Nanosphere Lithography for Nano Optical Applications


Many different techniques are available to create nanopatterns in nanoscale devices. However, a few are flexible and inexpensive enough to be practical in the nanotechnology. Here, we study the nanosphere lithography (NSL) based on a self assembly of microspheres. Using this technique, we have developed various patterns in metallic films, ranging from honeycomb arrays of “quasi-triangles" to circular holes. These various patterns have been used subsequently either as nano optical structures directly, with remarkable optical and plasmonic properties, or as substrates for further nanoprocessing. In one such nano-processing, the “quasi-triangle” patterns were used as a catalyst for carbon nanotube growth. The resulting aligned arrays of carbon nanotubes were employed in nanocoax solar cells. In another nanoprocessing, the arrays were used as masks for electrodeposition. In addition to the nano processing and measurements, we have employed the FDTD computer simulations, to develop a full understanding of the nano optical and plasmonic properties of the developed structures.

Trilochan Paudel, PhD*

*Trilochan Paudel has been working as a Technology Development Engineer at Intel Corporation, Oregan, USA since 2011. He has a PhD in Physics from Boston College, USA and MSc in physics from Tribhuvan University. He has authored more than ten research articles in international peer reviewed journals. His research area includes, but not limited to, thin film in Semiconducting World, Solar Cell, Lithography and its applications for Nano Optical Devices.

Date: 21 September, 2019
04 Asoj, 2076


A Study of the Occurrence Rate and Energy of Flares on M5-L5 Spectral Types


We used NASA Kepler K2 mission short cadence (~1 minute) and long cadence (~30 minutes) data to study the white light flare (WLF) rates of low mass objects with spectral types in the range M5-L5. We analyzed WLFs of 42 objects using short cadence data and ~500 objects using long cadence data. They were observed by K2 mission in different campaigns (Campaign 3 - Campaign 18). We observe a higher flare rate in the mid-M dwarfs which are fully convective. The flare rate decreases with the decrease in effective temperatures. In an energy range of 1029 - 1033.5 ergs, the flare energies follow a power law with slopes in range -(1.3 - 2.0). The cooler objects tend to have shallower slopes. We find that the flares are also produced by objects with spectral types as late as L5. The occurrence of super- flares on targets with spectral types as late as 15 suggests that either they have strong magnetic fields comparable to those in the warmer targets or the volumes associated with flares are larger on cooler targets, or a combination thereof. In addition, we characterized superflares (flares with energy >1033 ergs) on young brown dwarfs, late-M dwarfs (M8 and M9 spectral types) and early L dwarfs. The results will provide significant inputs into exoplanet atmosphere and climate models which are aimed at constraining the habitability of M dwarf planets.

Rishi R. Paudel, PhD*

*Rishi R. Paudel is a postdoctoral fellow at NASA, Goddard Center, USA. He has a PhD in Astronomy from the University of Delaware, USA and MSc in physics from Tribhuvan University. He has authored more than ten research articles in international peer review journals. His research area includes, but not limited to, Magnetic activity, astrometry, kinematics, atmospheres and formation of low mass stars and brown dwarfs.

Date: 08 August, 2019
1 Bhadra, 2076


Seasonal Variability of Air Pollution Transportation Over Nepal


The present study investigates various types of aerosol components over Nepal by using Inversion Aerosol optical data of 2017 to 2019 over Pokhara obtained from aerosol optical data observed by CIMEL Sun Photometer. Backtrajectory analyses using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model has been used to investigate the transboundary effect on major air masses over Pokhara. Fine aerosols are significantly loaded into the atmosphere during the pre-monsoon and post monsoon season. The air mass trajectory analysis, along with different aerosol optical properties parameters, volume size distributions in different months of different seasons, single scattering albedo (SSA), absorption angstrom exponents indicate that the major particulate matters are associated with urban industrial emissions, fossil fuel burning and road/soil dust. An analysis of seasonal variations in the AERONET retrieved SSA (0.80-0.89) values suggested a predominance of urban industrial, vehicular and dust aerosols over Pokhara.

Rudra Aryal, PhD*

*Rudra Aryal was born in Palpa. He has received his Ph.D. degree in Physics from the University of Miami, Florida, USA and his M.Sc. and B.Sc. degrees in Physics from Tribhuvan University, Kritipur and Trichandra College Kathmandu, Nepal. He is a former joint secretary of Nepal Physical Society (2000-2002/ 2002-2004). Currently, he is Professor of Physics at Franklin Pierce University, New Hampshire USA. His research focuses on air pollution especially on the interaction of solar radiation with surface level and column integrated atmospheric pollutant (aerosol) particles.

Date: 23 May, 2019
8 Jestha, 2076


Forest Carbon Stock Estimation in Nepal Integrating LiDAR, Field plots, and Satellite Imagery


Forest measurement for purposes of mitigating climate change through carbon capture by forests call for increasingly frequent forest measurement campaigns that need to balance cost with accuracy and precision. Often this implies the use of remote sensing-based measurement methods. For any remote-sensing based methods to be accurate, they must be validated against field data. A method is present that combines field measurements with two layers of remote sensing data: sampling of forests by airborne laser scanning (LiDAR) and Landsat imagery. The framework presented here is called Lidar-Assisted Multi-source Programme—or LAMP—for Above Ground Biomass estimation. The method splits the biomass estimation task into two separate stages: forest type stratification from Landsat imagery and mean biomass density estimation of each forest type by LiDAR models calibrated on field plots. The LAMP method has been applied to a 2 million hectare area in 12 districts of Southern Nepal, the Terai Arc Landscape or TAL to calculate the emission Reference Levels (RLs) that are required for the UN REDD+ program that was accepted as part of the Paris Climate Agreement.

Basanta Gautam*

*Basanta Gautam is a manager of Forestry Department at Arbonaut Ltd. Finland. He is permanent resident of Pokhara. He has Master of Science in Agriculture and Forestry from the University of Eastern Finland and Master of Science in European Forestry from University of Lleida, Spain. He has authored four books and more than ten peer reviewed research articles. His research area includes, but not limited to, Cimate Change, GIS, Remote Sensing. He has experience of working in various research missions to India, Thailand, Cambodia, Mexico, South Africa, Qatar, Poland, Norway, Sweden, the Netherlands, USA, Italy, Australia, Cameroon, Uganda, Sri Lanka, Germany

Date: 16 March, 2019
2 Chaitra, 2075


Particulate Vaccine Adjuvants: A Brief Overview


Vaccination is a better way to prevent infectious diseases. Traditional vaccines are effective and unsafe; however, subunit vaccines are less effective and safe. Thus, vaccine adjuvants are used to boost immunogenic responses of subunit vaccines. Emulsions, liposomes, polymeric nanoparticles and inorganic nanoparticles are commonly used particulate vaccine adjuvants. In this talk, I will try to introduce particulate vaccine adjuvants highlighting current status and future prospects.

Rakesh Bastola*

*Rakesh Bastola, has completed MS in Pharmacy from Keimyung University, Republic of Korea as Korean Government Scholarship Grantee. He studied and worked under the supervision of Assoc. Prof. Sangkil Lee. He completed B. Pharm. from Pokhara University. Till date he has registered a patent and published 3 papers in reputed peer-reviewed journals.

Date: 01 December, 2018
15 Mangsir, 2075