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1

Primary and Secondary Room Temperature Molten Salt Electrochemical Cells.  

National Technical Information Service (NTIS)

Three primary cells (a, b, and c) and two secondary cell candidates (d and e) were examined using room temperature molten salts as electrolytes in each case: (a) A1 anode / A1C13-MEIC1 (N=0.37) // FeC13-MEIC1 (N=0.33) / W cathode (b) A1 anode / A1C13-MEIC...

G. F. Reynolds C. J. Dymek

1985-01-01

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, Neil C. (Chicago, IL) [Chicago, IL; Warner, Barry T. (South Holland, IL) [South Holland, IL; Smaga, John A. (Lemont, IL) [Lemont, IL; Battles, James E. (Oak Forest, IL) [Oak Forest, IL

1983-01-01

3

Electrochemical cell  

DOEpatents

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

Kaun, Thomas D. (New Lenox, IL)

1984-01-01

4

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. The improvement comprises forming a slurry of solid particles dispersed in a liquid electrolyte such as the lithium chloride-potassium chloride eutetic, 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, Franklin C. (Hickory Hills, IL); Battles, James E. (Oak Forest, IL)

1983-01-01

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 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

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 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) [Downers Grove, IL; Vissers, Donald R. (Naperville, IL) [Naperville, IL; Prakash, Jai (Downers Grove, IL) [Downers Grove, IL

1994-01-01

9

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

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

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

1996-07-02

12

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

13

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

14

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

15

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

16

Portable electrochemical cell interrogator  

SciTech Connect

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

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

1984-11-01

17

Nanocrystalline electrochemical solar cells  

Microsoft Academic Search

Standard solar cells exploit the physics of semiconductors in which the energy of absorbed photons excites charge-carrier pairs which are subsequently separated by the influence of a solid state junction to provide a photovoltage. In the nanocrystalline electrochemical cell, the optical absorber is a dye monolayer which after photo-excitation injects electrons into a semiconductor substrate, with charge neutrality being restored

A. J. McEvoy; M. Gratzel; H. Wittkopf; D. Jestell; J. Benemann

1994-01-01

18

Calculating Pressures In Electrochemical Cells  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

19

Miniaturized Electrochemical Flow Cells  

PubMed Central

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

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

2006-01-01

20

Electrochemical Noise in Lithium Primary Cells.  

National Technical Information Service (NTIS)

Electrochemical noise is interpreted as the occurrence of microscopic fluctuations of the potential of an electrochemical cell. A study was conducted on a number of commercial lithium cells to evaluate the practicality of electrochemical noise measurement...

G. J. Donaldson W. S. Nip T. J. Patraboy J. S. Anderson M. D. Farrington

1991-01-01

21

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

22

Method for manufacturing an electrochemical cell  

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

1982-01-01

23

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

24

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

25

Method of Monitoring Electrochemical Cells.  

National Technical Information Service (NTIS)

The physical and electrical condition of electrochemical cells of a battery is monitored on a continuous basis so that corrective action can be taken before explosion and/or venting occurs by a method including the steps of: A) coating the electrically co...

G. J. Malinowski D. M. Chaskin

1986-01-01

26

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

27

Electrochemical sensor for monitoring electrochemical potentials of fuel cell components  

DOEpatents

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

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

1993-01-01

28

Metal halogen electrochemical cell  

DOEpatents

It has now been discovered that reduction in the coulombic efficiency of metal halogen cells can be minimized if the microporous separator employed in such cells is selected from one which is preferably wet by the aqueous electrolyte and is not wet substantially by the cathodic halogen.

Bellows, Richard J. (Hampton, NJ); Kantner, Edward (E. Brunswick, NJ)

1988-08-23

29

Compacted carbon for electrochemical cells  

SciTech Connect

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

30

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: (1) an x-ray density of at least 2.00 grams per cubic centimeters, (2) a closed porosity of no greater than 5%, and (3) an open porosity of no greater than 47%; and (b) graphite having the following properties: (1) an x-ray density of at least 2.20 grams per cubic centimeters, (2) a closed porosity of no greater than 5%, and (3) 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 counter electrode. 10 figs.

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

1997-10-14

31

Method of monitoring electrochemical cells  

SciTech Connect

This patent describes the method of monitoring on a continuous basis the physical and electrical condition of electrochemical cells of a battery so that corrective action can be taken before explosion and/or venting occurs, and wherein each of the electrochemical cells has an electrically conductive shell. The method includes the steps of: (A) coating the electrically conductive shell of each cell of the battery with a thin non electrically conductive layer, (B) applying a sensor stripe over the non electrically conductive layer so that the sensor does not make electrical contact to the shell of the cell, wherein the sensor stripe is comprised of multiple sensor elements including a conductive thermally sensitive material and a conductive stress/strain material, and wherein the materials are connected together to form a continuous series electrical path using bonding pads of a metallic material to interface the junctions of the conductive thermally sensitive material and the sensor leads. (C) connecting leads to the sensor and then coating the sensor with a protective layer, and (D) connecting the sensor leads of individual cells of the battery into an electrical series circuit, the remaining leads of the series sensor circuit being connected to an alarm/control network that monitors the conductivity of the series electrical path.

Malinowski, G.J.; Chaskin, D.M.

1988-02-23

32

Electrochemical cell having cyclindircal electrode elements  

SciTech Connect

A secondary, high temperature electrochemical cell especially adapted for lithium alloy negative electrodes, transition metal chalcogenide positive electrodes and alkali metal halide or alkaline earth metal halide electrolyte is disclosed. The cell is held within an elongated cylindrical container in which one of the active materials is filled around the outside surfaces of a pluraity of perforate tubular current collectors along the length of the container. Each of the current collector tubes contain a concentric atubular layer of electrically insulative ceramic as an interelectrode separator. The active material of opposite polarity in elongated pin shape is positioned longitudinally within the separator layer. A second electrically conductive tube with perforate walls can be swagged or otherwise bonded to the outer surface of the pin as a current cllector and the electrically insulative ceramic layer can be coated or otherwise layered onto the outer surface of this second current collector. Alternatively, the central pin electrode can include an axial core as a current collector.

Nelson, P.A.; Shimotake, H.

1981-03-05

33

Method of monitoring electrochemical cells  

SciTech Connect

The physical and electrical condition of electrochemical cells of a battery is monitored on a continuous basis so that corrective action can be taken before explosion and/or venting occurs by a method including the steps of: A) coating the electrically conductive shell of each cell of the battery with a thin nonelectrically conductive layer, B) applying a sensor stripe over the non electrically conductive layer so that the sensor stripe does not make electrical contact to the shell of the cell, C) connecting leads to the sensor and then coating the sensor with a protective layer, and D) connecting the sensor leads of individual cells of the battery into an electrical series circuit, the remaining leads of the series sensor circuit being connected to an alarm/control network that monitors the conductivity of the series electrical path.

Malinowski, G.J.; Chaskin, D.M.

1986-02-12

34

Trends in Cell-Based Electrochemical Biosensors  

Microsoft Academic Search

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

Lin Ding; Dan Du; Xueji Zhang; Huangxian Ju

2008-01-01

35

Electrochemical cell and negative electrode therefor  

DOEpatents

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

Kaun, Thomas D. (New Lenox, IL)

1982-01-01

36

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

37

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: (1) the electrode, (2) 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 (3) a counter electrode; 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. 3 figs.

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

1998-05-26

38

Electrochemical characteristics of lithium-ion cells.  

National Technical Information Service (NTIS)

The authors describe below the electrochemical performance characteristics, including charge-discharge characteristics at different rates, of cylindrical 18650 (18 mm diameter, 65 mm high) and prismatic lithium ion cells at ambient and sub-ambient tempera...

C. Nagasubramanian P. Roth R. G. Jungst N. Clark

1998-01-01

39

New Materials for Electrochemical Cells.  

National Technical Information Service (NTIS)

The research had two main aims: (i) determination of the thermochemical, structural and electrochemical properties of insertion compounds and materials showing mixed electronic/ionic conduction, and (ii) the design, preparation and characterization of new...

J. B. Goodenough P. G. Dickens

1987-01-01

40

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

41

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

42

Improved magnesium/manganese dioxide electrochemical cell  

SciTech Connect

The demand for improved energy-storage systems has increased greatly with the evolution of new equipment requiring new and improved battery systems as a power source. Critical characteristics that power sources must accommodate are low cost, high energy density, light weight, and good storability. The present magnesium/manganese dioxide electrochemical system provides high energy density at low cost. A magnesium/manganese dioxide electrochemical cell that has been stored following partial usage is improved by increasing the cathode moisture content at the time of making the cell to reduce the self discharge and increase the operating capacity after the cell has been stored following partial usage.

Jarvis, L.P.; Brundage, M.T.; Atwater, T.

1988-04-14

43

New Materials for Electrochemical Cells.  

National Technical Information Service (NTIS)

Determination of the thermochemical, structural and basic electrochemical properties of mixed electronic/ionic conductors was successfully carried out on the following systems: H(x)MoO3, Li(x)V2O5, H(x)WO3, and Li(x)MoO3. Attempts to design new protonic a...

J. B. Goodenough P. G. Dickens

1981-01-01

44

Gas recombination assembly for electrochemical cells  

DOEpatents

An assembly for recombining gases generated in electrochemical cells wherein a catalyst strip is enveloped within a hydrophobic, gas-porous film which, in turn, is encased between gas-porous, metallic layers. The sandwich construction of metallic layers and film is formed into a spiral with a tab for connection to the cell.

Levy, Isaac (New Fairfield, CT); Charkey, Allen (Brookfield, CT)

1989-01-01

45

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

46

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

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

1997-06-17

47

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

48

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

49

Reversible photovoltaic-electrochemical solar cell  

Microsoft Academic Search

The development of a novel solar electrochemical rechargeable battery is reported. The device uses n-BaTiO3 as photo-anode for charging by sunlight, and Pt electrodes for the dark, reverse reaction. The electrolyte is Ce(3+)\\/Ce(4+) solution, which behaves like a cathode during charging. The cell has a potential of 0.62 V and a current on the order of 0.20 mA\\/sq cm. The

M. Sharon; A. Sinha

1981-01-01

50

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

Microsoft Academic Search

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

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

2002-01-01

51

Porous electronic current collector bodies for electrochemical cell configurations  

DOEpatents

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

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

1989-01-01

52

Thin film electrochemical power cells  

NASA Astrophysics Data System (ADS)

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

Owens, Boone B.; Smyrl, William H.

1991-08-01

53

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

54

High energy density electrochemical cell  

NASA Technical Reports Server (NTRS)

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

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

1970-01-01

55

Electrochemical and quartz microbalance technique studies of anode material for secondary lithium batteries  

Microsoft Academic Search

The lithium metal anode for secondary lithium batteries was studied using the electrochemical and the quartz crystal microbalance (QCM) techniques. The solutions studied were: (i) propylene carbonate (PC) containing LiClO4, and (ii) ?-butyrolactone (?-BL) containing LiPF6. Surface film formation on the electrodes in these solutions was investigated during galvanostatic electrodeposition of lithium. Moreover, the influence of the surface films upon

Shinji Koike; Takuya Fujieda; Noboru Wakabayashi; Shunichi Higuchi

1997-01-01

56

Solid oxide electrochemical cell fabrication process  

DOEpatents

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

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

1992-01-01

57

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

58

Organic electrolyte for use in a lithium rechargeable electrochemical cell and lithium rechargeable electrochemical cell including said organic electrolyte  

SciTech Connect

This invention relates in general to use of an organic electrolyte in a lithium rechargeable electrochemical cell and to a lithium rechargeable electrochemical cell including said electrolyte; and, in particular, to the use of 1 to 2 mol/dm/sup 3/ LiAsF/sub 6/ in dimethylcarbonate (DMC) or 1 to 2 mol/dm/sup 3/ LiAsF/sub 6/ in (DMC) mixtures with methyl formate (MF) in which the mass percent of the (DMC) can vary from 25 to 100 mass percent as the electrolyte in a lithium rechargeable electrochemical cell, and to a lithium rechargeable electrochemical cell including said electrolyte.

Plichta, E.J.; Slane, S.M.; Salomon, M.

1987-07-06

59

Sensor apparatus using an electrochemical cell  

DOEpatents

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

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

2002-01-01

60

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

61

Characterization of Ion Movement in Light-Emitting Electrochemical Cells via ToF-SIMS  

NASA Astrophysics Data System (ADS)

An emerging advantage of organic semiconductors is their ability to conduct ions in applications such as light-emitting electrochemical cells (LECs), photovoltaic devices, and electrochromic devices. This ability of organic materials to conduct both ionic and electronic currents in the solid state sets these materials apart from their inorganic counterparts. However the fundamental electrochemical processes are not well characterized. 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. Here, we present our findings from direct profiling 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 correlation between ion profiles and device performance and potential approaches to tuning electrochemical doping processes in LECs.

Shoji, Tyko; Zhu, Zihua; Ilkevich, Anton; Leger, Janelle

2013-03-01

62

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

SciTech Connect

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

Kaun, T.D.

1981-07-29

63

Thermal regeneration of an electrochemical concentration cell  

DOEpatents

A system and method for thermally regenerating an electrochemical concentration cell having first and second aluminum electrodes respectively positioned in contact with first and second electrolytes separated by an ion exchange member, the first and second electrolytes being composed of different concentrations of an ionic solvent and a salt, preferably an aluminum halide. The ionic solvent may be either organic or inorganic with a relatively low melting point, the ionic solvent and the salt form a complex wherein the free energy of formation of said complex is less than about -5 Kcal/mole. A distillation column using solar heat or low grade industrial waste heat receives the first and second electrolytes and thermally decomposes the salt-solvent complex to provide feed material for the two half cells.

Krumpelt, Michael (Naperville, IL); Bates, John K. (Plainfield, IL)

1981-01-01

64

Thermal regeneration of an electrochemical concentration cell  

DOEpatents

A system and method are described for thermally regenerating an electrochemical concentration cell having first and second aluminum electrodes respectively positioned in contact with first and second electrolytes separated by an ion exchange member, the first and second electrolytes being composed of different concentrations of an ionic solvent and a salt, preferably an aluminum halide. The ionic solvent may be either organic or inorganic with a relatively low melting point, the ionic solvent and the salt form a complex wherein the free energy of formation of said complex is less than about -5 kcal/mole. A distillation column using solar heat or low grade industrial waste heat receives the first and second electrolytes and thermally decomposes the salt-solvent complex to provide feed material for the two half cells.

Krumpelt, M.; Bates, J.K.

1980-05-09

65

New materials for electrochemical cells. Final report  

SciTech Connect

Determination of the thermochemical, structural and basic electrochemical properties of mixed electronic/ionic conductors was successfully carried out on the following systems: H(x)MoO3, Li(x)V2O5, H(x)WO3, and Li(x)MoO3. Attempts to design new protonic and Li(+)ion conductors have opened up two fields: One is the recognition of particle hydrates as protonic electrolytes capable of fabrication into dense ceramics by cold pressing; we have obtained room-temperature H(+)ion conductivity approaching .01/ohm/cm in cold-pressing Sb(.2)O(5.5).4H2O. The other is the use of low-temperature chemical and electrochemical techniques to prepare new materials not attainable with high-temperature techniques. With this method we have prepared Li/Li (1-x) Cobalt dioxide cells having open-circuit voltages in excess of 4 V. We have also initiated studies into composite electrolyte/electrode materials using room-temperature molten salts immobilized by insertion-compound electrode materials.

Goodenough, J.B.; Dickens, P.G.

1981-12-31

66

Composite electrode for use in electrochemical cells  

DOEpatents

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

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

1987-10-16

67

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

68

Chemically imaging living cells by scanning electrochemical microscopy  

Microsoft Academic Search

Scanning electrochemical microscopy (SECM) is useful in probing and characterizing interfaces at high resolution. In this paper, the general principles of this technique are described and several applications of SECM to biological systems, particularly to living cells, is discussed, along with several example systems. Thiodione was detected and monitored electrochemically during the treatment of hepatocytes with cytotoxic menadione. The antimicrobial

Allen J. Bard; Xiao Li; Wei Zhan

2006-01-01

69

Hazards of Secondary Bromadiolone Intoxications Evaluated using High-performance Liquid Chromatography with Electrochemical Detection  

PubMed Central

This study reported on the possibility of intoxications of non-target wild animals associated with use of bromadiolone as the active component of rodenticides with anticoagulation effects. A laboratory test was done with earthworms were exposed to bromadiolone-containing granules under the conditions specified in the modified OECD 207 guideline. No mortality of earthworms was observed during the fourteen days long exposure. When the earthworms from the above test became a part of the diet of common voles in the following experiment, no mortality of consumers was observed too. However, electrochemical analysis revealed higher levels of bromadiolone in tissues from earthworms as well as common voles compared to control animals. There were determined comparable levels of bromadiolone in the liver tissue of common voles after primary (2.34±0.10 ?g/g) and secondary (2.20±0.53 ?g/g) intoxication. Therefore, the risk of secondary intoxication of small mammalian species feeding on bromadiolone-containing earthworms is the same as of primary intoxication through baited granules. Bromadiolone bio-accumulation in the food chain was monitored using the newly developed analytical procedure based on the use of a liquid chromatography coupled with electrochemical detector (HPLC-ED). The HPLC-ED method allowed to determine the levels of bromadiolone in biological samples and is therefore suitable for examining the environmental hazards of this substance.

Krizkova, Sona; Beklova, Miroslava; Pikula, Jiri; Adam, Vojtech; Horna, Ales; Kizek, Rene

2007-01-01

70

Scanning droplet cell for high throughput electrochemical and photoelectrochemical measurements.  

PubMed

High throughput electrochemical techniques are widely applied in material discovery and optimization. For many applications, the most desirable electrochemical characterization requires a three-electrode cell under potentiostat control. In high throughput screening, a material library is explored by either employing an array of such cells, or rastering a single cell over the library. To attain this latter capability with unprecedented throughput, we have developed a highly integrated, compact scanning droplet cell that is optimized for rapid electrochemical and photoeletrochemical measurements. Using this cell, we screened a quaternary oxide library as (photo)electrocatalysts for the oxygen evolution (water splitting) reaction. High quality electrochemical measurements were carried out and key electrocatalytic properties were identified for each of 5456 samples with a throughput of 4 s per sample. PMID:23464227

Gregoire, John M; Xiang, Chengxiang; Liu, Xiaonao; Marcin, Martin; Jin, Jian

2013-02-01

71

Scanning droplet cell for high throughput electrochemical and photoelectrochemical measurements  

NASA Astrophysics Data System (ADS)

High throughput electrochemical techniques are widely applied in material discovery and optimization. For many applications, the most desirable electrochemical characterization requires a three-electrode cell under potentiostat control. In high throughput screening, a material library is explored by either employing an array of such cells, or rastering a single cell over the library. To attain this latter capability with unprecedented throughput, we have developed a highly integrated, compact scanning droplet cell that is optimized for rapid electrochemical and photoeletrochemical measurements. Using this cell, we screened a quaternary oxide library as (photo)electrocatalysts for the oxygen evolution (water splitting) reaction. High quality electrochemical measurements were carried out and key electrocatalytic properties were identified for each of 5456 samples with a throughput of 4 s per sample.

Gregoire, John M.; Xiang, Chengxiang; Liu, Xiaonao; Marcin, Martin; Jin, Jian

2013-02-01

72

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

73

Thermal conductor for high-energy electrochemical cells  

DOEpatents

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

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

2000-01-01

74

Steel refining with an electrochemical cell  

DOEpatents

Apparatus for processing a metallic fluid containing iron oxide, container for a molten metal including an electrically conductive refractory disposed for contact with the molten metal which contains iron oxide, an electrolyte in the form of a basic slag on top of the molten metal, an electrode in the container in contact with the slag electrically separated from the refractory, and means for establishing a voltage across the refractory and the electrode to reduce iron oxide to iron at the surface of the refractory in contact with the iron oxide containing fluid. A process is disclosed for refining an iron product containing not more than about 10% by weight 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.

Blander, Milton (Palos Park, IL); Cook, Glenn M. (Naperville, IL)

1988-01-01

75

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

76

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

77

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

78

Electrochemical characterization of transition metal oxide aerogels for secondary lithium batteries  

NASA Astrophysics Data System (ADS)

The ability of transition metals to exist in multiple valence states, along with the fact that many transition metal oxides have a layered structure, has made transition metal oxides prime candidates as electrodes for the emerging technology of secondary lithium batteries. Traditionally, the electrochemical behavior of these materials is considered to be intrinsic to the material. In order to obtain different electrochemical performance needs, different materials need to be selected. The principal objective of this dissertation is to correlate electrochemical behavior with the microstructure of a material, allowing a material to meet different application requirements through the control of its microstructure. In this research, three different studies are used to explore the interrelationship between microstructure and electrochemical behavior. Sol-gel chemistry is used exclusively to prepare the electrochemically active materials as this process enables one to control the resulting microstructure and morphology. The first study looks at the influence of the degree of crystallinity in MoO3 aerogels on lithium capacity. The degree of crystallinity is controlled through heat treatment and observed to affect the lithium capacity. The nanocrystalline MoO3 aerogel exhibited higher lithium capacity (1.5 Li/Mo) compared to both the amorphous (1.1 Li/Mo) and crystalline (1.1 Li/Mo) samples. The second study involves the synthesis of organic/inorganic hybrids, achieved by simultaneously polymerizing the polypyrrole network within the Mo-O-Mo network. The addition of the conducting polymer phase increases both the electrical conductivity (4 x 10-3 S/cm) and the lithium capacity (1.7 Li/Mo) compared to that of MoO3 aerogels. The third study emphasizes the use of the "sticky carbon" electrode to study the effects of high surface area and pore size on the lithium intercalation properties of V2O5 aerogels. A series of V2O 5 aerogels with varying surface areas (10 to 280 m2/g) is prepared through the ambient drying process for this study. The sticky carbon method, combined with the open structure of the aerogel, allow better lithium ion accessibility to the V2O5 aerogel cathode, leading to a much higher lithium capacity (˜6 Li/V2O5 ) compared to using the traditional composite cathode (3--4 LiV 2O5). A pseudocapacitive behavior (˜2000 F/g) is also observed in addition to the lithium intercalation.

Dong, Winny

79

Secondary lithium cells for space applications  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

80

Microstructure and electrochemical properties of a nanometer-scale tin anode for lithium secondary batteries  

NASA Astrophysics Data System (ADS)

The microstructure of nanometer-scale tin powder synthesized by the wire electric explosion (WEE) method is examined by transmission electron microscopy (TEM) at different Li insertion states, and then electrochemical properties of the tin power electrode are characterized by galvanostatic charge-discharge experiments. It is found that several Li/Sn inter-metalic compounds are formed during lithium insertion, namely Li 1- xSn, L 13Sn 5 and Li 7Sn 2. The passivation layer (or solid electrolyte interface, SEI) on the surface of particles cycled in an organic electrolyte electrochemical cell is characterized as Li 2CO 3 and ROCO 2Li by FT-IR spectroscopy. A great part of the passivation layer is amorphous, but a small is poorly crystallized.

Choi, Wanuk; Lee, Jeong Yong; Jung, Bok Hwan; Lim, Hong Sup

81

Organic electrolyte for use in a lithium rechargeable electrochemical cell and lithium rechargeable electrochemical cell including said organic electrolyte  

Microsoft Academic Search

This invention relates in general to use of an organic electrolyte in a lithium rechargeable electrochemical cell and to a lithium rechargeable electrochemical cell including said electrolyte; and, in particular, to the use of 1 to 2 mol\\/dm³ LiAsFâ in dimethylcarbonate (DMC) or 1 to 2 mol\\/dm³ LiAsFâ in (DMC) mixtures with methyl formate (MF) in which the mass percent

E. J. Plichta; S. M. Slane; M. Salomon

1987-01-01

82

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

83

Solid state polymer light-emitting electrochemical cells: Recent developments  

Microsoft Academic Search

Solid state polymer light-emitting electrochemical cells (LECs) offer a new approach to light-emitting devices fabricated from luminescent conjugated polymers. In LECs, the conjugated polymers are electrochemically p-doped near the anode side and n-doped near the cathode side; a light emitting p-n junction is formed between the doped regions. The admixed solid electrolyte provides the necessary ionic conductivity and dopant ions.

Q. Pei; Y. Yang; G. Yu; Y. Cao; A. J. Heeger

1997-01-01

84

Electrolyte for use in high energy lithium based rechargeable electrochemical cell and rechargeable electrochemical cell including the electrolyte  

Microsoft Academic Search

The general object of this invention is to provide a lithium based rechargeable electrochemical cell having an improved capacity. A more specific object of the invention is to provide an electrolyte for such a cell. A still further object of the invention is to provide such a cell. A still further object of the invention is to provide such a

R. J. Mammone; M. Binder

1986-01-01

85

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

86

Optimization of parameters of an electrochemical photovoltaic regenerative solar cell  

Microsoft Academic Search

Optimization of physical and geometrical parameters of an electrochemical photovoltaic regenerative solar cell with current leads located on opposite sides of a cell unit was studied. The dependence of local current density on the length co-ordinate is expressed using dimensionless quantities. A linear polarisation curve was assumed. The equation for maximal output in Watts per total unit surface area was

Ivo Roušar; Miroslav Rudolf; Petr Lukášek; Ladislav Kavan; Nicholas Papageorgiou; Michael Grätzel

1996-01-01

87

Mass transfer rates in a DEM electrochemical cell  

Microsoft Academic Search

The mass transfer characteristics of a DEM electrochemical cell were studied in both the presence and absence of a Netlon plastic mesh turbulence promotor. Two different modes of operation were used, one with a divided and the other with an undivided cell. Mass transfer coefficients were determined using the limiting current technique, with the cathodic reduction of potassium ferricyanide ion

W. M Taama; R. E. Plimley; K. Scott

1996-01-01

88

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

89

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

90

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

91

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

92

Method of making an electrochemical sensing cell  

SciTech Connect

An in vivo electrochemical monitoring device is formed by a catheter-like member which terminates in a closed end having a wall with a fixed opening to admit fluid to be tested, such as blood in an artery. An electrochemical sensor, such as an ISFET device for monitoring the concentration of a particular ion in blood, is mounted inside the tube at a fixed location below the opening preferably a larger sensing chamber. An infusion channel in the tube is arranged to flood the sensor with a fluid of known chemical properties so that the sensor output can be calibrated. Under pressure the calibration fluid expels the test fluid out of the tube or chamber via the fixed opening. A method of constructing a suitable chamber on an ISFET wafer is also disclosed.

Koning, G.; Bergveld, P.

1985-08-13

93

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

94

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

95

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

96

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

PubMed

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

2012-07-17

97

Investigation of Sickle-Cell Haemoglobin Polymerisation under Electrochemical Control  

PubMed Central

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

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

2013-01-01

98

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

99

Microfabricated Microbial Fuel Cell Arrays Reveal Electrochemically Active Microbes  

Microsoft Academic Search

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

Huijie Hou; Lei Li; Younghak Cho; Paul de Figueiredo; Arum Han; Debbie Fox

2009-01-01

100

Electrochemical cells having a gelled anode-electrolyte mixture  

Microsoft Academic Search

A method is described for improving the discharge characteristics of an electrochemical cell having a cathode, a powdered metal anode and an aqueous alkaline electrolyte solution comprising the step of gelling an intimate mixture of the powdered metal anode and electrolyte solution with an agent. The agent comprises a material capable of absorbing water and having a carbohydrate backbone and

T. O. Graham; J. T. Goodman

1987-01-01

101

Microfabricated Microbial Fuel Cell Arrays Reveal Electrochemically Active Microbes  

Microsoft Academic Search

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

Huijie Hou; Lei Li; Younghak Cho; Paul de Figueiredo; Arum Han

2009-01-01

102

Lithium electrochemical cell containing diethylcarbonate as an electrolyte solvent additive  

Microsoft Academic Search

The general object of this invention is to provide an improved lithium electrochemical cell, including lithium and cobalt oxide as the cathode active material. Other light metals or composites may be applicable as the anode such as sodium, potassium and aluminum, or any conductively doped polymeric material or similar compound. Moreover, the positive electrode or cathode may be any oxide,

E. J. Plichta; S. M. Slane

1988-01-01

103

Oxide modified air electrode surface for high temperature electrochemical cells  

DOEpatents

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

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

1992-01-01

104

Facile and quantitative electrochemical detection of yeast cell apoptosis  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

105

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

106

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

107

Corner heating in rectangular solid oxide electrochemical cell generators  

DOEpatents

Disclosed is an improvement in a solid oxide electrochemical cell generator 1 having a rectangular design with four sides that meet at corners, and containing multiplicity of electrically connected fuel cells 11, where a fuel gas is passed over one side of said cells and an oxygen containing gas is passed into said cells, and said fuel is burned to form heat, electricity, and an exhaust gas. The improvement comprises passing the exhaust gases over the multiplicity of cells 11 in such a way that more of the heat in said exhaust gases flows at the corners of the generator, such as through channels 19.

Reichner, Philip (Plum Boro, PA)

1989-01-01

108

Testing and analyses of electrochemical cells using frequency response  

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

109

New Family of Electrochemical Cells for NOx Decomposition with Multi Layer Electro-Catalytic Electrode  

Microsoft Academic Search

A new family of electrochemical cells for NO decomposition in the presence of 10% oxygen has been designed and investigated. A strong correlation between the process of NO decomposition and the microstructure and composition of the electro-catalytic electrode was observed. The ambipolar transport properties of the composite electro-catalytic electrode and the electrochemical properties of an electrochemical cell for NO decomposition

S. Bredikhin; A. Aronin; G. Abrosimova; K. Matsuda; M. Awano

2002-01-01

110

Development of Electrochemical Photovoltaic Cells. Third Technical Progress Report, November 1, 1979-January 31, 1980.  

National Technical Information Service (NTIS)

The development of stable, efficient, electrochemical photovoltaic cells based on silicon and gallium arsenide in non-aqueous electrolyte systems is being investigated. The effect of surface condition of silicon electrodes on electrochemical and physical ...

H. J. Byker R. E. Schwerzel V. E. Wood A. E. Austin E. W. Brooman

1980-01-01

111

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

112

Elastomers bonded to metal surfaces seal electrochemical cells  

NASA Technical Reports Server (NTRS)

A leakproof seal secondary cell containing alkaline electrolytes was developed by bonding an alkali-resistant elastomer, such as neoprene, to metal contact surfaces. Test results of several different elastomers strongly indicate the feasibility of this sealing method.

Sherfey, J. M.

1964-01-01

113

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

114

Electrochemical As(III) whole-cell based biochip sensor.  

PubMed

The development of a whole-cell based sensor for arsenite detection coupling biological engineering and electrochemical techniques is presented. This strategy takes advantage of the natural Escherichia coli resistance mechanism against toxic arsenic species, such as arsenite, which consists of the selective intracellular recognition of arsenite and its pumping out from the cell. A whole-cell based biosensor can be produced by coupling the intracellular recognition of arsenite to the generation of an electrochemical signal. Hereto, E. coli was equipped with a genetic circuit in which synthesis of beta-galactosidase is under control of the arsenite-derepressable arsR-promoter. The E. coli reporter strain was filled in a microchip containing 16 independent electrochemical cells (i.e. two-electrode cell), which was then employed for analysis of tap and groundwater samples. The developed arsenic-sensitive electrochemical biochip is easy to use and outperforms state-of-the-art bacterial bioreporters assays specifically in its simplicity and response time, while keeping a very good limit of detection in tap water, i.e. 0.8ppb. Additionally, a very good linear response in the ranges of concentration tested (0.94ppb to 3.75ppb, R(2)=0.9975 and 3.75 ppb to 30ppb, R(2)=0.9991) was obtained, complying perfectly with the acceptable arsenic concentration limits defined by the World Health Organization for drinking water samples (i.e. 10ppb). Therefore, the proposed assay provides a very good alternative for the portable quantification of As (III) in water as corroborated by the analysis of natural groundwater samples from Swiss mountains, which showed a very good agreement with the results obtained by atomic absorption spectroscopy. PMID:23584229

Cortés-Salazar, Fernando; Beggah, Siham; van der Meer, Jan Roelof; Girault, Hubert H

2013-09-15

115

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

116

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

117

Electrochemical H\\/D isotope effects in PEM fuel cell  

Microsoft Academic Search

An electrochemical H\\/D separation system consisting of electrolyzer and PEM fuel cell has been proposed. Isotope separation could be important as a part of the energy saving process in an energy-hydrogen-energy cycle. Any transfer of energy into hydrogen or vice versa induces change of the H\\/D isotope ratio, which can be considered, as a method to produce heavy water as

Milica P. Marceta Kaninski; Vladimir M. Nikolic; Aleksandar D. Maksic; Gvozden S. Tasic; Scepan S. Miljanic

2008-01-01

118

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

119

Lithium/sulfuryl chloride electrochemical cell  

SciTech Connect

The development of a practical sulfuryl chloride-based lithium/oxyhalide cell has been delayed by anode-corrosion and cathode-polarization problems. The anode-stability problem can be significantly alleviated by the use of a reverse-polarity cell design, the substitution of Li2B10Cl10 for LiAlCl4 as the electrolyte salt, and the addition of a suitable cosolvent (SO2 or SOCl2). Under ambient-temperature storage and discharge conditions, anode passivation is completely absent with hermetically sealed Li/SO2Cl2 cells of this type. Cathode polarization can be reduced by a supported-platinum material. This material also results in substantially increased discharge capacities, although the overall reaction stoichiometry is unaffected by the catalyst. Finally, SO2Cl2 thermal decomposition measurements indicate that, as the temperature of the SO2Cl2 in a hermetic cell is increased from 25 to 80 C, the pressure differential across the cell case rises to about 3.5 atm. As the temperature is decreased, the pressure differential decreases to an equilibrium value, indicating a thermally stable, reversible system. 20 references.

Klinedinst, K.A.

1984-03-01

120

Design and applications of an in situ electrochemical NMR cell.  

PubMed

A device using a three-electrode electrochemical cell (referred to as an ECNMR cell) was successfully constructed that could be used in a standard 5mm NMR probe to acquire high-resolution NMR spectra while the working electrode was held at a constant electrical potential. The working electrode was a 20 nm thick gold film thermally coated on the outside of an inner 3mm glass tube. An underlayer consisting of (3-mercaptopropyl)trimethoxy-silane was coated on the glass surface in order to improve its adhesion to gold. Tests showed prolonged life of the gold film. Details of the design and construction of the ECNMR cell are described. The ECNMR cell could be routinely used in a multi-user service high-resolution NMR instrument under oxygen-free conditions in both aqueous and non-aqueous solvents. Different approaches were applied to suppress the noise transmitted between the potentiostat and the NMR spectrometer. These approaches were shown to be effective in reducing background noise in the NMR spectra. The electrochemical and NMR performance of the ECNMR cell is presented. The reduction of 1,4-benzoquinone in both aqueous and non-aqueous solvents was used for testing. The evolution of the in situ ECNMR spectra with time demonstrated that use of the ECNMR cell was feasible. Studies of caffeic acid and 9-chloroanthracene using this ECNMR cell were undertaken to explore its applications, such as monitoring reactions and studying their reaction mechanisms. PMID:21067948

Zhang, Xiaocan; Zwanziger, Josef W

2011-01-01

121

Design and applications of an in situ electrochemical NMR cell  

NASA Astrophysics Data System (ADS)

A device using a three-electrode electrochemical cell (referred to as an ECNMR cell) was successfully constructed that could be used in a standard 5 mm NMR probe to acquire high-resolution NMR spectra while the working electrode was held at a constant electrical potential. The working electrode was a 20 nm thick gold film thermally coated on the outside of an inner 3 mm glass tube. An underlayer consisting of (3-mercaptopropyl)trimethoxy-silane was coated on the glass surface in order to improve its adhesion to gold. Tests showed prolonged life of the gold film. Details of the design and construction of the ECNMR cell are described. The ECNMR cell could be routinely used in a multi-user service high-resolution NMR instrument under oxygen-free conditions in both aqueous and non-aqueous solvents. Different approaches were applied to suppress the noise transmitted between the potentiostat and the NMR spectrometer. These approaches were shown to be effective in reducing background noise in the NMR spectra. The electrochemical and NMR performance of the ECNMR cell is presented. The reduction of 1,4-benzoquinone in both aqueous and non-aqueous solvents was used for testing. The evolution of the in situ ECNMR spectra with time demonstrated that use of the ECNMR cell was feasible. Studies of caffeic acid and 9-chloroanthracene using this ECNMR cell were undertaken to explore its applications, such as monitoring reactions and studying their reaction mechanisms.

Zhang, Xiaocan; Zwanziger, Josef W.

2011-01-01

122

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

123

Co-laminar flow cells for electrochemical energy conversion  

NASA Astrophysics Data System (ADS)

In this review, we present the major developments in the evolution of ‘membraneless’ microfluidic electrochemical cells which utilize co-laminar flow to minimize reactant mixing while producing electrical power in a compact form. Categorization of devices according to reactant phases is suggested, with further differentiation being subject to fabrication method and function, namely multi-layer sandwich structures for medium-power cell stacks and single-layer monolithic cells for low-power on-chip applications. Power density metrics reveal that recent co-laminar flow cells compare favourably with conventional membrane-based electrochemical cells and that further optimization of device architecture could be expedited through standardized testing. Current research trends indicate that co-laminar flow cell technology for power generation is growing rapidly and finding additional use as an analytical and education tool. Practical directions and recommendations for further research are provided, with the intention to guide scientific advances and technology development toward ultimate pairing with commercial applications.

Goulet, Marc-Antoni; Kjeang, Erik

124

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

125

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

126

Electrochemical hydrogen concentrator for phosphoric acid fuel cells  

NASA Astrophysics Data System (ADS)

The production of high purity hydrogen for use in phosphoric acid fuel cell from heavily contaminated reformed diesel fuel gas using an electrochemical device has been demonstrated. The electrochemical hydrogen separator (EHS) is based on current PAFC technology. Hydrogen is removed from the contaminated gas stream by oxidation to hydrogen ions at a gas diffusion cathode. An anode catalyst with excellent tolerance to high levels of CO and H2S contaminants has been developed. The use of this anode catalyst would allow the EHS device to produce pure hydrogen with minimal voltage impact on the overall PAFC power output. Reduction in size and weight of the PAFC power plant is also indicated through reduced load on fuel processing components.

Giner, Jose; Kackley, Nancy D.

1987-11-01

127

Electrochemical cell with high discharge/charge rate capability  

DOEpatents

A fully charged positive electrode composition for an electrochemical cell includes FeS.sub.2 and NiS.sub.2 in about equal molar amounts along with about 2-20 mole percent of the reaction product Li.sub.2 S. Through selection of appropriate electrolyte compositions, high power output or low operating temperatures can be obtained. The cell includes a substantially constant electrode impedance through most of its charge and discharge range. Exceptionally high discharge rates and overcharge protection are obtainable through use of the inventive electrode composition.

Redey, Laszlo (Downers Grove, IL)

1988-01-01

128

Electrochemical cell with high discharge/charge rate capability  

NASA Astrophysics Data System (ADS)

A fully charged positive electrode composition for an electrochemical cell includes FeS2 and NiS2 in about equal molar amounts along with about 2 to 20 mole % of the reaction product Li2S. Through selection of appropriate electrolyte compositions, high power output or low operating temperatures can be obtained. The cell includes a substantially constant electrode impedance through most of its charge and discharge range. Exceptionally high discharge rates and overcharge protection are obtainable through use of the inventive electrode composition.

Redey, L.

1986-07-01

129

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

130

Plant cell cultures: Chemical factories of secondary metabolites  

Microsoft Academic Search

This review deals with the production of high-value secondary metabolites including pharmaceuticals and food additives through plant cell cultures, shoot cultures, root cultures and transgenic roots obtained through biotechnological means. Plant cell and transgenic hairy root cultures are promising potential alternative sources for the production of high-value secondary metabolites of industrial importance. Recent developments in transgenic research have opened up

S Ramachandra Rao; G. A Ravishankar

2002-01-01

131

Parenchyma cells of secondary phloem in Pinus strobus  

Microsoft Academic Search

Parenchyma cells of the secondary phloem in Pinus strobus have all the cellular organelles common in other plant cells. They have mitochondria, endoplasmic reticulum, ribosomes, dictyosomes, and plastids. Parenchyma cells are very conspicuous because of their organic inclusions, starch and lipids. Plasmodesmata in transverse and tangential walls of axial parenchyma cells and in end walls of ray parenchyma cells are

Lidija Murmanis; Ray F. Evert

1967-01-01

132

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

133

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. 5 figs.

Jensen, R.R.

1990-11-20

134

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

135

Secondary Lithium Cells for Space Applications.  

National Technical Information Service (NTIS)

It is concluded that secondary lithium batteries are suitable for planetary missions requiring high specific energy, long active shelf life, and limited cycle life. Titanium disulfide cathode material meet all the requirements for rechargeable lithium cel...

S. Surampudi D. H. Shen C. Huang S. R. Narayanan A. Attia

1992-01-01

136

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

137

Multiscale Simulation of Electrochemical_/ Phenomena: Fuel Cells and Batteries  

NASA Astrophysics Data System (ADS)

Results will be presented from multiscale simulations of two important systems from renewable energy technology, fuel cell proton membranes and electrochemical cells. In the first case, the solvation and transport of hydrated protons in proton exchange membranes (PEMs) such as Nafion^TM will be described using a novel multi-state reactive molecular dynamics (MD) approach. The multi-state MD methodology allows for the treatment of explicit (Grotthuss) proton shuttling and charge defect delocalization which, in turn, can strongly influence the properties of the hydrated protons in various aqueous and complex environments. The role of PEM hydration level and morphology on these properties will be further described. A new multiscale computational methodology for describing the mesoscopic features of the proton transport will also be described, which can be coupled to the results from the molecular-scale simulations. On the second topic, a computationally efficient method will be presented for the treatment of electrostatic interactions between polarizable metallic electrodes held at a constant potential and separated by an electrolyte. The method combines a fluctuating uniform electrode charge with explicit image charges to account for the polarization of the electrode by the electrolyte, and a constant uniform charge added to the fluctuating uniform electrode charge to account for the constant potential condition. The method is used to calculate electron transport rates using electron transfer theory; these rates are incorporated in a multiscale approach to model oxidation/reduction reactions in an electrochemical cell efficiently.

Voth, Gregory

2012-02-01

138

Electrodes for Electrochemical Supercapacitors  

Microsoft Academic Search

Manganese dioxide nanoparticles were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors (ES) were fabricated by impregnation of slurries of the manganese dioxide nanoparticles and carbon black into porous nickel foam current collectors. In the composite electrodes, carbon black nanoparticles formed a secondary conductivity network within the nickel foam cells. Obtained composite electrodes, containing manganese dioxide and

Gideon Moses Jacob; Quan Min Yang; Igor Zhitomirsky

2009-01-01

139

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.

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

140

Scanning electrochemical microscopy of menadione-glutathione conjugate export from yeast cells  

Microsoft Academic Search

The uptake of menadione (2-methyl-1,4-naphthoquinone), which is toxic to yeast cells, and its expulsion as a glutathione complex were studied by scanning electrochemical microscopy. The progression of the in vitro reaction between menadione and glutathione was monitored electrochemically by cyclic voltammetry and correlated with the spectroscopic (UV-visible) behavior. By observing the scanning electrochemical microscope tip current of yeast cells suspended

Janine Mauzeroll; Allen J. Bard

2004-01-01

141

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

142

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

143

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

144

Microstructure and electrochemical properties of a nanometer-scale tin anode for lithium secondary batteries  

Microsoft Academic Search

The microstructure of nanometer-scale tin powder synthesized by the wire electric explosion (WEE) method is examined by transmission electron microscopy (TEM) at different Li insertion states, and then electrochemical properties of the tin power electrode are characterized by galvanostatic charge–discharge experiments. It is found that several Li\\/Sn inter-metalic compounds are formed during lithium insertion, namely Li1?xSn, L13Sn5 and Li7Sn2. The

Wanuk Choi; Jeong Yong Lee; Bok Hwan Jung; Hong Sup Lim

2004-01-01

145

Photocurrent generation in an electrochemical cell with substituted metalloporphyrins  

NASA Astrophysics Data System (ADS)

Photocurrent generation in a semiconducting-metallic electrochemical cell filled with metallotetraphenyloporphyrins dissolved in polyvinylalcohol and metallotetranaphthyloporphyrins in nematic liquid crystal was investigated. The photopotential action spectra showed that the dye molecules are responsible for photoresponse. It has been shown that the intensity of photocurrent was dependent on the type of central metal complexed with the porphyrin ring of the dye molecule and also on the substituents attached to the methine bridge. The dependencies of the photopotential signal and of incident light-photosignal phase shift as a function of modulation light frequency indicate that the observed effect is due to more than one mechanism of electron transport. The results for metalloporphyrin dyes in fluid polyvinylalcohol and in nematic liquid crystal (D. Wróbel, J. Goc, R.M. Ion, J. Mol. Struct. 450 (1998) 239) were compared. The reasons of the different effectiveness of photoresponse in the electrochemical cell with different porphyrins complexed with various metals and substituted by different functional groups are discussed.

Wróbel, D.; ?ukasiewicz, J.; Goc, J.; Waszkowiak, A.; Ion, R.

2000-11-01

146

Lithium Electrochemical Cell Including Aprotic Solvent-Dialkyl Carbonate Solvent Mixture.  

National Technical Information Service (NTIS)

This invention relates in general to a lithium electrochemical cell and in particular, to a lithium electrochemical cell including lithium as the anode, non-stoichiometric (ns)-V6013 as the cathode, and a solution and a solution of lithium salt in a mixed...

S. M. Slane E. J. Plichta M. Salomon M. C. Uchiyama

1987-01-01

147

Electrochemical impedance spectroscopy of lithium-titanium disulfide rechargeable cells  

SciTech Connect

The two-terminal alternating current impedance of lithium-titanium disulfide (Li/TiS[sub 2]) rechargeable cells has been studies as a function of frequency, state-of-charge, and extended cycling. Analysis based on a plausible equivalent circuit model for the Li/TiS[sub 2] cell leads to evaluation of kinetic parameters for the various physicochemical processes occurring at the electrode/electrolyte interfaces. To investigate the causes of cell degradation during extended cycling, the parameters evaluated for cells cycled five times have been compared with the parameters of cells that have been cycled over 600 times. The findings are that the combined ohmic resistance of the electrolyte and electrodes suffers a ten-fold increase after extended cycling, while the charge-transfer resistance and diffusional impedance at the TiS[sub 2]/electrolyte interface are not significantly affected. The results reflect the morphological change and increase in area of the anode due to cycling. The study also shows that overdischarge of a cathode-limited cell causes a decrease in the diffusion coefficient of the lithium ion in the cathode. The study demonstrate the value of electrochemical impedance spectroscopy in investigating failure mechanisms. The approach and methodology followed here can be extended to other rechargeable lithium battery system.

Narayanan, S.R.; Shen, D.H.; Surampudi, S.; Attia, A.I.; Halpert, G. (California Inst. of Technology, Pasadena, CA (United States). Jet Propulsion Lab.)

1993-07-01

148

Mechanical and electrochemical characterization of intermediate temperature micro-tubular solid oxide fuel cell  

NASA Astrophysics Data System (ADS)

Solid oxide fuel cells (SOFCs) are attributed for being highly efficient in their energy conversion capabilities and fuel flexibility. The primary objective of this study was to develop an operating solid oxide fuel cell using innovative and cost-effective fabrication techniques. The secondary objective of this research aimed at improving mechanical and electrochemical properties of the cell through utilization of electrode materials characterized by different morphology. The system studied was a micro-tubular, anode supported SOFC operated on both hydrogen and internally-reformed methane at the temperature range of 800-850°C. The research studied different anode poreformers and the utilization of anode powders with different morphologies. Anode supports, fabricated using an extrusion process, were based on a standard composition of 50/50 vol% of NiO/8YSZ powder. Procedures were developed to deposit a 2-5 mum thin and dense 8YSZ electrolyte film via a quick and cost-effective vacuum infiltration process. Two different materials were utilized to fabricate anode supports. The first anode powder consisted of small, nano-size, particles, while the second powder was a sub-micron size powder. Vastly improved power density and redox cycling results were observed from a fuel cell fabricated using a fine powder. For example a power density of >0.5 W cm-2 at 800°C was observed. The performance data of an SOFC operating on internally-reformed methane is presented. A response of the fuel cell set up using two different sealing designs, a cold-seal design and a hot-seal design, is also explained. The electrochemical activity of Gd0.5Sr0.5CoO 3-x cathode fabricated using a standard glycine-nitrate pyrolysis technique and a technique allowing direct deposition of cathode material on top of electrolyte powder was tested. The thesis concludes with recommendations for further work.

Pusz, Jakub

149

Plant cell cultures: Chemical factories of secondary metabolites.  

PubMed

This review deals with the production of high-value secondary metabolites including pharmaceuticals and food additives through plant cell cultures, shoot cultures, root cultures and transgenic roots obtained through biotechnological means. Plant cell and transgenic hairy root cultures are promising potential alternative sources for the production of high-value secondary metabolites of industrial importance. Recent developments in transgenic research have opened up the possibility of the metabolic engineering of biosynthetic pathways to produce high-value secondary metabolites. The production of the pungent food additive capsaicin, the natural colour anthocyanin and the natural flavour vanillin is described in detail. PMID:14538059

Rao, S R; Ravishankar, G A

2002-05-01

150

Definition of Chemical and Electrochemical Properties of a Fuel Cell Electrolyte.  

National Technical Information Service (NTIS)

The present research is oriented toward the task of developing an improved electrolyte for the direct hydrocarbon-air fuel cell. The electrochemical behavior of methanesulfonic acid, ethanesulfonic acid, and sulfoacetic acid as fuel cell electrolytes was ...

J. Ahmad R. T. Foley

1980-01-01

151

Suppressing The Growth Of Dendrites In Secondary Li Cells  

NASA Technical Reports Server (NTRS)

Proposed technique for suppressing growth of lithium dendrites in rechargeable lithium electrochemical power cells involves periodic interruption of steady charging current with short, high-current discharge pulses. Technique applicable to lithium cells of several different types, including Li/TiS(2), Li/NbSe(3), Li/CoO(2), Li/MoS(2), Li/Vo(x), and Li/MnO(2). Cells candidates for use in spacecraft, military, communications, automotive, and other applications in which high-energy-density rechargeable batteries needed.

Davies, Evan D.; Perrone, David E.; Shen, David H.

1996-01-01

152

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

153

Phthalocyanine cathode materials for secondary lithium cells  

SciTech Connect

Discharge and charge characteristics of various phthalocyanine cathodes coupled with lithium metal are studied. The best capacity based only on cathode active material weight is 1440 A-hr/kg in the lithium/iron phthalocyanine system, and the cycle life of the lithium/Cu phthalocyanine system is more than 100 times at the discharge depth of 157 A-hr/kg. The cathode reaction mechanism is supposed to be lithium intercalation between phthalocyanine molecules. The results indicate that these phthalocyanines are promising cathode active materials for lithium secondary batteries. 15 refs.

Yamaki, J.; Yamaji, A.

1982-01-01

154

Phthalocyanine cathode materials for secondary lithium cells  

SciTech Connect

Discharge and charge characteristics of various phthalocyanine cathodes coupled with lithium metal are studied. The best capacity based only on cathode active material weight is 1440 A-hr/kg in the lithium/iron phthalocyanine system, and the cycle life of the lithium/Cu phthalocyanine system is more than 100 times at the discharge depth of 157 A-hr/kg. The cathode reaction mechanism is supposed to be lithium intercalation between phthalocyanine molecules. The results indicate that these phthalocyanines are promising cathode active materials for lithium secondary batteries.

Tamaki, J.; Yamaji, A.

1982-01-01

155

Stabilizing metal components in electrodes of electrochemical cells  

SciTech Connect

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

156

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

157

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

158

Interfacial phenomena observed in electrochemical systems (lithium-ion batteries, fuel cells, dye sensitized solar cells); causes, relevance and enhancements  

Microsoft Academic Search

This dissertation is aimed to understand the interfacial phenomena in electrochemical systems. Three electrochemical systems, namely, Lithium Ion Batteries, Fuel Cells and Dye Sensitized Solar Cells were chosen to elucidate the different type of the interfaces involved. In Lithium ion batteries the interface between an electrode and an electrolyte called as the solid electrolyte interface plays an important role in

Shabab Amiruddin

2008-01-01

159

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

160

Electrochemical cell system for voltammetry of high purity solvents  

NASA Astrophysics Data System (ADS)

A two-compartment cell system was designed to carry out high purity electrochemical experiments. Features of this cell include a monolithic quartz body, quartz isolation frit, pretreated platinum electrode, hydrogen reference electrode, snap-on cell tops, purified ``type I'' water, high purity supply gases, fluoropolymer tubing, and gas-tight cell integrity. An advantage of this design is the allowance for internal pre-electrolysis of the test solution. The system was quality tested by obtaining cyclic voltammograms of 0.5 molar sulfuric acid solution. To demonstrate its utility for high purity work, novel cyclic voltammograms of type I water were obtained with a platinum microelectrode in the absence of electrolyte. The water voltammograms exhibited three electroactive features: reduction potential limit near E=-0.2 V versus r.h.e. (H2), oxidation potential limit near E=+1.6 V (O2), and one surface reduction peak at E=+0.4 V. Thus, the voltammetric ``potential window'' for water was determined to be 1.8 V.

May, Michael A.; Gupta, Vijay K.; Hounsokou, Karen

2000-02-01

161

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

162

Nanopillar based electrochemical biosensor for monitoring microfluidic based cell culture  

NASA Astrophysics Data System (ADS)

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

Gangadharan, Rajan

163

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

DOEpatents

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

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

2003-05-27

164

Life Testing of Secondary Ag-Zn Cells.  

National Technical Information Service (NTIS)

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 a...

J. C. Brewer R. Doreswamy

1991-01-01

165

THERMAL-ELECTROCHEMICAL COUPLED MODELING OF A LITHIUM-ION CELL  

Microsoft Academic Search

A multi-dimensional thermal and electrochemical coupled model is developed for Li-ion batteries. The model is capable of predicting the cell internal temperature distribution as well as the average cell temperature evolution. Numerical simulations are performed for a large-size Li-ion cell for electric vehicle applications. Comparisons between the coupled and decoupled model predictions indicate the importance of thermal- electrochemical coupling for

W. B. Gu; C. Y. Wang

1999-01-01

166

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

167

Electrochemical Methods for Catalyst Evaluation in Fuel Cells and Solar Cells  

Microsoft Academic Search

In this chapter, electrochemical methods for the catalyst research for fuel cells, charge transport in electrode reaction,\\u000a and heterogeneous charge transport are presented and discussed with some examples of data measurements and analyses. In fuel\\u000a cell research and development, the most utilized tools for the oxygen reduction reaction (cathode reaction) are the rotating\\u000a disk and rotating ring-disk electrodes in a

T. Okada; M. Kaneko

168

Photocured Gelled Electrolytes For Secondary Li Cells  

NASA Technical Reports Server (NTRS)

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

Nagasubramanian, Ganesan

1994-01-01

169

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

170

Circuit prevents overcharging of secondary cell batteries  

NASA Technical Reports Server (NTRS)

Circuit prevents battery cell overcharging by detecting and reducing the charging voltage to the open-circuit voltage of the battery when this current falls to a predetermined value. The voltage control depends on the fact that the charging current falls significantly when the battery nears its fully charged state.

Hennigan, T. J.; Potter, N. H.; Sizemore, K. O.

1966-01-01

171

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

172

Support tube for high temperature solid electrolyte electrochemical cell  

DOEpatents

Disclosed is a compound having a fluorite-like structure comprising a solid solution having the general formula [(ZrO.sub.2).sub.1-x (MO.sub.s).sub.x ].sub.1-y [(La.sub.m A.sub.1-m).sub.2-z (Mn.sub.n B.sub.1-n).sub.z O.sub.r ].sub.y where MO.sub.5 is an oxide selected from the group consisting of calcia, yttria, rare earth oxides, and mixtures thereof, x is about 0.1 to 0.3, y is about 0.005 to about 0.06, z is about 0.1 to about 1.9, A is yttrium, rare earth element, alkaline earth element, or mixture thereof, B is iron, nickel, cobalt, or mixture thereof, m is 0.3 to 1, n is 0.5 to 1, and r is 2 to 4. A porous tube made from such a composition can be coated with an electrically conducting mixed oxide electrode such as lanthanum manganite, and can be used in making high temperature electrochemical cells such as solid electrolyte fuel cells.

Ruka, Roswell J. (Churchill Boro, PA); Rossing, Barry R. (Pittsburgh, PA)

1986-01-01

173

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

174

Evolutionary diversification of secondary mechanoreceptor cells in tunicata  

PubMed Central

Background Hair cells are vertebrate secondary sensory cells located in the ear and in the lateral line organ. Until recently, these cells were considered to be mechanoreceptors exclusively found in vertebrates that evolved within this group. Evidence of secondary mechanoreceptors in some tunicates, the proposed sister group of vertebrates, has recently led to the hypothesis that vertebrate and tunicate secondary sensory cells share a common origin. Secondary sensory cells were described in detail in two tunicate groups, ascidians and thaliaceans, in which they constitute an oral sensory structure called the coronal organ. Among thaliaceans, the organ is absent in salps and it has been hypothesised that this condition is due to a different feeding system adopted by this group of animals. No information is available as to whether a comparable structure exists in the third group of tunicates, the appendicularians, although different sensory structures are known to be present in these animals. Results We studied the detailed morphology of appendicularian oral mechanoreceptors. Using light and electron microscopy we could demonstrate that the mechanosensory organ called the circumoral ring is composed of secondary sensory cells. We described the ultrastructure of the circumoral organ in two appendicularian species, Oikopleura dioica and Oikopleura albicans, and thus taxonomically completed the data collection of tunicate secondary sensory cells. To understand the evolution of secondary sensory cells in tunicates, we performed a cladistic analysis using morphological data. We constructed a matrix consisting of 19 characters derived from detailed ultrastructural studies in 16 tunicate species and used a cephalochordate and three vertebrate species as outgroups. Conclusions Our study clearly shows that the circumoral ring is the appendicularian homologue of the coronal organ of other tunicate taxa. The cladistic analysis enabled us to reconstruct the features of the putative ancestral hair cell in tunicates, represented by a simple monociliated cell. This cell successively differentiated into the current variety of oral mechanoreceptors in the various tunicate lineages. Finally, we demonstrated that the inferred evolutionary changes coincide with major transitions in the feeding strategies in each respective lineage.

2013-01-01

175

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

176

[Secondary plasma cell leukemia. Report of 2 cases].  

PubMed

Plasma cell leukemia is considered as the leukemic variant of multiple myeloma. It is a rare entity. There are two forms: a secondary one following a known myeloma, the diagnosis of which is easy, and a primary one arising without a preceding phase of multiple myeloma. The diagnosis of the latter form is more difficult, a differential diagnosis has often to be discussed with other lymphoproliferative diseases. Prognosis is poor. We report 2 cases of secondary plasma cell leukemia diagnosed over ten years, among 59 of multiple myeloma cases. We describe the epidemiologic, clinical, biological and evolutionary characteristics. PMID:16220704

Sondes, Mseddi; Choumous, Kallel; Moez, Elloumi; Naourez, Ajmi; Fatma, Ben Said; Faiza, Makni; Taoufik, Souissi

2005-07-01

177

Conversion and Storage in Electrochemical Photovoltaic Cells. Final Report, 15 September 1979-15 January 1985.  

National Technical Information Service (NTIS)

This research was undertaken to provide a better understanding of the parameters that must be controlled to make efficient electrochemical photovoltaic solar cells with inexpensive in situ energy storage. It has been demonstrated that reproducible, ''stab...

M. Tomkiewicz I. Ling W. S. Parson R. B. Silberstein J. K. Lyden

1985-01-01

178

Electrochemical Characteristics of Acid Electrolytes for Fuel Cells. Final Report, January 1, 1989-June 30, 1991.  

National Technical Information Service (NTIS)

The electrochemical evaluation of new perfluorinated fuel cell electrolytes provided by GRI contractors at Clemson and Iowa shows the kinetics for O2 reduction on Pt improves with these acids compared to with phosphoric acid. The improvement is mainly due...

D. Gervasio M. Razaq A. Razaq R. Adzic K. Kanamura

1992-01-01

179

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

SciTech Connect

An electrochemical in-situ reaction cell for hard X-ray experiments with battery electrodes is described. Applications include the small angle scattering, diffraction, and near-edge spectroscopy of lithium manganese oxide electrodes.

Braun, Artur; Granlund, Eric; Cairns, Elton J.

2003-01-27

180

Life testing of secondary Ag-Zn cells  

NASA Technical Reports Server (NTRS)

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

1991-01-01

181

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

182

Electrochemical investigations of lithium-aluminum alloy anode in Li\\/polymer cells  

Microsoft Academic Search

A first study demonstrating the electrochemical cyclability of the LiAl alloy anode in the Li\\/polymer cells reported was carried out using LiAl\\/PEO30-LiN(CF3SO2)2\\/V2O5 cells in which the cell capacities were limited by LiAl anode. The cells fabricated with LiAl anode exhibited excellent electrochemical performance. The coulombic efficiency throughout the cell cycling was also close to 100% indicating that the lithium dendrite

Hyun Joo Bang; Sanggu Kim; Jai Prakash

2001-01-01

183

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

SciTech Connect

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 preparation, introduces the unique electrochemical behavior of graphene, and summarizes the recent research and development on graphene-based fuel cells, supercapacitors and lithium ion batteries. In addition, promising areas are identified for the future development of graphene-based materials in electrochemical energy conversion and storage systems.

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

2011-09-14

184

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

185

Electrochemical concentration cell ozonesonde performance evaluation during STOIC 1989  

SciTech Connect

Electrochemical concentration cell (ECC) ozonesondes flown by NOAA and NASA Wallops Flight Facility (WFF) personnel during the Stratospheric Ozone Intercomparison Campaign (STOIC) conducted at the Jet Propulsion Laboratory`s Table Mountain Facility, Wrightwood, California, July 21 to August 1, 1989, exhibited highly similar ozone measurement precisions and accuracies even though considerably different methods were used by the two research groups in preparing the instruments for use and in calibrating the instruments. The Table Mountain data as well as data obtained in the past showed the precisions to range from about {plus_minus}3 to {plus_minus}12% in the troposphere, remain relatively constant at {plus_minus}3% in the stratosphere to 10 mbar, then decrease to about {plus_minus}10% at 4-mbar pressure altitude. Corresponding ozone measurement accuracies for individual ozonesonde sounding were estimated to be about {plus_minus}6% near the ground, decrease to {minus}7 to 17% in the high troposphere where ozone concentrations are low, increase to about {plus_minus}5% in the low stratosphere and remain so to an altitude of about 10 mbar ({approximately}32 km), then decrease to {minus}14 to 6% at 4 mbar ({approximately}38 km) where ozone concentrations are again low. Stratospheric ozone measurements were also made during STOIC with ground-based lidars and a microwave radiometer that will be used for ozone measurements in the future at sites of the Network for the Detection of Stratospheric Change (NDSC). The ECC ozonesonde observations provided useful comparison data for evaluating the performance of the lidar and microwave instruments. 29 refs., 8 figs., 3 tabs.

Komhyr, W.D. [NOAA Climate Monitoring and Diagnostics Lab., Boulder, CO (United States)] [NOAA Climate Monitoring and Diagnostics Lab., Boulder, CO (United States); [Univ. of Colorado, Boulder, CO (United States); Brothers, G.B.; Barns, R.A. [Chemal Incorporated, Wallops Island, VA (United States)] [and others] [Chemal Incorporated, Wallops Island, VA (United States); and others

1995-05-20

186

Ambient temperature secondary Li/FeS2 cells  

NASA Astrophysics Data System (ADS)

The natural pyrite mineral FeS2 is found to be at least a partially rechargeable cathode material. The study demonstrates 22 deep cycles in cells with 'practical' cathode capacity densities. The long-term rechargeability shown in high-temperature cells is considered to suggest the high cycle life and secondary properties of FeS2. The results establish the technical possibility of applying FeS2 as a high rate cathode material in primary lithium cells which contain lithium organoborate electrolytes.

Newman, G. H.; Klemann, L. P.

187

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

188

Simulations and study of electrochemical hydrogen energy conversion in EasyTest Cell  

Microsoft Academic Search

An EasyTest Cell concept is applied to study the performance characteristics of the electrochemical processor for polymer electrolyte membrane electrochemical hydrogen energy converters (PEM EHEC), broadly known as a membrane electrode assembly (MEA). A series of MEAs consisting of Nafion 117 polymer electrolyte and magnetron sputtered Pt, IrOx, and composite IrOx\\/Pt\\/IrOx catalysts with varying catalytic loadings were investigated. The partial

I. Radev; E. Slavcheva; E. Budevski; U. Schnakenberg

2009-01-01

189

VHDL-AMS model of an electrochemical cell to design VLSI bio-chips  

Microsoft Academic Search

This paper presents a new VHDL-AMS behavioral model of an electrochemical cell suitable for the design of VLSI bio-chips. Existing models are mainly equivalent circuit macro-models using electrical primitives, which hardly fit the actual behavior of biosensors. The presented VHDL-AMS model expresses a more realistic behavior as it can directly use electrochemical equations. It can also be made very flexible

Marialaura Beltrandi; Alain Vachoux; Sandro Carrara; Yusuf Leblebici; Giovanni De Micheli

2011-01-01

190

Electrochemical stability of carbon nanofibers in proton exchange membrane fuel cells  

Microsoft Academic Search

This fundamental study deals with the electrochemical stability of several non-conventional carbon based catalyst supports, intended for low temperature proton exchange membrane fuel cell (PEMFC) cathodes. Electrochemical surface oxidation of raw and functionalized carbon nanofibers, and carbon black for comparison, was studied following a potential step treatment at 25.0°C in acid electrolyte, which mimics the operating conditions of low temperature

Garbiñe Álvarez; Francisco Alcaide; Oscar Miguel; Pere L. Cabot; M. V. Martínez-Huerta; J. L. G. Fierro

2011-01-01

191

Electrochemical studies on niobium triselenide cathode material for lithium rechargeable cells  

Microsoft Academic Search

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

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

1989-01-01

192

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

SciTech Connect

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

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

1980-12-01

193

Secondary failure of platelet recovery after hematopoietic stem cell transplantation  

Microsoft Academic Search

After primary recovery of platelet counts after transplantation, there can be a late persistent decline called secondary failure of platelet recovery (SFPR), which may occur although the counts of other cell lineages remain within the normal range. SFPR was defined as a decline of platelet counts below 20,000\\/microL for 7 consecutive days or requiring transfusion support after achieving sustained platelet

Benedetto Bruno; Theodore Gooley; Keith M Sullivan; Chris Davis; William I Bensinger; Rainer Storb; Richard A Nash

2001-01-01

194

Toxicity of graphene nanoflakes evaluated by cell-based electrochemical impedance biosensing.  

PubMed

Graphene nanoflake toxicity was analyzed using cell-based electrochemical impedance biosensing with interdigitated indium tin oxide (ITO) electrodes installed in a custom-built mini- incubator positioned on an inverted optical microscope. Sensing with electrochemical measurements from interdigitated ITO electrodes was highly linear (R(2) ?=?0.93 and 0.96 for anodic peak current (Ipa ) and cathodic peak current (Ipc ), respectively). Size-dependent analysis of Graphene nanoflake toxicity was carried out in a mini-incubator system with cultured HeLa cells treated with Graphene nanoflakes having an average size of 80 or 30 nm for one day. Biological assays of cell proliferation and viability complemented electrochemical impedance measurements. The increased toxicity of smaller Graphene nanoflakes (30 nm) as measured by electrochemical impedance sensing and optical monitoring of treated cells was consistent with the biological assay results. Cell-based electrochemical impedance biosensing can be used to assess the toxicity of nanomaterials with different biomedical and environmental applications. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2288-2294, 2014. PMID:23894129

Yoon, Ok Ja; Kim, Insu; Sohn, Il Yung; Kieu, Truong Thuy; Lee, Nae-Eung

2014-07-01

195

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

SciTech Connect

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

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

2012-05-01

196

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

PubMed

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

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

2012-07-01

197

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.

2014-01-01

198

In situ solid-state NMR spectroscopy of electrochemical cells: batteries, supercapacitors, and fuel cells.  

PubMed

Electrochemical cells, in the form of batteries (or supercapacitors) and fuel cells, are efficient devices for energy storage and conversion. These devices show considerable promise for use in portable and static devices to power electronics and various modes of transport and to produce and store electricity both locally and on the grid. For example, high power and energy density lithium-ion batteries are being developed for use in hybrid electric vehicles where they improve the efficiency of fuel use and help to reduce greenhouse gas emissions. To gain insight into the chemical reactions involving the multiple components (electrodes, electrolytes, interfaces) in the electrochemical cells and to determine how cells operate and how they fail, researchers ideally should employ techniques that allow real-time characterization of the behavior of the cells under operating conditions. This Account reviews the recent use of in situ solid-state NMR spectroscopy, a technique that probes local structure and dynamics, to study these devices. In situ NMR studies of lithium-ion batteries are performed on the entire battery, by using a coin cell design, a flat sealed plastic bag, or a cylindrical cell. The battery is placed inside the NMR coil, leads are connected to a potentiostat, and the NMR spectra are recorded as a function of state of charge. (7)Li is used for many of these experiments because of its high sensitivity, straightforward spectral interpretation, and relevance to these devices. For example, (7)Li spectroscopy was used to detect intermediates formed during electrochemical cycling such as LixC and LiySiz species in batteries with carbon and silicon anodes, respectively. It was also used to observe and quantify the formation and growth of metallic lithium microstructures, which can cause short circuits and battery failure. This approach can be utilized to identify conditions that promote dendrite formation and whether different electrolytes and additives can help prevent dendrite formation. The in situ method was also applied to monitor (by (11)B NMR) electrochemical double-layer formation in supercapacitors in real time. Though this method is useful, it comes with challenges. The separation of the contributions from the different cell components in the NMR spectra is not trivial because of overlapping resonances. In addition, orientation-dependent NMR interactions, including the spatial- and orientation-dependent bulk magnetic susceptibility (BMS) effects, can lead to resonance broadening. Efforts to understand and mitigate these BMS effects are discussed in this Account. The in situ NMR investigation of fuel cells initially focused on the surface electrochemistry at the electrodes and the electrochemical oxidation of methanol and CO to CO2 on the Pt cathode. On the basis of the (13)C and (195)Pt NMR spectra of the adsorbates and electrodes, CO adsorbed on Pt and other reaction intermediates and complete oxidation products were detected and their mode of binding to the electrodes investigated. Appropriate design and engineering of the NMR hardware has allowed researchers to integrate intact direct methanol fuel cells into NMR probes. Chemical transformations of the circulating methanol could be followed and reaction intermediates could be detected in real time by either (2)H or (13)C NMR spectroscopy. By use of the in situ NMR approach, factors that control fuel cell performance, such as methanol cross over and catalyst performance, were identified. PMID:24041242

Blanc, Frédéric; Leskes, Michal; Grey, Clare P

2013-09-17

199

Mixed solvent electrolyte for high voltage lithium metal secondary cells  

Microsoft Academic Search

We have examined various solvents and solutes as electrolytes for high voltage lithium metal secondary cells in terms of the oxidation potential, specific conductivity and cycling performance of Li\\/LiMn1.9Co0.1O4 cells. We selected propylene carbonate (PC), ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), 1,2-dimethoxyethane (DME) and 1,2-diethoxyethane (DEE) as the solvents, and LiClO4, LiPF6, LiAsF4 and LiBF4 as the

Katsuya Hayashi; Yasue Nemoto; Shin-ichi Tobishima; Jun-ichi Yamaki

1999-01-01

200

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

DOEpatents

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

Reichner, Philip (Plum Boro, PA)

1988-01-01

201

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

202

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

Microsoft Academic Search

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

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

2011-01-01

203

Nanoparticle decorated anodes for enhanced current generation in microbial electrochemical cells  

Microsoft Academic Search

The development of highly efficient anode materials is critical for enhancing the current output of microbial electrochemical cells. In this study, Au and Pd nanoparticle decorated graphite anodes were developed and evaluated in a newly designed multi-anode microbial electrolysis cell (MEC). The anodes decorated with Au nanoparticles produced current densities up to 20-fold higher than plain graphite anodes by Shewanella

Yanzhen Fan; Shoutao Xu; Rebecca Schaller; Jun Jiao; Frank Chaplen; Hong Liu

2011-01-01

204

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

205

The effect of secondary impurities on solar cell performance  

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

206

Improved silver/zinc secondary cells for underwater applications  

NASA Astrophysics Data System (ADS)

Performance improvements in silver/zinc technology have been achieved with new developments in additives and separator coatings. These improvements, aimed at increasing the cycle life and energy density of silver/zinc cells, were realized through advances in the stateof the-art of the zinc electrode and of the separators, which are the major limitations to this electrochemical couple. To achieve these objectives, two basic approaches were employed: (i) the introduction of a new class of materials known as electro permeable membranes (EPM); (ii) the use of bismuth oxide (Bi 2O 3) as an additive to the negative electrode. The EPMs are applied to the separator to provide a barrier to silver penetration without impairing performance. This allows the use of very thin separators and/or a reduction in the number of layers required. This provides an increase in the available volume for active materials with a consequent improvement in volumetric energy density. The effect of the additives to the negative electrode is to inhibit shape change and increase the conductivity of the zinc. The general approach utilized in this program was to incorporate the performance enhancing improvements into a baseline cell design. The baseline has been configured to fit two underwater vehicles currently in use by the US Navy. The development approaches and specific cell configurations are presented along with current performance data. An analysis and critique of the data coupled with conclusions and recommendations for future development activities are also presented.

Skelton, James; Serenyi, Roberto

207

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

PubMed

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

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

2013-08-01

208

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.

209

Electrochemical In-Situ Micropatterning of Cells and Polymers  

Microsoft Academic Search

We report two novel techniques “Electrochemical Bio-Lithography” that enables in-situ cellular micropatterning, and “Ultra\\u000a Anisotropic Electrodeposition” for making micropatterns of conducting polymers. The former technique for cellular micropatterning\\u000a was combined with dielectrophoresis (DEP) and AFM, and we have realized the in-situ spatiotemporal cellular micropatterning\\u000a in various environments. On the other hand, we have found the micropatterned hydrophobic area around electrode

M. Nishizawa; H. Kaji; S. Sekine

210

Development of electrochemical photovoltaic cells. Third technical progress report, November 1, 1979-January 31, 1980  

SciTech Connect

The development of stable, efficient, electrochemical photovoltaic cells based on silicon and gallium arsenide in non-aqueous electrolyte systems is being investigated. The effect of surface condition of silicon electrodes on electrochemical and physical characteristics has been studied. An electrode-supporting electrolyte interaction in acetonitrile has been identified which leads to etching of the surface. Improved performance can result, which has practical significance. Gallium arsenide electrodes have been electrochemically characterized in cells containing propylene carbonate with a ferrocene/ferricenium redox additive. Degradation of the ferricenium salt under illumination has been investigated. Other redox couples studied to date have not given promising results. Long-term stability experiments have been deferred while a better understanding of electrode behavior is being obtained.

Byker, H.J.; Schwerzel, R.E.; Wood, V.E.; Austin, A.E.; Brooman, E.W.

1980-03-07

211

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

Microsoft Academic Search

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

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

2011-01-01

212

Electrochemically deposited cadmium electrode for sealed Ni-Cd cells  

NASA Technical Reports Server (NTRS)

An investigation into the work on electrochemical cadmium deposition processes is describred. A beaker impregnation system is constructed to investigate the practical limits of loading and the effect of various process parameters. Reasonably high loadings of cadmium are obtained and the process appears amenable to tight control and the production of uniform consistent electrodes. A pilot impregnation facility is built to further investigate electrodeposition processes. Both the inert anode and consummable anode processes are investigated. Results of this evaluation and an analysis of associated problems are presented.

Houston, W. H.; Edgar, T. A.

1984-01-01

213

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

Microsoft Academic Search

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

Meng Ni

2011-01-01

214

3D CFD Electrochemical and Heat Transfer Model of an Internally Manifolded Solid Oxide Electrolysis Cell, IMECE 2011.  

National Technical Information Service (NTIS)

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. Thi...

G. G. Tao G. L. Hawkes J. E. O'Brien

2011-01-01

215

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

PubMed

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 10 to 20 mAcm(2). 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 150 mAcm(2), respectively. PMID:17672740

Jiang, Rongzhong

2007-07-01

216

Characterization of microbial fuel cells at microbially and electrochemically meaningful time scales.  

PubMed

The variable biocatalyst density in a microbial fuel cell (MFC) anode biofilm is a unique feature of MFCs relative to other electrochemical systems, yet performance characterizations of MFCs typically involve analyses at electrochemically relevant time scales that are insufficient to account for these variable biocatalyst effects. This study investigated the electrochemical performance and the development of anode biofilm architecture under different external loadings, with duplicate acetate-fed single-chamber MFCs stabilized at each resistance for microbially relevant time scales. Power density curves from these steady-state reactors generally showed comparable profiles despite the fact that anode biofilm architectures and communities varied considerably, showing that steady-state biofilm differences had little influence on electrochemical performance until the steady-state external loading was much larger than the reactor internal resistance. Filamentous bacteria were dominant on the anodes under high external resistances (1000 and 5000 ?), while more diverse rod-shaped cells formed dense biofilms under lower resistances (10, 50, and 265 ?). Anode charge transfer resistance decreased with decreasing fixed external resistances, but was consistently 2 orders of magnitude higher than the resistance at the cathode. Cell counting showed an inverse exponential correlation between cell numbers and external resistances. This direct link of MFC anode biofilm evolution with external resistance and electricity production offers several operational strategies for system optimization. PMID:21329346

Ren, Zhiyong; Yan, Hengjing; Wang, Wei; Mench, Matthew M; Regan, John M

2011-03-15

217

Electrochemical Properties of Carbon Nanotube Fluorides in a Lithium Cell System  

Microsoft Academic Search

Carbon nanotubes synthesized by decomposition of acetylene over silica-supported cobalt catalysts were fluorinated in different conditions : at room or high temperature, ca. 500°C. The electrochemical behaviour of these carbon nanotube fluorides as electrode materials in a lithium cell was investigated using a liquid electrolyte. Results are compared to those obtained with graphite fluoride compounds which present a well known

Andre Hamwi; Philippe Gendraud; Helene Gaucher; Sylvie Bonnamy; Francois Beguin

1998-01-01

218

All Electrochemical Layer Deposition for Crystalline Silicon Solar Cell Manufacturing: Experiments and Interpretation  

Microsoft Academic Search

A manufacturing process for crystalline silicon solar cells is presented which consists mainly of electrochemical steps. The deposition of doping glass layers for the front side emitter as well as the back surface field is performed anodically onto the etched and cleaned wafers. The doping atoms, phosphorus or boron, are diffused into the silicon crystal in a furnace at 950

F. Kröner; Z. Kröner; K. Reichmann; M. Rommel

219

The Effect of Supplementing Instruction with Conceptual Change Texts on Students' Conceptions of Electrochemical Cells  

ERIC Educational Resources Information Center

The aim of this study was to investigate the effectiveness of instruction supplemented by conceptual change texts (CCTs) over traditional instruction on students' understanding of electrochemical (galvanic and electrolytic) cell concepts. The participants of the study consisted of 64 students from the two classes of a high school located in…

Yuruk, Nejla

2007-01-01

220

Conceptual Change Text: A Supplementary Material To Facilitate Conceptual Change in Electrochemical Cell Concepts.  

ERIC Educational Resources Information Center

The main purpose of the study was to investigate the effectiveness of conceptual change text (CCT) oriented instruction over traditionally designed instruction on students' understanding of electrochemical (galvanic and electrolytic) cell concepts. The subjects of the study consisted of 64 students from the two classes of a high school in Turkey.…

Yuruk, Nejla; Geban, Omer

221

Computer Control of Electrochemical Experiments with Application to Zinc/Nickel Oxide Cells.  

National Technical Information Service (NTIS)

A computer-controlled test system has been designed and constructed to allow the simultaneous and continuous cycling of 16 or more electro-chemical cells. The system offers resolution and stability within 0.025% of full-scale, and response times are typic...

E. J. Cairns F. R. McLarnon M. H. Katz

1982-01-01

222

An electrochemical detector array to study cell biology on the nanoscale  

Microsoft Academic Search

Nanobiotechnology is a field that utilizes the techniques of nano- and microfabrication to study biosystems or to use biological material and principles to build new devices. As an example we discuss the development of a nanofabricated electrochemical detector array that reveals the spatio-temporal dynamics of exocytosis in single chromaffin cells. In a quantal release event a single vesicle fuses with

Andrew F. Dias; Gregor Dernick; Vicente Valero; Ming G. Yong; Conrad D. James; Harold G. Craighead; Manfred Lindau

2002-01-01

223

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

224

Characterizing ion profiles in dynamic junction light-emitting electrochemical cells.  

PubMed

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 an in-depth study of the 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 the electrochemical doping processes in LECs. PMID:24175736

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

2013-11-27

225

Copper-substituted perovskite compositions for solid oxide fuel cell cathodes and oxygen reduction electrodes in other electrochemical devices  

DOEpatents

The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells. Also provided are electrochemical devices that include active oxygen reduction electrodes, such as solid oxide fuel cells, sensors, pumps and the like. The compositions comprises a copper-substituted ferrite perovskite material. The invention also provides novel methods for making and using the electrode compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having cathodes comprising the compositions.

Rieke, Peter C. (Pasco, WA) [Pasco, WA; Coffey, Gregory W. (Richland, WA) [Richland, WA; Pederson, Larry R. (Kennewick, WA) [Kennewick, WA; Marina, Olga A. (Richland, WA) [Richland, WA; Hardy, John S. (Richland, WA) [Richland, WA; Singh, Prabhaker (Richland, WA) [Richland, WA; Thomsen, Edwin C. (Richland, WA) [Richland, WA

2010-07-20

226

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

227

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

228

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

229

Electrochemical and electrochemiluminescence determination of cancer cells based on aptamers and magnetic beads.  

PubMed

The electrochemical and electrochemiluminescence (ECL) detection of cell lines of Burkitt's lymphoma (Ramos) by using magnetic beads as the separation tool and high-affinity DNA aptamers for signal recognition is reported. Au nanoparticles (NPs) bifunctionalized with aptamers and CdS NPs were used for electrochemical signal amplification. The anodic stripping voltammetry technology employed for the analysis of cadmium ions dissolved from CdS NPs on the aggregates provided a means to quantify the amount of the target cells. This electrochemical method could respond down to 67 cancer cells per mL with a linear calibration range from 1.0×10(2) to 1.0×10(5) cells mL(-1), which shows very high sensitivity. In addition, the assay was able to differentiate between target and control cells based on the aptamer used in the assay, indicating the wide applicability of the assay for diseased cell detection. ECL detection was also performed by functionalizing the signal DNA, which was complementary to the aptamer of the Ramos cells, with tris(2,2-bipyridyl) ruthenium. The ECL intensity of the signal DNA, replaced by the target cells from the ECL probes, directly reflected the quantity of the amount of the cells. With the use of the developed ECL probe, a limit of detection as low as 89 Ramos cells per mL could be achieved. The proposed methods based on electrochemical and ECL should have wide applications in the diagnosis of cancers due to their high sensitivity, simplicity, and low cost. PMID:20658505

Ding, Caifeng; Ge, Ying; Zhang, Shusheng

2010-09-17

230

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

231

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

DOEpatents

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

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

1992-01-01

232

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

233

Cellulose synthesis in two secondary cell wall processes in a single cell type  

PubMed Central

Plant cells have a rigid cell wall that constrains internal turgor pressure yet extends in a regulated and organized manner to allow the cell to acquire shape. The primary load-bearing macromolecule of a plant cell wall is cellulose, which forms crystalline microfibrils that are organized with respect to a cell's function and shape requirements. A primary cell wall is deposited during expansion whereas secondary cell wall is synthesized post expansion during differentiation. A complex form of asymmetrical cellular differentiation occurs in Arabidopsis seed coat epidermal cells, where we have recently shown that two secondary cell wall processes occur that utilize different cellulose synthase (CESA) proteins. One process is to produce pectinaceous mucilage that expands upon hydration and the other is a radial wall thickening that reinforced the epidermal cell structure. Our data illustrate polarized specialization of CESA5 in facilitating mucilage attachment to the parent seed and CESA2, CESA5 and CESA9 in radial cell wall thickening and formation of the columella. Herein, we present a model for the complexity of cellulose biosynthesis in this highly differentiated cell type with further evidence supporting each cellulosic secondary cell wall process.

Mendu, Venugopal; Stork, Jozsef; Harris, Darby; DeBolt, Seth

2011-01-01

234

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

235

Electroendocytosis Is Driven by the Binding of Electrochemically Produced Protons to the Cell's Surface  

PubMed Central

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

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

2012-01-01

236

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

237

Process for making an electrochemical cell or battery, e. g. a fuel cell or fuel cell battery, and a cell or battery made by the process  

Microsoft Academic Search

An electrochemical cell or battery in a monolithic form is produced, in which a series of planar sheet electrodes are disposed in a framework of a fibrous material which contains a thermosetting resin. The process for forming the cell or battery is also disclosed.

M. Alfenaar; R. L. E. Van Gasse

1977-01-01

238

One-step electrochemically-codeposited polyaniline-platinum for dye-sensitized solar cell applications  

NASA Astrophysics Data System (ADS)

Platinum, polyaniline and composite polyaniline-platinum films were coated on conductive glass by using electrochemical deposition. They were then used as dye-sensitized solar cell counter electrodes. The efficiencies of platinum, polyaniline and composite polyaniline-platinum cells were 2.47, 4.47 and 6.62%, respectively. The improvement of composite polyaniline-platinum solar cell efficiency over pure polyaniline and platinum cells is because of an increase in the filmu2019s catalytic activity and a decrease in charge-transfer resistance between its counter electrode and electrolyte, as observed by using cyclic voltammogram and electrochemical impedance spectroscopy measurements, respectively. Co-deposition of polyaniline and Pt catalysts was confirmed by the presence of Pt and N peaks in the X-ray photoelectron spectroscopy spectrum.

Thiangkaew, Anongnad; Keothongkham, Khamsone; Maiaugree, Wasan; Jarernboon, Wirat; Kamwanna, Teerasak; Pimanpang, Samuk; Amornkitbamrung, Vittaya

2014-05-01

239

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

240

Suppressing spatiotemporal disorder via local perturbations in an electrochemical cell.  

PubMed

We report experimental results depicting suppression of complex spatiotemporal dynamics under the influence of local periodic stimulations. In an experimental electrochemical system, applying a continuous forcing signal to one of the sites in an array of eight coupled oscillators, the naturally complex behavior of the remaining seven electrodes can be converted to periodic responses. The oscillations remain periodic as long as the forcing is active and revert back to exhibiting chaotic dynamics after the control is switched off. These results can also be interpreted as experimental realization of "phase-synchronization" induced via local driving in an extended system. A possible relevance to the experimentally observed calcium wave patterns is pointed out. PMID:11909145

Parmananda, P; Green, B J; Hudson, J L

2002-03-01

241

Three-dimensional analysis of transport and electrochemical reactions in polymer electrolyte fuel cells  

Microsoft Academic Search

A computational fuel cell dynamics (CFCD) model is presented to elucidate three-dimensional (3D) interactions between mass transport and electrochemical kinetics in polymer electrolyte fuel cells with straight and interdigitated flowfields, respectively. The model features a detailed membrane–electrode assembly (MEA) submodel in which water transport through the membrane with spatially variable transport properties and spatial variations of the reaction rate and

Sukkee Um; C. Y. Wang

2004-01-01

242

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

243

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

Microsoft Academic Search

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

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

2012-01-01

244

Analysis of electrochemical impedance spectroscopy in proton exchange membrane fuel cells  

Microsoft Academic Search

SUMMARY A literature review of electrochemical impedance spectroscopy (EIS) analysis of proton exchange membrane fuel cells (PEMFCs) is presented. Emphasis is placed on the papers that analyse the impedance response of the cathode and anode half-cells of the PEMFCs based on a continuum-mechanics approach. The other type of analysis, which is based on the equivalent-circuits approach, is addressed for comparison.

Parthasarathy M. Gomadam; John W. Weidnern

2005-01-01

245

Elastomeric binders for electrodes. [in secondary lithium cells  

NASA Technical Reports Server (NTRS)

The poor mechanical integrity of the cathode represents an important problem which affects the performance of ambient temperature secondary lithium cells. Repeated charge of a TiS2 cathode may give rise to stresses which disturb the electrode structure and can contribute to capacity loss. An investigation indicates that the use of an inelastic binder material, such as Teflon, aggravates the problem, and can lead to electrode disruption and poor TiS2 particle-particle contact. The feasibility of a use of elastomers as TiS2 binder materials has, therefore, been explored. It was found that elastomeric binders provide an effective approach for simplifying rechargeable cathode fabrication. A pronounced improvement in the mechanical integrity of the cathode structure contributes to a prolonged cycle life.

Yen, S. P. S.; Shen, D. H.; Somoano, R. B.

1983-01-01

246

Electrochemical impedance spectroscopy analysis of a thin polymer film-based micro-direct methanol fuel cell  

Microsoft Academic Search

A single cell micro-direct methanol fuel cell (micro-DMFC) was investigated using electrochemical impedance spectroscopy. The electrodes consisted of thin, flexible polymer (SU8) film microchannel structures fabricated in-house using microfabrication techniques. AC impedance spectroscopy was used to separate contributions to the overall cell polarization from the anode, cathode and membrane. A clear distinction between the different electrochemical phenomena occurring in the

Tobias Schulz; Christian Weinmüller; Majid Nabavi; Dimos Poulikakos

2010-01-01

247

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.

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

2013-01-01

248

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

PubMed Central

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

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

2013-01-01

249

Harvesting waste thermal energy using a carbon-nanotube-based thermo-electrochemical cell.  

PubMed

Low efficiencies and costly electrode materials have limited harvesting of thermal energy as electrical energy using thermo-electrochemical cells (or "thermocells"). We demonstrate thermocells, in practical configurations (from coin cells to cells that can be wrapped around exhaust pipes), that harvest low-grade thermal energy using relatively inexpensive carbon multiwalled nanotube (MWNT) electrodes. These electrodes provide high electrochemically accessible surface areas and fast redox-mediated electron transfer, which significantly enhances thermocell current generation capacity and overall efficiency. Thermocell efficiency is further improved by directly synthesizing MWNTs as vertical forests that reduce electrical and thermal resistance at electrode/substrate junctions. The efficiency of thermocells with MWNT electrodes is shown to be as high as 1.4% of Carnot efficiency, which is 3-fold higher than for previously demonstrated thermocells. With the cost of MWNTs decreasing, MWNT-based thermocells may become commercially viable for harvesting low-grade thermal energy. PMID:20170193

Hu, Renchong; Cola, Baratunde A; Haram, Nanda; Barisci, Joseph N; Lee, Sergey; Stoughton, Stephanie; Wallace, Gordon; Too, Chee; Thomas, Michael; Gestos, Adrian; Cruz, Marilou E Dela; Ferraris, John P; Zakhidov, Anvar A; Baughman, Ray H

2010-03-10

250

Electrochemical communication between microbial cells and electrodes via osmium redox systems.  

PubMed

Electrochemical communication between micro-organisms and electrodes is the integral and fundamental part of BESs (bioelectrochemical systems). The immobilization of bacterial cells on the electrode and ensuring efficient electron transfer to the electrode via a mediator are decisive features of mediated electrochemical biosensors. Notably, mediator-based systems are essential to extract electrons from the non-exoelectrogens, a major group of microbes in Nature. The advantage of using polymeric mediators over diffusible mediators led to the design of osmium redox polymers. Their successful use in enzyme-based biosensors and BFCs (biofuel cells) paved the way for exploring their use in microbial BESs. The present mini-review focuses on osmium-bound redox systems used to date in microbial BESs and their role in shuttling electrons from viable microbial cells to electrodes. PMID:23176477

Hasan, Kamrul; Patil, Sunil A; Leech, Dónal; Hägerhäll, Cecilia; Gorton, Lo

2012-12-01

251

Anodes - Materials for negative electrodes in electrochemical energy technology  

NASA Astrophysics Data System (ADS)

The basic concepts of electrodes and electrochemical cells (including both galvanic and electrolytic ones) are introduced and illustrated with practical examples. Particular attention is paid to negative electrodes in primary and secondary cells, fuel cell electrodes and electrodes in redox flow batteries. General features and arguments pertaining to selection, optimization and further development are highlighted.

Holze, Rudolf

2014-06-01

252

Interfacial phenomena observed in electrochemical systems (lithium-ion batteries, fuel cells, dye sensitized solar cells); causes, relevance and enhancements  

NASA Astrophysics Data System (ADS)

This dissertation is aimed to understand the interfacial phenomena in electrochemical systems. Three electrochemical systems, namely, Lithium Ion Batteries, Fuel Cells and Dye Sensitized Solar Cells were chosen to elucidate the different type of the interfaces involved. In Lithium ion batteries the interface between an electrode and an electrolyte called as the solid electrolyte interface plays an important role in the electrochemical performance. Solid electrolyte interface also has a direct correlation with thermal runaway which causes such systems to explode. An in-depth analysis of this interface has been explored using techniques such as differential scanning calorimeter (DSC), accelerating rate calorimeter (ARC) as well as material characterization by X-ray diffraction (XRD) and Transmission Electron Microscope (TEM). Electrochemical Impedance spectroscopy has also been used extensively in conjunction with the techniques mentioned above. In Fuel Cells, novel spiral flow channels have been proposed. The objective of these flow channels is to increase the effective reactant distribution to the surface of the catalyst and effectively remove water being formed as the reactant products at the catalyst interface. With respect to fuel cells, most of the work is towards catering to the interface rather that dealing directly with the interfacial phenomena (catalyst, membranes). In-situ neutron scattering were conducted to visualize the water formation and draining mechanism in the proposed spiral flow channels. In Dye Sensitized solar cells, the interface plays an important role in terms of the performance over a long period of time. Preliminary investigation has been carried out using electrochemical impedance spectroscopy (EIS) and the different regions within an operating cell have been identified.

Amiruddin, Shabab

253

Two-signal electrochemical method for evaluation suppression and proliferation of MCF-7 cells based on intracellular purine.  

PubMed

Two electrochemical signals ascribed to xanthine/guanine and hypanthine/adenine in MCF-7 cells were detected at 0.726 and 1.053V, respectively. Based on the intensity of signals, the genistein-induced proliferation and suppression of MCF-7 cells could be evaluated. The results showed that with the increase of genistein dose at the range of 10(-9) to 10(-6)M, the two electrochemical signals of MCF-7 cell suspension increased due to the proliferation, whereas the tendency at the high dosage range of more than 10(-5)M was decreased. The proliferation and cytotoxicity obtained by the electrochemical method were in agreement with those obtained by cell counting and the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium] method. Thus, the two-signal electrochemical method is an effective way to evaluate the effect of drugs on cell activity based on purine metabolism. PMID:24680752

Li, Jinlian; Lin, Runxian; Wang, Qian; Gao, Guanggang; Cui, Jiwen; Liu, Jiguang; Wu, Dongmei

2014-07-01

254

Design and Operation of an Electrochemical Methanol Concentration Sensor for Direct Methanol Fuel Cell Systems  

NASA Technical Reports Server (NTRS)

The development of a 150-Watt packaged power source based on liquid feed direct methanol fuel cells is being pursued currently at the Jet propulsion Laboratory for defense applications. In our studies we find that the concentration of methanol in the fuel circulation loop affects the electrical performance and efficiency the direct methanol fuel cell systems significantly. The practical operation of direct methanol fuel cell systems, therefore, requires accurate monitoring and control of methanol concentration. The present paper reports on the principle and demonstration of an in-house developed electrochemical sensor suitable for direct methanol fuel cell systems.

Narayanan, S. R.; Valdez, T. I.; Chun, W.

2000-01-01

255

Development of a bipolar cell for electrochemical production of lithium  

Microsoft Academic Search

Lithium metal can be electrolytically refined from aqueous solutions of its compounds by partial reduction to form a lithium amalgam, followed by reduction of the amalgam to liquid lithium in a molten salt cell at 225 C. A bipolar cell (with a continuous, amalgam electrode circulating between the aqueous and salt cells) was designed, constructed and successfully tested on the

J. F. Cooper; G. Mack; K. Peterman; S. Weinland; P. McKenzie

1995-01-01

256

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

DOEpatents

An electrochemical apparatus is made having a generator section containing axially elongated electrochemical cells, a fresh gaseous feed fuel inlet, a gaseous feed oxidant inlet, and at least one gaseous spent fuel exit channel, where the spent fuel exit channel passes from the generator chamber to combine with the fresh feed fuel inlet at a mixing apparatus, reformable fuel mixture channel passes through the length of the generator chamber and connects with the mixing apparatus, that channel containing entry ports within the generator chamber, where the axis of the ports is transverse to the fuel electrode surfaces, where a catalytic reforming material is distributed near the reformable fuel mixture entry ports. 2 figures.

Reichner, P.; Dollard, W.J.

1991-01-08

257

Further observations on the phenomenon of secondary vacuolation in living cells.  

NASA Technical Reports Server (NTRS)

The dynamics of secondary vacuole movement is studied in living hair cells of Tradescantia virginiana. The pattern of movement of these vacuoles is found to be similar to that described by the author previously for organelles in cultured cells. Evidence is presented in support of the thesis that the occurrence and dynamics of secondary vacuoles is a common phenomenon for plant cells.

Mahlberg, P.

1972-01-01

258

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.

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

2011-01-01

259

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

260

Transfected single-cell imaging by scanning electrochemical optical microscopy with shear force feedback regulation.  

PubMed

Gene-transfected single HeLa cells were characterized using a scanning electrochemical/optical microscope (SECM/OM) system with shear-force-based probe-sample distance regulation to simultaneously capture electrochemical, fluorescent, and topographic images. The outer and inner states of single living cells were obtained as electrochemical and fluorescent signals, respectively, by using an optical fiber-nanoelectrode probe. A focused ion beam (FIB) was used to mill the optical aperture and the ring electrode at the probe apex (the inner and outer radii of the ring electrode were 37 and 112 nm, respectively). To apply an appropriate shear force between the probe tip and the living cell surface, we optimized the amplitude of oscillation of the tuning fork to which the probe was attached. Field-programmable gate arrays (FPGA) were adopted to drastically increase the feedback speed of the tip-sample distance regulation, shorten the scanning time for imaging, and enhance the accuracy and quality of the living cell images. In employing these improvements, we simultaneously measured the cellular expression activity of both secreted alkaline phosphatase outside and GFP inside by using the SECM/OM with shear force distance regulation. PMID:19883061

Takahashi, Yasufumi; Shiku, Hitoshi; Murata, Tatsuya; Yasukawa, Tomoyuki; Matsue, Tomokazu

2009-12-01

261

Development of a bipolar cell for electrochemical production of lithium  

SciTech Connect

Lithium metal can be electrolytically refined from aqueous solutions of its compounds by partial reduction to form a lithium amalgam, followed by reduction of the amalgam to liquid lithium in a molten salt cell at 225 C. A bipolar cell (with a continuous, amalgam electrode circulating between the aqueous and salt cells) was designed, constructed and successfully tested on the bench scale, as a proof of principle of an efficient, safe and low-temperature alternative to existing processes.

Cooper, J.F.; Mack, G.; Peterman, K.; Weinland, S. [Lawrence Livermore National Lab., CA (United States); McKenzie, P. [Martin Marietta Energy Systems, Inc., Oak Ridge, TN (United States)

1995-02-22

262

Electrochemical impedance spectroscopy of lithium-titanium disulfide rechargeable cells  

Microsoft Academic Search

The two-terminal alternating current impedance of Li\\/TiS2 rechargeable cells was studied as a function of frequency, state-of-charge, and extended cycling. Analysis based on a plausible equivalent circuit model for the Li\\/TiS2 cell leads to evaluation of kinetic parameters for the various physicochemical processes occurring at the electrode\\/electrolyte interfaces. To investigate the causes of cell degradation during extended cycling, the parameters

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

1993-01-01

263

Electrochemical impedance spectroscopy of lithium-titanium disulfide rechargeable cells  

Microsoft Academic Search

The two-terminal alternating current impedance of lithium-titanium disulfide (Li\\/TiS[sub 2]) rechargeable cells has been studies as a function of frequency, state-of-charge, and extended cycling. Analysis based on a plausible equivalent circuit model for the Li\\/TiS[sub 2] cell leads to evaluation of kinetic parameters for the various physicochemical processes occurring at the electrode\\/electrolyte interfaces. To investigate the causes of cell degradation

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

1993-01-01

264

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.

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

2011-01-01

265

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

266

Enhanced electricity generation for microbial fuel cell by using electrochemical oxidation to modify carbon cloth anode  

NASA Astrophysics Data System (ADS)

Different types of treatment methods for anode materials are reported to enhance power production in microbial fuel cells (MFCs). Here we report a simple, cost-effective and environmentally friendly electrochemical oxidation technique that is used to modify the carbon cloth for the improvement of MFC performance. Carbon cloth is immersed in a 5% NH4HCO3 solution and then the solution is oxidized at different set currents. Optimal performance is obtained at 14 mA cm-2 with an oxidation time of 2 min, based on production of a maximum power density of 939 ± 7 mW m-2 in MFC tests, which is 14.2% higher than that of the untreated carbon cloth control. This treatment method increases the electrochemical active surface area by 2.9 times (from 11.2 to 44.1 cm2), and improves the exchange current density by 41% (from 4.79 × 10-4 to 6.76 × 10-4 A m-2). XPS analysis indicates that electrochemical oxidation in this solution introduced amide groups onto the electrode surface, which likely improves bacterial adsorption and current production. These results show that simple electrochemical treatment method can increase active surface area and alter carbon cloth anodes in ways that increase power production of the MFC.

Liu, Jia; Liu, Junfeng; He, Weihua; Qu, Youpeng; Ren, Nanqi; Feng, Yujie

2014-11-01

267

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

268

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

269

Cell-Adhesive and Cell-Repulsive Zwitterionic Oligopeptides for Micropatterning and Rapid Electrochemical Detachment of Cells  

PubMed Central

In this study, we describe the development of oligopeptide-modified cell culture surfaces from which adherent cells can be rapidly detached by application of an electrical stimulus. An oligopeptide, CGGGKEKEKEK, was designed with a terminal cysteine residue to mediate binding to a gold surface via a gold–thiolate bond. The peptide forms a self-assembled monolayer through the electrostatic force between the sequence of alternating charged glutamic acid (E) and lysine (K) residues. The dense and electrically neutral oligopeptide zwitterionic layer of the modified surface was resistant to nonspecific adsorption of proteins and adhesion of cells, while the surface was altered to cell adhesive by the addition of a second oligopeptide (CGGGKEKEKEKGRGDSP) containing the RGD cell adhesion motif. Application of a negative electrical potential to this gold surface cleaved the gold–thiolate bond, leading to desorption of the oligopeptide layer, and rapid (within 2?min) detachment of virtually all cells. This approach was applicable not only to detachment of cell sheets but also for transfer of cell micropatterns to a hydrogel. This electrochemical approach of cell detachment may be a useful tool for tissue-engineering applications.

Kakegawa, Takahiro; Mochizuki, Naoto; Sadr, Nasser; Suzuki, Hiroaki

2013-01-01

270

Development and electrochemical studies of gas diffusion electrodes for polymer electrolyte fuel cells  

Microsoft Academic Search

Electrochemical studies on low catalyst loading gas diffusion electrodes for polymer electrolyte fuel cells are reported. The best performance is obtained with an electrode formed from 20 wt% Pt\\/C, 0.4 mg Pt cm-2 and 1.1 mg Nafion® cm-2 in the catalyst layer and 15% PTFE in a diffusion layer of 50 µm thickness, for both the cathode and the anode.

V. A. Paganin; E. A. Ticianelli; E. R. Gonzalez

1996-01-01

271

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

Microsoft Academic Search

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

R. Noufi; D. Tench; L. Warren

1980-01-01

272

High Selective deNO x Electrochemical Cell with Self-Assembled Electro-Catalytic Electrode  

Microsoft Academic Search

A new family of electrochemical cells for decomposition of NO gas in the presence of excess O2, in which the cathode was covered with mixed oxide layer of NiO and YSZ (electro-catalytic electrode) were designed and investigated. The deNOx properties were increased by microstructural and compositional control of the electro-catalytic electrode. Nano-size Ni grains were self-assembled at NiO\\/YSZ interfaces by

Takuya Hiramatsu; Sergei I. Bredikhin; Shingo Katayama; Osamu Shiono; Koichi Hamamoto; Yoshinobu Fujishiro; Masanobu Awano

2004-01-01

273

The Effect of Supplementing Instruction with Conceptual Change Texts on Students’ Conceptions of Electrochemical Cells  

Microsoft Academic Search

The aim of this study was to investigate the effectiveness of instruction supplemented by conceptual change texts (CCTs) over\\u000a traditional instruction on students’ understanding of electrochemical (galvanic and electrolytic) cell concepts. The participants\\u000a of the study consisted of 64 students from the two classes of a high school located in Turkey. Classes were randomly assigned\\u000a to experimental group, which was

Nejla Yürük

2007-01-01

274

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

275

Electrochemically deposited zinc oxide for light trapping in thin film silicon solar cell  

Microsoft Academic Search

Electrochemically deposited ZnO films which have the appropriate texture surface for light trapping effect in solar cells are presented. A voltage was applied between anodes and Ag-coated-stainless steel substrate as a cathode in the heated aqueous solution of Zn(NO\\/sub 3\\/)\\/sub 2\\/ and ZnO films were formed on the substrate. The specular-and-diffuse and diffuse reflectance at 800nm wavelength were 94.3% and

N. Toyama; R. Hayashi; Y. Sonoda; M. Iwata; Y. Miyamoto; H. Otoshi; K. Saito; K. Ogawa

2003-01-01

276

Electronic circuit for measuring series connected electrochemical cell voltages  

DOEpatents

An electronic circuit for measuring voltage signals in an energy storage device is disclosed. The electronic circuit includes a plurality of energy storage cells forming the energy storage device. A voltage divider circuit is connected to at least one of the energy storage cells. A current regulating circuit is provided for regulating the current through the voltage divider circuit. A voltage measurement node is associated with the voltage divider circuit for producing a voltage signal which is proportional to the voltage across the energy storage cell.

Ashtiani, Cyrus N. (West Bloomfield, MI); Stuart, Thomas A. (Toledo, OH)

2000-01-01

277

Microfluidic electrochemical reactors  

DOEpatents

A microfluidic electrochemical reactor includes an electrode and one or more microfluidic channels on the electrode, where the microfluidic channels are covered with a membrane containing a gas permeable polymer. The distance between the electrode and the membrane is less than 500 micrometers. The microfluidic electrochemical reactor can provide for increased reaction rates in electrochemical reactions using a gaseous reactant, as compared to conventional electrochemical cells. Microfluidic electrochemical reactors can be incorporated into devices for applications such as fuel cells, electrochemical analysis, microfluidic actuation, pH gradient formation.

Nuzzo, Ralph G. (Champaign, IL); Mitrovski, Svetlana M. (Urbana, IL)

2011-03-22

278

Novel duplex vapor-electrochemical method for silicon solar cells  

NASA Astrophysics Data System (ADS)

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.

1980-03-01

279

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

280

Electrochemical impedance spectroscopy of lithium-titanium disulfide rechargeable cells  

NASA Astrophysics Data System (ADS)

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

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

1993-07-01

281

Electrochemical impedance spectroscopy of lithium-titanium disulfide rechargeable cells  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

282

Electrochemical High Pressure Pump.  

National Technical Information Service (NTIS)

The invention provides electrochemically-based methods and devices for producing fluid flow and/or changes in fluid pressure. In the methods and devices of the invention, current is passed through a divided electrochemical cell. Adjacent compartments of t...

C. A. Koval C. E. Evans M. A. Norman R. D. Noble

2005-01-01

283

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

284

Electrochemical and surface science research on fuel cells  

NASA Astrophysics Data System (ADS)

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

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

1984-06-01

285

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.

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

2013-01-01

286

Electrochemical behavior of CIGS electrodeposition for applications to photovoltaic cells  

NASA Astrophysics Data System (ADS)

The electrodeposition mechanism of Cu(In,Ga)Se2 (CIGS) thin films on ITO substrates was examined by using cyclic voltammetry (CV). The CV study was performed in unitary In, binary In-Se, ternary Cu-In-Se, and quaternary Cu-In-Ga-Se systems. CV of the Cu-In-Ga-Se system revealed a reduction peak at -0.6 V with the addition of GaCl3 and showed that the current density was affected significantly by the concentrations of GaCl3 and InCl3. This is probably due to the adsorption-site competition between In3+ and Ga3+ on the electrode surface. Energy dispersive X-ray spectroscopy confirmed the CV results. The composition of Ga in the CIGS films increased with increasing concentration of GaCl3 in the electrolyte whereas the composition of In decreased sharply. The as-deposited films were annealed at 500 °C in a N2 atmosphere for crystallization. XRD revealed three major peaks corresponding to the (112), (220) and (312) planes of CIGS chalcopyrite respectively. On the other hand, a secondary phase, such as In4Se3, was observed in the CIGS films containing a high In composition.

Lee, Hyunju; Ji, Changwook; Kim, Yangdo; Lee, Jae-Ho; Hwang, Yoon-Hwae; Jo, Ilguk; Kim, Hyoungchan

2014-04-01

287

The responses of primary and secondary sensory hair cells in the squid statocyst to mechanical stimulation  

Microsoft Academic Search

Intracellular recordings were obtained from primary and secondary sensory hair cells in the anterior transverse crista segment of the squid (Alloteuthis subulata) statocyst during imposed displacements of the overlying cupula. The secondary sensory hair cells were depolarized by ventral movements of the cupula and hyperpolarized by dorsal cupula movements. The displacement\\/response curve was asymmetric around the zero position and sigmoidal

R. Williamson

1990-01-01

288

Teaching cell division to secondary school students: an investigation of difficulties experienced by Turkish teachers  

Microsoft Academic Search

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 one of the most difficult subjects. Meiosis

Haydar Öztap; Esra Özay; Fulya Öztap

2003-01-01

289

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

290

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

291

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

292

Fabrication of VB2/air cells for electrochemical testing.  

PubMed

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for synthesizing nanoscopic VB2 is presented as well as step-by-step procedure for applying a zirconium oxide coating to the VB2 particles for stabilization upon discharge. The process for disassembling existing zinc/air cells is shown, in addition construction of the new working electrode to replace the conventional zinc/air cell anode with a the nanoscopic VB2 anode. Finally, discharge of the completed VB2/air battery is reported. We show that using the zinc/air cell as a test bed is useful to provide a consistent configuration to study the performance of the high-energy high capacity nanoscopic VB2 anode. PMID:23962835

Stuart, Jessica; Lopez, Ruben; Lau, Jason; Li, Xuguang; Waje, Mahesh; Mullings, Matthew; Rhodes, Christopher; Licht, Stuart

2013-01-01

293

Evaluation of ceramic insulators for lithium electrochemical reduction cells  

SciTech Connect

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

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

1992-08-01

294

Electrochemical Filtering of CO from Fuel-Cell Reformate  

Microsoft Academic Search

Proton exchange membrane fuel cells ~PEMFC! operating on pure hydrogen show good polarization characteristics over a wide range of load and temperature conditions. However, using pure H2 as a fuel in automotive and residential applications has many limi- tations. The infrastructure to deliver H 2 is inadequate, the refueling of gaseous H2 can be slow, and the storage of H2

Balasubramanian Lakshmanan; Wayne Huang; John W. Weidner

2002-01-01

295

Improved conversion rates in drug screening applications using miniaturized electrochemical cells with frit channels.  

PubMed

This paper reports a novel design of a miniaturized three-electrode electrochemical cell, the purpose of which is aimed at generating drug metabolites with a high conversion efficiency. The working electrode and the counter electrode are placed in two separate channels to isolate the reaction products generated at both electrodes. The novel design includes connecting channels between these two electrode channels to provide a uniform distribution of the current density over the entire working electrode. In addition, the effect of ohmic drop is decreased. Moreover, two flow resistors are included to ensure an equal flow of analyte through both electrode channels. Total conversion of fast reacting ions is achieved at flow rates up to at least 8 ?L/min, while the internal chip volume is only 175 nL. Using this electrochemical chip, the metabolism of mitoxantrone is studied by microchip electrospray ionization-mass spectrometry. At an oxidation potential of 700 mV, all known metabolites from direct oxidation are observed. The electrochemical chip performs equally well, compared to a commercially available cell, but at a 30-fold lower flow of reagents. PMID:23020795

Odijk, Mathieu; Olthuis, Wouter; van den Berg, A; Qiao, Liang; Girault, Hubert

2012-11-01

296

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 1.5µM. 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

297

Fabrication of carbon nanotubes/RGD peptide composites to enhance electrochemical performance of cell chip.  

PubMed

A cell chip is a valuable tool to evaluate the effects of anticancer drugs, antibiotics and environmental toxicants on various kinds of cells. In this study, a conductive composite material composed of multi-walled carbon nanotubes (CNTs) and RGD-MAP-C peptide was fabricated on gold electrode surface for enhancing electrochemical signals from HEK293T cells. The topological characteristics and electrochemical performance of composite materials with different concentrations of CNTs were analyzed by scanning electron microscopy and cyclic voltammetry (CV), respectively. CNTs/RGD peptide composites (CP) electrode containing 20 microg/ml CNT was found to be excellent for improving the sensitivity of cell chip compared with that of bare gold or RGD peptide modified electrode. Finally, two kinds of nephrotoxic antibiotics were treated to HEK293T cells and their toxicity were successfully monitored by CV. Our CP composites can be used as a suitable conducting material for the fabrication of various kinds of cell-based chips. PMID:23926807

Cho, Hyeon-Yeol; Eun-Bi-Ko; Kim, Tae-Hyung; Choi, Jeong-Woo

2013-08-01

298

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

299

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

300

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

301

Monitoring the development of a microbial electrolysis cell bioanode using an electrochemical quartz crystal microbalance.  

PubMed

In this paper we explored the use of an electrochemical quartz crystal microbalance (QCM) to follow the development of electrochemically active biofilms on electrodes. With this technique it should be possible to monitor simultaneously the increase in biomass and the current generated by the electrogenic bacteria in the biofilm. We monitored the adsorption and the subsequent growth of bacteria that are used in microbial electrolysis cells, on a gold electrode (anode). After attachment it took about 3h for the bacteria to start to grow and develop a biofilm. Although the current was still relatively low, there is a clear correlation with the increase in biomass. The method is promising for the further investigation of the development of biofilms on electrodes (bioelectrodes). PMID:20494628

Kleijn, J Mieke; Lhuillier, Quentin; Jeremiasse, Adriaan W

2010-10-01

302

An efficient nanomaterial-based electrochemical biosensor for sensitive recognition of drug-resistant leukemia cells.  

PubMed

A novel electrochemical cytosensor was developed for the fast and high-sensitivity recognition of drug-resistant leukemia K562/ADM cells based on the P-glycoprotein (P-gp) expression level on a cell membrane. The nanocomposite interface of the gold nanoparticles/polyaniline nanofibers (AuNPs/PANI-NF) was chosen to design the biosensor for electrochemical detection. Au/PANI-NF-based cytosensors coated with anti-P-glycoprotein (anti-P-gp) molecules could provide a biomimetic interface for the immunosensing of cell surface P-glycoprotein, and thus could capture the over-expression P-gp cells. Transmission electron microscopy (TEM) indicated that the gold nanoparticles were uniformly anchored along the structure of the PANI-NF surface, displaying fibrillar morphology with a diameter of ?70 nm, and atomic force microscopy (AFM) further presented the morphology of the nanocomposite film. Owing to the high affinity of anti-P-gp for leukemia K562/ADM cells of the propounded sensing platform, the proposed biosensor exhibited excellent analytical performance for leukemia K562/ADM cells, ranging from 1.6 × 10(2) to 1.6 × 10(6) cells per mL with a detection limit of 80 cells per mL. Recovery experiments indicated that the sensitivity reported here is suitable for practical application. The cell surface P-gp expression level was analysed by flow cytometric experiments, which confirmed the above recognized result. This strategy is also a cost-effective and convenient operation, implying great promise for the sensitive recognition of cancer cells and cell surface receptors; thus, it is helpful in cancer diagnosis. PMID:24889704

Zhang, Shaolian; Zhang, Lu; Zhang, Xi; Yang, Peihui; Cai, Jiye

2014-06-16

303

Electrochemical and flow characterization of a direct methanol fuel cell  

NASA Astrophysics Data System (ADS)

Two-phase phenomena, i.e. bubble flow in the anode and water flooding in the cathode, are critical to design of high-performance direct methanol fuel cells (DMFC). A 5 cm 2 transparent DMFC has been developed to visualize these phenomena in situ. Two types of membrane-electrode assembly (MEA) based on Nafion ® 112 were used to investigate effects of backing pore structure and wettability on cell polarization characteristics and two-phase flow dynamics. One employed carbon paper backing material and the other carbon cloth. Experiments were performed under conditions of various methanol feed concentrations. The transparent fuel cell was shown to reach a peak power of 93 mW/cm 2 at 0.3 V, using Toray carbon-paper based MEA under 2 M methanol solution preheated at 85 °C. For the hydrophobic carbon paper backing, it was observed that CO 2 bubbles nucleate at certain locations and form large and discrete bubble slugs in the channel. For the hydrophilic carbon cloth backing, it was shown that bubbles are produced more uniformly and of smaller size. It is thus shown that the anode backing layer of uniform pore size and more hydrophilicity is preferred for gas management in the anode. Flow visualization of water flooding on the cathode side of DMFC has also been carried out. It is shown that liquid droplets appear more easily on the surface of carbon paper due to its reduced hydrophobicity at elevated temperature. For the single-side ELAT carbon cloth, liquid droplets tend to form in the corner between the current collecting rib and GDL since ELAT is highly hydrophobic and the rib (stainless steel) surface is hydrophilic.

Lu, G. Q.; Wang, C. Y.

304

Navigating the transcriptional roadmap regulating plant secondary cell wall deposition  

PubMed Central

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

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

2013-01-01

305

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  

Microsoft Academic Search

SbPO4, a phosphate with a layered structure, was tested as an electrode material for lithium cells spanning the 3.0–0.0V range. Two main electrochemical processes were detected as extensive plateaus at ca. 1.6 and 0.7V 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

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

2004-01-01

306

Reaction of SbPO4 with lithium in non-aqueous electrochemical cells: preliminary study and evaluation of its electrochemical performance in anodes for lithium ion batteries  

Microsoft Academic Search

SbPO4, 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

J. Santos Pena; J. Cuart Pascual; A. Caballero; J. Morales; L. Sanchezb

307

Electrical and Electrochemical Performance Characteristics of Small Commercial Li-Ion Cells  

SciTech Connect

Advanced rechargeable lithium-ion batteries are presently being developed and commercialized worldwide for use in consumer electronics, military and space applications. At Sandia National Laboratories we have used different electrochemical techniques such as impedance and charge/discharge at ambient and subambient temperatures to probe the various electrochemical processes that are occurring in Li-ion cell. The purpose of this study is to identify the component that reduces the cell performance at subambient temperatures. Our impedance data suggest that while the variation in the electrolyte resistance between room temperature and {minus}20 C is negligible the anode electrolyte interfacial resistance increases by an order of magnitude in the same temperature regime. We believe that the solid electrolyte interface (SEI) layer on the carbon anode may be responsible for the increase in cell impedance. We have also evaluated the cells in hybrid mode with capacitors. High-current operation in the hybrid mode allowed fill usage of the Li-ion cell capacity at 25 C and showed a factor of 5 improvement in delivered capacity at {minus}20 C.

Ingersoll, D.; Nagasubramanian, G.; Roth, E.P.

1998-12-22

308

Relationships among electrochemical, thermodynamic, and oxygen potential quantities in lithium-transition metal-oxygen molten salt cells  

Microsoft Academic Search

The interdependence of thermodynamic parameters, phase equilibria, and electrochemical measurements can be used as a powerful tool in the development of high specific energy cells. These principles were used in the analysis of electrochemical experiments performed on ternary lithium-transition metal-oxide (M = Mn, Fe, and Co) positive electrodes. The free energies of formation of LiMnOâ, LiâFeOâ, LiFeOâ, and LiCoOâ were

N. A. Godshall; R. A. Huggins; I. D. Raistrick

1984-01-01

309

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

310

Electrochemical oxidation of cyanide in the hydrocyclone cell  

SciTech Connect

A diluted electroplating cyanide rinse water has been used to test the use of the hydrocyclone cell (HCC) in batch recycle mode of operation for the simultaneous oxidation of cyanide during the electrodeposition of silver. The results obtained in this work with regard to the final products, current efficiency and the number of transferred electrons per CN{sup {minus}} helped to establish a probable reaction scheme. According to this, the process occurs mainly with one-electron transfer, through cyanate and cyanogen as intermediate species. Meanwhile, under conditions where the electrolyte circulates in an open bath and flows successively through the cathodic and the anodic compartments, as in the case of the HCC system, the cyanate could be produced by the direct oxidation through air and/or generated peroxide and CN could be lost as HCN (g).

Dhamo, N. [TU Berlin (Germany). Inst. fuer Metallurgie] [TU Berlin (Germany). Inst. fuer Metallurgie

1996-12-31

311

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

312

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

313

A bacteriophage endolysin-based electrochemical impedance biosensor for the rapid detection of Listeria cells.  

PubMed

The objective of this study was to develop a biosensor using the cell wall binding domain (CBD) of bacteriophage-encoded peptidoglycan hydrolases (endolysin) immobilized on a gold screen printed electrode (SPE) and subsequent electrochemical impedance spectroscopy (EIS) for a rapid and specific detection of Listeria cells. The endolysin was amine-coupled to SPEs using EDC/NHS chemistry. The CBD-based electrode was used to capture and detect the Listeria innocua serovar 6b from pure culture and 2% artificially contaminated milk. In our study, the endolysin functionalized SPEs have been characterized using X-ray photoelectron spectroscopy (XPS). The integration of endolysin-based recognition for specific bacteria and EIS can be used for direct and rapid detection of Listeria cells with high specificity against non-Listeria cells with a limit of detection of 1.1 × 10(4) and 10(5) CFU mL(-1) in pure culture and 2% milk, respectively. PMID:23085745

Tolba, Mona; Ahmed, Minhaz Uddin; Tlili, Chaker; Eichenseher, Fritz; Loessner, Martin J; Zourob, Mohammed

2012-12-21

314

Theoretical and experimental study of a heat pipe in zero-G for electrochemical cell cooling  

SciTech Connect

A new thermal concept to be used with Li/SOCL2 batteries is presented. A thermal model of a grooved nickel heat pipe under uniform heat input is developed, and an experimental assembly is made to simulate the operating conditions in zero-G. It is shown how this new thermal concept can provide the following for the electrochemical cell: thermal cooling by heat pipe, mechanical reinforcement, and current collection. The thermal behavior of a Li/SOCL2 cell under high rate discharge using this concept is compared with that of a traditional concept (aluminum corset around the cell which is fixed to a coldplate). A thermal model is established that uses ESACAP software including about 100 nodes to represent the cell and the aluminum pipe or the heat pipe. 10 refs.

Alain, A.; Ali, S.; Luc, F.J. (Ecole Nationale Superieure de Mecanique et d'Aerotechnique, Poitiers, (France) SAFT, Poitiers, (France))

1991-07-01

315

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

316

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

NASA Astrophysics Data System (ADS)

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

Bora, Debajeet K.; Glans, Per-Anders; Pepper, John; Liu, Yi-Sheng; Du, Chun; Wang, Dunwei; Guo, J.-H.

2014-04-01

317

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

PubMed

An in situ flow electrochemical cell has been designed and fabricated to allow better seal under UHV chamber thus to achieve a good signal to noise ratio in fluorescence yield detection of X-ray absorption spectra for spectroelectrochemical study. The cell also stabilizes the thin silicon nitride membrane window in an effective manner so that the liquid cell remains intact during X-ray absorption experiments. With the improved design of the liquid cell, electrochemical experiments such as cyclic voltammetry have been performed for 10 cycles with a good stability of sample window. Also an operando electrochemical experiment during photoelectrochemistry has been performed on n-type hematite electrode deposited on silicon nitride window. The experiment allows us to observe the formation of two extra electronic transitions before pre edge of O K-edge spectra. PMID:24784592

Bora, Debajeet K; Glans, Per-Anders; Pepper, John; Liu, Yi-Sheng; Du, Chun; Wang, Dunwei; Guo, J-H

2014-04-01

318

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

319

Analytical analysis of the generic SET and RESET characteristics of electrochemical metallization memory cells  

NASA Astrophysics Data System (ADS)

We report on an analytical model which describes the bipolar resistive switching in electrochemical metallization cells. To simulate the resistive switching, we modeled the growth and dissolution of a metallic filament together with electron tunneling between the growing filament and the counter electrode. The model accounts for the controllability of the low resistive state and the RESET current by tuning the SET current. By analytical analysis the relevant conditions for these generic characteristics are identified. In addition, an explanation for the asymmetry in the SET and RESET switching characteristics is presented. The results of the analytical analysis is generalized to all types of ReRAMs.

Menzel, Stephan; Waser, Rainer

2013-10-01

320

Supporting electrodes for solid oxide fuel cells and other electrochemical devices  

DOEpatents

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

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

2008-04-01

321

Electrochemical impregnation and cycle life of lightweight nickel electrodes for nickel-hydrogen cells  

NASA Technical Reports Server (NTRS)

Development of a high specific energy nickel electrode is the main goal of the lightweight nickel electrode program at NASA-Lewis. The approach was to improve the nickel electrode by continuing combined in-house and contract efforts to develop a more efficient and lighter weight electrode for the nickel-hydrogen cell. Lightweight plaques are used as conductive supports for the nickel hydroxide active material. These plaques are commercial products that are fabricated into nickel electrodes by electrochemically impregnating them with active material. The electrodes are life cycle tested in a low Earth orbit regime at 40 and 80 percent depths-of-discharge.

Britton, Doris L.

1990-01-01

322

Electrochemical impregnation and cycle life of lightweight nickel electrodes for nickel-hydrogen cells  

NASA Technical Reports Server (NTRS)

Development of a high specific energy nickel electrode is the main goal of the lightweight nickel electrode program at NASA-Lewis. The approach was to improve the nickel electrode by continuing combined in-house and contract efforts to develop a more efficient and lighter weight electrode for the nickel-hydrogen cell. Lightweight plaques are used as conductive supports for the nickel hydroxide active material. These plaques are commercial products that are fabricated into nickel electrodes by electrochemically impregnating them with active material. The electrodes are life cycle tested in a low earth orbit regime at 40 and 80 percent depths-of-discharge.

Britton, Doris L.

1990-01-01

323

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

324

Electrochemical approach for the development of a simple method for detecting cell apoptosis based on caspase-3 activity.  

PubMed

This paper reports a novel approach for the simple detection of cell apoptosis using an electrochemical technique. This method uses caspase-3 activity as an indicator of apoptosis. Caspase-3 activity was detected with differential plus voltammetry (DPV) as an alternative to conventional spectrometry. In this method, p-nitroaniline (pNA) released from Asp-Glu-Val-Asp-pNA by caspase-3 enzyme reaction was measured with DPV by using a glassy carbon electrode. Using this method, we successfully detected cell apoptosis occurring inside living HepG2 cells without the need for a cell lysis step. This method provides an easy assay procedure and, more importantly, allows a live cell apoptosis detection format. This novel electrochemical apoptosis assay using living cells instead of typically used cell lysates will expand the applicable range of the apoptosis assay to include cell activity assays for drug discovery and cell transplantation medicine. PMID:24798487

Takano, Shinichiro; Shiomoto, Shusaku; Inoue, Kumi Y; Ino, Kosuke; Shiku, Hitoshi; Matsue, Tomokazu

2014-05-20

325

Continuous in situ electrochemical monitoring of doxorubicin efflux from sensitive and drug-resistant cancer cells.  

PubMed

One of the least well understood problems in cancer chemotherapy is the cross-resistance of certain tumor cells to a series of chemically unrelated drugs. Multidrug resistance (MDR) can be attributed to several different biophysical processes, among them increased drug efflux. This has been found to correlate with overexpression of the cell surface 170-kDa P-glycoprotein that actively excludes cytotoxic drugs against their concentration gradient. To better understand MDR, experimental methods are needed to study drug efflux from cancer cells. Continuous measurement of efflux of nonfluorescent drugs on the same cell culture in situ, or assessing efflux from a few cells or even a single cell, is beyond the capabilities of existing technologies. In this work, a carbon fiber (CF) microelectrode is used to monitor efflux of doxorubicin from a monolayer of two cell lines: an auxotrophic mutant of Chinese hamster ovary cells, AUXB1, and its MDR subline, CHRC5. Because doxorubicin is both fluorescent and electroactive, the results could be validated against existing data obtained optically and with other techniques on the same cell lines, with good agreement found. The electrochemical detection, however, is capable of in situ monitoring with high temporal resolution and is suitable for single-cell studies. PMID:9788921

Yi, C; Gratzl, M

1998-11-01

326

Polyaniline doped with dimethyl sulfate as a nucleophilic dopant and its electrochemical properties as an electrode in a lithium secondary battery and a redox supercapacitor.  

PubMed

The physical properties of polyaniline (PAn) powder, doped by nucleophilic doping of dimethyl sulfate (DMS), were characterized, as well as its electrochemical behaviors, to investigate the possibility of a power source device adopting the PAn-DMS electrodes. It is shown that the nucleophilic addition of DMS into PAn concurrently resulted in an increase of the charge transport properties (e.g., electrical conductivity) and enhanced the processability (e.g., lowering of the melting point). The surface structure of PAn-DMS electrodes showed that the compactness of the electrode surface was helpful in increasing the capacity of lithium rechargeable batteries, whereas the porous behavior was valuable to improve the capacitance of a redox supercapacitor. Depending on the power source devices using the lump- and sheet-type PAn-DMS electrodes, the following optimized performances were obtained: more than 80 mA h g-1 after 50 cycles for lithium secondary battery use and approximately 115 F g-1 initially and approximately 94 F g-1 after 5000 cycles at a current density of 2.5 mA cm-2 for application as a redox supercapacitor, which were the highest reported performances for all PAn-based electrodes. PMID:17249816

Ryu, Kwang Sun; Jeong, Sang Kook; Joo, Jinsoo; Kim, Kwang Man

2007-02-01

327

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

328

Self-powered electrochemical memristor based on a biofuel cell--towards memristors integrated with biocomputing systems.  

PubMed

The electrochemical memristor based on a pH-switchable polymer-modified electrode integrated with a biofuel cell was designed and proposed for interfacing between biomolecular information processing and electronic systems. The present approach demonstrates a new application of biofuel cells in information processing systems, rather than for electrical power generation. PMID:24687004

MacVittie, Kevin; Katz, Evgeny

2014-05-14

329

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

330

Method of charging a vented alkaline electrolyte-containing electrochemical cell  

SciTech Connect

The improved method of the present invention comprises charging a vented alkaline electrolyte-containing electrochemical cell employing an electrode pair selected from the group consisting of nickel-zinc, nickel-cadmium, silver-zinc and silver-cadmium and at least periodic measuring the charging efficiency of the cell by determining the rate of gas evolution from the cell. The charging of the cell is terminated when the charging efficiency substantially decreases, signifying the cell having reached an about full charge. The charging efficiency at that point normally substantially decreases to a value of about 0.5 + or - 0.2. In the alkaline electrolyte-containing cells, the charging efficiency is determined according to the formula E 1-(15.8/i) V wherein E is the charging efficiency, I is the current in amperes and V is the gas generation rate in the cell in cc per second. The improved method prevents overcharging of the cell and accurately determines when an about full charge is reached. Accordingly, charging can be carried out without risk of damage to the cell and with the greatest efficiency.

Seiger, H.N.; Terjesen, T.T.

1980-04-15

331

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

332

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

333

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

Microsoft Academic Search

The relationship between anode microbial characteristics and electrochemical parameters in microbial fuel cells (MFCs) was analyzed by time-course sampling of parallel single-bottle MFCs operated under identical conditions. While voltage stabilized within 4days, anode biofilms continued growing during the six-week operation. Viable cell density increased asymptotically, but membrane-compromised cells accumulated steadily from only 9% of total cells on day 3 to

Zhiyong Ren; Ramaraja P. Ramasamy; Susan Red Cloud-Owen; Hengjing Yan; Matthew M. Mench; John M. Regan

2011-01-01

334

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.

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

2014-01-01

335

Bond nature of active metal ions in SiO2-based electrochemical metallization memory cells  

NASA Astrophysics Data System (ADS)

Electrochemical metallization cells are candidates for the next-generation non-volatile memory devices based on resistive switching. Despite the intensive studies in recent years a microscopic model of the processes in these nanoscale electrochemical systems is still missing and the physicochemical properties of the active metal ions have been rarely reported. We examined the bonding characteristics of Cuz+ and Ag+ ions in SiO2-based cells using soft X-ray absorption spectroscopy. Whereas the Ag/SiO2 interfaces showed no chemical interaction of Ag ions, the Cu/SiO2 showed clear signatures of partial oxidation into two ionic species of Cu2+ and Cu+. The analyses on the orbital hybridization strength evidently showed that the Cu2+-O2- bonds in SiO2 are much weaker than the Cu+-O2- bonds, analogous to the case of bulk CuO and Cu2O. This suggests that the Cu2+ ions should be more mobile and with a dominating role in the process of resistive switching.

Cho, Deok-Yong; Tappertzhofen, Stefan; Waser, Rainer; Valov, Ilia

2013-02-01

336

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

337

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

338

Secondary malignant giant-cell tumor of bone. Clinicopathological assessment of nineteen patients  

SciTech Connect

Twenty-six patients who had a malignant giant-cell tumor of bone--a sarcoma either juxtaposed to a zone of typical benign giant-cell tumor or occurring at the site of a previously documented benign giant-cell tumor--have been seen at the Mayo Clinic. Of the twenty-six tumors, nineteen were secondary to a previous attempt at local control of a benign giant-cell tumor. All but one of these nineteen patients with a secondary tumor had received therapeutic irradiation four to thirty-nine years earlier. The nature and duration of the symptoms and the sites of predilection of the malignant giant-cell tumors were the same as for benign giant-cell tumor. Fibrosarcoma occurred three times as frequently as osteosarcoma. The best results of treatment of the secondary sarcoma were obtained with early ablation.

Rock, M.G.; Sim, F.H.; Unni, K.K.; Witrak, G.A.; Frassica, F.J.; Schray, M.F.; Beabout, J.W.; Dahlin, D.C.

1986-09-01

339

The dynamic interplay of plasma membrane domains and cortical microtubules in secondary cell wall patterning  

PubMed Central

Patterning of the cellulosic cell wall underlies the shape and function of plant cells. The cortical microtubule array plays a central role in the regulation of cell wall patterns. However, the regulatory mechanisms by which secondary cell wall patterns are established through cortical microtubules remain to be fully determined. Our recent study in xylem vessel cells revealed that a mutual inhibitory interaction between cortical microtubules and distinct plasma membrane domains leads to distinctive patterning in secondary cell walls. Our research revealed that the recycling of active and inactive ROP proteins by a specific GAP and GEF pair establishes distinct de novo plasma membrane domains. Active ROP recruits a plant-specific microtubule-associated protein, MIDD1, which mediates the mutual interaction between cortical microtubules and plasma membrane domains. In this mini review, we summarize recent research regarding secondary wall patterning, with a focus on the emerging interplay between plasma membrane domains and cortical microtubules through MIDD1 and ROP.

Oda, Yoshihisa; Fukuda, Hiroo

2013-01-01

340

New Li-alloy electrode for Li-alloy/metal sulfide cells  

SciTech Connect

The present invention relates to electrodes for use in secondary electrochemical cells. More particularly, it concerns a method of making a negative electrode composition, the electrode composition made thereby and the secondary electrochemical cell containing the electrode, wherein the negative electrode composition includes a lithium alloy including silicon and nickel.

Kaun, T.D.

1994-12-31

341

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

342

Significantly Better Prognosis for Patients with Primary Plasma Cell Leukemia than for Patients with Secondary Plasma Cell Leukemia  

Microsoft Academic Search

Plasma cell leukemia (PCL) is a rare variant of multiple myeloma (MM). Patients may either present de novo (primary PCL), or PCL may occur during the course of MM (secondary PCL). We compared the laboratory and clinical findings of both primary and secondary PCL and MM to elucidate their natural history and the relationship among these entities. Ten cases of

Choong Hwan Cha; Chan Jeoung Park; Joo Ryung Huh; Hyun Sook Chi; Cheol Won Suh; Yoon Koo Kang

2007-01-01

343

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

NASA Technical Reports Server (NTRS)

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

Baldwin, Richard S.; Bennett, William R.

2007-01-01

344

Analysis of secondary lithium cells with sulfur dioxide based electrolytes  

Microsoft Academic Search

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

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

1992-01-01

345

Electrodes and electrochemical storage cells utilizing tin-modified active materials  

DOEpatents

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

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

1995-01-01

346

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

NASA Astrophysics Data System (ADS)

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

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

347

Distinct CD4+ helper T cells involved in primary and secondary responses to infection  

PubMed Central

Helper T cells are critical for protective immunity, CD8+ T-cell memory, and CD4+ recall responses, but whether the same or distinct CD4+ T cells are involved in these responses has not been established. Here we describe two CD4+ T cells, LLO118 and LLO56, specific for an immunodominant Listeria monocytogenes epitope, with dramatically different responses to primary and secondary infection. Comparing in vivo responses, LLO118 T cells proliferate more strongly to primary infection, whereas surprisingly, LLO56 has a superior CD4+ recall response to secondary infection. LLO118 T cells provide more robust help for CD8+ T-cell responses to secondary infection than LLO56. We found no detectable differences in antigen sensitivity, but naive LLO118 T cells have much lower levels of CD5 and their T-cell receptor levels are dramatically down-regulated after their strong primary response. Thus, distinct CD4+ helper T cells are specialized to help either in primary or secondary responses to infection.

Weber, K. Scott; Li, Qi-Jing; Persaud, Stephen P.; Campbell, Jeff D.; Davis, Mark M.; Allen, Paul M.

2012-01-01

348

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

349

Improving Microchip Capillary Electrophoresis with Electrochemical Detection Using a Bubble Cell and Sample Stacking Techniques  

PubMed Central

Two efforts to improve the sensitivity and limits of detection for MCE with electrochemical detection are presented here. One is the implementation of a capillary expansion (bubble cell) at the detection zone to increase the exposed working electrode surface area. Bubble cell widths were varied from 1× to 10× the separation channel width (50 ?m) to investigate the effects of electrode surface area on detection sensitivity, LOD, and separation efficiency. Improved detection sensitivity and decreased detection limits were obtained with increased bubble cell width, and LODs of dopamine and catechol detected in a 5× bubble cell were 25 nM and 50 nM, respectively. Meanwhile, fluorescent imaging results demonstrated ~8% and ~12% loss in separation efficiency in 4× and 5× bubble cell, respectively. Another effort for reducing the LOD involves using field amplified sample injection (FASI) for gated injection and field amplified sample stacking (FASS) for hydrodynamic injection. Stacking effects are shown for both methods using amperometric detection and pulsed amperometric detection (PAD). The LODs of dopamine in a 4× bubble cell were 8 nM and 20 nM using FASI and FASS, respectively. However, improved LODs were not obtained for anionic analytes using either stacking technique.

Guan, Qian; Henry, Charles S.

2010-01-01

350

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

351

Electrochemical single-cell gene-expression assay combining dielectrophoretic manipulation with secreted alkaline phosphatase reporter system  

Microsoft Academic Search

Scanning electrochemical microscopy (SECM) was used for the analysis of single-cell gene-expression signals on the basis of a reporter system. We microfabricated a single-cell array on an Indium tin oxide (ITO) electrode comprising 4×4 SU-8 microwells with a diameter of 30?m and a depth of 25?m. HeLa cells transfected with plasmid vectors encoding the secreted alkaline phosphatase (SEAP) were seeded

Tatsuya Murata; Tomoyuki Yasukawa; Hitoshi Shiku; Tomokazu Matsue

2009-01-01

352

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

Microsoft Academic Search

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,

Grant Hawkes; James E. OBrien

2008-01-01

353

T Cell-dependent Antitumor Immunity Mediated by Secondary Lymphoid Tissue Chemokine: Augmentation of Dendritic Cell-based Immunotherapy1  

Microsoft Academic Search

Secondary lymphoid tissue chemokine (SLC) is a CC chemokine that is selective in its recruitment of naive T cells and dendritic cells (DCs). In the lymph node, SLC is believed to play an important role in the initiation of an immune response by colocalizing naive T cells with DC-presenting antigen. Here, we used SLC as a treatment for tumors established

Christopher J. Kirk; Dennis Hartigan-O; Brian J. Nickoloff; Jeffrey S. Chamberlain; Martin Giedlin; Lea Aukerman; James J. Mule

354

Electrochemical differential photoacoustic cell to study in situ the growing process of porous materials.  

PubMed

In order to study in situ the growing process of porous materials, a new electrochemical differential photoacoustic cell (DPC) was developed. This system allows to obtain the thermal signals coming from the growing process of the pores without the external noise component. The DPC is a good system to growth porous silicon and study their growing process with reproducibility. The porous silicon samples were obtained by using electrochemical etching of (100) n-type silicon wafers with different nominal resistivity values in the range of 1-25 Omega cm. The samples were formed in a solution of hydrofluoric acid and ethanol having a composition ratio of 1:1 in volume with etching voltage of 10 V and an etching time of 2 min using back illumination provided by a laser beam with a wavelength of 808 nm. The porous samples were characterized by means of Raman microscopy, x-ray diffraction, and scanning electron microscopy. The crystallite sizes of the samples were obtained through the analysis of the micro-Raman spectra using a phonon confinement model, and the analysis of the x-ray diffractograms. PMID:20113107

Gutiérrez, Adriana; Giraldo, Jairo; Velázquez-Hernández, Rubén; Mendoza-López, Maria Luisa; Espinosa-Arbeláez, Diego G; del Real, Alicia; Rodríguez-García, Mario E

2010-01-01

355

Carbon-ring microelectrode arrays for electrochemical imaging of single cell exocytosis: fabrication and characterization.  

PubMed

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

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

2012-03-20

356

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

PubMed Central

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

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

2012-01-01

357

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

358

Circulating cells as predictors of secondary manifestations of cardiovascular disease: design of the CIRCULATING CELLS study.  

PubMed

Biomarkers for primary or secondary risk prediction of cardiovascular disease (CVD) are urgently needed to improve individual treatment and clinical trial design. The vast majority of biomarker discovery studies has concentrated on plasma/serum as an easily accessible source. Although numerous markers have been identified, their added predictive value on top of traditional risk factors has been limited, as the biological specimen does not specifically reflect expression profiles related with CVD progression and because the signal is often diluted by marker release from other organs. In contrast to serum markers, circulating cells serve as indicators of the actual disease state due to their active role in the pathogenesis of CVD and are responsible for the majority of secreted biomarkers. Therefore, the CIRCULATING CELLS study was initiated, focusing on the cellular effectors of atherosclerosis in the circulation. In total, 714 patients with coronary artery disease (CAD) symptoms were included. Blood cell fractions (monocytes, T-lymphocytes, platelets, granulocytes, PBMC) of all individual patients were isolated and stored for analysis. Concomitantly, extensive flow cytometric characterization of these populations was performed. From each patient, a detailed clinical profile together with extensive questionnaires about medical history and life style was obtained. Various high-throughput -omics approaches (protein, mRNA, miRNA) are currently being undertaken. Data will be integrated with advanced bioinformatics for discovery and validation of secondary risk markers for adverse events. Overall, the CIRCULATING CELLS study grants the interesting possibility that it will both identify novel biomarkers and provide useful insights into the pathophysiology of CAD in patients. PMID:23975238

Hoefer, Imo E; Sels, Jan-Willem; Jukema, J Wouter; Bergheanu, Sandrin; Biessen, Erik; McClellan, Elizabeth; Daemen, Mat; Doevendans, Pieter; de Groot, Philip; Hillaert, Marieke; Horsman, Sebastiaan; Ilhan, Mustafa; Kuiper, Johan; Pijls, Nico; Redekop, Ken; van der Spek, Peter; Stubbs, Andrew; van de Veer, Eric; Waltenberger, Johannes; van Zonneveld, Anton-Jan; Pasterkamp, Gerard

2013-11-01

359

Engineering the Oryza sativa cell wall with rice NAC transcription factors regulating secondary wall formation  

PubMed Central

Plant tissues that require structural rigidity synthesize a thick, strong secondary cell wall of lignin, cellulose and hemicelluloses in a complicated bridged structure. Master regulators of secondary wall synthesis were identified in dicots, and orthologs of these regulators have been identified in monocots, but regulation of secondary cell wall formation in monocots has not been extensively studied. Here we demonstrate that the rice transcription factors SECONDARY WALL NAC DOMAIN PROTEINs (SWNs) can regulate secondary wall formation in rice (Oryza sativa) and are potentially useful for engineering the monocot cell wall. The OsSWN1 promoter is highly active in sclerenchymatous cells of the leaf blade and less active in xylem cells. By contrast, the OsSWN2 promoter is highly active in xylem cells and less active in sclerenchymatous cells. OsSWN2 splicing variants encode two proteins; the shorter protein (OsSWN2S) has very low transcriptional activation ability, but the longer protein (OsSWN2L) and OsSWN1 have strong transcriptional activation ability. In rice, expression of an OsSWN2S chimeric repressor, driven by the OsSWN2 promoter, resulted in stunted growth and para-wilting (leaf rolling and browning under normal water conditions) due to impaired vascular vessels. The same OsSWN2S chimeric repressor, driven by the OsSWN1 promoter, caused a reduction of cell wall thickening in sclerenchymatous cells, a drooping leaf phenotype, reduced lignin and xylose contents and increased digestibility as forage. These data suggest that OsSWNs regulate secondary wall formation in rice and manipulation of OsSWNs may enable improvements in monocotyledonous crops for forage or biofuel applications.

Yoshida, Kouki; Sakamoto, Shingo; Kawai, Tetsushi; Kobayashi, Yoshinori; Sato, Kazuhito; Ichinose, Yasunori; Yaoi, Katsuro; Akiyoshi-Endo, Miho; Sato, Hiroko; Takamizo, Tadashi; Ohme-Takagi, Masaru; Mitsuda, Nobutaka

2013-01-01

360

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

361

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

362

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.

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

2010-01-01

363

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

364

Membrane-based electrochemical nanobiosensor for Escherichia coli detection and analysis of cells viability.  

PubMed

A sensitive and selective membrane-based electrochemical nanobiosensor is developed for specific quantitative label-free detection of Escherichia coli (E. coli) cells and analysis of viable but nonculturable (VBNC) E. coli cells which remain mostly undetected using current methods. The sensing mechanism relies on the blocking of nanochannels of a nanoporous alumina-membrane modified electrode, upon the formation of immune complexes at the nanoporous membrane. The resulting obstacle to diffusive mass transfer of a redox probe in the analysis solution to the underlying platinum electrode reduces the Faradaic signal response of the biosensor, measured using cyclic voltammetry. Antibody loading under conditions of varying antibody concentrations and pHs are optimized. The biosensor gives a low detection limit of 22 cfu mL(-1) (R(2) = 0.999) over a wide linear working range of 10 to 10(6) cfu mL(-1). It is specific toward E. coli with minimal cross-reactivity to two other pathogenic bacteria (commonly found in waters). Relative standard deviation (RSD) for triplicate measurements of 2.5% indicates reasonably useful level of reproducibility. Differentiation of live, VBNC, and dead cells are carried out after the cell capture and quantitation step, by simple monitoring of the cells' enzyme activity using the same redox probe in the analysis solution, in the presence of glucose. PMID:21688778

Cheng, Ming Soon; Lau, Suk Hiang; Chow, Vincent T; Toh, Chee-Seng

2011-08-01

365

Production of hydrogen by the electrochemical reforming of glycerol–water solutions in a PEM electrolysis cell  

Microsoft Academic Search

An alternative method for producing hydrogen from renewable resources is proposed. Electrochemical reforming of glycerol solution in a proton exchange membrane (PEM) electrolysis cell is reported. The anode catalyst was composed of Pt on Ru–Ir oxide with a catalyst loading of 3mgcm?2 on Nafion. Part of the energy carried by the produced hydrogen is supplied by the glycerol (82%) and

A. T. Marshall; R. G. Haverkamp

2008-01-01

366

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

PubMed

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

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

2014-05-28

367

Production and excretion of secondary metabolites by plant cell cultures of Tagetes  

Microsoft Academic Search

In this thesis, the results are presented of several approaches to improve the production and excretion of thiophenes by cell cultures or hairy roots of Tagetes spp.In chapter one, most of the techniques to improve the production and\\/or excretion of secondary metabolites with plant cell cultures are discussed in a literature survey. From this chapter, it becomes clear that to

R. M. Buitelaar

1991-01-01

368

A Battery of Transcription Factors Involved in the Regulation of Secondary Cell Wall Biosynthesis in Arabidopsis  

PubMed Central

SECONDARY WALL-ASSOCIATED NAC DOMAIN PROTEIN1 (SND1) is a master transcriptional switch activating the developmental program of secondary wall biosynthesis. Here, we demonstrate that a battery of SND1-regulated transcription factors is required for normal secondary wall biosynthesis in Arabidopsis thaliana. The expression of 11 SND1-regulated transcription factors, namely, SND2, SND3, MYB103, MYB85, MYB52, MYB54, MYB69, MYB42, MYB43, MYB20, and KNAT7 (a Knotted1-like homeodomain protein), was developmentally associated with cells undergoing secondary wall thickening. Of these, dominant repression of SND2, SND3, MYB103, MYB85, MYB52, MYB54, and KNAT7 significantly reduced secondary wall thickening in fiber cells. Overexpression of SND2, SND3, and MYB103 increased secondary wall thickening in fibers, and overexpression of MYB85 led to ectopic deposition of lignin in epidermal and cortical cells in stems. Furthermore, SND2, SND3, MYB103, MYB85, MYB52, and MYB54 were able to induce secondary wall biosynthetic genes. Direct target analysis using the estrogen-inducible system revealed that MYB46, SND3, MYB103, and KNAT7 were direct targets of SND1 and also of its close homologs, NST1, NST2, and vessel-specific VND6 and VND7. Together, these results demonstrate that a transcriptional network consisting of SND1 and its downstream targets is involved in regulating secondary wall biosynthesis in fibers and that NST1, NST2, VND6, and VND7 are functional homologs of SND1 that regulate the same downstream targets in different cell types.

Zhong, Ruiqin; Lee, Chanhui; Zhou, Jianli; McCarthy, Ryan L.; Ye, Zheng-Hua

2008-01-01

369

Clear cell chondrosarcoma with secondary aneurysmal bone cyst changes.  

PubMed

Clear cell chondrosarcoma is a rare cartilaginous tumour of low-grade malignancy. Although it has a characteristic histological appearance, its radiological features and clinical presentation often mimic a benign lesion. Herein, we describe the case of a patient with a clear cell chondrosarcoma of the right proximal femur that had an atypical appearance of chronic avascular necrosis on initial plain radiographs, which made preoperative diagnosis a challenge. In addition, the tumour also had extensive areas of aneurysmal bone cyst-like changes, which is not only a rare histologic phenomenon in clear cell chondrosarcoma, but also a confounding factor in the interpretation of the radiologic findings. PMID:24664395

Tay, Timothy; Wong, Steven Bak Siew; Sittampalam, Kesavan so; Lie, Denny Tjiauw Tjoen

2014-03-01

370

Capacity-cycle life behavior in secondary lithium cells  

NASA Technical Reports Server (NTRS)

The practical utilization of high energy density rechargeable lithium cells is dependent upon maintaining high capacity for the duration of the required cycle life. However, a critical, yet generic problem with room temperature lithium systems is that the capacity often declines considerably during the early stages of cycling. The results of our studies are reported on electrolyte degradation which is observed after cells have undergone 300 and 700 deep cycles with 3-methylsulfolane- and 2-methyltetrahydrofuran-LiAsF6 electrolytes, respectively.

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

1985-01-01

371

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

DOEpatents

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

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

1981-01-01

372

SOLID OXIDE FUEL CELL CATHODES: Polarization Mechanisms and Modeling of the Electrochemical Performance  

NASA Astrophysics Data System (ADS)

Several recent experimental and numerical investigations have contributed to the improved understanding of the electrochemical mechanisms taking place at solid oxide fuel cell (SOFC) cathodes and yielded valuable information on the relationships between alterable parameters (geometry/material) and the cathodic polarization resistance. Efforts to reduce the polarization resistance in SOFCs can benefit from these results, and some important aspects of the corresponding studies are reviewed. Experimental results, particularly measurements using geometrically well-defined Sr-doped LaMnO3 (LSM) cathodes, are discussed. In regard to simulations, the different levels of sophistication used in SOFC electrode modeling studies are summarized and compared. Exemplary simulations of mixed conducting cathodes that show the capabilities and limits of different modeling levels are described.

Fleig, Jurgen

2003-08-01

373

An evaluation of electrochemical concentration Cell (ECC) sonde measurements of atmospheric ozone  

NASA Technical Reports Server (NTRS)

Using Dobson spectrophotometer measurements of total ozone as a comparison, an analysis of the electrochemical concentration cell (ECC) ozonesonde's measurement accuracy is presented. Days of conjunctive ECC-Dobson observations (from 1970 to 1976 at Wallops Flight Center) provide a set of 123 pairs of total ozone values. Sample set statistics are generated with means and standard deviations of total ozone values and differences being noted. An in-depth study of factors such as time assumptions used in calculating residual ozone, and other possible sources of errors are examined. A study of ECC ozone profiles is also presented with an evaluation of sonde measurement of seasonal trends, altitude or peak ozone concentration, and other important ozone parameters. Short-period changes in total ozone using Dobson data during the observational period are also described.

Geraci, M. J.; Luers, J. K.

1978-01-01

374

Electrochemically Reduced Graphene Oxide Multilayer Films as Efficient Counter Electrode for Dye-Sensitized Solar Cells  

PubMed Central

We report on a new counter electrode for dye-sensitized solar cells (DSCs), which is prepared using layer-by-layer assembly of negatively charged graphene oxide and positively charged poly (diallyldimethylammonium chloride) followed by an electrochemical reduction procedure. The DSC devises using the heteroleptic Ru complex C106TBA as sensitizer and this new counter electrode reach power conversion efficiencies of 9.5% and 7.6% in conjunction with low volatility and solvent free ionic liquid electrolytes, respectively. The new counter electrode exhibits good durability (60°C for 1000?h in a solar simulator, 100?mW cm?2) during the accelerated tests when used in combination with an ionic liquid electrolyte. This work identifies a new class of electro-catalysts with potential for low cost photovoltaic devices.

Xu, Xiaobao; Huang, Dekang; Cao, Kun; Wang, Mingkui; Zakeeruddin, Shaik M.; Gratzel, Michael

2013-01-01

375

Electrochemically reduced graphene oxide multilayer films as efficient counter electrode for dye-sensitized solar cells.  

PubMed

We report on a new counter electrode for dye-sensitized solar cells (DSCs), which is prepared using layer-by-layer assembly of negatively charged graphene oxide and positively charged poly (diallyldimethylammonium chloride) followed by an electrochemical reduction procedure. The DSC devises using the heteroleptic Ru complex C106TBA as sensitizer and this new counter electrode reach power conversion efficiencies of 9.5% and 7.6% in conjunction with low volatility and solvent free ionic liquid electrolytes, respectively. The new counter electrode exhibits good durability (60°C for 1000?h in a solar simulator, 100?mW cm(-2)) during the accelerated tests when used in combination with an ionic liquid electrolyte. This work identifies a new class of electro-catalysts with potential for low cost photovoltaic devices. PMID:23508212

Xu, Xiaobao; Huang, Dekang; Cao, Kun; Wang, Mingkui; Zakeeruddin, Shaik M; Grätzel, Michael

2013-01-01

376

Nab2 regulates secondary CD8+ T-cell responses through control of TRAIL expression.  

PubMed

CD4(+) Th cells are pivotal for the generation and maintenance of CD8(+) T-cell responses. "Helped" CD8(+) T cells receive signals during priming that prevent the induction of the proapoptotic molecule TNF-related apoptosis-inducing ligand (TRAIL) during reactivation, thereby enabling robust secondary expansion. Conversely, "helpless" CD8(+) T cells primed in the absence of Th induce TRAIL expression after restimulation and undergo activation-induced cell death. In the present study, we investigated the molecular basis for the differential regulation of TRAIL in helped versus helpless CD8(+) T cells by comparing their transcriptional profiles, and have identified a transcriptional corepressor, NGFI-A binding protein 2 (Nab2), that is selectively induced in helped CD8(+) T cells. Enforced expression of Nab2 prevents TRAIL induction after restimulation of primary helpless CD8(+) T cells, and expression of a dominant-negative form of Nab2 in helped CD8(+) T cells impairs their secondary proliferative response that is reversible by TRAIL blockade. Finally, we observe that the CD8(+) T-cell autocrine growth factor IL-2 coordinately increases Nab2 expression and decreases TRAIL expression. These findings identify Nab2 as a mediator of Th-dependent CD8(+) T-cell memory responses through the regulation of TRAIL and the promotion of secondary expansion, and suggest a mechanism through which this operates. PMID:22128144

Wolkers, Monika C; Gerlach, Carmen; Arens, Ramon; Janssen, Edith M; Fitzgerald, Patrick; Schumacher, Ton N; Medema, Jan Paul; Green, Douglas R; Schoenberger, Stephen P

2012-01-19

377

Electrochemical investigation of a microbial solar cell reveals a nonphotosynthetic biocathode catalyst.  

PubMed

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

Strycharz-Glaven, Sarah M; Glaven, Richard H; Wang, Zheng; Zhou, Jing; Vora, Gary J; Tender, Leonard M

2013-07-01

378

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.

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

2013-01-01

379

Probing the chemistry of nickel/metal hydride battery cells using electrochemical impedance spectroscopy  

NASA Technical Reports Server (NTRS)

Electrochemical Impedance Spectroscopy (EIS) is a valuable tool for investigating the chemical and physical processes occurring at electrode surfaces. It offers information about electron transfer at interfaces, kinetics of reactions, and diffusion characteristics of the bulk phase between the electrodes. For battery cells, this technique offers another advantage in that it can be done without taking the battery apart. This non-destructive analysis technique can thus be used to gain a better understanding of the processes occurring within a battery cell. This also raises the possibility of improvements in battery design and identification or prediction of battery characteristics useful in industry and aerospace applications. EIS as a technique is powerful and capable of yielding significant information about the cell, but it also requires that the many parameters under investigation can be resolved. This implies an understanding of the processes occurring in a battery cell. Many battery types were surveyed in this work, but the main emphasis was on nickel/metal hydride batteries.

Isaac, Bryan J.

1994-01-01

380

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.

2014-01-01

381

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.

Williams, Matthew A.

2014-01-01

382

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

PubMed

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

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

2014-05-01

383

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

384

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

385

Effect of Congo Red on Electrochemical Characteristics of the Bioanode of Microbial Fuel Cell Explored for Simultaneous Azo Dye-containing Wastewater Treatment and Electricity Generation  

Microsoft Academic Search

To exploit the outstanding ability of microbial fuel cell (MFC) for simultaneous treatment of azo dye - polluted wastewater and bioelectricity generation, the effect of a representative azo dye - Congo red on the electrochemical characteristics of the bioanode of an air-cathode single chambered MFC was investigated in detail. The electrochemical impedance spectroscopy (EIS) showed that decolorization of different concentration

Jian Sun; Bin Hou; Pingya Zhang; Yong-you Hu

2011-01-01

386

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

387

Comparative study of the expression of proteins involved in the cell cycle in renal secondary hyperparathyroidism  

Microsoft Academic Search

Comparative study of the expression of proteins involved in the cell cycle in renal secondary hyperparathyroidism.BackgroundIn renal hyperparathyroidism, parathyroid cell proliferation seems to play a key role in the progression of the disease. Therefore, G1\\/S transition, a main cell cycle regulatory step, could be deregulated in these patients.MethodsOne hundred and one parathyroid glands, taken from parathyroidectomies performed on 41 patients

José A Alcázar; Jose R. Polo; Juan C. Tardio; Javier Anguita; Juan C. Martinez-Montero; Rosa Jofré; Francisco J. Garcia-Criado; Javier Menárguez

2003-01-01

388

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.

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

389

The microstructure of secondary lymphoid organs that support immune cell trafficking.  

PubMed

Immune cell trafficking in the secondary lymphoid organs is crucial for an effective immune response. Recirculating T cells constantly patrol not only secondary lymphoid organs but also the whole peripheral organs. Thoracic duct lymphocytes represent an ideal cell source for analyzing T cell trafficking: high endothelial venules (HEVs) allow recirculating lymphocytes to transmigrate from the blood directly, and recirculating T cells form a cluster with dendritic cells (DCs) to survey antigen invasions even in a steady state. This cluster becomes an actual site for the antigen presentation when DCs have captured antigens. On activation, effector and memory T cells differentiate into several subsets that have different trafficking molecules and patterns. DCs also migrate actively in a manner depending upon their maturational stages. Danger signals induce the recruitment of several DC precursor subsets with different trafficking patterns and functions. In this review, we describe general and specialized structures of the secondary lymphoid organs for the trafficking of T cells and DCs by a multicolor immunoenzyme staining technique. The lymph nodes, spleen, and Peyer's patches of rats were selected as the major representatives. In vivo trafficking of subsets of T cells and DCs within these organs under steady or emergency states are shown and discussed, and unsolved questions and future prospects are also considered. PMID:21471663

Matsuno, Kenjiro; Ueta, Hisashi; Shu, Zhou; Xue-Dong, Xu; Sawanobori, Yasushi; Kitazawa, Yusuke; Bin, Yu; Yamashita, Masaki; Shi, Changde

2010-01-01

390

Renal cell carcinoma with secondary hemophagocytic syndrome: A case report  

PubMed Central

A patient with a suspected malignancy and pancytopenia warrants much consideration. Most clinicians would consider bone marrow infiltrative process, heralding a grave prognosis. However, rare occurrence of hemophagocytic lymphohistiocytosis is another diagnostic possibility we should keep in mind. The treatment choices and overall prognosis may differ from patients without hemophagocytosis. We present a case of incidentally found advanced renal cell carcinoma (RCC) concurrent with hemophagocytosis process in the bone marrow. We also discuss the importance of this finding.

Chao, Chia-Ter; Kao, Chih-Chin; Lee, Szu-Ying; Ho, Shu-Jung; Jhuang, Ying-Jheng; Li, Lars Hung-Yuan; Kao, Tze-Wah

2012-01-01

391

Definition of chemical and electrochemical properties of a fuel cell electrolyte  

NASA Astrophysics Data System (ADS)

The present research is oriented toward the task of developing an improved electrolyte for the direct hydrocarbon-air fuel cell. The electrochemical behavior of methanesulfonic acid, ethanesulfonic acid, and sulfoacetic acid as fuel cell electrolytes was studied in a half cell at various temperatures. The rate of electro-oxidation of hydrogen at 115 degrees was very high in methanesulfonic acid and sulfoacetic acids. The rate of the electro-oxidation of propane in methanesulfonic acid at 80 C and 115 C was low. Further, there is evidence for adsorption of these acids on the platinum electrode. Sulfoacetic acid with H2 has supported about two times higher current density than trifluoromethanesulfonic acid monohydrate, but, attempts to purify the compound were unsuccessful. It was concluded that anhydrous sulfonic acids are not good electrolytes; water solutions are required. Sulfonic acids containing unprotected C-H bonds are adsorbed on platinum and probably decompose during electrolysis. A completely substituted sulfonic acid would be the preferred electrolyte.

Ahmad, J.; Foley, R. T.

1980-01-01

392

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.

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

2009-01-01

393

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, Reinhard (Nussloch, DE); Nelson, Paul A. (Wheaton, IL); Shimotake, Hiroshi (Hinsdale, IL); Battles, James E. (Oak Forest, IL)

1985-01-01

394

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

395

Secondary hair cells and afferent neurones of the squid statocyst receive both inhibitory and excitatory efferent inputs  

Microsoft Academic Search

Intracellular recordings were obtained from the hair cells and afferent neurones of the angular acceleration receptor system of the statocyst of the squid,Alloteuthis subulata. Electrical stimulation of the efferent fibres in the crista nerve (minor) evoked responses in all of the secondary hair cells recorded from (n=211). 48% of the secondary air cells responded with a small depolarization, 15% with

R. Williamson

1989-01-01

396

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

397

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

398

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

399

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

400

Comparative structure and biomechanics of plant primary and secondary cell walls  

PubMed Central

Recent insights into the physical biology of plant cell walls are reviewed, summarizing the essential differences between primary and secondary cell walls and identifying crucial gaps in our knowledge of their structure and biomechanics. Unexpected parallels are identified between the mechanism of expansion of primary cell walls during growth and the mechanisms by which hydrated wood deforms under external tension. There is a particular need to revise current “cartoons” of plant cell walls to be more consistent with data from diverse approaches and to go beyond summarizing limited aspects of cell walls, serving instead as guides for future experiments and for the application of new techniques.

Cosgrove, Daniel J.; Jarvis, Michael C.

2012-01-01

401

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

PubMed

Release of neurotransmitters and hormones by calcium 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 ?m×300 ?m) and utilized these for quantitative detection of catecholamine release from adrenal chromaffin cells trapped in a microfluidic network. The IrOx electrodes show a linear response to norepinephrine in the range of 0-400 ?M, with a sensitivity of 23.1±0.5 mA/M mm(2). 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 device and stimulated by rapid perfusion with high potassium (50mM) containing Tyrode's solution at a flow rate of 1 nL/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 cell culture volume of ~52 ?M. 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 chromaffin cells. PMID:22398270

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

2012-04-15

402

A wound-type lithium/polyaniline secondary cell  

NASA Astrophysics Data System (ADS)

A wound-type cell with a polyaniline (PAn) positive electrode, a LiClON4-propylene carbonate (PC) electrolyte, and a lithium-foil negative electrode is constructed. The two electrodes are separated by a polypropylene separator. The PAn is deposited on carbon felt from a HClON4 solution containing aniline by galvanostatic or potentiostatic electrolysis. Using cyclic voltammetry charge/discharge cycles and charge/retention tests, the following results are obtained: (1) reversibility of the charge/discharge reaction of the PAn electrode is very good; (2) more than 50 charge/discharge cycles at 80 percent charge/discharge efficiency and 260 W h/kg discharge energy density can be achieved at 50 mA between 2 and 4 V; (3) the open-circuit voltage and the capacity retention of the battery after storage at open-circuit for 60 days are 3.4 V and 33 percent, respectively.

Li, Changzhi; Zhang, Borong; Wang, Baochen

1992-07-01

403

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

404

A bioactive polymer grafted on titanium oxide layer obtained by electrochemical oxidation. Improvement of cell response.  

PubMed

The anchorage failure of titanium implants in human body is mainly due to biointegration problem. The proposed solution is to graft a bioactive polymer at the surface of the implant in order to improve and control the interactions with the living system. In this paper, we describe the grafting of poly sodium styrene sulfonate on titanium surface by using a silanization reaction. The key point is to increase the TiOH content at the surface of the implant which can react with methoxy silane groups of 3-methacryloxypropyltrimethoxysilane (MPS). Two procedures were used: chemical oxidation and electrochemical oxidation. The last oxidation procedure was carried out in two different electrolytes: oxalic acid and methanol. These different oxidation methods allow controlling the roughness and the depth of the oxide layer. The methacryloyl group of MPS grafted at the titanium surface by silanization reaction is copolymerized with sodium styrene sulfonate using a thermal initiator able to produce radicals by heating. Colorimetric method, ATR-FTIR, XPS techniques and contact angle measurements were applied to characterize the surfaces. MG63 osteoblastic cell response was studied on polished, oxidized and grafted titanium samples. Cell adhesion, Alkaline Phosphatase activity and calcium nodules formation were significantly enhanced on grafted titanium surfaces compared to un-modified surfaces. PMID:19842019

Hélary, Gérard; Noirclère, Flavie; Mayingi, Josselin; Bacroix, Brigitte; Migonney, Véronique

2010-02-01

405

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

PubMed

The production of reactive oxygen species (ROS) in the body has been shown to play a significant role in the development and progression of numerous diseases. This makes it important to develop a method of detection for hydrogen peroxide (H2O2), the most stable ROS. Several methods such as the use of fluorescent probes and electrochemistry have been utilized in the past to detect the imbalance in ROS levels generated from injured or stimulated cells. An imbalance in the levels of ROS leads to a state of oxidative stress within the body. Different enzymes such as horseradish peroxidase (HRP) and superoxide dismutase have been used in the detection of ROS. HRP is commonly used as the biorecognition element in many H2O2 sensors. Researchers have looked into immobilizing these enzymes onto carbon nanotubes and nanoparticles to increase sensor sensitivity. In this chapter, we present experimental procedures to perform electrochemical quantification of H2O2, one of the major ROS release from injured cells (macrophages and hepatocytes). PMID:23791096

Enomoto, James; Matharu, Zimple; Revzin, Alexander

2013-01-01

406

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

407

Monitoring the development of a microbial electrolysis cell bioanode using an electrochemical quartz crystal microbalance  

Microsoft Academic Search

In this paper we explored the use of an electrochemical quartz crystal microbalance (QCM) to follow the development of electrochemically active biofilms on electrodes. With this technique it should be possible to monitor simultaneously the increase in biomass and the current generated by the electrogenic bacteria in the biofilm. We monitored the adsorption and the subsequent growth of bacteria that

J. Mieke Kleijn; Quentin Lhuillier; Adriaan W. Jeremiasse

2010-01-01

408

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

409

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

NASA Astrophysics Data System (ADS)

Strontium- and magnesium-doped lanthanum gallate (LSGM) has been considered as a promising electrolyte for solid oxide fuel cell (SOFC) systems in recent years due to its high ionic conductivity and chemical stability over a wide range of oxygen partial pressures and temperatures. This research describes synthesis, physical and mechanical behavior, electrochemical properties, phase evolution, and microstructure of components of an all-perovskite anode-supported intermediate temperature solid oxide fuel cell (ITSOFC), based on porous La 0.75Sr0.25Cr0.5Mn0.5O3 (LSCM) anode, La0.8Sr0.2Ga0.8Mg0.2O 2.8 (LSGM) electrolyte, and porous La0.6Sr0.4Fe 0.8Co0.2O3 (LSCF) cathode. The phase evolution of synthesized LSGM and LSCM powders has been investigated, and it has been confirmed that there is no reaction between LSGM and LSCM at sintering temperature. Using different amounts of poreformers and binders as well as controlling firing temperature, porosity of the anode was optimized while still retaining good mechanical integrity. The effect of cell operation conditions under dry hydrogen fuel on the SOFC open circuit voltage (OCV) and cell performance were also investigated. Characterization study of the synthesized LSGM indicates that sintering at 1500°C obtains higher electrical conductivity compared to the currently published results, while conductivity of pellets sintered at 1400°C and 1450°C would be slightly lower. The effect of sintering temperature on bulk and grain boundary resistivities was also discussed. The mechanical properties, such as hardness, Young's modulus, fracture toughness and modulus of rupture of the electrolyte were determined and correlated with scanning electron microscopy (SEM) morphological characterization. Linear thermal expansion and thermal expansion coefficient of LSGM were also measured.

Mohammadi, Alidad

410

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

NASA Astrophysics Data System (ADS)

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 CeO2-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 1mbar reactant gases H2 and H2O. 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 CeO2-x electrodes undergo Ce3+/Ce4+ oxidation-reduction changes with applied bias. The simultaneous measurements of local surface Ce oxidation states and electric potentials reveal the active ceria regions during H2 electro-oxidation and H2O 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 Ce3+/Ce4+ 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.

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

2010-11-01

411

Domain-like ultra-thin layers deposited electrochemically from carbazole-functionalized perylene bisimides for electron collection in inverted photovoltaic cells.  

PubMed

Domain-like ultra-thin layers deposited electrochemically on an ITO electrode from perylene bisimide derivatives are found to improve the electron collection effectively in inverted photovoltaic cells. PMID:23735975

Feng, Tao; Xiao, Biao; Lv, Ying; Xie, Zengqi; Wu, Hongbin; Ma, Yuguang

2013-07-18

412

Thermal-Fluid and Electrochemical Modeling and Performance Study of a Planar Solid Oxide Electrolysis Cell: Analysis on SOEC Resistances, Size, and Inlet Flow Conditions.  

National Technical Information Service (NTIS)

Argonne National Laboratory and Idaho National Laboratory researchers are analyzing the electrochemical and thermal-fluid behavior of solid oxide electrolysis cells (SOECs) for high temperature steam electrolysis using computational fluid dynamics (CFD) t...

B. Yildiz J. Smith T. Sofu

2006-01-01

413

Technology Base Research Project for electrochemical energy storage  

NASA Astrophysics Data System (ADS)

The US DOE Office of Energy Storage and Distribution provides continuing support for an Energy Storage Program, which includes R and D on advanced electrochemical energy storage and conversion systems. A major goal of this program is to develop electrochemical power sources suitable for application in electric vehicles and/or electric load-leveling devices. The program centers on advanced secondary batteries and fuel cells that offer the potential for high performance and low life-cycle costs. The Technology Base Research Project is divided into three major project elements: Exploratory Research, Applied Science Research, and Air Systems Research. Highlights of each project element are summarized according to the appropriate battery system or electrochemical research area. Cells covered include molten salt, lithium, alkaline, zinc/halogen, alkali/sulfur, nonaqueous, metal/air, fuel cell.

Kinoshita, K.

1987-07-01

414

Tapia's syndrome secondary to laterocervical localization of diffuse large cell lymphoma.  

PubMed

The eponym "Tapia's syndrome" indicates an associated unilateral vocal cord and tongue paralysis secondary to a peripheral involvement of the recurrent laryngeal branch and the hypoglossal nerve. Although mainly observed as a complication of surgery or anaesthesia, it can rarely occur secondary to infectious or neoplastic causes. We are presenting a case of a teen-ager with Tapia's syndrome who had been seeking medical assistance for episodes of loss of consciousness and was diagnosed with a high-grade peripheral B-cell lymphoma, an association not previously described. This syndrome should be remembered even outside the surgical contest for its highly localising value. PMID:23958591

Cantalupo, Gaetano; Spagnoli, Carlotta; Cerasti, Davide; Piccolo, Benedetta; Crisi, Girolamo; Pisani, Francesco

2014-06-01

415

Electrochemical photovoltaic cells CdSe thin film electrodes. Quarterly progress report No. 1, June-August 1979  

Microsoft Academic Search

The overall objective of this program is to obtain AM1 efficiencies in the range of 10% with electrochemical cells utilizing thin film electrodes. The system currently being investigated is the CdSe\\/aqueous sulfide-polysulfide system. This report presents the results to date of the initial CdSe deposition parameter study. The key finding has been that the ratio of Se and Cd in

M. A. Russak; C. Creter

1979-01-01

416

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

Microsoft Academic Search

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

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

2009-01-01

417

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

418

Enhancing the electrochemical properties of LT-LiCoO 2 in lithium cells by doping with Mn  

Microsoft Academic Search

Nearly stoichiometric LiCo1?xMnxO2 mixed oxides (x=0, 0.2) were prepared by using a sol–gel method and their electrochemical properties as lithium cell cathodes were examined. Gels of the two samples fired at 400°C exhibited the same structure as LT-LiCoO2, with the transition elements in a tervalent state as revealed by XPS spectroscopy. A modified spinel structure model is proposed to account

A Caballero; L Hernán; J Morales; E Rodr??guez Castellón; J Santos

2004-01-01

419

Electrochemical production of polysulfides and sodium hydroxide from white liquor: Part II: Electrolysis in a laboratory scale flow cell  

Microsoft Academic Search

Electrochemical production of polysulfide-containing white liquor and pure sodium hydroxide solution was investigated at 90°C in a laboratory scale flow cell. A mixed iridium–tantalum oxide coated titanium electrode was used as the anode and the two electrolyte compartments were separated by a cation-exchange membrane. The process was demonstrated at current densities up to 5kAm-2, resulting in high current efficiencies for

M. BEHM; D. SIMONSSON

1997-01-01

420

Bio-electrochemical treatment of distillery wastewater in microbial fuel cell facilitating decolorization and desalination along with power generation  

Microsoft Academic Search

Microbial fuel cell (MFC; open-air cathode) was evaluated as bio-electrochemical treatment system for distillery wastewater during bioelectricity generation. MFC was operated at three substrate loading conditions in fed-batch mode under acidophilic (pH 6) condition using anaerobic consortia as anodic-biocatalyst. Current visualized marked improvement with increase in substrate load without any process inhibition (2.12–2.48mA). Apart from electricity generation, MFC documented efficient

G. Mohanakrishna; S. Venkata Mohan; P. N. Sarma

2010-01-01

421

Knowledge and attitude of secondary school students in Jos, Nigeria on sickle cell disease  

PubMed Central

Introduction Knowledge about sickle cell disease among youths could constitute an important variable that influences their premarital attitude and behaviour. The study is to determine the knowledge and attitude on Sickle Cell Disease among selected secondary school students in Jos metropolis, Nigeria. Methods A cross sectional descriptive study involving 137 Secondary School Students within Jos metropolis selected by a multistage stratified sampling technique, using self administered structured questionnaire. Data were analyzed using SPSS version 17. Results A total of 137 students were interviewed, Christians 88%, modal age range 15-20 years (72%) and males (51%). Majority (83.2%) of the respondents were aware of SCDs, as an inherited disorder (80.0%), affecting the red blood cells (83.0%) but only half (54%) knew that the disease can only be diagnosed through blood test. Also, only 59% knew their genotype and 11. 1% claimed AS genotype. More than one fourth (25.5%) had wrong belief that SCD is caused by evil spirit while 76% showed wrong attitude involving stigmatization towards individuals with sickle cell disease. Conclusion Comprehensive knowledge about SCD was found to be low despite good awareness among respondents, but only few knew their haemoglobin genotype. If sickle cell disease control strategies must yield any significant results, there is a need to raise awareness about SCD, especially among students in secondary institutions in Nigeria is recommended.

Olakunle, Olarewaju Sunday; Kenneth, Enwerem; Olakekan, Adebimpe Wasiu; Adenike, Olugbenga-Bello

2013-01-01

422

beta-tubulin affects cellulose microfibril orientation in plant secondary fibre cell walls.  

PubMed

Cellulose microfibrils are the major structural component of plant secondary cell walls. Their arrangement in plant primary cell walls, and its consequent influence on cell expansion and cellular morphology, is directed by cortical microtubules; cylindrical protein filaments composed of heterodimers of alpha- and beta-tubulin. In secondary cell walls of woody plant stems the orientation of cellulose microfibrils influences the strength and flexibility of wood, providing the physical support that has been instrumental in vascular plant colonization of the troposphere. Here we show that a Eucalyptus grandisbeta-tubulin gene (EgrTUB1) is involved in determining the orientation of cellulose microfibrils in plant secondary fibre cell walls. This finding is based on RNA expression studies in mature trees, where we identified and isolated EgrTUB1 as a candidate for association with wood-fibre formation, and on the analysis of somatically derived transgenic wood sectors in Eucalyptus. We show that cellulose microfibril angle (MFA) is correlated with EgrTUB1 expression, and that MFA was significantly altered as a consequence of stable transformation with EgrTUB1. Our findings present an important step towards the production of fibres with altered tensile strength, stiffness and elastic properties, and shed light on one of the molecular mechanisms that has enabled trees to dominate terrestrial ecosystems. PMID:17605757

Spokevicius, Antanas V; Southerton, Simon G; MacMillan, Colleen P; Qiu, Deyou; Gan, Siming; Tibbits, Josquin F G; Moran, Gavin F; Bossinger, Gerd

2007-08-01

423

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

424

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

425

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

426

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

427

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

NASA Astrophysics Data System (ADS)

Tin oxide anode materials used in lithium-ion cells experience large volume changes during charging and discharging which cause substantial losses in capacity. In this work, the tin oxide-graphite composite is proposed as an alternative anode material to overcome this problem. The composite was synthesised from a solution of tin chloride dihydrate and graphite powders with citric acid as the chelating agent. In this sol-gel method, a solid phase is formed through a chemical reaction in a liquid phase at moderate temperature. The technique offers several advantages compared to the solid state synthesis technique such as the ability to maintain the homogeneous mixture of precursors during synthesis and to produce small particles. The electrochemical behaviour of the anode material was investigated by means of galvanostatic charge discharge technique. An initial reversible capacity of 748 mAh/g is obtained and nearly 600 mAh/g was retained upon the reaching the fifth cycle. This study shows that the presence of graphite is able to minimise the agglomeration of tin particles that causes large volume changes during cycling, thereby improving cyclability of the anode material.

Hasanaly, Siti Munirah

2010-03-01

428

Bioreactor production of secondary metabolites from cell cultures of periwinkle and sandalwood.  

PubMed

A bench-top bioreactor allowing continuous extraction of secondary metabolites is designed for Catharanthus roseus L. (G.) Don (periwinkle) and Santalum album L. (sandalwood) plant cell suspensions. Periwinkle cell cultures are exposed to biotic elicitors (Aspergillus niger, crude chitin) and abiotic elicitors (mannitol, methyl jasmonate) to induce alkaloid production. Whereas most of the biotic elicitors are effective when added on day 15 of culture, the abiotic elicitors are effective when added on day 20. The use of trans-cinnamic acid, an inhibitor of phenylalanine ammonia lyase (PAL) activity, results in significant increase in the alkaloid production of periwinkle cell cultures. Exposure of the cells to mannitol-induced osmotic stress produced marked increment in the total alkaloid production. When biotic and abiotic stress treatments are applied sequentially, an additive effect in alkaloid accumulation is observed. Although no essential oils are detected, secondary metabolites in the form of phenolics are produced by the sandalwood cell cultures in the bioreactor environment. The use of morphologic modification such as organ cultures and transformed cultures is believed to be required for both production and storage of essential oil constituents in sandalwood. The present chapter demonstrates that periwinkle and sandalwood cell suspensions could be developed and successfully cultured in a modified air-lift bioreactor. The exploitation of variant cell strains and biotransformation of added precursors can certainly improve the use of periwinkle and sandalwood cell cultures for the bioproduction of desired compounds. PMID:19521856

Valluri, Jagan V

2009-01-01

429

Thermodynamic and kinetic study of mixed metal oxide cathode material for lithium organic polymer electrolyte electrochemical cells  

NASA Astrophysics Data System (ADS)

The thermodynamics and discharge kinetics of the lithium/bismuth modified manganese dioxide electrochemical couple was investigated. These investigations coupled with biased impedance spectroscopy studies lead to the establishment of a model of the electrochemical interfaces of the system. Biased impedance spectroscopy allows for the study of the electrodes during open circuit and discharge conditions. This ability to study the electrode interface during discharge allowed for the development of an equivalent circuit and description of the complex interface of the mixed metal oxide. The results of these techniques were the establishment of a theory of the discharge mechanism of the lithium/bismuth modified manganese dioxide electrochemical cell and the processes involved. Equivalent circuit analysis of materials provides data for comparison. Equivalent circuit analysis when used with biased impedance spectroscopy provides valued component data for lithium battery cathode material. The model, therefore, provides an invaluable tool in the investigation of new materials for use as lithium battery cathodes. Kinetic measurements were used to determine the catalytic nature of the bismuth phase in bismuth modified manganese dioxide lithium primary battery cathode material. A reduction in activation energy for lithium cells was identified in the bismuth manganese mixed metal oxide as compared to manganese dioxide. Impedance spectroscopy allowed for the identification of an additional process linked to the catalytic behavior of the bismuth oxide phase of the bismuth manganese mixed metal oxide. An additional part of the studies focused on the thermodynamics and kinetics of the lithium polymer electrolyte cells with bismuth manganese mixed metal oxide cathodes. This study resulted in the determination of thermodynamic properties of the electrochemical couple. Discharge kinetic measurements lead to the establishment of optimum cathode formulations. This optimization considered both gravimetric and volumetric efficiencies. Measurements examined the relationship between discharge characteristics and cathode material concentration and cathode thickness.

Atwater, Terrill Bradford

1997-09-01

430

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.

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

2011-01-01

431

Electrochemical thermodynamic measurement system  

DOEpatents

The present invention provides systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and electrochemical energy storage and conversion systems. Systems and methods of the present invention are configured for simultaneously collecting a suite of measurements characterizing a plurality of interconnected electrochemical and thermodynamic parameters relating to the electrode reaction state of advancement, voltage and temperature. Enhanced sensitivity provided by the present methods and systems combined with measurement conditions that reflect thermodynamically stabilized electrode conditions allow very accurate measurement of thermodynamic parameters, including state functions such as the Gibbs free energy, enthalpy and entropy of electrode/electrochemical cell reactions, that enable prediction of important performance attributes of electrode materials and electrochemical systems, such as the energy, power density, current rate and the cycle life of an electrochemical cell.

Reynier, Yvan (Meylan, FR) [Meylan, FR; Yazami, Rachid (Los Angeles, CA) [Los Angeles, CA; Fultz, Brent T. (Pasadena, CA) [Pasadena, CA

2009-09-29

432

Electrochemical Characteristics of Acid Electrolytes for Fuel Cells. Annual Report January 1, 1989-December 31, 1989.  

National Technical Information Service (NTIS)

Five topics investigated by the Gas Research Institute (GRI) contractors at Case Western Reserve University (CWRU) during the past year included: (1) electrochemical evaluation of perfluorinated electrolyte, (2) the Nafion solid polymer electrolyte (SPE) ...

R. Adzic D. Gervasio K. Kanamura A. Razaq M. Razaq

1990-01-01

433

Interface-Mediated Electrochemical Effects in Lithium/Polymer-Ceramic Cells (POSTPRINT).  

National Technical Information Service (NTIS)

This paper presents and discusses a method to achieve beneficial electrochemical effects mediated by interfaces in an ionic conducting polymer matrix. The beneficial effects include enhanced ionic transport, catalysis of anodic oxidation reaction, and sta...

B. Kumar J. Kumar S. J. Rodrigues

2001-01-01

434

Direct numerical simulation of transport and electrochemical reaction in battery and fuel cell electrodes  

NASA Astrophysics Data System (ADS)

Batteries and fuel cells are widely used to generate electrical energy, especially in recent applications to electric and hybrid vehicles. To simulate a porous electrode for batteries and fuel cells, macro-homogeneous models are often employed in which the actual morphology of the electrode is ignored, thereby making computations much easier. However, such models are based on the volume-averaging technique, which smears the microscopically complex interfacial structures and has to invoke empirical correlations for describing the effective transport properties in a multiphase system. In this work, a methodology is developed to achieve the description on the pore level based on direct numerical simulation (DNS) method. The DNS solves the accurate point-wise conservation equations on a real micro-structure of the porous electrode and hence utilizes the intrinsic transport properties for each phase. To demonstrate the DNS method, an idealized morphology and further a random microstructure are constructed to represent all the phases composing the porous electrode. A single set of conservation equations of charge and species valid in all phases are developed and numerically solved using a finite volume technique. The present DNS model is first applied to simulate the behavior of an intercalative carbon electrode in the widely used lithium-ion cell. The concentration and potential distributions in both solid and electrolyte phases at the pore level are obtained across the electrode during the discharge. The species and charge transport processes, as well as the electrochemical reactions, are computationally visualized when discharging the electrode. In addition, empirical correlations in porous electrode theory, which describe the dependency of effective properties (diffusion coefficient, conductivity, etc.) on the porosity, are corroborated using the fundamental DNS data. Then the discharge processes of a full lithium ion cell at various rates are simulated with DNS approach and verified by the experimental data. In the application to the cathode catalyst layer of PEM fuel cells, DNS is employed to identify three characteristic voltage losses: kinetics losses, ohmic losses and O2 transport losses. On a constructed random microstructure, DNS is also utilized to optimize the inlet air humidity and the composition design and hence achieve the minimum voltage loss during operation. In summary, the newly developed DNS method has provided an effective method to simulate behavior of thin porous electrodes with microscopically complicated geometries and the fundamentals insight into structure-performance relationships of porous electrodes for the first time.

Wang, Guoqing

435

Effect of secondary radiation produced by 70 GeV protons on DNA of mammalian cells.  

PubMed

It is shown that the RBE of the 70 GeV proton secondary radiation for the induction of single-strand break is 1.6-7.6 in Chinese hamster fibroblasts and 1.04-3.8 in limphoid cells and for the lethality of Chinese hamster cells 1.14-1.7. The RBE value increases with decreasing dose of the secondary radiation. On post-irradiation incubation of mammalian cells at 37 degrees C, single-strand breaks induced by the secondary radiation are repaired with the sane time course as those induced by gamma-rays. In our earlier works we have made an attempt to estimate the biological efficiency of radiation generated by the 70 GeV protons on bacteria, phage T4 and Vicia faba beans. The obtained values of the relative biological efficiency (RBE) of this radiation varied between 1.4 and 5.5, depending on the object, criterion of estimation, times of registration and other experimental conditions. The aim of the present work is to estimate the biological efficiency of synchrotron radiation by its effect on mammalian cells. PMID:11539632

Leont'eva, G A; Fomenko, B S; Antipov, A V

1984-01-01

436

Enhancement of the electrochemical membrane electrode assembly in proton exchange membrane fuel cells through direct microwave treatment  

NASA Astrophysics Data System (ADS)

Demonstrated herein is a novel and easily controllable method using direct microwave irradiation treatment to enhance the