聚乳酸载药微球制备及释药性能研究最新进展

对可生物降解材料聚乳酸作为药物载体制备微球制剂的研究状况进行了综述。针对目前限制聚乳酸微球制剂临床应用存在的问题,重点介绍了降低药物突释,提高药物包封率,改善多肽和蛋白药物微球释药性能等方面研究的最新进展。聚乳酸载药微球在药物传输中有着广阔的研究和应用前景。     

光折变材料的带隙结构研究

利用光子晶体的概念和时域有限差分方法计算了当光折变材料的空间折射率呈一维正弦变化时其内部的带隙结构情况,表明在光折变材料中存在极窄的光子带隙。最后讨论了折射率(n)、折射率调制幅度(△n)、周期长度(D)及周期数(N)对光子带隙的影响。     

A New Method for Testing Leverage Effect

Leverage effect often arises in many fields,such as financial risk management, portfolio and option pricing. However,it still remains to be studied that whether there is leverage effect or not in real data. Based on local polynomial regression estimation and Kolmogorov-Smirnov nonparametric test, this paper introduces a new nonparametric test statistic for the leverage effect, and some asymptotic properties are also presented. Simulation studies show that the proposed method performs well. Finally, empirical studies on SP500 index and Microsoft data imply that leverage effect exists in the real data, which is consistent with the idea in finance.     

A liquid chromatography–tandem mass spectrometry method for preclinical pharmacokinetics and tissue distribution of hydrolyzable tannins chebulinic acid and chebulagic acid in rats

A simple and sensitive liquid chromatography–tandem mass spectrometry method was developed for the simultaneous determination of chebulinic acid and chebulagic acid in rat plasma and tissues and well used in the pharmacokinetic and tissue distribution studies after intraperitoneal injection administration. Samples were processed with methanol by protein precipitation, and chromatographic separation was performed on an Agilent Zorbax SB‐C₁₈ column (50 × 2.1 mm, 1.8 μm) with a mobile phase consisting of methanol and water containing 0.1% formic acid (60:40, v/v). Quantification was performed by selected reaction monitoring with m/z 977.1 → 806.8 for chebulagic acid, m/z 979.0 → 808.7 for chebulinic acid and m/z 851.2 → 704.9 for the internal standard. Good linearity was observed over their respective concentration range. The pharmacokinetic study showed that both compounds reached their peak concentration values (605.8 ± 35.6 ng/mL for chebulinic acid and 1327.1 ± 118.6 ng/mL for chebulagic acid) at the same time of 0.9 h following intraperitoneal injection administration. The two compounds could be detected in blood‐abundant tissues. The kidney had the highest concentrations (462.6 ± 138.5 ng/g for chebulinic acid and 1651.7 ± 167.7 ng/g for chebulagic acid) at 1 h post‐dose, followed by the heart, liver, spleen and lung.     

Room-Temperature Guerbet Reaction with Unprecedented Catalytic Efficiency and Enantioselectivity

We report herein an unprecedented highly efficient Guerbet-type reaction at room temperature (catalytic TON up to >6000). This β-alkylation of secondary methyl carbinols with primary alcohols has significant advantage of delivering higher-order secondary alcohols in an economical, redox-neutral fashion. In addition, the first enantioselective Guerbet reaction has also been achieved using a commercially available chiral ruthenium complex to deliver secondary alcohols with moderate yield and up to 92 % ee. In both reactions, the use of a traceless ketone promoter proved to be beneficial for the catalytic efficiency.     

On Accelerating Monte Carlo Integration Using Orthogonal Projections

Methodology and Computing in Applied Probability - Monte Carlo simulation is an indispensable tool in calculating high-dimensional integrals. Although Monte Carlo integration is notoriously known...     

基于光谱特征的雅鲁藏布大峡谷森林枯落物水源涵养能力反演研究

水源涵养是生态系统重要的服务功能，森林作为一种复杂的生态系统，其组成部分对于水源涵养的贡献率各不相同；森林枯落物直接覆盖于地表，既来自于林冠层也抑制土壤层的水分蒸散，因此枯落物层在水源涵养功能中发挥了重要作用。遥感和高光谱技术为远距离识别面状区域的水源涵养能力提供了解决方案，特别在高原地区，遥感是获取地表信息的快速手段。以雅鲁藏布大峡谷为研究区，用ASD(便携式地物)光谱仪测定主要树种(高山松、林芝云杉和川滇高山栎)的叶片高光谱数据并构建植被指数，同时，通过样地采样获取枯落物样本并计算样本的持水拦蓄性能，然后建立植被指数与有效拦蓄量的多元回归模型。在此基础上，基于Sentinel-2影像反演大峡谷主要树种枯落物的水源涵养能力分布情况，最后结合验证点对反演模型进行精度评价。结果显示：（1）三类树种的叶片反射率趋势相似，川滇高山栎的反射率最高，高山松次之，林芝云杉最低；（2）枯落物的有效拦蓄量从大到小排序为：林芝云杉(48.36 t·ha-1)>川滇高山栎(39.24 t·ha-1)>高山松(32.32 t·ha-1)。林芝云杉枯落物的分解程度和蓄积量均最高，因此持水拦蓄能力最强；川滇高山栎的革质叶片不利于分解堆积，进而限制蓄水能力；高山松含有较多油脂，不易被水浸湿，导致持水能力较弱。（3）通过Person相关系数分析和多元线性回归模型得知，叶片蜡质参数和衰减程度越高，枯落物的水源涵养能力越弱；植被生长态势越好、色素和叶片水分含量越高，其水源涵养能力越强。（4）枯落物水源涵养能力反演模型的精度评价结果良好，高山松、林芝云杉和川滇高山栎的样本检验点拟合优度R2分别为0.943，0.815和0.812，均方根误差RMSE分别为1.597，2.270和1.953，表明模型可以用于大峡谷森林枯落物水源涵养能力的预测分布研究。     

Three new Anthraquinones,one new Benzochromene and one new Furfural glycoside from Lasianthus acuminatissimus

Three new anthraquinones, lasianthurin B (1), C (2), lasianthuoside D (3), a new benzochromene, lasianthurin D (4), and a new furfural glycoside, lasianthuoside E (5), together with one known compound 4- hydroxymethyl-2-furaldehyde (6) were isolated from an alcohol extract of the root of Lasianthus acuminatissimus. Their structures were elucidated on the basis of extensive spectroscopic data analysis (including 1D, 2D NMR, X-ray, and MS experiments) and comparsion to literature data.     

Green synthesis and application of nanoscale zero-valent iron/rectorite composite material for P-chlorophenol degradation via heterogeneous Fenton reaction

A zero-valent iron/rectorite nanocomposite (NZVI/rectorite) was developed as a heterogeneous H₂O₂ catalyst for P-chlorophenol degradation. The physicochemical properties of NZVI/rectorite were characterized by various techniques including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive spectrometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Brunauer–Emmett–Teller analysis. Results showed that NZVI sphere nanoparticles were successfully loaded on the rectorite surface with less aggregation and good dispersion. Moreover, compared with acid-leached rectorite (30.91 m²/g), the NZVI/rectorite appeared to have larger surface area (50.75 m²/g). In addition, the effects of pH, reaction time, initial P-chlorophenol concentration, catalyst amount, and H₂O₂ dosage on the P-chlorophenol degradation were systematically investigated. Results showed that NZVI/rectorite presents better properties for the degradation and mineralization of P-chlorophenol compared with pristine NZVI due to the large surface area, low aggregation, and good dispersion of the former. The degradation mechanisms of P-chlorophenol by NZVI/rectorite were adsorption and reduction coupled with a Fenton-like reaction. Four successive runs of the stability and regeneration study also showed that the NZVI/rectorite were unchanged even after 100% of P-chlorophenol degradation ratio. This study has extended the application of NZVI/rectorite as environment function material for the removal of P-chlorophenol from the environment.