Analysing and modelling the performance of the HemeLB lattice-Boltzmann simulation environment

We investigate the performance of the HemeLB lattice-Boltzmann simulator for cerebrovascular blood flow, aimed at providing timely and clinically relevant assistance to neurosurgeons. HemeLB is optimised for sparse geometries, supports interactive use, and scales well to 32,768 cores for problems with ∼81 million lattice sites. We obtain a maximum performance of 29.5 billion site updates per second, with only an 11% slowdown for highly sparse problems (5% fluid fraction). We present steering and visualisation performance measurements and provide a model which allows users to predict the performance, thereby determining how to run simulations with maximum accuracy within time constraints.     

多芯片组件技术的发展及应用

简要介绍了多芯片组件(MCM)技术的概念、分类、发展现状、应用情况等.MCM是现代组装技术的新概念,它的出现促进了SMT(表面贴装技术)与SMD(表面贴装元器件)的发展和革新,并将成为高密度、高性能、多功能封装的最佳选择.     

Expert systems for chemical analysis (ESPRIT Project 1570)

Summary This paper gives an overview of the structure and processes going on in the project Expert Systems for Chemical Analysis (ESCA), an international project within the ESPRIT research programme of the European Community. The application area, HPLC method development, is explained and broken down into four domains. The methods used for representing knowledge in the project are discussed.     

Polysaccharide derivatives as chiral stationary phases in HPLC

Twenty different tris(phenylcarbamate)s of cellulose were synthesized and evaluated as chiral stationary phases for HPLC. Optical resolving power of the tris(phenylcarbamate)s depends on the substituents introduced on the phenyl groups. Optical resolving abilities of amylose tris(phenylcarbamate)s were also evaluated. In most cases, either cellulose tris(3,5-dimethylphenylcarbamate) or amylose tris(3,5-dimethylphenylcarbamate) exhibited the highest optical resolving ability. Aralkylcarba-mates such as benzyl- and 1-phenylethylcarbamates of cellulose and amylose were also tested as chiral stationary phases. (S)-1-Phenylethylcarbamate of amylose showed a high optical resolving power.     

The determination of atmospheric concentrations of the active ingredients of pesticide formulations by high-performance liquid chromatography

Summary Methods of sampling atmospheres contaminated by pesticides in factory and agricultural environments, and subsequent analysis by HPLC, are discussed. Air sampling is carried out using porous polymer or filter collection media, usually a 100 dm³ air volume is suitable. Detection limits with ultra-violet detection are in the range 0.1 to 10 g m^–3.Presented at the 14th International Symposium on Chromatography London, September, 1982     

高效液相色谱－荧光检测法测定蒽和荧蒽

采用高效液相色谱－荧光检测法测定多环芳烃化合物蒽和荧蒽。在Ｓｈｉｍ－ｐａｃｋＣＬＣ－ｐｈｅｎｙｌ柱上，以５０％的乙腈水溶液作流动相，１２ｍｉｎ内实现了两组分的同时分离测定。线性范围为０～８０μｇ／ｍＬ，检测限低于５０ｎｇ／ｍＬ，相对标准偏差小于１％。     

重组人干扰素—γ的凝胶色谱分离及其变性剂对分离结果的影响

使用十二烷基硫酸钠，盐酸胍和尿素三种不同的变性剂溶解基因重组人干扰素－Ｇａｍｍａ（ｒ－ＩＦＮ－γ）包含体，然后进行凝胶色谱分离。使用活性，电泳和高效疏水作用色谱三种方法，比较了三种变性剂对分离结果的影响，结果为：尿素溶解包含体后ｒ－ＩＦＮ－γ的分子量与杂质相差较大，盐酸胍溶解液经分离后ｒ－ＩＦＮ－γ比活最高，ＳＤＳ对ｒ－ＩＦＮ－γ的构象影响较大。     

Investigation of Symphytum cordatum alkaloids by liquid-liquid partitioning, thin-layer chromatography and liquid chromatography-ion-trap mass spectrometry

From the alkalised crude extract of Symphytum cordatum (L.) W.K. roots, pyrrolizidine alkaloids (PAs) were extracted as free tertiary bases and polar N-oxides in a merely one-step liquid-liquid partitioning (LLP) in separation funnel and subsequently pre-fractionated by preparative multiple-development (MD) thin-layer chromatography (TLC) on silica gel plates. In this way three alkaloid fractions of different polarities and retention on silica gel plates were obtained as: the most polar N-oxides of the highest retention, the tertiary bases of medium retention, and diesterified N-oxides of the lowest retention. The former fraction was reduced into free bases by sodium hydrosulfite and purified by LLP on Extrelut-NT3 cartridge. It was further analysed together with the two other fractions by high-performance liquid chromatography (HPLC)-ion-trap mass spectrometry with atmospheric pressure chemical ionization (APCI) interface on XTerra C₁₈ column using a gradient elution. Based on MSⁿ spectra, 18 various alkaloids have been tentatively determined for the first time in this plant as the following types of structure: echimidine-N-oxide (three diasteroisomers), 7-sarracinyl-9-viridiflorylretronecine (two diasteroisomers), echimidine (two diasteroisomers), lycopsamine (two diasteroisomers), dihydroechinatine-N-oxide, dihydroheliospathuline-N-oxide, lycopsamine-N-oxide (three diasteroisomers), 7-acetyllycopsamine-N-oxide, symphytine-N-oxide (two diasteroisomers) and 2″,3″-epoxyechiumine-N-oxide.