β-内酰胺类抗生素酶促合成新进展

β-内酰胺类抗生素的合成在制药工业中占据重要的地位, 相关的酶促合成方法研究备受关注; 酶促合成显著提高合成效率, 减少三废的排放, 是实现绿色合成的有效方法. 综述了近年来β-内酰胺类抗生素酶促合成研究的新进展, 包括一锅合成法、原位产物排出法、介质技术和酶固定化方法.     

On-channel base stacking in microchip capillary gel electrophoresis for high-sensitivity DNA fragment analysis

We evaluated a novel strategy for high-sensitivity DNA fragment analysis in a conventional glass double-T microfluidic chip. The microchip allows for a DNA on-channel concentration based on base stacking (BS) with a microchip capillary gel electrophoretic (MCGE) separation step in a poly(vinylpyrrolidone) (PVP) sieving matrix. Depending if low conductivity caused a neutralization reaction between the hydroxide ions and the run buffer component Tris+, the stacking of DNA fragments were processed in the microchip. Compared to a conventional MCGE separation with a normal electrokinetic injection, the peak heights of 50-2650-base pair (bp) DNA fragments on the MCGE-BS separation were increased 3.9-8.0-fold. When we applied the MCGE-BS method to the analysis of a clinical sample of bovine theileria after PCR reaction, the peak height intensity of the amplified 816-bp DNA fragment from the 18S rRNA of T. buffeli was enhanced 7.0-fold compared to that of the normal injection method.     

Sol-gel approach to in situ creation of high pH-resistant surface-bonded organic-inorganic hybrid zirconia coating for capillary microextraction (in-tube SPME)

A novel zirconia-based hybrid organic-inorganic sol-gel coating was developed for capillary microextraction (CME) (in-tube SPME). High degree of chemical inertness inherent in zirconia makes it very difficult to covalently bind a suitable organic ligand to its surface. In the present work, this problem was addressed from a sol-gel chemistry point of view. Principles of sol-gel chemistry were employed to chemically bind a hydroxy-terminated silicone polymer (polydimethyldiphenylsiloxane, PDMDPS) to a sol-gel zirconia network in the course of its evolution from a highly reactive alkoxide precursor undergoing controlled hydrolytic polycondensation reactions. A fused silica capillary was filled with a properly designed sol solution to allow for the sol-gel reactions to take place within the capillary for a predetermined period of time (typically 15-30 min). In the course of this process, a layer of the evolving hybrid organic-inorganic sol-gel polymer got chemically anchored to the silanol groups on the capillary inner walls via condensation reaction. At the end of this in-capillary residence time, the unbonded part of the sol solution was expelled from the capillary under helium pressure, leaving behind a chemically bonded sol-gel zirconia-PDMDPS coating on the inner walls. Polycyclic aromatic hydrocarbons, ketones, and aldehydes were efficiently extracted and preconcentrated from dilute aqueous samples using sol-gel zirconia-PDMDPS coated capillaries followed by thermal desorption and GC analysis of the extracted solutes. The newly developed sol-gel hybrid zirconia coatings demonstrated excellent pH stability, and retained the extraction characteristics intact even after continuous rinsing with a 0.1 M NaOH solution for 24 h. To our knowledge, this is the first report on the use of a sol-gel zirconia-based hybrid organic-inorganic coating as an extraction medium in solid phase microextraction (SPME).     

紫外预电离TEA CO2激光器放电特性的实验研究

 横向激励大气压（transversely excited atmospheric,TEA）CO₂激光器的放电稳定性是决定该类型激光器应用效果的关键因素。通过对采用电感充放电电路的紫外预电离激光器的实验研究，得到了激光器放电动态过程的规律，并发现残余振荡是主放电后发生弧光放电的主要原因。实验中采用不同配比的气体，并对电感充放电电路与改进后的硅堆充放电电路进行了比较。实验结果表明：增加充电电感值可以降低主放电结束后储能电容上的残余电压；而采用硅堆放电电路在主放电后仅有相对幅值很低的稳定残压，两种方案都大幅度抑制了弧光放电的形成，有效地提高了激光单脉冲能量。     

神光-Ⅱ装置三倍频实验中靶场单元技术的改进

 主要介绍为了满足神光-Ⅱ高功率激光装置三倍频光（351nm，3ω）的物理实验要求，靶场三倍频模拟光源和瞄准监视系统两个主要单元技术的改进，即三倍频模拟光源由基频光（1 053nm，3ω）通过腔外的KTP+BBO晶体倍频获得，再经八路分光系统和主激光耦合；瞄准监视系统由透射式光学系统改进为反射式光学系统，避免原系统存在较大的色差，提高瞄准精度。     

过硫酸盐活化高级氧化新技术

过硫酸盐在热、光、过渡金属催化等条件激活下产生强氧化性的硫酸根自由基·SO₄^-。基于·SO₄^-的过硫酸盐活化“高级氧化技术”在环境污染治理领域的应用,是刚刚发展起来的崭新的研究方向,具有广阔的应用前景。本文在分析其基本原理的基础上,综述了过硫酸盐活化技术在国内外土壤地下水有机污染原位修复、难降解有机废水处理等环境污染治理方面的研究进展,并就存在问题进行了研究展望。     

基于微量热法的板蓝根提取方法和活性部位挑选

应用TAM Air微量热系统, 采用微量热法, 考察不同提取方法的板蓝根水煎液及其化学萃取部位在37 ℃时, 对大肠杆菌生长代谢的影响. 结合中医药理论, 分析板蓝根水煎液及其化学萃取部分的药效作用及其差异, 挑选板蓝根药材最佳的提取方法和抑菌最强的活性部位, 并采用试管稀释法求出抑菌活性最强部位的最小抑菌浓度(MIC). 结果表明微量热法可用于常用中药——板蓝根的提取方法和活性部位的挑选, 为进一步研究中药的药性基础提供了一种新的、快速灵敏的技术和方法.     

一步制备高比表面积介孔Co3O4-CeO2及其表征(英文)

以有序介孔二氧化硅KIT-6为硬模板,硝酸钴、硝酸铈为金属源,分别在真空辅助条件和普通搅拌条件下制备了介孔CoCeO_x复合氧化物。采用XRD、SEM、TEM、N₂吸脱附等技术表征了复合氧化物的物化性质,并评价其氧化甲苯的性能。结果表明,在真空辅助和搅拌条件下制备的CoCeO_x氧化物是由Co₃O₄和CeO₂组成的介孔Co₃O₄-CeO₂复合氧化物,其比表面积分别为141和89 m²·g^-1,平均孔径分别为8.7和9.6 nm。真空辅助纳米复制过程有利于金属盐的前驱体充分填充到模板的孔隙中,去除模板后,可以得到有序的介孔复合金属氧化物。所制备介孔钴铈复合氧化物具有孔道有序性好、比表面积大的特点,在挥发性有机化合物的氧化去除方面具有一定的应用前景。     

丙二醇甲醚中超痕量金属杂质元素的ICP-MS/MS分析

基于电感耦合等离子体串联质谱(ICP-MS/MS)建立了准确测定丙二醇甲醚中超痕量金属杂质元素的分析方法,提出了利用混合反应气消除质谱干扰的新策略.丙二醇甲醚经超纯水稀释后直接采用IC P-MS/MS测定其中具有挑战性的超痕量金属元素Mg,Al,K,Ti,V,Cr,Fe,Ni,Cu和Zn,在MS/MS模式下,选择混合气...     

Non-Destructive Detection of Moldy Walnuts Based on Hyperspectral Imaging Technology

Walnuts with their shells are a popular agricultural product in China. However, mildew from growth can sometimes be processed into foods. It is difficult to visually determine which walnuts have mildew without breaking the shells. A non-destructive method for detecting walnuts with mildew was studied by combining spectral data with image information. A total of 120 “Lüling” walnuts with shells were used for the mildew experiment. The characteristics of the spectral data from six surfaces of all samples were collected in the range of 370–1042 nm on days 0, 15, and 30. The spectrum was pretreated using SNV, and the feature bands were extracted using PCA and modeled using a support vector machine (SVM). The results show that the overall classification accuracy was 93%, with an of accuracy of 100% for INEN walnuts (normal internally and externally). The accuracy for IMEM walnuts (mildew internally and externally) reached 87.29%. There was an accuracy of 78.6% for IMEN walnuts (mildew internally and normal externally). The non-destructive detection of mildewed walnuts can be undertaken using hyperspectral imaging technology, which provides a new technique for exploring the mechanisms of walnuts with mildew.