• Korean Journal of Hazardous Materials
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• v.2 no.1
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• pp.1-5
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• 2014

Acidic chemicals like sulfuric acid, nitric acid and hydrogen chloride take up 37% of the total chemical accidents which took place for the past 10 years. When an acidic chemical leak happens, fume is generated, diffusing into the air, which might cause serious damage to health of local residents and the environment. However, we have only little reference data for production and using of acidic chemicals. In this study, we investigated characteristics of production and using for acidic chemicals with high accident frequency. As a results, domestic chemical accidents were categorized according to chemical types and production, using, and handling characteristics of acidic chemicals were identified. Sulfuric acid was handled in the largest amount, followed in the order of hydrogen chloride, nitric acid, acrylic acid, and hydrogen fluoride. Sulfuric acid is used in the industry of manufacturing composite fertilizer and mainly used for manufacturing fertilizer. Hydrogen chloride is used in the industry of manufacturing basic chemicals for petrochemical family and mainly used for pH regulator. It is expected that this results could be used as preliminary data for making decisions on facilities required intensive management in order to prevent chemical accidents and prepare countermeasures against such accidents.

• Corrosion Science and Technology
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• v.21 no.4
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• pp.273-281
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• 2022

The effect of addition of Cu on the localized corrosion performance of aged duplex stainless steel in chloride media has yet to be explained in a consistent manner, and there is some controversy in the literature regarding the composition of stainless steel and the experimental conditions (pH, temperature, chloride concentration, etc.) used. In this work, the effect of the addition of Cu on the microstructure, hardness, and corrosion resistance of duplex stainless steel in an acidic chloride or high concentration sulfuric acid solutions was investigated for annealed and aged alloys. The Cu addition of annealed duplex stainless steel strengthened the alloy and reduced the ferrite contents of the alloy, and it also increased the polarization behavior in chloride or sulfuric solutions, except for the case of a high potential in acidic chloride solution. However, the Cu addition of aged duplex stainless steel reduced the formation of harmful phases such as sigma and kai and increased the polarization behavior in acidic chloride or sulfuric solutions up to 0.8 wt% of the Cu content, after which it slightly decreased at 0.8 wt% Cu or more.

• Journal of Microbiology and Biotechnology
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• v.33 no.7
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• pp.857-863
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• 2023

Pathogenic bacteria that colonize the human intestinal tract have evolved strategies to overcome acidic conditions when they pass through the gastrointestinal tract. Amino acid-mediated acid resistance systems are effective survival strategies in a stomach that is full of amino acid substrate. The amino acid antiporter, amino acid decarboxylase, and ClC chloride antiporter are all engaged in these systems, and each one plays a role in protecting against or adapting to the acidic environment. The ClC chloride antiporter, a member of the ClC channel family, eliminates negatively charged intracellular chloride ions to avoid inner membrane hyperpolarization as an electrical shunt of the acid resistance system. In this review, we will discuss the structure and function of the prokaryotic ClC chloride antiporter of amino acid-mediated acid resistance system.

• Korean Chemical Engineering Research
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• v.48 no.5
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• pp.643-648
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• 2010

Production of biodiesel from soybean oil catalyzed by Lewis acidic ionic liquids(ILs) containing metal chloride salts was investigated in this study. Metal chloride salts, such as $SnCl_2$, $ZnCl_2$, $AlCl_3$, $FeCl_3$ and CuCl, were screened for oil transesterification in the range of 363-423 K. Among these metal chlorides, tin chloride showed particularly high catalytic property for the oil transesterification. Similarly, among these Lewis acidic ionic liquid catalysts, $[Me_3NC_2H_4OH]Cl-2SnCl_2$ resulted in a high fatty acid methyl esters(FAMEs) content of 91.1% under the following reaction conditions: 403 K, 14 h, and a molar ratio of 1:12:0.9 (oil:methanol:catalyst). Unlike the pure tin chloride catalysts, Lewis acidic ILs containing tin chloride $[Me_3NC_2H_4OH]Cl-2SnCl_2$ catalyst could be recycled up to five times without any significant loss of activity by separating from the FAMEs with simple decantation. The Lewis acidity and high moisture-stability of this catalyst appeared to be responsible for the excellent catalytic performance. The effects of reaction time and the molar ratio of methanol/catalyst to oil on the FAMEs production were also studied in this work.

• Journal of the Korean Electrochemical Society
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• v.9 no.2
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• pp.70-76
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• 2006

Micro-droplet cell with free droplet as a micro-electrochemical technique has been limited to apply to electrochemical systems with high wetting properties such as an acidic solution and low grade stainless steels(Type 316L). By loading negative pressure to a droplet, control of droplet size, and use of hydrophobic gasket, the cell is modified to be allowed to use for electrochemical systems with high wetting properties. For giving the reliability of new cell, studies on local corrosion were conducted for three different systems-an acidic chloride solution and high chromium ferritic stainless steel, the other acidic chloride solution and type 316, and a neutral chloride solution and type 316. stainless steel. Firstly, the modified micro-droplet cell allows the anodic polarization curves in an acidic chloride solution to show the fact that the local corrosion of high chromium stainless steel near the $\alpha/\sigma$ interface is due to the Cr depleted zone. Secondly, the local anodic polarization test of type 316 L in the other acidic chloride solution can be successfully conducted in the cell. Furthermore, the local polarization curves help elucidating the corrosion of type 316 with $\delta-ferrite$ phase. Finally, the polarization curves of type 316 L in a neutral chloride solution indicates that the factor affecting the pitting corrosion resistance was inclusions rather than $\delta-ferrite$.

• Corrosion Science and Technology
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• v.22 no.3
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• pp.137-152
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• 2023

Polarization behavior and corrosion inhibition of copper in acidic chloride solutions containing benzotriazole were studied. Pourbaix diagrams constructed for copper in NaCl solutions with different BTAH concentrations were used to understand the polarization behavior. Open circuit potential (OCP) depended not only on chloride concentration, but also on whether a CuBTA layer was formed on the copper surface. Only when the (pH, OCP) was located well in the CuBTA region of the Pourbaix diagram, a stable corrosion inhibiting CuBTA layer was formed, which was confirmed by X-ray Photoelectron Spectroscopy (XPS) and a long-term corrosion test. The OCP for the CuBTA layer decreased logarithmically with increasing [Cl^-] activity in the solution. A minimum BTAH concentration required to form a CuBTA layer for a given NaCl concentration and pH were determined from the Pourbaix diagram. It was found that 320 ppm BTAH solution could be used to form a corrosion-inhibiting CuBTA layer inside the corrosion pit in the sprinkler copper tube, successfully reducing water leakage rate of copper tubes. These experimental results could be used to estimate water chemistry inside a corrosion pit.

• IMMUNE NETWORK
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• v.23 no.3
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• pp.23.1-23.17
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• 2023

Inflammation is a series of host defense processes in response to microbial infection and tissue injury. Inflammatory processes frequently cause extracellular acidification in the inflamed region through increased glycolysis and lactate secretion. Therefore, the immune cells infiltrating the inflamed region encounter an acidic microenvironment. Extracellular acidosis can modulate the innate immune response of macrophages; however, its role for inflammasome signaling still remains elusive. In the present study, we demonstrated that macrophages exposed to an acidic microenvironment exhibited enhanced caspase-1 processing and IL-1β secretion compared with those under physiological pH. Moreover, exposure to an acidic pH increased the ability of macrophages to assemble the NLR family pyrin domain containing 3 (NLRP3) inflammasome in response to an NLRP3 agonist. This acidosis-mediated augmentation of NLRP3 inflammasome activation occurred in bone marrow-derived macrophages but not in bone marrow-derived neutrophils. Notably, exposure to an acidic environment caused a reduction in the intracellular pH of macrophages but not neutrophils. Concordantly, macrophages, but not neutrophils, exhibited NLRP3 agonist-mediated translocation of chloride intracellular channel protein 1 (CLIC1) into their plasma membranes under an acidic microenvironment. Collectively, our results demonstrate that extracellular acidosis during inflammation can increase the sensitivity of NLRP3 inflammasome formation and activation in a CLIC1-dependent manner. Thus, CLIC1 may be a potential therapeutic target for NLRP3 inflammasome-mediated pathological conditions.

• Nuclear Engineering and Technology
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• v.32 no.6
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• pp.531-536
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• 2000

The extraction of precious metals from aqueous solutions is performed by using a photoredox reaction with a Q-switched Nd:YAG laser. The metallic silver was efficiently precipitated and extracted from the silver nitrate solution by laser photolysis. An optimum reaction condition for silver extraction was determined by adjusting various experimental factors such as type of reducing agent, type of acids and reaction time. The composition of the reaction product was analyzed and it was identified as metallic silver, not other molecular types. The photoreaction of chromium(III) chloride in an acidic aqueous solution was also investigated. The 355 nm laser light was better suited for the reaction of silver nitrate as well as chromium(III) chloride in an acidic solution compared to the 532 nm light.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1436-1440
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• 2007

Beryllium copper has been known to be an important material for the various fields of industry because it can be used for mechanical and electrical/electronic components that are subjected to elevated temperatures (up to $400^{\circ}C$ for short times). Blade type tip for probing the cells of liquid crystal display(LCD) was fabricated using beryllium copper foil. The dry film resist was employed as a mask for patterning of the blade type tip. The beryllium copper foil was etched using hydrochloric acidic iron-chloride solution. The concentration, temperature, and composition ratio of hydrochloric acidic iron-chloride solution affect the etching characteristics of beryllium copper foil. Nickel with the thickness of $3{\mu}m$ was electroplated on the patterned copper beryllium foil for enhancing its hardness, followed by electroplating gold for increasing its electrical conductivity. Finally, the dry film resist on the bridge was removed and half of the nickel was etched to complete the blade type tip.

• Bulletin of the Korean Chemical Society
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• v.10 no.2
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• pp.208-210
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• 1989