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1

Primary and secondary room temperature molten salt electrochemical cells  

NASA Astrophysics Data System (ADS)

Three novel primary cells which use room temperature molten salt electrolytes are examined and found to have high open circuit potentials in the 1.75-2.19 V range, by comparison with the Al/AlCl3-MEICl concentration cell; their cathodes were of FeCl3-MEICl, WCl6-MEICl, and Br2/reticulated vitreous carbon together with Pt. Also, secondary electrochemical cell candidates were examined which combined the reversible Al/AlCl3-MEICl electrode with reversible zinc and cadmium molten salt electrodes to yield open circuit potentials of about 0.7 and 1.0 V, respectively. Room temperature molten salts' half-cell reduction potentials are given.

Reynolds, G. F.; Dymek, C. J., Jr.

1985-07-01

2

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

DOEpatents

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.

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

1982-07-07

3

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

DOEpatents

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.

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

1981-05-22

4

Electrochemical cell  

DOEpatents

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.

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

1996-07-16

5

Electrochemical cell  

DOEpatents

An electrochemical cell 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.degree. 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.

Redey, Laszlo I. (6851 Carpenter St., Downers Grove, IL 60516); Vissers, Donald R. (611 Clover Ct., Naperville, IL 60540); Prakash, Jai (2205 Arbor Cir. 8, Downers Grove, IL 60515)

1996-01-01

6

Electrochemical cell  

DOEpatents

An electrochemical cell 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.degree. 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.

Redey, Laszlo I. (Downers Grove, IL); Vissers, Donald R. (Naperville, IL); Prakash, Jai (Downers Grove, IL)

1994-01-01

7

Electrochemical cell  

DOEpatents

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.

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

1994-02-01

8

Electrochemical cell  

DOEpatents

An electrochemical cell 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.

Redey, Laszlo I. (Downers Grove, IL); Vissers, Donald R. (Naperville, IL); Prakash, Jai (Downers Grove, IL)

1994-01-01

9

Electrochemical cell  

DOEpatents

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.

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

1992-01-01

10

Electrochemical cell  

DOEpatents

An electrochemical cell 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." 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." 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.

Redey, Laszlo I. (Downers Grove, IL); Myles, Kevin M. (Downers Grove, IL); Vissers, Donald R. (Naperville, IL); Prakash, Jai (Downers Grove, IL)

1996-01-01

11

Electrochemical cell  

DOEpatents

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.

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

1992-08-25

12

Electrochemical cell  

DOEpatents

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.

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

1994-08-23

13

Electrochemical cell  

SciTech Connect

A rechargeable electrochemical cell (10 in fig. 1) has a negative electrode (11) with an active surface (11') of copper; a positive electrode (12) with an active surface (12') of lead dioxide, spaced therefrom; in an aqueous acid electrolyte (13) of fluoboric, fluosilicic, sulfamic, or perchloric acid, in which both divalent copper and divalent lead ions are soluble during discharging, and from which smooth and adherent deposits may be obtained during charging; and a container (14) with an electrically nonconductive inner surface (14') that is chemically resistant to the electrolyte (13). A similar cell (30 in fig. 5) comprises also bipolar electrodes (32,31) similar in shape to the negative electrode (31) and the positive electrode (32), positioned between them and substantially parallel to them. As in fig. 2, the container may comprise a fluid-tight enclosure (24,25) with an optional pressure relief valve (28).

Schaer, G.R.

1980-05-20

14

Electrochemical cell method  

DOEpatents

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.

Kaun, T.D.; Eshman, P.F.

1980-05-09

15

Electrochemical behavior of Li/LiV3O8 secondary cells  

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

16

Electrochemical cell  

SciTech Connect

There is provided a novel primary cell which comprises in combination an anode made of lithium, of sodium or of a dischargeable alloy of same, which has a melting point above 80/sup 0/ C., an electrolyte comprising a solvent or solvent mixture which is suited to dissolve a polysulfide to attain a concentration of at least 0.01 M, and to dissolve an electrolyte salt to give a solution of at least 0.1 M, said solvent or solvent system having an own EMF against the anode which is low enough so as not to prevent the reaction of the anode material with said polysulfide to form a M/sub 2/S solid electrolyte interphase, said electrolyte containing a polysulfide M/sub 2/S /SUB n/ where M is selected from lithium and sodium, the concentration of the polysulfide being high enough and n being low enough to result in a predetermined low selfdischarge of the cell, and an inert porous current collector. The current collector may be charged with sulfur. The solvent system may contain a solvent which reduces the solubility of the polysulfide, thus increasing the conductivity of the electrolyte.

Peled, E.; Yamin, H.

1983-10-18

17

Electrochemical storage cell  

SciTech Connect

Electrochemical storage cell of the sodium and sulfur type with at least one anode space for receiving the anolyte and a cathode space for receiving the catholyte, which are separated from each other by an alkali ion-conducting solid electrolyte and are bounded at least in some areas by a metallic housing. The cathode space is in communication via at least one connecting element with at least one supply container for the sodium polysulfide being formed in the chemical reaction.

Haberfellner, F.; Prappacher, G.

1985-01-08

18

Miniaturized electrochemical flow cells.  

PubMed

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 microm 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-microm channels, while there is some iR drop in cells with 13-microm 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

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

2003-02-15

19

Electrochemical photovoltaic cells and electrodes  

DOEpatents

Improved electrochemical photovoltaic cells and electrodes for use therein, particularly electrodes employing amorphous silicon or polyacetylene coating are produced by a process which includes filling pinholes or porous openings in the coatings by electrochemical oxidation of selected monomers to deposit insulating polymer in the openings.

Skotheim, Terje A. (East Patchogue, NY)

1984-01-01

20

Electrochemical cell with high conductivity glass electrolyte  

DOEpatents

A secondary electrochemical cell with sodium-sulfur or other molten reactants is provided with a ionically conductive glass electrolyte. The cell is contained within an electrically conductive housing with a first portion at negative potential and a second portion insulated therefrom at positive electrode potential. The glass electrolyte is formed into a plurality of elongated tubes and placed lengthwise within the housing. The positive electrode material, for instance sulfur, is sealed into the glass electrolyte tubes and is provided with an elongated axial current collector. The glass electrolyte tubes are protected by shield tubes or sheets that also define narrow annuli for wicking of the molten negative electrode material.

Nelson, Paul A. (Wheaton, IL); Bloom, Ira D. (Lisle, IL); Roche, Michael F. (Glen Ellyn, IL)

1987-01-01

21

Electrochemical cell with high conductivity glass electrolyte  

DOEpatents

A secondary electrochemical cell with sodium-sulfur or other molten reactants is provided with a ionically conductive glass electrolyte. The cell is contained within an electrically conductive housing with a first portion at negative potential and a second portion insulated therefrom at positive electrode potential. The glass electrolyte is formed into a plurality of elongated tubes and placed lengthwise within the housing. The positive electrode material, for instance sulfur, is sealed into the glass electrolyte tubes and is provided with an elongated axial current collector. The glass electrolyte tubes are protected by shield tubes or sheets that also define narrow annuli for wicking of the molten negative electrode material. 6 figs.

Nelson, P.A.; Bloom, I.D.; Roche, M.F.

1987-04-21

22

Electrochemical cell with high conductivity glass electrolyte  

DOEpatents

A secondary electrochemical cell with sodium-sulfur or other molten reactants is provided with an ionically conductive glass electrolyte. The cell is contained within an electrically conductive housing with a first portion at negative potential and a second portion insulated therefrom at positive electrode potential. The glass electrolyte is formed into a plurality of elongated tubes and placed lengthwise within the housing. The positive electrode material, for instance sulfur, is sealed into the glass electrolyte tubes and is provided with an elongated axial current collector. The glass electrolyte tubes are protected by shield tubes or sheets that also define narrow annuli for wicking of the molten negative electrode material.

Nelson, P.A.; Bloom, I.D.; Roche, M.F.

1986-04-17

23

Separator material for electrochemical cells  

DOEpatents

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.

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

1991-03-26

24

Separator material for electrochemical cells  

SciTech Connect

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.

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

1991-01-01

25

Non-aqueous electrochemical cell  

SciTech Connect

This patent describes a non-aqueous electrochemical cell. It comprises: an anode, a cathode and a non-aqueous electrolyte, the anode comprising a substrate having a mixture of at lease two elements selected from the group consisting of sodium, potassium, cesium and rubidium, and the anode having a skin or coating of an alkali metal.

Cipriano, R.A.

1992-02-04

26

Electrochemical power sources: Primary and secondary batteries  

Microsoft Academic Search

The development of voltaic cells is reviewed, and the basic thermodynamic and kinetic principles underlying the conversion of chemical to electrical energy are outlined. The most popular types of primary batteries for civilian use are discussed including the neutral air-depolarized, Leclanche, and alkaline manganese batteries as well as the mercury\\/zinc and silver\\/zinc button cell assemblies. The two basic groups of

M. Barak

1980-01-01

27

Compacted carbon for electrochemical cells  

DOEpatents

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.

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

1997-01-01

28

Advances in ambient temperature secondary lithium cells  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

29

Bussing Structure In An Electrochemical Cell  

DOEpatents

A bussing structure for bussing current within an electrochemical cell. The bussing structure includes a first plate and a second plate, each having a central aperture therein. Current collection tabs, extending from an electrode stack in the electrochemical cell, extend through the central aperture in the first plate, and are then sandwiched between the first plate and second plate. The second plate is then connected to a terminal on the outside of the case of the electrochemical cell. Each of the first and second plates includes a second aperture which is positioned beneath a safety vent in the case of the electrochemical cell to promote turbulent flow of gasses through the vent upon its opening. The second plate also includes protrusions for spacing the bussing structure from the case, as well as plateaus for connecting the bussing structure to the terminal on the case of the electrochemical cell.

Romero, Antonio L. (Parkton, MD)

2001-06-12

30

Electrochemical cell having an alkali-metal-nitrate electrode  

DOEpatents

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.

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

1982-06-04

31

Chemically modified graphite for electrochemical cells  

DOEpatents

This invention relates to chemically modified graphite particles: (a) that are useful in alkali metal-containing electrode of a electrochemical cell comprising: (i) the electrode, (ii) a non-aqueous electrolytic solution comprising an organic aprotic solvent which solvent tends to decompose when the electrochemical cell is in use, and an electrically conductive salt of an alkali metal, and (iii) a counterelectrode; and (b) that are chemically modified with fluorine, chlorine, iodine or phosphorus to reduce such decomposition. This invention also relates to electrodes comprising such chemically modified graphite and a binder and to electrochemical cells containing such electrodes.

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

1998-01-01

32

Advances in ambient temperature secondary lithium cells  

NASA Technical Reports Server (NTRS)

The goal is to develop secondary lithium cells with a 100 Wh/kg specific energy capable of 1000 cycles at 50 percent DOD. The approach towards meeting this goal initially focused on several 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 achievable specific energy and cycle life. Major advancements to date in the development of Li-TiS2 cells are in the areas of cathode processing technology, mixed solvent electrolytes, and cell assembly. A summary is given of these advances.

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

1989-01-01

33

Boundary Layer Analysis of Membraneless Electrochemical Cells  

E-print Network

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 ...

Braff, William A.

34

Electrochemical cell for rebalancing REDOX flow system  

NASA Technical Reports Server (NTRS)

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.

Thaller, L. H. (inventor)

1979-01-01

35

Nanodisperse transition metal electrodes (NTME) for electrochemical cells  

SciTech Connect

Disclosed are transition metal electrodes for electrochemical cells using gel-state and solid-state polymers. The electrodes are suitable for use in primary and secondary cells. The electrodes (either negative electrode or positive electrode) are characterized by uniform dispersion of the transition metal at the nanoscale in the polymer. The transition metal moiety is structurally amorphous, so no capacity fade should occur due to lattice expansion/contraction mechanisms. The small grain size, amorphous structure and homogeneous distribution provide improved charge/discharge cycling performance, and a higher initial discharge rate capability. The cells can be cycled at high current densities, limited only by the electrolyte conductivity. A method of making the electrodes (positive and negative), and their usage in electrochemical cells are disclosed.

Striebel, Kathryn A.; Wen, Shi-Jie

1998-12-01

36

Nanodisperse transition metal electrodes (NTME) for electrochemical cells  

DOEpatents

Disclosed are transition metal electrodes for electrochemical cells using gel-state and solid-state polymers. The electrodes are suitable for use in primary and secondary cells. The electrodes (either negative electrode or positive electrode) are characterized by uniform dispersion of the transition metal at the nanoscale in the polymer. The transition metal moiety is structurally amorphous, so no capacity fade should occur due to lattice expansion/contraction mechanisms. The small grain size, amorphous structure and homogeneous distribution provide improved charge/discharge cycling performance, and a higher initial discharge rate capability. The cells can be cycled at high current densities, limited only by the electrolyte conductivity. A method of making the electrodes (positive and negative), and their usage in electrochemical cells are disclosed.

Striebel, Kathryn A. (Oakland, CA); Wen, Shi-Jie (Sunnyvale, CA)

2000-01-01

37

Textbook Error: Short Circuiting on Electrochemical Cell  

ERIC Educational Resources Information Center

Short circuiting an electrochemical cell is an unreported but persistent error in the electrochemistry textbooks. It is suggested that diagrams depicting a cell delivering usable current to a load be postponed, the theory of open-circuit galvanic cells is explained, the voltages from the tables of standard reduction potentials is calculated and…

Bonicamp, Judith M.; Clark, Roy W.

2007-01-01

38

An electrochemical rebalance cell for Redox systems  

NASA Technical Reports Server (NTRS)

An electrochemical rebalance cell for maintaining electrochemical balance, at the system level, of the acidified aqueous iron chloride and chromium chloride reactant solutions in the redox energy storage system was constructed and evaluated. The electrochemical reaction for the cathode is Fe(+3) + e(-) yields Fe(+2), and that for the anode is 1/2H2 yields H(+) + e(-). The iron (carbon felt) electrode and the hydrogen (platinized carbon) electrode are separated by an anion exchange membrane. The performance of the rebalance cell is discussed as well as the assembly of a single rebalance cell and multicell stacks. Various cell configurations were tested and the results are presented and discussed. The rebalance cell was also used to demonstrate its ability, as a preparative tool, for making high purity solutions of soluble reduced metal ionic species. Preparations of titanium, copper, vanadium and chromium ions in acidified solutions were evaluated.

Acevedo, J. C.; Stalnaker, D. K.

1983-01-01

39

Trends in cell-based electrochemical biosensors.  

PubMed

Cell-based electrochemical biosensors have contributed tremendously to the fields of biology, medicine, chemistry, pharmacology, and environmental science. With electrochemical transducers and whole cells as the recognition elements, these biosensors provide new horizons for biosensing and life science research. This review focuses on the research accomplishments on this topic over the last three years, and is divided into three sections according to the types of cellular responses. Our aim is to highlight how simple and sensitive electrochemical methods can be coupled with cells by virtue of the integration of interface control, nanotechnology and genetic engineering to generate new enabling technologies. Some specific examples to demonstrate how these sensors are useful in medicinal chemistry and drug design have also been discussed. It is hoped that this review can provide inspiration for the development of fast, selective, sensitive, and convenient detection and diagnosis platforms. PMID:19075660

Ding, Lin; Du, Dan; Zhang, Xueji; Ju, Huangxian

2008-01-01

40

Method for vacuum pressing electrochemical cell components  

NASA Technical Reports Server (NTRS)

Assembling electrochemical cell components using a bonding agent comprising aligning components of the electrochemical cell, applying a bonding agent between the components to bond the components together, placing the components within a container that is essentially a pliable bag, and drawing a vacuum within the bag, wherein the bag conforms to the shape of the components from the pressure outside the bag, thereby holding the components securely in place. The vacuum is passively maintained until the adhesive has cured and the components are securely bonded. The bonding agent used to bond the components of the electrochemical cell may be distributed to the bonding surface from distribution channels in the components. To prevent contamination with bonding agent, some areas may be treated to produce regions of preferred adhesive distribution and protected regions. Treatments may include polishing, etching, coating and providing protective grooves between the bonding surfaces and the protected regions.

Andrews, Craig C. (Inventor); Murphy, Oliver J. (Inventor)

2004-01-01

41

Electrochemical control of cell and tissue polarity.  

PubMed

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

Chang, Fred; Minc, Nicolas

2014-10-11

42

Heteroatom incorporated coke for electrochemical cell electrode  

DOEpatents

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.

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

1997-01-01

43

Method of constructing an improved electrochemical cell  

DOEpatents

An electrochemical cell construction features a novel co-extruded plastic electrode in an interleaved construction with a novel integral separator-spacer. Also featured is a leak and impact resistant construction for preventing the spill of corrosive materials in the event of rupture.

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

1984-10-09

44

Alkaline electrochemical cells and method of making  

NASA Technical Reports Server (NTRS)

Equilibrated cellulose ether membranes of increased electrolytic conductivity for use as separators in concentrated alkaline electrochemical cells are investigated. The method of making such membranes by equilibration to the degree desired in an aqueous alkali solution mantained at a temperature below about 10 C is described.

Hoyt, H. E.; Pfluger, H. L. (inventors)

1970-01-01

45

Electrochemical cell operation and system  

DOEpatents

Thermal control in fuel cell operation is affected through sensible heat of process gas by providing common input manifolding of the cell gas flow passage in communication with the cell electrolyte and an additional gas flow passage which is isolated from the cell electrolyte and in thermal communication with a heat-generating surface of the cell. Flow level in the cell gas flow passage is selected based on desired output electrical energy and flow level in the additional gas flow passage is selected in accordance with desired cell operating temperature.

Maru, Hansraj C. (Brookfield Center, CT)

1980-03-11

46

Cathode for an electrochemical cell  

DOEpatents

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.

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

47

Electrolyte for an electrochemical cell  

DOEpatents

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.

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

1997-01-28

48

Electrolyte for an electrochemical cell  

DOEpatents

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.

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

1997-01-01

49

Non-aqueous, rechargeable electrochemical cell  

SciTech Connect

Non-aqueous rechargeable electrochemical cell is described comprising a negative electrode, a positive electrode containing an active material and an electrolyte solution into which said electrodes are immersed; said negative electrode comprising lithium; said electrolyte solution comprising sulfur dioxide (SO[sub 2]) as solvent and at least one solute which is a lithium salt with an anion of a group 3A element halide; and said positive electrode comprising a lithium cobalt oxide as the active material.

Heitbaum, J.; Hambitzer, G.

1993-05-25

50

Electrochemical Cells(ChemPages Lab)  

NSDL National Science Digital Library

Electrochemical Cells: this is a resource in the collection "ChemPages Laboratory Resources". The cell design described in this module includes two solutions connected by salt bridge (piece of string) and two electrodes (metal strips) connected to a voltmeter. The ChemPages Laboratory Resources are a set of web pages that include text, images, video, and self check questions. The topics included are those that are commonly encountered in the first-year chemistry laboratory. They have been put together for use as both a pre-laboratory preparation tool and an in-laboratory reference source.

51

Cycle life test. [of secondary spacecraft cells  

NASA Technical Reports Server (NTRS)

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.

Harkness, J. D.

1977-01-01

52

Electrochemical Cell Design With A Hollow Gate  

DOEpatents

An electrochemical cell having a spiral winding around a central core, wherein the central core is provided with longitudinal grooves on its outer surface to facilitate electrolyte filing and accommodate overpressure. The core itself improves dissipation of heat generated along the center of the cell, and the hollow core design allows the cell core to have a larger radius, permitting the "jelly roll" winding to begin at a larger radius and thereby facilitate the initial turns of the winding by decreasing the amount of bending required of the electrode laminate at the beginning of the winding operation. The hollow core also provides mechanical support end-to-end. A pair of washers are used at each end of the cell to sandwich current collection tabs in a manner that improves electrical and thermal conductivity while also providing structural integrity.

Romero, Antonio (Parkton, MD); Oweis, Salah (Ellicott City, MD); Chagnon, Guy (Columbia, MD); Staniewicz, Robert (Hunt Valley, MD); Briscoe, Douglas (Westminster, MD)

2000-02-01

53

Partial-Vacuum-Gasketed Electrochemical Corrosion Cell  

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

54

A Model Approach to the Electrochemical Cell: An Inquiry Activity  

ERIC Educational Resources Information Center

In an attempt to address some student misconceptions in electrochemistry, this guided-inquiry laboratory was devised to give students an opportunity to use a manipulative that simulates the particulate-level activity within an electrochemical cell, in addition to using an actual electrochemical cell. Students are led through a review of expected…

Cullen, Deanna M.; Pentecost, Thomas C.

2011-01-01

55

Thermodynamic and Kinetic Properties of the Electrochemical Cell.  

ERIC Educational Resources Information Center

Describes basic characteristics of the electrochemical cell. Also describes basic principles of electrochemical procedures and use of these concepts to explain use of the term "primarily" in discussions of methods primarily responsive to equilibrium cell potential, bulk ohmic resistance, and the Faradaic impedance. (JN)

Smith, Donald E.

1983-01-01

56

Fuel Cell/Electrochemical Cell Voltage Monitor  

NASA Technical Reports Server (NTRS)

A concept has been developed for a new fuel cell individual-cell-voltage monitor that can be directly connected to a multi-cell fuel cell stack for direct substack power provisioning. It can also provide voltage isolation for applications in high-voltage fuel cell stacks. The technology consists of basic modules, each with an 8- to 16-cell input electrical measurement connection port. For each basic module, a power input connection would be provided for direct connection to a sub-stack of fuel cells in series within the larger stack. This power connection would allow for module power to be available in the range of 9-15 volts DC. The relatively low voltage differences that the module would encounter from the input electrical measurement connection port, coupled with the fact that the module's operating power is supplied by the same substack voltage input (and so will be at similar voltage), provides for elimination of high-commonmode voltage issues within each module. Within each module, there would be options for analog-to-digital conversion and data transfer schemes. Each module would also include a data-output/communication port. Each of these ports would be required to be either non-electrical (e.g., optically isolated) or electrically isolated. This is necessary to account for the fact that the plurality of modules attached to the stack will normally be at a range of voltages approaching the full range of the fuel cell stack operating voltages. A communications/ data bus could interface with the several basic modules. Options have been identified for command inputs from the spacecraft vehicle controller, and for output-status/data feeds to the vehicle.

Vasquez, Arturo

2012-01-01

57

Polyaniline secondary cells with ambient temperature molten salt electrolytes  

SciTech Connect

An Al/polyaniline (PAn) powder secondary cell with an AlCl[sub 3]-1-butylpyridinium chloride (BPC) or an AlCl[sub 3]-1-ethyl-3-methylimidazolium chloride (EMIC) electrolyte has been investigated. The configuration of the Al/PAn secondary cell with an acidic AlCl[sub 3]-EMIC electrolyte was: open-circuit voltage (OCV) = 1.7 V, discharge capacity = 42 Ah, charge/discharge efficiency = 90%. A 24% increase in the discharge capacity over a BPC system electrolyte is obtained. The difference was attributed to the electrolyte properties, i.e., conductivity and viscosity. In the basic EMIC system bath of 44.4 m/o AlCl[sub 3], the redox potential of PAn was less noble and the reaction current was large. A PAn/PAn secondary cell with the acidic AlCl[sub 3]-EMIC catholyte and the basic anolyte was proposed. The OCV showed 1.0 V and the PAn/PAn secondary cell was promising. A PAn prepared from a nonaqueous BPC system bath was more electrochemically active than that prepared from an aqueous bath. The optimum OCV, discharge capacity, and charge/discharge efficiency of the Al/PAn (from the BPC bath) were 1.6 V, 68 Ah/kg-PAn, and 99%, respectively.

Koura, Nobuyuki; Ejiri, Hirokazu; Takeishi, Kazuyuki (Tokyo Univ. of Science (Japan))

1993-03-01

58

Improving the electrochemical performance of SnO{sub 2} cathodes in lithium secondary batteries by doping with Mo  

SciTech Connect

Small-grain SnO{sub 2}, SnO{sub 2}/Mo (2%), and SnO{sub 2}/Mo (30%) samples were prepared by using low-temperature aqueous methods and tested as cathodes in secondary lithium batteries. Cells were cycled between 1.0 and 0.0 V. The best electrochemical performance was obtained from the Li/[SnO{sub 2}/Mo (2%)] cell, which retained 87% of its initial capacity (510 mAh/g) after 50 cycles; by contrast, the Li/SnO{sub 2} cell only retained 60% of its initial capacity (570 mAh/g). Significantly increased Mo contents caused the capacity to fade drastically.

Morales, J.; Sanchez, L. [Univ. de Cordoba (Spain). Lab. de Quimica Inorganica] [Univ. de Cordoba (Spain). Lab. de Quimica Inorganica

1999-05-01

59

Performance evaluation of electrochemical concentration cell ozonesondes  

NASA Technical Reports Server (NTRS)

Laboratory calibrations of more than a hundred electrochemical concentration cell (ECC) ozonesondes were determined relative to UV-photometry. The average intercept and slope, 0 plus or minus 5 nb and 0.96 plus or minus 0.06, respectively, indicate reasonable agreement with UV photometry, but with considerable variation from one ECC ozonesonde to another. The time required to reach 85% of the final reaction to a step-change in ozone concentration was found to average 51 seconds. Application of the individual calibrations to 20 sets of 1976 flight data reduced the average of the differences between ozonesonde and Dobson spectrophotometric measurements of total ozone from 3.9 to 1.3%. A similar treatment of a set of 10 1977 flight records improved the average ECC-Dobson agreement from -8.5 to -1.4%. Although systematic differences were reduced, no significant effect on the random variations was evident.

Torres, A. L.; Bandy, A. R.

1977-01-01

60

Evaluation program for secondary spacecraft cells  

NASA Technical Reports Server (NTRS)

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.

Harkness, J. D.

1978-01-01

61

Method for making an electrochemical cell  

DOEpatents

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.

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

1996-01-01

62

Method for making an electrochemical cell  

DOEpatents

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.

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

1996-04-23

63

Magnetic resonance imaging of electrochemical cells containing bulk metal.  

PubMed

The development of improved energy-storage devices, as well as corrosion prevention and metal-electrofinishing technologies, requires knowledge of local composition and transport behaviour in electrolytes near bulk metals, in situ and in real time. It remains a challenge to acquire such data and new analytical methods are required. Recent work shows that magnetic resonance imaging (MRI) is able to map concentration gradients and visualise electrochemical processes in electrochemical cells containing bulk metals. This recent work, along with the challenges, and solutions, associated with MRI of these electrochemical cells are reviewed. PMID:24789698

Britton, Melanie M

2014-06-23

64

Electrochemical cell having improved pressure vent  

DOEpatents

The electrochemical cell of the instant invention includes a case having a gas outlet, one or more positive electrodes positioned within the case, one or more negative electrodes positioned within the case electrode separators positioned between the positive and negative electrodes, electrolyte positioned within the case, and a pressure vent for releasing internal pressure occurring in the case to the surrounding atmosphere. The pressure vent is affixed to the case covering the gas outlet, the pressure vent includes a vent housing having a hollow interior area in gaseous communication with the surrounding atmosphere and the interior of the case via the gas outlet, a pressure release piston positioned within the hollow interior area, the pressure release piston sized to surround the gas outlet and having a seal groove configured to encapsulate all but one surface of a seal mounted within the seal groove, leaving the non-encapsulated surface of the seal exposed, and a compression spring positioned to urge the pressure release piston to compress the seal in the seal groove and block the gas outlet in the case.

Dean, Kevin (Pontiac, MI); Holland, Arthur (Troy, MI); Fillmore, Donn (Waterford, MI)

1993-01-01

65

Steel refining with an electrochemical cell  

DOEpatents

Apparatus is described 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 oxygen and 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. 2 figs.

Blander, M.; Cook, G.M.

1988-05-17

66

Method of doping interconnections for electrochemical cells  

DOEpatents

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.

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

1990-01-01

67

Miniaturized biological and electrochemical fuel cells: challenges and applications.  

PubMed

This paper discusses the fundamentals and developments of miniaturized fuel cells, both biological and electrochemical. An overview of microfluidic fuel cells, miniaturized microbial fuel cells, enzymatic biofuel cells, and implanted biofuel cells in an attempt to provide green energy and to power implanted microdevices is provided. Also, the challenges and applications of each type of fuel cell are discussed in detail. Most recent developments in fuel cell technologies such as novel catalysts, compact designs, and fabrication methods are reviewed. PMID:23503374

Yang, Jie; Ghobadian, Sasan; Goodrich, Payton J; Montazami, Reza; Hashemi, Nastaran

2013-09-14

68

Chemical oxygen demand sensor employing a thin layer electrochemical cell  

Microsoft Academic Search

A chemical oxygen demand sensor employing a thin layer electrochemical cell was constructed using a sandwich-type thin layer working electrode. The electrode was constructed by attaching face to face glass and copper plates separated by PTFE spacers to create an extremely shallow cell. After filling the cell by capillary action, it was possible to measure reproducibly the coulometric charge required

Kyong-Hoon Lee; Tomoko Ishikawa; Scott McNiven; Yoko Nomura; Satoshi Sasaki; Yoshiko Arikawa; Isao Karube

1999-01-01

69

UHV, Electrochemical NMR, and Electrochemical Studies of Platinum\\/Ruthenium Fuel Cell Catalysts  

Microsoft Academic Search

It is well-known that platinum\\/ruthenium fuel cell catalysts show enhanced CO tolerance compared to pure platinum electrodes, but the reasons are still being debated. We have combined cyclic voltammetry (CV), temperature programmed desorption (TPD), electrochemical nuclear magnetic resonance, and radio active labeling to probe the origin of the ruthenium enhancement in Pt electrodes modified through Ru deposition. The results prove

C. Lu; C. Rice; R. I. Masel; P. K. Babu; P. Waszczuk; H. S. Kim; E. Oldfield; A. Wieckowski

2002-01-01

70

Electrochemical cell utilizing molten alkali metal electrode-reactant  

DOEpatents

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.

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

1983-11-04

71

Wick-and-pool electrodes for electrochemical cell  

DOEpatents

An electrode system includes a reservoir of liquid-metal reactant, and a wick extending from a submersed location within the reservoir into the molten electrolyte of an electrochemical cell structure. The wick is flooded with the liquid metal and thereby serves as one electrode within the cell. This electrode system has application in high-temperature batteries employing molten alkali metals or their alloys as active material within an electrode submersed within a molten salt electrolyte. It also can be used in electrochemical cells where the purification, separation or electrowinning of liquid metals is accomplished.

Roche, Michael F. (Downers Grove, IL); Faist, Suzan M. (Haddonfield, NJ); Eberhart, James G. (Naperville, IL); Ross, Laurids E. (Naperville, IL)

1980-01-01

72

The Variation of Electrochemical Cell Potentials with Temperature  

ERIC Educational Resources Information Center

Electrochemical cell potentials have no simple relationship with temperature but depend on the interplay between the sign and magnitude of the isothermal temperature coefficient, dE[degrees]/dT, and on the magnitude of the reaction quotient, Q. The variations in possible responses of standard and non-standard cell potentials to changes in the…

Peckham, Gavin D.; McNaught, Ian J.

2011-01-01

73

Assessing corrosion problems in photovoltaic cells via electrochemical stress testing  

NASA Technical Reports Server (NTRS)

A series of accelerated electrochemical experiments to study the degradation properties of polyvinylbutyral-encapsulated silicon solar cells has been carried out. The cells' electrical performance with silk screen-silver and nickel-solder contacts was evaluated. The degradation mechanism was shown to be electrochemical corrosion of the cell contacts; metallization elements migrate into the encapsulating material, which acts as an ionic conducting medium. The corrosion products form a conductive path which results in a gradual loss of the insulation characteristics of the encapsulant. The precipitation of corrosion products in the encapsulant also contributes to its discoloration which in turn leads to a reduction in its transparency and the consequent optical loss. Delamination of the encapsulating layers could be attributed to electrochemical gas evolution reactions. The usefulness of the testing technique in qualitatively establishing a reliability difference between metallizations and antireflection coating types is demonstrated.

Shalaby, H.

1985-01-01

74

UHV, Electrochemical NMR, and Electrochemical Studies of Platinum/Ruthenium Fuel Cell C. Lu, C. Rice, and R. I. Masel*  

E-print Network

platinum electrodes, but the reasons are still being debated. We have combined cyclic voltammetry (CV tolerance of platinum fuel cell catalysts. Cyclic voltammetry (CV) is used to determine how the kineticsUHV, Electrochemical NMR, and Electrochemical Studies of Platinum/Ruthenium Fuel Cell Catalysts C

Lu, Chang

75

Continuous-feed electrochemical cell with nonpacking particulate electrode  

DOEpatents

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.

Cooper, John F. (Oakland, CA)

1995-01-01

76

Continuous-feed electrochemical cell with nonpacking particulate electrode  

DOEpatents

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.

Cooper, J.F.

1995-07-18

77

Systems, methods and computer-readable media for modeling cell performance fade of rechargeable electrochemical devices  

DOEpatents

A system includes an electrochemical cell, monitoring hardware, and a computing system. The monitoring hardware periodically samples performance characteristics of the electrochemical cell. The computing system determines cell information from the performance characteristics of the electrochemical cell. The computing system also develops a mechanistic level model of the electrochemical cell to determine performance fade characteristics of the electrochemical cell and analyzing the mechanistic level model to estimate performance fade characteristics over aging of a similar electrochemical cell. The mechanistic level model uses first constant-current pulses applied to the electrochemical cell at a first aging period and at three or more current values bracketing a first exchange current density. The mechanistic level model also is based on second constant-current pulses applied to the electrochemical cell at a second aging period and at three or more current values bracketing the second exchange current density.

Gering, Kevin L

2013-08-27

78

Electrochemical characteristics of graphite, coke and graphite/coke hybrid carbon as negative electrode materials for lithium secondary batteries  

NASA Astrophysics Data System (ADS)

Electrochemical characteristics of various carbon materials have been investigated for application as a negative electrode material in lithium secondary batteries with long cycle life. Natural graphite electrodes show large discharge capacity in a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC). However, their charge/discharge performance is largely influenced by electrolytes. There is a possibility that a rapid rise in the discharge potential of the natural graphite electrode at the end of the discharge would cause a side reaction such as decomposition of the electrolyte because of an unequal reaction over an electrode. In order to improve the cycle performance of natural graphite electrodes, mixtures of graphite and coke electrodes are prepared by adding coke to natural graphite. It is found that the mixture of graphite and coke electrode shows a better cycle performance than that of a natural graphite or coke electrode. The deterioration ratio of the mixture of graphite and coke negative electrode measured by using AA-type test cells is 0.057%/cycle up to the 500th cycle. The mixture of graphite and coke is a promising material for a negative electrode in long-life lithium secondary batteries for energy storage systems because of its excellent cycle performance and large discharge capacity.

Kida, Yoshinori; Yanagida, Katsunori; Funahashi, Atsuhiro; Nohma, Toshiyuki; Yonezu, Ikuo

79

Method of enhancing the wettability of boron nitride for use as an electrochemical cell separator  

DOEpatents

A felt or other fabric of boron nitride suitable for use as an interelectrode separator within an electrochemical cell is wetted with a solution containing a thermally decomposable organic salt of an alkaline earth metal. An aqueous solution of magnesium acetate is the preferred solution for this purpose. After wetting the boron nitride, the solution is dried by heating at a sufficiently low temperature to prevent rapid boiling and the creation of voids within the separator. The dried material is then calcined at an elevated temperature in excess of 400/sup 0/C to provide a coating of an oxide of magnesium on the surface of the boron nitride fibers. A fabric or felt of boron nitride treated in this manner is easily wetted by molten electrolytic salts, such as the alkali metal halides or alkaline earth metal halides, that are used in high temperature, secondary electrochemical cells.

McCoy, L.R.

1981-01-23

80

Reversible luminance decay in polymer light-emitting electrochemical cells  

NASA Astrophysics Data System (ADS)

The luminance decay of generic sandwich polymer light-emitting electrochemical cells has been investigated. Under constant current operation, the apparent luminance decay is caused by both the formation of non-emitting black spots, which decreases the active emitting area, and the in situ electrochemical doping, which quenches the luminescence of the light-emitting electrochemical cell film. The latter's effect on luminance, however, can be mostly reversed by letting the electrochemical doping relax. A dramatic recovery of luminance is observed when the device is stored without voltage bias and/or moderately heated between consecutive operations. The decay/recovery cycle can be repeated multiple times with little loss of luminance despite the high current density (167 mA/cm2) applied. At lower current density, a freshly made device loses less than 10% of its peak luminance after over 200 h of continuous operation. Polymer light-emitting electrochemical cells therefore possess vastly longer operating lifetime if allowed to recover from the effect of reversible doping.

Li, Xiaoyu; Gao, Jun; Liu, Guojun

2013-06-01

81

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

E-print Network

commercialisation, rechargeable Li-ion batteries are widely accepted, and are becoming the main power source electrode, both reacting towards Li through insertion/de- insertion reactions. Improvements capacity1 On the electrochemical reactivity and design of NiP2 negative electrodes for secondary Li

Boyer, Edmond

82

Evaluation program for secondary spacecraft cells  

NASA Technical Reports Server (NTRS)

A life cycle test of secondary electric batteries for spacecraft applications was conducted. A sample number of nickel cadmium batteries were subjected to general performance tests to determine the limit of their actual capabilities. Weaknesses discovered in cell design are reported and aid in research and development efforts toward improving the reliability of spacecraft batteries. A statistical analysis of the life cycle prediction and cause of failure versus test conditions is provided.

Christy, D. E.; Harkness, J. D.

1973-01-01

83

Topographical and electrochemical nanoscale imaging of living cells using voltage-switching mode scanning electrochemical microscopy  

PubMed Central

We describe voltage-switching mode scanning electrochemical microscopy (VSM-SECM), in which a single SECM tip electrode was used to acquire high-quality topographical and electrochemical images of living cells simultaneously. This was achieved by switching the applied voltage so as to change the faradaic current from a hindered diffusion feedback signal (for distance control and topographical imaging) to the electrochemical flux measurement of interest. This imaging method is robust, and a single nanoscale SECM electrode, which is simple to produce, is used for both topography and activity measurements. In order to minimize the delay at voltage switching, we used pyrolytic carbon nanoelectrodes with 6.5–100 nm radii that rapidly reached a steady-state current, typically in less than 20 ms for the largest electrodes and faster for smaller electrodes. In addition, these carbon nanoelectrodes are suitable for convoluted cell topography imaging because the RG value (ratio of overall probe diameter to active electrode diameter) is typically in the range of 1.5–3.0. We first evaluated the resolution of constant-current mode topography imaging using carbon nanoelectrodes. Next, we performed VSM-SECM measurements to visualize membrane proteins on A431 cells and to detect neurotransmitters from a PC12 cells. We also combined VSM-SECM with surface confocal microscopy to allow simultaneous fluorescence and topographical imaging. VSM-SECM opens up new opportunities in nanoscale chemical mapping at interfaces, and should find wide application in the physical and biological sciences. PMID:22611191

Takahashi, Yasufumi; Shevchuk, Andrew I.; Novak, Pavel; Babakinejad, Babak; Macpherson, Julie; Unwin, Patrick R.; Shiku, Hitoshi; Gorelik, Julia; Klenerman, David; Korchev, Yuri E.; Matsue, Tomokazu

2012-01-01

84

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

Microsoft Academic Search

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

Roger Rouillard; Michael K. Domroese; Joseph A. Hoffman; David D. Lindeman; Joseph-Robert-Gaetan Noel; Vern E. Radewald; Michel Ranger; Anthony Sudano; Jennifer L. Trice; Thomas A. Turgeon

2003-01-01

85

Engineering secondary cell wall deposition in plants.  

PubMed

Lignocellulosic biomass was used for thousands of years as animal feed and is now considered a great sugar source for biofuels production. It is composed mostly of secondary cell walls built with polysaccharide polymers that are embedded in lignin to reinforce the cell wall structure and maintain its integrity. Lignin is the primary material responsible for biomass recalcitrance to enzymatic hydrolysis. During plant development, deep reductions of lignin cause growth defects and often correlate with the loss of vessel integrity that adversely affects water and nutrient transport in plants. The work presented here describes a new approach to decrease lignin content while preventing vessel collapse and introduces a new strategy to boost transcription factor expression in native tissues. We used synthetic biology tools in Arabidopsis to rewire the secondary cell network by changing promoter-coding sequence associations. The result was a reduction in lignin and an increase in polysaccharide depositions in fibre cells. The promoter of a key lignin gene, C4H, was replaced by the vessel-specific promoter of transcription factor VND6. This rewired lignin biosynthesis specifically for vessel formation while disconnecting C4H expression from the fibre regulatory network. Secondly, the promoter of the IRX8 gene, secondary cell wall glycosyltransferase, was used to express a new copy of the fibre transcription factor NST1, and as the IRX8 promoter is induced by NST1, this also created an artificial positive feedback loop (APFL). The combination of strategies-lignin rewiring with APFL insertion-enhances polysaccharide deposition in stems without over-lignifying them, resulting in higher sugar yields after enzymatic hydrolysis. PMID:23140549

Yang, Fan; Mitra, Prajakta; Zhang, Ling; Prak, Lina; Verhertbruggen, Yves; Kim, Jin-Sun; Sun, Lan; Zheng, Kejian; Tang, Kexuan; Auer, Manfred; Scheller, Henrik V; Loqué, Dominique

2013-04-01

86

Electrode electrolyte interlayers containing cerium oxide for electrochemical fuel cells  

DOEpatents

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).

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

2000-01-01

87

Electrochemical photovoltaic cells 2-6 compound thin film electrodes  

Microsoft Academic Search

The program focused on developing stable, thin film II-VI compound electrodes with sunlight efficiencies of 10%, for use with aqueous polysulfide electrolyte in frontwall and backwall illuminated electrochemical photovoltaic cells. The main effort was directed towards establishing the relationships among processing of the thin films, resultant electronic properties, and I-V performance in order to produce electrodes with maximum power conversion

M. A. Russak; J. Reichman; J. Decarlo; C. Creter

1981-01-01

88

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

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.

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

89

Method of low temperature operation of an electrochemical cell array  

DOEpatents

A method is described for operating an electrochemical cell generator apparatus containing a generator chamber containing an array of cells having interior and exterior electrodes with solid electrolyte between the electrodes, where a hot gas contacts the outside of the cells and the generating chamber normally operates at over 850 C, where N[sub 2] gas is fed to contact the interior electrode of the cells in any case when the generating chamber temperature drops for whatever reason to within the range of from 550 C to 800 C, to eliminate cracking within the cells. 2 figures.

Singh, P.; Ruka, R.J.; Bratton, R.J.

1994-04-26

90

Method of low temperature operation of an electrochemical cell array  

DOEpatents

In the method of operating an electrochemical cell generator apparatus containing a generator chamber (20) containing an array of cells (12) having interior and exterior electrodes with solid electrolyte between the electrodes, where a hot gas (F) contacts the outside of the cells (12) and the generating chamber normally operates at over 850.degree. C., where N.sub.2 gas is fed to contact the interior electrode of the cells (12) in any case when the generating chamber (20) temperature drops for whatever reason to within the range of from 550.degree. C. to 800.degree. C., to eliminate cracking within the cells (12).

Singh, Prabhakar (Export, PA); Ruka, Roswell J. (Churchill Boro, PA); Bratton, Raymond J. (Delmont, PA)

1994-01-01

91

Facile and quantitative electrochemical detection of yeast cell apoptosis  

PubMed Central

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

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

2014-01-01

92

Method for making an electrochemical cell  

DOEpatents

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 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.

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

1996-10-22

93

Method for making an electrochemical cell  

DOEpatents

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.

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

1996-01-01

94

Thin film CdSe photoanodes for electrochemical photovoltaic cells  

Microsoft Academic Search

Electrochemical photovoltaic cells rely on the junction formed between a semiconductor and electrolyte to accomplish photovoltaic conversion. As a result, they offer certain technical features that make them an attractive alternative to all solid-state solar cells, especially if thin film photoelectrodes are used. This paper describes the fabrication and evaluation of thin film CdSe electrodes for use with sulfide\\/polysulfide electrolyte

M. A. Russak; J. Reichman; H. Witzke; S. K. Deb; S. N. Chen

1980-01-01

95

Vanadium-doped lithium thiochromite - Properties, crystal structure and electrochemical performance in rechargeable Li cells  

NASA Astrophysics Data System (ADS)

The physicochemical properties and crystal structure of vanadium-doped lithium thiochromite, produced by thermal synthesis in a sulfur melt and a subsequent delithiation in oxygen-containing aqueous suspension, are described. The compound is characterized by a rigid crystal structure, which can sustain the mechanical tensions developed during lithium intercalation and deintercalation upon cycling. The electrochemical performance of this compound as cathode material in lithium secondary cells, specific capacity of 0.15-0.16 mA h/g, mid-discharge voltage of 2.5 V, and cycling efficiency above 99 percent, make it attractive for practical applications.

Moshtev, R.; Geronov, Y.; Balkanov, I.; Puresheva, B.

1991-03-01

96

Selectable-Tip Corrosion-Testing Electrochemical Cell  

NASA Technical Reports Server (NTRS)

The figure depicts aspects of an electrochemical cell for pitting- corrosion tests of material specimens. The cell is designed to generate a region of corrosion having a pit diameter determined by the diameter of a selectable tip. The average depth of corrosion is controlled by controlling the total electric charge passing through the cell in a test. The cell is also designed to produce minimal artifacts associated with crevice corrosion. There are three selectable tips, having diameters of 0.1 in. (0.254 cm), 0.3 in. (0.762 cm), and 0.6 in. (1.524 cm), respectively.

Lomness, Janice; Hintze, Paul

2008-01-01

97

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

DOEpatents

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.

Gering, Kevin L.

2013-06-18

98

Thermodynamics of Electrochemical Cells Chemistry 223  

E-print Network

Cathode (reduction)Anode (oxidation) Cu Cu +2 e- e- Salt Bridge Fig. 1: The Galvanic or Daniels cell. Oxidation occurs at the anode, while reduction occurs at the cathode. For the compounds shown that functions as a battery, the so-called Galvanic or Daniels cell. Basically, when the switch is closed

Ronis, David M.

99

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

NASA Technical Reports Server (NTRS)

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.

Gross, S.

1977-01-01

100

Method of making gas diffusion layers for electrochemical cells  

DOEpatents

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.

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

2002-01-01

101

Fuel Cells and Electrochemical Energy Storage.  

ERIC Educational Resources Information Center

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)

Sammells, Anthony F.

1983-01-01

102

Composite bipolar plate for electrochemical cells  

DOEpatents

A bipolar separator plate for fuel cells consists of a molded mixture of a vinyl ester resin and graphite powder. The plate serves as a current collector and may contain fluid flow fields for the distribution of reactant gases. The material is inexpensive, electrically conductive, lightweight, strong, corrosion resistant, easily mass produced, and relatively impermeable to hydrogen gas. The addition of certain fiber reinforcements and other additives can improve the properties of the composite material without significantly increasing its overall cost.

Wilson, Mahlon S. (Los Alamos, NM); Busick, Deanna N. (Los Alamos, NM)

2001-01-01

103

Gas microsensors using cyclic voltammetry with a cermet electrochemical cell.  

SciTech Connect

The sensing characteristics of a cermet electrochemical cell, expressed as NiO|Pt|solid electrolyte|Pt were investigated by applying cyclic voltammetry to the Pt electrodes and measuring changes in ionic current through the solid electrolyte. Features of the current-voltage response (voltammograms) appear to depend uniquely on the type of gas exposed to the cell surface and the solid electrolyte material used. The novel sensors can selectively detect O{sub 2}, CO{sub 2}, and a variety of hydrocarbons. Performance characteristics such as selectivity, sensitivity, speed of response, and temperature dependence were also reported.

Shoemaker, E. L.; Vogt, M. C.; Dudek, F. J.; Turner, T.; Energy Systems

1997-07-15

104

Electrochemical behavior of niobium triselenide cathode in lithium secondary cells  

NASA Technical Reports Server (NTRS)

Niobium triselenide cathodes in Li ambient-temperature rechargeable batteries for space applications undergo a topotactic reaction, with three equivalents of Li at high positive potential furnishing high energy density. It also yields good electronic conductivity, a long life cycle, and high diffusivity for Li. An attempt is presently made to characterize the intercalation mechanism between Li and NbSe3 by means of an ac impedance study conducted at various charge stages in the process of SbSe3 reduction. An effort is also made to predict the charge state of NbSe3 nondestructively, on the basis of the impedance parameters.

Ratnakumar, B. V.; Di Stefano, S.; Bankston, C. P.

1988-01-01

105

Electrochemical cell apparatus having an exterior fuel mixer nozzle  

DOEpatents

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.

Reichner, P.; Doshi, V.B.

1992-12-08

106

Electrochemical cell apparatus having an exterior fuel mixer nozzle  

DOEpatents

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.

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

1992-01-01

107

Electrochemical storage cell based on polycrystalline silicon  

NASA Astrophysics Data System (ADS)

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.

Canfield, D.; Morrison, S. R.

1982-02-01

108

Exploratory studies on some electrochemical cell systems  

NASA Astrophysics Data System (ADS)

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.

Chaudhuri, Srikumar; Guha, D.

109

Electrochemical characterisation of fuel cell stack during cold start  

NASA Astrophysics Data System (ADS)

Fuel cell self start at negative temperature conditions is not an easy task due to the water produced by the reduction of oxygen at the cathode. This amount of water can turn into ice and block the reaction before the temperature inside the fuel cell reaches positive values. The mechanism of the physical process which leads to oxidant starvation phenomena when ice appears is not yet well identified. In order to obtain a deeper understanding of this problem, the article presents some experimental investigations conducted on a short fuel cell stack. These experiments simulate vehicle technology operated in cold start conditions not with the primary objective to reach a successful and rapid start-up but much rather to characterise and understand the cold start phenomena until starvation occurs. A number of polarisation curves, electrochemical spectroscopy and cyclic voltammetry measurements are done on the stack before, after and also during the cold starts experiments. It is observed that the process of drying and cooling down prior to cold start have a great impact on the electrochemical cathode area. The results obtained show the evolution of the stack behaviour during the low temperature operation with a slow production of frost. The consequence on the individual cells in terms of inhomogeneous degradation is highlighted.

Harel, F.; Bégot, S.; Wasterlain, S.; Candusso, D.

2011-05-01

110

Electrochemical Cell for Obtaining Oxygen from Carbon Dioxide Atmospheres  

NASA Technical Reports Server (NTRS)

To support human life on the Martian surface, an electrochemical device will be required to obtain oxygen from the carbon dioxide rich atmosphere. The electrolyte employed in such a device must be constructed from extremely thin, dense membranes to efficiently acquire the oxygen necessary to support life. A forming process used industrially in the production of multilayer capacitors and electronic substrates was adapted to form the thin membranes required. The process, known as the tape casting, involves the suspension consisting of solvents and binders. The suspension is passed under a blade, resulting in the production of ceramic membranes between 0.1 and 0.5 mm thick. Once fired, the stabilized zirconia membranes were assembled into the cell design by employing a zirconium phosphate solution as the sealing agent. The resulting ceramic-to-ceramic seals were found to be structurally sound and gas-tight. Furthermore, by using a zirconia-based solution to assemble the cell, the problem of a thermal expansion mismatch was alleviated. By adopting an industrial forming process to produce thin membranes, an electrochemical cell for obtaining oxygen from carbon dioxide was produced. The proposed cell design is unique in that it does not require a complicated manifold system for separating the various gases present in this process, nor does it require a series of complex electrical connections. Thus, the device can reliably obtain the vital oxygen supply from the toxic carbon dioxide atmosphere.

Hooker, Matthew; Rast, H. Edward; Rogers, Darren K.; Borja, Luis; Clark, Kevin; Fleming, Kimberly; Mcgurren, Michael; Oldaker, Tom; Sweet, Nanette

1989-01-01

111

Microfabricated Microbial Fuel Cell Arrays Reveal Electrochemically Active Microbes  

PubMed Central

Microbial fuel cells (MFCs) are remarkable “green energy” devices that exploit microbes to generate electricity from organic compounds. MFC devices currently being used and studied do not generate sufficient power to support widespread and cost-effective applications. Hence, research has focused on strategies to enhance the power output of the MFC devices, including exploring more electrochemically active microbes to expand the few already known electricigen families. However, most of the MFC devices are not compatible with high throughput screening for finding microbes with higher electricity generation capabilities. Here, we describe the development of a microfabricated MFC array, a compact and user-friendly platform for the identification and characterization of electrochemically active microbes. The MFC array consists of 24 integrated anode and cathode chambers, which function as 24 independent miniature MFCs and support direct and parallel comparisons of microbial electrochemical activities. The electricity generation profiles of spatially distinct MFC chambers on the array loaded with Shewanella oneidensis MR-1 differed by less than 8%. A screen of environmental microbes using the array identified an isolate that was related to Shewanella putrefaciens IR-1 and Shewanella sp. MR-7, and displayed 2.3-fold higher power output than the S. oneidensis MR-1 reference strain. Therefore, the utility of the MFC array was demonstrated. PMID:19668333

Cho, Younghak; de Figueiredo, Paul; Han, Arum

2009-01-01

112

Pore size engineering applied to starved electrochemical cells and batteries  

NASA Technical Reports Server (NTRS)

To maximize performance in starved, multiplate cells, the cell design should rely on techniques which widen the volume tolerance characteristics. These involve engineering capillary pressure differences between the components of an electrochemical cell and using these forces to promote redistribution of electrolyte to the desired optimum values. This can be implemented in practice by prescribing pore size distributions for porous back-up plates, reservoirs, and electrodes. In addition, electrolyte volume management can be controlled by incorporating different pore size distributions into the separator. In a nickel/hydrogen cell, the separator must contain pores similar in size to the small pores of both the nickel and hydrogen electrodes in order to maintain an optimum conductive path for the electrolyte. The pore size distributions of all components should overlap in such a way as to prevent drying of the separator and/or flooding of the hydrogen electrode.

Abbey, K. M.; Thaller, L. H.

1982-01-01

113

Method of electrode fabrication for solid oxide electrochemical cells  

DOEpatents

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.

Jensen, Russell R. (Murrysville, PA)

1990-01-01

114

ECC (Electrochemical Concentration Cell) ozonesonde observations at Mirny, Antarctica, during 1988  

NASA Technical Reports Server (NTRS)

Atmospheric ozone vertical distributions, air temperatures, and wind speed and direction data are presented for 40 balloon electrochemical concentration cell ozone soundings made at Mirny, Antarctica, in 1988.

Komhyr, W. D.; Lathrop, J. A.; Arbuzova, V. N.; Khattatov, V. U.; Nureyev, P. G.; Rudakov, V. V.; Zamyshlayev, I. V.

1989-01-01

115

Detection of radiation from electrochemical cell intensifying beta decay.  

PubMed

The predictions of relic neutrino existence and neutrino anomalous magnetic moment existence, as well as the solution of the Dirac equation for a neutral particle with an anomalous magnetic moment in the Coulomb field imply the existence of neutrino matter component. In this work the radiation intensifying (60)Co and (137)Cs beta decays by (0.42 ± 0.05)% and (0.160 ± 0.012)% has been detected from the end electrochemical cell. The radiation interaction cross-section with radioactive nuclei is more than 10(-30)cm(2). PMID:22728839

Muromtsev, V I; Veprev, D P

2012-08-01

116

Improving light-emitting electrochemical cells with ionic additives  

NASA Astrophysics Data System (ADS)

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.

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

2013-05-01

117

Battery paste compositions and electrochemical cells for use therewith  

DOEpatents

An improved battery paste composition and a lead-acid electrochemical cell which incorporates the composition. The cell includes a positive current collector and a negative current collector which are each coated with a paste containing one or more lead-containing compositions and a paste vehicle to form a positive plate and a negative plate. An absorbent electrolyte-containing separator member may also be positioned between the positive and negative plates. The paste on the positive current collector, the negative current collector, or both further includes a special additive consisting of polyvinylsulfonic acid or salts thereof which provides many benefits including improved battery cycle life, increased charge capacity, and enhanced overall stability. The additive also makes the pastes smoother and more adhesive, thereby improving the paste application process. The paste compositions of interest may be used in conventional flat-plate cells or in spirally wound batteries with equal effectiveness.

Olson, John B. (Boulder, CO)

1999-12-07

118

Battery paste compositions and electrochemical cells for use therewith  

DOEpatents

An improved battery paste composition and a lead-acid electrochemical cell which incorporates the composition are disclosed. The cell includes a positive current collector and a negative current collector which are each coated with a paste containing one or more lead-containing compositions and a paste vehicle to form a positive plate and a negative plate. An absorbent electrolyte-containing separator member may also be positioned between the positive and negative plates. The paste on the positive current collector, the negative current collector, or both further includes a special additive consisting of polyvinyl sulfonic acid or salts thereof which provides many benefits including improved battery cycle life, increased charge capacity, and enhanced overall stability. The additive also makes the pastes smoother and more adhesive, thereby improving the paste application process. The paste compositions of interest may be used in conventional flat-plate cells or in spirally wound batteries with equal effectiveness. 2 figs.

Olson, J.B.

1999-02-16

119

Battery paste compositions and electrochemical cells for use therewith  

DOEpatents

An improved battery paste composition and a lead-acid electrochemical cell which incorporates the composition. The cell includes a positive current collector and a negative current collector which are each coated with a paste containing one or more lead-containing compositions and a paste vehicle to form a positive plate and a negative plate. An absorbent electrolyte-containing separator member may also be positioned between the positive and negative plates. The paste on the positive current collector, the negative current collector, or both further includes a special additive consisting of polyvinylsulfonic acid or salts thereof which provides many benefits including improved battery cycle life, increased charge capacity, and enhanced overall stability. The additive also makes the pastes smoother and more adhesive, thereby improving the paste application process. The paste compositions of interest may be used in conventional flat-plate cells or in spirally wound batteries with equal effectiveness.

Olson, John B. (Boulder, CO)

1999-02-16

120

In vitro electrochemical corrosion and cell viability studies on nickel-free stainless steel orthopedic implants.  

PubMed

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

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

121

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

PubMed Central

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

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

122

Electrochemically Reduced Water Protects Neural Cells from Oxidative Damage  

PubMed Central

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

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

2014-01-01

123

Dynamic doping in bright and stable light emitting electrochemical cells.  

PubMed

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

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

2013-07-01

124

Scanning electrochemical microscopy of living cells: Different redox activities of nonmetastatic and metastatic human breast cells  

PubMed Central

Electrochemical methods have been widely used to monitor physiologically important molecules in biological systems. This report describes the first application of the scanning electrochemical microscope (SECM) to probe the redox activity of individual living cells. The possibilities of measuring the rate and investigating the pathway of transmembrane charge transfer are demonstrated. By this approach, significant differences are detected in the redox responses given by nonmotile, nontransformed human breast epithelial cells, breast cells with a high level of motility (engendered by overexpression of protein kinase C?), and highly metastatic breast cancer cells. SECM analysis of the three cell lines reveals reproducible differences with respect to the kinetics of charge transfer by several redox mediators. PMID:10963658

Liu, Biao; Rotenberg, Susan A.; Mirkin, Michael V.

2000-01-01

125

Fabrication of solid oxide fuel cell by electrochemical vapor deposition  

DOEpatents

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.

Riley, B.; Szreders, B.E.

1988-04-26

126

Fabrication of solid oxide fuel cell by electrochemical vapor deposition  

DOEpatents

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.

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

1989-01-01

127

Stabilizing metal components in electrodes of electrochemical cells  

DOEpatents

Disclosed is a method of reducing the removal or transfer into a gas phase of a current carrying metal in an apparatus, such as an electrochemical cell 2 having a porous fuel electrode 6 containing metal particles 11, where the metal is subject to removal or transfer into a gaseous phase, the method characterized in that (1) a metal organic compound that decomposes to form an electronically conducting oxide coating when heated is applied to the metal and porous electrode, and (2) the compound on the metal is then heated to a temperature sufficient to decompose the compound into an oxide coating 13 by increasing the temperature at a rate that is longer than 1 hour between room temperature and 600.degree. C., resulting in at least one continuous layer 13, 14 of the oxide coating on the metal.

Spengler, Charles J. (Murrysville, PA); Ruka, Roswell J. (Churchill Borough, PA)

1989-01-01

128

Photosynthetic electrochemical cell charging infrastructure versus photovoltaic cell charging infrastructure for future electric vehicles  

Microsoft Academic Search

The automotive industry is migrating towards all- electric and plug-in hybrid electric vehicles. Nevertheless conventional energy, in the form of thermal power and nuclear power, are used to power these vehicles which are not green and clean. The photosynthetic electrochemical cell (PEC) is one of the alternative energy resources for EVs and PHEVs. It could prove to be the ideal

Arvind Vyas Ramanan; Muthukumaran Pakirisamy; Sheldon S. Williamson

2011-01-01

129

Histochemical staining of Arabidopsis thaliana secondary cell wall elements.  

PubMed

Arabidopsis thaliana is a model organism commonly used to understand and manipulate various cellular processes in plants, and it has been used extensively in the study of secondary cell wall formation. Secondary cell wall deposition occurs after the primary cell wall is laid down, a process carried out exclusively by specialized cells such as those forming vessel and fiber tissues. Most secondary cell walls are composed of cellulose (40-50%), hemicellulose (25-30%), and lignin (20-30%). Several mutations affecting secondary cell wall biosynthesis have been isolated, and the corresponding mutants may or may not exhibit obvious biochemical composition changes or visual phenotypes since these mutations could be masked by compensatory responses. Staining procedures have historically been used to show differences on a cellular basis. These methods are exclusively visual means of analysis; nevertheless their role in rapid and critical analysis is of great importance. Congo red and calcofluor white are stains used to detect polysaccharides, whereas Mäule and phloroglucinol are commonly used to determine differences in lignin, and toluidine blue O is used to differentially stain polysaccharides and lignin. The seemingly simple techniques of sectioning, staining, and imaging can be a challenge for beginners. Starting with sample preparation using the A. thaliana model, this study details the protocols of a variety of staining methodologies that can be easily implemented for observation of cell and tissue organization in secondary cell walls of plants. PMID:24894795

Pradhan Mitra, Prajakta; Loqué, Dominique

2014-01-01

130

Cycle life test of secondary spacecraft cells  

NASA Technical Reports Server (NTRS)

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.

Harkness, J. D.

1980-01-01

131

Cycle life test of secondary spacecraft cells  

SciTech Connect

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 cycled 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.

Harkness, J.D.

1980-04-01

132

Fabrication and characterization of nanostructured ZnO thin film microdevices by scanning electrochemical cell microscopy.  

PubMed

Scanning electrochemical cell microscopy (SECCM) was proven to be a prospective microfabrication method for the in situ synthesis and multiscale assembly of functional nanomaterials into microdevices. Nanostructured ZnO thin film was synthesized and assembled by SECCM, which has excellent electrochemical capacitance and electronic I-V properties. PMID:23089918

Zhan, Dongping; Yang, Dezhi; Zhu, Yiliang; Wu, Xueru; Tian, Zhong-Qun

2012-12-01

133

MEMS-based dynamic cell-to-cell culture platforms using electrochemical surface modifications  

NASA Astrophysics Data System (ADS)

MEMS-based biological platforms with the capability of both spatial placements and time releases of living cells for cell-to-cell culture experiments have been designed and demonstrated utilizing electrochemical surface modification effects. The spatial placement is accomplished by electrochemical surface modification of substrate surfaces to be either adhesive or non-adhesive for living cells. The time control is achieved by the electrical activation of the selective indium tin oxide co-culture electrode to allow the migration of living cells onto the electrode to start the cell-to-cell culture studies. Prototype devices have a three-electrode design with an electrode size of 50 × 50 µm2 and the separation gaps of 2 µm between them. An electrical voltage of -1.5 V has been used to activate the electrodes independently and sequentially to demonstrate the dynamic cell-to-cell culture experiments of NIH 3T3 fibroblast and Madin Darby canine kidney cells. As such, this MEMS platform could be a basic yet versatile tool to characterize transient cell-to-cell interactions.

Chang, Jiyoung; Yoon, Sang-Hee; Mofrad, Mohammad R. K.; Lin, Liwei

2011-05-01

134

Electrochemical properties of Li-Cr-Mn-O cathode materials for lithium secondary batteries  

NASA Astrophysics Data System (ADS)

Layered Li-Cr-Mn-O cathode materials related to the LiCrO 2-LiMnO 2-Li 2MnO 3 solid solution have been synthesized by the mixed-hydroxide method. The materials are characterized by X-ray diffraction (XRD) and electrochemical techniques. The XRD patterns reveal that samples are a solid solution of hexagonal and monoclinic structures. The most promising cathode material in terms of high capacity and stable cycling performance exhibits the average discharge capacity of 204 mAh g -1 between 2.5 and 4.5 V versus Li/Li +.

Kim, Kwang-Soo; Lee, Seung-Won; Moon, Hee-Soo; Kim, Hyun-Joong; Cho, Byung-Won; Cho, Won-Il; Choi, Jin-Beom; Park, Jong-Wan

135

Evaluation program for secondary spacecraft cells  

NASA Technical Reports Server (NTRS)

The cycle life tests to determine the performance capabilities of packs of cells under different loads and temperature conditions are reported. Results are summarized, and the failure of 14 failed cells is analyzed. It was found that the main cause of failure was separator deterioration and migration of the negative plate material.

Harkness, J. D.

1975-01-01

136

Electrochemical Characterization of Solid Acid Fuel Cell Electrodes  

NASA Astrophysics Data System (ADS)

The quest for high-efficiency, high-power output fuel cells can be largely equated to the quest for high-performance components (anode, cathode, electrolyte). Solid Acid electrolytes, notably CsH2PO4, have been demonstrated to be affordable, stable, excellent ion conductors, and impermeable to parasitic fuel cross-over. Moreover, they operate at a temperature `sweet-spot' high enough to promote electrode kinetics and low enough to enable low-cost infrastructure. Fuel cell devices based on these materials are known to be limited, however, by electrode losses---even with high platinum loading. Improving the performance and lowering the cost of these components is necessary if such devices are to be considered viable alternatives. In this work, the primary focus was the development of electrochemical characterization approaches. In doing so, we investigated electrode losses through steady-state and time-dependent electrochemical characterization and identified the primary rate limiting process and mechanism as oxygen reduction at the cathode. To characterize anode kinetics, new testing approaches were implemented which employed robust, asymmetric electrode geometries to isolate electrode kinetics without the inclusion of a reference electrode. These geometries' isolation efficacy was assessed by numerical computation---the results of which were leveraged into an explicitly defined, material-agnostic tool to evaluate asymmetric electrode geometries. While for platinum, the cathode mechanism was shown to be insensitive to the microstructures tested, the mechanism of hydrogen reduction/oxidation was seen to vary between nanoscale powder and microscale defined electrodes---reconfirming the importance of rigorous testing approaches. Asymmetric electrode geometries with defined microstructures allowed direct characterization and comparative evaluation of non-platinum candidates for both the anode and the cathode. On the anode, palladium was over an order of magnitude more active than platinum and nickel, which exhibited a comparable activity. Palladium and silver were shown to be stable cathode materials, though less active than platinum. As a demonstration of the developed methodology's flexibility, a palladium-silver alloy was synthesized and tested. The tools and methodologies developed in this work enable the rapid and flexible screening of electrodes for solid acid fuel cells.

Sasaki, Kenji Alexander

137

Time-course correlation of biofilm properties and electrochemical performance in single-chamber microbial fuel cells  

E-print Network

Time-course correlation of biofilm properties and electrochemical performance in single 2010 Keywords: Microbial fuel cell Electricity Biofilm Electrochemical impedance spectroscopy a b s t r under identical conditions. While voltage stabilized within 4 days, anode biofilms continued growing

Mench, Matthew M.

138

Air electrode material for high temperature electrochemical cells  

DOEpatents

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.

Ruka, Roswell J. (Churchill Boro, PA)

1985-01-01

139

Supported liquid membrane electrochemical separators  

DOEpatents

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.

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

1986-01-01

140

Solid electrolyte-electrode system for an electrochemical cell  

DOEpatents

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.

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

1995-01-01

141

Solid electrolyte-electrode system for an electrochemical cell  

DOEpatents

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.

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

1995-04-04

142

ECC (electrochemical concentration cell) ozonesonde observations at South Pole, Antarctica, during 1987. Data report  

SciTech Connect

Atmospheric ozone vertical distributions, air temperatures, and wind speed and wind direction data are presented for 76 balloon electrochemical concentration cell (ECC) ozonesonde soundings made at South Pole, Antarctica, in 1987.

Komhyr, W.D.; Franchois, P.R.; Kuester, S.E.; Reitelback, P.J.; Fanning, M.L.

1988-03-01

143

Electrochemical Photovoltaic Cells II-VI Compound Thin Film Electrodes. Annual Report, June 1980-June 1981.  

National Technical Information Service (NTIS)

This year's program has focused on developing stable, thin film II-VI compound electrodes with sunlight efficiencies of 10%, for use with aqueous polysulfide electrolyte in frontwall and backwall illuminated electrochemical photovoltaic cells. The main ef...

M. A. Russak, J. Reichman, J. DeCarlo, C. Creter

1981-01-01

144

Direct In Vivo Electrochemical Detection of Haemoglobin in Red Blood Cells  

E-print Network

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 ...

Toh, Rou Jun

145

Electrochemical machining analysis on grid cathode composed of square cells  

NASA Astrophysics Data System (ADS)

During the electrochemical machining (ECM), the cathodes designed by the existing methods are mainly unitary cathodes, which can be only used to produce the workpieces with the same shapes. However, there are few researches on designing cathodes for machining the different workpieces with the different surfaces. This paper presents the grid cathode composed of the square cells to produce the workpieces with different shapes. Three types of the square cells, 2.5 mm×2.5 mm, 3 mm×3 mm, and 4 mm×4 mm, are utilized to construct the plane, the slant, and the blade cathode. The material of the cathode and the anode is CrNi18Ti9, and the ingredient of electrolyte is 15% NaCl and 15% NaNO3. The machining equilibrium machining current and time are acquired and analyzed, the machining process and the workpiece quality are compared between using the grid cathode and the unitary cathode. Moreover, the machining errors on the workpiece surface are measured and analyzed, and the error reasons are traced and discussed to obtain the better surface quality of the workpiece. The experiment and analysis results show that the grid cathode can be used to manufacture the workpieces with complex shapes in certain range of the error. The workpiece quality improves with the size of the square cell being reduced, and if the square element is small enough, the workpiece quality is almost equal to the one machined by the unitary cathode. The proposed research realizes a single cathode machining the different workpieces with the different surfaces.

Lu, Yonghua; Liu, Kai; Zhao, Dongbiao

2013-07-01

146

Life testing of secondary Ag-Zn cells  

NASA Astrophysics Data System (ADS)

Testing on a variety of secondary silver-zinc (Ag-Zn) cells has continued at MSFC for the past six years. The latest test involves a 350 amp/hr cell design that was cycled for 12 months and has undergone approximately 5400 low-earth-orbit cycles as well as 12 deep discharges. This test is not only a life test of these cells, but it also addresses different methods of storing the cells between deep discharges. Also, impedance measurements are made on one of the packs during periodic deep discharges. It is hoped that this will give a good correlation between the health of a cell and its impedance.

Brewer, Jeffrey C.; Doreswamy, Rajiv

1991-05-01

147

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

PubMed

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

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

148

Algorithm Development for Electrochemical Impedance Spectroscopy Diagnostics in PEM Fuel Cells  

E-print Network

Algorithm Development for Electrochemical Impedance Spectroscopy Diagnostics in PEM Fuel Cells Abstract The purpose of this work is to develop algorithms to identify fuel cell faults using-board fuel cell diagnostic hardware. Impedance can identify faults that cannot be identified solely by a drop

Victoria, University of

149

Electrochemical and spectroscopic studies of fuel cell reactions  

NASA Astrophysics Data System (ADS)

Fuel cells, especially proton exchange membrane fuel cells (PEMFCs) are expected soon to become a major source of clean energy. However, the sluggish kinetics of the fuel cell reactions, i.e., the fuel oxidation and oxygen reduction, hinders the wide-spread application of PEMFCs. These problems prompted our studies to focus on elucidating the nature of the reaction intermediates during the oxidation of fuels and the reduction of oxygen on electrocatalysts, and understanding the mechanisms of these reactions. The results from these studies will provide basic information for designing new electrocatalysts. In this dissertation, the oxidation reactions of ethanol and dimethyl ether (DME) on Pt were investigated by the surface enhanced infrared absorption spectroscopy with an attenuated total reflection configuration (ATR-SEIRAS). Various reaction intermediates were detected and their electrochemical behaviors were studied. We also benefited from advantages of the ATR-SEIRAS technique and observed superoxide anion (O2-) and hydrogen peroxide anion (H2-) as the intermediates in the oxygen reduction reaction (ORR) on Pt and Au electrodes for the first time. The other main goal of this study is design of new electrocatalysts for ORR with low cost and high activity. Two novel electrocatalysts were developed. One is Pt monolayer electrocatalysts consisting of a Pt monolayer formed by a red-ox replacement of the Cu monolayer by Pt atoms on non-noble metal-noble metal core-shell nanoparticles. In such catalyst, the total noble mass activity of the catalyst was 2--6 times larger that of commercial Pt catalyst. Another way of lowering the cost of catalysts and enhancing the ORR activity involves alloying less expensive noble metals with other non-noble elements. In this dissertation, the nano-structured Pd based alloy electrocatalysts have been explored. The results showed that their ORR activities surpass that of commercial Pt. The density functional theory (DFT) calculations were carried out to address the possible mechanisms for the observed enhancement. The volcano-type dependence of the ORR activity on the d-band center of the noble metal overlayer was established. These results indicate a way for designing new catalysts with greatly improved properties.

Shao, Minhua

150

Electrochemical cell chip to detect environmental toxicants based on cell cycle arrest technique.  

PubMed

A cell-based chip was recently developed and shown to be an effective in vitro tool for analyzing effect of environmental toxin on target cells. However, common cell chips are inappropriate for the detection of multiple environmental toxins. Here, we fabricated a neural cell chip to detect different cellular responses induced by BPA (bisphenol-A) and PCB (poly chlorinated biphenyl). This approach was based on an electrochemical method using a cell cycle-arrest technique. Neural cells were synchronized at the synthesis phase by treatment with thymidine, which results in a sharp reduction peak when compared to unsynchronized cells. The fabricated chip containing 50% G1/S and 50% G2/M phase cells was used to determine the effects of environmental toxins on neural cancer cells. At the end, the cell-chips could be used to assess both BPA and PCB toxicity that the cells were completely synchronized at the G1/S and G2/M phase. The proposed neural cell chip can be a useful tool for biosensors to evaluate easily and sensitively multiple effects of environmental toxicants on target cells. PMID:22959010

Kafi, Md Abdul; Yea, Cheol-Heon; Kim, Tae-Hyung; Yagati, Ajay Kumar; Choi, Jeong-Woo

2013-03-15

151

Electrochemical studies of graphitized mesocarbon microbeads as an anode in lithium-ion cells  

Microsoft Academic Search

The electrochemical performance of negative electrodes (anodes) made from mesocarbon microbeads (MCMB) in lithium-ion cells has been studied systematically via a variety of electrochemical techniques. The MCMB anodes have a stable lithium intercalation capacity of 325mAhg?1 on high-rate charge–discharge cycling. Cyclic voltammetry shows only one reduction peak and one oxidation peak, which correspond to lithium-ion intercalation and de-intercalation, respectively. The

Jane Yao; G. X. Wang; Jung-ho Ahn; H. K. Liu; S. X. Dou

2003-01-01

152

Performance characteristics of ambient temperature secondary lithium cells  

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

153

Human natural killer cell development in secondary lymphoid tissues.  

PubMed

For nearly a decade it has been appreciated that critical steps in human natural killer (NK) cell development likely occur outside of the bone marrow and potentially necessitate distinct microenvironments within extramedullary tissues. The latter include the liver and gravid uterus as well as secondary lymphoid tissues such as tonsils and lymph nodes. For as yet unknown reasons these tissues are naturally enriched with NK cell developmental intermediates (NKDI) that span a maturation continuum starting from an oligopotent CD34(+)CD45RA(+) hematopoietic precursor cell to a cytolytic mature NK cell. Indeed despite the detection of NKDI within the aforementioned tissues, relatively little is known about how, why, and when these tissues may be most suited to support NK cell maturation and how this process fits in with other components of the human immune system. With the discovery of other innate lymphoid subsets whose immunophenotypes overlap with those of NKDI, there is also need to revisit and potentially re-characterize the basic immunophenotypes of the stages of the human NK cell developmental pathway in vivo. In this review, we provide an overview of human NK cell development in secondary lymphoid tissues and discuss the many questions that remain to be answered in this exciting field. PMID:24661538

Freud, Aharon G; Yu, Jianhua; Caligiuri, Michael A

2014-04-01

154

Comparison of High-Throughput Electrochemical Methods for Testing Direct Methanol Fuel Cell Anode Electrocatalysts  

E-print Network

and carbon dioxide.2 At the cathode, oxygen and protons are reduced to water.3 DMFCs could in principleComparison of High-Throughput Electrochemical Methods for Testing Direct Methanol Fuel Cell Anode The screening and testing of fuel cell electrocatalysts often involves comparisons under conditions that do

155

Electrochemical conversion of switchgrass and poplar in molten carbonate direct carbon fuel cell  

Microsoft Academic Search

One way of sustaining fuel cell technology is using renewable and sustainable energy means provided by biomass. This paper explores switchgrass and poplar in a molten carbonate electrolyte direct carbon fuel cell. It investigates their electrochemical conversions and provides results of power density, current density, open circuit voltage and other parameters. The biomasses were pyrolysed at 800°C to produce carbon

Olalekan Adeniyi

2012-01-01

156

Electrochemical models for the discharge characteristics of the nickel cadmium cell  

NASA Technical Reports Server (NTRS)

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.

Spritzer, M. S.

1981-01-01

157

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

ERIC Educational Resources Information Center

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

Ivey, Michelle M.; Smith, Eugene T.

2008-01-01

158

A Multilayer MEMS Platform for Single-Cell Electric Impedance Spectroscopy and Electrochemical Analysis  

Microsoft Academic Search

The fabrication and characterization of a micro- chamber electrode array for electrical and electrochemical studies of individual biological cells are presented. The geometry was tailored specifically for measurements from sensory hair cells isolated from the cochlea of the mammalian inner ear. Conventional micro- electromechanical system (MEMS) fabrication techniques were combined with a heat-sealing technique and polydimethylsiloxane micromolding to achieve a

Gregory M. Dittami; H. Edward Ayliffe; Curtis S. King; Richard D. Rabbitt

2008-01-01

159

Model-based predictive diagnostics for electrochemical energy sources  

Microsoft Academic Search

The model-based effort described here is focused on predictive diagnostics for primary and secondary batteries. However, this novel approach can also be applied to other electrochemical energy sources such as fuel cells. This method is based on accurate parametric modeling of the transport mechanisms within the battery. This system knowledge was used for the careful development of electrochemical and thermal

James D. Kozlowski; Carl S. Byington; Amulya K. Garga; Matthew J. Watson; Todd A. Hay

2001-01-01

160

A zoom into the nanoscale texture of secondary cell walls  

PubMed Central

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

2014-01-01

161

Nano-Bio Electrochemical Interfacing-Linking Cell Biology and Micro-Electronics  

NASA Astrophysics Data System (ADS)

Integration of biological substance within electronic devices is an innovative and challenging area combining recent progress in molecular biology and micro technology. First, we introduce the concept of integrating living cells with Micro Electro Mechanical Systems (MEMS). Following a brief overview on "whole cell based biosensors" we describe the design, fabrication, and process of a biocompatible electrochemical "Lab-on-a-Chip" system. Demonstrating the application of electrochemical interfacing based whole cell bio chips, we present two different configurations: a. integration of prokaryotic cells (bacteria) for water toxicity detection, and b. integration of eukaryotic cells (human colon cancer cells) for rapid evaluation of the effectiveness of drug treatments. Both applications, with either microbes or mammalian cells integrated onto MEMS based biochips with liquid volume in the range of 100 nL-1 ?L, function well and yield a detectable signal much higher than noise level after few minutes.

Shacham-Diamand, Y.; Popovtzer, R.; Rishpon, Y.

162

Electrochemical behavior of CrN coating for polymer electrolyte membrane fuel cell  

NASA Astrophysics Data System (ADS)

CrN films on a bipolar plate in polymer electrolyte membrane fuel cells have several advantages owing to their excellent corrosion resistance and mechanical properties. Three CrN samples deposited at various radio frequency (RF) powers by RF magnetron sputtering were evaluated under potentiodynamic, potentiostatic and electrochemical impedance spectroscopy conditions. The electrochemical impedance spectroscopy data were monitored for 168 h in a corrosive environment at 70 °C to determine the coating performance at +600 mVSCE under simulated cathodic conditions in a polymer electrolyte membrane fuel cell. The electrochemical behavior of the coatings increased with decreasing RF power. CrN films on the AISI 316 stainless steel substrate showed high protective efficiency and charge transfer resistance, i.e. increasing corrosion resistance with decreasing RF power. X-ray diffraction confirmed the formation of a CrN(200) preferred orientation at low RF power.

Nam, N. D.; Park, I. J.; Kim, J. G.; Tai, P. H.; Yoon, D. H.

2010-05-01

163

Combinatorial electrochemical cell array for high throughput screening of micro-fuel-cells and metal/air batteries  

NASA Astrophysics Data System (ADS)

An electrochemical cell array was designed that contains a common air electrode and 16 microanodes for high throughput screening of both fuel cells (based on polymer electrolyte membrane) and metal/air batteries (based on liquid electrolyte). Electrode materials can easily be coated on the anodes of the electrochemical cell array and screened by switching a graphite probe from one cell to the others. The electrochemical cell array was used to study direct methanol fuel cells (DMFCs), including high throughput screening of electrode catalysts and determination of optimum operating conditions. For screening of DMFCs, there is about 6% relative standard deviation (percentage of standard deviation versus mean value) for discharge current from 10to20mA/cm2. The electrochemical cell array was also used to study tin/air batteries. The effect of Cu content in the anode electrode on the discharge performance of the tin/air battery was investigated. The relative standard deviations for screening of metal/air battery (based on zinc/air) are 2.4%, 3.6%, and 5.1% for discharge current at 50, 100, and 150mA/cm2, respectively.

Jiang, Rongzhong

2007-07-01

164

Sulfur tolerant composite cermet electrodes for solid oxide electrochemical cells  

DOEpatents

An electrochemical apparatus is made containing an exterior electrode bonded to the exterior of a tubular, solid, oxygen ion conducting electrolyte where the electrolyte is also in contact with an interior electrode, said exterior electrode comprising particles of an electronic conductor contacting the electrolyte, where a ceramic metal oxide coating partially surrounds the particles and is bonded to the electrolyte, and where a coating of an ionic-electronic conductive material is attached to the ceramic metal oxide coating and to the exposed portions of the particles.

Isenberg, Arnold O. (Pittsburgh, PA)

1987-01-01

165

Electrochemical cell utilizing a mixture of phosphorus oxychloride and a low freezing solvent as the electrolyte  

Microsoft Academic Search

An electrochemical cell having an alkali metal anode; a cathode selected from the group consisting of halogens, metal halides, Group VI A elements and compounds thereof with metallic elements; and an electrolyte containing an inorganic solvent system and a solute dissolved in the solvent system. The solvent system comprises a mixture of phosphorus oxychloride, and a low freezing solvent selected

Auborn

1984-01-01

166

Scanning Electrochemical Microscopy: Detection of Human Breast Cancer Cells by Redox Environment  

Microsoft Academic Search

Scanning electrochemical microscopy (SECM) can be used to measure the redox activity of individual human breast cells. A chemical mediator (e.g. quinone) that rapidly crosses the membrane participates in intracellular redox reactions that are recorded on a microsecond timescale by an ultramicroelectrode positioned close to the membrane. Measurements of redox reactivity yield rate constants that are different for cancerous and

Susan A. Rotenberg; Michael V. Mirkin

2004-01-01

167

An electrochemical-based fuel-cell model suitable for electrical engineering automation approach  

Microsoft Academic Search

This paper presents a dynamic electrochemical model for representation, simulation, and evaluation of performance of small size generation systems emphasizing particularly proton exchange membrane fuel-cell (PEMFC) stacks. The results of the model are used to predict the output voltage, efficiency, and power of FCs as a function of the actual load current and of the constructive and operational parameters of

Jeferson M. Corrêa; Felix A. Farret; Luciane N. Canha; Marcelo G. Simões

2004-01-01

168

Electrochemical photovoltaic cells II-VI compound thin film electrodes. Annual report, June 1980June 1981  

Microsoft Academic Search

This year's program has focused on developing stable, thin film II-VI compound electrodes with sunlight efficiencies of 10%, for use with aqueous polysulfide electrolyte in frontwall and backwall illuminated electrochemical photovoltaic cells. The main effort has been directed towards establishing the relationships among processing of the thin films, resultant electronic properties, and I-V performance in order to produce electrodes with

M. A. Russak; J. Reichman; J. DeCarlo; C. Creter

1981-01-01

169

Electrochemical Photovoltaic and Photoelectrochemical Storage Cells Based on II-IV Polycrystalline Thin-Film Materials.  

National Technical Information Service (NTIS)

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 ...

W. L. Wallace

1983-01-01

170

J. Electrochem. Soc., in press (1998) MicroMacroscopic Coupled Modeling of Batteries and Fuel Cells  

E-print Network

1 J. Electrochem. Soc., in press (1998) Micro­Macroscopic Coupled Modeling of Batteries and Fuel materials and interface morphology and chemistry, has been developed for advanced batteries and fuel cells­cadmium and nickel­metal hydride batteries are carried out. The micro­macroscopic model can be used to explore

Wang, Chao-Yang

171

J. Electrochem. Soc., in press (1998) Micro-Macroscopic Coupled Modeling of Batteries and Fuel Cells  

E-print Network

1 J. Electrochem. Soc., in press (1998) Micro-Macroscopic Coupled Modeling of Batteries and Fuel and interface morphology and chemistry, has been developed for advanced batteries and fuel cells-cadmium and nickel-metal hydride batteries are carried out. The micro-macroscopic model can be used to explore

Wang, Chao-Yang

172

J. Electrochem. Soc., in press (1998) Micro-Macroscopic Coupled Modeling of Batteries and Fuel Cells  

E-print Network

1 J. Electrochem. Soc., in press (1998) Micro-Macroscopic Coupled Modeling of Batteries and Fuel taken into account. These gas reactions represent an important mechanism for battery overcharge to simulate batteries and fuel cells was described. The model is capable of incorporating interfacial non

Wang, Chao-Yang

173

J. Electrochem. Soc., in press (1998) MicroMacroscopic Coupled Modeling of Batteries and Fuel Cells  

E-print Network

1 J. Electrochem. Soc., in press (1998) Micro­Macroscopic Coupled Modeling of Batteries and Fuel taken into account. These gas reactions represent an important mechanism for battery overcharge to simulate batteries and fuel cells was described. The model is capable of incorporating interfacial non

Wang, Chao-Yang

174

A two-phase flow model for hydrogen evolution in an electrochemical cell  

Microsoft Academic Search

Hydrogen evolution, flow field and current density distribution in an electrochemical cell are investigated with a two-phase flow model. The mathematical model involves solutions of transport equations for the variables of each phase with allowance for inter-phase transfer of mass and momentum. The buoyancy force generated due to density difference between two phases modifies flow profile and increases fluid velocity

Mahmut D. Mat; Kemal Aldas; Olusegun J. Ilegbusi

2004-01-01

175

Positive Energy From rechargeable batteries to fuel cells: electrochemical energy as one  

E-print Network

between any two massive bodies (for instance the earth and sun) is called gravitational energy; the partPositive Energy From rechargeable batteries to fuel cells: electrochemical energy as one concern for the environment have brought the issue of energy production and exploitation to the public

Andelman, David

176

Free Energies of Formation Measurements on Solid-State Electrochemical Cells  

ERIC Educational Resources Information Center

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)

Rollino, J. A.; Aronson, S.

1972-01-01

177

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

DOEpatents

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.

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

2010-11-23

178

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

DOEpatents

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.

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

2010-03-02

179

Cyclo-Aliphatic Epoxide Based Photo Cured Gelled Electrolytes for Secondary Li Battery Applications. Electrochemical Kinetic Studies  

NASA Technical Reports Server (NTRS)

Cyclo aliphatic epoxide based thin gelled fils prepared by UV photo curing were characterized electrochemically. Thylene carbonate (EC) mixed with different organic liquids in different volume ratios were used as solvents.

Nagasubramanian, G.; Surampudi, S.; Halpert, G.

1993-01-01

180

Electrochemical Properties of Poly(3-alkylthiophene) Gel and Its Characteristics as an Electrode Active Material in Secondary Battery  

NASA Astrophysics Data System (ADS)

Electrochemical characteristics of an electrochemically prepared poly(3-alkylthiophene) gel and its battery characteristics have been studied. The gel film exhibited an oxidation wave in electrochemical measurements whereas the as-prepared film showed an additional peak at lower potential. Oxidation and reduction peak potentials showed marked decrease with increasing concentrations of chloroform in the electrolyte solution. These results have been explained in terms of structural disorders in the side and the main chains. Upon increasing the polymerization potential, the expansion ratio and the diffusion coefficient of dopant ion, D app, of the gel film increased. The gel film exhibited better characteristics as an electrode active material in comparison with the as-prepared film. These results of electrochemical properties of the gel film have been attributed to the effects of free volume in the gel having a three-dimensional network structure.

Shakuda, Shuzo; Kawai, Tsuyoshi; Morita, Shigenori; Yoshino, Katsumi

1994-07-01

181

Electrochemical cell for obtaining oxygen from carbon dioxide atmospheres  

NASA Technical Reports Server (NTRS)

For manned missions to Mars to become a reality, an efficient and reliable means of obtaining oxygen from the carbon dioxide-rich atmosphere will be required. Otherwise, the high cost of transporting the oxygen needed to sustain the astronauts will severely restrict the expedition to the martian surface. Recently, the use of electrochemical devices has been explored as a means of obtaining oxygen from the carbon dioxide-rich atmosphere. In these devices, oxygen ions diffuse through solid oxide membranes, thus, separating oxygen from the other gases presented. This phenomenon has only recently been explored as a means of obtaining large quantities of oxygen from toxic atmospheres, although first observed by Walter nernst in 1899. Nernst observed that stabilized zirconia will conduct oxygen ions when an electrical potential is applied across metallic electrodes applied to the ceramic membrane. Diatomic oxygen molecules are dissociated at the positive electrode/electrolyte interface. The oxygen ions enter the ceramic body due to the ion density gradient which is produced by the electrical potential across the electrolytic membrane. Once the ions have diffused through the membrane, they reform diatomic oxygen molecules at the anode. The separation of oxygen from carbon dioxide is achieved by the combination of thermal and electrochemical processes. The thermal decomposition of carbon dioxide (at 1000 C) results in the production of carbon monoxide and oxygen by the reaction.

Hooker, M. W.; Rast, H. E.; Rogers, D. K.

1989-01-01

182

Design, evaluation, and application of continuous flow cells for organic electrochemical synthesis. Progress report  

SciTech Connect

The strategy of paired electrochemical synthesis for the production of organic chemicals can result in as much as a 50% reduction in energy consumption, as compared to conventional electroorganic synthesis. A continuation of the research in paired synthesis, presently being conducted in this laboratory, is proposed. The future proposed work includes: (1) A continuing investigation into the chemistry of paired electroorganic reactions; (2) The engineering analysis and design of the electrochemical flow cell and separation equipment required for a synthesis; and (3) A bench scale pilot plant study and economic analysis of a synthesis.

Nobe, K.

1982-03-01

183

Electrochemical analysis of transparent oxide-less photovoltaic cell with perforation patterned metal substrate  

NASA Astrophysics Data System (ADS)

In terms of electrochemical behaviour, a transparent conductive oxide (TCO)-less dye-sensitized solar cell (DSSC) with two metal foils was compared with those of a metal foil-based DSSC with a TCO-coated substrate. By virtue of electrochemical impedance spectroscopy, intensity modulated photocurrent spectroscopy, intensity modulated photovoltage spectroscopy, open-circuit voltage decay, and photocurrent transient measurements, it was clearly confirmed that the limited performance of the TCO-less DSSC was caused by the restricted transport of ion species in the electrolyte due to the perforation patterned metal foil.

Kim, Myoung; You, In-Kyu; Lee, Kyoung-Won; Lee, In-Hwan; Yun, Ho-Gyeong

2013-05-01

184

Membrane with internal passages to permit fluid flow and an electrochemical cell containing the same  

NASA Technical Reports Server (NTRS)

The invention provides an improved proton exchange membrane for use in electrochemical cells having internal passages parallel to the membrane surface, an apparatus and process for making the membrane, membrane and electrode assemblies fabricated using the membrane, and the application of the membrane and electrode assemblies to a variety of devices, both electrochemical and otherwise. The passages in the membrane extend from one edge of the membrane to another and allow fluid flow through the membrane and give access directly to the membrane for purposes of hydration.

Cisar, Alan J. (Inventor); Gonzalez-Martin, Anuncia (Inventor); Hitchens, G. Duncan (Inventor); Murphy, Oliver J. (Inventor)

1997-01-01

185

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

DOEpatents

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.

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

1992-01-14

186

Characterizing Ion Profiles in Dynamic Junction Light-Emitting Electrochemical Cells  

SciTech Connect

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.

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

2013-11-27

187

Coupling of a scanning flow cell with online electrochemical mass spectrometry for screening of reaction selectivity  

NASA Astrophysics Data System (ADS)

In this work the online coupling of a miniaturized electrochemical scanning flow cell (SFC) to a mass spectrometer is introduced. The system is designed for the determination of reaction products in dependence of the applied potential and/or current regime as well as fast and automated change of the sample. The reaction products evaporate through a hydrophobic PTFE membrane into a small vacuum probe, which is positioned only 50-100 ?m away from the electrode surface. The probe is implemented into the SFC and directly connected to the mass spectrometer. This unique configuration enables fast parameter screening for complex electrochemical reactions, including investigation of operation conditions, composition of electrolyte, and material composition. The technical developments of the system are validated by initial measurements of hydrogen evolution during water electrolysis and electrochemical reduction of CO2 to various products, showcasing the high potential for systematic combinatorial screening by this approach.

Grote, Jan-Philipp; Zeradjanin, Aleksandar R.; Cherevko, Serhiy; Mayrhofer, Karl J. J.

2014-10-01

188

Electrochemical studies on niobium triselenide cathode material for lithium rechargeable cells  

NASA Technical Reports Server (NTRS)

The electrochemical behavior of NbSe3 in the battery electrolyte 1.5M LiAsF6/2Me-THF is reported. 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 NbSe3 as well as the rate governing processes in the reduction of NbSe3. An equivalent circuit has been formulated to represent the NbSe3-solution interface. The kinetic parameters for the reduction of NbSe3 were evaluated from the ac and dc measurements. The structural change in NbSe3 on lithiation during initial discharge which results in higher cell voltages and different electrochemical response as compared to virgin NbSe3 was identified to be a loss of crystallographic order.

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

1989-01-01

189

Scanning Electrochemical Cell Microscopy: A Versatile Technique for Nanoscale Electrochemistry and Functional Imaging  

NASA Astrophysics Data System (ADS)

Scanning electrochemical cell microscopy (SECCM) is a new pipette-based imaging technique purposely designed to allow simultaneous electrochemical, conductance, and topographical visualization of surfaces and interfaces. SECCM uses a tiny meniscus or droplet, at the end of a double-barreled (theta) pipette, for high-resolution functional imaging and nanoscale electrochemical measurements. Here we introduce this technique and provide an overview of its principles, instrumentation, and theory. We discuss the power of SECCM in resolving complex structure-activity problems and provide considerable new information on electrode processes by referring to key example systems, including graphene, graphite, carbon nanotubes, nanoparticles, and conducting diamond. The many longstanding questions that SECCM has been able to answer during its short existence demonstrate its potential to become a major technique in electrochemistry and interfacial science.

Ebejer, Neil; Güell, Aleix G.; Lai, Stanley C. S.; McKelvey, Kim; Snowden, Michael E.; Unwin, Patrick R.

2013-06-01

190

Electrochemical Reconstitution of Biomolecules for Applications as Electrocatalysts for the Bionanofuel Cell  

NASA Technical Reports Server (NTRS)

Platinum-cored ferritins were synthesized as electrocatalysts by electrochemical biomineralization of immobilized apoferritin with platinum. The platinum cored ferritin was fabricated by exposing the immobilized apoferritin to platinum ions at a reduction potential. On the platinum-cored ferritin, oxygen is reduced to water with four protons and four electrons generated from the anode. The ferritin acts as a nano-scale template, a biocompatible cage, and a separator between the nanoparticles. This results in a smaller catalyst loading of the electrodes for fuel cells or other electrochemical devices. In addition, the catalytic activity of the ferritin-stabilized platinum nanoparticles is enhanced by the large surface area and particle size phenomena. The work presented herein details the immobilization of ferritin with various surface modifications, the electrochemical biomineralization of ferritin with different inorganic cores, and the fabrication of self-assembled 2-D arrays with thiolated ferritin.

Kim, Jae-Woo; Choi, Sang H.; Lillehei, Peter T.; King, Glen C.; Watt, Gerald D.; Chu, Sang-Hyon; Park, Yeonjoon; Thibeault, Sheila

2004-01-01

191

Nanoarchitectured electrochemical cytosensors for selective detection of leukemia cells and quantitative evaluation of death receptor expression on cell surfaces.  

PubMed

The variable susceptibility to the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) treatment observed in various types of leukemia cells is related to the difference in the expression levels of death receptors, DR4 and DR5, on the cell surfaces. Quantifying the DR4/DR5 expression status on leukemia cell surfaces is of vital importance to the development of diagnostic tools to guide death receptor-based leukemia treatment. Taking the full advantages of novel nanobiotechnology, we have developed a robust electrochemical cytosensing approach toward ultrasensitive detection of leukemia cells with detection limit as low as ~40 cells and quantitative evaluation of DR4/DR5 expression on leukemia cell surfaces. The optimization of electron transfer and cell capture processes at specifically tailored nanobiointerfaces and the incorporation of multiple functions into rationally designed nanoprobes provide unique opportunities of integrating high specificity and signal amplification on one electrochemical cytosensor. The high sensitivity and selectivity of this electrochemical cytosensing approach also allows us to evaluate the dynamic alteration of DR4/DR5 expression on the surfaces of living cells in response to drug treatments. Using the TRAIL-resistant HL-60 cells and TRAIL-sensitive Jurkat cells as model cells, we have further verified that the TRAIL susceptibility of various types of leukemia cells is directly correlated to the surface expression levels of DR4/DR5. This versatile electrochemical cytosensing platform is believed to be of great clinical value for the early diagnosis of human leukemia and the evaluation of therapeutic effects on leukemia patients after radiation therapy or drug treatment. PMID:23621478

Zheng, Tingting; Fu, Jia-Ju; Hu, Lihui; Qiu, Fan; Hu, Minjin; Zhu, Jun-Jie; Hua, Zi-Chun; Wang, Hui

2013-06-01

192

A versatile electrochemical cell for the preparation and characterisation of model electrocatalytic systems.  

PubMed

An electrochemical cell for the controllable modification and comprehensive electrochemical characterisation of model electro-catalytic surfaces has been developed. In-depth electrochemical characterisation of stationary electrodes as well as rotating disc electrode (RDE) measurements in hanging meniscus configuration becomes possible. Additionally, the temperature of the electrodes in contact with electrolytes can be accurately controlled between room temperature and 70-80 °C. It is of particular importance for model electro-catalytic studies that in one experimental set-up (i) electrochemical metal and non-metal deposition to adjust the amount of the foreign atoms at the surface, (ii) controllable thermal treatment to vary the position of these atoms at the surface and subsurface regions, and (iii) state-of-the-art techniques common in electrocatalysis to characterise the resulting samples are possible. The deposition and annealing procedures under various atmospheres allow accurate control over the position of the foreign atoms at the electrode surface as overlayers, surface alloys and sub-surface (or near-surface) alloys, where the solute element is preferentially located in the second atomic layer of the host metal. The cell enables us to perform all operations without exposing the samples to the laboratory atmosphere at any of the experimental stages. To demonstrate the performance and advantages of the developed cell, we use model experiments with Pt(111) single crystal electrodes and Pt(111) surfaces modified with (sub)monolayer amounts of copper. PMID:23817497

Tymoczko, Jakub; Schuhmann, Wolfgang; Bandarenka, Aliaksandr S

2013-08-21

193

Method of making an electrolyte for an electrochemical cell  

DOEpatents

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.

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

1996-01-01

194

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

NASA Astrophysics Data System (ADS)

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.

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

2012-06-01

195

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

Microsoft Academic Search

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

Wallace

1983-01-01

196

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

Microsoft Academic Search

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

Wallace

1983-01-01

197

Electrochemical Gating of Tricarboxylic Acid Cycle in Electricity-Producing Bacterial Cells of Shewanella  

PubMed Central

Energy-conversion systems mediated by bacterial metabolism have recently attracted much attention, and therefore, demands for tuning of bacterial metabolism are increasing. It is widely recognized that intracellular redox atmosphere which is generally tuned by dissolved oxygen concentration or by appropriate selection of an electron acceptor for respiration is one of the important factors determining the bacterial metabolism. In general, electrochemical approaches are valuable for regulation of redox-active objects. However, the intracellular redox conditions are extremely difficult to control electrochemically because of the presence of insulative phospholipid bilayer membranes. In the present work, the limitation can be overcome by use of the bacterial genus Shewanella, which consists of species that are able to respire via cytochromes abundantly expressed in their outer-membrane with solid-state electron acceptors, including anodes. The electrochemical characterization and the gene expression analysis revealed that the activity of tricarboxylic acid (TCA) cycle in Shewanella cells can be reversibly gated simply by changing the anode potential. Importantly, our present results for Shewanella cells cultured in an electrochemical system under poised potential conditions showed the opposite relationship between the current and electron acceptor energy level, and indicate that this unique behavior originates from deactivation of the TCA cycle in the (over-)oxidative region. Our result obtained in this study is the first demonstration of the electrochemical gating of TCA cycle of living cells. And we believe that our findings will contribute to a deeper understanding of redox-dependent regulation systems in living cells, in which the intracellular redox atmosphere is a critical factor determining the regulation of various metabolic and genetic processes. PMID:23977370

Matsuda, Shoichi; Liu, Huan; Kouzuma, Atsushi; Watanabe, Kazuya; Hashimoto, Kazuhito; Nakanishi, Shuji

2013-01-01

198

Electroporation followed by electrochemical measurement of quantal transmitter release from single cells using a patterned microelectrode  

PubMed Central

An electrochemical microelectrode located immediately adjacent to a single neuroendocrine cell can record spikes of amperometric current that result from exocytosis of oxidizable transmitter from individual vesicles, i.e., quantal exocytosis. Here, we report the development of an efficient method where the same electrochemical microelectrode is used to electropermeabilize an adjacent chromaffin cell and then measure the consequent quantal catecholamine release using amperometry. Trains of voltage pulses, 5–7 V in amplitude and 0.1–0.2 ms in duration, were used to reliably trigger release from cells using gold electrodes. Amperometric spikes induced by electropermeabilization had similar areas, peak heights and durations as amperometric spikes elicited by depolarizing high K+ solutions, therefore release occurs from individual secretory granules. Uptake of trypan blue stain into cells demonstrated that the plasma membrane is permeabilized by the voltage stimulus. Voltage pulses did not degrade the electrochemical sensitivity of the electrodes assayed using a test analyte. Surprisingly, robust quantal release was elicited upon electroporation in the absence of Ca2+ in the bath solution (0 Ca2+/5 mM EGTA). In contrast, electropermeabilization-induced transmitter release required Cl? in the bath solution in that bracketed experiments demonstrated a steep dependence of the rate of electropermeabilization-induced transmitter release on [Cl?] between 2 and 32 mM. Using the same electrochemical electrode to electroporate and record quantal release of catecholamines from an individual chromaffin cell allows precise timing of the stimulus, stimulation of a single cell at a time, and can be used to load membrane-impermeant substances into a cell. PMID:23598689

Ghosh, Jaya; Liu, Xin; Gillis, Kevin D.

2013-01-01

199

Life testing of secondary silver-zinc cells  

NASA Astrophysics Data System (ADS)

Testing on a variety of secondary silver-zinc (Ag-Zn) cells has been in progress at the Marshall Space Flight Center (MSFC) for over six years. The latest test involves a 350-Ah cell design that has been cycled at 10 C for 16 months. This design has achieved over 7200 low-earth-orbit (LEO) cycles as well as 17 deep discharges at an 85 percent depth of discharge. This test not only is a life test on these cells but also addresses different methods of storing these cells between the deep discharges. As the test is approaching completion, some interesting results are being seen. In particular, two of the four packs currently on test have failed to meet the 35-h (295-Ah) deep discharge requirement that was arbitrarily set at the beginning of the test. This capacity loss failure is likely a result of the storage method used on these two packs between deep discharges. The two packs are LEO cycled in such a way as to minimize overcharge in an attempt to prolong life.

Brewer, Jeffrey C.; Doreswamy, Rajiv

200

Life testing of secondary silver-zinc cells  

NASA Technical Reports Server (NTRS)

Testing on a variety of secondary silver-zinc (Ag-Zn) cells has been in progress at the Marshall Space Flight Center (MSFC) for over six years. The latest test involves a 350-Ah cell design that has been cycled at 10 C for 16 months. This design has achieved over 7200 low-earth-orbit (LEO) cycles as well as 17 deep discharges at an 85 percent depth of discharge. This test not only is a life test on these cells but also addresses different methods of storing these cells between the deep discharges. As the test is approaching completion, some interesting results are being seen. In particular, two of the four packs currently on test have failed to meet the 35-h (295-Ah) deep discharge requirement that was arbitrarily set at the beginning of the test. This capacity loss failure is likely a result of the storage method used on these two packs between deep discharges. The two packs are LEO cycled in such a way as to minimize overcharge in an attempt to prolong life.

Brewer, Jeffrey C.; Doreswamy, Rajiv

1991-01-01

201

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

SciTech Connect

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.

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

1990-06-01

202

Electrochemical and spectroscopic studies of fuel cell reactions  

Microsoft Academic Search

Fuel cells, especially proton exchange membrane fuel cells (PEMFCs) are expected soon to become a major source of clean energy. However, the sluggish kinetics of the fuel cell reactions, i.e., the fuel oxidation and oxygen reduction, hinders the wide-spread application of PEMFCs. These problems prompted our studies to focus on elucidating the nature of the reaction intermediates during the oxidation

Minhua Shao

2006-01-01

203

Synthesis of cobalt oxide-reduced graphene nanocomposite and its enhanced electrochemical properties as negative material for alkaline secondary battery  

NASA Astrophysics Data System (ADS)

A potential negative electrode material Co3O4@rGO is synthesized via a facile reflux condensation route. The electrochemical performances of Co3O4@rGO composite for alkaline rechargeable Ni/Co batteries have been systemically investigated for the first time. The reduced-graphene can remarkably enhance the electrochemical activity of Co3O4 materials, leading to a notable improvement of discharge capacity, cycle stability and rate capability. Interestingly, the maximum discharge capacity of Co3O4@rGO-20 (additive amount of GO is 20 mg) electrode can reach 511.4 mAh g-1 with the capacity retention of 89.1% after 100 cycles at a discharge current of 100 mA g-1. A properly electrochemical reaction mechanism of Co3O4@rGO electrode is also constructed in detail.

Xu, Yanan; Wang, Xiaofeng; An, Cuihua; Wang, Yijing; Jiao, Lifang; Yuan, Huatang

2014-12-01

204

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.

2011-06-09

205

Aptamer based electrochemical sensor for detection of human lung adenocarcinoma A549 cells  

NASA Astrophysics Data System (ADS)

We report results of the studies relating to development of an aptamer-based electrochemical biosensor for detection of human lung adenocarcinoma A549 cells. The aminated 85-mer DNA aptamer probe specific for the A549 cells has been covalently immobilized onto silane self assembled monolayer (SAM) onto ITO surface using glutaraldehyde as the crosslinker. The results of cyclic voltammetry and differential pulse voltammetry studies reveal that the aptamer functionalized bioelectrode can specifically detect lung cancer cells in the concentration range of 103 to 107 cells/ml with detection limit of 103 cells/ml within 60 s. The specificity studies of the bioelectrode have been carried out with control KB cells. No significant change in response is observed for control KB cells as compared to that of the A549 target cells.

Sharma, Rachna; Varun Agrawal, Ved; Sharma, Pradeep; Varshney, R.; Sinha, R. K.; Malhotra, B. D.

2012-04-01

206

Nanocapillary electrophoretic electrochemical chip: towards analysis of biochemicals released by single cells  

PubMed Central

A novel nanocapillary electrophoretic electrochemical (Nano-CEEC) chip has been developed to demonstrate the possibility of zeptomole-level detection of neurotransmitters released from single living cells. The chip integrates three subunits to collect and concentrate scarce neurotransmitters released from single PC-12 cells, including a pair of targeting electrodes for single cells captured by controlling the surface charge density; a dual-asymmetry electrokinetic flow device for sample collection, pre-concentration and separation in a nanochannel; and an online electrochemical detector for zeptomole-level sample detection. This Nano-CEEC chip integrates a polydimethylsiloxane microchannel for cell sampling and biomolecule separation and a silicon dioxide nanochannel for sample pre-concentration and amperometric detection. The cell-capture voltage ranges from 0.1 to 1.5 V with a frequency of 1–10 kHz for PC-12 cells, and the single cell-capture efficiency is optimized by varying the duration of the applied field. All of the processes, from cell sampling to neurotransmitter detection, can be completed within 15 min. Catecholamines, including dopamine and norepinephrine (noradrenaline) released from coupled single cells, have been successfully detected using the Nano-CEEC chip. A detection limit of 30–75 zeptomoles was achieved, which is close to the levels released by a single neuron in vitro. PMID:23050079

Wu, Ren-Guei; Yang, Chung-Shi; Cheing, Ching-Chang; Tseng, Fan-Gang

2011-01-01

207

Nanocapillary electrophoretic electrochemical chip: towards analysis of biochemicals released by single cells.  

PubMed

A novel nanocapillary electrophoretic electrochemical (Nano-CEEC) chip has been developed to demonstrate the possibility of zeptomole-level detection of neurotransmitters released from single living cells. The chip integrates three subunits to collect and concentrate scarce neurotransmitters released from single PC-12 cells, including a pair of targeting electrodes for single cells captured by controlling the surface charge density; a dual-asymmetry electrokinetic flow device for sample collection, pre-concentration and separation in a nanochannel; and an online electrochemical detector for zeptomole-level sample detection. This Nano-CEEC chip integrates a polydimethylsiloxane microchannel for cell sampling and biomolecule separation and a silicon dioxide nanochannel for sample pre-concentration and amperometric detection. The cell-capture voltage ranges from 0.1 to 1.5 V with a frequency of 1-10 kHz for PC-12 cells, and the single cell-capture efficiency is optimized by varying the duration of the applied field. All of the processes, from cell sampling to neurotransmitter detection, can be completed within 15 min. Catecholamines, including dopamine and norepinephrine (noradrenaline) released from coupled single cells, have been successfully detected using the Nano-CEEC chip. A detection limit of 30-75 zeptomoles was achieved, which is close to the levels released by a single neuron in vitro. PMID:23050079

Wu, Ren-Guei; Yang, Chung-Shi; Cheing, Ching-Chang; Tseng, Fan-Gang

2011-10-01

208

Solid solution of nickel oxide and manganese oxide as negative active material for lithium secondary cells  

NASA Astrophysics Data System (ADS)

The solid solution of nickel oxide and manganese oxide has been synthesized successfully by heating Ni 1- aMn aOOH at a temperature ranging from 350 to 1000 °C in oxygen atmosphere, and investigated as a high-capacity negative active material for lithium secondary cells. The discharge capacity of nickel and manganese oxide solid solution was decreased with increasing heat-treatment temperature. The average discharge potential shifts toward negative as increasing Mn content in the solid solution. Meanwhile, large amount of Mn in the oxide solid solution caused a poor cycleability. The Ni 0.75Mn 0.25O 1.36 obtained by heating its raw material at 600 °C delivered a large discharge capacity over 700 mAh g -1 with a relatively low average discharge potential of 1.69 versus Li/Li +. In addition, the Ni 0.75Mn 0.25O 1.36 gave the best capacity retention of 91% with representative charge-discharge curves even after 22 cycles. According to the results of XRD and high-resolution X-ray fluorescence spectrometer (HRXRF) measurements for the oxide solid solution before and after the first charge, it was clear that an amorphous-like or nano-sized phase was formed during the first electrochemical reduction; all of the nickel and a part of manganese were reduced to metallic state after charge to 0.2 V versus Li/Li +.

Liu, Xingjiang; Yasuda, Hideo; Yamachi, Masanori

209

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

PubMed Central

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

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

2011-01-01

210

Note: A quartz cell with Pt single crystal bead electrode for electrochemical scanning tunneling microscope measurements.  

PubMed

In this paper, we provide and demonstrate a design of a unique cell with Pt single crystal bead electrode for electrochemical scanning tunneling microscope (ECSTM) measurements. The active metal Pt electrode can be protected from air contamination during the preparation process. The transparency of the cell allows the tip and bead to be aligned by direct observation. Based on this, a new and effective alignment method is introduced. The high-quality bead preparations through this new cell have been confirmed by the ECSTM images of Pt (111). PMID:25273789

Xia, Zhigang; Wang, Jihao; Hou, Yubin; Lu, Qingyou

2014-09-01

211

Electrochemical cell for neutron reflectometry studies of the structure of ionic liquids at electrified interface  

NASA Astrophysics Data System (ADS)

We describe the design and use of a closed three-electrode electrochemical cell for neutron reflectometry studies of the structure of the electrical double-layer in ionic liquids. A transparent glass counter electrode was incorporated to allow easy monitoring of any gas bubbles trapped in the cell. A 100 mm diameter silicon wafer polished to 0.1 nm rms roughness coated with gold over a chromium adhesion layer was used as the working electrode. The utility of the cell was demonstrated during neutron reflectometry measurements of the ultrahigh purity ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C4mpyr][NTf2]) at two different applied potentials.

Lauw, Y.; Rodopoulos, T.; Gross, M.; Nelson, A.; Gardner, R.; Horne, M. D.

2010-07-01

212

The electrochemical performance of thin-electrolyte solid oxide fuel cells  

NASA Astrophysics Data System (ADS)

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.

Zurawski, D.; Kueper, T.

1993-04-01

213

Note: A quartz cell with Pt single crystal bead electrode for electrochemical scanning tunneling microscope measurements  

NASA Astrophysics Data System (ADS)

In this paper, we provide and demonstrate a design of a unique cell with Pt single crystal bead electrode for electrochemical scanning tunneling microscope (ECSTM) measurements. The active metal Pt electrode can be protected from air contamination during the preparation process. The transparency of the cell allows the tip and bead to be aligned by direct observation. Based on this, a new and effective alignment method is introduced. The high-quality bead preparations through this new cell have been confirmed by the ECSTM images of Pt (111).

Xia, Zhigang; Wang, Jihao; Hou, Yubin; Lu, Qingyou

2014-09-01

214

Characterization of PEM fuel cell membrane-electrode-assemblies by electrochemical methods and microanalysis  

SciTech Connect

Characterization of Membrane Electrode Assemblies (MEAs) is used to help optimize construction of the MEA. Characterization techniques include electron microscopies (SEM and TEM), and electrochemical evaluation of the catalyst. Electrochemical hydrogen adsorption/desorption (HAD) and CO oxidation are used to evaluate the active Pt surface area of fuel cell membrane electrode assemblies. Electrochemical surface area measurements have observed large active Pt surface areas, on the order of 50 m{sup 2}/g for 20% weight Pt supported on graphite. Comparison of the hydrogen adsorption/desorption with CO oxidation indicates that on the supported catalysts, the saturation coverage of CO/Pt is about 0.90, the same as observed in H{sub 2}SO{sub 4}. The catalyst surface area measurements are nearly a factor of 2 lower than the Pt surface area calculated from the 30 {angstrom} average particle size observed by TEM. The electrochemical measurements combined with microanalysis of membrane electrode assemblies, allow a greater understanding and optimization of process variables.

Borup, R.L.; Vanderborgh, N.E.

1995-09-01

215

Electrochemical biosensors for on-chip detection of oxidative stress from immune cells  

PubMed Central

Seamless integration of biological components with electrochemical sensors is critical in the development of microdevices for cell analysis. The present paper describes the integration miniature Au electrodes next to immune cells (macrophages) in order to detect cell-secreted hydrogen peroxide (H2O2). Photopatterning of poly(ethylene glycol) (PEG) hydrogels was used to both immobilize horseradish peroxidase molecules onto electrodes and to define regions for cell attachment in the vicinity of sensing electrodes. Electrodes micropatterned in such a manner were enclosed inside poly(dimethylsiloxane) fluid conduits and incubated with macrophages. The cells attached onto the exposed glass regions in the vicinity of the electrodes and nowhere else on the non-fouling PEG hydrogel surface. A microfluidic device was converted into an electrochemical cell by placing flow-through Ag?AgCl reference and Pt wire counter electrodes at the outlet and inlet, respectively. This microdevice with integrated H2O2-sensing electrodes had sensitivity of 27 ?A?cm2 mM with a limit of detection of 2 ?M. Importantly, this microdevice allowed controllable seeding of macrophages next to electrodes, activation of these cells and on-chip monitoring of H2O2 release in real time. In the future, this biosensor platform may be utilized for monitoring of macrophage responses to pathogens or for the study of inflammatory signaling in micropatterned cell cultures. PMID:22007269

Yan, Jun; Pedrosa, Valber A.; Enomoto, James; Simonian, Aleksandr L.; Revzin, Alexander

2011-01-01

216

Potassium Beta-Alumina/Molybdenum/Potassium Electrochemical Cells  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

217

Electrochemical evaluation of molybdenum disulfide as a catalyst for hydrogen evolution in microbial electrolysis cells  

Microsoft Academic Search

There is great interest in hydrogen evolution in bioelectrochemical systems, such as microbial electrolysis cells (MECs), but these systems require non-optimal near-neutral pH conditions and the use of low-cost, non-precious metal catalysts. Here we show that molybdenum disulfide (MoS2) composite cathodes have electrochemical performance superior to stainless steel (SS) (currently the most promising low-cost, non-precious metal MEC catalyst) or Pt-based

Justin C. Tokash; Bruce E. Logan

2011-01-01

218

Novel duplex vapor-electrochemical method for silicon solar cells  

NASA Technical Reports Server (NTRS)

A process was developed for the economic production of high purity Si from inexpensive reactants, based on the Na reduction of SiF4 gas. The products of reaction (NaF, Si) are separated by either aqueous leaching or by direct melting of the NaF-Si product mixture. Impurities known to degrade solar cell performance are all present at sufficiently low concentrations so that melt solidification (e.g., Czochralski) will provide a silicon material suitable for solar cells.

Nanis, L.; Sanjurjo, A.; Sancier, K. M.; Kapur, V. K.; Bartlett, R. W.; Westphal, S.

1980-01-01

219

Parenchyma cell respiration and survival in secondary xylem: does metabolic activity decline with cell age?  

E-print Network

that there is no inherent or intrinsic decline in respiration as a result of cellular ageing. In contrast, it is not known whether differences observed in cellular respiration rates of angiosperms are a function of age per seParenchyma cell respiration and survival in secondary xylem: does metabolic activity decline

Holbrook, N. Michele

220

Low-hazard metallography of moisture-sensitive electrochemical cells.  

PubMed

A low-hazard approach is presented to prepare metallographic cross-sections of moisture-sensitive battery components. The approach is tailored for evaluation of thermal (molten salt) batteries composed of thin pressed-powder pellets, but has general applicability to other battery electrochemistries. Solution-cast polystyrene is used to encapsulate cells before embedding in epoxy. Nonaqueous grinding and polishing are performed in an industrial dry room to increase throughput. Lapping oil is used as a lubricant throughout grinding. Hexane is used as the solvent throughout processing; occupational exposure levels are well below the limits. Light optical and scanning electron microscopy on cross-sections are used to analyse a thermal battery cell. Spatially resolved X-ray diffraction on oblique angle cut cells complement the metallographic analysis. PMID:21477264

Wesolowski, D E; Rodriguez, M A; McKenzie, B B; Papenguth, H W

2011-08-01

221

Process for manufacturing a lithium alloy electrochemical cell  

DOEpatents

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.

Bennett, William R. (North Olmstead, OH)

1992-10-13

222

Assessment of multidrug resistance on cell coculture patterns using scanning electrochemical microscopy  

PubMed Central

The emergence of resistance to multiple unrelated chemotherapeutic drugs impedes the treatment of several cancers. Although the involvement of ATP-binding cassette transporters has long been known, there is no in situ method capable of tracking this transporter-related resistance at the single-cell level without interfering with the cell’s environment or metabolism. Here, we demonstrate that scanning electrochemical microscopy (SECM) can quantitatively and noninvasively track multidrug resistance-related protein 1–dependent multidrug resistance in patterned adenocarcinoma cervical cancer cells. Nonresistant human cancer cells and their multidrug resistant variants are arranged in a side-by-side format using a stencil-based patterning scheme, allowing for precise positioning of target cells underneath the SECM sensor. SECM measurements of the patterned cells, performed with ferrocenemethanol and [Ru(NH3)6]3+ serving as electrochemical indicators, are used to establish a kinetic “map” of constant-height SECM scans, free of topography contributions. The concept underlying the work described herein may help evaluate the effectiveness of treatment administration strategies targeting reduced drug efflux. PMID:23686580

Kuss, Sabine; Polcari, David; Geissler, Matthias; Brassard, Daniel; Mauzeroll, Janine

2013-01-01

223

Highly sensitive and selective detection of cancer cell with a label-free electrochemical cytosensor.  

PubMed

Electrochemical methods have attracted considerable attention for developing cytosensing system since they can decrease the cost and time requirement for cell detection with simple instrumentation. Herein, a label-free electrochemical cytosensor with surface-confined ferrocene as signal indicator was developed for highly sensitive and selective detection of cancer cell. With layer-by-layer (LBL) self-assembly technique, positively charged poly(ethylene imine) functionalized with ferrocene (Fc-PEI) and negatively charged single-wall carbon nanotubes (SWNTs) were alternately assembled on 3-mercaptopropionic acid (MPA) modified gold substrate. Folic acid (FA) was covalently bonded onto SWNTs surface to specifically recognize cancer cells according to the high affinity of FA for folate receptor (FR) on cellular surface. The developed cytosensor presented high sensitivity and selectivity for the detection of human cervical carcinoma (HeLa) cell. By using fast-response differential pulse voltammetry (DPV) method, a wide detection range from 10 to 10(6) cells/mL with a detection limit as low as 10 cells/mL was reached even in the presence of a large amount of non-cancerous cells. PMID:23036771

Liu, Jiyang; Qin, Yinan; Li, Dan; Wang, Tianshu; Liu, Yaqing; Wang, Jin; Wang, Erkang

2013-03-15

224

Influence of compressible aerogel electrodes on the properties of an electrochemical cell  

NASA Astrophysics Data System (ADS)

In the biomedical field the need for intra organ pressure measurement can only be facilitated by adapting existing pressure sensing technology to the specific tissues under test. The customization of these sensors has only driven up cost and the need to explore new technologies has become increasingly more important. For this dissertation, we explore the use of a new technology, particularly electrochemical pressure sensing to provide a low-cost pressure sensor to fill this need. Preliminary testing showed that electrically conductive polymers exhibited a change in voltage when pressurized if bubbles were first electrolyzed in the gel creating an aerogel, and that this effect was virtually undetectable without the bubbles present. Using electrochemical impedance spectroscopy (EIS) and model fitting, it was shown that this effect occurs at the electrode interface. Theoretical derivation supported by potentiostatic voltage measurements indicated that a change in the electrode surface area in contact with the fluid was responsible for the effect. Optical micrographs were taken as a bubble along the electrode was pressurized. Using image analysis, the relationship of the change in surface area of the bubble correlated to the relationship of the change in impedance of the electrochemical cell (ECC). The results further demonstrated that the electrochemical response to pressure of a gelatin aerogel electrode was linear for the pressure range of 0 to1034 mmHg. This finding lends itself well for use in medical devices. A new device was invented along with a manufacturing process for an electrochemical pressure transducer (EPT). The EPT was subject to in vitro testing using simulated gastric fluid to create a baseline efficacy of the device for use in the gastrointestinal tract. Multiple design specific techniques were developed to improve sensor performance during physiological conditions.

Sponheimer, Christopher

225

Materials development and electrochemical characterization of polymer electrolyte fuel cells  

Microsoft Academic Search

In this thesis, the materials development and mechanism characterizations of polymer electrolyte fuel cells (PEFCs) are addressed. This work starts with a new preparation technique for a modified electrode structure containing two carbon support materials. The resulted catalyzed electrode, which exhibits good materials properties, demonstrates an improved kinetics in the oxygen reduction reaction (ORR). A new electrocatalyst synthesis procedure utilizing

Xin Wang

2002-01-01

226

Life capability of the silver electrode in alkaline electrochemical cells  

NASA Technical Reports Server (NTRS)

Estimates of silver electrode degradation rates were made by comparing the recently measured capacities with the reported early life capacities. Chemical analyses were carried out to determine the extent of silver loss from the electrode and its distribution throughout the cell components. The results established that the silver electrode is very stable when stored at reduced temperatures in the range of 0 to -51 C, in which it exhibits a permanent degradation in capacity of 0.5%/year. The results also indicated that the silver electrode is not quite as stable when operated and stored at room temperature, where it exhibits permanent degradation in the range of 3% to 14%/year. These results were employed in predicting the life capability of the proposed new Ag-H2 cell and also in assessing the merits of employing silver electrodes in long-life probe batteries.

Frank, H. A.

1976-01-01

227

Direct In Vivo Electrochemical Detection of Haemoglobin in Red Blood Cells  

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

228

Direct in vivo electrochemical detection of haemoglobin in red blood cells.  

PubMed

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. PMID:25163492

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

2014-01-01

229

Graphene oxide/poly-L-lysine assembled layer for adhesion and electrochemical impedance detection of leukemia K562 cancer cells.  

PubMed

A novel biocompatible film assembled by combining of graphene oxide (GO) and poly-L-lysine (PLL) for adhesion and electrochemical impedance detection of leukemia K562 cells was proposed. The biocompatible film showed an improved immobilization capacity for living cells and a good biocompatibility for preserving the activity of the immobilized living cells. The immobilized K562 cells on the biocompatible film-modified electrode can be directly monitored with electrochemical impedance spectroscopy in the presence of [Fe(CN)?]³?/?? as redox probes. A highly sensitive electrochemical impedance method for the detection of leukemia K562 cancer cells was developed. Under the optimized conditions, the increased electron-transfer resistance with a good correlation to the logarithmic value of concentration of K562 cells ranging from 10² to 10? cells mL?¹, and with the detection limit of 30 cells mL?¹ (S/N=3). Additionally, the proposed method was used to describe the viability of cells and to evaluate the effectiveness of antitumor drug Nilotinib on K562 cells. The obtained results of Nilotinib cytotoxicity are well agreed with those from WST-1 assays. Furthermore, the work demonstrates that a highly biocompatible film of PLL/GO assembled is also expected to be an appropriate matrix for the electrochemical investigation of adhesion, proliferation, apoptosis of other relevant mammalian cells which is not limited to adherent cells, and the study of cell-based biosensors. PMID:23202339

Zhang, Dongdong; Zhang, Yanmin; Zheng, Lei; Zhan, Yingzhuan; He, Langchong

2013-04-15

230

Direct electrochemical detection of PB1-F2 protein of influenza A virus in infected cells.  

PubMed

Influenza virus represents a major concern of human health and animal production. PB1-F2 is a small proapoptotic protein supposed to contribute to the virulence of influenza A virus (IAV). However, the molecular mechanism of action of PB1-F2 is still unclear.PB1-F2 expression and behavior during the viral cycle is difficult to follow with classical biochemical methods. In this work we have developed an electrochemical biosensor based on immuno-detection system for quantification of PB1-F2 protein in infected cell. The electrochemical immunosensor was based on conducting copolypyrrole integrating ferrocenyl group as redox marker for enhancing signal detection. A specific anti-PB1-F2 monoclonal antibody was immobilized on the copolypyrrole layer via biotin-streptavidin system. We demonstrate that this electrochemical system sensitively detect purified recombinant PB1-F2 over a wide range of concentrations from 5 nM to 1.5 µM. The high sensor sensitivity allowed the detection of PB1-F2 in lysates of infected cells confirming that PB1-F2 is expressed in early stages of viral cycle. The immunosensor developed shows enhanced performances for the evaluation of PB1-F2 protein concentration in biological samples and could be applied for studying of PB1-F2 during influenza virus infection. PMID:24686222

Miodek, Anna; Sauriat-Dorizon, Helene; Chevalier, Christophe; Delmas, Bernard; Vidic, Jasmina; Korri-Youssoufi, Hafsa

2014-09-15

231

Electrochemical studies on niobium triselenide cathode material for lithium rechargeable cells  

SciTech Connect

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.

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

1989-01-01

232

Method of making electrodes for electrochemical cell. [Li-Al alloy  

DOEpatents

A method is described for making an electrode for an electrochemical cell in which particulate electrode-active material is mixed with a liquid organic carrier chemically inert with respect to the electrode-active material, mixing the liquid carrier to form an extrudable slurry. The liquid carrier is present in an amount of from about 10 to about 50% by volume of the slurry, and then the carrier is removed from the slurry leaving the electrode-active material. The method is particularly suited for making a lithium-aluminum alloy negative electrode for a high-temperature cell.

Kaun, T.D.; Kilsdonk, D.J.

1981-07-29

233

A cell for x-ray absorption studies of the emersed electrochemical interphase  

NASA Astrophysics Data System (ADS)

A cell has been constructed which allows the electrochemical interphase on electrode surfaces to be studied ex situ using glancing angle x-ray and gas phase electron yield detection. The various components of the cell are described. The electrode and interphase are emersed using the thin strip emersion technique, and the x-ray beam is totally reflected from the vertical electrode surface above the horizontal electrolyte thin strip. Examples of Au L3 edge and XAFS spectra of an anodically oxidized gold electrode at ?=4 mrad show the technique to be very surface sensitive.

Hansen, Galen J.; O'Grady, William E.

1990-08-01

234

X-ray absorption and electrochemical studies of direct methanol fuel cell catalysts  

SciTech Connect

In order for polymer electrolyte fuel cells to operate directly on methanol instead of hydrogen, methanol oxidation must be catalyzed in the acidic cell environment. Pt-Ru and Pt-Ru oxide are considered to be the most active catalysts for this purpose; Ru enhances the Pt activity for reasons not yet fully understood. XAS and electrochemical techniques were used to study this enhancement. Preliminary results indicate that Ru does effect the d-band occupancy of Pt, which in turn may effect the kinetics of the methanol oxidation reaction on this metal by altering the strength of the Pt-CO bond. Further research is needed.

Zurawski, D.J.; Aldykiewicz, A.J. Jr.; Baxter, S.F.; Krumpelt, M.

1996-12-31

235

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

DOEpatents

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.

Shockling, L.A.

1991-09-10

236

Electrochemically grown ZnO nanorods for hybrid solar cell applications  

SciTech Connect

A hybrid solar cell is designed and proposed as a feasible and reasonable alternative, according to acquired efficiency with the employment of zinc oxide (ZnO) nanorods and ZnO thin films at the same time. Both of these ZnO structures were grown electrochemically and poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester; (P3HT:PCBM) was used as an active polymer blend, which was found to be compatible to prepared indium-tin-oxide (ITO) substrate base. This ITO base was introduced with mentioned ZnO structure in such a way that, the most efficient configuration was optimized to be ITO/ZnO film/ZnO nanorod/P3HT: PCBM/Ag. Efficiency of this optimized device is found to be 2.44%. All ZnO works were carried out electrochemically, that is indeed for the first time and at relatively lower temperatures. (author)

Hames, Yakup [Department of Electrical-Electronics Engineering, Mustafa Kemal University, 31040 Hatay (Turkey); Alpaslan, Zuehal; Koesemen, Arif; San, Sait Eren; Yerli, Yusuf [Department of Physics, Gebze Institute of Technology, 41400 Gebze (Turkey)

2010-03-15

237

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

PubMed

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

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

2013-09-21

238

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

DOEpatents

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.

Shockling, Larry A. (Plum Borough, PA)

1991-01-01

239

Teaching Cell Division to Secondary School Students: An Investigation of Difficulties Experienced by Turkish Teachers  

ERIC Educational Resources Information Center

This study examines the difficulties biology teachers face when teaching cell division in the secondary schools of the central part of the Erzurum province in Turkey. During this research, a questionnaire was distributed to a total of 36 secondary school biology teachers. Findings of the study indicate biology teachers perceive cell division as…

Oztap, Haydar; Ozay, Esra; Oztap, Fulya

2003-01-01

240

BMP7 Expression Correlates with Secondary Drug Resistance in Mantle Cell Lymphoma  

E-print Network

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: We obtained paired tissue samples collected from the same patients before treatment and after relapse

Boyer, Edmond

241

Electrochemical storage  

NASA Technical Reports Server (NTRS)

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.

Thaller, L. H.

1984-01-01

242

Aptamer-aided target capturing with biocatalytic metal deposition: an electrochemical platform for sensitive detection of cancer cells.  

PubMed

A novel aptamer biosensor for cancer cell assay has been reported on the basis of ultrasensitive electrochemical detection. Cancer cell capturing is first accomplished via aptamer-aided recognition, and the cell-aptamer binding events then mediate an alkaline phosphatase-catalyzed silver deposition reaction which can be probed by electrochemical detection. Following biocatalytic silver deposition, an efficient amplification approach for sensitive electrochemical measurements is demonstrated, for cell detection with high sensitivity. Ramos cell are used as a model case, a typical biomarker of the acute blood cell cancer, Burkitt's lymphoma. The results reveal that the developed technique displays desirable selectivity in Ramos cell discrimination, and linear response range from 10 to 10(6) cells with a detection limit as low as 10 cells. Due to the simple procedures, label-free and electrochemistry based detection format, this technique is simple and cost-effective, and exhibits excellent compatibility with miniaturization technologies. The electrochemical cell detection strategy may create an intrinsically specific and sensitive platform for cancer cell assay and associated studies. PMID:23420020

Yi, Zi; Li, Xiao-Yan; Gao, Qing; Tang, Li-Juan; Chu, Xia

2013-04-01

243

The cell wall and secretory proteome of a tobacco cell line synthesising secondary wall.  

PubMed

The utility of plant secondary cell wall biomass for industrial and biofuel purposes depends upon improving cellulose amount, availability and extractability. The possibility of engineering such biomass requires much more knowledge of the genes and proteins involved in the synthesis, modification and assembly of cellulose, lignin and xylans. Proteomic data are essential to aid gene annotation and understanding of polymer biosynthesis. Comparative proteomes were determined for secondary walls of stem xylem and transgenic xylogenic cells of tobacco and detected peroxidase, cellulase, chitinase, pectinesterase and a number of defence/cell death related proteins, but not marker proteins of primary walls such as xyloglucan endotransglycosidase and expansins. Only the corresponding detergent soluble proteome of secretory microsomes from the xylogenic cultured cells, subjected to ion-exchange chromatography, could be determined accurately since, xylem-specific membrane yields were of poor quality from stem tissue. Among the 109 proteins analysed, many of the protein markers of the ER such as BiP, HSP70, calreticulin and calnexin were identified, together with some of the biosynthetic enzymes and associated polypeptides involved in polymer synthesis. However 53% of these endomembrane proteins failed identification despite the use of two different MS methods, leaving considerable possibilities for future identification of novel proteins involved in secondary wall polymer synthesis once full genomic data are available. PMID:19402043

Millar, David J; Whitelegge, Julian P; Bindschedler, Laurence V; Rayon, Catherine; Boudet, Alain-Michel; Rossignol, Michel; Borderies, Gisèle; Bolwell, G Paul

2009-05-01

244

Electrochemical Performance and Microbial Characterization of Thermophilic Microbial Fuel Cells  

NASA Astrophysics Data System (ADS)

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.

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

2007-12-01

245

The influence of the graphitic structure on the electrochemical characteristics for the anode of secondary lithium batteries  

SciTech Connect

Carbon is one of the best candidate materials for the negative electrode of rechargeable lithium batteries; however, the electrochemical characteristics are not fully understood in terms of the structure of the materials. The relationship linking the volume ration of the graphitic structure (P{sub 1}) of mesocarbon microbeads (MCMBS) and the electrochemical characteristics has been examined, and it was found that the capacity in the range between 0 to 0.25 V (vs. Li/Li{sup +}) in 1 mol/dm{sup 3} LiClO{sub 4}/ethylene carbonate (EC) + 1,2-diethoxyethane (DEE) electrolyte increased with an increase of the P{sub 1} of the MCMBs. This result shows that the lithium storage mechanism in this potential range is the lithium-intercalation reaction into the graphitic layers with the AB or ABC stacking. On the other hand, MCMB heat-treatment temperature (HTT) 1,000 C showed much larger capacity in the range between 0.25 to 1.3 V than higher HTT MCMBs, and it is suggested the interaction among each graphite layer is weaker in nongraphitized carbon than that in well-graphitized ones.

Tatsumi, K.; Iwashita, N.; Sakaebe, H.; Shioyama, H.; Higuchi, S. [Osaka National Research Inst. (Japan); Mabuchi, A.; Fujimoto, H. [Osaka Gas Co., Ltd. (Japan). Research and Development Center

1995-03-01

246

Bipolar stacked quasi-all-solid-state lithium secondary batteries with output cell potentials of over 6 V.  

PubMed

Designing a lithium ion battery (LIB) with a three-dimensional device structure is crucial for increasing the practical energy storage density by avoiding unnecessary supporting parts of the cell modules. Here, we describe the superior secondary battery performance of the bulk all-solid-state LIB cell and a multilayered stacked bipolar cell with doubled cell potential of 6.5?V, for the first time. The bipolar-type solid LIB cell runs its charge/discharge cycle over 200 times in a range of 0.1-1.0 C with negligible capacity decrease despite their doubled output cell potentials. This extremely high performance of the bipolar cell is a result of the superior battery performance of the single cell; the bulk all-solid-state cell has a charge/discharge cycle capability of over 1500 although metallic lithium and LiFePO? are employed as anodes and cathodes, respectively. The use of a quasi-solid electrolyte consisting of ionic liquid and Al?O? nanoparticles is considered to be responsible for the high ionic conductivity and electrochemical stability at the interface between the electrodes and the electrolyte. This paper presents the effective applications of SiO?, Al?O?, and CeO? nanoparticles and various Li(+) conducting ionic liquids for the quasi-solid electrolytes and reports the best ever known cycle performances. Moreover, the results of this study show that the bipolar stacked three-dimensional device structure would be a smart choice for future LIBs with higher cell energy density and output potential. In addition, our report presents the advantages of adopting a three-dimensional cell design based on the solid-state electrolytes, which is of particular interest in energy-device engineering for mobile applications. PMID:25124398

Matsuo, Takahiro; Gambe, Yoshiyuki; Sun, Yan; Honma, Itaru

2014-01-01

247

The Development of Microfabricated Microbial Fuel Cell Array as a High Throughput Screening Platform for Electrochemically Active Microbes  

E-print Network

THE DEVELOPMENT OF MICROFABRICATED MICROBIAL FUEL CELL ARRAY AS A HIGH THROUGHPUT SCREENING PLATFORM FOR ELECTROCHEMICALLY ACTIVE MICROBES A Dissertation by HUIJIE HOU Submitted to the office of graduate studies of Texas A... SCREENING PLATFORM FOR ELECTROCHEMICALLY ACTIVE MICROBES A Dissertation by HUIJIE HOU Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY...

Hou, Huijie

2012-02-14

248

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

SciTech Connect

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.

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

2011-11-01

249

Lithium Ion Secondary Cell Prepared by a Printing Procedure, and Its Application to All-Solid-State Inorganic Lithium Ion Cells  

NASA Astrophysics Data System (ADS)

We have developed a straightforward printing method for preparation of a lithium secondary cell. LiCo1/3Ni1/3Mn1/3O2 and Li4Ti5O12 viscous printable pastes were used for the cathode and anode, respectively. Electrochemical measurement was used to characterize the capacitance of each cell, and field-emission scanning electron microscopy and particle size measurements were used to characterize particle size and morphology. These film electrodes functioned stably both in a standard liquid electrolyte and in an Li2SiO3 solid electrolyte, although the capacitance of the all-solid-state cell was significantly lower than that of the cell containing liquid electrolyte. When liquid electrolyte was used, the capacity decreased by 36% after 50 cycles. However, the capacity of 0.2 mA h/g remained almost the same even after 50 charge-discharge cycles, demonstrating the stability and strength of the all-solid-state lithium ion cell. It was also found that the cell resistance mostly arose from the electrode/electrolyte interface and not from the bulk electrolyte. Addition of a sol-gel to the solid electrolyte printable paste improved cell performance.

Mori, Ryohei

2014-04-01

250

A dual-electrochemical cell to study the biocorrosion of stainless steel.  

PubMed

The presence of microorganisms on metal surfaces can alter the local physical/chemical conditions and lead to microbiologically influenced corrosion (MIC). The goal of the present work was to study the effect of a mixed aerobic-anaerobic biofilm on the behaviour of stainless steel (316 L) in underground conditions. Rather than testing different bacteria or consortia, investigations were based on the mechanisms of MIC. Mixed biofilms were simulated by the addition of glucose oxidase to reproduce the aerobic conditions and by sulphide or sulphate-reducing bacteria (SRB) for the anaerobic conditions. A double thermostated electrochemical cell has been developed to study the coupling between aerobic and anaerobic conditions. Results suggested a transfer of electrons from the stainless steel sample of the anaerobic cell to the stainless steel sample of the aerobic one. Inorganic sulphide was replaced by SRB in the anaerobic cell revealing an increase of the galvanic current which may be explained by an effect of lactate and/or acetate on the anodic reaction or by a high sulphide concentration in the biofilm. The results of this study underline that the dual-electrochemical cell system is representative of phenomena present in natural environments and should be considered as an option when studying MIC. PMID:17547022

Lopes, F A; Perrin, S; Féron, D

2007-01-01

251

The immunosuppressive effect of embryonic stem cells and mesenchymal stem cells on both primary and secondary alloimmune responses  

Microsoft Academic Search

Recently, both embryonic stem cells and mesenchymal stem cells have been demonstrated to have immunosuppressive effects. The purpose of this study was to elucidate whether the embryonic stem cells and\\/or mesenchymal stem cells modulate both primary and secondary alloimmune responses. Both stem cells suppressed in vitro proliferation and cytokine production in primary alloimmune responses. They also suppressed in vitro proliferation

Kyu Hyun Han; Hee Gyung Kang; Hae Jin Gil; Eun Mi Lee; Curie Ahn; Jaeseok Yang

2010-01-01

252

Limbal stem cell failure secondary to advanced conjunctival squamous cell carcinoma: a clinicopathological case report  

PubMed Central

A 67-year-old man with a history of multiple myeloma (treated with chemotherapy) was referred with a left hyperaemic conjunctival lesion covering almost 360° of the limbus and extending onto the corneal surface. Conjunctival biopsy revealed conjunctival intraepithelial neoplasia. Initial treatment consisted of topical and intralesional injections of interferon ?-2b. The patient subsequently developed limbal stem cell deficiency resulting in a persistent non-healing corneal epithelial defect. This was successfully managed with total excisional biopsy of the lesion, combined with limbal stem cell autograft (from the fellow eye) and amniotic membrane transplantation. Histopathology revealed a conjunctival squamous cell carcinoma. The corneal epithelium completely healed postoperatively and there is no evidence of tumour recurrence at 1 year follow-up. This case highlights a rare case of advanced ocular surface neoplasia causing secondary limbal stem cell deficiency. Medical and surgical management of ocular surface neoplasia with limbal stem cell transplantation is effective in treating such cases. PMID:22121391

Lyall, Douglas A M; Srinivasan, Sathish; Roberts, Fiona

2009-01-01

253

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

DOEpatents

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).

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

1991-01-01

254

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

PubMed

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

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

2012-11-20

255

Ultrasensitive electrochemical immunoassay for squamous cell carcinoma antigen using dumbbell-like Pt-Fe?O? nanoparticles as signal amplification.  

PubMed

Dumbbell-like Pt-Fe?O? nanoparticles (NPs) were synthesized and used as a novel kind of label for the preparation of electrochemical immunosensor, which is applied to the detection of cancer biomarker squamous cell carcinoma antigen (SCC-Ag). The signal amplification strategy, using the synergetic effect present in Pt-Fe?O? to increase the reduction ability of the NPs toward H?O?, improved the sensitivity of the immunosensor. Nitrogen-doped graphene sheets (N-GS) were synthesized from graphite oxides through thermal annealing of graphite oxides in ammonia, which was used to immobilize primary anti-SCC antibody (Ab?). Secondary anti-SCC antibody (Ab?) was adsorbed onto the Pt-Fe?O? NPs. The immunosensor was prepared through a sandwich structure and displayed a wide linear range (0.05-18 ng/mL), low detection limit (15.3 pg/mL), good reproducibility and stability. The method has been applied to the analysis of clinical serum samples with satisfactory results. These labels for immunosensors can provide many potential applications for the detection of different biomolecules. PMID:23517823

Wu, Dan; Fan, Haixia; Li, Yuyang; Zhang, Yong; Liang, Huixin; Wei, Qin

2013-08-15

256

The Lead-Lead Oxide Secondary Cell as a Teaching Resource  

ERIC Educational Resources Information Center

The assembly and use of a laboratory version of a secondary cell based on the lead-lead oxide system is described. The cell is easy to construct, sufficiently robust for student use, and has a conveniently low practical capacity of about 5 mA h. This modest cell capacity allows cell assembly, electrode formation and discharge characterization…

Smith, Michael J.; Fonseca, Antonio M.; Silva, M. Manuela

2009-01-01

257

Computer modeling of electrochemical growth with convection and migration in a rectangular cell  

NASA Astrophysics Data System (ADS)

We model the growth of electrodeposits with diffusion, convection, and migration in an electric field in a rectangular cell. From differential equations, we derive the expressions of growth probability, which predict that the direction and speed of convection and the electric field govern the pattern formation of electrochemical growth. These theoretical predictions are demonstrated by computer simulations. Different patterns, diffusion-limited aggregation, dendritic, dense, needle, and treelike, are governed by two parameters: the convection velocity in the direction parallel to the electrodes, and the flow (convection plus migration in an electric field) perpendicular to the electrodes.

Huang, Weiguang; Hibbert, D. Brynn

1996-01-01

258

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

DOEpatents

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.

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

2000-03-07

259

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

NASA Astrophysics Data System (ADS)

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.

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

2007-11-01

260

Electrochemical impedance spectroscopy to study physiological changes affecting the red blood cell after invasion by malaria parasites  

Microsoft Academic Search

The malaria parasite, Plasmodium falciparum, invades human erythrocytes and induces dramatic changes in the host cell. The idea of this work was to use RBC modified electrode to perform electrochemical impedance spectroscopy (EIS) with the aim of monitoring physiological changes affecting the erythrocyte after invasion by the malaria parasite. Impedance cell-based devices are potentially useful to give insight into cellular

Clotilde Ribaut; Karine Reybier; Olivier Reynes; Jérôme Launay; Alexis Valentin; Paul Louis Fabre; Françoise Nepveu

2009-01-01

261

Multi-gas transportation and electrochemical performance of a polymer electrolyte fuel cell with complex flow channels  

E-print Network

brass bipolar plates etched with a number of winding gas channels with a flow area of 250 mm Ã? 250 mm. The influence of anode gas humidity on the performance of the fuel cell is investigated through model predictionMulti-gas transportation and electrochemical performance of a polymer electrolyte fuel cell

262

Nanocrystalline indium tin oxide fabricated via sol-gel combustion for electrochemical luminescence cells.  

PubMed

Nanoporous indium tin oxide (ITO) was synthesized via a sol-gel combustion hybrid method using Ketjenblack as a fuel. The effects of the sol-gel combustion conditions on the structures and morphology of the ITO particles were studied. The size of the nanoporous powder was found to be 20-30 nm in diameter. The layer of the nanoporous ITO electrode (-10 microm thickness) with large surface area (-360 m2/g) was fabricated for an electrochemical luminescence (ECL) cell. At 4 V bias, the ECL efficiency of the cell consisting of the nanoporous ITO layer was approximately 1050 cd/m2, which is significantly higher than the cell using only the FTO electrode (450 cd/m2). The nanoporous ITO layer was effective in increasing the ECL intensities. PMID:22849163

Chaoumead, Accarat; Kim, Tae-Woo; Park, Min-Woo; Sung, Youl-Moon

2012-04-01

263

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

SciTech Connect

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.

Wallace, W.L.

1983-06-01

264

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

SciTech Connect

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.

Wallace, W.L.

1983-05-01

265

Music Generated by a Zn/Cu Electrochemical Cell, a Lemon Cell, and a Solar Cell: A Demonstration for General Chemistry  

ERIC Educational Resources Information Center

The circuit board found in a commercial musical greeting card is used to supply music for electrochemical cell demonstrations. Similar to a voltmeter, the "modified" musical device is connected to a chemical reaction that produces electricity. The commercial 1 V battery inside the greeting card circuit board can be replaced with an…

Cady, Susan G.

2014-01-01

266

One step preparation and electrochemical analysis of IQS, a cell-cell communication signal in the nosocomial pathogen Pseudomonas aeruginosa.  

PubMed

Pseudomonas aeruginosa uses a hierarchical cell-cell communication system consisting of a number of regulatory elements to coordinate the expression of bacterial virulence genes. Sensitive detection of quorum sensing (QS) molecules has the potential for early identification of P. aeruginosa facilitating early medical intervention. A recently isolated cell-cell communication molecule, a thiazole termed IQS, can bypass the las QS system of P. aeruginosa under times of stress, activating a subset of QS-controlled genes. This compound offers a new target for pathogen detection and has been prepared in a one step protocol. A simple electrochemical strategy was employed for its sensitive detection using boron-doped diamond and glassy carbon electrodes by cyclic voltammetry and amperometry. PMID:25190465

Shang, Fengjun; Muimhneacháin, Eoin Ó; Jerry Reen, F; Buzid, Alyah; O'Gara, Fergal; Luong, John H T; Glennon, Jeremy D; McGlacken, Gerard P

2014-10-01

267

Lack of Relation between Secondary Hyperparathyroidism and Red Blood Cell Osmotic Fragility in Chronic Renal Failure  

Microsoft Academic Search

The possible relationship between red blood cell (RBC) osmotic fragility and secondary hyperparathyroidism (HPT) in chronic renal failure was examined in 23 uremic patients on conservative therapy and in 42 patients on maintenance hemodialysis. Secondary HPT was evaluated by means of serum biochemistry (parathyroid hormone, calcium, phosphorus, and alkaline phosphatase) and radiographic examinations (X-ray films of the hand skeleton). This

Dino Docci; Fausto Turci; Leopoldo Baldrati

1985-01-01

268

Laccases direct lignification in the discrete secondary cell wall domains of protoxylem.  

PubMed

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

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

2014-10-01

269

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

PubMed Central

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

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

2014-01-01

270

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

DOEpatents

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.

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

271

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

DOEpatents

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 C to 1300 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. 6 figs.

Spengler, C.J.; Folser, G.R.; Vora, S.D.; Kuo, L.; Richards, V.L.

1995-06-20

272

Electrochemical monitoring of an important biomarker and target protein: VEGFR2 in cell lysates  

PubMed Central

Vascular endothelial growth factor receptor 2 (VEGFR2) is a potential cell-type biomarker in clinical diagnoses. Besides, it's the target protein of many tyrosine kinase inhibitors and its expression significantly associates with clinical performance of these inhibitors. VEGFR2 detection provides an early warning for diseases and a basis for therapy and drug screening. Some methods have been developed for VEGFR2 determination. However, they are usually performed indirectly and complexly. Herein, an electrochemical biosensing platform for VEGFR2 analysis has been first proposed. It can detect the total concentrations of the VEGFR2 protein in cells lysates directly and can be used to monitor the changes of VEGFR2 expression levels induced by treatments of different inhibitors. Moreover, the inhibitor-VEGFR2 interactions are illuminated through theoretical simulation. The simulation results agree well with the experimental data, indicating the veracity of the proposed method. The electrochemical detection methodology for VEGFR2 would be promising in clinical diagnosis and drug screening. PMID:24496270

Wei, Tianxiang; Tu, Wenwen; Zhao, Bo; Lan, Yaqian; Bao, Jianchun; Dai, Zhihui

2014-01-01

273

Reaction of SbPO 4 with lithium in non-aqueous electrochemical cells: preliminary study and evaluation of its electrochemical performance in anodes for lithium ion batteries  

NASA Astrophysics Data System (ADS)

SbPO 4, a phosphate with a layered structure, was tested as an electrode material for lithium cells spanning the 3.0-0.0 V range. Two main electrochemical processes were detected as extensive plateaus at ca. 1.6 and 0.7 V in galvanostatic measurements. The first process was found to be irreversible, thus excluding a potential intercalation-like mechanism for the reaction and being better interpreted as a decomposition reaction leading to the formation of elemental Sb. This precludes the use of this compound as a cathodic material for lithium cells. By contrast, the process at 0.7 V is reversible and can be ascribed to the formation of lithium-antimony alloys. The best electrochemical response was obtained by cycling the cell at a C/20 discharge rate over the voltage range 1.25-0.25 V. Under these conditions, the cell delivers an average capacity of 165 Ah/kg—a value greater than those reported for other phosphates—upon successive cycling.

Santos Peña, J.; Cuart Pascual, J.; Caballero, A.; Morales, J.; Sánchez, L.

2004-08-01

274

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

PubMed

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

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

2014-10-24

275

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

276

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

DOEpatents

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.

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

1999-01-01

277

Secondary Structure of Cell-Penetrating Peptides Controls Membrane Interaction and Insertion  

E-print Network

Secondary Structure of Cell-Penetrating Peptides Controls Membrane Interaction and Insertion Emelía permeability of the biological membranes. In order to enhance their cell delivery, short amphipathic peptides called cell-penetrating peptides (CPPs) have been intensively developed for the last two decades. CPPs

Boyer, Edmond

278

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

PubMed

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

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

2009-07-01

279

Electrochemical device  

DOEpatents

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.

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

1988-01-12

280

Electrochemical construction  

DOEpatents

An electrochemical cell construction features a novel co-extruded plastic electrode in an interleaved construction with a novel integral separator-spacer. Also featured is a leak and impact resistant construction for preventing the spill of corrosive materials in the event of rupture.

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

1983-08-23

281

A new disposable electrode for electrochemical study of leukemia K562 cells and anticancer drug sensitivity test.  

PubMed

Developing cost-effective and simple analysis tools is of vital importance for practical applications in bioanalysis. In this work, a new disposable electrochemical cell sensor with low cost and simple fabrication was proposed to study the electrochemical behavior of leukemia K562 cells and the effect of anticancer drugs on cell viability. The analytical device was integrated by using ITO glass as the substrate of working electrodes and paper as the electrolytic cell. The cyclic voltammetry of the K562 cells at the disposable electrode exhibited an irreversible anodic peak and the peak current is proportional to the cell number. This anodic peak is attributed to the oxidation of guanine in cells involving two protons per transfer of two electrons. For the drug sensitivity tests, arsenic trioxide and cyclophosphamide were added to cell culture media. As a result, the electrochemical responses of the K562 cells decreased significantly. The cytotoxicity curves and results obtained corresponded well with the results of CCK-8 assays. In comparison to conventional methods, the proposed method is simple, rapid and inexpensive. More importantly, the developed sensor is supposed to be a single-use disposable device and electrodes were prepared "as new" for each experiment. We think that such disposable electrodes with these characteristics are suitable for experimental study with cancer cells or other types of pathogens for disease diagnosis, drug selection and on-site monitoring. PMID:24140828

Yu, Chunmei; Zhu, Zhenkun; Wang, Li; Wang, Qiuhong; Bao, Ning; Gu, Haiying

2014-03-15

282

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

SciTech Connect

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.

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

2002-06-21

283

Identification of transcription factors involved in rice secondary cell wall formation.  

PubMed

Using co-expression network analysis, we identified 123 transcription factors (TFs) as candidate secondary cell wall regulators in rice. To validate whether these TFs are associated with secondary cell wall formation, six TF genes belonging to the MYB, NAC or homeodomain-containing TF families were overexpressed or downregulated in rice. With the exception of OsMYB58/63-RNAi plants, all transgenic plants showed phenotypes possibly related to secondary cell wall alteration, such as dwarfism, narrow and dark green leaves, and also altered rice cinnamyl alcohol dehydrogenase 2 (OsCAD2) gene expression and lignin content. These results suggest that many of the 123 candidate secondary cell wall-regulating TFs are likely to function in secondary cell wall formation in rice. Further analyses were performed for the OsMYB55/61 and OsBLH6 TFs, the former being a TF in which the Arabidopsis ortholog is known to participate in lignin biosynthesis (AtMYB61) and the latter being one for which no previous involvement in cell wall formation has been reported even in Arabidopsis (BLH6). OsMYB55/61 and OsBLH6-GFP fusion proteins localized to the nucleus of onion epidermal cells. Moreover, expression of a reporter gene driven by the OsCAD2 promoter was enhanced in rice calli when OsMYB55/61 or OsBLH6 was transiently expressed, demonstrating that they function in secondary cell wall formation. These results show the validity of identifying potential secondary cell wall TFs in rice by the use of rice co-expression network analysis. PMID:24089432

Hirano, Ko; Kondo, Mari; Aya, Koichiro; Miyao, Akio; Sato, Yutaka; Antonio, Baltazar A; Namiki, Nobukazu; Nagamura, Yoshiaki; Matsuoka, Makoto

2013-11-01

284

Degradation Mechanisms of Electrochemically Cycled Graphite Anodes in Lithium-ion Cells  

NASA Astrophysics Data System (ADS)

This research is aimed at developing advanced characterization methods for studying the surface and subsurface damage in Li-ion battery anodes made of polycrystalline graphite and identifying the degradation mechanisms that cause loss of electrochemical capacity. Understanding microstructural aspects of the graphite electrode degradation mechanisms during charging and discharging of Li-ion batteries is of key importance in order to design durable anodes with high capacity. An in-situ system was constructed using an electrochemical cell with an observation window, a large depth-of-field digital microscope and a micro-Raman spectrometer. It was revealed that electrode damage by removal of the surface graphite fragments of 5-10 mum size is the most intense during the first cycle that led to a drastic capacity drop. Once a solid electrolyte interphase (SEI) layer covered the electrode surface, the rate of graphite particle loss decreased. Yet, a gradual loss of capacity continued by the formation of interlayer cracks adjacent to SEI/graphite interfaces. Deposition of co-intercalation compounds, LiC6, Li2CO3 and Li2O, near the crack tips caused partial closure of propagating graphite cracks during cycling and reduced the crack growth rate. Bridging of crack faces by delaminated graphite layers also retarded crack propagation. The microstructure of the SEI layer, formed by electrochemical reduction of the ethylene carbonate based electrolyte, consisted of ˜5-20 nm sized crystalline domains (containing Li2CO3, Li2O 2 and nano-sized graphite fragments) dispersed in an amorphous matrix. During the SEI formation, two regimes of Li-ion diffusion were identified at the electrode/electrolyte interface depending on the applied voltage scan rate (dV/dt). A low Li-ion diffusion coefficient ( DLi+) at dV/dt < 0.05 mVs-1 produced a tubular SEI that uniformly covered the graphite surface and prevented damage at 25°C. At 60°C, a high D Li+ formed a Li2CO3-enriched SEI and ensued a 28% increase in the battery capacity at 25°C. On correlating the microscopic information to the electrochemical performance, novel Li2CO3-coated electrodes were fabricated that were durable. The SEI formed on pre-treated electrodes reduced the strain in the graphite lattice from 0.4% (for uncoated electrodes) to 0.1%, facilitated Li-ion diffusion and hence improved the capacity retention of Li-ion batteries during long-term cycling.

Bhattacharya, Sandeep

285

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

PubMed

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

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

2014-10-01

286

Concentration of carbon dioxide by a high-temperature electrochemical membrane cell  

NASA Technical Reports Server (NTRS)

The performance of a molten carbonate carbon dioxide concentrator (MCCDC) cell, as a device for removal of CO2 from manned spacecraft cabins without fuel expenditure, is investigated. The test system consists of an electrochemical cell (with an Li2CO3-38 mol pct K2CO3 membrane contained in a LiAlO2 matrix), a furnace, and a flow IR analyzer for monitoring CO2. Operation of the MCCDC-driven cell was found to be suitable for the task of CO2 removal: the cell performed at extremely low CO2 partial pressures (at or above 0.1 mm Hg); cathode CO2 efficiencies of 97 percent were achieved with 0.25 CO2 inlet concentration at 19 mA sq cm, at temperatures near 873 K. Anode concentrations of up to 5.8 percent were obtained. Simple cathode and anode performance equations applied to correlate cell performance agreed well with those measured experimentally. A flow diagram for the process is included.

Kang, M. P.; Winnick, J.

1985-01-01

287

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

SciTech Connect

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.

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

2005-07-01

288

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

NASA Technical Reports Server (NTRS)

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.

Baldwin, Richard S.

1987-01-01

289

Periodic, quasiperiodic, and chaotic potentials generated by electrochemical concentration cells: Local and global dynamics  

NASA Astrophysics Data System (ADS)

We extend previous work describing the passive electrical coupling of two periodic chemical states to include quasiperiodic and chaotic states. Our setup resembles an electrochemical concentration cell (a battery) whose half cells [continuous-flow stirred tank reactors (CSTRs)] each contain the Belousov-Zhabotinsky (BZ) reaction. For a closed electrical circuit the two half cells are weakly coupled by an external variable resistance and by a constant low mass flow. This battery may produce either periodic, quasiperiodic, or chaotic alternating current depending on the dynamic BZ states chosen in the half cells. A lower fractal dimensionality is calculated from the electrical potential of a single chaotic CSTR than from the difference potential (relative potential) of the two chaotic half cell potentials. A similar situation is observed in model calculations of a chaotic spatiotemporal system (the driven Brusselator in one space dimension) where the dimensionality derived from a local time series is lower than the dimensionality of the global trajectory calculated from the Karhunen-Loeve coefficients.

Zeyer, K.-P.; Münster, A. F.; Hauser, M. J. B.; Schneider, F. W.

1994-09-01

290

Glucose and Lactate Biosensors for Scanning Electrochemical Microscopy Imaging of Single Live Cells  

PubMed Central

We have developed glucose and lactate ultramicroelectrode (UME) biosensors based on glucose oxidase and lactate oxidase (with enzymes immobilized onto Pt UMEs by either electropolymerization or casting) for scanning electrochemical microscopy (SECM), and have determined their sensitivity to glucose and lactate, respectively. The results of our evaluations reveal different advantages for sensors constructed by each method: improved sensitivity and shorter manufacturing time for hand-casting, and increased reproducibility for electropolymerization. We have acquired amperometric approach curves (ACs) for each type of manufactured biosensor UME, and these ACs can be used as a means of positioning the UME above a substrate at a known distance. We have used the glucose biosensor UMEs to record profiles of glucose uptake above individual fibroblasts. Likewise, we have employed the lactate biosensor UMEs for recording the lactate production above single cancer cells with the SECM. We also show that oxygen respiration profiles for single cancer cells do not mimic cell topography, but are rather more convoluted, with a higher respiration activity observed at the points where the cell touches the Petri dish. These UME biosensors, along with the application of others already described in the literature, could prove to be powerful tools for mapping metabolic analytes, such as glucose, lactate and oxygen, in single cancer cells. PMID:18345647

Ciobanu, Madalina; Taylor, Dale E.; Wilburn, Jeremy P.; Cliffel, David E.

2010-01-01

291

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

NASA Astrophysics Data System (ADS)

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).

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

2014-10-01

292

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

PubMed

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

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

2014-10-01

293

Applications of advanced electrochemical techniques in the study of microbial fuel cells and corrosion protection by polymer coatings  

Microsoft Academic Search

The results of a detailed evaluation of the properties of the anode and the cathode of a mediator-less microbial fuel cell (MFC) and the factors determining the power output of the MFC using different electrochemical techniques are presented in Chapter 1. In the MFC under investigation, the biocatalyst - Shewanella oneidensis MR-1 - oxidizes the fuel and transfers the electrons

Aswin Karthik Manohar

2010-01-01

294

Evaluation of polymer electrolyte membrane fuel cells by electrochemical impedance spectroscopy under different operation conditions and corrosion  

Microsoft Academic Search

Electrochemical impedance spectroscopy (EIS) was employed for in situ diagnosis for polymer electrolyte membrane fuel cells during operation. First, EIS was measured as a function of operation parameters such as applied current density, gas flow rates and gas humidification temperature. The resistance that correlated with conductivity of the membrane and the contact resistance between bipolar plate and gas diffusion layer

Masanobu Kumagai; Seung-Taek Myung; Takuma Ichikawa; Hitoshi Yashiro

2010-01-01

295

Creating systems that effectively convert energy, such as efficient solar cells and electrochemical batteries, has been a  

E-print Network

SEMTE abstract Creating systems that effectively convert energy, such as efficient solar cells stimuli, the solar energy from sunlight, and the mechanical motion is commonplace, indeed fundamental and electrochemical batteries, has been a longstanding scientific pursuit, especially given the global energy

Reisslein, Martin

296

Printed electronics: inkjet printed bilayer light-emitting electrochemical cells for display and lighting applications (small 20/2014).  

PubMed

On page 4148, L. Edman and co-workers introduce an inkjet-based, mask free, and additive patterning technique for light-emitting electrochemical cells. The position and size of the pixels correspond directly to those of the inkjet-deposited electrolyte droplets. PMID:25333224

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

2014-10-01

297

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

E-print Network

in continuous flow. Parasitic current flow did not appreciably impact reactor performance. a r t i c l e i n fElectrochemical study of multi-electrode microbial fuel cells under fed-batch and continuous flow connections. Polarization tests were needed to compare individual reactors with combined MFCs. Same power

298

Microfluidic chip integrated with flexible PDMS-based electrochemical cytosensor for dynamic analysis of drug-induced apoptosis on HeLa cells.  

PubMed

A novel microfluidic platform integrated with a flexible PDMS-based electrochemical cytosensor was developed for real-time monitoring of the proliferation and apoptosis of HeLa cells. The PDMS-gold film, which had a conductive smooth surface and was semi-transparent, facilitated electrochemical measurements and optical microscope observations. We observed distinct increases and decreases in peak current intensity, corresponding to cell proliferation in culture medium and apoptosis in the presence of an anticancer drug, respectively. This electrochemical analysis method permitted real-time, label-free monitoring of cell behavior, and the electrochemical results were confirmed with optical microscopy. The flexible microfluidic electrochemical platform presented here is suitable for on-site monitoring of cell behavior in microenvironments. PMID:23942358

Cao, Jun-Tao; Zhu, Ying-Di; Rana, Rohit Kumar; Zhu, Jun-Jie

2014-01-15

299

A sodium/beta-alumina/nickel chloride secondary cell  

NASA Astrophysics Data System (ADS)

Nickel chloride has been studied in a cell system, sodium/beta alumina/sodium tetrachloroaluminate/nickel chloride, which is analogous to two existing rechargeable high energy density cells based on iron chloride and sodium sulfur. The cell reaction can be written as: 2Na + NiCl2 yields on discharge Ni + 2NaCl. The positive electrode, conveniently assembled in the discharged state, was a nickel/sodium choride sinter. Molten sodium tetrachloroaluminate electrolyte (NaAlCl4) acted as intermediate between electrode and beta alumina tube. Encouraging results were obtained in terms of low resistances and rates of discharge for cells up to 20-Ah capacity. Cells were operated over the temperature range from 230 to 400 C where the OCV of the cell reaction varied from 2.60 V to 2.56 V.

Galloway, R. C.

1987-01-01

300

In situ screening for genes expressed preferentially in secondary mesenchyme cells of sea urchin embryos  

Microsoft Academic Search

In sea urchin embryos, four types of non-skeletogenic mesodermal cells are derived from secondary mesenchyme cells (SMCs). Although determining the complete lineage of SMCs is currently a high-priority goal, specific markers for each type of SMC-derived cell in Hemicentrotus pulcherrimus are unavailable. To identify genes preferentially expressed in the various types of SMC-derived cells, we constructed a cDNA library of

Eiichi Shoguchi; Miki Tokuoka; Tetsuya Kominami

2002-01-01

301

Thermodynamic relation between voltage-concentration dependence and salt adsorption in electrochemical cells.  

PubMed

Electrochemical cells containing two electrodes dipped in an ionic solution are widely used as charge accumulators, either with polarizable (supercapacitor) or nonpolarizable (battery) electrodes. Recent applications include desalination ("capacitive deionization") and energy extraction from salinity differences ("capacitive mixing"). In this Letter, we analyze a general relation between the variation of the electric potential as a function of the concentration and the salt adsorption. This relation comes from the evaluation of the electrical and mechanical energy exchange along a reversible cycle, which involves salt adsorption and release by the electrodes. The obtained relation thus describes a connection between capacitive deionization and capacitive mixing. We check this relation with experimental data already reported in the literature, and moreover by some classical physical models for electrodes, including polarizable and nonpolarizable electrodes. The generality of the relation makes it very useful in the study of the properties of the electric double layer. PMID:23102339

Rica, R A; Ziano, R; Salerno, D; Mantegazza, F; Brogioli, D

2012-10-12

302

Double-layer formation in organic light-emitting electrochemical cells  

NASA Astrophysics Data System (ADS)

We present a systematic analysis of the current transients accompanying the formation of the electrode-electrolyte double layers in organic light-emitting electrochemical cells. By using various room-temperature molten salts, conducting polymers, and electrodes, we show that the current I always decreases as a power law of time, I[is proportional to]t-n. The current transients are formed of various time domains, each one being characterized by a power-law exponent n<1. Impedance measurements conducted from 5 Hz to 5 MHz demonstrate that these transients represent the time response of a simple combination of constant phase angle (CPA) impedances, Zn[is proportional to](jomega)n, and of the electrolyte ionic conductivity. The physical origin of the CPA impedance is attributed to the roughness of the interface between the electrodes and the electrolyte, and to the phase separation within the salt-polymer blend.

Ouisse, T.; Stephan, O.; Armand, M.; Lepretre, J. C.

2002-09-01

303

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

NASA Astrophysics Data System (ADS)

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.

Voß, S.; Kollmann, H.; Kollmann, W.

304

Structural, thermal and electrochemical cell characteristics of poly(vinyl chloride)-based polymer electrolytes  

NASA Astrophysics Data System (ADS)

A study is made of a polymer electrolyte system composed of poly(vinyl chloride) (PVC) as a host polymer, lithium tetrafluoroborate (LiBF 4) and lithium triflate (LiCF 3SO 3) as salts and a mixture of ethylene carbonate and propylene carbonate as plasticizers. X-ray diffraction (XRD) reveales that the salts and plasticizers disrupt the crystalline nature of PVC-based polymer electrolytes and converts them into an amorphous phase. Differential scanning calorimetry studies suggest that the plasticized samples have lower values of the glass tranisition temperature Tg, and thermogravimetric studies show that the thermal stability of the polymer electrolytes decreases with addition of plasticizers. The plasticized PVC electrolyte is used in the fabrication of electrochemical cells. The open-circuit voltage, discharge time for the plateau region, etc. are evaluated.

Ramesh, S.; Arof, A. K.

305

Combining microbial cultures for efficient production of electricity from butyrate in a microbial electrochemical cell.  

PubMed

Butyrate is an important product of anaerobic fermentation; however, it is not directly used by characterized strains of the highly efficient anode respiring bacteria (ARB) Geobacter sulfurreducens in microbial electrochemical cells. By combining a butyrate-oxidizing community with a Geobacter rich culture, we generated a microbial community which outperformed many naturally derived communities found in the literature for current production from butyrate and rivaled the highest performing natural cultures in terms of current density (?11A/m(2)) and Coulombic efficiency (?70%). Microbial community analyses support the shift in the microbial community from one lacking efficient ARB in the marine hydrothermal vent community to a community consisting of ?80% Geobacter in the anode biofilm. This demonstrates the successful production and adaptation of a novel microbial culture for generating electrical current from butyrate with high current density and high Coulombic efficiency, by combining two mixed microbial cultures containing complementing biochemical pathways. PMID:25048958

Miceli, Joseph F; Garcia-Peña, Ines; Parameswaran, Prathap; Torres, César I; Krajmalnik-Brown, Rosa

2014-10-01

306

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

SciTech Connect

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.

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

307

Processing, microstructural evolution and electrochemical performance relationships in solid oxide fuel cells  

NASA Astrophysics Data System (ADS)

The relationships between the processing parameters, microstructures and electrochemical performance of solid oxide fuel cell (SOFC) components were investigated. The operating regimes (i.e., reducing vs. oxidizing) as well as the elevated temperatures (e.g. 800°C) for their operation introduce several material challenges. Therefore, composite materials are employed to withstand operating conditions while providing sufficient electrochemical performance for fuel cell operation. Analyses on lanthanum-strontium manganite (LSM) - yttria stabilized zirconia (YSZ) compositions (45 vol%-55 vol%) by impedance spectroscopy demonstrated that two competing polarization mechanisms (i.e. charge-exchange and surface adsorption-diffusion of oxygen) limit performance. Optimization of microstructures resulted in total resistances as low as 0.040 Ohm cm2. Studies on Ag composites revealed that incorporation of up to 25 vol% oxide particles (LSM and YSZ) with sizes comparable to the Ag grains (~0.5 microm) can minimize the densification and coarsening of the Ag matrix. While the powder based oxide additions increased the stability limit of porous Ag composites from <550°C to 800°C, the use of nanostructured coatings increased the stability limit to 900°C for cathodes and current collectors. Investigations of Ni-YSZ anode microstructures demonstrated that uniform distribution of percolating isometric pores (>5 microm) allows forming desired continuous percolation of all phases (Ni, YSZ and pores) lowering activation polarization below 0.100 Ohm cm2 and maintaining significant electrical conductivity (>1000 S/cm). Identification of polarization mechanisms by deconvolution of impedance spectra and tailoring the corresponding microstructures was demonstrated as an effective method for optimization of SOFC components.

Sarikaya, Ayhan

308

Coupled electrochemical and heat/mass transport characteristics in passive direct methanol fuel cells  

NASA Astrophysics Data System (ADS)

This thesis presents both experimental and theoretical investigations of coupled heat/mass transfer and electrochemical characteristics in the passive DMFC. Unlike active fuel cells, which can be operated under stabilized operating conditions, the discharging behavior of the passive DMFC usually varies with time, as the methanol concentration in the fuel reservoir decreases with time. This poses a difficulty in characterizing the performance of the passive DMFC under relatively stable operating conditions. In this work, we found that the performance of the passive DMFC became relatively stable as the cell operating temperature rose to a relatively stable value. This finding indicates that the performance of the passive DMFC can be characterized by collecting polarization data at the instance when the cell operating temperature under the open-circuit condition rises to a relatively stable value. With this proposed standard of passive DMFC performance characterization, the effects of two important parameters, including methanol concentration and cell orientation, on the passive DMFC performance were then investigated. It is found that the cell performance increased with methanol concentration. Unlike previous studies that attributed the improved performance as a result of increasing methanol concentration to the reduced anode mass transport polarization, our experimental results revealed that the improved cell performance was primarily due to the increased cell operating temperature as a result of the increased rate of methanol crossover with high methanol concentration operation. We also found that the performance was sensitive to the cell orientation. The vertical operation always yielded better performance than did the horizontal operation. This can be attributed to the increased operating temperature as a result of a higher rate of methanol crossover, which resulted from the stronger natural convection in the vertical orientation. These parametric studies indicated that the thermal management is a key factor for improving the performance of the passive DMFC. To enhance oxygen transport on the air-breathing cathode and to reduce the heat loss from the cathode, a porous current collector for the passive DMFC was proposed to replace conventional perforated-plate current collectors. Because of its high specific area of transport and effectiveness in removing the liquid water as a result of the capillary action in the porous structure, the porous current collector enables a significant enhancement of oxygen supply to the fuel cell. In addition, because of the lower effective thermal conductivity of the porous structure, the heat loss from the fuel cell to ambient air can be reduced. The experimental results showed that the passive DMFC having the porous current collector yielded much higher and much more stable performance than did the cell having the conventional perforated-plate current collector with high methanol concentration operation. As a following up to oxygen transport enhancement, a new design of membrane electrode assembly (MEA) was proposed, in which the conventional cathode gas diffusion layer (CGDL) is eliminated while utilizing a porous metal structure for transporting oxygen and collecting current. We show theoretically that the new MEA enables a higher mass transfer rate of oxygen and thus better performance. Moreover, the measured polarization and constant-current discharging behavior showed that the passive DMFC with the new MEA yielded higher and much more stable performance than did the cell having the conventional MEA. Besides the experimental investigations, to further theoretically study the thermal effect on the cell performance, a one-dimension single-phase model is developed by considering inherently coupled heat and mass transport along with the electrochemical reactions occurring in passive DMFCs. The analytical solutions predicting the performance of this type of fuel cell operating with different methanol concentrations are obtained. It was further revealed that the improved performance with

Chen, Rong

309

Embolization for Treatment of Gastrointestinal Hemorrhage Secondary to Recurrent Renal Cell Carcinoma  

SciTech Connect

Massive gastrointestinal hemorrhage secondary to metastatic renal cell carcinoma involving the jejunum is rare but has been previously described in the medical literature. Treatment options for metastatic renal cell carcinoma are limited, but transcatheter arterial embolization can be performed to control gastrointestinal hemorrhage either alone or prior to surgical resection. We describe a case of successful transcatheter arterial embolization for control of massive gastrointestinal hemorrhage secondary to locally recurrent renal cell carcinoma invading the jejunum and review the literature. Arteriography provided both the diagnosis of recurrent disease and the means of therapy.

Kobak, Jeff [SUNY Downstate Health Science Center, Department of Radiology (United States); Gandras, Eric J. [North Shore University Hospital, Department of Radiology (United States)], E-mail: egandrobi@aol.com; Fleury, Linwald; Macura, Jerzy [Maimonides Medical Center, Department of Surgery (United States); Shams, Joseph [Beth Israel Medical Center, Department of Radiology (United States)

2006-12-15

310

Design, evaluation, and application of continuous-flow cells for organic electrochemical synthesis. Final report  

SciTech Connect

Two examples of the oxidation and reduction of aldehydes as a paired synthesis have been studied. These are model systems for potential energy savings in organic electrochemical synthesis. Both are indirect processes; the reduction via alkali metal amalgam and the oxidation via hypobromite. One, using furfural as the substrate, has proved unsuccessful due to the oxidation of its reduction products with the electrogenerated oxidant, bromine. The other paired synthesis, using glucose, has been operated successfully in two types of parallel plate flow cells and two types of porous, packed bed flow cells. To date, the optimum electrode materials and operating conditions for the glucose paired reaction, as determined by product yields and current efficiencies, are an amalgamated zinc cathode, a graphite anode, an initial glucose concentration of 0.8M, a 0.8M NaBr supporting electrolyte and an electrolyte flow rate of 0.8 1/min. Both constant current (10 mA/cm/sup 2/) and constant cathode potential (-2.10V vs SCE) electrolyses were performed under the above conditions. Electrolyses carried out in the parallel plate flow cell and the packed bed flow cell in which the current and electrolyte flow are parallel to one another gave comparable results. Lower current efficiencies were obtained in the porous, packed bed flow cell with perpendicular current and flow. The reasons for the poorer results in the perpendicular configuration cell are not known at this time and further experimentation is required with this system. The current efficiencies and yields of both the oxidation reaction (the production of gluconic acid) and the reduction reaction (the formation of sorbitol) in the packed bed cells were found to be dependent on solution pH.

Nobe, K.

1982-09-30

311

Electrochemical behavior of heavily cycled nickel electrodes in Ni/H2 cells containing electrolytes of various KOH concentrations  

NASA Technical Reports Server (NTRS)

A study has been made of charge and discharge voltage changes with cycling of Ni/H2 cells containing electrolytes of various KOH concentrations. A study has also been made of electrochemical behavior of the nickel electrodes from the cycled Ni/H2 cells as a function of overcharge amounts. Discharge voltages depressed gradually with cycling for cells having high KOH concentrations (31 to 36 percent), but the voltages increased for those having low KOH concentrations (21 to 26 percent). To determine if there was a crystallographic change of the active material due to cycling, electrochemical behavior of nickel electrodes was studied in an electrolyte flooded cell containing either 31 or 26 percent KOH electrolyte as a function of the amount of overcharge. The changes in discharge voltage appear to indicate crystal structure changes of active material from gamma-phase to beta-phase in low KOH concentrations, and vice versa in high KOH concentration.

Lim, H. S.; Verzwyvelt, S. A.

1989-01-01

312

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

PubMed

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

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

2013-01-01

313

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

PubMed Central

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

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

2013-01-01

314

From microbial fuel cell (MFC) to microbial electrochemical snorkel (MES): maximizing chemical oxygen demand (COD) removal from wastewater.  

PubMed

The paper introduces the concept of the microbial electrochemical snorkel (MES), a simplified design of a "short-circuited" microbial fuel cell (MFC). The MES cannot provide current but it is optimized for wastewater treatment. An electrochemically active biofilm (EAB) was grown on graphite felt under constant polarization in an urban wastewater. Controlling the electrode potential and inoculating the bioreactor with a suspension of an established EAB improved the performance and the reproducibility of the anodes. Anodes, colonized by an EAB were tested for the chemical oxygen demand (COD) removal from urban wastewater using a variety of bio-electrochemical processes (microbial electrolysis, MFC, MES). The MES technology, as well as a short-circuited MFC, led to a COD removal 57% higher than a 1000 ?-connected MFC, confirming the potential for wastewater treatment. PMID:21409654

Erable, Benjamin; Etcheverry, Luc; Bergel, Alain

2011-03-01

315

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

316

Ageing combines CD4 T cell lymphopenia in secondary lymphoid organs and T cell accumulation in gut associated lymphoid tissue  

PubMed Central

Background CD4 T cell lymphopenia is an important T cell defect associated to ageing. Higher susceptibility to infections, cancer, or autoimmune pathologies described in aged individuals is thought to partly rely on T cell lymphopenia. We hypothesize that such diverse effects may reflect anatomical heterogeneity of age related T cell lymphopenia. Indeed, no data are currently available on the impact of ageing on T cell pool recovered from gut associated lymphoid tissue (GALT), a crucial site of CD4 T cell accumulation. Results Primary, secondary and tertiary lymphoid organs of C57BL/6 animals were analysed at three intervals of ages: 2 to 6 months (young), 10 to 14 months (middle-aged) and 22 to 26 months (old). We confirmed that ageing preferentially impacted CD4 T cell compartment in secondary lymphoid organs. Importantly, a different picture emerged from gut associated mucosal sites: during ageing, CD4 T cell accumulation was progressively developing in colon and small intestine lamina propria and Peyer’s patches. Similar trend was also observed in middle-aged SJL/B6 F1 mice. Interestingly, an inverse correlation was detected between CD4 T cell numbers in secondary lymphoid organs and colonic lamina propria of C57BL/6 mice whereas no increase in proliferation rate of GALT CD4 T cells was detected. In contrast to GALT, no CD4 T cell accumulation was detected in lungs and liver in middle-aged animals. Finally, the concomitant accumulation of CD4 T cell in GALT and depletion in secondary lymphoid organs during ageing was detected both in male and female animals. Conclusions Our data thus demonstrate that T cell lymphopenia in secondary lymphoid organs currently associated to ageing is not sustained in gut or lung mucosa associated lymphoid tissues or non-lymphoid sites such as the liver. The inverse correlation between CD4 T cell numbers in secondary lymphoid organs and colonic lamina propria and the absence of overt proliferation in GALT suggest that marked CD4 T cell decay in secondary lymphoid organs during ageing reflect redistribution of CD4 T cells rather than generalized CD4 T cell decay. Such anatomical heterogeneity may provide an important rationale for the diversity of immune defects observed during ageing. PMID:24829607

2014-01-01

317

Patient fears of tumor cell dissemination secondary to surgical interventions-part II.  

PubMed

Patient fears are an ever-present factor of patient care, and addressing those fears is a responsibility of the healthcare provider. One such fear may be of tumor cell dissemination secondary to surgical interventions. Preparing for such discussions will allow the healthcare provider to speak with authority on the topic of tumor dissemination secondary to breast biopsy or surgery, even in a situation where a patient has underlying fears. PMID:24476734

McClelland, Stacy; Weiss, Patricia

2014-02-01

318

Secretion of Secondary Metabolites by ATP-Binding Cassette Transporters in Plant Cell Suspension Cultures1  

Microsoft Academic Search

The substrate specificity of the yeast (Saccharomyces cerevisiae) pleiotropic drug resistance (PDR)-type ATP-binding cassette (ABC) transporters is extended to plant secondary metabolites of the tropane alka- loid family. Functional analysis of yeast PDR5 genes in transgenic tobacco (Nicotiana tabacum L. cv Bright- Yellow 2 (BY-2)) cell lines suggest that PDR genes can be used to stimulate the secretion of secondary

Alain Goossens; Suvi T. Hakkinen; Kirsi-Marja Oksman-Caldentey; Dirk Inze ´

319

A new electrochemical method for the detection of cancer cells based on small molecule-linked DNA.  

PubMed

Sensitive and accurate detection of cancer cells plays a crucial role in clinical diagnosis, treatment and prognosis of tumors. In this paper, we report a new electrochemical method for highly selective and sensitive detection of cancer cells by using small molecule-linked DNA as probes. The methodology is based on the fact that exonuclease I can catalyze the digestion of folate-linked DNA probes that are immobilized on an electrode surface; however, in the presence of the target cells, such as human breast cancer MCF-7 cells, the probes can be protected from digestion upon the binding with folate receptor that is over-expressed on the cell surface. Consequently, cancer cells can be efficiently detected by monitoring the status of the probe DNA with electrochemical techniques. In this study, the protection to exonuclease I-catalyzed digestion has also been proven by electrochemical studies. Moreover, the proposed method has been proven to linearly detect MCF-7 cells in a wide range from 10(2)-10(6) cell mL(-1) with a low detection limit of 67 cell mL(-1), which can also easily distinguish the folate receptor-negative normal cells, for instance, islet ? cells. The reproduction of the detection is also satisfactory, since the relative standard deviations for three independent measurements of different concentration of MCF-7 cells are all within 10%. By replacing the small molecules linked on the DNA probe, other cancer cells can also be detected by making use of this proposed method. Therefore, our cytosensor may have great potential in clinical applications. PMID:23796531

Zhao, Jing; Zhu, Li; Guo, Chao; Gao, Tao; Zhu, Xiaoli; Li, Genxi

2013-11-15

320

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

SciTech Connect

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.

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

2012-01-01

321

Multichannel bipotentiostat integrated with a microfluidic platform for electrochemical real-time monitoring of cell cultures.  

PubMed

An electrochemical detection system specifically designed for multi-parameter real-time monitoring of stem cell culturing/differentiation in a microfluidic system is presented. It is composed of a very compact 24-channel electronic board, compatible with arrays of microelectrodes and coupled to a microfluidic cell culture system. A versatile data acquisition software enables performing amperometry, cyclic voltammetry and impedance spectroscopy in each of the 12 independent chambers over a 100 kHz bandwidth with current resolution down to 5 pA for 100 ms measuring time. The design of the platform, its realization and experimental characterization are reported, with emphasis on the analysis of impact of input capacitance (i.e., microelectrode size) and microfluidic pump operation on current noise. Programmable sequences of successive injections of analytes (ferricyanide and dopamine) and rinsing buffer solution as well as the impedimetric continuous tracking for seven days of the proliferation of a colony of PC12 cells are successfully demonstrated. PMID:23853236

Vergani, Marco; Carminati, Marco; Ferrari, Giorgio; Landini, Ettore; Caviglia, Claudia; Heiskanen, Arto; Comminges, Clément; Zór, Kinga; Sabourin, David; Dufva, Martin; Dimaki, Maria; Raiteri, Roberto; Wollenberger, Ulla; Emneus, Jenny; Sampietro, Marco

2012-10-01

322

A thin layer electrochemical cell for disinfection of water contaminated with Staphylococcus aureus  

PubMed Central

A thin layer electrochemical cell was tested and developed for disinfection treatment of water artificially contaminated with Staphylococcus aureus. Electrolysis was performed with a low-voltage DC power source applying current densities of 75 mA cm-2 (3 A) or 25 mA cm-2 (1 A). A dimensionally stable anode (DSA) of titanium coated with an oxide layer of 70%TiO2 plus 30%RuO2 (w/w) and a 3 mm from a stainless-steel 304 cathode was used in the thin layer cell. The experiments were carried out using a bacteria suspension containing 0.08 M sodium sulphate with chloride-free to determine the bacterial inactivation efficacy of the thin layer cell without the generation of chlorine. The chlorine can promote the formation of trihalomethanes (THM) that are carcinogenic. S. aureus inactivation increased with electrolysis time and lower flow rate. The flow rates used were 200 or 500 L h-1. At 500 L h-1 and 75 mA cm-2 the inactivation after 60 min was about three logs of decreasing for colony forming units by mL. However, 100% inactivation for S. aureus was observed at 5.6 V and 75 mA cm-2 after 30 min. Thus, significant disinfection levels can be achieved without adding oxidant substances or generation of chlorine in the water. PMID:24031410

Gusmao, Isabel C. P.; Moraes, Peterson B.; Bidoia, Ederio D.

2009-01-01

323

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

PubMed

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

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

2012-01-01

324

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

PubMed Central

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

Williams, Matthew A.

2014-01-01

325

Peroxiredoxin II Regulates Effector and Secondary Memory CD8+ T Cell Responses  

PubMed Central

Reactive oxygen intermediates (ROI) generated in response to receptor stimulation play an important role in cellular responses. However, the effect of increased H2O2 on an antigen-specific CD8+ T cell response was unknown. Following T cell receptor (TCR) stimulation, the expression and oxidation of peroxiredoxin II (PrdxII), a critical antioxidant enzyme, increased in CD8+ T cells. Deletion of PrdxII increased ROI, S phase entry, division, and death during in vitro division. During primary acute viral and bacterial infection, the number of effector CD8+ T cells in PrdxII-deficient mice was increased, while the number of memory cells were similar to those of the wild-type cells. Adoptive transfer of P14 TCR transgenic cells demonstrated that the increased expansion of effector cells was T cell autonomous. After rechallenge, effector CD8+ T cells in mutant animals were more skewed to memory phenotype than cells from wild-type mice, resulting in a larger secondary memory CD8+ T cell pool. During chronic viral infection, increased antigen-specific CD8+ T cells accumulated in the spleens of PrdxII mutant mice, causing mortality. These results demonstrate that PrdxII controls effector CD8+ T cell expansion, secondary memory generation, and immunopathology. PMID:23055551

Michalek, Ryan D.; Crump, Katie E.; Weant, Ashley E.; Hiltbold, Elizabeth M.; Juneau, Daniel G.; Moon, Eun-Yi; Yu, Dae-Yeul; Poole, Leslie B.

2012-01-01

326

Electrochemical photovoltaic cells/stabilization and optimization of II-VI semiconductors. Final technical report  

SciTech Connect

The overall goal of this program is to provide the basis for designing a practical electrochemical solar cell based on the II-VI compound semiconductors. Emphasis is on developing new electrolyte redox sytems and electrode surface modifications which will stabilize the II-VI compounds against photodissolution without seriously degrading the long-term solar response. The bulk electrode material properties are also being optimized to provide the maximum solar conversion efficiency and greatest inherent electrode stability. Stabilization of n-CdSe against photodissolution has been achieved for the methanol/tetraethylammonium ferro-ferricyanide system. No degradation of the photocurrent or the electrode surface, even in the presence of traces of water, has been observed for runs up to 700 h at 6 mA/cm/sup 2/ and approx. AM1 light intensity. With higher quality single crystal CdSe, stable sort-circuit photocurrents of 15 to 17 mA/cm/sup 2/ and an open circuit voltage of 0.7 V (tungsten-halogen illumination) have been obtained, corresponding to a conversion efficiency of about 5%. Preliminary evaluation of a series of sulfur-containing 1,2-dithiolene metal complexes for stabilization of CdX photoanodes in acetonitrile solution has been completed. For the first time, a conducting polymer film (derived from pyrrole) has been electrochemically deposited on a semiconductor electrode. This could represent a breakthrough in the use of hydrophobic films to protect semiconductor photoanodes from dissolution/degradation. Mixed CdSe-CdTe solid solution electrodes were found to exhibit a minimum in both the flatband potential and the bandgap at approx. 65% CdTe. Both of these shifts would have a detrimental effect on the solar conversion efficiency.

Noufi, R.; Tench, D.; Warren, L.

1980-05-01

327

Evaluation program for secondary spacecraft cells: Cycle life test  

NASA Technical Reports Server (NTRS)

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.

Harkness, J. D.

1979-01-01

328

Cross-flow electrochemical reactor cells, cross-flow reactors, and use of cross-flow reactors for oxidation reactions  

DOEpatents

This invention discloses cross-flow electrochemical reactor cells containing oxygen permeable materials which have both electron conductivity and oxygen ion conductivity, cross-flow reactors, and electrochemical processes using cross-flow reactor cells having oxygen permeable monolithic cores to control and facilitate transport of oxygen from an oxygen-containing gas stream to oxidation reactions of organic compounds in another gas stream. These cross-flow electrochemical reactors comprise a hollow ceramic blade positioned across a gas stream flow or a stack of crossed hollow ceramic blades containing a channel or channels for flow of gas streams. Each channel has at least one channel wall disposed between a channel and a portion of an outer surface of the ceramic blade, or a common wall with adjacent blades in a stack comprising a gas-impervious mixed metal oxide material of a perovskite structure having electron conductivity and oxygen ion conductivity. The invention includes reactors comprising first and second zones seprated by gas-impervious mixed metal oxide material material having electron conductivity and oxygen ion conductivity. Prefered gas-impervious materials comprise at least one mixed metal oxide having a perovskite structure or perovskite-like structure. The invention includes, also, oxidation processes controlled by using these electrochemical reactors, and these reactions do not require an external source of electrical potential or any external electric circuit for oxidation to proceed.

Balachandran, Uthamalingam (Hinsdale, IL); Poeppel, Roger B. (Glen Ellyn, IL); Kleefisch, Mark S. (Naperville, IL); Kobylinski, Thaddeus P. (Lisle, IL); Udovich, Carl A. (Joliet, IL)

1994-01-01

329

Triphenylamine-based organic dyes with julolidine as the secondary electron donor for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Two novel donor-donor-?-conjugated-acceptor (D-D-?-A) metal-free organic dyes (JTPA1 and JTPA2) with a julolidine moiety as the secondary electron donor for dye-sensitized solar cells (DSSCs) are synthesized. Their absorption spectra, electrochemical and photovoltaic properties are extensively investigated and compared with TPA2 dye. Transient absorption measurements show that both sensitizers are quickly regenerated and the dye cations are efficiently intercepted by the redox mediator. Both dyes show good performance as DSSC photosensitizers. In particular, a DSSC using JTPA2 with rhodanine-3-acetic acid shows better photovoltaic performance with a short-circuit photocurrent density (Jsc) of 9.30 mA cm-2, an open-circuit photovoltage (Voc) of 509 mV and a fill factor (FF) of 0.68, corresponding to an overall conversion efficiency (?) of 3.2% under AM 1.5 irradiation (100 mW cm-2). Under similar test conditions, ruthenium-based N719 dye gives an efficiency of 6.7%. Compared to TPA2, the dye regeneration rate, the short-circuit photocurrent density and the conversion efficiency of JTPA2 are doubled by introducing a julolidine unit. Our findings show that the julolidine unit may be an excellent electron donor system for organic dyes harvesting solar irradiation.

Wu, Guohua; Kong, Fantai; Li, Jingzhe; Fang, Xiaqin; Li, Yi; Dai, Songyuan; Chen, Qianqian; Zhang, Xianxi

2013-12-01

330

Relation between primary and secondary metabolism in plant cell suspensions  

Microsoft Academic Search

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.

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

1995-01-01

331

Hermetically sealed electrical feedthrough for high temperature secondary cells  

DOEpatents

A passthrough seal is disclosed for electrically isolating the terminal in a lithium/metal sulfide cell from the structural cell housing. The seal has spaced upper and lower insulator rings fitted snuggly between the terminal and an annularly disposed upstanding wall, and outwardly of a powdered insulator also confined between the upstanding wall and terminal. The adjacent surfaces of the upper insulator ring and the respective upstanding wall and terminal are conically tapered, diverging in the axial direction away from the cell interior, and a sealing ring is located between each pair of the adjacent surfaces. The components are sized so that upon appropriate movement of the upper insulator ring toward the lower insulator ring the powdered insulator and sealing rings are each compressed to a high degree. This compacts the powdered insulator thereby rendering the same highly impervious and moreover fuses the sealing rings to and between the adjacent surfaces. The upper and lower insulator rings might be formed of beryllium oxide and/or alumina, the powdered insulator might be formed of boron nitride, and the sealing rings might be formed of aluminum.

Knoedler, R.; Nelson, P.A.; Shimotake, H.; Battles, J.E.

1983-07-26

332

Microfluidic platform for the evaluation of multi-glycan expressions on living cells using electrochemical impedance spectroscopy and optical microscope.  

PubMed

A microfluidic platform to evaluate the expression of multi-glycans on a cell surface was developed using electrochemical impedance spectroscopy (EIS) and optical microscope technique. In the microfluidic channel, four indium tin oxide (ITO) electrodes were modified with three lectins and one passivation agent, respectively, to selectively recognize the corresponding carbohydrate epitopes on the cell surface. The binding of the cells on the electrode array was monitored by the electrochemical impedance to evaluate the expression of cell surface glycans. The excellent optical transparency of ITO electrode permitted the microscopic observation of the cell binding simultaneously to substantiate the impedance measurement. Compared with the individual technology, the double-check mode increased the sensitivity and accuracy of the assay. The experimental results using these two techniques indicated that the cell binding ability decreased in the order WGA > Con A > PNA, which was consistent with the expression difference of carbohydrate epitopes on K562 cell surface. The proposed strategy was further used for facile evaluating the variations of glycan expression on living cells in response to drugs. The consumption of cell sample for each sensing interface in the whole experiments is merely 5 × 10(3) cells. This platform offers great promise for cancer-associated glycol-biomarkers screening and further helps cancer diagnosis and treatment. PMID:22834410

Cao, Jun-Tao; Hao, Xiao-Yao; Zhu, Ying-Di; Sun, Ken; Zhu, Jun-Jie

2012-08-01

333

The toughness of secondary cell wall and woody tissue  

PubMed Central

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.

Lucas, P. W.; Tan, H. T. W.; Cheng, P. Y.

1997-01-01

334

Application of electrochemical deposition techniques to thin film solar cell processing  

NASA Astrophysics Data System (ADS)

During the last eight years the manufacturing volume of thin film modules has grown at a compounded annualized rate of over 90%. Today the share of thin film products in the global photovoltaics (PV) market is in the range of 10-15%. Considering the fact that wafer Si technologies have achieved impressive cost reductions during the last few years, any increase in thin film market share during the next decade will require these technologies to aggressively drive for cost reductions through device efficiency improvements and utilization of lower cost manufacturing techniques. Electrochemical deposition or electrodeposition is an attractive low cost approach for the formation of thin film coatings. Such coatings have already found large scale applications in circuit board fabrication and integrated circuit manufacturing. In these applications, the electroplated layers are mainly used as passive components that carry electrical current. Application of electrodeposition techniques to thin film solar cell fabrication involves formation of semiconductor absorber layers that actively participate in power generation. This requirement brings along certain challenges that need to be overcome. In this paper we will present a review of work carried out for the application of electrodeposition techniques to the fabrication of CdTe and CIGS based solar cells and modules.

Ba?ol, Bülent M.

2011-09-01

335

Deformation and failure mechanism of secondary cell wall in Spruce late wood  

NASA Astrophysics Data System (ADS)

The deformation and failure of the secondary cell wall of Spruce wood was studied by in-situ SEM compression of micropillars machined by the focused ion beam technique. The cell wall exhibited yield strength values of approximately 160 MPa and large scale plasticity. High resolution SEM imaging post compression revealed bulging of the pillars followed by shear failure. With additional aid of cross-sectional analysis of the micropillars post compression, a model for deformation and failure mechanism of the cell wall has been proposed. The cell wall consists of oriented cellulose microfibrils with high aspect ratio embedded in a hemicellulose-lignin matrix. The deformation of the secondary wall occurs by asymmetric out of plane bulging because of buckling of the microfibrils. Failure of the cell wall following the deformation occurs by the formation of a shear or kink band.

Adusumalli, Ramesh-Babu; Raghavan, Rejin; Ghisleni, Rudy; Zimmermann, Tanja; Michler, Johann

2010-08-01

336

Electrochemical detection of catecholamine exocytosis using planar iridium oxide electrodes in nanoliter microfluidic cell culture volumes  

PubMed Central

Release of neurotransmitters and hormones by Ca2+ regulated exocytosis is a fundamental cellular/molecular process that is disrupted in a variety of psychiatric, neurological, and endocrine disorders. Therefore, this area represents a relevant target for drug and therapeutic development, efforts that will be aided by novel analytical tools and devices that provide mechanistically rich data with increased throughput. Toward this goal, we have electrochemically deposited iridium oxide (IrOx) films onto planar thin film platinum electrodes (20×300µm2) and utilized these for quantitative detection of catecholamine exocytosis from adrenal chromaffin cells trapped in a microfluidic network. The IrOx electrodes show a linear response to norepinephrine in the range of 0–400µM, with a sensitivity of 23.1±0.5mA/(M·mm2). The sensitivity of the IrOx electrodes does not change in the presence of ascorbic acid, a substance commonly found in biological samples. A replica molded polydimethylsiloxane (PDMS) microfluidic device with nanoliter sensing volumes was aligned and sealed to a glass substrate with the sensing electrodes. Small populations of chromaffin cells were trapped in the microfluidic sensing chamber and stimulated by rapid perfusion with high potassium (50mM) containing Tyrode’s solution at a flow rate of 1nL/s. Stimulation of the cells produced a rapid increase in current due to oxidation of the released catecholamines, with an estimated maximum concentration in the microfluidic device ~52µM. Thus, we demonstrate the utility of an integrated microfluidic network with IrOx electrodes for real-time quantitative detection of catecholamines released from small populations of cells. PMID:22398270

Ges, Igor A.; Currie, Kevin P.M.; Baudenbacher, Franz

2013-01-01

337

Comprehensive forensic analyses of debris from the fatal explosion of a "cold fusion" electrochemical cell.  

PubMed

Selected components of explosion debris from the SRI International incident of January 2, 1992 were subjected to forensic analyses to elucidate potential causes of, or contributing factors to, the explosion. Interrogation of the debris encompassed nuclear, chemical, physical, and materials investigations. Nuclear studies for the determination of tritium and neutron-activation products in stainless steel and brass were conducted. No evidence for signature species indicative of orthodox nuclear events was detected. The inorganic and particulate analyses were likewise negative with respect to residues of unexpected chemical species. Such target compounds included conventional explosives, accelerants, propellants, or any exceptional industrial chemicals. Materials characterization identified the type of stainless steel used in the manufacture of the electrolytic cell as one relatively high in Mo concentration, probably type 316. Metallurgical analyses of the cell vessel wall and its detached base provided no evidence of corrosion or hydrogen embrittlement, leaving only ductile failure of the weld as contributing to the incident. The weld was found to have missed the center-line of the step joint, and the average penetration of the weld was measured to be 54%. The GC-MS analyses of trace organic components in the explosion debris provided a most interesting result. Although no evidence of organic explosives, oxidizers, or other unusual compounds was detected, the presence of an organic oil in the interior of the electrochemical cell was established. It is likely that the source of this oil was lubricating fluid from machining the metal cell components.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7876799

Grant, P M; Whipple, R E; Andresen, B D

1995-01-01

338

A novel quantum dot nanocluster as versatile probe for electrochemiluminescence and electrochemical assays of DNA and cancer cells.  

PubMed

A novel dendritic quantum dot (QD) nanocluster was constructed and used as versatile electrochemiluminescence (ECL) and electrochemical probe for the detection of DNA and cancer cells. Owing to the many functional groups present in the nanoclusters, a large number of QDs were assembled on the nanoclusters, which could greatly amplify both the ECL and electrochemical signals of QDs. Carbon nanotubes (CNTs)/gold nanoparticles' (NPs) hybrids were used as amplified platform for assembling large numbers of DNA on the electrode, which also improve the bioactivity and stability of the electrode. After the QD-DNA signal probe was recognized with target DNA (t-DNA), the amplified ECL signal for the detection of target DNA was obtained. Furthermore, magnetic nanoparticles were employed for cell aptamers immobilization, the same QD nanocluster-DNA probe was also extended for electrochemical detection of cancer cells using sensitive anodic stripping voltammetry (ASV) method, which simplified the separation procedures and improved the sensitivity. It is anticipated that the assays could provide promising and cost effective approach for the early and accurate detection of DNA and cancer cells. PMID:24021658

Jie, Guifen; Zhang, Jian; Jie, Guixia; Wang, Lei

2014-02-15

339

Measuring fundamental properties in operating solid oxide electrochemical cells by using in situ X-ray photoelectron spectroscopy.  

PubMed

Photoelectron spectroscopic measurements have the potential to provide detailed mechanistic insight by resolving chemical states, electrochemically active regions and local potentials or potential losses in operating solid oxide electrochemical cells (SOCs), such as fuel cells. However, high-vacuum requirements have limited X-ray photoelectron spectroscopy (XPS) analysis of electrochemical cells to ex situ investigations. Using a combination of ambient-pressure XPS and CeO(2-x)/YSZ/Pt single-chamber cells, we carry out in situ spectroscopy to probe oxidation states of all exposed surfaces in operational SOCs at 750 °C in 1 mbar reactant gases H(2) and H(2)O. Kinetic energy shifts of core-level photoelectron spectra provide a direct measure of the local surface potentials and a basis for calculating local overpotentials across exposed interfaces. The mixed ionic/electronic conducting CeO(2-x) electrodes undergo Ce(3+)/Ce(4+) oxidation-reduction changes with applied bias. The simultaneous measurements of local surface Ce oxidation states and electric potentials reveal the active ceria regions during H(2) electro-oxidation and H(2)O electrolysis. The active regions extend ~150 ?m from the current collectors and are not limited by the three-phase-boundary interfaces associated with other SOC materials. The persistence of the Ce(3+)/Ce(4+) shifts in the ~150 ?m active region suggests that the surface reaction kinetics and lateral electron transport on the thin ceria electrodes are co-limiting processes. PMID:20871607

Zhang, Chunjuan; Grass, Michael E; McDaniel, Anthony H; DeCaluwe, Steven C; El Gabaly, Farid; Liu, Zhi; McCarty, Kevin F; Farrow, Roger L; Linne, Mark A; Hussain, Zahid; Jackson, Gregory S; Bluhm, Hendrik; Eichhorn, Bryan W

2010-11-01

340

Ceramic processing and electrochemical analysis of proton conductive solid oxide fuel cell  

NASA Astrophysics Data System (ADS)

Ba(Zr0.8-xCexY0.2)O3-delta (0?x?0.4) (BZCYs) powders were successfully fabricated by both solid state reaction and glycine-nitrate process. Lithium fluoride (LiF) was selected as a liquid phase sintering additive to lower the sintering temperature of BZCYs. Using LiF as an additive, high density BZCYs ceramics can be obtained at sintering temperatures 200˜300 °C lower than the usual 1700 °C with much shorter soaking time. Nuclear reaction investigations showed no lithium and a small amount of fluorine reside in the sample which indicates the non-concomitant evaporation of lithium and fluorine during the sintering process. Scanning electron microscopic investigations showed the bimodal structure of BZCY ceramics and grain growth as Ce content increases. In a water saturated hydrogen containing atmosphere, BZCY ceramics have higher conductivity when LiF is used in the sintering process. LiF-added BZCY electrolyte-supported fuel cells with different cathodes were tested at temperatures from 500˜850 °C. Results show that Pt cathode gives much higher power output than ceramic cathodes, indicating much larger polarization from ceramic cathodes than Pt. Ba(Zr0.6Ce 0.2Y0.2)O3-delta anode supported proton conductive solid oxide fuel cells (H-SOFCs) show low power output due to its low proton conductivity. Ba(Ce0.8Y0.2)O3-delta anode supported H-SOFCs show excellent power output. Different H2 and O2 partial pressures were used for fuel and oxidative gas, respectively, to obtain information for V(i) modeling. Different thicknesses of supporting anode were used to obtain saturation current densities of H-SOFC. Using the dusty-gas model which includes Stefan-Maxwell equation and Knudsen terms, the calculation gave tortuosity of our supporting anode 1.95+/-0.1. The gas concentrations across the anode were also calculated by knowing the tortuosity of the supporting anode. An electrochemical model of H-SOFC was developed. The excellent agreement between model and experimental data implies that our model is close to the true physical picture of H-SOFC. The more accurate prediction of our model, based on a physical picture of electrochemical processes, also provides a replacement for using the Butler-Volmer equation in SOFC modeling. In the parametric analysis, our model shows that ohmic polarization and cathodic polarization limit the performance of H-SOFC. Research for improving H-SOFC performance should be focused on reducing electrolyte thickness, increasing proton conductivity of electrolyte and finding a compatible cathode material.

Tsai, Chih-Long

341

Electrochemical methane sensor  

DOEpatents

A method and instrument including an electrochemical cell for the detection and measurement of methane in a gas by the oxidation of methane electrochemically at a working electrode in a nonaqueous electrolyte at a voltage about 1.4 volts vs R.H.E. (the reversible hydrogen electrode potential in the same electrolyte), and the measurement of the electrical signal resulting from the electrochemical oxidation.

Zaromb, S.; Otagawa, T.; Stetter, J.R.

1984-08-27

342

Cell design for in situ x-ray scattering studies of metal\\/solution interfaces under electrochemical control  

Microsoft Academic Search

During the last decade, there has been an increasing use of synchrotron x-ray techniques for the insitu investigation of the structure and composition of metal\\/solution interfaces under electrochemical control. While a number of experimental cell designs have been utilized in the past, every one of them has exhibited some shortcomings. This paper describes the development of a wide-angle-accessible, transmission-geometry, sandwich-type,

Z. Nagy; H. You; R. M. Yonco

1994-01-01

343

Process for manufacture of positive electrode for lithium\\/metal sulfide secondary cell  

Microsoft Academic Search

An electrode for a high temperature secondary electrical storage cell including an alkali metal negative electrode, a molten salt electrolyte, and a transition metal sulfide as the positive electrode, formed by mechanically loading a precut form or graphite felt or foam with fesx powder, coating or impregnating the precut form with a high carbon yield resin, curing the resin at

L. A. Joo; F. C. Miller

1980-01-01

344

A scanning electron microscopic study of secondary lamellae and chloride cells of rainbow trout ( Salmo gairdneri )  

Microsoft Academic Search

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

Kenneth R. Olson; Paul O. Fromm

1973-01-01

345

Graviresponsiveness and columella cell structure in primary and secondary roots of Ricinus communis  

Microsoft Academic Search

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

Randy Moore; John Pasieniuk

1984-01-01

346

CELL PHONES IN NEW ZEALAND SECONDARY SCHOOLS: BOON, BANNED OR BIASED  

Microsoft Academic Search

In this qualitative research study conducted in twelve New Zealand secondary schools data was gathered on policy formation on a range of issues including: cell phone usage at school; mobile technology incorporated into learning; staff development; curriculum development; assessment, school and class management; and registration and enrolment. Participants included: school principals; deans; heads of department; guidance officers; teachers; and prior

K. FIELDEN; P. MALCOLM

2007-01-01

347

Homeostatic chemokines guide lymphoma cells to tumor growth-promoting niches within secondary lymphoid organs.  

PubMed

The interaction between lymphoid tumor cells and their tissue microenvironment is thought to promote dissemination and progression of lymphoma. Those type of interactions consists of at least three cornerstones, among them mesenchymal- or bone marrow-derived stromal cells, cells of the innate or adaptive immune response, and the lymphoma cells themselves. The molecular pathways of crosstalk between the lymphoma cells and their nursing stroma are not well understood and their dissection is challenging because of (1) the complexity of stroma cell subpopulations, (2) kinetic and developmental transitions/switches of stroma composition, and (3) inherent technical difficulties to isolate and analyze defined stroma cell subsets. However, recent studies of bone marrow stroma interaction with leukemia or lymphoma cells have revealed therapeutic targets involved in regulating tumor cell mobilization. Release of tumor cells from their supportive niches could be effectuated by inhibition of homing and retention signals. The present review focuses on the effects of homing receptors and cytokines attributed to lymphoid tissue formation in tumor-stroma interactions within secondary lymphoid tissues. We discuss possible cellular and molecular mechanisms of lymphoma-stroma crosstalk and highlight novel therapeutic strategies based on the disruption of tumor-stroma interaction in secondary lymphoid organs. PMID:22577036

Höpken, Uta E; Rehm, Armin

2012-11-01

348

Renal Cell Carcinoma presenting as small bowel obstruction secondary to a metastatic ileal intussusception  

PubMed Central

We report a rare clinical presentation of renal cell carcinoma in the form of small bowel obstruction which was secondary to a metastatic ileal intussusception. Intussusception in the elderly is most commonly due to an underlying neoplasm, however metastases from a renal cell carcinoma is very uncommon. We present clinical details, radiological and pathological findings of the case followed by a discussion of the diagnosis and management of intussusception in the adult population. PMID:24967032

Hegde, Rahul G; Gowda, Harish K; Agrawal, Rachana D; Yadav, Vikas K; Khadse, Gopal J

2014-01-01

349

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

DOEpatents

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.

Bowker, J.C.; Singh, P.

1989-08-29

350

Acetaminophen degradation by electro-Fenton and photoelectro-Fenton using a double cathode electrochemical cell.  

PubMed

Acetaminophen is a widely used drug worldwide and is one of the most frequently detected in bodies of water making it a high priority trace pollutant. This study investigated the applicability of the electro-Fenton and photoelectro-Fenton processes using a double cathode electrochemical cell in the treatment of acetaminophen containing wastewater. The Box-Behnken design was used to determine the effects of initial Fe(2+) and H(2)O(2) concentrations and applied current density. Results showed that all parameters positively affected the degradation efficiency of acetaminophen with the initial Fe(2+) concentration being the most significant parameter for both processes. The acetaminophen removal efficiency for electro-Fenton was 98% and chemical oxygen demand (COD) removal of 43% while a 97% acetaminophen removal and 42% COD removal were observed for the photoelectro-Fenton method operated at optimum conditions. The electro-Fenton process was only able to obtain 19% total organic carbon (TOC) removal while the photoelectro-Fenton process obtained 20%. Due to negligible difference between the treatment efficiencies of the two processes, the electro-Fenton method was proven to be more economically advantageous. The models obtained from the study were applicable to a wide range of acetaminophen concentrations and can be used in scale-ups. Thirteen different types of intermediates were identified and a degradation pathway was proposed. PMID:22480705

de Luna, Mark Daniel G; Veciana, Mersabel L; Su, Chia-Chi; Lu, Ming-Chun

2012-05-30

351

Investigation of dye regeneration kinetics in sensitized solar cells by scanning electrochemical microscopy.  

PubMed

Sensitizers are responsible for the light harvesting and the charge injection in dye-sensitized solar cells (DSSCs). A fast dye-regeneration process is necessary to obtain highly efficient DSSC devices. Herein, dye-regeneration rates of two DSSC device types, that is, the reduction of immediately formed photo-oxidized sensitizers (ruthenium complex C106TBA and porphyrin LD14, k(ox)') by iodide ions (I(-)) and [Co(bpy)3](2+), and the oxidation of formed photo-reduced sensitizers (organic dye P1, k(re)') by triiodide ions (I3(-)) and the disulfide dimer (T2) are investigated by scanning electrochemical microscopy (SECM). We provide a thorough experimental verification of the feedback mode to compare the kinetics for dye-regeneration by using the above mentioned mediators. The charge recombination at the dye/semiconductor/electrolyte interface is further investigated by SECM. A theoretical model is applied to interpret the current response at the tip under short-circuit conditions, providing important information on factors that govern the dynamics of dye-regeneration onto the dye-sensitized heterojunction. PMID:24729527

Zhang, Bingyan; Xu, Xiaobao; Zhang, Xiaofan; Huang, Dekang; Li, Shaohui; Zhang, Yibo; Zhan, Fang; Deng, Mingzhang; He, Yahui; Chen, Wei; Shen, Yan; Wang, Mingkui

2014-04-14

352

In-flight comparison of Brewer-Mast and electrochemical concentration cell ozonesondes  

NASA Astrophysics Data System (ADS)

The analysis of 140 dual flights between two types of ozonesondes, namely, the Brewer-Mast (BM) and the electrochemical concentration cell (ECC), is presented in this study. These dual flights were performed before the transition from BM to ECC as the operational ozonesonde for the Payerne Aerological Station, Switzerland. The different factors of the ozonesonde data processing are considered and their influences on the profile of the difference are evaluated. The analysis of the ozone difference between the BM and the ECC ozonesonde data shows good agreement between the two sonde types. The profile of the ozone difference is limited to ±5% (±0.3 mPa) from the ground to 32 km. The analysis confirms the appropriateness of the standard BM data processing method and the usefulness of the normalization of the ozonesonde data. The conclusions of the extended dual flight campaigns are corroborated by the analysis of the time series of the Payerne soundings for the periods of 5 years before and after the change from BM to ECC which occurred in September 2002. No significant discontinuity can be identified in 2002 attributable to the change of sonde.

Stübi, René; Levrat, Gilbert; Hoegger, Bruno; Viatte, Pierre; Staehelin, Johannes; Schmidlin, F. J.

2008-07-01

353

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

DOEpatents

A dense, electronically conductive interconnection layer 26 is bonded onto a porous, tubular, electronically conductive air electrode structure 16, optionally supported by a ceramic support 22, by (A) providing an air electrode surface, (B) forming on a selected portion of the electrode surface 24, 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.degree. C. to 1,550.degree. C., without the application of pressure, to provide a dense, sintered, interconnection material 26 bonded to the air electrode 16, where calcium and chromium from the surface deposit are incorporated into the structure of the LaCrO.sub.3. 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.

Bowker, Jeffrey C. (Richland Township, Allegheny County, PA); Singh, Prabhakar (Pittsburgh, PA)

1989-01-01

354

Electrochemical Characterization of Hydrothermally Synthesized Pt-Ru-Ni-P Catalyst for Direct Methanol Fuel Cell  

NASA Astrophysics Data System (ADS)

Pt-Ru-Ni-P/multiwalled carbon nanotube (MWCNT) catalyst is synthesized by a hydrothermal process using sodium hypophosphite (NaH2PO2) as a reducing agent. The particle size is evaluated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The electrocatalytic activity of a Pt-Ru-Ni-P/MWCNT catalyst for methanol electro-oxidation has been studied by cyclic voltammetry, chromoamperometry, and impedance spectroscopy. TEM images reveal that the Pt-Ru-Ni-P nanoparticles have a wide size distribution with an average size of 3.2 nm. Pt-Ru-Ni-P/MWCNT catalyst shows an electrochemically active surface area of 63.2 m2 g-1 and a mass activity of 187.56 mA mg Pt-1. It has been found that the presence of phosphorus as an interstitial species can enhance the dispersion as well as reduce the size of Pt-Ru-Ni-P nanoparticles. Moreover, incorporation of phosphorus into the Pt-Ru-Ni/MWCNT catalyst shows a 1.5 times higher electrocatalytic activity. The power density (57 mW cm-1) of the Pt-Ru-Ni-P/MWCNT catalyst in fuel cell tests is higher than that (40 mW cm-1) of the Pt-Ru-Ni/MWCNT catalyst.

Lee, Seok-Hee; Kim, Dong-Joo; Yoon, Young-Soo

2013-03-01

355

White light-emitting electrochemical cells based on the langmuir-blodgett technique.  

PubMed

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

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

356

Electrochemical photovoltaic cells II-VI compound thin film electrodes. Annual report, June 1980-June 1981  

SciTech Connect

This year's program has focused on developing stable, thin film II-VI compound electrodes with sunlight efficiencies of 10%, for use with aqueous polysulfide electrolyte in frontwall and backwall illuminated electrochemical photovoltaic cells. The main effort has been directed towards establishing the relationships among processing of the thin films, resultant electronic properties, and I-V performance in order to produce electrodes with maximum power conversion efficiency. The efficiency of n-CdSe electrodes deposited on titanium substrates has been improved from between 3 to 5% to 5.5% to 6.5% by refinement of the thin film processing parameters as well as electrode surface treatment with ZnCl/sub 2/ solution. The efficiency of n-CdSe electrodes deposited on tin oxide coated glass has been improved from between 3 to 4% to the range of 6 to 6.5% due to modifications of the electrode geometry dictated by a photon loss minimization, and to electrode etching treatment.

Russak, M.A.; Reichman, J.; DeCarlo, J.; Creter, C.

1981-07-01

357

Secondary Philadelphia chromosome and erythrophagocytosis in a relapsed acute myeloid leukemia after hematopoietic cell transplantation.  

PubMed

The acquisition of the Philadelphia chromosome (Ph) as a secondary change during the course of hematopoietic malignancies is rare and is associated with poor prognosis. Few cases of secondary Ph have been reported after hematopoietic cell transplantation (HCT). A secondary Ph at relapse is of clinical importance because it provides a therapeutic target for tyrosine kinase inhibitors along with or in replacement of chemotherapy. We describe a case of relapsed acute myeloid leukemia (AML) after HCT that developed a BCR-ABL1 translocation along with erythrophagocytosis by blasts as a secondary change at the time of relapse. The progression of this patient's myeloid neoplasm from myelodysplastic syndrome to AML to relapsed AML after HCT was accompanied by a stepwise cytogenetic evolution: A deletion 20q abnormality subsequently acquired a deletion 7q and, finally, at relapse after HCT, a secondary Ph was gained. The relationship between the secondary Ph and the erythrophagocytosis by blasts is not clear. We review the possible pathogenesis and cytogenetic associations of erythrophagocytosis by blasts, a rare feature in acute leukemias. PMID:25074248

Kelemen, Katalin; Galani, Komal; Conley, Christopher R; Greipp, Patricia T

2014-06-01

358

Dengue Virus Activates Polyreactive, Natural IgG B Cells after Primary and Secondary Infection  

PubMed Central

Background Dengue virus is transmitted by mosquitoes and has four serotypes. Cross-protection to other serotypes lasting for a few months is observed following infection with one serotype. There is evidence that low-affinity T and/or B cells from primary infections contribute to the severe syndromes often associated with secondary dengue infections. such pronounced immune-mediated enhancement suggests a dengue-specific pattern of immune cell activation. This study investigates the acute and early convalescent B cell response leading to the generation of cross-reactive and neutralizing antibodies following dengue infection. Methodology/Principal Findings We assayed blood samples taken from dengue patients with primary or secondary infection during acute disease and convalescence and compared them to samples from patients presenting with non-dengue related fever. Dengue induced massive early plasmablast formation, which correlated with the appearance of polyclonal, cross-reactive IgG for both primary and secondary infection. Surprisingly, the contribution of IgG to the neutralizing titer 4–7 days after fever onset was more than 50% even after primary infection. Conclusions/Significance Poly-reactive and virus serotype cross-reactive IgG are an important component of the innate response in humans during both primary and secondary dengue infection, and “innate specificities” seem to constitute part of the adaptive response in dengue. While of potential importance for protection during secondary infection, cross-reactive B cells will also compete with highly neutralizing B cells and possibly interfere with their development. PMID:22216280

Toh, Ying Xiu; Flamand, Marie; Devi, Shamala; Koh, Mickey B.; Hibberd, Martin L.; Ooi, Eng Eong; Low, Jenny G.; Leo, Yee Sin; Gu, Feng; Fink, Katja

2011-01-01

359

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

PubMed Central

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

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

2011-01-01

360

Apoptotic cells subjected to cold/warming exposure disorganize apoptotic microtubule network and undergo secondary necrosis.  

PubMed

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

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

361

Fusion of bone marrow-derived cells with cancer cells: metastasis as a secondary disease in cancer  

PubMed Central

This perspective article highlights the leukocyte-cancer cell hybrid theory as a mechanism for cancer metastasis. Beginning from the first proposal of the theory more than a century ago and continuing today with the first proof for this theory in a human cancer, the hybrid theory offers a unifying explanation for metastasis. In this scenario, leukocyte fusion with a cancer cell is a secondary disease superimposed upon the early tumor, giving birth to a new, malignant cell with a leukocyte-cancer cell hybrid epigenome. PMID:24589183

Pawelek, John M.

2014-01-01

362

Electrochemical Filtering of CO from Fuel-Cell Reformate Balasubramanian Lakshmanan,a,  

E-print Network

Huang,b and John W. Weidnera, **,z a Center for Electrochemical Engineering, Department of Chemical the pulse profile e.g., on-time, off-time, pulse potential the CO and H2 oxidation currents were varied

Weidner, John W.

363

Novel Concepts in Electrochemical Solar Cells. Quarterly Technical Progress Report, December 15, 1980-March 15, 1981.  

National Technical Information Service (NTIS)

During the past quarter, the following areas were emphasized: (a) characterization of redox couples with very positive potentials in room-temperature AlCl sub 3 -BPC electrolytes and comparison of the electrochemical behavior of decamethyl ferrocene in th...

1981-01-01

364

Selective electrochemical etching of p-CdTe (for photovoltaic cells)  

Microsoft Academic Search

The electrochemical etching of p-CdTe is investigated. This etching is based on a method used previously for the selective etching of n-type Cd-chalcogenide semiconductors. It is shown that the electrochemical etching creates a dense pattern of submicron pits, and increases the reverse bias photocurrent of a Schottky barrier device, made up of single crystal p-CdTe and a polysulfide electrolyte typically

R. Tenne

1983-01-01

365

Low-temperature charging of lithium-ion cells part I: Electrochemical modeling and experimental investigation of degradation behavior  

NASA Astrophysics Data System (ADS)

Fast charge of Li-ion cells is one of the main challenges in automotive battery application. As a particular problem at low temperatures and high charging rates, lithium deposits as metal on the anode surface (so-called lithium plating) instead of intercalation. Electrochemical models help to understand internal processes and predict aging effects, which finally lead to optimized charging strategies. In this work, a 1D + 1D (pseudo-2D) electrochemical model is developed, applied over a wide range of temperature (T = -25 °C to 40 °C) and current (I = 0.1 C to 6 C), and coupled with a 0D thermal model. The model is parameterized with measurement data in frequency domain using electrochemical impedance spectroscopy (EIS) and validated with time-domain data. In experiments cells are charged under different operating conditions. Capacity fade is measured after a significant number of cycles and compared to the simulated anode potential. A qualitative correlation is found between the degradation in experiment and the anode potential dropping below 0 V vs. Li/Li+ at the separator-anode boundary in the simulation. Furthermore a semi-quantitative expression for degradation is introduced. The transformation of the model into an on-board applicable form is presented in the companion contribution (part II).

Tippmann, Simon; Walper, Daniel; Balboa, Luis; Spier, Bernd; Bessler, Wolfgang G.

2014-04-01

366

Electrochemical impedance spectroscopy of dye-sensitized solar cells with thermally degraded N719 loaded TiO2  

NASA Astrophysics Data System (ADS)

Here, we have deliberately degraded N719 loaded TiO2 photoelectrodes (PEs) at elevated temperatures; for example, from 80 °C to 160 °C with a step of 40 °C and studied their influence on photovoltaic parameters of dye-sensitized solar cells (DSSCs). Electrochemical impedance spectroscopy (EIS) study shows that the thermal degraded PEs suffered from increased recombination as well as downward shift of TiO2 conduction band that eventually decreased photovoltage of the cells. In contrast, incident photon-to-current efficiency (IPCE) reveals that poor light harvesting, charge collection and dye regeneration efficiency were responsible for low photocurrent of the DSSCs with thermal degraded PEs.

Sarker, Subrata; Seo, Hyun Woo; Kim, Dong Min

2013-10-01

367

Chemically and compositionally modified solid solution disordered multiphase nickel hydroxide positive electrode for alkaline rechargeable electrochemical cells  

DOEpatents

A high capacity, long cycle life positive electrode for use in an alkaline rechargeable electrochemical cell comprising: a solid solution nickel hydroxide material having a multiphase structure that comprises at least one polycrystalline .gamma.-phase including a polycrystalline .gamma.-phase unit cell comprising spacedly disposed plates with at least one chemical modifier incorporated around the plates, the plates having a range of stable intersheet distances corresponding to a 2.sup.+ oxidation state and a 3.5.sup.+, or greater, oxidation state; and at least one compositional modifier incorporated into the solid solution nickel hydroxide material to promote the multiphase structure.

Ovshinsky, Stanford R. (Bloomfield Hills, MI); Corrigan, Dennis (Troy, MI); Venkatesan, Srini (Southfield, MI); Young, Rosa (Troy, MI); Fierro, Christian (Troy, MI); Fetcenko, Michael A. (Rochester Hills, MI)

1994-01-01

368

Viral particles drive rapid differentiation of memory B cells into secondary plasma cells producing increased levels of antibodies.  

PubMed

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

Zabel, Franziska; Mohanan, Deepa; Bessa, Juliana; Link, Alexander; Fettelschoss, Antonia; Saudan, Philippe; Kündig, Thomas M; Bachmann, Martin F

2014-06-15

369

Secondary Cell Wall Deposition Causes Radial Growth of Fibre Cells in the Maturation Zone of Elongating Tall Fescue Leaf Blades  

PubMed Central

A gradient of development consisting of successive zones of cell division, cell elongation and cell maturation occurs along the longitudinal axis of elongating leaf blades of tall fescue (Festuca arundinacea Schreb.), a C3 grass. An increase in specific leaf weight (SLW; dry weight per unit leaf area) in the maturation region has been hypothesized to result from deposition of secondary cell walls in structural tissues. Our objective was to measure the transverse cell wall area (CWA) associated with the increase in SLW, which occurs following the cessation of leaf blade elongation at about 25 mm distal to the ligule. Digital image analysis of transverse sections at 5, 15, 45, 75 and 105 mm distal to the ligule was used to determine cell number, cell area and protoplast area of structural tissues, namely fibre bundles, mestome sheaths and xylem vessel elements, along the developmental gradient. Cell diameter, protoplast diameter and area, and cell wall thickness and area of fibre bundle cells were calculated from these data. CWA of structural tissues increased in sections up to 75 mm distal to the ligule, confirming the role of cell wall deposition in the increase in SLW (r2 = 0·924; P ? 0·01). However, protoplast diameter of fibre cells did not decrease significantly as CWA increased, although mean thickness of fibre cell walls increased by 95 % between 15 and 105 mm distal to the ligule. Therefore, secondary cell wall deposition in fibre bundles of tall fescue leaf blades resulted in continued radial expansion of fibre cells rather than in a decrease in protoplast diameter. PMID:12096823

MACADAM, JENNIFER W.; NELSON, CURTIS J.

2002-01-01

370

Promoting Effect of Layered Titanium Phosphate on the Electrochemical and Photovoltaic Performance of Dye-Sensitized Solar Cells  

NASA Astrophysics Data System (ADS)

We reported a composite electrolyte prepared by incorporating layered ?-titanium phosphate (?-TiP) into an iodide-based electrolyte using 1-ethyl-3-methylimidazolium tetrafluoroborate(EmimBF4) ionic liquid as solvent. The obtained composite electrolyte exhibited excellent electrochemical and photovoltaic properties compared to pure ionic liquid electrolyte. Both the diffusion coefficient of triiodide (I3 -) in the electrolyte and the charge-transfer reaction at the electrode/electrolyte interface were improved markedly. The mechanism for the enhanced electrochemical properties of the composite electrolyte was discussed. The highest conversion efficiency of dye-sensitized solar cell (DSSC) was obtained for the composite electrolyte containing 1wt% ?-TiP, with an improvement of 58% in the conversion efficiency than the blank one, which offered a broad prospect for the fabrication of stable DSSCs with a high conversion efficiency.

Cheng, Ping; Chen, Ruihao; Wang, Junfei; Yu, Jianong; Lan, Tian; Wang, Wanjun; Yang, Haijun; Wu, Haixia; Deng, Changsheng

2010-08-01

371

Promoting effect of layered titanium phosphate on the electrochemical and photovoltaic performance of dye-sensitized solar cells.  

PubMed

We reported a composite electrolyte prepared by incorporating layered ?-titanium phosphate (?-TiP) into an iodide-based electrolyte using 1-ethyl-3-methylimidazolium tetrafluoroborate(EmimBF4) ionic liquid as solvent. The obtained composite electrolyte exhibited excellent electrochemical and photovoltaic properties compared to pure ionic liquid electrolyte. Both the diffusion coefficient of triiodide (I3-) in the electrolyte and the charge-transfer reaction at the electrode/electrolyte interface were improved markedly. The mechanism for the enhanced electrochemical properties of the composite electrolyte was discussed. The highest conversion efficiency of dye-sensitized solar cell (DSSC) was obtained for the composite electrolyte containing 1wt% ?-TiP, with an improvement of 58% in the conversion efficiency than the blank one, which offered a broad prospect for the fabrication of stable DSSCs with a high conversion efficiency. PMID:20676195

Cheng, Ping; Chen, Ruihao; Wang, Junfei; Yu, Jianong; Lan, Tian; Wang, Wanjun; Yang, Haijun; Wu, Haixia; Deng, Changsheng

2010-01-01

372

Development of a standard bench-scale cell for electrochemical studies on inert anodes. Inert Anode/Cathode Program  

SciTech Connect

Objective of this work was to develop a standard bench-scale cell for performing short-term ac and dc polarization studies on inert anode candidate materials in molten cryolite. Two designs for electrochemical cells were developed and successfully evaluated in short-term experiments. Both cells consisted on the inert anode as a small cylindrical specimen partially sheathed in alumina, an Al/Al/sub 2/O/sub 3/ reference electrode, and a cryolite bath saturated in alumina. The difference between the two cells was in the design of the cathode. One cell used a bare solid metal cathode; the other used an aluminum pad similar to the Hall-Heroult configuration.

Windisch, C.F. Jr.; Boget, D.I.

1986-07-01

373

Characterization of high-power lithium-ion cells during constant current cycling. Part I. Cycle performance and electrochemical diagnostics  

NASA Astrophysics Data System (ADS)

Twelve cm 2 pouch type lithium-ion cells were assembled with graphite anodes, LiNi 0.8Co 0.15Al 0.05O 2 cathodes and 1 M LiPF 6/EC/DEC electrolyte. These pouch cells were cycled at different depths of discharge (100 and 70% DOD) at room temperature to investigate cycle performance and pulse power capability. The capacity loss and power fade of the cells cycled over 100% DOD was significantly faster than the cell cycled over 70% 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.

Shim, Joongpyo; Striebel, Kathryn A.

374

Gamma interferon response in secondary Leishmania major infection: role of CD8+ T cells.  

PubMed Central

CD8+ T cells have been shown to contribute to the rapid resolution of secondary lesions developing in immune mice challenged with Leishmania major. In the present study, we assessed directly the participation of specific CD8+ T cells in the memory response induced in immune mice by reinfection. Lymphocyte populations from reinfected immune mice exhibit marked secondary gamma interferon (IFN-gamma) responses. The participation of IFN-gamma-producing CD8+ T cells in the memory response elicited by secondary infectious challenge was demonstrated in both genetically resistant immune CBA mice and genetically susceptible immune BALB/c mice that were rendered resistant by administration of anti-CD4 monoclonal antibody in the early phase of the primary infection. The protective function of CD8+ T cells in experimental murine cutaneous leishmaniasis might thus be explained in part by their ability to secrete IFN-gamma. In this context, the neutralization of IFN-gamma at the time of reinfection reduced the Leishmania-specific delayed-type hypersensitivity response, showing that this cytokine is involved in the recall of immunological memory to L. major in vivo. PMID:8359894

Muller, I; Kropf, P; Etges, R J; Louis, J A

1993-01-01

375

Study of the electromotive force of electrochemical cell with polymeric membrane oriented in horizontal plane.  

PubMed

In order to characterize processes proceeded in concentration boundary layers (CBLs), divided by neutral and horizontally mounted membrane, the electromotive force (EMF) during and after turning off mechanical stirring of aqueous KCl solutions was measured. The EMF was measured by means of Ag / AgCl electrodes and electrometer connected with a microcomputer. Aqueous solutions of KCl with fixed and lower concentration Cl = 10(-5) mol x l(-1) was over the membrane, while KCl concentration under the membrane Ch > Cl was changed. Such configuration of membrane system caused stable reconstruction of CBLs after turning off mechanical stirring of solutions in electrochemical cell. On the basis of time dependencies of EMF the concentration dependencies were performed and it was stated that dependencies of EMF = f(Ch/Cl) are nonlinear. It was found that maximal value of EMF, equal to 175 mV, was observed during mechanical stirring of solutions for Ch/Cl = 400. In order to interpret experimental results, the model of EMF changes in time after turning off mechanical stirring was elaborated on the basis of Kedem-Katchalsky model equations for transport of electrolytes through the membrane. The transport number of K+ ions (t+), appointed for the membrane, depended nonlinearly on Ch/Cl and for Ch/Cl = 50 was maximal and amounted to t(+max) = 0.7. Besides, concentration dependence of relaxation time of CBLs reconstruction after turning off mechanical stirring was appointed. For Ch/Cl < 500, increase of Ch/Cl caused considerable decrease of relaxation time, while for Ch/Cl > 500 the relaxation time was small and did not change considerably with increase of Ch/Cl, in this range. PMID:17022156

Grzegorczyn, S?awomir; Slezak, Andrzej

2006-01-01

376

Electrochemical photovoltaic cells/stabilization and optimization of II-VI semiconductors  

SciTech Connect

The overall goal of this program is to provide the basis for designing a practical electrochemical solar cell based on the II-VI compound semiconductors. Emphasis is on developing new electrolyte redox systems and electrode surface modifications which will stabilize the II-VI compounds against photodissolution without seriously degrading the long-term solar response. 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 stabilizaton 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 photodecomposition 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 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.

Noufi, R.; Tench, D.; Warren, L.

1981-03-01

377

An AICDA-independent mechanism of secondary VH gene rearrangement in preimmune human B cells Running title: Secondary rearrangement in human B cells  

PubMed Central

VH replacement is a form of IgH chain receptor editing that is believed to be mediated by recombinase cleavage at cryptic recombination signals (cRSS) embedded in IGHV genes. Whereas there are several reports of IGHV replacement in primary and transformed human B cells and murine models, it remains unclear whether IGHV replacement contributes to the normal human B cell repertoire. We identified VH ? VHDJH compound rearrangements from fetal liver, fetal bone marrow and naive peripheral blood, all of which involved invading and recipient IGHV4 genes that contain a cryptic heptamer, 13 base pair (bp) spacer and nonamer in the 5' portion of framework region (FR) 3. Surprisingly, all pseudohybrid joins lacked molecular processing associated with typical VHDJH recombination or nonhomologous end joining. Although inefficient compared to a canonical RSS, the IGHV4 cRSS was a significantly better substrate for in vitro RAG-mediated cleavage than the IGHV3 cRSS. It has been suggested that activation induced cytidine deamination (AICDA) may contribute to VH replacement. However, we found similar secondary rearrangements utilizing IGHV4 genes in AICDA-deficient human B cells. The data suggest that IGHV4 replacement in preimmune human B cells is mediated by an AICDA-independent mechanism resulting from inefficient but selective RAG activity. PMID:19017972

Longo, Nancy S.; Grundy, Gabrielle J.; Lee, Jisoo; Gellert, Martin; Lipsky, Peter E.

2008-01-01

378

Room Temperature, Electrochemical Generation of Ozone with 50%?Current Efficiency in 0.5M Sulfuric Acid at Cell Voltages?  

Microsoft Academic Search

The electrochemical generation of ozone by Ni\\/Sb-SnO2 anodes immersed in 0.5M H2SO4 was assessed in both flow and recycle systems using the same electrochemical cell. The anodes were found to exhibit current efficiencies of up to 50%?for ozone generation under flow conditions at room temperature, with an optimum mole ratio in the precursor solutions of ca. 500:8:3 Sn:Sb:Ni and optimum

P. A. Christensen; W. F. Lin; H. Christensen; A. Imkum; J. M. Jin; G. Li; C. M. Dyson

2009-01-01

379

The role of the secondary cell wall in plant resistance to pathogens  

PubMed Central

Plant resistance to pathogens relies on a complex network of constitutive and inducible defensive barriers. The plant cell wall is one of the barriers that pathogens need to overcome to successfully colonize plant tissues. The traditional view of the plant cell wall as a passive barrier has evolved to a concept that considers the wall as a dynamic structure that regulates both constitutive and inducible defense mechanisms, and as a source of signaling molecules that trigger immune responses. The secondary cell walls of plants also represent a carbon-neutral feedstock (lignocellulosic biomass) for the production of biofuels and biomaterials. Therefore, engineering plants with improved secondary cell wall characteristics is an interesting strategy to ease the processing of lignocellulosic biomass in the biorefinery. However, modification of the integrity of the cell wall by impairment of proteins required for its biosynthesis or remodeling may impact the plants resistance to pathogens. This review summarizes our understanding of the role of the plant cell wall in pathogen resistance with a focus on the contribution of lignin to this biological process. PMID:25161657

Miedes, Eva; Vanholme, Ruben; Boerjan, Wout; Molina, Antonio

2014-01-01

380

Solid solution of nickel oxide and manganese oxide as negative active material for lithium secondary cells  

Microsoft Academic Search

The solid solution of nickel oxide and manganese oxide has been synthesized successfully by heating Ni1?aMnaOOH at a temperature ranging from 350 to 1000°C in oxygen atmosphere, and investigated as a high-capacity negative active material for lithium secondary cells. The discharge capacity of nickel and manganese oxide solid solution was decreased with increasing heat-treatment temperature. The average discharge potential shifts

Xingjiang Liu; Hideo Yasuda; Masanori Yamachi

2005-01-01

381

Regeneration of anion exchange resins by catalyzed electrochemical reduction  

DOEpatents

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.

Gu, Baohua (Oak Ridge, TN); Brown, Gilbert M. (Knoxville, TN)

2002-01-01

382

The overall structure of the human lens is one of succes-sive generations of secondary fiber cells stratified chrono-  

E-print Network

The overall structure of the human lens is one of succes- sive generations of secondary fiber cells fiber cells [1,3,4,11,12]. The lens must support the functionality of all of its constituent cells function of transporting water across cell membranes. Mutations in AQP0 have been shown to play a role

Hammock, Bruce D.

383

A novel approach for analyzing electrochemical properties of mixed conducting solid oxide fuel cell anode materials by impedance spectroscopy.  

PubMed

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 SrTi0.7Fe0.3O3-? (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

Nenning, A; Opitz, A K; Huber, T M; Fleig, J

2014-09-24

384

Mechanistic studies of water electrolysis and hydrogen electro-oxidation on high temperature ceria-based solid oxide electrochemical cells.  

PubMed

Through the use of ambient pressure X-ray photoelectron spectroscopy (APXPS) and a single-sided solid oxide electrochemical cell (SOC), we have studied the mechanism of electrocatalytic splitting of water (H2O + 2e(-) ? H2 + O(2-)) and electro-oxidation of hydrogen (H2 + O(2-) ? H2O + 2e(-)) at ?700 °C in 0.5 Torr of H2/H2O on ceria (CeO2-x) electrodes. The experiments reveal a transient build-up of surface intermediates (OH(-) and Ce(3+)) and show the separation of charge at the gas-solid interface exclusively in the electrochemically active region of the SOC. During water electrolysis on ceria, the increase in surface potentials of the adsorbed OH(-) and incorporated O(2-) differ by 0.25 eV in the active regions. For hydrogen electro-oxidation on ceria, the surface concentrations of OH(-) and O(2-) shift significantly from their equilibrium values. These data suggest that the same charge transfer step (H2O + Ce(3+) <-> Ce(4+) + OH(-) + H(•)) is rate limiting in both the forward (water electrolysis) and reverse (H2 electro-oxidation) reactions. This separation of potentials reflects an induced surface dipole layer on the ceria surface and represents the effective electrochemical double layer at a gas-solid interface. The in situ XPS data and DFT calculations show that the chemical origin of the OH(-)/O(2-) potential separation resides in the reduced polarization of the Ce-OH bond due to the increase of Ce(3+) on the electrode surface. These results provide a graphical illustration of the electrochemically driven surface charge transfer processes under relevant and nonultrahigh vacuum conditions. PMID:23822749

Zhang, Chunjuan; Yu, Yi; Grass, Michael E; Dejoie, Catherine; Ding, Wuchen; Gaskell, Karen; Jabeen, Naila; Hong, Young Pyo; Shavorskiy, Andrey; Bluhm, Hendrik; Li, Wei-Xue; Jackson, Gregory S; Hussain, Zahid; Liu, Zhi; Eichhorn, Bryan W

2013-08-01

385

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

SciTech Connect

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, 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, Nernst potential, operating potential, activation over-potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Mean per-cell area-specific-resistance (ASR) values decrease with increasing current density. Predicted mean outlet hydrogen and steam concentrations vary linearly with current density, as expected. Effects of variations in operating temperature, gas flow rate, cathode and anode exchange current density, and contact resistance from the base case are presented. Contour plots of local electrolyte temperature, current density, and Nernst potential indicated 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.

Grant Hawkes; James E. O'Brien

2008-10-01

386

The cycle life chemistry of ambient-temperature secondary lithium cells  

NASA Technical Reports Server (NTRS)

The Jet Propulsion Laboratory is involved in a NASA-sponsored research program to demonstrate the feasibility of ambient-temperature secondary lithium batteries for geosynchronous space applications. Encouraging cycle life has been demonstrated in sealed, cathode-limited laboratory cells. However, the cell capacity declines with cycle life. The results of recent studies of the lithium electrode passivation chemistry, and of conductive diluents for TiS2 cathodes and their possible contribution to capacity decline, are here presented. Technical issues associated with the unique operational requirements of a geosynchronous mission are also described.

Somoano, R.; Carter, B. J.; Subba Rao, S.; Shen, D.; Yen, S. P. S.

1985-01-01

387

Paper-based electrochemical cyto-device for sensitive detection of cancer cells and in situ anticancer drug screening.  

PubMed

In this work, using human acute promyelocytic leukemia cells (HL-60) as a model, a novel microfluidic paper-based electrochemical cyto-device (?-PECD) was fabricated to demonstrate a facile, portable, and disposable approach for cancer cell detection and in situ screening of anticancer drugs in a high-throughput manner. In this ?-PECD, aptamers modified three-dimensional macroporous Au-paper electrode (Au-PE) was fabricated and employed as the working electrode for specific and efficient cancer cell capture as well as for sequential in-electrode 3D cell culture. This Au-PE showed enhanced capture capacity for cancer cells and good biocompatibility for preserving the activity of captured living cells. Sensitive cancer cell detection was achieved in this ?-PECD, which could respond down to four HL-60 cells in 10?L volume with a wide linear calibration range from 5.0×10(2) to 7.5×10(7) cellsmL(-1) and exhibited good stability and reproducibility. Then, in situ anticancer drug screening was successfully implemented in this ?-PECD through monitoring of the apoptotic cancer cells after the in-electrode 3D cell culture with drug-containing culture medium, demonstrating its wide range of potential applications to facilitate effective clinical cancer diagnosis and treatment. PMID:25261894

Su, Min; Ge, Lei; Ge, Shenguang; Li, Nianqiang; Yu, Jinghua; Yan, Mei; Huang, Jiadong

2014-10-17

388

An electrochemical treatment to improve corrosion and contact resistance of stainless steel bipolar plates used in polymer electrolyte fuel cells  

NASA Astrophysics Data System (ADS)

An electrochemical surface treatment is presented that improves the properties of stainless steel (316SS) used as bipolar plates for polymer electrolyte fuel cells (PEFCs). The process is an anodic treatment, whereby the material is polarised beyond the transpassive region. Potentiodynamic corrosion testing, chemical and morphological surface characterisation and interfacial contact resistance measurements indicate that the improved properties of 316SS are primarily a consequence of an enrichment of Cr at the near-surface of the material. The surface treatment increases the corrosion resistance and significantly reduces interfacial contact resistance.

Gabreab, Ebrahim M.; Hinds, Gareth; Fearn, Sarah; Hodgson, David; Millichamp, Jason; Shearing, Paul R.; Brett, Daniel J. L.

2014-01-01

389

Electrochemical properties of polyaniline/carboxydextran (PANI/carDEX) composite films for biofuel cells in neutral aqueous solutions.  

PubMed

Electrochemical properties of composite films consisting of polyaniline/carboxydextran (PANI/carDEX) as a biofuel cell electrode platform were investigated. These composite films were formed on a planar gold surface through electropolymerization after a simple chemical modification of dextran with carboxyl groups. Cyclic voltammetry indicated that the composite films retained a redox activity in neutral pH environment. The PANI/carDEX composite films showed an electrocatalytic activity for the oxidation of ascorbic acid. The PANI/carDEX composite films also demonstrated an excellent electron-transfer mediating capability for the bioelectrocatalytic activation of glucose oxidase (GOx) toward the oxidation of glucose. PMID:19205889

Lee, Sunmook; Choi, Bokkyu; Tsutsumi, Atsushi

2009-06-01

390

Fabrication and electrochemical performance of thin-film solid oxide fuel cells with large area nanostructured membranes  

Microsoft Academic Search

Thin-film solid oxide fuel cells (SOFCs) with large (5-mm square) membranes and ultra-thin La0.6Sr0.4Co0.8Fe0.2O3?? (LSCF) cathodes have been fabricated and their electrochemical performance was measured up to 500°C. A grid of plated nickel on the cathode with 5–10?m linewidth and 25–50?m pitch successfully supported a roughly 200-nm-thick LSCF\\/yttria-stabilized zirconia\\/platinum membrane while covering less than 20% of the membrane area. This

Alex C. Johnson; Antonio Baclig; Daniel V. Harburg; Bo-Kuai Lai; Shriram Ramanathan

2010-01-01

391

Abundance of mixed linkage glucan in mature tissues and secondary cell walls of grasses  

PubMed Central

(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

Vega-Sánchez, Miguel E.; Verhertbruggen, Yves; Scheller, Henrik V.; Ronald, Pamela C.

2013-01-01

392

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

PubMed

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 wall was initially secreted as bands composed of discrete masses of stained material, consistent with immobilized sites of cellulose synthesis. The masses coalesced, forming truncated, sinuous or smeared thickenings, as secondary cell wall deposition continued. The absence of ordered cellulose microfibrils was confirmed by polarization microscopy and a lack of fluorescence dichroism as determined by laser scanning microscopy. Indirect immunofluorescence showed that cortical microtubules initially subtended the masses of dye-altered secondary cell wall material but soon became disorganized and disappeared. Although most of the secondary cell wall was deposited in the absence of subtending cortical microtubules in dye-treated cells, secretion remained confined to discrete regions of the plasma membrane. Examination of non-dye-treated cultures following application of microtubule inhibitors during various stages of secondary-cell-wall deposition revealed that the pattern became fixed at an early stage such that deposition remained localized in the absence of cortical microtubules. These observations indicate that cortical microtubules are required to establish, but not to maintain, patterned secondary-cell-wall deposition. Furthermore, cellulose microfibrils play a role in maintaining microtubule arrays and the integrity of the secondary-cell-wall bands during deposition. PMID:15614483

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

2004-12-01

393

Nonlinear coupled equations for electrochemical cells as developed by the general equation for nonequilibrium reversible-irreversible coupling.  

PubMed

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

Bedeaux, Dick; Kjelstrup, Signe; Ottinger, Hans Christian

2014-09-28

394

Nonlinear coupled equations for electrochemical cells as developed by the general equation for nonequilibrium reversible-irreversible coupling  

NASA Astrophysics Data System (ADS)

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.

Bedeaux, Dick; Kjelstrup, Signe; Öttinger, Hans Christian

2014-09-01

395

Graphene-based Electrochemical Energy Conversion and Storage: Fuel cells, Supercapacitors and Lithium Ion Batteries  

Microsoft Academic Search

Graphene has attracted extensive research interest due to its strictly 2-dimensional (2D) structure, which results in its unique electronic, thermal, mechanical, and chemical properties and potential technical applications. These remarkable characteristics of graphene, along with the inherent benefits of a carbon material, make it a promising candidate for application in electrochemical energy devices. This article reviews the methods of graphene

Junbo Hou; Yuyan Shao; Michael A. Ellis; Robert Moore; Baolian Yi

2011-01-01

396

The Kv channel blocker 4-aminopyridine enhances Ag+ uptake: A scanning electrochemical microscopy study of single living cells  

PubMed Central

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

Zhan, Dongping; Fan, Fu-Ren F.; Bard, Allen. J.

2008-01-01

397

Characterization of Damp-Heat Degradation of CuInGaSe2 Solar Cell Components and Devices by (Electrochemical) Impedance Spectroscopy: Preprint  

SciTech Connect

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.

Pern, F. J. J.; Noufi, R.

2011-09-01

398

Laser-adjusted three-dimensional Li-Mn-O cathode architectures for secondary lithium-ion cells  

NASA Astrophysics Data System (ADS)

Three-dimensional cathode architectures for rechargeable lithium-ion cells can provide better Li-ion diffusion due to larger electrochemical active surface area and therefore, may stabilize the cycling behaviour of an electrochemical cell. This features show great importance when aiming for long-life batteries, e.g. in stationary or portable power devices. In this study, lithium manganese oxide thin films were used as cathode material with the goal to stabilize their cycling behavior and to counter degradation effects which come up within the lithium manganese oxide system. Firstly, appropriate laser ablation parameters were selected in order to achieve defined three-dimensional structures with features sizes down to micro- and sub-micrometer scale by using mask imaging technique. Laser annealing was also applied onto the laser structured material in a second step in order to form an electrochemically active phase. Process development led to a laser annealing strategy for a flexible adjustment of crystallinity and grain size. Laser annealing was realized using a high power diode laser system operating at a wavelength of 940 nm. Information on the surface composition, chemistry and topography as well as studies on the crystalline phase of the material were obtained by using Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and X-ray diffraction analysis. The electrochemical activity of the laser modified lithium manganese oxide cathodes was explored by cyclic voltammetry measurements and galvanostatic testing by using a lithium anode and standard liquid electrolyte.

Pröll, J.; Kohler, R.; Torge, M.; Bruns, M.; Przybylski, M.; Ulrich, S.; Seifert, H. J.; Pfleging, W.

2012-03-01

399

Novel Protein Crystal Growth Electrochemical Cell For Applications in X-ray Diffraction and Atomic Force Microscopy  

SciTech Connect

A new crystal growth cell based on transparent indium tin oxide (ITO) glass-electrodes for electrochemically assisted protein crystallization allows for reduced nucleation and crystal quality enhancement. The crystallization behavior of lysozyme and ferritin was monitored as a function of the electric current applied to the growth cell. The X-ray diffraction analysis showed that for specific currents, the crystal quality is substantially improved. No conformational changes were observed in the 3D crystallographic structures determined for crystals grown under different electric current regimes. Finally, the strong crystal adhesion on the surface of ITO electrode because of the electroadhesion allows a sufficiently strong fixing of the protein crystals, to undergo atomic force microscopy investigations in a fluid cell.

G Gil-Alvaradejo; R Ruiz-Arellano; C Owen; A Rodriguez-Romero; E Rudino-Pinera; M Antwi; V Stojanoff; A Moreno

2011-12-31

400

Abstract--Battery packs for most applications are series strings of electrochemical cells. Due to manufacturing variations,  

E-print Network

. For example, a 12 V lead-acid battery is composed of six individual cells in series. Other secondary battery battery users are aware that SOC balance is necessary, particularly for valve-regulated lead-acid (VRLA) and lithium-ion types [1-7]. For flooded lead-acid batteries, at least in low voltage strings, overcharge

Kimball, Jonathan W.

401

Role of secondary lymphoid tissues in primary and memory T-cell responses to a transplanted organ  

PubMed Central

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

Ng, Yue-Harn; Chalasani, Geetha

2009-01-01

402

Toxicological characterization of the landfill leachate prior/after chemical and electrochemical treatment: a study on human and plant cells.  

PubMed

In this research, toxicological safety of two newly developed methods for the treatment of landfill leachate from the Piškornica (Croatia) sanitary landfill was investigated. Chemical treatment procedure combined chemical precipitation with CaO followed by coagulation with ferric chloride and final adsorption by clinoptilolite. Electrochemical treatment approach included pretreatment with ozone followed by electrooxidation/electrocoagulation and final polishing by microwave irradiation. Cell viability of untreated/treated landfill leachate was examined using fluorescence microscopy. Cytotoxic effect of the original leachate was obtained for both exposure periods (4 and 24 h) while treated samples showed no cytotoxic effect even after prolonged exposure time. The potential DNA damage of the untreated/treated landfill leachate was evaluated by the comet assay and cytokinesis-block micronucleus (CBMN) assay using either human or plant cells. The original leachate exhibited significantly higher comet assay parameters compared to negative control after 24 h exposure. On the contrary, there was no significant difference between negative control and chemically/electrochemically treated leachate for any of the parameters tested. There was also no significant increase in either CBMN assay parameter compared to the negative control following the exposure of the lymphocytes to the chemically or electrochemically treated landfill leachate for both exposure periods while the original sample showed significantly higher number of micronuclei, nucleoplasmic bridges and nuclear buds for both exposure times. Results suggest that both methods are suitable for the treatment of such complex waste effluent due to high removal efficiency of all measured parameters and toxicological safety of the treated effluent. PMID:23790829

Garaj-Vrhovac, Vera; Oreš?anin, Višnja; Gajski, Goran; Geri?, Marko; Ruk, Damir; Kollar, Robert; Radi? Brkanac, Sandra; Cvjetko, Petra

2013-10-01

403

The dynamic behavior of thin-film ionic transition metal complex-based light-emitting electrochemical cells  

NASA Astrophysics Data System (ADS)

Light-emitting electrochemical cells (LECs) have received increasing attention during recent years due to their simple architecture, based on solely air-stabile materials, and ease of manufacture in ambient atmosphere, using solution-based technologies. The LEC's active layer offers semiconducting, luminescent as well as ionic functionality resulting in device physical processes fundamentally different as compared with organic light-emitting diodes. During operation, electrical double layers (EDLs) form at the electrode interfaces as a consequence of ion accumulation and electrochemical doping sets in leading to the in situ development of a light-emitting p-i-n junction. In this paper, we comment on the use of impedance spectroscopy in combination with complex nonlinear squares fitting to derive key information about the latter events in thin-film ionic transition metal complex-based light-emitting electrochemical cells based on the model compound bis-2-phenylpyridine 6-phenyl-2,2'-bipyridine iridium(III) hexafluoridophosphate ([Ir(ppy)2(pbpy)][PF6]). At operating voltages below the bandgap potential of the ionic complex used, we obtain the dielectric constant of the active layer, the conductivity of mobile ions, the transference numbers of electrons and ions, and the thickness of the EDLs, whereas the transient thickness of the p-i-n junction is determined at voltages above the bandgap potential. Most importantly, we find that charge transport is dominated by the ions when carrier injection from the electrodes is prohibited, that ion movement is limited by the presence of transverse internal interfaces and that the width of the intrinsic region constitutes almost 60% of the total active layer thickness in steady state at a low operating voltage.

Meier, Sebastian B.; Hartmann, David; Winnacker, Albrecht; Sarfert, Wiebke

2014-09-01

404

The electrochemical generation of useful chemical species from lunar materials  

NASA Astrophysics Data System (ADS)

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.

Tsai, Kan J.; Kuchynka, Daniel J.; Sammells, Anthony F.

405

The electrochemical generation of useful chemical species from lunar materials  

NASA Technical Reports Server (NTRS)

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.

Tsai, Kan J.; Kuchynka, Daniel J.; Sammells, Anthony F.

1990-01-01

406

Bipolar switching polarity reversal by electrolyte layer sequence in electrochemical metallization cells with dual-layer solid electrolytes  

NASA Astrophysics Data System (ADS)

Bipolar switching behaviours of electrochemical metallization (ECM) cells with dual-layer solid electrolytes (SiOx-Ge0.3Se0.7) were analyzed. Type 1 ECM cell, Pt (bottom electrode)/SiOx/Ge0.3Se0.7/Cu (top electrode), exhibited typical eightwise current-voltage (I-V) hysteresis of ECM cells whereas Type 2 ECM cell, Pt (bottom electrode)/Ge0.3Se0.7/SiOx/Cu(top electrode), showed counter-eightwise hysteresis. In addition, absolute off-switching voltage in Type 2 cell is lower than that in Type 1 cell while on-switching voltage in both cells is almost the same. An attempt to understand this electrolyte-stack-sequence-depending switching polarity reversal was made in terms of the ECM cell potential change upon the electrolyte stack sequence and the consequent change in Cu filament growth direction. Relevant experimental evidence for the hypothesis was obtained regarding the switching behaviours. Furthermore, given the switching polarity reversal, feasibility of serial complementary resistive switches was also demonstrated.

Soni, Rohit; Meuffels, Paul; Petraru, Adrian; Hansen, Mirko; Ziegler, Martin; Vavra, Ondrej; Kohlstedt, Hermann; Jeong, Doo Seok

2013-11-01

407

Alternating-polarity operation for complete regeneration of electrochemical deionization system  

DOEpatents

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.

Tran, Tri D. (Livermore, CA); Lenz, David J. (Livermore, CA)

2002-01-01

408

Analysis of cytogenetic effects of the secondary radiation resulting from 70 GeV protons of chinese hamster cells  

NASA Astrophysics Data System (ADS)

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.

Akhmadieva, A. Kh.; Aptikaeva, G. Ph.; Livanova, I. A.; Antipov, A. V.; Akoev, I. G.; Ganassi, E. E.

409

Prevention of secondary stroke and resolution of transfusional iron overload in children with sickle cell anemia using hydroxyurea and phlebotomy  

Microsoft Academic Search

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.

Russell E. Ware; Sherri A. Zimmerman; Pamela B. Sylvestre; Nicole A. Mortier; Jacqueline S. Davis; William R. Treem; William H. Schultz

2004-01-01

410

Electrochemical Detection of the Oligomerization of PB1-F2 Influenza A Virus Protein in Infected Cells.  

PubMed

PB1-F2 is a nonstructural accessory protein of Influenza A virus described to enhance the mortality and the morbidity of the virus in a host-dependent manner. In this work, an electrochemical biosensor based on an immunodetection system was developed to follow the oligomerization of PB1-F2 during the viral cycle. The immunosensor was based on conductive polypyrrole modified with ferrocenyl groups as a redox marker for enhancing signal detection. Antibodies specific for monomeric or oligomeric PB1-F2 forms were immobilized on polypyrrole matrix via biotin/streptavidin layer. We demonstrated that this electrochemical biosensor sensitively detects PB1-F2 in both conformational forms. The linear range extends from 5 nM to 1.5 ?M and from 5 nM to 0.5 ?M for monomeric and oligomeric PB1-F2, respectively. The calculated limit of detection was 0.42 nM for monomeric PB1-F2 and 16 nM for oligomers. The biosensor platform allows the detection and quantification of PB1-F2 in lysates of infected cells during viral cycle. We show that at early stages of viral cycle, PB1-F2 is mainly monomeric but switched to amyloid-like structures at a later stage of infection. The quantification of two protein structural forms points out that PB1-F2 expression profiles and kinetics of oligomerization are cell-type-dependent. PMID:25051456

Miodek, Anna; Vidic, Jasmina; Sauriat-Dorizon, Helene; Richard, Charles-Adrien; Le Goffic, Ronan; Korri-Youssoufi, Hafsa; Chevalier, Christophe

2014-09-16

411

A simple and rapid electrochemical strategy for non-invasive, sensitive and specific detection of cancerous cell.  

PubMed

Developing non-invasive, sensitive and specific sensing strategies for cancerous cell detection with simple and low cost instrumentations provide great advantages in cancer research and early diagnosis of diseases. In the present work, gold nanoparticles (Au NPs) functionalized with recognition components (folic acid) and signal indicator (ferrocene) was designed to fabricate electrochemical cytosensor. The Au NPs can not only accelerate electron transfer between signal indicator and the underlying electrode but also accumulate more ferrocene on the cytosensor surface to magnify signal for improving detection sensitivity. The surface-tethered folic acid plays a key role in specific binding folate receptor-riched HeLa cells on the cytosensor surface, resulting in corresponding current signal change measured by differential pulse voltammetry method. A wide detection range from 10 to 10(6) cells/mL with a detection limit as low as 10 cells/mL for cancerous cells was reached in the presence of a large amount of normal ones with fast differential pulse voltammetry measurement. Detection of the captured cells can be finished within 1 min. The developed strategy provides a new way for operationally simple, rapid, sensitive and specific detection of cancerous cells. PMID:23597898

Xu, Shanling; Liu, Jiyang; Wang, Tianshu; Li, Hailong; Miao, Yuqing; Liu, Yaqing; Wang, Jin; Wang, Erkang

2013-01-30

412

Interactions between MUR10/CesA7-Dependent Secondary Cellulose Biosynthesis and Primary Cell Wall Structure1[OA  

PubMed Central

Primary cell walls are deposited and remodeled during cell division and expansion. Secondary cell walls are deposited in specialized cells after the expansion phase. It is presently unknown whether and how these processes are interrelated. The Arabidopsis (Arabidopsis thaliana) MUR10 gene is required for normal primary cell wall carbohydrate composition in mature leaves as well as for normal plant growth, hypocotyl strength, and fertility. The overall sugar composition of young mur10 seedlings is not significantly altered; however, the relative proportion of pectin side chains is shifted toward an increase in 1 ? 5-?-arabinan relative to 1 ? 4-?-galactan. mur10 seedlings display reduced fucogalactosylation of tightly cell wall-bound xyloglucan. Expression levels of genes encoding either nucleotide sugar interconversion enzymes or glycosyl transferases, known to be involved in primary and secondary cell wall biosynthesis, are generally unaffected; however, the CesA7 transcript is specifically suppressed in the mur10-1 allele. The MUR10 locus is identical with the CesA7 gene, which encodes a cellulose catalytic subunit previously thought to be specifically involved in secondary cell wall formation. The xylem vessels in young mur10 hypocotyls are collapsed and their birefringence is lost. Moreover, a fucogalactosylated xyloglucan epitope is reduced and a 1 ? 5-?-arabinan epitope increased in every cell type in mur10 hypocotyls, including cells that do not deposit secondary walls. mur10 also displays altered distribution of an arabinogalactan-protein epitope previously associated with xylem differentiation and secondary wall thickening. This work indicates the existence of a mechanism that senses secondary cell wall integrity and controls biosynthesis or structural remodeling of primary cell walls and cellular differentiation. PMID:17041031

Bosca, Sonia; Barton, Christopher J.; Taylor, Neil G.; Ryden, Peter; Neumetzler, Lutz; Pauly, Markus; Roberts, Keith; Seifert, Georg J.

2006-01-01

413

Electrochemical properties of sulfur electrode containing nano Al2O3 for lithium\\/sulfur cell  

Microsoft Academic Search

To prevent the dissolution of lithium polysulfides into liquid electrolyte and to promote the lithium\\/sulfur redox reaction, nano-sized Al2O3 particles having large specific surface area were added into sulfur electrode. The effects of nano-sized Al2O3 particles on the electrochemical properties of sulfur electrode for lithium\\/sulfur battery were investigated using CV measurements, charge\\/discharge tests and ionic conductivity measurements of liquid electrolyte.

Y. J. Choi; B. S. Jung; D. J. Lee; J. H. Jeong; K. W. Kim; H. J. Ahn; K. K. Cho; H. B. Gu

2007-01-01

414

Catalysis-electrochemical determination of zeptomole enzyme and its application for single-cell analysis.  

PubMed

A novel electrochemical method for determination of zeptomole amounts of enzyme was developed by a combination of on-capillary enzyme-catalyzed reaction and electrochemical detection. A limit of detection (LOD) of zeptomole (zmol, 10(-)(21) mol) was achieved by monitoring the product of the enzyme-catalyzed reaction. In this method, after enzyme molecules were electrokinetically injected into the capillary, they were electromigrated to the section of the capillary immersed in a warm water bath, where the enzyme molecules reacted with the enzyme substrates in the running buffer in the presence of the activator of the enzyme-catalyzed reaction. Then the electroactive product zone of the enzyme-catalyzed reaction was electromigrated to the horn-shaped outlet of the capillary and electrochemically detected by a carbon fiber disk bundle electrode at a constant potential. Glucose-6-phosphate dehydrogenase (G6PDH) was chosen as the model enzyme. A LOD of 1.3 zmol was achieved. This method was applied to determine zeptomoles of G6PDH in individual human erythrocytes. PMID:14615980

Sun, Xuemei; Jin, Wenrui

2003-11-15

415

In?situ X-ray spectromicroscopy investigation of the material stability of SOFC metal interconnects in operating electrochemical cells.  

PubMed

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

Bozzini, Benedetto; Tondo, Elisabetta; Prasciolu, Mauro; Amati, Matteo; Abyaneh, Majid Kazemian; Gregoratti, Luca; Kiskinova, Maya

2011-08-22

416

[Mechanism exploration on synthesis of secondary metabolites in Sorbus aucuparia cell cultures treated with yeast extract].  

PubMed

Suspension cultures cell of Sorbus aucuparia (SASC) was used as materials, the changes of physiological and biochemical indexes of SASC after treatment with yeast extract (YE) were detected, and the synthetic mechanism of secondary metabolites in SASC treated with YE was preliminarily explored. The results were as follows: under the assay conditions, SASC was induced to synthesize five biphenyl compounds, and these compounds content changed differently with induction time prolonging; YE treatment inhibited cell growth, the culture medium pH was gradually reduced after treatment; water-soluble protein content showed a trend of slow decline, which was significantly increased in YE treatment group (YE group) compared with the control group (CK group), the maximum relative content was 147.76% in contrast with CK group; both YE group and CK group were extracellular Ca2+ flow influx, but the YE group flow was significantly slow than CK group. The results indicate that YE induced the cells in a stress state, which was not conducive to the growth of cells and forced the cells to synthesize biphenyl compounds against external stress; water-soluble protein may serve as intracellular enzymes involved in the synthesis of compounds regulation; Ca2+ may as signal molecule mediate cell signal transduction respond to YE stress. PMID:25272834

Huang, Lei; Xiao, Wen-Juan; Yang, Guang; Mo, Ge; Lin, Shu-Fang; Wu, Zhi-Gang; Guo, Lan-Ping

2014-06-01

417

Cutting edge: resident memory CD8 T cells occupy frontline niches in secondary lymphoid organs.  

PubMed

Resident memory CD8 T cells (TRM) are a nonrecirculating subset positioned in nonlymphoid tissues to provide early responses to reinfection. Although TRM are associated with nonlymphoid tissues, we asked whether they populated secondary lymphoid organs (SLO). We show that a subset of virus-specific memory CD8 T cells in SLO exhibit phenotypic signatures associated with TRM, including CD69 expression. Parabiosis revealed that SLO CD69(+) memory CD8 T cells do not circulate, defining them as TRM. SLO TRM were overrepresented in IL-15-deficient mice, suggesting independent regulation compared with central memory CD8 T cells and effector memory CD8 T cells. These cells were positioned at SLO entry points for peripheral Ags: the splenic marginal zone, red pulp, and lymph node sinuses. Consistent with a potential role in guarding SLO pathogen entry points, SLO TRM did not vacate their position in response to peripheral alarm signals. These data extend the range of tissue resident memory to SLO. PMID:24600038

Schenkel, Jason M; Fraser, Kathryn A; Masopust, David

2014-04-01

418

In-Cell NMR Characterization of the Secondary Structure Populations of a Disordered Conformation of ?-Synuclein within E. coli Cells  

PubMed Central

?-Synuclein is a small protein strongly implicated in the pathogenesis of Parkinson’s disease and related neurodegenerative disorders. We report here the use of in-cell NMR spectroscopy to observe directly the structure and dynamics of this protein within E. coli cells. To improve the accuracy in the measurement of backbone chemical shifts within crowded in-cell NMR spectra, we have developed a deconvolution method to reduce inhomogeneous line broadening within cellular samples. The resulting chemical shift values were then used to evaluate the distribution of secondary structure populations which, in the absence of stable tertiary contacts, are a most effective way to describe the conformational fluctuations of disordered proteins. The results indicate that, at least within the bacterial cytosol, ?-synuclein populates a highly dynamic state that, despite the highly crowded environment, has the same characteristics as the disordered monomeric form observed in aqueous solution. PMID:23991082

Waudby, Christopher A.; Camilloni, Carlo; Fitzpatrick, Anthony W. P.; Cabrita, Lisa D.; Dobson, Christopher M.; Vendruscolo, Michele; Christodoulou, John

2013-01-01

419

Half-Cell Potential Analysis of an Ammonia Sensor with the Electrochemical Cell Au | YSZ | Au, V2O5-WO3-TiO2  

PubMed Central

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

Schonauer-Kamin, Daniela; Fleischer, Maximilian; Moos, Ralf

2013-01-01

420

Bio-mimetically synthesized Ag@BSA microspheres as a novel electrochemical biosensing interface for sensitive detection of tumor cells.  

PubMed

The use of a novel cytosensor, comprised of bio-mimetically synthesized Ag@BSA composite microspheres, for the detection of KB cells (a model system) is described. The Ag@BSA composite microspheres were immobilized on Au electrodes via Au-thiol bonds. Scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM) images revealed that the Ag@BSA were well-dispersed microspheres with an average diameter of 500 nm, including the monolayer of BSA. The immobilization of Ag@BSA composite microspheres onto Au electrodes is thought to increase the electrode surface area and accelerate the electron transfer rate while providing a highly stable matrix for the convenient conjugation of target molecules (such as folic acid) and the prolonged incubation of cells. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies showed that the fabricated cytosensor was able to detect KB cells ranging from 6.0×10(1) to 1.2×10(8) cells mL(-1) with a lower detection limit of 20 cells mL(-1). Due to its facile synthesis, high stability and reproducibility and cytocompatibility, the novel cytosensor described here could find multifarious uses in applications, such as cancer diagnosis, drug screening and cell adhesion studies. PMID:23069357

Hu, Chenyi; Yang, Da-Peng; Wang, Zhihua; Huang, Peng; Wang, Xiansong; Chen, Di; Cui, Daxiang; Yang, Mo; Jia, Nengqin

2013-03-15

421

Computer-Based Study of Secondary Emission Cell (SEC) Efficiency Compared to That of a Vacuum-Type Direct Collection Cell  

Microsoft Academic Search

The concept of directly collecting secondary electrons created by beta emission through an electrical insulator has been proposed as an attractive low-voltage nuclear battery termed a secondary emission cell (SEC). In this paper, a MATLAB computer simulation of an SEC is conducted using Mott scattering, the Penfold-Katz slowing approximation, Bethe's ionization loss expression, and energy and momentum conservation. The goal

Michael Romer; George H. Miley; Nie Luo

2008-01-01

422

Cell cytotoxicity and mycotoxin and secondary metabolite production by common penicillia on cheese agar.  

PubMed

Known or potential new fungal starter culture species such as Penicillium camemberti, P. roqueforti, P. nalgiovense, P. caseifulvum, and P. solitum have been cultivated on a cheese agar medium together with the common cheese contaminants P. commune, P. crustosum, P. discolor, P. atramentosum, and P. nordicum. Secondary metabolites were extracted and analyzed by HPLC-DAD and tested for cytotoxicity by using the MTT-cell culture assay. Metabolites such as cyclopiazonic acid, roquefortine C, and penitrem A, previously reported from cheese, were detected together with sclerotigenin, solistatin, meleagrin, oxaline, compactins, diaportins, chaetoglobosins, rugulovasines, verrucolones, anacines, verrucines, cyclopeptines, viridicatins, and viridic acid, all metabolites not previously reported from cheese. The two P. nalgiovense extracts were the most toxic in the MTT-cell culture test. These extracts contained diaportines together with a number of unknown compounds. P. roqueforti extracts were not toxic at all. Fungal extracts from the rest of the studied penicillia were toxic at levels between these two extremes. PMID:12358494

Larsen, Thomas Ostenfeld; Gareis, Manfred; Frisvad, Jens Christian

2002-10-01

423

Fabrication of silicon nanopillar arrays by cesium chloride self-assembly and wet electrochemical etching for solar cell  

NASA Astrophysics Data System (ADS)

A simple technology with cesium chloride (CsCl) self-assembly lithography and wet electrochemical etching is introduced to fabricate the wafer scale, disordered, well-aligned, and high aspect ratio silicon nanopillars. The original nano structures of CsCl islands with diameters of 500-2000 nm are formed by self-assembly and used as template of lift-off for the nanoporous gold film for wet electrochemical etching as the catalyst in etching solution of HF and H2O2. The average diameter of silicon nanopillars is determined by the CsCl nanoislands with 500-2000 nm, and the height of silicon nanopillars is mainly determined by the etching time in etching solution with 3-12 ?m. The aspect ratio can achieve to 60. The solar cells with different height nanopillars are made for the research of photovoltaic conversion efficiency (PCE). The reflectance of the nanopillars with different height is measured from the wavelength of 400 to 1000 nm and the 9 ?m height silicon nanopillars has the lowest one which is below 3%. The PCE shows the highest value of 14.19% at the condition of 3 ?m height nanopillars and 12.18% of planar one with the same fabrication process.

Liu, Jing; Zhang, Xinshuai; Dong, Gangqiang; Liao, Yuanxun; Wang, Bo; Zhang, Tianchong; Yi, Futing

2014-01-01

424

Electrochemical behavior and biological response of Mesenchymal Stem Cells on cp-Ti after N-ions implantation  

NASA Astrophysics Data System (ADS)

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.

Rizwan, M.; Ahmad, A.; Deen, K. M.; Haider, W.

2014-11-01

425

Cyto-sensing in electrochemical lab-on-paper cyto-device for in-situ evaluation of multi-glycan expressions on cancer cells.  

PubMed

A novel electrochemical lab-on-paper cyto-device (ELPCD) was fabricated to demonstrate sensitive and specific cancer cell detection as well as in-situ monitoring of multi-glycans on living cancer cells. In this ELPCD, aptamers modified three-dimensional macroporous Au-paper electrode (Au-PE) was employed as the working electrode for specific and efficient cancer cell capture. Using a sandwich format, sensitive and reproducible cell detection was achieved in this ELPCD on the basis of the electrochemical signal amplification of the Au-PE and the horseradish peroxidase-lectin electrochemical probe. The ELPCD displayed excellent analytical performance for the detection of four K562 cells with a wide linear calibration range from 550 to 2.0×10(7) cells mL(-1). Then, this ELPCD was successfully applied to determine cell-surface multi-glycans in parallel and in-situ monitor multi-glycans expression on living cells in response to drug treatment through in-electrode 3D cell culture. The proposed method provides promising application in decipherment of the glycomic codes as well as clinical diagnosis and treatment in early process of cancer. PMID:25104432

Su, Min; Ge, Lei; Kong, Qingkun; Zheng, Xiaoxiao; Ge, Shenguang; Li, Nianqiang; Yu, Jinghua; Yan, Mei

2015-01-15

426

Method of making sulfur tolerant composite cermet electrodes for solid oxide electrochemical cells  

SciTech Connect

An electrochemical apparatus is made containing an exterior electorde bonded to the exterior of a tubular, solid, oxygen ion conducting electrolyte where the electrolyte is also in contact with an interior electrode, said exterior electrode comprising particles of an electronic conductor contacting the electrolyte, where a ceramic metal oxide coating partially surrounds the particles and is bonded to the electrolyte, and where a coating of an ionic-electronic conductive material is attached to the ceramic metal oxide coating and to the exposed portions of the particles.

Isenberg, Arnold O. (Pittsburgh, PA)

1989-01-01

427

Porous silicon layers prepared by electrochemical etching for application in silicon thin film solar cells  

NASA Astrophysics Data System (ADS)

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.

Dubey, R. S.; Gautam, D. K.

2011-09-01

428

Electrochemical fabrication of capacitors  

DOEpatents

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.

Mansour, Azzam N. (Fairfax Sta., VA); Melendres, Carlos A. (Lemont, IL)

1999-01-01

429

Niemann-Pick disease, type B with TRAP-positive storage cells and secondary sea blue histiocytosis.  

PubMed

We present 2 cases of Niemann Pick disease, type B with secondary sea-blue histiocytosis. Strikingly, in both cases the Pick cells were positive for tartrate resistant acid phosphatase, a finding hitherto described only in Gaucher cells. This report highlights the importance of this finding as a potential cytochemical diagnostic pitfall in the diagnosis of Niemann Pick disease. PMID:19864213

Sharma, P; Kar, R; Dutta, S; Pati, H P; Saxena, R

2009-01-01