Mühendislik ve Mimarlık Fakültesi

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Alterations in Niban Gene Expression as a Response to Stress Conditions in 3t3-L1 Adipocytes
(Springer, 2020) Cevik, Mehtap; Gunduz, Meliha Koldemir; Deliorman, Gokce; Susleyici, Belgin
Adipocyte death is important in obesity development. Understanding and prevention of adipocyte deaths may be a molecular approach in the treatment. In the study, we aimed to understand role of Niban gene, which acts as an anti-apoptotic molecule as a response to stress conditions, in adipocytes. 3T3-L1 adipocytes were treated with different doses of linoleic acid, hydrogen peroxide and ethanol; and proliferation of the cells examined with real time monitoring iCELLingence system. Gene expression levels were measured by q-PCR. As a response to 24h 480 mu M linoleic acid treatment, Niban gene expression was found to be higher than control group (p = 0.008), whereas 24 h 90 mM ethanol treatment was determined to be lower than control group (p = 0.008). The highest value of Niban gene expression among H2O2 treatment groups was detected in 4h 600 mu M H2O2 in comparison to control group (p = 0.008). To understand role of Niban in adipogenesis, Niban gene expressions were compared between pre-adipocytes and advanced fat accumulated adipocytes and determined to be significantly different (p = 0.042). Our results suggest that Niban might be involved in stress response process in adipocytes. However, the exact molecular role of Niban needs to be investigated in further studies.
Binary Particle Swarm Optimization as a Detection Tool for Influential Subsets in Linear Regression
(Taylor & Francis Ltd, 2021) Deliorman, G.; Inan, D.
An influential observation is any point that has a huge effect on the coefficients of a regression line fitting the data. The presence of such observations in the data set reduces the sensitivity and validity of the statistical analysis. In the literature there are many methods used for identifying influential observations. However, many of those methods are highly influenced by masking and swamping effects and require distributional assumptions. Especially in the presence of influential subsets most of these methods are insufficient to detect these observations. This study aims to develop a new diagnostic tool for identifying influential observations using the meta-heuristic binary particle swarm optimization algorithm. This proposed approach does not require any distributional assumptions and also not affected by masking and swamping effects as the known methods. The performance of the proposed method is analyzed via simulations and real data set applications.
Cd Dopant Effect on Structural and Optoelectronic Properties of TiO2 Solar Detectors
(Springer, 2021) Ilhan, Mustafa; Koc, Mumin Mehmet; Coskun, Burhan; Erkovan, Mustafa; Yakuphanoglu, Fahrettin
Al/n-Si/Ti1-xO2CdxO/Al photodiodes were produced using sol-gel and spin coating methods where CdO dopant was applied on different concentrations (x = 0.0; x = 0.01; x = 0.05; x = 0.10). Cd dopant effect upon structural, optical, photodiode and electrical properties was assessed. Scanning electron microscope and energy-dispersive spectra were used in the structural investigation. Optic properties were assessed using UV-Vis spectroscopy and bandgap energies of the photodiodes were calculated which were found to be between 3.25 and 3.36 eV. Increased bandgap energy was observed with increased CdO doping rate. Photodiode properties were assessed under varying daylight illuminations. Barrier height, ideality factor, dark current, linear dynamic rate, photosensitivity, photoresponsivity of the photodiodes were calculated. Electrical properties of the Al/n-Si/Ti1-xO2CdxO/Al photodiodes were calculated where conductance-voltage and capacitance-voltage plots were obtained. Corrective conductance-voltage and corrective capacitance-voltage graphs confirm that the electrical properties of the photodiodes depend on AC signal frequency. Frequency-dependent electrical characteristics were attributed to the density of interface states which were found to be between 10(11) and 10(12). Decreased density of interface state was found for increased AC signal frequency.
Differences in Occupants' Satisfaction and Perceived Productivity in High- and Low-Performance Offices
(MDPI, 2019) Gocer, Ozgur; Candido, Christhina; Thomas, Leena; Gocer, Kenan
This paper reports the results from a dataset comprising 9794 post-occupancy evaluation (POE) surveys from 77 Australian open-plan offices. This paper specifically focuses on a sub-set of 20 offices (n = 2133), identified from ranking 10 offices each, with the least (n = 1063) and highest (n = 1070) satisfaction scores, respectively. The satisfaction scores were evaluated on the basis of seven factors (i.e., building/office aesthetics and quality, thermal comfort and indoor air quality, noise distraction and privacy, personal control, connection to outdoor environment, maintenance and visual comfort, and individual space). Using the POE survey data from 20 offices, regression analyses and two-way ANOVA tests were carried out to understand the differences in occupants' satisfaction and perceived productivity arising from open-plan offices. According to the statistically significant regression analyses results, it was identified that building/office aesthetics and quality (beta = 0.55, p < 0.001) and noise distraction and privacy (beta = 0.33, p < 0.001) were the two strongest predictors contributing perceived productivity in low-performance offices. Two-way ANOVA test results for the 10 high-performance offices indicate that the perceived productivity was strongly associated with the office's physical configuration, the employees' working experience, and the working hours at that office.
Effect of Heat Treatment on Magnetic Properties of Nanocomposite Nd-Lean Nd7Fe73b20 Ribbons
(Springer, 2021) Caglar, Seyit; Kilicaslan, M. Fatih; Atasoy, Ahmet; Tiryaki, Hasan; Erkovan, Mustafa; Hong, Soon-jik
In this work, we explored the effect of heat treatment on high boron and Nd-lean content magnetic Nd7Fe73B20 nanocomposite materials via vibration sample magnetometer (VSM), X-ray diffraction, differential thermal analysis (DTA), and scanning electron microscope (SEM). The Scherer formula was employed to estimate the effect in the crystal size of the heat treatment on high boron and Nd-lean content magnetic Nd7Fe73B20 nanocomposite materials. We heat-treated samples in different conditions to obtain optimum magnetic properties. Our high-throughput fabrication strategy allows us to elucidate the possibility of obtaining Nd-lean nanocomposite NdFeB magnet in terms of the melt-spinning. We evaluated the influence of heat treatment on the Nd-lean NdFeB/alpha-Fe nanocomposite magnets produced by melt-spinning. Here, in the heat-treated ribbon at 750 degrees C for 30 min, we obtained a combination of coercivity of 450 Oe, a high-saturation magnetization of 232 emu/g in the heat-treated ribbon at 650 degrees C for 30 min, which surpasses most traditional nanocrystalline magnets based on Fe-Co and pricey. The results we present here are expected to serve as a guideline for designing new magnets for industrial applications.
The Effects of Transportation Modes on Campus Use: A Case Study of a Suburban Campus
(Elsevier Science Bv, 2019) Gocer, Ozgur; Gocer, Kenan
Introduction of a Spatio-Temporal Mapping Based POE Method for Outdoor Spaces: Suburban University Campus as a Case Study
(Pergamon-Elsevier Science Ltd, 2018) Gocer, Ozgur; Gocer, Kenan; Basol, Altug M.; Kirac, M. Furkan; Ozbil, Ayse; Bakovic, Mujesira; Ozcan, Baris
Outdoor spaces are important to sustainable cities because they establish a common identity for social life by improving quality of urban living. The relation between outdoor spaces and building groups, competency, use period, and interaction of micro-climatic factors are needed to be investigated from a holistic approach. Unfortunately, the limited and narrow scoped POE studies on outdoor spaces make an overall assessment without causality relation. Other existing studies in outdoor spaces are mostly grouped under the headings such as; user satisfaction, space syntax and behavioral mapping, and biometeorological assessments. The intention of this paper is to introduce a new post-occupancy evaluation (POE) method integrates these studies focusing on various problems in outdoor spaces using spatio-temporal mapping. The comprehensive methodology applied in this research attempted to overcome some of the shortcomings of related studies by conducting a longitudinal study (during a year, as opposed to a few days) and also by objectively analyzing the associations of user behavior and physical attributes as well as the configurational properties of the campus layout. With this method, outdoor spaces can be evaluated in the context of the interaction between the physical environment and its users' behavior and activities, level of satisfaction and perceptions of comfort. The method has been applied on a suburban university campus in Istanbul, Turkey. The main courtyard of the campus has been subjected for map creation and result discussions.
The Marketization of Higher Education in Turkey (2002-2011)
(Palgrave, 2012) Onal, Nevzat Evrim
Pedestrian Tracking in Outdoor Spaces of a Suburban University Campus for the Investigation of Occupancy Patterns
(Elsevier, 2019) Gocer, Ozgur; Gocer, Kenan; Ozcan, Baris; Bakovic, Mujesira; Kirac, M. Furkan
The design of a livable and comfortable environment has been one of the main aims of sustainable university campus design. The creation of outdoor spaces for accommodating amenities has a positive effect on users with regard to various physiological and psychological aspects. Knowing how daily activity patterns and pedestrian movements are distributed across space is important for assessing whether or not human use and design plans are in fact successful. The aim of this study is to determine occupancy patterns and pedestrian routes in outdoor spaces during different seasons at a sustainable university campus by using spatial statistical analyses that involve ANN, MC and SDE. To perform these analyses, the researchers attempted to use a pedestrian tracking method from camera surveillance to aggregate the required data by conducing a longitudinal study. The data that were aggregated by pedestrian tracking was visualized with the use of a spatio-temporal mapping method in GIS. Logistic GWR was performed to seek the relationship between occupancy pattern (clustered distribution) and design layout of open spaces, comprising the variables of proximity to the attraction centers/entrances, and visual integration. The results confirmed that occupants prefer to use the areas that have high visual integration value and are close to attraction centers.
A Post-Occupancy Evaluation Model Based on Spatio-Temporal Mapping Method for University Outdoor Spaces
(Yildiz Technical University, Fac Architecture, 2020) Gocer, Ozqur; Gocer, Kenan; Basol, Altug Melik; Kirac, Mustafa Furkan; Ozbil Torun, Ayse; Bakovic, Mujesira; Ozcan, Baris
Not only do university campuses consist of a variety of social and educational buildings, they also create an integrated system with their outdoor spaces and furniture, recreation and landscape areas. Outdoors have the potential to create social interaction, rest and relaxation, recreation, exchange of ideas and a strong sense of ownership and belonging. Creating a common identity for social life by enabling people to communicate and socialize with each other is the most important function of outdoor spaces. However, although the rationality of external spaces is designed, it is possible to use other than what is expected in practice. The relationship between the external spaces and the building groups, the adequacy, the duration of use, the accessibility and the interaction of the physical environment should be examined with a holistic approach to understand the difference between expectations and reality. In order to identify user needs in outdoor spaces as a way to assess if human use and design intentions are in fact successful, post occupancy evaluation (POE) is recommended as the most significant advanced method. Unfortunately, although studies on the evaluation of indoor spaces have been increasing day by day, there is no comprehensive study of POE that can be applied to the outdoor spaces, especially in university campuses. In this study, a POE method which discusses the variables that affect the use of outdoor space and the interaction between these variables is introduced. The proposed method was applied in a suburban university campus and the results were evaluated in terms of outdoor use.
Understanding the Role of Urban Form in Explaining Transportation and Recreational Walking Among Children in a Logistic Gwr Model: A Spatial Analysis in Istanbul, Turkey
(Elsevier Sci Ltd, 2020) Torun, Ayse Ozbil; Gocer, Kenan; Yesiltepe, Demet; Argin, Gorsev
This study aims to examine associations between urban form factors generally, and street network configuration in particular, and walking for different purposes among children in Istanbul, Turkey. Parents of randomly selected students (ages 12-16) at 20 middle schools (N = 917) completed questionnaires about their socio-economic characteristics and the frequency of their children's walking for recreational and for transportation purposes in their neighbourhood during a typical day. The environment around 400 m of participants' homes was evaluated through GIS-based parcel-level land-use data and segment-based street connectivity measures calculated using space syntax techniques. Logistic geographically weighted regression models were estimated to measure the desired associations while adjusting for socio-economic characteristics. Results demonstrate a marginal association between urban form measures and walking behaviour but only in certain peripheral parts of the city. More importantly, increased directional accessibility, which identifies the extent to which more street length is accessible within few direction changes, is associated with higher odds of recreational walking in particular areas where a strong differentiation between scales of street connectivity structure is evident such as a supergrid of primary roads with inserted organic local streets. In addition, children residing in neighbourhoods with reduced residential density and increased commercial and recreational activities are more likely to walk for transportation purposes. The findings of this study demonstrate that the one-size-fits-all approach may not effectively encourage walking. Urban areas tend to have varying qualities that need to be handled uniquely, and therefore targeted rather than blanket interventions regarding the design of neighbourhoods around schools and homes may be beneficial in supporting walking behaviour of children.
Wear Performance of Ductile Iron After Electrolytic Plasma Hardening
(Redakcia Kovove Materialy, 2019) Ayday, A.; Durman, M.
This study aimed to improve the tribological behavior of electrolytic plasma treated (EPT) ductile iron (DI). For this purpose, ductile iron was electrolytic plasma hardened under different processing parameters (treatment time and thermal cycle). Three different types of specimens were tested: untreated DI, electrolytic plasma hardened DI and remelted DI by two type wear test. It was found that remelted DI performed much better concerning wear resistance than the other samples. The microstructure of the hardened specimens was investigated using optical microscopy. Microhardness profiles and surface hardness were investigated via the Rockwell test. The microstructure and hardness of the EPT hardened layer were dependent on the processing parameters, with the hardness values reaching the range 880-1080 +/- 10 HV0.2.

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