The thermodynamic properties of liquid nitromethane under high-pressure have been determined using molecular dynamic (MD) simulations based on classical empirical potentials and first-principles Car-Parrinello method (CPMD). Classical MD simulations were carried out to study the structural and thermodynamics properties of nitromethane under high pressure, and the theoretical Hugoniot was obtained up to 14.2 GPa. For some thermodynamic functions, such as total energy, particle velocity, the classical MD simulations agree well with experimental results. However, it predicts a higher Hugoniot pressure at given density. The CPMD simulations were performed at several selected densities. The radial pair correlation functions, velocity auto-correlation functions, vibration spectra, and other thermodynamic properties have been obtained and compared with the results of classical MD. The careful analysis of the pair correlation functions reveals that the short-range part of the classical potential may be too stiff. There are substantial differences for pair correlation functions between CPMD and classical simulations, while such difference can be attributed as quantum effects. The vibration spectra of liquid nitromethane were obtained from CPMD simulations at ambient conditions and at high pressure. The pressure-induced shifts of vibrations to high frequency predicted by CPMD are consistent with the experimental observation.

By use of split Hopkinson pressure bars (SHPB) technique, a kind of silicon rubber is investigated for understanding its dynamic constitutive behaviors at high strain rates. Experimental results show that silicon rubber is strain-rate sensitive. It shows viscoelastic characteristics at room temperature and high strain rates. Pulse shaping technique is utilized to ensure the dynamic stress equilibrium in the specimen and to obtain a constant strain rate. Quartz crystal is used to monitor the stress equilibrium and to measure the weak signal in the experiments of silicon rubber.

Criterion for determining free electrons in general SCF average atomic model is revised to describe well the existence of the potential in condensed matter, and, partial wave and Fermi-Dirac statistics are employed for dealing with the resonant electrons and free electrons, individually. The electron pressure is acquired by taking into account the contribution of the resonant states and that of exchange and Coulomb correlations among electrons. The electron pressures for Ni and Cu at zero-temperature are calculated and compared with experiments. Applicability of the model is shown via calculations of pressure for Fe and Pb at definite low temperature and some densities.

The weak ferromagnetic behavior arises from the size effects, which gives rise to the distortion of the T′-R₂CuO₄ structure. In this paper, we study magnetic properties on rare-earth cuprates, R₂CuO₄ (R=Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Tm), synthesized under high oxygen pressure (6 GPa) at elevated-temperature. The magnetic susceptibility measurements show a new weak-magnetic component near a characteristic temperature of 28 K. Appearances of the low temperature weak-magnetism are independent of the rare-earth components and are a common behavior of all oxygen-doped T′-R₂CuO₄ cuprates. We argue that (1) the weak ferromagnetic behavior occurred near 28 K couldn’t be attributed to the size effects, but to the formation of ferromagnetic clusters in CuO₂ planes caused by the oxygen-doping under high pressure; (2) superconductivity and weak ferromagnetism seem to be exclusive in T′-R₂CuO₄ compounds, i.e., the ferromagnetic clusters in CuO₂ planes seems to be incompatible with superconductivity in these system.

Detonation science has been annoyed for a long time with the argument that the entropy has a minimum at the process end of detonation models. Neglecting thermodynamics, Newton mechanics that is invariant for the substitution t→-t may create thermodynamic mistake in describing detonation phenomena. The order assumption in CJ and ZND models, which considers all particles of detonation products march orderly in one direction, implies low entropy and thermodynamic non-equilibrium. Overstating CJ and ZND model, or even treating them as the objective reality of detonation process itself hinders the development of detonation science.

Chemical reaction in CuO-Al pre-fabricated blocks is controlled at different temperatures. Thermal analysis curves were determined and X-ray diffraction was used to carry out phase analysis of samples after their reactions, whereby the reaction temperature for producing heat explosion and reaction products at different temperatures were obtained. The results indicate that as the medium temperature rises, three different regions of reaction in the CuO-Al system can be classified. When the temperature is less than 1 200 K, there is no chemical reaction; when the temperature is in the range 1 200~1 437 K, a partial chemical reaction takes place whose products are Cu₂O, CuAlO₂ and Al₂O₃; when the temperature is over 1 473 K, chemical reaction occurs in the CuO-Al system and the reaction products are Cu and Al₂O₃. It is in this latter region that thermal explosion is occurs readily.

For further research of the regularity of B-C-N material prepared by ball-milling method, the micro-crystal mixture of graphite-hexagonal boron nitride (g-hBN) is heat-treated under the pressure of 4.5~5.8 GPa and the temperature of 800 ℃~1 300 ℃. XRD, XPS and FT-IR analysis of the heat-treated products shows: at 4.5 GPa and 800 ℃, there is partial crystallization of hexagonal boron nitride (hBN) in samples, but the graphite keeps the status of micro-crystallization; and at 1 300 ℃, samples not only have crystallization of hBN but also have ternary compound of B-C-N, which is analogous to graphite structure. We considered that the new compound was approximate to BC₃N when we had compared with correlative information of studies. When the pressure is up to 5.8 GPa and the temperature stays at 1 300 ℃, the changes of result are less.

We have worked out one dimensional double region MHD programs for Z-pinch simulation. One of our calculated results of tungsten load has been discussed in the article. The dynamic phenomenon of double wire pinch is presented. The current distribution between the two liners after collision was given. According to our simulation results, 120 GW of X-ray power and 1.0 kJ of X-ray energy are produced in the pinch.

This paper mainly studies Raman spectroscopy of C—H stretching vibrational mode of methanol at 2 835 cm^-1 from 169.2 up to 713.8 MPa under the temperature of 301 K using cubic zirconium oxide Anvil Cell. The result shows that methanol is stable at the experimental pressure, and the Raman shift of methanol at 2 835 cm^-1 shows a linear dependence with pressure. The correlation between pressure and frequency shift of the 2 835 cm^-1 Raman line of methanol is described by p=-3.508 9·[(Δν_p)_{2 835}]² + 135.17 (Δν_p)_{2 835}+54.397, where 0.1<p (MPa) ≤ 713.8. So methanol can be used as a reliable pressure gauge in high hydrostatic experiments.

This paper has discussed the reliability of the Raman spectra of water as a pressure gauge for the hydrothermal diamond anvil cell (HDAC) at pressures of 39~1 150 MPa and a temperature of 26 ℃. The results show a linear relation between pressure and the frequency of the fitted peak: p (MPa)=32.9 (ν_p)_{3 244}+200.7 (3 215 cm^-1<ν_{3 244}<3 244 cm^-1).