Search

The phonon spectrum of ordered zincblende Si50Ge50 alloy is calculated by ab initio method. The energy band structure at zero pressure and the pressure dependence of phonon dispersion curves are shown up to 20 GPa. The calculation finds a pressure-induced softening of the transverse acoustic phonon mode and the mode frequency reaching zero at about 14 GPa, which indicate breaking of the symmetry and formation of a new phase under high pressure. [ABSTRACT FROM AUTHOR]

Abstract: First-principles and pseudopotential approaches have been used to investigate band structures and pressure dependence of the bandgaps of zincblende Ge50Sn50 ordered alloy up to 9 GPa. It is found that the direct bandgap increases almost linearly with pressure to a maximum value 0.72 eV at 4.7 GPa where direct-to-indirect at L point transition of the bandgap takes place. At 6.8 GPa, an indirect bandgap transition from L to Δ 1 (near X) point takes place. [Copyright &y& Elsevier]

Abstract: First principles and pseudopotential approaches have been used to investigate the electronic properties of α and β polymorphs about compounds Ti3SiC2 and Ti3GeC2. In order to study the variations in properties induced by two different elements in the same phase, the effects of Si substitution to Ge are considered. For both α and β-phase, it is found that the replacement of Ge to Si doesn'' t change much their original electronic properties, and the main differences in total density of states between −9 to −6 eV mainly derive from the changes of s orbit at 2b or 2d Wyckoff positions. [Copyright &y& Elsevier]

Abstract: The goal of this paper is to undertake a detailed first principle calculation of the structural, electronic and optical properties of Sn1− x Sb x O2. The results show that the stability of Sn1− x Sb x O2 in the full range of Sb content points to the probability of a continuous solid solution, where the increasing Sb content leads to volume expansion with different variation trends in the lattice constants. The increase of Sb concentration in the semiconductor–metal–semimetal transition occurs in consonance with the corresponding changes in its structural, electronic and optical properties. Two competing mechanisms play essential roles in this transition, namely; the many body effect and the atom disorder. Our calculations concur with previous X-ray diffraction, sheet resistance, resistivity and optical parameters detections. The studies present a practical way of tailoring the physical behaviors of Sn1− x Sb x O2 through the alloying technique. [Copyright &y& Elsevier]

Objective: Through an interventional study in the metabolic syndrome, evaluate the feasibility of the standard nutritional intervention., Design: Select metabolic syndrome patients from people who received a health check in our hospital and randomly allocate them into four groups. The standard interventional group received both the nutritional intervention and health education; the simple interventional group only received the nutritional intervention; the simple health educational group only received health education; the control group did not receive any intervention measure. Examine the related index of the metabolic syndrome of each group before and half a year after the intervention: waistline, blood pressure, triglyceride, fasting plasma glucose etc. K-W test and Chi-square test, Bonferroni correction was used in our study., Outcomes: The index of the metabolic syndrome was significantly different for each of the four groups before and after intervention (p<0.05). Relative to the control group the total index for the standard nutritional interventional group and for, the simple health education group was significantly different, but there was no difference for the other indices (p>0.05) between the standard nutritional interventional group and simple nutritional interventional group, except that the waistline difference (p<0.005) showed statistical significance., Conclusion: The standard nutritional intervention is an effective strategy for patients with the metabolic syndrome.