Master Tezleri

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Coating of spinel layers on alumina by electrostatic spray deposition (ESD)
(01. Izmir Institute of Technology, 2023-04) Demirkol, İrem; Akkurt, Sedat
MgAl2O4 spinel layer was coated on dense alumina pellets by advantageous ESD among the other deposition methods in terms of providing a simple, inexpensive setup and good control of the layer morphology. The main goals are successfull deposition of spinel layers on alumina pellets by ESD, to investigate the effect of ESD parameters (working distance, flow rate of precursors, applied voltage) on coating microstructure by conducting full factorial design experiments and to determine the best experimental conditions for a porous layer. Besides, MgCr2O4 layer was coated on dense alumina and MgAl2O4 layer was deposited on bisque-fired alumina pellet to extend the scope of the work. Alumina powders were compressed and sintered, respectively to obtain pellets. MgAl2O4 spinel precursor solution was sprayed on the alumina pellets by changing the parameters accordingly the full factorial design. MgAl2O4 and MgCr2O4 solutions were also sprayed on the bisque-fired and the dense alumina pellets with the parameters given the best porous layer. Elemental analysis of the residues obtained after evaporation of the solutions by energy dispersive X-ray spectroscopy (EDX), both unheated and post-heated residual powders of solutions by X-ray diffraction (XRD) and surface morphologies of coated pellets by scanning electron microscopy (SEM-EDS) were analyzed. Spinel layers on alumina pellets were successfully coated by ESD, which could provide variable surface morphologies. The optimum conditions for a porous layer were obtained as working distance of 15 mm, flow rate of 0.25 mL/h and applied voltage of 6 kV in this study. The coatings on the pellets before further heating were amorphous. Post-heating of the pellets were required to obtain crystalline spinel structure.
Assessment of land use change impacts on hydrological parameters in Porsuk River Basin - Turkey
(01. Izmir Institute of Technology, 2023-07) Zulal, Khalilullah; Gündüz, Orhan; Alp, Emre
Land Use Land Cover (LULC) change is considered to play an essential role in river basin hydrology. Climate change, and increase in urbanization have disrupted the hydrological parameters pattern in Porsuk River Basin (PRB). The current study is aimed to investigate the LULC change impacts on surface runoff, groundwater, evapotranspiration, and lateral flow parameters in the five sub-basins of the PRB under different LULC development scenarios (1990 & 2006) and one climate period (1989- 2010) through hydrological modeling. In this study, the Soil and Water Assessment Tool (SWAT) model was utilized to analyze the hydrology of the river basin at watershed scale. The hydrological pattern characterization is based on five discharge gauges monitored by State Hydraulic Works (DSI) in the basin. The Kiranharmani, Parsibey, and Porsuk Ciftligi subbasins, the yearly increase in surface runoff reached 25%, 18%, and 12.91%, respectively, are more affected by landuse changes. The Scenario 2, contrary to Scenario 1, showed a noticeable reduction of groundwater infiltration in all subbasins with exception of Parsibey, due to rapid increased area of residential regions. In comparison to the 1990 LULC, changes in the 2006 LULC have a greater overall impact on hydrological processes in all sub-basins of the PRB. Therefore, it is believed that changes in specific LULC classifications can be linked to the reaction to changes in hydrological processes in a subbasin. Overall, this research is believed to be among the first to be done in the PRB, and the findings are thought to be helpful for water management.
Kinetics of silica polymerization at various conditions
(01. Izmir Institute of Technology, 2022-03) Hasköylü Toker, Öykü Çağ; Demir, Mustafa; Demir, Mustafa Muammer; Baba, Alper
Silica is the most abundant element on Earth because the Earth's crust is composed mainly of metal silicates. The source of this silica is mainly volcanic rocks, which come to the surface through tectonic activity and are the primary source of heat for geothermal activity. The silica concentration in a geothermal fluid is higher than the solubility limit of natural waters, so scaling of (metal) silicates is often observed in geothermal operations. This situation has become critical for geothermal power plants. Since silicates have an insulating structure, they lead to a reduction in energy efficiency during fluid transport. The formation of silica-rich deposits should be understood to minimize the negative effects of the scaling. Briefly, silicic acid molecules in the reservoir system are condensed, and the monomeric silicic acid molecules bind to each other via covalent bonds. In the course of this reaction, dimers, tetramers and short oligomers are formed, and eventually a large polymeric silica network is formed. In the presence of metals, both the kinetics of polymerization and the structure of the network are inevitably affected. In this study, the presence of kinetic parameters (different salts such as FeCl3, MgCl2, AlCl3 and NaCl), the reaction process, the rate and the activation energy of silica polymerization at different temperatures between 25 and 90 °C were investigated. The yellow silicomolybdate method was used to determine the concentration of monomeric silica. The order of the polymerization reaction was given as 3. The polymerization occurs in the initial phase, in the first 40 minutes, where the activation energy was about 29.52 ± 2.28 kJ/mol and the rate constant was of the order of 4x10-8 mol-2∙L2∙s-1. The results also confirmed that pH has a stronger effect on the kinetics of silica polymerization than temperature. The neutral solution decreases rapidly, while the acidic solution has an induction phase in the first hour of polymerization. Different temperatures did not affect the polymerization rate as much as pH. At 25°C the experiment showed the fastest polymerization, but at 90°C the low concentration changed from the beginning. During all these experiments, no scaling of amorphous silica was observed, only the polymerization of silica.
Effects of zirconia and hydroxyapatite nanoparticles on the mechanical properties of the resin-based dental composites
(01. Izmir Institute of Technology, 2023-06) Tunca Taşkıran, Senagül; Tanoğlu, Metin; Tanoğlu, Metin
The majority of the population suffers from dental caries, one of the most common chronic diseases. Therefore, restoration of teeth is an urgent need. The materials used in restoration are composites prepared by adding inorganic components to the polymeric matrix. However, failure due to fractures and secondary caries is still the main problem. Therefore, studies are continuing to improve the mechanical properties and water sorption and solubility properties of the composite. In this study, effects of zirconia, which improves the mechanical properties, and hydroxyapatite nanoparticles, which are the components of the tooth, on the mechanical properties of the composite were investigated. According to the literature, amounts of additives were determined as 1 and 2 wt.% for zirconia and 3 and 5 wt.% for hydroxyapatite. Nine different composites were prepared by mixing with hand spatulation method and mortar mill. The flexural strength and modulus, compressive strength, depth of cure, water sorption and solubility properties of the composites were investigated. Samples were characterized by using Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Zirconia and HA particles significantly improved the flexural and compressive strength of the composites. The highest flexural strength was obtained in the sample containing 5 wt.% hydroxyapatite and 1 wt.% zirconia, with an increase of 58% compared to the control sample. The highest compressive strength was obtained in the sample containing 3 wt.% hydroxyapatite and 2 wt.% zirconia, with an increase of 22% compared to the control sample. Therefore, zirconia and HA nanoparticles have a synergistic effect.
An investigation of performance indicators for stage acoustics in music halls
(01. Izmir Institute of Technology, 2023-03) Kuşcu, Duygu; İlal, Mustafa Emre
It is vital for concert halls to provide suitable acoustic conditions, as they provide the physical environment in which the communication between musicians and the audience is established. Although the acoustic conditions in these halls have been studied in detail for audiences, relatively little is known about the conditions under which musicians perform on stage and how they perceive acoustics. This thesis research investigates how the acoustics of the hall in which they perform are perceived by the musicians and how the objective data obtained through measurements carried out on stage matches the evaluations of the musicians through quantitative methods. Acoustic measurements were carried out in the Main Hall of the Ahmed Adnan Saygun Arts Center Izmir. Evaluations by the orchestra musicians about their own home stage were collected through questionnaires using a 10-point semantic differential scale for subjective acoustic parameters. A total of 33 musicians who regularly perform on this stage participated in the study as respondents. Compatibility between subjective data obtained from opinions and objective data obtained from measurements were compared. The main objective of this investigation was to scrutinize the tools and parameters that are recommended for acoustic design of concert hall stages, and provide further data for studies into understanding musicians' preferences and objective parameters that are being developed to reflect them. The correlations among subjective parameters on stage acoustics, were examined. Overall Acoustic Impression was found to be highly correlated with Hearing Others (0.833) and Support (0.753). This was supported by the objective measurements where STearly values were in a highly favorable range with a mean of -13.7 dB for this stage that is generally deemed to have good acoustics by musicians. The objective and subjective support parameters were found to be useful indicators within the limited context of Ahmet Adnan Saygun Arts Center Main Hall.
The structural conservation problems of traditional houses in Eryeri, Mardin, Artuklu
(01. Izmir Institute of Technology, 2023-06) Ercan Gündüz, Yasemin; Turan, Mine; Aktaş, Engin
The aim of this study is to document the construction techniques, material usage, and structural failures of the traditional houses in a village of Mardin, Eryeri, in order to guide a conservation aimed development plan that will be prepared in the future and enhance the related rehabilitation implementations. Eight houses that have preserved their authenticity were selected. Field survey focusing on the structural elements such as foundations, walls, floors, and roofs was conducted with the conventional techniques of architectural restoration. Both failures and also alterations of the buildings were documented. The changes and alterations of the houses are documented. Visual analysis of the constructional qualities was made with Archicad23 tools. Comparison with the traditional houses in the vicinity was made with reference to data gathered via field survey, literature review and archive research. As a result, the traditional houses are integrated with the rocky terrain of the region and in masonry system. There is an intense use of local stone, Yellow Limestone. Vaults are common superstructure elements, but timber floor is also possible. The walls are stone masonry in all. The common structural problems are demolition of structural elements such as roofs. The causes of severe failures are neglect and natural aging. The reinforced concrete additions flanking to the authentic structures also cause failure. Within the scope of the conservation plan, it is important to prevent reinforced concrete annexes and to intervene the annexes that cause excessive loads urgently.
Investigation of probiotic properties of cold brewed and fermented cold coffee beverage
(01. Izmir Institute of Technology, 2023-05) Semiz, Şevval; Baysal, Ayşe Handan
The goal of the project was to produce a functional probiotic fermented cold brewed coffee that is perapered with medium roasted, grinded Colombian Arabica beans with patented probiotic yeast Saccharomyces boulardii that can survive in human gastrointestinal conditions. With pasteurization of the product, safe fermentation environment and long shelf life was achieved. Coffee brew samples were prepared with different techniques to understand the effects of fermentation and glucose fortification to fermentation media on coffee chemistry, microbiota and sensory characteristic. One of the three coffee brews was only pasteurized (P), one of them fermented (F) and the other was fermented with glucose (FG). The cold brewing and fermentation were performed respectively at 22 °C and 30 °C for 24 hours. The brewed samples were pasteurized before fermentation at 65 °C for 30 minutes. Each sample was examined during their 120 days shelf life (at +4 °C). Although the probiotic yeast enabled fermentation in coffee, it did not survive after the first week. Pasteurization was successful, so pathogen growth was not detected in any of the samples during their shelf life. While FG was evaluated as undrinkable, the other samples gave positive results in terms of sensory. Caffeine, chlorogenic acid, and ethanol levels were significantly altered during shelf life. This is the first study in which chemical, microbiological and sensory analyzes of cold coffee that was brewed via cold immersion method, pasteurized and fermented with patented S. boulardii yeast during shelf-life were conducted, and will lead to new studies in this field.
Experimental investigation and optimization of laser surface treatment parameters for 1.2379 (AISI D2) tool steel
(01. Izmir Institute of Technology, 2023-06) Özbey, Sayit; Artem, Hatice Seçil; Kayahan, Ersin
Laser surface treatment has been used as a cost-effective method to improve the surface qualities of materials, such as hardness, strength, roughness, corrosion resistance, chemical resistance and coefficient of friction by modifying their structure and physical features using laser beam heat. In this thesis, surface properties such as hardness and roughness of 1.2379 cold work tool steel, a commonly used material in the die and mold industries for injection mold inserts, were investigated both experimental and numerical (regression analysis, optimization) studies. In the experimental part of the thesis, 1.2379 cold work tool steel surface was treated using a commercially available industrial Ytterbium low-power pulsed fiber laser. Laser parameters including average power, repetition rate, line spacing and scan speed were considered as input parameters while hardness and roughness were used as output parameters. Input parameters used in the experiments were produced by using a 34 full factorial design. The effect of laser parameters on the surface properties of 1.2379 cold work tool steel was investigated by hardness and roughness measurements. Using the results of the measurements different regression models were conducted and the best fit was chosen. As a result of regression analysis, it is obtained that the second-order multiple non-linear model is the best regression equation for hardness and the second-order logarithmic multiple non-linear model is the best for roughness Following the experimental study and regression analysis, an optimization study was performed using Wolfram MATHEMATICA 11.3 to determine the optimum laser parameters for the hardness and roughness of 1.2379 cold work tool steel. In the optimization, Random Search (MRS), Simulated Annealing (MSA), Differential Evolution (MDE) and Nelder-Mead (MNM) methods were used for different optimization scenarios. By determining the optimum parameters, this thesis contributes to enhancing the surface properties, hardness and roughness, of 1.2379 cold work tool steel.
Optimization of energy consumption and thermal comfort in historic buildings: Case study of İzmir National Library building, Türkiye
(01. Izmir Institute of Technology, 2023-03) Özsavaşcı, Umut; Durmuş Arsan, Zeynep; Gökçen Akkurt, Gülden
The 'library,' as a building type, is the visiting space of researchers and storage space of wisdom of past and present thinkers. Historic libraries host unique pieces of cultural heritage such as books, manuscripts, documents, maps, artifacts, paintings, sculptures, and frescos from the previous generations. The thesis aims to reduce energy consumption and improve occupants' comfort while paying attention to degradation risks of paper-based collections in the historic İzmir National Library Building, Türkiye. Thus, it examines building retrofit actions with different impact criteria and conducts the optimization tool to define the most optimal ones. First, three degradation risk assessment procedures were determined for the paper-based collections of the İzmir National Library Building. Within the scope of the thesis, the library building was monitored between 01.10.2016 - 01.10.2017. According to the results of the monitoring process, mechanical, chemical and biological degradation risk analyzes were carried out. The digital simulation model of İzmir National Library was prepared in DesignBuilder v. 7.0.0.102 software and calibrated monthly for a year via hourly air temperature data. Three retrofit optimization scenarios, i.e. neutral, low and high risk impact criteria, were defined by grouping different design variables such as glazing type, exterior door material, pitched roof floor construction, exterior wall construction, heating set point and cooling set point of HVAC system. The objective of optimization was reducing energy consumption and discomfort hours at the same time. The simulation results showed that all three retrofit actions reduced energy consumption and discomfort hours. Scenario 3 was the most successful among other scenarios, providing energy savings by 26.6% and reducing discomfort hours by 80.3%, according to the base case. Besides, there was no significant change in the degradation risk analyzes according to the base case.
The effects of various Intelligent Transportation Systems applications on the transportation disadvantaged groups
(01. Izmir Institute of Technology, 2023-05) Özsoy, Damla; Duvarcı, Yavuz
Many applications developed within the framework of Smart Transportation are developed to facilitate urban journeys and reduce costs. However, Intelligent Transportation Systems applications have not always been the applications that can be easily used by disadvantaged groups. With this study, it is aimed to develop technological suggestions to the discriminatory effects of ITS applications on the disadvantaged in general, transportation disadvantaged, and non-disadvantaged individuals, address to their special needs and the problems faced by individuals. Descriptive statistics, category analysis and One-way Anova Test were used as methods. According to the results, more than half of the disadvantaged individuals are unfamiliar with the concept of Intelligent Transportation Systems. The applications they use while traveling or in public transportation are the applications that they physically see, know, and use in their daily lifestyles in the city, or their use has become mandatory. Transportation disadvantaged groups generally know about ITS applications and use them actively during the day. It is understood from the problems observed in the city of Izmir that the development of spatial applications rather than mobile and web applications for the disadvantaged groups, the elimination of the malfunctions of Smart stops and Smart pedestrian buttons and the installation of new ones at smart stops, addressing the traffic congestion by making alternative transportation solutions, etc. In addition, smart stops, passenger information boards, smart passenger button, Green man, new map applications, Barrier-Free Smart Transportation, WeWalk, Horus, New public transportation vehicles should be implemented for the city of İzmir.
Effect of column-beam moment capacity ratios on the frame plastic failure mechanism
(01. Izmir Institute of Technology, 2023-03) Akhtari, Rohullah; Dönmez, Cemalettin
The strong-column weak-beam design ratio plays a crucial rule to design the structures particularly for high seismic region. Interestingly, the ratio to be used is still under spotlight for research. Observations and analytical studies have demonstrated that the ratio's effectiveness varies with some parameters. One of these parameters is the number of stories in a building. The failure mechanism of the structures depends on this ratio and the design ratio efficiency seems to change as building's stories increases. This efficiency also seem to saturate at a point depending on number of stories. In this study, three case studies have been assessed and analyzed. Each case study contains three reinforced concrete frames with different strong-column weak-beam design ratios that varies from 1.2 to 3.0. For each case study, the design ratios are ranged into three parts: (i) ratios between 1.2 to 1.5; (ii) ratios between 1.5 to 2.0; (iii) ratios between 2.0 to 3.0. The Turkish Earthquake Regulation (2018) has been utilized for the design procedures. The pushover and time-history analysis of frames were performed using OpenSees software framework (McKenna et al., 2010). Columns have been modeled with fiber sections and the beams have been modeled with concentrated rotational springs at the ends. Both members are accepted to be linear in between. The plastic hinge occurrence at the end of members were monitored to observe the frames' failure mechanism.
Application of artificial neural networks to structural reliability problems
(01. Izmir Institute of Technology, 2023-06) Köroğlu, Fahri Baran; Aktaş, Engin; Maguire, Marc
The contemporary approach in structural engineering indirectly addresses uncertainties arising from load and resistance parameters by using safety factors. To consider these uncertainties in structural engineering, it is necessary to incorporate their statistical properties into the analysis and design process. However, this approach requires the calculation of challenging multi-fold probability integrals. Approximate methods known as FORM and SORM have been developed as an alternative to calculating those integrals. Unfortunately, these methods might have accuracy and convergence problems depending on the problem at hand. Simulation-based structural reliability methods have been developed to overcome the problems associated with approximate methods. The main problem with these methods is that they are often computationally expensive when along with finite element analysis, or it is hard to implement them when a more specific method is chosen to reduce computational costs. In this study, artificial neural networks have been applied to structural reliability problems to obtain accurate probability estimates with low computational cost. A special type of learning algorithm called Bayesian Regularization was used in the training of artificial neural networks. Additionally, details of the application of artificial neural networks to structural reliability problems are provided. At the end of the study, the advantages and disadvantages of applying artificial neural networks to structural reliability problems are presented and compared with other known structural reliability methods. Additionally, a new convergence criterion and an adaptive algorithm have been developed. It was observed that applying artificial neural networks to structural reliability problems provides both efficient and accurate probability estimates.
Examination of therapeutic potential of luteolin on acute lymphoblastic leukemia cells and changes in macromolecules
(01. Izmir Institute of Technology, 2023-07) Çetinkaya, Melisa; Baran, Yusuf
Acute lymphoblastic leukemia (ALL) is a genetic disease that arises from the various recurrent genetic alterations blocking the differentiation of the precursor B-and T-cells, resulting in the aberrant proliferation and survival of immature lymphoblasts within the peripheral blood and bone marrow. T-ALL is an aggressive type of ALL, and the current treatment strategies, including the high-intensity combination chemotherapy, result in different side effects which are difficult to accept or ultimately lead to the death of patients as substantial toxicity of those chemotherapeutics is known to healthy cells alongside with the cancer cells. Therefore, there is a need to identify nontoxic, costeffective, potent, and readily available treatment options for T-ALL patients. One alternative option is the flavonoids in cancer therapeutics, which are secondary metabolites of plants mainly responsible for plants' colors and flower aromas. Luteolin is an extensively researched member of the flavonoids with anticancer properties shown in various cancer types, except for the T-ALL. This study demonstrated Luteolin's time- and dose-dependent antiproliferative, cytostatic, and apoptotic effects on T-ALL cells for the first time in the literature. Also, the macromolecular changes caused in response to Luteolin treatment in T-ALL cells were examined for the first time. As a consequence, it was found that Luteolin had antiproliferative, apoptotic, and cytostatic effects on T-ALL cells, suggesting its therapeutic potential and was demonstrated to cause an increase in the lipid-to-protein ratio and the hydrocarbon chain length of the lipid acyl chains in a dose-dependent manner on T-ALL cells.
Using smart card data for mode shift estimation: Enhancing the efficiency of İzmir's transit system
(01. Izmir Institute of Technology, 2023-06) Kesmez, Fırat Enver; Uz, Volan Emre
The burden of highly subsidized public transportation services necessitates careful planning of operations and resource management. Traditionally, planning involves utilizing costly and cumbersome methods to collect historical data on passenger behavior and travel demand. This study aims to contribute to the use of passive data in the public transportation planning processes by utilizing smart card data from a one-weekday to estimate the potential mode shifts from bus transits following the commencement of the extended metro line in Narlıdere, İzmir. For this purpose, first, the trip chaining algorithm, widely used in literature, is used to estimate the alighting location of passengers. Then, the competitive bus routes are determined, and this process is accompanied by other algorithms developed to create alternative scenarios where the passengers repeat their trips by utilizing the metro. Finally, the mode shift behavior of the passengers is estimated by employing travel time saving, which is calculated both deterministically and considering the passenger’s travel convenience. As a result, 39 bus routes are identified operating inside the service area of the metro extension. Sixteen of them are selected for further analysis based on their competitiveness, which is higher than 55%. The results showed that almost 30 to 55% of the passengers on the competitive bus routes favor the metro opening by lowering travel time and/or increasing travel convenience. Additionally, out of 30,779 passengers using competitive bus routes, it is either not possible or feasible for 5,517 of them to switch to the metro because 76% start and end their journeys outside the metro's service area. Furthermore, the results of the spatial analysis on travel time savings revealed that investments benefit not only those who live nearby but also those who live further away. This emphasizes the significance of enhancing public transportation services, which promotes convenience and accessibility in mobility. Lastly, it is essential to note that the outputs of this study are contingent on assumptions and that varying assumptions will alter the outcomes.
Cloning and expression of the Pseudomonas sp KE38 extra-cullular protease gene in E.coli
(01. Izmir Institute of Technology, 2023-05) Bozlak, Esma Nur; Arslanoğlu, Alper
Proteases are enzymes that hydrolyze proteins into smaller pieces by breaking the peptide bonds. Protease enzyme is produced by all living things on Earth. Pseudomonas sp. KE-38 is a cold adapted bacterium isolated from soil at high altitude in Erciyes mountain, Kayseri. The purpose of this thesis was to clone the cold-active extracellular protease gene from Pseudomonas sp. KE-38, partial purification and characterization of the extracellular protease enzyme. The partial sequence of protease gene from Pseudomonas sp. KE-38 was analysed. The estimated size encoded by this gene after sequence analysis was 105 kDa. However, the size of this enzyme that was purified in this thesis was found to be approximately 50 kDa as evaluated of gelatine zymography analysis. Further investigation of the proteins in the partially purified enzyme sample by Liquid Chromatography Mass Spectrophotometry, revealed the presence of a metalloprotease enzyme with a predicted mass of 50 kDa. These results showed that the purified and characterised protease enzyme was not the same enzyme of which its gene was amplified gene was amplified and sequenced. Nevertheless, the partial characterization of the extracellular metalloprotease was performed, and the optimum temperature and pH was found to be 30°C and 8.0 respectively. The enzyme showed high activity in the presence of calcium, ethanol. The enzyme showed extremely high stability up to 25°C above this temperature; the stability dropped sharply which confirmed that the protease was a cold active enzyme and can have a potential to be used in cold temperature applications.
Multi-objective evolutionary optimization of photovoltaic glass for thermal, daylight, and energy consideration
(01. Izmir Institute of Technology, 2023-04) Taşer, Aybüke; Kazanasmaz, Zehra Tuğçe; Kundakcı Koyunbaba, Başak
As the industry has expanded and the population has increased recently, so have the World's energy consumption and greenhouse gas emissions. Buildings are responsible for almost 40% of this consumption and emissions. They should be designed following energy-efficient and sustainable strategies. One of the most practical methods for increasing building energy efficiency and reducing environmental effects is building-integrated photovoltaic systems, which use solar energy to generate electricity on-site. This thesis explores the potential of photovoltaic glass technology in an architecture studio at the Izmir Institute of Technology Campus in Izmir, Turkey. The initial part of the study uses simulation modeling and field measurements in three scenarios to test the benefits of this technology in terms of thermal and lighting energy consumption and comfort levels. Scenarios included amorphous silicon thin-film modules in three transmittance values modeled in existing windows. Research findings propose that photovoltaic glasses have the potential to balance the room's lighting loads in a range between 15.1-and 20.3%. They improved occupant thermal and visual comfort by preventing overheating and glare risks. They also decreased cooling loads. Then, the study uses a genetic optimization algorithm to explore the optimum potential of the system in terms of annual energy consumption and daylight performance. Design variables are the window-to-wall ratio (i.e., window size and location) and amorphous-silicon thin-film solar cell transmittance to generate optimum Pareto-front solutions for the case building. Optimization objectives are minimizing annual thermal (i.e., heating and cooling) loads and maximizing Spatial Daylight Autonomy. Optimized results of Low-E semi-transparent amorphous-silicon photovoltaic modules applied on the window surface show that the Spatial Daylight Autonomy is increased to 82% with reduced glare risk and higher visual comfort for the occupants. Photovoltaic modules helped reduce the room's seasonal and annual lighting loads by up to 26.7%. Compared to non-optimized photovoltaic glass, they provide 23.2% more annual electrical energy.
In silico design of chimeric peptides for infection resistant implant coatings
(01. Izmir Institute of Technology, 2023-06) Kan, İlker; Yücesoy, Deniz Tanıl; Özçivici, Engin
Tooth loss has been a widespread dental problem affecting patients of various ages. Replacement of lost teeth with implants is a common practice for managing tooth loss due to their mechanical properties and natural-looking aesthetics. One of the persistent problems associated with dental implants is the risk of infection (periimplantitis) which can occur when bacteria colonize the implant surface leading to inflammation and tissue damage with an eventual implant failure. Infection-resistant antimicrobial coatings have been one of the promising solutions to combat implant infections. The purpose of this study was to design functional chimeric peptides using antimicrobial peptides and hydroxyapatite binding peptides in order to provide an antimicrobial effect to hydroxyapatite-coated titanium dental implants. For this purpose, since titanium implants coated with hydroxyapatite show long-term biocompatibility, chimeric peptides that can provide antimicrobial resistance have been designed by considering antimicrobial peptides in addition to these coatings. Computational analysis, solubility analysis, secondary structure analysis, and conformational change analysis were performed to examine the ability of these formed chimeric peptides to retain their antimicrobial properties. Promising candidates obtained from secondary structure analysis and solubility analysis were examined to preserve their structure and stability by performing conformational change analysis, and the most suitable candidates were decided. Although the results give candidates computationally according to the analysis, these candidates should be confirmed experimentally. When the results from the computational analysis are validated by the experimental analysis, it will set the standard for antimicrobial chimeric peptide design.
Elucidation of Lysosomal Cathepsin A in the regulation of autophagy
(01. Izmir Institute of Technology, 2023) Yanbul, Selman; Seyrantepe, Volkan
Lysosomal Cathepsin A (CathA) is a multifunctional enzyme with independent catalytic and protective functions. It has a serine carboxypeptidase activity in acidic pH conditions for the degradation of short bioactive peptides that are vasoactive peptides including endothelin-1, angiotensin-I, bradykinin and neuropeptides including oxytocin and substance P. Lysosomal CathA enzyme also forms a lysosomal multienzyme complex (LMC) with α-neuraminidase (Neu1) and ß-Galactosidase (ß-Gal) enzymes to protect them from hydrolytic degradation in lysosomes and due to its protective function. Genetic defects in the lysosomal CathA enzyme causes a rare lysosomal storage disorder, Galactosialidosis (OMIM #256540), with secondary deficiencies of Neu1 and ß-Gal enzymes. Catalytically inactive Cathepsin A knock-in mouse model, CathAS190A has point mutation in the active catalytic site which serine was replace with alanine amino acid. Accumulation of short bioactive peptides has been reported in previous studies in different tissues of the CathAS190A mouse model. In this thesis study, investigation the role of the lysosomal CathA enzyme in the regulation of autophagic flux in neuroglia and fibroblast cell lines derived from CathAS190A mice was aimed. For this aim; RT-PCR, Western Blot and Immunocytochemical analyses were for performed for autophagy markers. Thesis study results have exhibited that catalytically deficient CathA causes the impairment in autophagic machinery with secondary accumulation of autophagic substrates and alterations in the expression of the autophagy marker genes. Accumulation of the short bioactive peptides due to the catalytically inactive CathA enzyme may be related to to impaired autophagic flux. Autophagy-inducing Rapamycin and Starvation treatment conditions may restore the impaired autophagic flux due to catalytically inactive CathA enzyme with the clearance of accumulation of secondary autophagic substrates.
Determination of flood risk areas and development of mitigation strategies in Kabul River Basin, Afghanistan
(01. Izmir Institute of Technology, 2023-06) Barez, Esmayel; Tayfur, Gökmen; 01. Izmir Institute of Technology
Flooding is a devastating and natural catastrophe to population, environment, and socioeconomic development globally. Floods occur frequently in Afghanistan, especially in Kabul River Basin. Many geographical techniques have been established in recent years to map, predict and model flood risks. This research investigates identification of flood-prone zones and development of mitigation measures in Kabul River Basin. First, in this research, GIS and MCDA methodology was applied to generate flood risk map. Also, AHP method was applied to determine the best weights to be assigned to the factors that influence risk of flooding. A flood risk map of KRB was produced using 10 conditioning criteria; soil, rainfall, lithology, LULC, TWI, NDVI, distance to stream channels, curvature, elevation, and slope. Based on the weighted overlay integration of GIS-AHP technique, KRB was grouped into four flood vulnerability zones; very low, low, high, and very high. Generated flood risk map indicates a good match with the flood risk areas and location of past floods in the basin over recent years. Second, 2D HEC-RAS model and flood frequency analysis were developed for different scenarios to simulate the flow of river and to develope mitigation measures with a 500- year return period in the main river of Kunar and the lower Kabul sub-basin. Manning's n values were used to calibrate HEC-RAS model, and past flood events applied for validation. Flood mitigation strategies, including river restoration, construction of dam, and reservoir improvement were proposed on the Kunar and lower Kabul sub-basin. Keywords: Flood Inundation Map, Hydraulic Modelling, ArcGIS-MCDA.
Process parameters and mechanical properties of geopolymer glass foam structures
(01. Izmir Institute of Technology, 2020-12) Polat, Dilan; Güden, Mustafa; 01. Izmir Institute of Technology
The effects of waste-glass powder particle size (23 and 72 μm), solid/liquid ratio (S/L=1, 1.5 and 2) and aluminum foaming agent content (2-20 wt%) on the expansion behavior of geopolymer slurries were investigated experimentally. Geopolymer slurries were prepared using an activation solution of NaOH (8M) and sodium silicate (10% NaOH, 27% SiO2). The expansions and temperatures of the slurries were measured in-situ using a laser distance meter and a thermocouple, respectively. Few geopolymer foams were sintered at 600, 700, 725 and 750 °C. The compression strengths and thermal conductivities of foam samples were also determined. The expansion of slurries continued until the temperature increased to 85-90 °C. At this temperature, the slurry evaporation; hence, increased S/L ratio limited both the hydrogen release rate and geopolymerization reaction. As the content of Al increased, the final foam density decreased, while the coarse powder slurries resulted in lower densities (240-530 kg m-3) than the fine powder slurries (280-530 kg m-3). Three crystal phases, muscovite, sodium aluminum silicate hydrate and thermonitrite, were determined after the geopolymerization. The muscovite formation was noted to be favored at higher S/L ratios. The partial melting of glass particles started after ~700 °C, while sintering above this temperature decreased the final density. The reduced density above 700 °C was ascribed to the release of carbon dioxide by the decomposition of thermonitrite. Both the compressive strength and thermal conductivity of geopolymer and sintered foams increased at increasing densities and were shown to be comparable with those of previously investigated geopolymer and glass foams. The geopolymer foams sintered at 750 °C exhibited the lowest density and the highest compressive strength.

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