Overlapping latent fingermarks constitute a serious challenge to database related recognition and matching algorithms in biometry, forensic and crime scene investigations. Mass spectrometry imaging (MSI) is a powerful...Overlapping latent fingermarks constitute a serious challenge to database related recognition and matching algorithms in biometry, forensic and crime scene investigations. Mass spectrometry imaging (MSI) is a powerful tool for deciphering and analyzing overlapping fingermarks based on the individual chemical information of each deposit. Fingermark MSI in practice still requires a subjective judgment of an MSI expert, such that rapid analysis, automation, standardization, and a quantitative evaluation of the complete detection and separation process of overlapped fingermarks from MSI data sets is the ultimate goal and will be necessary to become an accepted process in criminal investigations and law enforcement. Here we investigated the feasibility and efficiency of different statistical approaches for the separation of overlapped latent fingermarks based on MSI data. Entropy analysis of generated m/z-images was used to evaluate the results obtained from the statistical analysis. Furthermore, we demonstrate and discuss the opportunity to reconstitute and separate overlapping fingermarks by discrete scanning at selected x,y-positions defined from a previous image analysis using a more simple schema based on visible and therefore optical distinguishable overlapped ink-based fingermarks. The overlapped latent fingermarks were developed by rapid gold sputter coating and analyzed by laser based MSI, without (organic) matrix preparation. Latent finger marks can be transferred from the substrate/surface with and conserved on a soft gold sputtered soft membrane at low temperatures.展开更多
Traditional fingermark developing methods are unsuitable for developing and extracting latent blood fingermarks on dark surfaces at crime scene because of their ineffectiveness or tedious operation procedures.In the p...Traditional fingermark developing methods are unsuitable for developing and extracting latent blood fingermarks on dark surfaces at crime scene because of their ineffectiveness or tedious operation procedures.In the present work,an effective and simple method was developed to serve this purpose using a suspension of monodisperse silica nanoparticles(MSNs).A suspension of 0.1 g/mL of MSNs was prepared by dispersing MSNs ultrasonically into an ethanol solution containing 1.0%Tween 80 and then uniformly sprayed onto the latent blood fingermarks on black plastic bags.Approximately 20 s later,ethanol was sprayed to clean the superfluous developing liquid.After the ethanol had evaporated,the latent fin-germarks became visible as a result of the photonic crystal effect produced by the MSNs that had adsorbed to the fingermark ridges.The developed fingermarks were then photo-graphed using a digital camera under a white or monospectral light source,revealing fine ridges and clear fingermark details.This novel,simple and effective method uses the pho-tonic crystal effect of MSNs to develop latent blood fingermarks without the need for sur-face functionalization and conjugation to dye or fluorescently label molecules.The method can detect latent blood fingermarks that have been retained on a black plastic bag surface for at least 30 d.Given the simplicity and effectiveness of the developed method,MSNs may be a useful alternative material for use in developing latent fingermarks.Further research on the topic is warranted.展开更多
A method for in situ preparation of fluorescent gold nanoclusters(Au NCs) with bovine serum albumin/montmorillonite composite powder(Au NC-BSA/MMT) was developed, and the products were used to detect latent fingermark...A method for in situ preparation of fluorescent gold nanoclusters(Au NCs) with bovine serum albumin/montmorillonite composite powder(Au NC-BSA/MMT) was developed, and the products were used to detect latent fingermarks. In this work, Au NCs were "grown" both inside and on the surface of BSA/MMT clay using one-step reduction of HAu Cl4 by BSA. The as-prepared Au NC-BSA/MMT nanocomposites emit intensive red fluorescence under the excitation of UV-visible light and show stable chemical features and low toxicity. The obtained fluorescent powders were characterized by UV-visible absorption spectroscopy,fluorescence spectroscopy, infrared spectroscopy, transmission electron microscopy/high-resolution transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction to depict their sizes, structural information and optical features. Given their environmentally friendly preparation, simple operation, low cost, efficient UVvisible radiation-dependent photoluminescence and good affinity with finger residues, the in situ synthesized Au NC-BSA/MMT nanocomposite powders were used as an alternative fluorescent developing reagent for developing latent fingermarks deposited on various object surfaces(such as glass, aluminum foil, painted metal, plastic products and weighing papers) for individual identification. As results, the developed fingermarks with clear patterns and satisfactory level-2(minutiae points) and level-3(sweat pores) ridge details were obtained. Notably, treated prints could be excited by red light and emitted near infrared fluorescence, which was beneficial to avoid background interference and reduce the damage caused by UV light. With the advantages of the simple preparation process and good enhancement performance for latent fingermarks, the proposed method might be used in the preparation of various fluorescent probes for detecting trace evidence in forensic sciences.展开更多
Cyanoacrylate fluorescent staining has become a common method for developing latent fingermarks on light-coloured or white objects.The method requires two steps and skilled operation,and the handling process has the r...Cyanoacrylate fluorescent staining has become a common method for developing latent fingermarks on light-coloured or white objects.The method requires two steps and skilled operation,and the handling process has the risk of damaging the ridge details or even biological samples.To take full advantage of the high-sensitivity fluorescence,recent research efforts on fluorescent cyanoacrylate have aimed to avoid rinsing after staining,add fluorescence to the cyanoacrylate,increase the fluorescence intensity and broaden the fluorescence spectral range.PolyCyano UV is a novel product that can be used to overcome the disadvantages associated with progressing to one-step fuming to directly develop fingermarks.To explore the optimal development conditions and application effects of PolyCyano UV,thermogravimetric differential thermal analysis,fluorescence spectroscopy and control variable analysis are used to determine and analyse the best conditions for using the reagent,including temperature,fluorescence excitation band,relative humidity and fuming concentration.The temperature range of the one-step fuming development method is 212.14℃–275.16℃,the wavelength range of the excitation light source is 235–580 nm,the relative humidity is 60%–80%,the concentration of the fume is 1–3g/m^(3) and the specific value is related to the surface properties of the object and the aged time of the fingermarks.Additionally,fluorescence spectroscopy shows that the excitation wavelength range of the light source is 235–580nm.Based on the best fuming condition,many common objects were selected to proceed to the application experiments,which allowed for a comparison with the traditional visualisation method,namely the Cyanobloom reagent+dyeing two-step development method.The comparison showed that latent fingermarks on most non-porous smooth surfaces,especially on light-coloured or white objects,were developed successfully.In addition,a comparative study with the conventional cyanoacrylate glue–fluorescent staining experiments showed that the effect of dyeing afterwards with Rhodamine 6G is better than the one-step method.The effect of dyeing with BBD is basically the same as that of the one-step method.展开更多
Background:Fingermark is an individual’s primary identification source.It is helpful in determining individuals involved in illegal activities and is frequently encountered in clandestine laboratories.During forensic...Background:Fingermark is an individual’s primary identification source.It is helpful in determining individuals involved in illegal activities and is frequently encountered in clandestine laboratories.During forensic investigation,the critical question to be answered is whether a fingermark was left on a surface before or after the initiation of an unlawful activity.Aims and Objectives:This study aimed to investigate the visualization of methamphetamine-contaminated fingermarks on glass surfaces and estimate the immediacy of their depositions.Materials and Methods:In this study,the prior-deposition contaminated fingermarks,i.e.,fingermarks deposited a surface priorly contaminated by methamphetamine,and the postdeposition contaminated fingermarks,i.e.,fingermarks deposited on a clean surface but subsequently contaminated with methamphetamine were visualized and compared using Field Emission Scanning Electron Microscope(FESEM).Results:Under FESEM,the latent fingermarks and the crystalline structure of methamphetamine were clearly visualized.The postdeposition contaminated fingermarks appeared in smudge conditions in all the three replicate samples,where the ridge and nonridge areas could not be well-distinguished.On the contrary,the prior-deposition contaminated fingermark demonstrated distinct separations between ridges and nonridges.However,the application of fingerprint powders reduced the possibility to determine the immediacy of deposition.Conclusion:To conclude,both prior-deposition contaminated fingermarks and postdeposition contaminated fingermarks can be discriminated,providing information on the instance when a fingermark was left on a surface.展开更多
A GC-MS method for analysis of amino acid compositions in fingermark residues was established.Sample was extracted by ethanol and derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide for 6 min at 600 W of mi...A GC-MS method for analysis of amino acid compositions in fingermark residues was established.Sample was extracted by ethanol and derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide for 6 min at 600 W of microwave.The recovery,repeatability,detection limit,and linear equation were investigated.The results indicated the method was rapid,sensitive and effective,and was very helpful for the development of fingerprint technique.展开更多
文摘Overlapping latent fingermarks constitute a serious challenge to database related recognition and matching algorithms in biometry, forensic and crime scene investigations. Mass spectrometry imaging (MSI) is a powerful tool for deciphering and analyzing overlapping fingermarks based on the individual chemical information of each deposit. Fingermark MSI in practice still requires a subjective judgment of an MSI expert, such that rapid analysis, automation, standardization, and a quantitative evaluation of the complete detection and separation process of overlapped fingermarks from MSI data sets is the ultimate goal and will be necessary to become an accepted process in criminal investigations and law enforcement. Here we investigated the feasibility and efficiency of different statistical approaches for the separation of overlapped latent fingermarks based on MSI data. Entropy analysis of generated m/z-images was used to evaluate the results obtained from the statistical analysis. Furthermore, we demonstrate and discuss the opportunity to reconstitute and separate overlapping fingermarks by discrete scanning at selected x,y-positions defined from a previous image analysis using a more simple schema based on visible and therefore optical distinguishable overlapped ink-based fingermarks. The overlapped latent fingermarks were developed by rapid gold sputter coating and analyzed by laser based MSI, without (organic) matrix preparation. Latent finger marks can be transferred from the substrate/surface with and conserved on a soft gold sputtered soft membrane at low temperatures.
基金This work was supported by Natural Science Foundation of Fujian,China[grant number 2017J05019].
文摘Traditional fingermark developing methods are unsuitable for developing and extracting latent blood fingermarks on dark surfaces at crime scene because of their ineffectiveness or tedious operation procedures.In the present work,an effective and simple method was developed to serve this purpose using a suspension of monodisperse silica nanoparticles(MSNs).A suspension of 0.1 g/mL of MSNs was prepared by dispersing MSNs ultrasonically into an ethanol solution containing 1.0%Tween 80 and then uniformly sprayed onto the latent blood fingermarks on black plastic bags.Approximately 20 s later,ethanol was sprayed to clean the superfluous developing liquid.After the ethanol had evaporated,the latent fin-germarks became visible as a result of the photonic crystal effect produced by the MSNs that had adsorbed to the fingermark ridges.The developed fingermarks were then photo-graphed using a digital camera under a white or monospectral light source,revealing fine ridges and clear fingermark details.This novel,simple and effective method uses the pho-tonic crystal effect of MSNs to develop latent blood fingermarks without the need for sur-face functionalization and conjugation to dye or fluorescently label molecules.The method can detect latent blood fingermarks that have been retained on a black plastic bag surface for at least 30 d.Given the simplicity and effectiveness of the developed method,MSNs may be a useful alternative material for use in developing latent fingermarks.Further research on the topic is warranted.
基金supported by the National Natural Science Foundation of China(51401174)the National Social Science Foundation of China(16AYY015)the Scientific Research Funds of Southwest University of Political Science and Law(2015XZQN-32)
文摘A method for in situ preparation of fluorescent gold nanoclusters(Au NCs) with bovine serum albumin/montmorillonite composite powder(Au NC-BSA/MMT) was developed, and the products were used to detect latent fingermarks. In this work, Au NCs were "grown" both inside and on the surface of BSA/MMT clay using one-step reduction of HAu Cl4 by BSA. The as-prepared Au NC-BSA/MMT nanocomposites emit intensive red fluorescence under the excitation of UV-visible light and show stable chemical features and low toxicity. The obtained fluorescent powders were characterized by UV-visible absorption spectroscopy,fluorescence spectroscopy, infrared spectroscopy, transmission electron microscopy/high-resolution transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and X-ray diffraction to depict their sizes, structural information and optical features. Given their environmentally friendly preparation, simple operation, low cost, efficient UVvisible radiation-dependent photoluminescence and good affinity with finger residues, the in situ synthesized Au NC-BSA/MMT nanocomposite powders were used as an alternative fluorescent developing reagent for developing latent fingermarks deposited on various object surfaces(such as glass, aluminum foil, painted metal, plastic products and weighing papers) for individual identification. As results, the developed fingermarks with clear patterns and satisfactory level-2(minutiae points) and level-3(sweat pores) ridge details were obtained. Notably, treated prints could be excited by red light and emitted near infrared fluorescence, which was beneficial to avoid background interference and reduce the damage caused by UV light. With the advantages of the simple preparation process and good enhancement performance for latent fingermarks, the proposed method might be used in the preparation of various fluorescent probes for detecting trace evidence in forensic sciences.
基金supported by the Second Batch of Teaching Reform Research Project of Zhejiang Higher Education during the 13th Five-Year Plan period(No.jg20190493)Education Science Planning of Zhejiang Province in 2021 Research Project(2021SCG280).
文摘Cyanoacrylate fluorescent staining has become a common method for developing latent fingermarks on light-coloured or white objects.The method requires two steps and skilled operation,and the handling process has the risk of damaging the ridge details or even biological samples.To take full advantage of the high-sensitivity fluorescence,recent research efforts on fluorescent cyanoacrylate have aimed to avoid rinsing after staining,add fluorescence to the cyanoacrylate,increase the fluorescence intensity and broaden the fluorescence spectral range.PolyCyano UV is a novel product that can be used to overcome the disadvantages associated with progressing to one-step fuming to directly develop fingermarks.To explore the optimal development conditions and application effects of PolyCyano UV,thermogravimetric differential thermal analysis,fluorescence spectroscopy and control variable analysis are used to determine and analyse the best conditions for using the reagent,including temperature,fluorescence excitation band,relative humidity and fuming concentration.The temperature range of the one-step fuming development method is 212.14℃–275.16℃,the wavelength range of the excitation light source is 235–580 nm,the relative humidity is 60%–80%,the concentration of the fume is 1–3g/m^(3) and the specific value is related to the surface properties of the object and the aged time of the fingermarks.Additionally,fluorescence spectroscopy shows that the excitation wavelength range of the light source is 235–580nm.Based on the best fuming condition,many common objects were selected to proceed to the application experiments,which allowed for a comparison with the traditional visualisation method,namely the Cyanobloom reagent+dyeing two-step development method.The comparison showed that latent fingermarks on most non-porous smooth surfaces,especially on light-coloured or white objects,were developed successfully.In addition,a comparative study with the conventional cyanoacrylate glue–fluorescent staining experiments showed that the effect of dyeing afterwards with Rhodamine 6G is better than the one-step method.The effect of dyeing with BBD is basically the same as that of the one-step method.
基金Universiti Sains Malaysia RUI grant(1001/PPSK/8012236).
文摘Background:Fingermark is an individual’s primary identification source.It is helpful in determining individuals involved in illegal activities and is frequently encountered in clandestine laboratories.During forensic investigation,the critical question to be answered is whether a fingermark was left on a surface before or after the initiation of an unlawful activity.Aims and Objectives:This study aimed to investigate the visualization of methamphetamine-contaminated fingermarks on glass surfaces and estimate the immediacy of their depositions.Materials and Methods:In this study,the prior-deposition contaminated fingermarks,i.e.,fingermarks deposited a surface priorly contaminated by methamphetamine,and the postdeposition contaminated fingermarks,i.e.,fingermarks deposited on a clean surface but subsequently contaminated with methamphetamine were visualized and compared using Field Emission Scanning Electron Microscope(FESEM).Results:Under FESEM,the latent fingermarks and the crystalline structure of methamphetamine were clearly visualized.The postdeposition contaminated fingermarks appeared in smudge conditions in all the three replicate samples,where the ridge and nonridge areas could not be well-distinguished.On the contrary,the prior-deposition contaminated fingermark demonstrated distinct separations between ridges and nonridges.However,the application of fingerprint powders reduced the possibility to determine the immediacy of deposition.Conclusion:To conclude,both prior-deposition contaminated fingermarks and postdeposition contaminated fingermarks can be discriminated,providing information on the instance when a fingermark was left on a surface.
基金supported by the National Natural Science Foundation of China(21127007,21501009)the Scientific Research Foundation for the Returned Overseas Chinese Scholars(The 45th)the Fundamental Research Fund for the Central Universities(FRF-TP-15-019A1)
文摘A GC-MS method for analysis of amino acid compositions in fingermark residues was established.Sample was extracted by ethanol and derivatized with N-methyl-N-(trimethylsilyl)trifluoroacetamide for 6 min at 600 W of microwave.The recovery,repeatability,detection limit,and linear equation were investigated.The results indicated the method was rapid,sensitive and effective,and was very helpful for the development of fingerprint technique.
