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91.
Korakot Sombatmankhong Orawan Suwantong Suchada Waleetorncheepsawat Pitt Supaphol 《Journal of Polymer Science.Polymer Physics》2006,44(19):2923-2933
Electrospinning of poly(3‐hydroxybutyrate) (PHB), poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV), and their blends was first carried out in chloroform at 50 °C on a stationary collector. The average diameter of the as‐spun fiber from PHB and PHBV solutions decreased with increasing collection distance and increased with increasing solution concentration and applied electrical potential. In all of the spinning conditions investigated, the average diameter of the as‐spun pure fibers ranged between 1.6 and 8.8 μm. Electrospinning of PHB, PHBV, and their blends was carried out further at a fixed solution concentration of 14% w/v on a homemade rotating cylindrical collector. Well‐aligned, cross‐sectionally round fibers without beads were obtained. The average diameter of the as‐spun pure and blend fibers ranged between 2.3 and 4.0 μm. The as‐spun fiber mats appeared to be more hydrophobic than the corresponding films and much improvement in the tensile strength and the elongation at break was observed for the blend fiber mats over those of the pure fiber ones. Lastly, indirect cytotoxicity evaluation of the as‐spun pure and blend fiber mats with mouse fibroblasts (L929) indicated that these mats posed no threat to the cells. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2923–2933, 2006 相似文献
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Nawong Boonnak Suchada Chantrapromma Hoong-Kun Fun Surat Laphookhieo 《Tetrahedron》2006,62(37):8850-8859
Ten new compounds (1-10), pruniflorone A-J, together with 21 known compounds (11-31) were isolated from the roots and barks of Cratoxylum formosum ssp. pruniflorum. Their structures were determined by spectroscopic methods. Compounds 1 and 11 were also confirmed by X-ray diffraction data. In addition, antibacterial and cytotoxic activities of the isolates were also evaluated. 相似文献
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Anwar Usman Ibrahim Abdul Razak Hoong‐Kun Fun Suchada Chantrapromma Yan Zhang Jian‐Hua Xu 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(4):o239-o241
The crystal of the title compound, C20H17NO4, which was used for collecting intensity data was twinned. Each of the two crystallographically independent molecules in the asymmetric unit has a planar indole moiety perpendicular to a planar oxopropyl moiety. The distribution of the bonds at the central C atom joining the oxopropyl, phenyl and indole substituents is also planar. The packing is stabilized by intermolecular C—H?O interactions, as well as by dipole–dipole and van der Waals interactions. 相似文献
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Rajca A Pink M Rojsajjakul T Lu K Wang H Rajca S 《Journal of the American Chemical Society》2003,125(28):8534-8538
Synthesis, crystallography, and magnetic characterization of a stable macrocyclic tetranitroxide 1, a calix[4]arene, which is functionalized with four tert-butylnitroxides at the upper rim, is described. In solution, 1 has a 4-fold symmetric fixed cone conformation on the NMR time scale and small, but nonnegligible, exchange interactions between the radicals (30 K > /J/k/ >1.8 mK). In the solid state, dimerization of one diagonal pair of nitroxides leads to a pinched cone conformation for 1 with strong intradimer antiferromagnetic coupling with /J/k/ = 200-300 K (singlet-triplet energy gap, DeltaE(ST) approximately 1 kcal/mol). 相似文献
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Ibrahim Abdul Razak S. Shanmuga Sundara Raj Suchada Chantrapromma Hoong-Kun Fun Yun-Shan Zhou Xiao-Zeng You 《Journal of chemical crystallography》2001,31(5):255-262
In the title compound (C11H6N2O)3·H3PMo12O40·3H2O(1), the -dodecamolybdophosphoric acid residue has the Keggin structure, with M–O distance ranging between 1.673(5) and 2.464(4) Å. The water molecules are involved in O–H···N and O–H···O intermolecular hydrogen bonds with the diazafluoren moiety and -dodecamolybdophosphoric acid respectively while the diazafluoren moiety and -dodecamolybdophosphoric acid are connected through C–H···O interactions. The O–H···O intermolecular hydrogen bonds form infinite chains of Mo12O40 units in which N···O contacts interconnect the chains to form layers. 相似文献
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Yang Jia‐Xiang Hu Zhang‐Jun Zhang Ze Tian Yu‐Peng Liu Qing‐Liang Chantrapromma Suchada Fun Hoong‐Kun 《中国化学》2005,23(5):533-538
Two new complexes [Zn2(phen)4(FCA)2](ClO4)2·(H2O)2 ( 1 ) and [Co2(phen)4 (FCA)2](ClO4)2·(H2O)2 (2) (FCA=anion of 3‐ferrocenyl‐2‐crotonic acid, phen=1,10‐phenanthroline) have been synthesized, and characterized by elemental analysis, IR, UV‐Vis spectra, thermal analyses, and single‐crystal X‐ray diffraction. Two M(II) (M=Zn or Co) ions are bridged by two FCA anions with syn‐anti bridging ligands, leading to dimeric cores, [M2(phen)4(FCA)2]2+, and each M(II) ion is six‐coordinated in a distorted octahedral geometry by two chelate phen ligands and two μ2‐carboxylate oxygen atoms from two FCA groups. The M(II)…M(II) intradimer distances are 0.4391 and 0.4462 nm in 1 and 2 , respectively. Electrochemical properties of the complexes have been discussed. 相似文献
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Miyasaka M Rajca A Pink M Rajca S 《Journal of the American Chemical Society》2005,127(40):13806-13807
(-)-Sparteine-mediated asymmetric synthesis of di-n-octyl-substituted carbon-sulfur [11]helicene, a helical (C2S)n beta-undecathiophene, is described. The atom-efficient routes rely on one-step tri-annelation or two-step di- and mono-annelation to provide enantiomeric excess of (+)- or (-)-[11]helicene, respectively. X-ray structures for homologous [11] and [7]helicenes indicate similar helical curvatures. The optical band gap, Eg approximately 3.5 eV, is estimated for the (C2S)n helix polymer, with onset of electron localization at n = 7. 相似文献
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The two types of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)s [P(3HB-co-3HV)s] were produced by Paracoccus denitrificans ATCC 17741 using two different feeding methods. The produced P(3HB-co-3HV)s were fractionated and the copolymer sequence distributions were analyzed by 1H and 13C NMR spectroscopy. It was found that the P(3HB-co-3HV) samples produced by conventional feeding method were statistically random copolymers. The sequence distributions of P(3HB-co-3HV) samples produced by optimization method were different from random P(3HB-co-3HV)s. The thermal properties and melting behaviors were analyzed by differential scanning calorimetry (DSC). These results demonstrated that P(3HB-co-3HV) samples produced by optimization method are close in nature to P(3HB-co-3HV)s rich in long-sequence of block 3HB units, but less in 3HV random regions. The enzymatic degradation profile of P(3HB-co-3HV) films was investigated in the presence of 3-hydroxybutyrate depolymerase from Pseudomonase lemoignei. The degradation process was observed by monitoring the time-dependent change in the weight loss of copolymer films. The surface erosion of copolymer films was qualitatively monitored by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The highest degradation rate of 2.6% per day was observed for random P(3HB-co-38%3HV) produced by conventional method. In comparison, the hydrolysis degradation rates of random P(3HB-co-3HV)s were about one time faster than those of P(3HB-co-3HV)s produced by optimization method. 相似文献