Theses (Faculty of Science and Technology)
Állandó link (URI) ehhez a gyűjteményhez
Theses collection of the XX department/institute. The collection was started in 2017.
At the University of Debrecen, in accordance with the 2022 amendment to the 2011 Higher Education Act, student theses are only accessible from devices connected to the University's Eduroam WiFi network or from a university IP address.
“The thesis or diploma work of a student who has successfully passed the final examination shall be stored in full in the academic system of the higher education institution, and a record shall be maintained thereof. The stored theses and diploma works – with the exception of parts classified as confidential in accordance with the relevant legislation – must be made accessible and searchable without restriction through the academic system.” Further info on the National Higher Education Act in Hungarian: Felsőokt. tv. (új) - 2011. évi CCIV. törvény a nemzeti felsőoktatásról - Hatályos Jogszabályok Gyűjteménye.
Böngészés
legfrissebb feltöltések
Megjelenítve 1 - 20 (Összesen 893)
Tétel Korlátozottan hozzáférhető Petrological and Geochemical Characterization of a Granitic Rock from the Velence Mountains, HungaryXu, Tianyue; Benkó, Zsolt; DE--Természettudományi és Technológiai Kar--Földtudományi IntézetThe study investigates the geochemical characteristics of a high-K calc-alkaline, weakly peraluminous sample enriched in LILE, Zr, and REE, without a strong negative Eu anomaly. These features suggest formation in a post-collisional extensional environment during the final stages of the Variscan orogeny. The interpretation is supported by regional geological evidence from the Velence Hills, indicating two-phase intrusive activity in the Late Carboniferous to Early Permian period (271–291 Ma). The sample is closely related to Patka-type granite porphyry and reflects later stages of magma evolution associated with extensional fracturing in a cooling batholith. Overall, it records the transition from syn-collisional to post-collisional tectonics and crustal evolution through progressive melting, differentiation, and crustal thinning.Tétel Korlátozottan hozzáférhető The combined effect of climate change and air pollution in The Association of Southeast Asia Nations (ASEAN)Aphay, Thidtavanh; Lázár, István; DE--Természettudományi és Technológiai Kar--Földtudományi IntézetClimate change and deteriorating air quality are concurrently escalating in Southeast Asia; however, the precise nature of their regional interrelation remains inadequately understood. This study uses a mixed-methods approach, combining a systematic review of existing research, an analysis of quantitative secondary data, and a qualitative examination of policy. Data on PM2.5 concentrations from WHO and IQAir show that all nine ASEAN countries monitored consistently exceed the WHO annual guideline of 5 µg/m³. These results show that climate change and air pollution in Southeast Asia are both worsening problems that need immediate, coordinated policy responses that benefit all four sectors: energy, transportation, land use, and agriculture.Tétel Korlátozottan hozzáférhető Integrating Nuclear Energy with Carbon Capture SystemsMaina, Lynn; Szegedi, Sándor; DE--Természettudományi és Technológiai Kar--Földtudományi IntézetThe thesis investigates whether integrating nuclear energy directly with carbon capture and storage systems is feasible and environmentally and economically superior to fossil fuel-powered alternatives. It assesses two pathways, nuclear-powered point source capture and small modular reactor cluster paired with direct air capture, through techno-economic and lifecycle environmental frameworks; identifies six regulatory gaps; and proposes a blended financial and environmental policy framework to address them. Its central conclusion is that nuclear-CCUS integration is the only current available pathway capable of delivering genuine zero-carbon industrial decarbonisation and land-efficient atmospheric CO₂ removal simultaneously, making it an essential component of any credible net-zero strategyTétel Korlátozottan hozzáférhető Geological Evolution and Mineralization of Archean Greenstone Belts: A Comparative Study of the Barberton Greenstone Belt and the Zimbabwe CratonDhliwayo, Mizpah; Csámer-Skita, Árpád; DE--Természettudományi és Technológiai Kar--Földtudományi IntézetThis study focuses on the geological evolution and mineralization of two major Archean terranes in southern Africa: the Barberton Greenstone Belt and the Zimbabwe Craton. It examines their lithological development, magmatic history, structural evolution, and economically important mineralization, with emphasis on gold and komatiite-associated nickel systems. The study is based on published geological literature, regional syntheses, and existing interpretations rather than new fieldwork or laboratory analysis. As such, the thesis is comparative and interpretive in nature, rather than experimental.Tétel Korlátozottan hozzáférhető Geothermal energy potentials in low- and medium-enthalpy areasGariseb, Giovanni Eben Hage; Tamás, Buday; DE--Természettudományi és Technológiai Kar--Földtudományi IntézetThe thesis discusses the overall potential of exploiting low- and medium-enthalpy geothermal resources. Ranging from their definitions and economic feasibility to direct usage examples and various case studies utilising a comprehensive literature review and analysis.Tétel Korlátozottan hozzáférhető The connction between structural conditions and gold ore mineralisationObiesie, Melody; Csamer-Skita, Arpad; DE--Természettudományi és Technológiai Kar--Földtudományi IntézetThis thesis shows the relationship between the structural conditions and gold ore mineralization. talks about gold ore. states different structures present in the gold ore deposit. It emphasizes three different study areas. It also compares the three sitesTétel Korlátozottan hozzáférhető Stability of RNA of virus yellows from sugar beet (Beta vulgaris) at –20℃ storage temperatureLee, Aram; Thongsuk, Katikarn; Purahong, Witoon; Nagy, Nikoletta Andrea; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetThis study investigates the possibility of storing virus yellows RNA samples at –20°C and determining the most suitable sample type for such storage, between plant sap and total RNA. We quantified the RNA content of three types of virus yellows and the host plant by measuring Cq values using RT-qPCR. The experiments were carried out on two different scales and settings: a smaller experiment with 20 single-infection samples, and a larger experiment with 80 random mixed-infection samples to represent lab-controlled and practical field data, respectively. We compared the statistical significance of differences in measurement data before and after 6 months of storage at –20°C. Our results revealed that RNA of virus yellows from sugar beet remains detectable in comparable quantities after –20°C storage as in the initial total RNA, regardless of the sample type used. This observation aligns with our hypothesis that RNA from both sample types of virus yellows displays higher stability than previously established and can be preserved at –20°C for long-term storage. These findings underscore the possibility of using –20°C freezing system as an alternative to –80°C, which is commonly adopted as the standard in molecular laboratories to prevent RNA degradation. Our data can enable more informed research planning involving virus yellows RNA by providing greater flexibility in storage costs and space.Tétel Korlátozottan hozzáférhető HEPARIN BINDING OF THROMBOSPONDIN-1 IS REGULATED BY A NEWLY IDENTIFIED PKA PHOSPHORYLATION SITEPramudya, Rengganis Ayu; Boratkó, Anita; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetIntroduction: Thrombospondin-1 (TSP1) is a multifunctional glycoprotein involved in cell-to-cell and cell-to-matrix communication. Its N-terminal domain contains a well-defined, high-affinity heparin-binding region that mediates interactions with heparan sulphate proteoglycans and other extracellular ligands. These interactions influence a wide range of cellular processes, including cell adhesion, spreading, proliferation, and migration. Previous structural and biochemical studies have identified a cluster of positively charged residues (most notably R29, R42, R76/R77) that form the core of the TSP1 heparin-binding surface. Our workgroup has identified Ser44 as a protein kinase A (PKA) phosphorylation site in TSP1, located within the heparin-binding region, suggesting that phosphorylation at this position may modulate heparin affinity through local structural or electrostatic effects. Aim: The aim of this study was to investigate whether phosphorylation at Ser44 influences the ability of the TSP1 N-terminal domain to bind heparin. Material and methods: Site-directed mutagenesis was used to introduce substitutions at Ser44, generating Ser44Ala (phosphonull) and Ser44Asp (phosphomimetic) variants of TSP1. Recombinant TSP1 N-terminal fragments were then expressed in BL21(DE3) E. coli cells. For the heparin-binding assay, equal amounts of each recombinant protein were incubated with heparin-agarose beads. The input, unbound, and bound samples were analyzed by SDS-PAGE, followed by gel staining or Western blotting. Results: Sequencing confirmed the successful introduction of the Ser44Ala and Ser44Asp mutations. All recombinant TSP1 N-terminal proteins were successfully expressed at comparable levels. In the heparin-agarose assay, both the wild-type and the phosphonull mutant bound efficiently to heparin. In contrast, the phosphomimetic mutant exhibited markedly reduced binding. Conclusion: Our findings support the concept that phosphorylation of Ser44 plays a regulatory role in modulating heparin binding by the TSP1 N-terminal domain.Tétel Korlátozottan hozzáférhető Interaction between transition metal ions and tau protein fragmentsShahzadi, Iqra; Várnagy , Katalin; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThis study looks at how Ni(II) ions interact with a small peptide (Ac-TSKCGS-NH₂) that mimics parts of the tau protein involved in Alzheimer’s disease. It shows that specific amino acids, especially cysteine, help bind metal ions effectively at near-physiological pH. The peptide forms stable complexes with Ni(II), where the metal is held by nitrogen and sulfur atoms in a square planar structure. Experimental techniques confirmed that these complexes remain structurally stable over time. However, unlike copper, Ni(II) and its peptide complexes produce very little reactive oxygen species (ROS). In contrast, Cu(II)-peptide systems, particularly those containing cysteine, show much higher ROS activity. Overall, the type of amino acid involved plays a key role in determining both metal binding and oxidative behavior.Tétel Korlátozottan hozzáférhető Chromogenic Plate Assay and Cell Wall Detachment Protocol for Extracellular β-Xylosidase from Pichia pastorisDe Silva, Keraminiyage Dasuni Vimansana; Teres, Barna; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThis study improved the selection and recovery of recombinant Komagataella phaffii transformants producing β-xylosidase using an X-Xyl activity-based plate assay, leading to identification of a high-producing clone. Methanol induction under the AOX1 promoter enabled increasing enzyme activity over 120 hours, confirming successful secretion. However, total extracellular protein exceeded enzymatic activity, indicating the presence of inactive or non-target proteins. A significant fraction of β-xylosidase remained associated with the yeast cell surface, reducing apparent extracellular yield. Detachment experiments showed that mannose, glucose, and DTT most effectively released the enzyme, suggesting carbohydrate- and redox-related interactions.Tétel Korlátozottan hozzáférhető NEW O-PYCLEN MACROCYCLIC LIGANDS WITH HYDROXAMATES PENDANT ARMS: PREPARATION AND CHARACTERIZATION OF Mn(II) AND Sc(III) COMPLEXESTety Izzati, Binti Tiar Izam; Csupász, Tibor; DE--Természettudományi és Technológiai Kar--Kémiai IntézetThis MSc thesis describes the synthesis and coordination chemical characterization of two novel O-pyclen-based macrocyclic ligands with monodentate (OPC1HA) and bidentate (OPC2HA) hydroxamate pendant arms, developed as potential alternatives to toxic gadolinium-based MRI contrast agents. A new synthetic route using microwave-assisted alkylation and mild TFA/Et₃SiH deprotection significantly improved reaction yields and reduced deprotection time from days to one hour. The Mn(II) complex with OPC2HA exhibited exceptionally high relaxivity, outperforming acetate analogues and demonstrating strong potential as an MRI contrast agent, though its kinetic inertness was only moderate. The Sc(III) complex with OPC1HA showed thermodynamic stability but very low kinetic inertness, making it unsuitable for in vivo PET imaging applications. Overall, while OPC2HA shows promise as a high-relaxivity Mn-based contrast agent, the vulnerability of hydroxamate arms to protonation necessitates further ligand optimisation to improve kinetic inertness for biomedical use.Tétel Korlátozottan hozzáférhető Developmental and Testing of a Field Random Samplind Designation MethodsSarwar, Amna; Ban, Miklos; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetThis study tests a new field sampling method that uses dice rolls and RTK GPS to randomly select sampling points in ecological surveys. The method was tested in the Botanical Garden of the University of Debrecen across five locations, producing 125 sampling points. Results show the method achieves statistically valid spatial randomness, comparable to computer-generated random sampling, without needing any software or digital preparation before fieldwork.Tétel Korlátozottan hozzáférhető The Effect of Parental Supplementation with Essential Oils on Japanese Quail Offspring BehaviorAlhaiyach, ibrahim jamal; Nemeth, Zoltan; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetThis thesis examines the effects of parental dietary supplementation with essential oils and post-hatch dietary corticosterone exposure on the growth and behavior of Japanese quail offspring. The study evaluates whether parental nutrition can influence offspring development and mitigate stress-related effects. Results showed that corticosterone exposure reduced body weight in several groups, indicating a negative impact on growth. However, parental supplementation with basil and peppermint essential oils did not produce consistent transgenerational effects. Behavioral tests revealed minimal differences across treatments, although corticosterone-treated chicks showed signs of increased anxiety and activity in specific cases. Overall, the findings suggest that stress hormones play a stronger role than parental diet in shaping offspring growth and behavior under the conditions tested.Tétel Szabadon hozzáférhető Collective Escape Behaviour in Springtails: Effects of Population Density on Movement Synchrony and Escape Response DynamicsNurlan, Zhannur; Oláh , Gergő; Barta, Zoltán; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetThis thesis studies how population density shapes collective escape behaviour in springtails, using high-quality slow-motion video recordings and manual individual tracking. Individual trajectories of springtails were annotated frame-by-frame and fed into a multi-metric computational pipeline covering pairwise speed synchrony, spatial autocorrelation, group polarisation, centre-of-mass displacement, and radial and tangential velocity decomposition.Tétel Korlátozottan hozzáférhető Antifungal Activity of Lactobacillus casei and Lactbacillus pentosusShandham, Rojita; Barna , Terez; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai IntézetThis study investigated the ability of different carbohydrates to support the growth of Lactobacillus casei and Lactobacillus pentosus, two probiotic strains. I isolated the extracellular proteins produced by those strains when grown on tested carbohydrates. Their antifungal activities were tested against four fungal species, including opportunistic pathogens such as Candida krusei and Kodamea ohmeri as well as Candida stigmae and Candida riodocensis as plant-associated yeasts. The results showed that both bacterial strains produced proteinaceous compounds with significant antifungal activity, although effectiveness varied depending on the fungal species and the carbohydrate substrate used. These findings suggest to develop symbiotic pairs of Lactobacillus casei and Lactobacillus pentosus with appropriate carbohydrates that function as prebiotics.Tétel Korlátozottan hozzáférhető The effect of deoxycholic acid, a bacterial metabolite, on intestinal motility.Jafo, Rima; Uray, Karen Lee; DE--Természettudományi és Technológiai Kar--Biológiai és Ökológiai Intézet1. This study examined the effects of deoxycholic acid (DCA) on mouse ileal contractility. 2. An organ bath system recorded motor responses to DCA at 100, 500, and 1000 nM. 3. DCA was tested under both basal conditions and carbachol-induced hyperactivity. 4. Results show DCA selectively inhibits carbachol activity while preserving the spontaneous contractility. 5. DCA acts as a "physiological buffer" to stabilize intestinal movement during over-stimulation. 6. These findings support targeting bile acid pathways to treat motility disorders like IBS and IBD.Tétel Korlátozottan hozzáférhető APPLICATION OF MACHINE LEARNING FOR REAL-TIME FAULT DETECTION IN ELECTRICAL MACHINESHussein, Kareem Khaled Ahmed; Trencsényi, Reka; DE--Természettudományi és Technológiai Kar--Fizikai IntézetThis thesis presents a complete, low-cost vibration-based condition monitoring system designed for the early detection of faults in induction motors using modern machine learning techniques. Driven by the growing need for predictive maintenance in industrial settings, the work integrates all steps of the measurement and classification process, starting with vibration acquisition. This is followed by analog signal conditioning, digital sampling, wireless data transmission, and finally, machine learning-based fault classification. A low-noise ADXL335 accelerometer senses mechanical vibrations, while a custom-designed analog front end handles AC coupling, bias shifting, amplification, filtering, and protection to ensure signal compatibility with the ESP32 12-bit SAR ADC. The embedded system conducts timer-driven sampling at 6 to 10 kS/s, streams the digitized signal via UDP over Wi-Fi, and enables real-time data acquisition without significant packet loss. A digital twin of the motor, created in MATLAB/Simulink, generates high-quality synthetic datasets that represent various fault conditions, including rotor imbalance and shaft misalignment. These synthetic signals are combined with real measurements to train multiple machine learning models, such as Support Vector Machines, Random Forests, and a lightweight Convolutional Neural Network. The results show that the proposed approach can reliably identify subtle changes in vibration signatures and accurately predict early-stage motor faults. The combination of embedded data acquisition, analog conditioning, and data-driven classification offers a flexible and scalable base for predictive maintenance. Overall, this work highlights that modern machine learning methods, when used with inexpensive hardware platforms, can significantly improve the reliability and efficiency of industrial motor systems, providing a practical way toward intelligent maintenance solutions.Tétel Korlátozottan hozzáférhető DESIGN AND IMPLEMENTATION OF A PLC-CONTROLLED HVAC SYSTEM FOR ENERGY-EFFICIENT CLIMATE MANAGMENTIbrahim, Mohamed Ibrahim Soliman; Misák, Sándor; DE--Természettudományi és Technológiai Kar--Fizikai IntézetThis thesis presents design and implementation of a PLC-HVAC controlled system for a small commercial office. The project was built using Eaton easy-E4-DC-12TC1 PLC as a main controller. Using IEC 6131-3 programming Languages such as LD - ST, I could able to implement 5 different operation modes based on air quality, occupation percent, and user preferences ( Auto - Manual - Eco - Boost - Night) through three Structured Text User Function Blocks that compute mode-based fan speed, air quality demand from CO₂ and humidity sensors, and select the maximum of both to drive an Eaton DC1 Variable Frequency Drive with a 0–10 V analogue output. A supervisory layer was developed across an HMI touchscreen, a SCADA system, and a web-based visualization dashboard, with all 16 functional test cases passing successfully in the physics laboratory environment.Tétel Korlátozottan hozzáférhető Components in Power Grids and Analyzing Disconnectors and Circuit Breakers with Practical CalculationsPervaiz, Omaima; Dr Janos, Kosa; DE--Természettudományi és Technológiai Kar--Fizikai IntézetI have worked on researching power grids and multiple components of power grids to write this thesis. I have better my understanding of how power grids operate, how switchgears are chosen and what multiple types of transformers existed. I have shown calculations to decide how to choose a suitable switchgear.Tétel Korlátozottan hozzáférhető Analysis of Optical measurements by Machine Learning and Analytical Models for SensorsMohammad Shoeb, Mohammad Shoeb; Petrik, Peter; DE--Természettudományi és Technológiai Kar--Fizikai IntézetThis thesis evaluates whether machine learning models can surpass a physics-based analytical solver for film thickness retrieval from spectroscopic ellipsometry data under varying noise, resolution, and dataset size conditions. A large synthetic dataset generated via a Fresnel three-layer model is used to benchmark Linear Regression, Random Forest, and Multilayer Perceptron models against a grid-search analytical baseline. While the analytical solver achieves perfect accuracy on clean data due to model consistency, it degrades significantly under non-Gaussian noise, whereas machine learning models remain stable and achieve lower RMSE in noisy conditions. The study shows that dataset size is the primary constraint on accuracy, while spectral resolution can be reduced with minimal performance loss, and that predictive information is concentrated in a limited subset of wavelengths. Overall, the results define the regimes where machine learning outperforms analytical inversion and provide guidelines for efficient ellipsometer design and calibration.