Variation of dust properties around carbon rich AGB star- IRAS 04427+4951 using IRIS, AKARI survey

Interstellar dust properties using far-infrared bands analyze nature around asymptotic giant branch stars and stellar objects. Here, we present physical properties around the cavity region across an AGB star named IRAS 04427+4951 Sky View Observatory of IRIS, AKARI map, SIMBAD, Aladin v2.5, and Gaia Archive. The average color temperature and mass are 23.48 ± 0.009 K, 3.55×1027 kg (1.79× 10-3 Mʘ ) in IRIS data and 14.89 ± 0.004 K and 5.34×1028 kg (2.69 × 10-2 Mʘ ) from AKARI data. The size of isolated cavity-like structure around the AGB stars of 45.67 pc × 17.02 pc and 42.25 pc × 17.76 pc, respectively. The visual extinction is to be in the range of 3.2×10-4 to 4.3×10-4 mag in and 4.5 × 10-3 to 7.4×10-3 mag. The inclination angle is 86.150 and 93.920. The method and results we present developed can for the study of astrochemistry of interstellar medium. BIBECHANA 18 (2) (2021) 154-163

Synthesis of antioxidative anthraquinones as potential anticancer agents

Antioxidant and antibacterial activities of natural anthraquinones namely chrysophanol (1) and emodin (2), and synthesized anthraquinones viz. 2-methylanthraquinone (3), anthraquinone (4), 2-bromoanthraquinone (5), rubiadin (6), chrysophanol diacetate (7), rubiadin diacetate (8) and 1,8-dimethoxy-3-methylanthraquinone (9) were investigated. Anthraquinones 9, 3, 6, 5 and 2 exhibited a high DPPH• radical scavenging capacity (IC50 = <500 μg/mL) showing their therapeutic potentiality for the treatment of cancers. These anthraquinones 1-9 have also displayed a weak to moderate antibacterial activity against Bacillus subtilis. Chrysophanol diacetate (7) including emodin (2) have been appeared as the valuable antibacterials. BIBECHANA 18 (2) (2021) 143-153

Muonium behavior in N-acetylglycine-N-methylamide

In muon spin rotation and relaxation (mSR) method, theoretical work using first-principles calculations helps to understand the stopping sites and charge states of muon in the sample materials. To support the mSR measurement on protein and DNA, a systematic first-principles study starting from the constituents of the protein has been performed. In this work, the behavior of muonium (Mu = m+e-, bound state of a muon and an electron which is like a light isotope of H atom with similar chemical properties) in a N-acetylglycine-N-methylamide (AGMA), a part of peptide bond, is presented. It is found that the stopping site of Mu is around O of unsaturated bonds between C and O in the AGMA. Further calculations towards whole protein and DNA will be performed to support mSR studies. BIBECHANA 18 (2) (2021) 138-142

A study of dust structure nearby white dwarf WD1334-678

A low flux density region nearby white dwarf WD1334-678 in the 140 µm AKARI survey maps has been systematically searched and found a far-infrared cavity centered at R.A. (J2000) = 13h38m14.4s, Dec.(J2000) = −68◦40’42”, in which minimum flux is 19.5 MJy/sr at 90 µm wavelength. The physical properties (Size, dust color temperature, dust mass) and thermodynamic property (Planck function distribution) of the cavity using 140 µm and 90 µm AKARI survey data. The size of the cavity is found to be 0.17◦× 0.12◦ has been presented. The dust color temperature is found in the range 17.70 ± 0.01 K to 18.81 ± 0.01 K. The Plank function distribution along major and minor diameters shows a very good agreement with sinusoidal fitting. The period of oscillation of dust particles along major and minor diameters are 3.2 Wm-2Sr-1Hz-1arcmin-1and 1.6 Wm-2Sr-1Hz-1arcmin-1, respectively. BIBECHANA 18 (2) (2021) 130-137

Wavelet and cross correlation analysis on some climatology parameters of Nepal

This study has been performed to understand the relationship between sunspot numbers (SSN) with climatology related parameters like temperature and rainfall from 1901 to 2016. The spectral characteristics of sunspot numbers, temperature and rainfall have been observed using continuous wavelet transform. Cross-correlation analyses were also performed to find any relation among temperature, rainfall, and sunspot numbers. The 9–11 year periodicity of sunspot numbers confirmed by wavelet transform in annual scale. The periodicity of high-frequency signals is identified between 4 to 11 years whereas the low frequencies signal is found throughout the periods of observation for temperature. Similarly, it is clear that there is more concentration of power between 8–16 years for rainfall. Cross-correlation analysis shows that the sunspot numbers is highly correlated with rainfall and temperature (correlation coefficient ~ 0.8054). The time lag relationship resulted in the almost simultaneous linear relationship between the temperature, rainfall, and the SSN tendency. The development of convective motions over the subtropics might be affected by the time rate of change of SSN combined with the surface temperature changes of diverse time scales. The convective motions were mostly controlled by the available amount of water vapor and the stability of the atmosphere that had a strong connection with the heat capacity of the concerned region. To produce more authentic findings for policy implications, further comprehensive and appropriate research can be undertaken and implemented in this very important field. BIBECHANA 18 (2) (2021) 105-115

Effects of lightning as a disaster in Himalayan region

In Nepal, the main disasters are floods, lightning, fire, epidemics, and landslides. Among the several disasters in the Himalayan region, lightning is an important one. Because of the short distance (about 160 km) between the low land and peak Mount Everest from South to North, there is a variation of about 950C temperature in these regions. The topographical features of the southern slopes and variation of temperature within this short distance influences the features of lightning and in this scenario, we get the positive cloud to ground lightning frequently which is more dangerous for human beings, animals, and property. In the Himalayan region, thunderstorms occur near the mountains due to which more positive charge can easily transfer from cloud to ground. Hence positive lightning occurs in the Himalayan region. The majority of the lightning-affected people are unaware of lightning safety and they should know the measures to protect life and property from lightning hazards. Hence by conducting awareness programs for the people of potential hazard areas, the number of injured people can be reduced as well as electrical, medical, military equipment can be somewhat protected from lightning. BIBECHANA 18 (2) (2021) 116-128

Surface air temperature trends in Kathmandu Valley for 2011-2017

In this study, we reviewed the maximum and minimum temperature trends of the Kathmandu valley over the period of 2011-2017. In addition, the average monthly temperature trends were studied annually for the same period, with the data made available from the Department of Hydrology and Meteorology (DHM) of Nepal. The annual temperature trended in the same direction, with winter temperatures being lower and summer temperatures being higher. The annual average minimum and maximum air temperature trends were found to be slightly rising at 0.097˚C/year and 0.04˚C/year, respectively. The mean air temperature in Kathmandu valley is increasing at a rate of 0.06 degrees Celsius per year, with 2016 being the warmest year and 2012 being the least warm, with annual mean temperatures of 19.82˚C and 19.32˚C, respectively. The temperature difference is much smaller in the summer (less than ~12˚C) than in the winter. BIBECHANA 18 (2) (2021) 95-104

GPS TEC Scintillations and TEC depletion as seen from Hetauda and NAST, Nepal for 2016

We analyzed Global positing System Total Electron Content (GPS-TEC) data of stations Hetauda (27.414 0N and 85.051 0E) and NAST (27.656 0N and 85.327 0E), Nepal which are a part of UNAVCO.We obtained the variation of rate of TEC index (ROTI) and S4 index throughout the year 2016 for the two stations involved for the 32 all the Pseudo-Random Noise (PRN) numbers barring PRN number 4 which was inactive throughout the year. We chooses two stations data which are almost 40 km in distance and correlated the value of ROTI index with ROTI index and S4 index with S4 index and found that the ROTI index of Hetauda is well correlated with ROTI index of NAST with the highest being 94% for PRN 10 and the lowest being -13% for PRN 1. An extremely low correlation between S4 index of Hetauda and S4 index of NAST was observed with the highest correlation being 8% in PRN 3, 32 and the lowest correlation of -15% in PRN 12. BIBECHANA 18 (2) (2021) 87-94

Morphological analysis of Cu substituted Ni\Zn in Ni-Zn ferrites

Cu substituted Ni in Ni0.5-xCuxZn0.5Fe2O4 (x = 0, 0.05, 0.1, 0.15 and 0.2) samples and Cu substituted Zn in Ni0.5Zn0.5−xCuxFe2O4 (x = 0, 0.05, 0.1, 0.15 and 0.2) is synthesized using the sol-gel auto-combustion process. Recently, we have carried out their structural analysis using XRD and FTIR and found a cubic spinel structure. In this paper, we have studied their morphological and compositional structure with the help of a Scanning Electron Microscope (SEM) attached with an Energy Dispersive Spectrometer (EDS). The comparative study shows that the grain size of Cu substituted Ni is greater than Cu substituted Zn in Ni-Zn ferrite. These smaller grain-sized ferrites are preferred for many microstructural applications. Depending on the available magnetic field, sintering temperature, and atmosphere, they can have different nucleation, and hence their application mode is different. They can have a critical concentration that can tune their properties. The EDS attached with the SEM confirmed the proper composition of samples. BIBECHANA 18 (2) (2020) 80-86

Electronic and magnetic properties of defected MoS2 monolayer

It is interesting to understand the effect of defects in 2D materials because vacancy defects in 2D materials have novel electronic and magnetic properties. In this work, we studied electronic and magnetic properties of 1S vacancy defect (1Sv-MoS2), 2S vacancy defects (2Sv-MoS2), 1Mo vacancy defect (Mov-MoS2), and (1Mo & 1S) vacancy defects ((Mo-S)v-MoS2) in 2D MoS2 material by first-principles calculations within spin-polarized density functional theory (DFT) method. To understand the electronic properties of materials, we have analyzed band structures and DOS calculations and found that 1Sv-MoS2 & 2Sv-MoS2 materials have semiconducting nature. This is because, 1Sv-MoS2 & 2Sv-MoS2 materials open a small energy band gap of values 0.68 eV & 0.54 eV respectively in band structures. But, in Mov-MoS2 & (Mo-S)v-MoS2 materials, energy bands around the Fermi level mix with the orbital’s of Mo and S atoms. As a result, bands are split and raised around and above the Fermi energy level. Therefore, Mov-MoS2 & (Mo-S)v-MoS2 materials have metallic nature. We found that MoS2, 1Sv-MoS2 & 2Sv-MoS2 materials have non-magnetic properties, and Mov-MoS2 & (Mo-S)v-MoS2 materials have magnetic properties because magnetic moment of MoS2, 1Sv-MoS2 & 2Sv-MoS2 materials have 0.00 µB/cell value and Mov-MoS2 & (Mo-S)v-MoS2 materials have 2.72 µB/cell & 0.99 µB/cell respectively. Therefore, non-magnetic MoS2 changes to magnetic Mov-MoS2 & (Mo-S)v-MoS2 materials due to Mo and (1Mo & 1S) vacancy defects. The magnetic moment obtained in Mov-MoS2 & (Mo-S)v-MoS2 materials due to the distribution of up and down spins in 4p, 4d & 5s orbitals of Mo atoms and 3s & 3p orbitals of S atoms in structures. The significant values of the magnetic moment are given by distributed spins in 4d orbital of Mo atoms and 3p orbital of S atoms. BIBECHANA 18 (2) (2021) 68-79