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Browsing Physics by browse.metadata.otherinstitutetitle "Amrit Campus"
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Item ADSORPTION BEHAVIOUR OF NITRIC OXIDE MOLECULES OVER Ni, Pd, AND Pt-EMBEDDED GRAPHITIC CARBON NITRIDE(Amrit Campus, 2023-08-17) Poudel, Guna NidhiNitric Oxide adsorption on Ni, Pt, and Pd-Embedded graphitic carbon nitride has been studied com putationally using density functional theory. PAW pseudopotential with PBE exchange-correlation functional in GGA approximation was used for the relax, SCF, electronics, and magnetic calcula tions. Kinetic energy cutoff 550 eV was set up for plane wave basis set with ‘Gaussian’ type smear ing and width 0.05 eV. After relaxing, we get adsorbed energy of NO-GCN, NO-Ni-GCN, NO Pd-GCN and NO-Pt-GCN are −1.68 eV, −8.63 eV ,−6.61 eV, and −8.74 eV respectively. When functional transitional metals are embedded in GCN by adsorption of NO to its surface the results show that new energy states are introduced near the Fermi surface and modify the electronic prop erties of the system and the structure becomes a wrinkle. It means the conductivity of the system is considerably increased. Fermi energy of the GCN, NO adsorbs on GCN, NO adsorbs on Ni, Pd, Pt Embedded GCN are −1.72 eV, −1.36 eV, −0.65 eV, −0.64 eV, and −0.61 eV respectively. The band gap of the GCN, NO adsorbs on GCN, NO adsorbs on Ni, Pd, Pt-Embedded GCN are 1.3 eV, 1.12 eV, 0.98 eV, 0.45 eV and 0.32 eV respectively. During the adsorption process, electrons are transferred from the TM-Embedded GCN to NO molecules, due to metal the charge transfer from d orbitals to the NO gas. So the bond length of NO in TM-Embedded GCN increases. The magnetic moment of these compounds is 0 µB except NO-Pt-GCN compound which has obtained 0.98 µB due to the dxy and dyz orbital of the Pt atom. The magnetic moment of Ni-GCN and Pd-GCN is found to be 0 µB.Item COMPUTATIONAL STUDY OF HYDROGEN BONDED COMPLEX OF ETHANOL AND WATER USING VARIOUS FUNCTIONALS ON THE BASIS OF DENSITY FUNCTIONAL THEORY(Amrit Campus, 2023-08-17) Pudasaini, AnilComputational study of hydrogen bonded complex of ethanol and water using various functionals on the basis of density functional theory has been carried out using 6- 311++G(d,p), 6-311++G(2d,2p), and aug-cc-pVTZ basis sets. We have calculated binding energy, zero point vibrational energy, distance of the bond formed in the complex, bond angle after complex formation, frequency shift, electron density, and laplacian of electron density for the ethanol and water complex. The binding energy of the complex was found to be in the range of -4.258 kcal/mole to -6.232 kcal/mole . We have calculated the zero-point vibrational energy of the complex and found to be in the range of 1.54 kcal/mole to 1.85 kcal/mole . We have found the distance of bond formation in the complex in the range of 1.907 ˚A to 2.103 ˚A, the bond angle in the range of 172.73◦ to 178.80◦ , and frequency shift in the range of -151.76 cm−1 to -85.99 cm−1 . The electron density(ρ) and laplacian of electron density(∇2ρ) at bond critical points for the C2H5OH...H2O complexes are analyzed in DFT, and different levels of approximation by using AIM All software.Item EFFECT OF GLIDING ARC DISCHARGE PLASMA ON GERMINATION AND PRODUCTION OF OYSTER MUSHROOM (Pleurotus ostreatus)(Amrit Campus, 2023-08-17) Niure, DeepakAn experiment was conducted at plasma lab of the Central Department of Physics, Tribhuvan Univer sity, Kirtipur Kathmandu Nepal to study the effect of cold plasma on the germination and production of oyster mushrooms (Pleurotus ostreatus) by gliding arc discharge. The treatment includes four dif ferent methods for 10 samples on two replicate. Control, spawn treated with plasma, plasma activated water used for spraying and substrates treated with plasma. The main parameters measured during the experiment were the colonization and fruit appearance periods, the length and diameter of the stem and cap (pileus) diameters; the fresh weight of the first and second harvests of mushrooms, and the biological efficiency of various treatment methods. Among the different treatments of plasma, the time for colonization and fruit appearance was found to be faster than control. The length of stem was highest for spawn treated with plasma for three minutes, but the diameter of the stem was found to be the highest for treatment four minutes plasma treated water used and the diameter of cap found most significantly highest for spawn treated with plasma for three minutes. Similarly, the production and biological efficiency were found to be significantly highest in the case of spawn treated with plasma for two minutes, followed by substrates treated for ten minutes with plasma , and eight minutes of plasma activated water used respectively. Plasma treatment on oyster mushroom can play a significant role in the growth and production of mushrooms.Item PERFORMANCE ANALYSIS OF MICROSTRIP ANTENNAS FOR DIFFERENT MATERIALS(Amrit Campus, 2023-08-17) Simkhada, RameshThe Micro-strip antennas are widely used due to its compactness, simple manufacturing process, budget friendly and versatility. Here, carbon, abundant and easily available element is utilized in the process for the design and fabrication of antenna patch. Seeds of lapsi (Choerospondias axillaris), the indigenous plant of Nepal is used to extract carbon. The seeds are powered and activated chemically. The presence of carbon is verified using XRD technique. Resistance of dry powdered activated carbon is in the range Mega-ohm (MΩ) but after the coating of the paste of activated carbon in a polycarbonate substrate and acted by a laser of light-scribe drive various light and dark patterns were. The darker patches were found to be conducting and lighter patches were found to be non-conducting. After the activation by laser in activated carbon in a polycarbonate substrate resistance hugely dropped from Mega ohm (MΩ) to the range of Kilo-ohm (KΩ). For simulation part, High Frequency Structural Simulator (HFSS) software was used. First the basic rectangular antenna is designed and its properties were studied. Fractal swastika shape slot was later introduced in the design. The performance of antenna is optimized using the genetic algorithm. The optimized copper patch antenna with copper as ground in a polycarbonate substrate with no slot resonates at a frequency of 13.80 GHz with VSWR 1.34 and S11 parameter as -22.24 dB. On changing the patch as graphite in firstly mentioned identical conditions, antenna resonates at dual frequency of 15.40 GHz and 17.40 GHz with S11 parameters of -22.04 dB and -20.97 dB resp., VSWR of 1.17 and 1.19 resp. After the introduction of slot in copper patch antenna, multiple resonating frequencies were obtained as 9.0000, 13.8000, 15.0000, 17.4000 and 18.20000 GHz. In Graphite patch antenna also, there were multiple resonating frequencies. In comparison to cooper patch, graphite patch antennas showed better performance. After the introduction of swastika slot also, polycarbonate substrate has shown better performance for copper-copper patch-ground as antenna whereas properties were comparable in polycarbonate and corning glass substrate for graphite-copper as patch-ground antenna.Item STUDY OF DUST PROPERTIES AROUND HELIX NEBULA(NGC–7293) USING IRIS, AKARI, WISE SURVEYS, AND 2-DUST MODEL(Amrit Campus, 2023-08-17) Paudel, RajuThe present study aims to investigate the properties of the dust around Helix Nebula (NGC 7293) using IRIS, AKARI, and WISE surveys and the 2-Dust model. Helix Nebula is one of the well-known planetary nebulae in our Milky Way Galaxy. The study objectives include examining the dust color temperature, dust mass distribution, distribution of flux, and Jean’s criteria of the nebula, producing dust color temperature and dust mass maps of the field, and determining the mass loss rate, luminosity, inner shell radius, outer shell radius, and other dust properties of Helix Nebula using a density distribution function and comparing them to another model. The methodology employed includes using 2-Dust code, Aladin v10.0, and Python 3.7. The FITS image was taken from Sky View Virtual Observatory. The study findings indicate that the relative flux density is maximum around the central region and minimum around the outer region at F100 𝜇m and F22 𝜇m FITS images. The dust particle that emits a flux of 140 𝜇m is minimum in the central region. The dust color temperature of Helix Nebula varies depending on the survey used, with an average dust color temperature of (28.930 ± 0.005) K for the IRIS survey, (24.440 ± 0.078) K for the AKARI survey, and (277.490 ± 0.001) K for the WISE survey. The study also found that the dust color temperature was higher in the WISE survey than in the IRIS and AKARI surveys, suggesting an inverse relationship between the dust color temperature and the wavelength. The dust mass value was found to be higher in the AKARI survey and lower in the WISE survey. The calculated dust mass of Helix nebula using IRIS, AKARI, and WISE survey was found to be 0.10 M⊙, 0.56 M⊙, and 0.034 M⊙ respectively. The estimated dust mass in the circumstellar shell was 0.051 M⊙ and the mass loss rate was found to be 1.04×10−5 M⊙ yr−1 using the axisymmetric model. The study concludes that the results obtained from the 2- Dust code as well as the IRIS, AKARI, and WISE surveys provide a better understanding of the properties of dust around Helix Nebula.Item STUDY ON ELECTRICAL AND OPTICAL PROPERTIES OF ZINC OXIDE SEMICONDUCTOR FOR GAS SENSOR APPLICATION(Amrit Campus, 2023-08-17) CHAUDHARY, DINESH KUMARAmmonia, ethanol, acetone, etc. are commonly found as toxic gases in most places. The real-time monitoring of these gases is essential because their excessive exposure may produce serious health problems. In recent times, several metal oxide semiconductors (MOS) have been exploited for gas detection. In this context, zinc oxide (ZnO) is considered one of the potential materials for its interesting properties such as non-toxicity, high thermal & chemical stability, and easy tunable electrical & optical behavior. High working temperature (>300 °C ), poor selectivity, and low sensitivity are some of its shortcomings. The operation at high temperatures degrades the sensor’s stability and consumes power. This study aims to enhance the sensing characteristics of ZnO-based sensors after utilizing strategies like metal and metal-metal doping into it. Herein, the ZnO and metal-doped films were prepared by using spin coating, spray pyrolysis, and doctor blade methods for an in-depth understanding of gas sensing. Its optical and structural characterizations were done by ultra violet visible (UV-Vis) spectrophotometer and X-ray diffraction (XRD) respectively. Surface morphology and elemental composition were studied using scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis. The gas sensing performances of ZnO-based sensors were measured using a homemade gas sensor setup. At first, spin-coated ZnO was tested for the detection of traces of ammonia, ethanol, acetone, methanol, and isopropanol at room temperature. Its XRD and SEM micrographs demonstrated the polycrystalline wurtzite phase with a grainy surface. The band gap was found to be 3.202 ± 0.023 eV. The sensitivity measurements revealed the highest response of 38.5 ± 0.6 with an exposure of 400 ppm of ammonia vapour, indicating its selectivity among the tested gases. The results of sensitivity measurements over multiple cycles showed the device’s good stability. The sensing capability here was found to be better than other similar works. Hence, the results obtained here will be helpful in the development of a low-cost, effective room temperature MOS gas sensor with a lower detection limit of 20 ppm which is below the Occupational Safety and Health Administration’s (OSHA) approved threshold. For acetone sensing, ZnO deposited on an fluorine doped tin oxide (FTO) substrate prepared by doctor blade was used. XRD and fourier transform infrared (FTIR) spectroscopy were used for phase purity and optical characterization of ZnO nanoparticles (ZnONPs) prepared from the co-precipitation method prior to deposit on the FTO substrate. The sensing measurements demonstrated the maximum value of gas response of 25.697 ± 0.012 at an operating temperature of 285 ± 7 °C for exposure of 800 ppm of acetone along with the rapid response and recovery. This operating temperature was found to be lower than the published values that were prepared by different methods. The response & recovery times were measured to be 39 sec and 79 sec, respectively. Sequentially, in other sets of experiments, the undoped ZnO, Fe-doped ZnO (Fe-ZnO), and Sn-doped ZnO (Sn-ZnO) films were used to detect ethanol vapours in the temperature range of 100-300 °C. The sensitivity measurements for 2% Fe-ZnO film showed the highest response of 40.91 ± 0.23 at the exposure of 400 ppm of ethanol at 260 ± 7 °C. The comparison with similar reported values confirmed its goodness. And 2% Sn-ZnO film showed the highest response of only 17.659 ± 0.011 for 400 ppm exposure at 220 ± 5 °C. This working temperature was found to be slightly lower than the published value. Interestingly, this also reports that 2% Sn-ZnO film was able to detect as small as 0.5 ppm of ethanol. The spin-coated Fe-Al co-doped ZnO sensors were also tested to monitor ethanol in the temperature range of 120 − 360 °C. The 1%Fe-1%Al-ZnO sample showed a very high value of the response, 152.304 ± 0.003 at the exposure of 400 ppm at 290 ± 7 °C. It is due to an increase in specific surface area which occurs due to the reduction of grain size after Fe-Al co-doping. The observed values of response and recovery times were 33 sec and 201 sec respectively at an operating temperature of 290 ± 7 °C. Hence, metal-metal co-doping is found to be a good strategy to improve the sensitivity of ZnO-based gas sensors. Finally, the effect of gate electrode potential on the ammonia sensing ability of ZnO at ambient temperature was also reported here. Required films were prepared by the spray pyrolysis method. The gas response of ZnO for 400 ppm of ammonia was increased from 30.292 ± 0.042 to 54.581 ± 0.062 on increasing the gate electrode potential from 0 to 24V. Hence, this will be a new finding to improve the gas response of future ZnO-based gas sensors.