Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Kalkisim, Ozgun(4)
- Karabulut, Besim(4)
- Okcu, Zuhal(4)
- Ozdes, Duygu(4)
- Vural, Alaaddin(3)
- Adanur, Süleyman(2)
- Agar, Guleray(2)
- Altunişik, Ahmet Can(2)
- Bayındır, Funda(2)
- Dağ, Serhat(2)
- Duran, Celal(2)
- Günaydin, Murat(2)
- Kandemir, Raif(2)
- Karabudak, Filiz(2)
- Kaya, Ayberk(2)
- Okcu, Melih(2)
- Sipahi, Ferkan(2)
- Totik, Yaşar(2)
- Yeşildal, Ruhi(2)
- Yildirim, Nalan(2)
- Zamanlou, Hamid(2)
- Çelik, Necati(2)
- Şen, Sadri(2)
- Şüküroğlu, Ebru Emine(2)
- Şüküroğlu, Süleyman(2)
- Abada, A.(1)
- Abbrescia, M.(1)
- AbdusSalam, S.S.(1)
- Abdyukhanov, I.(1)
- Abelleira Fernandez, J.(1)
- Abramov, A.(1)
- Aburaia, M.(1)
- Acar, A.O.(1)
- Adzic, P.R.(1)
- Agrawal, P.(1)
- Aguilar-Saavedra, J.A.(1)
- Aguilera-Verdugo, J.J.(1)
- Aiba, M.(1)
- Aichinger, I.(1)
- Aielli, G.(1)
Yayınlar
- BildiriYalnız künye2020Evaluation of home health care vehicle routing methods by intuitionistic fuzzy AHP
Peker, Iskender; Caybasi, Gokhan; Buyukozkan, Gulcin; Gocer, Fethullah; Kahraman, C.; Cevik Onar, S.; Oztaysi, B.; Sari, I.U.; Cebi, S.; Tolga, A.C.
In our country, Home Health Care (HHC) units support people who are fully bed-dependent in order to provide health services at the right time, place and conditions. Vehicle Routing Problem (VRP) is used for cost, speed and distance optimization in delivering products or services to customers. In addition, there will be improvements in HHC and it will also save on transportation, storage and labor costs by determining the most appropriate VRP’s solution methods. In this respect, the aim of this study is to determine the best VRP’s solution method which can increase the efficiency of HHC. The proposed approach is based on Intuitionistic Fuzzy Analytic Hierarchy Process (IF-AHP) method which is a strong technique for dealing with uncertainties. According to results, the most important criteria is “time based factors”. Meta-heuristic is the appropriate solution algorithms for VRP in HHC.
AtıfScopus3OpenAlex4İncele - MakaleYayıncıda açık erişim2019Scopus SJRQ2FCC-hh: The Hadron Collider: Future Circular Collider Conceptual Design Report Volume 3
Abada, A.; Abbrescia, M.; AbdusSalam, S.S.; Abdyukhanov, I.; Abelleira Fernandez, J.; Abramov, A.; Aburaia, M.; Acar, A.O.; Adzic, P.R.; Agrawal, P.
In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100 TeV. Its unprecedented centre of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries.
AtıfScopus704OpenAlex640İncele - MakaleYalnız künye2019Scopus SJRQ2Assessment of Heavy Metal Contents of Mulberry Samples (Fruit, Leaf, Soil) Grown in Gumushane Province; [Beurteilung des Schwermetallgehaltes bei Maulbeeren (Frucht, Blatt, Boden) aus der Region Gumushane]
Kalkisim, Ozgun; Ozdes, Duygu; Baltaci, Cemalettin; Duran, Celal
The present study aims to identify the heavy metal contents of white mulberry (Morus alba L.) and black mulberry (Morus nigra L.) that are grown in the city center of Gumushane province and its neighboring counties. Heavy metal analyzes were performed in the fruits, leaves and soils of the plants. The control samples, on the other hand, were collected from the mulberry trees located 3 km away from the highway where the vehicle traffic and industrial activities are at their lowest. Sample collection was performed twice a year, namely during the ripening period and fully ripening period of the fruits. The analyses of the heavy metals were performed by using inductively coupled plasma-mass spectrophotometry (ICP-MS). The obtained results were compared with the acceptable limits of heavy metal for humans as established by the World Health Organization (WHO), Turkish Food Codex (TFC) and the literature and an opinion was submitted as to whether they present any risk in terms of human health. When the available data is evaluated, the mulberries grown in Gumushane province, were found to have presented a health risk in terms of Pb, Cd, Ni, Cu, Zn, Mn and Co metals.
AtıfScopus10WoS9OpenAlex13İncele - MakaleYalnız künye2019Scopus SJRQ2Production of silicone-based composite doped with waste NdFeB magnet and determination of mechanical properties by transforming experimental results into images
Çelik, İlhan; Akben, Selahaddin Batuhan; Mazlum, Uğur
Waste neodymium–iron–boron (NdFeB)-doped silicon-based magnetic polymer composites are obtained by mixing the double-doped mixtures with a 70–30% ratio. In this study, composite materials were produced by adding NdFeB magnetic particles with sizes between 0–45, 45–63, 63–125, and over 125 (µm), and compression experiments were carried out to determine the mechanical properties of them. Experimental results were transformed into images and then analysed using image processing methods. According to the analysis of images representing the results of compression experiments, the strength values of NdFeB–RTV (vulcanized at room temperature) silicone rubber have increased by increasing the magnetic powder ratio. In addition, it was observed that there is a decrease in the elongation at break values due to weakening of polymer chain bonds. Considering the sensitivity of the successfully produced composite materials to the magnetic field, significant improvements in strength values were obtained. It is hoped that these results will lead to an increase in the recycling rate of waste magnets and will prevent environmental damage.
AtıfScopus2WoS3OpenAlex2İncele - BildiriYalnız künye2019Scopus SJRQ4Teachers’ Resistance to Mobile Learning in Turkey and Spain: What Similarities? What Differences?
Aliagas, Cristina; Mutlu, Tugba; Roy, L.; Boustany, J.; Grassian, E.; Mizrachi, D.; Špiranec, S.; Huotari, M.L.; Kurbanoglu, S.; Ünal, Y.
The aim of this paper is to present the data on secondary school teachers’ resistant attitudes towards integrating digital technologies and literacies into their classrooms. The data was gathered through qualitative interviews in the frame of two distinct one-to-one technology programs that took place in distant socio-cultural and educational contexts: the FATIH Project of Turkey and the Escuela 2.0/EduCAT1x1 of Catalonia/Spain. This comparative analysis shows that teachers mainly resist educational change and the government, although they slightly differ in the underlying assumptions supporting their resistance. Their discourses on technology in schools have settled into “discourses of uncertainty” where negative attitudes are compensated with slightly positive comments about digital artefacts and literacies as tools for learning. Findings also indicate that teachers, regardless of the educational context they work in, have assumed the “discourse of inevitability” that dominates viewpoints concerning technology and digital literacy in education.
AtıfScopus1WoS1OpenAlex1İncele - MakaleYalnız künye2019Scopus SJRQ1The in situ natural radionuclide (238U,232Th and40K) concentrations in Gümüşhane granitoids: implications for radiological hazard levels of Gümüşhane city, northeast Turkey
Maden, Nafiz; Akaryalı, Enver; Çelik, Necati
We have carried out 48 in situ measurements on radioactivities of 238U, 232Th and 40K isotopes at the Gümüşhane granitoid plutons employing gamma-ray spectrometer with a NaI(Tl) scintillation detector. The radionuclide activity concentrations of 40K, 238U and 232Th ranged from 62.6 to 1680.8 Bq kg−1, 2.5 to 119.9 Bq kg−1 and 3.3 to 92.4 Bq kg−1, respectively. The mean concentration of natural radionuclides (40K, 238U and 232Th) was found to be 638.5 ± 421.6 Bq kg−1, 40.8 ± 27.4 Bq kg−1 and 33.5 ± 25.5 Bq kg−1, respectively. The mean values of the radium equivalent and the external hazard index were 137.9 ± 80.6 Bq kg−1 and 0.37 ± 0.22, respectively. The value of annual effective dose equivalent value (81.8 μSv year−1) is lower on average than in the world average of 460 μSv year−1. The external hazard index acquired in this study did not exceed the international safety standard levels, which means that Gümüşhane pluton does not produce any radiation hazards to the dwellers.
AtıfScopus9WoS8OpenAlex8İncele - Kitap BölümüYalnız künye2019COPRAS method with neutrosophic sets
Şahin, Rıdvan
Interval neutrosophic number (INN), which is descripted by the degree of truth-membership, indeterminacy-membership and falsity-membership of an element, is a powerful information tool with many application areas. The purpose of this study is to develop an extended form of COPRAS (Complex Proportional Assessment) method used for solving the decision making problems in which all the data presented by decision makers is in the form of interval neutrosophic matrix presented by INNs, and the information about criterion weights is partially known or completely unknown. In order to accomplish this goal, a new score function and an accuracy function that consider the decision maker’s risk attitude are defined under a parameter called the risk index to determine the ordering of INNs. Then, based on Maclaurin symmetric mean (MSM) operator that can capture the interrelationships among multi-input arguments, some aggregation operators are defined, such as interval neutrosophic Maclaurin symmetric mean (INMSM) operator and interval neutrosophic weighted Maclaurin symmetric mean (INWMSM) operator. Moreover, some optimization models are established to determine the subjective and objective weights of decision criteria. A numerical problem is solved to demonstrate the effective and feasible structure of the developed method. Then, a sensitive analysis is conducted according to the decision maker’s risk attitude, and the advantages of the developed method are listed. Finally, a comparison analysis is provided to present the relationships among the developed method and existing methods, and some conclusions are given at the end of the study.
AtıfScopus6OpenAlex6İncele - MakaleYalnız künye2018Scopus SJRQ1Multipath interference cancelation in GPS time series under changing physical conditions by means of adaptive filtering
Üstün, Aydın; Yalvaç, Sefa
Multipath, a highly autocorrelated signal is observable phenomena during time periods longer than the sidereal period of Global Positioning System (GPS) satellites in their constellations. Multipath pattern and sidereal repeat time interaction are examined in terms of time series correlations of topocentric coordinates using GPS code and phase observations collected at high and low frequencies. The horizontal and vertical components at 5 and 30 s sampling rates are analyzed to detect and remove multipath classified by their MP1 levels and baseline lengths. For the selected 11 stations that have 24-hour data from CORS stations in the USA and Turkey, the repeat times of the GPS constellation were identified as a function of maximum cross-correlation of adjacent time series. The multipath interference signal from two-day time series data is removed by an adaptive filter to improve time series of coordinate estimates. After the filtering process, an effective epoch based position tracking has been accomplished, especially in the height component. The position errors disappeared to maximum possible extent in the pseudo-range measurements. Up to 70% improvement for the phase derived coordinates in reflective environment has been achieved over the baselines ranging from 1 km to 175 km. For the phase observables, the filter success directly related to the multipath level which is specific to the station.
AtıfScopus3WoS2OpenAlex4İncele - MakaleAçık Erişim2018Scopus SJRQ2Sensitivity-Based Model Updating of Building Frames using Modal Test Data
Altunişik, Ahmet Can; Karahasan, Olguhan Şevket; Genç, Ali Fuat; Okur, Fatih Yesevi; Günaydin, Murat; Adanur, Süleyman
Model updating is of significant importance in the actual analyses of real structures. The differences between experimental and numerical dynamic characteristics can be minimized by means of this procedure. This procedure can be carried out using two approaches, namely, the manual model updating and the global or local automated model updating. The local model updating is a convenient tool for all kind of structures capable of minimizing the differences mentioned previously nearly to zero and also of identifying the damage locations and monitoring structural integrity. In this way, current realistic behavior of structures can be represented by updated finite element models. This paper describes a Reinforced Concrete (RC) frame model, its ambient vibration testing, finite element modeling and sensitivity-based automated model updating. The RC frame is of ½ geometric scale with two floors and two bays in the longitudinal direction. It was built and then subjected to ambient vibration tests to determine experimentally their dynamic characteristics. Additionally, the finite element computer program ANSYS was used to determine its initial numerical dynamic characteristics. The experimental and numerical results were compared resulting in maximum differences of 38.38% between them. To minimize these differences, the finite element model was updated using the global and local automated approach using a sensitivity-based analyses with some uncertain parameters. The differences were finally reduced to 4.4% and 0.21% by the global and the local automated model updatings, respectively. It is concluded that sensitivity-based automated updating is a very effective procedure to obtain the updated finite element model which can reflect the current behavior of a structure.
AtıfScopus14WoS13OpenAlex13İncele - MakaleYalnız künye2018Bearing capacity and slope stability assessment of rock masses at the Subasi viaduct site, NE, Turkey
Kaya, Ayberk; Bulut, Fikri; Dağ, Serhat
This study investigates the bearing capacity of rock masses and stability of slopes at the Subasi viaduct site which is a part of the improvement project of the Artvin–Hopa government highway between KM 6 + 500 and 13 + 787 in NE Turkey. The geotechnical studies were performed in three stages. Firstly, the bearing capacity of moderately weathered andesitic tuff was evaluated using the empirical equations. Secondly, the major principal stress and vertical displacement due to the viaduct and traffic loadings at the level of foundations were determined by the finite element method (FEM). The vertical displacement value and comparison of bearing capacity and major principal stress show that any problem is not expected at the viaduct site in terms of the bearing capacity. Finally, the stability of slopes at the viaduct site was investigated using kinematic, limit equilibrium, and finite element method-based shear strength reduction analyses methods. It was concluded that no discontinuity controlled failures at the slopes are expected. However, a circular failure is possible to occur at the face slope excavated in highly weathered andesitic tuff. After support application, the long-term stabilization of face slope has been achieved. Consequently, it is suggested that the empirical, analytical, and numerical methods should be combined for a more reliable construction design.
AtıfScopus6WoS5OpenAlex10İncele - MakaleYalnız künye2018Scopus SJRQ2Natural convection in a parallel-plate vertical channel with discrete heating by two flush-mounted heaters: effect of the clearance between the heaters
Sarper, Bugra; Saglam, Mehmet; Aydin, Orhan; Avci, Mete
In this study, natural convection in a vertical channel is studied experimentally and numerically. One of the channel walls is heated discretely by two flush-mounted heaters while the other is insulated. The effects of the clearance between the heaters on heat transfer and hot spot temperature while total length of the heaters keeps constant are investigated. Four different settlements of two discrete heaters are comparatively examined. Air is used as the working fluid. The range of the modified Grashof number covers the values between 9.6 × 105 and 1.53 × 10.7 Surface to surface radiation is taken into account. Flow visualizations and temperature measurements are performed in the experimental study. Numerical computations are performed using the commercial CFD code ANSYS FLUENT. The results are represented as the variations of surface temperature, hot spot temperature and Nusselt number with the modified Grashof number and the clearance between the heaters as well as velocity and temperature variations of the fluid.
AtıfScopus22WoS19OpenAlex22İncele - MakaleYalnız künye2018Scopus SJRQ2Solving power transmission line routing problem using improved genetic and artificial bee colony algorithms
Eroğlu, Hasan; Aydin, Musa
In engineering studies, finding the best route from a start point to an end point on pixel-based weighted maps is a big problem for researchers. For this problem many methods and algorithms have been developed until now. The “cost distance” (CD) and “cost path” (CP) tools that are used by a modified Dijkstra’s algorithm and used by Environmental Systems Research Institute’s (ESRI) ArcGIS Desktop 10 software are very fast and most preferred solutions for route optimization problems. Despite the advantages of these tools, they have the disadvantage of making a lot of curves with big angles. Especially in some engineering studies like power transmission lines’ routing, the angle of the curves of the lines should not have big values. For overcoming this problem both genetic algorithm (GA) and artificial bee colony (ABC) algorithm that have been improved and adapted for the problem were used as powerful optimizers to find the best routes with fewer curves in those kinds of optimum route problems. New functions like smart direction sensing and improved random functions were developed for application of GA and ABC algorithms in power transmission lines routing studies. This study showed that the ABC algorithm’s performance is better than GA. The accuracy of the algorithms was proven by comparing the results with the CD–CP tools’ results. The experimental results showed that the improved algorithms gave better performance than Dijkstra’s algorithm.
AtıfScopus15WoS12OpenAlex17İncele - MakaleYalnız künye2018Scopus SJRQ2Differential scanning calorimetry (DSC) and Ni+2 release analysis of NiTi-shape-memory dental alloys coated by micro-arc oxidation (MAO) method
Yeşildal, Ruhi; Karabudak, Filiz; Şüküroğlu, Ebru Emine; Şüküroğlu, Süleyman; Zamanlou, Hamid; Bayındır, Funda; Şen, Sadri; Totik, Yaşar
This study aims to prevent the release of Ni+2 and increase the biocompatibility of NiTi-shape-memory dental alloys with the micro-arc oxidation (MAO) coating by preserving the shape-memory feature in the oral environment. The TiO2-ceramic coating and Ag-doped TiO2 coating have been grown on shape-memory, co-atoms’ dental NiTi alloys with the MAO method. Biocompatibility properties of the coating were determined by in-vitro tests. In-vitro tests have been made as retention tests in a simulated body fluid (SBF). Whether the grown surface coating impacts the shape-memory properties of the base material or not has been determined by differential scanning calorimetry (DSC) analysis. It was observed as a result of retention tests that bone-like apatite form occurred on the surface of TiO2-coated NiTi and Ag-doped TiO2-coated NiTi coating. It was determined as a result of retention tests in SBF that the Ni+2 release rate from the base material was below the limit of detection in coated samples. As a result of DSC analysis, it was not observed any significant changes in transformation temperature with the MAO coating. It was concluded that the thin-film coatings formed by MAO technique prevent the release of Ni in the oral environment and increase the biocompatibility by preserving shape memory properties of NiTi dental alloys.
AtıfScopus10WoS9OpenAlex10İncele - MakaleYalnız künye2018Scopus SJRQ2Lipophilization of chitin as novel polymeric stabilizer for improved oil-in-water emulsions
İlyasoğlu, Huri; Anankanbil, Sampson; Nadzieja, Marcin; Guo, Zheng
To develop novel polymeric emulsifiers/stabilizers for improved functionalities, an array of chitin fatty acid esters (chitin octanoate, laurate, palmitate, and stearate) were synthesized using a trifluoroacetic anhydride (TFAA)/methanesulfonic acid (MSA) catalytic system. The synthesized products were characterized by Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC); successful lipophilization of chitin was confirmed by analysis results of FTIR, NMR, and DSC, with the degree of substitution (DS) of the products that ranged from 0.89 to 1.05. Ten percent fish oil-in-water emulsions were prepared using the synthesized chitin fatty acid esters, and characteristic properties (droplet size, zeta potential, and creaming stability) were determined. It turned out that chitin octanoate and chitin laurate were capable to solely enable homogeneous nanoemulsion (200–240 nm, polydispersity index 0.22–0.26), with excellent stability (no creaming after 14-day storage), which may find great potential applications in food, biomedical, and cosmetics sectors.
AtıfScopus4WoS4OpenAlex6İncele - MakaleYalnız künye2018Relationship between the geological environment and element accumulation capacity of Helichrysum arenarium
Vural, Alaaddin
This study was carried out to determine the effect of geological environment on the biogeochemical properties of Helichrysum arenarium. Plant samples from Upper Cretaceous andesite, basalt, and their pyroclasts; Eocene andesite, basalt, and their pyroclasts; and Upper Eocene granitic rocks were collected. Roots, stems, and flowers of the plant were analyzed to determine their major and trace elements, such as Ca, Mg, Al, Na, K, Fe, Mn, U, Sr, P, La, Cr, Ba, Ti, B, W, Hg, Cs, Hf, Rb, Zr, and Ce. This study is one of the few studies in which the element content of H. arenarium is studied in detail and the element accumulation capacities are examined according to the types of rocks the plants grow. Result showed that the plants exhibited different element accumulation capacities according to the lithological environments where they grew. The element concentrations in the root, stem, and flower of the plant were predominantly high in Eocene andesite, basalt, and pyroclasts. High values were also observed in plants grown on the Upper Eocene granitic rock. Some elements were also high in plants grown in the Upper Cretaceous andesite, basalt, and pyroclasts. Therefore, the high element contents of plant are related to the element contents of the rocks where the plants grew. Furthermore, the alteration and tectonic influences on the plants are also influential.
AtıfScopus16WoS13OpenAlex18İncele - MakaleYalnız künye2018Scopus SJRQ2Evaluation of Pomological and Morphological Characteristics and Chemical Compositions of Local Pear Varieties (Pyrus communis L.) Grown in Gumushane, Turkey; [Pomologische und morphologische Eigenschaften sowie Inhaltsstoffe lokaler Birnensorten (Pyrus communis L.) in Gumushane (Türkei)]
Kalkisim, Ozgun; Okcu, Zuhal; Karabulut, Besim; Ozdes, Duygu; Duran, Celal
The aim of the present research was to investigate the fruit quality of twenty different local pear varieties (Pyrus communis L.), namely Ahlat, Ankara, Arpa, Bıldırcın, Çermai, Cinci, Gelin Boğan, Hacı Hamza, Hahır, Kabak, Kızıl, Kokulu, Mehrani, Menendi, Sulu, Şalgam, Tokat Sultanı, Turşu, Yaz, and Yaz Meyriği, grown in Gumushane province in terms of pomological and morphological characteristics and chemical compositions. The fruit mass, fruit width and length, fruit stem thickness and length, fruit kernel width and length, hardness of pulp, number of seeds, leaf width and length, leaf stem length and thickness, and water soluble dry matter (WSDM) of the pear fruits have been determined as pomological and morphological characteristics. On the other hand, the chemical compositions of the pear varieties have been evaluated in terms of protein, ash, sucrose, fructose, glucose, total sugar, titratable acidity, moisture, and mineral element levels. Both pomological and morphological results demonstrated that the local pear varieties are important in terms of rehabilitation studies and detailed selection studies on these local varieties should be performed. The chemical analyses result of the pear varieties revealed that there is no component that may be harmful to human health when consumed, and also these varieties contains the necessary amount of mineral elements.
AtıfScopus10WoS10OpenAlex20İncele - MakaleYalnız künye2017Scopus SJRQ1Zircon Lu-Hf isotope systematics and U–Pb geochronology, whole-rock Sr-Nd isotopes and geochemistry of the early Jurassic Gokcedere pluton, Sakarya Zone-NE Turkey: a magmatic response to roll-back of the Paleo-Tethyan oceanic lithosphere
Karsli, Orhan; Dokuz, Abdurrahman; Kandemir, Raif
The early Mesozoic was a critical era for the geodynamic evolution of the Sakarya Zone as transition from accretion to collision events in the region. However, its complex evolutionary history is still debated. To address this issue, we present new in situ zircon U–Pb ages and Lu-Hf isotope data, whole-rock Sr-Nd isotopes, and mineral chemistry and geochemistry data of plutonic rocks to better understand the magmatic processes. The Gokcedere pluton is mainly composed of gabbro and gabbroic diorite. LA-ICP-MS zircon U–Pb dating reveals that the pluton was emplaced in the early Jurassic (177 Ma). These gabbros and gabbroic diorites are characterized by relatively low SiO2 content of 47.09 to 57.15 wt% and high Mg# values varying from 46 to 75. The samples belong to the calc-alkaline series and exhibit a metaluminous I-type character. Moreover, they are slightly enriched in large ion lithophile elements (Rb, Ba, Th and K) and light rare earth elements and depleted in high field strength elements (Nb and Ti). Gabbroic rocks of the pluton have a depleted Sr-Nd isotopic composition, including low initial 87Sr/86Sr ranging from 0.705124 to 0.705599, relatively high εNd (t) values varying from 0.1 to 3.5 and single-stage Nd model ages (TDM1 = 0.65–0.95 Ga). In situ zircon analyses show that the rocks have variable and positive εHf (t) values (4.6 to 13.5) and single-stage Hf model ages (TDM1 = 0.30 to 0.65 Ga). Both the geochemical signature and Sr-Nd-Hf isotopic composition of the gabbroic rocks reveal that the magma of the studied rocks was formed by the partial melting of a depleted mantle wedge metasomatized by slab-derived fluids. The influence of slab fluids is mirrored by their trace-element characteristics. Trace-element modeling suggests that the primary magma was generated by a low and variable degree of partial melting (~5–15%) of a depleted and young lithospheric mantle wedge consisting of phlogopite- and spinel-bearing lherzolite. Heat to melt the mantle material was supplied by the ascendance of a hot asthenosphere triggered by the roll-back of the Paleo-Tethyan oceanic lithosphere. The rising melts were accompanied by fractional crystallization and encountered no or minor crustal contamination en route to the surface. Taking into account these geochemical data and integrating them with regional geological evidence, we propose a slab roll-back model; this model suggests that the Gokcedere gabbroic pluton originated in a back-arc extensional environment associated with the southward subduction of the Paleo-Tethyan oceanic lithosphere during the early Jurassic period. Such an extensional event led to the opening of the northern branch of the Neotethys as a back-arc basin. Consequently, we conclude that the gabbroic pluton was related to intensive extensional tectonic events, which peaked during the early Jurassic in response to the roll-back of Paleo-Tethyan oceanic slab in the final stage of oceanic closure.
AtıfScopus68WoS64OpenAlex68İncele - MakaleAçık Erişim2017Comparison of stochastic and random models for bacterial resistance
Merdan, Mehmet; Bekiryazici, Zafer; Kesemen, Tulay; Khaniyev, Tahir
In this study, a mathematical model of bacterial resistance considering the immune system response and antibiotic therapy is examined under random conditions. A random model consisting of random differential equations is obtained by using the existing deterministic model. Similarly, stochastic effect terms are added to the deterministic model to form a stochastic model consisting of stochastic differential equations. The results from the random and stochastic models are also compared with the results of the deterministic model to investigate the behavior of the model components under random conditions.
AtıfScopus25WoS25OpenAlex25İncele - MakaleYalnız künye2017Scopus SJRQ2Improving by postoxidation of corrosion resistance of plasma nitrocarburized AISI 316 stainless steels
Yenilmez, A.; Karakan, M.; Çelik, I.
Austenitic stainless steels are widely used in several industries such as chemistry, food, health and space due to their perfect corrosion resistance. However, in addition to corrosion resistance, the mechanic and tribological features such as wear resistance and friction are required to be good in the production and engineering of this type of machines, equipment and mechanic parts. In this study, ferritic (FNC) and austenitic (ANC) nitrocarburizing were applied on AISI 316 stainless steel specimens with perfect corrosion resistance in the plasma environment at the definite time (4 h) and constant gas mixture atmosphere. In order to recover corrosion resistance which was deteriorated after nitrocarburizing again, plasma postoxidation process (45 min) was applied. After the duplex treatment, the specimens’ structural analyses with XRD and SEM methods, corrosion analysis with polarization method and surface hardness with microhardness method were examined. At the end of the studies, AISI 316 surface hardness of stainless steel increased with nitrocarburizing process, but the corrosion resistance was deteriorated with FNC (570 °C) and ANC (670 °C) nitrocarburizing. With the following of the postoxidation treatment, it was detected that the corrosion resistance became better and it approached its value before the process.
AtıfScopus9WoS5OpenAlex10İncele - MakaleYalnız künye2017Scopus SJRQ1Evaluation of potentially toxic element contents and Pb isotopic compositions in Ankara Stream sediments within an urban catchment in central Turkey
Eker, Çiğdem Saydam; Sipahi, Ferkan; Özkan, Özay; Gümüş, Mustafa Kemal
This study aimed to interpret the spatial distribution, enrichment factor (EF), and geo-accumulation of potentially toxic elements in the bed sediments (ASBS) and Pleistocene-aged overbank sediments (ASOS) of the Ankara Stream in Turkey. The potential toxic pollution of the investigated potentially toxic elements was defined by evaluating the EF, geo-accumulation index (Igeo), and Pb anthropogenic contribution. The distributions of As, Ni, and Co in the analyzed sediments were uniform in the ASBS and ASOS along the length of the stream. The EF and Igeo values indicated that ASBS and ASOS were significantly polluted by As and Ni and moderately polluted by Co, Zn, and Cu. ASBS was locally strongly polluted by Pb and Cd. Pb anthropogenic contribution was estimated at an average of > 100% in the ASBS and ASOS. The potentially toxic element levels and distribution patterns revealed that industrial activities, gasoline combustion, vehicular emission, phosphate fertilizers and natural sources were probable causes of metal pollution in Ankara Stream sediments. These potentially toxic elements were transported by atmospheric conditions and stream water. The potentially toxic elements in Ankara Stream increased with each passing day and were important in evaluating the potential toxicity risks to living organisms. Thus, suitable measures should be taken to ensure appropriate treatment of wastewater before toxic residues are disposed into the nearby stream. Chimney filter, treatment plants, and appropriate technology should be used in the organized industrial zone to prevent atmospheric pollution.
AtıfScopus12WoS10OpenAlex12İncele