纸张物证的分析检验方法

纸张是犯罪现场经常出现的物证。对纸张物证的分析检验在案件侦破中有着重要作用,因此,法庭科学工作者一直对纸张物证的检验方法进行深入研究。随着法庭科学实验室的发展,纸张的检验技术得到了长足的进步,由传统的单一仪器分析方法发展到现在多种分析技术的联合应用,从而建立了快速、有效、灵敏的检验方法,为涉及纸张物证的案件侦破做出了显著的贡献。本文对纸张物证的分析检验方法进行了介绍和讨论。     

三维光学断层技术在活体成像中的应用

三维光学断层成像(Three Dimensional Optical Tomography Imaging)是以光学探针标记的分子或细胞为成像源,在外部光源的激发下产生发射光,通过测量组织边界处的光强,结合光子在组织中的传播模型,来重建出组织内部发射光分布图像以及组织光学参数。三维光学断层成像能够提供目标物在生物体内的分布信息,克服平面成像的局限性。因此,在肿瘤检测、基因表达、蛋白质分子检测、揭示机体功能变化等方面有着很大的应用潜力。本文总结了光学相干断层成像(Optical Coherence Tomography,OCT)、荧光分子断层成像(Fluorescent Molecular Tomography,FMT)、生物自发光断层成像(Bioluminescence Tomography,BLT)、切伦科夫荧光断层成像(Cerenkov Luminescence Tomography,CLT)等三维光学断层活体成像技术的新进展,分析了其在实际应用中所面临的技术挑战并探讨了相应的解决方案。     

质谱新技术在物证分析中的应用

物证分析对于案件侦破及法庭诉讼均具有重要作用.新兴质谱技术因其直接、快速、灵敏和无损等特点在物证分析中得到广泛应用.本文综述了国内外几种新兴质谱技术在检测爆炸物、违禁药物、潜指纹及真伪文件笔迹等物证中的应用研究实例,并展望了质谱新技术在物证分析方面的发展前景.     

解析电喷雾电离质谱成像技术在口红类化妆品物证检验中的应用北大核心CSCD

目前法庭科学物证检验中对化妆品类物证的研究较少,检测手段多以色谱检测为主,样品前处理过程复杂,且难以进行准确定性.据此,以口红类化妆品为例,提出了适合口红成分分析的解析电喷雾电离质谱成像检测方法,并用于检测30种不同品牌口红样品,根据正、负离子模式下得到的准分子离子及碎片离子质荷比,对比不同档次口红成分和质谱数据的差异,初步建立适用于刑事技术的口红质谱信息数据库.该方法重复性好、定性能力强,无需复杂的样品前处理即可对口红中的主要成分进行快速定性检测,一方面可应用于口红产品的真伪鉴别,另一方面可对实际案件中口红残留物证进行比对检验,从而为刻画嫌疑人及确定侦查方向提供思路.     

基于Bayes判别的手帕纸红外光谱鉴别

手帕纸是犯罪现场常见的物证之一,在法庭科学领域备受关注.为了实现对市场上手帕纸的快速分类鉴别的目的,本文采用了具有无损检验特点的傅里叶红外光谱,结合主成分分析(PCA)与Bayes判别对8种品牌96个手帕纸样本建立分类模型.结果表明,分别利用PCA和Bayes判别对样本进行分类的准确率并不理想,采用Bayes判别对PC...     

基于滤波器-机器学习的食欲抑制剂光谱信号预处理比较

对现场缴获的食欲抑制剂进行快速检验能够为案件调查提供线索和方向,同时机器学习算法开展物证的快速无损检验是法庭物证学的重要研究之一。红外光谱是最经典的快速无损检验方法,滤波器能够有效地除去原始谱图的噪声和背景干扰,从而提高模型的识别效果。本文收集了从实际案件中缴获的4种食欲抑制剂样本共计291份,运用快速傅里叶变换滤波器和希尔伯特变换滤波器对样本原始光谱数据进行降噪处理,同时借助朴素贝叶斯和随机森林模型建立分类模型,开展识别工作,从而筛选除噪效果最优的滤波器,同时比较了朴素贝叶斯和随机森林模型的识别效果。结果表明,经滤波器处理后原始光谱数据的识别率和稳定性显著提升,希尔伯特变换滤波器的除噪效果要比快速傅里叶变换滤波器好,随机森林模型的识别率和稳定性均要比朴素贝叶斯模型强,随机森林模型对经希尔伯特变化滤波器处理后的训练集识别率为96.33%,测试集识别率为95.89%。该方法通过滤波器有效地滤除谱图的噪声,提高了模型定性识别能力,对法庭科学中食欲抑制剂的快速鉴定有一定的参考意义。     

分子影像探针

分子影像是近年出现并迅速发展的一个生物医学领域,在疾病的治疗与诊断中发挥着重要作用。同时它又是一门交叉学科,涉及化学、医学、生物、计算机科学、放射科学、材料科学等。分子影像的发展除了需要先进的成像设备外,最关键的是合成新型而高效的成像探针。目前,分子影像探针广泛应用于科学研究和临床,并且也取得了巨大进步。本文主要综述了5种常见的分子影像探针:超声成像探针、X-射线计算机断层成像探针、光学成像探针、核磁共振成像探针、正电子发射计算机断层扫描成像探针,并对分子影像探针的应用进行了概述,最后对分子影像探针的发展进行了展望。     

硝基漆品牌厂家红外光谱鉴别及预测模型建立

在法庭科学领域,硝基漆的检验鉴别是一项重要的工作。为提高检验工作效率,提高分析可靠性,提出一种基于中红外光谱结合化学计量学的硝基漆鉴别方法。实验采集并获取长颈鹿等6种品牌共计59个样本的红外光谱数据,借助主成分分析、K近邻模型和判别分析构建分类模型。结果表明,PCA模型和K近邻模型对59个样本的区分能力相对较弱,判别分析模型的区分能力较强,实现了96.6%的准确区分和归类,分类结果理想。该方法能够快速,准确,无损地鉴别硝基漆,可为其他物证的检验鉴别提供一定的借鉴和参考。     

无透镜数字全息显微成像技术与应用

针对微结构和微光学元件等微小物体的表面定量检测,本文介绍了一种利用无透镜数字全息的快速、无损的显微成像方法。首先介绍了基于球面波的无透镜数字全息显微成像技术的基本原理,采用CCD作为光电转换器件,基于迈克尔逊干涉光路,设计了无透镜数字全息显微成像系统,利用反射镜构成折反式光路,系统结构简单、紧凑,提升了系统便携性。然后利用USAF1951分辨率板对构建的成像系统进行了标定实验,得出其横向分辨率为6.69μm,放大倍率为3.375,系统工作距离为12.0mm。此外,还对晶圆表面结构进行实际测量。实验验证了该系统的可行性和有效性,有望进一步应用于MEMS、微光学元件、光学元件等表面形貌的定量测量中。     

药毒物分析中磁性固相萃取技术的应用进展

磁性固相萃取是一种新型的样品前处理技术,具有萃取时间短、吸附能力强、有机溶剂使用量少、操作简单快捷等优点,已经广泛应用于样品的分离提纯.在简要介绍磁性固相萃取技术发展、材料制备的基础上,着重对国内外磁性固相萃取技术在药毒物分析方面的发展现状以及应用进展进行了综述,以期为法庭科学领域相关物证鉴定提供参考,为严厉打击相关违法犯罪活动提供科学理论与实践依据.     

Optical coherence tomography in biomedical research

Optical coherence tomography (OCT) is a noninvasive, high-resolution, interferometric imaging modality using near-infrared light to acquire cross-sections and three-dimensional images of the subsurface microstructure of biological specimens. Because of rapid improvement of the acquisition speed and axial resolution of OCT over recent years, OCT is becoming increasingly attractive for applications in biomedical research. Therefore, OCT is no longer used solely for structural investigations of biological samples but also for functional examination, making it potentially useful in bioanalytical science. The combination of in vivo structural and functional findings makes it possible to obtain thorough knowledge on basic physiological and pathological processes. Advanced applications, for example, optical biopsy in visceral cavities, have been enabled by combining OCT with established imaging modalities. This report gives an outline of the state of the art and novel trends of innovative OCT approaches in biomedical research in which the main focus is on applications in fundamental research and pre-clinical utilization.     

Recent advances in organic-dye-based photoacoustic probes for biosensing and bioimaging

Photoacoustic imaging(PAI) is a non-destructive biomedical imaging technology with broad application prospects. PAI combines the advantages of optical imaging and ultrasound imaging with high selectivity and deep penetration to overcome the high scattering limitation of light in tissues. This emerging technology also achieves high-resolution and high-contrast imaging of deep tissue in vivo. Recently, photoacoustic(PA) probes based on organic dyes have emerged prominently in biosensing and bioimaging due to their excellent optical properties and structural adaptability. This paper gives an outline of the basic PAI principles and focuses on the application of organic-dye-based PA probes for molecular detection and in vivo imaging. The advantages of PAI technology and the drawbacks of current PA probes are then summarized. Finally, the prospects for application are evaluated considering the potential challenges in the biomedical fields.     

面向持续观测的静止轨道高分辨率光学成像卫星应用模式设计与分析

为充分发挥静止轨道高分辨率光学成像卫星在持续观测应用方面的作用,在分析静止轨道卫星轨道特点、成像特点、成像优势的基础上,充分利用静止轨道高分辨率光学成像卫星任务响应速度快、重复探测频率高、姿态机动灵活等特点,提出了一种适合持续观测的星地一体应用模式,该模式综合考虑平时和应急两种态势,规划了5种具体的观测模式,可以为提高静止轨道高分辨率光学遥感卫星的规划和应用提供依据。     

Optical coherence tomography��current technology and applications in clinical and biomedical research

Optical coherence tomography (OCT) is a noninvasive imaging technique that provides real-time two- and three-dimensional images of scattering samples with micrometer resolution. By mapping the local reflectivity, OCT visualizes the morphology of the sample. In addition, functional properties such as birefringence, motion, or the distributions of certain substances can be detected with high spatial resolution. Its main field of application is biomedical imaging and diagnostics. In ophthalmology, OCT is accepted as a clinical standard for diagnosing and monitoring the treatment of a number of retinal diseases, and OCT is becoming an important instrument for clinical cardiology. New applications are emerging in various medical fields, such as early-stage cancer detection, surgical guidance, and the early diagnosis of musculoskeletal diseases. OCT has also proven its value as a tool for developmental biology. The number of companies involved in manufacturing OCT systems has increased substantially during the last few years (especially due to its success in opthalmology), and this technology can be expected to continue to spread into various fields of application.     

Design and development of a neutron/X-ray combined computed tomography system at Missouri S&T

A new method for non-destructive analysis has been developed using a combined neutron/X-ray imaging system at the Missouri Science & Technology Reactor (MSTR). The interactions of neutrons and X-ray photons with matter produce differing characteristic information, resulting in distinctly different visual images. In order to obtain a more comprehensive picture of the structural and compositional data for a desired object, a prototype imaging system has been designed which utilizes neutron and X-ray imaging simultaneously without obstructing the beam geometry for each imaging mechanism. The current system is optimized for the imaging of small to medium sized objects of 0.5–50 mm. This new imaging capability in place at the MSTR promises great advances in the field of non-destructive testing, especially for nuclear engineering, nuclear medical science, and material science research. In an imaging object, a range of atomic number values and thermal cross-sections may be present. Where multiple materials having similar atomic number and differing thermal cross-section or vice versa may be present, exclusive neutron or X-ray analysis may exhibit shortcomings in distinguishing interfaces. However, fusing the neutron image and X-ray image into a combined image offers the strengths of both and may provide a superior method of analysis. In this paper, a novel combined X-ray and neutron imaging system will be introduced for superior analysis of certain imaging objects. Design details of experimental set-up and examples of preliminary imaging tests from individual modality will be detailed.     

High-resolution, low-voltage SEM for true surface imaging and analysis

A novel design concept for the electron optical column has been implemented in the realization of a new ultra-high performance SEM. A compound magnetic/ electrostatic objective lens is at the heart of the high-performance column: the imaging aberrations of this new lens type decrease with decreasing beam energy. Any beam cross-over between the electron source (Schottky FE-gun) and the sample has been eliminated in order to avoid broadening of the beam energy spread (Boersch effect). A high beam energy is maintained throughout the column regardless of the electron probe energy selected by the operator. This protects the beam against the effect of stray fields and minimizes any loss of beam brigthness due to stochastic electron-electron interactions. The new SEM achieves outstanding resolution, particularly at the low beam energies (3 nm achievable at E_PE = 1 keV). The secondary electrons emitted by the sample are detected with very high efficiency by an internal annular detector situated above the final lens. Due to the low imaging aberration level, a high current can easily be focused in a very small probe, thus making the new SEM ideally suited for high-resolution, quantitative X-ray analysis.     

Scanning electrochemical microscopy in the 21st century. Update 1: Five years after

This Perspective is an update to our more extensive survey of scanning electrochemical microscopy (SECM) published in 2007. During this time, the SECM field retained its momentum by expanding into new areas and meeting the emerging scientific and technological challenges. Here we focus on most prominent developments such as high-resolution imaging, investigation of structures and processes on the nanoscale, alternative energy applications, and new approaches to solving "real world" problems. The fabrication of novel SECM probes and related theoretical advances are also discussed.     

Design,synthesis, characterization,photophysical and pH chemosensor studies of novel 2,4,6-trisubstituted pyridines

For the application in organic electronics as well as pH meters, a series of novel 2,4,6-trisubstituted pyridines have been synthesized by the reaction of substituted aromatic aldehydes and substituted 3-acetylcoumarin with ammonium acetate. The structures of all the new compounds were characterized by IR, NMR, and GC–MS analysis. The important photo physical prerequisites for organoelectronic such as optical absorption and thermal stability were determined for the synthesized molecules. Optical properties were studied by UV–visible absorption and fluorescence spectroscopy. Optical band gaps of the 2,4,6-trisubstituted pyridines were found to be around 3.01–3.06?eV as calculated from their onset absorption edge. The pH-dependent changes in the fluorescence intensity suggest that 2,4,6-trisubstituted pyridines are useful applicants in intracellular pH meters.     

基于低相干干涉的透镜厚度测量及生物影像研究进展

低相干光干涉测量技术作为重要的非接触测量方法之一,由于具有结构简单、测量速度快及分辨率高的优点,在光学系统的非接触测量及生物医学影像等前沿领域具有广阔的应用前景。本文对透镜组的光学元件中心厚度及空气间隔的非接触测量技术进行了总结,简述了基于OCT的生物医学影像方面研究现状,重点论述基于低相干光干涉法测量原理和研究进展,对比分析相关研究方法的优缺点和创新之处,并从系统结构和应用范围的角度对低相干干涉测量技术的发展趋势作了展望。     

中子成像技术在元素分析中的应用

中子成像作为一种快速、直观的无损检测技术,在核工业、航空航天、新能源、地质、考古、先进制造等多个领域得到广泛应用。中子成像利用中子不带电、穿透能力强、对轻元素敏感、可区分同位素和近邻元素等特性,非常适合开展含氢元素、近邻元素和同位素等材料的无损检测。本文概述了中子成像技术的基本原理及特点,并结合中国先进研究堆(CARR)中子成像装置上的应用案例, 重点介绍了国内外中子成像技术在储氢材料、燃料电池、岩石、核燃料元件、古代文物等领域的典型应用。随着中子成像技术的不断发展和广泛应用,有望为我国更多领域研究提供更强有力的技术支撑。