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졸-겔법으로 제조한 ZrO_2·SiO_2계 결정화 유리의 결정화 및 파괴인성에 관한 연구
신대용,한상목,강위수 강원대학교 산업기술연구소 2000 産業技術硏究 Vol.20 No.A
Precursor gels with the composition of xZrO_2·(100-x)SiO_2 systems (x=10,20 and 30mol%) were prepared by the sol-gel method. Kinetic parameter, such as activation energy, Avrami's exponent, n, and dimensionality crystal growth value, m, have been simultaneously calculated from the DTA data using Kissinger and Matusita equations. The crystallite size dependence on tetragonal to monoclinic transformation of ZrO_2 was investigated using XRD, in relation to the fracture toughness. The crystallization of tetragonal ZrO_2 occurred through 3-dimensional diffusion controlled growth(n=m=2) and the activation energy for crystallization was calculated using Kissinger and Matusita equations, as about 310∼325±10kJ/mol. The growth of t-ZrO_2, in proportion to the cube of radius, increased with increasing heating temperature and heat-treatment time. It was suggested that the diffusion of Zr4+ions by Ostwald ripening was rate-limiting process for the growth of t-ZrO_2 crystallite size. The fracture toughness of xZrO_2·(100-x)SiO_2 systems glass ceramics increased with increasing crystallite size of t-ZrO_2. The fracture toughness of 30ZrO_2·70SiO_2 system glass ceramics heated at 1,100℃ for 5h was 4.84 MPam^1/2 at a critical crystaliite size of 40 nm.
박지은,정연재,박준범,김혜영,유영현,이광식,양원태,김도훈,김종민 한국발생생물학회 2019 발생과 생식 Vol.23 No.3
Type 2 diabetes mellitus (T2DM) is characterized by insulin resistance (IR). T2DM is correlated with obesity and most T2DM medications have been developed for enhancing insulin sensitivity. Silk protein fibroin (SPF) from spiders has been suggested as an attractive biomaterial for medical purposes. We generated transgenic rice (TR) expressing SPF and fed it to diabetic BKS.Cg-m+/+Leprdb mice to monitor the changes in blood glucose levels and adipose tissue proteins associated with energy metabolism and insulin signaling. In the present study, the adipocyte size in abdominal fat in TR-SPF-fed mice was remarkably smaller than that of the control. Whereas the adenosine monophosphate-activated protein kinase (AMPK)-activated protein kinase and insulin receptor substrate 1 (IRS1) protein levels were increased in abdominal adipose tissues after TR-SPF feeding, levels of six-transmembrane protein of prostate 2 (STAMP2) proteins decreased. Phosphorylation of AMPK at threonine 172 and IRS1 at serine 307 and tyrosine 632 were both increased in adipose tissues from TR-SPFfed mice. Increased expression and phosphorylation of IRS1 at both serine 307 and tyrosine 632 in adipose tissues indicated that adipocytes obtained from abdominal fat in TR-SPF-fed mice were more susceptible to insulin signaling than that of the control. STAMP2 protein levels decreased in adipose tissues from TR-SPF-fed mice, indicating that STAMP2 proteins were reducing adipocytes that were undergoing lipolysis. Taken together, this study showed that TR-SPF was effective in reducing blood glucose levels in diabetic mice and that concurrent lipolysis in abdominal adipocytes was associated with alterations of AMPK, IRS1, and STAMP2. Increased IRS1 expression and its phosphorylation by TR-SFP were considered to be particularly important in the induction of lipolysis in adipocytes, as well as in reducing blood glucose levels in this animal model.
Wie-Chang Jin,Gweon-Young Ryu,Chun Yoon,Shin Jung Hyu Korean Chemical Society 1989 Bulletin of the Korean Chemical Society Vol.10 No.6
The$^{13}C$ NMR shifts of a series of para-substituted 9-aryl-tricyclo$[3.3.1.0^{2,8}]$non-9-yl and 8-aryl-tetracyclo$[3.2.1.0^{2,7}.0^{4,6}]$-oct-8-yl cations were measured in $FSO_3H/SO_2ClF \;at\; -90^{\circ}C\; or\; -70^{\circ}C$ in order to examine whether the ${\rho}^{c+}$ values can be used to explain the mechanism for the stabilization of the geometrically rigid cyclopropylcarbinyl cations. Plots of the ${\Delta}{\delta}^{c+}$ shifts against ${\sigma}^{c+}$ reveal excellent linear correlation. The tricyclononyl systems yield a ${\rho}^{c+}$ value of -4.95 with a correlation coefficient r = 0.9948. The tetracyclo-octanyl systems give a ${\rho}^{c+}$ value of -6.39 with r = 0.9943. A fair parallelism exists between the results of $^{19}F$ nmr studies and the change of ${\rho}^{c+}$ values in these cations. Accordingly, the present study established that the ${\rho}^{c+}$ value can be used as a mearsure of the geometric influence for the charge delocalization in cyclopropylcarbinyl cations.
Wie Sung Hwan Military Operations Research Society of Korea 1984 한국국방경영분석학회지 Vol.10 No.2
Consider an m machine flow shop with blocking. The processing time of job j,j=1,..., n on each one of the m machines is equal to the same random variable $X_j$ and is distributed according to $F_i$. We assume that the processing times are stochastically ordered, i.e., $F_{1_{-st}}{<}F_{2_{st}}{<}cdots_{-st}{<}F_n$. We show that the sequence 1,3,5,...,n-1,n,n-2,...,6,4,2 when n is even and sequence 1,3,5,...,n-2,n,n-1 ... 6,4,2 when n is odd minimizes the expected makespan and that the sequence 1,...,n minimizes the expected flow time.
Wie, J.,Jeong, S.,Kwak, M.,Myeong, J.,Chae, M.,Park, J. K.,Lee, S. W.,So, I. Springer Science + Business Media 2017 Pfl ugers Arch Vol.469 No.5
<P>The transient receptor potential (TRP) protein superfamily consists of a diverse group of cation channels that bear structural similarities to the fruit fly Drosophila TRP. The TRP superfamily is distinct from other groups of ion channels in displaying a large diversity in ion selectivity, modes of activation, and physiological functions. Classical TRP (transient receptor potential canonical (TRPC)) channels are activated by stimulation of Gq-PLC-coupled receptors and modulated by phosphorylation. The cyclic guanosine monophosphate (cGMP)-PKG pathway is involved in the regulation of TRPC3 and TRPC6 channels. Phosphodiesterase (PDE) 5 inhibitor induced muscle relaxation in corporal smooth muscle cells and was used to treat erectile dysfunction by inhibiting cGMP degradation. Here, we report the functional relationship between TRPC4 and cGMP. In human embryonic kidney (HEK) 293 cells overexpressing TRPC4, cGMP selectively activated TRPC4 channels and increased cytosolic calcium level through TRPC4 channel. We investigated phosphorylation sites in TRPC4 channels and identified S688 as an important phosphorylation site for the cGMP-PKG pathway. Cyclic GMP also activated TRPC4-like current with doubly rectifying current-voltage relationship in prostate smooth muscle cell lines. Taken together, these results show that TRPC4 is phosphorylated by the cGMP-PKG pathway and might be an important target for modulating prostate function by PDE5 inhibitors.</P>
Wie, G-A,Cho, Y-A,Kang, H-h,Ryu, K A,Yoo, M-K,Kim, J,Shin, S,Chun, O K,Joung, H Macmillan Publishers Limited, part of Springer Nat 2017 European journal of clinical nutrition Vol.71 No.10
<P>CONCLUSIONS: The traditional dietary pattern with high consumption of rice, kimchi, soybean paste and vegetables may decrease the cancer risk among Koreans, and strategies based on the dietary pattern may effectively reduce the cancer risk.</P>