二氧化钒多级纳米结构材料显现潜指纹研究

本文旨在建立使用VO₂多级纳米结构材料显现潜指纹的方法。以氧化二乙酰丙酮合钒和过氧化氢水溶液为原料，通过溶剂热法一步合成VO₂多级纳米结构材料，利用X射线衍射(XRD)和场发射扫描电子显微镜(FESEM)对合成粉体进行表征。最后采用撒粉刷显法对不同客体上的汗潜指纹、油潜指纹进行显现，并与传统粉末的显现效果进行对比。结果表明，合成的VO₂为深蓝色粉体，纯度高，形貌均匀，为纳米棒组成的亚微米球多级结构；该粉体可以与指纹遗留物质相结合，具有较高的灵敏度，显现的指纹纹型清晰，纹线连贯，对比度高，细节特征显著。与传统粉末相比，VO₂多级纳米结构材料在载玻片和透明塑料杯上潜指纹的显现效果要好于金粉、银粉和磁性粉；在铝箔上VO₂的显现效果好于金粉和银粉。VO₂多级纳米结构材料合成方法简单、成本低，制备的VO₂纯度高、无杂相；潜指纹显现实验证明该粉体可有效显现非渗透和渗透性客体上的汗潜、油潜指纹，并且在载玻片、透明塑料杯和铝箔上潜指纹的显现效果优于传...     

JLGW-I-1指纹显现膜显现热敏纸上潜在手印

指纹是刑事案件中最常见也是最有价值的物证之一。有效地发现和提取犯罪分子遗留在现场的指纹,是正确识别和鉴定指纹的必要条件之一。目前已有许多先进技术应用于指纹显现。对纸张上的潜在指纹最有效的方法是利用茚三酮和DFO溶液,但受热敏纸自身性质的限制,利用这两种物质进行显现时会导致基质颜色改变,无法达到对潜在指纹进行显现的目的。本文介绍一种新型指纹显现基质可有效解决这一问题。现将有关实验情况报告如下。1实验材料和方法(1)JLGW I1指纹显现膜(吉林省公安厅物证鉴定中心研制);热敏纸(市售)。(2)取市售热敏纸,由志愿者捺印…     

简易条件下运用数码相机翻拍指纹

在刑事案件现场遗留的指纹中 ,有一种为自然光下可见指纹 ,如加层指纹、减层指纹 ;另一类为自然光下不可见指纹。如何将自然光下不可见指纹变为清晰可见并成功提取始终是刑事技术工作的研究课题。一般情况下 ,采用粉末刷显方法来显现指纹是常规手段。然而不同条件下粉末刷显指纹的效果并不一样。笔者发现 ,秋季至冬天供暖之前采用粉末刷显指纹显现效果最佳。为了找到其中的道理 ,笔者用相同实验材料在不同温度 (不同时间 )条件下进行了实验 ,结果发现相同温度下的指纹显现效果并不一样 ,而不同温度下的指纹显现效果有些却完全相同。由此得出…     

基于聚集机理显现潜指纹发光材料的研究进展

由于潜指纹具有独一无二、终生不变的特点,且包含了人体丰富的化学信息(如内源性物质、外源性物质),故常被称之为个体“信息银行”。指纹的检测已不仅在法医鉴定、个体识别方面起着重要作用,同时还广泛的应用于日常生活中的安全检验和访问控制等领域。尽管DNA分析对个体识别方面,得到了极大的发展,但对潜指纹的显现和分析,仍然是公安技术人员获得个人可靠信息的主要来源。在过去的几十年里,研究人员朝着无损、快速、简易和高效的实现对潜指纹显现的目标出发,开发了许多新的技术和新的材料,也在一定程度上解决了传统潜指纹显现材料对人体伤害较大(如粉尘污染、光学伤害等)的问题,但潜指纹显现在灵敏度及无损检测方面仍然面临着较大的挑战。通过对近年来指纹显现材料与潜指纹的相关成分在溶液中通过疏水-疏水作用、静电作用或抗体-抗原相互作用等,在指纹的嵴上聚集后显现潜指纹的角度出发,对该类潜指纹显现材料的设计和研究进展进行了系统性综述。     

利用CdSe巯基乙酸溶液显现水浸客体表面潜手印

目的研究水浸客体表面潜指纹的显现方法;方法利用CdSe巯基乙酸溶液显现被水浸泡过的黄色封箱胶带、黑色塑料袋、玻璃等常见非渗透性客体上的潜手印,讨论影响水浸非渗透性客体上潜手印显现效果的各种因素,并与传统方法进行比较,初步探讨了CdSe巯基乙酸溶液显现水浸非渗透性客体表面潜手印的方法;结果使用巯基乙酸包覆CdSe纳米复合材料显现潜在手印,使每分子纳米复合材料外表包覆足够数量的羧基,则可以提高它同手印残留物的结合能力,从而得到更高清晰度、更高分辨率的手印显像;结论巯基乙酸包覆CdSe纳米复合材料可以很好的显现水浸塑料、胶带等表面潜指纹。     

三种β-取代茚三酮的合成及显现汗潜手印的研究

本文基于傅克酰基化取代反应合成了三种茚三酮类似物：β-甲氧基茚三酮、β-硝基茚三酮、β-甲基茚三酮,比较并研究相同配方下三种β-取代茚三酮在不同纸张上显现汗潜手印的效果,并分别与茚三酮进行比较,分析其优劣。结果显示,三种β-取代茚三酮的显现液基本可显示不同纸张上的新鲜指纹,但β-硝基茚三酮对于陈旧指纹的显现效果较差,且显现液本身为棕褐色,显示出的指纹纹线为黑褐色,故视觉感官上稍劣于其他两者;β-甲氧基茚三酮和β-甲基茚三酮的效果均与茚三酮相当,灵敏度略高于茚三酮,显色后的稳定性高于茚三酮。研究表明,β-位取代基的变化能够改变茚三酮类化合物显现手印的效果,给电子基团的修饰能够提高该类化合物的手印显现性能,化合物本身的荧光性能与实际的指纹显现效果并不直接相关。     

低温荧光法显现汗潜指纹初探

目的　探索汗潜指纹显现的新方法。方法　利用低温荧光摄影方法加强指纹沉积物的固有荧光强度 ,来提高汗潜指纹显现的成功率。结果　在 4 1 5nm波段激发下用黄滤色镜拍摄指纹的显现效果最好。结论　低温荧光法是一种有效的潜指纹显现的技术手段     

提取球面体上指纹的简易方法

在勘查犯罪现场时,往往发现犯罪分子遗留在球面体(如灯泡、圆球形门把手)上的指纹,用一般的粉末显现,胶带提取,很难将指纹完整地提取下来,拍照则易产生变形。本人通过实验,发现用市售的聚乙烯醇合成胶水可简便地将指纹提取下来。 1 原理 聚乙烯醇合成胶水是一种浓稠状的透明粘合剂,将其滴在光滑物体表面,扩散后干燥可形成透明的薄膜,因其是种粘合剂,在干燥后可将附着于光滑物体表面的物质粘附住。所以用其提取     

对植物叶面上汗潜手印显现方法的探讨

1996年,在某地发生一起作案者挖洞进入仓库盗窃物品的案件,笔者在勘查现场时,发现几片半新的玉兰树叶,经分析认为可能是作案者利用它们来使其指纹不留在地面上,故认定树叶上可能留有作案者的指纹。对树叶进行指纹显现:首先,用常规的植物花粉撒粉吹显法进行显现,取得了一定的效果(见图1)。笔者对剩下的树叶利用金粉来进行显现,亦取得了较好的效果(见图2)。为此,笔者对树叶上汗潜手印的显现作了进一步的探讨、实验。     

纸张上薄膜拓印指纹检验研究

目的研究薄膜拓印指纹的特征和检验方法。方法利用塑料薄膜在纸张上进行了120次指纹拓印实验,然后比较拓印指纹和正常捺印指纹。结果成功转印出较清晰的拓印指纹41枚,发现了纸张上拓印指纹的常见特征。结论通过特征分析可以对薄膜拓印指纹进行检验。     

Firearms discharge residue sample collection techniques.

Critical comparisons of Ba and Sb in firearms discharge residue were made on samples collected by three independent collection technqiues. Collection materials studied were transparent adhesive tape, (Scotch Brand), a solution of cellulose acetate in acetone ("Film Lift"), and plastic-shafted cotton swabs wetted with dilute nitric acid. Flameless atomic absorption analyses were performed with a Jarrell-Ash Model 810 instrument equipped with a tantalum strip atomizer. Tape and cotton swabs gave comparable positive indications of residue, with frequencies of 90 and 80%, respectively. The plastic Film Lift gave fewer positives, with a frequency of 50%. With the transparent tape lift, gunshot residue particles are discernible, making nondestructive microscopic identification possible prior to destructive elemental analysis.     

透明材料上的透明附着物证检测

目的提出了一种检测透明材料上附着透明物证的新方法—位相滤波法。方法采用现代光学信息处理技术改变光信号的频谱,使零级频谱与一级频谱干涉。结果实现了由位相到强度的调制,最终检测到透明材料上的透明附着物证。结论该方法是一种无损光学检测法,操作简便,效果好。     

The analysis of forensic samples using laser micro-pyrolysis gas chromatography mass spectrometry

Laser micropyrolysis gas chromatography-mass spectrometry is used for the analysis of paint, photocopier toner, and synthetic fiber materials to test the forensic potential of this emerging technology. It uses a laser microprobe to selectively target very small parts of the materials for GC-MS analysis. Whereas the paint and the toner samples were amenable to direct laser pyrolysis, the synthetic fibers proved transparent to the 1064 nm laser radiation. The difficulty with the fibers demonstrates that a specific laser wavelength may not be appropriate for all types of materials. Nevertheless, the fibers were able to be indirectly pyrolyzed by impregnation in a strongly absorbing graphite matrix. A vast array of hydrocarbon pyrolysates was detected from the different materials studied. Unique product distributions were detected from each sample and in sufficient detail to facilitate individual molecular characterization (i.e., molecular fingerprinting). The integrity of the laser data were confirmed by comparison to data obtained from the same samples by the more conventional pyroprobe pyrolysis GC-MS method. The high spatial resolution and selectivity of the laser method may be advantageous for specific forensic applications, however, further work may be required to improve the reproducibility of the data.     

A method for collection of gunshot residues from skin and other surfaces

A method of collecting gunshot residues from the skin of persons who have been injured by firearms has been developed. The method uses a commercially available, adhesive, transparent plastic film. This method is also useful for collecting gunshot residues from other objects, such as leather. The shooting distance is later estimated by ocular, microscopic or IR examination in combination with various chemographic tests.     

Bloodstain pattern analysis & Bayes: A case report

The findings from a bloodstain pattern analysis (BPA) may assist in formulating or falsifying scenarios that are considered in the investigative stages of a criminal investigation. When a case proceeds to trial the bloodstain pattern expert may be asked about the relevance of their findings given scenarios that are proposed by the prosecution and defense counsel. Such opinions provided by an expert are highly relevant to police investigation or legal proceedings, but the reasoning behind the opinion or implicit assumptions made by the expert may not be transparent.A proper framework for the evaluation of forensic findings has been developed since the late twentieth century, based on the hierarchy of propositions, Bayesian reasoning and a model for case assessment and interpretation. This framework, when implemented in casework, mitigates some of the risks of cognitive biases, and makes the reasoning and scientific basis for the opinion transparent. This framework is broadly used across forensic science disciplines. In this paper we describe its application to the field of BPA using a case example from the Netherlands Forensic Institute (NFI).     

Identification of pressure-sensitive adhesive polypropylene tape

Identification of colorless, transparent, pressure-sensitive adhesive polypropylene tape (PP tape) was performed using infrared absorption spectrometry (IR) and pyrolysis gas chromatography mass spectrometry (Py-GC/MS) to determine the pressure-sensitive adhesive. Twenty different products of colorless, transparent PP tapes were examined in this study, and the results of analysis of IR spectra and Py-GC/MS were classified into twelve groups. In addition, the tapes were classified into 14 groups on the basis of IR measurement of release agent present in the backside. The results indicate that colorless, transparent PP tapes can be distinguished in terms of manufacturer, thereby demonstrating that this method of identifying colorless, transparent PP tape is effective. Moreover, the method was applied to the analysis of an actual forensic sample.     

塑料制品上锉除文字的显现研究及原理讨论

目的研究塑料制品上损毁文字的加热显现方法,探讨显现原理;方法将盗窃案涉及的常见塑料客体上的凸面文字进行锉除,对文字消除部位进行加热显现;结果清晰显现了几种常见塑料客体上的消除字迹;结论在利用加热法显现塑料客体上消除的文字时,塑料表面损毁程度、客体材质、生产工艺等因素对显现结果产生重要影响。     

真空镀膜中膜系选择对潜手印显现的影响

目的探究在真空镀膜中不同镀膜材料能否显现出潜手印并比较不同镀膜金属显现手印的效果。方法使用不同的镀膜金属显现多种类型客体表面的潜手印。结果存在可替换镀膜材料。结论可替换镀膜金属对潜手印显现的效果良好,纹线清晰连贯,背景反差大,并对特定客体上的手印显现极具优势。     

To be continued . . . Syntheses and trends in follow-up of quality assurance in West European higher education

The authors report on West European trends in follow-up arrangements of national quality assurance procedures. They argue that external quality assurance ought to adopt a broader conception of quality than is now often the case. Next, the general public ought to have a guarantee that external quality assurance is valid (through meta-evaluation) and has consequences (through follow-up arrangements). Follow-up currently is not well developed in many European countries in a formal sense, but is receiving more attention as external quality assurance is maturing. Finally, the authors link national quality assurance to the European dimension; an international network could fulfil important functions in making quality assurance transparent and credible across Europe. This revised version was published online in August 2006 with corrections to the Cover Date.     

Can financial development enhance transparency?

A substantial strand of literature unambiguously established the importance of financial development for economic growth. Relatively less attention has been paid to the impact that financial development of a country can have on important development outcomes like transparency. As established by existing research, strong financial institutions in a country would imply an improved and transparent banking system, better corporate governance, ease of accessing credit, greater availability of information and best practices in investment protection. All these should theoretically promise a more transparent economic system. Our empirical findings confirm this. Using several estimation strategies, our results confirm that greater financial development enhances transparency.