热定型聚酯纤维内应力与晶格变形的关系

<正> 结晶学家认为低分子物结晶虽可能存在一定缺陷和变形,但一般都具有一定的晶胞参数。这一概念对于高分子物结晶已不再正确。Bosley认为成形、热处理、冷却速率和杂质的存在皆可引起晶格变形;Fakirov故意在PET中加入少量杂质,却未引起变形。至今,PET已累积了7组晶胞参数,8个计算所得的晶区密度显示了较大幅度的波动(见     

高纯度植酸的制备

高纯度植酸的制备孙定光胡佩廖显威（四川师范大学化学系成都６１００６６）关键词植酸制备高纯试剂中图分类号Ｏ６２９．９植酸（ＰｈｙｔｉｃＡｃｉｄ）又名肌醇六磷酸酯，分子式：Ｃ６Ｈ１８Ｏ２４Ｐ６，结构为植酸是中等强度的有机酸，因其结构特殊，具极强的螯合作用...     

光谱复杂的稀土基体中稀土杂质ICP光谱测定的一些问题

ICP激发光源以其独特的功能使ICP/AES技术在稀土分析中的应用日益广泛,在一定程度上取代了经典的直流电弧光谱法,但应指出,由于常规雾化器的低雾化效率(≤5％)和试样的高倍稀释,ICP/AES技术的实际检测能力的改善并不明显,本文用ICP光谱法测定了     

Modified modeling of the effect of pH and viscosity on the mass transfer in hydrophobic hollow fiber membrane contactors

This paper studied the effect of pH and the viscosity of feed solution on the mass transfer in two different specifications of hydrophobic hollow fiber membrane contactors. Experimental results showed that the pH of the feed had a significant effect on the rate of mass transfer, the flux and the removal efficiency of easily ionized volatile compounds (VCs), such as ammonia. In unbuffered feed solutions, both the resistance of membrane and the resistance of feed side were affected by the pH of feed and both of them had contributions to the overall mass transfer. A model, , was proposed to predict the effect of pH and gave good agreement with the experimental data for the two contactors. The relationship between viscosities and the mass transfer coefficient could be described by . Based on our experiments, the change of the viscosities in the concentration range of ammonia from 50 to 10,000 mg l⁻¹ caused about 3–4% variation of the mass transfer coefficients. Moreover, it may be more suitable to use the equilibrium concentrations of volatile species instead of the total concentrations of VCs to estimate mass transfer coefficients, removal efficiency and flux. Experimental results also revealed that the choice of the pH of feed might be one of the most crucial factors for removing easily ionized VCs, such as ammonia, from water and wastewater.     

C9‐Iridoids from Scrophularia buergeriana

Four new iridoids, buergerinins B–E ( 1 – 4 ), along with three known iridoids, were isolated from the roots of Scrophularia buergeriana. Their structures were identified on the basis of spectroscopic analysis.     

Microwave-accelerated derivatization processes for the determination of phenolic acids by gas chromatography-mass spectrometry

A rapid method for the derivatization of phenolic antioxidants using microwave irradiation has been developed. Six antioxidatively active phenolic components of wines and fruits, namely gallic acid, gentisic acid, vanillic acid, caffeic acid, ferulic acid and p-coumaric acid were used in the model study. The solution of phenolic acids was evaporated to dryness on a rotary evaporator followed by further drying under microwave irradiation (600 W, 30 s). The resultant residue was dissolved in pyridene and treated with bis(trimethylsilyl)acetamide while irradiated by microwave using high power for 30 s. Controlled reaction was carried out employing bis(trimethylsilyl)trifluoroacetamide under conventional heating for 30 min. The trimethylsilyl derivatives were identified and quantified on a gas chromatography/mass selective detector. The mass spectral fragmentation patterns of the derivatives obtained by microwave irradiation were identical to those prepared by heating. The yields of microwave-assisted silylation were comparable to those from conventional heating. The rsd were less than 8% for six replicates. The linearity in wine matrix was nearly perfect. This method is a useful protocol to examine the phenolic constituents in wines and agricultural products.     

反相高效液相色谱法的多波长同时测定预混合饲料中的脂溶性维生素A，α－E，D_3，K_3

反相高效液相色谱法的多波长同时测定预混合饲料中的脂溶性维生素Ａ，α－Ｅ，Ｄ＿３，Ｋ＿３李桂凤，李缙扬，郝征红，聂燕，孟兆宏，李学春（山东省农业科学院中心实验室济南２５０１００）１前言对脂溶性维生素的分析，被许多国内外分析专家认为是高难度的分析项目。本...     

液芯光纤光度法在乙醇水溶液中测定铂(Ⅱ)、钛(Ⅳ)

采用氟塑料长光纤管，以４２％乙醇水溶液作液芯，组成液芯光纤，基于铂与氯化亚锡、钛与过氧化氢形成黄色络合物在乙醇水溶液中很稳定，拟定了测定铂、钛的液芯光纤光度法。该法灵敏度高，用 １ｍ长光纤作吸收池，铂的灵敏度为 ４． ８４５ Ａ／ｍｇ· Ｌ－１，钛的灵敏度为１．４１Ａ／ｍｇ· Ｌ－１（Ａ为吸光度），与常规法（１ｃｍ）比色皿相比灵敏度提高了 １００倍。该法测定了催化剂中铂，煤灰粉中钛，结果与推荐值相符。     

Comparative X-ray photoelectron spectroscopic study on the desulfurization of thiophene by Raney nickel and rapidly quenched skeletal nickel

The desulfurization of thiophene on Raney Ni and rapidly quenched skeletal Ni (RQ Ni) has been studied in ultrahigh vacuum (UHV) by X-ray photoelectron spectroscopy (XPS). The Raney Ni or RQ Ni can be approximated as a hydrogen-preadsorbed polycrystalline Ni-alumina composite. It is found that thiophene molecularly adsorbs on Raney Ni or RQ Ni at 103 K. At 173 K, thiophene on alumina is desorbed, while thiophene in direct contact with the metallic Ni in Raney Ni undergoes C-S bond scission, leading to carbonaceous species most probably in the metallocycle-like configuration and atomic sulfur. On RQ Ni, the temperature for thiophene dissociation is about 100 K higher than that on Raney Ni. The lower reactivity of RQ Ni toward thiophene is tentatively attributed to lattice expansion of Ni crystallites in RQ Ni due to rapid quenching. The existence of alumina and hydrogen may block the further cracking of the metallocycle-like species on Raney Ni and RQ Ni at higher temperatures, which has been the dominant reaction pathway on Ni single crystals. By 473 K, the C 1s peak has disappeared, leaving nickel sulfide on the surface.