Changes in Attenuated Total Reflection Fourier Transform Infrared Spectra as Blood Dries Out

The time since deposition (TSD) of a bloodstain is a valuable piece of evidence for forensic scientists to determine the time at which a crime took place. The objective of this study was to determine whether attenuated total reflection (ATR) Fourier transform infrared (FTIR) spectroscopy could be used to estimate the TSD of a bloodstain in a relatively early period (from 0 min to the time required for the bloodstain to dry out). For this purpose, we used ATR‐FTIR to study the variation in absorbance at certain wavelengths as rat and human blood sample dried out. The absorbance at 3308/cm (A3308) was found to have a close correlation with the TSD during this time period, and the changes in A3308 during the drying of rat and human blood drops under the same controlled conditions showed similar results. The current study indicates that ATR‐FTIR spectroscopy has potential as a tool for estimating TSD at early time periods of blood deposition.     

Fabrication of compound nonwoven materials for soft body armor

The primary objective of body armor research is the development of low-cost, lightweight, wearable garments that effectively resist ballistic impact. This study introduces a material intended to reduce nonpenetration trauma by absorbing energy from ballistic impacts. Layers of web were made by low-melting point polyester (LMPET) on unaligned fibers of high-strength polyamide 6 (HSPA6). A compound nonwoven fabric was made by laying high-strength Vectran filaments between two layers of HSPA6-LMPET web. The new fabric underwent needle punching and thermal bonding to form a composite sandwich structure. The new fabric was subjected to a falling weight impact test and a ballistic impact test. The results indicated that the material with the new design reduced maximum indentation depth by 8%. Furthermore, soft body armor made from the material with the new design would cost less to produce and would weigh 22.5% less than conventional soft body armor.     

Visualizing latent fingerprints on color-printed papers using ultraviolet fluorescence

Laser detection of latent fingerprints on a white paper has been performed, previously. Ultraviolet fluorescence from various kinds of printer toner and ink used for home printers were measured to study fluorescence imaging of fingerprints on a color-printed white paper. The experimental system consisted of a nanosecond pulsed tunable laser and a cooled CCD camera. Excitation wavelengths are 230 and 280 nm. Fourteen printers consisting of three color laser printers, three color inkjet printers, five monochrome laser printers, two monochrome copy machines, and a color copy machine were tested. Toner and ink of most printers exhibited fluorescence in the region from 360 to 550 nm. In most cases, clear fluorescence images were obtained by time-resolved imaging with a band-pass filter and 280-nm excitation. However for toners from laser color printers that showed strong fluorescence, better results were obtained with 230-nm excitation. Latent fingerprints on a photograph page and a black-character page of a newspaper were also imaged.     

论应对气候变化背景下能源开发利用与环境保护相结合原则

能源开发利用产生的环境问题日益严重,直接威胁到人民的生活质量和发展,能源开发利用与环境保护相结合原则是指在开发利用能源时,必须减少污染排放,加强环境保护,它也称清洁开发利用能源原则。在应对气候变化背景下,能源立法的基本原则应该树立低碳能源和低碳经济理念,坚持能源开发利用与环境保护相结合原则。     

拉曼光谱成像技术检验朱文时序时印文油墨种类对检验结果的影响

目的考察在运用拉曼光谱阵列面扫描检验朱文时序的方法中印文油墨种类对检验结果的影响。方法根据拉曼谱图的不同对搜集的21种印泥印油进行扫描并分类,采用拉曼光谱阵列面扫描技术对印泥印油与同一书写笔形成的朱文时序样本进行检验。结果 21种印泥印油被分为11类,21种印泥印油与蓝色签字笔形成的朱文时序样本都得到了良好的检验结果。结论印文油墨种类用拉曼光谱阵列面扫描检验朱文时序的检验结果没有影响。     

能源变革中的首都西南区域经济发展与战略选择

石油、天然气等非再生能源供给约束对经济发展的制约,使人类开始探索第三次能源变革。伴随每次能源结构变革是现代产业发展的巨大变化,后者又进一步推动经济社会发展。北京致力于世界城市建设,其经济社会发展要形成国际影响力与控制力,其顺应能源发展趋势的合理产业布局至关重要,而首都西南区域目前正处于传统产业退出、接续产业尚未形成时期,如果利用后发优势,建立国家战略性新兴能源产业基地,将可能实现区域经济的跨越式发展。     

基于能耗的碳排放研究

粗放式经济的发展导致高强度的碳排放,面对全球气候变化的严峻形势,低碳经济给出了一条可持续的发展之路。我国是一个人口大国,经济发展规模较大加上经济结构不合理,导致能耗高、碳排放强度大,为了减少碳排放,应对气候变暖的危机,我们必须走低碳经济之路,国家要开征碳税,引导合理的能源消费,由粗放型经济向集约型的低碳经济转变,调整产业结构,优化能源消费结构,提高能源的最终利用效率,从而达到经济效益和环境效益的＂双赢＂。     

Gunshot residue in Chicago police vehicles and facilities: an empirical study

Suspects in shooting investigations in Chicago are routinely transported in department vehicles and detained in department facilities prior to gunshot residue (GSR) evidence collection. The GSR test results are used to associate the suspect with primary exposure to GSR. The potential for these vehicles and facilities being sources of secondary GSR contamination needed to be determined. A total of 201 samples were collected from randomly selected vehicles and detention facilities. The sampling collected trace materials from surfaces that suspects' hands may contact during the arrest process. These samples were examined for the presence of GSR particles using scanning electron microscopy. Upon completion of the automated analysis, those particles that met an initial GSR screening criterion were relocated and reanalyzed. The locations where GSR particles were recovered allowed us to make recommendations to the Chicago Police Department with regard to transporting and detaining these suspects. The low number of GSR particles recovered suggests that the potential for secondary contamination, although present, is relatively low.     

Quick Screening of Crystal Methamphetamine/Methyl Sulfone Exhibits by Raman Spectroscopy

Abstract: The analysis of mixtures of “crystal meth” (usually comprised of methyl sulfone [MS] and methamphetamine [MA]) by gas chromatography‐mass spectrometry (GCMS) is routine in many forensic drug laboratories. The utilization of Raman spectroscopy for the identification of such mixtures quickly and without the need for a separation technique is discussed. Samples were dissolved in water and Raman spectra of the resulting aqueous solutions were collected. By comparing these spectra to spectra of methylsulfone and MA mixtures of known composition, an indication of the composition of the sample can be obtained in only a few minutes. This spectral comparison also can be used as a semi‐quantitative analysis of MA concentrations in such exhibits.     

Optical Characterization of Some Modern “Eco‐Friendly” Fibers*

Abstract: Fibers that are termed “eco‐friendly” or “biodegradable” by manufacturers are increasingly being used in textile products such as apparel and carpeting to appeal to the ever more environmentally aware public. As such, these modern fibers are expected to begin showing up more often in forensic casework, and it is important that the forensic examiner recognize them. This study employed polarized light microscopy (PLM) and Fourier transform infrared (FTIR) microspectroscopy to characterize selected fibers of azlon, polylactic acid (PLA), cellulose composites of alginate or chitin, and bamboo (viscose rayon). Fiber cross‐sections, refractive indices, melting points, solubilities, and FTIR measurements were conducted. Results indicate that the azlons and PLA fibers are easily distinguishable from other textile fibers by their optical and chemical properties. The cellulose composites show only small differences in comparison with other cellulose‐based fibers, while bamboo viscose rayon is indistinguishable from normal viscose rayon.