• 한국세라믹학회지
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• 제43권10호
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• pp.595-600
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• 2006

The preparation of $\beta$-SiAlON powder by SHS in the system of $Si-Al-SiO_2-NH_4F(\beta-Si_3N_4)$ was investigated in this study. In the preparation of SiAlON powder, the effect of gas pressure, compositions such as Si, $NH_4F$, \beta-Si_3N_4$ and additive in mixture on the reactivity were investigated. At 50 atm of the initial inert gas pressure in reactor, the optimum composition for the preparation of pure $\beta$-SiAlON was $3Si+Al+2SiO_2+NH_4F$. The $\beta$-SiAlON powder synthesized in this condition was a single phase $\beta$-SiAlON with a rod like morphology.

• 한국식품과학회지
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• 제31권5호
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• pp.1164-1170
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• 1999

찰성(waxy) 및 메성(non-waxy) 보리로 부터 ${\beta}-glucan$을 분리, 정제하였고 정제한 ${\beta}-glucan$의 표면구조, DSC특성, 고유점도를 비교하였으며 ${\beta}-glucan$의 첨가가 보리전분의 호화특성에 미치는 영향을 조사하였다. 보리의 총 ${\beta}-glucan$ 함량은 찰성보리가 6.5%, 메성보리가 5.3%였다. 알칼리 추출 후 1차 정제한 crude ${\beta}-glucan$의 ${\beta}-glucan$ 함량은 찰성보리가 62.9%, 메성보리가 59.2%였으며, 수율은 찰성보리가 5.54%로 메성보리의 수율 3.34%보다 높았다. 2차 정제한 ${\beta}-glucan$의 수율도 찰성이 4.46%로 메성의 2.59%보다 높았다. SEM으로 관찰한 정제 ${\beta}-glucan$의 표면구조는 섬유상의 fibril들이 서로 얽힌 망상의 배열을 이루고 있었다. DSC로 측정한 융점은 찰성보리 ${\beta}-glucan$이 $184.6^{\circ}C$로 메성의 $180.3^{\circ}C$ 보다 높았고 겔화에 의한 상전이는 $68^{\circ}C$와 $84^{\circ}C$ 부근에서 2개의 흡열피크로 나타났으며 찰성 ${\beta}-glucan$의 엔탈피 값이 작았다 정제한 ${\beta}-glucan$의 고유점도는 메성보리보다 찰성보리 ${\beta}-glucan$이 더 컸다. 보리전분에 ${\beta}-glucan$을 첨가하여 호화시켰을 때 상승작용으로 비스코그램의 점도를 증가시켰으며 그 효과는 메성전분에서 현저하였다.

• 한국안전학회지
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• 제9권3호
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• pp.22-27
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• 1994

For the $\beta$=1 specimen with constant thickness, Crack growth rate is smoothly increasing in the a-N curve. On the other hand for $\beta$=2 specimen with various thickness, the inflection point is observed in crack growth rate near the thickness interface. da/dN before the inflection point is increased, and da/dN after the point is decreased, compared to the $\beta$=1 specimen. da/dN near the thickness interface is approached zero. The descending point was observed earlier as $\beta$ increased. Considering the relation between da/dN and λ, the crack propagation rates for the case of $\beta$ =1 incrased almost linearly, however, the crack propagation rates for $\beta$=2,3 decreased more rapidly near the thickness interface. Additionally, the decreased point in da/dN for $\beta$=3 is farther from the thickness interface than the case for $\beta$ =2.

• 한국미생물·생명공학회지
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• 제19권5호
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• pp.439-443
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• 1991

A strain of Streptomyces sp. isolated from soil was found to produce extra-cellular $\beta$-lactamase associated partially to the cell growth. The $\beta$-lactamase was purified from the culture supernatant through anmonium sulfate fractionation, ion-exchange chromatographies and gel filtration. The final purification fold and recovery yield were 57 and 6.2%, respectively. Molecular weight of the $\beta$-lactamase was estimated to be about 67, 000 by SDS-polyacrylamide gel electrophoresis. The optimal reaction condition was at pH 7-8 and at 35-$45^{\circ}C$. The $K_m$ and $V_{max}$ values of the enzyme for penicillin G were estimated to he 3 mM and $3\times 10^3$ $\mu\textrm{M}$/min/mg protein, respectively. The purified $\beta$-lactamase was classified to the class A enzyme hydrolyzing only penicillin.

• Applied Biological Chemistry
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• 제49권4호
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• pp.270-275
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• 2006

Triterpenoid를 포함하고 있는 $2{\beta},\;3{\alpha}$, 23-trihydroxyrus-12-ene-28-oic acid를 애기마름으로부터 분리하였다. 이것은 pentacyclic triterpenes의 공통 구조를 가지며 amyrin ursolic acid 그룹에 속해 있다. 본 연구에서는 이 화합물의 독성 영향을 인간 간암 세포주인 HepG2에서 조사하였다. $2{\beta},\;3{\alpha}$, 23-trihydroxyrus-12-ene-28-oic acid는 처리한 양에 비례하여 HepG2 세포주에서 독성을 보였다. 그리고 Confocal microscopy 결과는 $2{\beta},\;3{\alpha}$, 23-trihydroxyrus-12-ene-28-oic acid를 HepG2 세포에 처리한 시간에 비례하여 녹색 형광의 증가를 보여주었다. $2{\beta},\;3{\alpha}$, 23-trihydroxyrus-12-ene-28-oic acid는 또한 HepG2 세포의 sub-G1 cell population 뿐만 아니라 DNA 분절(fragmentation) 현상의 증가를 보여 주었다. 이러한 결과는 $22{\beta},\;3{\alpha}$, 23-trihydroxyrus-12-ene-28-oic acid가 HepG2 세포에서 apoptosis를 통한 세포 사멸 유도를 의미한다.

• The Korean Journal of Physiology and Pharmacology
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• 제1권2호
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• pp.161-167
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• 1997

This study compares the subtypes of central beta adrenergic receptors (ARs) of brains of untreated rats with those of imipramine-treated rats. Beta adrenergic receptors were measured by quantitative autoradiography of the binding of $^3H$-dihydroalprenolol ($^3H$-DHA) in coronal sections of rat brain. Repeated treatment of rats with imipramine significantly reduced the binding of $^3H$-DHA to beta-1 AR in many brain areas, especially throughout the cerebral cortex, hippocampus, thalamus, and amygdala. Significant reductions of the binding of $^3H$-DHA to beta-2 AR were not found in any area of the brain. These data suggests that a selective down-regulation of beta-1 AR may be involved in the adaptive changes occurring after prolonged imipramine treatment.

• Journal of the Korean Wood Science and Technology
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• 제41권2호
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• pp.149-157
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• 2013

The octopus type oligo-hydroxypropylene glycol ${\beta}$-D-glucopyranosides were successfully synthesized in this studies: the sterospecific compound of allyl 2, 3, 4, 6-tetra-O-acetyl-${\beta}$-D-glucopyranosides (1) was deacetylated with NaOMe in MeOH lead to allyl-${\beta}$-D-glucopyranoside (2) which was perallylated and followed by hydroboration and subsequent oxidation afforded (3-hydroxy-propyl) 2, 3, 4, 6-tetraO(3-hydroxy-propyl)-${\beta}$-D-glucopyranoside (4). As a result, not only allylpropylene glycol ${\beta}$-D-glucopyranosides (5, 7, and 9) but also hydroxypropylene glycol ${\beta}$-D-glucopyranosides (6, 8, and 10) were synthesized by repeated sequential perallylation followed by hydroboration/oxidation.

• 대한화학회지
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• 제35권5호
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• pp.575-579
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• 1991

6${\beta}$-bromopenicillanic acid(4a)와 p-nitrobenzylbromide, 3-bromophthalide, chloromethylpivalate 및 1-chlorodiethylcarbonate의 반응으로 6${\beta}$-bromopenicillanates(4b~4e)을 합성하였으며, 6${\beta}$-bromopenicillanic acid(4a)와 그의 ester(4b~4e)를 thioglycolic acid와 친핵성 치환반응시켜 새로운 $\beta$-lactam계 화합물인 6-(carboxymethylthio)penicillanic acid(5a)와 그의 ester(5b~5e)를 얻었다.

• Communications for Statistical Applications and Methods
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• 제31권3호
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• pp.263-277
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• 2024

This paper proposes new parameterizations of the tilted beta binomial distribution, obtained from the combination of the binomial distribution and the tilted beta distribution, where the beta component of the mixture is parameterized as a function of their mean and variance. These new parameterized distributions include as particular cases the beta rectangular binomial and the beta binomial distributions. After that, we propose new linear regression models to deal with overdispersed binomial datasets. These new models are defined from the proposed new parameterization of the tilted beta binomial distribution, and assume regression structures for the mean and variance parameters. These new linear regression models are fitted by applying Bayesian methods and using the OpenBUGS software. The proposed regression models are fitted to a school absenteeism dataset and to the seeds germination rate according to the type seed and root.

• 생명과학회지
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• 제17권3호통권83호
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• pp.407-411
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• 2007

효소생산을 최적화하기 위해서 Paenibacillus sp. DG-22에서의 ${\beta}-xylosidase$ 생합성 조절을 연구하였다. Paenibacillus sp. DG-22의 ${\beta}-xylosidase$는 배양액에 존재하는 탄소원에 의해 조절되는 것으로 관찰되었다. ${\beta}-Xylosidase$의 합성은 xylan과 methyl ${\beta}-D-xylopyranoside$ (${\beta}MeXyl$)에 의해 유도되었으나 쉽게 대사되는 단당류에 의해서는 약간 억제되었다. ${\beta}MeXyl$가 ${\beta}-xylosidase$의 유도를 위한 최적의 기질임을 확인하였고 가장 효과적인 유도는 10 mg/ml의 농도에서 얻어졌다. ${\beta}-Xylosidase$의 생산은 세포의 생장과 연관된 양상을 나타내었으며, 대수기 말에 최대양이 형성되었다. Glucose와 xylose가 존재하면 ${\beta}-xylosidase$의 활성 수준이 감소하는 것으로 보아 이 효소의 생합성은 catabolite repression을 받는것으로 보인다. SDS-PAGE와 활성염색 기술을 이용하여 ${\beta}Mexyl$가 이 효소의 생합성을 유도하며 약 80 kDa 크기의 하나의 ${\beta}-xylosidase$가 존재함을 알 수 있었다.