One pot synthesis of TiO_2:Eu^(3+) hierarchical structures as a highly specific luminescent sensing probe for the visualization of latent fingerprints

In the present work, TiO2:Eu^(3+) (1 mol%e11 mol%) nano powders(NPs) were prepared via a facile one-pot hydrothermal method by using Epigallocatechin Gallate(EGCG) as bio-surfactant. The optimized TiO2:Eu^(3+) (5 mol%) NPs can be used as fluorescent labeling agent for visualizing of latent fingerprints(LFPs) on various porous and non-porous surfaces. The obtained results exhibit well defined ridge details with high sensitivity, selectivity, and low background hindrance which show greater advantages as compared to conventional powders. We demonstrated the viability of high-performance security labels thorough excellent luminescence for practical anti-mimetic applications. Morphology of the prepared samples is highly dependent on pH, concentration of the bio-surfactant, temperature and time durations.Photoluminescence(PL) emission spectra exhibit intense red emission at ~ 615 nm due to electric dipole transition(~5 D_0/~7 F_2). Photometric(CIE and CCT) results clearly show the intense warm red emission of the optimized samples. Therefore, this work offers a superior and universal luminescent label, which can be applied to visualize miniature LFPs particulars for individualization and consequently display great prospective in forensic investigation.

Advances in the development and component recognition of latent fingerprints

Fingerprints have been used as an indispensable tool for personal identification in forensic investigations since the late 19 th century. At present, fingerprinting technology has moved away from its forensic roots and is incorporating a broader scientific range, e.g., material science, spectroscopy and spectral analysis, and even in vitro diagnosis. After a brief introduction to latent fingerprints, this mini-review presents the pioneering progresses of fingerprinting technologies including(i) material and electrochemical techniques, and(ii) spectral and spectroscopy imaging techniques and immunological techniques capable of both the visualization of a fingerprint and the detection of chemicals present in it. Finally, perspectives on this rapidly developing field are discussed.

Blue light-induced rare-earth free phosphors for the highly sensitive and selective imaging of latent fingerprints based on enhanced hydrophobic interaction

The demand for in-situ detection of latent fingerprints(LFPs)in ways of high sensitivity,high selectivity,high contrast,low cost and user-friendly is still urgent.To overcome this challenge,a moisture-stable,red-emitting fluoride phosphor K_(3)AlF_(6):Mn^(4+)(KAF:Mn^(4+))with an organic hydrophobic skin was prepared.The phosphor has a uniform and superfine morphology with excellent luminescence properties.More importantly,this non-ultraviolet(UV)or non-near infrared(NIR)induced phosphor was proved to be an ideal fluorescent label for LFP imaging,which is both friendly for touch DNA analysis and compatible to forensic light sources.The well-defined ridge details with little background interference on various surfaces were presented by the oleic acid(OA)modified KAF:Mn^(4+)(KAF:Mn^(4+)-OA)phosphor in few seconds using the powder dusting method.To confirm the high selectivity of KAF:Mn^(4+)-OA for LFP imaging,an efficient quantitative evaluation method is proposed with the aid of ImageJ&Origin software.Due to the superiority of the Mn^(4+)-doped fluoride for the rapid imaging of LFPs in terms of lowcost,high compatibility and good availability,it is expected to be a promising candidate for forensic science as well as fluorescence imaging in other fields instead of rare earth luminescent materials.

Synthesis of D-A typed AIE luminogens in isomeric architecture and their application in latent fingerprints imaging

Among the emitters in powder dusting to visualize the latent fingerprints(LFPs),aggregation-induced emission luminogens(AIEgens)are well employed for their high brightness and resistance to photobleaching.However,the serious background interference and low resolution still limit their fast development.Therefore,to further enhance the signal-to-noise ratio in LFPs imaging,especially to improve the analysis for level 3 details,donor-acceptor(D-A)typed AIEgens of DTPA-2,3-P,DTPA-2,5-P and DTPA-2,6-P are designed here.It is observed that strong emission covering from 450nm to 650nm can be obtained for all these molecules,especially that a high PLQY value of 10.06%in solids is achieved in DTPA-2,3-P.This is much higher than that of the other two cases(0.80%and 0.51%).By utilizing the DTPA-2,3-P in powder dusting,fluorescence imaging of LFPs can be clearly captured on both smooth and rough substrates.Moreover,confocal laser scanning microscope(CLSM)enables us to achieve high-resolution LFPs imaging in both 2D and 3D views,providing more detailed information of fingerprints pores in width,distance,distribution,and shapes.The results here demonstrate that highly emissive AIEgen of DTPA-2,3-P could be an excellent candidate for the visualization of fingerprints,thus providing the potential application in criminal investigation in the future.

基于Web of Science数据库的法庭科学领域潜指纹研究文献计量分析

本文采用文献计量分析的方法,通过对2001~2018年科学引文数据库的Web of Science数据库中法庭科学领域潜指纹研究文献进行统计,以此分析全球范围内法庭科学领域潜指纹研究情况。研究发现,全球在该领域的发文量整体呈现上升趋势。目前,法庭科学领域潜指纹研究热点主要有四个:传统潜指纹显现材料或技术的研究、潜指纹的信息化研究、纳米技术在潜指纹显现中的应用研究和针对潜指纹的残留物(如成瘾物质、爆炸物等)及遗留时间等构建新型潜指纹显现材料。我国在该领域的研究有一定的影响力,但在今后的研究中要注重高水平论文的发表,同时应加强与高水平研究机构之间的合作,带动该领域研究力量的整体提升,更好地为平安中国保驾护航。该分析可为我国相关领域的研究提供参考依据。

Exploring the Potential of Syzygium cumini(L.)Skeels(Jamun)Seed Powder as an Eco-Friendly Agent for Developing Friction Ridges on Porous and Nonporous Surfaces

Background:Development of obscured fingerprints on a diverse range of surfaces is a crucial aspect of forensic investigations.Aims and Objectives:In this particular study,the utilization of Syzygium cumini(L.)Skeels(Jamun)seed powder was examined for the purpose of revealing hidden fingerprints on a variety of surfaces,including both permeable and impermeable substrates.Materials and Methods:The seed powder was extracted using a simple process and was analysed using multiple analytical techniques.The efficacy of the jamun seed powder in developing latent fingerprints was evaluated.Results:The findings of this investigation demonstrate that the jamun seed powder was capable of producing fingerprint patterns of exceptional quality and clarity on numerous surfaces.Conclusion:This research highlights the potential use of jamun seed powder as a practical and effective alternative for the development of hidden fingerprints in forensic investigations,while also providing cost-effectiveness.

Green mediated synthesis of lanthanum doped zinc oxide:Study of its structural,optical and latent fingerprint application

The present paper summarises the synthesis of La3+doped zinc oxide nanoparticles using Aloe vera gel by solution combustion method and the characterization using a powder X-ray diffractometer(PXRD),a transmission electron microscope(TEM),an X-ray photometric spectrometer(XPS),a Raman spectrometer and their applications in optical devices and latent fingerprinting.PXRD pattern confirms the crystallite size of La3+doped ZnO varies from 13 to 20 nm.Crystallite size varies inversely with doping concentration.Photoluminescence properties are found to be the maximum for 2 mol% doping concentration.PL spectra extends the use of ZnO:La3+nanoparticles in blue green LED.These nanoparticles also have superior property as a fluorescent labels in fingerprints.

碳点在潜在指纹显影中的应用进展

碳点(CDs)是一种尺寸在10 nm以下的新型纳米材料,由于其独特的发光性能、低毒和环保等特点,在潜指纹检测中展现出了巨大的应用潜力。在潜指纹检测中,碳点的荧光特性可以帮助提高潜指纹的成像和识别能力。本文综述了碳点的合成方法、发光机理及其在潜指纹检测中的应用。通过合成方法优选、元素掺杂、前驱体调控、表面改性等手段可以调控碳点的荧光发射波长;再将碳点纳米粒子均匀分散在天然或常规材料上,所获得的碳点纳米复合材料可以避免因碳点纳米粒子聚集而引发的荧光淬灭现象,保留碳点的荧光性能,并且更适用于潜在指纹显现的常规操作。本文展望了在潜在指纹显影研究中碳点的未来发展方向,通过不断的改进和创新,期许为刑事科学技术领域的研究工作提供重要参考。

A Study on Automatic Latent Fingerprint Identification System

Latent fingerprints are the unintentional impressions found at the crime scenes and are considered crucial evidence in criminal identification.Law enforcement and forensic agencies have been using latent fingerprints as testimony in courts.However,since the latent fingerprints are accidentally leftover on different surfaces,the lifted prints look inferior.Therefore,a tremendous amount of research is being carried out in automatic latent fingerprint identification to improve the overall fingerprint recognition performance.As a result,there is an ever-growing demand to develop reliable and robust systems.In this regard,we present a comprehensive literature review of the existing methods utilized in latent fingerprint acquisition,segmentation,quality assessment,enhancement,feature extraction,and matching steps.Later,we provide insight into different benchmark latent datasets available to perform research in this area.Our study highlights various research challenges and gaps by performing detailed analysis on the existing state-of-the-art segmentation,enhancement,extraction,and matching approaches to strengthen the research.

金属沉积技术显现金属客体表面油潜指印的应用研究

[目的]研究金属沉积技术在金属客体表面油潜指印显现中应用的可行性,以解决油潜指印显现技术难题。[方法]通过碱性硫酸盐体系电镀铜和化学镀铜显现金属客体表面的油潜指印。研究了电镀液中硫酸镍的加入、电镀时间和电流密度对指印显现效果的影响。在锈蚀程度不同的金属客体表面考察了化学镀铜显现油潜指印的效果。[结果]采用含有8 g/L六水合硫酸镍的碱性硫酸盐体系在电流密度2 A/dm^(2)下电镀铜1 min时,油潜指印的显现效果良好。通过化学镀铜显现油潜指印时,可根据金属客体的锈蚀程度调整施镀时间。[结论]采用金属沉积技术显现金属客体表面油潜指印具有操作简便、显现效果良好的优势。其中化学镀铜可以成功显现锈蚀金属客体表面的油潜指印,满足公安现场勘查的实际需要。

荧光碳点复合材料显现潜手印综合实验设计

为了提高学生的证据意识和综合科研能力,设计了一个涵盖碳点复合材料合成、结构表征和潜手印显现应用的综合性实验。以柠檬酸、三乙烯四胺和罗丹明6G为原料合成荧光碳点材料,通过自组装策略将碳点纳米颗粒原位嵌入金属有机骨架中,从而获得固态下具有强荧光发射的碳点复合材料。利用扫描电子显微镜、荧光光谱仪、粉末X射线衍射仪等分析仪器对复合材料进行表征。采用粉末刷显法将制备的复合材料用于不同客体表面的潜手印显现中,对显现效果进行了分析和评价。教学内容紧密联系学术前沿和实际应用,有助于提高学生分析问题、解决问题的能力,培养创新的科研精神。

悬浮液显现技术应用于潜手印的研究进展

潜手印显现技术对案件侦破和司法鉴定起着重要的作用。根据客体表面的潜手印特点,需使用不同的显现技术,如悬浮液显现技术主要用于陈旧、潮湿或粘性的客体表面,而基于新兴纳米颗粒的悬浮液显现技术还因具备优异的灵敏度、信噪比、选择性等显现性能,日益受到重视。简要介绍了目前普遍使用的传统小颗粒悬浮液显现技术,较为详细地综述了近十几年来新兴纳米颗粒(如量子点、碳纳米点、稀土发光材料、纳米氧化物等)在手印显现方面的应用进展,并概述了悬浮液显现技术的操作方法,最后分析了该技术目前所面临的挑战和未来发展方向,为其在法庭科学、公安教育等领域的应用提供参考。

影响氨基黑10B显现指纹因素的系统探究

指纹是犯罪现场的最常见物证之一,更是对犯罪嫌疑人或受害人进行同一认证的重要物证,而由于犯罪现场的复杂性,不同的环境因素会对指纹的显现结果造成影响。以瓷砖上的新鲜血手印这一室内凶案现场常见的指纹物证为研究对象,探究了不同因素对氨基黑10B显现液显现指纹的影响,表明质量分数为0.60%氨基黑10B,质量分数为25%冰乙酸的显现液是显现瓷砖上新鲜血潜手印的最佳配方,同时,该配方也适用于不同显现方法、不同承痕客体、不同浓度和不同遗留时间的血手印和显现含有蛋白质的指纹。

基于重要区域定位与掩码的射频指纹可视化分析

针对时域脉冲信号样本的射频指纹提取与深度学习模型的可解释性,提出了一种基于Grad-CAM的重要区域可视化呈现方法,并通过重要区域的多次掩码测试,来分析重要区域对射频指纹识别结果的影响。基于10个辐射源的信号样本,对比了层数不同的两种ResNet模型的测试结果。测试发现该方法能够区分不同类型信号并呈现个体差异。分析表明,该方法能够发现不同辐射源发送相同信号时的重要区域定位差异,能可视化反映辐射源个体特征的空间距离,以及不同模型的特征表征与指纹定位准确度差异;同时发现对重要区域的掩码更容易产生误预测,证明特定信号存在与时频特征相关的射频指纹,并可辅助可视化定位影响射频指纹样本识别的关键点。

发射绿色荧光的钆氮掺杂碳点/水滑石纳米复合材料对潜在指纹的识别

碳点(CDs)是一种绿色纳米荧光剂,CDs分散在水溶液中,能够呈现出良好的荧光性能。由于聚集诱导而引发荧光猝灭效应,导致固态的CDs粉末的荧光消失,这一缺陷限制了CDs的实用性。一方面通过在CDs中掺杂其他元素的方式来改变CDs的荧光发射波长和荧光颜色,提高潜在指纹(LFPs)与基材背景间的对比度;另一方面将CDs分散在低值的水滑石表面,阻止CDs的聚集,从而避免了荧光猝灭现象的产生。以酒石酸为碳源、三乙烯四胺为氮源和GdCl_(3),采用水热法先制备钆氮掺杂CDs(Gd/N-CDs),然后再将Gd/N-CDs沉积在水滑石(Gd/N-CDs@H)表面上,制备出了发射绿色荧光的纳米复合材料,并用于LFPs的成像和识别。从表征结果可知,纳米级Gd/N-CDs在水滑石表面的良好分散克服了Gd/N-CDs在固态状态下的荧光猝灭,得到了固态光致发光荧光纳米复合材料。在450 nm光的激发下,Gd/N-CD@H能发射稳定、强烈的绿色荧光,并且在各种基底(如玻璃片、铜箔、瓷砖、塑料、铝箔和纸张)呈现出清晰的LFPs图像。基于Gd/N-CDs@H,新鲜和老化LFPs图案的高级别细节都可以清晰地识别出来,并且具有良好的清晰度和高对比度,无明显的背景干扰。

纳米材料显现潜在手印的研究进展

手印显现技术经过近百年的发展,已经能够对犯罪现场大多数潜在手印进行显现。但随着社会的发展和犯罪手段的更新,各种潜在手印的显现也对现有技术和材料提出了挑战。纳米材料因其拥有良好的吸附性、不容易漂浮于空中、适用性广和一般不影响DNA检验等优势,在显现潜在手印方面已获得了广泛关注。本文综述了各种新型纳米材料在潜在手印显现中的应用研究现状,重点阐述了金属纳米材料、非金属纳米材料、金属氧化物纳米材料以及其他纳米材料在潜在手印显现中的应用研究,并展望了纳米材料显现潜在手印技术的发展趋势,以期为进一步推进纳米材料显现潜在手印的实战应用提供参考。

Flux blended synthesis of novel Y2O3：Eu^3＋ sensing arrays for highly sensitive dual mode detection of LFPs on versatile surfaces

In the present communication,various fluxes blended Y2 O3：Eu3＋（5 mol%） nanopowders（NPs） were successfully fabricated by solution combustion method.PXRD pattern confirms body-centered cubic structure of the prepared samples.Energy band gap（Eg） of the fabricated products was estimated and is found to be in the range of 3.13-3.32 eV.Photoluminescence（PL） emission spectra exhibit sharp and intense peaks at ～579,592,614,657,704 nm corresponding to 5 D0→7 FJ（J = 0,1,2,3 and 4） transitions of Eu3＋ ions.Significance of fluxes for enhancing the PL emissions was extensively studied.Photometric studies of the prepared samples are located in pure red region.Optimized NPs were explored as a novel sensing agent for visualization of latent fingerprints（LFPs） on various surfaces including porous,semiporous and non-porous surfaces followed by powder dusting technique.Various experiments including aging,temperature,scratching and aquatic fresh water treatment tests were performed to evaluate applicability of the fabricated NPs.Visualized LFPs exhibit well defined ridge details including most authenticated sweat pores are also revealed with high sensitivity,selectivity,little background hindrance and less toxicity.Aforementioned results evidence that the method and fabricated NPs can be considered to be simple,rapid and economical and provide novel sensing platform for LFPs visualization in prospective forensic applications.

Rational design of monovalent ions （Li,Na,K） co-doped ZnAl2O4:Eu3+ nanocrystals enabling versatile robust latent fingerprint visualization

Alkali metal ions(M+ = Na+,Li+,K+) co-doped ZnAl2O4:Eu3+(5 mol%)(ZAE) nanopowders(NPs) were prepared via solution combustion route using Mimosa pudica(MP) leaves extract as a fuel. PXRD results of co-doped samples enhance the crystallinity and grain growth. Photoluminescence(PL) of the prepared ZAE and ZAE:M+(M+ = Na+, Li+, K+) NPs shows intense emission peaks in the range of 550-750 nm and ascribed to 5D0→7FJ(J=0-4) transitions of Eu3+ ions, respectively. A 2-fold enhancement in PL intensity was observed in Li+ co-doped samples. The optimized ZnAl2O4:Eu3+(5 mol%), Li+(1 wt%)(ZAEL)NPs were used to visualize LFPs on various porous, semi-porous and non-porous surfaces through robust powder dusting technique. The visualized latent fingerprints(LFPs) reveal well defined level 1-3 ridge characteristics under several tests such as fingerprint aging and fresh water treatment for various time durations. The obtained results clearly evidence that the prepared NPs are quite useful for multifunctional applications such as advanced forensic and solid state lightning.

铁红粉末在手印显现中的应用探究

通过使用铁红粉末对不同客体表面不同手印物质的潜在手印进行显现,表明铁红粉末对潜在皮脂手印和油脂手印显现效果较好;同时对于瓷砖、玻璃等非渗透性客体上的潜在手印显现效果也非常突出,并可显现7天内的潜手印;与传统粉末相比,适用范围更广泛,显现效果更明显,灵敏度更高。因此,铁红粉末能够单独作为显现材料用于手印显现中,可用于非渗透客体表面较新鲜的皮脂或油脂手印的显现,可在司法实践中推广使用。

Simultaneous extraction of level 2 and level 3 characteristics from latent fingerprints imaged with quantum dots for improved fingerprint analysis

Fingerprints are unique and life-long to everyone, so they occupy very important statuses in forensic science. However, due to the limit of current imaging technologies and instruments, recognition and matching of fingerprints are mostly based on their level 2 structures（bifurcation, crossover, and etc.）.Moreover, in real-world cases, fingerprints collected in the field are often incomplete or damaged, which adds further difficulty in fingerprint analysis. Quantum dots（QDs） are superior fluorescent imaging agents for latent fingerprints, which can provide both level 2 and level 3（sweat pores） details. Here, we used red-emitting N-acetylcysteine-capped Cd Te QDs as imaging agent for staining of eccrine LFPs. The numbers of level 2 and level 3 features that can be mapped are significantly larger than those obtained by cyanoacrylate fuming, a standard technique being adopted at forensic scene. Therefore, the level 2 and level 3 characteristics from QD-staining were simultaneously extracted for improved fingerprint analysis.A preliminary fingerprint matching based modified Pore Matching algorithm was thus developed based on the integration of both level 2 and level 3 characteristics. Satisfactory results of fingerprint matching were obtained, demonstrating the advantage of the QD-staining for advanced fingerprint analysis.