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Kosuke Izutsu - One of the best experts on this subject based on the ideXlab platform.
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Further Study on the Component Related to Ion Solvation of the Liquid Junction Potential between Electrolyte Solutions in Different Solvents
Bulletin of the Chemical Society of Japan, 2013Co-Authors: Kosuke IzutsuAbstract:The liquid Junction Potential between electrolyte solutions in different solvents has been studied, paying attention to why the values of the component related to ion solvation are actually much sm...
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liquid Junction Potential between different solvents the component due to solvent solvent interactions is dipole Potential in nature
Bulletin of the Chemical Society of Japan, 2010Co-Authors: Kosuke IzutsuAbstract:The liquid Junction Potential between different solvents contains three components, i.e., component (a) due to electrolyte concentrations and ionic mobilities, component (b) due to the solvation of ions, and component (c) due to solvent-solvent interactions. The values of component (b) are actually much smaller than the values calculated from theoretical equations, but other researchers considered the equation to be valid and came to the conclusion that component (c) depended on electrolytes. From electrolyte-independent characteristics and others, we report here that component (c) is not the diffusion Potential but the dipole Potential.
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liquid Junction Potential between electrolyte solutions in different solvents some consideration on the component due to solvent solvent interactions
Bulletin of the Chemical Society of Japan, 2010Co-Authors: Kosuke IzutsuAbstract:The liquid Junction Potential between different solvents contains three components, i.e., (a) related to ionic concentrations and mobilities, (b) related to ion solvations, and (c) related to solvent-solvent interactions at the Junction. In order to understand the characteristics of component (c), we formerly introduced a model that the two solvents at the Junction directly interact each other as a Lewis acid and a Lewis base and some parts of the solvent molecules are oriented perpendicularly to the boundary. However, this direct-interaction model deviates from reality in that the actual Junction has a transition layer; its solvent composition gradually varies from that on one side to that on the other and its thickness expands with time, usually between 0.05 and 1 mm. In this report, we show that this direct-interaction model is applicable also in the presence of such transition layer. For this, we divide the transition layer in steps and get the total component (c) by summing up component (c) at each step. Here, the value at each step is obtained from the experimental results for component (c) at mixed solvent/mixed solvent Junctions. The extent of the solvent orientation at the boundary was also roughly estimated.
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Liquid Junction Potential between Electrolyte Solutions in Different Solvents Studied by Use of Mixed Solvent/Pure Solvent Junctions
Bulletin of the Chemical Society of Japan, 2008Co-Authors: Kosuke IzutsuAbstract:Of the three components of the liquid Junction Potential between electrolyte solutions in different solvents, the component due to the interaction between different solvents (component (c)) was stu...
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liquid Junction Potential between electrolyte solutions in different solvents studied by use of mixed solvent pure solvent Junctions
Bulletin of the Chemical Society of Japan, 2008Co-Authors: Kosuke IzutsuAbstract:Of the three components of the liquid Junction Potential between electrolyte solutions in different solvents, the component due to the interaction between different solvents (component (c)) was stu...
Yutaka Aoki - One of the best experts on this subject based on the ideXlab platform.
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Liquid Junction Potential between different solvents. A Junction with an alkali metal salt as electrolyte
Journal of Electroanalytical Chemistry, 1992Co-Authors: Kosuke Izutsu, Toshio Nakamura, Yutaka AokiAbstract:Abstract The characteristics of the three components of a liquid Junction Potential between different solvents were studied at a Junction with an alkali metal salt as the electrolyte. As for a Junction with a tetraalkylammonium salt as the electrolyte, the equation previously reported for component (a) was proved to be valid in many cases. Component (b) at H 2 O/organic solvent and MeOH/dipolar aprotic solvent Junctions also behaved similarly to that at a Junction with a tetraalkylammonium salt. At Junctions between aprotic solvents, however, lithium and sodium ions did not make an appreciable contribution to component (b), even when this was expected theoretically. This fact was found to be the cause of the apparently different behavior of component (c) in the case of salts of these metal ions. Thus component (c) can be considered to be almost independent of electrolyte species and concentrations, even when alkali metal salts are used as the electrolyte.
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Liquid Junction Potential between different solvents: A Junction with different electrolytes on the two sides
Journal of Electroanalytical Chemistry, 1992Co-Authors: Kosuke Izutsu, Mitsuo Muramatsu, Yutaka AokiAbstract:Abstract The characteristics of the liquid Junction Potential (ljp) between different solvents were investigated using different electrolytes on the two sides of a Junction, denoted as c 1 MX(S 1 )| c 2 NY(S 2 ). The ljp consists of three components, a, b and c, as reported previously. The calculated values of components a and b were obtained by numerical integration of the following equations, E j (a) = ( − RT / F )∫ S 1 S 2 {( t M – t X ) d ln a MX + ( t N – t Y ) d ln a NY} E j (b) = ( − 1 / F )∫ S 1 S 2 {itt M dμ°(M) – t X dμ°(X) + t N dμ°(N) – t Y dμ°(Y)} where t are the ionic transport numbers, a the electrolyte activities, and μ° the standard chemical Potentials. Linear variations in t, a and μ° at the interphase region were assumed. In a cell containing the above Junction, when the electrolyte concentrations, c 1 and c 2 , are varied, components a and b vary simultaneously. However, by making a proper correction for the actual values of component b, the emf variation corresponding to the actual variation in component a could be obtained. Thus, the above equation for component a was confirmed to be valid. The results also suggest that the previously reported method of estimation of component b is reasonable.
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a new method of estimation of the liquid Junction Potential between different solvents
Analytical Sciences, 1991Co-Authors: Kosuke Izutsu, Toshio Nakamura, Mitsuo Muramatsu, Yutaka AokiAbstract:Based on the experimental study of the three components of the liquid Junction Potential (LJP) between different solvents, a new method was developed for the estimation of the LJP. In the method, each of the three components was estimated separately from the others, and then they were summed up. The results obtained by this method agreed well with the results obtained by the conventional method.
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Liquid Junction Potential between different solvents: Component due to the differences in electrolyte concentrations and ionic mobilities
Journal of Electroanalytical Chemistry and Interfacial Electrochemistry, 1991Co-Authors: Kosuke Izutsu, Toshio Nakamura, Mitsuo Muramatsu, Yutaka AokiAbstract:Abstract Among the three components of the liquid Junction Potential at a Junction between different solvents, the component due to the differences in electrolyte concentrations (or activities) on the two sides of the Junction and the differences between the cationic and anionic mobilities was investigated. An equation was derived for the component at a Junction with the same electrolyte (MX) on the two sides, where t represents the ionic transport numbers and a the electrolyte activity. Linear variations of t and a were assumed at the interphase region of the Junction. The equation was confirmed experimentally to be approximately valid in many cases and may be used in estimating the component. In some cases, apparent deviations from the equation were observed. The deviations were attributed to the influence of electrolyte concentration, which caused partial decreases in the component due to the solvent-solvent interactions at the Junction. Some theoretical and experimental studies were also carried out for a Junction with different electrolytes (MX and NY) on the two sides,
Nobutaka Kobayashi - One of the best experts on this subject based on the ideXlab platform.
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Liquid Junction Potential between electrolyte solutions in different solvents: further study on the component related to ion solvation
Journal of Electroanalytical Chemistry, 2005Co-Authors: Kosuke Izutsu, Nobutaka KobayashiAbstract:Abstract The liquid Junction Potential (LJP) between electrolyte solutions in different solvents was studied by paying attention to the component related to ion solvation (component (b)). The actual variation in component (b) was obtained as the variation in corrected emfs (Ecorrected) of a cell and compared with the theoretical values (Ej(b)calc). New data for the Ecorrected − Ej(b)calc relation were obtained using amphiprotic ethylene glycol (EG) and formamide (FA) as solvent on one side of the Junctions. The Ecorrected − Ej(b)calc relations at miscible FA/ and EG/organic solvent Junctions were nearly linear with average slopes of 0.32 and 0.33, respectively, in contrast to 0.46 for H2O/organic solvents, 0.26 for MeOH/aprotic solvents, and ∼0 between two aprotic solvents. On the other hand, for partially miscible FA/ and EG/nitrobenze (NB), the slopes were 0.70 and 0.84, respectively, approaching unity with the decrease in miscibility. Some factors that may influence component (b) were pointed out and were discussed in detail by considering the phenomena at the Junctions. Additional data that support the method to estimate the actual values of component (b) by (slope) × Ej(b)calc were obtained. By appropriate corrections for component (b), the component due to solvent–solvent interactions was shown to be electrolyte-independent also at the Junctions containing EG, FA and N-methylformamide on one side.
K. Venkateswarlu - One of the best experts on this subject based on the ideXlab platform.
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Quantal evoked depolarizations underlying the excitatory Junction Potential of the guinea-pig isolated vas deferens.
The Journal of physiology, 1999Co-Authors: Rohit Manchanda, K. VenkateswarluAbstract:1. The effects of a putative gap Junction uncoupling agent, heptanol, on the intracellularly recorded Junction Potentials of the guinea-pig isolated vas deferens have been investigated. 2. After the stimulation-evoked excitatory Junction Potentials (EJPs) had been suppressed by heptanol (2.0 mM) to undetectable levels, a different pattern of evoked activity ensued. This consisted of transient depolarizations that were similar to EJPs in being stimulus locked and in occurring at a fixed latency, but differed from EJPs in that they occurred intermittently and had considerably briefer time courses. 3. Analysis of the amplitudes and temporal parameters of the rapid residual depolarizations revealed a close similarity with spontaneous EJPs (SEJPs). There was no statistically significant difference between the rise times, time constants of decay and durations of the rapid residual depolarizations and of SEJPs. 4. Selected evoked depolarizations were virtually identical to SEJPs occurring in the same cell. Evoked depolarizations of closely similar amplitude and time course also occurred, usually within a few stimuli of each other. 5. These depolarizations appear to represent the individual quantal depolarizations that normally underlie the EJP and are therefore termed 'quantal excitatory Junction Potentials' (QEJPs) to distinguish them from both EJPs and SEJPs. 6. We examined the possibility that heptanol revealed QEJPs by disrupting electrical coupling between cells in the smooth muscle syncytium. Heptanol (2.0 mM) had no effect on the amplitude distribution, time courses, or the frequency of occurrence of SEJPs. Intracellular input impedance (Rin) of smooth muscle cells was left unaltered by heptanol. 7. 'Cable' Potentials of the vas deferens, recorded using the partition stimulation method, also remained unchanged in the presence of heptanol. Thus, heptanol appeared not to modify syncytial electrical properties of the smooth muscle in any significant way. 8. Our observations show directly that the quantal depolarizations underlying the EJP in syncytial smooth muscle are SEJP-like events. However, no unequivocal statement can be made about the mechanism by which heptanol unmasks QEJPs from EJPs.
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Quantal evoked depolarizations underlying the excitatory Junction Potential of the guinea‐pig isolated vas deferens
The Journal of Physiology, 1999Co-Authors: Rohit Manchanda, K. VenkateswarluAbstract:1. The effects of a putative gap Junction uncoupling agent, heptanol, on the intracellularly recorded Junction Potentials of the guinea-pig isolated vas deferens have been investigated. 2. After the stimulation-evoked excitatory Junction Potentials (EJPs) had been suppressed by heptanol (2.0 mM) to undetectable levels, a different pattern of evoked activity ensued. This consisted of transient depolarizations that were similar to EJPs in being stimulus locked and in occurring at a fixed latency, but differed from EJPs in that they occurred intermittently and had considerably briefer time courses. 3. Analysis of the amplitudes and temporal parameters of the rapid residual depolarizations revealed a close similarity with spontaneous EJPs (SEJPs). There was no statistically significant difference between the rise times, time constants of decay and durations of the rapid residual depolarizations and of SEJPs. 4. Selected evoked depolarizations were virtually identical to SEJPs occurring in the same cell. Evoked depolarizations of closely similar amplitude and time course also occurred, usually within a few stimuli of each other. 5. These depolarizations appear to represent the individual quantal depolarizations that normally underlie the EJP and are therefore termed 'quantal excitatory Junction Potentials' (QEJPs) to distinguish them from both EJPs and SEJPs. 6. We examined the possibility that heptanol revealed QEJPs by disrupting electrical coupling between cells in the smooth muscle syncytium. Heptanol (2.0 mM) had no effect on the amplitude distribution, time courses, or the frequency of occurrence of SEJPs. Intracellular input impedance (Rin) of smooth muscle cells was left unaltered by heptanol. 7. 'Cable' Potentials of the vas deferens, recorded using the partition stimulation method, also remained unchanged in the presence of heptanol. Thus, heptanol appeared not to modify syncytial electrical properties of the smooth muscle in any significant way. 8. Our observations show directly that the quantal depolarizations underlying the EJP in syncytial smooth muscle are SEJP-like events. However, no unequivocal statement can be made about the mechanism by which heptanol unmasks QEJPs from EJPs.
Hikaru Suzuki - One of the best experts on this subject based on the ideXlab platform.
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Properties of the inhibitory Junction Potential in smooth muscle of the guinea-pig gastric fundus.
British journal of pharmacology, 1996Co-Authors: Naotomo Ohno, Yoshimichi Yamamoto, Lin Xue, Hikaru SuzukiAbstract:1. In circular smooth muscle of the guinea-pig gastric fundus, transmural nerve stimulation evoked a cholinergic excitatory Junction Potential (e.j.p.), and blockade of the e.j.p. by atropine revealed a non-adrenergic non-cholinergic (NANC) inhibitory Junction Potential (i.j.p.). 2. The amplitude of the e.j.p. was increased by apamin, suramin or NGnitro-L-arginine (L-NOARG), with no significant change in the membrane Potential. 3. The i.j.p. consisted of two components (fast and slow); apamin inhibited the former, nitroarginine inhibited the latter, and suramin inhibited both components. 4. Apamin inhibited the hyperpolarization produced by adenosine 5'-triphosphate (ATP) but not by vasoactive intestinal polypeptide (VIP). Suramin inhibited the hyperpolarization produced by VIP but not by ATP. The sodium nitroprusside (SNP)-induced hyperpolarization was not blocked by apamin or suramin. L-NOARG or tetrodotoxin did not inhibit the hyperpolarization produced by ATP, VIP or SNP. 5. The data did not support the hypothesis that ATP, VIP or nitric oxide (NO) is the main transmitter responsible for generation of the NANC i.j.p. in the fundus. 6. Actions of L-NOARG suggest that endogenous NO may be involved in Junctional transmission, mainly as an inhibitory modulator of cholinergic transmission.
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Suramin selectively inhibits the non-adrenergic non-cholinergic inhibitory Junction Potential in the guinea-pig stomach
European journal of pharmacology, 1993Co-Authors: Naotomo Ohno, Kaoru M. Ito, Yoshimichi Yamamoto, Hikaru SuzukiAbstract:Abstract In smooth muscle cells of the guinea-pig stomach fundus, transmural nerve stimulation evoked a cholinergic excitatory Junction Potential (e.j.p.) and, in the presence of atropine, a non-adrenergic non-cholinergic (NANC) inhibitory Junction Potential (i.j.p.). Suramin (> 10 −5 M), a putative inhibitor of the P 2 purinoceptor, enhanced the e.j.p. amplitude and inhibited the i.j.p., with no significant effect on the membrane Potential. Thus, a possible involvement of ATP in the generation of the NANC i.j.p. has to be considered.
