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Hardware Design for Predicting Early Signs of Sudden Cardiac Arrests from ECG Signals
No full textElectrocardiogram (ECG) is a non-invasive way to record the electrical activities of the heart and is recognized by its features, P-QRS-T. Any change in the amplitude or duration of these features indicates the presence of an abnormality, known as cardiac arrhythmias (CA). Among the most fatal CAs, sudden cardiac arrests (SCA) can cause death unexpectedly if left untreated, and hence, their early prediction is important to receive timely medical care. SCAs can be predicted by the detection of one of the most life threatening CAs, known as ventricular tachycardias (VT), which are characterized by the presence of three or more consecutively occurring premature ventricular contraction (PVC) beats in an ECG signal. PVCs are common among the general population, but they pose a threat to the human heart only if they occur frequently in a group of three or more with varying QRS morphologies. Based on the QRS morphology, PVC beats are classified as multifocal or unifocal, and based on the frequency of occurrences, PVCs are classified as ventricular bigeminies, ventricular trigeminies, non-sustained ventricular tachycardias (NSVT), and sustained ventricular tachycardias (SVT). However, according to medical experts, the highest risk of SCAs is related to frequent episodes of multifocal NSVTs and SVTs. On the other hand, ventricular bigeminy and trigeminy are not directly related to any fatal CAs, but they will require further medical aid if they occur frequently enough to prevent the heart from pumping the required amount of blood to all the organs of the body. In this work, a hardware-efficient FPGA-based design for predicting the early signs of SCAs is proposed by detecting PVC beats and classifying them into six major categories of ventricular arrhythmias (VAs), namely multifocal PVCs, unifocal PVCs, ventricular bigeminies, ventricular trigeminies, NSVTs, and SVTs. The SCA prediction system consists of the following stages: pre-processing, feature extraction, PVC detection, and VA classification. For pre-processing, a denoising technique using the modified lifting-based discrete wavelet transform (MLDWT) is used to combat all the ECG noises as well as enhance the QRS complexes in the ECG signal. For efficient detection of PVC beats, an accurate feature extraction stage that extracts R peaks, T peaks, and the Teager energy operator (TEO) is employed. With the extracted features, a characteristic matching algorithm is used for PVC detection, and an adaptive decision logic-based (ADL) classifier is utilized for VA classification, resulting in a detection accuracy rate of 98.2% when tested using the online ECG databases, viz., the MIT-BIH arrhythmia database (MITDB) and the MIT-BIH supraventricular database (SVDB). The complete hardware design of the SCA prediction system, when implemented on the Nexys 4 DDR Artix-7 FPGA board, outputs the number of PVCs detected and VA classified, based on which an alert on the risk of SCAs is provided while utilizing 10.4% of the total available hardware resources on the FPGA board. For future integration of the SCA prediction system into wearable healthcare devices, an ASIC implementation of the PVC detection and VA classification is performed, resulting in a place and route area of 0.02 mm2 and a power utilization of 3.47 μW at an operating frequency of 100 KHz when implemented using SCL 180 nm CMOS technology
Architectural Design of Cu-MOF Based and its Derived Bimetal- Based Nanocomposites for Sensing of Toxic Chemicals and Harmful Gases
No full textMetal-organic framework (MOF) structures are crucial in numerous fields of materials science owing to their high tunability, formed by combining different metal and organic moieties, which can be utilized for different applications. Specifically, Cu-MOFs are promising materials for gas and electrochemical sensing applications due to their unique combination of high surface area, tunable structure, redox properties, and catalytic activity. These features make them ideal candidates for use in sensors for environmental monitoring. The sensing activity as well as the stability of these materials, can be enhanced by decorating with bimetallic nanoparticles, modifying with reduced graphene oxides (rGO) supports. Additionally, another effective approach for enhancing these activities is to derive morphology and composition-tuned bimetal oxides. This consequently facilitates the development of innovative materials with encouraging properties. Keeping this in mind, the PhD thesis is focused on the architectural design of Cu-MOF-based and its derived bimetal-based nanocomposites for sensing toxic chemicals and harmful gases through the alteration in their shape, size, morphology, and the replacement of cations, achieved through various synthetic methods, leads to significant variations. Briefly, the thesis focused on two major parts. The first part includes the synthesis of Cu-based MOF and modifying it with bimetallic nanoparticles, forming its bimetallic MOF structure, deriving bimetal oxides, and finally forming composite with reduced graphene oxide for the potential electrochemical sensor of triclosan, atrazine, and clioquinol. The other part involves the synthesis of MOF-derived alloy and core-shell bimetal oxides with changes in the cation of the shell and morphology of the core for the gas-sensing application of toxic gases (NO2, CH4, and NH3). In the first project, I have demonstrated the synthesis of NiCo bimetallic nanoparticle decorated Cu-MOF modified rGO nanocomposite for electrochemical sensing of triclosan (Chapter 2, J. Electroanal. Chem. 2023, 943, 117589). After that, reducing complexity in synthesis, a one-step synthesis of CuNi- bimetallic MOF wrapped N-3DrGO was done for atrazine sensing. (Chapter 3, Manuscript Submitted). Lastly, to overcome the moisture instability and thermal stability by retaining the structure, morphology, and properties of MOF, in this chapter cation substituted Cu-based bimetallic MOF derived bimetallic oxides (CuO/NiO, CuO/ZnO, CuO/Mn2O3) modified 3DrGO nanocomposite was developed for the sensing of clioquinol. (Chapter 4, Manuscript to be submitted). The gas sensing part also includes three major chapters. In the first chapter of gas sensing, a comparison study was conducted between traditional and MOF-mediated synthesis of CuO/NiO bimetal alloy oxides decorated on rGO for NO2 sensing. (Chapter 5, ACS Appl. Electron. Mater. 2024, 6, 2349). Later, the efficiency of the core-shell structure with the varying metal ions of the shell (Zn, Ni, Co) modified with N-3DrGO was carried out for room temperature methane sensing. (Chapter 6, ACS Appl. Electron. Mater. 2025). Finally, after concluding the MOF-derived method with CuO@Co3O4 morphology showed the highest sensing performance, in the last chapter, interest was given to the synthesis of morphology varied core of CuO@Co3O4 oxides (cube, sphere, and octahedron) modified with N-3DrGO flexible sensor for room temperature ultralow level ammonia sensing. (Chapter 7, Manuscript to be Submitted). The materials discussed in this thesis have demonstrated exceptional sensitivity, selectivity, stability, efficiency, and recyclability, making them a valuable system for the aforementioned applications that hold considerable environmental importance
Exploring Molecular Intricacy: Development of Facile Carbon- Heteroatom Bonds via Oxidative Dearomatization Reactions (ODRs)
No full textIn the last few decades, oxidative dearomatization has been widely recognized as an attractive and straightforward transformation for the development of a high level of molecular complexity, as it provides an efficient method to derive three dimensional architectures from simple planar achiral substrates. Attempts to dearomatize arenols employing non-metallic reagents have been confined mostly to hypervalent iodine reagents, being to generate mostly spiro-lactones, spiro- ethers, and spiro-amines. In this context, our group with the continued interest in dearomative transformations, we started our journey through the exploration of an oxidative dearomative methodology by employing quaternary ammonium tribromides. It has been envisaged that spiro[4.5] and [5.5]trienones, the core structures of many naturally occurring compounds, can be directly accessed from dearomative spiro-annulation of ynones, biaryl ynones and appropriately substituted phenols bearing a pendant side chain. The thesis chapters highlight spiro-annulation via energetically demanding dearomatization reactions promoted by either visible-light or Lewis acid or quaternary ammonium tribromides for the formation of structurally complex spirocyles along with several carbon-heteratom bond generations. The thesis presently divided into the following six chapters. Chapter 1. Bromine induced spirocyclization of biaryl ynones facilitated the synthesis of spiro[5.5]trienones suitable for extended functionality at the C(3´) position. Herein, a step- economic photo-oxidative brominative carbannulation of biaryl ynones employing ammonium bromide and riboflavin tetraacetate (RFTA) have been developed. The reactivity between distal phenyl C-H activated ortho-annulation and dearomative ipso-annulation are well exemplified. The eminent features of the methodology include metal-free, external additive free, low-loading photocatalyst (0.1 mol%) and use of simple precursor. Chapter 2. In chapter 2, we conceptualized an efficient radical cyclization approach for the synthesis of SCF3, SAr, SO2Ar and COAr featured spirocyclic [4.5] and [5.5] trienones between biaryls and ArSO2H or ArCOCO2H in presence of RFTA as a photocatalyst and ArSSAr or AgSCF3 without photocatalyst via energetically demanding dearomatization pathway under visible-light catalysis. The unprecedented photo-excited charge transfer complex with biaryl tethered ynone provides a way to promote S-centered radical generation. Success of this approach was the wide range of sulfur centered radical generation/addition to the organic molecules/consecutive cyclization under mild conditions. Chapter 3. Sulfinyls are valuable structural moieties in the development of new pharmaceuticals and agrochemicals. In this chapter 3 of the thesis, we disclose a straightforward synthesis of functionalized spirotrienones proceeding via an unprecedented BF3.Et2O promoted spirocyclization of biaryl ynones in presence of aryl sulfinic acid. The economic availability of the BF3.Et2O to carry out transformations in bulk scale along with its further application towards the synthesis of dibenzocyclohepten-5-ones delivers a unique opportunity to utilize it in various synthetic directions. Chapter 4. An extended period of rapid growth in annulated arene heterocyles via radical route has occurred in the last few decades, leading to the synthesis of several naturally occurring compounds or biologically significant building blocks. Herein, we discover a smooth interface for the synthesis of spiro[4.5] and [5.5]trienones, a simple brominative (PART I) and thiolative (PART II) addition of alkynoates by oxidative spirocyclization. A simple protocol which leads to exclusive formation of C(3´)bromo spiro[4.5]trienones and C(3´)thiomethyl spiro[5.5]trienones from biaryl substrate, where it endures a regio-selective spirocyclization in presence of corresponding electrophiles. The methodology features a broad scope of biaryl substrates into challenging spirocyclic cores with good functional group tolerance and operates under mild metal-free conditions. Chapter 4.1. In this sub-chapter, a convenient and generalized method for in situ tribromide generation was studied and with this strategy we developed a wide variety of brominative spiro[4.5] and [5.5]trienones. Figure 4. Graphical abstract for chapter 4.1 Chapter 4.2. In this sub-chapter, an efficient and metal-free dearomative cationic approach is achieved for the synthesis of thiomethylated spiro[5.5]trienones from biaryl ynones and 1,1,2- trimethyldisulfan-1-ium as a source of thiomethyl cation. Chapter 5. A wide range of spirolactams were synthesized with good yields and regio-selectivity through a step-up oxidative dearomatization of readily available arenols tethered to ester and primary amines in presence of less explored quaternary ammonium tribromides (QATBs). The probable reaction mechanism associated with tribromide triggered dearomatization reaction has been forecasted with a series of control experiments, time-dependent HRMS and DFT studies to establish the reaction mechanism 6. In this chapter, biologically valuable isocoumarins were synthesized with broad substrate scope in high yields and excellent regio-selectivity through oxidative dearomatization of easily prepared o-alkynylbenzoates and o-alkynylbenzamides employing quaternary ammonium tribromides under metal-free conditions. Besides halocyclization, this intramolecular cyclization proceeds smoothly with several chalcogen-based electrophiles for the generation of C-S, C-Se and C-Te bonds. Interestingly, under certain condition, isochromenones were obtained in presence of diorganyl disulfides with PTATB
Numerical Analysis of Time-fractional Parabolic Differential and Integro-differential Equations
No full textOver the last few decades, the subject of fractional calculus emerged in various areas of science and engineering. In this regard, fractional partial differential equations are used to describe anomalous diffusion. The main feature of the fractional differential equations is their nonlocal and heredity property, which makes their solution challenging. Moreover, the smooth initial data in a differential equation involving fractional derivatives may not provide a smooth solution. Due to such uncertain behavior, obtaining analytic solutions of the fractional partial differential equations is intricate or impossible in many cases. Consequently, efficient numerical techniques play a major role in evaluating an approximate solution of fractional partial differential equations and analyzing its asymptotic behavior. The present thesis intends to develop and analyze some efficient and stable numerical schemes for solving a class of time-fractional partial differential and integro-differential equations of parabolic type in one and two dimensions. The thesis starts with a brief history of fractional calculus, followed by some preliminaries of time-fractional differential equations and the approximation techniques to obtain their solutions. This thesis can be divided into two parts. The first part is devoted to constructing some layer-adaptive numerical techniques for different classes (including linear, semilinear, time-delayed and interface models) of time-fractional partial differential models of parabolic type. In general, the typical solution to such types of problems undergoes a sharp change at t = 0, namely, the interior layer region of the domain due to the presence of the weak singularity. The traditional numerical methods on uniform mesh fail to grasp such abrupt changes inside the layer region, and they degrade the convergence rate. The layer-adaptive graded mesh with the user-chosen grading parameter is used in the temporal direction to achieve optimal accuracy. The widely-used L1 technique is employed to discretize the fractional order differential operator in the temporal direction for most of the model problems. The corresponding proposed schemes achieve a superlinear rate of convergence for suitable choices of the mesh grading parameter. In some cases, the newly-proposed L1-2 and L2-1σ technique is used in the temporal direction to construct a higher order (up to second order) scheme. The Newton linearization technique alongside the Daftardar-Gejji and Jafari method tackle the nonlinear part of the problems. The second part develops numerical techniques for the time-fractional partial Volterra integro-differential equations of parabolic type, along with their possible extensions to problems with semilinearity. The typical solution for these problems is assumed to be sufficiently smooth, subject to the prescribed initial data. For all the model problems, the fractional derivative is discretized using the L1-2 technique on a uniform mesh in the temporal direction. The composite trapezoidal rule approximates the integral part, whereas the composite product trapezoidal formula is employed to approximate the integral involving a weakly singular kernel. The classical central difference formula and the cubic B-spline collocation method are used on a uniform mesh in the spatial direction. The operator-splitting idea in time is discussed for the two-dimensional problem. To solve the resulting system of algebraic equations, the well established Thomas’s algorithm is used. On a suitable norm, the stability and convergence for all the proposed schemes are performed thoroughly under sufficient regularity assumptions on the initial data and true solution of the considered model problem. The efficiency and applicability of the proposed schemes are tested through numerical experiments. Computational results are presented through several plots and tables to support the theoretical findings. At the end of this thesis, a brief summary of the findings and the scope of further enhancement of the proposed study are provided. The novelty of these schemes is their simplicity and efficiency compared to the existing methods
Facile Low Temperature Synthesis of Bismuth Molybdate (Bi2MoO6) Based Heterostructure Materials for Photocatalytic Micropollutant Remediation and Reduction Reactions
No full textIn this thesis, various types of nano-heterostructure materials involving Bi2MoO6 as base semiconductor have been designed for water decontamination and activation of atmospheric molecules. Initially, Bi2MoO6 was synthesised by various low temperature methods. To improve the photoexcited charge carrier separation and photocatalytic activity, Bi2MoO6 was subsequently coupled with spinel metal ferrites and metal vanadates semiconductors to construct binary and ternary heterostructure materials. Further, to facilitate rapid formation of the composites, in many cases, one pot synthesis techniques were used while in some other cases, in situ synthesis method was successfully employed. In addition, defects such as doping and oxygen vacancy were introduced into the crystal structure of the composites to tailor the band positions and improve their spectral response. The prepared materials were characterized by XRD, Raman, FTIR, XPS, EPR, BET, FESEM, TEM, UV-vis DRS, PL, water contact angle and electrochemical techniques to investigate their structural, morphological, surface, photon absorption and charge separation properties. The photocatalytic activity of the materials were evaluated for decontamination of Bisphenol A, Cr(VI) and ciprofloxacin from aqueous sources and activation of atmospheric molecules like H2O, O2 and N2 to produce H2, H2O2 and NH3, respectively. In addition, numerous optimization experiments such as catalyst dosage, pollutant concentration, pH, h+ scavengers, water matrices and intervening anions were carried out. Degradation pathway of Bisphenol A and ciprofloxacin were analysed by identifying the reaction intermediates by HRMS analysis. The reactive radicals responsible for the photo-degradation reactions were identified by scavenger experiments. Further, various radical trapping studies were carried out to confirm the generation of reactive radicals such as •OH and •O2− in aqueous illuminated suspension of the photocatalysts. The band gap, band position, and type of semiconductivity of the individual semiconductors were estimated by Tauc plots, Mott-Schottky plots, and valence band spectra. Finally, by considering the band positions, XPS peak shifting, work function and radicals quenching studies, the mechanism of photoinduced charge carriers’ migration are rationally deduced for each heterostructure material to explain their photocatalytic activity. A mild reflux route was designed for facile synthesis of Bi-self doped Bi2MoO6 (BMO-A) with nanoplate morphology. Microstructural study revealed substitution of Bi5+ ions in the molybdate layer leading to partial reduction of Mo6+ to Mo5+ ions and creation of Mo vacancy. The defect engineered BMO-A exhibited improved optical and photoelectrochemical properties compared to its undoped analogue. The BMO-A material was subsequently used as host lattice for in situ construction of CaFe2O4/Bi2MoO6 0D-2D p-n heterojunctions. Well dispersed CaFe2O4 quantum dots over BMO-A nanoplates provided a strong interfacial contact conducive for fast charge mobilization. The CaFe2O4/Bi2MoO6 composites displayed improved photocatalytic performance for bisphenol A (BPA) degradation and Cr(VI) reduction with rates 5–9 times higher than pure components. The rapid production of •OH and •O2− radicals, construction of an interfacial p-n heterojunction with double charge migration mechanism accounted for the improved photocatalytic efficacy of the composite. A mild CTAB assisted one pot reflux synthesis route is designed for in situ integration of metal organic framework (MOF)-derived NiFe2O4 with tetragonal-BiVO4 and γ-Bi2MoO6 to prepare NiFe2O4/t- BiVO4/Bi2MoO6 ternary composites. Morphologically, fine dispersion of NiFe2O4 (NFO) quantum dots over Bi2MoO6 (BMO) and t-BiVO4 (BVO) nanoplates lead to microscopic heterojunction formation among BMO-BVO, BVO-NFO and BMO-NFO phases. The ternary composites displayed high surface area, strong optical absorption and superior charge mobility that accounted for its improved photocatalytic activity for ciprofloxacin (CIP) degradation (>99% in 90 min) and H2 evolution (1.11 mmolh-1g−1, photon conversion efficiency 18.5%). Kinetics study revealed 12–55 higher CIP degradation activity and 31–41 times higher H2 evolution rate in comparison to the pure semiconductors. A conjugated S-scheme charge transfer mechanism has been deduced from comprehensive band position analysis and radical trapping study to explain the enhanced photocatalytic activity. A series of Bi2MoO6/InVO4/CeVO4 ternary heterostructures were constructed by in situ deposition of Bi2MoO6 nanoplates over one pot synthesized InVO4/CeVO4 using a facile oil bath heating method. A distinct morphology consisting of Bi2MoO6 nanoplates, CeVO4 nanosheets and InVO4 nanorods was noted. The significant intergrowth among the constituent phases led to the construction of tight interfacial microscopic junctions. The ternary materials displayed intense absorption in UV–visible region, drastic decrease in charge recombination and higher excited state lifetime. Both InVO4 and CeVO4 individually as well as the ternary heterostructure contained surface oxygen vacancies that further promoted space charge separation. The optimised ternary photocatalyst displayed 2314 μmol/g/h H2 generation and 1700 μM/g/h H2O2 production which are 12–86 and 11–27 times higher than the pure materials, respectively. Band position assessment and radical trapping study suggested the occurrence of a dual S-scheme charge transfer mechanism that rationally accounted for the improved photocatalytic performance. A novel CeVO4/Bi/Bi2MoO6 ternary heterostructure was fabricated by in situ deposition of CeVO4 over one-pot-synthesized Bi/Bi2MoO6 binary composite. The effect of the salt precursor and reaction duration on the morphology and crystal structure of Bi/Bi2MoO6 was studied in detail. The initial formation of Bi2MoO6 nanoplates and their subsequent disintegration to nanorods upon prolonged reaction time was observed due to concurrent leaching and reduction of Bi3+ ions to plasmonic Bi0 metal. The CeVO4/Bi/Bi2MoO6 ternary heterostructure demonstrated a uniform deposition of CeVO4 nanoparticles (10–20 nm) over Bi2MoO6 nanorods that are embedded with ultrasmall Bi0 nanodots (2–5 nm). The ternary composites displayed improved optoelectronic features which have been ascribed to the creation of surface oxygen vacancies and plasmonic nature of Bi nanodots. The optimized ternary photocatalyst exhibited encouraging photocatalytic activity for H2O2 generation (953 μM/g/h) and NH4+ production (131 μmol/g/h) with reaction kinetics 7–20 and 4–5 times greater than those of pure semiconductors and CeVO4/Bi2MoO6 binary heterostructure. Based on experimental evidences, a switching of charge migration route from Type-I in CeVO4/Bi2MoO6 to Bi0-mediated all-solid-state Z-scheme for the CeVO4/Bi/Bi2MoO6 composite is proposed, which accounted for its improved photocatalytic activity
Design and Analysis of Multi-User VLC System Under Mobile Environment
No full textOptical wireless communication (OWC) has enormous potential to support massive data transmission requirements. In an indoor environment, OWC with short-range communication is known as visible light communication (VLC) in the literature. VLC is used for indoor lightening as well as communication. VLC is one of the green technologies with unlicensed spectrum, high security, high speed, no health hazards, low cost, and provides ease of installation. These attractive features of VLC provide a viable solution to the last-mile problem in broadband wireless transmission for indoor communication. Despite many advantages, the VLC system remains sensitive to indoor environmental conditions, the distance between the transceiver, field of view (FoV), mobile users, etc. The VLC system design must consider the above channel impairments for reliable communication. This research work focuses on designing a reliable and available VLC system under different channel conditions. Approaches adopted for the design of a VLC system are enumerated below: • Performance of indoor VLC system is significantly influenced by two key factors channel parameters (i.e., transceiver distance, field of view (FoV), and other noise levels) and indoor environmental parameters (i.e., ambient noise). Most of the research work doesn’t account for both parameter. This chapter presents a comprehensive analysis of the VLC system under each of the impairments and interdependencies, which affect the overall functionality. Impact of ambient noise due to various lighting sources has a higher effect on the system performance. Also, the intensity of ambient noise levels depends on the transceiver distance. This study provides a key insights into the VLC system design for dynamic indoor environments. In addition, an experimental testbed is also designed and implemented to evaluate the performance for different channel and environmental parameters. An image is transmitted under different ambient sources under different transceiver distances. A higher PSNR is achieved under low ambient noise while PSNR varied considerably under different strengths of ambient noise sources. • VLC system performance can be improved under channel and environmental parameters by adopting a robust modulation scheme and a power domain scheme. Different modulation schemes (PAM, PPM, QAM, O-OFDM) are evaluated to analyze VLC system performance, with O-OFDM outperforming the state of the art in terms of BER. Also, a multi-user scenario for seamless connectivity and overcome the channel impairments. Power-domain approaches prove to be more effective. A novel ACO-OFDM NOMA is proposed for a multi-user environment under the impact of ambient noise and transceiver distance. The proposed integration facilitates a practical power domain analysis within the NOMA framework that enhances spectral efficiency for both direct LoS and indirect NLoS links. A simulation evaluates the performance of the proposed ACO-OFDM NOMA VLC system, and achieves a high data rate with enhanced spectral efficiency, demonstrating its effectiveness. • In addition, the effect of ambient light on channel properties, considered as noise levels and transceiver distance, becomes critical in a mobile user environment. A statistical model is formulated to depict intensity fluctuations for static and mobile users. Traditional channel estimation methods experience degradation in performance within high-mobility environments. To address this, indoor channel responses within a scattered indoor mobile environment are derived by employing basis functions. A novel technique for channel estimation for mobile channels tailored explicitly for the ACO-OFDM VLC system is introduced. Employing the BEM model, the VLC channel is modeled in both frequency and time domains, encompassing LoS and NLoS communication scenarios. A comprehensive simulations are conducted, integrating both frequency and time domain aspects of an ACO-OFDM VLC system with BEM-based time-varying channel modeling. Finally, the BER for the system model and the corresponding MSE for channel estimation are evaluated and compared with the ideal approaches. • In high-mobility environments, where the variations due to multipath effects are significant, the ACO-OTFS VLC system demonstrates superior performance compared to ACO-OFDM. The VLC channel estimation focuses primarily on establishing communication in a single input single output (SISO) within the ACO-OFDM system. Introducing a novel approach, a multi-user channel estimation method is devised to accommodate the rapid variations in the VLC channel using asymmetrically clipped optical orthogonal time-frequency space (ACO-OTFS). Additionally, this method provides a comparative analysis between BEM-based ACO-OFDM and ACO-OTFS VLC systems. The proposed method extensively analyzes the estimation performance for O-OFDM and ACO-OTFS for the VLC system in fast time-varying channel. Furthermore, a comparative analysis of MIMO frameworks highlights the advantages of the proposed MIMO ACO-OTFS system, which achieves significant BER reduction at lower SNRs compared to MIMO ACO-OFDM i.e., delivering a lower BER of an 8 dB compared to ACO-OFDM
Elucidating the Berberine-Induced Epigenetic Regulation of Nrf2 Signaling Axis and Its Targeted Delivery via Folate- Functionalized Bovine Serum Albumin Nanocarriers Against Glioblastoma
No full textGlioblastoma multiforme (GBM) is recognized as one of the most aggressive and fatal forms of brain cancer, characterized by rapid proliferation, invasive nature, and a poor prognosis. The conventional treatment typically encompasses a combination of surgical resection, radiotherapy, and subsequent chemotherapy using primarily temozolomide. Therapeutic resistance and limited treatment efficacy highlight the need for alternatives, with natural phytochemicals showing promise for their anti-cancer properties. Among phytochemicals, berberine (BER), a naturally occurring isoquinoline alkaloid, has exhibited considerable anti-cancer activity. Our study demonstrates that berberine’s mode of action involves multiple pathways, including triggering apoptosis, inhibiting cel migration, inducing cell cycle arrest, and causing DNA damage, which is primarily mediated through mitochondrial dysfunction facilitated by reactive oxygen species generation. Further, it was found that berberine downregulates the Nrf2 antioxidant signaling pathway in GBM cells. The mechanistic analysis reveals that berberine decreases the expression of KDM6B, resulting in an increased occupancy of H3K27me3 at the Nrf2 promoter, suppressing downstream signaling of the Nrf2 pathway. These findings highlight berberine's potential to promote ROS-mediated cell death and inhibit metastasis- associated pathways, establishing it as a promising therapeutic candidate for GBM treatment. Although berberine exhibits notable anti-cancer potential, its clinical application is significantly constrained by limited solubility, rapid metabolic degradation, and poor bioavailability. A novel drug delivery system employing bovine serum albumin nanoparticles (BSA NPs) was developed to encapsulate berberine, improving its stability and bioavailability. The FESEM and TEM analysis of these BER-BSA NPs revealed a spherical morphology, and further characterizations indicated the successful encapsulation of berberine within the BSA matrix. Hemocompatibility assays confirmed the formulation's biocompatibility, exhibiting no adverse responses with blood components, while in vitro release studies revealed a sustained drug release profile, ensuring gradual release of BER over time. Further, in vitro cell culture evaluations in LN229 cells indicated that BER-BSA NPs produced more significant cytotoxic effects than free berberine, suggesting that the nanoparticle formulation enhances the therapeutic potency of berberine. Additionally, enhanced inhibition of cell migration, increased apoptosis, nuclear condensation, reduction of mitochondrial membrane potential, and elevated ROS production were observed. To enhance the glioblastoma-specific targeting capability of the Sayantan Ghosh (519LS1009), Ph.D. Thesis, NIT Rourkela delivery system, folic acid (FA) was conjugated to BSA nanoparticles, taking advantage of the overexpression of folate receptors in glioblastoma cells. The resulting folate-conjugated nanoparticles (FA-BER-BSA NPs) maintained a spherical shape, and the successful conjugation of folic acid to BER-BSA NPs was validated through FTIR and UV-Vis spectroscopy, with XRD and DSC confirming their amorphous nature. The in vitro evaluations on LN229 cells showed that these FA-BER-BSA NPs possessed superiorcytotoxic effects compared to their non-targeted ones. The enhanced cytotoxicity was further corroborated with enhanced inhibition of cell migration, nuclear condensation, ROS generation, mitochondrial membrane damage, apoptosis induction, and cell cycle arrest. Subsequently, enhanced cellular uptake of FA-BER-BSA NPs was evidenced by fluorescence microscopy and flow cytometry analysis conducted with LN229 monolayers and three-dimensional tumor spheroids. The study demonstrates the efficacy and safety of FA-BER-BSA nanoparticles as a targeted drug delivery system, combining folic acid’s precision targeting with berberine’s anti-cancer activity, offering a promising approach for glioblastoma treatment in precision oncology
Vicinal Diols as C2 Precursor in N & O- Containing Heteroaryl Synthesis
No full textVicinal diols exhibit a unique combination of properties, including high reactivity, selective oxidation, chiral recognition, hydrophilicity, and biodegradability, making them valuable in various fields. Their versatility in synthesis, biological relevance, pharmaceutical importance, and environmental applications make them useful in multiple industries. Specifically, vicinal diols are employed as anti-corrosion agents, lubricants, surfactants, fragrances and flavors, and agrochemicals. Aliphatic vicinal diols play a crucial role in cellular signaling, metabolism, and antioxidant mechanisms, inhibiting glycosidases and regulating carbohydrate metabolism, while also enhancing adhesive properties and coating durability. Furthermore, aliphatic vicinal diols serve as precursors for polyurethanes, polyesters, and epoxy resins, aid in degrading pollutants like pesticides and heavy metals, and facilitate the synthesis of functionalized nanomaterials. In pharmaceutical applications, aliphatic vicinal diols act as versatile intermediates in organic synthesis, enabling asymmetric synthesis and supporting the design and development of new drugs, including antibiotics, antivirals, and anticancer agents. Oxygen and nitrogen- containing heteroaryl compounds are indispensable in various fields due to their unique properties, including high electron affinity, conductivity, photoluminescence, biocompatibility, and stability. Their biological activity, versatility in synthesis, industrial utility, and pharmaceutical importance make them highly sought after. These compounds play a vital role in pharmaceuticals as antibiotics (quinolones, macrolides), antivirals (HIV, hepatitis), anticancer agents (kinase inhibitors), anti-inflammatory agents, and CNS active compounds (anxiolytics, antidepressants). Additionally, they are utilized in agrochemicals as herbicides (pyridines, quinolines), insecticides (neonicotinoids), and fungicides (azoles). In materials science, heteroaryls are employed as conductive polymers (polythiophenes), organic light-emitting diodes (OLEDs), organic photovoltaics (OPVs), and fuel cells. They also find applications in biotechnology such as DNA-binding agents, RNA-targeting compounds, gene delivery systems, and biosensors. Furthermore, heteroaryls participate in asymmetric catalysis, oxidation, and reduction reactions and serve as starting materials in complex molecule synthesis. Some heteroaryl compounds include indole, furan, pyrrole, pyridines, quinolines, isoquinolines, pyrazines, oxazoles, thiazoles, imidazoles, pyrazole and triazoles. In this thesis our objective is to synthesize heteroaryl compounds utilizing vicinal diol as a C2 building block. Chapter 1. Vicinal diols in organic synthesis: A brief review This chapter summarizes the significance and synthetic utility of vicinal diols in heterocyclic chemistry. Vicinal diols possess unique attributes, making them valuable across various disciplines. They serve as anti-corrosion agents, lubricants, and surfactants, and as precursors for polyurethanes and epoxy resins. Vicinal diols find applications in polymer synthesis, as protecting groups, and as a C2 precursor for heterocyclic synthesis, including indoles, pyrroles, imidazolones, pyrazines, piperazines, quinoxalines, and quinolines. Chapter 2. Oxidative coupling of vicinal diols and 2-amino-1,4-naphthoquinone for the synthesis of pyrrolonaphthoquinones An iron-catalyzed oxidative coupling reaction between 1,2-diols and 2- aminonaphthoquinones has been developed, facilitating the regioselective production of benzo[f]indole-4,9-diones under mild conditions. This efficient process involves the oxidation of vicinal diols to α-hydroxy carbonyl compounds, followed by concurrent N-C and C-C bond formation. with 2-amino naphthoquinone. Chapter 3. Access to 2,3-unsubstituted imidazo[2,1-b][1,3]benzothiazole using ethylene glycol as a C2 precursor and subsequent regioselective C3 functionalization Synthesis of imidazo[2,1-b [1,3]benzothiazoles by oxidative coupling of 2- aminobenzothiazoles with vicinal diol was reported. Expectedly, a combination of potassium persulfate and TEMPO oxidized ethylene glycol to α-hydroxy acetaldehyde, which coupled with 2-aminobenzothiazole to afford 2,3- nsubstituted imidazo[2,1- b][1,3]benzothiazoles. The later was exploited as a reliable handle to access 3-substituted imidazo[2,1-b][1,3]benzothiazoles regioselectively Chapter 4. Transition-metal-free access to substituted furans and pyrroles using vicinal diol as C2-precursor A transition metal-free oxidative method to synthesize substituted furans from β- ketoanilides and vicinal diols was reported. This approach accommodates a wide range of functional groups (e.g., halogens, methoxy, methyl, nitro) and enables the regioselective formation of 2,3-disubstituted and 2,3,5-trisubstituted furans via base-promoted oxidative C-C and C-O bond formation. Additionally, substituted pyrroles were synthesized regioselectively using β-ketoenamines, and vicinal diols as C2 precursors. Chapter 5. Vicinal diols as C2 precursor in oxidative ring annulation to form fused Furans This phapter describes a novel synthetic pathway for the metal-free acid-catalyzed oxidative ring annulation of vicinal diols with beta-naphthols, yielding naphtho[2,1- b]furans. Additionally, we successfully applied this catalytic system to achieve a one-pot synthesis of avicequinone B from 2-hydroxy naphthoquinone, resulting in a remarkable yield. The presented methodology offers a convenient and efficient metal-free synthetic pathway for the preparation of diverse biologically active organic compounds
Buckling and Free Vibration of Doubly Curved Sandwich Shells with Viscoelastic Core and Functionally Graded Material Constraining Layer
No full textVibration is one of the primary causes of failure and underperformance in a wide range of structures, machineries and machine components belonging to aerospace, defence and mechanical engineering-based industries. Vibration can affect these structures in different ways ranging from mild inaccuracy in operating performance to catastrophic failure depending on its severity. Periodic loads are also dangerous for the structures prone to bend or buckle under their normal operating conditions. Therefore, detailed understanding about the vibration and buckling characteristics of such structures is very important to prevent any danger or failure in their operations. Based on these observations, the current research presented in this dissertation is primarily focused on the buckling and free vibration of doubly curved sandwich shells with viscoelastic core and functionally graded material constraining layer. Plates and shells are the primary building blocks of almost all types of major structural components in the mechanical and civil engineering domain. The primary motive to conduct research on the sandwich doubly curved shell panels is their excellent structural characteristics and their versatility to be modified by changing the layer properties of the sandwich based on the application. The sandwich shell addressed in the present research comprises of three layers. The base layer is made up of isotropic elastic material core of soft viscoelastic material and the constraining top layer is made up of metal-ceramic functionally graded material (FGM). Due to the excellent characteristics of viscoelastic materials and FGMs respectively in vibration suppression and providing additional strength and stability to the structure, the preset sandwich structure can be a better choice compared to their conventional counterparts. The mathematical modeling of the present sandwich shell panel is done using an eight noded isoparametric finite sandwich shell element based on the first order shear deformation theory (FOSDT). The governing equations of motion have been derived using finite element method in conjunction with the Hamilton’s energy principle. This dissertation is primarily subdivided into four technical sections which are dedicated to the investigation of buckling and vibration behavior of the current sandwich shell panel under different support and loading conditions as well as environments of engineering importance. A detailed parametric study has been conducted in each section to show the influence of critical system parameters on the buckling and free vibration behavior of the sandwich shell panel. Free vibration and buckling of viscoelastic-FGM doubly curved sandwich shell panels under different boundary conditions along with a detailed parametric study is conducted. The critical observations reveals that all sides clamped (CCCC) boundary condition imparts additional strength and stiffness to the structure compared to other boundary conditions. This eventually results in the increased natural frequencies and critical buckling loads of the structure. At the same time, modal loss factors of the structure have been observed to be decreased. Also, the elliptical paraboloid shell geometry is observed to have increased natural frequencies in many instances compared to the other shell geometries reported. Influence of high temperature environment on the free vibration and buckling behavior of viscoelastic-FGM doubly curved sandwich shell panels is investigated. As evident that increased temperatures are prone to negatively influence the strength and stiffness of many metallic structures, the same has been also observed in the current findings. However, due to the unique characteristics of the different layers of present sandwich shell panels, the influence of high temperature doesn’t seem to be that significant as it could be with the conventional metallic structures. Still, a considerable reduction in the modal natural frequencies as well as critical buckling loads of the structure has been observed majorly. The investigations of free vibration and buckling behavior of viscoelastic-FGM doubly curved skewed sandwich shell panels reveal that the skewness of the panel plays an important role in its structural behavior. Based on the observations, an increase in the skew angle results in the increased natural frequencies as well as critical buckling loads of the structures with negligible influence on the modal loss factor of the system in majority of the findings. Investigations of the buckling and free vibration characteristics of viscoelastic-FGM doubly curved sandwich shell panels resting on two parameter elastic foundations suggests that both the Winkler’s as well as the shear foundation parameters when increased are responsible in increasing the modal natural frequencies and the critical buckling loads of the structures, whereas, slightly decreases the system modal loss factors on the other hand. However, the shear foundation parameter is observed to be more dominant than the Winkle’s parameters in influencing the structural behavior of the present structure
Ultrasonic Vibration Assisted Turning of Inconel 825: Tool Design, Experimental Investigations and Numerical Modelling
No full textThe growing emphasis on sustainable and environmentally friendly manufacturing practices has led to the development and adoption of various advanced machining techniques. Ultrasonic Vibration Assisted Turning (UVAT) stands out as a promising technology in this context due to its ability to enhance machining performance while reducing the environmental impact. Inconel 825 is a nickel-based superalloy with excellent corrosion resistance, especially in highly acidic environments. It is often used in chemical processing, pollution control, oil and gas exploration, and marine environments. However, its unique material properties, including high strength, low thermal conductivity, and high work-hardening rates, make it tough to machine conventionally. So, an experimental study has been carried out considering UVAT as a clean manufacturing process, emphasizing its benefits, underlying mechanisms, and potential for widespread industrial application by performing dry turning on Inconel 825 through UVAT. Here 20 kHz ultrasonic vibrational frequency and small amplitude is applied to tool to remove material by intermittent cutting. The present work is classified into three sections (i) Design and fabrication of flexible UVAT-tool using Ansys v18® FEM analysis (modal and harmonic) using SS304 (ii) Experimental investigation of both CT and UVAT considering uncoated and multilayer coated tool inserts (iii) Numerical modelling through Deform 3D® v10.2 and validate with experimental results. UVAT showed significant reductions in cutting forces and tool-tip temperature with improved surface finish of the workpiece. The influence of multilayer coating in PVD coated TiAlN+TiAlCrN WC insert over monolayer TiAlN-WC and uncoated WC insert have been obtained. Finally, machinability indices like chip morphology, surface integrity, and tool wear were observed. The results confirm the suitability and advantages of the environment friendly dry UVAT process compared to the CT process to machine hard to cut metal Inconel 825