• Journal of the Korean Chemical Society
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• v.35 no.2
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• pp.128-134
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• 1991

Previous matrices of potassium ion selective electrodes are generally based on PVC. In this study, however, the electrode membrane was prepared with polyurethane matrix containing potassium tetraphenyl borate as sensing materials and D-18-Crown-6 and 2-nitrophenyl-n-alkylethers as solvent mediator. The average life time of the K$^+$-selective electrode based on polyurethane was 75 days which is significantly longer than PVC based one. The slope factor in linear dynamic range ($1{\times}10^{-1}\;{\sim}\;1{\times}10^{-4}$ M) was 52 mV/decade. The electrode has been successfully applied to find end point in potentiometric titration of K$^+$ with tetraphenyl borate solution in the sea water, even in the presence of several interfering cations$(NH^{4+},\;Na^{+},\;Li^{+},\;Ca^{2+},\;Mg^{2+},\;Cu^{2+}$).

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.3
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• pp.131-142
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• 2003

We have studied mutant forms of Kir2.1 in which an aspartate residue (D172), important for gating by intracellular polyamines, is replaced by one of three basic residues (Arg, Lys or His). Such channels are highly selective for $K^+$, but show inward rectification that is a shallow function of voltage compared with that found in wild type. This inward rectification occurs with a reduced affinity for spermine and persists in the absence of polyamines. Though the unitary current-voltage relation shows some inward rectification, it is insufficient to account for that seen under whole cell recording. Channels open and shut under single channel recording, and changes of $P_{open}$ appear to generate inward rectification. In D172H, the reduction in affinity for spermine is greater when His is protonated at low $pH_i$. The effective valency for spermine is reduced from $3.09{\pm}0.07$ in wild type to $1.95{\pm}0.09$ in D172H at $pH_i$ 6.3. In the presence of dual mutants of Kir2.1, where E224 is also replaced, spermine affinity becomes undetectable. However, channels still show inward rectification and open and shut under hyper- and depolarisation, respectively. We suggest that Kir2.1 channel are able to undergo conformation changes; these changes may be important physiologically in generating inward rectification, the normal parameters of which are set by the binding of polyamines such as spermine.

• Electrical & Electronic Materials
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• v.8 no.3
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• pp.332-339
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• 1995

In this paper, it was investigated the guided field intensity distribution of the channel in the silver & potassium ion-exchange glass-waveguide. The guided field intensity distribution analysis of ion-exchange glass-waveguide was based on the combination of the WKB dispersion relationship method with a Gaussian distribution function of refractive index profile and the Field Shadow method to the modeling of the channel waveguide. As the results of the channel waveguide modeling, it was represented 2-dimensional and 3-dimensional field distribution of ion-exchange glass waveguide.

• Toxicological Research
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• v.3 no.2
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• pp.89-96
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• 1987

To test the efficacies of thiosulfate in cyanide poisoning with or without oxygen, after the administration of sublethal dose of potassium cyanide, serial arterial blood samples were collected during 60 minutes in 15 rabbits. Cyanide ion concentrations were measured by Conway cell microdiffusion method, and arterial oxygen tensions were also observed. Comparison of elimination constants showed that arterial blood cyanide ion concentration decreased most rapidly in the thiosulfate with oxygen-administered group. The elimination of cyanide ion by the action of thiosulfate in acutely poisoned rabbit accelerated probably due to oxygen and elimination pattern seems to occur by first-order elimination kinetics.

• Bulletin of the Korean Chemical Society
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• v.29 no.3
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• pp.541-545
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• 2008

Stable molecular isomers were calculated for the azobenzene crown ether p-tert-butylcalix[4]arene (1) in the host and their alkali-metal-ion complexes. The structures of two distinct isomers (cis and trans) have been optimized using DFT B3LYP/6-31G(d,p) method. Trans isomer of 1 is found to be 11.69 kcal/mol more stable than cis analogue. For two different kinds of complexation mode, the alkali-metal-cation in the crown-ether moiety (exo) has much better complexation efficiency than in the benzene-rings (endo) pocket for both isomers of 1. Sodium ion has much better complexation efficiency than potassium ion in all kinds of complexation mode with host 1. The Na+ complexation efficiency of the trans-complex (1) in the exo-binding mode is 8.24 kcal/mol better than cis-exo analogue.

• Journal of Biosystems Engineering
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• v.32 no.5
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• pp.348-353
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• 2007

A solid state ion sensor module has been developed and evaluated for hydroponic nutrients analysis. The sensor module consisted of five ion-selective electrodes (ISE) fabricated by screen-printing technology. The electrochemical responses of ion sensors for nitrate, ammonium, potassium, calcium, and pH were measured with specially designed 7-channel low voltage signal transducers. The analytical characteristics of the sensors were comparable with those of conventional ISE sensors. The solid state ion sensors exhibit linear relationships over five concentration decades. Detection limit of the sensors were $5.6{\times}10^{-5}{\sim}1.6{\times}10^{-7}M$ depends on ions. Performance test results showed that relative errors of measured ion concentrations were less than 5% for $NO_3{^-},\;K^+,\;Ca^{2+}$ ion, and pH. The concentration of $NO_3{^-},\;NH_4{^+},\;K^+,\;Ca^{2+}$, and pH ion in standard solution and nutrient solutions could be determined by direct potentiometric measurements without any conditioning before measurements.

• Bulletin of the Korean Chemical Society
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• v.7 no.1
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• pp.66-69
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• 1986

The reaction of potassium trialkoxyborohydrides of varying steric requirements with lithium chloride in tetrahydrofuran(THF) was examined in detail to establish the generality of this synthesis of the corresponding lithium trialkoxyborohydrides. The metal ion exchange reaction between potassium triisopropoxyborohydride and lithium chloride in THF proceeded instantly at room temperature and the corresponding lithium salt was very stable toward disproportionation. However, for R = s-Bu, t-Bu and 2-methylcyclohexyl, with increasing steric requirement, the lithium derivatives were unstable and thus dissociated into $(RO)BH_3^-\;and\; (RO)_4B^-$. The stereoselectivity of lithium triisopropoxyborohydride(LIPBH) in the reduction of representative cyclic ketones was examined and compared with that of the potassium derivative.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.153-153
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• 2022

There is a growing need to develop ion sensors for agriculture. As a result, several technologies have been developed, such as colorimetry, spectrophotometry, and ion-selective electrode (ISE). Among them, ISE has some advantages compared to others. First, it does not require pre-treatment processes and expensive equipment. Second, it is possible for the portable detection system by introducing small-sized electrodes. Finally, real-time and multiple detections of several ions are pursued. It is well-known that N, P, and K nutrients are critical for crop growth. With the development of agriculture techniques, the importance of soil nutrient analysis has attracted much attention for cost-effective and eco-friendly agriculture. Among several issues, minimizing the use of fertilizers is significant through quantitative analysis of soil nutrients. As a result, it is highly important to analyze certain nutrients, such as N (ammonium ion, nitrate ion, nitrite ion), P (dihydrogen phosphate ion, monohydrogen phosphate ion), and K (potassium ion). Therefore, developing sensors for accurate analysis of soil nutrients is highly desired. n this study, several ISEs have been fabricated to detect N, P, and K. Their performance has been intensively studied, such as sensitivity, selectivity coefficient, and concentration range, and compared with commercialized ISEs. In addition, preliminary tests on the in-situ N, P, and K monitoring have been conducted inside the soil.

• Journal of Microbiology and Biotechnology
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• v.8 no.4
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• pp.301-304
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• 1998

Methylobacterium organophilum can use nitrogen in the form of ammonium ions ($($NH_4$)_2SO_4\;and\;NH_4Cl) and from nonammonium sources such as glycine, alanine, peptone, and yeast extract. When potassium was limited, significantly more PHB was produced when the ammonium ion was the nitrogen source rather than a nonammonium form. With ammonium, the amount of PHB produced was 0.50-0.53 g PHB/l or $52.0~53.2\%$ of the dry cell weight. If nitrogen was from a nonammonium source, the respective values were 0.04~0.06 g PHB/1 or $8.1~11.3\%$ of dry cell weight. When ammonium sulfate was the sole source of nitrogen under potassium-limited conditions, cell growth and PHB accumulation increased as the pH increased from 6.0 to 7.5. Cell growth and PHB amount at pH 7.5 were 2.50 g dry cell weight/1 and 1.40 g PHB/1, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.2
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• pp.168-174
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• 2006

We investigated field-effect ion-transport devices based on carbon nanotubes by using classical molecular dynamics simulations under applied external force fields, and we present model schematics that can be applied to the nanoscale data storage devices and unipolar ionic field-effect transistors. As the applied external force field is increased, potassium ions rapidly flow through the nanochannel. Under low external force fields, thermal fluctuations of the nanochannels affect tunneling of the potassium ions whereas the effects of thermal fluctuations are negligible under high external force fields. Since the electric current conductivity increases when potassium ions are inserted into fullerenes or carbon nanotubes, the field effect due to the gate, which can modify the position of the potassium ions, changes the tunneling current between the drain and the source.