Microwave digestion of hardly dissoluble samples

This paper describes a method for digestion of hardly dissoluble samples such as soil, sand, glass fiber and cellulose filters via microwave. The evaluation of this method was conducted by automatic TDCR liquid scintilation counter Hidex 300 SL. The alpha tracer ²⁴⁴Cm was used for the assessment of efficiency. The decomposition of samples was realized by MWS 4 Speedwave (Berghof, Germany) with the method determined to be simple, safe and very effective as evidenced by high chemical yield.     

Comparison of liquid-liquid partition, HS-SPME and static HS GC/MS analysis for the quantification of (-)-linalool in human whole blood samples

The aim of this investigation was to develop a fast and convenient method for the determination of (-)-linalool in human whole blood to facilitate pharmacokinetic studies. Analytical protocols were elaborated for three different GC/MS sampling techniques, i.e., static headspace (s-HS), headspace solid phase micro extraction (HS-SPME), and liquid-liquid partition. In principle, all tested methods were feasible, but s-HS had the greatest benefit because of the easy handling of the blood samples and its short analysis time. For s-HS two different incubation temperatures were tested (40 degrees C and 60 degrees C). The limit of detection was slightly lower when samples were incubated at 60 degrees C, but the same quantitative results were achieved using alpha-terpineol as internal standard. An accurate and sensitive method for the quantification of (-)-linalool in blood samples after either inhalation or percutaneous application, as well as pharmacokinetic data are presented.     

Bending analyses of 1D orthorhombic quasicrystal plates

The meshless Petrov–Galerkin method (MLPG) is applied to plate bending analysis in 1D orthorhombic quasicrystals (QCs) under static and transient dynamic loads. The Bak and elasto-hydrodynamic models are applied for phason governing equation in the elastodynamic case. The phason displacement for the orthorhombic QC in the first-order shear deformation plate theory depends only on the in-plane coordinates on the mean plate surface. Nodal points are randomly distributed over the mean surface of the considered plate. Each node is the center of a circle surrounding this node. The coupled governing partial differential equations are satisfied in a weak-form on small fictitious subdomains. The spatial variations of the phonon and phason displacements are approximated by the moving least-squares (MLS) scheme. After performing the spatial MLS approximation, a system of ordinary differential equations (ODEs) for nodal unknowns is obtained. The system of the ODEs of the second order is solved by the Houbolt finite-difference scheme. Our numerical examples demonstrate clearly the effect of the coupling parameter on both static and dynamic phonon/phason deflections.     

A GENERAL ALGORITHM FOR CALCULATING NEARLY SINGULAR INTEGRALS OVER HIGH-ORDER ELEMENTS IN 3D BEM

三维边界元分析中,高阶几何单元上的几乎奇异积分计算是一个重要而且困难的问题,该文对此进行了研究。使用8节点四边形和6节点三角形曲面单元来描述几何边界;构造了新的距离函数;拓展原有的指数函数非线性变换到三维边界元法中,利用拓展的变换来消除被积函数的几乎奇异性。数值算例表明,该算法稳定,效率高,即使计算点到实际边界的距离很小,依然可获得令人满意的数值解。     

Autoanalyzer-System zur qualitativen und quantitativen Bestimmung von Phosphonsäuren

Analytical and Bioanalytical Chemistry - Zur Bestimmung von Phosphonsäuren wurde ein Analysensystem entwickelt, das nach dem Prinzip der kontinuierlichen Durchflußanalyse arbeitet. Die im...     

Contour integrals for mixed-mode crack analysis: effect of nonsingular terms

An integral formulation for computing the nonsingular stresses (NSS) in a cracked body under mixed-mode static and dynamic loads is presented. The reciprocity theorems are applied to find the integral formula. The auxiliary fields are selected to eliminate the singular terms in the asymptotic expansion of the stresses near the crack tip. For elastodynamic crack problems, the integral representation of the NSS is presented in both the time and Laplace transform domain. Required variables along the integration path and region enclosed by the integration contour are obtained from the boundary element analysis. Influence of the NSS on predicting the crack growth direction is investigated for cracks under mixed-mode load conditions.     

Influence of growth temperature on the selective area MOVPE of InAs nanowires on GaAs (1 1 1) B using N2 carrier gas

The influence of temperature on selective area (SA) InAs nanowire growth was investigated for metal-organic vapor phase epitaxy (MOVPE) using N₂ as the carrier gas and (1 1 1) B GaAs substrates. In contrast to the growth temperature range – below 600 °C – reported for hydrogen ambient, the optimal growth temperature between 650 and 700 °C was 100 K higher than the optimal ones for H₂ carrier gas. At these temperatures, nanowires with aspect ratios of about 80 and a symmetric hexagonal shape were obtained. The results found are attributed to the physical and chemical properties of the carrier gas.     

Denaturation mapping of Saccharomyces cerevisiae

Optical mapping of DNA provides large-scale genomic information that can be used to assemble contigs from next-generation sequencing, and to detect rearrangements between single cells. A recent optical mapping technique called denaturation mapping has the advantage of using physical principles rather than the action of enzymes to probe genomic structure. Denaturation mapping uses fluorescence microscopy to image the pattern of partial melting along a DNA molecule extended in a channel of cross-section 120 nm at the heart of a nanofluidic device. We used denaturation mapping to locate single DNA molecules on the yeast genome (12.1 Mbp) by comparing images to a computationally predicted map for the entire genome sequence. By locating 84 molecules we assembled an optical map of the yeast genome with > 50% coverage.     

Catalytic C-F activation of polyfluorinated pyridines by nickel-mediated cross-coupling reactions

The cross-coupling reaction of pentafluoropyridine with tributyl(vinyl)tin affording 2-vinyltetrafluoropyridine by activation of a carbon-fluorine bond is catalysed by [NiF(2-C5NF4)(PEt3)2]; a similar reaction is observed with 2,3,5,6-tetrafluoropyridine.