I.I.D.随机变量两两乘积之和的Hsu-Robbins型定理(Ⅱ)

在本部分中,采用由 Ｌｅｖｙ函数（４．ｌ）所确定的值ｂｎ取代（Ｉ）［１］中的１／ｎ“位点”ａｎ,使得（Ｉ）中定理１中的附加条件（Ａ）得以解除,从而获得了可以称之为Ｈｓｕ－Ｒｏｂｂｉｎｓ型的充分必要条件．作为推论,还给出了两个互为复制的ｉｉｄ随机变量三角阵对应行之和乘积的Ｋｏｌｍｏｇｏｒｏｖ强大数律．     

A new water treatment technology for degradation of B[a]A by hydrodynamic cavitation and chlorine dioxide oxidation

Managing environmental contamination with Benz[a]anthracene (B[a]A) is essential due to its carcinogenic, teratogenic and mutagenic effects on humans and the environment. At present, the mainly B[a]A degradation methods used are photodegradation, bioremediation and traditional advanced oxidation, although they all have disadvantages. In this study, B[a]A was degraded by hydrodynamic cavitation (HC), chlorine dioxide (ClO₂), or an innovative combination of the two methods. According to high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC–MS) analysed the degradation products and degradation pathway of B[a]A, with the kinetics of different degradation methods discussed. Under optimal conditions, HC combined with ClO₂ oxidation can further degrade products to achieve ring cleavage. Compared with the two separate degradation process methods, the combined method exerts a synergistic effect on the degradation of B[a]A, with an enhancement factor of 1.48. Experimental results showed that the combination method can realize enhanced complete degradation of B[a]A, reduce ClO₂ requirements, improve efficiency, reduce energy consumption and produce less harmful products with ring cleavage achieved.     

The inverse M-matrix problem

One aspect of the inverse M-matrix problem can be posed as follows. Given a positive n × n matrix A=(a_ij) which has been scaled to have unit diagonal elements and off-diagonal elements which satisfy 0 < y ? a_ij ? x < 1, what additional element conditions will guarantee that the inverse of A exists and is an M-matrix? That is, if A^?1=B=(b_ij), then b_ii> 0 and b_ij ? 0 for i≠_j. If n=2 or x=y no further conditions are needed, but if n ? 3 and y < x, then the following is a tight sufficient condition. Define an interpolation parameter s via x²=sy+(1?s)y²; then B is an M-matrix if s^?1 ? n?2. Moreover, if all off-diagonal elements of A have the value y except for a_ij=a_jj=x when i=n?1, n and 1 ? _j ? n?2, then the condition on both necessary and sufficient for B to be an M-matrix.     

原子吸收法测定冶金物料中的镍

加入１９２０ｐｐｍ镧盐，即可在０．６ｍｏｌ／ＬＨ＿２ＳＯ＿４与Ｈ＿３ＰＯ＿４混合液中同时共存３０ｐｐｍ铜与铁及１５ｐｐｍ钴时，测定３０ｐｐｍ镍，相对误差＜５％。     

γ辐照三烷基氧膦中烷烃的顶空气相色谱法测定

建立了顶空气相色谱法测定γ辐照三烷基氧膦中微量轻质烃的方法。研究了色谱条件及顶空加热条件。方法的回收率为 90 %— 10 9% ,对正戊烷、正己烷、正辛烷的检出限分别为 8.7× 10 - 7、3.2× 10 - 6 、3.1× 10 - 5g/ m L。用于测定三烷基氧膦中轻质烃辐解产物得到满意的结果     

Formal synthesis of erythrodiene and spirojatamol via rhodium-catalysed Claisen rearrangement/hydroacylation

A novel procedure allows the synthesis of spiro[4.5]decane-1,6-dione 1, a key intermediate in the total synthesis of erythrodiene and spirojatamol. The key step is a combination of Claisen rearrangement of allyl vinyl ethers followed by an intramolecular hydroacylation catalysed by RhCl(cod)(dppe).     

国外聚烯烃树脂工艺进展及新产品开发

从生产技术和新品种开发方面介绍了国外烯烃树脂最新进展情况，指出茂金属催化剂技术，Ｃａｔａｌｌｏｙ技术，Ｓｐｈｅｒｉｌｅｎｅ技术是人们开发研究的重点，特别是茂金属催化剂技术能按照用户的要求“定制”不同结构的聚合物，茂金属催化剂技术为开发更多的高性能聚烯树脂提供了可能。     

Bioinspired Total Synthesis of Complex Nucleoside Antibiotics A201A,A201D and A201E

Herein, bioinspired total syntheses of A201A, A201D, and A201E based on a previously reported biosynthetic pathway are presented. The challenging 1,2-cis-furanoside, a core structure of the A201 family, was obtained by remote 2-quinolinecarbonyl-assisted glycosylation. We accomplished the total synthesis of A201A and A201E based on the critical 1,2-cis-furanoside moiety through late-stage glycosylation without any interference from basic dimethyl adenosine. We also confirmed the absolute configuration of A201E by total synthesis. This modular synthesis strategy enables efficient preparation of A201 family antibiotics, allowing the study of their structure–activity relationships and mode of action. This study satisfies the increasing demand for developing novel antibiotics inspired by the A201 family.     

Modular Oxime Formation by a trans-AT Polyketide Synthase

Modular trans-acyltransferase polyketide synthases (trans-AT PKSs) are enzymatic assembly lines that biosynthesize complex polyketide natural products. Relative to their better studied cis-AT counterparts, the trans-AT PKSs introduce remarkable chemical diversity into their polyketide products. A notable example is the lobatamide A PKS, which incorporates a methylated oxime. Here we demonstrate biochemically that this functionality is installed on-line by an unusual oxygenase-containing bimodule. Furthermore, analysis of the oxygenase crystal structure coupled with site-directed mutagenesis allows us to propose a model for catalysis, as well as identifying key protein-protein interactions that support this chemistry. Overall, our work adds oxime-forming machinery to the biomolecular toolbox available for trans-AT PKS engineering, opening the way to introducing such masked aldehyde functionalities into diverse polyketides.