Growth and thermal studies of SnSe single crystals

Single crystals of SnSe have been grown by a direct vapour transport (DVT) technique. The confirmation of single crystallinity and lattice parameter determination of the grown crystals have been made by using electron and X-ray diffraction techniques respectively. The thermal analysis of the crystals has been studied by the well known TGA and DTA techniques. The results obtained during the analysis showed the stability of SnSe phase at higher temperatures. The implications of the results have been discussed.     

Three dimensional flow field due to a vortex and source line spanning an annulus

A theoretical investigation of the three dimensional potential flow field due to a vortex and source line spanning an annulus is carried out in this paper. The three dimensional effects due to finite radius hub and annulus walls are found to be appreciable, especially for a low hub/tip ratio configuration. The discrepancy between the two and three dimensional solutions are found to be large near the hub, moderate at the tip and negligibly small at the mid radius.     

A simple spectrophotometric method for the determination of carbofuran residues

A method has been developed for carbofuran residues, based on coupling carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methyl carbamate) with diazotized aniline to form a yellow compound with an absorption maximum at 460 nm. The relationship between absorbance and concentration is linear for 1-10 mug carbofuran/5 ml. The method is sensitive and can be applied to the determination of levels as low as 0.025 ppm carbofuran in a 40 g crop or soil sample.     

Changes in fatty acids during maturation of Coriandrum sativum seeds

Changes in fatty acids were studied during maturation ofCoriandrum sativumseeds. The seeds matured in 50 days after flowering. Lipid synthesis proceeded at a steady rate up to 40 days after flowering. Reductive ozonolysis of the monoenes followed by gas liquid Chromatographic analysis of the aldehydic fragments as dioxolanes of 1,3-propanediol was employed to estimate petroselenate (octadeca-cis-6-enoate) in the presence of oleate (octadeca-cis-9-enoate). Petroselenic acid was the major fatty acid at all stages.     

Changes in the coliform populations of the shoreline waters,Shediac, New Brunswick

This paper presents the results of a survey of the changes in the coliform populations of the shoreline waters, Shediac, New Brunswick. The sanitary quality of these waters showed more than 1000 organisms/100 ml of coliforms thereby indicating post-winter and pre-summer contamination of these waters. The membrane filter method is found to be equally efficient to that of the MPN method. The sanitary quality of these waters in relation to other ecological parameters like temperature, pH salinity and availability of oxygen are considered.     

Texture and residual strain in two SiC/Ti-6-2-4-2 titanium composites

Residual strain and texture variations were measured in two titanium matrix composites reinforced with silicon carbide fibers (Ti/SiC) of similar composition but fabricated by different processing routes. Each composite comprised a Ti-6242 α/β matrix alloy containing vol 35 pct continuous SiC fibers. In one, the matrix was produced by a plasma sprayed (PS) route, and in the other by a wiredrawn (WD) process. The PS and WD composites were reinforced with SCS-6 (SiC) and Trimarc (SiC) fibers, respectively. The texture in the titanium matrices differed significantly. The titanium matrix for the PS material exhibited random texture pre and post fabrication of the composite. For the WD material, the starting texture of the monolithic titanium matrix was ≈17 times random, but after consolidation into composite form, it was ≈6 times random. No significant differences were noted in the fiber-induced matrix residual strains between the composites prepared by the two procedures. However, the Trimarc (WD) fibers recorded higher (≈1.3 times) compressive strains than the SCS-6 (PS) fibers. Stresses and stress balance results are reported. Plane-specific elastic moduli, measured in load tests on the unreinforced matrices, showed little difference. This article is based on a presentation made in the Symposium “Mechanisms and Mechanics of Composites Fracture” held October 11–15, 1998, at the TMS Fall Meeting in Rosemont, Illinois, under the auspices of the TMS-SMD/ASM-MSCTS Composite Materials Committee.     

Influence of extraction conditions on polyphenols content and cream constituents in black tea extracts

Increase in water‐to‐tea ratio and extraction time increased polyphenols recovery as well as extractable‐solids‐yield (ESY) in black tea extracts. Polyphenols content‐in‐extracted solids (PES) used as a tea quality parameter, was significantly higher at 50:1 water‐to‐tea ratio and favourably improved only up to 60 min. Extending the extraction period beyond 40 min degraded theaflavins (TF) and also affected the recovery of major catechins. Although tea cream content showed a decrease with increase in water‐to‐tea ratio, the content was nearly the same (1.80–1.89%) in all these extracts when measured at a uniform 0.5% solids concentration. The extraction conditions displayed a similar influence on the other tea cream components, namely, caffeine, calcium, pectin and protein. The conditions optimised (50:1 water‐to‐tea ratio and 40 min) based on higher PES and TF/TR ratio gave a maximum PES of 0.566 g g^?1 and TF of 0.46% (black tea) in the extract.     

Hybrid nanofluid flow over a stretched cylinder with the impact of homogeneous–heterogeneous reactions and Cattaneo–Christov heat flux: Series solution and numerical simulation

The Catteno–Christov heat flux plays a dynamic role in flow of heat enhancement in various manufacturing, industrial, and engineering applications. This present work focuses on the influence of Catteno–Christov heat flux model on Darcy–Forchheimer flow of a hybrid nanofluid placed in a porous medium. The formulation of the mathematical model is done by considering a fluid with two different nanoparticles Al₂O₃ and Cu dispersed in the water as the base fluid. The set of partial differntial equations is reduced by using similarity variables and boundary conditions to obtain ordinary differntial equations. The coupled nonlinear governing differential equations are solved using Runge–Kutta fourth–fifth order (RKF-45). The impact of numerous dimensionless parameters on the velocity, thermal, and concentration profiles are plotted and studied. Furthermore, the coefficient of skin friction for the relevant parameters are analysed through graphs. Result reveals that, increase in the porosity parameter declines the velocity gradient and shoots up the thermal and concentration gradients. Inclination in magnetic parameter declines velocity and concentration profiles due to the Lorentz force. Enhancement in the thermal relaxation parameter declines the thermal profile. Inclination in homogeneous-heterogeneous reaction parameters declines the mass transfer rate. Also, the well-known differential transform method is used for the validity of RKF-45 method and an impressive agreement is noticed between the results of RKF-45 and DTM.