Experimental and theoretical studies into the release of blood droplets from weapon tips.

The formation and release under gravity of blood droplets from simulated weapon tips has been investigated experimentally and the results analysed and interpreted using established theoretical models for detached pendent drops. Droplets were produced from a series of conical nozzles, manufactured with a range of cone angles and including a set of un-bored conical tips, under conditions where the tip was either non-wetted or pre-wetted with blood. For the former, radius-limited case, detached droplet volumes were found to agree well with the predictions of both the pendent drop weight and drop shape models.

Use of Liquid Chromatography Quadrupole Time-of-Flight Mass Spectrometry and Metabonomic Profiling To Differentiate between Normally Slaughtered and Dead on Arrival Poultry Meat.

Metabonomic profiling techniques, with established quality control methods, have been used to detect subtle metabolic differences in tissue that could aid in the discovery of fraud within the food industry. Liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) was utilized to acquire metabolic profiles of muscle, heart, and liver tissue from normally slaughtered and dead on arrival chickens. A workflow including XCMS Online for data processing and robust confirmatory statistics was used in order to differentiate between the two sample types.

Age estimation of Calliphora (Diptera: Calliphoridae) larvae using cuticular hydrocarbon analysis and Artificial Neural Networks.

Cuticular hydrocarbons were extracted daily from the larvae of two closely related blowflies Calliphora vicina and Calliphora vomitoria (Diptera: Calliphoridae). The hydrocarbons were then analysed using Gas Chromatography-Mass Spectrometry (GC-MS), with the aim of observing changes within their chemical profiles in order to determine the larval age. The hydrocarbons were examined daily for each species from 1day old larvae until pupariation.

Identifying 1st instar larvae for three forensically important blowfly species using "fingerprint" cuticular hydrocarbon analysis.

Calliphoridae are known to be the most forensically important insects when it comes to establishing the minimum post mortem interval (PMImin) in criminal investigations. The first step in calculating the PMImin is to identify the larvae present to species level. Accurate identification which is conventionally carried out by morphological analysis is crucial because different insects have different life stage timings.

Experimental and theoretical studies of the spreading of bloodstains on painted surfaces.

The spreading of bloodstains on matt, vinyl silk and gloss painted surfaces, following both perpendicular and non-perpendicular impact, has been studied with a view to understanding whether surface-specific properties affect the size and shape of the final stain. In all cases the dimensions of the stains on the rougher, matt paint are up to 5% less than on the other painted surfaces though this difference decreases with impact velocity. Both the diameter of circular stains and the width of elliptical stains have been successfully modelled as a function of the perpendicular component of impact velocity vn using a modification of the energy conservation approach through the inclusion of a single, empirical constant characteristic of the surface itself.

Potential use of hydrocarbons for aging Lucilia sericata blowfly larvae to establish the postmortem interval.

Previous studies on Diptera have shown the potential for the use of cuticular hydrocarbons' analysis in the determination of larval age and hence the postmortem interval (PMI) for an associated cadaver. In this work, hydrocarbon compounds, extracted daily until pupation from the cuticle of the blowfly Lucilia sericata (Diptera: Calliphoridae), have been analyzed using gas chromatography-mass spectrometry (GC-MS). The results show distinguishing features within the hydrocarbon profile over the period of the larvae life cycle, with significant chemical changes occurring from the younger larvae to the postfeeding larvae.

Fundamental studies of bloodstain formation and characteristics.

A detailed understanding of blood droplet impact dynamics and stain formation is an essential prerequisite to the interpretation of both individual bloodstains and spatter patterns. The current literature on theoretical models for the spreading and splashing of liquid drops on surfaces relevant to the forensic context of bloodstain formation has been reviewed. These models have been evaluated for a paper substrate using experimental data obtained as function of droplet size, impact velocity and angle.

In situ luminescence spectroscopy with multivariate analysis for the discrimination of black ballpoint pen ink-lines on paper.

A novel approach to the non-destructive discrimination of black, ball-point pen ink-lines on paper, has been developed which uses a standard luminescence spectrometer coupled with multivariate statistical analysis. The application of Principal Component Analysis (PCA) to these data-sets, followed by linear regression of the loadings, not only facilitates separation of the ink luminescence from that of the paper, but also allows a direct comparison between two ink lines on documents. This data reduction means that such a comparison can be done on an effectively univariate basis whereby a straightforward statistical comparison is made between two numbers, each characteristic of an ink.

Classification and individualization of black ballpoint pen inks using principal component analysis of UV-vis absorption spectra.

The technique of principal component analysis has been applied to the UV-vis spectra of inks obtained from a wide range of black ballpoint pens available in the UK market. Both the pen ink and material extracted from the ink line on paper have been examined. Here, principal component analysis characterised each spectrum within a group through the numerical loadings attached to the first few principal components.