http://hdl.handle.net/123456789/2 2023-04-07T16:38:09Z 2023-04-07T16:38:09Z Charapale, Omkar Namdev http://hdl.handle.net/123456789/2058 2022-12-23T19:22:30Z 2022-04-01T00:00:00Z

Title: Conjugated polyacetylenes in a high-intensity circularly polarized laser Authors: Charapale, Omkar Namdev Abstract: In last decades, light matter interaction pushed to laser induced atomic and molecular electron dynamics. Solving Schr Ö dinger equation with laser purtubed hamiltonian by using Hartree-Fock theory brings a way to observe evoultion of molecular orbitals and their energies with time. Here, we have performed a computation where laser has been induced on polyacetylens with fixed nuclear states to observe effects to π electron delocalization. Molecular electron density (MED) which is scalar field and physically observable quantity is useful to gain knoweldge of chemical anologies from topological point of view. The topographical analysis brings out changes in number and nature of critical points corresponding to reorientation of electron cloud. Bond saddle which gives insightment to hypothetical nature of chemical bond and its bond ellipticity to measure anisotropy and π character were extensively studied and analysed with propogation. In the presence of laser, bond critical point between C and H approches towards H, providing charge redistribution, decrease in size of basin and AIM atomic charge and so increase in electropositive charactor for H attractor, bond polarity of C-H bond and overall acidity of molecule. Slight shift to higher intensity regime affects MED bifurcating acetylenic bcp, forming more regions, basins and active reaction sites.

2022-04-01T00:00:00Z Vedula, Sahithi http://hdl.handle.net/123456789/2057 2022-12-23T19:18:51Z 2022-04-01T00:00:00Z

Title: Attempts to identify folate transporters in saccharomyces cerevisiae / Authors: Vedula, Sahithi Abstract: Folate is an important micronutrient for all the organisms. Many prokaryotes and eukaryotes can synthesize folates de novo, but humans require a dietary intake of folates. Folate uptake in human cells is mediated by transporters on the plasma membrane namely SLC46A1 and SLC19A1, but there are no known homologs in yeast. Although yeast can synthesize folates, it can also take folates exogenously, suggesting the presence of folate transporters. Yet, folate transporters have not been identified in yeast. So, the study aims to identify folate transporters in yeast. As there were no detectable homologues of SLC19A1 and SLC46A1 in yeast, a strategy was designed making use of synthetic lethality of yeast fol2 mutant with putative transporter deletion mutants. The FOL2 gene of Saccharomyces cerevisiae encodes the enzyme GTP cyclohydrolase. Hence fol2Δ was to be created in a library of putative folate transporter deletion strains ordered from EUROSCARF. The fol2Δcassette was improved by increasing the length of the homologous region for better in vivo recombination in yeast. Yeast spotting assay was performed to examine if any of the double deletion strains exhibited growth defectsin suboptimal concentrations of folinic acid ranging from nil, suboptimal and optimal folinic acid concentrations. With fol2 deletion background, the strains with ORFs YER039cΔ, YER060w-aΔ, YJL163cΔ, YOR306cΔ, YOR071CΔ, YBR132CΔ, YBR220cΔ, YCL049cΔ, YNR062cΔ, YML038cΔ, YGL186cΔ, YDR406wΔ, YPL274wΔ, YGR260wΔ, YOL162wΔ, YIR028WΔ showed distinct slow growth compared to BY4741 with fol2∆.One possible explanation for the result is that there might be more than one folate transporter in yeast. Insilico analysis of the promoters of the major genes of folate biosynthesis pathway, namely FOL1, FOL2, FOL3, MTD1, DHFR, MET7 was performed for four Saccharomyces species i.e. Saccharomyces cerevisiae, Saccharomyces paradoxus, Saccharomyces mikatae, Saccharomyces bayanus to identify some conserved boxes. Though some conserved regions were identified no region was conserved across the genes highlighting that the genes are regulated via different modes if at all any regulation exists. Further narrowing down to FOL2 gene promoter to check it is regulated in the presence of folinic acid. 800bp upstream of FOL2gene was cloned under lacZ reporter gene. Currently, I am testing it for positive clones; the cloning is ongoing, and assay will be performed after that.

2022-04-01T00:00:00Z Samantaray, Abhinna Sundar http://hdl.handle.net/123456789/2056 2022-12-23T19:14:45Z 2022-04-01T00:00:00Z

Title: Multi-wavelength study of magnetic cataclysmic variables using astrosat Authors: Samantaray, Abhinna Sundar Abstract: Magnetic Cataclysmic Variables (MCVs) are the semi-detached binary systems where the primary White Dwarf (WD) accretes matter from the Roche-lobe filled secondary main sequence star. MCVs can be classified into Polars and Intermediate Polars (IPs) on the basis of magnetic field strength of the WD. MCVs emit over broad wavebands due to the continu- ous interaction between the two components. These systems provide a better understanding of the nature of accretion in the presence of magnetic fields & can be used to understand their evolutionary states. This thesis outlines the multi-wavelength study of three MCVs using AstroSat. These are AR UMa (Polar), QS Tel (Polar), and 1RXS J161935.7+54630 (Polar/Asynchronous Polar). To accomplish our aim, we used AstroSat space observatory for observations in Near UV, Far UV and Soft X-rays. A detailed temporal and spectral analyses was performed for the three MCVs. By observing in both UV and X-ray regimes, we co-relate spectral energy distributions, fluxes, and spectral variations of these systems. AR UMa (AR Ursae Majoris) has the strongest magnetic field found in an accreting Polar. From timing analysis, we found that its orbital period is P Ω = 1.93 hrs, consistent with the literature. The mean AB magnitude was estimated to be 16.18 ± 0.20 in NUV and 15.95 ± 0.28 in FUV region. AR UMa was not detected in soft X-rays and was in its ‘faint’ state during the observation period. 1RXS J161935.7+524630 (DDE 32), a newly discovered MCV located in the constellation of Draco. It is very first time that the Multi- wavelength study is performed on this system. The orbital period of this MCV was found to be 2.01 hrs. The source was in low accretion state with mean AB magnitudes of 19.27 ± 1.20 and 20.31 ± 0.93 in NUV and FUV regimes respectively and was X-ray silent too. Lastly, we also observed QS Telescopii (QS Tel), a MCV containing 50 − 80 MG White Dwarf, lies in the period gap of CVs having an orbital period of P Ω = 2.32 hrs. We found that this system was in its low state during AstroSat observation with mean AB magnitudes of 17.08 ± 0.17 in NUV and 17.06 ± 0.54 in FUV filters. This was the only source observed in soft X-rays with black-body temperature of 0.09 keV and thermal plasma temperatures of 0.57 & 20.7 keV from post-shock region, for hydrogen column density of 4.38×10 20 cm −2 . The X-ray luminosity of the source was 2.23 × 10 30 ergs s −1 .

2022-04-01T00:00:00Z Mishra, Akhil Ratan http://hdl.handle.net/123456789/2055 2022-12-23T19:10:25Z 2022-04-01T00:00:00Z

Title: Meidcal image processing: denoising dynamic perfusion MRI (DCE-MRI) data using AI Authors: Mishra, Akhil Ratan Abstract: Dynamic Contrast-Enhanced MRI (DCE-MRI) has been established as a non-invasive imaging technique which is extensively used to quantitatively evaluate tumour biology in many physiological and pathological cases. The dynamic scans are then used to quantify the permeability of the contrast agent to the Blood-Brain Barrier (BBB) by extracting the pharmacokinetic parameters. However, the DCE-MRI concentration curves (C(t)) are prone to Gaussian and Rician noise. In this study, an attempt is based to understand the variation of different Tracer Kinetic Parameters (TKP) at various noise levels. Further, state of the art deep learning-based denoising systems were trained to capture the different noise levels and characteristic shapes of the C(t) in an attempt to reduce the noise found in the real dataset. For training as clean signals (ground truth) are not available, the Generalized Tracer Kinetic Model (GTKM) with non-linear dynamics was used to generate pragmatic training data. The results of this study reveal the dependence of TKP on noise levels. It was also found that deep denoising systems were able to bring down the inherent noise in the C(t) curves from the Gray Matter and White Matter in the real dataset. This is validated by the improved Signal to Noise Ratio (SNR) and increase in the similarity index of the concentration curves of neighbouring voxels.

2022-04-01T00:00:00Z