025092   SEENAPPA L, MANJUNATHA H C, SRIDHAR K N, HANUMANTHARAYAPPA C (Physics Dep, Government Coll for Women, Kolar - 563 101, Email: manjunathhc@rediffmail.com) : Gamma, X-ray and neutron shielding properties of polymer concretes. Indian J Pure Appl Phys 2018, 56(5), 383-91.

We have studied the X-ray and gamma radiation shielding parameters such as mass attenuation coefficient, linear attenuation coefficient, half value layer, tenth value layer, effective atomic numbers, electron density, exposure buildup factors, relative dose, dose rate and specific gamma ray constant in some polymer based concretes such as sulfur polymer concrete, barium polymer concrete, calcium polymer concrete, flourine polymer concrete, chlorine polymer concrete and germanium polymer concrete. The neutron shielding properties such as coherent neutron scattering length, incoherent neutron scattering lengths, coherent neutron scattering cross section, incoherent neutron scattering cross sections, total neutron scattering cross section and neutron absorption cross sections in the polymer concretes have been studied. The shielding properties among the studied different polymer concretes have been compared. From the detail study, it is clear that barium polymer concrete is good absorber for X-ray, gamma radiation and neutron. The attenuation parameters for neutron are large for chlorine polymer concrete. Hence, we suggest barium polymer concrete and chlorine polymer concrete are the best shielding materials for X-ray, gamma and neutrons.

12 illus, 3 table, 46 ref

025091   REDA M S, MOHAMMAD K A, EL-FARAMAWY S M (Research and Development Dep, Radiometry Laboratory, Giza, Egypt, Email: egyreda@outlook.com) : Construction and characterization of a phototherapy radiometer for optical radiation measurements. Indian J Pure Appl Phys 2018, 56(5), 379-82.

It is necessary to measure the irradiance levels to evaluate the effective dose delivered to the neonate from phototherapy devices. For such purpose, a broadband phototherapy radiometer has been used for measuring these phototherapy irradiance doses of plurality types of phototherapy sources. A phototherapy radiometer has been designed and during the construction its optical characteristics has been tested in collaboration between the National Institute of Standards in Egypt (NIS) and Department of Research And Development, Medical Engineering Group (MEG) Company. The most parameters required to characterize the performance of radiometer are the responsivity and uniformity. Then the present radiometer has been compared to other two available portable phototherapy radiometers in irradiance levels measurement. The calibration has been settled and the expanded uncertainties has been calculated according to the Guide to the expression of uncertainty in measurement (GUM) at coverage factor k = 2. The designed radiometer has responsivity range 415-495 nm with FWHM 35 nm which covers the phototherapy blue band. The radiometer results output summarized as; quantum efficiency is 84 %, the uniformity 72 % and measuring irradiance range 100-2500 µW.cm^-2.

3 illus, 13 ref

025090   PATHAK A K, SINGH V K (Applied Physics Dep, Indian Institute of Technology (Indian School of Mines), Dhanbad - 826 004, Email: vksingh@iitism.ac.in) : Investigations on sensing properties of tapered photonic crystal fiber refractive index sensor. Indian J Pure Appl Phys 2018, 56(5), 373-8.

In present study a multi-mode fiber (MMF) stubbed tapered photonic crystal fiber (PCF) has been fabricated for refractive index and temperature sensing. The sensing probe has been formed by stubbing MMF and tapered PCF with varying tapering length, between two standard single-mode fibers (SMF). It has been observed from the experiment that the tapering of PCF and its tapering length affect the sensitivity of proposed sensor. Maximum sensitivity of 1891 µW/RIU and 900 µW/RIU has been achieved for single and dual point tapered PCF, respectively and a good linear response for high refractive indices has been obtained by measuring the optical output powers. The fabricated sensor has also been characterized for temperature sensing. The temperature sensitivity of 30 nW/°C and 19 nW/°C has also been measured from both single and dual point tapered PCF, respectively, for the temperature variation from 30 °C to 80 °C at the interval of 5 °C.

6 illus, 1 table, 33 ref

025088   YAJNHESWARAN B, RAO S (Applied Mechanics and Hydraulics Dep, NITKSurathkal, Karnataka, Email: yajneshholla@gmail.com) : Effect of stiffness on performance of a diaphragm wall with irregular configuration. Indian J Geo-Mar Sci 2018, 47(5), 1058-64.

Present study investigates the influnces of the stiffness on the performance of a lateraly loaded R.C.C diaphragm wall and an inter-comparison has been made between the actual and compound sections by modelling the wall using Plaxis 3D software. Displacement and bending moment are found out for diaphragm walls and results are compared with the actual diaphragm wall section having 1.1 m thick.The study concludes that when two sections of different stiffness are coupled to form a single section, the stiffer member takes higher bending moment and the magnitude depends the stiffness of the thinner member.

13 illus, 7 tables, 7 ref

025066   KATHIRESAN K, ELANGOVAN P, SARAVANAKUMAAR M S S (Physics Dep, Saraswathi Narayanan Coll (Autonomous), Madurai-625 022, Email: 2ssaravanakumar@gmail.com) : Structural effects of tungsten oxide electro-catalyst towards high stable CO tolerance mechanism. Asian J Chem 2018, 30(3), 567-71.

In this work, a cost effective, facile and rational synthesis of two different nanostructures including nanosphere shaped and nanorod sized tungsten oxide nanomaterials. The prepared nanoparticles were characterized by powder X-ray diffraction, scanning and transmission electron microscopic analyses, energy dispersive spectroscopy and Raman spectroscopy. The XRD result confirms that the nanoparticles have a polycrystalline nature with well-developed monoclinic crystalline structure. The microscopic images evidently confirm the nanosphere shaped and nanorods sized WO₃ samples. Further the purity and stoichiometry amount of chemical compositions were confirmed by the EDS spectra. The modes of vibrations of the WO₃ nanoparticles were identified by Raman spectroscopy. From these structural investigations, it is evidently showing that the morphologies of the final products can be tuned via synthesis process. In addition, the WO₃ nanosphere exhibited excellent long-term durability and CO tolerance against the high quality Pt/C catalyst. To our best of knowledge, this is the first report of the use of WO₃ nanocrystals that act as CO₂ tolerance catalysts with high stability. The enhanced activity of the WO₃ nanosphere is due mainly to the higher structural openness in WO₃ and this makes the WO₃ nanosphere a good candidate for high-performance non-precious metal-based electrocatalysts with low cost and high efficiency for electrochemical energy conversion.

6 illus, 38 ref

025114   JIANJUN X, LING H (Jilin Univ, Changchun- 130 026, China, Email: tiantianhappy365@126.com) : A target imaging method of multiple-input-multiple-output ground penetrating radar-based on direction of arrival estimation. Curr Sci 2018, 114(5), 1014-23.

In this study we consider imaging of the multipleinput-multiple-output ground penetrating radar (MIMO-GPR) system, and analyse the effect and accuracy of the estimation for target echo arrival upon direction of arrival (DOA) in the three beam-forming algorithms, i.e. least square, Capon algorithm and amplitude phase estimation. We propose a method of multi-antenna GPR target imaging based on the DOA estimation. This method, to perform the target imaging, makes combined use of DOA estimation of target echo signal in MIMO array and array spatial observation information. By spatial scanning for the imaging points, the target is localized and the reflection intensity is estimated from the weighted integral of each estimated DOA amplitude value at the imaging point. This method, with simpler practice, less data observation frequency and more efficient calculation, can speed up the target detection measurement and improve the data interpretation efficiency.

20 illus, 22 ref

025089   MENON J, MUDGAL B V (Centre for Water Resources, Anna Univ, Chennai- 600 025, Email: jailakshmim@yahoo.co.in) : Experimental determination of contraction coefficient and velocity coefficient for radial gates with elliptical lips. Sadhana 2018, 43(3), 61.

Radial gates are widely used to control the flow in irrigation channels and spillways. Radial gates require lower hoisting force and have better discharge characteristics in partial gate openings. The accurate discharge measurement through a radial gate is a challenging problem especially in submerged flow conditions. The coefficient of contraction C_c is an important parameter for accurate discharge measurement in open channels. In this study, an attempt has been made to determine the coefficient of contraction C_c and velocity coefficient C_v for radial gates both for free flow and submerged flow conditions. The flow emanating from a gate is similar to the wall jet emerging from a nozzle. The C_c and C_v values under free and submerged flow conditions are obtained from the measured jet velocity and the discharge. The coefficient of discharge values under submerged flow conditions show large variations with submergence and hence discharge characteristics needs to be improved for better control of flow. Hence, experiments are conducted so as to improve the discharge characteristics by modifying the exit geometry of the radial gate by attaching a quarter of an elliptical lip. Three different geometries of elliptical lips were attempted and the results show reasonable increase in the contraction coefficient.

13 illus, 1 table, 23 ref

025087   CHOUDHURY B S, MONDAL H S, CHATTERJEE D (Basic and Applied Sciences Dep, Indian Institute of Engineering, Howrah- 711 103, Email: binayak12@yahoo.co.in) : Some dynamical aspects of interacting quintessence model. Pramana – J Phys 2018, 90(4), 55.

In this paper, we consider a particular form of coupling, namely B = σ (ρ˙_m − ˙ρ_φ) in spatially flat (k = 0) Friedmann–Lemaitre–Robertson–Walker (FLRW) space–time. We perform phase-space analysis for this interacting quintessence (dark energy) and dark matter model for different numerical values of parameters. We also show the phase-space analysis for the ‘best-fit Universe’ or concordance model. In our analysis, we observe the existence of late-time scaling attractors.

3 illus, 2 tables, 15 ref

025086   ILANGO M S, RAMASESHA S K (Divecha Centre for Climate Change, Indian Institute of Science, Bengaluru- 560 012, Email: sheela.ramasesha@gmail.com) : Novel patterning of CdS/CdTe thin film with back contacts for photovoltaic application. Pramana – J Phys 2018, 90(4), 53.

The heterostructure of patterned CdS/CdTe thin films with back contact have been devised with electron beam lithography and fabricated using sputter deposition technique. The metallic contacts for n-CdS and p-CdTe are patterned such that both are placed at the bottom of the cell. This avoids losses due to contact shading and increases absorption in the window layer. Patterning of the device surface helps in increasing the junction area which can modulate the absorption of more number of photons due to total internal reflection. Computing the surface area between a planar and a patterned device has revealed 133 % increase in the junction area. The physical and optical properties of the sputter-deposited CdS/CdTe layers are also presented. J–V characteristics of the solar cell showed the fill factor to be 25.9 %, open circuit voltage to be 17 mV and short-circuit current density to be 113.68 A/m². The increase in surface area is directly related to the increase in the short circuit current of the photovoltaic cell, which is observed from the results of simulated model in Atlas/Silvaco.

9 illus, 30 ref

025085   JANNAT S, MAMUN A A (Physics Dep, Jahangirnagar Univ, Dhaka, Bangladesh, Email: saudiajannat@gmail.com) : Nucleus-acoustic shock waves in white dwarfs. Pramana – J Phys 2018, 90(4), 51.

The nucleus-acoustic shock waves (NASWs) propagating in a white dwarf plasma system, which contain non-relativistically or ultrarelativistically degenerate electrons, non-relativistically degenerate, viscous fluid of light nuclei, and immobile nuclei of heavy elements, have been theoretically investigated. We have used the reductive perturbation method, which is valid for small but finite-amplitude NASWs to derive the Burgers equation. The NASWs are, in fact, associated with the nucleus-acoustic (NA) waves in which the inertia is provided by the light nuclei, and restoring force is provided by the degenerate pressure of electrons. On the other hand, the stationary heavy nuclei participate only in maintaining the background charge neutrality condition at equilibrium. It is found that the viscous force acting in the fluid of light nuclei is a source of dissipation, and is responsible for the formation of NASWs. It is also observed that the basic features (polarity, amplitude, width, etc.) of the NASWs are significantly modified by the presence of heavy nuclei, and that NASWs are formed with either positive or negative potential depending on the values of the charge density of the heavy nuclei. The basic properties are also found to be significantly modified by the effects of ultrarelativistically degenerate electrons. The implications of our results in white dwarfs are briefly discussed.

3 illus, 1 table, 22 ref

025084   LAHA U, MAJUMDER M, BHOI J (Physics Dep, National Institute of Technology, Jamshedpur- 831 014, Email: ujjwal.laha@gmail.com) : Volterra integral equation-factorisation method and nucleus-nucleus elastic scattering. Pramana – J Phys 2018, 90(4), 48.

An approximate solution for the nuclear Hulthén plus atomic Hulthén potentials is constructed by solving the associated Volterra integral equation by series substitution method. Within the framework of supersymmetry-inspired factorisation method, this solution is exploited to construct higher partial wave interactions. The merit of our approach is examined by computing elastic scattering phases of the α−α system by the judicious use of phase function method. Reasonable agreements in phase shifts are obtained with standard data.

3 illus, 33 ref

025083   ALI M S, RAY A, RAJA W, BANDYOPADHYAY A, NAIK V, POLLEY A, CHAKRABARTI A (Variable Energy Cyclotron Centre, Kolkata- 700 064, Email: sabirbarc@gmail.com) : Development of a collinear laser spectrometer facility at VECC: First test result. Pramana – J Phys 2018, 90(4), 47.

We report here the development of collinear laser spectroscopy (CLS) system at VECC for the study of hyperfine spectrum and isotopic shift of stable and unstable isotopes. The facility is first of its kind in the country allowing measurement of hyperfine splitting of atomic levels using atomic beams. The CLS system is installed downstream of the focal plane of the existing isotope separator online (ISOL) facility at VECC and is recently commissioned by successfully resolving the fluorescence spectrum of the hyperfine levels in 85,87 Rb. The atomic beams of Rb were produced by charge exchange of 8 keV Rb ion beam which were produced, extracted and transported to the charge exchange cell using the ion sources, extractor and the beam-line magnets of the ISOL facility. The laser propagating opposite to the ion/atom beam direction was allowed to interact with the atom beam and fluorescence spectrum was recorded. The experimental set-up and the experiment conducted are reported in detail. The measures needed to be carried out for improving the sensitivity to a level necessary for studying short-lived exotic nuclei have also been discussed.

5 illus, 2 tables, 26 ref

025082   SAHA U, DEVAN K, BACHCHAN A, PANDIKUMAR G, GANESAN S (Homi Bhabha National Institue, Kalpakkam- 603 102, Email: uttiyoarnabsaha@gmail.com) : Neutron radiation damage studies in the structural materials of a 500 MWe fast breeder reactor using DPA cross-sections from ENDF/B-VII.1. Pramana – J Phys 2018, 90(4), 46.

The radiation damage in the structural materials of a 500 MWe Indian prototype fast breeder reactor (PFBR) is re-assessed by computing the neutron displacement per atom (dpa) cross-sections from the recent nuclear data library evaluated by the USA, ENDF/B-VII.1, wherein revisions were taken place in the new evaluations of basic nuclear data because of using the state-of-the-art neutron cross-section experiments, nuclear model-based predictions and modern data evaluation techniques. An indigenous computer code, computation of radiation damage (CRaD), is developed at our centre to compute primary-knock-on atom (PKA) spectra and displacement cross-sections of materials both in point-wise and any chosen group structure from the evaluated nuclear data libraries. The new radiation damage model, athermal recombination-corrected displacement per atom (arc-dpa), developed based on molecular dynamics simulations is also incorporated in our study. This work is the result of our earlier initiatives to overcome some of the limitations experienced while using codes like RECOIL, SPECTER and NJOY 2016, to estimate radiation damage. Agreement of CRaD results with other codes and ASTM standard for Fe dpa cross-section is found good. The present estimate of total dpa in D-9 steel of PFBR necessitates renormalisation of experimental correlations of dpa and radiation damage to ensure consistency of damage prediction with ENDF/B-VII.1 library.

13 illus, 4 tables, 35 ref

025081   DU Z, TIAN B, XIE X, CHAI J, WU X (School of Science, Beijing University of Posts and Telecommunications, Beijing- 100876, China, Email: tian_bupt@163.com) : Bäcklund transformation and soliton solutions in terms of the Wronskian for the Kadomtsev-Petviashvili-based system in fluid dynamics. Pramana – J Phys 2018, 90(4), 45.

In this paper, investigation is made on a Kadomtsev–Petviashvili-based system, which can be seen in fluid dynamics, biology and plasma physics. Based on the Hirota method, bilinear form and Bäcklund transformation (BT) are derived. N-soliton solutions in terms of the Wronskian are constructed, and it can be verified that the Nsoliton solutions in terms of the Wronskian satisfy the bilinear form and Bäcklund transformation. Through the N-soliton solutions in terms of the Wronskian, we graphically obtain the kink-dark-like solitons and parallel solitons, which keep their shapes and velocities unchanged during the propagation.

2 illus, 32 ref

025080   MALLIGAVATHY M, IYYAPUSHPAM S, NISHANTHI S T, PADIYAN D P (Physics Dep, Manonmaniam Sundaranar Univ, Tirunelveli- 627 012, Email: malligavathy2017@gmail.com) : Role of hydrothermal temperature on crystallinity, photoluminescence, photocatalytic and gas sensing properties of TiO₂ nanoparticles. Pramana – J Phys 2018, 90(4), 44.

TiO₂ nanoparticles were synthesised by hydrothermal method. The degree of crystallinity and phase purity were confirmed from the Raman spectra and X-ray diffraction. By increasing the hydrothermal temperature, crystallinity and AC conductivity of the TiO₂ nanoparticles increase. Nitrogen adsorption–desorption measurements confirmed that the samples were mesoporous with an average pore diameter of 4.4–7.45 nm. Photocatalytic activity of TiO₂ nanoparticles was evaluated and the sample hydrothermally treated at 160 ºC has the highest photocatalytic activity. In gas sensing measurements, sensitivity increases as a function of concentration and the response to ethanol vapour was better compared to other gases for the sample synthesised at 160 ºC.

11 illus, 4 tables, 51 ref

025079   GHOSE S (Physics Dep, Surendra Institute of Engineering & Management, Siliguri- 734 009, Email: mrsghose@gmail.com) : On distinguishing different models of a class of emergent universe solutions. Pramana – J Phys 2018, 90(3), 43.

A specific class of singularity-free cosmological model has recently been considered in light of different observational data such as observed Hubble data, BAO data from luminous red galaxy survey by Slowan digital sky survey (SDSS) and CMB data from WMAP. However, it is observed that only 12–14 data points are used to study the viability of the model in late time. In this paper, we discuss the viability of all the models belonging to the same class of EU in light of union compilation data (SNIa) which consists of over a hundred data points, thus getting a more robust test for viability. More importantly, it is crucial that we can distinguish between the various models proposed in the class of solution obtained. We discuss here why with the present observational data it is difficult to distinguish between all of them. We show that the late-time behaviour of the model is typical to any asymptotically de Sitter model.

3 illus, 1 table, 19 ref

025078   BANERJEE S, GHOSE B (Electronics Dep, Vidyasagar Coll, Kolkata- 700 006, Email: sreyasibanerjee10@gmail.com) : Space-charge solitary waves and double layers in n-type compensated semiconductor quantum plasma. Pramana – J Phys 2018, 90(3), 42.

Using quantum hydrodynamic (QHD) model and standard reductive perturbation method, we have investigated the formation and characteristics of space-charge solitary waves and double layers in n-type compensated drifting semiconductor plasma with varying doping profiles. Through numerical analysis, it is shown that the structures of space-charge solitary waves and double layers depend significantly on electron drift and compensation parameter which measures a comparative proportion of the donor, acceptor and intrinsic ion concentrations.

5 illus, 35 ref

025077   ALI B M, AL-ABYAD M, SEDDIK U, EL-KAMEESY S U, DITROI F, TAKACS S, TARKANYI S (Physics Dep, Nuclear Research Centre, Cairo- 13759, Email: alabyad_m@yahoo.com) : Activation cross-section data for α-particle-induced nuclear reactions on natural vanadium for practical applications. Pramana – J Phys 2018, 90(3), 41.

Excitation functions for α-induced reactions on natural vanadium were measured in the energy range up to 20 MeV. The stacked-foil activation technique was used. The experimental results were compared with the theoretical calculations using EMPIRE-3.1, EMPIRE-3.2.2 and TENDL 2015, and with earlier experimental results. Thick target yields were calculated for the production of ⁵⁴Mn and for the associated impurity ⁵²Mn.

7 illus, 3 tables, 45 ref

025076   GOSWAMI P (Physics Dep, DB College, University of Delhi, New Delhi- 110 019, Email: physicsgoswami@gmail.com) : Effect of ferromagnetic exchange field on band gap and spin polarisation of graphene on a TMD substrate. Pramana – J Phys 2018, 90(3), 40.

We calculate the electronic band dispersion of graphene monolayer on a two-dimensional transition metal dichalcogenide substrate (GrTMD) around K and K points by taking into account the interplay of the ferromagnetic impurities and the substrate-induced interactions. The latter are (strongly enhanced) intrinsic spin– orbit interaction (SOI), the extrinsic Rashba spin–orbit interaction (RSOI) and the one related to the transfer of the electronic charge from graphene to substrate. We introduce exchange field (M) in the Hamiltonian to take into account the deposition of magnetic impurities on the graphene surface. The cavalcade of the perturbations yield particle–hole symmetric band dispersion with an effective Zeeman field due to the interplay of the substrate-induced interactions with RSOI as the prime player. Our graphical analysis with extremely low-lying states strongly suggests the following: The GrTMDs, such as graphene on WY₂, exhibit (direct) band-gap narrowing/widening (Moss– Burstein (MB) gap shift) including the increase in spin polarisation (P) at low temperature due to the increase in the exchange field (M) at the Dirac points. The polarisation is found to be electric field tunable as well. Finally, there is anticrossing of non-parabolic bands with opposite spins, the gap closing with same spins, etc. around the Dirac points. A direct electric field control of magnetism at the nanoscale is needed here. The magnetic multiferroics, like BiFeO₃ (BFO), are useful for this purpose due to the coupling between the magnetic and electric order parameters.

7 illus, 1 table, 57 ref

025075   GUO S, MA J, ALSAEDI A (Physics Dep, Lanzhou University of Technology, Lanzhou- 730050, China, Email: hyperchaos@163.com) : Suppression of chaos via control of energy flow. Pramana – J Phys 2018, 90(3), 39.

Continuous energy supply is critical and important to support oscillating behaviour; otherwise, the oscillator will die. For nonlinear and chaotic circuits, enough energy supply is also important to keep electric devices working. In this paper, Hamilton energy is calculated for dimensionless dynamical system (e.g., the chaotic Lorenz system) using Helmholtz’s theorem. The Hamilton energy is considered as a new variable and then the dynamical system is controlled by using the scheme of energy feedback. It is found that chaos can be suppressed even when intermittent feedback scheme is applied. This scheme is effective to control chaos and to stabilise other dynamical systems.

8 illus, 48 ref

025074   JAWAHER K R, INDIRAJITH R, KRISHNAN S, ROBERT R, DAS S J (Physics Dep, Ramakrishna Mission Vivekananda Coll (Autonomous), Chennai- 600 004, Email: skrishnanjp@gmail.com) : Quantum chemical calculations of Cr₂O₃/SnO₂ using density functional theory method. Pramana – J Phys 2018, 90(3), 38.

Quantum chemical calculations have been employed to study the molecular effects produced by Cr₂O₃/SnO₂ optimised structure. The theoretical parameters of the transparent conducting metal oxides were calculated using DFT/B3LYP/LANL2DZ method. The optimised bond parameters such as bond lengths, bond angles and dihedral angles were calculated using the same theory. The non-linear optical property of the title compound was calculated using first-order hyperpolarisability calculation. The calculated HOMO–LUMO analysis explains the charge transfer interaction between the molecule. In addition, MEP and Mulliken atomic charges were also calculated and analysed.

5 illus, 4 tables, 33 ref

025073   LU D-B, SONG Y-L (Mechanical and Electronic Engineering Coll, Nanyang Normal Univ, Nanyang- 473 061, China, Email: yuling985@163.com) : First principles calculations of optical properties of the armchair SiC nanoribbons with O, F and H termination. Pramana – J Phys 2018, 90(3), 37.

Based on density functional theory, we perform first-principles investigations to study the optical properties of the O-, F- and H-terminated SiC nanoribbons with armchair edges (ASiCNRs). By irradiating with an external electromagnetic field, we calculate the dielectric function, reflection spectra, energy loss coefficient and the real part of the conductance. It is demonstrated that the optical constants are sensitive to the low-energy range, different terminal atoms do not make much difference in the shape of the curves of the optical constants for the same-width ASiCNR, and the optical constants of wider nanoribbons usually have higher peaks than that of the narrower ones in low energy range. We hope that our study helps in experimental technology of fabricating high-quality SiC-based nanoscale photoelectric device.

12 illus, 44 ref

025072   ADHIKARI K (Physics Dep, M.B.B. College, Agartala- 799 004, Email: adhikarikalipada@gmail.com) : Effect of three-body transformed Hamiltonian (Ȟ₃) using full connected triple excitation coupled cluster operators on valence ionisation potentials of Cl₂ and F₂ computed via EIP-VUMRCCSDτ scheme. Pramana – J Phys 2018, 90(3), 36.

Valence universal multireference coupled cluster (VUMRCC) method via eigenvalue independent partitioning has been applied to estimate the effect of three-body transformed Hamiltonian (Ȟ3) on ionisation potentials through full connected triple excitations S₃^(1,0). Ȟ₃ is constructed using CCSDT1-A model of Bartlett et al for the ground-state calculation. Contribution of transformed Hamiltonian through full connected triples Ȟ₃S₃^(1,0) involves huge amount of computational operations that is time-consuming. Investigation on Cl₂ and F₂ molecules using cc-pVDZ and cc-pVTZ basis sets shows that the above effect varies from 0.001 eV to around 0.5 eV, suggesting that inclusion of Ȟ₃S₃^(1,0) is essential for highly accurate calculations.

6 illus, 2 tables, 40 ref

025071   SANTHOSH K P, NITHYA C (School of Pure and Applied Physics, Kannur Univ, Payyanur- 670 327, Email: drkpsanthosh@gmail.com) : Theoretical studies on the α decay half-lives of hyper and normal isotopes of Po. Pramana – J Phys 2018, 90(3), 35.

The α decay half-lives of hyper and normal isotopes of Po nuclei are studied in the present work. The inclusion of –N interaction changes the half-life for α decay. The theoretical predictions on the α decay half-lives of normal Po isotopes are compared with experimental results and are seen to be matching well with each other. The neutron shell closure at N = 126 is found to be the same for both normal and hypernuclei. The Geiger–Nuttal (G–N) law for α decay is unaltered in the case of hypernuclei. The hypernuclei will decay into normal nuclei by mesonic or non-mesonic decay modes. Since the half-lives of normal Po nuclei are well within the experimental limits, our theoretical results suggest experimental verification of the α emission from hyper Po nuclei in a cascade process.

2 illus, 2 tables, 46 ref

025070   ZHANG Y (School of Mathematics and Statistics, Hexi Univ, Zhangye- 734 000, China, Email: ywzhang0288@163.com) : Travelling wave solutions of (2+1)-dimensional generalised time-fractional Hirota equation. Pramana – J Phys 2018, 90(3), 34.

In this article, we have developed new exact analytical solutions of a nonlinear evolution equation that appear in mathematical physics, a (2 + 1)-dimensional generalised time-fractional Hirota equation, which describes the wave propagation in an erbium-doped nonlinear fibre with higher-order dispersion. By virtue of the tanh-expansion and complete discrimination system by means of fractional complex transform, travelling wave solutions are derived. Wave interaction for the wave propagation strength and angle of field quantity under the long wave limit are analysed: Bell-shape solitons are found and it is found that the complex transform coefficient in the system affects the direction of the wave propagation, patterns of the soliton interaction, distance and direction.

4 illus, 53 ref

025069   LAI B, HE J (East China Jiaotong Univ, Nanchang- 330100, Email: petey740@126.com) : Dynamic analysis, circuit implementation and passive control of a novel four-dimensional chaotic system with multiscroll attractor and multiple coexisting attractors. Pramana – J Phys 2018, 90(3), 33.

In this paper, we construct a novel 4D autonomous chaotic system with four cross-product nonlinear terms and five equilibria. The multiple coexisting attractors and the multiscroll attractor of the system are numerically investigated. Research results show that the system has various types of multiple attractors, including three strange attractors with a limit cycle, three limit cycles, two strange attractors with a pair of limit cycles, two coexisting strange attractors. By using the passive control theory, a controller is designed for controlling the chaos of the system. Both analytical and numerical studies verify that the designed controller can suppress chaotic motion and stabilise the system at the origin. Moreover, an electronic circuit is presented for implementing the chaotic system.

12 illus, 1 table, 40 ref

025068   ROSHAN M V, SADEGHI H, GHASABIAN M, MAZANDARANI A (Institute for Research in Fundamental Sciences (IPM), Tehran, Iran, Email: mroshan20@yahoo.com) : Neutron energy measurement for practical applications. Pramana – J Phys 2018, 90(3), 30.

Industrial demand for neutrons constrains careful energy measurements. Elastic scattering of monoenergetic α-particles from neutron collision enables neutron energy measurement by calculating the amount of deviation from the position where collision takes place. The neutron numbers with specific energy is obtained by counting the number of α-particles in the corresponding location on the charged particle detector. Monte Carlo simulation and COMSOL Multiphysics 5.2 are used to account for one-to-one collision of neutrons with α-particles.

4 illus, 12 ref

025067   PAL P S, SAHA A, JAYANNAVAR A M (Institute of Physics, Bhubaneswar- 751 005, Email: priyo@iopb.res.in) : Universal fluctuations in orbital diamagnetism. Pramana – J Phys 2018, 90(3), 29.

Bohr–van Leuween theorem has attracted the notice of physicists for more than 100 years. The theorem states about the absence of magnetisation in classical systems in thermal equilibrium. In this paper, we discuss about fluctuations of magnetic moment in classical systems. In recent years, this topic has been investigated intensively and it is not free from controversy. We have considered a system consisting of a single particle moving in a plane. A magnetic field is applied perpendicular to the plane. The system is in contact with a thermal bath. We have considered three cases: (a) particle moving in a homogeneous medium, (b) particle moving in a medium with space-dependent friction and (c) particle moving in a medium with space-dependent temperature. For all the three cases, the average magnetic moment and fluctuations in magnetic moment have been calculated. Average magnetic moment saturates to a finite value in the case of free particle but goes to zero when the particle is confined by a 2D harmonic potential. Fluctuations in magnetic moment shows universal features in the presence of arbitrary friction inhomogeneity. For this case, the system reaches equilibrium asymptotically. In the case of space-dependent temperature profile, the stationary distribution is non-Gibbsian and fluctuations deviate from universal value for the bounded system only.

7 illus, 2 tables, 28 ref

025065   DESHMUKH A R, SHINDE R V, INGOLE S A, PATHAN A W, LOKHANDE M P, SARODE A V, KUMBHARKHANE A C (Swami Ramanand Teerth Marathwada Univ, Nanded- 431 606, Email: akumbharkhane@yahoo.co.in) : Dielectric relaxation and hydrogen bonding interaction of solvents using time domain reflectometry technique from 10 MHz to 50 GHz. Indian J Pure Appl Phys 2018, 56(4), 346-52.

Complex permittivity spectra ε*(ν) of nine different solvents have been studied in order to extract information at molecular level. The study covers highly polar organic compounds like water having high polarity index (PI=9.0) to chlorobenzene with low polarity index (PI=0.2) and also for the binary mixture of acetonitril (ACN)-dioxane (Dx) and acrylonitrile (ACRN) –dioxane (Dx). Time domain reflectometry (TDR) has been employed in the frequency region of 10 MHz to 50 GHz at room temperature to obtain various parameters such as complex permittivity ε*(ω), dielectric constant ε₀, high frequency limiting dielectric constant (ε_∞), relaxation amplitude (∆ε) and relaxation time (τ). The values of dielectric parameters obtained have been compared with the literature values. Havriliak-Negami equation has been used to analyze the complex permittivity spectra. The Luzar theory and Kirkwood correlation factor are also applied to extract other dielectric parameters.

13 illus, 3 tables, 21 ref

025064   TAVHARE P, CHAUDHARI A (Physics Dep, Government Vidarbha Institute of Science & Humanities, Amravati- 444 604, Email: ajaychau5@yahoo.com) : Spectroscopic characterization of metal decorated benzene and boron/nitrogen substituted benzene. Indian J Pure Appl Phys 2018, 56(4), 341-5.

This work reports theoretical vibrational spectra of Li, Be and Ti doped benzene using second ordered Møller-Plesset method (MP2) with 6-311++G** basis set. Effect of boron/nitrogen atom substitution on the vibrational frequencies of pristine benzene has also been studied using vibrational spectra obtained from quantum chemical method. Two boron/nitrogen atoms have been substituted for exactly opposite carbon atoms in a benzene ring. An influence of metal doping on the vibrational frequencies of boron/nitrogen substituted benzene complexes has been studied and compared with the metal doped pristine benzene complexes. Vibrational frequencies obtained for the isolated benzene have been significantly altered after metal doping and B/N substitution.

8 illus, 2 tables, 15 ref

025063   SARODE A V, KUMBHARKHANE A C, MEHROTRA S C (Swami Ramanand Teerth Marathwada Univ, Nanded- 431 606, Email: avsarode@gmail.com) : Dynamics and interactions in aqueous polyvinylpyrrolidone (PVP K-30): An approach using dielectric relaxation spectroscopy. Indian J Pure Appl Phy 2018, 56(4), 335-40.

Concentration dependent dielectric relaxation of polyvinylpyrrolidone (PVP) [C₆H₉NO)_n K-30 having molecular weight 40000 gmol^-1 has been studied at temperature 298.15 K using time domain reflectometry (TDR) in the frequency range 10 MHz to 30 GHz. The frequency dependence of the complex dielectric permittivity has been analyzed by the Havriliak-Negami expression. For PVP-water system, the concentration range covers PVP molar concentration of 0.00017 ≤ c / M ≤ 0.00067. Two relaxation processes have been detected for aqueous PVP, therefore, two Debye relaxation model was required for consistent description of the complex dielectric permittivity spectra, ε*(ν). The low frequency relaxation process called β-relaxation has been associated with the rotational motion of PVP molecules in the aqueous medium while the high frequency relaxation called γ-relaxation has been associated with the rotation of free water molecules. The low frequency dispersion of relaxation time τ_β ~ 980 ps attributed to rotational motion of PVP, exhibits a linearly increasing amplitude, ∆ε_β(c) from which an effective dipole moment of μ_eff = 3.43 D was deduced for the PVP molecules. The value is in close agreement with the dipole moment 3.85 D for PVP as reported in literature. The values of dipole moments were used to estimate concentration dependence hydration number (Nhyd) of PVP. Dielectric parameters have been corroborated by the parameters: the molar entropy, and molar free energy for both low and high relaxation processes.

8 illus, 16 ref

025062   INGALE N, CHAUDHARI A (Physics Dep, Government Vidarbha Institute of Science and Humanities, Amravati- 444 604, Email: ajaychau5@yahoo.com) : Spectroscopic analysis of sulphur dioxide adsorbed C₂H₄Ti complex: A first principles study. Indian J Pure Appl Phys 2018, 56(4), 331-4.

Vibrational spectroscopic analysis has been carried out to study the effect of SO₂ gas molecule adsorption on geometrical and electronic properties of C₂H₄Ti complex at MP2 6-311++G** level of theory. Different vibrational modes of C₂H₄Ti complex have been studied before and after adsorption of SO₂ molecule. Two different possible configurations of SO₂ adsorption on C₂H₄Ti complex have been considered to know the minimum energy structure. Significant changes in vibrational frequencies of C₂H₄Ti complex have been observed after SO₂ molecule adsorption. Additional vibrational frequency observed in vibrational spectrum of C₂H₄Ti-SO₂ complex shows strong interaction between SO₂ molecule and the C₂H₄Ti complex. There are no imaginary vibrational frequencies observed in the vibrational spectrum of C₂H₄Ti-SO₂ complex which confirms the stability of a complex.

2 illus, 2 tables, 12 ref

025061   SANGALA B R, SURDI H, DESHMUKH P, RANA G, ACHANTA V G, PRABHU S S (Condensed Matter Physics Dep, Tata Institute of Fundamental Research, Colaba- 400 005, Email: prabhu@tifr.res.in) : Angle tunable trapped mode in a THz metamaterial. Indian J Pure Appl Phys 2018, 56(4), 327-30.

We report trapped mode in Fano-like resonance in a terahertz (THz) metameterial (MM) consisting of a concentric circular and elliptical gold rings on semi-insulating GaAs substrate. We present the finite element method (FEM) based design, electron beam lithography based fabrication and 0.2-2 THz window spectroscopic results. The trapped mode of the MM can be tuned by the angle between the major axis of the ellipse and the polarization of incident THz electric field (maximum amplitude ~100V/m).

3 illus, 36 ref

025060   CHALIKWAR P A, PATHAN A W, DESHMUKH A R, LOKHANDE M P, KUMBHARKHANE A C (Swami Ramanand Teerth Marathwada Univ, Nanded- 431 606, Email: akumbharkhane@yahoo.co.in) : Dielectric relaxation studies in water mixtures of dipropylene glycol using a time domain reflectometry technique. Indian J Pure Appl Phys 2018, 56(4), 321-6.

Complex dielectric permittivity of dipropylene glycol (DPG)-water has been studied by time domain reflectometry technique in the frequency range of 10 MHz to 30 GHz. The measurements have been done at temperature 20 °C, 15 °C and 10 °C and at different volume fractions of dipropylene glycol in water. The dielectric relaxation behaviour of binary mixtures of dipropylene glycol-water has been fitted with Cole-Davidson model having an asymmetric distribution of relaxation time. The dielectric parameters such as static dielectric constant, relaxation time and excess dielectric properties for mixture have been reported here. The molecular interaction between dipropylene glycol and water is discussed using Kirkwood correlation factor (g^eff) and dielectric constant for mixtures. These parameters have been fitted to the Bruggeman mixture formula in the non-linear case.

4 illus, 2 tables, 29 ref

025059   GOPALAKRISHANAN D, SAMPATHKUMAR R (Physics Dep, Sathyabama Institute of Science and Technology, Chennai- 600 119, Email: drrskumar1972@gmail.com) : Time domain dielectric spectroscopic studies of interaction of rat tail tendon collagen with potassium oleate and cetylpyridinium chloride in aqueous acetate buffer solution. Indian J Pure Appl Phys 2018, 56(4), 315-20.

Dielectric relaxation studies of aqueous acetate buffer solutions of rat tail tendon collagen with anionic potassium oleate (PO) and cationic cetylpyridinium chloride (CPC) surfactants at four different temperatures 283, 288, 293 and 298 K as a function of surfactant concentrations have been carried out in the 10 MHz to 30 GHz frequency range using time domain dielectric spectroscopy. Apart from the dominant peak around 14.5 GHz; we have observed a peak close to 2.5 GHz for Collagen - PO complexes, whereas the same is not observed for Collagen– CPC complexes. This is explained on the basis of adsorption behaviour of surfactants on to collagen macromolecules. Further, we assigned the dominant mode at high frequency around 14.5 GHz to bulk water relaxation. The other peak observed for Collagen - PO complexes around 2.5 GHz is attributed to hydration water reorientation of the collagen macromolecules in the presence of surfactant. The relaxation time of bulk water and hydration water was calculated using Single Debye and Cole-Cole method respectively. The activation enthalpy and activation entropy for the dipolar orientation for the collagen-surfactant complexes have been calculated from the Arrhenius plot.

5 illus, 2 tables, 26 ref

025058   SHAIKH M A, ANPAT S M, DONGARE A K, KHIRADE P W, SAYYAD S B (Electronic Science Dep, New Arts, Commerce & Science Coll, Ahmadnagar- 414 001, Email: mudassarshaikh333@gmail.com) : Microwave spectroscopy modelling for geophysical parameter retrieval using synthetic aperture radar (SAR) dataset. Indian J Pure Appl Phys 2018, 56(4), 311-4.

The microwave spectroscopy is an extremely powerful tool for synoptic observation of the object on the earthor planetary bodies. One of the best microwave spectroscopy imaging system is the synthetic aperture radar (SAR) remote sensing. It operates in all weather conditions, though there is change in environmental conditions. In the present study microwave L band SIR-C SAR dataset has been used. The various modellings have been used to classify and analyze the geophysical parameters on the earth or planetary bodies. The modelling makes the process of estimating information beyond the real observation range for data interpretation. In the present paper two most widely used modeling techniques for microwave SAR spectroscopy, i.e., empirical model and an integral equation model (IEM) have been discussed. The aim of the present work is accurate, reliable and skillful measurements of geophysical parameters. In the present work, surface roughness, soil moisture, dielectric constant (ԑ) and backscattering coefficients (σ⁰) etc. geophysical parameters have been measured with the help of the statistical parameter and occurrence plane estimated from the microwave SAR image.

4 illus, 2 tables, 11 ref

025057   KABARA K, WANANJE K, SONSALE R, PADGHANE S, SARODE A (Swami Ramanand Teerth Marathwada Univ, Nanded- 431 606, Email: avsarode@gmail.com) : Relaxation dynamics in crab hemolymph protein: A biophysical approach through dielectric spectroscopy. Indian J Pure Appl Phys 2018, 56(4), 307-10.

Physical properties of biological systems are very complex and often difficult to tune with biological properties. Here we report the physical properties of fresh water crab hemolymph; a fluid analogues to the blood in vertebrates. This may be the first ever attempt in case of crab hemolymph to study dielectric properties such as permittivity (ε') dielectric loss (ε"), static dielectric constant (ε₀) and relaxation time (τ) in order to know the structural properties of hemolymph in the surrounding of water molecules. Time domain reflectometry (TDR) in the frequency region of 10 MHz-30 GHz has been used for this purpose for two concentrations at room temperature. Havriliak – Negami equation is used to obtained complex permittivity spectra. The data obtained using TDR was fitted in two-Debye model. Hemolymph in water surrounding shows two relaxations modes. The low frequency relaxation (β-relaxation) observed around 90 MHz often attributed to the rotation of polar protein molecules in hemolymph and high frequency relaxation (γ-relaxation) observed around 18-20 GHz corresponds to the rotation of pure water molecules. It has been observed that the static dielectric constants as well as both low and high frequency relaxation times are little concentration dependent.

4 illus, 1 table, 13 ref

025056   SHINDE J B, RANDER D N, JADHAV S B, SABNIS S M, JOSHI Y S, KANSE K S (Physics & Electronics Dep, Lal Bahadur Shastri Mahavidyalaya, Dharmabad- 431 809, Email: kskanse@gmail.com) : Dielectric dispersion study of glycol ethers and their binary mixtures with water. Indian J Pure Appl Phys 2018, 56(4), 301-6.

The complex dielectric properties of glycol ethers with water at various concentrations have been measured using Agilent make Precision LCR meter E4980A in the frequency range of 20 Hz to 2 MHz at 25 °C with dielectric liquid test fixture 16452A. The electrical and dielectric properties of the binary mixtures have been represented in terms of complex dielectric function ε* (ω), electrical modulus M* (ω), electrical conductivity σ* (ω).  All these parameters have been used to explain the various processes associated with the electric and dielectric properties of the binary mixtures of glycol ethers inaqueous solutions. The values of static dielectric constant of various concentrations have been reported at 2 MHz frequency. Further the excess dielectric properties for the binary mixtures have been evaluated to investigate the heterogeneous interactions in glycol ether-water molecules.

6 illus, 19 ref

025055   BEHERE S, DESHMUKH B, PATIL S, BEHERE S H (Physics Dep, Dr Babasaheb Ambedkar Marathwada Univ, Aurangabad- 431 004, Email: supriyabehere1987@gmail.com) : Temperature of the disc integrated sunlight from the intensity measurements of rotational lines of the bands of A-X system of CH molecule. Indian J Pure Appl Phys 2018, 56(4), 294-300.

The temperature of the disc integrated sunlight has been calculated by measuring the intensities of 113 rotational lines belonging to the R and P branches of the 0-0, 1-1 and 2-2 bands of the A²Δ_5/2-X²Π_3/2  transition and 0-0 and 1-1 bands of A²Δ_3/2-X ²Π_1/2 transition of a CH molecule. The Fourier transform spectroscopic data has been taken from solar flux Atlas for the visible and near infra-red prepared by Wallace (NSO Technical Report #11-001 2011). The temperature comes out as 3300 ± 121 K, less than the surface temperature of the photosphere of the sun as expected.

5 illus, 7 tables, 35 ref

025054   SENTHILKUMAR P, GANESH T, VINOTH K, SYLVESTER M M, KARUNAKARAN D J S A (Rajah Serfoji Government Coll, Thanjavur- 613 005, Email: tgsastra@gmail.com) : Dielectric dispersion and thermodynamical effect of aqueous morpholine by using picosecond TDR. Indian J Pure Appl Phys 2018, 56(4), 288-93.

The dielectric permittivity parameters, excess characteristic properties, conductivity and thermodynamic properties of binary mixtures morpholine + water have been measured as a function of frequency for various mole fractions. Dielectric dispersion and molecular interactions of morpholine binary mixture depend on concentration and temperature. The results obtained have been used to interpret the nature of solute-solvent interactions. The relaxation process attained in the solution constituents have been related to probable molecular complex formation and its associated behaviours have been discussed. The concentrations have relaxation in a selective frequency region with symmetrical distribution in relaxation times. Additional measurements on aqueous mixtures of morpholine reveal a considerable tendency towards hetero-association. Confirmations of orientated dipole ordering by Kirkwood correlation factors of the mixtures have been assessed. The enthalpy (ΔH), entropy (ΔS) and Gibbs free energy (ΔG) have been calculated for various concentrations and temperature. Thermodynamic parameters depend on concentrations and their relative relaxation processes have been discussed. The interaction and relative dipole ordering are discussed in term of correlation (g^eff) and excess properties (Ɛ^E  and (1/τ)^E.

8 illus, 33 ref

025053   MATHPATI R N, SHINDE S B, RATHOD D G, KANSE K S, JOSHI Y S (Physics & Electronics Dep, Lal Bahadur Shastri Mahavidyalaya, Dharmabad- 431 809, Email: yjosh@rediffmail.com) : Study of dielectric relaxation and hydrogen bonding interaction in binary mixtures of methoxy polyethylene glycol and water. Indian J Pure Appl Phys 2018, 56(4), 282-7.

The complex permittivity spectra of binary mixtures of methoxy polyethylene glycol (Polyethylene glycol monomethylether 350) and water over entire concentrations and at different temperatures have been measured using time domain technique in the frequency range of 10 MHz to 30 GHz. The spectra have been fitted to Cole-Davidson model using non linear least square fit method to obtain the dielectric parameters. The non linear behaviour of dielectric parameters suggest intermolecular interaction among the unlike molecules. Excess properties and Bruggeman factor confirm the contribution of hydrogen bonding interactions among the solute-solvent mixtures. Thermodynamic properties of these binary mixtures are also discussed.

7 illus, 3 tables, 29 ref

025052   WANANJE K H, KABARA K B, SONSALE R P, KANSHETTE M S, SARODE A V (School of Physical Sciences, Swami Ramanand Teerth Marathwada Univ, Nanded- 431 606, Email: avsarode@gmail.com) : Thermo acoustic and optical properties of aqueous polyvinyl pyrrolidone (PVP-40) using spectroscopic techniques. Indian J Pure Appl Phys 2018, 56(4), 276-81.

Present study deals with the investigation of molecular interactions in aqueous polyvinyl pyrrolidone having molecular weight 40,000 (PVP-40) at different temperatures using acoustical and UV-Vis spectroscopic techniques. Ultrasonic velocity (u), density (ρ) and coefficient of viscosity (η) have been measured for aqueous solution of PVP- 40 in the concentration range 0.833-5.00 wt % at frequency 10 MHz. The measurements have been made at eight different temperatures, namely, 283.15, 288.15, 293.15, 298.15, 303.15, 308.15, 313.15, 318.15 and 323.15 K and at atmospheric pressure. The experimental results have been used to calculate various acoustical parameters such as adiabatic compressibility (β), acoustical impedance (Z) free length (L_f) and free volume (V_f), relaxation time (τ), absorption coefficient (α/f²), Rao’s constant (R) and Wada’s constant (W). The variations of these parameters under different conditions of temperature and concentration have been used to discuss the nature and extent of intermolecular interactions between the component molecules. The results have been confirmed using UV-Visible spectroscopy.

11 illus, 33 ref

025051   HUDGE P G, PAWAR R N, WATODE B D, KUMBHARKHANE A C (S R T M Univ, Nanded- 431 606, Email: akumbharkhane@yahoo.co.in) : Dielectric relaxation behaviour of triethylene glycol [TEG]+water mixture as a function of composition and temperature using TDR technique. Indian J Pure Appl Phys 2018, 56(4), 269-75.

The complex dielectric spectra of binary mixture of triethylene glycol [TEG] + water have been carried out at different concentrations and temperatures ( 0 °C, 5 °C, 10 °C, 15 °C, 20 °C and 25 °C ) in the frequency range of 10 MHz to 30 GHz using time domain reflectometry technique. The static dielectric constant (ε₀), relaxation time (τ), Kirkwood correlation factor (g^eff), excess permittivity (ε₀^E ), thermodynamic parameters (activation enthalpy and entropy ) and Bruggeman factor (f_B) have been determined for binary mixtures. The Bruggeman model for the nonlinear case has been fitted to the dielectric data. These dielectric parameters confirm that the intermolecular homogeneous and heterogeneous hydrogen bonding vary significantly with the increase in concentration of the triethylene glycol in water mixtures.

6 illus, 3 tables, 30 ref

025050   KONDA R, CHAUDHARI A (Physics Dep, Government Vidarbha Institute of Science & Humanities, Amravati- 444 604, Email: ajaychau5@yahoo.com) : Vibrational spectra for closoborate and metal doped closoborate using ab initio method. Indian J Pure Appl Phys 2018, 56(4), 265-8.

We have used second order Møller Plesset (MP2) method with 6-311++G** basis set to obtain the ground state geometries along with vibrational spectra of closoborate (B₆H₆) and alkali, alkaline earth and transition metal doped closoborate complexes. Effect of metal doping on vibrational frequencies and geometrical parameters has been studied. The vibrational frequencies of metal doped closoborates have been compared with those for the isolated closoborate. A large shift in vibrational modes of B₆H₆ has been observed upon single and two metal atom doping. The B-B bonds in closoborate get shortened by 0.2 Å after single and two metal atom doping for all the metals. A large change in B-M bond upon second metal atom doping than the first atom doping has been observed for Be and Sc cases where as there is almost no difference in B-Li bond length upon first and second Li atom doping. Stability of these inorganometallic complexes has been confirmed using a gap between highest occupied molecular orbital and lowest unoccupied molecular orbitals.

3 illus, 2 tables, 14 ref

025049   KARTHICK N K, ARIVAZHAGAN G, KANNAN P P, MAHENDRAPRABU A (Physics Dep, Thiagarajar Coll, Madurai- 625 009, Email: arivuganesh@gmail.com) : FTIR spectral studies and dielectric relaxation studies on binary solutions of ethyl acetate with bromobenzene. Indian J Pure Appl Phys 2018, 56(4), 261-4.

FTIR spectroscopic studies have been carried out on the equimolar binary solution of ethyl acetate with bromobenzene. From the studies it has been found that there are possibilities for hydrogen bond formation between hydrogen in bromobenzene and the oxygen in ethyl acetate. Red and blue shifts have been observed in the asymmetric stretching modes of methyl and methylene group, respectively, of ethyl acetate in the binary solution. This may be due to the dissociation of ethyl acetate and/or the hetero-interactions with bromobenzene. Dielectric relaxation studies have been carried out using time domain reflectometry in the frequency range; 10 MHz to 30 GHz at 298 K on the ethyl acetate- bromobenzene binary solutions over the entire composition range. From the corrective Kirkwood correlation factor values it has been inferred that the hetero-interactions present in the solutions are weak in nature.

3 illus, 2 tables, 12 ref

025048   KUMAR P, KUMAR R (Physics Dep, Dr Harisingh Gour Central Univ, Sagar- 470 003, Email: rajneeshipr@gmail.com) : Study of monopole plasma antenna parameters. Indian J Pure Appl Phys 2018, 56(3), 238-47.

This paper is aimed to investigate the plasma antenna parameters to help the optimization of plasma antenna dimensions (length and radius of plasma antenna). Five different configurations of plasma antenna have been simulated with the help of high frequency structure simulator (HFSS 13.0). The observations have been made on variation in antenna parameters like resonance frequency, directivity, gain and radiation pattern with the radius and length of the plasma column. The results of the study indicate that plasma column of radius r < 1.5 cm shows better performance in the sense of directivity and gain than the plasma column of radius r > 0.5 cm. In addition, tunability of the plasma antenna has been studied with respect to the resonance frequencies. Moreover, simulation results have been matched with experimental results, e.g., directivity and radiation patterns, providing more interesting results which cannot be measured due to experimental restrictions.

19 illus, 5 tables, 18 ref

025047   ISLAM M A, HASANUZZAMAN M, RAHIM N A (Malaya Univ, Kuala Lumpur- 59 990, Malaysia, Email: hasan@um.edu.my) : Experimental investigation of on-site degradation of crystalline silicon PV modules under Malaysian climatic condition. Indian J Pure Appl Phys 2018, 56(3), 226-37.

Photovoltaic (PV) power plant capacity is growing very fast in Malaysia. The operating capacity of a PV plant digresses from the installed capacity after several years of operation. The degradation rate of different poly and mono crystalline silicon PV modules due to real field aging at various time spans has been detected by EL imaging, maximum power measurement and dark I-V analysis. The obtained degradation values of PV modules are 1.78, 7.06, 13.92, 17.04 and 17.42 % due to ageing at a period of 8 months, 16 months, 4 years, 9 years and 11 years, respectively. The reason behind this degradation is attributed to the reduction of shunt resistance which declines gradually as result of aging. The degradation rate of a PV module has been estimated as 18.61 % after 21 years of aging. Temperature coefficient of maximum power of PV module also degrades due to aging. And the rate of temperature coefficient of maximum power degradation decreases with the increase of aging period.

11 illus, 8 tables, 38 ref

025046   MOUSAVI M, SHOJAEI M R (Physics Dep, Shahrood Univ of Technology, Shahrood, Iran, Email: nuclear.physics2020@gmail.com) : Relativistic solution of Eckart plus Hulthen potentials in the presence of spin and pseudospin symmetry. Indian J Pure Appl Phys 2018, 56(3), 218-25.

In this paper Dirac equation has been solved approximately for Eckart plus Hulthen potentials with spin symmetry and pseudospin symmetry for k≠0. The formula method has been used to obtain the energy Eigen-values and wave functions. The energy Eigen-values and wave functions have also been discussed for the special case of modified Eckart plus Hulthen potentials for the spin and pseudospin symmetry with formula method. To show the accuracy of the present model, some numerical values of the energy levels have been shown.

4 illus, 46 ref

025045   BHATT S, KUMAR M (Physics Dep, G B Pant Univ of Agriculture and Technology, Pantnagar- 263 145, Email: sandhyabhatt91@gmail.com) : Application of bond energy model for different nanomaterials. Indian J Pure Appl Phys 2018, 56(3), 210-7.

A simple theory has been developed using bond energy model of nanomaterials. The formulation has been obtained for the size and shape dependence of specific heat and conductivity. We have computed the size dependence of specific heat of Ag and Au nanoparticles. The results obtained have been compared with the available experimental data as well as with the earlier theoretical relation. It has been found that specific heat increases by decreasing the particle size. There is an appreciable improvement in the results as compared with the earlier relation and a good agreement with the available simulation data. We extend the model to study the effect of shape for the size dependence of specific heat and thermal conductivity of different nanomaterials. The results obtained have been discussed in the light of earlier investigations as well as experimental data. A good agreement between theory and experiment demonstrates the suitability of the formulation has been developed in the present paper.

7 illus, 2 tables, 37 ref

025044   FARAG A A M, TERRA F S, ASHERY A, FAHIM G M M, MANSOUR A M (Physics Dep, Jouf Univ, Jouf, Saudi Arabia, Email: alaafaragg@gmail.com) : Temperature dependence of J-V and C-V characteristics of n-InAs/p-GaAs heterojunctions prepared by flash evaporation technique and liquid phase epitaxy. Indian J Pure Appl Phys 2018, 56(3), 203-9.

In this work, n-type of InAs films have been successfully fabricated on p-GaAs monocrystalline substrates by both flash evaporation technique and liquid phase epitaxy. The elemental composition of the prepared films has been confirmed by energy dispersive X-ray (EDX) spectroscopy. The morphology of the films has been characterized by scanning electron microscopy (SEM). The current transport mechanisms of n-InAs/p-GaAs heterojunctions in the temperature range 300-400 K have been investigated. Temperature-dependent dark current density-voltage (J–V) studies under forward and reverse bias have been carried out for this purpose. In the temperature range studied, the dark current contribution in the low bias range is believed to be due to the generation-recombination of minority carriers in the space-charge region. A change in the preparation technique does not seem to have altered the dark current conduction mechanism. Capacitance-voltage (C–V) at various temperatures has been measured to identify the junction type as well as determination of the important junction parameters.

15 illus, 3 tables, 21 ref