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排序方式: 共有197条查询结果,搜索用时 31 毫秒
71.
Hayoung Jeon Seonuk Park Sooji Nam Kwonwoo Shin Sung‐Ryong Kim Se Hyun Kim Jaeyoung Jang Tae Kyu An 《中国化学》2016,34(11):1103-1108
We investigated the effects of the multilayer polymer‐clay nanohybrid passivation films on the stability of pentacene organic thin‐film transistors (OTFTs) exposed to air and UV irradiation. Well‐ordered multilayer films were deposited by the spin‐assisted layer‐by‐layer assembly method using photocrosslinkable poly(vinyl alcohol) with the N‐methyl‐4(4′‐formylstyryl)pyridinium methosulfate acetal group (SbQ‐PVA) and Na+‐montmorillonite in a water‐based solution process. When photocrosslinked, these SbQ‐PVA/clay multilayers were found to serve as excellent barriers to O2 and UV‐light. Moreover, when used as passivation layers, they enhanced the stability of pentacene OTFT devices exposed to air and UV radiation. 相似文献
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Highly stable diphenylalanine peptide nanowires were selectively self-assembled in the reaction zone of a microfluidic system and applied for microchemical hydrogenation and Suzuki coupling reactions through the hybridization of Pd nanoparticles. 相似文献
75.
Yu DH Yi JK Yuh HS Park SJ Kim HJ Bae KB Ji YR Kim NR Park SJ Kim do H Kim SH Kim MO Lee JW Ryoo ZY 《Experimental & molecular medicine》2012,44(9):529-535
Oxidative stress such as reactive oxygen species (ROS) within the inflamed joint have been indicated as being involved as inflammatory mediators in the induction of arthritis. Correlations between extracellular- superoxide dismutase (EC-SOD) and inflammatory arthritis have been shown in several animal models of RA. However, there is a question whether the over-expression of EC-SOD on arthritic joint also could suppress the progression of disease or not. In the present study, the effect on the synovial tissue of experimental arthritis was investigated using EC-SOD over-expressing transgenic mice. The over-expression of EC- SOD in joint tissue was confirmed by RT-PCR and immunohistochemistry. The degree of the inflammation in EC-SOD transgenic mice was suppressed in the collagen-induced arthritis model. In a cytokine assay, the production of pro-inflammatory cytokines such as, IL-1β, TNFα, and matrix metalloproteinases (MMPs) was decreased in fibroblast-like synoviocyte (FLS) but not in peripheral blood. Histological examination also showed repressed cartilage destruction and bone in EC-SOD transgenic mice. In conclusion, these data suggest that the over-expression of EC-SOD in FLS contributes to the activation of FLS and protection from joint destruction by depressing the production of the pro-inflammatory cytokines and MMPs. These results provide EC-SOD transgenic mice with a useful animal model for inflammatory arthritis research. 相似文献
76.
Young Mi Ha Yohei Uehara Daeui Park Hyoung Oh Jeong Ji Young Park Yun Jung Park Ji Yeon Lee Hye Jin Lee Yu Min Song Hyung Ryong Moon Hae Young Chung 《Applied biochemistry and biotechnology》2012,168(6):1416-1433
We describe the design, synthesis, and biological activities of 5-chloro-2-(substituted phenyl)benzo[d]thiazole derivatives as novel tyrosinase inhibitors. Among them, 4-(5-chloro-2,3-dihydrobenzo[d]thiazol-2-yl)-2,6-dimethoxyphenol (MHY884) and 2-bromo-4-(5-chloro-benzo[d]thiazol-2-yl)phenol (MHY966) showed inhibitory activity higher than or similar to kojic acid, against mushroom tyrosinase. Therefore, we carried out kinetic studies on the two compounds with potent tyrosinase inhibitory effects. Kinetic analysis of tyrosinase inhibition revealed that all of these compounds are competitive inhibitors. MHY884 and MHY966 effectively inhibited tyrosinase activity and reduced melanin levels in B16 cells treated with ??-melanocyte stimulating hormone (??-MSH). These data strongly suggest that the newly synthesized compounds MHY884 and MHY966 could suppress production of melanin via inhibition of tyrosinase activity. 相似文献
77.
We show existence and regularity of solution for the compressible viscous steady state Navier–Stokes system on a polygon having a grazing corner and that the density has a jump discontinuity across a curve inside the domain. There are corresponding jumps in derivatives of the velocity. The solution comes from a well-posed boundary value problem on a polygonal domain with a non-convex corner. A formula for the decay of the jump is given. The decay formula suggests that density jumps can occur in a compressible flow with a non-vanishing viscosity. 相似文献
78.
Heejeong Choi Il Young Ryu Inkyu Choi Sultan Ullah Hee Jin Jung Yujin Park Yeongmu Jeong YeJi Hwang Sojeong Hong In-Soo Yoon Hwayoung Yun Min-Soo Kim Jin-Wook Yoo Yunjin Jung Pusoon Chun Hyung Ryong Moon 《Molecules (Basel, Switzerland)》2021,26(16)
To confirm that the β-phenyl-α,β-unsaturated thiocarbonyl (PUSTC) scaffold, similar to the β-phenyl-α,β-unsaturated carbonyl (PUSC) scaffold, acts as a core inhibitory structure for tyrosinase, twelve (Z)-5-(substituted benzylidene)-4-thioxothiazolidin-2-one ((Z)-BTTZ) derivatives were designed and synthesized. Seven of the twelve derivatives showed stronger inhibitory activity than kojic acid against mushroom tyrosinase. Compound 2b (IC50 = 0.47 ± 0.97 µM) exerted a 141-fold higher inhibitory potency than kojic acid. Kinetic studies’ results confirmed that compounds 2b and 2f are competitive tyrosinase inhibitors, which was supported by high binding affinities with the active site of tyrosinase by docking simulation. Docking results using a human tyrosinase homology model indicated that 2b and 2f might potently inhibit human tyrosinase. In vitro assays of 2b and 2f were conducted using B16F10 melanoma cells. Compounds 2b and 2f significantly and concentration-dependently inhibited intracellular melanin contents, and the anti-melanogenic effects of 2b at 10 µM and 2f at 25 µM were considerably greater than the inhibitory effect of kojic acid at 25 µM. Compounds 2b and 2f similarly inhibited cellular tyrosinase activity and melanin contents, indicating that the anti-melanogenic effects of both were due to tyrosinase inhibition. A strong binding affinity with the active site of tyrosinase and potent inhibitions of mushroom tyrosinase, cellular tyrosinase activity, and melanin generation in B16F10 cells indicates the PUSTC scaffold offers an attractive platform for the development of novel tyrosinase inhibitors. 相似文献
79.
YANG Zunhua KIM Kyung Ran PARK Ah-Young LEE Hyung-Rock KANG Jin-Ah KIM Won Hee CHUN Pusoon GONG Ping LEE Boeun JEONG Lak Shin MOON Hyung Ryong 《中国化学》2009,27(12):2405-2412
Synthesis of north‐5'‐methylbicyclo[3.1.0]hexyl purine and pyrimidine nucleosides with an ethynyl group at C‐3' position has been successfully accomplished by a facile method. Methylbicyclo[3.1.0]hexanone (±)‐ 5 having three contiguous chiral centers was remarkably simply constructed only by four steps containing a carbenoid insertion reaction in the presence of rhodium(II) acetate dimer and CuSO4, giving a correct relative stereochemistry of the generated three chiral centers. Upon Grignard reaction of (±)‐ 5 with ethynylmagnesium bromide, exclusive diastereoselectivity was observed. Condensation of glycosyl donor (±)‐ 9 with purine nucleobase afforded only the desired N9‐alkylated nucleoside, while condensation with pyrimidine, N3‐benzoylated uracil gave the desired N1‐alkylated nucleoside (±)‐ 13 with the undesired O2‐alkylated nucleoside (±)‐ 14 . Probably, (±)‐ 14 would be formed due to steric hindrance caused upon approaching for N1‐alkylation. 相似文献
80.
Mehmet Onur Cetin Seong Ryong Koh Matthias Meinke Wolfgang Schröder 《Comptes Rendus Mecanique》2018,346(10):932-947
A hybrid computational fluid dynamics (CFD) and computational aeroacoustics (CAA) method is used to compute the acoustic field of turbulent hot jets at a Reynolds number and a Mach number . The flow field computations are performed by highly resolved large-eddy simulations (LES), from which sound source terms are extracted to compute the acoustic field by solving the acoustic perturbation equations (APE). Two jets are considered to analyze the impact of exit conditions on the resulting jet sound field. First, a jet emanating from a fully resolved non-generic nozzle is simulated by solving the discrete conservation equations. This computation of the jet flow is denoted free-exit-flow (FEF) formulation. For the second computation, the nozzle geometry is not included in the computational domain. Time averaged exit conditions, i.e. velocity and density profiles of the first formulation, plus a jet forcing in form of vortex rings are imposed at the inlet of the second jet configuration. This formulation is denoted imposed-exit-flow (IEF) formulation. The free-exit-flow case shows up to 50% higher turbulent kinetic energy than the imposed-exit-flow case in the jet near field, which drastically impacts noise generation. The FEF and IEF configurations reveal quite a different qualitative behavior of the sound spectra, especially in the sideline direction where the entropy source term dominates sound generation. This difference occurs since the noise sources generated by density and pressure fluctuations are not perfectly modeled by the vortex ring forcing method in the IEF solution. However, the total overall sound pressure level shows the same qualitative behavior for the FEF and IEF formulations. Towards the downstream direction, the sound spectra of the FEF and IEF solutions converge. 相似文献