Lakshminath Bezbaroa Central Library Digital Repository
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Recent Submissions
Design and Development of Stereoselective Methods for C-, O-, and S-Glycoside Synthesis Utilizing Sterically Strained Nitrogen Bases and Cyclic Sulfonium Salts
(2026) Pradhan, Priyanka
The thesis focuses on the design and development of stereoselective methodologies for C-, O-, and S-glycoside synthesis, employing sterically strained nitrogen bases and cyclic sulfonium salts. Glycosylation, a cornerstone of carbohydrate chemistry, demands precise control over regio- and stereoselectivity, and this work introduces innovative catalytic strategies to address these challenges. The thesis introduces organocatalytic methods that exploit sterically strained pyridinium salts to achieve highly selective N-O-linked glycosides and establishes sulfonium-stabilized phenols as hydrogen-bonding catalysts for the strain-release glycosylation of cyclopropanated sugars, enabling access to septanoside frameworks. A palladium-catalyzed approach is also demonstrated, where proton sponge plays a unique triple role as a reductant, ligand, and base, furnishing biologically significant aryl C-glycosides with excellent yields and selectivity. In addition, new sterically hindered pyridine derivatives are synthesized and evaluated to understand the interplay of sterics, inductive, and through-space effects on basicity and reactivity, offering cost-effective alternatives to established non-nucleophilic bases. Collectively, these studies provide novel catalytic concepts, mechanistic insights, and practical synthetic applications, advancing stereoselective glycosylation and expanding the toolkit for carbohydrate chemistry and related fields.
Design of Homogeneous / Heterogeneous Interfacial Electrocataly6c Systems for Value-Added Products
(2026) Kalita, Nitul
A comprehensive overview of electrocataly0c systems for sustainable value-added product formation via water electrolysis and CO₂ reduction is presented in this work. The study focuses on the design and development of efficient catalytic interfaces, functional membranes, and hybrid reaction environments to achieve improved charge separation, accelerated reaction kinetics, and enhanced product selectivity. Emphasis is placed on understanding the mechanistic aspects of hydrogen and oxygen evolu0on reactions, highlighting the significance of interfacial charge transfer and catalyst–electrolyte interac0ons. The role of bipolar membranes in promoting water dissociation and maintaining dis0nct pH conditions is explored as a strategy to achieve efficient ion transport and separa0on of HER and OER processes. Furthermore, the inves0ga0on extends toward CO2 electroreduction, where synergistic homogeneous–heterogeneous interfaces enable selec0ve conversion of CO2 into value-added fuels. Overall, the study establishes a unified approach combining catalyst design, interfacial engineering, and membrane op0miza0on to advance integrated electrochemical systems for sustainable energy generation and carbon utilization.
Development of aptasensors for detection of Shiga like toxin 1 (Stx1) and Shiga like toxin 2 (Stx2) from Escherichia coli
(2026) Mili, Malaya
Shiga toxin-producing Escherichia coli (STEC) are among the leading causes of foodborne illnesses worldwide, contributing to significant morbidity and mortality. The Shiga-like toxin 1 (Stx1) and Shiga-like toxin 2 (Stx2) expressed by STEC are the main virulence factors responsible for bloody diarrhoea, haemolytic uremic syndrome (HUS), and haemorrhagic colitis (HC). The severity of the diseases necessitates rapid, sensitive, portable, and low-cost diagnostic tools to strengthen on-field food safety monitoring, improve disease prognosis and guide timely intervention. Current detection methods typically involve culture-based identification, PCR-based molecular diagnostics and antibody-based immunoassays. These methods involve complex procedures, long assay times, and require advanced instrumentation as well as trained personnel. Moreover, antibody production is costly, prone to batch-to-batch variability, and antibodies often lose activity under fluctuations in temperature, pH, or storage conditions. These limitations hinder their applications in point-of-care settings, where the on-field conditions vary, and the standard storage conditions are not always feasible to maintain. Aptamers, owing to their high selectivity, strong thermal stability, low production costs, and ease of functionalization, are being increasingly recognized as ideal biorecognition elements for biosensing applications. In this thesis work, aptamer-based impedimetric biosensors for the detection of Stx1 and Stx2 were developed using interdigitated microelectrodes and their sensing performances were evaluated using electrochemical impedance spectroscopy (EIS). The aptasensor for Stx1 was fabricated using a highly selective aptamer developed via standard Systematic Evolution of Ligands by Exponential Enrichment (SELEX) method. The aptamer was characterized, and then immobilized on a chain-type interdigitated microelectrode to develop the aptasensor. The microelectrode was fabricated following advance techniques such as electron beam deposition, chemical wet etching and photolithography. The developed aptasensor exhibited a limit of detection (LOD) of 2.88 pM, a linear dynamic range of 10 - 450 pM and a sensitivity of 107.02 Ω/pM. To validate the practical application of the aptasensor it was tested in real sample using cow milk. The sensor showed the recovery in the range of 97.5% to 103.5%. In the next phase of the work an aptamer against Stx-2 was developed. In this part of the work, the aptamer was however, identified from a computationally designed aptamer library following a systematic in-silico approach comprising of generation of aptamer library, prediction of secondary and tertiary structures of the aptamers, molecular docking, and molecular dynamic simulation. The selected aptamer was validated using circular dichroism (CD) and isothermal titration calorimetry (ITC). The in silico designed aptamer for Stx2 was then used as the biorecognition element for the development of the Stx2 biosensor using a wave-type interdigitated microelectrode. The wave type microelectrode fabrication followed the same techniques described for the chain type electrode. The developed sensor exhibited an LOD of 4.63 pM, a linear range of 10 – 400 pM and a sensitivity of 97.03 Ω/pM. To validate the practical application of the aptasensor it was tested in real sample using cow milk. The sensor showed recovery in the range of 93.06% to 108.4%.
Interplay of Topology, Localization, and Non-Hermiticity in Low-dimensional Systems realized through Electrical Circuits
(2026) Halder, Dipendu
Topology has revolutionized the understanding of condensed matter systems by revealing phases of matter characterized by global invariants rather than local order parameters. The inclusion of non-Hermiticity, arising from gain, loss, and non-reciprocal interactions, enriches this framework by introducing unique phenomena such as exceptional points, non-Hermitian skin effects, generalized Brillouin zones, and modified bulk boundary correspondence. In parallel, topolectrical circuits have emerged as a versatile and experimentally accessible platform for realizing and probing such topological systems.
Effective Field Theories to Probe Physics Beyond the Standard Model at Colliders
(2026) Sarkar, Abhik
Physics beyond the Standard Model (BSM) is motivated from several observations like that of tiny but non-zero neutrino masses, evidences of a dark matter, matter-anti- matter asymmetry, stability of the Higgs vacuum, heirarchy problem, and many more. But, since the discovery of the Higgs boson, searches for TeV-scale New Physics (NP) at the Large Hadron Collider (LHC) have largely yielded null results, thereby placing significant constraints on fundamental theories that predict new resonances at the TeV scale. In this context, where no substantial increase in the LHC energy is expected in its future run, and relatively lower energy but high precision lepton colliders are on the horizon, Effective Field Theories (EFTs) emerge as a powerful and pragmatic framework for probing the effects of NP that remain kinematically inaccessible and thus manifest only virtually. The thesis explores the prospects of applying EFTs, with particular emphasis on the Standard Model Effective Field Theory (SMEFT), wherein the Standard Model (SM) is extended by higher dimensional effective operators constructed from its fields abiding by the SM gauge symmetry. We study several applications of SMEFT, where the deperture from the SM observation can hint towards the existence of NP. We investigate modifications to the Higgs boson couplings with SM gauge bosons, as well as flavor violating effects that are highly suppressed in the SM. In addition, we employ the Dark Matter Effective Field Theory (DMEFT) framework, which extends the SM by introducing a Dark Matter (DM) candidate whose interactions with SM fields are mediated by higher dimensional operators. While accounting for the observed DM relic abundance such operators can also encode imprints of the early Universe when produced during the reheating era, which may be probed through their signatures at the future collider experiments.