A lessons learned document for disputes in Florida Department of Transportation projects

The purpose of this research is to identify, analyze and evaluate the current Florida Department of Transportation (FDOT) reports in DRB database and develop a utilized, user friendly lessons learned document for FDOT and contractor. The analysis of the reports in the DRB database illustrated that, most common disputes in governmental transportation projects in Florida are due to unforeseen conditions. Over the course of this research, lessons were developed according to the recommendations made by DRB agents at the end of each case in 262 reports. Parties involved in a FDOT project can check this document to avoid recurrence of the negative outcomes and promote recurrence of the positive outcomes

The P2X1 receptor and platelet function

Extracellular nucleotides are ubiquitous signalling molecules, acting via the P2 class of surface receptors. Platelets express three P2 receptor subtypes, ADP-dependent P2Y1 and P2Y12 G-protein-coupled receptors and the ATP-gated P2X1 non-selective cation channel. Platelet P2X1 receptors can generate significant increases in intracellular Ca2+, leading to shape change, movement of secretory granules and low levels of αIIbβ3 integrin activation. P2X1 can also synergise with several other receptors to amplify signalling and functional events in the platelet. In particular, activation of P2X1 receptors by ATP released from dense granules amplifies the aggregation responses to low levels of the major agonists, collagen and thrombin. In vivo studies using transgenic murine models show that P2X1 receptors amplify localised thrombosis following damage of small arteries and arterioles and also contribute to thromboembolism induced by intravenous co-injection of collagen and adrenaline. In vitro, under flow conditions, P2X1 receptors contribute more to aggregate formation on collagen-coated surfaces as the shear rate is increased, which may explain their greater contribution to localised thrombosis in arterioles compared to venules within in vivo models. Since shear increases substantially near sites of stenosis, anti-P2X1 therapy represents a potential means of reducing thrombotic events at atherosclerotic plaques

Die Vasokonstriktion durch Ap5_{5}A und Ap6_{6}A in der isolierten perfundierten Rattenniere wird durch zwei unterschiedliche P2x_{2x}-Rezeptoren vermittelt

Die Effekte von Ap$_{5}$A und Ap$_{6}$A als Perfusionsdruckänderungen in der isolierten perfundierten Rattenniere werden in der Arbeit gemessen. Bei der Dauerperfusion mit diesen endogen vorkommenden Substanzen wurde sowohl eine initiale als auch eine permanente Vasokonstriktion festgestellt. Die Ergebnisse der Untersuchungen belegen, daß zwar die initiale, aber nicht die permanente Vasokonstriktion über den P$_{2X1}$ in der Rattenniere vermittelt wird

Modeling Precipitation Hardening and Yield Strength in Cast Al-Si-Mg-Mn Alloys

An integrated precipitation and strengthening model, incorporating the effect of precipitate morphology on precipitation kinetics and yield strength, is developed based on a modified Kampmann–Wagner numerical (KWN) framework with a precipitate shape factor. The optimized model was used to predict the yield strength of Al-Si-Mg-Mn casting alloys produced by vacuum high pressure die casting at various aged (T6) conditions. The solid solution strengthening contribution of Mn, which is a common alloying element to avoid die soldering, was included in the model to increase the prediction accuracy. The experimental results and simulations show good agreement and the model is capable of reliably predicting yield strength of aluminum die castings after T6 heat treatment, providing a useful tool to tailor heat treatment for a variety of applications

Determining the mechanical properties of sandwich composite materials for aviation applications

Flexure testing is one of the earliest means of evaluating stiffness and strength. This test is suggested to use in determination of the facing properties of the resistant materials (Kuenzi, 1951). This study was carried out to perform bending test of sandwich constructions suitable for ASTM D7249/D7249M standards and to determine facing material properties of sandwich constructions through evaluating the experimental data. Performing and conducting of the test: this study was carried out with collaboration of the Istanbul University and Turkish Airlines Technic under privacy in order to determine the facing properties of the sandwich constructions and it includes experimental and numerical methods. The study was carried out based on accepted standards