Debra J. Carr

Fibers from three cultivars of New Zealand flax (Phormium tenax)

Botanists recognize only two kinds of New Zealand flax (Phormium tenax and Phormium colensoi), while Māori weavers recognise over fifty different cultivars that have specific end-uses. Selected properties of muka 4 (sclerenchyma fiber aggregates extracted from harakeke (P. tenax)) from three of these cultivars (Arawa, Tapamangu, Makaweroa) are examined. Māori consider these three cultivars to provide excellent fibers that are easy to process. Tapamangu and Arawa are similar in terms of muka length, linear density, tenacity, extension at maximum load, and maximum extension, and the ultimate fibers of these cultivars have similar dimensions (width, length). Muka from Makaweroa is longer, not as tough, but with a linear density similar to the other cultivars. The ultimate fiber length of Makaweroa is greater, but the width is similar to Tapamangu and Arawa. Muka from the keel is longer, of higher linear density, and tougher (similar tenacity, higher maximum extension) compared to margin muka. The side of the leaf from which muka is extracted does not affect the properties measured.

Standardizing a Pre-treatment Cleaning Procedure and Effects of Application on Apparel Fabrics

The objective of this work was to develop a pre-treatment (cleaning) procedure for a wide range of apparel fabrics and to determine whether differences observed in the properties of fabrics which had and had not been pre-treated were significant. Properties relevant to the manufacture and/or performance of apparel included mass per unit area, thickness, bending length, flex-ural rigidity, drape coefficient, air permeability, water vapor permeability, liquid absorptive capacity, drying time, ‘dry’ thermal resistance, ultra-violet transmission. Results for the same property on the same fabric measured when the fabrics had and had not been pre-treated generally differed significantly, confirming the importance of pre-treatment prior to measuring these properties, particularly when claiming in-use attributes of fabrics. A procedure for pre-treatment is recommended: six consecutive cleaning cycles following procedure 8A of British Standard EN ISO 6330: 2001 (i.e. not dried between cycles), and dried flat following procedure C of this standard.

Forensic evidence in apparel fabrics due to stab events.

Stab injuries and fatalities have been reported to be the most common crimes of violence in several countries, particularly in those where access to firearms is restricted [J.M. Taupin, F.-P. Adolf, J. Robertson, Examination of damage to textiles, in: J. Robertson, M. Grieve (Eds.), Forensic Examination of Fibres, CRC Press, United States of America, 1999, pp. 65-87; A.C. Hunt, R.J. Cowling, Murder by stabbing, Forensic Sci. Int. 52 (1991) 107-112; D.A. Rouse, Patterns of stab wounds: a six year study, Med. Sci. Law 34 (1994) 67-71]. Analysis of damaged apparel may provide important information about the cause of death and the events leading up to and after the victims final moments [M.T. Pailthorpe, N.A.G. Johnson, The private forensic scientist and the criminal justice system, in: D. Biles, J. Vernon (Eds.), Private Sector and Community Involvement in the Criminal Justice System: Conference Proceedings, vol. 23, Australian Institute of Criminology, Wellington, 1994, 231-240]. A high proportion of stab wounds occur in the chest and as this area is generally clothed many sharp force cases involve damage to fabrics [J.M. Taupin, F.-P. Adolf, J. Robertson, Examination of damage to textiles, in: J. Robertson, M. Grieve (Eds.), Forensic Examination of Fibres, CRC Press, United States of America, 1999, pp. 65-87; A.C. Hunt, R.J. Cowling, Murder by stabbing, Forensic Sci. Int. 52 (1991) 107-112; D.A. Rouse, Patterns of stab wounds: a six year study, Med. Sci. Law 34 (1994) 67-71]. The structural stabilisation and degradation of fabric due to laundering significantly alters fabric properties [S.E. Gore, R.M. Laing, C.A. Wilson, D.J. Carr, B.E. Niven, Standardizing a pre-treatment cleaning procedure and effects of application on apparel fabrics, Text. Res. J. 76 (2006) 455-464], yet the effect of such on severance morphology does not appear to have been investigated. In this work the effect of blade type (hunting knife, kitchen knife, screwdriver) on new and laundered apparel fabrics was investigated. Two approaches were used (i) a human participant trial, and (ii) guided drop testing (using an impact rig). Force-time plots from the human participant trials were matched to those from the impact rig. Information on severance morphology was obtained using visual analysis techniques. Blades could be differentiated and directionality estimated by observing differences in severance shape and size, the degree of fabric distortion, the position of severed yarn ends, loop snippets, curled yarns, planar array and the morphology of fractured fibres. Fabric construction had a visible effect on severance morphology. Pre-impact degradation via laundering hindered the ability to link fractured fibre ends to a source of damage by altering morphology and increasing the variability. The correlation between blade height and severance length was weak, attributed to elastic deformation and recovery. The impact rig was a valuable tool in the reconstruction of textile damage. Damage was consistent when inflicted using a human participant trial and the impact rig, although more variable in the former. The advantage of the impact rig lies in the ability to produce a severance typical of the blade in question, under controlled conditions, in a reproducible manner.

Structural Differences among Fibers from Six Cultivars of Harakeke (Phormium tenax, New Zealand flax)

The microscopic structure of muka (fiber aggregate extracted from harakeke) (observed using light microscopy and scanning electron microscopy) from six selected cultivars of harakeke varied, and this may explain the differences perceived by weavers, and that different end uses are preferred for various cultivars. The dimensions of ultimate fibers ranged from 10.1 μm (Takaiapu) to 12.8 μm (Paretaniwha) in average-transverse-width and 3735 μm (Takirikau) to 4751 μm (Makaweroa) in length. The cultivars prized for muka (e.g. Arawa, Makaweroa) had the longest and finest ultimate fibers. The transverse-section shapes of fiber aggregate bundles varied among the cultivars. Tapamangu and Takaiapu had fiber bundles that were more uniformly shaped than the other cultivars studied, and Takirikau had a high yield of fiber aggregate bundles. Paretaniwha differed from the other five cultivars studied having an average number of narrow, non-uniformly shaped fiber aggregate bundles per unit width.

Injury to recreational and professional cricket players: Circumstances, type and potential for intervention

This paper describes injury (circumstances and type) experienced by sub-populations at all levels of cricket and, where possible, the type of protective equipment used. The sample differs to that generally examined in the literature in that it is not restricted to evaluation of elite and professional players only. Over a 6-year period (2000-2005), 498 cases were identified. The average age of injury was 27 years and 86% of those injured were male. The population incidence rate was 2.3 per 100,000 per year, and participation incidence rate 39 per 100,000 per year. Over all age groups upper limb (36%) and lower limb (31%) were most commonly injured. Fracture was the main type of injury. Differences among age groups were identified. Children (<10 years) most commonly suffered head injury (contact with the bat); 10-19 year olds, head, upper and lower limb injury (in similar proportions) generally from contact with bat/ball; those over 20 years mainly had upper and lower limb injuries. Contact with the bat/ball was the dominant mechanism of injury for those under 50 years of age while overexertion, strenuous or repetitive movements, slips and falls were the mechanisms for those over 50. The large number of head injuries to children is of concern and both these, and the substantial number of injuries to the hand/phalanges (63% of all upper limb injuries), are important targets for injury prevention. The difference in injury patterns between children and adults is indicative of a need to develop, and use, different types of PPE at different skill/age levels.

Defining combat helmet coverage for protection against explosively propelled fragments

Introduction Prevention against head wounds from explosively propelled fragments is currently the Mark 7 general service combat helmet, although only limited evidence exists to define the coverage required for the helmet to adequately protect against such a threat. The Royal Centre for Defence Medicine was tasked by Defence Equipment and Support to provide a framework for determining the optimum coverage of future combat helmets in order to inform the VIRTUS procurement programme. Method A systematic review of the literature was undertaken to identify potential solutions to three components felt necessary to define the ideal helmet coverage required for protection against explosively propelled fragments. Results The brain and brainstem were identified as the structures requiring coverage by a helmet. No papers were identified that directly defined the margins of these structures to anatomical landmarks, nor how these could be related to helmet coverage. Conclusions We recommend relating the margins of the brain to three identifiable anatomical landmarks (nasion, external auditory meatus and superior nuchal line), which can in turn be related to the coverage provided by the helmet. Early assessments using an anatomical mannequin indicate that the current helmet covers the majority of the brain and brainstem from projectiles with a horizontal trajectory but not from ones that originate from the ground. Protection from projectiles with ground-originating trajectories is reduced by helmets with increased stand-off from the skin. Future helmet coverage assessments should use a finite element numerical modelling approach with representative material properties assigned to intracranial anatomical structures to enable differences in projectile trajectory and helmet coverage to be objectively compared.

Tensile Performance of Nonsterile Suture Monofilaments Affected by Test Conditions

Selection of a suture material typically depends on its tensile properties, but in the absence of an international standard test method, a comparison of properties is problem atic. A series of experiments is conducted to determine the tensile performance of non-knotted and knotted non-sterile suture monofilaments, and the effect of test conditions on this performance. Using the ear and cut loop technique, the factorial experiment includes three gauge lengths, three crosshead speeds, three non-sterile suture monofila ments, and five knot configurations. Each combination of variables is replicated five times. Different test conditions affect the ultimate strain and tenacity of both knotted and non-knotted monofilaments. Ultimate strain values are lower with increasing gauge length (when tested at the same crosshead speed) and crosshead speed (when tested at the same gauge length). All monofilaments are characterized by higher tenacity values with in creasing gauge length (at the same crosshead speed) and lower tenacity values with increasing crosshead speed (at the same gauge length). Load-extension curves and visual images of selected monofilament sutures are provided.

Protecting the extremities of military personnel: fragment protective performance of one- and two-layer ensembles

In order to provide protection from fragmenting ballistic threats, combat body armour contains multiple layers of fabric. The garment covers the torso, but may provide (removable) protection to the upper arms, neck and groin. Such garments are thick, stiff, impede movement and increase the thermophysiological loading of the dismounted soldier. Examination of wound locations from recent conflicts has suggested it would be advantageous to provide protection to the extremities. Current modular systems can be expanded with strap-on coverings to the arms and legs, but this further exacerbates the mass, mobility and thermal problems already observed. Soldiers already wear coverings on their arms and legs in the form of a combat uniform, and the provision of a hierarchical protection system incorporated in the existing uniform has been discussed. Not all areas of the body would be protected to the same level. In the current work, the fragment protective capabilities of one or two layers of commercially available para-aramid woven fabric. Specifically, 1.1 g chisel-nosed fragment simulating projectile V50 data were obtained. The aim was to establish whether the incorporation of such one or two layers of para-aramid woven fabric into current combat clothing could provide a level of fragment protection with only a minimal associated increase in stiffness, mass and thermal resistance. Post-failure analysis was conducted to investigate inter-layer interaction and failure mechanisms. This work suggests that the use of one- and two-layer para-aramid woven fabric layers incorporated into clothing could offer some protection against wounding to the extremities from fragments.

Standard Test Methods Adapted to Better Simulate Fabrics in Use

The objective was to adapt Standard test methods for determining properties of apparel fabrics so these properties are a better reflection of fabrics when used in end-products, while retaining a controlled environment and thus allowing fabric comparisons2. Test methods in which properties are compared when fabrics are dry and damp, and/ or in which they are in multiple-layered assemblies have been developed and applied to a range of fabrics.

Systematic investigation of drip stains on apparel fabrics: The effects of prior-laundering, fibre content and fabric structure on final stain appearance

Bloodstain pattern analysis is the investigation of blood deposited at crime scenes and the interpretation of that pattern. The surface that the blood gets deposited onto could distort the appearance of the bloodstain. The interaction of blood and apparel fabrics is in its infancy, but the interaction of liquids and apparel fabrics has been well documented and investigated in the field of textile science (e.g. the processes of wetting and wicking of fluids on fibres, yarns and fabrics). A systematic study on the final appearance of drip stains on torso apparel fabrics (100% cotton plain woven, 100% polyester plain woven, blend of polyester and cotton plain woven and 100% cotton single jersey knit) that had been laundered for six, 26 and 52 cycles prior to testing was investigated in the paper. The relationship between drop velocity (1.66±0.50m/s, 4.07±0.03m/s, 5.34±0.18m/s) and the stain characteristics (parent stain area, axes 1 and 2 and number of satellite stains) for each fabric was examined using analysis of variance. The experimental design and effect of storing blood were investigated on a reference sample, which indicated that the day (up to five days) at which the drops were generated did not affect the bloodstain. The effect of prior-laundering (six, 26 and 52 laundering cycles), fibre content (cotton vs. polyester vs. blend) and fabric structure (plain woven vs. single jersey knit) on the final appearance of the bloodstain were investigated. Distortion in the bloodstains produced on non-laundered fabrics indicated the importance of laundering fabrics to remove finishing treatments before conducting bloodstain experiments. For laundered fabrics, both the cotton fabrics and the blend had a circular to oval stain appearance, while the polyester fabric had a circular appearance with evidence of spread along the warp and weft yarns, which resulted in square-like stains at the lowest drop velocity. A significant (p<0.001) increase in the stain size on laundered blend fabric was identified. Bloodstain characteristics varied due to fibre content (p<0.001) and fabric structure (p<0.001). Blood on polyester fabric, after impact, primarily moved due to capillary force and wicking of the blood along the fibres/yarns, while for the cotton fabrics wicking was accompanied by movement of blood into the fibres/yarns. This study highlights the importance for forensic analysts of apparel evidence to consider the age, the fibre type and the fabric structure before interpreting bloodstain patterns.