http://hdl.handle.net/123456789/1078 Dissertations submitted by BS-MS Students Mon, 13 Mar 2023 18:57:07 GMT 2023-03-13T18:57:07Z http://hdl.handle.net/123456789/1845 Title: High Frequency Acoustic Signal Sensing Using Light Authors: Laxman, Chavan Aniket; Biswas, Samir Kumar Abstract: Photoacoustic Imaging (PAI) is a newly emerging biomedical imaging technology where a non-invasive study of a biological sample is possible. This detection method of the generated photoacoustic signal requires small in size, highly sensitive acoustic sensors capable of detecting very low-pressure amplitude signal. Traditional material-based sensors such as PVDF and its co-polymer PZT, etc., has limited bandwidth and poor signal to noise ratio(SNR). The sensitivity of This sensor changes drastically when the size of the sensing area reduces. There is an alternative search for developing low noise, large bandwidth, and highly sensitive acoustic sensors using alternative technologies. One of the notable research directions currently evolving is the optics-based large bandwidth acoustic signal detec- tion. In this direction, our lab ’Bio-Nano Photonics Lab in IISER Mohali’ is studying a different kind of geometries to develop micron size optical element based ultrasound detector. In this thesis, an all-optical ultrasound sensor based on Fabry-Perot Interferometer and phase modulation are proposed to detect the photoacoustic signal. Both planer and suspended membrane designs are proposed, fabricated, and experimentally shown. Chemical etching, micro-machining, dip coating techniques, and standard communi- cation devices are used to fabricate the sensor. Wed, 28 Jul 2021 00:00:00 GMT http://hdl.handle.net/123456789/1845 2021-07-28T00:00:00Z http://hdl.handle.net/123456789/1844 Title: Characterization of Salmonella effector protein SteA using MS-Proteomics analysis, Flow Cytometry and Western Blotting Authors: Gajrani, Shubham; Mukhopadhaya, Arunika Abstract: Salmonella enterica serovar Typhimurium is one of the major foodborne pathogens that causes Salmonellosis in humans and Typhoid-like disease in mice. It spreads through contaminated food, poultry, eggs and meat and causes around 93.8 million cases of nontyphoidal Salmonella gastroenteritis and 155,000 deaths each year. Salmonella Typhimurium invades, survives and replicates inside host cells by effector proteins expressed by gene clusters known as Salmonella Pathogenicity Islands (SPI). Salmonella Typhimurium SteA is an effector protein under the regulation of both SPI-1 and SPI-2. SteA under SPI-1 condition performs immunosuppressive roles interfering with NFB activation pathway. To explore other possible functions of SteA, Mass spectrometry-based proteomics analysis was performed using Perseus platform. STRING network and PANTHER classification system were used to assimilate the results from Perseus analysis. The analysis indicated the possibility that SteA could be involved in host cell death pathway. Further, Initial Flow cytometry-based apoptosis detection experiments show that SteA deletion in Salmonella Typhimurium causes a decrease in apoptosis in RAW264.7 macrophages on infection. Further experiments can help consolidate results and identify targets and mechanism involved. Fri, 01 May 2020 00:00:00 GMT http://hdl.handle.net/123456789/1844 2020-05-01T00:00:00Z http://hdl.handle.net/123456789/1843 Title: Studying the Effects of High Sugar Diet Associated Metabolic Changes on the Gut Homeostasis of Drosophila melanogaster Authors: Bose, Greeshma P.; Mandal, S. Abstract: Alterations in diet have profound impact on the health of an individual. Considering the fact that diet is the major modifiable determinant of chronic diseases, through this study, we are investigating the effects of high sugar diet associated metabolism on the gut homeostasis of Drosophila melanogatster . The experimental model adopted for this study is based on recent reports wherein the fruit fly has been used to develop a diet – induced disease model. The experimental flies were reared on media containing 1 M sugar while the control flies were fed with 0.15M sugar containing media. Our results demonstrate a significant perturbation in the gut homeostasis. This includes depletion of the intestinal stem cell (ISCs) population and the enteroendocrine (EE) cells and the enhancement of the absorptive enterocytes (EC) .We also observed perturbation of the expression of JAK -STAT signaling pathway ligand Upd3 which constitutes the major mitogenic signal for the intestinal stem cell proliferation. The high sugar diet fed flies also exhibited higher glucose uptake and altered mitochondrial dynamics. The fatty acid oxidation (FAO) capabilities of these flies were also compromised suggestive of significant alteration in the metabolic landscape. Fri, 01 Nov 2019 00:00:00 GMT http://hdl.handle.net/123456789/1843 2019-11-01T00:00:00Z http://hdl.handle.net/123456789/1842 Title: Modification of electronic states of solvent sensitive probes by vibrational strong coupling Authors: Sharma, Yogendra; George, J. Abstract: In the recent years both experimental and theoretical studies observed that chemical reaction landscape can be sculpted preciously by selective vibrational strong coupling (VSC) of reactant molecules. In VSC, excited vibrational state undergoes strong coupling with IR photons (cavity modes) which leads to the formation of hybrid light-matter states known as vibro-polaritonic state (P+ and P-). In the current project, we have studied the modification of energy levels of a solvent sensitive probe, 8-Anilinonaphthalene-1-sulfonic acid (1,8-ANS) under VSC of the solvent system. It has been observed that 1,8-ANS is very sensitive to solvent environment, specifically presence of water can modify both the radiative and non-radiative decay rates of the molecules. By changing the water composition, the electronic transition energy (solvatochromism) of 1,8-ANS also getting modified. Here, we observed the fluorescence behaviour of 1,8-ANS molecule are affected by VSC of O-H stretching mode of water molecules. Concentration dependent studies show that the shift in the electronic transition energy is completely different from the non-cavity conditions. These observations open up new questions on the application of VSC for controlling bulk properties like solvent polarity and also on the modification of intrinsic behaviour of associated chromophoric systems. Sat, 28 Sep 2019 00:00:00 GMT http://hdl.handle.net/123456789/1842 2019-09-28T00:00:00Z