打印复印文件朱墨时序表观特征初探

本文详细介绍了一案例的检验过程,并通过简单实验对激光打印、静电复印形成文件的朱墨时序的表观特征进行了粗浅的探究。总体而言,两种时序在朱墨交叉点的表观特征上具有文字与印文均完整、肉眼感觉文字均压在印文之上的共同点;在两者本质的差异点上,先朱后墨表现为交叉点的墨粉与未交叉部位一致,先墨后朱表现为交叉点的墨粉光泽度增加、具有潮湿感、以及易出现水珠状的印油积聚现象。     

激光显微捕获口腔上皮细胞的DNA分型

目的探索激光显微技术(lasercapturemicrodissectionsystem,LCM)捕获口腔上皮细胞,并进行STR-DNA分型检测的方法。方法用VERITAS显微切割仪红外低能激光显微捕获一定数量口腔上皮细胞,进行ProfilerPlus试剂盒STR复合扩增,检测DNA基因型。结果7～8个口腔上皮细胞能成功获得STR-DNA分型。3～4个口腔上皮细胞不能成功获得STR-DNA分型。结论激光显微捕获作为一种分离单个细胞的新技术,对于微量口腔上皮细胞的STR-DNA分型是可行的。     

胚兔牙囊发育生物行为的组织形态学观察

研究胚兔的牙囊发育生物行为与人的牙囊发育是否相似 ,为人口腔疾病的研究提供模拟实验动物模型 ,采用光镜、电镜及激光扫描共聚焦显微镜对 4 3只胚兔的牙囊发育过程进行形态学观察。结果显示 ,牙囊来源于外胚间质 ,通过胚胎诱导形成牙支持组织 ,分化产生成牙骨质细胞、成骨细胞、成纤维细胞 ,形成牙骨质、固有牙槽骨、牙周韧带及其基质 ,对牙齿发育阶段具有保护和稳定作用 ,调控未来形成的牙周结构 ,在早期发育阶段首先出现 ,与人牙囊发育基本相似 ;最终牙囊在牙冠的顶部形成索引带 ,诱导继承牙萌出 ,在牙冠的根部形成牙支持组织 ,一部分牙囊细胞有程序性细胞死亡 ,以维持牙囊发育期内环境的生理平衡     

Detection of Mitragynine in Mitragyna Speciosa (Kratom) Using Surface-Enhanced Raman Spectroscopy with Handheld Devices

A simple, quick, selective, sensitive, and effective field-friendly method capable of being used by nonexperts has been developed for detecting mitragynine in Mitragyna speciosa (kratom) using surface-enhanced Raman spectroscopy (SERS). Over 100 samples and blanks (known to be either positive or negative for the presence of mitragynine) were examined in duplicate using five identical handheld Raman spectrometers, which provided a data set of over 1,000 examinations. Based on the results of these analyses, the method yielded a true-positive rate of 99.3%, a true-negative rate of 97.9%, a false-positive rate of 2.1%, and a false-negative rate of 0.7%. The average minimum detectable concentration (C_m) of mitragynine that reproducibly yielded a match for one of the library spectra on all five instruments was determined to be 342 ng/mL (ppb). This C_m value is a conservative estimate considering that the extraction process was not fully optimized by this study, which was not necessary since the C_m value achieved was well below typical mitragynine concentrations in kratom (1.3–2.3%). The method is ideal (i) for prioritizing samples for additional testing using other more time-consuming laboratory-based techniques needed to detect and quantify mitragynine and (ii) for field use at international mail facility (IMF) satellite laboratories to help interdict kratom and prevent this dangerous product from reaching the U.S. supply chain.     

Determining Line-Crossing Sequences Between Laser Printing and Writing Pen Using Coaxial Light

Determining the application sequence of hand-written pen ink and printer toner lines has attracted significant interest in questioned document examination. This study uses coaxial light to determine line-crossing sequences, with intersections observed under a VSC600 forensic document workstation and a Leica M205A Stereo-microscope. Results show that reflected light at intersections and color contrast between intersections and nonintersections was observed when a hand-written ink line passes over a toner line, while a toner line passing over a written line appeared dull, with no color contrast. The procedure was tested under a range of conditions, such as types of writing pens and laser printers, the writer, and writing pressure, with the latter playing an important role in the evaluation. To validate the results, a 90% detection rate and 98% accuracy rate were achieved from 50 samples of blind testing, which is more effective than optical microscopy.     

Evaluation of Suspected Counterfeit Pharmaceutical Tablets Declared to Contain Controlled Substances Using Handheld Raman Spectrometers

This study describes the performance of handheld Raman devices for determining whether suspect pharmaceutical tablets declared to contain controlled substances were consistent with authentic (CWA) or not consistent with authentic (NCWA) tablets using a simple, rapid, field-friendly method capable of being used by nonexperts. Twenty-five authentic products and 84 known NCWA tablets were examined using three “parent” devices for a total of 327 analyses. On average, the parent devices yielded a true pass rate of 100%, a true fail rate of 98.4%, a false pass rate of 1.6%, and a false fail rate of 0%. The methods/libraries were then transferred to 13 identical “daughter” devices, which were used to examine 10 suspect finished dosage forms in duplicate (six known NCWA tablets and four authentic tablets) for a total of 260 measurements. On average, the daughter devices had a true pass rate of 100%, a true fail rate of 95.5%, a false pass rate of 4.5%, and a false fail rate of 0.0%. These data demonstrate that the parent–daughter electronic transfer method was successful, which permits the ability to develop methods in the laboratory that can be seamlessly pushed out to field devices. The methods can then be used to (i) prioritize samples for additional testing using other more time-consuming laboratory-based techniques needed to detect and quantify active ingredients and (ii) help support the interdiction of dangerous tablets at ports of entry, thereby preventing them from reaching the supply chain.     

“同版“印章的实验研究

制作了13枚"同版"渗透型印章和激光雕刻印章,分析了这些"同版"印章的印面特征和盖印印文特征.研究发现,相同条件下制作的"同版"印章的个体差异十分微小,如果考虑到各种盖印条件下,这些印章盖印印文特征的变化范围,"同版"印章印文的检验是十分困难的,甚至是不可能的.     

激光传真文书检验初探

利用传真文书进行犯罪以及由传真件引发的经济纠纷逐年上升。目前文书检验领域对新型激光记录传真文书的研究涉及较少，有必要通过对激光传真机的工作原理、记录方式、传真件及其传真文字特点的研究来说明现阶段激光传真文书的检验。     

In Situ Identification of Semen Stains on Common Substrates via Raman Spectroscopy,,

The spectroscopic identification of body fluids in situ is a major objective in forensic science. This approach offers the confirmatory, nondestructive, rapid, and on‐scene identification of various body fluids. Although Raman spectroscopy has shown tremendous promise toward this goal in prior proof‐of‐concept experiments, a significant challenge which still remains is substrate interference. Here, an approach for detecting semen stains in situ on various substrates using Raman spectroscopy is explored. Simulated semen evidence was prepared on skin, glass, and various fabrics. Raman data were accumulated from stains without any pretreatment using a common confocal mapping spectrometer using 785 nm laser excitation. The results demonstrate that the spectroscopic interferences encountered by substrates can be reduced and eliminated using a combination of existing subtraction techniques and chemometric models. Heterogeneous substrates proved most challenging, however, automatic subtraction treatment, and location of fluid hotspots was able to elucidate a clear spectroscopic signature of semen in every instance.     

Incestuous paternity detected by STR-typing of chorionic villi isolated from archival formalin-fixed paraffin-embedded abortion material using laser microdissection

Microscopic examination of a blood clot expelled by a physically and mentally disabled woman taken to the emergency room because of genital bleeding revealed the presence of chorionic villi encircled by decidua, hemorrhage, and necrosis. In order to identify the father of the product of conception, sections of formalin-fixed, paraffin-embedded abortion material were subjected to laser microdissection: DNA extraction from chorionic villi selectively isolated from the surrounding tissues allowed successful STR-typing of fetal cells, which was otherwise prevented by excess maternal DNA. The large number of homozygous genotypes in the fetal profile suggested incestuous paternity. Analysis of reference DNA samples from male relatives excluded the woman's father, paternal grandfather, and maternal grandfather, whereas the obligate paternal alleles of the fetus were constantly present in the genotypes of the woman's brother, clearly demonstrating brother-sister incest (probability of paternity > 99.99999%).