A new approach for the formation of fused cyclooctane or cyclohexane rings

The intramolecular regioselective addition of unsymmetrical allylsilanes to conjugated dienones is shown to permit facile entry into 5-6, 6-6, 5-8, and 6-8 bicyclic ring systems.     

The structured sensitivity of Vandermonde-like systems

Summary We consider a general class of structured matrices that includes (possibly confluent) Vandermonde and Vandermonde-like matrices. Here the entries in the matrix depend nonlinearly upon a vector of parameters. We define, condition numbers that measure the componentwise sensitivity of the associated primal and dual solutions to small componentwise perturbations in the parameters and in the right-hand side. Convenient expressions are derived for the infinity norm based condition numbers, and order-of-magnitude estimates are given for condition numbers defined in terms of a general vector norm. We then discuss the computation of the corresponding backward errors. After linearising the constraints, we derive an exact expression for the infinity norm dual backward error and show that the corresponding primal backward error is given by the minimum infinity-norm solution of an underdetermined linear system. Exact componentwise condition numbers are also derived for matrix inversion and the least squares problem, and the linearised least squares backward error is characterised.     

Bi2Sr2CuO6的电子结构和铜氧对间电荷涨落

自发现含铋铜氧化物的高温超导性以来,采用各种复杂程度方法对电子结构的计算已经在文献中报道.它们集中讨论了能带结构,态密度和Fermi面的性质,但很少报道铜氧对间的电荷涨落。而价态变动对超导电性起着至关重要的作用,因此本文对Bi_2Sr_2CuO_6进行了紧束缚带计算,探讨了电子缺陷和氧呼吸式振动对铜和氧电荷分布的影响。     

Synthesis and Characterization of Transition Metal Methanesulfonates and their Catalytic Behavior in Biginelli Reactions

A series of transition metal methanesulfonates were prepared and characterized by FTIR and TG. Characteristic peaks for the methyl and sulfonyl groups were observed in the i.r. spectra. The number of crystal waters and the process of dehydration and decomposition were determined by TG. The catalytic behavior of transition metal methanesulfonates in Biginelli one-pot cyclocondensation of aldehydes, 1,3-dicarbonyl compounds and urea in absolute EtOH under refluxing temperatures was investigated. The products, 3,4-dihydropyrimidinones, were characterized by elemental analysis, ¹H n.m.r. and FTIR. The experimental results showed transition metal methanesulfonates were efficient for the Biginelli reaction.     

碱性介质中异丙醇在铂电极表面的吸附和电化学氧化

运用电化学循环伏安、原位FTIR反射光谱和石英晶体微天平(EQCM)等方法研究了碱性介质中异丙醇在Pt电极表面吸附和氧化行为. 结果表明：碱性介质中异丙醇电氧化过程不存在自毒化现象. 虽然电化学原位FTIR反射光谱未能检测到CO等毒性物种, 但EQCM结果证明异丙醇或其解离产物吸附于铂电极上. 在实验条件下, 碱性介质中异丙醇在铂电极上氧化的最终产物只有丙酮, 预示着碱性介质中异丙醇通过脱氢步骤氧化成丙酮. EQCM研究还从电极表面质量定量变化的角度提供了异丙醇吸附和电氧化反应机理的新数据.     

Thermal analysis of Australian coals—A short review

It is evident that thermal analysis studies of Australian coals are of primary significance in the rationalisation of the various physical and chemical processes inherent in energy generation from these fossil fuels. To data, considerable such data has been accumulated correlating combustion efficiency with the coal primary structure, surface phenomena, included metal ions, volatile matter release profiles, particle size and corresponding char properties. The kinetics of these complex processes are now also modelled.

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Zusammenfassung Für die Rationalisierung der physikalischen und chemischen Prozesse bei der Energiegewinnung aus australischer Kohle sind thermoanalytische Untersuchungen dieser fossilen Rohstoffe von erstrangiger Bedeutung. Es wurde eine bedeutende Menge von Angaben gesammelt, die eine Beziehung zwischen dem Verbrennungsgrad und der Primärstruktur der Kohle, Oberflächenerscheinungen, enthaltenen Metallionen, des Emissionsprofiles flüchtiger Verbindungen, der Partikelgröße und der entsprechenden Halbkokseigenschaften herstellen. Die Kinetik dieser komplexen Vorgänge wurde nun auch modelliert.

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The Future of Gas to Liquids as a Gas Monetisation Option

The paper introduces gas to liquids (GTL) as a monetising option from a technology, marketingand project perspective. GTL is complementary to LNG and pipelines. At the same time, using naturalgas as a source for fuels in the form of GTL helps countries around the world to diversify their energysupplies. Furthermore, gas-based products are inherently cleaner than oil products. Shell‘s proprietary GTL technology or SMDS (Shell Middle Distillates Synthesis), is discussed in some detail. The paperalso covers the challenges for successful implementation of GTL projects and why Shell is well positionedto take a lead in the industry on the basis of its long standing and broad experience in GTL research,plant operations, marketing and excellent track record in mega projects in the last thirty years. Shell‘scommitment to GTL is best demonstrated by the recent signing of a Heads of Agreement with Qatar Petroleum for the construction of the world‘s largest GTL plant. A key success factor is Shell‘s experiencewith marketing quantities of high quality GTL products from its 12,500 barrels per day plant at Bintulu,Malaysia since 1993. Further marketing opportunities will arise when new GTL capacity comes on-streamin the middle east when more quantities will become available to bulk users. Amongst the most interesting market will be automotive transportation, where clean GTL fuels can be positioned as an ‘alternativefuel beyond oil‘ providing energy security to host countries. Shell is actively engaging with a numberof regulators, automotive companies and governments worldwide including China, to demonstrate theperformance of GTL and its cost effectiveness in reducing local emissions. An added benefit is that GTLcan use existing infrastructure and requires no investment. Finally, the paper briefly discusses the coal toliquids (CTL) process as an alternative route to produce high quality GTL products and the key issuesrelating to the process.     

Flavonoid Glycosides from Ranunculus chinensis Bge.

Four new flavonoid glycosides, 3‐O‐[α‐L ‐arabinopyranosyl‐(1→2)‐β‐D ‐galactopyranosyl]‐7‐O‐β‐D ‐glucopyranosylkaempferol ( 1 ), 3‐O‐(α‐L ‐arabinopyranosyl‐(1→2)‐{4‐O‐[(E)‐caffeoyl]‐β‐D ‐galactopyranosyl})‐7‐O‐β‐D ‐glucopyranosylquercetin ( 2 ), 3‐O‐{2‐O‐[(E)‐caffeoyl]‐α‐L ‐arabinopyranosyl‐(1→2)‐β‐D ‐galactopyranosyl}‐7‐O‐β‐D ‐glucopyranosylkaemperfol ( 3 ), and 3‐O‐{2‐O‐[(E)‐caffeoyl]‐α‐L ‐arabinopyranosyl‐(1→2)‐β‐D ‐galactopyranosyl}kaempferol ( 4 ), together with two known compounds were isolated from the aerial parts of Ranunculus chinensis Bge . The structures of the new glycosides were determined on the basis of spectroscopic analysis, including 1D‐ and 2D‐NMR, and ESI‐MS techniques, and chemical methods.     

GC-ECD determination of cypermethrin and its major metabolites in soil, elm bark, and litter

An analytical method has been developed for the simultaneous determination of residues of four pairs of isomers of the pyrethroid insecticide cypermethrin, and their main metabolites, cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethyl-cyclopropanecarboxylic acid (CCA) and 3-phenoxybenzoic acid (PBA), in elm bark, litter, and soil in the control of elm bark beetles, the vector of the Dutch elm disease. The residues of cypermethrin isomers and their metabolites were extracted with methanol under acidic conditions from elm bark, litter, and soil, cleaned up with liquid-liquid partitioning, and chromatographed by GC-ECD together after the CCA and PBA in the sample had been derivatized with α-bromo-2,3,4,5,6-pentafluorotoluene. The average recoveries of cypermethrin isomer pairs were 82 to 112% with relative standard deviations (RSDs) of 2.3 to 10% at the fortification levels of 2, 10, 100 μg/g in elm bark, 2, 15, 150 μg/g in litter, and 0.2, 2, 20 μg/g in soil. The recoveries of cypermethrin metabolites were 83 to 107% with RSDs from 2 to 12% at the fortification levels of 0.5, 5, and 10 μg/g in elm bark, and litter, and 0.1, 1, and 10 μg/g in soil.