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Electrodes Used (electrode + used)
Selected AbstractsDifferential Pulse Voltammetric Determination of Selected Nitro-Compounds on Silver, Solid Silver Composite, and Solid Graphite Composite ElectrodesELECTROANALYSIS, Issue 3-5 2009Navrátil Abstract Three different types of solid electrodes, namely silver electrode, silver composite electrode containing 20% (m/m) of silver powder, 20% (m/m) of graphite powder and 60% (m/m) of methacrylate resin and graphite composite electrode containing 30% (m/m) of graphite powder and 70% (m/m) of epoxy resin were tested for differential pulse voltammetric determination of selected genotoxic nitro-compounds using 2-nitronaphthalene, 6-nitroquinoline, and 5-nitrobenzimidazole as model compounds. It was found that all three electrodes can be used for the determination of micromolar concentrations of tested model substances, the limit of detection and other figures of merits being dependent both on the electrode used and the substance to be determined. [source] Catalytic Effect on Silver Electrodeposition of Gold Deposited on Carbon ElectrodesELECTROANALYSIS, Issue 19 2004Alfredo de, Escosura-Muńiz Abstract A new methodology, based on silver electrocatalytic deposition and designed to quantify gold deposited onto carbon paste electrode (CPE) and glassy carbon electrode (GCE), has been developed in this work. Silver (prepared in 1.0,M NH3) electrodeposition at ,0.13,V occurs only when gold is previously deposited at an adequate potential on the electrode surface for a fixed period of time. When a CPE is used as working electrode, an adequate oxidation of gold is necessary. This oxidation is carried out in both 0.1,M NaOH and 0.1,M H2SO4 at oxidation potentials. When a GCE is used as working electrode, the oxidation steps are not necessary. Moreover, a cleaning step in KCN, which removes gold from electrode surface, is included. To obtain reproducibility in the analytical signal, the surface of the electrodes must be suitably pretreated; this electrodic pretreatment depends on the kind of electrode used as working electrode. Low detection limits (5.0×10,10,M) for short gold deposition times (10,min for CPE and 5,min for GCE) were achieved with this novel methodology. Finally, sodium aurothiomalate can be quantified using silver electrocatalytic deposition and GCE as working electrode. Good linear relationship between silver anodic stripping peak and aurothiomalate concentration was found from 5.0×10,10,M to 1.0×10,8,M. [source] Shift of oxidants and antioxidants levels in rats as a reaction to exposure to sulfur mustardJOURNAL OF APPLIED TOXICOLOGY, Issue 8 2009Miroslav Pohanka Abstract Antixodants as well as oxidants levels were investigated in plasma of rats exposed to sulfur mustard in doses of 0 (control), 5, 20 and 80 mg kg,1 body weight. Cyclic voltammetry performed on screen-printed strips with platinum working electrode used as a tool for assaying oxidant and antioxidant levels. We found significant shifts in both examined analytes. A dose of sulfur mustard of 5 mg kg,1 body weight caused only a small change in oxidant and antioxidant levels when compared with the control group. A dose of 20 mg kg,1 body weight provided a significant increase in antioxidants as well oxidants; however, the ratio of both was similar to that in the control group. The most surprising facts were found when the highest dose of 80 mg kg,1 body weight of sulfur mustard was applied. While antioxidants were significantly increased, oxidants were decreased on an extensive scale. Copyright © 2009 John Wiley & Sons, Ltd. [source] Improved Plasma Spray Torch Stability Through Multi-Electrode DesignCONTRIBUTIONS TO PLASMA PHYSICS, Issue 7 2007J. Schein Abstract Coating production by thermal plasma spray is dependent on the residence time of particles in the plasma jet produced by the gas flow inside a plasma torch. To ensure a high fraction of well-molten particles to be accelerated towards the substrate a long reproducible residence time is needed. This can be achieved by a long plasma jet with little or no temporal variation in length and temperature. While single electrode plasma torches need an unstable attachment of the anodic arc root in order to avoid excess erosion, which also causes an unstable plasma jet, multi-electrode torches allow operation with fixed anode attachments by subdividing the anode current by the number of electrodes used, and thereby thus reducing the power input for each separated arc root. Once the steady anode attachment has been obtained the produced plasma jet exhibits a steady characteristic, but also looses rotational symmetry. The separation can be achieved by using either multi anode or multi cathode geometry with appropriate electrical control. Both version have been produced with 3 electrodes each resulting in two systems known as the Delta Gun (3 anodes) and Triplex (3 cathodes). (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Topographic electroencephalogram in children during mask induction of anaesthesia with sevofluraneACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2009E. SONKAJÄRVI Background: Epileptiform patterns, spikes, polyspikes and periodic epileptiform discharges (PED) have been reported in electroencephalograms (EEGs) during anaesthesia induction with sevoflurane in healthy adults and children. Published recordings have been performed with a limited number of channels, and therefore the topographic distributions of these patterns are not known. Methods: Twenty ASA I children aged 4,10 years undergoing routine operations were anaesthetized with 8% sevoflurane in 50%/50% oxygen and nitrous oxide using mask induction with controlled normoventilation. An EEG was recorded with a full 10,20 electrode system including orbitofrontal and ear electrodes, and a recording band of 0.016,70 Hz. Beat-to-beat heart rate (HR) was calculated off-line. Results: Nineteen out of 20 children developed multifocal spikes and polyspikes with a maximum over the frontal lobes. Four patients developed suppression, which was almost continuous and lasted several minutes, and thereafter a continuous EEG resumed, a few spikes were seen and then a nonepileptiform pattern. In three children a couple of PED waves were seen at the onset of a continuous EEG. HR increased maximally before the onset of spikes. No motor phenomena were seen. Conclusion: These recordings confirm the epileptogenic property of sevoflurane in mask induction. The spikes and polyspikes had frontal multifocal maxima and may be missed in recordings from frontopolar electrodes used by depth-of-anaesthesia monitors. PED and burst suppression were synchronous over the whole cortex. Epileptiform activity was indiscernible from epileptiform waveforms without anaesthesia, such as the patterns seen in status epilepticus. [source] Is the target for thalamic deep brain stimulation the same as for thalamotomy?MOVEMENT DISORDERS, Issue 10 2003FRCSC, Zelma H.T. Kiss MD Abstract Deep brain stimulation (DBS) has virtually replaced thalamotomy for the treatment of essential tremor. It is thought that the site for DBS is the same as the optimal lesion site; however, this match has not been investigated previously. We sought to determine whether the location of thalamic DBS matched the site at which thalamotomy would be performed. Eleven patients who had detailed microelectrode recording and stimulation for placement of DBS electrodes and subsequent successful tremor control were analysed. An experienced surgeon, blinded to outcome and final electrode position, selected the ideal thalamotomy site based on the reconstructed maps obtained intraoperatively. When the site of long-term clinically used DBS and theoretical thalamotomy location was calculated in three-dimensional space and compared for each of the x, y, and z axes in stereotactic space, there was no significant difference in the mediolateral location of DBS and theoretical lesion site. There was also no difference between the theoretical lesion site and the placement of the tip of the electrode; however, the active electrodes used for chronic stimulation were significantly more anterior (P = 0.005) and dorsal (P = 0.034) to the ideal thalamotomy target. This mismatch may reflect the compromise required between adverse and beneficial effects with chronic stimulation, but it also suggests different mechanisms of effect of DBS and thalamotomy. © 2003 Movement Disorder Society [source] Intraoperative Study of Polarization and Evoked Response Signals in Different Endocardial Electrode DesignsPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 7 2001CHING LAU LAU, C., et al.: Intraoperative Study of Polarization and Evoked Response Signals in Different Endocardial Electrode Designs. Some new generation pacemakers use an algorithm based on evoked response (ER) detection to verify beat-to-beat capture and to enable automatic adjustment of output. This is a prospective acute study of polarization signal (PS) and ER in nine currently available electrodes. Intraoperative testing of ventricular bipolar electrodes used the Autocapture (AC) algorithm. The intrinsic R wave, PS, ER, acceptance of AC function, and stimulation thresholds (STs) were obtained. Ventricular electrodes were categorized as follows: titanium nitride (TiN)-coated passive and active fixation, high impedance (HI), passive fixation (VP), iridium oxide-coated titanium (IROX) (VI), and platinum helix (PH) active fixation. Acute testing was performed in 217 patients with an average age of 74.26 years, 59.6% were men with primary pacing indication-SSS (46.3%). There were no significant differences found with respect to R wave and threshold between the various electrodes. PH active-fixation electrodes had significantly higher ER and PS than other groups including the TiN-coated active-fixation electrodes. TiNcoated electrodes (active and passive fixation) had significantly lower PS than other electrodes. As a result, TiN electrodes had a significantly higher functional rate of AC (91.7%), whereas PH had the lowest rate (0%). In conclusion, (1) polarization characteristics are significantly different for commercially available ventricular electrodes, (2) certain physical features at the tissue to electrode interface like TiN coating appears to be more important in determining PS than electrode tip size and fixation method, and (3) the current algorithm for AC requires electrodes that provide low polarization for satisfactory performance. [source] Electrical Taste Thresholds Established on the Medial Tongue using Two Sizes of Electrodes,THE LARYNGOSCOPE, Issue 8 2005Serban A. Nicolaescu BS Abstract Objectives/Hypothesis: The present study determined whether a 125 mm2 electrode would produce lower and more reliable electrical taste thresholds than a 25 mm2 electrode when measurement occurred in a medial tongue region relatively sparse in taste bud numbers. We hypothesized this would be the case and that the obtained threshold values would be higher than those previously reported for anterior and lateral tongue regions. Study Design And Methods: Sixteen college-age subjects were tested twice, once using the 25 mm2 electrode and once using the 125 mm2 electrode on each of two sessions separated by 2 to 16 days. The order of presentation of the sessions was counterbalanced across subjects. Measurement was confined to the medial tongue, 0.7 cm lateral to the median furrow. Results: As hypothesized, the larger electrode resulted in lower and more reliable threshold values than the smaller electrode (respective median threshold values = 20.06 ,A & 33.59 ,A, P = .001; respective test-retest rs = 0.78 [P < .001] and 0.46 [P < .05]). Also as hypothesized, the threshold values were higher (i.e., sensitivity lower) than previously reported for anterior and lateral tongue regions. Conclusions: The magnitude and reliability of electrical taste thresholds depends on the tongue region examined and the size of the electrodes used. These results suggest that relatively large electrodes should be considered for electrogustometric threshold testing, particularly when lingual regions not highly populated with taste buds are evaluated. [source] | |||||||||||||