定量转印技术确定圆珠笔字迹的相对书写时间

定量转印技术是将单溶剂提取法与转印技术相结合形成的方法,实验表明该方法在一定条件下可以判定圆珠笔字迹的相对书写时间.     

Use of hand-held laser scanning in the assessment of craniometry

The intra- and inter-examiner reliability was evaluated for hand-held 3D laser scanning technology when it was combined with localization of landmarks for craniometry. The data from the laser surface scanning were compared with those of conventional direct measuring. Using thirty unidentified skulls requested for individual identification, measurements were taken of the line distances from lambda to 26 landmarks, and also for seven breadth parameters. For the laser surface scanning, two examiners performed replicate measurements with an interval of 1 week. In the conventional direct measuring, the first examiner took replicate measurements with a 1-week interval. To assess intra- and inter-examiner reliabilities, the intraclass correlation coefficient was used. Analysis of variance with repeated measures for each parameter was performed to compare the conventional method with the 3D scanning method. Both the 3D scanning and conventional methods showed excellent intra-examiner reliabilities, and the 3D laser scanning method also showed excellent inter-examiner reliability. A statistical difference between the two examiners was found only in nasal breadth in the 3D laser scanning method. There was no significant difference between the two measuring methods, though the 3D laser scanning method tended to give a slightly lower reading. Collectively, the 3D laser scanning method with point localization is a useful method with excellent reliability, and it can replace the conventional direct measuring method in craniometry.     

Differential infant mortality viewed from an evolutionary biological perspective

Evidence from family reconstitution studies suggests that variations in infant mortality may reflect differences in parental solicitude. For various proximate reasons that might originate from emotional, material or social interests, parents may be inclined to invest differently in the survival of their offspring. Evolutionary theory holds that the behavior-regulating mechanisms that cause differential parental care operate in a biologically functional manner. They obey the biological imperative of striving to propagate one's own genetic material in the gene pool of the population to the best possible degree, in view of prevailing socioecological constraints. From a Darwinian point of view, differential parental investment can be best understood as a socioecologically contingent tactical measure within an adaptive, i.e., genetic fitness enhancing strategy. Therefore, human reproductive decisions remain poorly understood unless their biological function in the Darwinian fitness competition is taken into consideration.     

Analysis and discrimination of electrical tapes: Part I. Adhesives

This study involved the comparative analysis and discrimination of 90 electrical tape adhesives. The objectives included the evaluation of the ability of individual techniques to discriminate samples and the assessment of the ability of the techniques combined to distinguish samples. The techniques utilized were stereomicroscopy, Fourier transform infrared spectroscopy (FTIR), pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS), and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). Stereomicroscopy, to assess adhesive colors of black, clear/colorless, and clear adhesives with brown tint, resulted in a discrimination of 53%. FTIR analysis yielded eight distinct groups with a discrimination of 67%. Py-GC/MS analysis resulted in 16 groups with a discrimination of 83%. These analyses confirmed and further subdivided the FTIR groups. SEM/EDS resulted in five separate groups at 17% discrimination, increasing the overall discrimination to above 85%.     

Differentiation of traumatic and heat-induced dental tissue fractures via SEM analysis

Previous studies have examined the effects of heating on teeth; however, none have identified characteristics that allow analysts to differentiate traumatic from heat-induced fractures. This study examined our ability to discern notable differences in preincineration traumatic fractures and heat-induced fractures in postincineration dentition. Twelve anterior dental specimens were subjected to blunt force trauma while a second set were not. All 24 samples were then incinerated in a muffle furnace at a peak temperature (900°C) consistent with house fires. The specimens were subsequently examined with a scanning electron microscope to identify and compare heat-induced and traumatic fractures. The results obtained during examination yielded no differences between the features displayed by specimens that had been inflicted with preincineration trauma and those that did not. Unlike bone, distinguishing features for the differentiation of traumatic and heat-induced fractures could not be compiled.     

Latent Fingerprint Visualization using a Scanning Kelvin Probe in Conjunction with Vacuum Metal Deposition

The application of vacuum metal deposition before scanning Kelvin probe visualization of fingerprints is investigated. The potential contrast between fingerprint ridges and furrows is maximized by the use of silver deposition for non‐noble metals and gold–zinc deposition for noble metals. The higher susceptibility of eccrine fingerprints to vacuum metal overdeposition is confirmed. Additionally, fingerprints are best developed individually and by building the metal deposition slowly to protect against overdevelopment and variation in the rate of metal condensation. The progress of the metal deposition can be monitored using the scanning Kelvin probe by reference to the change in potential and continuity of the new potential on the surface. The use of acetic acid solution for the recovery of overVMD‐developed samples is shown not to be useful. Applying the metal deposition has the additional prospect of increasing surface conductivity and homogeneity and both can aid fingerprint visualization using the scanning Kelvin probe.     

Identifying Diagonal Cutter Marks on Thin Wires Using 3D Imaging

We present work on matching 2‐mm‐thick wires using optical 3D imaging methods. Marks on such small surfaces are difficult to match using a comparison microscope as this 2D imaging method does not provide height data about the sample surface. Moreover, these 2D microscopy images may be affected by illumination. Hence, the reference and investigated sample should be present at the same time. We employed scanning white light interferometry and confocal microscopy to provide quantitative 3D profiles for reliable comparison of samples that are unavailable for simultaneous analysis. We show that 3D profiling offers a solution by allowing illumination‐independent sample comparison. We correctly identified 74 of 80 profiles using consecutive matching striae (CMS) criteria, and we were able to match samples based on profiles measured using different 3D imaging devices. The results suggest that the used methods allow matching cutter marks on thin wires, which has been difficult previously.     

Pyrotechnic reaction residue particle analysis

Pyrotechnic reaction residue particle (PRRP) production, sampling and analysis are all very similar to that for primer gunshot residue. In both cases, the preferred method of analysis uses scanning electron microscopy to locate suspect particles and then uses energy dispersive x-ray spectroscopy to characterize the particle's constituent chemical elements. There are relatively few times when standard micro-analytical chemistry performed on pyrotechnic residues may not provide sufficient information for forensic investigators. However, on those occasions, PRRP analysis provides a greatly improved ability to discriminate between materials of pyrotechnic origin and other unrelated substances also present. The greater specificity of PRRP analysis is the result of its analyzing a large number of individual micron-sized particles, rather than producing only a single integrated result such as produced using standard micro-analytical chemistry. For example, PRRP analyses are used to demonstrate its ability to successfully (1) discriminate between pyrotechnic residues and unrelated background contamination, (2) identify that two different pyrotechnic compositions had previously been exploded within the same device, and (3) establish the chronology of an incident involving two separate and closely occurring explosions.     

盐酸曲马多在大鼠体内的分布特点

目的观察盐酸曲马多在大鼠体内的分布及其特点。方法大鼠以3倍和6倍LD50228mg/kg剂量盐酸曲马多灌胃染毒致死,取材,薄层色谱法检测其心、肺、肝、脾、肾、大脑和血内盐酸曲马多的浓度。结果3倍LD50剂量组大鼠肾、肺、血、肝、大脑、脾和心组织盐酸曲马多的浓度分别为112±15、59±17、53±31、32±19.7、22±11.5、20±20、16.7±8.3μg/g或μg/ml;6倍LD50剂量组大鼠血、肺、肝、心、肾、大脑和脾中盐酸曲马多的浓度分别为107.6±7.2、26.3±20、11.7±6.6、11.2±7.2、10.3±3.6、6.38±0.2、6.1±0.3μg/g或μg/ml。结论3倍LD50剂量组大鼠,肾、肺、血内盐酸曲马多浓度最高;6倍LD50剂量组大鼠血、肺、肝中盐酸曲马多的浓度最高。盐酸曲马多中毒时,血、肝、肺和肾可以作为法医毒物分析的检材。     

A Study of the Presence of Gunshot Residue in Pittsburgh Police Stations using SEM/EDS and LC‐MS/MS

Due to possible secondary transfer of gunshot residue (GSR) onto a suspect in police custody prior to sampling, a baseline must be created for the amount of GSR present. With an increase of “lead free” ammunition, testing for both gunpowder and primer GSR is relevant. Seventy samples were collected using carbon‐coated adhesive stubs from four Pittsburgh Police Stations and vehicles to investigate these locations as sources of secondary GSR contamination. These seventy samples were analyzed for primer GSR using scanning electron microscopy‐energy‐dispersive X‐ray spectrometry. One primer GSR particle was detected; no sample was classified as positive for primer GSR. These same samples were then analyzed for gunpowder GSR using liquid chromatography coupled to tandem mass spectrometry to test for akardite II, ethylcentralite, diphenylamine, N‐nitrosodiphenylamine, 2‐nitrodiphenylamine, and 4‐nitrodiphenylamine. Ethylcentralite was quantifiable in two test samples. These results suggest there is a negligible potential for secondary transfer of primer and gunpowder GSR.