Sample records for secondary electrochemical cell

  1. Electrochemical cell

    DOEpatents

    Kaun, Thomas D. (New Lenox, IL)

    1984-01-01

    An improved secondary electrochemical cell is disclosed having a negative electrode of lithium aluminum, a positive electrode of iron sulfide, a molten electrolyte of lithium chloride and potassium chloride, and the combination that the fully charged theoretical capacity of the negative electrode is in the range of 0.5-1.0 that of the positive electrode. The cell thus is negative electrode limiting during discharge cycling. Preferably, the negative electrode contains therein, in the approximate range of 1-10 volume % of the electrode, an additive from the materials of graphitized carbon, aluminum-iron alloy, and/or magnesium oxide.

  2. Corrosion resistant positive electrode for high-temperature, secondary electrochemical cell

    DOEpatents

    Otto, N.C.; Warner, B.T.; Smaga, J.A.; Battles, J.E.

    1982-07-07

    The corrosion rate of low carbon steel within a positive electrode of a high-temperature, secondary electrochemical cell that includes FeS as active material is substantially reduced by incorporating therein finely divided iron powder in stoichiometric excess to the amount required to form FeS in the fully charged electrode. The cell typically includes an alkali metal or alkaline earth metal as negative electrode active material and a molten metal halide salt as electrolyte. The excess iron permits use of inexpensive carbon steel alloys that are substantially free of the costly corrosion resistant elements chromium, nickel and molybdenum while avoiding shorten cell life resulting from high corrosion rates.

  3. Electrode for electrochemical cell

    SciTech Connect

    Kaun, T.D.; Miller, W.E.; Nelson, P.A.

    1981-12-15

    An electrode structure for a secondary electrochemical cell includes an outer enclosure defining a compartment containing electrochemical active material. The enclosure includes a rigid electrically conductive metal sheet with perforated openings over major side surfaces. The enclosure can be assembled as first and second trays each with a rigid sheet of perforated electrically conductive metal at major side surfaces and normally extending flanges at parametric margins. The trays can be pressed together with moldable active material between the two to form an expandable electrode. A plurality of positive and negative electrodes thus formed are arranged in an alternating array with porous frangible interelectrode separators within the housing of the secondary electrochemical cell.

  4. Method of forming components for a high-temperature secondary electrochemical cell

    DOEpatents

    Mrazek, F.C.; Battles, J.E.

    1981-05-22

    A method of forming a component for a high-temperature secondary electrochemical cell having a positive electrode including a sulfide selected from the group consisting of iron sulfides, nickel sulfides, copper sulfides and cobalt sulfides, a negative electrode including an alloy of aluminum and an electrically insulating porous separator between said electrodes is described. The improvement comprises forming a slurry of solid particles dispersed in a liquid electrolyte such as the lithium chloride-potassium chloride eutectic, casting the slurry into a form having the shape of one of the components and smoothing the exposed surface of the slurry, cooling the cast slurry to form the solid component, and removing same. Electrodes and separators can be thus formed.

  5. Electrochemical cell

    DOEpatents

    Redey, L.I.; Vissers, D.R.; Prakash, J.

    1996-07-16

    An electrochemical cell is described having a bimodal positive electrode, a negative electrode of an alkali metal, and a compatible electrolyte including an alkali metal salt molten at the cell operating temperature. The positive electrode has an electrochemically active layer of at least one transition metal chloride at least partially present as a charging product, and additives of bromide and/or iodide and sulfur in the positive electrode or the electrolyte. Electrode volumetric capacity is in excess of 400 Ah/cm{sup 3}; the cell can be 90% recharged in three hours and can operate at temperatures below 160 C. There is also disclosed a method of reducing the operating temperature and improving the overall volumetric capacity of an electrochemical cell and for producing a positive electrode having a BET area greater than 6{times}10{sup 4}cm{sup 2}/g of Ni. 6 figs.

  6. Electrochemical cell

    DOEpatents

    Redey, L.I.; Vissers, D.R.; Prakash, J.

    1994-02-01

    An electrochemical cell is described having a bimodal positive electrode, a negative electrode of an alkali metal, and a compatible electrolyte including an alkali metal salt molten at the cell operating temperature. The positive electrode has an electrochemically active layer of at least one transition metal chloride at least partially present as a charging product, and additives of bromide and/or iodide and sulfur in the positive electrode or the electrolyte. Electrode volumetric capacity is in excess of 400 Ah/cm[sup 3]; the cell can be 90% recharged in three hours and can operate at temperatures below 160 C. There is also disclosed a method of reducing the operating temperature and improving the overall volumetric capacity of an electrochemical cell and for producing a positive electrode having a BET area greater than 6[times]10[sup 4] cm[sup 2]/g of Ni. 8 figures.

  7. Electrochemical cell

    DOEpatents

    Redey, L.I.; Myles, K.M.; Vissers, D.R.; Prakash, J.

    1996-07-02

    An electrochemical cell is described with a positive electrode having an electrochemically active layer of at least one transition metal chloride. A negative electrode of an alkali metal and a compatible electrolyte including an alkali metal salt molten at cell operating temperature is included in the cell. The electrolyte is present at least partially as a corrugated {beta}{double_prime} alumina tube surrounding the negative electrode interior to the positive electrode. The ratio of the volume of liquid electrolyte to the volume of the positive electrode is in the range of from about 0.1 to about 3. A plurality of stacked electrochemical cells is disclosed each having a positive electrode, a negative electrode of an alkali metal molten at cell operating temperature, and a compatible electrolyte. The electrolyte is at least partially present as a corrugated {beta}{double_prime} alumina sheet separating the negative electrode and interior to the positive electrodes. The alkali metal is retained in a porous electrically conductive ceramic, and seals for sealing the junctures of the electrolyte and the adjacent electrodes at the peripheries thereof. 8 figs.

  8. Electrochemical cell

    DOEpatents

    Nagy, Zoltan (Woodridge, IL); Yonco, Robert M. (LaGrange, IL); You, Hoydoo (Naperville, IL); Melendres, Carlos A. (Lemont, IL)

    1992-01-01

    An electrochemical cell has a layer-type or sandwich configuration with a Teflon center section that houses working, reference and counter electrodes and defines a relatively narrow electrolyte cavity. The center section is surrounded on both sides with thin Teflon membranes. The membranes are pressed in place by a pair of Teflon inner frames which are in turn supported by a pair of outer metal frames. The pair of inner and outer frames are provided with corresponding, appropriately shaped slits that are in plane generally transverse to the plane of the working electrode and permit X-ray beams to enter and exit the cell through the Teflon membranes that cover the slits so that the interface between the working electrode and the electrolyte within the cell may be analyzed by transmission geometry. In one embodiment, the center section consists of two parts, one on top of the other. Alternatively, the center section of the electrochemical cell may consist of two intersliding pieces or may be made of a single piece of Teflon sheet material. The electrolyte cavity is shaped so that the electrochemical cell can be rotated 90.degree. in either direction while maintaining the working and counter electrodes submerged in the electrolyte.

  9. Electrochemical cell

    DOEpatents

    Nagy, Z.; Yonco, R.M.; You, H.; Melendres, C.A.

    1992-08-25

    An electrochemical cell has a layer-type or sandwich configuration with a Teflon center section that houses working, reference and counter electrodes and defines a relatively narrow electrolyte cavity. The center section is surrounded on both sides with thin Teflon membranes. The membranes are pressed in place by a pair of Teflon inner frames which are in turn supported by a pair of outer metal frames. The pair of inner and outer frames are provided with corresponding, appropriately shaped slits that are in plane generally transverse to the plane of the working electrode and permit X-ray beams to enter and exit the cell through the Teflon membranes that cover the slits so that the interface between the working electrode and the electrolyte within the cell may be analyzed by transmission geometry. In one embodiment, the center section consists of two parts, one on top of the other. Alternatively, the center section of the electrochemical cell may consist of two intersliding pieces or may be made of a single piece of Teflon sheet material. The electrolyte cavity is shaped so that the electrochemical cell can be rotated 90[degree] in either direction while maintaining the working and counter electrodes submerged in the electrolyte. 5 figs.

  10. Electrochemical cell

    SciTech Connect

    Walsh, F.M.

    1986-12-23

    This patent describes an electrochemical cell having a metal anode wherein the metal is selected from zinc and cadmium; a bromine cathode; and an aqueous electrolyte containing a metal bromide, the metal bromide having the same metal as the metal of the anode. The improvement described here comprises: a bromine complexing agent in the aqueous metal bromide electrolyte, the complexing agent consisting solely of a quaternary ammonium salt of an N-organo substituted alpha amino acid, ester, or betaine.

  11. The electrochemical behaviors of Zn-Al-La-hydrotalcite in Zn-Ni secondary cells

    NASA Astrophysics Data System (ADS)

    Fan, Xinming; Yang, Zhanhong; Xie, Xiaoe; Long, Wei; Wang, Ruijuan; Hou, Zhilin

    2013-11-01

    Zn-Al-La-CO3 layered double hydroxides (LDHs) are prepared by the constant pH co-precipitation method and proposed as a novel anodic material in Zinc-Nickel secondary cells. The X-ray diffraction (XRD) patterns and scanning electron microscopy (SEM) images reveal that the as-prepared samples are well-crystallized and hexagon layer structure. Electrochemical performances of Zn-Al-La-hydrotalcites with different Zn/Al/La molar ratios are investigated by galvanostatic charge-discharge measurements, cyclic voltammograms (CV) and Tafel polarization curves. In comparison with the Zn-Al-hydrotalcite, Zn-Al-La-hydrotalcites with different Zn/Al/La molar ratios have more stable cycling performance. After 400 cell cycles, Zn-Al-La-LDH with Zn/Al/La = 3:0.8:0.2 retains specific discharge capacity of 297 mAh g-1 with a retention rate of 79.0%, which is much superior to that of 205 mAh g-1 with a retention rate of 53.5% for the Zn-Al-La-LDH with Zn/Al/La = 3:0.9:0.1 and 241 mAh g-1 with a retention rate of 69.0% for the Zn-Al-La-LDH with Zn/Al/La = 3:0.6:0.4. The results demonstrate that the Zn-Al-La-LDH with Zn/Al/La = 3:0.8:0.2 has the best reversible cycling behavior. The CV exhibits well reversibility and the Tafel polarization curves reveal more positive corrosion potential for Zn-Al-La-hydrotalcite.

  12. Electrochemical cell

    DOEpatents

    Redey, L.I.; Vissers, D.R.; Prakash, J.

    1994-08-23

    An electrochemical cell is described having an alkali metal negative electrode such as sodium and a positive electrode including Ni or transition metals, separated by a [beta] alumina electrolyte and NaAlCl[sub 4] or other compatible material. Various concentrations of a bromine, iodine and/or sulfur containing additive and pore formers are disclosed, which enhance cell capacity and power. The pore formers may be the ammonium salts of carbonic acid or a weak organic acid or oxamide or methylcellulose. 6 figs.

  13. Electrochemical cell

    SciTech Connect

    Notten, P.H.L.

    1991-12-10

    This patent describes an electrochemical cell comprising a negative electrode. It comprises an electrochemical active material consisting of an intermetallic compound of the formula AB{sub m}C{sub n} wherein m plus n is between 4.8 and 5.4, n has a value of up to 0.6 and greater than 0, A is a Mischmetall or at least one element of the group consisting of Y, Ti, Hf, Zr, Ca, Th, La and the remaining rare earth metals, B is at least two elements selected from the group consisting of Ni, Co, Cu, Fe and Mn and C consists of at least one element selected from the group consisting of Al, Cr, and Si, and has a CaCu{sub 5} structure, and a catalytic material at the surface of which hydrogen exhibits a large electrochemical activity, the catalytic material having a composition of formula DE{sub 3} wherein D is at least one element selected from the group consisting of Cr, Mo and W and E is at least one element selected from the group consisting of Ni and Co.

  14. Electrochemical cell

    SciTech Connect

    Heuts, J.J.F.; Frens, G.

    1987-10-27

    An electrochemical cell is described comprising a negative electrode. The electrochemically active material consists of an intermetallic compound forming a hydride with hydrogen, which compound has the CaCu/sub 5/-structure and the compositional formula AB/sub m/C/sub n/, where m+n is between 4.8 and 5.4, and where n is between 0.05 and 0.6. A consists of Mischmetall or of at least one element selected from the group consisting of Y, Ti, Hf, Zr, Ca, Th, La and the remaining rare earth metals, in which the total atomic quantities of the elements Y, Ti, Hf and Zr may not be more than 40% of A. B consists of two or more elements selected from the group consisting of Ni, Co, Cu, Fe and Mn, the maximum atomic quantity per gram atom of A is being for Ni:3.5, for Co:3.5, for Cu:3.5, for Fe:2.0 and for Mn:1.0. C consists of at least one element selected from the group consisting of Al, Cr and Si in the following atomic quantities: Al:0.05-0.6, Cr:0.05-0.5 and Si:0.05-0.5, characterized in that the electrochemically active material of the negative electrode also comprises an intermetallic compound forming a hydride with hydrogen, of the compositional formula DNihd pE/sub q/ in an amount from 5 to 45% by weight calculated on the total amount of electrochemically active material, where p+q is between 4.8 and 5.4, where p is between 3.5 and 5.4, where q has a value from 0 to 1.5. D is selected from the group formed by La and Mischmetall, and E consists of one or more elements selected from the group consisting of Co, Cr, Mn and Cu.

  15. The electrochemical performances of Zn-Sn-Al-hydrotalcites in Zn-Ni secondary cells

    NASA Astrophysics Data System (ADS)

    Wang, Tingting; Yang, Zhanhong; Yang, Bin; Wang, Ruijuan; Huang, Jianhang

    2014-07-01

    Zn-Sn-Al-hydrotalcites (LDHs) have been successfully prepared by hydrothermal method and applied as a novel anodic active material in Zn-Ni secondary batteries. The scanning electron microscopy (SEM), X-ray diffractometer (XRD) and FT-IR tests are performed to investigate the morphology and microstructure of Zn-Sn-Al-hydrotalcites. Electrochemical performances of Zn-Sn-Al-hydrotalcites with different Zn/Sn/Al molar ratios are investigated through galvanostatic charge-discharge measurements, cyclic voltammograms (CV) and Tafel polarization curves. Compared with Zn-Al-LDH without Sn addition, Zn-Sn-Al-LDHs still present hexagon layer structure, and present more excellent electrochemical performance. And Zn-Sn-Al-LDH with the molar ratio of 2.8:0.2:1 shows a better cycle stability than the other samples. The results demonstrate that Sn addition can help to perfect the electrochemical performance of zinc electrode with Zn-Sn-Al-LDHs. At the same time, CV tests indicate well reversibility and Tafel curves reveal more positive corrosion potential for Zn-Sn-Al-LDHs.

  16. Electrochemical cell

    SciTech Connect

    Heuts, J.J.F.G.; Willems, J.J.G.S.A.

    1987-10-13

    An electrochemical cell is described comprising a negative electrode. The electrochemically active material of which consists of an intermetallic compound forming a hydride with hydrogen, which compound has the CaCu/sub 5/-structure and the compositional formula AB/sub m/C/sub n/, where m+n is between 4.8 and 5.4, where n is between 0.05 and 0.6, in which A consists of Misch-metal or of one or more elements selected from the group consisting of Y, Ti, Hf, Zr, Ca, Th, La and the remaining rare earth metals, in which the total atomic quantities of the elements Y, Ti, Hf and Zr may not be more than 40% of A. B consists of two or more elements selected from the group formed by Ni, Co, Cu, Fe and Mn, where the maximum atomic quantity per gram atom of A is for Ni: 3.5, for Co:3.5, for Cu:3.5, for Fe:2.0 and for Mn:1.0, and C consists of one or more elements selected from the group formed by Al, Cr and Si in the indicated atomic quantities: Al:0.05-0.6, Cr:0.05-0.5 and Si:0.05-0.5, characterized in that the electrochemically active material additionally comprises one or more metals selected from the group formed by Pd, Pt, Ir and Rh, the atomic quantity per gram atom of A being from 0.001 to 0.5.

  17. Electrochemical behavior of Li/LiV3O8 secondary cells

    NASA Astrophysics Data System (ADS)

    Bak, Hyo Rim; Lee, Jae Ha; Kim, Bok Ki; Yoon, Woo Young

    2013-03-01

    Li/LiV3O8 secondary cells with Li-foil and Li-powder anodes were fabricated, and their electrical properties were compared. Using the powder anode, a cell with an initial discharge capacity of 260 mAh g-1 that could be operated for over 100 cycles was obtained. The porous Li-powder electrode was safely synthesized by pressing an emulsion droplet onto an SUS mesh. A threefold increase in the electrical conductivity of the LiV3O8 cathode was achieved by the addition of carbon using a vibration pot mill. Using the powder anode resulted in 80% capacity retention at the 100th cycle, while that using the foil electrode was 46%; the 1.0 Crate/ 0.1 C-rate capacity ratio also increased from 44% to 60%. A cell employing the LiV3O8-carbon composite cathode showed better electrical performance, a capacity retention of 90% after 50 cycles, and an increase in rate capacity ratio. The crystal structure and morphology of the LiV3O8-C composite were investigated by x-ray diffraction and scanning electron microscopy.

  18. Electrochemical cell

    SciTech Connect

    Dageforde, A. F.

    1980-02-05

    The present invention is directed to certain modifications to sensor cells to minimize electrolyte dilution or loss and to reduce electrical noise. These objectives are attained by designing and constructing the cell in such a manner as to force the electrolyte to communicate between the anode and cathode by diffusion through a porous plug which is placed adjacent the cathode and in contact with the required porous membrane.

  19. Electrochemical cell stack assembly

    DOEpatents

    Jacobson, Craig P.; Visco, Steven J.; De Jonghe, Lutgard C.

    2010-06-22

    Multiple stacks of tubular electrochemical cells having a dense electrolyte disposed between an anode and a cathode preferably deposited as thin films arranged in parallel on stamped conductive interconnect sheets or ferrules. The stack allows one or more electrochemical cell to malfunction without disabling the entire stack. Stack efficiency is enhanced through simplified gas manifolding, gas recycling, reduced operating temperature and improved heat distribution.

  20. Portable electrochemical cell interrogator

    SciTech Connect

    Doss, J.D.; McCabe, C.W.

    1984-11-01

    We have designed a portable electronic instrument for interrogating electrochemical cells. The instrument is powered by a 9-V battery and has an LCD digital readout. It can read out any instrument that has electrochemical cells that increase in impedance upon deplating.

  1. Calculating Pressures In Electrochemical Cells

    NASA Technical Reports Server (NTRS)

    Lutwack, Ralph; Frank, Harvey A.; Attia, Alan I.

    1992-01-01

    Initial pressure and void volume strongly affect subsequent dependence of pressure on temperature. Semiempirical method calculates operating conditions in electrochemical storage cells equipped with pressure-relief vents. Used to design cells to discharge safely and completely. Conceived for Li/SOCI2 cells, method applicable to other electrochemical cells.

  2. Nanocrystalline electrochemical solar cells

    SciTech Connect

    McEvoy, A.J.; Graetzel, M. [Ecole Polytechnique Federale, Lausanne (Switzerland). Inst. de Chimie-Physique; Wittkopf, H.; Jestel, D.; Benemann, J. [Flachglas AG, Gelsenkirchen (Germany)

    1994-12-31

    Standard solar cells exploit the physics of semiconductors in which the energy of absorbed photons excites charge-carrier pairs which are subsequently separated by the influence of a solid state junction to provide a photovoltage. In the nanocrystalline electrochemical cell, the optical absorber is a dye monolayer which after photo-excitation injects electrons into a semiconductor substrate, with charge neutrality being restored by a chemical redox reaction. The circuit is completed through an electrolyte and a metallic counterlectrode. Present performance, industrial engagement in research and development and commercial prospects are presented.

  3. Electrochemical cell with gelled anode

    SciTech Connect

    Bahary, W.S.

    1983-04-19

    An electrochemical cell having a gelled anode, wherein the gelling agent is an anionic polysaccharide having a rigid ordered structure such as extracellular microbial polysaccharides, particularly xanthan gum.

  4. Solid state electrochemical cell

    SciTech Connect

    Bannister, D.J.

    1984-09-11

    A solid state electrochemical cell comprises an anode having Li as its active material, a cathode and an electrolyte comprising a complex of a polyether with lithium. The polyether is atactic, has a low glass transition temperature and is capable of forming a complex with Li/sup +/ ions but not with Na/sup +/ ions. An example of such a polyether is polyvinyl methyl ether. The complex may be blended with another polymer such as a poly (ethyleneoxide) LiClO/sub 4/ comples to improve mechanical properties for fabrication into the enectrolyte.

  5. Miniaturized Electrochemical Flow Cells

    PubMed Central

    Sahlin, Eskil; Halle, Alexandra ter; Schaefer, Kathleen; Horn, Jeffery; Then, Matthew; Weber, Stephen G.

    2006-01-01

    Several novel types of miniaturized electrochemical flow cells are described. The flow cells are fabricated in fluorinated ethylene propylene using a novel technique where channels with inner diameters down to 13 ?m are integrated with electrodes. The channel is formed by shrinking and simultaneous melting of a heat shrink/melt tubing around a channel template (a tungsten wire) and electrodes followed by removal of the channel template. The technique allows incorporation of different electrode materials of different sizes. The electrode configuration consists of one or two working electrodes inside the channel and a counter electrode located in the channel outlet reservoir. Electrode configurations with different channel and working electrode sizes, different electrode materials including carbon fibers, glassy carbon rods, poly(tetrafluoroethylene)/carbon composite material, and platinum wires, and different arrangements have been assembled. Hydrodynamic voltammograms in dual-electrode (generator–collector) experiments indicate good potential control for cells with 25-?m channels, while there is some iR drop in cells with 13-?m channels. Cells prepared with a cylindrical working electrode tangent and perpendicular to a flow channel show a flow rate dependence consistent with thin-layer cell behavior. Electrode areas can be made in the range of 10?10–10?8 m2. PMID:12622401

  6. Method for manufacturing an electrochemical cell

    DOEpatents

    Kaun, Thomas D. (New Lenox, IL); Eshman, Paul F. (Bolingbrook, IL)

    1982-01-01

    A secondary electrochemical cell is prepared by providing positive and negative electrodes having outer enclosures of rigid perforated electrically conductive material defining an internal compartment containing the electrode material in porous solid form. The electrodes are each immersed in molten electrolyte salt prior to cell assembly to incorporate the cell electrolyte. Following solidification of the electrolyte substantially throughout the porous volume of the electrode material, the electrodes are arranged in an alternating positive-negative array with interelectrode separators of porous frangible electrically insulative material. The completed array is assembled into the cell housing and sealed such that on heating the solidified electrolyte flows into the interelectrode separator.

  7. Separator material for electrochemical cells

    DOEpatents

    Cieslak, W.R.; Storz, L.J.

    1991-03-26

    An electrochemical cell is characterized as utilizing an aramid fiber as a separator material. The aramid fibers are especially suited for lithium/thionyl chloride battery systems. The battery separator made of aramid fibers possesses superior mechanical strength, chemical resistance, and is flame retardant.

  8. Separator material for electrochemical cells

    DOEpatents

    Cieslak, Wendy R. (1166 Laurel Loop NE., Albuquerque, NM 87122); Storz, Leonard J. (2215 Ambassador NE., Albuquerque, NM 87112)

    1991-01-01

    An electrochemical cell characterized as utilizing an aramid fiber as a separator material. The aramid fibers are especially suited for lithium/thionyl chloride battery systems. The battery separator made of aramid fibers possesses superior mechanical strength, chemical resistance, and is flame retardant.

  9. Electrochemical sensor for monitoring electrochemical potentials of fuel cell components

    DOEpatents

    Kunz, Harold R. (Vernon, CT); Breault, Richard D. (Coventry, CT)

    1993-01-01

    An electrochemical sensor comprised of wires, a sheath, and a conduit can be utilized to monitor fuel cell component electric potentials during fuel cell shut down or steady state. The electrochemical sensor contacts an electrolyte reservoir plate such that the conduit wicks electrolyte through capillary action to the wires to provide water necessary for the electrolysis reaction which occurs thereon. A voltage is applied across the wires of the electrochemical sensor until hydrogen evolution occurs at the surface of one of the wires, thereby forming a hydrogen reference electrode. The voltage of the fuel cell component is then determined with relation to the hydrogen reference electrode.

  10. Compacted carbon for electrochemical cells

    DOEpatents

    Greinke, Ronald Alfred (Medina, OH); Lewis, Irwin Charles (Strongsville, OH)

    1997-01-01

    This invention provides compacted carbon that is useful in the electrode of an alkali metal/carbon electrochemical cell of improved capacity selected from the group consisting of: (a) coke having the following properties: (i) an x-ray density of at least 2.00 grams per cubic centimeters, (ii) a closed porosity of no greater than 5%, and (iii) an open porosity of no greater than 47%; and (b) graphite having the following properties: (i) an x-ray density of at least 2.20 grams per cubic centimeters, (ii) a closed porosity of no greater than 5%, and (iii) an open porosity of no greater than 25%. This invention also relates to an electrode for an alkali metal/carbon electrochemical cell comprising compacted carbon as described above and a binder. This invention further provides an alkali metal/carbon electrochemical cell comprising: (a) an electrode as described above, (b) a non-aqueous electrolytic solution comprising an organic aprotic solvent and an electrolytically conductive salt and an alkali metal, and (c) a counterelectrode.

  11. Advances in ambient temperature secondary lithium cells

    NASA Technical Reports Server (NTRS)

    Subbarao, S.; Shen, D. H.; Deligiannis, F.; Huang, C.-K.; Halpert, G.

    1990-01-01

    The goal of the NASA/OAST sponsored program on the development of ambient-temperature secondary lithium cells for future space applications is to develop cells with a 100 W h/kg specific energy and capable of 1000 cycles at 50-percent depth of discharge. This paper examines the performance potentials of Li-TiS2, Li-MoS3, Li-V6O13, and Li-NbSe3 electrochemical systems at ambient temperature, together with cycle life and safety characteristics. Of these four, the Li-TiS2 system was found to be the most promising in terms of achievable specific energy and cycle life. Major advances made on the development of secondary lithium cells, which are in the areas of cathode processing technology, mixed solvent electrolytes, and cell assembly, are summarized.

  12. Trends in Cell-Based Electrochemical Biosensors

    Microsoft Academic Search

    Lin Ding; Dan Du; Xueji Zhang; Huangxian Ju

    2008-01-01

    Cell-based electrochemical biosensors have contributed tremendously to the fields of biology, medicine, chem- istry, pharmacology, and environmental science. With electrochemical transducers and whole cells as the recognition ele- ments, these biosensors provide new horizons for biosensing and life science research. This review focuses on the re- search accomplishments on this topic over the last three years, and is divided into

  13. Electrochemical cell and negative electrode therefor

    DOEpatents

    Kaun, Thomas D. (New Lenox, IL)

    1982-01-01

    A secondary electrochemical cell with the positive and negative electrodes separated by a molten salt electrolyte with the negative electrode comprising a particulate mixture of lithium-aluminum alloy and electrolyte and an additive selected from graphitized carbon, Raney iron or mixtures thereof. The lithium-aluminum alloy is present in the range of from about 45 to about 80 percent by volume of the negative electrode, and the electrolyte is present in an amount not less than about 10 percent by volume of the negative electrode. The additive of graphitized carbon is present in the range of from about 1 to about 10 percent by volume of the negative electrode, and the Raney iron additive is present in the range of from about 3 to about 10 percent by volume of the negative electrode.

  14. Electrochemical cell having an alkali-metal-nitrate electrode

    DOEpatents

    Roche, M.F.; Preto, S.K.

    1982-06-04

    A power-producing secondary electrochemical cell includes a molten alkali metal as the negative-electrode material and a molten-nitrate salt as the positive-electrode material. The molten material in the respective electrodes are separated by a solid barrier of alkali-metal-ion conducting material. A typical cell includes active materials of molten sodium separated from molten sodium nitrate and other nitrates in mixture by a layer of sodium ..beta..'' alumina.

  15. Boundary Layer Analysis of Membraneless Electrochemical Cells

    E-print Network

    Braff, William

    A mathematical theory is presented for the charging and discharging behavior of membraneless electrochemical cells that rely on slow diffusion in laminar flow to separate the half reactions. Ion transport is described by ...

  16. Electrochemical cell for rebalancing REDOX flow system

    NASA Technical Reports Server (NTRS)

    Thaller, L. H. (inventor)

    1979-01-01

    An electrically rechargeable REDOX cell or battery system including one of more rebalancing cells is described. Each rebalancing cell is divided into two chambers by an ion permeable membrane. The first chamber is fed with gaseous hydrogen and a cathode fluid which is circulated through the cathode chamber of the REDOX cell is also passed through the second chamber of the rebalancing cell. Electrochemical reactions take place on the surface of insert electrodes in the first and second chambers to rebalance the electrochemical capacity of the anode and cathode fluids of the REDOX system.

  17. Electrochemical cell with electrode hold-down

    Microsoft Academic Search

    R. J. Boudrot; J. S. Shambaugh; H. Zeltzer

    1981-01-01

    A primary electrochemical cell including a hold-down unit for securing and preventing movement of a physically large battery stack of the cell is disclosed. The battery stack is disposed within a rectangular metal housing of the cell, together with an electrolytic solution, and comprises a large number of rectangular anodes and cathode structures arranged in the battery stack in alternation.

  18. Advances in ambient temperature secondary lithium cells

    NASA Technical Reports Server (NTRS)

    Subbarao, S.; Shen, D. H.; Deligiannis, F.; Huang, C-K.; Halpert, G.

    1989-01-01

    The Jet Propulsion Laboratory is involved in a Research and Development program sponsored by NASA/OAST on the development of ambient temperature secondary lithium cells for future space applications. Some of the projected applications are planetary spacecraft, planetary rovers, and astronaut equipment. The main objective is to develop secondary lithium cells with greater than 100 Wh/kg specific energy while delivering 1000 cycles at 50 percent Depth of Discharge (DOD). To realize these ambitious goals, the work was initially focused on several important basic issues related to the cell chemistry, selection of cathode materials and electrolytes, and component development. The performance potential of Li-TiS2, Li-MoS3, Li-V6O13 and Li-NbSe3 electrochemical systems was examined. Among these four, the Li-TiS2 system was found to be the most promising system in terms of realizable specific energy and cycle life. Some of the major advancements made so far in the development of Li-TiS2 cells are in the areas of cathode processing technology, mixed solvent electrolytes, and cell assembly. Methods were developed for the fabrication of large size high performance TiS2 cathodes. Among the various electrolytes examined, 1.5M LiAsF6/EC + 2-MeTHF mixed solvent electrolyte was found to be more stable towards lithium. Experimental cells activated with this electrolyte exhibited more than 300 cycles at 100 percent Depth of Discharge. Work is in progress in other areas such as selection of lithium alloys as candidate anode materials, optimization of cell design, and development of 5 Ah cells. The advances made at the Jet Propulsion Laboratory on the development of secondary lithium cells are summarized.

  19. Electrochemical noise in lithium primary cells

    NASA Astrophysics Data System (ADS)

    Donaldson, George J.; Nip, Wing S.; Patraboy, Timothy J.; Anderson, James S.; Farrington, Michael D.

    Electrochemical noise is interpreted as the occurrence of microscopic fluctuations of the potential of an electrochemical cell. A study was conducted on a number of commercial lithium cells to evaluate the practicality of electrochemical noise measurement as a diagnostic tool for performance and/or safety. The survey was limited to the following lithium based systems: sulfur dioxide, thionyl chloride, and manganese dioxide. The cells were subjected to a program of storage, environmental, and discharge conditions and then examined to determine whether there was any detectable effect on the electrochemical noise characteristics. While the study was of limited scope, it was nevertheless established that all cells exhibited some measurable electrochemical noise under certain conditions. The characteristics of the noise and its magnitude were influenced by many factors. The occurrence of observable noise above the instrumental background was generally associated with cells which had been discharged to between 80 and 100 percent of their nominal capacity. Most of the noise of interest was found at frequencies below 100 Hz.

  20. Highly sensitive bacteria quantification using immunomagnetic separation and electrochemical detection of Guanine-labeled secondary beads.

    PubMed

    Jayamohan, Harikrishnan; Gale, Bruce K; Minson, Bj; Lambert, Christopher J; Gordon, Neil; Sant, Himanshu J

    2015-01-01

    In this paper, we report the ultra-sensitive indirect electrochemical detection of E. coli O157:H7 using antibody functionalized primary (magnetic) beads for capture and polyguanine (polyG) oligonucleotide functionalized secondary (polystyrene) beads as an electrochemical tag. Vacuum filtration in combination with E. coli O157:H7 specific antibody modified magnetic beads were used for extraction of E. coli O157:H7 from 100 mL samples. The magnetic bead conjugated E. coli O157:H7 cells were then attached to polyG functionalized secondary beads to form a sandwich complex (magnetic bead/E. coli secondary bead). While the use of magnetic beads for immuno-based capture is well characterized, the use of oligonucleotide functionalized secondary beads helps combine amplification and potential multiplexing into the system. The antibody functionalized secondary beads can be easily modified with a different antibody to detect other pathogens from the same sample and enable potential multiplexing. The polyGs on the secondary beads enable signal amplification up to 10\\(^{8}\\) guanine tags per secondary bead (\\(7.5\\times10^{6}\\) biotin-FITC per secondary bead, 20 guanines per oligonucleotide) bound to the target (E. coli). A single-stranded DNA probe functionalized reduced graphene oxide modified glassy carbon electrode was used to bind the polyGs on the secondary beads. Fluorescent imaging was performed to confirm the hybridization of the complex to the electrode surface. Differential pulse voltammetry (DPV) was used to quantify the amount of polyG involved in the hybridization event with tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)\\(_{3}^{2+}\\)) as the mediator. The amount of polyG signal can be correlated to the amount of E. coli O157:H7 in the sample. The method was able to detect concentrations of E. coli O157:H7 down to 3 CFU/100 mL, which is 67 times lower than the most sensitive technique reported in literature. The signal to noise ratio for this work was 3. We also demonstrate the use of the protocol for detection of E. coli O157:H7 seeded in waste water effluent samples. PMID:26007743

  1. Highly Sensitive Bacteria Quantification Using Immunomagnetic Separation and Electrochemical Detection of Guanine-Labeled Secondary Beads

    PubMed Central

    Jayamohan, Harikrishnan; Gale, Bruce K.; Minson, Bj; Lambert, Christopher J.; Gordon, Neil; Sant, Himanshu J.

    2015-01-01

    In this paper, we report the ultra-sensitive indirect electrochemical detection of E. coli O157:H7 using antibody functionalized primary (magnetic) beads for capture and polyguanine (polyG) oligonucleotide functionalized secondary (polystyrene) beads as an electrochemical tag. Vacuum filtration in combination with E. coli O157:H7 specific antibody modified magnetic beads were used for extraction of E. coli O157:H7 from 100 mL samples. The magnetic bead conjugated E. coli O157:H7 cells were then attached to polyG functionalized secondary beads to form a sandwich complex (magnetic bead/E. coli/ secondary bead). While the use of magnetic beads for immuno-based capture is well characterized, the use of oligonucleotide functionalized secondary beads helps combine amplification and potential multiplexing into the system. The antibody functionalized secondary beads can be easily modified with a different antibody to detect other pathogens from the same sample and enable potential multiplexing. The polyGs on the secondary beads enable signal amplification up to 108 guanine tags per secondary bead (7.5 × 106 biotin-FITC per secondary bead, 20 guanines per oligonucleotide) bound to the target (E. coli). A single-stranded DNA probe functionalized reduced graphene oxide modified glassy carbon electrode was used to bind the polyGs on the secondary beads. Fluorescent imaging was performed to confirm the hybridization of the complex to the electrode surface. Differential pulse voltammetry (DPV) was used to quantify the amount of polyG involved in the hybridization event with tris(2,2?-bipyridine)ruthenium(II) ( Ru(bpy)32+) as the mediator. The amount of polyG signal can be correlated to the amount of E. coli O157:H7 in the sample. The method was able to detect concentrations of E. coli O157:H7 down to 3 CFU/100 mL, which is 67 times lower than the most sensitive technique reported in literature. The signal to noise ratio for this work was 3. We also demonstrate the use of the protocol for detection of E. coli O157:H7 seeded in waste water effluent samples. PMID:26007743

  2. Electrochemical control of cell and tissue polarity.

    PubMed

    Chang, Fred; Minc, Nicolas

    2014-01-01

    Localized ion fluxes at the plasma membrane provide electrochemical gradients at the cell surface that contribute to cell polarization, migration, and division. Ion transporters, local pH gradients, membrane potential, and organization are emerging as important factors in cell polarization mechanisms. The power of electrochemical effects is illustrated by the ability of exogenous electric fields to redirect polarization in cells ranging from bacteria, fungi, and amoebas to keratocytes and neurons. Electric fields normally surround cells and tissues and thus have been proposed to guide cell polarity in development, cancer, and wound healing. Recent studies on electric field responses in model systems and development of new biosensors provide new avenues to dissect molecular mechanisms. Here, we review recent advances that bring molecular understanding of how electrochemistry contributes to cell polarity in various contexts. PMID:25062359

  3. Heteroatom incorporated coke for electrochemical cell electrode

    DOEpatents

    Lewis, Irwin Charles (Strongsville, OH); Greinke, Ronald Alfred (Medina, OH)

    1997-01-01

    This invention relates to an electrode for a coke/alkali metal electrochemical cell comprising: (a) calcined coke particles: (i) that contain at least 0.5 weight percent of nitrogen heteroatoms and at least 1.0 weight percent sulfur heteroatoms, and (ii) that have an average particle size from 2 microns to 40 microns with essentially no particles being greater than 50 microns. (b) a binder This invention also relates to a coke/alkali metal electrochemical cell comprising: (a) an electrode as described above, (b) a non-aqueous electrolytic solution comprising an organic aprotic solvent and an electrically conductive salt, and (c) a counterelectrode.

  4. Heteroatom incorporated coke for electrochemical cell electrode

    DOEpatents

    Lewis, I.C.; Greinke, R.A.

    1997-06-17

    This invention relates to an electrode for a coke/alkali metal electrochemical cell comprising: (a) calcined coke particles: (1) that contain at least 0.5 weight percent of nitrogen heteroatoms and at least 1.0 weight percent sulfur heteroatoms, and (2) that have an average particle size from 2 microns to 40 microns with essentially no particles being greater than 50 microns and (b) a binder. This invention also relates to a coke/alkali metal electrochemical cell comprising: (a) an electrode as described above, (b) a non-aqueous electrolytic solution comprising an organic aprotic solvent and an electrically conductive salt, and (c) a counterelectrode. 5 figs.

  5. A high temperature molten salt thermal electrochemical cell

    Microsoft Academic Search

    Edward J. Plichta; Wishvender K. Behl

    1990-01-01

    This invention relates in general to a high temperature molten salt thermal electrochemical cell and in particular to such a cell including cobalt oxide (Co3O4) as the cathode material. High temperature molten salt thermal electrochemical cells are widely used as power sources for projectiles, rockets, bombs, mines, missiles, decoys, jammers, and torpedoes. These are also used as fuses. Thermal electrochemical

  6. Minimizing electrode contamination in an electrochemical cell

    DOEpatents

    Kim, Yu Seung; Zelenay, Piotr; Johnston, Christina

    2014-12-09

    An electrochemical cell assembly that is expected to prevent or at least minimize electrode contamination includes one or more getters that trap a component or components leached from a first electrode and prevents or at least minimizes them from contaminating a second electrode.

  7. Cathode for an electrochemical cell

    DOEpatents

    Bates, John B. (Oak Ridge, TN); Dudney, Nancy J. (Knoxville, TN); Gruzalski, Greg R. (Oak Ridge, TN); Luck, Christopher F. (Knoxville, TN)

    2001-01-01

    Described is a thin-film battery, especially a thin-film microbattery, and a method for making same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode. Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between -15.degree. C. and 150.degree. C.

  8. Electrolyte for an electrochemical cell

    DOEpatents

    Bates, John B. (Oak Ridge, TN); Dudney, Nancy J. (Knoxville, TN)

    1997-01-01

    Described is a thin-film battery, especially a thin-film microbattery, and a method for making same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte amorphous lithium phosphorus oxynitride which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between -15.degree. C. and 150.degree. C.

  9. Electrolyte for an electrochemical cell

    DOEpatents

    Bates, J.B.; Dudney, N.J.

    1997-01-28

    Described is a thin-film battery, especially a thin-film microbattery, and a method for making the same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte amorphous lithium phosphorus oxynitride which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between {minus}15 C and 150 C. 9 figs.

  10. Electrochemical cells having hydrogen gas absorbing agent

    Microsoft Academic Search

    F. E. Parsen; T. T. Yatabe

    1982-01-01

    An agent which absorbs hydrogen gas for electrochemical cells is made from an oxide of manganese and nickel, cobalt or iron. At temperatures above about 40°C., the oxide of manganese can be replaced by lead oxide. Hydrophobic binders can be added to the agent or the agent can be microencapsulated in water-impermeable but hydrogen-gas-permeable materials. The agent is preferably added

  11. Porous electronic current collector bodies for electrochemical cell configurations

    DOEpatents

    Pollack, William (Pittsburgh, PA); Reichner, Philip (Plum Borough, PA)

    1989-01-01

    A high-temperature, solid electrolyte electrochemical cell configuration is made comprising a plurality of elongated electrochemical cells 1, having inner electrodes 3, outer electrodes 6 and solid electrolyte 4 therebetween, the cells being electronically connected in series and parallel by flexible, porous, fibrous strips 7, where the strips contain flexible, electronically conductive fibers bonded together and coated with a refractory oxide, and where the oxide coating is effective to prevent additional bonding of fibers during electrochemical cell operation at high temperatures.

  12. High energy density electrochemical cell

    NASA Technical Reports Server (NTRS)

    Byrne, J. J.; Williams, D. L.

    1970-01-01

    Primary cell has an anode of lithium, a cathode containing dihaloisocyanuric acid, and a nonaqueous electrolyte comprised of a solution of lithium perchlorate in methyl formate. It produces an energy density of 213 watt hrs/lb and can achieve a high current density.

  13. Cycle life test. [of secondary spacecraft cells

    NASA Technical Reports Server (NTRS)

    Harkness, J. D.

    1977-01-01

    Statistical information concerning cell performance characteristics and limitations of secondary spacecraft cells is presented. Weaknesses in cell design as well as battery weaknesses encountered in various satellite programs are reported. Emphasis is placed on improving the reliability of space batteries.

  14. Solid oxide electrochemical cell fabrication process

    DOEpatents

    Dollard, Walter J. (Churchill Borough, PA); Folser, George R. (Lower Burrell, PA); Pal, Uday B. (Cambridge, MA); Singhal, Subhash C. (Murrysville, PA)

    1992-01-01

    A method to form an electrochemical cell (12) is characterized by the steps of thermal spraying stabilized zirconia over a doped lanthanum manganite air electrode tube (14) to provide an electrolyte layer (15), coating conductive particles over the electrolyte, pressurizing the outside of the electrolyte layer, feeding halide vapors of yttrium and zirconium to the outside of the electrolyte layer and feeding a source of oxygen to the inside of the electrolyte layer, heating to cause oxygen reaction with the halide vapors to close electrolyte pores if there are any and to form a metal oxide coating on and between the particles and provide a fuel electrode (16).

  15. Electrochemical Characteristics of Lithium Transition-Metal Oxide as an Anode Material in a Lithium Secondary Battery

    Microsoft Academic Search

    Chil-Hoon Doh; Bong-Soo Jin; Jung-Hwan Lim; Seong-In Moon

    2002-01-01

    Lithium transition-metal oxides (LiTMOs) such as LiCoO2 and LiMn2O4 were investigated for their use as anode material for the lithium secondary battery. Ni?Li0?LiPF6(lM, EC + DEC (1 : l))?LiTMO?Cu cell was fabricated and its electrochemical properties were examined. LiCoO2 and LiMn2O4 showed fairly good characteristics as anode material as well as cathode material. At the 1st cathodic process, LiCoO2 had

  16. Partial-Vacuum-Gasketed Electrochemical Corrosion Cell

    NASA Technical Reports Server (NTRS)

    Bonifas, Andrew P.; Calle, Luz M.; Hintze, Paul E.

    2006-01-01

    An electrochemical cell for making corrosion measurements has been designed to prevent or reduce crevice corrosion, which is a common source of error in prior such cells. The present cell (see figure) includes an electrolyte reservoir with O-ring-edged opening at the bottom. In preparation for a test, the reservoir, while empty, is pressed down against a horizontal specimen surface to form an O-ring seal. A purge of air or other suitable gas is begun in the reservoir, and the pressure in the reservoir is regulated to maintain a partial vacuum. While maintaining the purge and partial vacuum, and without opening the interior of the reservoir to the atmosphere, the electrolyte is pumped into the reservoir. The reservoir is then slowly lifted a short distance off the specimen. The level of the partial vacuum is chosen such that the differential pressure is just sufficient to keep the electrolyte from flowing out of the reservoir through the small O-ring/specimen gap. Electrochemical measurements are then made. Because there is no gasket (and, hence, no crevice between the specimen and the gasket), crevice corrosion is unlikely to occur.

  17. Cylindrical electrochemical cells with a diaphragm seal

    SciTech Connect

    Georgopoulos, P.

    1993-07-13

    A cylindrical electrochemical cell is described comprising an anode, a cathode and electrolyte contained in a cylindrical container, the container having an open end and a closed end; wherein the open end of the container is sealed with a seal assembly comprising: (a) a disc-shaped seal member, made from an electrically insulative material, having an outer edge wall connected via a base to a centrally located cylindrical hub that defines an orifice; which base has a ventable diaphragm portion and a nonventable diaphragm portion that is thicker than the ventable diaphragm portion; and wherein the ventable diaphragm portion joins the hub at an interface and becomes gradually thicker in the direction away from the interface toward the outer edge wall so that the ventable diaphragm portion is thinnest at the interface; and (b) a current collector extending through the orifice defined by the hub into the cell's interior to contact one of the cell's electrodes.

  18. Sensor apparatus using an electrochemical cell

    DOEpatents

    Thakur, Mrinal (1309 Gatewood Dr., Apt. 1703, Auburn, AL 36830)

    2002-01-01

    A novel technology for sensing mechanical quantities such as force, stress, strain, pressure and acceleration has been invented. This technology is based on a change in the electrochemically generated voltage (electromotive force) with application of force, stress, strain, pressure or acceleration. The change in the voltage is due to a change in the internal resistance of the electrochemical cell with a change in the relative position or orientation of the electrodes (anode and cathode) in the cell. The signal to be detected (e.g. force, stress, strain, pressure or acceleration) is applied to one of the electrodes to cause a change in the relative position or orientation between the electrodes. Various materials, solid, semisolid, gel, paste or liquid can be utilized as the electrolyte. The electrolyte must be an ion conductor. The examples of solid electrolytes include specific polymer conductors, polymer composites, ion conducting glasses and ceramics. The electrodes are made of conductors such as metals with dissimilar electronegativities. Significantly enhanced sensitivities, up to three orders of magnitude higher than that of comparable commercial sensors, are obtained. The materials are substantially less expensive than commercially used materials for mechanical sensors.

  19. Sensor apparatus using an electrochemical cell

    DOEpatents

    Thakur, Mrinal

    2003-07-01

    A method for sensing mechanical quantities such as force, stress, strain, pressure and acceleration is disclosed. This technology is based on a change in the electrochemically generated voltage (electromotive force) with application of force, stress, strain, pressure or acceleration. The change in the voltage is due to a change in the internal resistance of the electrochemical cell with a change in the relative position or orientation of the electrodes (anode and cathode) in the cell. The signal to be detected (e.g. force, stress, strain, pressure or acceleration) is applied to one of the electrodes to cause a change in the relative position or orientation between the electrodes. Various materials, solid, semisolid, gel, paste or liquid can be utilized as the electrolyte. The electrolyte must be an ion conductor. The examples of solid electrolytes include specific polymer conductors, polymer composites, ion conducting glasses and ceramics. The electrodes are made of conductors such as metals with dissimilar electro negativities. Significantly enhanced sensitivities, up to three orders of magnitude higher than that of comparable commercial sensors, are obtained. The materials are substantially less expensive than commercially used materials for mechanical sensors. An apparatus for sensing such mechanical quantities using materials such as doped 1,4 cis-polyisopropene and nafion. The 1,4 cis-polyisopropene may be doped with lithium perchlorate or iodine. The output voltage signal increases with an increase of the sensing area for a given stress. The device can be used as an intruder alarm, among other applications.

  20. Electrochemical cell and negative electrode therefor. [Li-Al anode

    SciTech Connect

    Kaun, T.D.

    1981-07-29

    A secondary electrochemical cell is described with the positive and negative electrodes separated by a molten salt electrolyte with the negative electrode comprising a particulate mixture of lithium-aluminum alloy and electrolyte and an additive selected from graphitized carbon, Raney iron or mixtures thereof. The lithium-aluminum alloy is present in the range of from about 45 to about 80% by volume of the negative electrode, and the electrolyte is present in an amount not less than about 10% by volume of the negative electrode. The additive of graphitized carbon is present in the range of from about 1 to about 10% by volume of the negative electrode, and the Raney iron additive is present in the range of from about 3 to about 10% by volume of the negative electrode.

  1. A high temperature molten salt thermal electrochemical cell

    NASA Astrophysics Data System (ADS)

    Plichta, Edward J.; Behl, Wishvender K.

    1990-02-01

    This invention relates in general to a high temperature molten salt thermal electrochemical cell and in particular to such a cell including cobalt oxide (Co3O4) as the cathode material. High temperature molten salt thermal electrochemical cells are widely used as power sources for projectiles, rockets, bombs, mines, missiles, decoys, jammers, and torpedoes. These are also used as fuses. Thermal electrochemical cells are reserve-type cells that can be activated by heating with a pyrotechnic heat source such as zirconium and barium chromate powders or mixtures of iron powder and potassium perchlorate.

  2. High-temperature molten-salt thermal electrochemical cell

    SciTech Connect

    Plichta, E.J.; Behl, W.K.

    1990-02-12

    This invention relates in general to a high temperature molten salt thermal electrochemical cell and in particular to such a cell including cobalt oxide (Co{sub 3}O{sub 4}) as the cathode material. High temperature molten salt thermal electrochemical cells are widely used as power sources for projectiles, rockets, bombs, mines, missiles, decoys, jammers and torpedoes. These are also used as fuses. Thermal electrochemical cells are reserve-type cells that can be activated by heating with a pyrotechnic heat source such as zirconium and barium chromate powders or mixtures of iron powder and potassium perchlorate.

  3. Secondary lithium cells for space applications

    Microsoft Academic Search

    S. Surampudi; D. H. Shen; C.-K. Huang; S. R. Narayanan; A. Attia; G. Halpert

    1992-01-01

    It is concluded that secondary lithium batteries are suitable for planetary missions requiring high specific energy, long active shelf life, and limited cycle life. Titanium disulfide cathode material meet all the requirements for rechargeable lithium cell, including high intrinsic reversibility and realizable specific energy. Secondary lithium technology is still evolving, although low capacity cells have been demonstrated and greater than

  4. Bacteriorhodopsin-based photo-electrochemical cell.

    PubMed

    Chu, Li-Kang; Yen, Chun-Wan; El-Sayed, Mostafa A

    2010-10-15

    A simple solution-based electrochemical cell has been constructed and successfully employed in the detection of the photoelectric response upon photoexcitation of bacteriorhodopsin (bR) without external bias. Commercially-available indium tin oxide (ITO) glasses served as the optical windows and electrodes. Small amounts of bR suspensions (?100 ?L) were utilized as the photovoltaic medium to generate the proton gradient between two half-cells separated by a molecular porous membrane. Continuous broadband visible light (?>380 nm) and a short-pulse 532-nm laser were employed for the photoexcitation of bR. Upon the modulated cw broadband irradiation, an instantaneous rise and decay of the current was observed. Our observations of the pH-dependent photocurrent are consistent with previous reports in a bR thin film configuration, which also showed a polarity inversion at pH 5-6. This is due to the change of the priority of the proton release and proton uptake in the photocycle of bR. Studies on the ionic strength effect were also carried out at different KCl concentrations, which resulted in the acceleration of the rise and decay of the photoelectric response. This was accompanied by a decrease in the stationary photocurrent at higher KCl concentrations in the broadband excitation experiments. The solution-based electrochemical cell uses aqueous medium, which is required for the completion of the bR proton pumping function. Due to the generation of the stationary current, it is advantageous to convert solar energy into electricity without the need of film-based photovoltaic devices with external bias. PMID:20719494

  5. Composite electrode for use in electrochemical cells

    DOEpatents

    Vanderborgh, N.E.; Huff, J.R.; Leddy, J.

    1987-10-16

    A porous composite electrode for use in electrochemical cells. The electrode has a first face and a second face defining a relatively thin section therebetween. The electrode is comprised of an ion conducting material, an electron conducting material, and an electrocatalyst. The volume concentration of the ion conducting material is greatest at the first face and is decreased across the section, while the volume concentration of the electron conducting material is greatest at the second face and decreases across the section of the electrode. Substantially all of the electrocatalyst is positioned within the electrode section in a relatively narrow zone where the rate of electron transport of the electrode is approximately equal to the rate of ion transport of the electrode. 4 figs., 1 tab.

  6. Electrochemical cell current requirements for toxic organic waste destruction in Ce(IV)-mediated electrochemical oxidation process

    Microsoft Academic Search

    Vasily V. Kokovkin; Sang Joon Chung; Subramanian Balaji; Manickam Matheswaran; Il-Shik Moon

    2007-01-01

    The electrochemical cell for cerium oxidation and reactor for organic destruction are the most important operation units for\\u000a the successful working mediated electrochemical oxidation (MEO) process. In this study, electrochemical cells with DSA electrodes\\u000a of two types, single stack and double stack connected in series, were used. The performances towards the electrochemical generation\\u000a of Ce(IV) in nitric acid media at

  7. Evaluation program for secondary spacecraft cells

    NASA Technical Reports Server (NTRS)

    Harkness, J. D.

    1978-01-01

    The results of life cycle tests of secondary spacecraft cells are summarized. Cells consisted of seven sample classifications ranging from 3.0 to 20 ampere-hours, 1326 nlc nickel cadmium, 183 silver cadmium, and 125 silver zinc sealed cells. Variables examined include load, charge control, and temperature conditions.

  8. Cell characteristics of various electrochemical photo-cells

    NASA Astrophysics Data System (ADS)

    Honda, K.; Fujishima, A.; Inoue, T.

    A description is presented of three types of electrochemical photocells with semiconductor photoelectrode/electrolyte junctions, classified according to the redox potentials in the solution species, and including a photoelectrolytic cell, a regenerative- and a heterogeneous-photovoltaic cell. Attention is given to sufficient solar absorption, separation of the photogenerated carriers, and rapid charge transfer at the electrode. Solar energy conversion efficiencies are presented. Design considerations include the following: (1) large output photovoltage based on good reversability of redox couples in the solution and large band bending of the semiconductor electrode; (2) sufficiently small resistance of the overall semiconductor-solution system; and (3) no filtering effect of the solution.

  9. Advances in the SERI-DOE electrochemical photovoltaic cell program

    NASA Astrophysics Data System (ADS)

    Wallace, W.; Noufi, R.; Deb, S.

    1981-05-01

    The electrochemical photovoltaic cell program to evaluate the photovoltaic energy conversion efficiency, stability and storage potential of amorphous and polycrystalline semiconductor/electrolyte systems is described. Technologies capable of the conversion of light energy into electrical energy either directly in regenerative electrochemical photovoltaic devices or indirectly in overall regenerative cyclic systems incorporating storage are described. The goal of the program is to develop and demonstrate the viability of low cost electrochemical photovoltaic cells competitive with solid state photovoltaic devices and photoelectrochemical storage systems competitive with battery connected photovoltaic array storage.

  10. Method for making an electrochemical cell

    DOEpatents

    Tuller, Harry L. (Wellesley, MA); Kramer, Steve A. (Somerville, MA); Spears, Marlene A. (Woburn, MA); Pal, Uday B. (Needham, MA)

    1996-01-01

    An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is provided.

  11. Method for making an electrochemical cell

    DOEpatents

    Tuller, H.L.; Kramer, S.A.; Spears, M.A.; Pal, U.B.

    1996-04-23

    An electrochemical device is described including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is provided. 17 figs.

  12. Thermal conductor for high-energy electrochemical cells

    DOEpatents

    Hoffman, Joseph A. (Minneapolis, MN); Domroese, Michael K. (South St. Paul, MN); Lindeman, David D. (Hudson, WI); Radewald, Vern E. (Austin, TX); Rouillard, Roger (Beloeil, CA); Trice, Jennifer L. (Eagan, MN)

    2000-01-01

    A thermal conductor for use with an electrochemical energy storage device is disclosed. The thermal conductor is attached to one or both of the anode and cathode contacts of an electrochemical cell. A resilient portion of the conductor varies in height or position to maintain contact between the conductor and an adjacent wall structure of a containment vessel in response to relative movement between the conductor and the wall structure. The thermal conductor conducts current into and out of the electrochemical cell and conducts thermal energy between the electrochemical cell and thermally conductive and electrically resistive material disposed between the conductor and the wall structure. The thermal conductor may be fabricated to include a resilient portion having one of a substantially C-shaped, double C-shaped, Z-shaped, V-shaped, O-shaped, S-shaped, or finger-shaped cross-section. An elastomeric spring element may be configured so as to be captured by the resilient conductor for purposes of enhancing the functionality of the thermal conductor. The spring element may include a protrusion that provides electrical insulation between the spring conductor and a spring conductor of an adjacently disposed electrochemical cell in the presence of relative movement between the cells and the wall structure. The thermal conductor may also be fabricated from a sheet of electrically conductive material and affixed to the contacts of a number of electrochemical cells.

  13. Method of doping interconnections for electrochemical cells

    DOEpatents

    Pal, Uday B. (Monroeville, PA); Singhal, Subhash C. (Murrysville, PA); Moon, David M. (Pittsburgh, PA); Folser, George R. (Lower Burrell, PA)

    1990-01-01

    A dense, electronically conductive interconnection layer 26 is bonded on a porous, tubular, electronically conductive air electrode structure 16, optionally supported by a ceramic support 22, by (A) forming a layer of oxide particles of at least one of the metals Ca, Sr, Co, Ba or Mg on a part 24 of a first surface of the air electrode 16, (B) heating the electrode structure, (C) applying a halide vapor containing at least lanthanum halide and chromium halide to the first surface and applying a source of oxygen to a second opposite surface of the air electrode so that they contact at said first surface, to cause a reaction of the oxygen and halide and cause a dense lanthanum-chromium oxide structure to grow, from the first electrode surface, between and around the oxide particles, where the metal oxide particles get incoporated into the lanthanum-chromium oxide structure as it grows thicker with time, and the metal ions in the oxide particles diffuse into the bulk of the lanthamum-chromium oxide structure, to provide a dense, top, interconnection layer 26 on top of the air electrode 16. A solid electrolyte layer 18 can be applied to the uncovered portion of the air electrode, and a fuel electrode 20 can be applied to the solid electrolyte, to provide an electrochemical cell 10.

  14. Steel refining with an electrochemical cell

    DOEpatents

    Blander, M.; Cook, G.M.

    1985-05-21

    Disclosed is an apparatus for processing a metallic fluid containing iron oxide, container for a molten metal including an electrically conductive refractory disposed for contact with the molten metal which contains iron oxide, an electrolyte in the form of a basic slag on top of the molten metal, an electrode in the container in contact with the slag electrically separated from the refractory, and means for establishing a voltage across the refractory and the electrode to reduce iron oxide to iron at the surface of the refractory in contact with the iron oxide containing fluid. A process is disclosed for refining an iron product containing not more than about 10% by weight sulfur, comprising providing an electrolyte of a slag containing one or more of calcium oxide, magnesium oxide, silica or alumina, providing a cathode of the iron product in contact with the electrolyte, providing an anode in contact with the electrolyte electrically separated from the cathode, and operating an electrochemical cell formed by the anode, the cathode and the electrolyte to separate oxygen or sulfur present in the iron product therefrom.

  15. Cell structure for electrochemical devices and method of making same

    DOEpatents

    Kaun, Thomas D. (320 Willow St., New Lenox, IL 60451)

    1993-01-01

    An electrochemical device comprises a plurality of cells, each cell including a laminate cell membrane, made up of a separator/electrolyte means interposed between alternating positive and negative electrodes, each type of electrode being respectively in common contact to a single current collector.

  16. Separation of CO 2 from flue gas using electrochemical cells

    Microsoft Academic Search

    Henry W. Pennline; Evan J. Granite; David R. Luebke; John R. Kitchin; James Landon; Lisa M. Weiland

    2010-01-01

    Past research with high temperature molten carbonate electrochemical cells has shown that carbon dioxide can be separated from flue gas streams produced by pulverized coal combustion for power generation. However, the presence of trace contaminants, i.e., sulfur dioxide and nitric oxides, will impact the electrolyte within the cell. If a lower temperature cell could be devised that would utilize the

  17. An electrochemical surface plasmon resonance imaging system targeting cell analysis

    NASA Astrophysics Data System (ADS)

    Zhang, L. L.; Chen, X.; Wei, H. T.; Li, H.; Sun, J. H.; Cai, H. Y.; Chen, J. L.; Cui, D. F.

    2013-08-01

    This paper presents an electrochemical-surface plasmon resonance imaging (EC-SPRI) system, enabling the characterization of optical and electrical properties of cells, simultaneously. The developed surface plasmon resonance (SPR) imaging system was capable of imaging micro cavities with a dimension of 10 ?m × 10 ?m and differentiated glycerol solutions with a group of refractive indices (RIs). Furthermore, the EC-SPRI system was used to image A549 cells, suggesting corresponding RI and morphology changes during the cell death process. In the end, electrochemical and SPR methods were used in combination, recording oxidation peaks of A549 cells in the cyclic voltage curves and SPR response unit increase, simultaneously.

  18. Electrochemical cell utilizing molten alkali metal electrode-reactant

    DOEpatents

    Virkar, Anil V. (Sandy, UT); Miller, Gerald R. (Salt Lake City, UT)

    1983-11-04

    An improved electrochemical cell comprising an additive-modified molten alkali metal electrode-reactant and/or electrolyte is disclosed. Various electrochemical cells employing a molten alkali metal, e.g., sodium, electrode in contact with a cationically conductive ceramic membrane experience a lower resistance and a lower temperature coefficient of resistance whenever small amounts of selenium are present at the interface of the electrolyte and the molten alkali metal. Further, cells having small amounts of selenium present at the electrolyte-molten metal interface exhibit less degradation of the electrolyte under long term cycling conditions.

  19. Secondary lithium cells for space applications

    NASA Astrophysics Data System (ADS)

    Surampudi, S.; Shen, D. H.; Huang, C.-K.; Narayanan, S. R.; Attia, A.; Halpert, G.

    1992-02-01

    It is concluded that secondary lithium batteries are suitable for planetary missions requiring high specific energy, long active shelf life, and limited cycle life. Titanium disulfide cathode material meet all the requirements for rechargeable lithium cell, including high intrinsic reversibility and realizable specific energy. Secondary lithium technology is still evolving, although low capacity cells have been demonstrated and greater than 700 cycle life was achieved. Work is in progress to improve the cycle life and safety of the electrolytes, alternate lithium anode, and the separators.

  20. Secondary lithium cells for space applications

    NASA Technical Reports Server (NTRS)

    Surampudi, S.; Shen, D. H.; Huang, C.-K.; Narayanan, S. R.; Attia, A.; Halpert, G.

    1992-01-01

    It is concluded that secondary lithium batteries are suitable for planetary missions requiring high specific energy, long active shelf life, and limited cycle life. Titanium disulfide cathode material meet all the requirements for rechargeable lithium cell, including high intrinsic reversibility and realizable specific energy. Secondary lithium technology is still evolving, although low capacity cells have been demonstrated and greater than 700 cycle life was achieved. Work is in progress to improve the cycle life and safety of the electrolytes, alternate lithium anode, and the separators.

  1. Electrochemical cells with beta alumina ceramic electrolyte material

    SciTech Connect

    Ansell, R.O.

    1983-11-08

    In an electrochemical cell, e.g. a sodium sulphur cell, employing tubular beta alumina ceramic material, the electrolyte is put under axial compression, for example using spring means, to reduce the risk of mechanical failure arising from tensile stress in the material.

  2. Reconstitution of a Secondary Cell Wall in a Secondary Cell Wall-Deficient Arabidopsis Mutant

    PubMed Central

    Sakamoto, Shingo; Mitsuda, Nobutaka

    2015-01-01

    The secondary cell wall constitutes a rigid frame of cells in plant tissues where rigidity is required. Deposition of the secondary cell wall in fiber cells contributes to the production of wood in woody plants. The secondary cell wall is assembled through co-operative activities of many enzymes, and their gene expression is precisely regulated by a pyramidal cascade of transcription factors. Deposition of a transmuted secondary cell wall in empty fiber cells by expressing selected gene(s) in this cascade has not been attempted previously. In this proof-of-concept study, we expressed chimeric activators of 24 transcription factors that are preferentially expressed in the stem, in empty fiber cells of the Arabidopsis nst1-1 nst3-1 double mutant, which lacks a secondary cell wall in fiber cells, under the control of the NST3 promoter. The chimeric activators of MYB46, SND2 and ANAC075, as well as NST3, reconstituted a secondary cell wall with different characteristics from those of the wild type in terms of its composition. The transgenic lines expressing the SND2 or ANAC075 chimeric activator showed increased glucose and xylose, and lower lignin content, whereas the transgenic line expressing the MYB46 chimeric activator showed increased mannose content. The expression profile of downstream genes in each transgenic line was also different from that of the wild type. This study proposed a new screening strategy to identify factors of secondary wall formation and also suggested the potential of the artificially reconstituted secondary cell walls as a novel raw material for production of bioethanol and other chemicals. PMID:25535195

  3. Continuous-feed electrochemical cell with nonpacking particulate electrode

    DOEpatents

    Cooper, John F. (Oakland, CA)

    1995-01-01

    An electrochemical cell providing full consumption of electrochemically active particles in a nonpacking, electrolyte-permeable bed has a tapered cell cavity bounded by two nonparallel surfaces separated by a distance that promotes bridging of particles across the cavity. The gap/particle size ratio is maintained as the particles are consumed, decrease in size, and travel from the point of entry to the narrower end of the cell. A cell of this configuration supports a bed of low packing density maintained in a dynamic steady state by alternate formation and collapse of particle bridges across the gap and associated voids over the entire active area of the cell. The cell design can be applied to refuelable zinc/air cells and zinc/ferrocyanide storage batteries.

  4. Continuous-feed electrochemical cell with nonpacking particulate electrode

    DOEpatents

    Cooper, J.F.

    1995-07-18

    An electrochemical cell providing full consumption of electrochemically active particles in a nonpacking, electrolyte-permeable bed has a tapered cell cavity bounded by two nonparallel surfaces separated by a distance that promotes bridging of particles across the cavity. The gap/particle size ratio is maintained as the particles are consumed, decrease in size, and travel from the point of entry to the narrower end of the cell. A cell of this configuration supports a bed of low packing density maintained in a dynamic steady state by alternate formation and collapse of particle bridges across the gap and associated voids over the entire active area of the cell. The cell design can be applied to refuelable zinc/air cells and zinc/ferrocyanide storage batteries. 6 figs.

  5. Secondary fuel cell. [electrolytically-regenerative hydrogen fuel cells

    Microsoft Academic Search

    R. J. Haas; D. C. Briggs

    1978-01-01

    This application discloses a secondary fuel cell having improved electrode zones. Each cell has two electrode zones each containing a pair of electrode structures. A first such electrode structure in each zone is more efficient in operation during discharge of the fuel cell. Electrical structure is provided so that the first electrode structures are utilized during charging of the fuel

  6. On the electrochemical reactivity and design of NiP2 negative electrodes for secondary Li-ion batteries

    E-print Network

    Boyer, Edmond

    commercialisation, rechargeable Li-ion batteries are widely accepted, and are becoming the main power source1 On the electrochemical reactivity and design of NiP2 negative electrodes for secondary Li-ion study of cubic and monoclinic NiP2 polymorphs towards Li, as candidate for anodic applications for Li-ion

  7. Investigation of Sickle-Cell Haemoglobin Polymerisation under Electrochemical Control

    PubMed Central

    Iqbal, Zeshan; Li, Matthew; McKendry, Rachel; Horton, Michael; Caruana, Daren J

    2013-01-01

    We describe an electrochemistry-based technique to control and monitor the polymerisation of sickle-cell haemoglobin (HbS). The polymerisation was monitored as a change in turbidity during the depletion of oxygen in a small volume custom-built thin-layer electrochemical cell. The cell allowed the investigation of HbS polymerisation as a function of HbS concentration, temperature and solution pH. We confirm that the oxygen was efficiently depleted using finite-element modelling to accurately recreate the electrochemical thin-layer cell. Understanding the nucleation and growth of HbS polymerisation will provide a better understanding of the pathophysiology of sickle-cell disease in vivo, and thus help improve therapeutic strategies for this common and frequently disabling disorder. PMID:23703945

  8. Electrode electrolyte interlayers containing cerium oxide for electrochemical fuel cells

    DOEpatents

    Borglum, Brian P. (Edgewood, PA); Bessette, Norman F. (N. Huntingdon, PA)

    2000-01-01

    An electrochemical cell is made having a porous fuel electrode (16) and a porous air electrode (13), with solid oxide electrolyte (15) therebetween, where the air electrode surface opposing the electrolyte has a separate, attached, dense, continuous layer (14) of a material containing cerium oxide, and where electrolyte (16) contacts the continuous oxide layer (14), without contacting the air electrode (13).

  9. Oxide modified air electrode surface for high temperature electrochemical cells

    DOEpatents

    Singh, Prabhakar (Export, PA); Ruka, Roswell J. (Churchill Boro, Allegheny County, PA)

    1992-01-01

    An electrochemical cell is made having a porous cermet electrode (16) and a porous lanthanum manganite electrode (14), with solid oxide electrolyte (15) between them, where the lanthanum manganite surface next to the electrolyte contains a thin discontinuous layer of high surface area cerium oxide and/or praseodymium oxide, preferably as discrete particles (30) in contact with the air electrode and electrolyte.

  10. Mass spectrometric methods for monitoring redox processes in electrochemical cells

    PubMed Central

    Oberacher, Herbert; Pitterl, Florian; Erb, Robert; Plattner, Sabine

    2015-01-01

    Electrochemistry (EC) is a mature scientific discipline aimed to study the movement of electrons in an oxidation–reduction reaction. EC covers techniques that use a measurement of potential, charge, or current to determine the concentration or the chemical reactivity of analytes. The electrical signal is directly converted into chemical information. For in-depth characterization of complex electrochemical reactions involving the formation of diverse intermediates, products and byproducts, EC is usually combined with other analytical techniques, and particularly the hyphenation of EC with mass spectrometry (MS) has found broad applicability. The analysis of gases and volatile intermediates and products formed at electrode surfaces is enabled by differential electrochemical mass spectrometry (DEMS). In DEMS an electrochemical cell is sampled with a membrane interface for electron ionization (EI)-MS. The chemical space amenable to EC/MS (i.e., bioorganic molecules including proteins, peptides, nucleic acids, and drugs) was significantly increased by employing electrospray ionization (ESI)-MS. In the simplest setup, the EC of the ESI process is used to analytical advantage. A limitation of this approach is, however, its inability to precisely control the electrochemical potential at the emitter electrode. Thus, particularly for studying mechanistic aspects of electrochemical processes, the hyphenation of discrete electrochemical cells with ESI-MS was found to be more appropriate. The analytical power of EC/ESI-MS can further be increased by integrating liquid chromatography (LC) as an additional dimension of separation. Chromatographic separation was found to be particularly useful to reduce the complexity of the sample submitted either to the EC cell or to ESI-MS. Thus, both EC/LC/ESI-MS and LC/EC/ESI-MS are common. PMID:24338642

  11. Development of ambient temperature secondary lithium cells

    NASA Technical Reports Server (NTRS)

    Subbarao, S.; Shen, D. H.; Dawson, S.; Deligiannis, F.; Taraszkiewicz, J.; Halpert, Gerald

    1987-01-01

    JPL is developing ambient temperature secondary lithium cells for future spacecraft applications. Prior studies on experimental laboratory type Li-TiS2 cells yielded promising results in terms of cycle life and rate capability. To further assess the performance of this cell, 5 Ah engineering model cells were developed. Initially baseline cells were designed and fabricated. Each cell had 15 cathodes and 16 anodes and the ratio of anode to cathode capacity is 6:1. A solution of 1.5 molar LiAsF6 in 2Me-THF was used as the electrolyte. Cells were evaluated for their cycle life at C/1 and C/5 discharge rates and 100 percent depth of discharge. The cells were cycled between voltage limits 1.7 and 2.8 volts. The rate of charge in all cases is C/10. The results obtained indicate that cells can operate at C/10 to C/2 discharge rates and have an initial energy density of 70 Wh/kg. Cells delivered more than 100 cycles at C/2 discharge rate. The details of cell design, the test program, and the results obtained are described.

  12. Development of ambient temperature secondary lithium cells

    NASA Technical Reports Server (NTRS)

    Subbarao, S.; Shen, D. H.; Dawson, S.; Deligiannis, F.; Taraszkiewicz, J.; Halpert, G.

    1988-01-01

    JPL is developing ambient temperature secondary lithium cells for future spacecraft applications. Prior studies on experimental laboratory type Li-TiS2 cells yielded promising results in terms of cycle life and rate capability. To further assess the performance of this cell, 5 Ah engineering model cells were developed. Initially baseline cells were designed and fabricated. Each cell had 15 cathodes and 16 anodes and the ratio of anode to cathode capacity is 6:1. A solution of 1.5 molar LiAsF6 in 2Me-THF was used as the electrolyte. Cells were evaluated for their cycle life at C/1 and C/5 discharge rates and 100 percent depth of discharge. The cells were cycled between voltage limits 1.7 and 2.8 volts. The rate of charge in all cases is C/10. The results obtained indicate that cells can operate at C/10 to C/2 discharge rates and have an initial energy density of 70 Wh/kg. Cells delivered more than 100 cycles at C/2 discharge rate. The details of cell design, the test program, and the results obtained are described.

  13. Facile and quantitative electrochemical detection of yeast cell apoptosis

    PubMed Central

    Yue, Qiulin; Xiong, Shiquan; Cai, Dongqing; Wu, Zhengyan; Zhang, Xin

    2014-01-01

    An electrochemical method based on square wave anodic stripping voltammetry (SWASV) was developed to detect the apoptosis of yeast cells conveniently and quantitatively through the high affinity between Cu2+ and phosphatidylserine (PS) translocated from the inner to the outer plasma membrane of the apoptotic cells. The combination of negatively charged PS and Cu2+ could decrease the electrochemical response of Cu2+ on the electrode. The results showed that the apoptotic rates of cells could be detected quantitatively through the variations of peak currents of Cu2+ by SWASV, and agreed well with those obtained through traditional flow cytometry detection. This work thus may provide a novel, simple, immediate and accurate detection method for cell apoptosis. PMID:24625374

  14. Electrochemical properties of electrospun poly(5-cyanoindole) submicron-fibrous electrode for zinc/polymer secondary battery

    NASA Astrophysics Data System (ADS)

    Cai, Zhijiang; Guo, Jie; Yang, Haizheng; Xu, Yi

    2015-04-01

    This study aims to develop an aqueous zinc/electrospun poly(5-cyanoindole) fibers secondary battery system. Zn foil and ZnCl2 are used as anode active materials and the electrolytic solution, respectively. Poly(5-cyanoindole) synthesized by chemical oxidation is electrospun into fibers and used as cathode active materials. FTIR and NMR test are carried out to investigate the chemical structure of poly(5-cyanoindole). Surface properties of electrospun poly(5-cyanoindole) fibers are studied by SEM, TEM, and BET. The performance of zinc/electrospun poly(5-cyanoindole) fibers battery system is evaluated in term of electrical conductivity, cyclic voltammogram, electrochemical impedance spectroscopy, discharge capacity and durability test. The cell achieves 2.0 V electromotive force with about 107-61 Ah Kg-1 discharge capacity at 0.2C-10C rate. At 800th cycle, the discharge capacity remains 80-57 Ah Kg-1 at 0.2C-2C rate, which is about 75-63% of the maximum discharge capacity. These results indicate that the cell has very excellent cyclic properties as well as fast charge/discharge properties. Electrospun poly(5-cyanoindole) fibers have been proved to be a better candidate than polyindole powder as cathode material in zinc/polymer battery.

  15. Testing and analyses of electrochemical cells using frequency response

    NASA Technical Reports Server (NTRS)

    Norton, O. A., Jr.; Thomas, D. L.

    1992-01-01

    The feasibility of electrochemical impedance spectroscopy as a method for analyzing battery state of health and state of charge was investigated. Porous silver, zinc, nickel, and cadmium electrodes as well as silver/zinc cells were studied. State of charge could be correlated with impedance data for all but the nickel electrodes. State of health was correlated with impedance data for two silver/zinc cells, one apparently good and the other dead. The experimental data were fit to equivalent circuit models.

  16. Testing and analyses of electrochemical cells using frequency response

    NASA Astrophysics Data System (ADS)

    Norton, O. A., Jr.; Thomas, D. L.

    1992-03-01

    The feasibility of electrochemical impedance spectroscopy as a method for analyzing battery state of health and state of charge was investigated. Porous silver, zinc, nickel, and cadmium electrodes as well as silver/zinc cells were studied. State of charge could be correlated with impedance data for all but the nickel electrodes. State of health was correlated with impedance data for two silver/zinc cells, one apparently good and the other dead. The experimental data were fit to equivalent circuit models.

  17. Cold pressed cadmium selenide photoanodes for electrochemical solar cells

    Microsoft Academic Search

    A. Mackintosh; S. Wessel; F. El Guibaly; K. Colbow

    1983-01-01

    Cold pressing of cadmium selenide powder was investigated as a technique for producing photoanodes for electrochemical solar cells. Physical properties such as density, resistivity and surface morphology were determined and related to solar cell performance via wavelength response, quantum efficiency and white light current-voltage characteristics. The spectral response indicated a bandgap of 1.7 eV. Pellets pressed at higher pressure showed

  18. Systems, methods and computer readable media for estimating capacity loss in rechargeable electrochemical cells

    DOEpatents

    Gering, Kevin L.

    2013-06-18

    A system includes an electrochemical cell, monitoring hardware, and a computing system. The monitoring hardware periodically samples charge characteristics of the electrochemical cell. The computing system periodically determines cell information from the charge characteristics of the electrochemical cell. The computing system also periodically adds a first degradation characteristic from the cell information to a first sigmoid expression, periodically adds a second degradation characteristic from the cell information to a second sigmoid expression and combines the first sigmoid expression and the second sigmoid expression to develop or augment a multiple sigmoid model (MSM) of the electrochemical cell. The MSM may be used to estimate a capacity loss of the electrochemical cell at a desired point in time and analyze other characteristics of the electrochemical cell. The first and second degradation characteristics may be loss of active host sites and loss of free lithium for Li-ion cells.

  19. Synthesis and electrochemical behavior of nanosized LiNi{sub 1-x}Ca {sub x}O{sub 2} cathode materials for high voltage secondary lithium-ion cells

    SciTech Connect

    Sathiyamoorthi, R. [Department of Industrial Chemistry, Alagappa University, Karaikudi 630003 (India); Vasudevan, T. [Department of Industrial Chemistry, Alagappa University, Karaikudi 630003 (India)]. E-mail: ramasathi25@yahoo.com

    2007-08-07

    A new class of LiNi{sub 1-x}Ca {sub x}O{sub 2} (x = 0.0, 0.1, 0.2, 0.3 and 0.5) layered oxide materials has been synthesized by a simple low temperature solid-state route with mixed nitrates/urea with glycerol as the starting materials. First we have taken TG/DTA for observing the phase transformations of LiNi{sub 0.9}Ca{sub 0.1}O{sub 2}. The structure of the synthesized oxides was analyzed using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) to identify the crystal structure and cation environment, respectively. The synthesized ceramic oxide battery materials were examined by using transmission electron microscope (TEM), scanning electron microscope (SEM) analysis to determine the particle size, nature and morphological structure. SEM with energy dispersive X-ray spectroscopic analysis (EDAX) analysis was carried out to explore the composition of the prepared materials. The electrochemical performance of LiNi{sub 1-x}Ca {sub x}O{sub 2} electrodes was analyzed using cyclic voltammetry (CV) and galvanostatic charge-discharge cycling studies in the voltage range 3.0-4.5 V. Electrode made with cathode active material, acetylene black and poly(vinylidene difluoride) yield a discharge capacity of 178.1 mAh g{sup -1} (x = 0.2) with good specific capacity over several charge-discharge cycles. These results have been also supported by cyclic voltammograms.

  20. Thermodynamics of Electrochemical Cells Chemistry 223

    E-print Network

    Ronis, David M.

    through the external circuit (doing work), and reenter the cell at the cathode, where one copper ion that functions as a battery, the so-called Galvanic or Daniels cell. Basically, when the switch is closed is reduced to copper metal. Thus, we can describe the redox chemistry in terms of the half-reactions: Zn Zn

  1. Protective interlayer for high temperature solid electrolyte electrochemical cells

    DOEpatents

    Isenberg, Arnold O. (Forest Hills Boro, PA); Ruka, Roswell J. (Churchill Boro, PA)

    1987-01-01

    A high temperature, solid electrolyte electrochemical cell is made, having a first and second electrode with solid electrolyte between them, where the electrolyte is formed by hot chemical vapor deposition, where a solid, interlayer material, which is electrically conductive, oxygen permeable, and protective of electrode material from hot metal halide vapor attack, is placed between the first electrode and the electrolyte, to protect the first electrode from the hot metal halide vapors during vapor deposition.

  2. Protective interlayer for high temperature solid electrolyte electrochemical cells

    DOEpatents

    Isenberg, Arnold O. (Forest Hills Boro, PA); Ruka, Roswell J. (Churchill Boro, PA); Zymboly, Gregory E. (Penn Hills Township, Allegheny County, PA)

    1985-01-01

    A high temperature, solid electrolyte electrochemical cell is made, having a first and second electrode with solid electrolyte between them, where the electrolyte is formed by hot chemical vapor deposition, where a solid, interlayer material, which is electrically conductive, oxygen permeable, and protective of electrode material from hot metal halide vapor attack, is placed between the first electrode and the electrolyte, to protect the first electrode from the hot metal halide vapors during vapor deposition.

  3. Protective interlayer for high temperature solid electrolyte electrochemical cells

    DOEpatents

    Isenberg, Arnold O. (Forest Hills Boro, PA); Ruka, Roswell J. (Churchill Boro, PA)

    1986-01-01

    A high temperature, solid electrolyte electrochemical cell is made, having a first and second electrode with solid electrolyte between them, where the electrolyte is formed by hot chemical vapor deposition, where a solid, interlayer material, which is electrically conductive, oxygen permeable, and protective of electrode material from hot metal halide vapor attack, is placed between the first electrode and the electrolyte, to protect the first electrode from the hot metal halide vapors during vapor deposition.

  4. Review of electrochemical impregnation for nickel cadmium cells. [aerospace applications

    NASA Technical Reports Server (NTRS)

    Gross, S.

    1977-01-01

    A method of loading active material within the electrodes of nickel cadmium cells is examined. The basic process of electrochemical impregnation of these electrodes is detailed, citing the principle that when current is applied reactions occur which remove hydrogen ions from solution, making the interior of the plaque less acidic. Electrodes result which are superior in energy density, stability, and life. The technology is reviewed and illustrated with typical performance data. Recommendations are made for additional research and development.

  5. Polymer-electrolyte membrane, electrochemical fuel cell, and related method

    DOEpatents

    Krishnan, Lakshmi; Yeager, Gary William; Soloveichik, Grigorii Lev

    2014-12-09

    A polymer-electrolyte membrane is presented. The polymer-electrolyte membrane comprises an acid-functional polymer, and an additive incorporated in at least a portion of the membrane. The additive comprises a fluorinated cycloaliphatic additive, a hydrophobic cycloaliphatic additive, or combinations thereof, wherein the additive has a boiling point greater than about 120.degree. C. An electrochemical fuel cell including the polymer-electrolyte membrane, and a related method, are also presented.

  6. Method of making gas diffusion layers for electrochemical cells

    DOEpatents

    Frisk, Joseph William (Oakdale, MN); Boand, Wayne Meredith (Lino Lakes, MN); Larson, James Michael (Saint Paul, MN)

    2002-01-01

    A method is provided for making a gas diffusion layer for an electrochemical cell comprising the steps of: a) combining carbon particles and one or more surfactants in a typically aqueous vehicle to make a preliminary composition, typically by high shear mixing; b) adding one or more highly fluorinated polymers to said preliminary composition by low shear mixing to make a coating composition; and c) applying the coating composition to an electrically conductive porous substrate, typically by a low shear coating method.

  7. A MEMS Photosynthetic Electrochemical Cell Powered by Subcellular Plant Photosystems

    Microsoft Academic Search

    Kien Bang Lam; Eric A. Johnson; Mu Chiao; Liwei Lin

    2006-01-01

    A microelectromechanical systems (MEMS) photosynthetic electrochemical cell$(mu PEC)$was demonstrated that harnesses the subcellular thylakoid photosystems isolated from spinach cells to convert light energy into electricity. Subject to light intensity of 2000$mu mol$photons\\/$ m ^2$\\/s, it generated an open circuit voltage (OCV) of 470 mV and a current density of 1.1$mu A\\/cm^2$at 5.2$mu V$. In the dark, the$mu PEC$continued to yield

  8. Fuel Cells and Electrochemical Energy Storage.

    ERIC Educational Resources Information Center

    Sammells, Anthony F.

    1983-01-01

    Discusses the nature of phosphoric acid, molten carbonate, and solid oxide fuel cells and major features and types of batteries used for electrical energy storage. Includes two tables presenting comparison of major battery features and summary of major material problems in the sodium-sulfur and lithium-alloy metal sulfide batteries. (JN)

  9. Electrochemical cell apparatus having an exterior fuel mixer nozzle

    DOEpatents

    Reichner, P.; Doshi, V.B.

    1992-12-08

    An electrochemical apparatus is made having a generator section containing electrochemical cells, a fresh gaseous feed fuel inlet, a gaseous feed oxidant inlet, and at least one hot gaseous spent fuel recirculation channel, where the spent fuel recirculation channel, a portion of which is in contact with the outside of a mixer chamber, passes from the generator chamber to combine with the fresh feed fuel inlet at the entrance to the mixer chamber, and a mixer nozzle is located at the entrance to the mixer chamber, where the mixer chamber connects with the reforming chamber, and where the mixer-diffuser chamber and mixer nozzle are exterior to and spaced apart from the combustion chamber, and the generator chamber, and the mixer nozzle can operate below 400 C. 2 figs.

  10. Electrochemical cell apparatus having an exterior fuel mixer nozzle

    DOEpatents

    Reichner, Philip (Plum Borough, PA); Doshi, Vinod B. (Monroeville, PA)

    1992-01-01

    An electrochemical apparatus (10) is made having a generator section (22) containing electrochemical cells (16), a fresh gaseous feed fuel inlet (28), a gaseous feed oxidant inlet (30), and at least one hot gaseous spent fuel recirculation channel (46), where the spent fuel recirculation channel (46), a portion of which is in contact with the outside of a mixer chamber (52), passes from the generator chamber (22) to combine with the fresh feed fuel inlet (28) at the entrance to the mixer chamber, and a mixer nozzle (50) is located at the entrance to the mixer chamber, where the mixer chamber (52) connects with the reforming chamber (54), and where the mixer-diffuser chamber (52) and mixer nozzle (50) are exterior to and spaced apart from the combustion chamber (24), and the generator chamber (22), and the mixer nozzle (50) can operate below 400.degree. C.

  11. Design of an Electrochemical Impedance Test Cell with Servomechanically Adjustable Cell Constant

    Microsoft Academic Search

    Hongshen Ma; Jeffrey H. Lang; Alexander H. Slocum

    2007-01-01

    This paper presents the design of an electrochemical impedance test cell for which the cell constant can be precisely varied so as to enable accurate, calibration-free measurements of the dielectric constant and conductivity of liquids and gases. This impedance test cell uses spherical electrodes separated by an adjustable small gap ranging from less than 1 mum up to 50 mum.

  12. Electrochemical storage cell based on polycrystalline silicon

    NASA Astrophysics Data System (ADS)

    Canfield, D.; Morrison, S. R.

    1982-02-01

    Theoretical and experimental investigations on the performance of n and p type silicon in solution for efficient solar energy conversion were conducted. Part of the work sought to identify redox couples capable of inducing maximum band bending (highest open circuit voltage) and limit the corrosion for both n and p type silicon. High photovoltages were obtained by using vanadium (II/III) and ferrocene/ferricinium couples for p type and n type silicon respectively. These couples demonstrated reasonable stability, but their efficiency was limited by the growth of a relatively thick insulating SiO2 corrosion layer. Corrosion studies were performed to evaluate the use of HF to remove the corrosion layer and to consider the interaction between HF and the redox couple. Much of the experimental and theoretical work focused on the effect of the surface oxide on solar cell characteristics and led to a variety of surface treatments aimed at improving the fill factor of silicon photoelectrochemical cells. The surface treatments included high temperature annealing of the normal oxide under an argon or hydrogen atmosphere, coating a p n junction with a thin layer of platinum, and passivation with poly-vinylcarbazole polymer.

  13. Exploratory studies on some electrochemical cell systems

    NASA Astrophysics Data System (ADS)

    Chaudhuri, Srikumar; Guha, D.

    Exploratory studies were conducted on cell systems with different metal anodes, and iodine and sulphur mixed with graphite powder in a polymer matrix as cathodes, using different electrolytes in non-aqueous and aqueous media as ionic charge carriers. The electrical conductance of the electrolyte solutions in aqueous and non-aqueous solvents, the open circuit voltage (OCV) and short circuit current (SCC) for the different cell systems were measured. To date, the non-aqueous solvents used in our studies were dimethylformamide, formamide, dioxan, and nitrobenzene, and the electrolytes used were potassium iodide, caustic potash, cetyltrimethylammonium bromide (CTAB), sodium lauryl sulphate (SLS) and calcium chloride. These electrolytes were used in both non-aqueous and aqueous media. In general, aqueous electrolyte solutions gave a better performance than non-aqueous electrolyte solutions. Of the aqueous electrolytes, the highest conductance was shown by potassium chloride solution in water (conductance=0.0334 mho). However, the best OCV and SCC were shown by aluminium as anode and iodine as cathode with a saturated solution of caustic potash in water. The OCV was 1.85 V and the SCC was 290 mA cm -2. The highest conductance among the non-aqueous systems was shown by caustic potash in formamide. (Conductance=0.013 mho.) The best OCV and SCC, however, were shown by a zinc anode and iodine cathode with saturated potassium chloride in formamide, having an OCV of 1.55 V and an SCC of 150 mA cm -2. Further studies are in progress to obtain detailed performance data and recharging characteristics of some of the more promising systems reported here.

  14. Method of electrode fabrication for solid oxide electrochemical cells

    DOEpatents

    Jensen, Russell R. (Murrysville, PA)

    1990-01-01

    A process for fabricating cermet electrodes for solid oxide electrochemical cells by sintering is disclosed. First, a porous metal electrode is fabricated on a solid oxide cell, such as a fuel cell by, for example, sintering, and is then infiltrated with a high volume fraction stabilized zirconia suspension. A second sintering step is used to sinter the infiltrated zirconia to a high density in order to more securely attach the electrode to the solid oxide electrolyte of the cell. High performance fuel electrodes can be obtained with this process. Further electrode performance enhancement may be achieved if stabilized zirconia doped with cerium oxide, chromium oxide, titanium oxide, and/or praseodymium oxide for electronic conduction is used.

  15. Improving light-emitting electrochemical cells with ionic additives

    NASA Astrophysics Data System (ADS)

    Shen, Yulong; Kuddes, Daniel D.; Naquin, Clint A.; Hesterberg, Travis W.; Kusmierz, Caroline; Holliday, Bradley J.; Slinker, Jason D.

    2013-05-01

    Light-emitting electrochemical cells with ionic transition metal complexes (iTMCs) comprising the active layer have great potential for lighting applications, but to date high luminance and fast turn on times have been challenging to attain without significant loss of lifetime. Here, we demonstrate iridium iTMC devices with high luminances of 3000-5000 cd/m2, reduced turn on times, and long lifetimes through incorporation of ionic additives. Furthermore, we show additional reduction of turn on time to seconds through heat processing. We rationalize these results as the enhancement of carrier injection through improved double-layer formation at the electrodes.

  16. In Vitro Electrochemical Corrosion and Cell Viability Studies on Nickel-Free Stainless Steel Orthopedic Implants

    PubMed Central

    Salahinejad, Erfan; Hadianfard, Mohammad Jafar; Macdonald, Digby Donald; Sharifi-Asl, Samin; Mozafari, Masoud; Walker, Kenneth J.; Rad, Armin Tahmasbi; Madihally, Sundararajan V.; Tayebi, Lobat

    2013-01-01

    The corrosion and cell viability behaviors of nanostructured, nickel-free stainless steel implants were studied and compared with AISI 316L. The electrochemical studies were conducted by potentiodynamic polarization and electrochemical impedance spectroscopic measurements in a simulated body fluid. Cytocompatibility was also evaluated by the adhesion behavior of adult human stem cells on the surface of the samples. According to the results, the electrochemical behavior is affected by a compromise among the specimen's structural characteristics, comprising composition, density, and grain size. The cell viability is interpreted by considering the results of the electrochemical impedance spectroscopic experiments. PMID:23630603

  17. Scanning electrochemical cell microscopy platform for ultrasensitive photoelectrochemical imaging.

    PubMed

    Aaronson, Barak D B; Byers, Joshua C; Colburn, Alex W; McKelvey, Kim; Unwin, Patrick R

    2015-04-21

    The development of techniques for nanoscale structure-activity correlations is of major importance for the fundamental understanding and rational design of (photo)electrocatalysts. However, the low conversion efficiency of characteristic materials generates tiny photoelectrochemical currents at the submicrometer to nanoscale, in the fA range, which are challenging to detect and measure accurately. Here, we report the coupling of scanning electrochemical cell microscopy (SECCM) with photoillumination, to create a submicrometer spatial resolution cell that opens up high resolution structure-(photo)activity measurements. We demonstrate the capabilities of the technique as a tool for: (i) high spatial resolution (photo)activity mapping using an ionic liquid electrolyte at a thin film of TiO2 aggregates, commonly used as a photoanode in dye sensitized solar cells (DSSCs) and (ii) in situ (photo)activity measurements of an electropolymerized conjugated polymer on a transparent Au substrate in a controlled atmospheric environment. Quantitative data, including localized (photo)electrochemical transients and external quantum efficiency (EQE), are extracted, and prospects for further technique development and enhancement are outlined. PMID:25797893

  18. Electrochemically Reduced Water Protects Neural Cells from Oxidative Damage

    PubMed Central

    Hamasaki, Takeki; Kinjo, Tomoya; Nakamichi, Noboru; Teruya, Kiichiro; Kabayama, Shigeru

    2014-01-01

    Aging-related neurodegenerative disorders are closely associated with mitochondrial dysfunction and oxidative stresses and their incidence tends to increase with aging. Brain is the most vulnerable to reactive species generated by a higher rate of oxygen consumption and glucose utilization compared to other organs. Electrochemically reduced water (ERW) was demonstrated to scavenge reactive oxygen species (ROS) in several cell types. In the present study, the protective effect of ERW against hydrogen peroxide (H2O2) and nitric oxide (NO) was investigated in several rodent neuronal cell lines and primary cells. ERW was found to significantly suppress H2O2 (50–200??M) induced PC12 and SFME cell deaths. ERW scavenged intracellular ROS and exhibited a protective effect against neuronal network damage caused by 200??M H2O2 in N1E-115 cells. ERW significantly suppressed NO-induced cytotoxicity in PC12 cells despite the fact that it did not have the ability to scavenge intracellular NO. ERW significantly suppressed both glutamate induced Ca2+ influx and the resulting cytotoxicity in primary cells. These results collectively demonstrated for the first time that ERW protects several types of neuronal cells by scavenging ROS because of the presence of hydrogen and platinum nanoparticles dissolved in ERW. PMID:25383141

  19. In Proc of Direct Methanol Fuel Cell Symposium, 199th Electrochem.l Soc. Mtg, Washington DC, 3/01.

    E-print Network

    Wang, Chao-Yang

    In Proc of Direct Methanol Fuel Cell Symposium, 199th Electrochem.l Soc. Mtg, Washington DC, 3 and high #12;In Proc of Direct Methanol Fuel Cell Symposium, 199th Electrochem.l Soc. Mtg, Washington DC, 3

  20. Electrochemical Desorption of Self-Assembled Monolayers Noninvasively Releases Patterned Cells from Geometrical Confinements

    E-print Network

    Mrksich, Milan

    Electrochemical Desorption of Self-Assembled Monolayers Noninvasively Releases Patterned Cells from on the electrochemical desorption of self-assembled monolayers (SAMs) to release pat- terned mammalian cells from steel electrode) on gold caused the SAMs to desorb.5,6 Removal of EG3-terminated SAMs from a gold

  1. Microfabricated Electrochemical Cell-Based Biosensors for Analysis of Living Cells In Vitro

    PubMed Central

    Wang, Jun; Wu, Chengxiong; Hu, Ning; Zhou, Jie; Du, Liping; Wang, Ping

    2012-01-01

    Cellular biochemical parameters can be used to reveal the physiological and functional information of various cells. Due to demonstrated high accuracy and non-invasiveness, electrochemical detection methods have been used for cell-based investigation. When combined with improved biosensor design and advanced measurement systems, the on-line biochemical analysis of living cells in vitro has been applied for biological mechanism study, drug screening and even environmental monitoring. In recent decades, new types of miniaturized electrochemical biosensor are emerging with the development of microfabrication technology. This review aims to give an overview of the microfabricated electrochemical cell-based biosensors, such as microelectrode arrays (MEA), the electric cell-substrate impedance sensing (ECIS) technique, and the light addressable potentiometric sensor (LAPS). The details in their working principles, measurement systems, and applications in cell monitoring are covered. Driven by the need for high throughput and multi-parameter detection proposed by biomedicine, the development trends of electrochemical cell-based biosensors are also introduced, including newly developed integrated biosensors, and the application of nanotechnology and microfluidic technology. PMID:25585708

  2. Microfabricated electrochemical cell-based biosensors for analysis of living cells in vitro.

    PubMed

    Wang, Jun; Wu, Chengxiong; Hu, Ning; Zhou, Jie; Du, Liping; Wang, Ping

    2012-01-01

    Cellular biochemical parameters can be used to reveal the physiological and functional information of various cells. Due to demonstrated high accuracy and non-invasiveness, electrochemical detection methods have been used for cell-based investigation. When combined with improved biosensor design and advanced measurement systems, the on-line biochemical analysis of living cells in vitro has been applied for biological mechanism study, drug screening and even environmental monitoring. In recent decades, new types of miniaturized electrochemical biosensor are emerging with the development of microfabrication technology. This review aims to give an overview of the microfabricated electrochemical cell-based biosensors, such as microelectrode arrays (MEA), the electric cell-substrate impedance sensing (ECIS) technique, and the light addressable potentiometric sensor (LAPS). The details in their working principles, measurement systems, and applications in cell monitoring are covered. Driven by the need for high throughput and multi-parameter detection proposed by biomedicine, the development trends of electrochemical cell-based biosensors are also introduced, including newly developed integrated biosensors, and the application of nanotechnology and microfluidic technology. PMID:25585708

  3. Dynamic doping in bright and stable light emitting electrochemical cells.

    PubMed

    Tordera, Daniel; Lenes, Martijn; Bolink, Henk J

    2013-07-01

    By using fast current density and luminance versus voltage (JL-V) analysis the device operation of sandwiched light emitting electrochemical cells (LECs) during their normal voltage driving operation mode is studied. In LECs the application of a voltage results in the movement of ions changing the state of the device, as a result the JL-V scans need to be performed fast and meet certain conditions to be meaningful. Space-charge limited current behavior is observed once the injection barriers are overcome. The increase of the current density after this point imply that the effective thickness of the devices is reduced which indicates the formation of more conductive regions adjacent to the electrodes. The increase in conductivity is a consequence of compensation of the injected electrons by dissociated ions that effectively increase the carrier concentration similar like in electrochemically doped semiconductors. The extension of the dynamically doped regions can be controlled by applying a pulsed current driving scheme which allows for both sub-second turn-on time and long lifetimes. PMID:23901548

  4. Fabrication of solid oxide fuel cell by electrochemical vapor deposition

    DOEpatents

    Riley, B.; Szreders, B.E.

    1988-04-26

    In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (/approximately/1100/degree/ /minus/ 1300/degree/C) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20--50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

  5. Fabrication of solid oxide fuel cell by electrochemical vapor deposition

    DOEpatents

    Brian, Riley (Willimantic, CT); Szreders, Bernard E. (Oakdale, CT)

    1989-01-01

    In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (approximately 1100.degree.-1300.degree. C.) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20-50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

  6. Electrochemically Deposited Ceria Structures for Advanced Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Brown, Evan C.

    As the pursuit towards emissions reduction intensifies with growing interest and nascent technologies, solid oxide fuel cells (SOFCs) remain an illustrious candidate for achieving our goals. Despite myriad advantages, SOFCs are still too costly for widespread deployment, even as unprecedented materials developments have recently emerged. This suggests that, in addition to informed materials selection, the necessary power output--and, thereby, cost-savings--gains must come from the fuel cell architecture. The work presented in this manuscript primarily investigates cathodic electrochemical deposition (CELD) as a scalable micro-/nanoscale fabrication tool for engineering ceria-based components in a SOFC assembly. Also, polymer sphere lithography was utilized to deposit fully connected, yet fully porous anti-dot metal films on yttira-stabilized zirconia (YSZ) with specific and knowable geometries, useful for mechanistic studies. Particular attention was given to anode structures, for which anti-dot metal films on YSZ served as composite substrates for subsequent CELD of doped ceria. By tuning the applied potential, a wide range of microstructures from high surface area coatings to planar, thin films was possible. In addition, definitive deposition was shown to occur on the electronically insulating YSZ surfaces, producing quality YSZ|ceria interfaces. These CELD ceria deposits exhibited promising electrochemical activity, as probed by A.C. Impedance Spectroscopy. In an effort to extend its usefulness as a SOFC fabrication tool, the CELD of ceria directly onto common SOFC cathode materials without a metallic phase was developed, as well as templated deposition schemes producing ceria nanowires and inverse opals.

  7. Method for transferring thermal energy and electrical current in thin-film electrochemical cells

    DOEpatents

    Rouillard, Roger (Beloeil, CA); Domroese, Michael K. (South St. Paul, MN); Hoffman, Joseph A. (Minneapolis, MN); Lindeman, David D. (Hudson, WI); Noel, Joseph-Robert-Gaetan (St-Hubert, CA); Radewald, Vern E. (Austin, TX); Ranger, Michel (Lachine, CA); Sudano, Anthony (Laval, CA); Trice, Jennifer L. (Eagan, MN); Turgeon, Thomas A. (Fridley, MN)

    2003-05-27

    An improved electrochemical generator is disclosed. The electrochemical generator includes a thin-film electrochemical cell which is maintained in a state of compression through use of an internal or an external pressure apparatus. A thermal conductor, which is connected to at least one of the positive or negative contacts of the cell, conducts current into and out of the cell and also conducts thermal energy between the cell and thermally conductive, electrically resistive material disposed on a vessel wall adjacent the conductor. The thermally conductive, electrically resistive material may include an anodized coating or a thin sheet of a plastic, mineral-based material or conductive polymer material. The thermal conductor is fabricated to include a resilient portion which expands and contracts to maintain mechanical contact between the cell and the thermally conductive material in the presence of relative movement between the cell and the wall structure. The electrochemical generator may be disposed in a hermetically sealed housing.

  8. Nanopillar based electrochemical biosensor for monitoring microfluidic based cell culture

    NASA Astrophysics Data System (ADS)

    Gangadharan, Rajan

    In-vitro assays using cultured cells have been widely performed for studying many aspects of cell biology and cell physiology. These assays also form the basis of cell based sensing. Presently, analysis procedures on cell cultures are done using techniques that are not integrated with the cell culture system. This approach makes continuous and real-time in-vitro measurements difficult. It is well known that the availability of continuous online measurements for extended periods of time will help provide a better understanding and will give better insight into cell physiological events. With this motivation we developed a highly sensitive, selective and stable microfluidic electrochemical glucose biosensor to make continuous glucose measurements in cell culture media. The performance of the microfluidic biosensor was enhanced by adding 3D nanopillars to the electrode surfaces. The microfluidic glucose biosensor consisted of three electrodes---Enzyme electrode, Working electrode, and Counter electrode. All these electrodes were enhanced with nanopillars and were optimized in their respective own ways to obtain an effective and stable biosensing device in cell culture media. For example, the 'Enzyme electrode' was optimized for enzyme immobilization via either a polypyrrole-based or a self-assembled-monolayer-based immobilization method, and the 'Working electrode' was modified with Prussian Blue or electropolymerized Neutral Red to reduce the working potential and also the interference from other interacting electro-active species. The complete microfluidic biosensor was tested for its ability to monitor glucose concentration changes in cell culture media. The significance of this work is multifold. First, the developed device may find applications in continuous and real-time measurements of glucose concentrations in in-vitro cell cultures. Second, the development of a microfluidic biosensor will bring technical know-how toward constructing continuous glucose monitoring devices. Third, the methods used to develop 3D electrodes incorporated with nanopillars can be used for other applications such as neural probes, fuel cells, solar cells etc., and finally, the knowledge obtained from the immobilization of enzymes onto nanostructures sheds some new insight into nanomaterial/biomolecule interactions.

  9. Electroendocytosis Is Driven by the Binding of Electrochemically Produced Protons to the Cell’s Surface

    PubMed Central

    Ben-Dov, Nadav; Rozman Grinberg, Inna; Korenstein, Rafi

    2012-01-01

    Electroendocytosis involves the exposure of cells to pulsed low electric field and is emerging as a complementary method to electroporation for the incorporation of macromolecules into cells. The present study explores the underlying mechanism of electroendocytosis and its dependence on electrochemical byproducts formed at the electrode interface. Cell suspensions were exposed to pulsed low electric field in a partitioned device where cells are spatially restricted relative to the electrodes. The cellular uptake of dextran-FITC was analyzed by flow cytometery and visualized by confocal microscopy. We first show that uptake occurs only in cells adjacent to the anode. The enhanced uptake near the anode is found to depend on electric current density rather than on electric field strength, in the range of 5 to 65 V/cm. Electrochemically produced oxidative species that impose intracellular oxidative stress, do not play any role in the stimulated uptake. An inverse dependence is found between electrically induced uptake and the solution’s buffer capacity. Electroendocytosis can be mimicked by chemically acidifying the extracellular solution which promotes the enhanced uptake of dextran polymers and the uptake of plasmid DNA. Electrochemical production of protons at the anode interface is responsible for inducing uptake of macromolecules into cells exposed to a pulsed low electric field. Expanding the understanding of the mechanism involved in electric fields induced drug-delivery into cells, is expected to contribute to clinical therapy applications in the future. PMID:23209699

  10. Non-faradaic electrochemical modification of catalytic activity in solid electrolyte cells

    Microsoft Academic Search

    C. G. Vayenas; S. Bebelis; S. Neophytides; I. V. Yentekakis

    1989-01-01

    The catalytic activity and selectivity of metal catalysts used as electrodes in high temperature solid electrolyte cells can be altered dramatically and in a reversible manner. This is accomplished by electrochemically supplying oxygen anions onto catalytic surfaces via polarized metal-solid electrolyte interfaces. Oxygen anions, forced electrochemically to adsorb on the metal catalyst surface, alter the catalyst work function in a

  11. Supported liquid membrane electrochemical separators

    DOEpatents

    Pemsler, J. Paul (Lexington, MA); Dempsey, Michael D. (Revere, MA)

    1986-01-01

    Supported liquid membrane separators improve the flexibility, efficiency and service life of electrochemical cells for a variety of applications. In the field of electrochemical storage, an alkaline secondary battery with improved service life is described in which a supported liquid membrane is interposed between the positive and negative electrodes. The supported liquid membranes of this invention can be used in energy production and storage systems, electrosynthesis systems, and in systems for the electrowinning and electrorefining of metals.

  12. Electrochemical study of nanometric Si on carbon for lithium ion secondary batteries

    NASA Astrophysics Data System (ADS)

    Doh, Chil-Hoon; Lee, Jung-Hoon; Lee, Duck-Jun; Kim, Ju-Seok; Jin, Bong-Soo; Moon, Seong-In; Hwang, Young-Ki; Park, Cheol-Wan

    2010-05-01

    The electrochemical and thermochemical properties of a silicon-graphite composite anode for lithium ion batteries were evaluated. The electrochemical properties were varied by the condition of pretreatment. The electrochemical pretreatment of constant current (C/10) and constant potential for 24 h showed specific discharge and charge capacities of 941 and 781 mA h g-1 to give a specific irreversible capacity of 161 mA h g-1 and a coulombic efficiency of 83%. The initial cycle as the next cycle of pretreatment showed a specific charge capacity (Li desertion) of 698 mA h g-1 and a coulombic efficiency of 95%. Coulombic efficiency at the fifth cycle was 97% to clear up almost all of the irreversible capacity. During the pretreatment cycle to the fourth cycle, the average specific charge capacity was 683 mA h g-1 and the cumulative irreversible capacity was 264 mA h g-1. Exothermic heat values based on the specific capacity of the discharged (Li insertion) electrode of silicon-graphite composite for the temperature range of 50-300 °C were 2.09 and 2.21 J mA-1h-1 for 0 and 2 h as time of pretreatment in the case of just disassembled wet electrodes and 1.43 and 1.01 J mA-1h-1 for 12 and 24 h as time of pretreatment in the case of dried electrodes, respectively.

  13. The Sodium Exposure Test Cell to determine operating parameters for AMTEC electrochemical cells

    SciTech Connect

    Ryan, M.A.; Williams, R.M.; Lara, L.; Cortez, R.H.; Homer, M.L.; Shields, V.B.; Miller, J.; Manatt, K.S.

    1998-07-01

    The Sodium Exposure Test Cell (SETC) is a non-power producing cell which has been developed to evaluate and test components of the electrochemical cell in an Alkali Metal Thermal to Electric Converter. Performance and time dependence of performance of the electrode and the electrolyte in AMTEC cells can be tested in an SETC, and performance parameters which correlate with those taken from AMTEC operation can be calculated from data taken in an SETC. The components of the AMTEC electrochemical cell which are evaluated in an SETC are the electrode, {beta}{double{underscore}prime}-alumina solid electrolyte (BASE), the current collection network, and the containment. The components are held in low pressure sodium vapor at a temperature which reflects their operating conditions in an AMTEC device, and operating parameters determined. Electrodes and BASE are evaluated by measuring current-voltage (IV) characteristics and using Electrochemical Impedance Spectroscopy (EIS). Using these techniques, electrode performance parameters such as the exchange current (B), the morphology factor (G), and contact resistance between electrode and current collection network can be determined. The ionic conductivity (s) of BASE can also be determined. IV curves and EIS measurements are made at intervals over periods of several hundreds of hours in order to evaluate degradation of AMTEC electrochemical cell components. Electrode and BASE are analyzed after an SETC experiment using Scanning Electron Microscopy, Electron Dispersive Spectroscopy, and X-Ray Diffraction. These techniques allow evaluation of interaction of materials and changes in the composition and structure of materials. The purpose of these experiments is determination of the changes of operating parameters as a function of time in order to predict the operating lifetime of AMTEC cells.

  14. The sealed nickel-hydrogen secondary cell

    Microsoft Academic Search

    Jose Giner; J. D. Dunlop

    1975-01-01

    A recently developed sealed nickel-hydrogen cell offers considerable promise to develop lightweight, long-life, rechargeable batteries. The most apparent advantages of this cell are its higher energy and power density as compared with other rechargeable systems including nickel-cadmium, lead-acid, and silver-zinc cells and the regenerative H2-O2 fuel cell. The energy density for lightweight 50 A-hr cells shown is 28 W-hr\\/lb. The

  15. Air electrode material for high temperature electrochemical cells

    DOEpatents

    Ruka, Roswell J. (Churchill Boro, PA)

    1985-01-01

    Disclosed is a solid solution with a perovskite-like crystal structure having the general formula La.sub.1-x-w (M.sub.L).sub.x (Ce).sub.w (M.sub.S1).sub.1-y (M.sub.S2).sub.y O.sub.3 where M.sub.L is Ca, Sr, Ba, or mixtures thereof, M.sub.S1 is Mn, Cr, or mixtures thereof and M.sub.S2 is Ni, Fe, Co, Ti, Al, In, Sn, Mg, Y, Nb, Ta, or mixtures thereof, w is about 0.05 to about 0.25, x+w is about 0.1 to about 0.7, and y is 0 to about 0.5. In the formula, M.sub.L is preferably Ca, w is preferably 0.1 to 0.2, x+w is preferably 0.4 to 0.7, and y is preferably 0. The solid solution can be used in an electrochemical cell where it more closely matches the thermal expansion characteristics of the support tube and electrolyte of the cell.

  16. Electrochemical in situ reaction cell for X-ray scattering, diffraction and spectroscopy.

    PubMed

    Braun, A; Shrout, S; Fowlks, A C; Osaisai, B A; Seifert, S; Granlund, E; Cairns, E J

    2003-07-01

    A versatile electrochemical in situ reaction cell for long-term hard X-ray experiments on battery electrodes is described. Applications include the small-angle scattering, diffraction and absorption spectroscopy of lithium manganese oxide electrodes. PMID:12824932

  17. Cycle life test of secondary spacecraft cells

    NASA Technical Reports Server (NTRS)

    Harkness, J. D.

    1980-01-01

    The results of the life cycling program on rechargeable calls are reported. Information on required data, the use of which the data will be put, application details, including orbital description, charge control methods, load rquirements, etc., are given. Cycle tests were performed on 660 sealed, nickel cadmium cells. The cells consisted of seven sample classifications ranging form 3.0 to 20 amp. hours. Nickel cadmium, silver cadmium, and silver zinc sealed cells, excluding synchronous orbit and accelerated test packs were added. The capacities of the nickel cadmium cells, the silver cadmium and the silver zinc cells differed in range of amp hrs. The cells were cylced under different load, charge control, and temperature conditions. All cell packs are recharged by use of a pack voltage limit. All charging is constant current until the voltage limit is reached.

  18. Stainless steel electrode characterizations by electrochemical impedance spectroscopy for dye-sensitized solar cells

    Microsoft Academic Search

    A.-F. Kanta; A. Decroly

    2011-01-01

    Electrochemical impedance spectroscopy (EIS) was used to understand the electrochemical mechanisms which appear in dye-sensitized solar cells (DSSCs). This qualitative and quantitative technique permits identification of the phenomena proceeding within the different elements composing the cell and at their interfaces.In this study, the classical conducting glass substrate was replaced by a protected stainless steel (304 type) substrate as the counter-electrode

  19. Solid electrolyte-electrode system for an electrochemical cell

    DOEpatents

    Tuller, Harry L. (Wellesley, MA); Kramer, Steve A. (Somerville, MA); Spears, Marlene A. (Woburn, MA)

    1995-01-01

    An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided.

  20. Solid electrolyte-electrode system for an electrochemical cell

    DOEpatents

    Tuller, H.L.; Kramer, S.A.; Spears, M.A.

    1995-04-04

    An electrochemical device including a solid electrolyte and solid electrode composed of materials having different chemical compositions and characterized by different electrical properties but having the same crystalline phase is provided. A method for fabricating an electrochemical device having a solid electrode and solid electrolyte characterized by the same crystalline phase is also provided. 17 figures.

  1. Electrochemical characteristics of LiFePO 4 \\/LiCoO 2 mixed electrode for Li secondary battery

    Microsoft Academic Search

    Hyun-Soo Kim; Mingzhe Kong; Ketack Kim; Ick-Jun Kim; Hal-Bon Gu

    2009-01-01

    LiFePO4 cathode active material was synthesized using a solid state method and a mixed cathode was prepared by adding LiCoO2. A coin cell was prepared using the mixed cathode and its electrochemical performances were evaluated. The LiFePO4 material improved both in thermal stability and rate capability. The discharge capacity of the 5 wt.% LiCoO2-added LiFePO4 material was 139.4 mAh\\/g at 0.2 C rate,

  2. Recovery and electrochemical performance in lithium secondary batteries of biochar derived from rice straw.

    PubMed

    Ryu, Da-Jeong; Oh, Rye-Gyeong; Seo, Yong-Deuk; Oh, Seok-Young; Ryu, Kwang-Sun

    2015-07-01

    Renewable biomass has attracted great attention for the production of biooil, biogas, and biochar, a carbon residual applicable for carbon sequestration and environmental remediation. Rice straw is one of the most common biomasses among agricultural wastes in South Korea. As part of our advanced and environmentally friendly research, we applied biochar derived from rice straw as the anode material for lithium-ion batteries (LIBs). Porous carbons with a high surface area were prepared from rice straw. Such porous carbons have exhibited particularly large reversible capacity and hence proven to be a candidate anode material for high-rate and high-capacity LIBs. Rice straw-derived biochars were synthesized at four different temperatures: 400, 550, 700, and 900 °C. The surface was modified by using HCl and H2O2 on the 550 °C biochar in order to increase the surface area. The resulting biochar was characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). The surface area was measured by Brunauer-Emmett-Teller (BET) method. The electrochemical characterizations were investigated by galvanostatic charge-discharge (CD) curves, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). All samples exhibited reversible capacities of below 200 mAh g(-1). The surface-modified biochars exhibited improved cycle performance. Surface modification using HCl showed better cycle performance than H2O2. However, the capacities of the treated 550 °C biochar were similar to those of non-surface-modified biochar. PMID:25821037

  3. Corrosion mechanism of cuprous oxide/iodide solar electrochemical cell

    NASA Astrophysics Data System (ADS)

    Tennakone, K.; Gurunnanselage, W.; Dharmaratne, D.; Jayewardena, S. C.

    1982-01-01

    Mechanisms for cuprous oxide corrosion in an iodide solution are investigated in light of the importance of instability effects arising from semiconductor electrode corrosion in solar electrochemical cells. Experiments involved the use of a potassium iodide solution containing a trace of iodine as the redox electrolyte, with a cuprous oxide-coated copper plate as the photocathode and a copper window coated with cupric sulphide as the counterelectrode. Measurement of the time dependence of the short circuit current at constant illumination intensity reveals it to undergo a rapid decay accompanied by the formation of a cuprous iodide-cupric oxide deposit on the photocathode surface. The region surrounding a circular patch of light focussed on the photocathode is found to exhibit CuO and CuI deposits signalling corrosion in the anodic region surrounding the cathodic spot. Measurements of the time dependence of the open circuit voltage furthermore indicate that the saturation voltage decays with time, due to short circuiting in the photocathode between anodic and cathodic regions.

  4. Electrochemical desorption of self-assembled monolayers and its applications in surface chemistry and cell biology

    Microsoft Academic Search

    Kang Sun; Bo Jiang; Xingyu Jiang

    2011-01-01

    Electrochemical desorption (ECD) of self-assembled monolayers (SAMs) is an important process that can dynamically modify surface properties. ECD of SAMs has found applications in biochemical assays and the precise control of cell adhesion. As cell adhesion is controlled by the chemistry of underlying substrate, ECD provides a means to achieve spatiotemporal control of cell behaviors by electrically addressing the substrate.

  5. Photocured Gelled Electrolytes For Secondary Li Cells

    NASA Technical Reports Server (NTRS)

    Nagasubramanian, Ganesan

    1994-01-01

    Class of photocured polymers exhibiting lithium-ion conductivities greater than those of well-studied polymers based on polyethylene oxide (PEO) show promise as polymeric electrolytes in rechargeable lithium cells. Increase in conductivity occasioned by use of electrolytes, coupled with amenability of electrolytes to formation into uniform thin (less than 25 micrometers thick), wide films, expected to result in cells with power densities greater than 100 W h/kg and charge/discharge rates exceeding currents equal, in amperes, to ampere-hour ratings. All-solid-state lithium batteries containing these electrolytes used as high-power, high-rate rechargeable power sources in commercial and aerospace applications.

  6. Electrochemical studies on niobium triselenide cathode material for lithium rechargeable cells

    Microsoft Academic Search

    B. V. Ratnakumar; C. L. Ni; S. DiStefano; G. Nagasubramanian; C. P. Bankston

    1989-01-01

    Niobium triselenide offers promise as a high energy density cathode material for ambient temperature lithium rechargeable cells. The electrochemical behavior of NbSeâ in the battery electrolyte, i.e., 1.5m LiAsFâ\\/2 Me-THF is reported here. A detailed study has been carried out using various ac and dc electrochemical techniques to establish the mechanism of intercalation of three equivalents of Li with NbSeâ

  7. Electrochemical photovoltaic cells. Quarterly technical progress report, August 1-October 31, 1980

    SciTech Connect

    Ang, P. G.P.; Sammells, A. F.

    1980-12-01

    Liquid-junction photoelectrochemical cells can be used either for the direct conversion of solar energy to electricity or to generate stored chemical species available for later electrochemical discharge. The objective of this program is to identify experimental approaches for electrochemical photovoltaic cells that not only show promise of high power-conversion efficiencies but also have the potential to achieve long life and the capacity for energy storage. The work is organized as follows: (1) selection of high-efficiency semiconductor photoelectrode/electrolyte systems; (2) development of long-life electrochemical photovoltaic cells; (3) development of an all solid-state electrochemical photovoltaic cell with in-situ storage; and (4) demonstration of laboratory-size photoelectrochemical cell with redox storage. This program is directed toward identifying a suitable match between the proposed semiconductor and the redox species present in aqueous, nonaqueous, and solid electrolytes for achieving the necessary performance and semiconductor stability requirements. Emphasis is on aqueous electrolyte-based systems where fast kinetics are favored. The proposed systems will be compatible with convenient storage of the electroactive species generated and their later electrochemical discharge in a redox cell.

  8. Microstructures and electrochemical properties of Si-xTiNi alloys for lithium secondary batteries.

    PubMed

    Kwon, Hye Jin; Song, Jong Jin; Ahn, Deuk Kyu; Hong, Soon Ho; Cho, Jong Soo; Moon, Jeong Tak; Sohn, Keun Yong; Park, Won-Wook

    2013-05-01

    The rapidly solidified Si-xTiNi (x = 0.2-0.45) alloy ribbons were fabricated via melt spinning process. The thickness of the melt-spun ribbons was about 12.5 microm, and the sound section was selected for the experiment. The microstructures of the ribbons were analyzed using XRD, FE-SEM, and HR-TEM: The primary silicon particles of 30 nm-100 n min diameter were finely dispersed in the inactive buffering matrix of Si7Ni4Ti4 phase. The charge/discharge energy capacity and electrochemical properties were significantly influenced by the relative ratio of NiTi to silicon. With increasing the total amount of Ni and Ti content up to 45 at%, the amount of Si7Ni4Ti4 phase increased and the cycle performance was improved. The Si7Ni4Ti4 phase acted as a buffer for the volume expansion/contraction of Si occurring during the alloying and dealloying, and it could prevent a significant deterioration in cycle performance of the battery. PMID:23858870

  9. Breast tumor cell detection at single cell resolution using an electrochemical impedance technique.

    PubMed

    Arya, Sunil K; Lee, Kok Chuan; Bin Dah'alan, Dhiya'uddin; Daniel; Rahman, Abdur Rub Abdur

    2012-07-01

    Gold micro-electrodes with various diameters (25, 50, 75, 100 and 250 ?m) were manufactured using standard micro-fabrication techniques and optimized for counting of MCF-7 cells (breast tumor cells) with single cell resolution. For specific cell capture, anti-EpCAM was immobilized on 11-mercaptoundecanoic acid (11-MUA)-3-mercaptopropionic acid (3-MPA) mixed self-assembled monolayer (SAM) modified gold surface of micro-electrodes. Electrodes were characterized using optical, cyclic voltammetry and electrochemical impedance spectroscopic (EIS) techniques. Cell capture response recorded using EIS suggested that optimum electrode dimensions should be analogous to desired cell size. For MCF-7 cells with an average diameter of 18 ± 2 ?m, an electrode with 25 ?m diameter was established as the optimum electrode size for precise single cell recognition and enumeration. In EIS investigation, the 25 ?m electrode exhibited an impedance change of ~2.2 × 10(7) ? in response to a single tumor cell captured on its surface. On the other hand other electrodes (250, 100, 75 and 50 ?m) showed much less response for a single tumor cell. In future, the use of high density arrays of such electrodes with surface modifications will result in miniaturized lab on a chip devices for precise counting of MCF-7 cells with single cell resolution. PMID:22513827

  10. Electrode for electrolyte circulation-type cell stack secondary battery

    Microsoft Academic Search

    H. Itoh; T. Hirose; A. Yamamoto

    1984-01-01

    An electrode for an electrolyte circulation-type cell stack secondary battery includes a pair of microchannels for supplying and exciting an electrolyte to or from an electrode member, and each of the microchannels is formed a first hindrance portion having a plurality of wall-shaped projections and a second hindrance portion integrally with a stepped portion in the electrode thickness direction and

  11. Non-Kinetic Losses Caused by Electrochemical Carbon Corrosion in PEM Fuel Cells

    SciTech Connect

    Park, Seh Kyu; Shao, Yuyan; Viswanathan, Vilayanur V.; Liu, Jun; Wang, Yong

    2012-05-01

    This paper presented non-kinetic losses in PEM fuel cells under an accelerated stress test of catalyst support. The cathode with carbon-supported Pt catalyst was prepared and characterized with potential hold at 1.2 V vs. SHE in PEM fuel cells. Irreversible losses caused by carbon corrosion were evaluated using a variety of electrochemical characterizations including cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectroscopy, and polarization technique. Ohmic losses at the cathode with potential hold were determined using its capacitive responses. Concentration losses in PEM fuel cells were analyzed in terms of Tafel behavior and thin film/flooded-agglomerate dynamics.

  12. Cell and current collector felt arrangement for solid oxide electrochemical cell combinations

    DOEpatents

    Reichner, Philip (Plum Boro, PA)

    1988-01-01

    A solid electrolyte electrochemical cell combination 1 is made, comprising an annular, axially elongated, inner electrode 2 containing at least one interior gas feed conduit 3; annular solid electrolyte segments 4 around and covering portions of the inner electrode; annular outer electrode segments 6 around and covering portions of the electrolyte segments; electronically conducting, non-porous, interconnection material 5 disposed between electrolyte segments and in contact with the inner electrode, and electronically conducting, porous, metal fiber current collector felts 7 disposed on top of the non-porous interconnect material and outer electrode segments, where both the non-porous interconnect material and the porous metal felts are disposed circumferentially about the cell, transversely to the axial length of the cell and the inner electrode is continuous for the entire axial length of the cell combination.

  13. Method and device for the detection of phenol and related compounds. [in an electrochemical cell

    NASA Technical Reports Server (NTRS)

    Schiller, J. G.; Liu, C. C. (inventors)

    1979-01-01

    A method is described which permits the selective oxidation and potentiometric detection of phenol and related compounds in an electrochemical cell. An anode coated with a gel immobilized oxidative enzyme and a cathode are each placed in an electrolyte solution. The potential of the cell is measured by a potentiometer connected to the electrodes.

  14. Electrochemical models for the discharge characteristics of the nickel cadmium cell

    NASA Technical Reports Server (NTRS)

    Spritzer, M. S.

    1981-01-01

    The potential time characteristics of a preconditioned fully charged cell discharge at constant current was studied. Electrochemical principles applied to the sealed nickel cadmium cell and its behavior and to predict operating characteristics were described. A thermodynamic approach to arrive at several related but different equations and its discharge are reported.

  15. Electrochemical Polishing of Silverware: A Demonstration of Voltaic and Galvanic Cells

    ERIC Educational Resources Information Center

    Ivey, Michelle M.; Smith, Eugene T.

    2008-01-01

    In this demonstration, the students use their knowledge of electrochemistry to determine that tarnish can be removed from silverware by electrochemically converting it back to silver using items commonly available in the kitchen: aluminum foil and baking soda. In addition to using this system as an example of a galvanic cell, an electrolytic cell

  16. 3D CFD ELECTROCHEMICAL AND HEAT TRANSFER MODEL OF AN INTERNALLY MANIFOLDED SOLID OXIDE ELECTROLYSIS CELL

    Microsoft Academic Search

    Grant L. Hawkes; James E. OBrien; Greg Tao

    2011-01-01

    A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created to model high-temperature electrolysis cell performance and steam electrolysis in an internally manifolded planar solid oxide electrolysis cell (SOEC) stack. This design is being evaluated at the Idaho National Laboratory for hydrogen production from nuclear power and process heat. Mass, momentum, energy, and species conservation and transport are provided

  17. Electrochemical properties of the NiS powder prepared by co-precipitation method for lithium secondary battery.

    PubMed

    Ryu, Ho-Suk; Ha, Chung-Wan; Ji, Seong-Yong; Ahn, In-Shup; Ahn, Jou-Hyeon; Ahn, Hyo-Jun; Kim, Ki-Won

    2014-10-01

    We synthesized two nickel sulfide powders by simple method. One is nickel sulfide powder (CNS) by co-precipitation is composed of nano-sized nickel sulfides as NiS and NIS2. The other is nickel sulfide powder (HNS) by heat-treatment of CNS is composed nano-sized NIS. The electrode using CNS has a high first discharge capacity of 600 mA h g(-1) at 0.5 C and the discharge capacity after 20th cycle is 312 mA h g(-1). The electrode using HNS has a high first discharge capacity of 551 mA h g(-1) at 0.5 C and has the discharge capacity of 412 mA h g(-1) after 50th. The discharge rate capability has over 92% at 1 C versus 0.2 C. The nano-sized nickel sulfides are synthesized by simple co-precipitation method has good electrochemical properties such as high first discharge capacity, good cycle life and good rate capability for lithium secondary battery. PMID:25942899

  18. Electrochemical decolorization of methyl orange powered by bioelectricity from single-chamber microbial fuel cells.

    PubMed

    Zhang, Baogang; Wang, Zhijun; Zhou, Xiang; Shi, Chunhong; Guo, Huaming; Feng, Chuanping

    2015-04-01

    Methyl orange (MO), a typical azo dye, is a well-known recalcitrant pollutant in dye wastewater. An aeration electrochemical system with single-chamber microbial fuel cell (MFC) as renewable power sources is proposed for MO decolorization. The enhanced color removal efficiency up to 90.4% within 360 min is observed with voltage across the aeration electrolytic reactor fixed at 700 mV. The results from gas chromatography-mass spectrometry (GC-MS) analysis indicate the destruction of MO, with generation of low molecular weight compounds such as benzene derivatives. Comparison experiments imply the indirect electrochemical oxidation of MO by generated H2O2 is mainly responsible for MO decolorization in present study. This work offers a cost-effective electrochemical method for enhancing electrochemical degradation of dyes with bioelectricity generated from MFCs. PMID:25661516

  19. Secondary sensory cells in the gravity receptor system of the statocyst of Octopus vulgaris

    Microsoft Academic Search

    Bernd-Ulrich Budelmann; Gesa Thies

    1977-01-01

    The presence of secondary sensory cells in the Octopus gravity receptor system has been demonstrated. In serial thin sections of the receptor cells (hair cells) no axons were found leaving the cells. Instead, synapses were observed with synaptic vesicles lying inside the receptor cells. Both data clearly indicate that the receptor hair cells represent secondary sensory cells. In addition, efferent

  20. Electrochemical hydrogen pump for recirculation of hydrogen in a fuel cell stack

    Microsoft Academic Search

    Frano Barbir; Haluk Görgün

    2007-01-01

    The objective of this work is to evaluate the use of an electrochemical hydrogen pump for recirculation of hydrogen in a fuel\\u000a cell stack. The hydrogen pump needed about 130 mV at 0.5 A cm?2, primarily because of the cell resistance (0.18 ? cm2). This voltage loss was higher than a fuel cell voltage gain resulting from hydrogen recirculation. However, if one pumping\\u000a cell is

  1. Overcharge and overdischarge protection of ambient temperature secondary lithium cells

    NASA Technical Reports Server (NTRS)

    Huang, Chen-Kuo (inventor); Surampudi, Subbarao (inventor); Attia, Alan I. (inventor); Halpert, Gerald (inventor)

    1994-01-01

    A cathode additive is provided for protecting an ambient temperature secondary lithium cell from overcharging or overdischarging. The cathode additive is chosen to create an upper voltage plateau which is slightly higher than a characteristic charge cutoff voltage of the cathode of the cell. The cathode additive additionally creates a lower voltage plateau which is slightly lower than the characteristic discharge cutoff voltage of the cell. Preferably, the cathode additive is a transition metal oxide or a sulfide and may, for example, include a mixture of Li2Mn2O4 and Li(0.1)MoO2.

  2. Performance characteristics of ambient temperature secondary lithium cells

    NASA Technical Reports Server (NTRS)

    Deligiannis, F.; Shen, D.; Subbarao, S.; Whitcanack, L.; Halpert, G.

    1988-01-01

    State of art ambient temperature secondary lithium cells were evaluated to determine their performance capability and limitations and to assess the present status of the technology of these cells. Li-MoS2, Li-NbSe3 and Li-TiS2 cells were evaluated for their charge/discharge characteristics, rate capability, and cycle life performance. The cells evaluated have a cycle life of 100-250 cycles at moderate discharge rates (C/5). The specific energy of these cells is between 50 and 100 Wh/Kg, depending upon the system. This paper describes the details of the cell designs, the test procedures, and the results of the evaluation studies.

  3. A novel LTCC electrochemical cell construction and characterization: a detection compartment for portable devices.

    PubMed

    Pesquero, Naira Canevarolo; Gongora-Rubio, Mário Ricardo; Yamanaka, Hideko

    2013-08-01

    In this work we described for the first time the construction of a 25 ?L electrochemical cell from low temperature co-fired ceramic (LTCC) material and carbon screen-printed electrode applicable in portable devices. Firstly, a carbon screen-printed electrode was prepared and characterized by cyclic voltammetry and scanning electron microscopy. Afterwards carbon polymeric film and metal pastes were dropped into the LTCC cell cavities in order to determine the device electrodes, and this arrangement was also electrochemically characterized. The great advantage of this promising device is the simple construction method and its widespread applicability in reusable portable devices. PMID:23748910

  4. Improved alkaline earth-oxyhalide electrochemical cell for low-temperature use

    SciTech Connect

    Binder, M.; Walker, C.W.

    1988-05-20

    This invention relates in general to an alkaline earth-oxyhalide electrochemical cell and in particular, to an improved alkaline earth oxyhalide electrochemical cell for low temperature use. A typical cell includes a calcium anode, 1M Ca(AlCl/sub 4/)/sub 2/ thionyl chloride/75% Shawinigan - 25% acetone washed Black Pearls 2000 carbon black cathode. The improvement to this cell involves the addition of 10 vol. % bromine to the electrolyte. During discharge at about -30 C, cathode potential is raised by about 0.5 volt providing a cell voltage well above the 2.0 volt minimum which is a standard military specification. Without bromine, cell capacity is about one minute. With the addition of bromine, load voltage is initially 2.5 volts, then slowly decreases to 2.0 volts over about twelve minutes.

  5. Paraneoplastic cutaneous lupus secondary to esophageal squamous cell carcinoma.

    PubMed

    Koritala, Thoyaja; Tworek, Joseph; Schapiro, Brian; Zolotarevsky, Eugene

    2015-06-01

    Sporadic subacute cutaneous lupus erythematosus (SCLE) in an elderly man does not fit a typical demographic for the disease process. Using the McLean's criteria we were able to establish a temporal relationship between the patient's diagnosis of esophageal squamous cell carcinoma (SCC) and his dermatosis, both of which responded to cytotoxic chemotherapy. The clinical presentation and progression of the clinical illness is supportive of a very unusual and not previously reported paraneoplastic SCLE secondary to esophageal SCC. PMID:26029469

  6. Porous silicon antireflection coating by electrochemical and chemical etching for silicon solar cell manufacturing

    Microsoft Academic Search

    M. Lipiski; S. Bastide; P. Panek; C. Lévy-Clément

    2003-01-01

    The formation of porous Si (PSi) antireflection coating (ARC) on n+-p multicrystalline Si solar cells has been investigated in view of its implementation at the last stage of the solar cell processing. PSi layers were formed either by electrochemical (EC) etching or by chemical stain (CS) etching and led to effective reflectivity around 13% (AM1.5). Solar cells with solar energy

  7. A zoom into the nanoscale texture of secondary cell walls

    PubMed Central

    2014-01-01

    Background Besides classical utilization of wood and paper, lignocellulosic biomass has become increasingly important with regard to biorefinery, biofuel production and novel biomaterials. For these new applications the macromolecular assembly of cell walls is of utmost importance and therefore further insights into the arrangement of the molecules on the nanolevel have to be gained. Cell wall recalcitrance against enzymatic degradation is one of the key issues, since an efficient degradation of lignocellulosic plant material is probably the most crucial step in plant conversion to energy. A limiting factor for in-depth analysis is that high resolution characterization techniques provide structural but hardly chemical information (e.g. Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM)), while chemical characterization leads to a disassembly of the cell wall components or does not reach the required nanoscale resolution (Fourier Tranform Infrared Spectroscopy (FT-IR), Raman Spectroscopy). Results Here we use for the first time Scanning Near-Field Optical Microscopy (SNOM in reflection mode) on secondary plant cell walls and reveal a segmented circumferential nanostructure. This pattern in the 100 nm range was found in the secondary cell walls of a softwood (spruce), a hardwood (beech) and a grass (bamboo) and is thus concluded to be consistent among various plant species. As the nanostructural pattern is not visible in classical AFM height and phase images it is proven that the contrast is not due to changes in surfaces topography, but due to differences in the molecular structure. Conclusions Comparative analysis of model substances of casted cellulose nanocrystals and spin coated lignin indicate, that the SNOM signal is clearly influenced by changes in lignin distribution or composition. Therefore and based on the known interaction of lignin and visible light (e.g. fluorescence and resonance effects), we assume the elucidated nanoscale structure to reflect variations in lignification within the secondary cell wall. PMID:24410854

  8. Development of a novel electrochemical sensor using pheochromocytoma cells and its assessment of acrylamide cytotoxicity.

    PubMed

    Sun, Xiulan; Ji, Jian; Jiang, Donglei; Li, Xiaowei; Zhang, Yinzhi; Li, Zaijun; Wu, Yongning

    2013-06-15

    We report on a sensitive, simple, label-free cell-based electrochemical sensor to monitor the toxic effect of acrylamide on the Pheochromocytoma cells. The surface of the electrode was modified with gold nanoparticles and electrochemically reduced graphene oxide. Cyclic voltammetry, impedance spectroscopy and differential pulse voltammetry were applied to characterize the modified electrode. Reduced graphene oxide was proved to increase electron-transfer rate between the cell and the surface of electrode, while gold nanoparticle retain cell bioactivity. The sensor exhibited good correlation to the logarithmic value of cell numbers ranging from 1.6×10(4) to 1.6×10(7) cells mL(-1), with R.S.D value of 1.68%. The value of differential pulse voltammetry (cell adsorption concentration of 1.6×10(7) cells mL(-1)) decreased with the concentration of acrylamide in range of 0.1-5 mM with the detection limit as 0.04 mM. Scanning electron microscope-based morphological and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide analysis confirmed the results of the electrochemical study. This sensor was proved to be a useful tool for probing the toxicity of cells, and assisted in the development of a labeling-free, simple, rapid and immediate detection method. PMID:23416312

  9. BMP7 Expression Correlates with Secondary Drug Resistance in Mantle Cell Lymphoma

    E-print Network

    Boyer, Edmond

    BMP7 Expression Correlates with Secondary Drug Resistance in Mantle Cell Lymphoma Valérie Camara to identify genes involved in secondary drug resistance in mantle cell lymphomas (MCL). Experimental Design in secondary resistance in mantle cell lymphoma. Citation: Camara-Clayette V, Koscielny S, Roux S, Lamy T, Bosq

  10. Cerium-modified doped strontium titanate compositions for solid oxide fuel cell anodes and electrodes for other electrochemical devices

    DOEpatents

    Marina, Olga A [Richland, WA; Stevenson, Jeffry W [Richland, WA

    2010-11-23

    The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells and electrochemical devices such as solid oxide fuel cells, electrolyzers, sensors, pumps and the like, the compositions comprising cerium-modified doped strontium titanate. The invention also provides novel methods for making and using anode material compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having anodes comprising the compositions.

  11. Thermo-electrochemical modeling of ammonia-fueled solid oxide fuel cells considering ammonia thermal decomposition in the anode

    Microsoft Academic Search

    Meng Ni

    2011-01-01

    Ammonia (NH3) is a promising hydrogen carrier and a possible fuel for use in Solid Oxide Fuel Cells (SOFCs). In this study, a 2D thermo-electrochemical model is developed to investigate the heat\\/mass transfer, chemical (ammonia thermal decomposition) and electrochemical reactions in a planar SOFC running on ammonia. The model integrates three sub-models: (1) an electrochemical model relating the current density–voltage

  12. High strength porous support tubes for high temperature solid electrolyte electrochemical cells

    DOEpatents

    Rossing, Barry R. (Churchill, PA); Zymboly, Gregory E. (Penn Hills, PA)

    1986-01-01

    A high temperature, solid electrolyte electrochemical cell is made, having an electrode and a solid electrolyte disposed on a porous, sintered support material containing thermally stabilized zirconia powder particles and from about 3 wt. % to about 45 wt. % of thermally stable oxide fibers.

  13. Electrochemical DeNO x in solid electrolyte cells—an overview

    Microsoft Academic Search

    K. Kammer

    2005-01-01

    The investigations in the field of electrochemical reduction of nitric oxide are reviewed. Using a cell based on an oxide ionic conductor it is shown that the selectivity and activity of the cathodes is strongly dependent on the temperature and of the composition of the cathode material. In general the selectivity is highest at the lowest temperatures. Cathode materials with

  14. Physical, mechanical and electrochemical characterization of all-perovskite intermediate temperature solid oxide fuel cells

    Microsoft Academic Search

    Alidad Mohammadi

    2008-01-01

    Strontium- and magnesium-doped lanthanum gallate (LSGM) has been considered as a promising electrolyte for solid oxide fuel cell (SOFC) systems in recent years due to its high ionic conductivity and chemical stability over a wide range of oxygen partial pressures and temperatures. This research describes synthesis, physical and mechanical behavior, electrochemical properties, phase evolution, and microstructure of components of an

  15. Free Energies of Formation Measurements on Solid-State Electrochemical Cells

    ERIC Educational Resources Information Center

    Rollino, J. A.; Aronson, S.

    1972-01-01

    A simple experiment is proposed that can provide the student with some insight into the chemical properties of solids. It also demonstrates the relationship between the Gibbs free energy of formation of an ionic solid and the emf of an electrochemical cell. (DF)

  16. A study on the impact of lithium-ion cell relaxation on electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Barai, Anup; Chouchelamane, Gael H.; Guo, Yue; McGordon, Andrew; Jennings, Paul

    2015-04-01

    Lithium-ion (Li-ion) batteries are of great interest to the automotive industry due to their higher power and energy density, higher cell voltage, longer cycle life and lower self-discharge compared to other battery chemistries. Electrochemical impedance spectroscopy is a powerful tool employed to investigate the fundamental electrochemical reactions within a Li-ion battery cell, which relates to state of charge, internal temperature and state of health. Its effectiveness has established it as a core method to study electrochemical behaviour of batteries in both off-line and on-line applications. In this work it is shown that in addition to state of charge, internal temperature and state of health, the time period between the removal of an electrical load and the impedance measurement affects the results. The study of five commercially available cells of varying capacities and electrode chemistries show that, regardless of cell type, maximum impedance change takes place within the first 4 h of the relaxation period. The root cause of this impedance change has been discussed from an electrochemical perspective.

  17. Electrochemical solar cells using CdSe thin film electrodes

    Microsoft Academic Search

    X.-R. Xiao; H. T. Tien

    1983-01-01

    Electrochemical photocells consisting of a CdSe thin film anode and a Pt cathode immersed in 1M Na2S-NaOH-S solution have been studied. CdSe thin films were formed on Ti, Cr, Mo, SnO2, glassy carbon, and graphite substrates by coating an aqueous mixture of CdSe, ZnCl2, and surfactant, subsequently sintering at 400-500 deg C in air. The current-voltage (I-V) relations, output power

  18. Method of bonding an interconnection layer on an electrode of an electrochemical cell

    DOEpatents

    Pal, U.B.; Isenberg, A.O.; Folser, G.R.

    1992-01-14

    An electrochemical cell containing an air electrode, contacting electrolyte and electronically conductive interconnection layer, and a fuel electrode, has the interconnection layer attached by: (A) applying a thin, closely packed, discrete layer of LaCrO[sub 3] particles, doped with an element selected from the group consisting of Ca, Sr, Co, Ba, Mg and their mixtures on a portion of the air electrode, and then (B) electrochemical vapor depositing a dense skeletal structure between and around the doped LaCrO[sub 3] particles. 2 figs.

  19. Method of bonding an interconnection layer on an electrode of an electrochemical cell

    DOEpatents

    Pal, Uday B. (Cambridge, MA); Isenberg, Arnold O. (Pittsburgh, PA); Folser, George R. (Lower Burrell, PA)

    1992-01-01

    An electrochemical cell containing an air electrode (16), contacting electrolyte and electronically conductive interconnection layer (26), and a fuel electrode, has the interconnection layer (26) attached by: (A) applying a thin, closely packed, discrete layer of LaCrO.sub.3 particles (30), doped with an element selected from the group consisting of Ca, Sr, Co, Ba, Mg and their mixtures on a portion of the air electrode, and then (B) electrochemical vapor depositing a dense skeletal structure (32) between and around the doped LaCrO.sub.3 particles (30).

  20. The effect of secondary impurities on solar cell performance

    NASA Technical Reports Server (NTRS)

    Hill, D. E.; Gutsche, H. W.; Wang, M. S.; Gupta, K. P.; Tucker, W. F.; Dowdy, J. D.; Crepin, R. J.

    1976-01-01

    Czochralski and float zone sigle crystals of silicon were doped with the primary impurities B or P so that a resistivity of 0.5 ohm cm resulted, and in addition doped with certain secondary impurities including Al, C, Cr, Cu, Fe, Mg, Mn, Na, Ni, O, Ti, V, and Zr. The actual presence of these impurities was confirmed by analysis of the crystals. Solar cell performance was evaluated and found to be degraded most significantly by Ti, V, and Zr and to some extent by most of the secondary impurities considered. These results are of significance to the low cost silicon program, since any such process would have to yield at least tolerable levels of these impurities.

  1. Electroendocytosis is driven by the binding of electrochemically produced protons to the cell's surface.

    PubMed

    Ben-Dov, Nadav; Rozman Grinberg, Inna; Korenstein, Rafi

    2012-01-01

    Electroendocytosis involves the exposure of cells to pulsed low electric field and is emerging as a complementary method to electroporation for the incorporation of macromolecules into cells. The present study explores the underlying mechanism of electroendocytosis and its dependence on electrochemical byproducts formed at the electrode interface. Cell suspensions were exposed to pulsed low electric field in a partitioned device where cells are spatially restricted relative to the electrodes. The cellular uptake of dextran-FITC was analyzed by flow cytometery and visualized by confocal microscopy. We first show that uptake occurs only in cells adjacent to the anode. The enhanced uptake near the anode is found to depend on electric current density rather than on electric field strength, in the range of 5 to 65 V/cm. Electrochemically produced oxidative species that impose intracellular oxidative stress, do not play any role in the stimulated uptake. An inverse dependence is found between electrically induced uptake and the solution's buffer capacity. Electroendocytosis can be mimicked by chemically acidifying the extracellular solution which promotes the enhanced uptake of dextran polymers and the uptake of plasmid DNA. Electrochemical production of protons at the anode interface is responsible for inducing uptake of macromolecules into cells exposed to a pulsed low electric field. Expanding the understanding of the mechanism involved in electric fields induced drug-delivery into cells, is expected to contribute to clinical therapy applications in the future. PMID:23209699

  2. Characterizing Ion Profiles in Dynamic Junction Light-Emitting Electrochemical Cells

    SciTech Connect

    Shoji, Tyko D.; Zhu, Zihua; Leger, Janelle M.

    2013-11-27

    Organic semiconductors have the unique ability to conduct both ionic and electronic charge carriers in thin films, an emerging advantage in applications such as light-emitting devices, transistors, and electrochromic devices, among others. Evidence suggests that the profiles of ions and electrochemical doping in the polymer film during operation significantly impact the performance and stability of the device. However, few studies have directly characterized ion profiles within LECs. Here, we present profiles of ion distributions in LECs following application of voltage, via time-of-flight secondary ion mass spectrometry. Ion distributions were characterized with regard to film thickness, salt concentration, applied voltage, and relaxation over time. Results provide insight into the correlation between ion profiles and device performance, as well as potential approaches to tuning electrochemical doping processes in LECs.

  3. Single cells and intracellular processes studied by a plasmonic-based electrochemical impedance microscopy

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Foley, Kyle; Shan, Xiaonan; Wang, Shaopeng; Eaton, Seron; Nagaraj, Vinay J.; Wiktor, Peter; Patel, Urmez; Tao, Nongjian

    2011-03-01

    Electrochemical impedance spectroscopy is a crucial tool for the detection and study of various biological substances, from DNA and proteins to viruses and bacteria. It does not require any labelling species, and methods based on it have been developed to study cellular processes (such as cell spreading, adhesion, invasion, toxicology and mobility). However, data have so far lacked spatial information, which is essential for investigating heterogeneous processes and imaging high-throughput microarrays. Here, we report an electrochemical impedance microscope based on surface plasmon resonance that resolves local impedance with submicrometre spatial resolution. We have used an electrochemical impedance microscope to monitor the dynamics of cellular processes (apoptosis and electroporation of individual cells) with millisecond time resolution. The high spatial and temporal resolution makes it possible to study individual cells, but also resolve subcellular structures and processes without labels, and with excellent detection sensitivity (~2 pS). We also describe a model that simulates cellular and electrochemical impedance microscope images based on local dielectric constant and conductivity.

  4. Electrochemical photovoltaic and photoelectrochemical storage cells based on II-VI polycrystalline thin film materials

    Microsoft Academic Search

    Wallace

    1983-01-01

    Research on electrochemical photovoltaic cells incorporating thin film CdSe and CdSe \\/SUB x\\/ Te \\/SUB 1-x\\/ photoanodes has progressed to the point where efficiencies of up to 7% can be achieved on small area electrodes using a polysulfide electrolyte. Higher efficiencies can be obtained in alternate electrolytes in significantly less stable systems. The major limitations on cell efficiency are associated

  5. Electrochemical photovoltaic and photoelectrochemical storage cells based on II-IV polycrystalline thin-film materials

    Microsoft Academic Search

    Wallace

    1983-01-01

    Research on electrochemical photovoltaic cells incorporating thin film CdSe and CdSe\\/sub x\\/Te\\/sub 1-x\\/ photoanodes has progressed to the point where efficiencies of up to 7% can be achieved on small area electrodes using a polysulfide electrolyte. Higher efficiencies can be obtained in alternate electrolytes in significantly less stable systems. The major limitations on cell efficiency are associated with the open

  6. Electrochemical polymerization of tetra-(4-hydroxyphenyl) porphyrin for organic solar cells

    NASA Astrophysics Data System (ADS)

    Veerender, P.; Koiry, S. P.; Saxena, Vibha; Jha, P.; Chauhan, A. K.; Aswal, D. K.; Gupta, S. K.

    2012-06-01

    Electrochemical oxidation of tetrakis-5,10,15,20-(4-hydroxyphenyl)porphyrin (THPP) on ITO electrodes was carried out. It leads to a uniform polymeric film (poly-THPP) with a nanostructured morphology. Poly-THPP electrodes as a bilayer organic solar cell and bulk heterojunction solar cells are investigated. The device with Phenyl-C61-butyric acid methyl ester (PCBM) integrated bilayer shows a modest photoactivity.

  7. Fluorescent magnetic bead-based mast cell biosensor for electrochemical detection of allergens in foodstuffs.

    PubMed

    Jiang, Donglei; Zhu, Pei; Jiang, Hui; Ji, Jian; Sun, Xiulan; Gu, Wenshu; Zhang, Genyi

    2015-08-15

    In this study, a novel electrochemical rat basophilic leukemia cell (RBL-2H3) cell sensor, based on fluorescent magnetic beads, has been developed for the detection and evaluation of different allergens in foodstuffs. Fluorescein isothiocyanate (FITC) was successfully fused inside the SiO2 layer of SiO2 shell-coated Fe3O4 nanoparticles, which was superior to the traditional Fe3O4@SiO2@FITC modification process. The as-synthesized fluorescent magnetic beads were then encapsulated with lipidosome to form cationic magnetic fluorescent nanoparticles (CMFNPs) for mast cell magnetofection. The CMFNPs were then characterized by SEM, TEM, VSM, FTIR, and XRD analyses, and transfected into RBL-2H3 cells through a highly efficient, lipid-mediated magnetofection procedure. Magnetic glassy carbon electrode (MGCE), which possesses excellent reproducibility and regeneration qualities, was then employed to adsorb the CMFNP-transfected RBL-2H3 cells activated by an allergen antigen for electrochemical assay. Results show that the exposure of model antigen-dinitrophenol-bovine serum albumin (DNP-BSA) to anti-DNP IgE-sensitized mast cells induced a robust and long-lasting electrochemical impedance signal in a dose-dependent manner. The detection limit was identified at 3.3×10(-4)ng/mL. To demonstrate the utility of this mast cell-based biosensor for detection of real allergens in foodstuffs, Anti-Pen a1 IgE and Anti-PV IgE-activated cells were employed to quantify both shrimp allergen tropomyosin (Pen a 1) and fish allergen parvalbumin (PV). Results show high detection accuracy for these targets, with a limit of 0.03?g/mL (shrimp Pen a 1) and 0.16ng/mL (fish PV), respectively. To this effect, we conclude the proposed method is a facile, highly sensitive, innovative electrochemical method for the evaluation of food allergens. PMID:25889258

  8. Paraneoplastic cutaneous lupus secondary to esophageal squamous cell carcinoma

    PubMed Central

    Tworek, Joseph; Schapiro, Brian; Zolotarevsky, Eugene

    2015-01-01

    Sporadic subacute cutaneous lupus erythematosus (SCLE) in an elderly man does not fit a typical demographic for the disease process. Using the McLean’s criteria we were able to establish a temporal relationship between the patient’s diagnosis of esophageal squamous cell carcinoma (SCC) and his dermatosis, both of which responded to cytotoxic chemotherapy. The clinical presentation and progression of the clinical illness is supportive of a very unusual and not previously reported paraneoplastic SCLE secondary to esophageal SCC. PMID:26029469

  9. Electrochemical Encyclopedia

    NSDL National Science Digital Library

    This site contains a compendium of 44 articles in electrochemistry. The articles cover a number of different topics including electrochemical capacitors, the electrochemistry of plant life, solid oxide fuel cells and electrolytic capacitors.

  10. Method of making an electrolyte for an electrochemical cell

    DOEpatents

    Bates, John B. (Oak Ridge, TN); Dudney, Nancy J. (Knoxville, TN)

    1996-01-01

    Described is a thin-film battery, especially a thin-film microbattery, and a method for making same having application as a backup or primary integrated power source for electronic devices. The battery includes a novel electrolyte which is electrochemically stable and does not react with the lithium anode and a novel vanadium oxide cathode Configured as a microbattery, the battery can be fabricated directly onto a semiconductor chip, onto the semiconductor die or onto any portion of the chip carrier. The battery can be fabricated to any specified size or shape to meet the requirements of a particular application. The battery is fabricated of solid state materials and is capable of operation between -15.degree. C. and 150.degree. C.

  11. Electrochemical solar cells using CdSe thin film electrodes

    NASA Astrophysics Data System (ADS)

    Xiao, X.-R.; Tien, H. T.

    1983-01-01

    Electrochemical photocells consisting of a CdSe thin film anode and a Pt cathode immersed in 1M Na2S-NaOH-S solution have been studied. CdSe thin films were formed on Ti, Cr, Mo, SnO2, glassy carbon, and graphite substrates by coating an aqueous mixture of CdSe, ZnCl2, and surfactant, subsequently sintering at 400-500 deg C in air. The current-voltage (I-V) relations, output power efficiency, open-circuit voltage, and short-circuit current were measured. 7% power conversion efficiency was obtained at 20 mW/square cm light intensity after photoetching. The monochromatic I-V curves were analyzed.

  12. Origin of photovoltage and photocurrent in the nanoporous dye-sensitized electrochemical solar cell

    SciTech Connect

    Schwarzburg, K.; Willig, F. [Hahn-Meitner-Institut, Berlin (Germany)

    1999-07-15

    The essential role of the dark equilibrium potential is discussed for charge separation and the photovoltaic functioning of the title cell. A quantitative model is presented for the potential distribution in the sponge-type title cell. The unique screening process for the photogenerated electrons is discussed that facilitates their extremely long lifetime since the screening ions cannot function as recombination centers. A general analogy is pointed out for the photovoltaic functioning of the sponge-type electrochemical solar cell and of a conventional single-crystal solid-state solar cell.

  13. Electrochemical characterization of sub-micro-gram amounts of organic semiconductors using scanning droplet cell microscopy.

    PubMed

    Gasiorowski, Jacek; Mardare, Andrei I; Sariciftci, Niyazi S; Hassel, Achim Walter

    2013-02-15

    Scanning droplet cell microscopy (SDCM) uses a very small electrolyte droplet at the tip of a capillary which comes in contact with the working electrode. This method is particularly interesting for studies on organic semiconductors since it provides localized electrochemical investigations with high reproducibility. One clear advantage of applying SDCM is represented by the very small amounts of material necessary (less than 1 mg). Organic materials can be investigated quickly and inexpensively in electrochemical studies with a high throughput. In the present study, thin layers of poly(3-hexylthiophene) (P3HT), which is one of the most often used material for organic solar cells, were deposited on ITO/glass as working electrodes in SDCM studies. The redox reactions in 0.1 M tetra(n-butyl)ammonium hexafluorophosphate (TBAPF6) dissolved in propylene carbonate were studied by cyclic voltammetry and by electrochemical impedance spectroscopy. Two reversible, distinct oxidation steps of the P3HT were detected and their kinetics were studied in detail. The doping of P3HT increased due to the electrochemical oxidation and had resulted in a decrease of the film resistance by a few orders of magnitude. Due to localization on the sample various parameter combinations can be studied quantitatively and reproducibly. PMID:24926226

  14. Electrochemical characterization of sub-micro-gram amounts of organic semiconductors using scanning droplet cell microscopy

    PubMed Central

    Gasiorowski, Jacek; Mardare, Andrei I.; Sariciftci, Niyazi S.; Hassel, Achim Walter

    2013-01-01

    Scanning droplet cell microscopy (SDCM) uses a very small electrolyte droplet at the tip of a capillary which comes in contact with the working electrode. This method is particularly interesting for studies on organic semiconductors since it provides localized electrochemical investigations with high reproducibility. One clear advantage of applying SDCM is represented by the very small amounts of material necessary (less than 1 mg). Organic materials can be investigated quickly and inexpensively in electrochemical studies with a high throughput. In the present study, thin layers of poly(3-hexylthiophene) (P3HT), which is one of the most often used material for organic solar cells, were deposited on ITO/glass as working electrodes in SDCM studies. The redox reactions in 0.1 M tetra(n-butyl)ammonium hexafluorophosphate (TBAPF6) dissolved in propylene carbonate were studied by cyclic voltammetry and by electrochemical impedance spectroscopy. Two reversible, distinct oxidation steps of the P3HT were detected and their kinetics were studied in detail. The doping of P3HT increased due to the electrochemical oxidation and had resulted in a decrease of the film resistance by a few orders of magnitude. Due to localization on the sample various parameter combinations can be studied quantitatively and reproducibly. PMID:24926226

  15. Exploratory cell research and fundamental processes study in solid state electrochemical cells

    SciTech Connect

    Smyrl, W.H.; Owens, B.B.; White, H.S. (Minnesota Univ., Minneapolis, MN (USA). Dept. of Chemical Engineering and Materials Science)

    1990-06-01

    Last year this program demonstrated that alternative to lithium had some merit on which to base new polymer electrolyte batteries and other electrochemical devices. We reported that Na, Zn, and Cu electrolytes have modest conductivities at 100{degree}C. Some preliminary cell cycling data were reported with V{sub 6}O{sub 13} insertion cathodes, and the successful cell cycling suggested that N{sup +}, Zn{sup +2} could be inserted and removed reversibly in the cathode material. Also, thin-film polymer cathodes were shown by impedance measurements to have three characteristic regions of behavior. Each region had different controlling processes with relaxation time constants that could be separated with careful manipulation of film thickness, morphology, and charging level. The present report gives results of the continuation of these studies. In particular, the sodium system was studied more intensively with conductivity measurements on sodium triflate in poly(ethyleneoxide)(PEO), and cell studies with V{sub 6}O{sub 13} and poly(pyrrole)(PPY) cathodes. The impedance work was concluded and several directions of new work in that area were identified. The insertion studies with single crystal V{sub 6}O{sub 13} were concluded on this program and transferred to NSF funding. 29 refs., 6 figs., 6 tabs.

  16. Exploratory cell research and fundamental processes study in solid state electrochemical cells

    NASA Astrophysics Data System (ADS)

    Smyrl, William H.; Owens, Boone B.; White, Henry S.

    1990-06-01

    Last year this program demonstrated that some alternatives to lithium had some merit on which to base new polymer electrolyte batteries and other electrochemical devices. We reported that Na, Zn, and Cu electrolytes have modest conductivities at 100 C. Some preliminary cell cycling data were reported with V6 O13 insertion cathodes, and the successful cell cycling suggested that N(sup +), Zn(sup +2) could be inserted and removed reversibly in the cathode material. Also, thin-film polymer cathodes were shown by impedance measurements to have three characteristic regions of behavior. Each region had different controlling processes with relaxation time constants that could be separated with careful manipulation of film thickness, morphology, and charging level. The present report gives results of the continuation of these studies. In particular, the sodium system was studied more intensively with conductivity measurements on sodium triflate in poly(ethyleneoxide)(PEO), and cell studies with V6 O13 and poly(pyrrole)(PPY) cathodes. The impedance work was concluded and several directions of new work in that area were identified. The insertion studies with single crystal V6 O13 were concluded on this program.

  17. Response of microfluidic fuel cells to secondary flows

    NASA Astrophysics Data System (ADS)

    Rossi, Massimiliano; Kähler, Christian J.

    2013-11-01

    Microfluidic or membraneless fuel cells (MFCs) are a recent class of miniaturized fuel cells (Ferrigno et al. 2002, Choban et al. 2004) composed by a microchannel in which a parallel laminar stream of two fluids, a fuel and an oxidant, is established. The fuel and oxidant remain in contact but do not mix due to the absence of turbulence. The simple architecture and the fact that no expensive proton exchange membranes are needed make this configuration technologically very attractive, however the efficiency especially in terms of fuel utilization is still too low to be competitive for practical applications. One limitation is given by the formation of depletion boundary layers at the electrodes that worsen the red-ox reactions. A way to reduce this problem is to use transversal secondary flows to stir the fluid streams and replenish the depletion layers. In this study, we intend to characterize the performance of MFC with curved channels in which the transversal secondary flows are present in the form of two counter-rotating vortices known as Dean vortices. The characterization will be completed by simultaneous measurements of the current intensity and of the flow velocity performed with 3D Astigmatic Particle Tracking Velocimetry.

  18. Electrochemical Performance and Stability of the Cathode for Solid Oxide Fuel Cells: III. Role of volatile boron species on LSM/YSZ and LSCF

    SciTech Connect

    Zhou, Xiao Dong; Templeton, Jared W.; Zhu, Zihua; Chou, Y. S.; Maupin, Gary D.; Lu, Zigui; Brow, R. K.; Stevenson, Jeffry W.

    2010-09-02

    Boron oxide is a key component to tailor the softening temperature and viscosity of the sealing glass for solid oxide fuel cells. The primary concern regarding the use of boron containing sealing glasses is the volatility of boron species, which possibly results in cathode degradation. In this paper, we report the role of volatile boron species on the electrochemical performance of LSM/YSZ and LSCF cathodes at various SOFC operation temperatures. The transport rate of boron, ~ 3.24×10-12 g/cm2•sec was measured at 750°C with air saturated with 2.8% moisture. A reduction in power density was observed in cells with LSM/YSZ cathodes after introduction of the boron source to the cathode air stream. Partial recovery of the power density was observed after the boron source was removed. Results from post-test secondary ion mass spectroscopy (SIMS) analysis the partial recovery in power density correlated with partil removal of the deposited boron by the clean air stream. The presence of boron was also observed in LSCF cathodes by SIMS analysis, however the effect of boron on the electrochemical performance of LSCF cathode was negligible. Coverage of triple phase boundaries in LSM/YSZ was postulated as the cause for the observed reduction in electrochemical performance.

  19. Continuous electrochemical monitoring of nitric oxide production in murine macrophage cell line RAW 264.7.

    PubMed

    Pekarova, Michaela; Kralova, Jana; Kubala, Lukas; Ciz, Milan; Lojek, Antonin; Gregor, Cenek; Hrbac, Jan

    2009-07-01

    In this study, we realized the continual and long-term electrochemical detection of NO production by stimulated macrophages using modified porphyrinic microsensor. The NO release from RAW 264.7 cells stimulated by lipopolysaccharide started 5 h after the lipopolysaccharide administration. After reaching its maximum at the sixth hour, the stable level of NO production was observed between the seventh and 12th hour of the experiment. This phase was followed by a gradual decline in NO production. A close correlation between the NO signal detected with microelectrode and nitrite accumulation, which had been determined in supernatants removed from stimulated cells, was observed. This finding was utilized for the calibration of the electrochemical experiment. The presence of iNOS enzyme, which constitutes a main requirement for NO production by stimulated macrophages, was confirmed by Western blot analysis of iNOS protein expression at key time points of the corresponding electrochemical experiment. The capability of our microsensor to instantaneously monitor the changes in the NO production by stimulated RAW 264.7 cells was demonstrated by the immediate decrease in the signal due to NO as a response to the addition of iNOS inhibitor into the cell culture medium. PMID:19430767

  20. Analysis of palladium-based anode electrode using electrochemical impedance spectra in direct formic acid fuel cells

    Microsoft Academic Search

    Won Suk Jung; Jonghee Han; S. Ha

    2007-01-01

    In this study, we used the electrochemical impedance spectra to evaluate the anode performance of direct formic acid fuel cell (DFAFC), and how its anode charge transfer resistance (Ranode,ct) and electrolyte resistance (Rele) are affected by various cell operating parameters. The parameters investigated in this study include the anode overpotentials, cell operation times, formic acid feed concentrations and cell temperatures.

  1. System and method for charging electrochemical cells in series

    DOEpatents

    DeLuca, William H. (Naperville, IL); Hornstra, Jr, Fred (St. Charles, IL); Gelb, George H. (Rancho Palos Verdes, CA); Berman, Baruch (Rancho Palos Verdes, CA); Moede, Larry W. (Manhattan Beach, CA)

    1980-01-01

    A battery charging system capable of equalizing the charge of each individual cell at a selected full charge voltage includes means for regulating charger current to first increase current at a constant rate until a bulk charging level is achieved or until any cell reaches a safe reference voltage. A system controller then begins to decrease the charging rate as long as any cell exceeds the reference voltage until an equalization current level is reached. At this point, the system controller activates a plurality of shunt modules to permit shunting of current around any cell having a voltage exceeding the reference voltage. Leads extending between the battery of cells and shunt modules are time shared to permit alternate shunting of current and voltage monitoring without the voltage drop caused by the shunt current. After each cell has at one time exceeded the reference voltage, the charging current is terminated.

  2. Sustainable energy: a review of formic acid electrochemical fuel cells

    Microsoft Academic Search

    Neil V. Rees; Richard G. Compton

    Of the many candidate fuels for low-temperature fuel cells, one of the most promising is formic acid. Although it has been\\u000a investigated as such for nearly 50 years, rapid advances in recent times have begun to release the potential for formic acid\\u000a fuel cells as high-performance, portable fuel cells with some products about to reach the market. In this review, we

  3. Carbon nanofiber and PEDOT-PSS bilayer systems as electrodes for symmetric and asymmetric electrochemical capacitor cells

    Microsoft Academic Search

    Ana Karina Cuentas Gallegos; Marina E. Rincón

    2006-01-01

    In this work, we describe the fabrication of electrodes based on carbon nanofibers (NFC), bilayer systems of NFC and a commercial polythiophene (PEDOT-PSS), and NFC\\/PEDOT-PSS composites, for symmetric and asymmetric electrochemical capacitor (EC) cells. The basic electrochemical characterization was carried out for each electrode material by cyclic voltammetry (CV) using a three-electrode cell and a non-aqueous electrolyte (1M LiClO4 in

  4. Carbon dioxide concentration for manned spacecraft using a molten carbonate electrochemical cell

    SciTech Connect

    Winnick, J.; Toghiani, H.; Quattrone, P.D.

    1982-01-01

    A high-temperature molten carbonate electrochemical cell has been tested for use as a carbon dioxide concentrator in a manned spacecraft. Carbon dioxide is removed from a stream of cabin air supplied to the cathode of the bench scale cell. It is then concentrated through the molten carbonate electrolyte to the anode. The anode is fed either hydrogen (energy producer) or nitrogen (substance producer). Performance variation with gas flow rate, cell temperature, carbon dioxide partial pressure, and current are presented and analyzed. 18 refs.

  5. The electrochemical performance of thin-electrolyte solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Zurawski, D.; Kueper, T.

    1993-04-01

    Several benefits are realized by lowering the operating temperature of solid oxide fuel cells (SOFC's) from 1000C to temperatures in the 600 to 800C range. Among the advantages are decreased reaction between fuel cell components, shorter startup times, and the possibility of using metals in stack construction; however, the achievable power density in conventional SOFC's is too low. A strategy for overcoming this limitation is to decrease the thickness of this layer by approximately an order of magnitude. Thin (5 micron electrolyte SOFC's have recently been fabricated by Allied-Signal Aerospace Systems and Equipment Company (ASASE). The electrochemical performance of these cells has been studied and is discussed.

  6. Voltammetric Scanning Electrochemical Cell Microscopy: Dynamic Imaging of Hydrazine Electro-oxidation on Platinum Electrodes.

    PubMed

    Chen, Chang-Hui; Jacobse, Leon; McKelvey, Kim; Lai, Stanley C S; Koper, Marc T M; Unwin, Patrick R

    2015-06-01

    Voltammetric scanning electrochemical cell microscopy (SECCM) incorporates cyclic voltammetry measurements in the SECCM imaging protocol, by recording electrochemical currents in a wide potential window at each pixel in a map. This provides much more information compared to traditional fixed potential imaging. Data can be represented as movies (hundreds of frames) of current (over a surface region) at a series of potentials and are highly revealing of subtle variations in electrode activity. Furthermore, by combining SECCM data with other forms of microscopy, e.g. scanning electron microscopy and electron backscatter diffraction data, it is possible to directly relate the current-voltage characteristics to spatial position and surface structure. In this work we use a "hopping mode", where the SECCM pipet probe is translated toward the surface at a series of positions until meniscus contact. Small amounts of residue left on the surface, upon probe retraction, demark the precise area of each measurement. We use these techniques to study hydrazine oxidation on a polycrystalline platinum substrate both in air and in a deaerated environment. In both cases, the detected faradaic current shows a structural dependence on the surface crystallographic orientation. Significantly, in the presence of oxygen (aerated solution) the electrochemical current decreases strongly for almost all grains (crystallographic orientations). The results highlight the flexibility of voltammetric SECCM for electrochemical imaging and present important implications for hydrazine electroanalysis. PMID:25942527

  7. Evolution of absorption spectra of C60 film in solid electrolyte cell during electrochemical reduction

    Microsoft Academic Search

    K. Kaneto; T. Abe; W. Takashima

    1995-01-01

    Absorption spectra of C60 film reduced electrochemically in a cell composed of solid polymer electrolyte and LiClO4 are studied. The results are compared with data of C60 anion solutions and films doped with alkali metals by vapor phase. Little difference is found in absorption spectra between the solutions and films of reduced C60 up to di-anion at least. This fact

  8. Electrochemical testing of suspension plasma sprayed solid oxide fuel cell electrolytes

    Microsoft Academic Search

    D. Waldbillig; O. Kesler

    2011-01-01

    Electrochemical performance of metal-supported plasma sprayed (PS) solid oxide fuel cells (SOFCs) was tested for three nominal electrolyte thicknesses and three electrolyte fabrication conditions to determine the effects of electrolyte thickness and microstructure on open circuit voltage (OCV) and series resistance (Rs). The measured OCV values were approximately 90% of the Nernst voltages, and electrolyte area specific resistances below 0.1?cm2

  9. Electrochemical modeling of ammonia-fed solid oxide fuel cells based on proton conducting electrolyte

    Microsoft Academic Search

    Meng Ni; Dennis Y. C. Leung; Michael K. H. Leung

    2008-01-01

    An electrochemical model was developed to study the NH3-fed and H2-fed solid oxide fuel cells based on proton conducting electrolyte (SOFC-H). The modeling results were consistent with experimental data in literature. It is found that there is little difference in working voltage and power density between the NH3-fed and the H2-fed SOFC-H with an electrolyte-support configuration due to an extremely

  10. Electrochemical oxidation of boron containing compounds on titanium carbide and its implications to direct fuel cells

    Microsoft Academic Search

    Vankayala Kiran; Suresh Babu Kalidindi; Balaji Rao Jagirdar; Srinivasan Sampath

    Electrochemical oxidation of sodium borohydride (NaBH4) and ammonia borane (NH3BH3) (AB) have been studied on titanium carbide electrode. The oxidation is followed by using cyclic voltammetry, chronoamperometry and polarization measurements. A fuel cell with TiC as anode and 40wt% Pt\\/C as cathode is constructed and the polarization behaviour is studied with NaBH4 as anodic fuel and hydrogen peroxide as catholyte.

  11. Surface effects and electrochemical cell capacitance in desorption electrospray ionization.

    PubMed

    Volný, Michael; Venter, Andre; Smith, Scott A; Pazzi, Marco; Cooks, R Graham

    2008-04-01

    Time resolved measurements show that during a desorption electrospray ionization (DESI) experiment, the current initially rises sharply, followed by an exponential decrease to a relatively steady current. When the high voltage on the spray emitter is switched off, the current drops to negative values, suggesting that the direction of current flow in the equivalent DESI circuit is reversed. These data demonstrate that the DESI source behaves as a dc capacitor and that the addition of a surface between the sprayer and the counter electrode in DESI introduces a new electrically active element into the system. The charging and discharging behavior was observed using different surfaces and it could be seen both by making current measurements on a plate at the entrance to the mass spectrometer as well as by measuring ion current in the linear ion trap within the vacuum system of the mass spectrometer. The magnitude of the steady state current obtained without analyte present on the surface is different for different surface materials, and different capacitor time constants of the equivalent RC circuits were calculated for different DESI surfaces. The PTFE surface has by far the greatest time constant and is also able to produce the highest DESI currents. Surface properties play a crucial role in charge transfer during DESI in addition to the effects of the chemical properties of the analyte. It is suggested that surface energy (wettability) is an important factor controlling droplet behavior on the surface. The experimental data are correlated with critical surface tension values of different materials. It is proposed, based on the results presented, that super-hydrophobic materials with extremely high contact angles have the potential to be excellent DESI substrates. It is also demonstrated, using the example of the neurotransmitter dopamine, that the surface charge that develops during a DESI-MS experiment can cause electrochemical oxidation of the analyte. PMID:18365123

  12. Mechanisms for shaping, orienting, positioning and patterning plant secondary cell walls

    PubMed Central

    Korolev, Andrey V; Calder, Grant; Lloyd, Clive W

    2011-01-01

    Xylem vessels are cells that develop a specifically ornamented secondary cell wall to ensure their vascular function, conferring both structural strength and impermeability. Further plasticity is given to these vascular cells by a range of different patterns described by their secondary cell walls that—as for the growth of all plant organs—are developmentally regulated. Microtubules and their associated proteins, named MAPs, are essential to define the shape, the orientation, the position and the overall pattern of these secondary cell walls. Key actors in this process are the land-plant specific MAP70 proteins which not only allow the secondary cell wall to be positioned at the cell cortex but also determine the overall pattern described by xylem vessel secondary cell walls. PMID:21558816

  13. Numerical Study of the Buoyancy-Driven Flow in a Four-Electrode Rectangular Electrochemical Cell

    NASA Astrophysics Data System (ADS)

    Sun, Zhanyu; Agafonov, Vadim; Rice, Catherine; Bindler, Jacob

    2009-11-01

    Two-dimensional numerical simulation is done on the buoyancy-driven flow in a four-electrode rectangular electrochemical cell. Two kinds of electrode layouts, the anode-cathode-cathode-anode (ACCA) and the cathode-anode-anode-cathode (CAAC) layouts, are studied. In the ACCA layout, the two anodes are placed close to the channel outlets while the two cathodes are located between the two anodes. The CAAC layout can be converted from the ACCA layout by applying higher electric potential on the two middle electrodes. Density gradient was generated by the electrodic reaction I3^-+2e^- =3I^-. When the electrochemical cell is accelerated axially, buoyancy-driven flow occurs. In our model, electro-neutrality is assumed except at the electrodes. The Navier-Stokes equations with the Boussinesq approximation and the Nernst-Planck equations are employed to model the momentum and mass transports, respectively. It is found that under a given axial acceleration, the electrolyte density between the two middle electrodes determines the bulk flow through the electrochemical cell. The cathodic current difference is found to be able to measure the applied acceleration. Other important electro-hydrodynamic characteristics are also discussed.

  14. Potassium Beta-Alumina/Molybdenum/Potassium Electrochemical Cells

    NASA Technical Reports Server (NTRS)

    Williams, R.; Kisor, A.; Ryan, M.; Nakamura, B.; Kikert, S.; O'Connor, D.

    1994-01-01

    potassium alkali metal thermal-to-electric converter (K-AMTEC) cells utilizing potassium beta alumina solid electrolyte (K-BASE) are predicted to have improved properties for thermal to electric conversion at somewhat lower temperatures than sodium AMTEC's.

  15. Electrochemical impedance spectroscopy of lithium-titanium disulfide rechargeable cells

    NASA Technical Reports Server (NTRS)

    Narayanan, S. R.; Shen, D. H.; Surampudi, S.; Attia, A. I.; Halpert, G.

    1993-01-01

    The two-terminal alternating current impedance of Li/TiS2 rechargeable cells was studied as a function of frequency, state-of-charge, and extended cycling. Analysis based on a plausible equivalent circuit model for the Li/TiS2 cell leads to evaluation of kinetic parameters for the various physicochemical processes occurring at the electrode/electrolyte interfaces. To investigate the causes of cell degradation during extended cycling, the parameters evaluated for cells cycled 5 times were compared with the parameters of cells cycled over 600 times. The findings are that the combined ohmic resistance of the electrolyte and electrodes suffers a tenfold increase after extended cycling, while the charge-transfer resistance and diffusional impedance at the TiS2/electrolyte interface are not significantIy affected. The results reflect the morphological change and increase in area of the anode due to cycling. The study also shows that overdischarge of a cathode-limited cell causes a decrease in the diffusion coefficient of the lithium ion in the cathode.

  16. Space Electrochemical Research and Technology

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This document contains the proceedings of NASA's fourth Space Electrochemical Research and Technology (SERT) Conference, held at the NASA Lewis Research Center on April 14-15, 1993. The objective of the conference was to assess the present status and general thrust of research and development in those areas of electrochemical technology required to enable NASA missions into the next century. The conference provided a forum for the exchange of ideas and opinions of those actively involved in the field, in order to define new opportunities for the application of electrochemical processes in future NASA missions. Papers were presented in three technical areas: advanced secondary batteries, fuel cells, and advanced concepts for space power. This document contains the papers presented.

  17. The stromal and haematopoietic antigen-presenting cells that reside in secondary lymphoid organs

    Microsoft Academic Search

    Anne L. Fletcher; Kutlu G. Elpek; Shannon J. Turley

    2010-01-01

    T cells encounter their cognate antigens in specialized compartments of secondary lymphoid organs (SLOs). There, dendritic cells (DCs) present self and non-self antigens to T cells, and promote immunity or tolerance depending on the availability of danger signals. Resident stromal cells orchestrate the interaction between T cells and DCs by recruiting them to T cell zones and guiding their migration

  18. Electrochemical and surface science research on fuel cells

    NASA Astrophysics Data System (ADS)

    Srinivasan, S.; Gonzalez, E. R.; Hsueh, K. L.; Chin, D. T.; Hyde, P. J.; Maggiore, C. J.; Gottesfeld, S.; Chang, H. R.; Derouin, C. R.; Bobbett, R. E.

    1984-06-01

    The development of advanced acid electrolyte fuel cells for power generation and transportation application is investigated. The ions CF3SO3(-) and H2PO4(-) have similar adsorption characteristics on mercury from dilute aqueous electrolytes ( 1 M). Transport properties in phosphoric acid show strong temperature and concentration dependences. Solvent clusters account for transport of 6 to 9 moles of water per mole of proton through Nafion membranes. Exchange current densities for oxygen reduction on platinum are dependent on anion adsorption from the electrolyte. The nuclear microprobe technique reveal: (1) the three-dimensional distribution of platinum in a fuel cell electrode, and (2) the loss of vanadium from a Pt-V electrocatalyst during fuel cell operation. The ellipsometric method was developed to measure anion adsorption on platinum. Single cells were assembled and tested for the proposed simulated drive-cycle-performance evaluations. An energy balance was made for a 20 kW phosphoric acid fuel cell power plant for a GM X-car.

  19. Process for manufacturing a lithium alloy electrochemical cell

    DOEpatents

    Bennett, William R. (North Olmstead, OH)

    1992-10-13

    A process for manufacturing a lithium alloy, metal sulfide cell tape casts slurried alloy powders in an organic solvent containing a dissolved thermoplastic organic binder onto casting surfaces. The organic solvent is then evaporated to produce a flexible tape removable adhering to the casting surface. The tape is densified to increase its green strength and then peeled from the casting surface. The tape is laminated with a separator containing a lithium salt electrolyte and a metal sulfide electrode to form a green cell. The binder is evaporated from the green cell at a temperature lower than the melting temperature of the lithium salt electrolyte. Lithium alloy, metal sulfide and separator powders may be tape cast.

  20. Degradation of microcystins by an electrochemical oxidative electrode cell.

    PubMed

    Gao, Yu; Shimizu, Kazuya; Utsumi, Motoo; Xue, Qiang; Feng, Chuanping; Sakharkar, Meena Kishore; Sugiura, Norio

    2013-01-01

    Microcystins (MCs), which are produced by cyanobacteria, are one of the most serious problems that threaten quality of drinking water and public health. In this study, an electrolysis cell with no electrolyte is demonstrated to degrade MCs (MC-RR, MC-YR and MC-LR) in both high and low concentrations. In addition, degradation of MCs was studied under different current densities. The results revealed that the electrolysis cell could degrade MCs successfully. It was observed that degradation of a single MC was faster than mixed types and statistical analysis revealed that the degradation rate of all the three MCs did not show much difference in mixed degradation. Analysis of hydroxyl radical concentration suggested a possible role of the hydroxyl radical in degradation of MCs. We propose that the electrolysis cell could be a promising treatment for effective removal of MCs in situ, especially in water purification plants where low amounts of salts (electrolytes) are present. PMID:23837354

  1. Direct In Vivo Electrochemical Detection of Haemoglobin in Red Blood Cells

    NASA Astrophysics Data System (ADS)

    Toh, Rou Jun; Peng, Weng Kung; Han, Jongyoon; Pumera, Martin

    2014-08-01

    The electrochemical behavior of iron ion in haemoglobin provides insight to the chemical activity in the red blood cell which is important in the field of hematology. Herein, the detection of haemoglobin in human red blood cells on glassy carbon electrode (GC) was demonstrated. Red blood cells or raw blood cells was immobilized on a glassy carbon electrode surface with Nafion films employed to sandwich the layer of biological sample firmly on the electrode surface. Cyclic voltammetry (CV) analyses revealed a well-defined reduction peak for haemoglobin at about -0.30 V (vs. Ag/AgCl) at the red blood cell (GC-Nf-RBC-3Nf) and blood (GC-Nf-B-3Nf) film modified GCE in a pH 3.5 phosphate buffer solution. We further demonstrated that the complex biological conditions of a human red blood cell displayed no interference with the detection of haemoglobin. Such findings shall have an implication on the possibilities of studying the electrochemical behaviour of haemoglobin directly from human blood, for various scientific and clinical purposes.

  2. Thin-film electrochemical power cells. Final report

    SciTech Connect

    Owens, B.B.; Smyrl, W.H.

    1991-01-01

    Fundamental properties of research cells were correlated with the projected performance of full scale power sources, considering both battery and supercapacitor concepts. In addition to establishing the data base for modelling and performance projections, the program had the additional objective of identifying loss mechanisms and degradation reactions, especially those unique to polymer thin film cell designs. Because of the intrinsic high electrode/electrolyte interface areas, interfacial reactions must be understood. Many applications require power under extreme conditions, and low temperature performance needs to be improved.

  3. Evaluation of ceramic insulators for lithium electrochemical reduction cells

    SciTech Connect

    Lauf, R.J.; DeVan, J.H. (Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.)

    1992-08-01

    This paper reports on screening tests which were conducted on 25 ceramics to evaluate their suitability as insulators in a Downs-type lithium electroreduction cell. Each material was exposed to molten lithium at 400[degrees]C for 100 h. Of the materials tested, beryllia, magnesia, yttria, yttrium aluminum garnet, and aluminum nitride were found to have acceptable compatibility with lithium. It is reasonable to expect that they are also compatible with molten LiCl-KCl electrolyte. These candidate materials can therefore be selected for various cell components based on fabricability or other considerations.

  4. Electrochemical study of multi-electrode microbial fuel cells under fed-batch and continuous flow conditions

    E-print Network

    Electrochemical study of multi-electrode microbial fuel cells under fed-batch and continuous flow November 2013 Available online 18 December 2013 Keywords: Multi-electrode Microbial fuel cells Hydraulic connected microbial fuel cells (MFCs) was compared with the reactors operated using individual electrical

  5. Electrochemical studies on niobium triselenide cathode material for lithium rechargeable cells

    SciTech Connect

    Ratnakumar, B.V.; Ni, C.L.; DiStefano, S.; Nagasubramanian, G.; Bankston, C.P.

    1989-01-01

    Niobium triselenide offers promise as a high energy density cathode material for ambient temperature lithium rechargeable cells. The electrochemical behavior of NbSe/sub 3/ in the battery electrolyte, i.e., 1.5m LiAsF/sub 6//2 Me-THF is reported here. A detailed study has been carried out using various ac and dc electrochemical techniques to establish the mechanism of intercalation of three equivalents of Li with NbSe/sub 3/ as well as the rate governing processes in the reduction of NbSe/sub 3/. Based on the experimental data, an equivalent circuit has been formulated to represent the NbSe/sub 3/-solution interface. The kinetic parameters for the reduction of NbSe/sub 3/ were evaluated from the ac and dc measurements. Finally, the structural change in NbSe/sub 3/ on lithiation during initial discharge which results in higher cell voltages and different electrochemical response as compared to virgin NbSe/sub 3/ was identified to be a loss of crystallographic order, i.e., amorphous by x-ray diffraction.

  6. Electrochemical Performance and Microbial Characterization of Thermophilic Microbial Fuel Cells

    Microsoft Academic Search

    K. C. Wrighton; P. Agbo; E. L. Brodie; K. A. Weber; T. Z. Desantis; G. L. Anderson; J. D. Coates

    2007-01-01

    Significant research effort is currently focused on microbial fuel cells (MFC) as a source of renewable energy. To date, most of these efforts have concentrated on MFCs operating at mesophilic temperatures. However, many previous studies have reported on the superiority of thermophilic conditions in anaerobic digestion and demonstrated a net gain in energy yield, in terms of methane, relative to

  7. Biclonal light chain gammopathy with aberrant CD33 expression in secondary plasma cell leukemia

    PubMed Central

    Gentry, Michael; Pettenati, Mark; Pang, Changlee S

    2013-01-01

    Plasma cell leukemia is a rare neoplastic proliferation of circulating plasma cells. Clonal proliferations of plasma cells, such as in plasma cell leukemia or plasma cell myeloma, are typically characterized by production of a monoclonal heavy and/or light chain immunoglobulin. We present a case of a secondary plasma cell leukemia arising from plasma cell myeloma with dual expression of lambda and kappa light chains along with aberrant expression of CD33, CD20, and dim CD56. This case emphasizes the importance of recognizing aberrant immunophenotypes in plasma cell leukemias and represents the first reported case of biclonal light chain expression in a secondary plasma cell leukemia. PMID:24133602

  8. Electrochemical cell apparatus having an integrated reformer-mixer nozzle-mixer diffuser

    DOEpatents

    Shockling, L.A.

    1991-09-10

    An electrochemical apparatus is made having a generator section containing electrochemical cells, a fresh gaseous feed fuel inlet, a gaseous feed oxidant inlet, and at least one hot gaseous spent fuel recirculation channel, where the spent fuel recirculation channel, passes from the generator chamber to combine with the fresh feed fuel inlet to form a reformable mixture, where a reforming chamber contains an outer portion containing reforming material, an inner portion preferably containing a mixer nozzle and a mixer-diffuser, and a middle portion for receiving spent fuel, where the mixer nozzle and mixer-diffuser are preferably both within the reforming chamber and substantially exterior to the main portion of the apparatus, where the reformable mixture flows up and then backward before contacting the reforming material, and the mixer nozzle can operate below 400 C. 1 figure.

  9. Genomagnetic assay for electrochemical detection of osteogenic differentiation in mesenchymal stem cells.

    PubMed

    Erdem, Arzum; Duruksu, Gokhan; Congur, Gulsah; Karaoz, Erdal

    2013-09-21

    The osteogenic differentiation of mesenchymal stem cells (MSCs) was assessed by determining the gene expression levels of proteins; osteocalcin (OSC), osteonectin (OSN) and osteopontin (OSP) based on electrochemical detection protocol combined with genomagnetic assay in parallel to real-time PCR analysis. Genomagnetic assay was performed using streptavidin coated commercial magnetic particles (magnetic beads, MBs) in combination with single-use electrochemical sensor technology. A biotinylated DNA probe was immobilized onto streptavidin coated magnetic particles, and then the hybridization process of the probe with its complementary DNA was performed. The oxidation signals of DNA electroactive bases guanine and adenine were measured voltammetrically using a pencil graphite electrode (PGE) before and after the hybridization process of OSC/OSN/OSP probe sequences with their complementary target sequences. The selectivity of the genomagnetic assay was also tested using each DNA probe individually related to osteogenic differentiations. The voltammetric detection of osteogenic differentiations was confirmed selectively by real-time PCR analysis. PMID:23884209

  10. Electrochemical cell apparatus having an integrated reformer-mixer nozzle-mixer diffuser

    DOEpatents

    Shockling, Larry A. (Plum Borough, PA)

    1991-01-01

    An electrochemical apparatus (10) is made having a generator section (22) containing electrochemical cells (16), a fresh gaseous feed fuel inlet (28), a gaseous feed oxidant inlet (30), and at least one hot gaseous spent fuel recirculation channel (46), where the spent fuel recirculation channel (46), passes from the generator chamber (22) to combine with the fresh feed fuel inlet (28) to form a reformable mixture, where a reforming chamber (54) contains an outer portion containing reforming material (56), an inner portion preferably containing a mixer nozzle (50) and a mixer-diffuser (52), and a middle portion (64) for receiving spent fuel, where the mixer nozzle (50) and mixer-diffuser (52) are preferably both within the reforming chamber (54) and substantially exterior to the main portion of the apparatus, where the reformable mixture flows up and then backward before contacting the reforming material (56), and the mixer nozzle (50) can operate below 400.degree. C.

  11. Indium tin oxide based chip for optical and electrochemical characterization of protein–cell interaction

    NASA Astrophysics Data System (ADS)

    Choi, Yong Hyun; Min, Junhong; Cho, Sungbo

    2015-06-01

    Analysis on the interaction between proteins and cells is required for understanding the cellular behaviour and response. In this article, we characterized the adhesion and growth of 293/GFP cells on fetal bovine serum (FBS) coated indium tin oxide (ITO) electrode. Using optical and electrochemical measurement, it was able to detect the adsorption of the protein on the surface of the ITO electrode dependent on the concentration of the protein in the immersing solution or the immersing time. An increase in the amount of the adsorbed serum protein resulted in a decrease in anodic peak current and an increase in the charge transfer resistance extracted from the equivalent circuit fitting analysis. More cells adhered and proliferated on the ITO electrode which was pre-immersed in FBS medium rather than bare electrode. The effect of the FBS on cell behaviors was reflected in the impedance monitoring of cells at 21.5 kHz.

  12. In-situ quantification of solid oxide fuel cell electrode microstructure by electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Yanxiang; Chen, Yu; Chen, Fanglin

    2015-03-01

    Three-dimensional (3D) microstructure of solid oxide fuel cell electrodes plays critical roles in determining fuel cell performance. The state-of-the-art quantification technique such as X-ray computed tomography enables direct calculation of geometric factors by 3D microstructure reconstruction. Taking advantages of in-situ, fast-responding and low cost, electrochemical impedance spectroscopy represented by distribution of relaxation time (DRT) is a novel technique to estimate geometric properties of fuel cell electrodes. In this study, we employed the anode supported cells with the cell configuration of Ni-YSZ || YSZ || LSM-YSZ as an example and compared the tortuosity factor of pores of the anode substrate layer by X-ray computed tomography and DRT analysis. Good agreement was found, validating the feasibility of in-situ microstructural quantification by using the DRT technique.

  13. Electrochemical storage

    NASA Technical Reports Server (NTRS)

    Thaller, L. H.

    1984-01-01

    The source of the problem within the individual single cell which is related to the stochastic properties of cell populations and to the actual electrochemistry and chemistry taking place is described. The complications which arise in multicell batteries to show how different electrochemistries might alleviate or accentuate these problems is described. The concept of the electrochemical system is introduced to show how certain shortcomings of the single cell/battery string concept can be circumvented. Some of these electrochemical systems permit performance characteristics that are impossible by using conventional battery design philosophies. Projections for energy density and performance characteristics of the concepts are addressed.

  14. An optically transparent thin-layer electrochemical cell for the study of vibrational circular dichroism of chiral redox-active molecules

    NASA Astrophysics Data System (ADS)

    Domingos, Sérgio R.; Luyten, Henk; van Anrooij, Fred; Sanders, Hans J.; Bakker, Bert H.; Buma, Wybren J.; Hartl, František; Woutersen, Sander

    2013-03-01

    An optically transparent thin-layer electrochemical (OTTLE) cell with a locally extended optical path has been developed in order to perform vibrational circular dichroism (VCD) spectroscopy on chiral molecules prepared in specific oxidation states by means of electrochemical reduction or oxidation. The new design of the electrochemical cell successfully addresses the technical challenges involved in achieving sufficient infrared absorption. The VCD-OTTLE cell proves to be a valuable tool for the investigation of chiral redox-active molecules.

  15. Chitosan-lithium triflate electrolyte in secondary lithium cells

    NASA Astrophysics Data System (ADS)

    Morni, N. M.; Arof, A. K.

    Films prepared from high molecular weight chitosan are shown to exhibit the highest electrical conductivity of 2.14×10 -7 S cm -1. The electrical conductivity is further enhanced to 1.03×10 -5 S cm -1 when ethylene carbonate (EC) is used as a plasticizer. X-ray diffraction (XRD) shows that EC disrupts the crystalline nature of chitosan acetate. Infrared (IR) spectroscopy reveals a shift in the amide band from 1590 to 1575 cm -1 on addition of LiCF 3SO 3. A film with a (chitosan+0.4 g EC) to LiCF 3SO 3 ratio of 80:20 gives the highest electrical conductivity of 3.0×10 -4 S cm -1. This film is used as an electrolyte for the fabrication of chitosan-based secondary cells, viz., Li/chitosan-EC-LiCF 3SO 3/V 2O 5. The characteristics of the cells are presented in this paper.

  16. Toward the early evaluation of therapeutic effects: an electrochemical platform for ultrasensitive detection of apoptotic cells.

    PubMed

    Zhang, Jing-Jing; Zheng, Ting-Ting; Cheng, Fang-Fang; Zhang, Jian-Rong; Zhu, Jun-Jie

    2011-10-15

    The ability for early evaluation of therapeutic effects is a significant challenge in leukemia research. To address this challenge, we developed a novel electrochemical platform for ultrasensitive and selective detection of apoptotic cells in response to therapy. In order to construct the platform, a novel three-dimensional (3-D) architecture was initially fabricated after combining nitrogen-doped carbon nanotubes and gold nanoparticles via a layer-by-layer method. The formed architecture provided an effective matrix for annexin V with high stability and bioactivity to enhance sensitivity. On the basis of the specific recognition between annexin V and phosphatidylserine on the apoptotic cell membrane, the annexin V/3-D architecture interface showed a predominant capability for apoptotic cell capture. Moreover, a lectin-based nanoprobe was designed by noncovalent assembly of concanavalin A on CdTe quantum dots (QDs)-labeled silica nanospheres with poly(allylamine hydrochloride) as a linker. This nanoprobe incorporated both the specific carbohydrate recognition and the multilabeled QDs-based signal amplification. By coupling with the QDs-based nanoprobe and electrochemical stripping analysis, the proposed sandwich-type cytosensor showed an excellent analytical performance for the ultrasensitive detection of apoptotic cells (as low as 48 cells), revealing great potential toward the early evaluation of therapeutic effects. PMID:21888423

  17. 3D CFD ELECTROCHEMICAL AND HEAT TRANSFER MODEL OF AN INTERNALLY MANIFOLDED SOLID OXIDE ELECTROLYSIS CELL

    SciTech Connect

    Grant L. Hawkes; James E. O'Brien; Greg Tao

    2011-11-01

    A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created to model high-temperature electrolysis cell performance and steam electrolysis in an internally manifolded planar solid oxide electrolysis cell (SOEC) stack. This design is being evaluated at the Idaho National Laboratory for hydrogen production from nuclear power and process heat. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT. 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, operating potential, steam-electrode gas composition, oxygen-electrode gas composition, current density and hydrogen production over a range of stack operating conditions. Single-cell and five-cell results will be presented. Flow distribution through both models is discussed. Flow enters from the bottom, distributes through the inlet plenum, flows across the cells, gathers in the outlet plenum and flows downward making an upside-down ''U'' shaped flow pattern. Flow and concentration variations exist downstream of the inlet holes. Predicted mean outlet hydrogen and steam concentrations vary linearly with current density, as expected. Effects of variations in operating temperature, gas flow rate, oxygen-electrode and steam-electrode current density, and contact resistance from the base case are presented. Contour plots of local electrolyte temperature, current density, and Nernst potential indicate the effects of heat transfer, reaction cooling/heating, and change in local gas composition. Results are discussed for using this design in the electrolysis mode. Discussion of thermal neutral voltage, enthalpy of reaction, hydrogen production, cell thermal efficiency, cell electrical efficiency, and Gibbs free energy are discussed and reported herein.

  18. Electrochemical Detection of Circadian Redox Rhythm in Cyanobacterial Cells via Extracellular Electron Transfer.

    PubMed

    Nishio, Koichi; Pornpitra, Tunanunkul; Izawa, Seiichiro; Nishiwaki-Ohkawa, Taeko; Kato, Souichiro; Hashimoto, Kazuhito; Nakanishi, Shuji

    2015-06-01

    Recent research on cellular circadian rhythms suggests that the coupling of transcription-translation feedback loops and intracellular redox oscillations is essential for robust circadian timekeeping. For clarification of the molecular mechanism underlying the circadian rhythm, methods that allow for the dynamic and simultaneous detection of transcription/translation and redox oscillations in living cells are needed. Herein, we report that the cyanobacterial circadian redox rhythm can be electrochemically detected based on extracellular electron transfer (EET), a process in which intracellular electrons are exchanged with an extracellular electrode. As the EET-based method is non-destructive, concurrent detection with transcription/translation rhythm using bioluminescent reporter strains becomes possible. An EET pathway that electrochemically connected the intracellular region of cyanobacterial cells with an extracellular electrode was constructed via a newly synthesized electron mediator with cell membrane permeability. In the presence of the mediator, the open circuit potential of the culture medium exhibited temperature-compensated rhythm with approximately 24 h periodicity. Importantly, such circadian rhythm of the open circuit potential was not observed in the absence of the electron mediator, indicating that the EET process conveys the dynamic information regarding the intracellular redox state to the extracellular electrode. These findings represent the first direct demonstration of the intracellular circadian redox rhythm of cyanobacterial cells. PMID:25975263

  19. Hydrogen generation from artificial sea water in a semiconductor septum electrochemical photovoltaic cell.

    PubMed

    Tien, H T; Chen, J W

    1989-05-01

    Visible light of the solar spectrum is directly converted to stored chemical energy of hydrogen from artificial sea water in a novel electrochemical photovoltaic cell. The principal element of the cell, modeled after the photosynthetic thylakoid membrane, is a semiconductor septum made of polycrystalline n-CdSe thin film deposited on nickel foil, which separates two aqueous solutions. Under short-circuit conditions, vigorous hydrogen evolution was seen at the Ni surface and continued as long as the cell was operated. The novel cell, the concept of which was derived from pigmented bilayer lipid membrane studies, is easy to construct, simple to operate, and appears to be a practical approach to the photochemical conversion and storage of solar energy. PMID:2755987

  20. A whole-cell electrochemical biosensing system based on bacterial inward electron flow for fumarate quantification.

    PubMed

    Si, Rong-Wei; Zhai, Dan-Dan; Liao, Zhi-Hong; Gao, Lu; Yong, Yang-Chun

    2015-06-15

    Fumarate is of great importance as it is an oncometabolite as well as food spoilage indicator. However, cost-effective and fast quantification method for fumarate is lacking although it is urgently required. This work developed an electrochemical whole-cell biosensing system for fumarate quantification. A sensitive inwards electric output (electron flow from electrode into bacteria) responded to fumarate in Shewanella oneidensis MR-1 was characterized, and an electrochemical fumarate biosensing system was developed without genetic engineering. The biosensing system delivered symmetric current peak immediately upon fumarate addition, where the peak area increased in proportion to the increasing fumarate concentration with a wide range of 2 ?M-10 mM (R(2)=0.9997). The limit of detection (LOD) and the limit of quantification (LOQ) are 0.83 ?M and 1.2 ?M, respectively. This biosensing system displayed remarkable specificity to fumarate against other possible interferences. It was also successfully applied to samples of apple juice and kidney tissue. This study added new dimension to electrochemical biosensor design, and provide a simple, cost-effective, fast and robust tool for fumarate quantification. PMID:25558872

  1. An ultra-high vacuum electrochemical flow cell for in situ/operando soft X-ray spectroscopy study

    SciTech Connect

    Bora, Debajeet K., E-mail: debajeet.bora@empa.ch, E-mail: jguo@lbl.gov; Glans, Per-Anders; Pepper, John; Liu, Yi-Sheng; Guo, J.-H., E-mail: debajeet.bora@empa.ch, E-mail: jguo@lbl.gov [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Du, Chun; Wang, Dunwei [Department of Chemistry, Boston College, Boston, Massachusetts 02467 (United States)] [Department of Chemistry, Boston College, Boston, Massachusetts 02467 (United States)

    2014-04-15

    An in situ flow electrochemical cell has been designed and fabricated to allow better seal under UHV chamber thus to achieve a good signal to noise ratio in fluorescence yield detection of X-ray absorption spectra for spectroelectrochemical study. The cell also stabilizes the thin silicon nitride membrane window in an effective manner so that the liquid cell remains intact during X-ray absorption experiments. With the improved design of the liquid cell, electrochemical experiments such as cyclic voltammetry have been performed for 10 cycles with a good stability of sample window. Also an operando electrochemical experiment during photoelectrochemistry has been performed on n-type hematite electrode deposited on silicon nitride window. The experiment allows us to observe the formation of two extra electronic transitions before pre edge of O K-edge spectra.

  2. Electrochemical Performance and Microbial Characterization of Thermophilic Microbial Fuel Cells

    NASA Astrophysics Data System (ADS)

    Wrighton, K. C.; Agbo, P.; Brodie, E. L.; Weber, K. A.; Desantis, T. Z.; Anderson, G. L.; Coates, J. D.

    2007-12-01

    Significant research effort is currently focused on microbial fuel cells (MFC) as a source of renewable energy. To date, most of these efforts have concentrated on MFCs operating at mesophilic temperatures. However, many previous studies have reported on the superiority of thermophilic conditions in anaerobic digestion and demonstrated a net gain in energy yield, in terms of methane, relative to the increased energy requirements of operation. Because of this, our recent studies on MFCs focused on investigating the operation and microbiology associated with thermophilic MFCs operating at 55°C. Over 100-day operation, these MFCs were highly stable and achieved a maximum power density of 24mW/m2 and a columbic efficiency of 89 percent with acetate as the sole electron donor. In order to characterize the microbial community involved in thermophilic electricity generation, DNA and RNA were isolated from the electrode and PhyloChip analyses performed. Exploring the changes in the microbial community over time in electricity producing MFC revealed an increase in relative abundance of populations belonging to the Firmicutes, Chloroflexi, and alpha Proteobacteria by at least one order of magnitude. In contrast, these populations decreased in the open circuit and no electron donor amended controls. In order to better characterize the active microbial populations, we enriched and isolated a novel organism, strain JR, from samples collected from an operating MFC. Based on 16S rRNA sequence analysis strain JR was a member of the family Peptococcaceae, within the Phylum Firmicutes, clustering with Thermincola ferriacetica (98 percent similarity). Phenotypic characterization revealed that strain JR was capable of thermophilic dissimilatory reduction of insoluble electron acceptors such as amorphous Fe(III); as well as reduction of the model quinone 2,6-anthraquinone disulfonate. Thermincola strain JR was also capable of producing current by coupling acetate oxidation to anodic electron transfer. This represents the first organism isolated from a thermophilic microbial fuel cell and also the first representative of this genus capable of anodic electron transfer. The results of this study indicate the potential advantages for thermophilic MFCs and the novel microbiology associated with their operation.

  3. High-temperature "spectrochronopotentiometry": correlating electrochemical performance with in situ Raman spectroscopy in solid oxide fuel cells.

    PubMed

    Kirtley, John D; Halat, David M; McIntyre, Melissa D; Eigenbrodt, Bryan C; Walker, Robert A

    2012-11-20

    Carbon formation or "coking" on solid oxide fuel cell (SOFC) anodes adversely affects performance by blocking catalytic sites and reducing electrochemical activity. Quantifying these effects, however, often requires correlating changes in SOFC electrochemical efficiency measured during operation with results from ex situ measurements performed after the SOFC has been cooled and disassembled. Experiments presented in this work couple vibrational Raman spectroscopy with chronopotentiometry to observe directly the relationship between graphite deposited on nickel cermet anodes and the electrochemical performance of SOFCs operating at 725 °C. Raman spectra from Ni cermet anodes at open circuit voltage exposed to methane show a strong vibrational band at 1556 cm(-1) assigned to the "G" mode of highly ordered graphite. When polarized in the absence of a gas-phase fuel, these carbon-loaded anodes operate stably, oxidizing graphite to form CO and CO(2). Disappearance of graphite intensity measured in the Raman spectra is accompanied by a steep ?0.8 V rise in the cell potential needed to keep the SOFC operating under constant current conditions. Continued operation leads to spectroscopically observable Ni oxidation and another steep rise in cell potential. Time-dependent spectroscopic and electrochemical measurements pass through correlated equivalence points providing unequivocal, in situ evidence that identifies how SOFC performance depends on the chemical condition of its anode. Chronopotentiometric data are used to quantify the oxide flux necessary to eliminate the carbon initially present on the SOFC anode, and data show that the oxidation mechanisms responsible for graphite removal correlate directly with the electrochemical condition of the anode as evidenced by voltammetry and impedance measurements. Electrochemically oxidizing the Ni anode damages the SOFC significantly and irreversibly. Anodes that have been reconstituted following electrochemical oxidation of carbon and Ni show qualitatively different kinetics of carbon removal, and the electrochemical performance of these systems is characterized by low maximum currents and large polarization resistances. PMID:23046116

  4. Detection of propylene using two zirconia-based electrochemical cells

    SciTech Connect

    Hibino, Takashi; Kuwahara, Yoshitaka [National Industrial Research Inst. of Nagoya (Japan)] [National Industrial Research Inst. of Nagoya (Japan); Wang, S. [New Energy and Industrial Technology Development Organization, Nagoya (Japan)] [New Energy and Industrial Technology Development Organization, Nagoya (Japan)

    1999-01-01

    A sensor element detecting propylene at high temperatures has been fabricated by attaching two Pd or Pt/YSZ/Au cells together where the Pd or Pt electrodes were located on the inside of the assembly. The sensing properties of the sensor at 750 C were investigated using a flowing mixture of propylene, methane, carbon monoxide, and oxygen, the concentrations of which were in the range of 100 to 700 ppm. The sensor element using the Pd electrode had a high sensitivity to propylene, but a low selectivity to propylene over methane. The use of the Pt electrode made it possible to significantly improve the selectivity to propylene over methane, because the catalytic activities of the Pt electrode for the oxidation of methane were far lower than that of the Pd electrode and as low as that of the Au electrode. The current signal at a fixed oxygen concentration of 300 ppm was almost proportional to the propylene concentration. In addition, the current signal at a fixed propylene concentration of 350 ppm was not significantly affected by changing the oxygen concentration.

  5. Cyanobacteria as Cell Factories to Produce Plant Secondary Metabolites

    PubMed Central

    Xue, Yong; He, Qingfang

    2015-01-01

    Cyanobacteria represent a promising platform for the production of plant secondary metabolites. Their capacity to express plant P450 proteins, which have essential functions in the biosynthesis of many plant secondary metabolites, makes cyanobacteria ideal for this purpose, and their photosynthetic capability allows cyanobacteria to grow with simple nutrient inputs. This review summarizes the advantages of using cyanobacteria to transgenically produce plant secondary metabolites. Some techniques to improve heterologous gene expression in cyanobacteria are discussed. PMID:25973419

  6. Electrochemical cell apparatus having axially distributed entry of a fuel-spent fuel mixture transverse to the cell lengths

    DOEpatents

    Reichner, Philip (Plum Borough, PA); Dollard, Walter J. (Churchill Borough, PA)

    1991-01-01

    An electrochemical apparatus (10) is made having a generator section (22) containing axially elongated electrochemical cells (16), a fresh gaseous feed fuel inlet (28), a gaseous feed oxidant inlet (30), and at least one gaseous spent fuel exit channel (46), where the spent fuel exit channel (46) passes from the generator chamber (22) to combine with the fresh feed fuel inlet (28) at a mixing apparatus (50), reformable fuel mixture channel (52) passes through the length of the generator chamber (22) and connects with the mixing apparatus (50), that channel containing entry ports (54) within the generator chamber (22), where the axis of the ports is transverse to the fuel electrode surfaces (18), where a catalytic reforming material is distributed near the reformable fuel mixture entry ports (54).

  7. Effect of gaseous composition on cell growth and secondary metabolite production in suspension culture of Stizolobium hassjoo cells

    Microsoft Academic Search

    S.-Y. Huang; C.-J. Chou

    2000-01-01

    The gaseous composition is an important factor affecting the performance of plant cell cultures. Gaseous metabolites, especially O2, CO2 and C2H4, play important roles in cell physiology. Forced aeration in bioreactors usually results in poor cell growth and secondary metabolite production. In this work, the effects of gaseous metabolites on cell growth, secondary metabolite formation as well as PPO activity

  8. Supporting electrodes for solid oxide fuel cells and other electrochemical devices

    DOEpatents

    Sprenkle, Vincent L. (Richland, WA); Canfield, Nathan L. (Kennewick, WA); Meinhardt, Kerry (Kennewick, WA); Stevenson, Jeffry W. (Richland, WA)

    2008-04-01

    An electrode supported electrolyte membrane includes an electrode layer 630 facing an electrolyte layer 620. The opposing side of the electrode layer 630 includes a backing layer 640 of a material with a thermal expansion coefficient approximately equal to the thermal expansion coefficient of the electrolyte layer 620. The backing layer 640 is in a two dimensional pattern that covers only a portion of the electrolyte layer 630. An electrochemical cell such as a SOFC is formed by providing a cathode layer 610 on an opposing side of the electrolyte layer 620.

  9. Engineering charge injection interfaces in hybrid light-emitting electrochemical cells.

    PubMed

    Roldán-Carmona, Cristina; Akatsuka, Takeo; Sessolo, Michele; Watkins, Scott E; Bolink, Henk J

    2014-11-26

    Light-emitting electrochemical cells (LECs) consists of a thin film of an ionic organic semiconductor sandwiched between two electrodes. Because of the large density of ions, LECs are often reported to perform independently on the electrodes work function. Here we use metal oxides as charge injection layers and demonstrate that, although electroluminescence is observed independently of the electrodes used, the device performances are strongly dependent on the choice of the interface materials. Relying on metal oxide charge injection layers, such hybrid devices are of interest for real lighting applications and could pave the way for new efficient, stable, low-cost lighting sources. PMID:25372865

  10. Electrochemical photovoltaic cells based on n-GaAs in propylene carbonate

    SciTech Connect

    Langmuir, M.E.; Hoenig, P.; Rauh, R.D.

    1981-11-01

    Electrochemical photovoltaic cells (EPC's) have been characterized based on n-GaAs and propylene carbonate electrolytes. Photovoltages are limited to approximately 0.7 v due to electrode corrosion and lack of specific adsorption by the redox systems studied. Polarization of photo and counterelectrodes, resulting from low redox solubilities and electrolyte conductivities, are responsible for lower fill factors and short-circuit photocurrents for nonaqueous compared to aqueous EPC's. Potentially, these losses can be offset by higher voltages and long-term stabilities, particularly if specifically adsorbing redox couples can be found. 17 refs.

  11. Hydrophilic Electrode For An Alkaline Electrochemical Cell, And Method Of Manufacture

    DOEpatents

    Senyarich, Stephane (Mornac, FR); Cocciantelli, Jean-Michel (Bordeaux, FR)

    2000-03-07

    A negative electrode for an alkaline electrochemical cell. The electrode comprises an active material and a hydrophilic agent constituted by small cylindrical rods of polyolefin provided with hydrophilic groups. The mean length of the rods is less than 50 microns and the mean diameter thereof is less than 20 microns. A method of manufacturing a negative electrode in which hydrophilic rods are made by fragmenting long polyolefin fibers having a mean diameter of less than 20 microns by oxidizing them, with the rods being mixed with the active material and the mixture being applied to a current conductor.

  12. Biological capacitance studies of anodes in microbial fuel cells using electrochemical impedance spectroscopy.

    PubMed

    Lu, Zhihao; Girguis, Peter; Liang, Peng; Shi, Haifeng; Huang, Guangtuan; Cai, Lankun; Zhang, Lehua

    2015-07-01

    It is known that cell potential increases while anode resistance decreases during the start-up of microbial fuel cells (MFCs). Biological capacitance, defined as the apparent capacitance attributed to biological activity including biofilm production, plays a role in this phenomenon. In this research, electrochemical impedance spectroscopy was employed to study anode capacitance and resistance during the start-up period of MFCs so that the role of biological capacitance was revealed in electricity generation by MFCs. It was observed that the anode capacitance ranged from 3.29 to 120 mF which increased by 16.8 % to 18-20 times over 10-12 days. Notably, lowering the temperature and arresting biological activity via fixation by 4 % para formaldehyde resulted in the decrease of biological capacitance by 16.9 and 62.6 %, indicating a negative correlation between anode capacitance and anode resistance of MFCs. Thus, biological capacitance of anode should play an important role in power generation by MFCs. We suggest that MFCs are not only biological reactors and/or electrochemical cells, but also biological capacitors, extending the vision on mechanism exploration of electron transfer, reactor structure design and electrode materials development of MFCs. PMID:25656699

  13. Electrochemical impedance measurement of prostate cancer cells using carbon nanotube array electrodes in a microfluidic channel

    NASA Astrophysics Data System (ADS)

    Heung Yun, Yeo; Dong, Zhongyun; Shanov, Vesselin N.; Schulz, Mark J.

    2007-11-01

    Highly aligned multi-wall carbon nanotubes were synthesized in the shape of towers and embedded into fluidic channels as electrodes for impedance measurement of LNCaP human prostate cancer cells. Tower electrodes up to 8 mm high were grown and easily peeled off a silicon substrate. The nanotube electrodes were then successfully soldered onto patterned printed circuit boards and cast into epoxy under pressure. After polishing the top of the tower electrodes, RF plasma was used to enhance the electrocatalytic effect by removing excess epoxy and activating the open end of the nanotubes. Electrodeposition of Au particles on the plasma-treated tower electrodes was done at a controlled density. Finally, the nanotube electrodes were embedded into a polydimethylsiloxane (PDMS) channel and electrochemical impedance spectroscopy was carried out with different conditions. Preliminary electrochemical impedance spectroscopy results using deionized water, buffer solution, and LNCaP prostate cancer cells showed that nanotube electrodes can distinguish the different solutions and could be used in future cell-based biosensor development.

  14. Electrochemical photovoltaic and photoelectrochemical storage cells based on II-IV polycrystalline thin-film materials

    SciTech Connect

    Wallace, W.L.

    1983-05-01

    Research on electrochemical photovoltaic cells incorporating thin film CdSe and CdSe/sub x/Te/sub 1-x/ photoanodes has progressed to the point where efficiencies of up to 7% can be achieved on small area electrodes using a polysulfide electrolyte. Higher efficiencies can be obtained in alternate electrolytes in significantly less stable systems. The major limitations on cell efficiency are associated with the open circuit voltage and fill factor. At present, the most promising photoelectrochemical storage system is an in situ three electrode cell under investigation at the Weizmann Institute and consists of an n-CdSe/sub x/Te/sub 1-x/ photoanode and CoS counterelectrode in a sulfide/polysulfide electrolyte and a Sn/SnS storage electrode isolated in an aqueous sulfide electrolyte.

  15. Electrochemical photovoltaic and photoelectrochemical storage cells based on II-VI polycrystalline thin film materials

    SciTech Connect

    Wallace, W.L.

    1983-06-01

    Research on electrochemical photovoltaic cells incorporating thin film CdSe and CdSe /SUB x/ Te /SUB 1-x/ photoanodes has progressed to the point where efficiencies of up to 7% can be achieved on small area electrodes using a polysulfide electrolyte. Higher efficiencies can be obtained in alternate electrolytes in significantly less stable systems. The major limitations on cell efficiency are associated with the open circuit voltage and fill factor. At present, the most promising photoelectrochemical storage system is an in situ three electrode cell which consists of an n-CdSe /SUB x/ Te /SUB 1-x/ photoanode and CoS counterelectrode in a sulfide/polysulfide electrolyte and a Sn/SnS storage electrode isolated in an aqueous sulfide electrolyte.

  16. Navigating the transcriptional roadmap regulating plant secondary cell wall deposition

    PubMed Central

    Hussey, Steven G.; Mizrachi, Eshchar; Creux, Nicky M.; Myburg, Alexander A.

    2013-01-01

    The current status of lignocellulosic biomass as an invaluable resource in industry, agriculture, and health has spurred increased interest in understanding the transcriptional regulation of secondary cell wall (SCW) biosynthesis. The last decade of research has revealed an extensive network of NAC, MYB and other families of transcription factors regulating Arabidopsis SCW biosynthesis, and numerous studies have explored SCW-related transcription factors in other dicots and monocots. Whilst the general structure of the Arabidopsis network has been a topic of several reviews, they have not comprehensively represented the detailed protein–DNA and protein–protein interactions described in the literature, and an understanding of network dynamics and functionality has not yet been achieved for SCW formation. Furthermore the methodologies employed in studies of SCW transcriptional regulation have not received much attention, especially in the case of non-model organisms. In this review, we have reconstructed the most exhaustive literature-based network representations to date of SCW transcriptional regulation in Arabidopsis. We include a manipulable Cytoscape representation of the Arabidopsis SCW transcriptional network to aid in future studies, along with a list of supporting literature for each documented interaction. Amongst other topics, we discuss the various components of the network, its evolutionary conservation in plants, putative modules and dynamic mechanisms that may influence network function, and the approaches that have been employed in network inference. Future research should aim to better understand network function and its response to dynamic perturbations, whilst the development and application of genome-wide approaches such as ChIP-seq and systems genetics are in progress for the study of SCW transcriptional regulation in non-model organisms. PMID:24009617

  17. Method of forming a plasma sprayed interconnection layer on an electrode of an electrochemical cell

    DOEpatents

    Spengler, Charles J. (Murrysville, PA); Folser, George R. (Lower Burrell, PA); Vora, Shailesh D. (Monroeville, PA); Kuo, Lewis (Monroeville, PA); Richards, Von L. (Anyola, IN)

    1995-01-01

    A dense, substantially gas-tight, electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO.sub.3 particles doped with an element selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by plasma spraying doped LaCrO.sub.3 powder, preferably compensated with chromium as Cr.sub.2 O.sub.3 and/or dopant element, preferably by plasma arc spraying; and, (C) heating the doped and compensated LaCrO.sub.3 layer to about 1100.degree. C. to 1300.degree. C. to provide a dense, substantially gas-tight, substantially hydration-free, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the unselected portion of the air electrode, and a fuel electrode can be applied to the solid electrolyte, to provide an electrochemical cell.

  18. Engineering high yields of secondary metabolites in Rubia cell cultures through transformation with rol genes.

    PubMed

    Bulgakov, Victor P; Shkryl, Yuri N; Veremeichik, Galina N

    2010-01-01

    Among the different methods currently used to improve yields of secondary metabolites in cultured plant cells, the method involving transformation by rol genes represents an example of relatively new technology. These genes, isolated from plasmids of the plant pathogen Agrobacterium rhizogenes, are potential activators of secondary metabolism in transformed cells from the Solanaceae, Araliaceae, Rubiaceae, Vitaceae, and Rosaceae families. In some cases, the activator effect of individual rol genes was sufficient to overcome the inability of cultured plant cells to produce large amounts of secondary metabolites. Stimulation of production characteristics of cultured plant cells mediated by the rol genes was shown to be remarkably stable over long-term cultivation. In this chapter, we describe transformation of Rubia cordifolia L. cells with the rol genes as an example of metabolic engineering of secondary metabolites. PMID:20552455

  19. A Synopsis of Interfacial Phenomena in Lithium-Based Polymer Electrolyte Electrochemical Cells

    NASA Technical Reports Server (NTRS)

    Baldwin, Richard S.; Bennett, William R.

    2007-01-01

    The interfacial regions between electrode materials, electrolytes and other cell components play key roles in the overall performance of lithium-based batteries. For cell chemistries employing lithium metal, lithium alloy or carbonaceous materials (i.e., lithium-ion cells) as anode materials, a "solid electrolyte interphase" (SEI) layer forms at the anode/electrolyte interface, and the properties of this "passivating" layer significantly affect the practical cell/battery quality and performance. A thin, ionically-conducting SEI on the electrode surface can beneficially reduce or eliminate undesirable side reactions between the electrode and the electrolyte, which can result in a degradation in cell performance. The properties and phenomena attributable to the interfacial regions existing at both anode and cathode surfaces can be characterized to a large extent by electrochemical impedance spectroscopy (EIS) and related techniques. The intention of the review herewith is to support the future development of lithium-based polymer electrolytes by providing a synopsis of interfacial phenomena that is associated with cell chemistries employing either lithium metal or carbonaceous "composite" electrode structures which are interfaced with polymer electrolytes (i.e., "solvent-free" as well as "plasticized" polymer-binary salt complexes and single ion-conducting polyelectrolytes). Potential approaches to overcoming poor cell performance attributable to interfacial effects are discussed.

  20. Experimental aspects of combined NOx and SO2 removal from flue-gas mixture in an integrated wet scrubber-electrochemical cell system.

    PubMed

    Chandrasekara Pillai, K; Chung, Sang Joon; Raju, T; Moon, Il-Shik

    2009-07-01

    The objective of this work was to study the effect of some operating conditions on the simultaneous removal of NO(x) and SO2 from simulated NO-SO2-air flue-gas mixtures in a scrubber column. The gaseous components were absorbed into 6M HNO3 electrolyte in the scrubber in a counter-current mode, and were oxidatively removed by the Ag(II) mediator oxidant electrochemically generated in an electrochemical cell set-up. The integration of the electrochemical cell with the scrubber set-up ensured continuous regeneration of the Ag(II) mediator and its repeated reuse for NO(x) and SO2 removal purpose, thereby avoiding: (1) the usage of chemicals continuously for oxidation and (2) the production of secondary waste. The influences of packing material (raschig glass rings, raschig poly(vinylidene) fluoride rings, Jaeger tri-pack perfluoroalkoxy spheres), feed concentrations of NO and SO2 (100-400 ppm NO and 100-400 ppm SO2), superficial gas velocity (0.061-0.61ms(-1)) and liquid velocity (0.012-0.048 ms(-1)) were investigated. The raschig glass rings with high surface area provided highest NO removal efficiency. NO and NO(x) showed decreasing abatement at higher feed concentrations. The removal of nitrogen components was faster and also greater, when SO2 co-existed in the feed. Whereas the gas flow rate decreased the removal efficiency, the liquid flow rate increased it for NO and NOx. The flow rate effects were analyzed in terms of gas/liquid residence time and superficial liquid velocity/superficial gas velocity ratio. SO2 removal was total under all conditions. PMID:19500817

  1. Intracellular Cytokine Production by Dengue Virus–specific T cells Correlates with Subclinical Secondary Infection

    PubMed Central

    Hatch, Steven; Endy, Tim P.; Thomas, Stephen; Mathew, Anuja; Potts, James; Pazoles, Pamela; Libraty, Daniel H.; Gibbons, Robert

    2011-01-01

    The pathophysiology of dengue virus infection remains poorly understood, although secondary infection is strongly associated with more severe disease. In the present study, we performed a nested, case-control study comparing the responses of pre-illness peripheral blood mononuclear cells between children who would subsequently develop either subclinical or symptomatic secondary infection 6–11 months after the baseline blood samples were obtained and frozen. We analyzed intracellular cytokine production by CD4+ and CD8+ cells in response to stimulation with dengue antigen. We found higher frequencies of dengue virus–specific TNF?, IFN?-, and IL-2–producing T cells among schoolchildren who subsequently developed subclinical infection, compared with those who developed symptomatic secondary dengue virus infection. Although other studies have correlated immune responses during secondary infection with severity of disease, to our knowledge this is the first study to demonstrate a pre-infection dengue-specific immune response that correlates specifically with a subclinical secondary infection. PMID:21335561

  2. A novel and simple cell-based electrochemical impedance biosensor for evaluating the combined toxicity of DON and ZEN.

    PubMed

    Gu, Wenshu; Zhu, Pei; Jiang, Donglei; He, Xingxing; Li, Yun; Ji, Jian; Zhang, Lijuan; Sun, Yange; Sun, Xiulan

    2015-08-15

    In this study, a novel and simple cell-based electrochemical biosensor was developed to assess the individual and combined toxicity of deoxynivalenol (DON) and zearalenone (ZEN) on BEL-7402 cells. The sensor was fabricated by modification with AuNPs, p-aminothiophenol, and folic acid in succession. The BEL-7402 cells which had a good activity were adhered on the electrode through the high affinity between the folate receptor and folic acid selectivity. We used the collagen to maintain the cell adhesion and viability. Electrochemical impedance spectroscopy (EIS) was developed to evaluate the individual and combined toxicity of DON and ZEN. Our results indicate that DON and ZEN caused a marked decrease in the cell viability in a dose-dependent manner. The value of electrochemical impedance spectroscopy decreased with the concentration of DON and ZEN in range of 0.1-20, 0.1-50?g/ml with the detection limit as 0.03, 0.05?g/ml, respectively, the IC50 for DON and ZEN as obtained by the proposed electrochemical method were 7.1?g/ml and 24.6?g/ml, respectively, and the combination of two mycotoxins appears to generate an additive response. The electrochemical cytotoxicity evaluation result was confirmed by biological assays. Compared to conventional methods, this electrochemical test is inexpensive, highly sensitive, and fast to respond, with long-term monitoring and real-time measurements. The proposed method provides a new avenue for evaluating the toxicity of mycotoxins. PMID:25863342

  3. Electrochemical device

    DOEpatents

    Grimes, Patrick G. (Westfield, NJ); Einstein, Harry (Springfield, NJ); Bellows, Richard J. (Westfield, NJ)

    1988-01-12

    A tunnel protected electrochemical device features channels fluidically communicating between manifold, tunnels and cells. The channels are designed to provide the most efficient use of auxiliary power. The channels have a greater hydraulic pressure drop and electrical resistance than the manifold. This will provide a design with the optimum auxiliary energy requirements.

  4. Solid polymer electrolyte electrochemical storage cell containing a redox shuttle additive for overcharge protection

    DOEpatents

    Richardson, Thomas J. (Oakland, CA); Ross, Philip N. (Moraga, CA)

    1999-01-01

    A class of organic redox shuttle additives is described, preferably comprising nitrogen-containing aromatics compounds, which can be used in a high temperature (85.degree. C. or higher) electrochemical storage cell comprising a positive electrode, a negative electrode, and a solid polymer electrolyte to provide overcharge protection to the cell. The organic redox additives or shuttles are characterized by a high diffusion coefficient of at least 2.1.times.10.sup.-8 cm.sup.2 /second and a high onset potential of 2.5 volts or higher. Examples of such organic redox shuttle additives include an alkali metal salt of 1,2,4-triazole, an alkali metal salt of imidazole, 2,3,5,6-tetramethylpyrazine, 1,3,5-tricyanobenzene, and a dialkali metal salt of 3-4-dihydroxy-3-cyclobutene-1,2-dione.

  5. Electrodes and electrochemical storage cells utilizing tin-modified active materials

    DOEpatents

    Anani, Anaba (Lauderhill, FL); Johnson, John (Calverton, NY); Lim, Hong S. (Agoura Hills, CA); Reilly, James (Bellport, NY); Schwarz, Ricardo (Los Alamos, NM); Srinivasan, Supramaniam (College Station, TX)

    1995-01-01

    An electrode has a substrate and a finely divided active material on the substrate. The active material is ANi.sub.x-y-z Co.sub.y Sn.sub.z, wherein A is a mischmetal or La.sub.1-w M.sub.w, M is Ce, Nd, or Zr, w is from about 0.05 to about 1.0, x is from about 4.5 to about 5.5, y is from 0 to about 3.0, and z is from about 0.05 to about 0.5. An electrochemical storage cell utilizes such an electrode as the anode. The storage cell further has a cathode, a separator between the cathode and the anode, and an electrolyte.

  6. Hardware development and application specifications for Li/CoO2 electrochemical cells

    NASA Astrophysics Data System (ADS)

    Beard, Kirby W.

    Considerable progress has been made in evaluating Li/LixCoO2 electrochemical cells and determining the effects of various parameters. A year-long series of tests involving dozens of samples and hundreds of cycles is summarized. Test results are based on actual working hardware cells/batteries in the 1 to 5 Ah range. Differences between parallel, flat plate and spirally wrapped electrode configurations are considered, and a full spectrum of real world use and abuse conditions are discussed. With a solid basis of performance capabilities demonstrated, potential projections and technology comparisons can be made to conventional rechargeable battery systems. For moderate cycle life and low to moderate discharge rate applications, the Li/LixCoO2 technology demonstrates at least 3-4 times the energy density capabilities and has far less stringent application requirements.

  7. Volatile resistance states in electrochemical metallization cells enabling non-destructive readout of complementary resistive switches.

    PubMed

    van den Hurk, Jan; Linn, Eike; Zhang, Hehe; Waser, Rainer; Valov, Ilia

    2014-10-24

    Redox-based resistive memory cells exhibit changes of OFF or intermediate resistance values over time and even ON states can be completely lost in certain cases. The stability of these resistance states and the time until resistance loss strongly depends on the materials system. On the basis of electrical measurements and chemical analysis we found a viable explanation for these volatile resistance states (VRSs) in Ag-GeSx-based electrochemical metallization memory cells and identified a technological application in the field of crossbar memories. Complementary resistive switches usually suffer from the necessity of a destructive read-out procedure increasing wear and reducing read-out speed. From our analysis we deduced a solution to use the VRS as an inherent selector mechanism without the need for additional selector devices. PMID:25266966

  8. Solid oxide electrolysis cell analysis by means of electrochemical impedance spectroscopy: A review

    NASA Astrophysics Data System (ADS)

    Nechache, A.; Cassir, M.; Ringuedé, A.

    2014-07-01

    High temperature water electrolysis based on Solid Oxide Electrolysis Cell (SOEC) is a very promising solution to produce directly pure hydrogen. However, degradation issues occurring during operation still represent a scientific and technological barrier in view of its development at an industrial scale. Electrochemical Impedance Spectroscopy (EIS) is a powerful in-situ fundamental tool adapted to the study of SOEC systems. Hence, after a quick presentation of EIS principle and data analysis methods, this review demonstrates how EIS can be used: (i) to characterize the performance and mechanisms of SOEC electrodes; (ii) as a complementary tool to study SOEC degradation processes for different cell configurations, in addition to post-test tools such as scanning electron microscopy (SEM) or X-ray diffraction (XRD). The use of EIS to establish a systematic SOEC analysis is introduced as well.

  9. Laccases Direct Lignification in the Discrete Secondary Cell Wall Domains of Protoxylem1[W][OPEN

    PubMed Central

    Schuetz, Mathias; Benske, Anika; Smith, Rebecca A.; Watanabe, Yoichiro; Tobimatsu, Yuki; Ralph, John; Demura, Taku; Ellis, Brian; Samuels, A. Lacey

    2014-01-01

    Plants precisely control lignin deposition in spiral or annular secondary cell wall domains during protoxylem tracheary element (TE) development. Because protoxylem TEs function to transport water within rapidly elongating tissues, it is important that lignin deposition is restricted to the secondary cell walls in order to preserve the plasticity of adjacent primary wall domains. The Arabidopsis (Arabidopsis thaliana) inducible VASCULAR NAC DOMAIN7 (VND7) protoxylem TE differentiation system permits the use of mutant backgrounds, fluorescent protein tagging, and high-resolution live-cell imaging of xylem cells during secondary cell wall development. Enzymes synthesizing monolignols, as well as putative monolignol transporters, showed a uniform distribution during protoxylem TE differentiation. By contrast, the oxidative enzymes LACCASE4 (LAC4) and LAC17 were spatially localized to secondary cell walls throughout protoxylem TE differentiation. These data support the hypothesis that precise delivery of oxidative enzymes determines the pattern of cell wall lignification. This view was supported by lac4lac17 mutant analysis demonstrating that laccases are necessary for protoxylem TE lignification. Overexpression studies showed that laccases are sufficient to catalyze ectopic lignin polymerization in primary cell walls when exogenous monolignols are supplied. Our data support a model of protoxylem TE lignification in which monolignols are highly mobile once exported to the cell wall, and in which precise targeting of laccases to secondary cell wall domains directs lignin deposition. PMID:25157028

  10. Photoelectrochemical and Electrochemical Characterization of Sub-Micro-Gram Amounts of Organic Semiconductors Using Scanning Droplet Cell Microscopy.

    PubMed

    Kollender, Jan Philipp; Gasiorowski, Jacek; Sariciftci, Niyazi S; Mardare, Andrei I; Hassel, Achim Walter

    2014-07-31

    A model organic semiconductor (MDMO-PPV) was used for testing a modified version of a photoelectrochemical scanning droplet cell microscope (PE-SDCM) adapted for use with nonaqueous electrolytes and containing an optical fiber for localized illumination. The most attractive features of the PE-SDCM are represented by the possibility of addressing small areas on the investigated substrate and the need of small amounts of electrolyte. A very small amount (ng) of the material under study is sufficient for a complete electrochemical and photoelectrochemical characterization due to the scanning capability of the cell. The electrochemical behavior of the polymer was studied in detail using potentiostatic and potentiodynamic investigations as well as electrochemical impedance spectroscopy. Additionally, the photoelectrochemical properties were investigated under illumination conditions, and the photocurrents found were at least 3 orders of magnitude higher than the dark (background) current, revealing the usefulness of this compact microcell for photovoltaic characterizations. PMID:25101149

  11. 3D CFD Electrochemical and Heat Transfer Model of an Integrated-Planar Solid Oxide Electrolysis Cells

    Microsoft Academic Search

    Grant Hawkes; James E. OBrien

    2008-01-01

    A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created to model high-temperature electrolysis cell performance and steam electrolysis in a new novel integrated planar porous-tube supported solid oxide electrolysis cell (SOEC). The model is of several integrated planar cells attached to a ceramic support tube. This design is being evaluated with modeling at the Idaho National Laboratory. Mass,

  12. Electrochemical and physical analysis of a Li-ion cell cycled at elevated temperature

    SciTech Connect

    Shim, Joongpyo; Kostecki, Robert; Richardson, Thomas; Song, Xiangyun; Striebel, Kathryn A.

    2002-06-21

    Laboratory-size LiNi0.8Co0.15Al0.05O2/graphite lithium-ion pouch cells were cycled over 100 percent DOD at room temperature and 60 degrees C in order to investigate high-temperature degradation mechanisms of this important technology. Capacity fade for the cell was correlated with that for the individual components, using electrochemical analysis of the electrodes and other diagnostic techniques. The high-temperature cell lost 65 percent of its initial capacity after 140 cycles at 60 degrees C compared to only 4 percent loss for the cell cycled at room temperature. Cell ohmic impedance increased significantly with the elevated temperature cycling, resulting in some of loss of capacity at the C/2 rate. However, as determined with slow rate testing of the individual electrodes, the anode retained most of its original capacity, while the cathode lost 65 percent, even when cycled with a fresh source of lithium. Diagnostic evaluation of cell components including XRD, Raman, CSAFM and suggest capacity loss occurs primarily due to a rise in the impedance of the cathode, especially at the end-of-charge. The impedance rise may be caused in part by a loss of the conductive carbon at the surface of the cathode and/or by an organic film on the surface of the cathode that becomes non-ionically conductive at low lithium content.

  13. Electrochemical fuel cell generator having an internal and leak tight hydrocarbon fuel reformer

    DOEpatents

    Dederer, J.T.; Hager, C.A.

    1998-03-31

    An electrochemical fuel cell generator configuration is made having a generator section which contains a plurality of axially elongated fuel cells, each cell containing a fuel electrode, air electrode, and solid oxide electrolyte between the electrodes, in which axially elongated dividers separate portions of the fuel cells from each other, and where at least one divider also reforms a reformable fuel gas mixture prior to electricity generation reactions, the at least one reformer-divider is hollow having a closed end and an open end entrance for a reformable fuel mixture to pass to the closed end of the divider and then reverse flow and pass back along the hollowed walls to be reformed, and then finally to pass as reformed fuel out of the open end of the divider to contact the fuel cells, and further where the reformer-divider is a composite structure having a gas diffusion barrier of metallic foil surrounding the external walls of the reformer-divider except at the entrance to prevent diffusion of the reformable gas mixture through the divider, and further housed in an outer insulating jacket except at the entrance to prevent short-circuiting of the fuel cells by the gas diffusion barrier. 10 figs.

  14. The effect of Ni on the microstructures and electrochemical properties of Si-Ti base alloys for lithium secondary batteries.

    PubMed

    Ahn, Deuk Kyu; Song, Jong-Jin; Ahn, Hyo-Jun; Cho, Jong Soo; Moon, Jeong Tak; Park, Won-Wook; Sohn, Keun Yong

    2013-05-01

    This paper presents the microstructures and electrochemical properties of Si-Ti-Ni alloys of various compositions prepared by a rapid solidification process. Si-15Ti-(0-25 at%)Ni alloy ingots prepared by arc-melting was melt-spun to produce thin strip of -15 Om thickness. The Si-Ni-Ti alloy electrode were fabricated by mixing the active powdered materials (88 wt%) with ketjen black (4 wt%) as a conductive material and polyamide-imide binder (PAI, 8 wt.%) dissolved in N-methyl-2-pyrrolidinone (NMP). Results showed that the microstructures of melt-spun Si-Ti-Ni ribbons consist of silicon, TiSi2, Si7Ni4Ti4, and NiSi2 phases depending on the composition. As the content of nickel increased in silicon matrix, TiSi2 phase disappeared while Si7Ni4Ti4 and NiSi2 phases are generated. The cycle efficiency of Si65Ti15Ni20 and Si60Ti15Ni25 alloys was significantly improved because of the increased volume fraction of Si7Ni4Ti4 and NiSi2 phases and fine particulated silicon phase. PMID:23858893

  15. An electrochemical cell for in operando studies of lithium/sodium batteries using a conventional x-ray powder diffractometer

    NASA Astrophysics Data System (ADS)

    Shen, Yanbin; Pedersen, Erik E.; Christensen, Mogens; Iversen, Bo B.

    2014-10-01

    An electrochemical cell has been designed for powder X-ray diffraction studies of lithium ion batteries (LIB) and sodium ion batteries (SIB) in operando with high time resolution using a conventional powder X-ray diffractometer. The cell allows for studies of both anode and cathode electrode materials in reflection mode. The cell design closely mimics that of standard battery testing coin cells and allows obtaining powder X-ray diffraction patterns under representative electrochemical conditions. In addition, the cell uses graphite as the X-ray window instead of beryllium, and it is easy to operate and maintain. Test examples on lithium insertion/extraction in two spinel-type LIB electrode materials (Li4Ti5O12 anode and LiMn2O4 cathode) are presented as well as first results on sodium extraction from a layered SIB cathode material (Na0.84Fe0.56Mn0.44O2).

  16. An electrochemical cell for in operando studies of lithium/sodium batteries using a conventional x-ray powder diffractometer.

    PubMed

    Shen, Yanbin; Pedersen, Erik E; Christensen, Mogens; Iversen, Bo B

    2014-10-01

    An electrochemical cell has been designed for powder X-ray diffraction studies of lithium ion batteries (LIB) and sodium ion batteries (SIB) in operando with high time resolution using a conventional powder X-ray diffractometer. The cell allows for studies of both anode and cathode electrode materials in reflection mode. The cell design closely mimics that of standard battery testing coin cells and allows obtaining powder X-ray diffraction patterns under representative electrochemical conditions. In addition, the cell uses graphite as the X-ray window instead of beryllium, and it is easy to operate and maintain. Test examples on lithium insertion/extraction in two spinel-type LIB electrode materials (Li4Ti5O12 anode and LiMn2O4 cathode) are presented as well as first results on sodium extraction from a layered SIB cathode material (Na0.84Fe0.56Mn0.44O2). PMID:25362421

  17. Starting to Gel: How Arabidopsis Seed Coat Epidermal Cells Produce Specialized Secondary Cell Walls

    PubMed Central

    Voiniciuc, C?t?lin; Yang, Bo; Schmidt, Maximilian Heinrich-Wilhelm; Günl, Markus; Usadel, Björn

    2015-01-01

    For more than a decade, the Arabidopsis seed coat epidermis (SCE) has been used as a model system to study the synthesis, secretion and modification of cell wall polysaccharides, particularly pectin. Our detailed re-evaluation of available biochemical data highlights that Arabidopsis seed mucilage is more than just pectin. Typical secondary wall polymers such as xylans and heteromannans are also present in mucilage. Despite their low abundance, these components appear to play essential roles in controlling mucilage properties, and should be further investigated. We also provide a comprehensive community resource by re-assessing the mucilage phenotypes of almost 20 mutants using the same conditions. We conduct an in-depth functional evaluation of all the SCE genes described in the literature and propose a revised model for mucilage production. Further investigation of SCE cells will improve our understanding of plant cell walls. PMID:25658798

  18. Inkjet printed bilayer light-emitting electrochemical cells for display and lighting applications.

    PubMed

    Lindh, E Mattias; Sandström, Andreas; Edman, Ludvig

    2014-10-29

    A new bilayer light-emitting electrochemical cell (LEC) device, which allows well-defined patterned light emission through an easily adjustable, mask-free, and additive fabrication process, is reported. The bilayer stack comprises an inkjet-printed lattice of micrometer-sized electrolyte droplets, in a "filled" or "patterned" lattice configuration. On top of this, a thin layer of light-emitting compound is deposited from solution. The light emission is demonstrated to originate from regions proximate to the interfaces between the inkjetted electrolyte, the light-emitting compound, and one electrode, where bipolar electron/hole injection and electrochemical doping are facilitated by ion motion. By employing KCF3 SO3 in poly(ethylene glycol) as the electrolyte, Super Yellow as the light-emitting compound, and two air-stabile electrodes, it is possible to realize filled lattice devices that feature uniform yellow-green light emission to the naked eye, and patterned lattice devices that deliver well-defined and high-contrast static messages with a pixel density of 170 PPI. PMID:25070524

  19. Improving the carrier balance of light-emitting electrochemical cells based on ionic transition metal complexes.

    PubMed

    Su, Hai-Ching; Hsu, Jia-Hong

    2015-04-29

    Recently, solid-state light-emitting electrochemical cells (LECs) based on ionic transition metal complexes (iTMCs) have attracted much research interest since they have the advantages of a simple device structure, a low operation voltage and compatibility with air-stable electrodes. These properties enable LECs to be cost-effective, versatile and power-efficient organic light-emitting sources. However, it is generally not easy to modify the molecular structure to achieve balanced carrier mobilities without altering the photoluminescence quantum yield of the iTMC. Furthermore, the carrier balance and the consequent device efficiency of single-layered LECs would not be easy to optimize since no carrier injection and transport layers can be used. In this perspective, some reported techniques to improve carrier balance of LECs based on iTMCs are described and reviewed. The importance and impact of these studies are highlighted. The effects on device lifetime and turn-on time because of employing these techniques to improve the carrier balance are also discussed. This perspective concludes that even with electrochemically doped layers, improving the carrier balance of LECs would be required for realizing efficient electroluminescent emission from simple-structure organic light-emitting sources. PMID:25407946

  20. Carbon-Ring Microelectrode Arrays for Electrochemical Imaging of Single Cell Exocytosis: Fabrication and Characterization

    PubMed Central

    Lin, Yuqing; Trouillon, Raphaël; Svensson, Maria I.; Keighron, Jacqueline D.; Cans, Ann-Sofie; Ewing, Andrew G.

    2012-01-01

    Fabrication of carbon microelectrode arrays, with up to 15 electrodes in total tips as small as 10 to 50 ?m, is presented. The support structures of microelectrodes were obtained by pulling multiple quartz capillaries together to form hollow capillary arrays before carbon deposition. Carbon ring microelectrodes were deposited by pyrolysis of acetylene in the lumen of these quartz capillary arrays. Each carbon deposited array tip was filled with epoxy, followed by beveling of the tip of the array to form a deposited carbon-ring microelectrode array (CRMA). Both the number of the microelectrodes in the array and the tip size are independently tunable. These CRMAs have been characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, and electrogenerated chemiluminescence. Additionally, the electrochemical properties were investigated with steady-state voltammetry. In order to demonstrate the utility of these fabricated microelectrodes in neurochemistry, CRMAs containing eight microring electrodes were used for electrochemical monitoring of exocytotic events from single PC12 cells. Subcellular temporal heterogeneities in exocytosis (ie. cold spots vs. hot spots) were successfully detected with the CRMAs. PMID:22339586

  1. Mechanism for resistive switching in chalcogenide-based electrochemical metallization memory cells

    NASA Astrophysics Data System (ADS)

    Zhuge, Fei; Li, Kang; Fu, Bing; Zhang, Hongliang; Li, Jun; Chen, Hao; Liang, Lingyan; Gao, Junhua; Cao, Hongtao; Liu, Zhimin; Luo, Hao

    2015-05-01

    It has been reported that in chalcogenide-based electrochemical metallization (ECM) memory cells (e.g., As2S3:Ag, GeS:Cu, and Ag2S), the metal filament grows from the cathode (e.g., Pt and W) towards the anode (e.g., Cu and Ag), whereas filament growth along the opposite direction has been observed in oxide-based ECM cells (e.g., ZnO, ZrO2, and SiO2). The growth direction difference has been ascribed to a high ion diffusion coefficient in chalcogenides in comparison with oxides. In this paper, upon analysis of OFF state I-V characteristics of ZnS-based ECM cells, we find that the metal filament grows from the anode towards the cathode and the filament rupture and rejuvenation occur at the cathodic interface, similar to the case of oxide-based ECM cells. It is inferred that in ECM cells based on the chalcogenides such as As2S3:Ag, GeS:Cu, and Ag2S, the filament growth from the cathode towards the anode is due to the existence of an abundance of ready-made mobile metal ions in the chalcogenides rather than to the high ion diffusion coefficient.

  2. THERMAL AND ELECTROCHEMICAL THREE DIMENSIONAL CFD MODEL OF A PLANAR SOLID OXIDE ELECTROLYSIS CELL

    SciTech Connect

    Grant Hawkes; Jim O'Brien; Carl Stoots; Steve Herring; Mehrdad Shahnam

    2005-07-01

    A three-dimensional computational fluid dynamics (CFD) model has been 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 an electrolysis stack. Details of the model geometry are specific to a stack that was fabricated by Ceramatec , Inc. and tested at the Idaho National Laboratory. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT2. 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 experimental results obtained from an actual ten-cell stack tested at INL.

  3. Electrochemical performance and transport properties of a Nafion membrane in a hydrogen-bromine cell environment

    NASA Technical Reports Server (NTRS)

    Baldwin, Richard S.

    1987-01-01

    The overall energy conversion efficiency of a hydrogen-bromine energy storage system is highly dependent upon the characteristics and performance of the ion-exchange membrane utilized as a half-cell separator. The electrochemical performance and transport properties of a duPont Nafion membrane in an aqueous HBr-Br2 environment were investigated. Membrane conductivity data are presented as a function of HBr concentration and temperature for the determination of ohmic voltage losses across the membrane in an operational cell. Diffusion-controlled bromine permeation rates and permeabilities are presented as functions of solution composition and temperature. Relationships between the degree of membrane hydration and the membrane transport characteristics are discussed. The solution chemistry of an operational hydrogen-bromine cell undergoing charge from 45% HBr to 5% HBr is discussed, and, based upon the experimentally observed bromine permeation behavior, predicted cell coulombic losses due to bromine diffusion through the membrane are presented as a function of the cell state-of-charge.

  4. On-site applicability of hydrogen peroxide producing microbial electrochemical cells (MECs) coupled with UV in wastewater disinfection study

    EPA Science Inventory

    Background: There is an increased interest in the application of microbial electrochemical cell (MEC) for the recovery of value-added products such as hydrogen gas and hydrogen peroxide (H2O2) from wastewater. H2O2 has strong oxidation capability and produces hydroxyl radicals wh...

  5. Thermal and electrochemical durability of carbonaceous composites used as a bipolar plate of proton exchange membrane fuel cell

    Microsoft Academic Search

    Taro Kinumoto; Keita Nagano; Tomoki Tsumura; Masahiro Toyoda

    2010-01-01

    Thermal and electrochemical durability of carbonaceous composite plates, which are made from graphite powders and a resin for use as bipolar plates of PEMFC (proton exchange membrane fuel cell), were investigated. The thermal durability was investigated by TG (thermal gravimetry) coupled with DTA (differential thermal analysis) technique under air up to 600°C. A weight loss was significant over 300°C, but

  6. The compromises of printing organic electronics: a case study of gravure-printed light-emitting electrochemical cells.

    PubMed

    Hernandez-Sosa, Gerardo; Tekoglu, Serpil; Stolz, Sebastian; Eckstein, Ralph; Teusch, Claudia; Trapp, Jannik; Lemmer, Uli; Hamburger, Manuel; Mechau, Norman

    2014-05-28

    Light-emitting electrochemical cells (LECs) are fabricated by gravure printing. The compromise between device performance and printing quality is correlated to the ink formulation and the printing process. It is shown that the rheological properties of the ink formulations of LECs can be tailored without changing the chemical composition of the material blend. PMID:24616075

  7. Electrochemical studies of an unsupported PtIr electrocatalyst as a bifunctional oxygen electrode in a unitized regenerative fuel cell

    Microsoft Academic Search

    Ho-Young Jung; Branko N. Popov

    2009-01-01

    The electrochemical performance of an unsupported PtIr electrocatalyst was evaluated as a bifunctional oxygen electrode in a unitized regenerative fuel cell (URFC). The catalyst was a mixture of unsupported Pt black and Ir black catalysts in varying proportions. The performance of the unsupported PtIr catalyst was studied by using a rotating ring disc electrode (RRDE) and linear sweep voltammetry (LSV).

  8. Boosting the voltage of a salinity-gradient-power electrochemical cell by means of complex-forming solutions

    E-print Network

    Carati, Andrea

    Boosting the voltage of a salinity-gradient-power electrochemical cell by means of complex-forming solutions M. Marino, L. Misuri, A. Carati, and D. Brogioli Citation: Applied Physics Letters 105, 033901 solution J. Chem. Phys. 113, 3519 (2000); 10.1063/1.1287785 This article is copyrighted as indicated

  9. Method of preparing porous, rigid ceramic separators for an electrochemical cell

    DOEpatents

    Bandyopadhyay, Gautam (Naperville, IL); Dusek, Joseph T. (Downers Grove, IL)

    1981-01-01

    Porous, rigid separators for electrochemical cells are prepared by first calcining particles of ceramic material at temperatures above about 1200.degree. C. for a sufficient period of time to reduce the sinterability of the particles. A ceramic powder that has not been calcined is blended with the original powder to control the porosity of the completed separator. The ceramic blend is then pressed into a sheet of the desired shape and sintered at a temperature somewhat lower than the calcination temperature. Separator sheets of about 1 to 2.5 mm thickness and 30 to 70% porosity can be prepared by this technique. Ceramics such as yttria, magnesium oxide and magnesium-aluminum oxide have advantageously been used to form separators by this method.

  10. Non-doped solid-state white light-emitting electrochemical cells employing the microcavity effect.

    PubMed

    Lin, Guan-Rung; Chen, Hsiao-Fan; Shih, Hsien-Chang; Hsu, Jia-Hong; Chang, Yi; Chiu, Chih-Hung; Cheng, Chia-Yu; Yeh, Yun-Shiuan; Su, Hai-Ching; Wong, Ken-Tsung

    2015-03-14

    Solid-state white light-emitting electrochemical cells (LECs) have attracted research attention owing to their advantages of simple device structure, low operation voltage and compatibility with solution processes. In this work, we demonstrate a simple approach to obtain white electroluminescence (EL) from non-doped LECs based on a blue-emitting complex. With a relatively thicker emissive layer, red emission can be additionally enhanced by the microcavity effect when the recombination zone moves to appropriate positions. Hence, white EL can be harvested by combining blue emission from the complex and red emission from the microcavity effect. These non-doped white LECs show external quantum efficiencies and power efficiencies up to 5% and 12 lm W(-1), respectively. These results show that efficient white EL can be obtained in simple non-doped LECs. PMID:25679194

  11. A colour-tunable, weavable fibre-shaped polymer light-emitting electrochemical cell

    NASA Astrophysics Data System (ADS)

    Zhang, Zhitao; Guo, Kunping; Li, Yiming; Li, Xueyi; Guan, Guozhen; Li, Houpu; Luo, Yongfeng; Zhao, Fangyuan; Zhang, Qi; Wei, Bin; Pei, Qibing; Peng, Huisheng

    2015-04-01

    The emergence of wearable electronics and optoelectronics requires the development of devices that are not only highly flexible but can also be woven into textiles to offer a truly integrated solution. Here, we report a colour-tunable, weavable fibre-shaped polymer light-emitting electrochemical cell (PLEC). The fibre-shaped PLEC is fabricated using all-solution-based processes that can be scaled up for practical applications. The design has a coaxial structure comprising a modified metal wire cathode and a conducting aligned carbon nanotube sheet anode, with an electroluminescent polymer layer sandwiched between them. The fibre shape offers unique and promising advantages. For example, the luminance is independent of viewing angle, the fibre-shaped PLEC can provide a variety of different and tunable colours, it is lightweight, flexible and wearable, and it can potentially be woven into light-emitting clothes for the creation of smart fabrics.

  12. New innovative materials for advanced electrochemical applications in battery and fuel cell systems

    NASA Astrophysics Data System (ADS)

    Voß, S.; Kollmann, H.; Kollmann, W.

    The advanced material POLYMET is an innovative high tech polymer with a three-dimensional polymeric structure metallized with an enclosing coating of different kinds of metals or alloys. The result is a range of tailor-made, microporous structures on a designable scale. By varying the metals and alloys, it is possible to draw upon extremely diverse areas of applications such as battery systems, fuel cells, filters or efficient catalysts as well as air regeneration systems, e.g. in aerospace. The three-dimensional structure of metallized high tech woven or non-woven materials or foams causes a lot of advantages such as high conductivity, high corrosion resistance, flexibility or mechanical strength. Therefore, POLYMET is suitable for, e.g. current collectors or gas diffusion layers in energy storage systems. They supply an economic and environmental alternative material to improve functional electrochemical systems.

  13. Simultaneous microbial and electrochemical reductions of vanadium (V) with bioelectricity generation in microbial fuel cells.

    PubMed

    Zhang, Baogang; Tian, Caixing; Liu, Ying; Hao, Liting; Liu, Ye; Feng, Chuanping; Liu, Yuqian; Wang, Zhongli

    2015-03-01

    Simultaneous microbial and electrochemical reductions of vanadium (V) with bioelectricity generation were realized in microbial fuel cells (MFCs). With initial V(V) concentrations of 75 mg/l and 150 mg/l in anolyte and catholyte, respectively, stable power output of 419±11 mW/m(2) was achieved. After 12h operation, V(V) concentration in the catholyte decreased to the value similar to that of the initial one in the anolyte, meanwhile it was nearly reduced completely in the anolyte. V(IV) was the main reduction product, which subsequently precipitated, acquiring total vanadium removal efficiencies of 76.8±2.9%. Microbial community analysis revealed the emergence of the new species of Deltaproteobacteria and Bacteroidetes as well as the enhanced Spirochaetes mainly functioned in the anode. This study opens new pathways to successful remediation of vanadium contamination. PMID:25536507

  14. Electrodes including a polyphosphazene cyclomatrix, methods of forming the electrodes, and related electrochemical cells

    DOEpatents

    Gering, Kevin L; Stewart, Frederick F; Wilson, Aaron D; Stone, Mark L

    2014-10-28

    An electrode comprising a polyphosphazene cyclomatrix and particles within pores of the polyphosphazene cyclomatrix. The polyphosphazene cyclomatrix comprises a plurality of phosphazene compounds and a plurality of cross-linkages. Each phosphazene compound of the plurality of phosphazene compounds comprises a plurality of phosphorus-nitrogen units, and at least one pendant group bonded to each phosphorus atom of the plurality of phosphorus-nitrogen units. Each phosphorus-nitrogen unit is bonded to an adjacent phosphorus-nitrogen unit. Each cross-linkage of the plurality of cross-linkages bonds at least one pendant group of one phosphazene compound of the plurality of phosphazene compounds with the at least one pendant group of another phosphazene compound of the plurality of phosphazene compounds. A method of forming a negative electrode and an electrochemical cell are also described.

  15. Characteristics of boron doped mesophase pitch-based carbon fibers as anode materials for lithium secondary cells

    SciTech Connect

    Tamaki, Toshio; Kawamura, Toshifumi; Yamazaki, Yoshinori

    1998-07-01

    Mesophase pitch-based Carbon Fibers(MCF) have been investigated as anode materials for lithium secondary cells by examining their physical and electrochemical properties. Discharge capacity and initial charge-discharge efficiency of the materials were studied in relation to the heat treatment temperatures of MCF. MCF heat treated at about 3,000 C gave high discharge capacity over 310mAh/g, good efficiency (93%) and superior current capability of 600mA/g (6mA/cm2). On the other hand, to improve the battery capacity, Boron was doped to the fiber about several {degree} by adding B{sub 4}C to the pre-carbonized milled fibers and then heat-treated up to 3,000 C in Ar. Then heat treated at 2,500 C under vacuum condition to remove remained B{sub 4}C. The structure of Boron-doped fibers was characterized and compared with that of non-doped standard fibers, and also Li ion battery performances are evaluated. The Boron-doped MCF indicated improvement in graphitization and increased discharge capacity as high as 360mAh/g. The voltammograms of both fibers are different from each other. The cell mechanism is discussed based on the unique structure of Boron-doping to the MCF is very effective for the battery performance.

  16. Electrochemical investigation of lithium/potassium carbonate eutectic for application in modeling the molten carbonate fuel cell cathode

    NASA Astrophysics Data System (ADS)

    McCoy, L.; Schuman, M.

    1986-04-01

    A program involving the design, construction, and operation of a high-temperature cell equipped with a rotating gold disk electrode has been carried out with the objective of identifying and quantifying the principal oxide species present in molten LiKCO3 electrolytes using electrochemical measurements. The dependence of the current on electrode rotational speed at 750 to 800 C indicates that the data are typical of the convective/diffusive transport of an electroactive species from the bulk electrolyte. The reverse is true at 650 C, where the current increases with an increasing voltage sweep rate but is little affected by the speed of electrode rotation. In the latter case, a current by chemical reaction occurring within the electrode boundary layer is indicated. The linear current-voltage increase observed at the lower temperature in the presence of about 20 mol % 02 has not been accounted for. Graphical analysis of the data taken with air and CO2 sparged electrolyte at 750 and 800C indicates the electroactive species to be the superoxide ion. Computer studies of the same data usi ng regression analysis methodology indicate that the current may instead arise from the reduction of the peroxide ion concurrently with other electroactive material derived from secondary catalytic reactions or electrolyte impurities. Additional data will be required to support either conclusion with certainty. Detailed studies of the electrochemistry of the LiKCO3 electrolyte over a broader range of temperatures and sparge gas compositions are recommended as a means of providing a second basis for identifying the electrode reactions.

  17. TCP24 modulates secondary cell wall thickening and anther endothecium development

    PubMed Central

    Wang, Han; Mao, Yanfei; Yang, Jun; He, Yuke

    2015-01-01

    miR319-targeted TCP genes are believed to regulate cell division in leaves and floral organs. However, it remains unknown whether these genes are involved in cell wall development. Here, we report that TCP24 negatively regulates secondary wall thickening in floral organs and roots. The overexpression of the miR319a-resistant version of TCP24 in Arabidopsis disrupted the thickening of secondary cell walls in the anther endothecium, leading to male sterility because of arrested anther dehiscence and pollen release. Several genes linked to secondary cell wall biogenesis and thickening were down-regulated in these transgenic plants. By contrast, the inhibition of TCP24 using the ectopic expression of a TCP24-SRDX repressor fusion protein, or the silencing of TCP genes by miR319a overexpression, increased cell wall lignification and the enhanced secondary cell wall thickening. Our results suggest that TCP24 acts as an important regulator of secondary cell wall thickening and modulates anther endothecium development. PMID:26157444

  18. Electrochemical Investigation of a Microbial Solar Cell Reveals a Nonphotosynthetic Biocathode Catalyst

    PubMed Central

    Glaven, Richard H.; Wang, Zheng; Zhou, Jing; Vora, Gary J.; Tender, Leonard M.

    2013-01-01

    Microbial solar cells (MSCs) are microbial fuel cells (MFCs) that generate their own oxidant and/or fuel through photosynthetic reactions. Here, we present electrochemical analyses and biofilm 16S rRNA gene profiling of biocathodes of sediment/seawater-based MSCs inoculated from the biocathode of a previously described sediment/seawater-based MSC. Electrochemical analyses indicate that for these second-generation MSC biocathodes, catalytic activity diminishes over time if illumination is provided during growth, whereas it remains relatively stable if growth occurs in the dark. For both illuminated and dark MSC biocathodes, cyclic voltammetry reveals a catalytic-current–potential dependency consistent with heterogeneous electron transfer mediated by an insoluble microbial redox cofactor, which was conserved following enrichment of the dark MSC biocathode using a three-electrode configuration. 16S rRNA gene profiling showed Gammaproteobacteria, most closely related to Marinobacter spp., predominated in the enriched biocathode. The enriched biocathode biofilm is easily cultured on graphite cathodes, forms a multimicrobe-thick biofilm (up to 8.2 ?m), and does not lose catalytic activity after exchanges of the reactor medium. Moreover, the consortium can be grown on cathodes with only inorganic carbon provided as the carbon source, which may be exploited for proposed bioelectrochemical systems for electrosynthesis of organic carbon from carbon dioxide. These results support a scheme where two distinct communities of organisms develop within MSC biocathodes: one that is photosynthetically active and one that catalyzes reduction of O2 by the cathode, where the former partially inhibits the latter. The relationship between the two communities must be further explored to fully realize the potential for MSC applications. PMID:23603672

  19. In-situ Photoelectron Microspectroscopy and Imaging of Electrochemical Processes at the Electrodes of a Self-driven Cell

    PubMed Central

    Bozzini, Benedetto; Amati, Matteo; Gregoratti, Luca; Kiskinova, Maya

    2013-01-01

    The challenges in development of solid oxide fuel cells (SOFCs) are reducing their dimensions and increasing their efficiency and durability, which requires physicochemical characterization at micro-scales of the device components during operation conditions. Recently, the unique potential of scanning photoelectron microscopy (SPEM) has been demonstrated by in-situ studies of externally-driven SOFCs, which mimic real devices. Here we overcome the gap between model and real systems using a single-chamber Ni|YSZ|Mn SOFC, supporting a range of self-driven electrochemical reactions in variable gas environments and temperatures. The reported SPEM results, obtained during spontaneous electrochemical processes occurring in reactive gas ambient, demonstrate the chemical evolution of electrodic material, in particular the lateral distribution of the oxidation state and the induced local potential, clearly marking out the electrochemically most active micro-regions of the Ni anode. PMID:24092014

  20. In-situ photoelectron microspectroscopy and imaging of electrochemical processes at the electrodes of a self-driven cell.

    PubMed

    Bozzini, Benedetto; Amati, Matteo; Gregoratti, Luca; Kiskinova, Maya

    2013-01-01

    The challenges in development of solid oxide fuel cells (SOFCs) are reducing their dimensions and increasing their efficiency and durability, which requires physicochemical characterization at micro-scales of the device components during operation conditions. Recently, the unique potential of scanning photoelectron microscopy (SPEM) has been demonstrated by in-situ studies of externally-driven SOFCs, which mimic real devices. Here we overcome the gap between model and real systems using a single-chamber Ni|YSZ|Mn SOFC, supporting a range of self-driven electrochemical reactions in variable gas environments and temperatures. The reported SPEM results, obtained during spontaneous electrochemical processes occurring in reactive gas ambient, demonstrate the chemical evolution of electrodic material, in particular the lateral distribution of the oxidation state and the induced local potential, clearly marking out the electrochemically most active micro-regions of the Ni anode. PMID:24092014

  1. Aging Studies of Sr-doped LaCrO3\\/YSZ\\/Pt Cells for an Electrochemical NOx Sensor

    Microsoft Academic Search

    Seung-Wan Song; L. Peter Martin; Robert S. Glass; Erica P. Murray; Jaco H. Visser; Richard E. Soltis; Robert F. Novak; D J Kubinski

    2005-01-01

    The stability and NOâ sensing performance of electrochemical cells of the structure Sr-doped LaCrO{sub 3-δ} (LSC)\\/yttria-stabilized zirconia (YSZ)\\/Pt are being investigated for use in NOâ aftertreatment systems in diesel vehicles. Among the requirements for NOâ sensor materials in these systems are stability and long lifetime (up to ten years) in the exhaust environment. In this study, cell aging effects were

  2. Use of high-temperature gas-tight electrochemical cells to measure electronic transport and thermodynamics in metal oxides

    Microsoft Academic Search

    J. H. Park; B. Ma; E. T. Park

    1997-01-01

    By using a gas-tight electrochemical cell, the authors can perform high-temperature coulometric titration and measure electronic transport properties to determine the electronic defect structure of metal oxides. This technique reduces the time and expense required for conventional thermogravimetric measurements. The components of the gas-tight coulometric titration cell are an oxygen sensor, Pt\\/yttria stabilized zirconia (YSZ)\\/Pt, and an encapsulated metal oxide

  3. Analysis of secondary lithium cells with sulfur dioxide based electrolytes

    Microsoft Academic Search

    Robert C. McDonald; Peter Harris; Sohrab Hossain; Franz Goebel

    1992-01-01

    Recent developments in lithium rechargeable cells using liquid SO 2-based electrolyte have led to the demonstration of 100-200 cycles at practical energy densities of over 100 Wh\\/kg in flat-plate cells. Analytical studies were conducted to confirm the discharge mechanism and to explore the effects of using various cycling voltage limits in Li\\/CuCl2 cells. These cells have excellent shelf-life potential and

  4. Neutrophils and monocytes transport tumor cell antigens from the peritoneal cavity to secondary lymphoid tissues

    SciTech Connect

    Terasawa, Masao; Nagata, Kisaburo [Division of Molecular Medicine, Department of Biomolecular Science, Faculty of Science, Toho University, 2-2-1, Miyama, Funabashi (Japan); Kobayashi, Yoshiro [Division of Molecular Medicine, Department of Biomolecular Science, Faculty of Science, Toho University, 2-2-1, Miyama, Funabashi (Japan)], E-mail: yoshiro@biomol.sci.toho-u.ac.jp

    2008-12-12

    Antigen-transporting cells take up pathogens, and then migrate from sites of inflammation to secondary lymphoid tissues to induce an immune response. Among antigen-transporting cells, dendritic cells (DCs) are believed to be the most potent and professional antigen-presenting cells that can stimulate naive T cells. However, the cells that transport antigens, tumor cell antigens in particular, have not been clearly identified. In this study we have analyzed what types of cells transport tumor cell antigens to secondary lymphoid tissues. We show that neutrophils, monocytes and macrophages but not DCs engulf X-irradiated P388 leukemic cells after their injection into the peritoneal cavity, and that neutrophils and monocytes but not macrophages migrate to the parathymic lymph nodes (pLN), the blood, and then the spleen. The monocytes in the pLN comprise Gr-1{sup -} and Gr-1{sup +} ones, and some of these cells express CD11c. Overall, this study demonstrates that neutrophils and monocytes transport tumor cell antigens from the peritoneal cavity to secondary lymphoid tissues.

  5. A combined electrochemical and optical trapping platform for measuring single cell respiration rates at electrode interfaces.

    PubMed

    Gross, Benjamin J; El-Naggar, Mohamed Y

    2015-06-01

    Metal-reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. This process is one of the earliest forms of respiration on earth and has significant environmental and technological implications. By performing electron transfer to electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. Understanding such a complex biotic-abiotic interaction necessitates the development of tools capable of probing extracellular electron transfer down to the level of single cells. Here, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect the respiration current correlated with cell-electrode contact. We demonstrate the system with single cell measurements of the dissimilatory-metal reducing bacterium Shewanella oneidensis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer-membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. In addition to the application for extracellular electron transfer studies, the ability to electronically measure cell-specific respiration rates may provide answers for a variety of fundamental microbial physiology questions. PMID:26133851

  6. A combined electrochemical and optical trapping platform for measuring single cell respiration rates at electrode interfaces

    NASA Astrophysics Data System (ADS)

    Gross, Benjamin J.; El-Naggar, Mohamed Y.

    2015-06-01

    Metal-reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. This process is one of the earliest forms of respiration on earth and has significant environmental and technological implications. By performing electron transfer to electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. Understanding such a complex biotic-abiotic interaction necessitates the development of tools capable of probing extracellular electron transfer down to the level of single cells. Here, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect the respiration current correlated with cell-electrode contact. We demonstrate the system with single cell measurements of the dissimilatory-metal reducing bacterium Shewanella oneidensis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer-membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. In addition to the application for extracellular electron transfer studies, the ability to electronically measure cell-specific respiration rates may provide answers for a variety of fundamental microbial physiology questions.

  7. Effects of Operating Conditions on Internal Resistances in Enzyme Fuel Cells Studied via Electrochemical Impedance Spectroscopy

    SciTech Connect

    Aaron, D [Georgia Institute of Technology; Borole, Abhijeet P [ORNL; Yiacoumi, Sotira [Georgia Institute of Technology; Tsouris, Costas [ORNL

    2012-01-01

    Enzyme fuel cells (EFCs) offer some advantages over traditional precious-metal-catalyzed fuel cells, such as polymer electrolyte membrane fuel cells (PEMFCs). However, EFCs exhibit far less power output than PEMFCs and have relatively short life spans before materials must be replaced. In this work, electrochemical impedance spectroscopy (EIS) is used to analyze the internal resistances throughout the EFC at a variety of operating conditions. EIS analysis is focused primarily on the resistances of the anode, solution/membrane, and cathode. Increased enzyme loading results in improved power output and reductions in internal resistance. Conditions are identified for which enzyme loading does not limit the EFC performance. EIS experiments are also reported for EFCs operated continuously for 2 days; power output declines sharply over time, while all internal resistances increase. Drying of the cathode and enzyme/mediator degradation are believed to have contributed to this behavior. Finally, experiments are performed at varying air-humidification temperatures. Little effect on internal resistances or power output is observed. However, it is anticipated that increased air humidification can improve longevity by delivering more water to the cathode. Improvements to the enzymatic cathode are needed for EFC development. These improvements need to focus on improving transport rather than increasing enzyme loading.

  8. Electrochemical based detection of microRNA, mir21 in breast cancer cells.

    PubMed

    Kilic, Tugba; Topkaya, Seda Nur; Ozkan Ariksoysal, Dilsat; Ozsoz, Mehmet; Ballar, Petek; Erac, Yasemin; Gozen, Oguz

    2012-01-01

    In this work, a novel electrochemical microRNA (miRNA) detection method based on enzyme amplified biosensing of mir21 from cell lysate of total RNA was demonstrated. The proposed enzymatic detection method was detailed and compared with the conventional guanine oxidation based assay in terms of detection limit and specificity. For the detection of mir21, capture probes and/or cell lysates were covalently attached onto the pencil graphite electrode (PGE) by coupling agents of N-(dimethylamino)propyl-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysulfosuccinimide (NHS). Having immobilized the capture probe onto the surface of PGE, hybridization was achieved with a biotinylated (from its 3' end) complementary target. Extravidin labeled alkaline phosphatase (Ex-Ap) binds to the biotinylated target due to the interaction between biotin-avidin and the enzyme converts electro-inactive alpha naphtyl phosphate (the substrate) to electro-active alpha naphtol (?-NAP, the product). ?-NAP was oxidized at +0.23 V vs Ag/AgCl and this signal was measured by Differential Pulse Voltammetry (DPV). The signals obtained from ?-NAP oxidation were compared for the probe and hybrid DNA. The specificity of the designed biosensor was proved by using non-complementary sequences instead of complementary sequences and the detection limit of the assay was calculated to be 6 pmol for cell lysates. PMID:22776181

  9. Electrochemical properties of aryladamantanes as new overcharge protection compounds for lithium cells

    NASA Astrophysics Data System (ADS)

    Watanabe, Yuu; Morimoto, Hideyuki; Tobishima, Shin-ichi

    The development of new overcharge protection compounds for 4 V-class lithium cells with LiCoO 2 cathodes was attempted in order to protect the cells from the hazards of ignition and/or explosion when overcharged. At least two requirements must be met as regards overcharge protection compounds. They must have an oxidation potential ( Eox) in the 4.6-4.8 V range versus Li/Li + and they must not adversely influence the lithium cycling efficiency (Eff). The overcharge protection compounds were used by adding them to the electrolyte solution, which was LiClO 4/propylene carbonate. First, this study involved a basic examination of the relationships among the Eox values of arenes including polyacenes, naphthalene derivatives and methylbenzenes, their chemical structure, the aromatic ring size and the effects of substituent functional groups. Next, the Eox and Eff values of cycloalkanes including cyclohexane, decaline, adamantane and norbornane were examined. Based on these examination results, various adamantane derivatives were synthesized and their electrochemical properties were investigated. Finally, four aryladamantanes (1-( p-tolyl)adamantane, 1-( m-tolyl)adamantane, 1-( o-tolyl)adamantane, 1-(4-ethylphenyl)adamantane) were found to exhibit better Eox and Eff values than those of biphenyl, which is already used in commercial cells as an overcharge protection additive.

  10. Microbial Communities and Electrochemical Performance of Titanium-Based Anodic Electrodes in a Microbial Fuel Cell?

    PubMed Central

    Michaelidou, Urania; ter Heijne, Annemiek; Euverink, Gerrit Jan W.; Hamelers, Hubertus V. M.; Stams, Alfons J. M.; Geelhoed, Jeanine S.

    2011-01-01

    Four types of titanium (Ti)-based electrodes were tested in the same microbial fuel cell (MFC) anodic compartment. Their electrochemical performances and the dominant microbial communities of the electrode biofilms were compared. The electrodes were identical in shape, macroscopic surface area, and core material but differed in either surface coating (Pt- or Ta-coated metal composites) or surface texture (smooth or rough). The MFC was inoculated with electrochemically active, neutrophilic microorganisms that had been enriched in the anodic compartments of acetate-fed MFCs over a period of 4 years. The original inoculum consisted of bioreactor sludge samples amended with Geobacter sulfurreducens strain PCA. Overall, the Pt- and Ta-coated Ti bioanodes (electrode-biofilm association) showed higher current production than the uncoated Ti bioanodes. Analyses of extracted DNA of the anodic liquid and the Pt- and Ta-coated Ti electrode biofilms indicated differences in the dominant bacterial communities. Biofilm formation on the uncoated electrodes was poor and insufficient for further analyses. Bioanode samples from the Pt- and Ta-coated Ti electrodes incubated with Fe(III) and acetate showed several Fe(III)-reducing bacteria, of which selected species were dominant, on the surface of the electrodes. In contrast, nitrate-enriched samples showed less diversity, and the enriched strains were not dominant on the electrode surface. Isolated Fe(III)-reducing strains were phylogenetically related, but not all identical, to Geobacter sulfurreducens strain PCA. Other bacterial species were also detected in the system, such as a Propionicimonas-related species that was dominant in the anodic liquid and Pseudomonas-, Clostridium-, Desulfovibrio-, Azospira-, and Aeromonas-related species. PMID:21131513

  11. Microbial communities and electrochemical performance of titanium-based anodic electrodes in a microbial fuel cell.

    PubMed

    Michaelidou, Urania; ter Heijne, Annemiek; Euverink, Gerrit Jan W; Hamelers, Hubertus V M; Stams, Alfons J M; Geelhoed, Jeanine S

    2011-02-01

    Four types of titanium (Ti)-based electrodes were tested in the same microbial fuel cell (MFC) anodic compartment. Their electrochemical performances and the dominant microbial communities of the electrode biofilms were compared. The electrodes were identical in shape, macroscopic surface area, and core material but differed in either surface coating (Pt- or Ta-coated metal composites) or surface texture (smooth or rough). The MFC was inoculated with electrochemically active, neutrophilic microorganisms that had been enriched in the anodic compartments of acetate-fed MFCs over a period of 4 years. The original inoculum consisted of bioreactor sludge samples amended with Geobacter sulfurreducens strain PCA. Overall, the Pt- and Ta-coated Ti bioanodes (electrode-biofilm association) showed higher current production than the uncoated Ti bioanodes. Analyses of extracted DNA of the anodic liquid and the Pt- and Ta-coated Ti electrode biofilms indicated differences in the dominant bacterial communities. Biofilm formation on the uncoated electrodes was poor and insufficient for further analyses. Bioanode samples from the Pt- and Ta-coated Ti electrodes incubated with Fe(III) and acetate showed several Fe(III)-reducing bacteria, of which selected species were dominant, on the surface of the electrodes. In contrast, nitrate-enriched samples showed less diversity, and the enriched strains were not dominant on the electrode surface. Isolated Fe(III)-reducing strains were phylogenetically related, but not all identical, to Geobacter sulfurreducens strain PCA. Other bacterial species were also detected in the system, such as a Propionicimonas-related species that was dominant in the anodic liquid and Pseudomonas-, Clostridium-, Desulfovibrio-, Azospira-, and Aeromonas-related species. PMID:21131513

  12. Electrochemically intercalated MxC60 thin films in a solid state cell (M = Li, K): Optical and photoelectrochemical characterization

    NASA Astrophysics Data System (ADS)

    Dalchiele, E. A.; Rosolen, J. M.; Decker, F.

    1996-11-01

    Solid-state electrochemical cells have been prepared with C60 vacuum-evaporated thin films, a Li- or K-source counter electrode and a polymer PEO-LiClO4 (PEO-KClO4) electrolyte. The electrochemical intercalation in C60 of Li+ (or K+) ions has been performed under constant current conditions up to a formal stoichiometry of the fulleride film equal to Li12C60 (K5C60). A complete charge-transfer pocess from the intercalated alkali to the alkali-metal compound has been assumed. Several quasi-equilibrium potential plateaux were observed during intercalation, that we associate with the coexistence of phases with different intercalant concentration. The electrochemical intercalation process is irreversible to a large extent. Optical and photoelectrochemical spectroscopy of the fulleride films was done “in-situ” at different moments of the intercalation reaction by illuminating the film electrodes through the transparent and conducting glass substrates. The photo electrochemical spectral response agrees well with the optical absorption spectra, both indicating a bandgap of 2.2 eV. The photoelectrochemical response shows a minimum for x = 3 (in the KxC60 compound) and a maximum at x = 4 (in both KxC60 andLixC60 compounds), in agreement with previous conductivity results. NIR diffuse reflectance spectra of the solid-state cell show absorption bands in the fulleride films at a wavelength of 1100 nm. A band-energy diagram has been proposed for the MxC60/PEO-MClO4/M electrochemical cell.

  13. Dynamic Functional Modulation of CD4+ T Cell Recall Responses Is Dependent on the Inflammatory Environment of the Secondary Stimulus

    PubMed Central

    Williams, Matthew A.

    2014-01-01

    The parameters that modulate the functional capacity of secondary Th1 effector cells are poorly understood. In this study, we employ a serial adoptive transfer model system to show that the functional differentiation and secondary memory potential of secondary CD4+ effector T cells are dependent on the inflammatory environment of the secondary challenge. Adoptive transfer of TCR transgenic lymphocytic choriomeningitis virus (LCMV) Glycoprotein-specific SMARTA memory cells into LCMV-immune hosts, followed by secondary challenge with Listeria monocytogenes recombinantly expressing a portion of the LCMV Glycoprotein (Lm-gp61), resulted in the rapid emergence of SMARTA secondary effector cells with heightened functional avidity (as measured by their ability to make IFN? in response to ex vivo restimulation with decreasing concentrations of peptide), limited contraction after pathogen clearance and stable maintenance secondary memory T cell populations. In contrast, transfer of SMARTA memory cells into naïve hosts prior to secondary Lm-gp61 challenge, which resulted in a more extended infectious period, resulted in poor functional avidity, increased death during the contraction phase and poor maintenance of secondary memory T cell populations. The modulation of functional avidity during the secondary Th1 response was independent of differences in antigen load or persistence. Instead, the inflammatory environment strongly influenced the function of the secondary Th1 response, as inhibition of IL-12 or IFN-I activity respectively reduced or increased the functional avidity of secondary SMARTA effector cells following rechallenge in a naïve secondary hosts. Our findings demonstrate that secondary effector T cells exhibit inflammation-dependent differences in functional avidity and memory potential, and have direct bearing on the design of strategies aimed at boosting memory T cell responses. PMID:24854337

  14. Dynamic functional modulation of CD4+ T cell recall responses is dependent on the inflammatory environment of the secondary stimulus.

    PubMed

    Kim, Chulwoo; Jay, David C; Williams, Matthew A

    2014-05-01

    The parameters that modulate the functional capacity of secondary Th1 effector cells are poorly understood. In this study, we employ a serial adoptive transfer model system to show that the functional differentiation and secondary memory potential of secondary CD4+ effector T cells are dependent on the inflammatory environment of the secondary challenge. Adoptive transfer of TCR transgenic lymphocytic choriomeningitis virus (LCMV) Glycoprotein-specific SMARTA memory cells into LCMV-immune hosts, followed by secondary challenge with Listeria monocytogenes recombinantly expressing a portion of the LCMV Glycoprotein (Lm-gp61), resulted in the rapid emergence of SMARTA secondary effector cells with heightened functional avidity (as measured by their ability to make IFN? in response to ex vivo restimulation with decreasing concentrations of peptide), limited contraction after pathogen clearance and stable maintenance secondary memory T cell populations. In contrast, transfer of SMARTA memory cells into naïve hosts prior to secondary Lm-gp61 challenge, which resulted in a more extended infectious period, resulted in poor functional avidity, increased death during the contraction phase and poor maintenance of secondary memory T cell populations. The modulation of functional avidity during the secondary Th1 response was independent of differences in antigen load or persistence. Instead, the inflammatory environment strongly influenced the function of the secondary Th1 response, as inhibition of IL-12 or IFN-I activity respectively reduced or increased the functional avidity of secondary SMARTA effector cells following rechallenge in a naïve secondary hosts. Our findings demonstrate that secondary effector T cells exhibit inflammation-dependent differences in functional avidity and memory potential, and have direct bearing on the design of strategies aimed at boosting memory T cell responses. PMID:24854337

  15. Xyloglucan Endotransglycosylases Have a Function during the Formation of Secondary Cell Walls of Vascular Tissues

    PubMed Central

    Bourquin, Veronica; Nishikubo, Nobuyuki; Abe, Hisashi; Brumer, Harry; Denman, Stuart; Eklund, Marlin; Christiernin, Maria; Teeri, Tunla T.; Sundberg, Björn; Mellerowicz, Ewa J.

    2002-01-01

    Xyloglucan transglycosylases (XETs) have been implicated in many aspects of cell wall biosynthesis, but their function in vascular tissues, in general, and in the formation of secondary walls, in particular, is less well understood. Using an in situ XET activity assay in poplar stems, we have demonstrated XET activity in xylem and phloem fibers at the stage of secondary wall formation. Immunolocalization of fucosylated xylogucan with CCRC-M1 antibodies showed that levels of this species increased at the border between the primary and secondary wall layers at the time of secondary wall deposition. Furthermore, one of the most abundant XET isoforms in secondary vascular tissues (PttXET16A) was cloned and immunolocalized to fibers at the stage of secondary wall formation. Together, these data strongly suggest that XET has a previously unreported role in restructuring primary walls at the time when secondary wall layers are deposited, probably creating and reinforcing the connections between the primary and secondary wall layers. We also observed that xylogucan is incorporated at a high level in the inner layer of nacreous walls of mature sieve tube elements. PMID:12468728

  16. The Impact of a Boosting Immunogen on the Differentiation of Secondary Memory CD8+ T Cells

    Microsoft Academic Search

    Avi-Hai Hovav; Michael W. Panas; Christa E. Osuna; Mark J. Cayabyab; Patrick Autissier; Norman L. Letvin

    2007-01-01

    While recent studies have demonstrated that secondary CD8 T cells develop into effector-memory cells, the impact of particular vaccine regimens on the elicitation of these cells remains poorly defined. In the present study we evaluated the effect of three different immunogens—recombinant vaccinia, recombinant adenovirus, and plasmid DNA—on the generation of memory cellular immune responses. We found that vectors that induce

  17. Non-isothermal electrochemical model for lithium-ion cells with composite cathodes

    NASA Astrophysics Data System (ADS)

    Basu, Suman; Patil, Rajkumar S.; Ramachandran, Sanoop; Hariharan, Krishnan S.; Kolake, Subramanya Mayya; Song, Taewon; Oh, Dukjin; Yeo, Taejung; Doo, Seokgwang

    2015-06-01

    Transition metal oxide cathodes for Li-ion batteries offer high energy density and high voltage. Composites of these materials have shown excellent life expectancy and improved thermal performance. In the present work, a comprehensive non-isothermal electrochemical model for a Lithium ion cell with a composite cathode is developed. The present work builds on lithium concentration-dependent diffusivity and thermal gradient of cathode potential, obtained from experiments. The model validation is performed for a wide range of temperature and discharge rates. Excellent agreement is found for high and room temperature with moderate success at low temperatures, which can be attributed to the low fidelity of material properties at low temperature. Although the cell operation is limited by electronic conductivity of NCA at room temperature, at low temperatures a shift in controlling process is seen, and operation is limited by electrolyte transport. At room temperature, the lithium transport in Cathode appears to be the main source of heat generation with entropic heat as the primary contributor at low discharge rates and ohmic heat at high discharge rates respectively. Improvement in electronic conductivity of the cathode is expected to improve the performance of these composite cathodes and pave way for its wider commercialization.

  18. Computational electrochemical and {sup 7}Li NMR studies of lithiated disordered carbons electrodes in lithium ion cells

    SciTech Connect

    Sandi, G.; Gerald, R.E. II; Scanlon, L.G.; Carrado, K.A.; Winans, R.E.

    1998-07-01

    Disordered carbons that deliver high reversible capacity in electrochemical cells have been synthesized by using inorganic clays as templates to control the pore size and the surface area. The capacities obtained were much higher than those calculated if the resultant carbon had a graphitic-like structure. Computational chemistry was used to investigate the nature of lithium bonding in a carbon lattice unlike graphite. The lithium intercalated fullerene Li{sub 8}-C{sub 60} was used as a model for the (nongraphitic) disordered carbon lattice. A dilithium-C{sub 60} system with a charge and multiplicity of (0,1) and a trilithium-C{sub 60} system with a charge and multiplicity of (0,4) were investigated. The spatial distribution of lithium ions in an electrochemical cell containing this novel disordered carbon material was investigated in situ by Li-7 NMR using an electrochemical cell that was incorporated into a toroid cavity nuclear magnetic resonance (NMR) imager. The concentration of solvated Li{sup +} ions in the carbon anode appears to be larger than in the bulk electrolyte, is substantially lower near the copper/carbon interface, and does not change with cell charging.

  19. Roles of microtubules and cellulose microfibril assembly in the localization of secondary-cell-wall deposition in developing tracheary elements

    Microsoft Academic Search

    A. W. Roberts; A. O. Frost; E. M. Roberts; C. H. Haigler

    2004-01-01

    Summary. The roles of cellulose microfibrils and cortical microtubules in establishing and maintaining the pattern of secondary-cell-wall deposition in tracheary elements were investigated with direct dyes to inhibit cellulose microfibril assembly and amiprophosmethyl to inhibit microtubule polymerization. When direct dyes were added to xylogenic cultures of Zinnia elegans L. mesophyll cells just before the onset of differentiation, the secondary cell

  20. Non-Faradaic electrochemical modification of catalytic activity: the work function of metal electrodes in solid electrolyte cells

    Microsoft Academic Search

    Costas G. Vayenas; Symeon Bebelis; Ioannis V. Yentekakis; Stelios Neophytides

    1992-01-01

    The catalytic activity and selectivity of metal films used as electrodes in solid electrolyte cells can be altered dramatically and reversibly by polarizing the metal-sohd electrolyte interface This effect, termed non-Faradalc electrochemical modification of catalytic act tvaty (NEMCA) leads to steady state catalytic rate increases up to 3 X l 0 s t~mes higher than the steady state rate of

  1. Recombination profiles in poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] light-emitting electrochemical cells

    Microsoft Academic Search

    J. M. Leger; S. A. Carter; B. Ruhstaller

    2005-01-01

    We present a study on the optical and electronic properties of light-emitting electrochemical cells (LECs) based on poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) with the goal of understanding emission profiles and characterizing salt and electrode dependence. Direct imaging of photoluminescence and electroluminescence profiles of planar LECs and simulations of optical interference effects were performed in order to gain insight into emission profiles in vertical

  2. Electrochemical response of zirconia-coated 316L stainless-steel in a simulated proton exchange membrane fuel cell environment

    Microsoft Academic Search

    W. G. Lee; K. H. Cho; S. B. Lee; S. B. Park; H. Jang

    2009-01-01

    The corrosion resistance of zirconia-coated austenitic stainless-steel 316L was investigated in a simulated proton exchange membrane fuel cell (PEMFC) environment. The zirconia coating was performed using a sol–gel dip coating method and electrochemical tests were carried out at 80°C in 1M H2SO4 solution to accelerate corrosion. The results showed that the precursor containing zirconium alkoxide and zirconium acetate hydroxide changed

  3. More accurate macro-models of solid oxide fuel cells through electrochemical and microstructural parameter estimation - Part II: Parameter estimation

    NASA Astrophysics Data System (ADS)

    Boigues-Muñoz, Carlos; Pumiglia, Davide; McPhail, Stephen J.; Santori, Giulio; Montinaro, Dario; Comodi, Gabriele; Carlini, Maurizio; Polonara, Fabio

    2015-07-01

    This paper presents a systematic synergetic approach between experimental measurements, equivalent circuit modelling (described in Part I) and macro-scale modelling theory which has proved to be instrumental for the estimation of microstructural and electrochemical features of a Ni-YSZ|YSZ|Pr2NiO4+? - GDC solid oxide fuel cell (SOFC). The aforementioned parameters have been used to generate a more accurate CFD macro-model which has been validated against the experimental results (presented in Part III).

  4. High-durability titanium bipolar plate modified by electrochemical deposition of platinum for unitized regenerative fuel cell (URFC)

    Microsoft Academic Search

    Ho-Young Jung; Sheng-Yang Huang; Branko N. Popov

    2010-01-01

    The electrochemical deposition of platinum on a titanium bipolar plate (Pt\\/Ti) was studied for applications in a unitized regenerative fuel cell (URFC). Platinum deposition on the titanium plate was carried out in the platinum precursor solution (1.8gdm?3) at constant acidity (pH 1.0) and temperature (90°C). The pre-treatment of the titanium plate and the applied deposition current density were optimized to

  5. Development of electrochemical cells based on (PEO + NaYF4) and (PEO + KYF 4) polymer electrolytes

    Microsoft Academic Search

    S. Sreepathi Rao; M. Jaipal Reddy; E. Laxmi Narsaiah; U. V. Subba Rao

    1995-01-01

    Thin film ion conducting polymer electrolytes based on polyethylene oxide (PEO) complexed with NaYF4 and KYF4 salts have been prepared using the solution-cast technique. The complexation of NaYF4 and KYF4 salts with PEO were confirmed by infra-red and X-ray diffraction studies. The results of the electrical conductivity and transference number measurements in these electrolytes have been reported. Electrochemical cells with

  6. ELECTRON TRANSPORT AND SECONDARY EMISSION IN A SURFACE OF SOLAR CELL P. Degond, R. Talaalout, M.-H. Vignal

    E-print Network

    Vignal, Marie-Hélène

    1 ELECTRON TRANSPORT AND SECONDARY EMISSION IN A SURFACE OF SOLAR CELL P. Degond, R. Talaalout, M in- volving secondary emission and desorption. By establishing a uid model, numerical simulation of a primary discharge where electron secondary emission plays an important role. A schematic of a conventional

  7. Evaluation program for secondary spacecraft cells: Cycle life test

    NASA Technical Reports Server (NTRS)

    Harkness, J. D.

    1979-01-01

    The service life and storage stability for several storage batteries were determined. The batteries included silver-zinc batteries, nickel-cadmium batteries, and silver-cadmium batteries. The cell performance characteristics and limitations are to be used by spacecraft power systems planners and designers. A statistical analysis of the life cycle prediction and cause of failure versus test conditions is presented.

  8. Electrochemical study of lithiated transition metal oxide composite for single layer fuel cell

    NASA Astrophysics Data System (ADS)

    Hu, Huiqing; Lin, Qizhao; Muhammad, Afzal; Zhu, Bin

    2015-07-01

    This study analyzed the effect of various semiconductors of transition metal oxides in modified lithiated NiO on the electrochemical performance of a single layer fuel cell (SLFC). A typical ionic conductor Ce0.8Sm0.2O2-? (SDC) and three types of semiconductors Li0.3Ni0.6Cu0.07Sr0.03O2-? (LNCuS), Li0.3Ni0.6Mn0.07Sr0.03O2-? (LNMnS) and Li0.3Ni0.6Co0.07Sr0.03O2-? (LNCoS), were the fundamental components of the SLFCs. The components were characterized by using X-ray diffraction (XRD), a scanning electron microscope (SEM), and an energy-dispersive X-ray spectrometer (EDS). The stability of the synthesized materials was evaluated using thermal gravity analysis (TGA). The ohmic resistances at 500 °C were 0.36, 0.48 and 0.58 ? cm2 for 6SDC-4LNMnS, 6SDC-4LNCoS and 6SDC-4LNCuS, respectively. Among the three SLFCs, the single cell with 6SDC-4LNMnS achieves the highest power density (422 mW cm-2) but the lowest temperature stability, while the single cell with 6SDC-4LNCuS achieved the lowest power density (331 mW cm-2) but the highest temperature stability during the operation temperature.

  9. Enhancing electrochemical performance by control of transport properties in buffer layers - solid oxide fuel/electrolyser cells.

    PubMed

    Ramasamy, Devaraj; Nasani, Narendar; Brandão, Ana D; Pérez Coll, Domingo; Fagg, Duncan P

    2015-04-21

    The current work demonstrates how tailoring the transport properties of thin ceria-based buffer layers in solid oxide fuel or electrolyser cells can provide the necessary phase stability against chemical interaction at the electrolyte/electrode interface, while also providing radical improvements in the electrochemical performance of the oxygen electrode. Half cells of Ce0.8R0.2O2-? + 2 mol% Co buffer layers (where R = Gd, Pr) with Nd2NiO4+? electrodes were fabricated by spin coating on dense YSZ electrolyte supports. Dramatic decreases in polarization resistance, Rp, of up to an order of magnitude, could be achieved in the order, Pr ? Gd < no buffer layer. The current article shows how this improvement can be related to increased levels of ambipolar conductivity in the mixed conducting buffer layer, which provides an additional parallel path for electrochemical reaction. This is an important breakthrough as it shows how electrode polarization resistance can be substantially improved, in otherwise identical electrochemical cells, solely by tailoring the transport properties of thin intermediate buffer layers. PMID:25857870

  10. Electrochemically initiated tagging of thiols using an electrospray ionization based liquid microjunction surface sampling probe two-electrode cell.

    PubMed

    Van Berkel, Gary J; Kertesz, Vilmos

    2009-05-01

    This paper reports on the conversion of a liquid microjunction surface sampling probe (LMJ-SSP) into a two-electrode electrochemical cell using a conductive sample surface and the probe as the two electrodes with an appropriate battery powered circuit. With this LMJ-SSP, two-electrode cell arrangement, tagging of analyte thiol functionalities (in this case peptide cysteine residues) with hydroquinone tags was initiated electrochemically using a hydroquinone-doped solution when the analyte either was initially in solution or was sampled from a surface. Efficient tagging (approximately 90%), at flow rates of 5-10 microL/min, could be achieved for up to at least two cysteines on a peptide. The high tagging efficiency observed was explained with a simple kinetic model. In general, the incorporation of a two-electrode electrochemical cell, or other multiple electrode arrangement, into the LMJ-SSP is expected to add to the versatility of this approach for surface sampling and ionization coupled with mass spectrometric detection. PMID:19337980

  11. Electrochemically Initiated Tagging of Thiols Using an Electrospray Ionization-Based Liquid Microjunction Surface Sampling Probe Two-Electrode Cell

    SciTech Connect

    Van Berkel, Gary J [ORNL; Kertesz, Vilmos [ORNL

    2009-01-01

    This paper reports on the conversion of a liquid microjunction surface sampling probe (LMJ-SSP) into a two electrode electrochemical cell using a conductive sample surface and the probe as the two electrodes with an appropriate battery powered circuit. With this LMJ-SSP, two-electrode cell arrangement, tagging of analyte thiol functionalities (in this case peptide cysteine residues) with hydroquinone tags was initiated electrochemically using a hydroquinone doped solution when the analyte either was initially in solution or was sampled from a surface. Efficient tagging (~90%), at flow rates of 5-10 L/min, could be achieved for up to at least two cysteines on a peptide. The high tagging efficiency observed was explained with a simple kinetic model. In general, the incorporation of a two-electrode electrochemical cell, or other multiple electrode arrangement, into the LMJ-SSP is expected to add to the versatility of this approach for surface sampling and ionization coupled with mass spectrometric detection.

  12. A microwell device for targeting single cells to electrochemical microelectrodes for high-throughput amperometric detection of quantal exocytosis

    PubMed Central

    Liu, Xin; Barizuddin, Syed; Shin, Wonchul; Mathai, Cherian J.; Gangopadhyay, Shubhra; Gillis, Kevin D.

    2011-01-01

    Electrochemical microelectrodes are commonly used to detect spikes of amperometric current that correspond to exocytosis of oxidizable transmitter from individual vesicles, i.e., quantal exocytosis. We are developing transparent multi- electrochemical electrode arrays on microchips in order to automate measurement of quantal exocytosis. Here we report development of an improved device to target individual cells to each microelectrode in an array. Efficient targeting (~75%) is achieved using cell-sized micro-well traps fabricated in SU-8 photoresist together with patterning of poly (L-lysine) in register with electrodes to promote cell adhesion. The surface between electrodes is made resistant to cell adhesion using poly (ethylene glycol) in order to facilitate movement of cells to electrode “docking sites”. We demonstrate the activity of the electrodes using the test analyte ferricyanide and perform recordings of quantal exocytosis from bovine adrenal chromaffin cells on the device. Multiple cell recordings on a single device demonstrate the consistency of spike measurements and multiple recordings from the same electrodes demonstrate that the device can be cleaned and reused without degradation of performance. The new device will enable high-throughput studies of quantal exocytosis and may also find application in rapidly screening drugs or toxins for effects on exocytosis. PMID:21355543

  13. Secondary metabolite localization by autofluorescence in living plant cells.

    PubMed

    Talamond, Pascale; Verdeil, Jean-Luc; Conéjéro, Geneviève

    2015-01-01

    Autofluorescent molecules are abundant in plant cells and spectral images offer means for analyzing their spectra, yielding information on their accumulation and function. Based on their fluorescence characteristics, an imaging approach using multiphoton microscopy was designed to assess localization of the endogenous fluorophores in living plant cells. This method, which requires no previous treatment, provides an effective experimental tool for discriminating between multiple naturally-occurring fluorophores in living-tissues. Combined with advanced Linear Unmixing, the spectral analysis extends the possibilities and enables the simultaneous detection of fluorescent molecules reliably separating overlapping emission spectra. However, as with any technology, the possibility for artifactual results does exist. This methodological article presents an overview of the applications of tissular and intra-cellular localization of these intrinsic fluorophores in leaves and fruits (here for coffee and vanilla). This method will provide new opportunities for studying cellular environments and the behavior of endogenous fluorophores in the intracellular environment. PMID:25808147

  14. Relation between primary and secondary metabolism in plant cell suspensions

    Microsoft Academic Search

    Linus H. W. Plas; Conny Eijkelboom; Marc J. M. Hagendoorn

    1995-01-01

    Cell suspensions ofMorinda citrifolia are able to produce large amounts of anthraquinones (AQ) when they are cultivated on a B5-medium containing 1 mg 1-1 naphtyl acetic acid (NAA); this production is inhibited by addition of 2,4-dichloro-phenoxyacetic acid (2,4-d). Also during cultivation on 1 mg 1-1 2,4-d AQ-production is absent.

  15. Method of bonding a conductive layer on an electrode of an electrochemical cell

    DOEpatents

    Bowker, J.C.; Singh, P.

    1989-08-29

    A dense, electronically conductive interconnection layer is bonded onto a porous, tubular, electronically conductive air electrode structure, optionally supported by a ceramic support, by (A) providing an air electrode surface, (B) forming on a selected portion of the electrode surface, without the use of pressure, particles of LaCrO[sub 3] doped with an element selected from the group consisting of Sr, Mg, Ca, Ba, Co, and mixtures thereof, where the particles have a deposit on their surface comprising calcium oxide and chromium oxide; (C) heating the particles with the oxide surface deposit in an oxidizing atmosphere at from 1,300 C to 1,550 C, without the application of pressure, to provide a dense, sintered, interconnection material bonded to the air electrode, where calcium and chromium from the surface deposit are incorporated into the structure of the LaCrO[sub 3]. A solid electrolyte layer can be applied to the uncovered portion of the air electrode, and a fuel electrode can be applied to the solid electrolyte, to provide an electrochemical cell. 4 figs.

  16. White light-emitting electrochemical cells based on the Langmuir-Blodgett technique.

    PubMed

    Fernández-Hernández, Jesús M; De Cola, Luisa; Bolink, Henk J; Clemente-León, Miguel; Coronado, Eugenio; Forment-Aliaga, Alicia; López-Muñoz, Angel; Repetto, Diego

    2014-11-25

    Light-emitting electrochemical cells (LECs) showing a white emission have been prepared with Langmuir-Blodgett (LB) films of the metallosurfactant bis[2-(2,4-difluorophenyl)pyridine][2-(1-hexadecyl-1H-1,2,3-triazol-4-yl)pyridine]iridium(III) chloride (1), which work with an air-stable Al electrode. They were prepared by depositing a LB film of 1 on top of a layer of poly(N,N'-diphenyl-N,N'-bis(4-hexylphenyl)-[1,1'-biphenyl]-4,4'-diamine (pTPD) spin-coated on indium tin oxide (ITO). The white color of the electroluminescence of the device contrasts with the blue color of the photoluminescence of 1 in solution and within the LB films. Furthermore, the crystal structure of 1 is reported together with the preparation and characterization of the Langmuir monolayers (?-A compression isotherms and Brewster angle microscopy (BAM)) and LB films of 1 (IR, UV-vis and emission spectroscopy, X-ray photoelectron spectroscopy (XPS), specular X-ray reflectivity (SXR), and atomic force microscopy (AFM)). PMID:25347390

  17. Electrochemical Characteristics of Tin Oxide-Graphite as Anode Material for Lithium-ion Cells

    NASA Astrophysics Data System (ADS)

    Hasanaly, Siti Munirah

    2010-03-01

    Tin oxide anode materials used in lithium-ion cells experience large volume changes during charging and discharging which cause substantial losses in capacity. In this work, the tin oxide-graphite composite is proposed as an alternative anode material to overcome this problem. The composite was synthesised from a solution of tin chloride dihydrate and graphite powders with citric acid as the chelating agent. In this sol-gel method, a solid phase is formed through a chemical reaction in a liquid phase at moderate temperature. The technique offers several advantages compared to the solid state synthesis technique such as the ability to maintain the homogeneous mixture of precursors during synthesis and to produce small particles. The electrochemical behaviour of the anode material was investigated by means of galvanostatic charge discharge technique. An initial reversible capacity of 748 mAh/g is obtained and nearly 600 mAh/g was retained upon the reaching the fifth cycle. This study shows that the presence of graphite is able to minimise the agglomeration of tin particles that causes large volume changes during cycling, thereby improving cyclability of the anode material.

  18. Electrochemical performance of microbial fuel cells based on disulfonated poly(arylene ether sulfone) membranes

    NASA Astrophysics Data System (ADS)

    Choi, Tae Hwan; Won, Young-Bin; Lee, Jin-Won; Shin, Dong Won; Lee, Young Moo; Kim, Minkyong; Park, Ho Bum

    2012-12-01

    A microbial fuel cell (MFC) is a bio-electrochemical system that drives a current by mimicking bacterial interactions found in nature. Usually, MFCs use Nafion as a PEM to separate the electrodes while permitting protons transfer between the anode and cathode. However, Nafion is expensive and accounts for a large percentage of the costs in MFC configuration. Here, we show MFCs using hydrocarbon-based PEM, disulfonated poly (arylene ether sulfone) (BPSH), which is considered as one of alternative PEM, and relatively inexpensive as compared with Nafion. BPSH membranes exhibit a comparable performance to Nafion 212. Especially, BPSH 40 and 60 (mole %) have higher proton conductivity than Nafion 212. In a two-chamber system, MFC with BPSH 40 shows higher voltage than that with Nafion 212. MFCs with BPSH 20 and 30 show lower voltage decline than other PEMs. In a single-chamber system, a voltage of MFC with BPSH 40 shows about 30% higher (17 mV) than that with Nafion 212 (13 mV) with internal resistance of 10 ?. In addition, The MFC with BPSH 40 produced about 10% higher maximum power density (126 mW m-2) than that with Nafion 212 (111 mW m-2).

  19. The toughness of secondary cell wall and woody tissue

    PubMed Central

    Lucas, P. W.; Tan, H. T. W.; Cheng, P. Y.

    1997-01-01

    The 'across grain' toughness of 51 woods has been determined on thin wet sections using scissors. The moisture content of sections and the varying sharpness of the scissor blades had little effect on the results. In thin sections (less than 0.6mm), toughness rose linearly with section thickness. The intercept toughness at zero thickness, estimated from regression analysis, was proportional to relative density, consistent with values reported for non-woody plant tissues. Extrapolation of the intercept toughness of these woods and other plant tissues/materials to a relative density of 1.0 predicted a toughness of 3.45kJ m-2 , which we identify with the intrinsic toughness of the cell wall. This quantity appears to predict published results from KIC tests on woods and is related to the propensity for crack deflection. The slope of the relationship between section thickness and toughness, describing the work of plastic buckling of cells, was not proportional to relative density, the lightest (balsa) and heaviest (lignum vitae) woods fracturing with less plastic work than predicted. The size of the plastic zone around the crack tip was estimated to be 0.5mm in size. From this, the hypothetical overall toughness of a thick (greater than 1 mm) block of solid cell wall material was calculated as 39.35 kJ m-2, due to both cell wall resistance (10 per cent) and the plastic buckling of cells (90 per cent). This value successfully predicts the toughness of most commercial woods (of relative densities between 0.2 and 0.8) from 'work area' tests in tension and bending. Though density was the most important factor, both fibre width/fibre length (in hardwoods) and lignin/cellulose ratios were negatively correlated with the work of plastic buckling, after correcting for density. At low densities the work of plastic buckling in the longitudinal radial (LR) direction exceeded that in longitudinal tangential (LT), but the reverse was true for relative densities above 0.25. This could be attributed to the direction of rays. Density for density, the toughness of temperate hardwoods tested was about 20 per cent lower than that of tropical hardwoods. This is probably due to the much greater number of vessels in temperate hardwoods. Vessels appear either not to display buckling behaviour during fracture at all or to collapse cheaply. These general results have applications to other plant tissues.

  20. Stromal and hematopoietic cells in secondary lymphoid organs: partners in immunity

    PubMed Central

    Malhotra, Deepali; Fletcher, Anne L.; Turley, Shannon J.

    2012-01-01

    Summary Secondary lymphoid organs (SLOs), including lymph nodes, Peyer's patches, and the spleen, have evolved to bring cells of the immune system together. In these collaborative environments, lymphocytes scan the surfaces of antigen-presenting cells for cognate antigens, while moving along stromal networks. The cell-cell interactions between stromal and hematopoietic cells in SLOs are therefore integral to the normal functioning of these tissues. Not only do stromal cells physically construct SLO architecture, but they are essential for regulating hematopoietic populations within these domains. Stromal cells interact closely with lymphocytes and dendritic cells, providing scaffolds on which these cells migrate, and recruiting them into niches by secreting chemokines. Within lymph nodes, stromal cell-ensheathed conduit networks transport small antigens deep into the SLO parenchyma. More recently, stromal cells have been found to induce peripheral CD8+ T-cell tolerance and control the extent to which newly activated T cells proliferate within lymph nodes. Thus, stromal-hematopoietic crosstalk has important consequences for regulating immune cell function within SLOs. In addition, stromal cell interactions with hematopoietic cells, other stroma, and the inflammatory milieu have profound effects on key stromal functions. Here, we examine ways in which these interactions within the lymph node environment influence the adaptive immune response. PMID:23278748

  1. A scanning electron microscopic study of secondary lamellae and chloride cells of rainbow trout ( Salmo gairdneri )

    Microsoft Academic Search

    Kenneth R. Olson; Paul O. Fromm

    1973-01-01

    Scanning electron micrographs of gill tissue from rainbow trout fixed with 50% glutaraldehyde revealed the presence of microridges on surfaces of epithelial cells of the secondary lamellae. These microridges vary in length from 1 to 7 µ, with a mean height of 0.75 µ. Calculations show that they increase the total lamellar epithelial surface area approximately 2.5 fold. Mucus secreting

  2. Graviresponsiveness and columella cell structure in primary and secondary roots of Ricinus communis

    Microsoft Academic Search

    Randy Moore; John Pasieniuk

    1984-01-01

    In order to determine what structural changes are associated with the onset of graviresponsiveness by plant roots, we have monitored the quantitative ultrastructures of columella (i.e., graviperceptive) cells in primary and secondary roots of Ricinus communis. The relative volumes of cellular components in lateral (i.e., minimally graviresponsive) roots were not significantly different from those of primary roots. The relative volumes

  3. The overall structure of the human lens is one of succes-sive generations of secondary fiber cells stratified chrono-

    E-print Network

    Hammock, Bruce D.

    The overall structure of the human lens is one of succes- sive generations of secondary fiber cells specialized fiber cells located at the core (nucleus) of the lens undergo pseudo-apoptosis to become devoid

  4. A wound-type lithium/polyaniline secondary cell

    NASA Astrophysics Data System (ADS)

    Li, Changzhi; Zhang, Borong; Wang, Baochen

    1992-07-01

    A wound-type cell with a polyaniline (PAn) positive electrode, a LiClON4-propylene carbonate (PC) electrolyte, and a lithium-foil negative electrode is constructed. The two electrodes are separated by a polypropylene separator. The PAn is deposited on carbon felt from a HClON4 solution containing aniline by galvanostatic or potentiostatic electrolysis. Using cyclic voltammetry charge/discharge cycles and charge/retention tests, the following results are obtained: (1) reversibility of the charge/discharge reaction of the PAn electrode is very good; (2) more than 50 charge/discharge cycles at 80 percent charge/discharge efficiency and 260 W h/kg discharge energy density can be achieved at 50 mA between 2 and 4 V; (3) the open-circuit voltage and the capacity retention of the battery after storage at open-circuit for 60 days are 3.4 V and 33 percent, respectively.

  5. Permeabilization of cultivated plant cells by electroporation for release of intracellularly stored secondary products.

    PubMed

    Brodelius, P E; Funk, C; Shillito, R D

    1988-05-01

    Plant cell suspension cultures producing secondary metabolites have been permeabilized for product release by electroporation. The two cell cultures studied, i.e. Thalictrum rugosum and Chenopodium rubrum, require about 5 and 10 kV cm(-1), respectively, for complete permeabilization (release of all the intracellularly stored product). The number of electrical pulses and capacitance used had a relatively limited effect on product release while the viability of the cells was strongly influenced by the latter. Conditions for complete product release resulted in total loss of viability of the cells after treatment. The release of product from immobilized cells was also achieved by electroporation. Cells entrapped in alginate required less voltage for permeabilization than free or agarose entrapped cells. PMID:24241595

  6. Regeneration of anion exchange resins by catalyzed electrochemical reduction

    DOEpatents

    Gu, Baohua (Oak Ridge, TN); Brown, Gilbert M. (Knoxville, TN)

    2002-01-01

    Anion exchange resins sorbed with perchlorate may be regenerated by a combination of chemical reduction of perchlorate to chloride using a reducing agent and an electrochemical reduction of the oxidized reducing agent. Transitional metals including Ti, Re, and V are preferred chemical reagents for the reduction of perchlorate to chloride. Complexing agents such as oxalate are used to prevent the precipitation of the oxidized Ti(IV) species, and ethyl alcohol may be added to accelerate the reduction kinetics of perchlorate. The regeneration may be performed by continuously recycling the regenerating solution through the resin bed and an electrochemical cell so that the secondary waste generation is minimized.

  7. Apoptotic cells subjected to cold/warming exposure disorganize apoptotic microtubule network and undergo secondary necrosis.

    PubMed

    Oropesa-Ávila, Manuel; Fernández-Vega, Alejandro; de la Mata, Mario; Garrido-Maraver, Juan; Cotán, David; Paz, Marina Villanueva; Pavón, Ana Delgado; Cordero, Mario D; Alcocer-Gómez, Elizabet; de Lavera, Isabel; Lema, Rafael; Zaderenko, Ana Paula; Sánchez-Alcázar, José A

    2014-09-01

    Apoptotic microtubule network (AMN) is organized during apoptosis, forming a cortical structure beneath the plasma membrane which plays a critical role in preserving cell morphology and plasma membrane integrity. The aim of this study was to examine the effect of cold/warming exposure on apoptotic microtubules and plasma membrane integrity during the execution phase of apoptosis. We demonstrated in camptothecin-induced apoptotic H460 cells that cold/warming exposure disorganized apoptotic microtubules and allowed the access of active caspases to the cellular cortex and the cleavage of essential proteins in the preservation of plasma membrane permeability. Cleavage of cellular cortex and plasma membrane proteins, such as ?-spectrin, paxilin, focal adhesion kinase and calcium ATPase pump (PMCA-4) involved in cell calcium extrusion resulted in increased plasma permeability and calcium overload leading apoptotic cells to secondary necrosis. The essential role of caspase-mediated cleavage in this process was demonstrated because the addition of the pan-caspase inhibitor z-VAD during cold/warming exposure that induces AMN depolymerization avoided the cleavage of cortical and plasma membrane proteins and prevented apoptotic cells to undergo secondary necrosis. Likewise, apoptotic microtubules stabilization by taxol during cold/warming exposure also prevented cellular cortex and plasma membrane protein cleavage and secondary necrosis. Furthermore, microtubules stabilization or caspase inhibition during cold/warming exposure was also critical for proper phosphatidylserine externalization and apoptotic cell clearance by macrophages. These results indicate that cold/warming exposure of apoptotic cells induces secondary necrosis which can be prevented by both, microtubule stabilization or caspase inhibition. PMID:25027509

  8. Characterization of high-power lithium-ion cells during constant current cycling. Part I. Cycle performance and electrochemical diagnostics

    SciTech Connect

    Shim, Joongpyo; Striebel, Kathryn A.

    2003-01-24

    Twelve-cm{sup 2} pouch type lithium-ion cells were assembled with graphite anodes, LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} cathodes and 1M LiPF{sub 6}/EC/DEC electrolyte. These pouch cells were cycled at different depths of discharge (100 percent and 70 percent DOD) at room temperature to investigate cycle performance and pulse power capability. The capacity loss and power fade of the cells cycled over 100 percent DOD was significantly faster than the cell cycled over 70 percent DOD. The overall cell impedance increased with cycling, although the ohmic resistance from the electrolyte was almost constant. From electrochemical analysis of each electrode after cycling, structural and/or impedance changes in the cathode are responsible for most of the capacity and power fade, not the consumption of cycleable Li from side-reactions.

  9. Cell differentiation, secondary cell-wall formation and transformation of callus tissue of Pinus radiata D. Don

    Microsoft Academic Search

    Ralf Möller; Armando G. McDonald; Christian Walter; Philip J. Harris

    2003-01-01

    Tracheid and sclereid differentiation was induced in callus cultures of Pinus radiata D. Don by culturing on a basal medium containing activated charcoal but no phytohormones; sclereids differentiated in callus derived from xylem strips, but not in callus derived from hypocotyl segments. The tracheids differentiated in hypocotyl-derived callus had helical, scalariform, reticulated or pitted secondary cell-wall patterns, but those differentiated

  10. An electrochemical cell for in operando studies of lithium/sodium batteries using a conventional x-ray powder diffractometer

    SciTech Connect

    Shen, Yanbin; Pedersen, Erik E.; Christensen, Mogens; Iversen, Bo B., E-mail: bo@chem.au.dk [Center for Materials Crystallography, Department of Chemistry and iNANO, Aarhus University, Aarhus (Denmark)

    2014-10-15

    An electrochemical cell has been designed for powder X-ray diffraction studies of lithium ion batteries (LIB) and sodium ion batteries (SIB) in operando with high time resolution using a conventional powder X-ray diffractometer. The cell allows for studies of both anode and cathode electrode materials in reflection mode. The cell design closely mimics that of standard battery testing coin cells and allows obtaining powder X-ray diffraction patterns under representative electrochemical conditions. In addition, the cell uses graphite as the X-ray window instead of beryllium, and it is easy to operate and maintain. Test examples on lithium insertion/extraction in two spinel-type LIB electrode materials (Li{sub 4}Ti{sub 5}O{sub 12} anode and LiMn{sub 2}O{sub 4} cathode) are presented as well as first results on sodium extraction from a layered SIB cathode material (Na{sub 0.84}Fe{sub 0.56}Mn{sub 0.44}O{sub 2})

  11. Liquid metal electrodes in secondary batteries. [Review of developments in batteries of various types

    Microsoft Academic Search

    Steunenberg

    1976-01-01

    Among the liquid metals that might be considered for use as electrode materials in high-performance secondary (electrically rechargeable) batteries, lithium and sodium show the greatest promise because of their low equivalent weight, electronegativity, resistivity, and polarization. Much of the early work on molten alkali metals in electrochemical cells was directed toward the development of thermally regenerative cells for the direct

  12. Novel Management of Acute or Secondary Biliary Liver Conditions Using Hepatically Differentiated Human Dental Pulp Cells

    PubMed Central

    Ishkitiev, Nikolay; Imai, Toshio; Tanaka, Tomoko; Fushimi, Naho; Mitev, Vanyo; Okada, Mio; Tominaga, Noriko; Ono, Sachie; Ishikawa, Hiroshi

    2015-01-01

    The current definitive treatment for acute or chronic liver condition, that is, cirrhosis, is liver transplantation from a limited number of donors, which might cause complications after donation. Hence, bone marrow stem cell transplantation has been developed, but the risk of carcinogenesis remains. We have recently developed a protocol for hepatic differentiation of CD117+ stem cells from human exfoliated deciduous teeth (SHED). In the present study, we examine whether SHED hepatically differentiated (hd) in vitro could be used to treat acute liver injury (ALI) and secondary biliary cirrhosis. The CD117+ cell fraction was magnetically separated from SHED and then differentiated into hepatocyte-like cells in vitro. The cells were transplanted into rats with either ALI or induced secondary biliary cirrhosis. Engraftment of human liver cells was determined immunohistochemically and by in situ hybridization. Recovery of liver function was examined by means of histochemical and serological tests. Livers of transplanted animals were strongly positive for human immunohistochemical factors, and in situ hybridization confirmed engraftment of human hepatocytes. The tests for recovery of liver function confirmed the presence of human hepatic markers in the animals' blood serum and lack of fibrosis and functional integration of transplanted human cells into livers. No evidence of malignancy was found. We show that in vitro hdSHED engraft morphologically and functionally into the livers of rats having acute injury or secondary biliary cirrhosis. SHED are readily accessible adult stem cells, capable of proliferating in large numbers before differentiating in vitro. This makes SHED an appropriate and safe stem cell source for regenerative medicine. PMID:25234861

  13. Viral particles drive rapid differentiation of memory B cells into secondary plasma cells producing increased levels of antibodies.

    PubMed

    Zabel, Franziska; Mohanan, Deepa; Bessa, Juliana; Link, Alexander; Fettelschoss, Antonia; Saudan, Philippe; Kündig, Thomas M; Bachmann, Martin F

    2014-06-15

    Extensive studies have been undertaken to describe naive B cells differentiating into memory B cells at a cellular and molecular level. However, relatively little is known about the fate of memory B cells upon Ag re-encounter. We have previously established a system based on virus-like particles (VLPs), which allows tracking of VLP-specific B cells by flow cytometry as well as histology. Using allotype markers, it is possible to adoptively transfer memory B cells into a naive mouse and track responses of naive and memory B cells in the same mouse under physiological conditions. We have observed that VLP-specific memory B cells quickly differentiated into plasma cells that drove the early onset of a strong humoral IgG response. However, neither IgM(+) nor IgG(+) memory B cells proliferated extensively or entered germinal centers. Remarkably, plasma cells derived from memory B cells preferentially homed to the bone marrow earlier and secreted increased levels of Abs when compared with primary plasma cells derived from naive B cells. Hence, memory B cells have the unique phenotype to differentiate into highly effective secondary plasma cells. PMID:24821969

  14. Cutting Edge: Primary and Secondary Effects of CD19 Deficiency on Cells of the Marginal Zone

    PubMed Central

    You, Yuying; Zhao, Hong; Wang, Yue; Carter, Robert H.

    2009-01-01

    Marginal zone (MZ) B cells are absent in CD19-/- mice. Possible causes include an intrinsic defect in B cells and/or a secondary defect in the extrinsic MZ microenvironment as a result of changes in B cell differentiation in mice lacking CD19. Cells in the MZ also include MZ macrophages (MZM) and MZ dendritic cells (DC). Although CD19 is only expressed on B cells, SIGN-R1+ MZM are absent and CD11c+ MZ DC distribution is abnormal in CD19-/- mice. Adoptively transferred B cells from normal mice are able to reconstitute MZ B cells in CD19-/- mice. In contrast, CD19-/- B cells could not enter the MZ of the normal mice. Furthermore, MZM distribution and MZ DC distribution are restored following MZ B cell reconstitution in CD19-/- mice. Thus, MZ B cells are required for MZM differentiation and MZ DC localization, but the deficiency of MZ B cells in CD19-/- mice is caused by a defect of intrinsic B cell signaling. PMID:19494255

  15. Cutting edge: Primary and secondary effects of CD19 deficiency on cells of the marginal zone.

    PubMed

    You, Yuying; Zhao, Hong; Wang, Yue; Carter, Robert H

    2009-06-15

    Marginal zone (MZ) B cells are absent in CD19(-/-) mice. Possible causes include an intrinsic defect in B cells and/or a secondary defect in the extrinsic MZ microenvironment as a result of changes in B cell differentiation in mice lacking CD19. Cells in the MZ also include MZ macrophages (MZM) and MZ dendritic cells (DC). Although CD19 is only expressed on B cells, SIGN-R1(+) MZM are absent and CD11c(+) MZ DC distribution is abnormal in CD19(-/-) mice. Adoptively transferred B cells from normal mice are able to reconstitute MZ B cells in CD19(-/-) mice. In contrast, CD19(-/-) B cells could not enter the MZ of the normal mice. Furthermore, MZM distribution and MZ DC distribution are restored following MZ B cell reconstitution in CD19(-/-) mice. Thus, MZ B cells are required for MZM differentiation and MZ DC localization, but the deficiency of MZ B cells in CD19(-/-) mice is caused by a defect of intrinsic B cell signaling. PMID:19494255

  16. Electrochemical photovoltaic cells/stabilization and optimization of II-VI semiconductors

    NASA Astrophysics Data System (ADS)

    Noufi, R.; Tench, D.; Warren, L.

    1981-03-01

    The bases for designing a practical electrochemical solar cell based on the II-VI compound semiconductors were investigated. Factors limiting the short circuit current of the n-CdSe photoanodes in the methanol/ferro-ferricyanide system were identified. Although the methanol/ferro-ferricyanide solution itself was found to be photolytically unstable, study of this system led to the identification of more promising nonaqueous redox electrolytes. Additional work on redox couple stabilization of n-CdX photoanodes was focused on both one- and two-electron couples. Very promising results were obtained for the alkylammonium chloro-Fe(II,III) couple in acetonitrile. Conducting polymer films of polypyrrole photoelectrochemically deposited onto n-type semiconductors were shown to protect these electrode materials from photocomposition while permitting electron exchange with the electrolyte, but poor adhesion has remained a key problem. Recently, improved adhesion has been attained for roughened semiconductor surfaces. In a basic aqueous ferro-ferricyanide electrolyte containing cyanide ion, the measured open circuit voltage for n-CdTe was 1.3 V, which is practically the bandgap for this material. It now appears that polypyrrole films are to some extent permeable to solvent/solute species since the film stability depends on the nature of the redox electrolyte, and semiconductor decomposition products seem to form underneath the film in some cases. Some work with polyaniline films was performed. Work on evaluating photocapacitance spectroscopy as a means of in situ characterization of semiconductor electrodes was focused on developing a reliable measurement technique.

  17. Electrochemical struvite precipitation from digestate with a fluidized bed cathode microbial electrolysis cell.

    PubMed

    Cusick, Roland D; Ullery, Mark L; Dempsey, Brian A; Logan, Bruce E

    2014-05-01

    Microbial electrolysis cells (MECs) can be used to simultaneously convert wastewater organics to hydrogen and precipitate struvite, but scale formation at the cathode surface can block catalytic active sites and limit extended operation. To promote bulk phase struvite precipitation and minimize cathode scaling, a two-chamber MEC was designed with a fluidized bed to produce suspended particles and inhibit scale formation on the cathode surface. MEC operation elevated the cathode pH to between 8.3 and 8.7 under continuous flow conditions. Soluble phosphorus removal using digester effluent ranged from 70 to 85% with current generation, compared to 10-20% for the control (open circuit conditions). At low current densities (?2 mA/m(2)), scouring of the cathode by fluidized particles prevented scale accumulation over a period of 8 days. There was nearly identical removal of soluble phosphorus and magnesium from solution, and an equimolar composition in the collected solids, supporting phosphorus removal by struvite formation. At an applied voltage of 1.0 V, energy consumption from the power supply and pumping (0.2 Wh/L, 7.5 Wh/g-P) was significantly less than that needed by other struvite formation methods based on pH adjustment such as aeration and NaOH addition. In the anode chamber, current generation led to COD oxidation (1.1-2.1 g-COD/L-d) and ammonium removal (7-12 mM) from digestate amended with 1 g/L of sodium acetate. These results indicate that a fluidized bed cathode MEC is a promising method of sustainable electrochemical nutrient and energy recovery method for nutrient rich wastewaters. PMID:24583521

  18. Electrochemical cell for in situ electrodeposition of magnetic thin films in a superconducting quantum interference device magnetometer.

    PubMed

    Topolovec, Stefan; Krenn, Heinz; Würschum, Roland

    2015-06-01

    An electrochemical cell is designed and applied for in situ electrodeposition of magnetic thin films in a commercial SQUID magnetometer system. The cell is constructed in such a way that any parasitic contribution of the cell and of the substrate for electrodeposition to the magnetic moment of the deposited film is reduced to a minimum. A remanent minor contribution is readily taken into account by a proper analysis of the detected signal. Thus, a precise determination of the absolute magnetic moment of the electrodeposited magnetic film during its growth and dissolution is achieved. The feasibility of the cell design is demonstrated by performing Co electrodeposition using cyclic voltammetry. For an average Co film thickness of (35.6 ± 3.0) atomic layers, a magnetic moment per Co atom of (1.75 ± 0.11) ?B was estimated, in good agreement with the literature bulk value. PMID:26133846

  19. Electrochemical cell for in situ electrodeposition of magnetic thin films in a superconducting quantum interference device magnetometer

    NASA Astrophysics Data System (ADS)

    Topolovec, Stefan; Krenn, Heinz; Würschum, Roland

    2015-06-01

    An electrochemical cell is designed and applied for in situ electrodeposition of magnetic thin films in a commercial SQUID magnetometer system. The cell is constructed in such a way that any parasitic contribution of the cell and of the substrate for electrodeposition to the magnetic moment of the deposited film is reduced to a minimum. A remanent minor contribution is readily taken into account by a proper analysis of the detected signal. Thus, a precise determination of the absolute magnetic moment of the electrodeposited magnetic film during its growth and dissolution is achieved. The feasibility of the cell design is demonstrated by performing Co electrodeposition using cyclic voltammetry. For an average Co film thickness of (35.6 ± 3.0) atomic layers, a magnetic moment per Co atom of (1.75 ± 0.11) ?B was estimated, in good agreement with the literature bulk value.

  20. A novel approach for analyzing electrochemical properties of mixed conducting solid oxide fuel cell anode materials by impedance spectroscopy.

    PubMed

    Nenning, A; Opitz, A K; Huber, T M; Fleig, J

    2014-10-28

    For application of acceptor-doped mixed conducting oxides as solid oxide fuel cell (SOFC) anodes, high electrochemical surface activity as well as acceptable electronic and ionic conductivity are crucial. In a reducing atmosphere, particularly the electronic conductivity of acceptor-doped oxides can become rather low and the resulting complex interplay of electrochemical reactions and charge transport processes makes a mechanistic interpretation of impedance measurements very complicated. In order to determine all relevant resistive and capacitive contributions of mixed conducting electrodes in a reducing atmosphere, a novel electrode design and impedance-based analysis technique is therefore introduced. Two interdigitating metallic current collectors are placed in a microelectrode, which allows in-plane measurements within the electrode as well as electrochemical measurements versus a counter electrode. Equivalent circuit models for quantifying the spectra of both measurement modes are developed and applied to simultaneously fit both spectra, using the same parameter set. In this manner, the electronic and ionic conductivity of the material as well as the area-specific resistance of the surface reaction and the chemical capacitance can be determined on a single microelectrode in a H2-H2O atmosphere. The applicability of this new tool was demonstrated in SrTi0.7Fe0.3O(3-?) (STFO) thin film microelectrodes, deposited on single-crystalline yttria-stabilized zirconia (YSZ) substrates. All materials parameters that contribute to the polarization resistance of STFO electrodes in a reducing atmosphere could thus be quantified. PMID:25219525

  1. Characterization of local electrochemical doping of high performance conjugated polymer for photovoltaics using scanning droplet cell microscopy?

    PubMed Central

    Gasiorowski, Jacek; Mardare, Andrei Ionut; Sariciftci, Niyazi Serdar; Hassel, Achim Walter

    2013-01-01

    The electrochemical oxidation of a next generation low bandgap high performance photovoltaic material namely poly[4,8-bis-substituted-benzo[1,2-b:4,5-b0]dithiophene-2,6-diyl-alt-4-substituted-thieno[3,4-b] thiophene-2,6-diyl] (PBDTTT-c) thin film was investigated using a scanning droplet cell microscope. Cyclic voltammetry was used for the basic characterization of the oxidation/doping of PBDTTT-c. Application of the different final potentials during the electrochemical study provides a close look to the oxidation kinetics. The electrical properties of both doped and undoped PBDTTT-c were analyzed in situ by electrochemical impedance spectroscopy giving the possibility to correlate the changes in the doping level with the subsequent changes in the resistance and capacitance. As a result one oxidation peak was found during the cyclic voltammetry and in potentiostatic measurements. From Mott–Schottky analysis a donor concentration of 2.3 × 1020 cm?3 and a flat band potential of 1.00 V vs. SHE were found. The oxidation process resulted in an increase of the conductivity by two orders of magnitude reaching a maximum for the oxidized form of 1.4 S cm?1. PMID:25843970

  2. Use of High Temperature Electrochemical Cells for Co-Generation of Chemicals and Electricity

    SciTech Connect

    Scott Barnett

    2007-09-30

    In this project, two key issues were addressed to show the feasibility of electrochemical partial oxidation (EPOx) in a SOFC. First, it was demonstrated that SOFCs can reliably operate directly with natural gas. These results are relevant to both direct-natural-gas SOFCs, where the aim is solely electrical power generation, and to EPOx. Second, it must be shown that SOFCs can work effectively as partial oxidation reactors, i.e, that they can provide high conversion efficiency of natural gas to syngas. The results of this study in both these areas look extremely promising. The main results are summarized briefly: (1) Stability and coke-free direct-methane SOFC operation is promoted by the addition of a thin porous inert barrier layer to the anode and the addition of small amounts of CO{sub 2} or air to the fuel stream; (2) Modeling results readily explained these improvements by a change in the gas composition at the Ni-YSZ anode to a non-coking condition; (3) The operation range for coke-free operation is greatly increased by using a cell geometry with a thin Ni-YSZ anode active layer on an inert porous ceramic support, i.e., (Sr,La)TiO{sub 3} or partially-stabilized zirconia (in segmented-in-series arrays); (4) Ethane and propane components in natural gas greatly increase coking both on the SOFC anode and on gas-feed tubes, but this can be mitigated by preferentially oxidizing these components prior to introduction into the fuel cell, the addition of a small amount of air to the fuel, and/or the use of ceramic-supported SOFC; (5) While a minimum SOFC current density was generally required to prevent coking, current interruptions of up to 8 minutes yielded only slight anode coking that caused no permanent damage and was completely reversible when the cell current was resumed; (6) Stable direct-methane SOFC operation was demonstrated under EPOx conditions in a 350 h test; (7) EPOx operation was demonstrated at 750 C that yielded 0.9 W/cm{sup 2} and a syngas production rate of 30 sccm/cm{sup 2}, and the reaction product composition was close to the equilibrium prediction during the early stages of cell testing; (8) The methane conversion to syngas continuously decreased during the first 100 h of cell testing, even though the cell electrical characteristics did not change, due to a steady decrease in the reforming activity of Ni-YSZ anodes; (9) The stability of methane conversion was substantially improved via the addition of a more stable reforming catalyst to the SOFC anode; (10) Modeling results indicated that a SOFC with anode barrier provides similar non-coking performance as an internal reforming SOFC, and provides a simpler approach with no need for a high-temperature exhaust-gas recycle pump; (11) Since there is little or no heat produced in the EPOx reaction, overall efficiency of the SOFC operated in this mode can, in theory, approach 100%; and (12) The combined value of the electricity and syngas produced allows the EPOx generator to be economically viable at a >2x higher cost/kW than a conventional SOFC.

  3. Alternating-polarity operation for complete regeneration of electrochemical deionization system

    DOEpatents

    Tran, Tri D. (Livermore, CA); Lenz, David J. (Livermore, CA)

    2002-01-01

    An electrically regeneratable battery of electrochemical cells for capacitive deionization (including electrochemical purification) and regeneration of electrodes is operated at alternate polarities during consecutive cycles. By polarizing the cells, ions are removed from the electrolyte and are held in the electric double layers formed at the carbon aerogel surfaces of the electrodes. As the electrodes of each cell of the battery are saturated with the removed ions, the battery is regenerated electrically at a reversed polarity from that during the deionization step of the cycle, thus significantly minimizing secondary wastes.

  4. Large-Scale Co-Expression Approach to Dissect Secondary Cell Wall Formation Across Plant Species

    PubMed Central

    Ruprecht, Colin; Mutwil, Marek; Saxe, Friederike; Eder, Michaela; Nikoloski, Zoran; Persson, Staffan

    2011-01-01

    Plant cell walls are complex composites largely consisting of carbohydrate-based polymers, and are generally divided into primary and secondary walls based on content and characteristics. Cellulose microfibrils constitute a major component of both primary and secondary cell walls and are synthesized at the plasma membrane by cellulose synthase (CESA) complexes. Several studies in Arabidopsis have demonstrated the power of co-expression analyses to identify new genes associated with secondary wall cellulose biosynthesis. However, across-species comparative co-expression analyses remain largely unexplored. Here, we compared co-expressed gene vicinity networks of primary and secondary wall CESAsin Arabidopsis, barley, rice, poplar, soybean, Medicago, and wheat, and identified gene families that are consistently co-regulated with cellulose biosynthesis. In addition to the expected polysaccharide acting enzymes, we also found many gene families associated with cytoskeleton, signaling, transcriptional regulation, oxidation, and protein degradation. Based on these analyses, we selected and biochemically analyzed T-DNA insertion lines corresponding to approximately twenty genes from gene families that re-occur in the co-expressed gene vicinity networks of secondary wall CESAs across the seven species. We developed a statistical pipeline using principal component analysis and optimal clustering based on silhouette width to analyze sugar profiles. One of the mutants, corresponding to a pinoresinol reductase gene, displayed disturbed xylem morphology and held lower levels of lignin molecules. We propose that this type of large-scale co-expression approach, coupled with statistical analysis of the cell wall contents, will be useful to facilitate rapid knowledge transfer across plant species. PMID:22639584

  5. The electrochemical generation of useful chemical species from lunar materials

    NASA Technical Reports Server (NTRS)

    Tsai, Kan J.; Kuchynka, Daniel J.; Sammells, Anthony F.

    1990-01-01

    Electrochemical cells have been fabricated for the simultaneous generation of oxygen and lithium from a Li2O-containing molten salt (Li2O-LiCl-LiF). The cell utilizes an oxygen vacancy conducting solid electrolyte, yttria-stabilized zirconia (YSZ), to effect separation between oxygen evolving and lithium reduction half-cell reactions. The cell, which operates at 700-850 C, possesses rapid electrode kinetics at the lithium-alloy electrode with exchange current density values being greater than 60 mA/sq cm. When used in the electrolytic mode, lithium produced at the negative electrode would be continuously removed from the cell for later use (under lunar conditions) as an easily storable reducing agent for the chemical refining of lunar ores. Because of the high reversibility of this electrochemical system, it has also formed the basis for the lithium-oxygen secondary battery system which possesses the highest theoretical energy density yet investigated.

  6. Charge-discharge characteristics of a solid-state Prussian blue secondary cell

    NASA Astrophysics Data System (ADS)

    Jayalakshmi, M.; Scholz, F.

    A solid-state secondary cell with Prussian blue, i.e., iron (III) hexacyanoferrate (II), as the active material of both the anode and cathode was constructed. The Prussian blue was mixed with graphite powder, potassium chloride and diluted hydrochloric acid to form a thick paste. A Nafion membrane was used as separator. The charge-discharge performance of the cell was studied in galvanostatic mode. For a stabilized cell, the cell voltage was invariably 1.0 V at half-discharge, whereas it varied from 2.0 to 1.0 V at half-charge depending on the charging rate. Double-step chronopotentiometric experiments were also carried out to understand the charge-discharge behaviour. The practical capacity was estimated to be 20 A h/kg from the maximum deliverable current on discharge. The cell was stable up to 60 cycles of charge-discharge and did not show any significant deterioration.

  7. Characterization of Damp-Heat Degradation of CuInGaSe2 Solar Cell Components and Devices by (Electrochemical) Impedance Spectroscopy: Preprint

    SciTech Connect

    Pern, F. J. J.; Noufi, R.

    2011-09-01

    This work evaluated the capability of (electrochemical) impedance spectroscopy (IS, or ECIS as used here) to monitor damp heat (DH) stability of contact materials, CuInGaSe2 (CIGS) solar cell components, and devices. Cell characteristics and its variation of the CIGS devices were also examined by the ECIS.

  8. Nonlinear coupled equations for electrochemical cells as developed by the general equation for nonequilibrium reversible-irreversible coupling.

    PubMed

    Bedeaux, Dick; Kjelstrup, Signe; Öttinger, Hans Christian

    2014-09-28

    We show how the Butler-Volmer and Nernst equations, as well as Peltier effects, are contained in the general equation for nonequilibrium reversible and irreversible coupling, GENERIC, with a unique definition of the overpotential. Linear flux-force relations are used to describe the transport in the homogeneous parts of the electrochemical system. For the electrode interface, we choose nonlinear flux-force relationships. We give the general thermodynamic basis for an example cell with oxygen electrodes and electrolyte from the solid oxide fuel cell. In the example cell, there are two activated chemical steps coupled also to thermal driving forces at the surface. The equilibrium exchange current density obtains contributions from both rate-limiting steps. The measured overpotential is identified at constant temperature and stationary states, in terms of the difference in electrochemical potential of products and reactants. Away from these conditions, new terms appear. The accompanying energy flux out of the surface, as well as the heat generation at the surface are formulated, adding to the general thermodynamic basis. PMID:25273407

  9. The Kv channel blocker 4-aminopyridine enhances Ag+ uptake: A scanning electrochemical microscopy study of single living cells

    PubMed Central

    Zhan, Dongping; Fan, Fu-Ren F.; Bard, Allen. J.

    2008-01-01

    We report that silver ion (Ag+) uptake is enhanced by 4-aminopyridine (4-AP), a well known voltage-sensitive potassium ion channel (Kv) blocker. Both bacterial (Escherichia coli) and mammalian (3T3 fibroblast) cells were used as model systems. Ag+ uptake was monitored with a scanning electrochemical microscope with an amperometric Ag+ ion-selective electrode (Ag+-ISE) and the respiration rates of E. coli cells were measured by oxygen reduction at an ultramicroelectrode. The results showed that not only the amount but also the rate of silver uptake by the cells increased significantly when 4-AP was added to the solution. For fibroblasts, the Ag+ uptake rate was 4.8 × 107 ions per cell per sec without 4-AP compared with 1.0 × 108 ions per cell per sec with 0.2 mM 4-AP. For E. coli cells, the uptake rate was 1.5 × 104 ions per cell per sec without 4-AP vs. 3.5 × 104 ions per cell per sec with 0.5 mM 4-AP and 5.9 × 104 ions per cell per sec with 1 mM 4-AP. Thus, 4-AP might be useful where silver is used as antimicrobial agent to speed its uptake. PMID:18719098

  10. Circulating hematopoietic stem cells in patients with choroidal neovascularization secondary to pathologic myopia

    Microsoft Academic Search

    M Sasahara; A Otani; Y Yodoi; N Gotoh; T Kameda; N Yoshimura

    2009-01-01

    BackgroundEmerging evidences suggest that circulating hematopoietic stem cells (HSCs) affect the pathogenesis of choroidal neovascularization (CNV), however, the roles of HSCs in CNV remain unclear in human population. The current study was designed to investigate the role of HSCs in the pathogenesis of CNV secondary to pathologic myopia (PM).MethodsWe clinically documented 78 patients with CNV in PM, and 35 of

  11. Evaluation of mixed solvent electrolytes for ambient temperature secondary lithium cells

    NASA Technical Reports Server (NTRS)

    Shen, D. H.; Subbarao, S.; Deligiannis, F.; Dawson, S.; Halpert, G.

    1988-01-01

    The ethylene carbonate/2-methyltetrahydrofuran (EC/2-MeTHF) mixed-solvent electrolyte has been experimentally found to possess many desirable electrolyte characteristics for ambient-temperature secondary Li-TiS2 cell applications. As many as 300 cycles have been demonstrated, and a cycling efficiency figure-of-merit of 38.5 percent, for 10-percent EC/90-percent MeTHF mixed-solvent electrolyte in experimental Li-TiS2 cells. The improved performance of this electrolyte is attributable to the formation of a beneficial passivating film on the Li electrode by interaction with the EC.

  12. Rigid and flexible organic electrochemical transistor arrays for monitoring action potentials from electrogenic cells.

    PubMed

    Yao, Chunlei; Li, Qianqian; Guo, Jing; Yan, Feng; Hsing, I-Ming

    2015-03-11

    Rigid and flexible organic electrochemical transistor arrays are successfully implemented for monitoring cardiac action potentials. Excellent signal to noise ratios are achieved with values routinely larger than 4. These devices are promising to be used in both conventional and emerging areas. PMID:25358525

  13. Fabrication of all-solid-state thin-film secondary cells using hexacyanometallate-based electrode materials

    NASA Astrophysics Data System (ADS)

    Eftekhari, Ali

    All-solid-state thin-film secondary cells were prepared using transition metal hexacyanometallates as anode and cathode materials. Two different approaches were employed to prepare highly stable films of the electroactive materials viz. using aluminum substrate as current collector and deposition under centrifugal forces. At the first stage, the cell design was examined for a well-known case, Prussian blue (PB) secondary cell. The experimental results were indicative of the fact that the cell properties such as its charge/discharge behavior, specific capacity, cyclability, and coulombic efficiency are significantly improved. At the second state, the cell design proposed was successfully used to fabricate a high-voltage secondary cell based on chromium hexacyanochromate (CrHCC) anode and Prussian blue (PB) cathode. Then, eight unit cells were connected in series to prepare a rechargeable battery with an operating voltage of ca. 20 V. Thus, the results are of interest for the preparation of microbatteries with specified properties.

  14. Abundance of mixed linkage glucan in mature tissues and secondary cell walls of grasses

    PubMed Central

    Vega-Sánchez, Miguel E.; Verhertbruggen, Yves; Scheller, Henrik V.; Ronald, Pamela C.

    2013-01-01

    (1,3; 1,4)-?-D-glucan, also known as mixed linkage glucan (MLG), is a polysaccharide that in flowering plants is unique to the cell walls of grasses and other related members of Poales. MLG is highly abundant in endosperm cell walls, where it is considered a storage carbohydrate. In vegetative tissues, MLG transiently accumulates in the primary cell walls of young, elongating organs. In evolutionary distant species such as Equisetum, MLG accumulates predominantly in old tissues in the stems. Similarly, we have recently shown that rice accumulates a large amount of MLG in mature stems, which prompted us to re-evaluate the hypothesis that MLG is solely related to growth in grass vegetative tissues. Here, we summarize data that confirms the presence of MLG in secondary cell walls and mature tissues in rice and other grasses. Along with these results, we discuss additional evidence indicating a broader role for MLG than previously considered. PMID:23299432

  15. Capacity decline of ambient temperature secondary Li-TiS2 cells

    NASA Technical Reports Server (NTRS)

    Subbarao, S.; Shen, D. H.; Huang, C.-K.; Deligiannis, F.; Halpert, G.; Peled, E.

    1990-01-01

    The main objective of the study described was to identify the causes responsible for the capacity losses observed during cycling of secondary Li-TiS2 cells. Experimental Li-TiS2 cells were fabricated and tested for their cycle life performance. The open circuit voltage of the cells was monitored during the rest period between the charging and discharging. The polarization at the Li and TiS2 electrodes was also monitored during cycling. Cycled cells were disassembled and the cathodes were analyzed by various analytical techniques. The results of the study indicate that the observed capacity loss is almost entirely due to the increased polarization of the TiS2 electrode with cycling. The electrolyte was found to degrade during cycling and the degradation products were found to deposit at the TiS2 electrode, which probably lead to the higher polarization.

  16. A Finite Strain Model of Stress, Diffusion, Plastic Flow and Electrochemical Reactions in a Lithium-ion Half-cell

    E-print Network

    Bower, Allan F; Sethuraman, Vijay A; 10.1016/j.jmps.2011.01.003

    2011-01-01

    We formulate the continuum field equations and constitutive equations that govern deformation, stress, and electric current flow in a Li-ion half-cell. The model considers mass transport through the system, deformation and stress in the anode and cathode, electrostatic fields, as well as the electrochemical reactions at the electrode/electrolyte interfaces. It extends existing analyses by accounting for the effects of finite strains and plastic flow in the electrodes, and by exploring in detail the role of stress in the electrochemical reactions at the electrode-electrolyte interfaces. In particular, we find that that stress directly influences the rest potential at the interface, so that a term involving stress must be added to the Nernst equation if the stress in the solid is significant. The model is used to predict the variation of stress and electric potential in a model 1-D half-cell, consisting of a thin film of Si on a rigid substrate, a fluid electrolyte layer, and a solid Li cathode. The predicted c...

  17. Effects of proton-exchange membrane fuel-cell operating conditions on charge transfer resistances measured by electrochemical impedance spectroscopy

    SciTech Connect

    Aaron, Doug S [ORNL; Yiacoumi, Sotira [Georgia Institute of Technology; Tsouris, Costas [ORNL

    2008-01-01

    Proton-exchange-membrane fuel cells (PEMFC) are highly dependent on operating conditions, such as humidity and temperature. This study employs electrochemical impedance spectroscopy (EIS) to measure the effects of operating parameters on internal proton and electron transport resistance mechanisms in the PEMFC. Current-density experiments have been performed to measure the power production in a 25 cm{sup 2} Nafion 117 PEMFC at varying operating conditions. These experiments have shown that low humidity and low temperature contribute to decreased power production. EIS is currently employed to provide a better understanding of the mechanisms involved in power production by calculating the specific resistances at various regions in the PEMFC. Experiments are performed at temperatures ranging from 30 to 50 C, feed humidities from 20 to 98%, and air stoichiometric ratios from 1.33 to 2.67. In all experiments, the hydrogen feed stoichiometric ratio was approximately 4.0. EIS is used to identify which transport steps limit the power production of the PEMFC over these ranges of conditions. The experimental data are analyzed via comparison to equivalent circuit models (ECMs), a technique that uses an electrical circuit to represent the electrochemical and transport properties of the PEMFC. These studies will aid in designing fuel cells that are more tolerant to wide-ranging operating conditions. In addition, optimal operating conditions for PEMFC operation can be identified.

  18. Analysis of Phthalate Esters in Mammalian Cell Culture Using a Microfluidic Channel Coupled with an Electrochemical Sensor.

    PubMed

    Noh, Hui-Bog; Gurudatt, Nanjanagudu Ganesh; Won, Mi-Sook; Shim, Yoon-Bo

    2015-07-21

    An analytical tool to monitor trace phthalate was developed using a microfluidic channel device coupled with a novel electrochemical biosensor. At first, the electrochemical sensor was constructed with biomimetic layers to reveal a large hydrogen over potential by controlling the surface charge and hydrophobicity through assembling with a lipid (1,2-dioleoyl-sn-glycero-3-phosphoethanolamine) and a cationic molecule (toluidine blue O) bonded to a conductive polymer. The modified electrode possessing a highly negative polarization potential (approximately -1.8 V vs Ag/AgCl) can uptake sparingly soluble phthalate ester (PEs) compounds in aqueous media. Each sensor probe material was characterized employing SEM, AFM, XPS, QCM, TEM, UV-visible, and impedance spectroscopy. The microfluidic channel is used first to concentrate and separate trace amounts of phthalates, and then the sensor probe is installed at the end of channel. Experimental variables affecting the PEs analysis were assessed and optimized in terms of biomimetic layer composition and analytical conditions. The linear dynamic range and detection limits of the PEs were 0.15 nM-10.0 ?M and ?12.5 pM with relative standard deviations <5%. The proposed method was applied to evaluate the effect of endocrine disruptors on mammalian kidney cells, where the cell samples show in-taking percentages between 1.8 and 7.0% to the total PEs according to the incubation time. PMID:26088015

  19. Role of secondary lymphoid tissues in primary and memory T-cell responses to a transplanted organ

    PubMed Central

    Ng, Yue-Harn; Chalasani, Geetha

    2009-01-01

    Secondary lymphoid tissues are the hub of adaptive immune responses wherein rare cognate lymphocytes encounter dendritic cells bearing antigen from peripheral tissues and differentiate into effector and memory cells that eliminate antigen. It is accepted that immune responses against microbial and tumor antigens are initiated within secondary lymphoid tissues. There is less agreement on whether the same principle applies to immune responses to a transplanted organ because an allograft expresses foreign major histocompatibility complex and contains donor antigen presenting cells that could activate T cells directly in situ leading to rejection. Recent studies confirm that although naïve T cells can be primed within the allograft, their differentiation to effect rejection is dependent on secondary lymphoid tissues. Antigen-experienced memory T cells, unlike Naïve T cells, function largely independent of secondary lymphoid tissues to cause allograft rejection. In an alloimmune response, secondary lymphoid tissues support not only immune activation but also immune regulation essential for allograft survival. Here, we will review recent findings and discuss the role of secondary lymphoid tissues in primary and memory alloimmune responses. PMID:19846289

  20. Prevention of secondary stroke and resolution of transfusional iron overload in children with sickle cell anemia using hydroxyurea and phlebotomy

    Microsoft Academic Search

    Russell E. Ware; Sherri A. Zimmerman; Pamela B. Sylvestre; Nicole A. Mortier; Jacqueline S. Davis; William R. Treem; William H. Schultz

    2004-01-01

    ObjectiveTransfusions prevent secondary stroke in children with sickle cell anemia (SCA) but also cause iron overload. Alternatives for stroke prophylaxis with effective therapy to reduce iron burden are needed.

  1. Analysis of cytogenetic effects of the secondary radiation resulting from 70 GeV protons of chinese hamster cells

    NASA Astrophysics Data System (ADS)

    Akhmadieva, A. Kh.; Aptikaeva, G. Ph.; Livanova, I. A.; Antipov, A. V.; Akoev, I. G.; Ganassi, E. E.

    The cell culture of a Chinese hamster was irradiated on a Serpuchov proton synchrotron at a dose of 0.5-4 Gy and a dose rate of 1 Gy/min and by gamma-irradiation at dose 1-5 Gy and dose rate 1.2-1.4 Gy/min. The effect of radiation on the cell culture was judged from chromosomal aberrations in G2-stage of cell cycle and micronuclear test. The relative biological efficience of the secondary radiation was approximately 3. Modifying effect of caffeine on the cells irradiated by secondary radiation of synchrotron was not observed. In the presence of caffeine the effect of ?-irradiation practically is increased up to the level observed upon secondary irradiation. This suggests that secondary radiation inhibits the repair of the cytogenetic damage.

  2. In?situ X-ray spectromicroscopy investigation of the material stability of SOFC metal interconnects in operating electrochemical cells.

    PubMed

    Bozzini, Benedetto; Tondo, Elisabetta; Prasciolu, Mauro; Amati, Matteo; Abyaneh, Majid Kazemian; Gregoratti, Luca; Kiskinova, Maya

    2011-08-22

    The present in situ study of electrochemically induced processes occurring in Cr/Ni bilayers in contact with a YSZ electrolyte aims at a molecular-level understanding of the fundamental aspects related to the durability of metallic interconnects in solid oxide fuel cells (SOFCs). The results demonstrate the potential of scanning photoelectron microspectroscopy and imaging to follow in situ the evolution of the chemical states and lateral distributions of the constituent elements (Ni, Cr, Zr, and Y) as a function of applied cathodic potential in a cell working at 650 °C in 10(-6) mbar O(2) ambient conditions. The most interesting findings are the temperature-induced and potential-dependent diffusion of Ni and Cr, and the oxidation-reduction processes resulting in specific morphology-composition changes in the Ni, Cr, and YSZ areas. PMID:21695791

  3. Investigation of chemical and electrochemical reactions mechanisms in a direct carbon fuel cell using olive wood charcoal as sustainable fuel

    NASA Astrophysics Data System (ADS)

    Elleuch, Amal; Halouani, Kamel; Li, Yongdan

    2015-05-01

    Direct carbon fuel cell (DCFC) is a high temperature fuel cell using solid carbon as fuel. The use of environmentally friendly carbon material constitutes a promising option for the DCFC future. In this context, this paper focuses on the use of biomass-derived charcoal renewable fuel. A practical investigation of Tunisian olive wood charcoal (OW-C) in planar DCFCs is conducted and good power density (105 mW cm-2) and higher current density (550 mA cm-2) are obtained at 700 °C. Analytical and predictive techniques are performed to explore the relationships between fuel properties and DCFC chemical and electrochemical mechanisms. High carbon content, carbon-oxygen groups and disordered structure, are the key parameters allowing the achieved good performance. Relatively complex chain reactions are predicted to explain the gas evolution within the anode. CO, H2 and CH4 participation in the anodic reaction is proved.

  4. Half-Cell Potential Analysis of an Ammonia Sensor with the Electrochemical Cell Au | YSZ | Au, V2O5-WO3-TiO2

    PubMed Central

    Schönauer-Kamin, Daniela; Fleischer, Maximilian; Moos, Ralf

    2013-01-01

    Half-cell potentials of the electrochemical cell Au, VWT | YSZ | Au are analyzed in dependence on oxygen and ammonia concentration at 550 °C. One of the gold electrodes is covered with a porous SCR catalyst, vanadia-tungstenia-titania (VWT). The cell is utilized as a potentiometric ammonia gas sensor and provides a semi-logarithmic characteristic curve with a high NH3 sensitivity and selectivity. The analyses of the Au | YSZ and Au, VWT | YSZ half-cells are conducted to describe the non-equilibrium behavior of the sensor device in light of mixed potential theory. Both electrode potentials provide a dependency on the NH3 concentration, whereby VWT, Au | YSZ shows a stronger effect which increases with increasing VWT coverage. The potential shifts in the anodic direction confirm the formation of mixed potentials at both electrodes resulting from electrochemical reactions of O2 and NH3 at the three-phase boundary. Polarization curves indicate Butler-Volmer-type kinetics. Modified polarization curves of the VWT covered electrode show an enhanced anodic reaction and an almost unaltered cathodic reaction. The NH3 dependency is dominated by the VWT coverage and it turns out that the catalytic properties of the VWT thick film are responsible for the electrode potential shift. PMID:23575035

  5. Impact of secondary barriers on copper-indium-gallium-selenide solar-cell operation

    NASA Astrophysics Data System (ADS)

    Pudov, Alexei O.

    Thin-film solar cells based on CuInSe2 (CIS) absorber with a band gap of Eg = 1.0 eV and also based on CuIn1-x GaxSe2 (CIGS) alloy absorbers with a band-gap range of Eg = 1.0--1.67 eV are investigated in this work. Intermediate "buffer" semiconductor layers in p-n junctions of CIGS solar cells often improve photodiode properties of the devices. The primary goal of the thesis is to study secondary barriers in the conduction band at the buffer/absorber interface, which may limit current transport and thus reduce the efficiency of the solar cells. The secondary goal is to explore alternative wide-bandgap buffers in CIGS cell structures. CIGS cells with standard CdS buffer layers, and alternative ZnS(O,OH) and InS(O,OH) buffer layers were studied. CdS/CuIn1-xGaxSe2 solar cells with variable Ga content have a range of conduction-band offsets (DeltaEc) in the junction from moderately positive (spike offsets) in CdS/CuInSe2 to moderately negative (cliff offsets) in CdS/CuGaSe 2. Moderate conduction-band spikes in CdS/CIS and low-Ga CdS/CIGS are expected to cause distortions in diode current-voltage (J-V) curves of such solar cells under "red" illumination (hnu < Eg(buffer)); no J-V distortions are expected for high-Ga CdS/CIGS with cliff offsets. These predictions were confirmed in experiments: the distortions were absent for cells with Eg above 1.2--1.3 eV, at which CdS/CIGS DeltaE c is near zero. Experiments and numerical simulations showed that one approach to reduce secondary barriers and J-V distortions in low-Ga high-spike cells is to thin the buffer layer(s). Blue photons (hnu above Eg(buffer)) in the solar spectrum induce photoconductivity in the otherwise compensated buffers, which also results in lowering of the secondary barriers. It was shown that CIGS cells with CdS, InS(O,OH), and ZnS(O,OH) buffers have a similar response to "blue" photons: J-V distortion, if present under red light, is reduced or entirely disappears with blue-light exposure within minutes. The distortion re-appearance without blue light is the order of a thousand times slower. Using wider-gap buffers, such as InS(O,OH) and ZnS(O,OH), was shown to produce higher photocurrents in solar cells. This photocurrent improvement is a central direction in the effort of further increasing efficiencies of thin-film solar cells.

  6. Giant cell tumor of the talus with secondary aneurysmal bone cyst.

    PubMed

    Kinley, S; Wiseman, F; Wertheimer, S J

    1993-01-01

    Giant cell tumors of the talus are very uncommon. Secondary aneurysmal bone cyst changes are well documented in the literature with giant cell tumors being one of the most common underlying lesions. However, no previous case of this combination has been documented in the podiatric literature. The diagnosis of these lesions can be very challenging since they share many common features. Although previous reports describe a higher recurrence rate of giant cell tumors when found in the small bones of the hands and feet, reported cases of this entity in the talus indicate a less aggressive natural history with rare malignant transformation. A case report and review of the literature are presented. PMID:8318960

  7. NAC-MYB-based transcriptional regulation of secondary cell wall biosynthesis in land plants

    PubMed Central

    Nakano, Yoshimi; Yamaguchi, Masatoshi; Endo, Hitoshi; Rejab, Nur Ardiyana; Ohtani, Misato

    2015-01-01

    Plant cells biosynthesize primary cell walls (PCW) in all cells and produce secondary cell walls (SCWs) in specific cell types that conduct water and/or provide mechanical support, such as xylem vessels and fibers. The characteristic mechanical stiffness, chemical recalcitrance, and hydrophobic nature of SCWs result from the organization of SCW-specific biopolymers, i.e., highly ordered cellulose, hemicellulose, and lignin. Synthesis of these SCW-specific biopolymers requires SCW-specific enzymes that are regulated by SCW-specific transcription factors. In this review, we summarize our current knowledge of the transcriptional regulation of SCW formation in plant cells. Advances in research on SCW biosynthesis during the past decade have expanded our understanding of the transcriptional regulation of SCW formation, particularly the functions of the NAC and MYB transcription factors. Focusing on the NAC-MYB-based transcriptional network, we discuss the regulatory systems that evolved in land plants to modify the cell wall to serve as a key component of structures that conduct water and provide mechanical support. PMID:25999964

  8. Progress in the development of the hollow fiber sodium-sulfur secondary cell

    NASA Technical Reports Server (NTRS)

    Levine, C. A.

    1975-01-01

    This report describes the development and status of the sodium-sulfur secondary cell which uses fine hollow glass fibers as the electrolyte. Laboratory size cells containing up to 7000 fibers and having capacities up to 5 ampere-hours have been built and operated. These cells have been run at various cycle depths up to 95% of capacity. Lifetime does not depend on depth of discharge up to at least 50% depth and possibly deeper. Rates of charge and discharge of the nominally one hour cells have been varied from three times the design rate to 0.05 times the design rate. Smaller cells operate with essentially no internal resistance increase during their lifetimes of over four months on continuous charge/discharge at the one hour rate. Larger cells assembled with somewhat different mechanical assembly techniques have shorter lives. Two types of failure modes are observed: progressive weakening and breaking of the fibers inside the cell assembly, and fiber breakage at the fiber/tube sheet interface.

  9. The effect of cathodic electrochemical potential of Ti-6Al-4V on cell viability: voltage threshold and time dependence.

    PubMed

    Sivan, Shiril; Kaul, Shereen; Gilbert, Jeremy L

    2013-11-01

    The biocompatibility of metallic biomaterials is dependent on the redox state of the surface and its effect on cellular redox equilibrium. When metallic biomaterials experience mechanically assisted corrosion such as fretting, there is a drop in the voltage of its surface. Studies have demonstrated that cell viability is significantly degraded by sustained cathodic excursion in voltage of metallic biomaterials below a critical potential between -300 and -600 mV on commercially pure titanium. Cells cultured at above -300 mV showed little loss in viability whereas cells cultured on -600 mV Ti were almost 100% killed at 24 h. The goal of this study is to concisely define the voltage threshold and time-dependence of the cell killing effect seen on titanium surfaces. MC3T3 cells were cultured on electrochemically controlled Ti-6Al-4V surfaces at voltages ranging from -300 to -1000 mV for time periods ranging from 1 to 24 h. Cell viability and morphology was monitored with live-dead assay and scanning electron microscopy. Cell viability decreased from -300 to -400 mV and exhibited time-dependence where the more cathodic the potential, the faster the drop-off of viability. Hundred percent cell killing took as little as 4 h at -1000 mV and required 24 h at -400 mV. Sustained net cathodic currents with densities as low as 0.1 ?A/cm(2) are observed during cell killing. This work shows reduction reactions are an important element of cellular viability in a time and potential dependent way and may explain why mechanically assisted corrosion reactions may lead to increased cell killing in metallic implants. Note: All voltages are versus Ag/AgCl. PMID:23894023

  10. Activation of cytokine genes in T cells during primary and secondary murine influenza pneumonia.

    PubMed

    Carding, S R; Allan, W; McMickle, A; Doherty, P C

    1993-02-01

    The patterns of cytokine mRNA expression in mice with primary or secondary influenza pneumonia have been assessed by in situ hybridization analysis of cells from both the mediastinal lymph node (MLN) and the virus-infected lung. Evidence of substantial transcriptional activity was found in all lymphocyte subsets recovered from both anatomical sites. The kinetics of cytokine mRNA expression after primary infection with an H3N2 virus were in accord with the idea that the initial response occurs in regional lymphoid tissue, with the effector T cells later moving to the lung. This temporal separation was much less apparent for the more rapid secondary response resulting from challenge of H3N2-primed mice with an H1N1 virus. Among the T cell receptor alpha/beta+ subsets, transcripts for interferon (IFN) gamma and tumor necrosis factor beta were most commonly found in the CD8+ population whereas mRNA for interleukin (IL) 4 and IL-10 was much more prevalent in CD4+ T cells. The gamma/delta T cells expressed mRNA for all cytokines tested, with IL-2, IL-4, and IFN-gamma predominating among those recovered from the inflammatory exudate. At particular time points, especially early in the MLN and late in the infected lung, the frequency of mRNA+ lymphocytes was much higher than would be expected from current understanding of the prevalence of virus-specific precursors and effectors. If this response is typical, induction of cytokine gene expression for T cells that are not responding directly to the invading pathogen may be a prominent feature of acute virus infections. PMID:8426116

  11. Electrochemical fabrication of capacitors

    DOEpatents

    Mansour, Azzam N. (Fairfax Sta., VA); Melendres, Carlos A. (Lemont, IL)

    1999-01-01

    A film of nickel oxide is anodically deposited on a graphite sheet held in osition on an electrochemical cell during application of a positive electrode voltage to the graphite sheet while exposed to an electrolytic nickel oxide solution within a volumetrically variable chamber of the cell. An angularly orientated x-ray beam is admitted into the cell for transmission through the deposited nickel oxide film in order to obtain structural information while the film is subject to electrochemical and in-situ x-ray spectroscopy from which optimum film thickness, may be determined by comparative analysis for capacitor fabrication purposes.

  12. Electrochemical behavior and biological response of Mesenchymal Stem Cells on cp-Ti after N-ions implantation

    NASA Astrophysics Data System (ADS)

    Rizwan, M.; Ahmad, A.; Deen, K. M.; Haider, W.

    2014-11-01

    Titanium and its alloys are most widely used as implant materials due to their excellent biocompatibility, mechanical properties and chemical stability. In this study Nitrogen ions of known dosage were implanted over cp-Ti by Pelletron accelerator with beam energy of 0.25 MeV.The atomic force microscopy of bare and nitrogen implanted specimens confirmed increase in surface roughness with increase in nitrogen ions concentration. X-ray diffraction patterns of ions implanted surfaces validated the formation of TiN0.3 and Ti3N2-xnitride phases. The tendency to form passive film and electrochemical behavior of these surfaces in ringer lactate (RL) solution was evaluated by Potentiodynamic polarization and electrochemical impedance spectroscopy respectively. It is proved that nitrogen ions implantation was beneficial to reduce corrosion rate and stabilizing passive film by increasing charge transfer resistance in RL. It was concluded that morphology and proliferation of Mesenchymal Stem Cells on nitrogen ions implanted surfaces strongly depends on surface roughness and nitride phases.

  13. The electrochemical characteristics of air fuel cell electrodes used in an electrolytic system for spent chromium plating solution regeneration

    NASA Astrophysics Data System (ADS)

    Huang, Kuo-Lin; Holsen, Thomas M.; Selman, J. R.; Chou, Tse-Chuan

    The electrochemical characteristics of lab prepared Pt|Nafion and commercial Pt-C|Nafion air fuel cell electrodes in sulfuric and chromic acid electrolytes were examined to help in the design of an electrochemical system that might potentially be used in the regeneration of spent chromium plating solutions to save energy. In both solutions, the Pt-C|Nafion electrode obtained higher cathodic currents from oxygen reduction than the Pt|Nafion electrode, mainly due to an order of magnitude greater active area in the Pt-C|Nafion than in the Pt|Nafion electrode. The currents significantly increased after the cathodic sweeps passed ˜0.7-0.8 V versus a standard hydrogen electrode (SHE) in both systems. The currents for the oxygen reduction reactions were higher in the sulfuric acid system than in the chromic acid system, which were associated with less available electroactive sites on the electrodes and/or the inhibition of oxygen reduction in the chromic acid. In addition, impurities (i.e., Cu) were more difficult to deposit on Pt in the chromic acid than in the sulfuric acid. In sulfuric acid, the Tafel slopes were similar for the two electrodes, but in chromic acid, the Pt-C|Nafion electrode had a Tafel slope close to -120 mV decade -1 while the Pt|Nafion did not have a clear Tafel region in ˜600-400 mV versus Ag/AgCl. The polarization results suggest that, in practical applications, flooding, if it occurs, will be more responsible than slow oxygen reduction kinetics for the cathodic potential/cell voltage increase in the fuel cell cathode system using chromic acid.

  14. Electrochemical Polarization-Induced Changes in the Growth of Individual Cells and Biofilms of Pseudomonas fluorescens (ATCC 17552)

    PubMed Central

    Busalmen, Juan Pablo; de Sánchez, Susana R.

    2005-01-01

    The effect of surface electrochemical polarization on the growth of cells of Pseudomonas fluorescens (ATCC 17552) on gold electrodes has been examined. Potentials positive or negative to the potential of zero charge (PZC) of gold were applied, and these resulted in changes in cell morphology, size at cell division, time to division, and biofilm structure. At ?0.2 V (Ag/AgCl-3 M NaCl), cells elongated at a rate of up to 0.19 ?m min?1, rendering daughter cells that reached up to 3.8 ?m immediately after division. The doubling time for the entire population, estimated from the increment in the fraction of surface covered by bacteria, was 82 ± 7 min. Eight-hour-old biofilms at ?0.2 V were composed of large cells distributed in expanded mushroom-like microcolonies that protruded several micrometers in the solution. A different behavior was observed under positive polarization. At an applied potential of 0.5 V, the doubling time of the population was 103 ± 8 min, cells elongated at a lower rate (up to 0.08 ?m min?1), rendering shorter daughters (2.5 ± 0.5 ?m) after division, although the duplication times were virtually the same at all potentials. Biofilms grown under this positive potential were composed of short cells distributed in a large number of compact microcolonies. These were flatter than those grown at ?0.2 V or at the PZC and were pyramidal in shape. Polarization effects on cell growth and biofilm structure resembled those previously reported as produced by changes in the nutritional level of the culture medium. PMID:16204543

  15. Label-free electrochemical aptasensor constructed by layer-by-layer technology for sensitive and selective detection of cancer cells.

    PubMed

    Wang, Tianshu; Liu, Jiyang; Gu, Xiaoxiao; Li, Dan; Wang, Jin; Wang, Erkang

    2015-07-01

    Here, a cytosensor was constructed with ferrocene-appended poly(allylamine hydrochloride) (Fc-PAH) functionalized graphene (Fc-PAH-G), poly(sodium-p-styrenesulfonate) (PSS) and aptamer (AS1411) by layer-by-layer assembly technology. The hybrid nanocomposite Fc-PAH-G not only brings probes on the electrode and also promotes electron transfer between the probes and the substrate electrode. Meanwhile, LBL technology provides more effective probes to enhance amplified signal for improving the sensitivity of the detection. While AS1411 forming G-quardruplex structure and binding cancer cells, the current response of the sensing electrode decreased due to the insulating properties of cellular membrane. Differential pulse voltammetry (DPV) was performed to investigate the electrochemical detection of HeLa cells attributing to its sensitivity of the current signal change. The as-prepared aptasensor showed a high sensitivity and good stability, a widely detection range from 10 to 10(6)cells/mL with a detection limit as low as 10cells/mL for the detection of cancer cells. PMID:26043089

  16. Tanshinone-1 induces tumor cell killing, enhanced by inhibition of secondary activation of signaling networks

    PubMed Central

    Xu, L; Feng, J-M; Li, J-X; Zhu, J-M; Song, S-S; Tong, L-J; Chen, Y; Yang, X-Y; Shen, Y-Y; Lian, F-L; Li, Y-P; Lin, D-H; Ding, J; Miao, Z-H

    2013-01-01

    Tumor multidrug resistance (MDR) can result from overexpression of drug transporters and deregulation of cellular signaling transduction. New agents and strategies are required for overcoming MDR. Here, we report that tanshinone-1, a bioactive ingredient in traditional Chinese medicine, directly killed MDR tumor cells and their corresponding parental cells, which was potentiated by inhibition of secondary activation of signaling networks. Tanshinone-1 was slightly more potent at inducing cytotoxicity and apoptosis in MDR cells than in corresponding parental cells. Tanshinone-1-induced MDR cell killing was independent of the function and expression of drug transporters but was partially correlated with the phosphatase-dependent reduction of phospho-705-Stat3, which secondarily activated p38-, AKT-, and ERK-involved signaling networks. Cotreatments with p38, AKT, and ERK inhibitors potentiated the anti-MDR effects of tanshinone-1. Our study presents a model for MDR cell killing using a compound of natural origin. This model could lead to new therapeutic strategies for targeting signaling network(s) in MDR cancers as well as new strategies for multitarget design. PMID:24201804

  17. Chip-based generation of carbon nanodots via electrochemical oxidation of screen printed carbon electrodes and the applications for efficient cell imaging and electrochemiluminescence enhancement.

    PubMed

    Xu, Yuanhong; Liu, Jingquan; Zhang, Jizhen; Zong, Xidan; Jia, Xiaofang; Li, Dan; Wang, Erkang

    2015-06-01

    A portable lab-on-a-chip methodology to generate ionic liquid-functionalized carbon nanodots (CNDs) was developed via electrochemical oxidation of screen printed carbon electrodes. The CNDs can be successfully applied for efficient cell imaging and solid-state electrochemiluminescence sensor fabrication on the paper-based chips. PMID:25959400

  18. Thermal-fluid and electrochemical modeling and performance study of a planar solid oxide electrolysis cell : analysis on SOEC resistances, size, and inlet flow conditions

    Microsoft Academic Search

    B. Yildiz; J. Smith; T. Sofu

    2008-01-01

    Argonne National Laboratory and Idaho National Laboratory researchers are analyzing the electrochemical and thermal-fluid behavior of solid oxide electrolysis cells (SOECs) for high temperature steam electrolysis using computational fluid dynamics (CFD) techniques. The major challenges facing commercialization of steam electrolysis technology are related to efficiency, cost, and durability of the SOECs. The goal of this effort is to guide the

  19. Mesenchymal Stem Cell-Based Treatment for Microvascular and Secondary Complications of Diabetes Mellitus

    PubMed Central

    Davey, Grace C.; Patil, Swapnil B.; O’Loughlin, Aonghus; O’Brien, Timothy

    2014-01-01

    The worldwide increase in the prevalence of Diabetes mellitus (DM) has highlighted the need for increased research efforts into treatment options for both the disease itself and its associated complications. In recent years, mesenchymal stromal cells (MSCs) have been highlighted as a new emerging regenerative therapy due to their multipotency but also due to their paracrine secretion of angiogenic factors, cytokines, and immunomodulatory substances. This review focuses on the potential use of MSCs as a regenerative medicine in microvascular and secondary complications of DM and will discuss the challenges and future prospects of MSCs as a regenerative therapy in this field. MSCs are believed to have an important role in tissue repair. Evidence in recent years has demonstrated that MSCs have potent immunomodulatory functions resulting in active suppression of various components of the host immune response. MSCs may also have glucose lowering properties providing another attractive and unique feature of this therapeutic approach. Through a combination of the above characteristics, MSCs have been shown to exert beneficial effects in pre-clinical models of diabetic complications prompting initial clinical studies in diabetic wound healing and nephropathy. Challenges that remain in the clinical translation of MSC therapy include issues of MSC heterogeneity, optimal mode of cell delivery, homing of these cells to tissues of interest with high efficiency, clinically meaningful engraftment, and challenges with cell manufacture. An issue of added importance is whether an autologous or allogeneic approach will be used. In summary, MSC administration has significant potential in the treatment of diabetic microvascular and secondary complications but challenges remain in terms of engraftment, persistence, tissue targeting, and cell manufacture PMID:24936198

  20. Secondary lithium batteries for space applications

    NASA Technical Reports Server (NTRS)

    Carter, B.; Khanna, S. K.; Yen, S. P. S.; Shen, D.; Somoano, R. B.

    1981-01-01

    Secondary lithium cells which use a LiAsF6-2-Me-THF electrolyte and a TiS2 intercalatable cathode exhibit encouraging cycle life at ambient temperature. Electrochemical and surface analytical studies indicate that the electrolyte is unstable in the presence of metallic lithium, leading to the formation of a lithium passivating film composed of lithium arsenic oxyfluorides and lithium fluorsilicates. The lithium cyclability remains as the most important problem to solve. Different electrolyte solvents, such as sulfolane, exhibit promising characteristics but lead to new compatibility problems with the other cell component materials.

  1. Hemophagocytic lymphohistiocytosis secondary to T-cell/histiocyte-rich large B-cell lymphoma.

    PubMed

    Devitt, Katherine; Cerny, Jan; Switzer, Bradley; Ramanathan, Muthalagu; Nath, Rajneesh; Yu, Hongbo; Woda, Bruce A; Chen, Benjamin J

    2014-01-01

    Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening clinical syndrome characterized by dysregulation of the immune system. Impaired function of cytotoxic T cells and natural killer cells is often seen, and T-cell malignancies represent most cases of lymphoma-associated HLH. HLH associated with B-cell lymphoma is rare. We describe a case of a 30-year-old man who presented with fever, splenomegaly, and hyperferritinemia. Bone marrow biopsy revealed T-cell/histiocyte-rich large B-cell lymphoma, a rare, aggressive B-cell malignancy. This case highlights the interplay between a pro-inflammatory cytokine microenvironment and tumor-mediated immune suppression, and addresses the importance of accurately diagnosing these entities for appropriate clinical management. PMID:24955327

  2. Fabrication of advanced electrochemical energy materials using sol-gel processing techniques

    NASA Technical Reports Server (NTRS)

    Chu, C. T.; Chu, Jay; Zheng, Haixing

    1995-01-01

    Advanced materials play an important role in electrochemical energy devices such as batteries, fuel cells, and electrochemical capacitors. They are being used as both electrodes and electrolytes. Sol-gel processing is a versatile solution technique used in fabrication of ceramic materials with tailored stoichiometry, microstructure, and properties. The application of sol-gel processing in the fabrication of advanced electrochemical energy materials will be presented. The potentials of sol-gel derived materials for electrochemical energy applications will be discussed along with some examples of successful applications. Sol-gel derived metal oxide electrode materials such as V2O5 cathodes have been demonstrated in solid-slate thin film batteries; solid electrolytes materials such as beta-alumina for advanced secondary batteries had been prepared by the sol-gel technique long time ago; and high surface area transition metal compounds for capacitive energy storage applications can also be synthesized with this method.

  3. Electrochemical Analysis of Neurotransmitters.

    PubMed

    Bucher, Elizabeth S; Wightman, R Mark

    2015-07-22

    Chemical signaling through the release of neurotransmitters into the extracellular space is the primary means of communication between neurons. More than four decades ago, Ralph Adams and his colleagues realized the utility of electrochemical methods for the study of easily oxidizable neurotransmitters, such as dopamine, norepinephrine, and serotonin and their metabolites. Today, electrochemical techniques are frequently coupled to microelectrodes to enable spatially resolved recordings of rapid neurotransmitter dynamics in a variety of biological preparations spanning from single cells to the intact brain of behaving animals. In this review, we provide a basic overview of the principles underlying constant-potential amperometry and fast-scan cyclic voltammetry, the most commonly employed electrochemical techniques, and the general application of these methods to the study of neurotransmission. We thereafter discuss several recent developments in sensor design and experimental methodology that are challenging the current limitations defining the application of electrochemical methods to neurotransmitter measurements. PMID:25939038

  4. Porous silicon layers prepared by electrochemical etching for application in silicon thin film solar cells

    NASA Astrophysics Data System (ADS)

    Dubey, R. S.; Gautam, D. K.

    2011-09-01

    In this paper, multilayer structures of porous silicon were fabricated by using electrochemical etching and characterized for its optical properties and surface morphology. Samples of monolayer of porous silicon were grown to study the characteristics of porous layer formation with respect to applied current density, etching time and hydrofluoric acid concentrations. Photoluminescence peaks of red emission at wavelength 695 and 650 nm were observed from multilayer porous silicon structures. By atomic force microscopy measurement, hillocks like surface were clearly observed within the host material, which confirmed the formation of pores.

  5. Exposure of BEAS-2B cells to secondary organic aerosol coated on magnetic nanoparticles.

    PubMed

    Jang, Myoseon; Ghio, Andrew J; Cao, Gang

    2006-08-01

    Toxicological investigation suggests that exposures to complex secondary organic aerosol (SOA) products can result in adverse health effects in biological systems. However, the mechanism of adverse health effects is not yet understood. One of the major restrictions in studies of health effects of SOA is a particle exposure technique. In this study, we applied an innovative soft targeting technology using magnetic nanoparticles (MNP) to deliver SOAs onto target biological systems under a magnetic field. The exploratory exposure technology using MNP was demonstrated for the SOAs created from the reaction of ozone with alpha-pinene in an indoor Teflon film chamber. SOA increased the release of the proinflammatory mediator interleukin-8 by respiratory epithelial cells. These results support that MNP can effectively deliver SOAs to epithelial cells in vitro resulting in a significant biological effects. PMID:16918243

  6. Solid-state white light-emitting electrochemical cells using iridium-based cationic transition metal complexes.

    PubMed

    Su, Hai-Ching; Chen, Hsiao-Fan; Fang, Fu-Chuan; Liu, Chih-Che; Wu, Chung-Chih; Wong, Ken-Tsung; Liu, Yi-Hung; Peng, Shie-Ming

    2008-03-19

    White electroluminescent (EL) emission from single-layered solid-state light-emitting electrochemical cells (LECs) based on host-guest cationic iridium complexes has been successfully demonstrated. The devices show white EL spectra (Commission Internationale de l'Eclairage coordinates ranging from (x, y) = (0.45, 0.40) to (0.35, 0.39) at 2.9-3.3 V with high color rendering indices up to 80. Peak external quantum efficiency and peak power efficiency of the white LEC reach 4% and 7.8 lm/W, respectively. These results suggest that white LECs based on host-guest cationic transition metal complexes may be a promising alternative for solid-state lighting technologies. PMID:18302372

  7. A multiscale approach to modelling electrochemical processes occurring across the cell membrane with application to transmission of action potentials.

    PubMed

    Richardson, G

    2009-09-01

    By application of matched asymptotic expansions, a simplified partial differential equation (PDE) model for the dynamic electrochemical processes occurring in the vicinity of a membrane, as ions selectively permeate across it, is formally derived from the Poisson-Nernst-Planck equations of electrochemistry. It is demonstrated that this simplified model reduces itself, in the limit of a long thin axon, to the cable equation used by Hodgkin and Huxley to describe the propagation of action potentials in the unmyelinated squid giant axon. The asymptotic reduction from the simplified PDE model to the cable equation leads to insights that are not otherwise apparent; these include an explanation of why the squid giant axon attains a diameter in the region of 1 mm. The simplified PDE model has more general application than the Hodgkin-Huxley cable equation and can, e.g. be used to describe action potential propagation in myelinated axons and neuronal cell bodies. PMID:19273492

  8. Secondary pancreatic involvement by a diffuse large B-cell lymphoma presenting as acute pancreatitis.

    PubMed

    Saif, M-Wasif; Khubchandani, Sapna; Walczak, Marek

    2007-09-28

    Diffuse large B-cell lymphoma is the most common type of non-Hodgkin's lymphoma. More than 50% of patients have some site of extra-nodal involvement at diagnosis, including the gastrointestinal tract and bone marrow. However, a diffuse large B-cell lymphoma presenting as acute pancreatitis is rare. A 57-year-old female presented with abdominal pain and matted lymph nodes in her axilla. She was admitted with a diagnosis of acute pancreatitis. Abdominal computed tomography (CT) scan showed diffusely enlarged pancreas due to infiltrative neoplasm and peripancreatic lymphadenopathy. Biopsy of the axillary mass revealed a large B-cell lymphoma. The patient was classified as stage IV, based on the Ann Arbor Classification, and as having a high-risk lymphoma, based on the International Prognostic Index. She was started on chemotherapy with CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone). Within a week after chemotherapy, the patient's abdominal pain resolved. Follow-up CT scan of the abdomen revealed a marked decrease in the size of the pancreas and peripancreatic lymphadenopathy. A literature search revealed only seven cases of primary involvement of the pancreas in B-cell lymphoma presenting as acute pancreatitis. However, only one case of secondary pancreatic involvement by B-cell lymphoma presenting as acute pancreatitis has been published. Our case appears to be the second report of such a manifestation. Both cases responded well to chemotherapy. PMID:17828824

  9. Electrochemical investigation of lithium/potassium carbonate eutectic for application in modeling the molten carbonate fuel cell cathode. Final progress report

    SciTech Connect

    McCoy, L.; Schuman, M.

    1986-04-01

    A program involving the design, construction, and operation of a high-temperature cell equipped with a rotating gold disk electrode has been carried out with the objective of identifying and quantifying the principal oxide species present in molten LiKCO/sub 3/ electrolytes using electrochemical measurements. The dependence of the current on electrode rotational speed at 750 to 800/sup 0/C indicates that the data are typical of the convective/diffusive transport of an electroactive species from the bulk electrolyte. The reverse is true at 650/sup 0/C, where the current increases with an increasing voltage sweep rate but is little affected by the speed of electrode rotation. In the latter case, a current by chemical reaction occurring within the electrode boundary layer is indicated. The linear current-voltage increase observed at the lower temperature in the presence of about 20 mol % 0/sub 2/ has not been accounted for. Graphical analysis of the data taken with air and C/sub 2/ sparged electrolyte at 750 and 800/sup 0/C indicates the electroactive species to be the superoxide ion. Computer studies of the same data using regression analysis methodology indicate that the current may instead arise from the reduction of the peroxide ion concurrently with other electroactive material derived from secondary catalytic reactions or electrolyte impurities. Additional data will be required to support either conclusion with certainty. Detailed studies of the electrochemistry of the LiKCO/sub 3/ electrolyte over a broader range of temperatures and sparge gas compositions are recommended as a means of providing a second basis for identifying the electrode reactions. 29 refs., 47 figs., 3 tabs.

  10. Electrochemical photovoltaic cells based on n-GaAs and the triiodide/iodide redox couple in acetonitrile

    SciTech Connect

    Langmuir, M.E.; Parker, M.A.; Rauh, R.D.

    1982-08-01

    The electrochemical photovoltaic cell (EPC) based on n-GaAs and a CH/sub 3/CN, I/sub 3//sup -//I/sup -/ redox electrolyte was evaluated. Greater than 1MI/sup -/ was necessary to avoid concentration polarization at the photoanode above moderate illumination intensities. The charge separation at the illuminated n-GaAs/electrolyte interface was enhanced by adsorption of Se/sup ./ and Ru/sup +3/ or by complexing polymers such as polyvinyl pyrrolidone. In practical cells, a compromise is necessary between light absorption by I/sub 3//sup -/, and having sufficient I/sub 3//sup -/ to depolarize the counterelectrode. Best ''solar cell'' efficiency in the quiescent electrolyte under 53 mW/cm/sup 2/ irradiation was about 3.4% with V/sub oc/.0.60,i/sub sc/.9 mA/cm/sup 2/, and fill factor 0.34 with no corrections for solution absorbance or cell reflectance. 16 refs.

  11. Disposable electrochemical flow cells for catalytic adsorptive stripping voltammetry (CAdSV) at a bismuth film electrode (BiFE)

    PubMed Central

    Gharib Naseri, Nahid; Economou, Anastasios; Goddard, Nicholas J.; Fielden, Peter R.

    2008-01-01

    Catalytic adsorptive stripping voltammetry (CAdSV) has been demonstrated at a bismuth film electrode (BiFE) in an injection-moulded electrochemical micro-flow cell. The polystyrene three-electrode flow cell was fabricated with electrodes moulded from a conducting grade of polystyrene containing 40% carbon fibre, one of which was precoated with Ag to enable its use as an on-chip Ag/AgCl reference electrode. CAdSV of Co(II) and Ni(II) in the presence of dimethylglyoxime (DMG) with nitrite employed as the catalyst was performed in order to assess the performance of the flow cell with an in-line plated BiFE. The injection-moulded electrodes were found to be suitable substrates for the formation of BiFEs. Key parameters such as the plating solution matrix, plating flow rate, analysis flow rate, solution composition and square-wave parameters have been characterised and optimal conditions selected for successful and rapid analysis of Co(II) and Ni(II) at the ppb level. The analytical response was linear over the range 1 to 20 ppb and deoxygenation of the sample solution was not required. The successful coupling of a microfluidic flow cell with a BiFE, thereby forming a “mercury-free” AdSV flow analysis sensor, shows promise for industrial and in-the-field applications where inexpensive, compact, and robust instrumentation capable of low-volume analysis is required. PMID:18351328

  12. Performance Evaluation of Electrochem's PEM Fuel Cell Power Plant for NASA's 2nd Generation Reusable Launch Vehicle

    NASA Technical Reports Server (NTRS)

    Kimble, Michael C.; Hoberecht, Mark

    2003-01-01

    NASA's Next Generation Launch Technology (NGLT) program is being developed to meet national needs for civil and commercial space access with goals of reducing the launch costs, increasing the reliability, and reducing the maintenance and operating costs. To this end, NASA is considering an all- electric capability for NGLT vehicles requiring advanced electrical power generation technology at a nominal 20 kW level with peak power capabilities six times the nominal power. The proton exchange membrane (PEM) fuel cell has been identified as a viable candidate to supply this electrical power; however, several technology aspects need to be assessed. Electrochem, Inc., under contract to NASA, has developed a breadboard power generator to address these technical issues with the goal of maximizing the system reliability while minimizing the cost and system complexity. This breadboard generator operates with dry hydrogen and oxygen gas using eductors to recirculate the gases eliminating gas humidification and blowers from the system. Except for a coolant pump, the system design incorporates passive components allowing the fuel cell to readily follow a duty cycle profile and that may operate at high 6:1 peak power levels for 30 second durations. Performance data of the fuel cell stack along with system performance is presented to highlight the benefits of the fuel cell stack design and system design for NGLT vehicles.

  13. Symposium on Electrochemical and Thermal Modeling of Battery, Fuel Cell, and Photoenergy Conversion Systems, San Diego, CA, Oct. 20-22, 1986, Proceedings

    NASA Astrophysics Data System (ADS)

    Selman, J. Robert; Maru, Hans C.

    Papers are presented on modeling of the zinc chlorine battery, design modeling of zinc/bromine battery systems, the modeling of aluminum-air battery systems, and a point defect model for a nickel electrode structure. Also considered are the impedance of a tubular electrode under laminar flow, mathematical modeling of a LiAl/Cl2 cell with a gas diffusion Cl2 electrode, ultrahigh power batteries, and battery thermal modeling. Other topics include an Na/beta-alumina/NaAlCl4, Cl2/C circulating cell, leakage currents in electrochemical systems having common electrodes, modeling for CO poisoning of a fuel cell anode, electrochemical corrosion of carbonaceous materials, and electrolyte management in molten carbonate fuel cells.

  14. Method of forming a leak proof plasma sprayed interconnection layer on an electrode of an electrochemical cell

    DOEpatents

    Kuo, L.J.H.; Vora, S.D.

    1995-02-21

    A dense, substantially gas-tight, electrically conductive interconnection layer is formed on an electrode structure of an electrochemical cell by: (A) providing an electrode structure; (B) forming on a selected portion of the electrode surface, an interconnection layer having the general formula La{sub 1{minus}x}M{sub x}Cr{sub 1{minus}y}N{sub y}O{sub 3}, where M is a dopant selected from the group of Ca, Sr, Ba, and mixtures thereof, and where N is a dopant selected from the group of Mg, Co, Ni, Al, and mixtures thereof, and where x and y are each independently about 0.075--0.25, by thermally spraying, preferably plasma arc spraying, a flux added interconnection spray powder, preferably agglomerated, the flux added powder comprising flux particles, preferably including dopant, preferably (CaO){sub 12}(Al{sub 2}O{sub 3}){sub 7} flux particles including Ca and Al dopant, and LaCrO{sub 3} interconnection particles, preferably undoped LaCrO{sub 3}, to form a dense and substantially gas-tight interconnection material bonded to the electrode structure by a single plasma spraying step; and (C) heat treating the interconnection layer at from about 1,200 to 1,350 C to further densify and heal the micro-cracks and macro-cracks of the thermally sprayed interconnection layer. The result is a substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode structure. The electrode structure can be an air electrode, and a solid electrolyte layer can be applied to the unselected portion of the air electrode, and further a fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell for generation of electrical power. 4 figs.

  15. Synthesis and physical/electrochemical characterization of Pt/C nanocatalyst for polymer electrolyte fuel cells

    NASA Astrophysics Data System (ADS)

    Prabhuram, J.; Zhao, T. S.; Wong, C. W.; Guo, J. W.

    In the present study, 20 wt.% Pt/C nanocatalyst has been synthesized by the simple formic acid reduction method (FARM) in the organic solvent tetrahyrofuran (THF). Transmission electron microscope (TEM) and X-ray diffraction (XRD) analyses indicate the formation of well-dispersed Pt nanoparticles having sizes of around 3-4 nm on the Vulcan XC-72 carbon support. A comparison between two different synthetic approaches by using the FARM shows that the formation and dispersion of the Pt nanoparticles can be facilitated by the THF solvent and high surface area Vulcan XC-72 carbon support. The surface characterization of the Pt/C by X-ray photoelectron spectroscopy (XPS) reveals that 60.3% of Pt is present in its metallic state. Furthermore, the electrochemical characterization by the cyclic voltammetry (CV) demonstrates that the electrochemical active surface (EAS) area and methanol oxidation reaction of the Pt/C is respectively almost similar and slightly higher than that of the 20 wt.% Pt/C E-TEK catalyst.

  16. Studies of electrochemical performance of carbon supported Pt–Cu nanoparticles as anode catalysts for direct borohydride–hydrogen peroxide fuel cell

    Microsoft Academic Search

    Lanhua Yi; Benan Hu; Yunfeng Song; Xianyou Wang; Guishan Zou; Wei Yi

    2011-01-01

    Carbon supported Pt–Cu bimetallic nanoparticles are prepared by a modified NaBH4 reduction method in aqueous solution and used as the anode electrocatalyst of direct borohydride–hydrogen peroxide fuel cell (DBHFC). The physical and electrochemical properties of the as-prepared electrocatalysts are investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry (CV), chronoamperometry (CA), chronopotentiometry (CP) and fuel cell test. The

  17. Space Electrochemical Research and Technology

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The proceedings of NASA's third Space Electrochemical Research and Technology (SERT) conference are presented. The objective of the conference was to assess the present status and general thrust of research and development in those areas of electrochemical technology required to enable NASA missions in the next century. The conference provided a forum for the exchange of ideas and opinions of those actively involved in the field, in order to define new opportunities for the application of electrochemical processes in future NASA missions. Papers were presented in three technical areas: the electrochemical interface, the next generation in aerospace batteries and fuel cells, and electrochemistry for nonenergy storage applications.

  18. Change of electrochemical impedance spectra (EIS) with time during CO-poisoning of the Pt-anode in a membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Wagner, N.; Gülzow, E.

    This paper focuses on the electrochemical characterisation, e.g. current-voltage-measurement and time resolved electrochemical impedance spectroscopy (TREIS) of polymer electrolyte fuel cells (PEFCs) during operation of the fuel cell with oxygen and H 2+100 ppm CO respectively. Due to the poisoning effect of carbon monoxide, the system changes its state during the experiment. The reconstruction of quasi-causal impedance spectra was made by using enhanced numerical procedures. The reconstructed impedance spectra recorded at constant load, in galvanostatic mode of operation of the fuel cell show a strong time dependence and exhibit pseudo-inductive contributions at the low frequency part of the spectra which increase during the experiment. The analysis of the spectra suggests that the pseudo-inductive behaviour can be attributed to a surface relaxation process of the anode. Furthermore, the influence of the carbon monoxide on the electrochemical behaviour of the contaminated fuel cell may be interpreted by means of a Faraday impedance in addition with a potential-dependent hindrance of the charge transfer. Otherwise, the impedance spectra recorded during CO poisoning of the anode at constant cell voltage, in the potentiostatic mode of operation of the fuel cell, show also a strong time dependence, but no pseudo-inductive contribution in the low frequency part of the spectra.

  19. Ultrasound-assisted synthesis of Li-rich mesoporous LiMn2O4 nanospheres for enhancing the electrochemical performance in Li-ion secondary batteries.

    PubMed

    Kim, Jung Min; Lee, Gaehang; Kim, Byung Hoon; Huh, Yun Suk; Lee, Go-Woon; Kim, Hae Jin

    2012-05-01

    The hierarchically structured mesoporous LiMn(2)O(4) (LMO) nanospheres were synthesized using a template-free self-assembly process that was coupled with ultrasound (U). The ultrasound technique suggested here is very powerful for controlling an ordered nanostructure and improving crystallinity with large single-crystalline domains. Owing to the hierarchical mesoporous structure and high crystallinity, U-LMO provides an excellent rate capability and cycle stability with a capacity retention of more than 98% up to 50 cycles at a 0.2C rate. Here, we demonstrate that mesoporous U-LMO nanospheres were fabricated to enhance the electrochemical performance and protect it from structurally significant collapsing because of high crystallinity. PMID:22067553

  20. Synthesis and electrochemical properties of LiV3O8/PAn composite as a cathode material for lithium secondary batteries

    NASA Astrophysics Data System (ADS)

    Xie, Ling-Ling; Cao, Xiao-Yu; Zhang, Li-Xu; Dai, Zhong-Xu; Qu, Ling-Bo

    2013-03-01

    A LiV3O8/polyaniline (PAn) composite was prepared by the in-situ polymerization method assisted by sodium dodecyl sulfate and ammonium persulfate. The as-prepared powders were investigated by XRD, SEM, and galvanostatic discharge/charge analysis. It was found that the introduction of PAn to LiV3O8 can effectively buffer the mechanical stress and restrain the number of phase changes of composite material during the electrochemical cycling. Compared with pristine LiV3O8, LiV3O8/PAn composite maintains a reversible capacity of 212.1 mAh g-1 at the current density of 30 mA g-1 after 50 cycles, approximately 22.6%, much higher than the former.

  1. Electrochemical-Storage-Systems Program summary

    NASA Astrophysics Data System (ADS)

    Kwan, Q.

    1982-12-01

    A brief description of each contract and subcontract that was a part of the Electrochemical Energy Storage System (ECS) program through FY 1982 is provided. The work described covers electrochemical systems research, supporting research, electrochemical processes, and fuel cells for transportation, aqueous nonflow batteries, nonaqueous batteries, and battery testing.

  2. Electrochemical-Storage-Systems Program summary

    SciTech Connect

    Kwan, Q. (comp.)

    1982-12-01

    A brief description of each contract and subcontract that was a part of the Electrochemical Energy Storage System (ECS) program through FY 1982 is provided. The work described covers electrochemical systems research, supporting research, electrochemical processes, and fuel cells for transportation, aqueous nonflow batteries, nonaqueous batteries, and battery testing. (LEW)

  3. Secondary cell with orthorhombic alkali metal/manganese oxide phase active cathode material

    DOEpatents

    Doeff, Marca M. (Hayward, CA); Peng, Marcus Y. (Cupertino, CA); Ma, Yanping (Albany, CA); Visco, Steven J. (Berkeley, CA); DeJonghe, Lutgard C. (Lafayette, CA)

    1996-01-01

    An alkali metal manganese oxide secondary cell is disclosed which can provide a high rate of discharge, good cycling capabilities, good stability of the cathode material, high specific energy (energy per unit of weight) and high energy density (energy per unit volume). The active material in the anode is an alkali metal and the active material in the cathode comprises an orthorhombic alkali metal manganese oxide which undergoes intercalation and deintercalation without a change in phase, resulting in a substantially linear change in voltage with change in the state of charge of the cell. The active material in the cathode is an orthorhombic structure having the formula M.sub.x Z.sub.y Mn.sub.(1-y) O.sub.2, where M is an alkali metal; Z is a metal capable of substituting for manganese in the orthorhombic structure such as iron, cobalt or titanium; x ranges from about 0.2 in the fully charged state to about 0.75 in the fully discharged state, and y ranges from 0 to 60 atomic %. Preferably, the cell is constructed with a solid electrolyte, but a liquid or gelatinous electrolyte may also be used in the cell.

  4. Engineering secondary metabolism in maize cells by ectopic expression of transcription factors

    PubMed Central

    Grotewold, E; Chamberlin, M; Snook, M; Siame, B; Butler, L; Swenson, J; Maddock, S; Clair, GS; Bowen, B

    1998-01-01

    Manipulation of plant natural product biosynthesis through genetic engineering is an attractive but technically challenging goal. Here, we demonstrate that different secondary metabolites can be produced in cultured maize cells by ectopic expression of the appropriate regulatory genes. Cell lines engineered to express the maize transcriptional activators C1 and R accumulate two cyanidin derivatives, which are similar to the predominant anthocyanin found in differentiated plant tissues. In contrast, cell lines that express P accumulate various 3-deoxy flavonoids. Unexpectedly, P-expressing cells in culture also accumulate phenylpropanoids and green fluorescent compounds that are targeted to different subcellular compartments. Two endogenous biosynthetic genes (c2 and a1, encoding chalcone synthase and flavanone/dihydroflavonol reductase, respectively) are independently activated by ectopic expression of either P or C1/R, and there is a dose-response relationship between the transcript level of P and the degree to which c2 or a1 is expressed. Our results support a simple model showing how the gene encoding P may act as a quantitative trait locus controlling insecticidal C-glycosyl flavone level in maize silks, and they suggest how p1 might confer a selective advantage against insect predation in maize. PMID:9596632

  5. Clonal Architecture of Secondary Acute Myeloid Leukemia Defined by Single-Cell Sequencing

    PubMed Central

    Hughes, Andrew E. O.; Magrini, Vincent; Demeter, Ryan; Miller, Christopher A.; Fulton, Robert; Fulton, Lucinda L.; Eades, William C.; Elliott, Kevin; Heath, Sharon; Westervelt, Peter; Ding, Li; Conrad, Donald F.; White, Brian S.; Shao, Jin; Link, Daniel C.; DiPersio, John F.; Mardis, Elaine R.; Wilson, Richard K.; Ley, Timothy J.; Walter, Matthew J.; Graubert, Timothy A.

    2014-01-01

    Next-generation sequencing has been used to infer the clonality of heterogeneous tumor samples. These analyses yield specific predictions—the population frequency of individual clones, their genetic composition, and their evolutionary relationships—which we set out to test by sequencing individual cells from three subjects diagnosed with secondary acute myeloid leukemia, each of whom had been previously characterized by whole genome sequencing of unfractionated tumor samples. Single-cell mutation profiling strongly supported the clonal architecture implied by the analysis of bulk material. In addition, it resolved the clonal assignment of single nucleotide variants that had been initially ambiguous and identified areas of previously unappreciated complexity. Accordingly, we find that many of the key assumptions underlying the analysis of tumor clonality by deep sequencing of unfractionated material are valid. Furthermore, we illustrate a single-cell sequencing strategy for interrogating the clonal relationships among known variants that is cost-effective, scalable, and adaptable to the analysis of both hematopoietic and solid tumors, or any heterogeneous population of cells. PMID:25010716

  6. Origin, Maturation and Astroglial Transformation of Secondary Radial Glial Cells in the Developing Dentate Gyrus

    PubMed Central

    Brunne, Bianka; Zhao, Shanting; Derouiche, Amin; Herz, Joachim; May, Petra; Frotscher, Michael; Bock, Hans H.

    2010-01-01

    The dentate gyrus is a brain region where neurons are continuously born throughout life. In the adult, the role of its radial glia in neurogenesis has attracted much attention over the past years, however, little is known about the generation and differentiation of glial cells and their relationship to radial glia during the ontogenetic development of this brain structure. Here, we combine immunohistochemical phenotyping using antibodies against glial marker proteins with BrdU birthdating to characterize the development of the secondary radial glial scaffold in the dentate gyrus and its potential to differentiate into astrocytes. We demonstrate that the expression of BLBP, GLAST and GFAP characterizes immature differentiating cells confined to an astrocytic fate in the early postnatal dentate gyrus. Based on our studies we propose a model where immature astrocytes migrate radially through the granule cell layer to adopt their final positions in the molecular layer of the dentate gyrus. Time-lapse imaging of acute hippocampal slices from hGFAP-eGFP transgenic mice provide direct evidence for such a migration mode of differentiating astroglial cells in the developing dentate gyrus. PMID:20549747

  7. Preparation of Pt-Co nanoparticles by galvanostatic pulse electrochemical codeposition on in situ electrochemical reduced graphene nanoplates based carbon paper electrode for oxygen reduction reaction in proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Yaldagard, Maryam; Seghatoleslami, Naser; Jahanshahi, Mohsen

    2014-10-01

    Nanocomposite films of Pt-Co nanoparticles deposited on graphene nanoplate based gas diffusion layer electrode are fabricated via an electrochemical route involving a series of electrochemical process. Pt-Co nanoparticles of 11.37 nm in average size are prepared by galvanostatic codeposition in 0.5 M NaCl at PH of 2.5 at 300 mA cm-2 on the surface of in situ reduced graphene nanoplates on carbon paper. The topographical features, structure, morphology and composition of the prepared film samples are characterized by Atomic Force microscopy, Raman Spectroscopy, FTIR analysis, X-ray Diffraction, FESEM and EDS. At the same time, the catalytic activities of prepared electrodes for the oxygen reduction reaction are evaluated through cyclic voltammetry, linear sweep voltammetry and chronoamperometry and electrochemical impedance spectroscopy measurements. Raman spectroscopy measurements confirmed the graphitic structure of the produced graphene nanoplates. The nanoparticles in the film were observed to be uniform spherical objects and well distributed. Catalytic properties of Pt-Co/GNP/GDL electrode were compared with Pt/C/GDL using half cell polarization measurements based on both mass activity and specific activity. The as prepared Pt-Co/GNP/GDL electrode exhibits high catalytic activity for the ORR, which may be attributed to structural changes caused by alloying and the high specific surface area of graphene nanoplates catalyst support. The mass activity peak current is found to be as high as 728.25 mA mgPt-1.

  8. Electrochemical deposition of ZnO nanorods on transparent reduced graphene oxide electrodes for hybrid solar cells.

    PubMed

    Yin, Zongyou; Wu, Shixin; Zhou, Xiaozhu; Huang, Xiao; Zhang, Qichun; Boey, Freddy; Zhang, Hua

    2010-01-01

    Monocrystalline ZnO nanorods (NRs) with high donor concentration are electrochemically deposited on highly conductive reduced graphene oxide (rGO) films on quartz. The film thickness, optical transmittance, sheet resistance, and roughness of rGO films are systematically studied. The obtained ZnO NRs on rGO films are characterized by X-ray diffraction, transmission electron microscopy, photoluminescence, and Raman spectra. As a proof-of-concept application, the obtained ZnO NRs on rGO are used to fabricate inorganic-organic hybrid solar cells with layered structure of quartz/rGO/ZnO NR/poly(3-hexylthiophene)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (P3HT/PEDOT:PSS)/Au. The observed power conversion efficiency (PCE, eta), approximately 0.31%, is higher than that reported in previous solar cells by using graphene films as electrodes. These results clearly demonstrate that rGO films with a higher conductivity have a smaller work function and show a better performance in the fabricated solar cells. PMID:20039255

  9. Electrochemical Performance and Stability of the Cathode for Solid Oxide Fuel Cells IV. On the Ohmic loss in anode supported button cells with LSM or LSCF cathodes

    SciTech Connect

    Lu, Zigui; Zhou, Xiao Dong; Templeton, Jared W.; Stevenson, Jeffry W.

    2010-05-08

    Anode-supported solid oxide fuel cells (SOFC) with a variety of YSZ electrolyte thicknesses were fabricated by tape casting and lamination. The preparation of the YSZ electrolyte tapes with various thicknesses was accomplished by using doctor blades with different gaps between the precision machined, polished blade and the casting surface. The green tape was cut into discs, sintered at 1385°C for 2 h, and subsequently creep-flattened at 1350°C for 2 h. Either LSCF with an SDC interlayer or LSM+YSZ composite was used as the cathode material for the fuel cells. The ohmic resistances of these anode-supported fuel cells were characterized by electrochemical impedance spectroscopy at temperatures from 500°C to 750°C. A linear relationship was found between the ohmic resistance of the fuel cell and the YSZ electrolyte thickness at all the measuring temperatures for both LSCF and LSM+YSZ cathode fuel cells. The ionic conductivities of the YSZ electrolyte, derived for the fuel cells with LSM+YSZ or LSCF cathodes, were independent of the cathode material and cell configuration. The ionic conductivities of the YSZ electrolyte was slightly lower than that of the bulk material, possibly due to Ni-doping into the electrolyte. The fuel cell with a SDC interlayer and LSCF cathode showed larger intercept resistance than the fuel cell with LSM+YSZ cathode, which was possibly due to the imperfect contact between the SDC interlayer and the YSZ electrolyte and the migration of Zr into the SDC interlayer to form an insulating solid solution during cell fabrication. Calculations of the contribution of the YSZ electrolyte to the total ohmic resistance showed that YSZ was still a satisfactory electrolyte at temperatures above 650°C. Explorations should be directed to reduce the intercept resistance to achieve significant improvement in cell performance.

  10. Unit-cell intergrowth of pyrochlore and hexagonal tungsten bronze structures in secondary tungsten minerals

    SciTech Connect

    Grey, Ian E. [CSIRO Minerals, Box 312, Clayton South, Vic. 3169 (Australia)]. E-mail: ian.grey@csiro.au; Birch, William D. [Geosciences Department, Museum Victoria, GPO Box 666, Melbourne, Vic. 3001 (Australia); Bougerol, Catherine [Equipe CEA-CNRS NPSC SP2M/DRFMC/CEA, 17 rue des Martyrs, 38054 Grenoble (France); Mills, Stuart J. [CSIRO Minerals, Box 312, Clayton South, Vic. 3169 (Australia); Geosciences Department, Museum Victoria, GPO Box 666, Melbourne, Vic. 3001 (Australia)

    2006-12-15

    Structural relations between secondary tungsten minerals with general composition A{sub x}[(W,Fe)(O,OH){sub 3}]{sub .y}H{sub 2}O are described. Phyllotungstite (A=predominantly Ca) is hexagonal, a=7.31(3)A, c=19.55(1)A, space group P6{sub 3}/mmc. Pittongite, a new secondary tungsten mineral from a wolframite deposit near Pittong in Victoria, southeastern Australia (A=predominantly Na) is hexagonal, a=7.286(1)A, c=50.49(1)A, space group P-6m2. The structures of both minerals can be described as unit-cell scale intergrowths of (111){sub py} pyrochlore slabs with pairs of hexagonal tungsten bronze (HTB) layers. In phyllotungstite, the (111){sub py} blocks have the same thickness, 6A, whereas pittongite contains pyrochlore blocks of two different thicknesses, 6 and 12A. The structures can alternatively be described in terms of chemical twinning of the pyrochlore structure on (111){sub py} oxygen planes. At the chemical twin planes, pairs of HTB layers are corner connected as in hexagonal WO{sub 3}.

  11. Optical and electrochemical detection techniques for cell-based microfluidic systems

    Microsoft Academic Search

    Changqing Yi; Qi Zhang; Cheuk-Wing Li; Jun Yang; Jianlong Zhao; Mengsu Yang

    2006-01-01

    The ability to fabricate microfluidic systems with complex structures and with compatible dimensions between the microfluidics\\u000a and biological cells have attracted significant attention in the development of microchips for analyzing the biophysical and\\u000a biochemical functions of cells. Just as cell-based microfluidics have become a versatile tool for biosensing, diagnostics,\\u000a drug screening and biological research, detector modules for cell-based microfluidics have

  12. The electrochemical generation of useful chemical species from lunar materials

    NASA Technical Reports Server (NTRS)

    Tsai, Kan J.; Kuchynka, Daniel J.; Sammells, Anthony F.

    1989-01-01

    The current status of work on an electrochemical technology for the simultaneous generation of oxygen and lithium from a Li2O containing molten salt (Li2O-LiCl-LiF) is discussed. The electrochemical cell utilizes an oxygen vacancy conducting solid electrolyte, yttria-stabilized zirconia, to effect separation between the oxygen evolving and lithium reduction half-cell reactions. The cell, which operates at 700 to 800 C, possesses rapid electrode kinetics at the lithium-alloy electrode with exchange current density values being greater than 60 mA/sq cm, showing high reversibility for this reaction. When used in the electrolytic mode, lithium produced at the negative electrode would be continuously removed from the cell for later use (under lunar conditions) as an easily storable reducting agent (compared to H2) for the chemical refining of lunar ores via the general reaction: 2Li + MO yields Li2O + M where MO represents a lunar ore. Emphasis to this time has been on the simulated lunar ore ilmenite (FeTiO3), which we have found becomes chemically reduced by Li at 432 C. Furthermore, both Fe2O3 and TiO2 have been reduced by Li to give the corresponding metal. This electrochemical approach provides a convenient route for producing metals under lunar conditions and oxygen for the continuous maintenance of human habitats on the Moon's surface. Because of the high reversibility of this electrochemical system, it has also formed the basis for the lithium-oxygen secondary battery. This secondary lithium-oxygen battery system posses the highest theoretical energy density yet investigated.

  13. Microstructures and electrochemical properties of a SiO1.39-C composite for a lithium-ion secondary battery

    NASA Astrophysics Data System (ADS)

    Cheon, Jung Hoon; Jang, Bo Yun; Kim, Jun Soo; Lee, Jin Seok; Cho, Churl Hee

    2013-04-01

    SiO1.39 nanoparticles synthesized by using an evaporation and condensation process were composited with phenol resin and conducting carbon (C), and their microstructures and electrochemical properties were investigated. A dense, micro-sized SiO1.39-C composite was synthesized to prevent capacity fading of the SiO x nanoparticles. To densify and coarsen this composite, we carried out pelletizing, annealing and crushing of the sample. The electrical conductivity was also improved by the composition without any structural change. Crushed particles were used as an anode material for a Li-ion battery, and its cyclic performance was evaluated. By composition, the coulombic efficiency was observed to increase from 93.6 to 97.5% at the 5 th cycle, and it continued increasing with each additional cycle. For the composite annealed at 1,000 °C in a 4-vol.% H2/Ar atmosphere, the specific capacity and the coulombic efficiency at the 20 th cycle were measured as 426 mAhg-1 and 99.7%, respectively.

  14. Immobilization of Enzymes by Electrochemical and Chemical Oxidative Polymerization of L-DOPA to Fabricate Amperometric Biosensors and Biofuel Cells.

    PubMed

    Dai, Mengzhen; Sun, Lingen; Chao, Long; Tan, Yueming; Fu, Yingchun; Chen, Chao; Xie, Qingji

    2015-05-27

    Electrochemical/chemical oxidative synthesis and biosensing/biofuel cell applications of poly(L-DOPA) (PD) are studied versus polydopamine (PDA) as a recent hotspot biomaterial. The enzyme electrode developed by coelectrodeposition of PD and glucose oxidase (GOx), uricase, or tyrosinase shows biosensing performance superior to that of the corresponding PDA-based enzyme electrode. The chemical oxidative polymerization of L-DOPA (PDC) by NaAuCl4 in GOx-containing neutral aqueous solution is used to immobilize GOx and gold nanoparticles (AuNPs). The thus-prepared chitosan (CS)/GOx-PDC-AuNPs/Auplate/Au electrode working in the first-generation biosensing mode responds linearly to glucose concentration with a sensitivity of 152 ?A mM(-1) cm(-2), which is larger than those of the CS/GOx-PDAC-AuNPs/Auplate/Au electrode, the CS/GOx-poly(3-anilineboronic acid) (PABA)-AuNPs/Auplate/Au electrode, and the most reported GOx-based enzyme electrodes. This PDC-based enzyme electrode also works well in the second-generation biosensing mode and as an excellent bioanode in biofuel cell construction, probably because PD as an amino acid polymer has the higher biocompatibility and the more favorable affinity to the enzyme than PDA. The PD material of great convenience in synthesis, outstanding biocompatibility for preparing high-performance bionanocomposites, and strong capability of multifunctional coatings on many surfaces may find wide applications in diversified fields including biotechnology and surface-coating. PMID:25938891

  15. Position dependent analysis of membrane electrode assembly degradation of a direct methanol fuel cell via electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Hartmann, Peter; Zamel, Nada; Gerteisen, Dietmar

    2013-11-01

    The performance of a direct methanol fuel cell MEA degraded during an operational period of more than 3000 h in a stack is locally examined using electrochemical impedance spectroscopy. Therefore, after disassembling the MEA is cut into small pieces and analyzed in a 1 cm2 test cell. Using a reference electrode, we were capable of measuring the anode and cathode spectra separately. The spectra of the segments at different positions do not follow a specified trend from methanol inlet to outlet of the stack flow field. The anode spectra were analyzed with an equivalent circuit simulation. The conductance of the charge transfer was found to increase with current density up to a point where a raising limitation process of the complex methanol oxidation dominates, which is not a bottleneck at low current density. Further, an increase of the double layer capacitance with current density was observed. The diffusion resistance was calculated as an effective diffusion coefficient in the order of 10-10 m2 s-1; implying that the diffusion limitation is not the bulk diffusion in the backing layer. Finally, the degree of poisoning of the catalysts by carbon monoxide was measured as a pseudo inductive arc and decreases with increasing current.

  16. Qualification testing of secondary sterilizable silver-zinc cells for use in the Jupiter atmospheric entry probe

    NASA Technical Reports Server (NTRS)

    Manzo, M. A.

    1981-01-01

    A series of qualification tests were run on the secondary, sterilizable silver oxide - zinc cell developed at the NASA Lewis Research Center to determine if the cell was capable of providing mission power requirements for the Jupiter atmospheric entry probe. The cells were tested for their ability to survive radiation at the levels predicted for the Jovian atmosphere with no loss of performance. Cell performance was evaluated under various temperature and loading conditions, and the cells were tested under various environmental conditions related to launch and to deceleration into the Jovian atmosphere. The cell performed acceptably except under the required loading at low temperatures. The cell was redesigned to improve low-temperature performance and energy density. The modified cells improved performance at all temperatures. Results of testing cells of both the original and modified designs are discussed.

  17. The dual functions of WLIM1a in cell elongation and secondary wall formation in developing cotton fibers.

    PubMed

    Han, Li-Bo; Li, Yuan-Bao; Wang, Hai-Yun; Wu, Xiao-Min; Li, Chun-Li; Luo, Ming; Wu, Shen-Jie; Kong, Zhao-Sheng; Pei, Yan; Jiao, Gai-Li; Xia, Gui-Xian

    2013-11-01

    LIN-11, Isl1 and MEC-3 (LIM)-domain proteins play pivotal roles in a variety of cellular processes in animals, but plant LIM functions remain largely unexplored. Here, we demonstrate dual roles of the WLIM1a gene in fiber development in upland cotton (Gossypium hirsutum). WLIM1a is preferentially expressed during the elongation and secondary wall synthesis stages in developing fibers. Overexpression of WLIM1a in cotton led to significant changes in fiber length and secondary wall structure. Compared with the wild type, fibers of WLIM1a-overexpressing plants grew longer and formed a thinner and more compact secondary cell wall, which contributed to improved fiber strength and fineness. Functional studies demonstrated that (1) WLIM1a acts as an actin bundler to facilitate elongation of fiber cells and (2) WLIM1a also functions as a transcription factor to activate expression of Phe ammonia lyase-box genes involved in phenylpropanoid biosynthesis to build up the secondary cell wall. WLIM1a localizes in the cytosol and nucleus and moves into the nucleus in response to hydrogen peroxide. Taken together, these results demonstrate that WLIM1a has dual roles in cotton fiber development, elongation, and secondary wall formation. Moreover, our study shows that lignin/lignin-like phenolics may substantially affect cotton fiber quality; this finding may guide cotton breeding for improved fiber traits. PMID:24220634

  18. Electrochemical state and internal variables estimation using a reduced-order physics-based model of a lithium-ion cell and an extended Kalman filter

    NASA Astrophysics Data System (ADS)

    Stetzel, Kirk D.; Aldrich, Lukas L.; Trimboli, M. Scott; Plett, Gregory L.

    2015-03-01

    This paper addresses the problem of estimating the present value of electrochemical internal variables in a lithium-ion cell in real time, using readily available measurements of cell voltage, current, and temperature. The variables that can be estimated include any desired set of reaction flux and solid and electrolyte potentials and concentrations at any set of one-dimensional spatial locations, in addition to more standard quantities such as state of charge. The method uses an extended Kalman filter along with a one-dimensional physics-based reduced-order model of cell dynamics. Simulations show excellent and robust predictions having dependable error bounds for most internal variables.

  19. Solid oxide electrochemical reactor science

    Microsoft Academic Search

    Neal P. Sullivan; Ellen Beth Stechel; Connor J. Moyer; Andrea Ambrosini; Robert J. Key

    2010-01-01

    Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful information to their continued development. This LDRD involved a collaboration between Sandia and the Colorado School of Mines (CSM) ins solid-oxide electrochemical reactors targeted at solid

  20. Bioelectrochemical interface engineering: toward the fabrication of electrochemical biosensors, biofuel cells, and self-powered logic biosensors.

    PubMed

    Zhou, Ming; Dong, Shaojun

    2011-11-15

    Over the past decade, researchers have devoted considerable attention to the integration of living organisms with electronic elements to yield bioelectronic devices. Not only is the integration of DNA, enzymes, or whole cells with electronics of scientific interest, but it has many versatile potential applications. Researchers are using these ideas to fabricate biosensors for analytical applications and to assemble biofuel cells (BFCs) and biomolecule-based devices. Other research efforts include the development of biocomputing systems for information processing. In this Account, we focus on our recent progress in engineering at the bioelectrochemical interface (BECI) for the rational design and construction of important bioelectronic devices, ranging from electrochemical (EC-) biosensors to BFCs, and self-powered logic biosensors. Hydrogels and sol-gels provide attractive materials for the immobilization of enzymes because they make EC-enzyme biosensors stable and even functional in extreme environments. We use a layer-by-layer (LBL) self-assembly technique to fabricate multicomponent thin films on the BECI at the nanometer scale. Additionally, we demonstrate how carbon nanomaterials have paved the way for new and improved EC-enzyme biosensors. In addition to the widely reported BECI-based electrochemical impedance spectroscopy (EIS)-type aptasensors, we integrate the LBL technique with our previously developed "solid-state probe" technique for redox probes immobilization on electrode surfaces to design and fabricate BECI-based differential pulse voltammetry (DPV)-type aptasensors. BFCs can directly harvest energy from ambient biofuels as green energy sources, which could lead to their application as simple, flexible, and portable power sources. Porous materials provide favorable microenvironments for enzyme immobilization, which can enhance BFC power output. Furthermore, by introducing aptamer-based logic systems to BFCs, such systems could be applied as self-powered and intelligent aptasensors for the logic detection. We have developed biocomputing keypad lock security systems which can be also used for intelligent medical diagnostics. BECI engineering provides a simple but effective approach toward the design and fabrication of EC-biosensors, BFCs, and self-powered logic biosensors, which will make essential contributions in the development of creative and practical bioelectronic devices. The exploration of novel interface engineering applications and the creation of new fabrication concepts or methods merit further attention. PMID:21812435

  1. Intravascular large B-cell lymphoma secondary to lymphoplasmacytic lymphoma: a case report and review of literature with clonality analysis

    PubMed Central

    Tanaka, Yosuke; Kobayashi, Yukio; Maeshima, Akiko Miyagi; Oh, Sung Yong; Nomoto, Junko; Fukuhara, Suguru; Kitahara, Hideaki; Munakata, Wataru; Suzuki, Tatsuya; Maruyama, Dai; Tobinai, Kensei

    2015-01-01

    Intravascular large B-cell lymphoma (IVLBCL) can be a fatal malignancy mainly because of difficulty in early detection. Due to the lack of specific clinical manifestations, early detection of IVLBCL remains a challenge, especially in the presence of comorbidities. Lymphoplasmacytic lymphoma (LPL) is an indolent B-cell lymphoma accompanied by monoclonal immunoglobulin M protein in most patients, and known to be associated with high risk of secondary hematological malignancies. Here, we report a patient who developed IVLBCL during treatment for LPL that presented a diagnostic challenge. Rearrangement analysis of the immunoglobulin heavy chain revealed the different clonal origins of two lymphomas, implying a predisposition of LPL to develop unrelated secondary lymphoma. Secondary lymphoma including IVLBCL during the treatment for LPL deserves consideration in order to facilitate early diagnosis and intervention.

  2. Intravascular large B-cell lymphoma secondary to lymphoplasmacytic lymphoma: a case report and review of literature with clonality analysis.

    PubMed

    Tanaka, Yosuke; Kobayashi, Yukio; Maeshima, Akiko Miyagi; Oh, Sung Yong; Nomoto, Junko; Fukuhara, Suguru; Kitahara, Hideaki; Munakata, Wataru; Suzuki, Tatsuya; Maruyama, Dai; Tobinai, Kensei

    2015-01-01

    Intravascular large B-cell lymphoma (IVLBCL) can be a fatal malignancy mainly because of difficulty in early detection. Due to the lack of specific clinical manifestations, early detection of IVLBCL remains a challenge, especially in the presence of comorbidities. Lymphoplasmacytic lymphoma (LPL) is an indolent B-cell lymphoma accompanied by monoclonal immunoglobulin M protein in most patients, and known to be associated with high risk of secondary hematological malignancies. Here, we report a patient who developed IVLBCL during treatment for LPL that presented a diagnostic challenge. Rearrangement analysis of the immunoglobulin heavy chain revealed the different clonal origins of two lymphomas, implying a predisposition of LPL to develop unrelated secondary lymphoma. Secondary lymphoma including IVLBCL during the treatment for LPL deserves consideration in order to facilitate early diagnosis and intervention. PMID:26045864

  3. Evaluation Program for Secondary Spacecraft Cells: Synchronous Orbit Testing of Sealed Nickel Cadmium Cells

    NASA Technical Reports Server (NTRS)

    Harkness, J. D.

    1977-01-01

    Performance data concerning sealed nickel-cadmium cells operating under a synchronous orbit regime are presented. A space satellite maintaining a position over a fixed point on earth as the earth rotates on its axis and revolves about the sun was simulated. Results include: (1) exposure to synchronous orbit testing at a temperature of 40 C yields less than 6 years of life; (2) performance at -20 C presents a low capacity problem; (3) the capacity check, performed at the middle of each show period, provides a temporary red reconditioning effect on the cells in that the end-of-discharge voltages are higher, for approximately 7 to 10 days, following the capacity check than they were 7 to 10 days prior to the capacity check; (4) all the test packs at -20 C and 40 C have either failed or were discontinued because of low capacity; and (5) test packs at temperatures of 0 C and 10 C have delivered the best capacity during life and packs tested at 20 C showed better life capability than packs tested at -20 C and 40 C.

  4. Electrochemical model of the integrated planar solid oxide fuel cell (IP-SOFC)

    Microsoft Academic Search

    Paola Costamagna; Azra Selimovic; Marco Del Borghi; Gerry Agnew

    2004-01-01

    The Integrated Planar Solid Oxide Fuel Cell (IP-SOFC) is an innovative fuel cell concept which is substantially a cross between tubular and planar geometries, seeking to borrow thermal compliance properties from the former and low cost component fabrication and short current paths from the latter. In this study, a simulation model for the IP-SOFC is presented, with particular highlight on

  5. Semiconductor liquid junction solar cells - Efficiency, electrochemical stability, and surface preparation

    Microsoft Academic Search

    B. Miller; A. Heller

    1977-01-01

    A review is presented of investigations which have been conducted to find examples of regenerative semiconductor-liquid junction cells with respectable solar conversion efficiencies and a promise of stability. An outline is provided of directions for reducing the cost of the semiconductor member of the cell. Attention is also given to studies which have been carried out to obtain information regarding

  6. DIRECT ELECTROCHEMICAL POWER GENERATION FROM CARBON IN FUEL CELLS WITH MOLTEN HYDROXIDE ELECTROLYTE

    Microsoft Academic Search

    Strahinja Zecevic; Edward M. Patton; Parviz Parhami

    2005-01-01

    Historically, despite its compelling cost and performance advantages, the use of a molten metal hydroxide electrolyte has been ignored by direct carbon fuel cell (DCFC) researchers, primarily due to the potential for formation of carbonate salt in the cell. This article describes the electrochemistry of a patented medium-temperature DCFC based on a molten hydroxide electrolyte, which overcomes the historical carbonate

  7. Optimization of electrochemical hydride generation in a miniaturized electrolytic flow cell coupled to microwave-induced plasma atomic emission spectrometry for the determination of selenium

    Microsoft Academic Search

    S. Schermer; L. Jurica; J. Paumard; E. Beinrohr; F.-M. Matysik; J. Broekaert

    2001-01-01

    The optimization of a continuous flow system for electrochemical hydride generation coupled to microwave-induced plasma atomic emission spectrometry (MIP-AES) for the determination of Se is presented. A small electrolytic cell with a porous glassy carbon working electrode was used for hydride generation. When using an Ar MIP operated in a TE101 cavity a detection limit of 0.6 ng mL-1 (3C)

  8. Integrated function of microbial fuel cell (MFC) as bio-electrochemical treatment system associated with bioelectricity generation under higher substrate load

    Microsoft Academic Search

    S. Venkata Mohan; S. Veer Raghavulu; Dinakar Peri; P. N. Sarma

    2009-01-01

    Function of microbial fuel cell (MFC) as bio-electrochemical treatment system in concurrence with power generation was evaluated with composite chemical wastewater at high loading conditions (18.6gCOD\\/l; 56.8gTDS\\/l). Two dual chambered MFCs [non-catalyzed graphite electrodes; mediatorless anode] were studied separately with aerated and potassium ferricyanide catholytes under similar anodic operating conditions [mixed consortia; pH 6]. Marked improvement in power output was

  9. Surface science and electrochemical studies of metal-modified carbides for fuel cells and hydrogen production

    NASA Astrophysics Data System (ADS)

    Kelly, Thomas Glenn

    Carbides of the early transition metals have emerged as low-cost catalysts that are active for a wide range of reactions. The surface chemistry of carbides can be altered by modifying the surface with small amounts of admetals. These metal-modified carbides can be effective replacements for Pt-based bimetallic systems, which suffer from the drawbacks of high cost and low thermal stability. In this dissertation, metal-modified carbides were studied for reactions with applications to renewable energy technologies. It is demonstrated that metal-modified carbides possess high activity for alcohol reforming and electrochemical hydrogen production. First, the surface chemistry of carbides towards alcohol decomposition is studied using density functional theory (DFT) and surface science experiments. The Vienna Ab initio Simulation Package (VASP) was used to calculate the binding energies of alcohols and decomposition intermediates on metal-modified carbides. The calculated binding energies were then correlated to reforming activity determined experimentally using temperature programmed desorption (TPD). In the case of methanol decomposition, it was found that tungsten monocarbide (WC) selectively cleaved the C-O bond to produce methane. Upon modifying the surface with a single layer of metal such as Ni, Pt, or Rh, the selectivity shifted towards scission of the C-H bonds while leaving the C-O bond intact, producing carbon monoxide (CO) and H2. High resolution energy loss spectroscopy (HREELS) was used to examine the bond breaking sequence as a function of temperature. From HREELS, it was shown that the surfaces followed an activity trend of Rh > Ni > Pt. The Au-modified WC surface possessed too low of a methanol binding energy, and molecular desorption of methanol was the most favorable pathway on this surface. Next, the ability of Rh-modified WC to break the C-C bond of C2 and C3 alcohols was demonstrated. HREELS showed that ethanol decomposed through an acetaldehyde intermediate on Rh/WC, and that the C-C bond was broken by 200 K. Finally, the suitability of metal-modified molybdenum carbide (Mo2C) as an ethanol decomposition catalyst was studied. A new reaction pathway of partial dehydrogenation to an acetaldehyde product was achieved by using Cu as an admetal. The second section of this dissertation was the study of metal-modified carbides for electrochemical hydrogen evolution. Previously, DFT calculations had predicted a similar hydrogen binding energy (HBE) between Pd-modified carbides and bulk Pd. Linear sweep voltammograms (LSV) demonstrated that Pd-modified WC and Mo2C possessed hydrogen evolution activity orders of magnitude greater than the bare carbides. The long-term stability of these surfaces under operating conditions was also examined. A two-hour chronopotentiometry experiment was performed, after which x-ray photoelectron spectroscopy (XPS) found that negligible loss of the Pd overlayer occurred. As an extension of this work, a DFT study was performed for several admetal/Mo2C combinations. It was shown that the HBE of these surfaces mostly correlated with the pure metal HBE. Some of these combinations were tested experimentally, but were unstable in the acidic electrolyte.

  10. Influence of high energy electrons and protons on secondary electron emission of cover glasses for space solar cells

    Microsoft Academic Search

    S. Kawakita; M. Imaizumi; M. Takahashi; S. Matsuda; S. Michizono; Y. Saito

    2002-01-01

    We measured the secondary electron emission (SEE) of cover glasses for space solar cells by beam blanking scanning electron microscopy (BBSEM) with a Faraday cup. The SEE yield of the cover glass is very important for analyzing the charge profile of the satellite. We observed the SEE of a cover glass coated with ZrO2. This cover glass was chosen for

  11. Synthesis and electrochemical performance of La0.7Sr0.3Co1-xFexO3 catalysts for zinc air secondary batteries

    NASA Astrophysics Data System (ADS)

    Ahn, Seyoung; Kim, Ketack; Kim, Hyunsoo; Nam, Sangyong; Eom, Seungwook

    2010-05-01

    We prepared La0.7Sr0.3Co1-xFexO3 (x=0.1-0.4) catalysts for a zinc air battery by using the citrate method under controlled pH. The prepared precursor powder was heat treated at the calcination temperature of 700 °C and examined for the optimum structure of the cathode. The structure and performance of the catalysts were examined by x-ray diffraction and a scanning electron microscope. The air electrode was prepared by blending the catalyst, Vulcan XC-72R (carbon black), and (polytetrafluoroethylene PTFE) suspension. The oxygen reduction reaction and the oxygen evolution reaction were examined by linear sweep voltammetry. The results showed that La0.7Sr0.3Co0.7Fe0.3O3 (LSCF0.7) is an excellent catalyst for the zinc air secondary battery.

  12. Electrochemical Techniques

    SciTech Connect

    Chen, Gang; Lin, Yuehe

    2008-07-20

    Sensitive and selective detection techniques are of crucial importance for capillary electrophoresis (CE), microfluidic chips, and other microfluidic systems. Electrochemical detectors have attracted considerable interest for microfluidic systems with features that include high sensitivity, inherent miniaturization of both the detection and control instrumentation, low cost and power demands, and high compatibility with microfabrication technology. The commonly used electrochemical detectors can be classified into three general modes: conductimetry, potentiometry, and amperometry.

  13. Electrochemical Partial Oxidation of Methane in Solid Oxide Fuel Cells: Effect of Anode Reforming Activity

    Microsoft Academic Search

    Manoj R. Pillai; David M. Bierschenk; Scott A. Barnett

    2008-01-01

    Direct-methane solid oxide fuel cells were used to produce electricity and syngas. During initial operation at 750 °C, the\\u000a cells produced 0.9 W\\/cm2 and ?90% methane conversion to syngas at a rate of 30 sccm\\/cm2. However, the methane conversion decreased continuously over the first 30–40 h of operation, even though the solid oxide\\u000a fuel cells (SOFC) electrical performance was stable. An additional catalyst layer

  14. Cross-Reactivity and Expansion of Dengue-Specific T cells During Acute Primary and Secondary Infections in Humans

    PubMed Central

    Friberg, Heather; Bashyam, Hema; Toyosaki-Maeda, Tomoko; Potts, James A.; Greenough, Thomas; Kalayanarooj, Siripen; Gibbons, Robert V.; Nisalak, Ananda; Srikiatkhachorn, Anon; Green, Sharone; Stephens, Henry A. F.; Rothman, Alan L.; Mathew, Anuja

    2011-01-01

    Serotype-cross-reactive memory T cells responding to secondary dengue virus (DENV) infection are thought to contribute to disease. However, epitope-specific T cell responses have not been thoroughly compared between subjects with primary versus secondary DENV infection. We studied CD8+ T cells specific for the HLA-A*1101-restricted NS3133 epitope in a cohort of A11+ DENV-infected patients throughout acute illness and convalescence. We compared the expansion, serotype-cross-reactivity, and activation of these cells in PBMC from patients experiencing primary or secondary infection and mild or severe disease by flow cytometry. Our results show expansion and activation of DENV-specific CD8+ T cells during acute infection, which are predominantly serotype-cross-reactive regardless of DENV infection history. These data confirm marked T cell activation and serotype-cross-reactivity during the febrile phase of dengue; however, A11-NS3133-specific responses did not correlate with prior antigenic exposure or current disease severity. PMID:22355570

  15. Arabidopsis NMD3 Is Required for Nuclear Export of 60S Ribosomal Subunits and Affects Secondary Cell Wall Thickening

    PubMed Central

    Chen, Mei-Qin; Zhang, Ai-Hong; Zhang, Quan; Zhang, Bao-Cai; Nan, Jie; Li, Xia; Liu, Na; Qu, Hong; Lu, Cong-Ming; Sudmorgen; Zhou, Yi-Hua; Xu, Zhi-Hong; Bai, Shu-Nong

    2012-01-01

    NMD3 is required for nuclear export of the 60S ribosomal subunit in yeast and vertebrate cells, but no corresponding function of NMD3 has been reported in plants. Here we report that Arabidopsis thaliana NMD3 (AtNMD3) showed a similar function in the nuclear export of the 60S ribosomal subunit. Interference with AtNMD3 function by overexpressing a truncated dominant negative form of the protein lacking the nuclear export signal sequence caused retainment of the 60S ribosomal subunits in the nuclei. More interestingly, the transgenic Arabidopsis with dominant negative interference of AtNMD3 function showed a striking failure of secondary cell wall thickening, consistent with the altered expression of related genes and composition of cell wall components. Observation of a significant decrease of rough endoplasmic reticulum (RER) in the differentiating interfascicular fiber cells of the transgenic plant stems suggested a link between the defective nuclear export of 60S ribosomal subunits and the abnormal formation of the secondary cell wall. These findings not only clarified the evolutionary conservation of NMD3 functions in the nuclear export of 60S ribosomal subunits in yeast, animals and plants, but also revealed a new facet of the regulatory mechanism underlying secondary cell wall thickening in Arabidopsis. This new facet is that the nuclear export of 60S ribosomal subunits and the formation of RER may play regulatory roles in coordinating protein synthesis in cytoplasm and transcription in nuclei. PMID:22558264

  16. Breakthrough Flow Battery Cell Stack: Transformative Electrochemical Flow Storage System (TEFSS)

    SciTech Connect

    None

    2010-09-09

    GRIDS Project: UTRC is developing a flow battery with a unique design that provides significantly more power than today's flow battery systems. A flow battery is a cross between a traditional battery and a fuel cell. Flow batteries store their energy in external tanks instead of inside the cell itself. Flow batteries have traditionally been expensive because the battery cell stack, where the chemical reaction takes place, is costly. In this project, UTRC is developing a new stack design that achieves 10 times higher power than today’s flow batteries. This high power output means the size of the cell stack can be smaller, reducing the amount of expensive materials that are needed. UTRC’s flow battery will reduce the cost of storing electricity for the electric grid, making widespread use feasible.

  17. Electrochemically Tunable Cell Adsorption on a Transparent and Adhesion-Switchable Superhydrophobic Polythiophene Film.

    PubMed

    Xu, Lianyi; Chen, Shuangshuang; Lu, Xuemin; Lu, Qinghua

    2015-06-01

    A superhydrophobic polythiophene film (SSPTH) is prepared by double-layer electrodeposition on an indium tin oxide (ITO) glass electrode. This film shows not only electroresponsive superhydrophobic features, but also high transparency compared with the usual polythiophene film. The water-droplet adhesion on the SSPTH film can be switched between sliding and pinned states under the applied potential. More intresetingly, the change in water-droplet adhesion results in a change in cell adsorption on the SSPTH film. The low-adhesion (dedoped) SSPTH films can prevent Hela cell adhesion, whereas high-adhesion (doped) SSPTH films can promote Hela cell adsorption. This controllable cell adhesion on a SSPTH film may be developed as a smart biointerface material. PMID:25864575

  18. High-rate electrochemical partial oxidation of methane in solid oxide fuel cells

    Microsoft Academic Search

    Zhongliang Zhan; Yuanbo Lin; Manoj Pillai; Ilwon Kim; Scott A. Barnett

    2006-01-01

    This paper describes results on direct-methane solid oxide fuel cell (air, LSM-YSZ|YSZ|Ni-YSZ, CH4) operation for combined electricity and syngas production. Thermodynamic equilibrium predictions showed that efficient methane conversion to syngas is expected for SOFC operating temperature >700°C and O2?\\/CH4 ratios of ?1. A simple thermal analysis was used to determine conditions where the cell produces enough heat to self-sustain its

  19. Electrochemical Properties of Low-Temperature Solid Oxide Fuel Cells Under Chromium Poisoning Conditions

    Microsoft Academic Search

    K. Min; C. W. Sun; W. Qu; X. G. Zhang; S. Yick; M. Robertson; C. Decès-Petit; R. Hui

    2009-01-01

    Rapid performance degradations of solid oxide fuel cells were observed when the chromium-forming metallic alloys were used as interconnects. The formation of strontium chromium oxide (SrCrO4) on the surface of Sr-doped perovskite cathode was believed to be one of the main causes for the cell degradation. This chromium-poisoning effect was not mitigated when the operating temperature was lowered to 600°C.

  20. Electrochemical properties of aryladamantanes as new overcharge protection compounds for lithium cells

    Microsoft Academic Search

    Yuu Watanabe; Hideyuki Morimoto; Shin-ichi Tobishima

    2006-01-01

    The development of new overcharge protection compounds for 4V-class lithium cells with LiCoO2 cathodes was attempted in order to protect the cells from the hazards of ignition and\\/or explosion when overcharged. At least two requirements must be met as regards overcharge protection compounds. They must have an oxidation potential (Eox) in the 4.6–4.8V range versus Li\\/Li+ and they must not

  1. In situ photoluminescence spectroscopy study of dynamic doping in sandwich-type light-emitting electrochemical cells

    NASA Astrophysics Data System (ADS)

    Meier, Sebastian B.; Hartmann, David; Sarfert, Wiebke; Tordera, Daniel; Bolink, Henk J.; Winnacker, Albrecht

    2012-09-01

    Photoluminescence (PL) spectroscopy has been performed in-situ on iridium(III) ionic transition metal complex (iTMC)- based sandwich-type light-emitting electrochemical cells (LECs) during device operation and after switch-off. It is demonstrated that driving the device leads to a considerable decrease of the PL intensity of the active layer. Two different time regimes for this decrease have been identified. The first one is characterized by a complete recovery of the PL after the device is turned off corroborating the existence of dynamically formed doped regions also in iTMC-based LECs. In the second regime the PL does not completely recover which is attributed to a permanent degradation of the active layer that is the main source for the low lifetime of the devices. Additionally, it is demonstrated how to externally stabilize the dynamic configuration leading to a half lifetime in excess of 1000 hours at simultaneous high brightness of more than 1000 cd/m2 and fast turn-on of less than one second.

  2. Electrochemical enhancement of nitric oxide removal from simulated lean-burn engine exhaust via solid oxide fuel cells.

    PubMed

    Huang, Ta-Jen; Wu, Chung-Ying; Lin, Yu-Hsien

    2011-07-01

    A solid oxide fuel cell (SOFC) unit is constructed with Ni-YSZ as the anode, YSZ as the electrolyte, and La(0.6)Sr(0.4)CoO(3)-Ce(0.9)Gd(0.1)O(1.95) as the cathode. The SOFC operation is performed at 600 °C with a cathode gas simulating the lean-burn engine exhaust and at various fixed voltage, at open-circuit voltage, and with an inert gas flowing over the anode side, respectively. Electrochemical enhancement of NO decomposition occurs when an operating voltage is generated; higher O(2) concentration leads to higher enhancement. Smaller NO concentration results in larger NO conversion. Higher operating voltage and higher O(2) concentration can lead to both higher NO conversion and lower fuel consumption. The molar rate of the consumption of the anode fuel can be very much smaller than that of NO to N(2) conversion. This makes the anode fuel consumed in the SOFC-DeNO(x) process to be much less than the equivalent amount of ammonia consumed in the urea-based selective catalytic reduction process. Additionally, the NO conversion increases with the addition of propylene and SO(2) into the cathode gas. These are beneficial for the application of the SOFC-DeNO(x) technology on treating diesel and other lean-burn engine exhausts. PMID:21667969

  3. Development of Polyaniline Using Electrochemical Technique for Plugging Pinholes in Cadmium Sulfide/Cadmium Telluride Solar Cells

    NASA Astrophysics Data System (ADS)

    Abdul-Manaf, N. A.; Echendu, O. K.; Fauzi, F.; Bowen, L.; Dharmadasa, I. M.

    2014-11-01

    Polyaniline (PAni) thin films were prepared by using an electrochemical polymerization technique on glass/FTO substrates by varying the deposition potential, deposition time, pH concentrations and heat treatment conditions. The structural, morphological, optical and electrical properties of electrodeposited PAni films were characterized using x-ray diffraction, scanning electron microscopy, UV-VIS spectroscopy, optical profilometry and D.C. conductivity measurements. Structural analysis shows the formation of the highest crystallinity for PAni thin film grown at V g 1654 mV. Optical absorption measurements have demonstrated a wide variety of energy band gaps ( E g), varying from ˜0.50 eV to 2.40 eV for PAni grown by tuning the pH value during the deposition. The electrical resistivity showed an increase from 0.37 × 106 ? cm to 3.91 × 106 ? cm when the pH increased from 2.00 to 6.50. The diode structures of glass/FTO/CdS/CdTe/PAni/Au were fabricated incorporating PAni as a pinhole plugging layer, and assessed for their photovoltaic activities. The results showed the enhancement of all device parameters, especially of open circuit voltage and fill factors. This improvement offers a great potential for enhancing solar cell performance and the device lifetime, and the latest results are presented in this paper.

  4. Development of ZnTe layers using an electrochemical technique for applications in thin-film solar cells

    NASA Astrophysics Data System (ADS)

    Fauzi, F.; Diso, D. G.; Echendu, O. K.; Patel, V.; Purandare, Y.; Burton, R.; Dharmadasa, I. M.

    2013-04-01

    Zinc telluride layers were grown by an electrochemical technique using acidic and aqueous solutions containing ZnCl2 and TeO2. The layers were deposited on glass/fluorine-doped tin oxide substrates using a two-electrode system. The deposited ZnTe layers were characterized using x-ray diffraction, x-ray fluorescence, Raman spectroscopy, optical absorption, photoelectrochemical cell measurements, scanning electron microscopy and 3D-atomic force microscopy (3D-AFM) for the structural, optical, electrical and morphological properties. The electrodeposited ZnTe layers grow as columns, and have cubic crystal structure, the band gap in the range of (2.00-2.20) eV and p-type electrical conductivity. Surface morphology studies using SEM indicate the presence of two types of material clusters varying in size up to ˜125 nm. 3D-AFM studies with higher magnification show that the material tends to grow as columns with different sizes leaving gaps in between in some areas.

  5. An electrochemical impedance spectroscopy study of polymer electrolyte membrane fuel cells electrocatalyst single wall carbon nanohorns-supported.

    PubMed

    Brandão, Lúcia; Boaventura, Marta; Passeira, Carolina; Gattia, Daniele Mirabile; Marazzi, Renzo; Antisari, Marco Vittori; Mendes, Adélio

    2011-10-01

    Electrochemical impedance spectroscopy (EIS) was used to study the polymer electrolyte membrane fuel cells (PEMFC) performance when using single wall carbon nanohorns (SWNH) to support Pt nanoparticles. Additionally, as-prepared and oxidized SWNH Pt-supports were compared with conventional carbon black. Two different oxidizing treatments were considered: oxygen flow at 500 degrees C and reflux in an acid solution at 85 degrees C. Both oxidizing treatments increased SWNH surface area; oxygen treatment increased surface area 4 times while acid treatment increased 2.6 times. The increase in surface area should be related to the opening access to the inner tube of SWNH. Acid treatment of SWNH increased chemical fragility and decreased electrocatalyst load in comparison with as-prepared SWNH. On the other hand, the oxygen treated SWNH sample allowed to obtain the highest electrocatalyst load. The use of as-prepared and oxygen treated SWNH showed in both cases catalytic activities 60% higher than using conventional carbon black as electrocatalyst support in PEMFC. Moreover, EIS analysis indicated that the major improvement in performance is related to the cathode kinetics in the as-prepared SWNH sample, while concerning the oxidized SWNH sample, the improvements are related to the electrokinetics in both anode and cathode electrodes. These improvements should be related with differences in the hydrophobic character between SWNH and carbon black. PMID:22400295

  6. Effect of secondary hyperparathyroidism serum on endothelial cells and intervention with Klotho.

    PubMed

    Chen, Cheng; Mao, Huijuan; Yu, Xiangbo; Sun, Bin; Zeng, Ming; Zhao, Xiufen; Qian, Jun; Liu, Jia; Xing, Changying

    2015-08-01

    The aim of the present study was to investigate the effect of the serum of patients with secondary hyperparathyroidism (SHPT) on endothelial cells and to examine the protective effect and the possible mechanism of Klotho. A total of three types of mixed serum from 15 patients with SHPT scheduled for parathyroidectomy, 10 chronic kidney disease (CKD) patients at stage 5 without SHPT and 15 healthy volunteers were collected. Initially, human umbilical vein endothelial cells (HUVECs) were incubated in vitro with the three types of serum and levels of proliferation were compared by assessing viable cell numbers with cell counting kit?8 (CCK?8). Subsequently, HUVECs were divided into three groups: Control group (healthy serum medium), SHPT group (SHPT serum) and Klotho treatment group (SHPT serum and Klotho). The proliferative and apoptotic levels of endothelial cells were evaluated by CCK?8 and flow cytometry, respectively. The levels of extracellular signal?regulated kinase (ERK1/2) and phosphorylated forms of ERK1/2 (p?ERK1/2) were detected using western blotting (with or without ERK1/2 inhibitor PD98059). The synthesis of nitric oxide (NO) was measured using the nitrate reduction method. The proliferation of HUVECs was inhibited by the serum from SHPT patients and CKD?5 patients without SHPT and the inhibitory effects of the SHPT serum were the most marked (P<0.05). Inhibition of HUVEC proliferation by SHPT serum occurred in a concentration?dependent manner within a specific range (5?20%; P<0.05) and also in a time?dependent manner within 6?24 h. Proliferation was partly restored and apoptosis was inhibited when 50?100 ng/ml Klotho was added into 10% SHPT serum (P<0.05). At the same time, the expression of p?ERK1/2 was upregulated, which may be inhibited by PD98059. The synthesis of NO was decreased in the SHPT group (P<0.05) and increased following treatment with Klotho (P<0.05). The results of the present study indicated that the proliferation of HUVECs was inhibited by the serum from SHPT patients. Klotho may partly antagonize this effect due to its inhibition of HUVEC apoptosis and upregulation of p?ERK1/2. PMID:25873020

  7. Mechanical and electrochemical performance of composite cathode contact materials for solid oxide fuel cells

    SciTech Connect

    Tucker, Michael C. [Lawrence Berkeley National Laboratory (LBNL); Dejonghe, Lutgard C. [Lawrence Berkeley National Laboratory (LBNL); Garcia-Negron, Valerie [Material Science and Technology Division, Oak Ridge National Laboratory; Trejo, Rosa M [ORNL; Lara-Curzio, Edgar [ORNL

    2013-01-01

    The feasibility of adding glass or inorganic binder to conventional SOFC cathode contact materials (CCM) in order to improve bonding to adjacent materials in the cell stack is assessed. Two glasses (SEM-COM SCZ-8 and Schott GM31107) and one inorganic binder (Aremco 644A) are mixed with LSM particles to produce composite CCM pastes. These are used to bond Mn1.5Co1.5O4-coated stainless steel mesh current collectors to anode-supported button cells. The cells are operated at 800 C for about 1000 h. The cell with SCZ-8 addition to the CCM displays quite stable operation (3.9%/1000 h degradation), whereas the other additives lead to somewhat higher degradation rate. Bonding of the CCM to coated stainless steel coupons is also assessed. Interfacial fracture toughness is determined using a four-point bend test. The fracture toughness for LSM Schott glass (12.3 N mm 1), LSM SCZ-8 glass (6.8 N mm 1) and LSM 644A binder (5.4 N mm 1) are significantly improved relative to pure LSM (1.7 N mm 1). Indeed, addition of binder or glass is found to improve bonding of the CCM layer without sacrificing cell performance.

  8. Electrochemical detection of intracellular and cell membrane redox systems in Saccharomyces cerevisiae

    PubMed Central

    Rawson, Frankie J.; Downard, Alison J.; Baronian, Keith H.

    2014-01-01

    Redox mediators can interact with eukaryote cells at a number of different cell locations. While cell membrane redox centres are easily accessible, the redox centres of catabolism are situated within the cytoplasm and mitochondria and can be difficult to access. We have systematically investigated the interaction of thirteen commonly used lipophilic and hydrophilic mediators with the yeast Saccharomyces cerevisiae. A double mediator system is used in which ferricyanide is the final electron acceptor (the reporter mediator). After incubation of cells with mediators, steady state voltammetry of the ferri/ferrocyanide redox couple allows quantitation of the amount of mediator reduced by the cells. The plateau current at 425?mV vs Ag/AgCl gives the analytical signal. The results show that five of the mediators interact with at least three different trans Plasma Membrane Electron Transport systems (tPMETs), and that four mediators cross the plasma membrane to interact with cytoplasmic and mitochondrial redox molecules. Four of the mediators inhibit electron transfer from S. cerevisiae. Catabolic inhibitors were used to locate the cellular source of electrons for three of the mediators. PMID:24910017

  9. Effective Transport Properties Accounting for Electrochemical Reactions of Proton-Exchange Membrane Fuel Cell Catalyst Layers

    SciTech Connect

    Pharoah, Jon; Choi, Hae-Won; Chueh, Chih-Che; Harvey, David

    2011-07-01

    There has been a rapidly growing interest in three-dimensional micro-structural reconstruction of fuel cell electrodes so as to derive more accurate descriptors of the pertinent geometric and effective transport properties. Due to the limited accessibility of experiments based reconstruction techniques, such as dual-beam focused ion beam-scanning electro microscopy or micro X-Ray computed tomography, within sample micro-structures of the catalyst layers in polymer electrolyte membrane fuel cells (PEMFCs), a particle based numerical model is used in this study to reconstruct sample microstructure of the catalyst layers in PEMFCs. Then the reconstructed sample structure is converted into the computational grid using body-fitted/cut-cell based unstructured meshing technique. Finally, finite volume methods (FVM) are applied to calculate effective properties on computational sample domains.

  10. Direct in situ probe of electrochemical processes in operating fuel cells.

    PubMed

    Nonnenmann, Stephen S; Kungas, Rainer; Vohs, John; Bonnell, Dawn A

    2013-07-23

    The function of systems and devices in many technologically important applications depends on dynamic processes in complex environments not accessible by structure and property characterization tools. Fuel cells represent an example in which interactions occur under extreme conditions: high pressure, high temperature, in reactive gas environments. Here, scanning surface potential microscopy is used to quantify local potential at electrode/electrolyte interfaces in operating solid oxide fuel cells at 600 °C. Two types of fuel cells are compared to demonstrate two mechanisms of ionic transport at interfaces. Lanthanum strontium ferrite-yttria-stabilized zirconia (LSF-YSZ) and lanthanum strontium manganite-yttria-stabilized zirconia (LSM-YSZ) cross-sectional electrode assemblies were measured to compare mixed ionic electronic conducting and electronic conducting mechanisms. Direct observation of the active zones in these devices yields characteristic length scales and estimates of activation barrier changes. PMID:23782103

  11. Recovery of renal function succeeding stem cell transplant: a case of C3 Glomerulonephiritis secondary to monoclonal gammopathy

    PubMed Central

    Andersen, Camilla Aakjær; Marcussen, Niels; Gregersen, Jon Waarst

    2013-01-01

    Membranoproliferative glomerulonephritis (MPGN) and C3 glomerulonephritis (C3 GN) can be secondary to monoclonal gammopathy and multiple myeloma. MPGN Type 1 is caused by activation of the classical pathway by immune complex formation, and C3 GN results from abnormalities in the alternative pathway of complement. In previously reported cases of MPGN and C3 GN secondary to monoclonal gammopathy/multiple myeloma, renal outcome has been poor. Here, we present the first patient, to our knowledge, who showed full renal recovery and normalization of the complement system after chemotherapy and stem cell transplantation.

  12. An in situ electrochemical cell for Q- and W-band EPR spectroscopy

    NASA Astrophysics Data System (ADS)

    Murray, Paul R.; Collison, David; Daff, Simon; Austin, Nicola; Edge, Ruth; Flynn, Brian W.; Jack, Lorna; Leroux, Fanny; McInnes, Eric J. L.; Murray, Alan F.; Sells, Daniel; Stevenson, Tom; Wolowska, Joanna; Yellowlees, Lesley J.

    2011-12-01

    A simple design for an in situ, three-electrode spectroelectrochemical cell is reported that can be used in commercial Q- and W-band (ca. 34 and 94 GHz, respectively) electron paramagnetic resonance (EPR) spectrometers, using standard sample tubing (1.0 and 0.5 mm inner diameter, respectively) and within variable temperature cryostat systems. The use of the cell is demonstrated by the in situ generation of organic free radicals (quinones and diimines) in fluid and frozen media, transition metal ion radical anions, and on the enzyme nitric oxide synthase reductase domain (NOSrd), in which a pair of flavin radicals are generated.

  13. Capped mRNAs with Reduced Secondary Structure Can Function in Extracts from Poliovirus-Infected Cells

    PubMed Central

    Sonenberg, Nahum; Guertin, Denise; Lee, Kevin A. W.

    1982-01-01

    Extracts from poliovirus-infected HeLa cells were used to study ribosome binding of native and denatured reovirus mRNAs and translation of capped mRNAs with different degrees of secondary structure. Here, we demonstrate that ribosomes in extracts from poliovirus-infected cells could form initiation complexes with denatured reovirus mRNA, in contrast to their inability to bind native reovirus mRNA. Furthermore, the capped alfalfa mosaic virus 4 RNA, which is most probably devoid of stable secondary structure at its 5? end, could be translated at much higher efficiency than could other capped mRNAs in extracts from poliovirus-infected cells. Images PMID:14582204

  14. ESM of Ionic and Electrochemical Phenomena on the Nanoscale

    SciTech Connect

    Kalinin, Sergei V. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Kumar, Amit [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Balke, Nina [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); McCorkle, Morgan [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Guo, Senli [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Arruda, Thomas M. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Jesse, Stephen [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

    2011-11-01

    Operation of energy storage and conversion devices is ultimately controlled by series of intertwined ionic and electronic transport processes and electrochemical reactions at surfaces and interfaces, strongly mediated by strain and mechanical processes. In a typical fuel cell, these include chemical species transport in porous cathode and anode materials, gas-solid electrochemical reactions at grains and triple-phase boundaries (TPBs), ionic and electronic flows in multicomponent electrodes, and chemical and electronic potential drops at internal interfaces in electrodes and electrolytes. All these phenomena are sensitively affected by the microstructure of materials from device level to the atomic scales. Similar spectrum of length scales and phenomena underpin operation of other energy systems including primary and secondary batteries, as well as hybrid systems such flow and metal-air/water batteries.

  15. Electrochemical Imaging of Dopamine Release from Three-Dimensional-Cultured PC12 Cells Using Large-Scale Integration-Based Amperometric Sensors.

    PubMed

    Abe, Hiroya; Ino, Kosuke; Li, Chen-Zhong; Kanno, Yusuke; Inoue, Kumi Y; Suda, Atsushi; Kunikata, Ryota; Matsudaira, Masahki; Takahashi, Yasufumi; Shiku, Hitoshi; Matsue, Tomokazu

    2015-06-16

    In the present study, we used a large-scale integration (LSI)-based amperometric sensor array system, designated Bio-LSI, to image dopamine release from three-dimensional (3D)-cultured PC12 cells (PC12 spheroids). The Bio-LSI device consists of 400 sensor electrodes with a pitch of 250 ?m for rapid electrochemical imaging of large areas. PC12 spheroids were stimulated with K(+) to release dopamine. Poststimulation dopamine release from the PC12 spheroids was electrochemically imaged using the Bio-LSI device. Bio-LSI clearly showed the effects of the dopaminergic drugs l-3,4-dihydroxyphenylalanine (l-DOPA) and reserpine on K(+)-stimulated dopamine release from PC12 spheroids. Our results demonstrate that dopamine release from PC12 spheroids can be monitored using the device, suggesting that the Bio-LSI is a promising tool for use in evaluating 3D-cultured dopaminergic cells and the effects of dopaminergic drugs. To the best of our knowledge, this report is the first to describe electrochemical imaging of dopamine release by PC12 spheroids using LSI-based amperometric sensors. PMID:25971414

  16. Fuel cells are used to produce electric-ity electrochemically from many differ-

    E-print Network

    electrons from inside the cell to the electrode. The finding that bacteria capable of dissimila- tory iron. The yeast Pichia anomala has redox enzymes on its outer membrane and can produce current in an MFC5 dissimilatory metal- reducing bacteria use iron oxides initially revealed two m

  17. A two-population bio-electrochemical model of a microbial fuel cell

    Microsoft Academic Search

    R. P. Pinto; B. Srinivasan; M.-F. Manuel; B. Tartakovsky

    2010-01-01

    This work presents a two-population model describing the competition of anodophilic and methanogenic microbial populations for a common substrate in a microbial fuel cell (MFC). Fast numerical solution of the model is provided by using ordinary differential equations to describe biomass growth and retention in the anodic compartment. The model parameters are estimated and validated using experimental results obtained in

  18. Performance of the direct formic acid fuel cell with electrochemically modified palladium–antimony anode catalyst

    Microsoft Academic Search

    John L. Haan; Kristin M. Stafford; Robert D. Morgan; Richard I. Masel

    2010-01-01

    Previous work has shown that palladium catalysts are quite active for formic acid electrooxidation, but the catalysts need to be periodically regenerated to remove a CO impurity from the surface. The objective of this paper is to determine whether antimony additions could suppress the CO formation under fuel cell conditions. We find that antimony doubles the rate of reaction in

  19. JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 15, NO. 5, OCTOBER 2006 1243 A MEMS Photosynthetic Electrochemical Cell

    E-print Network

    Lin, Liwei

    -scale polymer electrolyte fuel cell was adapted to construct a MEMS micro-biofluidic device--with anodeJOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL. 15, NO. 5, OCTOBER 2006 1243 A MEMS Photosynthetic Lin, Member, IEEE, ASME, Fellow Abstract--A microelectromechanical systems (MEMS) photo- synthetic

  20. Positive Energy From rechargeable batteries to fuel cells: electrochemical energy as one

    E-print Network

    Andelman, David

    of the fascinating and green alternatives to combustion engines Yaakov Vilenchik1 , David Andelman2 and Emanuel such as rechargeable batteries and fuel cells, which in the future could replace the combustion engine. We equally with oxygen in the air), which in turn is used to heat water into steam. Steam under high pressure has large

  1. Secondary Involvement of the Mandible due to Basal Cell Carcinoma: A Case Report

    PubMed Central

    Mosannen Mozaffary, Pegah; Delavarian, Zahra; Amirchaghmaghi, Maryam; Dalirsani, Zohreh; Vazifeh Mostaan, Leila; Saghafi Khadem, Shadi; Ghalavani, Hanieh

    2015-01-01

    Basal cell carcinoma (BCC) is the most common cutaneous malignancy among Caucasians. Rare examples of aggressive and neglected BCC have been reported. Here we report a unique case of a neglected BCC with significant jaw involvement. A 50-year-old female, referred by an otorhinologist, presented with a large ulcer on her chin, which was extended to her mandibular vestibule. The ulcer was 9×5.5 cm in size, and tissue destruction, necrosis was observed in the central portion, and the mandibular bone was exposed. On intraoral examination, tooth mobility and severe bone loss were evident. Due to the primary cutaneous origin of the lesion, BCC was considered as preliminary diagnosis. Biopsy was performed and diagnosis of BCC was confirmed. The diseased mandibular bone was resected and reconstructed with a surgical plate. The soft tissue defect was reconstructed with deltopectoral flap. The patient refused secondary stage plastic surgery. Although BCC is not a lethal malignancy, if left untreated and neglected, it can result in severe destruction, disfigurement, and even mortality. PMID:25999630

  2. Selective and quantitative nitrate electroreduction to ammonium using a porous copper electrode in an electrochemical flow cell

    E-print Network

    Paris-Sud XI, Université de

    1 Selective and quantitative nitrate electroreduction to ammonium using a porous copper electrode nitrate solutions to ammonium and which can be subsequently implemented on a large scale application electrochemical process to achieve a selective and quantitative transformation of concentrated nitrate

  3. Identification of Volatile Biomarkers of Gastric Cancer Cells and Ultrasensitive Electrochemical Detection based on Sensing Interface of Au-Ag Alloy coated MWCNTs

    PubMed Central

    Zhang, Yixia; Gao, Guo; Liu, Huijuan; Fu, Hualin; Fan, Jun; Wang, Kan; Chen, Yunsheng; Li, Baojie; Zhang, Chunlei; Zhi, Xiao; He, Lin; Cui, Daxiang

    2014-01-01

    Successful development of novel electrochemical biosensing interface for ultrasensitive detection of volatile biomarkers of gastric cancer cells is a challenging task. Herein we reported to screen out novel volatile biomarkers associated with gastric cancer cells and develop a novel Au-Ag alloy composites-coated MWCNTs as sensing interface for ultrasensitive detection of volatile biomarkers. MGC-803 gastric cancer cells and GES-1 gastric mucous cells were cultured in serum-free media. The sample preparation approaches and HS-SPME conditions were optimized for screening volatile biomarkers. Volatiles emitted from the headspace of the cells/medium culture were identified using GC-MS. The Au-Ag nanoparticles-coated multiwalled carbon nanotubes were prepared as a sensing interface for detection of volatile biomarkers. Results showed that eight different volatile metabolites were screened out between MGC-803 cells and GES-1 cells. Two compounds such as 3-octanone and butanone were specifically present in the headspace of the MGC-803 cells. Three volatiles such as 4-isopropoxybutanol, nonanol and 4-butoxy 1-butanol coexisted in the headspace of both the MGC-803 cells and the GES-1 cells, their concentrations in the headspace of the GES-1cells were markedly higher than those in the MGC-803 cells, three volatiles such as formic acid propyl ester, 1.4-butanediol and 2, 6, 11-trimethyl dodecane solely existed in the headspace of the GES-1 cells. The nanocomposites of MWNTs loaded with Au-Ag nanoparticles were prepared as a electrochemical sensing interface for detection of two volatile biomarkers, cyclic voltammetry studies showed that the fabricated sensor could detect 3-octanone in the range of 0~0.0025% (v/v) and with a detection limitation of 0.3 ppb, could detect butanone in the range of 0 ~ 0.055% (v/v), and with a detection limitation of 0.5 ppb, and exhibited good selectivity. The novel electrochemical biosensor combined with volatile biomarkers of gastric cancer owns great potential in applications such as early diagnosis and the prognosis of gastric cancer in near future. PMID:24465273

  4. Identification of novel transcription factors regulating secondary cell wall formation in Arabidopsis

    PubMed Central

    Cassan-Wang, Hua; Goué, Nadia; Saidi, Mohammed N.; Legay, Sylvain; Sivadon, Pierre; Goffner, Deborah; Grima-Pettenati, Jacqueline

    2013-01-01

    The presence of lignin in secondary cell walls (SCW) is a major factor preventing hydrolytic enzymes from gaining access to cellulose, thereby limiting the saccharification potential of plant biomass. To understand how lignification is regulated is a prerequisite for selecting plant biomass better adapted to bioethanol production. Because transcriptional regulation is a major mechanism controlling the expression of genes involved in lignin biosynthesis, our aim was to identify novel transcription factors (TFs) dictating lignin profiles in the model plant Arabidopsis. To this end, we have developed a post-genomic approach by combining four independent in-house SCW-related transcriptome datasets obtained from (1) the fiber cell wall-deficient wat1 Arabidopsis mutant, (2) Arabidopsis lines over-expressing either the master regulatory activator EgMYB2 or (3) the repressor EgMYB1 and finally (4) Arabidopsis orthologs of Eucalyptus xylem-expressed genes. This allowed us to identify 502 up- or down-regulated TFs. We preferentially selected those present in more than one dataset and further analyzed their in silico expression patterns as an additional selection criteria. This selection process led to 80 candidates. Notably, 16 of them were already proven to regulate SCW formation, thereby validating the overall strategy. Then, we phenotyped 43 corresponding mutant lines focusing on histological observations of xylem and interfascicular fibers. This phenotypic screen revealed six mutant lines exhibiting altered lignification patterns. Two of them [Bel-like HomeoBox6 (blh6) and a zinc finger TF] presented hypolignified SCW. Three others (myb52, myb-like TF, hb5) showed hyperlignified SCW whereas the last one (hb15) showed ectopic lignification. In addition, our meta-analyses highlighted a reservoir of new potential regulators adding to the gene network regulating SCW but also opening new avenues to ultimately improve SCW composition for biofuel production. PMID:23781226

  5. Secondary Products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In spite of their name, "secondary" products are essential for plant survival. They are required for basic cell functions as well as communicating the plant's presence to the surrounding environment and defense against pests as defined in the broad sense (i.e., diseases, nematodes, insects and plan...

  6. Influence of counter-anions during electrochemical deposition of ZnO on the charge transport dynamics in dye-sensitized solar cells.

    PubMed

    Richter, Christoph; Beu, Max; Schlettwein, Derck

    2015-01-21

    Porous ZnO/EosinY films have been electrochemically deposited by oxygen reduction in the presence of a zinc salt from EosinY-containing aqueous solutions, with either chloride or perchlorate as the counter anion. EosinY was removed and the films were sensitised by D149. These electrodes were used for dye-sensitised solar cells (DSCs), and charge transport in the porous network was studied by intensity modulated current/voltage spectroscopy (IMVS/IMPS) and electrochemical impedance spectroscopy (EIS) under illumination. Doping of ZnO during the electrodeposition could be proven by changes in the charge transport in ZnO and could be shown to occur when chloride was used as the counter ion. By using perchlorate as the counter ion, on the other hand, a more reproducible occupation of trap levels was obtained at, however, slightly lower voltages in DSCs whose origin is discussed in detail. PMID:25474267

  7. New Method for Super Hydrophobic Treatment of Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells Using Electrochemical Reduction of Diazonium Salts.

    PubMed

    Thomas, Yohann R J; Benayad, Anass; Schroder, Maxime; Morin, Arnaud; Pauchet, Joël

    2015-07-15

    The purpose of this article is to report a new method for the surface functionalization of commercially available gas diffusion layers (GDLs) by the electrochemical reduction of diazonium salt containing hydrophobic functional groups. The method results in superhydrophobic GDLs, over a large area, without pore blocking. An X-ray photoelectron spectroscopy study based on core level spectra and chemical mapping has demonstrated the successful grafting route, resulting in a homogeneous distribution of the covalently bonded hydrophobic molecules on the surface of the GDL fibers. The result was corroborated by contact angle measurement, showing similar hydrophobicity between the grafted and PTFE-modified GDLs. The electrochemically modified GDLs were tested in proton exchange membrane fuel cells under automotive, wet, and dry conditions and demonstrated improved performance over traditional GDLs. PMID:26098140

  8. The electrochemical fluorination of polymeric materials for high energy density aqueous and non-aqueous battery and fuel cell separators

    NASA Technical Reports Server (NTRS)

    Liu, C. C.

    1983-01-01

    A computerized system was established and the electrochemical fluorination of trichloroethylene, polyacrylic acid and polyvinyl alcohol in anhydrous hydrogen fluoride was attempted. Both solid substrates as well as membranes were used. Some difficulties were found in handling and analyzing the solid substrates and membranes. Further studies are needed in this area. A microprocessor aided electrochemical fluorination system capable of obtaining highly reproducible experimental results was established.

  9. Electrochemical detection in a microfluidic device of oxidative stress generated by macrophage cells.

    PubMed

    Amatore, Christian; Arbault, Stéphane; Chen, Yong; Crozatier, Cécile; Tapsoba, Issa

    2007-02-01

    The release of reactive oxygen species (ROS) or reactive nitrogen species (RNS), i.e., the initial phase of oxidative stress, by macrophage cells has been studied by electrochemistry within a microfluidic device. Macrophages were first cultured into a detection chamber containing the three electrodes system and were subsequently stimulated by the microinjection of a calcium ionophore (A23187). Their production of ROS and RNS was then measured by amperometry at the surface of a platinized microelectrode. The fabricated microfluidic device provides an accurate measurement of oxidative release kinetics with an excellent reproducibility. We believe that such a method is simple and versatile for a number of advanced applications based on the detection of biological processes of secretion by a few or even a single living cell. PMID:17268626

  10. Enhanced electrochemical performance in the development of the aluminum\\/hydrogen peroxide semi-fuel cell

    Microsoft Academic Search

    E. G. Dow; R. R. Bessette; G. L. Seeback; C. Marsh-Orndorff; H. Meunier; J. VanZee; M. G. Medeiros

    1997-01-01

    Significant accomplishments from this research effort have defined and characterized the nature and rate of the chemical dynamics at the anode and cathode, thus allowing the development of the aluminum\\/hydrogen peroxide couple as an energy-dense semi-fuel cell system. This effort has included the investigation of new aluminum alloys, development of new electrocatalysts for the hydrogen peroxide, optimization of the operating

  11. Novel graphite\\/TiO 2 electrochemical cells as a safe electric energy storage system

    Microsoft Academic Search

    Arjun Kumar Thapa; Hiroyoshi Nakamura; Tatsumi Ishihara; Nariaki Moriyama; Toshihiko Kawamura; Hongyu Wang; Masaki Yoshio

    2010-01-01

    A graphite\\/TiO2 full cell has been developed as a new safety energy storage system using a highly safety process. The crystal structures of the anatase TiO2 electrode have been investigated with respect to the performance of the electrodes. Due to the large anion intercalation into the graphite positive electrode, the possible charging potential can be raised to around 5.3V against

  12. Screen-printed multicrystalline silicon solar cells with porous silicon antireflective layer formed by electrochemical etching

    Microsoft Academic Search

    Jae-Hong Kwon; Soo-Hong Lee; Byeong-Kwon Ju

    2007-01-01

    The latest results on the use of porous silicon (PS) as an antireflection coating (ARC) in simplified processing for multicrystalline silicon (mc-Si) solar cells are presented. A PS layer with optimal antireflection characteristics was obtained for charge density (Q) of 5.2 C\\/cm2. The weighted reflectance was reduced to 4.7% in the range of wavelengths between 400 and 1000 nm. Also,

  13. Allicin disrupts the cell's electrochemical potential and induces apoptosis in yeast

    Microsoft Academic Search

    Martin C. H. Gruhlke; Daniela Portz; Michael Stitz; Awais Anwar; Thomas Schneider; Claus Jacob; Nikolaus L. Schlaich; Alan J. Slusarenko

    2010-01-01

    The volatile substance allicin gives crushed garlic (Allium sativum) its characteristic odor and is a pro-oxidant that undergoes thiol–disulfide exchange reactions with –SH groups in proteins and glutathione. The antimicrobial activity of allicin is suspected to be due to the oxidative inactivation of essential thiol-containing enzymes. We investigated the hypothesis that at threshold inhibitory levels allicin can shunt yeast cells

  14. Simultaneous electrochemical removal of copper and chemical oxygen demand using a packed-bed electrode cell

    Microsoft Academic Search

    Katsuki Kusakabe; Hiroshi Nishida; Shigeharu Morooka; Yasuo Kato

    1986-01-01

    Copper ions and chelating agents in water were treated simultaneously by using a packed-bed electrode cell. The cathode packings were graphite particles or graphite felt; the anode packings were platinum-plated titanium pellets, ß-PbO2 particles or oxidized lead spheres. The catholyte contained ethylenediaminetetraacetic acid (EDTA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA) or glycine chelate of copper, while the anolyte contained the

  15. Thermal behavior and electrochemical heat generation in a commercial 40 Ah lithium ion pouch cell

    NASA Astrophysics Data System (ADS)

    Schuster, Elke; Ziebert, Carlos; Melcher, Andreas; Rohde, Magnus; Seifert, Hans Jürgen

    2015-07-01

    Quantitative data on the thermal behavior of lithium ion batteries under charging and discharging conditions are essential for designing thermal management systems and improving battery safety. In this work, commercial 40 Ah lithium ion pouch cells with Li(Ni1/3Mn1/3Co1/3)O2 cathodes were tested under isoperibolic and adiabatic conditions in an Accelerating Rate Calorimeter at different charging/discharging currents from 5 A to 40 A. Adiabatic tests simulate the worst-case scenario of a battery pack without cooling. For charging and discharging an overall exothermic behavior was found and a total temperature increase for one half cycle between 3 and 11 K. Isoperibolic tests simulate a single cell under constant environmental temperature. Here an exothermic behavior for discharging and an endothermic behavior for charging were observed. To transfer the measured temperature changes into heat data, the effective specific heat capacity and the heat transfer coefficient were determined. For the first time the heat generation data for a large format pouch cell have been determined using both isoperibolic and adiabatic conditions. These data were compared with the total heat data calculated as the sum of reversible and irreversible heat that were measured by potentiometric and current interruption techniques respectively. A good agreement was found between all three heat generation determination methods.

  16. Electrochemical studies of membranes, catalysts, and fuels for direct oxidation fuel cells

    NASA Astrophysics Data System (ADS)

    McGrath, Kimberly Michelle

    Over the past 15 years, the electrical performance of direct methanol fuel cells (DMFCs) has increased at least tenfold. While the DMFC has a theoretical energy density of 6094 W h/kg, only 1000-3200 W h/kg of this energy is realized in practice. Although most portable power applications only necessitate several W h/kg, performance and cost issues associated with polymer electrolyte membranes (PEMs), anode and cathode catalysts, system design, and operational considerations must be overcome for DMFCs to have a role in the methanol economy. Water management within a direct methanol fuel cell is critical to achieve optimal performance, especially at higher current densities where increased water production occurs. The semi-interpenetrating network composite membrane, poly(styrenesulfonic acid) poly(vinylidene fluoride) is shown to have dramatically decreased water flux due to electroosmotic drag compared to the conventional material, NafionRTM--117. In addition, a potentiometric method for screening new proton exchange membrane candidates is illustrated as a rapid method for determination of methanol crossover. Electrooxidation of other small hydrocarbon fuels, such as formic acid, methyl formate, ethylene glycol, and dimethyl oxalate were investigated in a direct oxidation fuel cell (DOFC). At room temperature, formic acid outperforms methanol by virtue of reduction in fuel crossover. Alternative catalyst systems for these fuels must be further investigated. Gold has a tolerance for methanol while promoting reduction of oxidation, and has proved to be a promising candidate as a cathode catalyst.

  17. SND2, a NAC transcription factor gene, regulates genes involved in secondary cell wall development in Arabidopsis fibres and increases fibre cell area in Eucalyptus

    PubMed Central

    2011-01-01

    Background NAC domain transcription factors initiate secondary cell wall biosynthesis in Arabidopsis fibres and vessels by activating numerous transcriptional regulators and biosynthetic genes. NAC family member SND2 is an indirect target of a principal regulator of fibre secondary cell wall formation, SND1. A previous study showed that overexpression of SND2 produced a fibre cell-specific increase in secondary cell wall thickness in Arabidopsis stems, and that the protein was able to transactivate the cellulose synthase8 (CesA8) promoter. However, the full repertoire of genes regulated by SND2 is unknown, and the effect of its overexpression on cell wall chemistry remains unexplored. Results We overexpressed SND2 in Arabidopsis and analyzed homozygous lines with regards to stem chemistry, biomass and fibre secondary cell wall thickness. A line showing upregulation of CesA8 was selected for transcriptome-wide gene expression profiling. We found evidence for upregulation of biosynthetic genes associated with cellulose, xylan, mannan and lignin polymerization in this line, in agreement with significant co-expression of these genes with native SND2 transcripts according to public microarray repositories. Only minor alterations in cell wall chemistry were detected. Transcription factor MYB103, in addition to SND1, was upregulated in SND2-overexpressing plants, and we detected upregulation of genes encoding components of a signal transduction machinery recently proposed to initiate secondary cell wall formation. Several homozygous T4 and hemizygous T1 transgenic lines with pronounced SND2 overexpression levels revealed a negative impact on fibre wall deposition, which may be indirectly attributable to excessive overexpression rather than co-suppression. Conversely, overexpression of SND2 in Eucalyptus stems led to increased fibre cross-sectional cell area. Conclusions This study supports a function for SND2 in the regulation of cellulose and hemicellulose biosynthetic genes in addition of those involved in lignin polymerization and signalling. SND2 seems to occupy a subordinate but central tier in the secondary cell wall transcriptional network. Our results reveal phenotypic differences in the effect of SND2 overexpression between woody and herbaceous stems and emphasize the importance of expression thresholds in transcription factor studies. PMID:22133261

  18. A two-population bio-electrochemical model of a microbial fuel cell.

    PubMed

    Pinto, R P; Srinivasan, B; Manuel, M-F; Tartakovsky, B

    2010-07-01

    This work presents a two-population model describing the competition of anodophilic and methanogenic microbial populations for a common substrate in a microbial fuel cell (MFC). Fast numerical solution of the model is provided by using ordinary differential equations to describe biomass growth and retention in the anodic compartment. The model parameters are estimated and validated using experimental results obtained in four continuous-flow air-cathode MFCs operated at various external resistances and organic loads. Model analysis demonstrates the influence of operating conditions on MFC performance and suggests ways to maximize MFC power output. The model is suitable both for process optimization and on-line control applications. PMID:20171879

  19. Improved electrochemical properties of surface-coated Li(Ni,Co,Mn)0{sub 2} cathode material for Li secondary batteries.

    SciTech Connect

    Kang, S.-H.; Amine, K.; Chemical Engineering

    2006-01-01

    The surface of Li(Ni{sub 0.4}Co{sub 0.2}Mn{sub 0.4})O{sub 2} was coated with amorphous aluminum oxide using Al-isopropoxide. The effect of the surface coating on the cycling performance and high-temperature storage characteristics was investigated using coin-type cells. The surface-coated materials showed superior capacity retention at 55C as well as at room temperature and limited impedance rise during high-temperature storage compared with the uncoated material. From the a.c. impedance measurement, it was found that the uncoated material exhibited very large increase in the cathode/electrolyte interfacial impedance during cycling whereas the surface-coated materials showed a limited increase in the interfacial impedance.

  20. Characteristics of lithium-ion-conducting composite polymer-glass secondary cell electrolytes

    NASA Astrophysics Data System (ADS)

    Zhang, Xiang-Wu; Wang, Chunsheng; Appleby, A. John; Little, Frank E.

    A family of lithium-ion-conducting composite polymer-glass electrolytes containing the glass composition 14Li 2O-9Al 2O 3-38TiO 2-39P 2O 5 (abbreviated as (LiAlTiP) xO y) with high ionic conductivity, an excellent electrochemical stability range, and high compatibility with lithium insertion anodes is described. An optimized composition has a room temperature conductivity of 1.7×10 -4 S cm -1, an Li + transference number of 0.39, and an electrochemical stability window to +5.1 V versus Li/Li +. It also has good interfacial stability under both open-circuit and lithium metal plating-stripping conditions and provides good shelf-life.