Ultraviolet illumination as an adjunctive aid in dental inspection

Tooth-colored resin fillings have become increasingly popular as restorative materials. Their presence in the dentition presents a challenge to the clinician and the forensic odontologist, as detection of the fillings can be difficult both visually and radiographically. As they necessarily form part of the unique dentition of an individual, recognition of the resins is important for forensic identification. Alternative light sources have been used with success in various fields of forensic science. In recent years small LED flashlights emitting at specific wavelengths in the ultraviolet light (UV) range have been developed. Their low cost, small size, and ready availability makes their use practical in both forensic dental inspection and clinical settings. UV inspection is of interest because enamel, dentin and dental materials all have differing fluorescent properties when illuminated by UV light. It was one goal of this research to quantitatively assess the fluorescence properties of modern restorative resins in order to predict their behavior during inspection using UV illumination. The second goal was to demonstrate practical use of UV in dental inspection with examples of how different materials fluoresce. Quantitative measurements were obtained for optical emission wavelength and intensity for 15 modern resins using a spectrophotometer. Results indicated that resin brands fluoresce at different wavelengths and with varying intensities. Practical use and comparison of the flashlights revealed that the most useful excitation wavelengths for resin detection were in the UVA range (365 and 380 nm). Porcelain restorations and composite resin fillings exhibited different responses to these two wavelengths and thus use of both is recommended for forensic dental inspection.     

An examination of the sequence of intersecting lines using attenuated total reflectance-Fourier transform infrared spectral imaging

In this study, the potential of attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectral imaging as a technique to determine the sequence of line crossings was examined. The technique was successful in determining the sequence of heterogeneous line intersections produced using ballpoint pens and laser printers. By imaging at characteristic frequencies, it was possible to form spectral images showing the spatial distribution of the materials. By examining the spectral images from the inks, it was possible to determine whether the ink was above or below the toner. In blind testing, ATR-FTIR spectral imaging results were directly compared to those obtained by eight experienced forensic document examiners using methods regularly employed in casework. ATR-FTIR spectral imaging was shown to achieve a 100% success rate in the blind tests, whereas some incorrect sequence determinations were made by the forensic document examiners when using traditional techniques. The technique was unable to image ink-jet printing, gel pens, roller ball pens, and felt-tip pens, and was also unable to determine the sequence of intersecting ballpoint pen lines.     

In search of blood--detection of minute particles using spectroscopic methods

An examination protocol for rapid detection of remnants of blood particles on garments of suspects in bloody murder cases is described. Microparticles of blood are sampled along with fibres and hairs using the tape lifting method. The tapings are searched with a low power microscope for red particles with morphology similar to blood. Presumed blood traces are further examined using microspectrophotometry on the cut out piece of taping. The typical visible spectrum of haemoglobin is characteristic for blood. Alternatively Raman spectroscopy can be used to measure the characteristic vibrational spectrum of haemoglobin. At a later stage, these particles may be removed from the piece of taping in order to extract the blood and attempt to obtain a genetic profile.     

用傅立叶变换红外光谱法检验激光打印机墨粉

采用傅立叶变换红外光谱法对8个厂家的16种型号的激光打印机墨粉进行检测。研究结果表明,根据红外吸收光谱图中在特征频率范围内吸收的差异可以将这16种型号的墨粉分为五大类,根据指纹区吸收峰的差异可以对同一类别中的不同墨粉进行进一步的区分鉴别。该研究对激光打印机形成的文件检验具有现实意义。     

In situ Study on the Diffusion Kinetics of Seal Ink by Microinfrared Spectroscopy

In document examination, it is of great importance to determine the composition of seal ink with different imprint times, and spectroscopic methods are widely used today. In this research, the diffusion of seal inks from three different brands on the same type of paper is monitored in situ by microinfrared spectroscopy and microinfrared imaging technology. The area of the absorption peak at 1743 cm^?1 gradually decreases with increasing diffusion time. The diffusion kinetics of seal ink on paper are also studied by analyzing the infrared spectra of seal inks at the same measuring point with different diffusion times. The research provides a basic study in understanding the diffusion behavior of seal ink on paper over short time spans.     

Experimental Research on Class Identification with a New Type of Erasable Gel Pens

A new type of erasable gel pen ink is becoming increasingly popular because of the modifiable characteristics for writing on documents. This study attempts to distinguish 12 types of blue and black erasable gel pens produced by mainstream stationery manufacturers using infrared (IR) visual analysis, Fourier transform infrared (FTIR) analysis, fluorescence analysis, and microspectrophotometry. The results demonstrate that IR visual, FTIR, and fluorescence analysis can be used to help distinguish each type of erasable gel ink. While microspectrophotometry can be used to effectively differentiate the blue gel inks in this study, there are limitations with respect to distinguishing black erasable gel pens. When these four optical analyses methods were used in combination, the gel inks could be accurately distinguished.     

1H‐NMR with Multivariate Analysis for Automobile Lubricant Comparison

Identification of suspected automobile‐related lubricants could provide valuable information in forensic cases. We examined that automobile lubricants might exhibit the chemometric characteristics to their individual usages. To compare the degree of clustering in the plots, we co‐plotted general industrial oils that were highly dissimilar with automobile lubricants in additive compositions. ¹H‐NMR spectroscopy was used with multivariate statistics as a tool for grouping, clustering, and identification of automobile lubricants in laboratory conditions. We analyzed automobile lubricants including automobile engine oils, automobile transmission oils, automobile gear oils, and motorcycle oils. In contrast to the general industrial oils, automobile lubricants showed relatively high tendencies of clustering to their usages. Our pilot study demonstrated that the comparison of known and questioned samples to their usages might be possible in forensic fields.     

表面增强拉曼光谱快速检测食品基质中毒物

目的建立常见食品基质中氰化物等五种毒物的拉曼光谱快速分析方法。方法采用水、乙腈及乙酸乙酯作为提取剂对饮用水、苹果以及烤鸭三种常见食品基质中氰化物、百草枯、毒死蜱、甲拌磷以及敌鼠钠五种毒物进行提取,并使用表面增强拉曼光谱法检测。结果实验表明,每种毒物均有其独特的拉曼信号,这些特征信号可作为其定性的判别依据,氰化物在饮用水、苹果以及烤鸭这三种基质中的检出限均不大于1μg/mL(g);百草枯的检出限在0.05~0.1μg/mL(g)之间;毒死蜱、甲拌磷的检出限在0.05~1μg/mL(g)之间;敌鼠钠检出限在0.1~1μg/mL(g)之间,均满足现场检测需求。结论该方法操作简单且分析速度快,为毒物的快速筛查提供了较好的解决方案。     

Characterisation and discrimination of so-called metallised fibres found in clothing and decorative materials originating from the consumer market

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Field-portable detection of fentanyl and its analogs: A review

The need to detect fentanyl and its analogs in the field is an important capability to help prevent unintentional exposure or overdose on these substances, which may result in death. Many portable methods historically used in the field by first responders and other field users to detect and identify other chemical substances, such as hazardous materials, have been applied to the detection and identification of these synthetic opioids. This paper describes field portable spectroscopic methods used for the detection and identification of fentanyl and its analogs. The methods described are automated colorimetric tests including lateral flow assays; vibrational spectroscopy (mid-infrared and Raman); gas chromatography–mass spectrometry; ion mobility spectrometry, and high-pressure mass spectrometry. In each case the background and key details of these technologies are outlined, followed by a discussion of the application of the technology in the field. Attention is paid to the analysis of complex mixtures and limits of detection, including the required spectral databases and algorithms used to interrogate these types of samples. There is also an emphasis on providing actionable information to the (likely) non-scientist operators of these instruments in the field.