Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Protein-enzyme reaction followed by vibrational spectroscopy and dft (density functional theory) characterization(01. Izmir Institute of Technology, 2023) Öztoprak, Nazlı; Güler, Günnur; Öztoprak, Nazlı; Yağmurcukardeş, Mehmet; Güler, Günnur; Yağmurcukardeş, Mehmet; 04.04. Department of Photonics; 01. Izmir Institute of Technology; 04.05. Department of Pyhsics; 04. Faculty of ScienceWhey proteins are crucial for many functions of the human body. Determining the structural properties of the protein with the enzymatic hydrolysis makes it possible to improve food quality, identify allergens and better understand food poisoning. In this study, the structural alterations of β-Lactoglobulin (model whey protein) were investigated during proteolysis. Trypsin was used as a model enzyme. Digestion of β-LG by trypsin at different concentrations were measured by Fourier transform infrared (FTIR) spectroscopy as well as by Raman spectroscopy to identify the degradation of the protein and to verify the enzymatic reactions results at various temperatures in real time. Afterwards, the advanced analysis techniques, two-dimensional correlation spectroscopy (2DCOS) and curve-fitting analysis, were applied. In addition, the experimental measurements were supplemented with DFT simulations. Based on the FTIR spectroscopy results, the most notable changes take place in the amide I (1600-1700 cm-1) and in the amide II (1480-1580 cm-1) regions. FTIR spectroscopic results revealed that the structural elements of β-LG broken down and degraded during the enzymatic digestion. Moreover, the carboxylate groups (COO-) gives rise in the infrared range (1605-1580 cm-1) as released products. Raman spectroscopic results demonstrate that β-LG loses its secondary structure and the product is formed around 1425 cm-1 arising from the carboxylate groups (COO-) due to the digestion. DFT results show that the Raman spectrum of single unit arginine and lysine residues can be predicted by DFT method. Furthermore, DFT calculations give the rise at 1683 cm-1 and 3540 cm-1 caused by C-N vibrations and N-H vibrations arising from the amino groups (NH2+), respectively.Master Thesis Fabrication and Characterization of Perylene Diimide Doped Polyfluorene Based Solution Processed Blue Organic Light Emitting Diodes(2023) Varlıklı, Canan; Demir, Mustafa Muammer; Demir, Mustafa Muammer; Varlıklı, Canan; Demir, Mustafa Muammer; 04.04. Department of Photonics; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyBlue is considered as the major component in many applications of organic light emitting diodes (OLEDs). Most of the polymeric blue emitters including poli[9,9-di-(2-diethylhexyl)-fluorenyl-2,7-diyl] (ADS231BE) attract attention with their solubility and potential in reducing the application costs, but also suffer from wide electroluminescence resulting in color purity issues. Annealing temperature and solvent choice have great influence on morphology and electronic properties. A typical OLED is fabricated by using ADS231BE as the emitter material and effect of annealing temperature on EL properties is investigated between 60C and 150C. OLEDs produced using toluene have shown better efficiency compared to those using chlorobenzene. Regardless of the solvent used, the efficiencies gradually decreased, but the stability and color purity of the devices increased with increasing annealing temperatures. Surface morphologies were examined, and suitable coating conditions were determined. Small molecule orange-red-emitting N,N'-bis(2-ethylhexyl)perylene-3,4,9,10-dicarboxylic diimide (PDI) derivatives were introduced into the blue-emitting conjugated polymer ADS231BE at a concentration of 0.1 wt.%. Electroluminescence, morphology, photoluminescence and Raman analysis of the developed devices were completed to determine the type of aggregation and conformational change caused by PDI doping. Subsequently, to balance charge and improve the electroluminescent character of the devices, a hole transfer layer (HTL) consisting of Poly (N-vinyl carbazole) (PVK) and PVK:1,3-Bis(N-carbazolyl) benzene (mCP) was added to the device structure. Similar morphological and Raman analyses were performed. Compared to the bare ADS231BE containing devices, without changing the CIE coordinate values, approximately, 10 folds of luminance and more than 5 folds of EQE increments were obtained.Master Thesis Desing Strategies for Solar Car Parks: a Case Study for Iztech Library Parking Lot(Izmir Institute of Technology, 2020) Bursa, Enes; Sarı, Emre; Sarı, Emre; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of TechnologyThe world’s need for renewable resources is growing as a result of the global climate crisis. In order to overcome this issue. The Paris Agreement was signed by the nations as a step for solution to this issue. In it, targets for future were set, and the nations pledged to meet these targets. Nowadays investments in energy production from renewable sources are increasing. When compared to 2019, the amount of energy produced from renewable sources grew by 12.5% in 2020. Photovoltaic systems are receiving more investment as a result of their growing efficiency. In 2020, photovoltaic system production climbed by 20.5 percent. Turkey is increasing their investment in photovoltaic systems. It is crucial for universities to be pioneers in energy production from renewable sources. The studies carried out by universities should be taken into account in terms of both increasing knowledge in this area and having people resource who are trained in it. In this study, the open parking area of the library building of the Izmir Institute of Technology were covered with a roof in order to simulate and analyze the installation of photovoltaic solar panels on the roof. These simulations and calculations were done using software called Enact Systems. PVWatts is utilized by Enact system for climate and photovoltaic calculations infrastructure. 560 panels have been installed on the 835 m2 covered parking lot. The installed power of the panels is 224 kW, and they can generate about 302 gWh of electricity annually. This amount is equal to 51% of library consumption. With this production, the amortization period of the investment is calculated as 8 years.Master Thesis Fabrication of Perovskite Solar Cells Using Ultrasonic Spray Coating(Izmir Institute of Technology, 2022) Ceyhan, Eray; Sarı, Emre; Sarı, Emre; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of TechnologyPerovskite solar cells (PSCs) are one of the most prominent research field for the last decade in photovoltaic technology. From 3.8 percent in 2009 to 25.7 percent in 2021 in single-junction architectures, and to 29.8 percent in silicon-based tandem cells, solar cell efficiencies of laboratory-scale devices using these materials have increased, surpassing the maximum efficiency achieved in single-junction silicon solar cells. Therefore, as of now, perovskite solar cells represented the solar technology that was developing the fastest. Perovskite solar cells have gained commercial appeal thanks to their extremely low production costs and promise for even higher efficiency. Their short- and long-term stability are key issues and research topics. In this context, the development of scalable perovskite solar cell fabrication has become essential. A novel ultrasonic spray casting technique is employed by incorporating hot nitrogen gas blowing as a scalable deposition method. We tried to optimize the perovskite film crystallization by applying our technique. With the help of our hot nitrogen gas blowing pipe we are able to enhance the nucleation process and at a desired levels. These investigations are supported by characterization tools such as optical microscope, scanning tunneling microscope, and current-voltage measurement. MAPb(I1-xBrx)3 precursor solution containing DMF and DMSO as solvent was used in our experiments. We examined the effect on the surface roughness change by adjusting the DMF and DMSO ratios. Finally, we construct a device of FTO/ c-TiO2/ m-TiO2/ MAPb(I1-xBrx)3/Spiro-OMeTAD/Au architecture and able to investigate the electrical characteristic of under dark and illumination.Master Thesis Quantitative Phase Analysis in Lensless Digital Inline Holographic Microscopy(01. Izmir Institute of Technology, 2021) Tekin, Hüseyin Cumhur; Varlıklı, Canan; Tekin, Hüseyin Cumhur; Varlıklı, Canan; 03.01. Department of Bioengineering; 04.04. Department of Photonics; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyComputational imaging modalities replace the bulky, complex, and expensive optical components of traditional imaging procedures with numerical reconstruction steps. Digital holographic microscopy is one of the most prominent ones with the possibility of obtaining quantitative phase information by measuring the phase shift change caused by the refractive index of objects. In the lensless digital holographic microscopy system, a pinhole and a light-emitting diode are sufficient to create a holographic pattern on the camera sensor. Here, the optimization of a digital lensless inline holographic microscopy setup was performed to obtain optimal phase value. Also, to retrieve the lost phase information during the recording step, the numerical solution was performed with the single and multi-shot phase retrieval methods. Then, human breast adenocarcinoma (MDA-MB-231) and human myeloid leukemia (U937) cells were analyzed to obtain phase shift, perimeter, and circularity values. These parameters were used to obtain a quantitative differentiation model to replace the traditional labeling or visual confirmation steps with a direct analysis manner. The analysis of respective cells with the classification, object detection, and conditional generative adversarial models can be used directly with pre-trained weights to lessen the computational workloads. With this study, the quantitative analysis with lensless holographic microscopy setup was shown to be a label-free differentiation mechanism to separate cancer cells from monocytes cells which could be used for the early diagnosis of cancer. Also, the proposed method has the potential to be used to identify other cells with links to the diagnosis of different diseases.Master Thesis Identification of Single-Layer Crystalline Structures Through Their Electronic and Optical Properties(01. Izmir Institute of Technology, 2021) Sözen, Yiğit; Şahin, Hasan; Şahin, Hasan; Balcı, Sinan; 01. Izmir Institute of Technology; 04.04. Department of Photonics; 04. Faculty of ScienceA large number of two-dimensional (2D) van der Waals type materials have become a focus of interest in many scientific fields, ever since the thinnest carbon compound, graphene, takes to the stage with its exceptional electronic properties. The outstanding electronic behavior resulting from quantum size effects requires an investigation of the electronic and optical features of materials at the atomic scale. The understanding of such properties of matter within the framework of the theoretical approaches is the first step to shed light on the discovery of electronic and optoelectronic devices including brand new features. This thesis discusses the identification of electronic and optical properties of several types of atomically thin crystals, consisting of 2D and lead-free perovskite structures, by means of density functional theory (DFT). In the first study, primarily, the strong interaction mechanism between Ge atom and single-layer GaAs was studied starting from single atom adsorption to detached germanene layer formation. Following that dynamically stable metallic structures of Janus and alloy type GaGeAs crystals are discovered by performing one-sided and alternated decoration of GaAs single-layer with Ge atoms, respectively. %The Raman spectroscopy is found to be applicable for phase detection as the theoretically calculated Raman spectra of each polytype exhibit distinctive signals. In the second study, bulk and dynamically stable ultra-thin structures of lead-free CsMnCl$_3$ are discussed. According to total energy and electronic band structure calculations, bulk, bilayer, and single-layer structures of CsMnCl$_3$ are robust antiferromagnetic insulators. In third and fourth chapters are devoted to the identification of different stacking types of GaP/GaSe heterobilayers, and two different hexagonal phases of single-layer Germanium Oxide by means of electronic and optical characterization tools, respectively. In these studies, for the purpose of providing an accurate solution for the prediction of absorption, reflectance, and transmission spectra of materials, excitonic effects are considered by employing Bethe-Salpeter formalism following the $G_0W_0$ approximation. Wide range of atomically thin crystal structures studied within the framework of this thesis are verified to be promising candidates for the development of future nano-sized electronic and optoelectronic device applications thanks to their attractive electronic and optical properties arising from strong quantum confinement effects.Master Thesis Design and Fabrication of a Wearable, Flexible Pulse Oximeter(01. Izmir Institute of Technology, 2020) Aydın, Ahmed; Tekin, Hüseyin Cumhur; Tekin, Hüseyin Cumhur; 01. Izmir Institute of Technology; 03.01. Department of Bioengineering; 03. Faculty of EngineeringOxygen is vital for the healthy functioning of tissues and organs. For this reason, it is indispensable to monitor the oxygen saturation of the human body during daily activities in order to improve the quality of life, in the detection and tracking of respiratory diseases. Pulse Oximeter is an electro-optic device that non-invasively measures peripheral oxygen saturation and provides information about how well oxygen diffuses the tissues. Conventional devices are not suitable for daily use due to their bulky structure and designs that restrict movement. With this thesis, the design and production of a flexible reflectance type Pulse Oximeter device that is conformally adapt to measurement suite, can be used all day long and is intended for continuous measurement has been realized.Master Thesis Emission Characteristics of a Solution Processed, Single Layer White Organic Light Emitting Diode(01. Izmir Institute of Technology, 2020) Varlıklı, Canan; Varlıklı, Canan; Gültekin, Burak; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of TechnologyWhite organic light emitting diodes (WOLEDs) are getting more attention day by day because of their some superior properties like viewing angle, refresh rate, flexibility, easy production process and consequently relatively cost-effective natures. Within the scope of this thesis, WOLED has been prepared and characterized by using the single emitter layer prepared by solution process method. In the emission layer, the host material is used for both obtaining the blue region of the visible spectrum and for efficient energy transfer to the green and orange-red guest material. Poly(N-vinylcarbazole) (PVK): 2-(4-Biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) or 1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl] phenylene (OXD-7) matrices are used as host for orange-red emitting material of N,N'-bis(2-ethylhexyl)perylene-3,4,9,10-dicarboxylic diimide (PDI) and green emitting material of perylene-3,4,9,10-tetracarboxy tetrabutylester (PTE). Electron and hole mobility, L-V-J characteristics and morphologies of two different host matrix of PVK:PBD and PVK:OXD-7 were examined. As a result of these evaluations, the appropriate host was determined as PVK:PBD. Host:PTE and Host:PDI emission characteristics were examined and exciplex, electroplex formations were detected. After, Host:PTE:PDI configuration were discussed and high white light properties of optimized WOLED are displayed CIE 1931 coordinates (x, y) of (0.34, 0.36), correlated colour temperature of 4916 K and CRI of 96. Finally, lethal time 70 of the latest devices was examined.Master Thesis Graphene-Like Materials for Electronic Applications(01. Izmir Institute of Technology, 2020) Balcı, Sinan; Şahin, Hasan; Şahin, Hasan; Balcı, Sinan; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of TechnologyTwo-dimensional (2D) materials have gained vast interest in nanotechnology since these materials exhibit extraordinary properties due to electron confinement. Starting with graphene, many other 2D materials with characteristics of metals, semiconductors, insulators, and their magnetic analogues have been studied over the years. Insulators show importance as dielectric layers. Low dimensional metallic materials are used in electrical conduction. Ultra-thin semiconductors have variety of potential applications due to their characteristic band gap. Magnetic analogues of low dimensional materials are used in spintronics, offering high frequency, controllable switching. In addition, defects in these materials alter their physical properties and the concept can be adopted in order to use in different practices. Therefore it is important to study array of such materials and consider the alteration in their lattice theoretically and experimentally. In this thesis, first-principles calculations are used to predict insulating calcium halide single-layers are predicted, determine the effects of strain and V dopant in recently synthesized magnetic semiconducting VI3 single-layers, propose synthesis of magnetic, semiconducting manganese fluorides from manganese dichalcogenides, investigate the affects of defects and simulate scanning tunneling microscopy images in order to compare with experimental results, and finally to determine rather the detection of volatile organic compounds (VOC) such as methanol and ethanol by graphene-based sensors is feasible or not. Experiments are carried out to construct and further investigate the mechanism of VOC detection and working, highly sensitive alcohol sensors.Master Thesis Photophysical Characterization of Green and Blue Emitting Quantum Dots and Their Application in Qd-Leds(01. Izmir Institute of Technology, 2020) Özgüler, Şahika; Varlıklı, Canan; Varlıklı, Canan; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of TechnologyQLED device construction and characterization studies were carried out in which QD nanoparticles synthesized within the scope of TÜBİTAK project no 115F616, and were used as emission layer. By examining the photo-physical and morphological properties of films prepared with the use of quantum dot (QD) nanoparticles, quantum dot light emitting diodes (QLEDs) which are one of the fields of molecular electronics, were applied as an emission layer using the spin coating technique from wet coating processes. The photo-physical and morphological characterizations of the solution and film phase of blue and green emitted QD nanoparticles were made. For the QDs, the concentration difference in the solution phase was characterized and its effects on film properties were investigated. It has been determined that the increase in concentration does not have a dramatic effect on photo-physical properties but seriously affects film thickness and surface roughness. In this case, performance of blue and green light emitting quantum dot diodes (QLED) prepared by the spin-coating technique, where each QD film is used as the emission layer, have been investigated.