Lakshminath Bezbaroa Central Library Digital Repository
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Recent Submissions
(An) Electrocardiogram Based Secure Person Adaptive Cardiovascular Disease Diagnosis System
(2024) Jyotishi, Debasish
The electrocardiogram (ECG) signal is the primary non-invasive diagnostic tool used by cardiologists for diagnosing cardiovascular diseases (CVDs). Timely identification of CVDs is critical for effective treatment and prevention of fatalities. The automated diagnosis of CVDs is crucial in assisting cardiologists and facilitating remote monitoring; contributing to the advancement of AI-based healthcare. However, the significant challenge lies in the inter-individual variability of morphological characteristics in the ECG signal, necessitating the development of a person-adaptive CVD diagnosis system. Additionally, automated diagnosis brings with it security and privacy considerations concerning wearable healthcare devices and the handling of sensitive medical data. This thesis work aims to learn deep temporal and spatio-temporal representations from multi-lead ECG signals with the overarching goal of developing an automated CVD diagnosis system and a robust biometric system. Additionally, a novel method is proposed to effectively leverage learned personspecific representations for the development of a person-adaptive CVD diagnosis system. In our first work, an ECG based person identification and verification system is developed by learning the underlying temporal representation of the ECG signal. A biometric system based on long shortterm memory (LSTM) network is designed for explicitly learning the temporal representation. Further, a novel attention based hierarchical LSTM (HLSTM) model is designed to learn the temporal variation of the ECG signal in different abstractions. Empirical findings demonstrate substantial performance enhancements by using multi-scale temporal information. In the second study, the multi-scale temporal dynamics learning network (MSTDLNet) is introduced to concurrently capture the local morphological representation and multi-scale temporal dynamics in the ECG signals for biometric applications. The experimental findings affirm that the multi-scale temporal representation learned by MSTDLNet yields robust and persistent performance, significantly improving outcomes in multi-session analyses. In the third work, an automated CVD diagnosis system using multi-lead ECG signal is proposed. Specifically, an attentive spatio-temporal learning network (ASTLNet) is developed to learn better diagnostic representation by exploiting the concurrent spatio-temporal variation of a multilead ECG signal.
Development of Kaolin-based Microporous Membrane for Energy Efficient Microalgal Harvesting and Effluent Recycle Under Circular Bioeconomic Approach
(2024) Agarwalla, Ankit
Biodiesel as a renewable energy source can provide an alternative to the alarmingly depleting energy from fossil fuels. Microalgae is an encouraging third-generation feedstock for the production of biodiesel as it has the capability of oil production throughout the year. Besides several advantages, commercial production of microalgal biomass feedstock is not considered sustainable due to its high production cost. In this context, recycling the culture media carry significant potential to reduce the overall cost for the long-term growth of microalgal industry. In this work, indigenous low-cost disc and tubular membranes were fabricated using naturally available kaolin as the key precursor. Different composition of kaolin (80-92 wt.%) and binder (8-20 wt.%) was used to optimize the raw material and binder composition. The optimized binder concentration in disc membrane was used to further fabricate tubular membranes. With increase in binder percentage from 8% to 20% in disc membranes, the percentage porosity, average pore size and water permeability decreased from 34.52% to 21.5%, 2.28 μm to 0.195 μm and 6.12×10-9 to 1.69×10-9 m Pa-1 s-1 respectively while flexural strength increased slightly from 7.1 MPa to 9.4 MPa. Hence, binder percentage of 8% i.e., 2% boric acid, 2% sodium metasilicate and 4% sodium carbonate was found to be optimum. Thereafter, tubular membranes will be fabricated using this binder concentration. The fabricated tubular membranes had porosity of ~26% - 47%, a pore diameter of 0.123-0.182 μm, water permeability of 4.2×10-8 – 17.1×10-8 m3 m-2 s-1 kPa-1, along with good mechanical and chemical strength.
Nanotechnology-based Drug Repurposing for Potential Theranostic Applications
(2024) Choudhury, Konika
This thesis includes exploratory, experimental and quantitative studies. It aims at extrapolating the benefits of drug repurposing through the nano realms. While nanomaterials help with stability, solubility and selectivity; repurposed drugs are sustainable and safe. Together, they can smoothen the edges of a therapeutic module that would otherwise be unreliable. Since inflammation is often correlated with cancer, the anti-proliferative potential of antihistamines was explored. Following the experimental screening of several over the counter drugs, promethazine hydrochloride and levocetirizine dihydrochloride were sieved in. Further investigations demonstrated promethazine’s obvious potential against triple-negative cancer and levocetirizine’s against lung adenocarcinoma. Additional studies also demonstrated promethazine’s remarkable anti-bacterial abilities. Thus, augmenting the idea of repositioning with nanotechnology can present a sustainable and workable strategy. Altogether, we are hopeful that the numerous findings from this thesis will pave certain prospects for future investigations that further cement the faith in repurposing.
Thermal (Photo) Induced Selective C-H Bond Functionalization/Oxidative Cyclization in Di-Nitrogen Benzenoid Heteroarenes
(2024) Ghosh, Subhendu
This thesis demonstrates a number of thoughtful approaches for selective C-H functionalization and oxidative annulation strategies under thermal(photo) catalytic architectures. This thesis has been divided into five major chapters and extended toward a future perspective. Chapter IA gives a concise overview of Transition-metal catalyzed C-H functionalization and oxidative annulation (cyclization). Meanwhile, Chapter IB depicts the different photo-induced C-H functionalization and cyclization techniques. Chapter II demonstrates Ru(II)-catalyzed regioselective C-H/N oxidative annulation of 2-arylquinoxalines with internal alkynes. In this chapter, the synthesized quaternary annulated adducts are extensively scrutinized for detailed photo-physical applications. Such donor--acceptor type molecules exhibit Aggregation Enhanced Emission (AEE) in DMF/water solvent systems. Apart from this, such annulated adducts possess reversible mechanochromism. Such small quaternary salts are utilized for latent fingerprint detection (up to 2nd level). Furthermore, such luminogens serve as cellular imaging probes. Chapter III describes a solvent-switched regiodivergent CH malemidation on 2-arylimidazopyrdines under Mn(I)-catalysis. This protocol enables selective C-H alkylation without the involvement of silver or oxidants. Before this work, Mn(CO)5Br is known for the directed C-H functionalizations. In this chapter, a non-directed CH metalation of Mn(CO)5Br apart from the directed strategy has been revealed. Chapter IV offers the regioselective C-H maleimidation at the unattained C3-H site of 2-aryl quinoxalines. Herein, the non-directed Mn-catalysis enables the challenging C3-H activation over the usual ortho CH activations. Besides these, the synthesized C3-maleimidated quinoxalines exhibit PIFA-promoted electron-drifted Spirocyclization at room temperature. Also, in the presence of Selector, the C3-maleimide quinoxalines undergo dehydrogenation of succinimides ring. Chapter V represents a reagent-less photo-induced auto-catalyzed oxygenation at sterically hindered C(sp3)-H site. This photochemical “reagent-less” solvent-dependent hydroxylation at Csp3-H and spiro-etherification involving C(sp3)-H/C(sp2)-H are unparalleled. Herein, the N-H tautomer of C3-maleimidated quinoxalines acts as a triplet sensitizer and transfers its energy to a triplet oxygen (3O2) generating reactive singlet oxygen (1O2) which facilitates oxygenation reactions at the other C(sp3)-H sites within the molecule making it a true auto-sensitized process. This photo-oxygenation represents an illustration of a tautomer-assisted 1O2 uptake
Analysis of GLARE Laminates Under Low Velocity Impact
(2023) Kakati, Sasanka
Superior impact properties of glass aluminium reinforced epoxy (GLARE) have led to their usage in impact prone structures such as aircraft fuselage, wings and cargo panels. However, these advanced laminated structures are also susceptible to impact induced damages, especially under low velocity impact (LVI) where the damages are sub-surface and barely visible. Finite element analysis (FEA) enables a more in-depth study of the complex nature of the response and damages due to arbitrary LVIs. This dissertation thus presents the FEA of GLARE under LVI, evaluating the response of the target and the associated damage due to LVI. A complete 3D finite element (FE) formulation has been developed using 3D layered solid elements to evaluate the contact impact response of GLARE subjected to arbitrary (normal and oblique) LVIs. A transient dynamic FE code has been developed incorporating the Newmark-β method and implementing suitable normal and tangential contact models for accurate determination of the contact responses and the associated interfacial delamination damages. An important aspect of the present FE modelling is the incorporation of an adjustable contact stiffness based on the impactor to plate mass ratio which is critical for accurate evaluation of the contact response and correctly predicting the associated damages. Influence of important parameters like properties and geometry of the GLARE laminate and the impactor along with the trajectory of the impact on the contact impact response and the delamination damages have been investigated. Results from the present work show that besides the size and geometry of the impactor, the trajectory of the impactor relative to the target and the coefficient of friction between them also significantly influence the contact response as well as the evolution of delamination at the interfaces. Further, for multiple impacts, the interval between the successive impacts greatly influences the magnitude of contact force as well as delamination at the fibre-metal interfaces. The presence of discontinuities in the form of cut-outs or open holes (due to functional requirements) in the GLARE laminate significantly influences how delamination grows around these locations due to increased stress concentrations under impact loads. Results from the analysis of LVI show that the pitch of the cut-outs and their size and shape has significant influence on the evolution of delamination, especially at the metal/composite interfaces.