Reagents for infrared chemical imaging of fingerprints on difficult surfaces

University of Technology Sydney. Faculty of Science.Fingerprints continue to be an important form of forensic evidence for individual identification. A number of techniques are currently available for the detection and enhancement of invisible or latent fingerprints. While these techniques perform well on many surfaces, there are a number of surfaces that pose problems. On such surfaces, Fourier transform infrared (FTIR) chemical imaging can provide superior results. FTIR chemical imaging involves the simultaneous collection of thousands of mid-infrared spectra across a sample using a focal plane array (FPA) detector. This allows for the collection of chemically specific spectral data while maintaining spatial information. Images can then be generated based on spectral / chemical contrast between components within a sample. A key aim of this project was to further investigate the use of FTIR chemical imaging for the detection and enhancement of latent (untreated) and developed (treated) fingerprints on a number of ‘difficult’ surfaces. During the initial development of an infrared chemical imaging technique for fingerprints, an un-optimised set of image collection parameters was used. Using these settings, the collection of an entire fingerprint image was time consuming (often several hours or days). A systematic method for the optimisation of the image collection parameters has been developed. This method allows the optimisation of parameters such as spectral resolution, number of co-added scans, spectral range, pixel aggregation and image formation parameters in order to minimise image collection time and file size while maintaining the quality of the fingerprint image produced. A commonly-used fingerprint detection technique for latent fingerprints on non-porous or semi-porous surfaces involves fuming samples with monomeric ethyl 2-cyanoacrylate (superglue). This reagent leaves a white residue (polymeric cyanoacrylate) on the ridges of latent fingerprints, rendering them visible under white light. On some surfaces, such as polymer banknotes, however, the contrast between cyanoacrylate-developed fingerprints and the background is poor. FTIR chemical imaging of cyanoacrylate fumed fingerprints on polymer banknotes and other difficult surfaces has been shown to provide better results than optical techniques alone. During this project, further investigations into the use of FTIR chemical imaging for latent fingerprints treated with commercial cyanoacrylate monomer on a range of difficult surfaces were conducted. While excellent results were obtained on many samples, the need for novel cyanoacrylates containing infrared absorbance in specific parts of the spectrum was identified. A major focus of this project has been the identification, synthesis and characterisation of modified cyanoacrylates which may be used as reagents for FTIR chemical imaging of fingerprints. Monomers that contained particular functional groups that show vibrational modes in the range from 2500 – 1800 cm-1 were sought. This region typically contains very few vibrational bands and therefore a reagent that could be used to give fingerprints absorptions in this range is desirable. This would provide the necessary contrast between the ridge details of the treated fingerprint and the background on which it may be located. In total four novel cyanoacrylates were prepared. These included 2-cyanoethyl 2- cyanoacrylate (2-CECA), 1-cyanoethyl 2-cyanoacrylate (1-CECA), trideuteromethyl 2- cyanoacrylate (MCA-d3) and pentadeuteroethyl 2-cyanoacrylate (ECA-d5). Each of the four novel monomers was tested a reagent for the detection and enhancement of latent fingerprints on a number of surfaces via FTIR chemical imaging. The 2-CECA monomer was found to be less volatile than conventional cyanoacrylate and thermally decomposed at the temperatures required to vaporise it. Treating latent fingerprints with this monomer at a reduced pressure yielded better results on reflective surfaces. On less reflective surfaces, such as polymer banknotes, however, the nitrile band of 2-CECA was almost undetectable and therefore could not be used for imaging the treated prints. Fingerprints treated with the deuterated monomers (MCA-d3 and ECA-d5) showed characteristic bands in the region from 2300 – 1900 cm-1 owing to C–D stretching vibrations. Once again, however, the relatively low intensity of these bands meant that they were only detected from prints on reflective surfaces. The monomer that produced the best results was 1-CECA. Surprisingly the contrast between the ridge detail and the background, was not generated by the nitrile band at 2250 cm-1 as anticipated. Instead it appears that the absorption band for the carbonyl group in poly-1- CECA is sufficiently resolved from any absorption within this region from the background surface (such as polymer banknotes) to provide good contrast images of the treated fingerprint. High quality fingerprint images were obtained of prints treated with 1-CECA on all difficult surfaces tested including white opaque acrylic sheets, fluorescent acrylic sheets and all areas of polymer banknotes including areas containing raised intaglio printing

Development and validation of a presumptive colour spot test method for the detection of piperazine analogues in seized illicit materials

The increasingly large quantities of potentially illicit samples received for confirmatory analysis highlights the importance and demand for preliminary testing procedures that are simple, rapid, selective, inexpensive and able to be used in the field. Colour testing fulfils the aforementioned requirements and is a technique frequently employed to achieve presumptive identification. Piperazine analogues (often marketed as 'legal ecstasy') are a group of psychoactive substances that have recently become established on the illicit drug market and are not effectively discriminated or identified by current colour testing methods. Herein, we report on the development and validation of a chemical spot test for piperazine analogues present in unknown seized materials using the spectrophotometric reagent, sodium 1,2-naphthoquinone-4-sulphonate (NQS). Primary testing revealed that NQS reacts almost instantly to form an intense, bright orange-red coloured complex with the representative piperazine 1-benzylpiperazine (BZP) at room temperature. The results of the test, assessed by colour development, were evaluated visually and variables affecting the coloured reaction were optimised. The colour test method was validated to meet requirements for use in preliminary screening, providing qualitative and reliable presumptive test results. Validation studies show that the characteristic colour change is unique to the piperazine class at room temperature, and is unaffected by the presence of common cutting agents, i.e. glucose and caffeine, in test samples of 5% purity, and other drugs such as N-methyl-3,4-methylenedioxyamphetamine (MDMA). The NQS reagent stability was found to be limited to storage in a refrigerated environment for no more than one week before results were affected. The operational limit of detection was found to be 40 μg. © 2013 The Royal Society of Chemistry

Thermal development of latent fingermarks on porous surfaces-Further observations and refinements

In a further study of the thermal development of fingermarks on paper and similar surfaces, it is demonstrated that direct contact heating of the substrate using coated or ceramic surfaces at temperatures in excess of 230 °C produces results superior to those obtained using hot air. Fingermarks can also be developed in this way on other cellulose-based substrates such as wood and cotton fabric, though ridge detail is difficult to obtain in the latter case. Fluorescence spectroscopy indicates that the phenomena observed during the thermal development of fingermarks can be reproduced simply by heating untreated white copy paper or filter paper, or these papers treated with solutions of sodium chloride or alanine. There is no evidence to suggest that the observed fluorescence of fingermarks heated on paper is due to a reaction of fingermark constituents on or with the paper. Instead, we maintain that the ridge contrast observed first as fluorescence, and later as brown charring, is simply an acceleration of the thermal degradation of the paper. Thermal degradation of cellulose, a major constituent of paper and wood, is known to give rise to a fluorescent product if sufficient oxygen is available [1-5]. However, the absence of atmospheric oxygen has only a slight effect on the thermal development of fingermarks, indicating that there is sufficient oxygen already present in paper to allow the formation of the fluorescent and charred products. In a depletion study comparing thermal development of fingermarks on paper with development using ninhydrin, the thermal technique was found to be as sensitive as ninhydrin for six out of seven donors. When thermal development was used in sequence with ninhydrin and DFO, it was found that only fingermarks that had been developed to the fluorescent stage (a few seconds of heating) could subsequently be developed with the other reagents. In the reverse sequence, no useful further development was noted for fingermarks that were treated thermally after having been developed with ninhydrin or DFO. Aged fingermarks, including marks from 1-year-old university examination papers were successfully developed using the thermal technique. © 2010 Elsevier Ireland Ltd

Forensic intelligence framework. Part II: study of the main generic building blocks and challenges through the examples of illicit drugs and false identity documents monitoring

The development of forensic intelligence relies on the expression of suitable models that better represent the contribution of forensic intelligence in relation to the criminal justice system, policing and security. Such models assist in comparing and evaluating methods and new technologies, provide transparency and foster the development of new applications. Interestingly, strong similarities between two separate projects focusing on specific forensic science areas were recently observed. These observations have led to the induction of a general model (Part I) that could guide the use of any forensic science case data in an intelligence perspective. The present article builds upon this general approach by focusing on decisional and organisational issues. The article investigates the comparison process and evaluation system that lay at the heart of the forensic intelligence framework, advocating scientific decision criteria and a structured but flexible and dynamic architecture. These building blocks are crucial and clearly lay within the expertise of forensic scientists. However, it is only part of the problem. Forensic intelligence includes other blocks with their respective interactions, decision points and tensions (e.g. regarding how to guide detection and how to integrate forensic information with other information). Formalising these blocks identifies many questions and potential answers. Addressing these questions is essential for the progress of the discipline. Such a process requires clarifying the role and place of the forensic scientist within the whole process and their relationship to other stakeholders

Biometrics in forensic science: challenges, lessons and new technologies

Biometrics has historically found its natural mate in Forensics. The first applications found in the literature and over cited so many times, are related to biometric measurements for the identification of multiple offenders from some of their biometric and anthropometric characteristics (tenprint cards) and individualization of offender from traces found on crime-scenes (e.g. fingermarks, earmarks, bitemarks, DNA). From sir Francis Galton, to the introduction of AFIS systems in the scientific laboratories of police departments, Biometrics and Forensics have been "dating" with alternate results and outcomes. As a matter of facts there are many technologies developed under the "Biometrics umbrella" which may be optimised to better impact several Forensic scenarios and criminal investigations. At the same time, there is an almost endless list of open problems and processes in Forensics which may benefit from the introduction of tailored Biometric technologies. Joining the two disciplines, on a proper scientific ground, may only result in the success for both fields, as well as a tangible benefit for the society. A number of Forensic processes may involve Biometric-related technologies, among them: Evidence evaluation, Forensic investigation, Forensic Intelligence, Surveillance, Forensic ID management and Verification.\ud The COST Action IC1106 funded by the European Commission, is trying to better understand how Biometric and Forensics synergies can be exploited within a pan-European scientific alliance which extends its scope to partners from USA, China and Australia.\ud Several results have been already accomplished pursuing research in this direction. Notably the studies in 2D and 3D face recognition have been gradually applied to the forensic investigation process. In this paper a few solutions will be presented to match 3D face shapes along with some experimental results

Near infrared hyperspectral imaging for forensic analysis of document forgery

[EN] Hyperspectral images in the near infrared range (HSI-NIR) were evaluated as a nondestructive method to detect fraud in documents. Three different types of typical forgeries were simulated by (a) obliterating text, (b) adding text and (c) approaching the crossing lines problem. The simulated samples were imaged in the range of 928 2524 nm with spectral and spatial resolutions of 6.3 nm and 10 mm, respectively. After data pre-processing, different chemometric techniques were evaluated for each type of forgery. Principal component analysis (PCA) was performed to elucidate the first two types of adulteration, (a) and (b). Moreover, Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) was used in an attempt to improve the results of the type (a) obliteration and type (b) adding text problems. Finally, MCR-ALS and Partial Least Squares Discriminant Analysis (PLS-DA), employed as a variable selection tool, were used to study the type (c) forgeries, i.e. crossing lines problem. Type (a) forgeries (obliterating text) were successfully identified in 43% of the samples using both the chemometric methods (PCA and MCR-ALS). Type (b) forgeries (adding text) were successfully identified in 82% of the samples using both the methods (PCA and MCR-ALS). Finally, type (c) forgeries (crossing lines) were successfully identified in 85% of the samples. The results demonstrate the potential of HSI-NIR associated with chemometric tools to support document forgery identificationINCTAA (Processes no. : CNPq 573894/2008-6; FAPESP 2008/57808-1), NUQAAPE, FACEPE, CNPq, CAPES, Spanish Ministry of Science and Innovation MICINN (grant DPI2011-28112-C04-02).Silva, CS.; Pimentel, MF.; Honorato, RS.; Pasquini, C.; Prats Montalbán, JM.; Ferrer Riquelme, AJ. (2014). Near infrared hyperspectral imaging for forensic analysis of document forgery. Analyst. 139(20):5176-5184. https://doi.org/10.1039/C4AN00961DS517651841392

Multiple Changes in Peptide and Lipid Expression Associated with Regeneration in the Nervous System of the Medicinal Leech

peer reviewe

Experimental Measurement of Local Burning Velocity Within a Rotating Flow

The final publication is available at link.springer.com.The work presented in this paper details the implementation of a new technique for the measurement of local burning velocity using asynchronous particle image velocimetry. This technique uses the local flow velocity ahead of the flame front to measure the movement of the flame by the surrounding fluid. This information is then used to quantify the local burning velocity by taking into account the translation of the flame via convection. In this paper the developed technique is used to study the interaction between a flame front and a single toroidal vortex for the case of premixed stoichiometric methane and air combustion. This data is then used to assess the impact of vortex structure on flame propagation rates. The burning velocity data demonstrates that there is a significant enhancement to the rate of flame propagation where the flame directly interacts with the rotating vortex. The increases found were significantly higher than expected but are supported by burning velocities [22-24] found in turbulent flames of the same mixture composition. Away from this interaction with the main vortex core, the flame exhibits propagation rates around the value recorded in literature for unperturbed laminar combustion [18-21]

Color spot test as a presumptive tool for the rapid detection of synthetic cathinones

© 2018 Journal of Visualized Experiments. Synthetic cathinones are a large class of new psychoactive substances (NPS) that are increasingly prevalent in drug seizures made by law enforcement and other border protection agencies globally. Color testing is a presumptive identification technique indicating the presence or absence of a particular drug class using rapid and uncomplicated chemical methods. Owing to their relatively recent emergence, a color test for the specific identification of synthetic cathinones is not currently available. In this study, we introduce a protocol for the presumptive identification of synthetic cathinones, employing three aqueous reagent solutions: copper(II) nitrate, 2,9-dimethyl-1,10-phenanthroline (neocuproine) and sodium acetate. Small pin-head sized amounts (approximately 0.1-0.2 mg) of the suspected drugs are added to the wells of a porcelain spot plate, and each reagent is then added dropwise sequentially before heating on a hotplate. A color change from very light blue to yellow-orange after 10 min indicates the likely presence of synthetic cathinones. The highly stable and specific test reagent has the potential for use in the presumptive screening of unknown samples for synthetic cathinones in a forensic laboratory. However, the nuisance of an added heating step for the color change result limits the test to laboratory application and decreases the likelihood of an easy translation to field testing