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941.
QING XiangDong WU HaiLong NIE ChongChong LI Yong YAN XiuFang ZHANG XiHua YIN XiaoLi YU RuQin 《中国科学:化学(英文版)》2013,56(11):1641-1650
This work presents a novel application of second-order calibration based on self-weighted alternating trilinear decomposition(SWATLD)algorithm for analyzing the HPLC-DAD data.The proposed method makes it possible to simultaneously determine teflubenzuron,hexaflumuron,flufenoxuron,chlorfluazuron,diflubenzuron and benzoylurea in different fruit samples,i.e.pear,apple and banana,in the selected time region of chromatogram.The concentration,elution time and spectral information of these benzoylurea insecticides are selectively extracted from complex matrices even in the presence of unknown interferences.The root-mean-square error of prediction(RMSEP)and figures of merit,including sensitivity(SEN),selectivity(SEL)and limit of detection(LOD)are employed to access the performance of the method.The LODs obtained for these insecticides are within the range 0.017–0.26 ppm in pears,0.039–0.33 ppm in apples,0.041–0.44 ppm in bananas,respectively.Such a chemometrics-based protocol holds great potential to be extended as a promising alternative for more practical applications in food safety and quality monitoring. 相似文献
942.
LIU ZhiTian HU SuJun ZHANG LinHua CHEN JunWu PENG JunBiao CAO Yong 《中国科学:化学(英文版)》2013,56(8):1129-1136
A new silole monomer with two 4-(N,N-dimethylamino)phenyl substitutions on silicon atom as designed and synthesized.Three copolymers PF-N-HPS1,PF-N-HPS10 and PF-N-HPS20 were then obtained by copolymerizations of 2,7-fluorene derivatives with the silole monomer at feed ratios of 1%,10%,and 20%.Their UV-vis absorption,electrochemical,photoluminescent,and electroluminescent (EL) properties were investigated.PF-N-HPS possessed HOMO levels of 5.25-5.58 eV,and showed green emissions.Using PF-N-HPS as the emissive layer,three different polymer light-emitting diodes were fabricated as device A with ITO/PEDOT/PF-N-HPS/Al,device B with ITO/PEDOT/PF-N-HPS/Ba/Al,and device C with ITO/PEDOT/PF-N-HPS/TPBI/Ba/Al.For the device A,PF-N-HPS only showed very low EL efficiency of 0.06-0.33 cd/A,indicating that the Al cathode could not inject electron efficiently to the emissive polymers containing the 4-(N,N-dimethylamino)phenyl groups.For the device B,low work function Ba supplied better electron injections,and the EL efficiency could be improved to 0.85-1.44 cd/A.TPBI with a deep HOMO level of 6.2 eV could enhance electron transport and hole blocking.Thus modified recombinations and largely elevated EL efficiency of 4.56-7.96 cd/A were achieved for the device C.The separation of the emissive layer and metal cathode with the TPBI layer may also suppress exciton quenching at the cathode interface. 相似文献
943.
Herein, we present three imidazo[1,2‐a]pyridin‐2(3 H)‐one derivatives that are diamagnetic in solution, but paramagnetic in the solid state, possibly owing to a stacking‐induced formation of phenoxide‐type radicals. Notably, a larger bathochromic shift of the absorption (even up to the near‐ infrared region) of these three compounds was observed in the solid state than in solution, which was attributable to the ordered columnar stacking arrangements or their single‐electron character as radicals in the solid state. Interestingly, compared to that in solution, (E)‐3‐(pyridin‐4′‐ylmethylene)imidazo[1,2‐a]pyridine 2(3 H)‐one displayed a largely red‐shifted emission (centered at 660 nm, with tailing above 800 nm) in the solid state. A larger bathochromic shift (260 nm) of the emission is an indication of better order and tight stacking in the solid state, which is brought about by the rigid and polar acceptor. These three compounds also reveal different magnetic susceptibilities at 300 K, thus implying that they possess various columnar stacking structures. Most interestingly, these three radicals exhibit unusual ferromagnetic‐to‐antiferromagnetic phase transitions, which can be attributed to anisotropic contraction and non‐uniform slippage of the columnar stacking chains. 相似文献
944.
Rui Feng Yong Zhang He Li Dan Wu Xiaodong Xin Sen Zhang Haiqin Yu Qin Wei Bin Du 《Analytica chimica acta》2013
Nano-montmorillonites belong to aluminosilicate clay minerals with innocuity, high specific surface area, ion exchange, and favorable adsorption property. Due to the excellent properties, montmorillonites can be used as labels for the electrochemical immunosensors. In this study, nano-montmorillonites were converted to sodium montmorillonites (Na-Mont) and further utilized for the immobilization of thionine (TH), horseradish peroxidase (HRP) and the secondary anti-zeranol antibody (Ab2). The modified particles, Na-Mont-TH-HRP-Ab2 were used as labels for immunosensors to detect zeranol. This protocol was used to prepare the immunosensor with the primary antibody (Ab1) immobilized onto the nanoporous gold films (NPG) modified glassy carbon electrode (GCE) surface. Within zeranol concentration range (0.01–12 ng mL−1), a linear calibration plot (Y = 0.4326 + 8.713 X, r = 0.9996) was obtained with a detection limit of 3 pg mL−1 under optimal conditions. The proposed immunosensor showed good reproducibility, selectivity, and stability. This new type of immunosensors with montmorillonites and NPG as labels may provide potential applications for the detection of zeranol. 相似文献
945.
946.
A new ent-kaurane diterpenoid from Rubus corchorifolius 总被引:1,自引:0,他引:1
Yang-Wen Ou Xue-Xiang Chen Min Zhang Xiao-Juan Liu Yong Cao 《Chemistry of Natural Compounds》2013,48(6):999-1001
947.
The intermolecular hydrogen bonds of mono‐ and dihydrated complexes of 7‐(3′‐Pyridyl)indole (7‐3′PI) have been investigated using the time‐dependent density functional theory (TD‐DFT) method. The electrostatic potential analysis of monomer 7‐3′PI and 7‐(3′‐Pyridyl)indole‐water (7‐3′PI‐W) indicates that an intermolecular hydrogen bond between two waters can be formed for 7‐(3′‐Pyridyl)indole‐2water (7‐3′PI‐2W) complex. The calculated bond lengths of the intermolecular hydrogen bonds of 7‐3′PI‐W and 7‐3′PI‐2W in the S1 state (the first excited singlet state) are all shortened compared to the ground state. By the analysis of bond length, charge population and infrared spectra, it is demonstrated that the intermolecular hydrogen bonds of 7‐3′PI‐W and 7‐3′PI‐2W are all strengthened upon electronic excitation to the S1 state. Moreover, the fluorescence of 7‐3′PI‐W and 7‐3′PI‐2W are all red‐shifted to larger wavelength compared to monomer 7‐3′PI. The red‐shift of fluorescence peak of 7‐3′PI‐W and 7‐3′PI‐2W should be attributed to the change of hydrogen bond interaction before and after photoexcitation. Therefore, it can be concluded that the intermolecular hydrogen bonding strengthening in the excited S1 state induces the fluorescence weakening of 7‐3′PI. 相似文献
948.
Strobilurins have become one of the most important classes of agricultural fungicides. To search for new strobilurin derivatives with high activity against resistant pathogens, a series of new β‐methoxyacrylate analogues containing substituted pyrimidine in the side chain with strobilurin pharmacophore were synthesized and their biological activities were tested. The compounds were confirmed and characterized by 1H‐NMR, elemental analysis and mass spectroscopy. The bioassays indicated that most of the compounds 1 exhibited potent antifungal activities against Colletotrichum orbiculare, Botrytis cinerea Pers and Phytophthora capsici Leonian at a concentration of 50 μg mL?1. Notably, compound 1b (R = 2,5‐dimethylphenyl) showed better antifungal activity against all the tested fungi than the commercial strobilurin fungicide azoxystrobin. 相似文献
949.
A nano‐crystalline In2O3 was synthesized using calcinations methods and was used as a photocatalyst to degrade sulfan blue (SB) dye. In addition, this study addresses the conditions of the degradation and the factors that influenced the catalysis. In2O3 was prepared by calcining In(OH)3 at heat ranges of 100–700 °C for 24 h. The In2O3 was characterized using field emission scanning electron microscopy (FE‐SEM), an X‐ray diffractometer (XRD), thermogravimetric analysis (TGA), and high‐resolution X‐ray photoelectron spectroscopy (HR‐XPS). The activities of these samples were tested for the photocatalytic degradation of SB dye. The results indicated that the In(OH)3 that was calcined at 300 °C for 24 h had the best performance. 相似文献
950.
Yisheng Sun Zhao Zhao Qiangsheng Feng Qinqin Xu Longxian Lü Ji‐Kai Liu Ling Zhang Bin Wu Yong‐Quan Li 《Helvetica chimica acta》2013,96(1):76-84
Investigation of the cultured mycelia of Cordyceps ophioglossoides resulted in the isolation and characterization of three new unusual spiro[4.5]decane sesquiterpenes, cordycepol A ( 1 ), cordycepol B ( 2 ), and cordycepol C ( 3 ), and a new fumagillol analogue, cordycol ( 4 ). Their structures were established by spectroscopic means. The cytotoxic activities were also evaluated, compounds 3 and 4 showing their IC50 values in the range of 12–33 μg/ml against HeLa and HepG2 (Table 3). In addition, 3 and 4 were not obviously harmful towards normal liver cell lines LO2, showing IC50 values above 80 μg/ml. 相似文献