• Volume 13, Issue 2

      August 1979,   pages  97-204

    • On the Maxwell-Boltzmann statistical distribution function of an ideal gaseous assembly in mass motion

      T M Karade K G Pangarkar

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      The invariance of the Maxwell-Boltzmann statistical distribution function has been established using Hsu’s space-light transformations. The transformations of temperature and heat turn out to be the same as given by Ott, contradicting Planck-Einstein’s views regarding their transformation. Incidently the invariance of entropy is obtained.

    • Temperature corresponding to ultrasonic velocity maximum studies in aqueous solutions

      C Murali Krishna B Ramachandra Reddy N Prabhakara Rao K C Reddy

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      Ultrasonic velocities in aqueous solutions of acetamide, dimethyl urea andβ-alanine at different concentrations in the temperature range of about 60°C to 80°C have been measured using an interferometer technique with an accuracy of ±0.003%. The temperature corresponding to velocity maximum at different concentrations is evaluated with an accuracy of ±0.2°C. The results are discussed in the light of the structure-breaking property of these substances in water.

    • Raman and infrared intensity analysis of CHCl3 and CDCl3

      Pratibha Naik V A Padma N Rajeshwara Rao

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      Raman and infrared intensity analysis of CHCl3 is attempted to determine the bond polarisability derivatives and bond dipole moments and their derivatives respectively, on lines expained in our earlier papers.

    • Electrical and thermal conductivity of soft solder at low temperatures

      Y Hariharan M P Janawadkar T S Radhakrishnan

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      The electrical resistivity of soft solder (Pb0.28Sn0.72) has been measured in the temperature range 4.2 K to 300 K. The ‘alloy’ becomes electrically superconducting at a temperature of 6.9 K. Above this, in the entire temperature range, the resistivity could be described, apart from the residual resistivity, by the weighted average of the resistivities of the individual constituents which are derived from the Bloch-Grüneisen relation. The results are in accordance with the phase diagram, which shows a co-existence of two phases in almost the entire range of concentration of the Pb-Sn binary system. It has been shown that the thermal conductivity data on soft solder as well as on Pb0.7Sn0.3, both taken from literature, could be interpreted on the same basis, below and above the ‘superconducting transition temperature’. Recent results on other Pb-Sn systems are discussed in the light of this interpretation.

    • Lattice thermal expansion of cesium plumbo chloride

      J Sadanandam G Jayasagar S V Suryanarayana

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      The temperature variation of the lattice parameter of CsPbCl3 in the cubic phase has been studied by x-ray method, from a determination of the precision lattice parameter at various temperatures, ranging from 50°C to 400°C. The coefficient of thermal expansion of CsPbCl3 can be expressed by the quadratic equation,αT = 21.6 × 10−6 + 2.44 × 10−9T + 5.90 × 10−11T2.

    • Superconducting transition temperature for semimetals like bismuth

      S Srinivasan P Bhattacharyya Sudhanshu S Jha

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      The superconducting transition temperatureTc for semimetals like bismuth has been calculated as a function of the densitync of the electron and hole charge carriers. A simplified two-band model for describing the longitudinal dielectric function for such a system has been used in our model calculation. We find that the attractive interaction responsible for the instability of the normal ground state comes not only from the exchange of lattice phonons, but also from the electronhole sound mode, provided the ratio of the averaged hole to electron mass,mh/me ≠ 1. We have compared our theoretical values ofTc(nc) with experimental results for bismuth under hydrostatic pressure, and find reasonable agreement ifmh/me is assumed to have a value which is only slightly larger than that at atmospheric pressures. A linear variation of the negative band gap as a function of pressure has been assumed for the sake of this comparison.

    • NQR frequencies in polycrystalline samples and their correlation with σ and ki values

      D V Ramanamurti P Venkatacharyulu D Premaswarup

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      NQR frequencies are studied in 6 compounds at 77°K and room temperature. The frequencies of the substituted chlorobenzene derivatives are compared with values calculated using the σ andk values of Hammett and Biedenkapp and Weiss respectively. The poor agreement between observed and calculated values is ascribed to the presence of two or more substituent groups other than chlorine and the consequent interaction between them. The poor agreement with Nagarajan’s equation at room temperature is ascribed to the increase in temperature. The σ andk values for the orthobenzamide group are estimated from the observed frequencies as 0.275 and 0.369 respectively.

    • TheB2Σ-X2Σ system of the CaF molecule

      Ram Samujh Ram S B Rai K N Upadhya

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      The spectrum of theB2Σ-X2Σ system of the CaF molecule has been photographed in the second order of a 10.6 m concave grating spectrograph with 0.33 Å/mm dispersion. The rotational structure of the (0, 0) and (1, 0) bands has been analysed and the precise molecular constants have been obtained. Using the constants so determined the band origins of a large number of bands with 0 <v′,v″ < 10 have been calculated and used to obtain the accurate vibrational constants forB andX states and these are presented.

    • 4He and soft-core radial function

      S Srinivasa Raghavan

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      The suitability of a soft-core radial wave function in4He calculations is tested by computing the charge form factor of the alpha particle. The free parameter in the radial function is fixed in a photo-disintegration calculation. The results show that the soft-core function is suitable and the ground state of4He may be described reasonably well if a suitable potential model is used with it.

    • Mixing of meson isosinglets

      D Mishra C V Sastry

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      The mixing angles for the vector and pseudoscalar meson isosinglets are obtained in a non-relativistic quark model. Schwinger-type mass relations are also obtained for SU(4) and SU(5). Quark contents of different meson isosinglets are computed which agree well with similar estimation of Maki and co-workers and Boal.

    • On the problem of constraints in minimally coupled relativistic wave equations for particles of unique mass

      M Seetharaman T R Govindarajan P M Mathews

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      We study the problem of a possible change in the number of constraints in linear relativistic wave equations (-μμ+m)ψ=0 for particles of unique mass, on introduction of minimal coupling to an external electromagnetic field. Complementing our earlier work in which we obtained conditions for non-loss of constraints in equations characterised by the minimalβ-algebraβ05 =β03 we derive here the conditions for such theories not to generate more constraints than in the free case. The results are illustrated by considering specific equations and a fallacy in certain conclusions of Kobayashi and Shamaly on this problem is pointed out.

    • General relations among observables in neutral-current phenomena mediated by one or twoZ bosons

      M K Parida G Rajasekaran

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      Ifμ-e universality is assumed, there are 17 neutral-current parameters of current experimental interest, including the parity-violating nuclear force sector. We deduce the general relations among these parameters implied by gauge models. In single-Z boson models, there are 10 relations, while two-boson models lead to 4 relations. Ifμ-e universality is abandoned, the number of parameters increases to 31, while the number of relations becomes 21 in single-boson models and 12 in two-boson models. We derive all these relations.

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