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Effect of Highly Pressurized Hydrogen Gas Charging on the Hydrogen Embrittlement of API X70 Steel
Dong-Su Bae,Chi-Eun Sung1,Hyun-Ju Bang,Sang-Pill Lee,Jin-Kyung Lee,In-Soo Son,조영래,Un-Bong Baek,Seung-HoonNahm 대한금속·재료학회 2014 METALS AND MATERIALS International Vol.20 No.4
During the use of API X70 steel as a pipeline structural material for the transportation of natural gas,hydrogen embrittlement can occur due to the hydrogen contained in natural gas. The aim of this study is toinvestigate the effects of the hydrogen content under high-pressure hydrogen gas conditions on the hydrogenembrittlement of air-cooled API X70 steel. The air-cooled API X70 steel was manufactured by hot rollingand was then air-cooled to room temperature. Tensile test specimens were held for 0 h, 1000 h, and 2000 hwithin a pressure vessel filled with 100% hydrogen gas at a gas pressure of 10 MPa, with the tensile teststhen performed at room temperature. The microstructure of the API X70 steel consists of coarse polygonalferrite, coarse pearlite, and fine acicular ferrite. The yield and tensile strength increased and elongationdecreased considerably after a holding time of 2000 h compared to those of 0 h and 1000 h within the pressurevessel. The morphology of the fracture surface changed from ductile to brittle upon hydrogen gas charging. Secondary cracks were observed in both of the hydrogen-gas-charged specimens. No external cracks wereformed on the surface of the tensile-tested specimen with a 0 h holding time; however, many external crackswere observed on the specimen surface subjected to hydrogen gas charging.
Lee, Seungyeol,Baek, Seungmin,Park, Joong Pill,Park, Ju Hyun,Hwang, Dae Yeon,Kwak, Sang Kyu,Kim, Sang-Wook American Chemical Society 2016 Chemistry of materials Vol.28 No.10
<P>Cationic-exchange methods allow for the fabrication of metastable phases or shapes, which are impossible to obtain with conventional synthetic colloidal methods. Here, we present the systematic fabrication of heteronanostructured (HNS) Cu2-xS@CuInS2 nanodisks via a cationic-exchange reaction between Cu and In atoms. The indium trioctylphosphine complex favorably attacks the lateral (16 0 0) plane of the roxbyite Cu2-xS hexagon. We explain the phenomena by estimating the formation energy of vacancies and the heat of reaction required to exchange three Cu atoms with an In atom via density functional theory calculations. In an experiment, a decrease in the amount of trioctylphosphine surfactant slows the reaction rate and allows for the formation of a lateral heterojunction structure of nanoplatelets. We analyze the exact structures of these materials using scanning transmission electron microscopy-energy dispersive X-ray spectroscopy and high-resolution transmission electron microscopy. Moreover, we demonstrate that our heteronanodisk can be an intermediate for different HNS materials; for example, adding gold precursors to a Cu2-xS@CuInS2 nanodisk results in a AuS@CuInS2 nanodisk via an additional cationic reaction between Cu ions and Au ions.</P>
Impact Fracture Characteristics on Fabricating Process of $Nb/MoSi_2$ Laminate Composite (I)
Lee, Sang-Pill,Yoon, Han-Ki The Korean Society of Mechanical Engineers 2000 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.14 No.8
[ $Nb/MoSi_2$ ]laminate composites have been successfully fabricated by hot pressing in a graphite mould. Lamination of Nb foil and $MoSi_2$ layer showed a sufficient improvement in the absorbed impact energy compared to that of monolithic $MoSi_2$ material. The impact value of $Nb/MoSi_2$ laminate composites obviously is reduced when sintered at temperatures higher than 1523K, even if the composite density contributing to impact load increased along with fabricating temperatures. Impact value of laminate composites was also drastically decreased with the growth of reaction layer after the heat treatment. However, it was effective to increase the pressure at the same sintering temperature for the improvement of the impact value.
Lee, Kwang-Pill,Choi, Seong-Ho,Park, Yu-Chul,Bae, Zun-Ung,Lee, Mu-Sang,Lee, Sang-Hak,Chang, Hye-Yong,Kwon, Se-Mok,Kazuhiko Tanaka Korean Chemical Society 2003 Bulletin of the Korean Chemical Society Vol.24 No.9
The simultaneous determination of anions ($SO_4 ^{2-},\;Cl^-,\;and\;NO_3^-$) and cations ($Na^+,\;NH^{4+},\;K^+,\;Mg^{2+},\;and\;Ca^{2+}$) in natural water obtained by Nakdong River waters system in Korea were performed by ion-exclusion/cationexchange chromatography with conductimetric detection. The stationary phase was a polymethacrylate-based weakly acidic cation-exchange resin column in the $H^+$-form and a weak-acid eluent. When using only a 1.4 mM sulfosalicylic acid/6 mM 18-crown-6 ether as an eluent, good resolution of both anions and cations, minimum time required for the separation, and satisfactory detection sensitivity were obtained in a reasonable time. The method was successfully applied to the simultaneous determination of anions and cations in natural waters.
The Study of Doxorubicin and its Complex with DNA by SERS and UV-resonance Raman Spectroscopy
Lee, Chul-Jae,Kang, Jae-Soo,Kim, Mak-Soon,Lee, Kwang-Pill,Lee, Mu-Sang Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.8
The interaction of the antitumour agent doxorubicin with calf thymus DNA is investigated in an aqueous solution at a pH level of 6-7 with molar ratios of 1/10. A UV-resonance Raman spectroscopy and surface enhanced Raman spectroscopy are used to determine the doxorubicin binding sites and the structural variations of doxorubicin-DNA complexes in an aqueous solution. Doxorubicin intercalates with adenine and guanine via a hydrogen bond formation between the N7 positions of purine bases and the hydroxyl group of doxorubicin.
Pioglitazone Improves Oocyte Maturation and Subsequent Developmental Competence of Porcine Embryos
Sang-Gi Jeong,Seung-Eun Lee,Won-Jae Kim,Jae-Wook Yoon,Chan-Oh Park,Hyo-Jin Park,Dong-Yong Hong,Eun-Young Kim,Se-Pill Park 한국동물생명공학회(구 한국동물번식학회) 2018 발생공학 국제심포지엄 및 학술대회 Vol.2018 No.06
The optimization of culture condition is both basic and important for improving oocyte maturation, subsequent development of preimplantation embryo, and further implantation. This study performed to confirm effect of pioglitazone (PIO) treatment directly on porcine oocyte during in vitro maturation, further development of embryo. Immature oocytes were cultured in IVM medium, containing 0, 0.01, 0.1, 1, and 10 μM pioglitazone (0, 0.01, 0.1, 1, and 10 PIO, respectively) for 44 h. Although both oocyte survival and polar body emission did not significantly differ between the control and PIO-treated groups, percentage of normal spindle formation and chromosome alignment was increased in the 1 PIO-treated group than in the control group (control, 60.9±8.2%; and 1 PIO, 81.5±5.9%, p<0.1). Level of GSH was significantly increased in 1 PIO-treated group than in the control group (control, 100.0±5.0%; and 1 PIO, 119.8±5.2%, p<0.05), while the level of ROS was not differ in all groups. The rate of blastocyst was significantly higher in the 1 PIO-treated group than in the control at day 6 (control, 29.6±2.5%; and 1 PIO, 37.9±2.3%, p<0.05) and 7 (control, 35.1±1.6%; and 1 PIO, 41.8±2.7%, p<0.05), respectively. These results indicated that PIO treatment during IVM showing beneficial effects on oocyte and embryonic development. Pioglitazone will contribute to enhancing efficiency of in vitro production.
Allicin Treatment Enhances the Developmental Potential of Porcine Oocytes during IVM
Sang-Gi Jeong,Seung-Eun Lee,Yun-Gwi Park,Yeo-Jin Son,Min-Young Shin,Eun-Young Kim,Se-Pill Park 한국수정란이식학회 2016 한국수정란이식학회 학술대회 Vol.2016 No.10
Allicin (AL) regulates the cellular redox, proliferation, viability, and cell cycle of different cells against extracellular-derived stress. This study was to investigate the effect of allicin treatment during in vitro maturation (IVM) on porcine oocyte maturation and developmental competence. Porcine follicular oocytes were cultured in 0 (control), 0.01, 0.1, 1, 10, and 100 μM AL added IVM media. The rate of polar body emission was higher in the 0.1 μM AL-treated group (74.5% ± 2.3%) than in the control (68.0% ± 2.6%). After parthenogenetic activation, the rates of cleavage and blastocyst formation were significantly higher in the 0.1 μM AL-treated group than in the control (p < 0.05). The reactive oxygen species level at metaphase II was not significantly different among all groups. In matured oocytes, the relative mRNA expression of both BAK and CASP3, and BIRC5 were significantly lower and higher, respectively, in the 0.1 AL-treated group than in the control. Also, the mRNA expression of BMP15 and cyclin B, and the activity of phospho-p44/42 MAPK, was significantly increased. These results indicate that supplementation of oocyte maturation medium with allicin during IVM improves the maturation of oocytes and the subsequent developmental competence of porcine oocytes.