The restoration of numerous aircraft structures is achievable with effective repair of welded joints. T-joints are often utilized in these structures to provide structural stability, keeping minimal body weight. Multi-pass friction stir welding (FSW) has proved to be useful for improving the quality of aluminium alloy welds employed in the aerospace sector. However, FSW of these alloys in T-configuration has not been sufficiently addressed yet. Even rarer is the discussion of efficacy of second FSW pass, with altered process parameters for improving the weld quality in T-joints. Hence, two commonly used aerospace grade aluminium alloys, namely, AA2024 and AA7075, were friction stir welded in T-configuration, varying three process parameters, i.e., tool rotational speed, welding speed and shoulder diameter. The effect of second FSW pass, performed at an optimum set of parameters, on kissing bond and tunnelling defect was studied in detail. A substantial reduction in the detrimental effect of these weld defects was discussed via tensile testing, micro-hardness and micro-structural observations.
Fifteen-millimeter-thick aluminum alloy AA6082-T651 extruded flats were friction-stir-welded by using three different types of tool pin profiles, i.e., (1) conical with only left-hand threads (CL), (2) conical with both left-hand and right-hand threads (CLR), and (3) conical cam-tri-flute with left-hand threads (CTFL) up to a height of 6 mm from the pin tip. The microstructures and the mechanical properties across the weld thickness were characterized. Tunneling defect was found at the weld-bottom for the CL tool pin profile and at the weld-top for the CLR pin profile. The reasons behind the formation of such defects have been analyzed and discussed. On the other hand, a defect-free joint was obtained with the CTFL pin profile. Tensile test samples were machined from top, middle, and bottom sections of the welds, and tensile strengths were measured for all the sections to determine the joint efficiencies. Scanning electron microscopy and energy-dispersive X-ray spectroscopy were employed to identify and study the morphology of the coarse phase particles present in the base material and in different regions of the welds. These results were correlated with the microhardness contours plotted across the weld cross section.
Inflammatory cytokines, cell adhesion molecules, and toll-like receptors (TLRs) play an important role in atherosclerosis. The aim of this study was to further evaluate the role of inflammatory cytokines, cell adhesion molecules, and toll-like receptors in atherosclerosis. Forty local breed domestic male rabbits were divided randomly into 4 groups, 10 rabbits each. Group I was the control group, group II received a high cholesterol diet, group III received the drug solvent dimethyl sulfoxide (DMSO), and group IV received Atorvastatin (3.5 mg/kg/day). Blood samples were collected at 0 times, 5 weeks, and at the end of 10 weeks. TLRs expression on monocyte was measured by flow cytometry, IL-10, IL-17, IL-1β, intracellular adhesion molecule (ICAM), and vascular cell adhesion molecule (VCAM) were measured by ELISA. In group II, a high cholesterol diet led to a statistically significant elevation of lipids profile (TC, TG, and LDL) at both 5 weeks and 10 weeks compared to the control. The expression of TLRs was also increased compared to the control (13.53±2.5 to 25.79±6.5). The intimal thickness increased from 103.46±13.85 to 248.43±11.11. IL-17 increased significantly from 3.4±0.4 to 7.7±1.00, and IL-1β increased from 1.04±0.19 to 9.66±1.4 (P 0.05) at 10 weeks. ICAM and VCAM increased from 1.7±0.16 to 8.2±0.74 and from 0.89±0.07 to 5.2±0.45, respectively. Atorvastatin significantly reduced TLRs at 10 weeks to 21.98±3.4 and intimal thickness to 191.6±15.59. IL-17, IL-1β, ICAM, and VCAM were significantly reduced by Atorvastatin. Cytokines, cellular adhesion molecules, and probably TLRs have a role in the pathogenesis of hyperlipidemia and atherosclerosis.
: Parkinson’s disease (PD) is one of the most common types of neurological disorder prevailing worldwide and is rapidly increasing in the elderly population across the globe. The cause of PD is still unknown, but a number of genetic as well as environmental factors contributing to the pathogenesis of Parkinson’s disease have been identified. The hallmark of PD includes dopamine deficiency (neurotransmitter imbalance) due to the gradual loss of dopaminergic nerves in the substantia nigra in the midbrain. Studying the mutation of associated genes is particularly informative in understanding the fundamental molecular and pathogenic changes in PD. Intracellular accumulation of misfolded or degraded protein due to mutated gene leads to the manifestation of mitochondrial dysfunction, oxidative stress followed by multifaceted patho-physiologic symptoms. Other studies include the appearance of motor and non-motor responses like resting tremor, muscle stiffness, slow movement and anxiety, anaemia, constipation, rapid eye movement and sleep behaviour disorder. Many bioactive natural compounds have shown positive pharmacological results in treating a number of extensive disease models of PD. Despite the availability of an end number of potent medicinal plants around the world, limited research has been done associated with various neurological disorders, including PD. The currently available dopamine-based drug treatments have several side effects; further, they are not effective enough to combat PD completely. Therefore, various plant-based compounds with medicinal benefits have grabbed lots of attention from researchers to deal with various life-threatening neurodegenerative disorders like PD. On the basis of literature available to date, here, we have discussed and addressed the molecular basis, current scenario, and the best possible treatment of PD for the future with minimal or no side-effects using various key bioactive compounds from natural origin/medicinal plants.
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