[en] Based on the first-principles of density functional theory and the ultra-soft pseudo-potential method of plane wave, it is a mature method for calculating the optical properties of materials. We use MS software to simulate the rutile phase TiO₂ under different doping conditions. The content includes the energy band structure, electronic density and optical properties of TiO₂ under five different conditions : undoped and single-doped Mo, single-doped N, co-doped Mo-N, and co-doped N-Mo-W. Theoretical calculations show that : it is concluded that single doping can change the forbidden band width of TiO₂, but it is not effective compared to co-doped Mo-N and W-N and N-Mo-W. Among them, when W is doped, a new impurity level appears in the bottom of the conduction band, and the conduction band decreases more than the valence band decreases. The forbidden band width is narrowed, so that the effect is obvious in the case of single doping. In the co-doping, the valence band of N-Mo-W exhibits a clear impurity level, and it is easier to transit the valence electron to the conduction band due the fact that of the energy level near the Fermi-level, and the energy level at this time The higher density is also an important reason for the obvious doping effect. (authors)

[en] The band structures and state densities of armchair silicon nanotubes with chiral index m = n = K (integer K is 3 ∼ 15) are studied by using the first-principles method of density functional theory in this paper. The results show that (3, 3) armchair silicon nanotube is the indirect band-gap structure, and the rest are the direct band-gap structure. With the increase of the chiral index, the diameter of the silicon nanotubes increases, the band-gap width of the silicon nanotubes decreases gradually, the conduction band moves down gradually, and the peak intensity of the total density diagram increases. (3, 3) armchair silicon nanotube has the widest band-gap. Armchair silicon nanotube (13, 13) has the smallest band-gap width, indicating that its electrical conductivity is better than those of armchair silicon nanotubes with other chiral indexes. Meanwhile, the conduction and valence bands of (4, 4) armchair silico nanotube overlap, indicating that it is the metallic nanotube. The state density diagram shows that the top of the valence band of (9, 9) armchair silicon nanotube is mainly composed of Si-3p electron states, and the bottom of the conduction band is composed of Si-3p and Si-3s state electrons. (authors)

[en] The band structure and density of states of zigzag single-walled silicon nanotubes (SWSiNTs) are calculated by the local density approximation method in the first principle. The calculation results show that when n = 6 ∼ 9, the band gap is 0 and the group of SWSiNTs is metallic, when n = 10 ∼ 21, the band gap appears in the band diagram and the group SWSiNTs is semiconducting, when n = 13 ∼ 21, the band gap of the SWSiNTs of this group decreases with three groups of chiral indices. Both the absorption spectrum and the reflection spectrum produce peaks near some similar frequency values. (authors)

[en] In this paper, the first-principles plane wave super-soft pseudopotential method based on density functional theory is used to calculate rutile TiO₂. Which includes the pure TiO₂ and single-doped Al, single-doped N and co-doped Al-N four different conditions of the band structure and density of TiO₂ and the density of light absorption coefficient of the study. The calculated results show that the ability of light absorption is improved by the addition of Al and N, but the effect is not good. When the Al-N is co-doped, the lattice constant of TiO₂ is changed and a new impurity level appears. Since the impurity energy level exists in the band gap of TiO₂, the energy required for electron transition to conduction band is reduced, Thereby increasing its light absorption capacity, the effect relative to the single doping is more obvious improvement. (authors)

[en] The electronic structure, state density, elastic constants and photoelectric properties of Mg₂Ge are calculated by using the first principle of density functional theory. The results show that Mg₂Ge is an indirect bandgap semiconductor, and the bandgap is 0.2136 eV. The valence band and conduction band are mainly composed of Ge 4s and 4p electrons, and Mg 3s, 3p and Ge 4p electrons, respectively. The static dielectric constant is 25.294, and the refractive index is 4.5043. The maximum peak value of the absorption coefficient is 396, 560.9 cm^-1. The brittleness of Mg₂Ge is explained by elastic constants. The calculated Mg₂Ge photoelectric properties and its energy band structure are analyzed, which provides theoretical basis and experimental guidance for Mg₂Ge in the field of photoelectric application. (authors)

[en] The electronic structures and optical properties of Mg₂Ge at different Al doped concentrations were calculated by using the first principle of density functional theory. Four doping models of Mg_2-xAl_xGe (x = 0, 0.125, 0.25, 0.5) were established. The calculation results show that the Al-doped Mg₂Ge Fermi level enters the conduction band and exhibits n-type conductivity characteristics. After doping, the conduction structure near the Fermi energy level of Mg₂Ge was changed to be composed of Al 3p electrons, and Ge 4s electrons and Mg 3s, 3p electrons. The static permittivity and refractive index increase. The absorption spectrum is redshifted and the maximum absorption coefficient decreases slightly. The peak value of photoconductivity is obtained when x = 0.125. The blue shift occurs in the energy loss function, and it is most obvious when x = 0.125. (authors)

[en] Under water environment, nanometer RDX was produced by wet grinding. With the help of Zetasizer Nano, field emission scanning electron microscope, Custer type hammer instrument, its particle size distribution, morphology appearance, the sense and other properties were characterized and then the safety of the process of crushing was analyzed. The experimental results show that the sensitivity of nanoscale RDX prepared by wet method is significantly reduced and the safety is improved. Due to the low cost of this method, it is possible to reutilize large-scale recycled RDX, which solves the difficulties of storing and transporting the RDX and expands its scope of use. (paper)

[en] Objective: To compare the efficacy of ¹³¹I alone and ¹³¹I combined with prednisone tablets in the treatment of patients with Graves' disease (GD) and to predict the clinic value of the combined therapy. Methods: 66 patients with GD received ¹³¹I therapy were divided into two groups: 5 mg prednisone tablets once a day starting 2 weeks after ¹³¹I therapy and continued for 6 weeks (group A ), ¹³¹I therapy alone (group B). The methimazole and bisoprolol tablets to alleviate symptom were given to patients in the both group when necessary were received. The cure rate, cure time and methimazole and bisoprolol tablets consumption of two groups were compared. Results: There was no significant difference on cure rate between group A and group B. However, the recovery time for thyroid function, methimazole and bisoprolol tablets consumption in group A were significantly less than that in group B (P < 0.05). Conclusion: ¹³¹I combined with prednisone tablets for the treatment of GD show potential efficacy, it may rapidly improve symptoms and reduce early complications. (authors)

[en] Preparation of thin films by thermal evaporation is a commonly used method that is simple to operate and may be easily scaled for industrialization. So we prepared Mg₂Ge semiconductor thin films by resistive thermal evaporation and vacuum heat treatment. First, Mg films with thicknesses of ∼460 nm were deposited on Ge(111) substrates and then annealed at 400 °C under low vacuum (10⁻¹–10⁻² Pa) in an annealing furnace. Various annealing times 3, 4, 5, 6, and 7 h were used. The structure and morphology of each film were characterized by x-ray diffraction, scanning electron microscopy, and Raman spectroscopy. The effect of annealing time on the quality of Mg₂Ge thin film growth was studied. We demonstrate that resistive thermal evaporation allows successful preparation of single-phase Mg₂Ge semiconductor thin films. We observed that with increasing annealing time, the quality of Mg₂Ge thin film first improves and then deteriorates, and for an annealing time of 5 h, this is optimized. Our results provide a reference for the preparation of Mg₂Ge semiconductor thin films. (paper)

[en] By using first-principle calculation method based on density functional theory, the electronic structures and magnetic properties of 3C-SiC doped with Co at different concentrations, doped with Al and co-doped with Co and Al are studied. The results show that the average contribution of single Co atom to the total magnetic moment is reduced with the increasing Co doping concentration. By analyzing the spin state density of electron in 3C-SiC, the magnetic moment is primarily contributed by Co-3d electrons and C-2p electrons near the Co atoms. Both the average magnetic moment per atom and the total magnetic moment are zero in Al-doped 3C-SiC. In other words, the single Al-dopant is nonmagnetic. And the total magnetic moment of Co-Al co-doped 3C-SiC is more than 0.09 μB to the 3C-SiC doped with a comparable amount of Co. The reason is that Co atoms located in Co-Al co-doped 3C-SiC show more average contribution to magnetic moment due to the orbital hybridization between Co-3d and Al-3p electrons. (authors)