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PREPARATION OF SiC/C COMPOSITE SHEET FROM POLYCARBOSILANE/CARBON : BASED RESIN MIXTURE
Kang, Phil Hyun,Yang, Hyun Soo 한국화학공학회 1998 Korean Journal of Chemical Engineering Vol.15 No.6
SiC/C composites were prepared from a mixture of polycarbosilane and phenolic resin with weight ratio of 2/1 and 1/1 using PVB as a binder. The two types of green bodies which were formed by mould pressing method were treated in the temperature range from 1,000℃ to 1,500℃ under nitrogen. X-ray diffraction patterns, density, flexural strength and fracture surfaces of the composite were examined. The flexural strength of the composites at room temperature increased with heat-treatment temperature and showed a maximum value of 175 MPa at 1,300℃. When the composite was heat treated at 1,400℃, the flexural strength decreased rapidly due to the crystallization of SiC. The SiC/C composites showed good oxidation resistance up to 830℃. The effective mixing ratio of PCS/phenolic resin to obtain improved mechanical property was 2/1.
Glycine decarboxylase regulates the maintenance and induction of pluripotency via metabolic control
Kang, Phil Jun,Zheng, Jie,Lee, Gilju,Son, Daryeon,Kim, In Yong,Song, Gwonhwa,Park, Gyuman,You, Seungkwon Academic Press 2019 Metabolic engineering Vol.53 No.-
<P><B>Abstract</B></P> <P>Reprogramming of ‘adult’ differentiated somatic cells to ‘embryonic’ pluripotent stem cells accompanied by increased rate of glycolysis. Conversely, glycolysis triggers accumulation of advanced glycation end products (AGEs), a potential causative factor in aging, by promoting methylglyoxal production. Therefore, it is reasonable that pluripotent stem cells (PSCs) would specifically regulate glycolysis to maintain their embryonic features. In this study, we focused on glycine decarboxylase (GLDC), a key enzyme in the glycine cleavage system that regulates glycolysis and methylglyoxal production in cancer. GLDC was exclusively expressed in PSCs, and inhibition of this enzyme induced alterations of metabolome and AGE accumulation, thereby suppressing the embryonic pluripotent state. Surprisingly, the level of accumulated AGEs in somatic cells gradually decreased during reprogramming, ultimately disappearing in iPSCs. In addition, ectopic expression of GLDC or treatment with the AGE inhibitor LR-90 promoted reprogramming. Together, these findings suggest that GLDC-mediated regulation of glycolysis and controlling AGE accumulation is related to maintenance and induction of pluripotency.</P> <P><B>Highlights</B></P> <P> <UL> <LI> GLDC is a metabolic regulator in human PSCs. </LI> <LI> GLDC-mediated regulation of glycolysis is involved in controlling AGE accumulation. </LI> <LI> AGE depletion is related to maintenance and induction of pluripotency. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Interactome Analysis of Yeast Glutathione Peroxidase3
( Phil Young Lee ),( Kwang Hee Bae ),( Chang Won Kho ),( Sung Hyun Kang ),( Do Hee Lee ),( Sa Yeon Cho ),( Seong Man Kang ),( Sang Chul Lee ),( Byoung Chul Park ),( Sung Goo Park ) 한국미생물 · 생명공학회 2008 Journal of microbiology and biotechnology Vol.18 No.8
Characteristics of Heat Shrinkable High Density Polyethylene Crosslinked by ${\gamma}$-Irradiation
Kang, Phil-Hyun,Nho, Young-Chang Korean Nuclear Society 2001 Nuclear Engineering and Technology Vol.33 No.2
The effects of ${\gamma}$-irradiation on the crosslinking of high density polyethylene (HDPE) was investigated for the purpose of obtaining a suitable formulation for heat shrinkable materials. In this study the HDPE specimens were prepared by blending with cross linking agents and pressed into a 0.2 mm sheet at 18$0^{\circ}C$. ${\gamma}$-irradiation was conducted at 40 to 100 kGy in nitrogen. The heat shrinkable property and thermal mechanical property of the HDPE sheets have been investigated. It was found that the degree of crosslinking of the irradiated HDPE samples were increased with irradiation dose. Compared with the HDPE containing triallylisocyanurate, the HDPE containing trimethylol propane triacrylate shows a slight increase in crosslinking density. The heat transformation and dimension change of HDPE decreased with increasing radiation dose. The heat shrinkage of the samples increased with increasing annealing temperatures. The thermal resistance of HDPE increased upon the crosslinking of HDPE.
Effect of electron beam irradiation on polyimide film
Phil-Hyun Kang,Young-Kyou Jeon,Joon-Pyo Jeun,Jin-Wook Shin,Young-Chang Nho 한국공업화학회 2008 Journal of Industrial and Engineering Chemistry Vol.14 No.5
The effects of electron beam radiation on polyimide films were investigated through dynamic mechanical analysis (DMA), in which the energy of the electron beam was set to a voltage of 1 MeVand a beam current of 4 mA. The b2 sub-glass relaxation temperature of polyimide decreased with irradiation dose, consisting with formation of free radicals at the ends of the molecular chains. The glass relaxation temperatures are not influenced as a function of increasing electron beam exposure because imide rings prevent structural damage by electron beam irradiation. Furthermore, decomposition temperatures of the irradiated polyimide slightly decrease, from 571.42 to 570.67 8C and the residue weight also decreases.
Kang, Kai,Kang, Phil Hyun,Nho, Young Chang Wiley Subscription Services, Inc., A Wiley Company 2006 Journal of applied polymer science Vol.99 No.4
<P>Radiation-induced simultaneous grafting of styrene onto polytetrafluoroethylene (PTFE) films and the subsequent sulfonation in the chlorosulfonic acid/dichloroethane were investigated. The effects of the main radiation grafting conditions, such as the type of solvents, irradiation dose, dose rate, the styrene concentrations, etc., on the degree of grafting (DOG) were studied. To elucidate the influence of both the grafting and sulfonation conditions on the properties of the PTFE-g-polystyrene-sulfonic acid (PSSA) membranes, the sulfonation conditions, including the sulfonation temperature and the concentration of the ClSO<SUB>3</SUB>H with respect to the DOG, were systematically evaluated. The grafted and sulfonated membranes were characterized by FTIR–ATR spectra, ion-exchange capacity (IEC), water uptake, thickness measurement, etc. The as-prepared PTFE-g-PSSA membranes in this work showed a good combination of a high IEC (0.85–2.75 meq g<SUP>−1</SUP>), acceptable water uptake (8.86–56.9 wt %), low thickness, and volume expansion and/or contraction. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1415–1428, 2006</P>