Sürdürülebilir Yeşil Kampüs Koleksiyonu / Sustainable Green Campus Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7755

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Department: search.filters.department.Thesis (Master)--İzmir Institute of Technology, Materials Science and EngineeringLanguage: search.filters.language.en

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Now showing 1 - 6 of 6
  • Master Thesis
    Preparation of Albumin Nanoparticles Using an Ionic Liquid Based Microemulsion-Like Method
    (Izmir Institute of Technology, 2018) Demirkurt, Begüm; Adem, Umut; Akdoğan, Yaşar; Akdoğan, Yaşar; Adem, Umut; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Rich drug transportation ability of serum albumin protein has inspired scientists to obtain drug nanocarriers from albumin. In the literature, different methods have been developed to prepare albumin nanoparticles and their drug delivery properties have been studied. Here, this study aims to obtain albumin nanoparticles for a first time using ionic liquid (IL) included systems. Goal of this project is using imidazolium based ionic liquids (green solvent) to prepare albumin nanoparticles as alternative solvents for the commonly used organic solvents. The use of volatile, toxic and flammable organic solvents in the albumin nanoparticle production has various negative effects on both human health and environment. Ionic liquids as non-flammable, non-volatile and non-toxic solvent candidates have attracted considerable attention in recent years both in the literature and in industry. Their ability to solve different types of solutes, designability, special mixing ability with water in IL/water binary systems and environmentally friendly properties cause ILs to overtake traditional organic solvents. This thesis study proposed a novel and environmentally friendly microemulsionlike method for producing albumin nanoparticles in IL/water binary systems. Various experimental parameters such as pH effects, albumin concentrations, water amount, surfactant effects, glutaraldehyde effects, homogenizer effects, etc. were investigated to obtain uniform albumin nanoparticles. As a result, we achieved to synthesize uniformly distributed 200 nm average size albumin nanoparticles at pH 9.0 using 1.5% (w/w) of bovine serum albumin (BSA) in 1-butyl-3-methylimidazolium tetrafluoroborate using TX-100/n-butanol surfactant mixture.
  • Master Thesis
    Structural and Nanohardness Behavior of Low Energy, High Flux Nitrogen Implanted Austenitic Stainless Steel
    (Izmir Institute of Technology, 2018) Dal, Refika; Öztürk, Orhan; Öztürk, Orhan; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    316 austenitic stainless steels (SSs) are one of the most commercial and technological alloys and extensively used in the field of defence, nuclear and biomedical applications due to its excellent corrosion resistance in abrasive and erosive environment. However, this type of steel is rather soft, and these results in poor durability, in particular when this material (316 SS) is in contact with other surfaces. In addition, 316 SS is nonmagnetic at room temperature. In order to make the surface of 316 SS harder, nitrogen ion beam implantation and wear resistant method is applied. Earlier studies of high dose nitrogen ion implantation into the surface of austenitic SSs around 400 °C substrate temperature showed that an expanded austenite phase (The Nitrogen phase in the FCC lattice of 316 SS) gives excellent wear resistance with high hardness value. In this study, type 316 stainless steel (SS) was implanted with low energy (700 eV), high flux (2.9 mA/cm2) nitrogen ions at 400 °C substrate temperature in order to harden its surface. Microhardness and nanohardness measurements were carried out on the nitrogen implanted surface and on the nitrogen implanted cross-section under the applied loads ranging from 6 mN to 30 mN. Both microhardness and nanohardness data suggest that the hardness of the N implanted 316 SS significantly increases compared to the hardness of the substrate material (by a factor of 3 to 4).The hardness increase is believed to be due to the high amount of nitrogen, the thick nitrogen implanted layer and macroscopic residual compressive stresses, the formation of which is verified by θ/2θ XRD scans as lattice expansions about 10 at. %. SIMS profiles suggest concentration-dependent diffusion behavior for the N implanted layers. Based on SIMS and SEM/EDX data, nitrogen implanted layers are 4-5 micron thick and constituting about 28 %.
  • Master Thesis
    Method That Positions Cell-Laden or Cell-Free Matrices at Defined Positions From Each Other Inside a Single Microfluidic Channel
    (Izmir Institute of Technology, 2014) Tarım, Emre; Pesen Okvur, Devrim; Özyüzer, Lütfi; Pesen Okvur, Devrim; Özyüzer, Lütfi; 04.03. Department of Molecular Biology and Genetics; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of Technology
    In recent years, the use of microfluidic has increased in the field of many biological studies. Microfluidic technology has a large area which is a joint product of biology and industry covering all branches of science. The small size of the microfluidic chip offers many advantages in the use of microfluidic. During the analysis, the microfluidic chip offers many advantages such as, use of less material, less waste generation, temporal control, opportunity of analysis under the microscope and high throughput analysis. In addition to these, while microfluidic chip is providing a safe environment for users, via mimicking the physiological environment, it also provides a suitable environment in order to make cell, tissue and organs based assays. Microfluidic devices especially use in cancer studies, chemical analysis, tissue engineering, drug screening, immunology and stem cell differentiation. In this study, we aimed to develop methods depending on the distance to position the MDA-MB 231 breast cancer cells in the microfluidic channels. Firstly, the microfluidic channels were obtained by using the soft lithography and experiments with breast cancer cells were performed using these channels. Breast cancer cells containing matrix was loaded into microfluidic chips and precipitated onto blank matrix by using centrifuge. The aim of repeating this process was to position the breast cancer cells at different distanced locations.
  • Master Thesis
    Investigation of Environmental Durability of Carbon Fiber/Epoxy Composites
    (Izmir Institute of Technology, 2013) Yağmur, Samet; Tanoğlu, Metin; Tanoğlu, Metin; 03.10. Department of Mechanical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Fiber reinforced polymer composites, that have increasing demand in many applications such as aircraft and automotive industry, are usually exposed to different environmental conditions which may be harmful to them. The investigation of their environmental durability is critical for those applications. The objective of this study was to investigate the effects of temperature and moisture on durability of carbon fiber reinforced epoxy composites. For this purpose, 0/90° woven, plain unidirectional and non-crimp biaxial ±45 fabrics were used as reinforcement. The specimens were manufactured using vacuum resin infusion process to obtain relatively high fibre volume fraction ratios. The composites manufactured were exposed to cyclic aging conditions to simulate aircraft flight environment. Hygrothermal, high temperature and freezing conditions were used as in one cycle which was 12 hours long. Moisture absorption was determined by weighing the specimens at regular intervals as a function of aging cycles. Tensile and flexural tests were performed prior to aging and after 500, 1000 and 1500 hours aging. After the completion of aging cycles, the moisture content did not increase significantly due to presence of subzero and high temperatures in aging cycles. The mechanical test results revealed differences based on the fabric types used. It was found that the tensile strength and modulus values of woven composites increased after aging cycles as compared to those of unidirectional and biaxial composites. On the other hand, flexural properties decreased at the end of the aging cycles for the composites aged as test coupons.
  • Master Thesis
    Artificial Neural Networks and Fuzzy Logic Applications in Modeling the Compressive Strength of Portland Cement
    (Izmir Institute of Technology, 2004) Can, Sever; Akkurt, Sedat; Akkurt, Sedat; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Portland cement production is a complex process that involves the effect of several processing parameters on the quality control of 28-day cement compressive strength (CCS). There are some chemical parameters like the C3S, C2S, C3A, C4AF, and SO3 contents in addition to the physical parameters like Blaine (surface area) and particle size distribution. These factors are all effective in producing a single quantity of 28-day CCS. The long duration of 28 day CCS test provided the motivation for research on predictive models. The purpose for these studies was to be able to predict the strength instead of waiting for 28 days for the test to be complete. In this thesis, artificial intelligence (AI) methods like artificial neural networks (ANNs) and fuzzy logic were used in the modeling of the 28-day CCS. The two models were compared for their quality of fit and for the ease of application.Quality control data from a local cement plant were used in the modeling studies. The data were separated randomly into two parts: the first one contained 100 data points to be used in training and the second part had 50 data points to be used in testing stages of the models. In this study, four different AI models were created and tested (3 ANN, 1 fuzzy logic). One of the ANN models (Model A) had 20 input parameters in 20x20x1 architecture with testing average absolute percentage error (AAPE) of 2.24%. The other ANN model (Model B) had four input parameters (SO3, C3S, Blaine and total alkali amount) in 4x4x1 architecture with AAPE of 2.41%. Both of the Model A and the Model B were created in the MatLAB® environment by writinga custom computer code. The last ANN model (Model C) actually refers to 72 differentANN models created in the MatLAB® neural networks toolbox. In order to obtain a model with the lowest error, different learning algorithms, training functions and architectures in combinations were tested. The lowest AAPE among these models appeared to be 2.31%. The fuzzy logic model (Model D) which had four input parameters (SO3, C3S, Blaine and total alkali amount) was created in the MatLAB fuzzy logic toolbox. In order to write the fuzzy rules, the sensitivity analysis of the Model B was utilized. The AAPE of the Model D was 2.69%. The model was compared with the ANN models for its error levels and ease of application. The results indicated that through the application of fuzzy logic algorithm, a more user friendly andmore explicit model than the ANNs could be produced within successfully low error margins.
  • Master Thesis
    Synthesis and Characterization of Hydroxyapatite-Alumina Biocomposites
    (Izmir Institute of Technology, 2006) Şahin, Erdem; Çiftçioğlu, Muhsin; Çiftçioğlu, Muhsin; 03.02. Department of Chemical Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Three component hydroxyapatite-alumina-zirconia composite presents a promising candidate material for bone replacement implants. Two methods were employed to synthesize the composite that is expected to have high bioactivity, high strength and high chemical stability in physiologic environment. Wet mixing and heterogeneous precipitation methods were used for the synthesis. Commercial hydroxyapatite, alum ina and yttria stabilized zirconia were mixed in varying proportions and obtained powders were sintered upto 1300 °C subsequent to dry pressing at 160MPa. An optimum composition of 10-20-70 volume percent zirconia, alumina and hydroxyapatite respectively was found to present the most suitable proportion in terms of sinterability and phase purity. -tricalcium phosphate formation at temperatures higher than 1150 °C was found to be the only source of impurity phase in the material.Heterogeneous precipitation method was applied to synthesize a composite material with a functionally graded structure. The three components were aimed to be coated on one another, zirconia (TZ-3Y) being the core, alumina being the intermediate layer and hydroxyapatite being the outer shell. The bulk composite was expected to have both enhanced mechanical properties and enhanced phase purity due to separation of two reactive phases, hydroxyapatite and zirconia by the alumina layer. The coating was done in two steps using urea as the precipitant, aluminum sulfate as the Al3+ source, calcium nitrate as the Ca2+ source and ammonium phosphate as the P source.Precipitation of aluminum hydroxides on TZ-3Y particulates and precipitation of calcium hydroxides as a nucleation point for hydroxyapatite on cores were facilitated through decomposition of urea above 85 °C in aqueous media. Particle size, distribution and morphology were monitored for alumina coated zirconia samples prepared with varying Al2(SO4)/Zirconia and urea/Al2(SO4) molar ratios. The sample prepared with stoichiometric Al2(SO4)/Zirconia ratio and urea/Al2(SO4) ratio 10 exhibited the most suitable composition and morphology for hydroxyapatite coating. Samples synthesized in the first step were used as cores for hydroxyapatite coating.