Experimental Investigations on Microstructure,Properties and Workability Behavior of Zinc Oxide Reinforced Al–Si–Mg Matrix Composites

Silicon - Al-Si based alloy matrix composites are now broadly utilized by the industrial sectors like automobile, structural, aerospace and more practical industrial applications due to its...     

Experimental and Simulation Analysis of Silkworm Cocoon Waste Fiber Reinforced Concrete Using FNN with EMBA Optimization

Silicon - Due to the expansion and modernization of the human population, the construction area has gradually developed. As innovations develop, a large portion of the fiber waste is thermosetting...     

Performance Evaluation of Stacked Gate Oxide/High K Spacers Based Gate All Around Device Architectures at 10 nm Technology Node

Silicon - In this paper, we have done performance evaluation of different Gate All Around (GAA) FET device structures using gate-oxide stacking and spacers of different materials including dual and...     

Preparation and characterization of poly(vinyl alcohol) cryogel‐silver nanocomposites and evaluation of blood compatibility,cytotoxicity, and antimicrobial behaviors

In this investigation, cryogels composed of poly(vinyl alcohol) (PVA) were prepared by repeated freeze‐thaw method. The prepared cryogels served as templates for producing highly stable and uniformly distributed silver nanoparticles via in situ reduction of silver nitrate (AgNO₃) using alkaline formaldehyde solution as reducing agent. The structure of the PVA/Ag cryogel nanocomposites was characterized by a Fourier transform infrared and Raman spectroscopy. The morphologies of pure PVA cryogels and PVA/Ag nanocomposites were observed by a scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. The SEM analysis suggested that cryogels show a well defined porous morphology whereas TEM micrographs revealed the presence of nearly spherical and well separated Ag nanoparticles with diameter about 100 nm. XRD results showed all relevant Bragg's reflections for crystal structure of silver nanoparticles. The amount of silver in cryogel nanocomposites and thermal stability were determined by inductively coupled plasma atomic emission spectrometry (ICP‐AES) and thermogravimetric analysis measurements. Mechanical properties of nanocomposites were observed in terms of tensile strength. The antibacterial studies of the synthesized nanosilver containing cryogels showed good antibacterial activity against both gram‐negative and gram‐positive bacteria. The prepared PVA/Ag nanocomposites were also investigated for swelling and deswelling behaviors. The results reveal that both the swelling and deswelling process depends on the chemical composition of the cryogel silver nanocomposites, number of freeze‐Thaw cycles and pH and temperature of the swelling medium. The biocompatibility of the prepared nanocomposites was judged by in vitro methods of percent hemolysis and protein (BSA) adsorption. POLYM. COMPOS., 36:1983–1997, 2015. © 2014 Society of Plastics Engineer     

Crystalline selenite substituted carbonated hydroxyapatite nanorods: Synthesis,characterization, evaluation of bioactivity and cytotoxicity

Synthesis of pure and selenite substituted hydroxyapatites (HAP and Se‐HAP with 0.02–0.10 Se) by sol–gel method and evaluation of their morphological features, nature of functional groups, phase purity, in vitro bioactivity and cytotoxicity are addressed. Spectral studies confirm the incorporation of selenite into the HAP lattice, accompanied by an increase in CO₃^2? content to maintain the charge imbalance following replacement of P⁵⁺ with Se⁴⁺, thus making the formation of selenite substituted carbonated HAP. Selenite substitution in the HAP lattice has led to a higher crystallinity and increased the crystallite size. The morphology of HAP is changed from sphere to rod‐like structure upon substitution by selenite and the size of the rod is increased with an increase in the selenite content. Among the Se‐HAPs, a better in vitro bioactivity and cell viability are observed for 0.02 Se‐HAP and 0.04 Se‐HAP while the trend is reversed when the extent of selenite substitution becomes higher.     

Biodegradable poly(ester‐ether)s: ring‐opening polymerization of D,L‐3‐methyl‐1,4‐dioxan‐2‐one using various initiator systems

The synthesis and detailed characterization of racemic 3‐methyl‐1,4‐dioxan‐2‐one (3‐MeDX) are reported. The bulk ring‐opening polymerization of 3‐MeDX, to yield a poly(ester‐ether) meant for biomedical applications, in the presence of various initiators such as tin(II) octanoate, tin(II) octanoate/n‐butyl alcohol, aluminium tris‐isopropoxide and an aluminium Schiff base complex (HAPENAlOⁱPr) under varying experimental conditions is here detailed for the first time. Polymerization kinetics were investigated and compared with those of 1,4‐dioxan‐2‐one. The studies reveal that the rate of polymerization of 3‐MeDX is less than that of 1,4‐dioxan‐2‐one. Experimental conditions to achieve relatively high molar masses have been established. Thermodynamic parameters such as enthalpy and entropy of 3‐MeDX polymerization as well as ceiling temperature have been determined. Poly(D ,L ‐3‐MeDX) is found to possess a much lower ceiling temperature than poly(1,4‐dioxan‐2‐one). Poly(D ,L ‐3‐MeDX) was characterized using NMR spectroscopy, matrix‐assisted laser desorption ionization mass spectrometry, size exclusion chromatography and differential scanning calorimetry. This polymer is an amorphous material with a glass transition temperature of about ?20 °C. Copyright © 2010 Society of Chemical Industry     

Temperature dependent growth and optical properties of SnO<Subscript>2</Subscript> nanowires and nanobelts

SnO₂ nanowires and nanobelts have been grown by the thermal evaporation of Sn powders. The growth of nanowires and nanobelts has been investigated at different temperatures (750–1000°C). The field emission scanning electron microscopic and transmission electron microscopic studies revealed the growth of nanowires and nano-belts at different growth temperatures. The growth mechanisms of the formation of the nanostructures have also been discussed. X-ray diffraction patterns showed that the nanowires and nanobelts are highly crystalline with tetragonal rutile phase. UV-visible absorption spectrum showed the bulk bandgap value (∼ 3–6 eV) of SnO₂. Photoluminescence spectra demonstrated a Stokes-shifted emission in the wavelength range 558–588 nm. The Raman and Fourier transform infrared spectra revealed the formation of stoichiometric SnO₂ at different growth temperatures.     

Complex two-unit system with preventive maintenance

A two-unit warm standby redundant system with repair and preventive maintenance is considered. The pdf of the life time of a unit while in standby is assumed to be Erlangian. The pdfs of all the other random variables are arbitrary. Identifying suitable regeneration points, expressions for the Laplace transforms of the availability and reliability of the system are derived.     

Investigation of twin-wall structure at the nanometre scale using atomic force microscopy

The structure of twin walls and their interaction with defects has important implications for the behaviour of a variety of materials including ferroelectric, ferroelastic, co-elastic and superconducting crystals. Here, we present a method for investigating the structure of twin walls with nanometre-scale resolution. In this method, the surface topography measured using atomic force microscopy is compared with candidate displacement fields, and this allows for the determination of the twin-wall thickness and other structural features. Moreover, analysis of both complete area images and individual line-scan profiles provides essential information about local mechanisms of twin-wall broadening, which cannot be obtained by existing experimental methods. The method is demonstrated in the ferroelectric material PbTiO(3), and it is shown that the accumulation of point defects is responsible for significant broadening of the twin walls. Such defects are of interest because they contribute to the twin-wall kinetics and hysteresis.     

Effect of mean stress (stress ratio) and aging on fatigue-crack growth in a metastable beta titanium alloy, Ti-10V-2Fe-3Al

The effect of mean stress, or the stress ratio (R), on the fatigue-crack growth (FCG) behavior of α-aged and ω-aged microstructures of the beta titanium alloy Ti-10V-2Fe-3Al was investigated. While the mean stress had a negligible effect on the FCG behavior of the α-aged microstructure, a strong effect was observed in the ω-aged microstructure. In particular, the values of the threshold stress-intensity range (ΔK _th ) exhibited a strong dependence on R in the ω-aged microstructure, while this dependence was weak in the α-aged microstructure. These effects seem to arise primarily from fracture-surface roughness-induced crack closure. The crack closure levels for the α-aged microstructure were found to be very low compared to those for the ω-aged microstructure. Transmission electron microscopy and scanning electron microscopy studies of microstructures and fracture surfaces were performed to gain insight into the deformation characteristics and crack propagation mechanisms, respectively, in these microstructures. The microstructure-induced differences in FCG behavior are rationalized in terms of the effect of aging on slip and crack closure.