Computational studies on 3,5,7,10,12,14,15,16-octanitro-3,5,7,10,12,14,15,16-octaaza-pentacyclo[7.5.1.12,8.04,13.06,11]hexadecane as potential high-energy-density compound

The B3LYP/6-31G(d) method of density functional theory was used to study molecular geometry, electronic structure, infrared spectrum, and thermodynamic properties. Detonation properties were evaluated using Kamlet–Jacobs equations based on the calculated density and heat of formation. Thermal stability of 3,5,7,10,12,14,15,16-octanitro-3,5,7,10,12,14,15,16-octaaza-pentacyclo[7.5.1.1^2,8.0^4,13.0^6,11]hexadecane (cage-HMX) was investigated by calculating the bond dissociation energy at unrestricted B3LYP/6-31G(d) level. The calculated results show that the first step of pyrolysis is the rupture of the N–NO₂ bond. The crystal structure obtained by molecular mechanics belongs to P2₁ space group, with lattice parameters a = 8.866 Å, b = 11.527 Å, c = 13.011 Å, Z = 4, and ρ = 2.219 g cm^?3. Both the detonation velocity of 9.79 km s^?1 and the detonation pressure of 45.45 GPa are better than those of CL-20. According to the quantitative standard of energetics and stability as a high-energy-density compound, cage-HMX essentially satisfies this requirement. These results provide basic information for molecular design of novel HEDCs.     

Cooling-induced increase of methane cluster size investigated under a Coulomb explosion scheme

In this letter, we discuss the increase in the average cluster size by lowering the stagnation temperature of the methane （CH4） gas. The Coulomb explosion experiments are conducted to estimate the cluster size and the size distribution. The average CH4 cluster sizes Nay of 6 230 and 6 580 are acquired with the source conditions of 30 bars at 240 K and 60 bars at 296 K, respectively. Empirical estimation suggests a five-fold increase in the average size of the CH4 clusters at 240 K compared with that at room temperature under a backing pressure of 30 bars. A strong nonlinear Hagena parameter relation （Г^＊∝ T0^-3.3） for the CH4 clusters is revealed. The results may be favorable for the production of large-sized clusters by using gases at low temperature and high back pressures.     

Manipulation of atom-to-molecule conversion in a magnetic lattice

Atom-to-molecule conversion by the technique of optical Feshbach resonance in a magnetic lattice is studied in the mean-field approximation. For the case of a shallow lattice, we give the dependence of the atomto-molecule conversion efficiency on tunnelling strength and atomic interaction by taking a double-well as an example. We find that one can obtain a high atom-to-molecule conversion by tuning the tunnelling and interaction strengths of the system. For the case of a deep lattice, we show that the existence of the lattice can improve the atom-to-molecule conversion for certain initial states.     

单行安置的算法

对一j= LSI/VLSI具有积木块的单元，rt卞L给出单f7安置的算法一般来说，给出矩形单元的相对位置后，须从Zw个状态中选出最优解.我们证明在单行安置时可归结为N个状态的问题，得到一种很有效的算法.此算i?;曾用Fortran语言编程并在IBM-PC机上通行，结果令人满意.     

Pattern discrimination and firing behavior of cold receptor model aided with noise

A method for characterizing and identifying firing patterns of neural spike trains is presented. Three characteristic variables defined at sequential moments, including two formal derivatives and the integration of the counting process, are introduced to reflect the temporal patterns of a spike train. This paper also examines how noise interacts with encoding mechanisms of neuronal stimulus in a cold receptor. From ISI series and bifurcation diagrams it is shown that there are considerable differences in interval distributions and impulse patterns caused by purely deterministic simulations and noisy simulations. The ISI-distance can be used as an effective and powerful way to measure the noise effects on spike trains quantitatively. It is found that spike trains observed in cold receptors can be more strongly affected by noise for low temperatures than for high temperatures in some aspects; meanwhile, spike train has greater variability with the noise intensity increasing.