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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.
Effect of Electron Beam and ${\gamma}$-Ray Irradiation on the Curing of Epoxy Resin
Kang, Phil-Hyun,Park, Jong-Seok,Nho, Young-Chang The Polymer Society of Korea 2002 Macromolecular Research Vol.10 No.6
The effect of an electron beam and ${\gamma}$-ray irradiation on the curing of epoxy resins was investigated. Diglycidyl ether of bisphenol A (DGEBA) and diglycidyl ether of bisphenol F (DGEBF) as epoxy resin were used. The epoxy resins containing 1.0-3.() wt% of triarylsulphonium hexafluoroantimonate(TASHFA) and triarylsulphonium hexafluorophosphate(TASHFP) as initiator were irradiated under nitrogen at room temperature with different dosage of EB and ${\gamma}$-rays from a Co$^{60}$ u source. The chemical and mechanical characteristics of irradiated epoxy resins were compared after curing of EB and ${\gamma}$-ray irradiation. The thermal properties of cured epoxy were investigated using dynamic mechanical thermal analysis. The chemical structures of cured epoxy were characterized using near infrared spectroscopy. Mechanical properties such as flexural strength, modulus were measured. The gel fraction of DGEBA with ${\gamma}$-ray was higher than that of the epoxy with EB at the same dose. Young's modulus of the sample irradiated by ${\gamma}$-ray is higher than that of sample cured by EB. From the result of strain at yield, it was found that the epoxy cured by ${\gamma}$-ray had a higher stiff property compared with the irradiated by EB.
Phosphoproteomic analysis of neuronal cell death by glutamate-induced oxidative stress
Kang, Tae Hyuk,Bae, Kwang-Hee,Yu, Min-jung,Kim, Won-Kon,Hwang, Hyang-Ran,Jung, Hyeyun,Lee, Phil Young,Kang, Sunghyun,Yoon, Tae-Sung,Park, Sung Goo,Ryu, Seong Eon,Lee, Sang Chul WILEY-VCH Verlag 2007 Proteomics Vol.7 No.15
<P>Oxidative stress is one of the major causes of neuronal cell death in disorders such as perinatal hypoxia and ischemia. Protein phosphorylation is the most significant PTM of proteins and plays an important role in stress-induced signal transduction. Thus, the analysis of alternative protein phosphorylation states which occur during oxidative stress-induced cell death could provide valuable information regarding cell death. In this study, a reference phosphoproteome map of the mouse hippocampal cell line HT22 was constructed based on 125 spots that were identified by MALDI-TOF or LC-ESI-Q-TOF-MS analysis. In addition, proteins of HT22 cells at various stages of oxidative stress-induced cell death were separated by 2-DE and alterations in phosphoproteins were detected by Pro-Q Diamond staining. A total of 17 spots showing significant quantitative changes and seven newly appearing spots were identified after glutamate treatment. Splicing factor 2, peroxiredoxin 2, S100 calcium binding protein A11, and purine nucleoside phosphorylase were identified as up- or down-regulated proteins. CDC25A, caspase-8, and cyp51 protein appeared during oxidative stress-induced cell death. The data in this study from phosphoproteomic analysis provide a valuable resource for the understanding of HT22 cell death mechanisms mediated by oxidative stress.</P>
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.
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.
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>
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>