Electronic aspects of formation and properties of local structures around Mn in Cd1−xMnxTe1−ySey

Local electronic and structural features around Mn in Cd1−xMnxTe0.97Se0.03 (x = 0.02; 0.05; 0.1; y = 0.03) were studied by means of X-ray Absorption Fine Structure (XAFS) techniques. Manganese ions with an average valence 2+, are found to be well incorporated into the host CdTe lattice, with clear preference for Te atoms as the first neighbors. However, Mn and Te are found to form two essentially different types of bonds, one short, strong and directional (cubic MnTe-alike bond), and three much longer, predominantly ionic in nature (hexagonal MnTe-alike bonds), thereby distorting the tetrahedral coordination around Mn. The origin of peculiar Mn–Te bonds distribution and details of their nature and strength are further elaborated by employing the first principle electronic structure calculations. That way a thorough insight in impact of the Mn–Te bond length variation on the electronic structure of the compound is obtained. The relations established between the local structures and electronic properties offer a reliable procedure for detailed analysis of the structural and electronic consequences of the 3d-transition metals (TM) incorporation in II–VI semiconductor host. Clear distinction between various influences makes the procedure easily adoptable also to the studies of TM impurities in other semiconductors

Influence of Cr and Ni doping on PbTe local structural properties

Structural aspects of Cr and Ni incorporation into the PbTe lattice are studied by means of Extended X-ray Absorption Fine Structure (EXAFS). EXAFS measurements enabled to get exact information on Pb and Te local structural features and their thermal evolution. The obtained results also revealed that by distorting their local environment, impurity atoms (Cr, Ni) add to high inherent disorder already present in the host PbTe. Larger anharmonicity of the Pb–Te bond and larger atomic thermal parameters observed in PbTe(Cr, Ni) could be of interest for thermoelectronics applications since they are both expected to reduce the thermal conductivity

Survey of Electronic and Local Structural Properties of Cd1−x_{1−x}Cox_xSe1−y_{1−y}Te(S)y_y by XAFS

As an extension of our previous studies of multi-component semiconductors doped with magnetic impurities, this paper gives a comprehensive insight into electronic and local structure of crystalline semiconductors Cd$_{0.98}$Co$_{0.02}$Se, Cd$_{0.98}$Co$_{0.02}$Se$_{0.9}$S$_{0.1}$, and Cd$_{0.98}$Co$_{0.02}$Se$_{0.9}$Te$_{0.1}$. Detailed characterization of Co and Se local environment and overall influence of Co and S(Te) (co)doping on the host crystal structure has been obtained by X-ray absorption fine structure (XAFS) technique and electronic structure calculations. Important structural information on bond lengths and disorder parameters were extracted from the extended region of the absorption spectra, while the relationships between electronic and local structures were determined from the characteristic features appearing in the near-edge spectral region. The influence of various structural defects on local electronic properties, charge transfer and atomic interactions has been studied by theoretical modeling of XAFS spectra and calculations of local density of electronic states. The obtained findings offer possible means for improvement and extension of the practical application of CdSe-based materials by adjusting the details of their electronic structure

The associations between socioeconomic status and lifestyle factors in European adolescents: a population based study

The main purpose of the present study was to determine the associations between socioeconomic status (SES) and lifestyle factors. In this cross-sectional study, participants were 3,072 adolescents from two European countries of Lithuania and Serbia. The dependent variable was SES, while independent variables were gender, adherence to a Mediterranean diet, body-mass index, self-rated health, psychological distress, moderateto-vigorous physical activity and sedentary behaviour. The associations between dependent and independent variables were analysed by using logistic regression analysis. In univariate model, middle/high SES was associated with higher adherence to a Mediterranean diet (ptrend = 0.003), good self-rated health (OR 1.51; 95 % CI 1.12 to 2.05) and meeting recommendations of moderate-to-vigorous physical activity (OR 2.09; 95 % CI 1.45 to 3.00), yet inversely associated with psychological distress (OR 0.81; 95 % CI 0.66 to 0.99) and sedentary behaviour (OR 0.80; 95 % CI 0.68 to 0.94). No associations were found between SES and body-mass index and gender. In multivariate model, the same associations occurred between middle/high SES and lifestyle factors. In conclusion, special strategies and policies, based on more affordable nutrition and participation in moderate-tovigorous physical activity, should be implemented within the system

Comprehensive studies of structural, electronic and magnetic properties of Zn0.95Co0.05O\mathrm{Zn_{0.95}Co_{0.05}O} nanopowders

X-ray absorption (XANES, EXAFS, XMCD) and photoelectron (XPS) spectroscopic techniques were employed to study local structural, electronic and magnetic properties of Zn$_{0.95}$Co$_{0.05}$O nanopowders. The substitutional Co$^{2+}$ ions are incorporated in ZnO lattice at regular Zn sites and the sample is characterized by high structural order. There was no sign of ferromagnetic ordering of Co magnetic moments and the sample is in paramagnetic state at all temperatures down to 5 K. The possible connection of the structural defects with the absence of ferromagnetism is discussed on the basis of theoretical calculations of the O K-edge absorption spectra

Solvent effects on structural changes in self-healing epoxy composites

Nowadays, there is a very high importance of composite research and variety of their applications in the modern world. In that sense, we researched hollow glass capillaries filled with dissolved Grubbs catalyst (GC) and dicyclopentadiene (DCPD) were incorporated into a fiber-reinforced epoxy with the aim of improving the flow of healing agents to the crack site. The morphological investigation of the crack site was performed using field emission scanning electron microscopy (FESEM), showing the difference between the samples depending on the used solvent. The software analysis of sample photographs has been performed by calculating the fractured/healed surface area of the samples, revealing that approximately 20% of the volume was affected by the impact. Fourier transform infrared spectroscopy (FTIR) revealed that poly (dicyclopentadiene) (PDCPD) formed at the healed interface. However, the FTIR investigation of catalyst stability in different solvents showed structural changes in GC and partial deactivation. The mechanical tests of the samples showed that a recovery of 60% after 24 h at room temperature could be achieved through the use of a solvent and very low concentration of GC. The performed research results are a good base to develop the model for predicting the processes and morphology, with the goal to design the final mechanical and in the future, thermal, properties in advance. This opens a new direction for future research in the field of composite healing