Recent advances in lead—acid cell research and development

The lead—acid battery is, and will be for the foreseeable future, the most widely used secondary energy storage system. It will maintain this predominant rôle because of its highly developed technology, its low cost as compared with other secondary systems, and its high reliability.During the last decade it has been demonstrated that the lead—acid system is able to provide an attractive energy source of sufficient energy and power per unit weight and volume for its successful application to electric vehicle propulsion. Worldwide basic research has contributed to the improvement of both active material utilization and cycle life. This will be shown by a number of typical examples, such as the relations between active material properties and capacity at high rates of discharge, the effect of acid stratification, and others. Simultaneously, the expenditure on the maintenance of lead—acid batteries has been minimized by the development of peripheric equipment such as recombination devices and means for central-automatic water refill. It will be shown that there is still a considerable potential for further improvement which might further strengthen the unique position of the lead—acid system in the market by comparison with competitive systems.     

Retention of prose materials as a function of postacquisition testing.

One-wk prose retention was examined as a function of 4 activities immediately following reading. 24 Ss served in each of 7 conditions. Completion questions as an immediate activity with knowledge of results produced significantly better delayed retention than did questions without knowledge of results or presentation of statements equivalent in information to the questions with knowledge of results. These 3 conditions yielded performance significantly superior to the nonactivity control. Knowledge of results did not increase retention for correctly answered immediate questions, and it significantly increased delayed performance for immediate questions incorrectly answered. The immediate activity facilitation findings were attributed to 2 processes, practice at retrieval of stored information and addition of answers to items not recallable immediately after reading. No delayed retention difference occurred between passage information and equivalent randomly presented statements. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of short-fibre reinforcement on the fracture behaviour of a bulk liquid crystal polymer

The microstructure and some mechanical properties of a liquid crystal polymer (LCP) and its short-fibre composites have been investigated. Injection moulded plates of the latter materials exhibit a layered structure well-known for many short-fibre reinforced polymer systems. A pronounced layered structure is also found in the neat LCP matrix, superimposed by a certain degree of molecular orientation. The special, microstructural character of the matrix polymer results in a high anisotropy of the mechanical properties of all materials investigated. In particular, this is found for the tensile strength, the fracture toughness and the fatigue crack propagation. The composites show nearly no improvement or even a reduction in their performance, compared to the matrix material, as far as these properties are concerned. This can, in part, be correlated to microscopic failure mechanisms detected by scanning electron microscopy of the fractured surfaces, revealing that the fibre-matrix bond strength is relatively poor.     

High Temperature Corrosion on high temperature materials – Metallographic,scanning electron microscopic and microanalytical tests

High temperature corrosion – oxidative damage of metallic materials from hot gas and other fluid and solid components – shortens the life of gas turbines. By comparing the results of laboratory tests under constant conditions with the results of the operation of gas turbines the facts of failure should be clarified. Metallographie examinations, but especially SEM, Microprobe and AES help to clear the facts of failures in the microscopic zones. These tests will help when selecting materials and their protective coatings with the purpose of higher rentability of the plant.     

Mechanism of Ca-ATPase inhibition by melittin in skeletal sarcoplasmic reticulum

We have previously shown that the basic, amphipathic peptide melittin inhibits the Ca-ATPase of the sarcoplasmic reticulum membrane by inducing large-scale aggregation of the enzyme via electrostatic cross-linking. To better understand the physical mechanism by which melittin-induced Ca-ATPase aggregation inhibits the enzyme, we have performed time-resolved phosphorescence anisotropy (TPA) and steady-state fluorescence experiments in combination with enzyme kinetic assays, utilizing (1) native and charge-modified melittin in order to characterize the peptide charge dependence of the melittin-SR interaction, and (2) various calcium levels in order to define the effect of melittin on the enzyme's E1 and E2 conformational equilibrium. TPA results showed that decreasing melittin's positive charge dramatically decreases the ability of the peptide to aggregate the enzyme, which correlates with a reduced potency of the modified peptide to inhibit enzymatic activity. Steady-state fluorescence of fluorescein isothiocyanate-labeled Ca-ATPase showed that melittin reduces Ca-ATPase affinity for calcium by shifting the enzyme's E1-E2 conformational equilibrium toward E2, but increasing calcium progressively reverses this shift. Kinetic experiments showed that melittin does not prevent ATP-dependent enzyme phosphorylation, but it completely inhibits Pi-dependent EP formation and substantially slows Pi release during steady-state cycling. We conclude that melittin-induced aggregation of the Ca-ATPase depends on the electrostatic interaction of the peptide with cytoplasmic Ca(2+)-dependent sites on the enzyme, and that enforced Ca-ATPase protein-protein interactions inhibit the conformational transitions that facilitate phosphoenzyme hydrolysis.     

Block iterative finite element preprocessed scheme for simulation of large non-linear problems

The ‘Block Iterative Finite Element Preprocessed Scheme’ (BIFEPS) for finite element simulation combines two independent steps. In the ‘finite element preporcessing step’, spatial information about the finite element mesh is analysed and all integrals arising from the application of the Galerkin method are evaluated and stored on a permanent sequential storage unit (such as tape or disk). In the ‘block iterative step’, the preprocessed information is retrieved from permanent storage and the matrix equation is assembled and solved in an efficient manner according to a generalization of the block successive over-relaxation iterative method. Significant advantages over common finite element simulation techniques are achieved in terms of both computer core requirements and execution time. Numerical experiments show that the advantages of BIFEPS are greatest for large, non-linear simulation problems.