• Bulletin of the Korean Chemical Society
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• 제29권10호
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• pp.1911-1914
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• 2008

Second-order rate constants (kN) have been measured for Michael-type addition reactions of a series of alicyclic secondary amines to 1-phenyl-2-propyn-1-one (2) in MeCN at 25.0 ${\pm}$ 0.1 ${^{\circ}C}$. All the amines studied are less reactive in MeCN than in $H_2O$ although they are more basic in the aprotic solvent by 7-9 p$K_a$ units. The Bronsted-type plot is linear with $\beta_{nuc}$ = 0.40, which is slightly larger than that reported previously for the corresponding reactions in $H_2O$ ($\beta_{nuc}$ = 0.27). Product analysis has shown that only E-isomer is produced. Kinetic isotope effect is absent for the reactions of 2 with morpholine and deuterated morpholine (i.e., $k^H/k^D$ = 1.0). Thus, the reaction has been concluded to proceed through a stepwise mechanism, in which proton transfer occurs after the rate-determining step. The reaction has been suggested to proceed through a tighter transition state in MeCN than in H2O on the basis of the larger $\beta_{nuc}$ in the aprotic solvent. The nature of the transition state has been proposed to be responsible for the decreased reactivity in the aprotic solvent.

• Journal of Ginseng Research
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• 제34권2호
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• pp.104-112
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• 2010

Fermented red ginseng (FRG) was prepared by inoculating 0.1% Lactobacillus fermentum NUC-C1 and fermenting them at $40^{\circ}C$ for 12 hours. The ginsenoside contents of FRG were increased compared with those of red ginseng (RG). Moreover, the levels of the ginsenosides Rg2, Rg3, and Rh2 in FRG increased significantly. In an oral glucose tolerance test (OGTT), blood glucose levels were lower in animals fed with RG and FRG extracts than in normal controls. In particular, FRG extracts in OGTT were superior to RG extracts. The antidiabetic effects of FRG in streptozotocin (STZ)-induced diabetic rats were investigated. Rats were divided into four groups: normal control, diabetes mellitus (DM), FRG administered at 100 mg/kg, and FRG administered at 200 mg/kg groups. FRG extracts were orally administered to each treatment group for 3 weeks, and blood glucose, insulin, and lipid levels of each group were determined. Orally administered FRG extracts significantly reduced blood glucose levels and increased plasma insulin levels in diabetic rats. Additionally, the activities of disaccharidases, including sucrase, lactase, and maltase, were decreased significantly in the FRG groups. FRG groups also had reduced triglyceride and total cholesterol levels, compared with the DM group. These results suggest that FRG may have antidiabetic effects in STZ-induced diabetic rats.

• Bulletin of the Korean Chemical Society
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• 제34권8호
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• pp.2325-2329
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• 2013

Second-order rate constants $k_N$ have been measured for reactions of benzyl 2-pyridyl thionocarbonate (4b) and t-butyl 2-pyridyl thionocarbonate (5b) with a series of cyclic secondary amines in MeCN at $25.0{\pm}0.1^{\circ}C$. The $k_N$ values for the reactions of 4b and 5b have been compared with those reported previously for the corresponding reactions of benzyl 2-pyridyl carbonate (4a) and t-butyl 2-pyridyl carbonate (5a) to investigate the effect of changing the electrophilic center from C=O to C=S on reactivity and reaction mechanism. The thiono compound 4b is more reactive than its oxygen analogue 4a. The Br${\o}$nsted-type plots for the reactions of 4a and 4b are linear with ${\beta}_{nuc}=0.57$ and 0.37, respectively. The reactions of 4a were previously reported to proceed through a concerted mechanism, while those of 4b in this study have been concluded to proceed through a stepwise mechanism with formation of an intermediate being the rate-determining step on the basis of the ${\beta}_{nuc}$ value of 0.37. Enhanced polarizability upon changing the C=O in 4a by C=S has been suggested to be responsible for the reactivity order and the contrasting reaction mechanisms. In contrast, the reactivity of 5a and 5b is similar, but they are much less reactive than 4a and 4b. Furthermore, the reactions of 5a and 5b have been concluded to proceed through the same mechanism (i.e., a concerted mechanism) on the basis of linear Bronsted-type plots with ${\beta}_{nuc}=0.45$ or 0.47. It has been concluded that the strong steric hindrance exerted by the t-Bu in 5a and 5b causes a decrease in their reactivity and forces the reactions to proceed through a concerted mechanism.

• Journal of the Korean Physical Society
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• 제73권12호
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• pp.1821-1826
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• 2018

Uniformity is a key feature of state-of-the-art infrared focal planed array (IRFPA) and infrared imaging system. Unlike traditional infrared telescope facility, a ground-based infrared radiant characteristics measurement system with an IRFPA not only provides a series of high signal-to-noise ratio (SNR) infrared image but also ensures the validity of radiant measurement data. Normally, a long integration time tends to produce a high SNR infrared image for infrared radiant characteristics radiometry system. In view of the variability of and uncertainty in the measured target's energy, the operation of switching the integration time and attenuators usually guarantees the guality of the infrared radiation measurement data obtainted during the infrared radiant characteristics radiometry process. Non-uniformity correction (NUC) coefficients in a given integration time are often applied to a specified integration time. If the integration time is switched, the SNR for the infrared imaging will degenerate rapidly. Considering the effect of the SNR for the infrared image and the infrared radiant characteristics radiometry above, we propose a-wide-dynamic-range NUC algorithm. In addition, this essasy derives and establishes the mathematical modal of the algorithm in detail. Then, we conduct verification experiments by using a ground-based MWIR(Mid-wave Infared) radiant characteristics radiometry system with an Ø400 mm aperture. The experimental results obtained using the proposed algorithm and the traditional algorithm for different integration time are compared. The statistical data shows that the average non-uniformity for the proposed algorithm decreased from 0.77% to 0.21% at 2.5 ms and from 1.33% to 0.26% at 5.5 ms. The testing results demonstrate that the usage of suggested algorithm can improve infrared imaging quality and radiation measurement accuracy.

• Journal of Radiation Protection and Research
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• 제33권4호
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• pp.167-172
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• 2008

최근 한양대학교에서는 고해상도 연속절단면 컬러해부영상자료를 이용하여 표준한국인 성인남성 체적소 모델 HDRK-Man을 개발하였다. HDRK-Man 은 기존의 다른 모델들과 마찬가지로 누워있는 인체의 영상을 사용하여 제작하였기 때문에 등과 엉덩이 부분이 납작하다는 문제가 있다. 이러한 문제를 해결하기 위하여 본 연구에서는 HDRK-Man 체적소 모델을 변형이 용이한 면(surface) 모델로 변환하였고 전신외형을 보정한 후 외형 보정이 선량 계산에 미치는 영향을 평가하였다. 면 모델로의 변환 작업은 상용 소프트웨어인 $3D-DOCTOR^{TM}$, $Rapidform^{(R)}$2006, $Rhinoceros^{(R)}$4.0을 사용하였고, 전신외형의 보정작업은 $MAYA^{(R)}$8.5을 사용하였다. 면의 형태로 변환된 모델은 곧바로 몬테칼로 선량계산에 사용한 수 없으므로, 다시 체적소 모델로 변환하여 선량계산을 수행하였다. MCNPX 몬테칼로 코드를 이용하여 보정 전후의 유효선량을 계산하여 비교해 본 결과 전체적으로 큰 차이는 없었으며, 예상대로 전 (AP), 좌(LLAT), 우(RLAT) 방향에 비하여 후 (PA)방향에서 상대적으로 가장 큰 차이를 보였다. 본 연구를 통하여 변환된 면(surface) 모델은 방사선 방호 분야에서 활용할 수 있는 다양한 자세를 갖는 변형된 인체모델 개발에 사용될 수 있을 것으로 기대된다.

• 한국식품과학회지
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• 제43권2호
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• pp.200-205
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• 2011

본 연구에서는 문헌을 통하여 항산화 혹은 항염증 활성을 가지는 6종의 생약재와 이들 생약재를 혼합하여 제조한 생약복합제의 항산화 및 항염증 활성을 측정하였다. 총 폴리페놀 함량은 어성초, 홍화, MIX-2 에탄올추출물이 각각 58.98, 60.79, 57.74 mg/g의 함량으로 다른 시료들 보다 높게 측정되었다. 또한 플라보노이드 함량도 어성초(HC), 홍화(CT), MIX-2에탄올추출물이 각각 36.86, 19.42, 14.74 mg/g으로 높게 측정되었다. 단일 생약재와 생약복합제 에탄올추출물의 라디칼 소거능을 측정한 결과 DPPH 라디칼의 RC50 값은 어성초, 홍화, MIX-2 에탄올추출물에서 각각 69.64, 50.70, $63.49{\mu}g/mL$로 추출물 가운데 우수한 DPPH 라디칼 소거능을 보였고, ABTS 라디칼의 $RC_{50}$ 값도 어성초, 홍화, MIX-2가 각각 24.06, 18.91, $41.61{\mu}g/mL$로 DPPH 라디칼 소거능과 유사한 경향을 보였다. 시료들의 항염증 효능을 측정하기 위해 5-LO 및 COX-2 효소 저해활성을 측정한 결과 단일 생약재 에탄올추출물보다 생약복합제 에탄올추출물이 5-LO와 COX-2 효소를 동시에 저해하는 효과가 증가되는 것으로 나타났다. 염증유발 효소 저해활성이 우수했던 생약복합제 에탄올추출물들의 NO 소거활성을 비교한 결과, MIX-2 에탄올추출물이 $50{\mu}g/mL$의 농도에서부터 유의적으로 NO의 생성을 저해하는 것을 확인하였다. 따라서 단일 생약재 보다는 생약복합제가 서로 혼합되면서 시너지 효과가 나타나는 것으로 생각되며 앞으로 명확한 기전에 대한 연구들이 지속된다면 기능성 식품 소재로서의 이용이 가능할 것으로 생각된다.

• 한국식품과학회지
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• 제43권5호
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• pp.624-632
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• 2011

본 연구에서는 민간 및 한방에서 관절염 치료 처방제로 널리 사용되고 있는 한방처방제 16종을 선정하여 향후 관절염 예방 및 치료용 기능성식품의 개발 기초 자료로 활용하기 위해 한방처방제로부터 물, 에탄올 및 효소처리추출물을 제조하고 그들의 항산화 및 항염증활성을 in vitro assay system을 사용하여 측정하였다. 16종 한방처방제의 각 추출물의 폴리페놀 함량은 10.03-78.03 mg/g의 범위를 나타내었으며, 이 중 마행의감탕(7번)의 에탄올추출물이 78.03 mg/g으로 16종의 한방처방제 중 가장 높은 폴리페놀 함량을 보였다. 총 플라보노이드 함량의 경우 총 폴리페놀 함량의 결과와 달리 효소추출물에서는 폴리페놀 추출 함량이 낮아지거나 비슷한 수치를 보였지만 총 플라보노이드 함량의 경우 마행의감탕(7번)을 제외한 나머지 15종의 한방처방제에서 열수 및 에탄올추출물보다 효소추출물에서 플라보노이드 함량이 증가하는 것을 확인하였다. 한편, 마행의감탕(7번) 추출물에서 DPPH 및 ABTS 라디컬 포착활성과 COX-2 저해활성도 가장 높게 나타난 반면, 효소추출물에서는 의의인탕(14번)이 가장 높은 COX-2 저해활성을 나타내었다. 이러한 결과를 종합해 볼 때 마행의감탕 및 의의인탕을 관절염 치료 한방처방제로 개발할 가능성이 높다고 생각되며, 향후 보다 상세한 그들의 항산화 및 항염증활성을 조사할 필요가 있다고 생각된다.

• Bulletin of the Korean Chemical Society
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• 제29권12호
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• pp.2509-2512
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• 2008

• Bulletin of the Korean Chemical Society
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• 제34권7호
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• pp.2036-2040
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• 2013

Reactions of 4-nitrophenyl 2-thiophenecarboxylate (1a-e) with $R_2NH/R_2NH{_2}^+$ in 20 mol % DMSO (aq) have been studied kinetically. The $2^{nd}$ order kinetics, ${\beta}_{nuc}$ = 0.88-0.98, and linear Hammett and Yukawa-Tsuno plots observed for these reactions indicate an addition-elimination mechanism in which the $2^{nd}$ step is rate limiting. The ${\beta}_{nuc}$ value increased with a stronger electron-withdrawing 5-thienyl substituent, the Hammett plots are linear except for X = MeO, and Yukawa-Tsuno plots are linear with ${\rho}$ = 0.79-1.32 and r = 0.28-0.93, respectively. The ${\rho}$ value increased and r value decreased with a stronger nucleophile, indicating an increase in the electron density at the C=O bond and a decrease in the resonance demand. These results have been interpreted with enhanced N-C bond formation in the transition state with the reactivity increase.

• 한국축산식품학회지
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• 제37권2호
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• pp.175-180
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• 2017

The objectives of this study were: i) to detect the presence of Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) in raw milk, cheese, beef minced meat, and chicken meat samples; ii) to evaluate the antimicrobial susceptibility of the isolates; and iii) to determine clonal relation among the isolates by using pulsed-field gel electrophoresis (PFGE) method. Therefore, a total of 160 food samples were randomly collected between August 2014 and May 2015 in Hatay province, located in the southern Turkey. Twenty (12.5%) of the samples were found to be contaminated with S. aureus. A total of 40 isolates from the 20 positive samples were confirmed to be S. aureus by multiplex PCR based on 16S rRNA and nuc gene. The mec A gene was not detected in any of the S. aureus strains. In the present study, 39 out of 40 (97.5%) isolates were found to be resistant to one or more antibiotics. All of isolates were susceptible to gentamicin, oxacillin, and vancomycin. The highest resistance rate was detected in penicillin (95%) and ampicillin (92.5%), followed by tetracycline (30%), erythromycin (20%), ciprofloxacin (12.5%). Nine major patterns were determined by PFGE. In 6 of these patterns, thirty-six strains (90%) had identical PFGE profiles.