Authors:S. K. Sharma, P. R. Dhungel, U. Khanal Pages: 1 - 5 Abstract: Behaviour of the Dirac particle in Coulomb like field in FLRW space is investigated. Firstly, the Maxwell equations, in terms of the vector potentials are solved to identify the Lorentz and Coulomb like gauges. The radial Coulomb like potential is solved in terms of Legendre functions. Then the Dirac equation is generalized to include this potential and the angular part is separated and solved. The radial and temporal parts of the mass less case is also separated and solved. But the massive case remains coupled. This is still reduced to the case where the Dirac particle can be represented as being in a combined gravitational and electric potential. This effective potential is found to develop an attractive well, which may require a revisit to the recombination era. PubDate: 2021-02-15 DOI: 10.3126/sw.v14i14.34975 Issue No:Vol. 14, No. 14 (2021)
Authors:Ramon Carbó-Dorca Pages: 6 - 13 Abstract: The present paper uses the LCAO MO theory formalism. The structure of the first order electronic density function is decomposed in two kinds of quantum polyhedra to discuss the behavior of quantum atomic populations. Among the many aspects one can consider about atomic populations here, the quantum mechanical structure of the density function is taken as the most important characteristic to think about. Apart of the usual one-electron basis set, centered in the molecular atoms, there is also discussed the possibility that the three-dimensional space where the molecular structures are described can be also the site of basis functions centered in points non-coincident with atomic positions. PubDate: 2021-02-15 DOI: 10.3126/sw.v14i14.34976 Issue No:Vol. 14, No. 14 (2021)
Authors:Mahendra Thapa, Mark Rance Pages: 14 - 20 Abstract: The coarse-grained protein modeling tool, Cabs-flex, is feely available online server; it is based on the CABS model in which each residue of a protein has been represented by four points. The server was used for the protein Calbindin D9k in it’s doubly calcium loaded state: small and single domain protein of the EF-hand family. Twelve representative structures, in all-atom format corresponding to each cluster, were also downloaded along with trajectories, ready-made plots, images, video, data files of Cα RMSD, atomic fluctuation and GDT_TS. In the present study, simulated Cα atomic fluctuations for residues of the protein was compared with the experimental results and also correlated with the respective Cα RMSD and GDT_TS. PubDate: 2021-02-15 DOI: 10.3126/sw.v14i14.34977 Issue No:Vol. 14, No. 14 (2021)
Authors:Bhawani Datt Joshi, Ghanshyam Thakur, Manoj Kumar Chaudhary Pages: 21 - 30 Abstract: In this work, quantum chemical study on a natural product ergoline has been presented using density functional theory (DFT) employing 6-311++G(d,p) basis set. A complete vibrational assignment has been performed for the theoretical FT-IR and Raman wavenumbers along with the potential energy distribution (PED) with the result of quantum chemical calculations. The structure–activity relationship has been interpreted by mapping electrostatic potential surface (MEP). Graphical representation of frontier molecular orbitals with their energy gap have been analyzed theoretically for both the gaseous and solvent environment employing time dependent density functional theory (TDDFT) employing 6-31G basis set. PubDate: 2021-02-15 DOI: 10.3126/sw.v14i14.34978 Issue No:Vol. 14, No. 14 (2021)
Authors:Manish Man Shrestha, Bibek Ropakheti, Uddhav Bhattarai, Ajay Adhikari, Shreeram Thakur Pages: 31 - 36 Abstract: In today’s world, it is necessary to monitor structures for possible damages. A failure to monitor the structures properly can cause structural catastrophe. Many researchers have worked on the low-power ultrasonic device to monitor the structures. In this research, we present an intelligent ultrasonic device (IUD) to monitor and detect the damages on the structures. The device uses microcontroller, actuator interface circuit, sensor interface circuit and radio frequency (RF) modem. The microcontroller has in-built high-speed analog-to-digital converter (ADC), digital-to-analog converter (DAC) and floating-point unit for signal processing. The controller generates the tone-burst signal and sends it to actuator interface circuit. The actuator interface circuit conditions the received signal from the microcontroller and drives the Piezoelectric Transducer (PZT) actuator. The actuator generates an ultrasonic wave in the structure. The wave is then sensed by PZT sensors. The sensor interface circuit selects the signal from desired PZT sensor and sends it to the microcontroller for further processing. The microcontroller digitizes the signal and computes the damage index and only if the damage is severe, it will send data wirelessly to the nearby PC. To test the device, iron specimen was prepared, PZT actuator and PZT sensor was mounted on it. The artificial crack was then induced on the specimen. The ultrasonic wave was then collected from the structure. By analyzing the ultrasonic wave, the device successfully detected the induced crack in the structure. The future work will be to use GSM modem so that the device can be monitored in the real time from the remote location. PubDate: 2021-02-15 DOI: 10.3126/sw.v14i14.34979 Issue No:Vol. 14, No. 14 (2021)
Authors:Purnima Bajracharya, Sabita Shrestha Pages: 37 - 43 Abstract: Four coordinated Nickel and six coordinate Cobalt complexes of type [Ni (HBH)2]. 2Cl, and Co (HBSH)2Cl2]Cl.2H2O [2-HBH=2-Hydroxybenzoic acid hydrazide] respectively were synthesized. The coordination behavior of 2-HBH in complexes have been suggested on the basis of analytical and spectroscopic techniques, where the ligand is coordinating to metal through oxygen of carbonyl and nitrogen of terminal NH2 group. All the complexes are coloured and non-hygroscopic. The compositions of complexes were established on the basis of various analytical procedures. The molar conductance value shows 1:1 electrolyte in Co (II) complex and 1:2 in Ni (II) complex. The electronic spectral studies showed the square planner geometry around Ni(II) and octahedral geometry around the Co (II) ion. The optical band gap energy of complexes was derived from electronic spectra the value of which underlies the range of semiconductor materials. PubDate: 2021-02-15 DOI: 10.3126/sw.v14i14.34981 Issue No:Vol. 14, No. 14 (2021)
Authors:Shriram Sharma Pages: 44 - 50 Abstract: Frequency domain information were extracted from the time domain electric fields pertinent to the lightning positive return strokes applying Fourier transform and Wavelet transform. The electric field radiated by positive ground flashes striking the sea were recorded at 10 ns resolution at a coastal station to minimize the propagation effects. The frequency spectrum of the electric field of positive return strokes were computed applying the Fourier transform technique in the range of 10 kHz to 20 MHz owing to the fact that this range of frequency is of very much interest to the researchers and design engineers. The amplitude of the energy spectral density decreases nearly as ƒ-1 from 10 kHz to about 0.1 MHz and drops nearly as ƒ-2 up to 8 MHz. Applying the wavelet transform technique, the same positive return strokes are found to radiate in the frequency range of 5.5 to 81 kHz with the average spread distribution of 13.6 kHz to about 30 kHz. From frequency spectrum obtained from the Fourier transform it is difficult to identify as which phase of the return stroke radiates in the higher frequency range and that in the lower frequency range, whereas, one can easily identify from the frequency spectrum obtained with the wavelet transform that ramp portion of the positive return stroke radiates in the larger spectral range as compared to that of initial peak of the return stroke. Also, from the spectral density map obtained from wavelet transform one can easily observe the contribution of each phase in a range of frequency, which is not possible from the Fourier transform technique. Clearly, the wavelet transform is much more powerful tool to extract the frequency domain information of a non-stationary signal as compared to that of Fourier transform. PubDate: 2021-02-15 DOI: 10.3126/sw.v14i14.34986 Issue No:Vol. 14, No. 14 (2021)
Authors:Prakash Kumar Jha, Vinay Kumar Jha Pages: 51 - 61 Abstract: The dry spinach leaves fine powder was modified by activation with conc. H2SO4 and the adsorbent material was then characterized by using FTIR, EDX, optical microscopy, XRD analysis and methylene blue adsorption method. The EDX result showed about 95 % carbon in the adsorbent material. The maximum specific surface area measured was 499 m2/g. The weak and broad XRD diffraction peaks at 2θ angles 20.5 and 42° were characterized as of activated carbon with the appearance of sharp peak of SiO2 at 2θ angle 26.37°. Optical microscopy Image analysis showed the Porous nature of adsorbents. The adsorption of arsenite on the modified spinach leaves powder adsorbent was investigated by varying different experimental parameters such as pH, adsorbent dose, contact time and As (Ⅲ) ion concentration. The adsorption process was found to be best fitted to Langmuir adsorption isotherm model controlled by pseudo-second–order kinetics with the rate constant value 0.01830 g/(mg·min). The maximum adsorption was observed at pH 6 at room temperature. The maximum adsorption capacity for As (Ⅲ) on modified spinach leaves powder was found to be 58.480 mg/g. The value of ∆G was -22 kJ/mole which confirmed the adsorption process was favored by physisorption. The slope of the linear plot of Qt vs t0.5 was linear but not passed through the origin, which indicates that, the intraparticle diffusion was not only rate controlling step. PubDate: 2021-02-15 DOI: 10.3126/sw.v14i14.34987 Issue No:Vol. 14, No. 14 (2021)
Authors:Suraj Neupane, Shriram Sharma, Puja Sharma Pages: 62 - 67 Abstract: In this frequency spectrum electric fields radiated by the unusual lightning activities have been computed using the wavelet transform technique. The unusual lightning activities have very recently been identified activities and are very poorly understood among the lightning community. As the electric fields are very recently identified and are measured in time domain, to the best of our knowledge, their frequency content has not been studied as of today. To understand the physics of the discharge mechanism of such events, the frequency domain information plays a significant role. In order to extract frequency domain information from the time domain electric field signatures the wavelet transform technique has been employed. For the purpose, the electric field pertinent to the unusual activity, has been divided into two parts namely main activity and the preceding opposite polarity field change. From the computation, it is found that the opposite-polarity field change radiates energy in the spectral range of 2 kHz to 173 kHz whereas, the main activity predominantly radiates in the frequency range 2 kHz to 162 kHz. Such a wider spectral range that the unusual activities radiate have not been reported for the other known activities such as positive and negative return strokes. Evidently, the unusual events have some unique origin of discharge unlike the known activities. Further, as the unusual events were noticed in the temperate region (Uppsala, Sweden) and Sub-tropical climatic zone (Kathmandu, Nepal), it should have some common source of origin between two regions. PubDate: 2021-02-15 DOI: 10.3126/sw.v14i14.34988 Issue No:Vol. 14, No. 14 (2021)
Authors:A. K. Gautam, B. Aryal Pages: 68 - 74 Abstract: A far infrared dust cavity nearby AGB star namely AGB19+26 found to be located, centered at R.A.(J2000)= 20h 02m 02.8s and Dec.(J2000)= 26° 52' 36.8".Distribution of Planck function, dust color temperature, dust mass and visual extinction of the far infrared cavity was studied. This cavity was found to have following properties: (a) it is located nearby AGB star named AGB19+26around far infrared loopG064-01 at 2000 pc, (b) it is close to the Galactic plane at galactic latitude -1.2° therefore the radiation field is strong and (c) the diameter of the cavity is greater than 0.2° on IRAS. The dust color temperatures are found to be in the range 21.48 ± 0.25 K to 22.03 ± 0.12 K. Planck function was found to be non-uniform along its extension and compression, suggesting that the dust and grains are not in the local thermodynamic equilibrium, possibly because of external cause. It is therefore, a deviation from the Gaussian distribution is noted in the histogram of dust color temperature. It is concluded that the cavity was formed due to the high pressure events occurred in the past. PubDate: 2021-02-15 DOI: 10.3126/sw.v14i14.34990 Issue No:Vol. 14, No. 14 (2021)
Authors:Sunita Shrestha, Anita Kumari Dhami, Armila Rajbhandari Nyachhyon Pages: 75 - 82 Abstract: The low cost adsorbents were prepared from raw rice husk (RRH) and NaOH treated rice husk (NRH). Then prepared materials were characterized by XRD, FTIR and surface area of rice husk adsorbent were determined by methylene blue adsorption method. XRD showed amorphous nature with low crystallinity of the material. The FTIR spectra showed the presence of oxygenated functional groups such as ester, phenol, carbonyl and silica on the material. The surface area of RRH and NRH were found to be 387 and 417 m2/g respectively. Thus, prepared adsorbents were used for the removal of Fe(II) ion from aqueous solution. The influence of various parameters like pH, adsorbent doge, and contact time were studied for the better adsorption of Fe(II) on rice husk adsorbents. Results revealed that the maximum efficiency was achieved at pH 3 for Fe(II). The adsorption process was found to be best fitted to Langmuir adsorption isotherm model controlled by pseudo-second–order kinetics with the rate constant value i.e. 0.0218 and 0.0235 g/(mg·min) for RRH and NRH respectively. The χ2 values of pseudo second order was found to be lower which confirmed chemisorption, involving ion exchange and valence forces through sharing or exchange of electrons between adsorbent and adsorbate. The maximum adsorption capacity for Fe(II) on RRH and NRH was found to be 2.9 mg/g and 5.6 mg/g respectively. The positive ∆G value represents the randomness of the system during adsorption process. The slope of the linear plot of Qt vs t0.5 was linear but not passed through the origin, which indicates that, the intraparticle diffusion was not only rate controlling step. Temkin value showed the maximum binding energy (KT) for NRH was 16.4 L/g and for RRH it was 12.2 L/g. PubDate: 2021-02-15 DOI: 10.3126/sw.v14i14.34991 Issue No:Vol. 14, No. 14 (2021)
Authors:Kranti Kumal, Deepak Raj Pant, Biva Aryal, Giri Raj Tripathi, Giri Prasad Joshi Pages: 83 - 89 Abstract: Mistletoes are being used for food or beverage and for variety of medicinal purposes. In Nepal, mistletoes are traditionally used as fodder and as remedy to cure various ailments. In this study, methnolic extracts of seven common mistletoe species (Helixanthera ligustrina, Macrosolen cochinchinensis, Scurrula elata, S. parasitica, Viscum album, V. articulatum and V. liquidambaricola) were analyzed for their phytochemical constituents and antioxidant potential. The total flavonoid content (TFC) and total phenol content (TPC) were quantitatively determined by aluminum chloride colorimetric and folin-cioalteau reagent methods, respectively. The TFC was found highest for V. album (31.5 ± 2.3 mg QE/g) and lowest for M. cochinchinensis (24.9 ± 2.3 mg QE/g). Similarly, highest total phenolic content was found in S. parasitica (32.9 ± 2.5 mg GAE/g) and lowest in V. album (20.6 ± 2.1 mg GAE/g). The antioxidant activity measured by DPPH radical scavenging assay was found best for S. parasitica (with lowest IC₅₀ value; 26.0 ± 0.7 µg/ml) among the studied mistletoes. Overall analysis provides scientific evidence in favor of indigenous use of these mistletoes as a source of fodder, food and for medicinal purposes PubDate: 2021-02-16 DOI: 10.3126/sw.v14i14.34999 Issue No:Vol. 14, No. 14 (2021)
Authors:Saroj Kafle, Ram Chandra Basnyat, Meena Rajbhandari Pages: 90 - 98 Abstract: Drymaria diandra is used in Nepalese traditional medicine to treat various ailments. The hexane, dichloromethane, ethyl acetate, methanol and 50% aqueous methanol extracts of D. diandra were prepared and screened for the presence of different classes of phytochemicals. Methanol and 50% aqueous methanol extracts showed the presence of phenolics, flavonoids and carbohydrates so their total contents were estimated. The highest amount of phenolics and flavonoids were found in methanol extract (190.58±2.21 mg GAE/g extract and 69.25±7.91 mg CE/g extract respectively). The highest amount of sugar was found in 50% methanol extract (185.60±2.53 mg GE/g extract). Similarly, the extracts were tested for the antibacterial activity against one gram negative bacteria, Escherichia coli and one gram positive bacteria Staphylococcus aureus. All the tested extracts showed good antibacterial activity against both bacteria with the inhibition zone ranging from 10 -22 mm. The free radical scavenging activity was determined using DPPH free radical. Both methanol and 50% aqueous methanol extracts showed strong antioxidant activity (IC50 13.61 and 16.94 μg/ml respectively). The GC-MS analysis of hexane extract revealed the presence of more than 22 compounds. However, 9 compounds were identified by comparing the mass fragmentation pattern of each compound with the standard NIST mass spectral database PubDate: 2021-02-16 DOI: 10.3126/sw.v14i14.35000 Issue No:Vol. 14, No. 14 (2021)
Authors:Mukul Pradhan, Madhumati Bajracharya, Manisha Rai, Piyush Man Shakya, Basudev KC, Bishnu Prasad Bhusal Pages: 99 - 105 Abstract: Signatures, as one of the behavioral human characteristics are generally recognized as legal means for verifying an individual's identity by administrative and financial institutions. A signature is developed by a person and it can change over time. Signatures are prone to influences by age, physical and mental conditions. In this study tremulous signatures including questioned and standards related to 50 real cases resolved by National Forensic Science Laboratory of Nepal were collected. The time interval between questioned and standard signatures was up to ten years. Sixteen major characteristics along with their forty-one sub characteristics of each case were studied. Among sixteen major characteristics in the tremulous signatures, study shows that the characteristics like the style of writing in hand printed form, pen pauses, medium pen pressure, poor line quality, pen lifts are most prominently observed. Tremors were absent mostly in the terminal strokes of letters. The letters written were varied in size and those were 6% small, 70% medium and 24% large. Interestingly no any retouch attempts were found to complete the shape of letters. PubDate: 2021-02-17 DOI: 10.3126/sw.v14i14.35020 Issue No:Vol. 14, No. 14 (2021)
Authors:Narayan Prasad Ghimire, Nita Adhikari, Ramesh Raj Pant, Sudeep Thakuri Pages: 106 - 114 Abstract: This study presents the geochemical composition and water quality of waters in the West-Seti and Tamor River basins in Nepal Himalaya with the aim to reveal their hydrochemical characteristics and to evaluate the water quality. Water samples were collected from 18 sites of the rivers in the pre-monsoon season and analysed the physicochemical parameters to characterize their quality. The parameters- temperature, pH, conductivity, and total dissolved solids were measured in the field, while the major ions (Na+, Ca2+, Mg2+, Si4+, SO42−, NO3−, HCO3−, Cl−, and F−) were analyzed in the laboratory. Overall results of physicochemical parameters revealed that the ionic strength is much distinct; however, the waters are chemically pure in both the river basins with very less electrical conductivity (<250 µS/cm) and total dissolved solids (<120 mg/L). Bicarbonate (HCO3−) has a significant correlation with Ca2+ and Mg2+ suggesting carbonate rock weathering as the dominant geochemical process in both of the basins. The concentrations of Ca2+, Mg2+, and HCO3− in the water of the West-Seti is relatively higher than the waters in the Tamor River basin. Mostly, the geochemical facies of both the rivers are characterized by the Ca-Mg-HCO3- type (88.9%), with dominant carbonate dominated lithology. However, hydrochemical facies clearly suggested spatial discrimination between two basins with dominant geogenic signatures as Ca-SO4-Cl type water facies are also reported from the Tamor River basin. The results exhibited that the concentrations of measured parameters were relatively very low and within the WHO guideline values and currently under a safe level of the water quality for drinking and ecosystem health perspectives; however, further in-depth research is recommended in the periodic basis to assess traces of climate change imprints, and anthropogenic interferences for more consistent and reliable dataset. The findings of this study could be useful for the water quality management in the glacier-fed Himalayan River basins. PubDate: 2021-02-17 DOI: 10.3126/sw.v14i14.35021 Issue No:Vol. 14, No. 14 (2021)
Authors:Sudarshana Shakya, Bindra Devi Shakya, Amrita Tamrakar, Bijaya Adhikari, Sabita Nepal, Pawan Raj Shakya Pages: 115 - 123 Abstract: Removal of heavy metals is very important in wastewater treatment process, due to their toxic effects on the environment. Biological treatment has attracted researchers for years since it has many advantages over physical and chemical methods for removing heavy metals from wastewater. The purpose of this research was to assess the biosorption of Cd2+ by wildtype (WT) and CdR-99 resistant line of Chlorella vulgaris confirming mechanisms of resistance to Cd2+ toxicity and the effect of the variable concentrations of Cd2+ on their growth. Exposure of both algal cell lines to increasing Cd2+ concentrations resulted in progressive inhibition of growth as revealed by growth experiments. The higher ID50 value (38 μM Cd2+) of CdR-99 resistant line exhibited some degree of resistance to Cd2+ toxicity. Metal content was determined by flame atomic absorption spectrometry (FAAS). When exposed to the growth medium containing 50 μM Cd2+, CdR-99 resistant isolate proved to be efficient cell line compared to the WT, in terms of adsorption and removal of Cd2+ at 15 min and 48 hr interval of time respectively. Extracellular Cd2+ adsorption was found significantly higher than intracellular uptake in both the tested cell lines. Total Cd2+ accumulation and distribution between the external and internal cell fractions of the CdR-99 were significantly higher to the WT. Thus, the CdR-99 cell line appeared more resistant to Cd2+ toxicity and hence may be used for wastewater treatment and remediation of metal contaminated sites. PubDate: 2021-02-17 DOI: 10.3126/sw.v14i14.35022 Issue No:Vol. 14, No. 14 (2021)
Authors:Khadka Bahadur Pal, Kiran Bishwakarma, Tarka Bahadur Chalaune, Durga Upadhaya, Tark Raj Joshi, Lal B Thapa, Motee Lal Sharma, Susan Joshi, Ramesh Raj Pant Pages: 124 - 131 Abstract: Freshwater contamination remains a challenging issue for the sustainable management of wetland ecosystems. This study aims to evaluate the water quality of Jhilmila Lake, Kanchanpur, Nepal by adopting standard test procedures, geochemical indices, and multivariate statistical analysis. The surface water samples were collected during the postmonsoon season in 2018 to assess the hydrochemical parameters such as pH, electrical conductivity (EC), total dissolved solids (TDS) and dissolved oxygen (DO), ammonium (NH4+ ), sodium (Na+), potassium (K+), calcium (Ca2+), magnesium (Mg2+), chloride (Cl-), sulphate (SO42-), nitrate (NO3-), phosphate (PO43-), bicarbonate (HCO3-) and total hardness (TH). The EC ranged from 162-190 µS/cm while TDS was 87-101 mg/L. The concentration of DO in the lake was in the range of 4.77-6.21 mg/L, indicated mild organic pollution. Moreover, the results revealed the moderate alkaline nature of water with the pattern of average ionic dominance of Ca2+>Na+>Mg2+ >K+>NH4+ for cations, and HCO3˗> Cl-> SO42- > NO3- > PO43- for anions. The principal component analysis demonstrated four major components indicating the association of EC, TDS, Ca2+, Mg2+, and HCO3- ; Na+ , PO43- and SO42-; NO3- and K+ ; and Cl- for PC1, PC2, PC3, and PC4, respectively exhibiting both the geogenic and anthropic origin. Overall, the Jhilmila Lake was less polluted, and all the measured water quality parameters were found within permissible limits in terms of drinking purposes. The findings of this study could help for the sustainable management of the lake by providing better insights into the water quality and hydrochemistry of the lake. PubDate: 2021-02-17 DOI: 10.3126/sw.v14i14.35023 Issue No:Vol. 14, No. 14 (2021)
Authors:Sushila Devi Shrestha, Anjana Devkota, Pramod Kumar Jha Pages: 132 - 140 Abstract: The urban air pollution is a major environmental concern, particularly in the developing countries and in their major cities. In the present study an attempt has been made to assess the air pollution effect on micromorphological and biochemical parameters of Callistemon citrinus and Lagerstroemia indica. Biochemical parameters were analyzed by using standard protocol. one-way analysis of variance was performed with SPSS software, v. 20.0, and Duncan test (p ≤ 0.05) was used to compare averages of all measured biochemical parameters and micromorpholgical features. There was a decrease in number of stomata of both species at highly polluted site compared to less polluted site (control). Stomatal index of both species was found to be reduced in polluted site when compared to control. The number of clogged stomata was less in control area samples when compared to polluted sample. A number of epidermal cells were significantly decreased at heavily polluted site. Total chlorophyll content and leaf extract pH in both the plants were found to be significantly higher in control sites than in heavily polluted sites. Ascorbic acid, relative water content, and Air Pollution Tolerance Index (ATPI) was found to be significantly higher at more polluted plants than at control. Based on the present study results, Callistemon citrinus emerged as the most tolerant species with the highest APTI. Hence, Callistemon citrinus can be suggested for plantations along the roadside of urban areas for green belt development. PubDate: 2021-02-17 DOI: 10.3126/sw.v14i14.35024 Issue No:Vol. 14, No. 14 (2021)
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