Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Uzun, Sevda(67)
- Merdan, Mehmet(59)
- Duran, Celal(49)
- Ozdes, Duygu(46)
- Kaygusuz, Abdullah(45)
- Demir, Selim(37)
- Turan, Ibrahim(37)
- Karsli, Orhan(36)
- Öztürk, Serkan(35)
- Dokuz, Abdurrahman(34)
- Araz, Onur(32)
- Kandemir, Raif(31)
- Kulakaç, Nurşen(29)
- Sipahi, Ferkan(29)
- Arslan, Mehmet(27)
- Baltaci, Cemalettin(27)
- Baltacı, Cemalettin(27)
- Kurt, Kemal(27)
- Topal, Fevzi(27)
- Gücer, Mehmet Ali(25)
- Peker, Iskender(25)
- Aydin, Faruk(24)
- Bayrakdaroglu, Serdar(24)
- Maden, Nafiz(24)
- Ozturk, Samet(24)
- Vural, Alaaddin(24)
- Yolcu, Halil(24)
- Yücel, Cem(24)
- Aliyazicioglu, Yuksel(23)
- Kankal, Murat(23)
- Reis, Hatice Catal(23)
- Ürkek, Bayram(23)
- Günen, Mehmet Akif(22)
- Kurnaz, Muammer(22)
- Topal, Meryem(22)
- Karimullah, Suud Sarim(21)
- Uysal, Ibrahim(21)
- Ashyralyyev, Charyyar(20)
- Aydin, Aydanur(20)
- Bayraktar, Alemdar(20)
Yayınlar
- MakaleYalnız künye2018Scopus SJRQ3Automated Model Updating Effect on the Linear and Nonlinear Dynamic Responses of Historical Masonry Structures
Altunişik, A.C.; Okur, F.Y.; Genç, A.F.; Günaydin, M.; Karahasan, O.
Finite element models supply the simulation of the problems to obtain the structural behaviors under different loading conditions. The updating processes based on changing the uncertain parameters such as material properties, boundary conditions, meshing size etc. are made to create actual finite element models in order to represent the real conditions of the problems. This procedure can be made using two methods, namely manual model updating and global/local automatic model updating. The global/local automatic model updating procedures are very popular owing to the applicability to all kind of engineering structures, minimizing the differences nearly to zero, availability of damage localization and structural health monitoring. In this paper a historical masonry armory building selected as an application and its finite element analyses, experimental measurements and automated model updating processes are carried out. The finite element model of the structures was developed with ANSYS software and first three natural frequencies are attained. The experimental dynamic characteristics such as natural frequencies, damping ratios and mode shapes are obtained using ambient vibration method. The differences between experimental and numerical frequencies are minimized up to the range of 0–1%, by using local updating procedure. The linear and nonlinear seismic analyses of the building are conducted on initial and updated models. At the end of the analyses, maximum displacements, principal stresses and strains are given with detail. In addition, crack distributions diagrams are attained to validate the stresses accumulation points. It can be seen that there is an increasing trend in the displacement, stress and strain values after finite element model updating both linear and nonlinear analysis. In addition, linear and nonlinear analysis results are compared with each other to evaluate the nonlinear analysis effect. It is concluded that the displacement and strain values are increased after nonlinear analysis. But, there is not any agreement in stress values.
AtıfScopus17WoS15OpenAlex15
İncele - MakaleYalnız künye2018Scopus SJRQ2An enhanced scanning-based MPPT approach for DMPPT systems
Başoğlu, Mustafa Engin
In this paper, an improved maximum power point tracking (MPPT) approach being low parameter dependency, simple structure and limited search interval has been presented for distributed MPPT photovoltaic (PV) systems. Basically, this approach is based on scanning of power–voltage (P-V) characteristic curve of PV modules in a limited duty ratio interval which makes tracking operation simple, fast and efficiently available in both uniform irradiance and partial shading conditions (PSCs). By limiting the scanning interval of maximum and minimum values of duty ratio via some analyses related to P-V characteristic for PSCs, global MPPT (GMPPT) is achieved in an efficient way. So as to validate performance of the proposed approach, a single-ended primary inductance converter has been used in both simulation and experimental studies. PV simulator has been used as a PV source to obtain different module characteristics with different number of bypass diodes and PV power levels. Both simulation and experimental results clarify that improved MPPT approach realises GMPPT effectively. Due to the high performance results, this approach can be an alternative technique in module-integrated converters, smart modules and PV power optimisers in which single module is used.
AtıfScopus27WoS23İncele - MakaleAçık Erişim2018Scopus SJRQ1Indoor and outdoor radon measurements at lung cancer patients’ homes in the dwellings of Rize Province in Turkey
Özen, Songül Akbulut; Celik, Necati; Dursun, Emrehan; Taskın, Halim
In this study, indoor and outdoor radon (222Rn) surveys were carried out in the summer and winter seasons in homes of one hundred lung cancer patients in the year 2013–2014. The aim was to investigate the relationship between radon and cancer patients. Lung cancer patients completed a questionnaire concerning their living environment, various physical parameters and living habits. Pearson correlation and t tests revealed no meaningful results between radon concentrations, on one hand, and environmental and personal living habits, on the other hand. Consequently, the BEIR VI model was adapted and 222Rn exposure was estimated to be responsible for about 12% of the lung cancer incidences in the winter season and around 5% in the summer season in the Rize Province. However, due to the limited number of data and numerous parameters that could lead to lung cancer, the estimations done with the model should be taken very lightly. The annual effective doses due to inhalation of indoor and outdoor 222Rn were estimated to be, respectively, 1.43 and 0.94 mSv y−1. The indoor and outdoor annual effective doses were, respectively, close and below the world annual effective dose (1.3 mSv y−1). At the district level, the indoor annual effective dose equivalent in the İyidere district was 4.52 mSv y−1, which was 3.5 times greater than the world average. The number of patients in the majority of the houses in this district was more than one.
AtıfScopus31WoS27OpenAlex33
İncele - MakaleYalnız künye2018Scopus SJRQ3Solving 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 SJRQ4Optimization of drying parameters for chestnut fruits using central composite design
Koca, I.; Yilmaz, V.A.; Odabas, I.H.; Tekguler, B.
The chestnut drying process was optimized by Response Surface Methodology (RSM). A central composite design with two numerical factors was selected for modelling the drying process. The numerical factors were air temperature from 40 to 60°C and air velocity from 0.75 to 1.75 m s-1. The investigated responses were color values, including lightness (L*), redness (a*), yellowness (b*), total color changes (ΔE) and browning index (BI). The study revealed that the drying temperature was significantly effective on lightness, redness, total color changes and browning index. However, none of the independent variables were significant on yellowness. The L*, a*, ΔE and BI of chestnuts during drying process were adequately described by RSM models. According to desirability function, the optimum drying conditions of chestnuts were 40°C and 0.75 m s-1 air. At optimum conditions, predicted L*, a*, ΔE and BI values were 76.34, -0.20, 7.45 and 17.00, respectively. Under optimized conditions the experimental values of L* (77.46), a* (-0.36), ΔE (6.31) and BI (16.88) agreed with the predicted values. RSM was not successful to develop a satisfactory model for b* values of chestnuts during drying process.
AtıfScopus2OpenAlex1İncele - MakaleAçık Erişim2018Scopus SJRQ2Purification and selected biochemical properties of peroxidase from cress (Lepidium sativum sub sp. sativum)
Altay, Ahmet; Koktepe, Tubanur; Durmaz, Lokman; Topal, Fevzi; Gülçin, İlhami; Köksal, Ekrem
Cress (Lepidium sativum) is an annual herb from Brassicaceae family, and in some regions. It is known as peppergrass, garden cress, garden pepper-cress, pepperwort, or poor man’s pepper. Cress is an important medicinal plant in some countries including Turkey. This plant has major scientific and therapeutic significance. Peroxidase (POD, E.C.1.11.1.7) is an oxidor-eductase enzyme produced by a number of organisms. In this study, POD enzyme was purified from cress by ammonium sulphate precipitation, gel filtration, and CM-Sephadex ion-exchange chromatographies. K m and V max values were calculated from the Lineweaver-Burk graph for H 2 O 2 and guaiacol substrates and the substrate specificity of POD was investigated. The results showed that substrate specificity of H 2 O 2 is better than substrate specificity of guaiacol for this enzyme. The inhibition effects of three cations (Al 3+ , Cu 2+ , and Cr 3+ ) and one organic compound of cetyl trimethylammonium bromide were performed and their inhibition types were determined. Finally, optimum pH, optimum temperature, optimum ionic strength, and stable pH were determined.
AtıfScopus14WoS15İncele - MakaleYalnız künye2018Scopus SJRQ4Open source library-based 3D face point cloud generation
Bayram, Bulent; Ozkan, Taskin; Reis, Hatice Catal; Bakirman, Tolga; Cetin, Ibrahim; Seker, Dursun Zafer
Three dimensional (3D) face and body modeling is widely used in various fields such as plastic surgery, diagnosis of facial or body anomalies, 3D computer games and 3D simulation software. Since, commercial 3D face and body scanners are usually expensive, an alternative solution with lower cost is highly desirable. The objective of this study is to create 3D facial point cloud using Semi Global Image Matching method with minimum number of images utilizing a cost effective method. A non-metric Canon 600D camera with 18 megapixels resolution (3456 × 5184) and 60 mm macro lens have been used for face imaging that have been taken from a distance of 120 cm. Five faces have been modeled by the developed algorithm and scanned by David SLS-2 structured light system for accuracy assessment. Open source Cloud Compare software has been used for comparing the results of proposed method with the structured light system. The mean accuracy of five faces obtained as 90.5%. It has been observed that illumination conditions, uncontrolled movements of face or body, hair and eyebrow have negative impacts on the obtained results. The sufficiency of Semi global image matching method has been tested to create dense point cloud data from three stereo pairs for 3D facial modelling.
AtıfScopus3WoS2İncele - MakaleYalnız künye2018Scopus SJRQ3Geochemistry of Çoruh River Bed Sediments in NE Turkey: Implications in Weathering-Sedimentary Cycle, Provenance, and Metal Pollution
Eker, Ç.Saydam.; Kiliç, E. Demirkol
This study defines the source area, sub-aerial weathering, and sedimentary cycle level, as well as heavy metal content and origin, of the Çoruh River bed sediments. The studied sediments are geochemically classified as litharenite based on the ratio of the major element contents. Relative to the Upper Continental Crust (UCC), trace elements Rb, Sr, Ba, Th, U, Zr, Hf, Y, Nb, and Pb are generally depleted; Co, Ni, Cu, Sc, and V are generally enriched; and Au is depleted in some places and enriched in other places. The rare earth element (REE) distributions of the samples exhibit a trend similar to that of the upper continental crust (UCC); however, low to moderate depletion occurs in the bed sediments in UCC. The analyzed samples exhibit low Chemical Index of Alteration (CIA) values, Plagioclase Index of Alteration (PIA) values (<50), CIA/WIP (Weathering Index ratios <1), and substantially high Index of Compositional Variability values (ICV) (>1). Thus, the samples are not chemically mature and are mainly derived from non-altered sources and were exposed the simple cycling history. REEs are depleted in the river bed sediments, unlike the world river average silt, world river average clay, and suspended sediment in world rivers. Minor enrichment of Zn, Sn, and Sc contents, low-to-moderate enrichment of Cu content, very severe enrichment of as content, and extremely severe enrichment of Ni content of the analyzed samples are observed. Consequently, stream bed sediments are derived from intermediate sources close to mid-continental crust rather than felsic sources Low-to-moderate degrees of chemical weathering of these sediments indicate increased tectonic activity, increased erosion, and rapid sedimentation in semiarid to arid conditions in the source regions over time. Thus, the sediments are chemically immature. These sediments are exposed to lithogenic and anthropogenic contamination.
AtıfScopus19WoS17OpenAlex21İncele - MakaleAçık Erişim2018Scopus SJRQ1The effect of energy resolution of detection instrument on mass attenuation coefficient
Çelik, N.; Özen, S.A.; Demirtaş, Ö.F.; Çevik, U.
The effect of energy resolution of two detection systems, HPGe and NaI(Tl), was determined by Monte Carlo (MC) calculation on mass attenuation coefficients of magnesium (Mg) and tungsten (W). In order to reveal the energy resolution effect, the detectors' collimator diameters were changed from 2 mm to 20 mm while sending collimated photon beams to the absorber material. It was observed that mass attenuation coefficients were increased with increasing collimator diameters. The performances of HPGe and NaI(Tl) detectors were quantified. The calculated results were compared with experimental results for Mg at energy of gamma rays 662 keV for different collimator diameters using both HPGe and NaI(Tl). It was observed that the MC calculation results were in a good agreement with the experimental data within the relative error from around 4% to 8%.
AtıfScopus8WoS7OpenAlex7İncele - 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 SJRQ1Carrier transport mechanism and bipolar resistive switching behavior of a nano-scale thin film TiO2 memristor
Gul, Fatih
A titanium dioxide (TiO2) based memristor device having an active layer thickness of 10 nm was fabricated using radio frequency (RF) reactive sputtering and its resistive switching characteristics and carrier transport mechanisms were investigated. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to confirm the structural properties of the device. Measurement of the time-dependent current-voltage (I-V-t) was used to characterize resistive switching and memristive behavior. The characteristic pinched hysteresis I-V loops of the memristor were apparent. Bipolar and homogeneous resistive switching characteristics and a forming voltage of 2 V were detected in the device. The retention time exceeded 103 s and the endurance test was reasonably acceptable. In addition, the carrier transport mechanism of the device was revealed. The linear region of the low electric field demonstrated ohmic behavior, whereas the non-linear high electric field region was dominated by a Schottky emission carrier transport mechanism. A Poole-Frenkel emission mechanism acted as a secondary conduction mechanism. It was proposed that the Poole-Frenkel and Schottky emission mechanisms were associated with oxygen vacancies in the TiO2.
AtıfScopus69WoS69OpenAlex77İncele - MakaleAçık Erişim2018Scopus SJRQ2Investigation of Antibacterial Susceptibility of Ag-Doped Oxide Coatings onto AZ91 Magnesium Alloy by Microarc Oxidation Method
Sukuroglu, Ebru Emine
This study is focused on enhancing surface characteristics of AZ91 alloy with the microarc oxidation (MAO) method and bringing in antibacterial susceptibility to it. It is aimed to bring in antibacterial effect of silver (Ag) to AZ91 magnesium base materials covered with the MAO method. The structural and chemical compositions of the coating were analysed by using XRD, SEM, and EDS. In order to analyse antibacterial susceptibilities and bacteria adhesions, bacteria are marked using crystal violet in antibacterial efficacy tests. Susceptibility of coatings to Staphylococcus aureus (S. aureus-ATCC 29213) bacteria having high adhesion is analysed. In the study, it is concluded that the silver-containing coatings have a lot poor bacterial susceptibility than silver-free coatings, and noncoated samples have very strong bacterial susceptibilities. When the antimicrobial activity of the samples coated on silver-containing electrolyte is evaluated (zone diameter ∼40 mm), it is found as sensitive. Antimicrobial activity of samples coated in silver-free electrolyte is found as medium-sensitive (zone diameter ∼15 mm), and uncoated samples are observed to form any zones against bacterial infection.
AtıfScopus18WoS14OpenAlex19İncele - MakaleAçık Erişim2018Scopus SJRQ3Textural, rheological and pasting properties of dough enriched with einkorn, cranberry bean and potato flours, using simplex lattice mixture design
Yuksel, F.; Campanella, O.H.
The aim of this study was to analyse the effects of the addition of einkorn, cranberry bean and potato flours on the pasting characteristics of the mixture as well as the rheological properties of the dough formed. An experimental design using a simplex lattice mixture design was employed. The pasting parameters of the samples increased with the addition of cranberry bean and einkorn flours due to their high protein content. The water absorption capacities of the doughs were significantly affected by the polar nature (e.g. potato flour) and protein content (e.g. cranberry bean) of the flours. The creep-recovery properties of the doughs were analysed using the Burger model. Results showed that doughs enriched with potato flour exhibited weak elastic properties and behaved as a highly viscous material. Textural profile analysis of the doughs showed that their structure became firmer with addition of einkorn, cranberry bean and potato flours. The determination coefficient for the samples was higher than 0.70 in the simplex lattice mixture design.
AtıfScopus7WoS7OpenAlex7İncele - MakaleAçık Erişim2018Scopus SJRQ2Single production of the excited electrons in the future FCC-based lepton-hadron colliders
Caliskan, A.; Kara, S.O.
We study the composite electron production at the FCC-based three electron-proton colliders with the center-of-mass energies of 3.46, 10 and 31.6 TeV. For the signal process of ep → e→ X eγX, the production cross-sections and decay widths of the excited electrons have been calculated. The differences of some kinematical quantities of the final state particles between the signal and background have been analyzed. For this purpose, transverse momentum and pseudorapidity distributions of electron and photon have been obtained and the kinematical cuts for discovery of the excited electrons have been assigned. We have finally determined the mass limits of excited electrons for observation and discovery by applying these cuts. It is shown that the mass limit for discovery obtained from the collider with √s = 31.6 TeV (called PWFA-LC-FCC) is 22.3 TeV for the integrated luminosity Lint = 10fb-1.
AtıfScopus7WoS6İncele - MakaleYalnız künye2018Scopus SJRQ2Earthquake hazard potential in the Eastern Anatolian Region of Turkey: seismotectonic b and Dc-values and precursory quiescence Z-value
Öztürk, S.
The Eastern Anatolian Region of Turkey is one of the most seismically and tectonically active regions due to the frequent occurrence of earthquakes. Thus, the main goal of this study is to analyze the regional and temporal characteristics of seismicity in the Eastern Anatolia in terms of the seismotectonic b-value, fractal dimension Dc-value, precursory seismic quiescence Z-value, and their interrelationships. This study also seeks to obtain a reliable empirical relation between b and Dc-values and to evaluate the temporal changes of these parameters as they relate to the earthquake potential of the region. A more up-to-date relation of Dc = 2:55–0:39*b is found with a very strong negative correlation coefficient (r =–0.95) by using the orthogonal regression method. The b-values less than 1.0 and the Dc-values greater than 2.2 are observed in the Northeast Anatolian Fault Zone, Aşkale, Erzurum, Iğdır and Çaldıran Faults, Doğubeyazıt Fault Zone, around the Genç Fault, the western part of the Bitlis-Zagros Thrust Zone, Pülümür and Karakoçan Faults, and the Sancak- Uzunpınar Fault Zone. In addition, the regions having small b-values and large Z-values are calculated around the Genç, Pülümür and Karakoçan Faults as well as the Sancak-Uzunpınar Fault Zone. Remarkably, the combinations of these seismotectonic parameters could reveal the earthquake hazard potential in the Eastern Anatolian Region of Turkey, thus creating an increased interest in these anomaly regions.
AtıfScopus51WoS36OpenAlex53İncele - MakaleAçık Erişim2018Scopus SJRQ1Combination of discontinuity characteristics and GIS for regional assessment of natural rock slopes in a mountainous area (NE Turkey)
Bostanci, Hasan Tahsin; Alemdag, Selcuk; Gurocak, Zulfu; Gokceoglu, Candan
Geographical Information Systems (GIS) have a very large spectrum of users. As in many engineering applications, GIS are frequently used in geotechnical projects, especially in producing various thematic and zoning maps such as various susceptibility and hazard maps. Instability maps for large areas with similar characteristic can be produced in a practical way by evaluating the results obtained by the data collected from field and laboratory studies. In order to introduce a methodology for producing rock slope instability maps for a large area, discontinuity controlled slope failures in the Köse Granitoid Complex (NE Turkey) were selected. To determine the types of failure such as planar, wedge, and toppling, and possible instable slope orientations kinematic analyses were carried out in the limited areas. The relationships between orientations of natural slopes and discontinuities obtained from kinematic analyses were evaluated with GIS software. Finally, discontinuity controlled instability maps were produced for the study area. Resulting maps show that the most common type of failure is wedge type. Additionally, the distributions of unstable areas along road networks were determined. Various land use types such as agriculture, grassland, settlement, and forest were also classified in order to predict the possible effects of slope instabilities. The methodology introduced in this study indicates highly promising results for the assessment of rock slope instability in large areas.
AtıfScopus22WoS22OpenAlex25İncele - MakaleAçık Erişim2018Scopus SJRQ2Type, quantity, and re-use of residues in the forest products industry in Trabzon, Turkey
Top, Yener; Adanur, Hakan; Oz, Mehmet
It is necessary to know the type and quantity of wastes to select the proper applications and waste management strategies. This study investigates the type, quantity, and utilisation methods of wastes generated by micro-sized enterprises that produce timber and furniture, which are two major sub-sectors of the forest products industry in Trabzon. A total of 885 enterprises of manufacturing timber and furniture in Trabzon were identified by reviewing the records from the professional chambers of commerce. The stratified sampling method was used to compare the sub-sectors, and the sample size was determined as 120. Among these, 70 furniture- and 50 timber-producing enterprises were interviewed. The chi-square test was used to determine whether the applications of timber and furniture enterprises are dependent on each other. In general, there are no differences in waste utilisation applications and education level between the sub-sectors. The percentage of the owners/managers that received any vocational training is 77.5% in two sub-sectors. In general, engineered wood wastes are used as fuel. The majority of the owners/managers in the timber industry believe that their waste has an economic value compared to those in the furniture sector. The total amount of wood waste generated by sectors was 528 tons in a month.
AtıfScopus12WoS14OpenAlex13İncele - MakaleYalnız künye2018Scopus SJRQ2Tracing provenance and chemical weathering changes in Ankara Stream sediments, central Turkey: Geochemical and Sr–Nd–Pb–O isotopic evidence
Saydam Eker, Çiğdem; Sipahi, Ferkan; Gümüş, Mustafa Kemal; Özkan, Özay
This study aims to analyze the changes in sediment provenance through the geochemical and Sr–Nd–Pb–O isotopic composition of the Ankara Stream bed and overbank sediments (ASBS and ASOS) and to examine the weathering and sediment transport processes in response to step climate variability. Major, trace, and rare earth elements, as well as Sr–Nd–Pb–O isotopic composition, exhibit generally similar variations for the investigated samples. These sediments have relatively high εNd(0) values and low 87Sr/86Sr ratios. Similar Pb isotopic ratios also characterize these sediments but have slightly different δ18O isotope values with relatively higher δ18O isotope values in the ASBS and lower δ18O isotope values in the ASOS samples. Chemical indices indicate low–moderate chemical weathering in the step-dominated climate. The low average Zr/Sc and Zr/Nb ratios indicate that such geochemical change was dominated by the composition of the source rocks but not sedimentary recycling with zircon enrichment, reflecting first-cycle deposit. Low radiogenic 87Sr/86Sr ratios and negative εNd(0) values indicate that the investigated sediments are relatively derived from young magmatic provinces, which are intermediate sources. Finally, the findings show that the geochemical compositions of the ASBS and ASOS were dominated by the composition of the source materials that originate from Galatia province and Late Cretaceous- Early Tertiary volcanic rocks in central Anatolia. Reasonable semiarid to arid climatic conditions are observed in the region. Active tectonism, increased erosion, and the investigated sediments are also transported rapidly to the stream channel without chemical alteration, and the sediments are the first-cycle products.
AtıfScopus9WoS7OpenAlex10İncele - 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 künye2018Scopus SJRQ2Constructal Placement of Discrete Heat Sources with Different Lengths in Vertical Ducts under Natural and Mixed Convection
Sarper, Bugra; Saglam, Mehmet; Aydin, Orhan
In this study, convective heat transfer in a discretely heated parallel-plate vertical channel which simulates an IC package is investigated experimentally and numerically. Both natural and mixed convection cases are considered. The primary focus of the study is on determining optimum relative lengths of the heat sources in order to reduce the hot spot temperature and to maximize heat transfer from the sources to air. Various values of the length ratio and the modified Grashof number (for the natural convection case)/the Richardson number (for the mixed convection case) are examined. Conductive and radiative heat transfer is included in the analysis while air is used as the working fluid. Surface temperatures of the heat sources and the channel walls are measured in the experimental study. The numerical studies are performed using a commercial CFD code, ANSYS FLUENT. The variations of surface temperature, hot spot temperature, Nusselt number, and global conductance of the system are obtained for varying values of the working parameters. From the experimental studies, it is showed that the use of identical heat sources reduces the overall cooling performance both in natural and mixed convection. However, relatively decreasing heat sources lengths provides better cooling performance.
AtıfScopus11WoS11OpenAlex12İncele