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1
Xiao, S., and G. M. Haarberg. "Depolarized SnO2-based gas anodes for electrowinning of silver in molten chlorides." Journal of Mining and Metallurgy, Section B: Metallurgy 49, no. 1 (2013): 71–76. http://dx.doi.org/10.2298/jmmb121014026x.
Повний текст джерелаАнотація:
SnO2-based porous anodes were prepared and the behavior of gas bubbles on the porous anodes with different original coarse grain size, immersed in ethanol to simulate molten chlorides, was primarily investigated. SnO2-based porous anodes were used as gas anodes for the electrowinning of silver in CaCl2-NaCl-CaO-AgCl melts at 680?C. Hydrogen was introduced to the anode/electrolyte interface through the gas anode. Carbon was used as the cathode. Obvious depolarization of the anode potential was observed after the introduction of hydrogen comparing with no reducing gas introduced, indicating the involvement of hydrogen in the anode reaction. Metallic silver was deposited on the cathode.
2
Jeong, Jin A., and Chung Kuk Jin. "The Study on the Cathodic Protection Effect of the ICCP Anodes with Exposed Conditions." Applied Mechanics and Materials 681 (October 2014): 218–21. http://dx.doi.org/10.4028/www.scientific.net/amm.681.218.
Повний текст джерелаАнотація:
This paper presents the results of the effects of anodes for impressed current cathodic protection (ICCP) system on reinforced concrete. Experimental tests were carried out on reinforced concrete specimens with 3 different kinds of commercial anodes that are used for ICCP in order for comparative study. Results have shown that the type of anodes is irrelevant to the effectiveness of cathodic protection. CP current similarly flowed to the anodes regardless of anode types in seawater condition. In addition, current was much higher in seawater condition than freshwater and air condition. The results show that titanium rod anode was slightly more effective in fresh water, and titanium mesh anode showed a better performance in atmospheric condition. The potential drop caused by concrete resistance in atmospheric condition should be considered at depolarization potential measurement.
3
Jeong, Jin A., and Chung Kuk Jin. "The Experimental Measurement on the Throwing Power of Sacrificial Anode Cathodic Protection for Concrete Piles in Natural Sea Water." Advanced Materials Research 1125 (October 2015): 350–54. http://dx.doi.org/10.4028/www.scientific.net/amr.1125.350.
Повний текст джерелаАнотація:
This paper represents the experimental studies on the throwing power of sacrificial anode cathodic protection system applied to reinforced concrete piles in salt water condition by means of zinc anodes. Many previous studies show the effectiveness of sacrificial anode cathodic protection system, however, the major problem of sacrificial anode cathodic protection system is limited a distance to the point reaching protection current from the anode in high resistivity environments such as concrete, etc. In case of concrete pile in sea water condition, it should be combined submerged zone, tidal zone, splash zone, and atmospheric zone. In this study, the cathodic protection current by zinc sacrificial anodes was limited to scores of centimeters above the water line with tidal, depending on the concrete resistivity. Experimental tests were carried out on pile type reinforced concrete specimens with the change of water level. The test factors were corrosion and protection potential, current, and 4 hour depolarization potential. As a result of tests, cathodic protection current by zinc sacrificial anode was influenced up to about 10cm above the water line, and high resistivity areas such as atmospheric zone could not be protected with this system.
4
Jeong, Jin A., and Chung Kuk Jin. "Three Year Performance of Sacrificial Anode Cathodic Protection System in the Reinforced Concrete Bridge Structures." Advanced Materials Research 753-755 (August 2013): 467–75. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.467.
Повний текст джерелаАнотація:
The aim of this study was to obtain special cathodic protection (CP) behavior in coastal bridge structures. This bridge structure was located to the area where repetition between fresh water and sea water taken place due to ebb and flood tide. In this study, zinc-mesh anode was used as a sacrificial anode. Thus, it was a good opportunity to verify the effectiveness of sacrificial anode CP (SACP) in this special location. Measurement was conducted for three years. Test Factors were corrosion potential, CP potential, 4 hour depolarization potential, and CP current. Moreover, resistivity and corrosion rate were measured by the multi-functional corrosion monitoring sensor (DMS-100, Conclinic Co. Ltd) that could measure potential, galvanic current, corrosion rate, concrete resistivity, and temperature. After three years from installation of CP, it could confirm that although some pier showed low depolarization potential less than 100mV, most piers showed good protection both electrochemical and physical aspects.
5
Jeong, Jin A. "Cathodic Protection Effect of Reinforced Concrete Beam Specimens with Zinc Sacrificial Anode in Marine Environment." Advanced Materials Research 1125 (October 2015): 345–49. http://dx.doi.org/10.4028/www.scientific.net/amr.1125.345.
Повний текст джерелаАнотація:
This study is to acquire the confirmation data regarding the cathodic protection characteristics for reinforced concrete beam specimens with zinc sacrificial anode in 15% salt water. It was possible to confirm the performance of sacrificial anode cathodic protection system by the measurement of potentials and concrete resistivity for the reinforced concrete beam specimens applied with zinc sacrificial anode in mortar topside of the concrete specimens. The corrosion potential and cathodic protection potential were measured by potentiostat, and 4 hour depolarization potentials were measured after disconnecting with anode for 4 hours. It was confirmed that the cathodic protection for reinforced concrete structures by means of zinc sacrificial anode were very effective corrosion protection technology in marine environments.
6
Asavadorndeja, Pornpong, and Ulrich Glawe. "Electrokinetic strengthening of soft clay using the anode depolarization method." Bulletin of Engineering Geology and the Environment 64, no. 3 (August 2005): 237–45. http://dx.doi.org/10.1007/s10064-005-0276-7.
Повний текст джерела
7
Tung, Leslie, and Michel Neunlist. "Regional depolarization of cardiac muscle adjacent to an epicardial stimulating anode." American Heart Journal 124, no. 3 (September 1992): 834. http://dx.doi.org/10.1016/0002-8703(92)90318-p.
Повний текст джерела
8
ROTH, BRADLEY J., and JUN CHEN. "MECHANISM OF ANODE BREAK EXCITATION IN THE HEART: THE RELATIVE INFLUENCE OF MEMBRANE AND ELECTROTONIC FACTORS." Journal of Biological Systems 07, no. 04 (December 1999): 541–52. http://dx.doi.org/10.1142/s0218339099000310.
Повний текст джерелаАнотація:
Two hypotheses for the mechanism of anode break excitation in cardiac tissue are electrotonic interaction between adjacent regions of depolarization and hyperpolarization, and a hyperpolarization-activated membrane current, if. We incorporate membrane kinetics proposed for if into the bidomain model with unequal anisotropy ratios. During unipolar stimulation, we find that: (1) The mechanisms of cathode make, cathode break, and anode make excitation are insensitive to if. (2) Both electrotonic interactions and if contribute to anode break excitation. In our simulations, if makes the dominant contribution. (3) Electrotonic interactions cause the "dip" in the anodal strength-interval curve. (4) Following anode break excitation, the wave front propagates in the direction perpendicular to the fibers. (5) if improves the agreement between the measured and calculated strength-interval curves. We suggest three experiments to determine the mechanism of anode break excitation: measure the site and timing of initial excitation, or use drugs to suppress if.
9
Tabata, T., and A. T. Ishida. "Transient and sustained depolarization of retinal ganglion cells by Ih." Journal of Neurophysiology 75, no. 5 (May 1, 1996): 1932–43. http://dx.doi.org/10.1152/jn.1996.75.5.1932.
Повний текст джерелаАнотація:
1. Using whole cell patch-clamp methods, we have identified an inward cationic current activated by hyperpolarization (Ih) in somata of goldfish retinal ganglion cells. 2. Ih activated at test potentials between -70 and -105 mV, and did not appear to inactivate during prolonged hyperpolarizations under voltage clamp. During step hyperpolarizations from holding potentials between -70 and -40 mV, apparent activation was faster at more negative test potentials. On repolarization from -105 mV to holding potentials between -75 and -55 mV, Ih deactivated exponentially at rates showing no marked voltage dependence (tau = approximately 100 ms). 3. Ih tail currents reversed at membrane potentials consistent with a relative permeability to Na+ and K+ of roughly 0.5, when pipette and bath solutions both contained Na+ and K+. 4. Ih was readily blocked by extracellular Cs+ (3 mM), but was resistant to block by tetraethylammonium (30 mM), Ba2+ (1 mM), or Co2+ (2.4 mM). 5. Time-dependent voltage rectification developed during injection of hyperpolarizing current under current clamp. After current injection ceased, membrane potential depolarized beyond resting potential, often leading to anode-break-like spikes. Both voltage rectification and voltage overshoot were suppressed by extracellular Cs+. 6. Voltage-clamp measurements in the presence and absence of Cs+ were used to model membrane potential changes produced by exogenous current injections, by hyperpolarizing synaptic inputs, and by termination of both. Modeled responses resembled membrane potential changes measured under current clamp when terms for activation and deactivation of Ih were included. 7. The voltage rectification and anode-break-like spikes observed in isolated cells resemble those recorded during and after light-evoked hyperpolarizations of retinal ganglion cells in situ. Ih may transiently augment retinal ganglion cell excitability after termination of hyperpolarizing light stimuli, and thus promote encoding of stimulus timing.
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Jeong, Jin A. "Corrosion Test about Interference of Cathodic Protection Systems in Marine Concrete Structure." Advanced Materials Research 894 (February 2014): 129–33. http://dx.doi.org/10.4028/www.scientific.net/amr.894.129.
Повний текст джерелаАнотація:
When unprotected structures are nearby to CP systems, interference problems between unprotected and protected structures may be occurred. The stray current interference can accelerate the corrosion of nearby structures. During a recent few decades the protection technologies against stray current induced corrosion have been significantly improved and a number of techniques have been developed. However, there is very limited information in marine environments. In this study, cathodic protection systems installed both the ICCP with Ti-mesh anode and the SACP with zinc anode has been adopted to verify the current influence through laboratory experiment. CP potential and current have been investigated, moreover, 4 hour depolarization test has been involved to reveal the effectiveness of cathodic protection.
11
Jeong, Jin A. "Cathodic Prevention and Cathodic Protection of Concrete Slab with Zinc Sacrificial Anode." Applied Mechanics and Materials 597 (July 2014): 341–44. http://dx.doi.org/10.4028/www.scientific.net/amm.597.341.
Повний текст джерелаАнотація:
This study is to acquire the confirmation data regarding the cathodic protection and cathodic prevention characteristics for concrete slab specimens in marine environments. It was possible to confirm the performance of cathodic protection system by the measurement of potentials and current density for the concrete slab specimens applied with zinc mesh sacrificial anode in mortar topside of the concrete specimens. The current density for the cathodic protection (CProt) that CP started after a repair of corrosion was higher than that for the cathodic prevention (CPrev) that CP commenced from the beginning of experiment, and 4 hour depolarization potentials were higher in the CPrev system than in the CProt one, and it was confirmed that the CPrev has more protection effect with less protection current, comparing to the CProt. It was also confirmed that the CP of both CPrev and CProt by means of zinc mesh sacrificial anode for reinforced concrete structures were very effective corrosion protection technology in marine environments.
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Dai, Y., Y. Z. Song, D. L. Chen, W. H. Song, J. M. Xie, and Y. Ye. "Depolarization of Lithium Iron Phosphate Batteries by Multi-Walled Carbon Nanotube/Graphite Double-Layer Anode." Russian Journal of Physical Chemistry A 94, no. 8 (August 2020): 1628–35. http://dx.doi.org/10.1134/s003602442008004x.
Повний текст джерела
13
Jeong, Jin A., and Chung Kuk Jin. "Characteristic of CP Potential for Concrete Pile Specimen with Hybrid CP." Advanced Materials Research 685 (April 2013): 3–7. http://dx.doi.org/10.4028/www.scientific.net/amr.685.3.
Повний текст джерелаАнотація:
This study represents the result of hybrid cathodic protection (Hybrid CP) system application. Hybrid CP, which is the combination between sacrificial anode cathodic protection (SACP) system and impressed current cathodic protection (ICCP) system, can be optimum way to protect corrosion, especially in concrete columns. In this study, sections below a water line, i.e. submerged and tidal zones, were cathodically protected by means of SACP. In addition, ICCP was applied to the upper areas of water line, i.e. splash and atmospheric zones. Water level was changed to verify the effectiveness of hybrid CP system. The test factors were natural, CP, and 4-hour depolarization potential.
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Jeong, Jin A., and Chung Kuk Jin. "Utilization of Variable Resistor for Improvement of Impressed Current Cathodic Protection System on Reinforced Concrete Structures." Advanced Materials Research 1125 (October 2015): 365–69. http://dx.doi.org/10.4028/www.scientific.net/amr.1125.365.
Повний текст джерелаАнотація:
This study is to acquire the confirmation data regarding the impressed current cathodic protection (ICCP) system by using the variable resistor for reinforced concrete specimens for improvement in under-protected area of reinforced concrete specimens. The ICCP system is one of the most promising corrosion protection methods. The Effect of ICCP system can be changed at diverse conditions. Particularly, temperature and relative humidity plays a crucial role in the CP effect. It was possible to confirm the performance of ICCP system by the use of variable resistor in different relative humidity and temperature conditions. The CP potential and current were measured by potentiostat, and 4 hour depolarization potentials were measured after disconnecting with anode for 4 hours. To enhance the effect of cathodic protection system, seawater was used as an electrolyte. Used anode for ICCP system was mixed metal oxide (MMO) titanium. From this study, it could be confirmed that the CP potential and current were highly influenced by temperature and relative humidity, and the CP effect in under-protected area has been improved by the ICCP system using the variable resistor.
15
Jeong, Jin A., and Chung Kuk Jin. "Experimental Study on the Effect of Cathodic Protection System for Concrete Slab Specimens with Zn-Mesh Sacrificial Anode in Marine Environment." Advanced Materials Research 785-786 (September 2013): 264–72. http://dx.doi.org/10.4028/www.scientific.net/amr.785-786.264.
Повний текст джерелаАнотація:
This study is to acquire the confirmation data regarding the cathodic protection (CP) characteristics for slabs in marine bridges and piers exposed to hash seawater environments. It was possible to confirm the performance of CP only by the measurement of CP potentials for the slab specimens applied with zinc mesh sacrificial anode CP system. The CP current density for the cathodic protection (CProt) that CP started after a repair of corrosion was 2 times higher than that for the cathodic prevention (CPrev) that CP commenced from the beginning of experiment, and the most of protection current density (87.0-91.5%) flew to the closer top rebar in slab specimens. 4 hour depolarization potentials were higher in the CPrev system than in the CProt one, and it was confirmed that the CPrev has more protection effect with less protection current, comparing to the CProt. It was also confirmed that the CP of both CPrev and CProt by means of zinc mesh sacrificial anode for reinforced concrete structures were very effective corrosion protection technology in marine environment.
16
Jeong, Jin A. "Cathodic Prevention and Cathodic Protection of Zinc Mesh Sacrificial Anode for Reinforced Concrete in 15% Salt Water." Applied Mechanics and Materials 665 (October 2014): 167–71. http://dx.doi.org/10.4028/www.scientific.net/amm.665.167.
Повний текст джерелаАнотація:
This study is to acquire the confirmation data regarding the cathodic protection and cathodic prevention characteristics for concrete piles in marine bridges and piers exposed to harsh marine environments. It was possible to confirm the performance of cathodic protection by the measurement of potentials and current density the concrete pile specimens applied with zinc mesh sacrificial anode cathodic protection system. The current density for the cathodic protection (CProt) that CP started after a repair of corrosion was higher than that for the cathodic prevention (CPrev) that CP commenced from the beginning of experiment, and 4 hour depolarization potentials were higher in the CPrev system than in the CProt one, and it was confirmed that the CPrev has more protection effect with less protection current, comparing to the CProt.
17
Savastru, Cristina, and Alexandru M. Morega. "An Electrical Field Numerical Simulation of Implantable Pacing Electrodes." Key Engineering Materials 583 (September 2013): 119–24. http://dx.doi.org/10.4028/www.scientific.net/kem.583.119.
Повний текст джерелаАнотація:
The heart functions normally when the impulses are produced at a rate of 80 bpm. When less than 60 bpm are triggered, pacemakers may be necessary to sustain the electrical activity of the heart. Pacemaker systems used in cardiac resynchronization therapy are made of an implantable pulse generator, leads, and unipolar or bipolar electrodes. They are aimed to simulate the cardiac depolarization, to sense intrinsic cardiac functions, to provide information stored by the system for deeper diagnosis. This paper presents a mathematical model and numerical simulation results on the ionic current distributed by the electrodes, in the absence of concentration gradients, in the cardiac tissue. The external electrical resistance variation with the anode to cathode spacing obtained by this approach may be used in the design phase of the device.
18
Chernyshova, O. V., T. B. Yelemessov, and D. V. Drobot. "Application of pulse current for dissolution of heat-resistant GS32-VI alloy." Fine Chemical Technologies 16, no. 5 (November 28, 2021): 438–47. http://dx.doi.org/10.32362/2410-6593-2021-16-5-438-447.
Повний текст джерелаАнотація:
Objectives. To identify the regularities of electrochemical processing of the heat-resistant GS32-VI alloy in a sulfuric acid electrolyte with a concentration of 100 g/dm3 under the action of a pulsed current in a pulsed mode.Methods. Using the electrochemical technological complex EHK-1012 (developed by IP Tetran) and a non-compensatory method of measuring potential, polarization and depolarization curves with a change in pulse duration and a pause between them were recorded. The current pulses had an amplitude ranging from 0 to 3.5 A (when recording the polarization and depolarization curves), pulse durations ranging from 200 to 1200 ms, and a pause (delay) between pulses ranging from 50 to 500 ms. There were no reverse current pulses.Results. The parameters of the current program that provide the maximum values of the alloy dissolution rate and current output were determined: with a current pulse amplitude of 2 A, a current pulse duration of 500 ms, and a pause duration between pulses of 250 ms, the maximum dissolution rate of the alloy is 0.048 g/h·cm2, while the current output for nickel is 61.6% with an anode area of 10 cm2. The basic technological scheme for processing the heat-resistant GS32-VI alloy, which includes anodic alloy dissolution in a pulsed mode, is proposed.Conclusions. Electrochemical dissolution of GS32-VI alloy under pulsed current action results in an optimal dissolution rate ratio of the alloy components, ensuring the production of a cathode precipitate with a total nickel and cobalt content of 97.5%.
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Herzog, R. I., T. R. Cummins, and S. G. Waxman. "Persistent TTX-Resistant Na+ Current Affects Resting Potential and Response to Depolarization in Simulated Spinal Sensory Neurons." Journal of Neurophysiology 86, no. 3 (September 1, 2001): 1351–64. http://dx.doi.org/10.1152/jn.2001.86.3.1351.
Повний текст джерелаАнотація:
Small dorsal root ganglion (DRG) neurons, which include nociceptors, express multiple voltage-gated sodium currents. In addition to a classical fast inactivating tetrodotoxin-sensitive (TTX-S) sodium current, many of these cells express a TTX-resistant (TTX-R) sodium current that activates near −70 mV and is persistent at negative potentials. To investigate the possible contributions of this TTX-R persistent (TTX-RP) current to neuronal excitability, we carried out computer simulations using the Neuron program with TTX-S and -RP currents, fit by the Hodgkin-Huxley model, that closely matched the currents recorded from small DRG neurons. In contrast to fast TTX-S current, which was well fit using a m3h model, the persistent TTX-R current was not well fit by an m3h model and was better fit using an mh model. The persistent TTX-R current had a strong influence on resting potential, shifting it from −70 to −49.1 mV. Inclusion of an ultra-slow inactivation gate in the persistent current model reduced the potential shift only slightly, to −56.6 mV. The persistent TTX-R current also enhanced the response to depolarizing inputs that were subthreshold for spike electrogenesis. In addition, the presence of persistent TTX-R current predisposed the cell to anode break excitation. These results suggest that, while the persistent TTX-R current is not a major contributor to the rapid depolarizing phase of the action potential, it contributes to setting the electrogenic properties of small DRG neurons by modulating their resting potentials and response to subthreshold stimuli.
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Díaz-Abad, Sergio, María Millán, Manuel A. Rodrigo, and Justo Lobato. "Review of Anodic Catalysts for SO2 Depolarized Electrolysis for “Green Hydrogen” Production." Catalysts 9, no. 1 (January 9, 2019): 63. http://dx.doi.org/10.3390/catal9010063.
Повний текст джерелаАнотація:
In the near future, primary energy from fossil fuels should be gradually replaced with renewable and clean energy sources. To succeed in this goal, hydrogen has proven to be a very suitable energy carrier, because it can be easily produced by water electrolysis using renewable energy sources. After storage, it can be fed to a fuel cell, again producing electricity. There are many ways to improve the efficiency of this process, some of them based on the combination of the electrolytic process with other non-electrochemical processes. One of the most promising is the thermochemical hybrid sulphur cycle (also known as Westinghouse cycle). This cycle combines a thermochemical step (H2SO4 decomposition) with an electrochemical one, where the hydrogen is produced from the oxidation of SO2 and H2O (SO2 depolarization electrolysis, carried out at a considerably lower cell voltage compared to conventional electrolysis). This review summarizes the different catalysts that have been tested for the oxidation of SO2 in the anode of the electrolysis cell. Their advantages and disadvantages, the effect of platinum (Pt) loading, and new tendencies in their use are presented. This is expected to shed light on future development of new catalysts for this interesting process.
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Timokhin, Viktor M. "Studying Breakdown and Electrical Hardening of Crystal Materials with Proton Conductivity." Key Engineering Materials 909 (February 4, 2022): 3–12. http://dx.doi.org/10.4028/p-en1raa.
Повний текст джерелаАнотація:
The breakdown mechanism of a number of crystal materials with hydrogen bonds is investigated. The contribution of the proton component is considered and it is shown that the formation of an avalanche-streamer discharge is characteristic of multilayer electrical insulation materials. As a result of the breakdown, a discharge channel is formed, along which the protons that form the reverse proton conductivity will move in the opposite direction. In the process of directed translational diffusion of protons, the formation and decay of H3O+ and OH-ions occur, which move in opposite directions, resulting in the formation of a reverse positive streamer from the anode to the cathode. For layered samples of phlogopite, muscovite, and magnesium hydrosilicate, it is shown that for thin samples, a volume charge is formed as a result of a multi-avalanche-streamer discharge that significantly exceeds the volume charge that occurs in thick samples, which is determined by the value of high temperature maximum of the spectrum of thermally stimulated depolarization currents. The field of the volume charge reduces the external electric field, as a result of which the breakdown field strength in thin samples increases. That is, the material is electrically strengthened. Based on the results of the research, a non-destructive method of electrical hardening of electrical insulation materials was developed, which was confirmed by the patent.
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Callaway, Joseph C., and William N. Ross. "Spatial Distribution of Synaptically Activated Sodium Concentration Changes in Cerebellar Purkinje Neurons." Journal of Neurophysiology 77, no. 1 (January 1, 1997): 145–52. http://dx.doi.org/10.1152/jn.1997.77.1.145.
Повний текст джерелаАнотація:
Callaway, Joseph C. and William N. Ross. Spatial distribution of synaptically activated sodium concentration changes in cerebellar Purkinje neurons. J. Neurophysiol. 77: 145–152, 1997. The spatial distribution of Na+-dependent events in guinea pig Purkinje cells was studied with a combination of high-speed imaging and simultaneous intracellular recording. Individual Purkinje cells in sagittal cerebellar slices were loaded with either fura-2 or the Na+ indicator sodium binding benzofuran isophthalate (SBFI) with sharp electrodes or patch electrodes on the soma or dendrites. [Na+]i changes were detected in response to climbing fiber and parallel fiber stimulation. These changes were located both at the anatomically expected sites of synaptic contact in the dendrites and in the somatic region. The variation in time course of these [Na+]i changes in different locations implies that Na+ enters at the synapse and diffuses rapidly to locations of lower initial [Na+]i. The synaptically activated somatic [Na+]i changes probably reflect Na+ entry through voltage-sensitive Na+ channels because they were detected only when regenerative potentials were recorded in the soma. [Na+]i changes in response to antidromically or intrasomatically evoked Na+ action potentials also were confined to the cell body. These observations are in agreement with other evidence that Na+ spikes are generated in the somatic region of the Purkinje neuron and spread passively into the dendrites. Plateau potentials, evoked by depolarizing pulses to the soma or dendrites, caused [Na+]i changes only in the soma, indicating that the noninactivating Na+ channels contributing to this potential also were concentrated in this region. The climbing fiber-activated [Na+]i changes were blocked by the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione, indicating that these changes were not due to direct stimulation of the Purkinje neuron or activation of metabotropic receptors. Direct depolarization of the soma or dendrites never caused dendritic [Na+]i increases, suggesting that the climbing fiber-activated [Na+]i changes in the dendrites are due to Na+ entry through ligand-gated channels. A climbing fiber-like regenerative potential could be recorded in the soma after anode break stimulation, parallel fiber activation, or depolarizing pulses to the soma. The [Na+]i changes evoked by all of these potentials were confined to the cell body region of the Purkinje cell. [Ca2+]i changes in the dendrites evoked by the anode break potential were small relative to climbing fiber-activated changes, suggesting that a Ca2+ spike was not evoked by this response. The anode break and directly responses were blocked by tetrodotoxin. These results suggest that the somatically recorded climbing fiber response is predominantly a Na+-dependent event, consisting of a few fast action potentials and a slower regenerative response activating the same channels as the Na+ plateau potential.
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Huang, R. C. "Sodium and calcium currents in acutely dissociated neurons from rat suprachiasmatic nucleus." Journal of Neurophysiology 70, no. 4 (October 1, 1993): 1692–703. http://dx.doi.org/10.1152/jn.1993.70.4.1692.
Повний текст джерелаАнотація:
1. Neurons were acutely dissociated from the suprachiasmatic nucleus (SCN) of adult rats and studied with whole-cell and perforated-patch recordings at room temperature. 2. Acutely dissociated SCN neurons had spherical cell bodies of 12 microns in average diameter. The recorded cells were randomly selected and had either no process (38%), one (41%), two (19%), or three processes (2%). They had a resting potential of about -60 mV, an input resistance of approximately 5 G omega, and a cell capacitance of approximately 7 pF. 3. The dissociated neurons had variable spontaneous firing rates, typically (76%) < 1 Hz. 4. Under current clamp, continuous current injection elicited repetitive action potentials. 1 microM tetrodotoxin (TTX) reduced the amplitudes of the action potentials as well as the firing rate, whereas 200 microM Cd2+ stopped repetitive firing altogether. Action potentials were completely eliminated with Cd2+ and TTX present. These results suggest that both Na+ and Ca2+ contribute to the action potential in these cells. 5. With 200 microM Cd2+ present to block calcium currents, a train of brief depolarizing pulses could still elicit repetitive sodium action potentials, but these became attenuated at stimulating frequencies as low as 1 Hz. 6. Under voltage clamp, the sodium current was activated at about -40 mV and peaked at about -10 mV. It inactivated with a time constant of approximately 0.5 ms at 0 mV, and in steady state the current was half-inactivated at about -60 mV. Recovery of the current from inactivation showed two very different phases with time constants of approximately 30 and 600 ms at -60 mV. The slow phase was probably responsible for the very low firing rate of the sodium action responsible for the very low firing rate of the sodium action potential. 7. In the absence of external sodium, depolarization-activated calcium action potentials were preferentially blocked by 20 microM Cd2+, whereas a posthyperpolarizing depolarizing (or anode break) was preferentially reduced by 100 microM Ni2+. These differential effects hinted at the presence of both low-threshold and high-threshold calcium currents in these cells. 8. Voltage-clamp experiments confirmed the presence of a low-threshold, transient calcium current that was activated by depolarizations above -70 mV. It inactivated with a time constant of approximately 25 ms between -50 and -30 mV. Steady-state inactivation was half-complete at about -90 mV and complete at about -70 mV.(ABSTRACT TRUNCATED AT 400 WORDS)
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Cheng, David Ker-Liang, Leslie Tung, and Eric A. Sobie. "Nonuniform responses of transmembrane potential during electric field stimulation of single cardiac cells." American Journal of Physiology-Heart and Circulatory Physiology 277, no. 1 (July 1, 1999): H351—H362. http://dx.doi.org/10.1152/ajpheart.1999.277.1.h351.
Повний текст джерелаАнотація:
The response of cellular transmembrane potentials ( V m) to applied electric fields is a critical factor during electrical pacing, cardioversion, and defibrillation, yet the coupling relationship of the cellular response to field intensity and polarity is not well documented. Isolated guinea pig ventricular myocytes were stained with a voltage-sensitive fluorescent dye, di-8-ANEPPS (10 μM). A green helium-neon laser was used to excite the fluorescent dye with a 15-μm-diameter focused spot, and subcellular V m were recorded optically during field stimulation directed along the long axis of the cell. The membrane response was measured at the cell end with the use of a 30-ms S1-S2 coupling interval and a 10-ms S2 pulse with strength of up to ∼500-mV half-cell length potential (field strength × one-half the cell length). The general trends show that 1) the response of V m at the cell end occurs in two stages, the first being very rapid (<1 ms) and the second much slower in time scale, 2) the rapid response consists of hyperpolarization when the cell end faces the anode and depolarization when the cell end faces the cathode, 3) the rapid response varies nonlinearly with field strengths and polarity, being relatively larger for the hyperpolarizing responses, and 4) the slower, time-dependent response has a time course that varies in slope with field strength. Furthermore, the linearity of the dye response was confirmed over a voltage range of −280 to +140 mV by simultaneous measurements of optically and electrically recorded V m. These experimental findings could not be reproduced by the updated, Luo-Rudy dynamic model but could be explained with the addition of two currents that activate outside the physiological range of voltages: a hypothetical outward current that activates strongly at positive potentials and a second current that represents electroporation of the cell membrane.
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Dekin, M. S. "Inward rectification and its effects on the repetitive firing properties of bulbospinal neurons located in the ventral part of the nucleus tractus solitarius." Journal of Neurophysiology 70, no. 2 (August 1, 1993): 590–601. http://dx.doi.org/10.1152/jn.1993.70.2.590.
Повний текст джерелаАнотація:
1. An in vitro brain stem slice from adult guinea pigs was used to study the effects of membrane hyperpolarization in two classes of bulbospinal neurons, called types I and II, from the ventral parts of the nucleus tractus solitarius (vNTS). These bulbospinal neurons project to the phrenic motor nucleus and make up the dorsal respiratory group, a sensorimotor integrating area for rhythmic breathing movements. 2. Negative current injections (1 s long) were used in the discontinuous current-clamp mode to study the input resistance (Rin) in both classes of bulbospinal vNTS neurons. The mean Rin for type I neurons was 88.7 +/- 13.8 (SD) M omega (n = 19) and for type II neurons was 92.6 +/- 14.0 M omega (n = 16). Both classes of neurons displayed a depolarizing sag and inward rectification during negative current injections to membrane-potential levels less than or equal to -70 mV. The magnitude of the depolarizing sag became larger as the size of the negative current step was increased. On release from hyperpolarization, both cell types also exhibited a large anode break hyperpolarization (ABH). 3. The ABH was abolished in the presence of 5 mM 4-amino-pyridine (4-AP), whereas the depolarizing sag and inward rectification were not affected. In the place of the ABH, a small postinhibitory rebound (PIR) depolarization was observed on release from hyperpolarization. The magnitude of PIR was dependent on the size of the depolarizing sag. In the presence of both 5 mM 4-AP and 5 mM Cs+, the depolarizing sag and PIR were completely blocked, whereas Rin was increased. 4. The ionic currents underlying the ABH and depolarizing sag were directly observed by the use of the discontinuous single-electrode voltage-clamp technique. The ABH was caused by activation of an A-current (IKA). The depolarizing sag was associated with a hyperpolarization-activated inward current (IH), which was activated at membrane-potential levels less than or equal to -70 mV. The peak amplitude of IH in type I neurons was -335 +/- 16 pA (n = 13) and in type II cells was -327 +/- 14 pA (n = 11). 5. IH currents did not display inactivation during the hyperpolarizing voltage step. The IH current became larger when [K+]o was increased from 4 mM (control) to 12 mM and was blocked in the presence of 5 mM Cs+. The estimated reversal potential for the IH current was -41.5 +/- 4.8 mV (n = 8).(ABSTRACT TRUNCATED AT 400 WORDS)
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Hsiao, Chie-Fang, Christopher A. Del Negro, Peggy R. Trueblood, and Scott H. Chandler. "Ionic Basis for Serotonin-Induced Bistable Membrane Properties in Guinea Pig Trigeminal Motoneurons." Journal of Neurophysiology 79, no. 6 (June 1, 1998): 2847–56. http://dx.doi.org/10.1152/jn.1998.79.6.2847.
Повний текст джерелаАнотація:
Hsiao, Chie-Fang, Christopher A. Del Negro, Peggy R. Trueblood, and Scott H. Chandler. Ionic basis for serotonin-induced bistable membrane properties in guinea pig trigeminal motoneurons. J. Neurophysiol. 79: 2847–2856, 1998. Intracellular recordings and pharmacological manipulations were employed to investigate the ionic basis for serotonin-induced bistable membrane behaviors in guinea pig trigeminal motoneurons (TMNs). In voltage clamp, 10 μM serotonin (5-HT) induced a region of negative slope resistance (NSR) in the steady-state current-voltage ( I-V) relationship at potentials less negative than −58 mV, creating the necessary conditions for membrane bistability. The contributions of sustained Na+ and Ca2+ currents to the generation of the NSR were investigated using specific ion channel antagonists and agonists. The NSR was eliminated by the L-type Ca2+ channel antagonist nifedipine (5–10 μM), indicating the contribution of L channels. In nifedipine, inward rectification was present in the I-V relationship in a similar voltage range (greater than −58 mV). This region was subsequently linearized by tetrodotoxin (TTX), indicating the presence of a persistent Na+ current. When the 5-HT–induced NSR was eliminated by perfusion in low Ca2+ solution (0.4 mM), it was restored by the Na+ channel agonist veratridine (10 μM). Commensurate with bistability, in current clamp during bath application of 5-HT, plateau potentials were elicited by transient depolarizing or hyperpolarizing stimuli. Plateau potentials evoked by depolarization were observed under control and TTX conditions, but were blocked by nifedipine, suggesting the participation of an L-type Ca2+ current. Plateau potentials initiated after release from hyperpolarization (anode break) were blocked by 300 μM Ni2+, suggesting the responses relied on deinactivation of a T-type Ca2+ current. Conditional bursting was also observed in 5-HT. Nifedipine or low Ca2+ solutions blocked bursting, and the L-channel agonist Bay K 8644 (10 μM) extended the duration of individual bursts, demonstrating the role of L-type Ca2+ currents. Interestingly, when bursting was blocked by nifedipine or low Ca2+, it could be restored by veratridine application via enhancement of the persistent Na+ current. We conclude that bistable membrane behaviors in TMNs are mediated by L-type Ca2+ and persistent Na+ currents. 5-HT is associated with enhancement of TMN activity during oral-motor activity; the induction of bistable membrane properties by 5-HT represents a cellular mechanism for this enhancement.
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Laurens, Stephane, and Raoul Francois. "Cathodic protection in reinforced concrete structures affected by macrocell corrosion: a discussion about the significance of the protection criteria." RILEM Technical Letters 2 (December 5, 2017): 27–32. http://dx.doi.org/10.21809/rilemtechlett.2017.38.
Повний текст джерелаАнотація:
Cathodic protection is a technique that has been used to control corrosion and increase the service life of reinforced concrete structure. Standards as EN ISO 12696 give protection criteria for both impressed current and sacrificial anodes techniques, based on potential value or decay during a depolarization sequence. The polarization (current ON) and depolarization (current OFF) is experimentally studied on a corroded concrete wall thanks to six references electrodes and compared to a time-dependent modelling using FEM software COMSOL Multiphysics. Both experimental and numerical results show significant differences in the time response according to electrode location. This conclusion indicates that the concept of protection criteria defined by the standards is not suitable to assess the efficiency of cathodic protection applied to reinforced concrete structure.
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MUSHIAKE, Katsuhiko, Noboru MASUKO, and Masao TAKAHASHI. "Electrocatalytic Anodes for Zinc Electrowinning by Methanol Depolarization Process in Sulfuric Acid Bath." Journal of the Mining Institute of Japan 101, no. 1174 (1985): 787–93. http://dx.doi.org/10.2473/shigentosozai1953.101.1174_787.
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Edwards, F. R., and G. D. S. Hirst. "Mathematical description of regenerative potentials recorded from circular smooth muscle of guinea pig antrum." American Journal of Physiology-Gastrointestinal and Liver Physiology 285, no. 4 (October 2003): G661—G670. http://dx.doi.org/10.1152/ajpgi.00145.2003.
Повний текст джерелаАнотація:
Regenerative potentials evoked by intracellular current injection in single bundles of circular smooth muscle taken from guinea pig antrum have the characteristics of the secondary regenerative component of the slow wave occurring in the same muscle layer. Such regenerative depolarizations might result from a mechanism that responds to membrane polarization with a delayed increase in the rate of production of unitary potentials detected in this tissue. To test this possibility, a two-stage reaction leading to the formation of an intracellular messenger was proposed. The first forward reaction was voltage-dependent, in the manner described by the Hodgkin-Huxley transient Na conductance formalism, allowing simulation of anode break excitation, stimulus threshold strength-duration characteristics, and refractory behavior. A conventional dose-effect relationship was proposed to describe the dependence of the mean rate of discharge of unitary potentials on messenger concentration. Unitary potentials were modeled as unitary membrane conductance modulations with an empirically derived amplitude distribution and Poisson-distributed intervals. The model reproduces a range of spontaneous and evoked membrane potential changes characteristic of antral circular muscle bundles.
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Jeong, Jin A., and Chung Kuk Jin. "Effect of Cathodic Protection Systems with Zn-Mesh Sacrificial Anodes on Reinforced Concrete Structures in an Accelerated Marine Environment." Advanced Materials Research 800 (September 2013): 365–74. http://dx.doi.org/10.4028/www.scientific.net/amr.800.365.
Повний текст джерелаАнотація:
In the present study, corrosion and cathodic protection (CP) characteristics of concrete piles exposed to marine environments such as marine bridge columns or pier structures were evaluated under simulated conditions. The accelerated environmental tests were carried out at an elevated temperature (40°C) and a high chloride concentration (15%). The protection potential of CP systems with Zn-mesh sacrificial anodes applied to piles was inversely proportional to the water content in the concrete. When the CP system was applied after corrosion initiation and propagation (CProt), the protection current density was higher than when the CP system was applied at the beginning of structural construction (CPrev). However, the four-hour depolarization potential was higher in the latter case than in the former. In addition, it was found that even though the current density of the CPrev system was relatively lower than that of the CProt system, the CPrev system was also able to prevent corrosion. Consequently, both CProt and CPrev systems are very effective at preserving reinforced concrete structures, especially in marine environments.
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Curila, K., P. Jurak, P. Waldauf, J. Halamek, P. Stros, R. Smisek, F. Plesinger, et al. "Bilateral bundle branch capture during deep septal myocardial and nonselective left bundle branch pacing preserves interventricular synchrony." EP Europace 24, Supplement_1 (May 18, 2022). http://dx.doi.org/10.1093/europace/euac053.430.
Повний текст джерелаАнотація:
Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Health of the Czech Republic Background Both left bundle branch pacing (LBBP) and deep septal myocardial pacing (LVSP) are less physiological than His bundle pacing. However, pacing both anode and cathode of the lead that is positioned in the interventricular septum may provide bilateral bundle branch capture, which may result in better interventricular synchrony. Objective To use UHF-ECG to compare ventricular activation between HBp and bilateral bundle branch capture during left bundle branch (LBBPbi) and deep septal myocardial pacing (LVSPbi). Methods Studies were performed in consecutive bradycardia patients. Bipolar pacing was performed with the lead in the LBBP (pseudo right bundle branch block morphology in V1 + proved LBB capture) and LVSP (pseudo right bundle branch block morphology in V1 without proved LBB capture) positions, with the pacing output leading to bilateral bundle branch capture. QRS duration was measured from the first to the last deflection of the QRS in any lead. UHF-ECG electrical dyssynchrony parameters – e-DYS (difference between the first and last ventricular activation) and local depolarization durations in precordial leads (V1-V8d) were calculated. Results In 94 consecutive patients, measurements were performed during HBp (n = 75) and LVSPbi (n = 37) and LBBPbi (n = 64). The average pacing threshold leading to bilateral bundle branch capture was 2.6 V at 0.5 ms. nsHBp led to the shortest QRSd compared to sLBBPbi and LVSPbi (98 vs. 103 vs. 110 ms; p < 0.01). LVSPbi showed smallest e-DYS -2 ms vs. -8 ms during LBBPbi and 11 ms during nsHBp; p < 0.05, but V5-8d were during LVSPbi longer than during nsHBp and LBBPbi (absolute difference 4-9 ms); p < 0.05. No statistical difference in V5-V8d were observed between LBBPbi and nsHBp. Conclusion Bilateral bundle branch capture during LVSP and nsLBBp preserves interventricular synchrony at the same level as HBp and thus leads to more physiological ventricular activation in patients with bradycardia.
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Gravellone, M., G. Dell' Era, F. De Vecchi, E. Boggio, E. Prenna, C. Devecchi, M. Matta, et al. "Cathodic-anodal left ventricular stimulation during cardiac resynchronization therapy: haemodynamic evaluation and electrocardiographic analysis." European Heart Journal 41, Supplement_2 (November 1, 2020). http://dx.doi.org/10.1093/ehjci/ehaa946.0799.
Повний текст джерелаАнотація:
Abstract Background Cardiac resynchronization therapy (CRT) is an established treatment for heart failure with reduced ejection fraction (HFrEF). However, one third of patients are “non responders”. Cathodic-anodal (CA) left ventricle (LV) capture is a multisite pacing occurring during CRT using both bipolar and quadripolar LV lead. It allows depolarization to arise simultaneously from the cathode and the anode of the bipole located on the LV epicardium, activating a larger volume of myocardium than cathodal pacing alone, thus potentially improving electromechanical synchrony (figure 1). We have previously proven that CA-LV stimulation is feasible and similar to bicathodic multipoint pacing (MPP) in terms of QRS wavefront activation. Purpose We aimed to evaluate both the acute intraprocedural haemodynamic and electrical effects of CA biventricular stimulation (CA-BS), comparing it with right-ventricle only pacing (Right Ventricle-Stimulation: RV-S), single-point CRT (Single Point-Biventricular Stimulation: SP-BS) and multipoint bicathodic biventricular stimulation (Multi Point-Biventricular Stimulation:MP-BS) in de novo CRT implants. Methods Ten patients candidates to CRT (LV ejection fraction ≤35% and left bundle branch block) received a quadripolar LV lead. Four pacing configurations were tested: RV-S, SP-BS, MP-BS and CA-BS, where cathode and the anode were the same electrodes used as cathodes in MP-BS. QRS duration by 12-lead ECG was defined as the time from the earliest ventricular deflection until the return to the isoelectric line. Haemodynamic assessment by radial artery catheterization using Pressure Recording Analytical Method processed the following parameters: dP/dT max (mmHg/msec), systolic arterial pressure (aPsys, mmHg), diastolic arterial pressure (aPdia, mmHg), mean arterial pressure (aPmean, mmHg), Cardiac Index (CI, l/min/m2), Stroke Volume Index (SVI, ml/min/m2). Results dP/dT max and aPmean increased significantly from RV-S to SP-BS (mean dP/dT max 0,82±0,28 versus 0,87±0,29 mmHg/msec, p=0,02; mean aPmean 89±19 versus 93±20 mmHg, p=0,01), but not from RV-S to MP-BS. Comparing RV-S to CA-BS, only aPmean exhibited a significant increase (mean aPmean 89±19 versus 92±20 mmHg, p=0,01). There were no haemodynamic differences between SP-BS, MP-BS and CA-BS. QRS duration reduced significantly from RV-S (167±10 msec) to each biventricular stimulation (135±14 msec, p=0,0002 for SP-BS; 130±17 msec, p=0,0001 for MP-BS; 129±18 msec, p=0,0002 for CA-BS) and from SP-BS to MP-BS and CA-BS (p=0,03 for both), whereas there were no difference comparing MP-BS and CA-BS. Conclusions CA-LV stimulation is not superior to single-point CRT in terms of acute haemodynamic performance, whereas it reduces the duration of ventricular electrical activation, showing an electrohaemodynamic mismatch. Long-term studies are needed to evaluate if acute electrical benefits of CA stimulation can predict chronic benefits, in terms of reverse cardiac remodelling. Cathodic-anodal left ventricular capture Funding Acknowledgement Type of funding source: None
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Tulskiy, Gennadiy, Alena Tulskaya, Leonid Skatkov, Valeriy Gomozov, and Svetlana Deribo. "Electrochemical synthesis of hydrogen with depolarization of the anodic process." Electrochemical Energy Technology 2, no. 1 (January 13, 2016). http://dx.doi.org/10.1515/eetech-2016-0003.
Повний текст джерелаАнотація:
AbstractA new active composite coating for graphite gas diffusion electrode for hybrid sulfur cycle was proposed. The kinetics of oxidation of SO2 were studied on porous graphite anodes with different catalytic coatings. It was shown that the most efficient composite coating is based on activated carbon and platinum supported on graphite gas diffusion substrate. The voltage drop in the laboratory electrochemical cell was 1.3 V at a current density of 1000 A·m−2. This corresponds to a specific consumption of 3.1 kWh electric energy per 1 m3 of hydrogen.