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
- MakaleYalnız künye2011Adakite-like granitoid porphyries in the Eastern Pontides, NE Turkey: Potential parental melts and geodynamic implications
Karsli, Orhan; Ketenci, Murat; Uysal, Ibrahim; Dokuz, Abdurrahman; Aydin, Faruk; Chen, Bin; Kandemir, Raif; Wijbrans, Jan
The tectonic setting of the Eastern Pontides during the late Mesozoic to early Cenozoic remains a subject of debate. Petrogenesis of adakite-like granitoid porphyries plays a critical role in determining the nature of the lower continental crust and mantle dynamics during orogenic processes in the region. Here we describe, for the first time, the late Paleocene to early Eocene adakite-like granitoid porphyries from the northern part of the Eastern Pontides although their counterparts in the southern part have recently been found. The adakitic porphyries, which emplaced into the subduction-related Turonian-Santonian volcanics from northern part of the region, consist of I-type calc-alkaline quartz monzonite-tonalite (SiO2 = 62.89-65.07 wt.%) and high-k calc-alkaline granodiorite-granite associations (SiO2 = 69.06-70.43 wt.%). The former displays peraluminous to metaluminous signatures, whereas the latter shows peraluminous geochemical character. The granite-granodiorite porphyries have high K2O (3.32-3.84 wt.%), and low Na2O (3.48-4.61 wt.%) and MgO (0.91-1.04 wt.%) relative to the quartz monzonite-tonalite association (K2O = 1.50-1.92 wt.%; Na2O = 4.08-6.45 wt.%; MgO = 1.44-2.07 wt.%). Ar-Ar geochronology studies on the amphibole separates reveal that the adakite-like porphyries have a crystallization ages of 51.34 +/- 0.27 to 53.55 +/- 0.34 Ma. Here, we contend that these rocks were formed by partial fusion of a mafic lower continental crust in a collisional phase but not in a subduction setting. All the samples exhibit the typical geochemical characteristics of adakite, that is, high Sr (250-1141 ppm), high Sr/Y ratios (16-147), low Y (6.8-14.8 ppm) and low HREE concentrations; they are similar to adakites formed by slab melting associated with the subduction zone. However, the rocks exhibit heterogeneity in isotopic composition, with I-Sr ranging from 0.70554 to 0.70986, epsilon(Nd) (51 Ma) from -8.5 to -0.9 and Nd model ages from 0.72 to 1.26 Ga. The samples are characterized by relatively high Th, Th/U and no significant Eu anomalies, implying that garnet was stable in their source during partial melting. The compositional diversity between rock groups is probably related to partial melting of heterogeneous lower crustal source. All of the features are inconsistent with a slab-melting origin and slab-related petrogenetic model, but instead, they favor an origin by melting of heterogeneous lower continental crust due to a thermal anomaly that was induced by the upwelling of the asthenosphere through a slab break-off in a collisional setting. These interpretations argue against the evidence for the presence of an early Cenozoic arc setting in the Eastern Pontides. Instead, the early Cenozoic time in the region may be attributed to a geodynamic response to a post-collisional uplift phase that occurred along the continent-continent collision between the Pontide and the Anatolide-Tauride blocks. (C) 2011 Elsevier B.V. All rights reserved.
- MakaleYalnız künye2011Migrating magmatism in a continental arc: Geodynamics of the Eastern Mediterranean revisited
Eyuboglu, Yener; Santosh, M.; Dudas, Francis O.; Chung, Sun-Lin; Akaryali, Enver
The eastern Pontide orogenic belt in Turkey offers a critical region to evaluate the geodynamic evolution of the eastern Mediterranean region during the late Mesozoic-Cenozoic. Here we synthesize results from our exhaustive database on the geochemical characteristics of adakitic magmatism from 137 bodies covering 7 domains in the southern zone of eastern Pontides. Together with new Pb-Sr-Nd results, we show that the adakitic magmatism in the eastern Pontide belt is clearly linked to slab window processes during ridge subduction, as against the earlier models that assumed partial melting of a delaminated or thickened lower continental crust following collision. The isotopic compositions display a complex pattern and suggest mixing of multiple source materials such as depleted mantle, enriched lithospheric mantle, and upper crust. We also confirm a southward polarity of subduction as against the previous models that assumed a northward subduction. We supplement our model with evidence for a northward propagation of the adakitic magmatism, spatial and temporal variations in arc magmatism, presence of south-dipping reverse faults and a synthesis of the available paleomagnetic data. Our studies also suggest that the Black-Sea is a remnant of the Tethyan ocean that was situated to the north of the arc during the late Mesozoic-Cenozoic as against the correlation to a late Mesozoic-Cenozoic back-arc basin related to a northward subduction of the Paleo- or Neo-tethyan oceanic lithosphere in alternate models. (C) 2010 Elsevier Ltd. All rights reserved.
- MakaleAçık Erişim2010Combination technique of tumescent anesthesia during endovenous laser therapy of saphenous vein insufficiency
Memetoglu, Mehmet Erdem; Kurtcan, Serpil; Kalkan, Asim; Özel, Deniz
Objective: This study aimed at evaluating the efficiency of applying tumescent anesthesia before an ablation procedure and continuously during endovenous laser treatment (EVLT) (combined tumescent technique) of saphenous vein insufficiency to reduce the patients pain and discomfort. Methods: Twenty-five patients with 31 duplex-confirmed great saphenous vein insufficiency underwent endovenous laser (940 nm) varicose vein treatment between December 2009 and April 2010. The patients were randomized in two groups. In group A (15 patients) tumescent anesthesia was used before the ablation procedure and in group B (10 patients) tumescent anesthesia was used before and continuously during the procedure. Patients were scheduled for a three-day examination after EVLT to assess the level of pain experienced. Results: According to the statistic analysis we observed that the mean level of pain score for the patients given classical tumescent anesthesia showed a higher level (P=0.003) compared with the patients given tumescent anesthesia in the combined procedure. Conclusion: Combination technique of administering tumescent anesthesia before ablation and continuously during the EVLT procedure may be an alternative way to reduce the patient's peroperative pain and discomfort. (C) 2010 Published by European Association for Cardio-Thoracic Surgery. All rights reserved.
- MakaleAçık Erişim2010The Relationship Between Knee Osteoarthritis and Osteoporosis
Sezer, Ilhan; Illeez, Ozge G.; Tuna, Serpil D.; Balci, Nilufer
Objective: The aim of this study was to investigate the association between knee osteoarthritis (OA) and bone mineral density (BMD) in the femur and lumbar vertebrae. Materials and Methods: A total of 74 female patients (mean age 61.9 +/- 9.1 years, mean body mass index 27.09 +/- 4.24) diagnosed with knee OA were included in this study. To assess knee OA, bilateral weight-bearing antero-posterior knee radiographs were taken and graded from 0 to 4 according to Kellgren-Lawrence criteria. The BMD of the subjects was measured using dual-energy X-ray absorptiometry (DEXA). BMD measurements of those with OA were compared with those without OA. Results: While there was no correlation between BMD and the grade of knee OA, a significant negative correlation was found between age and femur BMD. Body mass index was positively correlated with OA and negatively correlated with OP. Conclusion: Further investigations are needed to demonstrate the association between knee OA and BMD.
- MakaleAçık Erişim201017,18-Dibromo-8-methyl-4,12-ditosyl-3,4,5,6,7,8,9,10,11,12,13,14-dodecahydro-2H-benzo[b][1,4,7,11,15]dioxatriazacycloheptadecine
Kelesoglu, Zeynep; Kaya, Elif Celenk; Kantekin, Halit; Bueyuekguengoer, Orhan
In the title compound, C31H39Br2N3O6S2, a 17-membered aza-macrocyclic ligand containing two ether O and three aza N atoms, the three pendant aromatic rings form an 'E' shape. The dihedral angles between the central benzene ring and the side ones are 17.8 (3) and 7.4 (3)degrees , and the dihedral angle between the tosyl rings is 10.6 (3)degrees . The methyl group is disordered over two orientations, with occupancies of 0.52 (15) and 0.48 (15).
- MakaleYalnız künye2010The Alteration Mineralogy and Mass Change of the Zigana (Gumushane) Volcanics of NE Turkey
Sipahi, Ferkan; Sadiklar, M. Burhan
The Late Cretaceous volcanic rocks around Zigana Mountain (Gumushane) in the eastern Black Sea metallogenic province in NE Turkey show intensive hydrothermal alteration but less weathering alteration. The basement of the study area is formed by Late Cretaceous basalt, andesite and their pyroclastics. These rocks are overlain by dacitic rocks of the same age, namely Dacite-I and Dacite-II. These volcanic rocks are bimodal in character and have developed in a volcanic arc environment. The volcanic rocks in the study area have been altered to the sericite/illite-chlorite facieses, and contain sericite/illite, chlorite, quartz, carbonate minerals (ankerite and calcite), iron-oxide, and rare kaolinite, smectite and epidote as the products of alteration. Sericitization/illitization is the most common type of hydrothermal alteration associated with these volcanics, and chloritization is the most common alteration type after illitization; pyritisation is seen in all volcanics, and is the most common in dacites. In some fields limonitisation is occasionally present. Epidotization is rare, and especially seen in basalt and andesite. Isocon analysis was undertaken to estimate the mass gains and losses of the Zigana Volcanics as a result of hydrothermal alteration. In general terms, the results shows that, basalt and andesite have 2-61% mass gain, Dacite-I 71% mass gain and 42 % mass loss, and Dacite-II 44% mass gain and 32% mass loss. Namely, both mass gain and mass loss occurred in the volcanics during the hydrothermal alteration of the parent materials. From less altered rock to highly altered rock there was an increase in illite-chlorite-kaolinite whereas there was a decrease in carbonate minerals. In the volcanics, fluids which cause sericitization and chloritization did not increase metals like Cu, Pb and Zn and, in fact, it can be said that these fluids are poor in point of these metals. This also shows that the metals developed under different hydrothermal conditions.
- MakaleYalnız künye2010The synthesis and characterization of metal-free and metallophthalocyanine polymers by microwave irradiation containing diazadithia macrocyclic moieties
Kaya, Elif Celenk; Karadeniz, Huelya; Kantekin, Halit
A tetranitrile monomer was synthesized by nucleophilic aromatic substitution of N,N'-(2,2'-(propane-1,3-diylbis(sulfanediyl))bis(ethane-2,1-diyl))bis(4-methylbenzenesulfonamide) onto 4-nitrophthalonitrile. A metal-free phthalocyanine polymer was prepared by the reaction of the tetranitrile monomer under N-2 in the presence of 2-(dimethylamino)ethanol at 145 degrees C for 24 h. Zinc(II), copper(II), cobalt(II), nickel(II), lead (II), phthalocyanine polymers were prepared by reaction of the tetranitrile with the chlorides of zinc (II), copper (II), cobalt (II), nickel (II), lead (II), employing microwave irradiation in the presence 2-(dimethylamino)ethanol at 175 degrees C, 350 W for 10 min. The thermal stabilities of the phthalocyanine compounds were determined by thermogravimetric analysis. The new compounds were characterized by a combination of IR, H-1 NMR, C-13 NMR, UV-vis, elemental analysis and MS spectral data. (C) 2009 Elsevier Ltd. All rights reserved.
- MakaleYalnız künye2010Liquefaction of cotton stalks (Gossypium hirsutuml.) with phenol
Fidan, M.Said; Alma, M.Hakki; Bektas, Ibrahim
In this study, we aimed to synthesize resol type wood adhesive from resinification of cotton stalk liquefied into phenol in the presence of sulfuric acid as catalyst. The biomass was first liquefied with phenol in the presence of sulfuric acid as a catalyst at various reaction conditions. It was detected that increasing acid concentration, temperature and time resulted in a great decrease on the amount of unliquefied cotton stalks and a significant increase in the percentage of combined phenol in the produced resin. It was also found out that the resin produced from cotton stalks can be perfectly used in the production of wood composite materials.
- MakaleAçık Erişim2010Structure and geochemistry of an Alaskan-type ultramafic-mafic complex in the Eastern Pontides, NE Turkey
Eyuboglu, Yener; Dilek, Yildirim; Bozkurt, Erdin; Bektas, Osman; Rojay, Bora; Sen, Cuneyt
The Karayasmak ultramafic-mafic association (KUMA) in NE Turkey represents an Alaskan-type, pre-Liassic intrusion in the Pulur metamorphic massif and is one of many such intrusive complexes that were emplaced into the continental basement of the Eastern Pontides belt during the pre-Liassic. Its main lithological units include plagioclase peridotite, melagabbronorite, banded gabbro and anorthosite (Phase-I), gabbro-pegmatite dikes (Phase-II), unmetamorphosed banded gabbro (Phase-III), cumulate olivine gabbronorite (Phase-IV), and non-cumulate gabbroic dikes and stocks (Phase-V). The contact relations between these units are gradational or intrusive, with the peridotites (Phase-I) enveloping the cumulate gabbronorites (Phase-IV) in the center of the elliptical body, displaying a concentric reverse-zoning pattern. Cr-Al spinel, plagioclase, and olivine are the first crystallizing phases in all cumulate rocks, whereas pyroxene, hornblende, phlogopite, magnetite, and ilmenite represent the intercumulus phases. The existence of hornblende and phlogopite, the high Wo and Cr2O3 contents of clinopyroxene, and the high Fo and NiO contents of olivine indicate that the KUMA units were the near-liquidus fractional crystallization products of hydrous basaltic magma. The Phase-I and Phase-III cumulates are slightly enriched in LILE and LREE, depleted in HFSE and HREE with respect to chondrite and primitive mantle, and show negative Nb, Zr, Hf and Ti anomalies. The Phase-IV cumulate gabbronorites are even more enriched in LILE and LREE and show less depletion in HFSE and HREE in comparison to the earlier phases. The KUMA units formed from high-Al hydrous basaltic magmas, which were derived from partial melting of a previously subduction-metasomatized subcontinental-lithospheric mantle. These magmas underwent crystal fractionation and mineral concentration processes in small magma chamber(s) at shallow crustal levels (< 5 kbar).
- MakaleYalnız künye2010Consumer perceptions of organic foods in Turkey
Ilyasoǧlu, Huri; Temel, Sara; Özçelik, Beraat
This study presents the results of a survey regarding consumer perceptions of organic foods in Turkey. The survey was conducted to determine consumer attitudes towards organic foods and the reasons for consumption or non-consumption of organic foods. A total of 383 consumers from different occupational groups living in Istanbul participated in the research. The results of the survey revealed that more than half of the survey participants had knowledge about organic foods. The majority of the participants were positive towards organic foods and purchased them as well. The results of chi-square analysis showed that the consumption of organic foods varied with respect to gender, job and education. Women and more educated participants tend to buy organic foods more than other participants. In market, fruits and vegetables, cereals and legumes, dried fruits and dairy products were organic products recognized by consumers. The main organic products purchased by consumers were fruits and vegetables. The results of the survey also indicated that the participants confidence in organic foods was at moderate level. About 37% of the participants was found to rely on organic foods and about 49% of the participants were unsure about organic foods. Organic foods were purchased because they were perceived as healthy, environmentally friendly and more nutritious than conventional foods. However, the consumption of organic foods was found to be lower. The majority of the participants stated that they consumed organic foods rarely or sometimes. Price and lack of availability of organic foods were barriers to increase the consumption of organic foods.
- MakaleYalnız künye2010Generation of the Early Cenozoic adakitic volcanism by partial melting of mafic lower crust, Eastern Turkey: Implications for crustal thickening to delamination
Karsli, Orhan; Dokuz, Abdurrahman; Uysal, Ibrahim; Aydin, Faruk; Kandemir, Raif; Wijbrans, Jan
Early Cenozoic (48-50 Ma) adakitic volcanic rocks from the Eastern Pontides, NE Turkey, consist of calc-alkaline and high-K calc-alkaline andesite and dacite, with SiO2 contents ranging from 56.01 to 65.44 wt.%. This is the first time that Early Eocene volcanism and adakites have been reported from the region. The rocks are composed of plagioclase, amphibole, quartz, and Mg-rich biotite. They have high and low-Mg# values ranging from 55 to 62 and 13 to 42, respectively. High-Mg# rocks have higher Ni and Co contents than low-Mg# samples. The rocks exhibit enrichments in large ion lithophile elements including the light rare earth elements, depletions in Nb, Ta and Ti and have high La/Yb and Sr/Y ratios. Their relative high ISr (0.70474-0.70640) and low εNd (50 Ma) values (- 2.3 to 0.8) are inconsistent with an origin as partial melts of a subducted oceanic slab. Combined major- and trace element and Sr-Nd isotope data suggest that the adakitic magmas are related to the unique tectonic setting of this region, where a transition from a collision to an extension stage has created thickening and delamination of the Pontide mafic lower crust at 50 Ma. The high-Mg adakitic magmas resulted from partial melting of the delaminated eclogitic mafic lower crust that sank into the relatively hot subcrustal mantle, and its subsequent interaction with the mantle peridotite during upward transport, leaving garnet as the residual phase, elevates the MgO content and Mg# of the magmas, whereas low-Mg# magmas formed by the melting of newly exposed lower crustal rocks caused by asthenospheric upwelling, which supplies heat flux to the lower crust. The data also suggest that the mafic lower continental crust beneath the region was thickened between the Late Cretaceous and the Late Paleocene and delaminated during Late Paleocene to Early Eocene time, which coincides with the initial stage of crustal thinning caused by crustal extensional events in the Eastern Pontides and rules out the possibility of an extensional regime before ~ 50 Ma in the region during the Late Mesozoic to Early Cenozoic.
- MakaleYalnız künye2010Prognostic significance of perineural invasion in patients with gastric cancer who underwent curative resection
Bilici, Ahmet; Seker, Mesut; Ustaalioglu, Bala Basak Oven; Kefeli, Umut; Yildirim, Emre; Yavuzer, Dilek; Aydin, Fatih Muhammed; Salepci, Taflan; Oncel, Mustafa; Gumus, Mahmut
Background: The prognostic significance of perineural invasion (PNI) in gastric cancer has been previously investigated in a few studies, but had not reached a consensus. The aim of this study was to determine the prognostic value of PNI in patients with gastric cancer who underwent curative resection. Materials and Methods: We retrospectively analyzed 238 patients who had undergone curative gastrectomy. Paraffin sections of surgical specimens from all patients were stained with hematoxylin and eosin. PNI was defined when carcinoma cells infiltrated into the perineurium or neural fascicles. PNI and the other prognostic factors were evaluated by univariate and multivariate analysis. Results: PNI was detected as positive in 180 of the 238 patients (75.6%). pT stage, tumor size, lymph node metastasis, clinical stage, tumor differentiation, Borrmann classification, histological type, lymphatic vessel invasion, and blood vessel invasion were closely associated with the presence of PNI. The PNI-positive tumors had significantly larger size and more lymph node metastasis than the PNI-negative tumors (P =.001 and P <.001, respectively). The median survival of the PNI-positive patients was significantly worse than that of the PNI-negative patients (28.1 vs. 64.9 months, P =.001). Multivariate analysis indicated that the positivity of PNI was an independent prognostic factor (P =.02, hazard ratio [HR]: 2.75; 95% confidence interval [95% CI]:1.12-3.13) as were classical clinicopathological features. Conclusion: Our results showed that the frequency of PNI was high in patients with gastric cancer who underwent curative gastrectomy and the proportion of PNI positivity increased with progression and clinical stage of disease. PNI may be useful in detecting patients who had poor prognosis after curative resection in gastric cancer.
- MakaleYalnız künye2010Responses of some wheat genotypes and their F2 progenies to salinity and heat stress
Yildirim, Mehmet; Bahar, Bilge
Both heat and salinity cause yield decrease in wheat. Grain yield in wheat has increased as a result of breeding efforts for different stress conditions. However, there are still substantial opportunities to improve grain yield by using conventional breeding under stress conditions, like heat and salt stress. The objective of this study was to investigate heat and salt effects on yield and some agronomic traits of four wheat genotypes and their six half F2 diallel cross progenies grown in pots. Significant differences were found among the genotypes for grain yield under both heat stress and non-stress condition. There was a mean reduction in yield of 12.6% due to salt stress. The reduction in biomass was higher than grain yield under salt stress while it was lower at heat stress. Grain yield was positively correlated with spike weight, harvest index, grain numbers per plant and biological yield under non stress (NS), heat stress (HS) and salt stress (SS) conditions. Cultivars Seri 82 and Chil's had high yield among parents under both NS and SS. Chil's and its hybrids showed low reduction in yield due to SS; thus, exhibiting salt tolerance. Also, Chil's was found to be good combiner with high General Combining Ability (GCA) effects for grain yield under SS conditions. 84 CZT04 was the most susceptible cultivar under SS. Significant GCA effects of Genç 99 and 84CZT04 provided positive contribution to grain yield under HS. It was impossible to select both heat and salt tolerant genotype with high yield capacity from the used genotypes. However, heat or salt tolerant genotypes can be improved by selection breeding due to genetic variation among genotypes.
- MakaleYalnız künye2010Late Cretaceous high-K volcanism in the eastern Pontide orogenic belt: Implications for the geodynamic evolution of NE Turkey
Eyüboǧlu, Yener
High-K volcanics were produced in two different Late Cretaceous cycles during the infilling of back-arc basins of the eastern Pontides. The first cycle, represented by shoshonitic trachyandesites and associated pyroclastics, containing high K2O (2.74-4.81 wt-%) and NaK2O (3.60-5.51 wt-%), overlies a mid-Cretaceous ophiolitic-olistostromal melange formed during the rifting stage of a back-arc basin (Neotethys). 40Ar39Ar dating of biotite from trachyandesite at the base of the first cyle indicates that shoshonitic volcanism in the far south of the eastern Pontides started in the early Campanian. Volcanic rocks of this cycle are overlain by upper Campanian-Maastrichtian rudist-bearing reefal limestones. The second cycle of high-K volcanism is represented by analcime-bearing volcanic rocks erupted in a Neotethyan lagoonal environment. These volcanic rocks, intercalated with continental detritus, are characterized by high a2O (3.22-7.16 wt-%), now concentrated in secondary analcime crystals. Their K2O contents also range between 0.83 and 6.05 (wt-%). All of these units are disconformably overlain by Eocene turbidites with a basal conglomerate. Volcanic rocks belonging to both cycles show various enrichment degrees in LILE, HFSE, LREE, and HREE with respect to primitive mantle and chondrite [(La/Lu) cn=11.10-25.89]. Negative Nb, Ta, Zr, Hf, and Ti anomalies are typical of these subduction-related arc magmas. Geochemical similarities between the two volcanic cycles suggest that trachyandesites and analcime-bearing volcanics were derived from similar enriched mantle sources, and that they formed in the same geotectonic setting of a back-arc basin environment of the eastern Pontide magmatic arc during the Late Cretaceous. In addition, Nd-Sr and Pb isotope ratios of the investigated volcanic units indicate that their mantle melt sources were similar. The new geological, geochemical and isotopic data suggest that southward subduction of the Palaeotethyan oceanic crust can be separated into two main stages for the late Mesozoic Pontide orogenic belt. Early southward subduction ended by slab break-off during the mid-Cretaceous, resulting in upwelling and injection of asthenospheric mantle that caused the opening of the eastern Pontide back-arc basin (Neotethys). Resumption of southward subduction began with intense TH-CA bimodal volcanism in the northern front of the arc during the Turonian-Coniacian. The intensity of this Late Cretaceous magmatism in the north decreased towards the south, and a transition to monogenic calcalkaline-alkaline (CA-A) Campanian andesitic volcanism developed in the southern zone. Yet farther south, andesitic igneous activity graded into the Campanian-Maastrichtian shoshonitic and ultrapotassic volcanism in the Bayburt-Maden, Tokat, Amasya, and Gümüshaciköy areas. This zoning of the Late Cretaceous arc magmatism (TH-CA, CA-A and shoshonitic-ultrapotassic, from north to south) also supports the concept of southward subduction during late Mesozoic evolution of the eastern Mediterranean region.
- MakaleYalnız künye2010Numerical analysis of entropy generation in concentric curved annular ducts
Kucuk, Haydar
The entropy generation has been numerically investigated in concentric curved annular square ducts under constant wall temperature boundary condition. The problem has been assumed to be steady, hydrodynamically and thermally fully developed and incompressible laminar flow with constant physical properties. The solutions of discretized equations for continuity, momentum and energy have been obtained by using an elliptic Fortran Program based on the SIMPLE algorithm. Solutions have been achieved for i) Dean numbers ranging from 3.6 to 207.1, ii) Annulus dimension ratios of 5.5, 3.8, 2.9 and 2.36, and iii) Prandtl number of 0.7. In this regard, local entropy generation as well as overall entropy generation in the whole flow field has been analyzed in detail. Moreover, the effects of Dean number and annulus dimension ratio on entropy generation arising from the friction and heat transfer have been investigated. Accordingly, it is concluded that the effect of volumetric entropy generation that is a result of fluid frictional irreversibility can be neglected as compared with volumetric entropy generation due to heat transfer irreversibility. As Dean number increases, the distribution of volumetric entropy generation coming out from the heat transfer irreversibility is formed by the temperature field, which is depending on the curvature.
- MakaleYalnız künye2010An analysis of the factors affecting birth weight and actual milk yield in swedish red cattle using regression tree analysis
Topal, M.; Aksakal, V.; Bayram, B.; Yaǧanoǧlu, M.
Performance records (birth weight and actual milk yield) on 206 Swedish Red cattle maintained at private organic diary cattle enterprise in Kelkit district of Gümüşhane province, in Turkey, were analyzed through regression tree method to determine the effects of some factors affecting birth weight and actual milk yield. The birth weight of calves averaged as 41.034±4.218 kg. Out of total calves born, twin born calves were 2.9%. Single born calves were heavier (41.185±3.840 kg) than twin born (36.000±10.545 kg). The results revealed that the most significant variable affecting birth weight was birth type, followed by birth season, sex and body condition score (BCS2) of the dam during birth. Lactation period and peak milk yield were important variables affecting the actual milk yield in the dairy herd under investigation.
- MakaleYalnız künye2010Finite element model updating of an arch type steel laboratory bridge model using semi-rigid connection
Altunişik, Ahmet Can; Bayraktar, Alemdar; Sevlm, Bariş; Kartal, Murat Emre; Adanur, Süleyman
This paper presents finite element analyses, experimental measurements and finite element model updating of an arch type steel laboratory bridge model using semi-rigid connections. The laboratory bridge model is a single span and fixed base structure with a length of 6.1 m and width of 1.1m. The height of the bridge column is 0.85 m and the maximum arch height is 0.95 m. Firstly, a finite element model of the bridge is created in SAP2000 program and analytical dynamic characteristics such as natural frequencies and mode shapes are determined. Then, experimental measurements using ambient vibration tests are performed and dynamic characteristics (natural frequencies, mode shapes and damping ratios) are obtained. Ambient vibration tests are performed under natural excitations such as wind and small impact effects. The Enhanced Frequency Domain Decomposition method in the frequency domain and the Stochastic Subspace Identification method in the time domain are used to extract the dynamic characteristics. Then the finite element model of the bridge is updated using linear elastic rotational springs in the supports and structural element connections to minimize the differences between analytically and experimentally estimated dynamic characteristics. At the end of the study, maximum differences in the natural frequencies are reduced on average from 47% to 2.6%. It is seen that there is a good agreement between analytical and experimental results after finite element model updating. Also, connection percentages of the all structural elements to joints are determined depending on the rotational spring stiffness.
- MakaleYalnız künye2010Optimum design of planar beams based on sensitivity analysis
Uysal, H.; Asci Demiröz, N.; Uzman, U.
In this study, the size optimization problem of a beam, in which the beam heights are determined along the beam axis, is considered as a shape optimization problem of a plate in plane elasticity. To achieve the shape optimization, different principles such as structural analysis, sensitivity analysis and mathematical programming are interrelated. The ANSYS that is a reliable finite element package programme is used only for the static analysis. The objective of this optimization problem is to minimize the volume of the beam under the constraints that the maximum value of the von Mises stress in each node do not exceed a predefined value and the beam axis is to remain straight. Design variables are the vertical coordinates of the corner nodal points of design elements. The design sensitivities are calculated through the finite, difference method and linear programming technique is used for obtaining the final shape of a beam. Several examples are solved under different loadings and boundary conditions. The obtained optimum beam volumes and the design variables are given in tables and the optimum beam shapes are plotted. One of the results given is compared with the literature.
- MakaleYalnız künye2010Insight into magma genesis at convergent plate margins a case study from the eastern Pontides (NE Turkey)
Kaygusuz, Abdullah; Siebel, Wolfgang; Ilbeyli, Nurdane; Arslan, Mehmet; Satir, Muharrem; Şen, Cüneyt
Convergent plate margins are the most intense areas of granitoid magmatism on Earth. The Eastern Pontide Magmatic Belt in NE Turkey represents a paleo-arc with numerous quartz diorite to syenite intrusions, ranging in age from 142 to 56 Ma and being composed of K-feldspar, plagioclase, quartz, pyroxene, hornblende, biotite, and Fe-Ti oxides. The granitoids exhibit low- to high-K calc-alkaline, metaluminous to slightly peraluminous I-type features and contain abundant mafic magmatic enclaves (MME). They are characteristically enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE) relative to high field strength elements (HFSE). Chondrite-normalized REE patterns are fractionated (LaN/LuN= 1.49-17.4) with pronounced negative Eu anomalies (Eu/Eu* = 0.46-1.77). Initial 87SrZ86Sr values are between 0.7056 and 0.7079, and εNd(1) values between -5.3 and 1.6. Fractional crystallization, magma mixing/mingling and crustal contamination played an important role during magma evolution. All these characteristics, combined with the low values of K2O/Na2O, Mg-number, ASI and ratios Of Al 2O3/ (FeOT+MgO+TiO2) and (Na 2O+K2O)/(FeOT+MgO+TiO2), suggest an origin by dehydration melting of mafic (amphibolitic) or tonalitic lower crustal source rocks.
- MakaleYalnız künye2010Assessment of medical home care needs in Turkish population
Sahinoz, Saime; Sahinoz, Turgut; Eker, Hasan Huseyin; Unlu, Suleyman Ersin
Objective: To determine the home healthcare needs of the elderly so as to develop proper home Healthcare Services. Methodology: This descriptive study was carried out in a county of Kocaeli province-Turkey. Data was collected through a specially designed questionnaire through face to face interview technique. The data were analyzed by the computer using the SPSS package program. Chi-square test was used for the statistical analysis. Results: This study showed that 14.6% of the population had at least one diagnosed disease. Among them, 1.8% was disabled, 4.1% was elderly and 1.1% of the households were in need of home care services. Conclusions: Home care needs were found to be low in this study. Its main cause was that elderly population was not aware of the availability of such a service in the country.