CYSTINE AS AN ADDITION AGENT IN THE ELECTRODEPOSITION OF COPPER

1955 ◽  
Vol 33 (5) ◽  
pp. 961-970 ◽  
Author(s):  
A. J. Sukava ◽  
C. A. Winkler
Keyword(s):  
Steady State ◽  
Current Density ◽  
Copper Complex ◽  
Copper Complexes ◽  
Concentration Polarization ◽  
Hydrogen Ion ◽  
Addition Agent ◽  
Agent Behavior ◽  
Low Concentrations ◽  
Sulphate Electrolyte

The steady state polarization of 100 mv. in acid copper sulphate electrolyte, at 2 amp./dm.2, appears to consist of 45 to 50 mv. activation overpotential to deposit aquo–copper complexes, 20 to 25 mv. concentration polarization, and about 30 mv. polarization due to hydrogen ion interference. The presence of cystine in the electrolyte gave rise to polarization–time curves similar to those observed previously with gelatine. The increase of polarization caused by cystine appears to be due to an obstructive effect of adsorbed cystine (or its copper complex), together with an increase of concentration polarization. Cystine alone probably does not affect the activation overpotential. Addition of sufficient chloride virtually eliminated the polarization due to obstruction by cystine, possibly by acting as an electron bridge or by forming more readily dischargeable chloro–cystine–copper complexes. Chloride also eliminated the increment in concentration polarization caused by cystine. Attainment of a minimum total steady state polarization of about 40 mv. in the presence of cystine and chloride appeared to reflect an increase of surface, hence a decrease of true current density with time of deposition. The addition agent behavior of methionine was, in most respects, similar to that of cystine. The behavior of thiourea at low concentrations appeared to be complicated, but the effects of chloride were similar to those observed with gelatine.

EFFECT OF GELATIN ON THE CHANGES IN INITIAL CATHODE POLARIZATION DURING ELECTRODEPOSITION OF COPPER

1954 ◽  
Vol 32 (6) ◽  
pp. 581-590 ◽  
Author(s):  
B. I. Parsons ◽  
C. A. Winkler
Keyword(s):  
Steady State ◽  
Current Density ◽  
Copper Sulphate ◽  
Chloride Concentration ◽  
High Current ◽  
Concentration Increase ◽  
Addition Agent ◽  
Cathode Polarization ◽  
Current Densities ◽  
Gelatin Concentration

In the absence of addition agent, the cathode polarization during initial electrolysis of copper from a solution of acid copper sulphate rose almost instantaneously from zero to approximately the steady state polarization. When gelatin was present in the electrolyte, the polarization generally increased to a maximum, Pmax, (in time tmax) then decreased to a minimum, Pmin, (in-time tmin) beyond which it increased to the steady state value, Ps. Generally, Pmax increased to a steady value with an increase in the time, T0, the electrode was in contact with the electrolyte before electrolysis was begun. At low, moderate, and high current densities respectively, tmax increased continuously, passed through a maximum, and decreased continuously with T0.The behavior of tmin approximately paralleled that of tmax. The polarization was linear in the logarithm of the current density; tmax and tmin decreased with increase in current density. The polarization values increased and tmax decreased, with increase in gelatin concentration. Increase of temperature had approximately the same effect as decrease in current density. With both chloride and gelatin present, Pmax was practically independent of T0 and chloride concentration, while Pmin and Ps showed minimum values at about 2 mgm./l. chloride.

DEPOLARIZATION BY MERCAPTOACETIC ACID DURING ELECTRODEPOSITION OF COPPER

1956 ◽  
Vol 34 (2) ◽  
pp. 128-132 ◽  
Author(s):  
A. J. Sukava ◽  
C. A. Winkler
Keyword(s):  
Surface Area ◽  
Current Density ◽  
Copper Complex ◽  
Copper Sulphate ◽  
Mercaptoacetic Acid ◽  
Surface Roughening ◽  
Cathode Polarization ◽  
Sulphate Electrolyte ◽  
Consequent Increase

Mercaptoacetic acid (MAA) in acid copper sulphate electrolyte decreased the cathode polarization throughout the course of electrolysis at all concentrations up to 20 mgm./liter. Addition of small amounts of chloride caused further depolarization. When present together with cystine, MAA showed an independence of action. The depolarization caused by MAA was ascribed to a decreased activation overpotential due to substitution of a more readily dischargeable MAA–copper complex for the aquo–copper complex. The additional depolarization due to chloride was ascribed to formation of a still more readily dischargeable chloro–MAA–copper complex. The depolarization in both cases increased with time during prolonged electrolysis, apparently due to surface roughening with, presumably, a consequent increase in surface area and decrease in true current density.

GLUTAMIC ACID AS AN ADDITION AGENT IN THE ELECTRODEPOSITION OF COPPER

1954 ◽  
Vol 32 (10) ◽  
pp. 931-940 ◽  
Author(s):  
S. Adamek ◽  
C. A. Winkler
Keyword(s):  
Steady State ◽  
Glutamic Acid ◽  
Induction Period ◽  
Sulphuric Acid ◽  
Acid Concentration ◽  
Concentration Polarization ◽  
The Other ◽  
Addition Agent ◽  
Polarization Level ◽  
Sulphuric Acid Concentration

The polarization–time curves obtained in the presence of glutamic acid generally showed two distinct polarization levels, one corresponding to an induction period following an initial rapid increase of polarization from the standard surface value, and the other corresponding to a steady state period following a second rapid increase of polarization. The polarization at both levels increased with increase of glutamic acid concentration and decreased with increase of sulphuric acid concentration in the electrolyte. In general, the induction period increased, and eventually became irreproducible, with increased sulphuric acid and copper sulphate concentrations, decreased glutamic acid concentration, decreased current density, increased temperature, and addition of chloride. Addition of sufficient chloride prolonged the induction period indefinitely at a polarization level corresponding to the presence of chloride alone. Following the induction period, the concentration polarization increased with glutamic acid concentration and was considerably higher than the value obtained during the induction period. Addition of chloride decreased the concentration polarization.

scholarly journals Transient Current Density in a Pair of Long Parallel Conductors

2021 ◽  
Vol 11 (15) ◽  
pp. 6920
Author(s):  
Oldřich Coufal
Keyword(s):  
Steady State ◽  
Cross Section ◽  
Current Density ◽  
Circular Cross Section ◽  
Transient Current ◽  
Constant Current ◽  
Voltage Source ◽  
Sinusoidal Voltage ◽  
Steady State Current ◽  
Maximum Current

Two infinitely long parallel conductors of arbitrary cross section connected to a voltage source form a loop. If the source voltage depends on time, then due to induction there is no constant current density in the loop conductors. It is only recently that a method has been published for accurately calculating current density in a group of long parallel conductors. The method has thus far been applied to the calculation of steady-state current density in a loop connected to a sinusoidal voltage source. In the present article, the method is used for an accurate calculation of transient current using transient current density. The transient current is analysed when connecting and short-circuiting the sources of sinusoidal, constant and sawtooth voltages. For circular cross section conductors, the dependences of maximum current density, maximum current and the time of achieving steady state on the source frequency, the distance of the conductors and their resistivity when connecting the source of sinusoidal voltage are examined.

Analysis of plasma equilibrium based on orbit-driven current density profile in steady-state plasma on QUEST

2016 ◽  
Vol 109-111 ◽  
pp. 1528-1533 ◽  
Author(s):  
K. Nakamura ◽  
M.M. Alam ◽  
Y.Z. Jiang ◽  
O. Mitarai ◽  
K. Kurihara ◽  
...  
Keyword(s):  
Steady State ◽  
Density Profile ◽  
Current Density ◽  
Plasma Equilibrium ◽  
Current Density Profile ◽  
State Plasma

Gadolinium Reduces AMPA Receptor Desensitization and Deactivation in Hippocampal Neurons

2001 ◽  
Vol 86 (1) ◽  
pp. 173-182 ◽  
Author(s):  
Saobo Lei ◽  
John F. MacDonald
Keyword(s):  
Steady State ◽  
Ampa Receptor ◽  
Hippocampal Neurons ◽  
Time Course ◽  
Single Channel ◽  
Trivalent Cation ◽  
Receptor Desensitization ◽  
Whole Cell ◽  
Low Concentrations ◽  
Cultured Hippocampal Neurons

The actions of the trivalent cation Gd3+ on whole cell AMPA receptor-mediated currents were studied in isolated hippocampal neurons, in nucleated or outside-out patches taken from cultured hippocampal neurons, and on miniature excitatory postsynaptic currents (mEPSCs) recorded in cultured hippocampal neurons. Glutamate, AMPA, or kainate was employed to activate AMPA receptors. Applications of relatively low concentrations of Gd3+ (0.1–10 μM) substantially enhanced steady-state whole cell glutamate and kainate-evoked currents without altering peak currents, suggesting that desensitization was reduced. However, higher concentrations (>30 μM) depressed steady-state currents, indicating an underlying inhibition of channel activity. Lower concentrations of Gd3+also increased the potency of peak glutamate-evoked currents without altering that of steady-state currents. An ultrafast perfusion system and nucleated patches were then used to better resolve peak glutamate-evoked currents. Low concentrations of Gd3+ reduced peak currents, enhanced steady-state currents, and slowed the onset of desensitization, providing further evidence that this cation reduces desensitization. In the presence of cyclothiazide, a compound that blocks desensitization, a low concentration Gd3+ inhibited both peak and steady-state currents, indicating that Gd3+ both reduces desensitization and inhibits these currents. Gd3+ reduced the probability of channel opening at the peak of the currents but did not alter the single channel conductance calculated using nonstationary variance analysis. Recovery from desensitization was enhanced, and glutamate-evoked current activation and deactivation were slowed by Gd3+. The Gd3+-induced reduction in desensitization did not require the presence of the GluR2 subunit as this effect was seen in hippocampal neurons from GluR2 null-mutant mice. Gd3+ reduced the time course of decay of mEPSCs perhaps as a consequence of its slowing of AMPA receptor deactivation although an increase in the frequency of mEPSCs also suggested enhanced presynaptic release of transmitter. These results demonstrate that Gd3+ potently reduces AMPA receptor desensitization and mimics a number of the properties of the positive modulators of AMPA receptor desensitization such as cyclothiazide.

THE EFFECT OF ADDITION AGENTS ON CATHODE POLARIZATION DURING ELECTRODEPOSITION OF COPPER AT SINGLE CRYSTAL COPPER CATHODES

1955 ◽  
Vol 33 (12) ◽  
pp. 1756-1767
Author(s):  
K. Ekler ◽  
C. A. Winkler
Keyword(s):  
Steady State ◽  
Single Crystal ◽  
Single Crystals ◽  
Linear Relation ◽  
Crystal Orientation ◽  
Chloride Ion ◽  
Addition Agent ◽  
Cathode Polarization ◽  
Single Crystal Copper ◽  
Copper Single Crystals

The polarization–time relations for the initial (Pi), maximum (Pmax), and pseudo-steady-state (Ps) polarizations on copper single crystals in the absence and presence of gelatin and gelatin plus chloride ion were found to depend upon crystal orientation. The Pi and Pmax in the absence of gelatin, the Pi in its presence, and the static potentials were all similarly related to the reticular density. The Pi increased, and the time to maximum polarization (tmax) decreased, with increase of current density; the relations between these quantities showed marked differences for the different crystals. The variation with reticular density of Pi and Pmax in the absence of addition agents and of Pi in its presence probably represents differences in activation overpotential at the various crystal faces. The adsorption of gelatin on different crystal faces was also found to be markedly different. Polarization in the presence of gelatin was decreased by small amounts of chloride ion; a linear relation for all the crystals used was obtained by plotting the increase in polarization caused by gelatin against the decrease caused by 2 mgm./liter chloride ion in the presence of gelatin. In the absence of addition agent, change of acid concentration from 50 to 200 gm./liter had no effect on Pi and addition of chloride ion had no effect on Ps at single crystal cathodes.

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