Serendipity Virtual Elements for General Elliptic Equations in Three Dimensions

The authors study the use of the virtual element method (VEM for short) of order k for general second order elliptic problems with variable coefficients in three space dimensions. Moreover, they investigate numerically also the serendipity version of the VEM and the associated computational gain in terms of degrees of freedom.     

The reaction mechanism in the system132Xe+56Fe at 5.73 MeV/u: Evidence for a new type of strongly damped collisions

We present data for the¹³²Xe+⁵⁶Fe-system at 5.73 MeV/u laboratory energy. Due to inverted kinematics, where Xe is the projectile, we were able to measure energy spectra as well as angular distributions for reaction products with 20≦Z≦60 with unitZ-resolution; i.e. target- and projectile-like fragments have been investigated. The reaction shows a well focussed quasielastic component, where charge transfer from the light to the heavy collision partner dominates. This apparent tendency towards more asymmetric fragmentation is explained by a potential energy surface which favours such charge transfer in order to minimize the asymmetry energy of the liquid drop. The strongly damped component which constitutes the major part of the reaction cross section exhibits characteristics of a fusion-fission reaction with typical fission fragment kinetic energies and 1/sinΘ _c.m. angular distributions. The maximum cross section is found for the symmetric fragmentation, no clear indication is observed for a diffusion process leading to target- and projectile-like fragments. Our data are difficult to reconcile either with the standard diffusion models or with an equilibrated compound nucleus fission picture. We tentatively conclude that an essential part of the fully damped cross section originates from partial waves for which the compound nucleus has no fission barrier.     

MAGNETIC FIELD EFFECT OF THE EUROPIUM a8S7/2-z6P7/2 LINES

The magnetic field effect of a⁸S_7/2-z⁶P_7/2 lines of ¹⁵¹Eu and ¹⁵³Eu in magnetic fields up to 66.7 mT has been studied by using laser atomic beam spectroscopy. The Zeeman level structures of the europium a⁸S_7/2 and z⁶P_7/2 states in magnetic fields were discussed. The location and intensity of the measured Zeeman transition lines were found in good agreement with the theoretical results.     

一种新型MAO改性的高活性铬基气相聚乙烯催化剂

制备了一种新型的CrO3／SiO2／MAO(／EtOAlEt2)乙烯聚合催化剂，在微机控制的自动评价装置上进行了乙烯气相聚合评价试验，研究了催化剂制备中有机铝化合物对催化剂的改性作用．结果表明，MAO作为还原剂可以明显提高催化剂的聚合活性，显著影响乙烯聚合反应动力学，得到的聚乙烯树脂融体流动速率较低．同时采用MAO和EtOAlEt2作为还原剂制备催化剂时，二者具有显著的协同效应，催化剂聚合活性高，临氢效应敏感高，树脂的融体流动速率高．     

强激光装置中玻璃疵病在线检测的光学系统设计

介绍了一种用于玻璃疵病在线检测的近摄工作距成像光学系统,其光组结构形式采用了光阑后置的准远心结构形式,主要光学参量为f′=14 mm;在物像距为250 mm约束条件下,物方视场达到90 mm(对角线);F/number=3.56;光谱适应范围为400～800 nm,对应的空间分辨率为100 lp/mm时,调制传递函数大于0.29.     

杯[8]芳烃键合硅胶固定相的制备、表征及色谱性能

杯芳烃通过疏水Π-Π、氢键和静电等作用能与中性分子及离子形成包合物,在离子选择性电极、催化、分离和酶模拟等领域受到关注.已报道的杯芳烃键合固定相的制备方法^[1～3]都是先合成含杯芳烃硅烷化试剂,然后通过硅胶硅烷化反应制备键合固定相.其制备路线反应过程长,各种有机中间体纯化操作复杂.前文[4]曾以氯丙基键合硅胶为中间体,通过固相连续反应制备了氮杂冠醚键合硅胶固定相.本文采用固相连续反应制备了一种新型的对-叔丁基杯^[8]芳烃键合固定相,通过元素分析、红外光谱等手段获得键合相分子结构信息,以多环芳烃和二取代苯位置异构体为溶质,对固定相的色谱性能及保留机理进行了研究.