Interaction potential between two 16O nuclei derived from the Skyrme interaction

The energy functional for the Skyrme density-dependent force is used to calculate the interaction potential between two ¹⁶O nuclei. A two-centre harmonic oscillator potential is employed to construct the density and kinetic energy density of the ground state of the combined system and of the separated nuclei. The antisymmetrization effects are investigated. The relative motion of the nuclei is taken approximately into account and the energy dependence of the potential derived from the Skyrme force is presented.     

Conversion of methanol over 10-ring zeolites with differing volumes at channel intersections: comparison of TNU-9, IM-5, ZSM-11 and ZSM-5

Four 3D 10-ring zeolites, IM-5, TNU-9, ZSM-11 and ZSM-5, with Si/Al = 14-24 and crystal sizes below 2 microns, were tested as catalysts for the methanol to hydrocarbons reaction (MTH) at atmospheric pressure, 350 °C and WHSV = 9 h(-1). All catalysts gave initially full methanol conversion, and showed strikingly similar effluent product selectivities. However, their life-time duration differed significantly, and decreased in the order: ZSM-11 > ZSM-5 ? TNU-9 > IM-5. A main difference between the two groups of stability behaviour was the size of cavities formed by channel intersections; larger cavities in TNU-9 and IM-5 leading to polyaromatics formation and a more rapid deactivation compared to ZSM-5 and ZSM-11. Effluent yield-conversion plots suggested that polymethylated benzene intermediates were more important in IM-5 and TNU-9 than in ZSM-5 and ZSM-11, where alkene methylation and cracking reactions seemed to dominate product formation. However, this difference had only minor influence on effluent selectivity.     

Classical trajectory calculations with time-dependent forces in heavy-ion collisions

The applicability of a phenomenological time-dependent nucleus-nucleus potential to deep inelastic collisions is studied. We present its general shape and make a particular choice of the diabatic and adiabatic parts. From trajectory calculations we find that the angle-energy correlation is well described when a time-dependent friction force is used. We also compare our results to some TDHF calculations.     

PRODUCTION OF PIGMENT NANOPARTICLES USING A WET STIRRED MILL WITH POLYMERIC MEDIA

Pigment nanoparticles with a size range of 10-100 nm were produced from large agglonmerates via a stirred media mill operating in the wet-batch mode and using polymeric media,The effects of several operating variables such as the surfactant concentration,polystyrene media loading.and media size on the pigment size distribution of the product were studied.The process dynamics was also investigated.Dynamic light scattering and electron microscopy were used as the characerization techniques.The polymeric grinding media are found to be effective for the production of pigment nanoparticles.The experimental results suggest the existence of an optimum media size and surfactant concentration,A population balance model of the process reveals a transition from first-order breakage kinetice for rela-large agglomerates split in a first-order kinetics,with a delay period,for the smaller particles.The model implies that large agglomerates split in a first-order fashion whereas the breakage of individual naoparticles may depend on induced fatigue of the particles.     

超声速化学反应流动中燃料预喷研究述评

研制基于超声速燃烧的高效吸气式推进装置(运行Mach数在3.5以上)需要寻求改善混合效率的有效机制, 这对于采用常规碳氢燃料(特别是可以增加密度的液体燃料)的装置尤为重要. 延长混合时间的一种途径是在飞行器燃料室的上游喷入部分燃料. 壁面喷射一直是超声速气动力学最具挑战性的课题, 这里包括使比冲损失最小、改善燃料-空气的混合、减少入口段/燃烧室的相互作用以及增进火焰稳定性等. 综述了超声速入口段或燃烧室的隔离器中液体燃料(个别情况下为气体燃料)喷射的研究进展. 在这些研究中, 燃料都是从后掠型细支架尾迹中的壁面处喷射出来的, 动压比很低($q_{\rm {jet}}/q_{\rm {air}}$=0.6$\sim$1.5). 它们涉及入口段和燃烧室的隔离器中单个支架/喷射器的几何结构及其组合方式、各种各样的喷射条件、不同的引射剂, 并且评估了这些因素对于燃料羽流喷散、比冲损失以及混合效率的影响. 述评引用了46篇参考文献.     

Editorial for Focus Issue on Enabling Science and Technology for High-Speed Optical Communications

<正>Fiber optics underpins the communications infrastructure for the information society today. Cables consisting of hair-like fibers speed data around the globe in the form of rapid pulses of light. Modern telecom     

Watching the Methanol-to-Olefin Process with Time- and Space-Resolved High-Energy Operando X-ray Diffraction

The movement of reactants in a large methanol-to-olefin reactor bed was visualized by fast scanning synchrotron X-ray diffraction. Changes in the structure of the catalyst showed the formation of reaction intermediates and coke, which can be tracked along the reactor bed. The observations lead to a new model for the progress of the reaction and explain the role of methanol in coke formation.     

The modified electronic mass approach for the adiabatic corrections in H2

A theory of the modified (distance dependent) electronic mass effect for two-electron diatomic molecules is presented. The modified electronic mass correction is compared with the diagonal Born-Oppenheimer correction to the potential energy curves of H₂, suggesting that the adiabatic correction is almost exactly accounted for by this effect.