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Preliminary Study on Determining the Sequence of Intersecting Lines by Fluorescence Technique 下载免费PDF全文
Biao Li M.Sc. Guo liang Ouyang M.Sc. Peng nan Zhao M.Sc. 《Journal of forensic sciences》2018,63(2):577-582
The determination of the sequence of intersecting lines is an important part of questioned document examinations. A fluorescence technique was used to determine the sequence of heterogeneous intersecting lines produced using inkpad ink, stamp‐pad ink, ballpoint pens, gel pens, fountain pens, colorants of carbon paper, photocopiers, laser printers, and inkjet printers. A SteREO Discovery.V20 equipped with the ZEN Blue Lite software was chosen to perform the tests.As the results obtained from the study were positive under most conditions, the fluorescence technique was found to be very successful in determining the sequence of intersecting lines from ballpoint pen, gel pen, fountain pen, photocopier, laser and inkjet printers, and inkpad inks. The method was also successful in determining the sequence of intersecting lines from ballpoint pen, photocopier, laser printer, and stamp‐pad inks under most conditions. The technique was not successful in determining the order of crossing lines blending together. 相似文献
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利用激光刻章机雕刻、光敏印章机制印伪造印章印文是近年来出现的一种新的、仿真程度较高的伪造印章印文的方法。鉴定实践表明,这类伪造印章印文趋于专业化、技术化,且伪造的印章印文与真实印章印文的相似度较高。依据传统的鉴定依据和方法难以鉴别真伪,因此从该类伪造方法对其特点和鉴定依据、方法要点进行研究,尤其是对伪造形成方式及特点的研究,有助于科学的鉴定其真伪。 相似文献
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Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography-mass spectrometry (GC-MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed. 相似文献
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Identification of colorants in pigmented pen inks by laser desorption mass spectrometry 总被引:1,自引:0,他引:1
Pigments are rapidly replacing dyes as colorants in pen and printer inks, due to their superior colors and stability. Unfortunately, tools commonly used in questioned document examination for analyzing pen inks, such as TLC, cannot be used for the analysis of insoluble pigments on paper. Laser desorption mass spectrometry is demonstrated here as a tool for analyzing pigment-based pen inks. A pulsed nitrogen laser can be focused onto a pen stroke from a pigmented ink pen on paper, and positive and negative ions representative of the pigment can be generated for subsequent mass spectrometric analysis. Targeted pens for this work were a set of Uni-ball 207 pigmented ink pens containing blue, light blue, orange, green, violet, red, pink, and black inks. Copper phthalocyanine was identified as the pigment used to make both blue inks. A mixture of halogenated copper phthalocyanines were identified in the green ink. Unexpectedly, the pink ink was found to contain a red pigment, Pigment Red 12, treated with a mixture of water-soluble dyes. Each sample yielded ions representative of the pigments present. 相似文献
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A novel approach for the identification and dating of the fountain pen ink entries on paper has been established by ion-pairing high-performance liquid chromatography (IP-HPLC). Twelve black and six red fountain inks have been collected, and their ink entries have been prepared by drawing lines on paper. The chromatographic conditions for separation of their dye components after extraction with solvents were optimized. Under the optimized conditions, the 18 fountain pen inks were differentiated individually by comparing the number of detectable main or minor dye components, and the relative peak intensities of each component. The ink entries were artificially and naturally aged, and the analysis results showed that the ink dye components were significantly decomposed when exposed to UV or fluorescent light compare to those of inks stored under natural condition. The changes of the relative peak height for the dye components were linearly related to the aging time, especially under natural aging conditions. The degradation characteristics of the dye components under different aging conditions provide scientific evidences for dating of the suspicious fountain pen ink entries on document. 相似文献
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目的探讨利用积分光密度值判断印文形成时间的可行性,方法通过实验,利用Image-pro plus软件对不同时间段实验样本的印文积分光密度值数据进行采集、录入,并运用相关数据分析方法,对实验用三种品牌印油、印泥盖印印文的积分光密度值数据进行统计、分析。结果发现在1~120 d间数值下降速度较快,在120~380 d间数值减小幅度变缓,380 d后数值基本趋于稳定。结论随形成时间的延长印文的积分光密度值减小,一定时间后数值大小趋于稳定,在120 d内关联性较明显。 相似文献
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书写时间确定技术的国内现状与发展 总被引:2,自引:0,他引:2
综述了书写时间确定技术在国内的现状及最新发展,主要从三方面进行了介绍:水溶性书写时间确定技术;圆珠笔油墨书写时间确定技术;间接确定文件的书写时间方法。 相似文献