Influence of acid treatments of carbon nanotube precursors on Ni/CNT in the synthesis of carbon nanotubes

The Ni/CNT catalyst was fabricated by directly dipping carbon nanotube precursors refluxed in 4 M of nitric acid into Ni electroless plating bath, and used to synthesize new carbon nanotubes. The experimental results indicate that the duration of acid-treatment of carbon nanotubes precursors exerts a great influence on the catalysis of Ni/CNT in the synthesis of carbon nanotubes and hence the structures of the new carbon nanotubes. When the carbon nanotubes precursors were refluxed for 0.5 h in 4 M of nitric acid, bamboo-shaped carbon nanotubes (BSCNT) or Y junction carbon nanotubes in the carbon products were obtained. As the duration of acid-treatment of carbon nanotubes precursors increased to 6 h, the as-prepared Ni/CNT displayed higher activity, and the carbon nanotube products were high pure without any Y junction structure or any separation layers in hollow.     

钕诱导番茄产生抗性的时间研究

采用盆栽试验研究了Nd3 在不同诱导时间对番茄叶抗性指标(过氧化物酶(POD)、多酚氧化酶(PPO)和苯丙氨酸解氨酶(PAL)活性、细胞膜透性、氧自由基(O2-·)产生速率和木质素含量)的影响.结果表明:从第3 d开始,Nd3 诱导提高番茄叶内PAL活性,第3d增幅也最大,达32.30%,维持时间为诱导后第3～5 d;Nd3 诱导后第1～2 d POD活性升高,第1 d增幅最大,维持时间是诱导后第1～2 d;Nd3 诱导后1～3 d,PPO活性升高,第1 d增幅最大,维持时间是诱导后第1～3 d;从诱导后第2 d开始,Nd3 降低细胞膜透性,第3 d时降幅最大,为54.33%,持续时间为诱导后第2～5 d;从第3 d开始,Nd3 诱导降低氧自由基产生速率,第4 d降幅最大,第3 d氧自由基产生速率最低,持续时间为诱导后第3～5 d;从第4 d开始,Nd3 诱导提高木质素含量,5 d时有继续升高的趋势.从不同诱导时间番茄叶PAL活性、细胞膜透性、氧自由基产生速率的变化来看,在Nd3 诱导的第3 d,番茄产生的抗性最强.     

Thiazolium-mediated multicomponent reactions: a facile synthesis of 3-aminofuran derivatives

[reaction: see text] A facile synthesis of highly functionalized 3-aminofuran derivatives by the multicomponent reactions of thiazolium salts, aldehydes, and DMAD is described.     

健康老年人血清锌,铜,镁含量的调查

应用原子吸收分光光度法对济南市健康老年人血清中铜、锌、镁含量进行了测定。结果表明，健康老年人血液铜、锌水平低，但铜、锌比值正常，而镁的含量则较高。提示这组健康老年人未患心、脑血管疾病及糖尿病的原因可能与铜、锌、镁等微量元素有关。     

纳米级TiO2粉体的制备研究——Ⅱ.絮凝剂及其浓度的影响

采用溶胶-凝胶-超临界流体干燥(SCFD)法制备纳米级TiO₂超细粉，详细考察了不同絮凝剂及其浓度对TiO₂织构和结构性质的影响。结果表明，利用强碱溶液作为絮凝剂，浓度为5 mol·L^-1是制备大孔高比表面TiO₂超细粉较为适宜的条件。     

Synthesis and Characteristics of a New Fluorogenic Substrate for Horseradish Peroxidase

N,N′-Dicyanomethyl-o-phenylenediamine was synthesized with a 90% yield by a reaction ofo-phenylenediamine with chloroacetonitrile in triethylamine. Our experimental results showed that it was the effective fluorogenic substrate for horseradish peroxidase (HRP) and hemin. TheK_mfor the HRP system was 48 μM,and that for hemin was 1.3 μM.Properties of the substrate were evaluated from the detection limits of enzymes and H₂O₂. The linear ranges for the determination of HRP and hemin were 21–150 pMand 2–20 nM,respectively. The linear range for the determination of H₂O₂using HRP or hemin was 18–140 and 60–1000 nM,respectively. The structural elucidation of the fluorescent product using NMR and mass spectral techniques was proposed to be 1,2-dihydro-2-imido-imidazo[1,2-a] quinoxaline. Based on the product structure and earlier reports, the possible reaction mechanism of HRP and the substrate was also proposed, i.e., two steps for ring closures, one step of isomerization, and a final step of oxidative dehydrogenation.     

Investigations of the EPR parameters for Sm3+ ions in KY3F10 and LiYF4 crystals

In this paper, we calculate the EPR parameters (g factors g parallel, g perpendicular and hyperfine structure constants A parallel, A perpendicular) of rare earth ion Sm3+ in fluoride crystals KY3F10 and LiYF4 from the perturbation formulas of EPR parameters for a 4f5 ion in tetragonal symmetry. In these formulas, the crystal-field J-mixing of the first and second excited-state multiplets 6H(7/2) and 6H(9/2) into the ground state multiplet 6H(5/2), the mixtures among the states with the same J value via spin-orbit coupling interaction and the interactions between the ground Kramers doublet Gammagamma and the same irreducible representation as Gammagamma in other 11 Kramers doublets Gammax within 6HJ (J=5/2, 7/2, 9/2) states via crystal-field and orbital angular momentum (or hyperfine structure) are considered. The calculated results (which are in agreement with the observed values) are discussed.     

A fully automated nanoelectrospray tandem mass spectrometric method for analysis of Caco-2 samples

Caco-2 cells offer a means to rapidly screen permeability of drug candidates, allowing pharmaceutical companies to eliminate candidates unable to cross the intestinal barrier early in the discovery process. This screening process is typically performed by conventional liquid chromatography/tandem mass spectrometry (LC/MS/MS), which can require time-consuming method development. An alternative to LC/MS/MS, automated nanoelectrospray tandem mass spectrometry (nanoESI-MS/MS), is introduced. This novel approach requires an off-line ZipTip desalting step followed by automated nanoESI-MS/MS, using the NanoMate 100 and ESI Chip. In addition to reduced method development time, automated nanoESI-MS/MS also offers no carry-over between samples, low sample consumption, and ease-of-use as compared with conventional pulled-capillary nanoelectrospray. Furthermore, the infusion system described has the potential to be high-throughput. A comparison of Caco-2 samples analyzed both by LC/MS/MS and by automated nanoESI-MS/MS is presented. The permeability and recovery data of the two compounds analyzed in this study obtained from conventional LC/MS/MS and by automated nanoESI-MS/MS were in excellent agreement.     

一种新的滤纸基质固体表面低温荧光(燐光)测定装置

对自行研制的铜制滤纸基质低温荧光（燐光）测定的样品支架，进行了滤纸基质固体表面低温荧光测定的可行性研究。与同类冷冻装置和室温装置比较，本装置用于滤纸基质固体表面低温荧光（燐光）测定具有以下优点；样品的分析周期大大地缩短，由45min缩短为5-6min；装置简单、便宜耐用；操作简便，简化了室温测定时的滤纸干燥程序，应用范围广，方法的重现性好，检样分析结果的相对标准偏差RSD%小于10%，荧光（燐光）分析灵敏度高，检出限低，线性范围宽。     

3－苯氧甲基－6－（2，4－二氟苯基）－7H-1,2,4-三唑并[3,4-b][1,3,4]噻二嗪的合成与晶体结构研究

由苯氧乙酸出发，经多步反应，制得3-苯氧甲基－4－氨基－5－巯基－1，2， 4－三唑，它与2-氯－2'，4'－二氟苯乙酮进行环化反应，生成3-苯氧甲基－6－（ 2,4-二氟苯基）－7H-1,2,4-三唑并[3,4-b][1,3,4]噻二嗪，通过元素分析、红外 光谱、核磁共振氢谱与碳谱、质谱进行表征，并利用单晶X射线衍射法测定其结构 。晶体属单斜晶系、P2_(1/c)空间群，a = 1.339(3) nm, b = 1.4683(4) nm, c = 0.8606(2) nm, β = 108.49(2)°, Z = 4, F(000) = 736, R_1 = 0.0509。还 对均三唑并噻二唑两类稠杂环的晶体结构作了比较。