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Liu J.Y.,South China University of Technology | Reni L.,South China University of Technology | Wei Q.,China National Analytical Center | Wu J.L.,South China University of Technology | And 3 more authors.
Express Polymer Letters

Polycaprolactone (PCL)/calcium sulfate (CS) whisker composites have been fabricated by melt blending and coprecipitation methods respectively. Scanning electron microscope (SEM) was used to observe the microstructure of the composites. The crystallization and thermal properties were characterized by polarized optical microscope (POM), X-ray diffractometry (XRD), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). For composites prepared by melt blending method, experiment results show that average length of the whiskers is shortened. The crystallization perfection of PCL in composites is improved by adding whiskers. The flexural strength increases whereas the impact strength decreases. For composites prepared by coprecipitation method, whisker addition worsens the crystallization perfection of PCL. An improvement of 21% in flexural strength and 22% in impact strength has been achieved for the composite with 15 wt% of whiskers. © BME-PT. Source

Chen Z.,China National Analytical Center | Cao R.,Sun Yat Sen University | Shi B.,Sun Yat Sen University | Guo L.,Xinjiang Huashidan Pharmaceutical Co. | And 4 more authors.
European Journal of Medicinal Chemistry

A series of novel 1,9-disubstituted β-carbolines was designed, synthesized and evaluated as cytotoxic and DNA intercalating agents. Compounds 7b, 7c, 8b and 8c exhibited the most potent cytotoxic activities with IC 50 values of lower than 20 μM against ten human tumor cell lines. The results indicated that (1) the 3-chlorobenzyl and 3-phenylpropyl substituents in position-9 of β-carboline nucleus were the suitable pharmacophoric group giving rise to significant antitumor agents; (2) the length of the alkylamino side chain moiety affected their cytotoxic potencies, and three CH 2 units were more favorable. In addition, these compounds were found to exhibit remarkable DNA intercalating effects. © 2011 Elsevier Masson SAS. All rights reserved. Source

Xu Z.-L.,South China Agricultural University | Deng H.,South China Agricultural University | Deng X.-F.,South China Agricultural University | Yang J.-Y.,South China Agricultural University | And 7 more authors.
Food Chemistry

A multi-analytes method for monitoring of organophosphorus pesticides (OPs) using a combination of broad-specificity direct competitive enzyme-linked immunosorbent assay (dcELISA) and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. The reaction formats of dcELISA as well as the matrix effects of vegetable samples by different treatments were studied. The dcELSIA based on horseradish peroxidase-labelled monoclonal antibody and solid-phase extraction can analyse 42 samples in duplicate simultaneously for 12 OPs with a limit of detection at 20 μg L-1 within 40 min, with good accuracy and reproducibility. For screening purpose, the dcELISA can distinguish positive samples from hundreds of negative samples at a rapid, high-throughput and low cost manner. The positive samples can be following confirmed by HPLC-MS/MS for the kinds and the relative amounts of OPs. The method is suitable for monitoring of OP contamination in vegetables samples with high-efficiency and low cost. © 2011 Elsevier Ltd. All rights reserved. Source

Li N.,Chengdu University of Technology | Ni S.,China National Analytical Center

The use of noble metal nanoparticles (NPs) as reductants in chemiluminescence (CL) has been reported only rarely owing to their high oxidation potentials. Interestingly, nucleophiles could dramatically lower the oxidation potential of Ag NPs, such that in the presence of nucleophiles Ag NPS could be used as reductants to induce the CL emission of luminol, an important CL reagent widely used in forensic analysis for the detection of trace amounts of blood. Although nucleophiles are indispensible in Ag NP-luminol CL, only inorganic nucleophiles such as Cl-, Br-, I- and S2O3 2- have been shown to be efficient. The effects of organic nucleophiles on CL remain unexplored. In this study, 20 standard amino acids were evaluated as novel organic nucleophiles in Ag NP-luminol CL. Histidine, lysine and arginine could initiate CL emission; the others could not. It is proposed that the different behaviors of 20 standard amino acids in the CL reactions derive from the interface chemistry between Ag NPs and these amino acids. UV/vis absorption spectra were studied to validate the interface chemistry. In addition, imidazole and histidine were chosen as a model pair to compare the behavior of the monodentate nucleophile with that of the corresponding multidentate nucleophile in Ag NP-luminol CL. Copyright © 2014 John Wiley & Sons, Ltd. Source

Ma M.-Y.,China National Analytical Center | Su L.-K.,China National Analytical Center
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis

The samples were decomposed with HNO3+HCl, and Fe3+-citric acid mix solution was added to eliminate interferences. The elimination and mechanism of tellurium interference with selenium determination by HG-AFS were studied, and the residuary influence of NO3- and NO2- was investigated. The interference of ferric trichloride, hydrochloric acid, citric acid and PBH concentration with the fluorescence intensity of selenium was observed by the orthogonal test design combined with the mono-factor test. The detection limit was 0.15μg · L-1. The relative standard deviation of a solution containing 27.01μg · L-1 selenium in sample was in the range of 3.1%~4.2% (n=11), and the recoveries of selenium were 96.1%~102.3%. The results obtained were satisfied, and the method was successfully applied to the determination of selenium in high purity tellurium samples. Source

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