5F-UR-144的热不稳定性研究

目的利用气相色谱-质谱法(GC-MS)、液相色谱-四级杆-飞行时间质谱(LC-Q-TOF/MS)和核磁共振光谱法(NMR)研究合成大麻素5F-UR-144遇热分解的具体变化情况。方法对照品用无水乙醇定容稀释后,经GC-MS和LC-Q-TOF/MS检测得到对应的色谱图和质谱图;对照品分别于常温和280℃密封加热后用无水乙醇定容稀释,经LC-Q-TOF/MS和NMR检测得到对应的质谱图、¹H和¹³C核磁共振波谱;对照品分别于常温逐步提升至300℃密封加热后用无水乙醇定容稀释,经LC-Q-TOF/MS检测得到对应的色谱图。结果5F-UR-144在高温下会开环产生新的物质;5F-UR-144从130℃开始分解,随着温度升高分解程度提升,240℃时分解率达到98%;随着温度继续升高,超过260℃,分解产物会碳化。结论基于5F-UR-144的热不稳定性,在检测时应考虑若通过烫食方式吸食5F-UR-144,其进入人体的成分会发生变化;气相色谱或气相色谱-质谱法不适合定量检测5F-UR-144。     

Forensic Imaging‐Guided Recovery of Nuclear DNA from the Spinal Cord*,†

Abstract: Our objective is to document the recovery of DNA from the spinal cord or surrounding dura mater in 11 cases of severely burned human remains. Radiographs established that portions of charred tissue contained spine segments. Multidetector computed tomography (MDCT) revealed that each spine specimen contained an intact spinal cord remnant. A full DNA profile was obtained from seven specimens using spinal cord dura mater in six specimens and spinal cord medulla in one specimen. A partial profile was obtained from four specimens (spinal cord dura mater, 2; spinal cord medulla, 2). Bone and muscle surrounding the spinal cord appear to insulate nucleic acid containing tissue from critical thermal degradation. The spinal cord, which is easily identified by MDCT examination of remains and easily recovered at the postmortem examination, can be a source of DNA with extraction yields comparable with other tissue sources. Specimens of dura mater are preferable as processing time is faster than bone.     

针刺干预无先兆偏头痛患者的弥散张量成像研究

目的 通过弥散张量成像（diffusion tensor imaging,DTI）技术和纤维束自动定量分析（automated fiber quantification,AFQ）方法探讨无先兆偏头痛患者在针刺干预前后脑白质纤维的变化。方法 纳入无先兆偏头痛患者20例和健康受试者10例,无先兆偏头痛患者进行每周3次、连续4周的针刺干预,干预前后分别进行DTI和T1像扫描,健康受试者不针刺,仅进行1次核磁扫描。比较无先兆偏头痛患者针刺前后以及无先兆偏头痛患者和健康受试者基于AFQ方法的各向异性分数（fractional anisotropy,FA）值。结果 与健康受试者比较,无先兆偏头痛患者右皮质脊髓束、右上纵束部分节点FA值显著减弱（P＜0.05）;与针刺前比较,无先兆偏头痛患者头痛天数及头痛程度显著下降（P＜0.05）,头痛频率下降不显著,无先兆偏头痛患者右皮质脊髓束、右上纵束、左扣带回部分节点FA值显著增强（P＜0.05）。结论 无先兆偏头痛患者存在广泛白质纤维束受损,针刺能促进受损的脑白质纤维恢复。     

磁敏感加权成像在出血性弥散性轴索损伤鉴定中的应用

目的探讨磁敏感加权成像(susceptibility weighted imaging,SWI)在出血性弥散性轴索损伤(diffuse axonal injury,DAI)法医学鉴定中的应用价值。方法对20例DAI的法医学鉴定资料进行回顾性分析,对其T1WI、T2WI、扩散加权成像(diffusion weighted imaging,DWI)、液体衰减反转恢复(fluid attenuated inversion recovery,FLAIR)、磁敏感加权成像(susceptibility weighted imaging,SWI)序列影像资料进行统计分析。结果 DAI出血灶多位于脑组织表浅区,SWI对出血性DAI的检出率最高,与其他序列成像之间的差异有统计学意义(P0.05)。结论 SWI在DAI法医学鉴定中具有重要的意义。     

THEMIS紫外光谱成像仪的放大率估计及其图像的长宽比校正

目的 校正THEMIS紫外光谱成像仪图像的长宽比并估计系统放大率参数.方法 制作测试图片,用紫外光谱成像仪拍摄紫外光谱影像集,由图像和测试图片的差异分析出成像缺陷和放大率参数.结果 通过Photoshop测量像素值的方法测量出图像的长宽比差异,并用MATLAB算法校正,同时得出紫外光谱成像仪的放大倍率β.结论 校正后紫外光谱图像恢复了原始比例,且系统放大率β可以在恢复痕迹原始大小时发挥作用,由此获得准确的紫外光谱图像供后续光谱分析检验和研究.     

Evaluation of Four Fingerprint Development Methods for Touch Chemistry Using Matrix‐Assisted Laser Desorption Ionization/Time‐of‐Flight Mass Spectrometry,

Four preparation techniques for MALDI/TOF mass spectrometry were compared to determine the ability to gather intelligence for investigations through the chemical analysis of latent fingerprints, defined as “touch chemistry.” Compatible fingerprint development processes used for identification along with new techniques are necessary to evaluate touch chemistry. Ten volunteers deposited fingerprints from solvent residues containing drugs and explosives onto microscope slides. The developers included (A) fingerprint powder, (B) MALDI matrix, (C) fingerprint powder and lifting, and (D) cyanoacrylate fuming with fingerprint powder. Qualitative identification was based on ion images and spectra. The highest average detection rates (88%) were found using methods A and B. Methods C (52%) or D (18%) had limited success. Results demonstrate the importance of imaging coupled to extracted mass spectral data in detecting analytes in deposited fingerprints. Overall, the results suggest continued development of touch chemistry applications could prove useful for gathering intelligence and forensically relevant information.     

磁性纳米复合材料在法医学领域中的应用展望

磁性纳米复合材料用于生物分离具有许多优势,在法医领域具有广阔的应用前景,本文就其技术特点和在生物分离上的应用进行简要综述。     

Visualization of latent fingerprints using fluorescence lifetime imaging on paper emitting strong fluorescence

Latent fingerprints were successfully visualized using fluorescence lifetime imaging (FLIM) on paper which emits strong fluorescence with a lifetime close to that of fingerprints and thus from which it is difficult for time-resolved spectroscopy to visualize fingerprints. Latent fingerprint samples on paper were excited using a 450 nm or 532 nm nanosecond pulsed-laser, and time-resolved fluorescence images were obtained at a delay time of 6–16 ns in intervals of 1 ns, to the excitation pulse. The excitation beam was expanded using a lens, and the fluorescence from the fingerprints was captured using an intensified CCD camera. Because of the large fluorescence intensity of the background paper of approximately two to four orders of magnitude larger than that of the fingerprint, the fingerprint was not visualized on each fluorescence image by time-resolved spectroscopy. However, the fingerprint was visualized in a FLIM image constructed using a series of the fluorescence images for the case with the fluorescence intensity of the background paper being four orders of magnitude larger than that of the fingerprint. The difference in fluorescence lifetime in the FLIM image of the visualized fingerprint and background paper was in the order of 0.1 ns, which was an order of magnitude smaller than the inherent fluorescence lifetime of a few nanoseconds for the fingerprints and paper. It was demonstrated that, at a background fluorescence intensity with a certain order of magnitude larger than that of fingerprints, FLIM has the potential to visualize latent fingerprints which cannot be visualized by time-resolved spectroscopy.     

Infrared Imaging of the Crime Scene: Possibilities and Pitfalls

All objects radiate infrared energy invisible to the human eye, which can be imaged by infrared cameras, visualizing differences in temperature and/or emissivity of objects. Infrared imaging is an emerging technique for forensic investigators. The rapid, nondestructive, and noncontact features of infrared imaging indicate its suitability for many forensic applications, ranging from the estimation of time of death to the detection of blood stains on dark backgrounds. This paper provides an overview of the principles and instrumentation involved in infrared imaging. Difficulties concerning the image interpretation due to different radiation sources and different emissivity values within a scene are addressed. Finally, reported forensic applications are reviewed and supported by practical illustrations. When introduced in forensic casework, infrared imaging can help investigators to detect, to visualize, and to identify useful evidence nondestructively.     

American Atrocity Revisited: National Identity,Cascading Frames,and the My Lai Massacre

This study draws on the “cascading activation” model of press-state relations to explore U.S. political and news discourse surrounding the 1968 My Lai Massacre. We systematically analyze White House, military, congressional, and news communications and draw upon scholarship in social psychology to assess why the press might challenge certain frames in response to My Lai but indiscriminately echo others. In particular, within these communications, we examine how serious and widespread the actions at My Lai were conveyed to be, how the circumstances were portrayed, how the actors involved in the incident were characterized, and the extent to which America’s core values were questioned. Our findings suggest that the Nixon administration employed frames designed to downplay the severity of the My Lai incident, highlight extenuating circumstances faced by those directly involved, denigrate the alleged low-level perpetrators, and bolster the national identity. These frames were then largely echoed in the press, despite consistent and forceful challenges by congressional Democrats. These findings, we argue, align with the cascading activation model, and we build on it by highlighting the underlying importance of “cultural resonance” in the framing process. We reflect on the theoretical and practical implications of these patterns and, in doing so, engage the broader scholarly debate over the process through which U.S. news coverage aligns with the communications of government officials, particularly in moments of national dissonance.