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In situ TEM straining experiments have been performed on a Ti3Al single crystal, along the c-axis, in order to study the slip of 2c+a dislocations in pyramidal planes. The results show that slip takes place in π1 planes, in contrast with what has been observed after compression tests (slip in π2 planes), and that rows of loops are nucleated in the slip plane. The mechanisms which may control slip in the π1 planes are briefly discussed.
In situ experiments have been conducted in NiAl single crystals in the soft orientation, at room temperature, in order to investigate the glide process of  dislocations. The results show that dislocations have a kinked shape in agreement with what is expected from anisotropie elasticity. Intensive cross-slip is observed, leading to slip in non-crystallographic planes and dipole formation. The ductility of the alloy is then discussed.
Groundwater circulation is in the long term probably the most important mechanism for the transport of radionuclides from deep underground repositories to the biosphere. The fate of leached long-lived nuclides, such as the actinides, is of particular interest to repository safety analysis. Both experimental and theoretical studies should lead to a comprehensive description of their behaviour in the geosphere.
TEM observations of dislocations and faults in an as-grown Al-Pd-Mn single crystal show that dislocation movements have occurred by pure climb in mirror planes. A comparison with creep properties of h.c.p. metals along their c-axis indicates that pure climb is a realistic deformation mode when glide is inhibited at high temperature.
The glide properties of <001> dislocations have been studied by in situ straining experiments at and below room temperature, with the aim of studying slip, cross-slip, Peierls friction forces, and pinning at small obstacles. Most results are in a good agreement with atomistic calculations. It is concluded that unpinning from small extrinsic obstacles is probably the rate controlling mechanism in this temperature range and in the soft orientation.
TEM observations have been performed in AlPdMn single-grain quasicrystal deformed at low temperature. They show that dislocation motion has occurred by climb associated with vacancy diffusion. At room temperature, deformation also occurs by crack followed by re-healing.
Large Angle Convergent Beam Electron Diffraction (LACBED) experiments on
dislocations located in the mirror planes of icosahedral AlPdMn single grains
show that – as previously inferred from standard image contrast
technique – the direction of the Burgers vector is perpendicular to
the mirror plane of movement, thus confirming the fact that climb
should be an important process for the plasticity mechanisms in icosahedral
A group of 480 patients, aged 19–78 with an HRSD score of at least 17 and who met DSM–III criteria for major depressive disorder were studied. Patients were given placebo for a one-week single-blind run-in period, after which sertraline was administered for eight weeks. This was followed by 44 weeks in which patients received sertraline or placebo on a double-blind, randomised basis. Patients were assessed periodically using the 17-item HRSD and the Clinical Global Impression scales. During the entire double-blind period 24 (13.0%) sertraline patients relapsed compared with 48 (45.7%) placebo patients (P<0.001). The protective effect of sertraline was maintained throughout the 44 weeks. The study provides evidence that sertraline prevents relapse of the index episode of depression as well as recurrence of further episodes and has few side-effects.
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