Theses (Faculty of Science and Technology)
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A DE Természettudományi és Technológiai Kar Tanácsának 2009. november 25.-i határozata alapján a jövőben elektronikus formában is elhelyezésre kerülnek a szakdolgozatok a Debreceni Egyetem Egyetemi és Nemzeti Könyvtár által működtetett egyetemi archívumban, a DEAba. A szakdolgozatok az archívumból kizárólag a Debreceni Egyetem IP-címeiről hozzáférhetőek, azokat nem lehet kinyomtatni, és azokból szövegrészeket nem lehet kiemelni.
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Megjelenítve 1 - 20 (Összesen 655)
Tétel Korlátozottan hozzáférhető Development of a LoRa-based data acquisition system for health monitoringAgha, Chukwumela; Harasztosi , Lajos; DE--Természettudományi és Technológiai Kar--Fizikai IntézetThis thesis focuses on the realization of a LoRa-based data acquisition system intended for health monitoring. The project establishes a Point to Point (P2P) communication model. The system employs a temperature sensor for data acquisition to enable wireless transmission of data over long distances with less power requirements. An example of how the system works in health monitoring situations is provided by the alert mechanism that activates in case of temperature changes. The components involved include PCBs, software that provides interaction between the components and the display of data. The thesis focuses on the ability of LoRa P2P systems to deliver an efficient, reliable and affordable way of implementing healthcare solutions for remote patient monitoring.Tétel Korlátozottan hozzáférhető 15-membered rigid macrocyclic ligand for Mn2+ complexation: synthesis and coordination chemical characterizationBaghirova, Aghanana; Tircsó, Gyula; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThe investigation of Mn²⁺ chelates as alternatives to Gd³⁺-based MRI contrast agents has gained significant attention due to their promising safety and performance profiles. My research focused on the synthesis and coordination chemistry of a novel 15-membered bipyridine-based macrocyclic ligand, 15-BPyN5. The ligand demonstrated excellent thermodynamic stability (log K_MnL = 13.44), high kinetic inertness, and favorable relaxivity properties (r1p/r2p = 3.60/6.60 mM⁻¹s⁻¹). Dissociation studies revealed slow exchange kinetics with Zn²⁺ ions, with half-lives of 79.0 and 28.7 hours at 25°C and 37°C, respectively, attributed to the rigid coordination environment provided by the bipyridine moiety. These properties highlight the potential of [Mn(15-BPyN5)] as a safe and effective MRI contrast agent. This work paves the way for developing non-toxic alternatives to gadolinium-based agents, offering improved safety and imaging performance.Tétel Korlátozottan hozzáférhető DEVELOPMENT OF A SYSTEM FOR BATTERY CELL TESTINGA.A. Lulu, Ali; Harasztosi, Lajos; DE--Természettudományi és Technológiai Kar--Fizikai IntézetThis Thesis focuses on the development and optimization of a testing system for battery cells, while focusing on LIBs due to their daily uses in our modern society and time, the key challenges and features in the performance, safety, and life span can be addressed through the design of a testing system. The Development of battery cell testing offers a way to safely test the performance of the lithium-ion batteries very effectively and easily. It also focuses on the process of creating a PCB design in which it Charges the Lithium-ion battery at a constant current, and how does it discharge it at a constant current. It describes the difference between an old battery and a new lithium ion battery in there capacity, voltage rise, voltage drop, ,the time for them to fully charge, and state of charge. The document expresses the importance of how to optimize the battery and how to safely test the lithium-ion battery.Tétel Korlátozottan hozzáférhető Possibility of Superconducting Technology for Wind Turbine GridsOyeleke, Rebecca; Janos, Arpas Kosa; DE--Természettudományi és Technológiai Kar--Fizikai IntézetThis thesis explores the potential of superconducting technology to revolutionize wind turbine grids by enhancing efficiency, reliability, and energy transmission capacity. By leveraging high-temperature superconductors, the study addresses key challenges such as energy losses in conventional power systems and the integration of renewable energy sources into modern grids. It evaluates the feasibility of superconducting generators, cables, and energy storage solutions in offshore and large-scale wind farms, emphasizing their role in minimizing losses and stabilizing power distribution. The research also examines the economic and technical hurdles, including the cost of materials and the need for advanced cryogenic systems. Ultimately, the thesis underscores the transformative potential of superconductors while highlighting the steps needed to overcome adoption barriers. This work provides valuable insights for advancing sustainable energy technologies in the face of growing global energy demands.Tétel Korlátozottan hozzáférhető New strategy for the synthesis of 2-(N-substituted-amino)-2-deoxy-D-glucono-1,5-lactone arylsemicarbazonesOyun-Erdene, Enkhjin; Sándor, Kun; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThis research focuses on synthesizing selective, and potential inhibitor for O-GlcNAcase (OGA), an enzyme linked to diseases including Alzheimer’s, diabetes and cancer. Based on previous research, this study focuses on the synthesis of 2-(N-substituted-amino)-2-deoxy-D-glucono-1,5-lactone arylsemicarbazones. We have designed and performed a five-step synthesis of 2-(N-2,2,2-trichloroethoxycarbonylamino)-3,4,6-tri-O-acetyl-2-deoxy-D-glucono-1,5-lactone 4-phenylsemicarbazone. After selective cleavage of the Troc group, this compound can be used as a starting material for the preparation of new OGA inhibitors.Tétel Korlátozottan hozzáférhető Machine Learning on MicrocontrollersGerelmaa, Tuguldur; Zilizi, Gyula; DE--Természettudományi és Technológiai Kar--Fizikai IntézetMachine Learning has made remarkable progress in the past decade, but current models are computationally expensive. This thesis focuses on deploying machine learning models on microcontrollers. MobileNet based model was trained for two projects: A person detection model was trained, achieving 78.6% accuracy with 225 KB size and 170 KB RAM usage on an ESP32-CAM board. The board sends detected images to a webserver for further analysis. In an another project, keyword detection model was trained, achieving 91.12% accuracy with 120 KB size and 38 KB RAM usage, deployed on a custom made ESP32-based PCB with a MEMS microphone.Tétel Korlátozottan hozzáférhető [(η⁵-Cp*) Rh]²⁺ Binding strength of an ambidentate metal chelatorKechakmadze, Lizi; Peter , Buglyo; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThe aim of my research work was to carry out NMR and MS measurements using the newly synthesized ImEtHpH ligand to explore its [(η⁵-Cp*)Rh]²+ binding capabilities in an aqueous solution. Shedding light to the donor atom preference of the metal ion might provide valuable information on the forthcoming strategy of the synthesis of the Co/PGM heterobimetallic complexes. I have used NMR and ESI-MS methods during my work. In summary, our results indicate that this ligand also forms mainly (N,N) chelate with the rhodium cation but excess of the metal ion should be avoided when one is about to make the solid complexes. As previous results indicate, the synthesis should be started with the use of the Co(III) entity first that has high preference toward the (O,O) chelating set of these type of ambidentate ligands.Tétel Korlátozottan hozzáférhető Intramolecular domino cyclization of indole derivatives for the preparation of heterocyclic ring systemsDavaadorj , Enkhjin; Király, Sándor Balázs; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThe goal of my thesis was to synthesize indole-based polycyclic structures through intramolecular domino cyclization reactions, focusing on forming condensed heterocycles. I started with N-protected indole derivatives and performed transformations, including reduction, oxidation, reductive amination, and aromatic nucleophilic substitution, to prepare the substrates for domino cyclization. Various active methylene compounds, such as cyclic diketones, pyrones, and acids, were used in the cyclization, yielding seven derivatives of novel condensed O,N-heterocycles via intramolecular HDA reactions. Additionally, acyclic esters, nitriles, and nitro-substituted active methylenes were reacted with the indole substrate, forming three derivatives of polycyclic O,N-heterocycles. The cyclizations were diastereo- and regioselective, with only the ketone carbonyl involved in the IMHDA reaction. Contrary to our expectations, the nitro-substituted active methylene reagents underwent DK-IMHDA cyclization instead of the nitro-HDA pathway. These synthesized compounds are proposed for further biological evaluation, especially for their potential anti-cancer activity, to compare their effectiveness with known benzene-fused analogues.Tétel Korlátozottan hozzáférhető Synthesis and Characterization of Crosslinked Polyimide AerogelsAdemi, Armela; Forgács, Attila; Kalmár, József; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThis thesis details the fabrication and characterization of chemically imidized polyimide aerogels starting from diamines and diacid anhydrides, crosslinked with 1,3,5-benzene tricarbonyl chloride (BTC). Conventional characterization techniques involving Low-Voltage Scanning Electron Microscopy and Fourier-Transform Infrared Spectroscopy were applied to assess their morphology and chemical identity, respectively. Dynamic Mechanical Analysis (DMA) and thermal shrinkage tests were conducted to evaluate the thermal behavior of these materials. Additionally, the electrolyte uptake was tested in mediums of different pH, and Nuclear Magnetic Resonance (NMR) relaxometry studies were performed to gain insight into the hydration mechanism of polyimide aerogels. The focus on thermal and hydration properties is particularly relevant in light of recent advancements, where polyimide aerogels have been proposed as promising alternatives for battery separators, offering improved features of safety and efficiency.Tétel Korlátozottan hozzáférhető Synthesis of unsubstituted benzochalconesAzumah, Emmanuel Mawuli; Kurtán , Tibor; Kónya, Krisztina; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThe antitumor activity of flavones is linked to their capability to target important cellular structures, which results in the arrest of the cell cycle and the induction of apoptosis( the planned death of damaged cells in a body) in tumour cells. Flavonoids, a prominent category of polyphenolic compounds found abundantly in fruits, vegetables, nuts exert their effects by inhibiting a variety of enzymes that are critical to the process of tumorigenesis. In this research work, I look into a way of synthesising a particular type of flavonoids-benzochalcones.Tétel Korlátozottan hozzáférhető APPLICATIONS OF AMPHIPHILIC BLOCK COPOLYMERSEGWELE, MARIA; NAGY, TIBOR; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThis thesis investigates the chemistry, structure, and behavior of amphiphilic block copolymers, emphasizing their applications. It is a type of co-polymer including both hydrophilic and hydrophobic segments. These blocks may autonomously assemble into distinct structures such as micelles and polymerosomes, rendering them valuable in drug delivery, self-assembly, nanotechnology, gene therapy, imaging, diagnostic equipment, and surface functionalization. Amphiphilic block copolymers are essential for colloidal stabilization, ensuring stability and minimizing environmental effect. The research investigates the biodegradability and ecological effects of these materials, the need for surfactants, and the environmental implications of amphiphilic block copolymers. It discusses green chemistry, whereby technologies seek to minimize pollution and promote sustainability via the use of sustainable resources in chemical synthesis.Tétel Korlátozottan hozzáférhető MRI Image Construction based on Fourier TransformationRoy, Anindya; László, Balkay; Cserháti , Csaba; DE--Természettudományi és Technológiai Kar--Fizikai IntézetIn short, the integration and effectiveness of Fourier Transform (FT) techniques in enhancing the quality and efficiency of Magnetic Resonance Imaging (MRI) was studied. Given the dire role of MRI in medical diagnostics, improving image contrast, and reducing artifact presence are paramount for more precise disease diagnosis and treatment monitoring. The research began with a detailed review of the fundamental principles causing both MRI technologies, and the role of Fourier Transformation (FT). Their interdependence was also emphasized. Alongside, the theoretical foundation was explored through a complete literature review, highlighting the recent advancements in MRI imaging techniques. Subsequent experimental analyses engaged MATLAB-based simulations to implement various FT techniques, including the Fast Fourier Transform (FFT). These simulations were designed to assess the effectiveness of FT in improving spatial resolution and signal-to-noise ratios under different imaging conditions. Additionally, practical aspects of FT, such as phase encoding and the handling of noise and signal decay in MRI scans, were examined. For better understanding, diagrams were added throughout the paper. Notable outcomesfrom this research demonstrated that the application of FFT significantly reduced processing times while maintaining high image quality, particularly in dynamic imaging scenarios where speedy data acquisition is necessary. Moreover, texture analysis, which measures various parameters, was discussed, and the analysis was done on the images. Even the graph lines were presented from figures 32 to 37, along with some comments.Tétel Korlátozottan hozzáférhető Analysis of Spectroscopic Optical Measurements on Sensor StructuresAjayi, Ayomide; Petrik, Péter; DE--Természettudományi és Technológiai Kar--Fizikai IntézetThis thesis presents a framework for analyzing spectroscopic optical measurements on sensor structures, specifically plasmonic and porous materials. It addresses the modeling challenges of these materials by applying the Transfer Matrix Method and Effective Medium Approximation to simulate light interactions, enabling precise optical characterization. To optimize parameter extraction and improve computational efficiency and accuracy, various fitting algorithms—including Levenberg-Marquardt, Differential Evolution, and Adaptive Memory Programming for Global Optimization (AMPGO)—are benchmarked. A custom Python-based software tool, incomplete-ease, is developed for streamlined data fitting, visualization, and parallel processing, integrating the models and algorithms for rapid analysis of ellipsometry data. The framework enhances stability and reduces processing time, demonstrating effectiveness across sensor configurations and applications, thus advancing the precision and accessibility of spectroscopic techniques in research and industry.Tétel Korlátozottan hozzáférhető Application of Superconducting Technologies in Protection System for Tajik Hydroelectric Power PlantsSadykov, Sirozhiddin; Kósa, János; DE--Természettudományi és Technológiai Kar--Fizikai IntézetThesis titled "Application of Superconducting Technologies in Protection Systems for Tajik Hydroelectric Power Plants" provides a detailed analysis of hydroelectric power plants and the potential benefits of using superconducting technologies in their protection systems. Particularly, an analysis of hydroelectric power plant facilities in Tajikistan was discussed, as the country has significant hydroelectric potential. Approximately 95% of Tajikistan's electricity is generated by hydroelectric power plants. Thesis outlines the following key aspects: 1. An overview of the operating principles of hydroelectric power plants; 2. Detailed information on Tajikistan's hydro power facilities; 3. An analysis of the distribution grids in Tajikistan; 4. The potential application of superconducting technologies in protection and distribution systems; 5. The design a superconducting protection system for hydroelectric power grids;Tétel Korlátozottan hozzáférhető DESIGN AN SFCL FOR HVDC GRIDDuntow, Khadhar Abdi; Árpád , János Kósa; DE--Természettudományi és Technológiai Kar--Fizikai IntézetThe increasing use of HVDC systems for transmitting power over long distances and incorporating renewable energy sources has made dealing with fault currents a key concern to maintain grid stability and equipment safety. This thesis offers an overview of HVDC power systems by reviewing the existing HVDC system and how it contributed to our energy needs. It gives an in-depth examination of different SFCLs, showcasing their applicability and efficiency in HVDC settings. This paper also discusses HVDC switchgears that contribute towards maintaining a grid system and managing faults effectively. Finally, it focuses on the design of an SFCL specifically for HVDC grid protection, detailing the calculations and specifications needed to achieve effective fault current limitations. This study demonstrates how an SFCL can enhance the safety, resilience, and reliability of HVDC systems, addressing key challenges in modern power infrastructure.Tétel Korlátozottan hozzáférhető Phytolith assemblages in different organs of nine conifer species from the holarctic regionRojas San Martín, Gonzalo; Dr. Lisztes-Szabó , Zsuzsa; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetThe scope of this research is to broaden phytolith analyses in the needles, bark, and cones of nine conifer species common in the Holarctic region: Picea abies, Picea glauca, Pinus cembra, Pinus mugo, Pinus peuce, Pinus nigra, Pinus sylvestris, Picea orientalis, and Taxus baccata. Dry and wet ashing were involved in the process of extracting the phytoliths, after which a light microscope was used to observe these structures, and the ICPN 2.0 was utilized to identify the morphotype. Results showed that blocky-type phytoliths are potential proxies for identifying taxa at the species or genus level. They also indicated regularities in elongate phytoliths depending on the species. Finally, the cones have exhibited dissimilar morphotypes, which may have implications for future phytolith analyses.Tétel Korlátozottan hozzáférhető Glycomimetics and platinum-group metal complexes as potential drugsBaimbetova , Sholpan; Juhászné Tóth, Éva; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThe thesis is a review of novel potential anticancer agents. Glycomimetics are synthetic carbohydrates, that mimics carbohydrates and play a critical role in cancer therapy by acting like inhibitirs, their structural stability and specificity make them promising alternatives to natural glycans in therapeutic applications. Platinum-group metal complexes, including platinum, ruthenium, and iridium compounds, are key components in anticancer drug development due to their ability to induce apoptosis, and overcome resistance in cancer cells. Among these, half-sandwich complexes are particularly notable for their structure, enabling engineering of their properties for enhanced selectivity, reduced toxicity, and improved activity against drug-resistant tumors. These compounds represent a significant advancement in the design of targeted, more effective anticancer treatments. Chemical Glycobiology Research Group of the Organic Chemistry Department of the University of Debrecen synthesized and patented new potential ligands for anticancer chemotherapy.Tétel Korlátozottan hozzáférhető Nickel(II) Complexes of Histidine Containing PeptidesIsmayilov, Eljan; Várnagy, Katalin; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThis thesis aims to examine the interaction of transition metal ions with histidine-containing dipeptides in order to understand how these ions coordinate in metalloenzymes. With a group of researchers from the University of Debrecen we investigate the Tau Protein which is the main component of the intracellular filamentous inclusions that are linked with neurodegenerative diseases. Series of potentiometric and spectroscopic experiments were performed to study the interactions between nickel(II) ions and methionyl-histidine (Met-His) dipeptide in Tau(26-33) – TMHsequence). While the potentiometric experiments will provide information about the thermodynamics of metal-peptide binding, the spectroscopic analysis have yielded useful insights into the coordination geometry and structural data of the formed complexes.Tétel Korlátozottan hozzáférhető Fragmentation of organic molecules under mass spectroscopic conditionsOspanova, Zarema; Nagy, Lajos; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThis study investigates the fragmentation of organic molecules under mass spectrometric conditions with a special focus on the identification of oxidized amino acids in peptide chains. The initial experimental setup involved the use of a mass spectrometer equipped with sodium trifluoroacetate (NaTFA) dissolved in methanol as a solvent. The study examined in detail the fragmentation behavior of the GTHSMKHM peptide with a focus on the oxidation of specific amino acid residues. Oxidized forms were identified by molecular weight analysis using specialized software, confirming the presence of oxidized histidine and its impact on the peptide structure. This research identified that oxidation occurred specifically on the histidine residue. This conclusion was drawn by comparing the MS spectra of the oxidized and non-oxidized oligopeptides.Tétel Korlátozottan hozzáférhető Analysis of key metabolites produced by Lactobacillus plantarum ATCC 14917 strainAnarbayeva, Inessa; Barna, Teréz; DE--Természettudományi és Technológiai Kar--Biotechnológiai IntézetIn this study, Lactobacillus plantarum ATCC 14917 strain was investigated to reveal the extracellular metabolites produced during the fermentation of MRS culture by this strain. In MRS medium glucose is the carbon cource. We divided metabolites to seven compound classes based on functional groups: amino acids, nitrogen-containing compounds (excluding amino acids and nucleotides), carboxylic acids, alcohols, alkaloids, aromatic compounds, and alkanes/alkenes. Results show increased production of bioactive short-chain fatty acids (SCFAs), along with essential amino acids and alkaloids, under glucose-rich conditions. These metabolites support gut health, immunity, and microbiota balance. Our study further demonstrated the pathways through which these metabolites are produced and released by Lactobacillus plantarum, providing deeper insight into its metabolic mechanisms and possible probiotic potential.