• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.1031-1034
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• 2007

The R- and Z-substituent effects for the gas-phase thermal decompositions of carbamates, R2NC(=O)- OCH2CH2Z, have been investigated theoretically at B3LYP level with 6-31G(d) and 6-31++G(d,p) basis sets. Both the Z- and R-substituent effects on reactivity (ΔH≠) were well consistent with experimental results, although the R-substituent effect was underestimated theoretically. No correlations were found between activation enthalpies and reaction enthalpies. The substituent effects on reactivity seemed to be complicated at a glance, but were understandable by concurrent electronic and steric factors. Variations of bond lengths at TS structures were well correlated with the Taft's σ* values and the TS structures became tighter as the Zsubstituent became a stronger electron-acceptor (δσ* > 0). However the effects of R-substituents on the TS structures were much smaller when compared to those of Z-substituents.

• Asian-Australasian Journal of Animal Sciences
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• 제7권3호
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• pp.421-426
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• 1994

Twelve cross bred cows ($300{\pm}20kg$) were fed a basal ration consisting of 1 kg concentrate and untreated or urea treated rice with or without urea-molasses-wheat bran lick block supplementation. The lick blocks were prepared locally using cement as a binding agent. The experiment lasted for 48 days consisting of a preliminary period of 14 days and a measurement period of 34 days. Daily dry ma tter intake (DMI) of straw and lick block, and daily milk yield were recorded during the measurement period. Intake of lick block when fed with untreated straw (US) was significantly higher (p < 0.01) than with urea treated (TS) straw (397 vs 307g $100kg^{-1}$), but lick block supplementation did not significantly affect the in take of US (1.80 vs 1.83kg $100kg^{-1}day^{-1}$) or TS (2.27 vs 2.17kg $100kg^{-1}day^{-1}$). Both urea treatment and lick block supplementation significantly increased (p < 0.01) the milk yield of cows, and the increase due to urea treatment was higher than that due to lick block supplementation. Benefit/cost ratio obtained for feeding US or TS with 1 kg dairy concentrate was similar (5.4), but the marginal return favours TS (5.4:1.0). The benefit/cost ratio for US and TS supplemented with lick block was 3.4 and 3.7. respectively, but the marginal return with US was higher than with TS (1.6:1.0 and 0.9:1.0, respectively).

• Toxicological Research
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• 제28권4호
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• pp.241-248
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• 2012

Exposure of cells to ultraviolet B (UVB) radiation can induce production of free radicals and reactive oxygen species (ROS), which damage cellular components. In addition, these agents can stimulate the expression of matrix metalloproteinase (MMP) and decrease collagen synthesis in human skin cells. In this study, we examined the anti-photoaging effects of extracts of Tetraselmis suecica (W-TS). W-TS showed the strongest scavenging activity against 2,2-difenyl-1-picrylhydrazyl (DPPH) and peroxyl radicals, followed by superoxide anions from the xanthine/xanthine oxidase system. We observed that the levels of both intracellular ROS and lipid peroxidation significantly increased in UVB-irradiated human skin fibroblast cells. Furthermore, the activities of enzymatic antioxidants (e.g., superoxide dismutase) and the levels of non-enzymatic antioxidants (e.g., glutathione) significantly decreased in cells. However, W-TS pretreatment, at the maximum tested concentration, significantly decreased intracellular ROS and malondialdehyde (MDA) levels, and increased superoxide dismutase and glutathione levels in the cells. At this same concentration, W-TS did not show cytotoxicity. Type 1 procollagen and MMP-1 released were quantified using RT-PCR techniques. The results showed that W-TS protected type 1 procollagen against UVB-induced depletion in fibroblast cells in a dose-dependent manner via inhibition of UVB-induced MMP-1. Taken together, the results of the study suggest that W-TS effectively inhibits UVB-induced photoaging in skin fibroblasts by its strong anti-oxidant ability.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.175-175
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• 2000

Si(100) surfaces were exposed to gas-phase thermal-energy hydrogen atoms, H(g). We find that thermal H(g) atoms etch, amorphize, or penetrate into the crystalline silicon substrate, depending on the employed Ts range during the H(g) exposure. We find that etching is enhanced as Ts is lowered in the 300-700K range, while amorphous silicon hydride (a-Si:H) formation dominates at a Ts below 300K. This result was well explained by the fact that formation of the etching precursor, SiHx(a), and amorphization are both facilitated by a lower Ts, whereas the final step for etching, SiH3(a) + H(g) longrightarrow SiH3(g), is suppressed at a lower Ts. we also find that direct absorption of H(g) by the crystalline bulk of Si(100) substrate occurs within a narrow Ts window of 420-530K. The bulk-absorbed hydrogen evolved out molecularly from Si(100) at a Ts 80-120K higher than that for surface monohydride phase ($\beta$1) in temperature-programmed desorption. This bulk-phase H uptake increased with increasing H(g) exposure without saturation within our experimental limits. Direct absorption of H(g) into the bulk lattice occurs only when the surface is atomically roughened by surface etching. While pre-adsorbed hydrogen atoms on the surface, H(a), were readily abstracted and replaced by D(g), the H atoms previously absorbed in the crystalline bulk were also nearly all depleted, albeit at a much lower rate, by a subsequent D(g) at the peak temperature in TPD from the substrate sequentially treated with H(g) and D(g), together with a gas phase-like H2 Raman frequency of 4160cm-1, will be presented.

• 미생물학회지
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• 제35권4호
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• pp.258-265
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• 1999

출아효모에서는 질소원의 고갈과 MATa/MAT${\alpha}$ 이배체 세포의 감수분열기 특이적인 유전자 발현에 의해 체세포분열기의 G1기에서 감수분열기로의 진행이 결정된다. 이러한 두 경로는 감수분열기 특이적인 IME 유전자군에 의한 전사조절에 의해 활성화되어 감수분열기가 시작된다. 본 연구는 IME2 유전자가 protein kinase 로서 감수분열기의 어떤 과정에 직접 관여하는가를 조사하기 위하여 먼저 PCR mutagenesis를 통하여 온도감수성 ime2 변이주를 분리하였다. 전체 62개의 온도감수성 변이주 중에서 온도에 따른 포자형성능과 감수분열기 재조합 빈도에 대하여 명확한 차이를 나타내는 3종류의 변이주들(ts ${\cdot}$ ime2-11, ts ${\cdot}$ ime2-12와 ts ${\cdot}$ ime2-13)을 선택하였다. 이러한 3종류의 온도감수성 변이주를 이용하여 제한온도에서 감수분열기 초기과정 중 결손을 조사하기 위해, FACScan analysis를 한 결과 IME2유전자가 감수분열기의 DNA 복제과정의 개시 및 완료에 관여함을 알 수 있었고, his4 혹은 arg4 locus에서 감수분열기 재조함 빈도의 측정으로 재조합 과정에 중요한 역할을 한다는 것을 알 수 있었다. 더욱이${\Delta}$mre4 파괴주에 IME2유전자를 과다발현시켜 그 영향을 조사한 결과, 감수분열기 특이적인 protein kinase 인 IME2와 MRE4가 감수분열기 초기과정인 재조합 과정에서는 동일한 경로에 작용한다는 것이 제시되었다.

• 한국미생물·생명공학회지
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• 제18권1호
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• pp.89-93
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• 1990

재조합 pBR322-trp$^+$ 플라스미드의 숙주내 안정적 유지를 목적으로 tRNA phe 의 구조유전자인 pheW$^+$ 유전자를 pBR322-trp$^+$의 플라스미드에 도입시키고, 숙주세포로는 트립토판 생산을 위한 정상숙주 LC901의 phenylalanyl tRNA synthetase 온도감수성 변이체인 LC901-pheS-ts를 구성하여 이 온도감수성 숙주의 제한온도 (restrictive temperature)에서 재조합 trp$^+$ 플라스미드의 안정적 유지와 trp$^+$ 유전자가 미치는 효과를 조사하였다.

• Journal of Korean Vacuum Science & Technology
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• 제2권2호
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• pp.107-117
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• 1998

Epitaxial undoped and Sb-doped si films have been grown on Si(001) substrates at temperatures T between 80 and 750$^{\circ}C$ using energetic Si in ultra-high-vacuum Kr+-ion-beam sputter deposition(IBSD). Critical epitaxial thicknesses te, The average thickness of epitaxial layers, in undoped films were found to range from 8nm at Ts=80$^{\circ}C$ to > 1.2 ${\mu}$m at Ts=300$^{\circ}C$ while Sb incorporation probabilities $\sigma$sb varied from unity at Ts 550$^{\circ}C$ to 0.1 at 750$^{\circ}C$. These te and $\sigma$Sb values are approximately one and one-to-three orders of magnitude, respectively, higher than reported results achieved with molecular-beam epitaxy. Plan-view and cross-sectional transmission electron microscopy, high-resolution x-ray diffraction, channeling and axial angular-yield profiles by Rutherford back scattering spectroscopy for epitaxial Si1-x Gex(001) alloy films (0.15$\leq$x$\leq$0.30) demonstrated that the films are of extremely high crystalline quality. critical layer thicknesses hc the film thickness where strain relaxation starts, I these alloys wre found to increase rapidly with decreasing growth temperature. For Si0.70 Ge0.30, hc ranged from 35nm at Ts=550$^{\circ}C$ to 650nm at 350$^{\circ}C$ compared to an equilibrium value of 8nm.

• 한국축산식품학회지
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• 제34권5호
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• pp.604-613
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• 2014

This study was carried out to evaluate the effects of various kinds of salt on the quality and storage characteristics of tteokgalbi. The tteokgalbi was prepared using four types of salt: 1.5% purified salt (control, C), 1.5% five-year-old solar salt (FS), 1.5% Topan solar salt (TS), and 1.5% French Gu$\acute{e}$rande solar salt (GS). The moisture, crude lipid, crude ash, crude protein and calorie contents, water holding capacity, and cooking loss were not significantly different between control and all other treatments. As for the textural characteristics, the use of GS increased the hardness of the tteokgalbi. According to the sensory evaluation, the use of TS had the best score in springiness. Tteokgalbi made with TS and GS had the two highest scores in flavor and total acceptability. During 15 d of storage, the contents of 2-thiobarbituric acid (TBA) value, volatile basic nitrogen (VBN) and the total microbial counts increased, while the pH decreased. The TBA values of the tteokgalbi containing TS and GS were lower than that of C. Lightness (L) and yellowness (b) values decreased during storage, but redness (a) displayed no significant difference during storage. Overall, the best results, in terms of TBA value and sensory attributes, were obtained for the tteokgalbi containing TS and GS.

• 상하수도학회지
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• 제18권1호
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• pp.59-65
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• 2004

The change of the microbial community structure in excess sludge of different sewage treatment plants by ozone treatment was investigated by quinone profiles. The resulting ozone dosage ranged from 0.1 to $0.4gO_3/gTS$. In terms of overall sludge reduction, more than 50% reduction of the total sludge mass could be achieved by ozone treatment at $0.4gO_3/gTS$. Quinone concentration and type in sludge of different treatment plants were remarkably decreases with increasing ozone dose. Ubiquinones(UQs)-8, -10 and MK-8 were still remained in the ozonized sludge at $0.4gO_3/gTS$. The results of this study showed that the remaining microorganisms belong to UQs-8, -10 and MK-8 were difficult to destruct cell membrane or wall by ozonation. Fecal Streptococci and Salmonella were not detected at ozone dose of $0.2gO_3/gTS$, but Fecal Coliform was not detected at ozone dose of $0.4gO_3/gTS$.

• Biomolecules & Therapeutics
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• 제7권2호
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• pp.138-144
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• 1999

Recent studies have suggested that Panax ginseng saponins may stimulate pancreaticobiliary secretion. However, the precise mechanisms underlying the alterations in pancreaticobiliary function associated with ginseng saponins remain uncertain. We studied the effects of ginseng saponins and devazepide, cholecys-tokinin receptor antagonist, on pancreaticobiliary secretion in male Sprague-Dawley rats. The saponins tested were crude saponin (TS) and panaxatriol saponin (PTS). After single or two weeks administration of saponins, pancreaticobiliary juice of rats was collected for 8hrs. Single administration of TS and PTS did not change the volume of pancreaticobiliary juice compared with control group. In contrast, the pretreatment of devazepide significantly increased the volume of pancreaticobiliary juice. The amylase activity was significantly increased by acute TS treatment, but this increase was inhibited by devazepide pretreatment. In animals with two weeks administration of TS and PTS, the volume of pancreaticobiliary juice was not increased as compared to the control group. However, the volume of pancreaticobiliary juice was significantly increased by devazepide treatment. The amylase activity was significantly increased by two weeks administration TS and PTS respectively. This increase was inhibited by devazepide treatment. Our findings suggest that ginseng saponins, especially panaxatriol, increase the amylase activity in pancreaticobiliary juice, and this is, in part, caused by release of endogenous cholecystokinin.