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951.
Ying Chen Ping Xiang Gang Li Hui-Lan Chen Kandasamy Chinnakali Hoong-Kun Fun 《Supramolecular chemistry》2013,25(4):339-346
The crystal and molecular structures of alkylcobaloxime/ g -cyclodextrin ( g -CD) inclusion complexes: butyl(aqua)cobaloxime/ g -CD ( 1 ). hexyl(aqua)cobaloxime/ g -CD ( 2 ) and cyclohexyl(aqua)cobaloxime/ g -CD ( 3 ) were determined by X-ray diffraction analyses. Crystal data for 1 14H 2 O: P 2 1 2 1 2 1 , a =15.1335(3), b =18.9630(2), c =28.1545(5) Å, Z =4; 2 12H 2 O: P 2 1 2 1 2 1 , a =15.1135(4), b =19.1477(5), c =28.2715(7) Å, Z =4; 3 10H 2 O: P 2 1 2 1 2 1 , a =15.6898(2), b =16.9094(2), c =28.9762(2) Å, Z =4. The structural and conformational comparisons for the three g -CD inclusion complexes with their guest molecules as well as other CD inclusion analogs are discussed. 相似文献
952.
Yin Li Zsolt Csók László Kollár Koichi Iwata Erzsébet Szász 《Supramolecular chemistry》2013,25(6):374-378
2-Methylresorcinarene and its methylene-bridged cavitand derivative as host compounds were investigated in selective complexation of alkali metal ions as guests in methanol media by photoluminescence measurements. These host molecules possess either flexible (2-methylresorcinarene) or rigid (cavitand) molecular skeleton. The Benesi–Hildebrand method and the van't Hoff theory have been applied to determine the stability constants and the thermodynamic parameters, respectively. Considerable interactions between 2-methylresorcinarene and Li+ or Na+ ions have been observed while the rigid cavitand derivative can interact only with K+ or Cs+ ions. Neither the complexes of 2-methylresorcinarene with K+ or Cs+ nor those of the cavitand derivative with Li+ or Na+ ions are stable at room temperature in methanol media. Quantum-chemical investigations justified that only solvated Li+ and Na+ ions can form stable complexes with 2-methylresorcinarene while unsolvated K+ and Cs+ ions form stable complexes with the methylene-bridged cavitand. These results highlight that the stability of the guest solvation shell and its size could play a key role in the selectivity behaviour of host molecules. 相似文献
953.
Yi‐Ying Kao Chu‐Nian Cheng Sy‐Chyi Cheng Hsiu‐O Ho Jentaie Shiea 《Journal of mass spectrometry : JMS》2013,48(11):1129-1135
Electrospray laser desorption ionization mass spectrometry (ELDI/MS) was used to rapidly distinguish authentic banknotes from counterfeits of the US dollar and the New Taiwan dollar. The banknotes' surfaces were irradiated with a pulsed ultraviolet laser, after which the desorbed ink compounds entered an electrospray plume and formed ions via interactions with charged solvent species. Authentic banknotes were found to differ from their counterfeit equivalents in their surface chemical compositions. The detected chemical compounds included various polymers, plasticizers and inks; these results were comparable with those obtained using solvent extraction followed by electrospray ionization mass spectrometry analysis. Because of the high spatial resolution of the laser beam, ELDI/MS analysis resulted in minimal damage to the banknotes. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
954.
Chunxiao Lv Qing Li Yaowen Zhang Zhenyu Sui Bosai He Huarong Xu Yidi Yin Xiaohui Chen Kaishun Bi 《Journal of mass spectrometry : JMS》2013,48(8):904-913
A fast, sensitive and reliable ultra fast liquid chromatography‐tandem mass spectrometry (UFLC‐MS/MS) method has been developed and validated for simultaneous quantitation of polygalaxanthone III (POL), ginsenoside Rb1 (GRb1), ginsenoside Rd (GRd), ginsenoside Re (GRe), ginsenoside Rg1 (GRg1) and tumulosic acid (TUM) in rat plasma after oral administration of Kai‐Xin‐San, which plays an important role for the treatment of Alzheimer's disease (AD). The plasma samples were extracted by liquid–liquid extraction using ethyl acetate–isopropanol (1:1, v/v) with salidrdoside as internal standard (IS). Good chromatographic separation was achieved using gradient elution with the mobile phase consisting of methanol and 0.01% acetic acid in water. The tandem mass spectrometric detection was performed in multiple reaction monitoring mode on 4000Q UFLC‐MS/MS system with turbo ion spray source in a negative and positive switching ionization mode. The lower limits of quantification were 0.2–1.5 ng/ml for all the analytes. Both intra‐day and inter‐day precision and accuracy of analytes were well within acceptance criteria (±15%). The mean absolute extraction recoveries of analytes and IS from rat plasma were all more than 60.0%. The validated method has been successfully applied to comparing pharmacokinetic profiles of analytes in normal and AD rat plasma. The results indicated that no significant differences in pharmacokinetic parameters of GRe, GRg1 and TUM were observed between the two groups, while the absorption of POL and GRd in AD group were significantly higher than those in normal group; moreover, the GRb1 absorbed more rapidly in model group. The different characters of pharmacokinetics might be caused by pharmacological effects of the analytes. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
955.
Ying Su Christos S. Karamitros Julian Nomme Theresa McSorley Manfred Konrad Arnon Lavie 《Chemistry & biology》2013,20(4):533-540
Highlights? Increased expression of hASNase3 was observed in several tumors, but the relevance is unclear ? Cancer cells have increased glycolytic flux and thus have more glycine but less aspartate ? Glycine activates the asparaginase activity of hASNase3 by promoting self-cleavage ? Thus, glycine may act as a sensor that regulates cellular aspartate concentrations 相似文献
956.
Binbin Wei Qing Li Ronghua Fan Dan Su Xiuli Ou Kelin Chen Xiaohui Chen Ying Jia Kaishun Bi 《Journal of mass spectrometry : JMS》2013,48(4):448-458
Schisandra chinensis (Turcz.) Baill., a traditional Chinese medicine, has been clinically used for the treatment of insomnia for centuries. The insomnia mechanism and the possible active ingredients of S. chinensis remain largely unknown. The objective of this study was to develop a method to detect its components which could pass through the blood brain barrier (BBB) by determining the brain microdialysate and brain tissue homogenate samples and then obtain the pharmacokinetic profile in brain for comprehensive understanding of its hypnotic clinical efficacy. Therefore, an efficient, sensitive and selective ultra fast liquid chromatography/tandem mass spectrometry method for the simultaneous determination of six sedative and hypnotic lignans (schisandrin, schisandrol B, schisantherin A, deoxyshisandrin, γ‐schisandrin and gomisin N) of Schisandra chinensis (Turcz.) Baill. in rat brain tissue homogenate and brain microdialysates has been developed and validated. The analysis was performed on a Shim‐pack XR‐ODS column (75 mm × 3.0 mm, 2.2 µm) using gradient elution with the mobile phase consisting of acetonitrile and 0.1% formic acid water. The method was validated in brain homogenate and microdialysate samples, which all showed good linearity over a wide concentration range (r2 > 0.99), and the obtained lower limit of quantification was 0.1 ng · ml?1 for the analytes in brain microdialysate samples. The intra‐ and inter‐day assay variability was less than 15% for all analytes. The study proved the six lignans, as sedative and hypnotic ingredients, could pass through the BBB with brain targeting, distributed mainly in the hypothalamus and possessed complete pharmacokinetics process in brain. The results also indicated that significant difference in pharmacokinetic parameters of the analytes was observed between two groups, while absorptions of these analytes in insomniac group were significantly better than those in normal group. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
957.
A novel flame retardant (PSiN), containing silicon and nitrogen, was synthesized using N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane (KH-602) and diphenylsilanediol through solution polycondesation and it was used together with potassium-4-(phenylsulfonyl)benzenesulfonate (KSS) to prepare a flame-retardant system for polycarbonate (PC). The structure and thermal property of PSiN were characterized by Fourier transform infrared spectroscopy (FTIR), 1HNMR and thermogravimetric analysis (TG) tests. Flammability and thermal behaviors of PC/KSS/PSiN systems were estimated by limited oxygen index (LOI), cone calorimeter, vertical burning test (UL-94), and TG tests. The results showed that the flame retardancy and char residues of PC/KSS system were improved with the addition of PSiN. When 1 mass% PSiN and 0.5 mass% KSS were incorporated, the LOI value of PC was found to be 46, and class V-0 of the UL-94 test. Moreover, both the heat release rate and the total heat release of PC/KSS/1 mass% PSiN decreased compared with those of PC and PC/KSS systems. The microstructures observed by scanning electron microscopy and FTIR indicated that the surface of the char for PC/KSS/PSiN system hold a more cohesive and denser char structure when compared with the pure PC and PC/KSS system. 相似文献
958.
Effects of common synergistic agents on intumescent flame retardant polypropylene with a novel charring agent 总被引:1,自引:0,他引:1
In this article, the laboratory-made poly (p-ethylene terephthalamide) (PETA) was used as a novel charring agent and it combined with ammonium polyphosphate (APP) to prepare the intumescent flame retardant (IFR). For improving the flame-retardant efficiency of IFRs on polypropylene (PP), several general synergistic agents, such as common zinc oxide (Com-ZnO), nanometer structural zinc oxide (Nano-ZnO), zeolite 4A, and aluminum hypophosphite(Al(H2PO2)3), were added in composites of PP/IFR, and the synergistic effect was investigated by the limited oxygen index (LOI), the UL-94 (vertical flame) test, thermogravimetric analysis (TG), thermogravimetry-fourier transform infraredspectroscopy (TG-IR) test, and scanning electron microscopy (SEM). It indicated that the flame retardancy was significantly enhanced in terms of prompting the char formation of PETA and interaction between APP and synergistic agents. Overall, Al(H2PO2)3 was the most effective synergistic agent among them. TG-IR analysis showed that the addition of Al(H2PO2)3 could delay the release of NH3, and make the release of NH3 more smooth, which was useful to form a dense char. SEM presented that compact, continuous and good intumescent charring layers were observed in all PP/IFR systems with synergistic agent. 相似文献
959.
Gaonan Li Tongtong Li Ying Deng Yong Cheng Fan Shi Wei Sun Zhenfan Sun 《Journal of Solid State Electrochemistry》2013,17(8):2333-2340
In this paper, a carbon ionic liquid electrode (CILE) was fabricated using ionic liquid 1-hexylpyridinium hexafluorophosphate as modifier, which was further in situ electrodeposited with graphene (GR) and gold nanoparticles step by step to get an Au/GR nanocomposite modified CILE. Myoglobin (Mb) was further immobilized on the Au/GR/CILE surface with Nafion film to get the modified electrode denoted as Nafion/Mb/Au/GR/CILE. Cyclic voltammetric experiments indicated that a pair of well-defined quasi-reversible redox peaks appeared in pH 3.0 phosphate buffer solution with the formal potential (E 0′) located at ?0.197 V (vs. saturated calomel electrode), which was the typical characteristics of Mb heme Fe(III)/Fe(II) redox couples. Thus, the direct electron transfer rate between Mb and the modified electrode was promoted due to the high conductivity and increased surface area of Au/GR nanocomposite present on electrode surface. Based on the cyclic voltammetric data, the electrochemical parameters of Mb on the modified electrode were calculated. The Mb-modified electrode showed excellent electrocatalytic activities towards the reduction of trichloroacetic acid and H2O2 with wider linear range and lower detection limit. Using GR and Au nanoparticles modified CILE, a new third-generation electrochemical Mb biosensor was constructed with good stability and reproducibility. 相似文献
960.
Pengjian Zuo Tao Wang Guangyu Cheng Chunyu Du Yulin Ma Xinqun Cheng Geping Yin 《Journal of Solid State Electrochemistry》2013,17(7):1955-1959
Li2FeSiO4/C cathode materials have been prepared using the conventional solid-state method by varying the sintering temperature (650 °C, 700 °C and 750 °C), and the structure and electrochemical performance of Li2FeSiO4/C materials are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), galvanostatic charge–discharge tests, respectively. The results show that Li2FeSiO4 nano-crystals with a diameter of about 6–8 nm are inbedded in the amorphous carbon, and the Li2FeSiO4/C material obtained at 700 °C exhibits an initial discharge capacity of 195 mA?h g?1 at 1/16 C in the potential range of 1.5–4.8 V. The excellent electrochemical performance of Li2FeSiO4/C attributes to the improvement of conductivity and reduction of impurity by the optimization of the sintering temperature. 相似文献