Novel chiral thiazoline‐containing N―O ligands in the asymmetric addition of diethylzinc to aldehydes: substituent effect on the enantioselectivity

Several novel chiral thiazoline primary and tertiary alcohols were easily synthesized from commercially available l ‐cysteine in three steps and with high yield. These ligands were subsequently applied to the asymmetric addition of diethylzinc (Et₂Zn) to various aldehydes. Products with S configuration were obtained when thiazoline‐containing tertiary alcohol ligands were used as catalysts. The primary alcohol induced corresponding products with R configuration in 68% enantiomeric excess, which was a higher value relative to other N―O ligands possessing a primary alcohol unit in the literature. Furthermore, a plausible transition state model was proposed to explain the observed enantioselectivities. Copyright © 2012 John Wiley & Sons, Ltd.     

楔形体破坏模式下红层边坡岩体质量SMR法评价

简要介绍了边坡岩体质量分类的SMR法,将之应用于2个典型楔形体破坏模式下红层岩体高边坡稳定性宏观评价。 指出在评价过程中要注意对边坡起控制作用的优势结构面,并将其作为SMR法中结构面项评分的主要依据,这样得出的评分 值与边坡的实际情况才会比较相符。对地应力的影响进行了定性的分析,指出高地应力地区边坡SMR法应该慎用。     

Recent development of efficient electrocatalysts derived from porous organic polymers for oxygen reduction reaction

Porous organic polymers (POPs) have recently emerged as promising candidates for catalyzing oxygen reduction reaction (ORR). Compared to conventional Pt-based ORR catalysts, these newly developed porous materials, including both non-precious metal based catalysts and metal-free catalysts, are more sustainable and cost-effective. Their porous structures and large surface areas facilitate mass and electron transport and boost the ORR kinetics. This mini-review will give a brief summary of recent development of POPs as electrocatalysts for the ORR. Some design principles, different POP structures, key factors for their ORR catalytic performance, and outlook of POP materials will be discussed.     

Identification and quantification of nucleosides and nucleobases in Geosaurus and Leech by hydrophilic-interaction chromatography

A simple hydrophilic-interaction chromatography (HILIC) method was developed for the identification and quantification of 14 nucleosides and nucleobases, namely cytosine, uracil, cytidine, guanine, hypoxanthine, xanthine, uridine, thymine, inosine, guanosine, thymidine, 2′-deoxyadenosine, 2′-deoxyinosine and 2′-deoxyuridine in two traditional Chinese medicines, Geosaurus and Leech. The separation was achieved on a TSKgel Amide-80 column (150 mm × 2.0 mm, 3.0 μm) with a mixture of acetonitrile and 10 mM aqueous ammonium acetate as the mobile phase at a flow rate of 0.2 mL/min. The temperature was set at 30 °C and UV detection wavelength was set at 260 nm. All calibration curves showed good linearity (R² > 0.9957) within the test ranges. The overall intra- and inter-day RSD ranged from 0.4 to 3.4% and from 0.7 to 3.3%, respectively. The LOD and LOQ were in the range of 0.07-30.49 ng/mL and 0.26-60.98 ng/mL, respectively. The repeatability of the method was in the range of 2.2-5.8% for Geosaurus and 1.4-5.5% for Leech. The recoveries of the samples were in the range of 91.4-100.9% for Geosaurus, and 91.9-99.3% for Leech. The established method was applied successfully for the analysis of nucleosides and nucleobases in 22 commercially available samples collected from different regions in China and Japan. Our data showed that HILIC had advantages as a useful tool for the study of the bioactive components in Geosaurus and Leech as well as their quality control, and could therefore be used for the determination of the analytes in pharmaceutical products and biological fluids.     

Epitope prediction based on random peptide library screening: benchmark dataset and prediction tools evaluation

Epitope prediction based on random peptide library screening has become a focus as a promising method in immunoinformatics research. Some novel software and web-based servers have been proposed in recent years and have succeeded in given test cases. However, since the number of available mimotopes with the relevant structure of template-target complex is limited, a systematic evaluation of these methods is still absent. In this study, a new benchmark dataset was defined. Using this benchmark dataset and a representative dataset, five examples of the most popular epitope prediction software products which are based on random peptide library screening have been evaluated. Using the benchmark dataset, in no method did performance exceed a 0.42 precision and 0.37 sensitivity, and the MCC scores suggest that the epitope prediction results of these software programs are greater than random prediction about 0.09-0.13; while using the representative dataset, most of the values of these performance measures are slightly improved, but the overall performance is still not satisfactory. Many test cases in the benchmark dataset cannot be applied to these pieces of software due to software limitations. Moreover chances are that these software products are overfitted to the small dataset and will fail in other cases. Therefore finding the correlation between mimotopes and genuine epitope residues is still far from resolved and much larger dataset for mimotope-based epitope prediction is desirable.     

Strong solutions to 1D compressible Navier‐Stokes/Allen‐Cahn system with free boundary

This paper is concerned with a diffuse interface model for two‐phase flow of compressible fluids with a type of free boundary. We establish the existence and uniqueness of global strong solutions of a coupled Navier‐Stokes/Allen‐Cahn system in 1D.     

自锁模掺钛宝石激光器的泵浦研究

对自锁模掺钛宝石激光器的原理作了较详细的描述，指出克尔透镜效应是形成自锁模的主要原因，但是，只有将克尔透镜自聚焦、振荡光参数和泵浦光参数三者结合起来考虑，才能全面了解自锁模的形成过程，本文从速率方程出发，得出了激光介质增益与光束参数的相对变化曲线，并据此来优化自锁模钛宝石激光器的设计，最后，将计算结果与实验作了比较，两者符合得较好。     

流化床煤气化炉内脱硫的研究Ⅰ．台式流化床煤气化的炉内脱硫试验

采用台式流化床煤气化装置，研究了影响炉内脱硫效率的因素。炉内脱硫对高硫煤特别有效，脱硫效率可达９０％以上。所采用的二种石灰石和一种白云石脱硫效率相近，按Ｃａ／Ｓ比比较则白云石稍好些。虽然脱硫效率随Ｃａ／Ｓ比增加而增加，但当Ｃａ／Ｓ比达到３后几乎不再增加。存在一个最佳脱硫操作温度。在非焙烧区，脱硫率随压力增加而下降，而在焙烧区脱硫率和压力几乎无关。测定了脱硫剂脱硫前后的孔容积分布，发现脱硫之后１～３０ｎｍ的孔容显著减少。     

人工神经网络光度法用于化探样品中金的形态分析

利用人工神经网络对化探样品中金的三种存在形态（水提取态、吸附态、有机态）的含量同时进行了预测，计算结果与传统浸了方法的结果相吻合，相对误差一般小于10％，相对标准偏差在1．68％－8．94％。该法简便，快速。     

Ti:sapphire laser pumped high average power laser crystal Nd:GGG with high efficiency output

High-quality neodymium doped GGG laser crystals have been grown by Czochralski (Cz) method. Results of Nd:GGG thin chip laser operating at 1.064 μm pumped by Ti:sapphire laser operating at 808 nm were reported. The slop efficiency was as high as 20%.