JULY 18, 2020


SESSION - III: Astrophysics

Abstract Number ANPA2020_0009
Author/s Angel Bashyal (1) , Aayush Gautam (2) Suman Satyal (3) Shree Krishna Bhattarai (4)
Title Orbital dynamics of hypothetical exomoons around a Jupiter-type exoplanet, Laligurans.
Affiliation/s GoldenGate Int'l College, (TU) (1) , Birendra Multiple Campus(TU) (2) University of Texas at Arlington (3) University of North Carolina at Charlotte(4)
Abstract " A satellite is stable when it lies between the host planet’s Hill sphere and Roche limit. Hill sphere approximates the farthest gravitational influence a planet can have on its moons. If an object is gravitationally perturbed and pushed outside of this sphere, it will escape the orbit. Roche limit is the minimum distance from a center of a planet that a satellite can maintain stable orbits. Below this limit, the orbit decays and the satellite spirals into the host planet. In this work, we have determined orbital parameters that yield stable orbits for two hypothetical exomoons around a Jupiter-type exoplanet called Laliguras (HD-100777b) around the host star, Sagarmatha (HD-100777). We considered the mass of the exomoons to be equal to mass of Earth and mass of Moon. For each set of the exomoon’s parameters, we plotted the Mean Exponential Growth for Nearby Orbits (MEGNO) maps to determine the range of exomoon’s periodic, aperiodic and quasi-periodic regions. Then, by selecting few points in these phase space maps, a direct orbital simulation is performed (for up to 50 Myr) to generate time series plots of the exomoons’ semimajor axis, eccentricity and other Keplerian elements. These time series plots are further analyzed to study the dynamics of the exomoons in 2-D and 3-D planes. "

Abstract Number ANPA2020_0003
Author/s Agrima Nana Shrestha (1) , Yenca Migoya Orue (2)
Title Comparative study of GPS-TEC and IRI- 2016 TEC during Total Solar Eclipse of 22 July 2009 over Nepal
Affiliation/s Ascol Campus (1) , ICTP (2)
Abstract " The present paper inspects the ionospheric response in terms of Total Electron Content (TEC) during the Total Solar Eclipse of 22 July 2009. The ionospheric behaviour was investigated through the changes in TEC by using the data archived at BRN2, RMTE, DNGD, NPGJ, and TPLJ Global Positioning System (GPS) stations. Our study is based on GPS-TEC measurements from a widely distributed GPS network over different geographical location of Nepal by taking July 17-21 as pre-event, July 22 as a main-event and July 23-27 as a post-event and its comparison with International Reference Ionosphere (IRI-2016) model to reveal the potential of IRI model in special events like solar eclipse with storm effect. The total solar eclipse of July 22, 2009, was totally visible from BRN2 and RMTE stations and partially visible from DNGD, NPGJ, and TPLJ stations. The result reveals that the amount of reduction in TEC is proportional to the magnitude of the total solar eclipse. The latitude also depends on the magnitude of the solar eclipse but the longitude doesn’t depend on it. The latitude is obtained to be directly proportional to the effect of the solar eclipse while longitude shows the inverse effect. TEC depletion up to 5% from pre-event to main-event and enhancement up to 30% from main-event to post-event were observed during the totality of the eclipse.The eclipse was followed by the geomagnetic storm all over Nepal which lasted for 10 hours which was the reason for the enhancement of TEC up to 50% in the main-event day from pre-event and post-event. It was also found that the IRI-2016 model underestimates the GPS-TEC and doesn’t seem to be effective for a particular event. "

Abstract Number ANPA2020_0005
Author/s Alisha Paudel (1) , Aabiskar Bhusal (2)
Title Electronic Structure Calculation Of Some Interstellar Molecules
Affiliation/s Prithivi Narayan campus, Tribhuwan university , Pokhara (1) , Physics Research Initiatives, Pokhara , Nepal (2)
Abstract " Abstract hidden under author's request. "

Abstract Number ANPA2020_0014
Author/s Ashok Silwal (1) , Narayan Prasad Chapagain (2) and Sujan Prasad Gautam (3)
Title GPS Observations of Ionospheric TEC Variations During the 26th December 2019 Solar Eclipse
Affiliation/s Patan Multiple Campus (1) , Department of Physics, Amrit Campus, Tribhuvan University, Kathmandu, Nepal (2) and Central Department of Physics, Tribhuvan University, Kirtipur, Nepal (3)
Abstract " Abstract hidden upon Author's request "

Abstract Number ANPA2020_0016
Author/s Babu Ram Sharma (1) , Narayan P. Chapagain (2) Bhuwan Joshi, (3)
Affiliation/s Prithvi Narayan Campus, Tribhuwan University,Nepal (1) , Dept. of Physics, Amrit Campus, Tribhuwan University, Nepal (2) Udaipur Solar Observatory, Physical Research Laboratory, Udaipur 313 001, India (3)
Abstract " Abstract hidden under author's request. "

Abstract Number ANPA2020_0017
Author/s Basu Dev (1) , Narayan P. Chapagain (2), Karan Bhatta (3), Aditya Singh Thapa (4)
Title Ionospheric Perturbations Due to MEXICO Earthquakes as Measured from GPS-TEC Data
Affiliation/s Institute of Science and Technology, IOST, Tribhuvan University (1) , Amrit Campus ,Tribhuvan University(2); National Science and Technology,NAST (3); St.Xavier’s college Maitighar ;Nepalese Center for Research in Physical Sciences (NCRPS) (4)
Abstract " Abstract not displayed upon author's request "

Abstract Number ANPA2020_0019
Author/s Bhogendra Kathayat (1) , N.P.Chapagain (2), A.K. Panday (3) Y.R. Lamsal (4)
Title Long-term atmospheric visibility variation in two cities of West Nepal (1977-2020): A proxy for local and regional atmospheric aerosol loads
Affiliation/s Tribhuvan University,Central Department of Physics, Kirtipur, Kathmandu, Nepal (1) , Department of Physics, Amrit Science Campus, Tribhuvan University, Kathmandu, Nepal (2) Ullens school, Satdobato, Lalitpur, Nepal (3) Department of Management Informatics and communication, Kathmandu University, Dhulikhel, Nepal (4)
Abstract " The atmospheric visibility is a proven indicator of ambient air quality by proxy. The trend of visibility is less understood in our region. In this study, two cities of Nepal; Bhairahawa (27.506ºN, 83.416ºE) and Surkhet (28.6ºN, 81.617ºE) were selected. Historical climatological data from 1977 to 2020 were collected. Two well-established methods: ‘percentile analysis’ and ‘annual good/bad day percentage’ were used to investigate the trend of visibility. Degradation of visibility in Surkhet during the 1980s was reflected from percentile analysis and minor recovery during the 2000s was observed. Visibility in Bhairahawa began a notable decline trend since the mid-80s. The decline continued and suffered poor visibility situation in recent years (good day percentage ~ 0%, bad day percentage ~ 47%). In Surkhet, marked degradation of visibility started comparatively late since 2010 when simultaneous and sharp increase in bad day percentage (1-22.5% max) and decrease in good day (36.5-0%) percentage is observed. Strong seasonality in visibility was observed in both places. Bhairahawa displayed worse visibility conditions in winter (4.7 km), as expected. In contrast, Surkhet showed the lowest visibility (16.7 km) in late summer. These marked trends in visibility decline show invalid environmental policy despite continued emissions of pollutants. This study necessitates a macro-control of pollution emissions to effectively reduce air pollution deterioration. "

JULY 18, 2020


SESSION - IV: Condensed Matter

Author/s Madhav Prasad Ghimire
Title Realization of Dirac Fermions and Flat bands in Kagome Metal FeSn
Affiliation/s Tribhuvan University, Nepal
Abstract " Recently a newly synthesized material iron and tin atoms in one-to-one ratio, i.e., FeSn, was found to display a unique behavior: Dirac fermions and Flat bands. This material simultaneously hosts light massless particles (called Dirac fermions) and infinitely heavy particles (which manifest experimentally as flat bands in the electronic structure of the material)." This study combines various field of physics such as topology, magnetism, and strongly correlated electrons in a single platform of ideal kagome metals. The combination of 2D and 3D electronic behaviors in a single material ‘FeSn’ could be harnessed to engineer fast-switching/low-power spintronic devices, spin superconductors and a high-temperature quantum anomalous Hall effect. [1]
Ref: [1]. Kang, et al., Nat. Mater. 19, 163–169 (2020) "

Abstract Number ANPA2020_0090
Author/s Tej B. Limbu (1), Basant Chitara (2), Jason D. Orlando(2), Martha Y. Garcia Cervantes(2), Shalini Kumari(3), Qi Li,(3) Yongan Tang,(3) Fei Yan (4)
Title Surface-engineered Ti3C2Tx MXene with Enhanced Conductivity, Oxidation Stability, and Surface-enhanced Raman Scattering Activity
Affiliation/s North Carolina Central University, NC (1) , Department of Chemistry and Biochemistry, North Carolina Central University, Durham, NC 27707, USA (2) Department of Mathematics and Physics, North Carolina Central University, Durham, NC 27707, USA (3) Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA (4)
Abstract " Transition metal carbides (MXenes) are an emerging family of highly conductive two-dimensional materials with additional functional properties introduced by surface terminations. Further modification of the surface terminations makes MXenes even more appealing for practical applications. Herein, we report a facile and environmentally benign synthesis of surface-engineered Ti3C2Tx MXene (r-Ti3C2Tx) via a simple treatment with L-ascorbic acid at room temperature with enhanced quality. r-Ti3C2Tx shows a six-fold increase in the electrical conductivity, from \ 471 \pm49 for regular Ti3C2Tx to 2819\pm306 S/m for the reduced version. Additionally, we show an enhanced oxidation stability of r-Ti3C2Tx as compared to regular Ti3C2Tx. An examination of the surface-enhanced Raman scattering (SERS) activity reveals that the SERS enhancement factor of r-Ti3C2Tx is an order of magnitude higher than that of regular Ti3C2Tx. The improved SERS activity of r-Ti3C2Tx is attributed to the charge transfer interaction between the MXene surface and probe molecules, re-enforced by increased electronic density of states (DOS) at the Fermi level of r-Ti3C2Tx. The findings of this study suggest that reduced MXene could be a superior choice over regular MXene, especially for the applications that employ high electronic conductivity, such as electrode materials for batteries and supercapacitors, photodetectors, and SERS-based sensors. "

Abstract Number ANPA2020_0004
Author/s Alisha Budhathoki (1) , Madhav Prasad Ghimire (1,2,3)
Title First Principles Investigation on the Electronic and Magnetic Properties of Kagome System: ScFe6Ge4
Affiliation/s Central Department of Physics, Tribhuvan University, Kirtipur, 44613, Kathmandu, Nepal. (1) Leibniz Institute for Solid State and Material Research (FIW), Dresden, Dresden 01062, Germany. (2) CMPRC Butwal, Butwal-11, Rupandehi, Nepal (3)
Abstract " Abstract hidden upon Author's request."

Abstract Number ANPA2020_0006
Author/s Alok Lal Karn (1) , Suman Acharya (2) and Gopi Chandra Kafle (2)
Title Electronic and Magnetic related properties Of MXene and corresponding MAXphase
Affiliation/s Tribhuvan University (1) , Tribhuvan University (2)
Abstract " In the field of the 2D material MXenes are the one of candidate for development of technologies and sustainable development of society. MXenes are the transition metal carbide and /or Nitride. Here we use to study about the MXene(Ti3C2) and their corresponding MAX-phase(Ti3AlC2) by DFT Method. Bare MXene(Ti3C2) are metallic as their parent MAX -phase(Ti3AlC2) but shows magnetic nature with certain magnetic moment. Surface termination like Ti3C2-Tx (-Tx are -OH , -F, or -O) helps to preserve Metallic nature but destroy Magnetic nature. Higher value of DOS at the fermi level indicate higher electrical conductivity which can be use for the several energy storage devices, spintronic devices and many more. "

Abstract Number ANPA2020_0061
Author/s Prena Chaudhary (1) , Gopi Chandra Kaphle (1)
Affiliation/s Central Department of Physics, Tribhuvan University (1)
Abstract " A Large number of Heusler alloys have attracted considerable attention in the emerging field of spintronics due to its high spin polarization at the fermi level. In this work, we studied electronic and magnetic properties of full Heusler alloy Co2FeAl using the Plane wave pseudopotential method within the DFT framework implemented by Quantum ESPRESSO code. The band structure and DoS calculation shows the existence of an energy gap by 0.13 eV in its minority spin channel and hence half metallic character. The calculated total magnetic moment is 5 μB/cell which is found to obey Slater-Pauling rule: Mt = Zt−24 for full Heusler alloys. We, in this study are going to describe the doping effect of Vanadium on electronic and magnetic properties of this compound at different concentrations. We will use empirical rule for atomic site occupation established for Heusler alloys and calculate formation energy in order to find the occupation site of Vanadium. The strain effect on band structure will also be presented. "

Abstract Number ANPA2020_0012
Author/s Anjila Ghimire (1) , Dr Rishi Ram Ghimire (2), Anjilla Ghimire(1)
Affiliation/s Tribhuwan university (1) , University of Culcutta (2)
Abstract " Three terminal ammonia gas sensor is fabricated by the process of electrolytic method with the help of metal oxide as ZnO. Thin film of ZnO was formed by the method of spin coating/spray pyrolysis which is characterized by the XRD . The data obtained from current and volatge relation are analyzed and charecterized. The sensitivity of the system is also determined. Apart from this, the efficiency of the gas sensor is also optimized. "

Abstract Number ANPA2020_0020
Author/s Bibek S Dhami (1) , Ravi P.N. Tripathi (2), Kannatassen Appavoo (2)
Title Carrier dynamics in Perovskite microstructures
Affiliation/s University of Alabama at Birmingham (1) , University of Alabama at Birmingham (2)
Abstract " Hybrid perovskites nanomaterials have recently gained significant attention for advanced optoelectronic and energy harvesting applications. Nevertheless, comprehensive understanding several factors (engineering light-matter interaction, structurally correlated carrier dynamics, tailoring optical response etc.) are regarded as important parameters in its extensive utility. Herein, we would like to address some of these aspects using ultrafast pump probe microscopy and spectroscopy technique. Our findings underline the inherent correlation among structural morphologies, associated carrier lifetime and photoinduced emission phenomena. We envisage that our findings would be highly relevant in tailoring optical and electrical response in next generation quantum photonics devices and applications. "

Abstract Number ANPA2020_0053
Author/s Nikesh Maharjan (1) , Neelam Khan (2), Eli Janzen (3), J.H. Edgar (4), and Mim Nakarmi (2)
Title Luminescence properties and Chemical composition Analysis of Residual Impurities in Hexagonal boron nitride
Affiliation/s Brooklyn College and The Graduate Center of CUNY (1) , Department of Physics, Brooklyn College and the Graduate Center of the City University of New York, Brooklyn, NY 11210 (2), George Gwinnett College, School of Science and Technology, Lawrenceville, GA 30043 (3) Tim Taylor Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506 (4)
Abstract " Abstract hidden under author's request "


SESSION - V: Astrophysics

Abstract Number ANPA2020_0046
Author/s Manish Khanal (1), Devendra Raj Upadhyay (1)
Affiliation/s Amrit Science Campus (1)
Abstract " Abstract hidden upon author's request "

Abstract Number ANPA2020_0048
Author/s Megh Nath Upadhyay (1) , Ganga Prasad Adhikari (1), Sushma Khanal (1)
Title “ Formulating a Methodology to Calculate Local Sunrise-Sunset Times in Nepal ”
Affiliation/s T.U. (1)
Abstract " Abstract hidden under Author's request"

Abstract Number ANPA2020_0031
Author/s Drabindra Pandit (1) , Narayan. P. Chapagain (2); Binod Adhikari (3)
Title Analysis on the North-South Component of Geomagnetic Field with the Interplanetary Magnetic Field during Intense Geomagnetic Storms of 22 June 2015 and 25 August 2018
Affiliation/s Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, Nepal (1) , AmritCampus, Tribhuvan University, Thamel, Kathmandu, Nepal (2), St. Xavier’s College, Tribhuvan University, Maitighar, Kathmandu, Nepal (3)
Abstract " Abstract hidden upon Author's request "

Abstract Number ANPA2020_0034
Author/s Ganga Prasad Adhikari (1) , Prof. Dr. Narayan Prasad Chapagain (1), Dr. Suman Satyal (2), Dr. Shree Krishna Bhattarai (3), Meghnath Upadhayay (1), Sushma Khanal (1)
Title Determination of Sunrise and Sunset times for Bhairahawa airport, Nepal.
Affiliation/s Tribhuwan University (1), University of Airlington at Texas (2), University of North Carolina at Charlotte(3)
Abstract " Absence of systematic way of calculation of sunrise and sunset times becoming the big concern for different sectors like airport. The purpose of this study is to determine the formula from which we can calculate the sunrise and sunset time for different latitude and longitude and thus for Bhairahawa airport. By the determining the Sun’s position in the sky and by considering the orbital eccentricity and Earth’s obliquity, we can calculate the equation of time. Using equation of time and different values of latitude and longitude we can have analemma for our required time. The study of analemma can provide the information about the motion of Sun. This study definitively provide the required formula for the determination of sunrise and sunset time. Keywords: Latitude, Longitude, Analemma, Declination, Orbital eccentricity. "

Abstract Number ANPA2020_0039
Author/s Janak Ratna Malla (1) , Janak Ratna Malla (2), Walter Saurer (3), Binil Aryal (2)
Title Spatial orientations of angular momentum vectors of galaxies in Supercluster S [173+014+0082]
Affiliation/s Amrit Campus,Thamel,T.U. (1) , Central department of Physics, kirtipur ,Kathmandu (2), Institute of Astro-particle Physics, Innsbruck university, Austria (3)
Abstract " We present a study of spin vector orientation of 1331 SDSS (Sloan Digital Sky Survey) galaxies in Supercluster S [173+014+0082] having redshift 0.02 to 0.03. The database of these galaxies are taken from SDSS (Sloan Digital Sky Survey) 7th and 9th data release. We have converted two dimensional data to three dimensional by Godlowskian Transformation using position angle-inclination angle method. Three standard statistical tools namely Chi-square test, auto-correlation test and Fourier test are carried out in order to determine the non-random effects in the expected isotropic distributions. We intend to find non-random effects in the spatial orientation of galaxies in the Supercluster. No preferred alignment of angular momentum vectors is noticed, supporting Hierarchy model of galaxy formation. "

Abstract Number ANPA2020_0026
Author/s Dev Joshi (1), Keith Groves (2)
Title The dependence of the Irregularity parameter characterizing the Equatorial Ionospheric Irregularities on the background ionospheric density
Affiliation/s The University of Scranton (1) , Institute for Scientific Research (ISR), Boston College (2)
Abstract " The low-latitude ionosphere is characterized by large-scale instabilities in the post-sunset hours due to the distinct geometry of the earth’s magnetic field lines at the equator. The magnetic field lines are horizontal at the equator contributing to the high vertical drift velocity of the plasma bubbles growing from the bottomside of the ionospheric F-region. The phenomenon, commonly known as equatorial spread F, is an important problem in aeronomy as it can cause radio wave scintillation effects representing the most critical impacts of space weather on man-made technologies, such as satellite communications and global navigation satellite systems (GNSS). Here, we seek to characterize the spatial distribution of equatorial ionospheric irregularities and try to understand the dependence of the peak heights of the irregularities at the magnetic equator, also called as apex-altitude, on solar flux by analyzing in-situ observations made on-board the Communications/Navigations Outage Forecasting System (C/NOFS) satellite mission. Since the irregularities map along the magnetic field lines, their height above the magnetic equator determines the spatial extent of the irregularities in latitude allowing us to identify regions affected by space weather impacts. In this investigation, we seek to understand the possible dependence of the irregularity parameter characterizing the equatorial ionospheric irregularities on the background ionospheric density. This is a critical examination of the irregularity parameter to confirm our results on the peak-height distributions of the irregularities at the magnetic equator and also several other studies which have employed similar definition of the irregularity parameter. "

Abstract Number ANPA2020_0027
Author/s Dev R Sadaula (1), Manuel Bautista (1), Dr. Timothy Kallman (2)
Title Time Dependent Photo-Ionization of Warm Absorbers Found in Active Galactic Nuclei.
Affiliation/s Physics Department, Western Michigan University, Kalamazoo MI (1), Laboratory of High Energy Astrophysics, NASA Goddard Space Flight Center, Greenbelt, MD (2)
Abstract " Hot and ionized plasma coming out from the center of active galactic nuclei is termed as warm absorbers. Absorption lines and edges in UV and X-ray of AGN warm absorbers have been studied over long period of time. However, fundamental properties of warm absorbers like: What is the mechanism which drives the outflow? What is the gas density in the flow and the geometrical distribution of the outflow? Where does the outflow originate and what is its fate? Do ionized outflows play an important role on the host galaxy chemical history and evolution? are not determined precisely and are of great interest. Intrinsic UV and X-ray absorbers show large global covering factors of the central continuum source. Blue shifted absorption lines in the spectra reveal the presence of massive outflows of ionized gas from their nuclei at speed of ∼ 1000 Km/s. Which potentially can reach to ISM and can have impact on the chemical evolution and star formation process in the host galaxy. This could even reach to intergalactic medium and enrich it with heavier elements called the feedback mechanism. The resulting mass outflow rate can be a substantial fraction of the accretion rate required to power the AGN. Thus, WA can be dynamically important and the knowledge of their state, location, geometry and dynamics would help in understanding the central engines of AGN. Progress towards understanding warm absorbers is limited by the assumption used so far in photoionization modeling: that the gas is in ionization and excitation equilibrium. This is almost certainly not correct in detail; the dynamical timescales in the flow are comparable to or less than the timescales characterizing the ionization and excitation, and the inverse processes in the gas responsible for the lines we observe. Which means the gas departs from equilibrium and so temporal dependency for ionization, heating & cooling and radiative transfer equation has to be included in the modeling of the absorber. The ongoing research is about inclusion of time dependence in the photoionization code XSTAR, which has already been developed. The goal is to do this in a way which is as general and computationally efficient as possible. Then we will use this code for self-consistent calculations of warm absorber dynamics. "


SESSION - VI: Condensed Matter Physics

Abstract Number ANPA2020_0028
Author/s Dev Raj Joshi (1)
Title Electricity Generated by Sound Energy Based on the Soundelectric Effect
Affiliation/s Tribhuvan University (1)
Abstract " Abstract hidden upon Author's request "

Abstract Number ANPA2020_0025
Author/s Deependra Parajuli (1) , Kanta Jayadev (2), M. K. Raju1 (2), N. Murali (3), K. Samatha1 (4)
Title Structural, Morphological, Magnetic and DC resistivity studies of Cu substituted Ni-Zn ferrite
Affiliation/s Nepalese Society of Microscopy (1) , Department of Physics, Andhra University, Visakhapatnam (2) Department of Physics, WISTM Engineering College, Pinagadi, Visakhapatnam (3) Department of Physics, College of Engineering (A), Andhra University, Visakhapatnam, India (4)
Abstract " Cu substituted Ni0.5-xCuxZn0.5Fe2O4 (x = 0, 0.05, 0.1, 0.15 and 0.2) samples is synthesized using the sol-gel auto-combustion process. X-ray diffraction shows its cubic spinel structure. The lattice constant decreases as the Cu content increases. The size of the crystallites are in the range of 29.01–42.68 nm. The wave numbers of tetrahedral and octahedral sites sighted in the FTIR spectra are similar to that of the precursor. The increment on the copper content increases the DC conductivity. The electrical resistivity decrease with increase in the temperature i.e. it has negative temperature coefficient with resistance similar to semiconductors. The remnant ratios R obtained from VSM show their isotropic nature forming single domain ferrimagnetic particles. The resultant material is widely significant as indicated by its result. "

Abstract Number ANPA2020_0023
Author/s Chandra Mani Adhikari (1) , I. V. Bondarev (1)
Title Optical response of ultra-thin carbon nanotube films
Affiliation/s North Carolina Central University, Durham, NC (1)
Abstract " Finite-thickness films of aligned single-wall carbon nanotubes (SWCNT) are demonstrated to have a tunable negative dielectric response in a wide photon energy range. We explain this theoretically using the Maxwell-Garnett (MG) mixing for the dielectric responses of planar periodic arrays of identical SWCNTs. We start with the calculation of the conductivity of an individual SWCNT using the k.p method. Then we derive a semi-analytical expression for the dielectric tensor of an ultrathin finite-thickness periodically aligned SWCNT array. The dielectric responses of about a dozen of SWCNT arrays with different chiralities and very close diameters are then mixed using the MG method to obtain the dielectric response of the SWCNT film which explains the experimental ellipsometry measurements. We also note that the inhomogeneously broadened interband plasmon resonance overlaps with the broadened exciton resonance, making the exciton-plasmon coupling and associated photon bandgap formation possible in these systems. "

Abstract Number ANPA2020_0029
Author/s Dina Michel (1) , Nishchal Thapa Magar (1), Nicholas Bishop (1), Lekhanath Poudel (2), Jeffrey Lynn (3), John Mitchell (4), Nirmal Ghimire (1)
Title Tuning Topological Properties by Chemical Substitution in CoNb3S6
Affiliation/s Department of Physics and Astronomy, George Mason University (1), Department of Materials Science and Engineering, University of Maryland, College Park(2); NIST Center for Neutron Research, National Institute of Standards and Technology (3); Materials Science Division, Argonne National Lab (4);
Abstract " An ordinary Hall effect in a conductor arises due to the Lorentz force acting on the charge carriers. In ferromagnets, an additional contribution to the Hall effect, the anomalous Hall effect (AHE), appears proportional to the magnetization. It is also known that the AHE can arise in non-collinear and non-coplanar antiferromagnets due to scalar spin chirality. While the AHE itself bears the potential of application in electronic devices such as Hall sensors, quantization of the AHE can lead to exotic phenomena with potential for dissipationless electronics and quantum computing. Recently, a large AHE was observed in a collinear antiferromagnet CoNb3S6 [1]. The subsequent theories have indicated that the AHE in CoNb3S6 may be inherently related to the chirality associated with the crystal structure, a new mechanism for the anomalous Hall effect. Our recent experiment, however, suggests that the AHE is intrinsically related to the electronic band structure. In this talk I will present our recent results in which we have been able to tune the AHE by hole doping obtained in Co1-xFexNb3S6 samples. I will then discuss the importance of these results, which together with other recent related experimental findings [2] in CoNb3S6, suggest that quantization of the AHE can be achieved in CoNb3S6 by band tuning through optimal doping. [1] Ghimire et al. Nat. Commun. 9, 3975 (2018). [2] Tenasini et al, under review in PRX (2019). "

Abstract Number ANPA2020_0030
Author/s Dipendra Dahal (1), Godfrey Gumbs (2), Danhong Huang (3)
Title Effect of strain on plasmons, screening, and energy loss in graphene/substrate contacts
Affiliation/s North Carolina Central University (1) , North Carolina Central University (2), City University Of New York and Air Force Research Laboratory, Kirtland AFB (3)
Abstract " The combined effect due to mechanical strain, coupling to the plasmons in a doped conducting substrate, and the plasmon-phonon coupling in conjunction with the role played by encapsulation of a secondary twodimensional layer is investigated both theoretically and numerically. The calculations are based on the randomphase approximation for the surface response function which yields the plasmon dispersion equation that is applicable in the presence or absence of an applied uniaxial strain. We present results showing the dependence of the frequency of the charge density oscillations on the strain modulus and direction of the wave vector in the Brillouinzone.Theshieldingofadilutedistributionofchargesaswellastherateoflossofenergyforimpinging charges is investigated for this hybrid layered structure. "

Abstract Number ANPA2020_0032
Author/s Firoza Kabir (1) , M. Mofazzel Hosen 1, Xiaxin Ding 2, Christopher Lane 3, Gyanendra Dhakal 1, Yangyang Liu 1, Klauss Dimitri 1, Christopher Sims 1, Sabin Regmi 1, Luis Persaud 1, Yong Liu 4, Arjun K. Pathak 5, Jian-Xin Zhu 3, Krzysztof Gofryk 2, and Madhab Neupane 1
Title Observation of topological surface state in gadolinium-doped Sb2Te3
Affiliation/s Department of Physics, University of Central Florida, Orlando, Florida 32816, USA. (1) Idaho National Laboratory, Idaho Falls, Idaho 83415, USA. (2), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA (3), Ames Laboratory, US Department of Energy, Iowa State University, Ames, Iowa 50011, USA. (4), Department of Physics, SUNY Buffalo State, Buffalo, New York 14222, USA (5)
Abstract " Abstract hidden upon Author's request. "

Abstract Number ANPA2020_0033
Author/s Ganesh Pokharel (1) , G. Pokharel (2), H. Suriya Arachchige(2), G. Ehlers (3), Do Seunghwan (4), M. B. Stone (4), M. D. Lumsden (4), Zhang Hao (2), C. D. Batista (5), Y. Qui (3), R. S. Fishman (5), D. Mandrus(6), A. D. Christianson (3)
Title Inelastic neutron scattering study of the lacunar spinel GaV4S8
Affiliation/s The University of Tennessee (1) , Department of Physics and Astronomy, UTK (2); Neutron Technologies Division, ORNL; (3) Material Science and Technology Division, ORNL(4); NIST Center for Neutron Research, NIST, Gaithersburg, MD (5); Department of Material science and Engineering, UTK (6);
Abstract " Abstract hidden upon Author's request "


SESSION - VII: Bio/Soft Matter Physics

Abstract Number ANPA2020_0040
Author/s Kamal Dhakal
Title Restoring Vision to the Blind-Optogenetics
Affiliation/s Abbvie Inc.
Abstract " Abstract hidden under author's request."

Abstract Number ANPA2020_0043
Author/s Lalit Chudal (1), Nil Kanatha Pandey (1) and Wei Chen (1)
Title Copper-Cysteamine Nanoparticles as a Heterogeneous Fenton-Like Catalyst for Highly Selective Cancer Treatment
Affiliation/s The University of Texas at Arlington (1)
Abstract " Herein, for the first time, we report copper-cysteamine (Cu-Cy) nanoparticles having Cu1+ instead of Cu2+ as an efficient heterogeneous Fenton-like catalyst for highly selective cancer treatment. Initial measurements of Cu-Cy’s hydroxyl radical generation ability show that it behaves as a Fenton-like reagent in the presence of H2O2 (100 μM) at pH 7.4, and that its Fenton-like activity is dramatically enhanced under acidic conditions (pH 6.5 and 5.5). Notably, Cu-Cy exhibits high stability and minimal copper release during the Fenton-like reaction, demonstrating its potency as a heterogeneous Fenton-like catalyst with a low cytotoxic effect. Through extensive in vitro studies, Cu-Cy NPs are found to generate a significantly higher level of ROS, thereby causing significantly more destruction to cancerous cells than to normal cells without the need for exogenous additives, such as H2O2. To the best of our knowledge, the average IC-50 value of Cu-Cy to cancer cells (11 μg/mL) is the lowest among reported heterogeneous Fenton-like nanocatalyst so far. Additionally, compared to cancer cells, Cu-Cy NPs display substantially higher IC-50 value toward normal cells (50 μg/mL), suggesting high selectivity. Overall, Cu-Cy NPs can participate in heterogeneous Fenton-like activity with elevated H2O2 under acidic conditions to produce significantly higher levels of hydroxyl radicals in cancer cells when compared to normal cells, resulting in selective cytotoxicity to cancer cells. "

Abstract Number ANPA2020_0052
Author/s Nawal K. Khadka (1) , Witold K. Subczynski (2), Laxman Mainali (3)
Title Discrimination and Characterization of Cholesterol Bilayer Domain using Atomic Force Microscopy
Affiliation/s Department of Physics, Boise State University, Boise, Idaho, USA (1); Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA (2); Department of Physics, Boise State University, Boise, Idaho, USA and Biomolecular Sciences Graduate Program, Boise State University, Boise, Idaho, USA (3)
Abstract " Abstract hidden upon Author's request"

Abstract Number ANPA2020_0024
Author/s Deepak Koirala (1)
Title Determining RNA 3-dimensional structures using X-ray crystallography
Affiliation/s The University of Chicago (1)
Abstract " In addition to transferring genetic information, RNA performs a wide variety of functions to maintain biological homeostasis in different cellular environments. RNA molecules often fold into 3-dimensional architectures to perform their functions and therefore, understanding of their 3-dimensional structures help us to reveal how these molecules perform their functions and provide a key insight for developing targeted therapeutics. Among several biophysical methods, X-ray crystallography has been the most developed and most widely used method for determining the high-resolution structures of biomacromolecules including RNA molecules. However, RNA and RNA-protein complex structures represent only a small fraction of all deposited high-resolution structures in the protein data bank, underscoring the difficulties associated with the RNA crystallography. We have been developing RNA binding proteins, specifically synthetic antibodies, as chaperones for the RNA crystallography. Using this strategy, we have solved several crystal structures of antibody-RNA complexes where antibodies have been advantageous for the crystallization by mediating majority of the crystal contacts, trapping a specific conformation sampled by the target RNA and helping in initial phasing by serving as molecular replacement models. Many of our antibody-RNA modules are portable and can be easily engineered into an RNA of interest as affinity tags for wide variety of applications beyond crystallography such as RNA imaging and immunoprecipitation. We have also developed anti-RNA antibodies that specifically inhibits the translation mediated by a viral internal ribosome entry site, suggesting that anti-RNA antibodies themselves have potential as new class translation inhibitors for developing the antiviral therapeutics. "

Abstract Number ANPA2020_0058
Author/s Prakash Shrestha (1) ,Darren Yang (2), William M. Shih (3), and Wesley P. Wong (4)
Title Single-Molecule 3D Structure Reconstruction of a Protein Complex using DNA Nanoswitch Calipers
Affiliation/s Harvard Medical School and Boston Children's Hospital, Program in Cellular and Molecular Medicine, Boston Children’s Hospital. (1); Wyss Institute for Biologically Inspired Engineering, Harvard University. (2); Department of Cancer Biology, Dana-Farber Cancer Institute. (3); Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School. (4) ;
Abstract " Abstract hidden upon Author's request. "

Abstract Number ANPA2020_0042
Author/s Krishna Sigdel (1) ,Arthur G Roberts (2), Gavin M King (3)
Title Insights into Protein-Membrane Interactions via Atomic Force Microscopy
Affiliation/s Cal Poly Pomona (1); University of Georgia (2);, University of Missouri-Columbia (3);
Abstract " Understanding the interactions of proteins with the complex environment of cellular membranes is a fundamental problem in biophysics. These interactions are important because they determine the three-dimensional structure and ultimately the function of membrane proteins, a large class of pharmaceutically relevant macromolecules that reside within cellular membranes. Conventional biochemical methods have been used to study protein-membrane interactions but elucidating mechanistic details from such assays has proven to be challenging. Here, I will discuss a project focused on the cancer-related membrane protein P-glycoprotein (P-gp) that plays a major role in human disease and drug disposition because of its ability to pump a chemically diverse range of drugs out of the cell. Deciphering the drug-induced conformational changes is key to understanding the molecular basis of transport and to developing novel pharmaceuticals. We directly imaged individual P-gp transporters reconstituted into a lipid bilayer membrane and studied the protein structure and structural dynamics in physiological buffer solution. This work provides a foundation for future studies such as imaging the structural consequences of cancer drug binding to P-gp in near-native conditions. "

Abstract Number ANPA2020_0065
Author/s Raju Timsina (1) , Laxman Mainali (2)
Title Association of α-crystallin with the phospholipid membrane: A DLS study
Affiliation/s Department of Physics, Boise State University, Boise, 83725 USA (1); Department of Physics and Biomolecular Sciences Graduate Program, Boise State University, Boise, 83725 USA (2)
Abstract " α-crystallin, a significant protein of the vertebrate lens, associates to the eye lens membranes progressively with age and cataract formation. A clear understanding of α-crystallin association with the eye lens membranes, particularly involving phospholipids (PLs), remains lacking. In this study, we investigate the size of α-crystallin and its association with one-palmitoy-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) membrane by using dynamic light scattering (DLS). Phosphatidylcholine is the most abundant PL in the eye lens of short-life-span animals. Small unilamellar POPC vesicles prepared by using a rapid solvent exchange method were mixed with α-crystallin and incubated at 37 °C for 16 hours for probing the association of α-crystallin with POPC membranes. One of the key findings of this study was that with the increase in temperature, the hydrodynamic diameter of α-crystallin decreased by ~3 nm; however, there was an abrupt increase in its size above 60 °C, indicating the aggregation of α-crystallin. Also, the hydrodynamic diameter of α-crystallin at various concentrations (0.75 – 10 mg/ml) was measured. The hydrodynamic diameter remains the same (~ 26 nm) up to 5 mg/ml concentration; however, it increases at higher concentrations reaching ~28.5 nm at 10 mg/ml concentration. Moreover, α-crystallin started to aggregate above 60 °C, and the size of aggregate increased with an increase in temperature from ~60 °C to ~90 °C. However, when α-crystallin was incubated with membranes, the size of α-crystallin aggregate decreased with an increase in membrane concentration. We speculate that with an increase in membrane concentration, more and more α -crystallin binds to the membranes, preventing aggregation. It is likely that at a higher temperature, surface hydrophobicity of α -crystallin increases that enhance the binding of alpha-crystallin with membranes via hydrophobic interactions. Our results give fundamental insights into the understanding of the α-crystallin-membrane association. Acknowledgments: This work was supported by grant R01 EY030067 from the National Institutes of Health, USA. "

Abstract Number ANPA2020_0069
Author/s Ram Poudel (1, 2)
Affiliation/s International Association for the Integration of Science and Engineering (IAISAE) (1) , Institute of Engineering, Tribhuvan University, Nepal (2)
Abstract " Our civilization has depended largely on cooperation among human beings. However, our science is yet to figure out ‘How did cooperative behavior evolve?’ This question from ‘What don’t we know’ series from the Science journal has been awaiting physical reasoning for a long time. We generalize the classical field theories for an ensemble of human beings and propose a new theory. The social field theory formalizes the energy of an individual in the social field. We underpin this new energy as a physical basis for cooperation among human and the evolution of human society. A fundamental understanding of why cooperation evolved may have a resounding effect on our understanding of social, political and economic rationale. Indeed, Darwin uncovered some general rationale of the cooperation. However, the science of evolution doesn’t provide physical reasoning, and also not adequate for the 21st century human consciousness. Biologists are refining the Darwin’s ideas a bit by bit. Here, engineers aspire to uncover cooperative behavior in the terms of energy to be acknowledged by the learned societies. The human cooperation is not much different literally from cooperation that takes place between an electron and nucleons in a model of an atom. It is our consciousness that makes cooperative behavior special among social beings. Keywords: evolution, cooperation, society, social field theory, energetics "

Abstract Number ANPA2020_0077
Author/s Samuel Haralu (1) , Fathima Dhilhani Mohammed Faleel (2), Alberto Perez Galende (1), William Carbo (1), Steve Alston (1), Gary A. Lorigan (3), Indra D. Sahu. (1)
Title Probing Structural Dynamics of Potassium Channel Accessory Protein KCNE3 using EPR Spectroscopy and Molecular Dynamics Modeling
Affiliation/s Natural Science Division, Campbellsville University, KY, 42718. (1); Chemistry and Biochemistry Department, Miami University, OH, 45056., (2); Chemistry and Biochemistry Department, Miami University, OH, 45056., (3);
Abstract " KCNE3 is a single transmembrane accessory protein that modulates the voltage-gated potassium ion channel, KCNQ1. KCNE3 is expressed in the colon, small intestine, specific types of cells in the stomach, and all regions of the human heart including the left and right ventricles. Studies show that mutations on this protein are linked to several diseases like Long-QT syndrome, Atrial fibrillation, Manière’s disease, Cystic fibrosis, etc. Potential association with disease amplifies the importance of understanding the structural and dynamic properties of this transmembrane protein. So far, studies have been done in micelles and isotropic bicelles which give us insight into the functioning of this protein. However, these studies have not been performed in their native membrane environments which imply the potential for limited characterization. This study seeks to probe structural and dynamic properties of the transmembrane protein KCNE3 in its native mimetic environment. To achieve this, we have optimized sample preparation for successful over expression, purification, MTSL spin labeling, and incorporation of KCNE3 into POPC/POPG liposomes and performed CW-EPR experiments. Our Circular Dichroism (CD) data suggested better folding in lipid bilayers when compared to that in micelles. Our initial CW-EPR spectral line shape analysis and molecular dynamics simulation data suggested a slower motion of the protein in lipid bilayer environment when compared to that in micelles. This is consistent with previous structural studies of KCNE3. "

Abstract Number ANPA2020_0088
Author/s Swapnil Baral (1) , Lars Gundlach (1), Bjoern Baumeier (2), Edward Lyman (1)
Title Predicting Spectral Properties of Polarity Sensitive Dyes with QM/MM Simulation
Affiliation/s University of Delaware (1); Eindhoven University of Technology (2); University of Delaware (3);
Abstract " Lipophilic dyes such as laurdan and prodan are widely used in membrane biology due to a strong bathochromic shift in emission that reports the structural parameters of the membrane such as area per molecule. Disentangling of the factors which control the spectral shift is complicated by the stabilization of a charge-transfer-like excitation of the dye in polar environments. Predicting the emission therefore requires modeling both the relaxation of the environment and the corresponding evolution of the excited state. Here, an approach is presented in which (i) the local environment is sampled by a classical molecular dynamics (MD) simulation of the dye and solvent, (ii) the electronically excited state of prodan upon light absorption is predicted by numerical quantum mechanics (QM), (iii) the iterative relaxation of the environment around the excited dye by MD coupled with the evolution of the excited state is performed, and (iv) the emission properties are predicted by QM. The QM steps are computed using the many-body Green’s function in the GW approximation and the Bethe–Salpeter equation with the environment modeled as fixed point charges, sampled in the MD simulation steps. The comparison to ultrafast time-resolved transient absorption measurements demonstrates that the iterative molecular mechanics (MM)/QM approach agrees quantitatively with both the polarity-dependent shift in emission and the time scale over which the charge transfer state is stabilized. Together the simulations and experimental measurements suggest that the evolution into the charge transfer state is slower in amphiphilic solvents. "

SESSION - VIII: Bio/Soft Matter Physics

Abstract Number ANPA2020_0054
Author/s Nil Pandey (1) , Lalit Chudal (1) and Wei Chen (1)
Title Rapid and Efficient Degradation of Organic Pollutants by Catalytic Oxidation using Copper-Cysteamine Nanoparticles
Affiliation/s Department of Physics, The University of Texas at Arlington, Arlington, Texas 76019, USA (1)
Abstract " Copper-cysteamine (Cu-Cy) is a new nanoparticle that can be stimulated by ultraviolet light, X-ray, microwave, and ultrasound to produce various types of reactive oxygen species (ROS) for cancer and infectious disease treatment. Our recent studies showed that Cu-Cy nanoparticles (NPs) can be used for wastewater treatment as an efficient heterogenous catalyst, thereby adding one more important practical application of this interesting material. Herein, for the first time, we describe the beginnings of a detailed investigation of the use of Cu-Cy NPs with the assistance of hydrogen peroxide (H2O2) as an oxidizing agent for the oxidative degradation of organic contaminants for wastewater treatment. The effects of different operating parameters, such as amount of Cu-Cy, H2O2 concentration, and dye concentration, were also investigated in detailed way to determine the optimal operating conditions. Additionally, radical scavengers on the degree of degradation of RhB were explored. Overall, it is believed that Cu-Cy/H2O2 system studied in this work could be used in advanced oxidation processes towards the degradation of organic pollutants. "

Abstract Number ANPA2020_0047
Author/s Manoj Kumar Chaudhary (1) , Preeti Prajapati (2), Karnica Srivastava (2), Keila Facanha (3), Bhawani Datt Joshi (4), Poonam Tandon (2), Alejandro Pedro Ayal(3)
Title Structural, spectroscopic (IR and Raman) and physicochemical properties of Ricobendazole, from experimental and computational approach
Affiliation/s Central Department of Physics, Tribhuvan University, Kirtipur, Kathmandu, Nepal (1) ; Department of Physics, University of Lucknow, Lucknow 226007, India (2); Depertmento do Fisica, Universidade Federal do Ceará Fortaleza, CE, Brazil (3) ; Department of Physics, Siddhanath Science Campus, Tribhuvan University, Nepal (4);
Abstract " Abstract hidden upon Author's request "

Abstract Number ANPA2020_0013
Author/s Ankit BK (1) , Anup Subedi (2), Samrat Subedi (2), Kushal KC (2), Bishal Gautam (2), Damodar Koirala (3)*
Title Analysis of iron content in selected vegetarian food items in Pokhara.
Affiliation/s Tribhuvan University (1); Department of Chemistry, Prithivi Narayan Campus (TU affiliation), Pokhara Metropolitan City, Kaski (2) School of Engineering, Pokhara University, Pokhara Metropolitan City, Kaski (3)
Abstract " Analysis of iron content of 10 vegetarian food samples belonging to three different food (spices, lentils and locally available vegetables) categories was the objective of this study. UV-Vis spectrophotometry was used to estimate and evaluate the levels of iron in the studied vegetables, lentils and spices. Vegetarians are more vulnerable to the deficiency of iron as they consume non-heme iron which needs to be altered before it can be absorbed by the body. While, non-vegetarians are rarely a victim of iron deficiency as their diet consists of meat through which they consume proteins like hemoglobin and myoglobin directly in the unaltered form. Inevitably, there is a need to measure the amount of iron in the vegetarian food products to determine which food sources are rich in iron, so that they may be consumed during iron deficiency. Spectrophotometric technique of analysis was used to determine the iron content. It works on principle of the Beer-Lambert law. From the results thus obtained, the maximum contribution was shown by spices and condiments towards the dietary iron content whereas the minimum contribution was shown by vegetables and lentils. Keywords: Beer-Lambert law, Iron content, Vegetables. "

Abstract Number ANPA2020_0063
Author/s Rajendra Prasad Koirala (1) , Prem Prasad Chapagain (2), Narayan Prasad Adhikari (1)
Title Repair Mechanism of Methyl Lesion in DNA Transferring Methyl Adduct to O6-alkylguanine-DNA alkyl transferase (AGT)
Affiliation/s Central Department of Physics, Tribhuvan University, Nepal (1); Department of Physics, Florida International University, Miami, FL, USA, (2)
Abstract " The molecular dynamics (MD) study of protein-DNA complex system reveals the theoretical insight of inter-molecular interaction among the protein residues and DNA nucleotides. DNA binding proteins perform several biochemical interactions with DNA in living organisms. Out of these, we have studied the interaction mechanism of DNA repair protein, O6-alkylguanine-DNA alkyl transferase (AGT) with methyl DNA at O6-point of guanine base during the methyl damage transfer process. Umbrella sampling method has been utilized to investigate the change in free energy of the interaction in two AGT-DNA non-covalent complexes, one with methylated GUA in DNA (system-I) and the other with methylated CYS145 in AGT (system-II). The system-I and system-II do as pre- and post-complex structures representing the methyl damage transfer mechanism. The estimated free energy in two complexes, clearly shows that AGT serve as the methyl damage repair agent in DNA. Our studies allow the computational investigation of DNA damage transfer mechanism and may explore future approach for its use as a target for cancer therapeutics. "

SESSION - IX: Data Science

Abstract Number ANPA2020_0105
Author/s Pere Miro
Title Quantum Computing: Basics and Chemistry Perspectives
Affiliation/s University of South Dakota

Abstract Number ANPA2020_0007
Author/s Aman Ganeju (1) , Dibakar Sigdel (2)
Title Implementation of Quantum Fourier transform on Shor's algorithm
Affiliation/s Khwopa College, Bhaktapur, Nepal (1) , University of California Los Angeles (2)
Abstract " Integer number factorization has been known to be inefficient and have exponential or by-far super-polynomial time complexity for classical computer. Shor's algorithm is a quantum algorithm that can factor a given number N in polynomial time by exploiting the correspondence of factoring problem with period finding problem on a quantum computer. Shor's algorithm specifically uses quantum Fourier transform as a key component for reducing the complexity of the problem to BQP class. This paper introduces quantum Fourier transform and technique of Shor's algorithm using modular exponentiation. "

Abstract Number ANPA2020_0104
Author/s Dibakar Sigdel
Title Data science in personalized medicine
Affiliation/s University of California Los Angeles
Abstract "Personalized medicine or precision medicine is a medical model based on separating people into different groups with medical decisions, practices, interventions and/or products which are tailored to the individual patient based on their predicted response or risk of disease. In this talk, I will present the data sources and data science, Machine learning and Artificial Intelligence(AI) approach implemented in the direction of achieving the future goal of Personalized Medicine. Various data sources are being systematically designed by world renowned organizations (e.g., WHO, NLM) for international disease classification, gene database, protein database etc. The main focus of this talk will be to present in brief how different data sources and techniques of modern computation can be brought up together in the single platform for building applications for high precision medicine. "

SESSION - X: Condensed Matter

Abstract Number ANPA2020_0105
Author/s Tula Paudel
Title Spin Filtering in Two-Dimensional Magnetic Tunnel Junctions
Affiliation/s University of Nebraska–Lincoln, USA
Abstract "The recently discovered two-dimensional van der Waals magnets have attracted a lot of attention from the research community. In my presentation, I will briefly survey the field, and discuss the unique properties they display and the applications they drive using a prototypical magnetic semiconductor, Chromium triiodide (CrI3). The first-principles methods based on density functional theory are reliable methods for exploring spin-dependent transport in tunnel junctions. In a particular density functional theory study1 of a tunnel junction involving face-centered cubic Cu (111) electrodes and a CrI3 tunnel barrier, We find about 100% spin polarization of the tunneling current and tunneling magnetoresistance of about 3,000% associated with a change of magnetic ordering in CrI3, consistent with experimental observations. We interpret these results terms of the spin and wave-vector dependent evanescent states in CrI3 which control the tunneling conductance. Our results elucidate the mechanisms of spin filtering in CrI3 tunnel junctions and provide important insights for the design of magnetoresistive devices based on 2D magnetic crystals.
1. Paudel TR, Tsymbal EY. Spin Filtering in CrI3 Tunnel Junctions. ACS Appl Mater Interfaces. 2019;11(17):15781-15787."

Abstract Number ANPA2020_0036
Author/s Hari Krishna Neupane (1) , Narayan Prasad Adhikari (2)
Title Structure, Electronic and Magnetic Properties of 2D Graphene-Molybdenum diSulphide (G-MoS2) Heterostructure (HS) material with Vacancy Defects at C Sites
Affiliation/s Amrit Campus TU, Kathmandu Nepal (1); Central Department of Physics TU, Kathmandu Nepal (2);
Abstract " Abstract not displayed upon Author's request"

Abstract Number ANPA2020_0041
Author/s Karan Giri (1) , Ashok Bhandari (1)
Title Study of damage profiles and calculation of energy loss in Gallium ion implantation on Germanium substrate.
Affiliation/s Tri-Chandra Multiple Campus, Tribhuvan University (1)
Abstract " Abstract: Computational calculation of energy loss and damage profiles when implanted by gallium ions on amorphous germanium during ion implantation had been carried out. The required energies for doping of gallium ion on germanium, in order to obtain maximum damage at 600 Å, were calculated using SRIM; Stopping and Range of Ions in Matter. These energies when implanted independently on germanium causes the production of germanium recoils, vacancy-interstitial pairs, and phonons during the collision process. For 130.000 keV gallium ion, the energy used for ionization, phonon production and vacancies creation are 37.713 keV (29.01% of incident energy), 90.006 keV (64.29% of incident energy) and 8.710 keV (6.7% of incident energy) respectively. The amount of target displacement, replacement collisions and vacancies were also evaluated. Doping of gallium ions on germanium also reveals that the energy loss due to nuclear stopping was greater than electronic stopping. Key Words: implantation, doping, ionization, phonons, target displacement, nuclear stopping "

Abstract Number ANPA2020_0060
Author/s Pratikshya Gautam (1) , Aabiskar Bhusal (2)
Title Study On Spin/States Of Silican Carbide Nanotube
Affiliation/s Prithivi Narayan Campus, Tribhuvan University (1) , Physics Research Initiatives, pokhara Nepal (2)
Abstract " Abstract hidden upon Author's request "

Abstract Number ANPA2020_0062
Author/s Raj Kumar Rai (1) , G.C. Kaphle (2), O.P. Niraula(3)
Title First-Principle Study of the Filling Control Effect of Electronic Structure and Transport Properties of Heterostructure of (La,Ca)VO3
Affiliation/s Central Department of Physics, Kirtipur Campus, Tribhuvan University, Nepal (1); Patan Multiple Campus, Tribhuvan University, Nepal (2) ; Central Department of Physics, Kirtipur Campus, Tribhuvan University, Nepal (3)
Abstract " The transition metal oxides (TMOs) heterostructures in their nanodimensions exhibit very rich and promising novel physical and chemical behaviors for scientific research and technological innovation. The investigations of electronic and atomic reconstructions of pristine LaVO3 and CaVO3 have revealed that the former one is the Mott-insulator whereas the latter one is the correlated metal. We have implemented the interfacial electrostatic bonds to investigate the possible growth of complex TMOs heterostructures of nearly infinite stable chemical combinations. With this vast possibility for tuning and combining properties, we can achieve various desirable change of many currently used electronic, optical and energy devices. The effect of different levels of filling controls on electronic structure and transport properties of heterostructure of supperlattices of LaVO3 and CaVO3 are studied by using the first-principle method with GGA approximation of WIEN2k frameworks. A patching software, BoltzTrap 1.5 is used for predicting the transport behaviours, such as electrical conductivity, thermal conductivity, Seebeck coefficient, transport coefficient, magnetic susceptibility etc. are observed for different levels of filling control. Furthermore, the dynamical mean field theory (DMFT) is implemented for realistic calculation of electronic structure of the materials. The spectral density of Matsubara frequency, which corresponds to density of states (DOS) for the system is investigated using the Maximum Entropy data analysis method for the resulting DMFT data obtained with ALPS-package and ABINIT package. The characteristics of spectral density of LaVO3 with U=5.0eV reveals that LaVO3 is the Mott-insulator. The result is consistent with the experimental observation of angle-resolved photoemission spectroscopy (ARPES). Keywords: Complex TMOs, DMFT, GGA, Heterostructure, Strongly Correlated System Acknowledgements: The authors are thankfully acknowledged to UGC for the support. "

Abstract Number ANPA2020_0008
Author/s Amba Datt Pant (1)
Title Life Science Studies with Muons
Affiliation/s IMSS, KEK, Japan (1)
Abstract "Positive muon is a spin half elementary particle lies in the second generation leptons in standard model of particles. It has been used as a sensitive magnetic (spin) probe for study of life and materials sciences. Due to its special characteristics – 100% polarized and asymmetric decay to positron, it provides information about local electronic and spin states of material in which it stops.
Here, the applications of positive muon to understand the life related phenomena are presented. The mass of muon is 1/9th of proton. The bound state of muon and an electron is known as muonium which is like a light isotope of hydrogen. Muonium is ~ 100 times more sensitive than the muon. The relaxation of muon and its charge states in materials provide information about the interested phenomena. The detection of molecular oxygen in biological aqueous solutions (hemoglobin, serum, albumin, tris-buffer saline), electron transfer in proteins (cytochrome c and pseudoazurin copper protein) and future perspectives using microbeam of muon (transmission muon microscope) will be discussed. "