Crystallization kinetics of poly(trimethylene terephthalate)

The isothermal crystallization kinetics of poly(trimethylene terephthalate) (PTT) have been investigated using differential scanning calorimetry (DSC) and polarized light microscopy (PLM). Enthalpy data of exotherm from isothermal crystallization were analyzed using the Avrami theory. The average value of the Avrami exponent, n, is about 2.8. From the melt, PTT crystallizes according to a spherulite morphology. The spherulite growth rate and the overall crystallization rate depend on crystallization temperature. The increase in the spherulitic radius was examined by polarized light microscopy. Using values of transport parameters common to many polymers (U* = 1500 cal/mol, T_∞= T_g − 30 °C) together with experimentally determined values of T (248 °C) and T_g (44 °C), the nucleation parameter, k_g, for PTT was determined. On the basis of secondary nucleation analyses, a transition between regimes III and II was found in the vicinity of 194 °C (ΔT ≅ 54 K). The ratio of k_g of these two regimes is 2.1, which is very close to 2.0 as predicted by the Lauritzen–Hoffman theory. The lateral surface‐free energy, σ = 10.89 erg/cm² and the fold surface‐free energy, σ_e = 56.64 erg/cm² were determined. The latter leads to a work of chain‐folding, q = 4.80 kcal/mol folds, which is comparable to PET and PBT previously reported. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 934–941, 2000     

Self-assembly architecture of bis(guanidiniums) receptors incorporated by sulfate anions in single crystals

A novel bis(guanidiniums)receptor for the catalytic cleavage of phosphosdiester was prepared and self-assembly architecture through hydrogen bonds and electrostatic interactions a-mong the bis(guanidiniums)receptor,the sulfate anion and water molecule was revealed by X-ray crystallographic analy-     

Synthesis reactivity and electrochemical properties of substituted cyclopentadienyl cobalt (III) complexes

Cyclopentadienyl cobalt complexes (η⁵‐C₅H₄R) CoLI₂ [L = CO,R=‐COOCH₂CH=CH₂ (3); L=PPh₃, R=‐COOCH₂‐CH=CH₂ (6); L=P(p‐C₆H₄O₃)₃, R = ‐COOC(CH₃) = CH₂ (7), ‐COOCH₂C₆H₅ (8), ‐COOCH₂CH = CH₂ (9)] were prepared and characterized by elemental analyses, ¹H NMR, ER and UV‐vis spectra. The reaction of complexes (η⁵‐C₅H₄R)CoLI₂ [L= CO, R= ‐COOC(CH₃) = CH₂ (1), ‐COOCH₂C₆H₅(2); L=PPh₃, R=‐COOC (CH₃) = CH₂ (4), ‐COOCH₂C₆H₅ (5)] with Na‐Hg resulted in the formation of their corresponding substituted cobaltocene (η⁵‐C₅H₄R)₂ Co[R=‐COOC(CH₃) = CH₂ (10), ‐COOCH₂C₆H₅ (11)]. The electrochemical properties of these complexes 1–11 were studied by cyclic voltammetry. It was found that as the ligand (L) of the cobalt (III) complexes changing from CO to PPh₃ and P(p‐tolyl)₃, their oxidation potentials increased gradually. The cyclic voltammetry of α,α′‐substituted cobaltocene showed reversible oxidation of one electron process.     

Molecular building blocks for solid‐state chalcogenides: solvothermal synthesis of [Mn(en)3]Te4 and [Fe(en)3]2(Sb2Se5)

Two new molecular metal chalcogenides, tris­(ethyl­enedi­amine‐N,N′)­manganese(II) tetratelluride, [Mn(C₂H₈N₂)₃]Te₄, (I), and bis­[tris­(ethyl­enedi­amine‐N,N′)­iron(II)] penta­seleno­diantimonate(III), [Fe(C₂H₈N₂)₃]₂(Sb₂Se₅), (II), containing the isolated molecular building blocks Te₄^2? and Sb₂Se₅^4?, have been synthesized by solvothermal reactions in an ethyl­enedi­amine solution at 433 K. The anion Te₄^2? in (I) is a zigzag oligometric chain with Te—Te bond lengths in the range 2.709–2.751 Å. There is a very short contact [3.329 (1) Å] between a pair of neighboring Te₄^2? anions. In (II), each Sb atom is surrounded by three Se atoms to give a tripodal coordination. One of the three independent Se atoms is a μ₂‐bridging ligand between two Sb atoms; the other two are terminal.     

A Novel Preprocessing Algorithm for Three-Way HPLC Data

Orthogonal signal correction (OSC) was a data preprocessing algorithm. It ensured that the filtered information was irrelevant to concentration data while using it to filter the noise from the original data. This paper extended the OSC application range from two-way data to three-way data. Two drug data sets, Enoxacin, Norfloxacin, Ciprofloxacin and Betamethasone, cortisone acetate, prednisone acetate, showed that the application of the OSC algorithm to three-way HPLC data was feasible and needed further research.     

A new class of aromatic polybenzoxazoles containing ortho-phenylenedioxy groups

A series of poly(o-hydroxy amide)s having both ether and ortho-catenated phenylene unit in the main chain were synthesized via the low-temperature solution polycondensation of 4,4^′-(1,2-phenylenedioxy)dibenzoyl chloride and 4,4^′-(4-tert-butyl-1,2-phenylenedioxy)dibenzoyl chloride with three bis(o-aminophenol)s including 4,4^′-diamino-3,3^′-dihydroxybiphenyl, 3,3^′-diamino-4,4^′-dihydroxybiphenyl, and 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane. The poly(o-hydroxy amide)s exhibited inherent viscosities in the range of 0.23-0.96 dl/g. Most of the poly(o-hydroxy amide)s were soluble in polar organic solvents such as N,N-dimethylacetamide (DMAc) and N-methyl-2-pyrrolidone (NMP) and could afford flexible and tough films by solution casting. Subsequent thermal cyclodehydration of the poly(o-hydroxy amide)s afforded polybenzoxazoles. However, the polybenzoxazoles were organic-insoluble except for those with the hexafluoroisopropylidene group. The polybenzoxazoles exhibited glass-transition temperatures (T_g) in the range of 200-232 °C by DSC and softening temperatures (T_s) of 250-256 °C by thermomechanical analysis. Thermogravimetric analyses indicated that most polybenzoxazoles were stable up to 500 °C in air or nitrogen. The 10% weight loss temperatures were recorded in the ranges of 546-606 °C in air and 574-631 °C in nitrogen.     

尼古丁是脂肪酶的反竞争抑止剂的实验研究

希望明确尼古丁对脂肪酶活性是否有抑止作用,用于解释医学已有统计数据：吸烟的人体重普遍较轻,而戒烟后体重会有回升．用三油酸甘油酯为底物,在加入尼古丁前后,检测脂肪酶活性变化．结果表明：脂肪酶在人体外仍有活性,而且尼古丁是脂肪酶反竞争性抑止剂．在脂肪酶浓度为7mg／mL时,抑止程度达50％．     

纳米金修饰玻碳电极固载抗体电位型白喉类毒素免疫传感器的研究

将巯基乙胺 (AET)固载到玻碳电极 (GCE)表面 ,进而化学吸附纳米金 (NG) ,并通过半胱氨酸 (Cys)用戊二醛 (GA)作交联剂将白喉抗体 (anti Diph)固定在玻碳电极上 ,从而制得高灵敏电位型白喉类毒素 (Diph)免疫传感器 .通过循环伏安法考察了电极表面的电化学特性 ,并对该免疫传感器的性能进行了详细的研究 .该传感器对白喉类毒素检测的线性范围是 2 4～ 60 0ng·mL-1,斜率为 3 8.9mV/decade ,线性相关系数为 0 .9979,检出限为 5 .2ng·mL-1,并将其用于生物制品中白喉类毒素的检测 ,其结果令人满意