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361.
A series of novel chiral diphosphite ligands have been synthesized from (1R,2R)-trans-1,2-cyclohexanediol, (1S,2S)-trans-1,2-cyclohexanediol, racemic trans-1,2-cyclohexanediol and chlorophosphoric acid diary ester, and were successfully employed in the Cu-catalyzed asymmetric 1,4-conjugate addition of diethylzinc to cyclohexenone with up to 99% ee. It was found that ligand 1,2-bis[(R)-1,1'-binaphthyl-2,2'-diyl]phosphitecyclohexanediol 6a derived from racemic diol skeleton can show similar catalytic performance compared with ligand (1R,2R)-bis[(R)-1,1'-binaphthyl-2,2'-diyl]phosphitecyclohexanediol 6a' derived from enantiopure startingmaterial. A significant dependence of stereoselectivity on the type of enone and the ring size of the cyclic enone was observed. Moreover, the configuration of the products was mainly determined by the configuration of the binaphthyl moieties of diphosphite ligands in the 1,4-addition of cyclic enones. 相似文献
362.
目的了解肺炎支原体肺炎患儿急性期和恢复期血浆中H-ficolin、L-ficolin水平的变化。方法采用ELISA法检测85例肺炎支原体肺炎患儿急性期和恢复期血浆H-ficolin、L-ficolin水平,并进行相关性分析。结果急性期H-ficolin水平1.8~25.2μg/ml,平均(11.9±5.9)μg/ml,恢复期H-ficolin水平0.3~26.5μg/ml,平均(10.1±5.7)μg/ml,急性期明显高于恢复期(Z=2.161,P=0.031)。急性期L-ficolin水平0.2~10.6μg/ml,平均(4.5±2.3)μg/ml,恢复期L-ficolin水平0.03~10.2μg/ml,平均(4.6±2.2)μg/ml,急性期和恢复期无统计学差异(t=0.245,P=0.807)。患儿急性期血浆H-ficolin水平与L-ficolin水平明显相关(r=0.22,P=0.039)。结论H-ficolin可能参与儿童肺炎支原体肺炎疾病过程。 相似文献
363.
Guodong Huang Guomei Chen Wenchao Pang 《International Journal of Polymer Analysis and Characterization》2016,21(5):417-427
This article investigates irradiated and accelerated aged graphene oxide (GO)/ultrahigh molecular weight polyethylene (UHMWPE) nanocomposites. The prepared GO/UHMWPE nanocomposites are gamma-irradiated at a high irradiation dose in a vacuum and then accelerated aging procedure is performed at 80°C in an air oven for 21 days. Irradiated and aged samples are characterized by Raman spectrum, Fourier transform infrared (FT-IR) spectrum, differential scanning calorimetry, contact angle, and gel content. Filling GO reduces the intensity of Raman spectrum of UHMWPE and irradiation or aging cannot affect vibrational modes of UHMWPE and GO/UHMWPE. The result of the FT-IR spectrum shows that UHMWPE and GO/UHMWPE basically have the same oxidation index values, whether with irradiation or accelerated aging. Irradiation or aging can slightly increase the melting temperature. GO, irradiation, or aging can significantly increase the crystallinity and improve wetting properties. In irradiated GO/UHMWPE, GO is able to maintain the efficiency of the cross-linking. However, after aging, the cross-linking density of GO/UHMWPE is reduced significantly. According to the above results, it is proposed that GO shows a very weak scavenging free radicals capacity in GO/UHMWPE composites and cannot display antioxidant capacity. 相似文献
364.
Chunjing Zhang Zhuanfang Zhang Ying Guo Heng Liu Huiyuan Ma Bo Liu Haijun Pang Shaobin Li 《Structural chemistry》2016,27(2):439-447
Three new compounds [Mn(H2O)2(bimb)2(H3SiW12O40)2](bimb)4 (1), [Zn2(bimb)4(H2O)4][SiW12O40] (2), and [Ni2(bimb)4(H2O)4][SiW12O40] (3) (bimb = 1,3-bis(1-imidazoly)benzene) have been synthesized under the same hydrothermal reaction except for tuning the metal cations (Mn2+, Zn2+, and Ni2+). Structural characterizations show that the three compounds possess distinct structural motives. Compound 1 displays a supramolecular one-dimensional (1 D) chain formed by π···π interactions that occur among the almost parallel bimb ligands from adjacent [Mn(H2O)2(bimb)2(SiW12O40)2] dimers. Compound 2 shows a supramolecular two-dimensional (2D) layer achieved by intermolecular (C–H···O) hydrogen bondings between the Zn2(bimb)4 molecular loops and the SiW12 anions. Compound 3 also exhibits a supramolecular 2D layer, but it is different from 2, which is generated by the π···π interactions among adjacent 1D polymeric chains. The distinct structural features of the three compounds suggest that the metal cations should play a significant role in the process of assembly. Additionally, the electrochemical properties of compounds 1–3 have been investigated, and the results indicate that compounds 1–3 possess excellent electrocatalytic activity toward reduction of both iodated and nitrite molecules. 相似文献
365.
S. S. Qian X. L. Zhao L. H. Pang Z. L. You H. L. Zhu 《Russian Journal of Coordination Chemistry》2016,42(5):345-350
A new centrosymmetric mononuclear copper(II) complex [Cu(L)2](ClO4)2 (I) and a new centrosymmetric mononuclear nickel(II) complex [Ni(L)2(MeOH)2](ClO4)2 (II), where L is the zwitterionic ligand 2-bromo-4-chloro-6-[(2-methylammonioethylimino)methyl]phenolate, have been prepared from the Schiff base 2-bromo-4-chloro-6-[(2-methylaminoethylimino)methyl]phenol with copper perchlorate and nickel perchlorate, respectively. The complexes were characterized by elemental analysis, infrared spectra, and single-cyrstal X-ray diffraction (CIF files CCDC nos. 1408054 (I) and 1407973 (II)). Complex I crystallizes in the monoclinic space group P21/c with unit cell dimensions a = 7.7736(4), b = 21.608(1), c = 8.5194(4) Å, β = 93.907(2)°, V = 1427.7(1) Å3, Z = 2, R 1 = 0.0546, and wR 2 = 0.1531. Complex II crystallizes in the monoclinic space group P21/c with unit cell dimensions a = 21.324(3), b = 16.821(2), c = 9.425(1) Å, β = 90.114(2)°, V = 3380.5(7) Å3, Z = 4, R 1 = 0.0693, and wR 2 = 0.1627. The Cu atom in I is in square planar coordination, and the Ni atom in II is in octahedral coordination. 相似文献
366.
367.
Trace determination of organophosphate esters in environmental water samples with an ionogel‐based nanoconfined ionic liquid fiber coating for solid‐phase microextraction with gas chromatography and flame photometric detection
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Long Pang Rong Pang Liming Ge Liqing Zheng Jihong Zhao Hongzhong Zhang 《Journal of separation science》2016,39(22):4415-4421
Organophosphate esters, widely used as flame retardants and plasticizers, are regarded as a class of emerging pollutants. In this work, a novel approach was developed for the fabrication of a solid‐phase microextraction fiber by using hybrid silica‐based materials with immobilized ionic liquids with sol–gel technology, and the prepared solid‐phase microextraction fiber was then coupled with gas chromatography and flame photometric detection for the analysis of six organophosphate esters. The high loading of 1‐hexadecyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide was confined within the hybrid network. The developed solid‐phase microextraction fiber possesses a coating thickness of ~35 μm with good thermal stability and long lifetime. The parameters affecting the extraction efficiency such as extraction time, temperature, pH, and ionic strength of the sample solution were optimized. Under the optimized conditions, the limits of detection were in the range of 0.04?0.95 μg L?1, and the precision of the method assessed with repeatability and reproducibility of (RSD%) ?13 and ?29%, respectively. The proposed method was successfully applied to determine the six organophosphate esters in three real water samples, with recoveries in the range of 64.8?125.4% at two different spiking concentration levels. As a result, the proposed method demonstrated its potential for application in trace determination of organophosphate esters in actual water samples. 相似文献
368.
Multiresidue determination of 114 multiclass pesticides in flue‐cured tobacco by solid‐phase extraction coupled with gas chromatography and tandem mass spectrometry
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Jianmin Cao Weisong Yu Xueli Pang Yingnan Lin Jun Qiu 《Journal of separation science》2016,39(23):4629-4636
A sensitive and robust multiresidue method for the simultaneous analysis of 114 pesticides in tobacco was developed based on solid‐phase extraction coupled with gas chromatography and tandem mass spectrometry. In this strategy, tobacco samples were extracted with acetonitrile and cleaned up with a multilayer solid‐phase extraction cartridge Cleanert TPT using acetonitrile/toluene (3:1) as the elution solvent. Two internal standards of different polarity were used to meet simultaneous pesticides quantification demands in the tobacco matrix. Satisfactory linearity in the range of 10–500 ng/mL was obtained for all 114 pesticides with linear regression coefficients higher than 0.994. The limit of detection and limit of quantification values were 0.02–5.27 and 0.06–17.6 ng/g, respectively. For most of the pesticides, acceptable recoveries in the range of 70–120% and repeatabilities (relative standard deviation) of <11% were achieved at spiking levels of 20, 100, and 400 ng/g. Compared with the reported multiresidue analytical method, the proposed method provided a cleaner test solution with smaller amounts of pigments, fatty acids as well as other undesirable interferences. The development and validation of the high sensitivity, high selectivity, easy automation, and high‐throughput analytical method meant that it could be successfully used for the determination of pesticides in tobacco samples. 相似文献
369.
Mengjiao Xu Minxuan Wang Hao Xu Prof. Dr. Huaiguo Xue Prof. Dr. Huan Pang 《化学:亚洲杂志》2016,11(21):2967-2995
Electrospinning, as a novel nontextile filament technology, is an important method to prepare continuous nanofibers and has shown its remarkable advantages, such as a broadly applicable material system, controllable fiber size and structure, and simple process. Electrospun nanofiber membranes prepared by electrospinning have shown promising applications in many fields, such as supercapacitors, lithium‐ion batteries, and sodium‐ion batteries, owing to their large specific surface area and adjustable network pore structure. The principle of electrospinning and key points relevant to its usage in the preparation of high‐performance electrochemical energy storage materials are reviewed herein based on recent publications, particularly focusing on research progress of relative materials. Also, this review describes a distinctive conclusion and perspective on the future challenges and opportunities in electrospun nanomaterials. 相似文献
370.
用从头算方法的MP2和CCSD(T)方法结合cc-pVTZ基组计算了二氯化锗同位素(70GeCl2、72GeCl2和76GeCl2)分子的平衡结构、光谱常数和非谐振力场.二氯化锗的几何结构、转动常数、振转相互作用常数、谐频、非谐振常数、四次和六次离心畸变常数、三次和四次力常数的计算结果与实验结果符合较好,二氯化锗分子的同位素效应较小,可能的原因是Ge同位素的质量变化相对较小.两种方法计算的结果均与实验结果符合,但CCSD(T)方法比MP2计算结果的偏差稍大一些,可能的原因是CCSD(T)方法在描述过共价Cl原子的电子相关时不够充分. 相似文献