Matrix Hybridization in the Interlayer for Carbon Fiber Reinforced Composites

Polymeric composites have gone through a level of maturity beyond the laboratory stage with the development of the Boeing 787, the structure of which contains more than 50% composites. Nonetheless, a basic understanding of the material used in its primary structure has not been extensively investigated. For instance, micromechanical models are inadequate as they always assume an evenly distributed homogeneous matrix, without following classic lamination theory, which assumes constant stress through the laminate thickness. Our program now in its third year at the Polymeric Composites Laboratory in Seattle, supported by industry as well as government agencies, and in collaboration with several universities on a global scale, is developing such concepts for understanding and improving matrices in layered configurations. This effort focuses on the development of interlayer systems used as enablers to improve certain properties of the composite, such as fracture-toughness and crack-propagation inhibition. POLYM. COMPOS., 31:1965–1976, 2010.United States. Air Force Office of Scientific ResearchGloCal Network Corporatio

Development of a preclinical model of donation after circulatory determination of death for translational application

BACKGROUND: Extracorporeal membranous oxygenation is proposed for abdominal organ procurement from donation after circulatory determination of death (DCD). In France, the national Agency of Biomedicine supervises the procurement of kidneys from DCD, specifying the durations of tolerated warm and cold ischemia. However, no study has determined the optimal conditions of this technique. The aim of this work was to develop a preclinical model of DCD using abdominal normothermic oxygenated recirculation (ANOR). In short, our objectives are to characterize the mechanisms involved during ANOR and its impact on abdominal organs. METHODS: We used Large White pigs weighing between 45 and 55 kg. After 30 minutes of potassium-induced cardiac arrest, the descending thoracic aorta was clamped and ANOR set up between the inferior vena cava and the abdominal aorta for 4 hours. Hemodynamic, respiratory and biochemical parameters were collected. Blood gasometry and biochemistry analysis were performed during the ANOR procedure. RESULTS: Six ANOR procedures were performed. The surgical procedure is described and intraoperative parameters and biological data are presented. Pump flow rates were between 2.5 and 3 l/min. Hemodynamic, respiratory, and biochemical objectives were achieved under reproducible conditions. Interestingly, animals remained hemodynamically stable following the targeted protocol. Arterial pH was controlled, and natremia and renal function remained stable 4 hours after the procedure was started. Decreased hemoglobin and serum proteins levels, concomitant with increased lactate dehydrogenase activity, were observed as a consequence of the surgery. The serum potassium level was increased, owing to the extracorporeal circulation circuit. CONCLUSIONS: Our ANOR model is the closest to clinical conditions reported in the literature and will allow the study of the systemic and abdominal organ impact of this technique. The translational relevance of the pig will permit the determination of new biomarkers and protocols to improve DCD donor management

Blends of Epoxy Resin with polycarbonate and CTBN Rubber

The study described in this thesis examines how the toughenability of a difunctional epoxy resin cured with a diamine hardener is affected by the presence of a dissolved polycarbonate in the epoxy matrix, when that matrix is modified by CTBN rubber particles. The compatibility between the epoxy resin and four different polycarbonate types is investigated. Influence of polycarbonate content and of the type of polycarbonate upon the mechanical properties and morphology of polycarbonate or rubber-polycarbonate modified epoxy systems is considered. Toughenability of the epoxy matrix is found not to be improved by the presence of dissolved polycarbonate. Study of chemical interactions between polycarbonate and epoxy resin and polycarbonate and hardener shows a degradation of the polycarbonate by the epoxy resin and also by the diamine hardener. Failure of the polycarbonate to increase the toughenability of the epoxy matrix is considered to be related to this degradation. Toughness properties of polyethersulfone modified epoxy systems are also considered.MPhi

THE FREQUENCIES OF HAPTOGLOBIN TYPES IN FIVE POPULATIONS *

Haptoglobin types have been determined by starch gel electrophoresis of blood from five populations. The gene frequencies obtained for allele Hp 1 were as follows: American whites, 043; American Negroes, 0.59; African Negroes, 0.72; Apaches, 0.59; and Asiatic Indians, 0.18. In tribes of the Ivory Coast and Liberia, there was a suggestion of a cline which parallels that for haemoglobin S. Evidence is presented that the condition of ahaptoglobinemia is under genetic control but not by a gene allelic to the Hp 1 -Hp 2 series. The importance of the ahaptoglobinemic individuals for genetic studies and the possibility of selection in the maintenance of the genetic polymorphism are discussed. The authors wish to acknowledge the excellent assistance of Alojzia Sandor, who carried out the electrophoretic separations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66263/1/j.1469-1809.1958.tb01460.x.pd

A Case of Near Total Aortic Replacement in an Adolescent With Loeys-Dietz Syndrome

Loeys-Dietz syndrome is a recently described autosomal dominant disorder caused by mutations in the genes for transforming growth factor-beta receptor type 1 or 2 (TGF-ßR 1/2). The syndrome predisposes patients to aortic aneurysm and dissections, along with craniofacial and musculoskeletal abnormalities. Here we report the case of an adolescent who underwent serial near total aortic replacement, from the aortic valve to the descending aorta. Loeys-Dietz syndrome was confirmed in this case by the detection of a mutation in the TGF-ßR 2 gene

Comparative study between trimetazidine and ice slush hypothermia in protection against renal ischemia/reperfusion injury in a porcine model

PURPOSE: The aim of the study was to compare the effects of renal ice slush hypothermia and the use of trimetazidine in the protection against ischemia/reperfusion (I/R) injury. MATERIALS AND METHODS: Fifteen farm pigs were submitted to left kidney ischemia and right nephrectomy during the same procedure. Animals were divided into three groups. Group 1 was submitted to warm ischemia; Group 2 was submitted to cold ischemia with ice slush; and Group 3 received trimetazidine 20 mg one day and 4 hours before surgery. Ischemia time was 120 minutes in all three groups. Serum creatinine (SCr) and plasma iohexol clearance (CLioh) were measured before surgery and on postoperative days (PODs) 1,3,7, and 14. Semi-quantitative analyses of histological alterations were performed by a pathologist. A p value of < 0.05 was considered significant. RESULTS: All groups showed elevation of serum creatinine in the first week. Serum creatinine was higher in Group 3 in the first and third postoperative days (Mean Cr: 5.5 and 8.1 respectively). Group 2 showed a lower increase in creatinine and a lower decrease in iohexol clearance than the others. Renal function stabilized in the fourteenth POD in all three groups. Analyses of histological alterations did not reach statistical significance between groups. CONCLUSION: Trimetazidine did not show protection against renal I/R injury in comparison to warm ischemia or hypothermia in a porcine model submitted to 120 minutes of renal ischemia