Effect of Liposome Size on Internal RNA Replication Coupled with Replicase Translation

Cell membranes inhibit the diffusion of intracellular materials, and compartment size can strongly affect the intracellular biochemical reactions. To assess the effect of the size of microcompartments on intracellular reactions, we constructed a primitive cell model consisting of giant liposomes and a translation‐coupled RNA replication (TcRR) system. The RNA was replicated by Qβ replicase, which was translated from the RNA in giant liposomes encapsulating the cell‐free translation system. A reporter RNA encoding the antisense strand of β‐glucuronidase was introduced into the system to yield a TcRR read‐out (green fluorescence). We demonstrate that TcRR was hardly detectable in larger liposomes (230 fL) but was more effective in smaller (7.7 fL) liposomes. Our experimental and theoretical results show that smaller microcompartments considerably enhance TcRR because the synthesized molecules, such as RNA and replicases, are more concentrated in smaller liposomes.     

富马酸亚铁快速定性分析方法的探讨

针对富马酸的将点,利用纸上层析法以磷酸为溶剂测定富马酸亚铁中的富马酸,其检测结果可靠,检测方法重复性好,操作简捷,检测实验所需设备简单,成本低。此法能够简单而有效地对富马酸进行定性分析,实用性较强,尤其适用于中小饲料企业或市场监督部门对以富马酸亚铁为添加剂、补血剂的饲料产品进行鉴别。     

用于体液肽表达谱分析的快速肽段提取方法

目的探讨基于ZipTipC18的肽段提取方法在疾病临床诊断中的应用价值。方法用基于ZipTipC18和磁珠的体液肽段提取方法分别提取正常胰液、胰腺癌胰液和正常血液中的肽段,进行体液肽表达谱的PMF分析,对所得数据进行标准化处理,对目的肽段进行TOF/TOF分析鉴定。结果通过质谱分析得到了反映样品蛋白构成的肽表达谱。基于ZipTipC18的肽段提取方法获得的数据准确、可靠,重复较好,通过TOF/TOF分析,血液样品中的肽段鉴定为fibrinogen α链前体。根据正常胰液与胰腺癌胰液的差异肽表达谱,可将癌症患者与正常对照者明显区分。结论基于ZipTipC18的肽段提取方法可作为疾病(尤其是癌症)的辅助诊断方法。     

探析316L试板晶间腐蚀试验方法

通过试验证明了316L焊接接头做晶间腐蚀时,经常会由于熔敷金属塑性不足而发生焊缝开裂或断裂,影响了正常的试验过程与结果评判;并对GB／T4334．5提出补充建议。     

Allosteric Probe Recognition Initiated Cascade Transcription Amplification for Sensitive Analysis of Exosomes

Sensitive and accurate analysis of exosomes is important for many biological processes including as a biomarker for cerebral venous thrombosis (CVT) diagnosis and therapy. Herein, we established a sensitive and specific exosome detection approach based on target recognition initiated cascade signal amplification. In this method, an allosteric probe was designed with a hairpin structure for specific recognition of the exosome followed by signal amplification. After the cascade signal amplification process, spinach RNA sequences bind to DFHBI ((Z)-4-(3,5-difluoro-4-hydroxybenzylidene)-1,2-dimethyl-1H-imidazol-5(4H)-one) to produce enhanced fluorescence signal (approximate 2000 fold than that of inactive DFHBI). Compared with former proposed exosome detection techniques, this method exhibited a comparable detection range, but with an easy-to-design toolbox. Therefore, we believe that the proposed approach holds great potential for exosome based early diagnosis and prognosis of disease.     

The Generation of a Reduced Mechanism for Flame Inhibition by Phosphorus Containing Compounds Based on Path Flux Analysis Method

In order to analyze the complex chemical kinetic mechanism systematically and find out the redundant species and reactions, a numerical platform for mechanism analysis and simplification is established basing on Path Flux Analysis （PFA）. It is used to reduce a detailed mechanism for flame inhibited by phosphorus containing compounds, a reduced mechanism with 65 species and 335 reactions is obtained. The detailed and reduced mechanism are both used to calculate the freely-propagating premix C3H8/air flame with different dimethyl methylphosphonate doped over a wide range of equivalence ratios. The concentration distributions of free radicals and major species are compared, and the results under two different mechanisms agree well. The laminar flame speed obtained by the two mechanisms also matches well, with the maximum relative error introduces as a small value of 1.7%. On the basis of the reduced mechanism validation, the correlativity analysis is conducted between flame speed and flee radical concentrations, which can provide information for target species selection in the further mechanism reduction. By analyzing the species and reactions fluxes, the species and reaction paths which contribute the flame inhibition significantly are determined.     

DNA Polymerase Action on Oligonucleotide Templates from Human Ha-ras Protooncogene Containing N6-Deoxyadenosine Adducts Derived from Trans Addition of (+)- and (-)-anti-Benzo[c]phenanthrene-3,4-dihydrodiol 1,2-epoxides at Codon 61

In the present work we have used a DNA polymerase assay to investigate the primer extension with T7 DNA polymerase (Sequenase 2.0) and the Klenow fragment of Escherichia coli DNA polymerase I (exo ^? KF) on chemically synthesized 21mer templates representing partial sequences of the human Ha-ras protooncogene with site-specifically positioned trans-N ⁶-dA adducts of (-)- (adduct 1) and (+)-anti-benzo[c]phenanthrene 3,4-dihydrodiol 1,2-epoxides (adduct 2) at codon 61 (CA?G; A? indicates the adducted position). With Sequenase 2.0 a complete block of primer extension opposite both adduct 1 and 2 was noted using a 10mer primer reaching the (n-1)-position of the adduct. A detailed analysis revealed that Sequenase 2.0 exclusively allowed the misincorporation of dAMP opposite both adducts. In contrast, exo ^? KF allowed a significant full-length extension of the primer beyond adduct 2, whereas this process occured only to a very minor extent for adduct 1. Correspondingly, a more intensive block of the polymerization reaction opposite adduct 1 was seen. Analysis of the arrest bands revealed that dAMP was preferentially incorporated opposite to adduct 1; also incorporation of dGMP was observed, but to a minor extent. Similarly, dAMP was also incorporated opposite to adduct 2 along with dTMP, the latter indicating a correct base pairing. Additional experiments with exo ^? KF using different 11mer primers containing each of the four nucleotides opposite the adduct suggest that the primer extension beyond adduct 2 observed with the 10mer primer is an error-free process.     

A Comparative Study on the Catalytic Activity of Mn Containing MCM-41 Molecular Sieves for Oxidation of p-Cymene

Mesoporous silica molecular sieves SiMCM-41, AlMCM-41 with Si/Al ratio equal to 158 and MnMCM-41 with Si/Mn ratio equal to 29 were synthesized by hydrothermal method. Manganese oxide impregnated on SiMCM-41 and on AlMCM-41 catalysts were also prepared by wet impregnation method. These catalysts referred as Mn/SiMCM-41 and Mn/AlMCM-41 (158). Both the manganese incorporated and impregnated catalysts structure was elucidated by XRD. Nitrogen adsorption isotherm was used to determine specific surface area, pore volume, and pore size distribution. The thermal stability of the as-synthesized catalyst was studied using TG-DTA. The presence of Mn²⁺ was evident through DR UV–VIS and ESR spectroscopy. Through ESR studies, MnMCM-41 (29) was assigned to have framework Mn(II) sites. Extra-framework manganese species with well-resolved sextet, centered at g = 2.00 had octahedral symmetry was observed in Mn/SiMCM-41 and Mn/AlMCM-41 (158). Mn retained its +2 oxidation state (ESR active) even upon calcination at 550 °C in presence of air. The catalytic activity of the above-mentioned manganese containing MCM-41 catalysts were tested by vapor phase oxidation of p-cymene with CO₂-free air in the temperature range from 200 to 400 °C in steps of 50 °C. The major products were 4-methylacetophenone (4-MAP), 4-isopropyl benzaldehyde (4-IPB), 1,2-epoxyisopropyl benzaldehyde or 1,2-epoxycumenaldehyde (1,2-ECA) and 4-methyl styrene (4-MS). Among the product selectivity, (4-MAP) was found to be higher than that of others. The order of the activity of catalysts followed Mn/SiMCM-41 > Mn/AlMCM-41 (158) > MnMCM-41 (29) > Mn/SiO₂.     

Development of an Ultraviolet‐Spectrophotometric Method for Analysis of Esterquat‐Containing Flotation Collectors in Aqueous Solutions

In this study, a rapid and simple ultraviolet‐spectrophotometric method was developed and validated for the quantitative determination of esterquat‐containing flotation collector FLOT 2015 in aqueous solutions. This method is based on the formation of an ion pair by FLOT 2015 and bromocresol purple, an anionic dye, and the subsequent measurement of the reduction in absorbance without extraction by organic solvents. The optimum conditions for FLOT 2015 detection and analysis were established. Sample solutions were stable up to 3 h. Maximum absorbance was obtained at 574 nm. The proposed method showed linearity in the range of 5–45 μg mL^?1 with a correlation coefficient of 0.9917. Standard and relative standard deviation obtained by intraday and interday precision tests of the proposed method were within the permissible bias range and considered satisfactory. This method was found to be selective and specific for successful determination of FLOT 2015 in aqueous flotation systems.     

多裂纹压力容器剩余疲劳寿命计算方法研究

在考虑容器局部互扰裂纹（短裂纹群）对主裂纹（主导裂纹）扩展速率的影响后,精确计算了容器剩余疲劳寿命。通过实例验算,该方法适合工程要求。     

赛克津分析方法的研究

本文介绍了三氮苯类除草剂－赛克津的气相色谱法和高效液相色谱法的分析方法。认为此两法均可作为赛克津的检测方法。     

基于综合平衡法的RHCM成型LCD电视机前面壳工艺优化研究

在综合利用正交实验法、CAE分析和数据处理技术的基础上,对快速冷热成型技术（RHCM）成型LCD电视机前面壳成型工艺进行了优化研究。通过实验设计及数值模拟获得样本数据,结合方差分析技术确定了该产品各成型品质指标的显著性影响因素;进而通过级差分析和综合平衡分析研究得出了该产品的最佳工艺因素组合,并经实验验证了该优化组合的工艺可行性。     

高速剪切机浮动送料机构的运动学分析

提出了满足送料机构平动要求的平行四边形浮动送料机构,对浮动送料机构进行了结构设计,利用矩阵理论对其进行了运动学分析,建立了从动件的位置参数矩阵,从而利用现有的标准计算机程序进行求解,对机构进行了优化设计.     

用气液色谱法测定三元系中挥发组分有限浓度时活度系数的研究

本文研究了用色谱方法测定三元系中二个挥发组分在有限浓度时的活度系数,提出了实验规程及导出了用色谱数据计算活度系数的公式。测定了(1)苯-环己烷-邻苯二甲酸二壬酯(DNP)在40℃、60℃时,(2)苯-环己烷-角鲨烷(SQ)在60℃、80℃时二个体系中挥发组分(苯及环己烷)的活度系数。