LCSs associated with Y-shaped structures of the myosin filament pattern (YMs), so called verniers, in intact mouse skeletal muscle fibers under hypertonic treatment. Ion channels crucial for the Ca(2+) regulation are located in the tubular system, a system that is important for Ca(2+) regulation and excitation-contraction coupling. We investigated the tubular system of intact, living mouse skeletal muscle fibers using 2PFM and the fluorescent Ca(2+) indicator Fluo-4 dissolved in the external solution or the membrane dye di-8-ANEPPS. We simultaneously measured the SHG signal from the myosin filaments of the skeletal muscle fibers. We found that at least a subset of the YMs observed in SHG images are closely juxtaposed with Y-shaped structures of the transverse tubules (YTs). The distances of corresponding YMs and YTs yield values between 1.3 μm and 4.1 μm including pixel uncertainty with a mean distance of 2.52±0.10 μm (S.E.M., n=41). Additionally, we observed that some of the linear-shaped areas in the tubular system are colocalized with linear-shaped areas in the SHG images.

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

    DOEpatents

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

    2006-11-28

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

  9. 78 FR 77420 - Certain Oil Country Tubular Goods From the Republic of Turkey: Preliminary Negative...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-23

    ... International Trade Administration Certain Oil Country Tubular Goods From the Republic of Turkey: Preliminary... tubular goods (OCTG) from the Republic of Turkey (Turkey). The period of investigation is January 1, 2012... Turkey and several other countries.\\1\\ The CVD investigation and the AD investigations cover the...

  10. Tubular Carcinoma of the Breast: Advantages and Limitations of Breast Tomosynthesis

    PubMed Central

    Rocha, Ana; Reis, Alcinda

    2016-01-01

    Tubular carcinoma of the breast is a rare variant of invasive ductal carcinoma. We report a case of 42-year-old asymptomatic female with a histopathological proven multifocal tubular carcinoma, studied by mammography, Tomosynthesis, Ultrasound, and Magnetic Resonance. Herein, we discuss the advantages and limitations of Tomosynthesis, an emerging imaging technique, in this particular case. PMID:28116205

  11. Rapid antibiotic efficacy screening with aluminum oxide nanoporous membrane filter-chip and optical detection system.

    PubMed

    Tsou, Pei-Hsiang; Sreenivasappa, Harini; Hong, Sungmin; Yasuike, Masayuki; Miyamoto, Hiroshi; Nakano, Keiyo; Misawa, Takeyuki; Kameoka, Jun

    2010-09-15

    We have developed a filter-chip and optical detection system for rapid antibiotic efficacy screening. The filter-chip consisted of a 1-mL reservoir and an anodic aluminum oxide (AAO) nanoporous membrane. Sample solution with liquid growth media, bacteria, and antibiotics was incubated in the reservoir for a specific period of time. The number of live bacteria on the surface of membrane was counted after the incubation with antibiotics and filtration. Using this biosensing system, we have demonstrated a 1-h antibiotic screening for patients' clinical samples, significantly faster than the conventional antibiotic susceptibility tests that typically take more than 24h. This rapid screening nature makes the filter-chip and detection system ideal for tailoring antibiotic treatment to individual patients by reducing the microbial antibiotic resistance, and improving the survival rate for patients suffering from postoperative infections.

  12. Proximal renal tubular acidosis mediated by mutations in NBCe1-A: unraveling the transporter's structure-functional properties

    PubMed Central

    Kurtz, Ira; Zhu, Quansheng

    2013-01-01

    NBCe1 belongs to the SLC4 family of base transporting membrane proteins that plays a significant role in renal, extrarenal, and systemic acid-base homeostasis. Recent progress has been made in characterizing the structure-function properties of NBCe1 (encoded by the SLC4A4 gene), and those factors that regulate its function. In the kidney, the NBCe1-A variant that is expressed on the basolateral membrane of proximal tubule is the key transporter responsible for overall transepithelial bicarbonate absorption in this nephron segment. NBCe1 mutations impair transepithelial bicarbonate absorption causing the syndrome of proximal renal tubular acidosis (pRTA). Studies of naturally occurring NBCe1 mutant proteins in heterologous expression systems have been very helpful in elucidation the structure-functional properties of the transporter. NBCe1 mutations are now known to cause pRTA by various mechanisms including the alteration of the transporter function (substrate ion interaction, electrogenicity), abnormal processing to the plasma membrane, and a perturbation in its structural properties. The elucidation of how NBCe1 mutations cause pRTA in addition to the recent studies which have provided further insight into the topology of the transporter have played an important role in uncovering its critically important structural-function properties. PMID:24391589

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

    PubMed

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

    2015-11-11

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

  14. Dysfunctional tubular endoplasmic reticulum constitutes a pathological feature of Alzheimer's disease.

    PubMed

    Sharoar, M G; Shi, Q; Ge, Y; He, W; Hu, X; Perry, G; Zhu, X; Yan, R

    2016-09-01

    Pathological features in Alzheimer's brains include mitochondrial dysfunction and dystrophic neurites (DNs) in areas surrounding amyloid plaques. Using a mouse model that overexpresses reticulon 3 (RTN3) and spontaneously develops age-dependent hippocampal DNs, here we report that DNs contain both RTN3 and REEPs, topologically similar proteins that can shape tubular endoplasmic reticulum (ER). Importantly, ultrastructural examinations of such DNs revealed gradual accumulation of tubular ER in axonal termini, and such abnormal tubular ER inclusion is found in areas surrounding amyloid plaques in biopsy samples from Alzheimer's disease (AD) brains. Functionally, abnormally clustered tubular ER induces enhanced mitochondrial fission in the early stages of DN formation and eventual mitochondrial degeneration at later stages. Furthermore, such DNs are abrogated when RTN3 is ablated in aging and AD mouse models. Hence, abnormally clustered tubular ER can be pathogenic in brain regions: disrupting mitochondrial integrity, inducing DNs formation and impairing cognitive function in AD and aging brains.

  15. MDM2 prevents spontaneous tubular epithelial cell death and acute kidney injury

    PubMed Central

    Thomasova, Dana; Ebrahim, Martrez; Fleckinger, Kristina; Li, Moying; Molnar, Jakob; Popper, Bastian; Liapis, Helen; Kotb, Ahmed M; Siegerist, Florian; Endlich, Nicole; Anders, Hans-Joachim

    2016-01-01

    Murine double minute-2 (MDM2) is an E3-ubiquitin ligase and the main negative regulator of tumor suppressor gene p53. MDM2 has also a non-redundant function as a modulator of NF-kB signaling. As such it promotes proliferation and inflammation. MDM2 is highly expressed in the unchallenged tubular epithelial cells and we hypothesized that MDM2 is necessary for their survival and homeostasis. MDM2 knockdown by siRNA or by genetic depletion resulted in demise of tubular cells in vitro. This phenotype was completely rescued by concomitant knockdown of p53, thus suggesting p53 dependency. In vivo experiments in the zebrafish model demonstrated that the tubulus cells of the larvae undergo cell death after the knockdown of mdm2. Doxycycline-induced deletion of MDM2 in tubular cell-specific MDM2-knockout mice Pax8rtTa-cre; MDM2f/f caused acute kidney injury with increased plasma creatinine and blood urea nitrogen and sharp decline of glomerular filtration rate. Histological analysis showed massive swelling of renal tubular cells and later their loss and extensive tubular dilation, markedly in proximal tubules. Ultrastructural changes of tubular epithelial cells included swelling of the cytoplasm and mitochondria with the loss of cristae and their transformation in the vacuoles. The pathological phenotype of the tubular cell-specific MDM2-knockout mouse model was completely rescued by co-deletion of p53. Tubular epithelium compensates only partially for the cell loss caused by MDM2 depletion by proliferation of surviving tubular cells, with incomplete MDM2 deletion, but rather mesenchymal healing occurs. We conclude that MDM2 is a non-redundant survival factor for proximal tubular cells by protecting them from spontaneous p53 overexpression-related cell death. PMID:27882940

  16. Hierarchy in inorganic membranes.

    PubMed

    Caro, Juergen

    2016-06-13

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

  17. Topological location and structural importance of the NBCe1-A residues mutated in proximal renal tubular acidosis.

    PubMed

    Zhu, Quansheng; Kao, Liyo; Azimov, Rustam; Newman, Debra; Liu, Weixin; Pushkin, Alexander; Abuladze, Natalia; Kurtz, Ira

    2010-04-30

    NBCe1-A electrogenically cotransports Na(+) and HCO(3)(-) across the basolateral membrane of renal proximal tubule cells. Eight missense mutations and 3 nonsense mutations in NBCe1-A cause severe proximal renal tubular acidosis (pRTA). In this study, the topologic properties and structural importance of the 8 endogenous residues mutated in pRTA and the in situ topology of NBCe1-A were examined by the substituted cysteine accessibility method. Of the 55 analyzed individually introduced cysteines, 8 were labeled with both membrane permeant (biotin maleimide (BM)) and impermeant (2-((5(6)-tetramethylrhodamine)carboxylamino)ethyl methanethiosulfonate (MTS-TAMRA)) sulfhydryl reagents, 4 with only BM, and 3 with only MTS-TAMRA. The location of the labeled and unlabeled introduced cysteines clearly indicates that the transmembrane region of NBCe1-A contains 14 transmembrane segments (TMs). In this in situ based NBCe1-A topology, residues mutated in pRTA (pRTA residues) are assigned as: Ser(427), TM1; Thr(485) and Gly(486), TM3; Arg(510) and Leu(522), TM4; Ala(799), TM10; and Arg(881), TM12. Substitution of pRTA residues with cysteines impaired the membrane trafficking of R510C and R881C, the remaining membrane-processed constructs had various impaired transport function. Surprisingly, none of the membrane-processed constructs was accessible to labeling with BM and MTS-TAMRA, nor were they functionally sensitive to the inhibition by (2-aminoethyl)methanethiosulfonate. Functional analysis of Thr(485) with different amino acid substitutions indicated it resides in a unique region important for NBCe1-A function. Our findings demonstrate that the pRTA residues in NBCe1-A are buried in the protein complex/lipid bilayer where they perform important structural roles.

  18. Topological Location and Structural Importance of the NBCe1-A Residues Mutated in Proximal Renal Tubular Acidosis*

    PubMed Central

    Zhu, Quansheng; Kao, Liyo; Azimov, Rustam; Newman, Debra; Liu, Weixin; Pushkin, Alexander; Abuladze, Natalia; Kurtz, Ira

    2010-01-01

    NBCe1-A electrogenically cotransports Na+ and HCO3− across the basolateral membrane of renal proximal tubule cells. Eight missense mutations and 3 nonsense mutations in NBCe1-A cause severe proximal renal tubular acidosis (pRTA). In this study, the topologic properties and structural importance of the 8 endogenous residues mutated in pRTA and the in situ topology of NBCe1-A were examined by the substituted cysteine accessibility method. Of the 55 analyzed individually introduced cysteines, 8 were labeled with both membrane permeant (biotin maleimide (BM)) and impermeant (2-((5(6)-tetramethylrhodamine)carboxylamino)ethyl methanethiosulfonate (MTS-TAMRA)) sulfhydryl reagents, 4 with only BM, and 3 with only MTS-TAMRA. The location of the labeled and unlabeled introduced cysteines clearly indicates that the transmembrane region of NBCe1-A contains 14 transmembrane segments (TMs). In this in situ based NBCe1-A topology, residues mutated in pRTA (pRTA residues) are assigned as: Ser427, TM1; Thr485 and Gly486, TM3; Arg510 and Leu522, TM4; Ala799, TM10; and Arg881, TM12. Substitution of pRTA residues with cysteines impaired the membrane trafficking of R510C and R881C, the remaining membrane-processed constructs had various impaired transport function. Surprisingly, none of the membrane-processed constructs was accessible to labeling with BM and MTS-TAMRA, nor were they functionally sensitive to the inhibition by (2-aminoethyl)methanethiosulfonate. Functional analysis of Thr485 with different amino acid substitutions indicated it resides in a unique region important for NBCe1-A function. Our findings demonstrate that the pRTA residues in NBCe1-A are buried in the protein complex/lipid bilayer where they perform important structural roles. PMID:20197274

  19. Early onset acute tubular necrosis following single infusion of zoledronate

    PubMed Central

    Yachoui, Ralph

    2016-01-01

    Summary Zoledronate is a highly potent bisphosphonate widely used in the treatment of postmenopausal osteoporosis. We report the first occurrence of toxic acute tubular necrosis (ATN) following treatment with zoledronate in a patient with osteoporosis. A 63-year-old Caucasian female with rheumatoid arthritis on anti-immune agents received a single dose of zoledronic acid (reclast) for worsening osteoporosis. Twelve days later, she developed renal failure with a rise in serum creatinine from a baseline level of 1.1 mg/dL to 5.5 mg/dL. Renal biopsy showed toxic ATN. Zoledronate was discontinued and the patient had subsequent gradual improvement in renal function with final serum creatinine of 1.8 mg/dL at 1 month of follow up. Careful monitoring of serum creatinine and awareness of the potential nephrotoxicity may avert the development of acute renal failure in osteoporosis patients treated with this agent. PMID:27920815

  20. Evaluation of composite flattened tubular specimen. [fatigue tests

    NASA Technical Reports Server (NTRS)

    Liber, T.; Daniel, I. M.

    1978-01-01

    Flattened tubular specimens of graphite/epoxy, S-glass/epoxy, Kevlar-49/epoxy, and graphite/S-glass/epoxy hybrid materials were evaluated under static and cyclic uniaxial tensile loading and compared directly with flat coupon data of the same materials generated under corresponding loading conditions. Additional development for the refinement of the flattened specimen configuration and fabrication was required. Statically tested graphite/epoxy, S-glass/epoxy, and Kevlar 49/epoxy flattened tube specimens exhibit somewhat higher average strengths than their corresponding flat coupons. Flattened tube specimens of the graphite/S-glass/epoxy hybrid and the graphite/epoxy flattened tube specimens failed in parasitic modes with consequential lower strength than the corresponding flat coupons. Fatigue tested flattened tube specimens failed in parasitic modes resulting in lower fatigue strengths than the corresponding flat coupons.

  1. Clinical approach to renal tubular acidosis in adult patients.

    PubMed

    Reddy, P

    2011-03-01

    Renal tubular acidosis (RTA) is a group of disorders observed in patients with normal anion gap metabolic acidosis. There are three major forms of RTA: A proximal (type II) RTA and two types of distal RTAs (type I and type IV). Proximal (type II) RTA originates from the inability to reabsorb bicarbonate normally in the proximal tubule. Type I RTA is associated with inability to excrete the daily acid load and may present with hyperkalaemia or hypokalaemia. The most prominent abnormality in type IV RTA is hyperkalaemia caused by hypoaldosteronism. This article extensively reviews the mechanism of hydrogen ion generation from metabolism of normal diet and various forms of RTA leading to disruptions of normal acid-base handling by the kidneys.

  2. An experimental investigation of fatigue crack growth in drillstring tubulars

    SciTech Connect

    Dale, B.A.

    1986-01-01

    Drill-string failures continue to plague the oil industry, often costing millions of dollars each year. This problem is frequently intensified with the drilling of deep deviated wellbores or ''hard rock'' drilling conditions. The drilling industry attempts to guard against these costly failures by performing periodic nondestructive inspections to remove damaged tubulars from service. This paper describes the results of full-scale fatigue crack growth tests of drill collars under rotating and bending loads. In addition, corrosion fatigue crack growth data are also presented for API drill-pipe steels in air and in three representative water-base drilling fluid environments. Based on this experimental investigation, the test data support the practical application of fatigue crack growth mechanics principles for the development of nondestructive inspection intervals to reduce drill-string failures.

  3. Mass and heat transfer model of Tubular Solar Still

    SciTech Connect

    Ahsan, Amimul; Fukuhara, Teruyuki

    2010-07-15

    In this paper, a new mass and heat transfer model of a Tubular Solar Still (TSS) was proposed incorporating various mass and heat transfer coefficients taking account of the humid air properties inside the still. The heat balance of the humid air and the mass balance of the water vapor in the humid air were formulized for the first time. As a result, the proposed model enabled to calculate the diurnal variations of the temperature, water vapor density and relative humidity of the humid air, and to predict the hourly condensation flux besides the temperatures of the water, cover and trough, and the hourly evaporation flux. The validity of the proposed model was verified using the field experimental results carried out in Fukui, Japan and Muscat, Oman in 2008. The diurnal variations of the calculated temperatures and water vapor densities had a good agreement with the observed ones. Furthermore, the proposed model can predict the daily and hourly production flux precisely. (author)

  4. Scavenging energy from human motion with tubular dielectric polymer

    NASA Astrophysics Data System (ADS)

    Jean-Mistral, Claire; Basrour, Skandar

    2010-04-01

    Scavenging energy from human motion is a challenge to supply low consumption systems for sport or medical applications. A promising solution is to use electroactive polymers and especially dielectric polymers to scavenge mechanical energy during walk. In this paper, we present a tubular dielectric generator which is the first step toward an integration of these structures into textiles. For a 10cm length and under a strain of 100%, the structure is able to scavenge 1.5μJ for a poling voltage of 200V and up to 40μJ for a poling voltage of 1000V. A 30cm length structure is finally compared to our previous planar structure, and the power management module for those structures is discussed.

  5. Guided growth by a stainless-steel tubular plate.

    PubMed

    Lin, Tung-Yi; Kao, Hsuan-Kai; Li, Wei-Chun; Yang, Wen-E; Chang, Chia-Hsieh

    2013-07-01

    Guided growth using titanium tension band plates is an advancement in the correction of angular deformity. We applied two-hole stainless-steel one-third tubular plates for the same purpose. There were 14 deformities around the knees in eight children, mean age 10.8 years at operation. The success rate was 92.9% (13/14). The average correction rate per month was 0.59° in the femur and 0.65° in the tibia. No premature physeal arrest, overcorrection, or rebound phenomenon was observed. A stainless-steel plate is a safe and effective option for guided growth surgery in countries where only stainless-steel plates are available.

  6. Transient response of a concentric evacuated tubular solar collector

    NASA Astrophysics Data System (ADS)

    Al-Khalil, Kamel M.; Jakubowski, Gerald S.; Springman, Richard A.

    The transient and the steady state performances of an evacuated coaxial tubular solar collector were investigated. A purely implicit central finite differencing numerical technique was used to determine the time-varying temperature distributions in the collector components as well as the fluid exit temperature. Experimental indoor transient tests were conducted in which step inputs of insolation were used. Close agreeement between the experimental and the theoretical results was obtained. The computer model was found to be useful to carry out a complete parametric study. The latter showed that the fluid flow rate had the largest effect on the performance of the collector tube. Lower flow rates resulted in lower efficiencies and longer response times.

  7. Scalable Approach for Extrusion and Perfusion of Tubular, Heterotypic Biomaterials

    NASA Astrophysics Data System (ADS)

    Jeronimo, Mark David

    Soft material tubes are critical in the vasculature of mammalian tissues, forming networks of blood vessels and airways. Homogeneous and heterogeneous hydrogel tubes were extruded in a one-step process using a three layer microfluidic device. Co-axial cylindrical flow of crosslinking solutions and an alginate matrix is generated by a radial arrangement of microfluidic channels at the device's vertical extrusion outlet. The flow is confined and begins a sol-gel transition immediately as it extrudes at velocities upwards of 4 mm/s. This approach allows for predictive control over the dimensions of the rapidly formed tubular structures for outer diameters from 600 microm to 3 mm. A second microfluidic device hosts tube segments for controlled perfusion and pressurization using a reversible vacuum seal. On-chip tube deflection is observed and modeled as a measure of material compliance and circumferential elasticity. I anticipate applications of these devices for perfusion cell culture of cell-laden hydrogel tubes.

  8. [Diagnostic difficulties in a case of constricted tubular visual field].

    PubMed

    Dogaru, Oana-Mihaela; Rusu, Monica; Hâncu, Dacia; Horvath, Kárin

    2013-01-01

    In the paper below we present the clinical case of a 48 year old female with various symptoms associated with functional visual disturbance -constricted tubular visual fields, wich lasts from 6 years; the extensive clinical and paraclinical ophthalmological investigations ruled out the presence of an organic disorder. In the present, we suspect a diagnosis of hysteria, still uncertain, wich represented over time a big challenge in psychology and ophthalmology. The mechanisms and reasons for hysteria are still not clear and it could represent a fascinating research theme. The tunnel, spiral or star-shaped visual fields are specific findings in hysteria for patients who present visual disturbance. The question of whether or not a patient with hysterical visual impairment can or cannot "see" is still unresolved.

  9. Numerical Simulation of Tubular Pumping Systems with Different Regulation Methods

    NASA Astrophysics Data System (ADS)

    Zhu, Honggeng; Zhang, Rentian; Deng, Dongsheng; Feng, Xusong; Yao, Linbi

    2010-06-01

    Since the flow in tubular pumping systems is basically along axial direction and passes symmetrically through the impeller, most satisfying the basic hypotheses in the design of impeller and having higher pumping system efficiency in comparison with vertical pumping system, they are being widely applied to low-head pumping engineering. In a pumping station, the fluctuation of water levels in the sump and discharge pool is most common and at most time the pumping system runs under off-design conditions. Hence, the operation of pump has to be flexibly regulated to meet the needs of flow rates, and the selection of regulation method is as important as that of pump to reduce operation cost and achieve economic operation. In this paper, the three dimensional time-averaged Navier-Stokes equations are closed by RNG κ-ɛ turbulent model, and two tubular pumping systems with different regulation methods, equipped with the same pump model but with different designed system structures, are numerically simulated respectively to predict the pumping system performances and analyze the influence of regulation device and help designers make final decision in the selection of design schemes. The computed results indicate that the pumping system with blade-adjusting device needs longer suction box, and the increased hydraulic loss will lower the pumping system efficiency in the order of 1.5%. The pumping system with permanent magnet motor, by means of variable speed regulation, obtains higher system efficiency partly for shorter suction box and partly for different structure design. Nowadays, the varied speed regulation is realized by varied frequency device, the energy consumption of which is about 3˜4% of output power of the motor. Hence, when the efficiency of variable frequency device is considered, the total pumping system efficiency will probably be lower.

  10. Tubular Scaffold with Shape Recovery Effect for Cell Guide Applications

    PubMed Central

    Hossain, Kazi M. Zakir; Zhu, Chenkai; Felfel, Reda M.; Sharmin, Nusrat; Ahmed, Ifty

    2015-01-01

    Tubular scaffolds with aligned polylactic acid (PLA) fibres were fabricated for cell guide applications by immersing rolled PLA fibre mats into a polyvinyl acetate (PVAc) solution to bind the mats. The PVAc solution was also mixed with up to 30 wt % β-tricalcium phosphate (β-TCP) content. Cross-sectional images of the scaffold materials obtained via scanning electron microscopy (SEM) revealed the aligned fibre morphology along with a significant number of voids in between the bundles of fibres. The addition of β-TCP into the scaffolds played an important role in increasing the void content from 17.1% to 25.3% for the 30 wt % β-TCP loading, which was measured via micro-CT (µCT) analysis. Furthermore, µCT analyses revealed the distribution of aggregated β-TCP particles in between the various PLA fibre layers of the scaffold. The compressive modulus properties of the scaffolds increased from 66 MPa to 83 MPa and the compressive strength properties decreased from 67 MPa to 41 MPa for the 30 wt % β-TCP content scaffold. The scaffolds produced were observed to change into a soft and flexible form which demonstrated shape recovery properties after immersion in phosphate buffered saline (PBS) media at 37 °C for 24 h. The cytocompatibility studies (using MG-63 human osteosarcoma cell line) revealed preferential cell proliferation along the longitudinal direction of the fibres as compared to the control tissue culture plastic. The manufacturing process highlighted above reveals a simple process for inducing controlled cell alignment and varying porosity features within tubular scaffolds for potential tissue engineering applications. PMID:26184328

  11. Tubular Scaffold with Shape Recovery Effect for Cell Guide Applications.

    PubMed

    Hossain, Kazi M Zakir; Zhu, Chenkai; Felfel, Reda M; Sharmin, Nusrat; Ahmed, Ifty

    2015-07-10

    Tubular scaffolds with aligned polylactic acid (PLA) fibres were fabricated for cell guide applications by immersing rolled PLA fibre mats into a polyvinyl acetate (PVAc) solution to bind the mats. The PVAc solution was also mixed with up to 30 wt % β-tricalcium phosphate (β-TCP) content. Cross-sectional images of the scaffold materials obtained via scanning electron microscopy (SEM) revealed the aligned fibre morphology along with a significant number of voids in between the bundles of fibres. The addition of β-TCP into the scaffolds played an important role in increasing the void content from 17.1% to 25.3% for the 30 wt % β-TCP loading, which was measured via micro-CT (µCT) analysis. Furthermore, µCT analyses revealed the distribution of aggregated β-TCP particles in between the various PLA fibre layers of the scaffold. The compressive modulus properties of the scaffolds increased from 66 MPa to 83 MPa and the compressive strength properties decreased from 67 MPa to 41 MPa for the 30 wt % β-TCP content scaffold. The scaffolds produced were observed to change into a soft and flexible form which demonstrated shape recovery properties after immersion in phosphate buffered saline (PBS) media at 37 °C for 24 h. The cytocompatibility studies (using MG-63 human osteosarcoma cell line) revealed preferential cell proliferation along the longitudinal direction of the fibres as compared to the control tissue culture plastic. The manufacturing process highlighted above reveals a simple process for inducing controlled cell alignment and varying porosity features within tubular scaffolds for potential tissue engineering applications.

  12. On milling of thin-wall conical and tubular workpieces

    NASA Astrophysics Data System (ADS)

    Tsai, Mu-Ping; Tsai, Nan-Chyuan; Yeh, Cheng-Wei

    2016-05-01

    Thin-wall tubular-geometry workpieces have been widely applied in aircraft and medical industries. However, due to the special geometry of this kind of workpieces and induced poor machinability, the desired accuracy of machining tends to be greatly degraded, no matter what type of metal-cutting task such as milling, drilling or turning is undertaken. Though numerous research reports are available that the tool path can be planned on the basis of preset surface profile before actual milling operation is performed, it is still difficult to predict the real-time surface profile errors for peripheral milling of thin-wall tubular workpieces. Instead of relying on tool path planning, this research is focused on how to real-time formulate the appropriate applied cutting torque via feedback of spindle motor current. On the other hand, a few suitable cutting conditions which are able to prevent potential break/crack of thin-wall workpieces and enhance productivity but almost retain the same cutting quality is proposed in this research. To achieve this goal, estimated surface profile error on machined parts due to deflections caused by both tool and workpiece is studied at first. Traditionally, by adjusting cutting parameters such as feed rate or cut depth, the deflection of tool or workpiece can be expected not to exceed the specified limit. Instead, an effective feedback control loop is proposed by this work for applying real-time appropriate applied cutting torque to prevent potential break/crack of the thin-wall conical workpieces. The torque estimation approach by spindle motor current feedback and the corresponding fuzzy logic controller are employed. Compared with constant cutting torque during milling operation in tradition manner, it is observed that the time consumption of milling cycle by aid of the aforesaid fuzzy logic controller is greatly shortened while the resulted cutting accuracy upon finish of workpiece can be almost retained.

  13. Facile fabrication of Ag dendrite-integrated anodic aluminum oxide membrane as effective three-dimensional SERS substrate

    NASA Astrophysics Data System (ADS)

    Zhang, Cong-yun; Lu, Ya; Zhao, Bin; Hao, Yao-wu; Liu, Ya-qing

    2016-07-01

    A novel surface enhanced Raman scattering (SERS)-active substrate has been successfully developed, where Ag-dendrites are assembled on the surface and embedded in the channels of anodic aluminum oxide (AAO) membrane, via electrodeposition in AgNO3/PVP aqueous system. Reaction conditions were systematically investigated to attain the best Raman enhancement. The growth mechanism of Ag dendritic nanostructures has been proposed. The Ag dendrite-integrated AAO membrane with unique hierarchical structures exhibits high SERS activity for detecting rhodamine 6G with a detection limit as low as 1 × 10-11 M. Furthermore, the three-dimensional (3D) substrates display a good reproducibility with the average intensity variations at the major Raman peak less than 12%. Most importantly, the 3D SERS substrates without any surface modification show an outstanding SERS response for the molecules with weak affinity for noble metal surfaces. The potential application for the detection of polycyclic aromatic hydrocarbons (PAHs) was evaluated with fluoranthene as Raman target molecule and a sensitive SERS detection with a limit down to 10-8 M was reached. The 3D SERS-active substrate shows promising potential for rapid detection of trace organic pollutants even weak affinity molecules in the environment.

  14. Multicomponent membranes

    DOEpatents

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

    1988-01-01

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

  15. Preparations of an inorganic-framework proton exchange nanochannel membrane

    NASA Astrophysics Data System (ADS)

    Yan, X. H.; Jiang, H. R.; Zhao, G.; Zeng, L.; Zhao, T. S.

    2016-09-01

    In this work, a proton exchange membrane composed of straight and aligned proton conducting nanochannels is developed. Preparation of the membrane involves the surface sol-gel method assisted with a through-hole anodic aluminum oxide (AAO) template to form the framework of the PEM nanochannels. A monomolecular layer (SO3Hsbnd (CH2)3sbnd Sisbnd (OCH3)3) is subsequently added onto the inner surfaces of the nanochannels to shape a proton-conducting pathway. Straight nanochannels exhibit long range order morphology, contributing to a substantial improvement in the proton mobility and subsequently proton conductivity. In addition, the nanochannel size can be altered by changing the surface sol-gel condition, allowing control of the active species/charge carrier selectivity via pore size exclusion. The proton conductivity of the nanochannel membrane is reported as high as 11.3 mS cm-1 at 70 °C with a low activation energy of 0.21 eV (20.4 kJ mol-1). First-principle calculations reveal that the activation energy for proton transfer is impressively low (0.06 eV and 0.07 eV) with the assistance of water molecules.

  16. Twist relates to tubular epithelial-mesenchymal transition and interstitial fibrogenesis in the obstructed kidney.

    PubMed

    Kida, Yujiro; Asahina, Kinji; Teraoka, Hirobumi; Gitelman, Inna; Sato, Tetsuji

    2007-07-01

    Epithelial-mesenchymal transition (EMT) is a critical step in renal fibrosis. It has been recently reported that a transcription factor, Twist, plays a pivotal role in metastasis of breast tumors by inducing EMT. In this study, we examined whether Twist relates to renal fibrogenesis including EMT of tubular epithelia, evaluating Twist expression level in the unilateral ureteral obstruction (UUO) model. Kidneys of mice subjected to UUO were harvested 1, 3, 7, and 10 days after obstruction. Compared with control kidneys, Twist mRNA-level significantly increased 3 days after UUO (UUO day 3 kidney) and further augmented until 10 days after UUO. Twist expression increased in tubular epithelia of the dilated tubules and the expanded interstitial areas of UUO kidneys, where cell-proliferating appearances were frequently found in a time-dependent manner. Although a part of tubular cells in whole nephron segment were immunopositive for Twist in UUO day 7 kidneys, tubular epithelia downstream of nephron more frequently expressed Twist than upstream of nephron. In UUO day 7 kidneys, some tubular epithelia were confirmed to coexpress Twist and fibroblast-specific protein-1, a marker for EMT, indicating that Twist is involved in tubular EMT under pathological state. Twist was expressed also in a number of alpha-smooth muscle actin-positive myofibroblasts located in the expanded interstitial area of UUO kidneys. From these findings, the present investigation suggests that Twist is associated with tubular EMT, proliferation of myofibroblasts, and subsequent renal fibrosis in obstructed kidneys.

  17. Ceramic membranes for high temperature hydrogen separation

    SciTech Connect

    Fain, D.E.; Roettger, G.E.

    1996-08-01

    Ceramic gas separation membranes can provide very high separation factors if the pore size is sufficiently small to separate gas molecules by molecular sieving and if oversized pores are adequately limited. Ceramic membranes typically have some pores that are substantially larger than the mean pore size and that should be regarded as defects. To assess the effects of such defects on the performance of ceramic membranes, a simple mathematical model has been developed to describe flow through a gas separation membrane that has a primary mode of flow through very small pores but that has a secondary mode of flow through undesirably large pores. This model permits separation factors to be calculated for a specified gas pair as a function of the molecular weights and molecular diameters of the gases, the membrane pore diameter, and the diameter and number of defects. This model will be described, and key results from the model will be presented. The separation factors of the authors membranes continue to be determined using a permeance test system that measures flows of pure gases through a membrane at temperatures up to 275{degrees}C. A primary goal of this project for FY 1996 is to develop a mixed gas separation system for measuring the separation efficiency of membranes at higher temperatures. Performance criteria have been established for the planned mixed gas separation system and design of the system has been completed. The test system is designed to measure the separation efficiency of membranes at temperatures up to 600{degrees}C and pressures up to 100 psi by separating the constituents of a gas mixture containing hydrogen. The system will accommodate the authors typical experimental membrane that is tubular and has a diameter of about 9 mm and a length of about 23 cm. The design of the new test system and its expected performance will be discussed.

  18. Tweak induces proliferation in renal tubular epithelium: a role in uninephrectomy induced renal hyperplasia

    PubMed Central

    Sanz, Ana B; Sanchez-Niño, Maria Dolores; Izquierdo, Maria Concepcion; Jakubowski, Aniela; Justo, Pilar; Blanco-Colio, Luis M; Ruiz-Ortega, Marta; Egido, Jesús; Ortiz, Alberto

    2009-01-01

    The tumour necrosis factor (TNF) family member TWEAK activates the Fn14 receptor and has pro-apoptotic, proliferative and pro-inflammatory actions that depend on the cell type and the microenvironment. We explored the proliferative actions of TWEAK on cultured tubular cells and in vivo on renal tubules. Additionally, we studied the role of TWEAK in compensatory proliferation following unilateral nephrectomy and in an inflammatory model of acute kidney injury (AKI) induced by a folic acid overdose. TWEAK increased the proliferation, cell number and cyclin D1 expression of cultured tubular cells, in vitro. Exposure to serum increased TWEAK and Fn14 expression and the proliferative response to TWEAK. TWEAK activated the mitogen-activated protein kinases ERK and p38, the phosphatidyl-inositol 3-kinase (PI3K)/Akt pathway and NF-κB. TWEAK-induced proliferation was prevented by inhibitors of these protein kinases and by the NF-κB inhibitor parthenolide. TWEAK-induced tubular cell proliferation as assessed by PCNA and cyclin D1 expression in the kidneys of adult healthy mice in vivo. By contrast, TWEAK knock-out mice displayed lower tubular cell proliferation in the remnant kidney following unilateral nephrectomy, a non-inflammatory model. This is consistent with TWEAK-induced proliferation on cultured tubular cells in the absence of inflammatory cytokines. Consistent with our previously published data, in the presence of inflammatory cytokines TWEAK promoted apoptosis, not proliferation, of cultured tubular cells. In this regard, TWEAK knock-out mice with AKI displayed less tubular apoptosis and proliferation, as well as improved renal function. In conclusion, TWEAK actions in tubular cells are context dependent. In a non-inflammatory milieu TWEAK induces proliferation of tubular epithelium. This may be relevant for compensatory renal hyperplasia following nephrectomy. PMID:19426154

  19. Industrial membrane processes in the treatment of process waters and liquors.

    PubMed

    Mänttäri, M; Kallioinen, M; Pihlajamäki, A; Nyström, M

    2010-01-01

    A review on pulp and paper industrial membrane processes using a variety of modules and processes is presented. Membranes are mostly used today to purify process waters and to recover coating colours. Ultrafiltration using tubular membrane modules or cross-rotational (CR) filtration has been widely applied for the purification of process waters. The reuse of UF membrane permeate has decreased the fresh water consumption to lower than 6 m³/t of paper in some paper machines. Some industrial membrane processes also recover valuable products from different streams (e.g lignosulphonates). Membranes are also combined with biological degradation processes in some paper mills. Nanofiltration has been used to purify the effluents discharged from the activated sludge process. At least two reverse osmosis plants purify river water to be used as raw water in the mill. Furthermore, advantages of different membrane modules and the current ways to treat membrane concentrate are discussed.

  20. Kidney specific protein-positive cells derived from embryonic stem cells reproduce tubular structures in vitro and differentiate into renal tubular cells.

    PubMed

    Morizane, Ryuji; Monkawa, Toshiaki; Fujii, Shizuka; Yamaguchi, Shintaro; Homma, Koichiro; Matsuzaki, Yumi; Okano, Hideyuki; Itoh, Hiroshi

    2014-01-01

    Embryonic stem cells and induced pluripotent stem cells have the ability to differentiate into various organs and tissues, and are regarded as new tools for the elucidation of disease mechanisms as well as sources for regenerative therapies. However, a method of inducing organ-specific cells from pluripotent stem cells is urgently needed. Although many scientists have been developing methods to induce various organ-specific cells from pluripotent stem cells, renal lineage cells have yet to be induced in vitro because of the complexity of kidney structures and the diversity of kidney-component cells. Here, we describe a method of inducing renal tubular cells from mouse embryonic stem cells via the cell purification of kidney specific protein (KSP)-positive cells using an anti-KSP antibody. The global gene expression profiles of KSP-positive cells derived from ES cells exhibited characteristics similar to those of cells in the developing kidney, and KSP-positive cells had the capacity to form tubular structures resembling renal tubular cells when grown in a 3D culture in Matrigel. Moreover, our results indicated that KSP-positive cells acquired the characteristics of each segment of renal tubular cells through tubular formation when stimulated with Wnt4. This method is an important step toward kidney disease research using pluripotent stem cells, and the development of kidney regeneration therapies.

  1. Chronicity following ischaemia-reperfusion injury depends on tubular-macrophage crosstalk involving two tubular cell-derived CSF-1R activators: CSF-1 and IL-34.

    PubMed

    Sanchez-Niño, Maria Dolores; Sanz, Ana Belen; Ortiz, Alberto

    2016-09-01

    Two structurally unrelated ligands activate the macrophage colony stimulating factor receptor (CSF-1R, c-fms, CD115): M-CSF/CSF-1 and interleukin-34 (IL-34). Both ligands promote macrophage proliferation, survival and differentiation. IL-34 also activates the protein-tyrosine phosphatase ζ receptor (PTP-ζ, PTPRZ1). Both receptors and cytokines are increased during acute kidney injury. While tubular cell-derived CSF-1 is required for kidney repair, Baek et al (J Clin Invest 2015; 125: 3198-3214) have now identified tubular epithelial cell-derived IL-34 as a promoter of kidney neutrophil and macrophage infiltration and tubular cell destruction during experimental kidney ischaemia-reperfusion, leading to chronic injury. IL-34 promoted proliferation of both intrarenal macrophages and bone marrow cells, increasing circulating neutrophils and monocytes and their kidney recruitment. Thus, injured tubular cells release two CSF-1R activators, one (CSF-1) that promotes tubular cell survival and kidney repair and another (IL-34) that promotes chronic kidney damage. These results hold promise for the development of IL-34-targeting strategies to prevent ischaemia-reperfusion kidney injury in contexts such as kidney transplantation. However, careful consideration should be given to the recent characterization by Bezie et al. (J Clin Invest 2015; 125: 3952-3964) of IL-34 as a T regulatory cell (Treg) cytokine that modulates macrophage responses so that IL-34-primed macrophages potentiate the immune suppressive capacity of Tregs and promote graft tolerance.

  2. Undulating tubular liposomes through incorporation of a synthetic skin ceramide into phospholipid bilayers.

    PubMed

    Xu, Peng; Tan, Grace; Zhou, Jia; He, Jibao; Lawson, Louise B; McPherson, Gary L; John, Vijay T

    2009-09-15

    Nonspherical liposomes were prepared by doping L-alpha-phosphatidylcholine (PC) with ceramide VI (a skin lipid). Cryo-transmission electron microscopy shows the liposome shape changing from spherical to an undulating tubular morphology, when the amount of ceramide VI is increased. The formation of tubular liposomes is energetically favorable and is attributed to the association of ceramide VI with PC creating regions of lower curvature. Since ceramides are the major component of skin lipids in the stratum corneum, tubular liposomes containing ceramide may potentially serve as self-enhanced nanocarriers for transdermal delivery.

  3. Undulating tubular liposomes through incorporation of a synthetic skin ceramide into phospholipid bilayers

    PubMed Central

    Xu, Peng; Tan, Grace; Zhou, Jia; He, Jibao; Lawson, Louise B.; McPherson, Gary L.; John, Vijay T.

    2009-01-01

    Non-spherical liposomes were prepared by doping L-α-phosphatidylcholine (PC) with ceramide VI (a skin lipid). Cryo-transmission electron microscopy shows the liposome shape changing from spherical to an undulating tubular morphology, when the amount ofceramide VI is increased. The formation of tubular liposomes is energetically favorableand is attributed to the association of ceramide VI with PC creating regions of lower curvature. Since ceramides are the major component of skin lipids inthe stratum corneum, tubular liposomes containing ceramide may potentially serve as self-enhanced nanocarriers for transdermal delivery. PMID:19694462

  4. Factors affecting plant growth in membrane nutrient delivery

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  5. Membrane-free microfiltration by asymmetric inertial migration

    NASA Astrophysics Data System (ADS)

    Seo, Jeonggi; Lean, Meng H.; Kole, Ashutosh

    2007-07-01

    Membrane-free microfiltration by asymmetric inertial migration is studied and evidence of the filtration capability is presented. Centrifugal force induced by flow in spiral channel geometry modifies the lateral symmetry of straight-channel tubular pinch equilibrium resulting in a focused particle band nearer to the inner sidewall. Bifurcated outlets separately collect the concentrated particle band and remaining effluent. The spiral continuous flow filtration relies solely on internal fluidic shear characteristics, eliminating the need for membrane filters or external force fields. This device has the desirable combinations of high throughput and low cost, making it inherently suited for preparative filtration in the range of micro- to macroscale applications.

  6. Tubular overexpression of Gremlin in transgenic mice aggravates renal damage in diabetic nephropathy.

    PubMed

    Marchant, Vanessa; Droguett, Alejandra; Valderrama, Graciela; Burgos, M Eugenia; Carpio, Daniel; Kerr, Bredford; Ruiz-Ortega, Marta; Egido, Jesús; Mezzano, Sergio

    2015-09-15

    Diabetic nephropathy (DN) is currently a leading cause of end-stage renal failure worldwide. Gremlin was identified as a gene differentially expressed in mesangial cells exposed to high glucose and in experimental diabetic kidneys. We have described that Gremlin is highly expressed in biopsies from patients with diabetic nephropathy, predominantly in areas of tubulointerstitial fibrosis. In streptozotocin (STZ)-induced experimental diabetes, Gremlin deletion using Grem1 heterozygous knockout mice or by gene silencing, ameliorates renal damage. To study the in vivo role of Gremlin in renal damage, we developed a diabetic model induced by STZ in transgenic (TG) mice expressing human Gremlin in proximal tubular epithelial cells. The albuminuria/creatinuria ratio, determined at week 20 after treatment, was significantly increased in diabetic mice but with no significant differences between transgenic (TG/STZ) and wild-type mice (WT/STZ). To assess the level of renal damage, kidney tissue was analyzed by light microscopy (periodic acid-Schiff and Masson staining), electron microscopy, and quantitative PCR. TG/STZ mice had significantly greater thickening of the glomerular basement membrane, increased mesangial matrix, and podocytopenia vs. WT/STZ. At the tubulointerstitial level, TG/STZ showed increased cell infiltration and mild interstitial fibrosis. In addition, we observed a decreased expression of podocin and overexpression of monocyte chemoattractant protein-1 and fibrotic-related markers, including transforming growth factor-β1, Col1a1, and α-smooth muscle actin. Together, these results show that TG mice overexpressing Gremlin in renal tubules develop greater glomerular and tubulointerstitial injury in response to diabetic-mediated damage and support the involvement of Gremlin in diabetic nephropathy.

  7. Strap grid tubular plate—a new positive plate for lead-acid batteries. Processes of residual sulphation of the positive plate

    NASA Astrophysics Data System (ADS)

    Pavlov, D.; Papazov, G.; Monahov, B.

    For almost a century now the tubular plate design has been based on cylindrical tubes and spines. The contact surface between the positive active mass (PAM) and the spine is small, which results in high polarisation of the plate at high discharge currents and low power output of the cell. In an attempt to eliminate these disadvantages, the shape of the tubes has been changed to flattened elliptic and the spines have been replaced by strap grids. The thickness of this new type of tubular plate, strap grid tubular plate (SGTP), is between 3 and 5 mm. Batteries with tubular plates of the new design (SGTP batteries) can be used in electric vehicle (EV) and photovoltaic (PV) system applications. This paper presents results of SGTP battery tests according to the European standards for EV, hybrid electric vehicle (HEV) and photovoltaic (PV) system batteries. SGTP batteries have a cycle life of 1000 ECE-15-EV cycles, 6000 ECE-HEV cycles and more than eight gross PV cycles. The optimum battery charge algorithm for VRLA batteries with strap grid tubular plates has been established and the mechanism of disintegration of the positive active mass has been disclosed. The following phenomena are responsible for the decline in capacity of the positive plates. First, when the PAM is built up of globules adhering closely to each other, a strong skeleton with thick aggregates (branches) with a membrane surface is formed. The surface layer of the branches impedes the access of H 2O and H 2SO 4 to their interior thus reducing the utilisation of the PAM. Besides, internal stresses are created in the aggregates, which cause them to crack. Secondly, when the PAM is built up of individual agglomerates with micropores in between, a porous mass with large surface is formed. The tubes keep the aggregates together and prolong the cycle life of the battery. During discharge, the contacts between the aggregates weaken and the capacity declines. Third, during discharge, the H 2SO 4 concentration

  8. Deafness and renal tubular acidosis in mice lacking the K-Cl co-transporter Kcc4.

    PubMed

    Boettger, Thomas; Hübner, Christian A; Maier, Hannes; Rust, Marco B; Beck, Franz X; Jentsch, Thomas J

    2002-04-25

    Hearing depends on a high K(+) concentration bathing the apical membranes of sensory hair cells. K(+) that has entered hair cells through apical mechanosensitive channels is transported to the stria vascularis for re-secretion into the scala media(). K(+) probably exits outer hair cells by KCNQ4 K(+) channels(), and is then transported by means of a gap junction system connecting supporting Deiters' cells and fibrocytes() back to the stria vascularis. We show here that mice lacking the K(+)/Cl(-) (K-Cl) co-transporter Kcc4 (coded for by Slc12a7) are deaf because their hair cells degenerate rapidly after the beginning of hearing. In the mature organ of Corti, Kcc4 is restricted to supporting cells of outer and inner hair cells. Our data suggest that Kcc4 is important for K(+) recycling() by siphoning K(+) ions after their exit from outer hair cells into supporting Deiters' cells, where K(+) enters the gap junction pathway. Similar to some human genetic syndromes(), deafness in Kcc4-deficient mice is associated with renal tubular acidosis. It probably results from an impairment of Cl(-) recycling across the basolateral membrane of acid-secreting alpha-intercalated cells of the distal nephron.

  9. Ceramic membranes for high temperature hydrogen separation

    SciTech Connect

    Adcock, K.D.; Fain, D.E.; James, D.L.; Powell, L.E.; Raj, T.; Roettger, G.E.; Sutton, T.G.

    1997-12-01

    The separative performance of the authors` ceramic membranes has been determined in the past using a permeance test system that measured flows of pure gases through a membrane at temperatures up to 275 C. From these data, the separation factor was determined for a particular gas pair from the ratio of the pure gas specific flows. An important project goal this year has been to build a Mixed Gas Separation System (MGSS) for measuring the separation efficiencies of membranes at higher temperatures and using mixed gases. The MGSS test system has been built, and initial operation has been achieved. The MGSS is capable of measuring the separation efficiency of membranes at temperatures up to 600 C and pressures up to 100 psi using a binary gas mixture such as hydrogen/methane. The mixed gas is fed into a tubular membrane at pressures up to 100 psi, and the membrane separates the feed gas mixture into a permeate stream and a raffinate stream. The test membrane is sealed in a stainless steel holder that is mounted in a split tube furnace to permit membrane separations to be evaluated at temperatures up to 600 C. The compositions of the three gas streams are measured by a gas chromatograph equipped with thermal conductivity detectors. The test system also measures the temperatures and pressures of all three gas streams as well as the flow rate of the feed stream. These data taken over a range of flows and pressures permit the separation efficiency to be determined as a function of the operating conditions. A mathematical model of the separation has been developed that permits the data to be reduced and the separation factor for the membrane to be determined.

  10. Novel tubular and crystalline structures in purified preparations of Newcastle disease virus. Brief report.

    PubMed

    Gowans, E J; McNulty, M S

    1979-01-01

    Hitherto undescribed tubular and crystalline structures were detected by negative contrast electron microscopy in purified preparations of Newcastle disease virus. It is suggested that these are viral in origin and are composed of aggregates of viral glycoprotein.

  11. Bubble-Free Propulsion of Ultrasmall Tubular Nanojets Powered by Biocatalytic Reactions

    PubMed Central

    2016-01-01

    The motion of self-propelled tubular micro- and nanojets has so far been achieved by bubble propulsion, e.g., O2 bubbles formed by catalytic decomposition of H2O2, which renders future biomedical applications inviable. An alternative self-propulsion mechanism for tubular engines on the nanometer scale is still missing. Here, we report the fabrication and characterization of bubble-free propelled tubular nanojets (as small as 220 nm diameter), powered by an enzyme-triggered biocatalytic reaction using urea as fuel. We studied the translational and rotational dynamics of the nanojets as functions of the length and location of the enzymes. Introducing tracer nanoparticles into the system, we demonstrated the presence of an internal flow that extends into the external fluid via the cavity opening, leading to the self-propulsion. One-dimensional nanosize, longitudinal self-propulsion, and biocompatibility make the tubular nanojets promising for future biomedical applications. PMID:27718566

  12. Bubble-Free Propulsion of Ultrasmall Tubular Nanojets Powered by Biocatalytic Reactions.

    PubMed

    Ma, Xing; Hortelao, Ana C; Miguel-López, Albert; Sánchez, Samuel

    2016-10-26

    The motion of self-propelled tubular micro- and nanojets has so far been achieved by bubble propulsion, e.g., O2 bubbles formed by catalytic decomposition of H2O2, which renders future biomedical applications inviable. An alternative self-propulsion mechanism for tubular engines on the nanometer scale is still missing. Here, we report the fabrication and characterization of bubble-free propelled tubular nanojets (as small as 220 nm diameter), powered by an enzyme-triggered biocatalytic reaction using urea as fuel. We studied the translational and rotational dynamics of the nanojets as functions of the length and location of the enzymes. Introducing tracer nanoparticles into the system, we demonstrated the presence of an internal flow that extends into the external fluid via the cavity opening, leading to the self-propulsion. One-dimensional nanosize, longitudinal self-propulsion, and biocompatibility make the tubular nanojets promising for future biomedical applications.

  13. The fouling in the tubular heat exchanger of Algiers refinery

    NASA Astrophysics Data System (ADS)

    Harche, Rima; Mouheb, Abdelkader; Absi, Rafik

    2016-05-01

    Crude oil fouling in refinery preheat exchangers is a chronic operational problem that compromises energy recovery in these systems. Progress is hindered by the lack of quantitative knowledge of the dynamic effects of fouling on heat exchanger transfer and pressure drops. In subject of this work is an experimental determination of the thermal fouling resistance in the tubular heat exchanger of the crude oil preheats trains installed in an Algiers refinery. By measuring the inlet and outlet temperatures and mass flows of the two fluids, the overall heat transfer coefficient has been determined. Determining the overall heat transfer coefficient for the heat exchanger with clean and fouled surfaces, the fouling resistance was calculated. The results obtained from the two cells of exchangers studies, showed that the fouling resistance increased with time presented an exponential evolution in agreement with the model suggested by Kern and Seaton, with the existence of fluctuation caused by the instability of the flow rate and the impact between the particles. The bad cleaning of the heat exchangers involved the absence of the induction period and caused consequently, high values of the fouling resistance in a relatively short period of time.

  14. HIGH-TEMPERATURE TUBULAR SOLID OXIDE FUEL CELL GENERATOR DEVELOPMENT

    SciTech Connect

    S.E. Veyo

    1998-09-01

    During the Westinghouse/USDOE Cooperative Agreement period of November 1, 1990 through November 30, 1997, the Westinghouse solid oxide fuel cell has evolved from a 16 mm diameter, 50 cm length cell with a peak power of 1.27 watts/cm to the 22 mm diameter, 150 cm length dimensions of today's commercial prototype cell with a peak power of 1.40 watts/cm. Accompanying the increase in size and power density was the elimination of an expensive EVD step in the manufacturing process. Demonstrated performance of Westinghouse's tubular SOFC includes a lifetime cell test which ran for a period in excess of 69,000 hours, and a fully integrated 25 kWe-class system field test which operated for over 13,000 hours at 90% availability with less than 2% performance degradation over the entire period. Concluding the agreement period, a 100 kW SOFC system successfully passed its factory acceptance test in October 1997 and was delivered in November to its demonstration site in Westervoort, The Netherlands.

  15. Standing wave brass-PZT square tubular ultrasonic motor.

    PubMed

    Park, Soonho; He, Siyuan

    2012-09-01

    This paper reports a standing wave brass-PZT tubular ultrasonic motor. The motor is composed of a brass square tube with two teeth on each tube end. Four PZT plates are attached to the outside walls of the brass tube. The motor requires only one driving signal to excite vibration in a single bending mode to generate reciprocating diagonal trajectories of teeth on the brass tube ends, which drive the motor to rotate. Bi-directional rotation is achieved by exciting different pairs of PZT plates to switch the bending vibration direction. Through using the brass-PZT tube structure, the motor can take high magnitude vibration to achieve a high output power in comparison to PZT tube based ultrasonic motors. Prototypes are fabricated and tested. The dimension of the brass-PZT tube is 3.975mm×3.975mm×16mm. Measured performance is a no-load speed of >1000RPM, a stall torque of 370μNm and a maximum output power of 16 mW when a sinusoidal driving voltage of 50V is applied. The working frequencies of the motor are 46,050Hz (clockwise) and 46,200Hz (counter-clockwise).

  16. A single vibration mode tubular piezoelectric ultrasonic motor.

    PubMed

    He, Siyuan; Chiarot, Paul R; Park, Soonho

    2011-05-01

    A novel tubular ultrasonic motor is presented that uses only a single vibration bending mode of a piezoelectric tube to generate rotation. When the piezoelectric tube bends, the diagonal motion of points on selected areas at the ends of the tube generates forces with tangential components along the same circumferential direction, driving the rotors to rotate. Bi-directional motion is achieved by simply switching the direction of bending. Because only one vibration mode is used, the motor requires only one driving signal and no vibration mode coupling is needed, simplifying the design, fabrication, assembly, and operation of the device. Two prototypes [one with cut-in lead zirconate titanate (PZT) teeth and one with added metal teeth] were built and tested using PZT tubes available to the authors. The tubes have an outside diameter of 6.6 mm, inner diameter of 5.0 mm, and length of 25.4 mm. The working frequencies of the two motors are 27.6 and 23.5 kHz. The motors achieved a maximum no-load speed of 400 rpm and a stall torque of 300 μN·m.

  17. Combined hot-spot stress procedures for tubular joints

    SciTech Connect

    Buitrayo, J.; Kahlich, J.L.; Zettlemoyer, N.

    1984-05-01

    An alternative procedure for predicting the combined hot-spot stress (CHSS) at tubular K and Y joints under combined branch loading is presented. The procedure makes use of influence factor (IF) equations developed, as a function of the joint geometry and branch loading, for various potential hot-spot locations on the branch and chord sides of the weld. The CHSS is obtained by lineraly superimposing, at a point, the effects of the axial force and bending moments acting on each branch. The resulting CHSS, therefore, reflects location, orientation and sign of each branch load contribution. Comparisons of predicted CHSS obtained via the new and other procedures to stresses from finite element analyses were made on a large sample of joints. Result show that (1) the new procedure is substantially more reliable than the other procedures studied, (2) none of the procedures consistently predicts conservative CHSS values, and (3) the overriding factor influencing the accuracy of the CHSS calculations appears to be the accuracy of the parametric equations. Although a better stress predictor can be expected to yield more reliable fatigue damage estimates, damage calculations will exhibit broad scatter due to the power function relating damage to stress. Unfortunately, further improvements in the accuracy of CHSS based on parametric equations are not likely to be easily achieved, given the large number of variables and locations that need to be considered.

  18. Bioprocess kinetics in a horizontal rotating tubular bioreactor.

    PubMed

    Ivancić, M; Santek, B; Novak, S; Horvat, P; Marić, V

    2004-04-01

    A horizontal rotating tubular bioreactor (HRTB) is a plug flow bioreactor whose interior is provided with O-ring-shaped partition walls that serve as carriers for microbial biomass. During this investigation, microbial biomass was grown in suspension and on the bioreactor inner surface as a microbial biofilm with average mass that was considerably higher than suspended biomass. The dynamics of bioprocess in HRTB was studied by different combinations of process parameters (bioreactor rotation speed and mean residence time) and it was monitored by withdrawing the samples from five positions along the bioreactor. During this investigation it was also observed that mean residence time had a more pronounced effect on the bioprocess dynamics than bioreactor rotation speed. For the description of bioprocess kinetics in HRTB an unstructured kinetic model was established that defines biomass growth, product formations and substrate consumption rate by using a modified Monod (Levenspiel) model. This kinetic model defines changes in suspension and in microbial biofilm, and it shows relatively good agreement with experimental data.

  19. Design and Analysis of Tubular Permanent Magnet Linear Wave Generator

    PubMed Central

    Si, Jikai; Feng, Haichao; Su, Peng; Zhang, Lufeng

    2014-01-01

    Due to the lack of mature design program for the tubular permanent magnet linear wave generator (TPMLWG) and poor sinusoidal characteristics of the air gap flux density for the traditional surface-mounted TPMLWG, a design method and a new secondary structure of TPMLWG are proposed. An equivalent mathematical model of TPMLWG is established to adopt the transformation relationship between the linear velocity of permanent magnet rotary generator and the operating speed of TPMLWG, to determine the structure parameters of the TPMLWG. The new secondary structure of the TPMLWG contains surface-mounted permanent magnets and the interior permanent magnets, which form a series-parallel hybrid magnetic circuit, and their reasonable structure parameters are designed to get the optimum pole-arc coefficient. The electromagnetic field and temperature field of TPMLWG are analyzed using finite element method. It can be included that the sinusoidal characteristics of air gap flux density of the new secondary structure TPMLWG are improved, the cogging force as well as mechanical vibration is reduced in the process of operation, and the stable temperature rise of generator meets the design requirements when adopting the new secondary structure of the TPMLWG. PMID:25050388

  20. Probing chirality of a lipid tubular by confocal Raman microscopy.

    PubMed

    Kiang-ia, Jarinee; Hailong, Hu; Bin, Yan; Jantippana, Yuwathida; Pantu, Piboon; Limtrakul, Jumras; Chattham, Nattaporn; Zexiang, Shen; Ting, Yu

    2010-11-01

    The chiral phospholipids 1,2-bis-(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DC8,9 PC) can self assemble into lipid nanotubules. This hollow cylindrical supramolecular structure shows promise in a number of biotechnological applications. The mechanism of lipid tubule formation was initiated by assembling of lipid bilayer sheets from amphiphilic solution. Upon cooling, small ribbons were detached from the sheets and rolled up into helical tubules. The lipid tubules obtained were 0.6-0.8 microm in diameter and approximately 50 microm in length. Raman spectra of individual polymerized lipid tubules were measured by focused laser excitation of 532 nm leading to intense and reproducible Raman spectra. The chirality of lipid tubules was investigated by atomic force microscopy (AFM) and confocal Raman microscopy. We report the Raman mapping images revealing helical tubular profiles of C=C stretching and C[triple bond]C stretching of lipid tubules. Circular dichroism property of lipid tubules has also been probed with a 532 nm laser.

  1. Reducing the Manufacturing Cost of Tubular SOFC Technology

    SciTech Connect

    George, R.A.; Bessette, N.F.

    1997-12-31

    In recent years, Westinghouse Electric Corporation has made great strides in advancing tubular solid oxide fuel cell (SOFC) technology towards commercialization by the year 2001. In 1993, Westinghouse initiated a program to develop a `MWe Class` (1-3 MWe) pressurized SOFC (PSOFC) gas turbine (GT) combined cycle power system for distributed power applications because of its: (1) ultra high efficiency (approx. 63% net AC/LHV CH{sub 4}), (2) its compatibility with a factory packaged, minimum site work philosophy, and (3) its cost effectiveness. Since then two cost studies on this market entry product performed by consultants to the U.S. Department of Energy have confirmed Westinghouse cost studies that fully installed costs of under $1300/kWe can be achieved in the early commercialization years for such small PSOFC/GT power systems. The paper will present the results of these cost studies in the areas of cell manufacturing cost, PSOFC generator manufacturing cost, balance-of-plant (BOP) cost, and system installation cost. In addition, cost of electricity calculations will be presented.

  2. Macroscopic, freestanding, and tubular graphene architectures fabricated via thermal annealing.

    PubMed

    Nguyen, Duc Dung; Suzuki, Seiya; Kato, Shuji; To, Bao Dong; Hsu, Chia Chen; Murata, Hidekazu; Rokuta, Eiji; Tai, Nyan-Hwa; Yoshimura, Masamichi

    2015-03-24

    Manipulation of individual graphene sheets/films into specific architectures at macroscopic scales is crucially important for practical uses of graphene. We present herein a versatile and robust method based on annealing of solid carbon precursors on nickel templates and thermo-assisted removal of poly(methyl methacrylate) under low vacuum of ∼0.6 Pa for fabrication of macroscopic, freestanding, and tubular graphene (TG) architectures. Specifically, the TG architectures can be obtained as individual and woven tubes with a diameter of ∼50 μm, a wall thickness in the range of 2.1-2.9 nm, a density of ∼1.53 mg·cm(-3), a thermal stability up to 600 °C in air, an electrical conductivity of ∼1.48 × 10(6) S·m(-1), and field emission current densities on the order of 10(4) A·cm(-2) at low applied electrical fields of 0.6-0.7 V·μm(-1). These properties show great promise for applications in flexible and lightweight electronics, electron guns, or X-ray tube sources.

  3. Tubular Overexpression of Angiopoietin-1 Attenuates Renal Fibrosis

    PubMed Central

    Lee, Heedoo; Kim, Yeawon; Liu, Tuoen; Guo, Qiusha; Geminiani, Julio J.; Austin, Paul F.; Chen, Ying Maggie

    2016-01-01

    Emerging evidence has highlighted the pivotal role of microvasculature injury in the development and progression of renal fibrosis. Angiopoietin-1 (Ang-1) is a secreted vascular growth factor that binds to the endothelial-specific Tie2 receptor. Ang-1/Tie2 signaling is critical for regulating blood vessel development and modulating vascular response after injury, but is dispensable in mature, quiescent vessels. Although dysregulation of vascular endothelial growth factor (VEGF) signaling has been well studied in renal pathologies, much less is known about the role of the Ang-1/Tie2 pathway in renal interstitial fibrosis. Previous studies have shown contradicting effects of overexpressing Ang-1 systemically on renal tubulointerstitial fibrosis when different engineered forms of Ang-1 are used. Here, we investigated the impact of site-directed expression of native Ang-1 on the renal fibrogenic process and peritubular capillary network by exploiting a conditional transgenic mouse system [Pax8-rtTA/(TetO)7 Ang-1] that allows increased tubular Ang-1 production in adult mice. Using a murine unilateral ureteral obstruction (UUO) fibrosis model, we demonstrate that targeted Ang-1 overexpression attenuates myofibroblast activation and interstitial collagen I accumulation, inhibits the upregulation of transforming growth factor β1 and subsequent phosphorylation of Smad 2/3, dampens renal inflammation, and stimulates the growth of peritubular capillaries in the obstructed kidney. Our results suggest that Ang-1 is a potential therapeutic agent for targeting microvasculature injury in renal fibrosis without compromising the physiologically normal vasculature in humans. PMID:27454431

  4. The thermal decomposition of methane in a tubular reactor

    SciTech Connect

    Kobayashi, Atsushi; Steinberg, M.

    1992-01-01

    The reaction rate of methane decomposition using a tubular reactor having a 1 inch inside diameter with an 8 foot long heated zone was investigated in the temperature range of 700 to 900 C with pressures ranging from 28.2 to 56.1 atm. Representing the rate by a conventional model, {minus}dC{sub CH4}/dt= k1 C{sub CH4} {minus}k2 C{sub H2}{sup 2}, the rate constant k1 for methane decomposition was determined. The activation energy, 31.3 kcal/mol, calculated by an Arrhenius Plot was lower than for previously published results for methane decomposition. This result indicates that submicron particles found in the reactor adhere to the inside of the reactor and these submicron high surface area carbon particles tend to catalyze the methane decomposition. The rate constant has been found to be approximately constant at 900 C with pressure range cited above. The rate of methane decomposition increases with methane partial pressure in first-order. The rate of the methane decomposition is favored by higher temperatures and pressures while the thermochemical equilibrium of methane decomposition is favored by lower pressures. 8 refs., 7 figs., 2 tabs.

  5. Etiopathology of chronic tubular, glomerular and renovascular nephropathies: clinical implications.

    PubMed

    López-Novoa, José M; Rodríguez-Peña, Ana B; Ortiz, Alberto; Martínez-Salgado, Carlos; López Hernández, Francisco J

    2011-01-20

    Chronic kidney disease (CKD) comprises a group of pathologies in which the renal excretory function is chronically compromised. Most, but not all, forms of CKD are progressive and irreversible, pathological syndromes that start silently (i.e. no functional alterations are evident), continue through renal dysfunction and ends up in renal failure. At this point, kidney transplant or dialysis (renal replacement therapy, RRT) becomes necessary to prevent death derived from the inability of the kidneys to cleanse the blood and achieve hydroelectrolytic balance. Worldwide, nearly 1.5 million people need RRT, and the incidence of CKD has increased significantly over the last decades. Diabetes and hypertension are among the leading causes of end stage renal disease, although autoimmunity, renal atherosclerosis, certain infections, drugs and toxins, obstruction of the urinary tract, genetic alterations, and other insults may initiate the disease by damaging the glomerular, tubular, vascular or interstitial compartments of the kidneys. In all cases, CKD eventually compromises all these structures and gives rise to a similar phenotype regardless of etiology. This review describes with an integrative approach the pathophysiological process of tubulointerstitial, glomerular and renovascular diseases, and makes emphasis on the key cellular and molecular events involved. It further analyses the key mechanisms leading to a merging phenotype and pathophysiological scenario as etiologically distinct diseases progress. Finally clinical implications and future experimental and therapeutic perspectives are discussed.

  6. Contactless two-stage solar concentrators for tubular absorber

    NASA Astrophysics Data System (ADS)

    Benitez, Pablo; Minano, Juan C.; Garcia, Raphael; Mohedano Arroyo, Ruben

    1997-10-01

    Two new types of two-mirror solar concentrator for tubular receiver, the snail concentrator and the helmet concentrator , are presented. The main feature of these concentrators is that they have a sizable gap between the secondary mirror and the absorber, and they still achieve concentrations close to the thermodynamic limit with high collection efficiencies. This characteristic makes them unique and, on the contrary to the present two-stage designs, allows for the location of the secondary outside the evacuated tube. One of the differences between the snail and the helmet concentrators is that the last is symmetric (as the conventional parabolic trough) but the first is not. For an acceptance angle of (alpha) equals +/- 0.73 degs and a collection efficiency of 96.8% (i.e. 3.2% of the rays incident on the primary mirror within the acceptance angle are rejected), the snail concentrator and the helmet concentrator achieve an average flux concentration of 91.1% and 72.8% of the thermodynamic limit, respectively. The gap between the absorber and the secondary mirror is 6.8 and 12.1 times the absorber radius for each concentrator. Moreover, both concentrators have also high rim angles of the primary mirror: +/- 86.2 degs (helmet) and 3.1 - 98.8 degs (snail). This is of interest for a good mechanical stability of the collector.

  7. Tubular microbial fuel cells for efficient electricity generation.

    PubMed

    Rabaey, Korneel; Clauwaert, Peter; Aelterman, Peter; Verstraete, Willy

    2005-10-15

    A tubular, single-chambered, continuous microbial fuel cell (MFC) that generates high power outputs using a granular graphite matrix as the anode and a ferricyanide solution as the cathode is described. The maximal power outputs obtained were 90 and 66 W m(-3) net anodic compartment (NAC) (48 and 38 W m(-3) total anodic compartment (TAC)) for feed streams based on acetate and glucose, respectively, and 59 and 48 W m(-3) NAC for digester effluent and domestic wastewater, respectively. For acetate and glucose, the total Coulombic conversion efficiencies were 75 +/- 5% and 59 +/- 4%, respectively, at loading rates of 1.1 kg chemical oxygen demand m(-3) NAC volume day(-1). When wastewater was used, of the organic matter effectively removed (i.e., 22% at a loading of 2 kg organic matter m(-3) NAC day(-1)), up to 96% was converted to electricity on a Coulombic basis. The lower overall efficiency of the wastewater-treating reactors is related to the presence of nonreadily biodegradable organics and the interference of alternative electron acceptors such as sulfate present in the wastewater. To further improve MFCs, focus has to be placed on the enhanced conversion of nonrapidly biodegradable material and the better directing of the anode flow toward the electrode instead of to alternative electron acceptors. Also the use of sustainable, open-air cathodes is a critical issue for practical implementation.

  8. Crystalline Membranes

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  9. Porous membrane utilization in plant nutrient delivery

    NASA Technical Reports Server (NTRS)

    Dreschel, T. W.; Hinkle, C. R.; Prince, R. P.; Knott, W. M., III

    1987-01-01

    A spacecraft hydroponic plant growth unit of tubular configuration, employing a microporous membrane as a capilary interface between plant roots and a nutrient solution, is presented. All three of the experimental trials undertaken successfully grew wheat from seed to harvest. Attention is given to the mass/seed, number of seeds/head, ratio of seed dry mass to total plant dry mass, production of tillers, and mass of seed/plant. Dry matter production is found to be reduced with increasing suction pressure; this is true for both average seed and average total dry matter/plant. This may be due to a reduction in water and nutrient availability through the microporous membrane.

  10. Hypokalemic quadriparesis and rhabdomyolysis as a rare presentation of distal renal tubular acidosis

    PubMed Central

    Ahmad Bhat, Manzoor; Ahmad Laway, Bashir; Mustafa, Farhat; Shafi Kuchay, Mohammad; Mubarik, Idrees; Ahmad Palla, Nazir

    2014-01-01

    Distal renal tubular acidosis is a syndrome of abnormal urine acidification and is characterized by hyperchloremic metabolic acidosis, hypokalemia, hypercalciurea, nephrocalcinosis and nephrolithiasis. Despite the presence of persistent hypokalemia, acute muscular paralysis is rarely encountered in males. Here, we will report an eighteen year old male patient who presented with flaccid quadriparesis and was subsequently found to have rhabdomyolysis, severe short stature, skeletal deformities and primary distal renal tubular acidosis. PMID:25250276

  11. Renal tubular dysfunction presenting as recurrent hypokalemic periodic quadriparesis in systemic lupus erythematosus

    PubMed Central

    Prasad, D.; Agarwal, D.; Malhotra, V.; Beniwal, P.

    2014-01-01

    We report recurrent hypokalemic periodic quadriparesis in a 30-year-old woman. Patient had also symptoms of multiple large and small joint pain, recurrent oral ulceration, photosensitivity and hair loss that were persisting since last 6 months and investigations revealed systemic lupus erythematosus (SLE) with distal tubular acidosis. Our patient was successfully treated with oral potassium chloride, sodium bicarbonate, hydroxychloroquine and a short course of steroids. Thus, tubular dysfunction should be carefully assessed in patients with SLE. PMID:25249723

  12. [Forensic medical characteristic of sawed injuries inflicted to the long tubular bones by a power jigsaw].

    PubMed

    Nazarov, Iu V; Tolmachev, I A

    2013-01-01

    The main aspects of investigations devoted to forensic medical characteristic of sawed injuries inflicted to the long tubular bones by a power jigsaw are considered. The mathematical model has been developed making it possible to determine the frequency of backward and forward movements of the jigsaw blade from the morphological features of the injuries to long tubular bones of man and to estimate the sawing rate for the further identification of the instrument of crime.

  13. Design and performance of tubular flat-plate solid oxide fuel cell

    SciTech Connect

    Matsushima, T.; Ikeda, D.; Kanagawa, H.

    1996-12-31

    With the growing interest in conserving the environmental conditions, much attention is being paid to Solid Oxide Fuel Cell (SOFC), which has high energy-conversion efficiency. Many organizations have conducted studies on tubular and flat type SOFCs. Nippon Telegraph and Telephone Corporation (NTT) has studied a combined tubular flat-plate SOFC, and already presented the I-V characteristics of a single cell. Here, we report the construction of a stack of this SOFC cell and successful generation tests results.

  14. Closed membrane shapes with attached BAR domains subject to external force of actin filaments.

    PubMed

    Mesarec, Luka; Góźdź, Wojciech; Iglič, Veronika Kralj; Kralj, Samo; Iglič, Aleš

    2016-05-01

    Membrane deformations induced by attached BAR superfamily domains could trigger or facilitate the growth of plasma membrane protrusions. The BAR domain family consists of BAR, F-BAR and I-BAR domains, each enforcing a different local curvature when attached to the membrane surface. Our theoretical study mainly focuses on the role of I-BAR in the membrane tubular deformations generated or stabilised by actin filaments. The influence of the area density of membrane attached BAR domains and their intrinsic curvature on the closed membrane shapes (vesicles) was investigated numerically. We derived an analytical approximative expression for the critical relative area density of BARs at which the membrane tubular protrusions on vesicles are most prominent. We have shown that the BARs with a higher intrinsic curvature induce thinner and longer cylindrical protrusions. The average orientation of the membrane attached BARs is altered when the vesicle shape is subjected to external force of growing actin rod-like structure inside a vesicle. The average orientation angle of membrane attached BARs may indicate whether the actin filaments are just stabilising the protrusion or generating it by stretching the vesicle.

  15. Biological membranes

    PubMed Central

    Watson, Helen

    2015-01-01

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

  16. Inner Surface Chirality of Single-Handed Twisted Carbonaceous Tubular Nanoribbons.

    PubMed

    Liu, Dan; Li, Baozong; Guo, Yongmin; Li, Yi; Yang, Yonggang

    2015-11-01

    Single-handed twisted 4,4'-biphenylene-bridged polybissilsesquioxane tubular nanoribbons and single-layered nanoribbons were prepared by tuning the water/ethanol volume ratio in the reaction mixture at pH = 11.6 through a supramolecular templating approach. The single-layered nanoribbons were formed by shrinking tubular nanoribbons after the removal of the templates. In addition, solvent-induced handedness inversion was achieved. The handedness of the polybissilsesquioxanes could be controlled by changing the ethanol/water volume ratio in the reaction mixture. After carbonization at 900 °C for 4.0 h and removal of silica, single-handed twisted carbonaceous tubular nanoribbons and single-layered nanoribbons with micropores in the walls were obtained. X-ray diffraction and Raman spectroscopy analyses indicated that the carbon is predominantly amorphous. The circular dichroism spectra show that the twisted tubular nanoribbons exhibit optical activity, while the twisted single-layered nanoribbons do not. The results shown here indicate that chirality is transferred from the organic self-assemblies to the inner surfaces of the 4,4'-biphenylene-bridged polybissilsesquioxane tubular nanoribbons and subsequently to those of the carbonaceous tubular nanoribbons.

  17. Changes in Proximal and Distal Tubular Reabsorption Produced by Rapid Expansion of Extracellular Fluid*

    PubMed Central

    Hayslett, John P.; Kashgarian, Michael; Epstein, Franklin H.

    1967-01-01

    Acute infusions of isotonic saline in the rat cause an increase in glomerular filtration rate and in the excretion of salt and water. The kidney swells, due to expansion of tubular and interstitial volume. Despite the increase in tubular diameter, transit time through the proximal tubules and loops of Henle is decreased, presumably owing to a greatly accelerated rate of tubular flow. Proximal tubular reabsorption, measured in blocked tubules, is inhibited in a way that cannot be ascribed to changes in tubular diameter. The prolongation of proximal reabsorptive half-time is not affected by the administration of aldosterone. It occurs equally in rats chronically loaded with or deprived of salt, and it is therefore not likely that it is influenced by the renal content of renin. In contrast, reabsorption from the distal convoluted tubule is enhanced by saline infusion. This change is observed in segments of tubules blocked with oil and isolated from their glomeruli and thus appears to occur independently of changes in glomerular filtration or tubular flow. Images PMID:6027087

  18. Human embryonic stem cells differentiate into functional renal proximal tubular-like cells.

    PubMed

    Narayanan, Karthikeyan; Schumacher, Karl M; Tasnim, Farah; Kandasamy, Karthikeyan; Schumacher, Annegret; Ni, Ming; Gao, Shujun; Gopalan, Began; Zink, Daniele; Ying, Jackie Y

    2013-04-01

    Renal cells are used in basic research, disease models, tissue engineering, drug screening, and in vitro toxicology. In order to provide a reliable source of human renal cells, we developed a protocol for the differentiation of human embryonic stem cells into renal epithelial cells. The differentiated stem cells expressed markers characteristic of renal proximal tubular cells and their precursors, whereas markers of other renal cell types were not expressed or expressed at low levels. Marker expression patterns of these differentiated stem cells and in vitro cultivated primary human renal proximal tubular cells were comparable. The differentiated stem cells showed morphological and functional characteristics of renal proximal tubular cells, and generated tubular structures in vitro and in vivo. In addition, the differentiated stem cells contributed in organ cultures for the formation of simple epithelia in the kidney cortex. Bioreactor experiments showed that these cells retained their functional characteristics under conditions as applied in bioartificial kidneys. Thus, our results show that human embryonic stem cells can differentiate into renal proximal tubular-like cells. Our approach would provide a source for human renal proximal tubular cells that are not affected by problems associated with immortalized cell lines or primary cells.

  19. Comparison between small radiation therapy electron beams collimated by Cerrobend and tubular applicators.

    PubMed

    Di Venanzio, Cristina; Marinelli, Marco; Tonnetti, Alessia; Verona-Rinati, Gianluca; Bagalà, Paolo; Falco, Maria Daniela; Guerra, Antonio Stefano; Pimpinella, Maria

    2015-01-08

    The purpose of this study was to compare the dosimetric properties of small field electron beams shaped by circular Cerrobend blocks and stainless steel tubular applicators. Percentage depth dose curves, beam profiles, and output factors of small-size circular fields from 2 to 5 cm diameter, obtained either by tubular applicators and Cerrobend blocks, were measured for 6, 10, and 15 MeV electron beam energies. All measurements were performed using a PTW microDiamond 60019 premarket prototype. An overall similar behavior between the two collimating systems can be observed in terms of PDD and beam profiles. However, Cerrobend collimators produce a higher bremsstrahlung background under irradiation with high-energy electrons. In such irradiation condition, larger output factors are observed for tubular applicators. Similar dosimetric properties are observed using circular Cerrobend blocks and stainless steel tubular applicators at lower beam energies. However, Cerrobend collimators allow the delivery of specific beam shapes, conformed to the target area. On the other hand, in high-energy irradiation conditions, tubular applicators produce a lower bremsstrahlung contribution, leading to lower doses outside the target volume. In addition, the higher output factors observed at high energies for tubular applicators lead to reduced treatment times.

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

    NASA Technical Reports Server (NTRS)

    Richter, R.

    1982-01-01

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

  1. Membrane-based energy efficient dewatering of microalgae in biofuels production and recovery of value added co-products.

    PubMed

    Bhave, Ramesh; Kuritz, Tanya; Powell, Lawrence; Adcock, Dale

    2012-05-15

    The objective of this paper is to describe the use of membranes for energy efficient biomass harvesting and dewatering. The dewatering of Nannochloropsis sp. was evaluated with polymeric hollow fiber and tubular inorganic membranes to demonstrate the capabilities of a membrane-based system to achieve microalgal biomass of >150 g/L (dry wt.) and ∼99% volume reduction through dewatering. The particle free filtrate containing the growth media is suitable for recycle and reuse. For cost-effective processing, hollow fiber membranes can be utilized to recover 90-95% media for recycle. Tubular membranes can provide additional media and water recovery to achieve target final concentrations. Based on the operating conditions used in this study and taking into scale-up considerations, an integrated hollow fiber-tubular membrane system can process microalgal biomass with at least 80% lower energy requirement compared to traditional processes. Backpulsing was found to be an effective flux maintenance strategy to minimize flux decline at high biomass concentration. An effective chemical cleaning protocol was developed for regeneration of fouled membranes.

  2. Membrane-Based Energy Efficient Dewatering of Microalgae in Biofuels Production and Recovery of Value Added Co-Products

    SciTech Connect

    Bhave, Ramesh R; Kuritz, Tanya; Powell, Lawrence E; Adcock, Kenneth Dale

    2012-01-01

    The objective of this paper is to describe the use of membranes for energy efficient biomass harvesting and dewatering. We have evaluated the dewatering of Nannochloropsis sp. with polymeric hollow fiber and tubular inorganic membranes to demonstrate the capabilities of a membrane-based system to achieve microalgal biomass of >150 g/L (dry wt.) and ~99% volume reduction through dewatering. The particle free filtrate containing the growth media is suitable for recycle and reuse. For cost-effective processing, hollow fiber membranes can be utilized to recover 90-95% media for recycle. Tubular membranes can provide additional media and water recovery to achieve target final concentrations. Based on the operating conditions used in this study and taking into scale-up considerations, it can be shown that an integrated hollow fiber-tubular membrane system can process microalgal biomass with at least 80% lower energy requirement compared to traditional processes. Backpulsing was found to be an effective flux maintenance strategy to minimize flux decline at high biomass concentration. An effective chemical cleaning protocol was developed for regeneration of fouled membranes.

  3. A reduced graphene oxide nanofiltration membrane intercalated by well-dispersed carbon nanotubes for drinking water purification.

    PubMed

    Chen, Xianfu; Qiu, Minghui; Ding, Hao; Fu, Kaiyun; Fan, Yiqun

    2016-03-14

    In this study, we report a promising rGO-CNT hybrid nanofiltration (NF) membrane that was fabricated by loading reduced graphene oxide that was intercalated with carbon nanotubes (rGO-CNTs) onto an anodic aluminum oxide (AAO) microfiltration membrane via a facile vacuum-assisted filtration process. To create this NF membrane, the CNTs were first dispersed using block copolymers (BCPs); the effects of the types and contents of BCPs used on the dispersion of CNTs have been investigated. The as-prepared rGO-CNT hybrid NF membranes were then used for drinking water purification to retain the nanoparticles, dyes, proteins, organophosphates, sugars, and particularly humic acid. Experimentally, it is shown that the rGO-CNT hybrid NF membranes have high retention efficiency, good permeability and good anti-fouling properties. The retention was above 97.3% even for methyl orange (327 Da); for other objects, the retention was above 99%. The membrane's permeability was found to be as high as 20-30 L m(-2) h(-1) bar(-1). Based on these results, we can conclude that (i) the use of BCPs as a surfactant can enhance steric repulsion and thus disperse CNTs effectively; (ii) placing well-dispersed 1D CNTs within 2D graphene sheets allows an uniform network to form, which can provide many mass transfer channels through the continuous 3D nanostructure, resulting in the high permeability and separation performance of the rGO-CNT hybrid NF membranes.

  4. Bioinspired Bifunctional Membrane for Efficient Clean Water Generation.

    PubMed

    Liu, Yang; Lou, Jinwei; Ni, Mengtian; Song, Chengyi; Wu, Jianbo; Dasgupta, Neil P; Tao, Peng; Shang, Wen; Deng, Tao

    2016-01-13

    Solving the problems of water pollution and water shortage is an urgent need for the sustainable development of modern society. Different approaches, including distillation, filtration, and photocatalytic degradation, have been developed for the purification of contaminated water and the generation of clean water. In this study, we explored a new approach that uses solar light for both water purification and clean water generation. A bifunctional membrane consisting of a top layer of TiO2 nanoparticles (NPs), a middle layer of Au NPs, and a bottom layer of anodized aluminum oxide (AAO) was designed and fabricated through multiple filtration processes. Such a design enables both TiO2 NP-based photocatalytic function and Au NP-based solar-driven plasmonic evaporation. With the integration of these two functions into a single membrane, both the purification of contaminated water through photocatalytic degradation and the generation of clean water through evaporation were demonstrated using simulated solar illumination. Such a demonstration should also help open up a new strategy for maximizing solar energy conversion and utilization.

  5. Design, construction and evaluation of solarized airlift tubular photobioreactor

    NASA Astrophysics Data System (ADS)

    Bahadur, A.; Zubair, M.; Khan, M. B.

    2013-06-01

    An innovative photobioreactor is developed for growing algae in simulated conditions. The proposed design comprises of a continuous tubular irradiance loop and air induced liquid circulation with gas separation through air lift device. The unique features of air lift system are to ensure the shear free circulation of sensitive algal culture and induce light/dark cycles to the photosynthetic micro-organisms. The design strategy employs to model and construct a 20-liter laboratory scale unit using Boro-silicate glass tubing. The material is selected to ensure maximum photon transmission. All components of the device are designed to have flexibility to be replaced with an alternative design, providing fair chance of modification for future investigators. The principles of fluid mechanics are applied to describe geometrical attributes of the air lift system. Combination of LEDs and Florescent tube lights (Warm white) were used to illuminate the photosynthesis reaction area providing a possibility to control both illumination duration and light intensity. 200 Watt Solar PV system is designed to power up the device which included air pump (100 Watt) and illumination system (100 Watt). Algal strain Chlorella sp was inoculated in photobioreactor which was sparged with air and carbon dioxide. The growth was sustained in the batch mode with daily monitoring of temperature, pH and biomass concentration. The novel photobioreactor recorded a maximum experimental average yield of 0.65 g/l.day (11.3 g/m2.day) as compared to theoretical modeled yield of 0.82 g/l.day (14.26 g/m2.day), suggesting the device can be efficiently and cost-effectively employed in the production of algal biomass for biofuels, concomitantly mitigating CO2.

  6. Perfluorooctanesulfonate Mediates Renal Tubular Cell Apoptosis through PPARgamma Inactivation

    PubMed Central

    Chou, Hsiu-Chu; Chang, Chih-Cheng; Lo, Hau-Yin; Juan, Shu-Hui

    2016-01-01

    Perfluorinated chemicals (PFCs) are ubiquitously distributed in the environments including stainless pan-coating, raincoat, fire extinguisher, and semiconductor products. The PPAR family has been shown to contribute to the toxic effects of PFCs in thymus, immune and excretory systems. Herein, we demonstrated that perfluorooctanesulfonate (PFOS) caused cell apoptosis through increasing ratio of Bcl-xS/xL, cytosolic cytochrome C, and caspase 3 activation in renal tubular cells (RTCs). In addition, PFOS increased transcription of inflammatory cytokines (i.e., TNFα, ICAM1, and MCP1) by NFκB activation. Conversely, PFOS reduced the mRNA levels of antioxidative enzymes, such as glutathione peroxidase, catalase, and superoxide dismutase, as a result of reduced PPARγ transactivational activity by using reporter and chromatin immuoprecipitation (ChIP) assays. PFOS reduced the protein interaction between PPARγ and PPARγ coactivator-1 alpha (PGC1α) by PPARγ deacetylation through Sirt1 upregulation, of which the binding of PPARγ and PGC1α to a peroxisome proliferator response element (PPRE) in the promoter regions of these antioxidative enzymes was alleviated in the ChIP assay. Furthermore, Sirt1 also deacetylated p53 and then increased the binding of p53 to Bax, resulting in increased cytosolic cytochrome C. The effect of PPARγ inactivation by PFOS was validated using the PPARγ antagonist GW9662, whereas the adverse effects of PFOS were prevented by PPARγ overexpression and activators, rosiglitozone and L-carnitine, in RTCs. The in vitro finding of protective effect of L-carnitine was substantiated in vivo using Balb/c mice model subjected to PFOS challenge. Altogether, we provide in vivo and in vitro evidence for the protective mechanism of L-carnitine in eliminating PFOS-mediated renal injury, at least partially, through PPARγ activation. PMID:27171144

  7. The Dynamical Evolution of A Tubular Leonid Persistent Train

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Nugent, David; Plane, John M. C.; DeVincenzi, Donald L. (Technical Monitor)

    2000-01-01

    The dynamical evolution of the persistent train of a bright Leonid meteor was examined for evidence of the source of the luminosity and the physical conditions in the meteor path. The train consisted of two parallel somewhat diffuse luminous tracks, interpreted as the walls of a tube. A general lack of wind shear along the trail allowed these structures to remain intact for nearly 200 s, from which it was possible to determine that the tubular structure expanded at a near constant 10.5 m/s, independent of altitude between 86 and 97 km. An initial fast decrease of train intensity below 90 km was followed by an increase in intensity and then a gradual decrease at longer times, whereas at high attitudes the integrated intensity was nearly constant with time. These results are compared to a model that describes the dynamical evolution of the train by diffusion, following an initial rapid expansion of the hot gaseous trail behind the meteoroid. The train luminosity is produced by O ((sup 1)S) emission at 557 nm, driven by elevated atomic O levels produced by the meteor impact, as well as chemiluminescent reactions of the ablated metals Na and Fe with O3. Ozone is rapidly removed within the train, both by thermal decomposition and catalytic destruction by the metallic species. Hence, the brightest emission occurs at the edge of the train between outwardly diffusing metallic species and inwardly diffusing O3. Although the model is able to account plausibly for a number of characteristic features of the train evolution, significant discrepancies remain that cannot easily be resolved.

  8. Effect of air flow on tubular solar still efficiency

    PubMed Central

    2013-01-01

    Background An experimental work was reported to estimate the increase in distillate yield for a compound parabolic concentrator-concentric tubular solar still (CPC-CTSS). The CPC dramatically increases the heating of the saline water. A novel idea was proposed to study the characteristic features of CPC for desalination to produce a large quantity of distillate yield. A rectangular basin of dimension 2 m × 0.025 m × 0.02 m was fabricated of copper and was placed at the focus of the CPC. This basin is covered by two cylindrical glass tubes of length 2 m with two different diameters of 0.02 m and 0.03 m. The experimental study was operated with two modes: without and with air flow between inner and outer tubes. The rate of air flow was fixed throughout the experiment at 4.5 m/s. On the basis of performance results, the water collection rate was 1445 ml/day without air flow and 2020 ml/day with air flow and the efficiencies were 16.2% and 18.9%, respectively. Findings The experimental study was operated with two modes: without and with air flow between inner and outer tubes. The rate of air flow was fixed throughout the experiment at 4.5 m/s. Conclusions On the basis of performance results, the water collection rate was 1445 ml/day without air flow and 2020 ml/day with air flow and the efficiencies were 16.2% and 18.9%, respectively. PMID:23587020

  9. The Dynamical Evolution of a Tubular Leonid Persistent Train

    NASA Astrophysics Data System (ADS)

    Jenniskens, Peter; Nugent, David; Plane, John M. C.

    The dynamical evolution of the persistent train of a bright Leonid meteor was examined for evidence of the source of the luminosity and the physical conditions in the meteor path. The train consisted of two parallel somewhat diffuse luminous tracks, interpreted as the walls of a tube. A general lack of wind shear along the trail allowed these structures to remain intact for nearly 200 s, from which it was possible to determine that the tubular structure expanded at a near constant 10.5 ms^-1, independent of altitude between 86 and 97 km. An initial fast decrease of train intensity below 90 km was followed by an increase in intensity and then a gradual decrease at longer times, whereas at high altitudes the integrated intensity was nearly constant with time. These results are compared to a model that describes the dynamical evolution of the train by diffusion, following an initial rapid expansion of the hot gaseous trail behind the meteoroid. The train luminosity is produced by O (^1S) emission at 557 nm, driven by elevated atomic O levels produced by the meteor impact, as well as chemiluminescent reactions of the ablated metals Na and Fe with O_3. Ozone is rapidly removed within the train, both by thermal decomposition and catalytic destruction by the metallic species. Hence, the brightest emission occurs at the edge of the train between outwardly diffusing metallic species and inwardly diffusing O_3. Although the model is able to account plausibly for a number of characteristic features of the train evolution, significant discrepancies remain that cannot casily be resolved.

  10. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT - REMOVAL OF PRECURSORS TO DISINFECTION BY-PRODUCTS IN DRINKING WATER, PCI MEMBRANE SYSTEMS FYNE PROCESS MODEL ROP 1434 WITH AFC-30 NANOFILTRATON AT BARROW, AK - NSF 00/19/EPADW395

    EPA Science Inventory

    Equipment testing and verification of PCI Membrane Systems Inc. Fyne Process nanofiltraton systems Model ROP 1434 equipped with a C10 module containing AFC-30 tubular membranes was conducted from 3/16-5/11/2000 in Barrow, AS. The source water was a moderate alkalinity, moderately...

  11. Urinary excretion of beta 2-glycoprotein-1 (apolipoprotein H) and other markers of tubular malfunction in "non-tubular" renal disease.

    PubMed Central

    Flynn, F. V.; Lapsley, M.; Sansom, P. A.; Cohen, S. L.

    1992-01-01

    AIM: To determine whether urinary beta 2-glycoprotein-1 assays can provide improved discrimination between chronic renal diseases which are primarily of tubular or glomerular origin. METHODS: Urinary beta 2-glycoprotein-1, retinol-binding protein, alpha 1-microglobulin, beta 2-microglobulin, N-acetyl-beta-D-glucosa-minidase and albumin were measured in 51 patients with primary glomerular disease, 23 with obstructive nephropathy, and 15 with polycystic kidney disease, and expressed per mmol of creatinine. Plasma beta 2-glycoprotein-1 was assayed in 52 patients and plasma creatinine in all 89. The findings were compared between the diagnostic groups and with previously published data relating to primary tubular disorders. RESULTS: All 31 patients with plasma creatinine greater than 200 mumol/l excreted increased amounts of beta 2-glycoprotein-1, retinol-binding protein, and alpha 1-microglobulin, and 29 had increased N-acetyl-beta-D-glucosaminidase; the quantities were generally similar to those found in comparable patients with primary tubular pathology. Among 58 with plasma creatinine concentrations under 200 mumol/l, increases in beta 2-glycoprotein-1, retinol-binding protein, and alpha 1-microglobulin excretion were less common and much smaller, especially in those with obstructive nephropathy and polycystic disease. The ratios of the excretion of albumin to the other proteins provided the clearest discrimination between the patients with glomerular or tubular malfunction, but an area of overlap was present which embraced those with obstructive nephropathy and polycystic disease. CONCLUSIONS: Increased excretion of beta 2-glycoprotein-1 due to a raised plasma concentration or diminution of tubular reabsorption, or both, is common in all the forms of renal disease investigated, and both plasma creatinine and urinary albumin must be taken into account when interpreting results. Ratios of urinary albumin: beta 2-glycoprotein-1 greater than 1000 are highly suggestive

  12. Elimination of etimicin in rat kidneys and alterations of its cytotoxicity to tubular epithelial cells.

    PubMed

    Li, Z-D; Zhang, X-L; Yi, N; Zhang, F-C

    2015-05-01

    Etimicin (ETM) can accumulate in kidneys and cause tubular epithelial cell cytotoxicity. This article aims to study ETM elimination in kidneys and its nephrotoxicity, apoptosis, and histopathological insults of renal tubular epithelial cells, after repeated administration. A total of 36 rats were randomly divided into ETM-treated group and vehicle control group. Rats in ETM-treated group were treated intraperitoneally (i.p.) with 100 mg/kg/day ETM and rats in control group received physiological saline (i.p.) for 5 consecutive days. Determination of ETM concentrations accumulated in rat kidneys was carried out by high-performance liquid chromatography on the basis of derivatization with o-phthalaldehyde and by ultraviolet detector. Apoptotic renal tubular epithelial cells were identified by a terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick-end labeling assay. Histopathological insults in kidneys were evaluated by hematoxylin and eosin staining. On day 1 after cessation of ETM administration, the accumulation concentration was 347.50 ± 193.30 μg/g tissue; on day 15, ETM concentration became 16.71 ± 9.99 μg/g tissue. Elimination half-life of ETM in rat kidney was about 3.05 days. Apoptotic renal tubular epithelial cells induced by etimicin was recovered gradually from 1544 ± 138 n/mm(2) on day 1 to 716 ± 208 n/mm(2) on day 15. Histopathological damage was also gradually recovered from vacuolation of tubular epithelial cells as well as renal tubular edema on days 1, 3, and 7 to nearly normal on day 15. From these results, we concluded that renal tubular epithelial cell cytotoxicity induced by ETM can gradually restore with its decreasing concentration in rat kidneys.

  13. Metamaterial membranes

    NASA Astrophysics Data System (ADS)

    Restrepo-Flórez, Juan Manuel; Maldovan, Martin

    2017-01-01

    We introduce a new class of metamaterial device to achieve separation of compounds by using coordinate transformations and metamaterial theory. By rationally designing the spatial anisotropy for mass diffusion, we simultaneously concentrate different compounds in different spatial locations, leading to separation of mixtures across a metamaterial membrane. The separation of mixtures into their constituent compounds is critically important in biophysics, biomedical, and chemical applications. We present a practical case where a mixture of oxygen and nitrogen diffusing through a polymeric planar matrix is separated. This work opens doors to new paradigms in membrane separations via coordinate transformations and metamaterials by introducing novel properties and unconventional mass diffusion phenomena.

  14. Multicomponent Transport through Realistic Zeolite Membranes: Characterization & Transport in Nanoporous Networks

    SciTech Connect

    William C. Conner

    2007-08-02

    These research studies focused on the characterization and transport for porous solids which comprise both microporosity and mesoporosity. Such materials represent membranes made from zeolites as well as for many new nanoporous solids. Several analytical sorption techniques were developed and evaluated by which these multi-dimensional porous solids could be quantitatively characterized. Notably an approach by which intact membranes could be studied was developed and applied to plate-like and tubular supported zeolitic membranes. Transport processes were studied experimentally and theoretically based on the characterization studies.

  15. Mitotic Golgi partitioning is driven by the membrane-fissioning protein CtBP3/BARS.

    PubMed

    Hidalgo Carcedo, Cristina; Bonazzi, Matteo; Spanò, Stefania; Turacchio, Gabriele; Colanzi, Antonino; Luini, Alberto; Corda, Daniela

    2004-07-02

    Organelle inheritance is an essential feature of all eukaryotic cells. As with other organelles, the Golgi complex partitions between daughter cells through the fission of its membranes into numerous tubulovesicular fragments. We found that the protein CtBP3/BARS (BARS) was responsible for driving the fission of Golgi membranes during mitosis in vivo. Moreover, by in vitro analysis, we identified two stages of this Golgi fragmentation process: disassembly of the Golgi stacks into a tubular network, and BARS-dependent fission of these tubules. Finally, this BARS-induced fission of Golgi membranes controlled the G2-to-prophase transition of the cell cycle, and hence cell division.

  16. Osteomalacia complicating renal tubular acidosis in association with Sjogren's syndrome.

    PubMed

    El Ati, Zohra; Fatma, Lilia Ben; Boulahya, Ghada; Rais, Lamia; Krid, Madiha; Smaoui, Wided; Maiz, Hedi Ben; Beji, Soumaya; Zouaghi, Karim; Moussa, Fatma Ben

    2014-09-01

    Renal involvement in Sjogren's syndrome (SS) is not uncommon and may precede other complaints. Tubulointerstitial nephritis is the most common renal disease in SS and may lead to renal tubular acidosis (RTA), which in turn may cause osteomalacia. Nevertheless, osteomalacia rarely occurs as the first manifestation of a renal tubule disorder due to SS. We herewith describe a 43-year-old woman who was admitted to our hospital for weakness, lumbago and inability to walk. X-ray of the long bones showed extensive demineralization of the bones. Laboratory investigations revealed chronic kidney disease with serum creatinine of 2.3 mg/dL and creatinine clearance of 40 mL/min, hypokalemia (3.2 mmol/L), hypophosphatemia (0.4 mmol/L), hypocalcemia (2.14 mmol/L) and hyperchloremic metabolic acidosis (chlorine: 114 mmol/L; alkaline reserve: 14 mmol/L). The serum alkaline phosphatase levels were elevated. The serum levels of 25-hydroxyvitamin D and 1,25-dihydroxy vitamin D were low and borderline low, respectively, and the parathyroid hormone level was 70 pg/L. Urinalysis showed inappropriate alkaline urine (urinary PH: 7), glycosuria with normal blood glucose, phosphaturia and uricosuria. These values indicated the presence of both distal and proximal RTA. Our patient reported dryness of the mouth and eyes and Schirmer's test showed xerophthalmia. An accessory salivary gland biopsy showed changes corresponding to stage IV of Chisholm and Masson score. Kidney biopsy showed diffuse and severe tubulo-interstitial nephritis with dense lymphoplasmocyte infiltrates. Sicca syndrome and renal interstitial infiltrates indicated SS as the underlying cause of the RTA and osteomalacia. The patient received alkalinization, vitamin D (Sterogyl ®), calcium supplements and steroids in an initial dose of 1 mg/kg/day, tapered to 10 mg daily. The prognosis was favorable and the serum creatinine level was 1.7 mg/dL, calcium was 2.2 mmol/L and serum phosphate was 0.9 mmol/L.

  17. Cellular Uptake and Localization of Polymyxins in Renal Tubular Cells Using Rationally Designed Fluorescent Probes

    PubMed Central

    Yun, Bo; Azad, Mohammad A. K.; Nowell, Cameron J.; Nation, Roger L.; Thompson, Philip E.; Roberts, Kade D.

    2015-01-01

    Polymyxins are cyclic lipopeptide antibiotics that serve as a last line of defense against Gram-negative bacterial superbugs. However, the extensive accumulation of polymyxins in renal tubular cells can lead to nephrotoxicity, which is the major dose-limiting factor in clinical use. In order to gain further insights into the mechanism of polymyxin-induced nephrotoxicity, we have rationally designed novel fluorescent polymyxin probes to examine the localization of polymyxins in rat renal tubular (NRK-52E) cells. Our design strategy focused on incorporating a dansyl fluorophore at the hydrophobic centers of the polymyxin core structure. To this end, four novel regioselectively labeled monodansylated polymyxin B probes (MIPS-9541, MIPS-9542, MIPS-9543, and MIPS-9544) were designed, synthesized, and screened for their antimicrobial activities and apoptotic effects against rat kidney proximal tubular cells. On the basis of the assessment of antimicrobial activities, cellular uptake, and apoptotic effects on renal tubular cells, incorporation of a dansyl fluorophore at either position 6 or 7 (MIPS-9543 and MIPS-9544, respectively) of the polymyxin core structure appears to be an appropriate strategy for generating representative fluorescent polymyxin probes to be utilized in intracellular imaging and mechanistic studies. Furthermore, confocal imaging experiments utilizing these probes showed evidence of partial colocalization of the polymyxins with both the endoplasmic reticulum and mitochondria in rat renal tubular cells. Our results highlight the value of these new fluorescent polymyxin probes and provide further insights into the mechanism of polymyxin-induced nephrotoxicity. PMID:26392495

  18. Polydopamine-coated open tubular column for the separation of proteins by capillary electrochromatography.

    PubMed

    Xiao, Xing; Wang, Wentao; Chen, Jia; Jia, Li

    2015-08-01

    The separation and determination of proteins in food is an important aspect in food industry. Inspired by the self-polymerization of dopamine under alkaline conditions and the natural adhesive properties of polydopamine, in this paper, a simple and economical method was developed for the preparation of polydopamine-coated open tubular column, in which ammonium persulfate was used as the source of oxygen to induce and facilitate the polymerization of dopamine to form polydopamine. In comparison with a naked fused-silica capillary, the direction and magnitude of the electro-osmotic flow of the as-prepared polydopamine-coated open tubular column could be manipulated by varying the pH values of background solutions due to the existence of amine and phenolic hydroxyl groups on polydopamine coating. The surface morphology of the polydopamine-coated open tubular column was studied by scanning electron microscopy, and the thickness of polydopamine coating was 106 nm. The performance of the polydopamine-coated open tubular column was validated by analysis of proteins. The relative standard deviations of migration times of proteins representing run-to-run, day-to-day, and column-to-column were less than 3.5%. In addition, the feasibility of the polydopamine-coated open tubular column for real samples was verified by the separation of proteins in chicken egg white and pure milk.

  19. Tubular Dysfunction Mimicking Dent's Disease in 2 Infants Born with Extremely Low Birth Weight

    PubMed Central

    Awazu, Midori; Arai, Mie; Ohashi, Shoko; Takahashi, Hirotaka; Sekine, Takashi; Ikeda, Kazushige

    2017-01-01

    Two preterm infants, with extremely low birth weight born at gestational weeks 24 and 25, showed generalized proximal tubular dysfunction during their stay in the neonatal intensive care unit, including glucosuria, low molecular weight proteinuria, phosphaturia, uricosuria, enzymuria (elevated urine N-acetyl-β-D-glucosaminidase), panaminoaciduria, and hypercalciuria, associated with renal calcification. Renal tubular acidosis was not present in either patient. DNA mutation analysis for Dent's disease, performed in patient 1, was negative. Although both patients had rickets of prematurity, tubular dysfunction persisted after its resolution. Patient 2, who had severe chronic lung disease, also had elevated serum creatinine, proteinuria, and hypertension, suggesting glomerular damage. In patient 1, low molecular weight proteinuria, enzymuria, panaminoaciduria, hypercalciuria, and renal calcification were still present at the age of 8 years. In patient 2, tubular dysfunction resolved except for β2 microglobulinuria at the age of 5 years. While a reduced nephron number resulting in focal segmental glomerulosclerosis is well-known, generalized proximal tubular dysfunction can also occur in infants born preterm and/or with extremely low birth weight. PMID:28203565

  20. Cellularized microcarriers as adhesive building blocks for fabrication of tubular tissue constructs

    PubMed Central

    Twal, Waleed O.; Klatt, Sandra C.; Harikrishnan, Keerthi; Gerges, Ebtesam; Cooley, Marion A.; Trusk, Thomas C.; Zhou, Boran; Gabr, Mohamed G.; Shazly, Tarek; Lessner, Susan M.; Markwald, Roger R.; Argraves, W. Scott

    2013-01-01

    To meet demands of vascular reconstruction, there is a need for prosthetic alternatives to natural blood vessels. Here we explored a new conduit fabrication approach. Macroporous, gelatin microcarriers laden with human umbilical vein endothelial cells and aortic smooth muscle cells were dispensed into tubular agarose molds and found to adhere to form living tubular tissues. The ability of cellularized microcarriers to adhere to one another involved cellular and extracellular matrix bridging that included the formation of epithelium-like cell layers lining the lumenal and ablumenal surfaces of the constructs and the deposition of collagen and elastin fibers. The tubular tissues behaved as elastic solids, with a uniaxial mechanical response that is qualitatively similar to that of native vascular tissues and consistent with their elastin and collagen composition. Linearized measures of the mechanical response of the fabricated tubular tissues at both low and high strains was observed to increase with duration of static culture, with no significant loss of stiffness following decellularization. The findings highlight the utility of cellularized macroporous gelatin microcarriers as self-adhering building blocks for the fabrication of living tubular structures. PMID:23943070

  1. p-Cresol mediates autophagic cell death in renal proximal tubular cells.

    PubMed

    Lin, Hsin-Hung; Huang, Chiu-Ching; Lin, Tze-Yi; Lin, Ching-Yuang

    2015-04-02

    Higher serum level of p-cresol (PC) in chronic kidney disease (CKD) patients has been linked with CKD progression. The toxic effect of PC on diverse cells has been reported by prior studies, except for renal tubular cells. Both autophagy and apoptosis contribute to renal tubular cell death, yet evidence of its response to PC is limited and their crosstalk is still unclear. Autophagy is an important cellular process involved in toxin-induced cell death. Renal tubular cell death in tubular injury is thought to be one of the key events causing the progression of CKD. Thus, we treated rat (NRK-52E) and human (HRPTEC) renal proximal tubular cells (RPTC) with PC and found the cell proliferation was significantly decreased. Cell apoptosis was significantly increased and accompanied with the activation of autophagy as evidenced by increases in LC3-II, beclin 1 and Atg 4. We also found an increase of p62 by c-Jun activation. p62 accumulation could mediate the activation of caspase 8-dependent cell apoptosis. Conversely, knockdown of p62 by siRNA of p62 had the opposite effect by arresting LC3-II accumulation and promoting increasing cell viability. We conclude that PC triggered autophagic RPTC death via JNK-mediated p62 accumulation and then activated caspase 8-dependent cell death pathway. PC can be considered as one of the key events causing progression of CKD, which might affect drug disposition in CKD cases.

  2. Tubular Dickkopf-3 promotes the development of renal atrophy and fibrosis.

    PubMed

    Federico, Giuseppina; Meister, Michael; Mathow, Daniel; Heine, Gunnar H; Moldenhauer, Gerhard; Popovic, Zoran V; Nordström, Viola; Kopp-Schneider, Annette; Hielscher, Thomas; Nelson, Peter J; Schaefer, Franz; Porubsky, Stefan; Fliser, Danilo; Arnold, Bernd; Gröne, Hermann-Josef

    2016-01-21

    Renal tubular atrophy and interstitial fibrosis are common hallmarks of etiologically different progressive chronic kidney diseases (CKD) that eventually result in organ failure. Even though these pathological manifestations constitute a major public health problem, diagnostic tests, as well as therapeutic options, are currently limited. Members of the dickkopf (DKK) family, DKK1 and -2, have been associated with inhibition of Wnt signaling and organ fibrosis. Here, we identify DKK3 as a stress-induced, tubular epithelia-derived, secreted glycoprotein that mediates kidney fibrosis. Genetic as well as antibody-mediated abrogation of DKK3 led to reduced tubular atrophy and decreased interstitial matrix accumulation in two mouse models of renal fibrosis. This was facilitated by an amplified, antifibrogenic, inflammatory T cell response and diminished canonical Wnt/β-catenin signaling in stressed tubular epithelial cells. Moreover, in humans, urinary DKK3 levels specifically correlated with the extent of tubular atrophy and interstitial fibrosis in different glomerular and tubulointerstitial diseases. In summary, our data suggest that DKK3 constitutes an immunosuppressive and a profibrotic epithelial protein that might serve as a potential therapeutic target and diagnostic marker in renal fibrosis.

  3. Tubular Tissues and Organs of Human Body--Challenges in Regenerative Medicine.

    PubMed

    Góra, Aleksander; Pliszka, Damian; Mukherjee, Shayanti; Ramakrishna, Seeram

    2016-01-01

    Tissue engineering of tubular organs such as the blood vessel, trachea gastrointestinal tract, urinary tract are of the great interest due to the high amount of surgeries performed annually on those organs. Development in tissue engineering in recent years and promising results, showed need to investigate more complex constructs that need to be designed in special manner. Stent technology remain the most widely used procedure to restore functions of tubular tissues after cancer treatment, or after organ removal due to traumatic accidents. Tubular structures like blood vessels, intestines, and trachea have to work in specific environment at the boundary of the liquids, solids or air and surrounding tissues and ensure suitable separation between them. This brings additional challenges in tissue engineering science in order to construct complete organs by using combinations of various cells along with the support material systems. Here we give a comprehensive review of the tubular structures of the human body, in perspective of the current methods of treatment and progress in regenerative medicine that aims to develop fully functioning organs of tubular shape. Extensive analysis of the available literature has been done focusing on materials and methods of creations of such organs. This work describes the attempts to incorporate growth factors and drugs within the scaffolds to ensure localized drug release and enhance vascularization of the organ by attracting blood vessels to the site of implantation.

  4. Membrane magic

    SciTech Connect

    Buecker, B.

    2005-09-01

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

  5. Optimization of poly(L-lactic acid)/segmented polyurethane electrospinning process for the production of bilayered small-diameter nanofibrous tubular structures.

    PubMed

    Montini Ballarin, F; Caracciolo, P C; Blotta, E; Ballarin, V L; Abraham, G A

    2014-09-01

    The present study is focused on the electrospinning process as a versatile technique to obtain nanofibrous tubular structures for potential applications in vascular tissue engineering. A bilayered scaffolding structure composed of poly(L-lactic acid) (PLLA)/bioresorbable segmented polyurethane (SPEU) blends for small-diameter (5mm) vascular bypass grafts was obtained by multilayering electrospinning. Polymer blend ratios were chosen to mimic the media and adventitia layers. The influence of the different electrospinning parameters into the fiber formation, fiber morphology and fiber mean diameter for PLLA, SPEU and two PLLA/SPEU blends were studied. Flat and two-parallel plate collectors were used to analyze the effect of the electrostatic field on the PLLA nanofiber alignment in the rotating mandrel. Membrane topography resulted in random or aligned nanofibrous structures depending on the auxiliary collector setup used. Finally, composition, surface hydrophilicity, thermal properties and morphology of nanofibrous scaffolds were characterized and discussed. Since the development of tissue engineered microvascular prostheses is still a challenge, the prepared scaffolding tubular structures are promising candidates for vascular tissue engineering.

  6. Mitochondrial dysfunction contributes to the cytotoxicity induced by tentacle extract from the jellyfish Cyanea capillata in rat renal tubular epithelial NRK-52E cells.

    PubMed

    Wang, Tao; He, Qian; Xiao, Liang; Wang, Qianqian; Zhang, Bo; Wang, Beilei; Liu, Guoyan; Zheng, Jiemin; Yu, Bentong; Zhang, Liming

    2013-11-01

    Our previous studies have shown that tentacle extract (TE) from the jellyfish Cyanea capillata could induce a delayed jellyfish envenomation syndrome with severe multiple organ dysfunctions, among which renal injury with tubular necrosis seemed to be most serious. So, in this study, we aimed to explore the toxic effect of TE on rat renal tubular epithelial NRK-52E cells. Based on the previous findings that TE could cause oxidative damage in erythrocytes, the effects of TE on cell oxidative stress conditions, including ROS production and lipid peroxidation, and mitochondrial dysfunction associated with cell death were investigated in NRK-52E cells. The results showed that TE caused cell morphological change and decreased cell viability through induction of apoptosis and necrosis in NRK-52E cells. Meanwhile, ROS overproduction and mitochondrial membrane potential decrease were found before the cell death occurred. It was concluded that TE could induce cytotoxicity, especially apoptosis and necrosis, in NRK-52E cells, and mitochondrial dysfunction and ROS overproduction might play important roles in the process of cell injury and death.

  7. Oxygen Transport Membranes

    SciTech Connect

    S. Bandopadhyay

    2008-08-30

    small polaron conduction mechanism. Scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) were used to develop strategies to detect and characterize vacancy creation, dopant segregations and defect association in the oxygen conducting membrane material. The pO{sub 2} and temperature dependence of the conductivity, non-stoichiometry and thermal-expansion behavior of compositions with increasing complexity of substitution on the perovskite A and B sites were studied. Studies with the perovskite structure show anomalous behavior at low oxygen partial pressures (<10{sup -5} atm). The anomalies are due to non-equilibrium effects and can be avoided by using very strict criteria for the attainment of equilibrium. The slowness of the oxygen equilibration kinetics arises from two different mechanisms. In the first, a two phase region occurs between an oxygen vacancy ordered phase such as brownmillerite SrFeO{sub 2.5} and perovskite SrFeO{sub 3-x}. The slow kinetics is associated with crossing the two phase region. The width of the miscibility gap decreases with increasing temperature and consequently the effect is less pronounced at higher temperature. The preferred kinetic pathway to reduction of perovskite ferrites when the vacancy concentration corresponds to the formation of significant concentrations of Fe{sup 2+} is via the formation of a Ruddlesden-Popper (RP) phases as clearly observed in the case of La{sub 0.5}Sr{sub 0.5}FeO{sub 3-x} where LaSrFeO{sub 4} is found together with Fe. In more complex compositions, such as LSFTO, iron or iron rich phases are observed locally with no evidence for the presence of discrete RP phase. Fracture strength of tubular perovskite membranes was determined in air and in reducing atmospheric conditions. The strength of the membrane decreased with temperature and severity of reducing conditions although the strength distribution (Weibull parameter, m) was relatively unaltered. Surface and volume

  8. Dynamics of membrane nanotubes coated with I-BAR

    PubMed Central

    Barooji, Younes F.; Rørvig-Lund, Andreas; Semsey, Szabolcs; Reihani, S. Nader S.; Bendix, Poul M.

    2016-01-01

    Membrane deformation is a necessary step in a number of cellular processes such as filopodia and invadopodia formation and has been shown to involve membrane shaping proteins containing membrane binding domains from the IRSp53-MIM protein family. In reconstituted membranes the membrane shaping domains can efficiently deform negatively charged membranes into tubules without any other proteins present. Here, we show that the IM domain (also called I-BAR domain) from the protein ABBA, forms semi-flexible nanotubes protruding into Giant Unilamellar lipid Vesicles (GUVs). By simultaneous quantification of tube intensity and tubular shape we find both the diameter and stiffness of the nanotubes. I-BAR decorated tubes were quantified to have a diameter of ~50 nm and exhibit no stiffening relative to protein free tubes of the same diameter. At high protein density the tubes are immobile whereas at lower density the tubes diffuse freely on the surface of the GUV. Bleaching experiments of the fluorescently tagged I-BAR confirmed that the mobility of the tubes correlates with the mobility of the I-BAR on the GUV membrane. Finally, at low density of I-BAR the protein upconcentrates within tubes protruding into the GUVs. This implies that I-BAR exhibits strong preference for negatively curved membranes. PMID:27444356

  9. Dynamics of membrane nanotubes coated with I-BAR

    NASA Astrophysics Data System (ADS)

    Barooji, Younes F.; Rørvig-Lund, Andreas; Semsey, Szabolcs; Reihani, S. Nader S.; Bendix, Poul M.

    2016-07-01

    Membrane deformation is a necessary step in a number of cellular processes such as filopodia and invadopodia formation and has been shown to involve membrane shaping proteins containing membrane binding domains from the IRSp53-MIM protein family. In reconstituted membranes the membrane shaping domains can efficiently deform negatively charged membranes into tubules without any other proteins present. Here, we show that the IM domain (also called I-BAR domain) from the protein ABBA, forms semi-flexible nanotubes protruding into Giant Unilamellar lipid Vesicles (GUVs). By simultaneous quantification of tube intensity and tubular shape we find both the diameter and stiffness of the nanotubes. I-BAR decorated tubes were quantified to have a diameter of ~50 nm and exhibit no stiffening relative to protein free tubes of the same diameter. At high protein density the tubes are immobile whereas at lower density the tubes diffuse freely on the surface of the GUV. Bleaching experiments of the fluorescently tagged I-BAR confirmed that the mobility of the tubes correlates with the mobility of the I-BAR on the GUV membrane. Finally, at low density of I-BAR the protein upconcentrates within tubes protruding into the GUVs. This implies that I-BAR exhibits strong preference for negatively curved membranes.

  10. Potassium selectivity of frog gastric luminal membrane.

    PubMed

    Kasbekar, D K

    1986-06-01

    Transmural potential difference (PD) and resistance (R) changes after luminal or serosal instillation of K+ were determined under various conditions in chambered preparations of frog gastric mucosae. Potassium selectivity of the luminal membrane is indicated by the rapid reversal of the inverted PD of mucosae bathed in NaCl-free, choline sulfate (Ch2SO4)-Ringer on the serosal side and unbuffered hypertonic Ch2SO4 solution on the luminal side on luminal K+ instillation. The delta PD responses are significantly attenuated, however, in histamine-stimulated mucosae bathed in hypotonic or in burimamide-inhibited mucosae bathed in hyper- and hypotonic luminal media, which suggests that the K+ selectivity of the luminal membrane resides largely in the tubular cell apical membrane. Imposing a serosal-to-luminal transmucosal K+ gradient in both histamine-stimulated and omeprazole-inhibited mucosae also reversed the normal orientation of PD but not in those inhibited with burimamide. In the latter, the PD inversion was attenuated but maintained its normal orientation. These data suggest that burimamide, but not omeprazole, acts by blocking luminal membrane K+ conductance. The inverted PD in mucosae bathed in Cl-free media may thus be due partially or fully to K+ diffusion driven by the cell-to-lumen K+ gradient via the luminal K+ conductance pathway. These findings have implications for the controversy surrounding the postulated electrogenicity of the gastric proton pump.

  11. Vibration analysis of the tympanic membrane with a ventilation tube and a perforation by holography

    NASA Astrophysics Data System (ADS)

    Maeta, Manabu; Kawakami, Shinichiro; Ogawara, Toshiaki; Masuda, Yu

    1991-08-01

    For severe otitis media with effusion, insertion of a ventilation tube is performed for the purpose of ventilation of the middle ear cavity and normalization of the eustachian tubular function and middle ear mucosa. The ventilation tube is left in place for as long as several months or even a few years. However, the influence of the indwelling tube on vibration of the tympanic membrane is unknown. Therefore, the authors observed the influence by means of time-averaged holography using human tympanic membranes. The following results were obtained. After insertion of a ventilation tube, vibration pattern of the tympanic membrane was not obviously changed, but the vibration amplitude of the tympanic membrane was decreased, especially at 500 Hz. Generally speaking, the change caused by insertion of a ventilation tube was very small. Also, the vibration pattern of perforated tympanic membrane was not changed, but the vibration amplitude of perforated tympanic membrane was decreased at the low frequency area.

  12. Constitutive modeling of an electrospun tubular scaffold used for vascular tissue engineering.

    PubMed

    Hu, Jin-Jia

    2015-08-01

    In this study, we sought to model the mechanical behavior of an electrospun tubular scaffold previously reported for vascular tissue engineering with hyperelastic constitutive equations. Specifically, the scaffolds were made by wrapping electrospun polycaprolactone membranes that contain aligned fibers around a mandrel in such a way that they have microstructure similar to the native arterial media. The biaxial stress-stretch data of the scaffolds made of moderately or highly aligned fibers with three different off-axis fiber angles α (30°, 45°, and 60°) were fit by a phenomenological Fung model and a series of structurally motivated models considering fiber directions and fiber angle distributions. In particular, two forms of fiber strain energy in the structurally motivated model for a linear and a nonlinear fiber stress-strain relation, respectively, were tested. An isotropic neo-Hookean strain energy function was also added to the structurally motivated models to examine its contribution. The two forms of fiber strain energy did not result in significantly different goodness of fit for most groups of the scaffolds. The absence of the neo-Hookean term in the structurally motivated model led to obvious nonlinear stress-stretch fits at a greater axial stretch, especially when fitting data from the scaffolds with a small α. Of the models considered, the Fung model had the overall best fitting results; its applications are limited because of its phenomenological nature. Although a structurally motivated model using the nonlinear fiber stress-strain relation with the neo-Hookean term provided fits comparably as good as the Fung model, the values of its model parameters exhibited large within-group variations. Prescribing the dispersion of fiber orientation in the structurally motivated model, however, reduced the variations without compromising the fits and was thus considered to be the best structurally motivated model for the scaffolds. It appeared that the

  13. Calcitriol Directly Sensitizes Renal Tubular Cells to ATP-Depletion- and Iron-Mediated Attack

    PubMed Central

    Zager, Richard A.

    1999-01-01

    Vitamin Ds have been reported to have diverse effects on cell homeostasis, leading to suggestions that they have therapeutic applications extending beyond their traditional actions on the Ca2+/parathyroid/bone axis. As some of these potential indications carry an inherent risk of acute renal failure (ARF; eg, cancer chemotherapy and organ transplantation), the goal of this study was to assess whether vitamin Ds directly affect renal tubule injury responses. Cultured human proximal tubular (HK-2) cells were exposed to physiological or pharmacological doses of either calcitriol (D3) or a synthetic vitamin D2 analogue (19-nor) for 3 to 48 hours. Their impact on cell integrity (percent lactate dehydrogenase (LDH) release and tetrazolium dye MTT uptake) under basal conditions and during superimposed injuries (ATP depletion/Ca2+ ionophore or iron-mediated oxidant stress) were determined. As vitamin Ds can be anti-proliferative, cell outgrowth ([3H]thymidine uptake and crystal violet staining) was also tested. Finally, the action of D3 on in vivo ARF (glycerol-induced myoglobinuria) and isolated proximal tubule injury responses were assessed. D3 induced a rapid, dose-dependent increase in HK-2 susceptibility to both ATP-depletion/Ca2+-ionophore- and Fe-mediated attack without independently affecting cell integrity or proliferative responses. In contrast, D2 negatively affected only Fe toxicity and only after relatively prolonged exposure (48 hours). D3 dramatically potentiated in vivo ARF (two- to threefold increase in azotemia), suggesting potential in vivo relevance of the above HK-2 cell results. Proximal tubules, isolated from these glycerol-exposed mice, suggested that D3 can worsen tubule injury despite a parodoxic suppression of H2O2 production. In contrast, D3 had a mild negative impact on cellular energetics (depressed ATP/ADP ratios), and it accentuated plasma membrane phospholipid breakdown. The latter was observed in both glycerol-treated and control tubules

  14. Status report on the development of a tubular electron beam ion source

    NASA Astrophysics Data System (ADS)

    Donets, E. D.; Donets, E. E.; Becker, R.; Liljeby, L.; Rensfelt, K.-G.; Beebe, E. N.; Pikin, A. I.

    2004-05-01

    The theoretical estimations and numerical simulations of tubular electron beams in both beam and reflex mode of source operation as well as the off-axis ion extraction from a tubular electron beam ion source (TEBIS) are presented. Numerical simulations have been done with the use of the IGUN and OPERA-3D codes. Numerical simulations with IGUN code show that the effective electron current can reach more than 100 A with a beam current density of about 300-400 A/cm2 and the electron energy in the region of several KeV with a corresponding increase of the ion output. Off-axis ion extraction from the TEBIS, being the nonaxially symmetric problem, was simulated with OPERA-3D (SCALA) code. The conceptual design and main parameters of new tubular sources which are under consideration at JINR, MSL, and BNL are based on these simulations.

  15. Determination of short-circuit current in small tubular structures via cable analysis.

    PubMed

    Haag, K; Knauf, H

    1990-01-01

    Use of cable analysis is a time-consuming maneuver. On the other hand, the advantage of the cable method consists in obtaining the Isc and Rm related to unit area without the explicit measurement of inside radius r of the tubular structure. Obviously, application of the clamping technique requires, in addition, the determination of the surface area. In summary, for small tubular structures, such as the salivary ducts of rats and rabbits, and for human experiments, cable analysis is the method of choice for the Isc determination in vivo as well as in vitro. For larger tubular structures such as the rat colon the Isc should be determined in vivo by the clamping technique described above, whereas the in vitro measurements should be done in an Ussing-type chamber. In the intermediate range of size both in vivo techniques should be applied, in which case one method may serve as a check of the other.

  16. Micro-drilling of polymer tubular ultramicroelectrode arrays for electrochemical sensors.

    PubMed

    Kafka, Jan; Skaarup, Steen; Geschke, Oliver; Larsen, Niels B

    2013-05-14

    We present a reproducible fast prototyping procedure based on micro-drilling to produce homogeneous tubular ultramicroelectrode arrays made from poly(3,4-ethylenedioxythiophene) (PEDOT), a conductive polymer. Arrays of Ø 100 µm tubular electrodes each having a height of 0.37 ± 0.06 µm were reproducibly fabricated. The electrode dimensions were analyzed by SEM after deposition of silver dendrites to visualize the electroactive electrode area. The electrochemical applicability of the electrodes was demonstrated by voltammetric and amperometric detection of ferri-/ferrocyanide. Recorded signals were in agreement with results from finite element modelling of the system. The tubular PEDOT ultramicroelectrode arrays were modified by prussian blue to enable the detection of hydrogen peroxide. A linear sensor response was demonstrated for hydrogen peroxide concentrations from 0.1 mM to 1 mM.

  17. Population analysis of the cingulum bundle using the tubular surface model for schizophrenia detection

    NASA Astrophysics Data System (ADS)

    Mohan, Vandana; Sundaramoorthi, Ganesh; Kubicki, Marek; Terry, Douglas; Tannenbaum, Allen

    2010-03-01

    We propose a novel framework for population analysis of DW-MRI data using the Tubular Surface Model. We focus on the Cingulum Bundle (CB) - a major tract for the Limbic System and the main connection of the Cingulate Gyrus, which has been associated with several aspects of Schizophrenia symptomatology. The Tubular Surface Model represents a tubular surface as a center-line with an associated radius function. It provides a natural way to sample statistics along the length of the fiber bundle and reduces the registration of fiber bundle surfaces to that of 4D curves. We apply our framework to a population of 20 subjects (10 normal, 10 schizophrenic) and obtain excellent results with neural network based classification (90% sensitivity, 95% specificity) as well as unsupervised clustering (k-means). Further, we apply statistical analysis to the feature data and characterize the discrimination ability of local regions of the CB, as a step towards localizing CB regions most relevant to Schizophrenia.

  18. Development of Na-beta alumina batteries at Pacific Northwest National Laboratory: From tubular to planar

    SciTech Connect

    Lu, Xiaochuan; Li, Guosheng; Meinhardt, Kerry D.; Sprenkle, Vincent L.

    2016-07-28

    Na-beta alumina batteries are one of the most promising technologies for renewable energy storage and grid applications. Na-beta alumina batteries can be constructed in either tubular or planar designs, depending on the shape of the beta-alumina solid electrolyte. The tubular designs have been widely studied and developed since the 1960s primarily because of their ease of sealing. However, planar designs are considered superior to tubular designs in terms of power output, cell packing, ease of assembly, thermal management, and other characteristics. In this paper, we provide an overview on the basic battery electrochemistry, solid electrolyte synthesis and fabrication, battery designs, and future trends for further technology improvement.

  19. Extinction and near-extinction instability of non-premixed tubular flames

    SciTech Connect

    Hu, Shengteng; Pitz, Robert W.; Yu, Wang

    2009-01-15

    Tubular non-premixed flames are formed by an opposed tubular burner, a new tool to study the effects of curvature on extinction and flame instability of non-premixed flames. Extinction of the opposed tubular flames generated by burning diluted H{sub 2}, CH{sub 4} or C{sub 3}H{sub 8} with air is investigated for both concave and convex curvature. To examine the effects of curvature on extinction, the critical fuel dilution ratios at extinction are measured at various stretch rates, initial mixture strengths and flame curvature for fuels diluted in N{sub 2}, He, Ar or CO{sub 2}. In addition, the onset conditions of the cellular instability are mapped as a function of stretch rates, initial mixture strengths, and flame curvature. For fuel mixtures with Lewis numbers much less than unity, such as H{sub 2}/N{sub 2}, concave flame curvature towards the fuel suppresses cellular instabilities. (author)

  20. Endoplasmic reticulum stress and its effects on renal tubular cells apoptosis in ischemic acute kidney injury.

    PubMed

    Xu, Yan; Guo, Min; Jiang, Wei; Dong, Hui; Han, Yafei; An, Xiao-Fei; Zhang, Jisheng

    2016-06-01

    Ischemia is the most frequent cause of acute kidney injury (AKI), which is characterized by apoptosis of renal tubular cell. A common result of ischemia in AKI is dysfunction of endoplasmic reticulum (ER), which causes the protein-folding capacity to lag behind the protein-folding load. The abundance of misfolded proteins stressed the ER and results in induction of the unfolded protein response (UPR). While the UPR is an adaptive response, over time it can result in apoptosis when cells are unable to recover quickly. Recent research suggests that ER stress is a major factor in renal tubular cell apoptosis resulting from ischemic AKI. Thus, ER stress may be an important new progression factor in the pathology of ischemic AKI. In this article, we review UPR signaling, describe pathology and pathophysiology mechanisms of ischemic AKI, and highlight the dual function of ER stress on renal tubular cell apoptosis.

  1. Thermal sprayed composite melt containment tubular component and method of making same

    DOEpatents

    Besser, Matthew F.; Terpstra, Robert L.; Sordelet, Daniel J.; Anderson, Iver E.

    2002-03-19

    A tubular thermal sprayed melt containment component for transient containment of molten metal or alloy wherein the tubular member includes a thermal sprayed inner melt-contacting layer for contacting molten metal or alloy to be processed, a thermal sprayed heat-generating layer deposited on the inner layer, and an optional thermal sprayed outer thermal insulating layer. The thermal sprayed heat-generating layer is inductively heated as a susceptor of an induction field or electrical resistively heated by passing electrical current therethrough. The tubular thermal sprayed melt containment component can comprise an elongated melt pour tube of a gas atomization apparatus where the melt pour tube supplies molten material from a crucible to an underlying melt atomization nozzle.

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

    NASA Astrophysics Data System (ADS)

    Webster, Elizabeth T.

    Sol-gel methods for fabricating ceramic membranes on porous supports include dip coating, evaporative drying, and sintering. The ceramic membranes of interest in the present research were prepared from aqueous sols of silica, titania, or iron oxide nano-particles which were deposited on porous alumina supports. Physisorption measurements indicate that the diameters of the pores in the resulting membranes are 20 A or smaller. Defect formation during fabrication is particularly problematic for ceramic membranes with pore diameters in the nanometer range. Solutions to these problems would greatly enhance the commercial potential of nano-filtration membranes for gas-phase separations. Cracks are debilitating defects which originate during the drying and firing phases of fabrication. As water evaporates during drying, the sol-gel film is subjected to large capillary forces. Unchecked, these tensile forces result in catastrophic cracking across the membrane. A novel technique called internal deposition can be employed to deposit the sol particles within the pores of the support rather than on its surface. Internal deposition obstructs the propagation of cracks, thereby reducing the impact of crack-type defects. A patent for demonstration of proof of concept of the internal deposition technique has been received. Experimental difficulties associated with the nonuniform morphology of the tubular alumina support hindered further development of the internal deposition protocol. The final phase of the research incorporated a support containing uniform capillaries (Anotec(TM) disks). Two-level factorial experiments were conducted to determine the effects of various deposition and drying conditions (viz., speed and method of deposition, surface charge, humidity, and drying rate) on membrane performance. Membrane performance was characterized in terms of the permeabilities of nitrogen and helium in the resulting membranes. The permeability and pressure data were incorporated in

  3. IRSp53 senses negative membrane curvature and phase separates along membrane tubules

    PubMed Central

    Prévost, Coline; Zhao, Hongxia; Manzi, John; Lemichez, Emmanuel; Lappalainen, Pekka; Callan-Jones, Andrew; Bassereau, Patricia

    2015-01-01

    BAR domain proteins contribute to membrane deformation in diverse cellular processes. The inverted-BAR (I-BAR) protein IRSp53, for instance, is found on the inner leaflet of the tubular membrane of filopodia; however its role in the formation of these structures is incompletely understood. Here we develop an original assay in which proteins are encapsulated in giant unilamellar vesicles connected to membrane nanotubes. Our results demonstrate that I-BAR dimers sense negative membrane curvature. Experiment and theory reveal that the I-BAR displays a non-monotonic sorting with curvature, and expands the tube at high imposed tension while constricting it at low tension. Strikingly, at low protein density and tension, protein-rich domains appear along the tube. This peculiar behaviour is due to the shallow intrinsic curvature of I-BAR dimers. It allows constriction of weakly curved membranes coupled to local protein enrichment at biologically relevant conditions. This might explain how IRSp53 contributes in vivo to the initiation of filopodia. PMID:26469246

  4. Renal tubular receptor imaging with iodine-131-labeled peanut lectin: pharmacokinetics and renal clearance mechanism in animals

    SciTech Connect

    Boniface, G.R.; Suresh, M.R.; Willans, D.J.; Tam, Y.K.; Shysh, A.; Longenecker, B.M.; Noujaim, A.A.

    1986-05-01

    Intravenously administered peanut lectin (PNA), iodinated with /sup 131/I ((/sup 131/I)PNA), is rapidly cleared from the plasma by the kidneys in dogs (clearance (total body) = 17.52 +/- 8.74 ml/min). Dynamic gamma camera renal scintigraphy demonstrated renal accumulation and excretion phases of the (/sup 131/I)PNA renogram in dogs and rabbits (% injection dose-at-peak = 21.8 +/- 3.3% and 19.6 +/- 4.3%, time-to-peak = 44.6 +/- 4.8 min and 37.2 +/- 6.9 min, respectively). Immunoperoxidase staining of kidney sections, following i.v. administered PNA, demonstrated predominant accumulation by the proximal tubules of mice, rabbits, and dogs. The basement membrane was intensely stained at early times p.i. while intracellular and luminal PNA was evident within 1 hr. Urine analysis confirmed the presence of intact (/sup 131/I)PNA in the bladder contents, while protein degradation products, and a small percentage of the free iodide (less than 5%) were noted within 1 hr p.i. The relative proportion of free iodide increased at later times p.i. (greater than 6 hr). A receptor mediated excretion mechanism is proposed for the clearance of PNA and may be useful for the study of renal tubular function.

  5. Ceria catalyst for inert-substrate-supported tubular solid oxide fuel cells running on methane fuel

    NASA Astrophysics Data System (ADS)

    Zhao, Kai; Kim, Bok-Hee; Du, Yanhai; Xu, Qing; Ahn, Byung-Guk

    2016-05-01

    A ceria catalyst is applied to an inert-substrate supported tubular single cell for direct operation on methane fuel. The tubular single cell comprises a porous yttria-stabilized zirconia (YSZ) supporter, a Ni-Ce0.8Sm0.2O1.9 anode, a YSZ/Ce0.8Sm0.2O1.9 bi-layer electrolyte, and a La0.6Sr0.4Co0.2Fe0.8O3-δ cathode. The ceria catalyst is incorporated into the porous YSZ supporter layer by a cerium nitrate impregnation. The effects of ceria on the microstructure and electrochemical performance of the tubular single cell are investigated with respect to the number of impregnations. The optimum number of impregnations is determined to be four based on the maximum power density and polarization property of the tubular single cell in hydrogen and methane fuels. At 700 °C, the tubular single cell shows similar maximum power densities of ˜260 mW cm-2 in hydrogen and methane fuels, respectively. Moreover, the ceria catalyst significantly improves the performance stability of the cell running on methane fuel. At a current density of 350 mA cm-2, the single cell shows a low degradation rate of 2.5 mV h-1 during the 13 h test in methane fuel. These results suggest the feasibility of applying the ceria catalyst to the inert-substrate supported tubular single cell for direct operation on methane fuel.

  6. Penile urethra replacement with autologous cell-seeded tubularized collagen matrices.

    PubMed

    De Filippo, Roger E; Kornitzer, Benjamin S; Yoo, James J; Atala, Anthony

    2015-03-01

    Acellular collagen matrices have been used as an onlay material for urethral reconstruction. However, cell-seeded matrices have been recommended for tubularized urethral repairs. In this study we investigated whether long segmental penile urethral replacement using autologous cell-seeded tubularized collagen-based matrix is feasible. Autologous bladder epithelial and smooth muscle cells from nine male rabbits were grown and seeded onto preconfigured tubular matrices constructed from decellularized bladder matrices obtained from lamina propria. The entire anterior penile urethra was resected in 15 rabbits. Urethroplasties were performed with tubularized matrices seeded with cells in nine animals, and with matrices without cells in six. Serial urethrograms were performed at 1, 3 and 6 months. Retrieved urethral tissues were analysed using histo- and immunohistochemistry, western blot analyses and organ bath studies. The urethrograms showed that animals implanted with cell-seeded matrices maintained a wide urethral calibre without strictures. In contrast, the urethras with unseeded scaffolds collapsed and developed strictures. Histologically, a transitional cell layer surrounded by muscle was observed in the cell-seeded constructs. The epithelial and smooth muscle phenotypes were confirmed with AE1/AE3 and α-actin antibodies. Organ bath studies of the neourethras confirmed both physiological contractility and the presence of neurotransmitters. Tubularized collagen matrices seeded with autologous cells can be used successfully for long segmental penile urethra replacement, while implantation of tubularized collagen matrices without cells leads to poor tissue development and stricture formation. The cell-seeded collagen matrices are able to form new tissue, which is histologically similar to native urethra.

  7. In-Situ TEM-STM Observations of SWCNT Ropes/Tubular Transformations

    NASA Technical Reports Server (NTRS)

    Sola, F.; Lebron-Colon, M.; Ferreira, P. J.; Fonseca, L. F.; Meador, M. A.; Marin, C.

    2010-01-01

    Single-walled carbon nanotubes (SWCNTs) prepared by the HiPco process were purified using a modified gas phase purification technique. A TEM-STM holder was used to study the morphological changes of SWCNT ropes as a function of applied voltage. Kink formation, buckling behavior, tubular transformation and eventual breakdown of the system were observed. The tubular formation was attributed to a transformation from SWCNT ropes to multi-walled carbon nanotube (MWCNT) structures. It is likely mediated by the patching and tearing mechanism which is promoted primarily by the mobile vacancies generated due to current-induced heating and, to some extent, by electron irradiation.

  8. Nonimaging secondary concentrators for large rim angle parabolic troughs with tubular absorbers

    NASA Astrophysics Data System (ADS)

    Ries, Harald; Spirkl, Wolfgang

    1996-05-01

    For parabolic trough solar collectors with tubular absorbers, we design new tailored secondary concentrators. The design is applicable for any rim angle of a parabolic reflector. With the secondary, the concentration can be increased by a factor of more than 2 with a compact secondary reflector consisting of a single piece, even for the important case of a rim angle of 90 deg. The parabolic reflector can be used without changes; the reduced absorber is still tubular but smaller than the original absorber and slightly displaced toward the primary. concentrators, solar trough collectors, tailored reflectors.

  9. Stressed waveguides with tubular depressed-cladding inscribed in phosphate glasses by femtosecond hollow laser beams.

    PubMed

    Long, Xuewen; Bai, Jing; Zhao, Wei; Stoian, Razvan; Hui, Rongqing; Cheng, Guanghua

    2012-08-01

    We report on the single-step fabrication of stressed optical waveguides with tubular depressed-refractive-index cladding in phosphate glasses by the use of focused femtosecond hollow laser beams. Tubelike low index regions appear under direct exposure due to material rarefaction following expansion. Strained compacted zones emerged in domains neighboring the tubular track of lower refractive index, and waveguiding occurs mainly within the tube core fabricated by the engineered femtosecond laser beam. The refractive index profile of the optical waveguide was reconstructed from the measured transmitted near-field intensity.

  10. Femtosecond laser fabrication of tubular waveguides in poly(methyl methacrylate).

    PubMed

    Zoubir, Arnaud; Lopez, Cedric; Richardson, Martin; Richardson, Kathleen

    2004-08-15

    Femtosecond laser direct writing is employed for the fabrication of buried tubular waveguides in bulk poly(methyl methacrylate). A novel technique using selective chemical etching is presented to resolve the two-dimensional refractive-index profile of the fabrication structures. End-to-end coupling in the waveguides reveals a near-field intensity distribution that results from the superimposition of several propagating modes with different azimuthal symmetries. Mode analysis of the tubular waveguides is performed using the finite-difference method, and the possible propagating mode profiles are compared with the experimental data.

  11. Mesenchymal stem cells modulate albumin-induced renal tubular inflammation and fibrosis.

    PubMed

    Wu, Hao Jia; Yiu, Wai Han; Li, Rui Xi; Wong, Dickson W L; Leung, Joseph C K; Chan, Loretta Y Y; Zhang, Yuelin; Lian, Qizhou; Lin, Miao; Tse, Hung Fat; Lai, Kar Neng; Tang, Sydney C W

    2014-01-01

    Bone marrow-derived mesenchymal stem cells (BM-MSCs) have recently shown promise as a therapeutic tool in various types of chronic kidney disease (CKD) models. However, the mechanism of action is incompletely understood. As renal prognosis in CKD is largely determined by the degree of renal tubular injury that correlates with residual proteinuria, we hypothesized that BM-MSCs may exert modulatory effects on renal tubular inflammation and epithelial-to-mesenchymal transition (EMT) under a protein-overloaded milieu. Using a co-culture model of human proximal tubular epithelial cells (PTECs) and BM-MSCs, we showed that concomitant stimulation of BM-MSCs by albumin excess was a prerequisite for them to attenuate albumin-induced IL-6, IL-8, TNF-α, CCL-2, CCL-5 overexpression in PTECs, which was partly mediated via deactivation of tubular NF-κB signaling. In addition, albumin induced tubular EMT, as shown by E-cadherin loss and α-SMA, FN and collagen IV overexpression, was also prevented by BM-MSC co-culture. Albumin-overloaded BM-MSCs per se retained their tri-lineage differentiation capacity and overexpressed hepatocyte growth factor (HGF) and TNFα-stimulating gene (TSG)-6 via P38 and NF-κB signaling. Albumin-induced tubular CCL-2, CCL-5 and TNF-α overexpression were suppressed by recombinant HGF treatment, while the upregulation of α-SMA, FN and collagen IV was attenuated by recombinant TSG-6. Neutralizing HGF and TSG-6 abolished the anti-inflammatory and anti-EMT effects of BM-MSC co-culture in albumin-induced PTECs, respectively. In vivo, albumin-overloaded mice treated with mouse BM-MSCs had markedly reduced BUN, tubular CCL-2 and CCL-5 expression, α-SMA and collagen IV accumulation independent of changes in proteinuria. These data suggest anti-inflammatory and anti-fibrotic roles of BM-MSCs on renal tubular cells under a protein overloaded condition, probably mediated via the paracrine action of HGF and TSG-6.

  12. Dynamics of catalytic tubular microjet engines: Dependence on geometry and chemical environment

    NASA Astrophysics Data System (ADS)

    LiJ. X. L.; G. S. H. Contributed Equally To This Work., Jinxing; Huang, Gaoshan; Ye, Mengmeng; Li, Menglin; Liu, Ran; Mei, Yongfeng

    2011-12-01

    Strain-engineered tubular microjet engines with various geometric dimensions hold interesting autonomous motions in an aqueous fuel solution when propelled by catalytic decomposition of hydrogen peroxide to oxygen and water. The catalytically-generated oxygen bubbles expelled from microtubular cavities propel the microjet step by step in discrete increments. We focus on the dynamics of our tubular microjets in one step and build up a body deformation model to elucidate the interaction between tubular microjets and the bubbles they produce. The average microjet velocity is calculated analytically based on our model and the obtained results demonstrate that the velocity of the microjet increases linearly with the concentration of hydrogen peroxide. The geometric dimensions of the microjet, such as length and radius, also influence its dynamic characteristics significantly. A close consistency between experimental and calculated results is achieved despite a small deviation due to the existence of an approximation in the model. The results presented in this work improve our understanding regarding catalytic motions of tubular microjets and demonstrate the controllability of the microjet which may have potential applications in drug delivery and biology.Strain-engineered tubular microjet engines with various geometric dimensions hold interesting autonomous motions in an aqueous fuel solution when propelled by catalytic decomposition of hydrogen peroxide to oxygen and water. The catalytically-generated oxygen bubbles expelled from microtubular cavities propel the microjet step by step in discrete increments. We focus on the dynamics of our tubular microjets in one step and build up a body deformation model to elucidate the interaction between tubular microjets and the bubbles they produce. The average microjet velocity is calculated analytically based on our model and the obtained results demonstrate that the velocity of the microjet increases linearly with the

  13. Multiaxial fatigue behavior of tubular joints under variable amplitude loading conditions

    SciTech Connect

    Abel, A.; Wu, S.; Yu, X.

    1994-12-31

    An analytical approach has been developed for the study of fatigue life of tubular joints used in offshore structures when random loading conditions are applied. The method is based on linear elastic fracture mechanics and surface fatigue crack propagation. Using the line-spring element method, stress intensity factors of a part-through surface crack are computed. Crack propagation under random loading conditions with distribution parameters is calculated leading to fatigue life prediction if the statistical characteristics of random loading conditions are known. This method can be also used in predicting the remaining lives of tubular joints when cracks are detected and random loading conditions are applied.

  14. Tubular antigen-derivatized cells induce a disease-protective, antigen- specific, and idiotype-specific suppressor T cell network restricted by I-J and Igh-V in mice with experimental interstitial nephritis

    PubMed Central

    1985-01-01

    The nephritogenic effector T cell response producing interstitial nephritis in mice can be largely inhibited by the adoptive transfer of suppressor T cells before or after the induction of disease. These suppressor T cells are harvested from donor mice primed with tubular antigen-derivatized syngeneic lymphocytes, and two subsets of suppressor cells can be characterized within this donor cell population. The first suppressor cell in this network is an L3T4+, I- J+, RE-Id+ cell (Ts-1). Ts-1 cells are antigen-binding suppressor cells that inhibit afferent phase immune responses and, in the presence of tubular antigen, specifically induce Lyt-2+, I-J+ cells (Ts-2) that are antiidiotypic (RE-Id-binding) suppressors. The Ts-2 cell is functionally restricted in its suppressive effect by I-J and Igh-V gene products, and acts on the effector limb of the cell-mediated anti- tubular basement membrane immune response. These studies provide an experimental basis for further efforts to use immunoregulatory modulation in the control of autoimmune renal disease. PMID:3159824

  15. Alpha detection in pipes using an inverting membrane scintillator

    SciTech Connect

    Kendrick, D.T.; Cremer, C.D.; Lowry, W.

    1995-10-01

    Characterization of surface alpha emitting contamination inside enclosed spaces such as piping systems presents an interesting radiological measurement challenge. Detection of these alpha particles from the exterior of the pipe is impossible since the alpha particles are completely absorbed by the pipe wall. Traditional survey techniques, using hand-held instruments, simply can not be used effectively inside pipes. Science and Engineering Associates, Inc. is currently developing an enhancement to its Pipe Explorer{trademark} system that will address this challenge. The Pipe Explorer{trademark} uses a unique sensor deployment method where an inverted tubular membrane is propagated through complex pipe runs via air pressure. The inversion process causes the membrane to fold out against the pipe wall, such that no part of the membrane drags along the pipe wall. This deployment methodology has been successfully demonstrated at several DOE sites to transport specially designed beta and gamma, scintillation detectors into pipes ranging in length up to 250 ft.

  16. Characterization of Organic Anion Transporter 2 (SLC22A7): A Highly Efficient Transporter for Creatinine and Species-Dependent Renal Tubular Expression.

    PubMed

    Shen, Hong; Liu, Tongtong; Morse, Bridget L; Zhao, Yue; Zhang, Yueping; Qiu, Xi; Chen, Cliff; Lewin, Anne C; Wang, Xi-Tao; Liu, Guowen; Christopher, Lisa J; Marathe, Punit; Lai, Yurong

    2015-07-01

    The contribution of organic anion transporter OAT2 (SLC22A7) to the renal tubular secretion of creatinine and its exact localization in the kidney are reportedly controversial. In the present investigation, the transport of creatinine was assessed in human embryonic kidney (HEK) cells that stably expressed human OAT2 (OAT2-HEK) and isolated human renal proximal tubule cells (HRPTCs). The tubular localization of OAT2 in human, monkey, and rat kidney was characterized. The overexpression of OAT2 significantly enhanced the uptake of creatinine in OAT2-HEK cells. Under physiologic conditions (creatinine concentrations of 41.2 and 123.5 µM), the initial rate of OAT2-mediated creatinine transport was approximately 11-, 80-, and 80-fold higher than OCT2, multidrug and toxin extrusion protein (MATE)1, and MATE2K, respectively, resulting in approximately 37-, 1850-, and 80-fold increase of the intrinsic transport clearance when normalized to the transporter protein concentrations. Creatinine intracellular uptake and transcellular transport in HRPTCs were decreased in the presence of 50 µM bromosulfophthalein and 100 µM indomethacin, which inhibited OAT2 more potently than other known creatinine transporters, OCT2 and multidrug and toxin extrusion proteins MATE1 and MATE2K (IC50: 1.3 µM vs. > 100 µM and 2.1 µM vs. > 200 µM for bromosulfophthalein and indomethacin, respectively) Immunohistochemistry analysis showed that OAT2 protein was localized to both basolateral and apical membranes of human and cynomolgus monkey renal proximal tubules, but appeared only on the apical membrane of rat proximal tubules. Collectively, the findings revealed the important role of OAT2 in renal secretion and possible reabsorption of creatinine and suggested a molecular basis for potential species difference in the transporter handling of creatinine.

  17. Dicumarol, an inhibitor of ADP-ribosylation of CtBP3/BARS, fragments golgi non-compact tubular zones and inhibits intra-golgi transport.

    PubMed

    Mironov, Alexander A; Colanzi, Antonino; Polishchuk, Roman S; Beznoussenko, Galina V; Mironov, Alexander A; Fusella, Aurora; Di Tullio, Giuseppe; Silletta, Maria Giuseppina; Corda, Daniela; De Matteis, Maria Antonietta; Luini, Alberto

    2004-07-01

    Dicumarol (3,3'-methylenebis[4-hydroxycoumarin]) is an inhibitor of brefeldin-A-dependent ADP-ribosylation that antagonises brefeldin-A-dependent Golgi tubulation and redistribution to the endoplasmic reticulum. We have investigated whether dicumarol can directly affect the morphology of the Golgi apparatus. Here we show that dicumarol induces the breakdown of the tubular reticular networks that interconnect adjacent Golgi stacks and that contain either soluble or membrane-associated cargo proteins. This results in the formation of 65-120-nm vesicles that are sometimes invaginated. In contrast, smaller vesicles (45-65 nm in diameter, a size consistent with that of coat-protein-I-dependent vesicles) that excluded cargo proteins from their lumen are not affected by dicumarol. All other endomembranes are largely unaffected by dicumarol, including Golgi stacks, the ER, multivesicular bodies and the trans-Golgi network. In permeabilized cells, dicumarol activity depends on the function of CtBP3/BARS protein and pre-ADP-ribosylation of cytosol inhibits the breakdown of Golgi tubules by dicumarol. In functional experiments, dicumarol markedly slows down intra-Golgi traffic of VSV-G transport from the endoplasmic reticulum to the medial Golgi, and inhibits the diffusional mobility of both galactosyl transferase and VSV-G tagged with green fluorescent protein. However, it does not affect: transport from the trans-Golgi network to the cell surface; Golgi-to-endoplasmic reticulum traffic of ERGIC58; coat-protein-I-dependent Golgi vesiculation by AlF4 or ADP-ribosylation factor; or ADP-ribosylation factor and beta-coat protein binding to Golgi membranes. Thus the ADP-ribosylation inhibitor dicumarol induces the selective breakdown of the tubular components of the Golgi complex and inhibition of intra-Golgi transport. This suggests that lateral diffusion between adjacent stacks has a role in protein transport through the Golgi complex.

  18. 78 FR 9368 - Certain Oil Country Tubular Goods From the People's Republic of China: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-08

    ... International Trade Administration Certain Oil Country Tubular Goods From the People's Republic of China... tubular goods (``OCTG'') from the People's Republic of China (``PRC''). The period of review (``POR'') is...'s Republic of China: Amended Final Affirmative Countervailing Duty Determination and...

  19. Quasi-stationary Regime of Tubular Electron Beam Confinement in a Self-consistent Penning-Malmberg trap

    SciTech Connect

    Lapshin, V. I.; Tarasov, I. K.; Tkachenko, I. V.; Tkachenko, V. I.

    2006-01-15

    Results of investigations of collective trap formation for a tubular electron beam which propagates in the conducting cylinder with a longitudinal magnetic field are submitted. It is shown that collective trap forms due to the double potential sag occurrence. Long lived particles accumulation may be theoretically described in the terms of shearless electron tubular beam rotation.

  20. Cellular interactions via conditioned media induce in vivo nephron generation from tubular epithelial cells or mesenchymal stem cells

    SciTech Connect

    Machiguchi, Toshihiko Nakamura, Tatsuo

    2013-06-07

    Highlights: •We have attempted in vivo nephron generation using conditioned media. •Vascular and tubular cells do cross-talks on cell proliferation and tubular changes. •Tubular cells suppress these changes in mesenchymal stem cells. •Tubular cells differentiate mesenchymal stem cells into tubular cells. •Nephrons can be created from implanted tubular cells or mesenchymal stem cells. -- Abstract: There are some successful reports of kidney generation by utilizing the natural course of kidney development, namely, the use of an artificially treated metanephros, blastocyst or ureteric bud. Under a novel concept of cellular interactions via conditioned media (CMs), we have attempted in vivo nephron generation from tubular epithelial cells (TECs) or mesenchymal stem cells (MSCs). Here we used 10× CMs of vascular endothelial cells (VECs) and TECs, which is the first to introduce a CM into the field of organ regeneration. We first present stimulative cross-talks induced by these CMs between VECs and TECs on cell proliferation and morphological changes. In MSCs, TEC-CM suppressed these changes, however, induced cytokeratin expression, indicating the differentiation of MSCs into TECs. As a result, glomerular and tubular structures were created following the implantation of TECs or MSCs with both CMs. Our findings suggest that the cellular interactions via CMs might induce in vivo nephron generation from TECs or MSCs. As a promoting factor, CMs could also be applied to the regeneration of other organs and tissues.

  1. Comparative analysis of the outdoor culture of Haematococcus pluvialis in tubular and bubble column photobioreactors.

    PubMed

    López, M C García-Malea; Sánchez, E Del Río; López, J L Casas; Fernández, F G Acién; Sevilla, J M Fernández; Rivas, J; Guerrero, M G; Grima, E Molina

    2006-05-29

    The present paper makes a comparative analysis of the outdoor culture of H. pluvialis in a tubular photobioreactor and a bubble column. Both reactors had the same volume and were operated in the same way, thus allowing the influence of the reactor design to be analyzed. Due to the large changes in cell morphology and biochemical composition of H. pluvialis during outdoor culture, a new, faster methodology has been developed for their evaluation. Characterisation of the cultures is carried out on a macroscopic scale using a colorimetric method that allows the simultaneous determination of biomass concentration, and the chlorophyll, carotenoid and astaxanthin content of the biomass. On the microscopic scale, a method was developed based on the computer analysis of digital microscopic images. This method allows the quantification of cell population, average cell size and population homogeneity. The accuracy of the methods was verified during the operation of outdoor photobioreactors on a pilot plant scale. Data from the reactors showed tubular reactors to be more suitable for the production of H. pluvialis biomass and/or astaxanthin, due to their higher light availability. In the tubular photobioreactor biomass concentrations of 7.0 g/L (d.wt.) were reached after 16 days, with an overall biomass productivity of 0.41 g/L day. In the bubble column photobioreactor, on the other hand, the maximum biomass concentration reached was 1.4 g/L, with an overall biomass productivity of 0.06 g/L day. The maximum daily biomass productivity, 0.55 g/L day, was reached in the tubular photobioreactor for an average irradiance inside the culture of 130 microE/m2s. In addition, the carotenoid content of biomass from tubular photobioreactor increased up to 2.0%d.wt., whereas that of the biomass from the bubble column remained roughly constant at values of 0.5%d.wt. It should be noted that in the tubular photobioreactor under conditions of nitrate saturation, there was an accumulation of

  2. Potentialities of a Membrane Reactor with Laccase Grafted Membranes for the Enzymatic Degradation of Phenolic Compounds in Water

    PubMed Central

    Chea, Vorleak; Paolucci-Jeanjean, Delphine; Sanchez, José; Belleville, Marie-Pierre

    2014-01-01

    This paper describes the degradation of phenolic compounds by laccases from Trametes versicolor in an enzymatic membrane reactor (EMR). The enzymatic membranes were prepared by grafting laccase on a gelatine layer previously deposited onto α-alumina tubular membranes. The 2,6-dimethoxyphenol (DMP) was selected  from among the three different phenolic compounds tested (guaiacol, 4-chlorophenol and DMP) to study the performance of the EMR in dead end configuration. At the lowest feed substrate concentration tested (100 mg·L−1), consumption increased with flux (up to 7.9 × 103 mg·h−1·m−2 at 128 L·h−1·m−2), whereas at the highest substrate concentration (500 mg·L−1), it was shown that the reaction was limited by the oxygen content. PMID:25295628

  3. Potentialities of a membrane reactor with laccase grafted membranes for the enzymatic degradation of phenolic compounds in water.

    PubMed

    Chea, Vorleak; Paolucci-Jeanjean, Delphine; Sanchez, José; Belleville, Marie-Pierre

    2014-10-06

    This paper describes the degradation of phenolic compounds by laccases from Trametes versicolor in an enzymatic membrane reactor (EMR). The enzymatic membranes were prepared by grafting laccase on a gelatine layer previously deposited onto α-alumina tubular membranes. The 2,6-dimethoxyphenol (DMP) was selected  from among the three different phenolic compounds tested (guaiacol, 4-chlorophenol and DMP) to study the performance of the EMR in dead end configuration. At the lowest feed substrate concentration tested (100 mg·L-1), consumption increased with flux (up to 7.9 × 103 mg·h-1·m-2 at 128 L·h-1·m-2), whereas at the highest substrate concentration (500 mg·L-1), it was shown that the reaction was limited by the oxygen content.

  4. Horizontally rotated cell culture system with a coaxial tubular oxygenator

    NASA Technical Reports Server (NTRS)

    Wolf, David A. (Inventor); Schwarz, Ray P. (Inventor); Trinh, Tinh T. (Inventor)

    1991-01-01

    The present invention relates to a horizontally rotating bioreactor useful for carrying out cell and tissue culture. For processing of mammalian cells, the system is sterilized and fresh fluid medium, microcarrier beads, and cells are admitted to completely fill the cell culture vessel. An oxygen containing gas is admitted to the interior of the permeable membrane which prevents air bubbles from being introduced into the medium. The cylinder is rotated at a low speed within an incubator so that the circular motion of the fluid medium uniformly suspends the microbeads throughout the cylinder during the cell growth period. The unique design of this cell and tissue culture device was initially driven by two requirements imposed by its intended use for feasibility studies for three dimensional culture of living cells and tissues in space by JSC. They were compatible with microgravity and simulation of microgravity in one G. The vessels are designed to approximate the extremely quiescent low shear environment obtainable in space.

  5. G418-mediated ribosomal read-through of a nonsense mutation causing autosomal recessive proximal renal tubular acidosis

    PubMed Central

    Azimov, Rustam; Abuladze, Natalia; Sassani, Pakan; Newman, Debra; Kao, Liyo; Liu, Weixin; Orozco, Nicholas; Ruchala, Piotr; Pushkin, Alexander; Kurtz, Ira

    2008-01-01

    Autosomal recessive proximal renal tubular acidosis is caused by mutations in the SLC4A4 gene encoding the electrogenic sodium bicarbonate cotransporter NBCe1-A. The mutations that have been characterized thus far result in premature truncation, mistargeting, or decreased function of the cotransporter. Despite bicarbonate treatment to correct the metabolic acidosis, extrarenal manifestations persist, including glaucoma, cataracts, corneal opacification, and mental retardation. Currently, there are no known therapeutic approaches that can specifically target mutant NBCe1-A proteins. In the present study, we tested the hypothesis that the NBCe1-A-Q29X mutation can be rescued in vitro by treatment with aminoglycoside antibiotics, which are known for their ability to suppress premature stop codons. As a model system, we cloned the NBCe1-A-Q29X mutant into a vector lacking an aminoglycoside resistance gene and transfected the mutant cotransporter in HEK293-H cells. Cells transfected with the NBCe1-A-Q29X mutant failed to express the cotransporter because of the premature stop codon. Treatment of the cells with G418 significantly increased the expression of the full-length cotransporter, as assessed by immunoblot analysis. Furthermore, immunocytochemical studies demonstrated that G418 treatment induced cotransporter expression on the plasma membrane whereas in the absence of G418, NBCe1-A-Q29X was not expressed. In HEK293-H cells transfected with the NBCe1-A-Q29X mutant not treated with G418, NBCe1-A-mediated flux was not detectable. In contrast, in cells transfected with the NBCe1-A-Q29X mutant, G418 treatment induced Na+- and HCO3−-dependent transport that did not differ from wild-type NBCe1-A function. G418 treatment in mock-transfected cells was without effect. In conclusion, G418 induces ribosomal read-through of the NBCe1-A-Q29X mutation in HEK293-H cells. These findings represent the first evidence that in the presence of the NBCe1-A-Q29X mutation that causes

  6. G418-mediated ribosomal read-through of a nonsense mutation causing autosomal recessive proximal renal tubular acidosis.

    PubMed

    Azimov, Rustam; Abuladze, Natalia; Sassani, Pakan; Newman, Debra; Kao, Liyo; Liu, Weixin; Orozco, Nicholas; Ruchala, Piotr; Pushkin, Alexander; Kurtz, Ira

    2008-09-01

    Autosomal recessive proximal renal tubular acidosis is caused by mutations in the SLC4A4 gene encoding the electrogenic sodium bicarbonate cotransporter NBCe1-A. The mutations that have been characterized thus far result in premature truncation, mistargeting, or decreased function of the cotransporter. Despite bicarbonate treatment to correct the metabolic acidosis, extrarenal manifestations persist, including glaucoma, cataracts, corneal opacification, and mental retardation. Currently, there are no known therapeutic approaches that can specifically target mutant NBCe1-A proteins. In the present study, we tested the hypothesis that the NBCe1-A-Q29X mutation can be rescued in vitro by treatment with aminoglycoside antibiotics, which are known for their ability to suppress premature stop codons. As a model system, we cloned the NBCe1-A-Q29X mutant into a vector lacking an aminoglycoside resistance gene and transfected the mutant cotransporter in HEK293-H cells. Cells transfected with the NBCe1-A-Q29X mutant failed to express the cotransporter because of the premature stop codon. Treatment of the cells with G418 significantly increased the expression of the full-length cotransporter, as assessed by immunoblot analysis. Furthermore, immunocytochemical studies demonstrated that G418 treatment induced cotransporter expression on the plasma membrane whereas in the absence of G418, NBCe1-A-Q29X was not expressed. In HEK293-H cells transfected with the NBCe1-A-Q29X mutant not treated with G418, NBCe1-A-mediated flux was not detectable. In contrast, in cells transfected with the NBCe1-A-Q29X mutant, G418 treatment induced Na(+)- and HCO(3)(-)-dependent transport that did not differ from wild-type NBCe1-A function. G418 treatment in mock-transfected cells was without effect. In conclusion, G418 induces ribosomal read-through of the NBCe1-A-Q29X mutation in HEK293-H cells. These findings represent the first evidence that in the presence of the NBCe1-A-Q29X mutation that

  7. Dynamic sorting of lipids and proteins in membrane tubes with a moving phase boundary

    PubMed Central

    Heinrich, Michael; Tian, Aiwei; Esposito, Cinzia; Baumgart, Tobias

    2010-01-01

    Cellular organelle membranes maintain their integrity, global shape, and composition despite vigorous exchange among compartments of lipids and proteins during trafficking and signaling. Organelle homeostasis involves dynamic molecular sorting mechanisms that are far from being understood. In contrast, equilibrium thermodynamics of membrane mixing and sorting, particularly the phase behavior of binary and ternary model membrane mixtures and its coupling to membrane mechanics, is relatively well characterized. Elucidating the continuous turnover of live cell membranes, however, calls for experimental and theoretical membrane models enabling manipulation and investigation of directional mass transport. Here we introduce the phenomenon of curvature-induced domain nucleation and growth in membrane mixtures with fluid phase coexistence. Membrane domains were consistently observed to nucleate precisely at the junction between a strongly curved cylindrical (tube) membrane and a pipette-aspirated giant unilamellar vesicle. This experimental geometry mimics intracellular sorting compartments, because they often show tubular-vesicular membrane regions. Nucleated domains at tube necks were observed to present diffusion barriers to the transport of lipids and proteins. We find that curvature-nucleated domains grow with characteristic parabolic time dependence that is strongly curvature-dependent. We derive an analytical model that reflects the observed growth dynamics. Numerically calculated membrane shapes furthermore allow us to elucidate mechanical details underlying curvature-dependent directed lipid transport. Our observations suggest a novel dynamic membrane sorting principle that may contribute to intracellular protein and lipid sorting and trafficking. PMID:20368457

  8. Cis and trans interactions between atlastin molecules during membrane fusion

    PubMed Central

    Liu, Tina Y.; Bian, Xin; Romano, Fabian B.; Shemesh, Tom; Rapoport, Tom A.; Hu, Junjie

    2015-01-01

    Atlastin (ATL), a membrane-anchored GTPase that mediates homotypic fusion of endoplasmic reticulum (ER) membranes, is required for formation of the tubular network of the peripheral ER. How exactly ATL mediates membrane fusion is only poorly understood. Here we show that fusion is preceded by the transient tethering of ATL-containing vesicles caused by the dimerization of ATL molecules in opposing membranes. Tethering requires GTP hydrolysis, not just GTP binding, because the two ATL molecules are pulled together most strongly in the transition state of GTP hydrolysis. Most tethering events are futile, so that multiple rounds of GTP hydrolysis are required for successful fusion. Supported lipid bilayer experiments show that ATL molecules sitting on the same (cis) membrane can also undergo nucleotide-dependent dimerization. These results suggest that GTP hydrolysis is required to dissociate cis dimers, generating a pool of ATL monomers that can dimerize with molecules on a different (trans) membrane. In addition, tethering and fusion require the cooperation of multiple ATL molecules in each membrane. We propose a comprehensive model for ATL-mediated fusion that takes into account futile tethering and competition between cis and trans interactions. PMID:25825753

  9. Tubular kidney damage and centrilobular liver injury after intratracheal instillation of dimethyl selenide.

    PubMed

    Cherdwongcharoensuk, Duangrudee; Henrique, Rui; Upatham, Suchart; Pereira, António Sousa; Aguas, Artur P

    2005-01-01

    Accidental inhalation of selenium (Se) derivatives, such as dimethyl selenide (DMSe), has been associated with damage of respiratory tissues. However, systemic effects of inhaled Se have not been thoroughly established. We have investigated whether mouse kidney and liver show cellular pathology as a result of a single intratracheal instillation of two different doses of DMSe (0.05 and 0.1 mg Se/kg BW). The animals were sacrificed 1, 7, 14, and 28 days after either 1 of the 2 DMSe treatments; samples were studied by light microscopy. Instillation of the low DMSe dose resulted in acute and transient tubular disease of the kidney expressed by swelling and vacuolation of epithelial cells of proximal tubules; in some mice, tubular necrosis was observed. After 14 days of the DMSe treatment, these lesions were ameliorated and, by day 28, the kidney tubular epithelium depicted a normal morphology. The same low dose of DMSe caused sustained damage to centrilobular hepatocytes characterized by swollen and vacuolized liver cells. After the instillation of the high DMSe dose, the mice presented sustained liver and kidney focal necrosis. Our data suggest that inhalation of DMSe results in: (i) acute tubular injury of the kidney and damage to centrilobular liver cells and (ii) this systemic pathology induced by DMSe is a dose-dependent phenomenon.

  10. 46 CFR 154.1320 - Sighting ports, tubular gauge glasses, and flat plate type gauge glasses.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Sighting ports, tubular gauge glasses, and flat plate type gauge glasses. 154.1320 Section 154.1320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... glasses, and flat plate type gauge glasses. (a) Cargo tanks may have sighting ports as a secondary...

  11. 46 CFR 154.1320 - Sighting ports, tubular gauge glasses, and flat plate type gauge glasses.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Sighting ports, tubular gauge glasses, and flat plate type gauge glasses. 154.1320 Section 154.1320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... glasses, and flat plate type gauge glasses. (a) Cargo tanks may have sighting ports as a secondary...

  12. 46 CFR 154.1320 - Sighting ports, tubular gauge glasses, and flat plate type gauge glasses.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Sighting ports, tubular gauge glasses, and flat plate type gauge glasses. 154.1320 Section 154.1320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... glasses, and flat plate type gauge glasses. (a) Cargo tanks may have sighting ports as a secondary...

  13. 46 CFR 154.1320 - Sighting ports, tubular gauge glasses, and flat plate type gauge glasses.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Sighting ports, tubular gauge glasses, and flat plate type gauge glasses. 154.1320 Section 154.1320 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... glasses, and flat plate type gauge glasses. (a) Cargo tanks may have sighting ports as a secondary...

  14. High-temperature, high-pressure bonding of nested tubular metallic components

    DOEpatents

    Quinby, T.C.

    A tool is described for effecting high-temperature, high-compression bonding between the confronting faces of nested, tubular, metallic components. In a typical application, the tool is used to produce tubular target assemblies for irradiation in nuclear reactors or particle accelerators. The target assembly comprising a uranum foil and an aluninum-alloy substrate. The tool is composed of graphite. It comprises a tubular restraining member in which a mechanically expandable tubular core is mounted to form an annulus. The components to be bonded are mounted in nested relation in the annulus. The expandable core is formed of individually movable, axially elongated segments whose outer faces cooperatively define a cylindrical pressing surface and whose inner faces cooperatively define two opposed, inwardly tapered, axial bores. Tapered rams extend into the bores. The loaded tool is mounted in a conventional hot-press provided with evacuation means, heaters for maintaining its interior at bonding temperature, and hydraulic cylinders for maintaining a selected inwardly directed pressure on the tapered rams. With the hot-press evacuated and the loaded tool at the desired temperature, the cylinders are actuated to apply the selected pressure to the rams. The rams in turn expand the segmented core to maintain the nested components in compression against the restraining member. These conditions are maintained until the confronting faces of the nested components are joined in a continuous, uniform bond characterized by high thermal conductivity.

  15. High-temperature, high-pressure bonding of nested tubular metallic components

    DOEpatents

    Quinby, Thomas C.

    1980-01-01

    This invention is a tool for effecting high-temperature, high-compression bonding between the confronting faces of nested, tubular, metallic components. In a typical application, the tool is used to produce tubular target assemblies for irradiation in nuclear reactors or particle accelerators, the target assembly comprising a uranium foil and an aluminum-alloy substrate. The tool preferably is composed throughout of graphite. It comprises a tubular restraining member in which a mechanically expandable tubular core is mounted to form an annulus with the member. The components to be bonded are mounted in nested relation in the annulus. The expandable core is formed of individually movable, axially elongated segments whose outer faces cooperatively define a cylindrical pressing surface and whose inner faces cooperatively define two opposed, inwardly tapered, axial bores. Tapered rams extend respectively into the bores. The loaded tool is mounted in a conventional hot-press provided with evacuation means, heaters for maintaining its interior at bonding temperature, and hydraulic cylinders for maintaining a selected inwardly directed pressure on the tapered rams. With the hot-press evacuated and the loaded tool at the desired temperature, the cylinders are actuated to apply the selected pressure to the rams. The rams in turn expand the segmented core to maintain the nested components in compression against the restraining member. These conditions are maintained until the confronting faces of the nested components are joined in a continuous, uniform bond characterized by high thermal conductivity.

  16. Forced chemical vapor infiltration of tubular geometries: Modeling, design, and scale-up

    SciTech Connect

    Stinton, D.P.; Besmann, T.M.; Matlin, W.M.; Starr, T.L.; Curtain, W.A.

    1995-10-01

    The development of thick-walled, tubular ceramic composites has involved investigations of different fiber architectures and fixturing to obtain optimal densification and mechanical properties. The current efforts entail modeling of the densification process in order to increase densification uniformity and decrease processing time. In addition, the process is being scaled to produce components with a 10 cm outer diameter.

  17. Tubular cross talk in acute kidney injury: a story of sense and sensibility.

    PubMed

    El-Achkar, Tarek M; Dagher, Pierre C

    2015-06-15

    The mammalian kidney is an organ composed of numerous functional units or nephrons. Beyond the filtering glomerulus of each nephron, various tubular segments with distinct populations of epithelial cells sequentially span the kidney from cortex to medulla. The highly organized folding of the tubules results in a spatial distribution that allows intimate contact between various tubular subsegments. This unique arrangement can promote a newly recognized type of horizontal epithelial-to-epithelial cross talk. In this review, we discuss the importance of this tubular cross talk in shaping the response of the kidney to acute injury in a sense and sensibility model. We propose that injury-resistant tubules such as S1 proximal segments and thick ascending limbs (TAL) can act as "sensors" and thus modulate the responsiveness or "sensibility" of the S2-S3 proximal segments to injury. We also discuss new findings that highlight the importance of tubular cross talk in regulating homeostasis and inflammation not only in the kidney, but also systemically.

  18. Open Tubular Lab-On-Column/Mass Spectrometry for Targeted Proteomics of Nanogram Sample Amounts

    PubMed Central

    Hustoft, Hanne Kolsrud; Vehus, Tore; Brandtzaeg, Ole Kristian; Krauss, Stefan; Greibrokk, Tyge; Wilson, Steven Ray; Lundanes, Elsa

    2014-01-01

    A novel open tubular nanoproteomic platform featuring accelerated on-line protein digestion and high-resolution nano liquid chromatography mass spectrometry (LC-MS) has been developed. The platform features very narrow open tubular columns, and is hence particularly suited for limited sample amounts. For enzymatic digestion of proteins, samples are passed through a 20 µm inner diameter (ID) trypsin + endoproteinase Lys-C immobilized open tubular enzyme reactor (OTER). Resulting peptides are subsequently trapped on a monolithic pre-column and transferred on-line to a 10 µm ID porous layer open tubular (PLOT) liquid chromatography LC separation column. Wnt/ß-catenein signaling pathway (Wnt-pathway) proteins of potentially diagnostic value were digested+detected in targeted-MS/MS mode in small cell samples and tumor tissues within 120 minutes. For example, a potential biomarker Axin1 was identifiable in just 10 ng of sample (protein extract of ∼1,000 HCT15 colon cancer cells). In comprehensive mode, the current OTER-PLOT set-up could be used to identify approximately 1500 proteins in HCT15 cells using a relatively short digestion+detection cycle (240 minutes), outperforming previously reported on-line digestion/separation systems. The platform is fully automated utilizing common commercial instrumentation and parts, while the reactor and columns are simple to produce and have low carry-over. These initial results point to automated solutions for fast and very sensitive MS based proteomics, especially for samples of limited size. PMID:25222838

  19. A tubular-coring device for use in biogeochemical sampling of succulent and pulpy plants

    USGS Publications Warehouse

    Campbell, W.L.

    1986-01-01

    A hand-operated, tubular-coring device developed for use in biogeochemical sampling of succulent and pulpy plants is described. The sampler weighs about 500 g (1.1 lb); and if 25 ?? 175 mm (1 ?? 7 in) screw-top test tubes are used as sample containers, the complete sampling equipment kit is easily portable, having both moderate bulk and weight. ?? 1986.

  20. 78 FR 56865 - Certain Oil Country Tubular Goods From India and Turkey: Postponement of Preliminary...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-16

    ... International Trade Administration Certain Oil Country Tubular Goods From India and Turkey: Postponement of...) 482-3964 (India); Shane Subler at (202) 482-0189 (Turkey), AD/CVD Operations, Import Administration... and Turkey.\\1\\ Currently, the preliminary determinations are due no later than September 25, 2013....