PROZA and CALIBRATION CURVES for Quantitative X-Ray Microanalysis of Biological Samples

The main scope of our work was to investigate the usefulness of the PROZA correction method and CALIBRATION CURVE construction for quantitative X-ray microanalysis of biological soft, freeze-dried tissues. The test samples with a known elemental concentration of NaCl, MgCl₂, KH₂PO₄ and Na₂SO₄ were prepared on the basis of 20% porcine skin gelatine. A control sample containing 20% gelatine was used for sulphur subtraction. Dissolved gelatine solutions were cooled with liquid nitrogen and then cut in cryomicrotome into 16µm thick slices. The sections were lyophilised, coated with carbon and analysed by means of a scanning electron microscope combined with an energy dispersive (ED) spectrometer. The homogeneity of the prepared samples was verified using the Fishers test. Only homogenous samples were used for calibration. The significance of the (z) (PROZA) correction method for biological sample analysis was verified by comparing the prepared standard and entering it into the Voyager computer program memory with the remaining samples of a known elemental content. The differences between the standard and the samples were noted for all elements analysed. There was no sample matching the standard after the PROZA correction procedure. A high correlation r factor (above 0.99) for all analysed elements indicates that CALIBRATION CURVES construction could be suitable for quantitative X-ray microanalysis of biological samples.     

Study on the NaNp/CpTiCl3/Al2O3-SiO2 system

CpTiCl(3)/Al(2)O(3)-SiO(2)/NaNp (Cp=cyclopentadienyl, Np=naphthenide anion) system was obtained by a reduction of cyclopentadienyl titanium[IV] complexes supported on alumina-silica gels with sodium naphthenide in dinitrogen or argon atmospheres. The yield of the reduction reactions and the yield of dinitrogen fixation by the systems reduced in dinitrogen depend on the kind of phases which are present on alumina-silica gel surfaces according to their composition. On hydrolysis the nitrogen titanium complexes obtained liberated ammonia. The highest yields of these reactions, above 70% calculated as NH(3)/Ti ratio, were obtained for the systems containing in the carriers 10-, 60-wt%, of Al(2)O(3) and SiO(2Deg) of aerosil type. This relatively high activity was achieved with surface titanium complexes obtained by a reaction of CpTiCl(3) with isolated surface hydroxyl groups of neutral properties present on these gels. The EPR method was used to investigate the titanium[III] complexes formed during reduction of the systems. The signals obtained helped in discussion concerning the way in which titanium complexes undergo transformations during the reactions studied.     

Investigations of polyaniline-platinum composites prepared by sodium borohydride reduction

Two procedures were applied for the preparation of polyaniline (PANI)-Pt composites in aqueous solutions using sodium borohydride as the reducing agent. The first one involved reduction of Pt ions originating from PtCl₄ conducted in the presence of PANI. The second was a two-step method in which doping of PANI with Pt-containing anions was followed by their reduction. The composites containing various amounts of Pt were obtained. They were characterized by X-ray diffraction, X-ray photoelectron and IR spectroscopies. This allowed to establish differences in the efficiency of both methods of composite preparation. It was also found that the composites show mainly redox activity in catalytic isopropyl alcohol conversion.     

Numerical Studies of Vanka-Type Smoothers in Computational Solid Mechanics

In this paper multigrid smoothers of Vanka-type are studied in the context of Computational Solid Mechanics (CSM). These smoothers were originally developed to solve saddle-point systems arising in the field of Computational Fluid Dynamics (CFD), particularly for incompressible flow problems. When treating (nearly) incompressible solids, similar equation systems arise so that it is reasonable to adopt the 'Vanka idea' for CSM. While there exist numerous studies about Vanka smoothers in the CFD literature, only few publications describe applications to solid mechanical problems. With this paper we want to contribute to closing this gap. We depict and compare four different Vanka-like smoothers, two of them are oriented towards the stabilised equal-order $Q_1/Q_1$ finite element pair. By means of different test configurations we assess how far the smoothers are able to handle the numerical difficulties that arise for nearly incompressible material and anisotropic meshes. On the one hand, we show that the efficiency of all Vanka-smoothers heavily depends on the proper parameter choice. On the other hand, we demonstrate that only some of them are able to robustly deal with more critical situations. Furthermore, we illustrate how the enclosure of the multigrid scheme by an outer Krylov space method influences the overall solver performance, and we extend all our examinations to the nonlinear finite deformation case.     

An efficient and stable finite element solver of higher order in space and time for nonstationary incompressible flow

In this paper, we present fully implicit continuous Galerkin–Petrov (cGP) and discontinuous Galerkin (dG) time‐stepping schemes for incompressible flow problems which are, in contrast to standard approaches like for instance the Crank–Nicolson scheme, of higher order in time. In particular, we analyze numerically the higher order dG(1) and cGP(2) methods, which are super convergent of third, resp., fourth order in time, whereas for the space discretization, the well‐known LBB‐stable finite element pair of third‐order accuracy is used. The discretized systems of nonlinear equations are treated by using the Newton method, and the associated linear subproblems are solved by means of a monolithic (geometrical) multigrid method with a blockwise Vanka‐like smoother treating all components simultaneously. We perform nonstationary simulations (in 2D) for two benchmarking configurations to analyze the temporal accuracy and efficiency of the presented time discretization schemes w.r.t. CPU and numerical costs. As a first test problem, we consider a classical ‘flow around cylinder’ benchmark. Here, we concentrate on the nonstationary behavior of the flow patterns with periodic oscillations and examine the ability of the different time discretization schemes to capture the dynamics of the flow. As a second test case, we consider the nonstationary ‘flow through a Venturi pipe’. The objective of this simulation is to control the instantaneous and mean flux through this device. Copyright © 2013 John Wiley & Sons, Ltd.     

Complexes of dicamba with cadmium(II), copper(II), mercury(II), lead(II) and zinc(II)

New solid complexes of a herbicide known as dicamba (3,6-dichloro-2-methoxybenzoic acid) with Pb(II), Cd(II), Cu(II) and Hg(II) of the general formula M(dicamba)₂·xH₂O (M=metal, x=0-2) and Zn₂(OH)(dicamba)₃·2H₂O have been prepared and studied. The complexes have different crystal structures. The carboxylate groups in the lead, cadmium and copper complexes are bidentate, chelating, symmetrical, in Hg(dicamba)₂·2H₂O - unidentate, and in the zinc salt - bidentate, bridging, symmetrical. The anhydrous compounds decompose in three stages, except for the lead salt whose decomposition proceeds in four stages. The main gaseous decomposition products are CO₂, CH₃OH, HCl and H₂O. Trace amounts of compounds containing an aromatic ring were also detected. The final solid decomposition products are oxychlorides of metals and CuO. This revised version was published online in July 2006 with corrections to the Cover Date.     

Study on the Incorporation of Oat and Yeast β-Glucan into Shortbread Biscuits as a Basis for Designing Healthier and High Quality Food Products

According to international health and food organizations and authorities, people should limit fat intake since fat is the most caloric component of food and it is often a source of unsafe saturated fatty acids (FA) and trans isomers. The greatest health benefits come from replacing shorts with dietary fiber molecules. The aim of the study was to determine the possibility of reducing shortening content, which has an undesirable profile of FA, by addition of β-glucan molecules in shortbread biscuits. The effect of oat and yeast β-glucan supplementation on physical and sensory quality of products with reduced fat content (max 15%) were studied. It was shown that the substitution of shortening by β-glucan in shortbread biscuits is possible to a limited extent. Reduction in product energy value (up to 36 kcal/100 g) and content of undesirable FA (maximum 2.1 g/100 g) and increased of β-glucan content, regardless of the type, caused deterioration of biscuits quality and affected changes during storage. The substitution of shortening by β-glucan in food is a good way to improve nutritional value by increasing the amount of dietary fiber molecules, reducing calories, and amount of SFA in diets.     

High Performance Computing Techniques for the FEM Simulation in Structural Mechanics

For the solution of large scale simulations in structural mechanics iterative solving methods are mandatory. The efficiency of such methods can crucially depend on different factors: choice of material parameters, quality of the underlying computational mesh and number of processors in a parallel computing system. We distinguish between three aspects of ‘efficiency’: processor efficiency (degree to which the solving algorithm is able to exploit the processor's computational power), parallel efficiency (ratio between computation and communication times) and numerical efficiency (convergence behaviour). With the new FEM software package Feast we pursue the aim to develop a solver mechanism which at the same time gains high efficiencies in all three aspects, while trying to minimise the mentioned dependencies. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

C,N-chelated hexaorganodistannanes, and triorganotin(IV) hydrides and cyclopentadienides

Triorganotin(IV) hydrides and cyclopentadienides as well as hexaorganodistannanes containing the moiety L^CN (2-(N,N-dimethylaminomethyl)phenyl-) as chelating ligand and phenyl, n-butyl or t-butyl substituents were prepared and characterized by NMR and XRD. The compounds reveal trigonal bipyramidal geometry around the central tin atom except for the distannanes in which the tin atom has tetrahedral configuration. The di-n-butyl distannane cannot be oxidized by oxygen or heavier chalcogens and give no tin radical when irradiated by UV light or treated with the TEMPO - free radical at room temperature. L^CN(t-Bu)₂SnH undergoes reaction in solution toward the corresponding distannane. The hydrostannation reaction of L^CN(n-Bu)₂SnH with ferrocenylacetylene was investigated. The CO₂ activation by L^CN(n-Bu)₂SnH was also examined.