Electrode

A new approach for studying the effect of temperature on anodic oxide growth on aluminium is presented in this paper. Using an in-house developed electrode holder, anodizing is performed under conditions of applied and controlled electrode temperature. The influence of temperature on the process is evaluated by experiments in a broad temperature range for both the electrode and the electrolyte temperature. The electrochemical behaviour of the aluminium electrodes is demonstrated to be more susceptible to variations of the electrode temperature than to variations of the electrolyte temperature. Concerning the morphology of the anodic film it is shown that by cooling the electrode a normal oxide layer could be grown at high electrolyte temperatures, whereas anodizing in a cool electrolyte at high electrode temperature results in a collapsed porous structure at the oxide surface. Furthermore, the electrode temperature affects the formation ratio of the oxide to a larger extent than the electrolyte temperature, indicating its important influence even on the level of the ionic conductivity during anodic oxide growth. All observations indicate that merely considering the electrolyte temperature upon studying the influence of temperature on the process is not sufficient; the electrode temperature is much more determining.

Background-The anisotropy of cardiac tissue is a key determinant of 3D electric propagation and the stability of activation wave fronts in the heart. The electric properties of ventricular myocardium are widely assumed to be axially anisotropic, with activation propagating most rapidly in the myofiber direction and at uniform velocity transverse to this. We present new experimental evidence that contradicts this view. Methods and Results-For the first time, high-density intramural electric mapping (325 electrodes at Ϸ4ϫ4ϫ1-mm spacing) from pig left ventricular tissue was used to reconstruct 3D paced activation surfaces projected directly onto 3D tissue structure imaged throughout the same left ventricular volume. These data from 5 hearts demonstrate that ventricular tissue is electrically orthotropic with 3 distinct propagation directions that coincide with local microstructural axes defined by the laminar arrangement of ventricular myocytes. The maximum conduction velocity of 0.67Ϯ0.019 ms Ϫ1 was aligned with the myofiber axis. However, transverse to this, the maximum conduction velocity was 0.30Ϯ0.010 ms Ϫ1 , parallel to the myocyte layers and 0.17Ϯ0.004 ms Ϫ1 normal to them. These orthotropic conduction velocities give rise to preferential activation pathways across the left ventricular free wall that are not captured by structurally detailed computer models, which incorporate axially anisotropic electric properties. Conclusions-Our findings suggest that current views on uniform side-to-side electric coupling in the heart need to be revised. In particular, nonuniform laminar myocardial architecture and associated electric orthotropy should be included in future models of initiation and maintenance of ventricular arrhythmia. (Circ Arrhythmia Electrophysiol. 2009;2:433-440.)

Electrical resistivity tomography ͑ERT͒ has shown great promise for monitoring transient hydrologic processes. One advantage of ERT under those conditions is the ability of a user to tailor the spatial sensitivity of an ERT survey through selection of electrode locations and electrode combinations. Recent research has shown that quadripoles can be selected in a manner that improves the independent inversion of ERT data. Our ultimate interest lies in using ERT data along with measurements from other sensors, which typically can provide high-quality data from shallow regions of the subsurface, in a joint inversion. As a result, we do not consider the selection of quadripoles specifically for inde-pendent ERT inversion. Rather, we present an approach to focusthe spatial sensitivity of ERT surveys in specific subsurface regions with the assumption that those data, when interpreted along with other measurements that are sensitive to those regions, will lead to more complete hydrologic characterization. Because we are interested in monitoring rapid processes, our approach is designed to efficiently identify optimal quadripoles. This is achieved by separating the optimization from the inversion grid, significantly reducing computational effort. We extend our previous work to consider the use of both surface and borehole ERT electrodes and to consider the impacts of horizontally layered electrical conductivity conditions. Results confirm the ability of the method to focus survey sensitivity while showing the importance of incorporation of prior knowledge of the subsurface electric conductivity structure in designing optimal ERT surveys.

The uncertain conductivity value of skull and brain tissue influences the accuracy of the electroencephalogram (EEG) inverse problem solution. Indeed, when the assumed conductivity in the numerical procedure is different from the actual conductivity then a source localization error is introduced. When using traditional least-squares minimization methods, the number of electrodes in the EEG cap does not influence the spatial resolution. A recently developed reduced conductivity dependence (RCD) methodology, based on the selection of electrodes, is able to increase the spatial resolution of the EEG inverse problem. This paper presents the implications of the RCD method when using a large number of electrodes in the EEG cap on the spatial resolution of the EEG inverse solutions. We show by means of numerical experiments that in contrast to traditional methods, the RCD method enables to increase the spatial resolution. The computations show that the EEG hardware should be modified with as large as possible electrodes.

This paper describes the development of electrochemical processes for the oxidative degradation of toxic organic chemicals in waste waters. Doped bismuth lead dioxide anodes have been tested by the kinetic study of phenol anodic oxidation in aqueous solution. The main products ...

Purpose: To determine the cerebral electroencephalography (EEG) substrates of scalp EEG seizure patterns, such as source area and synchrony, and in so doing assess the limitations of scalp seizure recording in the localization of seizure onset zones in patients with temporal lobe epilepsy. Methods: We recorded simultaneously 26 channels of scalp EEG with subtemporal supplementary electrodes and 46-98 channels of intracranial EEG in presurgical candidates with temporal lobe epilepsy. We correlated intracranial EEG source area and synchrony at seizure onset with the corresponding scalp EEG. Eighty-six simultaneous intracranial-and scalp-recorded seizures from 23 patients were evaluated. Results: Thirty-four intracranial ictal discharges (40%) from 9 patients (39%) had sufficient cortical source area (namely > 10 cm 2 ) and synchrony at seizure onset to produce a simultaneous or nearly simultaneous focal scalp EEG ictal pattern.

The differential capacitance of the electrical double layer at glassy carbon, platinum and gold electrodes immersed in various ionic liquids was measured using impedance spectroscopy. We discuss the influence of temperature, the composition of the ionic liquids and the electrode material on the differential capacitance/potential curves. For different systems these curves have various overall shapes, but all include several extremes and a common minimum near the open circuit potential. We attribute this minimum to the potential of zero charge (PZC). Significantly, the differential capacitance generally decreases if the applied potential is large and moving away from the PZC. This is attributed to lattice saturation [A. A. Kornyshev, J. Phys. Chem. B, 2007, 111, 5545] effects which result in a thicker double layer. The differential capacitance of the double layer grows and specific adsorption diminishes with increasing temperature. Specific adsorption of both cations and anions influences the shapes of curves close to the PZC. The general shape of differential capacitance/potential does not depend strongly on the identity of the electrode material.

The molten salt electrolytic method for the preparation of nano-structured carbon materials has been subjected to a systematic investigation. It has been confirmed that the electrolysis of molten lithium chloride in the presence of a graphite cathode generates a carbonaceous product that contains nanostructured constituents like particles, fibres and tubes. It has furthermore been found that the precise composition of the product depends critically on a number of process parameters, namely, type of graphite material, reaction temperature, electrochemical polarisation regime, and reaction time. After careful optimisation of these parameters, it has become possible to achieve a content of nanotubes in the carbonaceous product of approximately 80%. This exceeds by far the results of all previous studies using this approach. The nanotubes synthesised are multi-walled with varying diameters and highly curved, and they occur in the form of aggregates of considerable size.

Objective: To establish a reliable technique for nerve conduction study (NCS) of medial and lateral branches of the superficial radial nerve (SRN). Methods: The distribution of SRN and its branches were examined in 10 cadavers. Based on the cadaveric study, anti-dromic nerve conduction studies were performed on 31 healthy subjects. Results: The SRN became superficial approximately 8.4 cm from the radial styloid process (RS) and divided into medial and lateral branches 4.9 cm proximal to RS. The medial branch divided into two branches: proximal to extensor pollicis longus (EPL) tendon in 16 hands. The lateral branch ran parallel and 0.2 cm lateral to abductor pollicis longus (APL) tendon. Sensory nerve action potential (SNAP) was significantly shorter in latencies when recording over snuff box, compared with that from the EPL and APL tendons. SNAP obtained from APL tendon was significantly smaller in amplitude, compared with those from snuff box and EPL tendon. Conclusions: Anti-dromic stimulation of SRN should be performed 10 cm proximal to the recording electrode. The optimal recording position for each branch of SRN is snuff box for medial branch, and lateral to APL tendon for lateral branch. Significance: The SRN can be evaluated appropriately by NCS of medial and lateral branches of SRN.

Electrochemical properties of glassy carbon electrodes of two types were examined, one thermally treated at 10008C (sample K) and another thermally treated at 25008 (sample G). Mechanically polished or electrochemically polarized electrodes were characterized in NaOH, HClO and H SO solutions by cyclic voltammetry (cv) at different sweep rates in 4 2 4 the potential range between the hydrogen and oxygen evolution. The activity of the electrodes depended on the properties of the glassy carbon examined, as determined by both the temperature of thermal treatment and the mechanical or electrochemical pretreatment of the sample. It was noticed that both types of electrodes, when polished exhibited an increase in the double layer charge upon increasing the pH value of the solution. The cv charges, for both types of samples, increase upon anodic polarization. The higher the potential of oxidation, the more pronounced is the increase in charge, particularly in 22 acidic solution. The increase in charge amounts from below 1 mC cm for polished glassy carbon up to few hundreds of 22 mC cm for surfaces anodically polarized in acidic solution. Analysis of the dependence of voltammetric charge, as well as morphological changes of the electrode surface, on the time of oxidation suggests the existence of three stages in the electrochemical activation process. The first one occurs only once at the beginning of the activation, while the other two repeat themselves, reflecting a periodical activation and deactivation process. These stages were discussed and ascribed to a surface layer oxidation, graphite oxide layer growth and mechanical destruction of the surface. Independent surface analysis by AES, XPS and STM confirms the results obtained by electrochemical methods.

The detection of buried land mines in soil is a well-studied problem; many existing technologies are designed and optimized for performance in different soil types. Research on mine detection in shallow water environments such as beaches, however, is much less developed. Electrical impedance tomography (EIT) shows promise for this application. EIT uses current-stimulating and voltage-recording electrode pairs to measure trans-impedances in the volume directly beneath the electrode array, which sits flat over the ground surface. The trans-impedances are used to construct a conductivity profile of the volume. Non-metallic and metallic explosives appear as perturbations in the conductivity profile, and their location and size can be estimated. Lab testing has yielded promising results using a submerged array positioned over a sand bed. The instrument has also successfully detected surrogate mines in a traditional soil environment during field trials. Resolution of the detector is roughly half the pitch of electrodes in the array. In underwater lab testing, non-conducting targets buried in the sand are detected at a depth of 1.5 times the electrode pitch with the array positioned up to one electrode pitch above the sand bed. Results will be presented for metallic and non-metallic targets of various shapes and sizes.

A dye-sensitized solar cell based on TiO2 electrode was prepared by mixing the TiO2 nanopowder and TiCl4 aqueous solution, in which the mixture was used as the paste to deposit onto the fluorine doped tin oxide (FTO) coated glass substrates by screen-printing method. DSSC were created after a rinse of TiO2 electrode with acetonitrile to remove excess dye molecules. The synthesis and characterization of the TiO2 paste was figured out by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The TiO2 layer is homogeneous and composed of anatase and rutile particles. The photocurrent-voltage of the cell was fabricated and the comparison dye was made by using the eosin Y and N719. The sample that use N719 dye showed the better result which is generating a short-circuit photocurrent density of 0.0299 mA/cm2, an open-circuit voltage of 0.713 V, and the energy conversion efficiency was 0.08926 %.

Objective: Electroencephalography (EEG) is an important tool for studying the temporal dynamics of the human brain's large-scale neuronal circuits. However, most EEG applications fail to capitalize on all of the data's available information, particularly that concerning the location of active sources in the brain. Localizing the sources of a given scalp measurement is only achieved by solving the so-called inverse problem. By introducing reasonable a priori constraints, the inverse problem can be solved and the most probable sources in the brain at every moment in time can be accurately localized.

A new approach for studying the effect of temperature on electrochemical processes is presented in this paper. Using an in-house developed electrode holder, experiments are performed under conditions of applied and controlled electrode temperature. This new approach provides an improved temperature control during the experimental study and, additionally, allows distinguishing both the influences of the electrolyte and electrode temperatures. The advantages of the applied electrode temperature approach are illustrated by considering porous anodizing of aluminium. In a broad temperature range the electrochemical behaviour of the aluminium electrodes, recorded during the new and the conventional way of anodizing, are compared. Differences between the anodic potential evolutions in both approaches are observed, and are explained by a heat flux to the surroundings during the experiments at uncontrolled electrode temperature. These results illustrate the advantage of applying the electrode temperature. If the influence of temperature on a process is investigated by merely varying the electrolyte temperature, the electrode temperature is only indirectly influenced and can significantly differ from the electrolyte temperature. Therefore, when evaluating the influence of temperature on an electrochemical system the electrode temperature should be considered, and preferentially also controlled.

This article describes the first attempt to conduct electrical resistivity tomography (ERT) in solid permafrost-affected rock faces. Electrode design, instrument settings, and processing routines capable of measuring under relevant conditions were developed. Four transects, with ...

Electrical resistivity tomography was used in order to explore an experimental site of the LaSalle Beauvais Polytechnic Institute (France). The test was conducted along a profile line of 315 m length, using 64 electrodes deployed at an interelectrode spacing of 5 m, and the data were recorded using gradient, Wenner and pole-dipole arrays. The performance of plate electrodes (non-conventional flat-based) is compared with the performance of peak electrodes (conventional spike). The hydrogeophysical investigation of the chalk aquifer system of Beauvais shows that the performance of plate electrodes is satisfactory, leading to inversions of small root-mean-square errors. Peak and the plate electrodes were tested before and after injection of a salt tracer in the piezometer of the experimental site. The study demonstrates the usefulness of plate electrodes (efficient, less time consuming) and the possibility of aquifer characterization by a salt tracer.

Pyridine Boron Trifluoride (PBF)-based electrolyte additive blends for Li[Ni0.42Mn0.42Co0.16]O2 (NMC442)/graphite pouch cells have been systematically investigated. Other additives investigated in the blends included methylene methane disulfonate (MMDS) and ethylene sulfate (DTD). Ultra-high precision coulometry (UHPC), electrochemical impedance spectroscopy (EIS), gas evolution and long-term cycling experiments were made. The results obtained in this work indicate that MMDS and DTD have good compatibility with PBF-type additives and some of their combinations showed significant improvements in coulombic efficiency, reducing impedance and maintaining good capacity retention during high-voltage cycling compared to PBF-type additives alone.

Objective: Electroencephalography (EEG) is an important tool for studying the temporal dynamics of the human brain's large-scale neuronal circuits. However, most EEG applications fail to capitalize on all of the data's available information, particularly that concerning the location of active sources in the brain. Localizing the sources of a given scalp measurement is only achieved by solving the so-called inverse problem. By introducing reasonable a priori constraints, the inverse problem can be solved and the most probable sources in the brain at every moment in time can be accurately localized.

We have developed a new and very simple method for determining the solubility of gases in aqueous solutions, by using the Bunsen coefficient value. The procedure is based on an electrochemical measurement. By means of a reliable relationship between this electrical measurement and the gas concentration in the gas phase above the aqueous solution, the Bunsen coefficient value for this gas in the corresponding solvent was finally determined. Two different types of electrochemical sensors were used to prove the consistency of the method: one potentiometric and the other amperometric. The results obtained from both sensors would indicate that the method is consistent. In addition, we present an easy procedure for determining the partial pressure of the gas in the gas phase.

The electrochemical reduction of oxygen on glassy carbon (GC) electrodes modified with in situ generated diazonium cations of anthraquinone (AQ) has been studied using the rotating disk electrode (RDE) technique. The electrografting of the GC electrodes was carried out in two different media: in acetonitrile and in an aqueous acidic solution (0.5 M HCl). 1-and 2-Aminoanthraquinone were used as starting compounds for the formation of the corresponding diazonium derivatives. The anthraquinone diazonium cations were generated by reaction of the aminoanthraquinones with tert-butyl nitrite and sodium nitrite in acetonitrile and in 0.5 M HCl, respectively. For comparison purposes, the previously synthesised and crystallised diazonium tetrafluoroborates of anthraquinone were used for the GC surface modification. Cyclic voltammetry was employed to determine the surface concentration of AQ in O 2 free 0.1 M KOH. The electrocatalytic behaviour towards O 2 reduction was similar for all the AQ-modified electrodes studied. The kinetic parameters of oxygen reduction were determined using a surface redox catalytic cycle model. The rate constant of the reaction between the semiquinone radical anion of AQ and molecular oxygen was virtually independent of the point of attachment of the quinone to the electrode surface.

A cathodically pretreated boron-doped diamond electrode was used for the simultaneous anodic determination of ascorbic acid (AA) and caffeine (CAF) by differential pulse voltammetry. Linear calibration curves (r ¼ 0.999) were obtained from 1.9 Â 10 À5 to 2.1 Â 10 À4 mol L À1 for AA and from 9.7 Â 10 À6 to 1.1 Â 10 À4 mol L À1 for CAF, with detection limits of 19 mmol L À1 and 7.0 mmol L À1 , respectively. This method was successfully applied for the determination of AA and CAF in pharmaceutical formulations, with results equal to those obtained using a HPLC reference method.

We have obtained spinel-type Co 3 O 4 and La-doped Co 3 O 4 in the form of thin film on Ni, using microwave-assisted synthesis, which dramatically exhibit very low overpotentials for the oxygen evolution reaction (OER). Investigations have shown that at the apparent current density of 100 mA cm À2 in 1 mol dm À3 KOH at 25°C, the new electrodes, Co 3 O 4 (oxide loading = 3.4 ± 0.3 mg cm À2 ) and Ladoped Co 3 O 4 (oxide loading = 2.8 ± 0.4 mg cm À2 ), produce overpotentials, 235 ± 7 and 224 ± 8 mV, respectively. Such low overpotentials for the OER, to our knowledge, have not been found on any mixed oxide electrode material reported in literature till today. Small La addition improved the BET surface area and porosity of the oxide catalyst powder and reduced the charge transfer resistance for the OER on the electrode made of oxide powder.

Novel tungsten precursors, WH 2 (iPrCp) 2 and WH 2 (EtCp) 2 , with attractive thermal properties are introduced for Metal Organic Chemical Vapor Deposition (MOCVD) and Atomic Layer Deposition (ALD) of tungsten containing films. Their thermal behavior has been assessed using a vapor pressure measurement set-up and a thermal gravimetric apparatus (TG/DSC/DTA). Thin films of WC x and WN x C y were deposited depending on the reactant used. Kinetics of the surface reaction using WH 2 (iPrCp) 2 precursor has been evaluated carrying out MOCVD at low temperature ranging 350°C to 400°C. On-line QMS analysis of the deposition process was used to characterize the precursor decomposition pathway. Physical and electrical properties of the films were evaluated by X-Ray Reflectrometry (XRR), X-Ray Diffraction (XRD), X-Ray Photoelectron Spectroscopy (XPS), Secondary Ions Mass Spectrometry (SIMS), and four-point probe. Oxygen containing, porous and amorphous WC x (x ∼ 0.5) and WN x C y (x ∼ 0.4, y ∼ 0.2) thin films have been achieved.

Two aspects related to the deterioration process of organic coated structures under cathodic protection, detected in a previous work, are analysed: (i) why the size of failures exposing the metallic substrate can in¯uence the level of delamination and (ii) if there is a failure exposing the metallic substrate, why the appearance of blisters is fostered even away far from the original failure. The results show that an improvement of laboratory procedures for coatings selection can contribute to the development of coating/cathodic protection technology. Finally, the limitations of usual cathodic protection criteria are discussed considering the impedance measurements of samples with electrodes placed at the coating/metal interface.

A polymeric membrane-based ion-selective electrode (ISE) for the determination of l-ascorbic acid (l-AA) was developed. The sensor was fabricated by modifying glassy carbon electrodes with molecularly imprinted polypyrrole (PPy) synthesized by electropolymerization of the monomer in the presence of ascorbate. A comparison between the non-imprinted modified electrode (PPy-NIP) and the molecularly imprinted polymer (PPy-MIP) is reported. The molecularly imprinted polymer improves the performances of the sensor, especially if the PPy film has been submitted to an oxidation treatment. The PPy-MIPox electrode shows near-Nernstian response (approx. −57 mV/decade) to the ascorbate over the concentration range between 5 × 10 −6 M and 2 × 10 −3 M and it can be used for more than 3 weeks without any considerable change in the measured response. The potentiometric sensor has been successfully applied to the determination of ascorbate in food and pharmaceutical samples (recoveries of about 100%).

The voltammetric reduction of NiU(DMGH)2 complex preadsorbed on mercury both in 1 M NH4CI + NH 3 buffer and in 0.1 M borate buffer solutions was studied. In this work experimental evidence points to Nin(DMGH)2 reduction with simultaneous decomposition of the ligand DMGH-and reduction of Ni(II) to Ni(O). The experimental sweep rate dependence of peak current and potential is explained in terms of a ErC i surface reaction scheme and a rate expression that takes into account attractive forces between the adsorbed reactant complex.

A novel lithium salt, lithium (fluorosulfonyl)(nonafluorobutanesulfonyl)imide (LiFNFSI), is investigated as a conducting salt to improve the high-temperature resilience of lithium-ion cells. It shows better thermal stability than LiPF 6 . The electrolyte having 1.0 M LiFNFSI in a mixture of ethylene carbonate (EC)/ethyl methyl carbonate (EMC) (3:7, v/v) shows high conductivity comparable to LiClO 4 , good electrochemical stability, and does not corrode aluminum. At both room temperature (25°C) and elevated temperature (60°C), the graphite/LiCoO 2 cells with LiFNFSI exhibit better cycling performances than those with LiPF 6 . Particularly, at 60°C, the capacity fading rate of the LiFNFSI-based cell without any additive is 37% after 100 cycles, while the cell with LiPF 6 fails rapidly. These outstanding properties of LiFNFSI make it an attractive candidate to overcome the rapid capacity fading of lithium-ion batteries at elevated temperatures.

Phase holdups were measured in the riser section of a gas-liquid-solid circulating fluidized bed (GLSCFB). Electrical resistance tomography (ERT) as a non-invasive imaging technique, pressure transducers (PTs) and fibre optic probes were employed. Water was used as continuous and conductive phase, air as the gas phase and glass beads as solid nonconductive phases. ERT technique is based on conductivity measurement of the continuous phase (water in this study), which provides color-coded cross-sectional view of phases with a frequency of up to 250 images per second. The local conductivity measured by a number of electrodes located at the periphery of the plane was then further converted into a local phase concentration distribution based on Maxwell's relation. The results obtained by PTs, when combined with ERT results, were used to determine gas and solid holdups. Fibre optic probe was also employed to measure gas holdup independently. To measure gas and solid holdup, a model was introduced to exploit the fibre optic data in differentiating gas bubbles from solid particles in the riser. Radial profiles of the phase holdups were determined.

Sulfone-based electrolytes have been investigated as electrolytes for lithium-ion cells using high-voltage positive electrodes, such as LiMn 2 O 4 and LiNi 0.5 Mn 1.5 O 4 spinels, and Li 4 Ti 5 O 12 spinel as negative electrode. In the presence of imide salt (LiTFSI) and ethyl methyl sulfone or tetramethyl sulfone (TMS) electrolytes, the Li 4 Ti 5 O 12 /LiMn 2 O 4 cell exhibited a specific capacity of 80 mAh g À1 with an excellent capacity retention after 100 cycles. In a cell with high-voltage LiNi 0.5 Mn 1.5 O 4 positive electrode and 1 M LiPF 6 in TMS as electrolyte, the capacity reached 110 mAh g À1 at the C/12 rate. When TMS was blended with ethyl methyl carbonate, the Li 4 Ti 5 O 12 /LiNi 0.5 Mn 1.5 O 4 cell delivered an initial capacity of 80 mAh g À1 and cycled fairly well for 1000 cycles under 2C rate. The exceptional electrochemical stability of the sulfone electrolytes and their compatibility with the Li 4 Ti 5 O 12 safer and stable anode were the main reason behind the outstanding electrochemical performance observed with high-potential spinel cathode materials. These electrolytes could be promising alternative electrolytes for high-energy density battery applications such as plug-in hybrid and electric vehicles that require a long cycle life.

Los electrodos de grafito artificial son un estándar en la producción de acero en hornos eléctricos. El grafito artificial posee una alta conductividad eléctrica y elevada resistencia al choque térmico que lo hacen imprescindible para este uso. El consumo medio ha sido cuantificado, para un gran número de acerías eléctricas del grupo ArcelorMittal, en 1,43 kg/t [1]. La producción de acero crudo en acerías eléctricas fue en el año 2010 de 406 Mt. Podría estimarse el consumo de electrodos para hornos eléctricos en el orden de las 600.000 t/año; a esto se le debería sumar el consumo en los hornos cuchara. Entre los principales fabricantes están GrafTech International, SGL Group, Showa Denko Carbon, Tokai Carbon, HEG Ltd., Superior Graphite, UK CG, Beijing Fangda Carbon Tech, Chengdu Ronguang Carbon, Fangda Carbon New
Material, Fushun Carbon, Guangshan Shida Carbon, Hefei Carbon, GES (China), Jilin Carbon Import & Export. Es un mercado competitivo en costos, calidad y servicio, con estrategias diferenciadas y en el que ha habido en la última década un proceso importante de fusiones y adquisiciones. Una parte de las empresas mencionadas tiene sitios de producción en varios países. Se trata de una industria madura, que utiliza en general sistemas de producción modernos, con importante
grado de automatización, capaces de
formular electrodos con un alto grado de
repetitividad.
En el Cuadro 1 se presentan algunas fechas
importantes en el desarrollo y aplicación
de los electrodos de grafito [2].
Las materias primas para la producción
de los electrodos son el coque de petróleo,
preferentemente del tipo denominado
aguja y la brea de alquitrán de hulla.
Estos materiales se mezclan y procesan
a alta temperatura en varios pasos, hasta
obtener el grafito sintético. Es un producto
con un alto valor agregado energético.
En los párrafos siguientes se presentan
detalles sobre las materias primas utilizadas,
el proceso de fabricación, el diseño
de los electrodos y su aplicación, desde
el punto de vista de algunas de las novedades
tecnológicas que se han introducido
en las últimas décadas.
Cabe mencionar que los avances en las
materias primas, el proceso de fabricación
y la performance en uso son lentos.
El proceso de producción de los electrodos
es largo, de hasta dos meses; a esto
debe sumarse el tiempo de prueba en la
acería para saber si una cierta formulación
presenta ventajas, donde un gran
número de variables puede influir sobre
los resultados [4].

Despite decades of research, the study on tomography continues to be a subject of great scientific interest. Amongst all the kinds of tomography available, electrical resistance tomography (ERT) has been chosen as the field of study because of its advantages of being low cost, suitable for various kinds and sizes of pipes and vessels, having no radiation hazard, and being non-intrusive. In the development of ERT systems for conducting vessel walls, prior knowledge of the fundamental process of the ERT system whilst improving the design and operation of the process equipment is essential. In this paper, a review of the application of ERT for the conducting vessel wall is presented, providing information about its evolution over the years. The limitations and advantages of different strategies of ERT are also presented besides an overview of the system. Electrode fabrication on the conducting vessel wall is addressed.

Lithium-ion batteries (LIBs) are the current devices of choice for portable energy storage applications; however, improvements in energy and power densities are required to sustain future more demanding tasks, such as those associated with automotive transport. Commercially, LIB anodes are typically made from graphitic carbon-based systems that present bottlenecks associated with surface passivation and slow intercalation kinetics. We have investigated layered/graphitic carbon nitrides (gCNMs) as alternative anode materials; their unique structure and chemistry enable new intercalation processes not available for pure-C graphite. Our gCNMs are prepared from C, N-containing precursors treated at different temperatures. Cyclic voltammetry showed clear oxidation/reduction cycles in the 0.5-1.5 V range indicating that Li + intercalation took place resulting in electric conduction properties of the previously semiconducting material. Higher reaction temperatures lead to buckling of the graphitic layers and consequent loss of planarity, with a negative effect on their electrochemical performance.

Background: In contrast to the hyper-reactive platinum electrode, iodine-coated platinum electrode shows remarkable inertness toward adsorption and surface processes. For this reason, iodine-coated platinum electrode lends itself to interesting voltammetric applications. Hydrodynamic voltammetric analysis, one of the voltammetric techniques family, has many advantages over stationary voltammetric techniques inter aliathe steady state current and the higher sensitivity. Objective: The present work is aimed at utilization of iodine-coated platinum rotating disk electrode for analysis of iron in spinach.Methods: The developed method is based on a voltammetric sweep at an iodine-coated rotating-disk platinum electrode. The optimized experimental parameters included a potential scan from –0.20 to 0.85 V versus Ag/AgCl/[Cl-] = 1.0 M, 50 mV/s scan rate, and a rotation rate of 1000 rpm. Results: Oxidation of iron at the iodine-coated platinum rotating disk electrode was manifested by a wave...

This study offers an overview of the technologies for hydrogen production especially alkaline water electrolysis using solar energy. Solar Energy and Hydrogen (energy carrier) are possible replacement options for fossil fuel and its associated problems of availability and high prices which are devastating small, developing, oil-importing economies. But a major drawback to the full implementation of solar energy, in particular photovoltaic (PV), is the lowering of conversion efficiency of PV cells due to elevated cell temperatures while in operation. Also, hydrogen as an energy carrier must be produced in gaseous or liquid form before it can be used as fuel; but its‟ present major conversion process produces an abundance of carbon dioxide which is harming the environment through global warming. Alkaline water electrolysis is considered to be a basic technique for hydrogen production. In the present study, the effects of electrolyte concentration, solar insolation and space between the pair of electrodes on the amount of hydrogen produced and consequently on the overall electrolysis efficiency are experimentally investigated. The water electrolysis of potassium hydroxide aqueous solution was conducted under atmospheric pressure using stainless steel 316 as electrodes.The experimental results showed that the performance of alkaline water electrolysis unit is dominated by operational parameters like the electrolyte concentration and the gap between the electrodes. Smaller gaps between the pair of electrodes and was demonstrated to produce higher rates of hydrogen at higher system efficiency. This study shows some attempts to product pure Hydrogen and pure Oxygen as both Hydrogen and Oxygen have there commercial demands.

Capacitive deionization (CDI) has attracted the interest of the community investigating water treatment technologies since the mid-1960s. The technology is based on the recognition that high-surface-area electrodes, when electrically charged, can quantitatively adsorb ionic components from water, thereby resulting in desalination. The article reviews the theoretical and technological background of CDI, the history of its development, and past and present attempts towards scaling up and commercialization. It also provides a critical review of the advantages and limitations of the technology. In addition, further research approaches necessary to render CDI a mature and competitive technology for the treatment of brackish and surface waters are outlined.

Despite its success for modeling electrolyte thermodynamics in aqueous media, the use of the Pitzer approach for the investigation of electrolytes in nonaqueous or in mixed solvent media is still very limited. Further, a review of the literature reveals that there are no more than a few research groups who have used the exact form of the Pitzer-Simonson-Clegg (PSC) ion-interaction approach for the investigation of electrolytes in mixed solvent systems. As a continuation of our previous studies, the present investigation reports modeling of HCl in the 2-propanol + water mixed solvent system with the Pitzer, PSC and an extended form of the PSC ion-interaction approaches using the experimental potentiometric data from a cell containing pH glass membrane and Ag/AgCl electrodes. The electrochemical measurements were performed over the HCl molality range from 0.01 to 4.5 mol·kg −1 in mixed 2-propanol (x%) + water (100 − x%) solvents, with different solvent percent mass fractions (x% = 10, 20, 30, 40 and 50%) at 298.15 ± 0.05 K.

Electrical resistance tomography (ERT), which is a non-invasive and robust measurement technique, was employed to visualize, in three dimensions, the concentration field inside a cylindrical mixing vessel equipped with a radial-flow Scaba 6SRGT impeller. The ability of ERT to work in opaque fluids makes this technique very attractive from an industrial perspective. An ERT system with a 4-plane assembly of peripheral sensing rings, each containing 16 electrodes, was used to measure the mixing time in agitation of xanthan gum solution which is a pseudoplastic fluid with yield stress. An image reconstruction algorithm was used to generate images of the tracer distribution within the sensing zone. In this study, the effect of impeller speed, fluid rheology, power consumption, and Reynolds number on the mixing time was investigated.

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