Chemically deposited magnesium hydroxide thin film

Here we report for the first time to the best of our knowledge the processing techniques, nucleation kinetics and the nanoindentation behaviour of a 1.5 mu m magnesium hydroxide thin film chemically deposited on a commercially available soda lime silica glass substrate at room temperature. The phase and microstructure of the films were analysed by X-ray diffraction, scanning electron microscopy, field emission scanning electron microscopy as well as transmission electron microscopy. An exponential nucleation kinetics was identified for the growth of the thin films. The nanomechanical properties, e. g. nanohardness and Young's modulus of the films were measured by the nanoindentation technique at ultralow loads of 50, 70 and 100 mu N. Finally, the nature of deformation of the thin film was analysed in terms of the energetics of the nanoindentation process and the microstructure

The Role of Intrinsically Unstructured Proteins in Neurodegenerative Diseases

The number and importance of intrinsically disordered proteins (IUP), known to be involved in various human disorders, are growing rapidly. To test for the generalized implications of intrinsic disorders in proteins involved in Neurodegenerative diseases, disorder prediction tools have been applied to three datasets comprising of proteins involved in Huntington Disease (HD), Parkinson's disease (PD), Alzheimer's disease (AD). Results show, in general, proteins in disease datasets possess significantly enhanced intrinsic unstructuredness. Most of these disordered proteins in the disease datasets are found to be involved in neuronal activities, signal transduction, apoptosis, intracellular traffic, cell differentiation etc. Also these proteins are found to have more number of interactors and hence as the proportion of disorderedness (i.e., the length of the unfolded stretch) increased, the size of the interaction network simultaneously increased. All these observations reflect that, “Moonlighting” i.e. the contextual acquisition of different structural conformations (transient), eventually may allow these disordered proteins to act as network “hubs” and thus they may have crucial influences in the pathogenecity of neurodegenerative diseases

Nanomechanical properties inside the scratch grooves of soda-lime-silica glass

Advanced applications of glass span the range from biomedical technology to special optical lenses to mobile phones and computers. Such advanced applications demand high-precision machining, which is like multiple single scratches occurring simultaneously on the glass surface. However, in spite of the wealth of literature on scratch deformation behavior of glass there is no significant information available on whether the nanomechanical properties are affected inside the scratch grooves. Therefore, nanoindentation experiments were deliberately conducted at a fixed load of 100 mN through the scratch grooves made at various applied normal loads (5-15 N) at a constant speed of 200 mu m s(-1) on polished soda-lime-silica (SLS) glass slides. The results showed that depending upon the applied normal load used to generate the scratch grooves, the nanohardness and Young's modulus inside the scratch grooves decreased by about similar to 30-60% from the corresponding data of the undamaged SLS glass due to the presence of sub-surface shear deformation and microcracking as observed by optical, scanning and field emission scanning electron microscopy. A model for microcracked brittle solids was utilized to explain these results

New observations on scratch deformations of soda lime silica glass

In spite of the wealth of literature, the role of the scratching speed in affecting the material removal mechanism in soda lime silica (SLS) glass is yet to be comprehensively understood. Here we report the surface and sub-surface deformation mechanisms of SLS glass scratched under three different normal loads of 5,10 and 15 N at various speeds in the range of 100-1000 mu m/s with a diamond indenter of similar to 200 mu m tip radius. The results show that at any given applied normal load, the width, depth, wear volume of the scratch grooves and wear rate of the SLS glass decreased with an inverse power law dependence on the applied scratching speed. The surface damage also reduced with the increase in scratching speed. A new, simple model was developed to explain these observations. The significant contributions of the time of contact, the tensile stress behind the indenter and the shear stress active just underneath the indenter in governing the material removal mechanisms of the SLS glass were discussed. (C) 2012 Elsevier B.V. All rights reserved

Growth of dip coated magnesium oxide nanoflower thin films

The present work reports the synthesis of dip coated MgO nanoflower thin films. The films are developed without employing any capping agent and catalyst. A simple chemical deposition technique is adopted for this purpose. The MgO nanoflower thin films are characterised by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, high resolution transmission electron microscopy and the related energy dispersive X-ray spectroscopy techniques. The results establish the phase purity and microstructural details of the MgO nanoflower thin films. These results are explained in terms of a proposed mechanism that suggests the growth process for the MgO nanoflower structures

Effect of scratching speed on deformation of soda-lime-silica glass

The grinding and polishing of a fundamentally brittle material like glass to an utmost precision level for ultra-sophisticated applications ranging from mobile devices to aerospace as well as space shuttle components to biomedical appliances pose a big challenge today. Looking simplistically, the grinding and polishing processes are basically material removal by multiple scratching at a given speed. Unfortunately however, the role of the scratching speed in affecting the material removal mechanism in soda-lime-silica (SLS) glass is yet to be comprehensively understood. Therefore, the present work explores the surface and subsurface deformation mechanisms of SLS glass scratched under a normal load of 5 N at various speeds in the range of 100-1000 mu m s(-1) with a diamond indenter of similar to 200 mu m tip radius. The results show important roles of the time of contact, the tensile stress behind the indenter and the shear stress just beneath the indenter in governing the material removal mechanisms of the SLS glass

Investigation on porous aluminosilicate soot layer for fabrication of specialty optical fiber using VPCD technique

The basic investigation of aluminosilicate porous core layer deposited using Vapour Phase Chelate Delivery (VPCD) technique is presented to optimize soot deposition parameters for subsequent processing to develop specialty optical fiber. Different soot deposition parameters namely vapour phase composition and porous core layer deposition temperature were studied in order to evaluate the change of porous soot layer morphology in terms of average pore size, pore size distribution, and chemical composition with the objective of selecting the optimized aluminosilicate soot structure. The field emission scanning electron microscope (FESEM) investigation reveals that the average pore size of the aluminosilicate soot strongly depends on the selected deposition tem-perature and its value increases from 0.7 mu m to 1.8 mu m for increasing deposition temperature from 1150 degrees C to 1250 degrees C. This average pore size of aluminosilicate soot however, increases significantly with addition of dopants like GeO2 and P2O5 and reaches the value of 3.9 mu m and 5.8 mu m respectively. It is also observed that the aluminium deposition efficiency in porous aluminosilicate soot layer depends on selected deposition temperature and for an increase of 20 degrees C, the deposition efficiency of Aluminium in the soot layer increases by-2.7%. It is also observed that aluminium incorporation efficiency using direct VPCD technique reaches a value of-90% compared to 72% if the process carried out by following deposition of porous soot layer. The observed result could help to achieve better control over the VPCD technique and could be extended to fabricate rare earth doped specialty optical fiber of specific design

Low strain rate compressive failure mechanism of coarse grain alumina

The present work reports the dynamic compressive strength (sigma(c)) of a dense (similar to 95%) coarse grain (similar to 20 mu m) alumina measured at 30 degrees C as a function of strain rates ((epsilon) over dot) ranging from 10(-5) to 5 x 10(-1) s(-1). The results showed a unique 40% enhancement of (sigma(c)) with the increase in ((epsilon) over dot). Extensive post mortem examination of fracture fragments obtained from the compressive failure tests by FESEM, TEM and HRTEM confirmed the formation of micro-cracks, shear bands, nanoscale cleavages and dislocations whose recurrence had increased with strain rate. Both shear induced microplasticity and nanoscale cleavages as well as dislocations had occurred concurrently yet independently during compressive fracture of coarse grain alumina even at very low strain rates. Based on these evidences a new compressive failure mechanism of alumina was proposed. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Catalyst free growth of MgO nanoribbons

Here, we report for the first time ever the catalyst free growth of magnesium oxide (MgO) nanoribbons on soda lime silica glass substrates by a green and inexpensive chemical route. The MgO nanoribbons were grown when the precursor magnesium hydroxide (Mg(OH)(2)) thin films were converted to MgO after 2 h of heat treatment in air at 450 degrees C. The MgO thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and the related energy dispersive X-ray spectroscopy (EDAX) techniques. Finally, a plausible mechanism is suggested for growth of the MgO nanoribbons. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved

Intelligently designed fly-ash based hybrid composites with very high hardness and Young's modulus

Currently, India generates annually about 112 million tones of fly ash (FA), as an industrial waste from thermal power plants. As part of the global journey to convert waste to wealth here we report the intelligent design based synthesis of FA based hybrid composites with spectacular improvement in Young's modulus and nanohardness. The novel design approach utilized alkali activation as well as simultaneous reinforcements of the porous FA matrix with a layered white china clay (WCC) and chopped E glass fiber. The developed materials were subsequently characterized by nanoindentation technique, pH measurement, alkali dissolution, FESEM, etc. techniques to evolve the structure-property correlation. The optimized design and optimal alkali activation lead to achievements of about 233% and 545% enhancements in Young's modulus and hardness, respectively. These results are rationalized in terms of chemical analysis, Si:Al ratio, presence of silicate network modifiers e.g., Na2O and CaO, microstructure, density, extent of polymerization due to alkali activation, processing condition and elastic recovery as well as the ratio of energy spent in elastic and plastic deformations during the nanoindentation processes. Finally, a schematic model is proposed to explain the experimental observations. (C) 2017 Elsevier Ltd. All rights reserved