Synthesis and characterization of novel polyimides with 2,2‐bis[4(4‐aminophenoxy)phenyl]phthalein‐3′,5′‐bis(trifluoromethyl)anilide

2,2‐Bis[4(4‐aminophenoxy)phenyl]phthalein‐3′,5′‐bis(trifluoromethyl)anilide (6FADAP), containing fluorine and phthalimide moieties, was synthesized via the Williamson ether condensation reaction from 1‐chloro‐4‐nitrobenzene and phenolphthalein‐3′,5′‐bis(trifluoromethyl)anilide, which was followed by hydrogenation. Monomers such as 2,2‐bis[4(4‐aminophenoxy)phenyl]phthalein‐anilide containing phthalimide groups and 2,2‐bis[4(4‐aminophenoxy)phenyl]phthalein containing only phthalein moieties were also synthesized for comparison. The monomers were first characterized by Fourier transform infrared (FTIR), ¹H NMR, ¹⁹F NMR, elemental analysis, and titration and were then used to prepare polyimides with 2,2‐bis(3,4‐dicarboxyphenyl)hexafluoropropane dianhydride. The polyimides were designed to have molecular weights of 20,000 g/mol via off‐stoichiometry and were characterized by FTIR, NMR, gel permeation chromatography (GPC), differential scanning calorimetry, and thermogravimetric analysis. Their solubility, water absorption, dielectric constant, and refractive index were also evaluated. The polyimides prepared with 6FADAP, containing fluorine and phthalimide moieties, had excellent solubility in N‐methylpyrrolidinone, N,N‐dimethylacetamide, tetrahydrofuran, CHCl₃, tetrachloroethane, and acetone, and GPC analysis showed a molecular weight of 18,700 g/mol. The polyimides also exhibited a high glass‐transition temperature (290 °C), good thermal stability (～500 °C in air), low water absorption (1.9 wt %), a low dielectric constant (2.81), a low refractive index, and low birefringence (0.0041). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3361–3374, 2003     

Coriolis耦合对Cl+H2→H+HCl非绝热反应的影响

使用含时波包方法 ,在Capecchi和Werner拟合的非绝热耦合势能面上 ,研究了Cl处在自旋轨道基态以及自旋轨道激发态时与H2 反应的活性 ,并且讨论了Coriolis耦合的影响 .计算了某些角动量时的反应几率 .计算结果显示 ,当Cl原子处在自旋轨道激发态与处在基态的H2 的反应活性很小 ,Coriolis耦合在这个反应中起了很小的作用 .     

Rigorous results in selection of steady needle crystals

This paper concerns the existence of solutions to a steady needle crystal growth problem in a one-sided model. We rigorously prove that for small nonzero anisotropy γ, analytic symmetric needle crystal solutions exist in the limit of surface tension ε² if only if the stokes constant S for a relatively simple nonlinear differential equation is zero. This Stokes constant S depends on the parameter β=2^9/7γε^−8/7 and earlier numerical calculations by a number of investigators have shown this to be zero for a discrete set of values of β. It is also proven that for γ=0, there can be no symmetric needle crystal solution in the considered space.The methodology consists of two steps. First, the original problem is reduced to a weak half-strip problem for any γ in a compact set of [0,1) by relaxation of the symmetry condition. The weak problem is shown to have a unique solution in the function space considered for any γ∈[0,γ_m] for some γ_m>0. When a symmetry is invoked, the weak problem is shown equivalent to the original needle crystal problem. Next, by considering the behavior of the solution in neighborhood of an appropriate complex turning point for γ∈(0,γ_m], we extract an exponentially small term in ε as ε→0⁺ that generally violates the symmetric condition. We prove that the symmetry condition is satisfied for small ε when the parameter β is constrained appropriately.     

A Mossbauer study of the magnetic coupling in iron phosphorous trisulfides

The polycrystalline sample of layered compound FePS_3 has been investigated by using M?ssbauer spectroscopy (12K to 300K), magnetic susceptibility measurements, x-ray diffraction and FTIR spectroscopy. The antiferromagnetic order exists below T_N=120.5±1K. The M?ssbauer spectra below T_N indicate that the magnetization axis is perpendicular to the layer of FePS_3, and the divalent iron cations are in their high spin configurations. By fitting the hyperfine field parameters near the Néel temperature, we obtain information on the nature of magnetic interactions in the material. The results show that the magnetic coupling can be treated by the two-dimensional Ising model, and it can be interpreted on the basis of a crystal-field effect.     

Rigid nitronyl-nitroxide-labelled anchoring molecules: syntheses, structural and magnetic investigations

The syntheses of two rigid organic molecular rods bearing a nitronyl-nitroxide radical and a terminal nitrogen-based functionality like a pyridine or a cyano group are reported. Both new paramagnetic molecules are fully characterized, including crystal structure analysis. Furthermore their magnetic behaviours in the crystalline state are investigated and their spin concentration corroborate their excellent purity. While the pyridine functionalized rod is synthesized by converting the corresponding benzaldehyde to the phenyl-nitronyl-nitroxide radical, the synthesis of the cyano functionalized rod demonstrates the accessibility of highly sophisticated spin-labelled molecules via cross-coupling reaction with a meta-iodo-phenyl-nitronyl-nitroxide moiety.     

磁光玻璃光纤的偏振特性及其在全光纤电流传感器中的应用

在磁光玻璃裸光纤偏振特性研究的基础上，研制磁光玻璃光纤，偏振特性及其在全光纤电流传感器中的应用。将采用模管法拉制成的磁光玻璃光纤置于亥姆霍兹线圈产生的磁场中，当线偏振光通过该光纤时，其偏振面旋转一定角度，把该角度转换成光信号的强度，然后再用仪器进行检测。通过对线偏振光偏振面在磁场中的偏振特性的测试与实验，提出用磁光玻璃光纤构成的全光纤电流传感器，可用于电流和磁场测试。     

Theory of optical couplers

The propagation of solitons through optical couplers is studied here in this paper. Both the twin-core couplers as well as the multiple-core couplers are considered here in this paper. The parameter dynamics of the solitons that are governed by the coupled generalized nonlinear Schrodinger's equation, due to non-Kerr law nonlinearity, has been obtained for such couplers.     

将SVRT模型应用到单原子多原子反应F+CH2D2→CH2D/CHD2+DF/HF中

由于含时波包方法具有经典的直观又不乏量子力学的准确 ,选择含时波包方法来处理F +CH2 D2 →CH2 D/CHD2 +DF/HF反应 .把半刚性振转子 (SVRT)模型应用到该反应体系中 ,研究了两个通道中该反应从基态反应物开始在修正过的J1(MJ1)势能面上计算出来了反应几率、积分截面、速率常数 .反应几率随能量变化的图的数值结果给出了振荡结构 ,这些振荡结构是可以和动力学振荡联系起来的 .而这些振荡结构在积分截面随着能量变化的图中就被反应几率求和后的平均结果所掩盖了 .速率常数和实验结果的比较也得到了较好的结果 .     

溶液中CO…CO+体系相互作用的理论研究

在B3LYP/6-311+G水平上利用SCRF方法中的Onsager model模型考察了CO…CO+体系在两种介质(水和苯)中可能存在的相互作用复合物,发现由于H2O与CO+之间存在较强的相互作用,在水中仅能存在一种稳定结构,而在苯溶液中存在三种稳定的复合物.通过消除基函数引起的叠加误差(BSSE)和零点振动能(ZPVE)的校正,精确求算出三种复合物在两种介质中的相互作用能,表明溶剂的性质对复合物的稳定性有着重要的影响.     

K＋－SrO－La_2O_3／ZnO催化剂上甲烷氧化偶联反应Ⅰ．催化活性和反应气中添加CO_2的影响

Ｋ＋┐ＳｒＯ┐Ｌａ２Ｏ３／ＺｎＯ催化剂上甲烷氧化偶联反应＊Ⅰ．催化活性和反应气中添加ＣＯ２的影响余林徐奕德＊＊郭燮贤（中国科学院大连化学物理研究所催化基础国家重点实验室，大连１１６０２３）关键词钾离子，氧化锶，氧化镧，氧化锌，金属氧化物催化剂，甲烷，...