IMECE2008-66778 FABRICATION AND CHAR ACTERIZATION OF BIO-INSPIRED STRUCTURAL COMPOSITES

ABSTRACT This paper presents the results of mechanical tests performed on bio-inspired structural composites. The details of synthesis process, loading configurations, testing conditions are discussed. Results of the tests clearly show the superiority of the biomimicked layered composites made from concrete and polymer, in terms of toughness over their monolithic counterparts. The implications of the results and their impact on construction technology will be elucidated. INTRODUCTION Tough structural materials are desirable for applications such as residential and commercial buildings. Tough structures will mitigate loss of life and property caused b y earthquakes, tornados and hurricanes. The main culprit in natural disasters is the presence of dynamic shear forces that demolish brittle brick and mortar buildings. One way to make tough materials is to mimic naturally tough structures such as nacre. Oyster and mother of pearl shells combine hardness of aragonite with the softness of natural polymers. The result is a tough structure with nominal strengths of 194-248 MPa [1] reported for 3-point bend tests performed on abalone and oyster

A 21-year-old Man with Delayed Puberty

Abstract Delayed puberty is defined clinically by the absence or incomplete development of secondary sexual characteristics bounded by an age at which 95 percent of children of that sex and culture have initiated sexual maturation. The upper 95th percentile in the United States for age for boys is 14 (an increase in testicular size being the first sign) and for girls is 12 (breast development being the first sign). Delayed puberty pathophysiologically is classified according to the circulating levels of the gonadotropins luteinizing hormone (LH) and follicle-stimulating hormone (FSH) in to two groups of high serum LH/FSH and low or normal serum LH/FSH concentrations which are related to primary hypogonadism and hypothalamic dysfunction respectively. Patient Presentation. A 21 year old boy presented with severe respiratory distress syndrome due to pneumonia and generalized edema. Laboratory studies showed pancytopenia which made clinicians work up for hematologic disorders, leading to bone marrow aspiration and biopsy which was consistent with megaloblastic anemia resulting from vit B12 deficiency. Another manifestation of this patient was delayed puberty which had been ignored over these years. Evaluation of delayed puberty revealed a low serum LH/FSH concentration. Accompaniment of delayed puberty resulting from hypothalamic origin with edema and hypoalbuminemia made clinicians work up for a malabsorption syndrome. Therefore upper endoscopy and colonoscopy were done and duodenal biopsies were consistent with celiac sprue. The unusual symptom of this patient was vit B12 deficiency which is rare in celiac disease. Conclusion. Neglected celiac sprue can be accompanied by vit B12 deficiency probably because of involvement of more distal parts of small intestine over the time