Mechanisms underlying electro-mechanical dysfunction in the Zucker diabetic fatty rat heart: a model of obesity and type 2 diabetes

Diabetes mellitus (DM) is a major and worsening global health problem, currently affecting over 450 million people and reducing their quality of life. Type 2 diabetes mellitus (T2DM) accounts for more than 90% of DM and the global epidemic of obesity, which largely explains the dramatic increase in the incidence and prevalence of T2DM in the past 20 years. Obesity is a major risk factor for DM which is a major cause of morbidity and mortality in diabetic patients. The electro-mechanical function of the heart is frequently compromised in diabetic patients. The aim of this review is to discuss the pathophysiology of electro-mechanical dysfunction in the diabetic heart and in particular, the Zucker diabetic fatty (ZDF) rat heart, a well-studied model of T2DM and obesity

Thermal expansion behaviour of nanocrystalline titanium powder compacts

This investigation is an attempt to understand the expansion behaviour of compacts of nanocrystalline titanium powder during thermal treatments. Entrapped gases cause excessive expansion in the green compacts. The dilatometric study reveals that there is no significant difference in the expansion coefficient of sintered nanocrystalline titanium samples, compared to their micron-size counterpart. (c) 2005 Elsevier BX

Dilatometry of attrition milled nanocrystalline titanium powders

The sintering behavior of nanosized titanium powders was investigated by ditatometry. The nanosized Ti powders (40 nm) were produced by the attrition milling of micron sized Ti powders (12 mu m) in Ar atmosphere. Sintering was carried out in Ar atmosphere in the temperature range of 450-1250 degrees C for nanosized Ti and 650-1250 degrees C for micron sized Ti by heating at 10 degrees C/min, up to the sintering temperature followed by isothermal holding for I It. The nanosized Ti powders exhibited a lower sintering onset temperature, larger shrinkage, larger shrinkage rate, and lower activation energy for sintering as compared to the micron sized Ti powders. The sintered micron sized Ti specimens exhibited both intraagglomerate and interagglomerate porosity while the nanosized Ti specimens exhibited well densified agglomerates (almost no interagglomerate porosity) and large intraagglomerate porosity. In nanosized Ti grain growth was found to take place beyond 700 degrees C and reached a maximum of 66 nm in samples sintered at 1100 degrees C. (c) 200

Effect of minute element addition on the oxidation resistance of FeCoCrNiAl and FeCoCrNi2Al high entropy alloy

The effect of Ti0.1 and Ti0.1Si0.1 addition on the high temperature isothermal oxidation behavior of dense FeCoCrNiAl and FeCoCrNi2Al high entropy alloy (HEA) consolidated by vacuum hot pressing were investigated by X-ray diffraction, Scanning Electron Microscopy and Raman Spectroscopy. Mechanical properties such as hardness, Young's modulus, and thermal properties such as differential scanning calorimetry (DSC) and coefficient of thermal expansion (CTE) were also investigated. The weight gain recorded after isothermal oxidation for 5,25,50 and 100 h at 1050 °C was found to be parabolic in nature. X-ray diffraction analysis (XRD), as well as Raman spectroscopy analysis of HEA's oxidized at 1050 °C for 100 h, shows the formation of the Al2O3 phase. A homogeneous thin oxide scale without any discontinuity was observed throughout the cross-section. Ti and Si addition in 0.1 at. % improves mechanical properties, oxidation resistance, and reduces waviness of the oxide scale

Artificial neural network modeling on the relative importance of alloying elements and heat treatment temperature to the stability of alpha and beta phase in titanium alloys

An artificial neural network model was developed to correlate the relationship between the alloying elements (Al, V, Fe, O, and N) and heat treatment temperature (inputs) with the volume fractions of alpha and beta phases (outputs) in some alpha, near-alpha, and alpha + beta titanium alloys. The individual and combined influences of the composition and temperature on a and b phases were simulated through performing sensitivity analysis. A new method has been proposed to estimate the relative importance of the inputs on the outputs for single phase alpha-Ti, near-alpha Ti, and alpha + beta Ti alloys. The average error of the model predictions for 35 unseen test data sets is 1.546%. The estimated behavior of volume fractions of alpha and beta phases as a function of composition and temperature are in good agreement with the experimental knowledge. Justification of the results from the metallurgical interpretation has been included. (C) 2015 Elsevier B.V. All rights reserved.1187sciescopu

Sintering mechanisms of attrition milled titanium nano powder

Detailed sintering Studies have been carried out on attrition milled nanocrystalline titanium powder through isothermal dilatometry over a temperature range of 300-1250 degrees C along with microstructural and x-ray diffraction studies. The sintering behavior of attrition milled nanocrystalline titanium appears to be characterized by: (i) very low activation energies, (ii) high shrinkage anisotropy, (iii) very rapid grain growth in the beta range, and (iv) two kinds of densification processes, namely, intra-agglomerate and inter-agglomerate. Analysis of the kinetic data through sintering diagram approach indicates the operation of particle sliding and grain boundary rotation, type of mechanism in addition to the grain-boundary diffusion, and lattice diffusion as the dominant mass transport mechanisms

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Effect of asymmetric rolling on plastic anisotropy of low carbon steels during simple shear tests.

Simple shear tests are performed on low carbon steel pre-deformed in conventional, asymmetric and orthogonal-asymmetric rolling. The simple-shear tests were carried out at 0 degrees, 45 degrees and 135 degrees with respect to the previous rolling direction. For a reduction ratio of 15%, a transient stagnation in the hardening rate is observed at reloading for all changes in strain path. The shear stress level, the hardening rate and extent of the plateau appear to be insensitive to the preliminary applied rolling conditions. After a reduction ratio of 50%, plastic instability was detected at reloading for all the changes of strain path and rolling conditions studied. A specific heat treatment was then designed allowing the material to become ductile after rolling while retaining the fine microstructure and therefore the high strength. Promising results were obtained essentially for 45 degrees shear tests.open1111sciescopu