Ultrasonic velocity measurements for characterizing the annealing behaviour of cold worked austenitic stainless steel

Precise measurements of shear wave velocities have been made in 20% cold worked and annealed samples of alloy D9 (Ti-modified austenitic stainless steel) to characterize the microstructural changes during annealing. The variation in wave velocity with annealing time exhibited a three stage behaviour. In the first stage, a slight increase in the velocity during recovery regime has been observed. This is followed by a significant increase in the velocity in the recrystallization regime (second stage) and reaching saturation on completion of recrystallization (third stage). Microstructural observations using optical metallography confirmed these three stages. The maximum variation in velocity is observed only when the polarization or the propagation direction of the shear wave is alingned with the cold working direction. Variation in shear wave velocity during annealing process, in general, is just opposite to that of the variation in longitudinal wave velocity. A number of velocity measurements were made by changing the propagation and polarization directions of the shear waves with respect to the cold working direction. Based on these measurements, a suitable velocity ratio parameter is suggested for determining the degree of recrystallization during annealing of cold worked alloy D9.     

Effects of SiO<Subscript>2</Subscript> substitution on wettability of laser deposited Ca-P biocoating on Ti-6Al-4V

Silicon (Si) substitution in the crystal structure of calcium phosphate (CaP) ceramics has proved to generate materials with improved bioactivity than their stoichiometric counterpart. In light of this, in the current work, 100 wt% hydroxyapatite (HA) precursor and 25 wt% SiO₂-HA precursors were used to prepare bioactive coatings on Ti-6Al-4V substrates by a laser cladding technique. The effects of SiO₂ on phase constituents, crystallite size, surface roughness, and surface energy of the CaP coatings were studied. Furthermore, on the basis of these results, the effects and roles of SiO₂ substitution in HA were systematically discussed. X-ray diffraction analysis of the coated samples indicated the presence of various phases such as CaTiO₃, Ca₂SiO₄, Ca₃(PO₄)₂, TiO₂ (Anatase), and TiO₂ (Rutile). The addition of SiO₂ in the HA precursor resulted in the refinement of grain size. Confocal laser microscopy characterization of the surface morphology demonstrated an improved surface roughness for samples with 25 wt% SiO₂-HA precursor compared to the samples with 100 wt% HA precursor processed at 125 cm/min laser speed. The addition of SiO₂ in the HA precursor resulted in the highest surface energy, increased hydrophilicity, and improved biomineralization as compared to the control (untreated Ti-6Al-4V) and the sample with 100 wt% HA as precursor. The microstructural evolution observed using a scanning electron microscopy indicated that the addition of SiO₂ in the HA precursor resulted in the presence of reduced cracking across the cross-section of the bioceramic coating.     

Coal washing scenario in India and future prospects

International Journal of Coal Science & Technology - Coal Washing Exploration in India dates back to 1900s; though, first coking coal washeries in India were installed after independence. At...     

Value‐added products from underutilized fish species

Fish is a rich source of easily digestible protein that also provides polyunsaturated fatty acids, vitamins, and minerals for human nutrition. Nonetheless, a large proportion of total landed fish remains unused due to inherent problems related to unattractive color, flavor, texture, small size, and high fat content. Most of these underutilized fish belong to the abundantly available pelagic species, which are landed as bycatch, and some are unconventional species such as krill. Although some species are used industrially for fish meal manufacture, a need for their conservation and utilization for human consumption has been recognized in order to prevent post‐harvest fishery losses. Recovery of flesh by mechanical deboning and development of value‐added products are probably the most promising approaches. This article discusses various possibilities for product development using mince from low‐cost fishery resources. These include surimi and surimi‐based products, sausages, fermented products, protein concentrates and hydrolysates, extruded products, and biotechnological possibilities. The dual advantages of this approach, namely, finding ways for better utilization of low‐value fish species and providing protein‐rich convenience foods, have been pointed out. However, the key to the success of this approach depends largely on the market strategies utilized.     

Experimental Investigation of the Thermal Performance of Graphite Foam for Evaporator Enhancement in Both Pool Boiling and an FC-72 Thermosyphon

High-conductivity graphite foam is investigated for use as a surface enhancement for improved thermal performance in both pool boiling and an FC-72 thermosyphon. The influences of heat load and fluid level on the overall system thermal performance including surface superheat, effective heat transfer coefficient, and thermal resistance are examined. The thermal resistance of the foam heat sink is found to be extremely low at a minimum of 0.024 K/W, well below that of many other methods. The featured low thermal resistance is the primary benefit of this system. The thermal resistance is found to rise with increasing heat flux, but still remains advantageously low and exhibits excellent potential for high heat flux dissipation with low surface superheat, making it suitable for thermal management of advanced electronics.     

Equilibrium pressure measurements in the Li-N-H system by static manometric method

The equilibrium pressure over the phase mixture (Li₂NH + LiNH₂ + LiH) was measured from 343 to 683 K by static manometric method. The plot of ln (p_eq/p⁰) versus (1/T) showed three distinct temperature regions with different slopes. Analysis of the equilibrium gas composition in each temperature regions revealed that the equilibrium gas is a mixture of H₂, NH₃ and N₂ below 443 K whereas above 443 K, the equilibrium gas is mainly H₂. The enthalpy and entropy of the reaction of H₂ with Li₂NH to form LiNH₂ and LiH are found to be −55.0 ± 1.3 kJ?mol⁻¹ and −86 ± 2 J?K⁻¹?mol⁻¹, respectively at 523 K, where LiNH₂ exists in the solid state and −18.5 ± 0.5 kJ?mol⁻¹ and −26 ± 1 J?K⁻¹?mol⁻¹, respectively at 658 K, where LiNH₂ exists in the liquid state. The enthalpy and entropy of melting of solid LiNH₂ are calculated as 36.5 ± 1.4 kJ?mol⁻¹ and 60 ± 2 J?K⁻¹?mol⁻¹, respectively.     

Some studies on the warm solid- and hollow-extrusion of sintered powder metallurgical copper preforms

The warm extrusion of sintered P/M preforms of electrolytically pure copper has been investigated for extrusion strains of 0.35, 0.5, 0.66 and 0.81 for the solid configuration and 0.43, 0.62, 0.85 and 1.09 for the tubular configuration at temperatures of 303, 363, 433, 493 and 563 K with densities of 7.45 and 7.90 g cm⁻³ for the solid configuration and 7.0 and 7.7 g cm⁻³ for the tubular configuration. Force requirements and microstructural property evaluation have been attempted. Using the standard axial ring-compression test on the initial preforms, the plastic properties were evaluated to enable the computation of theoretical forces. The actual forces were compared with these theoretical forces and a correction factor, φ, then determined. The influence of strain, temperature and the geometry in ensuring near to theoretical density of the extrudates has been assessed.     

Disk diffusion susceptibility testing of dermatophytes with imidazoles

Flupirtine belongs to the class of triaminopyridines and is successfully applied clinically as a non-opiate analgesic drug with additional muscle relaxant properties. Recently it was reported that flupirtine acts like an antagonist of the N-methyl-D-aspartate (NMDA) receptor complex in neuronal cells both in vitro and in vivo. Here we have used primary cortical cells from rat embryos to demonstrate that this compound is also neuroprotective against the toxic effects caused by the prion agent PrPSc and lead acetate (Pb). These two agents display pleiotropic effects on neurons, which include activation of the NMDA receptor complex. At concentrations above 30 microM the toxic-peptide fragment of PrPSc causes apoptotic fragmentation of DNA and is consequently neurotoxic. Pb is neurotoxic at concentrations above 10 microM. Co-administration of flupirtine (10 microM) with either of these agents resulted in reduced neurotoxicity. These data indicate that the cytoprotective effect of flupirtine is measurable in vitro against these noxious agents which show their effects, including modulation of the NMDA receptor complex, pleiotropically.     

Influence of scattering and two-photon absorption on the optical loss in GaAs-Al/sub 2/O/sub 3/ nonlinear waveguides measured using femtosecond pulses

The influence of scattering and two-photon absorption on the optical loss in GaAs-Al/sub 2/O/sub 3/ semiconductor nonlinear waveguides has been studied using femtosecond pulses. By deploying a scattering technique, loss coefficients were evaluated over an extended wavelength range of 1.3-2.1 /spl mu/m in the near-infrared. A systematic study involving intensity and wavelength dependence of the loss revealed the presence of two-photon absorption for wavelengths below 1.6 /spl mu/m. A simple nonlinear transmission study enabled the separation of the two-photon absorption coefficient from scattering and linear absorption. The calculated two-photon absorption coefficients were /spl sim/9-20 cm/GW.