An overview of burst, buckling, durability and corrosion analysis of lightweight FRP composite pipes and their applicability

© 2019 Elsevier Ltd. All rights reserved.The main aim of this review article was to address the performance of filament wound fibre reinforced polymer (FRP) composite pipes and their critical properties, such as burst, buckling, durability and corrosion. The importance of process parameters concerning merits and demerits of the manufacturing methods was discussed for the better-quality performance. Burst analysis revealed that the winding angle of ±55° was observed to be optimum with minimum failure mechanisms, such as matrix cracking, whitening, leakage and fracture. The reduction of buckling effect was reported in case of lower hoop stress value in the hoop to axial stress ratio against axial, compression and torsion. A significant improvement in energy absorption was observed in the hybrid composite pipes with the effect of thermal treatment. However, the varying winding angle in FRP pipe fabrication was reported as an influencing factor affecting all the aforementioned properties. Almost 90% of the reviewed studies was done using E-glass/epoxy materials for the composite pipe production. By overcoming associated limitations, such as replacing synthetic materials, designing new material combinations and cost-benefit analysis, the production cost of the lightweight FRP composite pipes can be decreased for the real-time applications.Peer reviewe

Oxidative stress affects synaptosomal gamma-aminobutyric acid and glutamate transport in diabetic rats: the role of insulin

Evidence suggests that oxidative stress is involved in the pathophysiology of diabetic complications and that insulin has a neuroprotective role in oxidative stress conditions. In this study, we evaluated the in vitro effect of insulin in the susceptibility to oxidative stress and in the transport of the amino acid neurotransmitters γ-aminobutyric acid (GABA) and glutamate in a synaptosomal fraction isolated from male type 2 diabetic Goto-Kakizaki (GK) rat brain cortex. The ascorbate/Fe2+-induced increase in thiobarbituric acid reactive substances (TBARSs) was similar in Wistar and GK rats and was not reverted by insulin (1 μmol/l), suggesting that other mechanisms, rather than a direct effect in membrane lipid peroxidation, may mediate insulin neuroprotection. Diabetes did not affect GABA and glutamate transport, despite the significant decrease in membrane potential and ATP/ADP ratio, and insulin increased the uptake of both GABA and glutamate in GK rats. Upon oxidation, there was a decrease in the uptake of both neurotransmitters and an increase in extrasynaptosomal glutamate levels and in ATP/ADP ratio in GK rats. Insulin treatment reverted the ascorbate/Fe2+-induced decrease in GABA accumulation, with a decrease in extrasynaptosomal GABA. These results suggest that insulin modulates synaptosomal GABA and/or glutamate transport, thus having a neuroprotective role under oxidizing and/or diabetic condition