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51.
Min Hyuk Park Han Joon Kim Yu Jin Kim Taehwan Moon Keum Do Kim Cheol Seong Hwang 《固体物理学:研究快报》2014,8(10):857-861
With increasing annealing temperature (Tanneal), the magnitude of the electric fields for the antiferroelectric‐to‐ferro‐electric (EAF) and ferroelectric‐to‐antiferroelectric (EFA) transition of a 9.2 nm thick Hf0.3Zr0.7O2 film decreased. The energy storage densities of the Hf0.3Zr0.7O2 films crystallized at 400 °C, 500 °C, and 600 °C were as large as 42.2 J/cm3, 40.4 J/cm3, and 28.3 J/cm3, respectively, at the electric field of 4.35 MV/cm. The maximum dielectric constant of the Hf0.3Zr0.7O2 film crystallized at 600 °C was the largest (~46) as it had the smallest EAF and EFA, whereas the leakage current density of the film crystallized at 400 °C was the smallest. The 400 °C of Tanneal was the optimum condition for energy storage application. (© 2014 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
52.
Three possible mechanistic routes for the diastereomeric isomerization of the leuco-triarymethane (LTAM) molecules have been proposed, depending on the formal breaking of the carbon-carbon double bond via either heterolytic, homolytic or molecula splitting/reassembling. 相似文献
53.
Two series of new liquid crystalline compounds containing a non-activated arylazoindolinobenzospiropyran, ABP-SPAB 1a-1e (series 1) and SPAP-ABPC 2a-2e (series 2), have been synthesized. These LC dyes were characterized by a differential scanning calorimetry polarizing optical microscopy, X-ray diffraction and electro-optical measurements. All but one of the series 1 compounds examined exhibit monotropic second and/or third transition liquid crystal phases on cooling from the isotropic liquid. In particular, ABP-SPAB 1b shows a monotropic SmC phase, in addition to a SmA phase. In series 2, most of the compounds exhibit a monotropic nematic phase on cooling. SPAP-ABPC 2c forms an enantiotropic nematic phase and a monotropic SmA phase; 2e shows enantiotropic nematic and SmA phases. 相似文献
54.
Jung SH Park SY Kim-Pak Y Lee HK Park KS Shin KH Ohuchi K Shin HK Keum SR Lim SS 《Chemical & pharmaceutical bulletin》2006,54(3):368-371
Fifteen chalcones and three thiazolidinedione (TZD) chalcones were prepared to evaluate their peroxisome proliferator-activated receptor-gamma (PPAR-gamma) ligand-binding activities. Among the three TZDs, one compound possessed PPAR-gamma transactivation potential, while the others showed antagonistic activity against PPAR-gamma transactivation. Among the chalcones, compound 5 was the most potent, and structure-activity relationship studies indicated that a methoxyl group in position C-4 and hydroxyl group in position C-4' or 5' in chalcone plays a key role in determining the potency of PPAR-gamma activation. 相似文献
55.
Jeum-Jong Kim Ock Keum Kwak Jong Keun Park Kil Sik Min Yong-Jin Yoon 《Journal of inclusion phenomena and macrocyclic chemistry》2014,79(3-4):495-502
The potentially tridentate ligands 4-(6-(pyridin-4-yl)pyridin-2-yl)pyridine (4) and 3-(6-(pyridin-3-yl)-pyridin-2-yl)pyridine (5) have been prepared and characterized. From the self-assembly of 4 or 5 and 2,9-bis[trans-Pt(PEt3)2(NO3)]phenanthrene (6), two supramolecular platinum-based macrocycles with rhomboid (7) and overlapped double rhomboid (8) structures have been constructed. Compounds 7 and 8 are formed in different shapes due to the different nitrogen positions (meta and para) of the ligands 4 and 5, respectively. Both supramolecules are characterized by multinuclear NMR and electrospray ionization mass spectroscopies. 相似文献
56.
5,5-Diamino-substituted-1,4,2-oxathiazoline derivatives 3 as potential prodrugs, which were easily prepared from hydroximoyl chlorides 1 and the appropriate thiourea derivatives 2, were decomposed instantaneously into isothiocyanates 4 and the corresponding urea derivatives 5 irrespective of the substituents. 相似文献
57.
JongHae Keum 《Topology》2006,45(5):919-927
A fake projective plane is a compact complex surface (a compact complex manifold of dimension 2) with the same Betti numbers as the complex projective plane, but not isomorphic to the complex projective plane. As was shown by Mumford, there exists at least one such surface.In this paper we prove the existence of a fake projective plane which is birational to a cyclic cover of degree 7 of a Dolgachev surface. 相似文献
58.
Mo S Kim DH Lee JH Park JW Basnet DB Ban YH Yoo YJ Chen SW Park SR Choi EA Kim E Jin YY Lee SK Park JY Liu Y Lee MO Lee KS Kim SJ Kim D Park BC Lee SG Kwon HJ Suh JW Moore BS Lim SK Yoon YJ 《Journal of the American Chemical Society》2011,133(4):976-985
The allyl moiety of the immunosuppressive agent FK506 is structurally unique among polyketides and critical for its potent biological activity. Here, we detail the biosynthetic pathway to allylmalonyl-coenzyme A (CoA), from which the FK506 allyl group is derived, based on a comprehensive chemical, biochemical, and genetic interrogation of three FK506 gene clusters. A discrete polyketide synthase (PKS) with noncanonical domain architecture presumably in coordination with the fatty acid synthase pathway of the host catalyzes a multistep enzymatic reaction to allylmalonyl-CoA via trans-2-pentenyl-acyl carrier protein. Characterization of this discrete pathway facilitated the engineered biosynthesis of novel allyl group-modified FK506 analogues, 36-fluoro-FK520 and 36-methyl-FK506, the latter of which exhibits improved neurite outgrowth activity. This unique feature of FK506 biosynthesis, in which a dedicated PKS provides an atypical extender unit for the main modular PKS, illuminates a new strategy for the combinatorial biosynthesis of designer macrolide scaffolds as well as FK506 analogues. 相似文献
59.
Shomura R Chung KJ Iwai H Higuchi M 《Langmuir : the ACS journal of surfaces and colloids》2011,27(13):7972-7975
New gold nanoparticles covered with cyclic phenylazomethine (CPA) were obtained by a one-pot synthesis. It is confirmed by XPS that imines of CPA in the nanoparticles (Au-CPA) are partially reduced to amines. The amine part of CPA in Au-CPA is attached to the surfaces of gold nanoparticles, and the imine part works as a redox-active site. A glassy carbon electrode modified with Au-CPA was revealed to work as an electrochemical probe for metal ion sensing. 相似文献
60.
Ajeesh Chandrasekharan Keum‐Yong Seong Sang‐Gu Yim Sodam Kim Sungbaek Seo Jinhwan Yoon Seung Yun Yang 《Journal of polymer science. Part A, Polymer chemistry》2019,57(4):522-530
Hyaluronic acid (HA), a naturally occurring linear polysaccharide, has been widely used as a key biomaterial in a range of cosmetic and therapeutic applications. Its excellent biocompatibility and bio‐functions related to tissue regeneration encourage the development of HA‐based hydrogels to expand its applications. This study details an in situ forming surgical glue based on photocrosslinkable HA, providing tunable mechanical properties and firm tissue adhesion under wet and dynamic conditions. Depending on the degree of photocrosslinkable methacrylate groups in HA polymer chains, the mechanical properties of hyaluronate methacrylate (HAMA) hydrogels prepared by UV photocrosslinking was improved. Ex vivo adhesion tests revealed that HAMA hydrogels exhibited 3‐fold higher shear adhesive strength compared to gelatin methacryloyl hydrogels and achieved firm adherence to the porcine skin tissue for several weeks. The high adhesive strength of HAMA hydrogels, under dry and wet conditions, suggests that it may have great promise as a tissue adhesive. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 522–530 相似文献