• 대한화학회지
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• 제57권6호
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• pp.703-711
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• 2013

In the present investigation, kinetic studies of oxidation of formic acid with and without catalyst and promoter in aqueous acid media were studied under the pseudo-first order conditions [formic acid]T ${\gg}[Cr(VI)]_T$ at room temperature. In the 1,10-phenanthroline (phen) promoted path, the cationic Cr(VI) phen complex is the main active oxidant species undergoes a nucleophilic attack by the substrate to form a ternary complex which subsequently experiences a redox decomposition through several steps leading to the products $CO_2$ and $H_2$ along with the Cr(III) phen complex. The anionic surfactant (i.e., sodium dodecyl sulfate, SDS) and neutral surfactant (i.e., Triton X-100, TX-100) act as catalyst and the reaction undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Whereas the cationic surfactant (i.e., N-cetyl pyridinium chloride, CPC) acts as an inhibitor restricts the reaction to aqueous phase. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. The neutral surfactant TX-100 has been observed as the suitable micellar catalyst for the phen promoted chromic acid oxidation of formic acid.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.789-792
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• 1999

Reinforced concrete structures covered creek for road vehicle located in urban areas have been experiencing corrosion of concrete and reinforcing steel caused by $H_2S$ gases generated by anaerobic bacterial. H2S gases react with oxygen and water to form sulfuric acid ($H_2SO_4$). This acid chemically attacks concrete, and sulfate ions penetrate into the concrete, causing rebar corrosion. In this work, to determine the conditions of RC culvert boxes which were constructed in the 1970s, various tests were conducted, including carbonation depth, compressive strength, half-cell potential measurements, and XRD analyses. Results indicated that the concrete deterioration was caused by sulfate attack and rebar corrosion. This paper discusses the evaluation on the durability of reinforced concrete structures covered creek for road vehicle.

• 대한화학회지
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• 제39권1호
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• pp.71-75
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• 1995

Tricarbonyl(2-methyl-1-phenylpentadienyl)iron(+1) hexafluorophosphate 양이온이 hexafluorophosphoric acid를 사용한 tricarbonyl(4-methyl-5-hexadien-1-ol)iron의 양성자 첨가반응에 의해 얻어졌다. 그 양이온과 $H_2o$, dimethyl cuprate, diphenylacetylenyl cuprate, 그리고 cyclohexanone의 enolate와의 반응은 그것들에 대응하는 (η4-1,3-diene)Fe(CO)3를 형성시켰다. 친핵체의 공격에 있어서의 위치 선택성은 주로 입체효과의 결과인 것으로 보인다.

• 대한가정학회지
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• 제34권4호
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• pp.403-414
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• 1996

The softening of the femented vegetables and the fruits was resulted from the degradation of pectin substances, cellulose, hemicellulose by polygalacturonase(PG), pectinesterase(PE), Cx-cellulase, $\beta$-galctosidase. The conversion of insoluble pectin to soluble pectin in cell wall-middle lamella was a major factor in the changes of firmness. Ca2+ was substantially increased firmness. However, Ca2+ could be removed from cell wall by chelating agents such as oxalic acid and citric acid. And Ca2+ was replaced with Na+ by ion exchange reaction. Ca2+ deficient tissue was vulnerable to attack by PG. Preheating treatment and Ca2+ addition is most effective in inhibiting the vegetable food softening and in increasing middle lamella-cell wall regidity, which PE activation by preheating treatment and Ca2+ addition could created more anionic carboxyl groups for cationic materials binding such as Ca2+ and chitosan and for polypectategel formation. Excessive demethylation by PE was associated with loosening of middle lamella cell wall components and softening.

• Bulletin of the Korean Chemical Society
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• 제15권9호
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• pp.729-732
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• 1994

The acid-promoted cleavage of the E-and Z-isomers of 1-phenyl-6-neopentyl-1,3,4-trimethyl-1-silacyclohe x-3-ene(II) under various conditions gave clean and nearly quantitative formation of the ring-opened 2,3,7,7-tetramethyl-5-(X)silyl-1-octene products (X=OMe, Cl, OH). The possible mechanism for the formation of the ring-opened products was suggested that the initial protonation of II at C-4 would give a carbocation oriented so that they are ${\beta}$ to the silicon atom, and the subsequent nucleophilic attack at silicon would give rise to the observed products (VI, VII, VIII).

• The Plant Pathology Journal
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• 제38권2호
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• pp.146-158
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• 2022

Changes in physiological and biochemical patterns in lucerne plants caused by the presence of 'Candidatus Phytoplasma australasia', which is one of the significant pathogens causing yield losses in lucerne plants, were investigated. Significant differences were evident in total chlorophyll, chlorophyll a, chlorophyll b, and protein amounts between 'Ca. Phytoplasma australasia'-positive and negative lucerne plants. Stress-related metabolites such as phenol, malondialdehyde, and proline accumulations in 'Ca. Phytoplasma australasia'-positive plants were remarkably higher than those of phytoplasma-negative plants. As a response to disease attack, phytoplasma-positive plants exhibited higher antioxidant enzymes (peroxidase and catalase) and nonenzymatic metabolite responses such as jasmonic and salicylic acids. We state that partial disease responses were revealed for the first time to breed resistant lucerne lines infected by 'Ca. Phytoplasma australasia'.

• 한국농공학회논문집
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• 제57권4호
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• pp.11-19
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• 2015

The important properties of EVA (ethylene vinyl acetate) redispersible polymer was waterproof, densification of internal pore space of concrete and ball bearing and micro filler. Also, the significant role of polypropylene(PP) fiber was crack control and blockade of movement for deterioration factors. The most studies for EVA were limited in the field of mortar and PP fiber reinforced concrete had been studied in the state of being restricted unit water content, rich mix and mixing much of the fiber without considering construction site. Therefore, the control mix design were applied in ready mixed concrete using 10 % fly ash of total cement weight used in batch plant. On the basis of control mix design, EVA contents ranging from 0 % to 10 % of total cement weight and PP fiber contents ranging from 0 % to 0.5 % of EVA concrete volume were used in the mix designs. The results showed the maximum compressive strength value was measured at EVA 5.0 % and PP fiber 0.1 %, the minimum water absorption ratio was at EVA 10 % and PP fiber 0 %, the durability factor for freezing and thawing resistance was at EVA 5.0 % and PP fiber 0.3 % and the minimum weight reduction ratio of resistance to sulfuric acid attack was at EVA 10 % and PP fiber 0.5 % after curing age 42days. Meanwhile, From these results, PP fiber reinforced EVA concrete would be very benefit, if each optimal mix types were used in hydraulic structures, underground utilities and agricultural structures.

• 콘크리트학회논문집
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• 제14권3호
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• pp.409-419
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• 2002

Nowadays, antiwashout underwater concrete is widely used for constructing underwater concrete structures but they, especially placed in marine environment, can be easily attacked by chemical ions such as SO$\^$2-/$\_$4/ Cl$\^$-/ and Mg$\^$2＋/, so the quality and capability of concrete structures go down. In this paper, to solve and improve those matters, flyash and GGBFS(ground granulated blast furnace slag) were used as partial replacements for ordinary portland cement. As results of experiments for fundamental properties of antiwashout underwater concrete containing 10, 20, 30％ of flyash and 40, 50, 60 ％ of GGBFS respectively, setting time, air contents, suspended solids and pH value were satisfied with the "Standard Specification of Antiwashout Admixtures for Concrete" prescribed by KSCE, and also slump flow, efflux time and elevation of head were more improved than that of control concrete. From the compressive strength test, it was revealed that the antiwashout underwater concrete containing mineral admixtures(flyash and GGBFS) is more effective for long term compressive strength than control concrete. An attempt to know how durable when they are under chemical attack has also been done by immersing in chemical solutions that were x2 artificial seawater, 5 ％ sulphuric acid solution, 10％, sodium sulfate solution and 10％ calcium chloride solution. After immersion test for 91days, XRD analysis was carried out to investigate the reactants between cement hydrates and chemical ions and some crystalline such as gypsum ettringite and Fridel′s salt were confirmed.

• 농약과학회지
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• 제7권2호
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• pp.155-158
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• 2003

2-Imino-1,3-thiazloine 1은 새로운 작용기작에 의하여 벼도열병원균에 대하여 선택적인 항균력을 나타낸다. 화합물 1의 C-2 위치의 imino기에 cyano 기가 치환된 새로운 화합물 2-cyanoimino-1,3-thiazoline 유도체 2를 합성하였다. Cyano 기의 강한 전자끌기와 더불어 1,3-thiazoline 고리의 황 및 질소원자의 비공유전자쌍은 2-imino-1,3-thiazloine 계열의 생물활성에 영향을 줄 것으로 예상되었다. Thiourea 4 의 $\gamma$-chloro-$\beta$-ketoacetoacetanilide 3에 대한 위치 특이적인 친핵적 공격 및 산촉매 하의 탈수에 의해서 2가 생성되었다.

• The Plant Pathology Journal
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• 제21권3호
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• pp.288-292
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• 2005

Pathogenesis-related protein-1a (PR-1a) is strongly induced in tobacco plants by pathogen attack, exogenous salicylic acid (SA) application and by other developmental processes. In order to develop a rapid screening system for the selection of plant defense-inducing compounds originated from various sources, we have transformed tobacco Samsun NN plants with a chimeric construct consisting of GUS $(\beta-glucuronidase)$. In the $T_1$ generation, three transgenic lines having stable GUS expression were selected for further promoter analysis. Using GUS histochemical assay, we observed strong GUS induction driven by PR-1a promoter in PR1a-GUS transgenic tobacco leaves in response to the exogenous application of SA or benzol (1,2,3) thiadiazole-7-carbothioic acid S-methyl ester (BTH), a SA­derivative compound. In addition, GUS expression was maintained locally or systemically in PR1a-GUS transgenic line $\#5\;T_2$ generation) until after 3 days when they were treated with same chemicals. Our results suggested that the PR1a-GUS reporter gene system in tobacco plants may be applicable for the large-scale screening of defense-inducing substances.