Gümüşhane ÜniversitesiGümüşhane ÜniversitesiAçık Erişim Arşivi · RDL Open

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  • MakaleYayıncıda açık erişim2026
    Measurement-aware zero-phase iterative learning control for robust regulation of nonideal boost converters in electric vehicle fast charging

    Altan, Aytaç; Alzaidi, Mohammed S.; Yanarateş, Cağfer

    Integrating battery energy storage with DC-DC boost converters for electric vehicle fast charging exposes the regulator to ageing-induced parameter drift, periodic load pulses, and, critically, the nonidealities in the output-voltage sensing chain. This paper proposes a measurement-aware, zero-phase iterative learning control scheme for robust output-voltage regulation of a nonideal boost converter whose parameters are matched to those of a commercial Texas Instruments TPS6102x battery regulator. The controller combines an inner proportional-integral stabilizing loop with an outer zero-phase learning law that updates a feedforward correction based on the sensor-captured output trajectory; a forward-backward robustness filter suppresses the amplification of measurement noise and quantization across successive trials without introducing phase lag. The averaged small-signal model is validated against a 960 kHz switched simulation, with agreement within 0.2% at the operating point and a transient-waveform correlation of 0.91, while the bandwidth limitations imposed by the lightly damped resonance and the nonminimum-phase dynamics on feedback are quantified from the loop frequency response. Because feedback alone is bandwidth-limited, the learning feedforward recovers the intrinsic converter speed for the repetitive task and reduces the periodic tracking error by more than an order of magnitude relative to a fairly tuned baseline. A bounded-error convergence theorem shows that, under real sensing, the tracking error converges to a neighbourhood whose size is proportional to the measurement-disturbance level; this is confirmed numerically, with the asymptotic error scaling approximately linearly with the noise standard deviation once the noise dominates the filter bias. Systematic sweeps of converter resolution, noise, and sensor delay show that the zero-phase measurement-aware law remains bounded where a naive learning law diverges, and a 500-sample Monte Carlo study confirms robustness to component tolerances, load variation, and parasitic aging. The primary physical task is the rejection of a repeating high-current charging pulse: over successive charging cycles the scheme reduces the periodic output-voltage sag from 35% to below 0.01%, whereas the best feedback comparator leaves a 17% residual, and the sinusoidal reference used elsewhere serves as a spectral diagnostic that isolates the feedback-bandwidth ceiling at a single known frequency. The learning law is further verified in closed loop on the cycle-by-cycle switched large-signal converter, where it converges and stays bounded. A per-unit scale-invariance analysis then establishes the conditions under which the design obtained on the low-power benchmark transfers to fast-charging power levels, as confirmed on a 400 V, 6.1 kW stage that reproduces the benchmark convergence exactly.

    • SDG 7 · Erişilebilir ve Temiz Enerji
    • SDG 9 · Sanayi, Yenilikçilik ve Altyapı
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  • MakaleYayıncıda açık erişim2026
    Blinking without eyelids: first video-documented evidence of a blink-like reflex in Ophisops elegans (Reptilia: Lacertidae)

    Çelebi, Turan Meriç; Çelikağı, Yusuf; Kınay, Tuana; Kuyucu, Arda Cem; Kurnaz, Muammer; Şahin, Mehmet Kürşat

    Eyelids play a crucial role in protecting the eyes of vertebrates; however, certain reptile species, such as Ophisops elegans, completely lack movable eyelids. In this study, we present the first video-documented evidence of a blink-like reflex in O. elegans, captured through endoscopic field observations and corroborated by laboratory video analysis. The observed movement consisted of a brief convex deformation of the ocular surface, lasting approximately 0.3 s and resembling a blink despite the presence of a fixed transparent brille. This behavior was observed once in the field and twice under controlled laboratory conditions. We propose that O. elegans may employ subtle contractions of the ocular musculature to mimic the protective function of blinking. These findings indicate a novel compensatory mechanism in eyelidless lizards and underscore the need for further research into ocular adaptations among reptiles.

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  • MakaleAçık Erişim2026
    Investigation of the enzyme-inhibitory, antibacterial, and anticancer properties of metal phthalocyanines

    Topal, Meryem; Topal, Fevzi; Yilmaz, Fırat; Bulut Atalay, Esra; Koçyiğit, Ümit Muhammet; Güzel, Emre

    In this study, the enzyme inhibitory, antibacterial, and anticancer activities of a phthalonitrile derivative and its metal phthalocyanines (Pcs; indium, zinc, copper, cobalt, and manganese; 1–6) were investigated. The cobalt and manganese Pcs were synthesized for the first time in this study. The inhibitory activities of the symmetric Pcs, which were expected to interact with acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) via their 4-(isopropylbenzyl)oxy substituents through host–guest interactions, were investigated. More selective inhibition of AChE than BChE was observed for these compounds. For AChE, CoPc was identified as the most potent inhibitor (IC50 = 14.81 nM), whereas for BChE, InPc was identified as the most potent inhibitor (IC50 = 56.35 nM). The Ki values indicated that most compounds exhibited competitive inhibition; copper phthalocyanine (CuPc) showed particularly strong inhibition against AChE (Ki = 3.08 nM ± 1.12), whereas the lowest Ki value against BChE was observed for MnPc (Ki = 25.98 ± 1.97 nM). Most compounds exhibited competitive inhibition; however, CuPc showed competitive inhibition toward AChE but a noncompetitive inhibition pattern toward BChE. Dual inhibition of AChE and BChE by these compounds may be promising for addressing cholinergic deficits associated with Alzheimer’s disease. In addition, the acceptability of compounds 1–6 with respect to pharmacological drug-likeness criteria was assessed based on predicted absorption, distribution, metabolism, excretion (ADME) outcomes. In antibacterial tests, varying levels of inhibition were observed against selected bacterial strains. In anticancer assays, all compounds exhibited high cytotoxicity against the MCF-7 breast cancer cell line. Higher antiproliferative activity was observed for CuPc than for the other compounds. Morphological changes were induced in cancer cells by CuPc and MnPc. Overall, these compounds may have potential as enzyme inhibitors and as antibacterial and anticancer agents.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
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  • MakaleAçık Erişim2023
    A study on the magnetite skarn mineralization (Gümüşhane, Türkiye): a magnetic survey

    Sipahi, Ferkan; Sadiklar, M. Burhan; Gücer, Mehmet Ali; Aydin, Ali; Kara, Rasim Taylan

    Iron (Fe)-skarn mineralizations (Çambaşı, Dereli, Eğrikar, Karadağ, Kopuz, Sekü, Donguldere, Arnastal, Özdil, Ögene, İkizdere, Ovit Dağı, Kartiba, etc.) in the eastern part of the Pontides (NE Türkiye) are accommodated in the Pontide paleomagmatic arc and the eastern part of the Pontides Metallogenic Belt containing numerous various deposits. Fe-skarn mineralization around the Arnastal Plateau (Gümüşhane-Türkiye) is fragmentary in this area, which is covered with plants (grasses, flowers, etc.). Thus, it was attempted to describe the subsurface structures and Fe mineralization using an interpretation of the available geological and existing magnetic data in this area. Granitoid and volcano-sedimentary series (Upper Cretaceous) outcrop in the study area. These volcanosedimentary series consist of limestone, sandy limestone, marl, andesite, quartz andesite, basalt, and their equivalent pyroclastics. They include a thin layer of the red limestone (Upper Cretaceous) and olistolith recrystallized limestones (Jurassic-Lower Cretaceous). Zigana granitoid, intruding into all of these rocks, is high-K calc-alkaline and metaluminous and is classified as quartz monzonite, monzogranite, granite, and syenogranite as a result of its modal composition. Contact pyrometasomatic mineralization occurs in between the limestone and granitoids in the Arnastal Plateau. In addition to petrographic and mineralogical studies, magnetic methods were applied to an area of approximately 10 km2 to find any covered Fe deposits. Magnetic susceptibility values measured on the outcropped rocks ranged from 1 to 34 (10–7 SI) for limestone, 78 to 3750 (10–7 SI) for basalt, and 105 to 3946 (10–7 SI) for granitoids. It is considered that these ranges express the alteration (physical or chemical) of the rocks, their homogeneity, and the lack or presence of Fe minerals. The magnetic survey was conducted along a study area measuring 12,075 m long with 25 and/or 50 m station spacing. Processing of the magnetic data revealed the presence of eight buried Fe ores that could represent either massive or disseminated mineralization between the Sarıtaş and Kurtdere plateaus. Magnetite ore bodies may be present from the surface to a depth of approximately 15–25 m inside the limestone. In addition to the identification of new magnetite ore mineralization or bodies, a new geological map was designed by determining probable formation boundaries with this magnetic survey.

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  • MakaleYayıncıda açık erişim2022
    Tectonic and structural characteristics of Erzurum and its surroundings (Eastern Turkey): a detailed comparison between different geophysical parameters

    Özer, Çağlar; Öztürk, Serkan; Pamuk, Eren

    The tectonic and structural properties of Erzurum and its surroundings have been investigated by evaluating the seismo-tectonic b-value, magnetic anomaly, edge detection analysis (total horizontal derivative (THDR) and tilt angle (TA)), Curie Point Depth (CPD), P-wave velocity (Vp), and Vp / Vs (S-wave velocity) ratio and by imaging the regional distributions of these parameters. For this purpose, all parameters have been combined to be able to reveal the new useful results on the study region and are presented for different locations and depths. The Vp values have been accompanied by high Vp / Vs ratios and shallow CPD values in the areas with geothermal regions such as Tekman, Söylemez, and the northern part of Karlıova. In the tectonically active regions such as Ilıca, Dumlu, Pasinler, Çat, Karlıova and Karaçoban, high reduction-to – the-pole (RTP) total magnetic anomaly was accompanied by low Vp values in harmony. Besides, the low Vp values between 0 and 10 km and high b-values can be related to the weakness zones and the areas in which earthquake hazards are high in the study area. The low Vp values in the 0 km horizontal slice are in accordance with the high RTP total magnetic anomaly values in the triangle area between Aşkale, Ilıca-Dumlu-Pasinler, Narman, and Karaçoban. Uniformly, high Vp and low RTP total magnetic anomaly inclusions overlap in Çat and Tekman. In some regions such as Dumlu, Narman, Horasan, Karaçoban and south of Karlıova, the tilt angle values are positive (positive values in the tilt angle map correspond to the center of the structure causing the magnetic anomaly) and the Vp values are low, but there is not a complete harmony between these parameters. These results show that variations on these parameters are related to each other, and these types of geophysical data are required for tectonic and structural features at different locations and depth levels.

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  • MakaleAçık Erişim2021
    Anatomy of october 30, 2020, samos (Sisam) –kuşadası earthquake (mw 6.92) and its influence on aegean earthquake hazard

    Bulut, Fatih; Doğru, Aslı; Yaltirak, Cenk; Yalvaç, Sefa; Elge, Murat

    We investigated rupture geometry, size, and slip distribution of October 30, 2020, Samos (Sisam)–Kuşadası earthquake combining seismographs, GPS measurements, and SAR analysis. Right after the earthquake, we measured 13 additional campaign-based GPS sites to intensify the available GPS network consisting of 10 continuous stations. We combined all available seismographs to have the best possible accuracy for mainshock and aftershock hypocenter locations. We compiled all available seismic profiles and integrated them using high-resolution bathymetry to map seismically active faults. The mainshock hypocenter is located at 37.913 ± 0.009 N° and 26.768 ± 0.017 E° and a depth of 12.3 ± 1.7 km. Our fault plane solution shows that the mainshock has almost a pure normal-type mechanism. Based on accurate aftershock locations as well as InSAR results, the mainshock rupture is subsegmented with two north-dipping rupture planes. The rupture probably starts on a low angle plane generating 1.1 m average slip between the depths of 9–14 km. It merges to a steep plane at 9 km depth where it generates 1.2 m average slip extending towards the surface near the shoreline of Samos (Sisam) Island. Total size of the two rupture planes and their average slips determine that the magnitude of the mainshock is (Mw ) 6.92 ± 0.02. The mainshock has substantially increased Coulomb stress on several fault segments near the towns Kuşadası and Söke, which have the potentials to generate strong earthquakes. It also nonnegligibly increased Coulomb stress on several fault segments south of İzmir giving a warning for increased earthquake hazard in this highly inhabited area.

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  • MakaleAçık Erişim2021
    Optimization of three-element tuned mass damper for single degree of freedom structures under ground acceleration; [Yer ivmesi etkisi altındaki tek serbestlik dereceli yapılar için üç elemanlı ayarlı kütle sönümleyicinin optimizasyonu]

    Araz, Onur

    Passive control devices have been used for a long time to reduce unwanted vibrations. The most commonly used of these devices are tuned mass dampers. The optimum parameters of the three-element tuned mass damper for damped main structures due to ground acceleration are investigated in this paper. Unlike the traditional tuned mass damper, the three-element tuned mass damper contains two spring elements and one of them is connected in series with the damping element. The optimum parameters are obtained by simulated annealing algorithm. Numerical results show that the three-element tuned mass damper is very effective in reducing dynamic vibrations of the damped structures.

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  • MakaleAçık Erişim2020
    Highly sensitive fluorometric method based on nitrogen-doped carbon dot clusters for tartrazine determination in cookies samples

    Gümrükçüoğlu, Abidin; Başoğlu, Aysel; Kolayli, Sevgi; Di̇Nç, Saliha; Kara, Meryem; Ocak, Miraç; Ocak, Ümmühan

    Nitrogen-doped carbon nanodots (CDs) were prepared via the solvothermal method, using urea and triethylene glycol as the starting materials. The as-prepared CDs had individual diameters of approximately 100 nm and were in clusters of different sizes. The surface composition and optical properties of the as-prepared CDs were characterized. They exhibited multicolor emission properties in the visible range when excited with a wide wavelength range. The aqueous solution of the CDs was used in highly sensitive tartrazine determination. The fluorescence quenching of the CDs was in a linear relationship with the concentrations of tartrazine in the range of 0.5–30.0 µM. The detection limit of the assay was 0.18 µM. Acceptable recovery results were obtained via spike-recovery experiments on cookie samples.

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  • MakaleAçık Erişim2020
    Excess lifetime cancer risk due to natural radioactivity in Gümüşhane Province, NE Turkey

    Maden, Nafiz; Akaryali, Enver; Gücer, Mehmet Ali

    In this study, 162 in situ measurements of 238U, 232Th, and 40K radionuclide concentrations dataset taken by the gamma-ray spectrometer in Gümüşhane, Turkey are presented. The gamma ray measurements were performed by a 512-channel, three-window gamma-ray spectrometry equipment made by GF Instruments. We first observed the radionuclides of the 238U,232Th, and 40K values in Gümüşhane. We then calculated the hazard indices of gamma radiation such as annual effective dose equivalent (AEDE), internal and external hazard index (Hin, Hex), and excess lifetime cancer risk (ELCR) based on the radionuclide abundances of 238U, 232Th, and 40K for the first time. In Gümüşhane, the average activity concentrations of radionuclides 238U, 232Th, and 40K were measured as 58.7 ± 34.3 Bq kg-1, 62.7 ± 37.2 Bq kg-1, and 1026.8 ± 486.0 Bq kg-1, respectively. The average outdoor annual effective dose equivalent and ELCR values were 132.2 ± 63.2 mSv yr-1 and 0.40 ± 0.19 × 10-3, respectively. Numerical results indicate that the radiological parameters (AEDE and ELCR) obtained for Gümüşhane Province were greater than the world’s mean values.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
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  • MakaleAçık Erişim2020
    Nature of clays in late cretaceous dacitic rocks in the eastern sakarya zone (Ne turkey): A geochemical and isotopic approach

    Sipahi, Ferkan; Gücer, Mehmet Ali; Sadiklar, Münür Burhan

    Late Cretaceous felsic rocks are common in the eastern Pontides (NE Turkey). These rocks developed as an island arc from the Jurassic to the Miocene; they also host numerous volcanogenic massive sulfide deposits. The Late Cretaceous dacites that outcrop around Zigana Mountain (Gümüşhane, NE Turkey) were exposed to intensive hydrothermal alteration. Widespread hydrothermal alteration of Late Cretaceous dacite in Zigana Mountain has led to the formation of well-developed clay minerals. Their main alteration products are sericite, chlorite, and carbonates (ankerite and calcite). The clay minerals identified by X-ray diffraction and differential thermal analysis include illite, chlorite, small amounts of kaolinite, and smectite. The polytype of illite is 2M1. Illites formed as a result of hydrothermal alteration of feldspars; they are also Fe-and Mg-poor. Chlorite is characterized by decreasing Fe/(Fe+ Mg) ratio with increasing alteration grade and has a trioctahedral structure. Chlorite geothermometer calculations (100–300°C) reflect the activities of hydrothermal solutions. Chlorite forms in more alkaline conditions compared with illite, as its formation is associated with the presence of carbonates. Oxygen and hydrogen stable isotope values, K-Ar dating of illites, and textural and chemical evidence suggest that clays might have formed mainly by alteration of minerals in dacitic rocks with hydrothermal fluids of magmatic origin during the Campanian under acidic–weak alkaline conditions.

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  • MakaleAçık Erişim2020
    Assessment of acid mine drainage formation using geochemical and static tests in mutki (Bitlis, se Turkey) mineralization area

    Gücer, Mehmet Ali; Alemdağ, Selçuk; Akaryali, Enver

    In this study, geochemical analyses, as well as short-term contact leaching and acid-base accounting tests, were carried out to determine the occurrence of acid mine drainage (AMD) by static tests in the ore stockpile areas at the Mutki Cu-Fe-Cr deposit (Bitlis, SE Turkey). According to the short-term contact leaching tests, the high enrichment in trace element concentrations in ore-bearing samples, especially in potentially toxic metals such as Cr, Cu, Mn, and Zn, were directly related to sulphide and oxide mineralizations. The pH (3.27–4.05) values of water samples, together with the classification of the intracontinental water resources, indicated that the water quality is the fourth class. Leaching tests, paste pH (3.42–4.46) and sulphide-sulphur (3.9–13.4 wt%) values also suggested that there was AMD production potential in the mineralization area. The AMD production potential was supported by the high mobility of several elements, such as Fe, Mg, Cr, As, Cu, S, and Zn. In ore samples, net neutralization potential (NNP) and net potential ratio (NPR) values were less than –20 kg CaCO3 /t and 1, respectively. The basalts forming the basement rock of the stockpile area were characterized by permeable to slightly permeable properties that potentially increase the contamination risk of the groundwater due to seepage in the stockpile area. In order to prevent seepage in the stock area, geomembrane (synthetic waterproofing covers) should be laid at the base to ensure impermeability. The improvements planned in the stock area were modeled by the finite element method and seepage discharges at a depth of 5 m were determined as 1.34 × 10–17m3/s. Thanks to these planned applications, surface and groundwater pollution can be efficiently prevented.

    • SDG 6 · Temiz Su ve Sanitasyon
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  • MakaleAçık Erişim2018
    The investigation of the lattice strains and crystallite sizes of Y358 and Y123 high-temperature superconductors

    Duzgun, Ibrahim

    In this study, the Y358 phase, the newest high-temperature superconductor member of the yttrium barium copper oxide family, was produced using the solid-state reaction technique. The Y358 superconductor exhibited the Meissner effect at low temperature (77 K). The X-ray diffraction spectra indicated that the crystal structure was almost identical to that of Y123, but with some impurity peaks. An X-ray peak broadening analysis was applied to determine the lattice strain, and the medial crystallite size was calculated perpendicular to the surface of the superconductor specimens. As a result of the analyses, it was determined that the crystallite size of the Y358 superconductor was about 1.125 times larger than that of the Y123 superconductor.

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  • MakaleAçık Erişim2018
    A rapid and sensitive spectrofluorometric method for the determination of au(III) based on fluorescence quenching of a 1,3,5-triphenyl-2-pyrazoline

    Başoğlu, Aysel; Ocak, Ümmühan; Fandakli, Seda; Yayli, Nurettin

    A simple, rapid, sensitive, and low-cost spectrofluorometric method was developed for the determination of Au(III) using 5-(2,3-dimethoxyphenyl)-3-(4-methoxyphenyl)-1-phenyl-4,5-dihydro-1H-pyrazole (L) in ethanol/water. The method is based on the change in the fluorescence intensity at 464 nm after excitation at 355 nm as a result of the reaction between the ligand and Au(III). The fluorescent emission of ligand at 464 nm decreased with the increasing of Au(III) concentration. The ligand concentration, pH effect, response time, and effect of foreign ions were determined. From the results of fluorescence titration experiments, it was found that the ligand (1 × 10−7 M) was selective and sensitive to Au(III) in EtOH-H2 O (1:1, v/v, phthalate buffer, pH 4.0). The calibration curve showed good linearity in the concentration range of 17.4–237.6 µg L−1 Au(III). The limits of detection and quantification were 5.2 and 17.4 µg L−1 Au(III) with a response time of 1 min, respectively. Satisfactory accuracy was obtained for standard reference material (CRM-SA-C Sandy Soil C). The proposed method was successfully applied to the determination of Au(III) in tap water, sea water, and stream water samples, and high levels of recovery were obtained.

    • SDG 6 · Temiz Su ve Sanitasyon
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  • MakaleAçık Erişim2018
    Single production of the excited muons at the SPPC-based ultimate μp collider

    Cąliskan, Abdullatif

    Single production potential of the excited muons at the SPPC-based ultimate muon-proton collider with center-of-mass energy of 116.6 TeV was analyzed. We calculated the production cross-sections and the decay widths of the excited muons with the process of μp → μX → γμX. We obtained the normalized transverse momentum and pseudorapidity distributions of the final-state particles to attain the kinematical cuts for the discovery of the excited muons. With these cuts, we determined the mass limits. It was shown that the discovery limits on the mass of the excited muons are 19.6 and 10.1 TeV for λ = mμ and λ=50 TeV, respectively.

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  • MakaleAçık Erişim2018
    Radii of uniform convexity of some special functions

    Aktaş, Ibrahim; Toklu, Evrim; Orhan, Halit

    In this investigation our main aim is to determine the radii of uniform convexity of selected normalized q -Bessel and Wright functions. Here we consider six different normalized forms of q -Bessel functions and we apply three different kinds of the normalization of the Wright function. We also show that the obtained radii are the smallest positive roots of some functional equations.

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  • MakaleAçık Erişim2018
    Bounds for radii of starlikeness and convexity of some special functions

    Aktaş, Ibrahim; Baricz, Árpád; Orhan, Halit

    In this paper we consider some normalized Bessel, Struve, and Lommel functions of the first kind and, by using the Euler-Rayleigh inequalities for the first positive zeros of a combination of special functions, we obtain tight lower and upper bounds for the radii of starlikeness of these functions. By considering two different normalizations of Bessel and Struve functions we give some inequalities for the radii of convexity of the same functions. On the other hand, we show that the radii of univalence of some normalized Struve and Lommel functions are exactly the radii of starlikeness of the same functions. In addition, by using some ideas of Ismail and Muldoon we present some new lower and upper bounds for the zeros of derivatives of some normalized Struve and Lommel functions. The Laguerre-Pólya class of real entire functions plays an important role in our study.

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  • MakaleAçık Erişim2017
    The effect of sintering in different atmospheres on superconductivity parameters of YBCO

    Başoǧlu, Mehmet

    YBa2Cu3O7 (Y123) is a superconductor material discovered in 1987 and its transition temperature is above the liquid nitrogen temperature. It is known that superconductor samples produced by the solid-state reaction route are very often sintered in air atmosphere. However, in the presented work, Y123 was prepared by the same technique using a sintering ambient composed of a mixture of oxygen and argon gases for the first time. Critical current densities of the samples were calculated using results of magnetization measurements. It was obtained from magnetization analysis that all the samples exhibited superconductor character. It was also observed that the sample sintered in the 50% oxygen and 50% argon atmosphere showed the highest critical current density.

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  • MakaleAçık Erişim2016
    Separation and preconcentration of Pb(II) and Cu(II) ions via carrier element-free coprecipitation using an acetohydrazide derivative

    Tümay, Süreyya Oǧuz; Yazar, Murat; Ozdeş, Duygü; Bektaş, Hakan; Duran, Celal

    A new method based on the combination of carrier element-free coprecipitation and flame atomic absorption spectrometric determination has been investigated for simultaneous separation and preconcentration of Pb(II) and Cu(II) ions in some environmental solid and liquid samples. The 2-f3-(4-methylbenzyl)-4-[2-(1H-indol-3-yl)ethyl]-5-oxo-4,5-dihydro-1H-1,2,4-triazol-1-ylg -N'-(phenylmethylene) acetohydrazide (MITA) was utilized as an organic coprecipitating agent without using a carrier element for coprecipitation of the analyte ions. The effects of experimental conditions including aqueous solution pH, MITA quantity, sample volume, standing time, and centrifugation rate and time were investigated in detail and optimized. The influences of some foreign ions were also evaluated on the quantitative recoveries of the analyte ions. The preconcentration factors were 125 for both analyte ions. The detection limits were 1.32 μgL-1 and 0.47 μg L-1 for Pb(II) and Cu(II) ions, respectively, and the relative standard deviations (RSDs) were lower than 4% for both analyte ions. After the accuracy of the method was checked, it was applied to sea and stream water as liquid samples and waste tea and tobacco as solid samples to determine the levels of Pb(II) and Cu(II) ions.

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  • MakaleYayıncıda açık erişim2016
    Organic geochemistry and element distribution in coals formed in eocene lagoon facies from the Eastern Black Sea Region,NE Turkey

    Saydam Eker, Çiğdem; Akpinar, İbrahim; Sipahi, Ferkan

    The amount and type,the inorganic element content,and the maturity of organic materials of Eocene coals,shaly coals,and coaly shales exposed in the Gümüşhane and Bayburt districts of the Eastern Black Sea Region of Turkey were investigated. The depositional environments and hydrocarbon potentials were also interpreted. The total organic carbon concentrations in the studied samples ranged from 0.50% to 63.08%. The samples from Özyurt,Kayadibi,and Tarhanas contained types II and III kerogen,and those from Sökmen and Manas contained type III kerogen. The samples contained Co,Cs,Ga,Hf,Th,U,Y,Mo,Be,Cd,Sb,and La,with average values similar to those of standard brown coals. The samples showed average contents of Co,Ga,Nb,Rb,V,Y,Cu,Pb,Zn,As,Be,and Se,similar to those of other Turkish coals. The sediment source of Eocene samples in the five areas was characterized by rocks with intermediate or mafic geochemical characteristics. The terrigenous/aquatic ratio of coal and shaly coal samples of the areas in question is >1. The sterane distribution was C29 > C28 > C27 and C29 > C27 > C28 for the Özyurt and Tarhanas areas,respectively. The average Tmax values for samples are between 424 °C and 460 °C. For samples Oz-1 and Ta-2,22S/(22S + 22R) homohopane (C32) ratios are 0.48 and 0.61,respectively; 20S/(20S + 20R) sterane (C29) ratios are 0.18 and 0.53,respectively; and Ts/(Ts + Tm) ratios are 0.015 and 0.64,respectively. The Pr/Ph ratios of the samples are >3. The studied samples have low sterane/hopane and high (C19+C20)/C23) ratios without anoxic biomarkers (17α(H)-28,30-bisnorhopane). Based on these data,the coals,shaly coals,and coaly shales were probably deposited under an oxic-suboxic mixture of marine and terrestrial environment conditions; these materials contain terrestrial organic matter and cannot generate hydrocarbon.

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  • MakaleAçık Erişim2015
    Synthesis and biological evaluation of a new series of 4-alkoxy-2-arylquinoline derivatives as potential antituberculosis agents

    Tosun, Gonca; Arslan, Tayfun; Iskefiyeli, Zeynep; Küçük, Murat; Karaoʇlu, Şengül Alpay; Yayli, Nurettin

    Three new series of 33 quinolone compounds, 2-(2-, 3-, and 4-fluorophenyl)-4-O-alkyl(C5-15)quinolines (7a-k, 8a-k, and 9a-k), were synthesized from 2-(2-, 3-, and 4-fluorophenyl)-2,3-dihydroquinolin-4(1H )-one (4, 5, and 6) by the reaction of alkyl halides under basic conditions in DMF. The new compounds 7a-k, 8a-k, and 9a-k were synthesized from flavonones 4-6, which can be considered new precursors for quinoline synthesis through a one-step reaction. All the target compounds (7a-k, 8a-k, and 9a-k) were evaluated for their in vitro antimicrobial activity against nine test microorganisms. They showed the most activity against Mycobacterium smegmatis with minimum inhibitory concentrations (MIC) of 62.5-500 μg/mL, indicating their potential uses as antituberculosis agents. Among them 8a-k (m-fluoride) were the most active compounds against M. smegmatis (MIC, 62.5-125 μg/mL). The newly synthesized title compounds were also evaluated for their in vitro antioxidant activities using DPPH• radical scavenging and FRAP tests. They showed at a low concentration (mg/mL) a range of SC50 values of 0.03-12.48 mg/mL (DPPH•) and 0-722 μM (FRAP), respectively. The antioxidant results of compounds 7a-k, 8a-k, and 9a-k revealed that the length of the alkyl chain was negatively correlated with antioxidant capacity.

    • SDG 3 · Sağlık ve Kaliteli Yaşam
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