Transient liquid phase diffusion bonding of 6061-13 vol.% SiCp composite using Cu powder interlayer: mechanism and interface characterization

Transient liquid phase diffusion bonding of an extruded 6061-13 vol.% SiCp composite at 560 °C, 0.2 MPa, using a 50-μm thick copper powder interlayer with 20 min, 1 h, 2 h, 3 h, and 6 h hold times has been investigated. The isothermal solidification and homogenization of the bond region occurred with 3 and 6 h holding, respectively. During isothermal solidification, smaller SiC particles (size range: 11–13 μm) were pushed by the moving solid/liquid interface and segregated around the bond centerline, whereas bigger SiC particles (size range: 24–33 μm) were engulfed. During isothermal solidification, the bigger SiC particles locally hindered the solidification front movement causing grain refinement. The kinetics of isothermal solidification, representing the displacement of the solid/liquid interface (y, in μm) as a function of time (t, in s), followed a power-law relationship: y = 35 t ^0.22. According to this kinetic equation, the effective diffusivity of copper in composite system was found to be about 10⁵ times higher than the lattice diffusivity indicating the dominance of short circuit diffusion through the defect-rich particle/matrix interface. Ultrasonic investigation of the bond interface indicated that the signal attenuation was strongly correlated with the width of the segregated layer-a feature that decreased with the increasing bonding time. The completion of isothermal solidification was indicated by a sharp rise in the received signal amplitude with a negligible attenuation.     

Shelf Life Enhancement of Butter,Ice-Cream,and Mayonnaise by Addition of Lycopene

Lycopene crystals were incorporated in butter (20 ppm), ice-cream (70 ppm), and mayonnaise (50 ppm) and were analyzed for their sensory characteristics during storage for 4 months. The peroxide value generally increased with the storage time. Higher peroxides and free fatty acids were observed in control samples as compared to that of lycopene-treated products. Lycopene as an antioxidant slowed the development of off-flavor, off-odors, and color changes in lycopene-added butter, ice cream, and mayonnaise during storage as it interrupts the chain of free radicals involved in autoxidation. Results showed that there were insignificant changes in hunter L*, a*, and b* values of butter, ice cream, and mayonnaise during the 4 months of storage. Thus, it could be concluded that lycopene-treated products are in comparison with control market samples. The sensory scores of ice cream, butter, and mayonnaise revealed that the sensory attributes were similar to those of control samples. With increased storage, the sensory scores decreased but a significant decrease was observed in the 4th month of storage for all samples.     

Wave Propagation in an Inhomogeneous Anisotropic Generalized Thermoelastic Solid

The plane wave propagation in an inhomogeneous anisotropic thermally conducting elastic solid is studied with two thermal relaxation times. Three types of plane waves—quasi-P, quasi-S, and thermal waves—are shown to exist. The analytical expressions for their velocities of propagation are obtained. The inhomogeneity drastically affects the velocity of these waves and also depends on the angle of propagation and frequency. The effects of these parameters are shown graphically.     

Dy3+-doped nano-glass ceramics comprising NaAlSiO4 and NaY9Si6O26 nanocrystals for white light generation

The radiative emission properties of the Dy³⁺ ions in oxyfluoride glasses and glass ceramics have been investigated for the generation of white light. The X-ray diffraction pattern of the glass ceramics reveals the presence of NaAlSiO₄ nanocrystals along with secondary phase of NaY₉Si₆O₂₆ in the glass matrix after a suitable thermal treatment of the pristine glasses. Intense white light emission has been observed when the samples are excited with 350 nm light. Yellow to blue emission intensity ratios and chromaticity color coordinates have been determined from the visible luminescence spectra. All color coordinates are found to lie in the white region of the chromaticity color diagram proposing the suitability of the present studied materials for color display devices.     

Nondestructive Evaluation of a Haulage Rope in a Monocable Continuously Moving Passenger Ropeway

The theoretical basis of detecting wire rope anomalies using permanent magnetic field has been fully established. The local faults (LF) such as broken wires and loss of metal area (LMA) signals are provided by nondestructive evaluation instruments. These signals represent the electronic equivalent of the mechanical anomalies present in the wire rope. The saturating magnetic field of the instrument makes the anomalies visible to the magnetic sensors placed around the rope. The condition of a haulage rope (construction 6X19) in a monocable continuously moving passenger ropeway has been studied using this nondestructive method, and the results are presented in this paper.     

α-Glucosidase inhibitory terpenoids from Potentilla fulgens and their quantitative estimation by validated HPLC method

Potentilla fulgens is used extensively in traditional system of medicine and as a food additive for the treatment of diabetes mellitus and other ailments. The present study was aimed to isolate and identify the constituents with α-glucosidase inhibitory activity. The methanolic extract demonstrated potent inhibitory activity against α-glucosidase. Fractionation and purification by silica gel column chromatography and HPLC led to the isolation of five terpenes, namely, hyptadienic acid, tormentic acid, rosamultic acid, 2α,19α-dihydroxy-3-oxo-12-ursen-28-oic acid β-d-glucopyranoside ester and kajiichigoside F1 for the first time from this plant. Among these hyptadienic acid, which is an A-ring contracted triterpenoid, was found to be the most potent against α-glucosidase. This suggests that the A-ring contracted triterpenes may serve as a class of triterpenes with α-glucosidase inhibitory activity. Also, identification of enzyme inhibitory activity of these constituents explains the traditional use of P. fulgens in the management/treatment of diabetes. Quantitative estimation of the compounds was performed using HPLC and the method was validated.     

Nitrophenates of transition metals part I. synthesis and characterisation

Abstract

A large number of nitrophenates of transition metals have been synthesised and characterised during the programme of formulation of new energetic materials. These compounds have been found to be ionic salts and number of water of crystallisation was found to depend upon the number of nitro groups.     

Design of Enterprise Storage Architecture for Optimal Business Continuity

This paper presents a solution for optimal business continuity, with storage architecture for enterprise applications, which will ensure zero data loss and quick recovery. The solution makes use of Internet protocol storage area network （IPSAN）, which is used for data management without burdening the application server, as well as mix of synchronous and semi-synchronous replication techniques to replicate data to remote disaster recovery site. We have presented the detailed design of both synchronous and semi-synchronous with case study of using open source database postgres to prove our point for optimal business continuity. The theoretical presentation is also given for the same.     

Etching of mesa structures in HgCdTe

Mesa structures were etched in HgCdTe using different Br₂/HBr/Ethylene glycol (EG) formulations. Etch rate and degree of anisotropy (A) were studied in detail for all of the combinations. Addition of EG to the conventional etchant gave A>0.5, with controllable etch rates. Optimum etchant composition was determined to be 2% Br₂ in a 3:1 mixture of EG:HBr. This composition resulted in a good anisotropy factor of ∼0.6 and a reasonably optimum etch rate of ∼2.5 μm/min, with rms surface roughness of ∼2 nm. Kinetics of the etching reaction have also been studied for the optimum etchant concentration and an etching mechanism has been proposed.     

Engineered Schottky barriers on n-In0.35Ga0.65As

The Schottky barrier height in Al/n-In_0.35Ga_0.65As was engineered using thin p-type near-interface In_0.35Ga_0.65As layers grown by molecular beam epitaxy. The effect of the thickness and doping level of the p-type layer on the barrier height was also studied by computer simulation. A good agreement was obtained between the calculated and experimental barrier height values. An experimental Schottky barrier height of 0.67 eV with an ideality factor of 1.15 has been achieved.