左心室壁局部范围MRI三维有限元应变解析

利用磁共振标记技术对左心室壁进行局部三维有限元应变的分析．在…个心动周期内，分别拍摄24张短轴平面图像和长轴平面图像，然后进行合成，求解出健康人左心室壁上各个位置不同时刻的位移和应变，为临床应用和定量准确地评价心功能提供重要的理论依据．     

Improvement of Electrical Properties of the Ge2Sb2Te5 Film by Doping Si for Phase-Change Random Access Memory

Si-doped Ge2Sb2Te5 films have been prepared by dc magnetron co-sputtering with Ge2Sb2Te5 and Si targets. The addition of Si in the Ge2Sb2Te5 film results in the increase of both crystallization temperature and phasetransition temperature from face-centred-cubic （fcc） phase to hexagonal （hex） phase. The resistivity of the Ge2Sb2Te5 film shows a significant increase with the Si doping. When doping 11.8 at.% of Si in the film, the resistivity after 460℃ annealing increases from 1 to 11 mΩ.cm and dynamic resistance increase from 64 to 99Ω compared to the undoped Ge2Sb2Te5 film. This is very helpful to writing current reduction of phase-change random access memory.     

健康人左心室壁位移的MRI解析

用磁共振技术在整个心动周期对健康人左心室壁上的点进行追踪，从而对左心室壁各领域的位移进行有限元解析，为定量、准确地评价心功能提供必要的依据．     

用Gaussian 98程序计算钪和钛原子价层电子组态能量

用Gaussian98程序计算了钪和钛原子的价电子组态能量。计算表明,Hartree-Fock(HF)迭代应采用可靠性较高的QC标准方法,所得的波函数要进行稳定性分析,根据布居分析调整电子的初始占据轨道,以便最终得到所需要的原子组态,在全组态相互作用CASSCF计算中,需要用关键词GUESS=ALTER选择适当的活动组态空间,计算结果说明,随着计算从基态转向激发态,从原子序数小的钪转向原子序数大的钛,需要考虑的因素明显加多,根据HF,QCISD（T）和PM4SDTQ计算得到Sc:3d^254s(^4F)与Sc:3d4s^2(^2D)的能量差分别是96.80,152.92和149.10KJ/mol,与实验值138.75KJ/mol相一致,根据HF,QCISD（T）和CASSCF（4,5）计算得到Ti:3d^34s(^5F)和Ti:3d^24s^2(^3F)的能量差分别为57.85,91.74和82.06KJ/mol,与实验值80.88KJ/mol相一致。     

红收获蚁杜氏腺体细胞壁成分的气相色谱/质谱鉴定

用气相色谱/质谱联用技术对红收获蚁Pogonomyrmex barbatus和Pogonomyrmex maricopa的杜氏腺体(Dufour gland)细胞壁的化学成分进行了鉴定。结果表明：其杜氏腺体的主要成分是烃类化合物。根据红收获蚁Dufour腺体的气相色谱，质谱的谱图，讨论了生物种属的气相色谱/质谱化学分类的可能性。研究表明：同一物种的生物体给出的图谱有一一对应的直观样式，生物组织化学成分的鉴定是生物化学分类的关键，相对峰高或峰面积百分含量不易表征图谱样式。     

水杨亚胺基钯催化聚合丙烯的密度泛函理论研究

Grubbs水杨亚胺基镍/钯催化剂是一类新型含氮、氧配位杂原子的中性单组分 烯烃聚合催化剂。以不带取代基的水杨亚胺钯为模型催化剂，采用密度泛函理论 在B2LYP/LANL2DZ水平上对其催化聚合丙烯的链增长机理进行了研究。与催化剂配 位原子氮的对位进攻相比，丙烯从氧的对位进攻的复合能大、插入能低。当烷基链 在配位原子O的对位时1，2-插入速率低于2，1-插入；当烷基链在配位原子N对位时 ，1，2-插入速率高于2，1-插生产方式。能量量低的插入路径是烷基链在N对位是 的1，2-插入。2，1-插入路径中的γ-氢桥键烷基配合物能异构化得三个β-氢桥键 的烷基配合物，空间位阻最小的最稳定。1，2-插往前只生成一个β-氢桥键烷基配 合物。与氮原子对位的配合物相比，所有在配位原子氧对位的β-氢桥键的烷基配 合物都是更稳定的配合物构型。     

CONFORMATION AND CHAIN PACKING STRUCTURES OF POLY (ρ-PHENYLEN BENZOBISTHIAZOLE) BY MOLECULAR SIMULATION*

The conformation, the chain packing stabilization and the unit cell modeling of poly(p-phenylene benzobisthiazole) have been investigated by using molecular simulation techniquein the present work. A coupling behaviour of σ-bond rotations at either side of the pheny-lene ring or the heterocyclic ring was found surely to exceed a length of the repeat unit ofthe polymer chain. For a single chain model, the stable torsion angle of the repeat resultedat 14°. In the crystalline cell minimization, the dihedral angle along the polymer chaincould even be stabilized in various values. It therefore indicates that the intermolecularinteraction does play a considerable role for this polymer forming the conformation. Ac-cording to cohesive energies calculated for these unit cell models, the torsion angle in themost stable crystalline cell is 0°. When the chains packing together, there exist so manyenergy stable wells along the chain axis 0.35--0.36nm apart from neighbouring chains.Most of the unit cells have quite closed cohesive energies. These factors thus cause thedifficulty of forming an unique perfect crystalline structure of the polymer. The presentstudy suggested a number of reasonable unit cells, and the most stable crystalline structurefor this polymer that is monoclinic, non-primitive unit cell.     

Highly sensitive torsion sensor based on Mach–Zehnder interference in helical seven-core fiber taper

We propose a high-sensitivity bidirectional torsion sensor using a helical seven-core fiber taper embedded in multimode fiber(MHSTM).Sensors with different taper waists and helical pitches are fabricated,and their transmission spectra are obtained and analyzed.The waist and length of the sandwiched seven-core fiber are finally determined to be 68 μm and3 mm,respectively.The experimental results show that the clockwise and counterclockwise torsion sensitivities of the proposed sensor are 2.253 nm...     

2,3-二芳基马来酸酐环合反应机理的计算研究

在B₃LYP/6-311+G(d,p)//HF/3-21G水平上研究了2,3-二芳基马来酸酐环合反应机理.2,3-二芳基马来酸酐环合反应有两条反应途径:(1)反应过程中涉及的各种构型始终保持反式,即中心成环碳原子上的取代基团甲基或氢原子位于分子平面的异侧,这些构型具有C₂对称性;(2)反应过程中涉及的各种构型始终保持顺式,即中心成环碳原子上的取代基团甲基或氢原子位于分子平面的同一侧面,这些构型可具有Cs对称性.二芳基乙烯类化合物环合反应的位垒计算结果与Woodward-Hoffman原理一致,计算结果支持在环合碳原子上引入甲基能改善反应的热不可逆反应性能的实验结果.电荷分析表明,在环合碳原子上引入甲基,能增加二芳基乙烯类化合物体系对氧的稳定性,与实验结果一致.2,3-二芳基马来酸酐化合物的闭环结构的LUMO和HOMO能隙小于开环结构的能隙,说明闭环结构的最大吸收波长大于开环结构的最大吸收波长,与实验结果一致.     

磺化金属萘酞菁聚集倾向的光谱研究

在磺化金属萘酞菁的荧光光谱和电子吸收光谱的Q谱带上观察到激基缔合物的荧光光谱峰和基态聚集物的吸收光谱峰。荧光光谱和吸收光谱实验说明 ,溶液中聚体分子和单体分子同时存在 ;聚体放出或吸收光子后都解离为单体 ;在荧光光谱中金属萘酞菁的激基缔合物荧光峰相对于单体荧光峰发生红移 ,在吸收光谱中金属萘酞菁基态聚集体的吸收峰相对于单体吸收峰发生蓝移 ,聚集体的荧光光谱和吸收光谱有镜像对称关系。磺化萘酞菁钴浓度较大时 ,其荧光光谱的猝灭较大。