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The metallic damage to electrical conductors at fire scenes
Abstract
d) A Cold Case Justice Project to assist investigators to solve serious unsolved crime using DNA and other scientific and technical advancements (for instance, the Palmprint Database) e) A Mobile Forensic Laboratory Project to provide NSW Police with portable forensic science laboratory capability at remote crime scenes. All projects have been run under the Prince2 methodology since September 2007 and have been directed and managed by the Forensic Services Group, NSW Police Force (FSG), with support from partners, the Division of Analytical Laboratories, NSW Health (DAL). The current status of each project, most of which are now operational or almost operational, together with outcomes, successes, lessons learnt and recommendations. doi:10.1016/j.scijus.2009.11.017
Identification of Objects Thermogravimetry as a tool for the characterisation of polymeric items of forensic interest V. Causina, C. Maregaa, A. Marigoa, R. Neppallia, P. Carresib, S. Schiavonec a Università di Padova, Dipartimento di Scienze Chimiche, Padova, Italy b Carabinieri Laboratorio Analisi Sostanze Stupefacenti, Grosseto, Italy c Reparto Carabinieri Investigazioni Scientifiche, Messina, Italy Polymeric materials are ubiquitous in the modern world. It is therefore not a surprise that polymeric items are frequently of interest to the forensic examiner. Among the possible examples, there are plastic films used to pack illicit drugs, textile fibres, or plastic fragments in car accident sites. Plastic residues may be of interest in arson-related investigations. Latex gloves can be used by perpetrators of crimes and be discarded at or near the crime scene by less forensic-aware felons. For most kinds of items, a simple qualitative identification of the polymeric matrix is not sufficient. For example, in the case of plastic wraps of illicit drugs or of latex gloves, most of the commercial products on the market share the same main component (polyethylene for plastic bags, or latex in gloves) and therefore the need is felt for techniques that yield information on the formulation of the materials, i.e. on the additives or on the differences in the microstructural properties of the raw materials. In this communication the usefulness of thermogravimetry as a technique for yielding information on the formulation of polymeric items is discussed. In the thermogravimetric analysis (TGA) the mass variations as a function of temperature of a material are monitored. It is therefore possible to follow the degradation path of the sample, which is dependent on its formulation and on its microstructure. The discrimination potential (99.5% of the possible pairs of samples could be differentiated) of the technique on latex gloves will be shown, along with a case study in which the technique was applied. Examples of TGA analyses on different kinds of polymeric samples of possible forensic interest (i.e. tyres, foams and plastic pipings) will be shown. The effect of weathering, wearing out, or staining of items in the results of TGA analyses will be also discussed.
doi:10.1016/j.scijus.2009.11.018
Development of NITE-scapes for provenancing and authentication of food commodities J.A. Hoogewerff, H. Ueckermann, Trace Consortium www.trace.eu.org University of East Anglia, School of Chemistry, Norwich, United Kingdom In order to effectively support food security and combat food fraud it is essential to develop objective and independent tools to identify the geographical origin and movements of food through the supply chain.
29
Although the food industry has developed paper and electronic traceability systems, these systems are reliant on the operators in the supply chain and therefore by definition not independent. As plants and animals are integral parts of their natural or managed local ecosystem they will contain biogeochemical fingerprints that allow discrimination between those ecosystems by analytical means. The challenge for the scientific community is to investigate which markers deliver the most cost-effective and relevant geographical discrimination for each class of food products. In the last two decades small scale proof of concept research projects have demonstrated that foods from different geographical regions have both varying natural isotope ratio and trace element profiles (NITE). As these studies were very small scale, only involving maybe two or three source regions, there has been reasonable doubt that when using a larger number of source regions the apparent uniqueness of each region might break down. To investigate the consequences of such up-scaling the European Commission funded a large scale (9 M€) work-package on geographical profiling, within the (20 M€) TRACE project on traceability in 2005– 2009. The TRACE profiling investigation focused on 650 mineral waters from the whole of Europe and a detailed comparison of wheat, honey, olive oil, and lamb from 21 test regions with the regional soil and surface water composition and additional analysis of chicken and beef samples from different continents. From the first results of the TRACE project it is emerging that NITE profiling also works on large scales but that individualisation of production regions is probably not possible by NITE alone as indistinguishable climatological and geochemical conditions can occur at different, often faraway, geographical locations. Thus NITE-scapes can be very useful in answering compliance questions like, ‘Can this wheat come from a specific region?’ but not yet at finding the origin of an unknown batch, although it can indicate most likely (if known) areas and often even more valuably, exclude unlikely areas. In the presentation the achievements and remaining challenges will be presented.
doi:10.1016/j.scijus.2009.11.019
The metallic damage to electrical conductors at fire scenes N.J. Carey, N. Nic Daeid University of Strathclyde, Centre for Forensic Science, Dept of Pure and Applied Chemistry, Glasgow, United Kingdom
Fire investigators use conventional tools involving fire pattern analysis to determine a fire's area of origin; this can be erroneous with a fire scene that has been burning post-flashover for several minutes. The electrical installation may provide the fire investigator with useful data relating to the accurate location of the fire's area of origin. The damage often observed on electrical conductors at a fire scene is generally known arcing damage. This extremely localised melting of the copper metal often looks like molten beads and notches in various forms. Experiments were undertaken that involved the installation of electrical wiring into fully furnished compartments that were burnt, generally to flashover conditions. The main purpose of the research was to establish whether ‘arc mapping’ a technique to assist with determining the fire's area of origin is a reliable methodology. Another aim was to establish if the analysis of the post-fire conductors could determine whether the localised melting was due to electrical arcing damage or not. Various techniques were used to document and analyse the exhibits recovered from the experiments and these are described in detail.
doi:10.1016/j.scijus.2009.11.020
d) A Cold Case Justice Project to assist investigators to solve serious unsolved crime using DNA and other scientific and technical advancements (for instance, the Palmprint Database) e) A Mobile Forensic Laboratory Project to provide NSW Police with portable forensic science laboratory capability at remote crime scenes. All projects have been run under the Prince2 methodology since September 2007 and have been directed and managed by the Forensic Services Group, NSW Police Force (FSG), with support from partners, the Division of Analytical Laboratories, NSW Health (DAL). The current status of each project, most of which are now operational or almost operational, together with outcomes, successes, lessons learnt and recommendations. doi:10.1016/j.scijus.2009.11.017
Identification of Objects Thermogravimetry as a tool for the characterisation of polymeric items of forensic interest V. Causina, C. Maregaa, A. Marigoa, R. Neppallia, P. Carresib, S. Schiavonec a Università di Padova, Dipartimento di Scienze Chimiche, Padova, Italy b Carabinieri Laboratorio Analisi Sostanze Stupefacenti, Grosseto, Italy c Reparto Carabinieri Investigazioni Scientifiche, Messina, Italy Polymeric materials are ubiquitous in the modern world. It is therefore not a surprise that polymeric items are frequently of interest to the forensic examiner. Among the possible examples, there are plastic films used to pack illicit drugs, textile fibres, or plastic fragments in car accident sites. Plastic residues may be of interest in arson-related investigations. Latex gloves can be used by perpetrators of crimes and be discarded at or near the crime scene by less forensic-aware felons. For most kinds of items, a simple qualitative identification of the polymeric matrix is not sufficient. For example, in the case of plastic wraps of illicit drugs or of latex gloves, most of the commercial products on the market share the same main component (polyethylene for plastic bags, or latex in gloves) and therefore the need is felt for techniques that yield information on the formulation of the materials, i.e. on the additives or on the differences in the microstructural properties of the raw materials. In this communication the usefulness of thermogravimetry as a technique for yielding information on the formulation of polymeric items is discussed. In the thermogravimetric analysis (TGA) the mass variations as a function of temperature of a material are monitored. It is therefore possible to follow the degradation path of the sample, which is dependent on its formulation and on its microstructure. The discrimination potential (99.5% of the possible pairs of samples could be differentiated) of the technique on latex gloves will be shown, along with a case study in which the technique was applied. Examples of TGA analyses on different kinds of polymeric samples of possible forensic interest (i.e. tyres, foams and plastic pipings) will be shown. The effect of weathering, wearing out, or staining of items in the results of TGA analyses will be also discussed.
doi:10.1016/j.scijus.2009.11.018
Development of NITE-scapes for provenancing and authentication of food commodities J.A. Hoogewerff, H. Ueckermann, Trace Consortium www.trace.eu.org University of East Anglia, School of Chemistry, Norwich, United Kingdom In order to effectively support food security and combat food fraud it is essential to develop objective and independent tools to identify the geographical origin and movements of food through the supply chain.
29
Although the food industry has developed paper and electronic traceability systems, these systems are reliant on the operators in the supply chain and therefore by definition not independent. As plants and animals are integral parts of their natural or managed local ecosystem they will contain biogeochemical fingerprints that allow discrimination between those ecosystems by analytical means. The challenge for the scientific community is to investigate which markers deliver the most cost-effective and relevant geographical discrimination for each class of food products. In the last two decades small scale proof of concept research projects have demonstrated that foods from different geographical regions have both varying natural isotope ratio and trace element profiles (NITE). As these studies were very small scale, only involving maybe two or three source regions, there has been reasonable doubt that when using a larger number of source regions the apparent uniqueness of each region might break down. To investigate the consequences of such up-scaling the European Commission funded a large scale (9 M€) work-package on geographical profiling, within the (20 M€) TRACE project on traceability in 2005– 2009. The TRACE profiling investigation focused on 650 mineral waters from the whole of Europe and a detailed comparison of wheat, honey, olive oil, and lamb from 21 test regions with the regional soil and surface water composition and additional analysis of chicken and beef samples from different continents. From the first results of the TRACE project it is emerging that NITE profiling also works on large scales but that individualisation of production regions is probably not possible by NITE alone as indistinguishable climatological and geochemical conditions can occur at different, often faraway, geographical locations. Thus NITE-scapes can be very useful in answering compliance questions like, ‘Can this wheat come from a specific region?’ but not yet at finding the origin of an unknown batch, although it can indicate most likely (if known) areas and often even more valuably, exclude unlikely areas. In the presentation the achievements and remaining challenges will be presented.
doi:10.1016/j.scijus.2009.11.019
The metallic damage to electrical conductors at fire scenes N.J. Carey, N. Nic Daeid University of Strathclyde, Centre for Forensic Science, Dept of Pure and Applied Chemistry, Glasgow, United Kingdom
Fire investigators use conventional tools involving fire pattern analysis to determine a fire's area of origin; this can be erroneous with a fire scene that has been burning post-flashover for several minutes. The electrical installation may provide the fire investigator with useful data relating to the accurate location of the fire's area of origin. The damage often observed on electrical conductors at a fire scene is generally known arcing damage. This extremely localised melting of the copper metal often looks like molten beads and notches in various forms. Experiments were undertaken that involved the installation of electrical wiring into fully furnished compartments that were burnt, generally to flashover conditions. The main purpose of the research was to establish whether ‘arc mapping’ a technique to assist with determining the fire's area of origin is a reliable methodology. Another aim was to establish if the analysis of the post-fire conductors could determine whether the localised melting was due to electrical arcing damage or not. Various techniques were used to document and analyse the exhibits recovered from the experiments and these are described in detail.
doi:10.1016/j.scijus.2009.11.020