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241.
Chitosan and konjac glucomannan (KGM) blend fibers were prepared by spinning their solution through a viscose‐type spinneret into a coagulating bath containing aqueous sodium hydroxide and ethanol. The structure and properties of the blend fibers were studied with the aids of infrared spectra (IR), scanning electron micrography (SEM) and X‐ray diffraction (XRD). The structure analysis indicated that there were strong interaction and good miscibility between the chitosan and KGM molecule which resulted from intermolecular hydrogen bonds. Mechanical properties and water‐retention properties were measured. Through controlling blend conditions, blend fibers can obtain better mechanical properties than the pure chitosan fiber. The water‐retention values (WRV) of blend fibers increase as the amount of KGM is raised. The fibers treated with alcoholic solution of acetic acid have good antibacterial activity to Staphylococcus aureus. 相似文献
242.
Xueying Wang Zhangcheng Liao Tianqi Wang Haixia Lin Zixing Wang Yongmei Cui 《中国化学快报》2020,31(1):64-66
Two novel 2-(4-(9,9-disubstitued-9 H-fluoren-2-yl)phenyl)-9,9-diethyl-l-phenyl-1,9-dihydrofluoreno-[2,3-d]imidazole derivatives 2 a and 2 b were synthesized and characterized.Their photophysical and electrochemical properties,thermal stability property,and electroluminescence(EL)performance of 2 b were investigated.The fabricated device based on 2 b doping into 4,4’-N,N’-dicarbazole-biphenyl(5%)as an emitter present a maximum brightness of 1272 cd/m^2 at 4 V with the CIE coordinate of(0.1590,0.0465). 相似文献
243.
244.
The extracellular polysaccharides from Ganoderma lucidum possess low molecular weight and are mainly composed of (1 → 3)/(1 → 6) linked-α-glucan and (1 → 3)/(1 → 6) linked-α-galactose. In the present study, conformations of the polysaccharides were simulated and investigated using Discovery studio 2.5. Their sulfated derivatives were also taken into account. The simulation was performed using CHARMM force field. The results show that the polysaccharides exist as random coil conformations, while the sulfated derivatives adopt more extensive and stiffer conformations in most cases. In addition, the molecular docking between polysaccharide and human serum albumin (HSA) was also investigated using ZDOCK module in Discovery studio 2.5. It is shown that the unmodified polysaccharide possesses higher affinity with HSA than the sulfated derivatives do due to its higher ZDOCK score. 相似文献
245.
Yongmei Pan Shanjia Xu Ke Wu 《International Journal of Infrared and Millimeter Waves》2006,27(7):961-974
A new millimeter wave leaky wave antenna is presented in this paper, which is a modification of the groove guide with an asymmetric
conductor strip by introducing a dielectric slab into the conductor plane region of the groove guide antenna. The leakage
property of the new antenna is carefully examined through calculations of an equivalent network, which is developed here with
taking into account the coupling between different modes to guarantee the calculating accuracy. It has been found that the
new leaky wave antenna is of larger leakage constant than that for the original groove guide antenna because of the introduction
of the dielectric slab. Extensive numerical results of the leakage characteristics are given to establish useful guidelines
for the design of the new type groove guide leaky wave antenna. 相似文献
246.
Yongmei Liu Wei Huang Yansheng Zhao Tao Dou 《Reaction Kinetics and Catalysis Letters》2009,96(1):157-163
Nano Cu-Zn-Al-ZSM-5 was directly synthesized in HCl solutions with the promotion of ultrasound. XRD results show that the
appropriate concentrations of HCl in the synthetic process were between 0.25 M and 1 M, and the optimal crystallization time
and temperature were 28 h and 200°C, respectively. The ultrasound irradiation can significantly increase the crystallization
of Cu-Zn-Al-ZSM-5 within 0.5 h. SEM photographs of Cu-Zn-Al-ZSM-5 zeolite showed the crystal size is about 50–60 nm. Results
of ICP/AES show that the weight% of Cu in 101(Cu-Zn-Al-SOD) and 202(Cu-Zn-Al-ZSM-5) were 4.42% and 2.30%, respectively. 相似文献
247.
248.
通过溶液纺丝法制备了海藻酸盐/羧丁酰壳聚糖共混纤维,通过红外光谱、X射线衍射和光学显微镜对共混纤维进行表征.结果表明:共混体系中两种组分之间存在较强的相互作用,且有良好的相容性.当羧丁酰壳聚糖的含量为30%时,共混纤维的干态抗张强度达到最大值(14.32 cN/tex), 共混纤维的湿态抗张强度随着羧丁酰壳聚糖含量的增加而降低.当羧丁酰壳聚糖的含量为30%时,纤维的干、湿态断裂伸长率分别达到最大值43.5%和69.3%.随着羧丁酰壳聚糖的引入,纤维的吸水率显著提高.将纳米银分散液加入纺丝液中可以得到抗菌性能优异的海藻酸盐复合纤维. 相似文献
249.
A good yielding phase‐transfer‐catalyzed procedure for one‐pot preparation of α‐hydroxy acids from carbonyl compounds and sodium trichloroacetate by in situ addition and hydrolysis under microwave irradiation is described. Decomposition of sodium trichloroacetate is strongly accelerated by the presence of quaternary ammonium. The reaction can be conducted in water. 相似文献
250.
A class of chiral ligands has been developed by combining phenanthroline with quinine in a one-step method that does not require resolution. The synthesized three ligands were then coordinated with Cu(II) and the performance of the resultant chiral catalysts in the asymmetric Henry reaction was evaluated. Moderate to good yields (up to 86%) with high enantioselectivities (up to 99% ee) were observed in the reactions catalyzed by one of the three catalysts. Theoretical calculations were performed to analyze the catalytic activities of the different Cu(II)-ligand catalysts. Three different ligands were investigated and one ligand was found to adopt an unexpected five-coordinated mode; the second coordinated with two nitrogen atoms of phenanthroline to give a complex, which activated both substrates of Henry reaction; the third was unable to form a complex with Cu(II). 相似文献