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Using first-principles calculations, we predict mechanical and thermodynamic properties of both Mg17Al12and Mg2Sn precipitates in Mg–Al–Sn alloys. The elastic properties including the polycrystalline bulk modulus, shear modulus, Young’s modulus, Lame’s coefficients and Poisson’s ratio of both Mg17Al12and Mg2Sn phases are determined with the Voigt–Reuss–Hill approximation. Our results of equilibrium lattice constants agree closely with previous experimental and other theoretical results. The ductility and brittleness of the two phases are characterized with the estimation from Cauchy pressure and the value ofB/G. Mechanical anisotropy is characterized by the anisotropic factors and direction-dependent Young’s modulus. The higher Debye temperature of Mg17Al12phase means that it has a higher thermal conductivity and strength of chemical bonding relative to Mg2Sn. The anisotropic sound velocities also indicate the elastic anisotropies of both phase structures. Additionally, density of states and Mulliken population analysis are performed to reveal the bonding nature of both phases. The calculations associated with phonon properties indicate the dynamical stability of both phase structures. The temperature dependences of thermodynamic properties of the two phases are predicted via the quasi-harmonic approximation. [ABSTRACT FROM PUBLISHER]

Objective: To investigate the influence of high frequency stimulation of the subthalamic nucleus on the levels of amino acids neurotransmitters in striatum of hemi-parkinsonian monkeys., Methods: Two rhesus monkeys were successfully prepared for the subsequent microdialysis sessions. Collecting the dialysate before turning on the pulse generator, and collecting at 1 week, 1, 8 and 12 months after high frequency stimulation of the subthalamic nucleus. The level of Glu, GABA and Tau were determined by high performance liquid chromatography and fluorometric detection (HPLC-FD)., Results: After high frequency stimulation (HFS), PD symptoms of monkeys significantly improved. The levels of Glu in putamen and caudate nucleus of electrodes side at 1 week, 1, 8 and 12 months were increased significantly. The levels of GABA in putamen and caudate nucleus of electrodes side at 1 week, 1 month increased significantly compared with before turning on the pulse generator while decreased at 8, 12 months. The level of Tau in putamen and caudate nucleus increased significantly., Conclusion: Long-term STN HFS can increase the level of glutamate and taurine, while decrease the level of GABA in putamen and caudate nucleus of electrodes side. It improves symptoms of hemi-parkinsonian rhesus monkey significantly.