Thickness-Dependent Mechanical Behaviour of Aluminium-Coated Polyethylene Terephthalate (PET) Films

Mechanical behaviour of aluminium-coated PET films has been investigated through Dynamic Mechanical Analyser. Aluminium is coated on PET substrate by vacuum thermal evaporation method. As thickness of aluminium coating increases from 150 nm to 350 nm, tensile strength decreases from 108.88 MPa to 99.25 MPa. This mechanical behaviour is correlated with microstructure and its evolution with the thickness of aluminium coating. Al-PET film consists of fine globular grains and average grain size increases monotonically with the film thickness. The relative contribution of the grain size to the strength of aluminium thin films is in good agreement with Hall-Patch equation.     

Computer simulation of martensitic textures

We consider a Ginzburg-Landau model free energy F(ε, e₁, e₂) for a (2D) martensitic transition, that provides a unified understanding of varied twin/tweed textures. Here F is a triple well potential in the rectangular strain (ε) order parameter and quadratic e₁², e₂² in the compressional and shear strains, respectively. Random compositional fluctuations η(r) (e.g. in an alloy) are gradient-coupled to ε, ˜ − ∑_rε(r)[(Δ_x² − Δ_y²)η(r)] in a “local-stress” model. We find that the compatibility condition (linking tensor components ε(r) and e₁(r), e₂(r)), together with local variations such as interfaces or η(r) fluctuations, can drive the formation of global elastic textures, through long-range and anisotropic effective ε-ε interactions. We have carried out extensive relaxational computer simulations using the time-dependent Ginzburg-Landau (TDGL) equation that supports our analytic work and shows the spontaneous formation of parallel twins, and chequer-board tweed. The observed microstructure in NiAl and Fe_xPd_{1 − x} alloys can be explained on the basis of our analysis and simulations.     

Hydroxylamine production: will a QRA help you decide?

The recent publication by the US Chemical Safety Board (CSB) concerning its findings on the Concept Sciences Inc. (CSI) incident involving hydroxylamine (HA) has raised issues with regard to safe production of HA. This CSI incident was followed by another incident that destroyed the Nissin Chemical HA plant in Japan, and today BASF is the sole commercial producer of HA. HA is an important solvent in the pharmaceutical industry and is used as an etching agent in the semi-conductor industry.This paper discusses a Quantitative Risk Assessment of a generic HA production plant, which integrates the findings of the CSB report and the knowledge of potential HA reactivity hazards based on research at the Mary Kay O'Connor Process Safety Center. The intent is to highlight safety concerns and major risk factors in the production and handling of HA and to provide risk assessment guidelines for potential manufacturers. These guidelines are also applicable to the production strategies for other hazardous chemicals.     

Regionally different vascular response to vasoactive substances in the remodelled infarcted rat heart; aberrant vasculature in the infarct scar

Remodelling after myocardial infarction (MI) is associated with vascular adaption, increasing vascular capacity of non-infarcted myocardium, and angiogenesis in the infarcted part during wound healing and scarring. We investigated regional vascular reactivity in the infarcted rat heart. Transmural infarction of the left ventricular free wall was induced by coronary artery ligation. After 3 weeks, regional flow during maximal vasodilation (nitroprusside, NPR) and submaximal vasoconstriction (arginine-vasopressin, AVP) were studied in buffer-perfused hearts. The main findings were: (1) a reduced vasodilator response (NPR) in the viable part of the left ventricular free wall, where hypertrophy was most pronounced, resulting in reduced maximal tissue perfusion of the myocardium bordering the scar (19.7 + 0.6 v 25.7 + 1.2 ml/min.g), whereas perfusion of other non-infarcted regions was preserved. (2) A 54% lower vasodilator response (NPR) and a 25% stronger vasoconstriction (AVP) in scar tissue compared to viable parts of MI hearts. Microscopy showed thicker walls of resistance arteries in scar tissue than in viable parts of MI hearts or in sham hearts, morphometrically substantiated by two- to three-fold greater wall/lumen ratios. These data indicate a deviant response of scar vessels of MI hearts, and in the non-infarcted part, a reduced coronary reserve in the most hypertrophied region. Whereas the former may be caused by different vessel structure, the reduced vasodilator reserve of the spared part of the left ventricular free wall may indicate vasodilation at rest due to insufficient vascular growth. Thus, the most hypertrophied region would be at the highest risk of further ischemic damage.     

Band gap determination of Ni-Zn ferrites

Nanocomposites of Ni-Zn with copolymer matrix of aniline and formaldehyde in presence of varying concentrations of zinc ions have been studied at room temperature and normal pressure. The energy band gap of these materials are determined by reflection spectra in the wavelength range 400–850 nm by spectrophotometer at room temperature. From the analysis of reflection spectra, nanocomposites of copolymer of aniline and formaldehyde with Ni_1-xZn_xFe₂O₄ (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 10) have been found to have direct band gaps ranging from 1.50–1.66 eV.     

Crystallization study of Te-Bi-Se glasses

Crystallization studies are carried out under non- isothermal conditions with samples heated at several uniform rates. The dependence of the glass transition temperature (T_g), the crystalline temperature (T_c) and the peak temperature of crystallization (T_p) on the composition and heating rate (β) has been studied. For a memory/switching material, the thermal stability and ease of glass formation are of crucial importance. The glass transition temperature, T_g, increases slightly with the variation of Bi content. From the heating rate dependence of T_g, the activation energy for glass transition (E_t) has been evaluated. The results are discussed on the basis of Kissinger’s approach and are interpreted using the chemically ordered network model (CONM).     

Dependable computing and online testing in adaptive andconfigurable systems

We describe cost-effective design techniques for very dependable high-performance adaptive computing systems. These design techniques take advantage of the particular properties of adaptive computing systems     

Scanning transmission electron microscopy (STEM)-transmission electron microscopy (TEM) analysis of nitrogen ion implanted austenitic 302 stainless steel

The microstructure of nitrogen implanted AISI 302 austenitic stainless steel and the effect of long-term room temperature ageing on it have been studied. Samples were implanted in 1992 with 2.5×10²¹ N₂⁺ m⁻² at 130 keV. The characteristics of the implanted layer and the depth profile have been investigated by scanning transmission electron microscope combined with energy dispersive X-ray spectrometry. Electron diffraction patterns recorded in the implanted layer using transmission electron microscopy confirm the formation of CrN along with the presence of Cr₂N. The identification of phases by glancing angle X-ray diffraction also indicates the formation of Cr₂N and nitrogen solid solutions. The effects of ageing on the microstructure are observed to be small.     

Heavy metal pollution in a sewage-fed lake of Bhopal, (M. P.) India

Shahpura Lake receives untreated domestic sewage from residential areas in Bhopal city. Analysis of water, plankton, fish and sediment reveals that the lake is contaminated by certain heavy metals. The concentrations of some of these metals including iron and manganese were within acceptable limits, whereas others including chromium, nickel, zinc and lead were not within acceptable water quality limits. Metal concentrations in the sewage inlet drain and lake sediment were compared with published criteria. The comparison revealed that the metals in the sediment ranged from the ‘non‐polluted’ to the ‘heavy pollution’ categories. The reference dose was calculated by the adoption of the United States Environmental Protection Agency reference dose factor, and the result reveals that the local population is not exposed to undue health risks. Concentrations of heavy metals in the water increased during the second year of the study, indicating an increase in the pollution load on the system. This might increase the bioaccumulation levels in fish and increase the actual dose of metals to which the local population will be exposed.     

Improvement in Strength and Moduli of Coal Ash Stabilized with Bentonite and Compacted at Various Unit Weights

With the increasing demand for electricity on one hand and the depleting resources of natural gas and oil on the other, the coal industry has been working hard for satiating the demand. The use of the fossil fuel to produce electricity may be cheaper but it has its own limitations because of the amount of nondegradable waste that it generates as a byproduct. Although coal is being primarily used to produce electricity, researchers are striving to develop cost effective and environmentally safe uses of coal combustion products. The use of bottom ash generated from burning of pulverized coal to produce electricity amended with various admixtures as a structural fill and low hydraulic conductivity barriers has been studied by several researchers. In general, the fill material in the field is compacted close to the maximum dry unit weight obtained from a standard Proctor test. In this investigation, change in the strength and stiffness of PCC bottom ash samples amended with varying amount of bentonite and compacted to various dry unit weights was studied. The stiffness was measured in terms of secant modulus at maximum stress, secant modulus at half of the maximum stress, and initial tangent modulus. The results presented show that both the strength and secant moduli of the mixtures increased with the increase in the unit weight. The initial tangent modulus of the mixtures also increased with the increase in dry unit weight, but beyond a unit weight of approximately 15?kN/m3 (100?pcf), the change in the initial tangent modulus was observed to be negligible.