Guided-wave second harmonics in Nd:YCOB optical waveguides for integrated green lasers

We report on guided-wave second-harmonic generations in nonlinear Nd:YCa₄O(BO₃)₃ (Nd:YCOB) optical waveguides that are produced by the low-fluence swift Ar⁸⁺ ion irradiation. The guided-wave second harmonics are realized through the frequency doubling and the self-frequency-doubling of the waveguides under the optical pumps at wavelengths of 1064 and 810 nm, respectively. By virtue of the self-frequency-conversion configuration, the Nd:YCOB waveguides are promising candidates as novel, compact, miniature green laser sources.     

Elemental compositions of PM2.5 and TSP in Lijiang,southeastern edge of Tibetan Plateau during pre-monsoon period

PM_2.5 and total suspended particulate (TSP) samples were collected at Lijiang, southeastern Tibetan Plateau, China. Sixteen elements (Al, Si, S, K, Ca, Cr, Mn, Ti, Fe, Ni, Zn, As, Br, Sb, Pb and Cu) were analyzed to investigate their elemental compositions during the pre-monsoon period. The results showed that Ca was the most abundant element in both PM_2.5 and TSP samples. The enrichment factors (EFs) of Si, Ti, Ca, Fe, K and Mn were all below 10 for both PM_2.5 and TSP, and these elements also had lower PM_2.5/TSP ratios (0.32–0.34), suggesting that they were mainly derived from crustal sources. Elements Cu, Zn, S, Br and Sb showed strong enrichment in PM_2.5 and TSP samples, with their PM_2.5/TSP ratios ranging from 0.66 to 0.97, indicating that they were enriched in the fine fractions and influenced by anthropogenic sources. Analysis of the wind field at 500 hPa and calculations of back trajectories indicated that Al, Si, Ca, Ti, Cr, Mn and Fe can be influenced by transport from northwestern China during the dust-storm season, and that S, K, Ni, Br and Pb reached high concentrations during westerly transport from south Asia. Combined with the principle component analysis and correlation analysis, elements of PM_2.5 samples were mainly from crustal sources, biomass burning emissions and regional traffic-related sources.     

Simple and sensitive monitoring of sulfonamide veterinary residues in milk by stir bar sorptive extraction based on monolithic material and high performance liquid chromatography analysis

A simple, rapid, and sensitive method for the quantitative monitoring of five sulfonamide antibacterial residues (SAs) in milk was developed by stir bar sorptive extraction (SBSE) coupling to high performance liquid chromatography with diode array detection. The analytes were concentrated by SBSE based on poly (vinylimidazole–divinylbenzene) monolithic material as coating. The extraction procedure was very simple, milk was diluted with water then directly sorptive extraction without elimination of fats and protein in samples was required. To achieve optimum extraction performance for SAs, several parameters, including extraction and desorption time, desorption solvent, ionic strength and pH value of sample matrix were investigated. Under the optimized experimental conditions, low detection limits (S/N = 3) quantification limits (S/N = 10) of the proposed method for the target compounds were achieved within the range of 1.30–7.90 ng/mL and 4.29–26.3 ng/mL from spiked milk, respectively. Good linearities were obtained for SAs with the correlation coefficients (R²) above 0.996. Finally, the proposed method was successfully applied to the determination of SAs compounds in different milk samples and satisfied recoveries of spiked target compounds in real samples were obtained.     

Sensitive and Selective LC–ESI–MS Analysis of Aesculin in Rat Plasma

A rapid and sensitive liquid chromatography–electrospray ionization mass spectrometry method was developed for the determination of aesculin in rat plasma. The analyses were chromatographed on a Zorbax Extend-C18 analytical column (150 × 2.1 mm I.D., 5 µm) with 30:70 (v/v) methanol–0.1% formic acid as mobile phase. Detection was performed by triple-quadrupole tandem mass spectrometry in multi-reaction-monitoring mode with an electrospray ionization source. The method was validated for accuracy and precision, and linearity in the two matrices was good. The assay was linear in the range 12.5–1,800 ng mL^?1. The lower limit of quantification of aesculin (LLOQ) was 12.5 ng mL^?1. The recovery of aesculin and tinidazole (IS) were well above 85%. The within- and between-batch accuracy was 100–104% and 97–109%, respectively. There were no stability-related problems in the procedure for the analysis of aesculin. The method was successfully used in a preclinical study of the pharmacokinetics of aesculin in rats.     

A Cobalt Supramolecular Compound Constructed from 4, 6-Di(1-imidazolyl)-1, 3, 5-triazine-2-one: Synthesis,Characterization and Magnetic Property

A cobalt(II) coordination polymer, [Co(dimto)₂(H₂O)₂]·4H₂O[1, dimto=4,6-di(1-imidazolyl)-1,3,5-triazine-2-one], has been prepared under solvothermal condition. Single-crystal structural analysis reveals that compound 1 crystallizes in the orthorhombic space group Ibca(No.73) with a=1.80696(12) nm, b=1.93224(11) nm, c=1.36798(10) nm, V=4.7763(5) nm³ and R₁=0.0438. Compound 1 is a 3D supramolecular architecture composed of 1D wave-like chains with hydrogen bonds and π-π interactions. Compound 1 was further characterized by powder X-ray diffraction(PXRD), infrared(IR) spectroscopy, thermogravimertic analysis(TG) and elemental analysis. Additionally, the magnetic property of compound 1 was also investigated.     

蛋黄-壳结构Fe3O4@SiO2@PMO磁性微球的制备及对漆酶的固定化

以蛋黄-壳结构的Fe₃O₄@SiO₂@PMO磁性微球作为载体, 采用交联法对漆酶进行固定, 考察了戊二醛浓度等对固定效果的影响, 并对固定后漆酶的活性进行了研究. 结果表明, 蛋黄-壳结构的磁性微球负载漆酶仅需6 h, 磁性微球对漆酶的固载量高达475 mg/g. 固定后漆酶的稳定性显著提高, 在pH=2.5~4.5的强酸性条件下, 固定后漆酶酶活仍可保持70%以上, 即使温度升高至60 ℃, 固定后漆酶的相对酶活仍保持65%以上. 这说明漆酶经所合成的材料固定后, 其耐酸和耐热能力都明显优于游离漆酶. 包覆的Fe₃O₄粒子使得材料很容易经磁铁分离法回收, 固定后漆酶经磁分离循环使用10次后仍然能保留85%的酶活, 具有良好的可操作性和稳定性, 有效降低了漆酶的使用成本.     

铌酸锂钠钾纳米粉体的溶胶-凝胶法合成及其相转变

采用化学络合法将Nb2O5转化为可溶性铌盐作为铌源, 用溶胶-凝胶法, 在500～650 ℃成功煅烧合成了平均晶粒尺寸为20～60 nm的纯钙钛矿相铌酸锂钠钾[(Li0.06Na0.47K0.47)NbO3]无铅压电陶瓷粉体. 研究了晶粒尺寸对铌酸锂钠钾纳米粉体相结构的影响. 结果表明, 基于纳米尺寸效应, 随着晶粒尺寸由60减小到20 nm, 铌酸锂钠钾粉体的相结构由正交相逐渐过渡到四方相, 而室温下四方相向立方相的转变将发生在20 nm以下.     

Ti-MWW/H2O2体系催化官能化烯烃环氧化

研究了Ti-MWW/H2O2催化体系对多种官能化烯烃液相环氧化的催化性能.结果表明,与钛硅分子筛TS-1相比,Ti-MWW具有更高的催化活性和环氧化产物选择性.溶剂对Ti-MWW催化环氧化反应的活性影响较大,其中水是催化丙烯酸乙酯和乙酸烯丙酯的最佳溶剂,随着C=C双键相邻官能团吸电子能力的增强,环氧化反应的催化活性下降.     

单线态氧的检测及分析应用研究进展

综述了单线态氧（^1O2）的测定方法。介绍了单线态氧的ESR、磷光光度、分光光度、化学发光和荧光法的基本原理、方法研究进展和分析应用情况,并重点介绍了化学发光法和荧光法,同时比较了这几种方法的特点。     

酶催化-荧光猝灭法测定药物中的姜黄素

酪氨酸在辣根过氧化物酶催化下被H2O2氧化为强荧光物质S,姜黄素对其荧光产生猝灭作用,据此建立了测定姜黄素的新方法。姜黄素浓度c在0．10～16．0μg/mL范围内与F0／F（F和F0分别为姜黄素存在和不存在时产物S的荧光强度）呈线性关系,线性回归方程c=5．4552F0／F-5．4860,线性相关系数r=0．9996,检出限为0．02μg/mL,测定结果的相对标准偏差为0．79％（n=10）,加标回收率为94．7％～102％。研究了pH值、各物质的量、反应时间、干扰离子等对测定的影响。该法可用于药物中姜黄素含量的测定。