Gümüşhane ÜniversitesiGümüşhane ÜniversitesiAçık Erişim Arşivi · RDL Open

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  • MakaleYayıncıda açık erişim2016
    Modeling deformation modulus of a stratified sedimentary rock mass using neural network, fuzzy inference and genetic programming

    Alemdag, S.; Gurocak, Z.; Cevik, A.; Cabalar, A.F.; Gokceoglu, C.

    This paper investigates a series of experimental results and numerical simulations employed to estimate the deformation modulus of a stratified rock mass. The deformation modulus of rock mass has a significant importance for some applications in engineering geology and geotechnical projects including foundation, slope, and tunnel designs. Deformation modulus of a rock mass can be determined using large scale in-situ tests. This large scale sophisticated in-situ testing equipments are sometimes difficult to install, plus time consuming to be employed in the field. Therefore, this study aims to estimate indirectly the deformation modulus values via empirical methods such as the neural network, neuro fuzzy and genetic programming approaches. A series of analyses have been developed for correlating various relationships between the deformation modulus of rock mass, rock mass rating, rock quality designation, uniaxial compressive strength, and elasticity modulus of intact rock parameters. The performance capacities of proposed models are assessed and found as quite satisfactory. At the completion of a comparative study on the accuracy of models, in the results, it is seen that overall genetic programming models yielded more precise results than neural network and neuro fuzzy models.

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  • MakaleYalnız künye2016
    Application of response surface methodology for optimizing the recovery of phenolic compounds from hazelnut skin using different extraction methods

    Odabaş, Halil İbrahim; Koca, Ilkay

    Hazelnut skin which is a rich source of phenolic compounds is a by-product of hazelnut roasting process. In present study, ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE) and supercritical carbon dioxide extraction (SCE) methods were applied for recovery of phenolic compounds from hazelnut skin. Response surface methodology was used to estimate optimum extraction conditions. Extraction studies were performed according to Box-Behnken Design. Temperature (UAE)/power (MAE), time and ethanol concentration were independent variables for UAE and MAE. The independent variables selected for SCE were temperature, time and pressure. The optimum extraction conditions were 45 min and 67.2–67.6% ethanol concentration, 600 W, 6 min and 55.03–56.23% ethanol concentration and 42.72–49.10 °C, 59.83–60.00 min and 10.01–11.48 bar, for UAE, MAE and SCE respectively. Total phenolic content, FRAP and 1/EC50 values at the optimum conditions were 122.99–123.01 mg GAE/g, 612.20–613.25 mmol Fe(II)/g and 4.36 mL/mg for UAE, 111.53–111.55 mg GAE/g, 582.44–582.52 mmol Fe(II)/g and 2.48 mL/mg for MAE and 69.59–72.64 mg GAE/g, 426.25–465.52 mmol Fe(II)/g and 2.18–2.27 mL/mg for SCE, respectively. Maceration was performed for comparison with novel methods. UAE was found to be the best method of the extraction of phenolic compounds from hazelnut skin with the highest total phenolic content and antioxidant activity values.

    • SDG 12 · Sorumlu Üretim ve Tüketim
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  • MakaleAçık Erişim2016
    Geochronology and geochemistry of Eocene-aged volcanic rocks around the Bafra (Samsun, N Turkey) area: Constraints for the interaction of lithospheric mantle and crustal melts

    Temizel, Irfan; Arslan, Mehmet; Yücel, Cem; Abdioğlu, Emel; Ruffet, Gilles

    40Ar-39Ar age, whole-rock chemical, and Sr-Nd isotope data are presented for the post-collisional, Eocene (51.3-44.1 Ma)-aged volcanic rocks from the Bafra (Samsun) area in the western part of the Eastern Pontides (N Turkey) aiming to unravel their sources and evolutionary history. The studied Eocene volcanic rocks can be divided into two groups: analcime-bearing (tephritic lava flows and dykes) and analcime-free (basaltic to trachytic lava flows and basaltic dykes). The analcime-bearing volcanic rocks have a fine-grained porphyritic texture with clinopyroxene phenocrysts, whereas analcime-free volcanic rocks show a variety of textures including hyalo-microlitic microgranular porphyritic, intersertal, trachytic, fluidal, and glomeroporphyritic. The volcanic rocks also show evidence of mineral-melt disequilibrium textures such as sieved, rounded, and corroded plagioclases, partially melted and dissolved clinopyroxenes and poikilitic texture. Petrochemically, the parental magmas of the volcanic rocks evolved from alkaline to calc-alkaline lava suites and include high-K and shoshonitic compositions. They display enrichments in light rare earth and large ion lithophile elements such as Sr, K, and Rb, as well as depletions in high field strength elements such as Nb, Ta, Zr, and Ti, resembling subduction-related magmas. The analcime-bearing and -free volcanic rocks share similar incompatible element ratios and chondrite-normalised rare rearth element patterns, indicating that they originated from similar sources. They also have relatively low to moderate initial 87Sr/86Sr (0.7042-0.7051), high positive εNd(t) values (+0.20 to +3.32), and depleted mantle Nd model ages (TDM1 = 0.63-0.93 Ga, TDM2 = 0.58-0.84 Ga). The bulk-rock chemical and Sr-Nd isotope features as well as the high Rb/Y and Th/Zr, but low Nb/Zr and Nb/Y ratios, indicate that the volcanic rocks were derived from a lithospheric mantle source that had been metasomatised by slab-derived fluids. Trace element modelling suggests that the parental magma(s) of the volcanic rocks represent mixtures of melts derived by low-degree (~5-10%) partial melting of spinel-lherzolite (40-85%) and garnet-lherzolite (15-60%) mantle sources. Sr-Nd isotopic modelling also suggests that a 25-35% lower crustal component was added in the parental magmas; AFC modelling additionally indicates minor upper crustal contamination during the evolution of the volcanic rocks. In conclusion, integration of the geochemical, petrologic, and isotopic data with regional geology suggests that the analcime-bearing and -free volcanic rocks evolved from parental magma(s) derived from melts of a subcontinental lithospheric mantle and lower crustal sources.

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  • MakaleYalnız künye2015
    A review for genesis of continental arc magmas: U, Th, K and radiogenic heat production data from the Gümüşhane Pluton in the Eastern Pontides (NE Türkiye)

    Maden, Nafiz; Akaryali, Enver

    In this study, in situ radioelemental (238U, 232Th and 40K) measurements and heat production rate evaluation have been conducted at 132 sites in the Gümüşhane Pluton of the Eastern Pontides Orogenic Belt (EPOG) of Northern Türkiye. The average K, U and Th values for granites are 4.35±0.71%, 5.85±2.74ppm, 22.13±5.55ppm, respectively; microgranites 4.33±1.37%, 7.12±2.23ppm, 24.11±9.59ppm; metagranite 3.93±0.68%, 6.24±2.75ppm, 12.87±3.92ppm; andesite/basalt 1.75±0.74%, 3.22±1.07ppm, 9.01±5.14ppm. Based on the abundances of K, U and Th, the radiogenic heat production (RHP) values, which is a reflection of the geological rock types, are estimated as 3.52±1.03μWm-3, 3.86±1.31μWm-3, 2.93±0.89μWm-3, and 1.68±0.63μWm-3 for granites, microgranites, metagranites and andesite/basalt, respectively. The average heat production value for the study area is estimated as 2.83±1.39μWm-3, which is closer to the upper continental crustal value; contrary to the highest heat production value of granitic basement and the lowest heat production values of the sedimentary rocks. The study region is depicted with very high level of Th/U value ranging from 0.11 to 23.19 with mean value of 3.53 ± 2.5, which is comparatively close to the upper continental crustal estimate of 3.8. The numerical results verify that mantle-derived magmas are subjected to contamination with both middle and lower crustal material constituted by fragments of southerly dipping subduction of Tethys Ocean during the late Mesozoic-Cenozoic.

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  • MakaleYalnız künye2014
    Effect of different surface oxidation treatments on structural, mechanical and tribological properties of ultrafine-grained titanium

    Çelik, Ilhan; Alsaran, Akgün; Purcek, Gencaga

    Four different surface oxidation treatments, so-called, anodizing oxidation (AO), micro-arc oxidation (MAO), plasma oxidation (PO) and thermal oxidation (TO), were applied to ultrafine-grained (UFG) pure titanium produced by equal-channel angular extrusion/pressing (ECAE/P). Before and after all treatments, mechanical, structural and tribological properties were investigated. The strength of pure titanium increased substantially after ECAE process. TiO2 phases included the anatase and/or the rutile formed on the surface of UFG Ti depending on oxidation treatments. High strength of UFG Ti was deteriorated by TO and PO treatments because of the recrystallization occurred at high-temperature, while applications of MAO and AO did not cause a significant decrease in its strength due to the prevention of recrystallization of UFG Ti. All oxidation treatments brought about a remarkable increase in wear resistance of UFG Ti because of the formation of adhered and hard TiO2 film developed on the surface. It was concluded that the AO and MAO treatments could be applied to the UFG Ti without any deteriorations in bulk mechanical and wear properties to obtain biocompatible pure titanium with high strength and excellent wear resistance.

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  • MakaleAçık Erişim2013
    Geothermal structure of the eastern Black Sea basin and the eastern Pontides orogenic belt: Implications for subduction polarity of Tethys oceanic lithosphere

    Maden, Nafiz

    The numerical results of thermal modeling studies indicate that the lithosphere is cold and strong beneath the Black Sea basin. The thermal lithospheric thickness increases southward from the eastern Pontides orogenic belt (49.4 km) to Black Sea basin (152.2 km). The Moho temperature increases from 367 C in the trench to 978 C in the arc region. The heat flow values for the Moho surface change between 16.4 mW m-2 in the Black Sea basin and 56.9 mW m-2 in the eastern Pontides orogenic belt. Along the southern Black Sea coast, the trench region has a relatively low geothermal potential with respect to the arc and back-arc region. The numerical studies support the existence of southward subduction beneath the Pontides during the late Mesozoic-Cenozoic.

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  • MakaleAçık Erişim2013
    The genesis of the slab window-related Arzular low-sulfidation epithermal gold mineralization (eastern Pontides, NE Turkey)

    Akaryali, Enver; Tüysüz, Necati

    The Arzular mineralization is one of the best examples of epithermal gold deposits in the eastern Pontides orogenic belt. The mineralization is hosted by the subduction-related basaltic andesites and is mainly controlled by E-W and NE-SW trending fracture zones. The main ore minerals are galena, sphalerite, pyrite, chalcopyrite, tetrahedrite and gold. Homogenization temperatures of fluid inclusions are between 130 and 295 C for quartz and between 90 and 133 C for sphalerite. Sulphur isotope values obtained from pyrite, galena and sphalerite vary between -1.2‰ and 3‰, indicating that sulphur belongs to magmatic origin and was derived from the Lutetian non-adakitic granitic intrusions in the region. Oxygen isotope values are between 15.0‰ and 16.7‰, and hydrogen isotope values are between -87‰ and -91‰. The sulphur isotope thermometer yielded temperatures in the range of 244-291 C for the ore formation. Our results support the hypothesis that the Arzular mineralization is a low-sulfidation epithermal gold deposit associated with non-adakitic subduction-related granitic magmas that were generated by slab window-related processes in a south-dipping subduction zone during the Lutetian.

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  • MakaleAçık Erişim2013
    Petrogenesis of the late Cretaceous Turnagöl intrusion in the eastern Pontides: Implications for magma genesis in the arc setting

    Kaygusuz, Abdullah; Sipahi, Ferkan; Ilbeyli, Nurdane; Arslan, Mehmet; Chen, Bin; Aydinçakir, Emre

    A series of Cretaceous plutons is present in the eastern Pontides of northeastern Turkey. The Turnagöl intrusion is the least studied and, thus, the least understood plutons in the orogen. This intrusion consists of hornblende-biotite granodiorites emplaced at 78 Ma based on LA-ICP-MS U-Pb zircon dating. It is of sub-alkaline affinity, belongs to the medium- to high-K calc-alkaline series, and displays features typical of I-type granites. The rocks of the intrusion are enriched in large-ion lithophile elements and light rare earth-elements with negative Eu anomalies (Eu/Eu* = 0.69-0.82), but are deficient in high-field-strength elements. They have a small range of ( 87Sr/86Sr)i (0.7060-0.7063), ÉNdi(-2.6 to -3.1), and δ18O (+8.1 to +9.1) values. Their Pb isotopic ratios are 206Pb/204Pb = 18.63-18.65, 207Pb/ 204Pb = 15.62-15.63, and 208Pb/204Pb = 38.53-38.55. The fractionation of plagioclase, hornblende, and Fe-Ti oxides had key functions in the evolution of the Turnagöl intrusion. The crystallization temperatures of the melts ranged from 758 to 885 C as determined by zircon and apatite saturation thermometry. All these characteristics, combined with the low values of K2O/Na2O and (Na 2O + K2O)/(FeOt + MgO + TiO2), as well as the high values of (CaO + FeOt + MgO + TiO2), suggest an origin by dehydration melting from a metabasaltic lower crustal source.

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  • MakaleAçık Erişim2013
    The nature of transition from adakitic to non-adakitic magmatism in a slab window setting: A synthesis from the eastern Pontides, NE Turkey

    Eyuboglu, Yener; Santosh, M.; Dudas, Francis O.; Akaryali, Enver; Chung, Sun-Lin; Akdaǧ, Kemal; Bektaş, Osman

    The eastern Pontides orogenic belt provides a window into continental arc magmatism in the Alpine-Himalayan belt. The late Mesozoic-Cenozoic geodynamic evolution of this belt remains controversial. Here we focus on the nature of the transition from the adakitic to non-adakitic magmatism in the Kale area of Gumushane region in NE Turkey where this transition is best preserved. The adakitic lithologies comprise porphyries and hyaloclastites. The porphyries are represented by biotite-rich andesites, hornblende-rich andesite and dacite. The hayaloclastites represent the final stage of adakitic activity and they were generated by eruption/intrusion of adakitic andesitic magma into soft carbonate mud. The non-adakitic lithologies include basaltic-andesitic volcanic and associated pyroclastic rocks. Both rock groups are cutting by basaltic dikes representing the final stage of the Cenozoic magmatism in the study area. We report zircon U-Pb ages of 48.71 ± 0.74 Ma for the adakitic rocks, and 44.68 ± 0.84 Ma for the non-adakitic type, suggesting that there is no significant time gap during the transition from adakitic to non-adakitic magmatism. We evaluate the origin, magma processes and tectonic setting of the magmatism in the southern part of the eastern Pontides orogenic belt. Our results have important bearing on the late Mesozoic-Cenozoic geodynamic evolution of the eastern Mediterranean region.

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  • MakaleYalnız künye2012
    The modified algorithm for the differential transform method to solution of Genesio systems

    Gökdoĝan, Ahmet; Merdan, Mehmet; Yildirim, Ahmet

    In this article, approximate analytical solution of chaotic Genesio system is acquired by the modified differential transform method (MDTM). The differential transform method (DTM) is mentioned in summary. MDTM can be obtained from DTM applied to Laplace, inverse Laplace transform and Padé approximant. The MDTM is used to increase the accuracy and accelerate the convergence rate of truncated series solution getting by the DTM. Results are given with tables and figures.

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  • MakaleYalnız künye2012
    A multistage differential transformation method for approximate solution of Hantavirus infection model

    Gökdoĝan, Ahmet; Merdan, Mehmet; Yildirim, Ahmet

    The goal of this study is presented a reliable algorithm based on the standard differential transformation method (DTM), which is called the multi-stage differential transformation method (MsDTM) for solving Hantavirus infection model. The results obtanied by using MsDTM are compared to those obtained by using the Runge-Kutta method (R-K-method). The proposed technique is a hopeful tool to solving for a long time intervals in this kind of systems.

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  • MakaleAçık Erişim2011
    Arc magmatism as a window to plate kinematics and subduction polarity: Example from the eastern Pontides belt, NE Turkey

    Eyuboglu, Yener; Santosh, M.; Bektas, Osman; Ayhan, Seda

    The Eastern Pontides orogenic belt in the Black Sea region of Turkey offers a critical window to plate kinematics and subduction polarity during the closure of the Paleotethys. Here we provide a brief synthesis on recent information from this belt. We infer a southward subduction for the origin of the Eastern Pontides orogenic belt and its associated late Mesozoic-Cenozoic magmatism based on clear spatial and temporal variations in Late Cretaceous and Cenozoic arc magmatism, together with the existence of a prominent south-dipping reverse fault system along the entire southern coast of the Black Sea. Our model is at variance with some recent proposals favoring a northward subduction polarity, and illustrates the importance of arc magmatism in evaluating the geodynamic milieu associated with convergent margin processes.

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  • MakaleYalnız künye2011
    Cultivar characterization of Aegean olive oils with respect to their volatile compounds

    Ilyasoglu, Huri; Ozcelik, Beraat; Hoed, Vera Van; Verhe, Roland

    Cultivar characterization of Aegean olive oils (cv. Ayvalik and Memecik) based on their volatile compounds was carried out. The main volatile compounds detected in the Aegean olive oils were the C6 compounds derived from polyunsaturated fatty acids through the lipoxygenase pathway. The C6 aldehydes and C6 alcohols contributing to the green and fruity sensory notes of olive oil were determined in the Aegean olive oils as the major volatile compounds. Significant differences in the levels of hexanal, (E)-2-hexenal, 3-ethyl-1,5-octadiene and total compounds from linolenic acid were observed between Ayvalik and Memecik oils (p < 0.01). Principal component analysis (PCA) and linear discriminant analysis (LDA) were applied to process the experimental data. The results of the chemometric analysis revealed that the two cultivars were clearly discriminated on the PC1-PC3 planes and LDA produced a 100% correct group classification.

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  • Dergi
    Scientia Horticulturae
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  • Dergi
    Communications in Nonlinear Science and Numerical Simulation
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  • Dergi
    Journal of Microbiological Methods
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  • Dergi
    Saudi Pharmaceutical Journal
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  • Dergi
    Results in Physics
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  • Dergi
    Microelectronic Engineering
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  • Dergi
    Surfaces and Interfaces
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