Analog filter pair design on the basis of a gyrator–capacitor prototype circuit

The paper presents an algorithmic approach to a low‐sensitivity design strategy for analog filter pairs based on a gyrator–capacitor prototype circuit. The general structure of the prototype circuit is proposed. It assumed that the generic structure of the prototype circuit can evolve, with the use of additional gyrators, into a circuit with increased redundancy. It is shown that symbolic analysis of the prototype circuit, used to formulate a set of nonlinear algebraic equations, is necessary to achieve a sufficiently high algorithm operation speed. To find a solution to this specific system of nonlinear algebraic equations, different numerical methods are compared. The modified Hooke and Jeeves algorithm is found to be the most effective. The elaborated algorithms and programs are illustrated with the seventh‐order filter pair example. The obtained filter is better than the filter obtained using LC ladder structures with respect to chip area and power consumption, and these improvements are obtained without loss of sensitivity properties. Copyright © 2010 John Wiley & Sons, Ltd.     

Wood adhesives derived from hyperbranched polyglycerol cross-linked with hexamethoxymethyl melamines

Wood adhesive system based on hyperbranched polyglycerol cross-linked with hexamethoxymethyl melamines was described. The obtained results showed that it was possible to develop polyglycerol-based interior-grade adhesive exhibiting dry shear strengths of the joints exceeding that of the solid wood. Gelling times of the studied formulations were comparable to those of the industrial thermosetting systems (60–80 s at 100 °C). It was also found that wet shear strengths depended on functionality and F/Me molar ratio in the cross-linking resin.     

Understanding defect-related issues limiting efficiency of CIGS solar cells

Many electrical characteristics of Cu(In,Ga)Se₂-based solar cells, including current-voltage characteristics, are affected by specific properties of negative-U defects in the absorber. We present these characteristics and discuss them in the framework of a V_Se-V_Cu defect model proposed by Lany and Zunger. We show how these defects influence photocarrier transport and the dominant recombination mechanism, and hence also the photovoltaic parameters of the cells. Numerical simulations validating our approach will also be presented.     

The discrepancies in energy balance in furnace testing,a bug or a feature?

The paper aims to explain the differences found in the heat release rate measurements in a large sample of standard fire tests (EN 1363-1). A total of 379 tests of vertical assemblies was investigated, all performed in furnace SPARK of the ITB Fire Testing Laboratory, in 2015-2018. The assemblies were subdivided into two groups—wall assemblies and fire-rated doors. These assemblies were also compared with the results of the test of a wall built with aerated autoclaved concrete blocks that was considered as the benchmark test. It was observed that walls built with highly insulated sandwich panels require less heat to maintain standard thermal exposure conditions (20%-30% less) than their counterparts built from gypsum plasterboard or aluminium and fire-rated glass. In case of doors, it was observed that combustible samples required significantly less heat than the benchmark case (40%-70% less), which indicates that the combustion of the sample inside of the furnace was an additional, significant source of heat release, that may skew the qualitative assessment of their performance in fire. A more in-depth discussion of the results is provided, with some ideas on the direction of further developments in fire testing.     

Optimal design of a Kirchhoff-Love plate of variable thickness by application of the minimum principle

Structural and Multidisciplinary Optimization - An approximate thickness optimization of a rectangular Kirchhoff-Love plate with variable stiffness under uniform load is performed in this paper....     

Influence of platelet-activating factor,lyso-platelet-activating factor and edelfosine on Langmuir monolayers imitating plasma membranes of cell lines differing in susceptibility to anti-cancer treatment: the effect of plasmalogen level

Three structurally related but differing in biological activities single-chained ether phospholipids (PAF (platelet-activating factor) and lyso-PAF) and an anti-cancer drug (edelfosine (ED)) were investigated in Langmuir monolayers imitating natural membranes. The aim of the undertaken experiments was to study the influence of these lipids on monolayers mimicking plasma membranes of cell lines differing in susceptibility to the anti-cancer activity of ED, i.e. promyelocytic leukaemia cells (HL-60) and promyeloblastic leukaemia cells (K-562). As these cells differ essentially in the cholesterol/phospholipid ratio and plasmalogen concentration in the membrane, we have carried out systematic investigations in artificial systems of various compositions. The results for model leukaemia cell membrane were compared with data acquired for systems imitating normal leucocytes. Our results show that the level of plasmalogens significantly modulates the influence of the single-chained phospholipids on the investigated systems. The experiments confirmed also that the interactions of ether lipids with a model membrane of HL-60 cells (in biological tests sensitive to ED) have opposite character when compared with K-562, being resistant to ED. Moreover, the values of the parameters characterizing monolayers serving as membrane models (strength of interactions, monolayers fluidity and morphology) proved both sensitivity of these cells to ED and lack of their susceptibility towards PAF. Interestingly, it has been found that lyso-PAF, which is usually described as an inactive precursor of PAF, displays a stronger effect on HL-60 model membranes than ED.