2-(5-溴-2吡啶偶氮)-5-二乙氨基酚显现人体皮肤表面镀锌工具遗留印迹

研究2-(5-溴-2吡啶偶氮)-5-二乙氨基酚(5-Br-PADAP)试剂显现镀锌工具遗留印迹的方法。 考察接触时间、时间间隔、试剂浓度、是否洗手等因素对印迹强度及分辨率的影响,并对该方法的可靠性进行验证。 实验结果表明,试剂浓度1 g/L、接触时间10 s以上,间隔时间不超过4 h条件下,均能显出较好的印迹。 该方法可以灵敏地显现镀锌工具遗留印迹,对非铁金属工具遗留印迹检测进行了很好地补充。     

基于金属有机骨架材料Tb-BTC显现潜指印的研究

为探究金属有机骨架材料在指印显现领域的应用,本研究采用预混合迅速滴显的方法,使金属有机骨架材料Tb-BTC直接络合在指印纹线上.使用该材料对渗透性客体中A4纸、黑色卡纸、牛皮纸;非渗透性客体中透明玻璃片、瓷砖上的皮脂指印进行显现,探究了不同配比、不同滴加顺序、不同显现时间的预混合溶液对不同类型、不同遗留时间、不同遗留物...     

铕掺杂SiO2复合凝胶在手印显现中的应用

采用溶胶-凝胶法合成了铕掺杂SiO2复合胶体材料,制备了可用于潜在汗液手印显现的磁性粉末(简称EMO),实验了该粉末显现刑事现场常见的渗透性和非渗透性客体表面潜在手印的效果,考察了手印遗留时间、显出手印荧光稳定性等因素对应用的影响,给出了复合凝胶的紫外可见吸收光谱和荧光光谱,解释了显现手印的基本原理.实验证明,该功能型材料可作为潜在汗液手印的良好显现粉末.     

金纳米粒子用于一步显现不同客体表面上的潜指纹

研究了在不加入任何保护剂的情况下, 将常温合成的金纳米溶液直接应用于指纹显现, 并研究了溶液pH值对指纹显现效果的影响. 金纳米粒子通过静电作用与质子化的指纹沉积物相结合, 选择性地沉积于指纹纹线的脊部, 从而实现潜指纹的显现. 实验结果证明, 该方法在较大的pH范围内(2.0～4.9)都能有效地显现非渗透性和半渗透性客体表面上的指纹, 在一定程度上能够显现出渗透性客体纸张上的潜指纹, 并且在pH＝3.0的条件下, 显现效果最好.     

铽荧光纳米配合物的制备及其潜血手印显现应用

以铽离子为发光中心、对苯二甲酸为第一配体、菲咯啉为第二配体,采用化学方法一步制备出表面羧基修饰的铽荧光纳米配合物。使用活化剂1-（3-二甲氨基丙基）-3-乙基碳二亚胺盐酸盐配合稳定剂N-羟基琥珀酰亚胺对配合物表面的羧基进行活化,促使活化羧基与潜血手印中的胺基在温和条件下迅速发生酰胺反应,成功实现了潜血手印的靶向显现。优化了潜血手印显现的最佳条件,显现悬浮液中配合物与水的质量比推荐为1：35,显现浸泡时间推荐为20 s。并深入探究了手印显现的对比度、灵敏度、选择性、适用性。实验结果表明,制备的表面活化羧基修饰的铽荧光纳米配合物适用于光滑非渗透性及半渗透性客体表面潜血手印的高质量与高效率显现。     

铽荧光纳米配合物的制备及其潜血手印显现应用

以铽离子为发光中心、对苯二甲酸为第一配体、菲咯啉为第二配体,采用化学方法一步制备出表面羧基修饰的铽荧光纳米配合物。使用活化剂1-(3-二甲氨基丙基)-3-乙基碳二亚胺盐酸盐配合稳定剂N-羟基琥珀酰亚胺对配合物表面的羧基进行活化,促使活化羧基与潜血手印中的胺基在温和条件下迅速发生酰胺反应,成功实现了潜血手印的靶向显现。优化了潜血手印显现的最佳条件,显现悬浮液中配合物与水的质量比推荐为1∶35,显现浸泡时间推荐为20 s。并深入探究了手印显现的对比度、灵敏度、选择性、适用性。实验结果表明,制备的表面活化羧基修饰的铽荧光纳米配合物适用于光滑非渗透性及半渗透性客体表面潜血手印的高质量与高效率显现。     

巯基丁二酸修饰的碲化镉量子点溶液显现不同客体表面潜指纹

利用具有宽且连续的荧光激发光谱和窄且对称的荧光发射光谱的水溶性巯基丁二酸修饰的碲化镉量子点溶液,成功显现了多种客体表面的潜指纹,且1～3s即可得到良好效果.该材料成功显现了水浸客体和粘连客体表面的潜指纹,而且在显现连续按捺产生的微弱指纹时展现出了优良的灵敏度.同龙胆紫、罗丹明6G和巯基乙酸修饰的CdTe量子点溶液相比,该溶液拥有更快的显现速度和更好的显现效果.     

DMAC优化试剂显现潜在手印研究

对二甲氨基肉桂醛(DMAC)是一种十分灵敏的潜在手印显现荧光试剂,本文在探讨其光学性能的基础上,通过大量样本实验考察了DMAC做为手印显现试剂时的最佳条件、灵敏度以及其在不同渗透性客体检材的应用效果。实验结果表明,浓度0.02g·L~(-1)的DMAC对普通纸张、热敏纸和报纸上的潜在手印显现可达到最佳效果,显出手印纹线清晰、连贯,即使是对存放1年的纸张检材,仍保持良好效果。     

神奇的“502”胶水——氰基丙烯酸酯胶黏剂在手印显现中的原理与应用

氰基丙烯酸酯20世纪70年代被引入法庭科学领域,成为显现非渗透性和半渗透性客体上潜在手印的高效方法。通过介绍氰基丙烯酸酯胶黏剂的发现与应用历史、聚合机理与手印显现原理、显出手印的增强方法,丰富了化学教育中关于聚合物、有机染料、荧光现象等方面的教学内容。     

5,6-二甲氧基-1,2-茚二酮的合成及其在潜在手印显现中的应用

以3,4-二甲氧基苯丙酸为原料,经3步反应合成了5,6-二甲氧基-1,2-茚二酮(4),总产率31%,其结构和性能经1HNMR,MS和FL表征。在510 nm波长激发下,4的最大发射峰位于563 nm。通过渗透性客体上的潜在手印显现实验考察了4的应用性能。结果表明:4具有较1,2-茚二酮更强的荧光效果。     

Adsorption of paraffin vapor on oxidized molybdenum substrates at nano- and micro-scales

Sputtered oxidized molybdenum surfaces were exposed at room temperature for different times to paraffin vapors obtained at 150 degrees C. Scanning polarization force microscopy (SPFM), optical and confocal microscopy were used to characterize the surfaces. The condensed morphologies are complex and strongly dependent upon the quantity of vapor molecules deposited on the substrate surface. A thin paraffin film is initially formed and quite uniform nano-height drops are nucleated randomly over it within 10-20 s time exposures. Their average contact angle ranged between 1 degrees -2.5 degrees . Further vapor deposition led to a more complex regime where nano-height drops do not show a clear interface with the film, while micro-sized drops do. The tangent approximation method adopted by Salmeron and Xu for the nano-drop regimes was extended to the micro-sized drop regime obtaining an averaged effective contact angle equal to 4 degrees -5 degrees . Both nano-height and micro-sized drops shape and effective contact angles have been discussed taking into account their interactions between the film and the drops.     

A new approach to separation and pre-concentration of some trace metals with co-precipitation method using a triazole

A new co-precipitation method was developed to separate and pre-concentrate Fe(3+), Cu(2+), Cr(3+), Zn(2+), and Pb(2+) ions using an organic co-precipitant, 3-benzyl-4-p-nitrobenzylidenamino-4,5-dihydro-1,2,4-triazole-5-on (BPNBAT) without adding any carrier element, following flame atomic absorption spectrometric (FAAS) determinations. Effect of some analytical conditions, such as pH of the solution, quantity of the co-precipitant, standing time, centrifugation rate and time, sample volume, and interference of concomitant ions were investigated over the recovery yields of the metal ions. The recoveries of the analyte ions were in the range of 95-102%. The detection limits, corresponding to three times the standard deviation of the blank, were found to be in the range of 0.3-2.0 microg L(-1). The precision of the method, evaluated as the relative standard deviation (R.S.D.) obtained after analyzing a series of 10 replicates, was between 1.6% and 6.0% for the trace metal ions. The method was validated by analyzing two certified reference materials and spiked addition. The proposed procedure was applied for the trace metal ions in some environmental samples.     

Study of sorption of Pb2+, Cd2+, Zn2+ and Cu2+ from wastewater on synthetic analogues of clintonite

The study describes a sorption of metal ions Pb²⁺, Cd²⁺, Zn²⁺ and Cu²⁺ on a synthetic mica clintonite. Synthesis of analogues of clintonite was carried out by using inorganic salts as sources of silicon and aluminum in the hydrothermal method. Alkaline conditions were applied to increase the nucleation rate. Powdered clintonite obtained after mechanical grinding was used for the removal of metal ions from the wastewater. The sorption experiments were done under batch process to measure the concentrations of metal ions. Effects of pH, contact time between sorbent and sorbate solution, amount of sorbent and temperature on the sorption of metal ions were studied. The sorption was shown to increase with the pH of the medium. The optimal conditions for sorption of metal ions on synthetic analogues of clintonite were determined.     

ZnCl＿2－尿素熔体的电化学研究

研究了温度、浓度对ＺｎＣｌ２－尿素熔体电导的影响,ＺｎＣｌ２－ＮａＣｌ－尿素熔体的电导率（１２５℃）可达３０ｍｓ·ｃｍ－１以上．用循环伏安曲线、恒电位电解及断电后的电位－时间曲线,研究尿素熔体中Ｚｎ２＋的电还原和锌在钛、铜电极上的电沉积．Ｚｎ２＋的电还原为一步可逆过程,锌沉积在铜电极上会形成ＣｕＺｎ５合金．Ｚｎ２＋在熔体中扩散系数为１．３×１０－６ｃｍ２·ｓ－１（１２５℃）     

Potassium ion-selective membrane electrodes based on 1,3-alternate calix[4]crown-5-azacrown-5

A series of 1,3-alternate calix[4]azacrown ethers for which the monoaza and unsymmetrical crowned-azacrown with different side arms were examined as an ionophore for ion-selective polymeric membrane electrode toward potassium ion. Among them, the electrode based on calix[4]crown-5-azacrown-5 with a phenyl group exhibited near Nernstian response for K⁺ ions over a wide concentration range (1×10⁻⁵ to 1×10⁻¹ M) with a limit of detection of 2×10⁻⁶ M. It has a fast response time of approximately 2-3 s and can be used for at least 2 months without observing any major deterioration. Selectivity coefficients indicated that interference from all common alkali, alkaline and transition metal ions was very small.     

Anodic Stripping Voltammetry of Heavy Metals at Nanocrystalline Boron‐Doped Diamond Electrode

Boron‐doped Diamond (BDD) electrode has become one of the important tools for heavy metal detection. By studying some analytical parameters of DPASV method, like deposition time and potential in different electrolyte concentrations (acetate buffer), the conditions for detecting very low metal ion levels (Zn, Cd, Pb, and Cu) could be chosen. Diluted electrolyte (0.01 M buffer) was one of the factors favoring low detection and quantification limits, but its quantification range is short in comparison to more concentrated media. For ?1.7 V deposition potential, the detection of single metal at ppb levels was reached in 60 s deposition time. Understanding different metal‐metal interactions shows the limits to the simultaneous determination of heavy metals at BDD. Quantification was possible for the simultaneous determination of Zn, Cd and Pb despite the overlapping of Zn and Cd peaks. The performance of the BDD was compared with that of another C‐based solid electrode: the glassy carbon electrode (without mercury plating). A lower base line current, wider potential range, higher sensitivity (3 to 5 times higher than GC) and longevity of the material were noticed for the BDD.     

Wettability of carbon nanofiber layers on nickel foils

Carbon nanofiber (CNF) layers have been directly synthesized on nickel foils by chemical vapor deposition at 450°C using different H(2) concentrations and reaction times. The addition of 5% H(2) produces thicker, rougher and more porous CNF layers than when 1% H(2) is used. The roughness and porosity increases with reaction time when 5%, 10% or 20% H(2) are used; however, this effect is less pronounced when 1% H(2) is used. CNFs are 50-55 nm in diameter and have a fishbone type structure. We have studied the influence of CNF layer thickness, porosity and surface roughness on the interaction with water by measuring the contact angle. The water wetting properties of the samples are more significantly influenced by the CNF layer thickness than both surface roughness and porosity. When the CNF layer is thicker than ca. 20 μm, the surface is hydrophobic and the contact angle increases with surface roughness and porosity. When the CNF layer is thinner than ca. 20 μm, the surface is hydrophilic and the contact angle decreases with increasing surface roughness and porosity. This behavior is attributed to penetration of water, making contact with the hydrophilic C layer between the CNF layer and the foil.     

Atomic absorption spectrometric determination of trace amounts of copper and zinc after simultaneous solid-phase extraction and preconcentration onto modified natrolite zeolite.

This work assesses the use of modified natural natrolite zeolite as an adsorptive material for the separation and preconcentration of trace amounts of ions. In this work we investigated the potential of modified natural natrolite zeolite for the simultaneous separation and preconcentration of trace amounts of copper and zinc ions. We have developed a simple, rapid, selective, sensitive and economical method for the simultaneous separation and preconcentration of trace amounts of copper and zinc in an aqueous medium using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) as an analytical reagent. The sorption was quantitative in the pH range 7.5 - 9.5, whereas quantitative desorption occurred instantaneously with 5.0 mL of 2 mol L(-1) nitric acid. Linearity was maintained between 0.05 - 6.0 microg mL(-1) for copper and 0.02 - 1.5 microg mL(-1) for zinc in the final solution. Ten replicate determinations of 1.0 microg mL(-1) copper and 0.5 microg mL(-1) zinc in a mixture gave mean absorbances of 0.1687 and 0.2788 with relative standard deviations of +/-1.2% and +/-1.3%, respectively. The detection limits were 0.03 ng mL(-1) for Cu(II) and 0.006 ng mL(-1) for Zn(II) in the original solution (3 sigma(bl)/m). Different parameters, such as the effect of the pH, flow rate, breakthrough volume and interference of a large number of anions and cations, were studied and the proposed method was used for the determination of these metal ions in water as well as standard samples (e.g. Nippon Keikinzoku Kogyo (NKK) CRM, No. 916 and No. 920 aluminum alloy, National Institute for Environment Studies (NIES) No. 1 pepperbush and NIES No. 2 pond sediment). The determination of these metal ions in standard samples showed that the proposed method has good accuracy (recovery > 97%).     

Lead Ion‐Selective Polypyrrole Solid‐Contact Electrode Based on Crown Ether

Abstract

The lead(II) ion selective solid‐contact electrode based on polypyrrole film, covered with a polyvinyl chloride membrane has been prepared. Polypyrrole film was used as a mediating layer of the solid‐contact electrode due to the conductivity. Crown ether has been used as ionophores in polyvinyl chloride cocktail solutions. This solid‐contact electrode based on benzo‐15‐crown‐5 exhibited Nernstian‐response within 30 s response time over concentration range, 1×10^?1～5×10^?7 M. The selectivity of this electrode to other metal cations was comparatively good. This electrode showed much better results, such as detection range, slope, response time and reproducibility than conventional ion selective electrode and coated wire electrode.