Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Uzun, Sevda(66)
- Merdan, Mehmet(56)
- Duran, Celal(50)
- Ozdes, Duygu(47)
- Kaygusuz, Abdullah(42)
- Demir, Selim(37)
- Turan, Ibrahim(37)
- Ashyralyyev, Charyyar(34)
- Dokuz, Abdurrahman(33)
- Araz, Onur(31)
- Öztürk, Serkan(31)
- Sipahi, Ferkan(30)
- Kandemir, Raif(28)
- Arslan, Mehmet(27)
- Karsli, Orhan(27)
- Kulakaç, Nurşen(26)
- Baltacı, Cemalettin(25)
- Gücer, Mehmet Ali(25)
- Kurt, Kemal(25)
- Maden, Nafiz(25)
- Ozturk, Samet(25)
- Topal, Fevzi(25)
- Baltaci, Cemalettin(24)
- Yücel, Cem(24)
- Aliyazicioglu, Yuksel(23)
- Bayrakdaroglu, Serdar(23)
- Kankal, Murat(23)
- Peker, Iskender(23)
- Yolcu, Halil(23)
- Reis, Hatice Catal(21)
- Topal, Meryem(21)
- Vural, Alaaddin(21)
- Aydin, Aydanur(20)
- Aydin, Faruk(20)
- Bayraktar, Alemdar(20)
- Kurnaz, Muammer(20)
- Çelik, Necati(20)
- Ürkek, Bayram(20)
- Cakir, Tufan(18)
- Günen, Mehmet Akif(18)
Yayınlar
- MakaleAçık Erişim2011Solutions for 4D cadastre - with a case study on utility networks
Döner, Fatih; Thompson, Rod; Stoter, Jantien; Lemmen, Christiaan; Ploeger, Hendrik; van Oosterom, Peter; Zlatanova, Sisi
The increasing complexity and flexibility of modern land use requires that cadastres need to manage information on the third and temporal (fourth) dimension. This article considers the registration of legal space of utility networks in cadastre in this 3D + time (=4D) context. A requirement analysis in three countries that have methods to register utility networks complying with their legal, organizational and technical structure (Turkey, the Netherlands and Queensland, Australia) is the basis for three alternatives for 4D cadastre to register utility networks. The three alternatives are analysed with respect to legal, organizational and technical cadastral requirements. This article presents a case study and a prototype from the Netherlands. In this country by law utilities are considered to be real estate objects with obligatory registration of ownership and geometry. This study shows that the 3D space and separate temporal attributes approach (state-based model) is a very promising solution to maintain temporal changes of utility networks and that this approach is to be preferred above the current practice, where the 3D and temporal aspects are not considered when registering a network.
- MakaleAçık Erişim2011Quality characteristics of registered cultivars and advanced lines of durum wheats grown in different ecological regions of Turkey
Sakin, Mehmet A.; Sayaslan, Abdulvahit; Duzdemir, Oral; Yuksel, Ferhat
In this study, pastaquality- associated characteristics of 25 durum wheat genotypes were investigated. Durum wheat genotypes consisted of 13 advanced experimental lines and 12 registered cultivars that were grown in three different locations of Turkey for 2 yr. Genotype, location, year and their interactions were found to be statistically significant in terms of all investigated quality characteristics. Mean quality parameters for the genotypes varied as follows: yellowberry kernel 1.7-6.1%, pigment content 3.67-8.31 mg kg-1, lipoxygenase (LOX) activity 12.9-27.9 EU g-1, protein content 10.8-11.8% (14% mb), gluten index (GI) 12-61, sodium dodecyl sulphate-sedimentation volume 17.3-28.7 mL, specific sedimentation volume 1.60-2.52 mL. Of the genotypes, 10 contained γ-gliadin 45 and six γ-gliadin 42 proteins. Except for Zenit, none of the registered cultivars and advanced experimental lines investigated in this study were able to meet simultaneously the requirements for high-quality pasta products; yet certain experimental lines prevailing in specific quality characteristics, such as Line-Gdem- 2, Line-Gdem-12 and Line-20, may be used for further breeding purposes. The results of this study also imply that grain yield and quality should be taken collectively into consideration in wheat breeding programs.
- MakaleYalnız künye2011Characteristics of seismic activity in the Western, Central and Eastern parts of the North Anatolian Fault Zone, Turkey: Temporal and spatial analysis
Öztürk, Serkan
Characteristics of seismic activity along the North Anatolian Fault Zone are analyzed between 1970 and 2010. Magnitude completeness changes between 2.7 and 2.9 in the North Anatolian Fault Zone. The frequency-magnitude distribution of earthquakes is well represented with a b-value typically close to 1. A clear decrease in temporal distribution of b-value is observed before the strong main shocks. Correlation dimension values are relatively large and the seismic activity is more clustered at larger scales in the North Anatolian Fault Zone. A statistical assessment is made in order to detect the current seismic quiescence anomalies in the beginning of 2010. Eight significant anomalous zones throughout the North Anatolian Fault Zone are detected. These are centered at: (1) 41.08°N-28.58°E (around Silivri), (2) 41. 47°N-29.51°E (in the Black Sea), (3) 40.69°N-29.78°E (including Izmit), (4) 40.26°N-26.46°E (around Gelibolu, Canakkale), (5) 40.59°N-31.03°E (including Duzce fault), (6) 40.86°N-35.30°E (around Amasya), (7) 39.48°N-39.74°E (around Erzincan), and (8) 39.06°N-40.50°E (around Bingol).
- MakaleYalnız künye2011Effect of plant growth-promoting rhizobacteria and manure on yield and quality characteristics of Italian ryegrass under semi arid conditions
Yolcu, Halil; Turan, Metin; Lithourgidis, Anastasios; Çakmakçi, Ramazan; Koç, Ali
Plant growth-promoting rhizobacteria (PGPR) appeared as a promising alternative for organic fertilization. A field experiment was carried out to evaluate the effects of PGPR and solid cattle manure application on yield, quality, and mineral concentrations of Italian ryegrass (Lolium multiflorum Lam.) under semi arid conditions in Turkey. The treatments included: three manure application rates (i.e. M1, 10; M2, 20; and M3, 30 Mg ha -1), five PGPR strains (i.e. RC11, Bacillus subtilis; RC21, Variovorax paradoxus; RC105, Paenibacillus polymyxa; RP24/3, Paenibacillus polymyxa; and RF29/2, Pseudomonas putida), and a control (without bacteria or manure application). Manure application did not increase yield of Italian ryegrass, whereas the treatments with RC21 and RP24/3 rhizobacteria provided the highest dry matter yield. All PGPR and manure applications increased crude protein concentration of Italian ryegrass. The M3 manure rate and most treatments with PGPR (except RC11) produced greater crude protein yield than that of control. In addition, concentrations of P, S, Mg, Cu, Zn, and Fe in most PGPR and manure applications were greater than those of control.
- MakaleAçık Erişim2011In vitro inhibition of α-carbonic anhydrase isozymes by some phenolic compounds
Öztürk Sarikaya, Sevim Beyza; Topal, Fevzi; Şentürk, Murat; Gülin, Ihami; Supuran, Claudiu T.
Carbonic anhydrase inhibitors (CAIs) are a class of pharmaceuticals used as antiglaucoma agents, diuretics, antiepileptics, in the management of mountain sickness, gastric and duodenal ulcers, neurological disorders or osteoporosis. We report here the inhibitory capacities of some phenolic compounds against three human CA isozymes (hCA I, hCA II, and hCA VI) and the gill carbonic anhydrase of the teleost fish Dicentrarchus labrax (European seabass) (dCA). The isozymes showed quite diverse inhibition profiles with these compounds. These data may lead to design novel CAIs with a diverse inhibition mechanism compared to sulfonamide/sulfamate inhibitors.
- MakaleYalnız künye2011Total electricity and hydroelectric energy generation in Turkey: Projection and comparison
Akpinar, A.; Kömürcu, M.I.; Özölçer, I.H.; Şenol, A.
The main goal of this study is to forecast total electricity and hydroelectricity energy generation using historical electricity energy production data in order to determine the future level of electricity and hydroelectricity energy generation in Turkey. For this purpose, Turkey's electricity energy sector was reviewed during the period of 1940-2005. The total electricity and hydroelectricity energy generation were then modelled using historical energy generation data as years with regression analysis. Additionally, the portion that hydroelectric energy generation of Turkey has within total electricity energy production and probable meeting capacity of Turkey's hydroelectric potential of its future total demand was determined. According to the results, it is deduced that hydropower energy will have portion of 13.6% within the total electricity energy generation in 2030. In addition, it is concluded that the whole of Turkey's technical and economical hydroelectric energy potential that is equal 129.9 billion kWh will be used in the year of 2102 if the current trend continues.
- MakaleYalnız künye2011Investigation of water length effects on the modal behavior of a prototype arch dam using operational and analytical modal analyses
Sevim, Bariş; Bayraktar, Alemdar; Can Altunişik, Ahmet
This study determines the water length effects on the modal behavior of a prototype arch dam using Operational and Analytical Modal Analyses. Achievement of this purpose involves construction of a prototype arch dam-reservoir- foundation model under laboratory conditions. In the model, reservoir length was taken to be as much as three times the dam height. To determine the experimental dynamic characteristics of the arch dam using Operational Modal Analysis, ambient vibration tests were implemented for empty reservoir and three different reservoir water lengths. In the ambient vibration tests, the dam was vibrated by natural excitations provided from small impact effects and the response signals were measured using sensitive accelerometers. Operational Modal Analysis software process signals collected from the ambient vibration tests, and Enhanced Frequency Domain Decomposition and Stochastic Subspace Identification techniques estimated modal parameters of the dams. To validate the experimental results, 3D finite element model of the prototype arch dam was modeled by ANSYS software for empty reservoir and three different reservoir water lengths, and dynamic characteristics of each model were determined analytically. At the end of the study, experimentally and analytically identified dynamic characteristics compared to each other. Also, changes on the natural frequencies along to water length are plotted as graphs. Results suggest that reservoir water complicates the modal behavior of the arch dam significantly.
- BildiriYalnız künye2011A logic simplification based on expert system application for TBC diagnosis
Sümbül, Harun; Başçiftçi, Fatih; Lin, JC; Nikita, KS
Tuberculosis (TBC), caused by the bacterium My tuberculosis (Mtb), is a growing international health crisis [1]. TBC is one of the main causes of death produced by infectious illness and is responsible for almost 3 millions deaths every year [2]. In this study, a controlled Expert System (ES) have designed to diagnosis of TBC and truth table have created by considering the probabilities of TBC (12 symptom, 212=4096 different cases). According to the probabilities of TBC, 6 different cases have accepted as output values and reduced rule bases have obtained. These output values have been processed by an ES and have tried to diagnosis of TBC with help to ES. We obtained very good results and the results of analyses carried out indicated that controls performed with ES provide less time, less probability, reliable and consistent diagnosis and that are feasible in real life.
- MakaleYalnız künye2011The effects of some organic and chemical fertilizer applications on yield, morphology, quality and mineral content of common vetch (Vicia sativa L.)
Yolcu, Halil
A field experiment was conducted to evaluate the effects of some organic and chemical fertilizers on morphological, yield and quality properties and mineral contents of common vetch (Vicia sativa L.) between 2007 and 2008 in Gümüşhane, Turkey. Treatments were control (no fertilizer), liquid manure (LM = 51-52 L ha -1N), chemical fertilizer (CF = 30 kg N ha -1+ 80-100 kg P 2O 5ha -1), three leonardite doses (L 1= 2.8; L 2= 5.6 and L 3= 8.4 kg N ha -1), three zeolite doses (Z 1= 0.4; Z 2= 0.8 and Z 3= 1.2 N kg ha -1) and three solid cattle manure doses (SM 1= 34-35 kg N ha -1, SM 2= 68-70 kg N ha -1, SM 3= 102-105 kg N ha -1). Dry hay yield (DHY), leaf weight, stem weight, plant height, leaf number, crude protein content (CP), crude protein yield (CPY), acid detergent fiber (ADF), neutral detergent fiber (NDF), Ca, Fe, K, Mg, B, Cu, Mn, Na, Ni, P, Pb, S and Zn contents were determined. Organic and chemical fertilizer applications had significant effect (P<0.01) on DHY, leaf weight, stem weight, CP, CPY and mineral contents except leaf number, ADF and NDF in the both years. The plant height were significantly (P<0.05) affected by the treatments in the first year. The SM 2application in the first year and control and LM applications in the second year resulted to obtain improved yield components and crude protein yield. Z 2and Z 3applications also loomed large in terms of mineral contents.
- MakaleYalnız künye2011Aromatisation in adducts of a-terpinene: Influence of hindered internal Rotations
Kaya, Afşin Ahmet; Şengül, Mehmet Emin; Menzek, Abdullah; Kayaardi, Ibrahim; Karakuş, Murat; Şahin, Ertan
Each adduct of α-terpinene with p-quinone and 1,4-naphthoquinone in Ac2O/Et3N at 180 °C gives two aromatic products, one of which had a distinctive smell formed by the loss of an ethylene group. Here, we report the crystal structure of (1RS, 4RS)-1-isopropyl-4-methyl-1,4-dihydro- 1,4-ethanoanthracene-9,10-diyl diacetate. It is crystallised in an orthorhombic space group, Pbca, with cell dimensions a = 10.2899(7), b = 19.7804(9), c = 19.7519(8) Å and Z = 8. According to its NMR and X-ray diffraction data, the isopropyl and acetate groups slowly rotate.
- MakaleAçık Erişim2011The effect of material properties on the seismic performance of Arch Dams
Sevim, B.
The paper investigates the effect of material properties on the seismic performance of arch dam-reservoir-foundation interaction systems based on the Lagrangian approach using demand-capacity ratios. Type-5 arch dam is selected as a numerical application. The linear time history analyses of the arch dam-reservoir-foundation interaction system are carried out for different material properties. The foundation is taken into account as massless; behaviour of the reservoir is assumed to be linearly elastic, inviscid and irrotational. The north-south component of the Erzincan earthquake in 1992 is chosen as a ground motion. Dynamic equations of motions obtained from 3-D finite element modelling of the coupled system are solved by using the Newmark integration algorithm. The damage levels of the coupled system for the different material properties are demonstrated by using demand-capacity ratios and cumulative inelastic durations. The time histories and maximum values of the displacements and principal stresses, and performance curves, are obtained from linear analyses. It is clearly seen from the study that the different material properties affect the seismic behaviour of the dam.
- MakaleYalnız künye2011Restructuring of Turkey's electricity market and the share of hydropower energy: The case of the Eastern Black Sea Basin
Uzlu, Ergun; Akpinar, Adem; Kömürcü, Murat Ihsan
This paper presents the historical development of Turkey's electricity power sector, the efforts for introducing competition in the power industry in Turkey, and the concerns regarding restructuring in Turkey. The contribution of the hydropower energy potential in Turkey to the reconstruction of the electricity structure in Turkey is also investigated. Then, among the 25 hydrological basins in Turkey, the Eastern Black Sea Basin located in the northeast of Turkey, which has great advantages from the view point of small hydropower potential or hydropower potential without storage, is chosen as the case study to carry out some investigations concerning its potential and to analyze the contribution of the private sector (the corporate body) in regard to the development of hydro potential in this basin within the scope of the 4628 Electricity Market Law. With this law, concerning the restructuring of the electricity market, private sector investments in this segment have increased. In total, 1524 hydroelectric power projects with 22 360 MW installed capacity has been implemented until January 22nd, 2009 and this figure is continuously rising.
- MakaleYalnız künye2011The effect of fin pitch on heat transfer and fluid flow characteristics in the entrance region of a finned concentric passage
Kuvvet, Kemal; Yavuz, Tahir
In this study, the heat transfer and fluid flow characteristics in the unfinned and internally finned concentric passage (smooth and finned annulus) are investigated experimentally. The turbulence characteristics, mean flow, pressure drop and heat-transfer parameters in the entrance region of a concentric passage of diameter ratio 0.2 are measured. The hot-wire anemometer and the liquid-crystal technique are used for the turbulence and mean flow and the heat transfer measurements, respectively. The finned passage is designed as the fin width (W) of 2 mm, the fin height (H) of 2, 4, 6 and 8 mm and the fin pitch (P) of 20, 30 and 40 mm. Reynolds number ranges from 1.8 .104 to 1.24.105 and from 1.65.104 to 7.65.104 for flow and pressure drop and heat transfer measurements, respectively. Experiments are performed for the smooth and finned concentric passages by varying flow and fin parameters and the effects of the fin pitch are investigated. The developing of fluid flow is analyzed and the variation of turbulence intensity, friction factors, local and mean convective heat transfer coefficients in the smooth and finned concentric passages are obtained. Results obtained in the finned concentric passages are compared with the results of the smooth passage. For the average Nusselt numbers and friction factor, empirical equations are developed. As a result, it is seen that the friction factor in the finned passage increases between 3.61 and 18.05 times while the average Nusselt number augments between 1.36 and 5.23 times on the inner surface and between 1.03 and 1.80 times on the outer surface.
- MakaleYalnız künye2011Determination of seasonal changes in olive oil by using differential scanning calorimetry heating thermograms
Ilyasoglu, Huri; Ozcelik, Beraat
Thermal properties (upon heating) of extra virgin olive oils (EVOOs) from Aegean cultivars were determined to evaluate the possibility of using differential scanning calorimetry (DSC) as a tool for monitoring seasonal changes in chemical composition. Chemical properties of the samples were analyzed to assess the relationship between the thermal properties and chemical properties as well. The thermal properties of Aegean cultivars were found to be influenced by major components (palmitic acid, oleic acid, linoleic acid, triolein and palmitodiolein). The melting offset temperature, the temperature range of melting and the melting enthalpy of Aegean cultivars presented significant differences with respect to crop season (p < 0.05). DSC may be utilized to evaluate compositional changes with respect to crop season.
- MakaleYalnız künye2011Petrochemistry and U-Pb zircon ages of adakitic intrusions from the pulur massif (eastern pontides, ne Turkey): Implications for slab rollback and ridge subduction associated with Cenozoic convergent tectonics in the eastern Mediterranean
Eyuboglu, Yener; Santosh, M.; Chung, Sun-Lin
The well-preserved magmatic arc in the eastern Pontides orogenic belt of northeastern Turkey offers critical clues on convergent margin tectonics associated with the late Mesozoic-early Cenozoic geodynamic evolution of the eastern Mediterranean region. Here we investigate the petrology, geochemistry, and U-Pb zircon chronology of adakitic intrusions from the Pulur region in the southern zone of the eastern Pontides belt. The intermediate to felsic intrusives in the Pulur region are characterized by the presence of abundant plagioclase, amphibole, and biotite phenocrysts. The rocks display extreme light rare earth element enrichment (LaN YbN p13.69-51.08); high Al2O3 (15.46-17.47 N Nwt%), Na2O (3.57-8.43 wt%), Sr (324.8-1468 ppm), and La (13.9-55.8 ppm) concentrations; a high Sr/Y ratio (35-473); and low Y (3-12.6 ppm) and heavy rare earth element concentrations, closely comparing with the typical features of adakites. Zircons extracted from the Pulur adakites show euhedral crystal shapes, oscillatory zoning patterns, andhigh Th/U ratios (up to 3.33) consistent with their magmatic origin. Their 206Pb/238U ages show a range of 55.21-53.07 Ma, correlating the magmatism to the early Eocene. We propose a tectonic model involving the initiation of a slab rollback and simultaneous opening of a slab window during ridge subduction in a south-dipping sub duction zone for the origin of the Tertiary adakitic and nonadakitic magmatism in the eastern Pontides orogenic belt. We also identify a close relation between slab rollback processes and back arc extension, which led to the opening of the Tertiary basins in the southern part of the eastern Pontide orogenic belt. The eastern Pontide orogenic belt is one of the world's largest metallogenic provinces, and it hosts various economic mine ralizations such as volcanogenic massive sulfide, epithermal gold-silver, porphyry copper-molybdenum, skarn-type, and chromite. However, the adakitic intrusions exposed in the southern part of the eastern Pontide orogenic belt are devoid of ore deposits, which leads us to propose that the Lutetian or later nonadakitic granitic intrusions exposed at the north of the Gumushane-Bayburt-Ispir line were probably responsible for the epithermal gold mineralization in this belt.
- MakaleYalnız künye2011Mild and severe anal incontinence after lateral internal sphincterotomy: Risk factors, postoperative anatomical findings and quality of life
Kement, M.; Karabulut, M.; Gezen, F.C.; Demirbas, S.; Vural, S.; Oncel, M.
Aim: This study aims to evaluate the risk factors for incontinence after lateral internal sphincterotomy (LIS) and assess quality of life in different levels of incontinence. Methods: All consecutive patients (n = 253) with chronic anal fissure who underwent LIS between 2003 and 2006 were retrospectively reviewed. All patients were questioned for possible anal incontinence according to the Wexner Incontinence Score (WIS). Demographics, vaginal delivery history, additional procedures and surgeon's experience were evaluated as risk factors. Endoanal ultrasound (EUS) was performed in incontinent patients to assess the thickness of the remaining internal sphincter and to evaluate any injury in the external sphincter. Quality of life was questioned with SF-36. Results: Twenty-eight (11.7%) patients suffered from incontinence (mean WIS = 3.6 ± 2.5). The search for a risk factor was unsuccessful when continent and incontinent groups were compared. In subgroup analyses, patients were found to be suffering from mild (WIS <5, n = 19) or severe (WIS >5, n = 9) incontinence. Vaginal delivery history was found more often in the severely incontinent subgroup than in the continent group (p < 0.05). Also, vaginal delivery history and the additional procedures were more frequently observed in the severely incontinent subgroup than in the mildly incontinent subgroup. EUS did not find any external sphincter injury in these cases. WIS had negative correlations with the physical and mental component scores of SF-36. Conclusion: In our opinion, the threat for incontinence is unpredictable; however, vaginal delivery history may increase the risk of severe incontinence.
- MakaleYalnız künye2011Finite element model calibration of berke arch dam using operational modal testing
Sevim, Bariş; Bayraktar, Alemdar; Altunişik, Ahmet Can
This paper presents the finite element calibration of Berke Arch Dam by using Operational Modal Testing. Achievement of this purpose involves structural vibration characteristics of Berke Arch Dam using analytical and Operational Modal Analyses. Therefore, the study has two parts-analytical and experimental. In the analytical part of the study, the authors developed a 3D finite element model of Berke Arch Dam-reservoir-foundation system using ANSYS software, and analytically determined vibration characteristics such as natural frequencies and mode shapes. In the experimental part of the study, sensitive accelerometers were placed to several points of Berke Arch Dam, and ambient vibration tests were conducted over four days to obtain dynamic characteristics. The Enhanced Frequency Domain Decomposition technique is used to estimate natural frequencies, mode shapes and damping ratios of the Berke Arch Dam experimentally. Results showed that there were some differences between analytical and experimental natural frequencies of the dam. Therefore, an analytical model of Berke Arch Dam was calibrated to minimize these differences by changing material properties. Analytical results obtained from the calibrated model mainly conform to those of the experimental model.
- MakaleYalnız künye2011Solid waste management practices in Turkey
Berkun, Mehmet; Aras, Egemen; Anılan, Tugce
As an economically developing country, Turkey has very well operated integrated solid waste management applications structured on modern facilities, besides over 2,000 scattered open dump areas in the country. Integrated waste management applications seem eligible for the metropolitan cities like Istanbul and Izmit (Kocaeli). Attempts have not been encouraging for the scattered regional settlements using central storage sites due to financial shortages and received rejections from nearby settlements. Small-scale compact solid waste management systems with materials recycling and composting can be more suitable alternatives in the small-scale regional settlements. The major constituents of municipal solid waste are organic in nature and approximately a quarter of municipal solid waste is recyclable. Although paper, including cardboard, is the main constituent, the composition of recyclable waste varies strongly by the source or the type of collection point. Solid wastes need primary treatment in order to be suitable for incineration and composting. Turkey needs to give more emphasis on the usage of modern solid waste removal technologies to overcome the overgrowing solid waste disposal problems.
- BildiriYalnız künye2011Hydroxyapatite production on ultrafine-grained pure titanium by micro-arc oxidation and hydrothermal treatment
Alsaran, A.; Purcek, G.; Hacisalihoglu, I.; Vangolu, Y.; Bayrak, O.; Karaman, I.; Celik, A.
In this study, pure-Ti (Grade-2) was severely plastically deformed by equal-channel angular extrusion (ECAE) to improve its strength, and then subjected to micro arc oxidation (MAO) and hydrothermal treatment (HT) to achieve improved surface behavior with hydroxyapatite (HA)-containing titania (TiO(2)) coating. Microstructure, tensile properties and wear behavior of UFG Ti were investigated systematically before and after surface modification. ECAE considerably enhanced the strength of coarse-grained (CG) Ti by forming an ultra-fine grained (UFG) microstructure with high dislocation density. The application of MAO with or without HT did not cause remarkable decrease in strength and ductility of CG and UFG Ti, but resulted in a considerable increase in its wear resistance and osseointegration due to the formation of hard and adhered HA-containing TiO2 coating on the surface. It can be concluded that the use of ECAE plus MAO/HA coating provides a simple and effective procedure to obtain pure Ti with high strength and high wear resistance. The improved bulk and surface properties can make this biocompatible material a good potential candidate for biomedical applications instead of alloys including toxic elements. (C) 2011 Elsevier B.V. All rights reserved.
- MakaleAçık Erişim2011Transition from shoshonitic to adakitic magmatism in the eastern Pontides, NE Turkey: Implications for slab window melting
Eyuboglu, Yener; Chung, Sun-Lin; Santosh, M.; Dudas, Francis O.; Akaryali, Enver
The formation of the eastern Pontides orogenic belt has been widely assigned to a northward subduction of the Neotethyan oceanic slab during the late Mesozoic-Cenozoic. Here we provide an alternate model based on new geological, geochemical and isotopic data. The magmatic activity in the far south of the belt started in the early Campanian with shoshonitic trachyandesites and associated pyroclastics. This sequence is covered by the late Campanian-early Maastrichtian reefal limestones and another stage of high-K volcanism represented by analcimized leucite-rich ultrapotassic rocks of the Maastrichtian-early Paleocene (?) ages. The shoshonitic and ultrapotassic rocks, with K2O contents ranging from 0.26 to 6.95 wt.%, display broadly similar rare earth and multi-element distribution patterns. Both rock types are enriched in LILE and LREE and depleted in HFSE (Nb,Ta and Ti), suggesting a subduction-enriched mantle source for the magma generation. Subsequently, during the late Paleocene, a stage of acidic magmatism (SiO2 of 53.25-73.61 wt.%) that shows adakitic geochemical characteristics including high Sr/Y (46-416) and La/Yb (11-51) and low Y (2.6-12.2 ppm), is documented characterized by melting of a mafic source such as the MORB crust with garnet in the residue. The adakitic magmatism began at similar to 56 Ma and migrated toward the north through time, culminating with porphyritic andesites (similar to 47 Ma) that were emplaced in the Gumushane-Bayburt line and its vicinity. North of this line, coeval magmas show typical calc-alkaline nature and continued to develop toward further north until the middle to late Eocene. Based on the spatial and temporal variations in the magmas generated in the eastern Pontides orogenic belt, we propose a new geodynamic model to explain the tectonomagmatic evolution of these rocks and correlate the adakitic magmatism to ridge subduction and slab window process within a south-dipping subduction zone. Our model is in contrast to the previous proposals which envisage partial melting or delamination of thickened lower continental crust due to the collision in the south during the Paleocene-Eocene. (C) 2010 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.