油红O显现潜在手印的影响因素分析

考察了浸泡时间、浸泡液体、溶液储存时间和使用次数对油红O显现不同纸张上潜在手印的效果的影响,证实了浸泡液体和溶液储存时间对手印显现效果影响小,浸泡时间和溶液使用次数对显现效果影响大,优化了油红O显现手印的处理程序,使用该方法处理潮湿客体上的潜在手印应及时使用新配制的溶液进行显现。     

潮湿纸张类客体上潜在手印的显现方法研究进展

纸张类是犯罪现场常见客体之一,对于纸张类客体上遗留的潜在手印,常采用茚三酮、DFO、茚二酮等常见的氨基酸指示剂进行显现。但犯罪现场环境复杂,若遗留有潜在手印的纸张已浸湿或长期处于潮湿环境中,那么手印遗留物中的水溶性成分会部分或全部溶解于水中,从而限制了上述方法的使用。因此,对于潮湿纸张类客体上潜在手印的显现,一直都是研究的难点与重点。旨在对潮湿纸张类客体上潜在手印的显现方法进行综述,以便于开展后续研究。     

基于磁性纳米材料显现潜在手印的研究进展

手印作为指认犯罪嫌疑人的重要物证,通过对犯罪现场的潜在手印进行显现比对,为公安司法机关提供侦查线索和法庭证据。近年来,将新型磁性纳米材料应用于潜在手印显现技术的研究成为法庭科学研究者及刑侦人员关注的热点,与传统手印显现技术相比,磁性纳米手印显现技术具有可回收、低DNA毒性、高灵敏度、显现方式多样等突出优点。从显现原理、合成方法及对潜在手印的显现效果等方面重点阐述了常规磁性纳米粉末、磁性小颗粒悬浮(SPR)试剂、磁性掺杂纳米荧光材料、无机-有机杂化磁性纳米材料、具有核壳构型的磁性纳米材料、基于免疫反应的磁性纳米材料等6类磁性纳米材料,并对存在的问题进行了讨论,展望了新型磁性纳米材料应用的未来发展趋势,为犯罪现场潜在手印的显现提供了重要的参考和借鉴。     

茚三酮和指甲花醌显现纸张上汗潜手印比较研究

基于"绿色化学"理念,为了评估天然植物提取物质指甲花醌显现纸张上汗潜手印的能力,将其与茚三酮显现纸张上汗潜手印的能力进行比较.采用茚三酮和指甲花醌分别对复印纸、热敏纸、胶版纸3种纸张上遗留时间分别为1、5和10 d的汗潜手印样本进行显现,从显现原理、适用范围、试剂配方、操作流程、显现效果、经济性、安全性等角度对这两种方...     

碳酸钙小颗粒试剂显现潮湿手印研究

以碳酸钙为主要成分配制了用于显现潜在手印的新型小颗粒试剂,研究了手印遗留时间、手印水浸时间、不同浸泡成分等外界条件对碳酸钙小颗粒试剂显现效果的影响,并与同类其它小颗粒试剂进行了对比试验,结果表明,碳酸钙小颗粒试剂对于水浸以及常见饮料浸湿的潜在手印具有良好显现效果,为潜在物证的提取提供了一种新方法。     

荧光“502”显现潜在手印研究

探究一种新型的荧光“502”用于显现潜在手印的方法.实验对该荧光“502”显现常见客体上潜在手印的效果以及显现手印的灵敏度进行了研究,并比较了这种同步熏显染色的方法与罗丹明6G、Ardrox荧光液、基础黄40二次染色方法显现手印的效果.结果表明,这种荧光“502”显现潜在手印效果较好,用Coherent Tracer激光器激发后,在橙红色护目镜下可以观察到强烈的黄色或橙黄色荧光,显出的手印纹线清晰,与背景反差明显,可以观察到手印纹线上的汗孔.荧光“502”显现潜在手印的方法操作简便,没有后续二次染色的过程,因此不会破坏手印,可以确保纹线及其细节特征的完整性.     

基于疏水性TiO2纳米颗粒的悬浮液手印显现研究

利用偶联剂N-辛基三甲氧基硅烷(KH-318)对TiO₂纳米颗粒进行改性,制备表面改性的TiO₂纳米颗粒悬浮液,考察反应温度和反应时间对亲油化度的影响,使用光学显微镜考察在不同制备条件下改性疏水性TiO₂纳米颗粒悬浮液对手印显现效果的影响。结果表明,改性的TiO₂纳米颗粒悬浮液的疏水性在45℃反应2 h时最好,显现潜在手印的效果优异,可呈现出清晰的指纹三级特征。有机官能团通过Ti—O—Si化学键成功接枝到TiO₂纳米颗粒表面,且改性后的TiO₂纳米颗粒对潜在手印表面的脂类等物质具有良好的靶向吸附能力。改性的疏水性TiO₂纳米颗粒悬浮液的性质非常稳定,适合皮脂及油质等手印的高灵敏度显现,在化学及法庭科学领域具有较好的应用前景。     

热敏磁票纸表面潜在手印显现方法研究

随着热敏磁票纸的市场应用呈现加速发展的趋势,本文主要研究热敏磁票纸这种较新客体上常见手印的显现方法并对遗留不同时间的潜在手印显现效果进行探讨。使用金粉、磁性粉末刷显,"502"胶熏显,碘熏以及红外加热法和真空镀膜等方法对热敏磁票纸正面潜在手印均能有效显出,得到较清晰连贯纹线;使用金粉刷显、"502"胶熏显后染色对客体反面手印显现可以增强纹线和背景的反差,得到较好显现效果。粉末刷显法、真空镀膜法、碘熏法、红外加热法对于热敏磁票纸上不同遗留时间的潜在手印有较好的显现效果,具有一定的鉴定价值。     

混合显现液对纸张客体潜在手印显现效果的探究

通过初步实验筛选出0.5%硝酸银乙醇溶液与1%茚三酮乙醇溶液对渗透性客体显现效果最佳,然后配置茚三酮、硝酸银乙醇混合液对牛皮纸、白纸、报纸三种客体表面上遗留的新鲜和陈旧汗潜指印进行显现。结果表明硝酸银、茚三酮乙醇混合显现液能显现纸张等渗透性客体上的新陈汗潜手印,且与单个试剂显现效果比较,混合显现液显现效果优于单个试剂的显现效果。     

渗透性客体上汗潜手印与金属遗留印迹联合显现方法研究

通过考察茚二酮手印显现法与金属遗留印迹显现法之间的相互影响以及两种方法对纸张上汗潜手印与金属遗留印迹显现效果的影响,建立汗潜手印与金属遗留印迹的联合显现方法。实验结果表明,经茚二酮手印显现法与金属工具遗留印迹显现法显出的印迹在颜色和细节特征反映上均互不干扰,且先显现汗潜手印、后显现金属遗留印迹是复合印迹联合显现的最佳顺序。该联合显现方法的建立不仅弥补了渗透性客体上金属遗留印迹显现中手印反映不完整的缺点,而且还使手印中微量金属信息得以利用,从而为证明犯罪嫌疑人与金属工具之间关联性提供了更强有力的证据。     

A new chemical aid for criminal investigation: dyes and latent prints

Criminalistics is a field in which there are many opportunities for the practical application of chemical reagents and the use of analytical methods that provide answers to enigmas at crime scenes. Common reagents in biochemical and medical test methods can be useful for criminalistics (forensic science). Dyes are one type of reagent that can be used in obtaining crime scene evidence. This work describes a new application of CI Solvent Black 3 dye in the location of latent fingerprints. The results show that CI Solvent Black 3 can be successfully applied in the location and development of recent and non-recent latent fingerprints on porous surfaces.     

Non‐toxic luminescent carbon dot/poly(dimethylacrylamide) nanocomposite reagent for latent fingermark detection synthesized via surface initiated reversible addition fragmentation chain transfer polymerization

Here, non‐toxic luminescent carbon nanoparticles, namely carbon dots (C‐dots), were facilely synthesized via a one‐pot hydrothermal route. Raman, Fourier transform infrared, fluorescence, carbon NMR and X‐ray photoelectron spectroscopies revealed that the C‐dots possessed a graphitic‐like core with an oxidized surface. The oxidized surface of the C‐dots allowed for functionalization of the C‐dots with a 2‐methyl‐2‐[(dodecylsulfanylthiocarbonyl)sulfanyl]propanoic acid chain transfer agent. Poly(N,N‐dimethylacrylamide) (p(DMA)) was then grafted from the C‐dot surface via surface initiated reversible addition fragmentation chain transfer (RAFT) polymerization. The resulting luminescent C‐dot/polymer nanocomposite, C‐dot/p(DMA), was analyzed using UV?visible and fluorescence spectrometry verifying that the functionalized surface was responsible for the C‐dots' luminescence. This C‐dot/p(DMA) nanocomposite was water soluble and was used as a solution for the luminescent detection of latent fingermarks deposited on non‐porous aluminium foil substrates. © 2014 Society of Chemical Industry     

Near perfect visual compensation for atmospheric color distortions

Light is scattered and absorbed in the atmosphere producing visual effects that increase with viewing distance. Contrast and chromatic diversity decrease with distance, thereby modifying the way objects and scenes are perceived. Although some perceptual compensation to produce color constancy of individual surfaces has been reported, it is unclear to what extent unknown original images can be visually inferred from their distorted versions, that is, how much these effects can be discounted by the visual system. We investigated this issue with a paradigm akin to the paper-matching paradigm used in color constancy studies but with complex natural images. Hyperspectral data from 11 natural scenes were used to simulate their colors for distances up to 2000 m using a precise physical model of the effects of atmosphere. In each trial of the experiment, observers viewed the range of simulated images derived from one scene displayed on a calibrated monitor and selected the one perceived as more natural, without color distortion. Pooling data across scenes and observers showed that the image selected as more natural was very close to the undistorted one, corresponding to a simulated distance of only 2 m. These results suggest that observers are sensitive to changes in the naturalness of colors due to atmospheric effects and, crucially, can retrieve the original chromatic content with good accuracy revealing an efficient form of color constancy.     

CdS量子点的合成和指纹检测研究

本工作提出以谷胱甘肽(GSH)为修饰试剂合成了高量子产率的硫化镉量子点,并应用其对非渗透性客体玻璃上的潜在指纹进行显现。结果发现,显现出的指纹清晰可辨,且与背景之间的反差好。该方法具有简便、快速、灵敏、安全、经济等特点。     

Gold nanoparticles/single-stranded DNA-reduced graphene oxide nanocomposites based electrochemical biosensor for highly sensitive detection of cholesterol

High density and uniform distribution of the gold nanoparticles functionalized single-stranded DNA modified reduced graphene oxide nanocomposites were obtained by non-covalent interaction. The positive gold nanoparticles prepared by phase inversion method exhibited good dimensional homogeneity and dispersibility, which could readily combine with single-stranded DNA modified reduced graphene oxide nanocomposites by electrostatic interactions. The modification of single-stranded DNA endowed the reduced graphene oxide with favorable biocompatibility and provided the preferable surface with negative charge for further assembling of gold nanoparticles to obtain gold nanoparticles/single-stranded DNA modified reduced graphene oxide nanocomposites with better conductivity, larger specific surface area, biocompatibility and electrocatalytic characteristics. The as-prepared nanocomposites were applied as substrates for the construction of cholesterol oxidase modified electrode and well realized the direct electron transfer between the enzyme and electrode. The modified gold nanoparticles could further catalyze the products of cholesterol oxidation catalyzed by cholesterol oxidase, which was beneficial to the enzyme-catalyzed reaction. The as-fabricated bioelectrode exhibited excellent electrocatalytic performance for the cholesterol with a linear range of 7.5−280.5 μmol·L⁻¹, a low detection limit of 2.1 μmol·L⁻¹, good stability and reproducibility. Moreover, the electrochemical biosensor showed good selectivity and acceptable accuracy for the detection of cholesterol in human serum samples.     

Thermal and flame‐retardant properties of polyester fabric grafted with polyanilines

The chemical grafting of polyaniline, poly(o‐anisidine), and poly(o‐toluidine) on polyester fabric was carried out with ammonium peroxodisulfate in an acidic medium. The formation of the grafted fabric substrate was confirmed with reflectance spectroscopy, Fourier transform infrared spectroscopy, weight‐loss studies, and conductivity measurements. The grafting percentage and efficiency percentage were determined for the different grafted substrates. The thermal and flame‐retardant properties of these grafted substrates were elucidated. Thermogravimetric analysis thermograms and derivative thermogravimetry curves showed that the grafted substrates had a higher thermal stability and char‐residue percentage at 700°C. The grafted substrates showed a higher activation energy of thermal decomposition than the nongrafted substrates. The grafted substrates showed good flame retardancy, which was evident from the increase in the limited oxygen index in comparison with that of the nongrafted substrate. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1981–1988, 2004     

Additive manufacturing of architected catalytic ceramic substrates based on triply periodic minimal surfaces

The exhibited geometry of catalytic substrates can have a significant influence on the chemical activity and efficiency. Controlling their geometry can be challenging using the traditional techniques. In this work, we propose new and novel catalytic substrates with architected and controllable topologies based on the minimal surfaces framework. A novel design approach and an additive manufacturing (AM) technique were proposed to manufacture the catalytic substrates using ceramic materials. After 3D printing, their mechanical and flow properties were investigated experimentally. An elastic-plastic-damage coupled model was employed to investigate the underlying deformation mechanism of the investigated substrates. Results showed that the CLP substrate exhibited the highest mechanical properties as well as the least pressure drop among the tested substrates. Also, numerical simulations showed that the strut-based substrates exhibit stress localization which leads to faster failure, while stress is distributed more homogeneously in the sheet-based substrates. While the model showed to have a good agreement in the experimental and simulation stress-strain responses, the damage mechanism was not fully captured by the numerical simulations. This was attributed mainly to the process-induced defects in the form of microcracks and microvoids that can alter the nature of deformation and damage.     

Performance enhancement of GaN-based light emitting diodes by transfer from sapphire to silicon substrate using double-transfer technique

ABSTRACT: GaN-based light emitting diodes (LEDs) fabricated on sapphire substrates were successfully transferred onto silicon substrates using a double-transfer technique. Compared with the conventional LEDs on sapphire, the transferred LEDs showed a significant improvement in the light extraction and thermal dissipation, which should be mainly attributed to the removal of sapphire and the good thermal conductivity of silicon substrate. Benefited from the optimized wafer bonding process, the transfer processes had a negligible influence on electrical characteristics of the transferred LEDs. Thus, the transferred LEDs showed a similar current-voltage characteristic with the conventional LEDs, which is of crucial importance for practical applications. It is believed that the double-transfer technique offers an alternative way to fabricate high performance GaN-based thin-film LEDs.     

Conjugated fluorescent polymer sensor for proteolytic activity detection with designed specificity

A portable fluorescence assay for direct endopeptidase activity detection has been developed with the use of a cyclophane‐based conductive conjugated fluorescent polymer and peptide substrates. The substrates, carrying internal quenching amino acid, were designed to be cleaved in a sequence‐specific manner by a protease of interest. Intact substrates were incapable of quenching the fluorescence of the polymer due to steric constraints. Upon specific cleavage, the quencher became exposed and could interact with the ring structure of the fluorescent polymer, disrupting the conjugation and quenching the fluorescence along the polymer chain. The approach was developed using a model Glu‐C endopeptidase from Staphylococcus aureus strain V8, detected in the picomolar to micromolar concentration range. The developed assay was tested for the detection of endopeptidase activity of botulinum toxin. The feasibility study showed that botulinum neurotoxin (BoNT)‐A could be detected down to picomolar concentration, with limit of detection of 5 pg, or 33 amol in 5 µL of sample, and a total assay time under 2 h. The assay exhibited high specificity and no cross‐reactivity with BoNT‐B was detected. Following this proof‐of‐concept work, the assay can be further optimized and expanded to differentiate between various botulinum toxin serotypes in their active proteolytic form, or modified for detection of proteases with other specificities. © 2015 Society of Chemical Industry