• Molecules and Cells
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• v.45 no.11
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• pp.781-788
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• 2022

Proline plays a multifaceted role in protein synthesis, redox balance, cell fate regulation, brain development, and other cellular and physiological processes. Here, we focus our review on proline metabolism in neurons, highlighting the role of dysregulated proline metabolism in neuronal dysfunction and consequently neurological and psychiatric disorders. We will discuss the association between genetic and protein function of enzymes in the proline pathway and the development of neurological and psychiatric disorders. We will conclude with a potential mechanism of proline metabolism in neuronal function and mental health.

• Journal of the Korean Chemical Society
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• v.50 no.4
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• pp.307-314
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• 2006

The redox characteristics of 2-ketohydrazono-3-phenyl-5-substituted-2,3-dihydro-1,3,4-thiadiazoles and its derivatives (1a-h) has been investigated in nonaqueous solvents such as 1,2-dichloroethane (DCE), dichloromethane (DCM), acetonitrile (AN), tetrahydrofuran (THF), and dimethylsulfoxide (DMSO) containing 0.1 mol.dm-3 tetra n-butylammonium perchlorate (TBAP) as supporting electrolyte at platinum ectrode. Through controlled potential electrolysis, the oxidation and reduction products of the investigated compounds can be separated and indentified. The redox mechanism is suggested and proved. It was found that all the investigated compounds are oxidized in two irreversible one-electron processes following the well known pattern of EC-mechanism. On the other hand, these compounds are reduced in a single two electron or in a successive two one electron processes following the well known pattern of EEC-mechanism according to the nature of the substituent

• Proceedings of the KSEEG Conference
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• 2004.12a
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• pp.9-28
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• 2004

Concern about arsenic is increasing throughout the world, including areas of the United States. Elevated levels of arsenic above current drinking-water regulations in ground and surface water can be the result of purely natural phenomena, but often are due to anthropogenic activities, such as mining and agriculture. The current study correlates arsenic speciation in acid mine drainage and mining influenced water with the important water-chemistry properties Eh, pH, and iron(III) concentration. The results show that arsenic speciation is generally in equilibrium with iron chemistry in low pH AMD, which is often not the case in other natural-water matrices. High pH mine waters and groundwater do not 짐ways hold to the redox predictions as well as low pH AMD samples. The oxidation and precipitation of oxyhydroxides depletes iron from some systems, and this also affects arsenite and arsenate concentrations differently through sorption processes.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.90-101
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• 2004

The present trend of disposing treated sewage water by allowing it to infiltrate the soil brings a new dimension to environmental problems. It is therefore necessary to identify the chemicals likely to be present in treated sewage water. A soil column experiment was conducted to determine the behavior of chemical species in soil columns applied with secondary treated sewage water. To predict the behavior of chemical species, a multicomponent solute transport model that includes the biochemical redox process and cation exchange process was developed. The model computes changes in concentration over time caused by the processes of advection, dispersion, biochemical reactions and cation exchange reactions. The solute transport model was able to predict the behavior of the different chemical species. The model reproduced the sequential reduction reaction. To design the safe depth of plow layer where $NO_3^-$ is totally reduced, a numerical study of $NO_3^-$ leach was done and it was found out that the pore velocity and concentration of $CH_2O$ at the inject water was found to affect $NO_3^-$ reduction in the mobile pore water phase. It is revealed that the multicomponent solute transport model is useful to design the land treatment system for $NO_3^-$ removal from wastewater.

• Archives of Pharmacal Research
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• v.25 no.4
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• pp.485-492
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• 2002

The molecular fate of thyroglobulin (Tg) is controlled by oligomerization, a means of storing Tg at high concentrations, and deoligomerization. The oligomerization of bovine Tg are intermolecular reactions that occur through oxidative processes, such as disulfide and dityrosine formation, as well as isopeptide formation; disulfide formation is primarily responsible for Tg oligomerization. Here, the protein disulfide isomerase (PDI) and/or peroxidase-induced oligomerization of unfolded thyroglobulins, which were prepared by treating bovine Tg with heat, urea or thiol/urea, was investigated using SDS-PAGE analyses. In addition, the enzymatic oligomerization was compared with non-enzymatic oligomerization. The thermally-induced oilgomerization of Tg, dependent on glutathione redox state, was affected by the ionic strength or the presence of a surfactant. Meanwhile, PDI-catalyzed oligomerization, time and pH-dependent, was the most remarkable with unfolded/reduced Tg, which was prepared from a treatment with urea/DTT, while the thermally-unfolded Tg was less sensitive. Similarly, the oligomerization of unfolded/reduced Tg was also mediated by peroxidase. However, PDI showed no remarkable effect on the peroxidase-mediated oligomerization of either the unfolded or unfolded/reduced Tg. Additionally, the reductive deoligomerization of oligomeric Tg was exerted by PDI in an excessively reducing state. Based on these results, it is proposed that PDI catalyzes the oligomerization of Tg through the disulfide linkage and its deoligomerization in the molecular fate, and this process may require a specific molecular form of Tg, optimally unfolded/reduced, in a proper redox state.

• Journal of Electrochemical Science and Technology
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• v.7 no.1
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• pp.82-89
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• 2016

In this work, a ruthenium dioxide electrode has been prepared by thermal decomposition at 400 ℃ then used for the oxidation of commercial amoxicillin. The physical characterization showed that RuO₂ electrode presents a mud cracked structure. Its electrochemical characterization has revealed an increase of the voltammetric charge in acid electrolyte compared to neutral electrolyte indicating the importance of protons in its surface redox processes. The voltammetric study of the oxidation of amoxicillin has been investigated. It has been obtained that the oxidation of amoxicillin is controlled by both adsorption and diffusion processes. Moreover, the oxidation of amoxicillin occurs via direct and indirect processes in free or electrolyte containing chlorides. Through preparative electrolysis, enhancement of amoxicillin oxidation was observed in the presence of chloride where the amoxicillin degradation yield reached more than 50 % compared to less than 5% in the absence of chlorides. Spectrophotometric investigations have revealed the degradation of intermediates absorbing at 350 nm.

• Economic and Environmental Geology
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• v.39 no.2 s.177
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• pp.151-162
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• 2006

Characteristics and changes of groundwater qualify were investigated in a riverbank filtration area at Daesan-myeon, Changwon City, Korea. The total dissolved solids (TDS) in groundwater samples collected in October were much less than that in March, indicating the mixing with recharged water from precipitation, as well as the changes of dissolved oxygen profiles at monitoring wells from March to October. Redox processes at depths appeared to trigger Fe and Mn contamination of groundwater in riverbank deposits. Amorphous oxyhydroxides md carbonate minerals such as $MnCO_3$ were probably the reactive phases for dissolved Fe and Mn, respectively. Groundwater contamination by nitrate-nitrogen $(NO_3-N)$ was controlled by the redox processes and subsequent denitrification at the sampled depths. Distribution of $NO_3-N$ concentrations at monitoring wells suggested that the nitrate contaminants were originated from agricultural facilities on the riverbank deposits. Some of monitoring wells, DS-2, D-2, DS-3, SJ-1, and SJ-3, were only partially penetrated into the sand/gravel aquifer, and subsequently, could not fully function to detect the water quality changes for the pumping wells. Proper measures, with regulating agricultural activities in the riverbank deposits, should be carried out to prevent groundwater contamination of the riverbank filtration area.

• Journal of the Korean Chemical Society
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• v.33 no.2
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• pp.192-202
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• 1989

Tetradentate schiff bases cabalt (II) complexes; Co(SED) and Co(ο-BSDT) were synthesized and these complexes allowed to reaction with dry oxygen to form oxygen adduct cobalt(III) complexes such as $[Co(o-BSDT)(DMSO)]_2O_2,\;[Co(SED)(Py)]_2O_2\;and\;[Co(o-BSDT)(Py)]_2O_2$ in DMSO and pyridine solutions. It has been found that the oxygen adduct cobalt(III) complexes have hexacoordinated octahedral configuration with tetradentate schiff base cobalt(II), DMSO or pyridine and oxygen, and the mole ratio of oxygen to cobalt(II) complexes are 1:2. The redox processes, were investigated for Co(SEDT) and Co(ο-BSD) complexes in 0.1M TEAP-DMSO and 0.1M TEAP-pyridine by cyclic voltammetry with glassy carbon electrode. As a result the redox processes of Co(II)/Co(III) and Co(II)/Co(I) found to be reversible or quasi-reversible for non uptake oxygen complexes but oxygen adduct complexes found to be irreversible processes and reaction processes of oxygen for oxygen adduct complexes are quasi-reversible process, the potential range was $E_{pc}=-0.85{\sim}-1.19V\;and\;E_{pa}=-0.74{\sim}-0.89V$.

• Journal of Electrochemical Science and Technology
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• v.11 no.2
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• pp.187-194
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• 2020

Two types of sodium cobalt pyrophosphates, triclinic Na_3.12Co_2.44(P₂O₇)₂ and orthorhombic Na₂CoP₂O₇, are compared as high-voltage cathode materials for Na-ion batteries. Na₂CoP₂O₇ shows no electrochemical activity, delivering negligible capacity. In contrast, Na_3.12Co_2.44(P₂O₇)₂ exhibits good electrochemical performance, such as high redox potential at ca. 4.3 V (vs. Na/Na⁺) and stable capacity retention over 50 cycles, although Na_3.12Co_2.44(P₂O₇)₂ delivered approximately 40 mA h g^-1. This is attributed to the fact that Na₂CoP₂O₇ (~3.1 Å) has smaller diffusion channel size than Na_3.12Co_2.44(P₂O₇)₂ (~4.2 Å). Moreover, the electrochemical performance of Na_3.12Co_2.44(P₂O₇)₂ is examined using Na cells and Li cells. The overpotential of Na cells is smaller than that of Li cells. This is due to the fact that Na_3.12Co_2.44(P₂O₇)₂ has a smaller charge transfer resistance and higher diffusivity for Na⁺ ions than Li⁺ ions. This implies that the large channel size of Na_3.12Co_2.44(P₂O₇)₂ is more appropriate for Na⁺ ions than Li⁺ ions. Therefore, Na_3.12Co_2.44(P₂O₇)₂ is considered a promising high-voltage cathode material for Na-ion batteries, if new electrolytes, which are stable above 4.5 V vs. Na/Na⁺, are introduced.

• Journal of the Korean Chemical Society
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• v.34 no.1
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• pp.51-62
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• 1990

Pentadentate Schiff base cobalt(II) complexes; Co(II)(Sal-DET) and Co(II)(Sal-DPT) were synthesized and these complexes were allowed to react with dry to form oxygen adducts of cobalt(II) complexes such as [Co(III)(Sal-DET)]$_2O_2$ and [Co(III)(DPT)]$_2O_2$ in aprotic solvents. These complexes have been identified by IR spectra, TGA, DSC, magnetic susceptibility measurements, and elemental analysis. It has been found that the oxygen adadduct complexes of $\mu$-peroxo type have hexaccordinated octahedral configuration with pentadentate schiff base cobalt(II) and oxygen, but the mole ratio of oxygen to cobalt(III) complexes of first step for oxygen adduct formation reaction of cobalt(II) complexes in aprotic solvents are 1:1. The redox reaction processes of Co(II)(Sal-DET), Co(II)(Sal-DPT), and oxygen adduct of cobalt(II) complexes were investigated by cyclic voltammetry and DPP method with glassy carbon electrode in 0.1M TEAP-DMSO and 0.1M TEAP-pyridine. As a result the reduction reaction processes of Co(III)/Co(II) and Co(II)/Co(I) for cobalt(II) complexes and oxygen adducts of cobalt(II) complexes are two irreversible steps of one eletron process, and reaction processes of oxygen for oxygen adducts complexes were quasireversible and redox range of potential was $E_{pc}$ = -0.97V∼-0.86V and $E_{pa}$ = -0.87V ∼ 0.64V.