Lakshminath Bezbaroa Central Library Digital Repository
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- This digital archive comprised of the Institutes' intellectual output.
- It manages, preserves & makes available the academic works of faculty and research scholars.
- It is established to facilitate deposit of digital content of scholarly or heritage nature.
- Allowing academics & their departments to share & preserve contents in a managed environment.
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Recent Submissions
Exploiting Ring Strain in C-C and C-Heteroatom Bond Formation: Access to Spiro and Fused Indole-Based Heterocycles
(2026) Kar, Subhradeep
Chapter I covers a Bi(III)-catalyzed formal (3+2)-cycloaddition of mono-activated spirocyclopropanes with inexpensive dithianediols as the sulphur surrogates. This chapter demonstrates the de novo utilization of spirocyclopropanes as 1,2-zwitterionic synthons rather than the well-established classical 1,3-zwitterion. Chapter II describes a Cu(II)-catalyzed tandem (4+3)-annulation of 4-vinyl indoles with N-sulfonylated aziridines to afford functionalized azepinoindole scaffolds. The described protocol allows for the one-pot construction of structurally diverse core skeletons inherent in numerous natural products and bio-active molecules. Further, in presence of a chiral ligand, the asymmetric version of the protocol succeeded efficiently to produce optically active scaffolds in up to 90% ee. Chapter III describes a Cu(I)-catalyzed (4+3)-cycloaddition of 4-indolyl carbinols with N-sulfonylated aziridines to deliver privileged azepinoindole derivatives in moderate to good yields. Utilizing 4-indolyl alcohols as valuable alkylidene indoleninium ion precursors for dehydrative annulation with aziridines could lead to generation of structurally diverse biorelevant azepinoindole skeletons by suppressing the undesired Mannich (3+2)-cycloadduct. Chapter IV illustrates a Co(II)-catalyzed cascade (4+3)-annulation of 4-alkylidene indole malonates with oxiranes to deliver indole fused oxepine motifs in a diastereoselective manner. The protocol displayed broad substrate scope with respect to oxiranes and a series of substituted indolyl malonates. Moreover, with enantioenriched oxiranes, the protocol followed the chirality transfer, delivering optically active moieties in up to ≥95% ee.
Neutron Stars and Black Holes: Insights from Modified and EiBI Gravity Models
(2026) Shafeeque, Muhammed
This thesis investigates the structure and properties of compact astrophysical objects—neutron stars and black holes—within both general relativity and modified gravity frameworks. Using a combination of analytical methods and numerical computation, the work addresses critical issues such as the equation of state at extreme densities, the role of alternative gravity theories in supporting massive stars, and the existence of scalar fields around black holes in light of classical no-hair theorems.
Adaptive Sequential Multiple Assignment Randomized Trial Designs
(2025) Ghosh, Rik
Sequential Multiple Assignment Randomized Trial (SMART) is an experimental trial framework for evaluating multiple adaptive interventions that tailor treatment sequences to individual responses over time. Traditional SMART designs rely on fixed (non-adaptive) randomization probabilities at each stage and fail to leverage information accumulated during the trial. This may raise ethical concerns by continuing to allocate participants to inferior treatment options. This thesis presents a comprehensive methodology for developing optimal adaptive randomization in SMART designs to enhance both ethical and statistical efficiency. The primary contribution of this work is the derivation of optimal adaptive allocation ratios and procedures for two-stage SMART designs, applicable to both binary and continuous primary outcomes. Building on optimal adaptive randomization theory for two-arm randomized controlled trials, we formulate constrained optimization problems that minimize the total expected number of treatment failures for a binary outcome, subject to fixed asymptotic-variance constraints for prespecified objective functions. For continuous outcomes, the objective function differs. Optimal second-stage allocation ratios are first obtained and are then recursively propagated backward to derive the optimal first-stage allocation.
Machine Learning-Based Design of Critical Raw Material (CRM)-Free Multi-Principal Element Alloys (MPEAs)
(2025) Singh, Swati
This thesis presents a comprehensive, multi-pronged computational strategy for the accelerated and sustainable design of multi-principal element alloys (MPEAs), addressing the challenge of navigating an enormous compositional space (~10100 combinations) with limited high-quality experimental data. A machine learning (ML) framework was developed using exclusively experimental data from a consistent synthesis route (melting and casting), avoiding synthetic data augmentation to ensure model robustness and generalizability. Benchmarking revealed that while synthetic augmentation may boost accuracy, it undermines reliability in imbalanced datasets. The resulting framework demonstrated superior generalizability for phase prediction, guiding pre-experimental alloy design. For mechanical property prediction, an open-source toolkit, MAST-ML, was employed to assess the robustness and limitations of standard ML pipelines in this complex materials domain. Insights from this evaluation led to the development of a novel ML–metaheuristic optimization framework that simultaneously optimized yield strength, ultimate tensile strength, and elongation, addressing the longstanding strength–ductility trade-off in MPEAs using ML for the first time.
Structure-based Thermodynamics of PAM Recognition by CRISPR/Cas9: Insight from Computer Simulations
(2026) Bhattacharya, Shreya
The CRISPR/Cas9 system derived from Streptococcus pyogenes (SpCas9) has revolutionized molecular biology by allowing precise and programmable editing of DNA sequences in living cells. SpCas9 is a multi-domain RNA-guided DNA endonuclease that uses a single guide RNA (sgRNA) to bind and cut DNA at locations adjacent to a protospacer adjacent motif (PAM), which consists of the three-nucleotide canonical sequence 5’-NGG-3’ (where N can be any nucleotide). The stringent PAM requirement (5’-NGG-3’) limits the range of genomic sites accessible for editing. Therefore, understanding the molecular and energetic basis of PAM recognition is crucial for the rational engineering of Cas9 variants with broadened or altered PAM specificities. Mutations in SpCas9 enhance PAM recognition; however, the relationship between these mutations, PAM recognition energetics, and atomic structure remains unclear. This thesis employs molecular simulations using precatalytic SpCas9:sgRNA:dsDNA as a template to clarify the structure-based free energy landscape related to PAM selectivity in SpCas9 and its engineered variants. Using alchemical free energy calculations, the research examines how amino acid mutations in SpCas9 affect DNA binding. Moreover, the work also explores how the PAM binding affinity of SpCas9 changes in response to mutations in the canonical 5’-NGG sequence. Results indicated that the PAM recognition by SpCas9 is influenced by the local hydrophobicity and flexibility of its binding cleft. The flexibility of protein residues facilitates new interactions, while hydrophobicity enhances these interactions in non-canonical PAM sequences, thereby broadening PAM readability. The study establishes a direct connection between the estimated energetics and the molecular structures, providing an explanation for the experimentally observed cleavage activity of SpCas9. This work establishes a clear framework for understanding PAM recognition in SpCas9, laying the groundwork for designing new CRISPR-based genome editing tools.