Dislocation models of mechanoluminescence in γ- and X-irradiated alkali halides crystals

The mechanoluminescence appears in the elastic, plastic and fracture regions of γ- and X-irradiated KCl and NaCl crystals. A linear relation is found between the mechanoluminescence intensity and the newly created dislocations. Four models are proposed for the mechanoluminescence excitation during the movement of dislocations. These models are: dislocation unpinning model, dislocation interaction model, dislocation defect stripping model, and dislocation innihilation model. The dislocation annihilation model seems to be a dominating process for the M.L. excitation in γ- and X-irradiated alkali halide crystals.     

Long Time Behaviour of Marginally Stable Magnetomodulational Perturbation

The long time behaviour of magnetomodulational perturbation has been investigated by using multiple time scale perturbation method. If the perturbation field is purely potential, it is found that unlike ordinary modulational unstability the magnetomolulational instability persists in the nonlinear stage of evolution. The exact analytical solution obtained for the marginally stable mode of the linear theory exhibits explosively unstable behaviour in the slow time scale. When both potential and solenoidal components of perturbation are present the transverse exerts a stabilising influence. Different kinds of long time behaviour may occur as medicated by the results of the numerical integration of the coupled nonlinear evolution equations for the Langmuir and transverse fields.     

Residual resistivity in Ni-Fe-Cr/V alloys and the two-current model

The resistivity of a large number of Ni-Fe-Cr/V alloys has been measured at 77 K. An attempt has been made to explain the concentration dependence of resistivity in the light of Mott’s two-current model. It is seen that contrary to earlier observation, the model is applicable to a larger range of concentration for the Ni-Fe-Cr series. Appreciable deviation from the model starts for Fe concentration exceeding about 15 at. % and Cr about 7 to 8 at. %. However, for similar concentration range in Ni-Fe-V series, disagreement between the experimental and theoretical results is more pronounced.     

Ag2O as nucleating agent in the crystallization of superconducting phase in Bi2Sr2Ca4Cu5γ glass composition

The nucleating action of silver oxide (1 mol% Ag₂O) in the crystallization of superconducting phase in Bi₂Sr₂Ca₄Cu₅O_γ system is quite remarkable. The characteristics of these glass ceramics are found to depend chiefly upon the formation conditions of the initial glass composition and a subsequent phase separation. We observe from the SEM studies the evidence of highly textured growth. The presence of long platelet and square-like platelet-type particles could be explained on the basis of an orientation effect. Besides being influencing the structural properties markedly, the nucleating agent also affects the physical properties, in particular, the normal state resistivity (). The above effects result in broadening of X-ray diffraction lines and a change in slope, in the normal state region (190–220 K) of (T) plots. Out of the three procedures used to fit the (T) data, the usual linear fit (χT) does not work out at all over the temperature range 140–300 K. On the other hand non-linear fits, χTⁿ (n=0.5) and the piece-wise linear fits (140–200 K and 220–300 K) work out much better. These results are interpreted on the basis of a possible intergrowth of two superconducting phases.     

New qualitative colour reaction for the identification of copper(I) compounds and complexes

The colour reaction of copper(I) salts and complexes, in sulphuric acid medium, with ferricyanide and ammonia, has been used for the general identification of cuprous compounds. A sulphuric acid solution of Cu(I) compound, when treated with a dilute ferricyanide solution in the presence of ammonia, gives a salmon-pink, red-pink, pink-purple or purple colour or precipitate, characteristic of copper(I). Copper(II) compounds fail to give a positive response. The reaction also forms the basis of a test for ammonium ion and differentiation between ferrocyanide and ferricyanide. The preparation of the copper(I) complex of 1-allyl-2-tetrazoline-5-thione is described.     

The distribution of205Tl proton hole states and estimation of the root mean square radii of206Pb and208Pb from their charge distributions

The fragmentations of the 3s _1/2, 2d _3/2, 2d _5/2 and 1.h _11/2 proton states were deduced using the hole-core coupling model calculation and compared with recent²⁰⁶Pb ( \(\vec d\) ,³He) reaction data. The energies of the proton fragments carrying the main shell-model strengths were used to deduce the radial wave functions of²⁰⁵T1 and²⁰⁷Tl that give rise to charge distributions of these nuclei. From their respective charge distributions, root mean square radii of²⁰⁶Pb and²⁰⁸Pb were extracted.     

Nickel-catalyzed coupling of aryl iodides with aromatic aldehydes: chemoselective synthesis of ketones

Aryl iodides (ArI) couple with aryl aldehydes (Ar'CHO) in the presence of Ni(dppe)Br(2) and Zn to give the corresponding biaryl ketones (ArCOAr'). The use of a bidentate phosphine complex is critical to the success of this catalytic reaction. The reaction provides a new procedure for the synthesis of various functionalized biaryl ketones.     

Extraction and chemical investigation of jute (Corchorus olitorius,Linn.) seed protein

Studies were made on the protein solubility of deoiled jute (Corchorus olitorius, Linn.) seed in aqueous solution over various pHs and in different concentrations of NaCl at pH 8.0. Chemical analysis of the seed protein showed 16 amino acids, of which 9 were essential. Gel filtration on Sephadex G-200 revealed the presence of four components, and their molecular weights were determined by two standard methods. Extractable jute seed proteins in salt solution were separated into six fractions electrophoretically (SDS-PAGE). The molecular weights of the six fractions were found to be 118,000; 103,000; 96,000; 67,500; 48,500; and 15,000.