Tailoring the Processing Route to Optimize the Strength–Toughness Combination of Pearlitic Steel

Metallurgical and Materials Transactions A - The present study fine tunes the processing route of a eutectoid steel to shape an optimum strength–toughness combination through appropriate...     

Steady state thermoelastic contact problem in a functionally graded material

This paper is concerned with the stationary plane contact of a functionally graded heat conducting punch and a rigid insulated half-space. The frictional heat generation inside the contact region due to sliding of the punch over the half-space surface and the heat radiation outside the contact region are taken into account. Elastic coefficient μ, thermal expansion coefficient α_t and coefficient of thermal conductivity k are assumed to vary along the normal to the plane of contact. With the help of Fourier integral transform the problem is reduced to a system of two singular integral equations. The equations are solved numerically. The effects of nonhomogeneity parameters in FGMs and thermal effect are discussed and shown graphically.     

Hierarchical pseudo-cubic hematite nanoparticle as formaldehyde sensor

To develop a low cost and scalable gas, sensor for the detection of toxic and flammable gases with fast response and high sensitivity is extremely important for monitoring environmental pollution. This work reports a facile method for preparing pseudo-cubic hierarchical α-Fe₂O₃ nanostructured materials as well as their implementation in gas sensor application. The α-Fe₂O₃ is developed using Fe(NO₃)₃ and ethylene glycol followed by a facile and one-step solvo-thermal reaction without subsequent heat treatment. The pseudo-cubic nanostructures were having an average edge length of 5–10 nm. The solvent played the role of ligand and synergistically affected olation and oxolation process along with dehydration to form final product. The sensor performance of α-Fe₂O₃ in the detection of toxic and flammable gases such as formaldehyde (HCHO), ethanol (C₂H₅OH), and carbon monoxide (CO) was evaluated. As-synthesized nanostructured hematite showed better sensing performance towards formaldehyde. The fabricated gas sensor showed temperature sensitivity sensing performance for the same gas. In addition, ethanol, formaldehyde vapours, and carbon monoxide gas-sensing properties were tested and the sensing performance of the synthesized material was found to be in the order of HCHO > C₂H₅OH > CO. This sensing performance is attributed to the large specific surface area of the pseudo-cubic nanoparticles.     

Effect of Bi doping on magnetoresistance in La(0.7-x) Bi(x)Sr0.3MnO3

It is shown that upon increasing Bi content (x) in La(0.7-x)Bi(x)Sr0.3MnO3, the ground state changes from ferromagnetic metal (x = 0) to charge ordered antiferromagnetic insulator (x > 0.4). The x = 0.3 compound shows unusual magnetic and magnetoresistive properties: it shows hysteresis in magnetization as a function of temperature, field-induced metamagnetic transition in the paramagnetic state, and nearly 100% magnetoresistance. The magnetoresistance as a function of composition at microH = 5 T increases from 38% for x = 0.05 to 99.6% for x = 0.3 and then drops to 60% for x = 0.4. The unusual behavior of x = 0.3 composition is suggested to coexistence of short-range charge-ordered clusters and ferromagnetic domains. The field-induced melting of these charge-ordered clusters leads to large magnetoresistance effect.     

Phosphorylation of the hepatitis delta virus antigens

We used two-dimensional electrophoresis (nonequilibrium pH gradient electrophoresis followed by sodium dodecyl sulfate-10% polyacrylamide gel electrophoresis) coupled with 32P labeling and immunoblotting detection with 125I-protein A to detect and quantitate phosphorylation of the large and small forms of the delta antigen (deltaAg-L and deltaAg-S, respectively). Analysis of deltaAg species from the serum and liver of an infected woodchuck as well as deltaAg species expressed in and secreted from transfected Huh7 cells revealed the following. (i) No detectable phosphorylation of deltaAg-S occurred. (ii) In virions from the serum of an infected animal and in the particles secreted from cotransfected cells, none of the deltaAg-L was phosphorylated. (iii) Only in the infected liver and in transfected cells was any phosphorylation detected; it corresponded to a monophosphorylated form of deltaAg-L. Given these results, we carried out serine-to-alanine mutagenesis of the deltaAg-L to determine whether the monophosphorylation was predominantly at a specific site on the unique 19-amino-acid (aa) extension. We mutated each of the two serines, aa 207 and 210, on this extension and also the serine at aa 177. These three mutations had no significant effect on phosphorylation. In contrast, mutagenesis to alanine of the cysteine at aa 211, which normally acts as the acceptor for farnesylation, completely inhibited phosphorylation. Our interpretation is that the site(s) of phosphorylation is probably not in the 19-aa extension unique to deltaAg-L and that phosphorylation of deltaAg-L may depend upon prior farnesylation. The possible significance of the intracellular phosphorylated forms of deltaAg-L is discussed.     

Doped barium titanate nanoparticles

We have synthesized nickel (Ni) and iron (Fe) ion doped BaTiO₃ nanoparticles through a chemical route using polyvinyl alcohol (PVA). The concentration of dopant varies from 0 to 2 mole% in the specimens. The results from X-ray diffractograms and transmission electron micrographs show that the particle diameters in the specimen lie in the range 24–40 nm. It is seen that the dielectric permittivity in doped specimens is enhanced by an order of magnitude compared to undoped barium titanate ceramics. The dielectric permittivity shows maxima at 0.3 mole% doping of Fe ion and 0.6 mole% of Ni ion. The unusual dielectric behaviour of the specimens is explained in terms of the change in crystalline structure of the specimens.     

The Effect of Selective Additives on the Rheological Behavior of Power Plant Ash Slurry

The rheological behavior of power plant ash samples collected from JSPL (M/s Jindal Steel & Power Limited, Raigarh), India, was carried out using a HAAKE rotational rheometer (Model: RheoStress 1, Thermo Fisher Scientific). The ash slurry indicated non-Newtonian behavior in the solids concentration range of 50–60% by mass. The rheological data were best fitted by Bingham plastic model in the studied ranges of concentrations and shear rates. Two selective additives, namely sodium silicate and Ghadi detergent, were applied in small quantities (0–0.6% of total solids) and their effects on rheological parameters were evaluated. It was indicated that the small dosage of sodium silicate substantially influenced the Bingham parameters of the ash slurry than the Ghadi detergent. The percentage reduction in Yield stress at a slurry concentration of 60% by weight were found to be 59.3% and 46.23% for sodium silicate and Ghadi detergent, respectively, at a maximum dosage of 0.6% additives. More importantly, the plastic viscosity reduced by 37.6% and 16.3%, respectively, with the same dosage of sodium silicate and Ghadi detergent at same slurry concentration.     

Nature of thermodynamic fluctuations in the electrical conductivity of Y-Ba-Cu-O pellets and tapes containing silver

Results on the temperature dependence of the electrical resistivity of single-phase silver-doped Y-Ba-Cu-O pellets and tapes, prepared by a coprecipitation technique, are presented. The excess electrical conductivity nearT>T _c is analyzed using Aslamzov-Larkin (AL) formulations. Silver addition in Y-Ba-Cu-O influences strongly the temperature range of both the 3D and 2D regions. The lower limit of the breakdown temperature of the mean-field region (x=–0.5) shifts toward higher temperatures as the concentration of Ag increases in Y-Ba-Cu-O. For samples with higher Ag contents, a third region with critical exponent x=–0.28 is seen beyond the mean-field region. This possibly indicates the appearance of a fully critical 3D region, where dynamic scaling theory applies.