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81.
Jungseok Heo Soo‐Young Kim Dongmok Whang Kimoon Kim 《Angewandte Chemie (International ed. in English)》1999,38(5):641-643
A honeycomb structure is shown by the one‐dimensional coordination polymer comprising D6h‐symmetric cucurbituril molecules and rubidium ions (see picture). The cucurbituril molecules stack atop one another and show coordination of their carbonyl groups to the rubidium ions in between. The shape and symmetry of the building blocks encourage the coordination polymer chains to be arranged in such a way as to produce an open‐framework structure with large, linear, hexagonal channels. 相似文献
82.
83.
Sun-Ae Moon Tae-Gu Lee Jin-Huek Hur Ki-Moo Heo Hoseon Yoo Seung-Jae Moon Jae-Heon Lee 《Heat and Mass Transfer》2008,44(11):1345-1353
In this paper, the averaged reentering rates of the densely built cooling towers, which form banks on the building roof in
Seoul, Korea have been predicted by a numerical method according to various summer wind conditions and roof wall types. The
averaged reentering rates of all the cooling towers are compared according to two wall types to study the effect of the intake
outdoor air louver on the reentering rates. Consequently, two findings are drawn as follows. (1) With a curtain wall, the
averaged reentering rates of the total cooling towers against the west and the south wind at ν = 5 m/s are 13.3 and 24.4%, respectively. Therefore, it is strongly needed to find a method to reduce the reentering of the
discharged air from the cooling towers. (2) In the case of a louver wall, the averaged reentering rates of the cooling towers
with the west and south wind at ν = 5 m/s are 2.5 and 9.74%, respectively, which have been estimated to be lower than those of the curtain wall. Therefore,
the louver wall can be suitably adopted to reduce the reentering of the discharged air from the cooling towers in the present
study. 相似文献
84.
Structural transformation of fluorinated carbon nanotubes induced by in situ electron-beam irradiation 总被引:1,自引:0,他引:1
An KH Park KA Heo JG Lee JY Jeon KK Lim SC Yang CW Lee YS Lee YH 《Journal of the American Chemical Society》2003,125(10):3057-3061
We have investigated the structural transformation of fluorinated singlewalled nanotubes (SWNTs) induced by electron-beam irradiation during the transmission electron microscope observations. Heavily fluorinated SWNT bundles were systematically transformed into multiwall-like nanotubes by releasing fluorine atoms during electron-beam irradiation and even broken into two pieces of the capped graphitic structures. Such structural transformations at relatively low kinetic energy (< or = 300 keV) could be explained by the local strains induced by fluorination, where C-C bonds that were fluorine-attached became 1.53 A, a single bond similar to that of a diamond, from our density functional calculations. We propose a possible concerted pathway for the structural transformation of fluorinated SWNTs induced by electron-beam irradiation based on the experimental observations. 相似文献
85.
B.S. Kang S. Kim F. Ren K. Ip Y.W. Heo B.P. Gila C.R. Abernathy D.P. Norton S.J. Pearton 《Applied Physics A: Materials Science & Processing》2005,80(2):259-261
Bulk Pt/ZnO Schottky rectifiers show gas sensitivities for CO of 4% and 8%, respectively, at 150 °C for 1 and 10% CO in N2. The current or voltage changes are time dependent, with an activation energy of 40.7 kJmol-1. Over a limited range of partial pressures of CO (PCO) in the ambient gas, the on-state resistance R of the sensor at fixed bias voltage decreased according to R=(RO+A(PCO)0.5)-1, where A is a constant and RO is the resistance in N2. Since these devices are also sensitive to H2 and C2H4, the ZnO rectifiers appear promising for a range of gas-sensing applications. PACS 81.05.Dz; 73.61.Ga; 72.80.Ey 相似文献
86.
87.
A photochromic phenoxyquinone based cyanide ion sensor 总被引:1,自引:0,他引:1
We have developed a new chemosensor system for cyanide ion that is based on a photochromic material. We observed that addition of cyanide anion to a UV irradiated solution of a phenoxynaphthacenequinone derivative brought about a significant change in the absorption spectra that enabled detection of cyanide ion in a selective and sensitive manner. A carbanion intermediate was shown to be responsible for the long wavelength absorption band (630-940 nm) that is generated by cyanide addition. 相似文献
88.
Tiefeng Xu Feifei Chen Shixun Dai Xiang Shen Xunsi Wang Qiuhua Nie Chao Liu Kai Xu Jong Heo 《Journal of Non》2011,357(11-13):2219-2222
Tellurite glasses from TeO2–Bi2O3–BaO pseudo-ternary system were prepared using a conventional melt-quenching method and its glass-forming region was determined. A series of glasses were selected and their third-order optical nonlinearities (TONL) were measured by employing the Z-scan method at a wavelength of 800 nm with femtosecond laser pulses. The results showed that glass former Te4+ ions exhibited positive influences on the TONL and glass modifiers Ba2+ ions behaved similarly; low concentrated Bi3+ ions as glass modifiers weakened the nonlinearities, but an excess amount of Bi3+ behaved oppositely. FTIR measurements demonstrated that chemical bonds especially Te–Oeq vibrated at a high energy level remarkably promoted the TONL susceptibility χ(3), and the glass sample with the highest Bi2O3 content exhibited the largest χ(3) value which was due to the presence of BiO3 polyhedra. 相似文献
89.
Hye Jin Heo Hyoung Kyu Kim Jae Boum Youm Sung Woo Cho In-Sung Song Sun Young Lee Tae Hee Ko Nari Kim Kyung Soo Ko Byoung Doo Rhee Jin Han 《Experimental & molecular medicine》2016,48(8):e254
Mitochondria are crucial for maintaining the properties of embryonic stem cells (ESCs) and for regulating their subsequent differentiation into diverse cell lineages, including cardiomyocytes. However, mitochondrial regulators that manage the rate of differentiation or cell fate have been rarely identified. This study aimed to determine the potential mitochondrial factor that controls the differentiation of ESCs into cardiac myocytes. We induced cardiomyocyte differentiation from mouse ESCs (mESCs) and performed microarray assays to assess messenger RNA (mRNA) expression changes at differentiation day 8 (D8) compared with undifferentiated mESCs (D0). Among the differentially expressed genes, Pdp1 expression was significantly decreased (27-fold) on D8 compared to D0, which was accompanied by suppressed mitochondrial indices, including ATP levels, membrane potential, ROS and mitochondrial Ca2+. Notably, Pdp1 overexpression significantly enhanced the mitochondrial indices and pyruvate dehydrogenase activity and reduced the expression of cardiac differentiation marker mRNA and the cardiac differentiation rate compared to a mock control. In confirmation of this, a knockdown of the Pdp1 gene promoted the expression of cardiac differentiation marker mRNA and the cardiac differentiation rate. In conclusion, our results suggest that mitochondrial PDP1 is a potential regulator that controls cardiac differentiation at an early differentiation stage in ESCs. 相似文献
90.
Hyun Ju Park Jong-Ki Jeon Dong Jin Suh Young-Woong Suh Hyeon Su Heo Young-Kwon Park 《Catalysis Surveys from Asia》2011,15(3):161-180
Bio-oil has attracted considerable interest as a promising renewable energy resource because it can be utilized as a feedstock
in integrated bio-refineries for the production of highly valuable chemicals and next-generation hydrocarbon fuels. However,
it is necessary to improve the bio-oil quality before it can be fed to bio-refineries. Currently, catalytic vapor cracking
seems a more attractive process than catalytic upgrading technologies, such as hydrotreating and esterification, in order
to improve the bio-oil quality. This review presents a summary of recent research and the state of art technology for the
catalytic vapor cracking of bio-oil, focusing on the catalysts applied, upgrading methods and reaction mechanisms. 相似文献