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PubMed1988

Ultrastructural changes in dermal pig skin after exposure to heat and electric energy and acid and basic solutions.

In order to describe the ultrastructure of the histopathological changes in dermis after exposure to electrical energy, heat energy and acid and basic solutions the skin of fully anaesthetized Danish Landrace pigs were exposed to direct current, heat (80 degrees C and 450 degrees C) and acid and basic solutions. Biopsies were obtained immediately after the exposure from all types of injury. Biopsies from the cathode areas biopsies were also taken on day 1 and day 2.5 in order to describe the initial calcium deposits. Homogeneous collagen fibres without any birefringence from heat exposed areas were ultrastructurally composed of filamentous materials. Collagen fibres with fine densely spaced cross-striation from cathode areas and areas exposed to basic solutions were shown ultrastructurally to consist of parallelly arranged collagen fibrils with regular waves. It is concluded that the cross-striation of the collagen fibres observed in polarized light are due to a periodic change in the orientation of the fibres seen as waves of the fibres. The ultrastructure of dermal cells were similar to that of epidermal cells following the different types of influence. Characteristically the nuclei were condensed following heat and more electron-lucent following direct current (d.c.) and acid and basic solutions. In cathode areas and areas influenced by basic solutions the electron-lucent nuclei contained fine fibrils. The ultrastructural study supports the suggestion from light microscopic studies that the morphology of anode and cathode lesions shows resemblance to acid induced and basic induced lesions, respectively. Apatite crystals were observed on day 2.5 at the periphery of the collagen fibrils and in the matrix of elastic fibres.

Animals↗
PubMed2005

Simultaneous removal of organic compounds and heavy metals from soils by electrokinetic remediation with a modified cyclodextrin.

Thousands of sites are contaminated with both heavy metals and organic compounds and these sites pose a major threat to public health and the environment. Previous studies have shown that electrokinetic remediation has potential to remove heavy metals and organic compounds when they exist individually in low permeability soils. This paper presents the feasibility of using cyclodextrins in electrokinetic remediation for the simultaneous removal of heavy metals and polycyclic aromatic hydrocarbons (PAHs) from low permeability soils. Kaolin was selected as a model low permeability soil and it was spiked with phenanthrene as well as nickel at concentrations of 500 mg kg-1 each to simulate typical mixed field contamination. Bench-scale electrokinetic experiments were conducted using hydroxypropyl beta-cyclodextrin (HPCD) at low (1%) and high (10%) concentrations and using deionized water in control test. A periodic voltage gradient of 2VDC cm-1 (with 5 d on and 2 d off) was applied to all the tests, and 0.01 M NaOH was added during the experiments to maintain neutral pH conditions at anode. In all tests, nickel migrated as Ni2+ ions towards the cathode and most of it was precipitated as Ni(OH)2 within the soil close to the cathode due to high pH condition generated by electrolysis reaction. The solubility of phenanthrene in the flushing solution and the amount of electroosmotic flow controlled the migration and removal of phenanthrene in all the tests. Even though high flow was generated in tests using deionized water and 1% HPCD, migration and removal of phenanthrene was low due to low solubility of phenanthrene in these solutions. The test with 10% HPCD solution showed higher solubility of phenanthrene which caused it migrate towards the cathode, but further migration and removal was retarded due to reduced electric current and electroosmotic flow. Approximately one pore volume of flushing resulted in approximately 50% removal of phenanthrene from the soil near the anode. Sustained higher electroosmotic flow with higher concentration cyclodextrin and maintaining low soil pH near cathode should be investigated to increase removal efficiency of both phenanthrene and nickel.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed2005

Influences of pH and current on electrolytic dechlorination of trichloroethylene at a granular-graphite packed electrode.

Electrolytic dechlorination using a granular-graphite packed cathode is an alternative method for the remediation of chlorinated organic compounds. Its effectiveness under various conditions needs experimental investigation. Dechlorination of trichloroethylene (TCE) was conducted under various conditions in an electrolytic reactor with a platinum-gauze anode and a granular-graphite packed cathode. The higher the applied current, the more TCE was eliminated and more hydrogen and oxygen gasses were generated. Current efficiency decreased with a decrease in TCE concentration during each dechlorination experiment. But, the current efficiency concentration coefficient (CECC), which was defined as current efficiency divided by concentration, was a better indicator of current efficiency. The CECC was not significantly affected by current, but it varied with pH value. The pH effects were results of the involvement of electrolytes in the proton reduction and the electron transfer at the cathode. A lower pH value favored TCE dechlorination in potassium chloride, which is an electrolyte that was not involved in cathode reactions with protons and electrons. In ammonium acetate and potassium nitrate, which involve proton reduction and/or electron transfer, the pH value affected TCE dechlorination through proton limitation and electron competition.

Electrodes↗
PubMed2006

Palladium-facilitated electrolytic dechlorination of 2-chlorobiphenyl using a granular-graphite electrode.

Palladium-assisted electrocatalytic dechlorination of 2-chlorobiphenyl (2-Cl BP) in aqueous solutions was conducted in a membrane-separated electrochemical reactor with granular-graphite packed electrodes. The dechlorination took place at a granular-graphite cathode while Pd was electro-deposited from the K2PdCl6 in the solution and at a Pd-deposited granular-graphite electrode. Using the Pd-deposited graphite cathode in the membrane reactor for a sequence of experiments, each was conducted under a lower current than in the previous one, and the rate of dechlorination became slower in each consecutive experiment. At the end of this sequence, a duplicate experiment showed a loss of activity of the Pd-deposited granular-graphite cathode. In the experiments of dechlorination while Pd was deposited at the granular-graphite electrode, the rate of dechlorination increased with increases of the initial K2PdCl6 concentration and of the applied cathode potential. In each experiment, the dechlorination of 2-Cl BP was relatively fast at the beginning, as demonstrated in an experiment in which 66.4% of 2-Cl BP was dechlorinated within 4h, but the rate of dechlorination decreased over the time. This decrease can be described with two stages of exponential decrease. The values of the rate constant in the first stage varies with the applied potential and the initial K2PdCl6 concentration, but the values of the rate constant in the second stage do not show any dependence on the potential and the K2PdCl6 concentration. The current efficiency of dechlorination was improved by applying part-time current to the electrodes.

Biphenyl Compounds↗
PubMed2006

Epidural cortical stimulation enhances motor function after sensorimotor cortical infarcts in rats.

This study examined whether epidurally delivered cortical electrical stimulation (CS) improves the efficacy of motor rehabilitative training and alters neuronal density and/or cell proliferation in perilesion cortex following ischemic sensorimotor cortex (SMC) lesions. Adult rats were pre-trained on a skilled reaching task and then received partial unilateral SMC lesions and implantation of electrodes over the remaining SMC. Ten to fourteen days later, rats received daily reach training concurrent with anodal or cathodal 100 Hz CS or no stimulation (NoCS) for 18 days. To label newly generated cells, bromodeoxyuridine (BrdU; 50 mg/kg) was administered every third day of training. Both anodal and cathodal CS robustly enhanced reaching performance compared to NoCS controls. Neuronal density in the perilesion cortex was significantly increased in the cathodal CS group compared to the NoCS group. There were no significant group differences in BrdU-labeled cell density in ipsilesional cortex. Staining with Fluoro-Jade-B indicated that neurons continue to degenerate near the infarct at the time when cortical stimulation and rehabilitation were initiated. These data indicate that epidurally delivered CS greatly improves the efficacy of rehabilitative reach training following SMC damage and raise the possibility that cathodal CS may influence neuronal survival in perilesion cortex.

Analysis of Variance↗
PubMed2005

Reduction of nitrobenzene by the catalyzed Fe-Cu process.

The electrochemical reduction characteristics of nitrobenzene were investigated using cyclic voltammetry. In addition, the difference in reduction mechanisms between Master Builders' iron and the catalyzed Fe-Cu process was discussed in this paper. The results showed that nitrobenzene was reduced directly on the surface of copper rather than by the hydrogen evolved at cathode in the catalyzed Fe-Cu process. The reduction was realized largely by the hydrogen evolved at cathode in Master Builders' iron. Both acidity and basicity favored the direct reduction at the copper electrode. The catalyzed Fe-Cu process was superior to Master Builders' iron in treating nitrobenzene-containing water, withal. This advantage was particular noticeable under alkaline conditions. The reduction was investigated in the cathode and anode compartments, respectively, and the experimental results showed that the direct pathway had a large role in the reduction by the catalyzed Fe-Cu process. To reduce nitrobenzene directly at the copper electrode is easier than to reduce it by the hydrogen evolved at cathode, copper could be regarded as the electrocatalyst in this case. The influence of copper usage on the treatment efficiency by the catalyzed Fe-Cu process was also studied. The results indicated copper increased the reduction rate. The catalyzed Fe-Cu process is of practical value.

Catalysis↗
PubMed2004

Potential of galvanotaxis to separation and cleaning of rumen ciliates.

The ability of rumen ciliate protozoa to move in a unidirectional electrical field from the anode to the cathode was tested in large-volume electromigration equipment; the aim was to concentrate the microorganisms and clean them of impurities. During galvanotaxis in the freshly harvested rumen fluid and at a voltage of 10 V (I=0.8 mA), cells of Isotricha (Isotricha prostoma, Isotricha intestinalis) were the first to swim towards the cathode; 1 min later, they were followed by Dasytricha ruminantium. Entodiniomorphous ciliates (small Entodiniae as well as large species) displayed minimum movement towards the cathode. The yield of electromigration of Entodinium caudatum from the in vitro culture ranged within 2-6% when using 75-100 V (10 mA) and 60 V (5 mA) voltage, respectively. At 10 V (0.8 mA), E. caudatum did not move towards the cathode. It is shown that the behavior of Trichostomatids (Dasytricha and Isotricha) facilitates separation by means of the tested large-volume equipment. Concentration and cleaning of Entodiniomorphous ciliates using galvanotaxis in the tested equipment proved to be ineffective.

Animals↗
PubMed2006

Embryonic zebrafish neuronal growth is not affected by an applied electric field in vitro.

Naturally occurring electric fields (EFs) have been implicated in cell guidance during embryonic development and adult wound healing. Embryonic Xenopus laevis neurons sprout preferentially towards the cathode, turn towards the cathode, and migrate faster towards the cathode in the presence of an external EF in vitro. A recent Phase 1 clinical trial has investigated the effects of oscillating EFs on human spinal cord regeneration. The purpose of this study was to investigate whether embryonic zebrafish neurons respond to an applied EF, and thus extend this research into another vertebrate system. Neural tubes of zebrafish embryos (16-17 somites) were dissected and dissociated neuroblasts were plated onto laminin-coated glass. A 100 mV/mm EF was applied to cell cultures for 4 or 20 h and the responses of neurons to the applied EFs were investigated. After 4h in an EF neurites were significantly shorter than control neurites. No other statistically significant effects were observed. After 20 h, control and EF-exposed neurites were no different in length. No length difference was seen between cathodally- and anodally-sprouted neurites. Application of an EF did not affect the average number of neurons in a chamber. Growth cones did not migrate preferentially towards either pole of the EF and no asymmetry was seen in neurite sprout sites. We conclude that zebrafish neurons do not respond to a 100 mV/mm applied EF in vitro. This suggests that neurons of other vertebrate species may not respond to applied EFs in the same ways as Xenopus laevis neurons.

Animals↗
PubMed2005

Characterization of spent AA household alkaline batteries.

The aim of this work is identification of the structural components of actual domestic spent alkaline AA batteries, as well as quantification of some of their characteristics. Weight, humidity, ash content, zinc and zinc oxide on anode, manganese on cathode and other metals, potassium hydroxide on the internal components and heating values for papers, anode and cathode were determined in several batteries. As expected, cathode, anode and the steel can container are the main contributors to the 23.5 g average weight of the batteries. Cathode is also the major contributor to the positive heating value of the batteries as well as to the heavy metals content. Mercury was detected in very low levels in these mercury-free batteries. Zinc and zinc oxide amounts in the anodes are highly variable. Results obtained were compared to information on alkaline batteries in the literature from 1993 to 1995; and a positive evolution in their manufacture is readily apparent. Data from the producer of batteries shows some small discrepancies relative to the results of this experimental work.

Arsenic↗
PubMed2006

Development of a continuous electrolytic system with discharging only one pH-controlled stream and its characteristics.

In order to produce only a pH-controlled solution without discharging any unused solution, this work has developed a continuous electrolytic system with an ion exchange membrane-equipped electrolyzer and a tank, called as a pH-adjustment reservoir, placed just in front of the electrolyzer, where as a target solution was fed into the pH-adjustment reservoir, a portion of the solution in the pH-adjustment reservoir was circulated through the cathodic or anodic chamber of the electrolyzer depending on the type of the ion exchange membrane used, and another portion of the solution in the pH-adjustment reservoir was discharged from the electrolytic system through the opposite electrode chamber with its pH being controlled. The internal circulation of the pH-adjustment reservoir solution through the anodic chamber in the case of using a cation exchange membrane and that through the cathodic chamber in the case of using an anion exchange membrane could make the solution, discharged from the other counter chamber, effectively acidic and basic, respectively. The phenomena of the pH being controlled in the system could be explained by the electro-migration of the ion species in the solution through the ion exchange membrane under a cell potential difference between the anode and the cathode and its consequently-occurring non-charge equilibriums and the electrolytic water-split reactions in the anodic and cathodic chambers.

Chemical Industry↗
PubMed1981

The role of electro-osmosis in the electric-field-induced movement of charged macromolecules on the surfaces of cells.

The surfaces of most cells bear a net negative charge. The imposition of an electric field parallel to the surface of the cell should produce, therefore, an electro-osmotic flow of fluid towards the cathodal side of the cell. Our analysis of a simple model of the cell surface indicates that a negatively charged mobile macromolecule will be swept by this electro-osmotic flow of fluid to the cathodal side of the cell if its zeta potential, zeta 1, is less negative than the zeta potential of the cell surface, zeta 2. Conversely, if zeta 2 is less negative than zeta 1, the negatively charged macromolecule will accumulate at the anodal side of the cell. Our experimental results demonstrate that concanavalin A (Con A) receptors on embryonic muscle cells normally accumulate at the cathodal side of the cell, but that they can be induced to accumulate at the anodal side of the cell by preincubating the myotubes either with neuraminidase, a treatment that removes negatively charged sialic acid residues, or with the lipid diI, a treatment that adds positive charges to the surface of the cell. Addition of the negatively charged lipid monosialoganglioside (GM1), on the other hand, enhances the accumulation of Con A receptors at the cathodal side of the cell.

Animals↗
PubMed1995

Spatial distribution of cardiac transmembrane potentials around an extracellular electrode: dependence on fiber orientation.

Recent theoretical models of cardiac electrical stimulation or defibrillation predict a complex spatial pattern of transmembrane potential (Vm) around a stimulating electrode, resulting from the formation of virtual electrodes of reversed polarity. The pattern of membrane polarization has been attributed to the anisotropic structure of the tissue. To verify such model predictions experimentally, an optical technique using a fluorescent voltage-sensitive dye was used to map the spatial distribution of Vm around a 150-microns-radius extracellular unipolar electrode. An S1-S2 stimulation protocol was used, and vm was measured during an S2 pulse having an intensity equal to 10x the cathodal diastolic threshold of excitation. The recordings were obtained on the endocardial surface of bullfrog atrium in directions parallel and perpendicular to the cardiac fibers. In the longitudinal fiber direction, the membrane depolarized for cathodal pulses (and hyperpolarized for anodal pulses) but only in a region within 445 +/- 112 microns (and 616 +/- 78 microns for anodal pulses) from the center of the electrode (n = 9). Outside this region, vm reversed polarity and reached a local maximum at 922 +/- 136 microns (and 988 +/- 117 microns for anodal pulses) (n = 9). Beyond this point vm decayed to zero over a distance of 1.5-2 mm. In the transverse fiber direction, the membrane depolarized for cathodal pulses (and hyperpolarized for anodal pulses) at all distances from the electrode. The amplitude of the response decreased with distance from the electrode with an exponential decay constant of 343 +/- 110 microns for cathodal pulses and 253 +/- 91 microns for anodal pulses (n = 7). The results were qualitatively similar in both fiber directions when the atrium was bathed in a solution containing ionic channel blockers. A two-dimensional computer model was formulated for the case of highly anisotropic cardiac tissue and qualitatively accounts for nearly all the observed spatial and temporal behavior of vm in the two fiber directions. The relationships between vm and both the "activating function" and extracellular potential gradient are discussed.

Animals↗
PubMed1980

Arylesterase isoenzymes and activity in normal healthy adults and in patients with cancer and with other diseases.

Serum arylesterase isozyme patterns were studied in 184 normal healthy individuals, 290 cancer patients and 466 patients with various diseases. No abnormal patterns were seen in the normal healthy subjects. Several abnormal patterns found in the group of cancer patients and patients with various diseases are described. In the majority of patients with cancer of the liver there is an abnormal additional cathodal band. The most cathodal band in normals or the two most cathodal bands in the patients with hepatoma with double cathodal bands stained for cholinesterase as well as for arylesterase. We also studied serum arylesterase activity on the basis of the kinetic release of beta-naphthol in these groups. The mean activity in normal healthy individuals agrees with that reported earlier. In patients with cancer and with miscellaneous other diseases, the mean activity is lower but the range of values in the two groups is very wide.

Adult↗
PubMed2003

Nonspecific vasodilatation during transdermal iontophoresis-the effect of voltage over the skin.

We used laser Doppler perfusion imaging (LDPI) to study nonspecific vasodilatation during iontophoresis. In iontophoresis studies, nonspecific vasodilatation occurs as a result either of galvanic currents or of the applied voltage over the skin. We made dose-response measurements to study the effect of ionic strength of the vehicle on the nonspecific vasodilatation during iontophoresis of sodium chloride and deionized water, while we monitored the voltage over the skin. We found that anodal and cathodal ionotophoresis induced a voltage over the skin that was dependent on the ionic strength of the test solution. The nonspecific vasodilatation during anodal iontophoresis was less pronounced than during cathodal iontophoresis, and was independent of the voltage over the skin. The nonspecific vasodilatation in cathodal iontophoresis was related to the voltage over the skin, and was possibly mediated by depolarization of local sensory nerves. In experiments using cathodal iontophoresis, therefore, the ionic strengths of the vehicle and the drug are important when vasoactive drugs are examined, as the nonspecific vasodilatation needs to be controlled for. As the vasodilatation that we observed was heterogeneously distributed within the area of iontophoresis, LDPI may provide more accurate measurements than conventional laser Doppler perfusion monitoring.

Administration, Cutaneous↗
PubMed2001

Removal of organic pollutants from industrial wastewater by electrogenerated Fenton's reagent.

This study was performed to investigate the treatment of an industrial wastewater mainly containing naphthalene- and anthraquinone-sulphonic acids, by electrogenerated Fenton's reagent. The hydrogen peroxide was produced in situ by electrochemical reduction of oxygen on graphite-felt cathodes and the Fe2+ ions were also regenerated by cathodic reduction of Fe3+. The influence of cathode potential, Fe2+ concentration and electrode surface pre-treatment on chemical oxygen demand (COD) removal and colour fading were studied. Results indicated that the higher COD removal was obtained in the presence of 3 mM of ferrous ions working at a constant potential of -1 V vs. SCE. Moreover, it was shown that both chemical and electrochemical pre-treatments of the cathode surface resulted in a decrease of COD depletion.

Anthraquinones↗
PubMed2001

Electrochemical treatment of acidic aqueous ferrous sulfate and copper sulfate as models for acid mine drainage.

Acid mine drainage (AMD) is a serious environmental problem in the mining industry. The present work describes electrolytic reduction of solutions of synthetic AMD, comprising FeSO4/H2SO4 and CuSO4/H2SO4, in flow-through cells whose anode and cathode compartments were separated using ion exchange membranes. In the case of FeSO4/H2SO4 at constant flow rate, the pH of the effluent from the catholyte increased progressively with current at a variety of cathodes, due to electrolytic reduction of H+ ions to elemental hydrogen. Near-quantitative removal of iron was achieved by sparging air into the catholyte effluent, thereby precipitating iron outside the electrochemical cell, and avoiding fouling of the electrodes. The anode reaction was the oxidation of water to O2, a proton-releasing process. Using cation exchange membranes and sodium sulfate as the supporting electrolyte in the anode compartment, the efficiency of the process was compromised at high currents by transport of H+ competitively with Na+ from the anode to the cathode compartments. Higher efficiencies were obtained when anion exchange membranes were used, and in this case no additional supporting electrolyte other than dilute H2SO4 was needed, the net reaction being the electrochemically driven transfer of the elements of H2SO4 from the cathode to the anode compartments. Current efficiencies approximately 50% were achieved, the loss of efficiency being accounted for by ohmic heating of the solutions. In the case of CuSO4/H2SO4 and anion exchange membranes at high currents, reduction of Cu2+ and H+ ions and transport of SO4(2-) ions out of the catholyte caused unacceptably high potentials to be generated.

Cations↗
PubMed2002

Electrochemical generation of hydrogen peroxide from dissolved oxygen in acidic solutions.

Hydrogen peroxide (H2O2) was electro-generated in a parallel-plate electrolyzer by reduction of dissolved oxygen (DO) in acidic solutions containing dilute supporting electrolyte. Operational parameters such as cathodic potential, oxygen purity and mass flow rate, cathode surface area. pH, temperature, and inert supporting electrolyte concentration were systematically investigated as to improve the Faradic current efficiency of H2O2 generation. Results indicate that significant self-decomposition of H2O2 only occurs at high pH (> 9) and elevated temperatures (> 23 degrees C). Results also indicate that the optimal conditions for H2O2 generation are cathodic potential of -0.5 V vs. saturated calomel electrode (SCE), oxygen mass flow rate of 8.2 x 10(-2) mol/min, and pH 2. Under the optimal conditions, the average current density and average current efficiency are 6.4A/m2 and 81%, respectively. However, when air is applied at the optimal flow rate of oxygen, the average current density markedly decreases to 2.1 A/m2, while the average current efficiency slightly increases to 90%. The limiting current density is 6.4 A/m2, which is independent of cathode geometry and surface area. H2O2 generation is favored at low temperatures. In the concentration range studied (0.01-0.25 M), the inert supporting electrolyte (NaClO4) affects the total potential drop of the electrolyzer, but does not affect the net generation rate of H2O2.

Acids↗
PubMed2002

Laboratory study of electro-coagulation-flotation for water treatment.

An electro-coagulation-flotation process has been developed for water treatment. This involved an electrolytic reactor with aluminium electrodes and a separation/flotation tank. The water to be treated passed through the reactor and was subjected to coagulation/flotation, by Al(III) ions dissolved from the electrodes, the resulting flocs floating after being captured by hydrogen gas bubbles generated at cathode surfaces. Apparent current efficiencies for Al dissolution as aqueous Al(III) species at pH 6.5 and 7.8 were greater than unity. This was due to additional reactions occurring in parallel with Al dissolution: oxygen reduction at anodes and cathodes, and hydrogen evolution at cathodes, resulting in net (i.e. oxidation + reduction) currents at both anodes and cathodes. The specific electrical energy consumption of the reactor for drinking water treatment was as low as 20 kWh (kg Al)(-1) for current densities of 10-20A m(-2). The water treatment performance of the electrocoagulation process was found to be superior to that of conventional coagulation with aluminium sulphate for treating a model-coloured water, with 20% more dissolved organic carbon (DOC) being removed for the same Al(III) dose. However, for a lowland surface water sample, the two processes achieved a similar performance for DOC and UV-absorbance removal. In addition, an up-flow electrocoagulator configuration performed better than a horizontal flow configuration, with both bipolar and monopolar electrodes.

Alum Compounds↗