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허완수 崇實大學校 生産技術硏究所 1996 論文集 Vol.26 No.2
Synthetic marbles have been developed due to the excellent heat resistance, chemical resistance, good processibility, and uncomparable toughness for many years. Thermoset resin such as unsaturated polyester or poly(methyl methacrylate) has been used and recently allyster resin which can be polymerized using dially monomer and polyol by transesterification reaction shows lot of interests. In this study, the reactivity and curing mechanism has been studied by differential scanning calorimetry followed by the selection of monomer, diol, and curing agent. Diallyl terephthalate and diallyl isophthalate were used as prepolymer and diethylene glycol and 1,3-butane diol were used as allyl monomer. Several curing agents such as dicummyl peroxide, t-butyl peroxybenzoate, t-butyl peroxy-2-ethyl hexanoate, 2-butanone peroxide, or di-t-butyl peroxide have been studied for the optimum curing process. Isothermal and dynamic differential scanning calorimetry(DSC) methods with varying heating rate were utilized and activation energy of 90.3kJ/mol for DCP and 86.6kJ/mol for TBPB were calculated by Kissinger equation. Besides, DCP and TBPB have been found to exhibit good curing results since over 100 C, the decomposition rate of curing agent was vary fast enough ti induce the brittle physical properties.
Wan Soo Kim,Jong Wook Kim,Jae Hak Lee,Sung Hoe Huh 한국해양과학기술원 2008 Ocean science journal Vol.43 No.2
Laboratory bioassays were conducted to test the acute toxicity effects of sudden exposure to sodium cyanide (NaCN) on the endogenous rhythm of the oxygen consumption rate (OCR) in the black rockfish Sebastes schlegeli. The OCR of the black rockfish (n = 14, total length = 20.4 ± 1.16 cm, wet weight = 158 ± 25 g) was measured with an automatic intermittent-flow-respirometer. OCR decreased significantly when experimental fish were exposed to NaCN. When exposed to 10 ppb NaCN, fish were able to recover their OCR rhythmic activities. When fish were exposed to 20 ppb, however, the metabolic activity rhythms were not recovered. These results suggest that exposure to NaCN concentrations over 20 ppb cause severe physiological damage to the endogenous rhythms of black rockfish.
Alteration of The Quaternary Structure of Human UDP-Glucose Dehydrogenase by a Double Mutation
Huh, Jae-Wan,Yang, Seung-Ju,Hwang, Eun-Young,Choi, Myung-Min,Lee, Hyun-Ju,Kim, Eun-A,Choi, Soo-Young,Choi, Jene,Hong, Hea-Nam,Cho, Sung-Woo Korean Society for Biochemistry and Molecular Biol 2007 Journal of biochemistry and molecular biology Vol.40 No.5
There are conflicting views for the polymerization process of human UDP-glucose dehydrogenase (UGDH) and no clear evidence has been reported yet. Based on crystal coordinates for Streptococcus pyogenes UGDH, we made double mutant A222Q/S233G. The double mutagenesis had no effects on expression, stability, and secondary structure. Interestingly, A222Q/S233G was a dimeric form and showed an UGDH activity, although it showed increased $K_m$ values for substrates. These results suggest that Ala222 and Ser233 play an important role in maintaining the hexameric structure and the reduced binding affinities for substrates are attributable to its altered subunit communication although quaternary structure may not be critical for catalysis.
Huh, Jung-Bo,Lee, Jeong-Yeol,Jeon, Young-Chan,Shin, Sang-Wan,Ahn, Jin-Soo,Ryu, Jae-Jun The Korean Academy of Prosthodonitics 2013 The Journal of Advanced Prosthodontics Vol.5 No.2
PURPOSE. The aim of this study was to evaluate the stability of arginine-glycine-aspartic acid (RGD) peptide coatings on implants by measuring the amount of peptide remaining after installation. MATERIALS AND METHODS. Fluorescent isothiocyanate (FITC)-fixed RGD peptide was coated onto anodized titanium implants (width 4 mm, length 10 mm) using a physical adsorption method (P) or a chemical grafting method (C). Solid Rigid Polyurethane Foam (SRPF) was classified as either hard bone (H) or soft bone (S) according to its density. Two pieces of artificial bone were fixed in a customized jig, and coated implants were installed at the center of the boundary between two pieces of artificial bone. The test groups were classified as: P-H, P-S, C-H, or C-S. After each installation, implants were removed from the SRPF, and the residual amounts and rates of RGD peptide in implants were measured by fluorescence spectrometry. The Kruskal-Wallis test was used for the statistical analysis (${\alpha}$=0.05). RESULTS. Peptide-coating was identified by fluorescence microscopy and XPS. Total coating amount was higher for physical adsorption than chemical grafting. The residual rate of peptide was significantly larger in the P-S group than in the other three groups (P<.05). CONCLUSION. The result of this study suggests that coating doses depend on coating method. Residual amounts of RGD peptide were greater for the physical adsorption method than the chemical grafting method.
白鼠에서 Morphine의 鎭痛效果와 그 耐性發現에 미치는 Vasopressin의 影響
허광열,한규송,김기원,채수완,조규박 의과학연구소 1991 全北醫大論文集 Vol.15 No.3
Morphine and its derivatives are still the most widely used drugs for the relief of pain in modrate to severe intensity. However, development of tolerance to many of their pharmacoligical actions, particularly to the analgesia has limited its value of use. Recentlt, there are mant evidenced that it suggests the close relationship between de velopment of tolerance. Therefore, in this stidt, the influence of arginine vasopressin and its major metavolite AVPOsvl in-the debelopment of tolerancr to the analgrsic rffect of thr drug were examined in the ret. AVP produced significant analgesia in the rat. But the AVP Meta bolite, could not induce ant changes in the respinse to thernal stimuli of the rat. This analgesic effect of AVP was not affected by nalaxone but severely diminished by V1 vasopressin recrptor antagonist, Both of thesepeptide and its metabolite did not influencd the analgesic effict of morphine. Significant tolerance to analgesic effect of morphine was induced by repeated injection of morphine at 3rd day from the beginning of the injection, This development of tolerance to analgesic effect of morphine was not affected by small dose of AVP but facilitated by fairly large dose of AVP in its timing of development and in degree of tolerance. Though the small dose of have no influence on the development of tolerance to analgesic effect of morphine, small dose of 1μg/kg of restored the analgesic effect of morphine to its potency of control value. These results indicate that AVP could produce a analgesic action that mediate not by opioid transmission but by vasopressin receptor, certainly V1. And also, it is suggested that vasopressin and its surrogates could greatly influence the development of tolerance to analgesic effect of morphine.