• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1029-1035
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• 2014

The protolytic dissociation process of hydrochloric acid (HCl) and hydrofluoric acid (HF) is studied using the B3LYP and MP2 methods with the 6-311+G(d,p) basis set in the gas phase and in aqueous solution. To study the phenomena in detail, discrete and discrete/continuum models were applied by placing water molecules in various positions around the acid. The dissociation process was studied using the thermodynamic cycle involving the structures optimized both in the gas phase and in aqueous solution and was analyzed with two key energy factors, relaxation free energy (${\Delta}G_{Rex(g)}$) and solvation free energy (${\Delta}G_s$). Based on the results, we could understand the dissociation mechanism and wish to propose the best way to study acid dissociation process using the CPCM methodology in aqueous solution.

• 자원리싸이클링
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• 제27권5호
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• pp.69-76
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• 2018

추출제로 Cyanex 572를 사용하여 염산용액에서 [Sm]과 [Pr, Nd]그룹을 분리하기 위해 Xu Guangxian이 제시한 이론에 의하여 최적 향류 추출 공정 변수를 계산하고자 하였다. 기초실험으로부터, [Sm]/[Pr, Nd]의 두 그룹 최적 분리계수는 추출공정의 경우 pH 1.75에서 14.59, 세정공정에서는 0.01M HCl에서 14.61 이었다. [Sm]과 [Pr, Nd] 그룹분리에 필요한 공정 변수에 대해 계산을 하였다. 계산 결과 두 그룹의 희토류 분리에 필요한 총 추출 및 세정 단수는 11단이었으며, 최적추출비를 유지시키기 위해 필요한 원료용액, 추출용액 및 세정용액의 유량비는 0.1 M HCl을 사용하였을 경우 6.25 : 1.74 : 5.80 이었다.

• Journal of Periodontal and Implant Science
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• 제27권1호
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• pp.79-90
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• 1997

The purpose of this study was to evaluate the substantivity of experimentally developed gel type tetracycline HCl and a mixture of tetracycline-citric acid gel, and compare to those of solution type tetracycline HCl. 11 extracted anterior teeth were subjected to this study. After scaling and root planing teeth were randomly divided into 3 treatments groups : group 1; 3 teeth were irrigated with tetracycline HCl(50mg/ml) solution , group 2; tetracycline gel (5%) was inserted in the periodontal pockets of 3 teeth, group 3; a mixture of tetracycline and citric acid gel was inserted in the pockets of 3 teeth. And 2 teeth treated in 0.9 % sterile saline served as controls. After 5-minute exposure, each tooth immediately extracted and incubated at room temperature for 22 days in tris-buffered saline as a desorption media. The total volume of TBS was removed and replaced with fresh TBS, at 24-h intervals. Removed desorption media transferred to a sterile vial and stored at -70 oC. This procedure was repeated every 24 h throughout the 22-day desorption period. Using Porphyromonas gingivalis as an indicator organism, a microtiter assay was used to evaluate antimicrobial activity desorbed from the teeth. 1. 50mg/ml tetracycline HCl solution exhibited the longest antimicrobial activity. Compared to saline treated group, it showed significant difference on the day 1 and day 2 desorption period. 2. The ODs of 5% tetracycline gel and a mixture of tetracycline-citric acid gel were significantly different during the first 24 hour only. 3. There was no statistically significant difference after the day 3 between the groups.(p<0.05). Despite our expectation a mixture of tetracycline-citric acid gel did not show longer antimicrobial activities than those of tetracycline gel, and the solution type exhibited the longest activities. Because the gel type agents may stay in the subgingival environment longer than the solution, if the teeth were not extracted immediately after the delivery of the agent, the result could be different. hus this result suggests the possibilities of practical use of these kind of gel type agents.

• 미생물학회지
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• 제9권3호
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• pp.103-120
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• 1971

We have been studied on brewing sweet starch. We obtained the results as follows ; 1) 5 strains, T-T-2, T-T-4, T-K-2, T-T-18, T-T-1, were the most available in view of fermentative power by capacity of $CO_2$. 2) 5 strains, T-T-4, T-T-2, T-T-1, T-T-3, T-K-2, produced capacity of alcohol more than 5.78%. 3) 6 strains, T-T-2, T-K-2, T-T-4, T-S-2, T-I-3, T-I-1, are available not only taste and flavour, but productive power of alcohol in sweet potato starch. 4) The form of 6 strains are long oval and round and most of them are similar to the other yeast in size. 5) In giant colony the color was cream color and cream buff, and T-K-2 was formed by $15{\times}12mm$ on diameter and by 3.5mm on high. 6) Optimum temperature of most of all strains is 25~ $300^{\circ}C$but T-K-4 is 28-30.deg.C. 7) Optimum pH is 3.4-4.6. 8) T-S-2 was died off at 65.deg.C, the other strains died $60^{\circ}C$. 9( Making Bun-kok with non-heated wheat bran .alpha.-amylase was more increased by 4.5-13.5 mg of glucose in reaction solution and .betha.-amylase more 1.6-3.4ml of N/10-$KMnO_4$ Solution than Bun-kok with heated wheat bran. 10) It seems that mycellium grows better than original in substance containing 0.4 ~ 1.2% of HCl. 11) Making Bun-kok to add 0.8% HCl, .alpha.-amylase was increased 9.93-20.7mg of glucose and .betha.-amylase ws increased 2.6~4.3ml of N/10-$KMnO_4$ solution to reaction solution. 12) 1.2%-HCl, or higher concentration, acts as inhibitor, in the meanwhile the concentration between 0.4~0.8% of HCl acts as activator. 13) We must make Bun-kok for 42 hours, at 28~$30^{\circ}C$) After we made Bun-kok using S-O-II and R-J-I one by one, Bun-kok which mix each other in equal quantity is increased more than original on enzyme acrivity. 15) Oxidation is the best way of refining sweet potato starch in N/10-phosphate buffer solution (pH 7.5). 16) When we prepared sweet potato starch, first pH was 3.0.

• 한국구조물진단유지관리공학회 논문집
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• 제26권2호
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• pp.1-8
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• 2022

철근 콘크리트 구조물 수명 저하의 주요한 원인은 콘크리트 내부 철근의 부식이다. 이때 사전 부식된 구조물 내부 철근은 다른 철근에 비해 더 쉽게 부식되며, 특히 구조물이 습기 또는 염화 환경에 노출된 경우 부식의 진행속도가 매우 빠른 것으로 알려져 있다. 본 연구에서는 시멘트 복합재 내부의 사전 부식 철근에 대한 서로 다른 양생 용액이 부식에 미치는 영향을 탐구하였다. 철근의 사전 부식을 촉진하기 위해 HCl(3%)용액과 CaCl2(10%)용액을 활용하였으며, 대조군(RE)을 포함한 3종의 사전 부식 철근 모르타르 실린더를 타설하였다. 철근 모르타르 실린더는 CaCl2(3%) 용액과 수돗물에서 각각 120일 동안 양생하며 실험을 진행하였다. 사전 부식 철근의 모르타르 내부 부식 거동에 대한 양생 용액의 영향을 평가하기 위해 전기화학적 분극저항(Electrochemical Polarization)과 반전지 전위 측정법(Half-cell potential)을 활용하였으며, 전자주사현미경(SEM)과 X선 회절 분석(X-ray Diffraction Analysis)을 통해 부식된 철근의 표면 상태와 성분을 분석하였다. 실험 결과 두 종류의 양생 용액에서 사전 부식된 철근의 부식률은 사전 부식되지 않은 시료의 부식률보다 높은 것으로 나타났으며, CaCl2 용액 양생 120일의 RE, CaCl2, HCl 사전 부식 시편의 최종 부식 속도가 수돗물에 양생한 경우보다 각각 8.14, 4.48, 13.81배로 높았다.

• 한국미생물·생명공학회지
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• 제50권2호
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• pp.211-217
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• 2022

차아염소산나트륨(NaClO)은 병원 및 식품산업 분야에서 널리 사용되는 소독제로 세균, 곰팡이, 바이러스에 대해서도 항균 활성이 있다. 차아염소산나트륨의 항균 활성은 용액의 pH에 의해 조절되는 안정적인 HClO 농도의 유지에 있다. 차아염소산(HClO)은 화학적으로 중성이므로 세균의 막에 쉽게 침투할 수 있으며 차아염소산나트륨의 항균 활성은 차아염소산염 이온(ClO^-)보다는 용액 내 HClO 농도에 의존하리라 사료된다. 본 연구에서 pH 조절에 따른 차아염소산나트륨의 항균 활성을 time kill test와 차아염소산나트륨 처리 전후의 활성산소종(ROS) 및 ATP 농도 변화로 조사하였다. 또한 전계방출형 주사 전자 현미경(FE-SEM)을 통하여 세포벽의 파괴정도를 확인하였다. pH 5 조건에서 5 ppm 차아염소산나트륨은 Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) 균에 대하여 99.9%의 항균 활성을 나타내었고, ROS 생성량은 pH 7 조건보다 48% 증가하였다. 또한, pH 5 조건의 차아염소산나트륨에 노출된 E. coli와 S. aureus의 ATP 농도가 각각 94%와 91% 감소하였다. FE-SEM 결과, pH 5 조건에 노출된 균의 세포벽이 파괴된 것을 확인하였다. 본 연구결과를 종합해보면, pH를 조절하는 것 만으로 5 ppm 농도의 차아염소산나트륨의 항균 활성을 향상시킬 수 있음을 시사한다.

• 대한임상검사과학회지
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• 제48권4호
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• pp.371-377
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• 2016

탈회방법은 골수조직의 병리학적 진단을 위해서 항상 시행되는 과정이다. HCl 탈회용액과 같이 주로 사용하고 있는 산성용액은 탈회과정 동안에 조직내의 항원성에 손상을 입힌다. 특히, 골수조직 내의 RNA나 DNA에 심하게 손상을 준다. 따라서 조직의 항원성을 보존하기 위한 표준화된 탈회방법이 필요하다. 본 연구는 일반적으로 가장 많이 사용되는 HCl 기반의 상품화된 탈회용액과 직접 제조한 EDTA 탈회용액이 골수조직의 탈회과정에 어떤 영향을 미치는지 분석하였다. 환자로부터 채취된 73예의 골수생검조직을 HCl 탈회와 EDTA 탈회의 두 그룹으로 나누어 탈회과정을 진행하였다. 골수생검조직의 탈회과정 후 결과의 차이는 hematoxylin & eosin 염색과 reticulum 염색, Ki-67, CD20, CD138의 항체를 이용한 면역조직화학염색, DNA 추출 및 분석, in situ hybridization, IGH gene rearrangement 와 같은 분자병리검사를 시행하여 분석하였다. 일반적인 염색과 특수염색에서는 두 탈회용액간의 차이는 없었다. 또한 세포증식 표지자와 같은 세포막 혹은 세포질에서 발현되는 항체는 탈회용액간의 차이 없이 잘 염색되었다. 반면 HCl 탈회 용액에 처리한 후 핵 내 단백질인 Ki-67의 염색상은 현저히 불량한 것으로 관찰되었다. HCl 탈회용액과 비교하여 EDTA 탈회용액에서의 골수생검조직 내의 DNA와 RNA가 잘 보존되었음을 다양한 분자병리검사를 통해 확인할 수 있었다. 특히 HCl 탈회용액에 처리한 28예와 EDTA 탈회용액에 처리한 12예의 DNA의 순도와 농도을 비교한 결과 통계학적으로 유의한 수준으로 차이가 있음을 확인하였다. 이로써 EDTA 탈회용액이 조직 내의 항원성을 잘 유지시키며, 면역조직화학염색과 분자병리검사에 적합한 방법임을 확인 할 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제31권7호
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• pp.1945-1950
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• 2010

Solvent extraction experiments of Pt(IV), Pd(II) and Rh(III) by Alamine336 were performed from the mixed chloride solutions. In the HCl concentration range from 1 to 5 M, most of Pt and Pd were extracted from the mixed solutions. However, the extraction percentage of Rh was much smaller than that of Pt and Pd. Lower concentration of Alamine336 in strong HCl solution led to higher separation factor of Rh from Pt and Pd. Adding $SnCl_2$ to the mixed solutions increased the extraction percentage of Rh, while the extraction percentage of Pt and Pd was little affected. Our results showed that selective separation of Rh or coextraction of the three platinum group metals from the mixed solution would be possible by adjusting the extraction conditions.

• 한국세라믹학회지
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• 제32권6호
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• pp.735-747
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• 1995

The synthesis of clay mineral through the hydrothermal reaction of the anorthite, which is distributed in San Chung-District of Korea and called as the ground rock for halloysite-kaolin, has been investigated. It was observed that this anorthite sample was easily converted into clay mineral with 0.5 wt% HCl solution at a temperature below 20$0^{\circ}C$ under a pressure about 15 atm. The conversion reaction was promoted by adding aluminum chloride under the condition concerned. Aluminum chloride was considered to supply the insufficient aluminum ion during the conversion reaction and to reprepare the acid solution-condition by adding the HCl-component as a by-product. According to the electron micrographs, it was confirmed that fine tubular or needle-shaped halloysite-kaolin minerals with the crystal length shorter than about 1.1${\mu}{\textrm}{m}$ could be obtained by the hydrothermal reaction for 5 days under those conditions.

• Bulletin of the Korean Chemical Society
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• 제30권7호
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• pp.1526-1530
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• 2009

Solvent extraction reaction of Zn(II) by Alamine336 from strong HCl solution up to 10 M was identified by analyzing the data reported in the literature. The equilibrium constant of this reaction was estimated by considering the complex formation between zinc and chloride ion. The necessary thermodynamic parameters, such as equilibrium constant for the formation of complexes and the interaction parameters, were evaluated from the thermodynamic data reported in the literature. The following solvent extraction reaction and the equilibrium constant was obtained by considering the activity coefficients of solutes present in the aqueous phase with Bromley equation. $Zn^{2+}\;2Cl^{-}\;+\;R_3NHCl_{org}\;=\;ZnCl_3R_3NH_{org},\;K_{ex}\;=\;6.33\;{\times}\;10^2$ There was a good agreement between measured and calculated distribution coefficients of Zn(II).