Authors:Prem Raj Dhungel, Sanat Kumar Sharma, Uday Raj Khanal Pages: 1 - 3 Abstract: Behaviour of the Dirac field in FLRW space is further investigated extending the previous work. WKB approximation up to the third order was used to solve the temporal part of the Dirac’s equation and hence the energy and particle current have been calculated to further details. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45632 Issue No:Vol. 15, No. 15 (2022)
Authors:Pushpa Nidhi Gautam, Buddhi Prasad Sapkota, Kedar Nath Uprety Pages: 4 - 9 Abstract: In this work both linear and nonlinear advection-diffusion equations are considered and discussed their analytical solutions with different initial and boundary conditions. The work of Ogata and Banks, Harleman and Rumer, Cleary and Adrian, Atul Kumar et al., Mojtabi and Deville are reviewed for linear advection-diffusion equations and for nonlinear, we have chosen the work of Sakai and Kimura. Some enthusiastic functions used in the articles, drawbacks and applications of the results are discussed. Reduction of the advection-diffusion equations into diffusion equations make the governing equation solvable by using integral transform method for analytical solution. For nonlinear advection-diffusion equations, the Cole-Hopf transformation is used to reduce into the diffusion equation. Different dispersion phenomena in atmosphere, surface and subsurface area are outlined. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45668 Issue No:Vol. 15, No. 15 (2022)
Authors:Krishna Subedi, Sujata Adhikari, Sabin Dhungana, Bhoj Raj Poudel, Megh Raj Pokhrel Pages: 10 - 17 Abstract: A simple and sensitive spectrophotometric method has been optimized for the determination of phosphate in the presence of arsenate. This method is based on the formation of phosphomolybdate complex from phosphate and added molybdate ion in an acidic medium, followed by the reduction of the complex with hydrazine hydrate. The system obeys Lambert-Beer’s law in the concentration range 60-1080 ppb. The optimized volume of different reagents was 3.5 mL of 0.25% ammonium molybdate, 1.5 mL of 0.25 N sulfuric acids, and 1 mL of 0.5 M of hydrazine hydrate. The time required for the full-color development was 15 minutes at 30oC. The arsenate interference was successfully removed by using sodium thiosulphate and sodium metabisulfite below the arsenic concentration of 100 ppb. 0.2 mL of 1 M sodium metabisulfite and 1 mL of 0.1 M sodium thiosulphate were found to be the optimum volume for inhibiting arsenate interference below 100 ppb arsenate concentration. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45636 Issue No:Vol. 15, No. 15 (2022)
Authors:Bhoj Raj Pant, Jitendra Upadhyaya Pages: 18 - 25 Abstract: Cross-linked carboxymethyl starch of different degrees of substitution-DS (DS, 0.14, and 0.49) was synthesized and investigated the effect of DS on cross-linking of starch derivatives. Native corn starch was first carboxymethylated in an alkaline condition of the alcoholic medium using sodium chloroacetate as a carboxymethylating agent. The aqueous Carboxy Methyl Starch (CMS) solutions (15 and 50%, w/w) were then irradiated by electron beam (EB) radiations at 1, 2, 3, 5, 10, 20, and 50 kGy dosages and underwent radiation cross-linking, resulting in a Cross-linked Carboxymethyl Starch (CCMS). The gel content to be estimated in the CCMS of different DS (0.14 and .049) with 50% (w/w) CMS was 1.3 and 19.2%. These are the maximum degrees of cross-link achieved with 50% (w/w) aqueous CMS irradiated at 5 and 2 kGy dosages. Our results showed that the cross-linking of CMS depends on the DS of carboxyl groups and the concentration of CMS. Maximum cross-linking observed with CMS of DS, 0.49, and 50% (w/w) concentration demonstrates that the increased DS and concentration of CMS are favorable for cross-linking of CMS. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45670 Issue No:Vol. 15, No. 15 (2022)
Authors:Sanoj Hajam, Hira Mani Trital, Armila Rajbhandari Nyachhyon Pages: 26 - 32 Abstract: Zinc oxide (ZnO) nano additives were successfully synthesized in laboratory by precipitation technique. The XRD showed crystalline nature of ZnO with the average crystallite size of 16 nm. The stretching band of ZnO was found at around 400 cm-1 to 600 cm-1 wave number in FTIR. The prepared nano particle have been used as nano additive and sodium lauryl sulphate (SLS) as surfactant, in base oil to improve physio-chemical parameter of lubricants. The result revealed that the additive blended base oil (lubricant) has shown excellent lubrication properties. The higher kinematic viscosity of 90.72 and 10.40 were obtained at 40oC and 100o C respectively. Similarly, viscosity index were found to be 96 which was improved indicating the use of lubricant in slightly high temperature is possible. The pour point was found to be decreased to -9.2oC which was quite significant and could be used in cold environment. The flash point was also found to be increased from 225o C to 230oC which indicated that the prepared nano additive ZnO acts as flash point enhancer. The corrosion test done by copper strip comparative method and was found to be 1b for additive indicating the non-corrosive nature. The absence of moisture and pH around the neutral range 6.65 showed that the additive blended lubricant is not harmful for machinery devices. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45643 Issue No:Vol. 15, No. 15 (2022)
Authors:Khaga Raj Sharma, Nav Raj Khanal Pages: 33 - 43 Abstract: The aim of this research is to collect Zingiber officinale from the different altitudes of Nepal for the study of antioxidant activity, quantification of phenolic and flavonoid content, α-amylase enzyme inhibition and the toxicity test. The phenolic and flavonoid content in methanol extracts of Z. officinale was estimated by Folin-Ciocalteu colorimetric method and aluminium chloride colorimetric assay. The antioxidant potential was determined by DPPH free radical scavenging assay and the toxicity of the extracts was performed by brine shrimp lethality assay. Similarly, the antidiabetic activity of extracts was evaluated by the α-amylase enzyme inhibition assay. The antioxidant potential of Zingiber officinale was evaluated as inhibitory concentration IC50 values which were found to be in the range from 44.43 µg/mL to 65.71 µg/mL in the sample collected from the different regions of Nepal. The total phenolic content in Z. officinale collected from different regions was found to be in a range from 118.19±3.32 mg GAE/g to 222.04±24.93 mg GAE/g. The total flavonoid content was found to be lower than that of total phenolic content in Z. officinale collected from different altitudes of Nepal. The total flavonoid was found to be in a range from 42.10 ± 4.48 mg QE/g to 62.95 ± 0.70 mg QE/g. The brine shrimp lethality LC50 in Z. officinale collected from the different regions was found to be higher than 1000 µg/mL. The α-amylase enzyme inhibition IC50 of Z. officinale growing in different regions of Nepal was found to be in a range from 161.25 µg/mL to 216.59 µg/mL. This study is the first attempt for comparing the antioxidant and α-amylase enzyme inhibition activity of Z. officinale growing at different altitudes of Nepal. PubDate: 2022-06-17 DOI: 10.3126/sw.v15i15.45885 Issue No:Vol. 15, No. 15 (2022)
Authors:Bimala Subba, Sanjay Gaire Pages: 44 - 50 Abstract: The plant kingdom is a wide field to search for natural effective antioxidant and oral hypoglycaemic agents that have slight or no side effects. The present study was carried out to analyze the phytochemical, antioxidant and anti-diabetic activities of six ethno-medical plants of Nepal viz Berberis aristata, Murraya koenigii, Xanthium strumarium, Cuscuta reflexa, Myrica esculenta and Syzygium cumini. Phytochemical screening of methanolic extract of all selected plants showed the presence of different chemical constituents such as alkaloids, polyphenols, flavonoids, terpenoids, saponins, glycosides and tanins. The antioxidant activity was evaluated by 2, 2-diphenyl-1-picryl hydrazyl (DPPH) free radical scavenging activity. Ascorbic acid was used as standard during DPPH assay. S. cumini and M. esculenta were seen most active with IC50 values 33.35 µg/mL, 35.19 µg/mL, respectively. The anti-diabetic activity was evaluated by using α-amylase inhibition method. Acarbose was used as positive control during the assay. X. strumarium, S. cumini, M. esculenta, B. aristata were found to be potent towards α-amylase inhibition with IC50 values 197.21 µg/mL, 206.22 µg/mL, 246.07 µg/mL, 270.04 µg/mL. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45645 Issue No:Vol. 15, No. 15 (2022)
Authors:Gagan Shrestha, Sabita Shrestha Pages: 51 - 57 Abstract: In this paper, we have reported the synthesis of CuO nanoparticles (CuO NPs) by cost effectively and environmental friendly method using the rhizome extract of Rubus ellipticusfor photocatalytic degradation of methylene blue. The biomolecules present in the extract acts as reducing agent and stabilizer for the synthesis of CuO NPs. The synthesized nanoparticles were characterized by using the different analytical instrument like UV-Visible spectrophotometer, XRD and FT-IR. The absorbance at 595 nm indicates the formation of CuO NPs which on annealing at 400°C for four hours oxidizes and forms CuO NPs which shows maximum absorbance at 265 nm. XRD analysis confirms the formation of crystalline structured nanoparticles without any impurity. So formed nanoparticles were found to be of size 4.8nm and 5.7 nm which was calculated by using Debye-Scherrer equation. The FTIR confirms the presence of various bioactive components, which acts as reducers and stabilizer. In addition, the photocatalytic degradation activity of the CuO NPs was studied for the degradation of the methylene blue in presence of sunlight. The catalytic activity was monitored using the UV-Visible spectrophotometer. It was found that the dye gradually degrade sunlight irradiation. This study highlights the application of CuO NPs for photocatalytic degradation of dye which can be extended for the waste water treatment. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45646 Issue No:Vol. 15, No. 15 (2022)
Authors:Kriti Paudel, Shradha Basi-Chipalu Pages: 58 - 64 Abstract: Drinking water quality assessment in Kathmandu valley has always been crucial with reference to public health importance. The objective of this study was to assess the quality of drinking water with respect to physiochemical and microbiological parameters. A total of 63 random water samples were collected from different sources like stone spout, tap, well, boring, hand pumps and jar from different wards of Kageshwori Manohara Municipality, Kathmandu. The study was carried out for 6 months from January to July, 2019. The pH of the samples was in the range of 6.5-7.2, temperature 5-19 °C, chloride 0-96.56 mg/L, nitrate 0-5.4 mg/L and iron 0-1.1 mg/L. The physicochemical parameters including pH, temperature, chloride, nitrate of the samples were found to lie within the WHO guideline value except iron where 4 (6.34%) samples including 2 tap, 1 boring and 1 well exceeded WHO guideline. The bacteriological analysis of water samples revealed the presence of total coliform in 35 (55.56%) out of 63 samples, among which 8 (12.69%) were found to have faecal coliform. Furthermore, Salmonella spp. was isolated from 1 out of 63 samples. However, all the samples were free of Shigella spp. and Vibrio spp. It was found that most of the water samples were non potable as total and faecal coliform exceeded the WHO guideline value of drinking water. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45647 Issue No:Vol. 15, No. 15 (2022)
Authors:Kanchan Prasad Adhikari, Kanchan Sarga Nyaichyai, Birendra Bahadur Chand, Hanson Khadka, Saroj Sharma, Tara Khanal Pages: 65 - 69 Abstract: One of the important goals of the use of X-rays is to diagnose a disease and its extent and minimizing the adverse effect. In diagnostic X-ray, there is an important issue concerning the quality of the image and the exposure of radiation to the patient. Regular practice of quality control in diagnostic X-ray is essential to provide good quality images, decrease hazard to patients, and enhance the appropriate diagnosis. Quality control tests were carried out at six fixed X-ray units at National Academy of Medical Sciences, Bir Hospital and National Trauma Center. Parameters like kVp accuracy, timer accuracy, Reproducibility of kV, time and dose, variable mA and radiation output Linearity with the acceptance limits were checked. Radiation leakage, spatial resolution, contrast resolution and field alignment tests were also carried out. Quality control tests of kVp dose, dose rate, HVL, mAs, beam alignment and leakage radiation shows mixed results. The measured values were within limit in four X-ray units. Until now we do not have any regulations in Nepal on acceptance testing of x-ray units after installation. The need for quality assurance of X-ray needs to be taken to avert detrimental effects to patients and staff. Institutes must introduce a mandatory system for acceptance tests of X-ray when installed and alongside regular quality control programs. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45648 Issue No:Vol. 15, No. 15 (2022)
Authors:Ganga Paudel, Bindu Dahal, Ramesh Raj Pant, Kiran Bishwakarma, Sanjeeb Sharma, Suman Man Shrestha, Motee Lal Sharma, Mahesh Prasad Awasthi Pages: 70 - 85 Abstract: Taudaha Lake is an important lake in central Nepal because of its cultural, aesthetic, ecological and economic values. The assessments of water quality and hydrochemical characteristics were carried out by collecting samples from 20 different sites of the lake in August 2021. Analysis of temperature, pH, electrical conductivity, total dissolved solids, turbidity, dissolved oxygen, total hardness, major cations (Ca2+, Mg2+, Na+, K+, Fe3+ and NH4+) and major anions (HCO3-, Cl-, NO3-, SO42- and PO43-) were carried out to assess the overall hydrochemistry of the lake. The obtained data were interpreted by using multivariate statistical techniques to explore pollution sources and characteristics of sampling points and compared with WHO and irrigation guidelines. Slightly alkaline water with less distinct spatial variation was found. The pattern of major ions is in order of Ca2+> Mg2+> Na+> K+> Fe3+> NH4+ and HCO3-> Cl-> SO42-> NO3-> PO43-. All parameters lie within the limit of WHO guidelines. Principal component analysis (PCA) provides four major components with 73.06% cumulative variance and hierarchical cluster analysis classifies five clusters. Results of PCA, CA, Piper, Gibbs, and mixing plots suggested that the hydrochemistry of the lake is primarily controlled by underlying carbonate-dominate lithology. Similarly, Wilcox diagram suggests that lake water is not severely affected by anthropic pollution and is suitable for irrigational purposes. It is recommended for further study on seasonal, and depth-wise water quality variations along with socio-ecological and ecotourism perspectives in the future. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45651 Issue No:Vol. 15, No. 15 (2022)
Authors:Hari Paudyal, Bimala Pangeni, Kedar Nath Ghimire, Katsutoshi Inoue Pages: 86 - 95 Abstract: Hydrated tri metal oxide (HTMO) precipitate is investigated using a mixed solution containing cerium, aluminum, and titanium by precipitation for fluoride ion removal from water.PZC for the investigated HTMO precipitate is determined to be 6.5 from pH drift method. Fluoride adsorption by HTMO precipitate is pH dependent, with adsorption rates of more than 98 percent occurring at pH 2.3 to 6.7. The highest solid phase distribution of fluoride is observed at pH around 6. Fluoride adsorption onto HTMO precipitate increased with temperature, implying that the adsorption reaction is endothermic, as evidenced by the positive value of ∆H⁰ calculated from the thermodynamic calculations. The spontaneous process is indicated by a negative ∆G⁰ value for alltemperatures. The fluoride adsorption rate onto this adsorbent is rapid, and equilibrium is reached in less than four hours. An alkali (NaOH) solution effectively desorbed fluoride from a fluoride-loaded HTMO precipitate. As a result, the HTMO precipitate studied in this work is expected to be a viable as fluoride-removing material from water. PubDate: 2022-06-16 DOI: 10.3126/sw.v15i15.45849 Issue No:Vol. 15, No. 15 (2022)
Authors:Saraswati Gaihre, Sujata Dhungel, Smrita Acharya, Samikshya Kandel, Naina Byanjankar, Tista Prasai Joshi Pages: 96 - 102 Abstract: This research was investigated to evaluate the quality assurance of water from different sources. All together 250 water samples (135 well water, 48 boring water, 50 treated water, and 17 tap water) were received from different parts of Nepal from December 2019 to April 2020. The physicochemical parameters of water samples were performed according to the standard methods for the examination of water and wastewater. The membrane filtration technique was applied for the determination of Total Coliform bacteria. The measurements of water quality parameters were compared with the upper and lower limits of the National Drinking Water Quality Standards (NDWQS), 2005. Out of 135 well water samples, pH (1.48%), conductivity (2.22%), turbidity (42.96%), total hardness (4.44%), iron (54.07%), ammonia (48.88%), and nitrate (2.22%) elevated values compared to National Drinking Water Quality Standards, 2005. Likewise, 2.08%, 6.25%, 64.58%, 4.1%, 47.91%, and 58.33% of boring water samples showed higher values than the National Drinking Water Quality Standards for pH, conductivity, turbidity, total hardness, iron, ammonia, respectively. Conductivity, total hardness, chloride, and iron were found below the standards for both treated and tap water samples. Arsenic concentration was found within the standard for all water samples while 0.74% of well water samples showed a higher concentration of chloride compared to the standard. Results revealed that the minimum and maximum concentrations of some parameters were found to vary among the water sources. Among the total water samples, 94.8% well water, 76.4% tap water, 56.0% treated water, and 14.6% boring water samples showed the presence of coliform bacteria. This concludes that most of the water sources were polluted with fecal contamination and without proper purification may lead to the risk of waterborne diseases. Therefore, systematic and regular monitoring of water sources should be implemented to maintain water quality. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45656 Issue No:Vol. 15, No. 15 (2022)
Authors:Prabin Dawadi, Gopiram Syangtan, Mohammad Ataullah Siddiqui, Bhupendra Lama, Kaushal Nepal, Dev Raj Joshi, Lok Ranjan Bhatt Pages: 103 - 112 Abstract: Cannabis seeds have been recognized as one of the most nutritionally complete food sources which are also used for medicinal as well as recreational purposes. In the present study, nutritional, phytochemical, antioxidant and antimicrobial properties of seeds of Cannabis sativa and Cannabis indica, collected from Makawanpur district, central Nepal were evaluated. Nutritional and phytochemical analysis was mainly based on the Association of Official Analytical Chemists (AOAC) methods, while antibacterial activity was tested using the agar well diffusion method. The results revealed that Cannabis seeds contain considerable amount of protein (32.08% to 43.04%), fat (30.86% to 42.40%), carbohydrate (8.39% to 13.79%), total phenolics (701.05 mg/100g to 1312.72 mg/100g), and total flavonoids (366.29 mg/100g to 385.12 mg/100g). The radical scavenging activity of the seeds ranges from 37.83% to 54.84% at the concentration of 6.25 µg/mL. The results indicate that both the species hold high and substantial antioxidant activities. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45657 Issue No:Vol. 15, No. 15 (2022)
Authors:Sarita Bhatt , Radha Krishna Joshi , Tika Ram Lamichhane, Madhav Prasad Ghimire Pages: 113 - 119 Abstract: This paper aims to integrate novel coronavirus daily cases in SAARC countries; India, Pakistan, Bangladesh, Nepal, Sri Lanka, Afghanistan, Maldives and Bhutan to forecast the epidemic trend of COVID-19 by using logistic model. The recent trend of coronavirus cases were analyzed from the COVID-19 epidemiological data for SAARC countries from 23 January 2020 to 31 May 2021. The final size, growth rate parameter and point of inflection of COVID-19 for each countries were calculated by fitting the logistic curve with the cumulative cases. The graphical patterns of COVID-19 daily cases reflect that its second wave impact is more devastating than the first wave in SAARC countries. The increasing trend of COVID-19 cases in these countries was well described by logistic model with coefficient of determination greater than 0.96. The predictive final size of the second wave infections is maximum for India which is 19.8 million with growth rate parameter of 0.08 and inflection time of 68 days whereas the predictive final size is minimum for Afghanistan which is 0.041 million with growth rate parameter of 0.06 and inflection time of 71 days. The logistic model is helpful in predicting the trajectory of the infected cases in a country if the current scenario of this type of infectious disease remains same. Also, it helps the government to frame policy decisions and necessary actions that controls the transmission of COVID-19 in the South Asian region. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45669 Issue No:Vol. 15, No. 15 (2022)
Authors:Anjana Devkota, Ritu K. Das Pages: 120 - 126 Abstract: Antimicrobial activity of invasive alien plant species Ageratina adenophora (Sprengel) R. King & H. Robinson was evaluated against six human pathogenic bacteria. The aqueous (distilled water) and alcoholic (methanol) crude extracts from the leaves of the plant were tested against three gram negative bacteria: Escherichia coli (ATCC 25922), Klebsiella pneumoniaea (ATCC 15380) and Proteus mirabilis (ATCC 49132) and three gram positive bacteria: Enterococcus faecalis (ATCC29212) Bacillus subtilis (ATCC6633) and Staphylococcus aureus (ATCC 25923) using disc diffusion method. Different concentrations of plant extracts (5, 10, 15, 20 and 25%) were applied and diameter of zone of inhibition (ZOI) of bacterial growth were recorded. Plant extract in both solvent exhibited pronounced results against tested bacteria. Methanolic extract of plant exhibited good activity against tested bacteria when compared with aqueous extract. The zone of inhibition of bacterial growth increased with increasing concentrations. Phytochemical screening of plant exhibited alkaloids, saponin, tannin and flavonoids and plant sample contains higher amount of alkaloid. The demonstration of activity against all tested organisms had shown that Ageratina adenophora can be used to produce raw materials/substances for further development of diverse antibiotics with broad spectrum of activity. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45660 Issue No:Vol. 15, No. 15 (2022)
Authors:Sony Bajracharya, Pawan Raj Shakya, Raihan Shrestha, Nishana Shrestha, Hrejon Tiwari, Ajay Jha, Achut Ram Pradhananga , Prem Kumar Shrestha Pages: 127 - 136 Abstract: Total 79 water samples were collected from dug wells located in five different municipal wards of Lalitpur Metropolitan City for assessment of water quality during pre-monsoon season. Physico-chemical parameters (temperature, turbidity, electrical conductivity (EC), pH, total hardness (TH), total alkalinity (TA), chloride, nitrate, ammonia and iron) and microbiological parameters (total coliform and protozoan parasites) were determined using standard protocols. The range and mean concentrations of the selected parameters in the water samples were found to vary among the selected wards under investigation. The physico-chemical parameters were compared with National Drinking Water Quality Standard (NDWQS) of Nepal and WHO standards. Parameters like pH, chloride, nitrate and iron were found within the permissible limits of NDWQS and WHO guidelines whereas parameter such as ammonia exceeded the maximum permissible limits. Turbidity, EC and TH however showed variable levels within NDWQS and WHO standards. Total coliform count showed only 4 (5.1%) of the total water samples were risk free whereas 43 (54.4%) samples demonstrated maximum microbial contamination and high risk level. Three types of protozoan parasites viz., Cyclospora, Cryptosporidium and Giardia were detected in the water samples. Among the five municipal wards, W. No. 16 has the highest percentage (66.7%) of total coliform contamination in dug wells. Pearson’s correlation analysis was also performed to understand the relationships among the selected water quality parameters. Presence of total coliform and protozoan parasites and exceeding the maximum permissible limits by some physicochemical parameters shows the water quality of dug wells of Lalitpur Metropolitan City is not satisfactory. But, the quality can be improved by effective treatment technologies, planning and policies, strategies and management practices. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45661 Issue No:Vol. 15, No. 15 (2022)
Authors:Prithivi Raj Joshi, Akkal Dhami, Bhawani Datt Joshi Pages: 137 - 144 Abstract: Natural background radiation level within Darchula district of Nepal was measured using a simple portable Geiger-Müller counter. Data were collected along six different directions at different places (three-five places) of the sample sites of the district and was averaged. The average data value with their standard deviation was used for analysis. In this study, the maximum radiation counts of 51.16 2.30 CPM were reported at Satan and the minimum counts of 25.96 2.30 CPM at Gokuleshwar. The observed radiation level of the Darchula district shows that the district is below the radiation risk level (nearly 100 CPM). PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45664 Issue No:Vol. 15, No. 15 (2022)
Authors:Jasana Maharjan, Vinay Kumar Jha Pages: 145 - 157 Abstract: Present study deals with the preparation of activated carbons from banana peels. The banana peels were subjected to pyrolysis at 700 ℃ for 1 hour in open air (O2-BP), nitrogen gas (N2-BP) and mixture of nitrogen gas and water steam generated to 60-70 ℃ (N2+H2O-BP). The raw and activated carbons from banana peels were characterized by XRD, FTIR and methylene blue adsorption methods.The N2+H2O-BP was used for the adsorption of As (III) ions from aqueous solution. Various parameters affecting the adsorption process like pH (4 to 10), contact time and initial metal ion concentration were varied during the adsorption process. The optimum pH for As (III) adsorption was at 7. An equilibrium time of 2 hours was required for adsorption of As (III) ion. The adsorption isotherms were determined by using Langmuir and Freundlich isotherms and the experimental data were better fitted to Langmuir equation with high coefficient of determination value (R2 = 0.9934). The experimental data fitted well to pseudo second order kinetic model with rate constant value of 0.0111 g/ (mg˖min). The adsorption of As (III) on banana peels was spontaneous and followed physiosorption mechanism. The value of separation parameters (RL) was found to be 0 < RL > 1 for all initial As(III) ion concentrations showed good adsorption of As(III) into banana peels. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45665 Issue No:Vol. 15, No. 15 (2022)
Authors:Shriram Sharma, Prabidhi Shrestha, Pitambar Shrestha Pages: 158 - 166 Abstract: Lightning is an extremely complex electrical discharge that occurs within the earth’s atmosphere. It is the biggest threat to communication and transmission towers and damages electronic and electrical equipment beyond repair directly or indirectly. Although the protection against the lightning hazards can be achieved with the available technology and knowledge, such measures are largely overlooked in the developing countries in particular. Protecting communication & transmission towers, communication & transmission systems from the direct lightning strikes and saving human lives, livestock and other property damages from indirect lightning is a big challenge to the service providers. Nepal is a lightning prone country where the communication towers and system are often the victims of lightning strikes. In this study, we have made field assessment at the various sites of Nepal Telecom’s Base Transceiver Station (BTS) and Repeater towers for investigating their status pertinent to lightning threat and protective measures adopted in those sites. The main objectives of the field assessment were to investigate the effectiveness of the protective measures adopted, identify their inadequacies and hence to provide appropriate solutions as per the international standards (IEC 62305-4), in order to improve the quality of telecom services. The lightning strikes to the towers inside the Kathmandu valley were recorded to be rare, however it was common in the outskirts. Although, severe damage to the towers were not observed neither were recorded, the status of the towers in the perspective of lightning hazards were not found to be in the sound state. Contact resistance of the earthing system, installation of SPDs and equipotential bonding of the system need to be improved. Further, the protective measures against the hazards due to indirect effects of lightning strikes were found to be extremely poor. We recommend the improvements in protective measures against lightning in the neighborhood of the towers for the human as well as equipment safety. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45666 Issue No:Vol. 15, No. 15 (2022)
Authors:Janak Ratna Malla, Walter Saurer, Binil Aryal Pages: 167 - 171 Abstract: This paper presents the search for substructures within the Supercluster S [227+006+0078]. To use the spectroscopic database (7th data release) of galaxies, studied the number density, all-sky distribution, and redshift maps to identify substructures based on their richness and compactness. And also to find out the substructures within the Supercluster, using the contour plot of number densities of galaxies within the appropriate radius values and number of nearby galaxies. PubDate: 2022-06-14 DOI: 10.3126/sw.v15i15.45667 Issue No:Vol. 15, No. 15 (2022)
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