Akademik Çıktılar

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1-octanol dehydration on Al2O3-SiO2 catalyst
(Izmir Institute of Technology, 2021-12) Uçar, Beyza; Şeker, Erol; 01. Izmir Institute of Technology
Bu çalışmada, heterojen asit katalizörün 1-oktanol dehidrasyonunda, ürün dağılımına etkisi araştırılmıştır. Kullanılan katalizörler sol-jel yöntemiyle sentezlenmiştir. Sentezlenen katı asit katalizörler ağırlıkça farklı oranlarda (25%-75%, 50%-50% ve 75%-25%) Al2O3-SiO2 katalizörleriydi. Ayrıca, sentezlenen Al2O3-SiO2 katalizörlerin kalsinasyon sıcaklıkları 500 ̊C, 700 ̊C ve 900 ̊C idi. Bu çalışmanın amacı, Al2O3-SiO2 katalizörlerin asidik-bazik özelliklerini ve birincil alkol dehidrasyonu üzerindeki etkisini anlamaktır. Kullanılan bütün katalizörler için dehidrasyon reaksiyonu 150 ̊C ve reaksiyon süresi 4 saat olarak devam etti. Ürünler ve var olan miktarı GC-MS analizi ile belirlenmiştir. Buna ek olarak, katalizörlerin asidik ve bazik özellikleri NH3-TPD ve CO2-TPD analizleri ile açıklanmıştır. Ayrıca katalizörlerin kristalografisi, XRD sonuçlarına göre belirtilmiştir. Bu çalışma, katalizörlerin bileşiminin ve uygulanan kalsinasyon sıcaklıklarının, reaksiyon yollarını etkileyen asidik-bazik kuvvetleri üzerinde etkili olduğunu ortaya koymuştur. Bunun sonucunda ürün dağılımı ve genel dönüşüm değerlendirilmiştir. Ana ürünler oksalik asit 2-etilheksil tetradesil ester, oktil eter, esterler (Formik asit, oktil ester, Asetik asit, oktil ester ve Heptanoik asit, oktil ester) ve oktanal idi. Ürün dağılımının esas olarak Al2O3-SiO2 katalizörlerinin asidik ve bazik güclerine bağlı olduğu gösterildi.
Adolescents' uses of urban public spaces: A case in Menderes (Izmir)
(01. Izmir Institute of Technology, 2021-12) Şahin, Fatma Nur; Şenol, Fatma; 01. Izmir Institute of Technology
The study examines how adolescents use urban public spaces and what kind of urban spaces they want. It details the social and physical environmental characteristics affecting the uses of public spaces and user perceptions of 15-18 years old students in the central settlement of Menderes District of the Izmir Province. This is a critical subject needed for an investigation. Public spaces are one of the common areas for the socialization and personal development of adolescents. Various studies have determined that adolescents' use of public spaces (e.g., streets, squares, parks) has differences from the general public use. Adolescents use public spaces to improve their relations with their surroundings, socialize with their peers and participate in various activities. They participate in friend-group activities, such as talking, chatting, resting, having fun, spending time with friends, playing games, meeting, hanging out, and so on. Although there is an increasing number of studies abroad, there is an important literature gap about characteristics affecting adolescents' use of public spaces in Turkey. In addition to many social characteristics (such as meeting with peers, feel free), adolescents' perceptions of the physical characteristics of the built environment (such as being an accessible, natural, and clean environment) are some of the essential characteristics that shape their use of public space. For this reason, the needs of adolescents must meet to achieve the necessary gains to complete their social development healthily and become well-developed adults in the future. However, studies on spatial possibilities are lacking that allow the realization of activities that meet these needs. This study aims to determine the social and physical characteristics affecting adolescents' use and perceptions of public spaces. This thesis developed as research about 15-18 years old high school students about their preferences and usage experiences in urban public spaces in the city center of Menderes District of İzmir. The differences in the uses and preferences of adolescents in using public spaces should reflect in the physical designs and plans of residential areas. Finally, it develops recommendations and strategies for the physical design of the public open spaces for adolescents.
Analysis of fingerprint matching performance with deep neural networks
(01. Izmir Institute of Technology, 2022-03) Göçen, Alper; Erdoğmuş, Nesli; 01. Izmir Institute of Technology
Fingerprints are unique biometric properties for each person. In the literature and industry, they are widely used for identification purposes. Collecting biometric datasets is a tedious work since it is not possible without the owners’ consent, and existing fingerprint datasets are either not sufficient to use in deep learning tasks by means of size or most of them are kept private to the collectors’ use. This increases the need of synthetic fingerprint images and their use in a variety of tasks especially for training deep learning models. In this study, the performance of a CNN architecture named Finger ConvNet[1] is compared to well-known networks and the question of whether a mixed dataset consisting of synthetically generated and real fingerprint images can reach a performance close or equal to ones having only real images is discussed. As a result of experiments, it is shown that the number of real images in the dataset is an important factor and that the performance of the mixed dataset was less than the one having only real images proposed in the referred study.
An analysis of the impact of the exchange rate pass-through (ERPT) to construction cost index and housing unit prices in Turkey
(01. Izmir Institute of Technology, 2021-07) Lağap, Umut; Kale, Serdar; 01. Izmir Institute of Technology
After the high-speed globalization attack, the interrelations between countries have increased significantly, and local economies have become vulnerable to global economic developments. Despite the successful monetary policies in the 2000s, the Turkish Lira has severely depreciated against foreign currencies in the last decade. Thus, the exchange rate pass-through (ERPT) to domestic prices and its relationship with other macroeconomic variables has become a hot topic for governments and scholars in the literature. However, this pass-through effect on the Turkish Construction Industry and the Housing Market is minimal, although they play a pivotal role in the Turkish economy. With Vector Autoregression (VAR) models analyzing the collected monthly data between 2010 and 2020, this study reveals (1) the ERPT to housing unit prices in Turkey (hup1) and Istanbul (hup2), (2) the change in this pass-through effect during economic stabilization, and fluctuation in the Turkish economy. Moreover, this thesis uncovers (3) the ERPT to Construction Cost Index (cci1) and its material component (cci2) between 2015 and 2020. As a result of Variance Decomposition (VD) and Impulse Response Function (IRF), the housing mortgage rate's (hmr) effect on hup2 is much more significant than its effect on hup1 in the first two years. However, there is no significant difference between the nominal exchange rate's (exr) effects on these prices in the same period. Besides, the effects of hmr and exr diminished during economic stabilization. Moreover, the ERPT to cci1 is greater than the ERPT to cci2 at the end of the first year.
Application of graph neural networks on software modeling
(01. Izmir Institute of Technology, 2020-12) Leblebici, Onur Yusuf; Tuğlular, Tuğkan; Tuğlular, Tuğkan; Belli, Fevzi; 01. Izmir Institute of Technology
Deficiencies and inconsistencies introduced during the modeling of software systems can cause undesirable consequences that may result in high costs and negatively affect the quality of all developments made using these models. Therefore, creating better models will help the software engineers to build better software systems that meet expectations. One of the software modelling methods used for analysis of graphical user interfaces is Event Sequence Graphs (ESG). The goal of this thesis is to propose a method that predicts missing or forgotten links between events defined in an ESG via Graph Neural Networks (GNN). A five-step process consisting of the following steps is proposed: (i) data collection from ESG model, (ii) dataset transformation, (iii) GNN model training, (iv) validation of trained model and (v) testing the model on unseen data. Three performance metrics, namely cross entropy loss, area under curve and accuracy, were used to measure the performance of the GNN models. Examining the results of the experiments performed on different datasets and different variations of GNN, shows that even with relatively small datasets prepared from ESG models, predicts missing or forgotten links between events defined in an ESG can be achieved.
Architecture, community and the Aga Khan Award for Architecture
(01. Izmir Institute of Technology, 2021-07) Keser, Elif; Erten, Erdem; Yücel, Şebnem; 01. Izmir Institute of Technology
This thesis aims to understand/explore how architecture can assume social responsibility and offer solutions to social problems by focusing on projects awarded by the Aga Khan Award for Architecture (AKAA). Unlike many major architecture awards, the AKAA prioritizes social contribution and the projects selected by the award features architects taking social roles other than simply being the designer. While examining the social responsibility of architecture, the thesis explains the alternative roles that the architect can take on regarding certain themes. The first chapter investigates the history of "community-oriented architecture" and its examples in the literature. The second chapter focuses on the projects awarded by the AKAA with reference to the contributions of architecture to social development. From the first award period to the last (1980-2019), 124 projects were examined and 8 examples suitable to the scope of the thesis were selected. When selecting these examples, three main themes were determined (using parameters such as economic resources, relations with local government, organization, community education, etc.): "Participatory Architecture", "Urban Upgrading and Community Development", "Historical Restoration and Socio-Economic Revival". Under these themes, subheadings were created according to the alternative social role assumed by the architect. The extensive archive of the Aga Khan Award for Architecture was used for the necessary documents such as detailed information about the projects, technical reports, jury reports.
Assessment of the 2018 Turkish seismic regulations unreinforced masonry construction specifications through a case study structure
(01. Izmir Institute of Technology, 2020-12) Turan, Egecan; Dönmez, Cemallettin; 01. Izmir Institute of Technology
The new release of the seismic regulation in 2018 resulted in major changes in masonry structures' design approach. It changes from the allowable stress design method to the ultimate strength design method. Also, the effect of vertical earthquake component, which was not considered, is included in the analysis combinations. The seismic risk is started to be defined by parameters determined according to the geographical coordinates of the building that is considered. The presented study is intended to investigate the impact of the listed changes on unreinforced masonry design. A case study building is utilized for this purpose. It is designed to satisfy the TER-2007 requirements and re-evaluated considering the TER-2018 requirements. The results show that the building did not have sufficient capacity, according to the 2018 earthquake regulation. Almost all the walls were beyond their capacities. The same structure has been analyzed by nonlinear static analysis (pushover analysis) as well. According to the nonlinear analysis results, performance assessment was made per the 2018 earthquake regulation and FEMA356. The performance evaluation by nonlinear static analysis using TER-2018 and FEMA356 demands, satisfies the life safety performance level for FEMA356 and TER-2018.
Atmospheric effects on short term wind power forecasting
(01. Izmir Institute of Technology, 2021-07) Kalay, Yüksel; Bingöl, Ferhat; 01. Izmir Institute of Technology
Wind power all over the world are being popularizing unlike decrease in conventional sources due to environmental issues. However, power acquired from wind is not stable during day and night, which means that intermittent due to nature of the source. Forecasting in wind power plant is very challenging compared to forecasting of production of conventional power plant. Although there are many robust and site-specific models in order to forecast wind power accurately, decrease of deviation in wind power forecasting by using statistical, physical and hybrid models is still open to new approaches. In this study, four different forecast models based numerical weather prediction (NWP) models for three different wind farms which have different atmospheric conditions are examined to improve wind farm-based power forecasting. For this purpose, wind power forecasting of the providers was categorized based on atmospheric effects, which are site temperature and turbulence. Results have been compared with real time power production from wind turbine supervisory control and data acquisition (SCADA) system. Afterwards, new method based on selecting best provider for specific condition was developed by considering atmospheric effects on power forecasting. It should be noted that the method is an engineering approach, not a new forecast model. In many cases, newly developed method has succeeded to outperform in comparison to results belonging to forecast providers. Hourly and daily wind power forecasting that have significant role in electricity market has been improved for selected wind farms by the help of an engineering approach used in this study. Same method is also implementable to another wind farm if required inputs exist.
B92 based quantum key distribution with faint pulsed laser
(01. Izmir Institute of Technology, 2021-12) Mutlu, Görkem; Ateş, Serkan; Çakır, Özgür; 01. Izmir Institute of Technology
In quantum key distribution (QKD), photons are used to share the key between the transmitter and receiver, and in principle, single photon sources should be used to create a secure communication channel. Nowadays, attenuated laser sources are used in many studies. While it is practical to use attenuated laser pulses for QKD system, it poses many safety issues due to the possibility of multiple photons in the laser pulses. In addition, the key rate is waived to increase the level of security. However, the use of single photon sources is not as easy and practical as using attenuated laser sources. Today, studies of single photon sources to be used for QKD continue. In order for these single photon sources to be used actively, a photon source that operates at room temperature, operates in a wide band-gap range for different areas of use (underwater, optical fiber-based and free space) and can be excited at high speed is required. Since hBN defect centers are a material that can produce single photons at room temperature and have a wide band gap, it seems very ideal for these studies. In this thesis, studies have been carried out on the realization of the protocol, which is a part of QKD, with solid-state materials that produce single photons. In the studies, a key was produced with a faint pulsed laser. Also, data is encrypted using the key of the transmitter. Then the data is successfully decrypted with the key measured by the receiver.
Bending behavior of hybrid fiber reinforced concrete beams
(Izmir Institute of Technology, 2020-12) Aloui, Sarra; Saatçi, Selçuk; 01. Izmir Institute of Technology
Fiber reinforced concrete is widely used in various applications in concrete members. In this study, effect of fiber hybridization, using different types of fibers in concrete mix, on the bending behavior of concrete beams was investigated. For this purpose, eight beam specimens, 2500x500x50 mm in dimension, were cast in pairs with four different steel fiber content. One of the two specimens with the same steel fiber content had additional Polyvinyl Alcohol (PVA) fibers. The specimens were first tested under three-point bending. After these tests, failed specimens, which had a single crack at the midspan, were broken into two halves and the half with no visible damage was tested again under four-point loading to obtain the behavior for a constant moment region.The ultimate strength and the load-displacement behaviorwas investigated for each specimen. It was seen that fiber hybridization obtained by addition of PVA had an adverse effect for three-point bending tests. Specimens with additional PVA fibers had a lower ultimate load and deflection capacity compared to specimens with only steel fibers. However, fiber hybridization had a positive effect for same specimens under four-point bending test. It was concluded that hybridization of steel and PVA fibers had a positive effect on the bending behavior for loading conditions that result in a uniform moment distribution. However, for cases where a single crack dominates the behavior, such as a three-point bending case, hybrid fibers were not as effective or even had an adverse effect.
Bilayer chitosan/zein based nanofibers for antimicrobial wound dressing application
(01. Izmir Institute of Technology, 2021-12) İskeçman, Nilsu; Tıhmınlıoğlu, Funda; 01. Izmir Institute of Technology
Nowadays, modern functional wound dressings have become prominence due to their biocompatible, biodegradable, and non-toxic nature and ability to mimic ECM of skin. To enhance their mechanical and prolonged cumulative release of drugs in media, environmentally friendly inorganic nanofillers are preferred. Recently, halloysite nanotubes (HNTs) which is a new class of inorganic filler are using to improve mechanical properties and thanks to their tubular structure various agents encapsulated into these tubes to make drug release more controlled. In this thesis, it was aimed to fabricate and characterize bilayer wound dressing by using Zein-Vancomycin loaded HNTs nanofibers as upper layer to mimic ECM of skin and provide antibacterial protection and chitosan sponge as bottom layer to absorb the excess exudates of wound, provide gas transmission and facilitate the migration of inflammatory and fibroblast cells into the healing wounds. The morphology of nanofibers and encapsulation efficiency of HNTs are optimized to achieve similar homogeneous fiber structure with skin tissue and controlled release of Vancomycin drug. Chemical interaction between Vancomycin-HNT and Zein-HNT were characterized by FT-IR. The surface charge differences of HNTs by encapsulating drug into tubes was determined by zeta potential analysis. The weight loss percentage of nanofiber with the addition of HNTs into zein media was characterized by using thermogravimetric analysis (TGA). Bilayer sponges were characterized by SEM, FT-IR, porosity, mechanical properties, contact angle, water vapor transmission rate, swelling, degradation, cumulative drug release and their kinetics and antimicrobial activity analyzes. The diameter of drug loaded HNT-Zein nanofibers were found 202,7±0,05–225,2±0,06 nm which is in the range of native skin collagen fibril (50-500 nm) than can mimic ECM. The water vapor permeability of the wound dressings is between 2833 and 2490 g/m2day which is found in the appropriate range for wound healing. Bilayer dressings reached 78% cumulative release at the end of 14 days and the release medium showed antimicrobial activity against E. coli and for S. epidermidis. In conclusion, the developed drug-loaded bilayer mat has been found as a potential candidate for wound dressings applications to treat the chronic infections.
Bioinformatic analysis and biostatistical modelling of genetic interactions between microbiota and host
(01. Izmir Institute of Technology, 2020-12) Musa, Farid; Sezgin, Efe; 01. Izmir Institute of Technology
Advances in genome sequencing technology have revolutionized the study of microorganisms. Recent genome-wide association studies (GWAS) on gut microbiota revealed fascinating discoveries about the effect of microbiota on our health. In this thesis, Drosophila Melanogaster samples were used to investigate the associations between the host's genotype and microbiota. The meta-analysis of microbiota data was performed using PhyloMAF, a novel, and comprehensive microbiome meta-analysis framework. The resulting microbial abundance tables were analyzed using alpha and phylogenetic beta bio-diversity metrics, which were used in the microbiome GWAS study. Significant variant associations were further analyzed in the post-GWAS analysis. The results of our study show that several genomic variants are significantly associated with bio-diversity estimates. Among identified variants, few were found to be associated with more specific phenotypes. Particularly, the gene involved in folate transport and linked to folate malabsorption was found to be associated with Proteobacteria. The latter for its part was found to be one of the primary phyla containing the highest number of genes responsible for de-novo folate synthesis. Similarly, the fly gene related to immune function with the human homologous gene linked to the inflammatory gut disease was found to be associated with the Acetobacter genus. This genus based on the literature survey was found to be associated with an immune deficiency in a fruit fly. In summary, this research revealed captivating findings of genetic factors associated with fruit fly microbiota. The limitations and future directions were stated in order to provide the basis for future prospective studies.
Biolubricant production over sulfated TI-SBA-15 and TIO2-SIO2 based mesoporous catalysts
(01. Izmir Institute of Technology, 2022-05) Özperçin, Tuğçe; Yılmaz, Selahattin; 01. Izmir Institute of Technology
Production of ecofriendly biodegradable lubricants from vegetable oils is an attractive alternative to petroleum derived lubricants for environmental protection. This study presents an investigation for the production of biolubricants via ring opening reaction of epoxidized soybean oil using the mesoporous solid acid catalysts. SO4/SBA- 15, SO4/Ti-SBA-15, SO4/TiO2-SiO2 and SO4/La-TiO2-SiO2 catalysts were prepared and characterized. In addition, effect of increasing titanium content on SO4/Ti-SBA-15 (Si/Ti: 10, Si/Ti: 6) and effect of sulfation source (ammonium sulfate and chlorosulfonic acid) on Ti-SBA-15 and La-TiO2-SiO2 properties, activities and stabilities were studied. Activity and stability of all the catalysts were tested in the ring opening reactions of epoxidized soybean oil with 2-propanol at 80 oC with 10/1 alcohol-epoxide mol ratio. After determination of the two most stable and active catalysts, reactions were also performed with 2-ethylhexanol at 100 oC with 6/1 alcohol-epoxide mol ratio. Products were analyzed by titration, FTIR and H-NMR. Also, thermal stability and low temperature behavior of products were determined by thermogravimetric analysis and differential scanning calorimetry. Prepared catalsysts had mesoporous structure and stronger acid sites by attachment of sulfate groups The catalysts showed a serious leaching when they were sulfated with ammonium sulfate. On the other hand, chlorosulfonic acid treatment enhanced significantly stability of catalyst. Furthermore, increasing of titanium content and sulfation with chlorosulfonic acid increased the acidity of catalysts compared to ammonium sulfate. The SO4/Ti-SBA-15-6(CS) catalyst (Si/Ti:6 mole ratios and chlorosulfonic acid sulfated) was found as the most stable and active catalyst. It provided 62 % (12 h) and 90 % (18 h) conversion in the reactions with 2-propanol and 2-ethylhexanol, respectively. All products were found as thermally stable up to 300 oC showing that ring opening reaction did not affect thermal stability. Nevertheless, it affected positively low temperature properties and better low temperature properties were obtained from the products of reactions with 2-ethylhexanol. However, its influence on the products obtained from 2-propanol was not prominent.
Blackhole attacks in IoT networks
(01. Izmir Institute of Technology, 2020-12) Sokat, Barış; Ayav, Tolga; Ayav, Tolga; Erten, Yusuf Murat; 01. Izmir Institute of Technology
IoT technologies are very popular today, and they are used in almost every field. Therefore, the number of IoT devices used is increasing day by day. Like every field in computer networks, security is quite important in IoT networks. However, the resource-constrained nature of IoT devices makes the study of security measures for IoT networks very challenging. In the literature research conducted before this thesis study, it was seen that it can perform a wide variety of RPL-based attacks on IoT networks. One of these attacks is the blackhole attack. Although the black hole attack is functionally simple, the damage it causes in the network can be extremely destructive. As far as it is known, in addition to the limited number of studies in this field of attack, the black hole attack used in the studies in this field has also basic features. The basic feature mentioned here is that the attacker node that will perform a black hole attack drops all the packets that come to it. When the attacker node drops all incoming packets, it causes the topology to change in the network, the number of control messages to increase and the attacker node to be isolated from the network in a short time. However, blackhole attack can be combined with different attacks. Therefore, in this thesis, the node that will perform the black hole attack is designed to allow control messages to pass, while dropping all other packets. Here, it is aimed that the attacker node remains on the network for a longer time. As a result, as long as the attacker node is active, it will be able to drop more packets and the number of control messages in the network will be controlled since the topology does not change. With the black hole attack developed as a result of the simulation tests, the number of control messages released in the network was taken under control and it was observed that the attacker node could remain in the network throughout the simulation period. Thus, the effect of different types of black hole attacks on the network that can be developed has been revealed.
Blockchain based context aware access control structure implementation for security of internet of things system
(01. Izmir Institute of Technology, 2022-03) Kul, Aslı; Demirörs, Onur; Erten, Yusuf Murat; 01. Izmir Institute of Technology
Nowadays, Internet of Things (IoT) devices, which have started to be included in our lives with the developing technology, are one of the popular working topics. While they are a means of transporting many important data in terms of usage areas, IoT devices have brought security concerns due to their being a new technology and technical limitations. The use of standard access control algorithms is insufficient for IoT environments due to their complexity and dynamism. In this study, considering the importance of sensitive critical data carried by IoT environments, Context Aware IoT Rule Based Access Control Algorithm, which is a proposed algorithm to ensure the security of interaction with IoT environments, is aimed to be integrated and used to create a reliable IoT environment by taking advantage of the security promising Blockchain technology. It is due to the use of distributed and cryptography methods that are widely used today.
Butyl esters production from canola oil over heterogeneous base catalysts
(01. Izmir Institute of Technology, 2021-03) Akın, Oğuzhan; Şeker, Erol; 01. Izmir Institute of Technology
In this study, transesterification reaction of canola oil with butanol over calcium oxide alumina catalyst was investigated with varying butanol:lipid molar ratios, catalyst amount and reaction time. Catalysts were prepared with the single step sol-gel method, and the activity of synthesized catalysts were investigated for two different forms of catalysts as powder and structured form. In the case of powdered catalysts, at butanol:lipid molar ratios of 9 and 24 with 6 wt% of lipids as catalyst amount, leaded 32% and 45% butyl esters yield in 1 hour. On the other hand, ~70% butyl esters yield has obtained at butanol:lipid molar ratios of 48 and 60 for the reaction time of 1 hour, while 89% yield had achieved when the reaction lasted for 4 hours at butanol:lipid molar ratio of 48. The necessity of mild basic strength and high butanol:lipid molar ratio was found to obtain high butyl esters yield. At high butanol lipid ratios of 48 and 60, it was observed that glycerolysis reaction occurs and promotes reverse transesterification reactions in first 30 minutes of the experiments. In the case of structured catalysts, lower butyl esters yields than powder catalysts were obtained, yet they eliminated the need for catalysts separation step in the experiments. Reusability tests showed that catalyst activity has decreased due to calcium ion leaching in the first hour of reaction and kept its activity constant for the rest of the reaction.
A case study: Site-specific seismic response analysis for base-isolated building in Düzce
(01. Izmir Institute of Technology, 2020-12) Eren, Volkan Gökçe; Ecemiş Zeren, Nurhan; 01. Izmir Institute of Technology
Under seismic loads, soil-structure interaction, and its effect on performance of pavements is more important today. Turkey is located in one of the most active seismic zones in the world. In the past, many destructive earthquakes happened in Turkey. The fact is that due to frequent earthquakes in the future, we may suffer a significant loss of life and property. Therefore, it has been necessary to minimize demolitions by conducting soil behavior analysis for each site. To design buildings, bridges, and other structures with base-isolators according to performance, it is necessary to carefully evaluate the long-term ground motions, especially in determining the earthquake ground motion. In these evaluations, empirical and theoretical methods to predict the response spectrum, considering and analyzing the effects of the near-fault, scaling the spectrum for different damping ratios, and simulation of long-term ground motions time-history constitute an essential place. It is necessary to determine the principles required for modifying the design spectrum in the long-period boundaries. The regulations are required to simulate long-period ground motions in the time-history and the necessary rules for selecting and scaling the earthquake ground motion records by considering the long-period effect. In this thesis, commonly used approaches in national and international regulations in defining the earthquake effect were evaluated, and the recommended earthquake levels for structures within the Düzce city in Turkey are explained. While evaluating the earthquake hazard in the study area, the general geology, tectonic features, ground conditions, and existing fault systems of the region were considered. For the study area, besides the classical hazard spectra, hazard curves for different spectral ordinates that allow the calculation of probabilistic seismic hazard maps and spectral coordinates for various periods are presented. Earthquake records were selected according to these spectra, and nonlinear analyses were made by simulating earthquake data for structural analysis. Turkey Earthquake Building Regulations (TBDY, 2018) to determine the seismic design spectrum is considered.
Cell patterning with magnetic manipulation
(01. Izmir Institute of Technology, 2020-12) Çağan, Melike; Özçivici, Engin; 01. Izmir Institute of Technology
Tissue engineering is a biomedical engineering field that provides solutions to restore, maintain, improve or replace tissues or whole organs. The main goal tissue engineering is to overcome the restrictions of existing treatments that are based on organ transplantation. Cells and biomaterials can be used to form functional tissues and organs. Actually, the goal is to produce structures that resemble and mimic the real tissues. One of the useful mimicking technique is cell patterning. Cell patterning is a technique that provides cell clusters are located at a proper position for function of tissues. Some of the patterning techniques uses cell adhesion ligands, optical tweezers, acoustic tweezers, dielectrophoresis and magnetic force. In addition to the advantages of all these techniques, there are also disadvantages. However, Magnetic force-based cell patterning techniques provide excellent advantages such as low adverse effects to cell. Magnetophoresis is one of the magnetic force-based cell patterning technique that forms cell patterns without labeling cells in a short time using the principle of movement of the cells to lower magnetic field region in a paramagnetic medium. In this study, a cell patterning system was used to form cell patterns via magnetophoresis. Results showed that cell patterns were formed in different shapes in a short time and they maintained integrity even if magnetic force was removed.
Ceramic microfiltration membrane design towards oil removal in metal industry wastewater streams
(01. Izmir Institute of Technology, 2020-12) Eren, Muhammet Şakir Abdullah; Çiftçioğlu, Muhsin; 01. Izmir Institute of Technology
Increasing water scarcity is an important threat to the whole world. The use of too much water during the production processes and the insufficient level of reuse of this water and the increasing quantities of oil containing waste generated in many industrial activities cause dangerous consequences for the environment. Highly concentrated oil-inwater emulsions are very harmful for aquatic life, soil, atmosphere and human health. Traditional treatment methods are not effective in the removal of emulsified oil droplets which have less than 20 µm of droplet size. Ceramic micro/ultrafiltration membranes have been explored and developed in recent years due to their superior advantages in oil containing water treatment/purification. The aim of this MSc study was to produce tubular ceramic supports and microfiltration membranes for the removal of oil from stable oil in water emulsions used as metal cutting fluids. The prepared metal cutting fluids were fed to the crossflow filtration system and the effects of experimental parameters such as transmembrane pressure (TMP), crossflow velocity (CFV) and oil content on membrane performance/permeate flux were investigated. The single/double layered coatings on the support surfaces were formed in the preparation of the microfiltration membranes by using stable 0.4 µm α-alumina suspensions. The 1 layer and 2 layers containing microfiltration membranes were heavily fouled and very low permeate fluxes were obtained in an hour of treatment. This was attributed to the formation of a thin oil layer on the microfiltration membrane surfaces. The reduction of the total suspended solids (TSS) and turbidity were determined as ~100 %. A stable permeate flux with a lower extent of membrane fouling and concentration polarization was obtained with 1% oil content and the support membrane and TMP=2 bars.
Characterization of designed novel cytochrome P450 for industrial biocatalysis
(01. Izmir Institute of Technology, 2020-12) Sakallı, Tuğçe; Sürmeli Eraltuğ, Nur Başak; 01. Izmir Institute of Technology
Biocatalysts are increasingly applied in chemical synthesis due to their high level of regioselectivity and enantioselectivity. P450s are important biocatalysts due to their ability to hydroxylate unactivated carbon atoms using molecular oxygen. P450s catalyze monooxygenation reactions by using nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) as electron donor and electron transfer proteins. P450s can also utilize hydrogen peroxide (H2O2) instead of NAD(P)H and redox partners through a H2O2-shunt pathway. However, P450s are inefficient in oxygenation reactions with H2O2. Thermophilic enzymes demonstrates high stability at different temperatures, pH and organic solvents, so it is expected to increase implementations of enzymes. CYP119 is an acidothermophilic P450 from Sulfolobus acidocaldarius. In our laboratories, directed evolution was used to create improved mutants of CYP119 with higher oxidation activity when using H2O2. T213R/T214I CYP119 was such a variant. The aim of the study is investigations of T213R/T214I CYP119 whether it is a stable and efficient biocatalyst for selective oxidation of hydrocarbons, which does not require expensive cofactors and electron transfer proteins or not. T213R/T214I CYP119 was expressed and isolated under optimized conditions. Peroxidase activity of T213R/T214I CYP119 was tested and compared to wild type (WT) CYP119. Characterization of T213R/T214I CYP119 shows higher peroxidation activity of enzyme for Amplex® Red, guaiacol and ABTS and epoxidation of enzyme for styrene substrates compared to CYP119. T213R/T214I CYP119 have higher affinity for progesterone and lower affinity for lauric acid. Mutations on Thr213 and Thr214 residues the active site will shed light on the design of novel CYP119 mutants in the future.

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