Performance of acrylate-poly(ethylene oxide) polymer electrolytes in lithium batteries

Results for the performance of lithium/Mn0₂ batteries containing solid polymer electrolytes based on poly(ethylene oxide) blends with some acrylic derivatives are presented. The ionic conductivities of the electrolytes are promising for battery application. It was found, however, that interfacial phenomena impair the battery efficiency. Impedance spectroscopy shows resistive limitations at the anode interface of the batteries, caused either by formation of an electrically distinguishable resistive layer or by chemical interaction between the polymer and lithium, influencing, most probably, the kinetics of the lithium oxidation reaction.     

Application of piece‐wise linear weight functions for 2D 8‐node quadrilateral element in contact problems

The present study is a continuation of our previous work with the aim to reduce problems caused by standard higher order elements in contact problems. The difficulties can be attributed to the inherent property of the Galerkin method which gives uneven distributions of nodal forces resulting in oscillating contact pressures. The proposed remedy is use of piece‐wise linear weight functions. The methods to establish stiffness and/or mass matrix for 8‐node quadrilateral element in 2D are presented, i.e. the condensing and direct procedures. The energy and nodal displacement error norms are also checked to establish the convergence ratio. Interpretation of calculated contact pressures is discussed. Two new 2D 8‐node quadrilateral elements, QUAD8C and QUAD8D, are derived and tested in many examples, which show their good performance in contact problems. Copyright © 2004 John Wiley & Sons, Ltd.     

Synthesis and biological studies on analogs of cyclolinopeptide A with a shortened peptide chain

Continuing our work on the immunosuppressive activity of cyclolinopeptide A (CLA), a cyclic nonapeptide of the sequence: c-(-Leu-Ile-Ile-Leu-Val-Pro-Pro-Phe-Phe), we synthesized a series of 6 linear analogs of CLA, successively shortened at the N-terminus of the peptide chain. Immunosuppressive activity of acetates as well as trifluoroacetates of these peptides was investigated using PFC (humoral immunity) and DTH (cellular immunity) tests. It was found that the immunosuppressive potency of the peptides examined diminishes with shortening of the peptide chain. Octapeptide I with the sequence Ile-Ile-Leu-Val-Pro-Pro-Phe-Phe was found to be the most active of the whole series. The immunosuppressive activity increased again for a tripeptide fragment of CLA of the sequence Pro-Phe-Phe. The immunosuppressive activity of octapeptide probably depends on the suppression of IL-1, IL-6 and TNF production by the cells involved in immune and inflammatory response.     

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Book reviews

     

Simulation of Temperature Distribution in Stored Wheat without Aeration

A neural-deterministic simulation model applied for calculating distributions of temperatures and moisture content in a bed of wheat stored in a steel silo without aeration is presented in the article. The model consists of differential equations of heat and moisture transfer, initial and boundary conditions, and three artificial neural networks used during simulated ambient air conditions. Experiments and computer simulations were carried out in order to determine temperature fields in wheat grain stored in a steel silo for two months. The computer simulations were carried using MATLAB and FEMLAB software. The difference between measured and simulated temperature in grain near the silo wall at a height of 2.5 m from the bottom was less than 3.0°C. On the basis of the analysis performed it was concluded that the temperature distributions obtained with the model were consistent with the measured results obtained for grain stored in a steel silo without aeration.     

Microprocessor debugging techniques and their application in debugger design

Every microprocessor-based system needs powerful debugging tools. Debugging power strongly depends on a mechanism of control exchange between the debugger and an application program. Several implementation methods of such a mechanism are briefly described and compared in this paper. It is shown that conditional breakpoints facilitate a semantics-oriented approach to program debugging. Some debugging techniques derived from elementary control-exchange mechanisms are proposed. Most of the techniques discussed are implemented in the MD-86 debugger designed for the Intel 8086 microprocessor. The debugger itself is also briefly described.     

The influence of biomass co-combustion on boiler fouling and efficiency

The paper presents an attempt to evaluate the influence of biomass co-combustion on the fouling of boiler convection surfaces. In order to show the influence of co-firing biomass with bituminous coal on boiler efficiency, the calculations of pulverized fuel (PF) OP 140 steam generator have been carried out. Typical Upper Silesian coal with medium fouling inclination has been chosen as a basic fuel. Three kinds of biomass have been taken into consideration: straw, wood and dried sewage sludge. The results confirm that the properties of additional fuels cause deterioration of the boiler efficiency as well as the changes in boilers operational parameters (amount of water injected in attemperators, ash stream, hot air temperature). The biomass during cofiring in fact replaces the coal, but always the additional fuel consumption is higher than that of the substituted coal. Therefore, the actual decrease of coal consumption is smaller than the thermal fraction of the biomass.