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2017 - 201912020 - 20224
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Subject: Basic Sciences × Start date: 2016 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Nuclear reactions relevant to fusion reactor candidate materials
    (G. B. Pant University of Agriculture & Technology, Pantnagar, Uttarakhand. PIN 263145, 2022-09) Navita; Joshi, G.C.
    There is a possibility to develop the fusion reactors which may offers the prospect of a long-term energy production. For the development of a fusion reactor the reactor material should have low radioactivity and high capacity to endure neutron flux. To predict material damages by nuclear reactions and model the reactor design, accurate and high-quality cross-section data are required. The present study is motivated to investigate the production cross-section of 53Mn due to neutron induced reactions on stable and unstable target nuclei as well as charge particle induced reactions on stable target nuclei with the help of a nuclear modular code TALYS-1.9. It is observed that neutron as well as charge particle induced reactions play an important role in the production of 53Mn. Moreover, the production cross-sections of 54Mn, 55Fe, 59Ni and 60Co via charged particle induced reactions have been calculated by TALYS-1.9. Default input parameters and all the six ldmodels have been used in the calculation of production cross-sections. The contribution of direct, pre-equilibrium and compound nucleus reaction to the total reaction cross-section are also studied and it is found that the contribution of compound nucleus reaction is high in comparison to direct and pre-equilibrium reaction. Energy differential cross-section (EDX) and double differential cross-section (DDX) of the natural Molybdenum for (n,xp) and (n,xα) reaction at 14.1 MeV neutrons energy has been calculated by optimizing input parameters of TALYS-1.9. From EDXs calculation, it is found that most of the outgoing protons and alpha particles have energy 5 MeV and 13 MeV respectively. DDXs calculated at 10º, 30º,60º, 90º and 120º shows anisotropical distribution of outgoing proton and alpha particles. In addition to the above, recoil spectra, displacement per atom cross-section and gas production (hydrogen and helium) cross-section for 90Zr, 93Nb, 98Mo, 180Hf, 181Ta and 184W have been calculated to estimate the reactor material damage. NRT method has been used to calculate displacement per atom cross-section. Recoil spectra show that (n,n’) and (n,2n) reaction channels are major cause to produce recoil nuclei. Gas production (hydrogen and helium) cross-section infers that production cross-section of hydrogen is higher than the production cross-section of helium. From above, it is concluded that nuclear modular code TALYS-1.9 is a powerful code to predict the cross-sectional data of long-lived radionuclides induce by neutron as well as charged particles and damage produced during reactor operation, which is important to develop fusion reactor design.
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    ThesisItemOpen Access
    Study of 120 MeV silver ion iradiation effects on the properties of co- substituted copper ferrite/ polypyrrole nanocomposites
    (G.B. Pant University of Agriculture and Technology, Pantnagar, District Udham Singh Nagar, Uttarakhand. PIN - 263145, 2022-05) Dhyani, Reena; Srivastava, R. C.
    Present work is an attempt to observe the properties of CoxCu1-xFe2O4 (x= 0.0, 0.5 & 1.0), polypyrrole (PPy), Co0.5Cu0.5Fe2O4/PPy nanocomposites and to study the effect of 120 MeV Ag ion beam irradiation on the properties of synthesized samples. The simple and cost effective methods were utilized for the synthesis of CoxCu1-xFe2O4 (x=0.0, 0.5 & 1.0), PPy and Co0.5Cu0.5Fe2O4/PPy nanocomposites (consisting 25, 50 & 75% of PPy). XRD, FTIR, Raman, UV-Visible, SEM, EDX, and VSM characterization techniques were used to determine the properties of the synthesized samples. Electrical properties were investigated by using dielectric and resistivity measurement. XRD pattern confirmed the successful formation of all synthesized samples. The overall magnetic and dielectric properties of Co0.5Cu0.5Fe2O4 (CCF) sample is superior to CuFe2O4 and CoFe2O4. For CoxCu1-xFe2O4 (x=0.0, 0.5 & 1.0), the P-E loop is almost a circle which shows the presence of weak ferroelectric behaviour. In CCF/PPy nanocomposites the magnetic parameters were found to reduce with increasing the wt % of PPy. The EPR line width gets narrower and resonance magnetic field is shifted towards the lower values as the wt % of PPy is increased. The improved thermal stability was observed for CCF/PPy nanocomposites in comparison to PPy. Further,120 MeV Ag ion beam at fluence of 1×1012 ionscm-2, 5×1012 ionscm-2, and 1×1013 ionscm-2 with a fixed current of 1pnA were used to irradiate the CCF, PPy and CCF/PPy nanocomposite (consists of 50 % PPy). From XRD analysis of irradiated samples, it was confirmed that neither crystal structure was disturbed nor any new phase formed upon SHI irradiation. After irradiation, the crystallinity of CCF and CCF/PPy nanocomposites was reduced while improved crystallinity was observed for PPy. FTIR and Raman spectra of irradiated CCF and CCF/PPy nanocomposites show a slight shift in band positions relative to their pristine samples. The sensitivity of various Raman modes is different at different fluence of SHI. A significant change was observed in FTIR and Raman spectra of irradiated PPy at the highest fluence of 1×1013 ionscm-2. It assured instability of PPy toward the high fluence of SHI. The saturation magnetization of CCF was reduced up to fluence of 5×1012 ionscm-2 and starts to increase at 1×1013 ionscm- 2. In irradiated CCF/PPy nanocomposites, the condition of magnetic saturation was not achieved, although a complete hysteresis loop was observed. In CCF/PPy nanocomposites, the narrowing effect of EPR line width indicates increased intraparticle superexchange interaction upon SHI irradiation. The overall outcomes suggest that microstructure plays dominating role in deciding the behaviour of target material towards the irradiation.
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    ThesisItemOpen Access
    Comparative study of chemically and green synthesized sulphur nanoparticles
    (G. B. Pant University of Agriculture and Technology, Pantnagar, 2022-03) Himanshi; Joshi, Deepika P.
    The present work is a comparative study of chemically and green synthesized sulphur nanoparticles. In the chemical method, sodium dodecylbenzene sulphonate (SDBS) has been used as a capping and stabilizing agent, while in green synthesis, Catharanthus roseus, Aloevera, Ocimum basilicum and Syzygium cumini leaves extract have been used as a surfactant. Citric acid and oxalic acid have been used to provide the acidic medium throughout the process. A total of eight combinations have been used to find the best among green synthesized sulphur nanoparticles. UV-Vis, XRD, FTIR, SEM and EDX characterization techniques have been used to study the attributes of sulphur nanoparticles. It has been found that sulphur nanoparticles synthesized using Syzygium cumini leaves extract in both acidic mediums are smaller, uniformly distributed and spherical, but the sulphur nanoparticles synthesized using oxalic acid have the smallest crystalline size. Further, a comparative study has been carried out between the chemically synthesized sulphur nanoparticles and green synthesized sulphur nanoparticles using an appropriate combination, which revealed that green synthesized sulphur nanoparticles are more crystalline and have a small crystalline size with high crystallinity index. Thereafter, the reducing agent has been replaced with green acid(Lemon juice) and a comparative study has been carried out in combination with SDBS and Syzygium cumini leaves extract. Syzygium cumini leaves extract shows better capping and stabilizing activity with lemon extract as compared with SDBS. Pure green synthesized sulphur nanoparticles are small and evenly distributed. The study has been extended to assess the comparative antifungal efficacy of chemically and green synthesized sulphur nanoparticles. It has been observed that sulphur nanoparticles synthesized using pure green extract(Syzygium cumini and lemon juice) are more compatible with the biological system in comparison to all other combinations.Therefore these green synthesized sulphur nanoparticles can be the better alternatives for getting disease free and high- yield crops without compromising with the natural habitats.
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    ThesisItemOpen Access
    The effect of gamma ray and electron beam irradiation on SnO2/rGO nanopellets for gas sensing applications
    (G.B. Pant University of Agriculture and Technology, Pantnagar, District Udham Singh Nagar, Uttarakhand. PIN - 263145, 2022-03) Singh, Jagat Pal; Joshi, G.C
    In the present study, SnO2/rGO and Co@SnO2/rGO nanopowder have beensynthesized through a co-precipitation technique followed by the formation of nanopellets using a hydraulic press machine. The nano-pellets have been irradiated by gamma rays with doses of 30, 60, 120 and 240 kGy and with electron beams with doses of 150 kGy and 300 kGy. The developed nano-pellets have been used to investigate the sensing of CO2 gas. To evaluate the effect of γ-ray and electron beam irradiation on the structural, morphological, optical and electrical properties of the irradiated nano-pellets analyzed by XRD, UV-Vis, FTIR and FESEM. The XRD results showed that the crystallite size decreased as the radiation dose increased. The OBG of the unirradiated SnO2/rGO and Co@SnO2/rGO nano-pellets has been calculated to be 3.58 eV and 3.25, respectively, by Tauc plot analysis. When the dose of gamma rays increased from 0 kGy to 240 kGy, the OBG of SnO2/rGO decreased from 3.53 eV to 3.11 eV and that of Co@SnO2/rGO from 3.25 eV to 2.64 eV. After electron beam irradiation the OBG for SnO2/rGO decreased from 3.53 eV to 3.19 eV for the 150 kGy and 300 kGy doses, respectively, and from 3.25 eV to 2.93 eV for Co@SnO2/rGO. The increase in conductivity has been detected by the I-V characteristics with increasing irradiation doses. At a temperature of 30 °C, the effects of gamma rays and EB irradiation on CO2 gas sensing have been investigated at 10 ppm, 20 ppm and 30 ppm concentrations. For 10 ppm of CO2, the sensitivity of gamma ray irradiated SnO2/rGO has been found to be increased from 1.06 to 1.25, and that of Co@SnO2/rGO found to be increased from 1.58 to 3.42. At the EB irradiation doses of 0, 150, and 300 kGy the sensitivity of SnO2/rGO increased as 1.06, 1.10 and 1.2, respectively, for 10 ppm carbon dioxide gas, while the sensitivity of Co@SnO2/rGO has been found to be 1.58, 3.25 and 5.25, respectively. The strategy presented here demonstrates that γ-ray and electron beam irradiation is a potential approach to improve the structural, optical, electrical and gas sensing properties of SnO2/rGO nano-pellets.
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    ThesisItemOpen Access
    Studies on mutagenic effects of gamma radiation and ethyl methane sulphonate on qualitative and quantitative traits in Tagetes patula L. (French Marigold)
    (G.B. Pant University of Agriculture and Technology, Pantnagar (Uttarakhand), 2017-01) Tripti; Chaturvedi, Preeti
    The present investigation was conducted at Medicinal Plants Research and Development Centre, G.B. Pant University of Agriculture and Technology, Pantnagar during 2014-15 and 2015-16. The experiment was laid out in Factorial Randomized Block Design (FRBD) with three replications and thirty treatment combinations, comprising of five varieties of T. patula L. viz., Safari Red, Guljafri Orange, Bonanza, Guljafri Yellow and Nana Patula Yellow, treated with five different dosage of gamma rays (2.5, 10.0, 15.0, 20.0 and 25.0 kR) and five different concentrations (0.25, 0.50, 0.75, 1.0, 1.25%) of Ethyl methane sulphonate (EMS) separately. Seed biology, vegetative, qualitative and quantitative floral characters in relation to above mentioned treatments were found to be influenced significantly by different doses/concentrations of gamma irradiation and EMS. Among physical and chemical mutagens, gamma radiations were more commodious in developing assorted beneficial traits. Data analysis of various biological parameters during M1, M2 and M3 generations showed that the impact of the mutagen did not cease in M1 but continued to effect even in M2 and M3 generations. Seeds irradiated with lower doses reflected a significant stimulatory effect on plant height, number of days for flower bud initiation and days to full bloom. It is hypothesized that low doses/concentrations of physical and chemical mutagens has the potential in modulating several vegetative and floral components which helps the plant to overcome daily stresses during growth conditions by increasing the antioxidative ability of cells and by changing the hormonal signaling in plants. Gamma irradiation also enhanced the accumulation of carotenoids in plants to protect chlorophyll from photooxidative damage under stress conditions by neutralizing the effect of singlet oxygen species. Not only this, mutagens caused difference in relative proportions of different floral pigments and markedly altered the flower colour resulting in different colour mutants of T. patula L. On the basis of flower colour variation, different mutants were documented, tagged and classified. Mutants that were consistently present in all the three generations were identified and assesement of their bioactive compounds in comparison to control was done through Gas Chromatography – Mass Spectrometry (GC-MS). Two screened flower colour mutants (NY5 and BN1) were identified from T. patula L. var. Nana Patula Yellow and T. patula L. var. Bonanza, respectively which were found persistent in M1, M2 and M3 generations. GC-MS analysis of the plants treated with gamma radiations also showed some novel and greater diversity of metabolites having important biological activities. Henceforth, gamma rays can be employed as an elicitor in inducing desired metabolic responses in plants. Concentration of lutein (carotenoid) which is highly useful in the food and pharmaceutical industries, varied in greater extent among the mutants belonging to the same variety. Thus, congenial correlation was found between lutein and different shades of colour in mutants. The results clearly recommend low doses of mutagens for stimulation in certain vegetative characters, and comparatively higher doses for qualitative and quantitative floral characters variability. However, further work is required on pigment proteiomics and metabolomics to elaborately explain the response of plant to different doses of physical and chemical mutagens. Efforts in future can be directed to metabolically engineer the plants for the production of lutein and other bioactive compounds thereby providing an opportunity to improve and stabilize desired qualitative and quantitative traits.