Coalbed methane and tight gas no longer unconventional resources

International Nuclear Information System (INIS)

Gatens, M.

2006-01-01

Unconventional gas refers to natural gas contained in difficult-to-produce formations that require special drilling and completion techniques to achieve commercial production. It includes tight gas, coal seams, organic shales, and gas hydrates. Canada's vast unconventional gas resource is becoming an increasingly important part of the country's gas supply. The emergence of unconventional gas production in Canada over the past several years has made the unconventional increasingly conventional in terms of industry activity. It was suggested that in order to realize the potential for unconventional gas in Canada, all stakeholders should engage to ensure the development is environmentally responsible. Unconventional gas accounts for nearly one third of U.S. gas production. It also accounts for nearly 5 Bcf per day and growing. The impetus to this sudden growth has been the gradual and increasing contribution of tight sands and limes to Canadian production, which accounts for more than 4 Bcf per day. Coalbed methane (CBM) is at 0.5 Bcf per day and growing. In response to expectations that CBM will reach 2 to 3 Bcf per day over the next 2 decades, Canadian producers are placing more emphasis on unconventional resource plays, including organic shales and gas hydrates. As such, significant growth of unconventional gas is anticipated. This growth will be facilitated by the adoption of U.S..-developed technologies and new Canadian technologies. It was suggested that research and development will be key to unlocking the unconventional gas potential. It was also suggested that the already existing, strong regulatory structure should continue in order to accommodate this growth in a sustainable manner. figs

Feasibility study on application of volume acid fracturing technology to tight gas carbonate reservoir development

Directory of Open Access Journals (Sweden)

Nianyin Li

2015-09-01

Full Text Available How to effectively develop tight-gas carbonate reservoir and achieve high recovery is always a problem for the oil and gas industry. To solve this problem, domestic petroleum engineers use the combination of the successful experiences of North American shale gas pools development by stimulated reservoir volume (SRV fracturing with the research achievements of Chinese tight gas development by acid fracturing to propose volume acid fracturing technology for fractured tight-gas carbonate reservoir, which has achieved a good stimulation effect in the pilot tests. To determine what reservoir conditions are suitable to carry out volume acid fracturing, this paper firstly introduces volume acid fracturing technology by giving the stimulation mechanism and technical ideas, and initially analyzes the feasibility by the comparison of reservoir characteristics of shale gas with tight-gas carbonate. Then, this paper analyzes the validity and limitation of the volume acid fracturing technology via the analyses of control conditions for volume acid fracturing in reservoir fracturing performance, natural fracture, horizontal principal stress difference, orientation of in-situ stress and natural fracture, and gives the solution for the limitation. The study results show that the volume acid fracturing process can be used to greatly improve the flow environment of tight-gas carbonate reservoir and increase production; the incremental or stimulation response is closely related with reservoir fracturing performance, the degree of development of natural fracture, the small intersection angle between hydraulic fracture and natural fracture, the large horizontal principal stress difference is easy to form a narrow fracture zone, and it is disadvantageous to create fracture network, but the degradable fiber diversion technology may largely weaken the disadvantage. The practices indicate that the application of volume acid fracturing process to the tight-gas carbonate

Naturally fractured tight gas reservoir detection optimization

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-06-01

Building upon the partitioning of the Greater Green River Basin (GGRB) that was conducted last quarter, the goal of the work this quarter has been to conclude evaluation of the Stratos well and the prototypical Green River Deep partition, and perform the fill resource evaluation of the Upper Cretaceous tight gas play, with the goal of defining target areas of enhanced natural fracturing. The work plan for the quarter of November 1-December 31, 1998 comprised four tasks: (1) Evaluation of the Green River Deep partition and the Stratos well and examination of potential opportunity for expanding the use of E and P technology to low permeability, naturally fractured gas reservoirs, (2) Gas field studies, and (3) Resource analysis of the balance of the partitions.

The RealGas and RealGasH2O options of the TOUGH+ code for the simulation of coupled fluid and heat flow in tight/shale gas systems

Science.gov (United States)

We developed two new EOS additions to the TOUGH+ family of codes, the RealGasH2O and RealGas. The RealGasH2O EOS option describes the non-isothermal two-phase flow of water and a real gas mixture in gas reservoirs, with a particular focus in ultra-tight (such as tight-sand and sh...

Pore-scale mechanisms of gas flow in tight sand reservoirs

Energy Technology Data Exchange (ETDEWEB)

Silin, D.; Kneafsey, T.J.; Ajo-Franklin, J.B.; Nico, P.

2010-11-30

Tight gas sands are unconventional hydrocarbon energy resource storing large volume of natural gas. Microscopy and 3D imaging of reservoir samples at different scales and resolutions provide insights into the coaredo not significantly smaller in size than conventional sandstones, the extremely dense grain packing makes the pore space tortuous, and the porosity is small. In some cases the inter-granular void space is presented by micron-scale slits, whose geometry requires imaging at submicron resolutions. Maximal Inscribed Spheres computations simulate different scenarios of capillary-equilibrium two-phase fluid displacement. For tight sands, the simulations predict an unusually low wetting fluid saturation threshold, at which the non-wetting phase becomes disconnected. Flow simulations in combination with Maximal Inscribed Spheres computations evaluate relative permeability curves. The computations show that at the threshold saturation, when the nonwetting fluid becomes disconnected, the flow of both fluids is practically blocked. The nonwetting phase is immobile due to the disconnectedness, while the permeability to the wetting phase remains essentially equal to zero due to the pore space geometry. This observation explains the Permeability Jail, which was defined earlier by others. The gas is trapped by capillarity, and the brine is immobile due to the dynamic effects. At the same time, in drainage, simulations predict that the mobility of at least one of the fluids is greater than zero at all saturations. A pore-scale model of gas condensate dropout predicts the rate to be proportional to the scalar product of the fluid velocity and pressure gradient. The narrowest constriction in the flow path is subject to the highest rate of condensation. The pore-scale model naturally upscales to the Panfilov's Darcy-scale model, which implies that the condensate dropout rate is proportional to the pressure gradient squared. Pressure gradient is the greatest near the

Electrochemical corrosion behavior of gas atomized Al–Ni alloy powders

International Nuclear Information System (INIS)

Osório, Wislei R.; Spinelli, José E.; Afonso, Conrado R.M.; Peixoto, Leandro C.; Garcia, Amauri

2012-01-01

Highlights: ► Spray-formed Al–Ni alloy powders have cellular microstructures. ► Porosity has no deleterious effect on the electrochemical corrosion behavior. ► Better pitting corrosion resistance is related to a fine powder microstructure. ► A coarse microstructure can be related to better general corrosion resistance. - Abstract: This is a study describing the effects of microstructure features of spray-formed Al–Ni alloy powders on the electrochemical corrosion resistance. Two different spray-formed powders were produced using nitrogen (N 2 ) gas flow (4 and 8 bar were used). Electrochemical impedance spectroscopy (EIS), potentiodynamic anodic polarization techniques and an equivalent circuit analysis were used to evaluate the electrochemical behavior in a dilute 0.05 M NaCl solution at room temperature. It was found that a N 2 gas pressure of 8 bar resulted in a microstructure characterized by a high fraction of small powders and fine cell spacings, having improved pitting potential but higher corrosion current density when compared with the corresponding results of a coarser microstructure array obtained under a lower pressure. A favorable effect in terms of current density and oxide protective film formation was shown to be associated with the coarser microstructure, however, its pitting potential was found to be lower than that of the finer microstructure.

Thermophysical instruments for non-destructive examination of tightness and internal gas pressure or irradiated power reactor fuel rods

International Nuclear Information System (INIS)

Pastoushin, V.V.; Novikov, A.Yu.; Bibilashvili, Yu.K.

1998-01-01

The developed thermophysical method and technical instruments for non-destructive leak-tightness and gas pressure inspection inside irradiated power reactor fuel rods and FAs under poolside and hot cell conditions are described. The method of gas pressure measuring based on the examination of parameters of thermal convection that aroused in gas volume of rod plenum by special technical instruments. The developed method and technique allows accurate value determination of not only one of the main critical rod parameters, namely total internal gas pressure, that forms rod mean life in the reactor core, but also the partial pressure of every main constituent of gaseous mixture inside irradiated fuel rod, that provides the feasibility of authentic and reliable leak-tightness detection. The described techniques were experimentally checked during the examination of all types power reactor fuel rods existing in Russia (WWER, BN, RBMK) and could form the basis for new technique development for non-destructive examination of PWR (and other) type rods and FAs having gas plenum filled with spring or another elements of design. (author)

Prediction of Gas Leak Tightness of Superplastically Formed Products

NARCIS (Netherlands)

Snippe, Q.H.C.; Meinders, Vincent T.; Barlat, F; Moon, Y.H.; Lee, M.G.

2010-01-01

In some applications, in this case an aluminium box in a subatomic particle detector containing highly sensitive detecting devices, it is important that a formed sheet should show no gas leak from one side to the other. In order to prevent a trial-and-error procedure to make this leak tight box, a

Review—Physicochemical hydrodynamics of gas bubbles in two phase electrochemical systems

Science.gov (United States)

Taqieddin, Amir; Nazari, Roya; Rajic, Ljiljana; Alshawabkeh, Akram

2018-01-01

Electrochemical systems suffer from poor management of evolving gas bubbles. Improved understanding of bubbles behavior helps to reduce overpotential, save energy and enhance the mass transfer during chemical reactions. This work investigates and reviews the gas bubbles hydrodynamics, behavior, and management in electrochemical cells. Although the rate of bubble growth over the electrode surface is well understood, there is no reliable prediction of bubbles break-off diameter from the electrode surface because of the complexity of bubbles motion near the electrode surface. Particle Image Velocimetry (PIV) and Laser Doppler Anemometry (LDA) are the most common experimental techniques to measure bubble dynamics. Although the PIV is faster than LDA, both techniques are considered expensive and time-consuming. This encourages adapting Computational Fluid Dynamics (CFD) methods as an alternative to study bubbles behavior. However, further development of CFD methods is required to include coalescence and break-up of bubbles for better understanding and accuracy. The disadvantages of CFD methods can be overcome by using hybrid methods. The behavior of bubbles in electrochemical systems is still a complex challenging topic which requires a better understanding of the gas bubbles hydrodynamics and their interactions with the electrode surface and bulk liquid, as well as between the bubbles itself.

Co-extrusion of electrolyte/anode functional layer/anode triple-layer ceramic hollow fibres for micro-tubular solid oxide fuel cells-electrochemical performance study

Science.gov (United States)

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

2015-01-01

In this study, the effects of an anode functional layer (AFL) with controlled thickness on physical and electrochemical properties of a micro-tubular SOFC have been systematically studied. A series of electrolyte/AFL/anode triple-layer hollow fibres with controllable AFL thicknesses (16.9-52.7 μm) have been fabricated via a single-step phase-inversion assisted co-extrusion technique. Both robustness of the cell and gas-tightness of the electrolyte layer are considerably improved by introducing the AFL of this type. The fracture force of the sample with the thickest AFL (9.67 N) almost doubles when compared to the electrolyte/anode dual-layer counterpart (5.24 N). Gas-tightness of the electrolyte layer is also considerably increased as AFL contributes to better-matched sintering behaviours between different components. Moreover, the formation of an AFL simultaneously with electrolyte and anode significantly improves the cell performances. The sample with the thinnest AFL (approximately 16.9 μm, 6% of the total anode thickness) leads to a 30% (from 0.89 to 1.21 W cm-2) increase in maximum power density, due to increased triple-phase boundaries (TPB). However, further increase in TPB from a thicker AFL is less effective for improving the cell performance, due to the substantially increased fuel diffusion resistance and subsequently higher concentration polarization. This indicates that the control over the AFL thickness is critically important in avoiding offsetting the benefits of extended TPB and consequently decreased cell performances.

Pore Structure and Limit Pressure of Gas Slippage Effect in Tight Sandstone

Science.gov (United States)

You, Lijun; Xue, Kunlin; Kang, Yili; Liao, Yi

2013-01-01

Gas slip effect is an important mechanism that the gas flow is different from liquid flow in porous media. It is generally considered that the lower the permeability in porous media is, the more severe slip effect of gas flow will be. We design and then carry out experiments with the increase of backpressure at the outlet of the core samples based on the definition of gas slip effect and in view of different levels of permeability of tight sandstone reservoir. This study inspects a limit pressure of the gas slip effect in tight sandstones and analyzes the characteristic parameter of capillary pressure curves. The experimental results indicate that gas slip effect can be eliminated when the backpressure reaches a limit pressure. When the backpressure exceeds the limit pressure, the measured gas permeability is a relatively stable value whose range is less than 3% for a given core sample. It is also found that the limit pressure increases with the decreasing in permeability and has close relation with pore structure of the core samples. The results have an important influence on correlation study on gas flow in porous medium, and are beneficial to reduce the workload of laboratory experiment. PMID:24379747

ELECTROCHEMICAL SEPARATION AND CONCENTRATION OF HYDROGEN SULFIDE FROM GAS MIXTURES

Science.gov (United States)

Winnick, Jack; Sather, Norman F.; Huang, Hann S.

1984-10-30

A method of removing sulfur oxides of H.sub.2 S from high temperature gas mixtures (150.degree.-1000.degree. C.) is the subject of the present invention. An electrochemical cell is employed. The cell is provided with inert electrodes and an electrolyte which will provide anions compatible with the sulfur containing anions formed at the anode. The electrolyte is also selected to provide inert stable cations at the temperatures encountered. The gas mixture is passed by the cathode where the sulfur gases are converted to SO.sub.4 -- or, in the case of H.sub.2 S, to S--. The anions migrate to the anode where they are converted to a stable gaseous form at much greater concentration levels (>10X). Current flow may be effected by utilizing an external source of electrical energy or by passing a reducing gas such as hydrogen past the anode.

Shale Gas and Tight Oil: A Panacea for the Energy Woes of America?

Science.gov (United States)

Hughes, J. D.

2012-12-01

Shale gas has been heralded as a "game changer" in the struggle to meet America's demand for energy. The "Pickens Plan" of Texas oil and gas pioneer T.Boone Pickens suggests that gas can replace coal for much of U.S. electricity generation, and oil for, at least, truck transportation1. Industry lobby groups such as ANGA declare "that the dream of clean, abundant, home grown energy is now reality"2. In Canada, politicians in British Columbia are racing to export the virtual bounty of shale gas via LNG to Asia (despite the fact that Canadian gas production is down 16 percent from its 2001 peak). And the EIA has forecast that the U.S. will become a net exporter of gas by 20213. Similarly, recent reports from Citigroup and Harvard suggest that an oil glut is on the horizon thanks in part to the application of fracking technology to formerly inaccessible low permeability tight oil plays. The fundamentals of well costs and declines belie this optimism. Shale gas is expensive gas. In the early days it was declared that "continuous plays" like shale gas were "manufacturing operations", and that geology didn't matter. One could drill a well anywhere, it was suggested, and expect consistent production. Unfortunately, Mother Nature always has the last word, and inevitably the vast expanses of purported potential shale gas resources contracted to "core" areas, where geological conditions were optimal. The cost to produce shale gas ranges from 4.00 per thousand cubic feet (mcf) to 10.00, depending on the play. Natural gas production is a story about declines which now amount to 32% per year in the U.S. So 22 billion cubic feet per day of production now has to be replaced each year to keep overall production flat. At current prices of 2.50/mcf, industry is short about 50 billion per year in cash flow to make this happen4. As a result I expect falling production and rising prices in the near to medium term. Similarly, tight oil plays in North Dakota and Texas have been heralded

Electrochemical performance of solid oxide fuel cells having electrolytes made by suspension and solution precursor plasma spraying

Science.gov (United States)

Marr, M.; Kuhn, J.; Metcalfe, C.; Harris, J.; Kesler, O.

2014-01-01

Yttria-stabilized zirconia (YSZ) electrolytes were deposited by suspension plasma spraying (SPS) and solution precursor plasma spraying (SPPS). The electrolytes were evaluated for permeability, microstructure, and electrochemical performance. With SPS, three different suspensions were tested to explore the influence of powder size distribution and liquid properties. Electrolytes made from suspensions of a powder with d50 = 2.6 μm were more gas-tight than those made from suspensions of a powder with d50 = 0.6 μm. A peak open circuit voltage of 1.00 V was measured at 750 °C with a cell with an electrolyte made from a suspension of d50 = 2.6 μm powder. The use of a flammable suspension liquid was beneficial for improving electrolyte conductivity when using lower energy plasmas, but the choice of liquid was less important when using higher energy plasmas. With SPPS, peak electrolyte conductivities were comparable to the peak conductivities of the SPS electrolytes. However, leak rates through the SPPS electrolytes were higher than those through the electrolytes made from suspensions of d50 = 2.6 μm powder. The electrochemical test data on SPPS electrolytes are the first reported in the literature.

Naturally fractured tight gas reservoir detection optimization

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-04-30

In March, work continued on characterizing probabilities for determining natural fracturing associated with the GGRB for the Upper Cretaceous tight gas plays. Structural complexity, based on potential field data and remote sensing data was completed. A resource estimate for the Frontier and Mesa Verde play was also completed. Further, work was also conducted to determine threshold economics for the play based on limited current production in the plays in the Wamsutter Ridge area. These analyses culminated in a presentation at FETC on 24 March 1999 where quantified natural fracture domains, mapped on a partition basis, which establish ''sweet spot'' probability for natural fracturing, were reviewed. That presentation is reproduced here as Appendix 1. The work plan for the quarter of January 1, 1999--March 31, 1999 comprised five tasks: (1) Evaluation of the GGRB partitions for structural complexity that can be associated with natural fractures, (2) Continued resource analysis of the balance of the partitions to determine areas with higher relative gas richness, (3) Gas field studies, (4) Threshold resource economics to determine which partitions would be the most prospective, and (5) Examination of the area around the Table Rock 4H well.

Tight gas sand tax credit yields opportunities

International Nuclear Information System (INIS)

Lewis, F.W.; Osburn, A.S.

1991-01-01

The U.S. Internal Revenue Service on Apr. 1, 1991, released the inflation adjustments used in the calculations of Non-Conventional Fuel Tax Credits for 1990. The inflation adjustment, 1.6730, when applied to the base price of $3/bbl of oil equivalent, adjusts the tax credit to $5.019/bbl for oil and 86.53 cents/MMBTU for gas. The conversion factor for equivalent fuels is 5.8 MMBTU/bbl. Unfortunately, the tax credit for tight formation gas continues to be unadjusted for inflation and remains 52 cents/MMBTU. As many producers are aware, the Omnibus Budget Reconciliation Act of 1990 expanded the dates of eligibility and the usage for-Non-Conventional Fuel Tax Credits. Among other provisions, eligible wells may be placed in service until Jan. 1, 1992, and once in place may utilize the credit for production through Dec. 31, 2002. Both dates are 2 year extensions from previous regulations

Risks and mitigation options for on-site storage of wastewater from shale gas and tight oil development

International Nuclear Information System (INIS)

Kuwayama, Yusuke; Roeshot, Skyler; Krupnick, Alan; Richardson, Nathan; Mares, Jan

2017-01-01

We provide a critical review of existing research and information regarding the sources of risk associated with on-site shale gas and tight oil wastewater storage in the United States, the gaps that exist in knowledge regarding these risks, policy and technology options for addressing the risks, and the relative merits of those options. Specifically, we (a) identify the potential risks to human and ecological health associated with on-site storage of shale gas and tight oil wastewater via a literature survey and analysis of data on wastewater spills and regulatory violations, (b) provide a detailed description of government regulations or industry actions that may mitigate these risks to human and ecological health, and (c) provide a critical review of this information to help generate progress toward concrete action to make shale gas and tight oil development more sustainable and more acceptable to a skeptical public, while keeping costs down. - Highlights: • We review current research/information on shale gas and tight oil wastewater storage. • Pit overflows, tank overfills, and liner malfunctions are common spill causes. • Tanks lead to smaller and less frequent spills than pits, but are not a magic bullet. • State regulations for on-site oil and gas wastewater storage are very heterogeneous.

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

Science.gov (United States)

Balachandran, Uthamalingam; Poeppel, Roger B.; Kleefisch, Mark S.; Kobylinski, Thaddeus P.; Udovich, Carl A.

1994-01-01

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.

Electrochemical Cell

DEFF Research Database (Denmark)

1999-01-01

The invention relates to a rechargeable electrochemical cell comprising a negative electrode, an electrolyte and a positive electrode in which the positive electrode structure comprises a lithium cobalt manganese oxide of the composition Li¿2?Co¿y?Mn¿2-y?O¿4? where 0 ... for capacity losses in lithium ion cells and lithium-alloy cells....

Bussing Structure In An Electrochemical Cell

Science.gov (United States)

Romero, Antonio L.

2001-06-12

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

New Method for Super Hydrophobic Treatment of Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells Using Electrochemical Reduction of Diazonium Salts.

Science.gov (United States)

Thomas, Yohann R J; Benayad, Anass; Schroder, Maxime; Morin, Arnaud; Pauchet, Joël

2015-07-15

The purpose of this article is to report a new method for the surface functionalization of commercially available gas diffusion layers (GDLs) by the electrochemical reduction of diazonium salt containing hydrophobic functional groups. The method results in superhydrophobic GDLs, over a large area, without pore blocking. An X-ray photoelectron spectroscopy study based on core level spectra and chemical mapping has demonstrated the successful grafting route, resulting in a homogeneous distribution of the covalently bonded hydrophobic molecules on the surface of the GDL fibers. The result was corroborated by contact angle measurement, showing similar hydrophobicity between the grafted and PTFE-modified GDLs. The electrochemically modified GDLs were tested in proton exchange membrane fuel cells under automotive, wet, and dry conditions and demonstrated improved performance over traditional GDLs.

Study of the sealing performance of tubing adapters in gas-tight deep-sea water sampler

Directory of Open Access Journals (Sweden)

Huang Haocai

2014-09-01

Full Text Available Tubing adapter is a key connection device in Gas-Tight Deep-Sea Water Sampler (GTWS. The sealing performance of the tubing adapter directly affects the GTWS’s overall gas tightness. Tubing adapters with good sealing performance can ensure the transmission of seawater samples without gas leakage and can be repeatedly used. However, the sealing performance of tubing adapters made of different materials was not studied sufficiently. With the research discussed in this paper, the materials match schemes of the tubing adapters were proposed. With non-linear finite element contact analysis and sea trials in the South China Sea, it is expected that the recommended materials match schemes not only meet the requirements of tubing adapters' sealing performance but also provide the feasible options for the following research on tubing adapters in GTWS

Study of the sealing performance of tubing adapters in gas-tight deep-sea water sampler

Directory of Open Access Journals (Sweden)

Haocai Huang

2014-09-01

Full Text Available Tubing adapter is a key connection device in Gas-Tight Deep-Sea Water Sampler (GTWS. The sealing performance of the tubing adapter directly affects the GTWS's overall gas tightness. Tubing adapters with good sealing performance can ensure the transmission of seawater samples without gas leakage and can be repeatedly used. However, the sealing performance of tubing adapters made of different materials was not studied sufficiently. With the research discussed in this paper, the materials match schemes of the tubing adapters were proposed. With non-linear finite element contact analysis and sea trials in the South China Sea, it is expected that the recommended materials match schemes not only meet the requirements of tubing adapters’ sealing performance but also provide the feasible options for the following research on tubing adapters in GTWS.

Preliminary Electrochemical Characterization of Anode Supported Solid Oxide Cell (AS-SOC) Produced in the Institute of Power Engineering Operated in Electrolysis Mode (SOEC)

Science.gov (United States)

Kupecki, Jakub; Motyliński, Konrad; Skrzypkiewicz, Marek; Wierzbicki, Michał; Naumovich, Yevgeniy

2017-12-01

The article discusses the operation of solid oxide electrochemical cells (SOC) developed in the Institute of Power Engineering as prospective key components of power-to-gas systems. The fundamentals of the solid oxide cells operated as fuel cells (SOFC - solid oxide fuel cells) and electrolysers (SOEC - solid oxide fuel cells) are given. The experimental technique used for electrochemical characterization of cells is presented. The results obtained for planar cell with anodic support are given and discussed. Based on the results, the applicability of the cells in power-to-gas systems (P2G) is evaluated.

Detailed dynamic solid oxide fuel cell modeling for electrochemical impedance spectra simulation

Energy Technology Data Exchange (ETDEWEB)

Hofmann, Ph. [Laboratory of Steam Boilers and Thermal Plants, School of Mechanical Engineering, Thermal Engineering Section, National Technical University of Athens, Heroon Polytechniou 9, 15780 Athens (Greece); Panopoulos, K.D. [Institute for Solid Fuels Technology and Applications, Centre for Research and Technology Hellas, 4th km. Ptolemais-Mpodosakeio Hospital, Region of Kouri, P.O. Box 95, GR 502, 50200 Ptolemais (Greece)

2010-08-15

This paper presents a detailed flexible mathematical model for planar solid oxide fuel cells (SOFCs), which allows the simulation of steady-state performance characteristics, i.e. voltage-current density (V-j) curves, and dynamic operation behavior, with a special capability of simulating electrochemical impedance spectroscopy (EIS). The model is based on physico-chemical governing equations coupled with a detailed multi-component gas diffusion mechanism (Dusty-Gas Model (DGM)) and a multi-step heterogeneous reaction mechanism implicitly accounting for the water-gas-shift (WGS), methane reforming and Boudouard reactions. Spatial discretization can be applied for 1D (button-cell approximation) up to quasi-3D (full size anode supported cell in cross-flow configuration) geometries and is resolved with the finite difference method (FDM). The model is built and implemented on the commercially available modeling and simulations platform gPROMS trademark. Different fuels based on hydrogen, methane and syngas with inert diluents are run. The model is applied to demonstrate a detailed analysis of the SOFC inherent losses and their attribution to the EIS. This is achieved by means of a step-by-step analysis of the involved transient processes such as gas conversion in the main gas chambers/channels, gas diffusion through the porous electrodes together with the heterogeneous reactions on the nickel catalyst, and the double-layer current within the electrochemical reaction zone. The model is an important tool for analyzing SOFC performance fundamentals as well as for design and optimization of materials' and operational parameters. (author)

ADVANCED FRACTURING TECHNOLOGY FOR TIGHT GAS: AN EAST TEXAS FIELD DEMONSTRATION

Energy Technology Data Exchange (ETDEWEB)

Mukul M. Sharma

2005-03-01

The primary objective of this research was to improve completion and fracturing practices in gas reservoirs in marginal plays in the continental United States. The Bossier Play in East Texas, a very active tight gas play, was chosen as the site to develop and test the new strategies for completion and fracturing. Figure 1 provides a general location map for the Dowdy Ranch Field, where the wells involved in this study are located. The Bossier and other tight gas formations in the continental Unites States are marginal plays in that they become uneconomical at gas prices below $2.00 MCF. It was, therefore, imperative that completion and fracturing practices be optimized so that these gas wells remain economically attractive. The economic viability of this play is strongly dependent on the cost and effectiveness of the hydraulic fracturing used in its well completions. Water-fracs consisting of proppant pumped with un-gelled fluid is the type of stimulation used in many low permeability reservoirs in East Texas and throughout the United States. The use of low viscosity Newtonian fluids allows the creation of long narrow fractures in the reservoir, without the excessive height growth that is often seen with cross-linked fluids. These low viscosity fluids have poor proppant transport properties. Pressure transient tests run on several wells that have been water-fractured indicate a long effective fracture length with very low fracture conductivity even when large amounts of proppant are placed in the formation. A modification to the water-frac stimulation design was needed to transport proppant farther out into the fracture. This requires suspending the proppant until the fracture closes without generating excessive fracture height. A review of fracture diagnostic data collected from various wells in different areas (for conventional gel and water-fracs) suggests that effective propped lengths for the fracture treatments are sometimes significantly shorter than those

Genetic Types and Source of the Upper Paleozoic Tight Gas in the Hangjinqi Area, Northern Ordos Basin, China

Directory of Open Access Journals (Sweden)

Xiaoqi Wu

2017-01-01

Full Text Available The molecular and stable isotopic compositions of the Upper Paleozoic tight gas in the Hangjinqi area in northern Ordos Basin were investigated to study the geochemical characteristics. The tight gas is mainly wet with the dryness coefficient (C1/C1–5 of 0.853–0.951, and δ13C1 and δ2H-C1 values are ranging from -36.2‰ to -32.0‰ and from -199‰ to -174‰, respectively, with generally positive carbon and hydrogen isotopic series. Identification of gas origin indicates that tight gas is mainly coal-type gas, and it has been affected by mixing of oil-type gas in the wells from the Shilijiahan and Gongkahan zones adjacent to the Wulanjilinmiao and Borjianghaizi faults. Gas-source correlation indicates that coal-type gas in the Shiguhao zone displays distal-source accumulation. It was mainly derived from the coal-measure source rocks in the Upper Carboniferous Taiyuan Formation (C3t and Lower Permian Shanxi Formation (P1s, probably with a minor contribution from P1s coal measures from in situ Shiguhao zone. Natural gas in the Shilijiahan and Gongkahan zones mainly displays near-source accumulation. The coal-type gas component was derived from in situ C3t-P1s source rocks, whereas the oil-type gas component might be derived from the carbonate rocks in the Lower Ordovician Majiagou Formation (O1m.

Simulation of a multistage fractured horizontal well in a water-bearing tight fractured gas reservoir under non-Darcy flow

Science.gov (United States)

Zhang, Rui-Han; Zhang, Lie-Hui; Wang, Rui-He; Zhao, Yu-Long; Huang, Rui

2018-06-01

Reservoir development for unconventional resources such as tight gas reservoirs is in increasing demand due to the rapid decline of production in conventional reserves. Compared with conventional reservoirs, fluid flow in water-bearing tight gas reservoirs is subject to more nonlinear multiphase flow and gas slippage in nano/micro matrix pores because of the strong collisions between rock and gas molecules. Economic gas production from tight gas reservoirs depends on extensive application of water-based hydraulic fracturing of horizontal wells, associated with non-Darcy flow at a high flow rate, geomechanical stress sensitivity of un-propped natural fractures, complex flow geometry and multiscale heterogeneity. How to efficiently and accurately predict the production performance of a multistage fractured horizontal well (MFHW) is challenging. In this paper, a novel multicontinuum, multimechanism, two-phase simulator is established based on unstructured meshes and the control volume finite element method to analyze the production performance of MFHWs. The multiple interacting continua model and discrete fracture model are coupled to integrate the unstimulated fractured reservoir, induced fracture networks (stimulated reservoir volumes, SRVs) and irregular discrete hydraulic fractures. Several simulations and sensitivity analyses are performed with the developed simulator for determining the key factors affecting the production performance of MFHWs. Two widely applied fracturing models, classic hydraulic fracturing which generates long double-wing fractures and the volumetric fracturing aimed at creating large SRVs, are compared to identify which of them can make better use of tight gas reserves.

High-pressure water electrolysis: Electrochemical mitigation of product gas crossover

International Nuclear Information System (INIS)

Schalenbach, Maximilian; Stolten, Detlef

2015-01-01

Highlights: • New technique to reduce gas crossover during water electrolysis • Increase of the efficiency of pressurized water electrolysis • Prevention of safety hazards due to explosive gas mixtures caused by crossover • Experimental realization for a polymer electrolyte membrane electrolyzer • Discussion of electrochemical crossover mitigation for alkaline water electrolysis - Abstract: Hydrogen produced by water electrolysis can be used as an energy carrier storing electricity generated from renewables. During water electrolysis hydrogen can be evolved under pressure at isothermal conditions, enabling highly efficient compression. However, the permeation of hydrogen through the electrolyte increases with operating pressure and leads to efficiency loss and safety hazards. In this study, we report on an innovative concept, where the hydrogen crossover is electrochemically mitigated by an additional electrode between the anode and the cathode of the electrolysis cell. Experimentally, the technique was applied to a proton exchange membrane water electrolyzer operated at a hydrogen pressure that was fifty times larger than the oxygen pressure. Therewith, the hydrogen crossover was reduced and the current efficiency during partial load operation was increased. The concept is also discussed for water electrolysis that is operated at balanced pressures, where the crossover of hydrogen and oxygen is mitigated using two additional electrodes

Analysis of Off Gas From Disintegration Process of Graphite Matrix by Electrochemical Method

International Nuclear Information System (INIS)

Tian Lifang; Wen Mingfen; Chen Jing

2010-01-01

Using electrochemical method with salt solutions as electrolyte, some gaseous substances (off gas) would be generated during the disintegration of graphite from high-temperature gas-cooled reactor fuel elements. The off gas is determined to be composed of H 2 , O 2 , N 2 , CO 2 and NO x by gas chromatography. Only about 1.5% graphite matrix is oxidized to CO 2 . Compared to the direct burning-graphite method, less off gas,especially CO 2 , is generated in the disintegration process of graphite by electrochemical method and the treatment of off gas becomes much easier. (authors)

Methods and systems for fuel production in electrochemical cells and reactors

Science.gov (United States)

Marina, Olga A.; Pederson, Larry R.

2018-01-30

Methods and systems for fuel, chemical, and/or electricity production from electrochemical cells are disclosed. A voltage is applied between an anode and a cathode of an electrochemical cell. The anode includes a metal or metal oxide electrocatalyst. Oxygen is supplied to the cathode, producing oxygen ions. The anode electrocatalyst is at least partially oxidized by the oxygen ions transported through an electrolyte from the cathode to the anode. A feed gas stream is supplied to the anode electrocatalyst, which is converted to a liquid fuel. The anode electrocatalyst is re-oxidized to higher valency oxides, or a mixture of oxide phases, by supplying the oxygen ions to the anode. The re-oxidation by the ions is controlled or regulated by the amount of voltage applied.

PP and PS seismic response from fractured tight gas reservoirs: a case study

International Nuclear Information System (INIS)

Jianming, Tang; Shaonan, Zhang; Li, Xiang-Yang

2008-01-01

In this paper, we present an example of using PP and PS converted-wave data recorded by digital micro-eletro-mechanical-systems (MEMS) to evaluate a fractured tight gas reservoir from the Xinchang gas field in Sichuan, China. For this, we analyse the variations in converted shear-wave splitting, Vp/Vs ratio and PP and PS impedance, as well as other attributes based on absorption and velocity dispersion. The reservoir formation is tight sandstone, buried at a depth of about 5000 m, and the converted-wave data reveal significant shear-wave splitting over the reservoir formation. We utilize a rotation technique to extract the shear-wave polarization and time delay from the data, and a small-window correlation method to build time-delay spectra that allow the generation of a time-delay section. At the reservoir formation, the shear-wave time delay is measured at 20 ms, about 15% shear-wave anisotropy, correlating with the known gas reservoirs. Furthermore, the splitting anomalies are consistent with the characteristics of other attributes such as Vp/Vs ratio and P- and S-wave acoustic and elastic impedance. The P-wave shows consistent low impedance over the reservoir formation, whilst the S-wave impedance shows relatively high impedance. The calculated gas indicator based on absorption and velocity dispersion yields a high correlation with the gas bearing formations. This confirms the benefit of multicomponent seismic data from digital MEMS sensors

Membrane-Coated Electrochemical Sensor for Corrosion Monitoring in Natural Gas Pipelines

Directory of Open Access Journals (Sweden)

J. Beck

2017-07-01

Full Text Available Electrochemical sensors can be used for a wide range of online in- situ process monitoring applications. However, the lack of a consistent electrolyte layer has previously limited electrochemical monitoring in gas and supercritical fluid streams. A solid state sensor is being designed that uses an ion conducting membrane to perform conductivity and corrosion measurements in natural gas pipelines up to 1000 psi. Initial results show that membrane conductivity measurements can be correlated directly to water content down to dew points of 1°C with good linearity. Corrosion monitoring can also be performed using methods such as linear polarization resistance and electrochemical impedance spectroscopy (EIS, though care must be taken in the electrode design to minimize deviation between sensors.

High temperature and pressure electrochemical test station

DEFF Research Database (Denmark)

Chatzichristodoulou, Christodoulos; Allebrod, Frank; Mogensen, Mogens Bjerg

2013-01-01

An electrochemical test station capable of operating at pressures up to 100 bars and temperatures up to 400 ◦C has been established. It enables control of the partial pressures and mass flow of O2, N2, H2, CO2, and H2O in a single or dual environment arrangement, measurements with highly corrosive...... media, as well as localized sampling of gas evolved at the electrodes for gas analysis. A number of safety and engineering design challenges have been addressed. Furthermore, we present a series of electrochemical cell holders that have been constructed in order to accommodate different types of cells...... and facilitate different types of electrochemical measurements. Selected examples of materials and electrochemical cells examined in the test station are provided, ranging from the evaluation of the ionic conductivity of liquid electrolytic solutions immobilized in mesoporous ceramic structures...

Conditioned medium from LS 174T goblet cells treated with oxyresveratrol strengthens tight junctions in Caco-2 cells.

Science.gov (United States)

Hwang, Dahyun; Jo, HyunA; Hwang, Seonwook; Kim, Jeong-Keun; Kim, In-Ho; Lim, Young-Hee

2017-01-01

Strengthening of intestinal tight junctions provides an effective barrier from the external environment. Goblet cell-derived trefoil factor 3 (TFF3) increases transepithelial resistance by upregulating the expression of tight junction proteins. Oxyresveratrol (OXY) is a hydroxyl-substituted stilbene found in the roots, leaves, stems, and fruit of many plants and known to have various biological activities. In this study, we investigated the strengthening effect of OXY on intestinal tight junctions through stimulation of TFF production in goblet cells. We prepared conditioned medium from LS 174T goblet cells treated with OXY (GCO-CM) and investigated the effect of GCO-CM on strengthening tight junctions of Caco-2 cells. The mRNA and protein expression levels of major tight junction components (claudin-1, occludin, and ZO-1) were measured by quantitative real-time PCR and western blotting, respectively. Transepithelial electric resistance (TEER) was measured using an ohm/V meter. Monolayer permeability was evaluated by paracellular transport of fluorescein isothiocyanate-dextran. OXY showed a strong antioxidant activity. It significantly increased the expression level of TFF3 in LS 174T goblet cells. GCO-CM prepared by treatment with 2.5, 5, and 10μg/ml OXY did not show cytotoxicity in Caco-2 cells. GCO-CM increased the mRNA and protein expression levels of claudin-1, occludin, and ZO-1. It also significantly increased tight junction integrity and reduced permeability in a dose-dependent manner. OXY stimulates the expression of TFF3 in goblet cells, which might increase the integrity of the intestinal tight junction barrier. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Hydrogen Gas Recycling for Energy Efficient Ammonia Recovery in Electrochemical Systems

NARCIS (Netherlands)

Kuntke, Philipp; Rodríguez Arredondo, Mariana; Widyakristi, Laksminarastri; Heijne, ter Annemiek; Sleutels, Tom H.J.A.; Hamelers, Hubertus V.M.; Buisman, Cees J.N.

2017-01-01

Recycling of hydrogen gas (H₂) produced at the cathode to the anode in an electrochemical system allows for energy efficient TAN (Total Ammonia Nitrogen) recovery. Using a H₂ recycling electrochemical system (HRES) we achieved high TAN transport rates at low energy input. At

Integration of seismic data and a triple porosity model for interpretation of tight gas formations in the Western Canada sedimentary basin

Energy Technology Data Exchange (ETDEWEB)

Castillo, Fernando; Aguilera, Roberto; Lawton, Don [University of Calgary (Canada)

2011-07-01

Due to the increased global demand for oil and gas, companies are looking to unconventional methods for exploring, drilling and refining these products. Unconventional reservoirs are found in the form of shale gas, coal bed methane and tight gas. This paper presents a model for evaluating various tight gas reservoirs in the Western Canada sedimentary basin (WCSB) by developing an equation. The proposed method integrates a triple porosity model with sonic, density and resistivity logs. The model uses petrographic data from work in the WCSB to determine the types of pores that are present in the tight rocks. The process also provides information on inter-well formation resistivity, porosity and water saturation to allow estimation of the amount of original gas in place. The results calculated from this study agreed with the actual deep resistivities of the WCSB Nikanassin group. This model can also be applied to other regions of the world that have similar characteristics to those of the WCSB.

Electrochemical photovoltaic cells and electrodes

Science.gov (United States)

Skotheim, Terje A.

1984-01-01

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.

Thermodynamic simulation of biomass gas steam reforming for a solid oxide fuel cell (SOFC system

Directory of Open Access Journals (Sweden)

A. Sordi

2009-12-01

Full Text Available This paper presents a methodology to simulate a small-scale fuel cell system for power generation using biomass gas as fuel. The methodology encompasses the thermodynamic and electrochemical aspects of a solid oxide fuel cell (SOFC, as well as solves the problem of chemical equilibrium in complex systems. In this case the complex system is the internal reforming of biomass gas to produce hydrogen. The fuel cell input variables are: operational voltage, cell power output, composition of the biomass gas reforming, thermodynamic efficiency, electrochemical efficiency, practical efficiency, the First and Second law efficiencies for the whole system. The chemical compositions, molar flows and temperatures are presented to each point of the system as well as the exergetic efficiency. For a molar water/carbon ratio of 2, the thermodynamic simulation of the biomass gas reforming indicates the maximum hydrogen production at a temperature of 1070 K, which can vary as a function of the biomass gas composition. The comparison with the efficiency of simple gas turbine cycle and regenerative gas turbine cycle shows the superiority of SOFC for the considered electrical power range.

Electrochemical cell structure including an ionomeric barrier

Science.gov (United States)

Lambert, Timothy N.; Hibbs, Michael

2017-06-20

An apparatus includes an electrochemical half-cell comprising: an electrolyte, an anode; and an ionomeric barrier positioned between the electrolyte and the anode. The anode may comprise a multi-electron vanadium phosphorous alloy, such as VP.sub.x, wherein x is 1-5. The electrochemical half-cell is configured to oxidize the vanadium and phosphorous alloy to release electrons. A method of mitigating corrosion in an electrochemical cell includes disposing an ionomeric barrier in a path of electrolyte or ion flow to an anode and mitigating anion accumulation on the surface of the anode.

Advanced impedance modeling of solid oxide electrochemical cells

DEFF Research Database (Denmark)

Graves, Christopher R.; Hjelm, Johan

2014-01-01

Impedance spectroscopy is a powerful technique for detailed study of the electrochemical and transport processes that take place in fuel cells and electrolysis cells, including solid oxide cells (SOCs). Meaningful analysis of impedance measurements is nontrivial, however, because a large number...... techniques to provide good guesses for the modeling parameters, like transforming the impedance data to the distribution of relaxation times (DRT), together with experimental parameter sensitivity studies, is the state-of-the-art approach to achieve good EC model fits. Here we present new impedance modeling...... electrode and 2-D gas transport models which have fewer unknown parameters for the same number of processes, (ii) use of a new model fitting algorithm, “multi-fitting”, in which multiple impedance spectra are fit simultaneously with parameters linked based on the variation of measurement conditions, (iii...

The tightness of the globe valves in the exploitations practice of the gas pipe-lines

International Nuclear Information System (INIS)

Pietrak, T.; Rudzki, Z.; Surmacz, W.

2006-01-01

Technological units of the Transit Gas Pipeline (i.e. Compressor Stations, Valve Stations, Stations or National Network Service Installations) have been fitted with Ball Valves as shut-off devices (block valves). Internal tightness of the valves' seat becomes major factor in securing proper service conditions during normal pipeline operation as well as for isolating of pipeline sections in emergency situations (loss of pipeline integrity or uncontrolled gas escape). Internal tightness of the valves is being inspected during scheduled maintenance of the pipeline units. Any leak revealed during inspection is being repaired, following instructions provided in the Manufacturer's Valve Manual. After a time, some cases have been identified, when repair of the revealed leak was found to be difficult, despite close following of the repair manuals. The paper presents analysis of the issue and corrective actions taken accordingly. (authors)

Characterizing tight-gas systems with production data: Wyoming, Utah, and Colorado

Science.gov (United States)

Nelson, Philip H.; Santus, Stephen L.; Baez, Luis; Beeney, Ken; Sonnenberg, Steve

2013-01-01

The study of produced fluids allows comparisons among tight-gas systems. This paper examines gas, oil, and water production data from vertical wells in 23 fields in five Rocky Mountain basins of the United States, mostly from wells completed before the year 2000. Average daily rates of gas, oil, and water production are determined two years and seven years after production begins in order to represent the interval in which gas production declines exponentially. In addition to the daily rates, results are also presented in terms of oil-to-gas and water-to-gas ratios, and in terms of the five-year decline in gas production rates and water-to-gas ratios. No attempt has been made to estimate the ultimate productivity of wells or fields. The ratio of gas production rates after seven years to gas production rates at two years is about one-half, with median ratios falling within a range of 0.4 to 0.6 in 16 fields. Oil-gas ratios show substantial variation among fields, ranging from dry gas (no oil) to wet gas to retrograde conditions. Among wells within fields, the oil-gas ratios vary by a factor of three to thirty, with the exception of the Lance Formation in Jonah and Pinedale fields, where the oil-gas ratios vary by less than a factor of two. One field produces water-free gas and a large fraction of wells in two other fields produce water-free gas, but most fields have water-gas ratios greater than 1 bbl/mmcf—greater than can be attributed to water dissolved in gas in the reservoir— and as high as 100 bbl/mmcf. The median water-gas ratio for fields increases moderately with time, but in individual wells water influx relative to gas is erratic, increasing greatly with time in many wells while remaining constant or decreasing in others.

Hydrogen storage material, electrochemically active material, electrochemical cell and electronic equipment

NARCIS (Netherlands)

2008-01-01

The invention relates to a hydrogen storage material comprising an alloy of magnesium. The invention further relates to an electrochemically active material and an electrochemical cell provided with at least one electrode comprising such a hydrogen storage material. Also, the invention relates to

Indirect-fired gas turbine bottomed with fuel cell

Science.gov (United States)

Micheli, P.L.; Williams, M.C.; Parsons, E.L.

1995-09-12

An indirect-heated gas turbine cycle is bottomed with a fuel cell cycle with the heated air discharged from the gas turbine being directly utilized at the cathode of the fuel cell for the electricity-producing electrochemical reaction occurring within the fuel cell. The hot cathode recycle gases provide a substantial portion of the heat required for the indirect heating of the compressed air used in the gas turbine cycle. A separate combustor provides the balance of the heat needed for the indirect heating of the compressed air used in the gas turbine cycle. Hot gases from the fuel cell are used in the combustor to reduce both the fuel requirements of the combustor and the NOx emissions therefrom. Residual heat remaining in the air-heating gases after completing the heating thereof is used in a steam turbine cycle or in an absorption refrigeration cycle. Some of the hot gases from the cathode can be diverted from the air-heating function and used in the absorption refrigeration cycle or in the steam cycle for steam generating purposes. 1 fig.

Structural-Diagenetic Controls on Fracture Opening in Tight Gas Sandstone Reservoirs, Alberta Foothills

Science.gov (United States)

Ukar, Estibalitz; Eichhubl, Peter; Fall, Andras; Hooker, John

2013-04-01

In tight gas reservoirs, understanding the characteristics, orientation and distribution of natural open fractures, and how these relate to the structural and stratigraphic setting are important for exploration and production. Outcrops provide the opportunity to sample fracture characteristics that would otherwise be unknown due to the limitations of sampling by cores and well logs. However, fractures in exhumed outcrops may not be representative of fractures in the reservoir because of differences in burial and exhumation history. Appropriate outcrop analogs of producing reservoirs with comparable geologic history, structural setting, fracture networks, and diagenetic attributes are desirable but rare. The Jurassic to Lower Cretaceous Nikanassin Formation from the Alberta Foothills produces gas at commercial rates where it contains a network of open fractures. Fractures from outcrops have the same diagenetic attributes as those observed in cores fractures relative to fold cores, hinges and limbs, 2) compare the distribution and attributes of fractures in outcrop vs. core samples, 3) estimate the timing of fracture formation relative to the evolution of the fold-and-thrust belt, and 4) estimate the degradation of fracture porosity due to postkinematic cementation. Cathodoluminescence images of cemented fractures in both outcrop and core samples reveal several generations of quartz and ankerite cement that is synkinematic and postkinematic relative to fracture opening. Crack-seal textures in synkinematic quartz are ubiquitous, and well-developed cement bridges abundant. Fracture porosity may be preserved in fractures wider than ~100 microns. 1-D scanlines in outcrop and core samples indicate fractures are most abundant within small parasitic folds within larger, tight, mesoscopic folds. Fracture intensity is lower away from parasitic folds; intensity progressively decreases from the faulted cores of mesoscopic folds to their forelimbs, with lowest intensities within

Investigation of hydraulic fracture re-orientation effects in tight gas reservoirs

Energy Technology Data Exchange (ETDEWEB)

Hagemann, B.; Wegner, J.; Ganzer, L. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). ITE

2013-08-01

In tight gas formations where the low matrix permeability prevents successful and economic production rates, hydraulic fracturing is required to produce a well at economic rates. The initial fracture opens in the direction of minimum stress and propagates into the direction of maximum stress. As production from the well and its initial fracture declines, re-fracturing treatments are required to accelerate recovery. The orientation of the following hydraulic fracture depends on the actual stress-state of the formation in the vicinity of the wellbore. Previous investigations by Elbel and Mack (1993) demonstrated that the stress alters during depletion and a stress reversal region appears. This behavior causes a different fracture orientation of the re-fracturing operation. For the investigation of re-fracture orientation a two-dimensional reservoir model has been designed using COMSOL Multiphysics. The model represents a fractured vertical well in a tight gas reservoir of infinite thickness. A time dependent study was set up to simulate the reservoir depletion by the production from the fractured well. The theory of poroelasticity was used to couple the fluid flow and geo-mechanical behavior. The stress state is initially defined as uniform and the attention is concentrated to the alteration of stress due to the lowered pore pressure. Different cases with anisotropic and heterogeneous permeability are set up to determine its significance. The simulation shows that an elliptical shaped drainage area appears around the fracture. The poroelastic behavior effects that the stress re-orientates and a stress reversal region originates, if the difference between minimum and maximum horizontal stresses is small. The consideration of time indicates that the dimension of the region initially extends fast until it reaches its maximum. Subsequently, the stress reversal region's extent shrinks slowly until it finally disappears. The reservoir characteristics, e.g. the

Enhanced Recovery in Tight Gas Reservoirs using Maxwell-Stefan Equations

Science.gov (United States)

Santiago, C. J. S.; Kantzas, A.

2017-12-01

Due to the steep production decline in unconventional gas reservoirs, enhanced recovery (ER) methods are receiving great attention from the industry. Wet gas or liquid rich reservoirs are the preferred ER candidates due to higher added value from natural gas liquids (NGL) production. ER in these reservoirs has the potential to add reserves by improving desorption and displacement of hydrocarbons through the medium. Nevertheless, analysis of gas transport at length scales of tight reservoirs is complicated because concomitant mechanisms are in place as pressure declines. In addition to viscous and Knudsen diffusion, multicomponent gas modeling includes competitive adsorption and molecular diffusion effects. Most models developed to address these mechanisms involve single component or binary mixtures. In this study, ER by gas injection is investigated in multicomponent (C1, C2, C3 and C4+, CO2 and N2) wet gas reservoirs. The competing effects of Knudsen and molecular diffusion are incorporated by using Maxwell-Stefan equations and the Dusty-Gas approach. This model was selected due to its superior properties on representing the physics of multicomponent gas flow, as demonstrated during the presented model validation. Sensitivity studies to evaluate adsorption, reservoir permeability and gas type effects are performed. The importance of competitive adsorption on production and displacement times is demonstrated. In the absence of adsorption, chromatographic separation is negligible. Production is merely dictated by competing effects between molecular and Knudsen diffusion. Displacement fronts travel rapidly across the medium. When adsorption effects are included, molecules with lower affinity to the adsorption sites will be produced faster. If the injected gas is inert (N2), an increase in heavier fraction composition occurs in the medium. During injection of adsorbing gases (CH4 and CO2), competitive adsorption effects will contribute to improved recovery of heavier

Electrochemical cell

Science.gov (United States)

Kaun, T.D.

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 to 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 to 10 volume % of the electrode, an additive from the materials of graphitized carbon, aluminum-iron alloy, and/or magnesium oxide.

A mathematical model for hydrogen evolution in an electrochemical cell and experimental validation

International Nuclear Information System (INIS)

Mahmut D Mat; Yuksel Kaplan; Beycan Ibrahimoglu; Nejat Veziroglu; Rafig Alibeyli; Sadiq Kuliyev

2006-01-01

Electrochemical reaction is largely employed in various industrial areas such as hydrogen production, chlorate process, electroplating, metal purification etc. Most of these processes often take place with gas evaluation on the electrodes. Presence of gas phase in the liquid phase makes the problem two-phase flow which is much knowledge available from heat transfer and fluid mechanics studies. The motivation of this study is to investigate hydrogen release in an electrolysis processes from two-phase flow point of view and investigate effect of gas release on the electrolysis process. Hydrogen evolution, flow field and current density distribution in an electrochemical cell are investigated with a two-phase flow model. The mathematical model involves solutions of transport equations for the variables of each phase with allowance for inter phase transfer of mass and momentum. An experimental set-up is established to collect data to validate and improve the mathematical model. Void fraction is determined from measurement of resistivity changes in the system due to the presence of bubbles. A good agreement is obtained between numerical results and experimental data. (authors)

An unconventional rate decline approach for tight and fracture-dominated gas wells

Energy Technology Data Exchange (ETDEWEB)

Duong, A.N. [ConocoPhillips Canada Resources Corp., Calgary, AB (Canada)

2010-07-01

In both Canada and the United States, unconventional gas reservoirs, especially wet shale gas are being aggressively pursued for new development. Forecasting production and estimating reserves accurately for these resource plays has become increasingly important and necessary. This paper introduced an empirically derived decline model based on a long-term linear flow in a large number of wells in tight and shale gas reservoirs. A new methodology was developed for production analysis and forecasting of unconventional reservoirs based on this model. In order to represent any uncertainty in reserve estimation, this method also utilized probability distributions of reserves in forecasting resource plays. The paper discussed the methodology development including long-term linear flow and their associated equations, as well as several field examples including a gas retrograde case and individual well analysis. Result comparisons and a discussion of the results were also presented. It was concluded that pressure initialization used in numerical modeling based on fluid gradients may have been incorrect. Results from such numerical modeling may not be representative of the shale gas flow characteristics. 24 refs., 2 tabs., 15 figs., 1 appendix.

Tight junctions and human diseases.

Science.gov (United States)

Sawada, Norimasa; Murata, Masaki; Kikuchi, Keisuke; Osanai, Makoto; Tobioka, Hirotoshi; Kojima, Takashi; Chiba, Hideki

2003-09-01

Tight junctions are intercellular junctions adjacent to the apical end of the lateral membrane surface. They have two functions, the barrier (or gate) function and the fence function. The barrier function of tight junctions regulates the passage of ions, water, and various macromolecules, even of cancer cells, through paracellular spaces. The barrier function is thus relevant to edema, jaundice, diarrhea, and blood-borne metastasis. On the other hand, the fence function maintains cell polarity. In other words, tight junctions work as a fence to prevent intermixing of molecules in the apical membrane with those in the lateral membrane. This function is deeply involved in cancer cell biology, in terms of loss of cell polarity. Of the proteins comprising tight junctions, integral membrane proteins occludin, claudins, and JAMs have been recently discovered. Of these molecules, claudins are exclusively responsible for the formation of tight-junction strands and are connected with the actin cytoskeleton mediated by ZO-1. Thus, both functions of tight junctions are dependent on the integrity of the actin cytoskeleton as well as ATP. Mutations in the claudin14 and the claudin16 genes result in hereditary deafness and hereditary hypomagnesemia, respectively. Some pathogenic bacteria and viruses target and affect the tight-junction function, leading to diseases. In this review, the relationship between tight junctions and human diseases is summarized.

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

Directory of Open Access Journals (Sweden)

Jun Wang

2012-04-01

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

Tight multilattices calculated by extended-cell cylindrization

Energy Technology Data Exchange (ETDEWEB)

Segev, M; Carmona, S

1983-01-01

Among the common features of advanced LWR concepts are the tightness of lattices and the symbiotic setting of different fuels. Such symbioses often come in the form of multilattices, whose numerically-repeated unit is a configuration of several pins, typically with one pin type at the center and pins of a second type surrounding the center pin. If this extended-cell (EC) unit is cylindricized, then a simple transport calculation of the unit will be possible. If the lattice of such units is tight, there is further an a priori reason to expect the cylindrization to introduce only a small distortion of the true neutron fluxes in the lattice. A strict numerical validation of the EC cylindrization approximation is impractical, but similar validations can be carried out for regular lattices, viewed as being made up of multicell units whose centers are moderators and whose peripheries are fuel pins. In these comparisons the EC cylindrization approximation gives good results.

The RealGas and RealGasH2O Options of the TOUGH+ Code for the Simulation of Coupled Fluid and Heat Flow in Tight/Shale Gas Systems

Energy Technology Data Exchange (ETDEWEB)

Moridis, George; Freeman, Craig

2013-09-30

We developed two new EOS additions to the TOUGH+ family of codes, the RealGasH2O and RealGas . The RealGasH2O EOS option describes the non-isothermal two-phase flow of water and a real gas mixture in gas reservoirs, with a particular focus in ultra-tight (such as tight-sand and shale gas) reservoirs. The gas mixture is treated as either a single-pseudo-component having a fixed composition, or as a multicomponent system composed of up to 9 individual real gases. The RealGas option has the same general capabilities, but does not include water, thus describing a single-phase, dry-gas system. In addition to the standard capabilities of all members of the TOUGH+ family of codes (fully-implicit, compositional simulators using both structured and unstructured grids), the capabilities of the two codes include: coupled flow and thermal effects in porous and/or fractured media, real gas behavior, inertial (Klinkenberg) effects, full micro-flow treatment, Darcy and non-Darcy flow through the matrix and fractures of fractured media, single- and multi-component gas sorption onto the grains of the porous media following several isotherm options, discrete and fracture representation, complex matrix-fracture relationships, and porosity-permeability dependence on pressure changes. The two options allow the study of flow and transport of fluids and heat over a wide range of time frames and spatial scales not only in gas reservoirs, but also in problems of geologic storage of greenhouse gas mixtures, and of geothermal reservoirs with multi-component condensable (H2O and CH4) and non-condensable gas mixtures. The codes are verified against available analytical and semi-analytical solutions. Their capabilities are demonstrated in a series of problems of increasing complexity, ranging from isothermal flow in simpler 1D and 2D conventional gas reservoirs, to non-isothermal gas flow in 3D fractured shale gas reservoirs involving 4 types of fractures, micro-flow, non-Darcy flow and gas

3D-fibroblast tissues constructed by a cell-coat technology enhance tight-junction formation of human colon epithelial cells.

Science.gov (United States)

Matsusaki, Michiya; Hikimoto, Daichi; Nishiguchi, Akihiro; Kadowaki, Koji; Ohura, Kayoko; Imai, Teruko; Akashi, Mitsuru

2015-02-13

Caco-2, human colon carcinoma cell line, has been widely used as a model system for intestinal epithelial permeability because Caco-2 cells express tight-junctions, microvilli, and a number of enzymes and transporters characteristic of enterocytes. However, the functional differentiation and polarization of Caco-2 cells to express sufficient tight-junctions (a barrier) usually takes over 21 days in culture. This may be due to the cell culture environment, for example inflammation induced by plastic petri dishes. Three-dimensional (3D) sufficient cell microenvironments similar to in vivo natural conditions (proteins and cells), will promote rapid differentiation and higher functional expression of tight junctions. Herein we report for the first time an enhancement in tight-junction formation by 3D-cultures of Caco-2 cells on monolayered (1L) and eight layered (8L) normal human dermal fibroblasts (NHDF). Trans epithelial electric resistance (TEER) of Caco-2 cells was enhanced in the 3D-cultures, especially 8L-NHDF tissues, depending on culture times and only 10 days was enough to reach the same TEER value of Caco-2 monolayers after a 21 day incubation. Relative mRNA expression of tight-junction proteins of Caco-2 cells on 3D-cultures showed higher values than those in monolayer structures. Transporter gene expression patterns of Caco-2 cells on 3D-constructs were almost the same as those of Caco-2 monolayers, suggesting that there was no effect of 3D-cultures on transporter protein expression. The expression correlation between carboxylesterase 1 and 2 in 3D-cultures represented similar trends with human small intestines. The results of this study clearly represent a valuable application of 3D-Caco-2 tissues for pharmaceutical applications. Copyright © 2015 Elsevier Inc. All rights reserved.

GPU-Based Computation of Formation Pressure for Multistage Hydraulically Fractured Horizontal Wells in Tight Oil and Gas Reservoirs

Directory of Open Access Journals (Sweden)

Rongwang Yin

2018-01-01

Full Text Available A mathematical model for multistage hydraulically fractured horizontal wells (MFHWs in tight oil and gas reservoirs was derived by considering the variations in the permeability and porosity of tight oil and gas reservoirs that depend on formation pressure and mixed fluid properties and introducing the pseudo-pressure; analytical solutions were presented using the Newman superposition principle. The CPU-GPU asynchronous computing model was designed based on the CUDA platform, and the analytic solution was decomposed into infinite summation and integral forms for parallel computation. Implementation of this algorithm on an Intel i5 4590 CPU and NVIDIA GT 730 GPU demonstrates that computation speed increased by almost 80 times, which meets the requirement for real-time calculation of the formation pressure of MFHWs.

The behavior of electrochemical cell resistance

International Nuclear Information System (INIS)

Ritley, K.A.; Dull, P.M.; Weber, M.H.; Carroll, M.; Hurst, J.J.; Lynn, K.G.

1990-01-01

Knowledge of the basic electrochemical behavior found in typical cold fusion experiments is important to understanding and preventing experimental errors. For a Pd/LiOH(D)/Pt electrochemical cell, the applied cell voltage/current relationship (the effective cell resistance) does not obey Ohm's law directly, but instead exhibits a complicated response to the current, voltage, temperature, electrolyte conductance, and other factors. Failure to properly consider this response can possibly result in errors that could affect the heat balance in calorimetry and temperature measurement experiments. Measurements of this response under varying voltage, temperature, and electrolyte conductivity conditions are reported. A plausible scenario in which the temperature dependence of the effective cell resistance can either exaggerate or ameliorate novel exothermic processes is suggested

Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface ground water: background, base cases, shallow reservoirs, short-term gas and water transport

Science.gov (United States)

Researchers examined gas and water transport between a deep tight shale gas reservoir and a shallow overlying aquifer in the two years following hydraulic fracturing, assuming a pre-existing connecting pathway.

Behavior of tight-junction, adherens-junction and cell polarity proteins during HNF-4α-induced epithelial polarization

International Nuclear Information System (INIS)

Satohisa, Seiro; Chiba, Hideki; Osanai, Makoto; Ohno, Shigeo; Kojima, Takashi; Saito, Tsuyoshi; Sawada, Norimasa

2005-01-01

We previously reported that expression of tight-junction molecules occludin, claudin-6 and claudin-7, as well as establishment of epithelial polarity, was triggered in mouse F9 cells expressing hepatocyte nuclear factor (HNF)-4α [H. Chiba, T. Gotoh, T. Kojima, S. Satohisa, K. Kikuchi, M. Osanai, N. Sawada. Hepatocyte nuclear factor (HNF)-4α triggers formation of functional tight junctions and establishment of polarized epithelial morphology in F9 embryonal carcinoma cells, Exp. Cell Res. 286 (2003) 288-297]. Using these cells, we examined in the present study behavior of tight-junction, adherens-junction and cell polarity proteins and elucidated the molecular mechanism behind HNF-4α-initiated junction formation and epithelial polarization. We herein show that not only ZO-1 and ZO-2, but also ZO-3, junctional adhesion molecule (JAM)-B, JAM-C and cell polarity proteins PAR-3, PAR-6 and atypical protein kinase C (aPKC) accumulate at primordial adherens junctions in undifferentiated F9 cells. In contrast, CRB3, Pals1 and PATJ appeared to exhibit distinct subcellular localization in immature cells. Induced expression of HNF-4α led to translocation of these tight-junction and cell polarity proteins to beltlike tight junctions, where occludin, claudin-6 and claudin-7 were assembled, in differentiated cells. Interestingly, PAR-6, aPKC, CRB3 and Pals1, but not PAR-3 or PATJ, were also concentrated on the apical membranes in differentiated cells. These findings indicate that HNF-4α provokes not only expression of tight-junction adhesion molecules, but also modulation of subcellular distribution of junction and cell polarity proteins, resulting in junction formation and epithelial polarization

Use of Electrochemical Impedance Spectroscopy for the Evaluation of Performance of PEM Fuel Cells Based on Carbon Cloth Gas Diffusion Electrodes

Directory of Open Access Journals (Sweden)

Saverio Latorrata

2018-01-01

Full Text Available Polymer electrolyte membrane fuel cells (PEMFCs have attracted great attention in the last two decades as valuable alternative energy generators because of their high efficiencies and low or null pollutant emissions. In the present work, two gas diffusion electrodes (GDEs for PEMFCs were prepared by using an ink containing carbon-supported platinum in the catalytic phase which was sprayed onto a carbon cloth substrate. Two aerograph nozzles, with different sizes, were used. The prepared GDEs were assembled into a fuel cell lab prototype with commercial electrolyte and bipolar plates and tested alternately as anode and cathode. Polarization measurements and electrochemical impedance spectroscopy (EIS were performed on the running hydrogen-fed PEMFC from open circuit voltage to high current density. Experimental impedance spectra were fitted with an equivalent circuit model by using ZView software which allowed to get crucial parameters for the evaluation of fuel cell performance, such as ohmic resistance, charge transfer, and mass transfer resistance, whose trends have been studied as a function of the applied current density.

A new method in predicting productivity of multi-stage fractured horizontal well in tight gas reservoirs

Directory of Open Access Journals (Sweden)

Yunsheng Wei

2016-10-01

Full Text Available The generally accomplished technique for horizontal wells in tight gas reservoirs is by multi-stage hydraulic fracturing, not to mention, the flow characteristics of a horizontal well with multiple transverse fractures are very intricate. Conventional methods, well as an evaluation unit, are difficult to accurately predict production capacity of each fracture and productivity differences between wells with a different number of fractures. Thus, a single fracture sets the minimum evaluation unit, matrix, fractures, and lateral wellbore model that are then combined integrally to approximate horizontal well with multiple transverse hydraulic fractures in tight gas reservoirs. This paper presents a new semi-analytical methodology for predicting the production capacity of a horizontal well with multiple transverse hydraulic fractures in tight gas reservoirs. Firstly, a mathematical flow model used as a medium, which is disturbed by finite conductivity vertical fractures and rectangular shaped boundaries, is established and explained by the Fourier integral transform. Then the idea of a single stage fracture analysis is incorporated to establish linear flow model within a single fracture with a variable rate. The Fredholm integral numerical solution is applicable for the fracture conductivity function. Finally, the pipe flow model along the lateral wellbore is adapted to couple multi-stages fracture mathematical models, and the equation group of predicting productivity of a multi-stage fractured horizontal well. The whole flow process from the matrix to bottom-hole and production interference between adjacent fractures is also established. Meanwhile, the corresponding iterative algorithm of the equations is given. In this case analysis, the productions of each well and fracture are calculated under the different bottom-hole flowing pressure, and this method also contributes to obtaining the distribution of pressure drop and production for every

Contraption and Prediction of Exhalation Tight Brownstone in Exhalation Cistern

OpenAIRE

XhingZhiwang, -; Xuchao, -

2012-01-01

The reservoir connate water saturation is high and gas wells generally produce water which seriously affects the productivity of gas wells in Xujiahe tight sandstone gas reservoirs in Sichuan Basin. Take the sixth formation for example, there are 39 wells producing water unequally in the 42 commissioning wells, and the excessive water production leads to the production of the gas well declining rapidly. Studying of the mechanism of water production in tight sandstone gas reservoirs and predic...

Fabrication of a miniaturized cell using microsystem technologies for electrochemical applications

International Nuclear Information System (INIS)

Lakard, Boris; Jeannot, Jean-Claude; Spajer, Michel; Herlem, Guillaume; Labachelerie, Michel de; Blind, Pascal; Fahys, Bernard

2005-01-01

A new type of electrochemical cell has been developed for use in electrochemical, chemical and biological applications. Using a platinum microelectrode as working electrode, this cell incorporates a silver microelectrode as reference electrode. These microelectrodes, whose area is equal to 1 μm 2 , were fabricated using photolithography, sputtering, and focused ion beam (FIB) technologies since these micro-fabrication techniques allow us to develop miniaturized electrochemical cells useful either for nanoelectrochemistry or biosensors applications. In this study, we show it is possible to coat a surface by chemical or biological compounds by immersing the microelectrodes in a solution, then setting a difference of potential between the two microelectrodes of the cell. For example, we used this miniaturized cell to realize the electrochemical polymerization of aniline into polyaniline to show that this electrochemical cell is efficient to coat a surface with a thin film of polymer

Microbial Electrolysis Cells for High Yield Hydrogen Gas Production from Organic Matter

NARCIS (Netherlands)

Logan, B.E.; Call, D.; Cheng, S.; Hamelers, H.V.M.; Sleutels, T.H.J.A.; Jeremiasse, A.W.; Rozendal, R.A.

2008-01-01

The use of electrochemically active bacteria to break down organic matter, combined with the addition of a small voltage (>0.2 V in practice) in specially designed microbial electrolysis cells (MECs), can result in a high yield of hydrogen gas. While microbial electrolysis was invented only a few

Neural Cell Chip Based Electrochemical Detection of Nanotoxicity.

Science.gov (United States)

Kafi, Md Abdul; Cho, Hyeon-Yeol; Choi, Jeong Woo

2015-07-02

Development of a rapid, sensitive and cost-effective method for toxicity assessment of commonly used nanoparticles is urgently needed for the sustainable development of nanotechnology. A neural cell with high sensitivity and conductivity has become a potential candidate for a cell chip to investigate toxicity of environmental influences. A neural cell immobilized on a conductive surface has become a potential tool for the assessment of nanotoxicity based on electrochemical methods. The effective electrochemical monitoring largely depends on the adequate attachment of a neural cell on the chip surfaces. Recently, establishment of integrin receptor specific ligand molecules arginine-glycine-aspartic acid (RGD) or its several modifications RGD-Multi Armed Peptide terminated with cysteine (RGD-MAP-C), C(RGD)₄ ensure farm attachment of neural cell on the electrode surfaces either in their two dimensional (dot) or three dimensional (rod or pillar) like nano-scale arrangement. A three dimensional RGD modified electrode surface has been proven to be more suitable for cell adhesion, proliferation, differentiation as well as electrochemical measurement. This review discusses fabrication as well as electrochemical measurements of neural cell chip with particular emphasis on their use for nanotoxicity assessments sequentially since inception to date. Successful monitoring of quantum dot (QD), graphene oxide (GO) and cosmetic compound toxicity using the newly developed neural cell chip were discussed here as a case study. This review recommended that a neural cell chip established on a nanostructured ligand modified conductive surface can be a potential tool for the toxicity assessments of newly developed nanomaterials prior to their use on biology or biomedical technologies.

Neural Cell Chip Based Electrochemical Detection of Nanotoxicity

Directory of Open Access Journals (Sweden)

Md. Abdul Kafi

2015-07-01

Full Text Available Development of a rapid, sensitive and cost-effective method for toxicity assessment of commonly used nanoparticles is urgently needed for the sustainable development of nanotechnology. A neural cell with high sensitivity and conductivity has become a potential candidate for a cell chip to investigate toxicity of environmental influences. A neural cell immobilized on a conductive surface has become a potential tool for the assessment of nanotoxicity based on electrochemical methods. The effective electrochemical monitoring largely depends on the adequate attachment of a neural cell on the chip surfaces. Recently, establishment of integrin receptor specific ligand molecules arginine-glycine-aspartic acid (RGD or its several modifications RGD-Multi Armed Peptide terminated with cysteine (RGD-MAP-C, C(RGD4 ensure farm attachment of neural cell on the electrode surfaces either in their two dimensional (dot or three dimensional (rod or pillar like nano-scale arrangement. A three dimensional RGD modified electrode surface has been proven to be more suitable for cell adhesion, proliferation, differentiation as well as electrochemical measurement. This review discusses fabrication as well as electrochemical measurements of neural cell chip with particular emphasis on their use for nanotoxicity assessments sequentially since inception to date. Successful monitoring of quantum dot (QD, graphene oxide (GO and cosmetic compound toxicity using the newly developed neural cell chip were discussed here as a case study. This review recommended that a neural cell chip established on a nanostructured ligand modified conductive surface can be a potential tool for the toxicity assessments of newly developed nanomaterials prior to their use on biology or biomedical technologies.

CFD analysis of a solid oxide fuel cell with internal reforming: Coupled interactions of transport, heterogeneous catalysis and electrochemical processes

Energy Technology Data Exchange (ETDEWEB)

Janardhanan, Vinod M.; Deutschmann, Olaf [Institute for Chemical Technology and Polymer Chemistry, Engesserstr. 20, D-76131 Karlsruhe, University of Karlsruhe (TH) (Germany)

2006-11-22

Direct internal reforming in solid oxide fuel cell (SOFC) results in increased overall efficiency of the system. Present study focus on the chemical and electrochemical process in an internally reforming anode supported SOFC button cell running on humidified CH{sub 4} (3% H{sub 2} O). The computational approach employs a detailed multi-step model for heterogeneous chemistry in the anode, modified Butler-Volmer formalism for the electrochemistry and Dusty Gas Model (DGM) for the porous media transport. Two-dimensional elliptic model equations are solved for a button cell configuration. The electrochemical model assumes hydrogen as the only electrochemically active species. The predicted cell performances are compared with experimental reports. The results show that model predictions are in good agreement with experimental observation except the open circuit potentials. Furthermore, the steam content in the anode feed stream is found to have remarkable effect on the resulting overpotential losses and surface coverages of various species at the three-phase boundary. (author)

CFD analysis of a solid oxide fuel cell with internal reforming: Coupled interactions of transport, heterogeneous catalysis and electrochemical processes

Science.gov (United States)

Janardhanan, Vinod M.; Deutschmann, Olaf

Direct internal reforming in solid oxide fuel cell (SOFC) results in increased overall efficiency of the system. Present study focus on the chemical and electrochemical process in an internally reforming anode supported SOFC button cell running on humidified CH 4 (3% H 2 O). The computational approach employs a detailed multi-step model for heterogeneous chemistry in the anode, modified Butler-Volmer formalism for the electrochemistry and Dusty Gas Model (DGM) for the porous media transport. Two-dimensional elliptic model equations are solved for a button cell configuration. The electrochemical model assumes hydrogen as the only electrochemically active species. The predicted cell performances are compared with experimental reports. The results show that model predictions are in good agreement with experimental observation except the open circuit potentials. Furthermore, the steam content in the anode feed stream is found to have remarkable effect on the resulting overpotential losses and surface coverages of various species at the three-phase boundary.

Advanced gas-emission anode design for microfluidic fuel cell eliminating bubble accumulation

International Nuclear Information System (INIS)

Zhang, Hao; Xuan, Jin; Wang, Huizhi; Leung, Dennis Y C; Xu, Hong; Zhang, Li

2017-01-01

A microfluidic fuel cell is a low cost, easily fabricated energy device and is considered a promising energy supplier for portable electronics. However, the currently developed microfluidic fuel cells that are fed with hydrocarbon fuels are confronted with a bubble problem especially when operating at high current density conditions. In this work, a gas-emission anode is presented to eliminate the gas accumulation at the anode. This gas-emission anode is verified as a valid design for discharging gaseous products, which is especially beneficial for stable operation of microfluidic fuel cells. The electrochemical performance of a counter-flow microfluidic fuel cell equipped with a gas-emission anode was measured. The results indicate that the specific design of the gas-emission anode is essential for reducing the oxygen reduction reaction parasitic effect at the anode. Fuel utilization of 76.4% was achieved at a flow rate of 0.35 µ l min −1 . Current–voltage curves of single electrodes were measured and the parasitic effect at the anode was identified as the main performance limiting factor in the presented anode design. (paper)

Simultaneously Coupled Mechanical-Electrochemical-Thermal Simulation of Lithium-Ion Cells: Preprint

Energy Technology Data Exchange (ETDEWEB)

Zhang, Chao; Santhanagopalan, Shriram; Sprague, Michael A.; Pesaran, Ahmad A.

2016-08-01

Understanding the combined electrochemical-thermal and mechanical response of a system has a variety of applications, for example, structural failure from electrochemical fatigue and the potential induced changes of material properties. For lithium-ion batteries, there is an added concern over the safety of the system in the event of mechanical failure of the cell components. In this work, we present a generic multi-scale simultaneously coupled mechanical-electrochemical-thermal model to examine the interaction between mechanical failure and electrochemical-thermal responses. We treat the battery cell as a homogeneous material while locally we explicitly solve for the mechanical response of individual components using a homogenization model and the electrochemical-thermal responses using an electrochemical model for the battery. A benchmark problem is established to demonstrate the proposed modeling framework. The model shows the capability to capture the gradual evolution of cell electrochemical-thermal responses, and predicts the variation of those responses under different short-circuit conditions.

Analysis of Gas Leakage and Current Loss of Solid Oxide Fuel Cells by Screen Printing

DEFF Research Database (Denmark)

Jia, Chuan; Han, Minfang; Chen, Ming

2017-01-01

Two types of anode supported solid oxide fuel cell (SOFC) NiO-YSZ/YSZ/GDC/LSCF with the same structure and different manufacturing process were tested. Gas leakage was suspected for cells manufactured with screen printing technique. Effective leak current densities for both types of cells were...... calculated. Their performances of electrochemical impedance spectroscopy (EIS) were compared and distribution function of relaxation times (DRT) technique was also used to find the clue of gas leakage. Finally, thinning and penetrating holes were observed in electrolyte layer, which confirmed the occurrence...

Design philosophy and practice of asymmetrical 3D fracturing and random fracturing: A case study of tight sand gas reservoirs in western Sichuan Basin

Directory of Open Access Journals (Sweden)

Jianchun Guo

2015-03-01

Full Text Available At present two technical models are commonly taken in tight gas reservoir stimulation: conventional massive fracturing and SRV fracturing, but how to select a suitable fracturing model suitable for reservoir characteristics is still a question waiting to be answered. In this paper, based on the analysis of geological characteristics and seepage mechanism of tight gas and shale gas reservoirs, the differences between stimulation philosophy of tight gas reservoirs and shale reservoirs are elucidated, and the concept that a suitable stimulation model should be selected based on reservoir geological characteristics and seepage mechanism aiming at maximally improving the seepage capability of a reservoir. Based on this concept, two fracturing design methods were proposed for two tight gas reservoirs in western Sichuan Basin: asymmetrical 3D fracturing design (A3DF for the middle-shallow Upper Jurassic Penglaizhen Fm stacked reservoirs in which the hydraulic fractures can well match the sand spatial distribution and seepage capability of the reservoirs; SRV fracturing design which can increase fracture randomness in the sandstone and shale laminated reservoirs for the 5th Member of middle-deep Upper Triassic Xujiahe Fm. Compared with that by conventional fracturing, the average production of horizontal wells fractured by A3DF increased by 41%, indicating that A3DF is appropriate for gas reservoir development in the Penglaizhen Fm; meanwhile, the average production per well of the 5th Member of the Xujiahe Fm was 2.25 × 104 m3/d after SRV fracturing, showing that the SRV fracturing is a robust technical means for the development of this reservoir.

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

Science.gov (United States)

Gering, Kevin L

2013-08-27

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.

Foam Based Gas Diffusion Electrodes for Reversible Alkaline Electrolysis Cells

DEFF Research Database (Denmark)

Allebrod, Frank; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

2014-01-01

Alkaline electrolysis cells operated at 250 °C and 40 bar have shown to be able to convert electrical energy into chemical energy in the form of hydrogen at very high efficiencies and power densities. Foam based gas diffusion electrodes and a liquid immobilized electrolyte allow the operation...... of the newly designed electrolysis cell as a fuel cell, but condensation of steam may lead to blocked pores, thereby inhibiting gas diffusion and decreasing the performance of the cell. In the here presented work we present the application of a hydrophobic, porous, and electro-catalytically active layer...... the electrochemical characteristics of the cell. The thickness of the electrolyte matrix was reduced to 200 µm, thereby achieving a serial resistance and area specific resistance as low as 60 mΩ cm2 and 150 mΩ cm2, respectively, at a temperature of 200 °C and 20 bar pressure. A new production method was developed...

Symposium on Electrochemical and Thermal Modeling of Battery, Fuel Cell, and Photoenergy Conversion Systems, San Diego, CA, Oct. 20-22, 1986, Proceedings

Science.gov (United States)

Selman, J. Robert; Maru, Hans C.

Papers are presented on modeling of the zinc chlorine battery, design modeling of zinc/bromine battery systems, the modeling of aluminum-air battery systems, and a point defect model for a nickel electrode structure. Also considered are the impedance of a tubular electrode under laminar flow, mathematical modeling of a LiAl/Cl2 cell with a gas diffusion Cl2 electrode, ultrahigh power batteries, and battery thermal modeling. Other topics include an Na/beta-alumina/NaAlCl4, Cl2/C circulating cell, leakage currents in electrochemical systems having common electrodes, modeling for CO poisoning of a fuel cell anode, electrochemical corrosion of carbonaceous materials, and electrolyte management in molten carbonate fuel cells.

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

Science.gov (United States)

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

2013-09-17

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

Proteomic Analysis to Identify Tightly-Bound Cell Wall Protein in Rice Calli

OpenAIRE

Cho, Won Kyong; Hyun, Tae Kyung; Kumar, Dhinesh; Rim, Yeonggil; Chen, Xiong Yan; Jo, Yeonhwa; Kim, Suwha; Lee, Keun Woo; Park, Zee-Yong; Lucas, William J.; Kim, Jae-Yean

2015-01-01

Rice is a model plant widely used for basic and applied research programs. Plant cell wall proteins play key roles in a broad range of biological processes. However, presently, knowledge on the rice cell wall proteome is rudimentary in nature. In the present study, the tightly-bound cell wall proteome of rice callus cultured cells using sequential extraction protocols was developed using mass spectrometry and bioinformatics methods, leading to the identification of 1568 candidate proteins. Ba...

Fuel cells: new technology of natural gas for energetical building; Pilas de combustible: nueva tecnologia de gas natural para edificios energeticamente autoabastecidos

Energy Technology Data Exchange (ETDEWEB)

Gutierrez, A. M.

2000-07-01

Fuel Cells have emerged in the last decade as one of the most promising new and sustainable natural gas technologies for meeting the energy needs of all the economy sectors into the 21st century. Fuel Cells are an environmentally clean, quiet, and highly efficient method for generating electricity and heat from natural gas. A fuel cell is an electrochemical device that converts the chemical energy of a fuel directly to usable energy (electricity and heat) without combustion. For this reason, the application and use of the fuel cell technology may be the most important technological advancement of the next century. At the beginning of the 2000 year Sociedad de Gas de Euskadi, s. a. started a demonstration project in favour of the high-temperature planar solid oxide fuel cell (SOFC) for domestic micro-CHP utilization. This type is certainly most exacting from the materials standpoint, and it offers the advantage of uncomplicated fuel pretreatment. (Author)

Electrolytes for magnesium electrochemical cells

Science.gov (United States)

Burrell, Anthony K.; Sa, Niya; Proffit, Danielle Lee; Lipson, Albert; Liao, Chen; Vaughey, John T.; Ingram, Brian J.

2017-07-04

An electrochemical cell includes a high voltage cathode configured to operate at 1.5 volts or greater; an anode including Mg.sup.0; and an electrolyte including an ether solvent and a magnesium salt; wherein: a concentration of the magnesium salt in the ether is 1 M or greater.

Effect of cAMP derivates on assembly and maintenance of tight junctions in human umbilical vein endothelial cells

Directory of Open Access Journals (Sweden)

Beese Michaela

2010-09-01

Full Text Available Abstract Background Endothelial tight and adherens junctions control a variety of physiological processes like adhesion, paracellular transport of solutes or trafficking of activated leukocytes. Formation and maintenance of endothelial junctions largely depend on the microenvironment of the specific vascular bed and on interactions of the endothelium with adjacent cell types. Consequently, primary cultures of endothelial cells often lose their specific junctional pattern and fail to establish tight monolayer in vitro. This is also true for endothelial cells isolated from the vein of human umbilical cords (HUVEC which are widely used as model for endothelial cell-related studies. Results We here compared the effect of cyclic 3'-5'-adenosine monophosphate (cAMP and its derivates on formation and stabilization of tight junctions and on alterations in paracellular permeability in HUVEC. We demonstrated by light and confocal laser microscopy that for shorter time periods the sodium salt of 8-bromoadenosine-cAMP (8-Br-cAMP/Na and for longer incubation periods 8-(4-chlorophenylthio-cAMP (pCPT-cAMP exerted the greatest effects of all compounds tested here on formation of continuous tight junction strands in HUVEC. We further demonstrated that although all compounds induced protein kinase A-dependent expression of the tight junction proteins claudin-5 and occludin only pCPT-cAMP slightly enhanced paracellular barrier functions. Moreover, we showed that pCPT-cAMP and 8-Br-cAMP/Na induced expression and membrane translocation of tricellulin. Conclusions pCPT-cAMP and, to a lesser extend, 8-Br-cAMP/Na improved formation of continuous tight junction strands and decreased paracellular permeability in primary HUVEC. We concluded that under these conditions HUVEC represent a feasible in vitro model to study formation and disassembly of endothelial tight junctions and to characterize tight junction-associated proteins

Textbook Error: Short Circuiting on Electrochemical Cell

Science.gov (United States)

Bonicamp, Judith M.; Clark, Roy W.

2007-01-01

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

Electrochemical Methods for Reprocessing Defective Fuel Elements and for Decontaminating Equipment

International Nuclear Information System (INIS)

Mikheykin, S. V.; Rybakov, K. A.; Simonov, V. P.

2002-01-01

Reprocessing of fuel elements receives much consideration in nuclear engineering. Chemical and electrochemical methods are used for the purpose. For difficultly soluble materials based on zirconium alloys chemical methods are not suitable. Chemical reprocessing of defective or irradiated fuel elements requires special methods for their decladding because the dissolution of the clad material in nitric acid is either impossible (stainless steel, Zr alloys) or quite slow (aluminium). Fuel elements are cut in air-tight glove-boxes equipped with a dust collector and a feeder for crushed material. Chemical treatment is not free from limitations. For this reason we started a study of the feasibility of electrochemical methods for reprocessing defective and irradiated fuel elements. A simplified electrochemical technology developed makes it possible to recover expensive materials which were earlier wasted or required multi-step treatment. The method and an electrochemical cell are suitable for essentially complete dissolution of any fuel elements, specifically those made of materials which are difficultly soluble by chemical methods

Gas-permeable hydrophobic tubular membranes for ammonia recovery in bio-electrochemical systems

NARCIS (Netherlands)

Kuntke, P.; Zamora, P.; Saakes, M.; Buisman, C.J.N.; Hamelers, H.V.M.

2016-01-01

The application of a gas-permeable hydrophobic tubular membrane in bio-electrochemical systems enables efficient recovery of ammonia (NH₃) from their cathode compartments. Due to a hydrogen evolution reaction at the cathode, no chemical addition was required to increase the pH for

Regulation of Tight Junctions in Upper Airway Epithelium

Directory of Open Access Journals (Sweden)

Takashi Kojima

2013-01-01

Full Text Available The mucosal barrier of the upper respiratory tract including the nasal cavity, which is the first site of exposure to inhaled antigens, plays an important role in host defense in terms of innate immunity and is regulated in large part by tight junctions of epithelial cells. Tight junction molecules are expressed in both M cells and dendritic cells as well as epithelial cells of upper airway. Various antigens are sampled, transported, and released to lymphocytes through the cells in nasal mucosa while they maintain the integrity of the barrier. Expression of tight junction molecules and the barrier function in normal human nasal epithelial cells (HNECs are affected by various stimuli including growth factor, TLR ligand, and cytokine. In addition, epithelial-derived thymic stromal lymphopoietin (TSLP, which is a master switch for allergic inflammatory diseases including allergic rhinitis, enhances the barrier function together with an increase of tight junction molecules in HNECs. Furthermore, respiratory syncytial virus infection in HNECs in vitro induces expression of tight junction molecules and the barrier function together with proinflammatory cytokine release. This paper summarizes the recent progress in our understanding of the regulation of tight junctions in the upper airway epithelium under normal, allergic, and RSV-infected conditions.

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

Science.gov (United States)

Jiang, Rongzhong

2007-07-01

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.

Synthesis and characterization of electrochemically-reduced graphene

Indian Academy of Sciences (India)

Keywords. Graphene; electrochemical deposition; heat treatment; conductivity. 1. Introduction ... solar cells (Wu et al 2008; Sima et al 2011), molecular gas sensors ... solved in deionized (DI) water to obtain 0·01 M of electrolyte solution (Su et ...

Fabrication of Electrochemically Reduced Graphene Oxide Modified Gas Diffusion Electrode for In-situ Electrochemical Advanced Oxidation Process under Mild Conditions

International Nuclear Information System (INIS)

Dong, Heng; Su, Huimin; Chen, Ze; Yu, Han; Yu, Hongbing

2016-01-01

With aim to develop an efficient heterogeneous metal-free cathodic electrochemical advance oxidation process (CEAOP) for persistent organic pollutants (POPs) removal from wastewater under mild conditions, electrochemically reduced graphene oxide (ERGO)-modified gas diffusion electrode (GDE) was prepared for oxygen-containing radicals production via electrochemical oxygen reduction reaction (ORR). A detailed physical characterization was carried out by SEM, Raman spectroscopy, XRD and XPS. The electrocatalytic behavior for ORR was investigated by electrochemical measurements and electrolysis experiments under constant current density. Bisphenol A (BPA) of 20 mg L −1 was used as a model of POPs to evaluate the performance of the CEAOP with ERGO-modified GDE. The results showed that the defects concentration and electrochemical active sites of the ERGO was increased as the reduction time (30 min, 60 min and 120 min), leading to different catalysis on ORR. ·O 2 generation via one-electron ORR was found under the electrocatalysis of ERGO (60 min and 120 min), contributing to a complete degradation of BPA within 20 min and a mineralization current efficiency (MCE) of 74.60%. An alternative metal-free CEAOP independent of Fenton reaction was established based on ERGO-modified GDE for POPs removal from wastewater under mild conditions.

Hydrogen generation from natural gas for the fuel cell systems of tomorrow

Science.gov (United States)

Dicks, Andrew L.

In most cases hydrogen is the preferred fuel for use in the present generation of fuel cells being developed for commercial applications. Of all the potential sources of hydrogen, natural gas offers many advantages. It is widely available, clean, and can be converted to hydrogen relatively easily. When catalytic steam reforming is used to generate hydrogen from natural gas, it is essential that sulfur compounds in the natural gas are removed upstream of the reformer and various types of desulfurisation processes are available. In addition, the quality of fuel required for each type of fuel cell varies according to the anode material used, and the cell temperature. Low temperature cells will not tolerate high concentrations of carbon monoxide, whereas the molten fuel cell (MCFC) and solid oxide fuel cell (SOFC) anodes contain nickel on which it is possible to electrochemically oxidise carbon monoxide directly. The ability to internally reform fuel gas is a feature of the MCFC and SOFC. Internal reforming can give benefits in terms of increased electrical efficiency owing to the reduction in the required cell cooling and therefore parasitic system losses. Direct electrocatalysis of hydrocarbon oxidation has been the elusive goal of fuel cell developers over many years and recent laboratory results are encouraging. This paper reviews the principal methods of converting natural gas into hydrogen, namely catalytic steam reforming, autothermic reforming, pyrolysis and partial oxidation; it reviews currently available purification techniques and discusses some recent advances in internal reforming and the direct use of natural gas in fuel cells.

Disintegration of graphite matrix from the simulative high temperature gas-cooled reactor fuel element by electrochemical method

International Nuclear Information System (INIS)

Tian Lifang; Wen Mingfen; Li Linyan; Chen Jing

2009-01-01

Electrochemical method with salt as electrolyte has been studied to disintegrate the graphite matrix from the simulative high temperature gas-cooled reactor fuel elements. Ammonium nitrate was experimentally chosen as the appropriate electrolyte. The volume average diameter of disintegrated graphite fragments is about 100 μm and the maximal value is less than 900 μm. After disintegration, the weight of graphite is found to increase by about 20% without the release of a large amount of CO 2 probably owing to the partial oxidation to graphite in electrochemical process. The present work indicates that the improved electrochemical method has the potential to reduce the secondary nuclear waste and is a promising option to disintegrate graphite matrix from high temperature gas-cooled reactor spent fuel elements in the head-end of reprocessing.

Naturally fractured tight gas: Gas reservoir detection optimization. Quarterly report, January 1--March 31, 1997

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-12-31

Economically viable natural gas production from the low permeability Mesaverde Formation in the Piceance Basin, Colorado requires the presence of an intense set of open natural fractures. Establishing the regional presence and specific location of such natural fractures is the highest priority exploration goal in the Piceance and other western US tight, gas-centered basins. Recently, Advanced Resources International, Inc. (ARI) completed a field program at Rulison Field, Piceance Basin, to test and demonstrate the use of advanced seismic methods to locate and characterize natural fractures. This project began with a comprehensive review of the tectonic history, state of stress and fracture genesis of the basin. A high resolution aeromagnetic survey, interpreted satellite and SLAR imagery, and 400 line miles of 2-D seismic provided the foundation for the structural interpretation. The central feature of the program was the 4.5 square mile multi-azimuth 3-D seismic P-wave survey to locate natural fracture anomalies. The interpreted seismic attributes are being tested against a control data set of 27 wells. Additional wells are currently being drilled at Rulison, on close 40 acre spacings, to establish the productivity from the seismically observed fracture anomalies. A similar regional prospecting and seismic program is being considered for another part of the basin. The preliminary results indicate that detailed mapping of fault geometries and use of azimuthally defined seismic attributes exhibit close correlation with high productivity gas wells. The performance of the ten new wells, being drilled in the seismic grid in late 1996 and early 1997, will help demonstrate the reliability of this natural fracture detection and mapping technology.

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

International Nuclear Information System (INIS)

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

2011-01-01

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 µm 2 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

Dioscorin protects tight junction protein expression in A549 human airway epithelium cells from dust mite damage.

Science.gov (United States)

Fu, Lin Shien; Ko, Ying Hsien; Lin, Kuo Wei; Hsu, Jeng Yuan; Chu, Jao Jia; Chi, Chin Shiang

2009-12-01

In addition to being an allergen, the trypsin activity of dust mite extract also destroys the tight junctions of bronchial epithelium. Such damage can lead to airway leakage, which increases airway exposure to allergens, irritants, and other pathogens. Dioscorin, the storage protein of yam, demonstrates anti-trypsin activity, as well as other potential anti-inflammatory effects. This study investigated the protective role of dioscorin for tight junctions. The immunofluorescence stains of zonula occludens (ZO-1), E-cadherin (EC) and desmoplakin (DP) proteins were compared. A cultured A549 cell line was used as a control and A549 cells were incubated with mite extract 100 mg/mL for 16 h, with or without dioscorin 100 mg/mL pretreatment for 8 h and with dioscorin 100 mg/mL alone for 16 h. Western blot was performed to detect changes in ZO-1, EC, and DP in the treated A549 cell lines. Loss of tight junction protein expression (ZO-1, EC, DP) was demonstrated after 16-h mite extract incubation. The defect could be restored if cells were pretreated with dioscorin for 8 h. In addition, dioscorin did not cause damage to the A549 cell lines in terms of cell survival or morphology. Western blot showed no change in the amount of tight junction protein under various conditions. Dioscorin is a potential protector of airway damage caused by mite extract.

miR-Let7A Controls the Cell Death and Tight Junction Density of Brain Endothelial Cells under High Glucose Condition.

Science.gov (United States)

Song, Juhyun; Yoon, So Ra; Kim, Oh Yoen

2017-01-01

Hyperglycemia-induced stress in the brain of patients with diabetes triggers the disruption of blood-brain barrier (BBB), leading to diverse neurological diseases including stroke and dementia. Recently, the role of microRNA becomes an interest in the research for deciphering the mechanism of brain endothelial cell damage under hyperglycemia. Therefore, we investigated whether mircoRNA Let7A (miR-Let7A) controls the damage of brain endothelial (bEnd.3) cells against high glucose condition. Cell viability, cell death marker expressions (p-53, Bax, and cleaved poly ADP-ribose polymerase), the loss of tight junction proteins (ZO-1 and claudin-5), proinflammatory response (interleukin-6, tumor necrosis factor- α ), inducible nitric oxide synthase, and nitrite production were confirmed using MTT, reverse transcription-PCR, quantitative-PCR, Western blotting, immunofluorescence, and Griess reagent assay. miR-Let7A overexpression significantly prevented cell death and loss of tight junction proteins and attenuated proinflammatory response and nitrite production in the bEnd.3 cells under high glucose condition. Taken together, we suggest that miR-Let7A may attenuate brain endothelial cell damage by controlling cell death signaling, loss of tight junction proteins, and proinflammatory response against high glucose stress. In the future, the manipulation of miR-Let7A may be a novel solution in controlling BBB disruption which leads to the central nervous system diseases.

Transformation of a beta gamma hot-cell under air in a tight hot-cell under inert gas

International Nuclear Information System (INIS)

Lambert, G.

1981-05-01

For several years now, fuel elements from graphite gas reactors have been stored in pools at the Cadarache Center after having been subjected (in general) to laboratory examinations. The CEA has adopted the following re-transfer procedure for these fuel elements while awaiting reprocessing: the fuel elements are extracted from their existing cartridges and transferred into new welded stainless steel containers capable of assuring long term storage. The storage, however, envisaged is temporary and is realized in the Pegase pool, specially adapted for this purpose. This re-transfer operation is envisaged for some 2.300 containers. All the appropriate safety measures will be taken. The various different fuel materials handled are often highly irradiated. The presence of water in certain containers due to loss of leaktightness has led to a series of chemical reactions (corrosion of uranium by water, reactions with magnesium, formation of hydrides). As a result, existing envelopes can contain UO 2 , UH 3 and hydrogen; operations must therefore being carried out in an inert atmosphere (preferably argon). The re-transfer process can not therefore be carried out in a conventional cell. It is therefore envisaged to carry out this work in a leaktight cell in an inert atmosphere. A laboratory cell could be modified to perform these functions. This cell would be reconverted to its original state when operations terminate (in about 3 years time) [fr

SENP3 grants tight junction integrity and cytoskeleton architecture in mouse Sertoli cells.

Science.gov (United States)

Wu, Di; Huang, Chun-Jie; Khan, Faheem Ahmed; Jiao, Xiao-Fei; Liu, Xiao-Ming; Pandupuspitasari, Nuruliarizki Shinta; Brohi, Rahim Dad; Huo, Li-Jun

2017-08-29

Germ cells develop in a sophisticated immune privileged microenvironment provided by specialized junctions contiguous the basement membrane of the adjacent Sertoli cells that constituted the blood-testis barrier (BTB) in seminiferous epithelium of testis in mammals. Deciphering the molecular regulatory machinery of BTB activity is central to improve male fertility and the role of post-translational modification including SUMOylation pathway is one of the key factors. Herein, we unveiled the mystery of the SUMO-2/3 specific protease SENP3 (Sentrin-specific protease 3) in BTB dynamics regulation. SENP3 is predominantly expressed in the nucleus of Sertoli and spermatocyte cells in adult mouse testis, and knockdown of SENP3 compromises tight junction in Sertoli cells by destructing the permeability function with a concomitant decline in trans-epithelial electrical resistance in primary Sertoli cells, which could attribute to the conspicuous dysfunction of tight junction (TJ) proteins (e.g., ZO-1, occludin) at the cell-cell interface due to the inactivation of STAT3. Moreover, SENP3 knockdown disrupts F-actin architecture in Sertoli cells through intervening Rac1/CDC42-N-WASP-Arp2/3 signaling pathway and Profilin-1 abundance. Our study pinpoints SENP3 might be a novel determinant of multiple pathways governing BTB dynamics in testis to support germ cells development in mammals.

Appraisal of the tight sands potential of the Sand Wash and Great Divide Basins

International Nuclear Information System (INIS)

1993-08-01

The volume of future tight gas reserve additions is difficult to estimate because of uncertainties in the characterization and extent of the resource and the performance and cost-effectiveness of stimulation and production technologies. Ongoing R ampersand D by industry and government aims to reduce the risks and costs of producing these tight resources, increase the certainty of knowledge of their geologic characteristics and extent, and increase the efficiency of production technologies. Some basins expected to contain large volumes of tight gas are being evaluated as to their potential contribution to domestic gas supplies. This report describes the results of one such appraisal. This analysis addresses the tight portions of the Eastern Greater Green River Basin (Sand Wash and Great Divide Subbasins in Northwestern Colorado and Southwestern Wyoming, respectively), with respect to estimated gas-in-place, technical recovery, and potential reserves. Geological data were compiled from public and proprietary sources. The study estimated gas-in-place in significant (greater than 10 feet net sand thickness) tight sand intervals for six distinct vertical and 21 areal units of analysis. These units of analysis represent tight gas potential outside current areas of development. For each unit of analysis, a ''typical'' well was modeled to represent the costs, recovery and economics of near-term drilling prospects in that unit. Technically recoverable gas was calculated using reservoir properties and assumptions about current formation evaluation and extraction technology performance. Basin-specific capital and operating costs were incorporated along with taxes, royalties and current regulations to estimate the minimum required wellhead gas price required to make the typical well in each of unit of analysis economic

Coherent soft X-ray high-order harmonics using tight-focusing laser pulses in the gas mixture.

Science.gov (United States)

Lu, Faming; Xia, Yuanqin; Zhang, Sheng; Chen, Deying; Zhao, Yang; Liu, Bin

2014-01-01

We experimentally study the harmonics from a Xe-He gas mixture using tight-focusing femtosecond laser pulses. The spectrum in the mixed gases exhibits an extended cutoff region from the harmonic H21 to H27. The potential explanation is that the harmonics photons from Xe contribute the electrons of He atoms to transmit into the excited-state. Therefore, the harmonics are emitted from He atoms easily. Furthermore, we show that there are the suppressed harmonics H15 and H17 in the mixed gases. The underlying mechanism is the destructive interference between harmonics generated from different atoms. Our results indicate that HHG from Xe-He gas mixture is an efficient method of obtaining the coherent soft X-ray source.

Pulsed Electrochemical Mass Spectrometry for Operando Tracking of Interfacial Processes in Small-Time-Constant Electrochemical Devices such as Supercapacitors.

Science.gov (United States)

Batisse, Nicolas; Raymundo-Piñero, Encarnación

2017-11-29

A more detailed understanding of the electrode/electrolyte interface degradation during the charging cycle in supercapacitors is of great interest for exploring the voltage stability range and therefore the extractable energy. The evaluation of the gas evolution during the charging, discharging, and aging processes is a powerful tool toward determining the stability and energy capacity of supercapacitors. Here, we attempt to fit the gas analysis resolution to the time response of a low-gas-generation power device by adopting a modified pulsed electrochemical mass spectrometry (PEMS) method. The pertinence of the method is shown using a symmetric carbon/carbon supercapacitor operating in different aqueous electrolytes. The differences observed in the gas levels and compositions as a function of the cell voltage correlate to the evolution of the physicochemical characteristics of the carbon electrodes and to the electrochemical performance, giving a complete picture of the processes taking place at the electrode/electrolyte interface.

Microbial Electrolysis Cells for High Yield Hydrogen Gas Production from Organic Matter

KAUST Repository

Logan, Bruce E.

2008-12-01

The use of electrochemically active bacteria to break down organic matter, combined with the addition of a small voltage (>0.2 V in practice) in specially designed microbial electrolysis cells (MECs), can result in a high yield of hydrogen gas. While microbial electrolysis was invented only a few years ago, rapid developments have led to hydrogen yields approaching 100%, energy yields based on electrical energy input many times greater than that possible by water electrolysis, and increased gas production rates. MECs used to make hydrogen gas are similar in design to microbial fuel cells (MFCs) that produce electricity, but there are important differences in architecture and analytical methods used to evaluate performance. We review here the materials, architectures, performance, and energy efficiencies of these MEC systems that show promise as a method for renewable and sustainable energy production, and wastewater treatment. © 2008 American Chemical Society.

Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface groundwater: Background, base cases, shallow reservoirs, short-term gas, and water transport

Science.gov (United States)

Reagan, Matthew T; Moridis, George J; Keen, Noel D; Johnson, Jeffrey N

2015-01-01

Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on two general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes. Key Points: Short-term leakage fractured reservoirs requires high-permeability pathways Production strategy affects the likelihood and magnitude of gas release Gas release is likely short-term, without additional driving forces PMID

Effects of N2 mixed gas atomization on electrochemical properties of Mm(Ni,Co,Mn,Al)5.0 alloy powder

International Nuclear Information System (INIS)

Yanagimoto, K.; Sunada, S.; Majima, K.; Sawada, T.

2004-01-01

N 2 gas, N 2 -Ar mixed gas and Ar gas atomization followed by acid surface treatment was applied to improve electrochemical properties of AB 5 type hydrogen storage alloy powder. The shape of Ar atomized powder was spherical and it changed to be irregular with increasing N 2 content of mixed gas. Irrespective of gas kinds, electrodes of atomized powder showed the same discharge capacity as cast-pulverized powder under auxiliary electrical conductivity by nickel powder addition. Without nickel powder, however, N 2 atomized powder showed the best electrochemical properties as well as gas activation behavior. By the combination process of N 2 gas atomization and acid surface treatment, it was considered that irregular shape of N 2 atomized powder promoted electrical conductivity of electrodes and catalytic nickel concentrated surface layer was formed to increase the hydrogen storage rapidity

Emerging electrochemical energy conversion and storage technologies

Science.gov (United States)

Badwal, Sukhvinder P. S.; Giddey, Sarbjit S.; Munnings, Christopher; Bhatt, Anand I.; Hollenkamp, Anthony F.

2014-01-01

Electrochemical cells and systems play a key role in a wide range of industry sectors. These devices are critical enabling technologies for renewable energy; energy management, conservation, and storage; pollution control/monitoring; and greenhouse gas reduction. A large number of electrochemical energy technologies have been developed in the past. These systems continue to be optimized in terms of cost, life time, and performance, leading to their continued expansion into existing and emerging market sectors. The more established technologies such as deep-cycle batteries and sensors are being joined by emerging technologies such as fuel cells, large format lithium-ion batteries, electrochemical reactors; ion transport membranes and supercapacitors. This growing demand (multi billion dollars) for electrochemical energy systems along with the increasing maturity of a number of technologies is having a significant effect on the global research and development effort which is increasing in both in size and depth. A number of new technologies, which will have substantial impact on the environment and the way we produce and utilize energy, are under development. This paper presents an overview of several emerging electrochemical energy technologies along with a discussion some of the key technical challenges. PMID:25309898

Investigation of gas molecules adsorption on carbon nano tubes electric properties in tight binding model

International Nuclear Information System (INIS)

Moradian, R.; Mohammadi, Y.

2007-01-01

Based on tight binding model we investigated effects of bi-atomic molecules gas(in the general form denoted by X 2 )on single-walled carbon nano tubes electronic properties. We found for some specified values of hopping integrals and random on-site energies, adsorbed molecules bound states located inside of the (10,0) single-walled carbon nano tubes energy gap, where it is similar to the reported experimental results for O 2 adsorption while for other values there is no bound states inside of energy gap. This is similar to the N 2 adsorption on semiconductor single-walled carbon nano tubes.

Design of the ATLAS New Small Wheel Gas Leak Tightness Station for the Micromegas Detector Modules

CERN Document Server

Gazis, Evangelos; The ATLAS collaboration

2017-01-01

In this work we describe advanced data processing and analysis techniques intended to be used in the gas tightness station at CERN for Quality Assurance and Quality Control of the New Small Wheel Micromegas Quadruplets. We combine two methods: a conventional one based on the Pressure Decay Rate and an alternative-novel one, based on the Flow Rate Loss. A prototype setup has been developed based on a Lock-in Amplifier device and should be operated in conjunction with the gas leak test via the Flow Rate Loss. Both methods have been tested by using emulated leak branches based on specific thin medical needles. The semi-automatic data acquisition, monitoring and processing system is presented also in this work while a more sophisticated environment based on the WinCC-OA SCADA is under development.

Damage evaluation on oil-based drill-in fluids for ultra-deep fractured tight sandstone gas reservoirs

Directory of Open Access Journals (Sweden)

Jinzhi Zhu

2017-07-01

Full Text Available In order to explore the damage mechanisms and improve the method to evaluate and optimize the performance of formation damage control of oil-based drill-in fluids, this paper took an ultra-deep fractured tight gas reservoir in piedmont configuration, located in the Cretaceous Bashijiqike Fm of the Tarim Basin, as an example. First, evaluation experiments were conducted on the filtrate invasion, the dynamic damage of oil-based drill-in fluids and the loading capacity of filter cakes. Meanwhile, the evaluating methods were optimized for the formation damage control effect of oil-based drill-in fluids in laboratory: pre-processing drill-in fluids before grading analysis; using the dynamic damage method to simulate the damage process for evaluating the percentage of regained permeability; and evaluating the loading capacity of filter cakes. The experimental results show that (1 oil phase trapping damage and solid phase invasion are the main formation damage types; (2 the damage degree of filtrate is the strongest on the matrix; and (3 the dynamic damage degree of oil-based drill-in fluids reaches medium strong to strong on fractures and filter cakes show a good sealing capacity for the fractures less than 100 μm. In conclusion, the filter cakes' loading capacity should be first guaranteed, and both percentage of regained permeability and liquid trapping damage degree should be both considered in the oil-based drill-in fluids prepared for those ultra-deep fractured tight sandstone gas reservoirs.

Aging of electrochemical double layer capacitors with acetonitrile-based electrolyte at elevated voltages

International Nuclear Information System (INIS)

Ruch, P.W.; Cericola, D.; Foelske-Schmitz, A.; Koetz, R.; Wokaun, A.

2010-01-01

Laboratory-scale electrochemical capacitor cells with bound activated carbon electrodes and acetonitrile-based electrolyte were aged at various elevated constant cell voltages between 2.75 V and 4.0 V. During the constant voltage tests, the cell capacitance as well as the capacitance and resistance of each electrode was determined. Following each aging experiment, the cells were analyzed by means of electrochemical impedance spectroscopy, and the individual electrodes were characterized by gas adsorption and X-ray photoelectron spectroscopy. At cell voltages above 3.0 V, the positive electrode ages much faster than the negative. Both the capacitance loss and resistance increase of the cell could be totally attributed to the positive electrode. At cell voltages above 3.5 V also the negative electrode aged significantly. X-ray photoelectron spectroscopy indicated the presence of degradation products on the electrode surface with a much thicker layer on the positive electrode. Simultaneously, a significant decrease in electrode porosity could be detected by gas adsorption.

Effect of Gas Pressure on Polarization of SOFC Cathode Prepared by Plasma Spray

Science.gov (United States)

Li, Cheng-Xin; Wang, Zhun-Zhun; Liu, Shuai; Li, Chang-Jiu

2013-06-01

A cermet-supported tubular SOFC was fabricated using thermal spray. The cell performance was investigated at temperatures from 750 to 900 °C and pressures from 0.1 to 0.5 MPa to examine the effect of operating gas pressure on the cell performance. The influence of gas pressure on the cathodic polarization was studied through the electrochemical impedance approach to examine the controlling electrochemical processes during cell operation. Results show that increasing the operating gas pressure improves the power output performance significantly. When the gas pressure is increased from 0.1 to 0.3 MPa, the maximum power density is increased by a factor of 32% at a temperature of 800 °C. The cathode polarization decreases significantly with the increase of the gas pressure. The electrochemical analysis shows that the main control processes of the cathode reaction are the oxygen species transfer at the three-phase boundary and oxygen diffusion on the surface or in the bulk of the cathode, which are enhanced with increasing gas pressure.

Electrochemical removal of nickel ions from industrial wastewater

NARCIS (Netherlands)

Njau, K.N.; Woude, van der M.E.; Visser, G.J.; Janssen, L.J.J.

2000-01-01

The electrochemical reduction of nickel ions in dilute industrial wastewater from a galvanic nickel plating plant was carried out on a three-dimensional electrode in a gas diffusion electrode packed bed electrode cell (GBC) and also on a rotating disc electrode. To explain the experimental results,

Method of constructing an improved electrochemical cell

Science.gov (United States)

Grimes, Patrick G.; Einstein, Harry

1984-10-09

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.

Minimizing electrode contamination in an electrochemical cell

Science.gov (United States)

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

2014-12-09

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

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

Science.gov (United States)

Mauzeroll, Janine; Bard, Allen J.

2004-01-01

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 in a menadione-containing solution, the export of the conjugate from the cells with time could be measured. Similar experiments were performed on immobilized yeast cell aggregates stressed by a menadione solution. From the export of the menadione-glutathione conjugate detected at a 1-μm-diameter electrode situated 10 μm from the cells, a flux of about 30,000 thiodione molecules per second per cell was extracted. Numerical simulations based on an explicit finite difference method further revealed that the observation of a constant efflux of thiodione from the cells suggested the rate was limited by the uptake of menadione and that the efflux through the glutathione-conjugate pump was at least an order of magnitude faster. PMID:15148374

Design and Implementation of Energized Fracture Treatment in Tight Gas Sands

Energy Technology Data Exchange (ETDEWEB)

Mukul Sharma; Kyle Friehauf

2009-12-31

, the minimum CO{sub 2} gas quality (volume % of gas) recommended is 30% for moderate differences between fracture and reservoir pressures (2900 psi reservoir, 5300 psi fracture). The minimum quality is reduced to 20% when the difference between pressures is larger, resulting in additional gas expansion in the invaded zone. Inlet fluid temperature, flow rate, and base viscosity did not have a large impact on fracture production. Finally, every stage of the fracturing treatment should be energized with a gas component to ensure high gas saturation in the invaded zone. A second, more general, sensitivity study was conducted. Simulations show that CO{sub 2} outperforms N{sub 2} as a fluid component because it has higher solubility in water at fracturing temperatures and pressures. In fact, all gas components with higher solubility in water will increase the fluid's ability to reduce damage in the invaded zone. Adding methanol to the fracturing solution can increase the solubility of CO{sub 2}. N{sub 2} should only be used if the gas leaks-off either during the creation of the fracture or during closure, resulting in gas going into the invaded zone. Experimental data is needed to determine if the gas phase leaks-off during the creation of the fracture. Simulations show that the bubbles in a fluid traveling across the face of a porous medium are not likely to attach to the surface of the rock, the filter cake, or penetrate far into the porous medium. In summary, this research has created the first compositional fracturing simulator, a useful tool to aid in energized fracture design. We have made several important and original conclusions about the best practices when using energized fluids in tight gas sands. The models and tools presented here may be used in the future to predict behavior of any multi-phase or multi-component fracturing fluid system.

Electrochemical cell structure and method of making the same

Science.gov (United States)

Schick, Louis Andrew; Libby, Cara Suzanne; Bowen, John Henry; Bourgeois, Richard Scott

2012-09-25

An electrochemical cell structure is provided which includes an anode, a cathode spaced apart from said anode, an electrolyte in ionic communication with each of said anode and said cathode and a nonconductive frame. The nonconductive frame includes at least two components that support each of said anode, said cathode and said electrolyte and define at least one flowpath for working fluids and for products of electrochemical reaction.

Solid oxide electrochemical reactor science.

Energy Technology Data Exchange (ETDEWEB)

Sullivan, Neal P. (Colorado School of Mines, Golden, CO); Stechel, Ellen Beth; Moyer, Connor J. (Colorado School of Mines, Golden, CO); Ambrosini, Andrea; Key, Robert J. (Colorado School of Mines, Golden, CO)

2010-09-01

Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful information to their continued development. This LDRD involved a collaboration between Sandia and the Colorado School of Mines (CSM) ins solid-oxide electrochemical reactors targeted at solid oxide electrolyzer cells (SOEC), which are the reverse of solid-oxide fuel cells (SOFC). SOECs complement Sandia's efforts in thermochemical production of alternative fuels. An SOEC technology would co-electrolyze carbon dioxide (CO{sub 2}) with steam at temperatures around 800 C to form synthesis gas (H{sub 2} and CO), which forms the building blocks for a petrochemical substitutes that can be used to power vehicles or in distributed energy platforms. The effort described here concentrates on research concerning catalytic chemistry, charge-transfer chemistry, and optimal cell-architecture. technical scope included computational modeling, materials development, and experimental evaluation. The project engaged the Colorado Fuel Cell Center at CSM through the support of a graduate student (Connor Moyer) at CSM and his advisors (Profs. Robert Kee and Neal Sullivan) in collaboration with Sandia.

Expression patterns of tight junction components induced by CD24 in an oral epithelial cell-culture model correlated to affected periodontal tissues.

Science.gov (United States)

Ye, P; Yu, H; Simonian, M; Hunter, N

2014-04-01

Previously we demonstrated uniformly strong expression of CD24 in the epithelial attachment to the tooth and in the migrating epithelium of the periodontitis lesion. Titers of serum antibodies autoreactive with CD24 peptide correlated with reduced severity of periodontal disease. Ligation of CD24 expressed by oral epithelial cells induced formation of tight junctions that limited paracellular diffusion. In this study, we aimed to reveal that the lack of uniform expression of tight junction components in the pocket epithelium of periodontitis lesions is likely to contribute to increased paracellular permeability to bacterial products. This is proposed as a potential driver of the immunopathology of periodontitis. An epithelial culture model with close correspondence for expression patterns for tight junction components in periodontal epithelia was used. Immunohistochemical staining and confocal laser scanning microscopy were used to analyse patterns of expression of gingival epithelial tight junction components. The minimally inflamed gingival attachment was characterized by uniformly strong staining at cell contacts for the tight junction components zona occludens-1, zona occludens-2, occludin, junction adhesion molecule-A, claudin-4 and claudin-15. In contrast, the pocket epithelium of the periodontal lesion showed scattered, uneven staining for these components. This pattern correlated closely with that of unstimulated oral epithelial cells in culture. Following ligation of CD24 expressed by these cells, the pattern of tight junction component expression of the minimally inflamed gingival attachment developed rapidly. There was evidence for non-uniform and focal expression only of tight junction components in the pocket epithelium. In the cell-culture model, ligation of CD24 induced a tight junction expression profile equivalent to that observed for the minimally inflamed gingival attachment. Ligation of CD24 expressed by gingival epithelial cells by lectin

Permeability, strength and electrochemical studies on ceramic multilayers for solid-state electrochemical cells

DEFF Research Database (Denmark)

Andersen, Kjeld Bøhm; Charlas, Benoit; Stamate, Eugen

2017-01-01

An electrochemical reactor can be used to purify flue gasses. Such a reactor can be a multilayer structure consisting of alternating layers of porous electrodes and electrolytes (a porous cell stack). In this work optimization of such a unit has been done by changing the pore former composition...

Calcium oxalate crystals induces tight junction disruption in distal renal tubular epithelial cells by activating ROS/Akt/p38 MAPK signaling pathway.

Science.gov (United States)

Yu, Lei; Gan, Xiuguo; Liu, Xukun; An, Ruihua

2017-11-01

Tight junction plays important roles in regulating paracellular transports and maintaining cell polarity. Calcium oxalate monohydrate (COM) crystals, the major crystalline composition of kidney stones, have been demonstrated to be able to cause tight junction disruption to accelerate renal cell injury. However, the cellular signaling involved in COM crystal-induced tight junction disruption remains largely to be investigated. In the present study, we proved that COM crystals induced tight junction disruption by activating ROS/Akt/p38 MAPK pathway. Treating Madin-Darby canine kidney (MDCK) cells with COM crystals induced a substantial increasing of ROS generation and activation of Akt that triggered subsequential activation of ASK1 and p38 mitogen-activated protein kinase (MAPK). Western blot revealed a significantly decreased expression of ZO-1 and occludin, two important structural proteins of tight junction. Besides, redistribution and dissociation of ZO-1 were observed by COM crystals treatment. Inhibition of ROS by N-acetyl-l-cysteine (NAC) attenuated the activation of Akt, ASK1, p38 MAPK, and down-regulation of ZO-1 and occludin. The redistribution and dissociation of ZO-1 were also alleviated by NAC treatment. These results indicated that ROS were involved in the regulation of tight junction disruption induced by COM crystals. In addition, the down-regulation of ZO-1 and occludin, the phosphorylation of ASK1 and p38 MAPK were also attenuated by MK-2206, an inhibitor of Akt kinase, implying Akt was involved in the disruption of tight junction upstream of p38 MAPK. Thus, these results suggested that ROS-Akt-p38 MAPK signaling pathway was activated in COM crystal-induced disruption of tight junction in MDCK cells.

A mathematical model of the current density distribution in electrochemical cells - AUTHORS’ REVIEW

Directory of Open Access Journals (Sweden)

PREDRAG M. ŽIVKOVIĆ

2011-06-01

Full Text Available An approach based on the equations of electrochemical kinetics for the estimation of the current density distribution in electrochemical cells is presented. This approach was employed for a theoretical explanation of the phenomena of the edge and corner effects. The effects of the geometry of the system, the kinetic parameters of the cathode reactions and the resistivity of the solution are also discussed. A procedure for a complete analysis of the current distribution in electrochemical cells is presented.

Characterization of Microbial Fuel Cells at Microbially and Electrochemically Meaningful Time scales

KAUST Repository

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

2011-01-01

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

Electrochemical cell assembled in discharged state

Science.gov (United States)

Yao, Neng-Ping; Walsh, William J.

1976-01-01

A secondary, electrochemical cell is assembled in a completely discharged state within a sealed containment. As assembled, the cell includes a positive electrode separated from a negative electrode by a molten salt electrolyte. The positive electrode is contained within a porous structure, permitting passage of molten electrolyte, and includes one or more layers of a metallic mesh, e.g. iron, impregnated with an intimate mixture of lithium sulfide and the electrolyte. The negative electrode is a porous plaque of aluminum metal. Prior to using the cell, an electrical charge forms lithium-aluminum alloy within the negative electrode and metal sulfide within the positive electrode.

Cell structure for electrochemical devices and method of making same

Science.gov (United States)

Kaun, Thomas D.

1993-01-01

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

Sodium caprate transiently opens claudin-5-containing barriers at tight junctions of epithelial and endothelial cells

DEFF Research Database (Denmark)

Del Vecchio, Giovanna; Tscheik, Christian; Tenz, Kareen

2012-01-01

Claudin-5 is a tight junction (TJ) protein which limits the diffusion of small hydrophilic molecules. Thus, it represents a potential pharmacological target to improve drug delivery to the tissues protected by claudin-5-dependent barriers. Sodium caprate is known as an absorption enhancer which...... opens the paracellular space acting on TJ proteins and actin cytoskeleton. Its action on claudin-5 is not understood so far. Epithelial and endothelial systems were used to evaluate the effect of caprate on claudin-5 in TJ-free cells and on claudin-5 fully integrated in TJ. To this aim, confocal...... of endothelial and epithelial cells. In conclusion, the study further elucidates the cellular effects of caprate at the tight junctions....

Electrode of solid state polymer electrolyte type electrochemical cell; Kobunshi kotai denkaisitsugata denki kagaku seru yo denkyo

Energy Technology Data Exchange (ETDEWEB)

Watanabe, M [Yamanashi, (Japan); Inoue, M [Tanaka Kikinzoku Kogyo, Tokyo (Japan)

1996-04-12

The solid state polymer electrolyte type electrochemical cell (PEMFC) has such problem that the gas diffusion from the resin surface to the catalyst surface is prevented when the coating thickness of cation exchange resin on the catalyst particle and the number of micropores which conduct the gas flow in the catalyst layer are reduced. Resultingly, a sufficiently large current cannot be taken out of the cell. This invention solves the problem. The catalyst layer of electrode of PEMFC consists of a mixture of the conductive catalyst carrier coated with cation exchange resin and the conductive carrier coated with fluorinated hydrocarbon polymer. Adding the water repellent material to the electrode in this way improves the air-passing porosity. As for the cation exchange resin, perfluorocarbon sulfonate or perfluorocarbon carboxylate can be used. For the fluorinated hydrocarbon polymer, fluorinated polyethylene is preferably used. 4 figs., 2 tabs.

Electrochemical power sources batteries, fuel cells, and supercapacitors

CERN Document Server

Bagotsky, Vladimir S; Volfkovich, Yurij M

2015-01-01

Electrochemical Power Sources (EPS) provides in a concise way theoperational features, major types, and applications of batteries,fuel cells, and supercapacitors Details the design, operational features, andapplications of batteries, fuel cells, and supercapacitors Covers improvements of existing EPSs and thedevelopment of new kinds of EPS as the results of intense R&Dwork Provides outlook for future trends in fuel cells andbatteries Covers the most typical battery types, fuel cells andsupercapacitors; such as zinc-carbon batteries, alkaline manganesedioxide batteries, mercury-zinc cells, lead

Degradation of graphene coated copper in simulated proton exchange membrane fuel cell environment: Electrochemical impedance spectroscopy study

Science.gov (United States)

Ren, Y. J.; Anisur, M. R.; Qiu, W.; He, J. J.; Al-Saadi, S.; Singh Raman, R. K.

2017-09-01

Metallic materials are most suitable for bipolar plates of proton exchange membrane fuel cell (PEMFC) because they possess the required mechanical strength, durability, gas impermeability, acceptable cost and are suitable for mass production. However, metallic bipolar plates are prone to corrosion or they can passivate under PEMFC environment and interrupt the fuel cell operation. Therefore, it is highly attractive to develop corrosion resistance coating that is also highly conductive. Graphene fits these criteria. Graphene coating is developed on copper by chemical vapor deposition (CVD) with an aim to improving corrosion resistance of copper under PEMFC condition. The Raman Spectroscopy shows the graphene coating to be multilayered. The electrochemical degradation of graphene coated copper is investigated by electrochemical impedance spectroscopy (EIS) in 0.5 M H2SO4 solution at room temperature. After exposure to the electrolyte for up to 720 h, the charge transfer resistance (Rt) of the graphene coated copper is ∼3 times greater than that of the bare copper, indicating graphene coatings could improve the corrosion resistance of copper bipolar plates.

Process for removal of hydrogen halides or halogens from incinerator gas

Science.gov (United States)

Huang, H.S.; Sather, N.F.

1987-08-21

A process for reducing the amount of halogens and halogen acids in high temperature combustion gas and through their removal, the formation of halogenated organics at lower temperatures, with the reduction being carried out electrochemically by contacting the combustion gas with the negative electrode of an electrochemical cell and with the halogen and/or halogen acid being recovered at the positive electrode.

Modified gas diffusion layer for fuel cells synthesized by pulsed laser ablation

International Nuclear Information System (INIS)

Ebrasu, Daniela; Stefanescu, Ioan; Dorcioman, Gabriela; Serban, Nicolae; Axente, Emil; Sima, Felix; Ristoscu, Carmen; Mihailescu, Ioan N.; Enculescu, Ionut

2010-01-01

Full text; In this paper there are presented the first results regarding the development of a modified gas diffusion layer for fuel cells consisting of a simple or teflonized carbon cloth deposited by pulsed laser with metal oxide nanostructures. These are designed to operate both as co-catalyst, and oxidic support for other electrochemically active catalysts. We selected TiO 2 , ZnO and Al 2 O 3 doped (2 wt.%) ZnO which were uniformly distributed over the surface of gas diffusion layers in order to improve the catalytic activity, stability and lifetime, and reduce the production costs of proton exchange membrane fuel cells. We evidenced by scanning electron microscopy and energy dispersive spectroscopy that our depositions consisted of TiO 2 nanoparticles while in the case of ZnO and Al 2 O 3 doped (2 wt.%) ZnO transparent quasicontinuous films were synthesized. (authors)

Characterization of a stirred tank electrochemical cell for water disinfection processes

International Nuclear Information System (INIS)

Polcaro, A.M.; Vacca, A.; Mascia, M.; Palmas, S.; Pompei, R.; Laconi, S.

2007-01-01

Laboratory experiments were performed to characterize the behaviour of an electrochemical cell equipped with boron-doped diamond anodes and to verify its effectiveness in water disinfection. The hydrodynamic regime was determined when the cell worked either in batch or in continuous mode. Galvanostatic electrolyses of aqueous 1 mM Na 2 SO 4 solutions were performed to investigate on the oxidant production in different experimental conditions. The same solutions contaminated by E. coli, enterococci and coliforms were used as test media to verify the effectiveness of the system in the disinfection process. Experimental results indicated that the major inactivation mechanism of bacteria in the electrochemical cell is a disinfection by electrochemically generated oxidants, however a cooperative effect of superficial reaction has to be taken into account. The great capability of BDD anode to produce reactive oxygen species (ROS) and other oxidizing species during the electrolysis allows to establish a chlorine-free disinfection process

Electrochemically Deposited Polypyrrole for Dye-Sensitized Solar Cell Counter Electrodes

Directory of Open Access Journals (Sweden)

Khamsone Keothongkham

2012-01-01

Full Text Available Polypyrrole films were coated on conductive glass by electrochemical deposition (alternative current or direct current process. They were then used as the dye-sensitized solar cell counter electrodes. Scanning electron microscopy revealed that polypyrrole forms a nanoparticle-like structure on the conductive glass. The amount of deposited polypyrrole (or film thickness increased with the deposition duration, and the performance of polypyrrole based-dye-sensitized solar cells is dependant upon polymer thickness. The highest efficiency of alternative current and direct current polypyrrole based-dye-sensitized solar cells (DSSCs is 4.72% and 4.02%, respectively. Electrochemical impedance spectroscopy suggests that the superior performance of alternative current polypyrrole solar cells is due to their lower charge-transfer resistance between counter electrode and electrolyte. The large charge-transfer resistance of direct current solar cells is attributed to the formation of unbounded polypyrrole chains minimizing the I3 − reduction rate.

Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells.

Science.gov (United States)

Sim, Junyoung; An, Junyeong; Elbeshbishy, Elsayed; Ryu, Hodon; Lee, Hyung-Sool

2015-11-01

Cathode potential and O2 supply methods were investigated to improve H2O2 synthesis in an electrochemical cell, and optimal cathode conditions were applied for microbial electrochemical cells (MECs). Using aqueous O2 for the cathode significantly improved current density, but H2O2 conversion efficiency was negligible at 0.3-12%. Current density decreased for passive O2 diffusion to the cathode, but H2O2 conversion efficiency increased by 65%. An MEC equipped with a gas diffusion cathode was operated with acetate medium and domestic wastewater, which presented relatively high H2O2 conversion efficiency from 36% to 47%, although cathode overpotential was fluctuated. Due to different current densities, the maximum H2O2 production rate was 141 mg H2O2/L-h in the MEC fed with acetate medium, but it became low at 6 mg H2O2/L-h in the MEC fed with the wastewater. Our study clearly indicates that improving anodic current density and mitigating membrane fouling would be key parameters for large-scale H2O2-MECs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Electrochemical testing of suspension plasma sprayed solid oxide fuel cell electrolytes

Science.gov (United States)

Waldbillig, D.; Kesler, O.

Electrochemical performance of metal-supported plasma sprayed (PS) solid oxide fuel cells (SOFCs) was tested for three nominal electrolyte thicknesses and three electrolyte fabrication conditions to determine the effects of electrolyte thickness and microstructure on open circuit voltage (OCV) and series resistance (R s). The measured OCV values were approximately 90% of the Nernst voltages, and electrolyte area specific resistances below 0.1 Ω cm 2 were obtained at 750 °C for electrolyte thicknesses below 20 μm. Least-squares fitting was used to estimate the contributions to R s of the YSZ bulk material, its microstructure, and the contact resistance between the current collectors and the cells. It was found that the 96% dense electrolyte layers produced from high plasma gas flow rate conditions had the lowest permeation rates, the highest OCV values, and the smallest electrolyte-related voltage losses. Optimal electrolyte thicknesses were determined for each electrolyte microstructure that would result in the lowest combination of OCV loss and voltage loss due to series resistance for operating voltages of 0.8 V and 0.7 V.

Electrochemical formation of a Pt/Zn alloy and its use as a catalyst for oxygen reduction reaction in fuel cells.

Science.gov (United States)

Sode, Aya; Li, Winton; Yang, Yanguo; Wong, Phillip C; Gyenge, Elod; Mitchell, Keith A R; Bizzotto, Dan

2006-05-04

The characterization of an electrochemically created Pt/Zn alloy by Auger electron spectroscopy is presented indicating the formation of the alloy, the oxidation of the alloy, and the room temperature diffusion of the Zn into the Pt regions. The Pt/Zn alloy is stable up to 1.2 V/RHE and can only be removed with the oxidation of the base Pt metal either electrochemically or in aqua regia. The Pt/Zn alloy was tested for its effectiveness toward oxygen reduction. Kinetics of the oxygen reduction reaction (ORR) were measured using a rotating disk electrode (RDE), and a 30 mV anodic shift in the potential of ORR was found when comparing the Pt/Zn alloy to Pt. The Tafel slope was slightly smaller than that measured for the pure Pt electrode. A simple procedure for electrochemically modifying a Pt-containing gas diffusion electrode (GDE) with Zn was developed. The Zn-treated GDE was pressed with an untreated GDE anode, and the created membrane electrode assembly was tested. Fuel cell testing under two operating conditions (similar anode and cathode inlet pressures, and a larger cathode inlet pressure) indicated that the 30 mV shift observed on the RDE was also evident in the fuel cell tests. The high stability of the Pt/Zn alloy in acidic environments has a potential benefit for fuel cell applications.

Two-dimensional simulation of gas concentration impedance for a planar solid oxide fuel cell

International Nuclear Information System (INIS)

Fadaei, M.; Mohammadi, R.; Ghassemi, M.

2014-01-01

Highlights: • The 2D simulation shows another feature in concentration impedance. • The channel gas transport causes a capacitive behavior. • Anode polarization variation has a significant influence on velocity distribution. • The influence of 2D simulation is important for channel height bigger than 2 mm. - Abstract: This paper presents a two-dimensional model for a planar solid oxide fuel cell (SOFC) anode in order to simulate the steady-state performance characteristics as well as the electrochemical impedance spectra. The developed model couples the mass transport with the electrochemical kinetics. The transient conservation equations (momentum and species equations) are solved numerically and the linear kinetic is used for the anode electrochemistry. In order to solve the system of the nonlinear equations, an in-house code based on the finite volume method is developed and utilized. A parametric study is also carried out and the results are discussed. Results show a capacitive semicircle in the Nyquist plot which is identical to the gas concentration impedance. The simulation results are in good agreement with published data

Investigation of gas flow characteristics in proton exchange membrane fuel cell

International Nuclear Information System (INIS)

Kwac, Lee Ku; Kim, Hong Gun

2008-01-01

An investigation of electrochemical behavior of PEMFC (proton exchange membrane fuel cell) is performed by using a single-phase two-dimensional finite element analysis. Equations of current balance, mass balance, and momentum balance are implemented to simulate the behavior of PEMFC. The analysis results for the co-flow and counterflow mode of gas flow direction are examined in detail in order to compare how the gas flow direction affects quantitatively. The characteristics of internal properties, such as gas velocity distribution, mass fraction of the reactants, fraction of water and current density distribution in PEMFC are illustrated in the electrode and GDL (gas diffusion layer). It is found that the dry reactant gases can be well internally humidified and maintain high performance in the case of the counter-flow mode without external humidification while it is not advantageous for highly humidified or saturated reactant gases. It is also found that the co-flow mode improves the current density distribution with humidified normal condition compared to the counter-flow mode

Capacitance-Assisted Sustainable Electrochemical Carbon Dioxide Mineralisation.

Science.gov (United States)

Lamb, Katie J; Dowsett, Mark R; Chatzipanagis, Konstantinos; Scullion, Zhan Wei; Kröger, Roland; Lee, James D; Aguiar, Pedro M; North, Michael; Parkin, Alison

2018-01-10

An electrochemical cell comprising a novel dual-component graphite and Earth-crust abundant metal anode, a hydrogen producing cathode and an aqueous sodium chloride electrolyte was constructed and used for carbon dioxide mineralisation. Under an atmosphere of 5 % carbon dioxide in nitrogen, the cell exhibited both capacitive and oxidative electrochemistry at the anode. The graphite acted as a supercapacitive reagent concentrator, pumping carbon dioxide into aqueous solution as hydrogen carbonate. Simultaneous oxidation of the anodic metal generated cations, which reacted with the hydrogen carbonate to give mineralised carbon dioxide. Whilst conventional electrochemical carbon dioxide reduction requires hydrogen, this cell generates hydrogen at the cathode. Carbon capture can be achieved in a highly sustainable manner using scrap metal within the anode, seawater as the electrolyte, an industrially relevant gas stream and a solar panel as an effective zero-carbon energy source. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Characterization of Microbial Fuel Cells at Microbially and Electrochemically Meaningful Time scales

KAUST Repository

Ren, Zhiyong

2011-03-15

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 singlechamber 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 Ω), while more diverse rod-shaped cells formed dense biofilms under lower resistances (10, 50, and 265 Ω). 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 ofMFCanode biofilm evolution with external resistance and electricity production offers several operational strategies for system optimization. © 2011 American Chemical Society.

Electrochemical sensors applied to pollution monitoring: Measurement error and gas ratio bias - A volcano plume case study

Science.gov (United States)

Roberts, T. J.; Saffell, J. R.; Oppenheimer, C.; Lurton, T.

2014-06-01

There is an increasing scientific interest in the use of miniature electrochemical sensors to detect and quantify atmospheric trace gases. This has led to the development of ‘Multi-Gas' systems applied to measurements of both volcanic gas emissions, and urban air pollution. However, such measurements are subject to uncertainties introduced by sensor response time, a critical issue that has received limited attention to date. Here, a detailed analysis of output from an electrochemical SO2 sensor and two H2S sensors (contrasting in their time responses and cross-sensitivities) demonstrates how instrument errors arise under the conditions of rapidly fluctuating (by dilution) gas abundances, leading to scatter and importantly bias in the reported gas ratios. In a case study at Miyakejima volcano (Japan), electrochemical sensors were deployed at both the crater-rim and downwind locations, thereby exposed to rapidly fluctuating and smoothly varying plume gas concentrations, respectively. Discrepancies in the H2S/SO2 gas mixing ratios derived from these measurements are attributed to the sensors' differing time responses to SO2 and H2S under fluctuating plume conditions, with errors magnified by the need to correct for SO2 interference in the H2S readings. Development of a sensor response model that reproduces sensor t90 behaviour (the time required to reach 90% of the final signal following a step change in gas abundance) during calibration enabled this measurement error to be simulated numerically. The sensor response times were characterised as SO2 sensor (t90 ~ 13 s), H2S sensor without interference (t90 ~ 11 s), and H2S sensor with interference (t90 ~ 20 s to H2S and ~ 32 s to SO2). We show that a method involving data integration between periods of episodic plume exposure identifiable in the sensor output yields a less biased H2S/SO2 ratio estimate than that derived from standard analysis approaches. For the Miyakejima crater-rim dataset this method yields highly

Characterising of solid state electrochemical cells under operation

DEFF Research Database (Denmark)

Holtappels, Peter

2014-01-01

Compared to significant progress in PEMFC especially regarding the utilization of complex fuels such as methanol significant progress has been made by applying spectroscopic / differential IR and spectrometric techniques to working fuel cells, the processes in solid state high temperature...... electrochemical cells are still a "black box". In order to identify local reaction sites, surface coverage and potential/current introduced materials and surface modifications, in situ techniques are needed to gain a better understanding of the elementary and performance limiting steps for these cells...

Electrochemical energy generation

International Nuclear Information System (INIS)

Kreysa, G.; Juettner, K.

1993-01-01

The proceedings encompass 40 conference papers belonging to the following subject areas: Baseline and review papers; electrochemical fuel cells; batteries: Primary and secondary cells; electrochemical, regenerative systems for energy conversion; electrochemical hydrogen generation; electrochemistry for nuclear power plant; electrochemistry for spent nuclear fuel reprocessing; energy efficiency in electrochemical processes. There is an annex listing the authors and titles of the poster session, and compacts of the posters can be obtained from the office of the Gesellschaft Deutscher Chemiker, Abteilung Tagungen. (MM) [de

Effects of adenine nucleotide and sterol depletion on tight junction structure and function in MDCK cells

International Nuclear Information System (INIS)

Ladino, C.A.

1988-01-01

The antitumor agent Hadacidin (H), N-formyl-hydroxyamino-acetic acid, reversibly inhibited the multiplication of clone 4 Madin-Darby canine kidney (MDCK) cells at a 4 mM concentration within 24-48 hours. Treated cells were arrested in the S phase of the cell cycle. Accompanying this action was a 16-fold increase in the area occupied b the cells and a refractoriness to trypsin treatment. To test whether this effect was due to an increase in tight junction integrity, electrical resistance (TER) was measured across H-treated monolayers. Addition of H at the onset of junction formation reversibly prevented the development of TER. ATP and cAMP levels were decreased by H, as well as the rate of [ 3 H]-leucine incorporation into protein. When 1 mM dibutyryl-cAMP (d.cAMP) and theophylline were added, H had no effect on cell division or protein synthesis, and TER was partially restored. The addition of 1 mM d.cAMP and 1 mM theophylline to control cultures decreased TER, indicating a biphasic effect on TER development/maintenance. In a separate study, the effect of sterol depletion on tight junctions formation/maintenance in wild-type MDCK cells was investigated

Preparation of three-dimensional nitrogen-doped graphene layers by gas foaming method and its electrochemical capactive behavior

International Nuclear Information System (INIS)

Hao, Junnan; Shu, Dong; Guo, Songtao; Gao, Aimei; He, Chun; Zhong, Yayun; Liao, Yuqing; Huang, Yulan; Zhong, Jie

2016-01-01

Highlights: • A three-dimensional porous graphene layers was prepared via a gas foaming method. • Melamine was the nitrogen source to synthesize the N-doped 3D graphene layers. • The specific surface area of 3D N-doped graphene material is as high as 1196 m 2 g −1 . • The 3D N-doped graphene specific capacitance is 335 F g −1 in three-electrode system. • The energy density of 3D N-doped graphene reaches 58.1 Wh kg −1 in a symmetric cell. - Abstract: A porous graphene layers with a three-dimensional structure (3DG) was prepared via a gas foaming method based on a polymeric predecessor. This intimately interconnected 3DG structure not only significantly increases the specific surface area but also provides more channels to facilitate electron transport. In addition, 3D N-doped (3DNG) layers materials were synthesized using melamine as a nitrogen source. The nitrogen content in the 3DNG layers significantly influenced the electrochemical performance. The sample denoted as 3DNG-2 exhibited a specific capacitance of 335.2 F g −1 at a current density of 1 A g −1 in a three-electrode system. Additionally, 3DNG-2 exhibited excellent electrochemical performance in aqueous and organic electrolytes using a two-electrode symmetric cell. An energy density of 58.1 Wh kg −1 at a power density of 2500 W kg −1 was achieved, which is approximately 3 times that (19.6 Wh kg −1 ) in an aqueous electrolyte in a two-electrode system. After 1000 cycles, the capacity retention in aqueous electrolyte was more than 99.0%, and this retention in organic electrolytes was more than 89.4%, which demonstrated its excellent cycle stability. This performance makes 3DNG-2 a promising candidate as an electrode material in high-power and high-energy supercapacitor applications.

Electrochemical cell and method of assembly

Science.gov (United States)

Shimotake, Hiroshi; Voss, Ernst C. H.; Bartholme, Louis G.

1979-01-01

A method of preparing an electrochemical cell is disclosed which permits the assembly to be accomplished in air. The cell includes a metal sulfide as the positive electrode reactant, lithium alloy as the negative electrode reactant and an alkali metal, molten salt electrolyte. Positive electrode reactant is introduced as Li.sub.2 FeS.sub.2, a single-phase compound produced by the reaction of Li.sub.2 S and FeS. The use of this compound permits introduction of lithium in an oxidized form. Additional lithium can be introduced in the negative electrode structure enclosed within an aluminum foil envelope between layers of porous aluminum. Molten salt electrolyte is added after assembly and evacuation of the cell by including an interelectrode separator that has been prewet with an organic solution of KCl.

Electrochemical protein cleavage in a microfluidic cell with integrated boron doped diamond electrodes

NARCIS (Netherlands)

van den Brink, Floris Teunis Gerardus; Zhang, Tao; Ma, Liwei; Odijk, Mathieu; Olthuis, Wouter; Permentier, Hjalmar P.; Bischoff, Rainer P.H.; van den Berg, Albert

2015-01-01

We present a microfluidic electrochemical cell with integrated boron doped diamond (BDD) electrodes which is designed for high electrochemical conversion efficiencies. With our newest developments, we aim to exploit the benefits of BDD as a novel electrode material to conduct tyrosine- and

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

Energy Technology Data Exchange (ETDEWEB)

Thiangkaew, Anongnad; Keothongkham, Khamsone; Maiaugree, Wasan; Jarernboon, Wirat [Khon Kaen University, Khon Kaen (Thailand); Kamwanna, Teerasak; Pimanpang, Samuk; Amornkitbamrung, Vittaya [Khon Kaen University, Khon Kaen (Thailand); Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen (Thailand)

2014-05-15

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 film's 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.

In situ electrochemical high-energy X-ray diffraction using a capillary working electrode cell geometry

Energy Technology Data Exchange (ETDEWEB)

Young, Matthias J.; Bedford, Nicholas M.; Jiang, Naisheng; Lin, Deqing; Dai, Liming

2017-05-26

The ability to generate new electrochemically active materials for energy generation and storage with improved properties will likely be derived from an understanding of atomic-scale structure/function relationships during electrochemical events. Here, the design and implementation of a new capillary electrochemical cell designed specifically forin situhigh-energy X-ray diffraction measurements is described. By increasing the amount of electrochemically active material in the X-ray path while implementing low-Zcell materials with anisotropic scattering profiles, an order of magnitude enhancement in diffracted X-ray signal over traditional cell geometries for multiple electrochemically active materials is demonstrated. This signal improvement is crucial for high-energy X-ray diffraction measurements and subsequent Fourier transformation into atomic pair distribution functions for atomic-scale structural analysis. As an example, clear structural changes in LiCoO₂under reductive and oxidative conditions using the capillary cell are demonstrated, which agree with prior studies. Accurate modeling of the LiCoO₂diffraction data using reverse Monte Carlo simulations further verifies accurate background subtraction and strong signal from the electrochemically active material, enabled by the capillary working electrode geometry.

Characterization and optimization of cathodic conditions for H2O2 synthesis in microbial electrochemical cells

Science.gov (United States)

Cathode potential and O2 supply methods were investigated to improve H2O2 synthesis in an electrochemical cell, and optimal cathode conditions were applied for microbial electrochemical cells (MECs). Using aqueous O2 for the cathode significantly improved current density, but H2...

Expression of Tight Junction Protein Claudin-1 in Human Crescentic Glomerulonephritis

Directory of Open Access Journals (Sweden)

Ryo Koda

2014-01-01

Full Text Available The origin of crescent forming cells in human glomerulonephritis (GN remains unknown. Some animal studies demonstrated that parietal epithelial cells of Bowman’s capsule (PECs were the main component of proliferating cells and PEC-specific tight junction protein claudin-1 was expressed in crescentic lesions. We investigated the expression of claudin-1 in human GN. Immunohistochemistry for claudin-1 was performed on 17 kidney biopsy samples with crescent formation. Colocalization of claudin-1 with intracellular tight junction protein ZO-1 was also evaluated by immunofluorescence double staining. Claudin-1 is expressed mainly at the cell to cell contact site of proliferating cells in cellular crescentic lesions in patients with these forms of human GN. Small numbers of crescent forming cells showed extrajunctional localization of claudin-1. Colocalization of claudin-1 with ZO-1 was found at cell to cell contact sites of adjacent proliferating cells. In control samples, staining of claudin-1 was positive in PECs, but not in podocytes. Our findings suggest that claudin-1 contributes to crescent formation as a component of the tight junction protein complex that includes ZO-1. Co-localization of claudin-1 with ZO-1 implies the formation of functional tight junction complexes in crescentic lesions to prevent the interstitial damage caused by penetration of filtered molecules from Bowman’s space.

Performance evaluation of a fuel cell with NiO-YSV anode operating with natural gas; Avaliacao do desempenho de uma celula a combustivel com anodo de NiO YSZ operando com gas natural

Energy Technology Data Exchange (ETDEWEB)

Nobrega, Shayenne Diniz da; Vasconcelos, Carmel Suzarte Ayres; Lima, Luiz Rogerio Pinho de Andrade [Universidade Federal da Bahia (UFBa), Salvador, BA (Brazil). Escola Politecnica. Dept. de Ciencia e Tecnologia dos Materiais]. E-mail: shayennedn@yahoo.com.br

2008-07-01

Fuel cell is an electrochemical device that converts the chemical energy into electric energy. The natural gas, for its proven improvement in the income of the equipment in relation to other energy ones, has been very used to feed the solid oxide fuel cell (SOFC) in the generation of electric power. Ceramics of Yttria-stabilized zirconia had been used as electrolyte and when supported with nickel oxide they act as anode in the solid oxide fuel cell, due to raised ionic conductivity that these materials present in high temperatures, while lanthanum with strontium and manganite are used as cathode. In the composition of the anode, the concentration of Ni O, acting as catalytic in the YSZ confers high electric conductivity and high electrochemical activity of the reactions, providing the internal reform in the SOFC. In this work, the solid oxide fuel cell, formed by Yttria- stabilized zirconia, nickel oxide, and lanthanum with strontium and manganite were tested in the reform had been prepared samples of electrode/electrolyte for use in SOFC of the natural gas in the presence of low water text, similar condition to the operation of the SOFC, operating in temperatures range from 700 to 800 deg C. This cell also was characterized using the impedance spectroscopy technique. These results allowed the development of components of the current versus voltage. (author)

High surface area synthesis, electrochemical activity, and stability of tungsten carbide supported Pt during oxygen reduction in proton exchange membrane fuel cells

Science.gov (United States)

Chhina, H.; Campbell, S.; Kesler, O.

The oxidation of carbon catalyst supports to carbon dioxide gas leads to degradation in catalyst performance over time in proton exchange membrane fuel cells (PEMFCs). The electrochemical stability of Pt supported on tungsten carbide has been evaluated on a carbon-based gas diffusion layer (GDL) at 80 °C and compared to that of HiSpec 4000™ Pt/Vulcan XC-72R in 0.5 M H 2SO 4. Due to other electrochemical processes occurring on the GDL, detailed studies were also performed on a gold mesh substrate. The oxygen reduction reaction (ORR) activity was measured both before and after accelerated oxidation cycles between +0.6 V and +1.8 V vs. RHE. Tafel plots show that the ORR activity remained high even after accelerated oxidation tests for Pt/tungsten carbide, while the ORR activity was extremely poor after accelerated oxidation tests for HiSpec 4000™. In order to make high surface area tungsten carbide, three synthesis routes were investigated. Magnetron sputtering of tungsten on carbon was found to be the most promising route, but needs further optimization.

High surface area synthesis, electrochemical activity, and stability of tungsten carbide supported Pt during oxygen reduction in proton exchange membrane fuel cells

Energy Technology Data Exchange (ETDEWEB)

Chhina, H. [Automotive fuel cell corporation, 9000 Glenlyon Parkway, Burnaby, BC (Canada); Department of Mechanical and Industrial Engineering, 5 King' s College Road, University of Toronto, Toronto, Ontario (Canada); Campbell, S. [Automotive fuel cell corporation, 9000 Glenlyon Parkway, Burnaby, BC (Canada); Kesler, O. [Department of Mechanical and Industrial Engineering, 5 King' s College Road, University of Toronto, Toronto, Ontario (Canada)

2008-04-15

The oxidation of carbon catalyst supports to carbon dioxide gas leads to degradation in catalyst performance over time in proton exchange membrane fuel cells (PEMFCs). The electrochemical stability of Pt supported on tungsten carbide has been evaluated on a carbon-based gas diffusion layer (GDL) at 80 C and compared to that of HiSpec 4000 trademark Pt/Vulcan XC-72R in 0.5 M H{sub 2}SO{sub 4}. Due to other electrochemical processes occurring on the GDL, detailed studies were also performed on a gold mesh substrate. The oxygen reduction reaction (ORR) activity was measured both before and after accelerated oxidation cycles between +0.6 V and +1.8 V vs. RHE. Tafel plots show that the ORR activity remained high even after accelerated oxidation tests for Pt/tungsten carbide, while the ORR activity was extremely poor after accelerated oxidation tests for HiSpec 4000 trademark. In order to make high surface area tungsten carbide, three synthesis routes were investigated. Magnetron sputtering of tungsten on carbon was found to be the most promising route, but needs further optimization. (author)

Hydrogen from biomass gas steam reforming for low temperature fuel cell: energy and exergy analysis

Directory of Open Access Journals (Sweden)

A. Sordi

2009-03-01

Full Text Available This work presents a method to analyze hydrogen production by biomass gasification, as well as electric power generation in small scale fuel cells. The proposed methodology is the thermodynamic modeling of a reaction system for the conversion of methane and carbon monoxide (steam reforming, as well as the energy balance of gaseous flow purification in PSA (Pressure Swing Adsorption is used with eight types of gasification gases in this study. The electric power is generated by electrochemical hydrogen conversion in fuel cell type PEMFC (Proton Exchange Membrane Fuel Cell. Energy and exergy analyses are applied to evaluate the performance of the system model. The simulation demonstrates that hydrogen production varies with the operation temperature of the reforming reactor and with the composition of the gas mixture. The maximum H2 mole fraction (0.6-0.64 mol.mol-1 and exergetic efficiency of 91- 92.5% for the reforming reactor are achieved when gas mixtures of higher quality such as: GGAS2, GGAS4 and GGAS5 are used. The use of those gas mixtures for electric power generation results in lower irreversibility and higher exergetic efficiency of 30-30.5%.

Less-tight versus tight control of hypertension in pregnancy.

Science.gov (United States)

Magee, Laura A; von Dadelszen, Peter; Rey, Evelyne; Ross, Susan; Asztalos, Elizabeth; Murphy, Kellie E; Menzies, Jennifer; Sanchez, Johanna; Singer, Joel; Gafni, Amiram; Gruslin, Andrée; Helewa, Michael; Hutton, Eileen; Lee, Shoo K; Lee, Terry; Logan, Alexander G; Ganzevoort, Wessel; Welch, Ross; Thornton, Jim G; Moutquin, Jean-Marie

2015-01-29

The effects of less-tight versus tight control of hypertension on pregnancy complications are unclear. We performed an open, international, multicenter trial involving women at 14 weeks 0 days to 33 weeks 6 days of gestation who had nonproteinuric preexisting or gestational hypertension, office diastolic blood pressure of 90 to 105 mm Hg (or 85 to 105 mm Hg if the woman was taking antihypertensive medications), and a live fetus. Women were randomly assigned to less-tight control (target diastolic blood pressure, 100 mm Hg) or tight control (target diastolic blood pressure, 85 mm Hg). The composite primary outcome was pregnancy loss or high-level neonatal care for more than 48 hours during the first 28 postnatal days. The secondary outcome was serious maternal complications occurring up to 6 weeks post partum or until hospital discharge, whichever was later. Included in the analysis were 987 women; 74.6% had preexisting hypertension. The primary-outcome rates were similar among 493 women assigned to less-tight control and 488 women assigned to tight control (31.4% and 30.7%, respectively; adjusted odds ratio, 1.02; 95% confidence interval [CI], 0.77 to 1.35), as were the rates of serious maternal complications (3.7% and 2.0%, respectively; adjusted odds ratio, 1.74; 95% CI, 0.79 to 3.84), despite a mean diastolic blood pressure that was higher in the less-tight-control group by 4.6 mm Hg (95% CI, 3.7 to 5.4). Severe hypertension (≥160/110 mm Hg) developed in 40.6% of the women in the less-tight-control group and 27.5% of the women in the tight-control group (Phypertension. (Funded by the Canadian Institutes of Health Research; CHIPS Current Controlled Trials number, ISRCTN71416914; ClinicalTrials.gov number, NCT01192412.).

Electrochemical biosensors

CERN Document Server

Cosnier, Serge

2015-01-01

"This is an excellent book on modern electrochemical biosensors, edited by Professor Cosnier and written by leading international experts. It covers state-of-the-art topics of this important field in a clear and timely manner."-Prof. Joseph Wang, UC San Diego, USA 　"This book covers, in 13 well-illustrated chapters, the potential of electrochemical methods intimately combined with a biological component for the assay of various analytes of biological and environmental interest. Particular attention is devoted to the description of electrochemical microtools in close contact with a biological cell for exocytosis monitoring and to the use of nanomaterials in the electrochemical biosensor architecture for signal improvement. Interestingly, one chapter describes the concept and design of self-powered biosensors derived from biofuel cells. Each topic is reviewed by experts very active in the field. This timely book is well suited for providing a good overview of current research trends devoted to electrochemical...

Using sewage sludge pyrolytic gas to modify titanium alloy to obtain high-performance anodes in bio-electrochemical systems

Science.gov (United States)

Gu, Yuan; Ying, Kang; Shen, Dongsheng; Huang, Lijie; Ying, Xianbin; Huang, Haoqian; Cheng, Kun; Chen, Jiazheng; Zhou, Yuyang; Chen, Ting; Feng, Huajun

2017-12-01

Titanium is under consideration as a potential stable bio-anode because of its high conductivity, suitable mechanical properties, and electrochemical inertness in the operating potential window of bio-electrochemical systems; however, its application is limited by its poor electron-transfer capacity with electroactive bacteria and weak ability to form biofilms on its hydrophobic surface. This study reports an effective and low-cost way to convert a hydrophobic titanium alloy surface into a hydrophilic surface that can be used as a bio-electrode with higher electron-transfer rates. Pyrolytic gas of sewage sludge is used to modify the titanium alloy. The current generation, anodic biofilm formation surface, and hydrophobicity are systematically investigated by comparing bare electrodes with three modified electrodes. Maximum current density (15.80 A/m2), achieved using a modified electrode, is 316-fold higher than that of the bare titanium alloy electrode (0.05 A/m2) and that achieved by titanium alloy electrodes modified by other methods (12.70 A/m2). The pyrolytic gas-modified titanium alloy electrode can be used as a high-performance and scalable bio-anode for bio-electrochemical systems because of its high electron-transfer rates, hydrophilic nature, and ability to achieve high current density.

Current Constriction at Electrode/Electrolyte Interfaces in Solid Oxide Cell Electrochemical Devices Calculated Via 3D Reconstructions

DEFF Research Database (Denmark)

Nielsen, Jimmi; Jørgensen, Peter Stanley; Graves, Christopher R.

2016-01-01

Electrochemical devices such as batteries, fuel cells, electrolysers, electrochemical reactors and electrochemical sensors are important technologies for the present and the future society. For further improvement or maturing of the various technologies it is important to understand, characterize...

Nanostructured surfaces for analysis of anticancer drug and cell diagnosis based on electrochemical and SERS tools

Science.gov (United States)

El-Said, Waleed A.; Yoon, Jinho; Choi, Jeong-Woo

2018-04-01

Discovering new anticancer drugs and screening their efficacy requires a huge amount of resources and time-consuming processes. The development of fast, sensitive, and nondestructive methods for the in vitro and in vivo detection of anticancer drugs' effects and action mechanisms have been done to reduce the time and resources required to discover new anticancer drugs. For the in vitro and in vivo detection of the efficiency, distribution, and action mechanism of anticancer drugs, the applications of electrochemical techniques such as electrochemical cell chips and optical techniques such as surface-enhanced Raman spectroscopy (SERS) have been developed based on the nanostructured surface. Research focused on electrochemical cell chips and the SERS technique have been reviewed here; electrochemical cell chips based on nanostructured surfaces have been developed for the in vitro detection of cell viability and the evaluation of the effects of anticancer drugs, which showed the high capability to evaluate the cytotoxic effects of several chemicals at low concentrations. SERS technique based on the nanostructured surface have been used as label-free, simple, and nondestructive techniques for the in vitro and in vivo monitoring of the distribution, mechanism, and metabolism of different anticancer drugs at the cellular level. The use of electrochemical cell chips and the SERS technique based on the nanostructured surface should be good tools to detect the effects and action mechanisms of anticancer drugs.

Prime tight frames

DEFF Research Database (Denmark)

Lemvig, Jakob; Miller, Christopher; Okoudjou, Kasso A.

2014-01-01

to suggest effective analysis and synthesis computation strategies for such frames. Finally, we describe all prime frames constructed from the spectral tetris method, and, as a byproduct, we obtain a characterization of when the spectral tetris construction works for redundancies below two.......We introduce a class of finite tight frames called prime tight frames and prove some of their elementary properties. In particular, we show that any finite tight frame can be written as a union of prime tight frames. We then characterize all prime harmonic tight frames and use thischaracterization...

Analysis of Critical Permeabilty, Capillary Pressure and Electrical Properties for Mesaverde Tight Gas Sandstones from Western U.S. Basins

Energy Technology Data Exchange (ETDEWEB)

Alan Byrnes; Robert Cluff; John Webb; John Victorine; Ken Stalder; Daniel Osburn; Andrew Knoderer; Owen Metheny; Troy Hommertzheim; Joshua Byrnes; Daniel Krygowski; Stefani Whittaker

2008-06-30

Although prediction of future natural gas supply is complicated by uncertainty in such variables as demand, liquefied natural gas supply price and availability, coalbed methane and gas shale development rate, and pipeline availability, all U.S. Energy Information Administration gas supply estimates to date have predicted that Unconventional gas sources will be the dominant source of U.S. natural gas supply for at least the next two decades (Fig. 1.1; the period of estimation). Among the Unconventional gas supply sources, Tight Gas Sandstones (TGS) will represent 50-70% of the Unconventional gas supply in this time period (Fig. 1.2). Rocky Mountain TGS are estimated to be approximately 70% of the total TGS resource base (USEIA, 2005) and the Mesaverde Group (Mesaverde) sandstones represent the principal gas productive sandstone unit in the largest Western U.S. TGS basins including the basins that are the focus of this study (Washakie, Uinta, Piceance, northern Greater Green River, Wind River, Powder River). Industry assessment of the regional gas resource, projection of future gas supply, and exploration programs require an understanding of reservoir properties and accurate tools for formation evaluation. The goal of this study is to provide petrophysical formation evaluation tools related to relative permeability, capillary pressure, electrical properties and algorithms for wireline log analysis. Detailed and accurate moveable gas-in-place resource assessment is most critical in marginal gas plays and there is need for quantitative tools for definition of limits on gas producibility due to technology and rock physics and for defining water saturation. The results of this study address fundamental questions concerning: (1) gas storage; (2) gas flow; (3) capillary pressure; (4) electrical properties; (5) facies and upscaling issues; (6) wireline log interpretation algorithms; and (7) providing a web-accessible database of advanced rock properties. The following text

Electrochemically Modulated Gas/Liquid Separation Technology for In Situ Resource Utilization Process Streams, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — In this phase I program MicroCell Technologies, LLC (MCT) proposes to demonstrate the feasibility of an electrochemically modulated phase separator for in situ...

Structural diagenesis in Upper Carboniferous tight gas sandstones. Lessons learned from the Piesberg analog study

Energy Technology Data Exchange (ETDEWEB)

Steindorf, P.; Hoehne, M.; Becker, S.; Hilgers, C. [RWTH Aachen Univ. (Germany). Energy and Mineral Resources Group (EMR); Koehrer, B. [Wintershall Holding GmbH, Barnstorf (Germany)

2013-08-01

Upper Carboniferous tight gas sandstone reservoirs in NW-Germany consist of thick successions of cyclothems. Our focus is the Westphalian D of the Piesberg quarry near Osnabrueck, which exposes cemented, faulted and jointed third-order coarse- to fine-grained sandstone cycles separated by anthracite coal seams. We characterize the rocks and the lateral variation of rock properties such as porosity to better constrain input data for reservoir modelling. Three cycles are exposed, each approximately 50 m thick. Rock types can be clearly distinguished by spectral gamma ray in the quarry. Sandstones are intensely compacted and cemented with quartz and generally characterized by low porosities < 8 % (Hepycnometry on plugs and cuttings). Porosities are secondary and mainly related to detrital carbonate dissolution. Around faults dissolution is higher and the porosities can increase to up to 25%. The normal faults show different throws in the quarry and bands of shale and coal have smeared into the fault at juxtaposed beds, which may result in compartments. They dominantly strike W-E and NNW-SSE, but subordinate NE-SW striking fault patterns are also present. Joints were analyzed in a 50 x 50 m section of the quarry wall using Lidar (Light detection and ranging) laser scanning, which allows the characterization of the lithology and quantitative measurement of bedding and fracture orientation data in inaccessible areas. NNE-SSW and W-E joint sets are accompanied by northeasterly and northwesterly striking sets. Around faults, fault planes and fractures are cemented with quartz veins, showing localized mass transport. Due to the intense cementation, the sandstones can reach uniaxial strengths of more than 100 MPa normal to bedding, and approximately 50 MPa parallel to bedding. Sandstone beds within and close to faults are leached by fluids, and their uniaxial strength is reduced by a factor of more than two. Our high resolution field data enables a better understanding of

Electrochemical Behaviour of a PPy(DBS)/Polyacrylonitrile (PAN):LITF:EC:PC/ Li Cell

DEFF Research Database (Denmark)

Vidanapathirana, K.; Careem, M.A.; Skaarup, Steen

2006-01-01

The electrochemical behaviour of Li rechargeable cells with Polypyrrole (PPy) as the cathode material was investigated using cyclic voltammetry. The PPy used was doped with the large surfactant anion dodecyl benzenesulphonate (DBS-). The cells were constructed with PAN:LiTF:EC:PC gel electrolyte...... with Li as anode. The results indicate that during the first reduction, cations are inserted into the PPy film forming LiDBS neutral salt. During the next oxidation/reduction cycles, the mechanism then switches to anion movement. Cyclic voltammetry studies also verified that complete electrochemical...

Electrochemical Characterization of Ni/ScYSZ Electrodes as SOFC Anodes

DEFF Research Database (Denmark)

Ramos, Tania; Søgaard, Martin; Mogensen, Mogens Bjerg

2014-01-01

Investigations of Ni/ScYSZ cermets were performed by electrochemical impedance spectroscopy (EIS) using different symmetric designs: electrolyte supported (ESC) and anode supported (ASC) cells. The obtained spectra were analyzed using distribution of relaxation times (DRT), and complex non......-linear least squares fitting (CNLS). Depending on the cell design, one or two low frequency gas transport related processes have been identified, and fitted with generalized finite Warburg (GFW) elements. One was related to gas diffusion in a stagnant layer above the anode (ESC+ASC), and the other to gas...... diffusion in the anode support layer (ASC). A higher frequency process has also been identified, and correlated to the charge transfer (CT) combined with ionic conduction in the ceramic matrix. This has been fitted using a transmission line model (TML), which correlates the exhibited responses...

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

Directory of Open Access Journals (Sweden)

Maximilian Fleischer

2013-04-01

Full Text Available Half-cell potentials of the electrochemical cell Au, VWT | YSZ | Au are analyzed in dependence on oxygen and ammonia concentration at 550 °C. One of the gold electrodes is covered with a porous SCR catalyst, vanadia-tungstenia-titania (VWT. The cell is utilized as a potentiometric ammonia gas sensor and provides a semi-logarithmic characteristic curve with a high NH3 sensitivity and selectivity. The analyses of the Au | YSZ and Au, VWT | YSZ half-cells are conducted to describe the non-equilibrium behavior of the sensor device in light of mixed potential theory. Both electrode potentials provide a dependency on the NH3 concentration, whereby VWT, Au | YSZ shows a stronger effect which increases with increasing VWT coverage. The potential shifts in the anodic direction confirm the formation of mixed potentials at both electrodes resulting from electrochemical reactions of O2 and NH3 at the three-phase boundary. Polarization curves indicate Butler-Volmer-type kinetics. Modified polarization curves of the VWT covered electrode show an enhanced anodic reaction and an almost unaltered cathodic reaction. The NH3 dependency is dominated by the VWT coverage and it turns out that the catalytic properties of the VWT thick film are responsible for the electrode potential shift

Model Based Analysis of Forced and Natural Convection Effects in an Electrochemical Cell

Directory of Open Access Journals (Sweden)

D Brunner

2017-03-01

Full Text Available High purity copper, suitable for electrical applications, can only be obtained by electro-winning. The hallmark of this process is its self-induced natural convection through density variations of the electrolyte at both anode and cathode. In order to do this, first the full dynamic complexity of the process needs to be understood. Thus an OpenFoam®-based 2D model of the process has been created. This finite-volume multiphysics approach solves the laminar momentum and copper-ion species conservation equations, as well as local copper-ion conversion kinetics. It uses a Boussinesq approximation to simulate the species-momentum coupling, namely natural draft forces induced by variations of the spatial copper concentration within the fluid. The model shows good agreement with benchmark-cases of real-life electrochemical cells found in literature. An additional flow was imposed at the bottom of a small scale electrochemical cell in order to increase the ionic transport and thereby increase the overall performance of the cell. In a small scale electrochemical cell in strictly laminar flow, the overall performance could be increased and stratification decreased.

Caveolin1 Is Required for Th1 Cell Infiltration, but Not Tight Junction Remodeling, at the Blood-Brain Barrier in Autoimmune Neuroinflammation

Directory of Open Access Journals (Sweden)

Sarah E. Lutz

2017-11-01

Full Text Available Lymphocytes cross vascular boundaries via either disrupted tight junctions (TJs or caveolae to induce tissue inflammation. In the CNS, Th17 lymphocytes cross the blood-brain barrier (BBB before Th1 cells; yet this differential crossing is poorly understood. We have used intravital two-photon imaging of the spinal cord in wild-type and caveolae-deficient mice with fluorescently labeled endothelial tight junctions to determine how tight junction remodeling and caveolae regulate CNS entry of lymphocytes during the experimental autoimmune encephalomyelitis (EAE model for multiple sclerosis. We find that dynamic tight junction remodeling occurs early in EAE but does not depend upon caveolar transport. Moreover, Th1, but not Th17, lymphocytes are significantly reduced in the inflamed CNS of mice lacking caveolae. Therefore, tight junction remodeling facilitates Th17 migration across the BBB, whereas caveolae promote Th1 entry into the CNS. Moreover, therapies that target both tight junction degradation and caveolar transcytosis may limit lymphocyte infiltration during inflammation.

Nano-electrochemical deposition of fuel cells electrocatalysts

CSIR Research Space (South Africa)

Mathe

2008-11-01

Full Text Available stream_source_info Mathe_2008.pdf.txt stream_content_type text/plain stream_size 34594 Content-Encoding UTF-8 stream_name Mathe_2008.pdf.txt Content-Type text/plain; charset=UTF-8 1 Nano-electrochemical deposition... of fuel cells electrocatalysts MK MATHE a,*, TS MKWIZU a,b, I CUKROWSKI b * ,aCSIR Materials Science and Manufacturing, Energy and Processes, PO Box 395, Pretoria, 0001 bDepartment of Chemistry, University of Pretoria, Pretoria, 0002 Email: kmathe...

Performance Evaluation of Electrochem's PEM Fuel Cell Power Plant for NASA's 2nd Generation Reusable Launch Vehicle

Science.gov (United States)

Kimble, Michael C.; Hoberecht, Mark

2003-01-01

NASA's Next Generation Launch Technology (NGLT) program is being developed to meet national needs for civil and commercial space access with goals of reducing the launch costs, increasing the reliability, and reducing the maintenance and operating costs. To this end, NASA is considering an all- electric capability for NGLT vehicles requiring advanced electrical power generation technology at a nominal 20 kW level with peak power capabilities six times the nominal power. The proton exchange membrane (PEM) fuel cell has been identified as a viable candidate to supply this electrical power; however, several technology aspects need to be assessed. Electrochem, Inc., under contract to NASA, has developed a breadboard power generator to address these technical issues with the goal of maximizing the system reliability while minimizing the cost and system complexity. This breadboard generator operates with dry hydrogen and oxygen gas using eductors to recirculate the gases eliminating gas humidification and blowers from the system. Except for a coolant pump, the system design incorporates passive components allowing the fuel cell to readily follow a duty cycle profile and that may operate at high 6:1 peak power levels for 30 second durations. Performance data of the fuel cell stack along with system performance is presented to highlight the benefits of the fuel cell stack design and system design for NGLT vehicles.

Electrochemical Quantification of Extracellular Local H2O2 Kinetics Originating from Single Cells.

Science.gov (United States)

Bozem, Monika; Knapp, Phillip; Mirčeski, Valentin; Slowik, Ewa J; Bogeski, Ivan; Kappl, Reinhard; Heinemann, Christian; Hoth, Markus

2017-05-15

H 2 O 2 is produced by all eukaryotic cells under physiological and pathological conditions. Due to its enormous relevance for cell signaling at low concentrations and antipathogenic function at high concentrations, precise quantification of extracellular local H 2 O 2 concentrations ([H 2 O 2 ]) originating from single cells is required. Using a scanning electrochemical microscope and bare platinum disk ultramicroelectrodes, we established sensitive long-term measurements of extracellular [H 2 O 2 ] kinetics originating from single primary human monocytes (MCs) ex vivo. For the electrochemical techniques square wave voltammetry, cyclic and linear scan voltammetry, and chronoamperometry, detection limits for [H 2 O 2 ] were determined to be 5, 50, and 500 nM, respectively. Following phorbol ester stimulation, local [H 2 O 2 ] 5-8 μm above a single MC increased by 3.4 nM/s within the first 10 min before reaching a plateau. After extracellular addition of H 2 O 2 to an unstimulated MC, the local [H 2 O 2 ] decreased on average by 4.2 nM/s due to degradation processes of the cell. Using the scanning mode of the setup, we found that H 2 O 2 is evenly distributed around the producing cell and can still be detected up to 30 μm away from the cell. The electrochemical single-cell measurements were validated in MC populations using electron spin resonance spectroscopy and the Amplex ® UltraRed assay. Innovation and Conclusion: We demonstrate a highly sensitive, spatially, and temporally resolved electrochemical approach to monitor dynamics of production and degradation processes for H 2 O 2 separately. Local extracellular [H 2 O 2 ] kinetics originating from single cells is quantified in real time. Antioxid. Redox Signal. 00, 000-000.

Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

DEFF Research Database (Denmark)

Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Kær, Søren Knudsen

2008-01-01

This work presents the development of an equivalent circuit model of a 65 cell high temperature PEM (HTPEM) fuel cell stack using Electrochemical Impedance Spectroscopy (EIS). The HTPEM fuel cell membranes used are PBI-based and uses phosphoric acid as proton conductor. The operating temperature...

A Study of the Influence of Gas Channel Parameters on HT-PEM Fuel Cell Performance Using FEM Analysis

Directory of Open Access Journals (Sweden)

Ionescu Viorel

2016-01-01

Full Text Available Proton Exchange Membrane Fuel Cells (PEMFC are highly efficient power generators, achieving up to 50–60% conversion efficiency, even in sizes of a few kilowatts. Comsol Multiphysics, a commercial solver based on the Finite Element Method (FEM was used for developing a three dimensional model of a high temperature PEMFC that can deal with both anode and cathode flow field for examining the micro flow channel with electrochemical reaction. Cathode gas flow velocity influence on the cell performance was investigated at first. Polarization curves for three different channel widths (0.8, 1.6 and 2.4 mm and three different channel depths (1, 2 and 3 mm were computed at a cathode inlet flow velocity of 0.06 m/s. Oxygen molar concentration at cathode catalyst layer-GDL channel interface and local current density variation along the cell length were also studied for specific gas channel geometries.

Design of an electrochemical cell for in situ XAS studies

Energy Technology Data Exchange (ETDEWEB)

Watanabe, N. [Instituto de Quimica, Universidade Estadual de Campinas (UNICAMP), Box 6154, CEP 13083-970, Campinas, SP (Brazil); Morais, J. [Instituto de Fisica, Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Goncalves, 9500, Bairro Agronomia, CP 15051, CEP 91501-970, Porto Alegre, RS (Brazil); Alves, M.C.M. [Instituto de Quimica, Universidade Federal do Rio Grande do Sul (UFRGS), Avenida Bento Goncalves, 9500, Bairro Agronomia, CP 15003, CEP 91501-970, Porto Alegre, RS (Brazil)], E-mail: maria@iq.ufrgs.br

2007-05-15

In situ X-ray absorption spectroscopy (XAS) studies have been carried out on the electrochemical insertion of Co metal particles in polypyrrole. This has become possible due to the development of an electrochemical cell to allow XAS studies in fluorescence geometry under steady-state conditions. The experimental set-up allows the in situ monitoring of the structural and electronic changes of the selected atom in a matrix. The project of the electrochemical cell is presented with the results obtained at different stages of the electrochemical process. XANES and EXAFS results showed that the initial stage of the cobalt insertion in polypyrrole took place in an ionic form, like [-[(C{sub 4}H{sub 2}N){sub 3}CH{sub 3}(CH{sub 2}){sub 11}OSO{sub 3}{sup -}]{sub 6}Co{sup 2+}] with posterior reduction to a metallic form. The quantitative analysis of the first shell shows that, at -0.60 V, the cobalt atoms are surrounded by 6 ({+-}0.5) atoms located at 2.12 ({+-}0.05) A with a large Debye-Waller factor ({sigma}{sup 2}) value of 0.0368 ({+-}0.0074). At -0.80 V, two distances of R = 1.99 ({+-}0.01) and R = 2.50 ({+-}0.01) A show the coexistence of cobalt in the oxidized and reduced (Co{sup 0}) forms. The Co-Co distance corresponds to that of bulk cobalt. At -1.20 V, the obtained values of N = 12 ({+-}0.5) and R = 2.56 ({+-}0.01) A and a Debye-Waller factor of 0.0176 ({+-}0.0004) suggest the formation of metallic cobalt in a quite disordered form.

Electrochemical approach for monitoring the effect of anti tubulin drugs on breast cancer cells based on silicon nanograss electrodes

International Nuclear Information System (INIS)

Zanganeh, Somayeh; Khosravi, Safoora; Namdar, Naser; Amiri, Morteza Hassanpour; Gharooni, Milad; Abdolahad, Mohammad

2016-01-01

One of the most interested molecular research in the field of cancer detection is the mechanism of drug effect on cancer cells. Translating molecular evidence into electrochemical profiles would open new opportunities in cancer research. In this manner, applying nanostructures with anomalous physical and chemical properties as well as biocompatibility would be a suitable choice for the cell based electrochemical sensing. Silicon based nanostructure are the most interested nanomaterials used in electrochemical biosensors because of their compatibility with electronic fabrication process and well engineering in size and electrical properties. Here we apply silicon nanograss (SiNG) probing electrodes produced by reactive ion etching (RIE) on silicon wafer to electrochemically diagnose the effect of anticancer drugs on breast tumor cells. Paclitaxel (PTX) and mebendazole (MBZ) drugs have been used as polymerizing and depolymerizing agents of microtubules. PTX would perturb the anodic/cathodic responses of the cell-covered biosensor by binding phosphate groups to deformed proteins due to extracellular signal-regulated kinase (ERK"1"/"2) pathway. MBZ induces accumulation of Cytochrome C in cytoplasm. Reduction of the mentioned agents in cytosol would change the ionic state of the cells monitored by silicon nanograss working electrodes (SiNGWEs). By extending the contacts with cancer cells, SiNGWEs can detect minor signal transduction and bio recognition events, resulting in precise biosensing. Effects of MBZ and PTX drugs, (with the concentrations of 2 nM and 0.1 nM, respectively) on electrochemical activity of MCF-7 cells are successfully recorded which are corroborated by confocal and flow cytometry assays. - Highlights: • Electrochemical effect of MBZ and PTX (anti tubulin drugs) on breast cancer cells was detected. • Detection was carried by silicon nanograss electrodes(SiNGEs). • Signaling pathways activated in the cells by drug treatment, change the anodic

Electrochemical approach for monitoring the effect of anti tubulin drugs on breast cancer cells based on silicon nanograss electrodes

Energy Technology Data Exchange (ETDEWEB)

Zanganeh, Somayeh; Khosravi, Safoora; Namdar, Naser; Amiri, Morteza Hassanpour; Gharooni, Milad [Nano Electronic Center of Excellence, Nano Bio Electronic Devices Lab, School of Electrical and Computer Eng, University of Tehran, P.O. Box 14395/515, Tehran (Iran, Islamic Republic of); Nano Electronic Center of Excellence, Thin Film and Nanoelectronic Lab, School of Electrical and Computer Eng, University of Tehran, P.O. Box 14395/515, Tehran (Iran, Islamic Republic of); Abdolahad, Mohammad, E-mail: m.abdolahad@ut.ac.ir [Nano Electronic Center of Excellence, Nano Bio Electronic Devices Lab, School of Electrical and Computer Eng, University of Tehran, P.O. Box 14395/515, Tehran (Iran, Islamic Republic of); Nano Electronic Center of Excellence, Thin Film and Nanoelectronic Lab, School of Electrical and Computer Eng, University of Tehran, P.O. Box 14395/515, Tehran (Iran, Islamic Republic of)

2016-09-28

One of the most interested molecular research in the field of cancer detection is the mechanism of drug effect on cancer cells. Translating molecular evidence into electrochemical profiles would open new opportunities in cancer research. In this manner, applying nanostructures with anomalous physical and chemical properties as well as biocompatibility would be a suitable choice for the cell based electrochemical sensing. Silicon based nanostructure are the most interested nanomaterials used in electrochemical biosensors because of their compatibility with electronic fabrication process and well engineering in size and electrical properties. Here we apply silicon nanograss (SiNG) probing electrodes produced by reactive ion etching (RIE) on silicon wafer to electrochemically diagnose the effect of anticancer drugs on breast tumor cells. Paclitaxel (PTX) and mebendazole (MBZ) drugs have been used as polymerizing and depolymerizing agents of microtubules. PTX would perturb the anodic/cathodic responses of the cell-covered biosensor by binding phosphate groups to deformed proteins due to extracellular signal-regulated kinase (ERK{sup 1/2}) pathway. MBZ induces accumulation of Cytochrome C in cytoplasm. Reduction of the mentioned agents in cytosol would change the ionic state of the cells monitored by silicon nanograss working electrodes (SiNGWEs). By extending the contacts with cancer cells, SiNGWEs can detect minor signal transduction and bio recognition events, resulting in precise biosensing. Effects of MBZ and PTX drugs, (with the concentrations of 2 nM and 0.1 nM, respectively) on electrochemical activity of MCF-7 cells are successfully recorded which are corroborated by confocal and flow cytometry assays. - Highlights: • Electrochemical effect of MBZ and PTX (anti tubulin drugs) on breast cancer cells was detected. • Detection was carried by silicon nanograss electrodes(SiNGEs). • Signaling pathways activated in the cells by drug treatment, change the

In-situ study of the gas-phase composition and temperature of an intermediate-temperature solid oxide fuel cell anode surface fed by reformate natural gas

Science.gov (United States)

Santoni, F.; Silva Mosqueda, D. M.; Pumiglia, D.; Viceconti, E.; Conti, B.; Boigues Muñoz, C.; Bosio, B.; Ulgiati, S.; McPhail, S. J.

2017-12-01

An innovative experimental setup is used for in-depth and in-operando characterization of solid oxide fuel cell anodic processes. This work focuses on the heterogeneous reactions taking place on a 121 cm2 anode-supported cell (ASC) running with a H2, CH4, CO2, CO and steam gas mixture as a fuel, using an operating temperature of 923 K. The results have been obtained by analyzing the gas composition and temperature profiles along the anode surface in different conditions: open circuit voltage (OCV) and under two different current densities, 165 mA cm-2 and 330 mA cm-2, corresponding to 27% and 54% of fuel utilization, respectively. The gas composition and temperature analysis results are consistent, allowing to monitor the evolution of the principal chemical and electrochemical reactions along the anode surface. A possible competition between CO2 and H2O in methane internal reforming is shown under OCV condition and low current density values, leading to two different types of methane reforming: Steam Reforming and Dry Reforming. Under a current load of 40 A, the dominance of exothermic reactions leads to a more marked increase of temperature in the portion of the cell close to the inlet revealing that current density is not uniform along the anode surface.

Carbon Nanotube Thread Electrochemical Cell: Detection of Heavy Metals.

Science.gov (United States)

Zhao, Daoli; Siebold, David; Alvarez, Noe T; Shanov, Vesselin N; Heineman, William R

2017-09-19

In this work, all three electrodes in an electrochemical cell were fabricated based on carbon nanotube (CNT) thread. CNT thread partially insulated with a thin polystyrene coating to define the microelectrode area was used as the working electrode; bare CNT thread was used as the auxiliary electrode; and a micro quasi-reference electrode was fabricated by electroplating CNT thread with Ag and then anodizing it in chloride solution to form a layer of AgCl. The Ag|AgCl coated CNT thread electrode provided a stable potential comparable to the conventional liquid-junction type Ag|AgCl reference electrode. The CNT thread auxiliary electrode provided a stable current, which is comparable to a Pt wire auxiliary electrode. This all-CNT thread three electrode cell has been evaluated as a microsensor for the simultaneous determination of trace levels of heavy metal ions by anodic stripping voltammetry (ASV). Hg 2+ , Cu 2+ , and Pb 2+ were used as a representative system for this study. The calculated detection limits (based on the 3σ method) with a 120 s deposition time are 1.05, 0.53, and 0.57 nM for Hg 2+ , Cu 2+ , and Pb 2+ , respectively. These electrodes significantly reduce the dimensions of the conventional three electrode electrochemical cell to the microscale.

Injection molded polymer chip for electrochemical and electrophysiological recordings from single cells

DEFF Research Database (Denmark)

Tanzi, Simone; Larsen, Simon Tylsgaard; Taboryski, Rafael J.

We present a novel method to fabricate an all in polymer injection molded chip for electrochemical cell recordings and lateral cell trapping. The complete device is molded in thermoplastic polymer and it results from assembling two halves. We tested spin-coated conductive polymer poly(3,4-ethylen...

Modeling electrochemical performance in large scale proton exchange membrane fuel cell stacks

Energy Technology Data Exchange (ETDEWEB)

Lee, J H [Los Alamos National Lab., NM (United States); Lalk, T R [Texas A and M Univ., College Station, TX (United States). Dept. of Mechanical Engineering; Appleby, A J [Center for Electrochemical Studies and Hydrogen Research, Texas Engineering Experimentation Station, Texas A and M Univ., College Station, TX (United States)

1998-02-01

The processes, losses, and electrical characteristics of a Membrane-Electrode Assembly (MEA) of a Proton Exchange Membrane Fuel Cell (PEMFC) are described. In addition, a technique for numerically modeling the electrochemical performance of a MEA, developed specifically to be implemented as part of a numerical model of a complete fuel cell stack, is presented. The technique of calculating electrochemical performance was demonstrated by modeling the MEA of a 350 cm{sup 2}, 125 cell PEMFC and combining it with a dynamic fuel cell stack model developed by the authors. Results from the demonstration that pertain to the MEA sub-model are given and described. These include plots of the temperature, pressure, humidity, and oxygen partial pressure distributions for the middle MEA of the modeled stack as well as the corresponding current produced by that MEA. The demonstration showed that models developed using this technique produce results that are reasonable when compared to established performance expectations and experimental results. (orig.)

Novel single-cell mega-size chambers for electrochemical etching of panorama position-sensitive polycarbonate ion image detectors

Science.gov (United States)

Sohrabi, Mehdi

2017-11-01

A novel development is made here by inventing panorama single-cell mega-size electrochemical etching (MS-ECE) chamber systems for processing panorama position-sensitive mega-size polycarbonate ion image detectors (MS-PCIDs) of potential for many neutron and ion detection applications in particular hydrogen ions or proton tracks and images detected for the first time in polycarbonates in this study. The MS-PCID is simply a large polycarbonate sheet of a desired size. The single-cell MS-ECE invented consists of two large equally sized transparent Plexiglas sheets as chamber walls holding a MS-PCID and the ECE chamber components tightly together. One wall has a large flat stainless steel electrode (dry cell) attached to it which is directly in contact with the MS-PCID and the other wall has a rod electrode with two holes to facilitate feeding and draining out the etching solution from the wet cell. A silicon rubber washer plays the role of the wet cell to hold the etchant and the electrical insulator to isolate the dry cell from the wet cell. A simple 50 Hz-HV home-made generator provides an adequate field strength through the two electrodes across the MS-ECE chamber. Two panorama single-cell MS-ECE chamber systems (circular and rectangular shapes) constructed were efficiently applied to processing the MS-PCIDs for 4π ion emission image detection of different gases in particular hydrogen ions or protons in a 3.5 kJ plasma focus device (PFD as uniquely observed by the unaided eyes). The panorama MS-PCID/MS-ECE image detection systems invented are novel with high potential for many applications in particular as applied to 4π panorama ion emission angular distribution image detection studies in PFD space, some results of which are presented and discussed.

Gas-phase decontamination demonstration on PORTS cell X-25-4-2. Final technology status report

International Nuclear Information System (INIS)

Riddle, R.J.

1997-09-01

The Long-Term, Low Temperature (LTLT) process is a gas-phase in situ decontamination technique which has been tested by LMES/K-25 personnel on the laboratory scale with promising results. The purpose of the Gas-Phase Decontamination Demonstration at PORTS was to evaluate the LTLT process on an actual diffusion cascade cell at conditions similar to those used in the laboratory testing. The demonstration was conducted on PORTS diffusion cell X-25-4-2 which was one of the X-326 Building cells which was permanently shutdown as part of the Suspension of HEU Production at PORTS. The demonstration full-scale test consisted of rendering the cell leak-tight through the installation of Dresser seals onto the process seals, exposing the cell to the oxidants ClF 3 and F 2 for a period of 105 days and evaluating the effect of the clean-up treatment on cell samples and coupons representing the major diffusion cascade materials of construction. The results were extrapolated to determine the effectiveness of LTLT decontamination over the range of historical uranium isotope assays present in the diffusion complex. It was determined that acceptable surface contamination levels could be obtained in all of the equipment in the lower assay cascades which represents the bulk of the equipment contained in the diffusion complex

Ethanol internal steam reforming in intermediate temperature solid oxide fuel cell

Science.gov (United States)

Diethelm, Stefan; Van herle, Jan

This study investigates the performance of a standard Ni-YSZ anode supported cell under ethanol steam reforming operating conditions. Therefore, the fuel cell was directly operated with a steam/ethanol mixture (3 to 1 molar). Other gas mixtures were also used for comparison to check the conversion of ethanol and of reformate gases (H 2, CO) in the fuel cell. The electrochemical properties of the fuel cell fed with four different fuel compositions were characterized between 710 and 860 °C by I- V and EIS measurements at OCV and under polarization. In order to elucidate the limiting processes, impedance spectra obtained with different gas compositions were compared using the derivative of the real part of the impedance with respect of the natural logarithm of the frequency. Results show that internal steam reforming of ethanol takes place significantly on Ni-YSZ anode only above 760 °C. Comparisons of results obtained with reformate gas showed that the electrochemical cell performance is dominated by the conversion of hydrogen. The conversion of CO also occurs either directly or indirectly through the water-gas shift reaction but has a significant impact on the electrochemical performance only above 760 °C.

Diffuse-charge effects on the transient response of electrochemical cells

NARCIS (Netherlands)

Soestbergen, M.; Biesheuvel, P.M.; Bazant, M.Z.

2010-01-01

We present theoretical models for the time-dependent voltage of an electrochemical cell in response to a current step, including effects of diffuse charge (or “space charge”) near the electrodes on Faradaic reaction kinetics. The full model is based on the classical Poisson-Nernst-Planck equations

Electrochemical and partial oxidation of methane

Science.gov (United States)

Singh, Rahul

2008-10-01

Hydrogen has been the most common fuel used for the fuel cell research but there remains challenging technological hurdles and storage issues with hydrogen fuel. The direct electrochemical oxidation of CH4 (a major component of natural gas) in a solid oxide fuel cell (SOFC) to generate electricity has a potential of commercialization in the area of auxiliary and portable power units and battery chargers. They offer significant advantages over an external reformer based SOFC, namely, (i) simplicity in the overall system architecture and balance of plant, (ii) more efficient and (iii) availability of constant concentration of fuel in the anode compartment of SOFC providing stability factor. The extreme operational temperature of a SOFC at 700-1000°C provides a thermodynamically favorable pathway to deposit carbon on the most commonly used Ni anode from CH4 according to the following reaction (CH4 = C + 2H2), thus deteriorating the cell performance, stability and durability. The coking problem on the anode has been a serious and challenging issue faced by the catalyst research community worldwide. This dissertation presents (i) a novel fabricated bi-metallic Cu-Ni anode by electroless plating of Cu on Ni anode demonstrating significantly reduced or negligible coke deposition on the anode for CH4 and natural gas fuel after long term exposure, (ii) a thorough microstructural examination of Ni and Cu-Ni anode exposed to H2, CH4 and natural gas after long term exposure at 750°C by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction and (iii) in situ electrochemical analysis of Ni and Cu-Ni for H2, CH4 and natural gas during long term exposure at 750°C by impedance spectroscopy. A careful investigation of variation in the microstructure and performance characteristics (voltage-current curve and impedance) of Ni and Cu-Ni anode before and after a long term exposure of CH4 and natural gas would allow us to test the validation of a

Thermal regeneration of an electrochemical concentration cell

Science.gov (United States)

Krumpelt, Michael; Bates, John K.

1981-01-01

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.

The use of electrochemical impedance spectroscopy (EIS) in the evaluation of the electrochemical properties of a microbial fuel cell.

Science.gov (United States)

Manohar, Aswin K; Bretschger, Orianna; Nealson, Kenneth H; Mansfeld, Florian

2008-04-01

Electrochemical impedance spectroscopy (EIS) has been used to determine several electrochemical properties of the anode and cathode of a mediator-less microbial fuel cell (MFC) under different operational conditions. These operational conditions included a system with and without the bacterial catalyst and EIS measurements at the open-circuit potential of the anode and the cathode or at an applied cell voltage. In all cases the impedance spectra followed a simple one-time-constant model (OTCM) in which the solution resistance is in series with a parallel combination of the polarization resistance and the electrode capacitance. Analysis of the impedance spectra showed that addition of Shewanella oneidensis MR-1 to a solution of buffer and lactate greatly increased the rate of the lactate oxidation at the anode under open-circuit conditions. The large decrease of open-circuit potential of the anode increased the cell voltage of the MFC and its power output. Measurements of impedance spectra for the MFC at different cell voltages resulted in determining the internal resistance (R(int)) of the MFC and it was found that R(int) is a function of cell voltage. Additionally, R(int) was equal to R(ext) at the cell voltage corresponding to maximum power, where R(ext) is the external resistance that must be applied across the circuit to obtain the maximum power output.

Electrochemical promotion of NO reduction by hydrogen on a platinum/polybenzimidazole catalyst

DEFF Research Database (Denmark)

Petrushina, Irina; Bandur, Viktor; Cappeln, Frederik Vilhelm

2003-01-01

The electrochemical promotion of catalytic NO reduction by hydrogen was studied using a (NO, H-2, Ar), Pt polybenzimidazole (PBI)-H3PO4\\Pt, (H-2, Ar) fuel cell at 135degreesC. A mixture of NO/H-2/Ar was used as the working mixture at one electrode and a mixture of H-2/Ar was used as reference and...... at the negative polarization can be attributed to the electrochemical production of the promoters. At low gas flow rates, a charge-induced change of the strength of chemisorptive bonds can take place.......The electrochemical promotion of catalytic NO reduction by hydrogen was studied using a (NO, H-2, Ar), Pt polybenzimidazole (PBI)-H3PO4\\Pt, (H-2, Ar) fuel cell at 135degreesC. A mixture of NO/H-2/Ar was used as the working mixture at one electrode and a mixture of H-2/Ar was used as reference...... and counter gas at the other electrode. Products of NO reduction (N-2 and H2O) were analyzed by an on-line mass spectrometer. At high NO+H-2+Ar flow rate (17 mL/min; 17 and 354 mL/min, respectively, at atmospheric pressure) the maximum rate enhancement ratio was 4.65. At low NO+H-2+Ar flow rate (17 mL/min; 17...

A Gas Chromatographic System for the Detection of Ethylene Gas Using Ambient Air as a Carrier Gas.

Science.gov (United States)

Zaidi, Nayyer Abbas; Tahir, Muhammad Waseem; Vellekoop, Michael J; Lang, Walter

2017-10-07

Ethylene gas is a naturally occurring gas that has an influence on the shelf life of fruit during their transportation in cargo ships. An unintentional exposure of ethylene gas during transportation results in a loss of fruit. A gas chromatographic system is presented here for the detection of ethylene gas. The gas chromatographic system was assembled using a preconcentrator, a printed 3D printed gas chromatographic column, a humidity sensor, solenoid valves, and an electrochemical ethylene gas sensor. Ambient air was used as a carrier gas in the gas chromatographic system. The flow rate was fixed to 10 sccm. It was generated through a mini-pump connected in series with a mass flow controller. The metal oxide gas sensor is discussed with its limitation in ambient air. The results show the chromatogram obtained from metal oxide gas sensor has low stability, drifts, and has uncertain peaks, while the chromatogram from the electrochemical sensor is stable and precise. Furthermore, ethylene gas measurements at higher ppb concentration and at lower ppb concentration were demonstrated with the electrochemical ethylene gas sensor. The system separates ethylene gas and humidity. The chromatograms obtained from the system are stable, and the results are 1.2% repeatable in five similar measurements. The statistical calculation of the gas chromatographic system shows that a concentration of 2.3 ppb of ethylene gas can be detected through this system.

Design considerations for teleoperation systems operating in gas-tight argon cells

Directory of Open Access Journals (Sweden)

Seungnam Yu

2017-12-01

Full Text Available In the nuclear industry, mechanical engineers spend a significant portion of their time designing equipment such as manipulators, bogies, mechanical grippers, and so on. Some customized designs can be considered as standard mechanical equipment in this area, although it is not unusual to find that an existing design cannot simply be copied from one project to another. Varied performance requirements can dictate that redesign, often quite extensive redesign, is required. However, if something similar has been done before, engineers could use that as a starting point for the new project. In this regard, this study presents several guidelines inspired by previous design knowledge for similar development cases. Moreover, this study presents more detailed suggestions such as design guidelines for an argon-based hot cell atmosphere and design experience for a large-scale practical hot cell facility. Design considerations and case studies dealt with in this study are dedicated to teleoperation manipulators that are used at a large-scale argon cell facility for pyroprocess integrated inactive demonstration (PRIDE, at the Korea Atomic Energy Research Institute. In particular, for case studies to support the suggested recommendations, a fabricated telemanipulator system for PRIDE is introduced, and several kinds of experimental results associated with it are presented.

Electrochemical thermodynamic measurement system

Science.gov (United States)

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

2009-09-29

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.

Electrochemical energy conversion: methanol fuel cell as example

Directory of Open Access Journals (Sweden)

Vielstich Wolf

2003-01-01

Full Text Available Thermodynamic and kinetic limitations of the electrochemical energy conversion are presented for the case of a methanol/oxygen fuel cell. The detection of intermediates and products is demonstrated using insitu FTIR spectroscopy and online mass spectrometry. The bifunctional catalysis of methanol oxydation by PtRu model surfaces is explained. The formation of HCOOH and HCHO via parallel reaction pathways is discussed. An example of DMFC system technology is presented.

Electrochemical deposition of buried contacts in high-efficiency crystalline silicon photovoltaic cells

DEFF Research Database (Denmark)

Jensen, Jens Arne Dahl; Møller, Per; Bruton, Tim

2003-01-01

This article reports on a newly developed method for electrochemical deposition of buried Cu contacts in Si-based photovoltaic ~PV! cells. Contact grooves, 20 mm wide by 40 mm deep, were laser-cut into Si PV cells, hereafter applied with a thin electroless NiP base and subsequently filled with Cu...... by electrochemical deposition at a rate of up to 10 mm per min. With the newly developed process, void-free, superconformal Cu-filling of the laser-cut grooves was observed by scanning electron microscopy and focused ion beam techniques. The Cu microstructure in grooves showed both bottom and sidewall texture......, with a grain-size decreasing from the center to the edges of the buried Cu contacts and a pronounced lateral growth outside the laser-cut grooves. The measured specific contact resistances of the buried contacts was better than the production standard. Overall performance of the new PV cells was equal...

Dependence of the constitution, microstructure and electrochemical behaviour of magnetron sputtered Li-Ni-Mn-Co-O thin film cathodes for lithium-ion batteries on the working gas pressure and annealing conditions

International Nuclear Information System (INIS)

Strafela, Marc; Fischer, Julian; Leiste, Harald; Rinke, Monika; Bergfeldt, Thomas; Seifert, Hans Juergen; Ulrich, Sven; Music, Denis; Chang, Keke; Schneider, Jochen

2017-01-01

Li(Ni 1/3 Mn 1/3 Co 1/3 )O 2 as a cathode material for lithium ion batteries shows good thermal stability, high reversible capacity (290 mAh g -1 ), good rate capability and better results in terms of environmental friendliness. In this paper thin film cathodes in the material system Li-Ni-Mn-Co-O were deposited onto silicon and stainless steel substrates, by non-reactive r.f. magnetron sputtering from a ceramic Li 1.18 (Ni 0.39 Mn 0.19 Co 0.35 )O 1.97 target at various argon working gas pressures between 0.2 Pa and 20 Pa. A comprehensive study on the composition and microstructure was carried out. The results showed that the elemental composition varies depending on argon working gas pressure. The elemental composition was determined by inductively coupled plasma optical emission spectroscopy in combination with carrier gas hot extraction. The films showed different grain orientations depending argon working gas pressures. The degree of cation order in the lattice structure of the films deposited at 0.5 Pa and 7 Pa argon working gas pressure, was increased by annealing in an argon/oxygen atmosphere at different pressures for one hour. The microstructure of the films varies with annealing gas pressure and is characterized using X-ray diffraction and unpolarized micro-Raman spectroscopy at room temperature. Electrochemical characterization of as-deposited and annealed films was carried out by galvanostatic cycling in Li-Ni-Mn-Co-O half-cells against metallic lithium. Correlations between process parameters, constitution, microstructure and electrochemical behaviour are discussed in detail.

Low temperature electrochemical cells with sodium β″-alumina solid electrolyte (BASE)

Science.gov (United States)

Girija, T. C.; Virkar, Anil V.

Cells of Daniell-type with copper-zinc electrochemical couples and sodium β″-alumina solid electrolyte (BASE) were constructed. The cathode consisted of copper in contact with its ions (Cu/Cu 2+) while zinc in contact with its ions (Zn/Zn 2+) constituted the anode. Dimethyl sulfoxide (DMSO) containing 1 M NaBF 4 was used as the liquid electrolyte. The configuration of the cell constructed can be written as follows: Zn(s)/ZnCl 2(DMSO)(0.1 M), NaBF 4(1 M)/BASE/NaBF 4(1 M), CuCl 2(DMSO)(0.1 M)/Cu(s). The cell was subjected to charge-discharge cycles at 100 °C. The BASE discs were found to be stable even after the cell was subjected to several electrochemical charge-discharge cycles. Cells were also constructed using BASE discs with porous BASE surface layers introduced to lower the interfacial resistance. Cells with surface modified BASE exhibited a lower resistance in comparison to those using unmodified BASE. XRD and SEM analyses indicated that no detectable degradation of BASE discs occurred after cell testing. Preliminary cell tests were also conducted with NaCF 3SO 3 in place of NaBF 4.

Downregulation of tight junction-associated MARVEL protein marvelD3 during epithelial-mesenchymal transition in human pancreatic cancer cells.

Science.gov (United States)

Kojima, Takashi; Takasawa, Akira; Kyuno, Daisuke; Ito, Tatsuya; Yamaguchi, Hiroshi; Hirata, Koichi; Tsujiwaki, Mitsuhiro; Murata, Masaki; Tanaka, Satoshi; Sawada, Norimasa

2011-10-01

The novel tight junction protein marvelD3 contains a conserved MARVEL (MAL and related proteins for vesicle trafficking and membrane link) domain like occludin and tricellulin. However, little is yet known about the detailed role and regulation of marvelD3 in normal epithelial cells and cancer cells, including pancreatic cancer. In the present study, we investigated marvelD3 expression in well and poorly differentiated human pancreatic cancer cell lines and normal pancreatic duct epithelial cells in which the hTERT gene was introduced into human pancreatic duct epithelial cells in primary culture, and the changes of marvelD3 during Snail-induced epithelial-mesenchymal transition (EMT) under hypoxia, TGF-β treatment and knockdown of FOXA2 in well differentiated pancreatic cancer HPAC cells. MarvelD3 was transcriptionally downregulated in poorly differentiated pancreatic cancer cells and during Snail-induced EMT of pancreatic cancer cells in which Snail was highly expressed and the fence function downregulated, whereas it was maintained in well differentiated human pancreatic cancer cells and normal pancreatic duct epithelial cells. Depletion of marvelD3 by siRNAs in HPAC cells resulted in downregulation of barrier functions indicated as a decrease in transepithelial electric resistance and an increase of permeability to fluorescent dextran tracers, whereas it did not affect fence function of tight junctions. In conclusion, marvelD3 is transcriptionally downregulated in Snail-induced EMT during the progression for the pancreatic cancer. Copyright © 2011 Elsevier Inc. All rights reserved.

Less-Tight versus Tight Control of Hypertension in Pregnancy

NARCIS (Netherlands)

Magee, Laura A.; von Dadelszen, Peter; Rey, Evelyne; Ross, Susan; Asztalos, Elizabeth; Murphy, Kellie E.; Menzies, Jennifer; Sanchez, Johanna; Singer, Joel; Gafni, Amiram; Gruslin, Andrée; Helewa, Michael; Hutton, Eileen; Lee, Shoo K.; Lee, Terry; Logan, Alexander G.; Ganzevoort, Wessel; Welch, Ross; Thornton, Jim G.; Moutquin, Jean-Marie

2015-01-01

BACKGROUND The effects of less-tight versus tight control of hypertension on pregnancy complications are unclear. METHODS We performed an open, international, multicenter trial involving women at 14 weeks 0 days to 33 weeks 6 days of gestation who had nonproteinuric preexisting or gestational

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

Directory of Open Access Journals (Sweden)

Nadav Ben-Dov

Full Text Available 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.

Formation of tilted clusters in the electrochemical deposition of copper on n-gas(001)

DEFF Research Database (Denmark)

Smilgies, D.M.; Feidenhans'l, Robert Krarup; Scherb, G.

1996-01-01

Using in-situ synchrotron X-ray diffraction, we have studied the epitaxial properties of Cu clusters electrochemically deposited on n-GaAs(001) substrates. The Cu clusters have (001) base planes and their [100] directions are aligned with the [110] directions of the GaAs(001) surface unit cell, b...

High performance reversible electrochemical cell for H2O electrolysis or conversion of CO2 and H2O to fuel

DEFF Research Database (Denmark)

2013-01-01

The present invention relates to a reversible electrochemical cell, such as an electrolysis cell for water splitting or for conversion of carbon dioxide and water into fuel. The present invention relates also to an electrochemical cell that when operated in reverse performs as a fuel cell...

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

Science.gov (United States)

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

2010-07-20

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.

Evaluation of gas-sensing properties of ZnO nanostructures electrochemically doped with Au nanophases

Directory of Open Access Journals (Sweden)

Elena Dilonardo

2016-01-01

Full Text Available A one-step electrochemical method based on sacrificial anode electrolysis (SAE was used to deposit stabilized gold nanoparticles (Au NPs directly on the surface of nanostructured ZnO powders, previously synthesized through a sol–gel process. The effect of thermal annealing temperatures (300 and 550 °C on chemical, morphological, and structural properties of pristine and Au-doped ZnO nancomposites (Au@ZnO was investigated. Transmission and scanning electron microscopy (TEM and SEM, as well as X-ray photoelectron spectroscopy (XPS, revealed the successful deposition of nanoscale gold on the surface of spherical and rod-like ZnO nanostructures, obtained after annealing at 300 and 550 °C, respectively. The pristine ZnO and Au@ZnO nanocomposites are proposed as active layer in chemiresistive gas sensors for low-cost processing. Gas-sensing measurements towards NO2 were collected at 300 °C, evaluating not only the Au-doping effect, but also the influence of the different ZnO nanostructures on the gas-sensing properties.

Method of preparing an electrochemical cell in uncharged state

Science.gov (United States)

Shimotake, Hiroshi; Bartholme, Louis G.; Arntzen, John D.

1977-02-01

A secondary electrochemical cell is assembled in an uncharged state for the preparation of a lithium alloy-transition metal sulfide cell. The negative electrode includes a material such as aluminum or silicon for alloying with lithium as the cell is charged. The positive electrode is prepared by blending particulate lithium sulfide, transition metal powder and electrolytic salt in solid phase. The mixture is simultaneously heated to a temperature in excess of the melting point of the electrolyte and pressed onto an electrically conductive substrate to form a plaque. The plaque is assembled as a positive electrode within the cell. During the first charge cycle lithium alloy is formed within the negative electrode and transition metal sulfide such as iron sulfide is produced within the positive electrode.

Electrochemical characterization of a polybenzimidazole-based high temperature proton exchange membrane unit cell

DEFF Research Database (Denmark)

Jespersen, Jesper Lebæk; Schaltz, Erik; Kær, Søren Knudsen

2009-01-01

This work constitutes detailed EIS (Electrochemical Impedance Spectroscopy) measurements on a PBIbased HT-PEM unit cell. By means of EIS the fuel cell is characterized in several modes of operation by varying the current density, temperature and the stoichiometry of the reactant gases. Using...

Tumor necrosis factor alpha increases epithelial barrier permeability by disrupting tight junctions in Caco-2 cells

Directory of Open Access Journals (Sweden)

W. Cui

2010-04-01

Full Text Available The objectives of this study were to determine the effect of tumor necrosis factor alpha (TNF-α on intestinal epithelial cell permeability and the expression of tight junction proteins. Caco-2 cells were plated onto Transwell® microporous filters and treated with TNF-α (10 or 100 ng/mL for 0, 4, 8, 16, or 24 h. The transepithelial electrical resistance and the mucosal-to-serosal flux rates of the established paracellular marker Lucifer yellow were measured in filter-grown monolayers of Caco-2 intestinal cells. The localization and expression of the tight junction protein occludin were detected by immunofluorescence and Western blot analysis, respectively. SYBR-Green-based real-time PCR was used to measure the expression of occludin mRNA. TNF-α treatment produced concentration- and time-dependent decreases in Caco-2 transepithelial resistance and increases in transepithelial permeability to the paracellular marker Lucifer yellow. Western blot results indicated that TNF-α decreased the expression of phosphorylated occludin in detergent-insoluble fractions but did not affect the expression of non-phosphorylated occludin protein. Real-time RT-PCR data showed that TNF-α did not affect the expression of occludin mRNA. Taken together, our data demonstrate that TNF-α increases Caco-2 monolayer permeability, decreases occludin protein expression and disturbs intercellular junctions.

Development of a spectro-electrochemical cell for soft X-ray photon-in photon-out spectroscopy

Science.gov (United States)

Ishihara, Tomoko; Tokushima, Takashi; Horikawa, Yuka; Kato, Masaru; Yagi, Ichizo

2017-10-01

We developed a spectro-electrochemical cell for X-ray absorption and X-ray emission spectroscopy, which are element-specific methods to study local electronic structures in the soft X-ray region. In the usual electrochemical measurement setup, the electrode is placed in solution, and the surface/interface region of the electrode is not normally accessible by soft X-rays that have low penetration depth in liquids. To realize soft X-ray observation of electrochemical reactions, a 15-nm-thick Pt layer was deposited on a 150-nm-thick film window with an adhesive 3-nm-thick Ti layer for use as both the working electrode and the separator window between vacuum and a sample liquid under atmospheric pressure. The designed three-electrode electrochemical cell consists of a Pt film on a SiC window, a platinized Pt wire, and a commercial Ag|AgCl electrode as the working, counter, and reference electrodes, respectively. The functionality of the cell was tested by cyclic voltammetry and X-ray absorption and emission spectroscopy. As a demonstration, the electroplating of Pb on the Pt/SiC membrane window was measured by X-ray absorption and real-time monitoring of fluorescence intensity at the O 1s excitation.

An Electrochemical Impedance Spectroscopy Study on a Lithium Sulfur Pouch Cell

DEFF Research Database (Denmark)

Stroe, Daniel Loan; Knap, Vaclav; Swierczynski, Maciej Jozef

2016-01-01

The impedance behavior of a 3.4 Ah pouch Lithium-Sulfur cell was extensively characterized using the electrochemical impedance spectroscopy (EIS) technique. EIS measurements were performed at various temperatures and over the entire state-of-charge (SOC) interval without applying a superimposed DC...

Integrating Microbial Electrochemical Technology with Forward Osmosis and Membrane Bioreactors: Low-Energy Wastewater Treatment, Energy Recovery and Water Reuse

KAUST Repository

Werner, Craig M.

2014-06-01

treatment process. The anaerobic electrochemical membrane bioreactor described here integrates a microbial electrolysis cell with a membrane bioreactor using conductive hollow fiber membrane to produce hydrogen gas, treat wastewater and reclaim treated water. The energy recovered as hydrogen gas in this system was sufficient to offset all the electrical energy requirements for operation. The findings from these studies significantly improve the prospects for simultaneous wastewater treatment, energy recovery and water reclamation in a single reactor but challenges such as membrane biofouling and conversion of hydrogen to methane by methanogenesis require further study.

Quantum Dot Nanotoxicity Investigations Using Human Lung Cells and TOXOR Electrochemical Enzyme Assay Methodology.

Science.gov (United States)

O'Hara, Tony; Seddon, Brian; O'Connor, Andrew; McClean, Siobhán; Singh, Baljit; Iwuoha, Emmanuel; Fuku, Xolile; Dempsey, Eithne

2017-01-27

Recent studies have suggested that certain nanomaterials can interfere with optically based cytotoxicity assays resulting in underestimations of nanomaterial toxicity. As a result there has been growing interest in the use of whole cell electrochemical biosensors for nanotoxicity applications. Herein we report application of an electrochemical cytotoxicity assay developed in house (TOXOR) in the evaluation of toxic effects of mercaptosuccinic acid capped cadmium telluride quantum dots (MSA capped CdTe QDs), toward mammalian cells. MSA capped CdTe QDs were synthesized, characterized, and their cytotoxicity toward A549 human lung epithelial cells investigated. The internalization of QDs within cells was scrutinized via confocal microscopy. The cytotoxicity assay is based on the measurement of changes in cellular enzyme acid phosphatase upon 24 h exposure to QDs. Acid phosphatase catalyzes dephosphorylation of 2-naphthyl phosphate to 2-naphthol (determined by chronocoulometry) and is indicative of metabolic activity in cells. The 24 h IC50 (concentration resulting in 50% reduction in acid phosphatase activity) value for MSA capped CdTe QDs was found to be 118 ± 49 μg/mL using the TOXOR assay and was in agreement with the MTT assay (157 ± 31 μg/mL). Potential uses of this electrochemical assay include the screening of nanomaterials, environmental toxins, in addition to applications in the pharmaceutical, food, and health sectors.

Electrochemical behaviour and nanoscale characteristics of CNT-based fibers as new substrate for cell growth

Energy Technology Data Exchange (ETDEWEB)

Polizu, S.; Yahia, L.H. [Ecole Polytechnique de Montreal, PQ (Canada). Laboratoire d' innovation et d' analyse de la bioperformance; Savadogo, O. [Ecole Polytechnique de Montreal, Montreal, PQ (Canada). Laboratoire de nouveaux materiaux pour l' energie et l' electrochimie; Maugey, M.; Poulin, P. [Centre de Recherche Paul Pascal, CNRS, Bordeaux (France); Rouabhia, M. [Laval Univ., Quebec City, PQ (Canada). Faculty of Medicine

2008-07-01

This paper reported on a study in which carbon nanotube (CNT) macroscopic fibers were formulated by a newly developed non-covalent method for fabricating fibrous substrate. The covalent and noncovalent chemistry of CNTs has been widely used in the development of CNT-based biomaterials as active substrates for living cells. Time of Flight Mass Spectroscopy (TOF-SIMS) analysis was used to determine the surface characteristics of the CNT-based fibers produced by wet spinning method. The structure and texture of fibers were imaged using Low-Vacuum Scanning Electron Microscopy (LV-SEM) equipped with an Energy Dispersive Spectrometer (EDS) for microanalysis. Atomic Force Microscopy (AFM) imaging revealed the structure of fibers. Cyclic Voltametry (CV) measurements were performed to examine the electrochemical behaviour of fibers. Sulfuric acid and a cell culture medium was used as the 2 different electrolytes. The influences of environmental parameters on the electrochemical phenomena taking place were identified. The intrinsic electrochemical characteristics of fibers were revealed through measurements in acid environment. The cell culture medium simulated the physiological conditions. It was concluded that the newly developed wet spinning method is very efficient for making CNT-based fibers as electroactive biomaterials. The structural nanoscale details evidenced a good alignment of nanotubes in the thread and the critical role it plays in electrochemical interactions. The differences induced by the variation of electrolytes suggest that a relationship could be established between the fiber chemistry and the electrochemical response. This correlation has considerably potential for the design of new biomedical devices. 2 refs.

Electrochemical solar energy conversion

International Nuclear Information System (INIS)

Gerischer, H.

1991-01-01

The principles of solar energy conversion in photoelectrochemical cells are briefly reviewed. Cells for the generation of electric power and for energy storage in form of electrochemical energy are described. These systems are compared with solid state photovoltaic devices, and the inherent difficulties for the operation of the electrochemical systems are analyzed. (author). 28 refs, 10 figs

Development of a new quantitative gas permeability method for dental implant-abutment connection tightness assessment

Science.gov (United States)

2011-01-01

Background Most dental implant systems are presently made of two pieces: the implant itself and the abutment. The connection tightness between those two pieces is a key point to prevent bacterial proliferation, tissue inflammation and bone loss. The leak has been previously estimated by microbial, color tracer and endotoxin percolation. Methods A new nitrogen flow technique was developed for implant-abutment connection leakage measurement, adapted from a recent, sensitive, reproducible and quantitative method used to assess endodontic sealing. Results The results show very significant differences between various sealing and screwing conditions. The remaining flow was lower after key screwing compared to hand screwing (p = 0.03) and remained different from the negative test (p = 0.0004). The method reproducibility was very good, with a coefficient of variation of 1.29%. Conclusions Therefore, the presented new gas flow method appears to be a simple and robust method to compare different implant systems. It allows successive measures without disconnecting the abutment from the implant and should in particular be used to assess the behavior of the connection before and after mechanical stress. PMID:21492459

A methodology for thermodynamic simulation of high temperature, internal reforming fuel cell systems

Science.gov (United States)

Matelli, José Alexandre; Bazzo, Edson

This work presents a methodology for simulation of fuel cells to be used in power production in small on-site power/cogeneration plants that use natural gas as fuel. The methodology contemplates thermodynamics and electrochemical aspects related to molten carbonate and solid oxide fuel cells (MCFC and SOFC, respectively). Internal steam reforming of the natural gas hydrocarbons is considered for hydrogen production. From inputs as cell potential, cell power, number of cell in the stack, ancillary systems power consumption, reformed natural gas composition and hydrogen utilization factor, the simulation gives the natural gas consumption, anode and cathode stream gases temperature and composition, and thermodynamic, electrochemical and practical efficiencies. Both energetic and exergetic methods are considered for performance analysis. The results obtained from natural gas reforming thermodynamics simulation show that the hydrogen production is maximum around 700 °C, for a steam/carbon ratio equal to 3. As shown in the literature, the found results indicate that the SOFC is more efficient than MCFC.

Gas transport in solid oxide fuel cells

CERN Document Server

He, Weidong; Dickerson, James

2014-01-01

This book provides a comprehensive overview of contemporary research and emerging measurement technologies associated with gas transport in solid oxide fuel cells. Within these pages, an introduction to the concept of gas diffusion in solid oxide fuel cells is presented. This book also discusses the history and underlying fundamental mechanisms of gas diffusion in solid oxide fuel cells, general theoretical mathematical models for gas diffusion, and traditional and advanced techniques for gas diffusivity measurement.

Low cost bipolar current collector-separator for electrochemical cells

International Nuclear Information System (INIS)

Lawrence, R.

1980-01-01

A bipolar current collecting, cell separating element for electrochemical cells for conducting current from the anode electrode of one cell unit to cathode electrode of the adjacent cell unit comprises: (A) a pressure mold aggregate of electrically conductive carbon/graphite particles and thermoplastic fluorocarbon polymer resin particles in a weight ratio of 2.5:1 to 16:1 whereby said molded aggregated has a bulk resistivity which is less than 4x10 -3 ohm/inch, (B) said molded aggregate having a fluid imprevious main body, at least one recessed chamber on one side of said main body and a plurality of spaced, conductive projections extending from the base of said chamber for contacting and permitting current flow between the electrode of adjacent cell unit, and (C) means communicating with said recessed chambers to permit introduction and removal of fluids

Microfabricated microbial fuel cell arrays reveal electrochemically active microbes.

Directory of Open Access Journals (Sweden)

Huijie Hou

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

Coating for lithium anode, thionyl chloride active cathode electrochemical cell

Energy Technology Data Exchange (ETDEWEB)

Catanzarite, V.O.

1983-01-04

Electrochemical power cells having a cathode current collector, a combination liquid active cathode depolarizer electrolyte solvent and an anode that forms surface compounds when in intimate contact with the liquid cathode are enhanced by the addition of a passivation limiting film contiguous to said anode. The passivating film is a member of the cyanoacrilate family of organic compounds.

Coating for lithium anode, thionyl chloride active cathode electrochemical cell

Energy Technology Data Exchange (ETDEWEB)

Catanzarite, V.O.

1981-10-20

Electrochemical power cells having a cathode current collector, a combination liquid active cathode depolarizer electrolyte solvent and an anode that forms surface compounds when in intimate contact with the liquid cathode are enhanced by the addition of a passivation limiting film contiguous to said anode. The passivating film is a member of the cyanoacrilate family of organic compounds.

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

Science.gov (United States)

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

2009-11-01

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

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

Science.gov (United States)

Lopes, F A; Perrin, S; Féron, D

2007-01-01

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.

Improving horizontal completions on heterogeneous tight shales

Energy Technology Data Exchange (ETDEWEB)

Suarez-Rivera, Roberto; Deenadayalu, Chaitanya; Chertov, Maxim; Novalo Hartanto, Ricardo; Gathogo, Patrick [Schlumberger (United States); Kunjir, Rahul [University of Utah (United States)

2011-07-01

Evaluation of the two formation characteristics conducive to economic well production is important when tight shale formation characterization and completion design are being considered. This paper presents the basic understanding required to improve the efficiency of horizontal completions in oil and gas producing shales. Guidelines are defined for effective perforation and fracturing to improve the efficiency and sustainability of horizontal completions using extensive laboratory characterization of mechanical properties on core, core/log integration and continuous mapping of these properties by logging-while-drilling (LWD) methods. The objective is to improve completion design efficiency. This is accomplished by suitable selection of perforation intervals based on an understanding of the relevant physical processes and rock characterization. Conditions at two reservoir regions, the near-wellbore and the far-wellbore, are outlined and are essential to completion design. From the study, it can be concluded that tight shales are strongly anisotropic and cannot be approximated using isotropic models.

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

Science.gov (United States)

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

2004-01-01

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

Dependence of the constitution, microstructure and electrochemical behaviour of magnetron sputtered Li-Ni-Mn-Co-O thin film cathodes for lithium-ion batteries on the working gas pressure and annealing conditions

Energy Technology Data Exchange (ETDEWEB)

Strafela, Marc; Fischer, Julian; Leiste, Harald; Rinke, Monika; Bergfeldt, Thomas; Seifert, Hans Juergen; Ulrich, Sven [Karlsruhe Institute of Technology (KIT), Karlsruhe (Germany). Inst. for Applied Materials (IAM); Music, Denis; Chang, Keke; Schneider, Jochen [RWTH Aachen Univ. (Germany). Materials Chemistry

2017-11-15

Li(Ni{sub 1/3}Mn{sub 1/3}Co{sub 1/3})O{sub 2} as a cathode material for lithium ion batteries shows good thermal stability, high reversible capacity (290 mAh g{sup -1}), good rate capability and better results in terms of environmental friendliness. In this paper thin film cathodes in the material system Li-Ni-Mn-Co-O were deposited onto silicon and stainless steel substrates, by non-reactive r.f. magnetron sputtering from a ceramic Li{sub 1.18}(Ni{sub 0.39}Mn{sub 0.19}Co{sub 0.35})O{sub 1.97} target at various argon working gas pressures between 0.2 Pa and 20 Pa. A comprehensive study on the composition and microstructure was carried out. The results showed that the elemental composition varies depending on argon working gas pressure. The elemental composition was determined by inductively coupled plasma optical emission spectroscopy in combination with carrier gas hot extraction. The films showed different grain orientations depending argon working gas pressures. The degree of cation order in the lattice structure of the films deposited at 0.5 Pa and 7 Pa argon working gas pressure, was increased by annealing in an argon/oxygen atmosphere at different pressures for one hour. The microstructure of the films varies with annealing gas pressure and is characterized using X-ray diffraction and unpolarized micro-Raman spectroscopy at room temperature. Electrochemical characterization of as-deposited and annealed films was carried out by galvanostatic cycling in Li-Ni-Mn-Co-O half-cells against metallic lithium. Correlations between process parameters, constitution, microstructure and electrochemical behaviour are discussed in detail.

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

Energy Technology Data Exchange (ETDEWEB)

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

2011-09-14

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.

Identification of MarvelD3 as a tight junction-associated transmembrane protein of the occludin family

Directory of Open Access Journals (Sweden)

Balda Maria S

2009-12-01

Full Text Available Abstract Background Tight junctions are an intercellular adhesion complex of epithelial and endothelial cells, and form a paracellular barrier that restricts the diffusion of solutes on the basis of size and charge. Tight junctions are formed by multiprotein complexes containing cytosolic and transmembrane proteins. How these components work together to form functional tight junctions is still not well understood and will require a complete understanding of the molecular composition of the junction. Results Here we identify a new transmembrane component of tight junctions: MarvelD3, a four-span transmembrane protein. Its predicted transmembrane helices form a Marvel (MAL and related proteins for vesicle traffic and membrane link domain, a structural motif originally discovered in proteins involved in membrane apposition and fusion events, such as the tight junction proteins occludin and tricellulin. In mammals, MarvelD3 is expressed as two alternatively spliced isoforms. Both isoforms exhibit a broad tissue distribution and are expressed by different types of epithelial as well as endothelial cells. MarvelD3 co-localises with occludin at tight junctions in intestinal and corneal epithelial cells. RNA interference experiments in Caco-2 cells indicate that normal MarvelD3 expression is not required for the formation of functional tight junctions but depletion results in monolayers with increased transepithelial electrical resistance. Conclusions Our data indicate that MarvelD3 is a third member of the tight junction-associated occludin family of transmembrane proteins. Similar to occludin, normal expression of MarvelD3 is not essential for the formation of functional tight junctions. However, MarvelD3 functions as a determinant of epithelial paracellular permeability properties.

Gas-Phase Functionalization of Macroscopic Carbon Nanotube Fiber Assemblies: Reaction Control, Electrochemical Properties, and Use for Flexible Supercapacitors.

Science.gov (United States)

Iglesias, Daniel; Senokos, Evgeny; Alemán, Belén; Cabana, Laura; Navío, Cristina; Marcilla, Rebeca; Prato, Maurizio; Vilatela, Juan J; Marchesan, Silvia

2018-02-14

The assembly of aligned carbon nanotubes (CNTs) into fibers (CNTFs) is a convenient approach to exploit and apply the unique physico-chemical properties of CNTs in many fields. CNT functionalization has been extensively used for its implementation into composites and devices. However, CNTF functionalization is still in its infancy because of the challenges associated with preservation of CNTF morphology. Here, we report a thorough study of the gas-phase functionalization of CNTF assemblies using ozone which was generated in situ from a UV source. In contrast with liquid-based oxidation methods, this gas-phase approach preserves CNTF morphology, while notably increasing its hydrophilicity. The functionalized material is thoroughly characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, and scanning electron microscopy. Its newly acquired hydrophilicity enables CNTF electrochemical characterization in aqueous media, which was not possible for the pristine material. Through comparison of electrochemical measurements in aqueous electrolytes and ionic liquids, we decouple the effects of functionalization on pseudocapacitive reactions and quantum capacitance. The functionalized CNTF assembly is successfully used as an active material and a current collector in all-solid supercapacitor flexible devices with an ionic liquid-based polymer electrolyte.

Field-Assisted Splitting of Pure Water Based on Deep-Sub-Debye-Length Nanogap Electrochemical Cells.

Science.gov (United States)

Wang, Yifei; Narayanan, S R; Wu, Wei

2017-08-22

Owing to the low conductivity of pure water, using an electrolyte is common for achieving efficient water electrolysis. In this paper, we have fundamentally broken through this common sense by using deep-sub-Debye-length nanogap electrochemical cells to achieve efficient electrolysis of pure water (without any added electrolyte) at room temperature. A field-assisted effect resulted from overlapped electrical double layers can greatly enhance water molecules ionization and mass transport, leading to electron-transfer limited reactions. We have named this process "virtual breakdown mechanism" (which is completely different from traditional mechanisms) that couples the two half-reactions together, greatly reducing the energy losses arising from ion transport. This fundamental discovery has been theoretically discussed in this paper and experimentally demonstrated in a group of electrochemical cells with nanogaps between two electrodes down to 37 nm. On the basis of our nanogap electrochemical cells, the electrolysis current density from pure water can be significantly larger than that from 1 mol/L sodium hydroxide solution, indicating the much better performance of pure water splitting as a potential for on-demand clean hydrogen production.

Development of remote electrochemical decontamination for hot cell applications

International Nuclear Information System (INIS)

Turner, A.D.; Lain, M.J.; Fletcher, P.A.; Dawson, R.K.; Pottinger, J.S.

1989-01-01

The primary aim of the programme is to develop and evaluate remote electrochemical decontamination systems for metal surfaces. The bulk of the waste volume should be reduced to a reuse or low-level waste disposal category, while concentrating most of the activity in a small volume suitable for immobilisation. The goal of the development programme is to test these techniques in both alpha-active and alpha-beta-gamma hot cells in order to ascertain their usefulness as a component of an overall decommissioning strategy. As a result of the radiological environment, particular emphasis will be placed on remote operation in order to reduce occupational radiation exposure. Two types of technique based on the electrochemical dissolution of thin surface layers of the substrate will be investigated: immersion of small items in tanks for electroetching and in situ electropolishing. In both cases, reagents will be chosen with their subsequent disposal in mind. (Author)

Tightness and suitability evaluation of abandoned salt caverns served as hydrocarbon energies storage under adverse geological conditions (AGC)

International Nuclear Information System (INIS)

Wei, Liu; Jie, Chen; Deyi, Jiang; Xilin, Shi; Yinping, Li; Daemen, J.J.K.; Chunhe, Yang

2016-01-01

Highlights: • Tightness conditions are set to assess use of old caverns for hydrocarbons storage. • Gas seepage and tightness around caverns are numerically simulated under AGC. • κ of interlayers act as a key factor to affect the tightness and use of salt cavern. • The threshold upper permeability of interlayers is proposed for storing oil and gas. • Three types of real application are introduced by using the tightness conditions. - Abstract: In China, the storage of hydrocarbon energies is extremely insufficient partially due to the lack of storage space, but on the other side the existence of a large number of abandoned salt caverns poses a serious threat to safety and geological environments. Some of these caverns, defined as abandoned caverns under adverse geological conditions (AGC), are expected to store hydrocarbon energies (natural gas or crude oil) to reduce the risk of potential disasters and simultaneously support the national strategic energy reserve of China. Herein, a series of investigations primarily related to the tightness and suitability of the caverns under AGC is performed. Laboratory measurements to determine the physical and mechanical properties as well as porosity and permeability of bedded salt cores from a near target cavern are implemented to determine the petro-mechanical properties and basic parameters for further study. The results show that the mechanical properties of the bedded rock salts are satisfactory for the stability of caverns. The interface between the salt and interlayers exhibits mechanical properties that are between those of rock salt and interlayers and in particular is not a weak zone. The silty mudstone interlayers have relatively high porosity and permeability, likely due to their low content of clay minerals and the presence of halite-filled cracks. The conditions for evaluating the tightness and suitability of a cavern for storing hydrocarbons are proposed, including “No tensile stress,” �

A Molecularly Imprinted Electrochemical Gas Sensor to Sense Butylated Hydroxytoluene in Air

Directory of Open Access Journals (Sweden)

Shadi Emam

2018-01-01

Full Text Available Alzheimer’s disease (AD is a neurodegenerative disease, which affects millions of people worldwide. Curing this disease has not gained much success so far. Exhaled breath gas analysis offers an inexpensive, noninvasive, and immediate method for detecting a large number of diseases, including AD. In this paper, a new method is proposed to detect butylated hydroxytoluene (BHT in the air, which is one of the chemicals found in the breath print of AD patients. A three-layer sensor was formed through deposition of a thin layer of graphene onto a glassy carbon substrate. Selective binding of the analyte was facilitated by electrochemically initiated polymerization of a solution containing the desired target molecule. Subsequent polymerization and removal of the analyte yielded a layer of polypyrrole, a conductive polymer, on top of the sensor containing molecularly imprinted cavities selective for the target molecule. Two sets of sensors have been developed. First, the graphene sensor has been fabricated with a layer of reduced graphene oxide (RGO and tested over 5–100 part per million (ppm. For the second batch, Prussian blue was added to graphene before polymerization, mainly for enhancing the electrochemical properties. The sensor was tested over 0.02-1 parts per billion (ppb level of concentration while the sensor resistance has been monitored.

Analysis of transport phenomena and electrochemical reactions in a micro PEM fuel cell

Energy Technology Data Exchange (ETDEWEB)

Sadiq Al-Baghdadi, Maher A.R. [Fuel Cell Research Center, International Energy and Environment Foundation, Najaf, P.O.Box 39 (Iraq)

2013-07-01

Micro-fuel cells are considered as promising electrochemical power sources in portable electronic devices. The presence of microelectromechanical system (MEMS) technology makes it possible to manufacture the miniaturized fuel cell systems. The majority of research on micro-scale fuel cells is aimed at micro-power applications. Performance of micro-fuel cells are closely related to many factors, such as designs and operating conditions. CFD modeling and simulation for heat and mass transport in micro PEM fuel cells are being used extensively in researches and industrial applications to gain better understanding of the fundamental processes and to optimize the micro fuel cell designs before building a prototype for engineering application. In this research, full three-dimensional, non-isothermal computational fluid dynamics model of a micro proton exchange membrane (PEM) fuel cell has been developed. This comprehensive model accounts for the major transport phenomena such as convective and diffusive heat and mass transfer, electrode kinetics, transport and phase-change mechanism of water, and potential fields in a micro PEM fuel cell. The model explains many interacting, complex electrochemical, and transport phenomena that cannot be studied experimentally. Three-dimensional results of the species profiles, temperature distribution, potential distribution, and local current density distribution are presented and analysed, with the focus on the physical insight and fundamental understanding.

Low temperature electrochemical cells with sodium {beta}''-alumina solid electrolyte (BASE)

Energy Technology Data Exchange (ETDEWEB)

Girija, T.C.; Virkar, Anil V. [Department of Materials Science and Engineering, 122 S. Central Campus Drive, University of Utah, Salt Lake City, UT 84112 (United States)

2008-05-15

Cells of Daniell-type with copper-zinc electrochemical couples and sodium {beta}''-alumina solid electrolyte (BASE) were constructed. The cathode consisted of copper in contact with its ions (Cu/Cu{sup 2+}) while zinc in contact with its ions (Zn/Zn{sup 2+}) constituted the anode. Dimethyl sulfoxide (DMSO) containing 1 M NaBF{sub 4} was used as the liquid electrolyte. The configuration of the cell constructed can be written as follows: Zn(s)/ZnCl{sub 2}(DMSO)(0.1 M), NaBF{sub 4}(1 M)/BASE/NaBF{sub 4}(1 M), CuCl{sub 2}(DMSO)(0.1 M)/Cu(s) The cell was subjected to charge-discharge cycles at 100 C. The BASE discs were found to be stable even after the cell was subjected to several electrochemical charge-discharge cycles. Cells were also constructed using BASE discs with porous BASE surface layers introduced to lower the interfacial resistance. Cells with surface modified BASE exhibited a lower resistance in comparison to those using unmodified BASE. XRD and SEM analyses indicated that no detectable degradation of BASE discs occurred after cell testing. Preliminary cell tests were also conducted with NaCF{sub 3}SO{sub 3} in place of NaBF{sub 4}. (author)

Time-dependent effects of low-temperature atmospheric-pressure argon plasma on epithelial cell attachment, viability and tight junction formation in vitro

International Nuclear Information System (INIS)

Hoentsch, Maxi; Barbara Nebe, J; Von Woedtke, Thomas; Weltmann, Klaus-Dieter

2012-01-01

The application of physical plasma to living tissues is expected to promote wound healing by plasma disinfection and stimulation of tissue regeneration. However, the effects of plasma on healthy cells must be studied and understood. In our experiments we used an argon plasma jet (kINPen®09) to gain insights into time-dependent plasma effects on cell attachment, viability and tight junction formation in vitro. Murine epithelial cells mHepR1 were suspended in complete cell culture medium and were irradiated with argon plasma (direct approach) for 30, 60 and 120 s. Suspecting that physical plasma may exert its effect via the medium, cell culture medium alone was first treated with argon plasma (indirect approach) and immediately afterwards, cells were added and also cultured for 24 h. Cell morphology and vitality were verified using light microscopy and an enzyme-linked immunosorbent assay. Already after 30 s of treatment the mHepR1 cells lost their capability to adhere and the cell vitality decreased with increasing treatment time. Interestingly, the same inhibitory effect was observed in the indirect approach. Furthermore, the argon plasma-treated culture medium-induced large openings of the cell's tight junctions, were verified by the zonula occludens protein ZO-1, which we observed for the first time in confluently grown epithelial cells. (paper)

Analysis of transport phenomena and electrochemical reactions in a micro PEM fuel cell

OpenAIRE

Maher A.R. Sadiq Al-Baghdadi

2014-01-01

Micro-fuel cells are considered as promising electrochemical power sources in portable electronic devices. The presence of microelectromechanical system (MEMS) technology makes it possible to manufacture the miniaturized fuel cell systems. The majority of research on micro-scale fuel cells is aimed at micro-power applications. Performance of micro-fuel cells are closely related to many factors, such as designs and operating conditions. CFD modeling and simulation for heat and mass transport i...

Multi-layer thin-film electrolytes for metal supported solid oxide fuel cells

Science.gov (United States)

Haydn, Markus; Ortner, Kai; Franco, Thomas; Uhlenbruck, Sven; Menzler, Norbert H.; Stöver, Detlev; Bräuer, Günter; Venskutonis, Andreas; Sigl, Lorenz S.; Buchkremer, Hans-Peter; Vaßen, Robert

2014-06-01

A key to the development of metal-supported solid oxide fuel cells (MSCs) is the manufacturing of gas-tight thin-film electrolytes, which separate the cathode from the anode. This paper focuses the electrolyte manufacturing on the basis of 8YSZ (8 mol.-% Y2O3 stabilized ZrO2). The electrolyte layers are applied by a physical vapor deposition (PVD) gas flow sputtering (GFS) process. The gas-tightness of the electrolyte is significantly improved when sequential oxidic and metallic thin-film multi-layers are deposited, which interrupt the columnar grain structure of single-layer electrolytes. Such electrolytes with two or eight oxide/metal layers and a total thickness of about 4 μm obtain leakage rates of less than 3 × 10-4 hPa dm3 s-1 cm-2 (Δp: 100 hPa) at room temperature and therefore fulfill the gas tightness requirements. They are also highly tolerant with respect to surface flaws and particulate impurities which can be present on the graded anode underground. MSC cell tests with double-layer and multilayer electrolytes feature high power densities more than 1.4 W cm-2 at 850 °C and underline the high potential of MSC cells.

Quasi-reference electrodes in confined electrochemical cells can result in in situ production of metallic nanoparticles.

Science.gov (United States)

Perera, Rukshan T; Rosenstein, Jacob K

2018-01-31

Nanoscale working electrodes and miniaturized electroanalytical devices are valuable platforms to probe molecular phenomena and perform chemical analyses. However, the inherent close distance of metallic electrodes integrated into a small volume of electrolyte can complicate classical electroanalytical techniques. In this study, we use a scanning nanopipette contact probe as a model miniaturized electrochemical cell to demonstrate measurable side effects of the reaction occurring at a quasi-reference electrode. We provide evidence for in situ generation of nanoparticles in the absence of any electroactive species and we critically analyze the origin, nucleation, dissolution and dynamic behavior of these nanoparticles as they appear at the working electrode. It is crucial to recognize the implications of using quasi-reference electrodes in confined electrochemical cells, in order to accurately interpret the results of nanoscale electrochemical experiments.

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

Science.gov (United States)

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

1981-07-29

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

Determination of Te in soldering tin using continuous flowing electrochemical hydride generation atomic fluorescence spectrometry

International Nuclear Information System (INIS)

Jiang Xianjuan; Gan Wuer; Han Suping; He Youzhao

2008-01-01

An electrochemical hydride generation system was developed for the detection of Te by coupling an electrochemical hydride generator with atomic fluorescence spectrometry. Since TeH 2 is unstable and easily decomposes in solution, a reticular W filament cathode was used in the present system. The TeH 2 generated on the cathode surface was effectively driven out by sweeping gas from the cathode chamber. In addition, a low temperature electrochemical cell (10 deg. C) was applied to reduce the decomposition of TeH 2 in solution. The limit of detection (LOD) was 2.2 ng ml -1 and the relative standard deviation (RSD) was 3.9% for nine consecutive measurements of standard solution. This method was successfully employed for determination of Te in soldering tin material

A Central Composite Face-Centered Design for Parameters Estimation of PEM Fuel Cell Electrochemical Model

Directory of Open Access Journals (Sweden)

Khaled MAMMAR

2013-11-01

Full Text Available In this paper, a new approach based on Experimental of design methodology (DoE is used to estimate the optimal of unknown model parameters proton exchange membrane fuel cell (PEMFC. This proposed approach combines the central composite face-centered (CCF and numerical PEMFC electrochemical. Simulation results obtained using electrochemical model help to predict the cell voltage in terms of inlet partial pressures of hydrogen and oxygen, stack temperature, and operating current. The value of the previous model and (CCF design methodology is used for parametric analysis of electrochemical model. Thus it is possible to evaluate the relative importance of each parameter to the simulation accuracy. However this methodology is able to define the exact values of the parameters from the manufacture data. It was tested for the BCS 500-W stack PEM Generator, a stack rated at 500 W, manufactured by American Company BCS Technologies FC.

Injection of Spin-Polarized Electrons into a AlGaN/GaN Device from an Electrochemical Cell: Evidence for an Extremely Long Spin Lifetime.

Science.gov (United States)

Kumar, Anup; Capua, Eyal; Fontanesi, Claudio; Carmieli, Raanan; Naaman, Ron

2018-04-24

Spin-polarized electrons are injected from an electrochemical cell through a chiral self-assembled organic monolayer into a AlGaN/GaN device in which a shallow two-dimensional electron gas (2DEG) layer is formed. The injection is monitored by a microwave signal that indicates a coherent spin lifetime that exceeds 10 ms at room temperature. The signal was found to be magnetic field independent; however, it depends on the current of the injected electrons, on the length of the chiral molecules, and on the existence of 2DEG.

Electrochemical Processes

DEFF Research Database (Denmark)

Bech-Nielsen, Gregers

1997-01-01

The notes describe in detail primary and secondary galvanic cells, fuel cells, electrochemical synthesis and electroplating processes, corrosion: measurments, inhibitors, cathodic and anodic protection, details of metal dissolution reactions, Pourbaix diagrams and purification of waste water from...

Electrochemical analysis

International Nuclear Information System (INIS)

Hwang, Hun

2007-02-01

This book explains potentiometry, voltametry, amperometry and basic conception of conductometry with eleven chapters. It gives the specific descriptions on electrochemical cell and its mode, basic conception of electrochemical analysis on oxidation-reduction reaction, standard electrode potential, formal potential, faradaic current and faradaic process, mass transfer and overvoltage, potentiometry and indirect potentiometry, polarography with TAST, normal pulse and deferential pulse, voltammetry, conductometry and conductometric titration.

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

KAUST Repository

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

2011-01-01

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 4. days, 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 52% at 6. weeks. Electrochemical performance followed the viable cell trend, with a positive correlation for power density and an inverse correlation for anode charge transfer resistance. The biofilm architecture shifted from rod-shaped, dispersed cells to more filamentous structures, with the continuous detection of Geobacter sulfurreducens-like 16S rRNA fragments throughout operation and the emergence of a community member related to a known phenazine-producing Pseudomonas species. A drop in cathode open circuit potential between weeks two and three suggested that uncontrolled biofilm growth on the cathode deleteriously affects system performance. © 2010 Elsevier Ltd.

Lecithin-Bound Iodine Prevents Disruption of Tight Junctions of Retinal Pigment Epithelial Cells under Hypoxic Stress

Directory of Open Access Journals (Sweden)

Masahiko Sugimoto

2016-01-01

Full Text Available Aim. We investigated whether lecithin-bound iodine (LBI can protect the integrity of tight junctions of retinal pigment epithelial cells from hypoxia. Method. Cultured human retinal pigment epithelial (ARPE-19 cells were pretreated with LBI. To mimic hypoxic conditions, cells were incubated with CoCl2. We compared the integrity of the tight junctions (TJs of control to cells with either LBI alone, CoCl2 alone, or LBI + CoCl2. The levels of cytokines in the conditioned media were also determined. Results. Significant decrease in the zonula occludens-1 (ZO-1 intensity in the CoCl2 group compared to the control (5787.7 ± 4126.4 in CoCl2 group versus 29244.6 ± 2981.2 in control; average ± standard deviation. But the decrease was not significant in the LBI + CoCl2 (27189.0 ± 11231.1. The levels of monocyte chemoattractant protein-1 (MCP-1 and Chemokine (C-C Motif Ligand 11 (CCL-11 were significantly higher in the CoCl2 than in the control (340.8 ± 43.3 versus 279.7 ± 68.3 pg/mL for MCP-1, and 15.2 ± 12.9 versus 12.5 ± 6.1 pg/mL for CCL-11. With LBI pretreatment, the levels of both cytokines were decreased to 182.6 ± 23.8 (MCP-1 and 5.46 ± 1.9 pg/mL for CCL-11. Blockade of MCP-1 or CCL-11 also shows similar result representing TJ protection from hypoxic stress. Conclusions. LBI results in a protective action from hypoxia.

Ketamine alleviates bradykinin-induced disruption of the mouse cerebrovascular endothelial cell-constructed tight junction barrier via a calcium-mediated redistribution of occludin polymerization

International Nuclear Information System (INIS)

Chen, Jui-Tai; Lin, Yi-Ling; Chen, Ta-Liang; Tai, Yu-Ting; Chen, Cheng-Yu; Chen, Ruei-Ming

2016-01-01

Highlights: • Ketamine could suppress bradykinin-induced intracellular calcium mobilization. • Ketamine induced B1R protein and mRNA expressions but did not change B2R protein levels. • Ketamine attenuated bradykinin-induced redistribution of occludin tight junctions. • Ketamine prevented bradykinin-induced breakage of the MCEC-constructed tight junction barrier. - Abstract: Following brain injury, a sequence of mechanisms leads to disruption of the blood-brain barrier (BBB) and subsequent cerebral edema, which is thought to begin with activation of bradykinin. Our previous studies showed that ketamine, a widely used intravenous anesthetic agent, can suppress bradykinin-induced cell dysfunction. This study further aimed to evaluate the protective effects of ketamine against bradykinin-induced disruption of the mouse cerebrovascular endothelial cell (MCEC)-constructed tight junction barrier and the possible mechanisms. Exposure of MCECs to bradykinin increased intracellular calcium (Ca 2+ ) concentrations in a time-dependent manner. However, pretreatment of MCECs with ketamine time- and concentration-dependently lowered the bradykinin-induced calcium influx. As to the mechanisms, although exposure of MCECs to ketamine induced bradykinin R1 receptor protein and mRNA expression, this anesthetic did not change levels of the bradykinin R2 receptor, a major receptor that responds to bradykinin stimulation. Bradykinin increased amounts of soluble occludin in MCECs, but pretreatment with ketamine alleviated this disturbance in occludin polymerization. Consequently, exposure to bradykinin decreased the transendothelial electronic resistance in the MCEC-constructed tight junction barrier. However, pretreatment with ketamine attenuated the bradykinin-induced disruption of the tight junction barrier. Taken together, this study shows that ketamine at a therapeutic concentration can protect against bradykinin-induced breakage of the BBB via suppressing calcium

Graphene-based electrochemical energy conversion and storage: fuel cells, supercapacitors and lithium ion batteries.

Science.gov (United States)

Hou, Junbo; Shao, Yuyan; Ellis, Michael W; Moore, Robert B; Yi, Baolian

2011-09-14

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. This journal is © the Owner Societies 2011

Electrochemical Testing of Gas Tungsten Arc Welded and Reduced Pressure Electron Beam Welded Alloy 22

International Nuclear Information System (INIS)

Day, S D; Wong, F G; Gordon, S R; Wong, L L; Rebak, R B

2006-01-01

Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the waste package program has been the integrity of the container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIG method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. It was of interest to compare the corrosion properties of specimens prepared using both types of welding techniques. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal (non-welded) to determine their relative corrosion behavior in simulated concentrated water (SCW) at 90 C (alkaline), 1 M HCl at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the same electrochemical behavior in the three tested electrolytes

Electrochemical Testing of Gas Tungsten ARC Welded and Reduced Pressure Electron Beam Welded Alloy 22

International Nuclear Information System (INIS)

S. Daniel Day; Frank M.G. Wong; Steven R. Gordon; Lana L. Wong; Raul B. Rebak

2006-01-01

Alloy 22 (N06022) is the material selected for the fabrication of the outer shell of the nuclear waste containers for the Yucca Mountain high-level nuclear waste repository site. A key technical issue in the waste package program has been the integrity of the container weld joints. The currently selected welding process for fabricating and sealing the containers is the traditional gas tungsten arc welding (GTAW) or TIC method. An appealing faster alternative technique is reduced pressure electron beam (RPEB) welding. It was of interest to compare the corrosion properties of specimens prepared using both types of welding techniques. Standard electrochemical tests were carried on GTAW and RPEB welds as well as on base metal (non-welded) to determine their relative corrosion behavior in simulated concentrated water (SCW) at 90 C (alkaline), 1 M HCI at 60 C (acidic) and 1 M NaCl at 90 C (neutral) solutions. Results show that for all practical purposes, the three tested materials had the same electrochemical behavior in the three tested electrolytes

Method of detecting defects in ion exchange membranes of electrochemical cells by chemochromic sensors

Science.gov (United States)

Brooker, Robert Paul; Mohajeri, Nahid

2016-01-05

A method of detecting defects in membranes such as ion exchange membranes of electrochemical cells. The electrochemical cell includes an assembly having an anode side and a cathode side with the ion exchange membrane in between. In a configuration step a chemochromic sensor is placed above the cathode and flow isolation hardware lateral to the ion exchange membrane which prevents a flow of hydrogen (H.sub.2) between the cathode and anode side. The anode side is exposed to a first reactant fluid including hydrogen. The chemochromic sensor is examined after the exposing for a color change. A color change evidences the ion exchange membrane has at least one defect that permits H.sub.2 transmission therethrough.

Electrochemical approach for monitoring the effect of anti tubulin drugs on breast cancer cells based on silicon nanograss electrodes.

Science.gov (United States)

Zanganeh, Somayeh; Khosravi, Safoora; Namdar, Naser; Amiri, Morteza Hassanpour; Gharooni, Milad; Abdolahad, Mohammad

2016-09-28

One of the most interested molecular research in the field of cancer detection is the mechanism of drug effect on cancer cells. Translating molecular evidence into electrochemical profiles would open new opportunities in cancer research. In this manner, applying nanostructures with anomalous physical and chemical properties as well as biocompatibility would be a suitable choice for the cell based electrochemical sensing. Silicon based nanostructure are the most interested nanomaterials used in electrochemical biosensors because of their compatibility with electronic fabrication process and well engineering in size and electrical properties. Here we apply silicon nanograss (SiNG) probing electrodes produced by reactive ion etching (RIE) on silicon wafer to electrochemically diagnose the effect of anticancer drugs on breast tumor cells. Paclitaxel (PTX) and mebendazole (MBZ) drugs have been used as polymerizing and depolymerizing agents of microtubules. PTX would perturb the anodic/cathodic responses of the cell-covered biosensor by binding phosphate groups to deformed proteins due to extracellular signal-regulated kinase (ERK(1/2)) pathway. MBZ induces accumulation of Cytochrome C in cytoplasm. Reduction of the mentioned agents in cytosol would change the ionic state of the cells monitored by silicon nanograss working electrodes (SiNGWEs). By extending the contacts with cancer cells, SiNGWEs can detect minor signal transduction and bio recognition events, resulting in precise biosensing. Effects of MBZ and PTX drugs, (with the concentrations of 2 nM and 0.1 nM, respectively) on electrochemical activity of MCF-7 cells are successfully recorded which are corroborated by confocal and flow cytometry assays. Copyright © 2016 Elsevier B.V. All rights reserved.

Electrochemical treatment of mixed and hazardous waste

International Nuclear Information System (INIS)

Dziewinski, J.; Marczak, S.; Smith, W.; Nuttall, E.

1995-01-01

Los Alamos National Laboratory (LANL) and The University of New Mexico are jointly developing an electrochemical process for treating hazardous and radioactive wastes. The wastes treatable by the process include toxic metal solutions, cyanide solutions, and various organic wastes that may contain chlorinated organic compounds. The main component of the process is a stack of electrolytic cells with peripheral equipment such as a rectifier, feed system, tanks with feed and treated solutions, and a gas-venting system. During the treatment, toxic metals are deposited on the cathode, cyanides are oxidized on the anode, and organic compounds are anodically oxidized by direct or mediated electrooxidation, depending on their type. Bench scale experimental studies have confirmed the feasibility of applying electrochemical systems to processing of a great variety of hazardous and mixed wastes. The operating parameters have been defined for different waste compositions using surrogate wastes. Mixed wastes are currently treated at bench scale as part of the treatability study

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

Science.gov (United States)

Pal, Uday B.; Isenberg, Arnold O.; Folser, George R.

1992-01-01

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

Tight closure and vanishing theorems

International Nuclear Information System (INIS)

Smith, K.E.

2001-01-01

Tight closure has become a thriving branch of commutative algebra since it was first introduced by Mel Hochster and Craig Huneke in 1986. Over the past few years, it has become increasingly clear that tight closure has deep connections with complex algebraic geometry as well, especially with those areas of algebraic geometry where vanishing theorems play a starring role. The purpose of these lectures is to introduce tight closure and to explain some of these connections with algebraic geometry. Tight closure is basically a technique for harnessing the power of the Frobenius map. The use of the Frobenius map to prove theorems about complex algebraic varieties is a familiar technique in algebraic geometry, so it should perhaps come as no surprise that tight closure is applicable to algebraic geometry. On the other hand, it seems that so far we are only seeing the tip of a large and very beautiful iceberg in terms of tight closure's interpretation and applications to algebraic geometry. Interestingly, although tight closure is a 'characteristic p' tool, many of the problems where tight closure has proved useful have also yielded to analytic (L2) techniques. Despite some striking parallels, there had been no specific result directly linking tight closure and L∼ techniques. Recently, however, the equivalence of an ideal central to the theory of tight closure was shown to be equivalent to a certain 'multiplier ideal' first defined using L2 methods. Presumably, deeper connections will continue to emerge. There are two main types of problems for which tight closure has been helpful: in identifying nice structure and in establishing uniform behavior. The original algebraic applications of tight closure include, for example, a quick proof of the Hochster-Roberts theorem on the Cohen-Macaulayness of rings of invariants, and also a refined version of the Brianqon-Skoda theorem on the uniform behaviour of integral closures of powers of ideals. More recent, geometric

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

Science.gov (United States)

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

2012-11-06

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 μL/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.

A Paper-Based Electrochromic Array for Visualized Electrochemical Sensing

OpenAIRE

Fengling Zhang; Tianyi Cai; Liang Ma; Liyuan Zhan; Hong Liu

2017-01-01

We report a battery-powered, paper-based electrochromic array for visualized electrochemical sensing. The paper-based sensing system consists of six parallel electrochemical cells, which are powered by an aluminum-air battery. Each single electrochemical cell uses a Prussian Blue spot electrodeposited on an indium-doped tin oxide thin film as the electrochromic indicator. Each electrochemical cell is preloaded with increasing amounts of analyte. The sample activates the battery for the sensin...

Electrochemical cell and negative electrode therefor

Science.gov (United States)

Kaun, Thomas D.

1982-01-01

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

Corrosion characterisation of laser beam and tungsten inert gas weldment of nickel base alloys: Micro-cell technique

International Nuclear Information System (INIS)

Abraham, Geogy J.; Kain, V.; Dey, G.K.; Raja, V.S.

2015-01-01

Highlights: • Grain matrix showed better corrosion resistance than grain boundary. • Microcell studies showed distinct corrosion behaviour of individual regions of weldment. • TIG welding resulted in increased stable anodic current density on weld fusion zone. • LB welding resulted in high stable anodic current density for heat affected zone. - Abstract: The electrochemical studies using micro-cell technique gave new understanding of electrochemical behaviour of nickel base alloys in solution annealed and welded conditions. The welding simulated regions depicted varied micro structural features. In case of tungsten inert gas (TIG) weldments, the weld fusion zone (WFZ) showed least corrosion resistance among all other regions. For laser beam (LB) weldments it was the heat-affected zone (HAZ) that showed comparatively high stable anodic current density. The high heat input of TIG welding resulted in slower heat dissipation hence increased carbide precipitation and segregation in WFZ resulting in high stable anodic current density

Effects of ethanol and acetaldehyde on tight junction integrity: in vitro study in a three dimensional intestinal epithelial cell culture model.

Directory of Open Access Journals (Sweden)

Elhaseen Elamin

Full Text Available BACKGROUND: Intestinal barrier dysfunction and translocation of endotoxins are involved in the pathogenesis of alcoholic liver disease. Exposure to ethanol and its metabolite, acetaldehyde at relatively high concentrations have been shown to disrupt intestinal epithelial tight junctions in the conventional two dimensional cell culture models. The present study investigated quantitatively and qualitatively the effects of ethanol at concentrations detected in the blood after moderate ethanol consumption, of its metabolite acetaldehyde and of the combination of both compounds on intestinal barrier function in a three-dimensional cell culture model. METHODS AND FINDINGS: Caco-2 cells were grown in a basement membrane matrix (Matrigel™ to induce spheroid formation and were then exposed to the compounds at the basolateral side. Morphological differentiation of the spheroids was assessed by immunocytochemistry and transmission electron microscopy. The barrier function was assessed by the flux of FITC-labeled dextran from the basal side into the spheroids' luminal compartment using confocal microscopy. Caco-2 cells grown on Matrigel assembled into fully differentiated and polarized spheroids with a central lumen, closely resembling enterocytes in vivo and provide an excellent model to study epithelial barrier functionality. Exposure to ethanol (10-40 mM or acetaldehyde (25-200 µM for 3 h, dose-dependently and additively increased the paracellular permeability and induced redistribution of ZO-1 and occludin without affecting cell viability or tight junction-encoding gene expression. Furthermore, ethanol and acetaldehyde induced lysine residue and microtubules hyperacetylation. CONCLUSIONS: These results indicate that ethanol at concentrations found in the blood after moderate drinking and acetaldehyde, alone and in combination, can increase the intestinal epithelial permeability. The data also point to the involvement of protein hyperacetylation in

unconventional natural gas reservoirs

International Nuclear Information System (INIS)

Correa G, Tomas F; Osorio, Nelson; Restrepo R, Dora P

2009-01-01

This work is an exploration about different unconventional gas reservoirs worldwide: coal bed methane, tight gas, shale gas and gas hydrate? describing aspects such as definition, reserves, production methods, environmental issues and economics. The overview also mentioned preliminary studies about these sources in Colombia.

How unconventional gas prospers without tax incentives

International Nuclear Information System (INIS)

Kuuskraa, V.A.; Stevens, S.H.

1995-01-01

It was widely believed that the development of unconventional natural gas (coalbed methane, gas shales, and tight gas) would die once US Sec. 29 credits stopped. Quieter voices countered, and hoped, that technology advances would keep these large but difficult to produce gas resources alive and maybe even healthy. Sec. 29 tax credits for new unconventional gas development stopped at the end of 1992. Now, nearly three years later, who was right and what has happened? There is no doubt that Sec. 29 tax credits stimulated the development of coalbed methane, gas shales, and tight gas. What is less known is that the tax credits helped spawn and push into use an entire new set of exploration, completion, and production technologies founded on improved understanding of unconventional gas reservoirs. As set forth below, while the incentives inherent in Sec. 29 provided the spark, it has been the base of science and technology that has maintained the vitality of these gas sources. The paper discusses the current status; resource development; technology; unusual production, proven reserves, and well completions if coalbed methane, gas shales, and tight gas; and international aspects

Flow and Transport in Tight and Shale Formations: A Review

KAUST Repository

Salama, Amgad

2017-09-18

A review on the recent advances of the flow and transport phenomena in tight and shale formations is presented in this work. Exploration of oil and gas in resources that were once considered inaccessible opened the door to highlight interesting phenomena that require attention and understanding. The length scales associated with transport phenomena in tight and shale formations are rich. From nanoscale phenomena to field-scale applications, a unified frame that is able to encounter the varieties of phenomena associated with each scale may not be possible. Each scale has its own tools and limitations that may not, probably, be suitable at other scales. Multiscale algorithms that effectively couple simulations among various scales of porous media are therefore important. In this article, a review of the different length scales and the tools associated with each scale is introduced. Highlights on the different phenomena pertinent to each scale are summarized. Furthermore, the governing equations describing flow and transport phenomena at different scales are investigated. In addition, methods to solve these equations using numerical techniques are introduced. Cross-scale analysis and derivation of linear and nonlinear Darcy\\'s scale laws from pore-scale governing equations are described. Phenomena occurring at molecular scales and their thermodynamics are discussed. Flow slippage at the nanosize pores and its upscaling to Darcy\\'s scale are highlighted. Pore network models are discussed as a viable tool to estimate macroscopic parameters that are otherwise difficult to measure. Then, the environmental aspects associated with the different technologies used in stimulating the gas stored in tight and shale formations are briefly discussed.

Flow and Transport in Tight and Shale Formations: A Review

KAUST Repository

Salama, Amgad; El-Amin, Mohamed; Kumar, Kundan; Sun, Shuyu

2017-01-01

A review on the recent advances of the flow and transport phenomena in tight and shale formations is presented in this work. Exploration of oil and gas in resources that were once considered inaccessible opened the door to highlight interesting phenomena that require attention and understanding. The length scales associated with transport phenomena in tight and shale formations are rich. From nanoscale phenomena to field-scale applications, a unified frame that is able to encounter the varieties of phenomena associated with each scale may not be possible. Each scale has its own tools and limitations that may not, probably, be suitable at other scales. Multiscale algorithms that effectively couple simulations among various scales of porous media are therefore important. In this article, a review of the different length scales and the tools associated with each scale is introduced. Highlights on the different phenomena pertinent to each scale are summarized. Furthermore, the governing equations describing flow and transport phenomena at different scales are investigated. In addition, methods to solve these equations using numerical techniques are introduced. Cross-scale analysis and derivation of linear and nonlinear Darcy's scale laws from pore-scale governing equations are described. Phenomena occurring at molecular scales and their thermodynamics are discussed. Flow slippage at the nanosize pores and its upscaling to Darcy's scale are highlighted. Pore network models are discussed as a viable tool to estimate macroscopic parameters that are otherwise difficult to measure. Then, the environmental aspects associated with the different technologies used in stimulating the gas stored in tight and shale formations are briefly discussed.

Proceedings of the natural gas research and development contractors review meeting

Energy Technology Data Exchange (ETDEWEB)

Malone, R.D.; Shoemaker, H.D.; Byrer, C.W. (eds.)

1990-11-01

The purpose of this meeting was to present results of the research in the DOE-sponsored Natural Gas Program, and simultaneously to provide a forum for real-time technology transfer, to the active research community, to the interested public, and to the natural gas industry, who are the primary users of this technology. The current research focus is to expand the base of near-term and mid-term economic gas resources through research activities in Eastern Tight Gas, Western Tight Gas, Secondary Gas Recovery (increased recovery of gas from mature fields); to enhance utilization, particularly of remote gas resources through research in Natural Gas to Liquids Conversion; and to develop additional, long term, potential gas resources through research in Gas Hydrates and Deep Gas. With the increased national emphasis on the use of natural gas, this forum has been expanded to include summaries of DOE-sponsored research in energy-related programs and perspectives on the importance of gas to future world energy. Thirty-two papers and fourteen poster presentations were given in seven formal, and one informal, sessions: Three general sessions (4 papers); Western Tight Gas (6 papers); Eastern Tight Gas (8 papers); Conventional/Speculative Resources (8 papers); and Gas to Liquids (6 papers). Individual reports are processed separately on the data bases.

Organic electrochemical transistors for cell-based impedance sensing

International Nuclear Information System (INIS)

Rivnay, Jonathan; Ramuz, Marc; Hama, Adel; Huerta, Miriam; Owens, Roisin M.; Leleux, Pierre

2015-01-01

Electrical impedance sensing of biological systems, especially cultured epithelial cell layers, is now a common technique to monitor cell motion, morphology, and cell layer/tissue integrity for high throughput toxicology screening. Existing methods to measure electrical impedance most often rely on a two electrode configuration, where low frequency signals are challenging to obtain for small devices and for tissues with high resistance, due to low current. Organic electrochemical transistors (OECTs) are conducting polymer-based devices, which have been shown to efficiently transduce and amplify low-level ionic fluxes in biological systems into electronic output signals. In this work, we combine OECT-based drain current measurements with simultaneous measurement of more traditional impedance sensing using the gate current to produce complex impedance traces, which show low error at both low and high frequencies. We apply this technique in vitro to a model epithelial tissue layer and show that the data can be fit to an equivalent circuit model yielding trans-epithelial resistance and cell layer capacitance values in agreement with literature. Importantly, the combined measurement allows for low biases across the cell layer, while still maintaining good broadband signal

House Dust Mite Der p 1 Effects on Sinonasal Epithelial Tight Junctions

Science.gov (United States)

Henriquez, Oswaldo A.; Beste, Kyle Den; Hoddeson, Elizabeth K.; Parkos, Charles A.; Nusrat, Asma; Wise, Sarah K.

2013-01-01

Background Epithelial permeability is highly dependent upon the integrity of tight junctions, cell-cell adhesion complexes located at the apical aspect of the lateral membrane of polarized epithelial cells. We hypothesize that sinonasal epithelial exposure to Der p 1 house dust mite antigen decreases expression of tight junction proteins (TJPs), representing a potential mechanism for increased permeability and presentation of antigens across the sinonasal epithelial layer. Methods Confluent cultured primary human sinonasal epithelial cells were exposed to recombinant Der p 1 antigen versus control, and transepithelial resistance measurements were performed over 24 hours. Antibody staining for a panel of tight junction proteins was examined with immunofluorescence/confocal microscopy and Western blotting. Tissue for these experiments was obtained from 4 patients total. Results Der p 1 exposed sinonasal cells showed a marked decrease in transepithelial resistance when compared to control cells. In addition, results of Western immunoblot and immunofluorescent labeling demonstrated decreased expression of TJPs claudin-1 and junction adhesion molecule-A (JAM-A) in Der p 1 exposed cultured sinonasal cells versus controls. Conclusion Der p 1 antigen exposure decreases sinonasal epithelium TJP expression, most notably seen in JAM-A and claudin-1 in these preliminary experiments. This decreased TJP expression likely contributes to increased epithelial permeability and represents a potential mechanism for transepithelial antigen exposure in allergic rhinitis. PMID:23592402

Method and closing pores in a thermally sprayed doped lanthanum chromite interconnection layer

Science.gov (United States)

Singh, Prabhakar; Ruka, Roswell J.

1995-01-01

A dense, substantially gas-tight electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an air electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO.sub.3 particles doped with an element or elements selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by thermal spraying doped LaCrO.sub.3 particles, either by plasma arc spraying or flame spraying; (C) depositing a mixture of CaO and Cr.sub.2 O.sub.3 on the surface of the thermally sprayed layer; and (D) heating the doped LaCrO.sub.3 layer coated with CaO and Cr.sub.2 O.sub.3 surface deposit at from about 1000.degree. C. to 1200.degree. C. to substantially close the pores, at least at a surface, of the thermally sprayed doped LaCrO.sub.3 layer. The result is a dense, substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the nonselected portion of the air electrode. A fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell, for example for generation of electrical power.

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

Science.gov (United States)

Schulz, Tobias; Weinmüller, Christian; Nabavi, Majid; Poulikakos, Dimos

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 micro-DMFC, especially the distinction between double layer charging and Faradaic reactions was shown. The effect of fuel flow rate, temperature, and anode flow channel structure on the impedance of the electrode reactions and membrane/electrode double layer charging were investigated. Analysis of impedance data revealed that the performance of the test cell was largely limited by the presence of intermediate carbon monoxide in the anode reaction. Higher temperatures increase cell performance by enabling intermediate CO to be oxidized at much higher rates. The results also revealed that serpentine anode flow microchannels show a lower tendency to intermediate CO coverage and a more stable cell behavior than parallel microchannels.

Electrochemical Characterization of TiO 2 Blocking Layers for Dye-Sensitized Solar Cells

KAUST Repository

Kavan, Ladislav; Té treault, Nicolas; Moehl, Thomas; Grä tzel, Michael

2014-01-01

Thin compact layers of TiO2 are grown by thermal oxidation of Ti, by spray pyrolysis, by electrochemical deposition, and by atomic layer deposition. These layers are used in dye-sensitized solar cells to prevent recombination of electrons from

Investigation of chemical and electrochemical reactions mechanisms in a direct carbon fuel cell using olive wood charcoal as sustainable fuel

Science.gov (United States)

Elleuch, Amal; Halouani, Kamel; Li, Yongdan

2015-05-01

Direct carbon fuel cell (DCFC) is a high temperature fuel cell using solid carbon as fuel. The use of environmentally friendly carbon material constitutes a promising option for the DCFC future. In this context, this paper focuses on the use of biomass-derived charcoal renewable fuel. A practical investigation of Tunisian olive wood charcoal (OW-C) in planar DCFCs is conducted and good power density (105 mW cm-2) and higher current density (550 mA cm-2) are obtained at 700 °C. Analytical and predictive techniques are performed to explore the relationships between fuel properties and DCFC chemical and electrochemical mechanisms. High carbon content, carbon-oxygen groups and disordered structure, are the key parameters allowing the achieved good performance. Relatively complex chain reactions are predicted to explain the gas evolution within the anode. CO, H2 and CH4 participation in the anodic reaction is proved.

Conversion of Carbon Dioxide to Ethanol by Electrochemical Synthesis Method Using Brass as A Cathode

Directory of Open Access Journals (Sweden)

Septian Ramadan

2017-09-01

Full Text Available The effect of potential and gas flow rate were investigated to determine the optimum conditions of the electrochemical synthesis process to convert carbon dioxide to ethanol. The conversion process is carried out using a NaHCO3 electrolyte solution in an electrochemical reactor equipped with a cathode and anode. As cathode is used brass, while as anode is used carbon. The result of the electrochemical synthesis process was analyzed by gas chromatography to determine the content of the compounds produced qualitatively and quantitatively. The optimum electrochemical synthesis conditions to convert carbon dioxide to ethanol are potential and gas flow rate are 3 volts and 0.5 L/minutes with ethanol concentration yielded 1.32%.

Process for electrochemically gasifying coal using electromagnetism

Science.gov (United States)

Botts, Thomas E.; Powell, James R.

1987-01-01

A process for electrochemically gasifying coal by establishing a flowing stream of coal particulate slurry, electrolyte and electrode members through a transverse magnetic field that has sufficient strength to polarize the electrode members, thereby causing them to operate in combination with the electrolyte to electrochemically reduce the coal particulate in the slurry. Such electrochemical reduction of the coal produces hydrogen and carbon dioxide at opposite ends of the polarized electrode members. Gas collection means are operated in conjunction with the process to collect the evolved gases as they rise from the slurry and electrolyte solution.

Potential evaluation of CO2 storage and enhanced oil recovery of tight oil reservoir in the Ordos Basin, China.

Science.gov (United States)

Tian, Xiaofeng; Cheng, Linsong; Cao, Renyi; Zhang, Miaoyi; Guo, Qiang; Wang, Yimin; Zhang, Jian; Cui, Yu

2015-07-01

Carbon -di-oxide (CO2) is regarded as the most important greenhouse gas to accelerate climate change and ocean acidification. The Chinese government is seeking methods to reduce anthropogenic CO2 gas emission. CO2 capture and geological storage is one of the main methods. In addition, injecting CO2 is also an effective method to replenish formation energy in developing tight oil reservoirs. However, exiting methods to estimate CO2 storage capacity are all based on the material balance theory. This was absolutely correct for normal reservoirs. However, as natural fractures widely exist in tight oil reservoirs and majority of them are vertical ones, tight oil reservoirs are not close. Therefore, material balance theory is not adaptive. In the present study, a new method to calculate CO2 storage capacity is presented. The CO2 effective storage capacity, in this new method, consisted of free CO2, CO2 dissolved in oil and CO2 dissolved in water. Case studies of tight oil reservoir from Ordos Basin was conducted and it was found that due to far lower viscosity of CO2 and larger solubility in oil, CO2 could flow in tight oil reservoirs more easily. As a result, injecting CO2 in tight oil reservoirs could obviously enhance sweep efficiency by 24.5% and oil recovery efficiency by 7.5%. CO2 effective storage capacity of Chang 7 tight oil reservoir in Longdong area was 1.88 x 10(7) t. The Chang 7 tight oil reservoir in Ordos Basin was estimated to be 6.38 x 10(11) t. As tight oil reservoirs were widely distributed in Songliao Basin, Sichuan Basin and so on, geological storage capacity of CO2 in China is potential.

Monitoring programmed cell death of living plant tissues in microfluidics using electrochemical and optical techniques

DEFF Research Database (Denmark)

Mark, Christina; Zor, Kinga; Heiskanen, Arto

such as redox activity, O2 and H2O2 concentration, pH, cell viability and release of target enzymes such as α-amylase. We have optimised an intracellular, whole-cell redox activity assay[3] that detects changes in redox activity in barley aleurone layer during PCD. The assay uses a double mediator......This project focuses on developing and applying a tissue culture system with electrochemical and optical detection techniques for tissue culture of barley aleurone layer to increase understanding of the underlying mechanisms of programmed cell death (PCD) in plants. The major advantage......-system to electrochemically measure redox activity via changes in the NADP:NADPH ratio. Experiments show that redox activity changes depend on phytohormone activation or inactivation of aleurone layer metabolism and subsequent PCD. We have also successfully detected PCD induced by phytohormones in barley aleurone layer using...

Electrochemical control of quantum interference in anthraquinone-based molecular switches

DEFF Research Database (Denmark)

Markussen, Troels; Schiøtz, Jakob; Thygesen, Kristian Sommer

2010-01-01

Using first-principles calculations we analyze the electronic transport properties of a recently proposed anthraquinone-based electrochemical switch. Robust conductance on/off ratios of several orders of magnitude are observed due to destructive quantum interference present in the anthraquinone...... of hopping via the localized orbitals. The topology of the tight-binding model, which is dictated by the symmetries of the molecular orbitals, determines the amount of quantum interference....

A Paper-Based Electrochromic Array for Visualized Electrochemical Sensing.

Science.gov (United States)

Zhang, Fengling; Cai, Tianyi; Ma, Liang; Zhan, Liyuan; Liu, Hong

2017-01-31

We report a battery-powered, paper-based electrochromic array for visualized electrochemical sensing. The paper-based sensing system consists of six parallel electrochemical cells, which are powered by an aluminum-air battery. Each single electrochemical cell uses a Prussian Blue spot electrodeposited on an indium-doped tin oxide thin film as the electrochromic indicator. Each electrochemical cell is preloaded with increasing amounts of analyte. The sample activates the battery for the sensing. Both the preloaded analyte and the analyte in the sample initiate the color change of Prussian Blue to Prussian White. With a reaction time of 60 s, the number of electrochemical cells with complete color changes is correlated to the concentration of analyte in the sample. As a proof-of-concept analyte, lactic acid was detected semi-quantitatively using the naked eye.

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

Science.gov (United States)

Cady, Susan G.

2014-01-01

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

Electrochemical reduction of oxygen on small platinum particles supported on carbon in concentrated phosphoric acid. 2. Effects of teflon content in the catalyst layer and baking temperature of the electrode

Energy Technology Data Exchange (ETDEWEB)

Maoka, T.

1988-03-01

A relation between hydrophobicity (or wettability) of a porous gas diffusion electrode for use in a phosphoric acid fuel cell and its cathode performance (activity toward electrochemical oxygen reduction) was examined. The hydrophobicity of the gas diffusion electrode was regulated by changing either the amount of Teflon (PTFE) content in the catalyst layer or baking temperature of the electrode. The Tafel slope or electrochemical oxygen reduction became twice as high as that of the ordinary electrode when the wettability of electrode toward phosphoric acid was high. This fact supports a flooded agglomerate model as the mode of this type of porous gas diffusion electrode.

Reduction reaction of chlorine gas in an Al-Cl2 chemical cell composed of molten chloride salts; Enkabutsu yoyuenkei Al-Cl2 kagaku denchi ni okeru enso gas no kangen hanno kyodo

Energy Technology Data Exchange (ETDEWEB)

Konda, S.; Sasaki, T.; Ishikawa, T. [Hokkaido University, Sapporo (Japan)

1996-10-05

The molten salt system electrochemical cycle was proposed to reproduce pure Al from scrap Al. The cycle is composed of production of rough AlCl3 by chlorination of scrap Al, refining of rough AlCl3 mainly by sublimation, and electrolytic reproduction of pure Al from refined AlCl3. In production of AlCl3, the Al-Cl2 molten salt system cell composed of anode dissolution reaction of Al and cathode reduction reaction of chlorine gas can generate electric power for the electrolytic reproduction. Chlorine gas can be recycled as anode product. Various experiments were carried out to improve molten salt system cells. In analysis of cell output, voltage drop from open circuit voltage was divided into that due to electrolytic bath resistance, and that due to reaction resistance. The electrolytic bath resistance could be determined from transient characteristics of voltage change just after cutoff of output current. The product of the obtained reaction resistance and a meniscus length was constant regardless of a meniscus length, and useful to predict scale-up cell performance. Output characteristics dependent on meniscus position were also obtained. 16 refs., 11 figs.

Electrochemically exfoliated graphene anodes with enhanced biocurrent production in single-chamber air-breathing microbial fuel cells.

Science.gov (United States)

Najafabadi, Amin Taheri; Ng, Norvin; Gyenge, Előd

2016-07-15

Microbial fuel cells (MFCs) present promising options for environmentally sustainable power generation especially in conjunction with waste water treatment. However, major challenges remain including low power density, difficult scale-up, and durability of the cell components. This study reports enhanced biocurrent production in a membrane-free MFC, using graphene microsheets (GNs) as anode and MnOx catalyzed air cathode. The GNs are produced by ionic liquid assisted simultaneous anodic and cathodic electrochemical exfoliation of iso-molded graphite electrodes. The GNs produced by anodic exfoliation increase the MFC peak power density by over 300% compared to plain carbon cloth (i.e., 2.85Wm(-2) vs 0.66Wm(-2), respectively), and by 90% compared to conventional carbon black (i.e., Vulcan XC-72) anode. These results exceed previously reported power densities for graphene-containing MFC anodes. The fuel cell polarization results are corroborated by electrochemical impedance spectroscopy indicating three times lower charge transfer resistance for the GN anode. Material characterizations suggest that the best performing GN samples were of relatively smaller size (~500nm), with higher levels of ionic liquid induced surface functionalization during the electrochemical exfoliation process. Copyright © 2016 Elsevier B.V. All rights reserved.

A gas circulation and purification system for gas-cell-based low-energy RI-beam production

Energy Technology Data Exchange (ETDEWEB)

Sonoda, T.; Wada, M.; Katayama, I.; Kojima, T. M.; Reponen, M. [RIKEN Nishina Center for Accelerator-Based Science, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Tsubota, T. [Tokyo KOATSU Co., Ltd., 1-9-8 Shibuya, Shibuyaku, Tokyo 150-0002 (Japan)

2016-06-15

A gas circulation and purification system was developed at the RIKEN Radioactive Isotope Beam Factory that can be used for gas-cell-based low-energy RI-beam production. A high-flow-rate gas cell filled with one atmosphere of buffer gas (argon or helium) is used for the deceleration and thermalization of high-energy RI-beams. The exhausted buffer gas is efficiently collected using a compact dry pump and returned to the gas cell with a recovery efficiency of >97%. The buffer gas is efficiently purified using two gas purifiers as well as collision cleaning, which eliminates impurities in the gas. An impurity level of one part per billion is achieved with this method.

Upper Paleozoic coal measures and unconventional natural gas systems of the Ordos Basin, China

Directory of Open Access Journals (Sweden)

Xuan Tang

2012-11-01

Full Text Available Upper Paleozoic coal measures in the Ordos Basin consist of dark mudstone and coal beds and are important source rocks for gas generation. Gas accumulations include coal-bed methane (CBM, tight gas and conventional gas in different structural areas. CBM accumulations are mainly distributed in the marginal area of the Ordos Basin, and are estimated at 3.5 × 1012 m3. Tight gas accumulations exist in the middle part of the Yishan Slope area, previously regarded as the basin-centered gas system and now considered as stratigraphic lithologic gas reservoirs. This paper reviews the characteristics of tight gas accumulations: poor physical properties (porosity < 8%, permeability < 0.85 × 10−3 μm2, abnormal pressure and the absence of well-defined gas water contacts. CBM is a self-generation and self-reservoir, while gas derived from coal measures migrates only for a short distance to accumulate in a tight reservoir and is termed near-generation and near-reservoir. Both CBM and tight gas systems require source rocks with a strong gas generation ability that extends together over wide area. However, the producing area of the two systems may be significantly different.

Ultrasensitive electrochemical aptasensor based on sandwich architecture for selective label-free detection of colorectal cancer (CT26) cells.

Science.gov (United States)

Hashkavayi, Ayemeh Bagheri; Raoof, Jahan Bakhsh; Ojani, Reza; Kavoosian, Saeid

2017-06-15

Colorectal cancer is one of the most common cancers in the world and has no effective treatment. Therefore, development of new methods for early diagnosis is instantly required. Biological recognition probes such as synthetic receptor and aptamer is one of the candidate recognition layers to detect important biomolecules. In this work, an electrochemical aptasensor was developed by fabricating an aptamer-cell-aptamer sandwich architecture on an SBA-15-3-aminopropyltriethoxysilane (SBA-15-pr-NH 2 ) and Au nanoparticles (AuNPs) modified graphite screen printed electrode (GSPE) surface for the selective, label-free detection of CT26 cancer cells. Based on the incubation of the thiolated aptamer with CT26 cells, the electron-transfer resistance of Fe (CN) 6 3-/4- redox couple increased considerably on the aptasensor surface. The results obtained from cyclic voltammetry and electrochemical impedance spectroscopy studies showed that the fabricated aptasensor can specifically identify CT26 cells in the concentration ranges of 10-1.0×10 5 cells/mL and 1.0×10 5 -6.0×10 6 cells/mL, respectively, with a detection limit of 2cells/mL. Applying the thiol terminated aptamer (5TR1) as a recognition layer led to a sensor with high affinity for CT26 cancer cells, compared to control cancer cells of AGS cells, VERO Cells, PC3 cells and SKOV-3 cells. Therefore a simple, rapid, label free, inexpensive, excellent, sensitive and selective electrochemical aptasensor based on sandwich architecture was developed for detection of CT26 Cells. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of pore structure on the seepage characteristics of tight sandstone reservoirs: A case study of Upper Jurassic Penglaizhen Fm reservoirs in the western Sichuan Basin

Directory of Open Access Journals (Sweden)

Liqiang Sima

2017-01-01

Full Text Available Tight sandstone reservoirs are characterized by complex pore structures and strong heterogeneity, and their seepage characteristics are much different from those of conventional sandstone reservoirs. In this paper, the tight sandstone reservoirs of Upper Jurassic Penglaizhen Fm in western Sichuan Basin were analyzed in terms of their pore structures by using the data about physical property, mercury injection and nuclear magnetic resonance (NMR tests. Then, the seepage characteristics and the gas–water two-phase migration mechanisms and distribution of tight sandstone reservoirs with different types of pore structures in the process of hydrocarbon accumulation and development were simulated by combining the relative permeability experiment with the visual microscopic displacement model. It is shown that crotch-like viscous fingering occurs in the process of gas front advancing in reservoirs with different pore structures. The better the pore structure is, the lower the irreducible water saturation is; the higher the gas-phase relative permeability of irreducible water is, the more easily the gas reservoir can be developed. At the late stage of development, the residual gas is sealed in reservoirs in the forms of bypass, cutoff and dead end. In various reservoirs, the interference between gas and water is stronger, so gas and water tends to be produced simultaneously. The sealed gas may reduce the production rate of gas wells significantly, and the existence of water phase may reduce the gas permeability greatly; consequently, the water-bearing low-permeability tight sandstone gas reservoirs reveal serious water production, highly-difficult development and low-recovery percentage at the late stage, which have adverse impacts on the effective production and development of gas wells.

The development of an electrochemical technique for in situ calibrating of combustible gas detectors

Science.gov (United States)

Shumar, J. W.; Lantz, J. B.; Schubert, F. H.

1976-01-01

A program to determine the feasibility of performing in situ calibration of combustible gas detectors was successfully completed. Several possible techniques for performing the in situ calibration were proposed. The approach that showed the most promise involved the use of a miniature water vapor electrolysis cell for the generation of hydrogen within the flame arrestor of a combustible gas detector to be used for the purpose of calibrating the combustible gas detectors. A preliminary breadboard of the in situ calibration hardware was designed, fabricated and assembled. The breadboard equipment consisted of a commercially available combustible gas detector, modified to incorporate a water vapor electrolysis cell, and the instrumentation required for controlling the water vapor electrolysis and controlling and calibrating the combustible gas detector. The results showed that operation of the water vapor electrolysis at a given current density for a specific time period resulted in the attainment of a hydrogen concentration plateau within the flame arrestor of the combustible gas detector.

Electrochemical Synthesis of Ammonia in Solid Electrolyte Cells

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Ioannis eGaragounis

2014-01-01

Full Text Available Developed in the early 1900's, the Haber-Bosch synthesis is the dominant NH3 synthesis process. Parallel to catalyst optimization, current research efforts are also focused on the investigation of new methods for ammonia synthesis, including the electrochemical synthesis with the use of solid electrolyte cells. Since the first report on Solid State Ammonia Synthesis (SSAS, more than 30 solid electrolyte materials were tested and at least 15 catalysts were used as working electrodes. Thus far, the highest rate of ammonia formation reported is 1.13×10−8 mol s−1 cm−2, obtained at 80°C with a Nafion solid electrolyte and a mixed oxide, SmFe0.7Cu0.1Ni0.2O3, cathode. At high temperatures (>500oC the maximum rate was 9.5*10-9 mol s−1 cm−2 using Ce0.8Y0.2O2-δ -[Ca3(PO42 -K3PO4] as electrolyte and Ag-Pd as cathode. In this paper, the advantages and the disadvantages of SSAS vs the conventional process and the requirements that must be met in order to promote the electrochemical process into an industrial level, are discussed.

Electrochemical Synthesis of Ammonia in Solid Electrolyte Cells

International Nuclear Information System (INIS)

Garagounis, Ioannis; Kyriakou, Vasileios; Skodra, Aglaia; Vasileiou, Eirini; Stoukides, Michael

2014-01-01

Developed in the early 1900s, the “Haber–Bosch” synthesis is the dominant NH 3 synthesis process. Parallel to catalyst optimization, current research efforts are also focused on the investigation of new methods for ammonia synthesis, including the electrochemical synthesis with the use of solid electrolyte cells. Since the first report on Solid State Ammonia Synthesis (SSAS), more than 30 solid electrolyte materials were tested and at least 15 catalysts were used as working electrodes. Thus far, the highest rate of ammonia formation reported is 1.13 × 10 -8 mol s -1 cm -2 , obtained at 80°C with a Nafion solid electrolyte and a mixed oxide, SmFe 0.7 Cu 0.1 Ni 0.2 O 3 , cathode. At high temperatures (>500°C), the maximum rate was 9.5 × 10 −9 mol s -1 cm -2 using Ce 0.8 Y 0.2 O 2-δ –[Ca 3 (PO 4 ) 2 –K 3 PO 4 ] as electrolyte and Ag–Pd as cathode. In this paper, the advantages and the disadvantages of SSAS vs. the conventional process and the requirements that must be met in order to promote the electrochemical process into an industrial level are discussed.

A Paper-Based Electrochromic Array for Visualized Electrochemical Sensing

Directory of Open Access Journals (Sweden)

Fengling Zhang

2017-01-01

Full Text Available We report a battery-powered, paper-based electrochromic array for visualized electrochemical sensing. The paper-based sensing system consists of six parallel electrochemical cells, which are powered by an aluminum-air battery. Each single electrochemical cell uses a Prussian Blue spot electrodeposited on an indium-doped tin oxide thin film as the electrochromic indicator. Each electrochemical cell is preloaded with increasing amounts of analyte. The sample activates the battery for the sensing. Both the preloaded analyte and the analyte in the sample initiate the color change of Prussian Blue to Prussian White. With a reaction time of 60 s, the number of electrochemical cells with complete color changes is correlated to the concentration of analyte in the sample. As a proof-of-concept analyte, lactic acid was detected semi-quantitatively using the naked eye.

An electrochemical sensor for determining elemental iodine in gas media

Energy Technology Data Exchange (ETDEWEB)

Goffman, V.G.; Shaimerdinov, B.U.; Kotelkin, I.M. [Institute of New Chemical Problems, Moscow (Russian Federation)] [and others

1993-12-01

The possibility of using solid-electrolyte Ag, AgI/AgI/Au cells as sensors for determining the concentration of elemental iodine in gas media is investigated. It is established that the sensor parameters are independent of oxygen content and radiation dose at different relative humidities.

Materials for electrochemical device safety

Science.gov (United States)

Vissers, Daniel R.; Amine, Khalil; Thackeray, Michael M.; Kahaian, Arthur J.; Johnson, Christopher S.

2015-04-07

An electrochemical device includes a thermally-triggered intumescent material or a gas-triggered intumescent material. Such devices prevent or minimize short circuits in a device that could lead to thermal run-away. Such devices may include batteries or supercapacitors.

Gas replacement system for fuel cell. Nenryo denchi no gas chikan hoshiki

Energy Technology Data Exchange (ETDEWEB)

Sugiyama, T

1990-02-14

When stopping the operation of a fuel cell, the gas in the reaction gas system is purged using such an inert gas as nitrogen for inactivation. A gas source such as inert gas bomb must be prepared beforehand for the purpose. This invention relates to a method of production of inert gas from the air collected from atmosphere to use it as the purge gas. The air collected from the atmosphere is passed through an oxygen remover filled with oxidation catalyst to remove oxygen, and dehumidified by a dehumidifier filled with drying agent, the obtained inert drying gas with nitrogen as the main constituent being used as the purge gas. Copper system catalyst supported by silica is used as the oxidation catalyst, and silica gel as the drying agent. After the operation of the fuel cell is re-started, a part of the high temperature fuel gas extracted from the reaction gas system is introduced to the oxygen remover for the reduction of oxidation catalyst and for heat regeneration of dehumidifying agent by the contained hydrogen. 1 fig.

3D Retro-Deformation of the Rotliegend of the `Tight Gas' Area, NGB

Science.gov (United States)

Tanner, D. C.; Krawczyk, C.; Oncken, O.; Baunack, C.; Gaupp, R.; Littke, R.; Schubarth-Engelschall, J.; Schwarzer, D.; Solms, M.; Trappe, H.

2003-04-01

We have constructed a detailed three-dimensional, geometrical model of the Rotliegend `Tight-Gas' reservoir (10 × 20 km^2) of the North German Basin (NGB) from 3D seismic and borehole data. From this data we have compiled an incremental tectonic history of the area, and retro-deformed faults within the model in time and 3D space. The Top Rotliegend surface lies at depths between 4490 m and 4910 m. We recognise three fault generations in the Rotliegend strata: 1) A NW--SE striking strike-slip fault. 2) N--S striking, dip-slip faults. 3) NE--SW striking faults with late and minor displacements. Vertical throw on all the faults is less than 150 m, but the strike-slip fault is characterized by rapid changes in fault throw along strike, whereas the dip-slip faults are composed of one or more segments which have coalesced over time. We envisage that 1) and 2) faults developed coevally in a transtensive setting. We perform 3D geometrical retro-deformation (i.e. reconstruction of the faulted blocks to the undeformed state) using the inclined-shear method. In this method, the hanging-wall is displaced upon the fault surface along a distinct movement vector, which is determined by the previous tectonic model. Morphology (i.e. curvature) of the fault causes passive deformation of the hanging-wall, which is accommodated by shear along a 3D vector. We present detailed fault analysis, and maps of the quantities and directions of the strain within the Rotliegend strata due to fault movement.

Electrochemical characteristics of vanadium redox reactions on porous carbon electrodes for microfluidic fuel cell applications

International Nuclear Information System (INIS)

Lee, Jin Wook; Hong, Jun Ki; Kjeang, Erik

2012-01-01

Microfluidic vanadium redox fuel cells are membraneless and catalyst-free fuel cells comprising a microfluidic channel network with two porous carbon electrodes. The anolyte and catholyte for fuel cell operation are V(II) and V(V) in sulfuric acid based aqueous solution. In the present work, the electrochemical characteristics of the vanadium redox reactions are investigated on commonly used porous carbon paper electrodes and compared to a standard solid graphite electrode as baseline. Half-cell electrochemical impedance spectroscopy is applied to measure the overall ohmic resistance and resistivity of the electrodes. Kinetic parameters for both V(II) and V(V) discharging reactions are extracted from Tafel plots and compared for the different electrodes. Cyclic voltammetry techniques reveal that the redox reactions are irreversible and that the magnitudes of peak current density vary significantly for each electrode. The obtained kinetic parameters for the carbon paper are implemented into a numerical simulation and the results show a good agreement with measured polarization curves from operation of a microfluidic vanadium redox fuel cell employing the same material as flow-through porous electrodes. Recommendations for microfluidic fuel cell design and operation are provided based on the measured trends.

Electrochemical sensor for detection of carcinoma

International Nuclear Information System (INIS)

Thakur, Bhawana; Sawant, Shilpa N.; Jayakumar, S.

2012-01-01

Detection of carcinoma in early stage is very important for its effective treatment. Although considerable advancement has been made in its detection and treatment, there is a significant need for rapid, low-cost, sensitive, and selective biosensors for detection of cancer. In recent years, electrochemical detection techniques have received much attention due to their rapid response, high sensitivity, and inherent selectivity. They can provide an inexpensive platform for detection of analytes in clinical diagnostics. Conducting polymers are a versatile material for development of electrochemical biosensors. Due to the conducting nature of these polymers, they act as a transducer to convert the biological signal into electrical signal. These polymers also exhibit good biocompatibility, hence are ideal for immobilisation of biological recognition element during the development of the sensor film. Recently author have demonstrated a whole cell based electrochemical biosensor for detection of the pesticide Lindane at very low concentrations. In the present study, we have tried to develop polyaniline based electrochemical sensor for detection of carcinoma. Polyaniline was deposited on gold interdigitated electrodes by electropolymerization using potentiodynamic method. The polymer film was suitably modified to obtain the sensor film for recognition of the tumour cells. Response of the sensor to various tumour cells such as lung cancer cells, human fibrosarcoma cells, prostate cancer cells, breast cancer cells was studied and was compared to that of normal cells. The sensor electrode could detect tumour cells based on the nature of response obtained

Catalytic and electrochemical behaviour of solid oxide fuel cell operated with simulated-biogas mixtures

Science.gov (United States)

Dang-Long, T.; Quang-Tuyen, T.; Shiratori, Y.

2016-06-01

Being produced from organic matters of wastes (bio-wastes) through a fermentation process, biogas mainly composed of CH4 and CO2 and can be considered as a secondary energy carrier derived from solar energy. To generate electricity from biogas through the electrochemical process in fuel cells is a state-of-the-art technology possessing higher energy conversion efficiency without harmful emissions compared to combustion process in heat engines. Getting benefits from high operating temperature such as direct internal reforming ability and activation of electrochemical reactions to increase overall system efficiency, solid oxide fuel cell (SOFC) system operated with biogas becomes a promising candidate for distributed power generator for rural applications leading to reductions of environmental issues caused by greenhouse effects and bio-wastes. CO2 reforming of CH4 and electrochemical oxidation of the produced syngas (H2-CO mixture) are two main reaction processes within porous anode material of SOFC. Here catalytic and electrochemical behavior of Ni-ScSZ (scandia stabilized-zirconia) anode in the feed of CH4-CO2 mixtures as simulated-biogas at 800 °C were evaluated. The results showed that CO2 had strong influences on both reaction processes. The increase in CO2 partial pressure resulted in the decrease in anode overvoltage, although open-circuit voltage was dropped. Besides that, the simulation result based on a power-law model for equimolar CH4-CO2 mixture revealed that coking hazard could be suppressed along the fuel flow channel in both open-circuit and closed-circuit conditions.

Structures, Compositions, and Activities of Live Shewanella Biofilms Formed on Graphite Electrodes in Electrochemical Flow Cells.

Science.gov (United States)

Kitayama, Miho; Koga, Ryota; Kasai, Takuya; Kouzuma, Atsushi; Watanabe, Kazuya

2017-09-01

An electrochemical flow cell equipped with a graphite working electrode (WE) at the bottom was inoculated with Shewanella oneidensis MR-1 expressing an anaerobic fluorescent protein, and biofilm formation on the WE was observed over time during current generation at WE potentials of +0.4 and 0 V (versus standard hydrogen electrodes), under electrolyte-flow conditions. Electrochemical analyses suggested the presence of unique electron-transfer mechanisms in the +0.4-V biofilm. Microscopic analyses revealed that, in contrast to aerobic biofilms, current-generating biofilm (at +0.4 V) was thin and flat (∼10 μm in thickness), and cells were evenly and densely distributed in the biofilm. In contrast, cells were unevenly distributed in biofilm formed at 0 V. In situ fluorescence staining and biofilm recovery experiments showed that the amounts of extracellular polysaccharides (EPSs) in the +0.4-V biofilm were much smaller than those in the aerobic and 0-V biofilms, suggesting that Shewanella cells suppress the production of EPSs at +0.4 V under flow conditions. We suggest that Shewanella cells perceive electrode potentials and modulate the structure and composition of biofilms to efficiently transfer electrons to electrodes. IMPORTANCE A promising application of microbial fuel cells (MFCs) is to save energy in wastewater treatment. Since current is generated in these MFCs by biofilm microbes under horizontal flows of wastewater, it is important to understand the mechanisms for biofilm formation and current generation under water-flow conditions. Although massive work has been done to analyze the molecular mechanisms for current generation by model exoelectrogenic bacteria, such as Shewanella oneidensis , limited information is available regarding the formation of current-generating biofilms over time under water-flow conditions. The present study developed electrochemical flow cells and used them to examine the electrochemical and structural features of current

Quantitative Label-Free Cell Proliferation Tracking with a Versatile Electrochemical Impedance Detection Platform

DEFF Research Database (Denmark)

Caviglia, Claudia; Carminati, M; Heiskanen, Arto

2012-01-01

optimal detection strategies. Electrochemical Impedance Spectroscopy (EIS) has been used to monitor and compare adhesion of different cell lines. HeLa cells and 3T3 fibroblasts have been cultured for 12 hours on interdigitated electrode arrays integrated into a tailor-made cell culture platform. Both......Since the use of impedance measurements for label-free monitoring of cells has become widespread but still the choice of sensing configuration is not unique though crucial for a quantitative interpretation of data, we demonstrate the application of a novel custom multipotentiostat platform to study...... vertical and coplanar interdigitated sensing configuration approaches have been used and compared on the same cell populations....

DNA sensor cGAS-mediated immune recognition

Directory of Open Access Journals (Sweden)

Pengyan Xia

2016-09-01

Full Text Available Abstract The host takes use of pattern recognition receptors (PRRs to defend against pathogen invasion or cellular damage. Among microorganism-associated molecular patterns detected by host PRRs, nucleic acids derived from bacteria or viruses are tightly supervised, providing a fundamental mechanism of host defense. Pathogenic DNAs are supposed to be detected by DNA sensors that induce the activation of NFκB or TBK1-IRF3 pathway. DNA sensor cGAS is widely expressed in innate immune cells and is a key sensor of invading DNAs in several cell types. cGAS binds to DNA, followed by a conformational change that allows the synthesis of cyclic guanosine monophosphate–adenosine monophosphate (cGAMP from adenosine triphosphate and guanosine triphosphate. cGAMP is a strong activator of STING that can activate IRF3 and subsequent type I interferon production. Here we describe recent progresses in DNA sensors especially cGAS in the innate immune responses against pathogenic DNAs.

Polymer based biosensor for rapid electrochemical detection of virus infection of human cells

DEFF Research Database (Denmark)

Kiilerich-Pedersen, Katrine; Poulsen, Claus R.; Jain, Titoo

2011-01-01

The demand in the field of medical diagnostics for simple, cost efficient and disposable devices is growing. Here, we present a label free, all-polymer electrochemical biosensor for detection of acute viral disease. The dynamics of a viral infection in human cell culture was investigated in a mic...

Electrolytes including fluorinated solvents for use in electrochemical cells

Science.gov (United States)

Tikhonov, Konstantin; Yip, Ka Ki; Lin, Tzu-Yuan

2015-07-07

Provided are electrochemical cells and electrolytes used to build such cells. The electrolytes include ion-supplying salts and fluorinated solvents capable of maintaining single phase solutions with the salts at between about -30.degree. C. to about 80.degree. C. The fluorinated solvents, such as fluorinated carbonates, fluorinated esters, and fluorinated esters, are less flammable than their non-fluorinated counterparts and increase safety characteristics of cells containing these solvents. The amount of fluorinated solvents in electrolytes may be between about 30% and 80% by weight not accounting weight of the salts. Fluorinated salts, such as fluoroalkyl-substituted LiPF.sub.6, fluoroalkyl-substituted LiBF.sub.4 salts, linear and cyclic imide salts as well as methide salts including fluorinated alkyl groups, may be used due to their solubility in the fluorinated solvents. In some embodiments, the electrolyte may also include a flame retardant, such as a phosphazene or, more specifically, a cyclic phosphazene and/or one or more ionic liquids.

Fuel Cell Power Plant Initiative. Volume II: Preliminary Design of a Fixed-Base LFP/SOFC Power System

National Research Council Canada - National Science Library

Veyo, S

1997-01-01

.... Fuel cells are electrochemical devices that directly convert the chemical energy contained in fuels such as hydrogen, natural gas, or coal gas into electricity at high efficiency with no intermediate...

Experience in North America Tight Oil Reserves Development. Horizontal Wells and Multistage Hydraulic Fracturing

Directory of Open Access Journals (Sweden)

R.R. Ibatullin

2017-09-01

Full Text Available The accelerated development of horizontal drilling technology in combination with the multistage hydraulic fracturing of the reservoir has expanded the geological conditions for commercial oil production from tight reservoirs in North America. Geological and physical characteristics of tight reservoirs in North America are presented, as well as a comparison of the geological and physical properties of the reservoirs of the Western Canadian Sedimentary Basin and the Volga-Ural oil and gas province, in particular, in the territory of Tatarstan. The similarity of these basins is shown in terms of formation and deposition. New drilling technologies for horizontal wells (HW and multistage hydraulic fracturing are considered. The drilling in tight reservoirs is carried out exclusively on hydrocarbon-based muds The multi-stage fracturing technology with the use of sliding sleeves, and also slick water – a low-viscous carrier for proppant is the most effective solution for conditions similar to tight reservoirs in the Devonian formation of Tatarstan. Tax incentives which are actively used for the development of HW and multistage fracturing technologies in Canada are described. wells, multistage fracturing

Effect of Chum Salmon Egg Lectin on Tight Junctions in Caco-2 Cell Monolayers

Directory of Open Access Journals (Sweden)

Ryo Nemoto

2015-05-01

Full Text Available The effect of a chum salmon egg lectin (CSL3 on tight junction (TJ of Caco-2 cell monolayers was investigated. The lectin opened TJ as indicated by the decrease of the transepithelial electrical resistance (TER value and the increase of the permeation of lucifer yellow, which is transported via the TJ-mediated paracellular pathway. The effects of CSL3 were inhibited by the addition of 10 mM L-rhamnose or D-galactose which were specific sugars for CSL3. The lectin increased the intracellular Ca2+ of Caco-2 cell monolayers, that could be inhibited by the addition of L-rhamnose. The fluorescence immunostaining of β-actin in Caco-2 cell monolayers revealed that the cytoskeleton was changed by the CSL3 treatment, suggesting that CSL3 depolymerized β-actin to cause reversible TJ structural and functional disruption. Although Japanese jack bean lectin and wheat germ lectin showed similar effects in the decrease of the TER values and the increase of the intracellular Ca2+, they could not be inhibited by the same concentrations of simple sugars, such as D-glucose and N-acetyl-D-glucosamine.

Operating a fuel cell using landfill gas

Energy Technology Data Exchange (ETDEWEB)

Trippel, C.E.; Preston, J.L. Jr.; Trocciola, J.; Spiegel, R.

1996-12-31

An ONSI PC25{trademark}, 200 kW (nominal capacity) phosphoric acid fuel cell operating on landfill gas is installed at the Town of Groton Flanders Road landfill in Groton, Connecticut. This joint project by the Connecticut Light & Power Company (CL&P) which is an operating company of Northeast Utilities, the Town of Groton, International Fuel Cells (IFC), and the US EPA is intended to demonstrate the viability of installing, operating and maintaining a fuel cell operating on landfill gas at a landfill site. The goals of the project are to evaluate the fuel cell and gas pretreatment unit operation, test modifications to simplify the GPU design and demonstrate reliability of the entire system.

Effects of Human Parvovirus B19 and Bocavirus VP1 Unique Region on Tight Junction of Human Airway Epithelial A549 Cells

Science.gov (United States)

Chiu, Chun-Ching; Shi, Ya-Fang; Yang, Jiann-Jou; Hsiao, Yuan-Chao; Tzang, Bor-Show; Hsu, Tsai-Ching

2014-01-01

As is widely recognized, human parvovirus B19 (B19) and human bocavirus (HBoV) are important human pathogens. Obviously, both VP1 unique region (VP1u) of B19 and HBoV exhibit the secreted phospholipase A2 (sPLA2)-like enzymatic activity and are recognized to participate in the pathogenesis of lower respiratory tract illnesses. However, exactly how, both VP1u from B19 and HBoV affect tight junction has seldom been addressed. Therefore, this study investigates how B19-VP1u and HBoV-VP1u may affect the tight junction of the airway epithelial A549 cells by examining phospholipase A2 activity and transepithelial electrical resistance (TEER) as well as performing immunoblotting analyses. Experimental results indicate that TEER is more significantly decreased in A549 cells by treatment with TNF-α (10 ng), two dosages of B19-VP1u and BoV-VP1u (400 ng and 4000 ng) or bee venom PLA2 (10 ng) than that of the control. Accordingly, more significantly increased claudin-1 and decreased occludin are detected in A549 cells by treatment with TNF-α or both dosages of HBoV-VP1u than that of the control. Additionally, more significantly decreased Na+/K+ ATPase is observed in A549 cells by treatment with TNF-α, high dosage of B19-VP1u or both dosages of BoV-VP1u than that of the control. Above findings suggest that HBoV-VP1u rather than B19 VP1u likely plays more important roles in the disruption of tight junction in the airway tract. Meanwhile, this discrepancy appears not to be associated with the secreted phospholipase A2 (sPLA2)-like enzymatic activity. PMID:25268969

Graphene nanocomposites for electrochemical cell electrodes

Science.gov (United States)

Zhamu, Aruna; Jang, Bor Z.; Shi, Jinjun

2015-11-19

A composite composition for electrochemical cell electrode applications, the composition comprising multiple solid particles, wherein (a) a solid particle is composed of graphene platelets dispersed in or bonded by a first matrix or binder material, wherein the graphene platelets are not obtained from graphitization of the first binder or matrix material; (b) the graphene platelets have a length or width in the range of 10 nm to 10 .mu.m; (c) the multiple solid particles are bonded by a second binder material; and (d) the first or second binder material is selected from a polymer, polymeric carbon, amorphous carbon, metal, glass, ceramic, oxide, organic material, or a combination thereof. For a lithium ion battery anode application, the first binder or matrix material is preferably amorphous carbon or polymeric carbon. Such a composite composition provides a high anode capacity and good cycling response. For a supercapacitor electrode application, the solid particles preferably have meso-scale pores therein to accommodate electrolyte.

A cell for the controllable thermal treatment and electrochemical characterisation of single crystal alloy electrodes

DEFF Research Database (Denmark)

Bondarenko, Alexander S.; Stephens, Ifan E.L.; Chorkendorff, Ib

2012-01-01

be performed in this cell. These include preparation and basic voltammetric characterisation of Cu/Pt(111) near-surface and surface alloys where monolayer amounts of Cu are located in the 1st and 2nd layers, respectively. The cell can also be useful for “electrochemical atomic layer epitaxy” to assemble...... multilayers using repetitive underpotential deposition....

1D + 3D two-phase flow numerical model of a proton exchange membrane fuel cell

International Nuclear Information System (INIS)

Ferreira, Rui B.; Falcão, D.S.; Oliveira, V.B.; Pinto, A.M.F.R.

2017-01-01

Highlights: •A 1D + 3D model of a PEM fuel cell is described and experimentally validated. •VOF method tracks the two-phase flow and electrochemical reactions are considered. •Water dynamics inside a serpentine channel is analyzed for different voltages. •Water content in different regions of channel is quantified. •Important issues on coupling of the VOF model with electrochemical reactions are addressed. -- Abstract: In this work, a numerical model of a proton exchange membrane (PEM) fuel cell is presented. The volume of fluid (VOF) method is employed to simulate the air-water two-phase flow in the cathode gas channel, at the same time that the cell electrochemical performance is predicted. The model is validated against an experimental polarization curve and through the visualization of water distribution inside a transparent fuel cell. The water dynamics inside a serpentine gas channel is numerically analyzed under different operating voltages. Moreover, water content in different regions of the channel is quantified. Current density and water generation rate spatial distributions are also displayed and it is shown how they affect the process of water emergence into the gas channel. Important issues on the simulation of the PEM fuel cells two-phase flow are addressed, especially concerning the coupling of the VOF technique with electrochemical reactions. Both the model and the numerical results aim to contribute to a better understanding of the two-phase flow phenomenon that occurs in these devices.

Exploiting the Gastric Epithelial Barrier: Helicobacter pylori's Attack on Tight and Adherens Junctions.

Science.gov (United States)

Backert, Steffen; Schmidt, Thomas P; Harrer, Aileen; Wessler, Silja

2017-01-01

Highly organized intercellular tight and adherens junctions are crucial structural components for establishing and maintenance of epithelial barrier functions, which control the microbiota and protect against intruding pathogens in humans. Alterations in these complexes represent key events in the development and progression of multiple infectious diseases as well as various cancers. The gastric pathogen Helicobacter pylori exerts an amazing set of strategies to manipulate these epithelial cell-to-cell junctions, which are implicated in changing cell polarity, migration and invasive growth as well as pro-inflammatory and proliferative responses. This chapter focuses on the H. pylori pathogenicity factors VacA, CagA, HtrA and urease, and how they can induce host cell signaling involved in altering cell-to-cell permeability. We propose a stepwise model for how H. pylori targets components of tight and adherens junctions in order to disrupt the gastric epithelial cell layer, giving fresh insights into the pathogenesis of this important bacterium.

Development of a Photosynthetic Microbial Electrochemical Cell (PMEC Reactor Coupled with Dark Fermentation of Organic Wastes: Medium Term Perspectives

Directory of Open Access Journals (Sweden)

Samir Bensaid

2015-01-01

Full Text Available In this article the concept, the materials and the exploitation potential of a photosynthetic microbial electrochemical cell for the production of hydrogen driven by solar power are investigated. In a photosynthetic microbial electrochemical cell, which is based on photosynthetic microorganisms confined to an anode and heterotrophic bacteria confined to a cathode, water is split by bacteria hosted in the anode bioactive film. The generated electrons are conveyed through external “bio-appendages” developed by the bacteria to transparent nano-pillars made of indium tin oxide (ITO, Fluorine-doped tin oxide (FTO or other conducting materials, and then transferred to the cathode. On the other hand, the generated protons diffuse to the cathode via a polymer electrolyte membrane, where they are reduced by the electrons by heterotrophic bacteria growing attached to a similar pillared structure as that envisaged for the anode and supplemented with a specific low cost substrate (e.g., organic waste, anaerobic digestion outlet. The generated oxygen is released to the atmosphere or stored, while the produced pure hydrogen leaves the electrode through the porous layers. In addition, the integration of the photosynthetic microbial electrochemical cell system with dark fermentation as acidogenic step of anaerobic digester, which is able to produce additional H2, and the use of microbial fuel cell, feed with the residues of dark fermentation (mainly volatile fatty acids, to produce the necessary extra-bias for the photosynthetic microbial electrochemical cell is here analyzed to reveal the potential benefits to this novel integrated technology.

Electrochemical promotion of catalytic reactions with Pt/C (or Pt/Ru/C)//PBI catalysts

DEFF Research Database (Denmark)

Petrushina, Irina; Bjerrum, Niels; Bandur, Viktor

2007-01-01

The paper is an overview of the results of the investigation on electrochemical promotion of three catalytic reactions: methane oxidation with oxygen, NO reduction with hydrogen at 135 degrees C and Fischer-Tropsch synthesis (FTS) at 170 degrees C in the [CH4/O-2(or NO/H-2 or CO/H-2)/Ar//Pt(or Pt....../Ru)//PBI(H3PO4)/H-2, Ar] fuel cell. It has been shown that the partial methane oxidation to C2H2 and the C-2 selectivity were electrochemically promoted by the negative catalyst polarization. This was also the case in NO reduction with hydrogen for low NO and H-2 partial pressures. In both cases the catalytic...... reactions have been promoted by the electrochemically produced hydrogen. It has been found that the NO reduction with hydrogen on the Pt/PBI strongly depends on NO and hydrogen partial pressures in the working gas mixture. At higher NO and H-2 partial pressures the catalysis is promoted...

Double strand break repair: two mechanisms in competition but tightly linked to cell cycle

International Nuclear Information System (INIS)

Delacote, F.

2002-11-01

DNA double strand breaks (DSB) are highly toxic damage although they can be induced to create genetic diversity. Two distinct pathways can repair DSB: Homologous Recombination (HR) and Non Homologous End Joining (NHEJ). If un- or mis-repaired, this damage can lead to cancer. Thus, it is essential to investigate how these two pathways are regulated for DSB repair. NHEJ inhibition leads to HR DSB repair stimulation. However, this channeling to HR is tightly linked to cell cycle since NHEJ and HR are active in G1/early S and late S/G2, respectively. Our results suggest that G1-unrepaired DSB go through S phase to be repaired by HR in G2. Those results allow a better understanding of DSB repair mechanisms regulation. (author)

Electrochemical Synthesis of Ammonia in Solid Electrolyte Cells

Energy Technology Data Exchange (ETDEWEB)

Garagounis, Ioannis; Kyriakou, Vasileios [Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki (Greece); Chemical Processes and Energy Resources Institute, Center for Research and Technology Hellas, Thessaloniki (Greece); Skodra, Aglaia [Chemical Processes and Energy Resources Institute, Center for Research and Technology Hellas, Thessaloniki (Greece); Vasileiou, Eirini; Stoukides, Michael, E-mail: stoukidi@cperi.certh.gr [Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki (Greece); Chemical Processes and Energy Resources Institute, Center for Research and Technology Hellas, Thessaloniki (Greece)

2014-01-17

Developed in the early 1900s, the “Haber–Bosch” synthesis is the dominant NH{sub 3} synthesis process. Parallel to catalyst optimization, current research efforts are also focused on the investigation of new methods for ammonia synthesis, including the electrochemical synthesis with the use of solid electrolyte cells. Since the first report on Solid State Ammonia Synthesis (SSAS), more than 30 solid electrolyte materials were tested and at least 15 catalysts were used as working electrodes. Thus far, the highest rate of ammonia formation reported is 1.13 × 10{sup -8} mol s{sup -1} cm{sup -2}, obtained at 80°C with a Nafion solid electrolyte and a mixed oxide, SmFe{sub 0.7}Cu{sub 0.1}Ni{sub 0.2}O{sub 3}, cathode. At high temperatures (>500°C), the maximum rate was 9.5 × 10{sup −9} mol s{sup -1} cm{sup -2} using Ce{sub 0.8}Y{sub 0.2}O{sub 2-δ}–[Ca{sub 3}(PO{sub 4}){sub 2}–K{sub 3}PO{sub 4}] as electrolyte and Ag–Pd as cathode. In this paper, the advantages and the disadvantages of SSAS vs. the conventional process and the requirements that must be met in order to promote the electrochemical process into an industrial level are discussed.

Catalytic and electrochemical behaviour of solid oxide fuel cell operated with simulated-biogas mixtures

Energy Technology Data Exchange (ETDEWEB)

Dang-Long, T., E-mail: 3TE14098G@kyushu-u.ac.jp [Department of Hydrogen Energy Systems, Faculty of Engineering, Kyushu University Motooka 744, Nishiku, Fukuoka, 810-0395 (Japan); Quang-Tuyen, T., E-mail: tran.tuyen.quang.314@m.kyushu-u.ac.jp [International Research Center for Hydrogen Energy, Kyushu University Motooka 744, Nishiku, Fukuoka, 810-0395 (Japan); Shiratori, Y., E-mail: shiratori.yusuke.500@m.kyushu-u.ac.jp [Department of Hydrogen Energy Systems, Faculty of Engineering, Kyushu University Motooka 744, Nishiku, Fukuoka, 810-0395 (Japan); International Research Center for Hydrogen Energy, Kyushu University Motooka 744, Nishiku, Fukuoka, 810-0395 (Japan)

2016-06-03

Being produced from organic matters of wastes (bio-wastes) through a fermentation process, biogas mainly composed of CH{sub 4} and CO{sub 2} and can be considered as a secondary energy carrier derived from solar energy. To generate electricity from biogas through the electrochemical process in fuel cells is a state-of-the-art technology possessing higher energy conversion efficiency without harmful emissions compared to combustion process in heat engines. Getting benefits from high operating temperature such as direct internal reforming ability and activation of electrochemical reactions to increase overall system efficiency, solid oxide fuel cell (SOFC) system operated with biogas becomes a promising candidate for distributed power generator for rural applications leading to reductions of environmental issues caused by greenhouse effects and bio-wastes. CO{sub 2} reforming of CH{sub 4} and electrochemical oxidation of the produced syngas (H{sub 2}–CO mixture) are two main reaction processes within porous anode material of SOFC. Here catalytic and electrochemical behavior of Ni-ScSZ (scandia stabilized-zirconia) anode in the feed of CH{sub 4}–CO{sub 2} mixtures as simulated-biogas at 800 °C were evaluated. The results showed that CO{sub 2} had strong influences on both reaction processes. The increase in CO{sub 2} partial pressure resulted in the decrease in anode overvoltage, although open-circuit voltage was dropped. Besides that, the simulation result based on a power-law model for equimolar CH{sub 4}−CO{sub 2} mixture revealed that coking hazard could be suppressed along the fuel flow channel in both open-circuit and closed-circuit conditions.

The Strategic Electrochemical Research Center in Denmark

DEFF Research Database (Denmark)

Mogensen, Mogens Bjerg; Hansen, Karin Vels

2011-01-01

A 6-year strategic electrochemistry research center (SERC) in fundamental and applied aspects of electrochemical cells with a main emphasis on solid oxide cells was started in Denmark on January 1st, 2007 in cooperation with other Danish and Swedish Universities. Furthermore, 8 Danish companies...... are presented. ©2011 COPYRIGHT ECS - The Electrochemical Society...

Electrochemically Promoted Organic Isomerization Reactions at Polymer Electrolyte Fuel Cell Cathodes

Science.gov (United States)

2011-01-04

fuel cells ( PEMFCs ) incorporate an ionomer membrane (e.g., Nafion 117) for support of electro- catalytic layers and proton conduction between the...central to PEMFC electrocatalysis. For example, a spin coated Nafion layer on polycrystalline Pt enhances electrocatalysis.7,8 Little is known about...CO Poisoning Effect in PEMFCs Operational at Temperatures up to 200°C. Journal of the Electrochemical Society, 2003. 150(12): p. A1599-A1605. 21

Improved Conversion Rates in Drug Screening Applications sing Miniaturized Electrochemical Cells with Frit Channels

NARCIS (Netherlands)

Odijk, Mathieu; Olthuis, Wouter; van den Berg, Albert; Qiao, L.; Girault, H.

2012-01-01

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

Enhanced nitrogen removal in single-chamber microbial fuel cells with increased gas diffusion areas

KAUST Repository

Yan, Hengjing

2012-11-23

Single-chamber microbial fuel cells (MFCs) with nitrifiers pre-enriched at the air cathodes have previously been demonstrated as a passive strategy for integrating nitrogen removal into current-generating bioelectrochemical systems. To further define system design parameters for this strategy, we investigated in this study the effects of oxygen diffusion area and COD/N ratio in continuous-flow reactors. Doubling the gas diffusion area by adding an additional air cathode or a diffusion cloth significantly increased the ammonia and COD removal rates (by up to 115% and 39%), ammonia removal efficiency (by up to 134%), the cell voltage and cathode potentials, and the power densities (by a factor of approximately 2). When the COD/N ratio was lowered from 13 to 3, we found up to 244% higher ammonia removal rate but at least 19% lower ammonia removal efficiency. An increase of COD removal rate by up to 27% was also found when the COD/N ratio was lowered from 11 to 3. The Coulombic efficiency was not affected by the additional air cathode, but decreased by an average of 11% with the addition of a diffusion cloth. Ammonia removal by assimilation was also estimated to understand the ammonia removal mechanism in these systems. These results showed that the doubling of gas diffusion area enhanced N and COD removal rates without compromising electrochemical performance. © 2012 Wiley Periodicals, Inc.

Electrochemical characterization of nano-sized Pd-based catalysts as cathode materials in direct methanol fuel cells.

Science.gov (United States)

Choi, M; Han, C; Kim, I T; An, J C; Lee, J J; Lee, H K; Shim, J

2011-01-01

To improve the catalytic activity of palladium (Pd) as a cathode catalyst in direct methanol fuel cells (DMFCs), we prepared palladium-titanium oxide (Pd-TiO2) catalysts which the Pd and TiO2 nanoparticles were simultaneously impregnated on carbon. We selected Pd and TiO2 as catalytic materials because of their electrochemical stability in acid solution. The crystal structure and the loading amount of Pd and TiO2 on carbon were characterized by X-ray diffraction (XRD) and energy dispersive X-ray microanalysis (EDX). The electrochemical characterization of Pd-TiO2/C catalysts for the oxygen reduction reaction was carried out in half and single cell systems. The catalytic activities of the Pd-TiO2 catalysts were strongly influenced by the TiO2 content. In the single cell test, the Pd-TiO2 catalysts showed very comparable performance to the Pt catalyst.

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

Science.gov (United States)

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

2012-04-01

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.

Fabrication of electrolytic cell for online post-column electrochemical derivatization in ion chromatography

Energy Technology Data Exchange (ETDEWEB)

Wu Shuchao [Department of Chemistry, Xixi Campus, Zhejiang University, Hangzhou 310028, Zhejiang (China); Xu Wei [State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310028, Zhejiang (China); Yang Bingcheng [School of Pharmacy, East China University of Science and Technology, Shanghai 200237 (China); Ye Mingli [Thermofisher scientific (China), Shanghai 201203 (China); Zhang Peimin [Department of Chemistry, Xixi Campus, Zhejiang University, Hangzhou 310028, Zhejiang (China); Shentu Chao [College of Biology and Environmental Engineering, Zhejiang Shuren University, Hangzhou 310015 (China); Zhu Yan, E-mail: zhuyan@zju.edu.cn [Department of Chemistry, Xixi Campus, Zhejiang University, Hangzhou 310028, Zhejiang (China)

2012-07-20

Highlight: Black-Right-Pointing-Pointer An electrolytic cell including ruthenium modified titanium electrode was fabricated. Black-Right-Pointing-Pointer Ion chromatography/electrochemical derivatization/fluorescence detection was developed. Black-Right-Pointing-Pointer Strong oxidation capacity of this EC was obtained by using the Ru/Ti electrode with large surface area. - Abstract: An electrolytic cell (EC), composed of two ruthenium-plated titanium electrodes separated by cation-exchange membranes, was fabricated and evaluated for online postcolumn derivatization in ion chromatography (IC). Folic acid (FA) and methotrexate (MTX) were preliminarily used as prototype analytes to test the performance of EC. After separation by an anion exchange column, FA and MTX, which emit very weak fluorescence when excited, were electrochemically oxidized online in the anode chamber of the EC. The compounds with strong fluorescence, which are oxidation products, were detected by the fluorescence detector. The phosphate buffer solution (100 mM KH{sub 2}PO{sub 4}) served as an optimal eluent for anion exchange chromatographic separation and a suitable supporting electrolyte for electro-oxidation, leading to ideal compatibility between IC separation and the postcolumn electrochemical derivatization. For the presently proposed method, the linear ranges were from 0.01 mg L{sup -1} to 5 mg L{sup -1} for both FA and MTX. The detection limits of FA and MTX were 1.8 and 2.1 {mu}g L{sup -1}, and the relative standard deviations (RSD, n = 7) were 2.9% and 3.6%, respectively. The method was applied for the simultaneous determination of FA and MTX in the plasma of patients being treated for rheumatoid arthritis. The determination of MTX in the urine of the patients of diffuse large B cell lymphoma was also demonstrated.

Intrinsic periodic and aperiodic stochastic resonance in an electrochemical cell

Science.gov (United States)

Tiwari, Ishant; Phogat, Richa; Parmananda, P.; Ocampo-Espindola, J. L.; Rivera, M.

2016-08-01

In this paper we show the interaction of a composite of a periodic or aperiodic signal and intrinsic electrochemical noise with the nonlinear dynamics of an electrochemical cell configured to study the corrosion of iron in an acidic media. The anodic voltage setpoint (V0) in the cell is chosen such that the anodic current (I ) exhibits excitable fixed point behavior in the absence of noise. The subthreshold periodic (aperiodic) signal consists of a train of rectangular pulses with a fixed amplitude and width, separated by regular (irregular) time intervals. The irregular time intervals chosen are of deterministic and stochastic origins. The amplitude of the intrinsic internal noise, regulated by the concentration of chloride ions, is then monotonically increased, and the provoked dynamics are analyzed. The signal to noise ratio and the cross-correlation coefficient versus the chloride ions' concentration curves have a unimodal shape indicating the emergence of an intrinsic periodic or aperiodic stochastic resonance. The abscissa for the maxima of these unimodal curves correspond to the optimum value of intrinsic noise where maximum regularity of the invoked dynamics is observed. In the particular case of the intrinsic periodic stochastic resonance, the scanning electron microscope images for the electrode metal surfaces are shown for certain values of chloride ions' concentrations. These images, qualitatively, corroborate the emergence of order as a result of the interaction between the nonlinear dynamics and the composite signal.

Particulate matter air pollution disrupts endothelial cell barrier via calpain-mediated tight junction protein degradation

Directory of Open Access Journals (Sweden)

Wang Ting

2012-08-01

Full Text Available Abstract Background Exposure to particulate matter (PM is a significant risk factor for increased cardiopulmonary morbidity and mortality. The mechanism of PM-mediated pathophysiology remains unknown. However, PM is proinflammatory to the endothelium and increases vascular permeability in vitro and in vivo via ROS generation. Objectives We explored the role of tight junction proteins as targets for PM-induced loss of lung endothelial cell (EC barrier integrity and enhanced cardiopulmonary dysfunction. Methods Changes in human lung EC monolayer permeability were assessed by Transendothelial Electrical Resistance (TER in response to PM challenge (collected from Ft. McHenry Tunnel, Baltimore, MD, particle size >0.1 μm. Biochemical assessment of ROS generation and Ca2+ mobilization were also measured. Results PM exposure induced tight junction protein Zona occludens-1 (ZO-1 relocation from the cell periphery, which was accompanied by significant reductions in ZO-1 protein levels but not in adherens junction proteins (VE-cadherin and β-catenin. N-acetyl-cysteine (NAC, 5 mM reduced PM-induced ROS generation in ECs, which further prevented TER decreases and atteneuated ZO-1 degradation. PM also mediated intracellular calcium mobilization via the transient receptor potential cation channel M2 (TRPM2, in a ROS-dependent manner with subsequent activation of the Ca2+-dependent protease calpain. PM-activated calpain is responsible for ZO-1 degradation and EC barrier disruption. Overexpression of ZO-1 attenuated PM-induced endothelial barrier disruption and vascular hyperpermeability in vivo and in vitro. Conclusions These results demonstrate that PM induces marked increases in vascular permeability via ROS-mediated calcium leakage via activated TRPM2, and via ZO-1 degradation by activated calpain. These findings support a novel mechanism for PM-induced lung damage and adverse cardiovascular outcomes.

Technological evaluation of fuel cells using natural gas for distributed power generation; Avaliacao tecnologica da utilizacao de gas natural em celulas a combustivel para geracao distribuida de energia

Energy Technology Data Exchange (ETDEWEB)

Brandao, Mauricio O. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE). Programa de Engenharia Mecanica; Giannini, Marcio P.; Arouca, Mauricio C. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia (COPPE). Programa de Planejamento Energetico

2004-07-01

The search for sustainable and more rational means of power generation motivates the scientific crew to search for more efficient and cleaner systems. Oil dependence becomes from the kind of development that the humanity had and cannot be dismissed. The question is how to use this source in a more intelligent way. Fuel Cells are electrochemical devices that convert into electric energy the chemical energy from oxi-reduction reactions between a fuel and an oxidant. The current fuel used in a Fuel Cell is hydrogen and oxygen is the oxidant. The great advantage of this device is its efficiency, higher than the one achieved with internal combustion engines. Also Fuel Cells are not limited by Carnot's efficiency. This paper is about the implementation of a distributed generation system using Fuel Cells. Technical aspects are approached together with economical and environmental needs. The already existence of Gas pipelines and the grown production of Natural Gas presented by Brazil turns it into a good market for the implementation of this energy source. The evaluation of this paper shows that is technically possible to use NG in Fuel Cells, mostly in South and Southeast regions, applying the distributed generation of energy concept. The most interesting in a strategic manner is that Brazil already have an indication that it's capable of developing this technology, opening a new market tuning with world's new technological developments. Many research centers develop this technology, not only from the cell composition itself, but also manufacturing techniques. (author)

Electrochemical and AFM Characterization of G-Quadruplex Electrochemical Biosensors and Applications

Science.gov (United States)

2018-01-01

Guanine-rich DNA sequences are able to form G-quadruplexes, being involved in important biological processes and representing smart self-assembling nanomaterials that are increasingly used in DNA nanotechnology and biosensor technology. G-quadruplex electrochemical biosensors have received particular attention, since the electrochemical response is particularly sensitive to the DNA structural changes from single-stranded, double-stranded, or hairpin into a G-quadruplex configuration. Furthermore, the development of an increased number of G-quadruplex aptamers that combine the G-quadruplex stiffness and self-assembling versatility with the aptamer high specificity of binding to a variety of molecular targets allowed the construction of biosensors with increased selectivity and sensitivity. This review discusses the recent advances on the electrochemical characterization, design, and applications of G-quadruplex electrochemical biosensors in the evaluation of metal ions, G-quadruplex ligands, and other small organic molecules, proteins, and cells. The electrochemical and atomic force microscopy characterization of G-quadruplexes is presented. The incubation time and cations concentration dependence in controlling the G-quadruplex folding, stability, and nanostructures formation at carbon electrodes are discussed. Different G-quadruplex electrochemical biosensors design strategies, based on the DNA folding into a G-quadruplex, the use of G-quadruplex aptamers, or the use of hemin/G-quadruplex DNAzymes, are revisited. PMID:29666699

Modulation of Tight Junction Structure and Function by Kinases and Phosphatases Targeting Occludin

Directory of Open Access Journals (Sweden)

Max Johannes Dörfel

2012-01-01

Full Text Available Tight junctions (TJs typically represent the most apical contacts in epithelial and endothelial cell layers where they play an essential role in the separation of extracellular or luminal spaces from underlying tissues in the body. Depending on the protein composition, TJs define the barrier characteristics and in addition maintain cell polarity. Two major families of integral membrane proteins form the typical TJ strand network, the tight junction-associated MARVEL protein (TAMP family members occludin, tricellulin, and MarvelD3 as well as a specific set of claudins. Occludin was the first identified member of these tetraspanins and is now widely accepted as a regulator of TJ assembly and function. Therefore, occludin itself has to be tightly regulated. Phosphorylation of occludin appears to be of central importance in this context. Here we want to summarize current knowledge on the kinases and phosphatases directly modifying occludin, and their role in the regulation of TJ structure, function, and dynamics.

Gamma radiation grafting process for preparing separator membranes for electrochemical cells

International Nuclear Information System (INIS)

Agostino, V.F. D'; Lee, J.Y.

1982-01-01

An irradiation grafting process for preparing separator membranes for use in electrochemical cells, comprises contacting a polymeric base film with an aqueous solution of a hydrophilic monomer and a polymerization retardant; and irradiating said contacted film to form a graft membrane having low electrical resistivity and having monomer molecules uniformly grafted thereon. In the examples (meth) acrylic acid is grafted on to polyethylene, polypropylene and polytetrafluoroethylene in the presence of ferrous sulphate or cupric sulphate as polymerization retardants. (author)

Electrochemical attosyringe.

Science.gov (United States)

Laforge, François O; Carpino, James; Rotenberg, Susan A; Mirkin, Michael V

2007-07-17

The ability to manipulate ultrasmall volumes of liquids is essential in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography. In cell biology, it is often necessary to inject material of high molecular weight (e.g., DNA, proteins) into living cells because their membranes are impermeable to such molecules. All techniques currently used for microinjection are plagued by two common problems: the relatively large injector size and volume of injected fluid, and poor control of the amount of injected material. Here we demonstrate the possibility of electrochemical control of the fluid motion that allows one to sample and dispense attoliter-to-picoliter (10(-18) to 10(-12) liter) volumes of either aqueous or nonaqueous solutions. By changing the voltage applied across the liquid/liquid interface, one can produce a sufficient force to draw solution inside a nanopipette and then inject it into an immobilized biological cell. A high success rate was achieved in injections of fluorescent dyes into cultured human breast cells. The injection of femtoliter-range volumes can be monitored by video microscopy, and current/resistance-based approaches can be used to control injections from very small pipettes. Other potential applications of the electrochemical syringe include fluid dispensing in nanolithography and pumping in microfluidic systems.

Protecting intestinal epithelial integrity by galacto-oligosaccharides: Keeping it tight

NARCIS (Netherlands)

Akbari, P.

2016-01-01

The intestinal barrier serves as a first line of host defense against potentially harmful stressors from the environment ingested with food, and is primarily formed by epithelial cells connected by tight junctions. Oligosaccharides have been identified as components in milk, particularly in

Method and system for purification of gas/liquid streams for fuel cells or electrolysis cells

DEFF Research Database (Denmark)

2013-01-01

at least one scrubber in the gas/liquid stream at the inlet side of the first electrode of the fuel cell or electrolysis cell; and/or providing at least one scrubber in the gas/liquid stream at the inlet side of the second electrode of the fuel cell or electrolysis cell; and - purifying the gas....../liquid streams towards the first and second electrode; wherein the at least one scrubber in the gas/liquid stream at the inlet side of the first electrode and/or the at least one scrubber in the gas/liquid stream at the inlet side of the second electrode comprises a material suitable as an electrolyte material...... with the at least one scrubber, with the proviso that the fuel cell or electrolysis cell is not a solid oxide cell....

Menadione metabolism to thiodione in hepatoblastoma by scanning electrochemical microscopy

Science.gov (United States)

Mauzeroll, Janine; Bard, Allen J.; Owhadian, Omeed; Monks, Terrence J.

2004-01-01

The cytotoxicity of menadione on hepatocytes was studied by using the substrate generation/tip collection mode of scanning electrochemical microscopy by exposing the cells to menadione and detecting the menadione-S-glutathione conjugate (thiodione) that is formed during the cellular detoxication process and is exported from the cell by an ATP-dependent pump. This efflux was electrochemically detected and allowed scanning electrochemical microscopy monitoring and imaging of single cells and groups of highly confluent live cells. Based on a constant flux model, ≈6 × 106 molecules of thiodione per cell per second are exported from monolayer cultures of Hep G2 cells. PMID:15601769

Detailed Electrochemical Characterisation of Large SOFC Stacks

DEFF Research Database (Denmark)

Mosbæk, Rasmus Rode; Hjelm, Johan; Barfod, R.

2012-01-01

application of advanced methods for detailed electrochemical characterisation during operation. An operating stack is subject to steep compositional gradients in the gaseous reactant streams, and significant temperature gradients across each cell and across the stack, which makes it a complex system...... Fuel Cell A/S was characterised in detail using electrochemical impedance spectroscopy. An investigation of the optimal geometrical placement of the current probes and voltage probes was carried out in order to minimise measurement errors caused by stray impedances. Unwanted stray impedances...... are particularly problematic at high frequencies. Stray impedances may be caused by mutual inductance and stray capacitance in the geometrical set-up and do not describe the fuel cell. Three different stack geometries were investigated by electrochemical impedance spectroscopy. Impedance measurements were carried...

Strain-dependent augmentation of tight-junction barrier function in human primary epidermal keratinocytes by Lactobacillus and Bifidobacterium lysates.

Science.gov (United States)

Sultana, Reshma; McBain, Andrew J; O'Neill, Catherine A

2013-08-01

In this study, we investigated whether probiotic lysates can modify the tight-junction function of human primary keratinocytes. The keratinocytes were grown on cell culture inserts and treated with lysates from Bifidobacterium longum, Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus fermentum, or Lactobacillus rhamnosus GG. With the exception of L. fermentum (which decreased cell viability), all strains markedly enhanced tight-junction barrier function within 24 h, as assessed by measurements of transepithelial electrical resistance (TEER). However, B. longum and L. rhamnosus GG were the most efficacious, producing dose-dependent increases in resistance that were maintained for 4 days. These increases in TEER correlated with elevated expression of tight-junction protein components. Neutralization of Toll-like receptor 2 abolished both the increase in TEER and expression of tight-junction proteins induced by B. longum, but not L. rhamnosus GG. These data suggest that some bacterial strains increase tight-junction function via modulation of protein components but the different pathways involved may vary depending on the bacterial strain.

Gas separation membrane module assembly

Science.gov (United States)

Wynn, Nicholas P [Palo Alto, CA; Fulton, Donald A [Fairfield, CA

2009-03-31

A gas-separation membrane module assembly and a gas-separation process using the assembly. The assembly includes a set of tubes, each containing gas-separation membranes, arranged within a housing. The housing contains a tube sheet that divides the space within the housing into two gas-tight spaces. A permeate collection system within the housing gathers permeate gas from the tubes for discharge from the housing.

Numerical Investigation of Cross Flow Phenomena in a Tight-Lattice Rod Bundle Using Advanced Interface Tracking Method

Science.gov (United States)

Zhang, Weizhong; Yoshida, Hiroyuki; Ose, Yasuo; Ohnuki, Akira; Akimoto, Hajime; Hotta, Akitoshi; Fujimura, Ken

In relation to the design of an innovative FLexible-fuel-cycle Water Reactor (FLWR), investigation of thermal-hydraulic performance in tight-lattice rod bundles of the FLWR is being carried out at Japan Atomic Energy Agency (JAEA). The FLWR core adopts a tight triangular lattice arrangement with about 1 mm gap clearance between adjacent fuel rods. In view of importance of accurate prediction of cross flow between subchannels in the evaluation of the boiling transition (BT) in the FLWR core, this study presents a statistical evaluation of numerical simulation results obtained by a detailed two-phase flow simulation code, TPFIT, which employs an advanced interface tracking method. In order to clarify mechanisms of cross flow in such tight lattice rod bundles, the TPFIT is applied to simulate water-steam two-phase flow in two modeled subchannels. Attention is focused on instantaneous fluctuation characteristics of cross flow. With the calculation of correlation coefficients between differential pressure and gas/liquid mixing coefficients, time scales of cross flow are evaluated, and effects of mixing section length, flow pattern and gap spacing on correlation coefficients are investigated. Differences in mechanism between gas and liquid cross flows are pointed out.

Polarization characteristics of composite electrodes in electrochemical cells with solid electrolytes based on CeO2 and LaGaO3

International Nuclear Information System (INIS)

Yaroslavtsev, I. Yu.; Kuzin, B. L.; Bronin, D. I.; Bogdanovich, N. M.

2005-01-01

For two types of electrochemical cells with oxygen-conducting solid electrolytes based on lanthanum gallate (LSGM) and cerium oxide (SDC) studied are the temperature dependences of the polarization conductivity of air electrodes prepared from lanthanum strontium manganite (LSM) and composites LSM-LSGM, LSM-SDC, and LSM-SSZ (SSZ is zirconium dioxide-based electrolyte). Effect of praseodymium oxide, added into these electrodes as a modifier, on their electrochemical properties is examined. Electrochemical systems with an LSM/LSGM interface exhibit low electrochemical activity toward the oxygen reaction, because during the formation of electrodes, LSM interacts with LSGM to form a poorly conducting product [ru

Electrochemical construction

Science.gov (United States)

Einstein, Harry; Grimes, Patrick G.

1983-08-23

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.

Electrochemical Synthesis of Ammonia from Water and Nitrogen using a Pt/GDC/Pt Cell

International Nuclear Information System (INIS)

Kim, Jong Nam; Yoo, Chung-Yul; Joo, Jong Hoon; Yu, Ji Haeng; Sharma, Monika; Yoon, Hyung Chul; Jeoung, Hana; Song, Ki Chang

2014-01-01

Electrochemical ammonia synthesis from water and nitrogen using a Pt/GDC/Pt cell was experimentally investigated. Electrochemical analysis and ammonia synthesis in the moisture-saturated nitrogen environment were performed under the operating temperature range 400-600 .deg. C and the applied potential range OCV (Open Circuit Voltage)-1.2V. Even though the ammonia synthesis rate was augmented with the increase in the operating temperature (i.e.. increase in the applied current) under the constant potential, the faradaic efficiency was decreased because of the limitation of dissociative chemisorption of nitrogen on the Pt electrode. The maximum synthesis rate of ammonia was 3.67x10 -11 mols -1 cm -2 with 0.1% faradaic efficiency at 600 .deg. C

Development of electrochemical reporter assay using HeLa cells transfected with vector plasmids encoding various responsive elements

Energy Technology Data Exchange (ETDEWEB)

Shiku, Hitoshi, E-mail: shiku@bioinfo.che.tohoku.ac.jp [Graduate School of Environmental Studies, Tohoku University, 6-6-11-604 Aramaki-Aoba, Sendai 980-8579 (Japan); Takeda, Michiaki; Murata, Tatsuya [Graduate School of Environmental Studies, Tohoku University, 6-6-11-604 Aramaki-Aoba, Sendai 980-8579 (Japan); Akiba, Uichi; Hamada, Fumio [Graduate School of Engineering and Resource Science, Akita University, 1-1 Tegata gakuen-machi, Akita 010-8502 (Japan); Matsue, Tomokazu, E-mail: matsue@bioinfo.che.tohoku.ac.jp [Graduate School of Environmental Studies, Tohoku University, 6-6-11-604 Aramaki-Aoba, Sendai 980-8579 (Japan)

2009-04-27

Electrochemical assay using HeLa cell lines transfected with various plasmid vectors encoding SEAP (secreted alkaline phosphatase) as the reporter has been performed by using SECM (scanning electrochemical microscopy). The plasmid vector contains different responsive elements that include GRE (glucocorticoid response elements), CRE (cAMP responsive elements), or {kappa}B (binding site for NF{kappa}B (nuclear factor kappa B)) upstream of the SEAP sequence. The transfected HeLa cells were patterned on a culture dish in a 4 x 4 array of circles of diameter 300 {mu}m by using the PDMS (poly(dimethylsiloxane)) stencil technique. The cellular array was first exposed to 100 ng mL{sup -1} dexamethasone, 10 ng mL{sup -1} forskolin, or 100 ng mL{sup -1} TNF-{alpha} (tumor necrosis factor {alpha}) after which it was further cultured in an RPMI culture medium for 6 h. After incubation, the cellular array was soaked in a measuring solution containing 4.7 mM PAPP (p-aminophenylphosphate) at pH 9.5, following which electrochemical measurements were performed immediately within 40 min. The SECM method allows parallel evaluation of different cell lines transfected with pGRE-SEAP, pCRE-SEAP, and pNF{kappa}B-SEAP patterned on the same solid support for detection of the oxidation current of PAP (p-aminophenol) flux produced from only 300 HeLa cells in each stencil pattern. The results of the SECM method were highly sensitive as compared to those obtained from the conventional CL (chemiluminescence) protocol with at least 5 x 10{sup 4} cells per well.

Cdt1 revisited: complex and tight regulation during the cell cycle and consequences of deregulation in mammalian cells

Directory of Open Access Journals (Sweden)

Fujita Masatoshi

2006-10-01

Full Text Available Abstract In eukaryotic cells, replication of genomic DNA initiates from multiple replication origins distributed on multiple chromosomes. To ensure that each origin is activated precisely only once during each S phase, a system has evolved which features periodic assembly and disassembly of essential pre-replication complexes (pre-RCs at replication origins. The pre-RC assembly reaction involves the loading of a presumptive replicative helicase, the MCM2-7 complexes, onto chromatin by the origin recognition complex (ORC and two essential factors, CDC6 and Cdt1. The eukaryotic cell cycle is driven by the periodic activation and inactivation of cyclin-dependent kinases (Cdks and assembly of pre-RCs can only occur during the low Cdk activity period from late mitosis through G1 phase, with inappropriate re-assembly suppressed during S, G2, and M phases. It was originally suggested that inhibition of Cdt1 function after S phase in vertebrate cells is due to geminin binding and that Cdt1 hyperfunction resulting from Cdt1-geminin imbalance induces re-replication. However, recent progress has revealed that Cdt1 activity is more strictly regulated by two other mechanisms in addition to geminin: (1 functional and SCFSkp2-mediated proteolytic regulation through phosphorylation by Cdks; and (2 replication-coupled proteolysis mediated by the Cullin4-DDB1Cdt2 ubiquitin ligase and PCNA, an eukaryotic sliding clamp stimulating replicative DNA polymerases. The tight regulation implies that Cdt1 control is especially critical for the regulation of DNA replication in mammalian cells. Indeed, Cdt1 overexpression evokes chromosomal damage even without re-replication. Furthermore, deregulated Cdt1 induces chromosomal instability in normal human cells. Since Cdt1 is overexpressed in cancer cells, this could be a new molecular mechanism leading to carcinogenesis. In this review, recent insights into Cdt1 function and regulation in mammalian cells are discussed.

Air electrode material for high temperature electrochemical cells

Science.gov (United States)

Ruka, Roswell J.

1985-01-01

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

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

Science.gov (United States)

Reichner, Philip; Dollard, Walter J.

1991-01-01

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

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

Science.gov (United States)

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

2015-06-01

Recent research on cellular circadian rhythms suggests that the coupling of transcription-translation feedback loops and intracellular redox oscillations is essential for robust circadian timekeeping. For clarification of the molecular mechanism underlying the circadian rhythm, methods that allow for the dynamic and simultaneous detection of transcription/translation and redox oscillations in living cells are needed. Herein, we report that the cyanobacterial circadian redox rhythm can be electrochemically detected based on extracellular electron transfer (EET), a process in which intracellular electrons are exchanged with an extracellular electrode. As the EET-based method is non-destructive, concurrent detection with transcription/translation rhythm using bioluminescent reporter strains becomes possible. An EET pathway that electrochemically connected the intracellular region of cyanobacterial cells with an extracellular electrode was constructed via a newly synthesized electron mediator with cell membrane permeability. In the presence of the mediator, the open circuit potential of the culture medium exhibited temperature-compensated rhythm with approximately 24 h periodicity. Importantly, such circadian rhythm of the open circuit potential was not observed in the absence of the electron mediator, indicating that the EET process conveys the dynamic information regarding the intracellular redox state to the extracellular electrode. These findings represent the first direct demonstration of the intracellular circadian redox rhythm of cyanobacterial cells. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Stability of spinor Fermi gases in tight waveguides

International Nuclear Information System (INIS)

Campo, A. del; Muga, J. G.; Girardeau, M. D.

2007-01-01

The two- and three-body correlation functions of the ground state of an optically trapped ultracold spin-(1/2) Fermi gas (SFG) in a tight waveguide [one-dimensional (1D) regime] are calculated in the plane of even- and odd-wave coupling constants, assuming a 1D attractive zero-range odd-wave interaction induced by a 3D p-wave Feshbach resonance, as well as the usual repulsive zero-range even-wave interaction stemming from 3D s-wave scattering. The calculations are based on the exact mapping from the SFG to a 'Lieb-Liniger-Heisenberg' model with delta-function repulsions depending on isotropic Heisenberg spin-spin interactions, and indicate that the SFG should be stable against three-body recombination in a large region of the coupling constant plane encompassing parts of both the ferromagnetic and antiferromagnetic phases. However, the limiting case of the fermionic Tonks-Girardeau gas, a spin-aligned 1D Fermi gas with infinitely attractive p-wave interactions, is unstable in this sense. Effects due to the dipolar interaction and a Zeeman term due to a resonance-generating magnetic field do not lead to shrinkage of the region of stability of the SFG

Tight junction between endothelial cells: the interaction between nanoparticles and blood vessels

Directory of Open Access Journals (Sweden)

Yue Zhang

2016-05-01

Full Text Available Since nanoparticles are now widely applied as food additives, in cosmetics and other industries, especially in medical therapy and diagnosis, we ask here whether nanoparticles can cause several adverse effects to human health. In this review, based on research on nanotoxicity, we mainly discuss the negative influence of nanoparticles on blood vessels in several aspects and the potential mechanism for nanoparticles to penetrate endothelial layers of blood vessels, which are the sites of phosphorylation of tight junction proteins (claudins, occludins, and ZO (Zonula occludens proteins, oxidative stress and shear stress. We propose a connection between the presence of nanoparticles and the regulation of the tight junction, which might be the key approach for nanoparticles to penetrate endothelial layers and then have an impact on other tissues and organs.

Experimental and Numerical Study of the Effect of Gas-Shrouded Plasma Spraying on Cathode Coating of Alkaline Electrolysis Cells

Science.gov (United States)

Liu, T.; Reißner, R.; Schiller, G.; Ansar, A.

2018-01-01

The aim of this work is to improve the performance of electrodes prepared via atmospheric plasma spray by means of gas shrouding which is expected to apparently reduce the oxygen content of the plasma plume and subsequently improve the coating quality. Electrodes with dual-layer coating for alkaline water electrolysis were deposited on Ni-coated perforated substrates. Microstructure and morphology were studied by SEM. Element content was measured by EDS. Enthalpy probe was employed for measuring plasma temperature and velocity as well as the gas composition. For verifying and better understanding the shrouding effect numerical calculation was carried out according to the experimental settings. Electrochemical test was carried out to validate the shrouding effect. The results showed slight protecting effect of gas shrouding on plasma plume and the final coating. Over the dual-layer section, the measured oxygen fraction was 3.46 and 3.15% for the case without gas shrouding and with gas shrouding, respectively. With gas shrouding the coating exhibited similar element contents as the coating sprayed by VPS, while no obvious improvement was observed in the microstructure or the morphology. Evident electrochemical improvement was nevertheless achieved that with gas shrouding the electrode exhibited similar performance as that of the VPS-sprayed electrode.

Ionic Liquid-Based Optical and Electrochemical Carbon Dioxide Sensors

Science.gov (United States)

Behera, Kamalakanta; Pandey, Shubha; Kadyan, Anu; Pandey, Siddharth

2015-01-01

Due to their unusual physicochemical properties (e.g., high thermal stability, low volatility, high intrinsic conductivity, wide electrochemical windows and good solvating ability), ionic liquids have shown immense application potential in many research areas. Applications of ionic liquid in developing various sensors, especially for the sensing of biomolecules, such as nucleic acids, proteins and enzymes, gas sensing and sensing of various important ions, among other chemosensing platforms, are currently being explored by researchers worldwide. The use of ionic liquids for the detection of carbon dioxide (CO2) gas is currently a major topic of research due to the associated importance of this gas with daily human life. This review focuses on the application of ionic liquids in optical and electrochemical CO2 sensors. The design, mechanism, sensitivity and detection limit of each type of sensor are highlighted in this review. PMID:26690155

Ionic Liquid-Based Optical and Electrochemical Carbon Dioxide Sensors.

Science.gov (United States)

Behera, Kamalakanta; Pandey, Shubha; Kadyan, Anu; Pandey, Siddharth

2015-12-04

Due to their unusual physicochemical properties (e.g., high thermal stability, low volatility, high intrinsic conductivity, wide electrochemical windows and good solvating ability), ionic liquids have shown immense application potential in many research areas. Applications of ionic liquid in developing various sensors, especially for the sensing of biomolecules, such as nucleic acids, proteins and enzymes, gas sensing and sensing of various important ions, among other chemosensing platforms, are currently being explored by researchers worldwide. The use of ionic liquids for the detection of carbon dioxide (CO₂) gas is currently a major topic of research due to the associated importance of this gas with daily human life. This review focuses on the application of ionic liquids in optical and electrochemical CO₂ sensors. The design, mechanism, sensitivity and detection limit of each type of sensor are highlighted in this review.

Ionic Liquid-Based Optical and Electrochemical Carbon Dioxide Sensors

Directory of Open Access Journals (Sweden)

Kamalakanta Behera

2015-12-01

Full Text Available Due to their unusual physicochemical properties (e.g., high thermal stability, low volatility, high intrinsic conductivity, wide electrochemical windows and good solvating ability, ionic liquids have shown immense application potential in many research areas. Applications of ionic liquid in developing various sensors, especially for the sensing of biomolecules, such as nucleic acids, proteins and enzymes, gas sensing and sensing of various important ions, among other chemosensing platforms, are currently being explored by researchers worldwide. The use of ionic liquids for the detection of carbon dioxide (CO2 gas is currently a major topic of research due to the associated importance of this gas with daily human life. This review focuses on the application of ionic liquids in optical and electrochemical CO2 sensors. The design, mechanism, sensitivity and detection limit of each type of sensor are highlighted in this review.

Large-scale calculations of solid oxide fuel cell cermet anode by tight-binding quantum chemistry method

International Nuclear Information System (INIS)

Koyama, Michihisa; Kubo, Momoji; Miyamoto, Akira

2005-01-01

Improvement of anode characteristics of solid oxide fuel cells is important for the better cell performance and especially the direct use of hydrocarbons. A mixture of ceramics and metal is generally used as anode, and different combinations of ceramics and metals lead to different electrode characteristics. We performed large-scale calculations to investigate the characteristics of Ni/CeO 2 and Cu/CeO 2 anodes at the electronic level using our tight-binding quantum chemical molecular dynamics program. Charge distribution analysis clarified the electron transfer from metal to oxide in both anodes. The calculations of density of states clarified different contributions of Ni and Cu orbitals to the energy levels at around Fermi level in each cermet. Based on the obtained results, we made considerations to explain different characteristics of both cermet anodes. The effectiveness of our approach for the investigation of complex cermet system was proved

Gas cell neutralizers (Fundamental principles)

International Nuclear Information System (INIS)

Fuehrer, B.

1985-06-01

Neutralizing an ion-beam of the size and energy levels involved in the neutral-particle-beam program represents a considerable extension of the state-of-the-art of neutralizer technology. Many different mediums (e.g., solid, liquid, gas, plasma, photons) can be used to strip the hydrogen ion of its extra electron. A large, multidisciplinary R and D effort will no doubt be required to sort out all of the ''pros and cons'' of these various techniques. The purpose of this particular presentation is to discuss some basic configurations and fundamental principles of the gas type of neutralizer cell. Particular emphasis is placed on the ''Gasdynamic Free-Jet'' neutralizer since this configuration has the potential of being much shorter than other type of gas cells (in the beam direction) and it could operate in nearly a continuous mode (CW) if necessary. These were important considerations in the ATSU design which is discussed in some detail in the second presentation entitled ''ATSU Point Design''

Electrochemical synthesis of hydrogen peroxide: Rotating disk electrode and fuel cell studies

International Nuclear Information System (INIS)

Lobyntseva, Elena; Kallio, Tanja; Alexeyeva, Nadezda; Tammeveski, Kaido; Kontturi, Kyoesti

2007-01-01

The electrochemical reduction of oxygen on various catalysts was studied using the thin-layer rotating disk electrode (RDE) method. High-surface-area carbon was modified with an anthraquinone derivative and gold nanoparticles. Polytetrafluoroethylene (PTFE) and cationic polyelectrolyte (FAA) were used as binders in the preparation of thin-film electrodes. Our primary goal was to find a good electrocatalyst for the two-electron reduction of oxygen to hydrogen peroxide. All electrochemical measurements were carried out in 0.1 M KOH. Cyclic voltammetry was used in order to characterise the surface processes of the modified electrodes in O 2 -free electrolyte. The RDE results revealed that the carbon-supported gold nanoparticles are active catalysts for the four-electron reduction of oxygen in alkaline solution. Anthraquinone-modified high-area carbon catalyses the two-electron reduction at low overpotentials, which is advantageous for hydrogen peroxide production. In addition, the polymer electrolyte fuel cell technology was used for the generation of hydrogen peroxide. The cell was equipped with a bipolar membrane which consisted of commercial Nafion 117 as a cation-exchange layer and FT-FAA as an anion-exchange layer. The bipolar membranes were prepared by a hot pressing method. Use of the FAA ionomer as a binder for the anthraquinone-modified carbon catalyst resulted in production of hydrogen peroxide

Fuel cell R&D at the CSIR

CSIR Research Space (South Africa)

Hietkamp, S

2006-02-01

Full Text Available similarly to a battery, which uses electrochemical conversion, fuel cells take in hydrogen- rich fuel and oxygen and turn them into electricity and heat. The hydrogen used can be derived from gasoline, natural gas, propane or methanol. Within the CSIR...

Conversion of Wastes into Bioelectricity and Chemicals by Using Microbial Electrochemical Technologies

KAUST Repository

Logan, B. E.

2012-08-09

Waste biomass is a cheap and relatively abundant source of electrons for microbes capable of producing electrical current outside the cell. Rapidly developing microbial electrochemical technologies, such as microbial fuel cells, are part of a diverse platform of future sustainable energy and chemical production technologies. We review the key advances that will enable the use of exoelectrogenic microorganisms to generate biofuels, hydrogen gas, methane, and other valuable inorganic and organic chemicals. Moreover, we examine the key challenges for implementing these systems and compare them to similar renewable energy technologies. Although commercial development is already underway in several different applications, ranging from wastewater treatment to industrial chemical production, further research is needed regarding efficiency, scalability, system lifetimes, and reliability.

Conversion of wastes into bioelectricity and chemicals by using microbial electrochemical technologies.

Science.gov (United States)

Logan, Bruce E; Rabaey, Korneel

2012-08-10

Waste biomass is a cheap and relatively abundant source of electrons for microbes capable of producing electrical current outside the cell. Rapidly developing microbial electrochemical technologies, such as microbial fuel cells, are part of a diverse platform of future sustainable energy and chemical production technologies. We review the key advances that will enable the use of exoelectrogenic microorganisms to generate biofuels, hydrogen gas, methane, and other valuable inorganic and organic chemicals. Moreover, we examine the key challenges for implementing these systems and compare them to similar renewable energy technologies. Although commercial development is already underway in several different applications, ranging from wastewater treatment to industrial chemical production, further research is needed regarding efficiency, scalability, system lifetimes, and reliability.

Reflection-mode x-ray powder diffraction cell for in situ studies of electrochemical reactions

International Nuclear Information System (INIS)

Roberts, G.A.; Stewart, K.D.

2004-01-01

The design and operation of an electrochemical cell for reflection-mode powder x-ray diffraction experiments are discussed. The cell is designed for the study of electrodes that are used in rechargeable lithium batteries. It is designed for assembly in a glove box so that air-sensitive materials, such as lithium foil electrodes and carbonate-based electrolytes with lithium salts, can be used. The cell uses a beryllium window for x-ray transmission and electrical contact. A simple mechanism for compressing the electrodes is included in the design. Sample results for the cell are shown with a Cu Kα source and a position-sensitive detector

Electrochemical evaluation of electrocatalysts for fuel cell applications : a practical approach

Energy Technology Data Exchange (ETDEWEB)

Atwan, M.H. [General Motors R and D Technical Center, Warren, MI (United States); Gyenge, E.L. [British Columbia Univ., Vancouver, BC (Canada). Dept. of Chemical and Biological Engineering; Northwood, D.O. [Windsor Univ., ON (Canada). Dept. of Mechanical, Automotive and Materials Engineering

2010-07-01

Various electrochemical techniques were used to investigate supported nano-size electrocatalysts during the oxidation of a specific fuel for fuel cell applications. Cyclic voltammetry (CV) on static and dynamic rotating disc electrodes (RDE) and fuel cell station tests demonstrated that the most active catalyst showed the most negative oxidation peak potential. A Tafel equation indicated that a low anodic/cathodic overpotential was a clear indication of higher catalytic activity. The lower overpotential was achieved for a specific current load by ensuring a low Tafel slope and as high an exchange current density as possible. The RDE and fuel cell station tests showed that the best performance was recorded for electrocatalysts with the Tafel slope values and exchange current densities that gave rise to the lowest overpotential. The study demonstrated that RDE and CV can be used to reliably assess electrocatalysts prior to full fuel cell testing. 52 refs., 3 tabs., 6 figs.

Electrochemical cell for in situ x-ray diffraction under ultrapure conditions

DEFF Research Database (Denmark)

Koop, T.; Schindler, W.; Kazimirov, A.

1998-01-01

within a few seconds. The oxygen level in the electrolyte is reduced by continuous N(2) flow to less than 0.2% compared to that of a fresh electrolyte. This can be done while rotating the cell by 360 degrees about the surface normal. The electrode potential is accurately measured at the position......An electrochemical cell has been developed for in situ x-ray diffraction from a working electrode under clean conditions equivalent to ultrahigh vacuum conditions of 5 x 10(-10) mbar. The substrate crystals can be prepared ex situ and transferred into the cell under protection of ultrapure water...... of the crystal using a Luggin capillary and a standard reference electrode. We demonstrate the performance of our cell by in situ synchrotron x-ray diffraction measurements on ultrathin Co layers electrodeposited on Cu(001) in an aqueous H(2)SO(4)/CoSO(4) solution. (C) 1998 American Institute of Physics....

Sulfur Poisoning of the Water Gas Shift Reaction on Anode Supported Solid Oxide Fuel Cells

DEFF Research Database (Denmark)

Hagen, Anke

2013-01-01

resistance increased both in the high and low frequency region, which indicates a strong poisoning of the water gas shift reaction and thus a lack of hydrogen fuel in addition to the poisoning of the electrochemical hydrogen oxidation. All poisoning effects are reversible under the applied operating...

Electrochemical Hydrogen Evolution

DEFF Research Database (Denmark)

Laursen, A.B.; Varela Gasque, Ana Sofia; Dionigi, F.

2012-01-01

The electrochemical hydrogen evolution reaction (HER) is growing in significance as society begins to rely more on renewable energy sources such as wind and solar power. Thus, research on designing new, inexpensive, and abundant HER catalysts is important. Here, we describe how a simple experiment...... catalysts based on this. Suited for upper-level high school and first-year university students, this exercise involves using a basic two-cell electrochemical setup to test multiple electrode materials as catalysts at one applied potential, and then constructing a volcano curve with the resulting currents...

Evaluation of Metals (Al, Fe, Zn) in Alternative Fuels by Electrochemical Impedance Spectroscopy in Two Electrode Cell

International Nuclear Information System (INIS)

Song, Yon Kyun; Lim, Geun Woong; Kim, Hee San

2010-01-01

Many kinds of alternative fuels such as biodiesel, ethanol, methanol, and natural gas have been developed in order to overcome the limited deposits in fossil fuels. In some cases, the alternative fuels have been reported to cause degrade materials. The corrosion rates of metals were measured by immersion test, a kind of time consuming test because low conductivity of these fuels was not allowed to employ electrochemical tests. With twin two-electrode cell newly designed for the study, however, electrochemical impedance spectroscopy (EIS) test was successfully applied to evaluation of the corrosion resistance (R p ) of zinc, iron, aluminum, and its alloys in an oxidized biodiesel and gasoline/ethanol solutions and the corrosion resistance from EIS was compared with the corrosion rate from immersion test. In biodiesel, R p increased in the order of zinc, iron, and aluminum, which agreed with the corrosion resistance measured from immersion test. In addition, on aluminum showing the best corrosion resistance (R p ), the effect of magnesium as an alloying element was evaluated in gasoline/ethanol solutions as well as the oxidized biodiesel. R p increased with addition of magnesium in gasoline/ethanol solutions containing chloride and the oxidized biodiesel. In the mean while, in gasoline/ethanol solutions containing formic acid, Al-Mg alloy added 1% magnesium had the highest R p and the further addition of magnesium decreased R p . It can be explained with the fact that the addition of more than 1% magnesium increases the passive current density of Al-Mg alloys

Electrochemical Characterization of Ni/(Sc)YSZ Electrodes

DEFF Research Database (Denmark)

Ramos, Tania; Thydén, Karl Tor Sune; Mogensen, Mogens Bjerg

2010-01-01

Investigations of Ni/(Sc)YSZ cermets for solid oxide cells (SOCs) were performed by electrochemical impedance spectroscopy (EIS), under varying experimental conditions and upon redox cycling, using three different designs of symmetric cells. The deconvolution and fitting of the obtained impedance...... parameters. Initial degradation results for both Ni/ScYSZ and Ni/YSZ based anodes under very high steam content are also reported. ©2010 COPYRIGHT ECS - The Electrochemical Society...

Light-Regulated Electrochemical Sensor Array for Efficiently Discriminating Hazardous Gases.

Science.gov (United States)

Liang, Hongqiu; Zhang, Xin; Sun, Huihui; Jin, Han; Zhang, Xiaowei; Jin, Qinghui; Zou, Jie; Haick, Hossam; Jian, Jiawen

2017-10-27

Inadequate detection limit and unsatisfactory discrimination features remain the challenging issues for the widely applied electrochemical gas sensors. Quite recently, we confirmed that light-regulated electrochemical reaction significantly enhanced the electrocatalytic activity, and thereby can potentially extend the detection limit to the parts per billion (ppb) level. Nevertheless, impact of the light-regulated electrochemical reaction on response selectivity has been discussed less. Herein, we systematically report on the effect of illumination on discrimination features via design and fabrication of a light-regulated electrochemical sensor array. Upon illumination (light on), response signal to the examined gases (C 3 H 6 , NO, and CO) is selectively enhanced, resulting in the sensor array demonstrating disparate response patterns when compared with that of the sensor array operated at light off. Through processing all the response patterns derived from both light on and light off with a pattern recognition algorithm, a satisfactory discrimination feature is observed. In contrast, apparent mutual interference between NO and CO is found when the sensor array is solely operated without illumination. The impact mechanism of the illumination is studied and it is deduced that the effect of the illumination on the discriminating features can be mainly attributed to the competition of electrocatalytic activity and gas-phase reactivity. If the enhanced electrocatalytic activity (to specific gas) dominates the whole sensing progress, enhancements in the corresponding response signal would be observed upon illumination. Otherwise, illumination gives a negligible impact. Hence, the response signal to part of the examined gases is selectively enhanced by illumination. Conclusively, light-regulated electrochemical reaction would provide an efficient approach to designing future smart sensing devices.

Designer interphases for the lithium-oxygen electrochemical cell

KAUST Repository

Choudhury, Snehashis

2017-04-20

An electrochemical cell based on the reversible oxygen reduction reaction: 2Li+ + 2e− + O2 ↔ Li2O2, provides among the most energy dense platforms for portable electrical energy storage. Such Lithium-Oxygen (Li-O2) cells offer specific energies competitive with fossil fuels and are considered promising for electrified transportation. Multiple, fundamental challenges with the cathode, anode, and electrolyte have limited practical interest in Li-O2 cells because these problems lead to as many practical shortcomings, including poor rechargeability, high overpotentials, and specific energies well below theoretical expectations. We create and study in-situ formation of solid-electrolyte interphases (SEIs) based on bromide ionomers tethered to a Li anode that take advantage of three powerful processes for overcoming the most stubborn of these challenges. The ionomer SEIs are shown to protect the Li anode against parasitic reactions and also stabilize Li electrodeposition during cell recharge. Bromine species liberated during the anchoring reaction also function as redox mediators at the cathode, reducing the charge overpotential. Finally, the ionomer SEI forms a stable interphase with Li, which protects the metal in high Gutmann donor number liquid electrolytes. Such electrolytes have been reported to exhibit rare stability against nucleophilic attack by Li2O2 and other cathode reaction intermediates, but also react spontaneously with Li metal anodes. We conclude that rationally designed SEIs able to regulate transport of matter and ions at the electrolyte/anode interface provide a promising platform for addressing three major technical barriers to practical Li-O2 cells.

Designer interphases for the lithium-oxygen electrochemical cell

KAUST Repository

Choudhury, Snehashis; Wan, Charles Tai-Chieh; Al Sadat, Wajdi I.; Tu, Zhengyuan; Lau, Sampson; Zachman, Michael J.; Kourkoutis, Lena F.; Archer, Lynden A.

2017-01-01

An electrochemical cell based on the reversible oxygen reduction reaction: 2Li+ + 2e− + O2 ↔ Li2O2, provides among the most energy dense platforms for portable electrical energy storage. Such Lithium-Oxygen (Li-O2) cells offer specific energies competitive with fossil fuels and are considered promising for electrified transportation. Multiple, fundamental challenges with the cathode, anode, and electrolyte have limited practical interest in Li-O2 cells because these problems lead to as many practical shortcomings, including poor rechargeability, high overpotentials, and specific energies well below theoretical expectations. We create and study in-situ formation of solid-electrolyte interphases (SEIs) based on bromide ionomers tethered to a Li anode that take advantage of three powerful processes for overcoming the most stubborn of these challenges. The ionomer SEIs are shown to protect the Li anode against parasitic reactions and also stabilize Li electrodeposition during cell recharge. Bromine species liberated during the anchoring reaction also function as redox mediators at the cathode, reducing the charge overpotential. Finally, the ionomer SEI forms a stable interphase with Li, which protects the metal in high Gutmann donor number liquid electrolytes. Such electrolytes have been reported to exhibit rare stability against nucleophilic attack by Li2O2 and other cathode reaction intermediates, but also react spontaneously with Li metal anodes. We conclude that rationally designed SEIs able to regulate transport of matter and ions at the electrolyte/anode interface provide a promising platform for addressing three major technical barriers to practical Li-O2 cells.

Intracellular pH is a tightly controlled signal in yeast

NARCIS (Netherlands)

Orij, R.; Brul, S.; Smits, G.J.

2011-01-01

Background: Nearly all processes in living cells are pH dependent, which is why intracellular pH (pHi) is a tightly regulated physiological parameter in all cellular systems. However, in microbes such as yeast, pHi responds to extracellular conditions such as the availability of nutrients. This

Electrochemical and photoelectrochemical reduction of furfurals

Energy Technology Data Exchange (ETDEWEB)

Choi, Kyoung-Shin; Roylance, John James; Kubota, Stephen R.

2018-02-06

Electrochemical cells and photoelectrochemical cells for the reduction of furfurals are provided. Also provided are methods of using the cells to carry out the reduction reactions. Using the cells and methods, furfurals can be converted into furan alcohols or linear ketones.

Electrochemical Analysis of Neurotransmitters

Science.gov (United States)

Bucher, Elizabeth S.; Wightman, R. Mark

2015-07-01

Chemical signaling through the release of neurotransmitters into the extracellular space is the primary means of communication between neurons. More than four decades ago, Ralph Adams and his colleagues realized the utility of electrochemical methods for the study of easily oxidizable neurotransmitters, such as dopamine, norepinephrine, and serotonin and their metabolites. Today, electrochemical techniques are frequently coupled to microelectrodes to enable spatially resolved recordings of rapid neurotransmitter dynamics in a variety of biological preparations spanning from single cells to the intact brain of behaving animals. In this review, we provide a basic overview of the principles underlying constant-potential amperometry and fast-scan cyclic voltammetry, the most commonly employed electrochemical techniques, and the general application of these methods to the study of neurotransmission. We thereafter discuss several recent developments in sensor design and experimental methodology that are challenging the current limitations defining the application of electrochemical methods to neurotransmitter measurements.

Electrochemical Dissolution of Iridium and Iridium Oxide Particles in Acidic Media: Transmission Electron Microscopy, Electrochemical Flow Cell Coupled to Inductively Coupled Plasma Mass Spectrometry, and X-ray Absorption Spectroscopy Study.

Science.gov (United States)

Jovanovič, Primož; Hodnik, Nejc; Ruiz-Zepeda, Francisco; Arčon, Iztok; Jozinović, Barbara; Zorko, Milena; Bele, Marjan; Šala, Martin; Šelih, Vid Simon; Hočevar, Samo; Gaberšček, Miran

2017-09-13

Iridium-based particles, regarded as the most promising proton exchange membrane electrolyzer electrocatalysts, were investigated by transmission electron microscopy and by coupling of an electrochemical flow cell (EFC) with online inductively coupled plasma mass spectrometry. Additionally, studies using a thin-film rotating disc electrode, identical location transmission and scanning electron microscopy, as well as X-ray absorption spectroscopy have been performed. Extremely sensitive online time-and potential-resolved electrochemical dissolution profiles revealed that Ir particles dissolve well below oxygen evolution reaction (OER) potentials, presumably induced by Ir surface oxidation and reduction processes, also referred to as transient dissolution. Overall, thermally prepared rutile-type IrO 2 particles are substantially more stable and less active in comparison to as-prepared metallic and electrochemically pretreated (E-Ir) analogues. Interestingly, under OER-relevant conditions, E-Ir particles exhibit superior stability and activity owing to the altered corrosion mechanism, where the formation of unstable Ir(>IV) species is hindered. Due to the enhanced and lasting OER performance, electrochemically pre-oxidized E-Ir particles may be considered as the electrocatalyst of choice for an improved low-temperature electrochemical hydrogen production device, namely a proton exchange membrane electrolyzer.

Electrochemical Synthesis of Ammonia from Water and Nitrogen using a Pt/GDC/Pt Cell

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong Nam; Yoo, Chung-Yul; Joo, Jong Hoon; Yu, Ji Haeng; Sharma, Monika; Yoon, Hyung Chul [Korea Institute of Energy Research, Daejeon (Korea, Republic of); Jeoung, Hana; Song, Ki Chang [Konyang University, Nonsan (Korea, Republic of)

2014-02-15

Electrochemical ammonia synthesis from water and nitrogen using a Pt/GDC/Pt cell was experimentally investigated. Electrochemical analysis and ammonia synthesis in the moisture-saturated nitrogen environment were performed under the operating temperature range 400-600 .deg. C and the applied potential range OCV (Open Circuit Voltage)-1.2V. Even though the ammonia synthesis rate was augmented with the increase in the operating temperature (i.e.. increase in the applied current) under the constant potential, the faradaic efficiency was decreased because of the limitation of dissociative chemisorption of nitrogen on the Pt electrode. The maximum synthesis rate of ammonia was 3.67x10{sup -11} mols{sup -1}cm{sup -2} with 0.1% faradaic efficiency at 600 .deg. C.

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

Science.gov (United States)

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

1989-01-01

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.

Fuel cell membrane humidification

Science.gov (United States)

Wilson, Mahlon S.

1999-01-01

A polymer electrolyte membrane fuel cell assembly has an anode side and a cathode side separated by the membrane and generating electrical current by electrochemical reactions between a fuel gas and an oxidant. The anode side comprises a hydrophobic gas diffusion backing contacting one side of the membrane and having hydrophilic areas therein for providing liquid water directly to the one side of the membrane through the hydrophilic areas of the gas diffusion backing. In a preferred embodiment, the hydrophilic areas of the gas diffusion backing are formed by sewing a hydrophilic thread through the backing. Liquid water is distributed over the gas diffusion backing in distribution channels that are separate from the fuel distribution channels.

Impact of the spatial distribution of morphological pattern on the efficiency of electrocatalytic gas evolving reactions

Directory of Open Access Journals (Sweden)

Žerađanin Aleksandar R.

2014-01-01

Full Text Available The efficiency of electrocatalytic gas evolving reactions (hydrogen, chlorine and oxygen evolution is a key challenge for the important industrial processes, such as chlor-alkali electrolysis or water electrolysis. Central issue for the aforementioned electrocatalytic processes is huge power consumption. Experimental results accumulated in the past, as well as some predictive models ("volcano" plots indicate that altering the nature of the electrode material cannot significantly increase the activity of mentioned reactions. Consequently, it is necessary to find a qualitatively different strategy for improving the energy efficiency of electrocatalytic gas evolving reactions. Usually disregarded fact is that the gas evolution is an oscillatory phenomenon. Given the oscillatory behavior, a key parameter of macrokinetics of gas electrode is the frequency of gas-bubble detachment. Bearing in mind that the gas evolution greatly depends on the surface morphology, a methodology is proposed that establishes a rational link between the morphological pattern of electrode with electrode activity and stability. Characterization was performed using advanced analytical tools. Frequency of gas-bubble detachment is obtained in the configuration of scanning electrochemical microscopy (SECM while the corrosion stability is analyzed using miniaturized scanning flow electrochemical cell connected to the mass spectrometer (SFC-ICPMS.

Technology-base research project for electrochemical storage report for 1981

Science.gov (United States)

McLarnon, F.

1982-06-01

The technology base research (TBR) project which provides the applied reseach base that supports all electrochemical energy storage applications: electric vehicles, electric load leveling, storage of solar electricity, and energy and resource conservation is described. The TBR identifies electrochemical technologies with the potential to satisfy stringent performance and economic requirements and transfer them to industry for further development and scale up. The TBR project consists of four major elements: electrochemical systems research, supporting research, electrochemical processes, and fuel cells for transportation. Activities in these four project elements during 1981 are summarized. Information is included on: iron-air batteries; aluminum-air batteries; lithium-metal sulfide cells; materials development for various batteries; and the characteristics of an NH3-air alkaline fuel cell in a vehicle.

Frumkin–Butler–Volmer Theory and Mass Transfer in Electrochemical Cells1

NARCIS (Netherlands)

Van Soestbergen, M.

2012-01-01

An accurate mathematical description of the charge transfer rate at electrodes due to an electrochemical reaction is an indispensable component of any electrochemical model. In the current work we use the generalized Frumkin-Butler–Volmer (gFBV) equation to describe electrochemical reactions, an

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

Science.gov (United States)

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

2000-01-01

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.

Monitoring programmed cell death of living plant tissues in microfluidics using electrochemical and optical techniques

DEFF Research Database (Denmark)

Mark, Christina; Heiskanen, Arto; Svensson, Birte

Programmed cell death (PCD) in plants can influence the outcome of yield and quality of crops through its important role in seed germination and the defence process against pathogens. The main scope of the project is to apply microfluidic cell culture for the measurement of electrochemically......, since it is known that reactive oxygen species, which are affected by changes in the redox activity of the cells3, are involved in PCD in plants, but the relationship between and mechanisms behind ROS and PCD is only poorly understood in plant cells4. Recently, it has been shown, using optical detection...

Rapid hydrogen charging on metal hydride negative electrode of Fuel Cell/Battery (FCB) systems

Energy Technology Data Exchange (ETDEWEB)

Choi, Bokkyu; Lee, Sunmook; Kawai, Hiroyuki; Fushimi, Chihiro; Tsutsumi, Atsushi [Collaborative Research Center for Energy Engineering, Institute of Industrial Science, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8505 (Japan)

2009-02-15

The characteristics of rapid gaseous H{sub 2} charging/electrochemical discharging of the metal hydride negative electrode were investigated for the application in Fuel Cell/Battery (FCB) systems. They were evaluated with the H{sub 2} gas absorption, followed by the subsequent electrochemical discharging in the electrolyte solution (6M KOH). Then, the cyclability of charge-discharge was also examined. It was observed that more than 70% of the theoretical capacity was charged within 10 min with 0.3 MPa and 0.5 MPa of the initial H{sub 2} pressures. The electrochemical discharge curve showed that more than 86% of the absorbed H{sub 2} was discharged. Furthermore, the cycled charge-discharge process indicated that the H{sub 2} gas charge and electrochemical discharge process is an effective way to rapidly charge and activate the metal hydride without degeneration. (author)

Bifurcation and stability of forced convection in tightly coiled ducts: multiplicity

International Nuclear Information System (INIS)

Wang Liqiu; Pang, Ophelia; Cheng Lin

2005-01-01

A numerical study is made on the fully developed bifurcation structure of the forced convection in tightly coiled ducts of square cross-section. In addition to the examination of structural changes of three known solution branches found in loosely coiled ducts, three new solution branches are found. These new branches are isolated from the three known branches. The flows on these new branches are in a symmetric 4-cell state, a symmetric 8-cell state, an asymmetric 2-cell state, an asymmetric 5-cell state, an asymmetric 7-cell state, or an asymmetric 8-cell structure

Novel quasi-symmetric solid oxide fuel cells with enhanced electrochemical performance

KAUST Repository

Chen, Yonghong

2016-02-16

Symmetrical solid oxide fuel cell (SSOFC) using same materials as both anode and cathode simultaneously has gained extensively attentions, which can simplify fabrication process, minimize inter-diffusion between components, enhance sulfur and coking tolerance by operating the anode as the cathode in turn. With keeping the SSOFC\\'s advantages, a novel quasi-symmetrical solid oxide fuel cell (Q-SSOFC) is proposed to further improve the performance, which optimally combines two different SSOFC electrode materials as both anode and cathode simultaneously. PrBaFe2O5+δ (PBFO) and PrBaFe1.6Ni0.4O5+δ (PBFNO, Fe is partially substituted by Ni.) are prepared and applied as both cathode and anode for SSOFC, which exhibit desirable chemical and thermal compatibility with Sm0.8Ce0.2O1.9 (SDC) electrolyte. PBFO cathode exhibits higher oxygen reduction reaction (ORR) activity than PBFNO cathode in air, whereas PBFNO anode exhibits higher hydrogen oxidation reaction (HOR) activity than PBFO anode in H2. The as-designed Q-SSOFC of PBFNO/SDC/PBFO exhibits higher electrochemical performance than the conventional SSOFCs of both PBFO/SDC/PBFO and PBFNO/SDC/PBFNO. The superior performance of Q-SSOFC is attributed to the lowest polarization resistance (Rp). The newly developed Q-SSOFCs open doors for further improvement of electrochemical performance in SSOFC, which hold more promise for various potential applications. © 2016 Elsevier B.V. All rights reserved.

A fast simulation tool for evaluation of novel well stimulation techniques for tight gas reservoirs

NARCIS (Netherlands)

Egberts, P.J.P.; Peters, E.

2015-01-01

For stimulation of tight fields, alternatives to hydraulic fracturing based on hydraulic jetting are becoming available. With hydraulic jetting many (10 to 20) laterals can be created in a (sub-) vertical well. The laterals are 100 to 200 m long, typically 4 laterals are applied with a small

Droplet electrochemical study of the pH dependent redox behavior of novel ferrocenyl-carborane derivatives and its application in specific cancer cell recognition

Energy Technology Data Exchange (ETDEWEB)

Wu, Changyu [State Key Laboratory of Bioelectronics (Chien-Shiung Wu Laboratory), Southeast University, Nanjing 210096 (China); Shah, Afzal [Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Ye, Hongde [State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093 (China); Chen, Xiao; Ye, Jing; Jiang, Hui [State Key Laboratory of Bioelectronics (Chien-Shiung Wu Laboratory), Southeast University, Nanjing 210096 (China); Chen, Baoan [Department of Hematology, the Affiliated Zhongda Hospital, Clinical Medical School, Southeast University, Nanjing 210009 (China); Wang, Xuemei, E-mail: xuewang@seu.edu.cn [State Key Laboratory of Bioelectronics (Chien-Shiung Wu Laboratory), Southeast University, Nanjing 210096 (China); Yan, Hong, E-mail: hyan1965@nju.edu.cn [State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093 (China)

2015-02-01

Highlights: • Electrochemical behaviors of novel ferrocenyl based carboranes (FcCB) were explored with a droplet system. • The shifts of peak potentials with changes of pH values indicated the involvement of proton during electron transfer reaction. • Normal cells and cancer cells could be specifically recognized by using FcCB as probe. • This electrochemical method in a droplet shows great potential application for relevant diagnostics of clinical samples. - Abstract: Novel ferrocenyl based carboranes (FcCBs) and their distinguish behavior for cancer cell recognition have been explored in this contribution. The voltammetric study in a droplet of 10 μL placed on the surface of a glassy carbon electrode demonstrates the excellent electrochemical behavior of FcCBs, which could be further exploited for establishing the promising and sensitive biosensors. The FcCBs’ redox behavior is examined in a wide pH range, and square wave voltammetry revealed the reversible and irreversible nature of first and second anodic peaks. The obvious shifts in peak potentials corresponding with the change of pH values demonstrate the abstraction of electrons to be accompanied with the transfer of protons. By using the droplet electrochemical technique, FcCBs can be employed to distinguish normal and cancer cells with a linear range from 1.0 × 10{sup 3} to 3.0 × 10{sup 4} cells mL{sup −1} and the limit of detection at 800 cells mL{sup −1}. The novel carborane derivatives could be utilized as important potential molecular probes for specific recognition of cancer cells like leukemia cells from normal cells.

The effect of electrodeposition process parameters on the current density distribution in an electrochemical cell

Directory of Open Access Journals (Sweden)

R. M. STEVANOVIC

2001-02-01

Full Text Available Cell voltage – current density dependences for a model electrochemical cell of fixed geometry were calculated for different electrolyte conductivities, Tafel slopes and cathodic exchange current densities. The ratio between the current density at the part of the cathode nearest to the anode and the one furthest away were taken as a measure for the estimation of the current density distribution. The calculations reveal that increasing the conductivity of the electrolyte, as well as increasing the cathodic Tafel slope should both improve the current density distribution. Also, the distribution should be better under total activation control or total diffusion control rather than at mixed activation-diffusion-Ohmic control of the deposition process. On the contrary, changes in the exchange current density should not affect it. These results, being in agreement with common knowledge about the influence of different parameters on the current distribution in an electrochemical cell, demonstrate that a quick estimation of the current distribution can be performed by a simple comparison of the current density at the point of the cathode closest to anode with that at furthest point.

Fast electrochemical actuator

International Nuclear Information System (INIS)

Uvarov, I V; Postnikov, A V; Svetovoy, V B

2016-01-01

Lack of fast and strong microactuators is a well-recognized problem in MEMS community. Electrochemical actuators can develop high pressure but they are notoriously slow. Water electrolysis produced by short voltage pulses of alternating polarity can overcome the problem of slow gas termination. Here we demonstrate an actuation regime, for which the gas pressure is relaxed just for 10 μs or so. The actuator consists of a microchamber filled with the electrolyte and covered with a flexible membrane. The membrane bends outward when the pressure in the chamber increases. Fast termination of gas and high pressure developed in the chamber are related to a high density of nanobubbles in the chamber. The physical processes happening in the chamber are discussed so as problems that have to be resolved for practical applications of this actuation regime. The actuator can be used as a driving engine for microfluidics. (paper)

Systems, methods and computer-readable media to model kinetic performance of rechargeable electrochemical devices

Science.gov (United States)

Gering, Kevin L.

2013-01-01

A system includes an electrochemical cell, monitoring hardware, and a computing system. The monitoring hardware samples performance characteristics of the electrochemical cell. The computing system determines cell information from the performance characteristics. The computing system also analyzes the cell information of the electrochemical cell with a Butler-Volmer (BV) expression modified to determine exchange current density of the electrochemical cell by including kinetic performance information related to pulse-time dependence, electrode surface availability, or a combination thereof. A set of sigmoid-based expressions may be included with the modified-BV expression to determine kinetic performance as a function of pulse time. The determined exchange current density may be used with the modified-BV expression, with or without the sigmoid expressions, to analyze other characteristics of the electrochemical cell. Model parameters can be defined in terms of cell aging, making the overall kinetics model amenable to predictive estimates of cell kinetic performance along the aging timeline.

Electrochemical oxidation of organic waste

International Nuclear Information System (INIS)

Almon, A.C.; Buchanan, B.R.

1990-01-01

Both silver catalyzed and direct electrochemical oxidation of organic species are examined in analytical detail. This paper describes the mechanisms, reaction rates, products, intermediates, capabilities, limitations, and optimal reaction conditions of the electrochemical destruction of organic waste. A small bench-top electrocell being tested for the treatment of small quantities of laboratory waste is described. The 200-mL electrochemical cell used has a processing capacity of 50 mL per day, and can treat both radioactive and nonradioactive waste. In the silver catalyzed process, Ag(I) is electrochemically oxidized to Ag(II), which attacks organic species such as tributylphosphate (TBP), tetraphenylborate (TPB), and benzene. In direct electrochemical oxidation, the organic species are destroyed at the surface of the working electrode without the use of silver as an electron transfer agent. This paper focuses on the destruction of tributylphosphate (TBP), although several organic species have been destroyed using this process. The organic species are converted to carbon dioxide, water, and inorganic acids

Electrochemical Noise Sensors for Detection of Localized and General Corrosion of Natural Gas Transmission Pipelines. Final Report for the Period July 2001-October 2002

Energy Technology Data Exchange (ETDEWEB)

Bullard, Sophie J.; Covino, Jr., Bernard S.; Russell, James H.; Holcomb, Gordon R.; Cramer, Stephen D.; Ziomek-Moroz, Margaret

2002-12-01

The U.S. Department of Energy, National Energy Technology Laboratory funded a Natural Gas Infrastructure Reliability program directed at increasing and enhancing research and development activities in topics such as remote leak detection, pipe inspection, and repair technologies and materials. The Albany Research Center (ARC), U.S. Department of Energy was funded to study the use of electrochemical noise sensors for detection of localized and general corrosion of natural gas transmission pipelines. As part of this, ARC entered into a collaborative effort with the corrosion sensor industry to demonstrate the capabilities of commercially available remote corrosion sensors for use with the Nation's Gas Transmission Pipeline Infrastructure needs. The goal of the research was to develop an emerging corrosion sensor technology into a monitor for the type and degree of corrosion occurring at key locations in gas transmission pipelines.

Analysis of Differences in Void Coefficient Predictions for Mixed-Oxide-Fueled Tight-Pitch Light Water Reactor Cells

International Nuclear Information System (INIS)

Unesaki, Hironobu; Shiroya, Seiji; Kanda, Keiji; Cathalau, Stephane; Carre, Franck-Olivier; Aizawa, Otohiko; Takeda, Toshikazu

2000-01-01

Analysis of the benchmark problems on the void coefficient of mixed-oxide (MOX)-fueled tight-pitch cells has been performed using the Japanese SRAC code system with the JENDL-3.2 library and the French APOLLO-2 code with the CEA93 library based on JEF-2.2. The benchmark problems have been specified to investigate the physical phenomena occurring during the progressive voidage of MOX-fueled tight-pitch lattices, such as high conversion light water reactor lattices, and to evaluate the impact of nuclear data and calculational methods. Despite the most recently compiled nuclear data libraries and the sophisticated calculation schemes employed in both code systems, the k ∞ and void reactivity values obtained by the two code systems show considerable discrepancy especially in the highly voided state. The discrepancy of k ∞ values shows an obvious dependence on void fraction and also has been shown to be sensitive to the isotopic composition of plutonium. The observed discrepancies are analyzed by being decomposed into contributing isotopes and reactions and have been shown to be caused by a complicated balance of both negative and positive components, which are mainly attributable to differences in a limited number of isotopes including 239 Pu, 241 Pu, 16 O, and stainless steel

High Temperature Polymer Electrolyte Fuel Cells

DEFF Research Database (Denmark)

Fleige, Michael

This thesis presents the development and application of electrochemical half-cell setups to study the catalytic reactions taking place in High Temperature Polymer Electrolyte Fuel Cells (HTPEM-FCs): (i) a pressurized electrochemical cell with integrated magnetically coupled rotating disk electrode...... oxidation of ethanol is in principle a promising concept to supply HTPEM-FCs with a sustainable and on large scale available fuel (ethanol from biomass). However, the intermediate temperature tests in the GDE setup show that even on Pt-based catalysts the reaction rates become first significant...... at potentials, which approach the usual cathode potentials of HTPEM-FCs. Therefore, it seems that H3PO4-based fuel cells are not much suited to efficiently convert ethanol in accordance with findings in earlier research papers. Given that HTPEM-FCs can tolerate CO containing reformate gas, focusing research...

Detection of gas-permeable fuel particles for highl 7490 temperature gas-cooled reactors

International Nuclear Information System (INIS)