ERD facility for analysis of hydrogen and deuterium in solids

Hydrogen is the lightest element in nature, and so, its detection and quantitative analysis is difficult by the conventional methods utilized for other elements. In the recent years the technique of elastic recoil detection analysis (ERD) using 1–2 MeV He⁺ beam has been developed to quantitatively and simultaneously analyze hydrogen and its isotopes in solids. Such a facility has been set up using the 2 MeV Van-de-Graaff accelerator at IIT Kanpur. It facilitates H and D analysis in a material up to a depth of ∼ 1μm with a detection sensitivity of 0·1 at.% and depth resolution of about 300 ?. The application potential of this setup is illustrated by presenting the results of measurements performed on Al:H:D systems prepared by plasma source ion implantation and highT _c YBCO pellets exposed to humid atmosphere.     

Chromophoric chain β-aryl-substituted styryl cyanines: effect of substituents on visible absorption spectra and photosensitisation properties

A number of chromophoric chain β-aryl-substituted (CCBAS) styryl cyanines (hemicyanines) have been synthesised by condensing substituted quaternised quinaldine bases with substituted benzophenones, with a view to studying the effect of the aryl substituents on their visible absorption and silver halide photosensitisation properties.The dyes absorb at longer wavelengths than the unsubstituted analogues, showing uniform bathochromic shifts and extra-photosensitisation properties, which corroborate the authors' previous findings.Irrespective of the nature of the substituent attached to the chromophoric β-phenyl group, electron withdrawing and donating groups result in a bathochromic shift of the visible absorption band and extension of the extra-photosensitisation in most cases.     

Quantitative fractography: A modern perspective

The important aspects of quantitative fractography as a new analytical tool for understanding material fracture are discussed. The special considerations that rise in the quantification problems are examined from the purview of stereology. Two major experimental techniques for obtaining geometrical information about the fracture surface topography are critically evaluated. These methods are based on stereophotogrammetry or vertical sectioning procedures-both of which yield estimates of the true fracture surface area. The profile and surface roughness parameters which are required to transform measurements made on flat SEM fractographs to the true quantities in the fracture surface are introduced. The two roughness parameters are related by a simple parametric equation, permitting the fracture surface area to be calculated from the experimental measurement of the profile roughness parameter. Alternatively, it is shown how the fracture surface area can be obtained from the angular distribution of the profile elements by employing a transform procedure. The concept of “fractals” as it applies to quantitative fractography is introduced. Recently developed relationships which describe the true variation of the profile and surface roughness parameters with the size of the measuring unit are presented. Calculations are made of the mean area and perimeter length of dimples in the fracture surface of a 4340 steel. Three fracture surface configurations are examined: (1) an assumed flat- , (2) an assumed randomly-oriented- , and (3) the actual partially-oriented fracture surface. Significant differences are demonstrated between the true and the assumed situations, illustrating the importance of quantitative methods in fractography. By means of examples, it is shown how the quantitative methods permit detection of subtle changes in the fracture surface topography as influenced by the materials’ microstructure. This paper is based on a presentation made at the symposium “Stochastic Aspects of Fracture” held at the 1986 annual AIME meeting in New Orleans, LA, on March 2-6, 1986, under the auspices of the ASM/MSD Flow and Fracture Committee.     

Studies on Some Minor Oilseeds

The seeds from three plant species have been analysed for oil and protein contents and fatty acid composition. All the seeds were rich in oil and protein. The oil from Myroxylon balsamum contained four newly identified acids. The sum of oleic and linoleic acids in these oils ranged from 70.7-74.8%.     

Electron beam irradiation of ethylene‐propylene terpolymer: Evaluation of trimethylol propane trimethacrylate as a crosslink promoter

The effect of electron beam irradiation on ethylene‐propylene terpolymer (EPDM) was investigated. A 50‐part oil‐extended EPDM with high termonomer (ENB) content (iodine number of base polymer) 19, was selected for this study. An increase in irradiation dose from 0 to 200 kGy resulted in increased crosslinking, measured by an increase in gel contents and better swelling resistance. The effect of the multifunctional monomer trimethylol propane trimethacrylate (TMPTMA) as a crosslink promoter was studied using IR spectroscopy. The IR studies revealed enhanced peak absorbances at 1725, 1257, and 1023 cm^?1 as a result of the increased concentration of C = O and C‐O‐C groups and reduced absorbance at 1630 cm^?1 due decreased concentration of C = C groups with TMPTMA level in the irradiated samples. The presence of TMPTMA increased the level of crosslinking at a given irradiation dose, which was manifested by improvement in tensile properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 968–975, 2005     

Metallographic investigation of TiC nucleants in the newly developed Al-Ti-C grain refiner

For grain refinement of aluminium and its alloys, a new aluminium-based master alloy containing TiC nucleants was developed a few years ago, by reacting carbon with Al-Ti binary alloy melt. However, as the melt was held at the usual melting temperatures of below 1273 K, the resultant master alloy lost its grain-refining efficiency, and so this phenomenon was called the poisoning effect. Nevertheless, a superheating treatment of the melt at higher temperatures (> 1523 K) rejuvenated the nucleant particles. The present investigation, dealing with electron diffraction of carbide particles extracted from the poisoned master alloy, revealed massive formation of Al₄C₃ and Ti₃AlC, of which Al₄C₃ appears to account for the poisoning of TiC nucleants. On the other hand, subsequent electron diffraction studies on the rejuvenated nucleants confirmed that they were essentially composed of uncontaminated TiC.     

Phase-precipitation studies of Fe-B-Si metallic glasses using Mössbauer spectroscopy

Phase-precipitation studies have been performed on samples of the metallic glasses Fe₇₉B₁₆Si₅ and Fe₇₈B₁₃Si₉, heated in the range 300–475 °C for various times (1–16 h) using ⁵⁷Fe Mössbauer transmission spectroscopy and X-ray diffraction methods. These measurements have helped in identifying the temperature ranges and annealing durations in which the amorphous structure of these metallic glasses is retained. The results revealed that the thermal stability increases as boron is replaced by silicon in the Fe-B-Si metallic glasses and that these alloys remain amorphous below 450 °C. The various phases precipitated above this temperature were identified as -Fe, -(Fe, Si), Fe₃B, and Fe₂B. The direction of magnetization in the two metallic glasses appears to change upon annealing.     

Assessment of Shear Stress Distribution in Meandering Compound Channels with Differential Roughness Through Various Artificial Intelligence Approach

Water Resources Management - Accurate prediction of shear stress distribution along the boundary in an open channel is the key to solving numerous critical engineering problems such as flood...