Analysis of ketones by selected ion flow tube mass spectrometry

A selected ion flow tube mass spectrometry (SIFT-MS) study of the reactions of H3O+, NO+ and O2+* ions with the ketones (M) 2-heptanone, 2-octanone, 2-nonanone, 2-undecanone and 2-aminoacetophenone has been conducted in preparation for studies of volatile emissions from bacteria. The H3O+ reactions all proceed rapidly via exothermic proton transfer, producing only MH+ ions that form their monohydrates when water vapour is present in the helium carrier gas. The O2+* reactions proceed rapidly via dissociative charge transfer producing parent cations M+* and some fragment ions. The NO+ reactions form the NO+M adduct ions at rates which are dependent on the pressure of the helium carrier gas. Combining the present NO+ kinetic data with those available from previous SIFT studies, the phenomenon of charge transfer complexing is clearly demonstrated. This results in adduct formation in these NO+/ketone reactions at or near the collisional rate. SIFT-MS spectra are presented to illustrate the simplicity of SIFT-MS analysis of ketones using both H3O+ and NO+ precursor ions.     

A consensus model of political decision-making

In this paper, a model of political consensus is introduced. Parties try to reach consensus in forming a government. A government is defined as a pair consisting of a winning coalition and a policy supported by this coalition, where a policy consists of policies on given issues. A party evaluates all governments the party belongs to with respect to some criteria. We allow the criteria to be of unequal importance to a party. These criteria concern winning coalitions and policy issues. Parties may be advised to adjust their preferences, i.e., to change their evaluation concerning some government(s) or/and the importance of the criteria, in order to obtain a better political consensus.     

选择离子流动管质谱对汽车尾气成分的分析

运用选择离子流动管质谱(SIFT／MS)装置,以H3O^ 、NO^ 、O2^ 为初始离子对安装有催化转换装置的汽油车引擎启动5min后的尾气进行了取样分析,结果表明,尾气中含有大量的C—H化合物(包括烷烃、烯烃、炔烃、二烯烃以及芳香烃),含氧有机物(包括醛、酮、醇)以及NH3和NOx等污染成分。其中,NO的含量最高,它的浓度比其它所有SIFT／MS装置所能测量到的各种物质的总和还多;在C—H化合物中以芳香烃的含量最高,约占整个C—H化合物含量的一半以上;在含氧有机物中以醛类物质的含量最高。初步讨论了这些成分的形成动力学过程,对引擎冷启动和热启动时的尾气成分进行了分析,结果表明：冷启动尾气中C—H化合物和NOx的含量是热启动的3—5倍,而含氧有机物的含量没有很大的变化,此结果也证明了尾气的催化转化装置是一种减少尾气中C—H化合物和NOx污染物的一种有效的控制方法。这也证明了SIFT／MS技术是一种有效的分析痕量有机污染物的方法。     

Analyser‐based tomography images of cartilage

Analyser‐based imaging expands the performance of X‐ray imaging by utilizing not only the absorption properties of X‐rays but also the refraction and scatter rejection (extinction) properties. In this study, analyser‐based computed tomography has been implemented on imaging an articular cartilage sample, depicting substructural variations, without overlay, at a pixel resolution of 3.6 µm.     

Double and negative reflection of cold atoms in non-Abelian gauge potentials

Atom reflection is studied in the presence of a non-Abelian vector potential proportional to a spin-1/2 operator. The potential is produced by a relatively simple laser configuration for atoms with a tripod level scheme. We show that the atomic motion is described by two different dispersion branches with positive or negative chirality. As a consequence, atom reflection shows unusual features, since an incident wave may split into two reflected ones at a barrier, an ordinary specular reflection, and an additional nonspecular one. Remarkably, the latter wave can exhibit negative reflection and may become evanescent if the angle of incidence exceeds a critical value. These reflection properties are crucial for future designs in non-Abelian atom optics.     

Post-treatment of Fungal Biomass to Enhance Pigment Production

Applied Biochemistry and Biotechnology - A new post-treatment method of fungal biomass after fermentation is revealed. The post-treatment strategy was utilized to produce pigments as an additional...     

In situ formation of ligand and catalyst--application in ruthenium-catalyzed enantioselective reduction of ketones

The direct in situ formation of highly efficient ruthenium-catalysts for the asymmetric reduction of ketones was obtained by combining chiral ligand building blocks with a ruthenium precursor.     

Novel simple and highly modular ligands for efficient asymmetric transfer-hydrogenation of ketones

Novel simple and highly modular dipeptide-analogue ligands combined with [RuCl2(p-cymene)]2 were demonstrated to efficiently catalyze the reduction of ketones under hydrogen transfer conditions with enantioselectivities up to 96%.