6291型热变形温度和维卡软化温度测试仪的校准及故障排除

介绍6291型热变形温度和维卡软化温度测试仪的温度校准和位移校准方法，对测试仪的一些常见故障，例如电源故障，主温度传感器故障，电加热系统控制单元故障及测试站的温度偏差较大等进行了分析，并给出了排除故障的方法。     

超高感彩卷乳剂微晶体电镜研究

应用物理和化学相结合的方法，将超高感彩卷分层剥离，离心沉降，水洗除胶，电镜观测各层乳剂的微晶体结构。揭示了超高感彩卷各乳剂层的结构情况，披露了超高感彩剂制造技术。     

L-谷氨酸、甘氨酸二元、三元体系中铽(Ⅲ)、钙(Ⅱ)的化学形态研究

在模拟生理条件下 (37℃ ,I=0 .1 5mol/ L Na Cl) ,用 p H电位法研究了铽 ( )、钙 ( )与 L-谷氨酸、甘氨酸二元、三元体系。确定了体系存在的物种 ,测定了体系中配合物的稳定常数。讨论了上述二元、三元体系中铽 ( )、钙 ( )的物种分布特点。     

关于气相渗透法仪器常数对分子量的依赖性

在热敏电阻装置不同的两种仪器上,对分子量为178—716的九种纯化合物,在苯、氯仿和丁酮中,和几个温度下测定了VPO仪器常数K值,在此分子量范围内,K值是常量。为了研究仪器结构对测试结果的影响,对分子量为1200—3.5×10~4的几个聚合物进行测试,所得结果很接近,并发现达到稳态所需时间和溶剂性质有明显的关系。     

Synthesis of diethers derived from furoin by phase transfer catalysis under microwave irradiation

A series of new diethers were obtained by alkylation of furoin under microwave irradiation (MWI) in phase transfer catalysis (PTC) conditions. The products of alkyl halides were synthesized in good yields (>75%) within a few minutes, and the products of dihalides were synthesized in fair yields (about 45%). The yields are dramatically improved compared to conventional heating under the same conditions, in spite of similar profiles of rising in temperature.     

Synthesis and crystallization kinetics of the novel ion exchanger Na<Subscript>4</Subscript>Ti<Subscript>4</Subscript>Si<Subscript>3</Subscript>O<Subscript>10</Subscript> for cesium removal

Thermodynamics and crystallization kinetics of the hydrothermal synthesis of Na₄Ti₄Si₃O₁₀ (NaTS) were systemically studied by both experiments and model simulation. Experimental results showed that the curve of crystallinity with time was a characteristic signmoid in the shape that indicated the crystallization of Na₄Ti₄Si₃O₁₀ was a typical spontaneous nucleation process on the laboratory scale. Crystallization of NaTS belongs to the liquid-liquid transformation mechanism and the reaction is endothermic (ΔH = 15.3 kJ/mol). A mathematic model of crystallization kinetics was developed to simulate the synthesis of NaTS. Runge-Kutta and simplex methods were adopted to solve the partial differential equations. Model results fitted well with the experimental data and showed that the synthesis process belongs to spontaneous nucleation and crystal growth. Moreover, the very small crystal growth constant (5.6·10⁻⁷) and gel dissolution constant (7.0·10⁻⁷) indicate they are the rate-limiting steps of the whole synthesis process.     

Groups of paramagnetic centres in coal samples with different carbon contents

Complex systems of paramagnetic centres existing in demineralised flame coal (71.4 wt% C), medium-rank coal (85.6 wt% C) and anthracite (94.9 wt% C) were analysed by electron paramagnetic resonance spectroscopy (EPR). Different groups of paramagnetic centres were searched in macerals (exinite, vitrinite, inertinite) of coals with carbon contents of 73.8 wt% C and 85.6 wt% C. Experimental EPR spectra were fitted by different superposition of theoretical lines. Total concentration of paramagnetic centres both in coal and macerals increases with carbon content in the sample. Total concentration of paramagnetic centres in macerals increases from exinite to inertinite. Four groups of paramagnetic centres were found in medium-rank coal, and only two groups exist in flame coal and anthracite. The EPR spectrum of medium-rank coal is a superposition of two broad and two narrow lines. Both broad and narrow, and two narrow lines were measured in EPR spectra of flame coal and anthracite, respectively. Two types of paramagnetic centres with broad lines and one group with narrow lines exist in exinite and vitrinite from medium-rank coal. Two narrow components were observed in EPR spectra of its inertinite. Two different broad electron paramagnetic resonance signals were detected for macerals from low-coalificated coal. Paramagnetic centres systems of medium-rank coal samples reveal the most complex character. Broad EPR lines were not observed for the higher coalificated samples, i.e., anthracite and inertinite from medium-rank coal. Narrow lines do not occur in EPR spectra of low-coalificated macerals. Strong dipolar interactions and fast spin-lattice relaxation processes are characteristic for paramagnetic centres with broad lines. Strong exchange interactions and short spin-lattice relaxation time were measured for paramagnetic centres with the narrowest EPR signals.     

Oxidation of some catecholamines by sodium N-chloro-p-toluenesulfonamide in acid medium: A kinetic and mechanistic approach

The kinetics of the oxidation of five catecholamines viz., dopamine (A), L-dopa (B), methyldopa (C), epinephrine (D) and norepinephrine (E) by sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) in presence of HClO₄ was studied at 30±0.1 °C. The five reactions followed identical kinetics with a first-order dependence on [CAT] _o , fractional-order in [substrate] _o , and inverse fractional-order in [H⁺]. Under comparable experimental conditions, the rate of oxidation of catecholamines increases in the order D>E>A>B>C. The variation of ionic strength of the medium and the addition of p-toluenesulfonamide or halide ions had no significant effect on the reaction rate. The rate increased with decreasing dielectric constant of the medium. The solvent isotope effect was studied using D₂O. A Michaelis-Menten type mechanism has been suggested to explain the results. Equilibrium and decomposition constants for CAT-catecholamine complexes have been evaluated. CH₃C₆H₄SO₂NHCl of the oxidant has been postulated as the reactive oxidizing species and oxidation products were identified. An isokinetic relationship is observed with β=361 K, indicating that enthalpy factors control the reaction rate. The mechanism proposed and the derived rate law are consistent with the observed kinetics.     

Syntheses of (-)-TAN-2483A, (-)-massarilactone B, and the fusidilactone B ring system. Revision of the structures of and syntheses of (+/-)-Waol A (FD-211) and (+/-)-Waol B (FD-212)

The structure of waol A has been revised from 1 to 6, the vinylogue of TAN-2483A (5). Aldol reaction of hydroxybutanolides 13b,c with 2,4-hexadienal affords 12b,c, which are subjected to iodoetherification with bis(sym-collidine)IPF6 to provide 11b(c). Treatment with Et3N in CH2Cl2 completes the three-step syntheses of TAN-2483A (5) and waol A (6). Aldol reaction of hydroxybutanolide 31 with 2,4-hexadienal affords 32, which is subjected to iodoetherification to provide 34, which in turn is treated with Bu3SnCl, NaBH3CN, and oxygen to provide diol 60. Further elaboration completes the first syntheses of massarilactone B (7) and the fusidilactone B (9) ring system.     

植物样品中单宁的微波溶出快速测定法研究

研究了利用微波代替一般的沸水浴处理试样的方法。对不同植物样品中单宁的浸提测定，与常规方法做了对照，并讨论了微波功率、时间、酸度等因素对测定结果的影响。研究表明，此法可大大地缩短测定时间，提高测定效率，节省人力、物力，不污染环境，便于大批量样品的测定，相对标准偏差≤１．４％，测定结果较为满意。为植物样品中单宁的测定，提供了一个快速、简便、准确的分析方法，并可借鉴于其它样品的测定。