Correlation of structural and mechanical properties for Al-Al2O3-SiC hybrid metal matrix composites

The aim of the present paper is to examine the outcome of Al2O3-SiC reinforcements on structural and mechanical behavior of Al matrix based hybrid composites. Al-Al2O3-SiC hybrid composite has been developed through stir casting with addition of ceramics i.e. Al2O3-SiC (2.5 wt.%, 5.0 wt.%, 7.5 wt.% and 10.0 wt.%) in relative and symmetrical proportion. The structural characteristics, i.e. phase, microstructure, EDS; physical property i.e. density and the mechanical properties, i.e. hardness, impact strength and tensile strength of fabricated specimens have been investigated. XRD represents the transitional phase formation among Al base material and Al2O3-SiC ceramic phases with inter-atomic bonding between them. SEM reveals that the Al2O3-SiC fragments has distributed symmetrically in Al matrix. EDS spectrum of various samples are in confirmation with the XRD results. Density of hybrid composite reduces with increase in weight percentage of ceramic reinforcements i.e. Al2O3-SiC because ceramic particle gains low density after preheating. Hardness of hybrid composites increases upto 5 wt.% variation of ceramic reinforcements i.e. Al2O3-SiC after that it decreases. Impact strength of hybrid composite has been increased with an increase in weight percentage of ceramic. Al-2.5 wt.% Al2O3-2.5 wt.% SiC shows maximum ultimate tensile strength. It is expected that the prepared hybrid composites will be useful for fastener studs.Scopu

Calcium Signaling Regulates Autophagy and Apoptosis

Calcium (Ca2+) functions as a second messenger that is critical in regulating fundamental physiological functions such as cell growth/development, cell survival, neuronal development and/or the maintenance of cellular functions. The coordination among various proteins/pumps/Ca2+ channels and Ca2+ storage in various organelles is critical in maintaining cytosolic Ca2+ levels that provide the spatial resolution needed for cellular homeostasis. An important regulatory aspect of Ca2+ homeostasis is a store operated Ca2+ entry (SOCE) mechanism that is activated by the depletion of Ca2+ from internal ER stores and has gained much attention for influencing functions in both excitable and non-excitable cells. Ca2+ has been shown to regulate opposing functions such as autophagy, that promote cell survival; on the other hand, Ca2+ also regulates programmed cell death processes such as apoptosis. The functional significance of the TRP/Orai channels has been elaborately studied; however, information on how they can modulate opposing functions and modulate function in excitable and non-excitable cells is limited. Importantly, perturbations in SOCE have been implicated in a spectrum of pathological neurodegenerative conditions. The critical role of autophagy machinery in the pathogenesis of neurodegenerative diseases such as Alzheimer’s, Parkinson’s, and Huntington’s diseases, would presumably unveil avenues for plausible therapeutic interventions for these diseases. We thus review the role of SOCE-regulated Ca2+ signaling in modulating these diverse functions in stem cell, immune regulation and neuromodulation

Corrosion, optimization and surface analysis of Fe-Al2O3-CeO2 metal matrix nanocomposites

In the present work, metal matrix nanocomposites are being prepared using Fe as base material reinforced with Al2O3 and doped with CeO2. Nanocomposite specimens were synthesized using powder metallurgy technique. Tafel Polarization, Corrosion Behavior and its optimization using Analysis of Variance (ANOVA) as well as Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) along with Phase and Microstructure of prepared samples have been investigated. It was observed that corrosion rate and corrosion current density was highest for pure Fe samples whereas 1.0% CeO2 doped Fe-Al2O3 metal matrix nanocomposite system showed the formation of nano amorphous layer on the specimen surface. Analysis of Variance shows that the different compositions of samples have changed outcome on corrosion behavior. Technique for Order of Preference by Similarity to Ideal Solution analysis shows ordered preference of sample as per the readings of corrosion rate.Scopu