NISCAIR Online Periodicals Repository Collection: IJPAP Vol.42(11) [November 2004]

Microwave dielectric relaxation study of binary mixtures of cyclohexylamine with acetophenone and p-chloroacetophenone in dilute solutions of benzene

Fri, 29 Oct 2004 22:58:59 GMT

Title: Microwave dielectric relaxation study of binary mixtures of cyclohexylamine with acetophenone and p-chloroacetophenone in dilute solutions of benzene

Authors: Gupta, K K; Bansal, A K; Singh, P J; Sharma, K S

Abstract: Static permittivity at 100 kHz, complex permittivity at 8.93 GHz and high frequency permittivity at frequency of the D-lines of sodium of cyclohexylamine (CHA), acetophenone (ACT), p-chloroacetophenone (PCLA) and for the binary mixtures of CHA+ACT and CHA+PCLA have been measured in dilute solutions of benzene at different temperatures. The measured values of permittivity and dielectric loss have been used to evaluate relaxation times [₀, (1) and (2)], dipole moment (), distribution parameter () and thermodynamical parameters like molar free energy of activation (F_Î), molar enthalpy of activation (H_Î) and molar entropy of activation (S_Î). The relaxation times of binary mixture compositions are consistent with the computed values obtained from various theoretical methods. Present study suggests the existence of both the intramolecular and overall orientation in both the binary mixtures. Formation of complexes is noticed in 1:1 binary mixture of CHA+PCLA.

Page(s): 849-853

Application of pseudopotential to III-V semiconductor compounds

Fri, 29 Oct 2004 22:58:59 GMT

Title: Application of pseudopotential to III-V semiconductor compounds

Authors: Jivani, A R; Gajjar, P N; Jani, A R

Abstract: The recently proposed model potential which includes covalent correction terms, is employed to calculate total energy, energy band gap at Jones-zone face and bulk modulus of GaP, GaAs, GaSb, InP, InAs and InSb. The ratio of the covalent bonding term E_cov to the second order term E₂ confirms the essentiality of higher order correction for zinc blende-type crystals. The calculated numerical results for the total energy, energy band gap at Jones-zone face and bulk modulus of these compounds are in good agreement with the experimental data than other such theoretical findings.

Page(s): 833-836

Excess volumes, deviation in viscosities and compressibilities of binary mixtures consisting of morpholine, piperidine with methanol and pyridine at different temperatures

Fri, 29 Oct 2004 22:58:59 GMT

Title: Excess volumes, deviation in viscosities and compressibilities of binary mixtures consisting of morpholine, piperidine with methanol and pyridine at different temperatures

Authors: Rao, G V Rama; Sarma, A Viswanatha; Rambabu, C

Abstract: The density, viscosity and ultrasonic velocity in binary liquid mixtures of morpholin, piperidine with methanol and pyridine have been determined at different temperatures from 303.15 to 318.15K over the whole composition range. These data have been utilized to estimate the excess volumes V^E, deviation in viscosity (), deviation in adiabatic compressibility (_ad)and excess intermolecular free length (L_f^E) at the above temperatures. The excess values have been found to be useful in estimating the strength of the interactions in the liquid mixtures. Analysis of these parameters indicates that there are intermolecular interactions among components of the binary mixtures that lead to the possible hydrogen bond formation (of the type N… H-O and N…H-N) between unlike molecules.

Page(s): 820-826

Interferometry based security hologram readable with an encoded key hologram

Fri, 29 Oct 2004 22:58:59 GMT

Title: Interferometry based security hologram readable with an encoded key hologram

Authors: Aggarwal, A K; Kaura, Sushil K; Sharma, Amit K; Kumar, Raj; Chhachhia, D P

Abstract: A simple and cost-effective method for making security holograms has been presented, which incorporates holographic interferometry as verification feature in addition to spatially separated sharp focus spots. When the security hologram is illuminated with decoding reconstructing beam generated from an encoded key hologram, two spatially separated sharp focus spots emerge at the predefined positions and can be read through a photoelectric detector array. In addition, these focused spots upon divergence in longitudinal direction further generate specific kind of interferometric fringe patterns of random profile contained in them, which are suitable for further visual inspection. These machine-readable and visual verifiable features can be used for better counterfeit-resistant security codes in embossed holograms. Recording schemes for the formation of such security holograms and typical experimental results have been presented.

Page(s): 816-819