配备于自旋回波仪的计算机系统

本文介绍配备在自旋回波仪中的计算机系统,由TP-801计算机、外围设备、接口电路和一套应用软件组成。该系统可以产生自旋回波实验所需要的多种脉冲序列,包括90°-90°、90°-180°、180°-90°、Carr-Purcell序列等。同时,计算机采集回波信号或FID,并进行数据处理,其结果可以直接由计算机或示波器、绘图仪显示,也可以存入磁带。仪器可以快速准确地测量弛豫时间T₁、T₂,也适用于核磁共振自旋回波方面的教学。在本文结束部分给出了一些样品的测量结果。本文介绍的计算机系统可以和普通的CW-NMR谱仪结合,使之增加自旋回波测量功能。     

The thermodynamic equilibrium of the formation process of High-Tc superconducting phase YBa2Cu3O7−x

Analysing the equilibrium state of the formation reaction of the high-T_c superconducting phase 1:2:3 (YBa₂Cu₃O_7−x) on the base of the pressure-temperature-oxygen content (P-T−x) correlation research and using the Van't-Hoff equation, the Gibbs free energy (ΔG_m) of the reaction has been calculated for the first time. It is seen that the absolute value of ΔG_m is not large and of the order of 2.5 kcal · mole⁻¹. This leads to an instability of the 1:2:3 phase. Also, from the calculated values of ΔG_m relative stability regions of the 1:2:3 phase are determined for different values of x. Combinatively analysing the relation lg P = A−B/T (where A – the x-dependent constant, and value of B was determined to be equal to 10518 atm. K) and the value of ΔG_m, we come to the conclusion that the synthesis of YBa₂Cu₃O_{7 − x} when x → 0 must be carried out under high oxygen pressure and low temperature for a lasting time, because the reaction rate is limited by slow diffusion in the solid phase.     

Nucleoside-assisted self-assembly of oligo(p-phenylenevinylene)s at liquid/solid interface: chirality and nanostructures

The formation of DNA nucleoside-assisted π-conjugated nanostructures was studied by means of scanning tunneling microscopy (STM) and force field simulations. Upon adsorption of the achiral oligo(p-phenylenevinylene) (OPV) derivative at the liquid/solid interface, racemic conglomerates with mirror related rosettes are formed. Addition of the DNA nucleosides D- and L-thymidine, which act as "chiral handles", has a major effect on the supramolecular structure and the expression of chirality of the achiral OPV molecules. The influence of these "chiral handles" on the expression of chirality is probed at two levels: monolayer symmetry and monolayer orientation with respect to the substrate. This was further explored by tuning the molar ratio of the building blocks. Molecular modeling simulations give an atomistic insight into the monolayer construction, as well as the energetics governing the assembly. Thymidine is able to direct the chirality and the pattern of OPV molecules on the surface, creating chiral lamellae of π-conjugated dimers.     

Molecular patterning at a liquid/solid interface: the foldamer approach

Molecular patterning has received a lot of attention in the past decade; however, the functionalization of these surface-confined 2D patterns on the nanoscale level remains a challenge. Assembling 2D patterns from oligomeric foldamers turns out to be an interesting approach to accomplishing the controlled positioning of functional elements. We designed a family of peptidomimetic foldamers bearing a 2D turn element folding at the liquid/solid interface. The turning element was developed while studying derivatives with one turning unit. Furthermore, folding was found to be induced by the confinement of the surface. This achievement paves the way for the design of foldamers with multiple turns, providing a higher versatility in the functionalization of nanopatterns.     

自蔓延高温合成法在陶瓷领域的应用

自蔓延高温合成法（ＳＨＳ）及相关技术在材料科学的应用引起了人们的广泛重视，本文总结了ＳＨＳ在陶瓷领域的应用。     

Synthesis and Steric Structure of β-Lactam Derivatives of 2,4-Diaryl-2,3-dihydro-1,5-benzothiazepines

2,4-Diaryl-2,3-dihydro-l,5-benicthiazepines1posscsspotentbiologicalactivities1-3.CycloadditionreactionsatC=Ndoublebondmaypeaesttheconstructionofnewcyclicsystemsthatmayhaveneweffectsonstereochemistryandbiologicalactivitiesof1,5benzothiazepines.Followingourstudyonaseriesofreactionsofcompounds1,westudiedthecycloadditionreactionof1withchloroacetylchloride.Thetitlecompoundsarepresented.Especially,theirconfiguration(therelativestericpositionoftheCIandphenylgroups)andconformationwereestablishedbyX-…     

丙酮和丙醛分子的多光子电离碎片化机理

用多光子电离一飞行时间质谱法在激光波长为532nm处获得了丙醛和丙酮分子的MPIF－TOF质谱．实验测得了各碎片离子占总离子信号的百分比对激光强度的依赖关系．并用这些实验结果对两酮和丙醛分子的MPIF机理作了分析．还对H＋、C＋和CH＋等小质量碎片离子的可能形成过程作了讨论．     

细分市场

以往凭借巧克力系列、闪耀（Shine）系列等时尚手机打天下的韩国厂商LG,在今年可谓势头强劲,除了推出代号为“迷”（Secret）的目前市面上最薄500万像素滑盖手机KF755外,还发布了数量不少的其他新品来获得更多的市场份额。其中包括巧克力系列第三代产品LG Chocolate 3．KM380以及我们今天要给大家介绍的KF300。     

三星也玩手写三星L258手机

直板＋手写的设计我们往往在国产MTK平台手机上看到,而三星近日推出的一款新品L258,也采用了这样的设计,在三星丰富的手机产品线中显得比较另类。那么三星的直板手机和平时已经快让我们审美疲劳的MTK平台的直板手写机型有什么区别呢？请随我们一起来仔细品味三星这款手写新品吧。     

便携也疯狂 11款超便携笔记本电脑横向评测

人们常说需求决定市场,但有时市场也会引导人们的消费需求。回想三年前,如果消费者想购买12英寸的笔记本电脑,没有上万元的购机预算款,那也只有想想而已。12英寸以下的笔记本电脑更是只有观望的份,但今年情况却大不一样,年初已经有几家厂商把7寸、8寸、10寸的超便携笔记本相继在市场上推出,年底则几乎所有的笔记本厂商都加入到超便携笔记本电脑这个市场之中了,