Journal of Nepal Physical Society https://www.nepjol.info/index.php/JNPhysSoc <p>Official journal of the Nepal Physical Society.</p> Nepal Physical Society en-US Journal of Nepal Physical Society 2392-473X <p>All right reserved. No part of this Journal may be reproduced in any form or by any electronic or mechanical means, including information storage and retrieval system, without permission in writing from the publisher, except by a reviewer who may quote brief passage in a review. The views and interpretation in this journal are those of author(s) and they are not attributable to the NPS.</p> Diffusion coefficient and solvation free energy of sucrose in water: a molecular dynamics study https://www.nepjol.info/index.php/JNPhysSoc/article/view/42924 <p>In this work, we have carried out Molecular Dynamics Simulation technique to study the diffusion coefficients, radial distribution functions and solvation free energy of sucrose (C12H22O11) at different temperatures ranging from 298.15 K to 318.15 K. We have taken 2 molecules of sucrose in 1343 molecules of extended simple point charge (SPC/E) water model. The self-diffusion coefficients are obtained by applying linear best fit to the mean squaredisplacement (MSD) plot and binary diffusion coefficients are obtained by using Darken’s relation. Arrhenius equation has been used to show a linear relationship between natural logarithm of binary diffusion coefficient and reciprocal of temperature. The structural analysis of the solution has been carried out with the help of radial distribution functions (RDFs) of its constituents. The solvation free energy of sucrose is studied at 300 K by using free energy perturbation method like Bennett Acceptance Ratio (BAR). The results of binary diffusion coefficients obtained from this simulation work agree very well with the previously reported experimental data.</p> D. Sapkota N.P. Adhikari Copyright (c) 2021 Journal of Nepal Physical Society 2021-12-31 2021-12-31 7 4 1 9 10.3126/jnphyssoc.v7i4.42924 Estimation of Time Evolution of Muon Spin Polarization in 14N and 15N Systems https://www.nepjol.info/index.php/JNPhysSoc/article/view/42925 <p>In muon spin rotation and relaxation (SR) method, time evolution of muon spin polarization provides the information about local electronic and spin dynamic states of the material. Quantum simulation and estimated frequency of calculated the spectra help to interpret the observed polarization spectra. Based on spin dipole interaction between the muon and nearby nuclei (<sup>14</sup>N, <sup>15</sup>N and proton) in zero field measurement case, muon spin polarization spectra and corresponding frequencies are estimated using the quantum simulation. The oscillation frequency increases with approaching the muon towards the nuclei. Variation of separation between frequency positions with changing distance between muon and nuclei indicates the distribution of the magnetic field at the muon site. This study will help to distinguish the origin of oscillation in zero field μSR spectra in the isolated system containing <sup>14</sup>N and <sup>15</sup>N nuclei (e.g., glycine with <sup>14</sup>N, glycine with <sup>15</sup>N).</p> A.D. Pant Copyright (c) 2021 Journal of Nepal Physical Society 2021-12-31 2021-12-31 7 4 10 13 10.3126/jnphyssoc.v7i4.42925 Soft Chemical Synthesis of Nickel-Zinc-Cobalt-Ferrite Nanoparticles and their Structural, Morphological and Magnetic Study at Room Temperature https://www.nepjol.info/index.php/JNPhysSoc/article/view/42926 <p>The cobalt substituted Nickel-Zinc ferrites with the composition Ni<sub>0.95-x</sub>Zn<sub>0.05</sub>Co<sub>x</sub>Fe<sub>2</sub>O<sub>4</sub>, for x= 0.01, 0.02, 0.03, 0.04, 0.05 and 0.06 were synthesized by the soft chemical route method and were found to have cubic system of ferrimagnetic spinel using XRD. The grain sizes decreases significantly with the cobalt content (x) and are 1.62-1.36nm for x = 0.01 to 0.06 which are small enough to produce appropriate high density recording media. The particle size is found to be in the range 29-22 nm with the help of SEM. Their magnetic properties determined with VSM show the dependency on the exchange interaction due to the cobalt substitution between the metal ions of tetra and octahe.</p> D. Parajuli V.K. Vagolu K. Chandramoli N. Murali K. Samatha Copyright (c) 2021 Journal of Nepal Physical Society 2021-12-31 2021-12-31 7 4 14 18 10.3126/jnphyssoc.v7i4.42926 First Principles Study of Structural, Electronic and Magnetic Properties of Defected (Monovacant) Hexagonal Boron Nitride Sheet https://www.nepjol.info/index.php/JNPhysSoc/article/view/42927 <p>The structural, electronic, and magnetic properties of vacancy structures with triangular shape are related to the defect in single hexagonal boron nitride (h-BN) sheet. It is investigated by using density functional theory calculations. The first-principles calculations based GGA functionals have been implemented to study the structural, electronic and magnetic properties of pure and defected hexagonal boron nitride (h-BN) monolayer sheet using Quantum ESPRESSO (QE) package, 6.5 version. The calculated values of formation energy reveal the structural stability of the defected systems. The formation energies for B and N vacant system are found to be 16.45 eV and 12.87 eV respectively. This predicts that the N vacant system is more preferable with lower formation energy. The defect in h-BN seems to be changing its band gap and magnetic properties of h-BN system. The 6.25 % B-vacancy results h-BN to be half metallic ferromagnetic with total magnetization of 2.74µB/cell. Further, 6.25 % N-vacancy causes it to be magnetic semiconductor with total magnetization 1.00µB /cell.</p> R. Karki K. Khatri K. Adhikari N.P. Adhikari N. Pantha Copyright (c) 2022 Journal of Nepal Physical Society 2021-12-31 2021-12-31 7 4 19 27 10.3126/jnphyssoc.v7i4.42927 A Detailed Morphological and Spectroscopic Study of Merging Dwarf Galaxy PGC 030133 https://www.nepjol.info/index.php/JNPhysSoc/article/view/42928 <p>We present a detailed morphology and spectroscopic study of a merging dwarf galaxy PGC 030133. Using the publicly available fiber spectroscopic data from the Sloan Digital Sky Survey (SDSS), we analyzed nine-strong emission lines of wavelength range 4336 Å to 6739 Å. We find that the strongest emission line is OIII5007, with an intensity of 146.32 × 10<sup>-17</sup> erg/s/cm<sup>2</sup> /Å. The observed emission lines are well fitted with a Gaussian profile with a coefficient of regression greater than 96%, and the derived full-width half maximum (FWHM) is less than 4.2Å. The Balmer decrement, characterized by the line ratio between H<sub>α</sub> and H<sub>β</sub> is 3.07, suggesting a presence of dust at the center of PGC 030133. We derived the star-formation rate and emission line metallicity of PGC 030133 using extinction corrected emission line fluxes. SFR derived from Hα emission line flux is 0.0033 M<sub>ʘ</sub>year<sup>-1</sup> and emission line metallicity derived from flux ratio between NII and H<sub>α</sub> is 8.13 dex. Using the SDSS, g, and z-band imaging data, we derived morphological parameters. PGC 030133 has a half-light radius of 3.38 arc second and 3.05 arc second in g-band and z-band respectively and observed one-dimensional light profile is well fitted with a Sersic function with near exponential Sersic index ~ 0.9.</p> D.N. Chhatkuli S. Paudel B. Aryal Copyright (c) 2021 Journal of Nepal Physical Society 2021-12-31 2021-12-31 7 4 28 35 10.3126/jnphyssoc.v7i4.42928 Examination of Security Features in Nepali Currency of Denomination Rs. 500 and Rs. 1000 Using Video Spectral Comparator-6000 https://www.nepjol.info/index.php/JNPhysSoc/article/view/42929 <p>In this work, we have studied security features of Nepali currencies of denomination Rs. 500 and Rs. 1000 of recent two series with the help of Video Spectral Comparator-6000. During examination, mostly ultraviolet, normal, transmitted and oblique light are used. We found nine different security features like fluorescence, water mark, micro text, security thread, intaglio print, see through registor, emboss, optically variable ink and latent image in this work. One feature, latent image is found to be completely removed in new series of both Rs. 500 and Rs. 1000 whereas new important security feature optically variable ink is introduced in new series of Rs. 500. Besides these two features, some are unchanged while some are modified.</p> R. Giri P. Bhattarai S. P. Chimouriya B. R. Ghimire Copyright (c) 2021 Journal of Nepal Physical Society 2021-12-31 2021-12-31 7 4 36 42 10.3126/jnphyssoc.v7i4.42929 Study of Alpha Particle Impact Double Ionization Cross Sections of Cu Atom https://www.nepjol.info/index.php/JNPhysSoc/article/view/42930 <p>Semi-classical binary encounter approximation has been used for the study of ionization cross sections of Cu atom at ground state. Projectile, alpha particle, with energy varying from threshold to 360 keV/amu are considered for direct double ionizations cross section. Out of the two path ways of ionization we have ruled out the indirect process (like excitation-auto ionization, Auger effect) of double ionization. We considered direct - ionization of outer shells of Cu atom. Vriens accurate expression of cross section for energy transfer Δ<em>E(</em>σ<sub>Δ<em>E </em></sub>) and Hertree-Fock velosity distribution function for the target electrons are used. The theoretical value of double ionization cross sections at impact energy 300 keV/amu is 0.98 x 10<sup>-16</sup> cm<sup>2</sup> which is same as experimental values at that impact energy. Above energy of 300 keV/amu, the calculated results underestimates the experimental data and at 360 keV/amu their magnitude are 0.77 x 10<sup>-16</sup> and 1.0 x 10<sup>-16</sup> respectively. Above impact energy of 75keV/amu, all the theoretical results have ratio factor within 2. Out of the total number of theoretical data 75% are under valid range of ratio factor 2 and among the valid range 41% have ratio factor below 1.325 and hence calculated results of double ionization cross section lie in the acceptable range. The linear correlation coefficient (R square) and standard deviation (SD) of linear fit are 0.6984 and 0.7883 respectively. In low energy range the theoretical results are more apart from corresponding experimental values and possess relatively more error compared to intermediate and higher energy region. Calculated results are in satisfactory agreement with experiment in intermediate and high energy range.</p> S. P. Gupta K. Yadav R. Ghimire R. Khanal L. K. Jha Copyright (c) 2021 Journal of Nepal Physical Society 2021-12-31 2021-12-31 7 4 43 51 10.3126/jnphyssoc.v7i4.42930 Computational Study on Vibrational Properties of Thyroxine Molecule in Different Charge States https://www.nepjol.info/index.php/JNPhysSoc/article/view/42931 <p>The vibrational frequencies of thyroxine (T4) molecule are calculated through computational method and major modes of vibration are assigned to corresponding frequencies in this research work. First we took neutral isolated T4 molecule for our study, and then we extend our work to anion state. The shift produced in the frequency and IR intensities for different vibrational modes has been calculated for change in state from neutral to anion. In addition, the difference spectra for these two charge states has also been studied for the T4 molecule by adding the dimethyl sulfoxide (DMSO) solvent. Furthermore, the same calculations are performed for the isolated neutral T4 molecule with C<sup>13</sup> labelling. All these calculations are carried out by density functional calculations with the B3LYP hybrid functional applying the SDD effective core potential basis set. The calculated geometrical parameters are in good agreement with the experimental results. Additionally, the calculated frequencies lies within the characteristic region belonging to the respective mode of vibrations.</p> S. Dhital K. Pudasainee H. P. Lamichhane Copyright (c) 2021 Journal of Nepal Physical Society 2021-12-31 2021-12-31 7 4 52 58 10.3126/jnphyssoc.v7i4.42931 Measurements of electron energy distribution on electron cyclotron resonance plasma operated with hydrogen gas https://www.nepjol.info/index.php/JNPhysSoc/article/view/42932 <p>This article deals with the production of electron cyclotron resonance hydrogen plasma in a closed gas chamber called Menja device. For this purpose, 2.45 GHz frequency and various power i.e. 0 - 500 W are employed. The flow of hydrogen gas is controlled manually with the range 1.5 – 10 sccm maintaining pressure range 10<sup>-5</sup> – 10<sup>-4</sup> mbar. The Langmuir probe technique is used to drag the electrons and ions by biasing the probe positively and negatively to study the key parameters such as ion saturation current, floating potential, plasma potential, electron temperature and plasma density. Besides these, to obtain information on electron energies and their interaction with plasma, the electron energy distribution function (EEDF) has been studied with the help of 2<sup>nd</sup> derivative of current obtained from the differentiator. For this purpose, an analogue differentiation circuit was built and tested.</p> L.N. Mishra Å. Fredriksen Copyright (c) 2021 Journal of Nepal Physical Society 2021-12-31 2021-12-31 7 4 59 63 10.3126/jnphyssoc.v7i4.42932 Dust Properties of Super-Nova Remnant (Crab Nebula) Using AKARI Survey https://www.nepjol.info/index.php/JNPhysSoc/article/view/42933 <p>We present the distribution of dust color temperature, Planck's function, dust mass, and visual extinction in the far-infrared (140 μm and 90 μm) AKARI surveys of the Crab Nebula using Sky View Virtual Observatory. With a systematic search of a supernova remnants, we found Crab Nebula at R. A. (J2000) / Decl. (J2000) = 05<sup>h</sup> 34' 31.94"/+22° 00' 52.20". The maximum flux is found to be 145.94 MJysr<sup>-1</sup> at 140 μm and 177.01 MJysr<sup>-1</sup> at 90 μm wavelength. The total dust mass of the Supernova remnant is estimated to be 6.11×10<sup>39</sup> kg (3.07×10<sup>9</sup> M<sub>ʘ</sub>) and the dust color temperature is found in the range between 31.16 K to 47.11 K with mean value of temperature of 38.07 K. Similarly we obtained the value of Planck’s function in the range of 3.96 × 10<sup>-15</sup> Wm<sup>-2</sup>sr<sup>-1</sup>Hz<sup>-1</sup> to 1.96 × 10<sup>-14</sup> Wm<sup>-2</sup>sr<sup>-1</sup>Hz<sup>-1</sup> with average value 9.59 × 10<sup>-15</sup> Wm<sup>-2</sup>sr<sup>-1</sup>Hz<sup>-1</sup>. The value of visual extinction ranges from 9.21 × 10<sup>-14</sup> mag to 2.70 × 10<sup>-13</sup> mag with mean value of 1.57 × 10<sup>-13</sup> mag. The distribution trend of flux, dust color temperature, and Planck’s function are nearly similar, whereas dust mass and visual extinction follow an inverse relationship with the previous three parameters.</p> A.K. Jha A. Yadav D.R. Upadhyay B. Aryal Copyright (c) 2021 Journal of Nepal Physical Society 2021-12-31 2021-12-31 7 4 64 70 10.3126/jnphyssoc.v7i4.42933 Trend Analysis of Rainfall, Temperature and Relative Humidity over Kathmandu, Nepal https://www.nepjol.info/index.php/JNPhysSoc/article/view/42934 <p>Five years (2012-2016) data of Rainfall, Relative Humidity and Temperature from Tribhuvan International Airport Kathmandu, Nepal (TIA) station were analyzed. Nepal lies in the subtropical region in which experience four seasons in a year i.e., winter, spring, summer and autumn. The Mean, Correlation(r), And P-value were calculated to study the correlation between Rainfall, Relative Humidity and Temperature. Assuming the type I error alpha (α) as 5% the p-value was compared to it. T test was used to calculate the p-value. Assuming null Hypothesis (H<sub>0</sub>) to show insignificant relation between two variable and alternative hypotheses (H<sub>1</sub>) to show significant relation between two variables. The monthly analysis also shows the period of Highest Rainfall, Temperature and Relative Humidity Between June or July or August for the location of TIA Kathmandu, Nepal. The relation between Rainfall vs Relative Humidity and Relative Humidity vs temperature was found to be insignificant respectively throughout all five years. The relation between Rainfall and Temperature was found to be significant throughout all five years.</p> A. Regmi H.K. Sah B. Adhikari D. Pandit Copyright (c) 2021 Journal of Nepal Physical Society 2021-12-31 2021-12-31 7 4 71 79 10.3126/jnphyssoc.v7i4.42934 Editorial Vol.7(4) https://www.nepjol.info/index.php/JNPhysSoc/article/view/42935 <p>No abstract available.</p> Binod Adhikari Copyright (c) 2022 Journal of Nepal Physical Society 2021-12-31 2021-12-31 7 4 10.3126/jnphyssoc.v7i4.42935