• Journal of Life Science
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• v.20 no.12
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• pp.1777-1783
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• 2010

Plants generate reactive oxygen species (ROS) as a by-product of normal aerobic metabolism or when exposed to a variety of stress conditions, which can cause widespread damage to biological macromolecules. To protect themselves from oxidative stress, plant cells are equipped with a wide range of antioxidant proteins. However, the detailed reaction mechanisms of these are still unknown. Peroxiredoxins (Prxs) are ubiquitous thiol-containing antioxidants that reduce hydrogen peroxide with an N-terminal cysteine. The active-site cysteine of peroxiredoxins is selectively oxidized to cysteine sulfinic acid during catalysis, which leads to inactivation of peroxidase activity. This oxidation was thought to be irreversible. Recently identified small protein sulphiredoxin (Srx1), which is conserved in higher eukaryotes, reduces cysteine.sulphinic acid in yeast peroxiredoxin. Srx1 is highly induced by $H_2O_2$-treatment and the deletion of its gene causes decreased yeast tolerance to $H_2O_2$, which suggest its involvement in the metabolism of oxidants. Moreover, Srx1 is required for heat shock and oxidative stress induced functional, as well as conformational switch of yeast cytosolic peroxiredoxins. This change enhances protein stability and peroxidase activity, indicating that Srx1 plays a crucial role in peroxiredoxin stability and its regulation mechanism. Thus, the understanding of the molecular basis of Srx1 and its regulation is critical for revealing the mechanism of peroxiredoxin action. We postulate here that Srx1 is involved in dealing with oxidative stress via controlling peroxiredoxin recycling in Arabidopsis. This review article thus will be describing the functions of Prxs and Srx in Arabidopsis thaliana. There will be a special focus on the possible role of Srx1 in interacting with and reducing hyperoxidized Cys-sulphenic acid of Prxs.

• Journal of the Mineralogical Society of Korea
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• v.5 no.2
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• pp.72-78
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• 1992

The Earth outer core accomodates moderately considerable amount of lighter elements than pure iron itself. Hydrogen is one of the possible candidates of minor constituents in the outer core. It would be worth while to extend for the pressure effect on the solubility of hydrogen in the metal-hydrides including iron hydride. In view of hydrogen being one of the potential substitutes for petroleum, searching a more efficient way for storing hydrogen in the form of hydrides is of considerable value. For two purposes, $TiH_2$was selected among lot of hydrides for its characteristics under pressure and temperature. There have been two kinds of experiment carried out on $TiH_2$ under different experimental conditions. As one of these attempts, polycrystalline $TiH_2$ was loaded up to 15 GPa stepwise at the constant temperature 500${\circ}$ using a piston-cylinder diamond anvil cell equipped with a miniature furnace of an electric power supply. The X-ra diffraction technique was employed on the quenched samples after the simultaneous high pressure and temperature treatments. During these high pressure-temperature runs, and irreversible phase of $TiH_2$ has been observed at the pressures higher than 11.3 GPa, which would be assigned to the orthorhombic crystal system as one of the new phase(s) of $TiH_2$. Molar volume change on this phase transition is ∼10%.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.1
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• pp.31-36
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• 2008

This work was performed to evaluate the effect of membrane material and structure on fouling in a submerged membrane bioreactor(MBR). Three types of microfiltration membranes with the same pore size of 0.1 $\mu$m but different materials, polytetrafluoroethylene (PTFE), polycarbonate(PCTE) and polyester(PETE), were used. While PETE membrane exhibited the most rapid flux decline throughout the operation, PCTE and PTFE had a similar tendency with regard to permeability. Difference in permeability between PETE and the other membranes gradually decreased with time, which was probably due to chemical cleaning. The higher TOC rejection of PETE membrane could be attributable to its faster fouling, resulting from a larger amount of foulants to get attached to the membrane in a shorter time. DOC fractionation using a DAX-8 resin showed that the composition of each fraction between the supernatant and permeates did not change significantly with operation time, indicating that membrane hydrophilicity/hydrophobicity was not a dominant factor affecting to MBR fouling in this study. Compared to other membranes, the fouling of PETE membrane was more influenced by pore clogging (irreversible fouling), which would probably contribute to a higher organic rejection of the PETE membrane.

• Korean Chemical Engineering Research
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• v.58 no.3
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• pp.458-465
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• 2020

Isotherms, kinetics and thermodynamic properties for adsorption of acid fuchsin (AF) dye by activated carbon were carried out using variables such as dose of adsorbent, pH, initial concentration and contact time and temperature. The effect of pH on adsorption of AF showed a bathtub with high adsorption percentage in acidic (pH 8). Isothermal adsorption data were fitted to the Freundlich, Langmuir, and Dubinin-Radushkevich isotherm models. Freundlich isothem model showed the highest agreement and confirmed that the adsorption mechanism was multilayer adsorption. It was found that adsorption capacity increased with increasing temperature. Freundlich's separation factor showed that this adsorption process was an favorable treatment process. Estimated adsorption energy by Dubinin-Radushkevich isotherm model indicated that the adsorption of AF by activated carbon is a physical adsorption. Adsorption kinetics was found to follow the pseudo-second-order kinetic model. Surface diffusion at adsorption site was evaluated as a rate controlling step by the intraparticle diffusion model. Thermodynamic parameters such as activation energy, Gibbs free energy, enthalpy entropy and isosteric heat of adsorption were investigated. The activation energy and enthalpy change of the adsorption process were 21.19 kJ / mol and 23.05 kJ / mol, respectively. Gibbs free energy was found that the adsorption reaction became more spontaneously with increasing temperature. Positive entropy was indicated that this process was irreversible. The isosteric heat of adsorption was indicated physical adsorption in nature.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.267-275
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• 1997

$ZrO_2$ Powder was Prepared by sol-gel process and the adsorption characteristic of cobalt($Co^{2+}$) by $ZrO_2$ adsorbent in high-temperature water was investigated using batch adsorption experiment with a stirred autoclave. The prepared $ZrO_2$ was calcined at $600{\sim}1400^{\circ}C$ and analyzed by X-ray diffractometry, SEM, BET surface area, FT-IR and TG-DTA measurement. The tetragonal Phase of $ZrO_2$ is produced $480^{\circ}C$ from amorphous gel at temperature $480^{\circ}C$. Both tetragonal and monoclinic phase of $ZrO_2$ exist at temperature between $600^{\circ}C$ and $1000^{\circ}C$. At temperature $1200^{\circ}C$, tetragonal to monoclinic phase trasition is occurred. The $Co^{2+}$ adsorption capacity of $ZrO_2$ calcined at $600^{\circ}C$ for 4 hours is 0.16 meq $Co^{2+}/g$ adsorbent in the high temperature at $250^{\circ}C$. The adsorption of $Co^{2+}$ on the $ZrO_2$ adsorbent is irreversible endothermic in the temperature range ($125-175^{\circ}C$). The standard enthalpy change (${\Delta}H^{\circ}$) of $ZrO_2$ calcined at $600^{\circ}C$ for 4 hours is 18 kJ/gmol.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.14 no.2
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• pp.123-134
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• 2014

Recent advances in the diagnosis and treatment of inborn errors of metabolism (IEM) have improved substantially the prognosis of many of these diseases, if diagnosed early enough before irreversible damage occurs. Diseases of inborn errors of metabolism are so diverse over several hundred disease up to now and may be several thousand in near future, and these diversities of IEMs make clinicians embarassed. The signs of neurological dysfunctions of many IEMs manifesting in the neonatal period is very nonspecific, such as poor feeding, poor sucking, apnea or tachypnea, vomiting, hypertonia, hypotonia, seizure, letharginess, consciousness change and coma. But after neonatal period, the signs of neurological deficits become specific and localized. The results of routine basal laboratory tests such as metabolic acidosis, hyperammonemia, lactic acidemia, ketonemia or hyperuricemia can give very important clinical clues for the diagnosis of IEMs. Even no abnormal findings on routine laboratory test could be very important clue for NKH, sulfite oxidase deficiency and peroxisomal disorders. These various clinical manifestations of these diverse diseases can be categorized and summarized. This makes it essential that the practicing clinicians be familiar with the clinical presentations and symptomatic and systematic approaches of these disorders. Characteristic clinical presentations, methods of symptomatic and systematic approach and typing of various disorders is discussed in this review.

• Journal of the Korean Chemical Society
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• v.34 no.6
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• pp.561-568
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• 1990

Voltammetric behavior of some light lanthanide ions (La$^{3+}$, Pr$^{3+}$, Nd$^{3+}$, Sm$^{3+}$, and Eu$^{3+}$) in various supporting electrolytes has been investigated by several electrochemical techniques. The peak potentials and the peak currents, their dependency on the concentration, temperature and pH effects, the reversibility of the electrode reactions are described. The reduction of La$^{3+}$, Pr$^{3+}$ and Nd$^{3+}$ in 0.1 M lithium chloride proceeds by a three-electron change directly to the metallic state (Ln$^{3+}$ ＋ 3e- → Ln$^0$) and charge transfer is totally irreversible. However, the reduction of Sm$^{3+}$ in 0.1 M tetramethylammonium iodide and Eu$^{3+}$ in 0.1 M lithium chloride proceeds in two stages (Ln$^{3+}$ ＋ e- → Ln$^{2+}$ and Ln$^{2+}$ ＋ 2e- → Ln$^0$). At pH values lower than ca.4 the hydrated lanthanide species (Ln(OH)$^{2+}$) reduced before the lanthanide ions (Ln$^{3+}$) due to the catalytic effect of hydrogen ions, and peak current increase with in the order Eu$^{3+}$ < Sm$^{3+}$ < Nd$^{3+}$ < Pr$^{3+}$ < La$^{3+}$ in differential pulse polarography. Some representative plots of $i_{pc}V^{-1/2} (proportional to current function) vs. V show considerable influence of hydrogen ion/lanthanide ion concentration in cyclic voltammetry. It is shown that a reaction of lanthanide ions with proton and/or water and catalytic reaction is enhanced at lower pH and at decreased lanthanide ion concentration.

• Journal of Chest Surgery
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• v.18 no.4
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• pp.732-739
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• 1985

This study was experimentally undertaken to evaluate the effect of the coronary vasodilator-mixed cardioplegic solution on myocardial protection during prolonged aortic cross-clamping. The dogs were divided into two groups: control group A[received hypothermic cardioplegic solution without any additive coronary vasodilator], and comparing group 8[received hypothermic cardioplegic solution, mixed with various coronary vasodilators and Inderal]. Group A further was divided into two subgroups: subgroup A-1[ischemic time, 90 minutes], and subgroup A-2 [ischemic time, 240 minutes]. Group B further was divided into five subgroups: subgroup B-1 [received papaverine mixed hypothermic cardioplegic solution], subgroup B-2[received nitroglycerin mixed hypothermic cardioplegic solution], subgroup B-3 [received nitroprusside mixed hypothermic cardioplegic solution, subgroup B-4[received hydralazine mixed hypothermic cardioplegic solution], and subgroup B-5 [received inderal mixed hypothermic cardioplegic solution]. The specimens from all of the subgroups were studied by electron microscopic examination. The specimens of subgroups [B-l, B-2 8-3, and B-4], received coronary vasodilators mixed hypothermic cardioplegic solutions, were also compared by methylene blue induced staining of the myocardium and coronary vessels. The results obtained were as followings: l. On electron microscopic examination, all of the specimens, including subgroup A-2, showed no irreversible change of the myocardium. But the best result was obtained from the subgroup B-l, treated by papaverine mixed hypothermic cardioplegic solution. The subgroup B-2, treated by nitroglycerin, was next. And the subgroup B-5, treated by Inderal, was agreeable, comparing the electron microscopic finding with control group in the effect of myocardial protection. 2. The distribution in the myocardium of cardioplegic solution was demonstrated with the aid of methylene blue staining in the subgroups of B-l, B-2, B-3, and B-4, and they were the groups treated by papaverine, nitroglycerin, nitroprusside, and hydralazine in their grouping order. The best result was obtained from the subgroup B-1 [papaverine]. The subgroup B-2 [nitroglycerin] was next. The subgroup B-3 [nitroprusside] was moderate in finding of the colorization. The subgroup B-4 [hydralazine] was the poorest in the distribution of the cardioplegic solution in the myocardium. From these results, it appeared that myocardial protection during ischemic arrest for open heart surgery could be enhanced considerably when coronary dilatation was assured.

• Journal of Chest Surgery
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• v.29 no.11
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• pp.1191-1196
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• 1996

Recently, if there is pulmonary hypertension in ventricular septal defect, early operation without pulmonary artery banding is recommended even though patient is under 1 year in age or has low body weight. We also had been performing operations under the above mentioned policy. From October 1986 to December 1995, eighty eight cases of ventricular septal defect under 10Kg in body weight were operated upon by open cardiac surgery. Mortality was compared by age, body weight and degree of pulmonary vascular hypertension. Total mortality was 10cases(11.4%); under 6months, the mortality was 5 in 14 cases(35.8%), from 6 months to 1year, 4 in 43 cases(9.3%) and over 1 year, one in 31 cases(3.2%), while there was no significant difference in mortality compared by degree of pulmonary vascular hypertension. And mortality under 6months in age was so high regardless of severity of pulmonary hypertension. After this exprience, too early operation,. especially under 6 months, should be considered very prudently, unless there were life threatning heart failure, impending irreversible pulmonary vascular bed change or failure to thrive.

• Clean Technology
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• v.24 no.4
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• pp.332-338
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• 2018

Currently graphite is used as an anode active material for lithium ion battery. However, since the maximum theoretical capacity of graphite is limited to $372mA\;h\;g^{-1}$, a new anode active material is required for the development of next generation high capacity and high energy density lithium ion battery. The maximum theoretical capacity of Si is $4200mA\;h\;g^{-1}$, which is about 10 times higher than the maximum theoretical capacity of graphite. However, since the volume expansion rate is almost 400%, the irreversible capacity increases as the cycle progresses and the discharge capacity relative to the charge is remarkably reduced. In order to solve these problems, it is possible to control the particle size of the Si anode active material to reduce the mechanical stress and the volume change of the reaction phase, thereby improving the cycle characteristics. Therefore, in order to minimize the decrease of the charge / discharge capacity according to the volume expansion rate of the Si particles, the improvement of the cycle characteristics was carried out by pulverizing Si by a dry method with excellent processing time and cost. In this paper, Si is controlled to nano size using vibrating mill and the physicochemical and electrochemical characteristics of the material are measured according to experimental variables.