Extensive facial damage caused by a blast injury arising from a 6 volt lead accumulator.
Low-voltage electrical injuries are relatively uncommon. Injury caused by flow of heavy current due to short-circuiting a low-voltage battery has not been described in the English literature. A 9-year-old boy connected two thin household electrical wires to the two terminals of a 6 volt (lead accumulator) battery and pressed the other two ends between his teeth. This resulted in a blast causing a compound comminuted fracture of the mandible and extensive tissue damage in the oral cavity. The low internal resistance of a lead accumulator (approximately 0.03 ohms) permits the flow of a heavy current (approximately 200 amps) when short-circuited. This instantaneously vaporises a minuscule portion of wire at approximately 2000 K resulting in a sudden rise of intraoral pressure to 30 kg cm-2 leading to tissue damage.
Tolerance of fondaparinux in a patient allergic to heparins and other glycosaminoglycans
We here report a 57-year-old Caucasian female patient with a history of DTH to several heparins, who was admitted as an inpatient for treatment of venous ulcers. In the light of her history, the glycosaminoglycan danaparoid (Orgaran) was chosen for prophylactic anticoagulation, which was necessary because of immobility and obesity. Two days after the initial injections, the patient developed erythematous plaques and disseminating papulovesicles at the injection sites (Fig. 1). Assuming DTH to danaparoid, anticoagulation was switched to the low molecular weight selective factor-Xa-inhibitor fondaparinux (Arixtra, Sanofi-Synthelabo, Berlin, Germany; 2.5mg subcutaneously per day), because recent reports document absence of in vitro cross-reactivity with antibodies to heparin-platelet factor 4; these may be associated with allergic heparin-induced skin reactions (2, 3). Fondaparinux was well tolerated throughout the treatment period of 2 weeks. A comprehensive series of skin allergy tests was initiated 6 weeks after clearance of the patient’s skin lesions using undiluted original drugs. Several heparins yielded positive i.c. test results at days 4–8 after injection of 0.1ml (undiluted drug, applied to the inner aspect of the lower left arm) with erythematous plaques developing at the injection sites (Table 1). A therapeutic dose of pentosan polysulfate was also injected subcutaneously, resulting in the formation of a similar lesion. In contrast, all skin tests with fondaparinux remained negative, and re-exposure 4 weeks after termination of the treatment was tolerated by the patient.
Damage initiation and propagation in composite shells subjected to impact
Abstract The paper investigates the impact-induced damage initiation and propagation for laminated composite shells under low-velocity impact. A three-dimensional eight-node non-conforming element is described to analyze interlaminar stress distribution, and progressive failure. The damage analysis is performed by using Tsai–Wu quadratic failure criterion, Tsai’s damage modes and an additional delamination formula at all Gaussian points. The damage modes considered are matrix cracking, fiber breakage and delamination. The progressive failure is expressed by reducing stiffness of the material at all failed Gaussian points. Special attention is centered on curved laminates. Impact energy threshold for the onset of damage and transient damage size are predicted for composite shells. The analyses of the flat and curved laminates are compared for discussing their different damage mechanism. In addition, the influence of the stacking sequence, the thickness and the radius of curvature on damage behavior of composite shells are studied.