Compressive Failure Behaviour of Novel Aramid Fibres

Since the development of the first truly synthetic fibres in the late nineteenth century, scientific efforts have lead to large variety of fibres ranging from fibres for textile applications to high performance fibres used as engineering materials. Examples of high performance fibres that are often used in engineering applications are aramid, glass and carbon fibres. Based on specific tensile properties polymer fibres such as aramids outperform glass and carbon fibres, but a major concern is, however, their behaviour under compressive loading. The work presented in this thesis describes a novel approach to increase the compressive strength of aramid (or PPTA) fibres and to characterise the compressive failure behaviour of these new fibres in more detail. The new concept is based on the addition of PPTA-compatible oligomers containing reactive end-groups. These newly designed oligomers can be considered to act as a molecular ‘glue’ to locally increase lateral cohesion and hence to increase the compressive properties without reducing the axial tensile properties.Fundamentals of Advanced MaterialsAerospace Engineerin

Elemental Imaging of Forensic Traces with Macro- and Micro-XRF

In this chapter, the use of macro- and micro-XRF imaging of forensic micro-traces is discussed. The opportunities of the unique elemental contrast offered by XRF will be demonstrated for important forensic trace evidence material including Gun Shot Residues or GSR, traces of human biological fluids such as blood, sperm, saliva and urine, and stains of personal care products and cosmetics. The possibility of detecting and visualizing concealed forensic stains in a virtually noninvasive manner by exploiting X-ray surface penetration will be illustrated. This chapter will conclude with an outlook on future trends with respect to the use of XRF imaging in forensic and crime scene investigations. The chapter has not been written as an extensive literature review as the aim of the authors is to provide the readers with new insights and ideas regarding the use of elemental imaging in forensic science

Radiographic Anatomy of the Pediatric Lisfranc Joint

Injuries to the Lisfranc joint in children and adolescents are rare. The incomplete ossification of the bones of the foot makes it difficult to detect injuries.The aim of this study was to determine age-specific radiographic measurements of the Lisfranc joint to provide guidance to the radiologist, emergency physicians, and surgeons to decrease misdiagnosis of Lisfranc injuries and improve detection. We retrospectively reviewed all foot radiographs without traumatic injury made between August 2014 and February 2015 in all patients younger than 18. The attendance list of the Emergency Department and Outpatient Clinic of a level-1 trauma center were used. Using a non-weight-bearing anteroposterior-view of the foot the distance between the base of metatarsal 1 and metatarsal 2 (MT1-MT2) and the distance between the medial cuneiform (MC) and the base of metatarsal 2 (MC-MT2) were measured. Median normal values were calculated per age. A total of 352 patients between the age of 0 and 18 years were screened for eligibility. Excluded were 109 patients because of anatomic abnormality, a fracture, inadequate radiograph, pain at the base of the first metatarsal, second metatarsal or MC, persisting pain at the Outpatient Clinic checkup or no follow-up. Included in the analysis were 243 patients. The distance between the base of MT1-MT2 was constant below 3 mm. Measurements for both MT1-MT2 and MC-MT2 distance approached adult values at the age of 6. Level II

Large area imaging of forensic evidence with MA-XRF

This study introduces the use of macroscopic X-ray fluorescence (MA-XRF) for the detection, classification and imaging of forensic traces over large object areas such as entire pieces of clothing and wall paneling. MA-XRF was sufficiently sensitive and selective to detect human biological traces like blood, semen, saliva, sweat and urine on fabric on the basis of Fe, Zn, K, Cl and Ca elemental signatures. With MA-XRF a new chemical contrast is introduced for human stain detection and this can provide a valuable alternative when the evidence item is challenging for conventional techniques. MA-XRF was also successfully employed for the chemical imaging and classification of gunshot residues (GSR). The full and non-invasive elemental mapping (Pb, Ba, Sr, K and Cl) of intact pieces of clothing allows for a detailed shooting incident reconstruction linking firearms and ammunition to point of impact and providing information on the shooting angle. In high resolution mode MA-XRF can even be used to provide information on the shooting order of different ammunition types. Finally, by using the surface penetration of X-rays we demonstrate that the lead signature of a bullet impact can be easily detected even if covered by multiple layers of wall paint or human blood.(OLD) MSE-