• Macromolecular Research
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• 제12권2호
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• pp.213-218
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• 2004

We have performed dispersion polymerization of acrylamide in tert-butyl alcohol/water mixture-using hydroxypropyl cellulose and ammonium persulfate as the stabilizer and the initiator, respectively - to study the effects that the concentration of monomer, initiator, and stabilizer, the tert-butyl alcohol/water ratios as polymerization media, and the reaction temperature have on, among other things, the polymerization kinetics, particle sizes, and molecular weights. The polymerization rate increased upon increasing the concentration of the monomer, initiator, and stabilizer, the water content in the tert-butyl alcohol/water media, and the polymerization temperature. The average particle size of the lattices increased upon increasing the concentration of initiator, the polymerization temperature, and the water content in the tert-butyl alcohol/water media, but it decreased upon increasing the concentration of monomer and stabilizer. The viscosity-average molecular weight increased upon increasing the concentration of monomer and stabilizer and the water content in the tert-butyl alcohol/water media, but it decreased upon increasing both the concentration of initiator and the polymerization temperature.

• 폴리머
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• 제24권5호
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• pp.629-637
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• 2000

Hydroxypropyl cellulose와 ammonium persulfate를 각각 입자안정제와 개시제로 사용하여 t-butyl alcohol/$H_2O$ 흔합 분산매에서 아크릴아미드의 분산중합을 다양한 중합 조건하에서 수행하여 생성되는 poly(acrylamide)(PAM) 라텍스의 평균입자경, 라텍스 고분자의 점도평균분자량, 수용화 정도 등을 관찰하였다. 일반적으로 PAM 라텍스의 평균입자경은 개시제의 농도, 분산매 중 물의 농도, 중합 온도가 증가함에 따라, 또는 단량체의 농도, 입자안정제의 농도가 감소함에 따라 증가하였다. 라텍스상태로 얻어진 PAM 고분자의 점도평균분자량은 단량체의 농도, 입자 안정제의 농도, 분산매 중 물의 농도가 증가함에 따라, 또는 개시제의 농도, 중합 온도가 감소함에 따라 증가하였다. 본 연구에서 얻어진 PAM 라텍스는 0.1~0.5 $\mu\textrm{m}$의 평균입자경과 470000~2080000의 점도평균분자량을 나타내었으며 이들은 물에서 순간적으로 수용화되었다.

• 대한방사성의약품학회지
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• 제2권1호
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• pp.17-21
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• 2016

Alkali metal fluoride sources (MFs) such as potassium fluoride (KF) have been widely used as a fluoride source in the nucleophilic displacement reaction. However, they have low solubility and nucleophilicity in most of the organic solvents. Bulky fluoride sources such as tetrabutylammonium fluoride (TBAF) were substituted for MFs to improve these properties. However, hygroscopic property of TBAF makes it less convenient for handling as well as its strong basic property can make the side-reaction occur. Recently, novel fluoride sources have been developed to solve these problems. In this paper, we would like to introduce coordinated fluoride sources as a new fluoride sources such as tetrabutylammonium tetra(t-butyl alcohol)-coordinated fluoride, crown ether metal complex fluoride, and various bulky alcohols coordinated fluoride complexes. In particular, bulky alcohol coordinated fluoride source could generated by the controlled hydrogen-bonded of fluoride with alcohols and these fluoride sources have better stability and reactivity with showing low hygroscopic property. The study of these fluoride sources will help to understand the characteristic of [$^{18}F$]fluoride for increasing the radiochemical yield in the [$^{18}F$]radiofluorination.

• Applied Biological Chemistry
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• 제13권3호
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• pp.187-191
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• 1970

간장의 발효에 지대한 영향을 미칠수 있는 고농도 식염내성 효모의 분리를 시도 했던바 발효기의 샘표간장덧 으로부터 6주의 효모를 분리선정하고 이들의 균학적성질을 살펴 동정함과 동시에 내염성및 간장의 풍미에 미치는 영향에 대하여 실험한 결과는 다음과 같다. (1) 고농도식염내성효모로 선정된 6주의 효모중 $T_3$균주는 Saccharomyces cerevisiae group II형, $T_5$와 $T_{11}$은 Debaryomyces nicotianae형, $T_8$은 Saccharomyces chevalieri형, $T_9$은 Saccharomyces rouxii형, $T_{10}$은 Saccharomyces rosei형으로 각각 동정 되었다. (2) 고농도의 식염 함유 배지의 경우 고체배지에서보다 액체배지에서 이들 효모의 내염성이 더욱 높았다. (3) 선정된 균주 모두가 무염배지에서 보다 $5{\sim}23%$의 식염함유 배지에서 잘생육하는 효염성의 효모들이였다. (4) $T_3,\;T_8,\;T_9,\;T_{10}$등의 균주는 배지의 식염농도 28%까지 생육하였으며 $T_5$와 $T_{11}$은 32%까지 생 육하였다. (5) 이들중 $T_9$의 균주가 Alcohol발효력이 가장 강했으며 발효생성물의 풍미도 가장 우수하였다. 또한 $T_5$와 $T_{11}$은 Mold취를 생성하며 산막을 형성하는 유해 효모였다.

• Bulletin of the Korean Chemical Society
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• 제23권1호
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• pp.123-131
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• 2002

Solvolyses rate constant of 1- and 2- naphthoyl chlorides (1 and 2) are reported for aqueous binary mixtures with methanol, ethanol, fluorinated alcohol, acetonitrile and dioxane. Kinetic solvent isotope effects (KISE) in methanol and product selectivities (S) of 2-naphthoyl chloride (2) in alcohol-water are also reported. Dispersions in Grunwald-Winstein correlations $(r{\leq}0.901)$ are discussed by multiple regression analysis incorporating ionizing power $(Y_{Cl})$ scale and rate-rate profiles. Major causes for these phenomena are investigated as an aromatic ring solvation effects, in conjunction with weakly nucleophilic solvation effects ($S_N2$ character), for solvolyses of 1 and for solvolyses of 2, as dual reaction channels, described as $S_N1$-$S_N2$ and $S_AN$-$S_N2$ processes. Distinct border lines between the two pathways are derived from solvolyses rates of 2 in 18 solvent using the results of $log(k/k_o)=mY_{Cl}+lN_T+hI$ plot with values of 1.13 for m, 0.37 for l and 0.15 for h value in 5 aqueous fluorinated alcohol mixtures. Using rate-product correlation, the validity of a third order model based on a general base catalyzed by solvent and contribution from these rate constants, $k_{aa},\;k_{aw}$ and $k_{aw}$, are investigated for $S_AN$-$S_N2$ solvolyses of 2 favored in more rich alcohol media and gradual addition of water to alcohol solvent shows a great shift away from stoichiometric solvation to predominantly medium effects. Rate-rate correlation between solvolyses of 2 and trimethyl acetylchloride (5) with alkyl group in the 29 aqueous solvent mixtures shows appreciable linearity (slope = 0.84, r = 0.987), caused by the same pathway ($S_N1$-$S_N2$ process), even if this correlation coincides with appreciable dispersion (different solvation effect).

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2377-2381
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• 2007

Solvolyses of 3,4-dimethoxybenzenesulfonyl chloride (DSC) in water, D2O, CH3OD, and in aqueous binary mixtures of acetone, acetonitrile, 1,4-dioxane, ethanol, methanol, and 2,2,2-trifluoroethanol (TFE) have been investigated at 25.0 oC. Kinetic solvent isotope effects (KSIE) in water and in methanol and product selectivities in alcohol-water mixtures are also reported. The Grunwald-Winstein plot of first-order rate constants for the solvolyic reaction of DSC with YCl shows marked dispersions into separated lines for various aqueous mixtures. With use of the extended Grunwald-Winstein equation, the l and m values obtained are 1.12 and 0.58 respectively for the solvolyses of DSC. The relatively large magnitude of l is consistent with substantial nucleophilic solvent assistance. From Grunwald-Winstein plots the rate data are dissected approximately into contributions from two competing reaction channels. This interpretation is supported for alcohol-water mixtures by the trends of product selectivities, which show a maximum for ethanol-water mixtures. From the KSIE of 1.45 in methanol, it is proposed that the reaction channel favored in methanolwater mixtures and in all less polar media is general-base catalysed and/or is possibly (but less likely) an addition-elimination pathway. Also, the KISE value of 1.35 for DSC in water is expected for SN2-SN1 processes, with minimal general base catalysis, and this mechanism is proposed for solvolyses in the most polar media.

• KSBB Journal
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• 제15권2호
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• pp.134-138
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• 2000

알콜증류폐액에 빵효모를 배양하는 중에 glucose와 ammo-nium을 자동첨가함으로써 폐액배양액의 균체농도를 높여서 알콜증류폐액의 이용성을 증가시키고자 하였다. 배양중에 glucose를 공급하여 줌으로서 공급하지 않은 경우보다 1.3배 더 높은 균체농도를 얻었으며, glucose와 (NH4)2SO4를 공급하여 줌으로써 5.8배 더 높은 균체농도를 얻었다. Glucose의 경우에는 배양액의 DO를 제어파라미터로 하는 제어방법을 사용하여 자동첨가하고, ammonium의 경우에는 pH조정제로서 NH4OH을 사용함으로서 pH제어기에 의하여 자동으로 공급되도록 배양하였다. 배양결과 증식의 정체없이 배양 22.5시간후에 최대 12.0 g/L의 건조균체량에 도달하였으며, 균의 최대비증식속도는 0.18 hr-1였고, 대당균체수율이 약 0.54g/gdldjTdmamfh glucose의 첨가가 경제적이라고 생각되었다. 증균배양으로 폐액배양액의 COD를 약 22% 더 감소시킬 수 있었다.

• 미생물학회지
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• 제36권3호
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• pp.228-235
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• 2000

지금까지의 Phanerochaete chrysosporium을 이용한 Lignin Peroxidase(LiP) 의 생산은 최적화 되지 못한 배양 조건으로 인해 매우 낮은 활성만을 얻을수 있었으며. 그 배양조건 또한 100% 산소의 주입을 요하는 일반적으로는 재현하기 어려운 조건이었다. 본 연구에서는 Phanerochaete chrysosporium PSBL-1 균줄르 이용, 다양한 배양조건의 변화를 통해 LiP의 과량생산과 그에 따른 isozyme 조성의 변화를 확인하고자 하였다. 최종적으로 $Mn^{2+}$를 제거한 배지에 질소 원인 diammonium을 48mM 로 첨가하고, 안정제로서 veratryI alcohol을 2 mM로 첨가하여, sponge에 의한 고착배양을 실시한 결과 1,800 units/l의 LiP가 생산되었다. 이러한 활성의 증가는 기존에 보고된 PSBL-1 균주의 LiP 최대 생산량인 700units/l와 비교 , 약 2.57배의 생산량 증대를 나타낸다. 생산된 LiP isozyme 분석결과 $Mn^{2+}$(2.73 mM)와 diammonium(48 mM)을 첨가하였을 경우 H1 isozyme의 과량 생산이 확인되었다. 생산된 LiP(0.4 units)를 이용하여 각각의 아조계 염료(acid yellow 9, congo red, orange II; each 50$\mu$M)에 대한 탈생능을 확인한 결과, 2분 이내에 이들 염료에 대한 탈색이 이루어지는 것을 확인할 수 있었고 분해 산물이 축적되는 것을 확인할 수 있었다.

• 대한간호학회지
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• 제36권8호
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• pp.1315-1323
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• 2006

Purpose. The present study was intended to compare difference in research variables between delinquent adolescents and student adolescents, and to analyze discriminative factors of delinquent behaviors among Korean adolescents. Methods. The research design of this study was a questionnaire survey. Questionnaires were administered to 2,167 adolescents (1,196 students and 971 delinquents), sampled from 8 middle and high school and 6 juvenile corrective institutions, using the proportional stratified random sampling method. Statistical methods employed were Chi-square, t-test, and logistic regression analysis. Results. The discriminative factors of delinquent behaviors were smoking, alcohol use, other drug use, being sexually abused, viewing time of media violence and pornography. Among these discriminative factors, the factor most strongly associated with delinquency was smoking (odds ratio: 32.32). That is, smoking adolescent has a 32-fold higher possibility of becoming a delinquent adolescent than a non-smoking adolescent. Conclusions. Our findings, that smoking was the strongest discriminative factor of delinquent behavior, suggest that educational strategies to prevent adolescent smoking may reduce the rate of juvenile delinquency. Antismoking educational efforts are therefore urgently needed in South Korea.

• Asian Pacific Journal of Cancer Prevention
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• 제14권4호
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• pp.2217-2220
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• 2013

Background: Knowledge regarding risk factors and primary signs of oral cancer in the general population can help them to avoid risky behaviour and seek timely advice from a physician. The aim of this study was to survey adult knowledge about risk factors and signs of oral cancer in Shiraz Dental University. Materials and Methods: In this descriptive cross-sectional study using an investigator-made questionnaire, 783 adults who were referred to Shiraz Dental University participated. Questionnaire data were analyzed by ANOVA and T-test. Results: The results showed that 32.3% of participants were aware of oral cancer and gained their knowledge from the media. The risk factors mentioned by these participants was as follows: sunlight 30.8%, hot and peppery food 40.7%, alcoholic drinks 47.4% and smoking 73.6% (there was significant relationship for drinking alcohol and gender, education and times of using dental service, p<0.05). They also mentioned the primary signs of oral cancer as follows: red patch without pain 27.8%, white patch without pain 13.5% and prolong scarring without pain 56.7% (there was significant relationship between these three signs and education and times of using dental service, p<0.05). The mean knowledge about the risk factors and signs of oral cancer were 1.94 from 5 with 1.14 standard deviation and 0.96 from 3 with 0.93 standard deviation. Conclusions: The observed low level of knowledge of people regarding both risk factors and signs of oral cancer emphasizes the need for more efforts to be made about the above mentioned issues by the media.