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PubMed1976

Radioimmunological determination and characterization of cathodal trypsin-like immunoreactivity in normal human plasma.

A radioimmunological method for determination of human cathodal trypsin-like immunoreactivity is described. DFP-treated human cathodal trypsin is used as standard and tracer. Freshly drawn normal human plasma contains about 25 microgram/l of cathodal trypsin-like immunoreactivity measured as DFP-treated cathodal trypsin. The normally circulating cathodal trypsin-like immunoreactivity is shown to consist mainly of cathodal trypsinogen.

Animals↗

PubMed1983

Cathodal bands in electrophoretograms of creatine kinase isoenzymes in serum collected after cardiac surgery: a poor prognostic sign.

Of 708 patients who had undergone cardiac surgery, the serum of 23 showed one or two enzyme bands cathodal to CK-MM in creatine kinase (CK) isoenzyme electrophoretograms. Postoperative mortality rate during hospitalization was: no bands, 8.8%; one band, 13%, two bands, 63% (p less than 0.001). Patients whose sera showed cathodal bands were slightly older than those without, and their postoperative serum lactate dehydrogenase (LD) activity was greater, with very high proportions of LD 5. The two cathodal bands in patients who died differed in cathodal electrophoretic mobility from the two bands in survivors, implying that different enzyme forms were involved. All cathodal bands were inhibited by reagent containing diadenosine pentaphosphate, as was adenylate kinase from erythrocytes and liver cytoplasm. Mitochondrial CK from liver and presumed mitochondrial CK in serum from a patient with malignancy were not inhibited. We conclude that the appearance of two enzyme bands cathodal to CK-MM, probably representing adenylate kinase and possibly originating from various tissues, is associated with a poor prognosis in patients after cardiac surgery.

Adenylate Kinase↗

PubMed1996

Prospective randomized comparison of anodal monophasic shocks versus biphasic cathodal shocks on defibrillation energy requirements.

Biphasic shocks are believed to be superior to monophasic shocks. Monophasic anodal shocks, as opposed to cathodal shocks, are associated with improved defibrillation energy requirements (DERs). However, it is unclear how the DER of anodal monophasic shocks compare with conventional biphasic shocks. Therefore the purpose of this study was to prospectively compare the DER of an anodal monophasic shock with that of a cathodal biphasic shock. A transvenous defibrillation lead with distal and proximal shocking electrodes was used. The subjects of this study were 20 consecutive patients with a mean age of 64.2 +/- 10.5 years ( +/- SD) and a mean left ventricular ejection fraction of 0.36 +/- 0.18. Six had had cardiac arrest. The DER, defined as the lowest energy that converted ventricular fibrillation to sinus rhythm, was determined twice with a step-down protocol (25 J, 20 J, 15 J, 10 J, 5 J, 3 J, 1 J). If the DER was > or = 25 J, then a subcutaneous patch was deemed necessary for system implantation. In random order the DER was determined with a monophasic anodal shock (distal electrode positive) and then with a cathodal (first phase, distal electrode negative) biphasic shock. The mean DER with anodal monophasic shocks was 15.1 +/- 8.5 J compared with 13.6 +/- 8.1 J with cathodal biphasic shocks (p = 0.4). A DER > or = 25 J was present in three patients with the monophasic waveform and in three patients with the biphasic waveform (p = NS). In conclusion, the DER and frequency of subcutaneous patch use with an anodal monophasic waveform is comparable to that obtained with cathodal biphasic waveform.

Aged↗

PubMed2005

Microbial fuel cell using anaerobic respiration as an anodic reaction and biomineralized manganese as a cathodic reactant.

We have operated a microbial fuel cell in which glucose was oxidized by Klebsiella pneumoniae in the anodic compartment, and biomineralized manganese oxides, deposited by Leptothrix discophora, were electrochemically reduced in the cathodic compartment. In the anodic compartment, to facilitate the electron transfer from glucose to the graphite electrode, we added a redox mediator, 2-hydroxy-1,4-naphthoquinone. We did not add any redox mediator to the cathodic compartment because the biomineralized manganese oxides were deposited on the surface of a graphite electrode and were reduced directly by electrons from the electrode. We have demonstrated that biomineralized manganese oxides are superiorto oxygen when used as cathodic reactants in microbial fuel cells. The current density delivered by using biomineralized manganese oxides as the cathodic reactant was almost 2 orders of magnitude higher than that delivered using oxygen. Several fuel cells were operated for 500 h, reaching anodic potentials of -441.5 +/- 31 mVscE and cathodic potentials of +384.5 +/- 64 mVscE. When the electrodes were connected by a 50 Ohms resistor, the fuel cell delivered the peak power density of 126.7 +/- 31.5 mW/m2.

Bioelectric Energy Sources↗

PubMed2005

Dual electrodes oxidation of dye wastewater with gas diffusion cathode.

The high energy cost of an electrochemical method is the fatal drawback that hinders its large scale application in wastewater treatment. In traditional single-chamber electrolysis cell, only direct oxidation at an anode exists. Although a small amount of hydrogen peroxide is produced at the cathode by reduction, it is transferred to the anode and destroyed there without adding much benefit to organic decomposition. A two-chamber electrolytic cell, connected with an electrolyte bridge, was developed in this work. In this new reactor, direct oxidation at anode and indirect oxidation by hydrogen peroxide at cathode can occur simultaneously. Therefore "dual electrodes oxidation" in one electrochemical reactor was achieved successfully. Compared to a traditional one cell reactor, this reactor cuts the energy cost by 50%, and thus might lead to reconsideration of the electrochemical role in wastewater treatment. A Pt/C gas diffusion electrode (GDE) is fabricated and used as a cathode fed with oxygen-containing gases to produce hydrogen peroxide. When purified air diffuses through the active layer on the GDE, oxygen is reduced to hydrogen peroxide with a high yield to decompose organics. It has been found that the direct oxidation process at an anodic zone is slightly affected by factors such as pH variation, Fe(II) existence and aeration, while indirect oxidation at the cathodic zone is strongly affected. Dye used as a model pollutant was oxidized into small organic acids in both anode and cathode regions in this electrolytic reactor. GC-MS and IR spectrum were employed to analyze the intermediates formed during the degradation. Twenty intermediates have been detected, including 14 esters, 3 acids and 3 compounds with NO2 or N-OH groups. Thereafter, the degradation pathways of dye Acid Red B are proposed.

Coloring Agents↗

PubMed2006

A bipolar membrane combined with ferric iron reduction as an efficient cathode system in microbial fuel cells.

There is a need for alternative catalysts for oxygen reduction in the cathodic compartment of a microbial fuel cell (MFC). In this study, we show that a bipolar membrane combined with ferric iron reduction on a graphite electrode is an efficient cathode system in MFCs. A flat plate MFC with graphite felt electrodes, a volume of 1.2 L and a projected surface area of 290 cm2 was operated in continuous mode. Ferric iron was reduced to ferrous iron in the cathodic compartment according to Fe(3+) + e(-) --> Fe2+ (E0 = +0.77 V vs NHE, normal hydrogen electrode). This reversible electron transfer reaction considerably reduced the cathode overpotential. The low catholyte pH required to keep ferric iron soluble was maintained by using a bipolar membrane instead of the commonly used cation exchange membrane. For the MFC with cathodic ferric iron reduction, the maximum power density was 0.86 W/m2 at a current density of 4.5 A/m2. The Coulombic efficiency and energy recovery were 80-95% and 18-29% respectively.

Bioelectric Energy Sources↗

PubMed1977

Neural substrate for brain stimulation reward in the rat: cathodal and anodal strength-duration properties.

The trade-off between current strength and duration of a stimulating pulse was studied for the rewarding and priming effects of brain stimulation reward (BSR). With cathodal pulses, strenght-duration functions for BSR had chronaxies of .8-3 msec. No differences were observed between the results for rewarding and priming effects. With anodal pulses. strength-duration curves were parallel to the cathodal curves at pulse durations of .1-5 msec, but at pulse durations greater than 5 msec the anodal curves showed a greater drop in required current intensity than did the cathodal curves. The parallel portion of the anodal curves was interpreted as due to anode-make excitation, and the drop at longer pulse durations was interpreted as due to anode-break excitation. Cathodal strength-duration functions for the motor effect elicited through the BSR electrodes had chronaxies of .15-.48 msec. Measurements of the latency of the muscle twitch confirmed that anode-make and anode-break excitation occurred, the latter becoming evident at pulse durations as brief as .3-.4 msec. The results provide quantitative characterization of cathodal and anodal strength-duration properties of the neural substrate for BSR and are discussed in terms of their value in guiding electrophysiological investigation of that substrate.

Animals↗

PubMed1992

Anodal and cathodal stimulation of the upper-limb area of the human motor cortex.

In 18 neurologically normal subjects the corticofugal volleys evoked by anodal and cathodal electrical stimulation of the motor cortex were recorded using epidural electrodes at the high-thoracic and low-thoracic regions of the spinal cord during surgery for scoliosis. At and just above threshold, anodal and cathodal stimulation of the upper-limb area and motor cortex produced a D wave that propagated to the low-thoracic region. The stimulus intensity required to produce D waves was significantly lower with anodal stimulation. I waves were recorded at higher stimulus intensities than the D wave but not more readily with cathodal stimulation. There was no significant difference in the extent to which stimulus intensity had to be increased above D-wave threshold to produce I waves with the two stimulus polarities, and the number of I waves was the same when the stimulus was increased by the same amount above D-wave threshold. After withdrawal of isoflurane, I waves could not be recorded when the stimulus intensity was below D-wave threshold with either stimulus polarity. Anodal stimulation over the upper-limb area remained more effective than cathodal stimulation in producing both D and I waves. These results indicate that, at threshold, regardless of anaesthesia, anodal and cathodal stimuli access upper-limb corticospinal neurons directly at a similar site, the anodal stimuli being more effective. In addition, the results suggest that some corticospinal neurons in the upper-limb area of motor cortex have projections to lumbar segments.

Adolescent↗

PubMed2000

Osmium-metal coating device using hollow-cathode plasma CVD method.

A novel osmium-metal coating device for SEM observation has been developed to prevent negative charge build-up on specimens by applying the hollow-cathode low voltage discharge plasma chemical vapour deposition (CVD) method. The CVD method using the hollow-cathode offers the following advantages. (i) The method can deposit osmium-metal at very low discharge voltage that is as low as half of that of the planar parallel electrode method. Therefore, the method avoids damage due to ion bombardment during the coating process. (ii) The method can minimize the quantity of the OsO4 gas by introducing directly into the hollow-cathode. This feature is important to prevent the air pollution caused by the purged gas. (iii) A large coating area is guaranteed because the Os ion is filled in the hollow-cathode where the specimen is holed. (iv) The lower discharge voltage can be used by mixing Ar, N2 or air with the OsO4 gas as the environmental gas in the chamber. (v) The hybrid coating is also available by lining the appropriate metal material such as platinum (Pt) on the surface of the inside of the hollow-cathode. The method uses the plasma CVD of Os metal as well as the ion-sputter deposition of the lined metal.

Animals↗

PubMed2005

Rapid start of oscillations in a magnetron with a "transparent" cathode.

We report on the improvement of conditions for the rapid start of oscillations in magnetrons by increasing the amplitude of the operating wave that is responsible for the capture of electrons into spokes. This amplitude increase is achieved by using a hollow cathode with longitudinal strips removed, thereby making the cathode transparent to the wave electric field with azimuthal polarization. In addition, an optimal choice of the number and position of cathode strips provide favorable prebunching of the electron flow over the cathode for fast excitation of the operating mode. Particle-in-cell simulations of the A6 magnetron demonstrate these advantages of this novel cathode.

Journal Article↗

PubMed1978

A fast stabliization technique for oxygen sensors with low cathode current densities.

After application of the polarization voltage to a newly prepared oxygen sensor, an initial stabilization of several minutes to a few hours is required. The electrochemical phenomena accounting for this stabilization process are discussed. By far the slowest reaction is the change of the oxidation state of the noble metal cathode after application of the polarization voltage. During this process, reduction of surface oxides at the cathode causes a transient current. The contribution of this reaction to the total current is proportionately higher in the case of oxygen sensors with low cathode current densities (large cathode, membrane of low oxygen permeability) than in the case of sensors with microcathodes. For the first type of sensor, a technique has been developed which allows acceleration of this surface reaction by passing a high constant current across the cathode. With this technique, the stabilization time can be considerably shortened in a reproducible manner, and the sensor is ready to be used within 15 to 30 min of its preparation. This time is comparable to the stabilization time needed for sensors with microcathodes.

Blood Gas Analysis↗

PubMed1978

Oxygen electrode design criteria and performance characteristics: recessed cathode.

A computer simulation of the steady-state operation of recessed (Whalen-type) polarographic oxygen electrodes has been developed to give the design factors important for performance optimization. The simulation makes use of a specially formulated three-dimensional orthogonal coordinate system with the geometry identical to the actual recessed cathode and gives the oxygen concentration field induced by it in the surrounding medium. Equations are presented which allow one to calculate, for any recessed cathode, the current sensitivity, maximum stirring artifact, measurement error, and time constant. Comparisons with analytically obtained expressions for the corresponding quantities for idealized, spherosymmetric cathodes demonstrate the unique aspects of recessed-cathode performance. For commonly used electrodes, a recess length-to-cathode diameter ratio of greater than 10 is found to give a negligible stirring artifact, a negligible measurement error, and a rapid response.

Computers↗

PubMed1994

RAPID AND SIMULTANEOUS MEASUREMENT OF ANODIC AND CATHODIC HAEMOGLOBINS AND ATP AND GTP CONCENTRATIONS IN MINUTE QUANTITIES OF FISH BLOOD

Oxygen transport to vertebrate tissues is dependent upon (a) the intrinsic O2-binding properties of haemoglobin (Hb) and (b) modulation by allosteric effectors, such as nucleoside triphosphates (NTP), that depress Hb O2-affinity in fish red cells. While some species, such as flatfish, primarily use adenosine triphosphate (ATP) to modulate O2-binding to Hb, others, such as eel and carp, also use guanosine triphosphate (GTP) (Kono and Hashimoto, 1977; Leray, 1982; Weber and Jensen, 1988). Unlike mammals, fish exhibit high degrees of molecular and functional Hb heterogeneity, which is manifested interspecifically but is also evident from polymorphism in different individuals of the same species (Weber, 1990). While some species such as carp have multiple Hbs that migrate anodally in normal electrophoresis and exhibit similar intrinsic oxygenation properties and sensitivities to NTP (Gillen and Riggs, 1972), others such as trout and eel have both anodic and cathodic components that exhibit different intrinsic O2-binding properties and different sensitivities to cofactors. Having higher O2 affinities and lower Bohr effects, the cathodic Hbs may be better adapted for O2 transport under hypoxic, hypercapnic or acidotic conditions than the anodic ones from the same species (Hashimoto et al. 1960; Binotti et al. 1971; Weber et al. 1975; Weber, 1990). Ambient hypoxia induces decreases in erythrocytic NTP (Wood and Johansen, 1972), which safeguards blood O2-loading in the gills. The concentrations of the major NTPs and anodic or cathodic Hbs are thus important indices of respiratory and adaptational status in fish. Erythrocytic ATP and GTP levels are generally assayed by thin layer or column chromatography or enzymatically, total Hb is measured by spectrophotometry, and the anodic and cathodic composition of the Hbs present by electrophoresis or isoelectric focusing. We here report a method for rapid and simultaneous assay of ATP and GTP, and of anodic and cathodic Hbs, in minute (approximately 3 µl) quantities of fish blood. We used trout [Oncorhynchus mykiss, 101±8 g (s.e.m.); N=9], eel (Anguilla anguilla, 114±17 g; N=9) and carp (Cyprinus carpio, 1407±104 g; N=9) supplied by local pisciculturists. The fish were kept for at least 1 week in 1 m3 glass fibre tanks with aerated running fresh water at 15 °C before experimentation. Blood samples were drawn from the caudal blood vessels into heparinised syringes.

Journal Article↗

PubMed2005

[Degradation mechanism of acid red B by cathodic oxidation].

Acid red B (ARB) solution with pH = 3 was electrolyzed in a two-chamber cell using Pt/C gas diffusion electrode (GDE) as cathode. The color and COD removal ratio in cathode chamber were 94.2% and 66.8% respectively; and the color and COD removal ratio in anode chamber were 73.3% and 56.6% respectively, which indicated that O2 can be reduced to H2O2 and x OH in the cathode chamber, then ARB was degraded. Through IR and GC-MS analysis for the intermediates of ARB in the cathode chamber, 20 intermediates have been detected, including 14 esters, 3 acids and 3 compounds with -NO2 or N-OH groups and the probable degradation pathway of ARB in the cathode chamber was given.

Coloring Agents↗

PubMed1989

Electrochemical treatment of cancer. I: Variable response to anodic and cathodic fields.

Percutaneous placement of an intraneoplasmic electrode in pulmonary metastases of three patients with extrathoracic primary cancers permitted electrochemical treatment of these lesions. These reacted variably to anodic and cathodic electrodes. One breast cancer metastasis disappeared after treatment with the anodic field. A small metastasis from a cancer of the urinary bladder was found to be resistant to both anodic and cathodic fields despite large doses of current. Two large metastases of about equal size from the leiomyosarcoma of the uterus showed progression of the cranial anodic neoplasm but regression of the caudal cathodic neoplasm. At reversed polarity the cathodic neoplasm showed a tendency to regress and the caudal neoplasm continued to disappear. It appears that different neoplasms may show a variable response to anodic or cathodic fields or may show poor sensitivity to both fields.

Aged↗

PubMedDate not supplied

Electrically induced osteogenesis: relationship between charge, current density, and the amount of bone formed: introduction of a new cathode concept.

A study was performed exploring the relationship between charge, current density, and the amount of new bone formed in the medullary canal of the intact rabbit tibia. The results indicate that the amount of bone formed in the vicinity of a cathode is directly related to both current density and charge. Utilizing stainless steel cathodes delivering a constant current of 20 muamps, the optimum current density was found to be 1.06 X 10(3) muamps/mm2 and the optimum charge, 36.29 coulombs. The amount of bone formed with pulsed current approached that formed with constant current only as the total charge delivered by the pulsed current approached that delivered by the constant current. Based on these findings, a new cathode is designed with eight active ports evenly distributed along its length and providing two and one-half times the amount of bone formed by a conventional cathode. This cathode is now in the early stages of clinical evaluation in patients with acquired nonunion.

Animals↗

PubMed2026

Decoupled Synthesis Pathway via Precursor Functionalization Stabilizes High-Voltage Nickel-Based Cathodes.

Nickel-based layered cathodes are promising candidates for high-performance, high-energy lithium-ion batteries, yet their high-voltage application is jointly limited by synthesis-inherited structural defects and an unstable lattice oxygen framework. Here, we show that both limitations can be overcome by decoupled synthesis pathway (DSP) via La/Nb oxalate functionalization of the Ni0.6Co0.1Mn0.3(OH)2 precursor. Unlike the conventional coupled synthesis pathway (CSP) where precursor dehydration and Li2CO3 decomposition overlap in temperature, the DSP introduces a low‑temperature decomposition of La/Nb oxalates at 200°C, which effectively avoids localized contact between the precursor and Li2CO3 and shifts Li2CO3-related reactions to high temperatures. This allows sequential precursor dehydroxylation, rock‑salt (RS) intermediate formation, and layered‑phase transformation over a broad temperature window. The resulting LiNi0.6Co0.1Mn0.3O2 cathode with La/Nb functionalization (NCM-LN) features a uniform surface LaNiO3 perovskite heterostructure and a Nb‑doped layered bulk with suppressed RS and spinel defects. Consequently, under 4.5 V operation (vs. Li+/Li), NCM-LN exhibits homogeneous Li+ (de)intercalation, and a stabilized oxygen framework. In graphite||NCM-LN full cells, NCM-LN retains 80.1% of its capacity after 2000 cycles at 1C, substantially outperforming the pristine cathode. This decoupling strategy is broadly effective across various Ni‑based systems, providing a generalizable route toward high‑energy, long‑life cathode materials.

decoupled synthesis pathway↗

PubMedDate not supplied

Cathodic electrochemiluminescence of acetonitrile, acetonitrile-1,10-phenanthroline and acetonitrile-ternary Eu(III) complexes at a gold electrode.

Cathodic electrochemiluminescence (ECL) behaviours of the acetonitrile, acetonitrile-1,10-phenanthroline (phen) and acetonitrile-ternary Eu(III) complex systems at a gold electrode were studied. One very weak cathodic ECL-2 at -3.5 V was observed in 0.1 mol/L tetrabutylammonium tetrafluoroborate (TBABF(4)) acetonitrile solution. When 10 mmol/L tetrabutylammonium peroxydisulphate [(TBA)(2)S(2)O(8)] was added to 0.1 mol/L TBABF(4) acetonitrile solution, another cathodic ECL-1 at -2.7 V appeared and the potential for ECL-2 was shifted from -3.5 to -3.1 V. Furthermore, ECL-2 intensity was enhanced about 20-fold. When 1 x 10(-4) mol/L phen was added to 0.1 mol/L TBABF(4) + 10 mmol/L (TBA)(2)S(2)O(8) acetonitrile solution, the ECL intensities of ECL-1 and ECL-2 were enhanced about 20-fold compared with those of 0.1 mol/L TBABF(4) + 10 mmol/L (TBA)(2)S(2)O(8) acetonitrile solution. The maximum emission peaks of ECL-1 and ECL-2 in the three systems mentioned above appeared at about 530 nm. The products obtained by electrolysing 0.1 mol/L TBABF(4) acetonitrile solution at -3.5 V for 20 min were analysed by Fourier Transform Infrared (FTIR) spectra and gas chromatography-mass spectrometry (GC-MS) and the emitter of ECL-1 and ECL-2 was identified as excited state polyacetonitrile. When ternary Eu(III) complexes were presented in 0.1 mol/L TBABF(4) + 10 mmol/L (TBA)(2)S(2)O(8) acetonitrile solution, another maximum emission peak with a narrow band centred at about 610 nm appeared in ECL-1 in addition to the maximum emission peaks at about 530 nm for ECL-1 and ECL-2. The emitter of ECL emission at 610 nm was identified as the excited states Eu(III)*. The mechanisms for cathodic ECL behaviours of the acetonitrile, acetonitrile-phen and acetonitrile-ternary Eu(III) complex systems at a gold electrode have been proposed. The extremely sharp emission bands for ternary Eu(III) complexes may have analytical potential.

Acetonitriles↗