[en] This article seeks to assess the role that HVEM has, can, and will display in understanding the fundamental aspects of radiation damage processes. The point to be made is that HVEM provides an excellent scientific method of investigating the primary displacement process, and, especially, secondary defect formation. However, although the electron damage process is much simpler than neutron or ion damage, HVEM damage observations still must be evaluated with extreme caution

[en] This paper reports on several non-radiation-hardened high density static RAMs (SRAMs) that were tested for susceptibility to single event upset (SEU) and latchup. Test results indicate that at present only a few such device types are suitable for use in space applications. Several additional factors such as susceptibility to multiple-bit upsets and to radiation induced permanent damage need to be taken into consideration before these device types can be recommended. One non-hardened SRAM device type has recently been used on a low-Earth orbit satellite, enabling the upset rate measured in space to be compared to that predicted from ground-based testing

[en] It is more and more frequent to introduce electronic equipments in environments where are different nuclear radiations (photons, X, γ, electrons, heavy charged particles and so on). The nuclear interaction phenomena in the materials are not all perturbing, but they all give up energy to components by complex interactions while they modify their performances or by destroying them. The interactions radiation-matter include: the radiations and the electronic active components, the effects induced by the photons, the interactions with electrons, the heavy or loaded particles, the neutronic irradiations. We shall use to characterize these energy layings a few notions as dose, rate dose, activity. Without claiming to make a total list of measurements confronted with the different radiation we shall speak of some topics and bring some numeric data on the perturbing environments. We shall tackle the main defects of interactions radiation-matter. At last we shall show that there must have a previous analysis of the nuclear environment to warrant the reliability. We shall able to think to the question complexity-cost and show that hardness must be considered as for all other perturbing parameters (temperature, humidity). 20 refs., 15 figs., 2 tab

[en] It is shown theoretically and experimentally that the transformation of modes by an astigmatic π/2 converter is invariant with respect to the input-beam displacement and tilt. The possibility is considered of using this property for manipulating microobjects and simultaneous generation of Laguerre-Gaussian modes of different orders with the help of the same astigmatic π/2 converter. (laser modes and beams)

[en] The irradiation with energetic particles causes changes in the properties of materials. The understanding of microscopic processes by which the evolution of macroscopic effects is initiated, is very important for effective overcoming of the problems, related to the macroscopic radiation effects. After describing the basic ideas and models of the radiation damage theory, the emphasis is given to recent experimental and computer simulation results. These results indicate the occurrence of local melting during the displacement spike. The importance of radiation damage in other materials and other fields is also described. (author)

[en] A model and a method are proposed to explain the origin and main specific features of the dynamic patterns of different types, which were previously observed on the free surface of solids under load in experiments. It is shown that the pattern is formed due to the dynamic instability of the flat surface of the solid under load. This instability develops at the relaxation mechanism caused by the dynamic atomic displacements due to a change in the interatomic interaction during the electron-density redistribution.

[en] A metric indicating the relative level of specific radiation damage for individual atoms, that can be calculated from refined and deposited protein structure models, is presented. Radiation damage impedes macromolecular diffraction experiments. Alongside the well known effects of global radiation damage, site-specific radiation damage affects data quality and the veracity of biological conclusions on protein mechanism and function. Site-specific radiation damage follows a relatively predetermined pattern, in that different structural motifs are affected at different dose regimes: in metal-free proteins, disulfide bonds tend to break first followed by the decarboxylation of aspartic and glutamic acids. Even within these damage motifs the decay does not progress uniformly at equal rates. Within the same protein, radiation-induced electron density decay of a particular chemical group is faster than for the same group elsewhere in the protein: an effect known as preferential specific damage. Here, B_D_a_m_a_g_e, a new atomic metric, is defined and validated to recognize protein regions susceptible to specific damage and to quantify the damage at these sites. By applying B_D_a_m_a_g_e to a large set of known protein structures in a statistical survey, correlations between the rates of damage and various physicochemical parameters were identified. Results indicate that specific radiation damage is independent of secondary protein structure. Different disulfide bond groups (spiral, hook, and staple) show dissimilar radiation damage susceptibility. There is a consistent positive correlation between specific damage and solvent accessibility

No abstract available

[en] A simple rule of thumb based on resolution is not adequate to identify the best treatment of atomic displacements in macromolecular structural models. The choice to use isotropic B factors, anisotropic B factors, TLS models or some combination of the three should be validated through statistical analysis of the model refinement. In choosing and refining any crystallographic structural model, there is tension between the desire to extract the most detailed information possible and the necessity to describe no more than what is justified by the observed data. A more complex model is not necessarily a better model. Thus, it is important to validate the choice of parameters as well as validating their refined values. One recurring task is to choose the best model for describing the displacement of each atom about its mean position. At atomic resolution one has the option of devoting six model parameters (a ‘thermal ellipsoid’) to describe the displacement of each atom. At medium resolution one typically devotes at most one model parameter per atom to describe the same thing (a ‘B factor’). At very low resolution one cannot justify the use of even one parameter per atom. Furthermore, this aspect of the structure may be described better by an explicit model of bulk displacements, the most common of which is the translation/libration/screw (TLS) formalism, rather than by assigning some number of parameters to each atom individually. One can sidestep this choice between atomic displacement parameters and TLS descriptions by including both treatments in the same model, but this is not always statistically justifiable. The choice of which treatment is best for a particular structure refinement at a particular resolution can be guided by general considerations of the ratio of model parameters to the number of observations and by specific statistics such as the Hamilton R-factor ratio test

[en] Ideal structures of several 2/1 approximants of icosahedral quasicrystals with the sp. gr. Pm-bar 3 and Pa-bar 3 have been constructed. It is shown that most atoms have dodecadhedral local coordination. The structural features of the crystals studied have been analyzed. It is found that displacements of atoms from ideal positions in real crystals tend to increase with an increase in the distance to the center of the approximant projection on the perpendicular space. Large displacements are generally related to the presence of very close neighbors in the ideal structure of the approximant. The importance of the investigation of approximants as a source of information about the structure of polyatomic nanoclusters is indicated