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101.
Jie Han Feng-Yan Zhang Juan-Yu Wang Yan-Mei Wang Mei-Li Pang Ji-Ben Meng 《Liquid crystals》2013,40(8):825-833
A series of heterocyclic liquid crystalline compounds containing 1,3,4-oxadiazole/thiadiazole, furan and thiophene units were synthesised and characterised by means of electrospray ionisation-mass spectrometry (ESI-MS), high-resolution mass spectroscopy (HRMS), 1H nuclear magnetic resonance (NMR) and 13C NMR. The thermal behaviours were investigated by differential scanning calorimetry (DSC) and polarised optical microscopy (POM). The effect of the 1,3,4-oxadiazole, 1,3,4-thiadiazole, furan, thiophene and benzene rings on the liquid crystalline properties was discussed briefly in context with the geometrical and electronic factors. The results showed that the tendency to form mesophases follows the sequence: 1,4-disustituted benzene >2,5-disubstituted thiophene >2,5-disustituted furan and 1,3,4-thiadiazole >1,3,4-oxadiazole. 相似文献
102.
Jie Han Feng‐Yan Zhang Zhi Chen Juan‐Yu Wang Li‐Rong Zhu Mei‐Li Pang 《Liquid crystals》2013,40(12):1359-1365
A series of new compounds based on aromatically 2,5‐disubstituted 1,3,4‐oxadiazoles without flexible chains, formulated as p‐R–C6H4–(OC2N2)–(p‐C6H4)2–R′ with (i) R = CH3O, R′ = CH3O, CH3S, F, H (Ia–Id), (ii) R = CH3S, R′ = CH3O, CH3S, F, H (IIa–IId) and (iii) R = F, R′ = CH3O, CH3S, F, H (IIIa–IIId) (p‐C6H4 and OC2N2 represent a p‐phenylene spacer and a 1,3,4‐oxadiazole ring, respectively), were synthesised and characterised by 1H and 13C NMR, MS and HRMS techniques. Mesomorphic properties were investigated using differential scanning calorimetry and polarizing optical microscopy. All of the target compounds (except Id, IId, IIIc and IIId) exhibited an enantiotropic nematic mesophase with high melting temperatures. The liquid crystalline properties of these compounds were influenced greatly by polarity, steric factors and positions of the terminal groups. The effect of the terminal groups on the liquid crystal properties is discussed. 相似文献
103.
荧光增白剂28(F-28)为欧盟标准EN 648-2006《与食品接触的纸和纸板-荧光增白剂牢度的测定》中判断食品接触材料所含荧光增白剂是否向食品中迁移的标样。我们发现,在规定的波长365nm紫外光激发下,F-28所制成的标样会出现光漂白现象。因此,本文对F-28的光漂白特性进行研究。结果表明,紫外辐照时间为60s时,四级(3mg/L)、三级(8mg/L)、二级(31mg/L)、一级(125mg/L)滤纸和玻纤的最大荧光值衰减率分别为0.16%、0.29%、0.92%、0.44%和2.59%、1.99%、0.49%、3.14%;当辐照时间延长到1800 s时,最大荧光值衰减率分别增加为4.67%、4.22%、5.51%、2.75%和35.37%、39.78%、28.09%、39.38%。因此,在对食品接触材料是否含有荧光增白剂以及是否迁移的测试中,必须考虑光漂白因素。同时,滤纸作为迁移实验载体,在降低光漂白和稳定性方面比玻纤更具优势。 相似文献
104.
Longguang Yang Yunfei Li Qian Chen Jianfeng Zhao Changsheng Cao Yanhui Shi Guangsheng Pang 《Transition Metal Chemistry》2013,38(4):367-375
The synthesis of a series of chiral Pd(L)PyBr2 (3a–3e) and Pd(L)PyCl2 (4d and 4e) complexes from l-phenylalanine is presented (L = (S)-3-allyl-4-benzyl-1-(2,6-diisopropylphenyl)-imidazolin-2-ylidene (a), (S)-4-benzyl-1-(2,6-diisopropylphenyl)-3-(naphthalen-2-ylmethyl)imidazolin-2-ylidene (b), (S)-4-benzyl-3-(biphenyl-4-ylmethyl)-1-(2,6-diisopropylphenyl)imidazolin-2-ylidene (c), (S)-4-benzyl-1-(2,6-diisopropylphenyl)-3-(naphthalen-1-ylmethyl)imidazolin-2-ylidene (d) or (S)-4-benzyl-1-(2,6-diisopropylphenyl)-3-(2,4,6-trimethylbenzyl)imidazolin-2-ylidene (e). The complexes were characterized by physicochemical and spectroscopic methods, and the X-ray crystal structures of 3a–3c and 4d are reported. In each case, there is a slightly distorted square-planar geometry around palladium, which is surrounded by imidazolylidene, two trans halide ligands and a pyridine ligand. There are π–π stacking interactions in the crystal structures of these complexes. Complex 3a showed good catalytic activity in the Cu-free Sonogashira coupling reaction under aerobic conditions. 相似文献
105.
Hui Chen Chun-lin Fan Zhi-bin Wang Qiao-ying Chang Wei Wang Xiao-ying Li Guo-fang Pang 《Accreditation and quality assurance》2013,18(4):351-358
In this study, the method for determining the stable carbon isotope ratio value was validated. Measurement uncertainty of stable carbon isotope ratio value of whole honey and its extracted protein derived from repeatability, reference gas, reference standards and calibration curve was calculated by applying the “bottom-up” approach according to Eurachem/CITAC guide. The expanded uncertainties for all results ranged from 0.14 to 0.19 ‰, with most of them between 0.15 and 0.16 ‰ (the coverage factor k = 2, the level of confidence p is approximately 95 %). The percentage contribution of each source to the relative combined uncertainty was calculated. The data indicated that calibration curves have more contribution to the relative combined uncertainty than repeatability and reference standards. On the other hand, the measurement uncertainty of C-4 sugar content in honey was estimated. Based on these results, 58 honey samples, such as acacia, chaste, Northeast China black bee, flowers and jujube honey, have been gathered to determine the C-4 plant sugar content adulteration in honey by elemental analyzer with an isotope ratio mass spectrometer. It can be found that all honey samples were not adulterated by C-4 plant sugar. 相似文献
106.
聚芳醚酮树脂的分子设计与合成及性能 总被引:1,自引:0,他引:1
聚芳醚酮树脂是20世纪发展起来的重要特种工程塑料.因其优良的耐热、耐腐蚀、耐摩擦及生物相容性好等特点,在国防军工、武器装备、航空航天、电子、汽车、机械、石油工业、核能及理疗卫生等高技术领有广泛的应用.此类材料大都采用双酚单体和双氟单体通过A2+B2型亲核缩聚反应制备.这类聚合物的分子结构对材料的性能影响较大,一般情况下分子链由醚、酮、苯三元规整结构构成时,聚合物为半结晶态;然而,当分子结构中存在侧基或其他非规整结构往往破坏聚合物的结晶结构,聚合物呈现无定型态.半结晶聚芳醚酮聚合物具有非常优异的耐热、耐化学稳定性一般作为结构型材料使用;无定型聚芳醚酮具有良好的加工性能,并且可进行一些功能化成为一类优异的功能型材料.本文从结构与性能关系出发,介绍了聚芳醚酮树脂种类,聚芳醚酮树脂的发展历程及合成方法;探讨了聚芳醚酮材料结构与性能关系;总结了功能性聚芳醚酮材料的前沿进展;最后结合实际展望了聚芳醚酮的应用发展方向. 相似文献
107.
Wen Zhou Xiao-Li Sun Lin Gu Fei-Fei Bao Xin-Xin Xu Chun-Yan Pang Zhi-Guo Gu Zaijun Li 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(2):843-852
Three new mesoporous silica materials IL15SGs (HF15SG, TF15SG and DF15SG) doped with benzo-15-crown-5 and imidazolium based ionic liquids (C8mim+PF6 ?, C8mim+BF4 ? or C8mim+NTf 2 ? ) have been prepared by a simple approach to separating lithium isotopes. The formed mesoporous structures of silica gels have been confirmed by transmission electron microscopy image and N2 gas adsorption–desorption isotherm. Imidazolium ionic liquids acted as templates to prepare mesoporous materials, additives to stabilize extractant within silica gel, and synergetic agents to separate the lithium isotopes. Factors such as lithium salt concentration, initial pH, counter anion of lithium salt, extraction time, and temperature on the lithium isotopes separation were examined. Under optimized conditions, the extraction efficiency of HF15SG, TF15SG and DF15SG were found to be 11.43, 10.59 and 13.07 %, respectively. The heavier isotope 7Li was concentrated in the solution phase while the lighter isotope 6Li was enriched in the gel phase. The solid–liquid extraction maximum single-stage isotopes separation factor of 6Li–7Li in the solid–liquid extraction was up to 1.046 ± 0.002. X-ray crystal structure analysis indicated that the lithium salt was extracted into the solid phase with crown ether forming [(Li0.5)2(B15)2(H2O)]+ complexes. IL15SGs were also easily regenerated by stripping with 20 mmol L?1 HCl and reused in the consecutive removal of lithium ion in five cycles. 相似文献
108.
Ariane Wohlfarth Adarsh S. Gandhi Shaokun Pang Mingshe Zhu Karl B. Scheidweiler Marilyn A. Huestis 《Analytical and bioanalytical chemistry》2014,406(6):1763-1780
Background
PB-22 (1-pentyl-8-quinolinyl ester-1H-indole-3-carboxylic acid) and 5F-PB-22 (1-(5-fluoropentyl)-8-quinolinyl ester-1H-indole-3-carboxylic acid) are new synthetic cannabinoids with a quinoline substructure and the first marketed substances with an ester bond linkage. No human metabolism data are currently available, making it difficult to document PB-22 and 5F-PB-22 intake from urine analysis, and complicating assessment of the drugs’ pharmacodynamic and toxicological properties.Methods
We incubated 10 μmol/l PB-22 and 5F-PB-22 with pooled cryopreserved human hepatocytes up to 3 h and analyzed samples on a TripleTOF 5600+ high-resolution mass spectrometer. Data were acquired via TOF scan, followed by information-dependent acquisition triggered product ion scans with mass defect filtering (MDF). The accurate mass full scan MS and MS/MS metabolite datasets were analyzed with multiple data processing techniques, including MDF, neutral loss and product ion filtering.Results
The predominant metabolic pathway for PB-22 and 5F-PB-22 was ester hydrolysis yielding a wide variety of (5-fluoro)pentylindole-3-carboxylic acid metabolites. Twenty metabolites for PB-22 and 22 metabolites for 5F-PB-22 were identified, with the majority generated by oxidation with or without glucuronidation. For 5F-PB-22, oxidative defluorination occurred forming PB-22 metabolites. Both compounds underwent epoxide formation followed by internal hydrolysis and also produced a cysteine conjugate.Conclusion
Human hepatic metabolic profiles were generated for PB-22 and 5F-PB-22. Pentylindole-3-carboxylic acid, hydroxypentyl-PB-22 and PB-22 pentanoic acid for PB-22, and 5′-fluoropentylindole-3-carboxylic acid, PB-22 pentanoic acid and the hydroxy-5F-PB-22 metabolite with oxidation at the quinoline system for 5F-PB-22 are likely the best targets to incorporate into analytical methods for urine to document PB-22 and 5F-PB-22 intake.Metabolism of synthetic cannabinoids PB-22 and 5F-PB-22 by human hepatocyte incubation and high-resolution mass spectrometry 相似文献
109.
Lihong Lin Wei Yu Yanan Pang Changsong Sun Qinghe Meng Xiaolei Li Xingjie Guo 《Analytical and bioanalytical chemistry》2014,406(22):5521-5526
A simple, sensitive, and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for determination of pyraoxystrobin in rat plasma and applied to a toxicokinetics study. The separation was performed by gradient elution on a Luna 5 μ C18 (2) 100 Å column (50?×?4.6 mm I.D., 5 μm) with mobile phase: water (0.1 % formic acid, v/v)/acetonitrile (0.1 % formic acid, v/v), followed by quantification with a mass detector in multiple reaction monitoring (MRM) mode using ESI as an interface. The calibration curve was linear over a concentration range of 1.00–200 ng/mL. The recovery for pyraoxystrobin ranged from 101.4 to 108.2 %. The intraday bias and precision ranged from ?9.3 to 8.1 % and from 0.7 to 8.4 %, respectively, and the interday bias and precision ranged from ?0.3 to 4.0 % and from 4.4 to 7.2 %, respectively. The toxicokinetics of pyraoxystrobin after single 100 and 1,000 mg/kg oral doses were studied in rats. Figure
The chromatogram of pyraoxystrobin highest calibration standard (ULOQ) extract. 相似文献
110.
运用分子动力学模拟,研究了腺苷酸(激动剂)与A2AAR腺苷受体蛋白的相互作用和配体结合诱导的蛋白动力学变化.识别了与腺苷酸结合力强于0.5kcal/mol的关键基团:A63^2.61,I66^2.64,V84^3.32,L85^3.33,T88^3.36,F168^5.29,M177^5.38,L249^6.51,H250^6.52和N253^6.55,观察到腺苷酸没有与L167^5.28相互作用,这一结果支持了L167^5.28是抑制剂特异性结合位点,不与激动剂结合.未结合配体(激动剂或抑制剂)的单体A2AAR和腺苷酸结合后的A2AAR在构象上有三个不同功能性开关.腺苷酸结合可以诱导A2AAR腺苷受体蛋白的构象调整,使得三个功能性开关器件的构象与单体A2AAR不同. 相似文献