http://localhost:8081/jspui/handle/123456789/4966 Tue, 01 Jul 2025 16:26:41 GMT 2025-07-01T16:26:41Z http://localhost:8081/jspui/handle/123456789/15605 Title: STUDY OF AlN/FSMA MAGNETOELECTRIC HETEROSTRUCTURE FOR MEMS APPLICATIONS Authors: Pawar, Shuvam Abstract: In the current era, the progress of electronic technology is directly coupled with the advancement made in materials science. Magnetoelectric materials are the potential candidate for several multifunctional devices such as magnetic random-access memory, switches, magnetic sensors and tunable resonators. In these kinds of composites, the Magnetoelectric (ME) response is a product tensor property, i.e., outcome of the mechanical interaction between the magnetostrictive effect (magnetic/mechanical effect) occurring in the magnetic phase and the piezoelectric effect (mechanical/electrical effect) present in the piezoelectric phase. The ME coupling is observed in diverse structures such as bulk ceramic, two and three-phase ME composites and nanostructured thin films. However, the ME composite thin films have attracted enormous attention because different phases can be attached and designed at the atomic level with higher precision and sharp interface. Furthermore, nanostructured thin film composites enable the researchers to investigate the physical cause of the ME coupling effect at the nanoscale level. The strength of the ME coupling depends on many factors, such as interface quality, high anisotropy magnetostriction, lattice mismatching, and functional characteristics of the individual piezoelectric and magnetostrictive layers. The ideal candidates for magnetostrictive and piezoelectric layers are ferromagnetic shape memory alloys (like-NiMnIn, NiMnSb, etc.) and AlN, respectively. Ferromagnetic shape memory alloys (FSMAs) exhibit a large applied magnetic field and temperature induced strain in the temperature region during the martensite to austenite phase transition as compared to leading magnetostrictive materials such as Trefnol-D and metglas. The NiMnIn exhibits giant magnetostriction coefficient at room temperature with multiple degrees of freedom to tune its magnetostriction, i.e., by varying temperature, magnetic field, stress. On the other hand, Aluminium Nitride (AlN) is a lead-free complementary metaloxide- semiconductor (CMOS) compatible piezoelectric material with a high value of voltage piezoelectric coefficient (e33). The deposition process of AlN is also well reproducible, and its chemical compatibility is well suited with semiconductor fabrication technology. For strong coupling between ferromagnetic and piezoelectric layers in the artificial magnetoelectric heterostructure, it is desirable to fabricate high-quality thin films with a sharp interface that can be attained by several growth techniques such as molecular beam epitaxy, pulsed laser deposition, metal oxide chemical vapor deposition, sputtering. Thu, 01 Oct 2020 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/15605 2020-10-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/15558 Title: CARBON NANOFILLERS BASED THIN FILMS FOR TOXIC GAS SENSOR APPLICATIONS Authors: Bag, Souvik Abstract: There are various kinds of natural, chemical and artificial species available in our surrounding environment, some of them are very essential while others are more harmful or less. The essential gases/species like oxygen (O2), nitrogen (N2) and humidity should be maintained at sufficient level in global atmosphere while excess emission of hazardous or toxic gases can harm living atmosphere. In this regard, burning of fossil fuels (e.g. Coal, petroleum, and natural gas) is a major concern for global air pollution [1-3]. On burning, compounds containing carbon, nitrogen, and sulfur generate gaseous oxides by reacting with air. These toxic gases are harmful in living atmosphere in parts per million (ppm) or even parts per billion (ppb). Among these gases, increase emission of carbon dioxide (CO2) and other greenhouse gases since the mid-20th century has been thought to be the cause of the increase in the average near-surface air and ocean temperature of the earth, a phenomenon known as global warming. In particular, CO2 detection in ambient air has continued to be a challenge due to oxidizing stability of the compound and interferences from several species, such as nitrogen dioxide (N2O) and carbon monoxide (CO). In many fields, such as industrial emission control, household security, and vehicle emission control, monitoring of CO2 is mandatory. Further, a CO2 sensor can be greatly beneficial to a wide range of applications, including breath and blood analysis for medical diagnosis [4-6], portable gas detector for personal protection and gas monitoring for climate control [7]. In view of safety regulation, a confined workplace should have CO2 concentration level below 5000 ppm in 8 h average; even lower concentration can cause discomfort, headache, respiratory problem, and other sensitive health issues [8-9]. In related to various chemical compounds, volatile organic compounds (VOCs) also attract much more interest from the last few decades in abundant significant fields like R&D laboratories, industrial productions etc. due to its toxicity, flammability, environmentally hazardousness, and explosiveness [10-11]. So, a rapid detection of VOCs is desired to maintain their concentration within permissible limit and avoid exposure associated health hazards. Chronic exposure of VOCs such as benzene, toluene, ethyl benzene and methanol poses serious health concerns such as skin and sensory irritation, carcinogenesis, mutagenesis, central nervous system depression and respiratory system damage [12-13]. Among VOCs, methanol (MeOH) has been used as an important raw chemicals in various industries as well as household products (drugs, perfumes, colors, dyes, antifreeze, etc) [14]. It is also a valuable alternative automobile fuel as it has already been used for fuel motor vehicles in many 2 countries [14]. On the other hand, methanol has also been strongly injurious to human health as well as environment monitoring due to its toxicity, flammability etc. [15-16]. Inhalation of ~20 mL methanol can lead to blindness, while ~60 mL may cause to fatal accident, if not immediately treated. Hence, early detection of methanol vapor makes a high demand for safety purpose. Though many researchers have developed low power consuming CO2 as well as methanol sensor with remarkable sensitivity, stability and selectivity [16-19] but, still there is a demand due to high sensitivity, small in size, low cost, and modest operation at room temperature. Even, development of CO2 sensor operating at room temperature under different humid condition makes another challenge. Wed, 01 May 2019 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/15558 2019-05-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/15463 Title: POLY(AMIDOAMINE) DENDRIMER BASED NANOMATERIALS FOR DELIVERY OF ANTICANCER AGENTS Authors: Matai, Ishita Abstract: Cancer is still notorious to create havoc in the modern society despite considerable advancements in field of medical technology. Though commendable efforts and improvements have been done to better the lives of cancer patients, still the ultimate goal to eradicate this dreadful disease demands inspection of new smart materials. In this light towards cancer. nanotechnologv based materials are certainly valuable. Lately, polymer based nanoscale drug delivery systems (l)l)S) as nanomedicincs' have garnered much attention for the chernotherapeutic drug delivery in cancer treatment. With a suitable design and structural versatility, they provide biocompatibility. controlled drug release profiles, and increased drug circulation times. Such advantages suggest the pre-eminence of nanoscale drug carriers over traditional drugs. Among the available polymers, dendrimers especially poly(amido amine) (PAMAM) dcndrimcrs oiler numerous advantages such as distinct molecular architecture, monodispersity, enhanced solubility of hydrophobic drugs, reduced toxicity and tumor selectivity by enhanced permeability and retention (EPR) effects. Therefore, the present thesis is an endeavour to develop dendrimer based nanornaterials as delivery systems for anticancer agents. With this perspective, PAMAM dendrimer based multicomponent therapeutic agents have been developed for in vitro cancer therapy applications. Firstly. G5.0 PAMAM dendrimers stabilizing silver nanoparticle surface (I)sAgNPs) were synthesized to encapsulate anticancer drug 5-fluorouracil (5-FLJ) to attain anticancer synergism. The formation of 5-hti loaded l)sAg nanocomposites (5-FVZiI)sAgNCs) was confirmed by various characterization techniques. l'hesc NCs were taken up elThctivety by cells and elicited synergistic antiprolilerative effects in A549 (human lung cancer) and MCF-7 (human breast cancer) cells at low doses. When the therapeutic outcomes were investigated in detail by diffarent cell-based experiments. 5_lU)DsAgNCs induced apoptosis in cancer cells. The therapeutic effects of 5-FU1)sAgNCs were more pronounced in MCF-7, when compared to A549 cells. Another smart dendrimer nanoformulation i.e. chemically cross-linked nanogels ofG5 PAMAM dendrimers and sodium alginate (AG) have been prepared as delivery systems. Ihe integration of PAMAM dendrimer with alginate and formation of AG-G5 hybrid nanogels as confirmed by different microscopic and spectroscopic techniques. Chemo-drug epiruhicin Fl>l) was entrapped in the nanogels interiors. When evaluated in vitro, these nanogels released FPl siowl w and steadily in tumor environment. Fluorescence imaging, study of nuclear and morphological deformations in EPlcAG-G5 nanogels treated MCF-7 indicated apoptosis induction and subsequently cell death. Subsequently. the impact of hydrophobic modification of' G5 1AMAM dendrimer surface on delivery of' anticancer agents has been studied. Lipid-like myristic acid (My) chains were introduced on the dendrimer surface, to augment the delivery profile of anti-estrogen tamoxilen [AM) in MCF-7 (ER+) cells. The successful grafting of My chains on PAMAM dendrimers (My-g-(35) and formation of My-g-GSITAM nanocomplexes was confirmed with several characterization experiments. This dendrimer nanoformulation of TAM demonstrated good water-solubi lity. stability and cell death inducing ability. Finally, the theranostic (therapeutic and diagnostic) applications of partially surface acetylated (15 PAMAM dendrimers towards cancer therapy have been elucidated. Luminescent carbon dots (CQDs) with anionic terminus and cationic acetylated G5 IAMAM dendrimers were combined to form self-assembled fluorescent hybrids. The fluorescence of CQDs in hybrids was enhanced in the vicinity of primary amine groups of dendrimers. making them suitable as cellular imaging probes. When EPI was entrapped in the dendritic architecture. CQDs@,EPlcG5_Ac85 hybrids demonstrated anticancer potential. Moreover, these hybrids served as a dual-emission delivery system to track the intracellular distribution and cytotoxic effects of Eli. Further in vifro assays implicate apoptosis induction in hybrid treated MCF-cells. In a nutshell, different IAMAM dendrimer based nanomaterials are presented as nanomedicines to efficaciously deliver various anticancer agents especially to breast cancer cells to inhibit their proliferation and induce cell death. Sun, 01 May 2016 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/15463 2016-05-01T00:00:00Z http://localhost:8081/jspui/handle/123456789/14895 Title: USE OF CARBON BASED NANOFILLERS FOR ENERGY HARVESTING APPLICATIONS Authors: Kaur, Navjot Abstract: Energy is the essential requirement for today’s life. Due to the diminution of the energy sources, it is necessary develop devices that can harvest the wasted/unused energy that exists in the ambient environment. To address this, triboelectric nanogenerators (TENGs) have been developed as an innovative paradigm for energy harvesting. TENG is a device that can harvest mechanical energy present in the surrounding environment into electrical energy by the combination of triboelectric and electrostatic induction effect. The electrical outputs obtained from TENGs depend on the friction of materials that are selected from the triboelectric series on the basis of their triboelectro-negativity and triboelectro-positivity. So, in this regard, we have selected aluminum and nylon 6,6 as triboelectro-positive materials and polyvinylidene fluoride (PVDF) as electronegative material, according to triboelectric series. In order to enhance the electronegativity of the PVDF polymer, we incorporated the carbon based nanofillers like reduced graphene oxide nanoribbons (rGONRs) and fluorinated-graphene nanoribbons (F-GNRs), which contain various functional groups such as as hydroxyl (-OH), carboxyl (-COOH), epoxy (C-O-C) and fluorine (-F), which will improve the electronegativity of the resultant materials. So, we have synthesized rGONRs through unzipping of MWCNTs and F-GNRs via chemical modification (i.e. functionalization) of rGONRs. Moreover, we have fabricated the nanofibers of nylon 6,6, PVDF and PVDF/F-GNRs composite via electro-spinning technique. These synthesized materials are examined using various characterization techniques such as X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, Atomic force microscopy (AFM) and Fourier Transformation Infrared spectrophotometer (FTIR). In this dissertation work, we have reported the comprehensive review on the triboelectric nanogenerator (TENG), fabrication of an arc-shaped single electrode mode based TENG and vertical contact-separation mode based TENG. The arch-shaped single electrode based TENG was fabricated using rGONRs/PVDF thin film act as a triboelectro-negative and aluminum would act as a triboelectro-positive material, which effectively convert mechanical energy into electrical energy. The incorporation of rGONRs in PVDF polymer enhances average surface roughness of rGONRs/PVDF thin film. With the combination of the enhancement of average viii | P a g e roughness and presence of various functional groups, which indicate improvement in charge trapping capacity of prepared film. The output performance was discussed experimentally as well as theoretically. The maximum peak voltage was found to be 0.35V. The newly designed TENG to harvest mechanical energy and opens up many new avenues of research in the energy harvesting applications. In the vertical contact–separation mode based TENG using electrospun PVDF/F-GNRs and nylon nanofibers as triboelectro-negative and triboelectro-positive materials, respectively. The fabricated nanofibers were characterized and further used in the fabrication of TENG. The obtained maximum open-circuit voltage and short-circuit current are found to be 4.59 V and 98 nA, respectively, at the maximum force of 260 N. Moreover, electrical charge (Q) after 4.52 sec is examined to be 443 nC. The fabricated TENG is stable up to 2,000 cycles without any drop in output performance and also nanostructures are not get damaged. If the generated electrical output is stored in the rechargeable battery, then it could be used to drive various portable electronic devices. Fri, 01 Mar 2019 00:00:00 GMT http://localhost:8081/jspui/handle/123456789/14895 2019-03-01T00:00:00Z