In order to investigate the effects of combined treatment of ultra high pressure (UHP) and enzyme inhibitors on the activities of peroxidase (POD) and pectin methyl esterase (PME) in litchi pulp, two kinds of enzyme inhibitor prescriptions were designed including group A (citric acid 5 g/L+L-ascorbic acid 2.5 g/L+calcium chloride 5 g/L) and group B (citric acid 10 g/L+L-ascorbic acid 5 g/L+calcium chloride 10 g/L). After being immersed in enzyme inhibitor solutions for 10 min, the pulp of litchi (Litchi chinensis Sonn cv. Huaizhi) was subjected to UHP treatment (100~400 MPa for 30 min at 10 ℃). The activities of POD and PME were detected by spectrophotometry. Results showed that separate treatment of group A or group B could lead to obvious passivation of POD and prominent activation of PME. Combined treatment of UHP and group A could not make the activities of POD and PME decrease. The influence of combined treatment of UHP and group B on POD and PME had relevance to pressure value, the POD activity lowered when the combined treatment of 100~300 MPa and group B was applied, and the PME activity raised obviously when the combined treatment of 200~400 MPa and group B was applied. So, combined treatment of UHP and enzyme inhibitors had certain synergistic effect for POD inactivation, and the synergistic inhibition effect would be more obvious with higher concentration of enzyme inhibitors; but combined treatment of UHP and enzyme inhibitors showed certain rivalry for PME inactivation.

We studied the effect of high pressure process (HPP) on exoproteinase of Bacillus subtilis by using Box-Behnken response surface methodology. Experimental results showed that HPP could inhibit activity of exoproteinase significantly. In the course of treatment, pressure and temperature were key factors to passivate enzyme, and their interaction was notable. A model of exoproteinase passivation was established by design expert software, which determination coefficient was 0.974 7 and adjusted determination coefficient was 0.942 1. Analysis of variance implied that the model was significant. Therefore, the model could be used to analyze and predict. Additionally, the experiment indicated that exoproteinase activity correlated with lethal rate significantly (R=0.933 0). The exoproteinase could be regarded as an index to evaluate effect of HPP on microorganism.

Aimed at idiographic structure of DAVIS gun, for accurately calculating acceleration of projectile in bore, this article emulationally calculated the launch of a DAVIS gun through classical interior ballistics, acquired the interior ballistic parameters-time curves and educed the acceleration-time curve of projectile according to bore pressure-acceleration relation. The calculated results accorded with the experimental data.

Planar shock compression effects on damage and cracking in Zr₄₁Ti₁₄Cu_12.5Ni₁₀Be_22.5 bulk amorphous alloy are studied using a two-stage light gas gun. The experimental result indicates that the cracking angel θ of bulk amorphous alloy under planar shock compression is smaller than that of traditional compression experiment, it is decided by the highest strain velocity under shock compression conditions in bulk amorphous alloy; part of bulk amorphous alloy surface also is melt by the effects of highest strain velocity and the energy of partial adiabatic shear bands; the crystallization happens in bulk amorphous alloy by the effects of temperature and pressure.

By analyzing both of dynamic behavior and existing constitutive models of concrete, a new constitutive model has been built to simulate dynamic response of concrete. The main factors such as pressure, the third invariant of stress tensor, strain hardening and softening, stain rate and tensile damage have been taken into account in the constitutive model. After calibrating all parameters of the model, simulation of a perforation problem on concrete target has been carried out with the Lagrangian finite element code LTZ-2D. The computed results of residual velocity are well consistent with the test data, and a reasonable figure of fractured concrete target is obtained. Results demonstrated that the built constitutive model could well describe the main characters of concrete under impact loading.

Based on the experimental results of the elastic precursor attenuation along with propagation distance, with rate-dependent constitutive relation including dislocation parameters, and according to the thermally activated dislocation motion model proposed by Gilman, the lower bounds of the initial mobile dislocation densities N₀ and the drag stresses τ₀ have been obtained for LY12-aluminum, MB₂-magnesium and lead respectively on the order of 10⁶ cm^-2 and 0.1 GPa, but for stainless steel, N₀ and τ₀ are on the order of 10⁸ cm^-2 and 1.5 GPa. With the elastic precusor decay curve, the upper limits of the effective viscosity coefficient μ have been given also for LY12-aluminum and magnesium on the order of 10³ Pa·s, and for 2^#-iron and stainless steel on the order of 10⁴ Pa·s.

The second-order manifold method (MM) is used to simulate the dynamic Hopkinson spalling process of rock under shock loading through introducing a criterion of crack initiation and crack growth. The attenuation of stress waves and the spalling process caused by a reflected tensile stress wave are reproduced. The simulation results are compared with theoretical analysis. The thickness of the formed scab and its velocity obtained from the simulation are in good agreement with the theoretical values. MM has proven to be an effective method in simulating the dynamic failure process of materials under shock loading and exhibits some advantages to conventional numerical methods in the study of dynamic failure and related issues.

The incident shock wave focusing and reflection on the two parabolic reflectors were studied by means of high speed photograph technique and numerical simulation method. The experimental shadow photographs and computational density contours were obtained, and the good agreements between the experimental and computational results were presented. The properties of the gasdynamic focus, formed by shock wave focusing, were analyzed. The results show that for both reflectors studied the gasdynamic focus is formed by the collision of two triple points at the axis, and that this focus is located in the vicinity of the corresponding geometrical focus. The shock-shock structures after shock wave focusing are different for the two reflectors. For the shallow reflector, the bow shock waves form on the surface of reflector before the reflection of incident shock wave; it takes long time to complete the focusing once incident shock wave reflects from reflector; the bow shock waves do not intersect each other during the shock wave focusing and reflection. For the deep reflector, it takes short time to complete the focusing, the bow shock waves have intersected during the shock wave focusing and reflector, and this process leads to the more complex shock-shock structure.

The rules regarding the propagation of irreversible phase boundaries along a finite rod are investigated with a phase transition constitutive model based on the simple mixture theory. The results show that the boundary and loading/unloading conditions strongly affect the propagation pattern of the phase boundaries, and the final distribution shapes of the volume fraction for the product phase along the rod are different under various end boundaries. The new phenomena observed in the recent Taylor bar tests are explained in this paper, and the possibility for producing symmetric distributed functionally graded materials with impact method is proposed.

Experimental results showed that the Me₃C (Me means Fe, Ni) pattern carbides produced by the action of catalyst and graphite are main carbon source to form diamond structure under high temperature and high pressure (HPHT). In this paper, based on the empirical electron theory of solids and molecules (EET), the valence electron structure (VES) and interface structure factors of diamond and various carbides are calculated, and the boundary condition of Thomas-Fermi-Dirac-Cheng (TFDC) is applied to the carbide/diamond interfaces. It is found that the electron density of crystal face in Me₃C formed by C—C bonds is continuous with that of diamond at the first order of approximation, but the continuous intensity of different carbide is different. The VES of plane composed of C atoms in (FeNi)₃C and Co₃C are more similar to that of diamond, so the energy needed to transform their C—C bonds to diamond structure is lower. The catalyst action and catalysis mechanism are explained on the basis of VES concerning the carbides and diamond. This method may be a new way to investigate the mechanism concerning diamond formation.