Structure and order of the discotic compound 2,3,6,7,10,11-hexakispentyloxytriphenylene as revealed by diffraction and molecular simulation studies

The aggregate structure of the discotic compound 2,3,6,7,10,11-hexakispentyloxytriphenylene (HPT) was studied both for the crystalline state and the liquid crystalline state by using electron crystallography and a molecular simulation approach. In the crystalline state, HPT was found to adopt an orthorhombic P-2212 space group with cell parameters a = 36.73 Angstrom, b = 27.99 Angstrom and c = 4.91 Angstrom. Molecular packing calculations were conducted to elucidate the molecular conformation and mutual orientational characteristics in the different states. Phase transitions and relationships are discussed from a structural point of view.

The crystal structure and drawing-induced polymorphism in poly(aryl ether ketone)s .1. Poly(oxybiphenyl-4-4'-diyloxy-1,4-phenylenecarbonyl-1,3-phenylenecarbonyl-1,4-phenylene)

Crystal structure and polymorphism induced by uniaxial drawing of a poly(aryl ether ketone) [PEDEKmK] prepared from 1,3-bis(4-fluorobenzoyl)benzene and biphenyl-4,4'-diol have been investigated by means of transmission electron microscopy (TEM), electron diffraction (ED), wide-angle X-ray diffraction (WAXD), and differential scanning calorimetry (DSC) techniques. The melting and recrystallization process in the temperature range of 250-260 degrees C, far below the next melting temperature (306 degrees C), was identified and found to be responsible for the remarkable changes in lamellar morphology. Based on WAXD and ED patterns, it was found that crystal structure of isotropic-crystalline PEDEKmK obtained under different crystallization conditions (melt-crystallization, cold-crystallization, solvent-induced crystallization, melting-recrystallization, and crystallization from solution) keeps the same mode of packing, i.e., a two-chain orthorhombic unit cell with the dimensions a = 0.784 nm, b = 0.600 nm, and c = 4.745 nm (form I). A second crystal modification (form II) can be induced by uniaxial drawing above the glass transition temperature, and always coexists with form I. This form also possesses an orthorhombic unit cell but with different dimensions, i.e., a = 0.470 nm, b = 1.054 nm, c = 5.064 nm. The 0.32 nm longer c-axis of form II as compared with form I is attributed to an overextended chain conformation due to the expansion of ether and ketone bridge bond angles during uniaxial drawing. The temperature dependence of WAXD patterns for the drawn PEDEKmK suggests that form II can be transformed into the more stable form I by relaxation of overextended chains and relief of internal stress at elevated temperature in absence of external tension.

THE CHARGE-DISTRIBUTION AND THE ELECTRIC-FIELD GRADIENT IN THE HIGH-TEMPERATURE SUPERCONDUCTOR TLBA2CAN-1CUNO2N+3 (N = 1 TO 3)

The net charges at atoms in the high-temperature superconductor TlBa2Can-1CunO2n+3 (n = 1 to 3) are calculated by means of the tight-binding approximation based on the EHMO method. The results indicate that the charge distribution in this kind of compounds possesses a specially layered arrangement. An insulating Ba-Ba layer is inserted between the Cu-O layer and the Tl-O layer. There may exist a weak coupling between the Cu-O layer and the Tl-O layer through the interaction of the same O(2) atom with both the Cu atom and the Tl atom. The existence of the Ca in the compounds can cause the valence fluctuation at the Cu atom. The calculated electric field gradients at atoms implies that the conducting electron or hole may move in the Cu-O layer, which is closest to the Tl-O layer, along the a-b plane.

Er_(3x)~(3+):Y_(3-3x)Al_5O_(12)和Er_x~(3+)Yb_(1-x)P_5O_(14)晶体的光谱强度参数

本文报道了用J-O理论计算的Er_(3x)~(3+):Y_(3-3x)A_5O_(12)和Er_x~(3+)Yb_(1-x)P_5O_(14)两种晶体中Er~(3+)五种浓度的振子强度、Ω_λ参数、辐射跃迁几率与荧光分支比。并观察了这些参数的变化规律。

4-(2-Hydroxybenzylideneamino)-3-(1H-1,2,4-triazol-1-ylmethyl)-1H-1,2,4-triazole-5(4H)-thione

In the title compound, C12H11N7OS, the dihedral angles made by the thione-substituted triazole ring with the other triazole ring and the benzene ring are 71.56 (2) and 47.89 (3)degrees, respectively. Inter- and intramolcular hydrogen-bond interactions stabilize the structure.

4-(4-chlorobenzylideneamino)-3-(1H-1,2,4-triazol-1-ylmethyl)-1H-1,2,4-triazole-5(4H)-thione

In the title compound, C12H10ClN7S, the dihedral angles made by the plane of the thione-substituted triazole ring with the planes of the other triazole ring and the benzene ring are 73.57 (3) and 46.65 (2)degrees, respectively. Inter-and intramolcular hydrogen bonds and pi-pi stacking interactions stabilize the structure.

基于3自由度并联机器人的船载炮6维运动模拟系统

本文系统基于3自由度并联机器人和3维图形仿真实现了空间6维运动的模拟，构造了一种3自由度并联机构来模拟船的3维转动，并给出了并联平台的运动学逆解，采用图形仿真虚拟作战环境，模拟船的3维移动，并分析了图形驱动原因。

土的本构模型及其工程应用

第一章 绪论
1、1土的本构特性
1、2土本构模型的发展简史
1、3土本构模型的研究动向
2、1应力分析
第二章 连续介质力学的基本概念
2、1、1一点的应力状态、应力张量
2、1、2Cauchy公式、求和协定
2、1、3主应力
2、1、4偏应力
2、1、5八面体应力、纯剪应力、主剪应力
2、1、6应力空间、应力路径
2、1、7应力Mohr圆和应力Lode参数
2、2应变分析
2、2、1一点的应变状态、应变张量
2、2、2应变Cauchy公式
2、2、3主应变
2、2、4偏应变
2、2、5八面体应变、纯应变、主剪应变
2、2、6应变空间、应变路径
2、2、7应变率张量、应变增量张量
2、2、8应变Mohr圆
2、2、9有限应变
2、3基本方程
2、3、1连续方程
2、3、2运动微分方程
2、3、3协调方程
2、3、4能量方程
2、3、5本构方程
2、3、6边界条件和初始条件
第三章 经典塑性理论简述
3、1屈服准则
3、1、1初始屈服
3、1、2后继屈服
3、1、3几种屈服条件
3、2加载和卸载准则
3、2、1理想塑性材料的加载和卸载
3、2、2硬化材料的加载和卸载准则
3、3硬化规律
3、3、1各向同性硬化模型
3、3、2随动硬化模型
3、3、3混合硬化模型
3、4塑性公设
3、4、1Drucker塑性公设
3、4、2Ильюшин塑性公设
3、5流动规则
3、5、1塑性位势理论的基本概念
3、5、2流动规则
3、6塑性形变理论与塑性增量理论
3、6、1塑性形变理论
3、6、2塑性增量理论
第四章 土的弹性本构模型
4、1线弹性模型
4、1、1广义Hook定律
4、1、2正交各向异性线弹性体
4、1、3横观各向同性线弹性体
4、1、4各向同性线弹性体
4、2应变能和应变余能
4、3能量正定性与弹性材料稳定性
4、4具有割线模量的非线性弹性模型
4、4、1全量型应力—应变关系
4、4、2增量型应力—应变关系
4、5Cauchy弹性模型
4、5、1全量型Cauchy弹性模型应力—应变关系
4、5、2增量型Cauchy弹性模型应力—应变关系
4、6超弹性模型
4、6、1全量型超弹性模型应力—应变关系
4、6、2增量型超弹性模型的应力—应变关系
4、7次弹性模型
4、8结语
5、1本构关系的普遍表达式
第五章 土的弹性—理想塑性模型
5、2本构模型中材料常数的确定
5、3本构模型的数值计算
5、4Prandtl—Reuss模型
5、5Drucker—Prager模型
5、6Coulomb模型
6、1本构关系的普遍表达式
第六章 土的弹性—硬化塑性模型
6、2剑桥模型
6、3修正剑桥模型
6、4Lade—Duncan模型
6、5帽盖模型
6、5、1一般增量应力—应变关系与刚度矩阵的推导
6、5、2模型的拟合过程
6、5、3帽盖模型的数值计算
第七章 土的粘弹塑性模型
7、1土的流变学基本模型
7、2Maxwell体模型
7、3Kelvin体模型
7、4粘塑性体模型
7、5三元模型
7、6多元件组合模型
8、1弹塑性横观各向同性模型
第八章 土本构模型的近期发展
8、2非线性弹性—硬化塑性帽盖模型
8、3弹/粘塑性动态帽盖模型
8、4多重屈服面模型
8、5边界面模型
8、6内时本构方程
9、1基础的沉降与塌陷
第九章 土本构模型在工程中的应用
9、1、1具有不同材料常数的Drucker—Prager模型
9、1、2具有非相关联流动的Drucker—Prager模型
9、1、3具有相关流动的帽盖模型
9、2堤坝的非线性分析
9、3基坑开挖的非线性分析
9、3、1基坑竣工后状况
9、3、2边坡对地震过程的响应
9、3、3地震后的滑移
参考文献

Upconversion emissions in Yb3+-Tm3+-doped tellurite glasses excited at 976 nm

Intense Tm3+ blue upconversion emission has been observed in Tm3+-Yb3+ codoped oxyfluoride tellurite glass under excitation with a diode laser at 976 nm. Three emission bands centered at 475, 650 and 796 nm corresponding to the transitions (1)G(4) -> H-3(6), (1)G(4) -> H-3(4) and F-3(4) -> H-3(6), respectively, simultaneously occur. The dependence of upconversion intensities on Tm3+ ions concentration and excitation power are investigated. For fixed Yb2O3 concentrations of 5.0 mol%, the maximum upconversion intensity was obtained with Tm2O3 concentration of about 0.1 mol%. The blue upconversion luminescence lifetimes of the Tm3+ transitions (1)G(4) -> H-3(6) are measured. The results are evaluated by the possible upconversion mechanisms.