集成微管路离子选择电极功能块研究

本文对微型管状离子选择电极在流动条件下的电化学特征进行了研究,并设计了新的集成微管路离子选择以电极功能块。用此微型装置测定了土壤、血清、水和药物中的K~+、Na~+、pH、Cl~-、F~-、阿托品、东茛菪碱,并和各种标准方法作了比较,获得满意分析结果。     

Carboxylate anions binding and sensing by a novel tetraazamacrocycle containing ferrocene as receptor

A tetraazamacrocycle containing ferrocene moieties has been synthesized and characterized. The tetraprotonated form of this compound was evaluated as a receptor (R) for anion recognition of several substrates (S), Cl(-), PF(6)(-), HSO(4)(-), H(2)PO(4)(-) and carboxylates, such as p-nitrobenzoate (p-nbz(-)), phthalate (ph(2-)), isophthalate (iph(2-)) and dipicolinate (dipic(2-)). (1)H NMR titrations in CD(3)OD indicated that this receptor is not suitable for recognizing HSO(4)(-) and H(2)PO(4)(-), but weakly binds p-nbz(-), and strongly interacts with ph(2-), dipic(2-), and iph(2-) anions forming 1 : 2 assembled species. The largest beta(2) binding constant was determined for ph(2-), followed by dipic(2-) and finally iph(2-). The effect of the anionic substrates on the electron-transfer process of the ferrocene units of R was evaluated using cyclic voltammetry (CV) and square wave voltammetry (SWV) in methanol solution and 0.1 mol dm(-3)(CH(3))(4)NCl as the supporting electrolyte. Titrations of the receptor were undertaken by addition of anion solutions in their tetrabutylammonium or tetramethylammonium forms. The protonated ligand exhibits a reversible voltammogram, which shifts cathodically in the presence of the substrates. The data revealed kinetic constraints in the formation of the receptor/substrate entity for dipic(2-), ph(2-) and iph(2-) anions, but not for p-nbz(-). In spite of the slow kinetics of assembled species formation with the ph(2-) substrate, this anion provides the largest redox-response when the supramolecular entity is formed, followed by dipic(2-), iph(2-) and finally p-nbz(-) anions. This trend is in agreement with the (1)H NMR results and the values of the binding constants. Single crystal X-ray structures of the receptor with PF(6)(-), ph(2-), iph(2-) and p-nbz(-) were carried out and showed that supermolecules with a RS(2) stoichiometry are formed with the first three anions, but RS(4) with p-nbz(-). In all cases the binding occurs outside the macrocyclic cavity via N-H...O=C hydrogen bonds for carboxylate anions and N-H...F hydrogen bonds for the PF(6)(-) anion, which is in agreement with the solution results. The macrocyclic framework adopts different conformations in order to interact with each substrate having Fe...Fe intramolecular distances ranging from 10.125(14) to 12.783(15)A.     

以廉价国产化试剂合成大孔径高度有序介孔氧化硅分子筛

新一代大孔径（１～３０nm）介孔分子筛在大分子转化、吸附、生物大分子分离以及电磁、传感器、光电子等领域均具有广泛的应用前景犤１～４犦。由昂贵的长链有机季铵盐阳离子表面活性剂为模板合成的MCM－４１介孔分子筛，由于其孔径小，水热稳定性差，受到了较大的限制。与其相比，以嵌段高分子共聚物为模板剂合成的介孔分子筛SBA－１５具有孔径均一，有序度高，并且其孔径大以及水热性能良好等优点，近年来得到了广泛的研究犤５～９犦。其骨架上修饰有机硅烷，可用于重金属的分离、回收，以及蛋白质的控释与分离。利用主－客体方法在SB…     

Photocatalytic degradation of methylene blue on Fe3+-doped TiO2 nanoparticles under visible light irradiation

Fe³⁺-doped TiO₂ composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultravioletvisible spectroscopy (UV-Vis) diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of Fe³⁺/TiO₂ nanoparticles under visible light irradiation. The influence of doping amount of Fe³⁺ (ω: 0.00%–3.00%) on photocatalytic activities of TiO₂ was investigated. Results show that the size of Fe³⁺/TiO₂ particles decreases with the increase of the amount of Fe³⁺ and their absorption spectra are broaden and absorption intensities are also increased. Doping Fe³⁺ can control the conversion of TiO₂ from anatase to rutile. The doping amount of Fe³⁺ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The appropriate doping of Fe³⁺ can markedly increase the catalytic activity of TiO₂ under visible light irradiation. __________ Translated from Journal of Northwest Normal University (Natural Science), 2006, 42(6): 55–56 [译自: 西北师范大学学报(自然科学版)]     

Rank-1 approximation to the van der Waals interaction

We present and discuss a variational single-product approximation to the van der Waals dispersion interaction leading to a simple formula for C ₆ that seems capable to give more than 99% of the ‘exact’ value. The formula is derived from Hylleraas’ variational principle in the tensor product space of the interacting molecules and therefore enjoys bounding properties. The formula has been tested by computing the C ₆ dispersion constants of H–H, and, at Full CI level, of the following systems: He–He, He–Li, Li–Li, LiH–LiH, HF–HF. Connections with the London formula are discussed. Contribution to the Fernando Bernardi Memorial Issue.     

Synthesis,characterization, X-ray structural analysis and study of oxidative properties of propyltriphenylphosphonium bromochromate

The complex of propyltriphenylphosphonium bromochromate(VI), PrPh₃P[CrO₃Br] is easily synthesized in nearly quantitative yield using a direct reaction of chromium(VI) oxide and propyltriphenylphosphonium bromide. This compound is a versatile reagent for the efficient and selective oxidation of organic substrates, in particular for alcohols to their corresponding aldehydes or ketones, under mild conditions. This compound was characterized by IR, UV/Visible, ¹³C-n.m.r. and ¹H-n.m.r. techniques. It crystallized in the monoclinic form and its crystal and molecular structure have been determined by X-ray crystallography.     

Microwave synthesis,characterization and catalytic properties of titanium-incorporated ZSM-5 zeolite

Titanium-incorporated ZSM-5 zeolites (Si/Al = 50–200 and Si/Ti = 70) were successfully synthesized in a one-step sol-gel process under microwave irradiation. The characteristics of Ti-ZSM-5 zeolites were investigated using X-ray power diffraction, UV/Vis-DRS, FT-IR spectroscopy and solid-state ²⁷Al-NMR to monitor the physico-chemical properties. Simultaneously, the acidic properties were characterized by the NH₃-TPD profile. The characterization results revealed that the Ti⁴⁺ and Al³⁺ ions were well incorporated into the framework of Ti-ZSM-5 zeolite. The prepared zeolite was moderately active but selective in the dehydration of methanol to dimethyl ether.     

六味地黄丸的精细指纹图谱分析及模式识别分类研究

采用高效液相色谱建立了六味地黄丸的指纹图谱,对两个厂家的16批产品进行了测定,并结合中药相似度软件和主成分分析法对全指纹图谱和其精细指纹图谱进行了模式识别研究。结果表明,中药相似度软件能够对不同厂家的产品进行区分但也可能造成误判;在主成分分析法的投影图中,两个厂家的产品明显聚为两类,而且不同批次产品的差异也能够显示出来。     

反向流动注射化学发光法测定痕量铁

基于邻菲别名林对高碘酸钾－碱性鲁米诺－铁体系发光强度的增敏作用建立了水体中总铁的反向流动性化学发光检测方法。该法线性范围在１×１０＾－４－１０ｍｇ／Ｌ，检测限为３×１０＾－６ｍｇ／Ｌ，对于５×１０＾－３ｍｇ／Ｌ Ｆｅ测定９次的相对标准偏差为０．９％。此方法已用在水处理中总铁的监测。     

钇对Ti-1100高温钛合金热稳定性和蠕变行为的影响

量了Ｔｉ１１００和Ｔｉ１１００／０１％Ｙ（质量分数）高温钛合金在６００℃／１００ｈ空气中暴露后的拉伸性能及在６００℃／１５０ＭＰａ／１００ｈ条件下的蠕变性能，利用透射电镜观察了合金室温及蠕变后的组织。结果表明，Ｔｉ１１００合金加入０１％的Ｙ后，由于原始β晶粒得到细化，明显改善了其热稳定性；固溶在基体中的硅原子阻碍位错滑移和攀移，使蠕变中的回复过程难于实现；稀土还抑制α２相的长大，所形成的氧化物也阻碍位错的运动。这些均有利于提高Ｔｉ１１００合金的抗蠕变性能。