• 한국표면공학회지
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• 제24권2호
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• pp.103-113
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• 1991

Electroless Ni-Cu-P alloy plating of Al base hard disk was performed to investigate some properties according to the change of composition. It was found that the composition of Ni and Cu in deposits changed linearly with increasing the mole ratio of NiSO4.6H2O/CuSO4.5H2O. The increase in hardness by heat - treatment was confirmed to be associated with small size grained crystallization of the amorphous deposits. Acid resistance of all deposits layer. which had been heated up to 30$0^{\circ}C$, was found to be exellent when immersed in 1N-H2SO4 solution, and it showed more superior acid resistance with decreasing Cu content and with increasing P. The resistivity of the deposits heat treated became smaller at temperature more than 50$0^{\circ}C$, and it became largerly with increasing P content. Cu 44.1wt% alloy(C bath) showed the most superior non-magnetically stable characteristics after heat treatment. It was superiorly with higher temperature and with decreasing P content.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 총회 및 춘계학술발표회
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• pp.168-171
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• 2001

Organobentonite modified with hexadecyltrimethylammonium (HDTMA) was used to quantify an adsorption of heavy metals. Based on preliminary experiments, optimal soil/solution ratio, a range of pH, and electrolyte were selected. Adsorption experiments of cadmium and lead were conducted to quantify an adsorption selectivity to bentonite and organobentonite. Adsorption of cadmium and lead to bentonite was increased with increasing a soil/solution ratio. Adsorption of cadmium and lead to bentonite was increased with increasing a soil/solution ratio. Adsorptions of heavy metal to organobentonite were slightly reduced relative to bentonite. This study used the principle of hard-soft-acid-base (HBAB) to interpretate an adsorption mechanism. Because of competition between cadmium and lead. adsorption of cadmium and lead was reduced in mixture of heavy metals. Adsorption selectivity.

• 한국염색가공학회지
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• 제23권2호
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• pp.107-117
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• 2011

Polyurethane (PU) was synthesized by one-shot process and the PU nanofiber was prepared by electrospinning. In this study, electrospun PU multi-membranes were prepared with various coating thickness ratio of base resin to top resin, where the base resin contains melamine curing agent and acid catalyst and the top resin contains water-repellent agent of fluoro-carbon compounds. The PU nanofiber multi-membranes were analyzed by field-emission scanning electron microscopy, differential scanning calorimeter, breathability, tensile strenth, air permeability and water resistance. The results showed that the PU multi-membrane provided excellent waterproof and moisture permeability.

• Journal of the Korean Wood Science and Technology
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• 제16권4호
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• pp.70-78
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• 1988

To separate and utilize the main components of hardwood (Quercus mongolica) by organosov pulping (ester pulping), chips were cooked at various conditions such as; the solvent ratio (acetic acid: ethylacetate: water, 50:25:25; 33:33:34; 25:50:25), maximum temperature (165, 170, $175^{\circ}C$), and cooking times (2, 2.5, 3 hr). The pulps were bleached by the sequences of CEDED, C/DEDED, PEDED. Lignin, sugars, and acetic acid were separated from black liquor and washing liquors. 1. The selective delignification at optimal pulp yield (43-45%) was obtained by cooking at acetic acid: ethylace tate: water ratio of 33:34:34 for 3 hr at $170^{\circ}C$. But in this case, kappa no. of the pulp was not reduced under 60 points. 2. Kappa no. of the pulp could be dropped by an acetone wash to remove reprecipitated lignin a t cooked pulp. 3. The unbleached pulps had a brightness of 45-50%, whereas the bleached pulps gave at 88-93% brightness. Tensile, burst, and tear strengths of the bleached pulps were lower than those of kraft pulp, especially in tear strength. The pulps which were bleached with CEDED sequence were higher in strengths than another bleaching sequences. 4. Lignin of 90-95%(lignin base on wood)was separated from black liquor and washing liquors, while the purified sugars and recovery of acetic acid were a low. An organic phase composed of acetic acid, ethylacetate, and water was separated to a two-phase system by proper adjustment of the solvent ratios.

• 공업화학
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• 제30권3호
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• pp.358-364
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• 2019

반사 방지(anti-reflective; AR) 코팅막의 광학 특성 및 내오염성을 향상하기 위하여 tetraethylorthosilicate (TEOS)/염기 및 methyltrimethoxysilane (MTMS)/산 혼성 용액의 혼합비를 변화시키며 다양한 AR 코팅막을 제조하였다. 제조된 AR 코팅막은 UV-Vis, 접촉각 측정기, AFM, FT-IR 및 연필 경도 시험을 통해 특성을 분석하였다. MTMS/산 용액의 함량이 10 wt%인 혼성 용액으로 제조한 AR 코팅막에서 유리 기판은 매우 우수한 광학 특성(97.2%의 투과율), 우수한 내오염성($121^{\circ}$의 물 접촉각 및 $90^{\circ}$의 $CH_2I_2$ 접촉각), 중간 정도의 기계적 강도(4 H의 연필 경도)를 나타내었다. 특히 우수한 내오염성은 기판의 표면 위에서 혼성 용액 내 소량의 MTMS/산 용액으로부터 유래된 메틸기($-CH_3$)의 고른 분산에 기인한 것으로 고려되었다. 연필 경도 시험 결과로부터, AR 코팅막의 기계적 강도는 MTMS/산 용액의 함량이 증가할수록 향상되는 것으로 나타났다.

• 약학회지
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• 제45권1호
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• pp.46-54
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• 2001

Protein carboxyl Ο-methylation is a kind of enzymatic reaction producing carboxyl methylester catalyzed by protein carboxyl Ο-methyltransferases at the carboxyl group of amino acid residues in polypeptide. Since the finding of carboxyl methylesterl many studies have been focused on the under-standing of biological functions in eukaryotes but still not clear except for roles in Ras attachment to membrane and protein repair. In this study, we investigated the protein carboxyl methylation in porcine liver and testis in respect of identification and characterization of carboxyl methylesters and natural proteinous substrates using pH stability of the esters and electrophoresis under acidic and basic conditions. We detected several kinds of methyl esters, 3 kinds each in cytosolic fractions from liver and testis. Under the treatment of strong acid and base, the ratio between base-stable substrates and unstable ones in liver (4 : 6) was different from the ratio obtained in testis (6 : 4). The methyl accepting capacities were affected by enzymatic proteolysis between the range of 55 to 65% in liver and of 35 to 45% in testis. Separation of the methylated proteins by acidic electrophoresis in the presence of urea and SDS revealed distinctively natural substrates of 26, 33 and 80 kD in the cytosol from liver and of 14, 25, 32 and 86 kD from testis. Most of the labelling, however were lost following electrophoresis under moderate alkaline condition, except for molecules of newly detected 7 and 17 kD in livers and 15, 29, 40 and 80 kD in testis. From these results, it was proposed that protein carboxyl Ο-methylation in each organs may be catalyzed by different classes of protein carboxyl Ο-methyltransferases. In addition, it is suggested that the protein carboxyl methylation in liver and testis may have different patterns in respect of natural substrates.

• 대한화학회지
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• 제5권1호
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• pp.33-37
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• 1961

We have shown that carboxy-peptidase destroys the biological activity of angiotensin octa-and deca-peptides. Since Proline occurs as the seventh amino acid from the amino end of the chain and since carboxypeptidase does not cleave proline from a peptid chain, it is evident that the heptapeptid H.asp-arg-val-tyr-ileu-his-pro.OH is formed by this hydrolysis. This peptide must then be biologically inactive. In order to determine whether the phenyl group of the C-terminal amino acid was the necessary requirement for biological activity of the octapeptide, $ala^8$ angiotensin octapeptide(amino acids of peptides numbered from amino end) was synthesized. For this synthesis the four dipeptides were prepared: carbobenzoxy-L-prolyl-L-alanine-P-nitrobenzyl-ester, m.p. $134-135^{\circ}C,$ carbobenzoxy-L-isoleucyl-imidazole benzyl-L-histidine methyl ester, m.p. $114-116^{\circ}C,$ carbobenzoxy-L-valyl-L-tyrosine hydrazide and carbobenzoxy B-benzyl-L-aspartyl-nitro-L-arginine. The first three dipeptides were obtained as crystalline compounds. Imidazole-benzyl-L-histidine was used in the hope that it would block the histidine imidazole against side reactions in steps subsequent to the formation of the C-terminal tetrapeptide. Also, it was through that the imidazole benzylated peptides would be easier to crystallize. This, however, was not the case. The tetrapeptide, carbobenzoxy-L-isoleucyl-L-im, benzyl-histidyl, L-prolyl-L-alanine-nitrobenzyl ester was not obtained in a crystalline form. Neither could the mono-or dihydrobromide of the tetrapeptide free base be induced to crystallize. Carbobenzoxy-L-valyl-L-tyrosine azide was condensed with the tetrapeptide free base to yield the protected hexapeptide; carbobenzoxy-L-valyl-L-tyrosyl-L-isoleucyl-L-im, benzyl, histidyl-L-Prolyl-L-alanine-nitrobenzyl ester. Upon removal of the carbobenzoxy group with hydrogen bromide in acetic acid an amorphous free base hexapeptide ester was obtained. This compound gave the correct C, H, N analysis and contained the six amino acids in the correct ratio. The octapeptide was obtained by condensing this hexapeptide with carbobenzoxy-B-benzyl-L-aspartyl-nitro, L-arginine using the mixed anhydride method of condensation. This amorphous product was proven to be homogenous by chromatography in two solvent systems and upon hydrolysis yielded the eight amino acids in correct ratio. The five protecting groups were removed from the octapeptide by hydrogenolysis over palladium black catalyst. Biological assay of the free peptide indicated that it possessed less than 0.1 per cent of both pressor and oxytocic activity of the phenylalanine8 angiotensin. This suggests that the phenyl group is a point of attachment between angiotensin and its biological receptor site.

• 한국농공학회지
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• 제11권1호
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• pp.1604-1615
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• 1969

본(本) 실험(實驗)은 cement mortar를 고산용액에 침지(浸漬)시켜 산(酸)의 작용(作用)에 의(依)한 모르타르의 부식(腐蝕)이 모르타르의 물리적성질(物理的性質)에 미치는 영향(影響)을 구명(究明)하여 보다 내산성(耐酸性) 모르타르 또는 콘크리트의 배합설계(配合設計)에 기초자료(基礎資料)를 제시(提示)하고저 시도(試圖)하였던 바 그 결과(結果)를 요약(要約)하면 다음과 같다. 가. 공시체(供試體)는 5cm 입방체(立方體)의 모르타르로서 그 배합비(配合比)(중량(重量))는 1:1, 1:3, 1:5, 1:7, 1:10의 5종(種)을 제작(製作) 사용(使用)하였다. 나. 물리시험(物理試驗)에서는 재령(材令) 7일(日), 28일(日), 3개월(個月), 6개월(個月)의 압축강도시험(壓縮强度試驗)과 5시간(時間) 자비(煮沸)의 흡수율시험(吸水率試驗)을 하였다. 다. 산성시험(酸性試驗)에서는 0.1N-Hcl 용액(溶液)을 사용(使用)하고 7일간격(日間隔)으로 감량(減量)을 7주간(週間) 계속측정(繼續測定)하였다. 라. 물리적(物理的) 제성질(諸性質)인 배합비(配合比), w/c/비(比), 흡수율(吸水率), 압축강도(壓縮强度) 및 밀도간(密度間)의 상호관계(相互關係)는 다음식(式)으로 표시(表示)되었다. 1. 배합비(配合比)와 흡수율(吸水率)과의 관계(關係) Y=1.036X+13.53 여기서 Y : 흡수율(吸水率)(%), X: 배합비(配合比) 2. 배합비(配合比)와 w/c 비(比)와의 관계(關係) Y=0.214+0.204X 여기서 Y:w/c 비(比), X: 배합비(配合比) 3. w/c 비(比)와 흡수율(吸水率)과의 관계(關係) Y=5.01X+12.53 여기서 Y: 흡수율(吸水率)(%) X: w/c비(比) 4. 밀도(密度)와 흡수율(吸水率)과의 관계(關係) Y=50.6-0.0176X 여기서 Y: 흡수율(吸水率)(%) X: 밀도(密度)($kg/m^3$) 5. 밀도(密度)와 w/c 비(比)와의 관계(關係) Y=5.46-0.0024X 여기서 Y: w/c비(比) X: 밀도(密度)($kg/m^3$) 마. 7주간(週間) 0.1N-HCl 용액(溶液)에 침지후(浸漬後) 감량(減量)의 범위(範圍)는 배합비(配合比) 1:1에서 20.4%(最小), 1:10에서 9%(最大)이였다. 바. 감량(減量)과 물리적(物理的) 제성질(諸性質)과의 관계(關係)는 다음식(式)으로 표시(表示)되었다. 1. 감량(減量)과 배합비(配合比)와의 관계(關係) Y=8.59X+8.63 여기서 Y: 감량(減量)(%) X: 배합비(配合比)

• 약학회지
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• 제44권6호
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• pp.545-551
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• 2000

Magnesium trisilicate was prepared by reacting Magnesium sulfate solution with Sodium silicate solution in this study. The optimum synthesis conditions base on the yield of the product were established by applying Box-Wilson experimental design. It was found that the optimum synthesis conditions of Magnesium trisilicate were as follows; Reacting temperature : $57{\sim}90^{\circ}C$, Concentration of reactant solution : $19.1{\sim}20.0%$, Molar concentration ratio of two reactants : [Sod.silicate]/[Mg.sulfate] : $1.47{\sim}1.80$, Temperature of washing water : $45{\sim}48^{\circ}C$, Drying temperature : $65{\sim}82^{\circ}C$. The antacidic capacity of the five Magnesium trisilicate samples which shows the maximum antacidic efficacy was tested by pharmacopeia acid consuming capacity test. The five Magnesium trisilicate samples were identified by chemical analysis.

• 한국대기환경학회지
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• 제4권1호
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• pp.33-44
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• 1988

For the purpose of examining the effects of simulated acid rain on the chemical properties of the experimental soil in Pinus densiflora seedlings and Forsythia koreana rooted cuttings, the experimental design of randomized block arrangement with three replications was implemented in the experimental field of Yesan National Agricultural Junior College. One-year-old Pinus densiflora seedlings and Forsythia koreana cuttings were planted in the pots filled the mixed soils (nursery soil: forest soil of siliceous sandy loam = 1 : V/V)in the early spring of 1985. The regime of artificil acid rain, in terms of spray frequency per monthly and spray amount at single treatment per plot, was simulated on the basis of climatological data averaged from 30 years records. Simulated acid rain (pH 2.0, pH4.0, and pH 5.5 as control) containing sulfuric and nitric acid in the ratio of 3:2 (chemical equivalant basis) diluted ground water, were treated on the experimental plants under condition of cutting off the natural precipitation with vinyl tunnel, during the growing season (May 1 to August 31) in 1985. THe results obtained in this study were as follows; 1. Soil acidity was dropped, and exchangeable aluminum contents in the soil was dramatically increased in both species, with decreasing pH levels of acid rain. 2. Exchangeable potassium, clacium, magnesium contents, and base saturation degree of the soil were highly drcreased in two species as the pH levels of acid rain decreased. 3. In two species, sulfate concentrations in the soil were decreased of pH 4.0 treatment, and remarkably increased at pH 2.0 treatment of acid rain in comparison with control. 4. Total nitrogen and available phosphate contents of the soil were not affected by acid rain treatment in the both species, and Fe contents at pH 2.0 treatment were highest among three acid rain treatments.