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Sample records for lateral diffusion electrodes

  1. Foam Based Gas Diffusion Electrodes for Reversible Alkaline Electrolysis Cells

    DEFF Research Database (Denmark)

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

    2014-01-01

    cell. In the present work we demonstrate the application of hydrophobic, porous, and electro-catalytically active gas diffusion electrodes. PTFE particles and silver nanowires as electro-catalysts were used in the gas diffusion electrodes. Impedance spectroscopy and cyclic voltammetry were performed...

  2. Foam Based Gas Diffusion Electrodes for Reversible Alkaline Electrolysis Cells

    DEFF Research Database (Denmark)

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

    2014-01-01

    to the gas diffusion electrodes. A dispersion with PTFE particles of a particle size of about 1 µm in combination with electro-catalysts, such as silver nanotubes, was used to coat the gas diffusion electrodes. Impedance spectroscopy and cyclic voltammetry measurements were performed to determine...

  3. Coupled diffusion and mechanics in battery electrodes

    Science.gov (United States)

    Eshghinejad, Ahmadreza

    We are living in a world with continuous production and consumption of energy. The energy production in the past decades has started to move away from petrochemical sources toward sustainable sources such as solar, wind and geothermal. Also, the energy consumption is further adapting to the sustainable sources. For instance, in recent years electric vehicles are growing fast that can consume sustainable electric energy stored in their batteries. In this direction, in order to further move toward sustainable energy, materials are becoming increasingly important for storing electric energy. Although, currently the technologies such as Li-ion batteries and solid-oxide fuel cells are commercially available for energy applications, improvements are crucial for the next generation of many other technologies producing or consuming sustainable energies. A critical aspect of the electrochemical activities involved in energy storage technologies such as Li-ion batteries and solid-oxide fuel cells is the diffusion of ions into the electrode materials. This process ultimately governs various functional properties of the batteries such as capacity and charging/discharging rates. The first goal of this dissertation is to develop mathematical tools to analyze the ionic diffusion and investigate its coupling with mechanics in electrodes. For this purpose, a thermodynamics-based modeling framework is developed and numerically solved using two numerical methods to analyze ionic diffusion in heterogeneous and structured electrodes. The next goal of this dissertation is to develop and analyze characterization techniques to probe the electrochemical processes at the nano-scale. To this end, the mathematical models are first employed to model a previously developed Atomic Force Microscopy based technique to probe local electrochemical activities called Electrochemical Strain Microscopy (ESM). This method probes the activities by inducing AC electric field to perturb ionic activities and

  4. Penetration and lateral diffusion characteristics of polycrystalline graphene barriers

    Science.gov (United States)

    Yoon, Taeshik; Mun, Jeong Hun; Cho, Byung Jin; Kim, Taek-Soo

    2013-12-01

    We report penetration and lateral diffusion behavior of environmental molecules on synthesized polycrystalline graphene. Penetration occurs through graphene grain boundaries resulting in local oxidation. However, when the penetrated molecules diffuse laterally, the oxidation region will expand. Therefore, we measured the lateral diffusion rate along the graphene-copper interface for the first time by the environment-assisted crack growth test. It is clearly shown that the lateral diffusion is suppressed due to the high van der Waals interaction. Finally, we employed bilayer graphene for a perfect diffusion barrier facilitated by decreased defect density and increased lateral diffusion path.We report penetration and lateral diffusion behavior of environmental molecules on synthesized polycrystalline graphene. Penetration occurs through graphene grain boundaries resulting in local oxidation. However, when the penetrated molecules diffuse laterally, the oxidation region will expand. Therefore, we measured the lateral diffusion rate along the graphene-copper interface for the first time by the environment-assisted crack growth test. It is clearly shown that the lateral diffusion is suppressed due to the high van der Waals interaction. Finally, we employed bilayer graphene for a perfect diffusion barrier facilitated by decreased defect density and increased lateral diffusion path. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03849a

  5. Research on flaky and vertical gas diffusion electrode

    Institute of Scientific and Technical Information of China (English)

    朱梅; 徐献芝; 苏润; 杨基明

    2004-01-01

    Flaky and vertical gas diffusion electrode was propos, ed to improve the efficiency of fuel cells. The discharge experiments were done to compare the discharge capability of the electrode with different PTFE ingredient and different basal body uniformity. The results showed the electrode with 10% PTFE and high uniformity was favorable to discharge. This single electrode could discharge about 100 h at 150 mA(no noble metal catalyst). The electrode made of the punched screens was superior to that made of the foam Ni.

  6. Characterization of gas diffusion electrodes for metal-air batteries

    Science.gov (United States)

    Danner, Timo; Eswara, Santhana; Schulz, Volker P.; Latz, Arnulf

    2016-08-01

    Gas diffusion electrodes are commonly used in high energy density metal-air batteries for the supply of oxygen. Hydrophobic binder materials ensure the coexistence of gas and liquid phase in the pore network. The phase distribution has a strong influence on transport processes and electrochemical reactions. In this article we present 2D and 3D Rothman-Keller type multiphase Lattice-Boltzmann models which take into account the heterogeneous wetting behavior of gas diffusion electrodes. The simulations are performed on FIB-SEM 3D reconstructions of an Ag model electrode for predefined saturation of the pore space with the liquid phase. The resulting pressure-saturation characteristics and transport correlations are important input parameters for modeling approaches on the continuum scale and allow for an efficient development of improved gas diffusion electrodes.

  7. Multicomponent Gas Diffusion in Porous Electrodes

    CERN Document Server

    Fu, Yeqing; Dutta, Abhijit; Mohanram, Aravind; Pietras, John D; Bazant, Martin Z

    2014-01-01

    Multicomponent gas transport is investigated with unprecedented precision by AC impedance analysis of porous YSZ anode-supported solid oxide fuel cells. A fuel gas mixture of H2-H2O-N2 is fed to the anode, and impedance data are measured across the range of hydrogen partial pressure (10-100%) for open circuit conditions at three temperatures (800C, 850C and 900C) and for 300mA applied current at 800C. For the first time, analytical formulae for the diffusion resistance (Rb) of three standard models of multicomponent gas transport (Fick, Stefan-Maxwell, and Dusty Gas) are derived and tested against the impedance data. The tortuosity is the only fitting parameter since all the diffusion coefficients are known. Only the Dusty Gas model leads to a remarkable data collapse for over twenty experimental conditions, using a constant tortuosity consistent with permeability measurements and the Bruggeman relation. These results establish the accuracy of the Dusty Gas model for multicomponent gas diffusion in porous med...

  8. High Speed, Low Cost Fabrication of Gas Diffusion Electrodes for Membrane Electrode Assemblies

    Energy Technology Data Exchange (ETDEWEB)

    DeCastro, Emory S.; Tsou, Yu-Min; Liu, Zhenyu

    2013-09-20

    Fabrication of membrane electrode assemblies (MEAs) depends on creating inks or pastes of catalyst and binder, and applying this suspension to either the membrane (catalyst coated membrane) or gas diffusion media (gas diffusion electrode) and respectively laminating either gas diffusion media or gas diffusion electrodes (GDEs) to the membrane. One barrier to cost effective fabrication for either of these approaches is the development of stable and consistent suspensions. This program investigated the fundamental forces that destabilize the suspensions and developed innovative approaches to create new, highly stable formulations. These more concentrated formulations needed fewer application passes, could be coated over longer and wider substrates, and resulted in significantly lower coating defects. In March of 2012 BASF Fuel Cell released a new high temperature product based on these advances, whereby our customers received higher performing, more uniform MEAs resulting in higher stack build yields. Furthermore, these new materials resulted in an “instant” increase in capacity due to higher product yields and material throughput. Although not part of the original scope of this program, these new formulations have also led us to materials that demonstrate equivalent performance with 30% less precious metal in the anode. This program has achieved two key milestones in DOE’s Manufacturing R&D program: demonstration of processes for direct coating of electrodes and continuous in-line measurement for component fabrication.

  9. The sensitivity comparison of bar electrode and disposable ring electrode for recording of lateral femoral cutaneous nerve

    Directory of Open Access Journals (Sweden)

    Ahmet Z. Burakgazi

    2014-01-01

    Full Text Available Objectives: To compare the sensitivity of bar electrode and disposable ring electrode for recording of lateral femoral cutaneous (LFCN Materials and Methods: A total of 23 subjects (13 females, 10 males, mean age: 49.6 ± 9.6 (range: 29-63 were recruited in the study. A total of 36 recordings were obtained with each electrode (with bar and disposable ring electrodes from the subjects. The comparison of data was performed with percentages and student T-table test. Results: The response rate was 98% (35 out of 36 recordings with bar electrode and 88% (32 out of 36 recordings with disposable ring electrode. Although the sensitivity rate of bar electrode is slightly higher than of disposable ring electrode, there were no statistically significant differences in detecting the onset latency, peak latency, and amplitude of LFCN. Conclusion: The recording sensitivity of LFCN is higher with bar electrode than disposable ring electrode. However, disposable ring electrode can be used alternatively.

  10. Lateral diffusion on tubular membranes: quantification of measurements bias.

    Directory of Open Access Journals (Sweden)

    Marianne Renner

    Full Text Available Single Particle Tracking (SPT is a powerful technique for the analysis of the lateral diffusion of the lipid and protein components of biological membranes. In neurons, SPT allows the study of the real-time dynamics of receptors for neurotransmitters that diffuse continuously in and out synapses. In the simplest case where the membrane is flat and is parallel to the focal plane of the microscope the analysis of diffusion from SPT data is relatively straightforward. However, in most biological samples the membranes are curved, which complicates analysis and may lead to erroneous conclusions as for the mode of lateral diffusion. Here we considered the case of lateral diffusion in tubular membranes, such as axons, dendrites or the neck of dendritic spines. Monte Carlo simulations allowed us to evaluate the error in diffusion coefficient (D calculation if the curvature is not taken into account. The underestimation is determined by the diameter of the tubular surface, the frequency of image acquisition and the degree of mobility itself. We found that projected trajectories give estimates that are 25 to 50% lower than the real D in case of 2D-SPT over the tubular surface. The use of 3D-SPT improved the measurements if the frequency of image acquisition was fast enough in relation to the mobility of the molecules and the diameter of the tube. Nevertheless, the calculation of D from the components of displacements in the axis of the tubular structure gave accurate estimate of D, free of geometrical artefacts. We show the application of this approach to analyze the diffusion of a lipid on model tubular membranes and of a membrane-bound GFP on neurites from cultured rat hippocampal neurons.

  11. Lateral diffusion on tubular membranes: quantification of measurements bias.

    Science.gov (United States)

    Renner, Marianne; Domanov, Yegor; Sandrin, Fanny; Izeddin, Ignacio; Bassereau, Patricia; Triller, Antoine

    2011-01-01

    Single Particle Tracking (SPT) is a powerful technique for the analysis of the lateral diffusion of the lipid and protein components of biological membranes. In neurons, SPT allows the study of the real-time dynamics of receptors for neurotransmitters that diffuse continuously in and out synapses. In the simplest case where the membrane is flat and is parallel to the focal plane of the microscope the analysis of diffusion from SPT data is relatively straightforward. However, in most biological samples the membranes are curved, which complicates analysis and may lead to erroneous conclusions as for the mode of lateral diffusion. Here we considered the case of lateral diffusion in tubular membranes, such as axons, dendrites or the neck of dendritic spines. Monte Carlo simulations allowed us to evaluate the error in diffusion coefficient (D) calculation if the curvature is not taken into account. The underestimation is determined by the diameter of the tubular surface, the frequency of image acquisition and the degree of mobility itself. We found that projected trajectories give estimates that are 25 to 50% lower than the real D in case of 2D-SPT over the tubular surface. The use of 3D-SPT improved the measurements if the frequency of image acquisition was fast enough in relation to the mobility of the molecules and the diameter of the tube. Nevertheless, the calculation of D from the components of displacements in the axis of the tubular structure gave accurate estimate of D, free of geometrical artefacts. We show the application of this approach to analyze the diffusion of a lipid on model tubular membranes and of a membrane-bound GFP on neurites from cultured rat hippocampal neurons.

  12. 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...

  13. Lateral diffusion of nutrients by mammalian herbivores in terrestrial ecosystems.

    Directory of Open Access Journals (Sweden)

    Adam Wolf

    Full Text Available Animals translocate nutrients by consuming nutrients at one point and excreting them or dying at another location. Such lateral fluxes may be an important mechanism of nutrient supply in many ecosystems, but lack quantification and a systematic theoretical framework for their evaluation. This paper presents a mathematical framework for quantifying such fluxes in the context of mammalian herbivores. We develop an expression for lateral diffusion of a nutrient, where the diffusivity is a biologically determined parameter depending on the characteristics of mammals occupying the domain, including size-dependent phenomena such as day range, metabolic demand, food passage time, and population size. Three findings stand out: (a Scaling law-derived estimates of diffusion parameters are comparable to estimates calculated from estimates of each coefficient gathered from primary literature. (b The diffusion term due to transport of nutrients in dung is orders of magnitude large than the coefficient representing nutrients in bodymass. (c The scaling coefficients show that large herbivores make a disproportionate contribution to lateral nutrient transfer. We apply the diffusion equation to a case study of Kruger National Park to estimate the conditions under which mammal-driven nutrient transport is comparable in magnitude to other (abiotic nutrient fluxes (inputs and losses. Finally, a global analysis of mammalian herbivore transport is presented, using a comprehensive database of contemporary animal distributions. We show that continents vary greatly in terms of the importance of animal-driven nutrient fluxes, and also that perturbations to nutrient cycles are potentially quite large if threatened large herbivores are driven to extinction.

  14. Energetics of lateral eddy diffusion/advection:Part I. Thermodynamics and energetics of vertical eddy diffusion

    Institute of Scientific and Technical Information of China (English)

    HUANG Rui Xin

    2014-01-01

    Two important nonlinear properties of seawater thermodynamics linked to changes of water density, cab-beling and elasticity (compressibility), are discussed. Eddy diffusion and advection lead to changes in den-sity;as a result, gravitational potential energy of the system is changed. Therefore, cabbeling and elasticity play key roles in the energetics of lateral eddy diffusion and advection. Vertical eddy diffusion is one of the key elements in the mechanical energy balance of the global oceans. Vertical eddy diffusion can be con-ceptually separated into two steps:stirring and subscale diffusion. Vertical eddy stirring pushes cold/dense water upward and warm/light water downward;thus, gravitational potential energy is increased. During the second steps, water masses from different places mix through subscale diffusion, and water density is increased due to cabbeling. Using WOA01 climatology and assuming the vertical eddy diffusivity is equal to a constant value of 2×103 Pa2/s, the total amount of gravitational potential energy increase due to vertical stirring in the world oceans is estimated at 263 GW. Cabbeling associated with vertical subscale diffusion is a sink of gravitational potential energy, and the total value of energy lost is estimated at 73 GW. Therefore, the net source of gravitational potential energy due to vertical eddy diffusion for the world oceans is estimated at 189 GW.

  15. Hybrid Tunnel Junction-Graphene Transparent Conductive Electrodes for Nitride Lateral Light Emitting Diodes.

    Science.gov (United States)

    Wang, Liancheng; Cheng, Yan; Liu, Zhiqiang; Yi, Xiaoyan; Zhu, Hongwei; Wang, Guohong

    2016-01-20

    Graphene transparent conductive electrode (TCE) applications in nitride light emitting diodes (LEDs) are still limited by the large contact resistance and interface barrier between graphene and p-GaN. We propose a hybrid tunnel junction (TJ)-graphene TCE approach for nitride lateral LEDs theoretically and experimentally. Through simulation using commercial advanced physical models of semiconductor devices (APSYS), we found that low tunnel resistance can be achieved in the n(+)-GaN/u-InGaN/p(+)-GaN TJ, which has a lower tunneling barrier and an enhanced electric field due to the polarization effect. Graphene TCEs and hybrid graphene-TJ TCEs are then modeled. The designed hybrid TJ-graphene TCEs show sufficient current diffusion length (Ls), low introduced series resistance, and high transmittance. The assembled TJ LED with the triple-layer graphene (TLG) TCEs show comparable optoelectrical performance (3.99 V@20 mA, LOP = 10.8 mW) with the reference LED with ITO TCEs (3.36 V@20 mA, LOP = 12.6 mW). The experimental results further prove that the TJ-graphene structure can be successfully incorporated as TCEs for lateral nitride LEDs.

  16. A Mathematic Model of Gas-diffusion Electrodes in Contact with Liquid Electrolytes

    Institute of Scientific and Technical Information of China (English)

    LI Jun; XI Dan-li; SHI Yong; WU Xi-hui

    2008-01-01

    A mathematic model is developed which is applied to analyze the main factors that affect electrode performance and to account for the process of reaction and mass transfer in gas-diffusion electrodes in contact with liquid electrolytes. Electrochemical Thiele modulus φ2 and electrochemical effectiveness factor ηD are introduced to elucidate the effects of diffusion on electrochemical reaction and utilization of the gas-diffusion electrode.Profile of the reactant along axial direction is discussed,dependence of electrode potential V on current density J.are predicated by means of the newly developed mathematical model.

  17. Longitudinal diffusion tensor imaging in amyotrophic lateral sclerosis

    Directory of Open Access Journals (Sweden)

    Keil Carsten

    2012-11-01

    Full Text Available Abstract Background Amyotrophic lateral sclerosis (ALS is a fatal neurodegenerative disorder, caused by progressive loss of motor neurons. Changes are widespread in the subcortical white matter in ALS. Diffusion tensor imaging (DTI detects pathological changes in white matter fibres in vivo, based on alterations in the degree (diffusivity, ADC and directedness (fractional anisotropy, FA of proton movement. Methods 24 patients with ALS and 24 age-matched controls received 1.5T DTI. FA and ADC were analyzed using statistical parametric mapping. In 15 of the 24 ALS patients, a second DTI was obtained after 6 months. Results Decreased FA in the corticospinal tract (CST and frontal areas confirm existing results. With a direct comparison of baseline and follow-up dataset, the progression of upper motor neuron degeneration, reflected in FA decrease, could be captured along the CST and in frontal areas. The involvement of cerebellum in the pathology of ALS, as suspected from functional MRI studies, could be confirmed by a reduced FA (culmen, declive. These structural changes correlated well with disease duration, ALSFRS-R, and physical and executive functions. Conclusion DTI detects changes that are regarded as prominent features of ALS and thus, shows promise in its function as a biomarker. Using the technique herein, we could demonstrate DTI changes at follow-up which correlated well with clinical progression.

  18. Electrochemical disinfection using the gas diffusion electrode system.

    Science.gov (United States)

    Xu, Wenying; Li, Ping; Dong, Bin

    2010-01-01

    A study on the electrochemical disinfection with H2O2 generated at the gas diffusion electrode (GDE) from active carbon/polytetrafluoroethylene was performed in a non-membrane cell. The effects of Pt load and the pore-forming agent content in GDE, and operating conditions were investigated. The experimental results showed that nearly all bacterial cultures inoculated in the secondary effluent from wastewater treatment plant could be inactivated within 30 min at a current density of 10 mA/cm2. The disinfection improved with increasing Pt load. Addition of the pore-forming agent NH4HCO3 improved the disinfection, while a drop in the pH value resulted in a rapid rise of germicidal efficacy and the disinfection time was shortened with increasing oxygen flow rate. Adsorption was proved to be ineffective in destroying bacteria, while germicidal efficacy increased with current density. The acceleration rate was different, it initially increased with current density. Then decreased, and finally reached a maximum at a current density of 6.7 mA/cm2. The disinfection also improved with decreasing total bacterial count. The germicidal efficacy in the cathode compartment was approximately the same as in the anode compartment, indicating that the contribution of direct oxidation and the indirect treatment of bacterial cultures by hydroxyl radical was similar to the oxidative indirect effect of the generated H2O2.

  19. Novel high-voltage power lateral MOSFET with adaptive buried electrodes

    Institute of Scientific and Technical Information of China (English)

    Zhang Wen-Tong; Wu Li-Juan; Qiao Ming; Luo Xiao-Rong; Zhang Bo; Li Zhao-Ji

    2012-01-01

    A new high-voltage and low-specific on-resistance (Ron,sp) adaptive buried electrode (ABE) silicon-on-insulator (SOI) power lateral MOSFET and its analytical model of the electric fields are proposed.The MOSFET features are that the electrodes are in the buried oxide (BOX) layer,the negative drain voltage Vd is divided into many partial voltages and the output to the electrodes is in the buried oxide layer and the potentials on the electrodes change linearly from the drain to the source.Because the interface silicon layer potentials are lower than the neighboring electrode potentials,the electronic potential wells are formed above the electrode regions,and the hole poteutial wells are formed in the spacing of two neighbouring electrode regions.The interface hole concentration is much higher than the electron concentration through designing the buried layer electrode potentials.Based on the interface charge enhanced dielectric layer field theory,the electric field strength in the buried layer is enhanced.The vertical electric field EI and the breakdown voltage (BV) of ABE SOI are 545 V/μm and -587 V in the 50 μm long drift region and the 1 tm thick dielectric layer,and a low Ron,sp is obtained.Furthermore,the structure also alleviates the self-heating effect (SHE).The analytical model matches the simulation results.

  20. [Electrochemical disinfection using the gas diffusion electrode system].

    Science.gov (United States)

    Xu, Wen-Ying; Li, Ping; Dong, Bin

    2010-01-01

    Study on the electrochemical disinfection with the H2O2 produced at the gas diffusion electrode (GDE) prepared from active carbon/ poly-tetrafluoroethylene (PTFE) was performed in the non-membrane cell. The effects of PTFE mass fraction W(PTFE) and content of the pore-forming agent in GDE m(NH4CO3), operating conditions such as pH value and oxygen flow rate Q(o2)) on disinfection were investigated, respectively. The experimental results showed that H2 O2 reached peak production at W(PTFE) of 0.5 in GDE. Addition of the pore-forming agent in the appropriate amount improved the disinfection, and this phenomenon was more obvious at neutral pH than at acidic pH. BET specific area analysis indicated that the average pore size in the membrane electrode first decreased significantly with the increasing amount of pore-forming agent, and then increased moderately. This helped the mass transfer of oxygen at the GDE. Adsorption made little or no progress to kill the bacteria during the electrolysis. Drop of pH value resulted in a rapid rise of the germicidal efficacy. This system had a broad pH coverage: when total bacterial count in raw water was 10(6) CFU x mL(-1), pH 3-10,the germicidal efficacy was greater than 80% after 30 min electrolysis using the GDE with W(Pt) of 3 per thousand as cathode. Increase of the oxygen flow rate Q(o2) within limits had little influence on the production of H2 O2 and the succeeding disinfection. On one hand, resistance of the solution and energy consumption on the disinfection increased at high oxygen flow rate, which gave rise to an increase in the operating cost of disinfection with the GDE system; on the other hand, treatment time could be reduced reasonably at high oxygen flow rate, which leads to reduction of equipment investment. Killing mechanism study showed that the direct oxidation and formation of the free radicals at the anode played a greater role in the beginning, and then the oxidative indirect effect of the generated H2 O2 at

  1. Time of Flight Electrochemistry: Diffusion Coefficient Measurements Using Interdigitated Array (IDA) Electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fei; Kolesov, Grigory; Parkinson, Bruce A.

    2014-09-26

    A simple and straightforward method for measuring diffusion coefficients using interdigitated array (IDA) electrodes is reported. The method does not require that the exact electrode area be known but depends only the size of the gap between the IDA electrode pairs. Electroactive molecules produced at the generator electrode of the IDA by a voltage step or scan can diffuse to the collector electrode and the time delay before the current for the reverse electrochemical reaction is detected at the collector is used to calculate the diffusion coefficient. The measurement of the diffusion rate of Ru(NH3)6+2 in aqueous solution has been used as an example measuring diffusion coefficients using this method. Additionally, a digital simulation of the electrochemical response of the IDA electrodes was used to simulate the entire current/voltage/time behavior of the system and verify the experimentally measured diffusion coefficients. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the Department of Energy, Office of Science, Office of Basic Energy Sciences.

  2. Energetics of lateral eddy diffusion/advection:Part II. Numerical diffusion/diffusivity and gravitational potential energy change due to isopycnal diffusion

    Institute of Scientific and Technical Information of China (English)

    HUANG Rui Xin

    2014-01-01

    Study of oceanic circulation and climate requires models which can simulate tracer eddy diffusion and ad-vection accurately. It is shown that the traditional Eulerian coordinates can introduce large artificial hori-zontal diffusivity/viscosity due to the incorrect alignment of the axis. Therefore, such models can smear sharp fronts and introduce other numerical artifacts. For simulation with relatively low resolution, large lateral diffusion was explicitly used in models;therefore, such numerical diffusion may not be a problem. However, with the increase of horizontal resolution, the artificial diffusivity/viscosity associated with hori-zontal advection in the commonly used Eulerian coordinates may become one of the most challenging ob-stacles for modeling the ocean circulation accurately. Isopycnal eddy diffusion (mixing) has been widely used in numerical models. The common wisdom is that mixing along isopycnal is energy free. However, a careful examination reveals that this is not the case. In fact, eddy diffusion can be conceptually separated into two steps:stirring and subscale diffusion. Due to the thermobaric effect, stirring, or exchanging water masses, along isopycnal surface is associated with the change of GPE in the mean state. This is a new type of instability, called the thermobaric instability. In addition, due to cabbeling subscale diffusion of water parcels always leads to the release of GPE. The release of GPE due to isopycnal stirring and subscale diffusion may lead to the thermobaric instability.

  3. Spurious chemical diffusion coefficients of Li{sup +} in electrode materials evaluated with GITT

    Energy Technology Data Exchange (ETDEWEB)

    Diss, E. [Paul Scherrer Inst., Villagen (Switzerland)

    2005-05-05

    The galvanostatic intermittent titration technique (GITT) has been used as a standard method for evaluating chemical diffusion coefficients in electrode materials in the last three decades. It will now be demonstrated that these chemical diffusion coefficients evaluated with GITT are spurious as any reaction kinetics is neglected in the GITT theory. The neglect of the reaction kinetics leads to a spurious potential dependence of the GITT diffusion coefficients with minima at those potentials where the slow scan rate cyclic voltammogram or differential capacity plot exhibits peaks even in case where the true chemical diffusion coefficient is constant. This will be demonstrated by the evaluation of GITT diffusion coefficients from numerically generated GITT experiments calculated with a constant chemical diffusion coefficient on the example of a spinel-type LiMn{sub 2}O{sub 4} electrode. (Author)

  4. Effects of Nanoparticle Geometry and Size Distribution on Diffusion Impedance of Battery Electrodes

    CERN Document Server

    Song, J

    2012-01-01

    The short diffusion lengths in insertion battery nanoparticles render the capacitive behavior of bounded diffusion, which is rarely observable with conventional larger particles, now accessible to impedance measurements. Coupled with improved geometrical characterization, this presents an opportunity to measure solid diffusion more accurately than the traditional approach of fitting Warburg circuit elements, by properly taking into account the particle geometry and size distribution. We revisit bounded diffusion impedance models and incorporate them into an overall impedance model for different electrode configurations. The theoretical models are then applied to experimental data of a silicon nanowire electrode to show the effects of including the actual nanowire geometry and radius distribution in interpreting the impedance data. From these results, we show that it is essential to account for the particle shape and size distribution to correctly interpret impedance data for battery electrodes. Conversely, it...

  5. Application of gas diffusion electrodes in bioelectrochemical syntheses and energy conversion.

    Science.gov (United States)

    Horst, Angelika E W; Mangold, Klaus-Michael; Holtmann, Dirk

    2016-02-01

    Combining the advantages of biological components (e.g., reaction specificity, self-replication) and electrochemical techniques in bioelectrochemical systems offers the opportunity to develop novel efficient and sustainable processes for the production of a number of valuable products. The choice of electrode material has a great impact on the performance of bioelectrochemical systems. In addition to the redox process at the electrodes, interactions of biocatalysts with electrodes (e.g., enzyme denaturation or biofouling) need to be considered. In recent years, gas diffusion electrodes (GDEs) have proved to be very attractive electrodes for bioelectrochemical purposes. GDEs are porous electrodes, that posses a large three-phase boundary surface. At this interface, a solid catalyst supports the electrochemical reaction between gaseous and liquid phase. This mini-review discusses the application of GDEs in microbial and enzymatic fuel cells, for microbial electrolysis, in biosensors and for electroenzymatic synthesis reactions.

  6. Lateral convection and diffusion of sediment in straight rivers

    DEFF Research Database (Denmark)

    Christensen, Henrik Bo; Fredsøe, Jørgen

    1998-01-01

    The lateral transport of suspended sediment in a straight river cross section with a parabolic shaped bed is studied be use of a k-e and a full Reynolds stress turbulence model. Due to depth variations a lateral transport of suspended sediment is generated. This is mainly caused by the slopping bed...

  7. Lateral CO2 diffusion inside dicotyledonous leaves can be substantial: quantification in different light intensities.

    Science.gov (United States)

    Morison, James I L; Lawson, Tracy; Cornic, Gabriel

    2007-11-01

    Substantial lateral CO(2) diffusion rates into leaf areas where stomata were blocked by grease patches were quantified by gas exchange and chlorophyll a fluorescence imaging in different species across the full range of photosynthetic photon flux densities (PPFD). The lateral CO(2) flux rate over short distances was substantial and very similar in five dicotyledonous species with different vascular anatomies (two species with bundle sheath extensions, sunflower [Helianthus annuus] and dwarf bean [Phaseolus vulgaris]; and three species without bundle sheath extensions, faba bean [Vicia faba], petunia [Petunia hybrida], and tobacco [Nicotiana tabacum]). Only in the monocot maize (Zea mays) was there little or no evident lateral CO(2) flux. Lateral diffusion rates were low when PPFD saturation in moderate PPFD (300 micromol m(-2) s(-1)) when lateral CO(2) diffusion represented 15% to 24% of the normal CO(2) assimilation rate. Smaller patches and higher ambient CO(2) concentration increased lateral CO(2) diffusion rates. Calculations with a two-dimensional diffusion model supported these observations that lateral CO(2) diffusion over short distances inside dicotyledonous leaves can be important to photosynthesis. The results emphasize that supply of CO(2) from nearby stomata usually dominates assimilation, but that lateral supply over distances up to approximately 1 mm can be important if stomata are blocked, particularly when assimilation rate is low.

  8. Dynamics of the atmospheric pressure diffuse dielectric barrier discharge between cylindrical electrodes in roll-to-roll PECVD reactor

    Science.gov (United States)

    Starostin, Sergey A.; Welzel, Stefan; Liu, Yaoge; van der Velden-Schuermans, Bernadette; Bouwstra, Jan B.; van de Sanden, Mauritius C. M.; de Vries, Hindrik W.

    2015-07-01

    The high current diffuse dielectric barrier discharge (DBD) was operated in a bi-axial cylindrical electrode configuration using nitrogen, oxygen and argon gas flow with the addition of tetraethyl orthosilicate as precursor for silica-like film deposition. The behaviour of the transient plasma was visualized by means of fast imaging from two orthogonal directions. The formation and propagation (~3 × 104 m s-1) of lateral ionization waves with the transverse light emission structure similar to the low pressure glow discharge was observed at time scales below 1 µs. Despite plasma non-uniformity at nanosecond time scale the deposition process on the web-rolled polymer results in smooth well adherent films with good film uniformity and excellent gas diffusion barrier properties. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  9. Amperometric Determination of Sulfite by Gas Diffusion-Sequential Injection with Boron-Doped Diamond Electrode

    OpenAIRE

    Orawon Chailapakul; Toshihiko Imato; Narong Praphairaksit; Kulwadee Pinwattana; Chakorn Chinvongamorn

    2008-01-01

    A gas diffusion sequential injection system with amperometric detection using aboron-doped diamond electrode was developed for the determination of sulfite. A gasdiffusion unit (GDU) was used to prevent interference from sample matrices for theelectrochemical measurement. The sample was mixed with an acid solution to generategaseous sulfur dioxide prior to its passage through the donor channel of the GDU. Thesulfur dioxide diffused through the PTFE hydrophobic membrane into a carrier solution...

  10. Arcuate fasciculus laterality by diffusion tensor imaging correlates with language laterality by functional MRI in preadolescent children

    Energy Technology Data Exchange (ETDEWEB)

    Sreedharan, Ruma Madhu [Government Medical College Hospital, Department of Radiology, Trivandrum, Kerala (India); Menon, Amitha C.; Thomas, Sanjeev V. [Sree Chitra, Thirunal Institute for Medical Sciences and Technology, Department of Neurology, Thiruvananthapuram, Kerala (India); James, Jija S.; Kesavadas, Chandrasekharan [SCTIMST, Department of Imaging Science and Interventional Radiology, Trivandrum, Kerala (India)

    2015-03-01

    Language lateralization is unique to humans. Functional MRI (fMRI) and diffusion tensor imaging (DTI) enable the study of language areas and white matter fibers involved in language, respectively. The objective of this study was to correlate arcuate fasciculus (AF) laterality by diffusion tensor imaging with that by fMRI in preadolescent children which has not yet been reported. Ten children between 8 and 12 years were subjected to fMRI and DTI imaging using Siemens 1.5 T MRI. Two language fMRI paradigms - visual verb generation and word pair task - were used. Analysis was done using SPM8 software. In DTI, the fiber volume of the arcuate fasciculus (AFV) and fractional anisotropy (FA) was measured. The fMRI Laterality Index (fMRI-LI) and DTI Laterality Index (DTI-LI) were calculated and their correlation assessed using the Pearson Correlation Index. Of ten children, mean age 10.6 years, eight showed left lateralization while bilateral language lateralization was seen in two. AFV by DTI was more on the left side in seven of the eight children who had left lateralization by fMRI. DTI could not trace the AF in one child. Of the two with bilateral language lateralization on fMRI, one showed larger AFV on the right side while the other did not show any asymmetry. There was a significant correlation (p < 0.02) between fMRI-LI and DTI-LI. Group mean of AFV by DTI was higher on the left side (2659.89 ± 654.75 mm{sup 3}) as compared to the right (1824.11 ± 582.81 mm{sup 3}) (p < 0.01). Like fMRI, DTI also reveals language laterality in children with a high degree of correlation between the two imaging modalities. (orig.)

  11. Lateral diffusion of bilayer lipids measured via (31)P CODEX NMR.

    Science.gov (United States)

    Saleem, Qasim; Lai, Angel; Morales, Hannah H; Macdonald, Peter M

    2012-10-01

    We have employed (31)P CODEX (centre-band-only-detection-of-exchange) NMR to measure lateral diffusion coefficients of phospholipids in unilamellar lipid bilayer vesicles consisting of 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC), alone or in mixtures with 30 mol% 1-palmitoyl-2-oleoyl-phosphatidylglycerol (POPG) or cholesterol (CHOL). The lateral diffusion coefficients of POPC and POPG were extracted from experimental CODEX signal decays as a function of increasing mixing time, after accounting for the vesicle's size and size distribution, as determined via dynamic light scattering, and the viscosity of the vesicular suspension, as determined via (1)H pulsed field gradient NMR. Lateral diffusion coefficients for POPC and POPG determined in this fashion fell in the range 1.0-3.2 × 10(-12) m(2) s(-1) at 10 °C, depending on the vesicular composition, in good agreement with accepted values. Thus, two advantages of (31)P CODEX NMR for phospholipid lateral diffusion measurements are demonstrated: no labelling of the molecule of interest is necessary, and multiple lateral diffusion coefficients can be measured simultaneously. It is expected that this approach will prove particularly useful in diagnosing heterogeneities in lateral diffusion behaviours, such as might be expected for specific lipid-lipid or lipid-protein interactions, and thermotropic or electrostatically induced phase inhomogeneities.

  12. Investigation of Top/bottom Electrode and Diffusion Barrier Layer for PZT thick film MEMS Sensors

    DEFF Research Database (Denmark)

    Pedersen, Thomas; Hindrichsen, Christian Carstensen; Lou-Møller, R.

    2007-01-01

    In this work screen printed piezoelectric Ferroperm PZ26 lead zirconate titanate (PZT) thick film is used for two MEMS devices. A test structure is used to investigate several aspects regarding bottom and top electrodes. 450 nm ZrO2 thin film is found to be an insufficient diffusion barrier layer...

  13. Quantitating Changes in Jitter and Spike Number Using Concentric Needle Electrodes in Amyotrophic Lateral Sclerosis Patients

    Institute of Scientific and Technical Information of China (English)

    Ming-Sheng Liu; Jing-Wen Niu; Yi Li; Yu-Zhou Guan; Li-Ying Cui

    2016-01-01

    Background:Single-fiber electromyography (SFEMG) has been suggested as a quantitative method for supporting chronic partial denervation in amyotrophic lateral sclerosis (ALS) by the revised El Escorial criteria.Although concentric needle (CN) electrodes have been used to assess jitter in myasthenia gravis patients and healthy controls,there are few reports using CN electrodes to assess motor unit instability and denervation in neurogenic diseases.The aim of this study was to determine whether quantitative changes in jitter and spike number using CN electrodes could be used for ALS studies.Methods:Twenty-seven healthy controls and 23 ALS patients were studied using both CN and single-fiber needle (SFN) electrodes on the extensor digitorum communis muscle with an SFEMG program.The SFN-jitter and SFN-fiber density data were measured using SFN electrodes.The CN-jitter and spike number were measured using CN electrodes.Results:The mean CN-jitter was significantly increased in ALS patients (47.3 ± 17.0 μs) than in healthy controls (27.4 ± 3.3 μs) (P < 0.001).Besides,the mean spike number was significantly increased in ALS patients (2.5 ± 0.5) than in healthy controls (1.7 ± 0.3) (P < 0.001).The sensitivity and specificity in the diagnosis of ALS were 82.6% and 92.6% for CN-jitter (cut-off value:32 μs),and 91.3% and 96.3% for the spike number (cut-offvalue:2.0),respectively.There was no significant difference between the SFN-jitter and CN-jitter in ALS patients; meanwhile,there was no significant difference between the SFN-jitter and CN-jitter in healthy controls.Conclusion:CN-jitter and spike number could be used to quantitatively evaluate changes due to denervation-reinnervation in ALS.

  14. Calculation method for steady-state pollutant concentration in mixing zones considering variable lateral diffusion coefficient.

    Science.gov (United States)

    Wu, Wen; Wu, Zhouhu; Song, Zhiwen

    2017-07-01

    Prediction of the pollutant mixing zone (PMZ) near the discharge outfall in Huangshaxi shows large error when using the methods based on the constant lateral diffusion assumption. The discrepancy is due to the lack of consideration of the diffusion coefficient variation. The variable lateral diffusion coefficient is proposed to be a function of the longitudinal distance from the outfall. Analytical solution of the two-dimensional advection-diffusion equation of a pollutant is derived and discussed. Formulas to characterize the geometry of the PMZ are derived based on this solution, and a standard curve describing the boundary of the PMZ is obtained by proper choices of the normalization scales. The change of PMZ topology due to the variable diffusion coefficient is then discussed using these formulas. The criterion of assuming the lateral diffusion coefficient to be constant without large error in PMZ geometry is found. It is also demonstrated how to use these analytical formulas in the inverse problems including estimating the lateral diffusion coefficient in rivers by convenient measurements, and determining the maximum allowable discharge load based on the limitations of the geometrical scales of the PMZ. Finally, applications of the obtained formulas to onsite PMZ measurements in Huangshaxi present excellent agreement.

  15. Ligand binding affinity and changes in the lateral diffusion of receptor for advanced glycation endproducts (RAGE).

    Science.gov (United States)

    Syed, Aleem; Zhu, Qiaochu; Smith, Emily A

    2016-12-01

    The effect of ligand on the lateral diffusion of receptor for advanced glycation endproducts (RAGE), a receptor involved in numerous pathological conditions, remains unknown. Single particle tracking experiments that use quantum dots specifically bound to hemagglutinin (HA)-tagged RAGE (HA-RAGE) are reported to elucidate the effect of ligand binding on HA-RAGE diffusion in GM07373 cell membranes. The ligand used in these studies is methylglyoxal modified-bovine serum albumin (MGO-BSA) containing advanced glycation end products modifications. The binding affinity between soluble RAGE and MGO-BSA increases by 1.8 to 9.7-fold as the percent primary amine modification increases from 24 to 74% and with increasing negative charge on the MGO-BSA. Ligand incubation affects the HA-RAGE diffusion coefficient, the radius of confinement, and duration of confinement. There is, however, no correlation between MGO-BSA ligand binding affinity with soluble RAGE and the extent of the changes in HA-RAGE lateral diffusion. The ligand induced changes to HA-RAGE lateral diffusion do not occur when cholesterol is depleted from the cell membrane, indicating the mechanism for ligand-induced changes to HA-RAGE diffusion is cholesterol dependent. The results presented here serve as a first step in unraveling how ligand influences RAGE lateral diffusion. Copyright © 2016. Published by Elsevier B.V.

  16. Lateral Diffusion of CO2 in Leaves Is Not Sufficient to Support Photosynthesis[w

    Science.gov (United States)

    Morison, James I.L.; Gallouët, Emily; Lawson, Tracy; Cornic, Gabriel; Herbin, Raphaèle; Baker, Neil R.

    2005-01-01

    Lateral diffusion of CO2 was investigated in photosynthesizing leaves with different anatomy by gas exchange and chlorophyll a fluorescence imaging using grease to block stomata. When one-half of the leaf surface of the heterobaric species Helianthus annuus was covered by 4-mm-diameter patches of grease, the response of net CO2 assimilation rate (A) to intercellular CO2 concentration (Ci) indicated that higher ambient CO2 concentrations (Ca) caused only limited lateral diffusion into the greased areas. When single 4-mm patches were applied to leaves of heterobaric Phaseolus vulgaris and homobaric Commelina communis, chlorophyll a fluorescence images showed dramatic declines in the quantum efficiency of photosystem II electron transport (measured as Fq′/Fm′) across the patch, demonstrating that lateral CO2 diffusion could not support A. The Fq′/Fm′ values were used to compute images of Ci across patches, and their dependence on Ca was assessed. At high Ca, the patch effect was less in C. communis than P. vulgaris. A finite-volume porous-medium model for assimilation rate and lateral CO2 diffusion was developed to analyze the patch images. The model estimated that the effective lateral CO2 diffusion coefficients inside C. communis and P. vulgaris leaves were 22% and 12% of that for free air, respectively. We conclude that, in the light, lateral CO2 diffusion cannot support appreciable photosynthesis over distances of more than approximately 0.3 mm in normal leaves, irrespective of the presence or absence of bundle sheath extensions, because of the CO2 assimilation by cells along the diffusion pathway. PMID:16113223

  17. Energetics of lateral eddy diffusion/advection:Part III. Energetics of horizontal and isopycnal diffusion/advection

    Institute of Scientific and Technical Information of China (English)

    HUANG Rui Xin

    2014-01-01

    Gravitational Potential Energy (GPE) change due to horizontal/isopycnal eddy diffusion and advection is examined. Horizontal/isopycnal eddy diffusion is conceptually separated into two steps:stirring and sub-scale diffusion. GPE changes associated with these two steps are analyzed. In addition, GPE changes due to stirring and subscale diffusion associated with horizontal/isopycnal advection in the Eulerian coordinates are analyzed. These formulae are applied to the SODA data for the world oceans. Our analysis indicates that horizontal/isopycnal advection in Eulerian coordinates can introduce large artificial diffusion in the model. It is shown that GPE source/sink in isopycnal coordinates is closely linked to physical property distribution, such as temperature, salinity and velocity. In comparison with z-coordinates, GPE source/sink due to stir-ring/cabbeling associated with isopycnal diffusion/advection is much smaller. Although isopycnal coordi-nates may be a better choice in terms of handling lateral diffusion, advection terms in the traditional Eule-rian coordinates can produce artificial source of GPE due to cabbeling associated with advection. Reducing such numerical errors remains a grand challenge.

  18. Effects of electrode properties and fabricated pressure on Li ion diffusion and diffusion-induced stresses in cylindrical Li-ion batteries

    Science.gov (United States)

    Zhang, Tao; Guo, Zhansheng

    2014-03-01

    The effects of electrode properties and fabricated pressure on Li ion diffusion and diffusion-induced stress in a cylindrical Li-ion battery are studied. It is found that hydrostatic pressure or elastic modulus variation in the active layer have little effect on the distribution of Li ions for a higher diffusivity coefficient, but both can facilitate Li ion diffusion for a lower diffusivity coefficient. The elastic modulus variation has a significant effect on the distribution of stress and hydrostatic pressure can reduce the surface stress for the lower diffusivity coefficient. A higher charging rate causes a more transient response in the stress history, but a linear charging history is observed for slow charging rates. A higher charging rate would not inflict extra damage on the electrode for the higher diffusivity coefficient and the stress history becomes highly transient and charging rate dependent for the lower diffusivity coefficient. The effect of fabricated pressure can be neglected.

  19. Electrochemical degradation of 4-chlorophenol using a novel Pd/C gas-diffusion electrode

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hui; Wang, Jianlong [Laboratory of Environmental Technology, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084 (China)

    2007-11-30

    Pd/C catalyst was prepared by hydrogen reduction method and used for the Pd/C gas-diffusion electrode. It was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) techniques. The electrochemical degradation of 4-chlorophenol was investigated in a diaphragm electrolysis device, by two different feeding gas modes, using the Pd/C gas-diffusion electrode and the carbon/polytetrafluoroethylene (C/PTFE) gas-diffusion electrode as a cathode, respectively. The results indicated that Pd particles with an average size of 4.0 nm were highly dispersed in the activated carbon with an amorphous structure; Pd content on the surface of the Pd/C catalyst reached 1.3 at.%. Furthermore, feeding with hydrogen gas firstly and then with air was in favor of improving 4-chlorophenol removal efficiency. The Pd/C gas-diffusion cathode can not only reductively dechlorinate 4-chlorophenols by feeding hydrogen gas, but also accelerate the two-electron reduction of O{sub 2} to hydrogen peroxide (H{sub 2}O{sub 2}) by feeding air. Therefore, the removal efficiency of 4-chlorophenol by using the Pd/C gas-diffusion cathode was better than that of the C/PTFE gas-diffusion cathode. And both the removal efficiency and the dechlorination degree of 4-chlorophenol reached about 100% after 60 min, and the average removal efficiency of 4-chlorophenol in terms of chemical oxygen demand (COD) exceeded 70% after 120 min. The analysis of high-performance liquid chromatography (HPLC) identified that phenol was the dechlorination product, and hydroquinone, benzoquinone, maleic, fumaric, crylic, malonic, oxalic, acetic and formic acids were the main oxidation intermediates. A reaction pathway involving all these intermediates was proposed. (author)

  20. Defect Detection in Fuel Cell Gas Diffusion Electrodes Using Infrared Thermography

    Energy Technology Data Exchange (ETDEWEB)

    Ulsh, Michael; Porter, Jason M.; Bittinat, Daniel C.; Bender, Guido

    2016-04-01

    Polymer electrolyte membrane fuel cells are energy conversion devices that offer high power densities and high efficiencies for mobile and other applications. Successful introduction into the marketplace requires addressing cost barriers such as production volumes and platinum loading. For cost reduction, it is vital to minimize waste and maximize quality during the manufacturing of platinum-containing electrodes, including gas diffusion electrodes (GDEs). In this work, we report on developing a quality control diagnostic for GDEs, involving creating an ex situ exothermic reaction on the electrode surface and using infrared thermography to measure the resulting temperature profile. Experiments with a moving GDE containing created defects were conducted to demonstrate the applicability of the diagnostic for real-time web-line inspection.

  1. Limiting Current of Oxygen Reduction on Gas-Diffusion Electrodes for Phosphoric Acid Fuel Cells

    DEFF Research Database (Denmark)

    Li, Qingfeng; Gang, Xiao; Hjuler, Hans Aage;

    1994-01-01

    Various models have been devoted to the operation mechanism of porous diffusion electrodes. They are, however, suffering from the lack of accuracy concerning the acid-film thickness on which they are based. In the present paper the limiting current density has been measured for oxygen reduction...... on polytetrafluorine-ethyl bonded gas-diffusion electordes in phosphoric acid with and without fluorinated additives. This provides an alternative to estimate the film thickness by combining it with the acid-adsorption measurements and the porosity analysis of the catalyst layer. It was noticed that the limiting...... expression for the limiting current density. The acid-film thickness estimated this way was found to be of 0.1 mum order of magnitude for the two types of electrodes used in phosphoric acid with and without fluorinated additives at 150-degrees-C....

  2. Membrane orientation and lateral diffusion of BODIPY-cholesterol as a function of probe structure.

    Science.gov (United States)

    Solanko, Lukasz M; Honigmann, Alf; Midtiby, Henrik Skov; Lund, Frederik W; Brewer, Jonathan R; Dekaris, Vjekoslav; Bittman, Robert; Eggeling, Christian; Wüstner, Daniel

    2013-11-05

    Cholesterol tagged with the BODIPY fluorophore via the central difluoroboron moiety of the dye (B-Chol) is a promising probe for studying intracellular cholesterol dynamics. We synthesized a new BODIPY-cholesterol probe (B-P-Chol) with the fluorophore attached via one of its pyrrole rings to carbon-24 of cholesterol (B-P-Chol). Using two-photon fluorescence polarimetry in giant unilamellar vesicles and in the plasma membrane (PM) of living intact and actin-disrupted cells, we show that the BODIPY-groups in B-Chol and B-P-Chol are oriented perpendicular and almost parallel to the bilayer normal, respectively. B-Chol is in all three membrane systems much stronger oriented than B-P-Chol. Interestingly, we found that the lateral diffusion in the PM was two times slower for B-Chol than for B-P-Chol, although we found no difference in lateral diffusion in model membranes. Stimulated emission depletion microscopy, performed for the first time, to our knowledge, with fluorescent sterols, revealed that the difference in lateral diffusion of the BODIPY-cholesterol probes was not caused by anomalous subdiffusion, because diffusion of both analogs in the PM was free but not hindered. Our combined measurements show that the position and orientation of the BODIPY moiety in cholesterol analogs have a severe influence on lateral diffusion specifically in the PM of living cells.

  3. Membrane orientation and lateral diffusion of BODIPY-cholesterol as a function of probe structure

    DEFF Research Database (Denmark)

    Solanko, Lukasz Michal; Wüstner, Daniel; Lund, Frederik Wendelboe

    2013-01-01

    -24 of cholesterol (B-P-Chol). Using two-photon fluorescence polarimetry in giant unilamellar vesicles and in the plasma membrane (PM) of living intact and actin-disrupted cells, we show that the BODIPY-groups in B-Chol and B-P-Chol are oriented perpendicular and almost parallel to the bilayer normal......, respectively. B-Chol is in all three membrane systems much stronger oriented than B-P-Chol. Interestingly, we found that the lateral diffusion in the PM was two times slower for B-Chol than for B-P-Chol, although we found no difference in lateral diffusion in model membranes. Stimulated emission depletion...

  4. Strong influence of periodic boundary conditions on lateral diffusion in lipid bilayer membranes

    Energy Technology Data Exchange (ETDEWEB)

    Camley, Brian A. [Center for Theoretical Biological Physics and Department of Physics, University of California, San Diego, California 92093 (United States); Department of Physics, University of California, Santa Barbara, California 93106 (United States); Lerner, Michael G. [Department of Physics and Astronomy, Earlham College, Richmond, Indiana 47374 (United States); Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892 (United States); Pastor, Richard W. [Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892 (United States); Brown, Frank L. H. [Department of Physics, University of California, Santa Barbara, California 93106 (United States); Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106 (United States)

    2015-12-28

    The Saffman-Delbrück hydrodynamic model for lipid-bilayer membranes is modified to account for the periodic boundary conditions commonly imposed in molecular simulations. Predicted lateral diffusion coefficients for membrane-embedded solid bodies are sensitive to box shape and converge slowly to the limit of infinite box size, raising serious doubts for the prospects of using detailed simulations to accurately predict membrane-protein diffusivities and related transport properties. Estimates for the relative error associated with periodic boundary artifacts are 50% and higher for fully atomistic models in currently feasible simulation boxes. MARTINI simulations of LacY membrane protein diffusion and LacY dimer diffusion in DPPC membranes and lipid diffusion in pure DPPC bilayers support the underlying hydrodynamic model.

  5. Strong influence of periodic boundary conditions on lateral diffusion in lipid bilayer membranes

    Science.gov (United States)

    Camley, Brian A.; Lerner, Michael G.; Pastor, Richard W.; Brown, Frank L. H.

    2015-12-01

    The Saffman-Delbrück hydrodynamic model for lipid-bilayer membranes is modified to account for the periodic boundary conditions commonly imposed in molecular simulations. Predicted lateral diffusion coefficients for membrane-embedded solid bodies are sensitive to box shape and converge slowly to the limit of infinite box size, raising serious doubts for the prospects of using detailed simulations to accurately predict membrane-protein diffusivities and related transport properties. Estimates for the relative error associated with periodic boundary artifacts are 50% and higher for fully atomistic models in currently feasible simulation boxes. MARTINI simulations of LacY membrane protein diffusion and LacY dimer diffusion in DPPC membranes and lipid diffusion in pure DPPC bilayers support the underlying hydrodynamic model.

  6. Interplay of electron hopping and bounded diffusion during charge transport in redox polymer electrodes.

    Science.gov (United States)

    Akhoury, Abhinav; Bromberg, Lev; Hatton, T Alan

    2013-01-10

    Redox polymer electrodes (RPEs) have been prepared both by attachment of random copolymers of hydroxybutyl methacrylate and vinylferrocene (poly(HBMA-co-VF)) to carbon substrates by grafting either "to" or "from" the substrate surfaces, and by impregnation of porous carbon substrates with redox polymer gels of similar composition. An observed linear dependence of peak current on the square root of the applied voltage scan rate in cyclic voltammetry (CV) led to the conclusion that the rate controlling step in the redox process was the diffusive transfer of electrons through the redox polymer layer. The variation in the peak current with increasing concentration of the redox species in the polymer indicated that the electron transport transitioned from bounded diffusion to electron hopping. A modified form of the Blauch-Saveant equation for apparent diffusivity of electrons through a polymer film indicated that bounded diffusion was the dominant mechanism of electron transport in RPEs with un-cross-linked polymer chains at low concentrations of the redox species, but, as the concentration of the redox species increased, electron hopping became more dominant, and was the primary mode of electron diffusion above a certain concentration level of redox species. In the cross-linked polymer gels, bounded diffusion was limited because of the restricted mobility of the polymer chains. Electron hopping was the primary mode of electron diffusion in such systems at all concentrations of the redox species.

  7. Microprobe PIXE study of Ni–Ge interactions in lateral diffusion couples

    Energy Technology Data Exchange (ETDEWEB)

    Chilukusha, D. [Department of Physics, University of Zambia, P.O. Box 32379, Lusaka 10101 (Zambia); Pineda-Vargas, C.A. [iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129 (South Africa); Faculty of Health & Wellness Sciences, CPUT, Bellville (South Africa); Nemutudi, R. [iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129 (South Africa); Habanyama, A. [Department of Physics, Copperbelt University, P.O. Box 21692, Jambo Drive, Riverside, Kitwe 10101 (Zambia); Comrie, C.M. [iThemba LABS, National Research Foundation, P.O. Box 722, Somerset West 7129 (South Africa)

    2015-11-15

    Rutherford backscattering spectrometry on the nuclear microprobe (μRBS) is often used in studies of lateral diffusion couples. RBS requires that the positions of the interacting species on the periodic table are not too close in terms of atomic number and therefore do not produce excessive RBS peak overlap. In order to satisfactorily characterize systems that have atomic numbers which are close, it is necessary to find techniques which can complement μRBS. The aim of this study was to determine the extent to which particle induced X-ray emission (PIXE) could be applied in the lateral diffusion couple study of a system with relatively close atomic numbers. This was with a view that it may eventually be adopted to study systems where the atomic numbers are too close for RBS analysis. The system studied here was the Ni–Ge binary system. Since RBS is an established technique for studying lateral diffusion couples, we used it as a standard for comparison. The PIXE results showed a maximum error of 12% with reference to the RBS standard. In order to achieve the most effective use of PIXE in lateral diffusion couple studies we recommend the use of the technique in such a way as to obtain depth information and the use of relatively thick sample layers.

  8. Ultrathin MgO diffusion barriers for ferromagnetic electrodes on GaAs(001).

    Science.gov (United States)

    Sarkar, Anirban; Wang, Shibo; Grafeneder, Wolfgang; Arndt, Martin; Koch, Reinhold

    2015-04-24

    Ultrathin MgO(100) films serving as a diffusion barrier between ferromagnetic electrodes and GaAs(001) semiconductor templates have been investigated. Using Fe as an exemplary ferromagnetic material, heterostructures of Fe/MgO/GaAs(001) were prepared at 200 °C with the MgO thickness ranging from 1.5 to 3 nm. Structural characterization reveals very good crystalline ordering in all layers of the heterostructure. Auger electron spectroscopy depth-profiling and cross-sectional high-resolution transmission electron microscopy evidence diffusion of Fe into MgO and-for too thin MgO barriers-further into GaAs(001). Our results recommend a MgO barrier thickness larger than or equal to 2.6 nm for its application as a reliable diffusion barrier on GaAs(001) in spintronics devices.

  9. Comparative study on electrochemical degradation of 4-chlorophenol by different Pd/C gas diffusion electrodes

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Pd/C catalyst used for the Pd/C gas diffusion cathodes was prepared by hydrogen reduction method and formaldehyde reduction method, and characterized by X-ray diffraction (XRD), transmission electrode microcopy (TEM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV) techniques. The electrochemical degradation of 4-chlorophenol was investigated in the diaphragm electrolysis system, aerating firstly with hydrogen gas then with air, using three different kinds of gas diffusion cathode. The results indicated that the self-made Pd/C gas diffusion cathode can not only reductively dechlorinate 4-chlorophenols by aerating hydrogen gas, but also accelerate the two-electron reduction of O2 to hydrogen peroxide (H2O2) by aerating air. Therefore, the removal efficiency of 4-chlorophenol by using Pd/C gas diffusion cathode is better than that of the C/PTFE gas diffusion cathode (no catalyst). The catalytic activity of Pd/C catalyst prepared by hydrogen reduction method is higher than that prepared by formaldehyde reduction method. The stability of the Pd/C gas diffusion cathodes is good. Therefore, both the removal efficiency and the dechlorination degree of 4-chlorophenol reached about 100% after 60 min, and the removal efficiency of 4-chlorophenol in terms of chemical oxygen demand (COD) in the cathodic compartment reached 87.4% after 120 min.

  10. Energetics of lateral eddy diffusion/advection:Part IV. Energetics of diffusion/advection in sigma coordinates and other coordinates

    Institute of Scientific and Technical Information of China (English)

    HUANG Rui Xin

    2014-01-01

    Gravitational potential energy (GPE) source and sink due to stirring and cabbeling associated with sigma dif-fusion/advection is analyzed. It is shown that GPE source and sink is too big, and they are not closely linked to physical property distribution, such as temperature, salinity and velocity. Although the most frequently quoted advantage of sigma coordinate models are their capability of dealing with topography;the exces-sive amount of GPE source and sink due to stirring and cabbeling associated with sigma diffusion/advec-tion diagnosed from our analysis raises a very serious question whether the way lateral diffusion/advection simulated in the sigma coordinates model is physically acceptable. GPE source and sink in three coordinates is dramatically different in their magnitude and patterns. Overall, in terms of simulating lateral eddy diffu-sion and advection isopycnal coordinates is the best choice and sigma coordinates is the worst. The physical reason of the excessive GPE source and sink in sigma coordinates is further explored in details. However, even in the isopycnal coordinates, simulation based on the Eulerian coordinates can be contaminated by the numerical errors associated with the advection terms.

  11. LaNiO3-based catalyst in gas diffusion electrodes: activity and stability for oxigen reactions

    OpenAIRE

    R.A. Silva; Soares, C. O.; CARVALHO, M. D. de; Jorge, M. E. Melo; Gomes, A.; C. M. Rangel; Pereira, M. I. da Silva

    2013-01-01

    Perovskite-type oxides are potential catalysts for next generation of regenerative fuel cells. In particular, LaNiO3 has been recognised as one of the most promising oxygen electrodes. In this work LaNiO3 perovskite-type oxides, prepared by a self-combustion method [1, 2], have been used for the preparation of porous gas-diffusion electrodes (GDE). Electrodes were prepared on Toray carbon paper (CP) substrates, consisting of a diffusion layer, a catalyst layer and a Nafion® layer. The gas...

  12. Forward modeling and inversion of responses for borehole normal and lateral electrode arrangements

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J.H.

    1986-01-01

    The finite difference method is used to solve the forward problems which simulate the borehole normal and lateral electrode arrangements for the combined boundary (2-D) earth model which has both horizontal and cylindrical boundaries. The ridge regression estimator is then applied to solve the inverse problems which determine the earth parameters such as bed boundaries, extent of invaded zones, and vertical and horizontal resistivity profiles from the borehole normal and lateral resistivity logs. The apparent resistivity values in the presence of borehole mud, invaded zone, and horizontal bed boundaries can be obtained from an earth geometry provided that the model is symmetric around the borehole axis. The quick and accurate forward calculations are achieved by using a gradually expanding grid system and a terminal resistance type boundary condition, and by using a two-dimensional average resistivity scheme in a grid block. The finite difference solutions are verified against analytical solutions for limiting cases, and excellent agreement in obtained. The finite difference forward modeling also can be used for investigation into the effects of the earth parameter variations on the apparent resistivities. Inverse modeling is tested on synthetic and field data. The field data are inverted to a horizontally layered (1-D) model, and the theoretical data are inverted to a 2-D model. The test results indicate that the thickness and the resistivity of each layer can be determined simultaneously. For the practical inversion of field data, the 1-D model inversion results can be used as a first try model of the 2-d inversion. Interactive inverse modeling can be used for an automatic interpretation of the resistivity logs, with models constrained by logging and geologic information.

  13. Effect of curcumin on lateral diffusion of phosphatidylcholines in saturated and unsaturated bilayers.

    Science.gov (United States)

    Filippov, Andrei V; Kotenkov, Sergey A; Munavirov, Bulat; Antzutkin, Oleg N

    2014-09-01

    Curcumin, a dietary polyphenol, is a natural spice with preventive and therapeutic potential for neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Curcumin possesses a spectrum of antioxidant, anti-inflammatory, anticarcinogenic, and antimutagenic properties. Because of this broad spectrum of pharmacological activity, it has been suggested that, like cholesterol, curcumin exerts its effect on a rather basic biological level, such as on lipid bilayers of biomembranes. The effect of curcumin on translational mobility of lipids in biomembranes has not yet been studied. In this work, we used (1)H NMR diffusometry to explore lateral diffusion in planar-oriented bilayers of dimyristoylphosphatidylcholine (DMPC) and dioleoylphosphatidylcholine (DOPC) at curcumin concentrations of up to 40 mol % and in the temperature range of 298-333 K. The presence of curcumin at much lower concentrations (∼7 mol %) leads to a decrease in the lateral diffusion coefficient of DOPC by a factor of 1.3 at lower temperatures and by a factor of 1.14 at higher temperatures. For DMPC, the diffusion coefficient decreases by a factor of 1.5 at lower temperatures and by a factor of 1.2 at higher temperatures. Further increasing the curcumin concentration has no effect. Comparison with cholesterol showed that curcumin and cholesterol influence lateral diffusion of lipids differently. The effect of curcumin is determined by its solubility in lipid bilayers, which is as low as 10 mol % that is much less than that of cholesteroĺs 66 mol %.

  14. Spin diffusion length of Permalloy using spin absorption in lateral spin valves

    Science.gov (United States)

    Sagasta, Edurne; Omori, Yasutomo; Isasa, Miren; Otani, YoshiChika; Hueso, Luis E.; Casanova, Fèlix

    2017-08-01

    We employ the spin absorption technique in lateral spin valves to extract the spin diffusion length of Permalloy (Py) as a function of temperature and resistivity. A linear dependence of the spin diffusion length with the conductivity of Py is observed, evidencing that the Elliott-Yafet mechanism is the dominant spin relaxation mechanism in Permalloy. Completing the dataset with additional data found in the literature, we obtain λPy = (0.91 ± 0.04) (fΩm2)/ρPy.

  15. Strong dependency of lithium diffusion on mechanical constraints in high-capacity Li-ion battery electrodes

    Institute of Scientific and Technical Information of China (English)

    Yi-Fan Gao; Min Zhou

    2012-01-01

    The effect of external constraints on Li diffusion in high-capacity Li-ion battery electrodes is investigated using a coupled finite deformation theory.It is found that thinfilm electrodes on rigid substrates experience much slower diffusion rates compared with free-standing films with the same material properties and geometric dimensions.More importantly,the study reveals that mechanical driving forces tend to retard diffusion in highly-constrained thin films when lithiation-induced softening is considered,in contrast to the fact that mechanical driving forces always enhance diffusion when deformation is fully elastic.The results provide further proof that nano-particles are a better design option for nextgeneration alloy-based electrodes compared with thin films.

  16. A large-scale multicentre cerebral diffusion tensor imaging study in amyotrophic lateral sclerosis

    OpenAIRE

    Muller, Hans-Peter; R Turner, Martin; Grosskreutz, Julian; Abrahams, Sharon; Bede, Peter; Govind, Varan; Prudlo, Johannes; Ludolph, Albert C.; Filippi, Massimo; Kassubek, Jan

    2016-01-01

    Objective: Damage to the cerebral tissue structural connectivity associated with amyotrophic lateral sclerosis (ALS), which extends beyond the motor pathways, can be visualized by diffusion tensor imaging (DTI). The effective translation of DTI metrics as biomarker requires its application across multiple magnetic resonance imaging scanners and patient cohorts. A multi-centre study was undertaken to assess structural connectivity in ALS at a large sample size. Methods: Four-hundred-and-forty-...

  17. Diffusion tensor tract-specific analysis of the uncinate fasciculus in patients with amyotrophic lateral sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Kanako; Masutani, Yoshitaka; Watadani, Takeyuki; Nakata, Yasuhiro; Yoshida, Mariko; Abe, Osamu; Ohtomo, Kuni [University of Tokyo, Department of Radiology, Graduate School of Medicine, Bunkyo, Tokyo (Japan); Aoki, Shigeki [Juntendo University, Department of Radiology, Bunkyo, Tokyo (Japan); Iwata, Nobue K.; Terao, Yasuo; Tsuji, Shoji [University of Tokyo, Department of Neurology, Graduate School of Medicine, Bunkyo, Tokyo (Japan)

    2010-08-15

    The uncinate fasciculus (UF) consists of core fibers connecting the frontal and temporal lobes and is considered to be related to cognitive/behavioral function. Using diffusion tensor tractography, we quantitatively evaluated changes in fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) of the UF by tract-specific analysis to evaluate the damage of the UF in patients with amyotrophic lateral sclerosis (ALS). We obtained diffusion tensor images of 15 patients with ALS and 9 age-matched volunteers. Patients with ALS showed significantly lower mean FA (P = 0.029) compared with controls. No significant difference was seen in mean ADC. The results suggest that damage of the UF in patients with ALS can be quantitatively evaluated with FA. (orig.)

  18. Amperometric Determination of Sulfite by Gas Diffusion- Sequential Injection with Boron-Doped Diamond Electrode

    Directory of Open Access Journals (Sweden)

    Orawon Chailapakul

    2008-03-01

    Full Text Available A gas diffusion sequential injection system with amperometric detection using aboron-doped diamond electrode was developed for the determination of sulfite. A gasdiffusion unit (GDU was used to prevent interference from sample matrices for theelectrochemical measurement. The sample was mixed with an acid solution to generategaseous sulfur dioxide prior to its passage through the donor channel of the GDU. Thesulfur dioxide diffused through the PTFE hydrophobic membrane into a carrier solution of 0.1 M phosphate buffer (pH 8/0.1% sodium dodecyl sulfate in the acceptor channel of theGDU and turned to sulfite. Then the sulfite was carried to the electrochemical flow cell anddetected directly by amperometry using the boron-doped diamond electrode at 0.95 V(versus Ag/AgCl. Sodium dodecyl sulfate was added to the carrier solution to preventelectrode fouling. This method was applicable in the concentration range of 0.2-20 mgSO32−/L and a detection limit (S/N = 3 of 0.05 mg SO32−/L was achieved. This method wassuccessfully applied to the determination of sulfite in wines and the analytical resultsagreed well with those obtained by iodimetric titration. The relative standard deviations forthe analysis of sulfite in wines were in the range of 1.0-4.1 %. The sampling frequency was65 h−1.

  19. Killing of total heterotrophic bacteria using the gas diffusion electrode system.

    Science.gov (United States)

    Xu, W Y; Li, P

    2012-06-01

    This study focused on the disinfection of dual electrodes with a gas diffusion cathode using total heterotrophic bacteria as indicator microorganisms. Batch tests were performed to study the effects of platinum load W(Pt) and the pore-forming agent content WNH4HCO3 in gas diffusion electrodes on the germicidal efficacy eta and H2O2 yield. The results showed that the disinfection improved with W(Pt), but its efficiency at W(Pt) of 3 per thousand was equivalent to W(Pt) of 4 per thousand. The right amount of the pore-forming agent improved disinfection. Continuous tests were performed to study residence times (RTs), pH and oxygen flow rates Qo2 on the germicidal efficacy and H2O2 yield. The results indicated that at the steady state total heterotrophic bacteria in the outlet stream were completely inactivated under our experimental conditions. Disinfection improved with increasing RT. This phenomenon was more significant when RT disinfection shortened with an increasing oxygen flow rate Qo2. The operating costs are high. Further research is required to fully understand all parameters and reduce operating costs.

  20. Lateral-crack-free, buckled, inkjet-printed silver electrodes on highly pre-stretched elastomeric substrates

    Science.gov (United States)

    Lee, Jaemyon; Chung, Seungjun; Song, Hyunsoo; Kim, Sangwoo; Hong, Yongtaek

    2013-03-01

    We report the formation of lateral-crack-free silver electrodes on highly pre-stretched poly(dimethylsiloxane) (PDMS) substrates using the inkjet-printing method followed by an annealing process under the pre-stretched state. Due to Poisson's effect, cracks are easily obtained in the direction lateral to the pre-stretching and releasing directions when the highly pre-stretched substrate is released after the electrode formation. In our method, however, Poisson's effect is suppressed significantly from the PDMS thermal expansion perpendicular to the pre-stretched direction during the annealing process. In order to prevent the formation of a lateral crack, the annealing temperature needs to be optimized for each pre-stretching condition. We modelled their relationship using Poisson's ratios and thermal expansion coefficients of the substrate and silver materials. Our measurement results showed consistent result with the simulation. The resistance of the fabricated silver electrodes negligibly changes under up to 17% strain and even after 1000 time stretching cycle tests.

  1. Lateral diffusion of membrane proteins: consequences of hydrophobic mismatch and lipid composition.

    Science.gov (United States)

    Ramadurai, Sivaramakrishnan; Duurkens, Ria; Krasnikov, Victor V; Poolman, Bert

    2010-09-08

    Biological membranes are composed of a large number lipid species differing in hydrophobic length, degree of saturation, and charge and size of the headgroup. We now present data on the effect of hydrocarbon chain length of the lipids and headgroup composition on the lateral mobility of the proteins in model membranes. The trimeric glutamate transporter (GltT) and the monomeric lactose transporter (LacY) were reconstituted in giant unilamellar vesicles composed of unsaturated phosphocholine lipids of varying acyl chain length (14-22 carbon atoms) and various ratios of DOPE/DOPG/DOPC lipids. The lateral mobility of the proteins and of a fluorescent lipid analog was determined as a function of the hydrophobic thickness of the bilayer (h) and lipid composition, using fluorescence correlation spectroscopy. The diffusion coefficient of LacY decreased with increasing thickness of the bilayer, in accordance with the continuum hydrodynamic model of Saffman-Delbrück. For GltT, the mobility had its maximum at diC18:1 PC, which is close to the hydrophobic thickness of the bilayer in vivo. The lateral mobility decreased linearly with the concentration of DOPE but was not affected by the fraction of anionic lipids from DOPG. The addition of DOPG and DOPE did not affect the activity of GltT. We conclude that the hydrophobic thickness of the bilayer is a major determinant of molecule diffusion in membranes, but protein-specific properties may lead to deviations from the Saffman-Delbrück model.

  2. CAD/CAM-designed 3D-printed electroanalytical cell for the evaluation of nanostructured gas-diffusion electrodes

    Science.gov (United States)

    Chervin, Christopher N.; Parker, Joseph F.; Nelson, Eric S.; Rolison, Debra R.; Long, Jeffrey W.

    2016-04-01

    The ability to effectively screen and validate gas-diffusion electrodes is critical to the development of next-generation metal-air batteries and regenerative fuel cells. The limiting electrode in a classic two-terminal device such as a battery or fuel cell is difficult to discern without an internal reference electrode, but the flooded electrolyte characteristic of three-electrode electroanalytical cells negates the prime function of an air electrode—a void volume freely accessible to gases. The nanostructured catalysts that drive the energy-conversion reactions (e.g., oxygen reduction and evolution in the air electrode of metal-air batteries) are best evaluated in the electrode structure as-used in the practical device. We have designed, 3D-printed, and characterized an air-breathing, thermodynamically referenced electroanalytical cell that allows us to mimic the Janus arrangement of the gas-diffusion electrode in a metal-air cell: one face freely exposed to gases, the other wetted by electrolyte.

  3. MRI of paraventricular white matter lesions in amyotrophic lateral sclerosis. Analysis by diffusion-weighted images

    Energy Technology Data Exchange (ETDEWEB)

    Segawa, Fuminori; Kinoshita, Masao (Toho Univ., Tokyo (Japan). Ohashi Hospital); Kishibayashi, Jun; Kamada, Kazuhiko; Sunohara, Nobuhiko

    1994-09-01

    Magnetic resonance images in some cases of amyotrophic lateral sclerosis (ALS) revealed abnormal signals in both the paraventriculer white matter and in the posterior limbs of the internal capsule. We examined T[sub 2]- and diffusion-weighted MR images of these lesions in 18 cases of ALS. There were symmetrical high-signal areas in the posterior limbs of the internal capsule in all of the cases. The high-signal areas in the internal capsule corresponded to the pyramidal tracts in the anatomical atlas by Talairach. In 5 of the cases of ALS, T[sub 2]-weighted MR images showed discrete paraventricular white matter lesions as well. The mean age of the ALS patients with paraventricular white matter lesions was higher than that of the ALS patients without such lesions. Proton densities calculated from the conventional MR images were higher in both the capsular and paraventricular lesions. The diffusion coefficients perpendicular to the pyramidal tract in the internal capsular lesions were within the normal range, where as the diffusion coefficients in the paraventricular lesions were increased in all directions. Thus, diffusion anisotropy was lost in the paraventricular lesions. These findings are similar to those observed in the white matter lesions of cerebro-vascular origin. As a result, the pathology of the paraventricular lesions in ALS was confirmed to be different from that of the internal capsular lesions. (author).

  4. Lateral charge carrier diffusion in InGaN quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Danhof, J.; Solowan, H.M.; Schwarz, U.T. [Albert-Ludwigs-Universitaet Freiburg, IMTEK, Georges-Koehler-Allee 106, 79110 Freiburg (Germany); Fraunhofer Institute for Applied Solid State Physics IAF, Tullastrasse 72, 79108 Freiburg (Germany); Kaneta, A.; Kawakami, Y. [Kyoto University, Katsura Campus, Nishikyo-ku, Kyoto 615-2312 (Japan); Schiavon, D.; Meyer, T.; Peter, M. [Osram Opto Semiconductors GmbH, Leibnizstrasse 4, 93055 Regensburg (Germany)

    2012-03-15

    We investigated lateral charge carrier transport in indium gallium nitride InGaN/GaN multi-quantum wells for two different samples, one sample emitting green light at about 510 nm and the other emitting cyan light at about 470 nm. For the cyan light emitting sample we found a diffusion constant of 1.2 cm{sup 2}/s and for the green light emitting sample 0.25 cm{sup 2}/s. The large difference in diffusion constant is due to a higher point defect density in the green light emitting quantum wells (QWs) as high indium incorporation tends to reduce material quality. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Silica-waveguide thermooptic phase shifter with low power consumption and low lateral heat diffusion

    DEFF Research Database (Denmark)

    Andersen, Bo Asp Møller; Jensen, Lars; Laurent-Lund, Christian

    1993-01-01

    A thermooptic (TO) phase shifter consisting of a thin film heater on the top of a loaded stripline silica waveguide on a silicon substrate is shown to exhibit faster time response than reported for phase shifters based on a buried silica waveguide configuration. The risetime was measured to be 0.......24 ms, which is in good agreement with calculated thermal distributions in the structures. The lateral heat diffusion distance in the loaded stripline structure is shown to be smaller than in buried waveguide structures. This implies small thermal crosstalk and suggests a high-level integration...

  6. Electro-scrubbing volatile organic carbons in the air stream with a gas diffusion electrode

    Energy Technology Data Exchange (ETDEWEB)

    Yang Ji, E-mail: yangji@ecust.edu.cn [School of Resources and Environmental Engineering, State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, East China University of Science and Technology, Shanghai 200237 (China); School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu Kaichen; Jia Jinping; Cao Limei [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2011-04-15

    It is demonstrated that exposing the VOC air streams to the electro-scrubbing reactor with a gas diffusion electrode leads to an efficient removal of organics. The importance order of the influence factors on the electro-scrubbing reactor performance is: conductivity, voltage and air stream flow-rate. The effective conductivity and high voltages generally are beneficial to the removal process and the air flow-rate is not a significant factor compared with the other two, indicating that the reactor might have a consistently satisfying performance within a wide range of gas volumetric load. The mass transfer of both organics and oxygen in the reactor is estimated by mathematical model, and the calculation determines the concentration boundary conditions for the 2-ethoxyethyl acetate removal: if the 2-ethoxyethyl acetate concentration in the inflow air stream holds C{sub G,i} {<=} 0.7198 % , the removal in the electro-scrubbing reactor is electrochemical reaction controlled; if C{sub G,i} > 0.7198 % , the controlling step will be the oxygen mass transfer from the air to the liquid in the electro-scrubbing reactor. The Apparent Current Efficiency of the electro-scrubbing reactor was also determined using COD data, which is significantly higher than some commercial metal oxide electrodes, showing that the reactor is energy efficient and has the promise for the future scale-up.

  7. Determination of corrosion rate of reinforcement with a modulated guard ring electrode; analysis of errors due to lateral current distribution

    Energy Technology Data Exchange (ETDEWEB)

    Wojtas, H

    2004-07-01

    The main source of errors in measuring the corrosion rate of rebars on site is a non-uniform current distribution between the small counter electrode (CE) on the concrete surface and the large rebar network. Guard ring electrodes (GEs) are used in an attempt to confine the excitation current within a defined area. In order to better understand the functioning of modulated guard ring electrode and to assess its effectiveness in eliminating errors due to lateral spread of current signal from the small CE, measurements of the polarisation resistance performed on a concrete beam have been numerically simulated. Effect of parameters such as rebar corrosion activity, concrete resistivity, concrete cover depth and size of the corroding area on errors in the estimation of polarisation resistance of a single rebar has been examined. The results indicate that modulated GE arrangement fails to confine the lateral spread of the CE current within a constant area. Using the constant diameter of confinement for the calculation of corrosion rate may lead to serious errors when test conditions change. When high corrosion activity of rebar and/or local corrosion occur, the use of the modulated GE confinement may lead to significant underestimation of the corrosion rate.

  8. Lateral diffusion of PEG-Lipid in magnetically aligned bicelles measured using stimulated echo pulsed field gradient 1H NMR.

    Science.gov (United States)

    Soong, Ronald; Macdonald, Peter M

    2005-01-01

    Lateral diffusion measurements of PEG-lipid incorporated into magnetically aligned bicelles are demonstrated using stimulated echo (STE) pulsed field gradient (PFG) proton (1H) nuclear magnetic resonance (NMR) spectroscopy. Bicelles were composed of dimyristoyl phosphatidylcholine (DMPC) plus dihexanoyl phosphatidylcholine (DHPC) (q = DMPC/DHPC molar ratio = 4.5) plus 1 mol % (relative to DMPC) dimyristoyl phosphatidylethanolamine-N-[methoxy(polyethylene glycol)-2000] (DMPE-PEG 2000) at 25 wt % lipid. 1H NMR STE spectra of perpendicular aligned bicelles contained only resonances assigned to residual HDO and to overlapping contributions from a DMPE-PEG 2000 ethoxy headgroup plus DHPC choline methyl protons. Decay of the latter's STE intensity in the STE PFG 1H NMR experiment (g(z) = 244 G cm(-1)) yielded a DMPE-PEG 2000 (1 mol %, 35 degrees C) lateral diffusion coefficient D = 1.35 x 10(-11) m2 s(-1). Hence, below the "mushroom-to-brush" transition, DMPE-PEG 2000 lateral diffusion is dictated by its DMPE hydrophobic anchor. D was independent of the diffusion time, indicating unrestricted lateral diffusion over root mean-square diffusion distances of microns, supporting the "perforated lamellae" model of bicelle structure under these conditions. Overall, the results demonstrate the feasibility of lateral diffusion measurements in magnetically aligned bicelles using the STE PFG NMR technique.

  9. Laterally configured resistive switching device based on transition-metal nano-gap electrode on Gd oxide

    Energy Technology Data Exchange (ETDEWEB)

    Kawakita, Masatoshi; Okabe, Kyota [Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan); Kimura, Takashi [Department of Physics, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan); Research Center for Quantum Nano-Spin Sciences, Kyushu University, 6-10-1 Hakozaki, Fukuoka 812-8581 (Japan)

    2016-01-11

    We have developed a fabrication process for a laterally configured resistive switching device based on a Gd oxide. A nano-gap electrode connected by a Gd oxide with the ideal interfaces has been created by adapting the electro-migration method in a metal/GdO{sub x} bilayer system. Bipolar set and reset operations have been clearly observed in the Pt/GdO{sub x} system similarly in the vertical device based on GdO{sub x}. Interestingly, we were able to observe a clear bipolar switching also in a ferromagnetic CoFeB nano-gap electrode with better stability compared to the Pt/GdO{sub x} device. The superior performance of the CoFeB/GdO{sub x} device implies the importance of the spin on the resistive switching.

  10. A Study of Gas Diffusion Electrodes for the Coupled Reaction of Water Electrolysis and Electrocatalytic Benzene Hydrogenation

    Institute of Scientific and Technical Information of China (English)

    HuangHaiyan; YuYing; WangJing

    2005-01-01

    Gas diffusion electrodes are applied to the coupled reaction of water electrolysis and electrocatalytic benzene hydrogenation. The effects of the preparation conditions of electrodes, electrolyte acidity, the concentration of benzene and water vapor, and the flow rate of N2 are investigated by evaluating the efficiency of the current. Furthermore, the optimal operational conditions have been ascertained. The results of our experiment show that gas diffusion electrodes have good performance when the content of PTFE is 10% (wt) and that of Nation is 0.75mg/cm2. The optimal operational conditions are as follows: The temperature of electrolysis is 70℃, acidity 0.5tool/L, the concentration of benzene 26%,the concentration of vapor 10%, the flow rate of N2 80mL/min-240mL/min. The efficiency of the current can reach 35% under optimal operational conditions. Then, a conclusion can be drawn that gas diffusion electrodes can improve the rate of the coupled reaction effectively.

  11. Effect of local velocity on diffusion-induced stress in large-deformation electrodes of lithium-ion batteries

    Science.gov (United States)

    Li, Yong; Zhang, Kai; Zheng, Bailin; Yang, Fuqian

    2016-07-01

    In this work, the contribution of local velocity to the resultant flux of lithium in lithium-ion battery is introduced into the diffusion equation to describe the migration of lithium in the active material of electrodes. The effect of the local velocity on the stress evolution in a spherical electrode made of silicon is analyzed, using the derived diffusion equation and nonlinear theory of elasticity. Two boundary conditions at the surface of the electrode, which represent two extreme conditions of real electrode materials, are used in the stress analysis: one is stress-free, and the other is immobile. The numerical results with the stress-free boundary condition suggest that the effect of the local velocity on the distribution of radial stress and hoop stress increases with the increase of time and the effect of the local velocity on the distribution of lithium is relatively small. In comparison with the results without the effect of the local velocity, the effect of the local velocity is negligible for the immobile boundary condition. The numerical result shows that the use of the immobile boundary condition leads to the decrease of von-Mises stress, which likely will retard the mechanical degradation of electrode and improve the electrochemical performance of lithium-ion battery.

  12. New Power Lateral Double Diffused Metal-Oxide-Semiconductor Transistor with a Folded Accumulation Layer

    Institute of Scientific and Technical Information of China (English)

    DUAN Bao-Xing; ZHANG Bo; LI Zhao-Ji

    2007-01-01

    A new lateral double diffused metal oxide semiconductor field effect transistor with a double-charge accumulation layer using a folded silicon substrate is proposed to improve the performance of the breakdown voltage and specific on-resistance. Three kinds of technologies, which are the additional electric field modulation effect, majority carrier accumulation and increasing the effective conduction area, are applied simultaneously by a semi-insulating polycrystalline silicon layer deposited over the top of thin oxide covering the drift region. It is indicated that by the simulator, the ideal silicon limits of the breakdown voltage and specific on-resistance have been broken due to the complete three-dimensional reduced surface field effect and the doubled majority carrier accumulation layer.

  13. Nano-fabricated perpendicular magnetic anisotropy electrodes for lateral spin valves and observation of Nernst-Ettingshausen related signals

    Energy Technology Data Exchange (ETDEWEB)

    Chejanovsky, N.; Sharoni, A., E-mail: amos.sharoni@biu.ac.il [Department of Physics and Institute of Nanotechnology and Advanced Materials, Bar Ilan University, Ramat-Gan 590002 (Israel)

    2014-08-21

    Lateral spin valves (LSVs) are efficient structures for characterizing spin currents in spintronics devices. Most LSVs are based on ferromagnetic (FM) electrodes for spin-injection and detection. While there are advantages for using perpendicular magnetic anisotropy (PMA) FM, e.g., stability to nano-scaling, these have almost not been studied. This is mainly due to difficulties in fabricating PMA FMs in a lateral geometry. We present here an efficient method, based on ion-milling through an AlN mask, for fabrication of LSVs with multi-layered PMA FMs such as Co/Pd and Co/Ni. We demonstrate, using standard permalloy FMs, that the method enables efficient spin injection. We show the multi-layer electrodes retain their PMA properties as well as spin injection and detection in PMA LSVs. In addition, we find a large asymmetric voltage signal which increases with current. We attribute this to a Nernst-Ettingshausen effect caused by local Joule heating and the perpendicular magnetic easy axis.

  14. Lateral diffusion of phospholipids in the plasma membrane of soybean protoplasts: Evidence for membrane lipid domains.

    Science.gov (United States)

    Metcalf, T N; Wang, J L; Schindler, M

    1986-01-01

    Fluorescent lipid and phospholipid probes were incorporated at 4 degrees C into soybean protoplasts prepared from cultured soybean (SB-1) cells. Fluorescence microscopy showed that the plasma membrane as well as the nucleus were labeled. Fluorescence redistribution after photobleaching (FRAP) analysis was performed on these cells at 18 degrees C to monitor the lateral mobility of the incorporated probes. After labeling at low concentrations (40 mug/ml) of phosphatidyl-N-(4-nitrobenzo-2-oxa-1,3-diazolyl)ethanolamine (NBD-PtdEtn), a single mobile component was observed with a diffusion coefficient (D) of approximately 3 x 10(-9) cm(2)/sec. After labeling at higher probe concentrations (>/=100 mug/ml), two diffusing species were observed, with diffusion coefficients of approximately 3 x 10(-9) cm(2)/sec ("fast") and approximately 5 x 10(-10) cm(2)/sec ("slow"). Similar results were observed with fluorescent derivatives of phosphatidylcholine and fatty acids. In contrast to these results, parallel analysis of 3T3 fibroblasts, using the same probes and conditions, yielded only a single diffusion component. These results suggest that the soybean plasma membrane may contain two distinct lipid domains in terms of lipid mobility. Consistent with this idea, experiments with soybean protoplasts yielded a single diffusion component under the following conditions: (i) labeling with NBD-PtdEtn (100 mug/ml), FRAP analysis at 37 degrees C (D = 1.1 x 10(-8) cm(2)/sec); (ii) labeling with NBD-PtdEtn (100 mug/ml), FRAP analysis at 18 degrees C in the presence of 2 mM EGTA (D = 4.2 x 10(-9) cm(2)/sec); (iii) labeling with 5-(N-dodecanoyl)aminofluorescein (a short-chain lipid probe), FRAP analysis at 18 degrees C or 37 degrees C (D = 2.5 x 10(-8) cm(2)/sec). These results suggest that the plasma membrane of soybean cells may contain stable immiscible domains of fluid and gel-like lipids.

  15. Structural and diffusion imaging versus clinical assessment to monitor amyotrophic lateral sclerosis

    Science.gov (United States)

    Cardenas-Blanco, Arturo; Machts, Judith; Acosta-Cabronero, Julio; Kaufmann, Joern; Abdulla, Susanne; Kollewe, Katja; Petri, Susanne; Schreiber, Stefanie; Heinze, Hans-Jochen; Dengler, Reinhard; Vielhaber, Stefan; Nestor, Peter J.

    2016-01-01

    Amyotrophic lateral sclerosis is a progressive neurodegenerative disease that affects upper and lower motor neurons. Observational and intervention studies can be tracked using clinical measures such as the revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R) but for a complete understanding of disease progression, objective in vivo biomarkers of both central and peripheral motor pathway pathology are highly desirable. The aim of this study was to determine the utility of structural and diffusion imaging as central nervous system biomarkers compared to the standard clinical measure, ALSFRS-R, to track longitudinal evolution using three time-point measurements. N = 34 patients with ALS were scanned and clinically assessed three times at a mean of three month time intervals. The MRI biomarkers were structural T1-weighted volumes for cortical thickness measurement as well as deep grey matter volumetry, voxel-based morphometry and diffusion tensor imaging (DTI). Cortical thickness focused specifically on the precentral gyrus while quantitative DTI biomarkers focused on the corticospinal tracts. The evolution of imaging biomarkers and ALSFRS-R scores over time were analysed using a mixed effects model that accounted for the scanning interval as a fixed effect variable, and, the initial measurements and time from onset as random variables. The mixed effects model showed a significant decrease in the ALSFRS-R score, (p  0.5). In addition, deep grey matter volumetry and voxel-based morphometry also identified no significant changes. Furthermore, the availability of three time points was able to indicate that there was a linear progression in both clinical and fractional anisotropy measures adding to the validity of these results. The results indicate that DTI is clearly a superior imaging marker compared to atrophy for tracking the evolution of the disease and can act as a central nervous biomarker in longitudinal studies. It remains, however, less

  16. Structural and diffusion imaging versus clinical assessment to monitor amyotrophic lateral sclerosis

    Directory of Open Access Journals (Sweden)

    Arturo Cardenas-Blanco

    2016-01-01

    Full Text Available Amyotrophic lateral sclerosis is a progressive neurodegenerative disease that affects upper and lower motor neurons. Observational and intervention studies can be tracked using clinical measures such as the revised Amyotrophic Lateral Sclerosis Functional Rating Scale (ALSFRS-R but for a complete understanding of disease progression, objective in vivo biomarkers of both central and peripheral motor pathway pathology are highly desirable. The aim of this study was to determine the utility of structural and diffusion imaging as central nervous system biomarkers compared to the standard clinical measure, ALSFRS-R, to track longitudinal evolution using three time-point measurements. N = 34 patients with ALS were scanned and clinically assessed three times at a mean of three month time intervals. The MRI biomarkers were structural T1-weighted volumes for cortical thickness measurement as well as deep grey matter volumetry, voxel-based morphometry and diffusion tensor imaging (DTI. Cortical thickness focused specifically on the precentral gyrus while quantitative DTI biomarkers focused on the corticospinal tracts. The evolution of imaging biomarkers and ALSFRS-R scores over time were analysed using a mixed effects model that accounted for the scanning interval as a fixed effect variable, and, the initial measurements and time from onset as random variables. The mixed effects model showed a significant decrease in the ALSFRS-R score, (p  0.5. In addition, deep grey matter volumetry and voxel-based morphometry also identified no significant changes. Furthermore, the availability of three time points was able to indicate that there was a linear progression in both clinical and fractional anisotropy measures adding to the validity of these results. The results indicate that DTI is clearly a superior imaging marker compared to atrophy for tracking the evolution of the disease and can act as a central nervous biomarker in longitudinal studies. It

  17. Lateral diffusion and signaling of receptor for advanced glycation end-products (RAGE): a receptor involved in chronic inflammation.

    Science.gov (United States)

    Syed, Aleem; Zhu, Qiaochu; Smith, Emily A

    2017-06-16

    Membrane diffusion is one of the key mechanisms in the cellular function of receptors. The signaling of receptors for advanced glycation end-products (RAGE) has been extensively studied in the context of several pathological conditions, however, very little is known about RAGE diffusion. To fill this gap, RAGE lateral diffusion is probed in native, cholesterol-depleted, and cytoskeleton-altered cellular conditions. In native GM07373 cellular conditions, RAGE has a 90% mobile fraction and an average diffusion coefficient of 0.3 μm(2)/s. When depolymerization of the actin cytoskeleton is inhibited with the small molecule jasplakinolide (Jsp), the RAGE mobile fraction and diffusion coefficient decrease by 22 and 37%, respectively. In contrast, depolymerizing the filamentous actin cytoskeleton using the small molecule cytochalasin D (CD) does not alter the RAGE diffusion properties. There is a 70 and 50% decrease in phosphorylation of extracellular signal-regulated kinase (p-ERK) when the actin cytoskeleton is disrupted by CD or Jsp, respectively, in RAGE-expressing GM07373 cells. Disrupting the actin cytoskeleton in GM07373 cells that do not express detectable amounts of RAGE results in no change in p-ERK. Cholesterol depletion results in no statistically significant change in the diffusion properties of RAGE or p-ERK. This work presents a strong link between the actin cytoskeleton and RAGE diffusion and downstream signaling, and serves to further our understanding of the factors influencing RAGE lateral diffusion.

  18. Gradation of mechanical properties in gas-diffusion electrode. Part 2: Heterogeneous carbon fiber and damage evolution in cell layers

    Science.gov (United States)

    Poornesh, K. K.; Cho, C. D.; Lee, G. B.; Tak, Y. S.

    In PEM fuel cell, gas-diffusion electrode (GDE) plays very significant role in force transmission from bipolar plate to the membrane. This paper investigates the effects of geometrical heterogeneities of gas-diffusion electrode layer (gas-diffusion layer (GDL) and catalyst layer (CL)) on mechanical damage evolution and propagation. We present a structural integrity principle of membrane electrode assembly (MEA) based on the interlayer stress transfer capacity and corresponding cell layer material response. Commonly observable damages such as rupture of hydrophobic coating and breakage of carbon fiber in gas-diffusion layer are attributed to the ductile to brittle phase transition within a single carbon fiber. Effect of material inhomogeneity on change in modulus, hardness, contact stiffness, and electrical contact resistance is also discussed. Fracture statistics of carbon fiber and variations in flexural strength of GDL are studied. The damage propagation in CL is perceived to be influenced by the type of gradation and the vicinity from which crack originates. Cohesive zone model has been proposed based on the traction-separation law to investigate the damage propagation throughout the two interfaces (carbon fiber/CL and CL/membrane).

  19. Diffusion tensor imaging of basal ganglia and thalamus in amyotrophic lateral sclerosis.

    Science.gov (United States)

    Sharma, Khema R; Sheriff, Sulaiman; Maudsley, Andrew; Govind, Varan

    2013-07-01

    To assess the involvement of basal ganglia and thalamus in patients with amyotrophic lateral sclerosis (ALS) using diffusion tensor imaging (DTI) method. Fourteen definite-ALS patients and 12 age-matched controls underwent whole brain DTI on a 3T scanner. Mean-diffusivity (MD) and fractional anisotropy (FA) were obtained bilaterally from the basal ganglia and thalamus in the regions-of-interest (ROIs). The MD was significantly higher (P < .02) in basal ganglia and thalamus in patients with ALS compared with controls. Correspondingly, the FA was significantly lower (P < .02) in these structures, except in caudate (P = .04) and putamen (P = .06) in patients compared with controls. There were mild to strong correlations (r = .3-.7) between the DTI measures of basal ganglia and finger-tap, foot-tap, and lip-and-tongue movement rate. The increased MD in basal ganglia and thalamus and decreased FA in globus pallidus and thalamus are indicative of neuronal loss or dysfunction in these structures. Copyright © 2012 by the American Society of Neuroimaging.

  20. Experimental Study of Electrodes Parameters Effects on Small Diffusion Combustion Flame

    Institute of Scientific and Technical Information of China (English)

    Yiting Zhang

    2015-01-01

    To study the configuration and conductivity effects on micro⁃scale methane⁃air flames by electric field and iron wind, different electric field forces and iron winds are generated by needle, circle and plate electrodes respectively in different electrodes heights under both AC and DC fields though experiments. Experimental results showed that the flame characteristics are affected by needle electrodes mainly through the action of ion wind, by plate type electrodes mainly through the action of electric field force and by annular electrodes through both the electric field force and ion wind at the same time. Under DC field ’ s effects of all electrodes types, the flame will consequently go down while the voltage reached to a limit value, and it will breakdown under the strong effect of the ion wind by needle electrodes. The results also showed the influence by different electrodes types to the current characteristics, resistance properties and configuration of themicro⁃scale flames.

  1. Production method of raw material dispersion liquid for reaction layer of gas diffusion electrode

    Energy Technology Data Exchange (ETDEWEB)

    Furuya, Choichi; Motoo, Satoshi

    1987-10-13

    Heretofore, in order to make a raw material dispersion liquid of a reaction layer of a gas diffusion electrode, water repellent carbon, polytetrafluoroethylene, water and a surface active agent are mixed, then a cake is made by filtering this mixed liquid and afterwards the cake is heated and dried before being crushed. Since this crushing is done mechanically, homogeneous fine raw material powders cannot be obtained. Accordingly, even when a reaction layer is made by sintering a mixture of this powder, hydrophilic carbon black or hydrophilic carbon black carrying catalyst, and polytetrafluoroethylene, the hydrophilic part and the water repellent part are not distributed homogeneously and the catalytic performance of the reaction layer declines. In order to solve this, this invention proposes a production method that water repellent carbon black, polyterafluoroethylene, water and a surface active agent are mixed, then this mixture is frozen so that the surface active agent may not become active and homogeneous condensed cores of water repellent carbon black and polytetrafluoroethylene powders may be formed, and afterwards a homogeneous fine raw material dispersion liquid is made from thawing the condensed cores without change by thawing the above frozen mixture.

  2. Electrochemical Properties of Electrodes with Different Shapes and Diffusion Kinetic Analysis of Microbial Fuel Cells on Ocean Floor

    Institute of Scientific and Technical Information of China (English)

    FU Yubin; LIU Jia; SU Jia; ZHAO Zhongkai; LIU Yang; XU Qian

    2012-01-01

    Microbial fuel cell (MFC) on the ocean floor is a kind of novel energy- harvesting device that can be developed to drive small instruments to work continuously.The shape of electrode has a great effect on the performance of the MFC.In this paper,several shapes of electrode and cell structure were designed,and their performance in MFC were compared in pairs:Mesh (cell-1) vs.flat plate (cell-2),branch (cell-3) vs.cylinder (cell-4),and forest (cell-5) vs.disk (cell-6) FC.Our results showed that the maximum power densities were 16.50,14.20,19.30,15.00,14.64,and 9.95 mWm-2 for cell-l,2,3,4,5 and 6 respectively.And the corresponding diffusion-limited currents were 7.16,2.80,18.86,10.50,18.00,and 6.900 mA.The mesh and branch anodes showed higher power densities and much higher diffusion-limited currents than the flat plate and the cylinder anodes respectively due to the low diffusion hindrance with the former anodes.The forest cathode improved by 47% of the power density and by 161% of diffusionlimited current than the disk cathode due to the former's extended solid/liquid/gas three-phase boundary.These results indicated that the shape of electrode is a major parameter that determining the diffusion-limited current of an MFC,and the differences in the electrode shape lead to the differences in cell performance.These results would be useful for MFC structure design in practical applications.

  3. Notch-mediated lateral inhibition regulates proneural wave propagation when combined with EGF-mediated reaction diffusion.

    Science.gov (United States)

    Sato, Makoto; Yasugi, Tetsuo; Minami, Yoshiaki; Miura, Takashi; Nagayama, Masaharu

    2016-08-30

    Notch-mediated lateral inhibition regulates binary cell fate choice, resulting in salt and pepper patterns during various developmental processes. However, how Notch signaling behaves in combination with other signaling systems remains elusive. The wave of differentiation in the Drosophila visual center or "proneural wave" accompanies Notch activity that is propagated without the formation of a salt and pepper pattern, implying that Notch does not form a feedback loop of lateral inhibition during this process. However, mathematical modeling and genetic analysis clearly showed that Notch-mediated lateral inhibition is implemented within the proneural wave. Because partial reduction in EGF signaling causes the formation of the salt and pepper pattern, it is most likely that EGF diffusion cancels salt and pepper pattern formation in silico and in vivo. Moreover, the combination of Notch-mediated lateral inhibition and EGF-mediated reaction diffusion enables a function of Notch signaling that regulates propagation of the wave of differentiation.

  4. Protein Crowding in Lipid Bilayers Gives Rise to Non-Gaussian Anomalous Lateral Diffusion of Phospholipids and Proteins

    Science.gov (United States)

    Jeon, Jae-Hyung; Javanainen, Matti; Martinez-Seara, Hector; Metzler, Ralf; Vattulainen, Ilpo

    2016-04-01

    Biomembranes are exceptionally crowded with proteins with typical protein-to-lipid ratios being around 1 ∶50 -1 ∶100 . Protein crowding has a decisive role in lateral membrane dynamics as shown by recent experimental and computational studies that have reported anomalous lateral diffusion of phospholipids and membrane proteins in crowded lipid membranes. Based on extensive simulations and stochastic modeling of the simulated trajectories, we here investigate in detail how increasing crowding by membrane proteins reshapes the stochastic characteristics of the anomalous lateral diffusion in lipid membranes. We observe that correlated Gaussian processes of the fractional Langevin equation type, identified as the stochastic mechanism behind lipid motion in noncrowded bilayer, no longer adequately describe the lipid and protein motion in crowded but otherwise identical membranes. It turns out that protein crowding gives rise to a multifractal, non-Gaussian, and spatiotemporally heterogeneous anomalous lateral diffusion on time scales from nanoseconds to, at least, tens of microseconds. Our investigation strongly suggests that the macromolecular complexity and spatiotemporal membrane heterogeneity in cellular membranes play critical roles in determining the stochastic nature of the lateral diffusion and, consequently, the associated dynamic phenomena within membranes. Clarifying the exact stochastic mechanism for various kinds of biological membranes is an important step towards a quantitative understanding of numerous intramembrane dynamic phenomena.

  5. Degradation mechanism of diethyl phthalate with electrogenerated hydroxyl radical on a Pd/C gas-diffusion electrode

    Energy Technology Data Exchange (ETDEWEB)

    Wang Hui, E-mail: wanghui616@gmail.com [College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083 (China); Sun Dezi [College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083 (China); Bian Zhaoyng, E-mail: bzy@mail.ipc.ac.cn [Key Laboratory of Photochemical Conversion and Optoelectronic Materials, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

    2010-08-15

    Using a self-made Pd/C gas-diffusion electrode as the cathode and a Ti/IrO{sub 2}/RuO{sub 2} anode, the degradation of diethyl phthalate (DEP) has been investigated in an undivided electrolysis device by electrochemical oxidation processes. Hydroxyl radical (HO{center_dot}) was determined in the reaction mixture by the electron spin resonance spectrum (ESR). The result indicated that the Pd/C catalyst in Pd/C gas-diffusion electrode system accelerated the two-electron reduction of fed O{sub 2} to H{sub 2}O{sub 2}, which is in favor of producing HO{center_dot}. Additionally, the percentage removal of DEP and COD reached about 80.9 and 40.2% after 9 h electrolysis, respectively. It suggested that most of DEP were oxidized to intermediates using the Pd/C gas-diffusion electrode. Furthermore, the ratio of BOD{sub 5}/COD of resulted solutions was three times larger than the initial ones. Hence, the electrochemical oxidation enhanced the biodegradation character of the DEP solution. Finally, main aromatic intermediates (e.g., monoethyl phthalate (MEP) and phthalic acid (PA)) and main aliphatic carboxylic intermediates (e.g., formic, mesoxalic, oxalic, malonic, succinic, maleic, dodecanoic, and hexadecanoic acids) were identified by GC-MS. Moreover, a reaction scheme involving all these intermediates was proposed.

  6. Degradation mechanism of diethyl phthalate with electrogenerated hydroxyl radical on a Pd/C gas-diffusion electrode.

    Science.gov (United States)

    Wang, Hui; Sun, De-Zhi; Bian, Zhao-Yong

    2010-08-15

    Using a self-made Pd/C gas-diffusion electrode as the cathode and a Ti/IrO(2)/RuO(2) anode, the degradation of diethyl phthalate (DEP) has been investigated in an undivided electrolysis device by electrochemical oxidation processes. Hydroxyl radical (HO) was determined in the reaction mixture by the electron spin resonance spectrum (ESR). The result indicated that the Pd/C catalyst in Pd/C gas-diffusion electrode system accelerated the two-electron reduction of fed O(2) to H(2)O(2), which is in favor of producing HO. Additionally, the percentage removal of DEP and COD reached about 80.9 and 40.2% after 9h electrolysis, respectively. It suggested that most of DEP were oxidized to intermediates using the Pd/C gas-diffusion electrode. Furthermore, the ratio of BOD(5)/COD of resulted solutions was three times larger than the initial ones. Hence, the electrochemical oxidation enhanced the biodegradation character of the DEP solution. Finally, main aromatic intermediates (e.g., monoethyl phthalate (MEP) and phthalic acid (PA)) and main aliphatic carboxylic intermediates (e.g., formic, mesoxalic, oxalic, malonic, succinic, maleic, dodecanoic, and hexadecanoic acids) were identified by GC-MS. Moreover, a reaction scheme involving all these intermediates was proposed. Copyright 2010 Elsevier B.V. All rights reserved.

  7. Design and analysis of compact ultra energy-efficient logic gates using laterally-actuated double-electrode NEMS

    KAUST Repository

    Dadgour, Hamed F.

    2010-01-01

    Nano-Electro-Mechanical Switches (NEMS) are among the most promising emerging devices due to their near-zero subthreshold-leakage currents. This paper reports device fabrication and modeling, as well as novel logic gate design using "laterally-actuated double-electrode NEMS" structures. The new device structure has several advantages over existing NEMS architectures such as being immune to impact bouncing and release vibrations (unlike a vertically-actuated NEMS) and offer higher flexibility to implement compact logic gates (unlike a single-electrode NEMS). A comprehensive analytical framework is developed to model different properties of these devices by solving the Euler-Bernoulli\\'s beam equation. The proposed model is validated using measurement data for the fabricated devices. It is shown that by ignoring the non-uniformity of the electrostatic force distribution, the existing models "underestimate" the actual value of Vpull-in and Vpull-out. Furthermore, novel energy efficient NEMS-based circuit topologies are introduced to implement compact inverter, NAND, NOR and XOR gates. For instance, the proposed XOR gate can be implemented by using only two NEMS devices compared to that of a static CMOS-based XOR gate that requires at least 10 transistors. © Copyright 2010 ACM.

  8. Lateral gas phase diffusion length of boron atoms over Si/B surfaces during CVD of pure boron layers

    NARCIS (Netherlands)

    Mohammadi, V.; Nihtianov, S.

    2016-01-01

    The lateral gas phase diffusion length of boron atoms, LB, along silicon and boron surfaces during chemical vapor deposition(CVD) using diborane (B2H6) is reported. The value of LB is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and co

  9. Lateral gas phase diffusion length of boron atoms over Si/B surfaces during CVD of pure boron layers

    NARCIS (Netherlands)

    Mohammadi, V.; Nihtianov, S.

    2016-01-01

    The lateral gas phase diffusion length of boron atoms, LB, along silicon and boron surfaces during chemical vapor deposition(CVD) using diborane (B2H6) is reported. The value of LB is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and co

  10. Generation of large-scale, barrier-free diffuse plasmas in air at atmospheric pressure using array wire electrodes and nanosecond high-voltage pulses

    Science.gov (United States)

    Teng, Yun; Li, Lee; Liu, Yun-Long; Liu, Lun; Liu, Minghai

    2014-10-01

    This paper introduces a method to generate large-scale diffuse plasmas by using a repetition nanosecond pulse generator and a parallel array wire-electrode configuration. We investigated barrier-free diffuse plasmas produced in the open air in parallel and cross-parallel array line-line electrode configurations. We found that, when the distance between the wire-electrode pair is small, the discharges were almost extinguished. Also, glow-like diffuse plasmas with little discharge weakening were obtained in an appropriate range of line-line distances and with a cathode-grounding cross-electrode configuration. As an example, we produced a large-scale, stable diffuse plasma with volumes as large as 18 × 15 × 15 cm3, and this discharge region can be further expanded. Additionally, using optical and electrical measurements, we showed that the electron temperature was higher than the gas temperature, which was almost the same as room temperature. Also, an array of electrode configuration with more wire electrodes had helped to prevent the transition from diffuse discharge to arc discharge. Comparing the current waveforms of configurations with 1 cell and 9 cells, we found that adding cells significantly increased the conduction current and the electrical energy delivered in the electrode gaps.

  11. Investigation of Top/Bottom electrode and Diffusion Barrier Layer for PZT Thick Film MEMS Sensors

    DEFF Research Database (Denmark)

    Hindrichsen, Christian Carstensen; Pedersen, Thomas; Thomsen, Erik Vilain

    2008-01-01

    Top and bottom electrodes for screen printed piezoelectric lead zirconate titanate, Pb(ZrxTi1 - x)O3 (PZT) thick film are investigated with respect to future MEMS devices. Down to 100 nm thick E-beam evaporated Al and Pt films are patterned as top electrodes on the PZT using a lift-off process...

  12. Coupling Optical and Electrical Measurements in Artificial Membranes: Lateral Diffusion of Lipids and Channel Forming Peptides in Planar Bilayers

    Directory of Open Access Journals (Sweden)

    Duclohier H

    1998-01-01

    Full Text Available Planar lipid bilayers (PLB were prepared by the Montal-Mueller technique in a FRAP system designed to simultaneously measure conductivity across, and lateral diffusion of, the bilayer. In the first stage of the project the FRAP system was used to characterise the lateral dynamics of bilayer lipids with regards to phospholipid composition (headgroup, chain unsaturation etc., presence of cholesterol and the effect of divalent cations on negatively-charged bilayers. In the second stage of the project, lateral diffusion of two fluorescently-labelled voltage-dependent pore-forming peptides (alamethicin and S4s from Shaker K+ channel was determined at rest and in the conducting state. This study demonstrates the feasibility of such experiments with PLBs, amenable to physical constraints, and thus offers new opportunities for systematic studies of structure-function relationships in membrane-associating molecules.

  13. Lateral diffusion contributes to FRET from lanthanide-tagged membrane proteins.

    Science.gov (United States)

    Lan, Tien-Hung; Wu, Guangyu; Lambert, Nevin A

    2015-08-14

    Diffusion can enhance Förster resonance energy transfer (FRET) when donors or acceptors diffuse distances that are similar to the distances separating them during the donor's excited state lifetime. Lanthanide donors remain in the excited state for milliseconds, which makes them useful for time-resolved FRET applications but also allows time for diffusion to enhance energy transfer. Here we show that diffusion dramatically enhances FRET between membrane proteins labeled with lanthanide donors. This phenomenon complicates interpretation of experiments that use long-lived donors to infer association or proximity of mobile membrane proteins, but also offers a method of monitoring diffusion in membrane domains in real time in living cells.

  14. Study of polyaniline doped with trifluoromethane sulfonic acid in gas-diffusion electrodes for proton-exchange membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Gharibi, Hussein; Zhiani, Mohammad; Kheirmand, Mehdi; Kakaei, Karim [Department of Physical Chemistry, Faculty of Science, Tarbiat Modarres University, P.O. Box 14115-175, Tehran (Iran); Entezami, Ali Akbar [Faculty of Chemistry, Tabriz University, Tabriz (Iran); Mirzaie, Rasol Abdullah [Department of Chemistry, Faculty of Science, Shahid Rajaee University, Tehran (Iran)

    2006-04-21

    Polytetrafluoroethylene (PTFE)-bonded gas-diffusion electrodes (GDEs), modified with polyaniline as an electron and proton conductor in the catalyst layer, are prepared and evaluated for use in proton-exchange membrane fuel cells (PEMFCs). Polyaniline is coated on the GDE by electropolymerization of aniline and trifluoromethane sulfonic acid as the proton-conductive monomer. The electrodes are characterized by cyclic voltammetry, current-potential measurements, electrochemical impedance spectroscopy, and chronoamperometry. The polyaniline is found to be homogenously dispersed in the catalyst layer, making it a good candidate proton and electron conductor. Use of polyaniline instead of Nafion in the catalyst layer, increases the utility of the electrocatalyst by 18%. The results are consistent with the presence of polyaniline as a conductive polymer in the reaction layer reducing the polarization resistance of the electrode in comparison with that of a corresponding electrode containing Nafion. Thus, the present results indicate that PEMFCs using polyaniline-containing electrocatalysts should give superior performance to those using catalysts containing traditional ionomers. (author)

  15. Lateral diffusion of the topological charge density in stochastic optical fields

    CSIR Research Space (South Africa)

    Roux, FS

    2010-01-01

    Full Text Available is described by a diffusion process that has a diffusion parameter which depends on the propagation distance. Keywords: optical vortex, singular optics, stochastic optical field, topological charge density, diffusion equation 1. Introduction The spatial... [1, 2], which measures the continuous phase distortions and then removes them with a continuous deformable mirror. The problem with this approach comes in with strong scintillation, when the phase distortions are severe enough to give rise...

  16. Lateral diffusion contributes to FRET from lanthanide-tagged membrane proteins

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Tien-Hung; Wu, Guangyu; Lambert, Nevin A., E-mail: nelambert@gru.edu

    2015-08-14

    Diffusion can enhance Förster resonance energy transfer (FRET) when donors or acceptors diffuse distances that are similar to the distances separating them during the donor's excited state lifetime. Lanthanide donors remain in the excited state for milliseconds, which makes them useful for time-resolved FRET applications but also allows time for diffusion to enhance energy transfer. Here we show that diffusion dramatically enhances FRET between membrane proteins labeled with lanthanide donors. This phenomenon complicates interpretation of experiments that use long-lived donors to infer association or proximity of mobile membrane proteins, but also offers a method of monitoring diffusion in membrane domains in real time in living cells. - Highlights: • Diffusion enhances TR-FRET from membrane proteins labeled with lanthanide donors. • Diffusion-dependent FRET can overshadow FRET due to oligomerization or clustering. • FRET studies using lanthanide-tagged membrane proteins should consider diffusion. • FRET from lanthanide donors can be used to monitor membrane protein diffusion.

  17. Effects of cholesterol on lateral diffusion and vertical fluctuations in lipid bilayers. An electron-electron double resonance (ELDOR) study

    Energy Technology Data Exchange (ETDEWEB)

    Yin, J.J.; Feix, J.B.; Hyde, J.S.

    1987-12-01

    Electron-electron double resonance (ELDOR) and saturation-recovery spectroscopy employing /sup 14/N:/sup 15/N stearic acid spin-label pairs have been used to study the effects of cholesterol on lateral diffusion and vertical fluctuations in lipid bilayers. The /sup 14/N:/sup 15/N continuous wave electron-electron double resonance (CW ELDOR) theory has been developed using rate equations based on the relaxation model. The collision frequency between /sup 14/N-16 doxyl stearate and /sup 15/N-16 doxyl stearate, WHex (16:16), is indicative of lateral diffusion of the spin probes, while the collision frequency between /sup 14/N-16 doxyl stearate and /sup 15/N-5 doxyl stearate, WHex (16:5), provides information on vertical fluctuations of the /sup 14/N-16 doxyl stearate spin probe toward the membrane surface. Our results show that: (a) cholesterol decreases the electron spin-lattice relaxation time Tle of /sup 14/N-16 doxyl stearate spin label in dimyristoylphosphatidylcholine (DMPC) and egg yolk phosphatidylcholine (egg PC). (b) Cholesterol increases the biomolecular collision frequency WHex (16:16) and decreases WHex (16:5), suggesting that incorporation of cholesterol significantly orders the part of the bilayer that it occupies and disorders the interior region of the bilayer. (c) Alkyl chain unsaturation of the host lipid moderates the effect of cholesterol on both vertical fluctuations and lateral diffusion of /sup 14/N-16 doxyl stearate. And (d), there are marked differences in the effects of cholesterol on lateral diffusion and vertical fluctuations between 0-30 mol% and 30-50 mol% of cholesterol that suggest an inhomogeneous distribution of cholesterol in the membrane.

  18. Gas Diffusion Electrodes Manufactured by Casting Evaluation as Air Cathodes for Microbial Fuel Cells (MFC

    Directory of Open Access Journals (Sweden)

    Sandipam Srikanth

    2016-07-01

    Full Text Available One of the most intriguing renewable energy production methods being explored currently is electrical power generation by microbial fuel cells (MFCs. However, to make MFC technology economically feasible, cost efficient electrode manufacturing processes need to be proposed and demonstrated. In this context, VITO has developed an innovative electrode manufacturing process based on film casting and phase inversion. The screening and selection process of electrode compositions was done based on physicochemical properties of the active layer, which in turn maintained a close relation with their composition A dual hydrophilic-hydrophobic character in the active layer was achieved with values of εhydrophilic up to 10% while εTOTAL remained in the range 65 wt % to 75 wt %. Eventually, selected electrodes were tested as air cathodes for MFC in half cell and full cell modes. Reduction currents, up to −0.14 mA·cm2− at −100 mV (vs. Ag/AgCl were reached in long term experiments in the cathode half-cell. In full MFC, a maximum power density of 380 mW·m−2 was observed at 100 Ω external load.

  19. Hydrogen diffusion in La{sub 1.5}Nd{sub 0.5}MgNi{sub 9} alloy electrodes of the Ni/MH battery

    Energy Technology Data Exchange (ETDEWEB)

    Volodin, A.A. [Institute of Problems of Chemical Physics of RAS, Chernogolovka (Russian Federation); Denys, R.V. [Institute for Energy Technology, P.O. Box 40, Kjeller NO2027 (Norway); Tsirlina, G.A. [Department of Electrochemistry, Moscow State University, Moscow (Russian Federation); Tarasov, B.P. [Institute of Problems of Chemical Physics of RAS, Chernogolovka (Russian Federation); Fichtner, M. [Institute of Nanotechnology, Karlsruhe Institute of Technology, Karlsruhe (Germany); Yartys, V.A., E-mail: volodymyr.yartys@ife.no [Institute for Energy Technology, P.O. Box 40, Kjeller NO2027 (Norway)

    2015-10-05

    Highlights: • Hydrogen diffusion in the La{sub 1.5}Nd{sub 0.5}MgNi{sub 9} alloy electrode was studied. • Various techniques of low amplitude potentiostatic data treatment were used. • D{sub H} demonstrates a maximum (2 × 10{sup −11} cm{sup 2}/s) at 85% of discharge of the electrode. • Maximum is associated with a conversion of β-hydride into a solid α-solution. • Optimization of material and electrode will allow high discharge rates. - Abstract: Hydrogen diffusion in the La{sub 1.5}Nd{sub 0.5}MgNi{sub 9} battery electrode material has been studied using low amplitude potentiostatic experiments. Complex diffusion behavior is examined in frames of electroanalytical models proposed for the lithium intercalation materials. Hydrogen diffusion coefficient D{sub H} changes with hydrogen content in the metal hydride anode electrode and has a maximum of ca. 2 × 10{sup −11} cm{sup 2}/s at ca. 85% of discharge. Such a behavior differs from the trends known for the transport in lithium battery materials, but qualitatively agrees with the data for the highly concentrated β-PdH{sub x}.

  20. Towards combined electrochemistry and surface-enhanced resonance Raman of heme proteins: Improvement of diffusion electrochemistry of cytochrome c at silver electrodes chemically modified with 4-mercaptopyridine.

    Science.gov (United States)

    Millo, Diego; Ranieri, Antonio; Koot, Wynanda; Gooijer, Cees; van der Zwan, Gert

    2006-08-01

    To date, a successful combination of surface-enhanced resonance Raman spectroscopy (SERRS) and electrochemistry to study heme proteins is inhibited by the problems raised by the prerequisite to use silver as electrode metal. This paper indicates an approach to overcome these problems. It describes a quick and reproducible procedure to prepare silver electrodes chemically modified with 4-mercaptopyridine suitable to perform diffusion electrochemistry of cytochrome c (cyt c). The method involves the employment of a mechanical and a chemical treatment and avoids the use of alumina slurries and any electrochemical pretreatment. Cyclic voltammetry (CV) was used to test the electrochemical response of cyt c, and the CV signals were found identical with those obtained on gold electrodes under the same experimental conditions. Compared to previous literature, a significant improvement of the CV signal of cyt c at silver electrodes was achieved. Preliminary results show that this treatment can be also successfully employed for the preparation of SERRS-active electrodes.

  1. Confinement, Desolvation, And Electrosorption Effects on the Diffusion of Ions in Nanoporous Carbon Electrodes.

    Science.gov (United States)

    Pean, Clarisse; Daffos, Barbara; Rotenberg, Benjamin; Levitz, Pierre; Haefele, Matthieu; Taberna, Pierre-Louis; Simon, Patrice; Salanne, Mathieu

    2015-10-07

    Supercapacitors are electrochemical devices which store energy by ion adsorption on the surface of a porous carbon. They are characterized by high power delivery. The use of nanoporous carbon to increase their energy density should not hinder their fast charging. However, the mechanisms for ion transport inside electrified nanopores remain largely unknown. Here we show that the diffusion is characterized by a hierarchy of time scales arising from ion confinement, solvation, and electrosorption effects. By combining electrochemistry experiments with molecular dynamics simulations, we determine the in-pore conductivities and diffusion coefficients and their variations with the applied potential. We show that the diffusion of the ions is slower by 1 order of magnitude compared to the bulk electrolyte. The desolvation of the ions occurs on much faster time scales than electrosorption.

  2. Fast spatiotemporal correlation spectroscopy to determine protein lateral diffusion laws in live cell membranes.

    Science.gov (United States)

    Di Rienzo, Carmine; Gratton, Enrico; Beltram, Fabio; Cardarelli, Francesco

    2013-07-23

    Spatial distribution and dynamics of plasma-membrane proteins are thought to be modulated by lipid composition and by the underlying cytoskeleton, which forms transient barriers to diffusion. So far this idea was probed by single-particle tracking of membrane components in which gold particles or antibodies were used to individually monitor the molecules of interest. Unfortunately, the relatively large particles needed for single-particle tracking can in principle alter the very dynamics under study. Here, we use a method that makes it possible to investigate plasma-membrane proteins by means of small molecular labels, specifically single GFP constructs. First, fast imaging of the region of interest on the membrane is performed. For each time delay in the resulting stack of images the average spatial correlation function is calculated. We show that by fitting the series of correlation functions, the actual protein "diffusion law" can be obtained directly from imaging, in the form of a mean-square displacement vs. time-delay plot, with no need for interpretative models. This approach is tested with several simulated 2D diffusion conditions and in live Chinese hamster ovary cells with a GFP-tagged transmembrane transferrin receptor, a well-known benchmark of membrane-skeleton-dependent transiently confined diffusion. This approach does not require extraction of the individual trajectories and can be used also with dim and dense molecules. We argue that it represents a powerful tool for the determination of kinetic and thermodynamic parameters over very wide spatial and temporal scales.

  3. Uncinate fasciculus microstructure and verbal episodic memory in amyotrophic lateral sclerosis: a diffusion tensor imaging and neuropsychological study.

    Science.gov (United States)

    Christidi, Foteini; Zalonis, Ioannis; Kyriazi, Stavroula; Rentzos, Michalis; Karavasilis, Efstratios; Wilde, Elisabeth A; Evdokimidis, Ioannis

    2014-12-01

    The present study evaluates the integrity of uncinate fasciculus (UF) and the association between UF microstructure and verbal episodic memory (as one of the cognitive functions linked to UF) in non-demented patients with amyotrophic lateral sclerosis (ALS) using diffusion tensor imaging (DTI). We studied 21 patients with ALS and 11 healthy, demographically-comparable volunteers. Fractional anisotropy, apparent diffusion coefficient, axial and radial diffusivity were the DTI metrics examined. Episodic memory was evaluated with Babcock Story Recall Test and Rey Auditory Verbal Learning Test (RAVLT) for patients; measures of immediate and delayed recall and retention for both tests and sum of words recalled through five learning trials for RAVLT were considered. Patients with ALS showed significant bilateral reduction of axial diffusivity in the UF as compared to controls. Furthermore, there were several significant relations between various DTI metrics (mostly in left hemisphere) and memory measures (specifically for the RAVLT). UF microstructural changes may contribute to ALS-related memory impairment, with word-list learning performance relying more upon the integrity of frontal and temporal connections than memory components associated with story recall.

  4. Diffusion tensor imaging for long-term follow-up of corticospinal tract degeneration in amyotrophic lateral sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Jacob, S.; Ehrenreich, H. [Max-Planck-Institute for Experimental Medicine, Georg-August-University, Hermann-Rein-Strasse 3, 37075, Goettingen (Germany); Departments of Neurology and Psychiatry, Georg-August-University, Goettingen (Germany); Finsterbusch, J.; Frahm, J. [Biomedizinische NMR Forschungs GmbH, Max-Planck-Institute for Biophysical Chemistry, Georg-August-University, Goettingen (Germany); Weishaupt, J.H. [Departments of Neurology and Psychiatry, Georg-August-University, Goettingen (Germany); Khorram-Sefat, D. [Department of Neuroradiology, Georg-August-University, Goettingen (Germany)

    2003-09-01

    Amyotrophic lateral sclerosis (ALS) is a predominantly clinical and electromyographic diagnosis. Conventional MRI reveals atrophy of the motor system, particularly the pyramidal tract, in the advanced stages but does not provide a sensitive measure of disease progression. Three patients with different principal symptoms of ALS, i.e., with predominant involvement of the upper (UMN) or lower (UMN) motor neurons, or bulbar disease, respectively, underwent serial clinical examination including lung function tests, conventional MRI, and diffusion tensor imaging (DTI). MRI demonstrated changes in of the pyramidal tract without measurable variation on follow-up. The patient with UMN involvement showed remarkable progressive loss of diffusion anisotropy in the pyramidal tract. DTI might be useful, together with clinical follow-up, as an objective morphological marker in therapeutic trials. (orig.)

  5. Hydrogen Oxidation on Gas Diffusion Electrodes for Phosphoric Acid Fuel Cells in the Presence of Carbon Monoxide and Oxygen

    DEFF Research Database (Denmark)

    Gang, Xiao; Li, Qingfeng; Hjuler, Hans Aage

    1995-01-01

    Hydrogen oxidation has been studied on a carbon-supported platinum gas diffusion electrode in a phosphoric acidelectrolyte in the presence of carbon monoxide and oxygen in the feed gas. The poisoning effect of carbon monoxide presentin the feed gas was measured in the temperature range from 80...... to 150°C. It was found that throughout the temperaturerange, the potential loss due to the CO poisoning can be reduced to a great extent by the injection of small amounts ofgaseous oxygen into the hydrogen gas containing carbon monoxide. By adding 5 volume percent (v/o) oxygen, an almost......CO-free performance can be obtained for carbon monoxide concentrations up to 0.5 v/o CO at 130°C, 0.2 v/o CO at 100°C,and 0.1 v/o CO at 80°C, respectively....

  6. Lateral Diffusion of Membrane Proteins : Consequences of Hydrophobic Mismatch and Lipid Composition

    NARCIS (Netherlands)

    Ramadurai, Sivaramakrishnan; Duurkens, Hinderika; Krasnikov, Victor V.; Poolman, Bert

    2010-01-01

    Biological membranes are composed of a large number lipid species differing in hydrophobic length, degree of saturation, and charge and size of the headgroup. We now present data on the effect of hydrocarbon chain length of the lipids and headgroup composition on the lateral mobility of the proteins

  7. Eliminating micro-porous layer from gas diffusion electrode for use in high temperature polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Su, Huaneng; Xu, Qian; Chong, Junjie; Li, Huaming; Sita, Cordellia; Pasupathi, Sivakumar

    2017-02-01

    In this work, we report a simple strategy to improve the performance of high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) by eliminating the micro-porous layer (MPL) from its gas diffusion electrodes (GDEs). Due to the absence of liquid water and the general use of high amount of catalyst, the MPL in a HT-PEMFC system works limitedly. Contrarily, the elimination of the MPL leads to an interlaced micropore/macropore composited structure in the catalyst layer (CL), which favors gas transport and catalyst utilization, resulting in a greatly improved single cell performance. At the normal working voltage (0.6 V), the current density of the GDE eliminated MPL reaches 0.29 A cm-2, and a maximum power density of 0.54 W cm-2 at 0.36 V is obtained, which are comparable to the best results yet reported for the HT-PEMFCs with similar Pt loading and operated using air. Furthermore, the MPL-free GDE maintains an excellent durability during a preliminary 1400 h HT-PEMFC operation, owing to its structure advantages, indicating the feasibility of this electrode for practical applications.

  8. Diffusion-Controlled Current at the Stationary Finite Disk Electrode. Theory.

    Science.gov (United States)

    1980-10-01

    Journal of Electroanalytical Chemistry 19. KEY WORDS (Continue on rev’erse aid& If necessa~ry and idfentlify b block number) diffusion-controlled...Publication in the Journal of Electroanalytical Chemistry State University of New York at Buffalo Department of Chemistry Buffalo, New York October, 1980...Tokuda and G. P. Sat6, 25th Annual Meeting on Polarography and Electroanalytical Chemistry , Oct. 5th- 6th, 1979, Kobe. 10. G. P. Sato, M. Kakihana, H

  9. A model for membrane patchiness: lateral diffusion in the presence of barriers and vesicle traffic.

    OpenAIRE

    Gheber, L A; Edidin, M

    1999-01-01

    Patches (lateral heterogeneities) of cell surface membrane proteins and lipids have been imaged by a number of different microscopy techniques. This patchiness has been taken as evidence for the organization of membranes into domains whose composition differs from the average for the entire membrane. However, the mechanism and specificity of patch formation are not understood. Here we show how vesicle traffic to and from a cell surface membrane can create patches of molecules of the size obse...

  10. Electrode Materials, Thermal Annealing Sequences, and Lateral/Vertical Phase Separation of Polymer Solar Cells from Multiscale Molecular Simulations

    KAUST Repository

    Lee, Cheng-Kuang

    2014-12-10

    © 2014 American Chemical Society. The nanomorphologies of the bulk heterojunction (BHJ) layer of polymer solar cells are extremely sensitive to the electrode materials and thermal annealing conditions. In this work, the correlations of electrode materials, thermal annealing sequences, and resultant BHJ nanomorphological details of P3HT:PCBM BHJ polymer solar cell are studied by a series of large-scale, coarse-grained (CG) molecular simulations of system comprised of PEDOT:PSS/P3HT:PCBM/Al layers. Simulations are performed for various configurations of electrode materials as well as processing temperature. The complex CG molecular data are characterized using a novel extension of our graph-based framework to quantify morphology and establish a link between morphology and processing conditions. Our analysis indicates that vertical phase segregation of P3HT:PCBM blend strongly depends on the electrode material and thermal annealing schedule. A thin P3HT-rich film is formed on the top, regardless of bottom electrode material, when the BHJ layer is exposed to the free surface during thermal annealing. In addition, preferential segregation of P3HT chains and PCBM molecules toward PEDOT:PSS and Al electrodes, respectively, is observed. Detailed morphology analysis indicated that, surprisingly, vertical phase segregation does not affect the connectivity of donor/acceptor domains with respective electrodes. However, the formation of P3HT/PCBM depletion zones next to the P3HT/PCBM-rich zones can be a potential bottleneck for electron/hole transport due to increase in transport pathway length. Analysis in terms of fraction of intra- and interchain charge transports revealed that processing schedule affects the average vertical orientation of polymer chains, which may be crucial for enhanced charge transport, nongeminate recombination, and charge collection. The present study establishes a more detailed link between processing and morphology by combining multiscale molecular

  11. Degradation of 4-chlorophenol by the anodic-cathodic cooperative effect with a Pd/MWNT gas-diffusion electrode.

    Science.gov (United States)

    Wang, H; Wei, X J; Bian, Z Y

    2012-01-01

    Pd/multi-walled carbon nanotubes (MWNTs) catalyst used for the gas-diffusion electrode was prepared by ethylene glycol (EG) reduction and characterized by the X-ray diffraction (XRD) and scanning electron microscope (SEM). The results indicated that Pd particles with an average size of 8.0 nm were highly dispersed in the MWNTs with amorphous structure. In a diaphragm electrolysis system with a Ti/RuO(2)/IrO(2) anode and the Pd/MWNT gas diffusion cathode, the degradation of 4-chlorophenol was performed by a combination of electrochemical reduction and oxidation. The combined process was in favor of improving 4-chlorophenol degradation efficiency. The optimum reaction conditions were as following: initial pH 7, aeration with hydrogen and air. Under the optimized electrolysis conditions the removal of 4-chlorophenol in the anodic and cathodic compartments were 98.5 and 90.5%, respectively. Additionally, based on the analysis of electrolysis intermediates using high performance liquid chromatography (HPLC) and ion chromatography (IC), the electrolysis degradation of 4-chlorophenol was proposed containing the intermediates, such as phenol, hydroquinone, benzoquinone, maleic acid, fumaric acid, succinic acid, malonic acid, oxalic acid, acetic acid and formic acid.

  12. Silver nanoparticle-decorated carbon nanotubes as bifunctional gas-diffusion electrodes for zinc-air batteries

    Science.gov (United States)

    Wang, T.; Kaempgen, M.; Nopphawan, P.; Wee, G.; Mhaisalkar, S.; Srinivasan, M.

    Thin, lightweight, and flexible gas-diffusion electrodes (GDEs) based on freestanding entangled networks of single-walled carbon nanotubes (SWNTs) decorated with Ag nanoparticles (AgNPs) are tested as the air-breathing cathode in a zinc-air battery. The SWNT networks provide a highly porous surface for active oxygen absorption and diffusion. The high conductivity of SWNTs coupled with the catalytic activity of AgNPs for oxygen reduction leads to an improvement in the performance of the zinc-air cell. By modulating the pH value and the reaction time, different sizes of AgNPs are decorated uniformly on the SWNTs, as revealed by transmission electron microscopy and powder X-ray diffraction. AgNPs with sizes of 3-5 nm double the capacity and specific energy of a zinc-air battery as compared with bare SWNTs. The simplified, lightweight architecture shows significant advantages over conventional carbon-based GDEs in terms of weight, thickness and conductivity, and hence may be useful for mobile and portable applications.

  13. Lectin receptors on the plasma membrane of soybean cells. Binding and lateral diffusion of lectins.

    Science.gov (United States)

    Metcalf, T N; Wang, J L; Schubert, K R; Schindler, M

    1983-08-02

    Protoplasts prepared from suspension cultures of root cells of Glycine max (SB-1 cell line) bound soybean agglutinin (SBA), concanavalin A (Con A), and wheat germ agglutinin (WGA). Binding studies carried out with 125I-labeled SBA, Con A, and WGA showed that these interactions were saturable and specific. Fluorescence microscopy demonstrated uniform membrane labeling. The mobility of the lectin-receptor complexes was measured by fluorescence redistribution after photobleaching. The diffusion constants (D) for SBA and Con A were 5 X 10(-11) and 7 X 10(-11) cm2/s, respectively. In contrast, WGA yielded a diffusion constant of 3 X 10(-10) cm2/s. Pretreatment of the protoplasts with either SBA or Con A resulted in a 6-fold reduction in the mobility of WGA (D congruent to 5 X 10(-11) cm2/s). The results suggest that the binding of SBA or Con A may lead to alterations of the soybean plasma membrane which, in turn, may restrict the mobility of other receptors.

  14. Modeling of Gas Diffusion in Ni/YSZ Electrodes in CO2 and Co-electrolysis

    DEFF Research Database (Denmark)

    Duhn, Jakob Dragsbæk; Jensen, Anker Degn; Wedel, Stig

    2017-01-01

    , pore diameter, current density, pitch and rib width has been investigated. It is shown that diffusion limitations on reactant/product transport may lead to carbon formation. The parameters describing the microstructure and the dimensions of the cathode channels and interconnect ribs are found to have...... a large effect on the carbon formation propensity. Given a set of parameters, a simple correlation between the CO mole fraction in the channel and under the interconnect rib, and current density during CO2-electrolysis can be derived. This correlation makes it possible to efficiently integrate...

  15. Measuring localization and diffusion coefficients of basolateral proteins in lateral versus basal membranes using functionalized substrates and kICS analysis

    DEFF Research Database (Denmark)

    Marlar, Saw; Christensen, Eva Arnspang; Pedersen, Gitte Albinus

    2014-01-01

    Micropatterning enabled semiquantitation of basolateral proteins in lateral and basal membranes of the same cell. Lateral diffusion coefficients of basolateral aquaporin-3 (AQP3-EGFP) and EGFP-AQP4 were extracted from “lateral” and “basal” membranes using identical live-cell imaging and k-space I...

  16. Subdiffusion and lateral diffusion coefficient of lipid atoms and molecules in phospholipid bilayers

    CERN Document Server

    Flenner, Elijah; Rheinstadter, Maikel C; Kosztin, Ioan

    2008-01-01

    We use a long, all-atom molecular dynamics (MD) simulation combined with theoretical modeling to investigate the dynamics of selected lipid atoms and lipid molecules in a hydrated diyristoyl-phosphatidylcholine (DMPC) lipid bilayer. From the analysis of a 0.1 $\\mu$s MD trajectory we find that the time evolution of the mean square displacement, [\\delta{r}(t)]^2, of lipid atoms and molecules exhibits three well separated dynamical regions: (i) ballistic, with [\\delta{r}(t)]^2 ~ t^2 for t 30 ns. We propose a memory function approach for calculating [\\delta{r}(t)]^2 over the entire time range extending from the ballistic to the Fickian diffusion regimes. The results are in very good agreement with the ones from the MD simulations. We also examine the implications of the presence of the subdiffusive dynamics of lipids on the self-intermediate scattering function and the incoherent dynamics structure factor measured in neutron scattering experiments.

  17. Determination of H+ diffusion coefficient in the course of H+ response of a W/WO3 pH electrode

    Institute of Scientific and Technical Information of China (English)

    CHEN Dongchu; FU Zhaoyang; ZHENG Jiashen

    2005-01-01

    A W/WO3 pH electrode was prepared by a method of sol-gel. In order to study the H+ response dynamic mechanism, the electrochemical impedance spectroscopy (EIS) experiment was conducted. It was found that the H+ response course is controlled by the H+ diffusion from the solution to the WO3 film, based on the analysis of EIS spectra. The EIS and potential step method were used to determinate the H+ diffusion coefficient (D) in the course of H+ response of this W/WO3 electrode, and the values of D calculated by these two method correspond very well, which all are about 10-10 cm2/s.The imposed different potential steps make little effect on the calculation of H+ diffusion coefficient, and it was found that the limiting Cottrell equation of short elapsed time fits well to the current transient caused by a potential step, based on the analysis of the time constant.

  18. Discharge mechanism of micro pore gas diffusion electrode%小孔气体扩散电极的放电机理探索

    Institute of Scientific and Technical Information of China (English)

    吴飞; 朱梅; 徐献芝; 宋辉

    2012-01-01

    A kind of gas diffusion electrode was reported by making of nickel film as framework material with different pore sizes. Under the same test condition, the micro pore gas diffusion electrode was compared with nickel foam gas diffusion electrode in the discharge experiment in the zinc-air battery. The discharge polarization curves were drew between electrodes of different size. The results show that the micro pore gas diffusion electrode has a better performance man the nickel foam electrode, reducing the polarization potential under lager current density. The discharge performance has a linear relationship with pore size distribution when the working current density is lower than 1 000 mA/cm2 and exhibits best performance at the pore size about 50 μm. In summary, the discharge performance is improved significantly by changing the inner structure of gas diffusion electrode and shows scale effect with the pore size distribution of electrode. And the intermittent discharge shows little change for its good stability.%借鉴植物叶片高效传输的机理,以包含规则排列的贯通直孔的镍片作为骨架材料,与自制催化剂组成小孔气体扩散电极,在锌空气电池体系下与常规泡沫镍电极的放电性能进行比较,并考察不同孔径的小孔气体扩散电极之间的放电特征.结果表明,小孔气体扩散电极相比泡沫镍电极存在更好的放电性能,降低了电极在大电流密度工作时的极化过电位.当电流密度在低于1 000mA/cm2工作时,放电性能与孔径大小成线性关系,孔径为50μm时,放电效率最佳.总结了小孔气体电极相对泡沫镍气体扩散电极放电效率明显改善,并随着孔径变化放电性能呈现尺度效应,内部结构稳定,间歇放电性能变化较小.

  19. Limitations of the commonly used simplified laterally uniform optical fiber probe-tissue interface in Monte Carlo simulations of diffuse reflectance.

    Science.gov (United States)

    Naglič, Peter; Pernuš, Franjo; Likar, Boštjan; Bürmen, Miran

    2015-10-01

    Light propagation models often simplify the interface between the optical fiber probe tip and tissue to a laterally uniform boundary with mismatched refractive indices. Such simplification neglects the precise optical properties of the commonly used probe tip materials, e.g. stainless steel or black epoxy. In this paper, we investigate the limitations of the laterally uniform probe-tissue interface in Monte Carlo simulations of diffuse reflectance. In comparison to a realistic probe-tissue interface that accounts for the layout and properties of the probe tip materials, the simplified laterally uniform interface is shown to introduce significant errors into the simulated diffuse reflectance.

  20. Use of a mid-scala and a lateral wall electrode in children: insertion depth and hearing preservation.

    Science.gov (United States)

    Benghalem, Abdelhamid; Gazibegovic, Dzemal; Saadi, Fatima; Tazi-Chaoui, Zakia

    2017-01-01

    Atraumatic insertion of the HiFocus(TM) Mid-Scala (HFMS) electrode via the round window was successfully achieved in seven children. Residual hearing 6 months post-operatively was preserved to within 10 dB HL of the pre-operative audiogram at 500 Hz for six children, indicating minimal initial insertion trauma to the cochlea. The objectives were to document the clinical experience and evaluate differences between HFMS and HiFocus(TM) 1j (HF1j) by means of insertion depth and hearing preservation results. Nineteen children were prospectively recruited and consecutively implanted with the HF1j electrode (n = 12) or the HFMS electrode (n = 7) via the round window. Average median angular insertion depths and the amount of residual hearing preserved at 6 months post-operatively were compared between the two electrode groups. The median angular insertion depth for the HF1j was 439° and for the HFMS 435°. Preservation of residual hearing at 500 Hz was assessed in seven HFMS subjects and 11 HF1j subjects. Based on the Skarzynski formula, three out of seven subjects (42%) in the HFMS group had their residual hearing completely preserved at 500 Hz. In the control group, no subjects had complete hearing preservation and five subjects had a complete loss of residual hearing.

  1. Palladium nanoparticles decorated on reduced graphene oxide rotating disk electrodes toward ultrasensitive hydrazine detection: effects of particle size and hydrodynamic diffusion.

    Science.gov (United States)

    Krittayavathananon, Atiweena; Srimuk, Pattarachai; Luanwuthi, Santamon; Sawangphruk, Montree

    2014-12-16

    Although metal nanoparticle/graphene composites have been widely used as the electrode in electrochemical sensors, two effects, consisting of the particle size of the nanoparticles and the hydrodynamic diffusion of analytes to the electrodes, are not yet fully understood. In this work, palladium nanoparticles/reduced graphene oxide (PdNPs/rGO) composites were synthesized using an in situ polyol method. Palladium(II) ions and graphene oxide were reduced together with a reducing agent, ethylene glycol. By varying the concentration of palladium(II) nitrate, PdNPs with different sizes were decorated on the surface of rGO sheets. The as-fabricated PdNPs/rGO rotating disk electrodes (RDEs) were investigated toward hydrazine detection. Overall, a 3.7 ± 1.4 nm diameter PdNPs/rGO RDE exhibits high performance with a rather low limit of detection of about 7 nM at a rotation speed of 6000 rpm and provides a wide linear range of 0.1-1000 μM with R(2) = 0.995 at 2000 rpm. This electrode is highly selective to hydrazine without interference from uric acid, glucose, ammonia, caffeine, methylamine, ethylenediamine, hydroxylamine, n-butylamine, adenosine, cytosine, guanine, thymine, and l-arginine. The PdNPs/rGO RDEs with larger sizes show lower detection performance. Interestingly, the detection performance of the electrodes is sensitive to the hydrodynamic diffusion of hydrazine. The as-fabricated electrode can detect trace hydrazine in wastewater with high stability, demonstrating its practical use as an electrochemical sensor. These findings may lead to an awareness of the effect of the hydrodynamic diffusion of analyte that has been previously ignored, and the 3.7 ± 1.4 nm PdNPs/rGO RDE may be useful toward trace hydrazine detection, especially in wastewater from related chemical industries.

  2. Li diffusion in LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} thin film electrodes prepared by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xia Hui [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore); Lu Li [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore)], E-mail: mpeluli@nus.edu.sg; Lai, M.O. [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore)

    2009-10-30

    Kinetic and transport parameters of Li ion during its extraction/insertion into thin film LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} free of binder and conductive additive were provided in this work. LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} thin film electrodes were grown on Au substrates by pulsed laser deposition (PLD) and post-annealed. The annealed films exhibit a pure layered phase with a high degree of crystallinity. Surface morphology and thin film thickness were investigated by field emission scanning electron microscopy (FESEM). The charge/discharge behavior and rate capability of the thin film electrodes were investigated on Li/LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} cells at different current densities. The kinetics of Li diffusion in these thin film electrodes were investigated by cyclic voltammetry (CV) and galvanostatic intermittent titration technique (GITT). CV was measured between 2.5 and 4.5 V at different scan rates from 0.1 to 2 mV/s. The apparent chemical diffusion coefficients of Li in the thin film electrode were calculated to be 3.13 x 10{sup -13} cm{sup 2}/s for Li intercalation and 7.44 x 10{sup -14} cm{sup 2}/s for Li deintercalation. The chemical diffusion coefficients of Li in the thin film electrode were determined to be in the range of 10{sup -12}-10{sup -16} cm{sup 2}/s at different cell potentials by GITT. It is found that the Li diffusivity is highly dependent on the cell potential.

  3. Lateral gas phase diffusion length of boron atoms over Si/B surfaces during CVD of pure boron layers

    Energy Technology Data Exchange (ETDEWEB)

    Mohammadi, V., E-mail: V.Mohammadi@tudelft.nl; Nihtianov, S. [Department of Microelectronics, Delft University of Technology, Mekelweg 4, 2628 CD, Delft (Netherlands)

    2016-02-15

    The lateral gas phase diffusion length of boron atoms, L{sub B}, along silicon and boron surfaces during chemical vapor deposition (CVD) using diborane (B{sub 2}H{sub 6}) is reported. The value of L{sub B} is critical for reliable and uniform boron layer coverage. The presented information was obtained experimentally and confirmed analytically in the boron deposition temperature range from 700 °C down to 400 °C. For this temperature range the local loading effect of the boron deposition is investigated on the micro scale. A L{sub B} = 2.2 mm was determined for boron deposition at 700 °C, while a L{sub B} of less than 1 mm was observed at temperatures lower than 500 °C.

  4. Usefulness of diffusion tensor imaging in amyotrophic lateral sclerosis: potential biomarker and association with the cognitive profile

    Directory of Open Access Journals (Sweden)

    Marcelo Chaves

    Full Text Available ABSTRACT The objective of this preliminary study was to correlate diffusion tensor imaging (DTI alterations with the cognitive profile of patients with amyotrophic lateral sclerosis (ALS. Methods This was a case-control study conducted from December 1, 2012 to December 1, 2014. Clinical and demographic data were recorded. A neuropsychological test battery adapted to ALS patients was used. An MRI with DTI was performed in all patients and fractional anisotropy (FA was analyzed in the white matter using the tract based spatial statistics program. Results Twenty-four patients with ALS (15 females, mean age 66.9 + -2.3 and 13 healthy controls (four females, average age 66.9 + - 2 were included. The DTI showed white matter damage in ALS patients vs. healthy controls (p < 0.001. Discussion In our preliminary study the alterations of white matter in DTI were significantly associated with cognitive impairment in patients with ALS.

  5. Self-diffusion of electrolyte species in model battery electrodes using Magic Angle Spinning and Pulsed Field Gradient Nuclear Magnetic Resonance

    Science.gov (United States)

    Tambio, Sacris Jeru; Deschamps, Michaël; Sarou-Kanian, Vincent; Etiemble, Aurélien; Douillard, Thierry; Maire, Eric; Lestriez, Bernard

    2017-09-01

    Lithium-ion batteries are electrochemical storage devices using the electrochemical activity of the lithium ion in relation to intercalation compounds owing to mass transport phenomena through diffusion. Diffusion of the lithium ion in the electrode pores has been poorly understood due to the lack of experimental techniques for measuring its self-diffusion coefficient in porous media. Magic-Angle Spinning, Pulsed Field Gradient, Stimulated-Echo Nuclear Magnetic Resonance (MAS-PFG-STE NMR) was used here for the first time to measure the self-diffusion coefficients of the electrolyte species in the LP30 battery electrolyte (i.e. a 1 M solution of LiPF6 dissolved in 1:1 Ethylene Carbonate - Dimethyl Carbonate) in model composites. These composite electrodes were made of alumina, carbon black and PVdF-HFP. Alumina's magnetic susceptibility is close to the measured magnetic susceptibility of the LP30 electrolyte thereby limiting undesirable internal field gradients. Interestingly, the self-diffusion coefficient of lithium ions decreases with increasing carbon content. FIB-SEM was used to describe the 3D geometry of the samples. The comparison between the reduction of self-diffusion coefficients as measured by PFG-NMR and as geometrically derived from FIB/SEM tortuosity values highlights the contribution of specific interactions at the material/electrolyte interface on the lithium transport properties.

  6. On the modeling of electrical boundary layer (electrode layer) and derivation of atmospheric electrical profiles, eddy diffusion coeffcient and scales of electrode layer

    Indian Academy of Sciences (India)

    Madhuri N Kulkarni

    2010-02-01

    Electrode layer or electrical boundary layer is one of the charge generators in the global atmospheric electric circuit. In spite of this we find very few model studies and few measurements of it in the literature. Using a new technique it is shown that in this layer, the space charge density varies exponentially in vertical. A new experimental method based on the surface measurements is discussed to determine all the characteristic scales and an average electrical and meteorological state of an electrode layer. The results obtained are in good agreement with the previous studies. So, it is suggested that an exponential space charge density profile will no longer be an assumption in the case of electrode layer studies. The profiles of atmospheric electric field and electrical conductivity are also derived and a new term named as electrode layer constant is introduced.

  7. A finite element simulation on transient large deformation and mass diffusion in electrodes for lithium ion batteries

    Science.gov (United States)

    An, Yonghao; Jiang, Hanqing

    2013-10-01

    Lithium-ion batteries have attracted great deal of attention recently. Silicon is one of the most promising anode materials for high-performance lithium-ion batteries, due to its highest theoretical specific capacity. However, the short lifetime confined by mechanical failure in the silicon anode is now considered to be the biggest challenge in desired applications. High stress induced by the huge volume change due to lithium insertion/extraction is the main reason underlying this problem. Some theoretical models have been developed to address this issue. In order to properly implement these models, we develop a finite element based numerical method using a commercial software package, ABAQUS, as a platform at the continuum level to study fully coupled large deformation and mass diffusion problem. Using this method, large deformation, elasticity-plasticity of the electrodes, various spatial and temporal conditions, arbitrary geometry and dimension could be fulfilled. The interaction between anode and other components of the lithium ion batteries can also be studied as an integrated system. Several specific examples are presented to demonstrate the capability of this numerical platform.

  8. Manipulating the Lateral Diffusion of Surface-Anchored EGF Demonstrates that Receptor Clustering Modulates its Phosphorylation Levels

    Energy Technology Data Exchange (ETDEWEB)

    Stabley, Daniel [Emory University; Retterer, Scott T [ORNL; Marshal, Stephen [Emory University; Salaita, Khalid [Emory University

    2013-01-01

    Upon activation, the epidermal growth factor (EGF) receptor becomes phosphorylated and triggers a vast signaling network that has profound effects on cell growth. The EGF receptor is observed to assemble into clusters after ligand binding and tyrosine kinase autophosphorylation, but the role of these assemblies in the receptor signaling pathway remains unclear. To address this question, we measured the phosphorylation of EGFR when the EGF ligand was anchored onto laterally mobile and immobile surfaces. We found that cells generated clusters of ligand-receptor complex on mobile EGF surfaces, and generated a lower ratio of phosphorylated EGFR to EGF than when compared to immobilized EGF that is unable to cluster. This result was verified by tuning the lateral assembly of ligand-receptor complexes on the surface of living cells using patterned supported lipid bilayers. Nanoscale metal lines fabricated into the supported membrane constrained lipid diffusion and EGF receptor assembly into micron and sub-micron scale corrals. Single cell analysis indicated that clustering impacts EGF receptor activation, and larger clusters (> 1 m2) of ligand-receptor complex generated lower EGF receptor phosphorylation per ligand than smaller assemblies (< 1 m2) in HCC1143 cells that were engaged to ligand-functionalized surfaces. We investigated EGFR clustering by treating cells with compounds that disrupt the cytoskeleton (Latrunculin-B), clathrin-mediated endocytosis (Pitstop2), and inhibit EGFR activation (Gefitinib). These results help elucidate the nature of large-scale EGFR clustering, thus underscoring the general significance of receptor spatial organization in tuning function.

  9. TiO{sub 2} electrode with three-dimensional interweaved network structure for effective electrons transport and electrolyte diffusion in dye-sensitized solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jia [State Key Laboratory Of Alternate Electrical Power System With Renewable Energy Sources, Beijing Key Laboratory of Novel Thin Film Solar Cells, Renewable Energy School, North China Electric Power University, Beijing 102206 (China); Zhang, Bing; Xiao, Li; Liu, Xiu [Beijing Key Laboratory of Novel Thin Film Solar Cells, Renewable Energy School, North China Electric Power University, Beijing 102206 (China); Zhang, Yongzhe, E-mail: yzzhang@ncepu.edu.cn [Beijing Key Laboratory of Novel Thin Film Solar Cells, Renewable Energy School, North China Electric Power University, Beijing 102206 (China); Yao, Jianxi, E-mail: jianxiyao@ncepu.edu.cn [State Key Laboratory Of Alternate Electrical Power System With Renewable Energy Sources, Beijing Key Laboratory of Novel Thin Film Solar Cells, Renewable Energy School, North China Electric Power University, Beijing 102206 (China); Dai, Songyuan, E-mail: sydai@ncepu.edu.cn [Beijing Key Laboratory of Novel Thin Film Solar Cells, Renewable Energy School, North China Electric Power University, Beijing 102206 (China); Pan, Xu [Key Laboratory of Novel Thin Film Solar Cells, Institute of Plasma Physics, Chinese Academy of Science, Hefei 230031 (China)

    2015-03-25

    Highlights: • Photo polymerization induced phase separation method was used to prepare TiO{sub 2} films. • TiO{sub 2} films with three-dimensional network structure were used as photoanodes. • Energy conversion efficiency was enhanced compared to that of P25 film. • Both electrons transport and ions diffusion were promoted compared to P25 film. - Abstract: TiO{sub 2} electrodes with a three-dimensional interweaved network structure were fabricated on fluorine-doped tin oxide substrates for use in dye-sensitized solar cells. The structure was realized by photo-polymerization-induced phase separation. The electrodes had a continuous TiO{sub 2} skeleton and numerous interconnected macro/mesopores, which formed large three-dimensional cavity channels. The energy conversion efficiency of a dye-sensitized solar cell having the electrode was 3.01%, or 37.2% higher than that of a dye-sensitized solar cell having a P25 electrode with the same film thickness of 5 μm. The enhanced conversion efficiency can be attributed to improved electrons transport and I{sup −}/I{sub 3}{sup −} ion diffusion of photoanodes having interweaved network structure.

  10. Dimensionless numbers and correlating equations for the analysis of the membrane-gas diffusion electrode assembly in polymer electrolyte fuel cells

    Science.gov (United States)

    Gyenge, E. L.

    The Quraishi-Fahidy method [Can. J. Chem. Eng. 59 (1981) 563] was employed to derive characteristic dimensionless numbers for the membrane-electrolyte, cathode catalyst layer and gas diffuser, respectively, based on the model presented by Bernardi and Verbrugge for polymer electrolyte fuel cells [AIChE J. 37 (1991) 1151]. Monomial correlations among dimensionless numbers were developed and tested against experimental and mathematical modeling results. Dimensionless numbers comparing the bulk and surface-convective ionic conductivities, the electric and viscous forces and the current density and the fixed surface charges, were employed to describe the membrane ohmic drop and its non-linear dependence on current density due to membrane dehydration. The analysis of the catalyst layer yielded electrode kinetic equivalents of the second Damköhler number and Thiele modulus, influencing the penetration depth of the oxygen reduction front based on the pseudohomogeneous film model. The correlating equations for the catalyst layer could describe in a general analytical form, all the possible electrode polarization scenarios such as electrode kinetic control coupled or not with ionic and/or oxygen mass transport limitation. For the gas diffusion-backing layer correlations are presented in terms of the Nusselt number for mass transfer in electrochemical systems. The dimensionless number-based correlating equations for the membrane electrode assembly (MEA) could provide a practical approach to quantify single-cell polarization results obtained under a variety of experimental conditions and to implement them in models of the fuel cell stack.

  11. Morphology evolution via self-organization and lateral and vertical diffusion in polymer:fullerene solar cell blends.

    Science.gov (United States)

    Campoy-Quiles, Mariano; Ferenczi, Toby; Agostinelli, Tiziano; Etchegoin, Pablo G; Kim, Youngkyoo; Anthopoulos, Thomas D; Stavrinou, Paul N; Bradley, Donal D C; Nelson, Jenny

    2008-02-01

    Control of blend morphology at the microscopic scale is critical for optimizing the power conversion efficiency of plastic solar cells based on blends of conjugated polymer with fullerene derivatives. In the case of bulk heterojunctions of regioregular poly(3-hexylthiophene) (P3HT) and a soluble fullerene derivative ([6,6]-phenyl C61-butyric acid methyl ester, PCBM), both blend morphology and photovoltaic device performance are influenced by various treatments, including choice of solvent, rate of drying, thermal annealing and vapour annealing. Although the protocols differ significantly, the maximum power conversion efficiency values reported for the various techniques are comparable (4-5%). In this paper, we demonstrate that these techniques all lead to a common arrangement of the components, which consists of a vertically and laterally phase-separated blend of crystalline P3HT and PCBM. We propose a morphology evolution that consists of an initial crystallization of P3HT chains, followed by diffusion of PCBM molecules to nucleation sites, at which aggregates of PCBM then grow.

  12. A MoO2 sheet as a promising electrode material: ultrafast Li-diffusion and astonishing Li-storage capacity

    Science.gov (United States)

    Zhou, Yungang; Geng, Cheng

    2017-03-01

    The potential of MoO2 crystal as an electrode material is reported, and nanostructural MoO2 systems, including nanoparticles, nanospheres, nanobelts and nanowires, were synthesized and proved to be advanced electrode materials. A two-dimensional (2D) geometric structure represents an extreme of surface-to-volume ratio, and thus is more suitable as an electrode material in general. Stimulated by the recent fabrication of 2D MoO2, we adopted an ab initio molecular dynamics simulation and density functional theory calculation to study the stability and electrochemical properties of a MoO2 sheet. Identified by a phonon dispersion curve and potential energy curve calculations, the MoO2 sheet proved to be dynamically and thermally stable. After lithiation, similar to most promising 2D structures, we found that a Li atom can strongly adsorb on a MoO2 sheet, and the lithiated MoO2 sheet presented excellent metallic properties. Note that, compared with most promising 2D structures, we unexpectedly revealed that the diffusion barrier of the Li atom on the MoO2 sheet was much lower and the storage capacity of the MoO2 sheet was much larger. The calculated energy barrier for the diffusion of Li on the MoO2 sheet was only 75 meV, and, due to multilayer adsorption, the theoretical capacity of the MoO2 sheet can reach up to 2513 mA h g-1. Benefiting from general properties, such as strong Li-binding and excellent conductivity, and unique phenomena, such as ultrafast diffusion capacity and astonishing storage capacity, we highlight a new promising electrode material for the Li-ion battery.

  13. Gas diffusion electrodes for PEM-fuel cells via in situ-electrodeposition; Gasdiffusionselektroden fuer PEM-Brennstoffzellen durch in situ-Elektrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Vivien

    2009-03-16

    Commercial available membrane electrode assemblies are still very expensive, since a high noble metal catalyst loading has to be on the gas diffusion electrodes. The reason is particularly the fact that a high amount of the catalyst particles is not located in the so called three phase zone between ion conducting, electron conducting and reactant phase. In the present work the electrochemical synthesis of catalyst layers with a higher catalyst utilization, i. e. with a higher amount of particles located in the three phase zone has succeeded. Thus gas diffusion electrodes comparable in performance with commercial materials but coated with a lower catalyst loading were obtained. A second objective in this work was the development of an electrocombinatoric setup in which both the combinatoric electrosynthesis as well as the combinatoric analysis of platinum and platinum alloys can be performed. Furthermore different alloys were electrodeposited and electrocombinatorically analyzed with respect to their catalytic activity in the electroreduction of oxygen and the electrooxidation of hydrogen, methanol and ethanol. (orig.)

  14. Enhanced formation of >C1 products in the electroreduction of CO2 by adding a carbon dioxide adsorption component to a gas diffusion layer-type catalytic electrode.

    Science.gov (United States)

    Marepally, Bhanu Chandra; Ampelli, Claudio; Genovese, Chiara; Saboo, Tapish; Perathoner, Siglinda; Wisser, Florian M; Veyre, Laurent; Canivet, Jérôme; Quadrelli, Elsje Alessandra; Centi, Gabriele

    2017-09-18

    The addition of a CO2 adsorption component (substituted imidazolate-based SIM-1 crystals) to a gas diffusion layer (GDL) type catalytic electrode allows to enhance the activity and especially the selectivity to >C1 carbon chain products (ethanol, acetone and isopropanol) of a Pt-based electrocatalyst that is not able to form products of CO2 reduction involving C-C bond formation under conventional (liquid-phase) conditions. This indicates that the increase of the CO2 effective concentration at the electrode active surface is the factor controlling the formation of >C1 products rather than only the intrinsic properties of the electrocatalyst. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Measuring localization and diffusion coefficients of basolateral proteins in lateral versus basal membranes using functionalized substrates and kICS analysis

    DEFF Research Database (Denmark)

    Marlar, Saw; Christensen, Eva Arnspang; Pedersen, Gitte Albinus

    2014-01-01

    -cadherin and 0.037 ± 0.009 μm2/sec on collagen, thus, diffusion did not differ between substrates. Cholesterol depletion by methyl-beta-cyclodextrin (MBCD) reduced the AQP3-EGFP diffusion coefficient by 43 % from 0.024 ± 0.007 μm2/sec (water) to 0.014 ± 0.003 μm2/sec (MBCD) (p ...Micropatterning enabled semiquantitation of basolateral proteins in lateral and basal membranes of the same cell. Lateral diffusion coefficients of basolateral aquaporin-3 (AQP3-EGFP) and EGFP-AQP4 were extracted from “lateral” and “basal” membranes using identical live-cell imaging and k...... principal cells AQP3 localize lateral and basal whereas AQP4 localize mainly basal. On alternating stripes of E-cadherin and collagen, AQP3-EGFP was predominantly localized to “lateral” compared to “basal” membranes, whereas Orange-AQP4 was evenly distributed. Average diffusion coefficients were extracted...

  16. Influence of the oxygen electrode and inter-diffusion barrier on the degradation of solid oxide electrolysis cells

    DEFF Research Database (Denmark)

    Hjalmarsson, Per; Sun, Xiufu; Liu, Yi-Lin

    2013-01-01

    Two Solid Oxide Electrolysis Cells (SOECs) with different oxygen electrodes have been tested in galvanostatic tests carried out at −1.5 Acm−2 and 800 °C converting 60% of a 50:50% mixture of H2O and CO2 (co-electrolysis). One of the cells had an LSM:YSZ oxygen electrode. The other had an CGO inte...

  17. Multi-electrode laterally coupled distributed feedback InGaAsP/InP lasers: a prescription for longitudinal mode control

    Science.gov (United States)

    Benhsaien, Abdessamad; Dridi, Kais; Zhang, Jessica; Hall, Trevor J.

    2013-10-01

    Photonic Integrated Circuits (PICs) enable photons as data carriers at a very high speed. PIC market opportunities call for reduced wafer dimensions, power consumption and cost as well as enhanced reliability. The PIC technology development must cater for the latter relentless traits. In particular, monolithic PICs are sought as they can integrate hundreds of components and functions onto a single chip. InGaAsP/InP laterally-coupled distributed feedback (LC-DFB) lasers stand as key enablers in the PIC technology thanks to the compelling advantages their embedded high-order surface-gratings have. The patterning of the spatial corrugation along the sidewalls of the LC-DFB ridge, has been established to make the epitaxial overgrowth unnecessary thereby reducing the cost and time of manufacturing, and ultimately increasing the yield. LC-DFBs boast a small footprint synonymous of enhanced monolithic integrate-ability. Nonetheless, LC-DFBs suffer from the adverse longitudinal spatial hole burning (LSHB) effects materialized by typically quite high threshold current levels. Indeed, the carrier density longitudinal gradient- responsible for modes contending for the available material gain in the cavity- may be alleviated somewhat by segmenting the LC-DFB electrode into two or three reasonably interspaced longitudinal sections. In this work we report on the realization and performance of various electrode partition configurations. At room temperature, the experimental characterization of many as-cleaved LC-DFB devices provides ample evidence of superior performance such as a narrow linewidth (less than 400 kHz), a wide wavelength tune-ability (over 4 nm) and a hop-free single mode emission (side mode suppression ratio (SMSR) exceeding 54dB).

  18. Assessing lateral flows and solute transport during floods in a conduit-flow-dominated karst system using the inverse problem for the advection–diffusion equation

    Directory of Open Access Journals (Sweden)

    C. Cholet

    2017-07-01

    Full Text Available The aim of this study is to present a framework that provides new ways to characterize the spatio-temporal variability of lateral exchanges for water flow and solute transport in a karst conduit network during flood events, treating both the diffusive wave equation and the advection–diffusion equation with the same mathematical approach, assuming uniform lateral flow and solute transport. A solution to the inverse problem for the advection–diffusion equations is then applied to data from two successive gauging stations to simulate flows and solute exchange dynamics after recharge. The study site is the karst conduit network of the Fourbanne aquifer in the French Jura Mountains, which includes two reaches characterizing the network from sinkhole to cave stream to the spring. The model is applied, after separation of the base from the flood components, on discharge and total dissolved solids (TDSs in order to assess lateral flows and solute concentrations and compare them to help identify water origin. The results showed various lateral contributions in space – between the two reaches located in the unsaturated zone (R1, and in the zone that is both unsaturated and saturated (R2 – as well as in time, according to hydrological conditions. Globally, the two reaches show a distinct response to flood routing, with important lateral inflows on R1 and large outflows on R2. By combining these results with solute exchanges and the analysis of flood routing parameters distribution, we showed that lateral inflows on R1 are the addition of diffuse infiltration (observed whatever the hydrological conditions and localized infiltration in the secondary conduit network (tributaries in the unsaturated zone, except in extreme dry periods. On R2, despite inflows on the base component, lateral outflows are observed during floods. This pattern was attributed to the concept of reversal flows of conduit–matrix exchanges, inducing a complex water mixing effect

  19. Assessing lateral flows and solute transport during floods in a conduit-flow-dominated karst system using the inverse problem for the advection-diffusion equation

    Science.gov (United States)

    Cholet, Cybèle; Charlier, Jean-Baptiste; Moussa, Roger; Steinmann, Marc; Denimal, Sophie

    2017-07-01

    The aim of this study is to present a framework that provides new ways to characterize the spatio-temporal variability of lateral exchanges for water flow and solute transport in a karst conduit network during flood events, treating both the diffusive wave equation and the advection-diffusion equation with the same mathematical approach, assuming uniform lateral flow and solute transport. A solution to the inverse problem for the advection-diffusion equations is then applied to data from two successive gauging stations to simulate flows and solute exchange dynamics after recharge. The study site is the karst conduit network of the Fourbanne aquifer in the French Jura Mountains, which includes two reaches characterizing the network from sinkhole to cave stream to the spring. The model is applied, after separation of the base from the flood components, on discharge and total dissolved solids (TDSs) in order to assess lateral flows and solute concentrations and compare them to help identify water origin. The results showed various lateral contributions in space - between the two reaches located in the unsaturated zone (R1), and in the zone that is both unsaturated and saturated (R2) - as well as in time, according to hydrological conditions. Globally, the two reaches show a distinct response to flood routing, with important lateral inflows on R1 and large outflows on R2. By combining these results with solute exchanges and the analysis of flood routing parameters distribution, we showed that lateral inflows on R1 are the addition of diffuse infiltration (observed whatever the hydrological conditions) and localized infiltration in the secondary conduit network (tributaries) in the unsaturated zone, except in extreme dry periods. On R2, despite inflows on the base component, lateral outflows are observed during floods. This pattern was attributed to the concept of reversal flows of conduit-matrix exchanges, inducing a complex water mixing effect in the saturated zone

  20. Effects of approach and injection volume on diffusion of mepivacaine hydrochloride during local analgesia of the deep branch of the lateral plantar nerve in horses.

    Science.gov (United States)

    Claunch, Kevin M; Eggleston, Randy B; Baxter, Gary M

    2014-11-15

    To compare the effects of 2 approaches and 2 injection volumes on diffusion of mepivacaine hydrochloride for local analgesia of the deep branch of the lateral plantar nerve (DBLPN) in horses. Experimental study. 16 adult horses. Either 2 mL (low volume) or 8 mL (high volume) of mepivacaine hydrochloride-iohexol (50:50 mixture) was injected by means of 1 of 2 techniques to produce analgesia of the DBLPN. For technique 1, the needle was inserted 15 mm distal to the head of the fourth metatarsal bone and directed perpendicular to the limb. For technique 2, the needle was inserted 20 mm distal to the head of the fourth metatarsal bone and was directed in a proximodorsal direction. Lateromedial radiographs were obtained before and 5, 15, 30, and 60 minutes after injection. Radiographs were evaluated to determine the proximal and distal extent of diffusion of the contrast solution and presumably anesthetic agent and whether contrast agent appeared to be present in the tarsal sheath or tarsometatarsal joint. A high degree of variability in contrast solution diffusion was noted among injections. High-volume injections diffused significantly further proximally and distally than did low-volume injections. Contrast agent was documented within the tarsal sheath in 5 of 32 (16%) injections and within the tarsometatarsal joint in 2 of 32 (6%) injections. No significant difference was found for risk of inadvertent tarsal sheath or tarsometatarsal joint injection between the 2 techniques or the 2 volumes of anesthetic used. Mepivacaine diffused significantly further distally with technique 1 than with technique 2 but diffused significantly further proximally with technique 2 than with technique 1. For both techniques, diffusion in the distal but not the proximal direction significantly increased over time. Results indicated that the proximal and distal diffusion of the mepivacaine-iohexol solution was quite variable following either DBLPN nerve block technique.

  1. Insight into the electroreduction of nitrate ions at a copper electrode, in neutral solution, after determination of their diffusion coefficient by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Aouina, Nizar; Cachet, Hubert [Laboratoire Interfaces et Systemes Electrochimiques - UPR15 du CNRS, Universite Pierre et Marie Curie - Paris 6, 4, place Jussieu, F-75005 Paris (France); Debiemme-chouvy, Catherine, E-mail: catherine.debiemme-chouvy@upmc.f [Laboratoire Interfaces et Systemes Electrochimiques - UPR15 du CNRS, Universite Pierre et Marie Curie - Paris 6, 4, place Jussieu, F-75005 Paris (France); Tran, Thi Tuyet Mai [Laboratoire Interfaces et Systemes Electrochimiques - UPR15 du CNRS, Universite Pierre et Marie Curie - Paris 6, 4, place Jussieu, F-75005 Paris (France)

    2010-10-01

    The electrochemical reduction of nitrate ions at a copper electrode in an unbuffered neutral aqueous solution is studied. Using a two compartment electrochemical cell, three stationary cathodic waves, noted P1, P2 and P3, were evidenced by cyclic voltammetry at -0.9, -1.2 and -1.3 V/SCE, respectively. By comparing the electrochemical response of nitrate and nitrite containing solutions, P1 was attributed to the reduction of nitrate to nitrite. In order to assign P2 and P3 features by determining the number of electrons involved at the corresponding potential, rotating disk electrode experiments at various rotation speeds, combined with linear sweep voltammetry, were performed. Current data analysis at a given potential was carried out using Koutecky-Levich treatment taking into account water reduction. Confident values of the diffusion coefficient D of nitrate ions were assessed by electrochemical impedance spectroscopy for nitrate concentrations of 10{sup -3}, 10{sup -2} and 10{sup -1} M. For a nitrate concentration of 10{sup -2} M, D was found to be 1.31 x 10{sup -5} cm{sup 2} s{sup -1} allowing the number of electrons to be determined as 6 for P2 and 8 for P3, in accordance with nitrate reduction into hydroxylamine and ammonia, respectively. The formation of hydroxylamine was confirmed by the observation of its reoxidation at a Pt microelectrode present at the Cu electrode/nitrate solution interface.

  2. Anomalous output characteristic shift for the n-type lateral diffused metal-oxide-semiconductor transistor with floating P-top layer

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Siyang; Zhang, Chunwei; Sun, Weifeng, E-mail: swffrog@seu.edu.cn [National ASIC System Engineering Research Center, Southeast University, Nanjing 210096 (China); Su, Wei; Wang, Shaorong; Ma, Shulang; Huang, Yu [CSMC Technologies Corporation, Wuxi 214061 (China)

    2014-04-14

    Anomalous output characteristic shift of the n-type lateral diffused metal-oxide-semiconductor transistor with floating P-top layer is investigated. It shows that the linear drain current has obvious decrease when the output characteristic of fresh device is measured for two consecutive times. The charge pumping experiments demonstrate that the decrease is not from hot-carrier degradation. The reduction of cross section area for the current flowing, which results from the squeezing of the depletion region surrounding the P-top layer, is responsible for the shift. Consequently, the current capability of this special device should be evaluated by the second measured output characteristic.

  3. Language Laterality in Autism Spectrum Disorder and Typical Controls: A Functional, Volumetric, and Diffusion Tensor MRI Study

    Science.gov (United States)

    Knaus, Tracey A.; Silver, Andrew M.; Kennedy, Meaghan; Lindgren, Kristen A.; Dominick, Kelli C.; Siegel, Jeremy; Tager-Flusberg, Helen

    2010-01-01

    Language and communication deficits are among the core features of autism spectrum disorder (ASD). Reduced or reversed asymmetry of language has been found in a number of disorders, including ASD. Studies of healthy adults have found an association between language laterality and anatomical measures but this has not been systematically…

  4. A Novel Super-Junction Lateral Double-Diffused Metal-Oxide-Semiconductor Field Effect Transistor with n-Type Step Doping Buffer Layer

    Institute of Scientific and Technical Information of China (English)

    CHENG Jian-Bing; ZHANG Do; DUAN Bao-Xing; LI Zhao-Ji

    2008-01-01

    A novel super-junction lateral double-diffused metal-nxide-semiconductor field effect transistor(SJ-LDMOSFET)with n-type step doping buffer layer is proposed.The step doping buffer layer almost completely eliminates the substrate-assisted depletion effect.modulates lateral electric field and achieves nearly uniform surface field.On the other hand,the buffer layer also provides another conductive path and reduces on-state resistance.In short,the proposed LDMOSFET improves trade-off performance between breakdown voltage (BV)and specific on-state resistance Ron,sp.Compared with the conventional SJ-LDMOSFET,the simulation results indicate that the BV of the SSJ-LDMOSFET is increased from saturation voltage 121.7 V to 644.9 V;at the same time,the specific when the drift region length and the step number are taken as 48μm and 3,respectively.

  5. Reduced structural integrity and functional lateralization of the dorsal language pathway correlate with hallucinations in schizophrenia: a combined diffusion spectrum imaging and functional magnetic resonance imaging study.

    Science.gov (United States)

    Wu, Chen-Hao; Hwang, Tzung-Jeng; Chen, Pin-Jane; Chou, Tai-Li; Hsu, Yung-Chin; Liu, Chih-Min; Wang, Hsiao-Lan; Chen, Chung-Ming; Hua, Mau-Sun; Hwu, Hai-Gwo; Tseng, Wen-Yih Isaac

    2014-12-30

    Recent studies suggest that structural and functional alterations of the language network are associated with auditory verbal hallucinations (AVHs) in schizophrenia. However, the ways in which the underlying structure and function of the network are altered and how these alterations are related to each other remain unclear. To elucidate this, we used diffusion spectrum imaging (DSI) to reconstruct the dorsal and ventral pathways and employed functional magnetic resonance imaging (fMRI) in a semantic task to obtain information about the functional activation in the corresponding regions in 18 patients with schizophrenia and 18 matched controls. The results demonstrated decreased structural integrity in the left ventral, right ventral and right dorsal tracts, and decreased functional lateralization of the dorsal pathway in schizophrenia. There was a positive correlation between the microstructural integrity of the right dorsal pathway and the functional lateralization of the dorsal pathway in patients with schizophrenia. Additionally, both functional lateralization of the dorsal pathway and microstructural integrity of the right dorsal pathway were negatively correlated with the scores of the delusion/hallucination symptom dimension. Our results suggest that impaired structural integrity of the right dorsal pathway is related to the reduction of functional lateralization of the dorsal pathway, and these alterations may aggravate AVHs in schizophrenia. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  6. Optical detection of ion diffusion in electrochromic poly(3,4-ethylenedioxy)thiophene film using microcantilever electrodes

    DEFF Research Database (Denmark)

    Lin, Rong; Stokbro, Kurt; Madsen, Dorte Nørgaard;

    2005-01-01

    potential of the film induced dark (light-absorbing) rings, which spread out from the anode on a time scale of seconds. The rate of expansion of the rings as well as the final diameter depended on the bias voltage. Using two micro four-point probes simultaneously, we measured with one probe the conductance......We present measurements of microscale electrochromic switching of poly(3,4-ethylenedioxy)thiophene doped with poly(4-styrene sulfonate), thin film using microfabricated multi-point probe electrodes. After treatment with a dilute hydrochloric acid, a voltage bias above 3 V with respect to the ground...... of the film outside, near and inside a dark ring induced by a voltage applied to another probe and found the resistivity to be directly related to the observed absorbance of the film. The standard electrochromic mechanism of ion insertion was used to explain the observations. We anticipate this experimental...

  7. Diffuse traumatic brain injury initially attenuates and later expands activation of the rat somatosensory whisker circuit concomitant with neuroplastic responses.

    Science.gov (United States)

    Hall, Kelley D; Lifshitz, Jonathan

    2010-04-06

    Traumatic brain injury can initiate an array of chronic neurological deficits, effecting executive function, language and sensorimotor integration. Mechanical forces produce the diffuse pathology that disrupts neural circuit activation across vulnerable brain regions. The present manuscript explores the hypothesis that the extent of functional activation of brain-injured circuits is a consequence of initial disruption and consequent reorganization. In the rat, enduring sensory sensitivity to whisker stimulation directs regional analysis to the whisker barrel circuit. Adult, male rats were subjected to midline fluid percussion brain or sham injury and evaluated between 1day and 42days post-injury. Whisker somatosensory regions of the cortex and thalamus maintained cellular composition as visualized by Nissl stain. Within the first week post-injury, quantitatively less cFos activation was elicited by whisker stimulation, potentially due to axotomy within and surrounding the whisker circuit as visualized by amyloid precursor protein immunohistochemistry. Over six weeks post-injury, cFos activation after whisker stimulation showed a significant linear correlation with time in the cortex (r(2)=0.545; p=0.015), non-significant correlation in the thalamus (r(2)=0.326) and U-shaped correlation in the dentate gyrus (r(2)=0.831), all eventually exceeding sham levels. Ongoing neuroplastic responses in the cortex are evidenced by accumulating growth associated protein and synaptophysin gene expression. In the thalamus, the delayed restoration of plasticity markers may explain the broad distribution of neuronal activation extending into the striatum and hippocampus with whisker stimulation. The sprouting of diffuse-injured circuits into diffuse-injured tissue likely establishes maladaptive circuits responsible for behavioral morbidity. Therapeutic interventions to promote adaptive circuit restructuring may mitigate post-traumatic morbidity. Copyright 2010 Elsevier B.V. All

  8. Use of Diffusion Spectrum imaging in preliminary longitudinal evaluation of Amyotrophic Lateral Sclerosis: development of an imaging biomarker

    Directory of Open Access Journals (Sweden)

    Kumar eAbhinav

    2014-04-01

    Full Text Available Previous diffusion tensor imaging (DTI studies have shown white matter pathology in ALS, predominantly in the motor pathways. Further these studies have shown that DTI can be used longitudinally to track pathology over time, making white matter pathology a candidate as an outcome measure in future trials. DTI has demonstrated application in group studies, however its derived indices, for example fractional anisotropy, are susceptible to partial volume effects, making its role questionable in examining individual progression. We hypothesize that changes in the white matter are present in ALS beyond the motor tracts, and that the affected pathways and associated pattern of disease progression can be tracked longitudinally using automated diffusion connectometry analysis. Connectometry analysis is based on diffusion spectrum imaging (DSI and overcomes the limitations of a conventional tractography approach and DTI. The identified affected white matter tracts can then be assessed in a targeted fashion using High definition fiber tractography (a novel white matter MR imaging technique. Changes in quantitative and qualitative markers over time could then be correlated with clinical progression.We illustrate these principles towards developing an imaging biomarker for demonstrating individual progression, by presenting results for five ALS patients, including with longitudinal data in two. Preliminary analysis demonstrated a number of changes bilaterally and asymmetrically in motoric and extramotoric white matter pathways. Further the limbic system was also affected possibly explaining the cognitive symptoms in ALS. In the two longitudinal subjects, the white matter changes were less extensive at baseline, although there was evidence of disease progression in a frontal pattern with a relatively spared postcentral gyrus, consistent with the known pathology in ALS.

  9. Reduced Integrity of Right Lateralized White Matter in Patients with Primary Insomnia: A Diffusion-Tensor Imaging Study.

    Science.gov (United States)

    Li, Shumei; Tian, Junzhang; Bauer, Andreas; Huang, Ruiwang; Wen, Hua; Li, Meng; Wang, Tianyue; Xia, Likun; Jiang, Guihua

    2016-08-01

    Purpose To analyze the integrity of white matter (WM) tracts in primary insomnia patients and provide better characterization of abnormal WM integrity and its relationship with disease duration and clinical features of primary insomnia. Materials and Methods This prospective study was approved by the ethics committee of the Guangdong No. 2 Provincial People's Hospital. Tract-based spatial statistics were used to compare changes in diffusion parameters of WM tracts from 23 primary insomnia patients and 30 healthy control (HC) participants, and the accuracy of these changes in distinguishing insomnia patients from HC participants was evaluated. Voxel-wise statistics across subjects was performed by using a 5000-permutation set with family-wise error correction (family-wise error, P right anterior limb of the internal capsule, right posterior limb of the internal capsule, right anterior corona radiata, right superior corona radiata, right superior longitudinal fasciculus, body of the corpus callosum, and right thalamus (P family-wise error correction). The receiver operating characteristic areas for the seven regions were acceptable (range, 0.60-0.74; 60%-74%). Multiple regression models showed abnormal FA values in the thalamus and body corpus callosum were associated with the disease duration, self-rating depression scale, and Pittsburgh Sleep Quality Index scores. Tract-level analysis suggested that the reduced FA values might be related to greater radial diffusivity. Conclusion This study showed that WM tracts related to regulation of sleep and wakefulness, and limbic cognitive and sensorimotor regions, are disrupted in the right brain in patients with primary insomnia. The reduced integrity of these WM tracts may be because of loss of myelination. (©) RSNA, 2016.

  10. Modulation of manual preference induced by lateralized practice diffuses over distinct motor tasks: age-related effects.

    Science.gov (United States)

    Souza, Rosana M; Coelho, Daniel B; Teixeira, Luis A

    2014-01-01

    In this study we investigated the effect of use of the non-preferred left hand to practice different motor tasks on manual preference in children and adults. Manual preference was evaluated before, immediately after and 20 days following practice. Evaluation was made with tasks of distinct levels of complexity requiring reaching and manipulation of cards at different eccentricities in the workspace. Results showed that left hand use in adults induced increased preference of that hand at the central position when performing the simple task, while left hand use by the children induced increased preference of the left hand at the rightmost positions in the performance of the complex task. These effects were retained over the rest period following practice. Kinematic analysis showed that left hand use during practice did not lead to modification of intermanual performance asymmetry. These results indicate that modulation of manual preference was a consequence of higher frequency of use of the left hand during practice rather than of change in motor performance. Findings presented here support the conceptualization that confidence on successful performance when using a particular limb generates a bias in hand selection, which diffuses over distinct motor tasks.

  11. Modulation of manual preference induced by lateralized practice diffuses over distinct motor tasks: age-related effects

    Directory of Open Access Journals (Sweden)

    Rosana Machado de Souza

    2014-12-01

    Full Text Available In this study we investigated the effect of use of the nonpreferred left hand to practice different motor tasks on manual preference in children and adults. Manual preference was evaluated before, immediately after and 20 days following practice. Evaluation was made with tasks of distinct levels of complexity requiring reaching and manipulation of cards at different eccentricities in the workspace. Results showed that left hand use in adults induced increased preference of that hand at the central position when performing the simple task, while left hand use by the children induced increased preference of the left hand at the rightmost positions in the performance of the complex task. These effects were retained over the rest period following practice. Kinematic analysis showed that left hand use during practice did not lead to modification of intermanual performance asymmetry. These results indicate that modulation of manual preference was a consequence of higher frequency of use of the left hand during practice rather than of change in motor performance. Findings presented here support the conceptualization that confidence on successful performance when using a particular limb generates a bias in hand selection, which diffuses over distinct motor tasks.

  12. Influence of charged microenvironment on redox potential and diffusion coefficient of [Fe4S4(SPh)4](NBu4)2 in DMF and inside CTAB film on electrode surface

    Indian Academy of Sciences (India)

    Raben Ch Roy; Diganta Kumar Das

    2005-11-01

    Redox potential of [Fe4S4(SPh)4]2-/3-, a model of the active centre of ferredoxin, in DMF solution shows a 90-mV positive shift, when the charged microenvironment provided by the surfactant is changed from negative to positive. Inside the positive surfactant film on GC electrode there is a 235-mV positive shift in redox potential compared to that in neutral DMF solution. Diffusion coefficient of the reduced cluster onto the electrode surface is also found to be 102 times greater in the presence of negative surfactant compared to that in positive surfactant.

  13. Relationship between phosphatidylinositol 4-phosphate synthesis, membrane organization, and lateral diffusion of PI4KIIalpha at the trans-Golgi network.

    Science.gov (United States)

    Minogue, Shane; Chu, K M Emily; Westover, Emily J; Covey, Douglas F; Hsuan, J Justin; Waugh, Mark G

    2010-08-01

    Type II phosphatidylinositol 4-kinase IIalpha (PI4KIIalpha) is the dominant phosphatidylinositol kinase activity measured in mammalian cells and has important functions in intracellular vesicular trafficking. Recently PI4KIIalpha has been shown to have important roles in neuronal survival and tumorigenesis. This study focuses on the relationship between membrane cholesterol levels, phosphatidylinositol 4-phosphate (PI4P) synthesis, and PI4KIIalpha mobility. Enzyme kinetic measurements, sterol substitution studies, and membrane fragmentation analyses all revealed that cholesterol regulates PI4KIIalpha activity indirectly through effects on membrane structure. In particular, we found that cholesterol levels determined the distribution of PI4KIIalpha to biophysically distinct membrane domains. Imaging studies on cells expressing enhanced green fluorescent protein (eGFP)-tagged PI4KIIalpha demonstrated that cholesterol depletion resulted in morphological changes to the juxtanuclear membrane pool of the enzyme. Lateral membrane diffusion of eGFP-PI4KIIalpha was assessed by fluorescence recovery after photobleaching (FRAP) experiments, which revealed the existence of both mobile and immobile pools of the enzyme. Sterol depletion decreased the size of the mobile pool of PI4KIIalpha. Further measurements revealed that the reduction in the mobile fraction of PI4KIIalpha correlated with a loss of trans-Golgi network (TGN) membrane connectivity. We conclude that cholesterol modulates PI4P synthesis through effects on membrane organization and enzyme diffusion.

  14. In vivo diffusion characteristics following perineural injection of the deep branch of the lateral plantar nerve with mepivacaine or iohexol in horses.

    Science.gov (United States)

    Contino, E K; King, M R; Valdés-Martínez, A; McIlwraith, C W

    2015-03-01

    Hindlimb proximal suspensory desmopathy is a common injury of sport horses but diagnosis can be difficult because diagnostic analgesia of the region lacks specificity. Perineural analgesia of the deep branch of the lateral plantar nerve (DBLPN) has been proposed as a more specific method of isolating pain of the proximal aspect of the suspensory ligament but the technique has not been evaluated in vivo. To determine the extent of diffusion of contrast medium and mepivacaine following DBLPN analgesia using a single-needle injection technique and to determine if there is inadvertent involvement of the tarsal sheath and/or tarsometatarsal (TMT) joint using this technique. In vivo experimental study. Perineural injection of the DBLPN was performed in 16 limbs with 3 ml of either mepivacaine hydrochloride or positive contrast medium. Contrast medium-injected limbs were radiographed 5, 15, and 30 min post injection and diffusion characteristics were described. In mepivacaine-injected limbs, synovial fluid from the TMT joint was obtained 10 and 20 min post injection and mepivacaine concentrations were analysed. At 5, 15 and 30 min post injection, the contrast medium extended, on average, 19.6, 20.6 and 21.0 mm proximal and 38.0, 43.5 and 51.9 mm distal to the injection site, respectively. Three of 8 (37.5%) limbs had evidence of contrast medium in the tarsal sheath. Two of 8 (25%) limbs had mepivacaine concentrations within the TMT joint sufficient to produce analgesia (>300 mg/l) at 10 min post injection. Contrast medium diffused further in a distal direction than in a proximal direction. Analgesia of the DBLPN can result in inadvertent involvement of the tarsal sheath and/or TMT joint. © 2014 EVJ Ltd.

  15. An assembled poly-4-vinyl pyridine and cellulose triacetate membrane and Bi2S3 electrode for photoelectrochemical diffusion of metallic ions.

    Science.gov (United States)

    Amara, Mourad; Arous, Omar; Smail, Fatima; Kerdjoudj, Hacène; Trari, Mohamed; Bouguelia, Aissa

    2009-09-30

    The transport phenomena across ion exchange membrane may be enhanced by applying various strengths inside or outside the system. The electrical current, generated by n-type semiconductor, is used to catalyse the separation of metal ions. The cation exchange membrane located between the two compartments allows both the separation and concentration of M(n+) (Ag(+), Cu(2+), Pb(2+) and Ni(2+)). The flows of M(n+) from the aqueous solution to-and inside the membrane are monitored by the determination of the fluxes and the potentials. In this study, the four cations are investigated alone or in quaternary systems. From photoelectrochemical measurement, the gap of Bi(2)S(3) is found to be indirect at 1.65 eV. The shape of photocurrent potential curve and the negative flat band potential (-1.02 V(SCE)) give evidence of n-type character. The conduction band (-1.25 V(SCE)) yields thermodynamically M(2+) photoreduction and catalyzes the diffusion process. The photoelectrode Bi(2)S(3) makes the flux twofold greater than that observed in the dark. In all cases, the potential of the electrode M(2+)/M in the feed compartment increases until a maximal value, reached at approximately 100 min above which it undergoes a diminution. The membrane is more selective to Cu(2+) and this selectivity decreases in the quaternary system.

  16. The back-diffusion effect of air on the discharge characteristics of atmospheric-pressure radio-frequency glow discharges using bare metal electrodes

    Science.gov (United States)

    Sun, Wen-Ting; Liang, Tian-Ran; Wang, Hua-Bo; Li, He-Ping; Bao, Cheng-Yu

    2007-05-01

    Radio-frequency (RF), atmospheric-pressure glow discharge (APGD) plasmas using bare metal electrodes have promising prospects in the fields of plasma-aided etching, deposition, surface treatment, disinfection, sterilization, etc. In this paper, the discharge characteristics, including the breakdown voltage and the discharge voltage for sustaining a stable and uniform α mode discharge of the RF APGD plasmas are presented. The experiments are conducted by placing the home-made planar-type plasma generator in ambient and in a vacuum chamber, respectively, with helium as the primary plasma-forming gas. When the discharge processes occur in ambient, particularly for the lower plasma-working gas flow rates, the experimental measurements show that it is the back-diffusion effect of air in atmosphere, instead of the flow rate of the gas, that results in the obvious decrease in the breakdown voltage with increasing plasma-working gas flow rate. Further studies on the discharge characteristics, e.g. the luminous structures, the concentrations and distributions of chemically active species in plasmas, with different plasma-working gases or gas mixtures need to be conducted in future work.

  17. The back-diffusion effect of air on the discharge characteristics of atmospheric-pressure radio-frequency glow discharges using bare metal electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Sun Wenting; Liang Tianran; Wang Huabo; Li Heping; Bao Chengyu [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

    2007-05-15

    Radio-frequency (RF), atmospheric-pressure glow discharge (APGD) plasmas using bare metal electrodes have promising prospects in the fields of plasma-aided etching, deposition, surface treatment, disinfection, sterilization, etc. In this paper, the discharge characteristics, including the breakdown voltage and the discharge voltage for sustaining a stable and uniform {alpha} mode discharge of the RF APGD plasmas are presented. The experiments are conducted by placing the home-made planar-type plasma generator in ambient and in a vacuum chamber, respectively, with helium as the primary plasma-forming gas. When the discharge processes occur in ambient, particularly for the lower plasma-working gas flow rates, the experimental measurements show that it is the back-diffusion effect of air in atmosphere, instead of the flow rate of the gas, that results in the obvious decrease in the breakdown voltage with increasing plasma-working gas flow rate. Further studies on the discharge characteristics, e.g. the luminous structures, the concentrations and distributions of chemically active species in plasmas, with different plasma-working gases or gas mixtures need to be conducted in future work.

  18. Voltammetry at porous electrodes: A theoretical study

    CERN Document Server

    Barnes, Edward O; Li, Peilin; Compton, Richard G

    2014-01-01

    Theory is presented to simulate both chronoamperometry and cyclic voltammetry at porous electrodes fabricated by means of electro-deposition around spherical templates. A theoretical method to extract heterogeneous rate constants for quasireversible and irreversible systems is proposed by the approximation of decoupling of the diffusion within the porous electrode and of bulk diffusion to the electrode surface.

  19. Influence of the long-chain/short-chain amphiphile ratio on lateral diffusion of PEG-lipid in magnetically aligned lipid bilayers as measured via pulsed-field-gradient NMR.

    Science.gov (United States)

    Soong, Ronald; Macdonald, Peter M

    2005-09-01

    Lateral diffusion measurements of polyethylene glycol(PEG)-lipid incorporated into magnetically aligned lipid bilayers, composed of dimyristoyl phosphatidylcholine (DMPC) plus dihexanoyl phosphatidylcholine (DHPC) plus 1 mol % (relative to DMPC) dimyristoyl phosphatidylethanolamine-n-[methoxy(polyethylene glycol)-2000] (DMPE-PEG 2000), were performed using stimulated-echo pulsed-field-gradient proton ((1)H) nuclear magnetic resonance spectroscopy. The DMPE-PEG 2000 (1 mol %, 35 degrees C) lateral diffusion coefficient D varied directly with the mole fraction of DMPC, X(DMPC) = q/(1+q) where q = DMPC/DHPC molar ratio, decreasing progressively from D = 1.65 x 10(-11) m(2) s(-1) at q approximately 4.7 to D = 0.65 x 10(-11) m(2) s(-1) at q approximately 2.5. Possible sources of this dependence, including orientational disorder, obstruction, and PEG-lipid sequestration, were simulated using, respectively, a diffusion-in-a-cone model, percolation theory, and a two-phase PEG distribution model. Orientational disorder alone was not capable of reproducing the observations, but in combination with either obstruction or PEG-lipid two-phase distribution models did so satisfactorily. A combination of all three models yielded the most reasonable fit to the observed dependence of lateral diffusion on q. These same effects would be expected to influence lateral diffusion of any bilayer-associating species in such systems.

  20. An assembled poly-4-vinyl pyridine and cellulose triacetate membrane and Bi{sub 2}S{sub 3} electrode for photoelectrochemical diffusion of metallic ions

    Energy Technology Data Exchange (ETDEWEB)

    Amara, Mourad [Laboratory of Hydrometallurgy and Molecular Inorganic Chemistry Faculty of Chemistry, USTHB, BP 32, El Alia, 16111, Algiers (Algeria); Arous, Omar [Laboratory of Hydrometallurgy and Molecular Inorganic Chemistry Faculty of Chemistry, USTHB, BP 32, El Alia, 16111, Algiers (Algeria); Centre of Research in Physical and Chemical Analysis CRAPC, PO BOX 248 Algiers RP 16004, Algiers (Algeria); Smail, Fatima; Kerdjoudj, Hacene [Laboratory of Hydrometallurgy and Molecular Inorganic Chemistry Faculty of Chemistry, USTHB, BP 32, El Alia, 16111, Algiers (Algeria); Trari, Mohamed [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry, USTHB, BP 32, El Alia, 16111, Algiers (Algeria); Bouguelia, Aissa, E-mail: labosver@gmail.com [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry, USTHB, BP 32, El Alia, 16111, Algiers (Algeria)

    2009-09-30

    The transport phenomena across ion exchange membrane may be enhanced by applying various strengths inside or outside the system. The electrical current, generated by n-type semiconductor, is used to catalyse the separation of metal ions. The cation exchange membrane located between the two compartments allows both the separation and concentration of M{sup n+} (Ag{sup +}, Cu{sup 2+}, Pb{sup 2+} and Ni{sup 2+}). The flows of M{sup n+} from the aqueous solution to-and inside the membrane are monitored by the determination of the fluxes and the potentials. In this study, the four cations are investigated alone or in quaternary systems. From photoelectrochemical measurement, the gap of Bi{sub 2}S{sub 3} is found to be indirect at 1.65 eV. The shape of photocurrent potential curve and the negative flat band potential (-1.02 V{sub SCE}) give evidence of n-type character. The conduction band (-1.25 V{sub SCE}) yields thermodynamically M{sup 2+} photoreduction and catalyzes the diffusion process. The photoelectrode Bi{sub 2}S{sub 3} makes the flux twofold greater than that observed in the dark. In all cases, the potential of the electrode M{sup 2+}/M in the feed compartment increases until a maximal value, reached at {approx}100 min above which it undergoes a diminution. The membrane is more selective to Cu{sup 2+} and this selectivity decreases in the quaternary system.

  1. Lateral diffusion, function, and expression of the slow channel congenital myasthenia syndrome αC418W nicotinic receptor mutation with changes in lipid raft components.

    Science.gov (United States)

    Oyola-Cintrón, Jessica; Caballero-Rivera, Daniel; Ballester, Leomar; Baéz-Pagán, Carlos A; Martínez, Hernán L; Vélez-Arroyo, Karla P; Quesada, Orestes; Lasalde-Dominicci, José A

    2015-10-30

    Lipid rafts, specialized membrane microdomains in the plasma membrane rich in cholesterol and sphingolipids, are hot spots for a number of important cellular processes. The novel nicotinic acetylcholine receptor (nAChR) mutation αC418W, the first lipid-exposed mutation identified in a patient that causes slow channel congenital myasthenia syndrome was shown to be cholesterol-sensitive and to accumulate in microdomains rich in the membrane raft marker protein caveolin-1. The objective of this study is to gain insight into the mechanism by which lateral segregation into specialized raft membrane microdomains regulates the activable pool of nAChRs. We performed fluorescent recovery after photobleaching (FRAP), quantitative RT-PCR, and whole cell patch clamp recordings of GFP-encoding Mus musculus nAChRs transfected into HEK 293 cells to assess the role of cholesterol and caveolin-1 (CAV-1) in the diffusion, expression, and functionality of the nAChR (WT and αC418W). Our findings support the hypothesis that a cholesterol-sensitive nAChR might reside in specialized membrane microdomains that upon cholesterol depletion become disrupted and release the cholesterol-sensitive nAChRs to the pool of activable receptors. In addition, our results in HEK 293 cells show an interdependence between CAV-1 and αC418W that could confer end plates rich in αC418W nAChRs to a susceptibility to changes in cholesterol levels that could cause adverse drug reactions to cholesterol-lowering drugs such as statins. The current work suggests that the interplay between cholesterol and CAV-1 provides the molecular basis for modulating the function and dynamics of the cholesterol-sensitive αC418W nAChR.

  2. Fabrication of conducting-filament-embedded indium tin oxide electrodes: application to lateral-type gallium nitride light-emitting diodes.

    Science.gov (United States)

    Kim, Hee-Dong; Kim, Kyeong Heon; Kim, Su Jin; Kim, Tae Geun

    2015-11-02

    A novel conducting filament (CF)-embedded indium tin oxide (ITO) film is fabricated using an electrical breakdown method. To assess the performance of this layer as an ohmic contact, it is applied to GaN (gallium nitride) light-emitting diodes (LEDs) as a p-type electrode for comparison with typical GaN LEDs using metallic ITO. The operating voltage and output power of the LED with the CF embedded ITO are 3.93 V and 8.49 mW, respectively, at an injection current of 100 mA. This is comparable to the operating voltage and output power of the conventionally fabricated LEDs using metallic ITO (3.93 V and 8.43 mW). Moreover, the CF-ITO LED displays uniform and bright light emission indicating excellent current injection and spreading. These results suggest that the proposed method of forming ohmic contacts is at least as effective as the conventional method.

  3. Discharge Process of Insertion Electrodes Controlled by Lithium Ion Diffusion in Solid Materials%锂离子固相扩散控制下的材料放电过程

    Institute of Scientific and Technical Information of China (English)

    唐致远; 薛建军; 李建刚; 王占良

    2001-01-01

    从理论上分析了在锂离子固相扩散控制条件下 ,电极材料的恒流放电过程 .数值计算的结果表明 ,Q值(放电时率和扩散时间常数之比)对材料的放电容量有非常重要的影响 .模拟了 LiMn2O4正极材料和石墨负极材料的恒流放电曲线 ,分析了颗粒粒径对这两种材料放电容量的影响 .%We have analyzed the galvanostatic discharge process of insertion electrodes controlled by lithium ion diffusion in solid materials. It is demonstrated by mathematic calculation that the discharge capacity of insertion electrode depends on the value of Q(defined as the ratio of discharge hour rate and diffusion time constant). The galvanostatic discharge curve of spinel LiMn2O4 cathode and graphite anode have been simulated. The effect of particle size on the discharge capacity of spinel LiMn2O4 cathode and graphite anode is evaluated.

  4. Impact of Polytetrafluoroethylene Emulsion Binder Pretreatment with Ethanol on the Performance of Gas Diffusion Electrodes%粘结剂聚四氟乙烯乳液经过乙醇预处理后对气体扩散电极性能的影响

    Institute of Scientific and Technical Information of China (English)

    李芬; 徐献芝; 宋辉; 熊晋; 吴飞

    2009-01-01

    Polytetrafluoroethylene (PTFE) emulsion used as a binder for gas diffusion electrodes was pretreated with ethanol before use in electrodes. The surface topography of the gas diffusion electrodes was characterized by scanning electron microscopy (SEM). The BET and Langmuir special surface areas and pore distribution of the gas diffusion electrode were measured using a surface area detector. A zinc-air battery was then assembled and included this pretreated gas diffusion electrode. Under different current densities, the potential changes of the gas diffusion electrodes vs a zinc anode was measured. The impact of the PTFE emulsion alcoholic pretreatment on the performance of the gas diffusion electrodes was studied. The experimental results show that the porous structure of the catalytic activity layers and the gas diffusion layers increase with pretreatment. The reaction zones also increase with an increase in the catalytic activity of the layer's porous structure. Transport of the reactant gas is easier as the porous structure of the gas diffusion layers increase. The polarization potential of the gas diffusion electrode working under a large current density thus decreased.%在气体扩散电极的制作工艺中,加入乙醇对粘结剂聚四氟乙烯(PTFE)进行预处理.通过伞自动微孔物理化学吸附仪对气体扩散电极进行BET比表面积、Langmuir比表面积、孔分布等进行测试,并用扫描电子显微镜(SEM)检测观察电极表观形貌.以锌电极作为负极组装成锌空气电池,检测在不同的电流密度下气体扩散电极相对锌电极的电位变化,研究PTFE乳液经过乙醇预处理后对电极性能的影响.结果显示,PTFE乳液经过乙醇处理后,先膨胀后收缩,能够增加催化层和气体扩散层的孔隙结构和比表面积,从而使得电极有效电化学反应场所相应增多,减低电极在大电流密度条件下放电时的极化过电位.

  5. Magnetohydrodynamic electrode

    Science.gov (United States)

    Boquist, Carl W.; Marchant, David D.

    1978-01-01

    A ceramic-metal composite suitable for use in a high-temperature environment consists of a refractory ceramic matrix containing 10 to 50 volume percent of a continuous high-temperature metal reinforcement. In a specific application of the composite, as an electrode in a magnetohydrodynamic generator, the one surface of the electrode which contacts the MHD fluid may have a layer of varying thickness of nonreinforced refractory ceramic for electrode temperature control. The side walls of the electrode may be coated with a refractory ceramic insulator. Also described is an electrode-insulator system for a MHD channel.

  6. The N-formyl methionyl peptide, formyl-methionyl-leucyl phenylalanine (fMLF) increases the lateral diffusion of complement receptor 1 (CR1/CD35) in human neutrophils; a causative role for oxidative metabolites?

    Science.gov (United States)

    Rasmusson, B J; Carpentier, J L; Paccaud, J P; Magnusson, K E

    1996-10-01

    The effects of the N-formyl methionyl peptide, formyl-methionyl-leucyl phenylalanine (fMLF) on the lateral mobility of the complement receptor type 1 (CR1/CD35) in glass-adherent human neutrophils were investigated, using fluorescence recovery after photobleaching (FRAP) and confocal microscopy (CSLM). It was found that addition of 0.1-1 microM fMLF increased the diffusion constant (D) of CR1/CD35 to 167-228% of controls. No effect was observed on the receptor distribution or the mobile fraction of receptors. The effect of fMLF on the lateral diffusion of CR1/CD35 could be totally inhibited by addition of pertussis toxon (PD, 250 ng/ml) or of the free radical scavenger enzymes superoxide dismutase (SOD, 2000 U/ml) and catalase (CAT, 200 U/ml), added together the results show that oxidative metabolites produced by neutrophils in response to fMLF can modulate CR1/CD35 diffusion, and indicate a regulatory role for oxygen radicals in phagocytosis.

  7. Nanoparticle-electrode collision processes: Investigating the contact time required for the diffusion-controlled monolayer underpotential deposition on impacting nanoparticles

    Science.gov (United States)

    Cutress, Ian J.; Rees, Neil V.; Zhou, Yi-Ge; Compton, Richard G.

    2011-09-01

    Recent work on faradaic processes occurring during thermal nanoparticle-electrode collisions contrasts significantly from analogous research using ultrasonically-driven microparticles, where no faradaic signals were found. It is suggested that this might be explained by the differences in both particle size and contact time. To investigate this, we present results from adapted Monte Carlo random walk simulations. Using the underpotential deposition of thallium onto silver nanoparticles as a model system, it is found that an estimated minimum contact time of ca. 10-4 s is required to deposit a complete monolayer (from a 10 mM solution) onto a nanoparticle of radius 45 nm.

  8. Treatment of Reactive Red waste water by a gas diffusion electrolysis method using copper foam electrode%泡沫铜气体扩散电极处理活性艳红废水

    Institute of Scientific and Technical Information of China (English)

    应迪文; 潘思文; 贾金平; 王浩伟

    2014-01-01

    Copper foam material was introduced and used as the gas diffusion cathode in this study. This electrode has low electrical resistivity, good physical strength, and high porosity. Based on these features, a gas diffusion electrolysis waste water treatment method was developed. According to the experimental data, copper foam electrode was extremely good for H2 O2 generation on the cathode in gas diffusion electrode reactor, and 14. 29 mg·L-1 of H2 O2 was detected in 120 min at 1. 65 V which is extremely low comparing with previous research. The gas diffusion electrode reactor using copper foam cathode degraded Reactive Red X-3B rapidly. Decoloration of 96�19% was achieved in 120 min only under 2 V. The structures of naphthalene nucleus, triazine ring and benzene ring, were broken up simultaneously during the degradation according to the result of UV-vis absorption spectra and LC-TOF MS. The energy consumption of the new reactor was much lower than traditional electrochemical reactor due to its low electrolysis voltage of 2 V, much lower than previous voltages of 8-25 V. At this voltage, the uneffetive electrolysis of H2 O was widely inhibited. However, the degradation efficiency was still high because of the high reactive intermediates of ·OH. This method is promising for low-cost and high efficient waste water treatment.%采用铜基泡沫材料作为阴极,并根据泡沫材料电阻小、强度高、孔隙多的特点设计气体扩散电极,开发了一套基于铜基泡沫材料的气体扩散电解废水处理方法.实验结果表明,该方法在电解电压仅为1.65 V时,120 min内原位生成14.29 mg·L-1的H2 O2.采用该系统对活性艳红废水进行降解,结果表明其在电解电压为2 V时即可快速高效地降解活性艳红X-3B模拟染料废水,120 min内模拟废水色度去除率达96.19%,色度被快速消除.UV-Vis与LC-TOF MS检测结果表明,降解过程中,萘环、三嗪结构及较稳定的苯

  9. Communication: Development of standing evanescent-wave fluorescence correlation spectroscopy and its application to the lateral diffusion of lipids in a supported lipid bilayer

    Science.gov (United States)

    Otosu, Takuhiro; Yamaguchi, Shoichi

    2017-07-01

    We present standing evanescent-wave fluorescence correlation spectroscopy (SEW-FCS). This technique utilizes the interference of two evanescent waves which generates a standing evanescent-wave. Fringe-pattern illumination created by a standing evanescent-wave enables us to measure the diffusion coefficients of molecules with a super-resolution corresponding to one fringe width. Because the fringe width can be reliably estimated by a simple procedure, utilization of fringes is beneficial to quantitatively analyze the slow diffusion of molecules in a supported lipid bilayer (SLB), a model biomembrane formed on a solid substrate, with the timescale relevant for reliable FCS analysis. Furthermore, comparison of the data between SEW-FCS and conventional total-internal reflection FCS, which can also be performed by the SEW-FCS instrument, effectively eliminates the artifact due to afterpulsing of the photodiode detector. The versatility of SEW-FCS is demonstrated by its application to various SLBs.

  10. Tobacco mosaic virus (TMV) replicase and movement protein function synergistically in facilitating TMV spread by lateral diffusion in the plasmodesmal desmotubule of Nicotiana benthamiana.

    Science.gov (United States)

    Guenoune-Gelbart, Dana; Elbaum, Michael; Sagi, Guy; Levy, Amit; Epel, Bernard L

    2008-03-01

    Virus spread through plasmodesmata (Pd) is mediated by virus-encoded movement proteins (MPs) that modify Pd structure and function. The MP of Tobacco mosaic virus ((TMV)MP) is an endoplasmic reticulum (ER) integral membrane protein that binds viral RNA (vRNA), forming a vRNA:MP:ER complex. It has been hypothesized that (TMV)MP causes Pd to dilate, thus potentiating a cytoskeletal mediated sliding of the vRNA:MP:ER complex through Pd; in the absence of MP, by contrast, the ER cannot move through Pd. An alternate model proposes that cell-to-cell spread takes place by diffusion of the MP:vRNA complex in the ER membranes which traverse Pd. To test these models, we measured the effect of (TMV)MP and replicase expression on cell-to-cell spread of several green fluorescent protein-fused probes: a soluble cytoplasmic protein, two ER lumen proteins, and two ER membrane-bound proteins. Our data support the diffusion model in which a complex that includes ER-embedded MP, vRNA, and other components diffuses in the ER membrane within the Pd driven by the concentration gradient between an infected cell and adjacent noninfected cells. The data also suggest that the virus replicase and MP function together in altering Pd conductivity.

  11. A Study of Gas Diffusion Electrodes for the Coupled Reaction of Water Electrolysis and Electrocatalytic Benzene Hydrogenation%电催化苯加氢与水电解耦合反应的气体扩散电极研究

    Institute of Scientific and Technical Information of China (English)

    黄海燕; 俞英; 王晶

    2005-01-01

    Gas diffusion electrodes are applied to the coupled reaction of water electrolysis and electrocatalytic benzene hydrogenation. The effects of the preparation conditions of electrodes, electrolyte acidity, the concentration of benzene and water vapor, and the flow rate of N2 are investigated by evaluating the efficiency of the current. Furthermore, the optimal operational conditions have been ascertained. The results of our experiment show that gas diffusion electrodes have good performance when the content of PTFE is 10% (wt) and that of Nafion is 0.75mg/cm2. The optimal operational conditions are as follows: The temperature of electrolysis is 70℃, acidity 0.5mol/L, the concentration of benzene 26%,the concentration of vapor 10%, the flow rate of N2 80mL/min-240mL/min. The efficiency of the current can reach 35%under optimal operational conditions. Then, a conclusion can be drawn that gas diffusion electrodes can improve the rate of the coupled reaction effectively.

  12. Lateral IBIC characterization of single crystal synthetic diamond detectors

    CERN Document Server

    Giudice, A Lo; Manfredotti, C; Marinelli, M; Milani, E; Picollo, F; Prestopino, G; Re, A; Rigato, V; Verona, C; Verona-Rinati, G; Vittone, E

    2016-01-01

    In order to evaluate the charge collection efficiency (CCE) profile of single-crystal diamond devices based on a p type/intrinsic/metal configuration, a lateral Ion Beam Induced Charge (IBIC) analysis was performed over their cleaved cross sections using a 2 MeV proton microbeam. CCE profiles in the depth direction were extracted from the cross-sectional maps at variable bias voltage. IBIC spectra relevant to the depletion region extending beneath the frontal Schottky electrode show a 100% CCE, with a spectral resolution of about 1.5%. The dependence of the width of the high efficiency region from applied bias voltage allows the constant residual doping concentration of the active region to be evaluated. The region where the electric field is absent shows an exponentially decreasing CCE profile, from which it is possible to estimate the diffusion length of the minority carriers by means of a drift-diffusion model.

  13. Morphology Effect of Vertical Graphene on the High Performance of Supercapacitor Electrode.

    Science.gov (United States)

    Zhang, Yu; Zou, Qionghui; Hsu, Hua Shao; Raina, Supil; Xu, Yuxi; Kang, Joyce B; Chen, Jun; Deng, Shaozhi; Xu, Ningsheng; Kang, Weng P

    2016-03-23

    Graphene and its composites are widely investigated as supercapacitor electrodes due to their large specific surface area. However, the severe aggregation and disordered alignment of graphene sheets hamper the maximum utilization of its surface area. Here we report an optimized structure for supercapacitor electrode, i.e., the vertical graphene sheets, which have a vertical structure and open architecture for ion transport pathway. The effect of morphology and orientation of vertical graphene on the performance of supercapacitor is examined using a combination of model calculation and experimental study. Both results consistently demonstrate that the vertical graphene electrode has a much superior performance than that of lateral graphene electrode. Typically, the areal capacitances of a vertical graphene electrode reach 8.4 mF/cm(2) at scan rate of 100 mV/s; this is about 38% higher than that of a lateral graphene electrode and about 6 times higher than that of graphite paper. To further improve its performance, a MnO2 nanoflake layer is coated on the surface of graphene to provide a high pseudocapacitive contribution to the overall areal capacitance which increases to 500 mF/cm(2) at scan rate of 5 mV/s. The reasons for these significant improvements are studied in detail and are attributed to the fast ion diffusion and enhanced charge storage capacity. The microscopic manipulation of graphene electrode configuration could greatly improve its specific capacitance, and furthermore, boost the energy density of supercapacitor. Our results demonstrate that the vertical graphene electrode is more efficient and practical for the high performance energy storage device with high power and energy densities.

  14. Graphene based nanocomposite hybrid electrodes for supercapacitors

    Science.gov (United States)

    Aphale, Ashish N.

    There is an unmet need to develop high performance energy storage systems (ESS), capable of storing energy from both renewable and non-renewable sources to meet the current energy crisis and depletion of non-renewable sources. Amongst many available ESS, supercapacitors (ECs) are the most promising because they exhibit a high charge/discharge rate and power density, along with a long cycle life. The possibility of exploring the use of atomically thin carbon allotropes like graphene, carbon nanotubes (CNTs) and electrically conducting polymers (ECPs) such as polypyrrole (PPy) has been studied as a high performance conducting electrodes in supercapacitor application. A novel templated sustainable nanocomposite electrode has been fabricated using cellulose extracted from Cladophora c. aegagropila algae as component of the assembled supercapacitor device which later has been transitioned to a unique template-less freestanding nanocomposite supercapacitor electrode. The specific capacitance of polypyrrole-graphene-cellulose nanocomposite as calculated from cyclic voltammetry curve is 91.5 F g -1 at the scan rate 50 m Vs-1 in the presence of 1M NaCl electrolyte. The open circuit voltage of the device with polypyrrole -graphene-cellulose electrode was found to be around 225 m V and that of the polypyrrole -cellulose device is only 53 m V without the presence of graphene in the nanocomposite electrode. Understanding the fundamentals by fabricating template nanocomposite electrode, it led to fabricate a unique nanocomposite template-less freestanding film which comprises of polypyrrole-graphene-CNT hybrid. Various experiments have been performed using different electrolytes such ascorbic acid, sodium sulfate and sulfuric acid in different scan rates. The specific capacitance of polypyrrole-graphene-CNT nanocomposite with 0.1 wt% of graphene-CNT, as calculated from cyclic voltammetry curve is 450 F g-1 at the scan rate 5 m V s-1. For the first time a nanofibrous membrane has

  15. High temperature behavior of multi-region direct current current-voltage spectroscopy and relationship with shallow-trench-isolation-based high-voltage laterally diffused metal-oxide-semiconductor field-effect-transistors reliability

    Science.gov (United States)

    He, Yandong; Zhang, Ganggang; Zhang, Xing

    2014-01-01

    With the process compatibility with the mainstream standard complementary metal-oxide-semiconductor (CMOS), shallow trench isolation (STI) based laterally diffused metal-oxide-semiconductor (LDMOS) devices have become popular for its better tradeoff between breakdown voltage and performance, especially for smart power applications. A multi-region direct current current-voltage (MR-DCIV) technique with spectroscopic features was demonstrated to map the interface state generation in the channel, accumulation and STI drift regions. High temperature behavior of MR-DCIV spectroscopy was analyzed and a physical model was verified. Degradation of STI-based LDMOS transistors under high temperature reverse bias (HTRB) stress is experimentally studied by MR-DCIV spectroscopy. The impact of interface state location on device electrical characteristics was investigated. Our results show that the major contribution to HTRB degradation, in term of the on-resistance degradation, was attributed to interface state generation under STI drift region.

  16. Nonequilibrium Thermodynamics of Porous Electrodes

    CERN Document Server

    Ferguson, Todd R

    2012-01-01

    We review classical porous electrode theory and extend it to non-ideal active materials, including those capable of phase transformations. Using principles of non-equilibrium thermodynamics, we relate the cell voltage, ionic fluxes, and Faradaic charge-transfer kinetics to the variational electrochemical potentials of ions and electrons. The Butler-Volmer exchange current is consistently expressed in terms of the activities of the reduced, oxidized and transition states, and the activation overpotential is defined relative to the local Nernst potential. We also apply mathematical bounds on effective diffusivity to estimate porosity and tortuosity corrections. The theory is illustrated for a Li-ion battery with active solid particles described by a Cahn-Hilliard phase-field model. Depending on the applied current and porous electrode properties, the dynamics can be limited by electrolyte transport, solid diffusion and phase separation, or intercalation kinetics. In phase-separating porous electrodes, the model...

  17. Thin film fuel cell electrodes.

    Science.gov (United States)

    Asher, W. J.; Batzold, J. S.

    1972-01-01

    Earlier work shows that fuel cell electrodes prepared by sputtering thin films of platinum on porous vycor substrates avoid diffusion limitations even at high current densities. The presented study shows that the specific activity of sputtered platinum is not unusually high. Performance limitations are found to be controlled by physical processes, even at low loadings. Catalyst activity is strongly influenced by platinum sputtering parameters, which seemingly change the surface area of the catalyst layer. The use of porous nickel as a substrate shows that pore size of the substrate is an important parameter. It is noted that electrode performance increases with increasing loading for catalyst layers up to two microns thick, thus showing the physical properties of the sputtered layer to be different from platinum foil. Electrode performance is also sensitive to changing differential pressure across the electrode. The application of sputtered catalyst layers to fuel cell matrices for the purpose of obtaining thin total cells appears feasible.

  18. Graphene-based battery electrodes having continuous flow paths

    Science.gov (United States)

    Zhang, Jiguang; Xiao, Jie; Liu, Jun; Xu, Wu; Li, Xiaolin; Wang, Deyu

    2014-05-24

    Some batteries can exhibit greatly improved performance by utilizing electrodes having randomly arranged graphene nanosheets forming a network of channels defining continuous flow paths through the electrode. The network of channels can provide a diffusion pathway for the liquid electrolyte and/or for reactant gases. Metal-air batteries can benefit from such electrodes. In particular Li-air batteries show extremely high capacities, wherein the network of channels allow oxygen to diffuse through the electrode and mesopores in the electrode can store discharge products.

  19. Estudo da degradação de ranitidina via H2O2 eletrogerado/Fenton em um reator eletroquímico com eletrodos de difusão gasosa Study of the ranitidine degradation by H2O2 electrogenerated/Fenton in a electrochemical reactor with gas diffusion electrode

    Directory of Open Access Journals (Sweden)

    André A. G. F. Beati

    2009-01-01

    Full Text Available The study of the electrochemical degradation of the ranitidine was developed using an electrochemical reactor with a gas diffusion electrode (GDE as cathode. The electrolysis experiments was performed at constant current (1 4 A. The process reached a production of 630 mg L-1 of the H2O2 at 7 A. The ranitidine concentrations was reduced in 99.9% (HPLC and chemical oxygen demand (COD was reduced in 86.7% by electro-Fenton.

  20. Microvoltammetric Electrodes.

    Science.gov (United States)

    1985-09-25

    Microvoltammetric Electrodes, J. 0. Howell, R. M. Wightman, Anal. Chem., 56, 524-529 (1984). 2. Flow Rate Independent Amperometric Cell , W. L. Caudill...Electroanal. Chem., 182, 113-122 (1985). C. List of all publications 1. Flow Rate Independent Amperometric Cell , W. L. Caudill, J. 0. Howell, R. M

  1. Lateral Concepts

    Directory of Open Access Journals (Sweden)

    Christopher Gad

    2016-06-01

    Full Text Available This essay discusses the complex relation between the knowledges and practices of the researcher and his/her informants in terms of lateral concepts. The starting point is that it is not the prerogative of the (STS scholar to conceptualize the world; all our “informants” do it too. This creates the possibility of enriching our own conceptual repertoires by letting them be inflected by the concepts of those we study. In a broad sense, the lateral means that there is a many-to-many relation between domains of knowledge and practice. However, each specific case of the lateral is necessarily immanent to a particular empirical setting and form of inquiry. In this sense lateral concepts are radically empirical since it locates concepts within the field. To clarify the meaning and stakes of lateral concepts, we first make a contrast between lateral anthropology and Latour’s notion of infra-reflexivity. We end with a brief illustration and discussion of how lateral conceptualization can re-orient STS modes of inquiry, and why this matters.

  2. Carbon nanotube macrofilm-based nanocomposite electrodes for energy applications

    Science.gov (United States)

    Cao, Zeyuan

    , Ni)) with CNT macofilms as high performance anodes for rechargeable lithium-ion batteries and as catalysts for oxygen reduction/evolution (ORR/OER). All MxOy-CNT macrofilm nanocomposites inherit the high specific capacity and cycling stability for lithium-ion batteries. NiO/SWNT and Co3O4/SWNT (200 °C) have their specialized high catalytic activities for ORR and OER in alkaline solutions, respectively. NiO/SWNT also exhibits an excellent electrochemical performance in asymmetric supercapacitors with a high power and energy density. Experimental measurements on electrochemical kinetics such as potentiostatic/galvanostatic intermittent titration techniques (PITT/GITT) are depended to understand the underlying improved Li+ diffusion behavior of nanocomposites. Critical effects of the film thickness have been identified. The CNT macrofilm with a thickness that is comparable to the characteristic diffusion length of 300~500 nm enables the nanocomposite with the highest Li+ chemical diffusion coefficient and thus an optimal electrochemical performance. The adhesive characteristic of CNT macrofilms is noticed for the first time after fragmentation by ultrasound that origins from irregular structures of laterally 2-D distributed CNT segments. The fragmented CNT macrofilms (FCNT) as "bifunctional" adhesive conductors promote a general approach to construct nanocomposite electrodes with both cathode and anode materials for lithium-ion batteries. An in-situ tribology method combining the wear track imaging and force measurement is employed to evaluate the adhesion strength of the adhesive FCNT conductors. The results show that the FCNT macrofilms have a higher adhesion strength than the conventional polymer binder polyvinylidene fluoride (PVDF). It is confirmed that the fabricated nanocomposite electrodes exhibit high rate and retention capabilities, superior to the electrodes using PVDF and carbon black. Thus, FCNT is recognized to be a competent substitute for polymer

  3. The relation of turbulence to diffusion in open-channel flows

    Science.gov (United States)

    Keefer, Thomas N.

    1971-01-01

    This investigation examines the interrelation between turbulent diffusion, dispersion, and the statistical properties of turbulence in an open-channel flow. The experiments were conducted in a 3. 87- foot wide flume over four boundary roughnesses. The results are from studies made of: (1) the influence of turbulence on the vertical and lateral diffusion of plumes of heated water and a neutrally-buoyant salt solution from a point source at the mid-depth of flow; (2) the velocity concentration covariance along the axis of a salt solution plume using a single-electrode conductivity probe and hot-film sensor; (3) lateral and longitudinal surface diffusion measured by dropping polyethylene particles on the water surface; and (4) longitudinal space-time velocity correlation measurements.

  4. Hot-carrier-induced linear drain current and threshold voltage degradation for thin layer silicon-on-insulator field P-channel lateral double-diffused metal-oxide-semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xin; Qiao, Ming; He, Yitao; Li, Zhaoji; Zhang, Bo, E-mail: bozhang@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, Sichuan 610054 (China)

    2015-11-16

    Hot-carrier-induced linear drain current (I{sub dlin}) and threshold voltage (V{sub th}) degradations for the thin layer SOI field p-channel lateral double-diffused MOS (pLDMOS) are investigated. Two competition degradation mechanisms are revealed and the hot-carrier conductance modulation model is proposed. In the channel, hot-hole injection induced positive oxide trapped charge and interface trap gives rise to the V{sub th} increasing and the channel conductance (G{sub ch}) decreasing, then reduces I{sub dlin}. In the p-drift region, hot-electron injection induced negative oxide trapped charge enhances the conductance of drift doping resistance (G{sub d}), and then increases I{sub dlin}. Consequently, the eventual I{sub dlin} degradation is controlled by the competition of the two mechanisms due to conductance modulation in the both regions. Based on the model, it is explained that the measured I{sub dlin} anomalously increases while the V{sub th} is increasing with power law. The thin layer field pLDMOS exhibits more severe V{sub th} instability compared with thick SOI layer structure; as a result, it should be seriously evaluated in actual application in switching circuit.

  5. A Pascalian lateral drift sensor

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, H., E-mail: hendrik.jansen@desy.de

    2016-09-21

    A novel concept of a layer-wise produced semiconductor sensor for precise particle tracking is proposed herein. In contrast to common semiconductor sensors, local regions with increased doping concentration deep in the bulk termed charge guides increase the lateral drift of free charges on their way to the read-out electrode. This lateral drift enables charge sharing independent of the incident position of the traversing particle. With a regular grid of charge guides the lateral charge distribution resembles a normalised Pascal's triangle for particles that are stopped in depths lower than the depth of the first layer of the charge guides. For minimum ionising particles a sum of binomial distributions describes the lateral charge distribution. This concept decouples the achievable sensor resolution from the pitch size as the characteristic length is replaced by the lateral distance of the charge guides.

  6. A Pascalian lateral drift sensor

    Science.gov (United States)

    Jansen, H.

    2016-09-01

    A novel concept of a layer-wise produced semiconductor sensor for precise particle tracking is proposed herein. In contrast to common semiconductor sensors, local regions with increased doping concentration deep in the bulk termed charge guides increase the lateral drift of free charges on their way to the read-out electrode. This lateral drift enables charge sharing independent of the incident position of the traversing particle. With a regular grid of charge guides the lateral charge distribution resembles a normalised Pascal's triangle for particles that are stopped in depths lower than the depth of the first layer of the charge guides. For minimum ionising particles a sum of binomial distributions describes the lateral charge distribution. This concept decouples the achievable sensor resolution from the pitch size as the characteristic length is replaced by the lateral distance of the charge guides.

  7. Diffusion formalism and applications

    CERN Document Server

    Dattagupta, Sushanta

    2013-01-01

    Within a unifying framework, Diffusion: Formalism and Applications covers both classical and quantum domains, along with numerous applications. The author explores the more than two centuries-old history of diffusion, expertly weaving together a variety of topics from physics, mathematics, chemistry, and biology. The book examines the two distinct paradigms of diffusion-physical and stochastic-introduced by Fourier and Laplace and later unified by Einstein in his groundbreaking work on Brownian motion. The author describes the role of diffusion in probability theory and stochastic calculus and

  8. Kinetics of electrochemical process of galena electrode in diethyldithiocarbamate solution

    Institute of Scientific and Technical Information of China (English)

    覃文庆; 邱冠周; 胡岳华; 徐竞

    2001-01-01

    The electrode process of galena in diethyldithiocarbamate (DDTC) solution at pH 11.4 has been investigated using cyclic voltammetry, potentiostatic and chronopotentiometry. Electrodeposit of PbD2 on galena electrode surface can occur while the electrode potential is higher than -0.05V. The relationship between the current density caused by diffusion and reaction time has been ascertained, and the diffusion coefficient of DDTC on galena surface in DDTC solution is about 1.12×10-6 cm2/s. A passive PbD2 film covers the surface of galena electrode.

  9. Lateral Mixing

    Science.gov (United States)

    2012-11-08

    being made on their analysis. A process we became very curious about was the separation of tendrils of warm salty water from the north wall figure 7...structure, and to remove the effect of internal waves by mapping this structure onto isopycnals. This has been very successful in elucidating lateral...we passed through the same water on multiple passes, and that changes in the horizontal structure of the water mas should be readily apparent from

  10. Iron serves as diffusion barrier in thermally regenerative galvanic cell

    Science.gov (United States)

    Crouthamel, C. E.

    1967-01-01

    Pure iron or iron-coated diaphragm provides a hydrogen diffusion electrode for a thermally regenerative galvanic cell. It allows the gas to diffuse through its interatomic spaces and resists the corrosive action of the cell environment.

  11. Lateral conduction infrared photodetector

    Science.gov (United States)

    Kim, Jin K.; Carroll, Malcolm S.

    2011-09-20

    A photodetector for detecting infrared light in a wavelength range of 3-25 .mu.m is disclosed. The photodetector has a mesa structure formed from semiconductor layers which include a type-II superlattice formed of alternating layers of InAs and In.sub.xGa.sub.1-xSb with 0.ltoreq.x.ltoreq.0.5. Impurity doped regions are formed on sidewalls of the mesa structure to provide for a lateral conduction of photo-generated carriers which can provide an increased carrier mobility and a reduced surface recombination. An optional bias electrode can be used in the photodetector to control and vary a cut-off wavelength or a depletion width therein. The photodetector can be formed as a single-color or multi-color device, and can also be used to form a focal plane array which is compatible with conventional read-out integrated circuits.

  12. AC impedance modelling study on porous electrodes of proton exchange membrane fuel cells using an agglomerate model

    Science.gov (United States)

    Gerteisen, Dietmar; Hakenjos, Alex; Schumacher, Jürgen O.

    A one-dimensional model of the PEM fuel cell cathode is developed to analyse ac impedance spectra and polarisation curves. The porous gas diffusion electrode is assumed to consist of a network of dispersed catalyst (Pt/C) forming spherically shaped agglomerated zones that are filled with electrolyte. The coupled differential equation system describes: ternary gas diffusion in the backing (O2 , N2 , water vapour), Fickian diffusion and Tafel kinetics for the oxygen reduction reaction (ORR) inside the agglomerates, proton migration with ohmic losses and double-layer charging in the electrode. Measurements are made of a temperature-controlled fuel cell with a geometric area of 1.4 cm × 1.4 cm. Lateral homogeneity is ensured by using a high stoichiometry of λmin . The model predicts the behaviour of measured polarisation curves and impedance spectra. It is found that a better humidification of the electrode leads to a higher volumetric double-layer capacity. The catalyst layer resistance shows the same behaviour depending on the humidification as the membrane resistance. Model parameters, e.g. Tafel slope, ionic resistance and agglomerate radius are varied. A sensitivity analysis of the model parameters is conducted.

  13. Solid oxide cell oxygen electrode with enhanced durability

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention provides various methods of producing a solid oxide cell with an enhanced durability. Dopants are provided at the interface of the electrode comprising LSM and electrolyte and prevent especially the diffusion of Mn from the electrode layer into the electrolyte, stabilizing...

  14. Analysis of the interfacial admittance in the case of a two-step two-electron electrode reaction with a diffusing intermediate, with application to the reduction of pyrazine

    NARCIS (Netherlands)

    Rueda, M.; Sluyters-Rehbach, M.; Sluyters, J.H.

    1987-01-01

    A critical evaluation is presented of the analysis of impedance or admittance data in the case of an electrode reaction proceeding by two consecutive one-electron transfers with a stable, solution-soluble intermediate. It is shown that the expression for this case, as derived by Armstrong and

  15. Regular arrays of microdisc electrodes: simulation quantifies the fraction of 'dead' electrodes.

    Science.gov (United States)

    Ordeig, Olga; Banks, Craig E; Davies, Trevor J; Del Campo, Javier; Mas, Roser; Muñoz, Francesc Xavier; Compton, Richard G

    2006-03-01

    Arrays of microdisc electrodes have found widespread use in electroanalysis. These are commonly produced lithographically and practical arrays may contain up to hundreds of individual disc electrodes (e.g. of gold, platinum, indium,...) to maximise sensitivity and minimise limits of detection. Typically, however, the lithographic fabrication process is imperfect resulting in a significant fraction (often tens of percent) of electrochemically inactive electrodes. We demonstrate that a 2-dimensional simulation based on the diffusion domain approximation in conjugation with simple experiments on the ferrocyanide redox couple in aqueous solutions can be used to rigorously 'count' the number of active electrodes in a non-destructive fashion. The agreement with an independent count in which active electrodes are identified via electro-plating with copper followed by ex situ microscopic examination is quantitatively excellent.

  16. The electrochemical impedance of metal hydride electrodes

    DEFF Research Database (Denmark)

    Valøen, Lars Ole; Lasia, Andrzej; Jensen, Jens Oluf

    2002-01-01

    The electrochemical impedance responses for different laboratory type metal hydride electrodes were successfully modeled and fitted to experimental data for AB5 type hydrogen storage alloys as well as one MgNi type electrode. The models fitted the experimental data remarkably well. Several AC......, explaining the experimental impedances in a wide frequency range for electrodes of hydride forming materials mixed with copper powder, were obtained. Both charge transfer and spherical diffusion of hydrogen in the particles are important sub processes that govern the total rate of the electrochemical...... hydrogen absorption/desorption reaction. To approximate the experimental data, equations describing the current distribution in porous electrodes were needed. Indications of one or more parallel reduction/oxidation processes competing with the electrochemical hydrogen absorption/desorption reaction were...

  17. Materials analyses and electrochemical impedance of implantable metal electrodes.

    Science.gov (United States)

    Howlader, Matiar M R; Ul Alam, Arif; Sharma, Rahul P; Deen, M Jamal

    2015-04-21

    Implantable electrodes with high flexibility, high mechanical fixation and low electrochemical impedance are desirable for neuromuscular activation because they provide safe, effective and stable stimulation. In this paper, we report on detailed materials and electrical analyses of three metal implantable electrodes - gold (Au), platinum (Pt) and titanium (Ti) - using X-ray photoelectron spectroscopy (XPS), scanning acoustic microscopy, drop shape analysis and electrochemical impedance spectroscopy. We investigated the cause of changes in electrochemical impedance of long-term immersed Au, Pt and Ti electrodes on liquid crystal polymers (LCPs) in phosphate buffered saline (PBS). We analyzed the surface wettability, surface and interface defects and the elemental depth profile of the electrode-adhesion layers on the LCP. The impedance of the electrodes decreased at lower frequencies, but increased at higher frequencies compared with that of the short-term immersion. The increase of impedances was influenced by the oxidation of the electrode/adhesion-layers that affected the double layer capacitance behavior of the electrode/PBS. The oxidation of the adhesion layer for all the electrodes was confirmed by XPS. Alkali ions (sodium) were adsorbed on the Au and Pt surfaces, but diffused into the Ti electrode and LCPs. The Pt electrode showed a higher sensitivity to surface and interface defects than that of Ti and Au electrodes. These findings may be useful when designing electrodes for long-term implantable devices.

  18. Lateral diffusion of peripheral membrane proteins on supported lipid bilayers is controlled by the additive frictional drags of (1) bound lipids and (2) protein domains penetrating into the bilayer hydrocarbon core.

    Science.gov (United States)

    Ziemba, Brian P; Falke, Joseph J

    2013-01-01

    Peripheral membrane proteins bound to lipids on bilayer surfaces play central roles in a wide array of cellular processes, including many signaling pathways. These proteins diffuse in the plane of the bilayer and often undergo complex reactions involving the binding of regulatory and substrate lipids and proteins they encounter during their 2D diffusion. Some peripheral proteins, for example pleckstrin homology (PH) domains, dock to the bilayer in a relatively shallow position with little penetration into the bilayer. Other peripheral proteins exhibit more complex bilayer contacts, for example classical protein kinase C isoforms (PKCs) bind as many as six lipids in stepwise fashion, resulting in the penetration of three PKC domains (C1A, C1B, C2) into the bilayer headgroup and hydrocarbon regions. A molecular understanding of the molecular features that control the diffusion speeds of proteins bound to supported bilayers would enable key molecular information to be extracted from experimental diffusion constants, revealing protein-lipid and protein-bilayer interactions difficult to study by other methods. The present study investigates a range of 11 different peripheral protein constructs comprised by 1-3 distinct domains (PH, C1A, C1B, C2, anti-lipid antibody). By combining these constructs with various combinations of target lipids, the study measures 2D diffusion constants on supported bilayers for 17 different protein-lipid complexes. The resulting experimental diffusion constants, together with the known membrane interaction parameters of each complex, are used to analyze the molecular features correlated with diffusional slowing and bilayer friction. The findings show that both (1) individual bound lipids and (2) individual protein domains that penetrate into the hydrocarbon core make additive contributions to the friction against the bilayer, thereby defining the 2D diffusion constant. An empirical formula is developed that accurately estimates the diffusion

  19. Lithographically fabricated nanopore-based electrodes for electrochemistry

    NARCIS (Netherlands)

    Lemay, Serge G.; Broek, van den Dennis M.; Storm, Arnold J.; Krapf, Diego; Smeets, Ralph M.M.; Heering, Hendrik A.; Dekker, Cees

    2005-01-01

    We report a new technique for fabricating electrodes for electrochemical applications with lateral dimensions in the range 15−200 nm and a reproducible, well-defined geometry. This technique allows determining the electrode size by electron microscopy prior to electrochemical measurements and withou

  20. FUEL CELL ELECTRODE MATERIALS

    Science.gov (United States)

    FUEL CELL ELECTRODE MATERIALS. RAW MATERIAL SELECTION INFLUENCES POLARIZATION BUT IS NOT A SINGLE CONTROLLING FACTOR. AVAILABLE...DATA INDICATES THAT AN INTERRELATIONSHIP OF POROSITY, AVERAGE PORE VOLUME, AND PERMEABILITY CONTRIBUTES TO ELECTRODE FUEL CELL BEHAVIOR.

  1. Microresonator electrode design

    Science.gov (United States)

    Olsson, III, Roy H.; Wojciechowski, Kenneth; Branch, Darren W.

    2016-05-10

    A microresonator with an input electrode and an output electrode patterned thereon is described. The input electrode includes a series of stubs that are configured to isolate acoustic waves, such that the waves are not reflected into the microresonator. Such design results in reduction of spurious modes corresponding to the microresonator.

  2. A Simple Hydrogen Electrode

    Science.gov (United States)

    Eggen, Per-Odd

    2009-01-01

    This article describes the construction of an inexpensive, robust, and simple hydrogen electrode, as well as the use of this electrode to measure "standard" potentials. In the experiment described here the students can measure the reduction potentials of metal-metal ion pairs directly, without using a secondary reference electrode. Measurements…

  3. The Composite Insertion Electrode

    DEFF Research Database (Denmark)

    Atlung, Sven; Zachau-Christiansen, Birgit; West, Keld

    1984-01-01

    The specific energy obtainable by discharge of porous insertion electrodes is limited by electrolyte depletion in thepores. This can be overcome using a solid ion conductor as electrolyte. The term "composite" is used to distinguishthese electrodes from porous electrodes with liquid electrolyte...

  4. A Simple Hydrogen Electrode

    Science.gov (United States)

    Eggen, Per-Odd

    2009-01-01

    This article describes the construction of an inexpensive, robust, and simple hydrogen electrode, as well as the use of this electrode to measure "standard" potentials. In the experiment described here the students can measure the reduction potentials of metal-metal ion pairs directly, without using a secondary reference electrode. Measurements…

  5. Insulated ECG electrodes

    Science.gov (United States)

    Portnoy, W. M.; David, R. M.

    1973-01-01

    Insulated, capacitively coupled electrode does not require electrolyte paste for attachment. Other features of electrode include wide range of nontoxic material that may be employed for dielectric because of sputtering technique used. Also, electrode size is reduced because there is no need for external compensating networks with FET operational amplifier.

  6. A Method for Generating Diffuse Discharge via Repetitive Nanosecond Pulses and Wire Electrodes in Room-temperature Atmospheric Air%利用重复频率纳秒脉冲和线电极产生常温常压下的大气压弥散放电

    Institute of Scientific and Technical Information of China (English)

    李黎; 刘云龙; 俞斌; 葛亚峰; 林福昌

    2014-01-01

    The non-equilibrium plasmas produced by diffuse discharges have a great potential of application in many high technology fields. In room-temperature atmospheric air, the formation mechanism of non-equilibrium plasma is discussed and analysed. It is concluded that generating diffuse discharge in open air should meet the three conditions: low-voltage excitation, plentiful electron avalanches and temperature inhibition of spatial charge particles. A method of generating diffuse discharge is proposed and implemented. Based on runaway electrons breakdown theory, a low duty-ratio, high voltage repetitive nanosecond pulse generator is chosen as discharge excitation source. Using the wire-electrodes with small curvature radius, the gaps with highly non-uniform electrical field are structured. The experiments are performed in linear-type and ring-type electrode pairs. The results prove that the proposed method can generate typical diffuse discharges in cm. gaps via nanosecond pluses with less than 100kV peak voltage, hundreds of Hz repetitive frequency.%大气压弥散放电产生非热平衡等离子体在诸多高新技术领域具有较大应用潜力。分析了在常温常压的大气压条件下,形成和维持非热平衡等离子体的机制,提出了实现弥散放电应设法满足低放电电压、多电子崩发展和带电粒子温度抑制的条件。由此设计了在开放的大气压空气环境中实现大面积弥散放电的装置。根据逃逸电子击穿理论,选择重复频率、较低占空比的纳秒脉冲电激励方式作为弥散放电的低电压驱动源。利用线型电极的小曲率半径,构成极不均匀电场间隙。弥散放电分别在直线型电极和圆环型电极中进行。实验结果表明,所研制的放电装置能够以百kV以内峰值纳秒脉冲电压、数百Hz的频率激励若干厘米等级间距的大气压弥散放电。

  7. Template-directed porous electrodes in electroanalysis.

    Science.gov (United States)

    Walcarius, Alain

    2010-01-01

    Nano- and/or macrostructuring of electrode surfaces has recently emerged as a powerful method of improving the performances of electrochemical devices by enhancing both molecular accessibility and rapid mass transport via diffusion, by increasing the electroactive surface area in comparison to the geometric one, and/or by providing confinement platforms for hosting suitable reagents. This brief overview highlights how template technology offers advantages in terms of designing new types of porous electrodes-mostly based on thin films, and functionalized or not-and discusses their use in analytical chemistry via some recent examples from the literature on electrochemical sensors and biosensors.

  8. Inkjet Impregnation for Tailoring Air Electrode Microstructure to Improve Solid Oxide Cells Performance

    KAUST Repository

    Da’as, Eman H.

    2015-09-30

    The urge to lower the operating temperature of solid oxide cells (SOCs) to the intermediate ranges between 500-700°C motivated the research into impregnation processes, which offer highly efficient SOC air electrodes at low operating temperatures. Lack of controllability and reproducibility of this technique in the conventional way is still considered as an inadequacy for industrialization since it is performed manually. Therefore, inkjet-printing technology was proposed as an adequate approach to perform scalable and controllable impregnation for SOC air electrodes, which in turn leads to low operating temperatures. Composite LSM-ionic conductive air electrodes of weight ratio 1:2 were fabricated by inkjet impregnation of lanthanum strontium manganite (La0.8Sr0.2MnO3) precursor nitrates onto a porous ionic conductive backbone structure. First, porous yttria stabilized zirconia (8YSZ) substrates prepared by tape casting were used to study the influence of the printing parameters on the lateral dispersion and penetration of LSM ink inside the pores. XRD analysis confirmed the formation of LSM phase after calcination at 800°C for 2 h, while SEM revealed the formation of LSM nanostructures. It has been found by optical microscope observations that the spacing between the drops and the substrate temperature have a significant role in controlling the printing process. Next, the optimized printing parameters were applied in the inkjet impregnation of the LSM ink into porous YSZ electrodes that were spin coated on both sides of dense YSZ layers. LSM-YSZ composite air electrodes achieved an area specific resistance (ASR) of around 0.29 Ω.cm2 at 700°C. The performance of LSM-YSZ composite electrodes was influenced by the microstructure and the thickness, and by the electrode/electrolyte interface characteristics. As a result, the enhancement in LSM-YSZ composite electrode performance was observed due to the better percolation in LSM, YSZ and oxygen diffusion. Finally

  9. Diffusion MRI

    Science.gov (United States)

    Fukuyama, Hidenao

    Recent advances of magnetic resonance imaging have been described, especially stressed on the diffusion sequences. We have recently applied the diffusion sequence to functional brain imaging, and found the appropriate results. In addition to the neurosciences fields, diffusion weighted images have improved the accuracies of clinical diagnosis depending upon magnetic resonance images in stroke as well as inflammations.

  10. Electrode Configurations in Atmospheric Pressure Plasma Jets

    Science.gov (United States)

    Lietz, Amanda M.; Kushner, Mark J.

    2016-09-01

    Atmospheric pressure plasma jets (APPJs) are being studied for emerging medical applications including cancer treatment and wound healing. APPJs typically consist of a dielectric tube through which a rare gas flows, sometimes with an O2 or H2O impurity. In this paper, we present results from a computational study of APPJs using nonPDPSIM, a 2-D plasma hydrodynamics model, with the goal of providing insights on how the placement of electrodes can influence the production of reactive species. Gas consisting of He/O2 = 99.5/0.5 is flowed through a capillary tube at 2 slpm into humid air, and a pulsed DC voltage is applied. An APPJ with two external ring electrodes will be compared with one having a powered electrode inside and a ground electrode on the outside. The consequences on ionization wave propagation and the production of reactive oxygen and nitrogen species (RONS) will be discussed. Changing the electrode configuration can concentrate the power deposition in volumes having different gas composition, resulting in different RONS production. An internal electrode can result in increased production of NOx and HNOx by increasing propagation of the ionization wave through the He dominated plume to outside of the tube where humid air is diffusing into the plume. Work supported by US DOE Office of Fusion Energy Science and the National Science Foundation.

  11. Quasi-solid state polymer electrolytes for dye-sensitized solar cells. Effect of the electrolyte components variation on the triiodide ion diffusion properties and charge-transfer resistance at platinum electrode

    Energy Technology Data Exchange (ETDEWEB)

    Nazmutdinova, G.; Sensfuss, S.; Schroedner, M. [Thuringian Institute for Textile and Plastics Research, Breitscheidstrasse 97, 07407 Rudolstadt (Germany); Hinsch, A. [Fraunhofer Institute for Solar Energy Systems, Heidenhofstrasse 2, 79110 Freiburg (Germany); Sastrawan, R. [Freiburg Materials Research Center FMF, Stefan-Meier-Street 21, 79104 Freiburg (Germany); Gerhard, D.; Himmler, S.; Wasserscheid, P. [Friedrich-Alexander-University, Egerlandstrasse 3, 91058 Erlangen (Germany)

    2006-11-30

    Quasi-solid state polymer electrolytes have been prepared from poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) as gelator for 1-ethyl-3-methylimidazolium based ionic liquids (with anions like trifluoromethanesulfonate [EMIM][TfO], bis(trifluoromethanesulfonyl)imide [EMIM][Tf{sub 2}N]) and polyacrylonitrile (PAN) for gelation of 1-ethyl-3-methylimidazolium dicyanamide [EMIM][DCA] as well as I{sup -}/I{sub 3}{sup -} as the redox couple. All electrolytes exhibit high ionic conductivity in the range of 10{sup -3} S/cm. The effect of gelation, redox couple concentration, I{sup -}/I{sub 3}{sup -} ratio, choice of cations and additives on the triiodide diffusion and charge-transfer resistance of the platinum/electrolyte interface (R{sub ct}) were studied. The apparent diffusion coefficient of triiodide ion (D(I{sub 3}{sup -})) at various iodide/triiodide ratios in liquid and gelified electrolytes has been calculated from measurements of the diffusion limited current (I{sub lim}) in electrochemical cell resembling the set-up of a dye-sensitized solar cell. The charge-transfer resistance of the platinum/electrolyte interface as well as the capacitance of the electrical double layer (C{sub dl}) have been calculated from impedance measurements. Electrolytes with reduced content of polymer (2.5 wt.%) were doped with Al{sub 2}O{sub 3} particles of different sizes (50 nm, 300 nm, 1 {mu}m). The dispersion of the particles proceeds by speedy stirring of the hot electrolyte and the addition of PAN provides a homogeneous suspension. The addition of Al{sub 2}O{sub 3} particles causes a slight increase of the triiodide diffusion constants. Furthermore the suggested enhancement of the charge transfer rate shows a dependence on the size of the particles. (author)

  12. Interdigitated ring electrodes: Theory and experiment

    CERN Document Server

    Barnes, Edward O; Pozo-Ayuso, Diego F; Castaño-Alvarez, Mario; Lewis, Grace E M; Dale, Sara E C; Marken, Frank; Compton, Richard G

    2013-01-01

    The oxidation of potassium ferrocyanide, K_4Fe(CN)_6, in aqueous solution under fully supported conditions is carried out at interdigitated band and ring electrode arrays, and compared to theoretical models developed to simulate the processes. Simulated data is found to fit well with experimental results using literature values of diffusion coefficients for Fe(CN)_6^(4-) and Fe(CN)_6^(3-). The theoretical models are used to compare responses from interdigitated band and ring arrays, and the size of ring array required to approximate the response to a linear band array is investigated. An equation is developed for the radius of ring required for a pair of electrodes in a ring array to give a result with 5% of a pair of electrodes in a band array. This equation is found to be independent of the scan rate used over six orders of magnitude.

  13. Electrochemical hydrogenation of thiophene on SPE electrodes

    Science.gov (United States)

    Huang, Haiyan; Yuan, Penghui; Yu, Ying; Chung, Keng H.

    2017-01-01

    Electrochemical reduction desulfurization is a promising technology for petroleum refining which is environmental friendly, low cost and able to achieve a high degree of automation. Electrochemical hydrogenation of thiophene was performed in a three-electrode system which SPE electrode was the working electrode. The electrochemical desulfurization was studied by cyclic voltammetry and bulk electrolysis with coulometry (BEC) techniques. The results of cyclic voltammetry showed that the electrochemical hydrogenation reduction reaction occurred at -0.4V. The BEC results showed that the currents generated from thiophene hydrogenation reactions increased with temperature. According to Arrhenius equation, activation energy of thiophene electrolysis was calculated and lower activation energy value indicated it was diffusion controlled reaction. From the products of electrolytic reactions, the mechanisms of electrochemical hydrogenation of thiophene were proposed, consisting of two pathways: openingring followed by hydrogenation, and hydrogenation followed by ring opening.

  14. ELECTRIC ARC WELDING DEPOSITION OF METALLIC SURFACES BY VIBRATING ELECTRODE IN PROTECTIVE GAS MEDIUM

    OpenAIRE

    N. Spiridonov; A. Кudina; V. Кurash

    2013-01-01

    The paper presents methods for obtaining qualitative metallic surfaces by electric arc welding deposition while using consumable electrode in a protective gas medium and executing regularized drop transfer of electrode metal. The drop transfer efficiency of electrode metal and productivity of welding deposition are significantly increased due to excitation of lateral vibrations in the consumable electrode with preset amplitude. The paper describes a method and a device for welding deposition ...

  15. Pocket ECG electrode

    Science.gov (United States)

    Lund, Gordon F. (Inventor)

    1982-01-01

    A low-noise electrode suited for sensing electrocardiograms when chronically and subcutaneously implanted in a free-ranging subject. The electrode comprises a pocket-shaped electrically conductive member with a single entrance adapted to receive body fluids. The exterior of the member and the entrance region is coated with electrical insulation so that the only electrolyte/electrode interface is within the member remote from artifact-generating tissue. Cloth straps are bonded to the member to permit the electrode to be sutured to tissue and to provide electrical lead flexure relief.

  16. Handbook of reference electrodes

    CERN Document Server

    Inzelt, György; Scholz, Fritz

    2013-01-01

    Reference Electrodes are a crucial part of any electrochemical system, yet an up-to-date and comprehensive handbook is long overdue. Here, an experienced team of electrochemists provides an in-depth source of information and data for the proper choice and construction of reference electrodes. This includes all kinds of applications such as aqueous and non-aqueous solutions, ionic liquids, glass melts, solid electrolyte systems, and membrane electrodes. Advanced technologies such as miniaturized, conducting-polymer-based, screen-printed or disposable reference electrodes are also covered. Essen

  17. Durable fuel electrode

    DEFF Research Database (Denmark)

    2017-01-01

    the composite. The invention also relates to the use of the composite as a fuel electrode, solid oxide fuel cell, and/or solid oxide electrolyser. The invention discloses a composite for an electrode, comprising a three-dimensional network of dispersed metal particles, stabilised zirconia particles and pores...

  18. Membrane Bioprobe Electrodes

    Science.gov (United States)

    Rechnitz, Garry A.

    1975-01-01

    Describes the design of ion selective electrodes coupled with immobilized enzymes which operate either continuously or on drop-sized samples. Cites techniques for urea, L-phenylalanine and amygdalin. Micro size electrodes for use in single cells are discussed. (GH)

  19. Membrane Bioprobe Electrodes

    Science.gov (United States)

    Rechnitz, Garry A.

    1975-01-01

    Describes the design of ion selective electrodes coupled with immobilized enzymes which operate either continuously or on drop-sized samples. Cites techniques for urea, L-phenylalanine and amygdalin. Micro size electrodes for use in single cells are discussed. (GH)

  20. Optically Transparent Thin-Film Electrode Chip for Spectroelectrochemical Sensing

    Energy Technology Data Exchange (ETDEWEB)

    Branch, Shirmir D.; Lines, Amanda M.; Lynch, John A.; Bello, Job M.; Heineman, William R.; Bryan, Samuel A.

    2017-07-03

    The electrochemical and spectroelectrochemical applications of an optically transparent thin film electrode chip are investigated. The working electrode is composed of indium tin oxide (ITO); the counter and quasi-reference electrodes are composed of platinum. The stability of the platinum quasi-reference electrode is modified by coating it with a planar, solid state Ag/AgCl layer. The Ag/AgCl reference is characterized with scanning electron microscopy and energy-dispersive X-ray spectroscopy. Open circuit potential measurements indicate that the potential of the planar Ag/AgCl electrode varies a maximum of 20 mV over four days. Cyclic voltammetry measurements show that the electrode chip is comparable to a standard electrochemical cell. Randles-Sevcik analysis of 10 mM K3[Fe(CN)6] in 0.1 M KCl using the electrode chip shows a diffusion coefficient of 1.59 × 10-6 cm2/s, in comparison to the standard electrochemical cell value of 2.38 × 10-6 cm2/s. By using the electrode chip in an optically transparent thin layer electrode (OTTLE), the spectroelectrochemical modulation of [Ru(bpy)3]2+ florescence was demonstrated, achieving a detection limit of 36 nM.

  1. Nanoscale biomemory composed of recombinant azurin on a nanogap electrode.

    Science.gov (United States)

    Chung, Yong-Ho; Lee, Taek; Park, Hyung Ju; Yun, Wan Soo; Min, Junhong; Choi, Jeong-Woo

    2013-09-13

    We fabricate a nanoscale biomemory device composed of recombinant azurin on nanogap electrodes. For this, size-controllable nanogap electrodes are fabricated by photolithography, electron beam lithography, and surface catalyzed chemical deposition. Moreover, we investigate the effect of gap distance to optimize the size of electrodes for a biomemory device and explore the mechanism of electron transfer from immobilized protein to a nanogap counter-electrode. As the distance of the nanogap electrode is decreased in the nanoscale, the absolute current intensity decreases according to the distance decrement between the electrodes due to direct electron transfer, in contrast with the diffusion phenomenon of a micro-electrode. The biomemory function is achieved on the optimized nanogap electrode. These results demonstrate that the fabricated nanodevice composed of a nanogap electrode and biomaterials provides various advantages such as quantitative control of signals and exclusion of environmental effects such as noise. The proposed bioelectronics device, which could be mass-produced easily, could be applied to construct a nanoscale bioelectronics system composed of a single biomolecule.

  2. Effect of Electrode Configuration on Nitric Oxide Gas Sensor Behavior

    Directory of Open Access Journals (Sweden)

    Ling Cui

    2015-09-01

    Full Text Available The influence of electrode configuration on the impedancemetric response of nitric oxide (NO gas sensors was investigated for solid electrochemical cells [Au/yttria-stabilized zirconia (YSZ/Au]. Fabrication of the sensors was carried out at 1050 °C in order to establish a porous YSZ electrolyte that enabled gas diffusion. Two electrode configurations were studied where Au wire electrodes were either embedded within or wrapped around the YSZ electrolyte. The electrical response of the sensors was collected via impedance spectroscopy under various operating conditions where gas concentrations ranged from 0 to 100 ppm NO and 1%–18% O2 at temperatures varying from 600 to 700 °C. Gas diffusion appeared to be a rate-limiting mechanism in sensors where the electrode configuration resulted in longer diffusion pathways. The temperature dependence of the NO sensors studied was independent of the electrode configuration. Analysis of the impedance data, along with equivalent circuit modeling indicated the electrode configuration of the sensor effected gas and ionic transport pathways, capacitance behavior, and NO sensitivity.

  3. A semiconductor based electrode

    Energy Technology Data Exchange (ETDEWEB)

    Khamatani, A.; Kobayasi, K.

    1983-03-30

    The semiconductor electrode is submerged into an electrolyte which is held in the illuminated chamber. The other electrode is placed in a dark chamber connected with the channel to be illuminated, which has a partition in the form of a membrane. An electric current flows in the external circuit of the element with illumination of the first electrode. The illuminated electrode is covered with a thin film of a substance which is stable with the action of the electrolyte. The film is made of Si02, A1203, GaN or A1N. The protective coating makes it possible to use materials less stable than Ti02 in a rutile modification, but which have higher characteristics than the GaP, GaAs, CdS and InP, for making the electrode.

  4. Digital simulation of chronoamperometry at an electrode within a hemispherical polymer drop containing an enzyme: comparison of a hemispherical with a flat disk electrode

    DEFF Research Database (Denmark)

    Britz, Dieter; Strutwolf, Jörg

    2013-01-01

    Current-time and steady state current behaviour was simulated for the cases of a hemispherical and flat inlaid disk electrodes located under a hemispherical polymer drop containing an enzyme which converts a substrate diffusing into the drop into a product that is electroactive at the electrode. A...

  5. Electrochemical Impedance of a Battery Electrode with Anisotropic Active Particles

    CERN Document Server

    Song, J

    2013-01-01

    Electrochemical impedance spectra for battery electrodes are usually interpreted using models that assume isotropic active particles, having uniform current density and symmetric diffusivities. While this can be reasonable for amorphous or polycrystalline materials with randomly oriented grains, modern electrode materials increasingly consist of highly anisotropic, single-crystalline, nanoparticles, with different impedance characteristics. In this paper, analytical expressions are derived for the impedance of anisotropic particles with tensorial diffusivities and orientation-dependent surface reaction rates and capacitances. The resulting impedance spectrum contains clear signatures of the anisotropic material properties and aspect ratio, as well as statistical variations in any of these parameters.

  6. Redox Couples with Unequal Diffusion Coefficients: Effect on Redox Cycling

    NARCIS (Netherlands)

    Mampallil Augustine, Dileep; Mathwig, Klaus; Kang, Shuo; Lemay, Serge G.

    2013-01-01

    Redox cycling between two electrodes separated by a narrow gap allows dramatic amplification of the faradaic current. Unlike conventional electrochemistry at a single electrode, however, the mass-transport-limited current is controlled by the diffusion coefficient of both the reduced and oxidized fo

  7. Vaneless diffusers

    Science.gov (United States)

    Senoo, Y.

    The influence of vaneless diffusers on flow in centrifugal compressors, particularly on surge, is discussed. A vaneless diffuser can demonstrate stable operation in a wide flow range only if it is installed with a backward leaning blade impeller. The circumferential distortion of flow in the impeller disappears quickly in the vaneless diffuser. The axial distortion of flow at the diffuser inlet does not decay easily. In large specific speed compressors, flow out of the impeller is distorted axially. Pressure recovery of diffusers at distorted inlet flow is considerably improved by half guide vanes. The best height of the vanes is a little 1/2 diffuser width. In small specific speed compressors, flow out of the impeller is not much distorted and pressure recovery can be predicted with one-dimensional flow analysis. Wall friction loss is significant in narrow diffusers. The large pressure drop at a small flow rate can cause the positive gradient of the pressure-flow rate characteristic curve, which may cause surging.

  8. A survey of reference electrodes for high temperature waters; Oeversikt av referenselektroder i hoegtemperaturvatten

    Energy Technology Data Exchange (ETDEWEB)

    Molander, A.; Eriksson, Sture; Pein, K. [Studsvik Nuclear, Nykoeping (Sweden)

    2000-11-01

    , suggestions of variations of the conventional platinum electrode is given. Interesting variations are platinum electrodes with flowing electrolyte or quasi reversible hydrogen electrode. Development of silver chloride electrodes for extended lifetime can be done with e g a diffusion barrier to limit dilution. Also completely new types of reference electrodes are treated, as e g metal/metal oxide electrodes. These can be interesting but more development is required. Finally a survey of the measurements in BWR-PWR and CANDU reactors published in literature is given. In BWRs, American power plants (with electrodes from GE), Swedish power plants (with electrodes from Studsvik), Siemens and Toshiba have published measurements of larger extent. In PWRs, above all Ringhals and Siemens perform measurements today, even if a number of measurements through the years are published.

  9. Electroretinography in dogs using a fiber electrode prototype

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, A.L. [Clínica Veterinária Arca de Noé, Atibaia, SP (Brazil); Montiani-Ferreira, F. [Departamento de Medicina Veterinária, Universidade Federal do Paraná, Curitiba, PR (Brazil); Santos, V.R.; Salomão, S.R. [Departamento de Oftalmologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP (Brazil); Souza, C. [Department of Veterinary Clinical Sciences, Washington State University, Pullman, WA (United States); Berezovsky, A. [Departamento de Oftalmologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP (Brazil)

    2013-03-19

    We compared two electroretinography (ERG) electrodes in dogs using ERG standards of the International Society for Clinical Electrophysiology of Vision (ISCEV). Ten healthy Yorkshire terrier dogs (mean age, 2.80 ± 1.42 years; 6 females) weighing 5.20 ± 1.56 kg were evaluated using an ERG system for veterinary use. Dark- and light-adapted ERG responses were recorded using an ERG-Jet electrode and a fiber electrode prototype. The examinations were performed during 2 visits, 3 weeks apart. Both electrodes (ERG-Jet or fiber prototype) were used on each animal and the first eye to be recorded (OD × OS) was selected randomly. Three weeks later the examination was repeated on the same animal switching the type of electrode to be used that day and the first eye to be examined. The magnitude and waveform quality obtained with the two electrode types were similar for all ERG responses. ERG amplitudes and implicit times obtained from dogs using the fiber electrode prototype were comparable to those obtained with the ERG-Jet electrode for rod, maximal rod-cone summed, cone, and 30-Hz flicker responses. The fiber electrode prototype is a low-cost device, available as an alternative instrument for clinical veterinary ERG recording for retinal function assessment.

  10. Continuous separation of submicron particles using Angled electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Yunus, Nurul A Md; Green, Nicolas G [Nano Research Group, School of Electronics and Computer Science, University of Southampton, SO17 1BJ (United Kingdom)], E-mail: ng2@ecs.soton.ac.uk

    2008-12-01

    Dielectrophoretic separation of particles is achieved by the generation of electric forces on the particles by non-uniform electric fields. This paper presents a technique based on negative dielectrophoresis in a novel design of electrode array for the non-contact separation of polarisable particles. Angled electrodes are used to generate a lateral force in a microfluidic channel separating a mixed stream of particles into distinct streams of constituent components and achieving a high degree of spatial separation.

  11. EFFECTS OF TEMPERATURE AND CONTAMINATION ON MPCMS ELECTRODES IN 241-AY-101 AND 241-AN-107 TANK WASTE SIMULANTS

    Energy Technology Data Exchange (ETDEWEB)

    CATO DM; DAHL MM; PHILO GL; EDGEMON GL; BELL DR.JLS; MOORE CG

    2010-03-26

    This report documents the results of tests designed to characterize the relationship between temperature and the measured potential of electrodes installed on multi-probe corrosion monitoring systems in waste tanks. This report also documents the results of tests designed to demonstrate the impact of liquid in-leakage into electrode bodies as well as the contamination of primary reference electrodes by diffusion through the electrode tip.

  12. Electrodes for solid state devices

    Science.gov (United States)

    Bickler, D. B. (Inventor)

    1983-01-01

    The invention relates to coated metal powders and to dispersions of such powders in liquid vehicles forming screenable, sinterable pastes for use in forming electrodes on photovoltaic devices. The primary nickel or copper metal particles are provided with a carrier of lower melting sintering metals such as 1-20% by weight, of a non-oxidizing metal such as lead or tin. The powdered metal systems operate on the basis of fusing together by way of eutectic alloying. As the paste is heated during firing the organic binder is first vaporized. An eutectic of the base metal (copper) and coating (tin) forms at the intersections of the base metal grains. This eutectic dissolves the grains and as the temperature is raised above the eutectic temperature, more of the base metal is dissolved. While the temperature is held at the higher value, the much smaller amount of sintering metal disappears as the eutectic dissolves and diffuses into the base metal until the composition of the eutectic is so enriched with base metal that it no longer has the eutectic properties and it solidifies. In this high temperature solidification, the base metal grains became thoroughly alloyed together and will not separate at the eutectic temperature (a lower temperature than their solidification by diffusion).

  13. Roles of Bulk and Surface Chemistry in the Oxygen Exchange Kinetics and Related Properties of Mixed Conducting Perovskite Oxide Electrodes

    Directory of Open Access Journals (Sweden)

    Nicola H. Perry

    2016-10-01

    Full Text Available Mixed conducting perovskite oxides and related structures serving as electrodes for electrochemical oxygen incorporation and evolution in solid oxide fuel and electrolysis cells, respectively, play a significant role in determining the cell efficiency and lifetime. Desired improvements in catalytic activity for rapid surface oxygen exchange, fast bulk transport (electronic and ionic, and thermo-chemo-mechanical stability of oxygen electrodes will require increased understanding of the impact of both bulk and surface chemistry on these properties. This review highlights selected work at the International Institute for Carbon-Neutral Energy Research (I2CNER, Kyushu University, set in the context of work in the broader community, aiming to characterize and understand relationships between bulk and surface composition and oxygen electrode performance. Insights into aspects of bulk point defect chemistry, electronic structure, crystal structure, and cation choice that impact carrier concentrations and mobilities, surface exchange kinetics, and chemical expansion coefficients are emerging. At the same time, an understanding of the relationship between bulk and surface chemistry is being developed that may assist design of electrodes with more robust surface chemistries, e.g., impurity tolerance or limited surface segregation. Ion scattering techniques (e.g., secondary ion mass spectrometry, SIMS, or low energy ion scattering spectroscopy, LEIS with high surface sensitivity and increasing lateral resolution are proving useful for measuring surface exchange kinetics, diffusivity, and corresponding outer monolayer chemistry of electrodes exposed to typical operating conditions. Beyond consideration of chemical composition, the use of strain and/or a high density of active interfaces also show promise for enhancing performance.

  14. Note: electrode polarization of Galinstan electrodes for liquid impedance spectroscopy.

    Science.gov (United States)

    Mellor, Brett L; Kellis, Nathan A; Mazzeo, Brian A

    2011-04-01

    Electrode polarization is a significant obstacle in the impedance measurements of ionic liquids. An atomically smooth electrode surface could potentially reduce unwanted impedance contributions from electrode polarization. Liquid metal electrodes were formed by adhering Galinstan to acrylic plates in a parallel-plate capacitor arrangement. Electrode polarization was compared to a similar cell with stainless steel electrodes. The impedance of salt and protein solutions (β-lactoglobulin) was measured from 40 Hz to 110 MHz. Because of oxide layer formation, the performance of the Galinstan electrode is significantly different than the theoretical ideal.

  15. Porous Electrode Studies.

    Science.gov (United States)

    1980-07-01

    representation and analysis for their observed current distributions. Simonsson won the young author’s award of the Electrochemical Society for his paper...and T. Katan, Proc. Symp. Energy Storage and Conversion, the Electrochemical Society 77-6, 770 (1977) The optimum thickness of porous electrodes is...Chloride Electrodes; Surface Morphology on Charging and Dis- charging," T. Katan, S. Szpak, and D. N. Bennion, The Electrochemical Society , 143rd National

  16. Tennis Elbow (Lateral Epicondylitis)

    Science.gov (United States)

    .org Tennis Elbow (Lateral Epicondylitis) Page ( 1 ) Tennis elbow, or lateral epicondyliti s, is a painful condition of the elbow caused by overuse. Not surprisingly, playing tennis or other racquet sports can cause ...

  17. Techniques of Electrode Fabrication

    Science.gov (United States)

    Guo, Liang; Li, Xinyong; Chen, Guohua

    Electrochemical applications using many kinds of electrode materials as an advanced oxidation/reduction technique have been a focus of research by a number of groups during the last two decades. The electrochemical approach has been adopted successfully to develop various environmental applications, mainly including water and wastewater treatment, aqueous system monitoring, and solid surface analysis. In this chapter, a number of methods for the fabrication of film-structured electrode materials were selectively reviewed. Firstly, the thermal decomposition method is briefly described, followed by introducing chemical vapor deposition (CVD) strategy. Especially, much attention was focused on introducing the methods to produce diamond novel film electrode owing to its unique physical and chemical properties. The principle and influence factors of hot filament CVD and plasma enhanced CVD preparation were interpreted by refereeing recent reports. Finally, recent developments that address electro-oxidation/reduction issues and novel electrodes such as nano-electrode and boron-doped diamond electrode (BDD) are presented in the overview.

  18. A strategy for selective detection based on interferent depleting and redox cycling using the plane-recessed microdisk array electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Feng [State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Yan Jiawei, E-mail: jwyan@xmu.edu.cn [State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Lu Miao [Pen-Tung Sah Micro-Nano Technology Research Center, Xiamen University, Xiamen, Fujian 361005 (China); Zhou Yongliang; Yang Yang; Mao Bingwei [State Key Laboratory for Physical Chemistry of Solid Surfaces and Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China)

    2011-10-01

    Highlights: > A novel strategy based on a combination of interferent depleting and redox cycling is proposed for the plane-recessed microdisk array electrodes. > The strategy break up the restriction of selectively detecting a species that exhibits reversible reaction in a mixture with one that exhibits an irreversible reaction. > The electrodes enhance the current signal by redox cycling. > The electrodes can work regardless of the reversibility of interfering species. - Abstract: The fabrication, characterization and application of the plane-recessed microdisk array electrodes for selective detection are demonstrated. The electrodes, fabricated by lithographic microfabrication technology, are composed of a planar film electrode and a 32 x 32 recessed microdisk array electrode. Different from commonly used redox cycling operating mode for array configurations such as interdigitated array electrodes, a novel strategy based on a combination of interferent depleting and redox cycling is proposed for the electrodes with an appropriate configuration. The planar film electrode (the plane electrode) is used to deplete the interferent in the diffusion layer. The recessed microdisk array electrode (the microdisk array), locating within the diffusion layer of the plane electrode, works for detecting the target analyte in the interferent-depleted diffusion layer. In addition, the microdisk array overcomes the disadvantage of low current signal for a single microelectrode. Moreover, the current signal of the target analyte that undergoes reversible electron transfer can be enhanced due to the redox cycling between the plane electrode and the microdisk array. Based on the above working principle, the plane-recessed microdisk array electrodes break up the restriction of selectively detecting a species that exhibits reversible reaction in a mixture with one that exhibits an irreversible reaction, which is a limitation of single redox cycling operating mode. The advantages of the

  19. ELECTRIC ARC WELDING DEPOSITION OF METALLIC SURFACES BY VIBRATING ELECTRODE IN PROTECTIVE GAS MEDIUM

    Directory of Open Access Journals (Sweden)

    N. Spiridonov

    2013-01-01

    Full Text Available The paper presents methods for obtaining qualitative metallic surfaces by electric arc welding deposition while using consumable electrode in a protective gas medium and executing regularized drop transfer of electrode metal. The drop transfer efficiency of electrode metal and productivity of welding deposition are significantly increased due to excitation of lateral vibrations in the consumable electrode with preset amplitude. The paper describes a method and a device for welding deposition of metallic surfaces by vibrating  electrode where vibrations are excited by ultrasound.

  20. Sensor employing internal reference electrode

    DEFF Research Database (Denmark)

    2013-01-01

    The present invention concerns a novel internal reference electrode as well as a novel sensing electrode for an improved internal reference oxygen sensor and the sensor employing same.......The present invention concerns a novel internal reference electrode as well as a novel sensing electrode for an improved internal reference oxygen sensor and the sensor employing same....

  1. Monte Carlo analysis of a lateral IBIC experiment on a 4H-SiC Schottky diode

    Energy Technology Data Exchange (ETDEWEB)

    Olivero, P. [Experimental Physics Dept./NIS Excellence Centre, University of Torino, and INFN-Sez. di Torino via P. Giuria 1, 10125 Torino (Italy); Ruder Boskovic Institute, Bijenicka 54, P.O. Box 180, 10002 Zagreb (Croatia); Forneris, J.; Gamarra, P. [Experimental Physics Dept./NIS Excellence Centre, University of Torino, and INFN-Sez. di Torino via P. Giuria 1, 10125 Torino (Italy); Jaksic, M. [Ruder Boskovic Institute, Bijenicka 54, P.O. Box 180, 10002 Zagreb (Croatia); Lo Giudice, A.; Manfredotti, C. [Experimental Physics Dept./NIS Excellence Centre, University of Torino, and INFN-Sez. di Torino via P. Giuria 1, 10125 Torino (Italy); Pastuovic, Z.; Skukan, N. [Ruder Boskovic Institute, Bijenicka 54, P.O. Box 180, 10002 Zagreb (Croatia); Vittone, E., E-mail: ettore.vittone@unito.it [Experimental Physics Dept./NIS Excellence Centre, University of Torino, and INFN-Sez. di Torino via P. Giuria 1, 10125 Torino (Italy)

    2011-10-15

    The transport properties of a 4H-SiC Schottky diode have been investigated by the ion beam induced charge (IBIC) technique in lateral geometry through the analysis of the charge collection efficiency (CCE) profile at a fixed applied reverse bias voltage. The cross section of the sample orthogonal to the electrodes was irradiated by a rarefied 4 MeV proton microbeam and the charge pulses have been recorded as function of incident proton position with a spatial resolution of 2 {mu}m. The CCE profile shows a broad plateau with CCE values close to 100% occurring at the depletion layer, whereas in the neutral region, the exponentially decreasing profile indicates the dominant role played by the diffusion transport mechanism. Mapping of charge pulses was accomplished by a novel computational approach, which consists in mapping the Gunn's weighting potential by solving the electrostatic problem by finite element method and hence evaluating the induced charge at the sensing electrode by a Monte Carlo method. The combination of these two computational methods enabled an exhaustive interpretation of the experimental profiles and allowed an accurate evaluation both of the electrical characteristics of the active region (e.g. electric field profiles) and of basic transport parameters (i.e. diffusion length and minority carrier lifetime).

  2. Monte Carlo analysis of a lateral IBIC experiment on a 4H-SiC Schottky diode

    Science.gov (United States)

    Olivero, P.; Forneris, J.; Gamarra, P.; Jakšić, M.; Giudice, A. Lo; Manfredotti, C.; Pastuović, Ž.; Skukan, N.; Vittone, E.

    2011-10-01

    The transport properties of a 4H-SiC Schottky diode have been investigated by the ion beam induced charge (IBIC) technique in lateral geometry through the analysis of the charge collection efficiency (CCE) profile at a fixed applied reverse bias voltage. The cross section of the sample orthogonal to the electrodes was irradiated by a rarefied 4 MeV proton microbeam and the charge pulses have been recorded as function of incident proton position with a spatial resolution of 2 μm. The CCE profile shows a broad plateau with CCE values close to 100% occurring at the depletion layer, whereas in the neutral region, the exponentially decreasing profile indicates the dominant role played by the diffusion transport mechanism. Mapping of charge pulses was accomplished by a novel computational approach, which consists in mapping the Gunn's weighting potential by solving the electrostatic problem by finite element method and hence evaluating the induced charge at the sensing electrode by a Monte Carlo method. The combination of these two computational methods enabled an exhaustive interpretation of the experimental profiles and allowed an accurate evaluation both of the electrical characteristics of the active region (e.g. electric field profiles) and of basic transport parameters (i.e. diffusion length and minority carrier lifetime).

  3. Millisecond dynamics of thermal expansion of mechanically controllable break junction electrodes studied in the tunneling regime

    Science.gov (United States)

    Kolesnychenko, O. Yu.; Toonen, A. J.; Shklyarevskii, O. I.; van Kempen, H.

    2001-10-01

    The thermal expansion dynamics of W, Pt-Ir, and Au mechanically controllable break junction electrodes was studied in the millisecond range. By measuring a transient tunnel current as a function of time, we found that, at low temperatures, the electrode elongation Δs˜t1/2 due to the large values of thermal diffusivity of metals. The magnitude of Δs varies in direct proportion to the power P dissipated in the electrodes.

  4. Diffusional protection of electrode surfaces using regular arrays of immobilised droplets: overcoming interferences in electroanalysis.

    Science.gov (United States)

    Simm, Andrew O; Ordeig, Olga; Del Campo, Javier; Muñoz, Francesc Xavier; Compton, Richard G

    2006-09-01

    Regular arrays of ca. micron sized droplets on a gold electrode surface can block diffusion to the electrode surface of one metal ion (which binds with the material in the droplet) whilst having no significant effect on another (which does not), so allowing interference effects in electroanalysis to be eliminated.

  5. Electrochemistry of ABTS at Glassy Carbon Electrodes

    Institute of Scientific and Technical Information of China (English)

    Han Zeng; Zhi-qiang Tang; Ling-wen Liao; Jing Kang; Yan-xia Chen

    2011-01-01

    The electrochemical and the mass transport behavior of ABTS2-/ABTS- (2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate)) redox couple at glassy carbon electrode (GCE) in phosphate buffer solution (PBS,pH=4.4) is studied in detail by cyclic voltammetry combined with rotating disk electrode system.From the i-E curves recorded at different electrode rotating rate,rate constant,and transfer coefficient for ABTS 2-(≒)ABTS-+e reaction at GCE electrode and the diffusion coefficient of ABTS2- in PBS are estimated to be 4.6× 10-3 cm/s,0.28,and 4.4× 10-6 cm2/s,respectively.The transfer coefficient with a value of ca.0.28 differs largely from the value of 0.5 that is always assumed in the literature.The origins for the difference of the rate constant determined and the challenges for estimating the standard rate constant are discussed.The performance for such ABTS2- mediated bio-cathode toward oxygen reduction reaction is discussed according to the over-potential drop as well as current output limit associated with the charge transfer kinetics of ABTS2- (≒)ABTS- +e redox reaction and/or the mass transport effect.

  6. Diffused Religion and Prayer

    Directory of Open Access Journals (Sweden)

    Roberto Cipriani

    2011-06-01

    Full Text Available It is quite likely that the origins of prayer are to be found in ancient mourning and bereavement rites. Primeval ritual prayer was codified and handed down socially to become a deep-rooted feature of people’s cultural behavior, so much so, that it may surface again several years later, in the face of death, danger, need, even in the case of relapse from faith and religious practice. Modes of prayer depend on religious experience, on relations between personal prayer and political action, between prayer and forgiveness, and between prayer and approaches to religions. Various forms of prayer exist, from the covert-hidden to the overt-manifest kind. How can they be investigated? How can one, for instance, explore mental prayer? These issues regard the canon of diffused religion and, therefore, of diffused prayer.

  7. Probing Electrode Heterogeneity Using Fourier-Transformed Alternating Current Voltammetry: Application to a Dual-Electrode Configuration.

    Science.gov (United States)

    Tan, Sze-Yin; Unwin, Patrick R; Macpherson, Julie V; Zhang, Jie; Bond, Alan M

    2017-03-07

    Quantitative studies of electron transfer processes at electrode/electrolyte interfaces, originally developed for homogeneous liquid mercury or metallic electrodes, are difficult to adapt to the spatially heterogeneous nanostructured electrode materials that are now commonly used in modern electrochemistry. In this study, the impact of surface heterogeneity on Fourier-transformed alternating current voltammetry (FTACV) has been investigated theoretically under the simplest possible conditions where no overlap of diffusion layers occurs and where numerical simulations based on a 1D diffusion model are sufficient to describe the mass transport problem. Experimental data that meet these requirements can be obtained with the aqueous [Ru(NH3)6](3+/2+) redox process at a dual-electrode system comprised of electrically coupled but well-separated glassy carbon (GC) and boron-doped diamond (BDD) electrodes. Simulated and experimental FTACV data obtained with this electrode configuration, and where distinctly different heterogeneous charge transfer rate constants (k(0) values) apply at the individual GC and BDD electrode surfaces, are in excellent agreement. Principally, because of the far greater dependence of the AC current magnitude on k(0), it is straightforward with the FTACV method to resolve electrochemical heterogeneities that are ∼1-2 orders of magnitude apart, as applies in the [Ru(NH3)6](3+/2+) dual-electrode configuration experiments, without prior knowledge of the individual kinetic parameters (k(0)1 and k(0)2) or the electrode size ratio (θ1:θ2). In direct current voltammetry, a difference in k(0) of >3 orders of magnitude is required to make this distinction.

  8. Simulation of nanostructured electrodes for polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Rao, Sanjeev M.; Xing, Yangchuan

    Aligned carbon nanotubes (CNTs) with Pt uniformly deposited on them are being considered in fabricating the catalyst layer of polymer electrolyte membrane (PEM) fuel cell electrodes. When coated with a proton conducting polymer (e.g., Nafion) on the Pt/CNTs, each Pt/CNT acts as a nanoelectrode and a collection of such nanoelectrodes constitutes the proposed nanostructured electrodes. Computer modeling was performed for the cathode side, in which both multicomponent and Knudsen diffusion were taken into account. The effect of the nanoelectrode lengths was also studied with catalyst layer thicknesses of 2, 4, 6, and 10 μm. It was observed that shorter lengths produce better electrode performance due to lower diffusion barriers and better catalyst utilization. The effect of spacing between the nanoelectrodes was studied. Simulation results showed the need to have sufficiently large gas pores, i.e., large spacing, for good oxygen transport. However, this is at the cost of obtaining large electrode currents due to reduction of the number of nanoelectrodes per unit geometrical area of the nanostructured electrode. An optimization of the nanostructured electrodes was obtained when the spacing was at about 400 nm that produced the best limiting current density.

  9. Diffuse scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kostorz, G. [Eidgenoessische Technische Hochschule, Angewandte Physik, Zurich (Switzerland)

    1996-12-31

    While Bragg scattering is characteristic for the average structure of crystals, static local deviations from the average lattice lead to diffuse elastic scattering around and between Bragg peaks. This scattering thus contains information on the occupation of lattice sites by different atomic species and on static local displacements, even in a macroscopically homogeneous crystalline sample. The various diffuse scattering effects, including those around the incident beam (small-angle scattering), are introduced and illustrated by typical results obtained for some Ni alloys. (author) 7 figs., 41 refs.

  10. The new mid-scala electrode array: a radiologic and histologic study in human temporal bones.

    Science.gov (United States)

    Hassepass, Frederike; Bulla, Stefan; Maier, Wolfgang; Laszig, Roland; Arndt, Susan; Beck, Rainer; Traser, Lousia; Aschendorff, Antje

    2014-09-01

    To analyze the quality of insertion of the newly developed midscala (MS) electrode, which targets a midscalar electrode position to reduce the risk of trauma to the lateral wall and the modiolus. Modern cochlear implant surgery aims for a safe intracochlear placement of electrode arrays with an ongoing debate regarding cochleostomy or round window (RW) insertion and the use of lateral wall or perimodiolar electrode placement. Intracochlear trauma after insertion of different electrodes depends on insertion mode and electrode design and may result in trauma to the delicate structures of the cochlear. We performed a temporal bone (TB) trial with insertion of the MS electrode in n = 20 TB's after a mastoidectomy and posterior tympanotomy. Insertion was performed either via the RW or a cochleostomy. Electrode positioning, length of insertion, and angle of insertion were analyzed with rotational tomography (RT). TBs were histologically analyzed. Results of RT and histology were compared. Scala tympani (ST) insertion could be accomplished reliably by both RW and via a cochleostomy approach. In 20 TBs, 1 scala vestibuli insertion, 1 incomplete (ST), and 1 elevation of basilar membrane were depicted. No trauma was found in 94.7% of all ST insertions. RT allowed determination of the intracochlear electrode position, which was specified by histologic sectioning. The new MS electrode seems to fulfill reliable atraumatic intracochlear placement via RW and cochleostomy approaches. RT is available for evaluation of intracochlear electrode position, serving as a potential quality control instrument in human implantation.

  11. Electrochemical investigation of NO at single-wall carbon nanotubes modified electrodes

    Indian Academy of Sciences (India)

    Tingliang Xia; Hongmei Bi; Keying Shi

    2010-05-01

    The NO electro-oxidation was investigated at various single-wall carbon nanotubes (SWCNTs) modified electrodes by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Compared with the glassy carbon electrode, the SWCNTs modified electrodes possess higher electro-catalytic activity to NO electro-oxidation. CV results indicate that the peak current density of NO electro-oxidation at the SWCNT-COOH (SWCNTs with carboxyl groups) modified electrode is the highest and the peak potential is the most negative among the four kinds of electrodes. EIS indicates that the charge transfer resistance of NO electro-oxidation at the SWCNT-COOH modified electrode is the least. The determined factors (charge transfer and mass transfer of diffusion) of NO electro-oxidation are different in varied potential region. The mechanism of NO electro-oxidation reaction at the SWCNTs modified electrodes is also discussed.

  12. Lateral ink mobility and fringe field effects across the porous matrix of an electrophoretic display

    Science.gov (United States)

    Li Tsui, Kelly; Ahumada, Manuel; Bryning, Mateusz; Hartono, Michelle; Lee, Sang-Joon J.

    2013-03-01

    This investigation studies fringe field between laterally adjacent electrodes in a reverse-emulsion electrophoretic display (REED). The display consists of a nanodroplet ink and a porous matrix that serves as the "paper" between planar electrodes. One relative advantage of this type of electronic paper display is that it can be produced with lowcost materials and manufacturing processes. A concern for image resolution, however, is the fringe field effect that occurs in the gaps between neighboring electrodes. Ideally the dye-containing nanodroplets in the ink move in a direction that is strictly perpendicular to the opposing pairs of electrodes. However, nanodroplet saturation and potential gradients from neighboring electrodes may result in lateral displacement of the nanodroplets as well. Accordingly, this study examines how fringe field between neighboring electrodes is affected by lateral spacing and applied voltage. Transient and steady-state effects were studied by fabricating and testing devices that were patterned with different lateral spacing between electrodes, and switching under different voltage levels. Relative luminance was extracted from digital microscope images, captured in the vicinity between neighboring electrodes. Measurements were recorded for electrode spacing of 20 μm, 40 μm, 60 μm, and 80 μm with devices switched at ±1.5 V and ±2.5 V. Gradients in luminance overlapped at lateral distances below 60 μm, and became distinct for left and right electrodes spaced by at least 80 μm. Higher applied voltage resulted in steeper transition between light and dark states, but exhibited distortion at electrode edges.

  13. Relativistic diffusion.

    Science.gov (United States)

    Haba, Z

    2009-02-01

    We discuss relativistic diffusion in proper time in the approach of Schay (Ph.D. thesis, Princeton University, Princeton, NJ, 1961) and Dudley [Ark. Mat. 6, 241 (1965)]. We derive (Langevin) stochastic differential equations in various coordinates. We show that in some coordinates the stochastic differential equations become linear. We obtain momentum probability distribution in an explicit form. We discuss a relativistic particle diffusing in an external electromagnetic field. We solve the Langevin equations in the case of parallel electric and magnetic fields. We derive a kinetic equation for the evolution of the probability distribution. We discuss drag terms leading to an equilibrium distribution. The relativistic analog of the Ornstein-Uhlenbeck process is not unique. We show that if the drag comes from a diffusion approximation to the master equation then its form is strongly restricted. The drag leading to the Tsallis equilibrium distribution satisfies this restriction whereas the one of the Jüttner distribution does not. We show that any function of the relativistic energy can be the equilibrium distribution for a particle in a static electric field. A preliminary study of the time evolution with friction is presented. It is shown that the problem is equivalent to quantum mechanics of a particle moving on a hyperboloid with a potential determined by the drag. A relation to diffusions appearing in heavy ion collisions is briefly discussed.

  14. Composite carbon foam electrode

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

    1997-05-06

    Carbon aerogels used as a binder for granulated materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy. 1 fig.

  15. Composite carbon foam electrode

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, Steven T. (San Leandro, CA); Pekala, Richard W. (Pleasant Hill, CA); Kaschmitter, James L. (Pleasanton, CA)

    1997-01-01

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivty and power to system energy.

  16. Ion-selective electrodes

    CERN Document Server

    Mikhelson, Konstantin N

    2013-01-01

    Ion-selective electrodes (ISEs) have a wide range of applications in clinical, environmental, food and pharmaceutical analysis as well as further uses in chemistry and life sciences. Based on his profound experience as a researcher in ISEs and a course instructor, the author summarizes current knowledge for advanced teaching and training purposes with a particular focus on ionophore-based ISEs. Coverage includes the basics of measuring with ISEs, essential membrane potential theory and a comprehensive overview of the various classes of ion-selective electrodes. The principles of constructing I

  17. Single Electrode Heat Effects

    DEFF Research Database (Denmark)

    Jacobsen, Torben; Broers, G. H. J.

    1977-01-01

    SP, of theelectrode reaction. eta is the overvoltage at the electrode. This equation is appliedto a high temperature carbonate fuel cell. It is shown that the Peltier entropyterm by far exceeds the heat production due to the irreversible losses, and thatthe main part of heat evolved at the cathode is reabsorbed......The heat evolution at a single irreversibly working electrode is treated onthe basis of the Brønsted heat principle. The resulting equation is analogous to the expression for the total heat evolution in a galvanic cellwith the exception that –DeltaS is substituted by the Peltier entropy, Delta...

  18. Diffusion in membranes: Toward a two-dimensional diffusion map

    Directory of Open Access Journals (Sweden)

    Toppozini Laura

    2015-01-01

    Full Text Available For decades, quasi-elastic neutron scattering has been the prime tool for studying molecular diffusion in membranes over relevant nanometer distances. These experiments are essential to our current understanding of molecular dynamics of lipids, proteins and membrane-active molecules. Recently, we presented experimental evidence from X-ray diffraction and quasi-elastic neutron scattering demonstrating that ethanol enhances the permeability of membranes. At the QENS 2014/WINS 2014 conference we presented a novel technique to measure diffusion across membranes employing 2-dimensional quasi-elastic neutron scattering. We present results from our preliminary analysis of an experiment on the cold neutron multi-chopper spectrometer LET at ISIS, where we studied the self-diffusion of water molecules along lipid membranes and have the possibility of studying the diffusion in membranes. By preparing highly oriented membrane stacks and aligning them horizontally in the spectrometer, our aim is to distinguish between lateral and transmembrane diffusion. Diffusion may also be measured at different locations in the membranes, such as the water layer and the hydrocarbon membrane core. With a complete analysis of the data, 2-dimensional mapping will enable us to determine diffusion channels of water and ethanol molecules to quantitatively determine nanoscale membrane permeability.

  19. Reference Electrodes in Metal Corrosion

    Directory of Open Access Journals (Sweden)

    S. Szabó

    2010-01-01

    Full Text Available With especial regard to hydrogen electrode, the theoretical fundamentals of electrode potential, the most important reference electrodes and the electrode potential measurement have been discussed. In the case of the hydrogen electrode, it have been emphasised that there is no equilibrium between the hydrogen molecule (H2 and the hydrogen (H+, hydronium (H3O+ ion in the absence of a suitable catalyst. Taking into account the practical aspects as well, the theorectical basis of working of hydrogen, copper-copper sulphate, mercury-mercurous halide, silver-silver halide, metal-metal oxide, metal-metal sulphate and “Thalamid” electrodes, has been discussed.

  20. On the impedance of galvanic cells—XVI The impedance of the dropping mercury electrode in aqueous 1 M KCl with K+ discharge

    NARCIS (Netherlands)

    Sluyters-Rehbach, M.; Sluyters, J.H.

    1966-01-01

    The discharge of K+ ions at the dropping mercury electrode (dme) in 1 M KCl solution at 25°C has been studied by means of analysis of the electrode impedance at different frequencies, using the complex plane method. It is shown that the electrode reaction is almost entirely diffusion-controlled, but

  1. Virtual electrodes for high-density electrode arrays

    Energy Technology Data Exchange (ETDEWEB)

    Cela, Carlos Jose; Lazzi, Gianluca

    2017-05-23

    The present embodiments are directed to implantable electrode arrays having virtual electrodes. The virtual electrodes may improve the resolution of the implantable electrode array without the burden of corresponding complexity of electronic circuitry and wiring. In a particular embodiment, a virtual electrode may include one or more passive elements to help steer current to a specific location between the active electrodes. For example, a passive element may be a metalized layer on a substrate that is adjacent to, but not directly connected to an active electrode. In certain embodiments, an active electrode may be directly coupled to a power source via a conductive connection. Beneficially, the passive elements may help to increase the overall resolution of the implantable array by providing additional stimulation points without requiring additional wiring or driver circuitry for the passive elements.

  2. Robot-assisted placement of depth electrodes along the long Axis of the amygdalohippocampal complex

    Directory of Open Access Journals (Sweden)

    Alvin Y. Chan

    2016-12-01

    Conclusions: We have developed the Robot-Assisted Lateral Transoccipital Approach (RALTA, which is an advantageous technique for placing bilateral amygdalohippocampal depth electrodes using robotic guidance. Benefits of this technique include fewer electrodes required per patient and ease of positioning compared with seated or prone positioning.

  3. Spin Injection, Transport, and Detection at Room Temperature in a Lateral Spin Transport Device with Co2FeAl0.5Si0.5/n-GaAs Schottky Tunnel Junctions

    Science.gov (United States)

    Saito, Tatsuya; Tezuka, Nobuki; Matsuura, Masashi; Sugimoto, Satoshi

    2013-10-01

    We observed spin-valve signals and Hanle signals in four-terminal nonlocal measurements on a lateral spin transport device with Co2FeAl0.5Si0.5(CFAS)/n-GaAs Schottky tunnel junctions. The estimated spin injection/detection efficiency was 0.06 at 4.2 K, which is larger than those of the devices with Fe and CoFe electrodes [Nature Physics 3 (2007) 197 and Appl. Phys. Lett. 99 (2011) 082108]. The spin diffusion length estimated from Hanle signals was consistent with the gap length dependency of the spin-valve signals. Furthermore, the spin-valve signals were observed at up to 290 K. This is the first demonstration of detecting spin accumulation in semiconductor with full-Heusler alloys electrodes at room temperature.

  4. Submicron electrode gaps fabricated by gold electrodeposition at interdigitated electrodes

    NARCIS (Netherlands)

    Megen, M.J.J; Olthuis, W.; Berg, van den A.

    2014-01-01

    Electrodes with submicron gaps are desired for achieving high amplification redox cycling sensors. In this contribution we report the use of electrodeposition of gold in order to decrease the inter-electrode spacing at interdigitated electrodes. Using this method submicron spacings can be obtained w

  5. Single Electrode Heat Effects

    DEFF Research Database (Denmark)

    Jacobsen, Torben; Broers, G. H. J.

    1977-01-01

    for the oxygen electrode reaction is estimatedfrom thermodynamic data and reasonable agreement with the experimentalresults is found. It is concluded that the main contribution to the Peltierentropy arises from the transition from gaseous to liquid state, whereas thetransfer entropies of the ionic species...

  6. Dry EEG Electrodes

    Directory of Open Access Journals (Sweden)

    M. A. Lopez-Gordo

    2014-07-01

    Full Text Available Electroencephalography (EEG emerged in the second decade of the 20th century as a technique for recording the neurophysiological response. Since then, there has been little variation in the physical principles that sustain the signal acquisition probes, otherwise called electrodes. Currently, new advances in technology have brought new unexpected fields of applications apart from the clinical, for which new aspects such as usability and gel-free operation are first order priorities. Thanks to new advances in materials and integrated electronic systems technologies, a new generation of dry electrodes has been developed to fulfill the need. In this manuscript, we review current approaches to develop dry EEG electrodes for clinical and other applications, including information about measurement methods and evaluation reports. We conclude that, although a broad and non-homogeneous diversity of approaches has been evaluated without a consensus in procedures and methodology, their performances are not far from those obtained with wet electrodes, which are considered the gold standard, thus enabling the former to be a useful tool in a variety of novel applications.

  7. Effect of preparation method of metal hydride electrode on efficiency of hydrogen electrosorption process

    Energy Technology Data Exchange (ETDEWEB)

    Giza, Krystyna [Czestochowa University of Technology (Poland). Faculty of Production Engineering and Materials Technology; Drulis, Henryk [Trzebiatowski Institute of Low Temperatures and Structure Research PAS, Wroclaw (Poland)

    2016-02-15

    The preparation of negative electrodes for nickel-metal hydride batteries using LaNi{sub 4.3}Co{sub 0.4}Al{sub 0.3} alloy is presented. The constant current discharge technique is employed to determine the discharge capacity, the exchange current density and the hydrogen diffusion coefficient of the studied electrodes. The electrochemical performance of metal hydride electrode is strongly affected by preparation conditions. The results are compared and the advantages and disadvantages of preparation methods of the electrodes are also discussed.

  8. Electrical polymerization of a tetrazole polymer-modified electrode and its catalytic reaction toward dopamine

    Science.gov (United States)

    Hsieh, Mu-Tao; Whang, Thou-Jen

    2017-02-01

    A conducting polymer-modified electrode was proposed in this article, which was fabricated by electropolymerization of 5-amino-1H-tetrazole (ATet) on a glassy carbon electrode. Electrochemical studies such as differential pulse voltammetry and chronoamperometry were performed for the evaluation of the rate constant of the catalytic reaction, the diffusion coefficient of the analyte dopamine, and the linear dynamic range of the analyte determination. The film modified electrode has superior resolving power in quantitative determination from the mixture of analytes and it was found to be an efficient functionalized electrode for its sensitivity and selectivity toward the analyte of interest.

  9. On effective transport coefficients in PEM fuel cell electrodes: Anisotropy of the porous transport layers

    Science.gov (United States)

    Pharoah, J. G.; Karan, K.; Sun, W.

    This paper reviews the approach taken in the literature to model the effective transport coefficients - mass diffusivity, electrical conductivity, thermal conductivity and hydraulic permeability - of carbon-fibre based porous electrode of polymer electrolyte membrane fuel cells (PEMFCs). It is concluded that current PEMFC model do not account for the inherent anisotropic microstructure of the fibrous electrodes. Simulations using a 2-D PEMFC cathode model show that neglecting the anisotropic nature and associated transport coefficients of the porous electrodes significantly influences both the nature and the magnitude of the model predictions. This emphasizes the need to appropriately characterize the relevant anisotropic properties of the fibrous electrode.

  10. Silicon drift detector with reduced lateral diffusion: experimental results

    CERN Document Server

    Sonsky, J; Huizenga, John R; Hollander, R W; Eijk, C W E; Sarro, P M

    2000-01-01

    In a standard multi-anode silicon drift detector electron cloud broadening during the drifting towards the anode pixels deteriorates the energy and position resolution. This makes the detector less applicable for detection of low-energy X-rays. The signal charge sharing between several anodes can be eliminated by introducing sawtooth-shaped p sup + field strips. The sawtooth structure results in small electric fields directed parallel to the sensor surface and perpendicular to the drift direction which produce gutters. The drifting electrons are confined in these gutters of one saw tooth period wide. For a detector with a sawtooth period of 500 mu m, we have measured the maximum number of fully confined electrons as a function of the potential gutter depth induced by different sawtooth angles.

  11. Electroanalysis with carbon paste electrodes

    CERN Document Server

    Svancara, Ivan; Walcarius, Alain; Vytras, Karel

    2011-01-01

    Introduction to Electrochemistry and Electroanalysis with Carbon Paste-Based ElectrodesHistorical Survey and GlossaryField in Publication Activities and LiteratureCarbon Pastes and Carbon Paste ElectrodesCarbon Paste as the Binary MixtureClassification of Carbon Pastes and Carbon Paste ElectrodesConstruction of Carbon Paste HoldersCarbon Paste as the Electrode MaterialPhysicochemical Properties of Carbon PastesElectrochemical Characteristics of Carbon PastesTesting of Unmodified CPEsIntera

  12. Ion-selective electrode reviews

    CERN Document Server

    Thomas, J D R

    1985-01-01

    Ion-Selective Electrode Reviews, Volume 7 is a collection of papers that covers the applications of electrochemical sensors, along with the versatility of ion-selective electrodes. The coverage of the text includes solid contact in membrane ion-selective electrodes; immobilized enzyme probes for determining inhibitors; potentiometric titrations based on ion-pair formation; and application of ion-selective electrodes in soil science, kinetics, and kinetic analysis. The text will be of great use to chemists and chemical engineers.

  13. How to Enhance Gas Removal from Porous Electrodes?

    Science.gov (United States)

    Kadyk, Thomas; Bruce, David; Eikerling, Michael

    2016-12-01

    This article presents a structure-based modeling approach to optimize gas evolution at an electrolyte-flooded porous electrode. By providing hydrophobic islands as preferential nucleation sites on the surface of the electrode, it is possible to nucleate and grow bubbles outside of the pore space, facilitating their release into the electrolyte. Bubbles that grow at preferential nucleation sites act as a sink for dissolved gas produced in electrode reactions, effectively suctioning it from the electrolyte-filled pores. According to the model, high oversaturation is necessary to nucleate bubbles inside of the pores. The high oversaturation allows establishing large concentration gradients in the pores that drive a diffusion flux towards the preferential nucleation sites. This diffusion flux keeps the pores bubble-free, avoiding deactivation of the electrochemically active surface area of the electrode as well as mechanical stress that would otherwise lead to catalyst degradation. The transport regime of the dissolved gas, viz. diffusion control vs. transfer control at the liquid-gas interface, determines the bubble growth law.

  14. Electroformed Electrodes for Electrical-Discharge Machining

    Science.gov (United States)

    Werner, A.; Cassidenti, M.

    1984-01-01

    Copper electrodes replace graphite electrodes in many instances of electrical-discharge machining (EDM) of complex shapes. Copper electrodes wear longer and cause less contamination of EDM dielectric fluid than do graphite electrodes.

  15. Electrode models in electrical impedance tomography

    Institute of Scientific and Technical Information of China (English)

    WANG M.

    2005-01-01

    This paper presents different views on electrode modelling, which include electrode electrochemistry models for modelling the effects of electrode-electrolyte interface, electric field electrode models for modelling electrode geometry, and electrode models for modelling the effects of electrode common mode voltage and double layer capacitance. Taking the full electrode models into consideration .in electrical impedance tomography (EIT) will greatly help the optimised approach to a good solution and further understanding of the measurement principle.

  16. Oxygen reduction on teflon-bonded carbon electrode

    Institute of Scientific and Technical Information of China (English)

    周德璧; 黄可龙; 张世民

    2004-01-01

    Oxygen reduction on Teflon-bonded carbon gas diffusion electrode without catalyst in 6 mol/L KOH solution was investigated with acimpedance spectroscopy and other electrochemical techniques. The kinetic parameters were measured with an exchange current density of J0= 3.44 × 10-9 and a Tafel slope of 46 mV/dec in low overpotential range (-0.05 --0.14 V vs SCE), which are comparable with those reported on carbon supported platinum electrode. The reaction mechanism of OR and the active effect of carbon black were examined.

  17. A METHOD AND AN ELECTRODE PRODUCED BY INFILTRATION

    DEFF Research Database (Denmark)

    2014-01-01

    firing. The high temperature firing allows the Pr ions to diffuse into the CGO backbone. The resulting backbone would then have a co-doped subsurface exhibiting electronic conductivity having improved performance when used as electrode in, e.g. a fuel cell. Remaining particles of praseodymium oxide......The present invention relates to electrodes having Gd and Pr -doped cerium oxide (CGPO)backbones infiltrated with Sr -doped LaCoO3 (LSC) and a method to manufacture them. Pr ions have been introduced into a prefabricated CGO backbone by infiltrating Pr nitrate solution followed by high temperature...

  18. Ion-selective electrode reviews

    CERN Document Server

    Thomas, J D R

    1983-01-01

    Ion-Selective Electrode Reviews, Volume 5 is a collection of articles that covers ion-speciation. The book aims to present the advancements of the range and capabilities of selective ion-sensors. The topics covered in the selection are neutral carrier based ion-selective electrodes; reference electrodes and liquid junction effects in ion-selective electrode potentiometry; ion transfer across water/organic phase boundaries and analytical; and carbon substrate ion-selective electrodes. The text will be of great use to chemists and chemical engineers.

  19. Amyotrophic Lateral Sclerosis (ALS)

    Science.gov (United States)

    ... ALS Neurons' broken machinery piles up in ALS Esclerosis Lateral Amiotrófica Dormant viral genes may awaken to ... Dementia Information Page Multifocal Motor Neuropathy Information Page Multiple Sclerosis Information Page Muscular Dystrophy Information Page Myasthenia ...

  20. Amyotrophic lateral sclerosis (ALS)

    Science.gov (United States)

    Lou Gehrig disease; ALS; Upper and lower motor neuron disease; Motor neuron disease ... 98. Shaw PJ. Amyotrophic lateral sclerosis and other motor neuron diseases. In: Goldman L, Schafer AI, eds. Goldman's Cecil ...

  1. Hereditary Diffuse Gastric Cancer

    Science.gov (United States)

    ... Hereditary Diffuse Gastric Cancer Request Permissions Hereditary Diffuse Gastric Cancer Approved by the Cancer.Net Editorial Board , 11/2015 What is hereditary diffuse gastric cancer? Hereditary diffuse gastric cancer (HDGC) is an inherited ...

  2. Magnetohydrodynamic generator electrode

    Science.gov (United States)

    Marchant, David D.; Killpatrick, Don H.; Herman, Harold; Kuczen, Kenneth D.

    1979-01-01

    An improved electrode for use as a current collector in the channel of a magnetohydrodynamid (MHD) generator utilizes an elongated monolithic cap of dense refractory material compliantly mounted to the MHD channel frame for collecting the current. The cap has a central longitudinal channel which contains a first layer of porous refractory ceramic as a high-temperature current leadout from the cap and a second layer of resilient wire mesh in contact with the first layer as a low-temperature current leadout between the first layer and the frame. Also described is a monolithic ceramic insulator compliantly mounted to the frame parallel to the electrode by a plurality of flexible metal strips.

  3. Electrocatalysts for oxygen electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Yeager, E.B. (Case Western Reserve Univ., Cleveland, OH (United States))

    1991-10-01

    The objectives of the research were: to develop further understanding of the factors controlling O{sub 2} reduction and generation on various electrocatalysts, including transition metal macrocycles and oxides: to use this understanding to identify and develop much higher activity catalysts, both monofunction and bifunction; and to establish how catalytic activity for a given O{sub 2} electrocatalyst depends on catalyst-support interactions and to identify stable catalyst supports for bifunctional electrodes.

  4. Composite electrodes for lithium batteries.

    Energy Technology Data Exchange (ETDEWEB)

    Hackney, S. A.; Johnson, C. S.; Kahaian, A. J.; Kepler, K. D.; Shao-Horn, Y.; Thackeray, M. M.; Vaughey, J. T.

    1999-02-03

    The stability of composite positive and negative electrodes for rechargeable lithium batteries is discussed. Positive electrodes with spinel-type structures that are derived from orthorhombic-LiMnO{sub 2} and layered-MnO{sub 2} are significantly more stable than standard spinel Li[Mn{sub 2}]O{sub 4} electrodes when cycled electrochemically over both the 4-V and 3-V plateaus in lithium cells. Transmission electron microscope data of cycled electrodes have indicated that a composite domain structure accounts for this greater electrochemical stability. The performance of composite Cu{sub x}Sn materials as alternative negative electrodes to amorphous SnO{sub x} electrodes for lithium-ion batteries is discussed in terms of the importance of the concentration of the electrochemically inactive copper component in the electrode.

  5. Fabrication of carbon nanotubes paste electrode for determination of Cd (II) and Pb (II) ions

    Science.gov (United States)

    Le Hai, Tran; Hai, Tran Duy

    2017-09-01

    In this study, the electrode for determination of Cd (II) and Pb (II) was prepared by a paste composition of multi-wall carbon nanotubes (MWCNTs) and paraffin oil as a binder. Effect of MWCNTs/paraffin oil ratio on electrochemical behaviors of the electrodes was investigated. For the characterization of the fabricated MWCNT paste electrodes, the cyclic voltammetry, SEM images, RAMAN and XRD spectroscopy were employed. It was found that the electrode containing 20% (w/w) paraffin oil and 80 % (w/w) MWCNTs exhibited the satisfactory properties through the anodic stripping voltammetry (ASV) results. This electrode showed a reversible redox process with an electrochemical mechanism of controlled diffusion. Furthermore, the ASV results of the prepared electrode revealed a linear response of Pb (II) and Cd (II) concentrations with a detection limit of 6.33 µmol.L-1 and 0.42 µmol.L-1, respectively

  6. Electro-fenton degradation of simulation wastewater of triclosan by use of graphene doped gas-diffusion electrode%掺杂石墨烯气体扩散电极电芬顿氧化降解三氯生废水模拟

    Institute of Scientific and Technical Information of China (English)

    宋燕; 陈捷; 张国权; 杨凤林

    2014-01-01

    为了解决水中个人护理品难以处理的问题,以具有优良氧还原催化活性的掺杂石墨烯气体扩散电极( rGO/C-PTFE GDE)为阴极,构建了均相电芬顿氧化体系,探讨了石墨烯掺杂量、电流密度、电解质浓度等因素对rGO/C-PT-FE GDE原位生成H2 O2的产率和电流效率的影响,确定了电生成H2 O2的最优化条件,即石墨烯与片状石墨的质量比为1∶8,电流强度为2.0 mA/cm2,电解液浓度为0.05mol/L。该条件下经180 min电解H2 O2积累浓度可达到187.1 mg/L。以rGO/C-PTFE GDE为阴极构建了均相电芬顿氧化体系,并应用于含三氯生模拟废水的氧化降解,研究了电解液pH值和外加Fe2+浓度对三氯生去除效果的影响。结果表明:对于初始浓度为45 mg/L的三氯生,在pH值为3.0,外加Fe2+浓度0.75 mmol/L的条件下,经过180 min均相电芬顿氧化的处理,73.9%的三氯生可被氧化降解。%In order to resolve the problem of personal care product being difficult to be dealt with ,the paper constructed an undivided electro-Fenton system with the reduced graphene oxide ( rGO)-doped gas diffusion electrode (rGO/C-PTFE GDE) as cathode to achieve the electrocatalytic oxidation degradation of personal care products ( PPCPs)-triclosan .The influence of additive amount of graphene , current densities and e-lectrolyte concentration on electrochemical generation of H 2 O2 and current efficiency were investigated in detail .The most optimum conditions of producing H 2 O2 are that the mass ratio of graphene and graphite e-quals 1:8, current density is 2.0 mA/cm2 , electrolyte concentration is 0.05 mol/L.The accumulation con-centration of H2 O2 electrode after 180 minutes reaches 187.1 mg/L under which conditions .The homogene-ous electro-Fenton oxidation system was constructed to degrade triclosan simulation wastewater .The influ-ences of electrolyte pH and Fe 2+concentration on the removal rate of

  7. Diffusion coefficient in photon diffusion theory

    NARCIS (Netherlands)

    Graaff, R; Ten Bosch, JJ

    2000-01-01

    The choice of the diffusion coefficient to be used in photon diffusion theory has been a subject of discussion in recent publications on tissue optics. We compared several diffusion coefficients with the apparent diffusion coefficient from the more fundamental transport theory, D-app. Application to

  8. Diffusion coefficient in photon diffusion theory

    NARCIS (Netherlands)

    Graaff, R; Ten Bosch, JJ

    2000-01-01

    The choice of the diffusion coefficient to be used in photon diffusion theory has been a subject of discussion in recent publications on tissue optics. We compared several diffusion coefficients with the apparent diffusion coefficient from the more fundamental transport theory, D-app. Application to

  9. Microfluidic electrochemical device and process for chemical imaging and electrochemical analysis at the electrode-liquid interface in-situ

    Science.gov (United States)

    Yu, Xiao-Ying; Liu, Bingwen; Yang, Li; Zhu, Zihua; Marshall, Matthew J.

    2016-03-01

    A microfluidic electrochemical device and process are detailed that provide chemical imaging and electrochemical analysis under vacuum at the surface of the electrode-sample or electrode-liquid interface in-situ. The electrochemical device allows investigation of various surface layers including diffuse layers at selected depths populated with, e.g., adsorbed molecules in which chemical transformation in electrolyte solutions occurs.

  10. Diffusion from gel in brain: modelisation and identification.

    Science.gov (United States)

    Bellagoun, A; Meulemans, A; Cherruault, Y

    1992-03-01

    A mathematical model is proposed for describing the mechanism of diffusion from gel (Tissucol) into the extracellular space. After diffusion of the antibiotic in one dimension, the gradient concentration was determined with microvoltametric electrodes. These microelectrodes measure the free diffusible form of electroactive antibiotics in the extracellular brain space. The aim of this study was to find simultaneously the coefficient of diffusion and extraction of some antibiotics (in our case the Fotemustin) using the Alienor Algorithm. These coefficients are useful for predicting the concentration gradient into abscesses, fibrin, etc.

  11. The effects of electrode surface morphology on the actuation performance of IPMC

    Science.gov (United States)

    Palmre, Viljar; Pugal, David; Leang, Kam K.; Kim, Kwang

    2013-04-01

    It is generally understood that increasing the specific surface area of the electrodes of IPMC leads to improved electromechanical performance of the material. Most physics based models compensate the effect of high surface area of the electrodes by increasing both diffusion constant and dielectric permittivity values, while using flat electrode approximation in calculations. Herein, a model was developed to take into account the shape and area of the electrodes. High surface area of the electrodes in the model was achieved by designing 2D polymer-electrode interface as a Koch fractal structure - different generation depths and both unidirectional and random directional generations were studied. The calculations indicate that increasing the generation depth of fractals, thus surface area of the electrodes results in more overall transported charge during the actuation process. Based on the model, the effect of the specific surface area of the electrodes on the electromechanical performance was experimentally investigated. IPMCs with different Pd-Pt electrode structures were prepared and their electromechanical and electrochemical properties were examined and discussed. The methods to manipulate the surface structure of Pd-Pt electrodes were proposed.

  12. Gas sensor with multiple internal reference electrodes and sensing electrodes

    DEFF Research Database (Denmark)

    2016-01-01

    The invention relates to a potentiometric gas sensor, or potentiometric gas detection element, with multiple internal reference electrodes and multiple sensing electrodes for determining the concentrations of gas components in a gaseous mixture. The sensor for gas detection comprises: a solid...... electrolyte, at least two sensing electrodes (SEs) in solid contact with the electrolyte, and at least two internal reference electrodes (IREs) in solid contact with the electrolyte, wherein each IRE comprises a composite material, comprising a binary mixture of a metal and a metal oxide dispersed to form...

  13. Nanoscale phase change memory with graphene ribbon electrodes

    Science.gov (United States)

    Behnam, Ashkan; Xiong, Feng; Cappelli, Andrea; Wang, Ning C.; Carrion, Enrique A.; Hong, Sungduk; Dai, Yuan; Lyons, Austin S.; Chow, Edmond K.; Piccinini, Enrico; Jacoboni, Carlo; Pop, Eric

    2015-09-01

    Phase change memory (PCM) devices are known to reduce in power consumption as the bit volume and contact area of their electrodes are scaled down. Here, we demonstrate two types of low-power PCM devices with lateral graphene ribbon electrodes: one in which the graphene is patterned into narrow nanoribbons and the other where the phase change material is patterned into nanoribbons. The sharp graphene "edge" contacts enable switching with threshold voltages as low as ˜3 V, low programming currents (100. Large-scale fabrication with graphene grown by chemical vapor deposition also enables the study of heterogeneous integration and that of variability for such nanomaterials and devices.

  14. Laterally loaded masonry

    DEFF Research Database (Denmark)

    Raun Gottfredsen, F.

    In this thesis results from experiments on mortar joints and masonry as well as methods of calculation of strength and deformation of laterally loaded masonry are presented. The strength and deformation capacity of mortar joints have been determined from experiments involving a constant compressive...... stress and increasing shear. The results show a transition to pure friction as the cohesion is gradually destroyed. An interface model of a mortar joint that can take into account this aspect has been developed. Laterally loaded masonry panels have also been tested and it is found to be characteristic...

  15. Lateral Thinking of Prospective Teachers

    Science.gov (United States)

    Lawrence, A. S. Arul; Xavier, S. Amaladoss

    2013-01-01

    Edward de Bono who invented the term "lateral thinking" in 1967 is the pioneer of lateral thinking. Lateral thinking is concerned with the generation of new ideas. Liberation from old ideas and the stimulation of new ones are twin aspects of lateral thinking. Lateral thinking is a creative skills from which all people can benefit…

  16. Activation and discharge kinetics of metal hydride electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Johnsen, Stein Egil

    2003-07-01

    Potential step chronoamperometry and Electrochemical Impedance Spectroscopy (eis) measurements were performed on single metal hydride particles. For the {alpha}-phase, the bulk diffusion coefficient and the absorption/adsorption rate parameters were determined. Materials produced by atomisation, melt spinning and conventional casting were investigated. The melt spun and conventional cast materials were identical and the atomised material similar in composition. The particles from the cast and the melt spun material were shaped like parallelepipeds. A corresponding equation, for this geometry, for diffusion coupled to an absorption/adsorption reaction was developed. It was found that materials produced by melt spinning exhibited lower bulk diffusion (1.7E-14 m2/s) and absorption/adsorption reaction rate (1.0E-8 m/s), compared to materials produced by conventionally casting (1.1E-13 m2/s and 5.5E-8 m/s respectively). In addition, the influence of particle active surface and relative diffusion length were discussed. It was concluded that there are uncertainties connected to these properties, which may explain the large distribution in the kinetic parameters measured on metal hydride particles. Activation of metal hydride forming materials has been studied and an activation procedure, for porous electrodes, was investigated. Cathodic polarisation of the electrode during a hot alkaline surface treatment gave the maximum discharge capacity on the first discharge of the electrode. The studied materials were produced by gas atomisation and the spherical shape was retained during the activation. Both an AB{sub 5} and an AB{sub 2} alloy was successfully activated and discharge rate properties determined. The AB{sub 2} material showed a higher maximum discharge capacity, but poor rate properties, compared to the AB{sub 5} material. Reduction of surface oxides, and at the same time protection against corrosion of active metallic nickel, can explain the satisfying results of

  17. Gold electrodes from recordable CDs

    Science.gov (United States)

    Angnes; Richter; Augelli; Kume

    2000-11-01

    Gold electrodes are widely used in electrochemistry and electroanalytical chemistry. The notable performance when used in stripping analysis of many ionic species and the extraordinary affinity of thio compounds for its surface make these electrodes very suitable for many applications. This paper reports a simple and novel way to construct gold electrodes (CDtrodes) using recordable CDs as the gold source. The nanometer thickness of the gold layer of recordable disks (50-100 nm) favors the construction of band nanoelectrodes with areas as small as 10(-6) cm2. The plane surface can be easily used for the construction of conventional-sized gold electrodes for batch or flow injection analysis or even to obtain electrodes as large as 100 cm2. The low price of commercial recordable CDs allows a "one way use". The evaluation and applicability of these electrodes in the form of nanoelectrodes, in batch and associated with flow cells, are illustrated in this paper.

  18. Transparent Electrodes for Efficient Optoelectronics

    KAUST Repository

    Morales-Masis, Monica

    2017-03-30

    With the development of new generations of optoelectronic devices that combine high performance and novel functionalities (e.g., flexibility/bendability, adaptability, semi or full transparency), several classes of transparent electrodes have been developed in recent years. These range from optimized transparent conductive oxides (TCOs), which are historically the most commonly used transparent electrodes, to new electrodes made from nano- and 2D materials (e.g., metal nanowire networks and graphene), and to hybrid electrodes that integrate TCOs or dielectrics with nanowires, metal grids, or ultrathin metal films. Here, the most relevant transparent electrodes developed to date are introduced, their fundamental properties are described, and their materials are classified according to specific application requirements in high efficiency solar cells and flexible organic light-emitting diodes (OLEDs). This information serves as a guideline for selecting and developing appropriate transparent electrodes according to intended application requirements and functionality.

  19. Monte Carlo analysis of a lateral IBIC experiment on a 4H-SiC Schottky diode

    CERN Document Server

    Olivero, P; Gamarra, P; Jaksic, M; Giudice, A Lo; Manfredotti, C; Pastuovic, Z; Skukan, N; Vittone, E

    2016-01-01

    The transport properties of a 4H-SiC Schottky diode have been investigated by the Ion Beam Induced Charge (IBIC) technique in lateral geometry through the analysis of the charge collection efficiency (CCE) profile at a fixed applied reverse bias voltage. The cross section of the sample orthogonal to the electrodes was irradiated by a rarefied 4 MeV proton microbeam and the charge pulses have been recorded as function of incident proton position with a spatial resolution of 2 um. The CCE profile shows a broad plateau with CCE values close to 100% occurring at the depletion layer, whereas in the neutral region, the exponentially decreasing profile indicates the dominant role played by the diffusion transport mechanism. Mapping of charge pulses was accomplished by a novel computational approach, which consists in mapping the Gunn's weighting potential by solving the electrostatic problem by finite element method and hence evaluating the induced charge at the sensing electrode by a Monte Carlo method. The combina...

  20. Modelling of cycling of lithium battery with microporous carbon electrode

    Directory of Open Access Journals (Sweden)

    D. Portnyagin

    2008-12-01

    Full Text Available Charge/discharge cycles of lithium cell with microporous carbon electrode under potentiodynamic control have been modelled. Predictions of the models with variable and constant diffusion coefficient neglecting the electric field inside the particle (CPM, DFM are compared to the predictions of the models with variable and constant diffusion coefficient in which electrostatic interaction inside the particles of carbon electrode (CPME, DFME is taken into account. There is observed a considerable difference between both. Electrostatic interactions of lithium ions with each other and the charge distributed inside the particle promote intercalation during the discharge of the cell and deintercalation during the charge. The dependance of the effect of hysteresis during the cycling of the cell on the rate of change of the applied voltage is studied. The larger is the speed of change of the applied voltage the more effective is hysteresis. We have also obtained concentration profiles at different stages of charge/discharge process.

  1. Electrodynamic Arrays Having Nanomaterial Electrodes

    Science.gov (United States)

    Trigwell, Steven (Inventor); Biris, Alexandru S. (Inventor); Calle, Carlos I. (Inventor)

    2013-01-01

    An electrodynamic array of conductive nanomaterial electrodes and a method of making such an electrodynamic array. In one embodiment, a liquid solution containing nanomaterials is deposited as an array of conductive electrodes on a substrate, including rigid or flexible substrates such as fabrics, and opaque or transparent substrates. The nanomaterial electrodes may also be grown in situ. The nanomaterials may include carbon nanomaterials, other organic or inorganic nanomaterials or mixtures.

  2. Jointed Holder For Welding Electrodes

    Science.gov (United States)

    Gilbert, Jeffrey L.

    1991-01-01

    Adjustable-angle holder enables use of standard straight electrode with custom-fabricated bent gas cup for welding in difficult-to-reach places. Electrode replaced easily, without removing cup, with aid of tool loosening miniature collet nut on holder. Consumes fewer electrodes for given amount of welding. Angle of holder continuously adjustable to fit angle of gas cup or geometry of part welded. Holder made double-jointed to accommodate gas cup having compound angles.

  3. Onset dominance in lateralization.

    Science.gov (United States)

    Freyman, R L; Zurek, P M; Balakrishnan, U; Chiang, Y C

    1997-03-01

    Saberi and Perrott [Acustica 81, 272-275 (1995)] found that the in-head lateralization of a relatively long-duration pulse train could be controlled by the interaural delay of the single pulse pair that occurs at onset. The present study examined this further, using an acoustic pointer measure of lateralization, with stimulus manipulations designed to determine conditions under which lateralization was consistent with the interaural onset delay. The present stimuli were wideband pulse trains, noise-burst trains, and inharmonic complexes, 250 ms in duration, chosen for the ease with which interaural delays and correlations of select temporal segments of the stimulus could be manipulated. The stimulus factors studied were the periodicity of the ongoing part of the signal as well as the multiplicity and ambiguity of interaural delays. The results, in general, showed that the interaural onset delay controlled lateralization when the steady state binaural cues were relatively weak, either because the spectral components were only sparsely distributed across frequency or because the interaural time delays were ambiguous. Onset dominance can be disrupted by sudden stimulus changes within the train, and several examples of such changes are described. Individual subjects showed strong left-right asymmetries in onset effectiveness. The results have implications for understanding how onset and ongoing interaural delay cues contribute to the location estimates formed by the binaural auditory system.

  4. Laterality and reproductive indices.

    Science.gov (United States)

    Kalichman, Leonid; Kobyliansky, Eugene

    2008-01-01

    Several previous studies support the association between manual dominance and age at menarche or age at menopause. The aim of the present study was to estimate the association between indices of laterality and reproductive indices. The studied sample comprised 650 Chuvashian women aged 18 to 80 years (mean, 46.9; SD = 16.2). The independent-sample t test was used to compare the age at menarche or age at menopause between individuals with right or left dominance of handedness, dominant eye, hand clasping, and arm folding. No significant differences in age at menarche or age at menopause between women with right and left dominance in any of the studied laterality indices were found. This is the first study that simultaneously evaluates the association between dominance in four laterality indices (handedness, dominant eye, hand clasping, and arm folding) and two reproductive indices (age at menarche and age at menopause). Result of our study do not support the hypothesis of a possible association between handedness (and other indices of laterality) and an early age at menarche or age at natural menopause.

  5. Scalable Coating and Properties of Transparent, Flexible, Silver Nanowire Electrodes

    KAUST Repository

    Hu, Liangbing

    2010-05-25

    We report a comprehensive study of transparent and conductive silver nanowire (Ag NW) electrodes, including a scalable fabrication process, morphologies, and optical, mechanical adhesion, and flexibility properties, and various routes to improve the performance. We utilized a synthesis specifically designed for long and thin wires for improved performance in terms of sheet resistance and optical transmittance. Twenty Ω/sq and ∼ 80% specular transmittance, and 8 ohms/sq and 80% diffusive transmittance in the visible range are achieved, which fall in the same range as the best indium tin oxide (ITO) samples on plastic substrates for flexible electronics and solar cells. The Ag NW electrodes show optical transparencies superior to ITO for near-infrared wavelengths (2-fold higher transmission). Owing to light scattering effects, the Ag NW network has the largest difference between diffusive transmittance and specular transmittance when compared with ITO and carbon nanotube electrodes, a property which could greatly enhance solar cell performance. A mechanical study shows that Ag NW electrodes on flexible substrates show excellent robustness when subjected to bending. We also study the electrical conductance of Ag nanowires and their junctions and report a facile electrochemical method for a Au coating to reduce the wire-to-wire junction resistance for better overall film conductance. Simple mechanical pressing was also found to increase the NW film conductance due to the reduction of junction resistance. The overall properties of transparent Ag NW electrodes meet the requirements of transparent electrodes for many applications and could be an immediate ITO replacement for flexible electronics and solar cells. © 2010 American Chemical Society.

  6. Ultrathin metallic interlayers in vacuum deposited MoOx/metal/MoOx electrodes for organic solar cells

    Science.gov (United States)

    Travkin, V. V.; Luk'yanov, A. Yu.; Drozdov, M. N.; Vopilkin, E. A.; Yunin, P. A.; Pakhomov, G. L.

    2016-12-01

    Eight types of practically important metals were tested as interlayers in MoOx/Metal/MoOx composite electrodes. Ultrathin semitransparent electrodes with a fixed thickness were deposited on glass, using thermal vacuum evaporation, and characterized by various microscopic and X-ray techniques and by mass spectrometry profiling. The optical transmission and sheet resistance of the electrodes were compared as key parameters for photovoltaic applications. We attempted to find correlations between the chemical properties of embedded metals and the structural/conducting properties of composite electrodes. In general, the electrodes with noble metal interlayers feature a better conductivity, whereas their average transparency in the visible and near infrared range is similar to that of electrodes with reactive metals. Diffusion and oxidation processes in composite electrodes were examined by the SIMS depth profiling technique.

  7. Learning, diffusion and the industry life cycle

    OpenAIRE

    Zhu Wang

    2006-01-01

    An industry typically experiences initial mass entry and later shakeout of producers over its life cycle. It can be explained as a competitive equilibrium outcome driven by the dynamic interaction between technology progress and demand diffusion. When a new product is introduced, high-income consumers tend to adopt it first. Technology then improves with cumulative output and demand growth generates S-shaped diffusion as the product penetrates lower-income groups. Eventually fewer new adopter...

  8. Ion-selective electrode reviews

    CERN Document Server

    Thomas, J D R

    1982-01-01

    Ion-Selective Electrode Reviews, Volume 3, provides a review of articles on ion-selective electrodes (ISEs). The volume begins with an article on methods based on titration procedures for surfactant analysis, which have been developed for discrete batch operation and for continuous AutoAnalyser use. Separate chapters deal with detection limits of ion-selective electrodes; the possibility of using inorganic ion-exchange materials as ion-sensors; and the effect of solvent on potentials of cells with ion-selective electrodes. Also included is a chapter on advances in calibration procedures, the d

  9. Electrodes for Semiconductor Gas Sensors.

    Science.gov (United States)

    Lee, Sung Pil

    2017-03-25

    The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and surface states of electrode-semiconductor interfaces on their characteristics is studied. This study describes that the gas interaction mechanism of the electrode-semiconductor interfaces should take into account the interfacial zone, surface states, image force, and tunneling effect.

  10. 扩散张量成像评价肌萎缩侧索硬化上运动神经元损害的最适感兴趣区%Optimal Regions of Interest of MR Diffusion Tensor Imaging: Quantitative Measurements on Upper Motor Neuron of Patients with Amyotrophic Lateral Sclerosis

    Institute of Scientific and Technical Information of China (English)

    刘涛; 陈峰; 文国强; 欧阳锋; 黄仕雄; 李建军

    2012-01-01

    Objective:To explore the optimal regions of interest of MR diffusion tensor imaging (DTI) in amyotrophic lateral sclerosis (ALS). Methods: Sixteen patients (M : F=9 : 7, [52.1±10. 0] years old) with El Escorial definite, probable, or probable- laboratory support ALS were studied. These patients were compared with 15 healthy, age and sex-matched controls (M : F=8 : 7, [50.3 ± 10. 8] years old). The two groups were all underwent a conventional MRI and DTI sequence. DTI was performed using a single shot SE-EPI with 25 noncollinear diffusion gradient di-rections (b=l000 s/mm2) on a 1. 5-T MR system. For quantitative assessment of the FA and ADC, values of bilateral corticospinal tract regions were measured on all 8 regions, and statistical analysis was performed using two sample independent t-test. Correlation between diffusion parameters and various clinical variables were investigated by Pearson or Spearman correlation analysis. Results: Focal slight low signal intensity on 11 WI and high signal intensity (hyperin-tense to gray matter) on T2WI was demonstrated in 8 ALS cases (53. 3%) in bilateral posterior limb of internal capsule (PIC). More extensive corticospinal tract abnormality, including the periventricular white matter, the PIC, and the cerebral peduncle, was detected in 4 ALS cases (26. 7%). In control group, the focal slight low signal intensity on T1 WI and slight high signal intensity (isointense to gray matter) on T2 WI was demonstrated in all 16 subjects in bilateral PIC. A significant reduction in fractional anisotropy(FA) (t = 3. 452, P = 0. 002) and increase in the average diffusion coefficient(ADC) was found (t= — 2. 670, P = 0. 012) on the level of posterior limb of internal capsule in ALS group. Although there was a trend towards reduced FA and elevated ADC on the level of the subcortical white matter (SWM) of precentral gyrul in ALS group, this did not reach to statistical significance. The FA correlated with measures of disease severity

  11. Influence of implantation on the electrochemical properties of smooth and porous TiN coatings for stimulation electrodes

    Science.gov (United States)

    Meijs, S.; Sørensen, C.; Sørensen, S.; Rechendorff, K.; Fjorback, M.; Rijkhoff, N. J. M.

    2016-04-01

    Objective. To determine whether changes in electrochemical properties of porous titanium nitride (TiN) electrodes as a function of time after implantation are different from those of smooth TiN electrodes. Approach. Eight smooth and 8 porous TiN coated electrodes were implanted in 8 rats. Before implantation, voltage transients, cyclic voltammograms and impedance spectra were recorded in phosphate buffered saline (PBS). After implantation, these measurements were done weekly to investigate how smooth and porous electrodes were affected by implantation. Main results. The electrode capacitance of the porous TiN electrodes decreased more than the capacitance of the smooth electrodes due to acute implantation under fast measurement conditions (such as stimulation pulses). This indicates that protein adhesion presents a greater diffusion limitation for counter-ions for the porous than for the smooth electrodes. The changes in electrochemical properties during the implanted period were similar for smooth and porous TiN electrodes, indicating that cell adhesion poses a similar diffusion limitation for smooth and porous electrodes. Significance. This knowledge can be used to optimize the porous structure of the TiN film, so that the effect of protein adhesion on the electrochemical properties is diminished. Alternatively, an additional coating could be applied on the porous TiN that would prevent or minimize protein adhesion.

  12. Diffusion archeology for diffusion progression history reconstruction.

    Science.gov (United States)

    Sefer, Emre; Kingsford, Carl

    2016-11-01

    Diffusion through graphs can be used to model many real-world processes, such as the spread of diseases, social network memes, computer viruses, or water contaminants. Often, a real-world diffusion cannot be directly observed while it is occurring - perhaps it is not noticed until some time has passed, continuous monitoring is too costly, or privacy concerns limit data access. This leads to the need to reconstruct how the present state of the diffusion came to be from partial diffusion data. Here, we tackle the problem of reconstructing a diffusion history from one or more snapshots of the diffusion state. This ability can be invaluable to learn when certain computer nodes are infected or which people are the initial disease spreaders to control future diffusions. We formulate this problem over discrete-time SEIRS-type diffusion models in terms of maximum likelihood. We design methods that are based on submodularity and a novel prize-collecting dominating-set vertex cover (PCDSVC) relaxation that can identify likely diffusion steps with some provable performance guarantees. Our methods are the first to be able to reconstruct complete diffusion histories accurately in real and simulated situations. As a special case, they can also identify the initial spreaders better than the existing methods for that problem. Our results for both meme and contaminant diffusion show that the partial diffusion data problem can be overcome with proper modeling and methods, and that hidden temporal characteristics of diffusion can be predicted from limited data.

  13. Point Electrode Studies of the Solid Electrolyte-Electrode Interface

    DEFF Research Database (Denmark)

    Jacobsen, Torben

    \\parbox[t]{7.3cm}{Strong anodic activation due to computer communication error.} It is seen that as long as the electrode is kept at the equilibrium potential, the capacity pr.\\,unit area is constant, indicating a stable reaction zone. Polarising the electrode a decrease in this ratio is observed. Although......In the development of new electrode materials for high temperature Solid Oxide Fuel Cells methods are needed for the electrochemical evaluation of the catalytic properties of the materials. A major problem in the comparison of materials is how to determine the geometry and the effective length...... of the active reaction zone, the triple phase boundary. One way of solving this is by the application of point electrodes where the electrode-electrolyte contact is assumed to be circular with a radius calculated from the high frequency impedance. The perimeter is the taken as the length of the reaction zone...

  14. Fabrication Method for Laboratory-Scale High-Performance Membrane Electrode Assemblies for Fuel Cells.

    Science.gov (United States)

    Sassin, Megan B; Garsany, Yannick; Gould, Benjamin D; Swider-Lyons, Karen E

    2017-01-03

    Custom catalyst-coated membranes (CCMs) and membrane electrode assemblies (MEAs) are necessary for the evaluation of advanced electrocatalysts, gas diffusion media (GDM), ionomers, polymer electrolyte membranes (PEMs), and electrode structures designed for use in next-generation fuel cells, electrolyzers, or flow batteries. This Feature provides a reliable and reproducible fabrication protocol for laboratory scale (10 cm(2)) fuel cells based on ultrasonic spray deposition of a standard Pt/carbon electrocatalyst directly onto a perfluorosulfonic acid PEM.

  15. Light addressable gold electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Khalid, Waqas

    2011-07-01

    The main objective carried out in this dissertation was to fabricate Light Amplified Potentiometric sensors (LAPS) based upon the semiconductor nanoparticles (quantum dots) instead of its bulk form. Quantum dots (QDs) were opted for this device fabrication because of their superior fluorescent, electric and catalytic properties. Also in comparison to their bulk counterparts they will make device small, light weighted and power consumption is much lower. QDs were immobilized on a Au substrate via 1,4 benzene dithiol (BDT) molecule. Initially a self-assembled monolayer (SAM) of BDT was established on Au substrate. Because of SAM, the conductivity of Au substrate decreased dramatically. Furthermore QDs were anchored with the help of BDT molecule on Au substrate. When QDs immobilized on Au substrate (QD/Au) via BDT molecule were irradiated with UV-visible light, electron-hole pairs were generated in QDs. The surface defect states in QDs trapped the excited electrons and long lived electron-hole pairs were formed. By the application of an appropriate bias potential on Au substrate the electrons could be supplied or extracted from the QDs via tunneling through BDT. Thus a cathodic or anodic current could be observed depending upon bias potential under illumination. However without light illumination the QD/Au electrode remained an insulator. To improve the device different modifications were made, including different substrates (Au evaporated on glass, Au evaporated on mica sheets and Au sputtered on SiO{sub 2}/Si) and different dithiol molecules (capped and uncapped biphenyl 4,4' dithiol and capped and uncapped 4,4' dimercaptostilbenes) were tried. Also different QD immobilization techniques (normal incubation, spin coating, layer by layer assembly (LbL) of polyelectrolytes and heat immobilization) were employed. This device was able to detect electrochemically different analytes depending upon the QDs incorporated. For example CdS QDs were able to detect 4

  16. Lateral heat transfer in conducting and mutually irradiating plates

    Energy Technology Data Exchange (ETDEWEB)

    Krishnaprakas, C.K.; Badari Narayana, K. [Thermal Systems Group, ISRO Satellite Centre, Bangalore 560 017 (India)

    2004-05-01

    Lateral heat transfer effect in conducting and mutually irradiating parallel plates has been investigated. The effect of reflection in the diffuse-specular regime has been included. The governing equation of this problem is a complicated integro-differential equation, and this has been solved using the accurate Gauss-Jacobi orthogonal collocation method. The effective thermal conductivity along the lateral direction increases with decreasing conduction-radiation number, increasing emittance of the plates and increasing spacing. Specular reflection effects are insignificant. (orig.)

  17. Lateral Attitude Change.

    Science.gov (United States)

    Glaser, Tina; Dickel, Nina; Liersch, Benjamin; Rees, Jonas; Süssenbach, Philipp; Bohner, Gerd

    2015-08-01

    The authors propose a framework distinguishing two types of lateral attitude change (LAC): (a) generalization effects, where attitude change toward a focal object transfers to related objects, and (b) displacement effects, where only related attitudes change but the focal attitude does not change. They bring together examples of LAC from various domains of research, outline the conditions and underlying processes of each type of LAC, and develop a theoretical framework that enables researchers to study LAC more systematically in the future. Compared with established theories of attitude change, the LAC framework focuses on lateral instead of focal attitude change and encompasses both generalization and displacement. Novel predictions and designs for studying LAC are presented.

  18. Treatment of lateral epicondylitis.

    Science.gov (United States)

    Johnson, Greg W; Cadwallader, Kara; Scheffel, Scot B; Epperly, Ted D

    2007-09-15

    Lateral epicondylitis is a common overuse syndrome of the extensor tendons of the forearm. It is sometimes called tennis elbow, although it can occur with many activities. The condition affects men and women equally and is more common in persons 40 years or older. Despite the prevalence of lateral epicondylitis and the numerous treatment strategies available, relatively few high-quality clinical trials support many of these treatment options; watchful waiting is a reasonable option. Topical nonsteroidal anti-inflammatory drugs, corticosteroid injections, ultrasonography, and iontophoresis with nonsteroidal anti-inflammatory drugs appear to provide short-term benefits. Use of an inelastic, nonarticular, proximal forearm strap (tennis elbow brace) may improve function during daily activities. Progressive resistance exercises may confer modest intermediate-term results. Evidence is mixed on oral nonsteroidal antiinflammatory drugs, mobilization, and acupuncture. Patients with refractory symptoms may benefit from surgical intervention. Extracorporeal shock wave therapy, laser treatment, and electromagnetic field therapy do not appear to be effective.

  19. [Lateral lumbar disk herniation].

    Science.gov (United States)

    Deburge, A; Barre, E; Guigui, P

    A retrospective study of 41 lateral discal hernias observed between 1984 and 1991 were studied among the 1080 discal hernias treated during this period. CT scan, performed in all cases, distinguished several different types of hernia: foramen hernias (26), extraforamen hernias (12), mixed forms (5) associated with canal component (11). Thirteen disco scans were required. Nucleolysis was performed in 24 patients (58%) and surgical treatment was the first intention choice in 17 (41%). Outcome, evaluated with a function score developed in the unit were good in the 17 surgery cases (100%). In the nucleolysis patients results were good or excellent in 13, average in 4, and poor in 7. Five of the nucleolysis failures were later operated leading to good results in 3, average in 1 and no change in 1. Indications for surgery are more frequent in this type of discal hernia and results in our surgical series were better than those for chemonucleolysis.

  20. The lateral angle revisited

    DEFF Research Database (Denmark)

    Morgan, Jeannie; Lynnerup, Niels; Hoppa, R.D.

    2013-01-01

    measurements taken from computed tomography (CT) scans. Previous reports have observed that the lateral angle size in females is significantly larger than in males. The method was applied to an independent series of 77 postmortem CT scans (42 males, 35 females) to validate its accuracy and reliability...... method appears to be of minimal practical use in forensic anthropology and archeology. © 2013 American Academy of Forensic Sciences....

  1. Lateral Elbow Tendinopathy

    Science.gov (United States)

    Bhabra, Gev; Wang, Allan; Ebert, Jay R.; Edwards, Peter; Zheng, Monica; Zheng, Ming H.

    2016-01-01

    Lateral elbow tendinopathy, commonly known as tennis elbow, is a condition that can cause significant functional impairment in working-age patients. The term tendinopathy is used to describe chronic overuse tendon disorders encompassing a group of pathologies, a spectrum of disease. This review details the pathophysiology of tendinopathy and tendon healing as an introduction for a system grading the severity of tendinopathy, with each of the 4 grades displaying distinct histopathological features. Currently, there are a large number of nonoperative treatments available for lateral elbow tendinopathy, with little guidance as to when and how to use them. In fact, an appraisal of the clinical trials, systematic reviews, and meta-analyses studying these treatment modalities reveals that no single treatment reliably achieves outstanding results. This may be due in part to the majority of clinical studies to date including all patients with chronic tendinopathy rather than attempting to categorize patients according to the severity of disease. We relate the pathophysiology of the different grades of tendinopathy to the basic science principles that underpin the mechanisms of action of the nonoperative treatments available to propose a treatment algorithm guiding the management of lateral elbow tendinopathy depending on severity. We believe that this system will be useful both in clinical practice and for the future investigation of the efficacy of treatments. PMID:27833925

  2. 76 FR 67411 - Small Diameter Graphite Electrodes From the People's Republic of China: Extension of Time Limit...

    Science.gov (United States)

    2011-11-01

    ... International Trade Administration Small Diameter Graphite Electrodes From the People's Republic of China... antidumping duty order on small diameter graphite electrodes from the People's Republic of China (PRC) for the... Carbon LLC and Superior Graphite, Co. The preliminary results of the review are currently due no later...

  3. Restructuring of porous nickel electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Lenhart, S.J.; Macdonald, D.D.; Pound, B.G.

    1984-08-01

    A transmission line model for the electrochemical impedance of porous electrodes was used to study the degradation of nickel battery plates throughout their cycle life. The model was shown to successfully account for changes in the observed electrode properties in terms of simultaneous restructuring of the active mass and rupture of particleparticle ohmic contacts.

  4. Ion-selective electrodes, 3

    Energy Technology Data Exchange (ETDEWEB)

    Pungor, E. (ed.)

    1981-01-01

    Thirty-two papers which were presented at the Third Symposium on Ion-Selective Electrodes are presented in this Proceedings. These papers dealt with standardization, fabrication, chemical properties of ion-selective electrodes and their application. Selected papers have been abstracted and indexed separately for the data base. (ATT)

  5. ELECTROCHEMISTRY OF FUEL CELL ELECTRODES.

    Science.gov (United States)

    optimization of fuel cell electrodes. Hydrogen oxidation and reduction, the reduction of oxygen, and the oxidation of formic acid, a soluble organic...substance, were selected for these studiees because of their relevance to fuel cell systems and because of their relative simplicity. The electrodes

  6. Making EDM Electrodes By Stereolithography

    Science.gov (United States)

    Barlas, Philip A.

    1988-01-01

    Stereolithography is computer-aided manufacturing technique. Used to make models and molds of electrodes for electrical-discharge machining (EDM). Eliminates intermediate steps in fabrication of plastic model of object used in making EDM electrode to manufacture object or mold for object.

  7. Silicon ohmic lateral-contact MEMS switch for RF applications

    Science.gov (United States)

    Rogozhin, A.; Miakonkikh, A.; Tatarintsev, A.; Lebedev, K.; Kalnov, V.; Rudenko, K.; Lukichev, V.

    2016-12-01

    Application variety and huge potential market of RF MEMS switches guarantee relentless research interest to the field. There are lots of different types of MEMS switches. Direct contact MEMS switches are simplifier for integration than capacitive MEMS switches. Lateral technology considerably simplifies the formation process. The objective of this research is to estimate characteristics of the simple direct-contact lateral MEMS switch and to understand the improvement directions. The MEMS switches were fabricated on the SOI wafers by e-beam lithography, dry etching and wet HF-etching. E-beam lithography and dry etching were used to form the cantilever and electrodes on the buried oxide layer. The structure with two control electrodes was used. IV characteristics were measured by Keithley 4200-SCS. The distance between cantilever and control electrodes was 100 nm. From the obtained IV characteristics it is clear that the devices switches at about 60 V. High control voltage could be explained by the large distance between cantilever and control electrode, and high rigidity of the cantilever. Following simulation in COMSOL Multiphysics showed that the control voltage could be decreased to 20-30 V by adding of spring element to the cantilever and device geometry modification.

  8. Gel electrolytes and electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Fleischmann, Sven; Bunte, Christine; Mikhaylik, Yuriy V.; Viner, Veronika G.

    2017-09-05

    Gel electrolytes, especially gel electrolytes for electrochemical cells, are generally described. In some embodiments, the gel electrolyte layers comprise components a) to c). Component a) may be at least one layer of at least one polymer comprising polymerized units of: a1) at least one monomer containing an ethylenically unsaturated unit and an amido group and a2) at least one crosslinker. Component b) may be at least one conducting salt and component c) may be at least one solvent. Electrodes may comprise the components a), d) and e), wherein component a) may be at least one layer of at least one polymer as described herein. Component d) may be at least one electroactive layer and component e) may be at least one ceramic layer. Furthermore, electrochemical cells comprising component a) which may be at least one layer of at least one polymer as described herein, are also provided.

  9. Effective ultrasound electrochemical degradation of methylene blue wastewater using a nanocoated electrode.

    Science.gov (United States)

    Yang, Bo; Zuo, Jiane; Tang, Xinhua; Liu, Fenglin; Yu, Xin; Tang, Xinyao; Jiang, Hui; Gan, Lili

    2014-07-01

    A novel sonoelectrochemical catalytic oxidation-driven process using a nanocoated electrode to treat methylene blue (MB) wastewater was developed. The nano-scale (nanocoated) electrode generated more hydroxyl radicals than non-nano-scale (non-nanocoated) electrodes did. However, hydroxyl radicals were easily adsorbed by the nanomaterial and thus were not able to enter the solution. Supersonic waves were found to enhance the mass-transfer effect on the nanocoated electrode surface, resulting in rapid diffusion of the generated hydroxyl radicals into the solution. In solution, the hydroxyl radicals then reacted with organic pollutants in the presence of ultrasonic waves. The effect of the nanocoated electrode on the MB wastewater treatment process was enhanced by ultrasound when compared to the non-nanocoated electrode used under the same conditions. The synergy of the nanocoated electrode and ultrasonic waves towards MB degradation was then studied. The optimum operating conditions resulted in a 92% removal efficiency for TOC and consisted of a current of 600 mA, an ultrasound frequency of 45 kHz, and a supersonic power of 250 W. The mechanism of ultrasound enhancement of the nanocoated electrode activity with respect to MB treatment is discussed. The reaction intermediates of the sonoelectrochemical catalytic oxidation process were monitored, and degradation pathways were proposed. The sonoelectrochemical catalytic oxidation-driven process using nanocoated electrodes was found to be a very efficient method for the treatment of non-biodegradable wastewater. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Enhanced electrochemical nanoring electrode for analysis of cytosol in single cells.

    Science.gov (United States)

    Zhuang, Lihong; Zuo, Huanzhen; Wu, Zengqiang; Wang, Yu; Fang, Danjun; Jiang, Dechen

    2014-12-02

    A microelectrode array has been applied for single cell analysis with relatively high throughput; however, the cells were typically cultured on the microelectrodes under cell-size microwell traps leading to the difficulty in the functionalization of an electrode surface for higher detection sensitivity. Here, nanoring electrodes embedded under the microwell traps were fabricated to achieve the isolation of the electrode surface and the cell support, and thus, the electrode surface can be modified to obtain enhanced electrochemical sensitivity for single cell analysis. Moreover, the nanometer-sized electrode permitted a faster diffusion of analyte to the surface for additional improvement in the sensitivity, which was evidenced by the electrochemical characterization and the simulation. To demonstrate the concept of the functionalized nanoring electrode for single cell analysis, the electrode surface was deposited with prussian blue to detect intracellular hydrogen peroxide at a single cell. Hundreds of picoamperes were observed on our functionalized nanoring electrode exhibiting the enhanced electrochemical sensitivity. The success in the achievement of a functionalized nanoring electrode will benefit the development of high throughput single cell electrochemical analysis.

  11. Thermal characterization of Li-ion cell electrodes by photothermal deflection spectroscopy

    Science.gov (United States)

    Loges, André; Herberger, Sabrina; Werner, Daniel; Wetzel, Thomas

    2016-09-01

    Contactless and temperature-dependent evaluation of thermal diffusivities of Li-ion cell electrodes based on photothermal deflection spectroscopy (PDS) measurements is introduced and applied to electrodes from three prismatic hardcase Li-ion cells. The accuracy of the method is validated using reference materials, which cover a wide range of thermal diffusivity. The effective thermal diffusivities of the three anode and cathode coatings and of the current collectors are determined in the temperature range of 5-45 °C. Furthermore, the temperature-dependent specific heat capacity of the electrodes is evaluated by differential scanning calorimetry (DSC) measurements in the same temperature range. Based on the experimental results the through-plane and in-plane thermal conductivity of the electrodes is calculated and compared to previously reported values. The results indicate significant influence of the porosity and manufacturing process on the effective thermal conductivity of the electrodes. The three mayor impact factors on thermal conductivity of electrodes are (i) composition, (ii) morphology of the coating and (iii) the thickness ratio of coating to current collector.

  12. Composite electrode/electrolyte structure

    Science.gov (United States)

    Visco, Steven J.; Jacobson, Craig P.; DeJonghe, Lutgard C.

    2004-01-27

    Provided is an electrode fabricated from highly electronically conductive materials such as metals, metal alloys, or electronically conductive ceramics. The electronic conductivity of the electrode substrate is maximized. Onto this electrode in the green state, a green ionic (e.g., electrolyte) film is deposited and the assembly is co-fired at a temperature suitable to fully densify the film while the substrate retains porosity. Subsequently, a catalytic material is added to the electrode structure by infiltration of a metal salt and subsequent low temperature firing. The invention allows for an electrode with high electronic conductivity and sufficient catalytic activity to achieve high power density in ionic (electrochemical) devices such as fuel cells and electrolytic gas separation systems.

  13. Electrode for a lithium cell

    Science.gov (United States)

    Thackeray, Michael M.; Vaughey, John T.; Dees, Dennis W.

    2008-10-14

    This invention relates to a positive electrode for an electrochemical cell or battery, and to an electrochemical cell or battery; the invention relates more specifically to a positive electrode for a non-aqueous lithium cell or battery when the electrode is used therein. The positive electrode includes a composite metal oxide containing AgV.sub.3O.sub.8 as one component and one or more other components consisting of LiV.sub.3O.sub.8, Ag.sub.2V.sub.4O.sub.11, MnO.sub.2, CF.sub.x, AgF or Ag.sub.2O to increase the energy density of the cell, optionally in the presence of silver powder and/or silver foil to assist in current collection at the electrode and to improve the power capability of the cell or battery.

  14. Hippocampal Theta Dysfunction after Lateral Fluid Percussion Injury

    OpenAIRE

    2010-01-01

    Chronic memory deficits are a major cause of morbidity following traumatic brain injury (TBI). In the rat, the hippocampal theta rhythm is a well-studied correlate of memory function. This study sought to investigate disturbances in hippocampal theta rhythm following lateral fluid percussion injury in the rat. A total of 13 control rats and 12 TBI rats were used. Electrodes were implanted in bilateral hippocampi and an electroencephalogram (EEG) was recorded while the rats explored a new envi...

  15. Magnetite nanoparticles-chitosan composite containing carbon paste electrode for glucose biosensor application.

    Science.gov (United States)

    Kavitha, A L; Prabu, H Gurumallesh; Babu, S Ananda; Suja, S K

    2013-01-01

    This work was aimed to develop reusable magnetite chitosan composite containing carbon paste electrode for biosensor application. Glucose oxidase (GOx) enzyme was used to prepare GOx-magnetite-chitosan nanocomposite containing carbon paste electrode for sensitive detection of glucose. The immobilized enzyme retained its bioactivity, exhibited a surface confined reversible electron transfer reaction, and had good stability. The surface parameters like surface coverage (tau), Diffusion coefficient (D0), and rate constant (kS) were studied. The carbon paste modified electrode virtually eliminated the interference during the detection of glucose. The excellent performance of the biosensor is attributed to large surface-to-volume ratio, high conductivity and good biocompatibility of chitosan, which enhances the enzyme absorption and promotes electron transfer between redox enzymes and the surface of electrode. The shelf life of the developed electrode system is about 12 weeks under refrigerated conditions. We report for the first time in the fabrication of carbon paste bioelectrode containing magnetite-chitosan-GOx.

  16. Investigation of nanosecond-pulsed dielectric barrier discharge actuators with powered electrodes of different exposures

    Science.gov (United States)

    Xu, Shuangyan; Cai, Jinsheng; Lian, Yongsheng

    2017-09-01

    Nanosecond-pulsed dielectric barrier discharge actuators with powered electrodes of different exposures were investigated numerically by using a newly proposed plasma kinetic model. The governing equations include the coupled continuity plasma discharge equation, drift-diffusion equation, electron energy equation, Poisson’s equation, and the Navier-Stokes equations. Powered electrodes of three different exposures were simulated to understand the effect of surface exposure on plasma discharge and surrounding flow field. Our study showed that the fully exposed powered electrode resulted in earlier reduced electric field breakdown and more intensive discharge characteristics than partially exposed and rounded-exposed ones. Our study also showed that the reduced electric field and heat release concentrated near the right upper tip of the powered electrode. The fully exposed electrode also led to stronger shock wave, higher heating temperature, and larger heated area.

  17. Kinetics of CO2 reduction in KOH/methanol electrolyte on Pb electrode

    Institute of Scientific and Technical Information of China (English)

    SONG Shuang; HE Zhi-qiao; YE Jie-xu; CHEN Jian-meng

    2007-01-01

    The electrochemical reduction of CO2 on a Pb electrode was investigated in 0.1 mol/L KOH/methanol electrolyte at different temperatures and pressures. A graphite electrode was employed as the counter electrode, and an AglAgCl ( sat. KCl) electrode was used as the reference electrode. The Tafel plots of the products by the electrochemical reduction of CO2 showed that the formation process of HCOOH differed from that of CO and the reduction of CO2 was not limited by the diffusion of CO2 in the investigated potential range. Kinetic analysis indicated that the reaction orders were 0.573 for electrochemical reduction of CO2 to CO and 0. 671 for CO2 to HCOOH in the cathodic direction.

  18. Advantage of four-electrode over two-electrode defibrillators

    Science.gov (United States)

    Bragard, J.; Šimić, A.; Laroze, D.; Elorza, J.

    2015-12-01

    Defibrillation is the standard clinical treatment used to stop ventricular fibrillation. An electrical device delivers a controlled amount of electrical energy via a pair of electrodes in order to reestablish a normal heart rate. We propose a technique that is a combination of biphasic shocks applied with a four-electrode system rather than the standard two-electrode system. We use a numerical model of a one-dimensional ring of cardiac tissue in order to test and evaluate the benefit of this technique. We compare three different shock protocols, namely a monophasic and two types of biphasic shocks. The results obtained by using a four-electrode system are compared quantitatively with those obtained with the standard two-electrode system. We find that a huge reduction in defibrillation threshold is achieved with the four-electrode system. For the most efficient protocol (asymmetric biphasic), we obtain a reduction in excess of 80% in the energy required for a defibrillation success rate of 90%. The mechanisms of successful defibrillation are also analyzed. This reveals that the advantage of asymmetric biphasic shocks with four electrodes lies in the duration of the cathodal and anodal phase of the shock.

  19. Electrochemical Reduction Behaviour of Zileuton at a Dropping Mercury Electrode by Polarography

    Directory of Open Access Journals (Sweden)

    N. Y. Sreedhar

    2010-01-01

    Full Text Available Electrochemical behaviour of anticancer drug zileuton was investigated by direct current polarography (DCP and differential pulse polarography using a dropping mercury electrode (DME as working electrode and Ag/AgCl reference electrode in universal buffer of pH range from 2.0 to 12.0. The drug was extracted from the dosage forms in dimethyl formamide (DMF. Kinetic parameters such as diffusion co-efficient (D and heterogeneous forward rate constants (k0f,h are evaluated and reported. The differential pulse polarographic method has been developed for the determination of this drug in pharmaceutical formulations.

  20. Effect of Some Metal Ion Dopants on Electrochemical Properties of Ni(OH)2 Film Electrode

    Institute of Scientific and Technical Information of China (English)

    ZHANG Heng-bin; LIU Han-san; CAO Xue-jing; SUN Chia-chung

    2003-01-01

    The Ni(OH)2 film electrodes doped respectively with alkali-earth metal aluminum, lead, partial transition metal and some rare-earth metal(altogether 17 kinds of metals) ions were prepared by cathode electrodeposition. The electrode reaction reversibility, the difficult extent of oxygen evolution, the proton diffusion coefficient, the discharge potential of middle value and the active material utilization of the Ni(OH)2 film electrode were compared with those of the ones doped with the metal ions by means of cyclic voltammetry, potential step and constant current charge-discharge experiments. It was found that Ca2+, Co2+, Cd2+, Al3+ etc. have obviously positive effect.

  1. Preset Electrodes for Electrical-Discharge Machining

    Science.gov (United States)

    Coker, Bill E.

    1987-01-01

    New electrode holder for electrical-discharge machining (EDM) provides for repeatable loading and setting of many electrodes. New holder is rotating-index tool carrying six, eight, or more electrodes. Before use, all electrodes set with aid of ring surrounding tool, and locked in position with screws. When electrode replaced, EDM operator pulls spring-loaded pin on tool so it rotates about center pin. Fresh electrode then rotated into position against workpiece.

  2. Rolling silver nanowire electrodes: simultaneously addressing adhesion, roughness, and conductivity.

    Science.gov (United States)

    Hauger, Tate C; Al-Rafia, S M Ibrahim; Buriak, Jillian M

    2013-12-11

    Silver nanowire mesh electrodes represent a possible mass-manufacturable route toward transparent and flexible electrodes for plastic-based electronics such as organic photovoltaics (OPVs), organic light emitting diodes (OLEDs), and others. Here we describe a route that is based upon spray-coated silver nanowire meshes on polyethylene terephthalate (PET) sheets that are treated with a straightforward combination of heat and pressure to generate electrodes that have low sheet resistance, good optical transmission, that are topologically flat, and adhere well to the PET substrate. The silver nanowire meshes were prepared by spray-coating a solution of silver nanowires onto PET, in air at slightly elevated temperatures. The as-prepared silver nanowire electrodes are highly resistive due to the poor contact between the individual silver nanowires. Light pressure applied with a stainless steel rod, rolled over the as-sprayed silver nanowire meshes on PET with a speed of 10 cm s(-1) and a pressure of 50 psi, results in silver nanowire mesh arrays with sheet resistances of less than 20 Ω/□. Bending of these rolled nanowire meshes on PET with different radii of curvature, from 50 to 0.625 mm, showed no degradation of the conductivity of the electrodes, as shown by the constant sheet resistance before and after bending. Repeated bending (100 times) around a rod with a radius of curvature of 1 mm also showed no increase in the sheet resistance, demonstrating good adherence and no signs of delamination of the nanowire mesh array. The diffuse and direct transmittance of the silver nanowires (both rolled and as-sprayed) was measured for wavelengths from 350 to 1200 nm, and the diffuse transmission was similar to that of the PET substrate; the direct transmission decreases by about 7-8%. The silver nanowires were then incorporated into OPV devices with the following architecture: transparent electrode/PEDOT:PSS/P3HT:PC61BM/LiF/Al. While slightly lower in efficiency than the

  3. The lateral line microcosmos.

    Science.gov (United States)

    Ghysen, Alain; Dambly-Chaudière, Christine

    2007-09-01

    The lateral-line system is a simple sensory system comprising a number of discrete sense organs, the neuromasts, distributed over the body of fish and amphibians in species-specific patterns. Its development involves fundamental biological processes such as long-range cell migration, planar cell polarity, regeneration, and post-embryonic remodeling. These aspects have been extensively studied in amphibians by experimental embryologists, but it is only recently that the genetic bases of this development have been explored in zebrafish. This review discusses progress made over the past few years in this field.

  4. A density functional theory study of the carbon-coating effects on lithium iron borate battery electrodes

    DEFF Research Database (Denmark)

    Loftager, Simon; García Lastra, Juan Maria; Vegge, Tejs

    2016-01-01

    a density functional theory (DFT) study of the anchoring configurations of carbon coating on the LiFeBO3 electrode and its implications on the interfacial lithium diffusion. Due to large barriers associated with Li-ion diffusion through a parallel-oriented pristine graphene coating on the FeBO3 and LiFeBO3...... electrode surfaces, large structural defects in the graphene coating are required for fast Li-ion diffusion. However, such defects are expected to exist only in small concentrations due to their high formation energies. Alternative coating geometries were therefore investigated, and the configuration...

  5. A density functional theory study of the carbon-coating effects on lithium iron borate battery electrodes

    DEFF Research Database (Denmark)

    Loftager, Simon; García Lastra, Juan Maria; Vegge, Tejs

    2017-01-01

    a density functional theory (DFT) study of the anchoring configurations of carbon coating on the LiFeBO3 electrode and its implications on the interfacial lithium diffusion. Due to large barriers associated with Li-ion diffusion through a parallel-oriented pristine graphene coating on the FeBO3 and LiFeBO3...... electrode surfaces, large structural defects in the graphene coating are required for fast Li-ion diffusion. However, such defects are expected to exist only in small concentrations due to their high formation energies. Alternative coating geometries were therefore investigated, and the configuration...

  6. Creativity in later life.

    Science.gov (United States)

    Price, K A; Tinker, A M

    2014-08-01

    The ageing population presents significant challenges for the provision of social and health services. Strategies are needed to enable older people to cope within a society ill prepared for the impacts of these demographic changes. The ability to be creative may be one such strategy. This review outlines the relevant literature and examines current public health policy related to creativity in old age with the aim of highlighting some important issues. As well as looking at the benefits and negative aspects of creative activity in later life they are considered in the context of the theory of "successful ageing". Creative activity plays an important role in the lives of older people promoting social interaction, providing cognitive stimulation and giving a sense of self-worth. Furthermore, it is shown to be useful as a tool in the multi-disciplinary treatment of health problems common in later life such as depression and dementia. There are a number of initiatives to encourage older people to participate in creative activities such as arts-based projects which may range from visual arts to dance to music to intergenerational initiatives. However, participation shows geographical variation and often the responsibility of provision falls to voluntary organisations. Overall, the literature presented suggests that creative activity could be a useful tool for individuals and society. However, further research is needed to establish the key factors which contribute to patterns of improved health and well-being, as well as to explore ways to improve access to services.

  7. Brainmining emotive lateral solutions

    Directory of Open Access Journals (Sweden)

    Theodore Scaltsas

    2016-07-01

    Full Text Available BrainMining is a theory of creative thinking that shows how we should exploit the mind’s spontaneous natural disposition to use old solutions to address new problems – our Anchoring Cognitive Bias. BrainMining develops a simple and straightforward method to transform recalcitrant problems into types of problems which we have solved before, and then apply an old type of solution to them. The transformation makes the thinking lateral by matching up disparate types of problem and solution. It emphasises the role of emotive judgements that the agent makes, when she discerns whether a change of the values or the emotions and feelings in a situation, which would expand the space of solutions available for the problem at hand, would be acceptable or appropriate in the situation. A lateral solution for an intractable problem is thus spontaneously brainmined from the agent’s old solutions, to solve a transformed version of the intractable problem, possibly involving changes in the value system or the emotional profile of the situation, which the agent judges, emotively, will be acceptable, and even appropriate in the circumstances.

  8. Lateral Lumbar Interbody Fusion

    Science.gov (United States)

    Hughes, Alexander; Girardi, Federico; Sama, Andrew; Lebl, Darren; Cammisa, Frank

    2015-01-01

    The lateral lumbar interbody fusion (LLIF) is a relatively new technique that allows the surgeon to access the intervertebral space from a direct lateral approach either anterior to or through the psoas muscle. This approach provides an alternative to anterior lumbar interbody fusion with instrumentation, posterior lumbar interbody fusion, and transforaminal lumbar interbody fusion for anterior column support. LLIF is minimally invasive, safe, better structural support from the apophyseal ring, potential for coronal plane deformity correction, and indirect decompression, which have has made this technique popular. LLIF is currently being utilized for a variety of pathologies including but not limited to adult de novo lumbar scoliosis, central and foraminal stenosis, spondylolisthesis, and adjacent segment degeneration. Although early clinical outcomes have been good, the potential for significant neurological and vascular vertebral endplate complications exists. Nevertheless, LLIF is a promising technique with the potential to more effectively treat complex adult de novo scoliosis and achieve predictable fusion while avoiding the complications of traditional anterior surgery and posterior interbody techniques. PMID:26713134

  9. Capacitance enhancement via electrode patterning

    Science.gov (United States)

    Ho, Tuan A.; Striolo, Alberto

    2013-11-01

    The necessity of increasing the energy density in electric double layer capacitors to meet current demand is fueling fundamental and applied research alike. We report here molecular dynamics simulation results for aqueous electrolytes near model electrodes. Particular focus is on the effect of electrode patterning on the structure of interfacial electrolytes, and on the potential drop between the solid electrodes and the bulk electrolytes. The latter is estimated by numerically integrating the Poisson equation using the charge densities due to water and ions accumulated near the interface as input. We considered uniform and patterned electrodes, both positively and negatively charged. The uniformly charged electrodes are modeled as graphite. The patterned ones are obtained by removing carbon atoms from the top-most graphene layer, yielding nanoscopic squares and stripes patterns. For simplicity, the patterned electrodes are effectively simulated as insulators (the charge remains localized on the top-most layer of carbon atoms). Our simulations show that the patterns alter the structure of water and the accumulation of ions at the liquid-solid interfaces. Using aqueous NaCl solutions, we found that while the capacitance calculated for three positively charged electrodes did not change much, that calculated for the negatively charged electrodes significantly increased upon patterning. We find that both water structure and orientation, as well as ion accumulation affect the capacitance. As electrode patterning affects differently water structure and ion accumulation, it might be possible to observe ion-specific effects. These results could be useful for advancing our understanding of electric double layer capacitors, capacitive desalination processes, as well as of fundamental interfacial electrolytes properties.

  10. Capacitance enhancement via electrode patterning

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Tuan A.; Striolo, Alberto, E-mail: a.striolo@ucl.ac.uk [School of Chemical, Biological and Materials Engineering, The University of Oklahoma, Norman, Oklahoma 73019 (United States); Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE (United Kingdom)

    2013-11-28

    The necessity of increasing the energy density in electric double layer capacitors to meet current demand is fueling fundamental and applied research alike. We report here molecular dynamics simulation results for aqueous electrolytes near model electrodes. Particular focus is on the effect of electrode patterning on the structure of interfacial electrolytes, and on the potential drop between the solid electrodes and the bulk electrolytes. The latter is estimated by numerically integrating the Poisson equation using the charge densities due to water and ions accumulated near the interface as input. We considered uniform and patterned electrodes, both positively and negatively charged. The uniformly charged electrodes are modeled as graphite. The patterned ones are obtained by removing carbon atoms from the top-most graphene layer, yielding nanoscopic squares and stripes patterns. For simplicity, the patterned electrodes are effectively simulated as insulators (the charge remains localized on the top-most layer of carbon atoms). Our simulations show that the patterns alter the structure of water and the accumulation of ions at the liquid-solid interfaces. Using aqueous NaCl solutions, we found that while the capacitance calculated for three positively charged electrodes did not change much, that calculated for the negatively charged electrodes significantly increased upon patterning. We find that both water structure and orientation, as well as ion accumulation affect the capacitance. As electrode patterning affects differently water structure and ion accumulation, it might be possible to observe ion-specific effects. These results could be useful for advancing our understanding of electric double layer capacitors, capacitive desalination processes, as well as of fundamental interfacial electrolytes properties.

  11. Development of Pd-based membranes as hydrogen diffusion anodes

    Energy Technology Data Exchange (ETDEWEB)

    Rego, Rosa; Oliveira, M. Cristina F. [Centro de Quimica de Vila Real, Departamento de Quimica, Universidade de Tras-os-Montes e Alto Douro, Apartado 1013, Vila Real (Portugal); Esparbe, Isaac; Cabot, Pere L. [Laboartori de Ciencia i Tecnologia Electroquimica de Materials, Department de Quimica-Fisica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)

    2009-04-15

    Pd-based membranes have been prepared by Pd electroless deposition on porous stainless steel substrate and their structure, composition, morphology and thickness were analyzed by X-ray diffraction (XRD), EDS and scanning electronic microscopy (SEM). The performance of these membranes as hydrogen diffusion electrodes was evaluated in a three-electrode cell in alkaline medium. The activity towards hydrogen oxidation was high at the beginning of the experiment, but it significantly decreased with time. The major cause of this phenomenon has been attributed to the slow entry of hydrogen at the H{sub 2}/Pd interface. Even so, the technical feasibility of using these membranes as gas diffusion electrodes (GDE) has been proven. (author)

  12. Point Electrode Studies of the Solid Electrolyte-Electrode Interface

    DEFF Research Database (Denmark)

    Jacobsen, Torben

    In the development of new electrode materials for high temperature Solid Oxide Fuel Cells methods are needed for the electrochemical evaluation of the catalytic properties of the materials. A major problem in the comparison of materials is how to determine the geometry and the effective length...... of the active reaction zone, the triple phase boundary. One way of solving this is by the application of point electrodes where the electrode-electrolyte contact is assumed to be circular with a radius calculated from the high frequency impedance. The perimeter is the taken as the length of the reaction zone......$mm diameter) platinum electrodes mounted in a thin alumina tube resting on a polished 8 mol\\% yttria stabilized zirconia electrolyte at $1000^\\circ$C in air. The results where analysed in terms of the equivalent circuit $R_{YSZ}(R_r Q)$ in the frequency range 0.5MHz--1kHz. Fig.\\,1 shows...

  13. Sleeping Beauties in Meme Diffusion

    CERN Document Server

    Zhang, Leihan; Xu, Ke

    2016-01-01

    A sleeping beauty in diffusion indicates that the information, can be ideas or innovations, will experience a hibernation before a sudden spike of popularity and it is widely found in citation history of scientific publications. However, in this study, we demonstrate that the sleeping beauty is an universal phenomenon in information diffusion and even more inspiring, there exist two consecutive sleeping beauties in the entire lifetime of propagation, suggesting that the information, including trending topics, search queries or Wikipedia views, which we call memes, will go unnoticed for a period and suddenly attracts some attention, and then it falls asleep again and later wakes up with another unexpected popularity peak. Further explorations on this phenomenon show that intervals between two wake ups follow an exponential distribution and the second awakening stage generally reaches its peak at a higher velocity and will bring a wider dissemination. Taking these findings into consideration, the upgraded Bass ...

  14. Current distribution effects in AC impedance spectroscopy of electroceramic point contact and thin film model electrodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Jacobsen, Torben

    2010-01-01

    The Finite-Element-Method (FEM) was used for the simulations of the effect of a changing current distribution during AC impedance spectrum recording on electroceramic point contact and thin film model electrodes. For pure electronic conducting point contact electrodes the transition from the prim......The Finite-Element-Method (FEM) was used for the simulations of the effect of a changing current distribution during AC impedance spectrum recording on electroceramic point contact and thin film model electrodes. For pure electronic conducting point contact electrodes the transition from...... regarding its significance is provided. The associated characteristic impedance spectrum shape change is simulated and its origin discussed. Furthermore, the characteristic shape of impedance spectra of thin electroceramic film electrodes with lateral ohmic resistance is studied as a function...

  15. Spin transfer torque with spin diffusion in magnetic tunnel junctions

    KAUST Repository

    Manchon, Aurelien

    2012-08-09

    Spin transport in magnetic tunnel junctions in the presence of spin diffusion is considered theoretically. Combining ballistic tunneling across the barrier and diffusive transport in the electrodes, we solve the spin dynamics equation in the metallic layers. We show that spin diffusion mixes the transverse spin current components and dramatically modifies the bias dependence of the effective spin transfer torque. This leads to a significant linear bias dependence of the out-of-plane torque, as well as a nonconventional thickness dependence of both spin torque components.

  16. Epicondilite lateral do cotovelo

    OpenAIRE

    Cohen,Marcio; Motta Filho,Geraldo da Rocha

    2012-01-01

    A epicondilite lateral, também conhecida como cotovelo do tenista, é uma condição comum que acomete de 1 a 3% da população. O termo epicondilite sugere inflamação, embora a análise histológica tecidual não demonstre um processo inflamatório. A estrutura acometida com mais frequência é a origem do tendão extensor radial curto do carpo e o mecanismo de lesão está associado à sua sobrecarga. O tratamento incruento é o de escolha e inclui: repouso, fisioterapia, infiltração com cortisona ou plasm...

  17. Vitiligo Lateral Lower Lip

    Directory of Open Access Journals (Sweden)

    Sahoo Antaryami

    2002-01-01

    Full Text Available Vitiligo characteristically affecting the lateral lower lip (LLL is a common presentation in South Orissa. This type of lesion has rarely been described in literature. One hundred eighteen such cases were studied during the period from October 1999 to September, 2000. LLL vitiligo constituted 16.39% of all vitiligo patients. Both sexes were affected equally. The peak age of onset was in the 2nd decade, mean duration of illness 21.46 months. Fifty six patients had unilateral lesion (38 on the left and 18 on the right. Among the 62 patients having bilateral lesions, the onset was more frequent on the left (38 than either the right (8 or both sides together (16. All the patients were right handed. Association with local factors like infection, trauma, cheilitis, FDE etc were associated in 38.98% of cases, but systemic or autoimmune diseases were not associated. Positive family history was found in 22% of cases.

  18. A selective voltammetric detection for dopamine using poly(gallic acid) film modified electrode

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The electrochemistry behavior of dopamine was investigated by cyclic voltammetry and differential pulse voltammetry at a poly (gallic acid) film modified glassy carbon electrode.Two electrons and two protons participated in the diffusion-controlled electrocatalytic oxidation of dopamine with a diffusion coefficient of 2.186×10~(-5) cm~2/s.The interference of ascorbic acid with the determination of dopamine could be efficiently eliminated.This work provided a simple approach to selectively and sensitively...

  19. Note: Adhesive stamp electrodes using spider silk masks for electronic transport measurements of supra-micron sized samples

    Science.gov (United States)

    Steven, E.; Jobiliong, E.; Eugenio, P. M.; Brooks, J. S.

    2012-04-01

    A procedure for fabricating adhesive stamp electrodes based on gold coated adhesive tape used to measure electronic transport properties of supra-micron samples in the lateral range 10-100 μm and thickness >1 μm is described. The electrodes can be patterned with a ˜4 μm separation by metal deposition through a mask using Nephila clavipes spider dragline silk fibers. Ohmic contact is made by adhesive lamination of a sample onto the patterned electrodes. The performance of the electrodes with temperature and magnetic field is demonstrated for the quasi-one-dimensional organic conductor (TMTSF)2PF6 and single crystal graphite, respectively.

  20. Fractals in several electrode materials

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chunyong, E-mail: zhangchy@njau.edu.cn [Department of Chemistry, College of Science, Nanjing Agricultural University, Nanjing 210095 (China); Suzhou Key Laboratory of Environment and Biosafety, Suzhou Academy of Southeast University, Dushuhu lake higher education town, Suzhou 215123 (China); Wu, Jingyu [Department of Chemistry, College of Science, Nanjing Agricultural University, Nanjing 210095 (China); Fu, Degang [Suzhou Key Laboratory of Environment and Biosafety, Suzhou Academy of Southeast University, Dushuhu lake higher education town, Suzhou 215123 (China); State Key Laboratory of Bioelectronics, Southeast University, Nanjing 210096 (China)

    2014-09-15

    Highlights: • Fractal geometry was employed to characterize three important electrode materials. • The surfaces of all studied electrodes were proved to be very rough. • The fractal dimensions of BDD and ACF were scale dependent. • MMO film was more uniform than BDD and ACF in terms of fractal structures. - Abstract: In the present paper, the fractal properties of boron-doped diamond (BDD), mixed metal oxide (MMO) and activated carbon fiber (ACF) electrode have been studied by SEM imaging at different scales. Three materials are self-similar with mean fractal dimension in the range of 2.6–2.8, confirming that they all exhibit very rough surfaces. Specifically, it is found that MMO film is more uniform in terms of fractal structure than BDD and ACF. As a result, the intriguing characteristics make these electrodes as ideal candidates for high-performance decontamination processes.

  1. Electrochemistry at Very Small Electrodes.

    Science.gov (United States)

    1985-09-01

    Contract N00014-79-C-0862. This contract has a peculiar history. It originated in 1979. under the title "Studies in Cathodic Stripping Voltammetry and...The second category involved studies of cathodic stripping voltammetry of various materials, primarily at silver electrodes. Work carried out... Cathodic Stripping Voltammetry at a Rotating Disc Electrode", K. Shimizu and R.A. Osteryoung, February, 1981. * 4. "Electrochemical Behavior of Sulfide

  2. Heat and water transport in a polymer electrolyte fuel cell electrode

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Partha P [Los Alamos National Laboratory; Mukundan, Rangachary [Los Alamos National Laboratory; Borup, Rod L [Los Alamos National Laboratory; Ranjan, Devesh [TEXAS A& M UNIV

    2010-01-01

    In the present scenario of a global initiative toward a sustainable energy future, the polymer electrolyte fuel cell (PEFC) has emerged as one of the most promising alternative energy conversion devices for various applications. Despite tremendous progress in recent years, a pivotal performance limitation in the PEFC comes from liquid water transport and the resulting flooding phenomena. Liquid water blocks the open pore space in the electrode and the fibrous diffusion layer leading to hindered oxygen transport. The electrode is also the only component in the entire PEFC sandwich which produces waste heat from the electrochemical reaction. The cathode electrode, being the host to several competing transport mechanisms, plays a crucial role in the overall PEFC performance limitation. In this work, an electrode model is presented in order to elucidate the coupled heat and water transport mechanisms. Two scenarios are specifically considered: (1) conventional, Nafion{reg_sign} impregnated, three-phase electrode with the hydrated polymeric membrane phase as the conveyer of protons where local electro-neutrality prevails; and (2) ultra-thin, two-phase, nano-structured electrode without the presence of ionomeric phase where charge accumulation due to electro-statics in the vicinity of the membrane-CL interface becomes important. The electrode model includes a physical description of heat and water balance along with electrochemical performance analysis in order to study the influence of electro-statics/electro-migration and phase change on the PEFC electrode performance.

  3. Theory for electrochemical impedance spectroscopy of heterogeneous electrode with distributed capacitance and charge transfer resistance

    Indian Academy of Sciences (India)

    SHWETA DHILLON; RAMA KANT

    2017-08-01

    Randles-Ershler admittance model is extensively used in the modeling of batteries, fuel cells, sensors etc. It is also used in understanding response of the fundamental systems with coupled processes like charge transfer, diffusion, electric double layer charging and uncompensated solution resistance. Wegeneralize phenomenological theory for the Randles-Ershler admittance at the electrode with double layer capacitance and charge transfer heterogeneity, viz., non-uniform double layer capacitance and charge transfer resistance (c d and R CT). Electrode heterogeneity is modeled through distribution functions of R CT and c d, viz., log-normal distribution function. High frequency region captures influence of electric double layer while intermediate frequency region captures influence from the charge transfer resistance of heterogeneous electrode. A heterogeneous electrode with mean charge transfer resistance $\\bar{R CT}$ shows faster charge transfer kinetics over a electrode with uniform charge transfer resistance ($\\bar{R CT}$). It is also observed that a heterogeneous electrode having high mean with large variance in the R CT and c d can behave same as an electrode having low mean with small variance in the R CT and c d. The origin of coupling of uncompensated solution resistance (between working and reference electrode) with the charge transfer kinetics is explained. Finally, our model provides a simple route to understand the effect of spatial heterogeneity.

  4. Simulation of metallic nanostructures for emission of THz radiation using the lateral photo-Dember effect

    CERN Document Server

    McBryde, Duncan; Daniell, Geoff J; Chung, Aaron L; Mihoubi, Zakaria; Quarterman, Adrian H; Wilcox, Keith G; Tropper, Anne C; Apostolopoulos, Vasilis; 10.1109/irmmw-THz.2011.6104994

    2012-01-01

    A 2D simulation for the lateral photo-Dember effect is used to calculate the THz emission of metallic nanostructures due to ultrafast diffusion of carriers in order to realize a series of THz emitters.

  5. Microstructural Correlates of Emotional Attribution Impairment in Non-Demented Patients with Amyotrophic Lateral Sclerosis

    National Research Council Canada - National Science Library

    Crespi, Chiara; Cerami, Chiara; Dodich, Alessandra; Canessa, Nicola; Iannaccone, Sandro; Corbo, Massimo; Lunetta, Christian; Falini, Andrea; Cappa, Stefano F

    2016-01-01

    .... Thirteen individuals with either probable or definite amyotrophic lateral sclerosis and 14 healthy controls were enrolled in a Diffusion Tensor Imaging study and administered the Story-based Empathy...

  6. One-dimensional model of oxygen transport impedance accounting for convection perpendicular to the electrode

    Energy Technology Data Exchange (ETDEWEB)

    Mainka, J. [Laboratorio Nacional de Computacao Cientifica (LNCC), CMC 6097, Av. Getulio Vargas 333, 25651-075 Petropolis, RJ, Caixa Postal 95113 (Brazil); Maranzana, G.; Thomas, A.; Dillet, J.; Didierjean, S.; Lottin, O. [Laboratoire d' Energetique et de Mecanique Theorique et Appliquee (LEMTA), Universite de Lorraine, 2, avenue de la Foret de Haye, 54504 Vandoeuvre-les-Nancy (France); LEMTA, CNRS, 2, avenue de la Foret de Haye, 54504 Vandoeuvre-les-Nancy (France)

    2012-10-15

    A one-dimensional (1D) model of oxygen transport in the diffusion media of proton exchange membrane fuel cells (PEMFC) is presented, which considers convection perpendicular to the electrode in addition to diffusion. The resulting analytical expression of the convecto-diffusive impedance is obtained using a convection-diffusion equation instead of a diffusion equation in the case of classical Warburg impedance. The main hypothesis of the model is that the convective flux is generated by the evacuation of water produced at the cathode which flows through the porous media in vapor phase. This allows the expression of the convective flux velocity as a function of the current density and of the water transport coefficient {alpha} (the fraction of water being evacuated at the cathode outlet). The resulting 1D oxygen transport impedance neglects processes occurring in the direction parallel to the electrode that could have a significant impact on the cell impedance, like gas consumption or concentration oscillations induced by the measuring signal. However, it enables us to estimate the impact of convection perpendicular to the electrode on PEMFC impedance spectra and to determine in which conditions the approximation of a purely diffusive oxygen transport is valid. Experimental observations confirm the numerical results. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. First principles study of nanostructured TiS2 electrodes for Na and Mg ion storage

    Science.gov (United States)

    Li, S. N.; Liu, J. B.; Liu, B. X.

    2016-07-01

    The development of competitive Na- and Mg-ion batteries (NIBs and MIBs) with performance comparable to Li-ion batteries is hindered by the major challenge of finding advanced electrode materials. In this work, nanostructured TiS2 electrodes including nanosheets, nanoribbons and nanotubes are shown by first principles calculations to achieve improved Na and Mg ion diffusion as compared with the bulk phase. Comparative studies between Li, Na, and Mg reveal that the diffusion kinetics of Na ions would especially benefit from the nanostructure design of TiS2. More specifically, the Na ion diffusivity turns out to be considerably higher than Li ion diffusivity, which is opposite to that observed in bulk TiS2. However, in the case of Mg ions, fast diffusion is still beyond attainment since a relatively high degree of interaction is expected between Mg and the S atoms. Edge-induced modifications of diffusion properties appear in both Na and Mg ions, while the mobility of Li ions along the ribbon edges may not be as appealing. Effects of the curvature of nanotubes on the adsorption strength and ion conductivity are also explored. Our results highlight the nanostructure design as a rich playground for exploring electrodes in NIBs and MIBs.

  8. Lateral Thinking and Technology Education.

    Science.gov (United States)

    Waks, Shlomo

    1997-01-01

    Presents an analysis of technology education and its relevance to lateral thinking. Discusses prospects for utilizing technology education as a platform and a contextual domain for nurturing lateral thinking. Argues that technology education is an appropriate environment for developing complementary incorporation of vertical and lateral thinking.…

  9. Structural optimization of 3D porous electrodes for high-rate performance lithium ion batteries.

    Science.gov (United States)

    Ye, Jianchao; Baumgaertel, Andreas C; Wang, Y Morris; Biener, Juergen; Biener, Monika M

    2015-02-24

    Much progress has recently been made in the development of active materials, electrode morphologies and electrolytes for lithium ion batteries. Well-defined studies on size effects of the three-dimensional (3D) electrode architecture, however, remain to be rare due to the lack of suitable material platforms where the critical length scales (such as pore size and thickness of the active material) can be freely and deterministically adjusted over a wide range without affecting the overall 3D morphology of the electrode. Here, we report on a systematic study on length scale effects on the electrochemical performance of model 3D np-Au/TiO2 core/shell electrodes. Bulk nanoporous gold provides deterministic control over the pore size and is used as a monolithic metallic scaffold and current collector. Extremely uniform and conformal TiO2 films of controlled thickness were deposited on the current collector by employing atomic layer deposition (ALD). Our experiments demonstrate profound performance improvements by matching the Li(+) diffusivity in the electrolyte and the solid state through adjusting pore size and thickness of the active coating which, for 200 μm thick porous electrodes, requires the presence of 100 nm pores. Decreasing the thickness of the TiO2 coating generally improves the power performance of the electrode by reducing the Li(+) diffusion pathway, enhancing the Li(+) solid solubility, and minimizing the voltage drop across the electrode/electrolyte interface. With the use of the optimized electrode morphology, supercapacitor-like power performance with lithium-ion-battery energy densities was realized. Our results provide the much-needed fundamental insight for the rational design of the 3D architecture of lithium ion battery electrodes with improved power performance.

  10. Determination of diffuse double layer protonation constants for hydrous ferric oxide (HFO): supporting evidence for the Dzombak and Morel compilation

    CSIR Research Space (South Africa)

    Pretorius, PJ

    1998-01-01

    Full Text Available The acid-base properties of hydrous ferric oxide were studied by glass electrode potentiometry. From the potentiometric data, surface protonation constants were derived according to the Diffuse Double Layer convention. Chemical equilibrium modelling...

  11. A density functional theory study of the carbon-coating effects on lithium iron borate battery electrodes.

    Science.gov (United States)

    Loftager, Simon; García-Lastra, Juan María; Vegge, Tejs

    2017-01-18

    Lithium iron borate (LiFeBO3) is a promising cathode material due to its high theoretical specific capacity, inexpensive components and small volume change during operation. Yet, challenges related to severe air- and moisture-induced degradation have prompted the utilization of a protective coating on the electrode which also improves the electronic conductivity. However, not much is known about the preferential geometries of the coating as well as how these coating-electrode interfaces influence the lithium diffusion between the coating and the electrode. Here, we therefore present a density functional theory (DFT) study of the anchoring configurations of carbon coating on the LiFeBO3 electrode and its implications on the interfacial lithium diffusion. Due to large barriers associated with Li-ion diffusion through a parallel-oriented pristine graphene coating on the FeBO3 and LiFeBO3 electrode surfaces, large structural defects in the graphene coating are required for fast Li-ion diffusion. However, such defects are expected to exist only in small concentrations due to their high formation energies. Alternative coating geometries were therefore investigated, and the configuration in which the coating layers were anchored normal to the electrode surface at B and O atoms was found to be most stable. Nudged elastic band (NEB) calculations of the lithium diffusion barriers across the interface between the optimally oriented coating layers and the electrode show no kinetic limitations for lithium extraction and insertion. Additionally, this graphite-coating configuration showed partial blocking of electrode-degrading species.

  12. Stimulation and recording electrodes for neural prostheses

    CERN Document Server

    Pour Aryan, Naser; Rothermel, Albrecht

    2015-01-01

    This book provides readers with basic principles of the electrochemistry of the electrodes used in modern, implantable neural prostheses. The authors discuss the boundaries and conditions in which the electrodes continue to function properly for long time spans, which are required when designing neural stimulator devices for long-term in vivo applications. Two kinds of electrode materials, titanium nitride and iridium are discussed extensively, both qualitatively and quantitatively. The influence of the counter electrode on the safety margins and electrode lifetime in a two electrode system is explained. Electrode modeling is handled in a final chapter.

  13. Implanted electrodes for multi-month EEG.

    Science.gov (United States)

    Jochum, Thomas; Engdahl, Susannah; Kolls, Brad J; Wolf, Patrick

    2014-01-01

    An implanted electroencephalogram (EEG) recorder would help diagnose infrequent seizure-like events. A proof-of-concept study quantified the electrical characteristics of the electrodes planned for the proposed recorder. The electrodes were implanted in an ovine model for eight weeks. Electrode impedance was less than 800 Ohms throughout the study. A frequency-domain determination of sedation performed similarly for surface versus implanted electrodes throughout the study. The time-domain correlation between an implanted electrode and a surface electrode was almost as high as between two surface electrodes (0.86 versus 0.92). EEG-certified clinicians judged that the implanted electrode quality was adequate to excellent and that the implanted electrodes provided the same clinical information as surface electrodes except for a noticeable amplitude difference. No significant issues were found that would stop development of the EEG recorder.

  14. Different electrode configurations to optimize performance of multi-electrode microbial fuel cells for generating power or treating domestic wastewater

    KAUST Repository

    Ahn, Yongtae

    2014-03-01

    Scaling-up of microbial fuel cells (MFCs) for practical applications requires compact, multiple-electrode designs. Two possible configurations are a separator electrode assembly (SEA) or closely spaced electrodes (SPA) that lack a separator. It is shown here that the optimal configuration depends on whether the goal is power production or rate of wastewater treatment. SEA MFCs produced a 16% higher maximum power density (328 ± 11 mW m-2) than SPA MFCs (282 ± 29 mW m-2), and higher coulombic efficiencies (SEAs, 9-31%; SPAs, 2-23%) with domestic wastewater. However, treatment was accomplished in only 12 h with the SPA MFC, compared to 36 h with the SEA configuration. Ohmic resistance was not a main factor in performance as this component contributed only 4-7% of the total internal resistance. Transport simulations indicated that hindered oxygen diffusion into the SEA reactor was the primary reason for the increased treatment time. However, a reduction in the overall rate of substrate diffusion also may contribute to the long treatment time with the SEA reactor. These results suggest that SEA designs can more effectively capture energy from wastewater, but SPA configurations will be superior in terms of treatment efficiency due to a greatly reduced time needed for treatment. © 2013 Elsevier B.V. All rights reserved.

  15. Superior electrode performance of mesoporous hollow TiO2 microspheres through efficient hierarchical nanostructures

    Science.gov (United States)

    Zhang, Feng; Zhang, Yu; Song, Shuyan; Zhang, Hongjie

    2011-10-01

    Mesoporous hollow TiO2 microspheres with controlled size and hierarchical nanostructures are designed from a process employing in suit template-assisted and hydrothermal methods. The results show that the hollow microspheres composed of mesoporous nanospheres possess very stable reversible capacity of 184 mAh g-1 at 0.25C and exhibit extremely high power of 122 mAh g-1 at the high rate of 10C. The superior high-rate and high-capacity performance of the sample is attributed to the efficient hierarchical nanostructures. The hollow structure could shorten the diffusion length for lithium ion in the microspheres. The large mesoporous channels between the mesoporous nanospheres provide an easily-accessed system which facilitates electrolyte transportation and lithium ion diffusion within the electrode materials. The electrolyte, flooding the mesoporous channels, can also lead to a high electrolyte/electrode contact area, facilitating transport of lithium ions across the electrolyte/electrode interface. The small mesopores in the meosporous nanospheres can make the electrolyte and lithium ion further diffuse into the interior of electrode materials and increase electrolyte/electrode contact area. The small nanoparticles can also ensure high reversible capacity.

  16. [Lateral lumbar disk hernia].

    Science.gov (United States)

    Monod, A; Desmoineaux, P; Deburge, A

    1990-01-01

    Lateral lumbar disc herniations (L.D.H.) develop in the foramen, and compress the nerve root against the overlying vertebral pedicle. In our study of L.D.H. from the clinical, radiographical, and therapeutical aspects, we reviewed 23 cases selected from the 590 patients treated for discal herniation from 1984 to 1987. The frequency of L.D.H. in this series was 3.8 per cent. The clinical pattern brings out some suggestive signs of L.D.H. (frequency of cruralgia, a seldom very positive Lasegue's test, the paucity of spinal signs, non impulsive pain). Saccoradiculography and discography rarely evidenced the L.D.H.. The T.D.M. was the investigation of choice on condition that it was correctly used. When the image was doubtful, disco-CT confirmation should be proceeded too. This latter method of investigation enabled the possibility of sequestration to be explored. 14 patients were treated by chemonucleolysis, with 9 successful outcomes. The 5 failures were cases where chemonucleolysis should not have been indicated, mainly due to associated osseous stenosis. 9 patients underwent immediate surgery with good results in each case.

  17. Amyotrophic lateral sclerosis: update

    Directory of Open Access Journals (Sweden)

    Zapata-Zapata, Carlos Hugo

    2016-04-01

    Full Text Available Amyotrophic lateral sclerosis is a neurodegenerative disease with devastating consequences for the patient and his/her family. Its etiology is still not clear. In about 10 % of the patients there is a hereditary pattern of the disease. Worldwide, prevalence ranges from 2 to 11 cases per 100,000 people. Age of presentation varies from 58 to 63 years for sporadic cases, and from 47 to 52 years for the familial ones. Concerning gender, there is a slight preference for males. Clinical manifestations include signs of upper and lower motor neurons, damage in limbs and bulbar muscles, and, in some patients, frontotemporal cognitive dysfunction. Diagnosis is essentially clinical supported by neurophysiological studies, such as needle electromyography, which is the most important test for early diagnosis. There is no cure, but riluzol has proven to delay the use of mechanical ventilation and to slightly prolong survival. Consequently, management is based on support measures, such as those related to nutrition and ventilatory function, in addition to control of the motor and non-motor symptoms of the disease.

  18. Extraction electrode geometry for a calutron

    Science.gov (United States)

    Veach, A.M.; Bell, W.A. Jr.

    1975-09-23

    This patent relates to an improved geometry for the extraction electrode and the ground electrode utilized in the operation of a calutron. The improved electrodes are constructed in a partial-picture-frame fashion with the slits of both electrodes formed by two tungsten elongated rods. Additional parallel spaced-apart rods in each electrode are used to establish equipotential surfaces over the rest of the front of the ion source. (auth)

  19. Diffusion and exchange of adsorbed polymers studied by Monte Carlo simulations

    NARCIS (Netherlands)

    Klein Wolterink, J.; Barkema, G.T.; Cohen Stuart, M.A.

    2005-01-01

    Monte Carlo simulations are performed of adsorbed polymers with various polymer lengths N and adsorption energies ¿s. Exchange times and the rates of lateral diffusion (along the surface) are investigated as a function of N and ¿s. Lateral diffusion is found to be a combination of reptation (diffusi

  20. Synthesis and characterization of nanostructured electrodes for solid state ionic devices

    Science.gov (United States)

    Zhang, Yuelan

    Solid-state electrochemical energy conversion and storage technologies such as fuel cells and lithium ion batteries will influence the way we use energy and the environment we live in. The demands for advanced power sources with high energy efficiency, minimum environmental impact, and low cost have been the impetus for the development of a new generation of batteries and fuel cells. Currently, lithium ion battery technology's greatest disadvantages are long-term cycling stability and high charge/discharge rate capabilities. On the other hand, fuel cell technology's greatest disadvantage is cost. It is found that these problems could be attenuated by the incorporation of nano-structured materials. But, we are still far away from possessing a solid scientific understanding of what goes on at the nanoscale inside these solid state ionic devices, and what is the relationship between nano-structures and their electrochemical properties, especially between the microstructure and electrode polarization and degradation. Electrode polarization represents a voltage loss in an electrochemical energy conversion process. Such understanding is critical for further progress in solid state ionic devices. This thesis focused on the design, fabrication, and characterization of nanostructured porous electrodes with desired composition and microstructure to minimize electrode polarization losses in the application of fuel cells and lithium ion batteries. Various chemical methods such as sol-gel, hydrothermal, surfactant, colloidal and polymer template-assisted processes have been applied in this work. And various characterization techniques have been used to explore the understanding of the microscopic features with electrochemical interfacial properties of the electrodes. Solid-state diffusion often limits the utilization and rate capability of electrode materials in a lithium-ion battery, especially at high charge/discharge rates. When the fluxes of Li+ insertion or extraction

  1. Diffusion on spatial network

    Science.gov (United States)

    Hui, Zi; Tang, Xiaoyue; Li, Wei; Greneche, Jean-Marc; Wang, Qiuping A.

    2015-04-01

    In this work, we study the problem of diffusing a product (idea, opinion, disease etc.) among agents on spatial network. The network is constructed by random addition of nodes on the planar. The probability for a previous node to be connected to the new one is inversely proportional to their spatial distance to the power of α. The diffusion rate between two connected nodes is inversely proportional to their spatial distance to the power of β as well. Inspired from the Fick's first law, we introduce the diffusion coefficient to measure the diffusion ability of the spatial network. Using both theoretical analysis and Monte Carlo simulation, we get the fact that the diffusion coefficient always decreases with the increasing of parameter α and β, and the diffusion sub-coefficient follows the power-law of the spatial distance with exponent equals to -α-β+2. Since both short-range diffusion and long-range diffusion exist, we use anomalous diffusion method in diffusion process. We get the fact that the slope index δ in anomalous diffusion is always smaller that 1. The diffusion process in our model is sub-diffusion.

  2. Induction of Polymerization of the Surface Nanostructures of the Electrodes by Electric Field

    Directory of Open Access Journals (Sweden)

    S.G. Еmelyanov

    2014-07-01

    Full Text Available The results of experimental studies of the interface of "dielectric liquid - nanostructured metal electrode" after electroconvection is presented. It is discovered the patterns of structuring of areas of polymerization showing disruption of the diffusion layer and the processes of charge injection from the tops of structures.

  3. High surface area carbon for bifunctional air electrodes applied in zinc-air batteries

    Energy Technology Data Exchange (ETDEWEB)

    Arai, H. [on leave from NTT Laboratories (Japan); Mueller, S.; Haas, O. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    Bifunctional air electrodes with high surface area carbon substrates showed low reduction overpotential, thus are promising for enhancing the energy efficiency and power capability of zinc-air batteries. The improved performance is attributed to lower overpotential due to diffusion of the reaction intermediate, namely the peroxide ion. (author) 1 fig., 2 refs.

  4. Electrokinetic and impedimetric dynamics of FeCo-nanoparticles on glassy carbon electrode

    CSIR Research Space (South Africa)

    Ikpo, CO

    2013-01-01

    Full Text Available voltammetric experiments revealed a diffusion-controlled electron transfer process on the GCE/FeCo electrode surface. Further interrogation on the electrochemical properties of the FeCo nanoelectrode in an oxygen saturated 1 M LiClO4 containing 1:1 v/v ethylene...

  5. Surface concentration nonuniformities resulting from chronoamperometry of a reversible reaction at an ultramicrodisk electrode

    DEFF Research Database (Denmark)

    Britz, Dieter H.; Strutwolf, Jörg

    2016-01-01

    The chronoamperometric experiment at a disk electrode was simulated, assuming a reversible reaction. When the diffusion coefficients of the two substances involved are different, there appears a surface concentration non- uniformity in the radial direction, exhibiting a maximum effect in time. At...

  6. Evaluation of kinetic parameters and redox mechanism of quinoxaline at glassy carbon electrode

    Directory of Open Access Journals (Sweden)

    Aleksić Mara M.

    2014-01-01

    Full Text Available The electrochemical behavior of a biologically important heterocyclic compound quinoxaline (QUI was investigated by cyclic voltammetry (CV in solutions of differing pH, using a glassy carbon electrode (GCE. The reduction of QUI occurs as a quasi-reversible reaction in acid medium, reaching reversibility in alkaline solutions. The kinetic parameters of the electrode process such as αnα, diffusion coefficient (D and heterogeneous rate constant (ks, were evaluated and discussed. Redox mechanism of QUI was proposed on the basis of experimental results. Reduction process involves a transfer of two electrons and two protons at the pyrazine ring of QUI forming a dihydro-derivative. In acid solutions, the product of QUI reduction undergoes irreversible oxidation in a one-electron process. The electrode processes was found to be diffusion controlled. [Projekat Ministarstva nauke Republike Srbije, br. 172033

  7. The dependence of natural graphite anode performance on electrode density

    Energy Technology Data Exchange (ETDEWEB)

    Shim, Joongpyo; Striebel, Kathryn A.

    2003-11-01

    The effect of electrode density for lithium intercalation and irreversible capacity loss on the natural graphite anode in lithium ion batteries was studied by electrochemical methods. Both the first-cycle reversible and irreversible capacities of the natural graphite anode decreased with an increase in the anode density though compression. The reduction in reversible capacity was attributed to a reduction in the chemical diffusion coefficient for lithium though partially agglomerated particles with a larger stress. For the natural graphite in this study the potentials for Li (de)insertion shifted between the first and second formation cycles and the extent of this shift was dependent on electrode density. The relation between this peak shift and the irreversible capacity loss are probably both due to the decrease in graphite surface area with compression.

  8. Nonlinear Dynamics of Capacitive Charging and Desalination by Porous Electrodes

    CERN Document Server

    Biesheuvel, P M

    2009-01-01

    The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by super-capacitors, water desalination and purification by capacitive deionization (or desalination), and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or specific adsorption of ions) in the limit of thin double layers (compared to typical pore dimensions). We illustrate the theory in the case of a dilute, symmetric, binary electrolyte using the Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae are available for salt adsorption and capacitive charging of the diffuse part of the double layer. We solve the full GCS mean-field theory numerically for realistic parameters in capacitive deionization, and we derive reduced models for two limiting regimes wi...

  9. Diamond heteroepitaxial lateral overgrowth

    Science.gov (United States)

    Tang, Yung-Hsiu

    This dissertation describes improvements in the growth of single crystal diamond by microwave plasma-assisted chemical vapor deposition (CVD). Heteroepitaxial (001) diamond was grown on 1 cm. 2 a-plane sapphiresubstrates using an epitaxial (001) Ir thin-film as a buffer layer. Low-energy ion bombardment of the Ir layer, a process known as bias-enhanced nucleation, is a key step in achieving a high density of diamond nuclei. Bias conditions were optimized to form uniformly-high nucleation densities across the substrates, which led to well-coalesced diamond thin films after short growth times. Epitaxial lateral overgrowth (ELO) was used as a means of decreasing diamond internal stress by impeding the propagation of threading dislocations into the growing material. Its use in diamond growth requires adaptation to the aggressive chemical and thermal environment of the hydrogen plasma in a CVD reactor. Three ELO variants were developed. The most successful utilized a gold (Au) mask prepared by vacuum evaporation onto the surface of a thin heteroepitaxial diamond layer. The Au mask pattern, a series of parallel stripes on the micrometer scale, was produced by standard lift-off photolithography. When diamond overgrows the mask, dislocations are largely confined to the substrate. Differing degrees of confinement were studied by varying the stripe geometry and orientation. Significant improvement in diamond quality was found in the overgrown regions, as evidenced by reduction of the Raman scattering linewidth. The Au layer was found to remain intact during diamond overgrowth and did not chemically bond with the diamond surface. Besides impeding the propagation of threading dislocations, it was discovered that the thermally-induced stress in the CVD diamond was significantly reduced as a result of the ductile Au layer. Cracking and delamination of the diamond from the substrate was mostly eliminated. When diamond was grown to thicknesses above 0.1 mm it was found that

  10. Imaging Findings Associated with Cognitive Performance in Primary Lateral Sclerosis and Amyotrophic Lateral Sclerosis

    Directory of Open Access Journals (Sweden)

    Avner Meoded

    2013-08-01

    Full Text Available Introduction: Executive dysfunction occurs in many patients with amyotrophic lateral sclerosis (ALS, but it has not been well studied in primary lateral sclerosis (PLS. The aims of this study were to (1 compare cognitive function in PLS to that in ALS patients, (2 explore the relationship between performance on specific cognitive tests and diffusion tensor imaging (DTI metrics of white matter tracts and gray matter volumes, and (3 compare DTI metrics in patients with and without cognitive and behavioral changes. Methods: The Delis-Kaplan Executive Function System (D-KEFS, the Mattis Dementia Rating Scale (DRS-2, and other behavior and mood scales were administered to 25 ALS patients and 25 PLS patients. Seventeen of the PLS patients, 13 of the ALS patients, and 17 healthy controls underwent structural magnetic resonance imaging (MRI and DTI. Atlas-based analysis using MRI Studio software was used to measure fractional anisotropy, and axial and radial diffusivity of selected white matter tracts. Voxel-based morphometry was used to assess gray matter volumes. The relationship between diffusion properties of selected association and commissural white matter and performance on executive function and memory tests was explored using a linear regression model. Results: More ALS than PLS patients had abnormal scores on the DRS-2. DRS-2 and D-KEFS scores were related to DTI metrics in several long association tracts and the callosum. Reduced gray matter volumes in motor and perirolandic areas were not associated with cognitive scores. Conclusion: The changes in diffusion metrics of white matter long association tracts suggest that the loss of integrity of the networks connecting fronto-temporal areas to parietal and occipital areas contributes to cognitive impairment.

  11. LATERAL SURVIVAL: AN OT ACCOUNT

    Directory of Open Access Journals (Sweden)

    Moira Yip

    2004-12-01

    Full Text Available When laterals are the targets of phonological processes, laterality may or may not survive. In a fixed feature geometry, [lateral] should be lost if its superordinate node is eliminated by either the spreading of a neighbouring node, or by coda neutralization. So if [lateral] is under Coronal (Blevins 1994, it should be lost under Place assimilation, and if [lateral] is under Sonorant Voicing (Rice & Avery 1991 it should be lost by rules that spread voicing. Yet in some languages lateral survives such spreading intact. Facts like these argue against a universal attachment of [lateral] under either Coronal or Sonorant Voicing, and in favour of an account in terms of markedness constraints on feature-co-occurrence (Padgett 2000. The core of an OT account is that IFIDENTLAT is ranked above whatever causes neutralization, such as SHARE-F or *CODAF. laterality will survive. If these rankings are reversed, we derive languages in which laterality is lost. The other significant factor is markedness. High-ranked feature co-occurrence constraints like *LATDORSAL can block spreading from affecting laterals at all.

  12. A Student Diffusion Activity

    Science.gov (United States)

    Kutzner, Mickey; Pearson, Bryan

    2017-01-01

    Diffusion is a truly interdisciplinary topic bridging all areas of STEM education. When biomolecules are not being moved through the body by fluid flow through the circulatory system or by molecular motors, diffusion is the primary mode of transport over short distances. The direction of the diffusive flow of particles is from high concentration…

  13. Acoustic diffusers III

    Science.gov (United States)

    Bidondo, Alejandro

    2002-11-01

    This acoustic diffusion research presents a pragmatic view, based more on effects than causes and 15 very useful in the project advance control process, where the sound field's diffusion coefficient, sound field diffusivity (SFD), for its evaluation. Further research suggestions are presented to obtain an octave frequency resolution of the SFD for precise design or acoustical corrections.

  14. A Student Diffusion Activity

    Science.gov (United States)

    Kutzner, Mickey; Pearson, Bryan

    2017-02-01

    Diffusion is a truly interdisciplinary topic bridging all areas of STEM education. When biomolecules are not being moved through the body by fluid flow through the circulatory system or by molecular motors, diffusion is the primary mode of transport over short distances. The direction of the diffusive flow of particles is from high concentration toward low concentration.

  15. Numerical modeling of mantle plume diffusion

    Science.gov (United States)

    Krupsky, D.; Ismail-Zadeh, A.

    2004-12-01

    To clarify the influence of the heat diffusion on the mantle plume evolution, we develop a two-dimensional numerical model of the plume diffusion and relevant efficient numerical algorithm and code to compute the model. The numerical approach is based on the finite-difference method and modified splitting algorithm. We consider both von Neumann and Direchlet conditions at the model boundaries. The thermal diffusivity depends on pressure in the model. Our results show that the plume is disappearing from the bottom up - the plume tail at first and its head later - because of the mantle plume geometry (a thin tail and wide head) and higher heat conductivity in the lower mantle. We study also an effect of a lateral mantle flow associated with the plate motion on the distortion of the diffusing mantle plume. A number of mantle plumes recently identified by seismic tomography seem to disappear in the mid-mantle. We explain this disappearance as the effect of heat diffusion on the evolution of mantle plume.

  16. Amyotrophic lateral sclerosis

    Directory of Open Access Journals (Sweden)

    Leigh P Nigel

    2009-02-01

    Full Text Available Abstract Amyotrophic lateral sclerosis (ALS is a neurodegenerative disease characterised by progressive muscular paralysis reflecting degeneration of motor neurones in the primary motor cortex, corticospinal tracts, brainstem and spinal cord. Incidence (average 1.89 per 100,000/year and prevalence (average 5.2 per100,000 are relatively uniform in Western countries, although foci of higher frequency occur in the Western Pacific. The mean age of onset for sporadic ALS is about 60 years. Overall, there is a slight male prevalence (M:F ratio~1.5:1. Approximately two thirds of patients with typical ALS have a spinal form of the disease (limb onset and present with symptoms related to focal muscle weakness and wasting, where the symptoms may start either distally or proximally in the upper and lower limbs. Gradually, spasticity may develop in the weakened atrophic limbs, affecting manual dexterity and gait. Patients with bulbar onset ALS usually present with dysarthria and dysphagia for solid or liquids, and limbs symptoms can develop almost simultaneously with bulbar symptoms, and in the vast majority of cases will occur within 1–2 years. Paralysis is progressive and leads to death due to respiratory failure within 2–3 years for bulbar onset cases and 3–5 years for limb onset ALS cases. Most ALS cases are sporadic but 5–10% of cases are familial, and of these 20% have a mutation of the SOD1 gene and about 2–5% have mutations of the TARDBP (TDP-43 gene. Two percent of apparently sporadic patients have SOD1 mutations, and TARDBP mutations also occur in sporadic cases. The diagnosis is based on clinical history, examination, electromyography, and exclusion of 'ALS-mimics' (e.g. cervical spondylotic myelopathies, multifocal motor neuropathy, Kennedy's disease by appropriate investigations. The pathological hallmarks comprise loss of motor neurones with intraneuronal ubiquitin-immunoreactive inclusions in upper motor neurones and TDP-43

  17. Electrocatalysis for oxygen electrodes in fuel cells and water electrolyzers for space applications

    Science.gov (United States)

    Prakash, Jai; Tryk, Donald; Yeager, Ernest

    1990-01-01

    The lead ruthenate pyrochlore Pb2Ru2O6.5, in both high- and low-area forms, has been characterized using thermogravimetric analysis, X-ray photoelectron spectroscopy, X-ray diffraction, cyclic voltammetry, and O2 reduction and generation kinetic-mechanistic studies. Mechanisms are proposed. Compounds in which part of the Ru is substituted with Ir have also been prepared. They exhibit somewhat better performance for O2 reduction in porous, gas-fed electrodes than the unsubstituted compound. The anodic corrosion resistance of pyrochlore-based porous electrodes was improved by using two different anionically conducting polymer overlayers, which slow down the diffusion of ruthenate and plumbate out of the electrode. The O2 generation performance was improved with both types of electrodes. With a hydrogel overlayer, the O2 reduction performance was also improved.

  18. Tonoplast Aquaporins Facilitate Lateral Root Emergence.

    Science.gov (United States)

    Reinhardt, Hagen; Hachez, Charles; Bienert, Manuela Désirée; Beebo, Azeez; Swarup, Kamal; Voß, Ute; Bouhidel, Karim; Frigerio, Lorenzo; Schjoerring, Jan K; Bennett, Malcolm J; Chaumont, Francois

    2016-03-01

    Aquaporins (AQPs) are water channels allowing fast and passive diffusion of water across cell membranes. It was hypothesized that AQPs contribute to cell elongation processes by allowing water influx across the plasma membrane and the tonoplast to maintain adequate turgor pressure. Here, we report that, in Arabidopsis (Arabidopsis thaliana), the highly abundant tonoplast AQP isoforms AtTIP1;1, AtTIP1;2, and AtTIP2;1 facilitate the emergence of new lateral root primordia (LRPs). The number of lateral roots was strongly reduced in the triple tip mutant, whereas the single, double, and triple tip mutants showed no or minor reduction in growth of the main root. This phenotype was due to the retardation of LRP emergence. Live cell imaging revealed that tight spatiotemporal control of TIP abundance in the tonoplast of the different LRP cells is pivotal to mediating this developmental process. While lateral root emergence is correlated to a reduction of AtTIP1;1 and AtTIP1;2 protein levels in LRPs, expression of AtTIP2;1 is specifically needed in a restricted cell population at the base, then later at the flanks, of developing LRPs. Interestingly, the LRP emergence phenotype of the triple tip mutants could be fully rescued by expressing AtTIP2;1 under its native promoter. We conclude that TIP isoforms allow the spatial and temporal fine-tuning of cellular water transport, which is critically required during the highly regulated process of LRP morphogenesis and emergence.

  19. RETGEM with polyvinylchloride (PVC) electrodes

    CERN Document Server

    Razin, V I; Reshetin, A I; Filippov, S N

    2009-01-01

    This paper presents a new design of the RETGEM (Resistive Electrode Thick GEM) based on electrodes made of a polyvinylchloride material (PVC). Our device can operate with gains of 10E5 as a conventional TGEM at low counting rates and as RPC in the case of high counting rates without of the transit to the violent sparks. The distinct feature of present RETGEM is the absent of the metal coating and lithographic technology for manufacturing of the protective dielectric rms. The electrodes from PVC permit to do the holes by a simple drilling machine. Detectors on a RETGEM basis could be useful in many fields of an application requiring a more cheap manufacturing and safe operation, for example, in a large neutrino experiments, in TPC, RICH systems.

  20. Composite Electrodes for Electrochemical Supercapacitors

    Directory of Open Access Journals (Sweden)

    Yang QuanMin

    2010-01-01

    Full Text Available Abstract Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 4–6 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNT into porous Ni plaque current collectors. Obtained composite electrodes, containing 85% of manganese dioxide and 15 mass% of MWCNT, as a conductive additive, with total mass loading of 7–15 mg cm−2, showed a capacitive behavior in 0.5-M Na2SO4 solutions. The decrease in stirring time during precipitation of the nanofibers resulted in reduced agglomeration and higher specific capacitance (SC. The highest SC of 185 F g−1 was obtained at a scan rate of 2 mV s−1 for mass loading of 7 mg cm−2. The SC decreased with increasing scan rate and increasing electrode mass.

  1. Multiplexed DNA-modified electrodes.

    Science.gov (United States)

    Slinker, Jason D; Muren, Natalie B; Gorodetsky, Alon A; Barton, Jacqueline K

    2010-03-03

    We report the use of silicon chips with 16 DNA-modified electrodes (DME chips) utilizing DNA-mediated charge transport for multiplexed detection of DNA and DNA-binding protein targets. Four DNA sequences were simultaneously distinguished on a single DME chip with 4-fold redundancy, including one incorporating a single base mismatch. These chips also enabled investigation of the sequence-specific activity of the restriction enzyme Alu1. DME chips supported dense DNA monolayer formation with high reproducibility, as confirmed by statistical comparison to commercially available rod electrodes. The working electrode areas on the chips were reduced to 10 microm in diameter, revealing microelectrode behavior that is beneficial for high sensitivity and rapid kinetic analysis. These results illustrate how DME chips facilitate sensitive and selective detection of DNA and DNA-binding protein targets in a robust and internally standardized multiplexed format.

  2. Neural stimulation and recording electrodes.

    Science.gov (United States)

    Cogan, Stuart F

    2008-01-01

    Electrical stimulation of nerve tissue and recording of neural electrical activity are the basis of emerging prostheses and treatments for spinal cord injury, stroke, sensory deficits, and neurological disorders. An understanding of the electrochemical mechanisms underlying the behavior of neural stimulation and recording electrodes is important for the development of chronically implanted devices, particularly those employing large numbers of microelectrodes. For stimulation, materials that support charge injection by capacitive and faradaic mechanisms are available. These include titanium nitride, platinum, and iridium oxide, each with certain advantages and limitations. The use of charge-balanced waveforms and maximum electrochemical potential excursions as criteria for reversible charge injection with these electrode materials are described and critiqued. Techniques for characterizing electrochemical properties relevant to stimulation and recording are described with examples of differences in the in vitro and in vivo response of electrodes.

  3. Evaluation of diffuse lung uptake in radiogallium scans

    Energy Technology Data Exchange (ETDEWEB)

    Kamei, Tetsuya (Toyama Medical and Pharmaceutical Univ. (Japan). Faculty of Medicine); Tatsuno, Ikuo

    1982-08-01

    Diffuse lung uptake of radiogallium was observed in 12 of 239 scans (5.0%). All of 12 patients received radiation therapy (average dose: 34Gy) and 9 of 12 patients were also placed on chemotherapy (average duration: 7 weeks). The most common cause of diffuse lung uptake was infection which included interstitial pneumonitis and the second was pleuritis. Of the 12 patients, 7 patients died an average of 3.6 months later since diffuse lung uptake was observed. Therefore, when we recognize diffuse lung uptake, we must perform closer examination and appropriate therapy as early as possible.

  4. Septins and the lateral compartmentalization of eukaryotic membranes.

    Science.gov (United States)

    Caudron, Fabrice; Barral, Yves

    2009-04-01

    Eukaryotic cells from neurons and epithelial cells to unicellular fungi frequently rely on cellular appendages such as axons, dendritic spines, cilia, and buds for their biology. The emergence and differentiation of these appendages depend on the formation of lateral diffusion barriers at their bases to insulate their membranes from the rest of the cell. Here, we review recent progress regarding the molecular mechanisms and functions of such barriers. This overview underlines the importance and conservation of septin-dependent diffusion barriers, which coordinately compartmentalize both plasmatic and internal membranes. We discuss their role in memory establishment and the control of cellular aging.

  5. Protected electrode structures and methods

    Energy Technology Data Exchange (ETDEWEB)

    Mikhaylik, Yuriy V.; Laramie, Michael G.; Kopera, John Joseph Christopher

    2017-08-08

    An electrode structure and its method of manufacture are disclosed. The disclosed electrode structures may be manufactured by depositing a first release layer on a first carrier substrate. A first protective layer may be deposited on a surface of the first release layer and a first electroactive material layer may then be deposited on the first protective layer. The first release layer may have a low mean peak to valley surface roughness, which may enable the formation of a thin protective layer with a low mean peak to valley surface roughness.

  6. Nanoengineered membrane electrode assembly interface

    Science.gov (United States)

    Song, Yujiang; Shelnutt, John A

    2013-08-06

    A membrane electrode structure suitable for use in a membrane electrode assembly (MEA) that comprises membrane-affixed metal nanoparticles whose formation is controlled by a photochemical process that controls deposition of the metal nanoparticles using a photocatalyst integrated with a polymer electrolyte membrane, such as an ionomer membrane. Impregnation of the polymer membrane with the photocatalyst prior to metal deposition greatly reduces the required amount of metal precursor in the deposition reaction solution by restricting metal reduction substantially to the formation of metal nanoparticles affixed on or near the surface of the polymer membrane with minimal formation of metallic particles not directly associated with the membrane.

  7. Gallium nitride electrodes for membrane-based electrochemical biosensors.

    Science.gov (United States)

    Schubert, T; Steinhoff, G; von Ribbeck, H-G; Stutzmannn, M; Eickhoff, M; Tanaka, M

    2009-10-01

    We report on the deposition of planar lipid bilayers (supported membranes) on gallium nitride (GaN) electrodes for potential applications as membrane-based biosensors. The kinetics of the lipid membrane formation upon vesicle fusion were monitored by simultaneous measurements of resistance and capacitance of the membrane using AC impedance spectroscopy in the frequency range between 50 mHz and 50 kHz. We could identify a two-step process of membrane spreading and self-healing. Despite its relatively low resistance, the membrane can be modeled by a parallel combination of an ideal resistor and capacitor, indicating that the membrane efficiently blocks the diffusion of ions.

  8. Robust high temperature oxygen sensor electrodes

    DEFF Research Database (Denmark)

    Lund, Anders

    Platinum is the most widely used material in high temperature oxygen sensor electrodes. However, platinum is expensive and the platinum electrode may, under certain conditions, suffer from poisoning, which is detrimental for an oxygen sensor. The objective of this thesis is to evaluate electrode ......-based electrodes and one porous electrode based on the perovskite-structured strontium and vanadiumdoped lanthanum chromium oxide (LSCV) were investigated. The porous electrodes were applied on yttrium-stabilised zirconium oxide (YSZ) substrates in a collaboration with the company PBI...

  9. Transient current distributions in porous zinc electrodes in KOH electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Liu, M.B.; Yamazaki, Y.; Cook, G.M.; Yao, N.P.

    1981-02-01

    A zero-resistance ammeter circuit with a 10-channel operational amplifier was used to measure the current distribution during a discharge of 10 to 100 mA with simulated zinc porous electrodes in 7.24 M KOH saturated with ZnO. The reaction distribution was found to be highly nonuniform, with 70 to 78% of the charge transfer reaction completed in a depth of 0.01 cm. The high nonuniformity of the initial reaction profile was believed to be due to low conductivity of the electrolyte in the electrode pores. The current distribution changes during passivation of the electrode were experimentally obtained. A mathematical model based upon a macroscope averaging technique was used to predict the time dependence of charge transfer reaction profiles. With mathematical model, current distributions and overpotentials were predicted as a function of time for the segmented zinc electrode discharged at a current of 10 to 100 mA; for these predictions, assumed values of both precipitation rate constants for porous ZnO and diffusion coefficients for hydroxide and zincate ions were used. A gradual decrease in the specific conductivity of the pore electrolyte to 20% of the initial value during discharge yields predictions of current distributions and overpotentials in good agreement with the experimental data. The extent of reduction in the specific conductivity of the pore electrolyte implies a supersaturation of zincate of four times chemical saturation, which was been observed experimentally.At high discharge current (25 to 100 mA), the passivation behavior of the electrode has been simulated. The results of the experiments and mathematical model show that the effective reaction penetration depth is less than 0.02 cm.

  10. A top-down approach for fabricating free-standing bio-carbon supercapacitor electrodes with a hierarchical structure

    OpenAIRE

    Yingzhi Li; Qinghua Zhang; Junxian Zhang; Lei Jin; Xin Zhao; Ting Xu

    2015-01-01

    Biomass has delicate hierarchical structures, which inspired us to develop a cost-effective route to prepare electrode materials with rational nanostructures for use in high-performance storage devices. Here, we demonstrate a novel top-down approach for fabricating bio-carbon materials with stable structures and excellent diffusion pathways; this approach is based on carbonization with controlled chemical activation. The developed free-standing bio-carbon electrode exhibits a high specific ca...

  11. Preparation,Electrochemical Behavior and Electrocatalytic Activity of a Copper Hexacyanoferrate Modified Ceramic Carbon Electrode

    Institute of Scientific and Technical Information of China (English)

    YU,Hao; ZHENG,Jian-Bin

    2007-01-01

    A copper hexacyanoferrate modified ceramic carbon electrode(CuHCF/CCE)had been prepared by two-step sol-gel technique and characterized using electrochemical methods.The resulting modified electrode showed a pair of well-defined surface waves in the potential range of 0.40 to 1.0 V with the formal potential of 0.682 V (vs.SCE)in 0.050 mol·dm-3 HOAc-NaOAc buffer containing 0.30 mol·dm-3 KCI.The charge transfer coefficient (α) and charge transfer rate constant(Ks)for the modified electrode were calculated.The electrocatalytic activity of this modified electrode to hydrazine was also investigated,and chronoamperometry was exploited to conveniently determine the diffusion coefficient(D)of hydrazine in solution and the catalytic rate constant(Kcat).Finally,hydrazine was determined with amperometry using the resulting modified electrode.The calibration plot for hydrazine determination was linear in 3.0×10-6-7.5×10-4 mol·dm-3 with the detection limit of 8.0×10-7 mol·dm-3.This modified electrode had some advantages over the modified film electrodes constructed by the conventional methods,such as renewable surface,good long-term stability,excellent catalytic activity and short response time to hydrazine.

  12. Characterization of azo dyes on Pt and Pt/polyaniline/dispersed Pt electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Molina, J.; Fernandez, J.; Rio, A.I. del; Bonastre, J. [Departamento de Ingenieria Textil y Papelera, EPS de Alcoy, Universitat Politecnica de Valencia, Plaza Ferrandiz y Carbonell s/n, 03801 Alcoy (Spain); Cases, F., E-mail: fjcases@txp.upv.es [Departamento de Ingenieria Textil y Papelera, EPS de Alcoy, Universitat Politecnica de Valencia, Plaza Ferrandiz y Carbonell s/n, 03801 Alcoy (Spain)

    2012-06-15

    The electrochemical characterization of two organic dyes (amaranth and procion orange MX-2R) has been performed on Pt electrodes and Pt electrodes coated with polyaniline and dispersed Pt. Electrodes with different Pt loads have been synthesized and characterized obtaining that a load of 300 {mu}g cm{sup -2} was the optimum one. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) was employed to observe the distribution and morphology of the Pt nanoparticles. The electroactivity of the electrodes has also been characterized by means of scanning electrochemical microscopy (SECM). The chemical characterization of Pt dispersed Pani coated Pt electrodes (Pt-Pani-Pt) was performed by means of X-ray photoelectron spectroscopy (XPS). The electrochemical characterization of the dyes has been performed by means of cyclic voltammetry. Voltammograms have shown that the presence of the dyes diminishes characteristic Pt oxidation and reduction peaks. However, redox processes due to the dyes, appeared in the voltammograms. The different species responsible of these redox processes were generated in the vicinity of the electrode and were not adsorbed on the electrode surface since after stirring, the different redox processes disappeared. Characterization with different scan rates showed that redox processes of both dyes were controlled by diffusion.

  13. Recent advances in metal oxide-based electrode architecture design for electrochemical energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jian; Liu, Jinping; Huang, Xintang [Institute of Nanoscience and Nanotechnology, Department of Physics, Central China Normal University, Wuhan, Hubei (China); Li, Yuanyuan [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan (China); Yuan, Changzhou; Lou, Xiong Wen [School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore (China)

    2012-10-02

    Metal oxide nanostructures are promising electrode materials for lithium-ion batteries and supercapacitors because of their high specific capacity/capacitance, typically 2-3 times higher than that of the carbon/graphite-based materials. However, their cycling stability and rate performance still can not meet the requirements of practical applications. It is therefore urgent to improve their overall device performance, which depends on not only the development of advanced electrode materials but also in a large part ''how to design superior electrode architectures''. In the article, we will review recent advances in strategies for advanced metal oxide-based hybrid nanostructure design, with the focus on the binder-free film/array electrodes. These binder-free electrodes, with the integration of unique merits of each component, can provide larger electrochemically active surface area, faster electron transport and superior ion diffusion, thus leading to substantially improved cycling and rate performance. Several recently emerged concepts of using ordered nanostructure arrays, synergetic core-shell structures, nanostructured current collectors, and flexible paper/textile electrodes will be highlighted, pointing out advantages and challenges where appropriate. Some future electrode design trends and directions are also discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Electrochemical Sensing of Nitric Oxide on Electrochemically Reduced Graphene-Modified Electrode

    Directory of Open Access Journals (Sweden)

    Yu-Li Wang

    2011-01-01

    Full Text Available Graphene-modified electrode was prepared through electrochemically reducing graphene oxide on the surface of a glassy carbon electrode in PBS solution. The as-prepared electrode owns higher stability and stronger catalytic activity towards the oxidation of nitric oxide (NO. At the electrode, an oxidation peak of NO can be observed at about 1.05 V (versus Ag/AgCl, and the electrode reaction of NO is controlled by diffusion process. Under the optimum conditions, the peak currents are dependent linearly on NO concentrations in the range from 7.2×10−7 to 7.84×10−5 M with a limit of detection of 2.0×10−7 M. The response time of the as-prepared electrode to NO is less than 3 s, and the sensitivity is about 299.1 μA/mM, revealing that the electrode can be used as an excellent sensor for the determination of NO. With further modification of Nafion, the determination is free from the interference of nitrite and some other biological substances. This investigation provides an alternate way for the determination of NO.

  15. Recent advances in metal oxide-based electrode architecture design for electrochemical energy storage.

    Science.gov (United States)

    Jiang, Jian; Li, Yuanyuan; Liu, Jinping; Huang, Xintang; Yuan, Changzhou; Lou, Xiong Wen David

    2012-10-02

    Metal oxide nanostructures are promising electrode materials for lithium-ion batteries and supercapacitors because of their high specific capacity/capacitance, typically 2-3 times higher than that of the carbon/graphite-based materials. However, their cycling stability and rate performance still can not meet the requirements of practical applications. It is therefore urgent to improve their overall device performance, which depends on not only the development of advanced electrode materials but also in a large part "how to design superior electrode architectures". In the article, we will review recent advances in strategies for advanced metal oxide-based hybrid nanostructure design, with the focus on the binder-free film/array electrodes. These binder-free electrodes, with the integration of unique merits of each component, can provide larger electrochemically active surface area, faster electron transport and superior ion diffusion, thus leading to substantially improved cycling and rate performance. Several recently emerged concepts of using ordered nanostructure arrays, synergetic core-shell structures, nanostructured current collectors, and flexible paper/textile electrodes will be highlighted, pointing out advantages and challenges where appropriate. Some future electrode design trends and directions are also discussed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Analysis of SOFCs Using Reference Electrodes

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-01

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

  17. Double diffusivity model under stochastic forcing

    Science.gov (United States)

    Chattopadhyay, Amit K.; Aifantis, Elias C.

    2017-05-01

    The "double diffusivity" model was proposed in the late 1970s, and reworked in the early 1980s, as a continuum counterpart to existing discrete models of diffusion corresponding to high diffusivity paths, such as grain boundaries and dislocation lines. It was later rejuvenated in the 1990s to interpret experimental results on diffusion in polycrystalline and nanocrystalline specimens where grain boundaries and triple grain boundary junctions act as high diffusivity paths. Technically, the model pans out as a system of coupled Fick-type diffusion equations to represent "regular" and "high" diffusivity paths with "source terms" accounting for the mass exchange between the two paths. The model remit was extended by analogy to describe flow in porous media with double porosity, as well as to model heat conduction in media with two nonequilibrium local temperature baths, e.g., ion and electron baths. Uncoupling of the two partial differential equations leads to a higher-ordered diffusion equation, solutions of which could be obtained in terms of classical diffusion equation solutions. Similar equations could also be derived within an "internal length" gradient (ILG) mechanics formulation applied to diffusion problems, i.e., by introducing nonlocal effects, together with inertia and viscosity, in a mechanics based formulation of diffusion theory. While being remarkably successful in studies related to various aspects of transport in inhomogeneous media with deterministic microstructures and nanostructures, its implications in the presence of stochasticity have not yet been considered. This issue becomes particularly important in the case of diffusion in nanopolycrystals whose deterministic ILG-based theoretical calculations predict a relaxation time that is only about one-tenth of the actual experimentally verified time scale. This article provides the "missing link" in this estimation by adding a vital element in the ILG structure, that of stochasticity, that takes into

  18. The reaction current distribution in battery electrode materials revealed by XPS-based state-of-charge mapping.

    Science.gov (United States)

    Pearse, Alexander J; Gillette, Eleanor; Lee, Sang Bok; Rubloff, Gary W

    2016-07-28

    Morphologically complex electrochemical systems such as composite or nanostructured lithium ion battery electrodes exhibit spatially inhomogeneous internal current distributions, particularly when driven at high total currents, due to resistances in the electrodes and electrolyte, distributions of diffusion path lengths, and nonlinear current-voltage characteristics. Measuring and controlling these distributions is interesting from both an engineering standpoint, as nonhomogenous currents lead to lower utilization of electrode material, as well as from a fundamental standpoint, as comparisons between theory and experiment are relatively scarce. Here we describe a new approach using a deliberately simple model battery electrode to examine the current distribution in a electrode material limited by poor electronic conductivity. We utilize quantitative spatially resolved X-ray photoelectron spectroscopy to measure the spatial distribution of the state-of-charge of a V2O5 model electrode as a proxy measure for the current distribution on electrodes discharged at varying current densities. We show that the current at the electrode-electrolyte interface falls off with distance from the current collector, and that the current distribution is a strong function of total current. We compare the observed distributions with a simple analytical model which reproduces the dependence of the distribution on total current, but fails to predict the correct length scale. A more complete numerical simulation suggests that dynamic changes in the electronic conductivity of the V2O5 concurrent with lithium insertion may contribute to the differences between theory and experiment. Our observations should help inform design criteria for future electrode architectures.

  19. Electrochemical Glucose Oxidation Using Glassy Carbon Electrodes Modified with Au-Ag Nanoparticles: Influence of Ag Content

    Directory of Open Access Journals (Sweden)

    Nancy Gabriela García-Morales

    2015-01-01

    Full Text Available This paper describes the application of glassy carbon modified electrodes bearing Aux-Agy nanoparticles to catalyze the electrochemical oxidation of glucose. In particular, the paper shows the influence of the Ag content on this oxidation process. A simple method was applied to prepare the nanoparticles, which were characterized by transmission electron microscopy, Ultraviolet-Visible spectroscopy, X-ray diffraction spectroscopy, and cyclic voltammetry. These nanoparticles were used to modify glassy carbon electrodes. The effectiveness of these electrodes for electrochemical glucose oxidation was evaluated. The modified glassy carbon electrodes are highly sensitive to glucose oxidation in alkaline media, which could be attributed to the presence of Aux-Agy nanoparticles on the electrode surface. The voltammetric results suggest that the glucose oxidation speed is controlled by the glucose diffusion to the electrode surface. These results also show that the catalytic activity of the electrodes depends on the Ag content of the nanoparticles. Best results were obtained for the Au80-Ag20 nanoparticles modified electrode. This electrode could be used for Gluconic acid (GA production.

  20. Performance Measurement of AMTEC Electrode

    Institute of Scientific and Technical Information of China (English)

    MA; Jun-ping; HE; Hu; LI; Si-jie; TANG; Xian; LUO; Zhi-fu

    2015-01-01

    Alkali metal thermal to electric converter(AMTEC)is a direct energy conversion device capable of near-Carnot efficiencies,and has demonstrated the performance of high power density,high current low voltage.Electrode is a key component of achieving high efficiency in an AMTEC device.A RhW alloy target was used for deposition

  1. Thermal aging stability of infiltrated solid oxide fuel cell electrode microstructures: A three-dimensional kinetic Monte Carlo simulation

    Science.gov (United States)

    Zhang, Yanxiang; Ni, Meng; Yan, Mufu; Chen, Fanglin

    2015-12-01

    Nanostructured electrodes are widely used for low temperature solid oxide fuel cells, due to their remarkably high activity. However, the industrial applications of the infiltrated electrodes are hindered by the durability issues, such as the microstructure stability against thermal aging. Few strategies are available to overcome this challenge due to the limited knowledge about the coarsening kinetics of the infiltrated electrodes and how the potentially important factors affect the stability. In this work, the generic thermal aging kinetics of the three-dimensional microstructures of the infiltrate electrodes is investigated by a kinetic Monte Carlo simulation model considering surface diffusion mechanism. Effects of temperature, infiltration loading, wettability, and electrode configuration are studied and the key geometric parameters are calculated such as the infiltrate particle size, the total and percolated quantities of three-phase boundary length and infiltrate surface area, and the tortuosity factor of infiltrate network. Through parametric study, several strategies to improve the thermal aging stability are proposed.

  2. 21 CFR 870.2360 - Electrocardiograph electrode.

    Science.gov (United States)

    2010-04-01

    ... electrode. (a) Identification. An electrocardiograph electrode is the electrical conductor which is applied to the surface of the body to transmit the electrical signal at the body surface to a processor...

  3. A method for making a hydrogen electrode

    Energy Technology Data Exchange (ETDEWEB)

    Ikeyama, M.; Ivaki, T.; Yanagikhara, N.

    1983-09-08

    A metallic grid is pressed to the surface of a foam metallic plate which contains powders of a compound which adsorb H2. The electrode is processed at the powder caking temperature. The electrode has a long service life.

  4. Impurity features in Ni-YSZ-H2-H2O electrodes

    DEFF Research Database (Denmark)

    Utz, A.; Hansen, Karin Vels; Norrman, Kion;

    2011-01-01

    -of-flight secondary ion mass spectrometry). This analysis yields comprehensive information on composition and lateral distribution of impurity species as well as the size of impurity features. Small impurity striations are found at the triple phase boundary (TPB) as well as on the former electrode......–electrolyte interface and the impurity features were found to be influenced by the electrode configuration and the initial behavior of the Ni electrode during thermal exposure (creep or shrinkage).Furthermore, the electrochemical performance (the line specific resistance LSR) was compared to data reported for Ni point...... anodes. Good agreement was obtained for data with comparable impurity features.Additionally, an order of magnitude estimation of the effect of SiO2 content on surface coverage with an impurity film is performed for different electrode designs (point, patterned and cermet anode) and shows different...

  5. Utility of CT-compatible EEG electrodes in critically ill children

    Energy Technology Data Exchange (ETDEWEB)

    Abend, Nicholas S. [Perelman School of Medicine at the University of Pennsylvania, Departments of Neurology and Pediatrics, The Children' s Hospital of Philadelphia, Philadelphia, PA (United States); CHOP Neurology, Philadelphia, PA (United States); Dlugos, Dennis J. [Perelman School of Medicine at the University of Pennsylvania, Departments of Neurology and Pediatrics, The Children' s Hospital of Philadelphia, Philadelphia, PA (United States); Zhu, Xiaowei; Schwartz, Erin S. [Perelman School of Medicine at the University of Pennsylvania, Department of Radiology, The Children' s Hospital of Philadelphia, Philadelphia, PA (United States)

    2015-05-01

    Electroencephalographic monitoring is being used with increasing frequency in critically ill children who may require frequent and sometimes urgent brain CT scans. Standard metallic disk EEG electrodes commonly produce substantial imaging artifact, and they must be removed and later reapplied when CT scans are indicated. To determine whether conductive plastic electrodes caused artifact that limited CT interpretation. We describe a retrospective cohort of 13 consecutive critically ill children who underwent 17 CT scans with conductive plastic electrodes during 1 year. CT images were evaluated by a pediatric neuroradiologist for artifact presence, type and severity. All CT scans had excellent quality images without artifact that impaired CT interpretation except for one scan in which improper wire placement resulted in artifact. Conductive plastic electrodes do not cause artifact limiting CT scan interpretation and may be used in critically ill children to permit concurrent electroencephalographic monitoring and CT imaging. (orig.)

  6. The electro-oxidative activity of cysteine on the Au electrode as evidenced by surface enhanced Raman scattering

    Science.gov (United States)

    Liu, Zhaojun; Wu, Guozhen

    2006-05-01

    It is demonstrated from the surface-enhanced Raman scattering that cysteine is adsorbed on the Au electrode via its carboxylate moiety. The mechanism is mainly via the charge transfer involving the π electron-rich carboxylate moiety. The adsorption of cysteine is weak that its diffusion on the Au surface is possible. The collision of two cysteine molecules may lead to the electro-oxidative formation of cystine in an irreversible way due to that the disulfide bond is not in the close vicinity of the electrode and its rupture is hampered. The physical difference as compared to its adsorption on the Ag electrode is stressed.

  7. Direct electrical communication between chemically modified enzymes and metal electrodes. 1. Electron transfer from glucose oxidase to metal electrodes via electron relays, bound covalently to the enzyme

    Energy Technology Data Exchange (ETDEWEB)

    Degani, Y.; Heller, A.

    1987-03-12

    Glucose-reduced glucose oxidase does not directly transfer electrons to conventional electrodes because the distance between its redox centers and the electrode surface exceeds, even on closest approach, the distance across which electrons are transferred at sufficient rates. Therefore, electrical communication between the redox centers of this enzyme and electrodes required either the presence, and diffusion to and from the enzyme's redox center, of O/sub 2/ and H/sub 2/O/sub 2/, or the presence of members of a redox couple, or the use of special electrodes like TTF/TCNQ. They show here that direct electrical communication between the redox center of a large enzyme molecule and a simple metal electrode can be established through chemical modification of the enzyme. When a sufficient number of electron-relaying centers are attached through covalent bonding to the protein of glucose oxidase, electrons are transferred from the enzyme's redox centers to relays that are closer to the periphery of the enzyme. Because some of the relays are located sufficiently close to the enzyme's surface, electrons are transferred at practical rates to the electrode. As a result, a glucose-concentration-dependent current flows in an electrochemical cell made with conventional electrodes when the electrolytic solution contains the relay-modified enzyme. Such a current does not flow when the solution contains the natural enzyme. Specifically, electrical communication is established between the FAD/FADH/sub 2/ centers of glucose oxidase and gold, platinum, or carbon electrodes through the covalent bonding of an average of 12 molecules of ferrocenecarboxylic acid per glucose oxidase molecule.

  8. A method for the manufacture of electrodes

    OpenAIRE

    Kervenic, Y.V.; van der Zant, S.J.; Morpurgo, A.; Gurevich, L.; Kouwenhoven, L. P.

    2003-01-01

    A method of reducing the distance between electrodes, comprising the growth of electrodes by means of electrodeposition in a solution, wherein during the process of growth the conductance over the electrodes is measured and the method is terminated when the conductance has reached a predetermined value. The method according to the invention is characterised in that measuring arrangement for measuring the conductance is suitable for measuring an electric current between the electrodes when the...

  9. Biological, mechanical, and technological considerations affecting the longevity of intracortical electrode recordings.

    Science.gov (United States)

    Harris, James P; Tyler, Dustin J

    2013-01-01

    Intracortical electrodes are important tools, with applications ranging from fundamental laboratory studies to potential solutions to intractable clinical applications. However, the longevity and reliability of the interfaces remain their major limitation to the wider implementation and adoption of this technology, especially in broader translational work. Accordingly, this review summarizes the most significant biological and technical factors influencing the long-term performance of intracortical electrodes. In a laboratory setting, intracortical electrodes have been used to study the normal and abnormal function of the brain. This improved understanding has led to valuable insights regarding many neurological conditions. Likewise, clinical applications of intracortical brain-machine interfaces offer the ability to improve the quality of life of many patients afflicted with high-level paralysis from spinal cord injury, brain stem stroke, amyotrophic lateral sclerosis, or other conditions. It is widely hypothesized that the tissue response to the electrodes, including inflammation, limits their longevity. Many studies have examined and modified the tissue response to intracortical electrodes to improve future intracortical electrode technologies. Overall, the relationship between biological, mechanical, and technological considerations are crucial for the fidelity of chronic electrode recordings and represent a presently active area of investigation in the field of neural engineering.

  10. Isotope Fractionation by Diffusion in Liquids (Final Technical Report)

    Energy Technology Data Exchange (ETDEWEB)

    Richter, Frank [Univ. of Chicago, IL (United States)

    2016-11-09

    The overall objective of the DOE-funded research by grant DE-FG02-01ER15254 was document and quantify kinetic isotope fractionations during chemical and thermal (i.e., Soret) diffusion in liquids (silicate melts and water) and in the later years to include alloys and major minerals such as olivine and pyroxene. The research involved both laboratory experiments and applications to natural settings. The key idea is that major element zoning on natural geologic materials is common and can arise for either changes in melt composition during cooling and crystallization or from diffusion. The isotope effects associated with diffusion that we have documented are the key for determining whether or not the zoning observed in a natural system was the result of diffusion. Only in those cases were the zoning is demonstrably due to diffusion can use independently measured rates of diffusion to constrain the thermal evolution of the system.

  11. Bass-SIR model for diffusion of new products

    CERN Document Server

    Fibich, Gadi

    2016-01-01

    We consider the diffusion of new products in social networks, where consumers who adopt the product can later "recover" and stop influencing others to adopt the product. We show that the diffusion is not described by the SIR model, but rather by a novel model, the Bass-SIR model, which combines the Bass model for diffusion of new products with the SIR model for epidemics. The phase transition of consumers from non-adopters to adopters is described by a non-standard Kolmogorov-Johnson-Mehl-Avrami model, in which clusters growth is limited by adopters' recovery. Therefore, diffusion in the Bass-SIR model only depends on the local structure of the social network, but not on the average distance between consumers. Consequently, unlike the SIR model, a small-worlds structure has a negligible effect on the diffusion. Surprisingly, diffusion on scale-free networks is nearly identical to that on Cartesian ones.

  12. A method for the manufacture of electrodes

    NARCIS (Netherlands)

    Kervenic, Y.V.; Van der Zant, S.J.; Morpurgo , A.; Gurevich , L.; Kouwenhoven, L.P.

    2003-01-01

    A method of reducing the distance between electrodes, comprising the growth of electrodes by means of electrodeposition in a solution, wherein during the process of growth the conductance over the electrodes is measured and the method is terminated when the conductance has reached a predetermined

  13. Membrane electrode assembly for a fuel cell

    Science.gov (United States)

    Prakash, Surya (Inventor); Narayanan, Sekharipuram R. (Inventor); Atti, Anthony (Inventor); Olah, George (Inventor); Smart, Marshall C. (Inventor)

    2006-01-01

    A catalyst ink for a fuel cell including a catalytic material and poly(vinylidene fluoride). The ink may be applied to a substrate to form an electrode, or bonded with other electrode layers to form a membrane electrode assembly (MEA).

  14. An ionization chamber with magnetic levitated electrodes

    CERN Document Server

    Kawaguchi, T

    1999-01-01

    A new type of ionization chamber which has magnetically levitated electrodes has been developed. The electrodes are supplied voltages for the repelling of ions by a battery which is also levitated with the electrodes. The characteristics of this ionization chamber are investigated in this paper.

  15. 21 CFR 890.1175 - Electrode cable.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Electrode cable. 890.1175 Section 890.1175 Food... DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Diagnostic Devices § 890.1175 Electrode cable. (a) Identification. An electrode cable is a device composed of strands of insulated electrical conductors...

  16. Metric diffusion along foliations

    CERN Document Server

    Walczak, Szymon M

    2017-01-01

    Up-to-date research in metric diffusion along compact foliations is presented in this book. Beginning with fundamentals from the optimal transportation theory and the theory of foliations; this book moves on to cover Wasserstein distance, Kantorovich Duality Theorem, and the metrization of the weak topology by the Wasserstein distance. Metric diffusion is defined, the topology of the metric space is studied and the limits of diffused metrics along compact foliations are discussed. Essentials on foliations, holonomy, heat diffusion, and compact foliations are detailed and vital technical lemmas are proved to aide understanding. Graduate students and researchers in geometry, topology and dynamics of foliations and laminations will find this supplement useful as it presents facts about the metric diffusion along non-compact foliation and provides a full description of the limit for metrics diffused along foliation with at least one compact leaf on the two dimensions.

  17. Measurement of noise and impedance of dry and wet textile electrodes, and textile electrodes with hydrogel.

    Science.gov (United States)

    Puurtinen, Merja M; Komulainen, Satu M; Kauppinen, Pasi K; Malmivuo, Jaakko A V; Hyttinen, Jari A K

    2006-01-01

    Textile sensors, when embedded into clothing, can provide new ways of monitoring physiological signals, and improve the usability and comfort of such monitoring systems in the areas of medical, occupational health and sports. However, good electrical and mechanical contact between the electrode and the skin is very important, as it often determines the quality of the signal. This paper introduces a study where the properties of dry textile electrodes, textile electrodes moistened with water, and textile electrodes covered with hydrogel were studied with five different electrode sizes. The aim was to study how the electrode size and preparation of the electrode (dry electrode/wet electrode/electrode covered with hydrogel membrane) affect the measurement noise, and the skin-electrode impedance. The measurement noise and skin-electrode impedance were determined from surface biopotential measurements. These preliminary results indicate that noise level increases as the electrode size decreases. The noise level is high in dry textile electrodes, as expected. Yet, the noise level of wet textile electrodes is quite low and similar to that of textile electrodes covered with hydrogel. Hydrogel does not seem to improve noise properties, however it may have effects on movement artifacts. Thus, it is feasible to use textile embedded sensors in physiological monitoring applications when moistening or hydrogel is applied.

  18. Reducing Insertion Sites of Penetrating Multipolar Shaft Electrodes by Double Side Electrode Arrangement

    Science.gov (United States)

    2007-11-02

    Abstract-Micromachined devices with substrate-integrated elec- trodes are the key component in implantable microdevices for recording neuronal ...INSERTION SITES OF PENETRATING MULTIPOLAR SHAFT ELECTRODES BY DOUBLE SIDE ELECTRODE ARRANGEMENT T.Stieglitz1, P. Heiduschka2, M. Schuettler1, M. Gross1...and Subtitle Reducing Insertion Sites of Penetrating Multipolar Shaft Electrodes by Double Side Electrode Arrangement Contract Number Grant Number

  19. CATALYTIC AND ELECTROCATALYTIC ACTIVITY OF Pt-Ru/C ELECTRODE FOR HYDROGEN OXIDATION IN ALKALINE

    Directory of Open Access Journals (Sweden)

    D. LABOU

    2008-07-01

    Full Text Available The kinetics of the oxidation of H2 on PtRu/C gas-diffusion electrode was studied by interfacing the electrode with aqueous electrolytes at different pH values. The conducting electrolytes were KOH and HClO4 aqueous solutions with different concentrations. It is shown that the nature of the aqueous electrolyte plays the role of an active catalyst support for the PtRu/C electrode which drastically affects its catalytic properties. During the aforementioned interaction, termed electrochemical metal support interaction (EMSI, the electrochemical potential of the electrons at the catalyst Fermi level is equalised with the electrochemical potential of the solvated electron in the aqueous electrolyte. The electrochemical experiments carried out at various pH values showed that the electrochemical promotion catalysis (EPOC is more intense when the catalyst-electrode is interfaced with electrolytes with high pH values where the OH– ionic conduction prevails. It was concluded that similar to the solid state electrochemical systems EPOC proceeds through the formation of a polar adsorbed promoting layer of , electrochemically supplied by the OH- species, at the three phase boundaries of the gas exposed gas diffusion catalyst-electrode surface.

  20. Electrochemical degradation of pyridine by Ti/SnO2-Sb tubular porous electrode.

    Science.gov (United States)

    Li, Duo; Tang, Jingyan; Zhou, Xiezhen; Li, Jiansheng; Sun, Xiuyun; Shen, Jinyou; Wang, Lianjun; Han, Weiqing

    2016-04-01

    Diffusion in electrochemistry is a critical issue for water purification. Electrocatalytic reactor system in improving water quality is a useful way to induce convection to enhance diffusion. This study focuses on the preparation and the characterization of Ti/SnO2-Sb tubular porous electrode for degrading pyridine wastewater. The electrode as an anode in reactor system is prepared by coating SnO2-Sb as an electro-catalyst via Pechini method on the tubular porous Ti. Scanning Electron Microscopy, Energy Dispersive Spectrum, X-ray Diffraction and Pore Distribution are employed to evaluate the structure and morphology of the electrodes coatings, and Linear Sweep Voltammetry and Cyclic Voltammetry are used to illustrate the electrochemical properties of the electrodes coatings. Furthermore, the electrochemical oxidation performance of Ti/SnO2-Sb tubular porous electrode is characterized by degrading pyridine wastewater. The effects of flow and static pattern, initial pyridine concentration, supporting electrolyte concentration, current density and pH on the performance of the reactor were investigated in the electrocatalytic reactor system. The results indicated that the removal ratio of pyridine reaches maximum which is 98% under the optimal operation conditions, that are 100 mg L(-1) initial pyridine concentration, 10 g L(-1) supporting electrolyte concentration, 30 mA cm(-2) current density and pH 3. Transition state calculation based on the density function theory was combined with High Performance Liquid Chromatography, Gas Chromatography and Ionic Chromatography results to describe the pathway of pyridine degradation.

  1. Heat-resistant thin film photoelectric converter with diffusion blocking layer

    Energy Technology Data Exchange (ETDEWEB)

    Takada, Jun; Yamaguchi, Minori; Tawada, Yoshihisa.

    1990-06-26

    The photoelectric converter of this invention comprises a semiconductor, an electrode, and a diffusion-blocking layer provided between the semiconductor and at least one electrode. An object of this invention is to provide a thin film photoelectric converter which has good heat resistance, in order to avoid the reduction in quality owing to the diffusion of metal or metallic compound from the electrode to the semiconductor layer, on the condition that the ohmic loss in the backing electrode and the reflection loss of light at the backing electrode are not increased. The component of the diffusion-blocking layer is selected from among such materials as metal silicides, silicide-forming metals, and metals from Groups IVA and VA of the periodic table. A preferable thickness of the diffusion-blocking layer is 5 to 500 angstroms. The semiconductor can be of the p-i-n, p-n, or Schottky type, and can be 0.02 to 100 {mu}m thick. For a semiconductor which comes into contact with the diffusion-blocking layer, n-type is preferable because it offers great improvements in the characteristics of the photoelectric converter. The electrode on the light-incident side is transparent and made of a metallic compound such as In{sub 2}O{sub 3}, SnO{sub 2}, Cd{sub x}SnO{sub y} (x=0.5 to 2, y=2 to 4) or the like. The backing electrode material is selected to have a suitable conductivity and reflectivity; such materials include Ag, Au, Al or Cu. The invention also discloses a method of preparing the thick film photoelectric converter, and examples are provided to illustrate the preparation of various embodiments of the invention. 2 figs., 1 tab.

  2. Pineocytoma with diffuse dissemination to the leptomeninges

    Directory of Open Access Journals (Sweden)

    Michael Selch

    2011-10-01

    Full Text Available Pineal parenchymal tumors are rare. Of the three types of pineal parenchymal tumors, pineocytomas are the least aggressive and are not known to diffusely disseminate. In this paper, we report the successful treatment of a case of pineocytoma with diffuse leptomeningeal relapse following initial stereotactic radiotherapy. A 39-year-old female presented with headaches, balance impairment, urinary incontinence, and blunted affect. A pineal mass was discovered on magnetic resonance imaging (MRI. A diagnosis of pineocytoma was established with an endoscopic pineal gland biopsy, and the patient received stereotactic radiotherapy. Ten years later, she developed diffuse leptomeningeal dissemination. The patient was then successfully treated with craniospinal radiation therapy. Leptomeningeal spread may develop as late as 10 years after initial presentation of pineocytoma. Our case demonstrates the importance of long-term follow-up of patients with pineal parenchymal tumors following radiation therapy, and the efficacy of craniospinal radiation in the treatment of leptomeningeal dissemination.

  3. ENOBIO dry electrophysiology electrode; first human trial plus wireless electrode system.

    Science.gov (United States)

    Ruffini, Giulio; Dunne, Stephen; Farres, Esteve; Cester, Ivan; Watts, Paul C P; Silva, S P; Grau, Carles; Fuentemilla, Lluis; Marco-Pallares, Josep; Vandecasteele, Bjorn

    2007-01-01

    This paper presents the results of the first human trials with the ENOBIO electrophysiology electrode prototype plus the initial results of a new wireless prototype with flexible electrodes based on the same platform. The results indicate that a dry active electrode that employs a CNT array as the electrode interface can perform on a par with traditional "wet" electrodes for the recording of EEG, ECG, EOG and EMG. We also demonstrate a new platform combining wireless technology plus flexible electrodes for improved comfort for applications that take advantage of the dry electrode concept.

  4. Active matter in lateral parabolic confinement: From subdiffusion to superdiffusion

    Science.gov (United States)

    Ribeiro, H. E.; Potiguar, F. Q.

    2016-11-01

    In this work we studied the diffusive behavior of active brownian particles under lateral parabolic confinement. The results showed that we go from subdiffusion to ballistic motion as we vary the angular noise strength and confinement intensity. We argued that the subdiffusion regimes appear as consequence of the restricted space available for diffusion (achieved either through large confinement and/or large noise); we saw that when there are large confinement and noise intensity, a similar configuration to single file diffusion appears; on the other hand, normal and superdiffusive regimes may occur due to low noise (longer persistent motion), either through exploring a wider region around the potential minimum in the transverse direction (low confinement), or by forming independent clusters (high confinement).

  5. Inpainting using airy diffusion

    Science.gov (United States)

    Lorduy Hernandez, Sara

    2015-09-01

    One inpainting procedure based on Airy diffusion is proposed, implemented via Maple and applied to some digital images. Airy diffusion is a partial differential equation with spatial derivatives of third order in contrast with the usual diffusion with spatial derivatives of second order. Airy diffusion generates the Airy semigroup in terms of the Airy functions which can be rewritten in terms of Bessel functions. The Airy diffusion can be used to smooth an image with the corresponding noise elimination via convolution. Also the Airy diffusion can be used to erase objects from an image. We build an algorithm using the Maple package ImageTools and such algorithm is tested using some images. Our results using Airy diffusion are compared with the similar results using standard diffusion. We observe that Airy diffusion generates powerful filters for image processing which could be incorporated in the usual packages for image processing such as ImageJ and Photoshop. Also is interesting to consider the possibility to incorporate the Airy filters as applications for smartphones and smart-glasses.

  6. The voltammetric responses of nanometer-sized electrodes in weakly supported electrolyte: A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yuwen; Zhang Qianfan [Hubei Electrochemical Power Sources Key Laboratory, Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072 (China); Chen Shengli, E-mail: slchen@whu.edu.c [Hubei Electrochemical Power Sources Key Laboratory, Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072 (China)

    2010-11-30

    The effect of the supporting electrolyte concentration on the interfacial profiles and voltammetric responses of nanometer-sized disk electrodes have been investigated theoretically by combining the Poisson-Nernst-Planck (PNP) theory and Butler-Volmer (BV) equation. The PNP-theory is used to treat the nonlinear couplings of electric field, concentration field and dielectric field at electrochemical interface without the electroneutrality assumption that has been long adopted in various voltammetric theories for macro/microelectrodes. The BV equation is modified by using the Frumkin correction to account for the effect of the diffuse double layer potential on interfacial electron-transfer (ET) rate and by including a distance-dependent ET probability in the expression of rate constant to describe the radial heterogeneity of the ET rate constant at nanometer-sized disk electrodes. The computed voltammetric responses for disk electrodes larger than 200 nm in radii in the absence of the excess of the supporting electrolyte using the present theoretical scheme show reasonable agreements with the predications of the conventional microelectrode voltammetric theory which uses the combined Nernst-Planck equation and electroneutrality equation to describe the mixed electromigration-diffusion mass transport without including the possible effects of the diffuse double layer (Amatore et al. ). For electrodes smaller than 200 nm, however, the voltammetric responses predicated by the present theory exhibit significant deviation from the microelectrode theory. It is shown that the deviations are mainly resulted from the overlap between the diffuse double layer and the concentration depletion layer (CDL) at nanoscale electrochemical interfaces in weakly supported media, which will result in the invalidation of the electroneutrality condition in CDL, and from the radial inhomogeneity of ET probability at nanometer-sized disk electrodes.

  7. What causes amyotrophic lateral sclerosis?

    Science.gov (United States)

    Martin, Sarah; Al Khleifat, Ahmad; Al-Chalabi, Ammar

    2017-01-01

    Amyotrophic lateral sclerosis is a neurodegenerative disease predominantly affecting upper and lower motor neurons, resulting in progressive paralysis and death from respiratory failure within 2 to 3 years. The peak age of onset is 55 to 70 years, with a male predominance. The causes of amyotrophic lateral sclerosis are only partly known, but they include some environmental risk factors as well as several genes that have been identified as harbouring disease-associated variation. Here we review the nature, epidemiology, genetic associations, and environmental exposures associated with amyotrophic lateral sclerosis. PMID:28408982

  8. What causes amyotrophic lateral sclerosis?

    Science.gov (United States)

    Martin, Sarah; Al Khleifat, Ahmad; Al-Chalabi, Ammar

    2017-01-01

    Amyotrophic lateral sclerosis is a neurodegenerative disease predominantly affecting upper and lower motor neurons, resulting in progressive paralysis and death from respiratory failure within 2 to 3 years. The peak age of onset is 55 to 70 years, with a male predominance. The causes of amyotrophic lateral sclerosis are only partly known, but they include some environmental risk factors as well as several genes that have been identified as harbouring disease-associated variation. Here we review the nature, epidemiology, genetic associations, and environmental exposures associated with amyotrophic lateral sclerosis.

  9. Understanding electrode materials of rechargeable lithium batteries via DFT calculations

    Institute of Scientific and Technical Information of China (English)

    Tianran Zhang; Daixin Li; Zhanliang Tao; Jun Chenn

    2013-01-01

    Rechargeable lithium batteries have achieved a rapid advancement and commercialization in the past decade owing to their high capacity and high power density. Different functional materials have been put forward progressively, and each possesses distinguishing structural features and electrochemical properties. In virtue of density functional theory (DFT) calculations, we can start from a specific structure to get a deep comprehension and accurate prediction of material properties and reaction mechanisms. In this paper, we review the main progresses obtained by DFT calculations in the electrode materials of rechargeable lithium batteries, aiming at a better understanding of the common electrode materials and gaining insights into the battery performance. The applications of DFT calculations involve in the following points of crystal structure modeling and stability investigations of delithiated and lithiated phases, average lithium intercalation voltage, prediction of charge distributions and band structures, and kinetic studies of lithium ion diffusion processes, which can provide atomic understanding of the capacity, reaction mechanism, rate capacity, and cycling ability. The results obtained from DFT are valuable to reveal the relationship between the structure and the properties, promoting the design of new electrode materials.

  10. Formic Acid Electrooxidation by a Platinum Nanotubule Array Electrode

    Directory of Open Access Journals (Sweden)

    Eric Broaddus

    2013-01-01

    Full Text Available One-dimensional metallic nanostructures such as nanowires, rods, and tubes have drawn much attention for electrocatalytic applications due to potential advantages that include fewer diffusion impeding interfaces with polymeric binders, more facile pathways for electron transfer, and more effective exposure of active surface sites. 1D nanostructured electrodes have been fabricated using a variety of methods, typically showing improved current response which has been attributed to improved CO tolerance, enhanced surface activity, and/or improved transport characteristics. A template wetting approach was used to fabricate an array of platinum nanotubules which were examined electrochemically with regard to the electrooxidation of formic acid. Arrays of 100 and 200 nm nanotubules were compared to a traditional platinum black catalyst, all of which were found to have similar surface areas. Peak formic acid oxidation current was observed to be highest for the 100 nm nanotubule array, followed by the 200 nm array and the Pt black; however, CO tolerance of all electrodes was similar, as were the onset potentials of the oxidation and reduction peaks. The higher current response was attributed to enhanced mass transfer in the nanotubule electrodes, likely due to a combination of both the more open nanostructure as well as the lack of a polymeric binder in the catalyst layer.

  11. Spray deposition of Nafion membranes: Electrode-supported fuel cells

    Science.gov (United States)

    Bayer, Thomas; Pham, Hung Cuong; Sasaki, Kazunari; Lyth, Stephen Matthew

    2016-09-01

    Fuel cells are a key technology for the successful transition towards a hydrogen society. In order to accelerate fuel cell commercialization, improvements in performance are required. Generally, polymer electrolyte membrane fuel cells (PEFCs) are membrane-supported; the electrocatalyst layer is sprayed onto both sides of the membrane, and sandwiched between carbon-based gas diffusion layers (GDLs). In this work we redesign the membrane electrode assembly (MEA) and fabricate an electrode-supported PEFC. First the electrocatalyst layer is sprayed onto the GDL, and then Nafion dispersion is sprayed over the top of this to form a thin membrane. This method has the advantage of simplifying the fabrication process, allowing the fabrication of extremely thin electrolyte layers (down to ∼10 μm in this case), and reducing the amount of ionomer required in the cell. Electrode-supported PEFCs operate at significantly increased power density compared to conventional membrane-supported PEFCs, with a maximum of 581 mW/cm2 at 80 °C (atmospheric pressure, air at the cathode). Impedance spectroscopy confirmed that the origin of the improved performance was an 80% reduction in the membrane resistance due the thinner Nafion layer. This novel fabrication method is a step towards cheaper, thinner, fully printable PEFCs with high power density and efficiency.

  12. ELECTROANALYTICAL APPLICATIONS OF CARBOXYL-MODIFIED CARBON NANOTUBE FILM ELECTRODES

    Institute of Scientific and Technical Information of China (English)

    C.G. Hu; W.L. Wang; K.J. Liao; W. Zhu

    2003-01-01

    The electrochemical behavior of a carboxyl-modified carbon nanotube films was investigated to explore its possibility in electroanalytical applicaton. Cyclic voltammetry of quinone was conducted in 1mol/L Na2SO4, which showed a stable, quasi-reversible voltammetric response for quinone / hydroquinone, and the anodic and the cathodic peak potentials were 0.657V and -0.029V (vs. SCE) at a scan rate of 0.1V.s-1, respectively. Both anodic and cathodic peak currents depended linearly on the square root of the scan rate over the range of 0.01-0. 5 V.s-1, which suggested that the process of the electrode reactions was diffusion-controlled. Carboxyl-modified carbon nanotube electrodes made it possible to determine low level of dopamine selectively in the presence of a large excess of ascorbic acid in acidic media using derivative voltammetry.The results obtained were discussed in details. This work demonstrates the potential of carboxyl-modified carbon nanotube electrodes for electroanalytical applications.

  13. Photovoltachromic device with a micropatterned bifunctional counter electrode.

    Science.gov (United States)

    Cannavale, Alessandro; Manca, Michele; De Marco, Luisa; Grisorio, Roberto; Carallo, Sonia; Suranna, Gian Paolo; Gigli, Giuseppe

    2014-02-26

    A photovoltachromic window can potentially act as a smart glass skin which generates electric energy as a common dye-sensitized solar cell and, at the same time, control the incoming energy flux by reacting to even small modifications in the solar radiation intensity. We report here the successful implementation of a novel architecture of a photovoltachromic cell based on an engineered bifunctional counter electrode consisting of two physically separated platinum and tungsten oxide regions, which are arranged to form complementary comb-like patterns. Solar light is partially harvested by a dye-sensitized photoelectrode made on the front glass of the cell which fully overlaps a bifunctional counter electrode made on the back glass. When the cell is illuminated, the photovoltage drives electrons into the electrochromic stripes through the photoelectrochromic circuit and promotes the Li(+) diffusion towards the WO3 film, which thus turns into its colored state: a photocoloration efficiency of 17 cm(2) min(-1) W(-1) at a wavelength of 650 nm under 1.0 sun was reported along with fast response (coloration time photovoltaic functionality was also retained due to the copresence of the independently switchable micropatterned platinum electrode.

  14. Reaction-diffusion basis of retroviral infectivity

    Science.gov (United States)

    Sadiq, S. Kashif

    2016-11-01

    Retrovirus particle (virion) infectivity requires diffusion and clustering of multiple transmembrane envelope proteins (Env3) on the virion exterior, yet is triggered by protease-dependent degradation of a partially occluding, membrane-bound Gag polyprotein lattice on the virion interior. The physical mechanism underlying such coupling is unclear and only indirectly accessible via experiment. Modelling stands to provide insight but the required spatio-temporal range far exceeds current accessibility by all-atom or even coarse-grained molecular dynamics simulations. Nor do such approaches account for chemical reactions, while conversely, reaction kinetics approaches handle neither diffusion nor clustering. Here, a recently developed multiscale approach is considered that applies an ultra-coarse-graining scheme to treat entire proteins at near-single particle resolution, but which also couples chemical reactions with diffusion and interactions. A model is developed of Env3 molecules embedded in a truncated Gag lattice composed of membrane-bound matrix proteins linked to capsid subunits, with freely diffusing protease molecules. Simulations suggest that in the presence of Gag but in the absence of lateral lattice-forming interactions, Env3 diffuses comparably to Gag-absent Env3. Initial immobility of Env3 is conferred through lateral caging by matrix trimers vertically coupled to the underlying hexameric capsid layer. Gag cleavage by protease vertically decouples the matrix and capsid layers, induces both matrix and Env3 diffusion, and permits Env3 clustering. Spreading across the entire membrane surface reduces crowding, in turn, enhancing the effect and promoting infectivity. This article is part of the themed issue 'Multiscale modelling at the physics-chemistry-biology interface'.

  15. Powder processing of hybrid titanium neural electrodes

    Science.gov (United States)

    Lopez, Jose Luis, Jr.

    A preliminary investigation into the powder production of a novel hybrid titanium neural electrode for EEG is presented. The rheological behavior of titanium powder suspensions using sodium alginate as a dispersant are examined for optimal slip casting conditions. Electrodes were slip cast and sintered at 950°C for 1 hr, 1000°C for 1, 3, and 6 hrs, and 1050°C for 1 hr. Residual porosities from sintering are characterized using Archimedes' technique and image analysis. The pore network is gel impregnated by submerging the electrodes in electrically conductive gel and placing them in a chamber under vacuum. Gel evaporation of the impregnated electrodes is examined. Electrodes are characterized in the dry and gelled states using impedance spectrometry and compared to a standard silver- silver chloride electrode. Power spectral densities for the sensors in the dry and gelled state are also compared. Residual porosities for the sintered specimens were between 50.59% and 44.81%. Gel evaporation tests show most of the impregnated gel evaporating within 20 min of exposure to atmospheric conditions with prolonged evaporation times for electrodes with higher impregnated gel mass. Impedance measurements of the produced electrodes indicate the low impedance of the hybrid electrodes are due to the increased contact area of the porous electrode. Power spectral densities of the titanium electrode behave similar to a standard silver-silver chloride electrode. Tests suggest the powder processed hybrid titanium electrode's performance is better than current dry contact electrodes and comparable to standard gelled silver-silver chloride electrodes.

  16. Scaling Relations for Intercalation Induced Damage in Electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Chien-Fan; Barai, Pallab; Smith, Kandler; Mukherjee, Partha P.

    2016-06-01

    Mechanical degradation, owing to intercalation induced stress and microcrack formation, is a key contributor to the electrode performance decay in lithium-ion batteries (LIBs). The stress generation and formation of microcracks are caused by the solid state diffusion of lithium in the active particles. In this work, scaling relations are constructed for diffusion induced damage in intercalation electrodes based on an extensive set of numerical experiments with a particle-level description of microcrack formation under disparate operating and cycling conditions, such as temperature, particle size, C-rate, and drive cycle. The microcrack formation and evolution in active particles is simulated based on a stochastic methodology. A reduced order scaling law is constructed based on an extensive set of data from the numerical experiments. The scaling relations include combinatorial constructs of concentration gradient, cumulative strain energy, and microcrack formation. The reduced order relations are further employed to study the influence of mechanical degradation on cell performance and validated against the high order model for the case of damage evolution during variable current vehicle drive cycle profiles.

  17. Direct measurement of time dependent diffusion for Ag and Au under ambient conditions

    Science.gov (United States)

    Yoo, Pil Sun; Jo, Han Yeol; Kim, Taekyeong

    2014-12-01

    Time-dependent diffusion for Ag and Au metal atoms was measured using the scanning tunneling microscope break-junction technique in ambient conditions. We observed that Ag contacts do not form long single-atomic chains compared to Au contacts during the elongation of each metal electrode, and Ag atoms diffuse more quickly than Au atoms after metal contact rupture. This is consistent with previous results of molecular dynamic simulations. Further, we found a correlation between diffusion length and the evolution time on an atomic scale to reveal the time-dependent diffusion for Ag and Au metal atoms.

  18. Fabrication of low temperature cofired ceramic (LTCC) chip couplers for high frequencies : I. Effect of binder burnout process on the formation of electrode line

    Energy Technology Data Exchange (ETDEWEB)

    Cho, N.T.; Shim, K.B.; Lee, S.W. [Hanyang University, Seoul (Korea); Koo, K.D. [K-Cera Inc., Yongin (Korea)

    1999-06-01

    In the fabrication of ceramic chip couplers for high frequency applications such as the mobile communication equipment, the formation of electrode lines and Ag diffusion were investigated with heat treatment conditions for removing organic binders. The deformation and densification of the electrode line greatly depended on the binder burnout process due to the overlapped temperature zone near 400{sup o} C of the binder dissociation and the solid phase sintering of the silver electrode. Ag ions were diffused into the glass ceramic substrate. The Ag diffusion was led by the glassy phase containing Pb ions rather than by the crystalline phase containing Ca ions. The fact suggests that the Ag diffusion could be controlled by managing the composition of the glass ceramic substrate. 9 refs., 10 figs., 1 tab.

  19. Characterization and optimization of polymer electrolyte fuel cell electrodes

    Science.gov (United States)

    Boyer, Christopher Carter

    Experimental characterization and modeling were combined to find a procedure for optimizing the design of polymer electrolyte membrane fuel cell (PEMFC) electrodes. The mass transfer and kinetic properties of the active layer used in electrodes fabricated at the Center for Electrochemical Systems and Hydrogen Research (CESHR) were characterized as a function of electrolyte polymer content NafionRTM, DuPont, Fayetteville, NC) and catalyst loading for different types of platinum catalysts (E-Tek, Natick, MA). Expressions from limiting cases of the fuel cell model showed the combination of electrode materials for maximum current density at maximum catalyst utilization. Models describing the fuel cell behavior were selected and used to explain how different operating pressures affect the system power density and efficiency. An "inert layer" method was developed to determine the effective proton conductivity of the active layer. A "buffer layer" method was developed to determine the oxygen diffusivity in the gas pores. A review of the literature and experiments at CESHR was used to determine the oxygen reduction activity of the active layer. Finally, a fitting method was developed to measure the agglomerate diffusivity from cell tests. A PEMFC model demonstrated that operating the fuel cell pressurized can improve the power density at high currents because of oxygen mass transport. limitations in the substrate. However. as better electrode designs improve oxygen mass transfer, pressurized operation will lose this advantage. In addition, the model confirmed that oxygen enrichment systems require too much energy to separate oxygen from air to improve the net performance of a fuel cell. From limiting approximations of the solutions of the differential material balances in the fuel cell model, a simple set of analytical expressions were derived that predict the optimum active layer thickness and maximum current density based on the materials of construction and operating

  20. Using Diffusion Bonding in Making Piezoelectric Actuators

    Science.gov (United States)

    Sager, Frank E.

    2003-01-01

    A technique for the fabrication of piezoelectric actuators that generate acceptably large forces and deflections at relatively low applied voltages involves the stacking and diffusion bonding of multiple thin piezoelectric layers coated with film electrodes. The present technique stands in contrast to an older technique in which the layers are bonded chemically, by use of urethane or epoxy agents. The older chemical-bonding technique entails several disadvantages, including the following: It is difficult to apply the bonding agents to the piezoelectric layers. It is difficult to position the layers accurately and without making mistakes. There is a problem of disposal of hazardous urethane and epoxy wastes. The urethane and epoxy agents are nonpiezoelectric materials. As such, they contribute to the thickness of a piezoelectric laminate without contributing to its performance; conversely, for a given total thickness, the performance of the laminate is below that of a unitary piezoelectric plate of the same thickness. The figure depicts some aspects of the fabrication of a laminated piezoelectric actuator by the present diffusion- bonding technique. First, stock sheets of the piezoelectric material are inspected and tested. Next, the hole pattern shown in the figure is punched into the sheets. Alternatively, if the piezoelectric material is not a polymer, then the holes are punched in thermoplastic films. Then both faces of each punched piezoelectric sheet or thermoplastic film are coated with a silver-ink electrode material by use of a silkscreen printer. The electrode and hole patterns are designed for minimal complexity and minimal waste of material. After a final electrical test, all the coated piezoelectric layers (or piezoelectric layers and coated thermoplastic films) are stacked in an alignment jig, which, in turn, is placed in a curved press for the diffusion-bonding process. In this process, the stack is pressed and heated at a specified curing temperature

  1. High Precision Measurements of Carbon Disulfide Negative Ion Mobility and Diffusion

    CERN Document Server

    Snowden-Ifft, D P

    2013-01-01

    High precision measurements were made of mobility, lateral and longitudinal diffusion of CS2 negative ions in 40 Torr CS2 and 30 - 10 Torr CS2 - CF4. The mobility was found to be be 363.1 +/- 0.5 Torr cm2 / s V in CS2 and 408.0 +/- 0.8 Torr cm2 / s V in the CS2 - CF4 gas mixture. The lateral diffusion temperatures for these two gases (295 +/- 15 K and 297 +/- 6 K) were found to be in good agreement with room temperature. By contrast longitudinal diffusion temperature was found to be slightly elevated (319 +/- 10 (stat) +/- 8 (sys) K and 310 +/- 20 (stat) +/- 6 (sys) K) though given the errors, room temperature diffusion can not be ruled out. For lateral diffusion significant capture distances (0.21 +/- 0.07 mm and 0.15 +/- 0.03 mm) were measured while for longitudinal diffusion the results were not conclusive.

  2. A Novel Micro-hole Electrode Used to Investigate Electron Transfer Reactions at ITIES

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A novel micro-hole electrode was fabricated to investigate the electron transfer reaction at the interface between two immiscible electrolyte solutions (ITIES). The electron transfer reaction between ferro/ferricyanide in aqueous phase (W) and ferrocene in 1, 2-dichloroethane (O) phase was studied as a test experiment. The results showed that the diffusion coefficient obtained from the micro-hole electrode was consistent with that obtained at macro-interface. Due to its simplicity and the very small IR drop it will be a useful tool for the study of ITIES systems.

  3. A Novel Micro—hole Electrode Used to Investigate Electron Transfer Reactions at ITIES

    Institute of Scientific and Technical Information of China (English)

    DongPingZHAN; BingLiangWU

    2002-01-01

    A novel micro-hole electrode was fabricated to investigate the electron transfer reaction at the interface between two immiscible electrolyte solutions (ITIES). The electron transfer reaction between feero/ferricyanide in aqueous phase(W) and ferrocene in 1,2-dichloroethane (O) phase was studied as a test experiment. The results showed that the diffusion coefficient obtained from the micro-hole electrode was consistent with that obtained at macro-interface. Due to its simplicity and the very small IR drop it will be a useful tool for the study of ITIES systems.

  4. PEMFC electrode preparation: Influence of the solvent composition and evaporation rate on the catalytic layer microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, R.; Daza, L. [Instituto de Catalisis y Petroleoquimica, CSIC, C/ Marie Curie, 2, 28049 Madrid (Spain); Ferreira-Aparicio, P. [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Avda. Complutense, 22, 28040 Madrid (Spain)

    2005-10-10

    A series of parameters affecting the catalytic layer microstructure in polymer exchange fuel cell electrodes have been evaluated. The deposition of the catalytic layer in the gas diffusion support is shown to depend not only on the ink deposition method but also on the characteristics of the solvent used to disperse both the catalyst and the Nafion ionomer. The solvent viscosity and its dielectric constant are two important factors to control for the catalytic ink preparation. In particular, the solvent dielectric constant is shown to be directly related to the electrode performance in single cell tests. (author)

  5. Electrode process of La(Ⅲ) in molten LiCl-KCl

    Institute of Scientific and Technical Information of China (English)

    高繁星; 王长水; 刘利生; 郭建华; 常尚文; 常利; 李瑞雪; 欧阳应根

    2009-01-01

    The electrode process of La(Ⅲ) at Mo electrode in the molten LiCl-KCl for temperatures ranging from 683 K to 773 K was studied by cyclic voltammetry and chronopotentiometry,respectively.The results showed that in the molten LiCl-KCl,reduction of La(Ⅲ) occurred in a step with a global exchange of three electrons.Cyclic voltammetry studies indicated that at a sweep rate lower than 0.2 V/s,the electroreduction of La(Ⅲ) to lanthanum metal was reversible and controlled by diffusion of La(Ⅲ).However,the process b...

  6. Long life lithium batteries with stabilized electrodes

    Science.gov (United States)

    Amine, Khalil; Liu, Jun; Vissers, Donald R.; Lu, Wenquan

    2009-03-24

    The present invention relates to non-aqueous electrolytes having electrode stabilizing additives, stabilized electrodes, and electrochemical devices containing the same. Thus the present invention provides electrolytes containing an alkali metal salt, a polar aprotic solvent, and an electrode stabilizing additive. In some embodiments the additives include a substituted or unsubstituted cyclic or spirocyclic hydrocarbon containing at least one oxygen atom and at least one alkenyl or alkynyl group. When used in electrochemical devices with, e.g., lithium manganese oxide spinel electrodes or olivine or carbon-coated olivine electrodes, the new electrolytes provide batteries with improved calendar and cycle life.

  7. Diagnosing and treating lateral epicondylitis.

    OpenAIRE

    1994-01-01

    Lateral epicondylitis is often encountered in primary care. Although its diagnosis can be fairly straightforward, its treatment is often difficult. This review examines the epidemiology, pathophysiology, and clinical presentation of tennis elbow. Management options are discussed.

  8. Lateral inhibition during nociceptive processing

    DEFF Research Database (Denmark)

    Quevedo, Alexandre S.; Mørch, Carsten Dahl; Andersen, Ole Kæseler

    2017-01-01

    of skin. Thus, the stimulation of the skin region between the endpoints of the lines appears to produce inhibition. These findings indicate that lateral inhibition limits spatial summation of pain and is an intrinsic component of nociceptive information processing. Disruption of such lateral inhibition......Spatial summation of pain is the increase of perceived intensity that occurs as the stimulated area increases. Spatial summation of pain is sub-additive in that increasing the stimulus area produces a disproportionately small increase in the perceived intensity of pain. A possible explanation...... for sub-additive summation may be that convergent excitatory information is modulated by lateral inhibition. To test the hypothesis that lateral inhibition may limit spatial summation of pain, we delivered different patterns of noxious thermal stimuli to the abdomens of 15 subjects using a computer...

  9. Lateral gene transfer, rearrangement, reconciliation

    NARCIS (Netherlands)

    Patterson, M.D.; Szollosi, G.; Daubin, V.; Tannier, E.

    2013-01-01

    Background. Models of ancestral gene order reconstruction have progressively integrated different evolutionary patterns and processes such as unequal gene content, gene duplications, and implicitly sequence evolution via reconciled gene trees. These models have so far ignored lateral gene transfer,

  10. Cerebral Laterality and Verbal Processes

    Science.gov (United States)

    Sherman, Jay L.; And Others

    1976-01-01

    Research suggests that we process information by way of two distinct and functionally separate coding systems. Their location, somewhat dependent on cerebral laterality, varies in right- and left-handed persons. Tests this dual coding model. (Editor/RK)

  11. Method for manufacturing magnetohydrodynamic electrodes

    Science.gov (United States)

    Killpatrick, Don H.; Thresh, Henry R.

    1982-01-01

    A method of manufacturing electrodes for use in a magnetohydrodynamic (MHD) generator comprising the steps of preparing a billet having a core 10 of a first metal, a tubular sleeve 12 of a second metal, and an outer sheath 14, 16, 18 of an extrusile metal; evacuating the space between the parts of the assembled billet; extruding the billet; and removing the outer jacket 14. The extruded bar may be made into electrodes by cutting and bending to the shape required for an MDH channel frame. The method forms a bond between the first metal of the core 10 and the second metal of the sleeve 12 strong enough to withstand a hot and corrosive environment.

  12. Solid-Oxide Fuel Cell Electrode Microstructures: Making Sense of the Internal Framework Affecting Gas Transport

    Science.gov (United States)

    Hanna, Jeffrey

    Optimal electrodes for solid-oxide fuel cells will combine high porosity for gas diffusion, high phase connectivity for ion and electron conduction, and high surface area for chemical and electrochemical reactions. Tracer-diffusion simulations are used to gain a better understanding of the interplay between microstructure and transport in porous materials. Results indicate that the coefficient of diffusion through a porous medium is a function of the details of the internal geometry (microscopic) and porosity (macroscopic). I report that current solid-oxide fuel cell electrodes produced from high-temperature sintering of ceramic powders severely hinder gas transport because the resulting structures are highly tortuous, complex three-dimensional networks. In addition, poor phase connectivities will assuredly limit ion and electron transport, as well as the density of active sites for power-producing reactions. With new access to a wide range of technologies, micro- and nano-fabrication capabilities, and high-performance materials, there is a new ability to engineer the fuel cell electrode architecture, optimizing the physical processes within, increasing performance, and greatly reducing cost per kilowatt. Even simple packed-sphere and inverse-opal architectures will increase gas diffusion by an order of magnitude, and provide a higher level of connectivity than traditional powder-based structures.

  13. DIFFUSE DBD IN ATMOSPHERIC AIR AT DIFFERENT APPLIED PULSE WIDTHS

    Directory of Open Access Journals (Sweden)

    Ekaterina Alexandrovna Shershunova

    2015-02-01

    Full Text Available The paper deals with the realization and the diagnostics of the volume diffuse dielectric barrier discharge in 1-mm air gap when applying high voltage rectangular pulses to the electrodes. The effect of the applied pulse width on the discharge dissipated energy was studied in detail. It was found experimentally, the energy stayed nearly constant with the pulse elongation from 600 ns to 1 ms.

  14. Lateral Asymmetries in Human Evolution

    OpenAIRE

    John L. Bradshaw; Nettleton, Norman C.

    1989-01-01

    Lateral asymmetries are not confined to humans. Palaeozoic trilobites and calcichordates are now known to have been asymmetrical; song control in passerines is vested in the left cerebral hemisphere; learning which is lateralized to the left forebrain of chicks includes imprinting, visual discrimination learning and auditory habituation, while responses to novelty, attack and copulation are activated by the right; in rats the right hemisphere is involved in emotional behavior and spatial disc...

  15. CT navigated lateral interbody fusion.

    Science.gov (United States)

    Drazin, Doniel; Liu, John C; Acosta, Frank L

    2013-10-01

    Lateral interbody fusion techniques are heavily reliant on fluoroscopy for retractor docking and graft placement, which expose both the patient and surgeon to high doses of radiation. Use of image-guided technologies with CT-based images, however, can eliminate this radiation exposure for the surgeon. We describe the surgical technique of performing lateral lumbar interbody fusion using CT navigation. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Dual frequency dielectrophoresis with interdigitated sidewall electrodes for microfluidic flow-through separation of beads and cells.

    Science.gov (United States)

    Wang, Lisen; Lu, Jente; Marchenko, Steven A; Monuki, Edwin S; Flanagan, Lisa A; Lee, Abraham P

    2009-03-01

    This paper presents a novel design and separation strategy for lateral flow-through separation of cells/particles in microfluidics by dual frequency coupled dielectrophoresis (DEP) forces enabled by vertical interdigitated electrodes embedded in the channel sidewalls. Unlike field-flow-fractionation-DEP separations in microfluidics, which utilize planar electrodes on the microchannel floor to generate a DEP force to balance the gravitational force and separate objects at different height locations, lateral separation is enabled by sidewall interdigitated electrodes that are used to generate non-uniform electric fields and balanced DEP forces along the width of the microchannel. In the current design, two separate AC electric fields are applied to two sets of independent interdigitated electrode arrays fabricated in the sidewalls of the microchannel to generate differential DEP forces that act on the cells/particles flowing through. Individual particles (cells or beads) will experience DEP forces differently due to the difference in their dielectric properties. The balance of the differential DEP forces from the electrode arrays will position dissimilar particles at distinct equilibrium planes across the width of the channel. When coupled with fluid flow, this results in lateral separation along the width of the microchannel and the separated particles can thus be automatically directed into branched channel outlets leading to different reservoirs for downstream processing. In this paper, we present the design and analysis of lateral separation enabled by dual frequency coupled DEP, and cell/bead and cell/cell separations are demonstrated with this lateral separation strategy. With vertical interdigitated electrodes on the sidewall, the height of the microchannel can be increased without losing the electric field strength in contrast to other multiple frequency DEP devices with planar electrodes. As a result, populations of cells can be separated simultaneously

  17. Surface modification of recording electrodes

    OpenAIRE

    Iaci Miranda Pereira; Sandhra Maria de Carvalho; Rodrigo Lambert Oréfice; Marcelo Bariatto Andrade Fontes; Lilian Anee Muniz Arantes; Núbia Figueiró; Maria de Fátima Leite; Hercules Pereira Neves

    2013-01-01

    Waterborne Polyurethanes (PUs) are a family of polymers that contains urethane linkages synthesized in an aqueous environment and are thus free of organic solvents. Recently, waterborne PUs have been extensively studied for biomedical applications because of their biocompatibility. The present work investigates the following: (1) the impact on electrical performance of electrode materials (platinum and silicon) modified chemically by a layer of waterborne PU, and (2) the behavior of rat cardi...

  18. Multiplexed DNA-Modified Electrodes

    OpenAIRE

    Slinker, Jason D.; Muren, Natalie B.; Gorodetsky, Alon A.; Barton, Jacqueline K.

    2010-01-01

    We report the use of silicon chips with 16 DNA-modified electrodes (DME chips) utilizing DNA-mediated charge transport for multiplexed detection of DNA and DNA-binding protein targets. Four DNA sequences were simultaneously distinguished on a single DME chip with fourfold redundancy, including one incorporating a single base mismatch. These chips also enabled investigation of the sequence-specific activity of the restriction enzyme Alu1. DME chips supported dense DNA monolayer formation with ...

  19. A dry electrode for EEG recording.

    Science.gov (United States)

    Taheri, B A; Knight, R T; Smith, R L

    1994-05-01

    This paper describes the design, fabrication and testing of a prototype dry surface electrode for EEG signal recording. The new dry electrode has the advantages of no need for skin preparation or conductive paste, potential for reduced sensitivity to motion artifacts and an enhanced signal-to-noise ratio. The electrode's sensing element is a 3 mm stainless steel disk which has a 2000 A (200 nm) thick nitride coating deposited onto one side. The back side of the disk is attached to an impedance converting amplifier. The prototype electrode was mounted on a copper plate attached to the scalp by a Velcro strap. The performance of this prototype dry electrode was compared to commercially available wet electrodes in 3 areas of electroencephalogram (EEG) recording: (1) spontaneous EEG, (2) sensory evoked potentials, and (3) cognitive evoked potentials. In addition to the raw EEG, the power spectra of the signals from both types of electrodes were also recorded. The results suggest that the dry electrode performs comparably to conventional electrodes for all types of EEG signal analysis. This new electrode may be useful for the production of high resolution surface maps of brain activity where a large number of electrodes or prolonged recording times are required.

  20. Stretchable Micro-Electrode Array

    Energy Technology Data Exchange (ETDEWEB)

    Maghribi, M; Hamilton, J; Polla, D; Rose, K; Wilson, T; Krulevitch, P

    2002-03-08

    This paper focuses on the design consideration, fabrication processes and preliminary testing of the stretchable micro-electrode array. We are developing an implantable, stretchable micro-electrode array using polymer-based microfabrication techniques. The device will serve as the interface between an electronic imaging system and the human eye, directly stimulating retinal neurons via thin film conducting traces and electroplated electrodes. The metal features are embedded within a thin ({approx}50 micron) substrate fabricated using poly (dimethylsiloxane) (PDMS), a biocompatible elastomeric material that has very low water permeability. The conformable nature of PDMS is critical for ensuring uniform contact with the curved surface of the retina. To fabricate the device, we developed unique processes for metalizing PDMS to produce robust traces capable of maintaining conductivity when stretched (5%, SD 1.5), and for selectively passivating the conductive elements. An in situ measurement of residual strain in the PDMS during curing reveals a tensile strain of 10%, explaining the stretchable nature of the thin metalized devices.

  1. Redox electrode materials for supercapatteries

    Science.gov (United States)

    Yu, Linpo; Chen, George Z.

    2016-09-01

    Redox electrode materials, including transition metal oxides and electronically conducting polymers, are capable of faradaic charge transfer reactions, and play important roles in most electrochemical energy storage devices, such as supercapacitor, battery and supercapattery. Batteries are often based on redox materials with low power capability and safety concerns in some cases. Supercapacitors, particularly those based on redox inactive materials, e.g. activated carbon, can offer high power output, but have relatively low energy capacity. Combining the merits of supercapacitor and battery into a hybrid, the supercapattery can possess energy as much as the battery and output a power almost as high as the supercapacitor. Redox electrode materials are essential in the supercapattery design. However, it is hard to utilise these materials easily because of their intrinsic characteristics, such as the low conductivity of metal oxides and the poor mechanical strength of conducting polymers. This article offers a brief introduction of redox electrode materials, the basics of supercapattery and its relationship with pseudocapacitors, and reviews selectively some recent progresses in the relevant research and development.

  2. Electrode materials for rechargeable battery

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Christopher; Kang, Sun-Ho

    2015-09-08

    A positive electrode is disclosed for a non-aqueous electrolyte lithium rechargeable cell or battery. The electrode comprises a lithium containing material of the formula Na.sub.yLi.sub.xNi.sub.zMn.sub.1-z-z'M.sub.z'O.sub.d, wherein M is a metal cation, x+y>1, 0electrode material can be synthesized using an ion-exchange reaction with a lithium salt in an organic-based solvent to partially replace sodium ions of a precursor material with lithium ions.

  3. Peltier effects in electrode carbon

    Science.gov (United States)

    Hansen, Ellen Marie; Egner, Espen; Kjelstrup, Signe

    1998-02-01

    The thermoelectric power of a cell with platinum electrodes and a carbon conductor was determined. The electromotive force (emf) was measured as a function of the temperature difference between the electrodes at temperatures varying from 310 °C to 970 °C. From these measurements, the transported entropy of electric charge in carbon was found to vary from -1.7 to -1.9 J/(K mole) at temperatures around 300 °C, from -2.0 to -2.3 J/(K mole) at temperatures around 550 °C, and from -3.4 to -3.7 J/(K mole) at temperatures around 950 °C. This transported entropy had not before been determined for temperatures above 550 °C. Also, it is shown how the previously neglected surface properties can be taken into account to interpret the measurements. In the Hall-Héroult cell, the anode is made of a similar kind of carbon. Hence, the transported entropy found above can be used to describe the often neglected coupling between transport of heat and electric charge in this electrode. It is shown that the calculated electric potential profile through a coal sample will change significantly if the coupling is neglected, but the calculated temperature profile is independent of whether the coupling is neglected. New equations are also developed that can be used to evaluate the importance of the coupling in other systems.

  4. Surface modification of recording electrodes

    Directory of Open Access Journals (Sweden)

    Iaci Miranda Pereira

    2013-01-01

    Full Text Available Waterborne Polyurethanes (PUs are a family of polymers that contains urethane linkages synthesized in an aqueous environment and are thus free of organic solvents. Recently, waterborne PUs have been extensively studied for biomedical applications because of their biocompatibility. The present work investigates the following: (1 the impact on electrical performance of electrode materials (platinum and silicon modified chemically by a layer of waterborne PU, and (2 the behavior of rat cardiac fibroblasts and rat cardiomyocytes when in contact with an electrode surface. Diisocyanate and poly(caprolactone diol were the main reagents for producing PUs. The electrochemical impedance of the electrode/electrolyte interface was accessed by electrochemical impedance spectroscopy. The cellular viability, proliferation, and morphology changes were investigated using an MTT assay. Cardiomyocyte adherence was observed by scanning electron microscopy. The obtained surface was uniform, flat, and transparent. The film showed good adhesion, and no peeling was detected. The electrochemical impedance decreased over time and was influenced by the ionic permeability of the PU layer. The five samples did not show cytotoxicity when in contact with neonatal rat cells.

  5. Diffusion Based Photon Mapping

    DEFF Research Database (Denmark)

    Schjøth, Lars; Olsen, Ole Fogh; Sporring, Jon

    2006-01-01

    . To address this problem we introduce a novel photon mapping algorithm based on nonlinear anisotropic diffusion. Our algorithm adapts according to the structure of the photon map such that smoothing occurs along edges and structures and not across. In this way we preserve the important illumination features......, while eliminating noise. We call our method diffusion based photon mapping....

  6. Diffusion Based Photon Mapping

    DEFF Research Database (Denmark)

    Schjøth, Lars; Fogh Olsen, Ole; Sporring, Jon

    2007-01-01

    . To address this problem we introduce a novel photon mapping algorithm based on nonlinear anisotropic diffusion. Our algorithm adapts according to the structure of the photon map such that smoothing occurs along edges and structures and not across. In this way we preserve the important illumination features......, while eliminating noise. We call our method diffusion based photon mapping....

  7. Bronnen van diffuse bodembelasting

    NARCIS (Netherlands)

    Lijzen JPA; Ekelenkamp A; LBG; DGM/BO

    1995-01-01

    Ten behoeve van het preventieve bodembeleid was onvoldoende duidelijk welke bijdrage diverse bronnen leveren aan diffuse bodembelasting. Doel van deze inventarisatie was beschikbare kennis over diffuse bodembelasting te bundelen en kennis-lacunes aan te geven. Nevendoel is het beschrijven van de

  8. Distributed Control Diffusion

    DEFF Research Database (Denmark)

    Schultz, Ulrik Pagh

    2007-01-01

    , self-reconfigurable robots, we present the concept of distributed control diffusion: distributed queries are used to identify modules that play a specific role in the robot, and behaviors that implement specific control strategies are diffused throughout the robot based on these role assignments...... perform simple obstacle avoidance in a wide range of different car-like robots constructed using ATRON modules...

  9. Electrochemical Techniques for Intercalation Electrode Materials in Rechargeable Batteries.

    Science.gov (United States)

    Zhu, Yujie; Gao, Tao; Fan, Xiulin; Han, Fudong; Wang, Chunsheng

    2017-03-16

    Understanding of the thermodynamic and kinetic properties of electrode materials is of great importance to develop new materials for high performance rechargeable batteries. Compared with computational understanding of physical and chemical properties of electrode materials, experimental methods provide direct and convenient evaluation of these properties. Often, the information gained from experimental work can not only offer feedback for the computational methods but also provide useful insights for improving the performance of materials. However, accurate experimental quantification of some properties can still be challenging. Among them, chemical diffusion coefficient is one representative example. It is one of the most crucial parameters determining the kinetics of intercalation compounds, which are by far the dominant electrode type used in rechargeable batteries. Therefore, it is of significance to quantitatively evaluate this parameter. For this purpose, various electrochemical techniques have been invented, for example, galvanostatic intermittent titration technique (GITT), potentiostatic intermittent titration technique (PITT), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). One salient advantage of these electrochemical techniques over other characterization techniques is that some implicit thermodynamic and kinetic quantities can be linked with the readily measurable electrical signals, current, and voltage, with very high precision. Nevertheless, proper application of these techniques requires not just an understanding of the structure and chemistry of the studied materials but sufficient knowledge of the physical model for ion transport within solid host materials and the analysis method to solve for chemical diffusion coefficient. Our group has been focusing on using various electrochemical techniques to investigate battery materials, as well as developing models for studying some emerging materials. In this Account, the

  10. Understanding the influence of the electrode material on microbial fuel cell performance

    Science.gov (United States)

    Sanchez, David V. P.

    In this thesis, I deploy sets of electrodes into microbial fuel cells (MFC), characterize their performance, and evaluate the influence of both platinum catalysts and carbon-based electrodes on current production. The platinum work centers on improving current production by optimizing the use of the catalyst using nano-fabrication techniques. The carbon-electrode work seeks to determine the influence of the bare electrode on biofilm-anode current production. The development of electrodes for MFCs has boomed over the past decade, however, experiments aimed at identifying how catalyst deposition methods and electrode properties influence current production have been limited. The research conducted here is an attempt to expand this knowledge base for platinum catalysts and carbon electrodes. In the initial chapters (4 and 5), I discuss our attempt to decrease catalyst loadings while increasing current production through the use of platinum nanoparticles. The results demonstrate that incorporating platinum nanoparticles throughout the anode and cathode is an efficient means of increasing MFC current production relative to surface deposition because it increases catalyst surface area. The later chapters (chapters 6 and 7) develop an understanding of the importance of electrode properties (i.e. surface area, activation resistance, conductivity, surface morphology) by electrochemically evaluating well-studied anode-respiring pure cultures on different carbon electrode architectures. Two different architectures are produced by using tubular and platelet shaped constituent materials (i.e. carbon fibers and graphene nanoplatelets) and the morphologies of the electrodes are varied by altering the size of the constituent material. The electrodes are characterized and evaluated in MFCs using either Shewanella oneidensis MR-1 or Geobacter sulfurreducens as the innoculant because their bioelectrochemical physiologies are the most documented in the literature. Using the

  11. Nanoparticle embedded enzymes for improved lateral flow sensors.

    Science.gov (United States)

    Özalp, Veli C; Zeydanlı, Uğur S; Lunding, Anita; Kavruk, Murat; Öz, M Tufan; Eyidoğan, Füsun; Olsen, Lars F; Öktem, Hüseyin A

    2013-08-01

    In this study, combining the nanoparticle embedded sensors with lateral flow assays, a novel strategy for ensuring the quality of signalling in lateral flow assays (LFAs) was developed. A LFA for reactive oxygen species (ROS) is reported that is based on horse radish peroxidase (HRP) which is co-entrapped with Texas Red dextran inside porous polyacrylamide nanoparticles. In this system, enzymes are protected in the porous matrix of polyacrylamide which freely allows the diffusion of the analyte. The sensor is rapid and sensitive for quantification of hydrogen peroxide concentrations. A test solution of hydrogen peroxides was quantified with this novel LFA-ROS sensor to obtain a linear range between 1 and 25 μM. Nanoparticle embedding of enzymes is proposed here as a general strategy for developing enzyme-based lateral flow assays, eliminating adverse effects associated with biological samples.

  12. Nanoparticle embedded enzymes for improved lateral flow sensors

    DEFF Research Database (Denmark)

    Özalp, Veli Cengiz; Zeydanlı, Uğur S.; Lunding, Anita

    2013-01-01

    In this study, combining the nanoparticle embedded sensors with lateral flow assays, a novel strategy for ensuring the quality of signalling in lateral flow assays (LFAs) was developed. A LFA for reactive oxygen species (ROS) is reported that is based on horse radish peroxidase (HRP) which is co......-entrapped with Texas Red dextran inside porous polyacrylamide nanoparticles. In this system, enzymes are protected in the porous matrix of polyacrylamide which freely allows the diffusion of the analyte. The sensor is rapid and sensitive for quantification of hydrogen peroxide concentrations. A test solution...... of hydrogen peroxides was quantified with this novel LFA-ROS sensor to obtain a linear range between 1 and 25 μM. Nanoparticle embedding of enzymes is proposed here as a general strategy for developing enzyme-based lateral flow assays, eliminating adverse effects associated with biological samples....

  13. Electrochemical Oxidation of Paracetamol Mediated by MgB2 Microparticles Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Mohammed Zidan

    2011-01-01

    Full Text Available A MgB2 microparticles modified glassy carbon electrode (MgB2/GCE was fabricated by adhering microparticles of MgB2 onto the electrode surface of GCE. It was used as a working electrode for the detection of paracetamol in 0.1 M KH2PO4 aqueous solution during cyclic voltammetry. Use of the MgB2/GCE the oxidation process of paracetamol with a current enhancement significantly by about 2.1 times. The detection limit of this modified electrode was found to be 30 μM. The sensitivity under conditions of cyclic voltammetry is significantly dependent on pH, supporting electrolyte, temperature and scan rate. The current enhancement observed in different electrolytic media varied in the following order: KH2PO4 > KCl > K2SO4 > KBr. Interestingly, the oxidation of paracetamol using modified GC electrode remain constant even after 15 cycling. It is therefore evident that the MgB2 modified GC electrode possesses some degree of stability. A slope of 0.52 dependent of scan rate on current indicates that the system undergoes diffusion-controlled process.

  14. Characterization and single cell testing of Pt/C electrodes prepared by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Martin, A.J.; Chaparro, A.M.; Gallardo, B.; Folgado, M.A. [CIEMAT, Department of Energy, Avda. Complutense 22, 28040 Madrid (Spain); Daza, L. [CIEMAT, Department of Energy, Avda. Complutense 22, 28040 Madrid (Spain); Instituto de Catalisis y Petroleoquimica (CSIC), C/. Marie Curie 2, Campus Cantoblanco, 28049 Madrid (Spain)

    2009-07-01

    Electrodes for proton exchange membrane fuel cells (PEMFC) have been prepared by the electrodeposition method. For this task, the electrodeposition of platinum is carried out on a carbon black substrate impregnated with an ionomer, proton conducting, medium. Before electrodeposition, the substrate is submitted to an activation process to increase the hydrophilic character of the surface to a few microns depth. Electrodeposition of platinum takes place inside the generated surface hydrophilic layer, resulting in a continuous phase covering totally or partially carbon substrate grains. Cross sectional images show a decay profile of platinum towards the interior of the substrate, reflecting a deposition process limited by diffusion of PtCl{sub 6}{sup 2-} through the porous substrate. Electrodes with different platinum loads have been prepared, and membrane electrode assemblies (MEA) have been mounted with the electrodeposited electrodes as cathode and other standard components (commercial anode and Nafion{sup R} 117 membrane). The electrochemically active surface area determined from hydrogen underpotential deposition charge, is lower on the electrodeposited electrodes than on standard electrodes. However, single cell testing shows higher mass specific activity on electrodeposited cathodes with low and intermediate Pt load (below 0.05 mg Pt cm{sup -2}). (author)

  15. Characterization and single cell testing of Pt/C electrodes prepared by electrodeposition

    Science.gov (United States)

    Martín, A. J.; Chaparro, A. M.; Gallardo, B.; Folgado, M. A.; Daza, L.

    Electrodes for proton exchange membrane fuel cells (PEMFC) have been prepared by the electrodeposition method. For this task, the electrodeposition of platinum is carried out on a carbon black substrate impregnated with an ionomer, proton conducting, medium. Before electrodeposition, the substrate is submitted to an activation process to increase the hydrophilic character of the surface to a few microns depth. Electrodeposition of platinum takes place inside the generated surface hydrophilic layer, resulting in a continuous phase covering totally or partially carbon substrate grains. Cross sectional images show a decay profile of platinum towards the interior of the substrate, reflecting a deposition process limited by diffusion of PtCl 6 2- through the porous substrate. Electrodes with different platinum loads have been prepared, and membrane electrode assemblies (MEA) have been mounted with the electrodeposited electrodes as cathode and other standard components (commercial anode and Nafion R 117 membrane). The electrochemically active surface area determined from hydrogen underpotential deposition charge, is lower on the electrodeposited electrodes than on standard electrodes. However, single cell testing shows higher mass specific activity on electrodeposited cathodes with low and intermediate Pt load (below 0.05 mg Pt cm -2).

  16. Atomic diffusion in stars

    CERN Document Server

    Michaud, Georges; Richer, Jacques

    2015-01-01

    This book gives an overview of atomic diffusion, a fundamental physical process, as applied to all types of stars, from the main sequence to neutron stars. The superficial abundances of stars as well as their evolution can be significantly affected. The authors show where atomic diffusion plays an essential role and how it can be implemented in modelling.  In Part I, the authors describe the tools that are required to include atomic diffusion in models of stellar interiors and atmospheres. An important role is played by the gradient of partial radiative pressure, or radiative acceleration, which is usually neglected in stellar evolution. In Part II, the authors systematically review the contribution of atomic diffusion to each evolutionary step. The dominant effects of atomic diffusion are accompanied by more subtle effects on a large number of structural properties throughout evolution. One of the goals of this book is to provide the means for the astrophysicist or graduate student to evaluate the importanc...

  17. Currents between tethered electrodes in a magnetized laboratory plasma

    Science.gov (United States)

    Stenzel, R. L.; Urrutia, J. M.

    1989-01-01

    Laboratory experiments on important plasma physics issues of electrodynamic tethers were performed. These included current propagation, formation of wave wings, limits of current collection, nonlinear effects and instabilities, charging phenomena, and characteristics of transmission lines in plasmas. The experiments were conducted in a large afterglow plasma. The current system was established with a small electron-emitting hot cathode tethered to an electron-collecting anode, both movable across the magnetic field and energized by potential difference up to V approx.=100 T(sub e). The total current density in space and time was obtained from complete measurements of the perturbed magnetic field. The fast spacecraft motion was reproduced in the laboratory by moving the tethered electrodes in small increments, applying delayed current pulses, and reconstructing the net field by a linear superposition of locally emitted wavelets. With this technique, the small-amplitude dc current pattern is shown to form whistler wings at each electrode instead of the generally accepted Alfven wings. For the beam electrode, the whistler wing separates from the field-aligned beam which carries no net current. Large amplitude return currents to a stationary anode generate current-driven microinstabilities, parallel electric fields, ion depletions, current disruptions and time-varying electrode charging. At appropriately high potentials and neutral densities, excess neutrals are ionized near the anode. The anode sheath emits high-frequency electron transit-time oscillations at the sheath-plasma resonance. The beam generates Langmuir turbulence, ion sound turbulence, electron heating, space charge fields, and Hall currents. An insulated, perfectly conducting transmission line embedded in the plasma becomes lossy due to excitation of whistler waves and magnetic field diffusion effects. The implications of the laboratory observations on electrodynamic tethers in space are discussed.

  18. Strategies for "wiring" redox-active proteins to electrodes and applications in biosensors, biofuel cells, and nanotechnology.

    Science.gov (United States)

    Nöll, Tanja; Nöll, Gilbert

    2011-07-01

    In this tutorial review the basic approaches to establish electrochemical communication between redox-active proteins and electrodes are elucidated and examples for applications in electrochemical biosensors, biofuel cells and nanotechnology are presented. The early stage of protein electrochemistry is described giving a short overview over electron transfer (ET) between electrodes and proteins, followed by a brief introduction into experimental procedures for studying proteins at electrodes and possible applications arising thereof. The article starts with discussing the electrochemistry of cytochrome c, the first redox-active protein, for which direct reversible ET was obtained, under diffusion controlled conditions and after adsorption to electrodes. Next, examples for the electrochemical study of redox enzymes adsorbed on electrodes and modes of immobilization are discussed. Shortly the experimental approach for investigating redox-active proteins adsorbed on electrodes is outlined. Possible applications of redox enzymes in electrochemical biosensors and biofuel cells working by direct ET (DET) and mediated ET (MET) are presented. Furthermore, the reconstitution of redox active proteins at electrodes using molecular wire-like units in order to "wire" the proteins to the electrode surface and possible applications in nanotechnology are discussed.

  19. High rate capabilities Fe3O4-based Cu nano-architectured electrodes for lithium-ion battery applications.

    Science.gov (United States)

    Taberna, P L; Mitra, S; Poizot, P; Simon, P; Tarascon, J-M

    2006-07-01

    All battery technologies are known to suffer from kinetic problems linked to the solid-state diffusion of Li in intercalation electrodes, the conductivity of the electrolyte in some cases and the quality of interfaces. For Li-ion technology the latter effect is especially acute when conversion rather than intercalation electrodes are used. Nano-architectured electrodes are usually suggested to enhance kinetics, although their realization is cumbersome. To tackle this issue for the conversion electrode material Fe3O4, we have used a two-step electrode design consisting of the electrochemically assisted template growth of Cu nanorods onto a current collector followed by electrochemical plating of Fe3O4. Using such electrodes, we demonstrate a factor of six improvement in power density over planar electrodes while maintaining the same total discharge time. The capacity at the 8C rate was 80% of the total capacity and was sustained over 100 cycles. The origin of the large hysteresis between charge and discharge, intrinsic to conversion reactions, is discussed and approaches to reduce it are proposed. We hope that such findings will help pave the way for the use of conversion reaction electrodes in future-generation Li-ion batteries.

  20. Theory of linear sweep voltammetry with diffuse charge: Unsupported electrolytes, thin films, and leaky membranes

    Science.gov (United States)

    Yan, David; Bazant, Martin Z.; Biesheuvel, P. M.; Pugh, Mary C.; Dawson, Francis P.

    2017-03-01

    Linear sweep and cyclic voltammetry techniques are important tools for electrochemists and have a variety of applications in engineering. Voltammetry has classically been treated with the Randles-Sevcik equation, which assumes an electroneutral supported electrolyte. In this paper, we provide a comprehensive mathematical theory of voltammetry in electrochemical cells with unsupported electrolytes and for other situations where diffuse charge effects play a role, and present analytical and simulated solutions of the time-dependent Poisson-Nernst-Planck equations with generalized Frumkin-Butler-Volmer boundary conditions for a 1:1 electrolyte and a simple reaction. Using these solutions, we construct theoretical and simulated current-voltage curves for liquid and solid thin films, membranes with fixed background charge, and cells with blocking electrodes. The full range of dimensionless parameters is considered, including the dimensionless Debye screening length (scaled to the electrode separation), Damkohler number (ratio of characteristic diffusion and reaction times), and dimensionless sweep rate (scaled to the thermal voltage per diffusion time). The analysis focuses on the coupling of Faradaic reactions and diffuse charge dynamics, although capacitive charging of the electrical double layers is also studied, for early time transients at reactive electrodes and for nonreactive blocking electrodes. Our work highlights cases where diffuse charge effects are important in the context of voltammetry, and illustrates which regimes can be approximated using simple analytical expressions and which require more careful consideration.