High resolution imaging and elemental analysis of PAGE electrophoretograms by scanning proton microprobe

Metal content of metalloproteins can be detected and even quantified by the PIXE–PAGE method. In this technique the proteins are separated by thin layer electrophoresis (by polyacrylamide gel electrophoresis (PAGE) in most cases) and the properly dried gel sections are analyzed by PIXE using “band-shaped” proton milli-beam. This PIXE–PAGE method was adapted for our scanning proton microprobe. The microPIXE–PAGE version provides two-dimensional elemental mapping of the protein bands. In addition, the fast continuous scanning reduces the risk of the thermal deterioration of the sample and the X-ray contribution from dust-impurities can be filtered out in the data evaluation process.     

Delineation of Subsea Freshwater Extension by Marine Geoelectromagnetic Soundings (SE Mediterranean Sea)

This study presents a novel application of marine geoelectromagnetic technique, in an attempt to delineate freshwater extension of the coastal sub-aquifers beneath the SE Mediterranean Sea, along central Israel. The novel marine Ex-Bz time domain electromagnetic (TDEM) geophysical method was applied, demonstrating high sensitivity to the presence of sub-seafloor electrically resistive structures up to several kilometers offshore (shallow marine environment). The study included 19 marine measurements located offshore between Ashdod in the south to Tel-Aviv in the north, where a previous onshore study detected fresh groundwater below seawater intrusion at the coast line. The offshore measurements were conducted to distances of up to 3 km from the shoreline. It was found that the lower sub-aquifer contains fresh groundwater (resistivity >10 Ω-m) to a distance of 2.8 km offshore along the 30 km strip, and is probably constrained by lateral geo-facial changes.     

Finite element analysis of a polymer composite subjected to a sliding steel asperity Part I Normal fibre orientation

FE micro-models have been developed in order to determine contact, stress and strain conditions produced by a steel asperity sliding on the surface of a normally oriented fibre-reinforced polymer composite. A displacement coupling technique was introduced to model a micro-environment as part of a macro-environment and to get more realistic simulation results about the failure conditions in the composite structure, in comparison to the so far widely applied anisotropic analytical or numerical macro-models. On the basis of the results, conclusions may be drawn for the possible wear mechanisms of the fibre-reinforced polymer composite. Stress results in the vicinity of the fibers in the contact area show high shear loading of the matrix leading to the formation of stretched-out matrix wear debris. In addition, high repeated compression-tension stresses at the fibre/matrix interface near the surface can lead to fibre debonding phenomena. Considering the fibre ends in the contact region, high compression stresses at their rear edges can produce fibre cracking features. To study the wear mechanisms experimentally, a single asperity scratch test was also performed showing shear failure events of the polymer matrix, fibre/matrix debonding and fibre cracking effects, as expected from the modelling studies.     

Occurrence and type of traumatic experiences among young Bosnian refugees in Denmark

Prior research has shown that young refugees may be especially traumatised. The study includes 123 young Bosnian refugees, living at two Bosnian boarding-schools in Denmark who were given a revised version of the Harvard Trauma Questionnaire (HTQ). The subjects themselves have on average experienced seven traumatic events, and have either witnessed or had a family member experience an additional six events. Three-quarters have been shot at, have lost their homes and private possession and have been exposed to violence in the form of harassment or humiliation. Two-thirds have lost friends. Three-fifths have lived with uncertainty as to whether friends and family were alive or dead. More than half have seen dead and wounded people, have had their lives threatened and have thought that they would die. More than a third have lost close family members, have been wounded and have had their homes destroyed. Just under a third have been exposed to physical violence or have witnessed somebody being killed. A quarter have starved and been ill without being able to receive treatment. About a fifth have experienced captivity, torture and forced labour. 6% have been raped or exposed to other forms of sexual abuse. It is concluded that the young Bosnians examined are a multitraumatised group. Use of the HTQ increased the number of traumatic events quite considerably compared to the case notes.     

Point defects as sources of micropolar effects in elastic continua

It is shown in this paper that point defects in an elastic continuum can cause micropolar effects. Using micropolar elasticity transversal microrotation and displacement wave fields are derived which arise from the interaction of point defects with a longitudinal wave. It is shown that the microrotation wave can exist even in a classical elastic continuim.     

The influence of Mg content on the formation and reversion of Guinier-Preston zones in Al-4.5 at % Zn-x Mg alloys

The influence of Mg concentrations on the dissolution of Guinier-Preston (GP) zones formed at room temperature (RT) and on the formation of more stable phases has been investigated during continuous heating of Al-4.5 at % Zn-xMg alloys. The Mg content was varied from 0.05 to 3 at %. After different aging periods at RT, calorimetric investigations were carried out at heating rates of 40 and 80° C min⁻¹. In the case of alloys with a lower Mg content (x ⩽ 0.5 at %) only the dissolution of GP zones could be observed during the heating, whereas in the case of alloys with a higher Mg content the formation of theη′-phase started before the total dissolution of GP zones and at higher temperatures the formation of theη-phase also took place. These phases were identified by transmission electron microscopy. The heat-of-solution of GP zones shows saturation as a function of RT aging time. The time needed for the saturation increased monotonously with increasing Mg content. The reversion of zones was followed byin situ X-ray small angle scattering measurements. The change of the total scattered intensity was measured during continuous heating at a rate of 40° C min⁻¹. These investigations have confirmed the results of the calorimetric measurements which indicate that the total dissolution of zones takes place only in the case of the alloys with a Mg content lower than 0.5 at %. In the case of alloys with a Zn concentration of 4.5 at % studied here, 1 at % Mg is sufficient to initiate the formation of more stable phases during the reversion of zones. On leave from Hanoi University, Vietnam.     

On the decomposition behaviour of Al-4.5 at% Zn-2 to 3 at% Mg alloys during continuous heating

The decomposition processes taking place in the Al-4.5 at % Zn-2 to 3 at % Mg alloys were studied during continuous heating by means of electrical resistivity, XSAS and DSC measurements and by TEM investigations. It was found that the room temperature pre-ageing has no significant influence on the processes taking place above 230° C. Several temperature ranges were determined in which the decomposition of the solid solution and/or the transformation of the different particles of the second phases take place by different mechanisms.