固体表面化学发光分析 Ⅰ.不渗透阻挡技术的应用和研究

本文应用不渗透阻挡技术在固体基质上保持恒定的化学发光区域，实现了固体表面化学发光分析，并对固体表面化学发光特性，发光的均匀性和重视性，固体基质的选择和纯化等方面进行了研究，测定了１３种无机及生物活性物质固体表面化学发光的线性范围及检测限。由于此法克服了固体基质荧光分析和固体表面室温磷光分析的散射光背景的影响，获得了更高的信噪比和更好的检测限。     

Parallel iterative reaction path optimization in ab initio quantum mechanical/molecular mechanical modeling of enzyme reactions

The determination of reaction paths for enzyme systems remains a great challenge for current computational methods. In this paper we present an efficient method for the determination of minimum energy reaction paths with the ab initio quantum mechanical/molecular mechanical approach. Our method is based on an adaptation of the path optimization procedure by Ayala and Schlegel for small molecules in gas phase, the iterative quantum mechanical/molecular mechanical (QM/MM) optimization method developed earlier in our laboratory and the introduction of a new metric defining the distance between different structures in the configuration space. In this method we represent the reaction path by a discrete set of structures. For each structure we partition the atoms into a core set that usually includes the QM subsystem and an environment set that usually includes the MM subsystem. These two sets are optimized iteratively: the core set is optimized to approximate the reaction path while the environment set is optimized to the corresponding energy minimum. In the optimization of the core set of atoms for the reaction path, we introduce a new metric to define the distances between the points on the reaction path, which excludes the soft degrees of freedom from the environment set and includes extra weights on coordinates describing chemical changes. Because the reaction path is represented by discrete structures and the optimization for each can be performed individually with very limited coupling, our method can be executed in a natural and efficient parallelization, with each processor handling one of the structures. We demonstrate the applicability and efficiency of our method by testing it on two systems previously studied by our group, triosephosphate isomerase and 4-oxalocrotonate tautomerase. In both cases the minimum energy paths for both enzymes agree with the previously reported paths.     

Facile solvent-free synthesis of pure-phased AlN nanowhiskers at a low temperature

Pure hexagonal aluminum nitride (AlN) nanowhiskers have been successfully synthesized by directly reacting AlCl₃ with NaN₃ in non-solvent system at the low temperature of 450 °C for 24 h. The obtained products are characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and selected area electron diffraction, which show that the obtained products are hexagonal phase AlN nanowhiskers with width from 10 to 80 nm and length up to several micrometers. The influencing factors of the formation of AlN nanowhiskers were discussed and a possible growth mechanism for AlN nanowhiskers was proposed. Additionally, the study on the corresponding optical properties and catalytic properties is also carried out.     

N-取代苯甲酰基-N'-取代芳基硫脲的合成、晶体结构及生物活性

为了寻找新的高活性农药, 利用工业易得的三氟羧草醚及其中间体为起始原料, 设计合成了9个未见报道的N-取代苯甲酰基-N'-取代芳基硫脲化合物, 结构经IR, ¹H NMR, 元素分析确认. X射线衍射测定了化合物4b的晶体结构, 结果表明: 其分子属于三斜晶系, 空间群P-1, a＝0.51588(19) nm, b＝1.0766(4) nm, c＝2.0596(8) nm, α＝81.113(6)°, β＝89.702(6)°, γ＝78.131(6)°, V＝1.1056(7) nm³, D_c＝1.445 Mg/m³, Z＝2, F(000)＝492, μ＝0.319 mm^－1. 初步生物活性测试结果表明, 部分化合物具有较好的除草活性.     

Modification of the halogen end groups of polystyrene prepared by ATRP

The stabilization modification of the halogen end groups of polystyrene prepared by atom transfer radical polymerization (ATRP) has been attempted. The reaction mechanism adopted is radical chain transfer reaction, and iso-propylbenzene is employed as not only the chain transfer agent but also the solvent. Moreover, Cu⁰ is used as the acceptor of the transformed halogen atom in some experiments. As evidenced by ¹H NMR analysis of the modified products, the halogen end group can really be converted into the much more stable carbon-hydrogen structure. When Cu⁰ is not used, the conversion of the halogen end groups rises rapidly during the early stage and the increase rate slows down after about 8 h reaction. In view of the influence of reaction temperature on the modification, the conversion increases almost exponentially with temperature in the range of 80-100 °C, and the increase rate slows down at higher temperature. ¹H NMR and SEC analyses prove that the modification reaction does not destroy the polymer backbone and the molecular weights remain almost the same as those of the unmodified samples. When Cu⁰ is introduced, the modification reaction proceeds much rapidly, the conversion of the halogen end groups rises almost linearly at the early stage and the nearly complete (>95%) dehalogenation of the polymeric chains is observed after only 12 h reaction. However, the molecular weights rise and the polydispersities become wider after the modification, which implies that the modification is accompanied with the couple termination of the polystyrene radicals besides chain transfer reaction. Furthermore, the couple termination can be restrained at some lower catalyst concentration. Indeed, the modified polymers show improved thermal stability, the initial weight loss temperatures is increased from 196 °C to 378 °C for the linear polystyrene and from 203 °C to 261 °C for the hyperbranched polystyrene.     

LC Determination of Curcumin in Dog Plasma for a Pharmacokinetic Study

A rapid, simple, and sensitive high-performance liquid chromatographic method for quantification of curcumin in dog plasma has been developed and validated. After addition of the internal standard (berberine), plasma was acidified and extracted with ethyl acetate. Analysis was performed on a C₁₈ column. The mobile phase was acetonitrile–5% acetic acid, 52:48 (v/v) and the flow rate 1.0 mL min^?1. The eluent was monitored at 425 nm. Chromatographic separation was achieved in less than 7 min and the calibration plot was linear over the concentration range 2–128 ng mL^?1. Intra- and inter-assay variability were less than 7.3%. The accuracy ranged from 98.7 to 105.0%. The method was successfully applied to a pharmacokinetic study of curcumin in dogs.     

LyP-1 peptide-functionalized gold nanoprisms for SERRS imaging and tumor growth suppressing by PTT induced-hyperthermia

The gold nanoprisms (GNPs) have exhibited special plasmonic properties for biomedical applications because of their unique shapes and dimensions. Based on their optical performance, the NIR dye IR780 not only enabled the GNPs-based nanosystem as SERRS nanoparticles for Raman-encoded molecular imaging, but also enhanced the plasmonic photothermal property by laser irradiation. Meanwhile, the GNPs/IR780-Lyp-1 by introduction of tumor-homing peptide segment LyP-1, which presents high affinity to p32 protein, demonstrated the increased enrichment in tumor region and enhanced photothermal therapy efficacy.     

Differential-pulse voltammetric determination of trace formaldehyde using magnetic microspheres and magnetic electrode

A new type of magnetic polymer microsphere containing acylhydrazine groups on the surface was synthesized. They can be reacted with formaldehyde to produce an electroactive adduct. Reduction of these derivatives following aggregation on a magnetic electrode is possible and is effective in the indirect determination of formaldehyde. The experimental conditions and electrode structure are discussed. Under the optimum conditions, it was found that the peak potential (Ep) of formaldehyde is -1.01 V (vs. Ag/AgCl). Formaldehyde in the range 1-1000 micrograms l-1 can be determined. The detection limit for formaldehyde is 0.3 microgram l-1 and the relative standard deviation for the determination of 100 micrograms l-1 formaldehyde was 2.26%. The method was applied to the determination of formaldehyde in environmental samples with satisfactory results.     

Determination of trace hydrazine by differential pulse voltammetry using magnetic microspheres

A new type of magnetic polymer microspheres containing ketone groups on the surface was synthesized. It can be reacted with hydrazine to produce electroactive adduct. Reduction of this derivative that was aggregated on the magnetic electrode is possible and effective in indirect determination of hydrazine. The experimental conditions and electrode structure were discussed. Under optimum conditions, It was found that the peak potential (Ep) of hydrazine is -1.06 V (vs. Ag/AgCl). Hydrazine in the range 0.3-500 mug l(-1) can be determined. The detection limits for hydrazine is 0.1 mug l(-1). The relative standard deviation for determination of 100 mug l(-1) hydrazine was 2.43 %. The method was applied to the determination of hydrazine in water samples with satisfactory results.     

The tautomerism of Omeprazole in solution: a 1H and 13C NMR study

The tautomerism of 5(6)-methoxy-2-([(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl] sulfinyl)-1H-benzimidazole (omeprazole) was determined in solution, K(T) = 0.59 in THF at 195 K, in favor of the 6-methoxy tautomer. The assignment of the signals was made by comparison with its two N-methyl derivatives in acetone-d6 and through theoretical calculations of the absolute shieldings (GIAO/DFT/6-311++G**).