Collecting touch DNA from glass surfaces using different sampling solutions and volumes: Immediate and storage effects on genetic STR analysis

Touch DNA has become increasingly important evidence in todays' forensic casework. However, due to its invisible nature and typically minute amounts of DNA, the collection of biological material from touched objects remains a particular challenge that underscores the importance of the best collection methods for maximum recovery efficiency. So far, swabs moistened with water are often utilized in forensic crime scene investigations for touch DNA sampling, even though an aqueous solution provokes osmosis, endangering the cell's integrity. The aim of the research presented here was to systematically determine whether DNA recovery from touched glass items can be significantly increased by varying swabbing solutions and volumes compared with water-moistened swabs and dry swabbing. A second objective was to investigate the possible effects of storage of swab solutions prior to genetic analysis on DNA yield and profile quality when stored for 3 and 12 months, as is often the case with crime scene samples. Overall, the results indicate that adapting volumes of the sampling solutions had no significant effect on DNA yield, while the detergent-based solutions performed better than water and dry removal, with the SDS reagent yielding statistically significant results. Further, stored samples showed an increase in degradation indices for all solutions tested, but no deterioration in DNA content and profile quality, allowing for unrestricted processing of touch DNA samples stored for at least 12 months. One further finding was a strong intraindividual change in DNA amounts observed over the 23 deposition days which may be related to the donor's menstrual cycle.     

玻璃雨飞溅高度及分布的实验研究

目的研究平板玻璃打碎后玻璃雨的飞溅高度及空间分布,从而为玻璃物证提取和现场分析提供依据。方法应用自制的实验装置,模拟嫌疑人手持硬物击碎窗户玻璃,收集窗户下地面上和打击者处飞溅的玻璃微粒,对颗粒大小、散布区域进行统计分析,并与通过动力学计算得出的分布进行比较。结果在距离窗户0.5m处,玻璃颗粒的飞溅高度可高于玻璃上相应来源点的高度;较小颗粒有较大的飞溅范围。结论玻璃雨颗粒大小分布和空间分布规律对于嫌疑人身上、头部玻璃物证的提取以及案件的现场分析有十分重要的意义。     

An investigation into the spatial elemental distribution within a pane of glass by time of flight secondary ion mass spectrometry

Advances in the technology employed for the manufacture of glass have resulted in a final glass product with little variability in terms of its physical and optical properties. For example, the refractive index of Australian float glass tends to lie between 1.5189 and 1.5194. It has therefore become necessary to complement physical and optical methods for forensic glass comparison with instrumental elemental analyses. In a previous study, time-of-flight secondary ion mass spectrometry has been shown to offer potential for the analysis of glass particles as small as a few tens of microns across. In this study, the three-dimensional homogeneity of a sheet of float glass is described, and consequences for forensic elemental analysis of glass particles of such size are explored. Variation in Si, Ca, Mg, and Na levels immediately under the nonfloat surface was observed, with the variance accompanied by a decrease in refractive index.     

毛细管气相色谱柱的保养与维护

综述了毛细管气相色谱柱的保养与维护.就毛细管柱分析使用中常遇到的一些问题,例如如何避免色谱柱的断裂,固定相的损伤,色谱柱的污染以及如何解决一些不能避免的问题和应采取的措施、步骤.     

混和硅油测定玻璃折射率

目的建立混合硅油测定单纯用B油和C油无法测定的玻璃折射率的方法。方法将B油和C油分别按1:2和2:3的体积比配成两种混合硅油,用此两种混合硅油测定同一块玻璃的折射率。结果用此两种硅油测得的玻璃的折射率结果无显著性差异。该方法克服了玻璃折射率仪温度范围窄(25℃～125℃)的缺点。     

Laminated safety glass as an intermediate target: a wound ballistic study

Various 9‐mm ammunitions (A1, A4, A5, ST, GS, GSb, P.E.P., SeCa, HP, PTP/s, VM, McVG, DM41, PTP, SX2, PT, and MEN frangible) were tested regarding their velocity, energy, angle of impact, and potential wound channel after penetrating a car window at 30° and 90°. Test materials were gelatine, soap, and pig cadavers. The velocities of the projectiles were between c. 288 and 430 m/ses, the energy spread between 394 and 564 J. Handgun bullets fired through vehicular side window glass lose substantial energy reducing the effectiveness of the ammunition. This effect is greater when fired at an angle of 30° compared to 90°. At a shooting angle of 90°, none of the different projectiles showed remarkable differences considering its wound ballistic features. Accuracy is maintained at a 90° angle but seriously impaired at 30°. None of the examined ammunition complied with the demanded wound channel effectiveness of 30–60 J/cm.     

油浸法测定玻璃折射率的不确定度评定

目的建立油浸法测定玻璃折射率不确定度的评定方法。方法按照不确定度的A类和B类评定方法,对未知玻璃折射率测定过程中不确定度分量进行计算,最终确定扩展部不确定度。结果油浸法测定玻璃折射率的扩展不确定度约为4×10-5。结论根据不确定度计算出来的折射率的变化范围与实际分析中折射率的变化范围完全吻合。     

Profiles of Academic Activities and Careers: Does Gender Matter? An Analysis Based on French Life Scientist CVs

The aim of this paper is to analyze the factors that influence the length of time to promotion for male and female academics. Promotion is defined as elevation to a professorship. We examine the role of academic profiles, which are based not only on publications, but also include activities such as fund raising, consulting, teaching, and managerial appointments (dean of a department for instance). The paper examines the factors that speed up or slow down the progress of an academic career for males and females, respectively, to explore the “glass ceiling” effects. Survival and duration models are used to test whether the gender differential persists after controlling for observed and unobserved heterogeneity. The originality of this paper lies in the use of duration models to track sex differences in promotion criteria. It highlights that the different criteria of promotion for male and female academics: women have to demonstrate higher involvement in different networks in order to be promoted.     

根据爆炸现场玻璃的破碎推算炸药量的研究

本文通过对爆炸现场玻璃破碎处冲击波峰值超压的研究,得出推算炸药量的三个计算公式,并通过实际案例的验算,对推算炸药量公式的适用范围进行了分析讨论.