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991.
Yanzhu Lei Guohua Zhao Prof. Xili Tong Meichuan Liu Dr. Dongming Li Prof. Rong Geng 《Chemphyschem》2010,11(1):276-284
To obtain noble metal catalysts with high efficiency, long‐term stability, and poison resistance, Pt and Pd are assembled in highly ordered and vertically aligned TiO2 nanotubes (NTs) by means of the pulsed‐current deposition (PCD) method with assistance of ultrasonication (UC). Here, Pd serves as a dispersant which prevents agglomeration of Pt. Thus Pt–Pd binary catalysts are embed into TiO2 NTs array under UC in sunken patterns of composite spherocrystals (Sps). Owing to this synthesis method and restriction by the NTs, the these catalysts show improved dispersion, more catalytically active sites, and higher surface area. This nanotubular metallic support material with good physical and chemical stability prevents catalyst loss and poisoning. Compared with monometallic Pt and Pd, the sunken‐structured Pt–Pd spherocrystal catalyst exhibits better catalytic activity and poison resistance in electrocatalytic methanol oxidation because of its excellent dispersion. The catalytic current density is enhanced by about 15 and 310 times relative to monometallic Pt and Pd, respectively. The poison resistance of the Pt–Pd catalyst was 1.5 times higher than that of Pt and Pd, and they show high electrochemical stability with a stable current enduring for more than 2100 s. Thus, the TiO2 NTs on a Ti substrate serve as an excellent support material for the loading and dispersion of noble metal catalysts. 相似文献
992.
Oluwatosin O. Dada Lauren M. Ramsay Jane A. Dickerson Nathan Cermak Rong Jiang Cuiru Zhu Norman J. Dovichi 《Analytical and bioanalytical chemistry》2010,397(8):3305-3310
We report a multiplexed capillary electrophoresis system employing an array of 32 capillaries with a micromachined sheath-flow
cuvette as the detection chamber. The sample streams were simultaneously excited with a 473-nm laser beam, and the fluorescence
emission was imaged on a CCD camera with a pair of doublet achromat lens. The instrument produced mass detection limits of
380 ± 120 yoctomoles for fluorescein in zone electrophoresis. Capillary isoelectric focusing of fluorescent standards produced
peaks with an average width of 0.0029 ± 0.0008 pH. Capillary coating stability limits the reproducibility of the analysis. 相似文献
993.
A novel polymeric photoinitiator P(MPBP‐co‐DMAEMA), bearing side‐chain benzophenone (BP) and coinitiator amine, was synthesized through free radical copolymerization of a polymerizable photoinitiator, 4‐[(4‐maleimido)phenoxy]benzophenone (MPBP), and a polymerizable coinitiator amine, N, N‐dimethylaminoethyl methacrylate (DMAEMA). In order to find out the influences of coinitiator amine on photopolymerization, a polymeric coinitiator amine, P(DMAEMA), was also synthesized for comparison. FT‐IR, 1H NMR, and GPC analyses confirm the structures of polymers. The UV‐Vis spectra of polymeric photoinitiator P(MPBP‐co‐DMAEMA) and polymerizable photoinitiator MPBP are similar, and both exhibit high red‐shifted maximal absorption as compared with BP. The photopolymerization of 1,6‐hexanediol diacrylate (HDDA) and trimethylolpropane triacrylate (TMPTA), initiated by MPBP/DMAEMA, MPBP/P(DMAEMA), and P(MPBP‐co‐DMAEMA) systems, was studied by photo‐DSC. The results indicate that P(MPBP‐co‐DMAEMA) is most efficient for the polymerization of both HDDA and TMPTA, and MPBP/P(DMAEMA) is the least efficient of the three photoinitiating systems. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
994.
Five new coordination polymers, [Cd(1,2′-cy)0.5(bix)H2O]n (1), [Cd2(1,2′-cy)2(1,10′-phen)2(H2O)2] (2), {[Co(1,2-cy)(2,2′-bipy)(H2O)2]·2H2O}n (3) {[Cd(succ)(1,10′-phen)H2O]·H2O}n (4), and {[Cd(succ)(2,2′-bipy)H2O]·2H2O}n (5) (1,2-cy = 4-cyclohexene-1,2-dicarboxylate, succ = succinic acid, bix = 1,4-bis(imidazol-1-ylmethyl)benzene, 1,10′-phen = 1,10-phenanthroline, 2,2′-bipy = 2,2′-bipyridine), have been synthesized and characterized by single-crystallographic X-ray diffraction. Complex 1 shows a two-dimensional covalent layer structure. Complex 2 exhibits a two-dimensional supramolecular layer network composed from discrete fundamental units. Complex 3 exhibits a one-dimensional covalent chain-like structure, which further extends to a two-dimensional supramolecular structure with hydrogen bonding and π-π interactions respectively. Complexes 4 and 5 show three-dimensional supramolecular networks composed from one-dimensional chain-like covalent structures. Furthermore, the magnetic property of complex 3 and fluorescent properties of complexes 1, 2, 4 and 5 have also been studied. 相似文献
995.
A pcu network can be ordered through trigonal bipyramidal nanocages as secondary building blocks, which have the striking feature of hydrophilic affinity to the polar molecules and π-π interactions for aromatic molecules. 相似文献
996.
FDU-15-SO3H, a solid acid material prepared from the sulfonation of FDU-15 mesoporous polymer, has been demonstrated to serve as an efficient catalyst in the esterification of palmitic acid with methanol as well as in the transesterification of fatty acid-edible oil mixture. FDU-15-SO3H achieved an acid conversion of 99.0% when the esterification was carried out at 343 K with a methanol/palmitic acid molar ratio of 6:1 and 5 wt% catalyst loading. It was capable of giving 99.0% yield of fatty acid methyl esters (FAME) when the transesterification of soybean oil was performed at 413 K and the methanol/oil weight ratio of 1:1. FDU-15-SO3H was further applied to the transesterification/esterification of the oil mixtures with a varying ratio of soybean oil to palmitic acid, which simulated the feedstock with a high content of free fatty acids. The yield of FAME reached 95% for the oil mixtures containing 30 wt% palmitic acid. This indicated the sulfonated mesopolymer was a potential catalyst for clean synthesis of fuel alternative of biodiesel from the waste oil without further purification. 相似文献
997.
建立液相色谱-串联质谱(LC-MS/MS)检测生物合成咖啡酸苯乙酯体系中咖啡酸(Caffeic acid,CA)和咖啡酸苯乙酯(Caffeic acid phenethylester,CAPE)的方法。采用LC-MS/MS电喷雾电离(ESI),负离子选择反应监测(SRM)模式检测。以V(乙腈)∶V(水)∶V(冰醋酸)=55∶45∶0.5为流动相,流速1.0mL/min,Hypersil C18色谱柱分离并检测生物合成咖啡酸苯乙酯体系中的咖啡酸以及咖啡酸苯乙酯的含量,并对生物合成咖啡酸苯乙酯的收率进行了动力学分析。本方法在进样量为0.2~20μg时具有良好的线性关系,咖啡酸和咖啡酸苯乙酯样品的加标回收率分别为93.4%~98.2%和90.3%~97.8%,相对标准偏差分别为1.79%~2.56%和1.82%~3.67%,咖啡酸苯乙酯收率在3d内可以达到15.54%,表明本方法简便、快速、可靠。 相似文献
998.
Shu‐Wei Tang Jing‐Dong Feng Yong‐Qing Qiu Hao Sun Feng‐Di Wang Ying‐Fei Chang Rong‐Shun Wang 《Journal of computational chemistry》2010,31(14):2650-2657
Electronic structures and nonlinear optical properties of two highly deformed halofullerenes C3v C60F18 and D3d C60Cl30 have been systematically studied by means of density functional theory. The large energy gaps (3.62 and 2.61 eV) between the highest occupied and lowest unoccupied molecular orbitals (HOMOs and LUMOs) and the strong aromatic character (with nucleus‐independent chemical shifts varying from ?15.08 to ?23.71 ppm) of C60F18 and C60Cl30 indicate their high stabilities. Further investigations of electronic property show that C60F18 and C60Cl30 could be excellent electron acceptors for potential photonic/photovoltaic applications in consequence of their large vertical electron affinities. The density of states and frontier molecular orbitals are also calculated, which present that HOMOs and LUMOs are mainly distributed in the tortoise shell subunit of C60F18 and the aromatic [18] trannulene ring of C60Cl30, and the influence from halogen atoms is secondary. In addition, the static linear polarizability and second‐order hyperpolarizability of C60F18 and C60Cl30 are calculated using finite‐field approach. The values of and for C60F18 and C60Cl30 molecules are significantly larger than those of C60 because of their lower symmetric structures and high delocalization of π electrons. © 2010 Wiley Periodicals, Inc. J Comput Chem 2010 相似文献
999.
Junhua Luo Chenghu Li Zhenlai Liu Xinxing Wang Rong Liu Li Jiang 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):421-426
Cross-sections for (n,p), (n,α), (n,n′α), (n,t) and (n,2p) reactions have been measured on 139La isotope at the neutron energy 14.8 MeV using the activation technique in combination with high-resolution gamma-ray spectroscopy.
Neutrons were produced via the 3H(d,n)4He reaction using a solid tritium–titanium target. The neutron fluences were determined using the monitor reaction 27Al(n,α)24Na. The neutron energy in this measurement was determined by cross section ratios for the 90Zr(n,2n)89m+gZr and 93Nb(n,2n)92mNb reactions. Data are reported for the following reactions: 139La(n,p)139Ba, 139La(n,α)136Cs, 139La(n,n′α)135mCs, 139La (n,t)137mBa, and 139La(n,2p)138Cs. The cross sections were discussed and compared with experimental data found in the literature, and with the comprehensive
evaluation data in ENDF/B-VII.0, JENDL-3.3, JEFF-3.1/A, and TENDL-2008 libraries. 相似文献
1000.
同位素稀释高效液相色谱串联质谱法测定猪肝中地塞米松和倍他米松残留量 总被引:1,自引:0,他引:1
建立了同位素稀释高效液相色谱串联质谱法测定猪肝中地塞米松和倍他米松残留量的分析方法。样品经酶解后用乙腈提取,再经C18固相萃取和碳酸钠溶液液液萃取净化,净化后的样品经氮气吹干后用流动相溶解。采用Hypercarb C18柱,以乙腈-水-甲酸(95∶5∶0.5,V/V)混合溶液为流动相,进行高效液相色谱串联质谱分析,同位素内标法定量分析。地塞米松和倍他米松的检出限为别为0.12和0.14μg/kg,定量限分别为0.42和0.47μg/kg。在添加浓度0.75~2.0μg/kg范围内,平均添加回收率为97.3%~111%,批内和批间相对标准偏差(RSD)分别为1.85%~5.65%和2.78%~7.98%。待测物定量离子对峰面积与内标物峰面积比值与标样浓度在10~500μg/L范围内呈良好的线性关系,线性回归系数大于0.9997。 相似文献