W(Ⅵ)-3,5二溴2,4-二羟基苯基荧光酮-CTMAB或CPB显色反应分光光度法测定地下水中六价钨

分光光度法是钨检测中最常用、简便的方法.钨的分光光度分析法的研究和应用在钨的化学分析中占主导地位,发表论文占总数的1/3以上.但多限于μg/mL 数量级检测,存在线性范围不宽、抗干扰不强的缺陷.文章主要讨论利用W(Ⅵ)-4,5二溴-(2,4-二羟基)苯基荧光酮-CTMAB或CPB显色反应体系进行对钨分光光度法进行改进.     

羧甲基-β-环糊精对氯化-1,4-二苄基-1,4-二氮杂双环[2.2.2]辛烷钨过氧化物的增溶作用

采用紫外分光光度法分析了羧甲基-β-环糊精对氯化-1,4-二苄基-1,4-二氮杂双环[2.2.2]辛烷钨过氧化物的增溶作用.分别考察了反应温度、反应时间和pH对溶解度的影响.实验结果表明,羧甲基-β-环糊精对氯化-1,4-二苄基-1,4-二氮杂双环[2.2.2]辛烷钨过氧化物的增溶效果显著,随着羧甲基-β-环糊精浓度的增大,氯化-1,4-二苄基-1,4-二氮杂双环[2.2.2]辛烷钨过氧化物在水中的溶解度也呈线性增大,而且当主体浓度增加7倍时,客体溶解度增加了12倍.30℃和pH 10的反应条件最有利于增溶.     

羧甲基-β-环糊精对氯化-1，4-二苄基-1，4-二氦杂双环[2．2．2]辛烷钨过氧化物的增溶作用

采用紫外分光光度法分析了羧甲基-β-环糊精对氯化-1,4-二苄基-1,4-二氮杂双环[2．2．2]辛烷钨过氧化物的增溶作用。分别考察了反应温度、反应时间和pH对溶解度的影响。实验结果表明,羧甲基-β-环糊精对氯化-1,4-二苄基-1,4-二氮杂双环[2．2．2]辛烷钨过氧化物的增溶效果显著,随着羧甲基-β-环糊精浓度的增大,氯化-1,4-二苄基-1,4-二氮杂双环[2．2．2]辛烷钨过氧化物在水中的溶解度也呈线性增大,而且当主体浓度增加7倍时,客体溶解度增加了12倍。30℃和pH10的反应条件最有利于增溶。     

ABTS分光光度法测定水中微量二溴海因中的有效溴

为检测水中低浓度二溴海因(DBDMH),基于有效溴与2,2'-连氮-双(3-乙基苯并噻唑-6-磺酸)(ABTS)在pH=2条件下产生绿色稳定存在的ABTS.+自由基的原理,使用ABTS显色分光光度法在405 nm测定二溴海因中的有效溴。该方法在0.08~1.61 mg/L有效溴范围内线性良好,最低检测限为0.02 mg/L。二溴海因水解产生的氨氮对测定影响很小。     

显色剂5-(5-碘-2-吡啶偶氮)-2,4-二氨基甲苯测定催化剂中的微量铂

研究了5-(5-碘-2-吡啶偶氮)-2,4-二氨基甲苯(5-I-PADAT)与贵金属铂(Ⅳ)的显色反应,建立了分光光度法测定铂的新方法。结果表明,在pH=5.5的HAc-NaAc缓冲溶液中,铂(Ⅳ)与试剂形成稳定络合物,络合物于3.5 mol·L^-1盐酸介质中可转变为另一种具有较高吸收特性络合物,最大吸收波长为595 nm,表观摩尔吸光系数为3.2×10⁴ L·(mol·cm)^-1。铂含量在（0～1.5） μg·mL^-1符合比尔定律。实验建立的分析方法快速,手续简便,选择性较好。     

2-(5-溴-2-吡啶偶氮)-5-二甲氨基苯胺分光光度法测定铜的研究

以2-(5-溴-2-吡啶偶氮)-5-二甲氨基苯胺(5-Br-PADMA)为显色剂,建立了分光光度法测定铜的新体系。实验结果表明,在p H=3.75~5.75的HAc-Na Ac缓冲溶液中,室温下铜与试剂形成配位比为1∶2的紫红色配合物,配合物最大吸收波长位于573 nm,表观摩尔吸光系数为5.89×104L·mol-1·cm-1。铜浓度在0~18μg/10 m L范围内符合比耳定律。所拟方法用于矿样中铜的测定,结果满意。     

2,3-二萘酚分光光度法测定水泥熟料中二氧化钛

分光光度法检测水泥熟料中二氧化钛含量,因仪器操作简单,备受分析工作者的青睐。目前,常用的方法有过氧化氢光度法和二氨替比啉甲烷光度法等,用其他显色剂测定二氧化钛的分光光度分析法也有不少研究。本实验研究了用2,3-二萘酚为显色剂分光光度法测定水泥熟料中二氧化钛。     

导管类医疗器械DEHP检测方法辨析

建立导管类医疗器械中邻苯二甲酸二(2-乙基)己基酯(DEHP)含量的检测方法。用紫外分光光度计与液相色谱仪分别对同一样品的DEHP含量进行检测。结果表明导管类医疗器械的DEHP含量检测,高效液相色谱法检测灵敏度和可信度上要优于紫外分光光度法。     

PTP1B抑制剂4,5-二-(2-溴-4,5-二羟基苯甲基)-1,2-二苯酚的合成及生物活性

以藜芦醛(Ⅰ)为起始原料,经过溴代、还原、傅克烷基化、脱甲基4步反应,合成了化合物4,5-二-(2-溴-4,5-二羟基苯甲基)-1,2-二苯酚(Ⅵ),总产率为53.5%。采用1HNMR、13CNMR、HREIMS等进行了结构表征。通过比色法对化合物Ⅵ及中间产物4,5-二-(2-溴-4,5-二甲氧基苯甲基)-1,2-二甲氧基苯(Ⅴ)进行蛋白酪氨酸磷酸酶1B(protein tyrosine phosphatase 1B,PTP1B)抑制活性测定,结果显示化合物质量浓度为20 mg/L时,化合物Ⅴ和Ⅵ的PTP1B酶抑制率分别为25.08%和79.48%,表明化合物Ⅵ具有较好的PTP1B酶抑制活性。     

紫外分光光度法测定2-氨基4,6-二羟基嘧啶的含量

采用紫外分光光度法在 2 6 1纳米波长下 ,测定 2 -氨基 - 4,6 -二羟基嘧啶的含量。该法简单、快速、准确 ,其标准偏差为 0 44 ,变异系数为 0 47% ,回收率为 97 47%～ 10 1 6 %     

WOx/ZrO2 catalysts: Part 3. Surface coverage as investigated by low temperature CO adsorption: FT-IR and volumetric studies

The adsorption of CO at 77 K on zirconia-supported tungsten oxide (ZW) samples prepared by equilibrium adsorption or by impregnation and with tungsten content up to 12.4 W atoms nm⁻² was studied with the aim of determining the coverage of ZrO₂ surface by the supported tungsten oxospecies. As an essential background for quantitative volumetric measurements, ZW samples were investigated by FT-IR spectroscopy to identify the surface sites responsible for the CO adsorption. FT-IR showed that CO adsorbed selectively and irreversibly on Zr_cus⁴⁺ centers of the support surface, but not on W_cus⁶⁺ sites. By volumetric determinations, the coverage of the zirconia surface by tungsten oxospecies was about 50% at maximum, irrespective of the preparation procedure and of the support crystallographic modification (monoclinic or tetragonal). Zirconia coverage remained significantly unchanged after leaching with a NH₃ solution that removed tungsten oxospecies not directly interacting with the zirconia surface. This finding indicates that ZrO₂ support coverage depends mainly on the tungsten species strongly anchored to the zirconia surface.     

The Effect of the Interface on the Impact Strength of Fiber-Reinforced Silicon Nitride Composites

Hot-pressed silicon nitride can offer large gains in gas turbine performance when used as a blade or vane provided the limitation of low impact strength can be overcome. Through the use of fiber reinforcement, energy absorption modes not available in monolithic materials are provided, with the result that the elevated temperature (1300°C) impact strength of an Si₃N₄ composite reinforced with 30 volume percent tungsten wires has been shown to increase ninefold over unreinforced Si₃N₄.To make use of the energy absorbing mechanisms of fiber pullout and/or interfacial splitting, one needs to retain the filament strength and have a fairly weak or low modulus interface or interfacial region between the tungsten and the silicon nitride. At elevated temperatures, this is the case; however, at room temperature the tungsten silicide layer formed at the W-S1₃N₄ interface during hot pressing has been found to render the tungsten reinforcement ineffective as a crack blunting constituent. Efforts are being made to prevent the formation of tungsten silicide through the use of interfacial barrier coatings and/or reducing the fabrication temperature.     

A flow model of porous anodic film growth on aluminium

The development of pores in a classical porous anodic film formed on aluminium in phosphoric acid solution is investigated. The study employs a tungsten tracer layer that is incorporated into the anodic film from the aluminium substrate, followed by detection of the tracer by transmission electron microscopy and Rutherford backscattering spectroscopy. Distortions of the tungsten layer on entry into the film and retention of tungsten species in the film are compatible with porosity arising mainly from flow of anodic oxide beneath the pore bases towards the cell walls. The behaviour is contrary to expectations of a dissolution model of pore formation.     

金属矿中钨钼铋检测方法研究综述

我国多金属矿中钨钼铋能否高效率的开发利用,提高其检测水平是至关重要的一部分。对金属矿中钨、钼及铋的检测方法进行了综述,为其检测提供有效参考。     

含氧酸根检测方法的研究现状及质谱法在钨钼分离中的应用前景

溶剂萃取法具有操作简单、回收率高、产品纯度高等优点，被广泛应用于钨钼分离。分离过程中钨钼离子形态会影响与萃取剂的结合方式及萃取历程，因而研究钨钼的离子形态变化有助于深入了解钨钼分离机理，进而指导工业生产。在水溶液中，钨钼的离子形态以钨钼含氧酸根形式存在，研究钨钼离子形态的本质即研究不同钨钼含氧酸根形式对萃取分离过程的影响。本工作综述了水溶液中含氧酸根离子形态的仪器分析方法，发现ESI-MS(电喷雾质谱法)在监测萃取过程中钨钼离子形态转化路径中具有潜在应用，并对ESI-MS在湿法冶金领域中监测钨钼离子形态及其转化规律的应用进行了展望，旨在为今后深入了解钨钼分离机理、定向调控钨钼分离过程及工业生产提供理论指导。     

Role of tungsten in supported Pt-W reforming catalysts Part II. Influence of the tungsten loading and metal-support interactions effect

Support Pt-W catalysts are studied for 3-methylhexane reforming. The increase in tungsten loading and the use of SiO₂ support instead of Al₂O₃ in Pt-W catalysts leads to the decrease in total activity and aromatization selectivity. X-ray Photoelectron Spectroscopy (XPS) has been applied to bimetallic Pt-W/Al₂O₃ and SiO₂ catalysts with different Pt/W ratios to try to explain the catalytic results. Observations lead to the conclusion that tungsten species are strongly anchored on the support in Pt-W/Al₂O₃ catalysts at low tungsten concentration. In this case, tungsten species are not reducible (oxidation state +VI) and not accessible catalytically; tungsten is hindered by small Pt particles. At large tungsten loadings, beyond the theoretical monolayer capacity of the support, a fraction of tungsten species migrates to the surface and becomes reducible. This fraction of tungsten-reducible species and large platinum particles are accessible on the surface, but another fraction of tungsten species strongly anchored on the support remains not accessible and not reducible. A model is proposed.     

生物样品中离子态和结合态镉分布的测定研究

以Ｎａｆｉｏｎ 化学修饰钨丝圆盘富集,石墨炉原子吸收光谱法测定生物样品中的镉。工作曲线线性范围为０．０５～０．４０ ｎｇ／ｍ Ｌ,检出限为０．０２ ｎｇ／ｍ Ｌ。以该法测定了尿样及血清中的离子态镉,直接进样石墨炉原子吸收光谱测定总镉后计算结合态镉,并分析了牛血清白蛋白和牛血红蛋白与镉的结合状况     

Preparation and characterization of tungsten tailing-based geopolymers

Using tailings to prepare constructive materials is of great significance for sustainable development of mineral processing industry. In this study, the possibility of preparing tungsten tailing-based geopolymers was explored in detail. XRD, FTIR, PLM, SEM and XPS analyses were carried out to characterize the phase composition, chemical bonding, microstructure, chemical state, and interface properties of tungsten tailing-based geopolymers. Results showed tungsten tailings presented little activity using NaOH as activator, while geopolymers with 60% non-pretreatment tungsten tailing and 40% metakaolin presented a 3-day compressive strength of 8.4 MPa and 28-day compressive strength of 9.1 MPa. The geopolymerization products of tungsten tailing-based geopolymers were N-A-S-H gels and aluminosilicate zeolite crystals, while tungsten tailings were wrapped by metakaolin-derived geopolymerization phases as aggregates with interfaces containing Si–O–Si bonding between quartz in tungsten tailings and zeolite and/or gel phase in metakaolin-derived geopolymer in the geopolymerization process. Besides, the leaching test results indicated that the immobilization efficiency of T6M4 geopolymers for Mn and Pb derived from tungsten tailings reached up to 97.28% and 99.95%, respectively. This research results provide a new idea for utilization of tungsten tailings on a large scale.     

Effect of the Cobalt Ion and Polyethyleneimine Adsorption on the Surface Forces between Tungsten Oxide and Cobalt Oxide in Aqueous Media

We used the colloidal probe technique with atomic force microscopy to study the interactions between a tungsten oxide sphere, WO₃, and flat oxidized tungsten and cobalt surfaces in aqueous electrolytes. We investigated the effects of adsorption of cobalt ions to tungsten oxide surfaces and adsorption of polyethyleneimine (PEI). Low concentrations of cobalt ions added to a WO₃ system resulted in extended hydration forces and a lowering of the absolute value of the surface potential. PEI was shown to adsorb to the WO₃ surfaces and induce an electrosteric repulsion in both the symmetric (WO₃–WO₃) and asymmetric (WO₃–CoOOH) systems. The possible complexation of cobalt ions with PEI does not significantly influence the thickness of the adsorbed layer.     

Investigation of Slow-Propagation Tungsten Delay Mixtures

The burning characteristics and reliability of slow-propagation tungsten delay mixtures (characteristic time 38–42 s/in) were studied experimentally by using various mixture compositions and tungsten particle sizes. Thermal analysis showed that potassium perchlorate is vital to initiate the reaction. Gravimetric analysis indicated that during the reaction overall mass loss of the delay mixtures did not exceed 5% compared to their initial mass. A mixture containing a tungsten powder of 6–8 μm was found to have the lowest effective activation energy, facilitating good ignition and burning zone propagation. The results of this study were successfully used to design a tiny delay which exhibited reliable ignition, burning and propagation characteristics under extreme conditions.