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Sample records for 10kw tubular sofc

  1. Development of tubular SOFC using metallic substrate

    SciTech Connect

    Nagata, S.; Okuo, T.; Kaga, Y.; Kasuga, Y.; Momma, K.; Tsukamoto, K.; Uchiyama, F.

    1995-12-31

    The tubular SOFCs using porous metallic substrates have been developed. The substrates can act as excellent fuel electrodes of low activation polarizations by baking fine Ni layers on them. These substrates can be compatible with other materials composing SOFCs in life tests including sudden and scheduled interruptions. The cells were fabricated by the combined method of the spray process and the wet process. In the life test at 1,198K, the power density of 0.3W/cm{sup 2} was kept over 3,000 hours at the current density of 0.4A/cm{sup 2}.

  2. Reactions of hydrocarbons in small tubular SOFCs

    NASA Astrophysics Data System (ADS)

    Saunders, G. J.; Kendall, K.

    The benefits of SOFCs are likely to be optimally realised using fuels other than pure hydrogen, which is best employed in PEMFCs. This paper examines a number of plausible fuels including pure alkanes such as methane and iso-octane. Other compounds such as ammonia, methanol and methanoic acid have been shown to react very cleanly when injected directly into the SOFC. More complex fuels, e.g. ethanol and ethanoic acid tend to produce carbon deposits unless the inlet stream is much diluted, e.g. with argon or carbon dioxide. More complex real fuels such as natural gas, landfill gas and gasoline are also mentioned. The experiments involved mixing the fuel with a carrier gas and passing the composition down a zirconia fuel cell tube to examine electrochemical output, while analysing the reaction products using mass spectroscopy. Any carbon deposited was measured by temperature programmed oxidation at the end of the experiment. Windows of operation were found for many of the fuels examined.

  3. 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}.

  4. 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.

  5. Tubular SOFC and SOFC/Gas Turbine combined cycles-status and prospects

    SciTech Connect

    Veyo, S.E.; Lundberg, W.L.

    1996-12-31

    Presently under fabrication at Westinghouse for EDB/ELSAM, a consortium of Dutch and Danish utilities, is the world`s first 100 kWe Solid Oxide Fuel Cell (SOFC) power generation system. This natural gas fueled experimental field unit will be installed near Arnhem, The Netherlands, at an auxiliary district heating plant (Hulp Warmte Centrale) at the Rivierweg in Westervoort, a site provided by NUON, one of the Dutch participants, and will supply ac power to the utility grid and hot water to the district heating system serving the Duiven/Westervoort area. The electrical generation efficiency of this simple cycle atmospheric pressure system will approach 50%. The analysis of conceptual designs for larger capacity systems indicates that the horizon for the efficiency of simple cycle atmospheric pressure units is about 55%.

  6. Development of a Low Cost 10kW Tubular SOFC Power System

    SciTech Connect

    Bessette, Norman; Litka, Anthony; Rawson, Jolyon; Schmidt, Douglas

    2013-06-06

    The DOE program funded from 2003 through early 2013 has brought the Acumentrics SOFC program from an early stage R&D program to an entry level commercial product offering. The development work started as one of the main core teams under the DOE Solid State Energy Conversion Alliance (SECA) program administered by the National Energy Technology Laboratory (NETL) of the DOE. During the first phase of the program, lasting approximately 3-4 years, a 5kW machine was designed, manufactured and tested against the specification developed by NETL. This unit was also shipped to NETL for independent verification testing which validated all of the results achieved while in the laboratory at Acumentrics. The Acumentrics unit passed all criteria established from operational stability, efficiency, and cost projections. Passing of the SECA Phase I test allowed the program to move into Phase II of the program. During this phase, the overall objective was to further refine the unit meeting a higher level of performance stability as well as further cost reductions. During the first year of this new phase, the NETL SECA program was refocused towards larger size units and operation on coal gasification due to the severe rise in natural gas prices and refocus on the US supply of indigenous coal. At this point, the program was shifted to the U.S. DOE’s Energy Efficiency and Renewable Energy (EERE) division located in Golden, Colorado. With this shift, the focus remained on smaller power units operational on gaseous fuels for a variety of applications including micro combined heat and power (mCHP). To achieve this goal, further enhancements in power, life expectancy and reductions in cost were necessary. The past 5 years have achieved these goals with machines that can now achieve over 40% electrical efficiency and field units that have now operated for close to a year and a half with minimal maintenance. The following report details not only the first phase while under the SECA program

  7. Fundamental researches of SOFC in Russia

    SciTech Connect

    Demin, A.K.; Neuimin, A.D.; Perfiliev, M.V.

    1996-04-01

    The main results of research on ZrO{sub 2}-based solid electrolytes, electrodes and interconnects are reviewed. The mathematical models of the processes in SOFC are considered. Two types of SOFC stacks composed of tubular and block cells, as well the results of their tests are described.

  8. 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.

  9. Trade Study on Aggregation of Multiple 10-KW Solid Ozide Fuel Cell Power Modules

    SciTech Connect

    Ozpineci, B.

    2004-12-03

    According to the Solid State Energy Conversion Alliance (SECA) program guidelines, solid oxide fuel cells (SOFC) will be produced in the form of 3-10 kW modules for residential use. In addition to residential use, these modules can also be used in apartment buildings, hospitals, etc., where a higher power rating would be required. For example, a hospital might require a 250 kW power generating capacity. To provide this power using the SECA SOFC modules, 25 of the 10 kW modules would be required. These modules can be aggregated in different architectures to yield the necessary power. This report will show different approaches for aggregating numerous SOFC modules and will evaluate and compare each one with respect to cost, control complexity, ease of modularity, and fault tolerance.

  10. 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.

  11. SOFC INTERCONNECT DEVELOPMENT

    SciTech Connect

    Diane M. England

    2004-03-16

    An interconnect for an SOFC stack is used to connect fuel cells into a stack. SOFC stacks are expected to run for 40,000 hours and 10 thermal cycles for the stationary application and 10,000 hours and 7000 thermal cycles for the transportation application. The interconnect of a stack must be economical and robust enough to survive the SOFC stack operation temperature of 750 C and must maintain the electrical connection to the fuel cells throughout the lifetime and under thermal cycling conditions. Ferritic and austenitic stainless steels, and nickel-based superalloys were investigated as possible interconnect materials for solid oxide fuel cell (SOFC) stacks. The alloys were thermally cycled in air and in a wet nitrogen-argon-hydrogen (N2-Ar-H2-H2O) atmosphere. Thermogravimetry was used to determine the parabolic oxidation rate constants of the alloys in both atmospheres. The area-specific resistance of the oxide scale and metal substrates were measured using a two-probe technique with platinum contacts. The study identifies two new interconnect designs which can be used with both bonded and compressive stack sealing mechanisms. The new interconnect designs offer a solution to chromium vaporization, which can lead to degradation of some (chromium-sensitive) SOFC cathodes.

  12. Design studies of mobile applications with SOFC-heat engine modules

    NASA Astrophysics Data System (ADS)

    Winkler, Wolfgang; Lorenz, Hagen

    The recent development of thin tubular solid oxide fuel cells (SOFCs), microturbines and Stirling engines has inspired design studies of the integration of a SOFC-heat engine (HE) system within a car. The total power system consists of a SOFC-HE power generation unit, a power storage (battery) system, a power management system and electric motors at the wheels. The sizes of the HE and the SOFC stack are to be matched by the start-up requirements. The use of micro tubes allows a very high power density of the stack. The thermodynamic calculation of the cycle gives the actual design values for the study and indicates further steps for system optimisation. The first SOFC-GT layout lead to an electric efficiency of 45% for the cycle used as a base for a design study [The Design of Stationary and Mobile SOFC-GT Systems, UECT, 2001]. The design study shows that the space available in a mid-class car allows the integration of such a system including space reserves. A further improvement of the system might allow an electric efficiency of more than 55%. The integration of a Stirling engine instead of the microturbine is a second possibility and the object of an ongoing study. This was motivated by interesting results from the development of solar powered Stirling engines. Generally, the analyses show that the optimal match of the SOFC and the HE will be a key issue for any engineering solution.

  13. Micro-tubular solid oxide fuel cell based on a porous yttria-stabilized zirconia support

    PubMed Central

    Panthi, Dhruba; Tsutsumi, Atsushi

    2014-01-01

    Solid oxide fuel cells (SOFCs) are promising electrochemical energy conversion devices owing to their high power generation efficiency and environmentally benign operation. Micro-tubular SOFCs, which have diameters ranging from a few millimeters to the sub-millimeter scale, offer several advantages over competing SOFCs such as high volumetric power density, good endurance against thermal cycling, and flexible sealing between fuel and oxidant streams. Herein, we successfully realized a novel micro-tubular SOFC design based on a porous yttria-stabilized zirconia (YSZ) support using multi-step dip coating and co-sintering methods. The micro-tubular SOFC consisted of Ni-YSZ, YSZ, and strontium-doped lanthanum manganite (LSM)–YSZ as the anode, electrolyte, and cathode, respectively. In addition, to facilitate current collection from the anode and cathode, Ni and LSM were applied as an anode current collector and cathode current collector, respectively. Micro-crystalline cellulose was selected as a pore former to achieve better shrinkage behavior of the YSZ support so that the electrolyte layer could be densified at a co-sintering temperature of 1300°C. The developed micro-tubular design showed a promising electrochemical performance with maximum power densities of 525, 442, and 354 mW cm−2 at 850, 800, and 750°C, respectively. PMID:25169166

  14. Development of 10kW SOFC module

    SciTech Connect

    Hisatome, N.; Nagata, K.; Kakigami, S.

    1996-12-31

    Mitsubishi Heavy industries, Ltd. (MHI) has been developing tubular type Solid Oxide Fuel Cells (SOFC) since 1984. A 1 kW module of SOFC has been continuously operated for 3,000 hours with 2 scheduled thermal cycles at Electric Power Development Co., Inc. (EPDC) Wakamatsu Power Station in 1993. We have obtained of 34% (HHV as H{sub 2}) module efficiency and deterioration rate of 2% Per 1,000 hours in this field test. As for next step, we have developed 10 kW module in 1995. The 10 kW module has been operated for 5,000 hours continuously. This module does not need heating support to maintain the operation temperature, and the module efficiency was 34% (HHV as H{sub 2}). On the other hand, we have started developing the technology of pressurized SOFC. In 1996, pressurized MW module has been tested at MHI Nagasaki Shipyard & Machinery, Works. We are now planning the development of pressurized 10 kW module.

  15. Clean combined-cycle SOFC power plant — cell modelling and process analysis

    NASA Astrophysics Data System (ADS)

    Riensche, E.; Achenbach, E.; Froning, D.; Haines, M. R.; Heidug, W. K.; Lokurlu, A.; von Andrian, S.

    The design principle of a specially adapted solid-oxide fuel cell power plant for the production of electricity from hydrocarbons without the emission of greenhouse gases is described. To achieve CO 2 separation in the exhaust stream, it is necessary to burn the unused fuel without directly mixing it with air, which would introduce nitrogen. Therefore, the spent fuel is passed over a bank of oxygen ion conducting tubes very similar in configuration to the electrochemical tubes in the main stack of the fuel cell. In such an SOFC system, pure CO 2 is produced without the need for a special CO 2 separation process. After liquefaction, CO 2 can be re-injected into an underground reservoir. A plant simulation model consists of four main parts, that is, turbo-expansion of natural gas, fuel cell stack, periphery of the stack, and CO 2 recompression. A tubular SOFC concept is preferred. The spent fuel leaving the cell tube bundle is burned with pure oxygen instead of air. The oxygen is separated from the air in an additional small tube bundle of oxygen separation tubes. In this process, mixing of CO 2 and N 2 is avoided, so that liquefaction of CO 2 becomes feasible. As a design tool, a computer model for tubular cells with an air feed tube has been developed based on an existing planar model. Plant simulation indicates the main contributors to power production (tubular SOFC, exhaust air expander) and power consumption (air compressor, oxygen separation).

  16. Refractory Glass Seals for SOFC

    SciTech Connect

    Chou, Y. S.; Stevenson, Jeffry W.

    2011-07-01

    One of the critical challenges facing planar solid oxide fuel cell (SOFC) technology is the need for reliable sealing technology. Seals must exhibit long-term stability and mechanical integrity in the high temperature SOFC environment during normal and transient operation. Several different approaches for sealing SOFC stacks are under development, including glass or glass-ceramic seals, metallic brazes, and compressive seals. Among glass seals, rigid glass-ceramics, self-healing glass, and composite glass approaches have been investigated under the SECA Core Technology Program. The U.S. Department of Energy's Pacific Northwest National Laboratory (PNNL) has developed the refractory glass approach in light of the fact that higher sealing temperatures (e.g., 930-1000 degrees C) may enhance the ultimate in-service bulk strength and electrical conductivity of contact materials, as well as the bonding strength between contact materials and adjacent SOFC components, such as interconnect coatings and electrodes. This report summarizes the thermal, chemical, mechanical, and electrical properties of the refractory sealing glass.

  17. Anodic Concentration Polarization in SOFCs

    SciTech Connect

    Williford, Rick E.; Chick, Lawrence A.; Maupin, Gary D.; Simner, Steve P.; Stevenson, Jeffry W.; Khaleel, Mohammad A.; Wachsman, ED, et al

    2003-08-01

    Concentration polarization is important because it determines the maximum power output of a solid oxide fuel cell (SOFC) at high fuel utilization. Anodic concentration polarization occurs when the demand for reactants exceeds the capacity of the porous ceramic anode to supply them by gas diffusion mechanisms. High tortuosities (bulk diffusion resistances) are often assumed to explain this behavior. However, recent experiments show that anodic concentration polarization originates in the immediate vicinity of the reactive triple phase boundary (TPB) sites near the anode/electrolyte interface. A model is proposed to describe how concentration polarization is controlled by two localized phenomena: competitive adsorption of reactants in areas adjacent to the reactive TPB sites, followed by relatively slow surface diffusion to the reactive sites. Results suggest that future SOFC design improvements should focus on optimization of the reactive area, adsorption, and surface diffusion at the anode/electrolyte interface.

  18. HYDROCARBON AND SULFUR SENSORS FOR SOFC SYSTEMS

    SciTech Connect

    A.M. Azad; Chris Holt; Todd Lesousky; Scott Swartz

    2003-11-01

    The following report summarizes work conducted during the Phase I program Hydrocarbon and Sulfur Sensors for SOFC Systems under contract No. DE-FC26-02NT41576. For the SOFC application, sensors are required to monitor hydrocarbons and sulfur in order to increase the operation life of SOFC components. This report discusses the development of two such sensors, one based on thick film approach for sulfur monitoring and the second galvanic based for hydrocarbon monitoring.

  19. Influence of the anodic recirculation transient behaviour on the SOFC hybrid system performance

    NASA Astrophysics Data System (ADS)

    Ferrari, Mario L.; Traverso, Alberto; Magistri, Loredana; Massardo, Aristide F.

    This paper addresses the off-design and transient response of a high efficiency hybrid system based on the coupling of a recuperated micro-gas turbine (mGT) with a tubular solid oxide fuel cell (SOFC) reactor. The work focuses on the anodic side where an ejector exploits the pressure energy of the fuel to recirculate part of the exhaust gas, in order to maintain a proper value for the steam-to-carbon ratio (STCR) and to support the reforming reactions. Two different stand-alone time-dependent ejector models are presented and validated against experimental data. Then, the most suitable model for cycle simulations, in term of calculation time, has been employed for the transient analysis of the entire hybrid system. The SOFC hybrid system transient behaviour is presented and discussed at several operating conditions from an electrochemical, fluid dynamic and thermal point of view.

  20. A 1000-cell SOFC reactor for domestic cogeneration

    NASA Astrophysics Data System (ADS)

    Alston, T.; Kendall, K.; Palin, M.; Prica, M.; Windibank, P.

    A cogeneration system was built using 1000 cells with the intention of supplying 30 kW of hot water and 500 W of power. The basis of the cogenerator was the small tubular SOFC design. 8Y zirconia was mixed into a plastic paste and extruded to form thin-walled tubes. The process produced a zirconia material with high strength and good electrical properties. After drying and firing to full density, electrodes were coated onto the inner and outer surfaces of the electrolyte, then sintered. Current collecting wires were wound around the tubular cells and the tubes were assembled into a reactor. Either hydrogen or a premix of natural gas and air was fed through the tubes and ignited by a hot wire. The ignition shock did not damage the cells in any way. Cycling was achieved within minutes. A steel heat exchanger/recuperator was used to feed hot air to the cell stack. The electrical output was measured via a potentiostat.

  1. Review of the micro-tubular solid oxide fuel cell. Part I. Stack design issues and research activities

    NASA Astrophysics Data System (ADS)

    Lawlor, V.; Griesser, S.; Buchinger, G.; Olabi, A. G.; Cordiner, S.; Meissner, D.

    Fuel cells are devices that convert chemical energy in hydrogen enriched fuels into electricity electrochemically. Micro-tubular solid oxide fuel cells (MT-SOFCs), the type pioneered by K. Kendall in the early 1990s, are a variety of SOFCs that are on the scale of millimetres compared to their much larger SOFC relatives that are typically on the scale of tens of centimetres. The main advantage of the MT-SOFC, over its larger predecessor, is that it is smaller in size and is more suitable for rapid start up. This may allow the SOFC to be used in devices such as auxiliary power units, automotive power supplies, mobile electricity generators and battery re-chargers. The following paper is Part I of a two part series. Part I will introduce the reader to the MT-SOFC stack and its applications, indicating who is researching what in this field and also specifically investigate the design issues related to multi-cell reactor systems called stacks. Part II will review in detail the combinations of materials and methods used to produce the electrodes and electrolytes of MT-SOFC's. Also the role of modelling and validation techniques used in the design and improvement of the electrodes and electrolytes will be investigated. A broad range of scientific and engineering disciplines are involved in a stack design. Scientific and engineering content has been discussed in the areas of thermal-self-sustainability and efficiency, sealing technologies, manifold design, electrical connections and cell performance optimisation.

  2. Biogas powering a small tubular solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Staniforth, J.; Kendall, K.

    Biogas has been used to power a small tubular solid oxide fuel cell (SOFC). It was demonstrated that biogas could provide power equivalent to hydrogen, even when the methane content was reduced below the value at which normal combustion could occur. The carbon dioxide content of biogas was especially beneficial because it aided the internal reforming process. But carbon deposition was a problem unless air was added to the biogas before it entered the cell. When air was premixed, the biogas was comparable with than hydrogen in the power produced. However, a problem was the variability of biogas samples. Of the three types tested, only one produced a consistent power output.

  3. SOFC technology development at Rolls-Royce

    NASA Astrophysics Data System (ADS)

    Gardner, F. J.; Day, M. J.; Brandon, N. P.; Pashley, M. N.; Cassidy, M.

    Fuel cells have the prospect for exploiting fossil fuels more benignly and more efficiently than alternatives. The various types represent quite different technologies, with no clear winner, yet. Nevertheless, the high temperature MCFC and solid oxide fuel cell (SOFC) types seem better suited to power generation in a hydrocarbon fuel economy. Presently, the costs of MCFCs and SOFCs are too high to compete directly with contemporary power generation plant. Seeking to overcome the drawbacks of first generation fuel cells, over the past 7 years an innovative second generation SOFC concept has been evolved in the Rolls-Royce Strategic Research Centre, with encouraging results. It is distinguished from other types by the name: Integrated Planar Solid Oxide Fuel Cell (IP-SOFC). It is a family of integrated system concepts supporting product flexibility with evolutionary stretch potential from a common SOFC module. Fabrication of the key component of the IP-SOFC, the "multi-cell membrane electrode assembly (multi-cell MEA) module" carrying many series connected cells with supported electrolyte membranes only 10 to 20 μm thick, has been proved. Development of the internal reforming subsystem, the next big hurdle, is now in hand. Following an outline of its salient features and test results, the methodology and results of recent IP-SOFC stack costing studies are presented, and the continuing research and development programme indicated.

  4. Advanced tubular solid oxide fuel cells with high efficiency for internal reforming of hydrocarbon fuels

    NASA Astrophysics Data System (ADS)

    Cheekatamarla, Praveen K.; Finnerty, Caine M.; Du, Yanhai; Jiang, Juan; Dong, Jian; Dewald, P. G.; Robinson, C. R.

    Solid oxide fuel cells (SOFCs) constitute an attractive power-generation technology that converts chemical energy directly into electricity while causing little pollution. NanoDynamics Energy (NDE) Inc. has developed micro-tubular SOFC-based portable power generation systems that run on both gaseous and liquid fuels. In this paper, we present our next generation solid oxide fuel cells that exhibit total efficiencies in excess of 60% running on hydrogen fuel and 40+% running on readily available gaseous hydrocarbon fuels such as propane, butane etc. The advanced fuel cell design enables power generation at very high power densities and efficiencies (lower heating value-based) while reforming different hydrocarbon fuels directly inside the tubular SOFC without the aid of fuel pre-processing/reforming. The integrated catalytic layered SOFC demonstrated stable performance for >1000 h at high efficiency while running on propane fuel at sub-stoichiometric oxygen-to-fuel ratios. This technology will facilitate the introduction of highly efficient, reliable, fuel flexible, and lightweight portable power generation systems.

  5. The ways of SOFC systems efficiency increasing

    SciTech Connect

    Demin, A.K.; Timofeyeva, N.

    1996-04-01

    The efficiency of solid oxide fuel cells (SOFCs) is described. This paper considers methods to lift the fuel utilization and/or the average cell voltage with the goal of increasing the cell efficiency by improved cell designs.

  6. Development of Residential SOFC Cogeneration System

    NASA Astrophysics Data System (ADS)

    Ono, Takashi; Miyachi, Itaru; Suzuki, Minoru; Higaki, Katsuki

    2011-06-01

    Since 2001 Kyocera has been developing 1kW class Solid Oxide Fuel Cell (SOFC) for power generation system. We have developed a cell, stack, module and system. Since 2004, Kyocera and Osaka Gas Co., Ltd. have been developed SOFC residential co-generation system. From 2007, we took part in the "Demonstrative Research on Solid Oxide Fuel Cells" Project conducted by New Energy Foundation (NEF). Total 57 units of 0.7kW class SOFC cogeneration systems had been installed at residential houses. In spite of residential small power demand, the actual electric efficiency was about 40%(netAC,LHV), and high CO2 reduction performance was achieved by these systems. Hereafter, new joint development, Osaka Gas, Toyota Motors, Kyocera and Aisin Seiki, aims early commercialization of residential SOFC CHP system.

  7. A supramolecular tubular nanoreactor.

    PubMed

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

    2014-07-01

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

  8. Formulating liquid ethers for microtubular SOFCs

    NASA Astrophysics Data System (ADS)

    Kendall, Kevin; Slinn, Matthew; Preece, John

    One of the key problems of applying solid oxide fuel cells (SOFCs) in transportation is that conventional fuels like kerosene and diesel do not operate directly in SOFCs without prereforming to hydrogen and carbon monoxide which can be handled by the nickel cermet anode. SOFCs can internally reform certain hydrocarbon molecules such as methanol and methane. However, other liquid fuels usable in petrol or diesel internal combustion engines (ICEs) have not easily been reformable directly on the anode. This paper describes a search for liquid fuels which can be mixed with petrol or diesel and also injected directly into an SOFC without destroying the nickel anode. When fuel molecules such as octane are injected onto the conventional nickel/yttria stabilised zirconia (Ni/YSZ) SOFC fuel electrode, the anode rapidly becomes blocked by carbon deposition and the cell power drops to near zero in minutes. This degeneration of the anode can be inhibited by injection of air or water into the anode or by some upstream reforming just before entry to the SOFC. Some smaller molecules such as methane, methanol and methanoic acid produce a slight tendency to carbon deposition but not sufficient to prevent long term operation. In this project we have investigated a large number of molecules and now found that some liquid ethers do not significantly damage the anode when directly injected. These molecules and formulations with other components have been evaluated in this study. The theory put forward in this paper is that carbon-carbon bonds in the fuel are the main reason for anode damage. By testing a number of fuels without such bonds, particularly liquid ethers such as methyl formate and dimethoxy methane, it has been shown that SOFCs can run without substantial carbon formation. The proposal is that conventional fuels can be doped with these molecules to allow hybrid operation of an ICE/SOFC device.

  9. Performance and long term degradation of 7 W micro-tubular solid oxide fuel cells for portable applications

    NASA Astrophysics Data System (ADS)

    Torrell, M.; Morata, A.; Kayser, P.; Kendall, M.; Kendall, K.; Tarancón, A.

    2015-07-01

    Micro-tubular SOFCs have shown an astonishing thermal shock resistance, many orders of magnitude larger than planar SOFCs, opening the possibility of being used in portable applications. However, only few studies have been devoted to study the degradation of large-area micro-tubular SOFCs. This work presents microstructural, electrochemical and long term degradation studies of single micro-tubular cells fabricated by high shear extrusion, operating in the intermediate range of temperatures (T∼700 °C). A maximum power of 7 W per cell has been measured in a wide range of fuel utilizations between 10% and 60% at 700 °C. A degradation rate of 360 mW/1000 h (8%) has been observed for cells operated over more than 1500 h under fuel utilizations of 40%. Higher fuel utilizations lead to strong degradations associated to nickel oxidation/reduction processes. Quick thermal cycling with heating ramp rates of 30 °C /min yielded degradation rates of 440 mW/100 cycles (9%). These reasonable values of degradation under continuous and thermal cycling operation approach the requirements for many portable applications including auxiliary power units or consumer electronics opening this typically forbidden market to the SOFC technology.

  10. Metal supported tubular solid oxide fuel cells fabricated by suspension plasma spray and suspension high velocity oxy-fuel spray

    NASA Astrophysics Data System (ADS)

    Yoo, Yeong; Wang, Youliang; Deng, Xiaohua; Singh, Devinder; Legoux, Jean-Gabriel

    2012-10-01

    Low temperature (LT) metal supported solid oxide fuel cells (SOFCs) have many advantages in comparison to conventional electrode or electrolyte supported type SOFCs. NRC has demonstrated high performance LT metal supported planar SOFCs fabricated by either wet colloidal spray/sintering or suspension thermal spray. The combination of tubular configuration and metal supported SOFCs may produce more unique and very attractive advantages such as easy and inexpensive sealing method and materials, high specific and volumetric power density, cost-effective fabrication, enhanced robustness, rapid start up, red-ox cycle tolerance and potential use for a pressurized integrated system. In this paper, thin film solid electrolyte of Sm0.2Ce0.8O1.90 (SDC) and NiO-SDC composite anode on sintered porous tubular metal supports were deposited by suspension HVOF spray and suspension plasma spray, respectively on sintered porous tubular metal support. La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode on the SDC electrolyte was formed by wet colloidal spray and subsequent sintering process as the final fabrication step. The detailed investigation of suspension and process-related parameters for suspension thermal spray was performed in order to produce thin and crack-free SDC thin film coatings. The electrochemical performance of single cells was demonstrated.

  11. Fuel Cell Power Plant Initiative. Volume 2; Preliminary Design of a Fixed-Base LFP/SOFC Power System

    NASA Technical Reports Server (NTRS)

    Veyo, S.E.

    1997-01-01

    This report documents the preliminary design for a military fixed-base power system of 3 MWe nominal capacity using Westinghouse's tubular Solid Oxide Fuel Cell [SOFC] and Haldor Topsoe's logistic fuels processor [LFP]. The LFP provides to the fuel cell a methane rich sulfur free fuel stream derived from either DF-2 diesel fuel, or JP-8 turbine fuel. Fuel cells are electrochemical devices that directly convert the chemical energy contained in fuels such as hydrogen, natural gas, or coal gas into electricity at high efficiency with no intermediate heat engine or dynamo. The SOFC is distinguished from other fuel cell types by its solid state ceramic structure and its high operating temperature, nominally 1000'C. The SOFC pioneered by Westinghouse has a tubular geometry closed at one end. A power generation stack is formed by aggregating many cells in an ordered array. The Westinghouse stack design is distinguished from other fuel cell stacks by the complete absence of high integrity seals between cell elements, cells, and between stack and manifolds. Further, the reformer for natural gas [predominantly methane] and the stack are thermally and hydraulically integrated with no requirement for process water. The technical viability of combining the tubular SOFC and a logistic fuels processor was demonstrated at 27 kWe scale in a test program sponsored by the Advanced Research Projects Agency [ARPA) and carried out at the Southern California Edison's [SCE] Highgrove generating station near San Bernardino, California in 1994/95. The LFP was a breadboard design supplied by Haldor Topsoe, Inc. under subcontract to Westinghouse. The test program was completely successful. The LFP fueled the SOFC for 766 hours on JP-8 and 1555 hours of DF-2. In addition, the fuel cell operated for 3261 hours on pipeline natural gas. Over the 5582 hours of operation, the SOFC generated 118 MVVH of electricity with no perceptible degradation in performance. The LFP processed military

  12. Recent Development of SOFC Metallic Interconnect

    SciTech Connect

    Wu JW, Liu XB

    2010-04-01

    Interest in solid oxide fuel cells (SOFC) stems from their higher e±ciencies and lower levels of emitted pollu- tants, compared to traditional power production methods. Interconnects are a critical part in SOFC stacks, which connect cells in series electrically, and also separate air or oxygen at the cathode side from fuel at the anode side. Therefore, the requirements of interconnects are the most demanding, i:e:, to maintain high elec- trical conductivity, good stability in both reducing and oxidizing atmospheres, and close coe±cient of thermal expansion (CTE) match and good compatibility with other SOFC ceramic components. The paper reviewed the interconnect materials, and coatings for metallic interconnect materials.

  13. Development of Osaka gas type planar SOFC

    SciTech Connect

    Iha, M.; Shiratori, A.; Chikagawa, O.

    1996-12-31

    Osaka Gas Co. has been developing a planar type SOFC (OG type SOFC) which has a suitable structure for stacking. Murata Mfg. Co. has begun to develop the OG type SOFC stack through joint program since 1993. Figure 1 shows OG type cell structure. Because each cell is sustained by cell holders acting air manifold, the load of upper cell is not put on the lower cells. Single cell is composed of 3-layered membrane and LaCrO{sub 3} separator. 5 single cells are mounted on the cell holder, connected with Ni felt electrically, and bonded by glassy material sealant. We call the 5-cell stack a unit. Stacking 13 units, we succeeded 870 W generation in 1993. But the power density was low, 0.11 Wcm{sup -2} because of crack in the electrolyte and gas leakage at some cells.

  14. Solid State Energy Conversion Alliance Delphi SOFC

    SciTech Connect

    Steven Shaffer; Gary Blake; Sean Kelly; Subhasish Mukerjee; Karl Haltiner; Larry Chick; David Schumann; Jeff Weissman; Gail Geiger; Ralphi Dellarocco

    2006-12-31

    The following report details the results under the DOE SECA program for the period July 2006 through December 2006. Developments pertain to the development of a 3 to 5 kW Solid Oxide Fuel Cell power system for a range of fuels and applications. This report details technical results of the work performed under the following tasks for the SOFC Power System: Task 1 SOFC System Development; Task 2 Solid Oxide Fuel Cell Stack Developments; Task 3 Reformer Developments; Task 4 Development of Balance of Plant Components; Task 5 Project Management; and Task 6 System Modeling & Cell Evaluation for High Efficiency Coal-Based Solid Oxide Fuel Cell Gas Turbine Hybrid System.

  15. FRACTURE FAILURE CRITERIA OF SOFC PEN STRUCTURE

    SciTech Connect

    Liu, Wenning N.; Sun, Xin; Khaleel, Mohammad A.; Qu, Jianmin

    2007-04-30

    Thermal stresses and warpage of the PEN are unavoidable due to the temperature changes from the stress-free sintering temperature to room temperature and mismatch of the coefficients of thermal expansion (CTE) of various layers in the PEN structures of solid oxide fuel cells (SOFC) during the PEN manufacturing process. In the meantime, additional mechanical stresses will also be created by mechanical flattening during the stack assembly process. The porous nature of anode and cathode in the PEN structures determines presence of the initial flaws and crack on the interfaces of anode/electrolyte/cathode and in the interior of the materials. The sintering/assembling induced stresses may cause the fracture failure of PEN structure. Therefore, fracture failure criteria for SOFC PEN structures is developed in order to ensure the structural integrity of the cell and stack of SOFC. In this paper, the fracture criteria based on the relationship between the critical energy release rate and critical curvature and maximum displacement of the warped cells caused by the temperature changes as well as mechanical flattening process is established so that possible failure of SOFC PEN structures may be predicted deterministically by the measurement of the curvature and displacement of the warped cells.

  16. Characterization of ceria-based SOFCs

    SciTech Connect

    Doshi, R.; Roubort, J.; Krumpelt, M.

    1996-12-31

    Solid Oxide Fuel Cells (SOFCs) operating at low temperatures (500-700 C) offer many advantages over conventional zirconia-based fuel cells operating at higher temperatures. Cathode performance is being improved by using better materials and/or microstructures. Fabrication of thin dense electrolytes is also necessary to achieve high cell performances.

  17. Status of SOFC development at Siemens

    SciTech Connect

    Drenckhahn, W.; Blum, L.; Greiner, H.

    1996-12-31

    The Siemens SOFC development programme reached an important milestone in June 1995. A stack operating with hydrogen and oxygen produced a peak power of 10.7 kW at a current density of 0.7 A/cm{sup 2} and was running for more than 1400 hours. The SOFC configuration is based on a flat metal separator plate using the multiple cell array design. Improved PENs, functional layer and joining technique were implemented. Based on this concept, a 100 kW plant was designed The SOFC development at Siemens has been started in 1990 after a two years preparation phase. The first period with the goal of the demonstration of a 1 kW SOFC stack operation ended in 1993. This important milestone was finally reached in the begin of 1994. The second project phase with the final milestone of a 20 kW module operation will terminate at the end of 1996. This result will form a basis for the next phase in which a 50 to 100 kW pilot plant will be built and tested.

  18. Status of the TMI SOFC system

    SciTech Connect

    Ruhl, R.C.; Petrik, M.A.; Cable, T.L.

    1996-12-31

    TMI has completed preliminary engineering designs for complete 20kW SOFC systems modules for stationary distributed generation applications using pipeline natural gas [sponsored by Rochester Gas and Electric (Rochester, New York) and EPRI (Palo Alto, California)]. Subsystem concepts are currently being tested.

  19. Tubular toxicity of proteinuria.

    PubMed

    Baines, Richard J; Brunskill, Nigel J

    2011-03-01

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

  20. SOFC system with integrated catalytic fuel processing

    NASA Astrophysics Data System (ADS)

    Finnerty, Caine; Tompsett, Geoff. A.; Kendall, Kevin; Ormerod, R. Mark

    In recent years, there has been much interest in the development of solid oxide fuel cell technology operating directly on hydrocarbon fuels. The development of a catalytic fuel processing system, which is integrated with the solid oxide fuel cell (SOFC) power source is outlined here. The catalytic device utilises a novel three-way catalytic system consisting of an in situ pre-reformer catalyst, the fuel cell anode catalyst and a platinum-based combustion catalyst. The three individual catalytic stages have been tested in a model catalytic microreactor. Both temperature-programmed and isothermal reaction techniques have been applied. Results from these experiments were used to design the demonstration SOFC unit. The apparatus used for catalytic characterisation can also perform in situ electrochemical measurements as described in previous papers [C.M. Finnerty, R.H. Cunningham, K. Kendall, R.M. Ormerod, Chem. Commun. (1998) 915-916; C.M. Finnerty, N.J. Coe, R.H. Cunningham, R.M. Ormerod, Catal. Today 46 (1998) 137-145]. This enabled the performance of the SOFC to be determined at a range of temperatures and reaction conditions, with current output of 290 mA cm -2 at 0.5 V, being recorded. Methane and butane have been evaluated as fuels. Thus, optimisation of the in situ partial oxidation pre-reforming catalyst was essential, with catalysts producing high H 2/CO ratios at reaction temperatures between 873 K and 1173 K being chosen. These included Ru and Ni/Mo-based catalysts. Hydrocarbon fuels were directly injected into the catalytic SOFC system. Microreactor measurements revealed the reaction mechanisms as the fuel was transported through the three-catalyst device. The demonstration system showed that the fuel processing could be successfully integrated with the SOFC stack.

  1. Effect of nickel impregnated hollow fiber anode for micro tubular solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    He, Beibei; Ling, Yihan; Xu, Jianmei; Zhao, Ling; Cheng, Jigui

    2014-07-01

    A micro tubular solid oxide fuel cells (MT-SOFCs) with a cell configuration of Ni impregnated Ni-Gd0.1Ce0.9O1.95 (GDC)/GDC/La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF)-GDC has been prepared by the phase inversion and impregnation technique. A special asymmetrical structure consisting of a sponge-like layer and a finger-like porous layer for hollow fiber anode is obtained by the phase inversion. Fine Ni specie particles are then coated on the surface of anode using impregnation method. The enhancement in electronic conductivity of anode by Ni modification is beneficial to current collection of MT-SOFCs. Meanwhile, the catalytic activity of anode is also improved due to the introduction of Ni nano-particles. Thus, the Ni modified MT-SOFCs exhibit high power densities, such as 0.69 W cm-2 at 600 °C. The encouraging results demonstrate that the Ni impregnation is an effective way to improve anode microstructure of MT-SOFCs.

  2. High-fidelity stack and system modeling for tubular solid oxide fuel cell system design and thermal management

    NASA Astrophysics Data System (ADS)

    Kattke, K. J.; Braun, R. J.; Colclasure, A. M.; Goldin, G.

    Effective thermal integration of system components is critical to the performance of small-scale (<10 kW) solid oxide fuel cell systems. This paper presents a steady-state design and simulation tool for a highly-integrated tubular SOFC system. The SOFC is modeled using a high fidelity, one-dimensional tube model coupled to a three-dimensional computational fluid dynamics (CFD) model. Recuperative heat exchange between SOFC tail-gas and inlet cathode air and reformer air/fuel preheat processes are captured within the CFD model. Quasi one-dimensional thermal resistance models of the tail-gas combustor (TGC) and catalytic partial oxidation (CPOx) complete the balance of plant (BoP) and SOFC coupling. The simulation tool is demonstrated on a prototype 66-tube SOFC system with 650 W of nominal gross power. Stack cooling predominately occurs at the external surface of the tubes where radiation accounts for 66-92% of heat transfer. A strong relationship develops between the power output of a tube and its view factor to the relatively cold cylinder wall surrounding the bundle. The bundle geometry yields seven view factor groupings which correspond to seven power groupings with tube powers ranging from 7.6-10.8 W. Furthermore, the low effectiveness of the co-flow recuperator contributes to lower tube powers at the bundle outer periphery.

  3. 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.

  4. Siemens SOFC Test Article and Module Design

    SciTech Connect

    2011-03-31

    Preliminary design studies of the 95 kWe-class SOFC test article continue resulting in a stack architecture of that is 1/3 of 250 kWe-class SOFC advanced module. The 95 kWeclass test article is envisioned to house 20 bundles (eight cells per bundle) of Delta8 cells with an active length of 100 cm. Significant progress was made in the conceptual design of the internal recirculation loop. Flow analyses were initiated in order to optimize the bundle row length for the 250 kWeclass advanced module. A preferred stack configuration based on acceptable flow and thermal distributions was identified. Potential module design and analysis issues associated with pressurized operation were identified.

  5. Considerations of Glass Sealing SOFC Stacks

    SciTech Connect

    Yang, Z Gary; Weil, K. Scott; Meinhardt, Kerry D.; Paxton, Dean M.; Stevenson, Jeffry W.

    2003-08-31

    Due to their TEC matching to PEN components, excellent oxidation resistance, low cost and good fabricability, stainless steels have been used as the interconnect materials in planar SOFC. For being hermetical, the stainless steel interconnect ought to be sealed to YSZ electrolyte and/or another piece of metallic interconnect, usually using a sealing glass. The seal performance, which is critical factor to determine the reliability and durability of SOFC stack, largely depends on the chemical compatibility between the sealing glass and stainless steel. In this work, the ferritic stainless steel 446 and a barium-aluminosilicate base glass have been taken as an example for metallic interconnects and sealing glass, respectively, and the corrosion at the interface of metal and sealing glass has been investigated and understood. The methodology and results of the microscopic analysis and thermodynamic modeling will be presented, and the mechanism of corrosion at the interface will be discussed as well.

  6. SOFC cells and stacks for complex fuels

    SciTech Connect

    Edward M. Sabolsky; Matthew Seabaugh; Katarzyna Sabolsky; Sergio A. Ibanez; Zhimin Zhong

    2007-07-01

    Reformed hydrocarbon and coal (syngas) fuels present an opportunity to integrate solid oxide fuel cells into the existing fuel infrastructure. However, these fuels often contain impurities or additives that may lead to cell degradation through sulfur poisoning or coking. Achieving high performance and sulfur tolerance in SOFCs operating on these fuels would simplify system balance of plant and sequestration of anode tail gas. NexTech Materials, Ltd., has developed a suite of materials and components (cells, seals, interconnects) designed for operation in sulfur-containing syngas fuels. These materials and component technologies have been integrated into an SOFC stack for testing on simulated propane, logistic fuel reformates and coal syngas. Details of the technical approach, cell and stack performance is reported.

  7. Status of SOFCo SOFC technology development

    SciTech Connect

    Privette, R.; Perna, M.A.; Kneidel, K.

    1996-12-31

    SOFCo, a Babcock & Wilcox/Ceramatec Research & Development Limited Partnership, is a collaborative research and development venture to develop technologies related to planar, solid-oxide fuel cells (SOFCs). SOFCo has successfully demonstrated a kW-class, solid-oxide fuel cell module operating on pipeline natural gas. The SOFC system design integrates the air preheater and the fuel processor with the fuel cell stacks into a compact test unit; this is the platform for multi-kW modules. The cells, made of tape-cast zirconia electrolyte and conventional electrode materials, exhibit excel lent stability in single-cell tests approaching 40,000 hours of operation. Stack tests using 10-cm and 15-cm cells with ceramic interconnects also show good performance and stability in tests for many thousands of hours.

  8. Compressive Mica Seals for SOFC Applications

    SciTech Connect

    Simner, Steve P.; Stevenson, Jeffry W.

    2001-09-30

    Muscovite and phlogopite micas have been assessed as SOFC seals at 800 C. Paper gaskets, composed of pressed mica platelets in an organic binder, proved ineffective seal materials predominantly because of their uneven surface. However, cleaved natural mica sheets (with no binder) indicated far superior sealing characteristics with leak rates lower than 0.1 sccm.cm-1 at 800 C, and approximately 0.7 MPa (100 psi) compressive stress.

  9. Compressive Mica Seals for SOFC Applications

    SciTech Connect

    Simner, Steve P.; Stevenson, Jeffry W.

    2001-08-01

    Muscovite and phlogopite micas have been assessed as SOFC seals at 800C. Paper gaskets, composed of pressed mica platelets in an organic binder, proved ineffective seal materials predominantly because of their uneven surface. However, cleaved natural mica sheets (with no binder) indicated far superior sealing characteristics with leak rates lower than 0.1 sccm. cm-1 at 800C, and approximately 0.7 MPa (100 psi) compressive stress.

  10. Formulating liquid hydrocarbon fuels for SOFCs

    NASA Astrophysics Data System (ADS)

    Saunders, G. J.; Preece, J.; Kendall, K.

    The injection of liquid hydrocarbons directly into an SOFC system is considered for application to hybrid vehicles. The main problem is carbon deposition on the nickel anode when molecules such as ethanol or iso-octane are injected directly. Such carbon deposition has been studied using a microtubular SOFC with a mass spectrometer analysing the product gases to investigate the reaction sequence and also to investigate the deposited carbon by temperature programmed oxidation (TPO). The results show that only two liquids could be injected directly onto nickel cermet anodes without serious carbon blockage, methanol and methanoic acid. Even then, TPO experiments revealed deposition of small amounts of carbon which could be prevented by small additions of air or water to the fuel. Gasoline type molecules like iso-octane killed the SOFC in about 30 min operation, with about 90% of the molecular carbon being deposited on the nickel cermet anode. However, certain mixtures of iso-octane, water, alcohol and surfactant were found to produce beneficial results with remarkably low carbon deposition, less than 1% of the molecular carbon appearing on the anode. Such formulations had octane numbers appropriate to internal combustion engine operation.

  11. Development of 5kW class MOLB type SOFC

    SciTech Connect

    Hattori, M.; Esaki, Y.; Sakaki, Y.

    1996-12-31

    Fuel cell development has been accelerated in recent years primarily due to its high efficiency and minimum environmental effect. Especially SOFC is receiving greater attention due to its excellent characteristics. Among several types of SOFC, MOLB (MOno block Layer Built) type SOFC provides following advantages for a large scale power plant; (1) Suitable for mass production, and (2) able to obtain high power density. Chubu Electric Power Company, Inc. (CEPCO) and Mitsubishi Heavy Industries, LTD. (MHI) have jointly developed and evaluated the MOLB type SOFC on since 1990. This paper presents recent progress on it.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Development of Ceramic Interconnect Materials for SOFC

    SciTech Connect

    Yoon, Kyung J.; Stevenson, Jeffry W.; Marina, Olga A.

    2010-08-05

    Currently, acceptor-doped lanthanum chromite is the state-of-the-art ceramic interconnect material for high temperature solid oxide fuel cells (SOFCs) due to its fairly good electronic conductivity and chemical stability in both oxidizing and reducing atmospheres, and thermal compatibility with other cell components. The major challenge for acceptor-doped lanthanum chromite for SOFC interconnect applications is its inferior sintering behavior in air, which has been attributed to the development of a thin layer of Cr2O3 at the interparticle necks during the initial stages of sintering. In addition, lanthanum chromite is reactive with YSZ electrolyte at high temperatures, forming a highly resistive lanthanum zirconate phase (La2Zr2O7), which further complicates co-firing processes. Acceptor-doped yttrium chromite is considered to be one of the promising alternatives to acceptor-doped lanthanum chromite because it is more stable with respect to the formation of hydroxides in SOFC operating conditions, and the formation of impurity phases can be effectively avoided at co-firing temperatures. In addition, calcium-doped yttrium chromite exhibits higher mechanical strength than lanthanum chromite-based materials. The major drawback of yttrium chromite is considered to be its lower electrical conductivity than lanthanum chromite. The properties of yttrium chromites could possibly be improved and optimized by partial substitution of chromium with various transition metals. During FY10, PNNL investigated the effect of various transition metal doping on chemical stability, sintering and thermal expansion behavior, microstructure, electronic and ionic conductivity, and chemical compatibility with other cell components to develop the optimized ceramic interconnect material.

  17. Mica-based Composite Compressive Seals for SOFC

    SciTech Connect

    Chou, Y S.; Meinhardt, Kerry D.; Stevenson, Jeffry W.; Singh, Prabhakar

    2004-07-07

    One of the critical challenges facing planar solid oxide fuel cell (SOFC) technology is the need for reliable sealing technology. Seals are required for long-term stability and integrity in the high temperature SOFC environment during normal and transient operations. Several different approaches for sealing SOFC stacks are under development, including glass or glass-ceramic seals, metallic brazes, and compressive seals. Compressive seals potentially offer a significant and unique advantage over the other approaches by providing a means of mechanically ''de-coupling'' adjacent stack components, thereby minimizing the need for closely matching the coefficients of thermal expansion (CTE) of the various SOFC stack components. In an attempt to help the SOFC industry overcome sealing challenges, PNNL is developing mica-based hybrid compressive seals which exhibit leak rates 2 to 3 orders of magnitude lower than obtained with simple mica gasket seals.

  18. Experimental analysis of performance degradation of micro-tubular solid oxide fuel cells fed by different fuel mixtures

    NASA Astrophysics Data System (ADS)

    Calise, F.; Restucccia, G.; Sammes, N.

    This paper analyzes the thermodynamic and electrochemical dynamic performance of an anode supported micro-tubular solid oxide fuel cell (SOFC) fed by different types of fuel. The micro-tubular SOFC used is anode supported, consisting of a NiO and Gd 0.2Ce 0.8O 2- x (GDC) cermet anode, thin GDC electrolyte, and a La 0.6Sr 0.4Co 0.2Fe 0.8O 3- y (LSCF) and GDC cermet cathode. The fabrication of the cells under investigation is briefly summarized, with emphasis on the innovations with respect to traditional techniques. Such micro-tubular cells were tested using a Test Stand consisting of: a vertical tubular furnace, an electrical load, a galvanostast, a bubbler, gas pipelines, temperature, pressure and flow meters. The tests on the micro-SOFC were performed using H 2, CO, CH 4 and H 2O in different combinations at 550 °C, to determine the cell polarization curves under several load cycles. Long-term experimental tests were also performed in order to assess degradation of the electrochemical performance of the cell. Results of the tests were analyzed aiming at determining the sources of the cell performance degradation. Authors concluded that the cell under investigation is particularly sensitive to the carbon deposition which significantly reduces cell performance, after few cycles, when fed by light hydrocarbons. A significant performance degradation is also detected when hydrogen is used as fuel. In this case, the authors ascribe the degradation to the micro-cracks, the change in materials crystalline structure and problems with electrical connections.

  19. A 2D transient numerical model combining heat/mass transport effects in a tubular solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Mollayi Barzi, Y.; Ghassemi, M.; Hamedi, M. H.

    The purpose of this study is to present a 2D transient numerical model to predict the dynamic behavior of a tubular SOFC. In this model, the transient conservation equations (momentum, species and energy equations) are solved numerically and electrical and electrochemical outputs are calculated with an equivalent electrical circuit for the cell. The developed model determines the cell electrical and thermal responses to the variation of load current. Also it predicts the local EMF, state variables (pressure, temperature and species concentration) and cell performance for different cell load currents. Using this comprehensive model the dynamic behavior of Tubular SOFC is studied. First an initial steady state operating condition is set for the SOFC model and then the time response of the fuel cell to changes of some interested input parameters (like electrical load) is analyzed. The simulation starts when the cell is at the steady state in a specific output load. When the load step change takes place, the solution continues to reach to the new steady state condition. Then the cell transient behavior is analyzed. The results show that when the load current is stepped up, the output voltage decreases to a new steady state voltage in about 67 min.

  20. Analysis of SOFCs Using Reference Electrodes

    SciTech Connect

    Finklea, H.; Chen, X.; Gerdes, K.; Pakalapati, S.; Celik, I.

    2013-01-01

    Reference electrodes are frequently applied to isolate the performance of one electrode in a solid oxide fuel cell. However, reference electrode simulations raise doubt to veracity of data collected using reference electrodes. The simulations predict that the reported performance for the one electrode will frequently contain performance of both electrodes. Nonetheless, recent reports persistently treat data so collected as ideally isolated. This work confirms the predictions of the reference electrode simulations on two SOFC designs, and to provides a method of validating the data measured in the 3-electrode configuration. Validation is based on the assumption that a change in gas composition to one electrode does not affect the impedance of the other electrode at open circuit voltage. This assumption is supported by a full physics simulation of the SOFC. Three configurations of reference electrode and cell design are experimentally examined using various gas flows and two temperatures. Impedance data are subjected to deconvolution analysis and equivalent circuit fitting and approximate polarization resistances of the cathode and anode are determined. The results demonstrate that the utility of reference electrodes is limited and often wholly inappropriate. Reported impedances and single electrode polarization values must be scrutinized on this basis.

  1. Solid State Energy Conversion Alliance Delphi SOFC

    SciTech Connect

    Steven Shaffer; Sean Kelly; Larry Chick; Subhasish Mukerjee; David Schumann

    2003-05-20

    The objective of Phase I under this project is to develop a 5 kW SOFC power system for a range of fuels and applications. During Phase I, the following will be accomplished: 1. Develop and demonstrate technology transfer efforts on a 5 kW stationary distributed power generation system that incorporates steam reforming of natural gas with piped-in water (Demonstration System A). 2. Initiate development of a 5 kW system for later mass-market automotive auxiliary power unit application, which will incorporate catalytic partial oxidation (CPO) reforming of gasoline, with anode exhaust gas injected into an ultra-lean burn internal combustion engine. This topical report covers work performed by Delphi Automotive Systems from January through June 2002 under DOE Cooperative Agreement DE-FC-02NT41246 for the 5 kW mass-market automotive (gasoline) auxiliary power unit. This report highlights technical results of the work performed under the following tasks for the automotive 5 kW system: 1. System Design and Integration 2. SOFC Stack Development 3. Reformer Development The next anticipated Technical Progress Report will be submitted January 30, 2003 and will include tasks contained within the cooperative agreement including development work on the Demonstration System A, if available.

  2. Heat removal from high temperature tubular solid oxide fuel cells utilizing product gas from coal gasifiers.

    SciTech Connect

    Parkinson, W. J. ,

    2003-01-01

    In this work we describe the results of a computer study used to investigate the practicality of several heat exchanger configurations that could be used to extract heat from tubular solid oxide fuel cells (SOFCs) . Two SOFC feed gas compositions were used in this study. They represent product gases from two different coal gasifier designs from the Zero Emission Coal study at Los Alamos National Laboratory . Both plant designs rely on the efficient use of the heat produced by the SOFCs . Both feed streams are relatively rich in hydrogen with a very small hydrocarbon content . One feed stream has a significant carbon monoxide content with a bit less hydrogen . Since neither stream has a significant hydrocarbon content, the common use of the endothermic reforming reaction to reduce the process heat is not possible for these feed streams . The process, the method, the computer code, and the results are presented as well as a discussion of the pros and cons of each configuration for each process .

  3. Diesel Fueled SOFC for Class 7/Class 8 On-Highway Truck Auxiliary Power

    SciTech Connect

    Vesely, Charles John-Paul; Fuchs, Benjamin S.; Booten, Chuck W.

    2010-03-31

    The following report documents the progress of the Cummins Power Generation (CPG) Diesel Fueled SOFC for Class 7/Class 8 On-Highway Truck Auxiliary Power (SOFC APU) development and final testing under the U.S. Department of Energy (DOE) Energy Efficiency and Renewable Energy (EERE) contract DE-FC36-04GO14318. This report overviews and summarizes CPG and partner development leading to successful demonstration of the SOFC APU objectives and significant progress towards SOFC commercialization. Significant SOFC APU Milestones: Demonstrated: Operation meeting SOFC APU requirements on commercial Ultra Low Sulfur Diesel (ULSD) fuel. SOFC systems operating on dry CPOX reformate. Successful start-up and shut-down of SOFC APU system without inert gas purge. Developed: Low cost balance of plant concepts and compatible systems designs. Identified low cost, high volume components for balance of plant systems. Demonstrated efficient SOFC output power conditioning. Demonstrated SOFC control strategies and tuning methods.

  4. Device for inserting tubular members together

    SciTech Connect

    Milberger, L.J.

    1992-03-17

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

  5. An Integrated Approach to Modeling and Mitigating SOFC Failure

    SciTech Connect

    Fedorov, A.; Haynes, C.; Qu, J.

    2005-01-27

    The objective of this project is to develop first-order failure criteria to be used for the initial design, material selection and optimization against thermomechanical failure of the PEN structure in high temperature SOFCs.

  6. Cassette less SOFC stack and method of assembly

    SciTech Connect

    Meinhardt, Kerry D

    2014-11-18

    A cassette less SOFC assembly and a method for creating such an assembly. The SOFC stack is characterized by an electrically isolated stack current path which allows welded interconnection between frame portions of the stack. In one embodiment electrically isolating a current path comprises the step of sealing a interconnect plate to a interconnect plate frame with an insulating seal. This enables the current path portion to be isolated from the structural frame an enables the cell frame to be welded together.

  7. Nondestructive cell evaluation techniques in SOFC stack manufacturing

    NASA Astrophysics Data System (ADS)

    Wunderlich, C.

    2016-04-01

    Independent from the specifics of the application, a cost efficient manufacturing of solid oxide fuel cells (SOFC), its electrolyte membranes and other stack components, leading to reliable long-life stacks is the key for the commercial viability of this fuel cell technology. Tensile and shear stresses are most critical for ceramic components and especially for thin electrolyte membranes as used in SOFC cells. Although stack developers try to reduce tensile stresses acting on the electrolyte by either matching CTE of interconnects and electrolytes or by putting SOFC cells under some pressure - at least during transient operation of SOFC stacks ceramic cells will experience some tensile stresses. Electrolytes are required to have a high Weibull characteristic fracture strength. Practical experiences in stack manufacturing have shown that statistical fracture strength data generated by tests of electrolyte samples give limited information on electrolyte or cell quality. In addition, the cutting process of SOFC electrolytes has a major influence on crack initiation. Typically, any single crack in one the 30 to 80 cells in series connection will lead to a premature stack failure drastically reducing stack service life. Thus, for statistical reasons only 100% defect free SOFC cells must be assembled in stacks. This underlines the need for an automated inspection. So far, only manual processes of visual or mechanical electrolyte inspection are established. Fraunhofer IKTS has qualified the method of optical coherence tomography for an automated high throughput inspection. Alternatives like laser speckle photometry and acoustical methods are still under investigation.

  8. Modelling of tubular-designed solid oxide fuel cell with indirect internal reforming operation fed by different primary fuels

    NASA Astrophysics Data System (ADS)

    Dokmaingam, P.; Assabumrungrat, S.; Soottitantawat, A.; Laosiripojana, N.

    Mathematical models of an indirect internal reforming solid oxide fuel cell (IIR-SOFC) fed by four different primary fuels, i.e., methane, biogas, methanol and ethanol, are developed based on steady-state, heterogeneous, two-dimensional and tubular-design SOFC models. The effect of fuel type on the thermal coupling between internal endothermic reforming with exothermic electrochemical reactions and system performance are determined. The simulation reveals that an IIR-SOFC fuelled by methanol provides the smoothest temperature gradient with high electrochemical efficiency. Furthermore, the content of CO 2 in biogas plays an important role on system performance since electrical efficiency is improved by the removal of some CO 2 from biogas but a larger temperature gradient is expected. Sensitivity analysis of three parameters, namely, a operating pressure, inlet steam to carbon (S:C) ratio and flow direction is then performed. By increasing the operating pressure up to 10 bar, the system efficiency increases and the temperature gradient can be minimized. The use of a high inlet S:C ratio reduces the cooling spot at the entrance of reformer channel but the electrical efficiency is considerably decreased. An IIR-SOFC with a counter-flow pattern (as based case) is compared with that with co-flow pattern (co-flow of air and fuel streams through fuel cell). The IIR-SOFC with co-flow pattern provides higher voltage and a smoother temperature gradient along the system due to superior matching between heat supplied from electrochemical reaction and heat required for steam reforming reaction; thus it is expected to be a better option for practical applications.

  9. 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)

  10. Tubular cystourethroneostomy after total prostatectomy.

    PubMed

    Melchior, H

    1975-01-01

    After radical prostatectomy cystourethroneostomy is done as a tubular cystourethroplasty. In the last 13 months 14 patients have been operated on in this manner. In 12 patients continence was achieved; 2 patients had a temporary stress incontinence. The stress incontinence could be treated successfully by temporary electrostimulation of the pelvic floor by an anal plug stimulator.

  11. 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.

  12. Direct reforming of biogas on Ni-based SOFC anodes: Modelling of heterogeneous reactions and validation with experiments

    NASA Astrophysics Data System (ADS)

    Santarelli, Massimo; Quesito, Francesco; Novaresio, Valerio; Guerra, Cosimo; Lanzini, Andrea; Beretta, Davide

    2013-11-01

    This work focuses on the heterogeneous reactions taking place in a tubular anode-supported solid oxide fuel cell (SOFC) when the designated fuel is biogas from anaerobic digestion directly feeding the fuel cell. Operational maps of the fuel cell running on direct reforming of biogas were first obtained. Hence a mathematical model incorporating the kinetics of reforming reactions on Ni catalyst was used to predict the gas composition profile along the fuel channel. The model was validated against experimental data based on polarization curves. Also, the anode off-gas composition was collected and analyzed through a gas chromatograph. Finally, the model has been used to predict and analyze the gas composition change along the anode channel to evaluate effectiveness of the direct steam reforming when varying cell temperature, inlet fuel composition and the type of reforming process. The simulations results confirmed that thermodynamic-equilibrium conditions are not fully achieved inside the anode channel. It also outlines that a direct biogas utilization in an anode-supported SOFC is able to provide good performance and to ensure a good conversion of the methane even though when the cell temperature is far from the nominal value.

  13. Thermoeconomic modeling and parametric study of hybrid SOFC-gas turbine-steam turbine power plants ranging from 1.5 to 10 MWe

    NASA Astrophysics Data System (ADS)

    Arsalis, Alexandros

    Detailed thermodynamic, kinetic, geometric, and cost models are developed, implemented, and validated for the synthesis/design and operational analysis of hybrid SOFC-gas turbine-steam turbine systems ranging in size from 1.5 to 10 MWe. The fuel cell model used in this research work is based on a tubular Siemens-Westinghouse-type SOFC, which is integrated with a gas turbine and a heat recovery steam generator (HRSG) integrated in turn with a steam turbine cycle. The current work considers the possible benefits of using the exhaust gases in a HRSG in order to produce steam which drives a steam turbine for additional power output. Four different steam turbine cycles are considered in this research work: a single-pressure, a dual-pressure, a triple pressure, and a triple pressure with reheat. The models have been developed to function both at design (full load) and off-design (partial load) conditions. In addition, different solid oxide fuel cell sizes are examined to assure a proper selection of SOFC size based on efficiency or cost. The thermoeconomic analysis includes cost functions developed specifically for the different system and component sizes (capacities) analyzed. A parametric study is used to determine the most viable system/component syntheses/designs based on maximizing total system efficiency or minimizing total system life cycle cost.

  14. Development status of planar SOFCs at Sanyo

    SciTech Connect

    Miyake, Yasuo; Akiyama, Yukinori; Yasuo, Takashi

    1996-12-31

    A 2 kW class combined cell stacked module (182 cm{sup 2} X 4X 17) was examined. An output power of 2.47 kW and output power density of 0.20 W/cm{sup 2} were obtained at the current density of 0.3 A/cm{sup 2}. The temperature uniformity is an important factor to develop large scale SOFC modules. Therefore, in this 2 kW class module, one cell was divided into four smaller unit cells to decrease temperature difference across these cells. Moreover, an internal heat-exchanging duct was arranged to spend the surplus heat effectively in the middle of the module. As for the basic research, the followings were investigated to improve thermal cycle characteristics. One was to adopt a silica/alumina-based sealing, material in order to absorb the thermal expansion difference between the electrolyte and the separator. Deterioration was quite small after 12 thermal cycles with a 150 by 150 mm single cell. The other was to use a heat-resisting ferritic alloy as a separator in a 50 by 50 mm single cell in order to decrease the thermal expansion coefficient of the separator. High performance was obtained for 2000 hours at 900{degrees}C in an endurance test and deterioration was quite small after a thermal cycle.

  15. Characterization of ceria-based SOFCs

    SciTech Connect

    Doshi, R.; Routbort, J.; Krumpelt, M.

    1996-12-31

    Solid Oxide Fuel Cells (SOFCs) operating at low temperatures (500-700{degrees}C) offer many advantages over the conventional zirconia-based fuel cells operating at higher temperatures. Reduced operating temperatures result in: (1) Application of metallic interconnects with reduced oxidation problems (2) Reduced time for start-up and lower energy consumption to reach operating temperatures (3) Increased thermal cycle ability for the cell structure due to lower thermal stresses of expansion mismatches. While this type of fuel cell may be applied to stationary applications, mobile applications require the ability for rapid start-up and frequent thermal cycling. Ceria-based fuel cells are currently being developed in the U.K. at Imperial College, Netherlands at ECN, and U.S.A. at Ceramatec. The cells in each case are made from a doped ceria electrolyte and a La{sub 1-x}Sr{sub x}Co{sub 1-y}Fe{sub y}O{sub 3} cathode.

  16. Development of cofired type planar SOFC

    SciTech Connect

    Taira, Hiroaki; Sakamoto, Sadaaki; Zhou, Hua-Bing

    1996-12-31

    We have developed fabrication process for planar SOFC fabricated with cofired anode/electrolyte/cathode multilayers and interconnects. By cofiring technique for the multilayers, we expect to reduce the thickness of the electrolyte layers, resulting in decrease of innerimpedance, and achieve low production cost. On the other hand, the cofiring technique requires that the sintering temperature, the shrinkage profiles and the thermal expansion characteristics of all component materials should be compatible with the other. It is, therefore, difficult to cofire the multilayers with large area. Using the multilayers with surface area of 150cm{sup 2}, we fabricated the multiple cell stacks. The maximum power of 5x4 multiple cell stack (5 planes of cells in series, 4 cells in parallel in each planes 484cm{sup 2} effective electrode area of each cell planes) was 601W (0.25Wcm{sup -2}, Uf=40%). However, the terminal voltage of the multiple cell stack decreased by the cause of cell cracking, gas leakage and degradation of cofired multilayers. This paper presents the improvements of cofired multilayers, and the performance of multiple cell stacks with the improved multilayers.

  17. Testing of a cathode fabricated by painting with a brush pen for anode-supported tubular solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Liu, Renzhu; Zhao, Chunhua; Li, Junliang; Wang, Shaorong; Wen, Zhaoyin; Wen, Tinglian

    We have studied the properties of a cathode fabricated by painting with a brush pen for use with anode-supported tubular solid oxide fuel cells (SOFCs). The porous cathode connects well with the electrolyte. A preliminary examination of a single tubular cell, consisting of a Ni-YSZ anode support tube, a Ni-ScSZ anode functional layer, a ScSZ electrolyte film, and a LSM-ScSZ cathode fabricated by painting with a brush pen, has been carried out, and an improved performance is obtained. The ohmic resistance of the cathode side clearly decreases, falling to a value only 37% of that of the comparable cathode made by dip-coating at 850 °C. The single cell with the painted cathode generates a maximum power density of 405 mW cm -2 at 850 °C, when operating with humidified hydrogen.

  18. 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.

  19. Synchrotron Investigations of SOFC Cathode Degradation

    SciTech Connect

    Idzerda, Yves

    2013-09-30

    The atomic variations occurring in cathode/electrolyte interface regions of La{sub 1-x}Sr{sub x}Co{sub y}Fe{sub 1-y}O{sub 3-δ} (LSCF) cathodes and other SOFC related materials have been investigated and characterized using soft X-ray Absorption Spectroscopy (XAS) and diffuse soft X-ray Resonant Scattering (XRS). X-ray Absorption Spectroscopy in the soft X-ray region (soft XAS) is shown to be a sensitive technique to quantify the disruption that occurs and can be used to suggest a concrete mechanism for the degradation. For LSC, LSF, and LSCF films, a significant degradation mechanism is shown to be Sr out-diffusion. By using the XAS spectra of hexavalent Cr in SrCrO4 and trivalent Cr in Cr2O3, the driving factor for Sr segregation was identified to be the oxygen vacancy concentration at the anode and cathode side of of symmetric LSCF/GDC/LSCF heterostructures. This is direct evidence of vacancy induced cation diffusion and is shown to be a significant indicator of cathode/electrolyte interfacial degradation. X-ray absorption spectroscopy is used to identify the occupation of the A-sites and B-sites for LSC, LSF, and LSCF cathodes doped with other transition metals, including doping induced migration of Sr to the anti-site for Sr, a significant cathode degradation indicator. By using spatially resolved valence mapping of Co, a complete picture of the surface electrochemistry can be determined. This is especially important in identifying degradation phenomena where the degradation is spatially localized to the extremities of the electrochemistry and not the average. For samples that have electrochemical parameters that are measured to be spatially uniform, the Co valence modifications were correlated to the effects of current density, overpotential, and humidity.

  20. Effects of composition on sintering of current interconnects in SOFC

    SciTech Connect

    Chick, L.A.; Bates, J.L.

    1992-11-01

    The sintering behavior of alkaline-earth-substituted lanthanum and yttrium chromites, which are candidates for the current interconnect in solid oxide fuel cells (SOFC) was investigated. Extensive commercialization of SOFC technology may involve co-sintering as a method to reduce production costs. Co-sintering will require that the interconnect material reaches high density (closed porosity) under conditions in which the air-electrode material, a manganite, maintains substantial porosity and remains stable. Therefore, ideal chromite compositions are those that attain greater than 94% of theoretical density in high PO{sub 2} atmosphere at temperatures near or below 1400{degree}C.

  1. Effects of composition on sintering of current interconnects in SOFC

    SciTech Connect

    Chick, L.A.; Bates, J.L.

    1992-11-01

    The sintering behavior of alkaline-earth-substituted lanthanum and yttrium chromites, which are candidates for the current interconnect in solid oxide fuel cells (SOFC) was investigated. Extensive commercialization of SOFC technology may involve co-sintering as a method to reduce production costs. Co-sintering will require that the interconnect material reaches high density (closed porosity) under conditions in which the air-electrode material, a manganite, maintains substantial porosity and remains stable. Therefore, ideal chromite compositions are those that attain greater than 94% of theoretical density in high PO[sub 2] atmosphere at temperatures near or below 1400[degree]C.

  2. Corrosion Performance of Ferritic Steel for SOFC Interconnect Applications

    SciTech Connect

    Ziomek-Moroz, M.; Holcomb, G.R.; Covino, B.S., Jr.; Bullard, S.J.; Jablonski, P.D.; Alman, D.E.

    2006-11-01

    Ferritic stainless steels have been identified as potential candidates for interconnects in planar-type solid oxide fuel cells (SOFC) operating below 800ºC. Crofer 22 APU was selected for this study. It was studied under simulated SOFC-interconnect dual environment conditions with humidified air on one side of the sample and humidified hydrogen on the other side at 750ºC. The surfaces of the oxidized samples were studied by scanning electron microscopy (SEM) equipped with microanalytical capabilities. X-ray diffraction (XRD) analysis was also used in this study.

  3. Modeling a 5 kWe planar solid oxide fuel cell based system operating on JP-8 fuel and a comparison with tubular cell based system for auxiliary and mobile power applications

    NASA Astrophysics Data System (ADS)

    Tanim, Tanvir; Bayless, David J.; Trembly, Jason P.

    2014-01-01

    A steady state planar solid oxide fuel cell (P-SOFC) based system operating on desulfurized JP-8 fuel was modeled using Aspen Plus simulation software for auxiliary and mobile power applications. An onboard autothermal reformer (ATR) employed to reform the desulfurized JP-8 fuel was coupled with the P-SOFC stack to provide for H2 and CO as fuel, minimizing the cost and complexity associated with hydrogen storage. Characterization of the ATR reformer was conducted by varying the steam to carbon ratio (H2O/C) from 0.1 to 1.0 at different ATR operating temperatures (700-800 °C) while maintaining the P-SOFC stack temperature at 850 °C. A fraction of the anode recycle was used as the steam and heat source for autothermal reforming of the JP-8 fuel, intending to make the system lighter and compact for mobile applications. System modeling revealed a maximum net AC efficiency of 37.1% at 700 °C and 29.2% at 800 °C ATR operating temperatures, respectively. Parametric analyses with respect to fuel utilization factor (Uf) and current density (j) were conducted to determine optimum operating conditions. Finally, the P-SOFC based system was compared with a previously published [1] tubular solid oxide fuel cell based (T-SOFC) system to identify the relative advantages over one another.

  4. 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

  5. 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.

  6. Tubular shear stress and phenotype of renal proximal tubular cells.

    PubMed

    Essig, Marie; Friedlander, Gérard

    2003-06-01

    Phenotypic alterations resulting from flow-induced mechanical strains is a growing field of research in many cell types such as vascular endothelial and smooth muscle cells, chondrocytes, and osteocytes. Because renal mass reduction is followed by a dramatic increase in GFR in the remaining nephron, modulation of tubular cell phenotype by flow-induced mechanical strains could be one of the events initiating the deleterious pathways that lead to the destruction of renal parenchyma after renal mass reduction. This study demonstrates that increased flow induced, in vitro and in vivo, a reinforcement of the apical domain of actin cytoskeleton and an inhibition of plasminogen activator expression. These effects of flow on plasminogen activator expression were prevented by blocking the reorganization of actin cytoskeleton and were associated with an increase in a shear-stress responsive element binding activity. These results confirm that tubular flow affects the phenotype of renal epithelial cells and suggest that flow-induced mechanical strains could be one determinant of tubulointerstitial lesions during the progression of renal diseases. PMID:12761236

  7. Renal tubular secretion of pramipexole.

    PubMed

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

    2015-11-15

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

  8. Downdraft stove with tubular grating

    SciTech Connect

    Zimmerman, H.G.

    1986-08-26

    This patent describes a downdraft stove, a tubular grating assembly for positioning in a reaction chamber which consists of: a substantially vertically oriented central tube open at its upper end and connected at its lower end to an air inlet opening; a cap supported above the open upper end for protecting the open upper end from entry of matter, the space between the cap and the upper end constituting a primary air inlet nozzle; grating tubes radially distributed around and taking off substantially horizontally from and communicating with the central tube, thereby defining a grating, and thence turning downwardly and being open at their downward ends to thereby constitute secondary air inlets.

  9. System to evaluate the performance of insulated tubulars in steam injection wells

    SciTech Connect

    Eisenhawer, S. W.; Johnson, D. R.; Vigil, W. J.

    1981-01-01

    The efficiency of a thermal enhanced oil recovery project with surface steam generation can be significantly increased by using insulated tubing in the injection wells. In order to evaluate the performance of various insulated tubulars it is necessary to obtain detailed temperature measurements and accurate heat loss data under actual in-field conditions. A system to provide this information has been developed and is in operation at the Aberfeldy steam pilot near Lloydminster, Saskatchewan, Canada. Temperature measurements are made using thermocouples inside and on the outer wall of the injection string; on the outside of the casing, and in a set of three 25 mm (1 in.) ID thermowells attached to the casing. In addition, thin film heat flux sensors are bonded directly to the wall of the injection string. A probe system was designed to measure circumferential temperature variations in the thermowells at depths down to 100 m. This makes it possible to obtain detailed axial temperature profiles. Anticipated hot sports on an insulated joint will be detected in this manner. All of the data is recorded on a datalogger and detailed analysis is performed on a computer system. To date a short test has been carried out using bare 60 mm (2-3/8 in.) injection string tubing. This bare string provides data for comparison with insulated strings. High resolution radial temperature profiles were obtained during this test. Variations in heat loss from the string as functions of time and operating conditions have also been successfully monitored. Heat losses from the string during initial start up on the order of 1.0 Kw/m (1050 Btu/hr-ft) were observed with the heat flux sensors. This is in good agreement with the expected heat loss. The heat flux sensors make it possible to both simplify and improve the determination of insulated tubular thermal performance.

  10. 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

  11. Emerin expression in tubular aggregates.

    PubMed

    Manta, Panagiota; Terzis, Gerasimos; Papadimitriou, Constantinos; Kontou, Chrysanthi; Vassilopoulos, Demetris

    2004-06-01

    Emerin is an inner nuclear membrane protein that is mutated or not expressed in patients with X-linked Emery-Dreifuss muscular dystrophy (X-EDMD/EMD). Cytoplasmic localization of emerin in cultured cells or tissues has been reported, although this remains a controversial issue. Tubular aggregates (TAs) are pathological structures seen in the sarcoplasm of human skeletal muscle fibers in various disorders. The TAs derive from the sarcoplasmic reticulum (SR) and represent, probably, an adaptive response of the SR to various insults to the muscle fibers. In the present study, we present immunohistochemical evidence of emerin expression in TAs. Muscle biopsies with tubular aggregates from four male, unrelated patients were studied. The percentage of muscle fibers containing TAs varied between 5 and 20%. Routine histochemistry revealed intense reaction of TAs with NADH-TR, AMPDA, and NSE, but not with COX, SDH, myosin ATPase (pH 9.4, 4.3, 4.6), PAS, and Oil red O staining. Immunohistochemical study revealed strong immunostaining of TAs with antibodies against emerin and 7 SERCA2-ATPase. Immunostaining of TAs was also seen with antibodies against heat shock protein and dysferlin, but not with antibodies to lamin A, dystrophin, adhalin, beta, gamma, delta sarcoglycans, and merosin. These results suggest that emerin, an inner nuclear membrane protein, is present at the TAs. The interpretation and significance of this finding is discussed in relation to experimental data suggesting that normal emerin localization at the inner nuclear membrane depends on lamin A and mutations in the N-terminal domain of emerin cause mislocalization of the protein to the sarcoplasmic membranes.

  12. Tubular inverse opal scaffolds for biomimetic vessels.

    PubMed

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

    2016-07-14

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

  13. Tubular inverse opal scaffolds for biomimetic vessels.

    PubMed

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

    2016-07-14

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

  14. Study on durability for thermal cycle of planar SOFC

    SciTech Connect

    Ando, Motoo; Nakata, Kei-ichi; Wakayama, Sin-ichi

    1996-12-31

    TONEN CORPORATION has developed planar type SOFC since 1986. We demonstrated the output of 1.3 kW in 1991 and 5.1 kW in 1995. Simultaneously we have studied how to raise electric efficiency and reliability utilizing hydrogen and propane as fuel. Durability for thermal cycle is one of the most important problems of planar SOFC to make it more practical. The planar type SOFC is made up of separator, zirconia electrolyte and glass sealant. The thermal expansion of these components are expected to be the same value, however, they still possess small differences. In this situation, a thermal cycle causes a thermal stress due to the difference of the cell components and is often followed by a rupture in cell components, therefore, the analysis of the thermal stress should give us much useful information. The thermal cycle process consists of a heating up and cooling down procedure. Zirconia electrolyte is not bonded to the separator under the condition of the initial heating up procedure, and glass sealant becomes soft or melts and glass seals spaces between the zirconia and separator. The glass sealant becomes harder with the cooling down procedure. Moreover, zirconia is tightly bonded with separator below a temperature which is defined as a constraint temperature and thermal stress also occurs. This indicates that the heating up process relaxes the thermal stress and the cooling down increases it. In this paper, we simulated dependence of the stress on the sealing configuration, thermal expansion of sealant and constraint temperature of sealant glass. Furthermore, we presented SOFC electrical properties after a thermal cycle.

  15. Manufacture of SOFC electrodes by wet powder spraying

    SciTech Connect

    Wilkenhoener, R.; Mallener, W.; Buchkremer, H.P.

    1996-12-31

    The reproducible and commercial manufacturing of electrodes with enhanced electrochemical performance is of central importance for a successful technical realization of Solid Oxide Fuel Cell (SOFC) systems. The route of electrode fabrication for the SOFC by Wet Powder Spraying (WPS) is presented. Stabilized suspensions of the powder materials for the electrodes were sprayed onto a substrate by employing a spray gun. After drying of the layers, binder removal and sintering are performed in one step. The major advantage of this process is its applicability for a large variety of materials and its flexibility with regard to layer shape and thickness. Above all, flat or curved substrates of any size can be coated, thus opening up the possibility of {open_quotes}up-scaling{close_quotes} SOFC technology. Electrodes with an enhanced electrochemical performance were developed by gradually optimizing the different process steps. For example an optimized SOFC cathode of the composition La{sub 0.65}Sr{sub 0.3}MnO{sub 3} with 40% 8YSZ showed a mean overpotential of about -50 mV at a current density of -0.8 A/cm{sup 2}, with a standard deviation amounting to 16 mV (950{degrees}C, air). Such optimized electrodes can be manufactured with a high degree of reproducibility, as a result of employing a computer-controlled X-Y system for moving the spray gun. Several hundred sintered composites, comprising the substrate anode and the electrolyte, of 100x 100 mm{sup 2} were coated with the cathode by WPS and used for stack integration. The largest manufactured electrodes were 240x240 mm{sup 2}, and data concerning their thickness homogeneity and electrochemical performance are given.

  16. Innovative Seals for Solid Oxide Fuel Cells (SOFC)

    SciTech Connect

    Singh, Raj

    2008-06-30

    A functioning SOFC requires different type of seals such as metal-metal, metal-ceramic, and ceramic-ceramic. These seals must function at high temperatures between 600--900{sup o}C and in oxidizing and reducing environments of the fuels and air. Among the different type of seals, the metal-metal seals can be readily fabricated using metal joining, soldering, and brazing techniques. However, the metal-ceramic and ceramic-ceramic seals require significant research and development because the brittle nature of ceramics/glasses can lead to fracture and loss of seal integrity and functionality. Consequently, any seals involving ceramics/glasses require a significant attention and technology development for reliable SOFC operation. This final report is prepared to describe the progress made in the program on the needs, approaches, and performance of high temperature seals for SOFC. In particular, a new concept of self-healing glass seals is pursued for making seals between metal-ceramic material combinations, including some with a significant expansion mismatch.

  17. Fault Diagnosis Strategies for SOFC-Based Power Generation Plants

    PubMed Central

    Costamagna, Paola; De Giorgi, Andrea; Gotelli, Alberto; Magistri, Loredana; Moser, Gabriele; Sciaccaluga, Emanuele; Trucco, Andrea

    2016-01-01

    The success of distributed power generation by plants based on solid oxide fuel cells (SOFCs) is hindered by reliability problems that can be mitigated through an effective fault detection and isolation (FDI) system. However, the numerous operating conditions under which such plants can operate and the random size of the possible faults make identifying damaged plant components starting from the physical variables measured in the plant very difficult. In this context, we assess two classical FDI strategies (model-based with fault signature matrix and data-driven with statistical classification) and the combination of them. For this assessment, a quantitative model of the SOFC-based plant, which is able to simulate regular and faulty conditions, is used. Moreover, a hybrid approach based on the random forest (RF) classification method is introduced to address the discrimination of regular and faulty situations due to its practical advantages. Working with a common dataset, the FDI performances obtained using the aforementioned strategies, with different sets of monitored variables, are observed and compared. We conclude that the hybrid FDI strategy, realized by combining a model-based scheme with a statistical classifier, outperforms the other strategies. In addition, the inclusion of two physical variables that should be measured inside the SOFCs can significantly improve the FDI performance, despite the actual difficulty in performing such measurements. PMID:27556472

  18. Fault Diagnosis Strategies for SOFC-Based Power Generation Plants.

    PubMed

    Costamagna, Paola; De Giorgi, Andrea; Gotelli, Alberto; Magistri, Loredana; Moser, Gabriele; Sciaccaluga, Emanuele; Trucco, Andrea

    2016-08-22

    The success of distributed power generation by plants based on solid oxide fuel cells (SOFCs) is hindered by reliability problems that can be mitigated through an effective fault detection and isolation (FDI) system. However, the numerous operating conditions under which such plants can operate and the random size of the possible faults make identifying damaged plant components starting from the physical variables measured in the plant very difficult. In this context, we assess two classical FDI strategies (model-based with fault signature matrix and data-driven with statistical classification) and the combination of them. For this assessment, a quantitative model of the SOFC-based plant, which is able to simulate regular and faulty conditions, is used. Moreover, a hybrid approach based on the random forest (RF) classification method is introduced to address the discrimination of regular and faulty situations due to its practical advantages. Working with a common dataset, the FDI performances obtained using the aforementioned strategies, with different sets of monitored variables, are observed and compared. We conclude that the hybrid FDI strategy, realized by combining a model-based scheme with a statistical classifier, outperforms the other strategies. In addition, the inclusion of two physical variables that should be measured inside the SOFCs can significantly improve the FDI performance, despite the actual difficulty in performing such measurements.

  19. LG Solid Oxide Fuel Cell (SOFC) Model Development

    SciTech Connect

    Haberman, Ben; Martinez-Baca, Carlos; Rush, Greg

    2013-05-31

    This report presents a summary of the work performed by LG Fuel Cell Systems Inc. during the project LG Solid Oxide Fuel Cell (SOFC) Model Development (DOE Award Number: DE-FE0000773) which commenced on October 1, 2009 and was completed on March 31, 2013. The aim of this project is for LG Fuel Cell Systems Inc. (formerly known as Rolls-Royce Fuel Cell Systems (US) Inc.) (LGFCS) to develop a multi-physics solid oxide fuel cell (SOFC) computer code (MPC) for performance calculations of the LGFCS fuel cell structure to support fuel cell product design and development. A summary of the initial stages of the project is provided which describes the MPC requirements that were developed and the selection of a candidate code, STAR-CCM+ (CD-adapco). This is followed by a detailed description of the subsequent work program including code enhancement and model verification and validation activities. Details of the code enhancements that were implemented to facilitate MPC SOFC simulations are provided along with a description of the models that were built using the MPC and validated against experimental data. The modeling work described in this report represents a level of calculation detail that has not been previously available within LGFCS.

  20. Fault Diagnosis Strategies for SOFC-Based Power Generation Plants.

    PubMed

    Costamagna, Paola; De Giorgi, Andrea; Gotelli, Alberto; Magistri, Loredana; Moser, Gabriele; Sciaccaluga, Emanuele; Trucco, Andrea

    2016-01-01

    The success of distributed power generation by plants based on solid oxide fuel cells (SOFCs) is hindered by reliability problems that can be mitigated through an effective fault detection and isolation (FDI) system. However, the numerous operating conditions under which such plants can operate and the random size of the possible faults make identifying damaged plant components starting from the physical variables measured in the plant very difficult. In this context, we assess two classical FDI strategies (model-based with fault signature matrix and data-driven with statistical classification) and the combination of them. For this assessment, a quantitative model of the SOFC-based plant, which is able to simulate regular and faulty conditions, is used. Moreover, a hybrid approach based on the random forest (RF) classification method is introduced to address the discrimination of regular and faulty situations due to its practical advantages. Working with a common dataset, the FDI performances obtained using the aforementioned strategies, with different sets of monitored variables, are observed and compared. We conclude that the hybrid FDI strategy, realized by combining a model-based scheme with a statistical classifier, outperforms the other strategies. In addition, the inclusion of two physical variables that should be measured inside the SOFCs can significantly improve the FDI performance, despite the actual difficulty in performing such measurements. PMID:27556472

  1. Modeling and Performance of Anode-Supported SOFC

    SciTech Connect

    Chick, Lawrence A.; Stevenson, Jeffry W.; Meinhardt, Kerry D.; Simner, Steven P.; Jaffe, John E.; Williford, Rick E.

    2001-02-28

    A "one-dimensional", steady-state model of an SOFC stack was needed to support the design of balance-of-plant components for a 5 kW mobile SOFC system. This "stack module" was required to predict appropriate stack voltage responses to changes in fuel composition, fuel flow rate, stack temperature and current demand, with response characteristics that were adjustable to changes in stack component materials and dimensions as well as to electrode porosity. The spreadsheet-based stack module was derived from the work by Kim, Virkar et al (see J. Electrochem. Soc. 146(1) 69-78 (1999)), with modifications suggested by Riess and Schoonman, p291 in CRC Handbook of Electrochemistry (1997) CRC Press. The usual overpotential terms account for ohmic resistance of the cell components, losses due to charge transfer at the electrodes, and losses due to diffusion of reactants into and products out of the porous electrodes. Response of the module is compared to published cell and stack data. After fitting adjustable parameters to match particular cell performance characteristics, the module responds reasonably well to changes in temperature and fuel concentration. The module is used to analyze the performance of anode-supported cells that were fabricated at PNNL (see abstract submitted by Stevenson, Meinhardt, Simner, Habeger and Canfield, "Fabrication and Testing of Anode-Supported SOFC").

  2. Realisation of an anode supported planar SOFC system

    SciTech Connect

    Buchkremer, H.P.; Stoever, D.; Diekmann, U.

    1996-12-31

    Lowering the operating temperature of S0FCs to below 800{degrees}C potentially lowers production costs of a SOFC system because of a less expensive periphery and is able to guarantee sufficient life time of the stack. One way of achieving lower operating temperatures is the development of new high conductive electrolyte materials. The other way, still based on state-of-the-art material, i.e. yttria-stabilized zirconia (YSZ) electrolyte, is the development of a thin film electrolyte concept. In the Forschungszentrum Julich a program was started to produce a supported planar SOFC with an YSZ electrolyte thickness between 10 to 20 put. One of the electrodes, i.e. the anode, was used as support, in order not to increase the number of components in the SOFC. The high electronic conductivity of the anode-cermet allows the use of relatively thick layers without increasing the cell resistance. An additional advantage of the supported planar concept is the possibility to produce single cells larger than 10 x 10 cm x cm, that is with an effective electrode cross area of several hundred cm{sup 2}.

  3. 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.

  4. 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.

  5. An open tubular ion chromatograph.

    PubMed

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

    2014-12-01

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

  6. 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...

  7. Fabrication and characterization of anode-supported micro-tubular solide oxide fuel cell by phase inversion method

    NASA Astrophysics Data System (ADS)

    Ren, Cong

    Nowadays, the micro-tubular solid oxide fuel cells (MT-SOFCs), especially the anode supported MT-SOFCs have been extensively developed to be applied for SOFC stacks designation, which can be potentially used for portable power sources and vehicle power supply. To prepare MT-SOFCs with high electrochemical performance, one of the main strategies is to optimize the microstructure of the anode support. Recently, a novel phase inversion method has been applied to prepare the anode support with a unique asymmetrical microstructure, which can improve the electrochemical performance of the MT-SOFCs. Since several process parameters of the phase inversion method can influence the pore formation mechanism and final microstructure, it is essential and necessary to systematically investigate the relationship between phase inversion process parameters and final microstructure of the anode supports. The objective of this study is aiming at correlating the process parameters and microstructure and further preparing MT-SOFCs with enhanced electrochemical performance. Non-solvent, which is used to trigger the phase separation process, can significantly influence the microstructure of the anode support fabricated by phase inversion method. To investigate the mechanism of non-solvent affecting the microstructure, water and ethanol/water mixture were selected for the NiO-YSZ anode supports fabrication. The presence of ethanol in non-solvent can inhibit the growth of the finger-like pores in the tubes. With the increasing of the ethanol concentration in the non-solvent, a relatively dense layer can be observed both in the outside and inside of the tubes. The mechanism of pores growth and morphology obtained by using non-solvent with high concentration ethanol was explained based on the inter-diffusivity between solvent and non-solvent. Solvent and non-solvent pair with larger Dm value is benefit for the growth of finger-like pores. Three cells with different anode geometries was

  8. High-efficiency, nickel-ceramic composite anode current collector for micro-tubular solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Li, Tao; Wu, Zhentao; Li, K.

    2015-04-01

    High manufacturing cost and low-efficient current collection have been the two major bottlenecks that prevent micro-tubular SOFCs from large-scale application. In this work, a new nickel-based composite anode current collector has been developed for anode-supported MT-SOFC, addressing reduced cost, manufacturability and current collection efficiencies. Triple-layer hollow fibers have been successfully fabricated via a phase inversion-assisted co-extrusion process, during which a thin nickel-based inner layer was uniformly coated throughout the interior anode surface for improved adhesion with superior process economy. 10 wt.% CGO was added into the inner layer to prevent the excessive shrinkage of pure NiO, thus helping to achieve the co-sintering process. The electrochemical performance tests illustrate that samples with the thinnest anodic current collector (15% of the anode thickness) displayed the highest power density (1.07 W cm-2). The impedance analysis and theoretical calculations suggest that inserting the anodic current collector could dramatically reduce the percentage of contact loss down to 6-10 % of the total ohmic loss (compared to 70% as reported in literatures), which proves the high efficiencies of new current collector design. Moreover, the superior manufacturability and process economy suggest this composite current collector suitable for mass-scale production.

  9. Porous Yttria-Stabilized Zirconia Microstructures for SOFC Anode Fabrication

    NASA Astrophysics Data System (ADS)

    Palakkathodi Kammampata, Sanoop

    Solid oxide fuel cells (SOFCs) are electrochemical devices that convert fuels, such as hydrogen and natural gas, to electricity at high efficiencies, e.g., up to 90 %. SOFCs are emerging as a key technology for energy production that also minimize greenhouse gas emissions compared to conventional thermal power generation. SOFCs, which are normally based on nickel-yttria stabilized zirconia (YSZ) anodes, undergo degradation with time due to their high operating temperatures and their susceptibility to damage due to anode oxidation (redox cycling) and poisoning. Ni infiltration into porous YSZ scaffolds is considered to be a promising approach for overcoming some of these problems and enhancing their redox tolerance. However, long-term instability of the morphology of these types of anodes is an important problem. The focus of this thesis was therefore to develop methods to form porous YSZ scaffolds and attempt to construct stable Ni-YSZ anodes with reasonable electrochemical performance by infiltration. In this work, the issue of long-term instability was considered to originate from both the porous YSZ scaffold microstructure and the Ni infiltration precursor employed. To study this more closely, two different porous YSZ scaffold microstructures were developed by using tape casting, followed by Ni infiltration using a polymeric precursor, known to form a continuous Ni phase, rather than electrically separated Ni particles. Ni infiltration into porous YSZ scaffolds with large grains (0.5 microm) and large pores (two types of pores: ˜0.5 microm and 5 microm) resulted in extensive Ni particle growth that resulted in poor stability and poor electrochemical performance (0.5 Ω cm2 per electrode at 800°C). Ni infiltration into a scaffold having finer grains and pores (˜200 nm each) resulted in anodes with a much lower polarization resistance of 0.11 Ω cm2 per electrode at 800°C, increasing by ˜5 % after 108 hours at this temperature.

  10. Energy recuperation in solid oxide fuel cell (SOFC) and gas turbine (GT) combined system

    NASA Astrophysics Data System (ADS)

    Kuchonthara, Prapan; Bhattacharya, Sankar; Tsutsumi, Atsushi

    A combined power generation system consisting of a solid oxide fuel cell (SOFC) and a gas turbine (GT) with steam and heat recuperation (HR) was evaluated using a commercial process simulation tool, ASPEN Plus. The effect of steam recuperation (SR) on the overall efficiency of the combined system was investigated by comparing the SOFC-GT during heat and steam recuperation (HSR) against the system during only heat recuperation. At low turbine inlet temperatures (TITs), the overall efficiency of the SOFC-GT combined system with heat and steam recuperation improved by showing an increase in TIT and a reduction in pressure ratio (PR). On the other hand, at high TITs, the opposite trend was observed. The integration of steam recuperation was found to improve the overall efficiency and specific power of SOFC-GT combined systems with a relatively compact SOFC component.

  11. Manganese-doped lanthanum calcium titanate as an interconnect for flat-tubular solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Raeis Hosseini, Niloufar; Sammes, Nigel Mark; Chung, Jong Shik

    2014-01-01

    A cost-effective screen-printing process is developed to fabricate a dense layer of solid oxide fuel cell (SOFC) interconnect material. A series of lanthanum-manganese-doped CaTiO3 perovskite oxides (La0.4Ca0.6Ti1-xMnxO3-δ; (x = 0.0, 0.2, 0.4, 0.6)) powders is successfully synthesized using an EDTA-citrate method and co-sintered as an interconnect material on an extruded porous anode substrate in a flat-tubular solid oxide fuel cell. All samples adopt a single perovskite phase after calcination at 950 °C for 5 h. High-temperature XRD confirms that the perovskite structure is thermally stable in both oxidizing and reducing conditions. The highest electrical conductivity occurs when x = 0.6; at 12.20 S cm-1 and 2.70 S cm-1 under oxidizing and reducing conditions. The thermal expansion coefficient of La0.4Ca0.6Ti0.4Mn0.6O3 is 10.76 × 10-6 K-1, which closely matches that of 8 mol% yttria-stabilized zirconia. Chemical compatibility of samples and their reduction stability are verified at the operating temperature. The power density and area-specific resistance value at x = 0.6 is 208 mW cm-1 and 1.23 Ω cm2 at 800 °C under open circuit voltage, and 200 mV signal amplitude under 3% humidified hydrogen and air respectively. This performance indicates that La0.4Ca0.6Ti0.4Mn0.6O3-δ has potential for use as interconnect in a flat tubular SOFC.

  12. SOFC chromite sintering and electrolyte/air-electrode interface reactions

    SciTech Connect

    Bates, J.L.; Chick, L.A.; Youngblood, G.E.

    1992-04-01

    Air sintering of chromites was investigated in La(Sr)CrO[sub 3], La(Ca)CrO[sub 3], and Y(Ca)CrO[sub 3]. Effects of alkaline earth dopant level and chromium enrichment/depletion on chromite sintered densities and microstructures are discussed. Ac impedance spectroscopy and dc polarization coupled with an unbonded interface cell were used to examine SOFC (solid oxide fuel cells) electrochemical reactions at solid-solid-gas interfaces, particularly for La[sub 1-x]Sr[sub x]MnO[sub 3]. 5 refs.

  13. SOFC chromite sintering and electrolyte/air-electrode interface reactions

    SciTech Connect

    Bates, J.L.; Chick, L.A.; Youngblood, G.E.

    1992-04-01

    Air sintering of chromites was investigated in La(Sr)CrO{sub 3}, La(Ca)CrO{sub 3}, and Y(Ca)CrO{sub 3}. Effects of alkaline earth dopant level and chromium enrichment/depletion on chromite sintered densities and microstructures are discussed. Ac impedance spectroscopy and dc polarization coupled with an unbonded interface cell were used to examine SOFC (solid oxide fuel cells) electrochemical reactions at solid-solid-gas interfaces, particularly for La{sub 1-x}Sr{sub x}MnO{sub 3}. 5 refs.

  14. 10 kW SOFC Power System Commercialization

    SciTech Connect

    Dan Norrick; Brad Palmer; Charles Vesely; Eric Barringer; John Budge; Cris DeBellis; Rich Goettler; Milind Kantak; Steve Kung; Zhien Liu; Tom Morris; Keith Rackers; Gary Roman; Greg Rush; Liang Xue

    2006-02-01

    Cummins Power Generation (CPG) as the prime contractor and SOFCo-EFS Holdings LLC (SOFCo), as their subcontractor, teamed under the Solid-state Energy Conversion Alliance (SECA) program to develop 3-10kW solid oxide fuel cell systems for use in recreational vehicles, commercial work trucks and stand-by telecommunications applications. The program goal is demonstration of power systems that meet commercial performance requirements and can be produced in volume at a cost of $400/kW. This report summarizes the team's activities during the seventh six-month period (July-December 2005) of the four-year Phase I effort. While there has been significant progress in the development of the SOFC subsystems that can support meeting the program Phase 1 goals, the SOFCo ceramic stack technology has progressed significantly slower than plan and CPG consider it unlikely that the systemic problems encountered will be overcome in the near term. SOFCo has struggled with a series of problems associated with inconsistent manufacturing, inadequate cell performance, and the achievement of consistent, durable, low resistance inter-cell connections with reduced or no precious materials. A myriad of factors have contributed to these problems, but the fact remains that progress has not kept pace with the SECA program. A contributing factor in SOFCo's technical difficulties is attributed to their significantly below plan industry cost share spending over the last four years. This has resulted in a much smaller SOFC stack development program, has contributed to SOFCo not being able to aggressively resolve core issues, and clouds their ability to continue into a commercialization phase. In view of this situation, CPG has conducted an independent assessment of the state-of-the-art in planar SOFC's stacks and have concluded that alternative technology exists offering the specific performance, durability, and low cost needed to meet the SECA objectives. We have further concluded that there is

  15. Progress in the planar CPn SOFC system design verification

    SciTech Connect

    Elangovan, S.; Hartvigsen, J.; Khandkar, A.

    1996-04-01

    SOFCo is developing a high efficiency, modular and scaleable planar SOFC module termed the CPn design. This design has been verified in a 1.4 kW module test operated directly on pipeline natural gas. The design features multistage oxidation of fuel wherein the fuel is consumed incrementally over several stages. High efficiency is achieved by uniform current density distribution per stage, which lowers the stack resistance. Additional benefits include thermal regulation and compactness. Test results from stack modules operating in pipeline natural gas are presented.

  16. Overview of SOFC Anode Interactions with Coal Gas Impurities

    SciTech Connect

    O. A. Marina; L. R. Pederson; R. Gemmen; K. Gerdes; H. Finklea; I. B. Celik

    2010-03-01

    An overview of the results of SOFC anode interactions with phosphorus, arsenic, selenium, sulfur, antimony, and hydrogen chloride as single contaminants or in combinations is discussed. Tests were performed using both anode- and electrolyte-supported cells in synthetic and actual coal gas for periods greater than 1000 hours. Post-test analyses were performed to identify reaction products formed and their distribution, and compared to phases expected from thermochemical modeling. The ultimate purpose of this work is to establish maximum permissible concentrations for impurities in coal gas, to aid in the selection of appropriate coal gas clean-up technologies.

  17. Overview of SOFC Anode Interactions with Coal Gas Impurities

    SciTech Connect

    Marina, Olga A.; Pederson, Larry R.; Gemmen, Randall; Gerdes, Kirk; Finklea, Harry; Celik, Ismail B.

    2010-05-01

    An overview of the results of SOFC anode interactions with phosphorus, arsenic, selenium, sulfur, antimony, and hydrogen chloride as single contaminants or in combinations is discussed. Tests were performed using both anode- and electrolyte-supported cells in synthetic and actual coal gas for periods greater than 1000 hours. Post-test analyses were performed to identify reaction products formed and their distribution, and compared to phases expected from thermochemical modeling. The ultimate purpose of this work is to establish maximum permissible concentrations for impurities in coal gas, to aid in the selection of appropriate coal gas clean-up technologies.

  18. Development of self-supporting air electrode SOFC

    SciTech Connect

    Nagata, M.; Iwasawa, C.; Yamaoka, S.; Seino, Y.; Ono, M.

    1995-12-31

    The authors are studying a self-supporting SOFC using the spray coating method, etc. A high-performance self-supporting air electrode has successfully been produced by the extrusion-sintering method, and a cell with its electrolyte and fuel electrode manufactured by the plasma spray coating method on the air electrode proved to have good performance. The maximum output density of a single cell is 0.31W/cm{sup 2}. Furthermore, the authors are developing a FGM (Functionally Gradient Material) film as the fuel electrode produced by the plasma spray coating method.

  19. Improvement of SOFC electrodes using mixed ionic-electronic conductors

    SciTech Connect

    Matsuzaki, Y.; Hishinuma, M.

    1996-12-31

    Since the electrode reaction of SOFC is limited to the proximity of a triple phase boundary (TPB), the local current density at the electrode and electrolyte interface is larger than mean current density, which causes large ohmic and electrode polarization. This paper describes an application of mixed ionic-electronic conductors to reduce such polarization by means of (1) enhancing ionic conductivity of the electrolyte surface layer by coating a high ionic conductors, and (2) reducing the local current density by increasing the electrochemically active sites.

  20. Salicylate-induced proximal tubular dysfunction.

    PubMed

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

    2007-09-01

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

  1. Computer simulation and experimental characterization of a tubular micro-solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Amiri, Mohammad Saeid

    This work is focused on a state-of-the-art tubular micro-solid oxide fuel cell (TmuSOFC), ˜3 millimeters in diameter and ˜300 microns thick, with Ni/YSZ and LSM/YSZ composite electrodes and a YSZ electrolyte. A 2D axi-symmetric, multi-scale CFD model is developed which includes the fluid flow, mass transfer, and heat transfer within the gas channels and the porous electrodes. The electrochemical reactions are modeled within the volume of the electrodes, enabling the model to account for the extent of the reaction zone. Thermodynamic expressions are developed to estimate the single-electrode reversible heat generation and the single-electrode electromotive force of a non-isothermal electrochemical cell. The isothermal, non-isothermal, and transient models are each validated against the experimental results, and consistent with the physical reality of the TmuSOFC. A novel approach is used to estimate the kinetic parameters, enabling the simulations to be used as a diagnostic tool. The model is used to gain a thorough insight about the TmuSOFC. The cathode electrochemical activity and the anode support ohmic loss are identified as the two major performance bottlenecks for this cell. Including radiation is found to be essential for a physically meaningful heat transfer model. The thermoelectric effects on the cell overall electromotive force is found to be negligible. It is found that the anode reaction is always endothermic, while the cathode reaction is always exothermic, and that the temperature gradients across the cell layers are less than 0.05°C. The cell transient response is found to be fast, and dominated by the thermal transients. Several physical properties used in the model are measured experimentally, indicating that that the correlations used in the literature are not always suitable, especially when new fabrication techniques are used. The conductivity of the anode support was measured to be several orders of magnitude lower than expected and very

  2. Liquid-fueled SOFC power sources for transportation

    NASA Astrophysics Data System (ADS)

    Myles, K. M.; Doshi, R.; Kumar, R.; Krumpelt, M.

    Traditionally, fuel cells have been developed for space or stationary terrestrial applications. As the first commercial 200-kW systems were being introduced by ONSI and Fuji Electric, the potentially much larger, but also more challenging, application in transportation was beginning to be addressed. As a result, fuel cell-powered buses have been designed and built, and R&D programs for fuel cell-powered passenger cars have been initiated. The engineering challenge of eventually replacing the internal combustion engine in buses, trucks, and passenger cars with fuel cell systems is to achieve much higher power densities and much lower costs than obtainable in systems designed for stationary applications. At present, the leading fuel cell candidate for transportation applications is, without question, the polymer electrolyte fuel cell (PEFC). Offering ambient temperature start-up and the potential for a relatively high power density, the polymer technology has attracted the interest of automotive manufacturers worldwide. But the difficulties of fuel handling for the PEFC have led to a growing interest in exploring the prospects for solid oxide fuel cells (SOFCs) operating on liquid fuels for transportation applications. Solid oxide fuel cells are much more compatible with liquid fuels (methanol or other hydrocarbons) and are potentially capable of power densities high enough for vehicular use. Two SOFC options for such use are discussed in this report.

  3. Liquid-fueled SOFC power sources for transportation

    SciTech Connect

    Myles, K.M.; Doshi, R.; Kumar, R.; Krumpelt, M.

    1994-11-01

    Traditionally, fuel cells have been developed for space or stationary terrestrial applications. As the first commercial 200-kW systems were being introduced by ONSI and Fuji Electric, the potentially much larger, but also more challenging, application in transportation was beginning to be addressed. As a result, fuel cell-powered buses have been designed and built, and R&D programs for fuel cell-powered passenger cars have been initiated. The engineering challenge of eventually replacing the internal combustion engine in buses, trucks, and passenger cars with fuel cell systems is to achieve much higher power densities and much lower costs than obtainable in systems designed for stationary applications. At present, the leading fuel cell candidate for transportation applications is, without question, the polymer electrolyte fuel cell (PEFC). Offering ambient temperature start-up and the potential for a relatively high power density, the polymer technology has attracted the interest of automotive manufacturers worldwide. But the difficulties of fuel handling for the PEFC have led to a growing interest in exploring the prospects for solid oxide fuel cells (SOFCs) operating on liquid fuels for transportation applications. Solid oxide fuel cells are much more compatible with liquid fuels (methanol or other hydrocarbons) and are potentially capable of power densities high enough for vehicular use. Two SOFC options for such use are discussed in this report.

  4. Overview of SOFC Anode Interactions with Coal Gas Impurities

    SciTech Connect

    Marina, Olga A.; Pederson, Larry R.; Gemmen, Randall; Gerdes, Kirk; Finklea, Harry; Celik, Ismail B.

    2009-08-11

    Efficiencies greater than 50 percent (higher heating value) have been projected for solid oxide fuel cell (SOFC) systems fueled with gasified coal, even with carbon sequestration. Multiple minor and trace components are present in coal that could affect fuel cell performance, however, which vary widely depending on coal origin and type. Minor and trace components have been classified into three groups: elements with low volatility that are likely to remain in the ash, elements that will partition between solid and gas phases, and highly volatile elements that are unlikely to condense. Those in the second group are of most concern. In the following, an overview of the results of SOFC anode interactions with phosphorus, arsenic, selenium, sulfur, antimony, and hydrogen chloride as single contaminants or in combinations is discussed. Tests were performed using both anode- and electrolyte-supported cells in synthetic coal gas. The ultimate purpose of this work is to establish maximum permissible concentrations for impurities in coal gas, to aid in the selection of appropriate coal gas clean-up technologies.

  5. Tubular solid oxide fuel cell demonstration activities

    SciTech Connect

    Ray, E.R.; Veyo, S.E.

    1995-12-31

    This reports on a solid oxide fuel cell demonstration program in which utilities are provided fully integrated, automatically controlled, packaged solid oxide fuel cell power generation systems. These field units serve to demonstrate to customers first hand the beneficial attributes of the SOFC, to expose deficiencies through experience in order to guide continued development, and to garner real world feedback and data concerning not only cell and stack parameters, but also transportation, installation, permitting and licensing, start-up and shutdown, system alarming, fault detection, fault response, and operator interaction.

  6. 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.

  7. Tubular membrane bioreactors for biotechnological processes.

    PubMed

    Wolff, Christoph; Beutel, Sascha; Scheper, Thomas

    2013-02-01

    This article is an overview of bioreactors using tubular membranes such as hollow fibers or ceramic capillaries for cultivation processes. This diverse group of bioreactor is described here in regard to the membrane materials used, operational modes, and configurations. The typical advantages of this kind of system such as environments with low shear stress together with high cell densities and also disadvantages like poor oxygen supply are summed up. As the usage of tubular membrane bioreactors is not restricted to a certain organism, a brief overview of various applications covering nearly all types of cells from prokaryotic to eukaryotic cells is also given here. PMID:23224587

  8. Dense Membranes for Anode Supported all Perovskite IT-SOFCs

    SciTech Connect

    Rambabu Bobba

    2006-09-14

    During this first year of the project, a post doctoral fellow (Dr. Hrudananda Jena), and two graduate students (Mr. Vinay B. V. Sivareddy, Aswin Somuru), were supported through this project funds. Also, partial support was provided to three undergraduate students (Jonthan Dooley, India Snowden, Jeremy Gilmore) majoring in Chemistry, Physics, and Engineering disciplines. Various wet chemical methods of synthesis have been attempted to prepare perovskite oxide powders with a hope to improve and engineer its properties to meet the requirements of Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFCs) components. Various compounds were synthesized, characterized by XRD, TEM, SEM, XPS, electron microprobe and their electrical transport properties were measured by EIS at elevated temperatures and compared. Sonochemical technique (power of ultra sonic probe 750 watt) combined with hydrothermal treatment of precursors for the preparation of calcium hydroxy apatites (Ca-HAp) was used for the first time. Ca-HAp was substituted with Sr and Mg (50% replacement of Ca in Ca-HAp) to study the effect of substitution on Ca-HAp. Calcium hydroxy apatite is a bioceramic and has potential applications as artificial bone, enamel materials. In this study we tried to investigate its use as proton conductors in PC-SOFC. The properties like electrical conductivity, crystal structure, compositions of CaHAp were studied and compared with the natural bone material. The comparison found to be excellent indicating the efficiency of the preparation techniques. The typical value of conductivity measured is 0.091 x 10{sup -6} Scm{sup -1} at 25 C and 19.26 x 10{sup -6} Scm{sup -1} at 850 C with an applied frequency of 100 kHz. The conductivity increases on increasing frequency and temperature and reaches 0.05mS/cm at 500 C. The crystal structure and phase stability of perovskites as well as apatites were investigated with respect to substitution of various iso-valent and alivalent ions to

  9. Cytomorphology of tubular adenoma breast--a case report.

    PubMed

    Ravindra, Savithri; Suguna, B V

    2006-04-01

    Tubular adenoma a 'pure adenoma' is a benign neoplasm of breast presenting clinically like fibroadenoma. We report cytological and histological features of tubular adenoma in a 24 year old female with brief review of literature.

  10. Physically based dynamic modeling of planar anode-supported sofc cogeneration systems

    NASA Astrophysics Data System (ADS)

    Albrecht, Kevin J.

    Abstract Solid oxide fuel cells (SOFC) have been a key area of academic research interest over the past decade due to their high electrical efficiency, fuel flexibility, and high quality waste heat. These benefits suggest that SOFCs could play a significant role as a future distributed generation, combined heat and power source if life cycle cost can be reduced or significant incentives such as a carbon tax are implemented. At the current point in SOFC development, degradation effects limit the operational lifetime of SOFCs. Other research efforts have suggested that the dynamic operation of SOFCs could improve the economics in addition to reducing degradation. Thus the development of high fidelity modeling tools for the assessment of dynamic SOFC system operation is important to determine the potential load-following ability of SOFC systems. One of the goals of this research is to identify the required level of fidelity necessary for a dynamic SOFC system-level simulation tool. The channel-level steady-state simulation and dynamic response to step changes in current density are presented for a one-dimensional and `quasi' two-dimensional model. The results indicate the predicted temperature gradient is less severe when implementing a higher fidelity `quasi' two-dimensional model. Additionally, the modeling and sizing of the balance of plant components to simulate off-design and system dynamics are presented. The effects of dynamic balance of plant components are compared to the typically accepted steady-state models. The incorporation of the dynamic balance of plant components are shown to have a significant effect on the dynamics of the waste heat recovery, where the power dynamics are only minimally affected. Finally, the steady-state performance at off-design conditions and dynamic response to step changes in the net system power are presented to assess the potential load-following ability of a combined heat and power SOFC system.

  11. Drill pipes and casings utilizing multi-conduit tubulars

    SciTech Connect

    Curlett, H.B.

    1989-01-24

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

  12. 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.

  13. Boron--epoxy tubular structure members

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  14. Novel Composite Materials for SOFC Cathode-Interconnect Contact

    SciTech Connect

    J. H. Zhu

    2009-07-31

    This report summarized the research efforts and major conclusions of our University Coal Research Project, which focused on developing a new class of electrically-conductive, Cr-blocking, damage-tolerant Ag-perovksite composite materials for the cathode-interconnect contact of intermediate-temperature solid oxide fuel cell (SOFC) stacks. The Ag evaporation rate increased linearly with air flow rate initially and became constant for the air flow rate {ge} {approx} 1.0 cm {center_dot} s{sup -1}. An activation energy of 280 KJ.mol{sup -1} was obtained for Ag evaporation in both air and Ar+5%H{sub 2}+3%H{sub 2}O. The exposure environment had no measurable influence on the Ag evaporation rate as well as its dependence on the gas flow rate, while different surface morphological features were developed after thermal exposure in the oxidizing and reducing environments. Pure Ag is too volatile at the SOFC operating temperature and its evaporation rate needs to be reduced to facilitate its application as the cathode-interconnect contact. Based on extensive evaporation testing, it was found that none of the alloying additions reduced the evaporation rate of Ag over the long-term exposure, except the noble metals Au, Pt, and Pd; however, these noble elements are too expensive to justify their practical use in contact materials. Furthermore, the addition of La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSM) into Ag to form a composite material also did not significantly modify the Ag evaporation rate. The Ag-perovskite composites with the perovskite being either (La{sub 0.6}Sr{sub 0.4})(Co{sub 0.8}Fe{sub 0.2})O{sub 3} (LSCF) or LSM were systematically evaluated as the contact material between the ferritic interconnect alloy Crofer 22 APU and the LSM cathode. The area specific resistances (ASRs) of the test specimens were shown to be highly dependent on the volume percentage and the type of the perovskite present in the composite contact material as well as the amount of thermal cycling

  15. FEASIBILITY OF A STACK INTEGRATED SOFC OPTICAL CHEMICAL SENSOR

    SciTech Connect

    Michael A. Carpenter

    2004-03-30

    The work performed during the UCR Innovative Concepts phase I program was designed to demonstrate the chemical sensing capabilities of nano-cermet SPR bands at solid oxide fuel cell operating conditions. Key to this proposal is that the materials choice used a YSZ ceramic matrix which upon successful demonstration of this concept, will allow integration directly onto the SOFC stack. Under the Innovative Concepts Program the University at Albany Institute for Materials (UAIM)/UAlbany School of NanoSciences and NanoEngineering synthesized, analyzed and tested Pa, and Au doped YSZ nano-cermets as a function of operating temperature and target gas exposure (hydrogen, carbon monoxide and 1-dodecanethiol). During the aforementioned testing procedure the optical characteristics of the nano-cermets were monitored to determine the sensor selectivity and sensitivity.

  16. Fabrication and characteristics of unit cell for SOFC

    SciTech Connect

    Kim, Gwi-Yeol; Eom, Seung-Wook; Moon, Seong-In

    1996-12-31

    Research and development on solid oxide fuel cells in Korea have been mainly focused on unit cell and small stack. Fuel cell system is called clean generation system which not cause NOx or SOx. It is generation efficiency come to 50-60% in contrast to 40% of combustion generation system. Among the fuel cell system, solid oxide fuel cell is constructed of ceramics, so stack construction is simple, power density is very high, and there are no corrosion problems. The object of this study is to develop various composing material for SOFC generation system, and to test unit cell performance manufactured. So we try to present a guidance for developing mass power generation system. We concentrated on development of manufacturing process for cathode, anode and electrolyte.

  17. 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...

  18. Tubular solid oxide fuel cell demonstration activities

    SciTech Connect

    Veyo, S.E.

    1995-08-01

    The development of a viable fuel cell driven electrical power generation system involves not only the development of cell and stack technology, but also the development of the overall system concept, the strategy for control, and the ancillary subsystems. The design requirements used to guide system development must reflect a customer focus in order to evolve a commercial product. In order to obtain useful customer feedback, Westinghouse has practiced the deployment with customers of fully integrated, automatically controlled, packaged solid oxide fuel cell power generation systems. These field units have served to demonstrate to customers first hand the beneficial attributes of the SOFC, to expose deficiencies through experience in order to guide continued development, and to garner real world feedback and data concerning not only cell and stack parameters, but also transportation, installation, permitting and licensing, start-up and shutdown, system alarming, fault detection, fault response, and operator interaction.

  19. 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.

  20. 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.

  1. 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.

  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. Pointlike Inclusion Interactions in Tubular Membranes

    NASA Astrophysics Data System (ADS)

    Vahid, Afshin; Idema, Timon

    2016-09-01

    Membrane tubes and tubular networks are ubiquitous in living cells. Inclusions like proteins are vital for both the stability and the dynamics of such networks. These inclusions interact via the curvature deformations they impose on the membrane. We analytically study the resulting membrane mediated interactions in strongly curved tubular membranes. We model inclusions as constraints coupled to the curvature tensor of the membrane tube. First, as special test cases, we analyze the interaction between ring- and rod-shaped inclusions. Using Monte Carlo simulations, we further show how pointlike inclusions interact to form linear aggregates. To minimize the curvature energy of the membrane, inclusions self-assemble into either line- or ringlike patterns. Our results show that the global curvature of the membrane strongly affects the interactions between proteins embedded in it, and can lead to the spontaneous formation of biologically relevant structures.

  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. Molecular Pathophysiology of Renal Tubular Acidosis

    PubMed Central

    Pereira, P.C.B; Miranda, D.M; Oliveira, E.A; Silva, A.C. Simões e

    2009-01-01

    Renal tubular acidosis (RTA) is characterized by metabolic acidosis due to renal impaired acid excretion. Hyperchloremic acidosis with normal anion gap and normal or minimally affected glomerular filtration rate defines this disorder. RTA can also present with hypokalemia, medullary nephrocalcinosis and nephrolitiasis, as well as growth retardation and rickets in children, or short stature and osteomalacia in adults. In the past decade, remarkable progress has been made in our understanding of the molecular pathogenesis of RTA and the fundamental molecular physiology of renal tubular transport processes. This review summarizes hereditary diseases caused by mutations in genes encoding transporter or channel proteins operating along the renal tubule. Review of the molecular basis of hereditary tubulopathies reveals various loss-of-function or gain-of-function mutations in genes encoding cotransporter, exchanger, or channel proteins, which are located in the luminal, basolateral, or endosomal membranes of the tubular cell or in paracellular tight junctions. These gene mutations result in a variety of functional defects in transporter/channel proteins, including decreased activity, impaired gating, defective trafficking, impaired endocytosis and degradation, or defective assembly of channel subunits. Further molecular studies of inherited tubular transport disorders may shed more light on the molecular pathophysiology of these diseases and may significantly improve our understanding of the mechanisms underlying renal salt homeostasis, urinary mineral excretion, and blood pressure regulation in health and disease. The identification of the molecular defects in inherited tubulopathies may provide a basis for future design of targeted therapeutic interventions and, possibly, strategies for gene therapy of these complex disorders. PMID:19721811

  6. Latch ring for connecting tubular member

    SciTech Connect

    Milberger, L.J.

    1991-06-04

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

  7. 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)

  8. ANODE, CATHODE AND THIN FILM STUDIES FOR LOW TEMPERATURE SOFC'S

    SciTech Connect

    Dr. Wayne Huebner; Dr. Harlan U. Anderson

    1999-11-01

    In this research the microstructure {leftrightarrow} property relations in solid oxide fuel cells (SOFC's) are being studied to better understand the mechanisms involved in cell performance. The overall aim is to fabricate SOFC's with controlled, stable, high performance microstructure. Most cathode studies were completed in the last DOE contract; studies during this year focused more on the influence of nonstoichiometry on the electrical performance. Studies indicate that nonstoichiometric La{sub x}Sr{sub 0.20}MnO{sub 3}(x = 0.70, 0.75, and 0.79) cathode compositions exhibit the best properties. A series of studies using these compositions fired on at temperatures of 1100, 1200, 1300 and 1400 C were performed. In all instances, 1200 C was the optimum, with the x = 0.70 composition being the best. It has an overpotential of only 0.04V at 1 A/cm{sup 2}. SEM analyses indicated no second phases or interdiffusion is detectable. Studies on optimization of anode compositions yielded the optimum volume fraction of Ni (45vol%), the best sintering temperature/time (1400 C/2 h), and the best starting materials (glycine-nitrate derived NiO and normal YSZ). In essence these results simply reflect the optimum microstructure. As such, they are being used to guide the development of optimized anodes for lower temperature operation based on Cu/CeO{sub 2} cermets. Marked success has been achieved on the placement of thin YSZ electrolytes on porous Ni/YSZ electrodes. The process being used is a transfer technique in which dense YSZ films are initially fabricated on NaCl or polymeric substrates, followed by partial dissolution of the substrate and placement of the film on the porous substrate. This technique has allowed us to produce structures with film thicknesses ranging from 70 to 3000 nm, and grain sizes ranging from 2 to 300 nm. Cells based on electrolytes this thick should operate in the 400--700 C range.

  9. Measurement of residual stresses in deposited films of SOFC component materials

    SciTech Connect

    Kato, T.; Momma, A.; Nagata, S.; Kasuga, Y.

    1996-12-31

    The stress induced in Solid oxide fuel cells (SOFC)s has important influence on the lifetime of SOFC. But the data on stress in SOFC and mechanical properties of SOW component materials have not been accumulated enough to manufacture SOFC. Especially, the data of La{sub 1-x}Sr{sub x}MnO{sub 3} cathode and La{sub 1-x}Sr{sub x}CrO{sub 3} interconnection have been extremely limited. We have estimated numerically the dependences of residual stress in SOFC on the material properties, the cell structure and the fabrication temperatures of the components, but these unknown factors have caused obstruction to simulate the accurate behavior of residual stress. Therefore, the residual stresses in deposited La{sub 1-x}Sr{sub x}MnO{sub 3} and La{sub 1-x}Sr{sub x}CrO{sub 3} films are researched by the observation of the bending behavior of the substrate strips. The films of SOFC component materials were prepared by the RF sputtering method, because: (1) It can fabricate dense films of poor sinterable material such as La{sub 1-x}Sr{sub x}CrO{sub 3} compared with sintering or plasma spray method. (2) For the complicated material such as perovskite materials, the difference between the composition of a film and that of a target material is generally small. (3) It can fabricate a thick ceramics film by improving of the deposition rate. For example, Al{sub 2}O{sub 3} thick films of 50{mu}m can be fabricated with the deposition rate of approximately 5{mu}m/h industrially. In this paper, the dependence of residual stress on the deposition conditions is defined and mechanical properties of these materials are estimated from the results of the experiments.

  10. Improvement of cathode-electrolyte interfaces of tubular solid oxide fuel cells by fabricating dense YSZ electrolyte membranes with indented surfaces

    NASA Astrophysics Data System (ADS)

    Dong, Dehua; Liu, Mingfei; Xie, Kui; Sheng, Jin; Wang, Yonghong; Peng, Xiaobo; Liu, Xingqin; Meng, Guangyao

    To improve cathode-electrolyte interfaces of solid oxide fuel cells (SOFCs), dense YSZ electrolyte membranes with indented surfaces were fabricated on tubular NiO/YSZ anode supports by two comparable methods. Electrochemistry impedance spectroscopy (EIS) and current-voltage tests of the cells were carried out to characterize the cathode-electrolyte interfaces. Results showed that the electrode polarization resistances of the modified cells were reduced by 52% and 35% at 700 °C, and the maximum power densities of cells were remarkably increased, even by 146.6% and 117.8% at lower temperature (700 °C), respectively. The indented surfaces extended the active zone of cathode and enhanced interfacial adhesion, which led to the major improvement in the cell performance.

  11. 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.

  12. Apoptotic tubular cell death during acute renal allograft rejection.

    PubMed

    Wever, P C; Aten, J; Rentenaar, R J; Hack, C E; Koopman, G; Weening, J J; ten Berge, I J

    1998-01-01

    Tubular cells are important targets during acute renal allograft rejection and induction of apoptosis might be a mechanism of tubular cell destruction. Susceptibility to induction of apoptosis is regulated by the homologous Bcl-2 and Bax proteins. Expression of Bcl-2 and Bax is regulated by p53, which down-regulates expression of Bcl-2, while simultaneously up-regulating expression of Bax. We studied apoptotic tubular cell death in 10 renal allograft biopsies from transplant recipients with acute rejection by in situ end-labelling and the DNA-binding fluorochrome propidium iodide. Tubular expression of p53, Bcl-2 and Bax was studies by immunohistochemistry. Five renal allograft biopsies from transplant recipients with uncomplicated clinical course and histologically normal renal tissue present in nephrectomy specimens from 4 patients with renal adenocarcinoma served as control specimens. Apoptotic cells and apoptotic bodies were detected in tubular epithelia and tubular lumina in 9 out of 10 acute rejection biopsies. In control renal tissue, apoptotic cells were detected in 1 biopsy only. Compared to control renal tissue, acute renal allograft rejection was, furthermore, associated with a shift in the ratio of Bcl-2 to Bax in favour of Bax in tubular epithelia and increased expression of p53 in tubular nuclei. These observations demonstrate that apoptosis contributes in part to tubular cell destruction during acute renal allograft rejection. In accordance, the shift in the ratio of Bcl-2 to Bax in favour of Bax indicates increased susceptibility of tubular epithelia to induction of apoptosis. The expression of p53 in tubular nuclei during acute renal allograft rejection indicates the presence of damaged DNA, which can be important in initiation of part of the observed apoptosis. These findings elucidate part of the mechanisms controlling apoptotic tubular cell death during acute renal allograft rejection.

  13. 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).

  14. Discovery during Hydrogen Annealing: Formation of Nanoscale Fluorocarbon Tubular Structures

    NASA Astrophysics Data System (ADS)

    Hao, Xiuchun; Tanaka, Sinya; Masuda, Atsuhiko; Maenaka, Kazusuke; Higuchi, Kohei

    2013-09-01

    A novel fabrication method for nanoscale tubular structures is presented in this paper. The tubular structures can be obtained by heating single-crystal silicon trenches or pillars formed by the inductively coupled plasma reactive-ion etching (ICP-RIE) Bosch process in hydrogen ambient. The importance of initial vacuum in the reaction chamber for tube formation and the tube formation mechanism were discussed. The components and sidewall size of the tubular structure were also studied to verify that the tube is made of the fluorocarbon (CF) passivation layer deposited by the Bosch process. The CF tubular structure would be a promising structure for BioMEMS.

  15. Tubular reabsorption of calcium in normal and hypercalciuric subjects

    PubMed Central

    Peacock, M.; Nordin, B. E. C.

    1968-01-01

    Tubular reabsorption and excretion of calcium were studied at different levels of filtered calcium by means of calcium infusion in normal and hypercalciuric subjects and in patients with idiopathic nephrolithiasis. Calcium reabsorption and excretion rose linearly with filtered load and in no case was a maximum tubular reabsorptive capacity for calcium reached. No decrease in tubular reabsorption of calcium was found in hypercalciuric as compared with normocalciuric subjects, and no difference in tubular reabsorption was found between patients with idiopathic nephrolithiasis and normal subjects. Calcium excretion and reabsorption calculated from the endogenous creatinine clearance during calcium infusion were virtually identical with the corresponding values calculated from the inulin clearance. PMID:5699075

  16. 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.

  17. Advanced beaded and tubular structural panels

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  18. Tubular vimentin metaplasia in canine nephropathies.

    PubMed

    Vilafranca, M; Domingo, M; Ferrer, L

    1994-09-01

    The expression of the intermediate filament vimentin was examined immunocytochemically in 17 cases of histologically confirmed primary canine nephropathy, and compared with its expression in normal canine kidney. In normal renal tissue, the expression of vimentin was restricted to glomerular elements, but in all cases of chronic interstitial nephritis it extended to the cortical tubular epithelia, and was correlated with the degree of tubulo-interstitial damage. Three of four cases of renal cell carcinoma had vimentin reactivity in neoplastic cells. In only one case of familial renal disease was vimentin expressed in scattered epithelial cells of the cortical tubules.

  19. Fuel flexibility study of an integrated 25 kW SOFC reformer system

    NASA Astrophysics Data System (ADS)

    Yi, Yaofan; Rao, Ashok D.; Brouwer, Jacob; Samuelsen, G. Scott

    The operation of solid oxide fuel cells on various fuels, such as natural gas, biogas and gases derived from biomass or coal gasification and distillate fuel reforming has been an active area of SOFC research in recent years. In this study, we develop a theoretical understanding and thermodynamic simulation capability for investigation of an integrated SOFC reformer system operating on various fuels. The theoretical understanding and simulation results suggest that significant thermal management challenges may result from the use of different types of fuels in the same integrated fuel cell reformer system. Syngas derived from coal is simulated according to specifications from high-temperature entrained bed coal gasifiers. Diesel syngas is approximated from data obtained in a previous NFCRC study of JP-8 and diesel operation of the integrated 25 kW SOFC reformer system. The syngas streams consist of mixtures of hydrogen, carbon monoxide, carbon dioxide, methane and nitrogen. Although the SOFC can tolerate a wide variety in fuel composition, the current analyses suggest that performance of integrated SOFC reformer systems may require significant operating condition changes and/or system design changes in order to operate well on this variety of fuels.

  20. Cold start dynamics and temperature sliding observer design of an automotive SOFC APU

    NASA Astrophysics Data System (ADS)

    Lin, Po-Hsu; Hong, Che-Wun

    This paper presents a dynamic model for studying the cold start dynamics and observer design of an auxiliary power unit (APU) for automotive applications. The APU is embedded with a solid oxide fuel cell (SOFC) stack which is a quiet and pollutant-free electric generator; however, it suffers from slow start problem from ambient conditions. The SOFC APU system equips with an after-burner to accelerate the start-up transient in this research. The combustion chamber burns the residual fuel (and air) left from the SOFC to raise the exhaust temperature to preheat the SOFC stack through an energy recovery unit. Since thermal effect is the dominant factor that influences the SOFC transient and steady performance, a nonlinear real-time sliding observer for stack temperature was implemented into the system dynamics to monitor the temperature variation for future controller design. The simulation results show that a 100 W APU system in this research takes about 2 min (in theory) for start-up without considering the thermal limitation of the cell fracture.

  1. Feasibility study for SOFC-GT hybrid locomotive power part II. System packaging and operating route simulation

    NASA Astrophysics Data System (ADS)

    Martinez, Andrew S.; Brouwer, Jacob; Samuelsen, G. Scott

    2012-09-01

    This work assesses the feasibility of Solid Oxide Fuel Cell-Gas Turbine (SOFC-GT) hybrid power systems for use as the prime mover in freight locomotives. The available space in a diesel engine-powered locomotive is compared to that required for an SOFC-GT system, inclusive of fuel processing systems necessary for the SOFC-GT. The SOFC-GT space requirement is found to be similar to current diesel engines, without consideration of the electrical balance of plant. Preliminary design of the system layout within the locomotive is carried out for illustration. Recent advances in SOFC technology and implications of future improvements are discussed as well. A previously-developed FORTRAN model of an SOFC-GT system is then augmented to simulate the kinematics and power notching of a train and its locomotives. The operation of the SOFC-GT-powered train is investigated along a representative route in Southern California, with simulations presented for diesel reformate as well as natural gas reformate and hydrogen as fuels. Operational parameters and difficulties are explored as are comparisons of expected system performance to modern diesel engines. It is found that even in the diesel case, the SOFC-GT system provides significant savings in fuel and CO2 emissions, making it an attractive option for the rail industry.

  2. Mechansims and components of renal tubular acidification.

    PubMed Central

    Cassola, A C; Giebisch, G; Malnic, G

    1977-01-01

    1. Renal cortical tubules of control and acetazolamide infused rats were perfused with 100 mM phosphate buffer at pH 5-5. The rate of alkalinization was measured by means of antimony micro-electrodes and was used to compute passive H ion fluxes from lumen to blood across the proximal and distal tubular epithelium. 2. The importance of other ionic movements that might contribute to pH changes of luminal buffers (chloride inflow into the lumen and bicarbonate diffusion across the epithelium) was assessed but found to be minor. H ion movements accounted for the majority of the observed pH changes. 3. H ion permeability of the tubular wall was calculated from the measured H fluxes and transepithelial concentration differences. It was 1-10 cm/sec, several orders of magnitude larger than those for other ions. However, such values are compatible with the mobility of protons in a medium of structure water within the limiting membrane. 4. A kinetic analysis of the mechanism of movement of H ions across the renal tubule is presented on the basis of experiments in which acidification and alkalinization of luminal buffers was followed in stationary microperfusions. The data are compatible with a pump-leak system in the proximal tubule, and with a model with low H ion permeability and a gradient dependent pump in the distal tubule. PMID:17737

  3. Context preserving maps of tubular structures.

    PubMed

    Marino, Joseph; Zeng, Wei; Gu, Xianfeng; Kaufman, Arie

    2011-12-01

    When visualizing tubular 3D structures, external representations are often used for guidance and display, and such views in 2D can often contain occlusions. Virtual dissection methods have been proposed where the entire 3D structure can be mapped to the 2D plane, though these will lose context by straightening curved sections. We present a new method of creating maps of 3D tubular structures that yield a succinct view while preserving the overall geometric structure. Given a dominant view plane for the structure, its curve skeleton is first projected to a 2D skeleton. This 2D skeleton is adjusted to account for distortions in length, modified to remove intersections, and optimized to preserve the shape of the original 3D skeleton. Based on this shaped 2D skeleton, a boundary for the map of the object is obtained based on a slicing path through the structure and the radius around the skeleton. The sliced structure is conformally mapped to a rectangle and then deformed via harmonic mapping to match the boundary placement. This flattened map preserves the general geometric context of a 3D object in a 2D display, and rendering of this flattened map can be accomplished using volumetric ray casting. We have evaluated our method on real datasets of human colon models.

  4. Characterization of Atomic and Electronic Structures of Electrochemically Active SOFC Cathode Surfaces

    SciTech Connect

    Kevin Blinn; Yongman Choi; Meilin Liu

    2009-08-11

    The objective of this project is to gain a fundamental understanding of the oxygen-reduction mechanism on mixed conducting cathode materials by means of quantum-chemical calculations coupled with direct experimental measurements, such as vibrational spectroscopy. We have made progress in the elucidation of the mechanisms of oxygen reduction of perovkite-type cathode materials for SOFCs using these quantum chemical calculations. We established computational framework for predicting properties such as oxygen diffusivity and reaction rate constants for adsorption, incorporation, and TPB reactions, and formulated predictions for LSM- and LSC-based cathode materials. We have also further developed Raman spectroscopy as well as SERS as a characterization tool for SOFC cathode materials. Raman spectroscopy was used to detect chemical changes in the cathode from operation conditions, and SERS was used to probe for pertinent adsorbed species in oxygen reduction. However, much work on the subject of unraveling oxygen reduction for SOFC cathodes remains to be done.

  5. Quantifying the Interfacial Strength of Oxide Scale and SS 441 Substrate Used in SOFC

    SciTech Connect

    Liu, Wenning N.; Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2009-08-15

    Under a typical SOFC working environment, oxide scale will grow on the metallic interconnects in oxidant environment. The growth of the oxide scale induces the growth stresses in the oxide scale and on the scale/substrate interface combined with the thermal stresses induced by thermal expansion coefficient mismatch between the oxide scale and the substrate, which may lead to scale delamination/buckling and eventual spallation during stack cooling, even leading to serious cell performance degradation. Therefore, the interfacial adhesion strength between the oxide scale and substrate is crucial to the reliability and durability of the metallic interconnect in SOFC operating environments. As a powerful contender of ferritic interconnects used in SOFC, its interfacial strength between the oxide scale and SS 441 substrate is very important for its application. In this paper, we applied an integrated experimental/analytical methodology to quantify the interfacial adhesion strength between oxide scale and metallic interconnect. The predicted interfacial strength is discussed in detailed

  6. Application of mica glass-ceramics as gas-sealing materials for SOFC

    SciTech Connect

    Yamamoto, Tohru; Itoh, Hibiki; Mori, Masashi; Mori, Noriyuki; Abe, Toshio

    1995-12-31

    Adaptability of mica glass-ceramics as gas-sealing material for SOFCs has been investigated. Thermal expansion coefficient, {alpha}=9.5--12.0 {times} 10{sup {minus}6}/C, agreed with those of SOFC`s constituent materials. Solid state electrolyte (8mol% yttria-stabilized zirconia, 8YSZ) and separator (La{sub 0.8}Ca{sub 0.22}CrO{sub 3}) joined with mica glass-ceramics in a temperature range of about 1,000 to 1,300 C. No chemical reaction was observed at the interface between mica glass-ceramics and electrolyte. An interface between mica glass-ceramics and separator was formed due to chemical reactions. A single cell unit which was made up of a single cell and separators was manufactured for testing using this mica glass-ceramics.

  7. Glass Sealing in Planar SOFC Stacks and Chemical Stability of Seal Interfaces

    SciTech Connect

    Yang, Z Gary; Xia, Gordon; Meinhardt, Kerry D.; Weil, K. Scott; Stevenson, Jeffry W.

    2005-03-01

    In intermediate temperature planar SOFC stacks, the interconnect, which is typically made from cost-effective oxidation resistant high temperature alloys, is typically sealed to the ceramic PEN (Positive electrode-Electrolyte-Negative electrode) by a sealing glass. To maintain the structural stability and minimize the degradation of stack performance, the sealing glass has to be chemically compatible with the PEN and alloy interconnects. In the present study, the chemical compatibility of a barium-calcium-aluminosilicate (BCAS) based glass-ceramic (specifically developed as a sealant in SOFC stacks) with a number of selected oxidation resistant high temperature alloys, as well as the YSZ electrolyte, was evaluated. This paper reports the results of that study, with a particular focus on Crofer22 APU, a new ferritic stainless steel that was developed specifically for SOFC interconnect applications.

  8. Modeling the Electrochemistry of an SOFC through the Electrodes and Electrolyte

    SciTech Connect

    Ryan, Emily M.; Recknagle, Kurtis P.; Khaleel, Mohammad A.

    2011-12-01

    This paper describes a distributed electrochemistry model of the solid oxide fuel cell (SOFC) electrodes and electrolyte. The distributed electrochemistry (DEC) model solves the transport, reactions, and electric potential through the thickness of the SOFC electrodes. The DEC model allows the local conditions within the electrodes to be studied and allows for a better understanding of how electrochemical and microstructural parameters affect the electrodes. In this paper the governing equations and implementation of the DEC model are presented along with several case studies which are used to investigate the sensitivity of the cathode to the microstructural and electrochemical parameters of the model and to explore methods of improving the electrochemical performance of the SOFC cathode.

  9. 10kW SOFC POWER SYSTEM COMMERCIALIZATION

    SciTech Connect

    Dan Norrick; Charles Vesely; Todd Romine; Brad Palmer; Greg Rush; Eric Barringer; Milind Kantak; Cris DeBellis

    2003-02-01

    Participants in the SECA 10 kW SOFC Power System Commercialization project include Cummins Power Generation (CPG), the power generation arm of Cummins, Inc., SOFCo-EFS Holdings, LLC (formerly McDermott Technology, Inc.), the fuel cell and fuel processing research and development arm of McDermott International Inc., M/A-COM, the Multi-Layer Ceramics (MLC) processing and manufacturing arm of Tyco Electronics, and Ceramatec, a materials technology development company. CPG functions in the role of prime contractor and system integrator. SOFCo-EFS is responsible for the design and development of the hot box assembly, including the SOFC stack(s), heat exchanger(s), manifolding, and fuel reformer. M/A-COM and SOFCo-EFS are jointly responsible for development of the MLC manufacturing processes, and Ceramatec provides technical support in materials development. In October 2002, McDermott announced its intention to cease operations at McDermott Technology, Inc. (MTI) as of December 31, 2002. This decision was precipitated by several factors, including the announced tentative settlement of the B&W Bankruptcy which would result in all of the equity of B&W being conveyed to a trust, thereby eliminating McDermott's interest in the company, and the desire to create a separate fuel cell entity to facilitate its commercial development. The new fuel cell entity is named SOFCo-EFS Holdings, LLC. All of McDermott's solid oxide fuel cell and fuel processing work will be conducted by SOFCo-EFS, using personnel previously engaged in that work. SOFCo-EFS will continue to be located in the Alliance, OH facility and use the existing infrastructure and test facilities for its activities. While the effort needed to accomplish this reorganization has detracted somewhat from SOFCo's efficiency during the fourth quarter, we believe the improved focus on the core fuel cell and fuel reformation resulting from the reorganization will have a positive impact on the SECA project in the long run. The

  10. CO2 emission free co-generation of energy and ethylene in hydrocarbon SOFC reactors with a dehydrogenation anode.

    PubMed

    Fu, Xian-Zhu; Lin, Jie-Yuan; Xu, Shihong; Luo, Jing-Li; Chuang, Karl T; Sanger, Alan R; Krzywicki, Andrzej

    2011-11-21

    A dehydrogenation anode is reported for hydrocarbon proton conducting solid oxide fuel cells (SOFCs). A Cu-Cr(2)O(3) nanocomposite is obtained from CuCrO(2) nanoparticles as an inexpensive, efficient, carbon deposition and sintering tolerant anode catalyst. A SOFC reactor is fabricated using a Cu-Cr(2)O(3) composite as a dehydrogenation anode and a doped barium cerate as a proton conducting electrolyte. The protonic membrane SOFC reactor can selectively convert ethane to valuable ethylene, and electricity is simultaneously generated in the electrochemical oxidative dehydrogenation process. While there are no CO(2) emissions, traces of CO are present in the anode exhaust when the SOFC reactor is operated at over 700 °C. A mechanism is proposed for ethane electro-catalytic dehydrogenation over the Cu-Cr(2)O(3) catalyst. The SOFC reactor also has good stability for co-generation of electricity and ethylene at 700 °C. PMID:21984357

  11. Advanced Measurement and Modeling Techniques for Improved SOFC Cathodes

    SciTech Connect

    Stuart Adler; L. Dunyushkina; S. Huff; Y. Lu; J. Wilson

    2006-12-31

    The goal of this project was to develop an improved understanding of factors governing performance and degradation of mixed-conducting SOFC cathodes. Two new diagnostic tools were developed to help achieve this goal: (1) microelectrode half-cells for improved isolation of cathode impedance on thin electrolytes, and (2) nonlinear electrochemical impedance spectroscopy (NLEIS), a variant of traditional impedance that allows workers to probe nonlinear rates as a function of frequency. After reporting on the development and efficacy of these tools, this document reports on the use of these and other tools to better understand performance and degradation of cathodes based on the mixed conductor La{sub 1-x}Sr{sub x}CoO{sub 3-{delta}} (LSC) on gadolinia or samaria-doped ceria (GDC or SDC). We describe the use of NLEIS to measure O{sub 2} exchange on thin-film LSC electrodes, and show that O{sub 2} exchange is most likely governed by dissociative adsorption. We also describe parametric studies of porous LSC electrodes using impedance and NLEIS. Our results suggest that O{sub 2} exchange and ion transport co-limit performance under most relevant conditions, but it is O{sub 2} exchange that is most sensitive to processing, and subject to the greatest degradation and sample-to-sample variation. We recommend further work that focuses on electrodes of well-defined or characterized geometry, and probes the details of surface structure, composition, and impurities. Parallel work on primarily electronic conductors (LSM) would also be of benefit to developers, and to improved understanding of surface vs. bulk diffusion.

  12. Innovative Self-Healing Seals for Solid Oxide Fuel Cells (SOFC)

    SciTech Connect

    Raj Singh

    2012-06-30

    Solid oxide fuel cell (SOFC) technology is critical to several national initiatives. Solid State Energy Conversion Alliance (SECA) addresses the technology needs through its comprehensive programs on SOFC. A reliable and cost-effective seal that works at high temperatures is essential to the long-term performance of the SOFC for 40,000 hours at 800°C. Consequently, seals remain an area of highest priority for the SECA program and its industry teams. An innovative concept based on self-healing glasses was advanced and successfully demonstrated through seal tests for 3000 hours and 300 thermal cycles to minimize internal stresses under both steady state and thermal transients for making reliable seals for the SECA program. The self-healing concept requires glasses with low viscosity at the SOFC operating temperature of 800°C but this requirement may lead to excessive flow of the glass in areas forming the seal. To address this challenge, a modification to glass properties by addition of particulate fillers is pursued in the project. The underlying idea is that a non-reactive ceramic particulate filler is expected to form glass-ceramic composite and increase the seal viscosity thereby increasing the creep resistance of the glass-composite seals under load. The objectives of the program are to select appropriate filler materials for making glass-composite, fabricate glass-composites, measure thermal expansion behaviors, and determine stability of the glass-composites in air and fuel environments of a SOFC. Self-healing glass-YSZ composites are further developed and tested over a longer time periods under conditions typical of the SOFCs to validate the long-term stability up to 2000 hours. The new concepts of glass-composite seals, developed and nurtured in this program, are expected to be cost-effective as these are based on conventional processing approaches and use of the inexpensive materials.

  13. Effect of PEG additive on anode microstructure and cell performance of anode-supported MT-SOFCs fabricated by phase inversion method

    NASA Astrophysics Data System (ADS)

    Ren, Cong; Liu, Tong; Maturavongsadit, Panita; Luckanagul, Jittima Amie; Chen, Fanglin

    2015-04-01

    Anode-supported micro-tubular solid oxide fuel cells (MT-SOFCs) have been fabricated by phase inversion method. For the anode support preparation, N-methyl-2-pyrrolidone (NMP), polyethersulfone (PESf) and poly ethylene glycol (PEG) were applied as solvent, polymer binder and additive, respectively. The effect of molecular weight and amount of PEG additive on the thermodynamics of the casting solutions was characterized by measuring the coagulation value. Viscosity of the casting slurries was also measured and the influence of PEG additive on viscosity was studied and discussed. The presence of PEG in the casting slurry can significantly influence the final anode support microstructure. Based on the microstructure result and the measured gas permeation value, two anode supports were selected for cell fabrication. For cell with the anode support fabricated using slurry with PEG additive, a maximum cell power density of 704 mW cm-2 is obtained at 750 °C with humidified hydrogen as fuel and ambient air as oxidant; cell fabricated without any PEG additive shows the peak cell power density of 331 mW cm-2. The relationship between anode microstructure and cell performance was discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-20

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

  16. Digital Manufacturing of Gradient Meshed SOFC Sealing Composites with Self-Healing Capabilities

    SciTech Connect

    Kathy Lu; Christopher Story; W.T. Reynolds

    2007-12-21

    Solid oxide fuel cells (SOFC) hold great promise for clean power generation. However, high temperature stability and long term durability of the SOFC components have presented serious problems in SOFC technological advancement and commercialization. The seals of the fuel cells are the most challenging area to address. A high temperature gas seal is highly needed which is durable against cracking and gas leakage during thermal cycling and extended operation. This project investigates a novel composite seal by integrating 3D printed shape memory alloy (SMA) wires into a glass matrix. The SMA we use is TiNiHf and the glass matrix we use is SrO-La{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3}-SiO{sub 2} (SLABS). Dilatometry shows to be an extremely useful tool in providing the CTEs. It pinpoints regions of different CTEs under simulated SOFC thermal cycles for the same glass. For the studied SLABS glass system, the region with the greatest CTE mismatch between the glass seal and the adjacent components is 40-500 C, the typical heating and cooling regions for SOFCs. Even for low temperature SOFC development, this region is still present and needs to be addressed. We have demonstrated that the proposed SLABS glass has great potential in mitigating the thermal expansion mismatch issues that are limiting the operation life of SOFCs. TiNiHf alloy has been successfully synthesized with the desired particle size for the 3DP process. The TiNiHf SMA shape memory effect very desirably overlaps with the problematic low CTE region of the glass. This supports the design intent that the gradient structure transition, phase transformation toughening, and self-healing of the SMA can be utilized to mitigate/eliminate the seal problem. For the 3DP process, a new binder has been identified to match with the specific chemistry of the SMA particles. This enables us to directly print SMA particles. Neutron diffraction shows to be an extremely useful tool in providing information

  17. Improvement of capabilities of the Distributed Electrochemistry Modeling Tool for investigating SOFC long term performance

    SciTech Connect

    Gonzalez Galdamez, Rinaldo A.; Recknagle, Kurtis P.

    2012-04-30

    This report provides an overview of the work performed for Solid Oxide Fuel Cell (SOFC) modeling during the 2012 Winter/Spring Science Undergraduate Laboratory Internship at Pacific Northwest National Laboratory (PNNL). A brief introduction on the concept, operation basics and applications of fuel cells is given for the general audience. Further details are given regarding the modifications and improvements of the Distributed Electrochemistry (DEC) Modeling tool developed by PNNL engineers to model SOFC long term performance. Within this analysis, a literature review on anode degradation mechanisms is explained and future plans of implementing these into the DEC modeling tool are also proposed.

  18. Dietary protein alters tubular iron accumulation after partial nephrectomy.

    PubMed

    Nankivell, B J; Tay, Y C; Boadle, R A; Harris, D C

    1994-04-01

    Reactive oxygen species (ROS) have been implicated in progression of disease in the rat remnant kidney (RK) model of chronic renal failure. Substantial amounts of iron accumulate in proximal tubular lysosomes of RK and could damage tubules by ROS generation. The effect of dietary protein intake on ROS, tubular damage and iron accumulation assessed by energy dispersive analysis was determined in RK (5/6 nephrectomy, N = 12) and sham-operated kidneys (SO, N = 10). In RK, mean lysosomal iron concentration, urinary iron and protein excretion and morphological damage were increased and GFR decreased. Dietary protein loading (40% vs. 12%) increased the number of iron-containing lysosomes (P < 0.05) and the mean lysosomal iron (P < 0.02) in proximal tubular cells after four weeks. In RK, high protein diet increased renal weight (P < 0.01), numerical density of iron-containing lysosomes and tubular damage (both P < 0.05). ROS generation, assessed by tissue and plasma malondialdehyde (MDA), was also increased (both P < 0.05). Plasma MDA correlated with tubular iron accumulation (r = 0.75). In RK fed a high protein diet (N = 18) treatment with the iron-chelator desferrioxamine reduced serum iron, urinary volume, and tubular iron accumulation and damage compared to controls (P < 0.01). In summary, in RK dietary protein manipulation altered urinary iron and protein excretion, proximal tubular iron accumulation, renal cortical ROS generation and ultrastructural damage. Desferrioxamine treatment reduced tubular lysosomal iron and ultrastructural damage. These results suggest a role for tubular iron as a determinant of tubular injury associated with dietary protein loading in rats with partial nephrectomy.

  19. Renal tubular secretion of glutathione (GSH)

    SciTech Connect

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

    1986-05-01

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

  20. Loss of tubular creatinine secretion as the only sign of tubular proximal cell dysfunction in light chain proximal tubulopathy

    PubMed Central

    Stehlé, Thomas; Vignon, Marguerite; Flamant, Martin; Figueres, Marie-Lucile; Rabant, Marion; Rodenas, Anita; Noël, Laure-Hélène; Arnulf, Bertrand; Vidal-Petiot, Emmanuelle

    2016-01-01

    Abstract Light chain proximal tubulopathy (LCPT) is a rare disease, characterized by cytoplasmic inclusions of light chain (usually kappa) immunoglobulins. Clinical presentation is usually a Fanconi syndrome. The proximal tubular dysfunction can be incomplete, and exceptional cases of LCPT without any tubular dysfunction have even been described. Here, we report a case of LCPT in which the only sign of proximal tubulopathy is the absence of secretion of creatinine, as assessed by the simultaneous measurement of renal clearance of creatinine and 51CrEDTA. The loss of tubular creatinine secretion as a sign of tubular proximal cell dysfunction ought to be identified in patients with light chain proximal tubulopathy as it leads to a clinically relevant underestimation of GFR by the creatinine-derived equations. The prevalence and prognostic significance of this particular proximal tubular damage in LCPT remain to be determined. PMID:27367983

  1. Feasibility study for SOFC-GT hybrid locomotive power: Part I. Development of a dynamic 3.5 MW SOFC-GT FORTRAN model

    NASA Astrophysics Data System (ADS)

    Martinez, Andrew S.; Brouwer, Jacob; Samuelsen, G. Scott

    2012-09-01

    This work presents the development of a dynamic SOFC-GT hybrid system model applied to a long-haul freight locomotive in operation. Given the expectations of the rail industry, the model is used to develop a preliminary analysis of the proposed system's operational capability on conventional diesel fuel as well as natural gas and hydrogen as potential fuels in the future. It is found that operation of the system on all three of these fuels is feasible with favorable efficiencies and reasonable dynamic response. The use of diesel fuel reformate in the SOFC presents a challenge to the electrochemistry, especially as it relates to control and optimization of the fuel utilization in the anode compartment. This is found to arise from the large amount of carbon monoxide in diesel reformate that is fed to the fuel cell, limiting the maximum fuel utilization possible. This presents an opportunity for further investigations into carbon monoxide electrochemical oxidation and/or system integration studies where the efficiency of the fuel reformer can be balanced against the needs of the SOFC.

  2. Oxidation Resistant, Cr Retaining, Electrically Conductive Coatings on Metallic Alloys for SOFC Interconnects

    SciTech Connect

    Vladimir Gorokhovsky

    2008-03-31

    This report describes significant results from an on-going, collaborative effort to enable the use of inexpensive metallic alloys as interconnects in planar solid oxide fuel cells (SOFCs) through the use of advanced coating technologies. Arcomac Surface Engineering, LLC, under the leadership of Dr. Vladimir Gorokhovsky, is investigating filtered-arc and filtered-arc plasma-assisted hybrid coating deposition technologies to promote oxidation resistance, eliminate Cr volatility, and stabilize the electrical conductivity of both standard and specialty steel alloys of interest for SOFC metallic interconnect (IC) applications. Arcomac has successfully developed technologies and processes to deposit coatings with excellent adhesion, which have demonstrated a substantial increase in high temperature oxidation resistance, stabilization of low Area Specific Resistance values and significantly decrease Cr volatility. An extensive matrix of deposition processes, coating compositions and architectures was evaluated. Technical performance of coated and uncoated sample coupons during exposures to SOFC interconnect-relevant conditions is discussed, and promising future directions are considered. Cost analyses have been prepared based on assessment of plasma processing parameters, which demonstrate the feasibility of the proposed surface engineering process for SOFC metallic IC applications.

  3. Extremely thin bilayer electrolyte for solid oxide fuel cells (SOFCs) fabricated by chemical solution deposition (CSD).

    PubMed

    Oh, Eun-Ok; Whang, Chin-Myung; Lee, Yu-Ri; Park, Sun-Young; Prasad, Dasari Hari; Yoon, Kyung Joong; Son, Ji-Won; Lee, Jong-Ho; Lee, Hae-Weon

    2012-07-01

    An extremely thin bilayer electrolyte consisting of yttria-stabilized zirconia (YSZ) and gadolinia-doped ceria (GDC) is successfully fabricated on a sintered NiO-YSZ substrate. Major processing flaws are effectively eliminated by applying local constraints to YSZ nanoparticles, and excellent open circuit voltage and cell performance are demonstrated in a solid oxide fuel cell (SOFC) at intermediate operating temperatures.

  4. The financial viability of an SOFC cogeneration system in single-family dwellings

    NASA Astrophysics Data System (ADS)

    Alanne, Kari; Saari, Arto; Ugursal, V. Ismet; Good, Joel

    In the near future, fuel cell-based residential micro-CHP systems will compete with traditional methods of energy supply. A micro-CHP system may be considered viable if its incremental capital cost compared to its competitors equals to cumulated savings during a given period of time. A simplified model is developed in this study to estimate the operation of a residential solid oxide fuel cell (SOFC) system. A comparative assessment of the SOFC system vis-à-vis heating systems based on gas, oil and electricity is conducted using the simplified model for a single-family house located in Ottawa and Vancouver. The energy consumption of the house is estimated using the HOT2000 building simulation program. A financial analysis is carried out to evaluate the sensitivity of the maximum allowable capital cost with respect to system sizing, acceptable payback period, energy price and the electricity buyback strategy of an energy utility. Based on the financial analysis, small (1-2 kW e) SOFC systems seem to be feasible in the considered case. The present study shows also that an SOFC system is especially an alternative to heating systems based on oil and electrical furnaces.

  5. Extended Durability Testing of an External Fuel Processor for a Solid Oxide Fuel Cell (SOFC)

    SciTech Connect

    Mark Perna; Anant Upadhyayula; Mark Scotto

    2012-11-05

    Durability testing was performed on an external fuel processor (EFP) for a solid oxide fuel cell (SOFC) power plant. The EFP enables the SOFC to reach high system efficiency (electrical efficiency up to 60%) using pipeline natural gas and eliminates the need for large quantities of bottled gases. LG Fuel Cell Systems Inc. (formerly known as Rolls-Royce Fuel Cell Systems (US) Inc.) (LGFCS) is developing natural gas-fired SOFC power plants for stationary power applications. These power plants will greatly benefit the public by reducing the cost of electricity while reducing the amount of gaseous emissions of carbon dioxide, sulfur oxides, and nitrogen oxides compared to conventional power plants. The EFP uses pipeline natural gas and air to provide all the gas streams required by the SOFC power plant; specifically those needed for start-up, normal operation, and shutdown. It includes a natural gas desulfurizer, a synthesis-gas generator and a start-gas generator. The research in this project demonstrated that the EFP could meet its performance and durability targets. The data generated helped assess the impact of long-term operation on system performance and system hardware. The research also showed the negative impact of ambient weather (both hot and cold conditions) on system operation and performance.

  6. Effect of Samarium Oxide on the Electrical Conductivity of Plasma-Sprayed SOFC Anodes

    NASA Astrophysics Data System (ADS)

    Panahi, S. N.; Samadi, H.; Nemati, A.

    2016-10-01

    Solid oxide fuel cells (SOFCs) are rapidly becoming recognized as a new alternative to traditional energy conversion systems because of their high energy efficiency. From an ecological perspective, this environmentally friendly technology, which produces clean energy, is likely to be implemented more frequently in the future. However, the current SOFC technology still cannot meet the demands of commercial applications due to temperature constraints and high cost. To develop a marketable SOFC, suppliers have tended to reduce the operating temperatures by a few hundred degrees. The overall trend for SOFC materials is to reduce their service temperature of electrolyte. Meanwhile, it is important that the other components perform at the same temperature. Currently, the anodes of SOFCs are being studied in depth. Research has indicated that anodes based on a perovskite structure are a more promising candidate in SOFCs than the traditional system because they possess more favorable electrical properties. Among the perovskite-type oxides, SrTiO3 is one of the most promising compositions, with studies demonstrating that SrTiO3 exhibits particularly favorable electrical properties in contrast with other perovskite-type oxides. The main purpose of this article is to describe our study of the effect of rare-earth dopants with a perovskite structure on the electrical behavior of anodes in SOFCs. Sm2O3-doped SrTiO3 synthesized by a solid-state reaction was coated on substrate by atmospheric plasma spray. To compare the effect of the dopant on the electrical conductivity of strontium titanate, different concentrations of Sm2O3 were used. The samples were then investigated by x-ray diffraction, four-point probe at various temperatures (to determine the electrical conductivity), and a scanning electron microscope. The study showed that at room temperature, nondoped samples have a higher electrical resistance than doped samples. As the temperature was increased, the electrical

  7. Effect of Samarium Oxide on the Electrical Conductivity of Plasma-Sprayed SOFC Anodes

    NASA Astrophysics Data System (ADS)

    Panahi, S. N.; Samadi, H.; Nemati, A.

    2016-05-01

    Solid oxide fuel cells (SOFCs) are rapidly becoming recognized as a new alternative to traditional energy conversion systems because of their high energy efficiency. From an ecological perspective, this environmentally friendly technology, which produces clean energy, is likely to be implemented more frequently in the future. However, the current SOFC technology still cannot meet the demands of commercial applications due to temperature constraints and high cost. To develop a marketable SOFC, suppliers have tended to reduce the operating temperatures by a few hundred degrees. The overall trend for SOFC materials is to reduce their service temperature of electrolyte. Meanwhile, it is important that the other components perform at the same temperature. Currently, the anodes of SOFCs are being studied in depth. Research has indicated that anodes based on a perovskite structure are a more promising candidate in SOFCs than the traditional system because they possess more favorable electrical properties. Among the perovskite-type oxides, SrTiO3 is one of the most promising compositions, with studies demonstrating that SrTiO3 exhibits particularly favorable electrical properties in contrast with other perovskite-type oxides. The main purpose of this article is to describe our study of the effect of rare-earth dopants with a perovskite structure on the electrical behavior of anodes in SOFCs. Sm2O3-doped SrTiO3 synthesized by a solid-state reaction was coated on substrate by atmospheric plasma spray. To compare the effect of the dopant on the electrical conductivity of strontium titanate, different concentrations of Sm2O3 were used. The samples were then investigated by x-ray diffraction, four-point probe at various temperatures (to determine the electrical conductivity), and a scanning electron microscope. The study showed that at room temperature, nondoped samples have a higher electrical resistance than doped samples. As the temperature was increased, the electrical

  8. Tubular duplication of the oesophagus presenting with dysphagia.

    PubMed

    Saha, A K; Kundu, A K

    2014-06-01

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

  9. Fabrication and characterization of anode-supported micro-tubular solide oxide fuel cell by phase inversion method

    NASA Astrophysics Data System (ADS)

    Ren, Cong

    Nowadays, the micro-tubular solid oxide fuel cells (MT-SOFCs), especially the anode supported MT-SOFCs have been extensively developed to be applied for SOFC stacks designation, which can be potentially used for portable power sources and vehicle power supply. To prepare MT-SOFCs with high electrochemical performance, one of the main strategies is to optimize the microstructure of the anode support. Recently, a novel phase inversion method has been applied to prepare the anode support with a unique asymmetrical microstructure, which can improve the electrochemical performance of the MT-SOFCs. Since several process parameters of the phase inversion method can influence the pore formation mechanism and final microstructure, it is essential and necessary to systematically investigate the relationship between phase inversion process parameters and final microstructure of the anode supports. The objective of this study is aiming at correlating the process parameters and microstructure and further preparing MT-SOFCs with enhanced electrochemical performance. Non-solvent, which is used to trigger the phase separation process, can significantly influence the microstructure of the anode support fabricated by phase inversion method. To investigate the mechanism of non-solvent affecting the microstructure, water and ethanol/water mixture were selected for the NiO-YSZ anode supports fabrication. The presence of ethanol in non-solvent can inhibit the growth of the finger-like pores in the tubes. With the increasing of the ethanol concentration in the non-solvent, a relatively dense layer can be observed both in the outside and inside of the tubes. The mechanism of pores growth and morphology obtained by using non-solvent with high concentration ethanol was explained based on the inter-diffusivity between solvent and non-solvent. Solvent and non-solvent pair with larger Dm value is benefit for the growth of finger-like pores. Three cells with different anode geometries was

  10. Genetics Home Reference: renal tubular acidosis with deafness

    MedlinePlus

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

  11. 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.

  12. 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)

  13. Autophagy and Tubular Cell Death in the Kidney.

    PubMed

    Havasi, Andrea; Dong, Zheng

    2016-05-01

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

  14. 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.

  15. 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

  16. 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.

  17. Cytocompatibility of a silk fibroin tubular scaffold.

    PubMed

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

    2014-01-01

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

  18. 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.

  19. 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.

  20. Tubular filamentation for laser material processing

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  1. Cadmium, metallothionein and renal tubular toxicity.

    PubMed

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

    1992-01-01

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

  2. Tubular filamentation for laser material processing.

    PubMed

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

    2015-01-01

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

  3. Tubular heart valves from decellularized engineered tissue.

    PubMed

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

    2013-12-01

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

  4. 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

  5. Current status of Westinghouse tubular solid oxide fuel cell program

    SciTech Connect

    Parker, W.G.

    1996-04-01

    In the last ten years the solid oxide fuel cell (SOFC) development program at Westinghouse has evolved from a focus on basic material science to the engineering of fully integrated electric power systems. Our endurance for this cell is 5 to 10 years. To date we have successfully operated at power for over six years. For power plants it is our goal to have operated before the end of this decade a MW class power plant. Progress toward these goals is described.

  6. Electroforming of implantable tubular magnetic microrobots for wireless ophthalmologic applications.

    PubMed

    Chatzipirpiridis, George; Ergeneman, Olgaç; Pokki, Juho; Ullrich, Franziska; Fusco, Stefano; Ortega, José A; Sivaraman, Kartik M; Nelson, Bradley J; Pané, Salvador

    2015-01-28

    Magnetic tubular implantable micro-robots are batch fabricated by electroforming. These microdevices can be used in targeted drug delivery and minimally invasive surgery for ophthalmologic applications. These tubular shapes are fitted into a 23-gauge needle enabling sutureless injections. Using a 5-degree-of-freedom magnetic manipulation system, the microimplants are conveniently maneuvered in biological environments. To increase their functionality, the tubes are coated with biocompatible films and can be successfully filled with drugs.

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

    PubMed

    Nakamura, Kazuyoshi; Komagiri, You; Kubokawa, Manabu

    2012-02-01

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

  8. Tubular atrophy in the pathogenesis of chronic kidney disease progression.

    PubMed

    Schelling, Jeffrey R

    2016-05-01

    The longstanding focus in chronic kidney disease (CKD) research has been on the glomerulus, which is sensible because this is where glomerular filtration occurs, and a large proportion of progressive CKD is associated with significant glomerular pathology. However, it has been known for decades that tubular atrophy is also a hallmark of CKD and that it is superior to glomerular pathology as a predictor of glomerular filtration rate decline in CKD. Nevertheless, there are vastly fewer studies that investigate the causes of tubular atrophy, and fewer still that identify potential therapeutic targets. The purpose of this review is to discuss plausible mechanisms of tubular atrophy, including tubular epithelial cell apoptosis, cell senescence, peritubular capillary rarefaction and downstream tubule ischemia, oxidative stress, atubular glomeruli, epithelial-to-mesenchymal transition, interstitial inflammation, lipotoxicity and Na(+)/H(+) exchanger-1 inactivation. Once a a better understanding of tubular atrophy (and interstitial fibrosis) pathophysiology has been obtained, it might then be possible to consider tandem glomerular and tubular therapeutic strategies, in a manner similar to cancer chemotherapy regimens, which employ multiple drugs to simultaneously target different mechanistic pathways.

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

    PubMed

    Angelelli, Paolo; Hauser, Helwig

    2011-12-01

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

  10. Factors affecting proximal tubular reabsorption during development

    SciTech Connect

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

    1987-01-01

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

  11. Toward high-torque electrostatic tubular motors

    NASA Astrophysics Data System (ADS)

    Helin, Philippe; Bourbon, Gilles; Minotti, Patrice; Fujita, Hiroyuki

    1999-10-01

    A new generation of electrostatic micro-motors is investigated using cooperation of arrayed direct-drive actuators. Electrostatic scratch-drive actuators (SDA), which combine active frictional contact mechanisms with electrostatic actuation, are particularly analyzed. Active polysilicon sheets of 2*3 mm2 that integrate up to several thousands of electrostatic scratch drive actuators are fabricated by silicon surface micro-machining process. Each elementary actuator provides its contribution according to the driving force superposition principle, with internal forces as high as 105uN are available from this sheet. According to their natural flexibility, active polysilicon sheets can be coated onto large surfaces. A new generation of self-assembled tubular electrostatic micromotors is developed using this concept. A prototype of a cylindrical micromotor, whose external diameter and length are 1 mm and 2 mm, respectively, has been realized through the insertion of a flexible active polysilicon sheet at the rotor/motor- frame interface. After final assembling, the sheet has to be jammed onto the chassis, in order to allow the rotor to be moved with respect to the motor frame. Thus, the sheet must be in close contact with both the rotor and the motor frame, whatever the gap, which separates the two macroscopic parts. The problem related to the micro/macro world interfacing is solved during the design of sheet in allowing an out-of- plane motion of SDA in order to provide a self gap compensation, whatever both the thermal expansion effects and the macroscopic machining tolerances. The expected driving characteristics show the interest of both cooperative arrayed microactuators and direct drive frictional mechanisms.

  12. A Distributed Electrochemistry Modeling Tool for Simulating SOFC Performance and Degradation

    SciTech Connect

    Recknagle, Kurtis P.; Ryan, Emily M.; Khaleel, Mohammad A.

    2011-10-13

    This report presents a distributed electrochemistry (DEC) model capable of investigating the electrochemistry and local conditions with the SOFC MEA based on the local microstructure and multi-physics. The DEC model can calculate the global current-voltage (I-V) performance of the cell as determined by the spatially varying local conditions through the thickness of the electrodes and electrolyte. The simulation tool is able to investigate the electrochemical performance based on characteristics of the electrode microstructure, such as particle size, pore size, electrolyte and electrode phase volume fractions, and triple-phase-boundary length. It can also investigate performance as affected by fuel and oxidant gas flow distributions and other environmental/experimental conditions such as temperature and fuel gas composition. The long-term objective for the DEC modeling tool is to investigate factors that cause electrode degradation and the decay of SOFC performance which decrease longevity.

  13. Carbon deposition in CH4/CO2 operated SOFC: Simulation and experimentation studies

    NASA Astrophysics Data System (ADS)

    Girona, K.; Laurencin, J.; Fouletier, J.; Lefebvre-Joud, F.

    2012-07-01

    Due to their high operating temperatures, SOFCs can be directly fed with biogas, mainly composed of CH4 and CO2. In this work, experiments was performed with a classical Ni-YSZ cermet//YSZ//LSM cell fed either with a synthetic simulated biogas (CH4/CO2 ratio equal to 1 with 6% humidity), or with humidified H2. In both cases, the performances are found to be very similar, which confirms the ability of SOFCs to operate with internal reforming of biogas. Nevertheless, carbon formation in these operating conditions needs to be considered because of durability concerns. Thermodynamic calculations and modelling are carried out to evaluate the risk of carbon deposition depending on operating parameters. In the ternary diagram Csbnd Hsbnd O, the limits for carbon deposition are plotted, allowing the determination of “safe” operating conditions in terms of CH4 inlet flow rate and cell voltage. First experiments confirm these modelling results.

  14. Determination of interfacial adhesion strength between oxide scale and substrate for metallic SOFC interconnects

    NASA Astrophysics Data System (ADS)

    Sun, X.; Liu, W. N.; Stephens, E.; Khaleel, M. A.

    The interfacial adhesion strength between the oxide scale and the substrate is crucial to the reliability and durability of metallic interconnects in solid oxide fuel cell (SOFC) operating environments. It is necessary, therefore, to establish a methodology to quantify the interfacial adhesion strength between the oxide scale and the metallic interconnect substrate, and furthermore to design and optimize the interconnect material as well as the coating materials to meet the design life of an SOFC system. In this paper, we present an integrated experimental/analytical methodology for quantifying the interfacial adhesion strength between the oxide scale and a ferritic stainless steel interconnect. Stair-stepping indentation tests are used in conjunction with subsequent finite element analyses to predict the interfacial strength between the oxide scale and Crofer 22 APU substrate.

  15. Surface modification of alloys for improved oxidation resistance in SOFC applications

    SciTech Connect

    Alman, D.E.; Jablonski, P.D.; Kung, S.C.

    2006-11-01

    This research is aimed at improving the oxidation behavior of metallic alloys for SOFC application, by the incorporation of rare earths through surface treatments. This paper details the effect of such surface modification on the behavior of Crofer 22 APU, a ferritic steel designed specifically for SOFC application, and Type 430 stainless steel. Two pack cementation like treatments were used to incorporate Ce into the surface of the alloys. After 4000 hours of exposure at 800oC to air+3%H2O, the weight gain of Crofer 22APU samples that were Ce surface modified were less than half that of an unmodified sample, revealing the effectiveness of the treatments on enhancing oxidation resistance. For Type-430, the treatment prevented scale spalling that occurred during oxidation of the unmodified alloy.

  16. Thermal management of power sources for mobile electronic devices based on micro-SOFC

    NASA Astrophysics Data System (ADS)

    Murayama, S.; Iguchi, F.; Shimizu, M.; Yugami, H.

    2014-11-01

    Small power sources based on micro-SOFC for mobile electronic devices required two conditions, i,e, thermally compatibility and thermally self-sustain, because of high operating temperature over 300 oC. Moreover, high energy efficiency was also required. It meant that this system should be designed considering thermal management. In this study, we developed micro-SOFC packages which have three functions, thermal insulation, thermal recovery, and self-heating. Heat conduction analysis based on finite element method, and thermochemical calculation revealed that vacuum thermal insulation was effective for size reduction and gas-liquid heat exchanger could reduce the temperature of outer surface. We fabricated the package with three functions for proof of concept and evaluated. As a result, it was suggested that developed package could satisfy both two requirements with high efficiency.

  17. Development of MnCoO Coating with New Aluminizing Process for Planar SOFC Stacks

    SciTech Connect

    Choi, Jung-Pyung; Weil, K. Scott; Chou, Y. S.; Stevenson, Jeffry W.; Yang, Zhenguo

    2011-03-22

    Low-cost, chromia-forming steels find widespread use in SOFCs at operating temperatures below 800°C, because of their low thermal expansion mismatch and low cost. However, volatile Cr-containing species originating from this scale poison the cathode material in the cells and subsequently cause power degradation in the devices. To prevent this, a conductive manganese cobaltite coating has been developed. However, this coating is not compatible with forming hermetic seals between the interconnect or window frame component and ceramic cell. This coating reacts with sealing materials. Thus, a new aluminizing process has been developed for the sealing regions in these parts, as well as for other metallic stack and balance-of-plant components. From this development, the sealing performance and SOFC stack performance became very stable.

  18. Preparation of thin layer materials with macroporous microstructure for SOFC applications

    SciTech Connect

    Marrero-Lopez, D.; Ruiz-Morales, J.C.; Pena-Martinez, J.; Canales-Vazquez, J.; Nunez, P.

    2008-04-15

    A facile and versatile method using polymethyl methacrylate (PMMA) microspheres as pore formers has been developed to prepare thin layer oxide materials with controlled macroporous microstructure. Several mixed oxides with fluorite and perovskite-type structures, i.e. doped zirconia, ceria, ferrites, manganites, and NiO-YSZ composites have been prepared and characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption and mercury porosimetry. The synthesised materials are nanocrystalline and present a homogeneous pore distribution and relatively high specific surface area, which makes them interesting for SOFC and catalysis applications in the intermediate temperature range. - Graphical abstract: Thin films materials of mixed oxides with potential application in SOFC devices have been prepared with macroporous microstructure using PMMA microspheres as pore formers. Display Omitted.

  19. LaCrO{sub 3}-dispersed Cr for metallic interconnect of planar SOFC

    SciTech Connect

    Song, Rak-Hyun; Shin, Dong Ryul; Dokiya, Masayuki

    1996-12-31

    In the planar SOFC, the interconnect materials plays two roles as an electrical connection and as a gas separation plate in a cell stack. The interconnect materials must be chemically stable in reducing and oxidizing environments, and have high electronic conductivity, high thermal conductivity, matching thermal expansion with an electrolyte, high mechanical strength, good fabricability, and gas tightness. Lanthanum chromite so far has been mainly used as interconnect materials in planar SOFC. However, the ceramic materials are very weak in mechanical strength and have poor machining property as compared with metal. Also the metallic materials have high electronic conductivity and high thermal conductivity. Recently some researchers have studied metallic interconnects such as Al{sub 2}O{sub 3}/Inconel 600 cermet, Ni-20Cr coated with (LaSr)CoO{sub 3}, and Y{sub 2}O{sub 3-} or La{sub 2}O{sub 3}-dispersed Cr alloy. These alloys have still some problems because Ni-based alloys have high thermal expansion, the added Al{sub 2}O{sub 3}, Y{sub 2}O{sub 3} and La{sub 2}O{sub 3} to metals have no electronic conductivity, and the oxide formed on the surface of Cr alloy has high volatility. To solve these problems, in this study, LaCrO{sub 3}-dispersed Cr for metallic interconnect of planar SOFC was investigated. The LaCrO{sub 3}-dispersed Cr can be one candidate of metallic interconnect because LaCrO{sub 3} possesses electronic conductivity and Cr metal has relatively low thermal expansion. The content of 25 vol.% LaCrO{sub 3} Was selected on the basis of a theoretically calculated thermal expansion. The thermal expansion, electrical and oxidation properties were examined and the results were discussed as related to SOFC requirements.

  20. DETERMINATION OF ELECTROCHEMICAL PERFORMANCE, AND THERMO-MECHANICALCHEMICAL STABILITY OF SOFCS FROM DEFECT MODELING

    SciTech Connect

    Wachsman, E.D.; Duncan, K.L.; Ebrahimi, F.

    2005-01-27

    The objectives of this project were to: provide fundamental relationships between SOFC performance and operating conditions and transient (time dependent) transport properties; extend models to thermo-mechanical stability, thermo-chemical stability, and multilayer structures; incorporate microstructural effects such as grain boundaries and grain-size distribution; experimentally verify models and devise strategies to obtain relevant material constants; and assemble software package for integration into SECA failure analysis models.

  1. Evaluation of a Surface Treatment on the Performance of Stainless Steels for SOFC Interconnect Applications

    SciTech Connect

    Alman, D.E.; Holcomb, Adler, T.A.; G.R.; Wilson, R.D.; Jablonski, P.D.

    2007-04-01

    Pack cementation-like Cerium based surface treatments have been found to be effective in enhancing the oxidation resistance of ferritic steels (Crofer 22APU) for solid oxide fuel cell (SOFC) applications. The application of either a CeN- or CeO2 based surface treatment results in a decrease in weight gain by a factor of three after 4000 hours exposure to air+3%H2O at 800oC. Similar oxide scales formed on treated and untreated surfaces, with a continuous Cr-Mn outer oxide layer and a continuous inner Cr2O3 layer formed on the surface. However, the thickness of the scales, and the amount of internal oxidation were significantly reduced with the treatment, leading to the decrease in oxidation rate. This presentation will detail the influence of the treatment on the electrical properties of the interconnect. Half-cell experiments (LSM cathode sandwiched between two steel interconnects) and full SOFC button cell experiments were run with treated and untreated interconnects. Preliminary results indicate the Ce treatment can improve SOFC performance.

  2. Performance Impact Associated with Ni-Based SOFCs Fueled with Higher Hydrocarbon-Doped Coal Syngas

    NASA Astrophysics Data System (ADS)

    Hackett, Gregory A.; Gerdes, Kirk; Chen, Yun; Song, Xueyan; Zondlo, John

    2015-03-01

    Energy generation strategies demonstrating high efficiency and fuel flexibility are desirable in the contemporary energy market. When integrated with a gasification process, a solid oxide fuel cell (SOFC) can produce electricity at efficiencies exceeding 50 pct by consuming fuels such as coal, biomass, municipal solid waste, or other opportunity wastes. The synthesis gas derived from such fuel may contain trace species (including arsenic, lead, cadmium, mercury, phosphorus, sulfur, and tars) and low concentration organic species that adversely affect the SOFC performance. This work demonstrates the impact of exposure of the hydrocarbons ethylene, benzene, and naphthalene at various concentrations. The cell performance degradation rate is determined for tests exceeding 500 hours at 1073 K (800 °C). Cell performance is evaluated during operation with electrochemical impedance spectroscopy, and exposed samples are post-operationally analyzed by scanning electron microscopy/energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The short-term performance is modeled to predict performances to the desired 40,000-hours operational lifetime for SOFCs. Possible hydrocarbon interactions with the nickel anode are postulated, and acceptable hydrocarbon exposure limits are discussed.

  3. Studies on Effective Utilization of SOFC Exhaust Heat Using Thermoelectric Power Generation Technology

    NASA Astrophysics Data System (ADS)

    Terayama, Takeshi; Nagata, Susumu; Tanaka, Yohei; Momma, Akihiko; Kato, Tohru; Kunii, Masaru; Yamamoto, Atsushi

    2013-07-01

    Solid oxide fuel cells (SOFCs) are being researched around the world. In Japan, a compact SOFC system with rated alternative current (AC) power of 700 W has become available on the market, since the base load electricity demand for a standard home is said to be less than 700 W AC. To improve the generating efficiency of SOFC systems in the 700-W class, we focused on thermoelectric generation (TEG) technology, since there are a lot of temperature gradients in the system. Analysis based on simulations indicated the possibility of introducing thermoelectric generation at the air preheater, steam generator, and exhaust outlet. Among these options, incorporating a TEG heat exchanger comprising multiple CoSb3/SiGe-based TEG modules into the air preheater had potential to produce additional output of 37.5 W and an improvement in generating efficiency from 46% to 48.5%. Furthermore, by introducing thermoelectric generation at the other two locations, an increase in maximum output of more than 50 W and generating efficiency of 50% can be anticipated.

  4. Single-level optimization of a hybrid SOFC-GT power plant

    NASA Astrophysics Data System (ADS)

    Calise, F.; Dentice d'Accadia, M.; Vanoli, L.; von Spakovsky, M. R.

    The detailed synthesis/design optimization of a hybrid solid oxide fuel cell-gas turbine (SOFC-GT) power plant is presented in this paper. In the first part of the paper, the bulk-flow model used to simulate the plant is discussed. The performance of the centrifugal compressors and radial turbine is determined using maps, properly scaled in order to match the values required for mass flow rate and pressure ratio. Compact heat exchangers are simulated using Colburn and friction factor correlations. For the SOFC, the cell voltage versus current density curves (i.e. polarization curves) are generated on the basis of the Nernst potential and overvoltages. Validation of the SOFC polarization curves is accomplished with data available from Siemens Westinghouse. Both the steam-methane pre-reforming and internal reforming processes are modeled assuming the water-gas shift reaction to be equilibrium-controlled and the demethanization reactions to be kinetically controlled. Finally, a thermoeconomic model is developed by introducing capital cost functions for each plant component. The whole plant is first simulated for a fixed configuration. Then, a synthesis/design optimization of the plant is carried out using a traditional single-level approach. The results of the optimization are presented and discussed.

  5. Mitigation of Sulfur Poisoning of Ni/Zirconia SOFC Anodes by Antimony and Tin

    SciTech Connect

    Marina, Olga A.; Coyle, Christopher A.; Engelhard, Mark H.; Pederson, Larry R.

    2011-02-28

    Surface Ni/Sb and Ni/Sb alloys were found to efficiently minimize the negative effects of sulfur on the performance of Ni/zirconia anode-supported solid oxide fuel cells (SOFC). Prior to operating on fuel gas containing low concentrations of H2S, the nickel/zirconia anodes were briefly exposed to antimony or tin vapor, which only slightly affected the SOFC performance. During the subsequent exposures to 1 and 5 ppm H2S, increases in anodic polarization losses were minimal compared to those observed for the standard nickel/zirconia anodes. Post-test XPS analyses showed that Sb and Sn tended to segregate to the surface of Ni particles, and further confirmed a significant reduction of adsorbed sulfur on the Ni surface in Ni/Sn and Ni/Sb samples compared to the Ni. The effect may be the result of weaker sulfur adsorption on bimetallic surfaces, adsorption site competition between sulfur and Sb or Sn on Ni, or other factors. The use of dilute binary alloys of Ni-Sb or Ni-Sn in the place of Ni, or brief exposure to Sb or Sn vapor, may be effective means to counteract the effects of sulfur poisoning in SOFC anodes and Ni catalysts. Other advantages, including suppression of coking or tailoring the anode composition for the internal reforming, are also expected.

  6. EFFECT OF FUEL IMPURITY ON STRUCTURAL INTEGRITY OF Ni-YSZ ANODE OF SOFCs

    SciTech Connect

    Liu, Wenning N.; Sun, Xin; Marina, Olga A.; Pederson, Larry R.; Khaleel, Mohammad A.

    2011-01-01

    Electricity production through the integration of coal gasification with solid oxide fuel cells (SOFCs) may potentially be an efficient technique for clean energy generation. However, multiple minor and trace components are naturally present in coals. These impurities in coal gas not only degrade the electrochemical performance of Ni-YSZ anode used in SOFCs, but also severely endanger the structural integrity of the Ni-YSZ anode. In this paper, effect of the trace impurity of the coal syngases on the mechanical degradation of Ni-YSZ anode was studied by using an integrated experimental/modeling approach. Phosphorus is taken as an example of impurity. Anode-support button cell was used to experimentally explore the migration of phosphorous impurity in the Ni-YSZ anode of SOFCs. X-ray mapping was used to show elemental distributions and new phase formation. The subsequent finite element stress analyses were conducted using the actual microstructure of the anode to illustrate the degradation mechanism. It was found that volume expansion induced by the Ni phase change produces high stress level such that local failure of the Ni-YSZ anode is possible under the operating conditions

  7. EFFECT OF FUEL IMPURITY ON STRUCTURAL INTEGRITY OF Ni-YSZ ANODE OF SOFCS

    SciTech Connect

    Liu, Wenning N.; Sun, Xin; Marina, Olga A.; Pederson, Larry R.; Khaleel, Mohammad A.

    2010-12-31

    Electricity production through the integration of coal gasification with solid oxide fuel cells (SOFCs) may potentially be an efficient technique for clean energy generation. However, multiple minor and trace components are naturally present in coals. These impurities in coal gas not only degrade the electrochemical performance of Ni-YSZ anode used in SOFCs, but also severely endanger the structural integrity of the Ni-YSZ anode. In this paper, effect of the trace impurity of the coal syngases on the mechanical degradation of Ni-YSZ anode was studied by using an integrated experimental/modeling approach. Phosphorus is taken as an example of impurity. Anode-support button cell was used to experimentally explore the migration of phosphorous impurity in the Ni-YSZ anode of SOFCs. X-ray mapping was used to show elemental distributions and new phase formation. The subsequent finite element stress analyses were conducted using the actual microstructure of the anode to illustrate the degradation mechanism. It was found that volume expansion induced by the Ni phase change produces high stress level such that local failure of the Ni-YSZ anode is possible under the operating conditions

  8. Refinement of numerical models and parametric study of SOFC stack performance

    NASA Astrophysics Data System (ADS)

    Burt, Andrew C.

    The presence of multiple air and fuel channels per fuel cell and the need to combine many cells in series result in complex steady-state temperature distributions within Solid Oxide Fuel Cell (SOFC) stacks. Flow distribution in these channels, when non-uniform, has a significant effect on cell and stack performance. Large SOFC stacks are very difficult to model using full 3-D CFD codes because of the resource requirements needed to solve for the many scales involved. Studies have shown that implementations based on Reduced Order Methods (ROM), if calibrated appropriately, can provide simulations of stacks consisting of more than 20 cells with reasonable computational effort. A pseudo 2-D SOFC stack model capable of studying co-flow and counter-flow cell geometries was developed by solving multiple 1-D SOFC single cell models in parallel on a Beowulf cluster. In order to study cross-flow geometries a novel Multi-Component Multi-Physics (MCMP) scheme was instantiated to produce a Reduced Order 3-D Fuel Cell Model. A C++ implementation of the MCMP scheme developed in this study utilized geometry, control volume, component, and model structures allowing each physical model to be solved only for those components for which it is relevant. Channel flow dynamics were solved using a 1-D flow model to reduce computational effort. A parametric study was conducted to study the influence of mass flow distribution, radiation, and stack size on fuel cell stack performance. Using the pseudo 2-D planar SOFC stack model with stacks of various sizes from 2 to 40 cells it was shown that, with adiabatic wall conditions, the asymmetry of the individual cell can produce a temperature distribution where high and low temperatures are found in the top and bottom cells, respectively. Heat transfer mechanisms such as radiation were found to affect the reduction of the temperature gradient near the top and bottom cell. Results from the reduced order 3-D fuel cell model showed that greater

  9. Approaches to mitigate metal catalyst deactivation in solid oxide fuel cell (SOFC) fuel electrodes

    NASA Astrophysics Data System (ADS)

    Adijanto, Lawrence

    While Ni/YSZ cermets have been used successfully in SOFCs, they also have several limitations, thus motivating the use of highly conductive ceramics to replace the Ni components in SOFC anodes. Ceramic electrodes are promising for use in SOFC anodes because they are expected to be less susceptible to sintering and coking, be redox stable, and be more tolerant of impurities like sulfur. In this thesis, for catalytic studies, the infiltration procedure has been used to form composites which have greatly simplified the search for the best ceramics for anode applications. In the development of ceramic fuel electrodes for SOFC, high performance can only be achieved when a transition metal catalyst is added. Because of the high operating temperatures, deactivation of the metal catalyst by sintering and/or coking is a severe problem. In this thesis, two approaches aimed at mitigating metal catalyst deactivation which was achieved by: 1) designing a catalyst that is resistant to coking and sintering and 2) developing a new method for catalyst deposition, will be presented. The first approach involved synthesizing a self-regenerating, "smart" catalyst, in which Co, Cu, or Ni were inserted into the B-site of a perovskite oxide under oxidizing conditions and then brought back to the surface under reducing conditions. This restores lost surface area of sintered metal particles through an oxidation/reduction cycle. Results will be shown for each of the metals, as well as for Cu-Co mixed metal systems, which are found to exhibit good tolerance to carbon deposition and interesting catalytic properties. The second strategy involves depositing novel Pd CeO2 core-shell nanostructure catalysts onto a substrate surface which had been chemically modified to anchor the nanoparticles. The catalyst deposited onto the chemically modified, hydrophobic surface is shown to be uniform and well dispersed, and exhibit excellent thermal stability to temperatures as high as 1373 K. Similar metal

  10. High performance single step co-fired solid oxide fuel cells (SOFC): Polarization measurements and analysis

    NASA Astrophysics Data System (ADS)

    Yoon, Kyung Joong

    At present, one of the major obstacles for the commercialization of solid oxide fuel cell (SOFC) power systems is their high manufacturing costs expressed in terms of SOFC system cost per unit power ($/kW). In this work, anode-supported planar SOFCs were fabricated by a cost-competitive single step co-firing process. The cells were comprised of a porous Ni + yittria-stabilized zirconia (YSZ) anode support, a porous-fine-grained Ni + YSZ anode active layer for some experiments, a dense YSZ electrolyte, a porous-fine-grained Ca-doped LaMnO3 (LCM) + YSZ cathode active layer, and a porous LCM cathode current collector layer. The fabrication process involved tape casting or high shear compaction (HSC) of the anode support followed by screen printing of the remaining component layers. The cells were then co-fired at 1300˜1340°C for 2 hours. The performance of the cell fabricated with the tape casting anode was improved by minimizing various polarization losses through experimental and theoretical modeling approaches, and the maximum power density of 1.5 W/cm 2 was obtained at 800°C with humidified hydrogen (3% H2O) and air. The cells were also tested with various compositions of humidified hydrogen (3˜70% H2O) to simulate the effect of practical fuel utilization on the cell performance. Based on these measurements, an analytical model describing anodic reactions was developed to understand reaction kinetics and rate limiting steps. The cell performance at high fuel utilization was significantly improved by increasing the number of the reaction sites near the anode-electrolyte interface. For anode substrate fabrication, the HSC process offers many advantages such as low fabrication costs, high production throughput, and good control of shrinkage and thickness over the conventional tape casting process. HSC process was successfully employed in single step co-firing process, and SOFCs fabricated with HSC anodes showed adequate performance both at low and high fuel

  11. Techno-Economic Feasibility of Highly Efficient Cost-Effective Thermoelectric-SOFC Hybrid Power Generation Systems

    SciTech Connect

    Jifeng Zhang; Jean Yamanis

    2007-09-30

    Solid oxide fuel cell (SOFC) systems have the potential to generate exhaust gas streams of high temperature, ranging from 400 to 800 C. These high temperature gas streams can be used for additional power generation with bottoming cycle technologies to achieve higher system power efficiency. One of the potential candidate bottoming cycles is power generation by means of thermoelectric (TE) devices, which have the inherent advantages of low noise, low maintenance and long life. This study was to analyze the feasibility of combining coal gas based SOFC and TE through system performance and cost techno-economic modeling in the context of multi-MW power plants, with 200 kW SOFC-TE module as building blocks. System and component concepts were generated for combining SOFC and TE covering electro-thermo-chemical system integration, power conditioning system (PCS) and component designs. SOFC cost and performance models previously developed at United Technologies Research Center were modified and used in overall system analysis. The TE model was validated and provided by BSST. The optimum system in terms of energy conversion efficiency was found to be a pressurized SOFC-TE, with system efficiency of 65.3% and cost of $390/kW of manufacturing cost. The pressurization ratio was approximately 4 and the assumed ZT of the TE was 2.5. System and component specifications were generated based on the modeling study. The major technology and cost barriers for maturing the system include pressurized SOFC stack using coal gas, the high temperature recycle blowers, and system control design. Finally, a 4-step development roadmap is proposed for future technology development, the first step being a 1 kW proof-of-concept demonstration unit.

  12. Mechanisms of albumin uptake by proximal tubular cells.

    PubMed

    Brunskill, N

    2001-01-01

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

  13. The glomerulo-tubular junction: a target in renal diseases.

    PubMed

    Lindop, G B M; Gibson, I W; Downie, T T; Vass, D; Cohen, E P

    2002-05-01

    Both global and segmental glomerulopathies may damage specific areas of the renal glomerulus. Diseases associated with glomerular hyperperfusion cause lesions at the vascular pole, while diseases associated with proteinuria often damage the tubular pole. Atubular glomeruli are now known to be plentiful in a variety of common renal diseases. These glomeruli are disconnected from their tubule at the tubular pole and therefore cannot participate in the production of urine. It is widely believed that the disconnection is a result of external compression by periglomerular fibrosis. However, the variable anatomy and cell populations within both the glomerulus and the beginning of the proximal tubule at the glomerulo-tubular junction may also have important roles to play in the response to damage at this sensitive site of the nephron.

  14. Extremely strong tubular stacking of aromatic oligoamide macrocycles

    SciTech Connect

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

    2014-09-16

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

  15. Extremely strong tubular stacking of aromatic oligoamide macrocycles

    DOE PAGES

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

    2014-09-16

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

  16. Mathematical models for tubular structures in the family of Papovaviridae.

    PubMed

    Twarock, R

    2005-09-01

    An important part of a virus is its protein shell, called the viral capsid, that protects the viral genome. While the viral capsids of viruses in the family of Papovaviridae are usually spherical, their protein building blocks are known to assemble also as tubular structures [Kiselev, N.A., Klug, A., 1969. J. Mol. Biol. 40, 155]. In Twarock [2004. J. Theor. Biol. 226, 477] Viral Tiling Theory has been introduced for the structural description of the protein stoichiometry of the spherical capsids in this family. This approach is extended here to the tubular case and is used to classify the surface lattices of tubular structures in the family of Papovaviridae. The predictions of the theory are compared with the experimental results in Kiselev and Klug [1969. J. Mol. Biol. 40, 155].

  17. 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

  18. Extremely strong tubular stacking of aromatic oligoamide macrocycles

    DOE PAGES

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

    2015-01-01

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

  19. 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.

  20. Refined computational modeling of SOFCs degradation due to trace impurities in coal syngas

    NASA Astrophysics Data System (ADS)

    Sezer, Hayri

    The Solid Oxide Fuel Cell (SOFC) is a good alternative for clean and efficient power generation. These cells can be operated directly on a wide variety of fuels including biogas, hydrocarbon fuels and synthesized coal gas (syngas), which is a promising avenue for utilization of coal with much less environmental impact. One of the challenges in this technology is poisoning of SOFC anodes by trace impurities contained in coal syngas. One such impurity, phosphine is known to cause catastrophic failure of SOFC anode even at <10ppm concentrations. Fuel impurity degradation patterns can vary by different operating conditions such as humidity, applied current, temperature and anode thickness. In the present study, more detailed models are developed to predict the typical degradation behaviors observed in SOFC anode due to phosphine by extension of an in-house one-dimensional computational code. This model is first used to predict the effect of steam concentration on phosphine induced degradation in anode supported SOFCs. The model is refined based on the experimental observation, which indicate that the phosphine degradation is less severe in the absence of steam. Simulations results showed good agreement with experimental data. Then, a sensitivity analysis, using dual numbers automatic differentiation (DNAD) is performed to investigate the influence of empirical model parameters on model outputs, electrical potential, ohmic and polarization losses. Further, the refined one-dimensional model is extended to a three-dimensional model to study the phosphine induced performance degradation in relatively large planar cells operating on hydrogen fuel. The empirical model parameters are calibrated using button cell experiments and sensitivity analysis as a guide. These parameters are then used in planar cell simulations. The results from the three dimensional model show that the contaminant coverage of nickel and fuel distribution inside the anode is highly non-uniform. These

  1. High temperature tubular solid oxide fuel cell development

    SciTech Connect

    Ray, E.R.

    1992-09-01

    Important to the development commercialization of any new technology is a field test program. This is a mutually beneficial program for both the developer and the prospective user. The developer is able to acquire valuable field operating experience that is not available in a laboratory while the user has the opportunity to become familiar with the new technology and gains a working knowledge of it through hands-on experience. Westinghouse, recognizing these benefits, initiated a program in 1986 by supplying a 400 W SOFC generator to Tennessee Valley Authority. This generator operated for approximately 1,760 hours and was constructed of twenty-four 30 cm thick-wall PST cells. In 1987, three, 3 kW SOFC generators were installed and operated at the facilities of the Tokyo Gas Company and the Osaka Gas Company. At Osaka Gas, two generators were used. First a training generator, operated for 2900 hours before it was replaced on a preplanned schedule with the second generator. The second generator operated for 3,600 hours. Tokyo Gas generator was operated for 4,900 hours. These generators had a 98% availability and measured NO{sub x} levels of less than 1.3 ppM. The 3 kW SOFC generators were constructed of 144 36 cm thick-wall PST cells. The 3 kW generators, as was the TVA generator, were fueled with hydrogen and carbon monoxide. The next major milestone in the field unit program was reached in early 1992 with the delivery to The UTILITIES, a consortium of the Kansai Electric Power company, the Tokyo Gas Company, and the Osaka Gas Company, of a natural gas fueled all electric SOFC system. This system is rated at a nominal 25 kW dc with a peak capacity of 40 kW dc. The NO{sub x} was measured at <0.3 ppM (corrected to 15% oxygen). The system consists of 1152 cells (thin-wall PST) of 50 cm active length, manufactured at the PPMF. Cells are contained in two independently controlled and operated generators. 2,300 hours of stable operation has been obtained on the first unit.

  2. High temperature tubular solid oxide fuel cell development

    SciTech Connect

    Ray, E.R.

    1992-01-01

    Important to the development commercialization of any new technology is a field test program. This is a mutually beneficial program for both the developer and the prospective user. The developer is able to acquire valuable field operating experience that is not available in a laboratory while the user has the opportunity to become familiar with the new technology and gains a working knowledge of it through hands-on experience. Westinghouse, recognizing these benefits, initiated a program in 1986 by supplying a 400 W SOFC generator to Tennessee Valley Authority. This generator operated for approximately 1,760 hours and was constructed of twenty-four 30 cm thick-wall PST cells. In 1987, three, 3 kW SOFC generators were installed and operated at the facilities of the Tokyo Gas Company and the Osaka Gas Company. At Osaka Gas, two generators were used. First a training generator, operated for 2900 hours before it was replaced on a preplanned schedule with the second generator. The second generator operated for 3,600 hours. Tokyo Gas generator was operated for 4,900 hours. These generators had a 98% availability and measured NO{sub x} levels of less than 1.3 ppM. The 3 kW SOFC generators were constructed of 144 36 cm thick-wall PST cells. The 3 kW generators, as was the TVA generator, were fueled with hydrogen and carbon monoxide. The next major milestone in the field unit program was reached in early 1992 with the delivery to The UTILITIES, a consortium of the Kansai Electric Power company, the Tokyo Gas Company, and the Osaka Gas Company, of a natural gas fueled all electric SOFC system. This system is rated at a nominal 25 kW dc with a peak capacity of 40 kW dc. The NO{sub x} was measured at <0.3 ppM (corrected to 15% oxygen). The system consists of 1152 cells (thin-wall PST) of 50 cm active length, manufactured at the PPMF. Cells are contained in two independently controlled and operated generators. 2,300 hours of stable operation has been obtained on the first unit.

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

    NASA Technical Reports Server (NTRS)

    Warden, Robert M.

    1995-01-01

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

  4. The Strength of Shell and Tubular Spar Wings

    NASA Technical Reports Server (NTRS)

    Ebner, H

    1940-01-01

    The report is a survey of the strength problems arising on shell and tubular spar wings. The treatment of the shell wing strength is primarily confined to those questions which concern the shell wing only; those pertaining to both shell wing and shell body together have already been treated in TM 838. The discussion of stress condition and compressive strength of shell wings and tubular spar wings is prefaced by several considerations concerning the spar and shell design of metal wings from the point of view of strength.

  5. Hot fire test results of subscale tubular combustion chambers

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  6. Communicating Tubular Esophageal Duplication Combined with Bronchoesophageal Fistula

    PubMed Central

    Kim, Ju Hwan; Kwon, Chang-Il; Rho, Ji Young; Han, Sang Woo; Kim, Ji Su; Shin, Suk Pyo; Song, Ga Won; Hahm, Ki Baik

    2016-01-01

    Esophageal duplication (ED) is rarely diagnosed in adults and is usually asymptomatic. Especially, ED that is connected to the esophagus through a tubular communication and combined with bronchoesophageal fistula (BEF) is extremely rare and has never been reported in the English literature. This condition is very difficult to diagnose. Although some combinations of several modalities, such as upper gastrointestinal endoscopy, esophagography, computed tomography, magnetic resonance imaging, and endoscopic ultrasonography, can be used for the diagnosis, the results might be inconclusive. Here, we report on a patient with communicating tubular ED that was incidentally diagnosed on the basis of endoscopy and esophagography during the postoperational evaluation of BEF. PMID:26855929

  7. Renal histology and immunopathology in distal renal tubular acidosis.

    PubMed

    Feest, T G; Lockwood, C M; Morley, A R; Uff, J S

    1978-11-01

    Renal biospy studies are reported from 10 patients with distal renal tubular acidosis (DRTA). On the biopsies from 6 patients who had associated immunological abnormalities immunofluorescent studies for immunoglobulins, complement, and fibrin were performed. Interstitial cellular infiltration and fibrosis were common findings in patients with and without immunological abnormalities, and were usually associated with nephrocalcinosis and/or recurrent urinary infection. No immune deposits were demonstrated in association with the renal tubules. This study shows that DRTA in immunologically abnormal patients is not caused by tubular deposition of antibody or immune complexes. The possibility of cell mediated immune damage is discussed.

  8. Numerical analysis of electrochemical characteristics and heat/species transport for planar porous-electrode-supported SOFC

    NASA Astrophysics Data System (ADS)

    Wang, Yuzhang; Yoshiba, Fumihiko; Watanabe, Takao; Weng, Shilie

    In this work, a fully three-dimensional mathematical model for planar porous-electrode-supported (PES) solid oxide fuel cell (SOFC) has been constructed to simulate the steady state electrochemical characteristics and multi-species/heat transport. The variation of chemical species concentrations, temperature, potential, current and current density for two types of PES-SOFC developed by central research institute of electric power industry (CRIEPI) of Japan are studied in the co-flow pattern. In the numerical computation, the governing equations for continuity, momentum, mass, energy and electrical charge conservation are solved simultaneously using the finite volume method. Activation, ohmic, and concentration polarizations are considered as the main sources of irreversibility. The Butler-Volmer equation, Ohm's law, and Darcy's gas model with constant porosity and permeability are used to determine the polarization over-potential, respectively. The output voltages measured in experiments and calculated using the above models agree well. For the cell using the same material and manufacturing process, the results show the type-II PES-SOFC is with better performance. However, the electrolyte of type-II PES-SOFC should be with higher maximum ionic conductivity. Furthermore, these results will be used to evaluate the overall performance of a PES-SOFC stack, and to significantly help optimize their design and operation in practical applications.

  9. Balance of plant for SOFC experiences with the planning, engineering, construction and testing of a 10 kW planar SOFC pilot plant

    SciTech Connect

    Klov, K.; Sundal, P.; Monsen, T.; Vik, A.

    1996-12-31

    The Statoil Solide Oxide Fuel Cell Research Program was started in January 1991. Some results from this Program were presented to the 1994 Fuel Cell Seminar in San Diego. The final technical milestone for the program was to design, engineer, construct and test a 10 kW pilot plant. From the very beginning, the importance of coordination and integration in the development of components, subsystems and systems, combined with basic research on cell and stack performance, were established as the guidelines for the program. In this way the progress towards the final goal was not a matter of making the best individual cell, the best stack or a superior balance of plant, but to build an efficient, reliable and operative pilot plant system, and thus make a further step towards a verification of commercial SOFC system technology.

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

    ERIC Educational Resources Information Center

    Asfour, Abdul-Fattah A.

    1985-01-01

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

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

    PubMed

    Fiseha, Temesgen; Tamir, Zemenu

    2016-01-01

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

  12. Changes at the glomerulo-tubular junction in renal transplants.

    PubMed

    Lee, S J; Howie, A J

    1988-12-01

    We studied by microscopy 377 biopsies, nephrectomies, and necropsy kidneys from 123 human renal transplants. We discovered two common abnormalities of the renal corpuscle, both affecting the glomerulo-tubular junction. Adhesion of the tip of the glomerular tuft to the origin of the tubule, as reported in various non-transplant glomerulopathies, was seen in 197 specimens (52 per cent). This change was common in material showing acute or chronic vascular rejection and glomerulopathy, and was almost universal in transplants that had been in place for over 1 year. Another change at the glomerulo-tubular junction, not previously highlighted, consisted of an infiltrate of lymphocytes or neutrophil polymorphs into the epithelium at the tubular origin. This change was seen in 145 specimens (38 per cent) and was associated with cellular rejection and ascending infection. These changes are of importance because they show two responses of the kidney to injury that involve the glomerulo-tubular junction and thus suggest that this part of the kidney has some specific properties that have been largely neglected up to now.

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

    PubMed Central

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

    2013-01-01

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

  14. The establishment of radiation regimes in tubular collectors

    NASA Astrophysics Data System (ADS)

    Amanov, Ch. A.

    Methods of calculating the radiant flux density of tubular collectors are developed, showing that solutions are possible for a day, a month, or a season through computer algorithms. Also treated is the effective cross section of a collector in the absence of shading.

  15. 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.

  16. Urinary Markers of Tubular Injury in Early Diabetic Nephropathy

    PubMed Central

    Fiseha, Temesgen; Tamir, Zemenu

    2016-01-01

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

  17. 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

  18. 49 CFR 230.55 - Tubular type water and lubricator glasses and shields.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Tubular type water and lubricator glasses and... STANDARDS Boilers and Appurtenances Water Glasses and Gauge Cocks § 230.55 Tubular type water and lubricator glasses and shields. (a) Water glasses. Tubular type water glasses shall be renewed at each 92 service...

  19. 49 CFR 230.55 - Tubular type water and lubricator glasses and shields.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Tubular type water and lubricator glasses and... STANDARDS Boilers and Appurtenances Water Glasses and Gauge Cocks § 230.55 Tubular type water and lubricator glasses and shields. (a) Water glasses. Tubular type water glasses shall be renewed at each 92 service...

  20. 49 CFR 230.55 - Tubular type water and lubricator glasses and shields.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Tubular type water and lubricator glasses and... STANDARDS Boilers and Appurtenances Water Glasses and Gauge Cocks § 230.55 Tubular type water and lubricator glasses and shields. (a) Water glasses. Tubular type water glasses shall be renewed at each 92 service...

  1. 49 CFR 230.55 - Tubular type water and lubricator glasses and shields.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Tubular type water and lubricator glasses and... STANDARDS Boilers and Appurtenances Water Glasses and Gauge Cocks § 230.55 Tubular type water and lubricator glasses and shields. (a) Water glasses. Tubular type water glasses shall be renewed at each 92 service...

  2. 49 CFR 230.55 - Tubular type water and lubricator glasses and shields.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Tubular type water and lubricator glasses and... STANDARDS Boilers and Appurtenances Water Glasses and Gauge Cocks § 230.55 Tubular type water and lubricator glasses and shields. (a) Water glasses. Tubular type water glasses shall be renewed at each 92 service...

  3. 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

  4. Investigation of AISI 441 Ferritic Stainless Steel and Development of Spinel Coatings for SOFC Interconnect Applications

    SciTech Connect

    Yang, Zhenguo; Xia, Guanguang; Wang, Chong M.; Nie, Zimin; Templeton, Joshua D.; Singh, Prabhakar; Stevenson, Jeffry W.

    2008-05-30

    As part of an effort to develop cost-effective ferritic stainless steel-based interconnects for solid oxide fuel cell (SOFC) stacks, both bare and spinel coated AISI 441 were studied in terms of metallurgical characteristics, oxidation behavior, and electrical performance. The conventional melt metallurgy used for the bulk alloy fabrication leads to significant processing cost reduction and the alloy chemistry with the presence of minor alloying additions of Nb and Ti facilitate the strengthening by precipitation and formation of Laves phase both inside grains and along grain boundaries during exposure in the intermediate SOFC operating temperature range. The Laves phase formed along the grain boundaries also ties up Si and prevents the formation of an insulating silica layer at the scale/metal interface during prolonged exposure. The substantial increase in ASR during long term oxidation due to oxide scale growth suggested the need for a conductive protection layer, which could also minimize Cr evaporation. In particular, Mn1.5Co1.5O4 based surface coatings on planar coupons drastically improved the electrical performance of the 441, yielding stable ASR values at 800ºC for over 5,000 hours. Ce-modified spinel coatings retained the advantages of the unmodified spinel coatings, and also appeared to alter the scale growth behavior beneath the coating, leading to a more adherent scale. The spinel protection layers appeared also to improve the surface stability of 441 against the anomalous oxidation that has been observed for ferritic stainless steels exposed to dual atmosphere conditions similar to SOFC interconnect environments. Hence, it is anticipated that, compared to unmodified spinel coatings, the Ce-modified coatings may lead to superior structural stability and electrical performance.

  5. A global thermo-electrochemical model for SOFC systems design and engineering

    NASA Astrophysics Data System (ADS)

    Petruzzi, L.; Cocchi, S.; Fineschi, F.

    At BMW AG in Munich high-temperature solid oxide fuel cells (SOFCs) are being developed as an auxiliary power unit (APU) for high-class car conveniences. Their design requires simulation of their thermo-electrochemical behaviour in all the conditions that may occur during operation (i.e. heat-up to about 600 °C, start-up to operating temperature, energy-delivering and cool-down). A global thermo-electrochemical model was developed for the whole system and a three-dimensional geometry code was performed using MATLAB programming language. The problems in developing SOFCs are now so many and so different that a very flexible code is necessary. Thus, the code was not only designed in order to simulate each of the operating conditions, but also to test different stack configurations, materials, etc. In every event, the code produces a time-dependent profile of temperatures, currents, electrical and thermal power density, gases concentrations for the whole system. The heat-up and start-up simulations allow: (1) to evaluate the time the cell stack needs to reach operating temperature from an initial temperature distribution, (2) to check the steepest temperature gradients occurring in the ceramic layers (which result in material stresses) and (3) to obtain important information about the pre-operating strategy. Simulation of energy-delivering gives a detailed profile of the temperatures, currents, power density, and allows to define the guidelines in system-controlling. Simulation of cooling-down gives important advises about insulation designing. The aim of this work is to build up a tool to clearly individuate the best designing criteria and operating strategy during the development and the engineering of a SOFC system.

  6. Effect of ionic conductivity of zirconia electrolytes on polarization properties of various electrodes in SOFC

    SciTech Connect

    Watanabe, Masahiro; Uchida, Hiroyuki; Yoshida, Manabu

    1996-12-31

    Solid oxide fuel cells (SOFCs) have been intensively investigated because, in principle, their energy conversion efficiency is fairly high. Lowering the operating temperature of SOFCs from 1000{degrees}C to around 800{degrees}C is desirable for reducing serious problems such as physical and chemical degradation of the constructing materials. The object of a series of the studies is to find a clue for achieving higher electrode performances at a low operating temperature than those of the present level. Although the polarization loss at electrodes can be reduced by using mixed-conducting ceria electrolytes, or introducing the mixed-conducting (reduced zirconia or ceria) laver on the conventional zirconia electrolyte surface, no reports are available on the effect of such an ionic conductivity of electrolytes on electrode polarizations. High ionic conductivity of the electrolyte, of course, reduces the ohmic loss. However, we have found that the IR-free polarization of a platinum anode attached to zirconia electrolytes is greatly influenced by the ionic conductivity, {sigma}{sub ion}, of the electrolytes used. The higher the {sigma}{sub ion}, the higher the exchange current density, j{sub 0}, for the Pt anode in H{sub 2} at 800 {approximately} 1000{degrees}C. It was indicated that the H{sub 2} oxidation reaction rate was controlled by the supply rate of oxide ions through the Pt/zirconia interface which is proportional to the {sigma}{sub ion}. Recently, we have proposed a new concept of the catalyzed-reaction layers which realizes both high-performances of anodes and cathodes for medium-temperature operating SOFCs. We present the interesting dependence of the polarization properties of various electrodes (the SDC anodes with and without Ru microcatalysts, Pt cathode, La(Sr)MnO{sub 3} cathodes with and without Pt microcatalysts) on the {sigma}{sub ion} of various zirconia electrolytes at 800 {approximately} 1000{degrees}C.

  7. Modeling of On-Cell Reforming Reaction for Planar SOFC Stacks

    SciTech Connect

    Yang, Choongmo; Lim, Hyung-Tae; Hwang, Soon Cheol; Kim, Dohyung; Lai, Canhai; Koeppel, Brian J.; Recknagle, Kurtis P.; Khaleel, Mohammad A.

    2011-05-30

    Planar Solid Oxide Fuel Cell (SOFC) stack is known to suffer thermal problem from high stack temperature during operation to generate high current. On-Cell Reforming (OCR) phenomenon is often used to reduce stack temperature by an endothermic reaction of steam-methane reforming process. RIST conducted single-cell experiment to validate modeling tool to simulate OCR performance including temperature measurement. 2D modeling is used to check reforming rate during OCR using temperature measurement data, and 3D modeling is used to check overall thermal performance including furnace boundary conditions.

  8. Preparation of thin layer materials with macroporous microstructure for SOFC applications

    NASA Astrophysics Data System (ADS)

    Marrero-López, D.; Ruiz-Morales, J. C.; Peña-Martínez, J.; Canales-Vázquez, J.; Núñez, P.

    2008-04-01

    A facile and versatile method using polymethyl methacrylate (PMMA) microspheres as pore formers has been developed to prepare thin layer oxide materials with controlled macroporous microstructure. Several mixed oxides with fluorite and perovskite-type structures, i.e. doped zirconia, ceria, ferrites, manganites, and NiO-YSZ composites have been prepared and characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption and mercury porosimetry. The synthesised materials are nanocrystalline and present a homogeneous pore distribution and relatively high specific surface area, which makes them interesting for SOFC and catalysis applications in the intermediate temperature range.

  9. Optimization of manifold design for 1 kW-class flat-tubular solid oxide fuel cell stack operating on reformed natural gas

    NASA Astrophysics Data System (ADS)

    Rashid, Kashif; Dong, Sang Keun; Khan, Rashid Ali; Park, Seung Hwan

    2016-09-01

    This study focuses on optimizing the manifold design for a 1 kW-class flat-tubular solid oxide fuel cell stack by performing extensive three-dimensional numerical simulations on numerous manifold designs. The stack flow uniformity and the standard flow deviation indexes are implemented to characterize the flow distributions in the stack and among the channels of FT-SOFC's, respectively. The results of the CFD calculations demonstrate that the remodeled manifold without diffuser inlets and 6 mm diffuser front is the best among investigated designs with uniformity index of 0.996 and maximum standard flow deviation of 0.423%. To understand the effect of manifold design on the performance of stack, both generic and developed manifold designs are investigated by applying electrochemical and internal reforming reactions modeling. The simulation results of the stack with generic manifold are validated using experimental data and then validated models are adopted to simulate the stack with the developed manifold design. The results reveal that the stack with developed manifold design achieves more uniform distribution of species, temperature, and current density with comparatively lower system pressure drop. In addition, the results also showed ∼8% increase in the maximum output power due to the implementation of uniform fuel velocity distributions in the cells.

  10. Impact of cell design and operating conditions on the performances of SOFC fuelled with methane

    NASA Astrophysics Data System (ADS)

    Laurencin, J.; Lefebvre-Joud, F.; Delette, G.

    An in-house-model has been developed to study the thermal and electrochemical behaviour of a planar SOFC fed directly with methane and incorporated in a boiler. The usual Ni-YSZ cermet has been considered for the anode material. It has been found that methane reforming into hydrogen occurs only at the cell inlet in a limited depth within the anode. A sensitivity analysis has allowed establishing that anode thicknesses higher than ∼400-500 μm are required to achieve both the optimal methane conversion and electrochemical performances. The direct internal reforming (DIR) mechanisms and the impact of operating conditions on temperature gradients and SOFC electrical efficiencies have been investigated considering the anode supported cell configuration. It has been shown that the temperature gradient is minimised in the autothermal mode of cell operation. Thermal equilibrium in the stack has been found to be strongly dependent on radiative heat losses with the stack envelope. Electrochemical performance and cell temperature maps have been established as a function of methane flow rates and cell voltages.

  11. Analyses of Large Coal-Based SOFCs for High Power Stack Block Development

    SciTech Connect

    Recknagle, Kurtis P; Koeppel, Brian J

    2010-10-01

    This report summarizes the numerical modeling and analytical efforts for SOFC stack development performed for the coal-based SOFC program. The stack modeling activities began in 2004, but this report focuses on the most relevant results obtained since August 2008. This includes the latter half of Phase-I and all of Phase-II activities under technical guidance of VPS and FCE. The models developed to predict the thermal-flow-electrochemical behaviors and thermal-mechanical responses of generic planar stacks and towers are described. The effects of cell geometry, fuel gas composition, on-cell reforming, operating conditions, cell performance, seal leak, voltage degradation, boundary conditions, and stack height are studied. The modeling activities to evaluate and achieve technical targets for large stack blocks are described, and results from the latest thermal-fluid-electrochemical and structural models are summarized. Modeling results for stack modifications such as scale-up and component thickness reduction to realize cost reduction are presented. Supporting modeling activities in the areas of cell fabrication and loss of contact are also described.

  12. Deposition and Evaluation of Protective PVD Coatings on Ferritic Stainless Steel SOFC Interconnects

    SciTech Connect

    Gorokhovsky, Vladimir I.; Gannon, Paul; Deibert, Max; Smith, Richard J.; Kayani, Asghar N.; Kopczyk, M.; Van Vorous, D.; Yang, Z Gary; Stevenson, Jeffry W.; Visco, s.; jacobson, c.; Kurokawa, H.; Sofie, Stephen W.

    2006-09-21

    Reduced operating temperatures (600-800°C) of Solid Oxide Fuel Cells (SOFCs) may enable the use of inexpensive ferritic steels as interconnects. Due to the demanding SOFC interconnect operating environment, protective coatings are gaining attention to increase longterm stability. In this study, large area filtered arc deposition (LAFAD) and hybrid filtered arc assisted electron beam physical vapor deposition (FA-EBPVD) technologies were used for deposition of two-segment coatings with Cr-Co-Al-O-N based sublayer and Mn-Co-O top layer. Coatings were deposited on ferritic steel and subsequently annealed in air for various time intervals. Surface oxidation was investigated using RBS, SEM and EDS analyses. Cr volatilization was evaluated using a transpiration apparatus and ICP-MS analysis of the resultant condensate. Electrical conductivity (Area Specific Resistance) was studied as a function of time using the four-point technique with Ag electrodes. The oxidation behavior, Cr volatilization rate, and electrical conductivity of the coated and uncoated samples are reported. Transport mechanisms for various oxidizing species and coating diffusion barrier properties are discussed.

  13. Development and Application of HVOF Sprayed Spinel Protective Coating for SOFC Interconnects

    NASA Astrophysics Data System (ADS)

    Thomann, O.; Pihlatie, M.; Rautanen, M.; Himanen, O.; Lagerbom, J.; Mäkinen, M.; Varis, T.; Suhonen, T.; Kiviaho, J.

    2013-06-01

    Protective coatings are needed for metallic interconnects used in solid oxide fuel cell (SOFC) stacks to prevent excessive high-temperature oxidation and evaporation of chromium species. These phenomena affect the lifetime of the stacks by increasing the area-specific resistance (ASR) and poisoning of the cathode. Protective MnCo2O4 and MnCo1.8Fe0.2O4 coatings were applied on ferritic steel interconnect material (Crofer 22 APU) by high velocity oxy fuel spraying. The substrate-coating systems were tested in long-term exposure tests to investigate their high-temperature oxidation behavior. Additionally, the ASRs were measured at 700 °C for 1000 h. Finally, a real coated interconnect was used in a SOFC single-cell stack for 6000 h. Post-mortem analysis was carried out with scanning electron microscopy. The deposited coatings reduced significantly the oxidation of the metal, exhibited low and stable ASR and reduced effectively the migration of chromium.

  14. Evaluation of Ni-Cr-base alloys for SOFC interconnect applications

    NASA Astrophysics Data System (ADS)

    Yang, Zhenguo; Xia, Guan-Guang; Stevenson, Jeffry W.

    To further understand the suitability of Ni-Cr-base alloys for solid oxide fuel cell (SOFC) interconnect applications, three commercial Ni-Cr-base alloys, Haynes 230, Hastelloy S and Haynes 242 were selected and evaluated for oxidation behavior under different exposure conditions, scale conductivity and thermal expansion. Haynes 230 and Hastelloy S, which have a relatively high Cr content, formed a thin scale mainly comprised of Cr 2O 3 and (Mn,Cr,Ni) 3O 4 spinels under SOFC operating conditions, demonstrating excellent oxidation resistance and a high scale electrical conductivity. In contrast, a thick double-layer scale with a NiO outer layer above a chromia-rich substrate was grown on Haynes 242 in moist air or at the air side of dual exposure samples, indicating limited oxidation resistance for the interconnect application. With a face-centered-cubic (FCC) substrate, all three alloys possess a coefficient of thermal expansion (CTE) that is higher than that of candidate ferritic stainless steels, e.g. Crofer22 APU. Among the three alloys, Haynes 242, which is heavily alloyed with W and Mo and contains a low Cr content, demonstrated the lowest average CTE at 13.1 × 10 -6 K -1 from room temperature to 800 °C, but it was also observed that the CTE behavior of Haynes 242 was very non-linear.

  15. Behaviour of various glass-ceramic sealants with ferritic steels under simulated SOFC stack conditions

    NASA Astrophysics Data System (ADS)

    Haanappel, V. A. C.; Shemet, V.; Gross, S. M.; Koppitz, Th.; Menzler, N. H.; Zahid, M.; Quadakkers, W. J.

    The suitability of various combinations of glass-ceramic sealants with high-chromium ferritic steels under conditions simulating SOFC stacks has been evaluated, i.e. three glass-ceramic sealants and seven types of ferritic steels. The test method used is based on test samples consisting of two metallic sheets, joined together with a glass-ceramic sealant. The outer side of the specimens was exposed to air for 400 h at 800 °C, whereas the inner side was exposed to hydrogen saturated with 3 vol.% water vapour. In particular, attention is paid to the influence of small amounts of additives to both the glass-ceramic sealant and the steel on the electrical and chemical behaviour of the specimens. Under experimental conditions simulating SOFC stacks, it appeared that excessive internal Cr oxidation of the ferritic steels, sometimes accompanied by external Fe-oxide formation, only occurred in the case of glass-ceramics containing minor amounts of PbO. This internal oxidation finally resulted in a volume change of the ferritic steel, which was manifested in bulging of the steel. As a consequence, the glass-ceramic was pushed away from the steel surface and crack formation at the glass-ceramic-steel interface occurred. The rate of corrosion attack strongly depended on the detailed steel composition. Increasing Si content apparently increased the rate of the corrosion attack, and thus possibly decreasing the time for the occurrence of short-circuiting.

  16. Evaluation of Ni-Cr-Base Alloys for SOFC Interconnect Applications

    SciTech Connect

    Yang, Z Gary; Xia, Gordon; Stevenson, Jeffry W.

    2006-10-06

    To further understand the suitability of Ni-Cr-base alloys for solid oxide fuel cell (SOFC) interconnect applications, three commercial Ni-Cr-base alloys, Haynes 230, Hastelloy S and Haynes 242 were selected and evaluated for oxidation behavior under different exposure conditions, scale conductivity and thermal expansion. Haynes 230 and Hastelloy S, which have a relatively high Cr content, formed a thin scale mainly comprised of Cr2O3 and (Mn,Cr,Ni)3O4 spinels under SOFC operating conditions, demonstrating excellent oxidation resistance and a high scale electrical conductivity. In contrast, a thick double-layer scale with a NiO outer layer above a chromia-rich substrate was grown on Haynes 242 in moist air or at the air side of dual exposure samples, indicating limited oxidation resistance for the interconnect application. With a face-centered-cubic (FCC) substrate, all three alloys possess a coefficient of thermal expansion (CTE) that is higher than that of candidate ferritic stainless steels, e.g. Crofer22 APU. Among the three alloys, Haynes 242, which is heavily alloyed with W and Mo and contains a low Cr content, demonstrated the lowest average CTE at 13.1x10-6 K-1 from room temperature to 800oC, but it was also observed that the CTE behavior of Haynes 242 was very nonlinear.

  17. Investigation of Performance of SCN-1 Pure Glass as Sealant Used in SOFC

    SciTech Connect

    Liu, Wenning N.; Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2010-03-01

    As its name implies, self-healing glass seal has the potential of restoring its mechanical properties upon being reheated to stack operating temperature, even when it has experienced some cooling induced damage/crack at room temperature. Such a self-healing feature is desirable for achieving high seal reliability during thermal cycling. On the other hand, self-healing glass is also characterized by its low mechanical stiffness and high creep rate at the typical operating temperature of SOFCs. Therefore, from a design’s perspective, it is important to know the long term geometric stability and thermal mechanical behaviors of the self-healing glass under the stack operating conditions. These predictive capabilities will guide the design and optimization of a reliable sealing system that potentially utilizes self-healing glass as well as other ceramic seal components in achieving the ultimate goal of SOFC. In this report, we focused on predicting the effects of various generic seal design parameters on the stresses in the seal. For this purpose, we take the test cell used in the leakage test for compliant glass seals conducted in PNNL as our initial modeling geometry. The effect of the ceramic stopper on the geometry stability of the self-healing glass sealants is studied first. Then we explored the effect of various interfaces such as stopper and glass, stopper and PEN, as well stopper and IC plate, on the geometry stability and reliability of glass during the operating and cooling processes.

  18. A Symmetrical, Planar SOFC Design for NASA's High Specific Power Density Requirements

    NASA Technical Reports Server (NTRS)

    Cable, Thomas L.; Sofie, Stephen W.

    2007-01-01

    Solid oxide fuel cell (SOFC) systems for aircraft applications require an order of magnitude increase in specific power density (1.0 kW/kg) and long life. While significant research is underway to develop anode supported cells which operate at temperatures in the range of 650-800 C, concerns about Cr-contamination from the metal interconnect may drive the operating temperature down further, to 750 C and lower. Higher temperatures, 900-1000 C, are more favorable for SOFC stacks to achieve specific power densities of 1.0 kW/kg. Since metal interconnects are not practical at these high temperatures and can account for up to 75% of the weight of the stack, NASA is pursuing a design that uses a thin, LaCrO3-based ceramic interconnect that incorporates gas channels into the electrodes. The bi-electrode supported cell (BSC) uses porous YSZ scaffolds, on either side of a 10-20 microns electrolyte. The porous support regions are fabricated with graded porosity using the freeze-tape casting process which can be tailored for fuel and air flow. Removing gas channels from the interconnect simplifies the stack design and allows the ceramic interconnect to be kept thin, on the order of 50 -100 microns. The YSZ electrode scaffolds are infiltrated with active electrode materials following the high temperature sintering step. The NASA-BSC is symmetrical and CTE matched, providing balanced stresses and favorable mechanical properties for vibration and thermal cycling.

  19. 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.

  20. 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.

  1. Molecular interactions between albumin and proximal tubular cells.

    PubMed

    Brunskill, N J

    1998-01-01

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

  2. Tubular precipitation and redox gradients on a bubbling template

    PubMed Central

    Stone, David A.; Goldstein, Raymond E.

    2004-01-01

    Tubular structures created by precipitation abound in nature, from chimneys at hydrothermal vents to soda straws in caves. Their formation is controlled by chemical gradients within which precipitation occurs, defining a surface that templates the growing structure. We report a self-organized periodic templating mechanism producing tubular structures electrochemically in iron-ammonium-sulfate solutions; iron oxides precipitate on the surface of bubbles that linger at the tube rim and then detach, leaving behind a ring of material. The acid–base and redox gradients spontaneously generated by diffusion of ammonia from the bubble into solution organize radial compositional layering within the tube wall, a mechanism studied on a larger scale by complex Liesegang patterns of iron oxides formed as ammonia diffuses through a gel containing FeSO4. When magnetite forms within the wall, a tube may grow curved in an external magnetic field. Connections with free-boundary problems in speleothem formation are emphasized. PMID:15284444

  3. 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

  4. 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.

  5. 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.

  6. Testing composite-to-metal tubular lap joints

    NASA Astrophysics Data System (ADS)

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

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

  7. An early Cambrian agglutinated tubular lophophorate with brachiopod characters

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  8. Functionalized organic nanotubes as tubular nonviral gene transfer vector.

    PubMed

    Ding, Wuxiao; Wada, Momoyo; Kameta, Naohiro; Minamikawa, Hiroyuki; Shimizu, Toshimi; Masuda, Mitsutoshi

    2011-11-30

    Tubular nanomaterials are expected to represent a novel nonviral gene transfer vectors due to the unique morphology and potential biological functionalities. Here we rationally constructed functionalized organic nanotubes (ONTs) for gene delivery through the co-assembly of bipolar glycolipid, arginine-lipid and PEG-lipid. The arginine- and PEG-functionalized ONTs efficiently formed complexes with plasmid DNA without aggregation, and protect DNA from enzymatic degradation; while the arginine-functionalized ONTs aggregated with DNA as large bundles. Long ONTs exceeding 1μm in length was rarely taken up into the cells, while those with a length of 400-800nm could effectively deliver plasmid DNA into cells and induce high transgene expression of green fluorescense protein. This study demonstrated the usefulness of functionalized ONT in gene delivery, and the functionalized ONT represents a novel type of tubular nonviral gene transfer vector.

  9. Tubular space truss structure for SKITTER 2 robot

    NASA Astrophysics Data System (ADS)

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

    1988-05-01

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

  10. Lipasuria in acute pancreatitis: result of tubular dysfunction?

    PubMed

    Muench, R; Buehler, H; Kehl, O; Ammann, R

    1987-01-01

    Lipase, in contrast to amylase, is completely reabsorbed by the proximal tubules after glomerular filtration. Therefore, no lipase is detectable in the unconcentrated urine according to the current opinion. The handling of lipase (detected with an enzyme-immunoassay) by the kidney was investigated in comparison with creatinine, amylase, and beta-2-microglobulin by clearance studies in acute pancreatitis (n = 10), burn injury (n = 4), glomerular proteinuria (n = 8), and controls without evidence of pancreatic or renal diseases (n = 5). In initial stages of acute pancreatitis a measurable clearance of lipase (mean: 49.6 microliters/min, range: 0.5-234) was found in association with corresponding increased clearances of beta-2-microglobulin (mean: 10.5 ml/min, range: 0.02-58.9) and of amylase (mean: 8.9 ml/min, range: 2.4-22.6) in nine of ten patients. This finding is consistent with a defect of tubular function. However, regression analysis failed to show a significant correlation between lipase and beta-2-microglobulin clearance. Repeated measurements during the course of pancreatitis in seven patients showed reversibility of tubular dysfunction. In patients with burn injury a similar elevation of clearances of beta-2-microglobulin and of amylase was found, but tubular dysfunction in this condition was not associated with lipasuria. In glomerular proteinuria a lipase clearance was found in two of five cases with moderate, and in the other three cases with severe impairment of creatinine clearance. beta-2-microglobulin clearance was normal in the former and only slightly elevated in the latter group. In conclusion lipase is measurable in the urine of most patients with acute pancreatitis as a result of a reversible tubular dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)

  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. Tissue cell assisted fabrication of tubular catalytic platinum microengines

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  13. Predicting the ultimate potential of natural gas SOFC power cycles with CO2 capture - Part B: Applications

    NASA Astrophysics Data System (ADS)

    Campanari, Stefano; Mastropasqua, Luca; Gazzani, Matteo; Chiesa, Paolo; Romano, Matteo C.

    2016-09-01

    An important advantage of solid oxide fuel cells (SOFC) as future systems for large scale power generation is the possibility of being efficiently integrated with processes for CO2 capture. Focusing on natural gas power generation, Part A of this work assessed the performances of advanced pressurised and atmospheric plant configurations (SOFC + GT and SOFC + ST, with fuel cell integration within a gas turbine or a steam turbine cycle) without CO2 separation. This Part B paper investigates such kind of power cycles when applied to CO2 capture, proposing two ultra-high efficiency plant configurations based on advanced intermediate-temperature SOFCs with internal reforming and low temperature CO2 separation process. The power plants are simulated at the 100 MW scale with a set of realistic assumptions about FC performances, main components and auxiliaries, and show the capability of exceeding 70% LHV efficiency with high CO2 capture (above 80%) and a low specific primary energy consumption for the CO2 avoided (1.1-2.4 MJ kg-1). Detailed results are presented in terms of energy and material balances, and a sensitivity analysis of plant performance is developed vs. FC voltage and fuel utilisation to investigate possible long-term improvements. Options for further improvement of the CO2 capture efficiency are also addressed.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. Hierarchically designed electrospun tubular scaffolds for cardiovascular applications.

    PubMed

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

    2011-10-01

    Hierarchically designed tubular scaffolds with bi-layer and multi-layer structures are expected to mimic native vessels in its structural geometry. A new approach for the fabrication of hierarchically designed tubular scaffold with suitable morphology was introduced through electrospinning technique. Among these scaffolds, bi-layer scaffold had a single inner and outer layer whereas multilayer scaffold had more number of inner layers. The inner layer/layers of the scaffolds were made up of aligned poly (lactic acid) (PLA) fibers for EC adhesion where as outer layers were composed of random fibers of poly (caprolactone) (PCL) and PLA providing larger pores for SMC penetration. The fabricated scaffolds were characterized by FTIR spectroscopy and Differential Thermal Analysis (DTA) and examined by evaluating cellular interactions. Human Umbilical Vein Endothelial Cells (HUVECs) seeded on aligned PLA fibers showed enhanced cellular orientation and cytoskeletal organization. In addition, the PCL-PLA composite random fibers supported SMC adhesion and proliferation sufficiently. The functionality of the endothelial cells grown on the PLA-aligned scaffold was also found to be satisfactory. Lining the constructs with a luminal monolayer of well-organized ECs along with homogenously distributed SMCs surrounding them might result in vascular conduits suitable for in vivo applications. Since this hierarchically designed tubular scaffold closely mimics the morphology of native vessel, this could be a better candidate for vascular tissue engineering. PMID:22195478

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

    PubMed

    Gattineni, Jyothsna; Baum, Michel

    2015-12-01

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

  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. Pediatric Tubular Pulmonary Heart Valve from Decellularized Engineered Tissue Tubes

    PubMed Central

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

    2015-01-01

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

  3. The rebirth of interest in renal tubular function.

    PubMed

    Lowenstein, Jerome; Grantham, Jared J

    2016-06-01

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

  4. The Development of Low-Cost Integrated Composite Seal for SOFC: Materials and Design Methodologies

    SciTech Connect

    Xinyu Huang; Kristoffer Ridgeway; Srivatsan Narasimhan; Serg Timin; Wei Huang; Didem Ozevin; Ken Reifsnider

    2006-07-31

    This report summarizes the work conducted by UConn SOFC seal development team during the Phase I program and no cost extension. The work included composite seal sample fabrication, materials characterizations, leak testing, mechanical strength testing, chemical stability study and acoustic-based diagnostic methods. Materials characterization work revealed a set of attractive material properties including low bulk permeability, high electrical resistivity, good mechanical robustness. Composite seal samples made of a number of glasses and metallic fillers were tested for sealing performance under steady state and thermal cycling conditions. Mechanical testing included static strength (pull out) and interfacial fracture toughness measurements. Chemically stability study evaluated composite seal material stability after aging at 800 C for 168 hrs. Acoustic based diagnostic test was conducted to help detect and understand the micro-cracking processes during thermal cycling test. The composite seal concept was successfully demonstrated and a set of material (coating composition & fillers) were identified to have excellent thermal cycling performance.

  5. High-temperature solid oxide fuel cell (SOFC) generator development project: Environmental Assessment

    SciTech Connect

    Not Available

    1991-08-01

    The proposed project involves research, development, fabrication, and testing of solid oxide fuel cells/generators. All of the work, with the exception of various SOFC generator tests, would be conducted at two existing permitted Westinghouse facilities in the greater metropolitan Pittsburgh, Pennsylvania area. The DOE has prepared this Environmental Assessment (EA). This site-specific analysis addresses the two existing permitted Westinghouse facilities. The sources of information for this EA include the following: the technical proposal submitted as part of the assistance application by the Westinghouse Electric Corporation; discussions with the Westinghouse staff and information provided on the sites to be utilized; and site visits during work conducted under the prior Westinghouse effort with DOE.

  6. Model-based prediction of suitable operating range of a SOFC for an Auxiliary Power Unit

    NASA Astrophysics Data System (ADS)

    Pfafferodt, Matthias; Heidebrecht, Peter; Stelter, Michael; Sundmacher, Kai

    This paper presents a one-dimensional steady state model of a solid oxide fuel cell (SOFC) to be used in an Auxiliary Power Unit (APU). The fuel cell is fed a prereformed gas from an external autothermic reformer. In addition to the three electrochemical reactions (reduction of oxygen at the cathode, oxidation of hydrogen and carbon monoxide at the anode) the water-gas shift reaction and the methane steam reforming reaction are taken into account in the anode channel. The model predicts concentrations and temperatures and uses an equivalent circuit approach to describe the current-voltage characteristics of the cell. The model equations are presented and their implementation into the commercial mathematical software FEMLAB is discussed. An application of this model is used to determine suitable operating parameters with respect to optimum performance and allowable temperature.

  7. SOFC-based micro-CHP system as an example of efficient power generation unit

    NASA Astrophysics Data System (ADS)

    Kupecki, Jakub; Badyda, Krzysztof

    2011-12-01

    Microscale combined heat and power (CHP) unit based on solid oxide fuel cells (SOFC) for distributed generation was analyzed. Operation principle is provided, and the technology development in recent years is briefly discussed. System baseline for numerical analysis under steady-state operation is given. Grid-connected unit, fuelled by biogas corresponds to potential market demand in Europe, therefore has been selected for analysis. Fuel processing method for particular application is described. Results of modeling performed in ASPEN Plus engineering software with certain assumptions are presented and discussed. Due to high system electrical efficiency exceeding 40%, and overall efficiency over 80%, technology is an example of highly competitive and sustainable energy generation unit.

  8. Preparation and characterisation of SOFC anodic materials based on Ce-Cu

    NASA Astrophysics Data System (ADS)

    Fuerte, A.; Valenzuela, R. X.; Daza, L.

    Ce-Cu mixed oxide precursors with varing Ce:Cu atomic ratio have been prepared by freeze-drying and microemulsion coprecipitation methods. Nanostructured particles having different properties have been obtained. Physicochemical properties have been studied with X-ray diffraction, UV-vis spectroscopy, nitrogen adsorption-desorption, mercury intrusion porosimetry, ICP-AES, conductivity measurement and thermal expansion coefficient. All samples show fluorite structure with slight copper surface enrichment for samples having high copper content. Microemulsion method allows the introduction of a large quantity of copper into the cerium oxide structure, obtaining a nanostructured mixed oxide of high surface area. On the other hand, freeze-drying samples does not show evidence of copper incorporation to the lattice of cerium oxide. All materials have a thermal expansion coefficient similar to other components of SOFC.

  9. Development of Parametric Mass and Volume Models for an Aerospace SOFC/Gas Turbine Hybrid System

    NASA Technical Reports Server (NTRS)

    Tornabene, Robert; Wang, Xiao-yen; Steffen, Christopher J., Jr.; Freeh, Joshua E.

    2005-01-01

    In aerospace power systems, mass and volume are key considerations to produce a viable design. The utilization of fuel cells is being studied for a commercial aircraft electrical power unit. Based on preliminary analyses, a SOFC/gas turbine system may be a potential solution. This paper describes the parametric mass and volume models that are used to assess an aerospace hybrid system design. The design tool utilizes input from the thermodynamic system model and produces component sizing, performance, and mass estimates. The software is designed such that the thermodynamic model is linked to the mass and volume model to provide immediate feedback during the design process. It allows for automating an optimization process that accounts for mass and volume in its figure of merit. Each component in the system is modeled with a combination of theoretical and empirical approaches. A description of the assumptions and design analyses is presented.

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

    PubMed

    Baines, Richard J; Brunskill, Nigel J

    2008-01-01

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

  11. High-Temperature Desulfurization of Heavy Fuel-Derived Reformate Gas Streams for SOFC Applications

    NASA Technical Reports Server (NTRS)

    Flytzani-Stephanopoulos, Maria; Surgenor, Angela D.

    2007-01-01

    Desulfurization of the hot reformate gas produced by catalytic partial oxidation or autothermal reforming of heavy fuels, such as JP-8 and jet fuels, is required prior to using the gas in a solid oxide fuel cell (SOFC). Development of suitable sorbent materials involves the identification of sorbents with favorable sulfidation equilibria, good kinetics, and high structural stability and regenerability at the SOFC operating temperatures (650 to 800 C). Over the last two decades, a major barrier to the development of regenerable desulfurization sorbents has been the gradual loss of sorbent performance in cyclic sulfidation and regeneration at such high temperatures. Mixed oxide compositions based on ceria were examined in this work as regenerable sorbents in simulated reformate gas mixtures and temperatures greater than 650 C. Regeneration was carried out with dilute oxygen streams. We have shown that under oxidative regeneration conditions, high regeneration space velocities (greater than 80,000 h(sup -1)) can be used to suppress sulfate formation and shorten the total time required for sorbent regeneration. A major finding of this work is that the surface of ceria and lanthanan sorbents can be sulfided and regenerated completely, independent of the underlying bulk sorbent. This is due to reversible adsorption of H2S on the surface of these sorbents even at temperatures as high as 800 C. La-rich cerium oxide formulations are excellent for application to regenerative H2S removal from reformate gas streams at 650 to 800 C. These results create new opportunities for compact sorber/regenerator reactor designs to meet the requirements of solid oxide fuel cell systems at any scale.

  12. Activation of H(2) oxidation at sulphur-exposed Ni surfaces under low temperature SOFC conditions.

    PubMed

    Deleebeeck, Lisa; Shishkin, Maxim; Addo, Paul; Paulson, Scott; Molero, Hebert; Ziegler, Tom; Birss, Viola

    2014-05-28

    Ni-YSZ (yttria-stabilized zirconia) cermets are known to be very good anodes in solid oxide fuel cells (SOFCs), which are typically operated at 700-1000 °C. However, they are expected to be increasingly degraded as the operating temperature is lowered in the presence of H2S (5-10 ppm) in the H2 fuel stream. However, at 500 to 600 °C, a temperature range rarely examined for sulphur poisoning, but of great interest for next generation SOFCs, we report that H2S-exposed Ni-YSZ anodes are catalytic towards the H2 oxidation reaction, rather than poisoned. By analogy with bulk Ni3S2/YSZ anodes, shown previously to enhance H2 oxidation kinetics, it is proposed that a thin layer of Ni sulphide, akin to Ni3S2, is forming, at least at the triple point boundary (TPB) region under our conditions. To explain why Ni3S2/YSZ is so active, it is shown from density functional theory (DFT) calculations that the O(2-) anions at the Ni3S2/YSZ TPB are more reactive towards hydrogen oxidation than is O(2-) at the Ni/YSZ TPB. This is accounted for primarily by structural transformations of Ni3S2 during H2 oxidation, rather than by the electronic properties of this interface. To understand why a thin layer of Ni3S2 could form when a single monolayer of sulphur on the Ni surface is the predicted surface phase under our conditions, it is possible that the reaction of H2 with O(2-), forming water, prevents sulphur from re-equilibrating to H2S. This may then promote Ni sulphide formation, at least in the TPB region.

  13. 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.

  14. Reconstruction of Female Urethra with Tubularized Anterior Vaginal Flap

    PubMed Central

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

    2016-01-01

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

  15. Reconstruction of Female Urethra with Tubularized Anterior Vaginal Flap

    PubMed Central

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

    2016-01-01

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

  16. 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.

  17. Hepatocyte nuclear factor 1β controls nephron tubular development.

    PubMed

    Massa, Filippo; Garbay, Serge; Bouvier, Raymonde; Sugitani, Yoshinobu; Noda, Tetsuo; Gubler, Marie-Claire; Heidet, Laurence; Pontoglio, Marco; Fischer, Evelyne

    2013-02-01

    Nephron morphogenesis is a complex process that generates blood-filtration units (glomeruli) connected to extremely long and patterned tubular structures. Hepatocyte nuclear factor 1β (HNF1β) is a divergent homeobox transcription factor that is expressed in kidney from the first steps of nephrogenesis. Mutations in HNF1B (OMIM #137920) are frequently found in patients with developmental renal pathologies, the mechanisms of which have not been completely elucidated. Here we show that inactivation of Hnf1b in the murine metanephric mesenchyme leads to a drastic tubular defect characterized by the absence of proximal, distal and Henle's loop segments. Nephrons were eventually characterized by glomeruli, with a dilated urinary space, directly connected to collecting ducts via a primitive and short tubule. In the absence of HNF1β early nephron precursors gave rise to deformed S-shaped bodies characterized by the absence of the typical bulge of epithelial cells at the bend between the mid and lower segments. The lack of this bulge eventually led to the absence of proximal tubules and Henle's loops. The expression of several genes, including Irx1, Osr2 and Pou3f3, was downregulated in the S-shaped bodies. We also observed decreased expression of Dll1 and the consequent defective activation of Notch in the prospective tubular compartment of comma- and S-shaped bodies. Our results reveal a novel hierarchical relationship between HNF1β and key genes involved in renal development. In addition, these studies define a novel structural and functional component of S-shaped bodies at the origin of tubule formation.

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

    PubMed Central

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

    2013-01-01

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

  19. 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.

  20. Amylase/creatinine clearance ratio and tubular proteinuria in acute pancreatitis.

    PubMed

    Lankisch, P G; Wolfrum, D I; Koop, H; Winckler, K

    1979-01-01

    Amylase/creatinine clearance ratio (CAm/CCr), urinary protein concentration and urinary protein pattern were studied in 102 samples from 27 patients with acute pancreatitis and in 46 controls. Raised CAm/CCr, proteinuria and a tubular protein pattern were present in 74, 56 and 96% of the patients, respectively. However, CAm/CCr and proteinuria and CAm/CCr and tubular protein pattern were not correlated. These results do not support the suggestion that an elevated CAm/CCr in acute pancreatitis is due to generalized tubular protein reabsorption failure presenting with tubular proteinuria.

  1. Large-sized tubular graphite cones with nanotube tips

    SciTech Connect

    Shang, N.G.; Jiang, X.

    2005-10-17

    Tubular graphite cones (TGCs) have been grown on planar steel substrates by microwave plasma-assisted chemical vapor deposition with a high concentration of methane and at a high substrate temperature. The largest TGCs can reach 110 {mu}m in length and 10 {mu}m in diameter at the root. Unique TGCs terminated in long extruding carbon nanotube tips are realized. Scanning micro-Raman spectroscopy of individual TGCs shows a high crystallinity of the tips and more disordered structure of the roots. A possible growth mechanism of TGCs is presented.

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

    PubMed

    Kulkarni, Manjunath

    2016-02-01

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

  3. 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. PMID:16133056

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

    PubMed

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

    2016-10-20

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

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

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

    PubMed

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

    2016-08-01

    Surface and interfacial creases induced by biological growth are common types of instability in soft biological tissues. This study focuses on the criteria for the onset of surface and interfacial creases as well as their morphological evolution in a growing bilayer soft tube within a confined environment. Critical growth ratios for triggering surface and interfacial creases are investigated both analytically and numerically. Analytical interpretations provide preliminary insights into critical stretches and growth ratios for the onset of instability and formation of both surface and interfacial creases. However, the analytical approach cannot predict the evolution pattern of the model after instability; therefore nonlinear finite element simulations are carried out to replicate the poststability morphological patterns of the structure. Analytical and computational simulation results demonstrate that the initial geometry, growth ratio, and shear modulus ratio of the layers are the most influential factors to control surface and interfacial crease formation in this soft tubular bilayer. The competition between the stretch ratios in the free and interfacial surfaces is one of the key driving factors to determine the location of the first crease initiation. These findings may provide some fundamental understanding in the growth modeling of tubular biological tissues such as esophagi and airways as well as offering useful clues into normal and pathological functions of these tissues. PMID:27627333

  11. 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.

  12. Nano-Tubular Cellulose for Bioprocess Technology Development

    PubMed Central

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

    2012-01-01

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

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  15. 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.

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

    PubMed

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

    2016-08-01

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

  17. 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.

  18. 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.

  19. Materials Properties Database for Selection of High-Temperature Alloys and Concepts of Alloy Design for SOFC Applications

    SciTech Connect

    Yang, Z Gary; Paxton, Dean M.; Weil, K. Scott; Stevenson, Jeffry W.; Singh, Prabhakar

    2002-11-24

    To serve as an interconnect / gas separator in an SOFC stack, an alloy should demonstrate the ability to provide (i) bulk and surface stability against oxidation and corrosion during prolonged exposure to the fuel cell environment, (ii) thermal expansion compatibility with the other stack components, (iii) chemical compatibility with adjacent stack components, (iv) high electrical conductivity of the surface reaction products, (v) mechanical reliability and durability at cell exposure conditions, (vii) good manufacturability, processability and fabricability, and (viii) cost effectiveness. As the first step of this approach, a composition and property database was compiled for high temperature alloys in order to assist in determining which alloys offer the most promise for SOFC interconnect applications in terms of oxidation and corrosion resistance. The high temperature alloys of interest included Ni-, Fe-, Co-base superal

  20. Evaluation of methods for thermal management in a coal-based SOFC turbine hybrid through numerical simulation

    SciTech Connect

    Tucker, D.A.; VanOsdol, J.G.; Liese, E.A.; Lawson, L.; Zitney, S.E.; Gemmen, R.S.; Ford, J.C.; Haynes, C.

    2001-01-01

    Managing the temperatures and heat transfer in the fuel cell of a solid oxide fuel cell (SOFC) gas turbine (GT) hybrid fired on coal syngas presents certain challenges over a natural gas based system, in that the latter can take advantage of internal reforming to offset heat generated in the fuel cell. Three coal based SOFC/GT configuration designs for thermal management in the main power block are evaluated using steady state numerical simulations developed in ASPEN Plus. A comparison is made on the basis of efficiency, operability issues and component integration. To focus on the effects of different power block configurations, the analysis assumes a consistent syngas composition in each case, and does not explicitly include gasification or syngas cleanup. A fuel cell module rated at 240MW was used as a common basis for three different methods. Advantages and difficulties for each configuration are identified in the simulations.

  1. Development of low coefficient of thermal expansion (CTE) nickel alloys for potential use as interconnects in SOFC

    SciTech Connect

    Alman, David E.; Jablonski, Paul D.

    2004-11-01

    This paper deals with the development of low coefficient of thermal expansion (CTE) nickel-base superalloys for potential use as interconnects for SOFC. Ni-Mo-Cr alloys were formulated with CTE on the order of 12.5 to 13.5 x10-6/°C. The alloys were vacuum induction melted and reduced to sheet via a combination of hot and cold working. Dilatometry was used to measure CTE of the alloys. Oxidation behavior of the alloys at 800°C in dry and moist air is reported. The results are compared to results for Haynes 230 (a commercial Ni-base superalloy) and for Crofer 22APU (a commercial ferritic stainless steel designed specifically for use as an SOFC interconnect).

  2. Design and application of PV power system for 100w to 10kw

    SciTech Connect

    Matlin, R.W.

    1982-06-01

    Photovoltaic systems are economically viable in remote areas where grid power is not available and where power requirements are modest. PV systems provide power for water pumping, navigation aids, and residential electrification. Water pumping applications are projected to provide the largest market. The world's largest PV pumping unit, a 25Kw centrifugal pump system used to irrigate 80 acres of corn in Nebraska, is shown. Volumetric style ''jack pumps'' have been installed in the Upper Volta, and in Arizona. Remote residential AC power systems at the Hopi reservation, and a navigational aid system in the St. Lawrence Seaway are also demonstrated. Life cycle costing has shown that it is preferable to use deep cycle batteries.

  3. The 28 GHZ, 10 KW, CW Gyrotron Generator for the VENUS ECR Ion Source at LBNL

    NASA Astrophysics Data System (ADS)

    Marks, M.; Evans, S.; Jory, H.; Holstein, D.; Rizzo, R.; Beck, P.; Cisto, B.; Leitner, D.; Lyneis, C. M.; Collins, D.; Dwinell, R. D.

    2005-03-01

    The VIA-301 Heatwave™ gyrotron generator was specifically designed to meet the requirements of the Venus ECR Ion Source at the Lawrence Berkeley National Laboratory (LBNL). VENUS (Versatile ECR ion source for NUclear Science) is a next generation superconducting ECR ion source, designed to produce high current, high charge state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the RIA (Rare Isotope Accelerator) front end [1]. This VIA-301 Heatwave™ gyrotron system provides 100 watts to 10 kW continuous wave (CW) RF output at 28 GHz. The RF output level is smoothly controllable throughout this entire range. The power can be set and maintained to within 10 watts at the higher power end of the power range and to within 30 watts at the lower power end of the power range. A dual directional coupler, analog conditioning circuitry, and a 12-bit analog input to the embedded controller are used to provide a power measurement accurate to within 2%. The embedded controller completes a feedback loop using an external command set point for desired power output. Typical control-loop-time is on the order of 500 mS. Hard-wired interlocks are provided for personnel safety and for protection of the generator system. In addition, there are software controlled interlocks for protection of the generator from high ambient temperature, high water temperature, and other conditions that would affect the performance of the generator or reduce the lifetime of the gyrotron. Cooling of the gyrotron and power supply is achieved using both water and forced circulation of ambient air. Water-cooling provides about 80% of the cooling requirement. Input power to the generator from the prime power line is less than 60 kW at full power. The Heatwave™ may be operated locally via its front panel or remotely via either RS-232 and/or Ethernet connections. Through the RS-232 the forward power, the reflected power, the

  4. The “SF” System of Sextupoles for the JLAB 10 KW Free Electron Laser Upgrade

    SciTech Connect

    George Biallas, Mark Augustine, Kenneth Baggett, David Douglas, Robin Wines

    2009-05-01

    The characteristics of the system of “SF” Sextupoles for the infrared Free Electron Laser Upgrade1 at the Thomas Jefferson National Accelerator Facility (JLab) are described. These eleven sextupoles possess a large field integral (2.15 T/m) with +/- 0.2%

  5. MAGNETIC MEASUREMENT OF THE 10 KW, IR FEL 180 DEGREE DIPOLE

    SciTech Connect

    Kenneth Baggett; George Biallas; Donald Bullard; Jeffery Dail; David Douglas; Tommy Hiatt; Michael Mccrea

    2003-05-01

    A family of large bending dipoles has been magnetically measured to support the 10 kW IR-FEL upgrade. This upgrade will allow for a wider wavelength range and an increase in the machine energy to operate between 80 MeV/c and 210 MeV/c. The dipole magnets allow the beam to bend 180 degrees over a 1 meter radius. The requirements for these magnets include varying field strengths, large horizontal apertures and parts in 10,000 field homogeneity as well as setability of core and integrated field. This paper will describe the process involved in measuring and achieving these requirements.

  6. The 28 GHZ, 10 KW, CW Gyrotron Generator for the VENUS ECR Ion Source at LBNL

    SciTech Connect

    Marks, M.; Evans, S.; Jory, H.; Holstein, D.; Rizzo, R.; Beck, P.; Cisto, B.; Leitner, D.; Lyneis, C.M.; Collins, D.; Dwinell, R.D.

    2005-03-15

    The VIA-301 Heatwave{sup TM} gyrotron generator was specifically designed to meet the requirements of the Venus ECR Ion Source at the Lawrence Berkeley National Laboratory (LBNL). VENUS (Versatile ECR ion source for NUclear Science) is a next generation superconducting ECR ion source, designed to produce high current, high charge state ions for the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. VENUS also serves as the prototype ion source for the RIA (Rare Isotope Accelerator) front end].This VIA-301 Heatwave{sup TM} gyrotron system provides 100 watts to 10 kW continuous wave (CW) RF output at 28 GHz. The RF output level is smoothly controllable throughout this entire range. The power can be set and maintained to within 10 watts at the higher power end of the power range and to within 30 watts at the lower power end of the power range. A dual directional coupler, analog conditioning circuitry, and a 12-bit analog input to the embedded controller are used to provide a power measurement accurate to within 2%. The embedded controller completes a feedback loop using an external command set point for desired power output. Typical control-loop-time is on the order of 500 mS. Hard-wired interlocks are provided for personnel safety and for protection of the generator system. In addition, there are software controlled interlocks for protection of the generator from high ambient temperature, high water temperature, and other conditions that would affect the performance of the generator or reduce the lifetime of the gyrotron. Cooling of the gyrotron and power supply is achieved using both water and forced circulation of ambient air. Water-cooling provides about 80% of the cooling requirement. Input power to the generator from the prime power line is less than 60 kW at full power. The Heatwave{sup TM} may be operated locally via its front panel or remotely via either RS-232 and/or Ethernet connections. Through the RS-232 the forward power, the reflected power

  7. MAGNETIC MODELING VS MEASUREMENTS OF THE DIPOLES FOR THE JLAB 10 KW FREE ELECTRON LASER UPGRADE

    SciTech Connect

    David Douglas; Robin Wines; Tom Hiatt; George Biallas; Kenneth Baggett; T.J. Schultheiss; V.A. Christina; J.W. Rathke; A. Smirnov; D. Newsham; Y. Luo; D. Yu

    2003-05-01

    Magnetic measurements of the six families of dipoles for the infrared Free Electron Laser Upgrade at the Thomas Jefferson National Accelerator Facility (Jlab) are compared to the magnetic models on which their design is based. The magnets were designed in parallel by three organizations. They used ANSYS, Radia or Opera 3D as a 3D magnetic modeling program. Comparison of the discrepancies between model and magnet measurement is presented along with analysis of their potential causes. These dipoles operate in two field ranges. The Injector/ Extractor Dipoles operate around 0.05 T and the Arc Dipoles and Optical Chicane Dipoles operate between 0.22 to 0.71 T. All magnets are required to meet core field and field integral flatness to parts in 104 over their good field region.

  8. Predicting the ultimate potential of natural gas SOFC power cycles with CO2 capture - Part A: Methodology and reference cases

    NASA Astrophysics Data System (ADS)

    Campanari, Stefano; Mastropasqua, Luca; Gazzani, Matteo; Chiesa, Paolo; Romano, Matteo C.

    2016-08-01

    Driven by the search for the highest theoretical efficiency, in the latest years several studies investigated the integration of high temperature fuel cells in natural gas fired power plants, where fuel cells are integrated with simple or modified Brayton cycles and/or with additional bottoming cycles, and CO2 can be separated via chemical or physical separation, oxy-combustion and cryogenic methods. Focusing on Solid Oxide Fuel Cells (SOFC) and following a comprehensive review and analysis of possible plant configurations, this work investigates their theoretical potential efficiency and proposes two ultra-high efficiency plant configurations based on advanced intermediate-temperature SOFCs integrated with a steam turbine or gas turbine cycle. The SOFC works at atmospheric or pressurized conditions and the resulting power plant exceeds 78% LHV efficiency without CO2 capture (as discussed in part A of the work) and 70% LHV efficiency with substantial CO2 capture (part B). The power plants are simulated at the 100 MW scale with a complete set of realistic assumptions about fuel cell (FC) performance, plant components and auxiliaries, presenting detailed energy and material balances together with a second law analysis.

  9. Chemical Compatibility of Barium-Calcium-Aluminosilicate Based Sealing Glasses with Ferritic Stainless Steel Interconnect in SOFCs

    SciTech Connect

    Yang, Z Gary; Meinhardt, Kerry D.; Stevenson, Jeffry W.

    2003-08-01

    In most planar SOFC stack designs, the interconnect, which is typically made from a ferritic stainless steel, is hermitically sealed to the ceramic PEN (Positive electrode-Electrolyte-Negative electrode) by a sealing glass. To maintain the structural stability and minimize degradation of the stack performance, the sealing glass must be chemically compatible with the stainless steel interconnect. In this study, a barium-calcium-aluminosilicate (BCAS) based glass-ceramic, specifically developed as a sealant in SOFC stacks, and a ferritic stainless steel (446) were selected as examples to increase the understanding the chemical compatibility issues in SOFC. Evaluation of the interfaces of coupon joints indicated that interactions between the BCAS glass-ceramic and the ferritic stainless steel was dependent on the exposure conditions. At the edges of joints, where oxygen or air was accessible, the interaction often led to the formation of BaCrO4, while in the interior of the joints, chromium or chromia dissolved into the glass to form a thin layer of chromium rich solid solution. It was also found that, in the interior of the joints, the interaction often resulted in the formation of pores aligned along the interface. It appears the pore formation along the interface can be avoided through a pre-heat treatment.

  10. Experimental Study of the Aging and Self-Healing of Glass/Ceramic Sealant Used in SOFCs

    SciTech Connect

    Liu, Wenning N.; Sun, Xin; Koeppel, Brian J.; Khaleel, Mohammad A.

    2010-01-01

    High operating temperatures of solid oxide fuel cells (SOFCs) require that sealant must function at a high temperature between 600oC and 900oC and in the oxidizing and reducing environments of fuel and air. This paper describes tests to investigate the temporal evolution of the volume fraction of ceramic phases, the evolution of micro-damage, and the self-healing behavior of the glass ceramic sealant used in SOFCs. It was found that after the initial sintering process, further crystallization of the glass ceramic sealant does not stop, but slows down and reduces the residual glass content while boosting the ceramic crystalline content. Under the long-term operating environment, distinct fibrous and needle-like crystals in the amorphous phase disappeared, and smeared/diffused phase boundaries between the glass phase and ceramic phase were observed. Meanwhile, the micro-damage was induced by the cooling-down process from the operating temperature to the room temperature, which can potentially degrade the mechanical properties of the glass/ceramic sealant. The glass/ceramic sealant self-healed upon reheating to the SOFC operating temperature, which can restore the mechanical performance of the glass/ceramic sealant.

  11. Predicting the ultimate potential of natural gas SOFC power cycles with CO2 capture - Part A: Methodology and reference cases

    NASA Astrophysics Data System (ADS)

    Campanari, Stefano; Mastropasqua, Luca; Gazzani, Matteo; Chiesa, Paolo; Romano, Matteo C.

    2016-08-01

    Driven by the search for the highest theoretical efficiency, in the latest years several studies investigated the integration of high temperature fuel cells in natural gas fired power plants, where fuel cells are integrated with simple or modified Brayton cycles and/or with additional bottoming cycles, and CO2 can be separated via chemical or physical separation, oxy-combustion and cryogenic methods. Focusing on Solid Oxide Fuel Cells (SOFC) and following a comprehensive review and analysis of possible plant configurations, this work investigates their theoretical potential efficiency and proposes two ultra-high efficiency plant configurations based on advanced intermediate-temperature SOFCs integrated with a steam turbine or gas turbine cycle. The SOFC works at atmospheric or pressurized conditions and the resulting power plant exceeds 78% LHV efficiency without CO2 capture (as discussed in part A of the work) and 70% LHV efficiency with substantial CO2 capture (part B). The power plants are simulated at the 100 MW scale with a complete set of realistic assumptions about fuel cell (FC) performance, plant components and auxiliaries, presenting detailed energy and material balances together with a second law analysis.

  12. High temperature phase transition in SOFC anodes based on Sr{sub 2}MgMoO{sub 6-{delta}}

    SciTech Connect

    Marrero-Lopez, D.; Pena-Martinez, J.; Ruiz-Morales, J.C.; Martin-Sedeno, M.C.; Nunez, P.

    2009-05-15

    The double perovskite Sr{sub 2}MgMoO{sub 6-{delta}} has been recently reported as an efficient anode material for solid oxide fuel cells (SOFCs). In the present work, this material have been investigated by high temperature X-ray diffraction (XRD), differential scanning calorimetry (DSC) and impedance spectroscopy to further characterise its properties as SOFC anode. DSC and XRD measurements indicate that Sr{sub 2}MgMoO{sub 6-{delta}} exhibits a reversible phase transition around 275 deg. C from triclinic (I1-bar) with an octahedral tilting distortion to cubic (Fm3-barm) without octahedral distortion. This phase transition is continuous with increasing temperature without any sudden cell volume change during the phase transformation. The main effect of the phase transformation is observed in the electrical conductivity with a change in the activation energy at low temperature. La{sup 3+} and Fe-substituted Sr{sub 2}MgMoO{sub 6-{delta}} phases were also investigated, however these materials are unstable under oxidising conditions due to phase segregations above 600 deg. C. - Graphical abstract: The double perovskite Sr{sub 2}MgMoO{sub 6}, recently proposed as an efficient SOFC anode for direct hydrocarbon oxidation, exhibits a reversible structural phase transition from triclinic to cubic at 275 deg. C.

  13. Effect of SOFC Interconnect-Coating Interactions on Coating Properties and Performance

    SciTech Connect

    Jeffrey W. Fergus

    2012-09-05

    The high operating temperature of solid oxide fuel cells (SOFCs) provides good fuel flexibility which expands potential applications, but also creates materials challenges. One such challenge is the interconnect material, which was the focus of this project. In particular, the objective of the project was to understand the interaction between the interconnect alloy and ceramic coatings which are needed to minimize chromium volatilization and the associated chromium poisoning of the SOFC cathode. This project focused on coatings based on manganese cobalt oxide spinel phases (Mn,Co)3O4, which have been shown to be effective as coatings for ferritic stainless steel alloys. Analysis of diffusion couples was used to develop a model to describe the interaction between (Mn,Co)3O4 and Cr2O3 in which a two-layer reaction zone is formed. Both layers form the spinel structure, but the concentration gradients at the interface appear like a two-phase boundary suggesting that a miscibility gap is present in the spinel solid solution. A high-chromium spinel layer forms in contact with Cr2O3 and grows by diffusion of manganese and cobalt from the coating material to the Cr2O3. The effect of coating composition, including the addition of dopants, was evaluated and indicated that the reaction rate could be decreased with additions of iron, titanium, nickel and copper. Diffusion couples using stainless steel alloys (which form a chromia scale) had some similarities and some differences as compared to those with Cr2O3. The most notable difference was that the high-chromium spinel layer did not form in the diffusion couples with stainless steel alloys. This difference can be explained using the reaction model developed in this project. In particular, the chromia scale grows at the expense of the alloy, the high-chromia layer grows at the expense of chromia scale and the high-chromia layer is consumed by diffusion of chromium into the coating material. If the last process (dissolution

  14. Electrospinning of small diameter 3-D nanofibrous tubular scaffolds with controllable nanofiber orientations for vascular grafts.

    PubMed

    Wu, Huijun; Fan, Jintu; Chu, Chih-Chang; Wu, Jun

    2010-12-01

    The control of nanofiber orientation in nanofibrous tubular scaffolds can benefit the cell responses along specific directions. For small diameter tubular scaffolds, however, it becomes difficult to engineer nanofiber orientation. This paper reports a novel electrospinning technique for the fabrication of 3-D nanofibrous tubular scaffolds with controllable nanofiber orientations. Synthetic absorbable poly-ε-caprolactone (PCL) was used as the model biomaterial to demonstrate this new electrospinning technique. Electrospun 3-D PCL nanofibrous tubular scaffolds of 4.5 mm in diameter with different nanofiber orientations (viz. circumferential, axial, and combinations of circumferential and axial directions) were successfully fabricated. The degree of nanofiber alignment in the electrospun 3-D tubular scaffolds was quantified by using the fast Fourier transform (FFT) analysis. The results indicated that excellent circumferential nanofiber alignment could be achieved in the 3-D nanofibrous PCL tubular scaffolds. The nanofibrous tubular scaffolds with oriented nanofibers had not only directional mechanical property but also could facilitate the orientation of the endothelial cell attachment on the fibers. Multiple layers of aligned nanofibers in different orientations can produce 3-D nanofibrous tubular scaffolds of different macroscopic properties. PMID:20890639

  15. 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.

  16. 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.

  17. Low gas prices and rig count cut business for makers of oil country tubular goods

    SciTech Connect

    1995-09-01

    After years of scavenging used drill pipe and trying everything they could think of to make existing pipe last, contractors in the petroleum industry are buying more new pipe. Although supplies of tubular goods are growing tighter, the supply and demand curves haven`t met. However, while the market for drill pipe may be increasing, the market for other tubular goods is decreasing.

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

    SciTech Connect

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

    1987-04-01

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

  19. 78 FR 77420 - Certain Oil Country Tubular Goods From the Republic of Turkey: Preliminary Negative...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-23

    ... Duty Investigations, 78 FR 45505 (July 29, 2013). \\2\\ Maverick Tube Corporation, United States Steel... International Trade Administration Certain Oil Country Tubular Goods From the Republic of Turkey: Preliminary... tubular goods (OCTG) from the Republic of Turkey (Turkey). The period of investigation is January 1,...

  20. Development of a high-performance composite cathode for LT-SOFC

    NASA Astrophysics Data System (ADS)

    Lee, Byung Wook

    Solid Oxide Fuel Cell (SOFC) has drawn considerable attention for decades due to its high efficiency and low pollution, which is made possible since chemical energy is directly converted to electrical energy through the system without combustion. However, successful commercialization of SOFC has been delayed due to its high production cost mainly related with using high cost of interconnecting materials and the other structural components required for high temperature operation. This is the reason that intermediate (IT) or low temperature (LT)-SOFC operating at 600~800°C or 650°C and below, respectively, is of particular significance because it allows the wider selection of cheaper materials such as stainless steel for interconnects and the other structural components. Also, extended lifetime and system reliability are expected due to less thermal stress through the system with reduced temperature. More rapid start-up/shut-down procedure is another advantage of lowering the operating temperatures. As a result, commercialization of SOFC will be more viable. However, there exists performance drop with reduced operating temperature due to increased polarization resistances from the electrode electrochemical reactions and decreased electrolyte conductivity. Since ohmic polarization of the electrolyte can be significantly reduced with state-of-the art thin film technology and cathode polarization has more drastic effect on total SOFC electrochemical performance than anode polarization as temperature decreases, development of the cathode with high performance operating at IT or LT range is thus essential. On the other hand, chemical stability of the cathode and its chemical compatibility with the electrolyte should also be considered for cathode development since instability and incompatibility of the cathode will also cause substantial performance loss. Based on requirements of the cathode mentioned above, in this study, several chemico-physical approaches were

  1. PROGRESS IN HIGH-TEMPERATURE ELECTROLYSIS FOR HYDROGEN PRODUCTION USING PLANAR SOFC TECHNOLOGY

    SciTech Connect

    O'Brien, J. E.; Herring, J. S.; Stoots, C. M.; Hawkes, G. L.; Hartvigsen, J., J.; Mehrdad Shahnam

    2005-04-01

    A research program is under way at the Idaho National Laboratory to assess the performance of solid-oxide cells operating in the steam electrolysis mode for hydrogen production over a temperature range of 800 to 900ºC. The research program includes both experimental and modeling activities. Selected results from both activities are presented in this paper. Experimental results were obtained from a ten-cell planar electrolysis stack, fabricated by Ceramatec , Inc. The electrolysis cells are electrolyte-supported, with scandia-stabilized zirconia electrolytes (~140 µm thick), nickel-cermet steam/hydrogen electrodes, and manganite air-side electrodes. The metallic interconnect plates are fabricated from ferritic stainless steel. The experiments were performed over a range of steam inlet mole fractions (0.1 - 0.6), gas flow rates (1000 - 4000 sccm), and current densities (0 to 0.38 A/cm2). Hydrogen production rates up to 90 Normal liters per hour were demonstrated. Stack performance is shown to be dependent on inlet steam flow rate. A three-dimensional computational fluid dynamics (CFD) model was also created to model high-temperature steam electrolysis in a planar solid oxide electrolysis cell (SOEC). The model represents a single cell as it would exist in the experimental electrolysis stack. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT1. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Mean model results are shown to compare favorably with

  2. Tailoring Fe-Base Alloys for Intermediate Temperature SOFC Interconnect Application

    SciTech Connect

    J.H. Zhu; M.P. Brady; H.U. Anderson

    2007-12-31

    This report summarized the research efforts and major conclusions for our SECA Phase I and II project focused on Cr-free or low Cr Fe-Ni based alloy development for intermediate temperature solid oxide fuel cell (SOFC) interconnect application. Electrical conductivity measurement on bulk (Fe,Ni){sub 3}O{sub 4} coupons indicated that this spinel phase possessed a higher electrical conductivity than Cr{sub 1.5}Mn{sub 1.5}O{sub 4} spinel and Cr{sub 2}O{sub 3}, which was consistent with the low area specific resistance (ASR) of the oxide scale formed on these Fe-Ni based alloys. For Cr-free Fe-Ni binary alloys, although the increase in Ni content in the alloys improved the oxidation resistance, and the Fe-Ni binary alloys exhibited adequate CTE and oxide scale ASR, their oxidation resistance needs to be further improved. Systematic alloy design efforts have led to the identification of one low-Cr (6wt.%) Fe-Ni-Co based alloy which formed a protective, electrically-conductive Cr{sub 2}O{sub 3} inner layer underneath a Cr-free, highly conductive spinel outer layer. This low-Cr, Fe-Ni-Co alloy has demonstrated a good CTE match with other cell components; high oxidation resistance comparable to that of Crofer; low oxide scale ASR with the formation of electrically-insulating phases in the oxide scale; no scale spallation during thermal cycling; adequate compatibility with cathode materials; and comparable mechanical properties with Crofer. The existence of the Cr-free (Fe,Co,Ni){sub 3}O{sub 4} outer layer effectively reduced the Cr evaporation and in transpiration testing resulted in a 6-fold decrease in Cr evaporation as compared to a state-of-the-art ferritic interconnect alloy. In-cell testing using an anode supported cell with a configuration of Alloy/Pt/LSM/YSZ/Ni+YSZ indicates that the formation of the Cr-free spinel layer via thermal oxidation was effective in blocking the Cr migration and thus improving the cell performance stability. Electroplating of the Fe

  3. Electro-catalytically Active, High Surface Area Cathodes for Low Temperature SOFCs

    SciTech Connect

    Eric D. Wachsman

    2006-09-30

    This research focused on developing low polarization (area specific resistance, ASR) cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs). In order to accomplish this we focused on two aspects of cathode development: (1) development of novel materials; and (2) developing the relationships between microstructure and electrochemical performance. The materials investigated ranged from Ag-bismuth oxide composites (which had the lowest reported ASR at the beginning of this contract) to a series of pyrochlore structured ruthenates (Bi{sub 2-x}M{sub x}Ru{sub 2}O{sub 7}, where M = Sr, Ca, Ag; Pb{sub 2}Ru{sub 2}O{sub 6.5}; and Y{sub 2-2x}Pr{sub 2x}Ru{sub 2}O{sub 7}), to composites of the pyrochlore ruthenates with bismuth oxide. To understand the role of microstructure on electrochemical performance, we optimized the Ag-bismuth oxide and the ruthenate-bismuth oxide composites in terms of both two-phase composition and particle size/microstructure. We further investigated the role of thickness and current collector on ASR. Finally, we investigated issues of stability and found the materials investigated did not form deleterious phases at the cathode/electrolyte interface. Further, we established the ability through particle size modification to limit microstructural decay, thus, enhancing stability. The resulting Ag-Bi{sub 0.8}Er{sub 0.2}O{sub 1.5} and Bi{sub 2}Ru{sub 2}O{sub 7{sup -}}Bi{sub 0.8}Er{sub 0.2}O{sub 1.5} composite cathodes had ASRs of 1.0 {Omega} cm{sup 2} and 0.73 {Omega}cm{sup 2} at 500 C and 0.048 {Omega}cm{sup 2} and 0.053 {Omega}cm{sup 2} at 650 C, respectively. These ASRs are truly impressive and makes them among the lowest IT-SOFC ASRs reported to date.

  4. Long-term commitment of Japanese gas utilities to PAFCs and SOFCs

    NASA Astrophysics Data System (ADS)

    Matsumoto, Kiyokazu; Kasahara, Komei

    Tokyo Gas and Osaka Gas have been committed to addressing the energy- and environment-related issues of Japan through promotion of natural gas, an energy friendly to the environment. Being aware of the diversifying market needs (e.g. efficient energy utilization, rising demand for electricity, etc.), active efforts have been made in marketing gas-fired air-conditioning and co-generation systems. In this process, a high priority has also been placed on fuel cells, particularly for realizing their market introduction. Since their participation in the TARGET Program in USA in 1972, the two companies have been involved with the field testing and operation of phosphoric acid fuel cells (PAFCs), whose total capacity has amounted to 12.4 MW. The two companies have played a vital role in promoting and accelerating fuel cell development through the following means: (1) giving incentives to manufacturers through purchase of units and testing, (2) giving feedback on required specifications and technical problems in operation, and (3) verifying and realizing long-term operation utilizing their maintenance techniques. It has been expected that the primary goal of the cumulative operation time of 40 000 h shall be achieved in the near future. Work has also been in progress to develop SOFC. In the joint R&D of a 25-kW solid oxide fuel cell (SOFC) with Westinghouse, the record operation time of 13 000 h has been achieved. Though still twice as much as the average price of competing equipment, the commercialization of PAFCs is close at hand. By utilizing government spending and subsidies for field testing, work will be continued to verify reliability and durability of PAFCs installed at users' sites. These activities have been expected to contribute to realizing economically viable systems and enhance market introduction. The superlative advantages of fuel cells, particularly their environment-friendly qualities, should be best taken advantage of at an appropriate time. In

  5. 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.

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

    PubMed

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

    2016-09-01

    Pathological features in Alzheimer's brains include mitochondrial dysfunction and dystrophic neurites (DNs) in areas surrounding amyloid plaques. Using a mouse model that overexpresses reticulon 3 (RTN3) and spontaneously develops age-dependent hippocampal DNs, here we report that DNs contain both RTN3 and REEPs, topologically similar proteins that can shape tubular endoplasmic reticulum (ER). Importantly, ultrastructural examinations of such DNs revealed gradual accumulation of tubular ER in axonal termini, and such abnormal tubular ER inclusion is found in areas surrounding amyloid plaques in biopsy samples from Alzheimer's disease (AD) brains. Functionally, abnormally clustered tubular ER induces enhanced mitochondrial fission in the early stages of DN formation and eventual mitochondrial degeneration at later stages. Furthermore, such DNs are abrogated when RTN3 is ablated in aging and AD mouse models. Hence, abnormally clustered tubular ER can be pathogenic in brain regions: disrupting mitochondrial integrity, inducing DNs formation and impairing cognitive function in AD and aging brains. PMID:26619807

  7. Hyperammonemia in distal renal tubular acidosis: is it more common than we think?

    PubMed

    Pela, I; Seracini, D

    2007-08-01

    The hyperammonemia in distal renal tubular acidosis, previously only described in two cases, is considered an unusual occurrence. After the report published in 2005, we observed plasma ammonia levels above normal range during metabolic decompensation in two other consecutive pediatric patients suffering from distal renal tubular acidosis. The ammonia plasma levels returned to normal range after treatment with sodium bicarbonate and potassium salt. In distal renal tubular acidosis, hyperammonemia is probably the result of an imbalance between the increased ammonia synthesis, in response to metabolic acidosis, and the impaired ammonia excretion, typical of distal renal tubular acidosis. According to this physiopathological mechanism, our observation shows that hyperammonemia is not an uncommon finding in distal renal tubular acidosis, and should be included among differential diagnosis of hyperammonemia in infants and children. PMID:17722711

  8. Efficiency of sunlight utilization: tubular versus flat photobioreactors

    PubMed

    Tredici; Zittelli

    1998-01-20

    The light saturation effect imposes a serious limitation on the efficiency with which solar energy can be utilized in outdoor algal cultures. One solution proposed to reduce the intensity of incident solar radiation and overcome the light saturation effect is "spatial dilution of light" (i.e., distribution of the impinging photon flux on a greater photosynthetic surface area), but consistent experimental data supporting a significant positive influence of spatial light dilution on the productivity and the photosynthetic efficiency of outdoor algal cultures have never been reported. We used a coiled tubular reactor and compared a near-horizontal straight tubular reactor and a near-horizontal flat panel in outdoor cultivation of the cyanobacterium Arthrospira (Spirulina) platensis under defined operating conditions for optimum productivity. The photosynthetic efficiency achieved in the tubular systems was significantly higher because their curved surface "diluted" the impinging solar radiation and thus reduced the light saturation effect. This interpretation was supported by the results of experiments carried out in the laboratory under continuous artificial illumination using both a flat and a curved chamber reactor. The study also showed that, when the effect of light saturation is eliminated or reduced, productivity and solar irradiance are linearly correlated even at very high diurnal irradiance values, and supported findings that outdoor algal cultures are light-limited even during bright summer days. It was also observed that, besides improving the photosynthetic efficiency of the culture, spatial dilution of light also leads to higher growth rates and lowers the cellular content of accessory pigments; that is, it reduces mutual shading in the culture. The inadequacy of using volumetric productivity as the sole criterion for comparing reactors of different surface-to-volume ratio and of the areal productivity for evaluating the performance of elevated

  9. Albumin-induced apoptosis of tubular cells is modulated by BASP1.

    PubMed

    Sanchez-Niño, M D; Fernandez-Fernandez, B; Perez-Gomez, M V; Poveda, J; Sanz, A B; Cannata-Ortiz, P; Ruiz-Ortega, M; Egido, J; Selgas, R; Ortiz, A

    2015-02-12

    Albuminuria promotes tubular injury and cell death, and is associated with faster progression of chronic kidney disease (CKD) to end-stage renal disease. However, the molecular mechanisms regulating tubular cell death in response to albuminuria are not fully understood. Brain abundant signal protein 1 (BASP1) was recently shown to mediate glucose-induced apoptosis in tubular cells. We have studied the role of BASP1 in albumin-induced tubular cell death. BASP1 expression was studied in experimental puromycin aminonucleoside-induced nephrotic syndrome in rats and in human nephrotic syndrome. The role of BASP1 in albumin-induced apoptosis was studied in cultured human HK2 proximal tubular epithelial cells. Puromycin aminonucleoside induced proteinuria and increased total kidney BASP1 mRNA and protein expression. Immunohistochemistry localized the increased BASP1 to tubular cells. BASP1 expression colocalized with deoxynucleotidyl-transferase-mediated dUTP nick-end labeling staining for apoptotic cells. Increased tubular BASP1 expression was observed in human proteinuric nephropathy by immunohistochemistry, providing evidence for potential clinical relevance. In cultured tubular cells, albumin induced apoptosis and increased BASP1 mRNA and protein expression at 6-48 h. Confocal microscopy localized the increased BASP1 expression in albumin-treated cells mainly to the perinuclear area. A peripheral location near the cell membrane was more conspicuous in albumin-treated apoptotic cells, where it colocalized with actin. Inhibition of BASP1 expression by a BASP1 siRNA protected from albumin-induced apoptosis. In conclusion, albumin-induced apoptosis in tubular cells is BASP1-dependent. This information may be used to design novel therapeutic approaches to slow CKD progression based on protection of tubular cells from the adverse consequences of albuminuria.

  10. A phase of liposomes with entangled tubular vesicles

    SciTech Connect

    Chiruvolu, S.; Naranjo, E.; Warriner, H.E.; Idziak, S.H.J.; Raedler, J.O.; Zasadzinski, J.A.; Safinya, C.R.; Plano, R.J.

    1994-11-18

    An equilibrium phase belonging to the family of bilayer liposomes in ternary mixtures of dimyristoylphosphatidylcholine (DMPC), water, and geraniol (a biological alcohol derived from oil-soluble vitamins that acts as a cosurfactant) has been identified. Electron and optical microscopy reveal the phase, labeled L{sub tv}, to be composed of highly entangled tubular vesicles. In situ x-ray diffraction confirms that the tubule walls are multilamellar with the lipids in the chain-melted state. Macroscopic observations show that the L{sub tv} phase coexists with the well-known L{sub 4} phase of spherical vesicles and a bulk L{sub {alpha}} phase. However, the defining characteristic of the L{sub tv} phase is the Weissenberg rod climbing effect under shear, which results from its polymer-like entangled microstructure. 26 refs., 5 figs.

  11. Highly aspherical silica nanoshells by templating tubular liposomes

    PubMed Central

    Tan, Grace; Xu, Peng; He, Jibao; Lawson, Louise; McPherson, Gary L.

    2010-01-01

    A dual-lipid liposome system consisting of a phospholipid and a skin ceramide extruded though a 100 nm membrane yields novel tubular and helical liposomes. These liposomes were used as templates to generate highly aspherical silica nanocapsules with length to diameter aspect ratios exceeding 10. Many of these nanocapsules have the morphology of a bulbous end attached to a long tip, mimicking microneedles attached to a reservoir. The fidelity of helical liposomes is transcribed to the silicas and the long tips indicate helically entwined left-handed silica structures. The silica coating is expected to protect and stabilize the internal contents of the liposomes, as well as enable surface functionalization for applications in drug or targeted delivery. PMID:20352059

  12. 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.

  13. [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.

  14. 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.

  15. 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.

  16. Detecting tubular structures via direct vector field singularity characterization.

    PubMed

    Cabuk, Aytekin D; Alpay, Erdenay; Acar, Burak

    2010-01-01

    The initial step of vessel segmentation in 3D is the detection of vessel centerlines. The proposed methods in literature are either dependent on vessel radius and/or have low response at vessel bifurcations. In this paper we propose a 3D tubular structure detection method that removes these two drawbacks. The proposed method exploits the observations on the eigenvalues of the Hessian matrix as is done in literature, yet it employs a direct 3D vector field singularity characterization. The Gradient Vector Flow vector field is used and the eigenvalues of its Jacobian are exploited in computing a parameter free vesselness map. Results on phantom and real patient data exhibit robustness to scale, high response at vessel bifurcations, and good noise/non-vessel structure suppression.

  17. Hot Spots Conjecture and Its Application to Modeling Tubular Structures

    PubMed Central

    Chung, Moo K.; Seo, Seongho; Adluru, Nagesh; Vorperian, Houri K.

    2016-01-01

    The second eigenfunction of the Laplace-Beltrami operator follows the pattern of the overall shape of an object. This geometric property is well known and used for various applications including mesh processing, feature extraction, manifold learning, data embedding and the minimum linear arrangement problem. Surprisingly, this geometric property has not been mathematically formulated yet. This problem is directly related to the somewhat obscure hot spots conjecture in differential geometry. The aim of the paper is to raise the awareness of this nontrivial issue and formulate the problem more concretely. As an application, we show how the second eigenfunction alone can be used for complex shape modeling of tubular structures such as the human mandible.

  18. Urinary Markers of Tubular Injury in HIV-Infected Patients

    PubMed Central

    Gebreweld, Angesom

    2016-01-01

    Renal disease is a common complication of HIV-infected patients, associated with increased risk of cardiovascular events, progression to AIDS, AIDS-defining illness, and mortality. Early and accurate identification of renal disease is therefore crucial to improve patient outcomes. The use of serum creatinine, along with proteinuria, to detect renal involvement is essentially to screen for markers of glomerular disease and may not be effective in detecting earlier stages of renal injury. Therefore, more sensitive and specific markers are needed in order to early identify HIV-infected patients at risk of renal disease. This review article summarizes some new and important urinary markers of tubular injury in HIV-infected patients and their clinical usefulness in the renal safety follow-up of TDF-treated patients. PMID:27493802

  19. Mathematical Modeling of Renal Tubular Glucose Absorption after Glucose Load

    PubMed Central

    De Gaetano, Andrea; Panunzi, Simona; Eliopoulos, Dimitris; Hardy, Thomas; Mingrone, Geltrude

    2014-01-01

    A partial differential Progressive Tubular Reabsorption (PTR) model, describing renal tubular glucose reabsorption and urinary glucose excretion following a glucose load perturbation, is proposed and fitted to experimental data from five subjects. For each subject the Glomerular Filtration Rate was estimated and both blood and urine glucose were sampled following an Intra-Venous glucose bolus. The PTR model was compared with a model representing the conventional Renal Threshold Hypothesis (RTH). A delay bladder compartment was introduced in both formulations. For the RTH model, the average threshold for glycosuria varied between 9.90±4.50 mmol/L and 10.63±3.64 mmol/L (mean ± Standard Deviation) under different hypotheses; the corresponding average maximal transport rates varied between 0.48±0.45 mmol/min (86.29±81.22 mg/min) and 0.50±0.42 mmol/min (90.62±76.15 mg/min). For the PTR Model, the average maximal transports rates varied between 0.61±0.52 mmol/min (109.57±93.77 mg/min) and 0.83±0.95 mmol/min (150.13±171.85 mg/min). The time spent by glucose inside the tubules before entering the bladder compartment varied between 1.66±0.73 min and 2.45±1.01 min. The PTR model proved much better than RTH at fitting observations, by correctly reproducing the delay of variations of glycosuria with respect to the driving glycemia, and by predicting non-zero urinary glucose elimination at low glycemias. This model is useful when studying both transients and steady-state glucose elimination as well as in assessing drug-related changes in renal glucose excretion. PMID:24489817

  20. New Autophagy Reporter Mice Reveal Dynamics of Proximal Tubular Autophagy

    PubMed Central

    Li, Ling; Wang, Zhao V.

    2014-01-01

    The accumulation of autophagosomes in postischemic kidneys may be renoprotective, but whether this accumulation results from the induction of autophagy or from obstruction within the autophagic process is unknown. Utilizing the differential pH sensitivities of red fluorescent protein (RFP; pKa 4.5) and enhanced green fluorescent protein (EGFP; pKa 5.9), we generated CAG-RFP-EGFP-LC3 mice to distinguish early autophagic vacuoles from autolysosomes. In vitro and in vivo studies confirmed that in response to nutrient deprivation, renal epithelial cells in CAG-RFP-EGFP-LC3 mice produce autophagic vacuoles expressing RFP and EGFP puncta. EGFP fluorescence diminished substantially in the acidic environment of the autolysosomes, whereas bright RFP signals remained. Under normal conditions, nephrons expressed few EGFP and RFP puncta, but ischemia-reperfusion injury (IRI) led to dynamic changes in the proximal tubules, with increased numbers of RFP and EGFP puncta that peaked at 1 day after IRI. The number of EGFP puncta returned to control levels at 3 days after IRI, whereas the high levels of RFP puncta persisted, indicating autophagy initiation at day 1 and autophagosome clearance during renal recovery at day 3. Notably, proliferation decreased in cells containing RFP puncta, suggesting that autophagic cells are less likely to divide for tubular repair. Furthermore, 87% of proximal tubular cells with activated mechanistic target of rapamycin (mTOR), which prevents autophagy, contained no RFP puncta. Conversely, inhibition of mTOR complex 1 induced RFP and EGFP expression and decreased cell proliferation. In summary, our results highlight the dynamic regulation of autophagy in postischemic kidneys and suggest a role of mTOR in autophagy resolution during renal repair. PMID:24179166

  1. 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.

  2. 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

  3. Modelling system efficiencies and costs of two biomass-fuelled SOFC systems

    NASA Astrophysics Data System (ADS)

    Omosun, A. O.; Bauen, A.; Brandon, N. P.; Adjiman, C. S.; Hart, D.

    Increasing demand for power and the depletion of fossil fuels are providing opportunities for the development of fuel cells as power generating systems. This paper investigates the integration of a solid oxide fuel cell (SOFC) with biomass gasification for the production of power and heat (combined heat and power (CHP) system). A steady-state model was developed in the gPROMS modelling tool to investigate the integrated system. The system was modelled for two different options, a cold process involving gas cleaning at a reduced temperature and a hot process involving gas cleaning at a high temperature. For each option, the model was used to determine the system efficiency and prospective costs. The electrical efficiency and overall system efficiency for the hot process were found to be 23 and 60% and for the cold process the efficiencies were 21 and 34%, respectively. Superior heat management in the gas cleaning stage of the hot process results in its higher system efficiency. The capital cost for the hot process appears higher than that for the cold process. This differential capital cost may be justified by the income earned from selling the extra heat produced in the hot process. Conversely, the cold process produces a gas stream with lower levels of impurities than the hot process.

  4. Electrodeposition of Mn-Co Alloys on Stainless Steels for SOFC Interconnect Application

    SciTech Connect

    Wu, J.; Jiang, Y.; Johnson, C.; Gong, M.; Liu, X.

    2007-09-01

    Chromium-containing ferritic stainless steels are the most popular materials for solid oxide fuel cell (SOFC) interconnect applications because of its oxidation resistance and easy fabrication process. However, excessive scale growth and chromium evaporation will degrade the cell performance. Highly conductive coatings that resist oxide scale growth and chromium evaporation may prevent both of these problems. Mn1.5Co1.5O4 spinel is one of the most promising coatings for interconnect application because of its high conducitivy, good chromium retention capability, as well as good CTE match. Electroplating of alloys or thin film multilayers followed by controlled oxidation to the desired spinel phase offers an additional deposition option. In the present study binary Mn/Co alloys was fabricated by electrodeposition, and polarization curves were used to characterize the cathodic reactions on substrate surface. By controlling the current density precisely, coatings with Mn/Co around 1:1 has been successfully deposited in Mn/Co =10 solutions, SEM and EDX was used to characterize the surface morphology and composition.

  5. Enhancement of SOFC Cathode Electrochemical Performance Using Multi-Phase Interfaces

    SciTech Connect

    Morgan, Dane

    2015-09-30

    This work explored the use of oxide heterostructures for enhancing the catalytic and degradation properties of solid oxide fuel cell (SOFC) cathode electrodes. We focused on heterostructures of Ruddlesden-Popper and perovskite phases. Building on previous work showing enhancement of the Ruddlesden-Popper (La,Sr)2CoO4 / perovskite (La,Sr)CoO3 heterostructure compared to pure (La,Sr)CoO3 we explored the application of related heterostructures of Ruddlesden-Popper phases on perovskite (La,Sr)(Co,Fe)O3. Our approaches included thin-film electrodes, physical and electrochemical characterization, elementary reaction kinetics modeling, and ab initio simulations. We demonstrated that Sr segregation to surfaces is likely playing a critical role in the performance of (La,Sr)CoO3 and (La,Sr)(Co,Fe)O3 and that modification of this Sr segregation may be the mechanism by which Ruddlesden-Popper coatings enhance performances. We determined that (La,Sr)(Co,Fe)O3 could be enhanced in thin films by about 10× by forming a heterostructure simultaneously with (La,Sr)2CoO4 and (La,Sr)CoO3. We hope that future work will develop this heterostructure for use as a bulk porous electrode.

  6. Small Scale SOFC Demonstration Using Bio-Based and Fossil Fuels

    SciTech Connect

    Petrik, Michael; Ruhl, Robert

    2012-05-01

    Technology Management, Inc. (TMI) of Cleveland, Ohio, has completed the project entitled Small Scale SOFC Demonstration using Bio-based and Fossil Fuels. Under this program, two 1-kW systems were engineered as technology demonstrators of an advanced technology that can operate on either traditional hydrocarbon fuels or renewable biofuels. The systems were demonstrated at Patterson's Fruit Farm of Chesterland, OH and were open to the public during the first quarter of 2012. As a result of the demonstration, TMI received quantitative feedback on operation of the systems as well as qualitative assessments from customers. Based on the test results, TMI believes that > 30% net electrical efficiency at 1 kW on both traditional and renewable fuels with a reasonable entry price is obtainable. The demonstration and analysis provide the confidence that a 1 kW entry-level system offers a viable value proposition, but additional modifications are warranted to reduce sound and increase reliability before full commercial acceptance.

  7. Analyses of microstructural and elastic properties of porous SOFC cathodes based on focused ion beam tomography

    NASA Astrophysics Data System (ADS)

    Chen, Zhangwei; Wang, Xin; Giuliani, Finn; Atkinson, Alan

    2015-01-01

    Mechanical properties of porous SOFC electrodes are largely determined by their microstructures. Measurements of the elastic properties and microstructural parameters can be achieved by modelling of the digitally reconstructed 3D volumes based on the real electrode microstructures. However, the reliability of such measurements is greatly dependent on the processing of raw images acquired for reconstruction. In this work, the actual microstructures of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathodes sintered at an elevated temperature were reconstructed based on dual-beam FIB/SEM tomography. Key microstructural and elastic parameters were estimated and correlated. Analyses of their sensitivity to the grayscale threshold value applied in the image segmentation were performed. The important microstructural parameters included porosity, tortuosity, specific surface area, particle and pore size distributions, and inter-particle neck size distribution, which may have varying extent of effect on the elastic properties simulated from the microstructures using FEM. Results showed that different threshold value range would result in different degree of sensitivity for a specific parameter. The estimated porosity and tortuosity were more sensitive than surface area to volume ratio. Pore and neck size were found to be less sensitive than particle size. Results also showed that the modulus was essentially sensitive to the porosity which was largely controlled by the threshold value.

  8. Tubular up-regulation of clusterin mRNA in murine lupus-like nephritis.

    PubMed Central

    Moll, S.; Menoud, P. A.; French, L.; Sappino, A. P.; Pastore, Y.; Schifferli, J. A.; Izui, S.

    1998-01-01

    Clusterin, a widely distributed glycoprotein, is detected in most tissues and in numerous physiological fluids. In the kidney, this protein is constitutively expressed in tubular epithelial cells, and its expression is enhanced following tubular injuries. In addition, clusterin has been detected in glomerular immune deposits of glomerulonephritis. The present study was designed to define the sites of clusterin mRNA accumulation in murine lupus-like nephritis in comparison with murine tubulopathies. In lupus-like nephritis, a significant increase of clusterin mRNA abundance was demonstrated. This up-regulation was localized exclusively in tubular epithelial cells exhibiting tubulointerstitial alterations, whereas no clusterin mRNA was detectable in diseased glomeruli, excluding an active synthesis of clusterin by glomerular cells. A similar tubular increase of clusterin mRNA abundance was observed in myeloma-like cast nephropathy induced by IgG3 monoclonal cryoglobulins and even in the absence of any detectable histological alterations in a model of septic shock induced by the injection of bacterial lipopolysaccharides. Our results suggest that tubular epithelial cells are the only sites of clusterin mRNA accumulation during the course of lupus-like nephritis and that the tubular up-regulation of clusterin gene expression may reflect the cellular response to various types of tubular injuries. Images Figure 1 Figure 3 Figure 4 Figure 5 Figure 7 PMID:9546356

  9. Nephrotic syndrome and multiple tubular defects in children: an early sign of focal segmental glomerulosclerosis.

    PubMed

    McVicar, M; Exeni, R; Susin, M

    1980-12-01

    The nephrotic syndrome is rarely associated with renal tubular defects, and the combination has been reported only in association with advanced renal insufficiency. We report here five children with nephrotic syndrome and multiple tubular defects which evolved when glomular filtration rate ranged between 56 and 90 ml/minute/1.73 m2. The tubular defects were first noted at 3, 4, 4, 7, and 22 months after the onset of the nephrotic syndrome, and renal glycosuria was the first sign in all five children. Glycosuria was intermittent in three patients, constant in two, and ceased with loss of kidney function. Four patients had hyperaminoaciduria and renal tubular acidosis (two of four tested had distal renal tubular acidosis). Three patients had decreased tubular reabsorption of phosphorus and defective maximum concentrating capacity. All five had focal segmental glomerulosclerosis proven by renal biopsy. Over a follow-up period of seven years, all of the children have developed advanced renal insufficiency, four of the five have required dialysis or transplantation within 21 to 72 months after onset, and one has stabilized renal function at 35 ml/minute/1.73 m2. The one patient receiving a kidney transplant has had recurrence of focal segmental glomerulosclerosis in the transplanted kidney and became nephrotic with three subsequent transplants. Our experience suggests that the nephrotic syndrome associated with tubular defects in children forms a subgroup of focal segmental glomerulosclerosis, with rapid progression to renal insufficiency and the potential for recurrence of the lesion in the transplanted kidney.

  10. Tubular up-regulation of clusterin mRNA in murine lupus-like nephritis.

    PubMed

    Moll, S; Menoud, P A; French, L; Sappino, A P; Pastore, Y; Schifferli, J A; Izui, S

    1998-04-01

    Clusterin, a widely distributed glycoprotein, is detected in most tissues and in numerous physiological fluids. In the kidney, this protein is constitutively expressed in tubular epithelial cells, and its expression is enhanced following tubular injuries. In addition, clusterin has been detected in glomerular immune deposits of glomerulonephritis. The present study was designed to define the sites of clusterin mRNA accumulation in murine lupus-like nephritis in comparison with murine tubulopathies. In lupus-like nephritis, a significant increase of clusterin mRNA abundance was demonstrated. This up-regulation was localized exclusively in tubular epithelial cells exhibiting tubulointerstitial alterations, whereas no clusterin mRNA was detectable in diseased glomeruli, excluding an active synthesis of clusterin by glomerular cells. A similar tubular increase of clusterin mRNA abundance was observed in myeloma-like cast nephropathy induced by IgG3 monoclonal cryoglobulins and even in the absence of any detectable histological alterations in a model of septic shock induced by the injection of bacterial lipopolysaccharides. Our results suggest that tubular epithelial cells are the only sites of clusterin mRNA accumulation during the course of lupus-like nephritis and that the tubular up-regulation of clusterin gene expression may reflect the cellular response to various types of tubular injuries.

  11. 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.

  12. 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. PMID:27190368

  13. Chemistry of SOFC Cathode Surfaces: Fundamental Investigation and Tailoring of Electronic Behavior

    SciTech Connect

    Yildiz, Bilge; Heski, Clemens

    2013-08-31

    1) Electron tunneling characteristics on La0.7Sr0.3MnO3 (LSM) thin-film surfaces were studied up to 580oC in 10-3mbar oxygen pressure, using scanning tunneling microscopy/ spectroscopy (STM/STS). A threshold-like drop in the tunneling current was observed at positive bias in STS, which is interpreted as a unique indicator for the activation polarization in cation oxygen bonding on LSM cathodes. Sr-enrichment was found on the surface at high temperature using Auger electron spectroscopy, and was accompanied by a decrease in tunneling conductance in STS. This suggests that Sr-terminated surfaces are less active for electron transfer in oxygen reduction compared to Mn-terminated surfaces on LSM. 2) Effects of strain on the surface cation chemistry and the electronic structure are important to understand and control for attaining fast oxygen reduction kinetics on transition metal oxides. Here, we demonstrate and mechanistically interpret the strain coupling to Sr segregation, oxygen vacancy formation, and electronic structure on the surface of La0.7Sr0.3MnO3 (LSM) thin films as a model system. Our experimental results from x-ray photoelectron spectroscopy and scanning tunneling spectroscopy are discussed in light of our first principles-based calculations. A stronger Sr enrichment tendency and a more facile oxygen vacancy formation prevail for the tensile strained LSM surface. The electronic structure of the tensile strained LSM surface exhibits a larger band gap at room temperature, however, a higher tunneling conductance near the Fermi level than the compressively strained LSM at elevated temperatures in oxygen. Our findings suggest lattice strain as a key parameter to tune the reactivity of perovskite transition metal oxides with oxygen in solid oxide fuel cell cathodes. 3) Cation segregation on perovskite oxide surfaces affects vastly the oxygen reduction activity and stability of solid oxide fuel cell (SOFC) cathodes. A unified theory that explains the physical

  14. Determination of Electrochemical Performance and Thermo-Mechanical-Chemical Stability of SOFCs from Defect Modeling

    SciTech Connect

    Eric Wachsman; Keith L. Duncan

    2006-09-30

    This research was focused on two distinct but related issues. The first issue concerned using defect modeling to understand the relationship between point defect concentration and the electrochemical, thermo-chemical and mechano-chemical properties of typical solid oxide fuel cell (SOFC) materials. The second concerned developing relationships between the microstructural features of SOFC materials and their electrochemical performance. To understand the role point defects play in ceramics, a coherent analytical framework was used to develop expressions for the dependence of thermal expansion and elastic modulus on point defect concentration in ceramics. These models, collectively termed the continuum-level electrochemical model (CLEM), were validated through fits to experimental data from electrical conductivity, I-V characteristics, elastic modulus and thermo-chemical expansion experiments for (nominally pure) ceria, gadolinia-doped ceria (GDC) and yttria-stabilized zirconia (YSZ) with consistently good fits. The same values for the material constants were used in all of the fits, further validating our approach. As predicted by the continuum-level electrochemical model, the results reveal that the concentration of defects has a significant effect on the physical properties of ceramic materials and related devices. Specifically, for pure ceria and GDC, the elastic modulus decreased while the chemical expansion increased considerably in low partial pressures of oxygen. Conversely, the physical properties of YSZ remained insensitive to changes in oxygen partial pressure within the studied range. Again, the findings concurred exactly with the predictions of our analytical model. Indeed, further analysis of the results suggests that an increase in the point defect content weakens the attractive forces between atoms in fluorite-structured oxides. The reduction treatment effects on the flexural strength and the fracture toughness of pure ceria were also evaluated at

  15. Feasibility study and techno-economic analysis of an SOFC/battery hybrid system for vehicle applications

    NASA Astrophysics Data System (ADS)

    Aguiar, P.; Brett, D. J. L.; Brandon, N. P.

    A feasibility study and techno-economic analysis for a hybrid power system intended for vehicular traction applications has been performed. The hybrid consists of an intermediate temperature solid oxide fuel cell (IT-SOFC) operating at 500-800 °C and a sodium-nickel chloride (ZEBRA) battery operating at 300 °C. Such a hybrid system has the benefits of extended range and fuel flexibility (due to the IT-SOFC), high power output and rapid response time (due to the battery). The above hybrid has been compared to a fuel cell-only, a battery-only and an ICE vehicle. It is shown that the capital cost associated with a fuel cell-only vehicle is still much higher than that of any other power source option and that a battery-only option would potentially encounter weight and volume limitations, particularly for long drive times. It is concluded that increasing drive time per day decreases substantially the payback time in relation to an ICE vehicle running on gasoline and thus that the hybrid vehicle is an economically attractive option for commercial vehicles with long drive times. In the case where the battery has reached volume production prices at £70 kWh -1 and current fuel duty values remain unchanged then a payback time <2 years is obtained. For a light delivery van operating with 6 h drive time per day, a fuel cell system model predicted a gasoline equivalent fuel economy of 25.1 km L -1, almost twice that of a gasoline fuelled ICE vehicle of the same size, and CO 2 emissions of 71.6 g km -1, well below any new technology target set so far. It is therefore recommended that a SOFC/ZEBRA demonstration be built to further explore its viability.

  16. Evaluation of Binary Fe-Ni Alloys as Intermediate-Temperature SOFC Interconnect

    SciTech Connect

    Zhu, Jiahong; Geng, Shujiang; Lu, Z G; Porter, Wallace D

    2007-01-01

    Binary Fe-Ni alloys with 45-60Ni (wt %) were evaluated as an interconnect material for intermediate-temperature solid oxide fuel cells (SOFCs). The oxidation resistance of the Fe-Ni alloys in air improved with increasing Ni content. The thermally grown oxide scale on these alloys generally consisted of a Fe{sub 2}O{sub 3} top layer and a (Fe,Ni){sub 3}O{sub 4} spinel inner layer, with the thickness of the Fe{sub 2}O{sub 3} layer decreasing as the Ni content increased. No measurable weight change was observed after isothermal oxidation in Ar+4%H{sub 2}+3%H{sub 2}O at 800 C and a metallic surface was maintained. The coefficient of thermal expansion (CTE) increased with the Ni content in these alloys and the CTE values were similar to those of other cell components. The (Fe,Ni){sub 3}O{sub 4} spinel with a composition similar to that thermally grown on the Fe-50Ni alloy exhibited a CTE value close to the alloy substrate, which aids scale spallation resistance for this alloy. The scale area specific resistance of the Fe-Ni alloys was found to be comparable to that of the current interconnect alloys, as a result of high electrical conductivity of the (Fe,Ni){sub 3}O{sub 4} spinel. The promise and issue with these Fe-Ni alloys as interconnect materials are highlighted and potential approaches to address the issue are outlined.

  17. High valence transition metal doped strontium ferrites for electrode materials in symmetrical SOFCs

    NASA Astrophysics Data System (ADS)

    Fernández-Ropero, A. J.; Porras-Vázquez, J. M.; Cabeza, A.; Slater, P. R.; Marrero-López, D.; Losilla, E. R.

    2014-03-01

    In this paper we report the successful incorporation of high valence transition metals, i.e. Cr, Mo, W, V, Nb, Ti, Zr into SrFeO3-δ perovskite materials, for potential applications as symmetric electrode materials for Solid Oxide Fuel Cells. It is observed that the doping leads to a change from an orthorhombic structure (with partial ordering of oxygen vacancies) to a cubic one (with the oxygen vacancies disordered). These electrodes are chemically compatibles with Ce0.9Gd0.1O1.95 (CGO) and La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) electrolytes at least up to 1100 °C. Thermal annealing experiments in 5% H2-Ar at 800 °C also show the stability of the doped samples in reducing conditions, suggesting that they may be suitable for both cathode and anode applications. In contrast, reduction of undoped SrFeO3-δ leads to the observation of extra peaks indicating the formation of the brownmillerite structure with the associated oxygen vacancy ordering. The performance of these electrodes was examined on dense electrolyte pellets of CGO and LSGM in air and 5% H2-Ar. In both atmospheres an improvement in the area specific resistances (ASR) values is observed for the doped samples with respect to the parent compound. Thus, the results show that high valence transition metals can be incorporated into SrFeO3-δ-based materials and can have a beneficial effect on the electrochemical performance, making them potentially suitable for use as cathode and anode materials in symmetrical SOFC.

  18. Oxygen Transport Kinetics in Infiltrated SOFCs Cathode by Electrical Conductivity Relaxation Technique

    SciTech Connect

    Li, Yihong; Gerdes, Kirk; Liu, Xingbo

    2013-07-01

    Infiltration has attracted increasing attention as an effective technique to modify SOFC cathodes to improve cell electrochemical performance while maintaining material compatibility and long-term stability. However, the infiltrated material's effect on oxygen transport is still not clear and detailed knowledge of the oxygen reduction reaction in infiltrated cathodes is lacking. In this work, the technique of electrical conductivity relaxation (ECR) is used to evaluate oxygen exchange in two common infiltrated materials, Ce{sub 0.8}Sm{sub 0.2}O{sub 1.9} and La{sub 0.6}Sr{sub 0.4}CoO{sub 3-δ}. The ECR technique is also used to examine the transport processes in a composite material formed with a backbone of La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3-δ} and possessing a thin, dense surface layer composed of the representative infiltrate material. Both the surface oxygen exchange process and the oxygen exchange coefficient at infiltrate/LSCF interface are reported. ECR testing results indicate that the application of infiltrate under certain oxygen partial pressure conditions produces a measureable increase in the fitted oxygen exchange parameter. It is presently only possible to generate hypotheses to explain the observation. However the correlation between improved electrochemical performance and increased oxygen transport measured by ECR is reliably demonstrated. The simple and inexpensive ECR technique is utilized as a direct method to optimize the selection of specific infiltrate/backbone material systems for superior performance.

  19. A dynamic physics-based model for tubular IPMC sensors under torsional excitation

    NASA Astrophysics Data System (ADS)

    Lei, Hong; Sharif, Montassar Aidi; Tan, Xiaobo

    2016-04-01

    Ionic polymer-metal composites (IPMCs) have intrinsic sensing and actuation properties. An IPMC sensor typically has the beam shape and responds to bending deflections only. Recently tubular IPMCs have been proposed for omnidirectional sensing of bending stimuli. In this paper we report, to our best knowledge, the first study on torsion sensing with tubular IPMCs. In particular, a dynamic, physics-based model is presented for a tubular IPMC sensor under pure torsional stimulus. With the symmetric tubular structure and the pure torsion condition, the stress distribution inside the polymer only varies along the radial direction, resulting in a one-dimensional model. The dynamic model is derived by analytically solving the governing partial differential equation, accommodating the assumed boundary condition that the charge density is proportional to the mechanically induced stress. Experiments are further conducted to estimate the physical parameters of the proposed model.

  20. Automatic centerline extraction of irregular tubular structures using probability volumes from multiphoton imaging.

    PubMed

    Santamaría-Pang, A; Colbert, C M; Saggau, P; Kakadiaris, I A

    2007-01-01

    In this paper, we present a general framework for extracting 3D centerlines from volumetric datasets. Unlike the majority of previous approaches, we do not require a prior segmentation of the volume nor we do assume any particular tubular shape. Centerline extraction is performed using a morphology-guided level set model. Our approach consists of: i) learning the structural patterns of a tubular-like object, and ii) estimating the centerline of a tubular object as the path with minimal cost with respect to outward flux in gray level images. Such shortest path is found by solving the Eikonal equation. We compare the performance of our method with existing approaches in synthetic, CT, and multiphoton 3D images, obtaining substantial improvements, especially in the case of irregular tubular objects. PMID:18044604

  1. 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

  2. Design and analysis of tubular permanent magnet linear wave generator.

    PubMed

    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.

  3. 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.

  4. Steady State Response Analysis of a Tubular Piezoelectric Print Head.

    PubMed

    Chang, Jiaqing; Liu, Yaxin; Huang, Bo

    2016-01-12

    In recent years, inkjet technology has played an important role in industrial materials printing and various sensors fabrication, but the mechanisms of the inkjet print head should be researched more elaborately. The steady state deformation analysis of a tubular piezoelectric print head, which can be classified as a plane strain problem because the radii of the tubes are considerably smaller than the lengths, is discussed in this paper. The geometric structure and the boundary conditions are all axisymmetric, so a one-dimensional mathematical model is constructed. By solving the model, the deformation field and stress field, as well as the electric potential distribution of the piezoelectric tube and glass tube, are obtained. The results show that the deformations are on the nanometer scale, the hoop stress is larger than the radial stress on the whole, and the potential is not linearly distributed along the radial direction. An experiment is designed to validate these computations. A discussion of the effect of the tubes' thicknesses on the system deformation status is provided.

  5. Twisted and tubular silica structures by anionic surfactant fibers encapsulation.

    PubMed

    Chekini, Mahshid; Guénée, Laure; Marchionni, Valentina; Sharma, Manish; Bürgi, Thomas

    2016-09-01

    Organic molecules imprinting can be used for introducing specific properties and functionalities such as chirality to mesoporous materials. Particularly organic self-assemblies can work as a scaffold for templating inorganic materials such as silica. During recent years chiral imprinting of anionic surfactant for fabrication of twisted rod-like silica structures assisted by co-structuring directing agent were thoroughly investigated. The organic self-assemblies of anionic surfactants can also be used for introducing other shapes in rod-like silica structures. Here we report the formation of amphiphilic N-miristoyl-l-alanine self-assemblies in aqueous solution upon stirring and at presence of l-arginine. These anionic surfactant self-assemblies form fibers that grow by increasing the stirring duration. The fibers were studied using transmission electron microscopy, infra-red spectroscopy and vibrational circular dichroism. Addition of silica precursor 1,2-bis(triethoxysilyl)ethylene and co-structuring directing agent N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride at different stages of fibers' growth leads to formation of different silica structures. By controlling stirring duration, we obtained twisted tubular silica structures as a result of fibers encapsulation. We decorated these structures with gold nanoparticles by different methods and measured their optical activity.

  6. Steady State Response Analysis of a Tubular Piezoelectric Print Head.

    PubMed

    Chang, Jiaqing; Liu, Yaxin; Huang, Bo

    2016-01-01

    In recent years, inkjet technology has played an important role in industrial materials printing and various sensors fabrication, but the mechanisms of the inkjet print head should be researched more elaborately. The steady state deformation analysis of a tubular piezoelectric print head, which can be classified as a plane strain problem because the radii of the tubes are considerably smaller than the lengths, is discussed in this paper. The geometric structure and the boundary conditions are all axisymmetric, so a one-dimensional mathematical model is constructed. By solving the model, the deformation field and stress field, as well as the electric potential distribution of the piezoelectric tube and glass tube, are obtained. The results show that the deformations are on the nanometer scale, the hoop stress is larger than the radial stress on the whole, and the potential is not linearly distributed along the radial direction. An experiment is designed to validate these computations. A discussion of the effect of the tubes' thicknesses on the system deformation status is provided. PMID:26771612

  7. 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).

  8. Constructal optimization for a single tubular solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Feng, Huijun; Chen, Lingen; Xie, Zhihui; Sun, Fengrui

    2015-07-01

    Based on constructal theory, the structure of a single tubular solid oxide fuel cell (TSOFC) is optimized in this paper. The maximum power output is chosen as the optimization objective. The optimal constructs of the TSOFC are obtained. The results show that the local power output PE,j and the local current density ij decrease along the flow direction. For the fixed anode, cathode and electrolyte volume fractions, there exist optimal anode, cathode and electrolyte thicknesses as well as the corresponding optimal fuel cell lengths which lead to the maximum power outputs of the TSOFC, respectively. For the fixed inner radius of the solid parts, there exist an optimal cathode thickness and an optimal fuel cell length which lead to the double maximum power output (the power output after twice maximization) of the TSOFC. The power output of the TSOFC after constructal optimization is increased by 18.20% compared to that of the TSOFC with cathode thickness tc = 2200 μm and fuel cell length L = 1.5 m. The performance of the TSOFC is evidently improved by adopting the optimal constructs obtained in this paper.

  9. 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.

  10. 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

  11. Steady State Response Analysis of a Tubular Piezoelectric Print Head

    PubMed Central

    Chang, Jiaqing; Liu, Yaxin; Huang, Bo

    2016-01-01

    In recent years, inkjet technology has played an important role in industrial materials printing and various sensors fabrication, but the mechanisms of the inkjet print head should be researched more elaborately. The steady state deformation analysis of a tubular piezoelectric print head, which can be classified as a plane strain problem because the radii of the tubes are considerably smaller than the lengths, is discussed in this paper. The geometric structure and the boundary conditions are all axisymmetric, so a one-dimensional mathematical model is constructed. By solving the model, the deformation field and stress field, as well as the electric potential distribution of the piezoelectric tube and glass tube, are obtained. The results show that the deformations are on the nanometer scale, the hoop stress is larger than the radial stress on the whole, and the potential is not linearly distributed along the radial direction. An experiment is designed to validate these computations. A discussion of the effect of the tubes’ thicknesses on the system deformation status is provided. PMID:26771612

  12. Etiopathology of chronic tubular, glomerular and renovascular nephropathies: Clinical implications

    PubMed Central

    2011-01-01

    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. PMID:21251296

  13. Evacuated tubular solar collector with internal reflector and heatpipe

    SciTech Connect

    Imani, K.; Ikeda, N.; Sumida, I.

    1983-12-01

    An evacuated tubular solar collector, was developed to provide 130/sup 0/C water for an industrial system. The collector consisted of 6 glass-tubes (100 mm O.D.), the internal silver ion-plated reflector, and copper heatpipes coated by the chrome-black selective absorber. The absorptance and the emittance of the absorber was measured to be 95% and 12%, respectively. The cross-section of reflector was composed of involute curve, straight line and envelope curve. The straight line was used to widen the aperture of reflector, and the envelope curve was designed to focus the 30/sup 0/ incident light on the heatpipe surface. The acceptance angle, concentration ratio and reflectivity was 60/sup 0/, 1.3, and 93%, respectively. The tip of heatpipe, which east side was horizontally 0.7/sup 0/ declined, was bent upwards to accommodate the freezing space to working fluid of 100 cm/sup 3/ water. The west side of heatpipe (22.22 mm O.D.) was connected to the coaxial heat exchanger with the internal fins. The effective colletor area was 1.43 m/sup 2/, while the total installation area was 1.92 m/sup 2/ (2.86m X 0.67m).

  14. Polydopamine as an adhesive coating for open tubular capillary electrochromatography.

    PubMed

    Martma, Kert; Habicht, Kaia-Liisa; Ramirez, Xochitl M; Tepp, Kersti; Käämbre, Tuuli; Volobujeva, Olga; Shimmo, Ruth

    2011-04-01

    Polydopamine (PolyD) coating was used as an adhesive layer in the preparation of biological stationary phases for open tubular capillary electrochromatography (OT-CEC). The influence of coating solution freshness, coating time, temperature and dopamine hydrochloride concentration on the PolyD layer formation was studied. The performance of the polyD coating was monitored by measuring the electro-osmotic flow in coated capillaries. Following polyD coating of the capillary, secondary layer material (e.g. cell membrane solutions, phospholipid mixtures or mitochondria) was inserted into the capillary for at least 1 h. The performance of these double-coated capillaries (a polyD layer+a biological material layer) was compared with capillaries containing the respective biological material directly attached to the capillary wall. The study reveals that the presence of polyD layer in fused silica capillaries improves the performance of lipid and membrane fragment coatings in capillaries. At the same time, the thickness of the polyD layer does not have marked impact on the secondary coatings. Analysis with test analytes demonstrated that double-coated capillaries can be applied to study membrane-drug interactions. PMID:21449069

  15. Gradient-based enhancement of tubular structures in medical images.

    PubMed

    Moreno, Rodrigo; Smedby, Örjan

    2015-12-01

    Vesselness filters aim at enhancing tubular structures in medical images. The most popular vesselness filters are based on eigenanalyses of the Hessian matrix computed at different scales. However, Hessian-based methods have well-known limitations, most of them related to the use of second order derivatives. In this paper, we propose an alternative strategy in which ring-like patterns are sought in the local orientation distribution of the gradient. The method takes advantage of symmetry properties of ring-like patterns in the spherical harmonics domain. For bright vessels, gradients not pointing towards the center are filtered out from every local neighborhood in a first step. The opposite criterion is used for dark vessels. Afterwards, structuredness, evenness and uniformness measurements are computed from the power spectrum in spherical harmonics of both the original and the half-zeroed orientation distribution of the gradient. Finally, the features are combined into a single vesselness measurement. Alternatively, a structure tensor that is suitable for vesselness can be estimated before the analysis in spherical harmonics. The two proposed methods are called Ring Pattern Detector (RPD) and Filtered Structure Tensor (FST) respectively. Experimental results with computed tomography angiography data show that the proposed filters perform better compared to the state-of-the-art.

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

    PubMed Central

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

    2014-01-01

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

  17. A new tubular graphene form of a tetrahedrally connected cellular structure.

    PubMed

    Bi, Hui; Chen, I-Wei; Lin, Tianquan; Huang, Fuqiang

    2015-10-21

    3D architectures constructed from a tubular graphene network can withstand repeated >95% compression cycling without damage. Aided by intertubular covalent bonding, this material takes full advantage of the graphene tube's unique attributes, including complete pre- and post-buckling elasticity, outstanding electrical conductivity, and extraordinary physicochemical stability. A highly connected tubular graphene will thus be the ultimate, structurally robust, ultrastrong, ultralight material. PMID:26305918

  18. [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.

  19. Tubular cell phenotype in HIV-associated nephropathy: role of phospholipid lysophosphatidic acid.

    PubMed

    Ayasolla, Kamesh R; Rai, Partab; Rahimipour, Shai; Hussain, Mohammad; Malhotra, Ashwani; Singhal, Pravin C

    2015-08-01

    Collapsing glomerulopathy and microcysts are characteristic histological features of HIV-associated nephropathy (HIVAN). We have previously reported the role of epithelial mesenchymal transition (EMT) in the development of glomerular and tubular cell phenotypes in HIVAN. Since persistent tubular cell activation of NFκB has been reported in HIVAN, we now hypothesize that HIV may be contributing to tubular cell phenotype via lysophosphatidic acid (LPA) mediated downstream signaling. Interestingly, LPA and its receptors have also been implicated in the tubular interstitial cell fibrosis (TIF) and cyst formation in autosomal dominant polycystic kidney disease (PKD). Primary human proximal tubular cells (HRPTCs) were transduced with either empty vector (EV/HRPTCs), HIV (HIV/HRPTCs) or treated with LPA (LPA/HRPTC). Immunoelectrophoresis of HIV/HRPTCs and LPA/HRPTCs displayed enhanced expression of pro-fibrotic markers: a) fibronectin (2.25 fold), b) connective tissue growth factor (CTGF; 4.8 fold), c) α-smooth muscle actin (α-SMA; 12 fold), and d) collagen I (5.7 fold). HIV enhanced tubular cell phosphorylation of ILK-1, FAK, PI3K, Akt, ERKs and P38 MAPK. HIV increased tubular cell transcriptional binding activity of NF-κB; whereas, a LPA biosynthesis inhibitor (AACOCF3), a DAG kinase inhibitor, a LPA receptor blocker (Ki16425), a NF-κB inhibitor (PDTC) and NFκB-siRNA not only displayed downregulation of a NFκB activity but also showed attenuated expression of profibrotic/EMT genes in HIV milieu. These findings suggest that LPA could be contributing to HIV-induced tubular cell phenotype via NFκB activation in HIVAN. PMID:26079546

  20. Renal tubular function in patients on long-term lithium therapy.

    PubMed

    Viol, G W; Grof, P; Daigle, L

    1975-01-01

    The authors conducted a study in which 10 patients with recurrent affective disorders who responded completely to long-term lithium therapy but who were otherwise unselected were tested for renal tubular concentrating and acidification ability. Despite frequent symptoms of thirst, polyuria, and nocturia, all patients were able to concentrate urine normally and all showed normal renal tubular acidification ability. A significant correlation was found between erythrocyte lithium concentration and maximum urinary osmolality. PMID:45538

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

    PubMed

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

    2015-01-01

    The purpose of this study was to compare the dosimetric properties of small field electron beams shaped by circular Cerrobend blocks and stainless steel tubular applicators. Percentage depth dose curves, beam profiles, and output factors of small-size circular fields from 2 to 5 cm diameter, obtained either by tubular applicators and Cerrobend blocks, were measured for 6, 10, and 15 MeV electron beam energies. All measurements were performed using a PTW microDiamond 60019 premarket prototype. An overall similar behavior between the two collimating systems can be observed in terms of PDD and beam profiles. However, Cerrobend collimators produce a higher bremsstrahlung background under irradiation with high-energy electrons. In such irradiation condition, larger output factors are observed for tubular applicators. Similar dosimetric properties are observed using circular Cerrobend blocks and stainless steel tubular applicators at lower beam energies. However, Cerrobend collimators allow the delivery of specific beam shapes, conformed to the target area. On the other hand, in high-energy irradiation conditions, tubular applicators produce a lower bremsstrahlung contribution, leading to lower doses outside the target volume. In addition, the higher output factors observed at high energies for tubular applicators lead to reduced treatment times. PMID:25679175

  2. 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.

  3. pH measurement of tubular vacuoles of an arbuscular mycorrhizal fungus, Gigaspora margarita.

    PubMed

    Funamoto, Rintaro; Saito, Katsuharu; Oyaizu, Hiroshi; Aono, Toshihiro; Saito, Masanori

    2015-01-01

    Arbuscular mycorrhizal fungi play an important role in phosphate supply to the host plants. The fungal hyphae contain tubular vacuoles where phosphate compounds such as polyphosphate are accumulated. Despite their importance for the phosphate storage, little is known about the physiological properties of the tubular vacuoles in arbuscular mycorrhizal fungi. As an indicator of the physiological state in vacuoles, we measured pH of tubular vacuoles in living hyphae of arbuscular mycorrhizal fungus Gigaspora margarita using ratio image analysis with pH-dependent fluorescent probe, 6-carboxyfluorescein. Fluorescent images of the fine tubular vacuoles were obtained using a laser scanning confocal microscope, which enabled calculation of vacuolar pH with high spatial resolution. The tubular vacuoles showed mean pH of 5.6 and a pH range of 5.1-6.3. These results suggest that the tubular vacuoles of arbuscular mycorrhizal fungi have a mildly acidic pH just like vacuoles of other fungal species including yeast and ectomycorrhizal fungi.

  4. mTORC1 maintains renal tubular homeostasis and is essential in response to ischemic stress

    PubMed Central

    Grahammer, Florian; Haenisch, Nora; Steinhardt, Frederic; Sandner, Lukas; Roerden, Malte; Arnold, Frederic; Cordts, Tomke; Wanner, Nicola; Reichardt, Wilfried; Kerjaschki, Dontscho; Ruegg, Markus A.; Hall, Michael N.; Moulin, Pierre; Busch, Hauke; Boerries, Melanie; Walz, Gerd; Artunc, Ferruh; Huber, Tobias B.

    2014-01-01

    Mammalian target of rapamycin complex 1 (mTORC1) is a key regulator of cell metabolism and autophagy. Despite widespread clinical use of mTORC1 inhibitors, the role of mTORC1 in renal tubular function and kidney homeostasis remains elusive. By using constitutive and inducible deletion of conditional Raptor alleles in renal tubular epithelial cells, we discovered that mTORC1 deficiency caused a marked concentrating defect, loss of tubular cells, and slowly progressive renal fibrosis. Transcriptional profiling revealed that mTORC1 maintains renal tubular homeostasis by controlling mitochondrial metabolism and biogenesis as well as transcellular transport processes involved in countercurrent multiplication and urine concentration. Although mTORC2 partially compensated for the loss of mTORC1, exposure to ischemia and reperfusion injury exaggerated the tubular damage in mTORC1-deficient mice and caused pronounced apoptosis, diminished proliferation rates, and delayed recovery. These findings identify mTORC1 as an important regulator of tubular energy metabolism and as a crucial component of ischemic stress responses. PMID:24958889

  5. Some aspects of proximal tubular sodium chloride reabsorption in Necturus kidney.

    PubMed

    Whittembury, G; Diezi, F; Diezi, J; Spring, K; Giebisch, G

    1975-05-01

    Some aspects of proximal tubular sodium chloride reabsorption in Necturus kidney. Renal tubular reabsorption of fluid and sodium was measured by clearance methods in the doubly perfused Necturus kidney in which the bicarbonate concentration was varied between 0 and 60 mEq/liter. The effects of Damox (2.2 times 10-3M), ocubain (10-5M) and ethacrynic acid (10-4M) and of acidosis were also investigated. In addition to clearance experiments, stationary microperfusion experiments were carried out on promimal tubules to measure volume flow and steady-state sodium and chloride concentration differences across the tubular epithelium. In some experiments, the transepithelial electrical potential difference was also measured using an axial electrode system. The following results were obtained: 1) Bicarbonate is not essential to the operation of renal tubular fluid and sodium transport. 2) Total renal and proximal tubular fluid and sodium transport are partially inhibited by Diamox, ouabian and ethacrynic acid. 3) The proximal tubule maintains a significant transepithelial sodium and chloride concentration difference and a significant electrical potential difference (lumen-negative) in the presence of a poorly permeant nonelectrolyte. The direction and magnitude of the electrical polarization fully accounts for the observed chloride concentration difference. The data support the thesis that sodium chloride transport accross the proximal tubular epithelium takes place by active sodium transport and electically coupled passive chloride reabsorption. Important species differences with respect to mammalian transport mechanisms are discussed.

  6. A Design of Experiments (DOE) approach to optimise temperature measurement accuracy in Solid Oxide Fuel Cell (SOFC)

    NASA Astrophysics Data System (ADS)

    Barari, F.; Morgan, R.; Barnard, P.

    2014-11-01

    In SOFC, accurately measuring the hot-gas temperature is challenging due to low gas velocity, high wall temperature, complex flow geometries and relatively small pipe diameter. Improper use of low cost thermometry system such as standard Type K thermocouples (TC) may introduce large measurement error. The error could have a negative effect on the thermal management of the SOFC systems and consequential reduction in efficiency. In order to study the factors affecting the accuracy of the temperature measurement system, a mathematical model of a TC inside a pipe was defined and numerically solved. The model calculated the difference between the actual and the measured gas temperature inside the pipe. A statistical Design of Experiment (DOE) approach was applied to the modelling data to compute the interaction effect between variables and investigate the significance of each variable on the measurement errors. In this study a full factorial DOE design with six variables (wall temperature, gas temperature, TC length, TC diameter and TC emissivity) at two levels was carried out. Four different scenarios, two sets of TC length (6 - 10.5 mm and 17 - 22 mm) and two different sets of temperature range (550 - 650 °C and 750 - 850 °C), were proposed. DOE analysis was done for each scenario and results were compared to identify key parameters affecting the accuracy of a particular temperature reading.

  7. Analysis of Percent On-Cell Reformation of Methane in SOFC Stacks: Thermal, Electrical and Stress Analysis

    SciTech Connect

    Recknagle, Kurtis P.; Yokuda, Satoru T.; Jarboe, Daniel T.; Khaleel, Mohammad A.

    2006-04-07

    This report summarizes a parametric analysis performed to determine the effect of varying the percent on-cell reformation (OCR) of methane on the thermal and electrical performance for a generic, planar solid oxide fuel cell (SOFC) stack design. OCR of methane can be beneficial to an SOFC stack because the reaction (steam-methane reformation) is endothermic and can remove excess heat generated by the electrochemical reactions directly from the cell. The heat removed is proportional to the amount of methane reformed on the cell. Methane can be partially pre-reformed externally, then supplied to the stack, where rapid reaction kinetics on the anode ensures complete conversion. Thus, the thermal load varies with methane concentration entering the stack, as does the coupled scalar distributions, including the temperature and electrical current density. The endotherm due to the reformation reaction can cause a temperature depression on the anode near the fuel inlet, resulting in large thermal gradients. This effect depends on factors that include methane concentration, local temperature, and stack geometry.

  8. Observations on the oxidation of Mn-modified Ni-base Haynes 230 alloy under SOFC exposure conditions

    SciTech Connect

    Yang, Z Gary; Xia, Gordon; Stevenson, Jeffry W.; Singh, Prabhakar

    2005-07-01

    The commercial Ni-base Haynes 230 alloy (Ni-Cr-Mo-W-Mn) was modified with two increased levels of Mn (1 and 2 wt per cent) and evaluated for its oxidation resistance under simulated SOFC interconnect exposure conditions. Oxidation rate, oxide morphology, oxide conductivity and thermal expansion were measured and compared with commercial Haynes 230. It was observed that additions of higher levels of Mn to the bulk alloy facilitated the formation of a bi-layered oxide scale that was comprised of an outer M3O4 (M=Mn, Cr, Ni) spinel-rich layer at the oxide – gas interface over a Cr2O3-rich sub-layer at the metal – oxide interface. The modified alloys showed higher oxidation rates and the formation of thicker oxide scales compared to the base alloy. The formation of a spinel-rich top layer improved the scale conductivity, especially during the early stages of the oxidation, but the higher scale growth rate resulted in an increase in the area-specific electrical resistance over time. Due to their face-centered cubic crystal structure, both commercial and modified alloys demonstrated a coefficient of thermal expansion that was higher than that of typical anode-supported and electrolyte-supported SOFCs.

  9. JV Task 46 - Development and Testing of a Thermally Integrated SOFC-Gasification System for Biomass Power Generation

    SciTech Connect

    Phillip Hutton; Nikhil Patel; Kyle Martin; Devinder Singh

    2008-02-01

    The Energy & Environmental Research Center has designed a biomass power system using a solid oxide fuel cell (SOFC) thermally integrated with a downdraft gasifier. In this system, the high-temperature effluent from the SOFC enables the operation of a substoichiometric air downdraft gasifier at an elevated temperature (1000 C). At this temperature, moisture in the biomass acts as an essential carbon-gasifying medium, reducing the equivalence ratio at which the gasifier can operate with complete carbon conversion. Calculations show gross conversion efficiencies up to 45% (higher heating value) for biomass moisture levels up to 40% (wt basis). Experimental work on a bench-scale gasifier demonstrated increased tar cracking within the gasifier and increased energy density of the resultant syngas. A series of experiments on wood chips demonstrated tar output in the range of 9.9 and 234 mg/m{sup 3}. Both button cells and a 100-watt stack was tested on syngas from the gasifier. Both achieved steady-state operation with a 22% and 15% drop in performance, respectively, relative to pure hydrogen. In addition, tar tolerance testing on button cells demonstrated an upper limit of tar tolerance of approximately 1%, well above the tar output of the gasifier. The predicted system efficiency was revised down to 33% gross and 27% net system efficiency because of the results of the gasifier and fuel cell experiments. These results demonstrate the feasibility and benefits of thermally integrating a gasifier and a high-temperature fuel cell in small distributed power systems.

  10. Surface Exchange and Bulk Diffusivity of LSCF as SOFC Cathode: Electrical Conductivity Relaxation and Isotope Exchange Characterizations

    SciTech Connect

    Li, Yihong; Gerdes, Kirk; Horita, Teruhisa; Liu, Xingbo

    2013-05-05

    The oxygen diffusion coefficient (D) and surface exchange coefficient (k) of a typical SOFC cathode material, La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3-δ} (LSCF) were characterized by both electrical conductivity relaxation (ECR) and oxygen isotope exchange (IE) methods. Conductivity relaxation experiments were conducted at 800°C for small step changes in partial pressure of oxygen (P{sub O{sub 2}} ), both decreasing and increasing, from 0.02 atm to 0.20 atm. The results revealed P{sub O{sub 2}} dependent hysteresis with the reduction process requiring more equilibration time than oxidation. Analysis of the experimental data indicated that the surface exchange coefficient is a function of the final oxygen partial pressure in an isothermal system. In addition, both forward and backward oxygen reduction reaction constants, which are vital for the fundamental understanding of SOFC cathode reaction mechanisms, are investigated based on the relationship between surface exchange coefficient and P{sub O{sub 2}} . The direct comparisons between the results from both ECR and IE were presented and the possible experimental errors in both methods were discussed.

  11. Electrodeposition of yttria/cobalt oxide and yttria/gold coatings onto ferritic stainless steel for SOFC interconnects

    NASA Astrophysics Data System (ADS)

    Tondo, Elisabetta; Boniardi, Marco; Cannoletta, Donato; De Riccardis, Maria Federica; Bozzini, Benedetto

    Durability seems to be the single most critical issue for the widespread application of SOFCs. Among critical issues, the stability of interconnects - operating at high temperatures in aggressive gas environments - calls for the selection of cheap materials exhibiting high corrosion performance, accompanied by low surface contact resistance. Use of coated AISI 430 stainless steel is currently the state-of-the-art choice. In this paper we propose Y 2O 3, Y 2O 3/Co 3O 4 and Y 2O 3/Au composite films as innovative coatings for AISI 430 plates. These coatings were electrodeposited from chloride salts dissolved in hydroalcoholic solutions containing chitosan as binder. The evolution of the crystalline structure of the electrodeposits with heat-treatment conditions has been studied by XRD, their chemical composition has been evaluated by EDX analysis, their morphology has been observed by SEM and the adhesion has been measured by scratch testing. Coated samples were oxidised in air at 800 °C for times up to 500 h and the area-specific resistance (ASR) as a function of exposure time has been measured. All the coated samples developed ASR values below 100 mΩ cm 2, the target value for SOFC applications. The ASR was found to increase in the order: Y 2O 3/Au, Y 2O 3, and Y 2O 3/Co 3O 4.

  12. 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

  13. Verapamil limits shockwave-induced renal tubular damage in vivo.

    PubMed

    Strohmaier, W L; Abelius, A; Billes, I; Grossmann, T; Wilbert, D M; Bichler, K H

    1994-08-01

    Previous investigations on Madin Darby Canine Kidney (MDCK) cells demonstrated the protective effect of verapamil against shockwave-induced tubular dysfunction. In the present study, we investigated whether verapamil is also protective against shockwave-induced damage in vivo. Male rates were randomly assigned to three groups: verapamil (N = 18) (Group I), control (N = 18) (Group II), or sham treatment (N = 4) (Group III). Groups I and II were treated with 500 shockwaves to each kidney with the Dornier MFL 5000 at 18 kV. Animals assigned to Group III received only anesthesics. Verapamil was given to the animals in Group I for 5 days starting 1 day before shockwave exposure. Urine was collected for 8 hours the day before and immediately, 1.7, and 28 days after shockwave exposure (SWE) for measurement of volume, osmolality, hemoglobin, protein, N-acetyl-beta-glucosaminidase (NAG), beta 2-microglobulin (beta 2M), sodium, and creatinine. Kidneys were perfused and removed for histologic study 1, 7, and 28 days after SWE in six animals of Groups I and II. Blood was taken in these rats (Day 1 after SWE) for the determination of creatinine and sodium and the calculation of the creatinine clearance (CCr) and the fractional excretion of sodium (FENa). After SWE, there was strong diuresis and significantly increased excretion of NAG and beta 2M in the controls, while urine osmolality decreased. These changes were significantly less pronounced in the verapamil-treated rats. The CCr was higher and FENa lower than in the latter group.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Perfluorooctanesulfonate Mediates Renal Tubular Cell Apoptosis through PPARgamma Inactivation.

    PubMed

    Wen, Li-Li; Lin, Chien-Yu; Chou, Hsiu-Chu; Chang, Chih-Cheng; Lo, Hau-Yin; Juan, Shu-Hui

    2016-01-01

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

  15. 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.

  16. 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

  17. 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.

  18. 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.

  19. Proteinuria Increases Plasma Phosphate by Altering Its Tubular Handling

    PubMed Central

    Courbebaisse, Marie; Rutkowski, Joseph M.; Wilhelm-Bals, Alexandra; Metzger, Marie; Khodo, Stellor Nlandu; Hasler, Udo; Chehade, Hassib; Dizin, Eva; Daryadel, Arezoo; Stengel, Bénedicte; Girardin, E.; Prié, Dominique; Wagner, Carsten A.; Scherer, Philipp E.; Martin, Pierre-Yves; Houillier, Pascal; Feraille, Eric

    2015-01-01

    Proteinuria and hyperphosphatemia are cardiovascular risk factors independent of GFR. We hypothesized that proteinuria induces relative phosphate retention via increased proximal tubule phosphate reabsorption. To test the clinical relevance of this hypothesis, we studied phosphate handling in nephrotic children and patients with CKD. Plasma fibroblast growth factor 23 (FGF-23) concentration, plasma phosphate concentration, and tubular reabsorption of phosphate increased during the proteinuric phase compared with the remission phase in nephrotic children. Cross-sectional analysis of a cohort of 1738 patients with CKD showed that albuminuria≥300 mg/24 hours is predictive of higher phosphate levels, independent of GFR and other confounding factors. Albuminuric patients also displayed higher plasma FGF-23 and parathyroid hormone levels. To understand the molecular mechanisms underlying these observations, we induced glomerular proteinuria in two animal models. Rats with puromycin-aminonucleoside–induced nephrotic proteinuria displayed higher renal protein expression of the sodium-phosphate co-transporter NaPi-IIa, lower renal Klotho protein expression, and decreased phosphorylation of FGF receptor substrate 2α, a major FGF-23 receptor substrate. These findings were confirmed in transgenic mice that develop nephrotic-range proteinuria resulting from podocyte depletion. In vitro, albumin did not directly alter phosphate uptake in cultured proximal tubule OK cells. In conclusion, we show that proteinuria increases plasma phosphate concentration independent of GFR. This effect relies on increased proximal tubule NaPi-IIa expression secondary to decreased FGF-23 biologic activity. Proteinuria induces elevation of both plasma phosphate and FGF-23 concentrations, potentially contributing to cardiovascular disease. PMID:25349200

  20. 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

  1. SrMo0.9Co0.1O3-δ: A potential anode for intermediate-temperature solid-oxide fuel cells (IT-SOFC)

    NASA Astrophysics Data System (ADS)

    Martínez-Coronado, R.; Alonso, J. A.; Fernández-Díaz, M. T.

    2014-07-01

    SrMo0.9Co0.1O3-δ oxide has been prepared, characterized and tested as anode material in single solid-oxide fuel cells (SOFC), yielding output powers close to 800 mW cm-2 at 850 °C with pure H2 as a fuel. This excellent performance is accounted for the results of an "in-situ" neutron powder diffraction (NPD) experiment, at the working conditions of a SOFC, showing the presence of a sufficiently high oxygen deficiency, with large displacement factors for oxygen atoms that suggest a large lability and mobility, combined with a huge metal-like electronic conductivity, as high as 386 S cm-1 at T = 50 °C. Besides, the oxidation of the perovskite gives rise to a new oxygen deficient scheelite-like phase with formula SrMo0.9Co0.1O4-δ with Mo(VI), which has been studied by NPD and thermal analysis as far as crystal structure and composition are concerned. An adequate thermal expansion coefficient for both (oxidized and reduced) phases, an excellent reversibility upon cycling in oxidizing-reducing atmospheres and a good chemical compatibility with the electrolyte (La0.8Sr0.2Ga0.83Mg0.17O3-δ; LSGM) make this oxide a good candidate for anode in intermediate-temperature SOFC (IT-SOFCs).

  2. 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

  3. 78 FR 9033 - Certain Oil Country Tubular Goods From the People's Republic of China: Amended Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-07

    ...: Final Results of Antidumping Duty Administrative Review; 2010-2011, 77 FR 74644 (December 17, 2012... petitioner) and American Tubular Products, LLC (``ATP'') (an importer of subject merchandise),...

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

    PubMed

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

    2014-09-01

    Renal involvement in Sjogren's syndrome (SS) is not uncommon and may precede other complaints. Tubulointerstitial nephritis is the most common renal disease in SS and may lead to renal tubular acidosis (RTA), which in turn may cause osteomalacia. Nevertheless, osteomalacia rarely occurs as the first manifestation of a renal tubule disorder due to SS. We herewith describe a 43-year-old woman who was admitted to our hospital for weakness, lumbago and inability to walk. X-ray of the long bones showed extensive demineralization of the bones. Laboratory investigations revealed chronic kidney disease with serum creatinine of 2.3 mg/dL and creatinine clearance of 40 mL/min, hypokalemia (3.2 mmol/L), hypophosphatemia (0.4 mmol/L), hypocalcemia (2.14 mmol/L) and hyperchloremic metabolic acidosis (chlorine: 114 mmol/L; alkaline reserve: 14 mmol/L). The serum alkaline phosphatase levels were elevated. The serum levels of 25-hydroxyvitamin D and 1,25-dihydroxy vitamin D were low and borderline low, respectively, and the parathyroid hormone level was 70 pg/L. Urinalysis showed inappropriate alkaline urine (urinary PH: 7), glycosuria with normal blood glucose, phosphaturia and uricosuria. These values indicated the presence of both distal and proximal RTA. Our patient reported dryness of the mouth and eyes and Schirmer's test showed xerophthalmia. An accessory salivary gland biopsy showed changes corresponding to stage IV of Chisholm and Masson score. Kidney biopsy showed diffuse and severe tubulo-interstitial nephritis with dense lymphoplasmocyte infiltrates. Sicca syndrome and renal interstitial infiltrates indicated SS as the underlying cause of the RTA and osteomalacia. The patient received alkalinization, vitamin D (Sterogyl ®), calcium supplements and steroids in an initial dose of 1 mg/kg/day, tapered to 10 mg daily. The prognosis was favorable and the serum creatinine level was 1.7 mg/dL, calcium was 2.2 mmol/L and serum phosphate was 0.9 mmol/L. PMID:25193912

  5. Human anion exchanger1 mutations and distal renal tubular acidosis.

    PubMed

    Yenchitsomanus, Pa-thai

    2003-09-01

    The human anion exchanger 1 (AE1 or SLC4A1) gene encodes anion exchanger 1 (or band 3) protein in erythrocytes and in alpha-intercalated cells of the kidney. Thus, AE1 mutations show pleiotrophic effects resulting in two distinct and seemingly unrelated defects, an erythrocyte abnormality and distal renal tubular acidosis (dRTA). Southeast Asian ovalocytosis (SAO), a well-known red blood cell (RBC) defect, which is widespread in Southeast Asian regions, is caused by AE1 mutation due to a deletion of 27 base pairs in codons 400-408 (delta400-408) leading to an in-frame 9 amino-acid loss in the protein. Co-existence of SAO and dRTA is usually not seen in the same individual. However, the two conditions can co-exist as the result of compound heterozygosities between delta400-408 and other mutations. The reported genotypes include delta400-408/G701D, delta400-408/R602H, delta400-408/deltaV850, and delta400-408/A858D. The presence of dRTA, with or without RBC abnormalities, may occur from homozygous or compound heterozygous conditions of recessive AE1 mutations (eg G701D/G701D, V488M/V488M, deltaV850/deltaV850, deltaV850/A858D, G701D/S773P) or heterozygous dominant AE1 mutations (eg R598H, R589C, R589S, S613F, R901X). Codon 589 of this gene seems to be a 'mutational hot-spot' since repeated mutations at this codon occurring in different ethnic groups and at least two de novo (R589H and R589C) mutations have been observed. Therefore, AE1 mutations can result in both recessive and dominant dRTA, possibly depending on the position of the amino acid change in the protein. As several mutant AE1 proteins still maintain a significant anion transport function but are defective in targeting to the cell surface, impaired intracellular trafficking of the mutant AE1 is an important molecular mechanism involved in the pathogenesis of dRTA associated with AE1 mutations. PMID:15115146

  6. 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.

  7. Characterization and permeation properties of ZSM-5 tubular membranes

    SciTech Connect

    Coronas, J.; Falconer, J.L.; Noble, R.D.

    1997-07-01

    ZSM-5 zeolite membranes with reproducible properties were prepared by in-situ synthesis on porous {alpha}- and {gamma}-alumina tubular supports and characterized by XRD, SEM and electron microprobe analysis. Single-gas permeances for H{sub 2}, CH{sub 4}, N{sub 2}, CO{sup 2}, n-butane, and i-butane increase over some temperature range, but some gases exhibit maxima or minima. The highest ideal selectivities at room temperature are 299 for N{sub 2}/SF{sub 6}, 392 for H{sup 2}/n-butane, and 2,820 for H{sub 2}/i-butane. These membranes can separate n-butane/i-butane, H{sub 2}/n-butane and H{sub 2}/i-butane mixtures. All n-butane/i-butane separation selectivities have maxima as a function of temperature and are higher than ideal selectivities because n-butane inhibits i-butane permeation. Thus, separation is not by size selectivity, but is due to pore blocking. Temperature dependencies of single-gas permeances and separation selectivities depend strongly on the location of zeolite crystals and the location is determined by preparation procedure. Ideal selectivities also depend strongly on the preparation procedure. When the zeolite forms a continuous layer on the inside surface of the support tubes, pure i-butane permeates faster than pure n-butane so that the single-gas permeances are not determined just by molecular size. The i-butane permeance also increases much more with temperature than the n-butane permeance. The permeation behavior may be the result of permeation through nonzeolitic pores in parallel with zeolite pores. When zeolite crystals are dispersed throughout the pores of {alpha}-alumina supports, permeances are lower and gas permeation and separation properties are quite different. Ideal selectivities are lower, pure n-butane permeates faster than i-butane, and the permeances increase much less with temperature. Separation selectivities are lower but can be maintained to higher temperatures.

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

    PubMed Central

    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

    2016-01-01

    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. PMID:27699213

  9. 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

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

    PubMed

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

    2012-10-01

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

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

    PubMed

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

    2016-01-01

    Tissue engineering of tubular organs such as the blood vessel, trachea gastrointestinal tract, urinary tract are of the great interest due to the high amount of surgeries performed annually on those organs. Development in tissue engineering in recent years and promising results, showed need to investigate more complex constructs that need to be designed in special manner. Stent technology remain the most widely used procedure to restore functions of tubular tissues after cancer treatment, or after organ removal due to traumatic accidents. Tubular structures like blood vessels, intestines, and trachea have to work in specific environment at the boundary of the liquids, solids or air and surrounding tissues and ensure suitable separation between them. This brings additional challenges in tissue engineering science in order to construct complete organs by using combinations of various cells along with the support material systems. Here we give a comprehensive review of the tubular structures of the human body, in perspective of the current methods of treatment and progress in regenerative medicine that aims to develop fully functioning organs of tubular shape. Extensive analysis of the available literature has been done focusing on materials and methods of creations of such organs. This work describes the attempts to incorporate growth factors and drugs within the scaffolds to ensure localized drug release and enhance vascularization of the organ by attracting blood vessels to the site of implantation. PMID:27398431

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

    PubMed

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

    2015-08-01

    The separation and determination of proteins in food is an important aspect in food industry. Inspired by the self-polymerization of dopamine under alkaline conditions and the natural adhesive properties of polydopamine, in this paper, a simple and economical method was developed for the preparation of polydopamine-coated open tubular column, in which ammonium persulfate was used as the source of oxygen to induce and facilitate the polymerization of dopamine to form polydopamine. In comparison with a naked fused-silica capillary, the direction and magnitude of the electro-osmotic flow of the as-prepared polydopamine-coated open tubular column could be manipulated by varying the pH values of background solutions due to the existence of amine and phenolic hydroxyl groups on polydopamine coating. The surface morphology of the polydopamine-coated open tubular column was studied by scanning electron microscopy, and the thickness of polydopamine coating was 106 nm. The performance of the polydopamine-coated open tubular column was validated by analysis of proteins. The relative standard deviations of migration times of proteins representing run-to-run, day-to-day, and column-to-column were less than 3.5%. In addition, the feasibility of the polydopamine-coated open tubular column for real samples was verified by the separation of proteins in chicken egg white and pure milk. PMID:26017540

  13. 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.

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

    PubMed Central

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

    2013-01-01

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

  15. Early urinary biomarkers for renal tubular damage in spontaneously hypertensive rats on a high salt intake.

    PubMed

    Hosohata, Keiko; Yoshioka, Daisuke; Tanaka, Akira; Ando, Hitoshi; Fujimura, Akio

    2016-01-01

    A high salt intake exacerbates hypertension and accelerates renal tubular damage in hypertensive patients. However, data concerning early biomarkers for renal tubular change induced by a high salt intake are limited. The objective of this study was to clarify the time course of new biomarkers for renal tubular damage during high salt intake in spontaneously hypertensive rats (SHR). Male SHR received a regular or high-salt diet from 9 to 17 weeks of age. At 10 weeks of age, a high salt intake caused renal tubular damage, which was further exacerbated at 17 weeks of age. Although albuminuria was detected in salt-loaded SHR at 14 weeks of age, urinary excretion of vanin-1 and neutrophil gelatinase-associated lipocalin (NGAL) was elevated in these animals from 10-17 weeks of age. However, kidney injury molecule-1 (Kim-1) was elevated at 15 weeks of age in salt-loaded SHR. These results suggest that urinary vanin-1 and NGAL are potentially early biomarkers for renal tubular damage in SHR under a high salt intake.

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

    PubMed Central

    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

    2016-01-01

    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.

  17. Muscle imaging in patients with tubular aggregate myopathy caused by mutations in STIM1

    PubMed Central

    Tasca, Giorgio; D'Amico, Adele; Monforte, Mauro; Nadaj-Pakleza, Aleksandra; Vialle, Marc; Fattori, Fabiana; Vissing, John; Ricci, Enzo; Bertini, Enrico

    2015-01-01

    Tubular aggregate myopathy is a genetically heterogeneous disease characterized by tubular aggregates as the hallmark on muscle biopsy. Mutations in STIM1 have recently been identified as one genetic cause in a number of tubular aggregate myopathy cases. To characterize the pattern of muscle involvement in this disease, upper and lower girdles and lower limbs were imaged in five patients with mutations in STIM1, and the scans were compared with two patients with tubular aggregate myopathy not caused by mutations in STIM1. A common pattern of involvement was found in STIM1-mutated patients, although with variable extent and severity of lesions. In the upper girdle, the subscapularis muscle was invariably affected. In the lower limbs, all the patients showed a consistent involvement of the flexor hallucis longus, which is very rarely affected in other muscle diseases, and a diffuse involvement of thigh and posterior leg with sparing of gracilis, tibialis anterior and, to a lesser extent, short head of biceps femoris. Mutations in STIM1 are associated with a homogeneous involvement on imaging despite variable clinical features. Muscle imaging can be useful in identifying STIM1-mutated patients especially among other forms of tubular aggregate myopathy. PMID:26255678

  18. Muscle imaging in patients with tubular aggregate myopathy caused by mutations in STIM1.

    PubMed

    Tasca, Giorgio; D'Amico, Adele; Monforte, Mauro; Nadaj-Pakleza, Aleksandra; Vialle, Marc; Fattori, Fabiana; Vissing, John; Ricci, Enzo; Bertini, Enrico

    2015-11-01

    Tubular aggregate myopathy is a genetically heterogeneous disease characterized by tubular aggregates as the hallmark on muscle biopsy. Mutations in STIM1 have recently been identified as one genetic cause in a number of tubular aggregate myopathy cases. To characterize the pattern of muscle involvement in this disease, upper and lower girdles and lower limbs were imaged in five patients with mutations in STIM1, and the scans were compared with two patients with tubular aggregate myopathy not caused by mutations in STIM1. A common pattern of involvement was found in STIM1-mutated patients, although with variable extent and severity of lesions. In the upper girdle, the subscapularis muscle was invariably affected. In the lower limbs, all the patients showed a consistent involvement of the flexor hallucis longus, which is very rarely affected in other muscle diseases, and a diffuse involvement of thigh and posterior leg with sparing of gracilis, tibialis anterior and, to a lesser extent, short head of biceps femoris. Mutations in STIM1 are associated with a homogeneous involvement on imaging despite variable clinical features. Muscle imaging can be useful in identifying STIM1-mutated patients especially among other forms of tubular aggregate myopathy. PMID:26255678

  19. Losartan attenuates renal interstitial fibrosis and tubular cell apoptosis in a rat model of obstructive nephropathy.

    PubMed

    He, Ping; Li, Detian; Zhang, Beiru

    2014-08-01

    Ureteral obstruction leads to renal injury and progresses to irreversible renal fibrosis, with tubular cell atrophy and apoptosis. There is conflicting evidence concerning whether losartan (an angiotensin II type I receptor antagonist) mitigates renal interstitial fibrosis and renal tubular epithelial cell apoptosis following unilateral ureteral obstruction (UUO) in animal models. The aim of this study was to investigate the effect and mechanism of losartan on renal tubular cell apoptosis and renal fibrosis in a rat model of UUO. The rats were subjected to UUO by ureteral ligation and were treated with dimethyl sulfoxide (control) or losartan. The controls underwent sham surgery. The renal tissues were collected 3, 5, 7 and 14 days after surgery for measurement of various indicators of renal fibrosis. UUO increased the expression levels of α‑smooth muscle actin and collagen I, and the extent of renal tubular fibrosis and apoptosis in a time‑dependent manner. Losartan treatment partially attenuated these responses. Progression of renal interstitial fibrosis was accompanied by phosphorylation of signal transducer and activator of transcription 3 (STAT3) and altered the expression levels of two apoptosis‑related proteins (Bax and Bcl2). Losartan treatment also partially attenuated these responses. The results indicated that losartan attenuated renal fibrosis and renal tubular cell apoptosis in a rat model of UUO. This effect appeared to be mediated by partial blockage of STAT3 phosphorylation.

  20. Epithelial-mesenchymal transition (EMT) of renal tubular cells in canine glomerulonephritis.

    PubMed

    Aresu, Luca; Rastaldi, Maria Pia; Scanziani, Eugenio; Baily, James; Radaelli, Enrico; Pregel, Paola; Valenza, Federico

    2007-11-01

    Tubulo-interstitial fibrosis in dogs may result from primary injury to the interstitium or develop secondary to other renal diseases. As in human renal pathology, tubular epithelial cells (TEC) are believed to actively participate in the mechanisms of renal fibrosis. In this study, we examined the changes in the tubular epithelial component in two specific canine diseases. Immunohistochemistry showed the expression of the epithelial marker cytokeratin, the smooth muscle marker alpha-SMA, the mesenchymal marker vimentin and PCNA in 20 dogs with membranous glomerulonephritis and membrano-proliferative glomerulonephritis. Results showed that the loss of the epithelial marker in TEC was directly correlated to the grade of tubulo-interstitial disease present and independent of the type of glomerulonephritis. Varying degrees of vimentin positivity were detected in tubular epithelium in areas of inflammation, and low numbers of scattered alpha-SMA-positive cells were also observed. Immunohistochemistry showed that epithelial tubular cells lose their cytokeratin staining characteristics and transdifferentiate into cells exhibiting key mesenchymal immunophenotypic feature of vimentin-positive staining in both diseases investigated. The integrity of the tubular basement membrane is likely to be fundamental in maintaining the epithelial phenotype of TEC. Animal models provide opportunities for investigating the pathogenesis of renal fibrosis in humans.

  1. 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.

  2. CD47 regulates renal tubular epithelial cell self-renewal and proliferation following renal ischemia reperfusion.

    PubMed

    Rogers, Natasha M; Zhang, Zheng J; Wang, Jiao-Jing; Thomson, Angus W; Isenberg, Jeffrey S

    2016-08-01

    Defects in renal tubular epithelial cell repair contribute to renal ischemia reperfusion injury, cause acute kidney damage, and promote chronic renal disease. The matricellular protein thrombospondin-1 and its receptor CD47 are involved in experimental renal ischemia reperfusion injury, although the role of this interaction in renal recovery is unknown. We found upregulation of self-renewal genes (transcription factors Oct4, Sox2, Klf4 and cMyc) in the kidney of CD47(-/-) mice after ischemia reperfusion injury. Wild-type animals had minimal self-renewal gene expression, both before and after injury. Suggestive of cell autonomy, CD47(-/-) renal tubular epithelial cells were found to increase expression of the self-renewal genes. This correlated with enhanced proliferative capacity compared with cells from wild-type mice. Exogenous thrombospondin-1 inhibited self-renewal gene expression in renal tubular epithelial cells from wild-type but not CD47(-/-) mice, and this was associated with decreased proliferation. Treatment of renal tubular epithelial cells with a CD47 blocking antibody or CD47-targeting small interfering RNA increased expression of some self-renewal transcription factors and promoted cell proliferation. In a syngeneic kidney transplant model, treatment with a CD47 blocking antibody increased self-renewal transcription factor expression, decreased tissue damage, and improved renal function compared with that in control mice. Thus, thrombospondin-1 via CD47 inhibits renal tubular epithelial cell recovery after ischemia reperfusion injury through inhibition of proliferation/self-renewal.

  3. Medullary nephrocalcinosis, distal renal tubular acidosis and polycythaemia in a patient with nephrotic syndrome

    PubMed Central

    2012-01-01

    Background Medullary nephrocalcinosis and distal renal tubular acidosis are closely associated and each can lead to the other. These clinical entities are rare in patients with nephrotic syndrome and polycythaemia is an unusual finding in such patients. We describe the presence of medullary nephrocalcinosis, distal renal tubular acidosis and polycythaemia in a patient with nephrotic syndrome due to minimal change disease. Proposed mechanisms of polycythaemia in patients with nephrotic syndrome and distal renal tubular acidosis include, increased erythropoietin production and secretion of interleukin 8 which in turn stimulate erythropoiesis. Case presentation A 22 year old Sri Lankan Sinhala male with nephrotic syndrome due to minimal change disease was investigated for incidentally detected polycythaemia. Investigations revealed the presence of renal tubular acidosis type I and medullary nephrocalcinosis. Despite extensive investigation, a definite cause for polycythaemia was not found in this patient. Treatment with potassium and bicarbonate supplementation with potassium citrate led to correction of acidosis thereby avoiding the progression of nephrocalcinosis and harmful effects of chronic acidosis. Conclusion The constellation of clinical and biochemical findings in this patient is unique but the pathogenesis of erythrocytosis is not clearly explained. The proposed mechanisms for erythrocytosis in other patients with proteinuria include increased erythropoietin secretion due to renal hypoxia and increased secretion of interleukin 8 from the kidney. This case illustrates that there may exist hitherto unknown connections between tubular and glomerular dysfunction in patients with nephrotic syndrome. PMID:22834973

  4. Novel ruthenium pyrochlore materials for cathode application in intermediate temperature solid oxide fuel cells (IT-SOFCs)

    NASA Astrophysics Data System (ADS)

    Abate, Chiara

    The performance of solid oxide fuel cells, which operate in the temperature range of 500- 700°C (IT-SOFCs), strongly depends on the cathode employed because the interfacial polarization increases rapidly with decreasing temperature. Pyrochlore oxides with Ru on the B-site of the crystal lattice have been shown to have excellent electro catalytic behaviour for oxygen reduction reaction and high electrical conductivity. These characteristics make pyrochlore ruthenates good candidates for IT-SOFCs cathodes. In this work, several compositions of Y2-xPrxRu 2O7 (x = 0, 0.2, 0.5, 1, 1.5, 2) pyrochlore powders were prepared by a soft precipitation method. All the synthesized powders were single pyrochlore phase with particles size depending on the material compositions. Praseodymium (Pr) was introduced in the A-site with the intent to improve the material electrical proprieties and consequently the overall cathode performance. In fact, without destabilizing the pyrochlore structure, Pr caused structural changes that allow higher electron mobility. The electrical measurements showed that the electrical conductivity of the material increased with increasing the Pr content. Compositions of Y2-xPrxRu2O7 were tested as a cathode to compare its electro-catalytic effect with either of two electrolytes, gadolinium doped ceria (GDC) or erbium stabilized bismuth oxide (ESB). Both systems, Y2-xPrxRu2O 7/ESB and Y2-xPrxRu2O7/GDC, showed a similar variation of the electrode area specific resistance (ASR) with Pr content. This trend was shown to be due to a change of the cathode microstructure upon increasing Pr content. The 25 mol % Pr cathode material on ESB electrolyte presented the best performance. A change of ASR as a function of oxygen partial pressure suggested that the oxygen diffusion is the limiting step of the electrode kinetics. Hence, the better cathode performance on ESB resulted from a much lower charge transfer resistance compared to the GDC system. A partial solid

  5. FEEDSTOCK-FLEXIBLE REFORMER SYSTEM (FFRS) FOR SOLID OXIDE FUEL CELL (SOFC)- QUALITY SYNGAS

    SciTech Connect

    Jezierski, Kelly; Tadd, Andrew; Schwank, Johannes; Kibler, Roland; McLean, David; Samineni, Mahesh; Smith, Ryan; Parvathikar, Sameer; Mayne, Joe; Westrich, Tom; Mader, Jerry; Faubert, F. Michael

    2010-07-30

    The U.S. Department of Energy National Energy Technology Laboratory funded this research collaboration effort between NextEnergy and the University of Michigan, who successfully designed, built, and tested a reformer system, which produced highquality syngas for use in SOFC and other applications, and a novel reactor system, which allowed for facile illumination of photocatalysts. Carbon and raw biomass gasification, sulfur tolerance of non-Platinum Group Metals (PGM) based (Ni/CeZrO2) reforming catalysts, photocatalysis reactions based on TiO2, and mild pyrolysis of biomass in ionic liquids (ILs) were investigated at low and medium temperatures (primarily 450 to 850 C) in an attempt to retain some structural value of the starting biomass. Despite a wide range of processes and feedstock composition, a literature survey showed that, gasifier products had narrow variation in composition, a restriction used to develop operating schemes for syngas cleanup. Three distinct reaction conditions were investigated: equilibrium, autothermal reforming of hydrocarbons, and the addition of O2 and steam to match the final (C/H/O) composition. Initial results showed rapid and significant deactivation of Ni/CeZrO2 catalysts upon introduction of thiophene, but both stable and unstable performance in the presence of sulfur were obtained. The key linkage appeared to be the hydrodesulfurization activity of the Ni reforming catalysts. For feed stoichiometries where high H2 production was thermodynamically favored, stable, albeit lower, H2 and CO production were obtained; but lower thermodynamic H2 concentrations resulted in continued catalyst deactivation and eventual poisoning. High H2 levels resulted in thiophene converting to H2S and S surface desorption, leading to stable performance; low H2 levels resulted in unconverted S and loss in H2 and CO production, as well as loss in thiophene conversion. Bimetallic catalysts did not outperform Ni-only catalysts, and small Ni particles were

  6. Micro-Drilling of Polymer Tubular Ultramicroelectrode Arrays for Electrochemical Sensors

    PubMed Central

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

    2013-01-01

    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. PMID:23673674

  7. 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.

  8. Energetics and electronic structure of tubular Si vacancies filled with carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Kochi, Taketo; Okada, Susumu

    2016-05-01

    We studied the energetics and electronic structure of tubular Si vacancies incorporating a carbon nanotube (CNT), using first-principles total-energy calculations based on the density functional theory. Our calculations show that the incorporated CNT into a Si nanotunnel acts as an atom-thickness liner providing the electrostatically flat nanoscale space inside them by shielding the dangling bond states of tubular Si vacancies. The incorporation of the CNT into the tubular Si vacancies is exothermic with an energy gain up to 7.4 eV/nm depending on the diameters of the vacancy and encapsulated CNT. The electronic states of the vacancy substantially hybridize with those of the CNT, leading to the complex electronic energy band near the Fermi level.

  9. 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.

  10. 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.

  11. pH-sensitive tubular polymersomes: formation and applications in cellular delivery.

    PubMed

    Robertson, James D; Yealland, Guy; Avila-Olias, Milagros; Chierico, Luca; Bandmann, Oliver; Renshaw, Stephen A; Battaglia, Giuseppe

    2014-05-27

    Optimizing the shape of a nanovector influences its interaction with a cell and determines the internalization kinetics. Block copolymer amphiphiles self-assemble into monodisperse structures in aqueous solutions and have been explored extensively as drug delivery vectors. However, the structure of self-assembled block copolymers has mainly been limited to spherical vesicles or spherical and worm-like micelles. Here we show the controlled formation and purification of tubular polymersomes, long cylindrical vesicles. Tubular polymersomes are purified from other structures, and their formation is manipulated by incorporating the biocompatible membrane components cholesterol and phospholipids. Finally we show that these tubular polymersomes have different cellular internalization kinetics compared with spherical polymersomes and can successfully encapsulate and deliver fluorescent bovine serum albumin protein intracellularly.

  12. Isometric tubular vacuolization in renal transplant recipient: the first case report in Thailand.

    PubMed

    Ruangkanchanasetr, Prajej; Praechinavong, Weerasak; Paueksakon, Paisit; Satirapoj, Bancha; Supasyndh, Ouppatham; Supaporn, Thanom

    2012-05-01

    Cyclosporine can cause acute and chronic nephrotoxicity. Renal biopsy is a reliable tool for the diagnosis of cyclosporine nephrotoxicity. The authors report a 56-year-old Thai female with a history of end-stage renal disease who underwent cadaveric renal transplantation. A transplanted kidney biopsy was performed on day 9 post-transplant to identify the cause of delayed graft function. Light and electron microscopic findings revealed widespread (> 50% involvement) numerous tubules filled with uniformly-sized vacuoles in cytoplasm (isometric vacuolization). Serum cyclosporine trough level was 534 ng/mL. Neither acute rejection nor acute tubular necrosis was seen. Diagnosis of acute cyclosporine nephrotoxicity was made. Isometric vacuolization in more than 50% involvement of the tubules is rare (3%) in biopsy specimens. The tubular isometric vacuolization might not have the strong impact to the long term graft outcome. This is the first case report of isometric tubular vacuolization due to cyclosporine toxicity in renal transplant recipient in Thailand.

  13. Engineering of polarized tubular structures in a microfluidic device to study calcium phosphate stone formation†

    PubMed Central

    Wei, Zengjiang; Amponsah, Prince K.; Al-Shatti, Mariyam

    2012-01-01

    This communication describes the formation of tubular structures with a circular cross-section by growing epithelial cells in a microfluidic (MF) device. Here we show for the first time that it is possible to form a monolayer of polarized cells, embedded within the MF device which can function as an in vivo epithelia. We showed: i) the overexpression of specific protein(s) of interest (i.e., ion channel and transport proteins) is feasible inside tubular structures in MFs; ii) the functional kinetic information of Ca2+ in cells can be measured by microflurometry using cell permeable Ca2+ probe under confocal microscope; and iii) calcium phosphate stones can be produced in real time in MFs with Ca2+ transporting epithelia. These data suggest that tubular structures inside this MF platform can be used as a suitable model to understand the molecular and pharmacological basis of calcium phosphate stone formation in the epithelial or other similar cellular micro environments. PMID:22960772

  14. 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)

  15. Species Diversity Regarding the Presence of Proximal Tubular Progenitor Cells of the Kidney

    PubMed Central

    Hansson, J.; Ericsson, A.E.; Axelson, H.; Johansson, M.E.

    2016-01-01

    The cellular source for tubular regeneration following kidney injury is a matter of dispute, with reports suggesting a stem or progenitor cells as the regeneration source while linage tracing studies in mice seemingly favor the classical theory, where regeneration is performed by randomly surviving cells. We, and others have previously described a scattered cell population localized to the tubules of human kidney, which increases in number following injury. Here we have characterized the species distribution of these proximal tubular progenitor cells (PTPCs) in kidney tissue from chimpanzee, pig, rat and mouse using a set of human PTPC markers. We detected PTPCs in chimpanzee and pig kidneys, but not in mouse tissue. Also, subjecting mice to the unilateral urethral obstruction model, caused clear signs of tubular injury, but failed to induce the PTPC phenotype in renal tubules. PMID:26972712

  16. Engineered woven gauntlets to improve the performance of lead/acid tubular plates

    NASA Astrophysics Data System (ADS)

    Terzaghi, G.

    Several research studies have recently demonstrated that adequate compression of positive active material is one of the key determinants of the life of lead/acid batteries. The superior life displayed by batteries with tubular plates, as opposed to those with flat pasted plates, is related to the ability of the gauntlet to retain the active material around each conductive spine of the tubular plate. Woven multi-tubular gauntlets with engineered fabric structure offer higher resistance to chemical oxidation, better energy utilization due to enhanced elastic compression of the active material, and longer trouble-free battery life. Test results are presented to demonstrate that the choice of the gauntlet affects both the performance and life of the cells.

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

    PubMed

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

    2015-01-01

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

  18. Exercise-induced cramp, myoglobinuria, and tubular aggregates in phosphoglycerate mutase deficiency.

    PubMed

    Oh, Shin J; Park, Kyung-Seok; Ryan, Hewitt F; Danon, Moris J; Lu, Jiesheng; Naini, Ali B; DiMauro, Salvatore

    2006-11-01

    We report two patients in whom phosphoglycerate mutase (PGAM) deficiency was associated with the triad of exercise-induced cramps, recurrent myoglobinuria, and tubular aggregates in the muscle biopsy. Serum creatine kinase (CK) levels were elevated between attacks of myoglobinuria. Forearm ischemic exercise tests produced subnormal increases of venous lactate. Muscle biopsies showed subsarcolemmal tubular aggregates in type 2 fibers. Muscle PGAM activities were markedly decreased (3% of the normal mean) and molecular genetic studies showed that both patients were homozygous for a described missense mutation (W78X). A review of 15 cases with tubular aggregates in the muscle biopsies from our laboratory and 15 cases with PGAM deficiency described in the literature showed that this clinicopathological triad is highly suggestive of PGAM deficiency. PMID:16881065

  19. Evaluation of SmCo and SmCoN magnetron sputtering coatings for SOFC interconnect applications

    NASA Astrophysics Data System (ADS)

    Wu, Junwei; Li, Chengming; Johnson, Christopher; Liu, Xingbo

    Cobalt or cobalt containing coatings are promising for SOFC interconnect applications because of their high conductivity. We have investigated SmCo and SmCoN coatings deposited by magnetron sputtering from a SmCo (5% Sm) target on to Crofer 22 APU substrates. The composition, structure, surface morphology, and electrical conductivity of the coated substrates were characterized by SEM/EDX, XRD and ASR measurements. Addition of Sm enhances the oxidation resistance and the Cr retention capability of the coatings. The use of nitride as a precursor stabilizes Sm during oxidation of the films, thus inhibiting diffusion of Fe, resulting in a more compact coating and lowering ASR. The combined advantages of Sm addition to cobalt and the use of a nitride as a precursor, makes SmCoN coatings a promising new interconnect coating material.

  20. SOFC Ohmic Resistance Reduction by HCl-Induced Removal of Manganese at the Anode/Electrolyte Interface

    SciTech Connect

    Marina, Olga A.; Pederson, Larry R.; Thomsen, Edwin C.; Edwards, Danny J.; Coyle, Christopher A.; Cramer, Carolyn N.

    2010-04-09

    The ohmic resistance of anode-supported solid oxide fuel cells having a manganese-based cathode was lowered when operated in synthetic coal gas containing hydrogen chloride. This effect was not observed for cells with cathodes that did not contain manganese. Substantial amounts of Mn were found throughout the grain boundaries of the 8 mole% yttria-stabilized zirconia (8YSZ) electrolyte. Exposure to HCl partially removed Mn near the anode/electrolyte interface, presumably by volatilization as MnCl2(g). This work suggests that one of the underlying causes of higher than expected electrolyte resistance in anode-supported SOFCs is a lowering of the ionic conductivity of 8YSZ by incorporation of manganese.

  1. High Performance Ceramic Interconnect Material for Solid Oxide Fuel Cells (SOFCs): Ca- and Transition Metal-doped Yttrium Chromite

    SciTech Connect

    Yoon, Kyung J.; Stevenson, Jeffry W.; Marina, Olga A.

    2011-10-15

    The effect of transition metal substitution on thermal and electrical properties of Ca-doped yttrium chromite was investigated in relation to use as a ceramic interconnect in high temperature solid oxide fuel cells (SOFCs). 10 at% Co, 4 at% Ni, and 1 at% Cu substitution on B-site of 20 at% Ca-doped yttrium chromite led to a close match of thermal expansion coefficient (TEC) with that of 8 mol% yttria-stabilized zirconia (YSZ), and a single phase Y0.8Ca0.2Cr0.85Co0.1Ni0.04Cu0.01O3 remained stable between 25 and 1100 degree C over a wide oxygen partial pressure range. Doping with Cu significantly facilitated densification of yttrium chromite. Ni dopant improved both electrical conductivity and dimensional stability in reducing environments, likely through diminishing the oxygen vacancy formation. Substitution with Co substantially enhanced electrical conductivity in oxidizing atmosphere, which was attributed to an increase in charge carrier density and hopping mobility. Electrical conductivity of Y0.8Ca0.2Cr0.85Co0.1Ni0.04Cu0.01O3 at 900 degree C is 57 S/cm in air and 11 S/cm in fuel (pO2=5×10^-17 atm) environments. Chemical compatibility of doped yttrium chromite with other cell components was verified at the processing temperatures. Based on the chemical and dimensional stability, sinterability, and thermal and electrical properties, Y0.8Ca0.2Cr0.85Co0.1Ni0.04Cu0.01O3 is suggested as a promising SOFC ceramic interconnect to potentially overcome technical limitations of conventional acceptor-doped lanthanum chromites.

  2. Metallic interconnects for SOFC: Characterisation of corrosion resistance and conductivity evaluation at operating temperature of differently coated alloys

    NASA Astrophysics Data System (ADS)

    Fontana, S.; Amendola, R.; Chevalier, S.; Piccardo, P.; Caboche, G.; Viviani, M.; Molins, R.; Sennour, M.

    One of challenges in improving the performance and cost-effectiveness of solid oxide fuel cells (SOFCs) is the development of suitable interconnect materials. Recent researches have enabled to decrease the operating temperature of the SOFC from 1000 to 800 °C. Chromia forming alloys are then among the best candidates for interconnects. However, low electronic conductivity and volatility of chromium oxide scale need to be solved to improve interconnect performances. In the field of high temperature oxidation of metals, it is well known that the addition of reactive element into alloys or as thin film coatings, improves their oxidation resistance at high temperature. The elements of beginning of the lanthanide group and yttrium are the most efficient. The goal of this study is to make reactive element oxides (La 2O 3, Nd 2O 3 and Y 2O 3) coatings by metal organic chemical vapour deposition (MOCVD) on Crofer 22 APU, AL 453 and Haynes 230 in order to form perovskite oxides which present a good conductivity at high temperature. The coatings were analysed after 100 h ageing at 800 °C in air under atmospheric pressure by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analyses, X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. Area-specific resistance (ASR) was measured in air for the same times and temperature, using a sandwich technique with Pt paste for electrical contacts between surfaces. The ASR values for the best coating were estimated to be limited to 0.035 Ω cm 2, even after 40,000 h use.

  3. High performance ceramic interconnect material for solid oxide fuel cells (SOFCs): Ca- and transition metal-doped yttrium chromite

    NASA Astrophysics Data System (ADS)

    Yoon, Kyung Joong; Stevenson, Jeffrey W.; Marina, Olga A.

    2011-10-01

    The effect of transition metal substitution on thermal and electrical properties of Ca-doped yttrium chromite was investigated in relation to use as a ceramic interconnect in high temperature solid oxide fuel cells (SOFCs). 10 at.% Co, 4 at.% Ni, and 1 at.% Cu substitution on B-site of 20 at.% Ca-doped yttrium chromite led to a close match of thermal expansion coefficient (TEC) with that of 8 mol% yttria-stabilized zirconia (YSZ), and a single phase Y0.8Ca0.2Cr0.85Co0.1Ni0.04Cu0.01O3 remained stable between 25 and 1100 °C over a wide oxygen partial pressure range. Doping with Cu significantly facilitated densification of yttrium chromite. Ni dopant improved both electrical conductivity and dimensional stability in reducing environments, likely through diminishing the oxygen vacancy formation. Substitution with Co substantially enhanced electrical conductivity in oxidizing atmosphere, which was attributed to an increase in charge carrier density and hopping mobility. Electrical conductivity of Y0.8Ca0.2Cr0.85Co0.1Ni0.04Cu0.01O3 at 900 °C is 57 S cm-1 in air and 11 S cm-1 in fuel (pO2 = 5 × 10-17 atm) environments. Chemical compatibility of doped yttrium chromite with other cell components was verified at the processing temperatures. Based on the chemical and dimensional stability, sinterability, and thermal and electrical properties, Y0.8Ca0.2Cr0.85Co0.1Ni0.04Cu0.01O3 is suggested as a promising SOFC ceramic interconnect to potentially overcome technical limitations of conventional acceptor-doped lanthanum chromites.

  4. Enhanced ionic conductivity of apatite-type lanthanum silicate electrolyte for IT-SOFCs through copper doping

    NASA Astrophysics Data System (ADS)

    Ding, Xifeng; Hua, Guixiang; Ding, Dong; Zhu, Wenliang; Wang, Hongjin

    2016-02-01

    Apatite-type Lanthanum silicate (LSO) is among the most promising electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs) owing to the high conductivity and low activation energy at lower temperature than traditional doped-zirconia electrolyte. The ionic conductivity as well as the sintering density of lanthanum silicate oxy-apatite, La10Si6-xCuxO27-δ (LSCO, 0 ≤ x ≤ 2), was effectively enhanced through a small amount of doped copper. The phase composition, relative density, ionic conductivity and thermal expansion behavior of La10Si6-xCuxO27-δ was systematically investigated by X-ray diffraction (XRD), Archimedes' drainage method, scanning electron microscope (SEM), electrochemical impedance spectra (EIS) and thermal dilatometer techniques. With increasing copper doping content, the ionic conductivity of La10Si6-xCuxO27-δincreased, reaching a maximum of 4.8 × 10-2 S cm-1 at 800 °C for x = 1.5. The improved ionic conductivity could be primarily associated with the enhanced grain conductivity. The power output performance of NiO-LSCO/LSCO/LSCF single cell was superior to that obtained on NiO-LSO/LSO/LSCF at different temperatures using hydrogen as fuel and oxygen as oxidant, which could be attributed to the enhanced oxygen ionic conductivity as well as the sintering density for the copped doped lanthanum silicate. In conclusion, the apatite La10Si4.5Cu1.5O25.5 is a promising candidate electrolyte for IT-SOFCs.

  5. Hydrogen Fueled Hybrid Solid Oxide Fuel Cell-Gas Turbine (SOFC-GT) System for Long-Haul Rail Application

    NASA Astrophysics Data System (ADS)

    Chow, Justin Jeff

    Freight movement of goods is the artery for America's economic health. Long-haul rail is the premier mode of transport on a ton-mile basis. Concerns regarding greenhouse gas and criteria pollutant emissions, however, have motivated the creation of annually increasing locomotive emissions standards. Health issues from diesel particulate matter, especially near rail yards, have also been on the rise. These factors and the potential to raise conventional diesel-electric locomotive performance warrants the investigation of using future fuels in a more efficient system for locomotive application. This research evaluates the dynamic performance of a Solid Oxide Fuel Cell-Gas Turbine (SOFC-GT) Hybrid system operating on hydrogen fuel to power a locomotive over a rail path starting from the Port of Los Angeles and ending in the City of Barstow. Physical constraints, representative locomotive operation logic, and basic design are used from a previous feasibility study and simulations are performed in the MATLAB Simulink environment. In-house controls are adapted to and expanded upon. Results indicate high fuel-to-electricity efficiencies of at least 54% compared to a conventional diesel-electric locomotive efficiency of 35%. Incorporation of properly calibrated feedback and feed-forward controls enables substantial load following of difficult transients that result from train kinematics while maintaining turbomachinery operating requirements and suppressing thermal stresses in the fuel cell stack. The power split between the SOFC and gas turbine is deduced to be a deterministic factor in the balance between capital and operational costs. Using hydrogen results in no emissions if renewable and offers a potential of 24.2% fuel energy savings for the rail industry.

  6. Material Degradation during Isothermal Aging and Thermal Cycling of Hybrid Mica Seal with Ag Interlayer under SOFC Exposure Conditions

    SciTech Connect

    Chou, Y. S.; Stevenson, Jeffry W.; Hardy, John S.; Singh, Prabhakar

    2006-11-01

    Hybrid phlogopite mica seals with silver interlayers were evaluated in terms of materials degradation in a combined isothermal ageing and thermal cycling test. The hybrid mica seal was composed of a phlogopite mica paper sandwiched between two Ag foils. The hybrid micas were first aged at 800oC for ~1,000 hrs in a moist, dilute hydrogen fuel (~2.7% H2/bal. Ar + ~3% H2O), followed by short-term thermal cycling between ~100oC and 800oC. The combined test was repeated for 3 times for a total of 4,000 hrs ageing at 800oC and 119 thermal cycles. The results of high temperature leak rate tests showed very good thermal stability and thermal cycle stability with 800oC leak rates of ~0.02-0.03 sccm/cm. A hybrid mica seal tested in a high water content fuel (30 v% H2O/70 v% H2) demonstrated similar leakage during isothermal ageing and subsequent thermal cycles. Post-mortem analyses showed no extensive reaction between Ag and phlogopite mica as well as no significant mica degradation. Simple calculations to estimate the effect of measured leakage on the open circuit voltage and the total fuel loss for various SOFC stack sizes suggest very small fuel losses for the current hybrid mica seals, indicating that they are good candidates for SOFC sealing applications. Corresponding author: Yeong-Shyung Chou Tel: 509-375-2527, Fax: 509-375-2186, E-mail: yeong-shyung.chou@pnl.gov

  7. 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.

  8. 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.

  9. A tubular dielectric elastomer actuator: Fabrication, characterization and active vibration isolation

    NASA Astrophysics Data System (ADS)

    Sarban, R.; Jones, R. W.; Mace, B. R.; Rustighi, E.

    2011-11-01

    This contribution reviews the fabrication, characterization and active vibration isolation performance of a core-free rolled tubular dielectric elastomer (DE) actuator, which has been designed and developed by Danfoss PolyPower A/S. PolyPower DE material, PolyPower TM, is produced in thin sheets of 80 μm thickness with corrugated metallic electrodes on both sides. Tubular actuators are manufactured by rolling the DE sheets in a cylindrical shape. The electromechanical characteristics of such actuators are modeled based on equilibrium pressure equation. The model is validated with experimental measurements from 3 actuators. The dynamic characteristics of three tubular actuators fabricated from the same batch of manufactured DE material are presented and compared to: (a) provide insight into the ability of the fabrication process to produce actuators with similar characteristics and (b) highlight the dominant dynamic characteristics of the core-free tubular actuator. It has been observed that all actuators have similar dynamic characteristics in a frequency range up to 1 kHz. A tubular actuator is then used to provide active vibration isolation (AVI) of a 250 g mass subject to shaker generated 'ground vibration'. An adaptive feedforward control approach is used to achieve this. The tubular actuator is shown to provide excellent isolation against harmonic vibratory disturbances with attenuation of the resulting 5 and 10 Hz harmonics being 66 and 23 dB, respectively. AVI against a narrow band vibratory disturbance with frequency content 2-8 Hz, produced an attenuation of 20 dB across the frequency band.

  10. Study of the Heat-Transfer Processes of Tubular Elements of Ground Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Kusaiynov, K.; Shuyushbayeva, N. N.; Shaimerdenova, K. M.; Nurgalieva, Zh. G.; Omarov, N. N.

    2015-05-01

    In this paper, consideration is given to the efficiency of utilization of the low-potential heat of the ground. Also, the advantages and distinctive features of polyethylene tubes used in vertical tubular elements of heat pumps are described. This paper gives the results of investigation of the heat transfer of tubular elements of ground heat exchangers. The dependences of the temperature distributions in the ground in the vicinity of a tube and the change in the temperature with time in dry and moist grounds are determined.

  11. A magnetic minirobot with anchoring and drilling ability in tubular environments actuated by external magnetic fields

    NASA Astrophysics Data System (ADS)

    Choi, K.; Jeon, S. M.; Nam, J. K.; Jang, G. H.

    2015-05-01

    We propose a magnetic minirobot with anchoring and drilling ability (MMAD) controlled by an external magnetic field. The proposed MMAD can navigate through a tubular environment, such as human blood vessels, actuated by a magnetic gradient and uniform rotating magnetic field. It can also generate an anchoring motion, which stably holds the position of the MMAD under pulsatile flow, in order to drill and unclog obstructed blood vessels. The operating conditions of the MMAD were examined by investigating the magnetic torques, and the holding force of the MMAD was measured by a force sensing resistor. Finally, we performed various experiments in a tubular environment to verify the validity of the proposed MMAD.

  12. 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.

  13. Mesenchymal Stem Cells Modulate Albumin-Induced Renal Tubular Inflammation and Fibrosis

    PubMed Central

    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. PMID:24646687

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

    PubMed

    Ries, H; Spirkl, W

    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.

  15. Facile Fabrication of Uniform Polyaniline Nanotubes with Tubular Aluminosilicates as Templates

    NASA Astrophysics Data System (ADS)

    Zhang, Long; Liu, Peng

    2008-08-01

    The uniform polyaniline (PANI) nanotubes, with inner diameter, outer diameter, and tubular thickness of 40, 60, and 10 nm, respectively, were prepared successfully by using natural tubular aluminosilicates as templates. The halloysite nanotubes were coated with PANI via the in situ chemical oxidation polymerization. Then the templates were etched with HCl/HF solution. The PANI nanotubes were characterized using FTIR, X-ray diffraction, and transmission electron microscopy. The conductivity of the PANI nanotubes was found to be 1.752 × 10-5 (Ω·cm)-1.

  16. 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.

  17. A mouse model of renal tubular injury of tyrosinemia type 1: development of de Toni Fanconi syndrome and apoptosis of renal tubular cells in Fah/Hpd double mutant mice.

    PubMed

    Sun, M S; Hattori, S; Kubo, S; Awata, H; Matsuda, I; Endo, F

    2000-02-01

    Hereditary tyrosinemia type 1 (HT1) (McKusick 276700), a severe autosomal recessive disorder of tyrosine metabolism, is caused by mutations in the fumarylacetoacetate hydrolase gene Fah (EC 3.7.1.2), which encodes the last enzyme in the tyrosine catabolic pathway. HT1 is characterized by severe progressive liver disease and renal tubular dysfunction. Homozygous disruption of the gene encoding Fah in mice causes neonatal lethality (e.g., lethal Albino deletion c14CoS mice), an event that limits use of this animal as a model for HT1. A new mouse model was developed with two genetic defects, Fah and 4-hydroxyphenylpyruvate dioxygenase (Hpd). The Fah-/- Hpd-/- mice grew normally without evidence of liver and renal disease, and the phenotype is similar to that in Fah+/+ Hpd-/- mice. The renal tubular cells of Fah-/- Hpd-/- mice, particularly proximal tubular cells, underwent rapid apoptosis when homogentisate, the intermediate metabolite between HPD and FAH, was administered to the Fah-/- Hpd-/- mice. Simultaneously, renal tubular function was impaired and Fanconi syndrome occurred. Apoptotic death of renal tubular cells, but not renal dysfunction, was prevented by pretreatment of the animals with YVAD, a specific inhibitor of caspases. In the homogentisate-treated Fah-/- Hpd-/- mice, massive amounts of succinylacetone were excreted into the urine, regardless of treatment with inhibitors. It is suggested that apoptotic death of renal tubular cells, as induced by administration of homogentisate to Fah-/- Hpd-/- mice, was caused by an intrinsic process, and that renal apoptosis and tubular dysfunctions in tubular cells occurred through different pathways. These observations shed light on the pathogenesis of renal tubular injury in subjects with FAH deficiency. These Fah-/- Hpd-/- mice can serve as a model in experiments related to renal tubular damage.

  18. Composite Epstein-Barr Virus-Associated B-Cell Lymphoproliferative Disorder and Tubular Adenoma in a Rectal Polyp.

    PubMed

    Lo, Amy A; Gao, Juehua; Rao, M Sambasivia; Yang, Guang-Yu

    2016-02-01

    Composite tumors are formed when there is intermingling between two components of separate tumors seen histologically. Cases demonstrating composite tubular adenoma with other types of tumors in the colon are rare. Composite tubular adenomas with nonlymphoid tumors including carcinoids, microcarcinoids, and small cell undifferentiated carcinoma have been reported in the literature. The occurrence of composite lymphoma and tubular adenoma within the colorectal tract is extremely rare. Only three cases have been reported and include one case of mantle cell lymphoma and two cases of diffuse large B-cell lymphoma arising in composite tubular adenomas. We present the first case of composite Epstein-Barr virus-associated B-cell lymphoproliferative disorder and tubular adenoma in a rectal polyp with a benign endoscopic appearance.

  19. 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...

  20. 46 CFR 154.1320 - Sighting ports, tubular gauge glasses, and flat plate type gauge glasses.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 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...