China National Analytical Center
China National Analytical Center
Cao G.S.,Sun Yat Sen University |
Rong M.Z.,Sun Yat Sen University |
Zhang M.Q.,Sun Yat Sen University |
Ye X.J.,China National Analytical Center
RSC Advances | Year: 2016
Herein, to prepare an extrinsic self-healing system with high heat resistance to tolerate the processing of thermoplastics, a group of new healants based on atom transfer radical polymerization is developed. It consists of microencapsulated acrylate monomers (2-methyl-2-adamantylmethacrylate or trimethylolpropane trimethacrylate), macroinitiator poly(methyl methacrylate)-Br, and supported catalyst (coordination compound of cyclic 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane and cuprous bromide). Composites containing the healing agent with polystyrene, poly(methyl methacrylate) and acrylonitrile-butadiene-styrene copolymer as matrices were successfully manufactured by compression molding. Impact tests indicate that the composites can regain their mechanical strength as a result of polymerization of the released acrylate monomers at room temperature. The strong interaction between the cyclic ligand and CuBr obviously enhances the thermostability of the ligand and depresses the negative influence of cupric ions on the aging properties of the matrix polymers. The present work offers a new route for the design and application of self-healing thermoplastics. © 2016 The Royal Society of Chemistry.
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 | Year: 2011
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.
Zhu Y.,Sun Yat Sen University |
Ye X.J.,Sun Yat Sen University |
Ye X.J.,China National Analytical Center |
Rong M.Z.,Sun Yat Sen University |
Zhang M.Q.,Sun Yat Sen University
Composites Science and Technology | Year: 2016
To improve flowability of the healing agent released from micropipelines without manual intervention, this work prepared a proof-of-concept self-healing glass fiber/epoxy composite, in which plastic (polypropylene (PP)) tubes were embedded and used as containers of epoxy/mercaptan healing agent and foaming agent. Decomposition of the foaming agent at 70 °C created inflated gas in the sealed PP tubes in advance, which increased the internal pressure. Upon damage of the composite, the pressurized healing fluid burst out covering larger cracked plane and enhanced mixing of the liberated epoxy monomer and hardener. As a result, higher healing efficiency was observed as compared to the case without pressurization. The factors that influence healing performance of the system (e.g., tube spacing, content of the foaming agent, foaming time, etc.) were discussed in detail. The proposed approach is believed to have adequate expansibility and can be applied in other self-healing composites with micropipelines. © 2016 Elsevier Ltd
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 | Year: 2012
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.
Li N.,Chengdu University of Technology |
Ni S.,China National Analytical Center
Luminescence | Year: 2014
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.
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 | Year: 2011
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.
Deng J.,China National Analytical Center |
Fan C.,Jinan University |
Jiang Z.,Jinan University |
Ye W.,Jinan University |
Yang Y.,China National Analytical Center
Analytical Methods | Year: 2012
A novel fingerprinting approach for quality assessment and origin tracing of Guangdong Liangcha granules (GLG) by electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) has been established. A negative-ion ESI-TOF spectrum gave the best chemical information and was most suitable to construct the chemical profile fingerprinting of GLG. Using high-resolution TOF-MS, 61 common mass spectral peaks based on the major constituents present in GLG were accurately and simultaneously detected without any chromatographic separation, providing valuable information for overall assessment of the quality and differentiation of the origin of the preparation. Six sources of commercial GLG products produced by five different manufacturers have been successfully differentiated, according to the principal component analysis of 61 common mass spectral peaks, and the stability of them was also assessed. The results of our experimental data demonstrated that ESI-TOF-MS fingerprinting is a useful tool for rapid pharmaceutical analysis, with promising prospects for overall quality assessment and origin differentiation of commercial pharmaceutical products. © 2012 The Royal Society of Chemistry.
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 | Year: 2011
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.
Yang Y.,China National Analytical Center |
Guo P.,China National Analytical Center |
Zhang Q.,China National Analytical Center |
Li D.,China National Analytical Center |
And 2 more authors.
Science of the Total Environment | Year: 2010
Air samples were collected weekly at an urban site and a suburban site in Guangzhou City, China, from April 2005 to March 2006, to measure the concentrations of polycyclic aromatic hydrocarbons (PAHs) in the ambient air and study their seasonal variations, gas/particle partitioning, origins and sources. The concentrations of ∑16-PAHs (particle+gas) were 129.9±73.1ngm-3 at the urban site and 120.4±48.5ngm-3 at the suburban site, respectively. It was found that there was no significant difference in PAH concentrations between the urban and suburban sites. Seasonal variations of PAH concentrations at the two sampling sites were similar, with higher levels in the winter that gradually decreased to the lowest levels in the summer. The average concentrations of ∑16-PAHs in the winter samples were approximately three times higher than those of the summer samples because in the summer local emissions dominated, and in the winter the contribution from outside sources or transported PAHs is increased. The plot of logKp versus logPL 0 for the data sets of summer and winter season samples had significantly different slopes at both sampling sites. The slopes for the winter samples were steeper than those for the summer samples. It was also observed that gas/particle partitioning of PAHs showed different characteristics depending on air parcel trajectories. Steeper slopes were obtained for an air parcel that traveled across the continent to the sampling site from the northern or northeastern sector, whereas shallower slopes were obtained for air masses that traveled across the sea from the southern or eastern sector. Diagnostic ratio analytical results imply that the origins of PAHs were mainly from petroleum combustion and coal/biomass burning. The anthracene/phenanthrene and benzo[a]anthracene/chrysene ratios in the winter were significantly lower than those in the summer, which indicate that there might be long-range transported PAH input to Guangzhou in the winter. © 2010 Elsevier B.V.
Nong Y.-J.,China National Analytical Center |
Xie J.-D.,China National Analytical Center |
Huang M.-H.,China National Analytical Center |
Guo P.-R.,China National Analytical Center |
And 2 more authors.
Journal of Chinese Mass Spectrometry Society | Year: 2016
According to determination of available forms of lead and cadmium in soil, the contents of lead and cadmium were directly determined with DTPA as extracted by inductively coupled plasma-mass spectrometry (ICP-MS). The effects of ultrasonic extraction time, dilution time of extraction agent and the analytical conditions were investigated, and the elimination of matrix interference was compared. The results show that the available lead and cadmium have good linearity in the concentrations of 1-200 μg/L, and the detection limits of the method are 0.019 mg/kg and 0.0014 mg/kg, respectively, the relative standard deviation is less than 6%. The accuracy and precision of the method were verified by analyzing national standard reference materials. There was no significant difference between this method and the national standard method (GB/T 23739-2009) by t test, the relative standard deviation is less than 5%. This method has characteristics of convenient, low detection limit, high accuracy and good precision, which can be applied to determine available forms of lead and cadmium in large batches agricultural pollution soil. © 2016, Editorial Board of Journal of Chinese Mass Spectrometry Society. All right reserved.