Browsing by Author "Khanal, Lekha Nath"
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Item “Chemical Analysis and Biological Activities of Crude Extracts and Green Synthesized Silver Nanoparticles of Medicinal Plants from Mustang and Kaski Districts of Nepal(Institute of Science & Technology, 2023-06) Khanal, Lekha NathMedicinal plants contain numerous secondary metabolites with significant biological activities. Due to diverse geographical and climatic conditions, several indigenous plants that comprise unique phytochemicals having a wide spectrum of biological assets are found in Nepal. This study aims to synthesize, characterize, and evaluate the biological activities of silver nanoparticles (AgNPs) by using some of the active medicinal plants of the study area. Methanol extracts of the selected plants were evaluated for antioxidant, antibacterial and α-amylase inhibition activities by using the DPPH radical scavenging, agar well diffusion, and CNPG3 methods respectively. The chemical profiling of essential oil isolated from the aerial parts of Ephedra pachyclada and Ayenia grandifolia was performed by the GC-MS analysis. This study exposed the phytochemical and biological activities of methanol extract, chemical profiling of essential oil, and green synthesis of AgNPs by using an aqueous extract of A. grandifolia for the first time. Among the 22 plants evaluated, Rubus ellipticus, E. pachyclada, Pyrus pashia, Drynaria coronans, Mimosa rubicaulis, and Ziziphus mauritiana extracts exhibited significant antioxidant properties with the highest activity of A. grandifolia (IC50 = 12.87 ± 0.14 µg/mL). The GC-MS analysis of the essential oil (EO) of stem barks of A. grandifolia contained di-n- octyl phthalate (28.39%), 2,6,11 trimethyl dodecane (15.77%), 4,6 dimethyl dodecane (12.79%), and o-guaiacol (7.07%). The methanol extracts of R. ellipticus and P. pashia exhibited the highest antibacterial activity. The resazurin microtiter assay method revealed the MIC and MBC of the methanol root extract of R. ellipticus as 3.12 and 12.5 mg/mL respectively against Staphylococcus aureus ATCC 25923. The methanol stem bark extract of P. pashia exhibited the highest α-amylase inhibition activity with an IC50 value of 24.22 ± 0.10 µg/mL. From the preliminary investigation, A. grandifolia, R. ellipticus, P. pashia, and Z. mauritiana which exhibited the highest biological activities were used for the fabrication of AgNPs. Each of the plant extracts and AgNO3 (1 mM) in the ratio of 1:9 by volume were mixed with constant stirring at lab temperature (25 ± 2ºC), and neutral pH with constant stirring over a magnetic stirrer. The change of color into light brown within an hour was considered a visual indication of the growth of AgNPs which was further confirmed by the appearance of sharp SPR peaks in the UV-visible spectra. The UV-visible spectra at different reaction conditions of temperature, pH, and concentration were used to optimize the fabrication of AgNPs. FTIR spectra of the extract and the AgNPs were examined to detect the functional groups responsible for the reduction, capping, and stabilizing of AgNPs. The face-centered crystalline nature of the silver nanoparticles was established by the X-ray diffraction patterns by matching the diffractogram with the Joint Committee on Powder Diffraction Standards (JCPDS file no: 03-0921). It was further confirmed by the selected area electron diffraction (SAED) pattern having four discrete rings corresponding to the crystal planes at 110, 200, 220, and 311. The energy dispersive X-ray (EDX) analysis showed the presence of silver in the highest proportions and trace quantities of oxygen, chlorine, calcium, and carbon in the AgNPs. The surface morphology and nearly spherical shapes were determined by field emission scanning electron microscopy (FESEM) images. Transmission electron microscopy (TEM) was used to confirm the topographical, compositional, and morphological status of the AgNPs. Further, TEM images were used to find the sizes of the synthesized AgNPs which ranged from 28.05 ± 11.8 nm of A. grandifolia extract-mediated AgNPs to 16.73 ± 4.94 nm of Z. mauritiana extract-mediated AgNPs. The antioxidant activities of AgNPs synthesized by using Z. mauritiana (with an IC50 value of 37.02 ± 1.0 µg/mL) and A. grandifolia (with an IC50 value of 142.77 ± 10.75 µg/mL) were found to be nearly twice as potent as their respective crude extracts. The AgNPs synthesized using A. grandifolia demonstrated notable antibacterial activity, whereas its crude extract showed no such activity. The process of transforming plant material into AgNPs not only enhanced their antioxidant and antibacterial properties but also indicated the potential biomedical applications of these plant-based nanoparticles. Further investigation involving the synthesis of controlled-sized AgNPs from other plants, toxicity testing, and exploring potential applications would greatly benefit humanity.Item Chemical analysis and biological activities of crude extracts and green synthesized silver nanoparticles of medicinal plants from Mustang and Kaski districts of Nepal(Institute of Science and Technology, Chemistry, 2023) Khanal, Lekha NathAvailable with full textItem Professional Development Opportunities and Obstacles to Primary Level English Language Teachers(Faculty of English, 2015) Khanal, Lekha NathThis study seeks to identify the Professional Development Opportunities and Obstacles to Primary Level English Language Teachers of Institutional Schools in Bharatpur Municipality of Chitwan District. The researcher, therefore, applied a questionnaire, which was filled by forty primary level English teachers who were selected by random sampling method, Similarly ten principals of different school were selected by non-random purposive method to elicit data/information. A set of questionnaire and a structured interview schedule were the tools of data collection. After the analysis and interpretation of the raw data it was found that there is high opportunity for the professional development as the teacher get any facility at their schools. It is further found that they have good English environment, good library with many books, cognitive environment and communicative and good administration for their professional development. It was also found that lack of high qualitative training program as per need unbearable heavy teaching load, lack of promotion, less remuneration, negative attitude of teachers are the major obstacles to professional development. Most participants agreed that the sudden and rare visits of supervisors are the greatest institutional professional development obstacles. They agreed that money and financial issues are the main self-directed professional development obstacles. Majority also believed the unbearable heavy teaching load, lack of time, overcrowded classes, and absence of promotion are the most important professional development obstacles from the nature of the work. Likewise, from the interviews, there were no differences in interviewees' responses due to gender or academic qualification variables, but there were differences due to experience and age. This study has been divided into five chapters. The first chapter deals with the introduction general background, statement of the problem, rational of the study, objectives of the study, research question, significance of the study, delimitation of the study and operational definition of the key terms. The VII second chapter deals with the review of related literature and conceptual framework included for the study under which review of related literature, implications of the review for the study and theoretical and conceptual framework. Chapter three consists of methods and procedures of the study adopted for the study under which design of the study, areas of the study, sampling procedures, tools for data collection, data collection procedure, data analysis and interpretation procedure. Chapter four deals with result and discussion, concrete thing of the thesis which has been included results, interpretation of data, opportunities and obstacles to primary level English language and. Lastly, chapter five deals with conclusion and implications of the thesis which has been included summary of the findings, conclusion and implications.