Density functional theory study of the {\alpha} --> {\omega} martensitic transformation in titanium induced by hydrostatic pressure

The martensitic {\alpha} --> {\omega} transition was investigated in Ti under hydrostatic pressure. The calculations were carried out using the density functional theory (DFT) framework in combination with the Birch-Murnaghan equation of state. The calculated ground-state properties of {\alpha} and {\omega} phases of Ti, their bulk moduli and pressure derivatives are in agreement with the previous experimental data. The lattice constants of {\alpha} and {\omega}-phase at 0 K were modeled as a function of pressure from 0 to 74 GPa and 0 to 119 GPa, respectively. It is shown that the lattice constants vary in a nonlinear manner upon compression. The calculated lattice parameters were used to describe the {\alpha} --> {\omega} transition and show that the phase transition can be obtained at 0 GPa and 0 K.Comment: 6 pages, 5 figure

Electronic structure, charge transfer, and intrinsic luminescence of gadolinium oxide nanoparticles: Experiment and theory

The cubic (c) and monoclinic (m) polymorphs of Gd2O3 were studied using the combined analysis of several materials science techniques - X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. Density functional theory (DFT) based calculations for the samples under study were performed as well. The cubic phase of gadolinium oxide (c-Gd2O3) synthesized using a precipitation method exhibits spheroidal-like nanoclusters with well-defined edges assembled from primary nanoparticles with an average size of 50 nm, whereas the monoclinic phase of gadolinium oxide (m-Gd2O3) deposited using explosive pyrolysis has a denser structure compared with natural gadolinia. This phase also has a structure composed of three-dimensional complex agglomerates without clear-edged boundaries that are ~21 nm in size plus a cubic phase admixture of only 2 at. % composed of primary edge-boundary nanoparticles ~15 nm in size. These atomic features appear in the electronic structure as different defects ([Gd...O-OH] and [Gd...O-O]) and have dissimilar contributions to the charge-transfer processes among the appropriate electronic states with ambiguous contributions in the Gd 5p - O 2s core-like levels in the valence band structures. The origin of [Gd...O-OH] defects found by XPS was well-supported by PL analysis. The electronic and atomic structures of the synthesized gadolinias calculated using DFT were compared and discussed on the basis of the well-known joint OKT-van der Laan model, and good agreement was established.Comment: 27 pages, 10 figures, accepted in Appl. Surf. Sc

Fear of Crime and its Related Social Factors Among the Elderly Citizens of Shiraz

Abstract The aim of this research is to investigate the situation of the fear of crime and its related social factors among the elderly in the city of Shiraz. This study is done within the framework of a quantitative methodology employing a survey method. The demographic population of the study are the elderly citizens of shiraz, 330 of them were selected through multilevel random sampling. The research tool was a questionnaire, indexes of which were validated through content and factor validity and its reliability was examined by the Cronbach alpha coefficient and test re-test reliability. In the theoretical part of fear of crime, different perspectives of social integration, social capital, demography theories, interpersonal communication and victimology were examined, and the conclusions of this research were determined using such frameworks. According to the findings of this research, the fear of crime among the elderly citizens of Shiraz was estimated to be average in the measurement scale of the research. The analysis of the content variables showed that respondents were significantly different in terms of the fear of crime based on different variables of age, gender, marriage, and level of education.  The fear of crime increased with an increase in age. A higher level of education reduced the fear of crime and so on. The inferential findings of this research study showed that social capital, as one of the independent variables of the research, affected fear of crime either directly or indirectly. However, its indirect effect was more (on skill) on dependence variable (fear of crime). Skill, as another independent variable of the research, has a direct and significant effect on fear of crime. The analysis of the research conclusions shows that fear of crime as a social phenomenon is prevalent among the elderly across the world both theoretically and experimentally which is affected by different social, mental, and environmental conditions and in order to reduce it among the elderly population, we need to get help from the inherent and individual capacities available in society including non-governmental organizations, media and more, in addition to understanding different aspects of it. Keywords: Fear of Crime, Elderly Citizens, Skill, Social Capital, Shira