Applications of High-Resolution Mass Spectrometry in Studies of Brown Carbon

Brown carbon is a hotspot in the field of atmospheric carbonaceous aerosol research. It has significant influence on regional radiative forcing and exerts climatic effects due to its apparent absorbance in the near ultraviolet-visible region. Brown carbon is mainly derived from incomplete combustion of biomass or coal, as well as secondary sources, such as a series of atmospheric photochemical reactions from volatile organic compounds. Although the composition of brown carbon is complex, high-resolution mass spectrometry, with its ultra-high mass resolution and precision, enables elucidation of the characteristics of the organic components of brown carbon at the molecular level. Here, high-resolution mass spectrometry combined with traditional analytical methods was used for the study of brown carbon. The development of high-resolution mass spectrometry for brown carbon separation is reviewed, as well as compositional analysis, source apportionment, and formation mechanism of brown carbon based on high-resolution data. In addition, the issues and prospects for the application of high-resolution mass spectrometry to evaluate brown carbon are discussed.     

板栗壳棕色素的吸附树脂法精制

采用大孔吸附树脂分别对以水和乙醇为溶剂制得的板栗壳棕色素Ⅰ和色素Ⅱ进行精制,确定了色素Ⅰ以Ｄ４０２０,色素Ⅱ以ＮＫＡ－９为吸附剂,并对精制效果作了评价。本文为吸附树脂在色素中的应用提供一定的科学依据。     

Expedient synthesis of bisabolenol stink bug pheromones via stereodefined cyclohex-2-enones

We recently synthesized all stereoisomers of 1,10-bisaboladien-3-ol and 10,11-epoxy-1-bisabolen-3-ol, including three stink bug pheromones, via a rhodium-catalyzed asymmetric addition of trimethylaluminum to diastereomeric mixtures of cyclohex-2-enones. However, yields of trans isomers were low, and scaling reactions using expensive catalysts were cumbersome. Now we describe a new synthesis of bisabolenol stink bug pheromones via (S)- and (R)-4-((R)-6-methylhept-5-en-2-yl)cyclohex-2-enones prepared by enantioselective Michael additions of methyl vinyl ketone to (S)- and (R)-citronellals and lithium hydroxide monohydrate-catalyzed stereoselective cyclizations of intermediate ketoaldehydes. Addition of methyllithium to these enones provided cis- and trans-1,10-bisaboladien-3-ols, which were separated by chromatography on silica and further converted to 10,11-epoxy-1-bisabolen-3-ols. Thus, we developed more convenient syntheses of pheromones of the rice stink bug, the harlequin bug, and brown marmorated stink bug.     

Stereoselective synthesis of the C3-C15 fragment of callyspongiolide

The synthesis of C3-C15 fragment of callyspongiolide, a 14-membered macrolides isolated from the marine sponge Callyspongia sp., which was collected from the Indonesia, is reported. Highlights of the synthesis include construction of E-olefin through Julia-Kocienski olefination, Brown asymmetric allylation and base-induced elimination reactions for propargyl alcohol synthesis.     

BroWn-Broyden修正算法

1　引　　言求解非线性方程组F(x) =f1 (x1 ,… ,xn)廸n(x1 ,… ,xn)=0　　 F:D Rn→ Rn,(1.1)的 Brown方法 ,是将广义的 L U分解用于 Newton迭代过程 ,而形成的一类具有内外迭代形式的有效算法 .这类算法的特点是每步迭代的函数计算量仅仅为 Newton法的一半 ,而收敛速度则与 Newton法相同 .因此 ,按 Ostrowskii定义的效率指数去衡量 ,Brown方法为一效率较高的算法之一 ,是倍受推崇的 .本文 ,采用修正算法的思想 ,对 Brown方法作进一步改造 ,在不破坏原来的内外迭代形式下 ,使算法在每步迭代中的函数计值量由原来的 O(n2 )下降到 O(…     

Several extensions of the Abian–Brown Fixed Point Theorem and their applications to extended and generalized Nash equilibria on chain-complete posets

In this paper, we provide several extensions of the Abian–Brown Fixed Point Theorem from single-valued mappings to set-valued mappings on chain-complete posets. Then we examine some non-monetized, non-cooperative games where both the collections of the strategies and the ranges of the utilities for the players are posets. By applying the extensions of the Abian–Brown Fixed Point Theorem and by applying the order-preserving property of mappings, we prove some existence theorems of extended and generalized Nash equilibria for non-monetized, non-cooperative games on chain-complete posets.     

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本文考虑了常利力下带干扰的双复合Poisson风险过程, 借助微分和伊藤公式, 分别获得了无限时和有限时生存概率的积分微分方程. 当保费服从指数分布时, 得到了无限时生存概率的微分方程.     

A Conversation with Robert F. Christy – Part II

Robert F. Christy, Institute Professor of Theoretical Physics Emeritus at Caltech, recalls his wartime work at Los Alamos on the critical assembly for the plutonium bomb (“the Christy bomb”); the Alamogordo test, July 16, 1945; the postwar concerns of ALAS (Association of Los Alamos Scientists); his brief return to the University of Chicago and move to Caltech; friendship with and later alienation from Edward Teller; work with Charles and Tommy Lauritsen and William A. Fowler in Caltech’s Kellogg Radiation Laboratory; Freeman Dyson’s Orion Project; work on the meson and RR Lyrae stars; fellowship at Cambridge University; 1950s Vista Project at Caltech; his opposition to the Strategic Defense Initiative; and his post-retirement work for the National Research Council’s Committee on Dosimetry and on inertial-confinement fusion.     

Serre-duality for Tails

A version of Serre-duality is proved for Artin's non-commutative projective schemes.

     

股票市场价格波动的实证分析

利用几何布朗运动模型模拟一段时间内的股价波动并绘出其价格曲线，与实际的价格曲线相对照，发现股价波动直观上近似符合几何布朗运动。进一步进行严格的统计检验，结果表明几何布朗运动模型只能部分地描述我国股票市场的价格波动规律。