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排序方式: 共有224条查询结果,搜索用时 15 毫秒
1.
Seong-Jai Cho Chang-Do Um Seock-Sam Kim 《Journal of the American Ceramic Society》1996,79(5):1247-1251
Wear and wear transition in silicon carbide ceramics during sliding have been investigated. Three different microstructures, i.e., solid-state-sintered silicon carbide, liquidphase-sintered silicon carbide, and a liquid-phase-sintered SiC-TiB2 composite, were produced by hot pressing. Wear data and examinations of worn surfaces showed that the wear behavior of these silicon carbide ceramics was significantly different. In the solid-state-sintered silicon carbide, the wear occurred by a grooving process. In the liqudphase-sintered silicon carbide and composite, on the other hand, an abrupt transition in the wear mechanism from an initial grooving process to a grain pullout process occurred during the test. The transition occurred significantly earlier in the composite than in the carbide. The different wear behavior in these silicon carbide ceramics is discussed in relation to the grain or interphase boundary strength. 相似文献
2.
Jung-Ho Um Yong-Ki Kim Hyun-Jo Lee Miyoung Jang Jae-Woo Chang 《Journal of Systems Architecture》2012,58(9):354-371
Due to the advancement of wireless internet and mobile positioning technology, the application of location-based services (LBSs) has become popular for mobile users. Since users have to send their exact locations to obtain the service, it may lead to several privacy threats. To solve this problem, a cloaking method has been proposed to blur users’ exact locations into a cloaked spatial region with a required privacy threshold (k). With the cloaked region, an LBS server can carry out a k-nearest neighbor (k-NN) search algorithm. Some recent studies have proposed methods to search k-nearest POIs while protecting a user’s privacy. However, they have at least one major problem, such as inefficiency on query processing or low precision of retrieved result. To resolve these problems, in this paper, we propose a novel k-NN query processing algorithm for a cloaking region to satisfy both requirements of fast query processing time and high precision of the retrieved result. To achieve fast query processing time, we propose a new pruning technique based on a 2D-coodinate scheme. In addition, we make use of a Voronoi diagram for retrieving the nearest POIs efficiently. To satisfy the requirement of high precision of the retrieved result, we guarantee that our k-NN query processing algorithm always contains the exact set of k nearest neighbors. Our performance analysis shows that our algorithm achieves better performance in terms of query processing time and the number of candidate POIs compared with other algorithms. 相似文献
3.
Chung-In Um In-Han Kim Yeon-Mu Choi Thomas F. George 《Journal of Low Temperature Physics》1994,95(3-4):547-578
The temperature variations of the diffusion coefficientD(T), thermal diffusion ratio k
T
(T) and thermal conductivity (T) in a dilute solution of3He atom in two-dimensional liquid helium are evaluated explicitly by solving the kinetic equations via phonon-phonon, phonon-roton, roton-roton, impurityelementary excitation and impurity-impurity scatterings. In the low-temperature region, the main contributions toD(T) and (T) come from the interactions between phonons and impurities, while in the high-temperature region the interactions between impurities and whole elementary excitations contribute more strongly toD(T) and (T) than those of only elementary excitations. For a dilute solution, the thermal diffusion ratio k
T
(T), neglecting the internal mass counterflow, is much smaller than the effective thermal diffusion ratio k
T
*
(T), which is a function of thermostatic properties. The effective thermal conductivity eff is much larger than the thermal conductivity and has different temperature dependence from the thermal conductivity. The behaviors of the two-dimensional diffusion coefficient and thermal conductivity are much like the bulk case, where they exhibit exponential decay with increasing temperature, although they are much smaller than those of the bulk case. 相似文献
4.
Yun Hee Sim Yun Jung Um Jeong-Yang Park Min-Duk Seo Sang Gyu Park 《International journal of molecular sciences》2022,23(20)
Ovarian cancer is the fifth leading cause of cancer, followed by front line is mostly platinum agents and PARP inhibitors, and very limited option in later lines. Therefore, there is a need for alternative therapeutic options. Nectin-2, which is overexpressed in ovarian cancer, is a known immune checkpoint that deregulates immune cell function. In this study, we generated a novel anti-nectin-2 antibody (chimeric 12G1, c12G1), and further characterized it using epitope mapping, enzyme-linked immunosorbent assay, surface plasmon resonance, fluorescence-activated cell sorting, and internalization assays. The c12G1 antibody specifically bound to the C2 domain of human nectin-2 with high affinity (KD = 2.90 × 10−10 M), but not to mouse nectin-2. We then generated an antibody-drug conjugate comprising the c12G1 antibody conjugated to DM1 and investigated its cytotoxic effects against cancer cells in vitro and in vivo. c12G1-DM1 induced cell cycle arrest at the mitotic phase in nectin-2-positive ovarian cancer cells, but not in nectin-2-negative cancer cells. c12G1-DM1 induced ~100-fold cytotoxicity in ovarian cancer cells, with an IC50 in the range of 0.1 nM~7.4 nM, compared to normal IgG-DM1. In addition, c12G1-DM1 showed ~91% tumor growth inhibition in mouse xenograft models transplanted with OV-90 cells. These results suggest that c12G1-DM1 could be used as a potential therapeutic agent against nectin-2-positive ovarian cancers. 相似文献
5.
Je-Hyuk Lee Tae Ho Kang Byung Hun Um Eun-Hwa Sohn Woo-Cheul Han Seol-Hee Ji Ki-Hyo Jang 《Food science and biotechnology》2013,22(4):1039-1046
To evaluate the possibility for development of apple wine containing medicinal herbs, we have prepared ‘Fuji’ apple (Malus domestica) wines containing pine (Pinus densiflora Siebold et Zuccarini) needle and hwanggi (Radix Astragali)/mistletoe (Viscum album). Normal apple wine was fermented rapidly, but after 40 days fermentation/maturation, the final ethanol content, pH, total acidity, and contents of sugar/organic acid showed similar levels in 3 kinds of apple wines. In other hands, the total phenols content, antocyanins content, and brightness were higher in apple-pine wine and apple-herb wine than in normal apple wine. Apple-herb wine had higher values in total phenol contents, brightness, free amino acid contents, and quenching activity for ABTS free radicals than normal apple wine, and had similar sensory evaluation values with normal apple wine. Taken together, it is supposed that hwanggi and mistletoe might provide functional components to normal apple wine and might be applied to development of functional apple wines. 相似文献
6.
Hydrothermal fractionation for micro-algae, Schizocytrium sp., was investigated to separate sugars, lipids, and proteins. This fractionation process produced protein-rich solid cake
and liquid hydrolysates, which contained oligomeric sugars and lipids. Oligomeric sugars and lipids were easily separated
by liquid-liquid separation. Sugars in the separated hydrolyzate were determined to be mainly D-glucose and L-galactose. Fractionation
conditions were optimized by response surface methodology (RSM). Optimal conditions were found to be 115.5 °C of reaction
temperature, 46.7 min of reaction time, and 25% (w/w) of solid loading. The model predicted that maximum oligomeric sugar
yield (based on untreated micro-algae weight), which can be recovered by hydrothermal fractionation at the optimum conditions,
was 19.4 wt% (based on the total biomass weight). Experimental results were in agreement with the model prediction of 16.6
wt%. Production of bioethanol using micro-algae-induced glucan and E. coli KO11 was tested with SSF (simultaneous saccharification and fermentation), which resulted in 11.8 g-ethanol/l was produced from 25.7 g/l of glucose; i.e. the theoretical maximum ethanol yield based on glucan in hydrolyzate was 89.8%. 相似文献
7.
Drug‐loaded microparticles prepared by the one‐step deposition of calcium carbonate/alginate onto cotton fabrics 下载免费PDF全文
Huan‐Ling Wu Xiao‐Xiao Hou Christopher Branford‐White Xiao‐Zhu Sun Lei Tao Syeda Um‐I‐Zahra Li‐Min Zhu 《应用聚合物科学杂志》2015,132(40)
Calcium carbonate (CaCO3)/alginate inorganic–organic hybrid particles were synthesized and deposited on to the surface of cotton fabrics with a novel one‐step procedure. The effects of the Ca2+/CO32?/alginate molar ratio on the cotton matrix were investigated. The optimization of the process resulted in a regular shaped hybrid microparticles, and scanning electron microscopy revealed that the particles were uniformly distributed on the surface of the fibers. Dynamic light scattering showed that the particles were about 2 μm in diameter. Moreover, transmission electron microscopy images demonstrated that the core–shell structure of the particles existed along with CaCO3 evenly enfolded into the alginate layer. An X‐ray diffraction pattern displayed that the alginate/CaCO3 hybrid microparticles were a mixture of calcite and vaterite crystal. Fourier transform infrared spectroscopy indicated that CaCO3/alginate hybrid particles formed in situ were the only deposited materials. The thermogravimetric analysis curve indicated a certain mass ratio of the alginate and CaCO3 in the hybrid particles. Furthermore, the drug‐loading and drug‐release properties of the hybrid microspheres were studied, and the results show that the water‐soluble diclofenac sodium could be effectively loaded in the hybrid microparticles and the drug release could be effectively sustained. Finally, both of the microparticles and modified fabrics had good cytocompatibility. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42618. 相似文献
8.
Crude extract and solvent-partitioned fraction of Glehnia littoralis were found to possess different anti-proliferative effects against AGS, HT1080 and U937 human cancer cells. The crude extracts and solvent fractions dose-dependently inhibited cell proliferation. Especially, n-hexane and 85% aqueous MeOH fractions exhibited comparatively higher anti-proliferative effects and reduced expressions of Bcl-2, COX-2 and iNOS genes. Systematic separation of all solvent fractions by chromatographic methods led to the isolation of three glucopyranosides, four furanocoumarins and two polyacetylenic alcohols. All the nine compounds were evaluated for their inhibitory effects against both proliferation of human cancer cells and expressions of MMP-2 and -9 in HT1080 cells. Two polyacetylenic alcohols exerted the highest inhibitory activity against both human cancer cell lines, and MMP-2 and -9. These results suggest that G. littoralis may possibly be used as a valuable chemopreventive agent or food supplement for reducing cancer risk. 相似文献
9.
Igor N. Adamenko Konstantin E. Nemchenko Alexander V. Zhukov Chung-In Um Thomas F. George Lakshmi N. Pandey 《Journal of Low Temperature Physics》1998,111(1-2):145-179
Starting from the system of linearized kinetic equations, the exact expressions for the spin and mass diffusion coefficients and thermal diffusion ratio in quantum mixtures of helium isotopes with any degree of degeneration is obtained. From the general expression the various limiting expressions have been obtained, which are determined by various relations between collision rates of quasiparticles. The results of the calculations are compared with available experimental data. It is shown that in the low-temperature region, where an impuriton gas is one-component, the relaxation of concentration of
3
He in superfluid
3
He–
4
He mixtures is determined by the acoustic and dissipative collective modes with an effective diffusion coefficient. From the general relation, the expression for a spin diffusion coefficient in solid
3
He–
4
He quantum mixtures is derived. The comparison of the results obtained with the experimental data makes it possible to find a numerical value for the width of the impuriton energy zone. 相似文献
10.