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Active control of a small-scalewind turbine blade containing magnetorheological fluid
(MDPI AG, 2018) Bolat F.C.; Sivrioglu S.
This research study proposes a new active control structure to suppress vibrations of a small-scale wind turbine blade filled with magnetorheological (MR) fluid and actuated by an electromagnet. The aluminum blade structure is manufactured using the SH3055 (BergeyWindpower Co. Inc., Norman, OK, USA) code numbered airfoil which is designed for use on small wind turbines. A dynamic interaction model between the MR fluid and the electromagnetic actuator is constructed to obtain a force relation. A detailed characterization study is presented for the proposed actuator to understand the nonlinear behavior of the electromagnetic force. A norm based multi-objective H2/H? controller is designed using the model of the elastic blade element. The H2/H? controller is experimentally implemented under the impact and steady state aerodynamic load conditions. The results of experiments show that the MR fluid- electromagnetic actuator is effective for suppressing vibrations of the blade structure. © 2018 by the authors.
Determination of structural, spectrometric and nonlinear optical features of 2-(4-hydroxyphenylazo)benzoic acid by experimental techniques and quantum chemical calculations
(2013) Cinar M.; Yildiz N.; Karabacak M.; Kurt M.
The optimized geometrical structure, vibrational and electronic transitions, chemical shifts and nonlinear optical properties of 2-(4-hydroxyphenylazo)benzoic acid (HABA) compound were presented in this study. The ground state geometrical structure and vibrational wavenumbers were carried out by using density functional (DFT/B3LYP) method with 6-311++G(d,p) basis set. The vibrational spectra of title compound were recorded in solid state with FT-IR and FT-Raman spectrometry in the range of 4000-400 cm -1 and 4000-10 cm -1 ; respectively. The fundamental assignments were done on the basis of the recorded spectra and total energy distribution (TED) of the vibrational modes. The 1 H and 13 C NMR spectra were recorded in deuterated DMSO solution, and gauge-invariant atomic orbitals (GIAOs) method was used to predict the isotropic chemical shifts. The UV-Vis absorption spectra of the compound were observed in the range of 200-800 nm in ethanol, methanol and water solvents. To investigate the nonlinear optical properties, the polarizability, anisotropy of polarizability and molecular first hyperpolarizability were computed. A detailed description of spectroscopic behaviors of compound was given based on the comparison of experimental measurements and theoretical computations. © 2012 Elsevier B.V. All rights reserved.
Asymmetric Friedel-Crafts alkylation of pyrrole with nitroalkenes catalyzed by a copper complex of a bisphenol A-derived Schiff base
(Elsevier Ltd, 2015) Özdemir H.S.; Şahin E.; Çakici M.; Kiliç H.
The asymmetric Friedel-Crafts (FC) alkylation of pyrrole with nitroalkenes was mediated by CuBr2 and a novel bisphenol A-derived chiral catalyst at room temperature. The catalyst was found to be applicable for the asymmetric FC alkylation of pyrrole with a wide range of nitroalkenes, affording optically active alkylated pyrroles with enantioselectivities up to 94%. Furthermore, enantiomerically pure 3-nitro-2-arylpropanamides were prepared by the oxidative cleavage of the pyrrole rings in the FC products with NaIO4/RuCl3 to demonstrate the synthetic application of the products. © 2015 Elsevier Ltd. All rights reserved.
In vitro inhibitory effects of palonosetron hydrochloride, bevacizumab and cyclophosphamide on purified paraoxonase-I (hPON1) from human serum
(Elsevier B.V., 2016) Türkeş C.; Söyüt H.; Beydemir S.
In this study, we investigated the effects of the drugs, palonosetron hydrochloride, bevacizumab and cyclophosphamide, on human serum paraoxonase-I (hPON1) enzyme activity in in vitro conditions. The enzyme was purified ~231-fold with 34.2% yield by using ammonium sulphate precipitation, DEAE-Sephadex A-50 ion-exchange chromatography and Sephadex G-200 gel-filtration chromatography from human serum. hPON1 exhibited a single protein band on the SDS polyacrylamide gel electrophoresis. The inhibition studies were performed on paraoxonase activity of palonosetron hydrochloride, bevacizumab and cyclophosphamide. Ki constants were found as 0.033 ± 0.001, 0.054 ± 0.003 mM and 3.419 ± 0.518 mM, respectively. Compared to the inhibition rates of the drugs, palonosetron hydrochloride has the maximum inhibition rate. However, inhibition mechanisms of the drugs were determined as noncompetitive by Lineweaver-Burk curves. © 2016 Elsevier B.V.
New water mites of the family Hygrobatidae (Acari, Hydrachnidia) from Turkey
(2013) Esen Y.; Peši? V.; Erman O.; Kaya Y.
In this study, the findings of three water mite species of the family Hygrobatidae collected from different streams in Turkey were evaluated. Hygrobates (s. str.) anatolicus Esen & Peši?, sp. n. is described as new for science. Hygrobates (Rivobates) diversiporus Sokolow, 1927 and Atractides (s. str.) nikooae Peši?, 2004, which were illustrated and thoroughly discussed, are new records for the Turkish fauna. © Yunus Esen et al.
Surface and optical properties of indium tin oxide layer deposition by RF magnetron sputtering in argon atmosphere
(Springer Verlag, 2016) Yudar H.H.; Korkmaz Ş.; Özen S.; Şenay V.; Pat S.
This study focused on the characterization and properties of transparent and conductive indium tin oxide (ITO) thin films deposited in argon atmosphere. ITO thin films were coated onto glass substrates by radio frequency (RF) magnetron sputtering technique at 75 and 100 W RF powers. Structural characteristics of producing films were investigated through X-ray diffraction analysis. UV–Vis spectrophotometer and interferometer were used to determine transmittance, absorbance and reflectance values of samples. The surface morphology of the films was characterized by atomic force microscope. The calculated band gaps were 3.8 and 4.1 eV for the films at 75 and 100 W, respectively. The effect of RF power on crystallinity of prepared films was explored using mentioned analysis methods. The high RF power caused higher poly crystallinity in the produced samples. The thickness and refractive index values for all samples increased respect to an increment of RF power and were calculated as 20, 50 nm and 1.71, 1.86 for samples at 75 and 100 W, respectively. Finally, the estimated grain sizes for all prepared films decreased with increasing of 2? degrees, and the number of crystallite per unit volume was calculated. It was found that nearly all properties including sheet resistance and resistivity depend on the RF power. © 2016, Springer-Verlag Berlin Heidelberg.
Highly Enantioselective Production of Chiral Secondary Alcohols with Candida zeylanoides as a New Whole Cell Biocatalyst
(Wiley-VCH Verlag, 2017) Şahin E.; Dertli E.
The increasing demand for biocatalysts in synthesizing enantiomerically pure chiral alcohols results from the outstanding characteristics of biocatalysts in reaction, economic, and ecological issues. Herein, fifteen yeast strains belonging to three food originated yeast species Candida zeylanoides, Pichia fermentans, and Saccharomyces uvarum were tested for their capability for asymmetric reduction of acetophenone to 1-phenylethanol as biocatalysts. Of these strains, C. zeylanoides P1 showed an effective asymmetric reduction ability. Under optimized conditions, substituted acetophenones were converted to corresponding optically active secondary alcohols in up to 99% enantiomeric excess and at high yields. The preparative scale asymmetric bioreduction of 4-nitroacetophenone (1m) by C. zeylanoides P1 gave (S)-1-(4-nitrophenyl)ethanol (2m) with 89% yield and > 99% enantiomeric excess. Compound 2m has been obtained in an enantiomerically pure and inexpensive form. Additionally, these results indicate that C. zeylanoides P1 is a promising biocatalyst for the synthesis of chiral alcohols in industry. © 2017 Wiley-VHCA AG, Zurich, Switzerland
Investigation of the effect of RF energy on optical, morphological, chemical and antibacterial properties of PolyTerpenol thin films obtained by RF-PECVD technique
(Springer New York LLC, 2018) Bayram O.; Simsek O.
In this study, it was aimed to obtain PolyTerpenol thin films by radio frequency plasma enhanced chemical vapor deposition technique using Terpinen-4-ol essential oil, which is organic compounds. The surface morphology and chemical properties of polymer thin films were investigated by atomic force microscopy (AFM) and Fourier transform infrared spectroscopy. AFM analyzes of PolyTerpenol thin films revealed that the thin films are homogeneous, smooth and nonporous. The optical properties of the thin films were determined using UV–Vis spectrophotometer. When optical band gaps of thin films were examined, it was found that this value varied from 3.83 to 3.20 eV. The extinction coefficients of the obtained thin films according to the increasing RF energy were calculated as 0.0011, 0.0060, 0.0085 and 0.0150, respectively, at a wavelength of 320 nm. In addition, antibacterial effects of these thin films against Escherichia Coli (E.Coli) bacteria were also investigated. The PolyTerpenol thin films were found to have high antibacterial activity against E. Coli bacteria. © 2018, Springer Science+Business Media, LLC, part of Springer Nature.
An experimental and theoretical investigation of Acenaphthene-5-boronic acid: Conformational study, NBO and NLO analysis, molecular structure and FT-IR, FT-Raman, NMR and UV spectra
(Elsevier B.V., 2013) Karabacak M.; Sinha L.; Prasad O.; Asiri A.M.; Cinar M.
The solid state Fourier transform infrared (FT-IR) and FT-Raman spectra of Acenaphthene-5-boronic acid (AN-5-BA), have been recorded in the range 4000-400 cm1 and 4000-10 cm 1, respectively. Density functional theory (DFT), with the B3LYP functional was used for the optimization of the ground state geometry and simulation of the infrared and Raman spectra of the molecule. The vibrational wave numbers and their assignments were examined theoretically using the Gaussian 09 set of quantum chemistry codes and the normal modes were assigned by a scaled quantum mechanical (SQM) force field approach. Hydrogen-bonded dimer of AN-5-BA, optimized by counterpoise correction, has also been studied by B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H·O hydrogen bonding have been discussed. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by Gauge-Including Atomic Orbital (GIAO) method. Natural bond orbital (NBO) analysis has been applied to study stability of the molecule arising from charge delocalization. UV spectrum of the title compound was also recorded and the electronic properties, such as frontier orbitals, and band gap energies were measured by TD-DFT approach. The first order hyperpolarizability (?), its components and associated properties such as average polarizability and anisotropy of the polarizability (? and ??) of AN-5-BA was calculated using the finite-field approach. © 2013 Elsevier B.V. All rights reserved.
Electrorheological Fluids Equations Involving Variable Exponent with Dependence on the Gradient via Mountain Pass Techniques
(Taylor and Francis Inc., 2016) Mashiyev R.A.; Ekincioglu I.
This article deals with a quasilinear elliptic equation with variable exponent under a homogenous Dirichlet boundary-value condition, where nonlinearity also depends on the gradient of the solution. By using an iterative method based on Mountain Pass techniques, the existence of a positive solution is obtained. © 2016, Copyright © Taylor & Francis Group, LLC.
Enhanced Pinning Properties of Laser-Irradiated Bulk MgB2 Superconductors
(Springer New York LLC, 2017) Erdem O.; Yanmaz E.
In order to investigate the effect of laser irradiation on the superconducting properties of MgB2, a pellet-shaped sample was produced and cut into two pieces. The dot-shaped molten patterns, with the distance of 100 µm between them, were formed on the surface of one of the pieces by using an Nd:YVO4 laser. The grains of the irradiated sample were significantly grown due to the laser-induced sintering. The modified surface appeared to have dense and compacted grains as a result of increasing interconnectivity among the superconducting grains. The critical current densities at 5 K in a field of 3 T were found to be 5.38 × 104 and 8.96 × 104 A cm?2 for the reference and the irradiated samples, respectively. The increment of critical current density for the irradiated sample is presumably connected with the changing of pinning mechanism after the laser irradiation. For the irradiated sample which showed a higher value of critical current density at 5 K under high fields, ?? pinning was obtained as a dominant pinning mechanism, while the normal point pinning was dominant for the reference one. These results point out that the superconducting properties of bulk MgB2 can be changed and improved via laser irradiation in a short time. © 2016, Springer Science+Business Media New York.
Direct and fast growth of GaAs thin films on glass and polyethylene terephthalate substrates using a thermionic vacuum arc
(Springer New York LLC, 2015) Pat S.; Korkmaz Ş.; Özen S.; Şenay V.
Using a thermionic vacuum arc, single?crystal gallium arsenide (GaAs) layers of micron thickness were grown on PET and glass substrates in 2 min. We present a new deposition mechanism and parameters for GaAs thin films produced in a very short time. Crystal direction was found to be (111) plane for the GaAs/PET sample and (022) plane and (133) plane for the GaAs/glass sample, respectively. The average roughness values of the deposited thin films were determined to be approximately 30 nm for GaAs/PET and 60 nm for GaAs/glass. The structures can be seen clearly in field emission scanning electron microscopy and atomic force microscopy. The obtained optical band is nearly the same with literatures values of the GaAs. Although produced structures in different crystal formations, only aggregations dimensions and absorbance of the layers were changed. Obtained refractive index values are nearly same with database info. © 2015, Springer Science+Business Media New York.
Development of teacher academic optimism scale: The validity and reliability study
(Pegem Akademi Yayincilik Egitim Danismanlik Hizmetleri, 2018) Ergen Y.; Elma C.
The study aims to develop a valid and reliable academic optimism scale that can be used to determine teachers' academic optimism levels. The study was conducted through a total number of 404 primary school teachers who worked in the central districts of Malatya Province during 2014-2015 academic year. The content validity and face validity of the scale were determined via expert recommendations. An explanatory factor analysis and a confirmatory factor analysis were conducted to determine the construct validity of the scale. After the expert opinions, 80 items reduced to 64 and the data was collected by the use of these 64 items. An exploratory factor analysis revealed 5 factors reducing 64 items in to 33 and explaining 58.56% of the total variation in the data. The five-factor model obtained through an explanatory factor analysis after removal of one item as a result of the confirmatory factor analysis was observed to be highly consistent. Different from previous related research, the result showed that a new dimension as "Maneger Trust" emerged as a part of "Teacher Academic Optimism Scale". And finally this scale could be used as a valid and reliable instrument in the future studies.
Examination of absorption effects at the Compton to coherent scattering intensities X-rays using Fe-Ca and Fe-Ti binary compounds with WDXRF
(American Institute of Physics Inc., 2017) Boydaş E.; Boydaş M.G.; Allm B.
Matrix absorption effects have been examined with scattered X-rays by using WDXRF system for Fe-Ca and Fe-Ti binary compounds. Fe as analyte and elements which some of them the K absorption edge just below the characteristic K X-ray energies of the analyte (Fe) as matrix have been chosen. Pure and binary with Fe ratio ranging from 10% to 90% samples were prepared with these elements. These samples have been analyzed in WDXRF system. At the end of measurement, the coherent and Compton scattering X-rays data of Rh K? X-rays from these samples have been obtained. Matrix absorption effects have been examined by calculating coherent / Compton scattered X-rays intensity ratio. © 2017 Author(s).
The role of cobalt doping on the optical and structural properties of Mn 3 O 4 nanostructured thin films obtained by SILAR technique
(Academic Press, 2019) Özkan, Bayram; İgman E.; Guney H.; Simsek O.
Cobalt doped manganese oxide thin films (Mn 3 O 4 :Co) were successfully deposited on soda lime glass substrates using SILAR technique. Mn 3 O 4 :Co thin films were characterized using XRD, SEM, Uv–VIS and Raman spectroscopy. The XRD spectra showed that thin films had substantially Hausmannite crystal structure. The preferential orientation of the pure and 0.5 at.% Co doped manganese oxide thin films (Mn 3 O 4 ) was (002), but with increasing Co doping, it was detected that this preferential orientation shift towards the (211) plane. The absorbance, transmittance and optical band gap of the Mn 3 O 4 :Co thin films were determined using Uv–Vis spectroscopy and these properties of the thin films differed considerably due to cobalt doping. The optical band gap of pure Mn 3 O 4 thin films was 2.00 eV, but on the other hand, due to the Co doping this value increased before and then decreased slightly. Optical transmittance of Mn 3 O 4 :Co films increased from 60% to 72% with the effect of Co doping. A1g mode, which is the characteristic vibration peak of Mn 3 O 4 films, was confirmed for pure and doped Mn 3 O 4 thin films at a wavelength of 658 nm. © 2019 Elsevier Ltd
Heavily carbon doped GaAs nanocrystalline thin film deposited by thermionic vacuum arc method
(Elsevier Ltd, 2016) Pat S.; Korkmaz Ş.; Özen S.; Şenay V.
In this paper, we introduced a new different thin film deposition method for heavily carbon doped GaAs. Used method is thermionic vacuum arc (TVA) and first used for the carbon doping process. The method is very fast deposition process for the other growth method such as metal organic chemical vapor deposition, molecular beam epitaxy, molecular organic molecular beam epitaxy. The smallest grain size of GaAs and doped GaAs were obtained by carbon doping process. Mean crystalline size and height of crystalline size were found to be 3.4 nm and 4 nm, respectively. Crystal direction was found to be (022) plane and (024) plane for the sample at 45.322° and 75.060°, respectively. The production process and obtained results show that used methods is very simple, low cost, eco friendly and very fast method for the carbon doped GaAs. © 2015 Elsevier B.V.
Effects of grain size on room temperature deformation behavior of Zn–22Al alloy under uniaxial and biaxial loading conditions
(Elsevier Ltd, 2016) Cetin M.E.; Demirtas M.; Sofuoglu H.; Cora Ö.N.; Purcek G.
Effects of grain size on room temperature (RT) deformation behavior of superplastic Zn–22Al alloy under uniaxial and biaxial loading conditions were investigated. Two–step equal channel angular pressing (ECAP) and subsequent annealing processes were applied to the alloy in order to obtain microstructures with various grain sizes ranging from submicron to micron sizes. Grain size of 200 nm was achieved after ECAP of the alloy, and it was increased up to ~2.60 µm by annealing at 250 °C for different time periods. Changes in deformation behaviors of the alloy with various grain sizes were found to be in good agreement under the uniaxial tensile and biaxial Erichsen test conditions. Increasing grain size decreased both the maximum elongation under uniaxial deformation and limiting dome height (LDH) under biaxial deformation. The high elongation to failure and LDH values for the samples with submicron grain size were attributed to their high strain rate sensitivity. © 2016 Elsevier B.V.
Taguchi Approach for Optimization of Parameters that Effect Grain Size of Cast A357 Alloy
(De Gruyter Open Ltd, 2017) Çolak M.; Dlşplnar D.
Grain refining and modification are common foundry practice for improving properties of cast Al-Si alloys. In general, these types of treatments provide better fluidity, decreased porosity, higher yield strength and ductility. However, in practice, there are still some discrepancies on the reproducibility of the results from grain refining and effect of the refiner's additions. Several factors include the fading effect of grain refinement and modifiers, inhomogeneous dendritic structure and non-uniform eutectic modification. In this study, standard ALCAN test was used by considering Taguchi's experimental design techniques to evaluate grain refinement and modification efficiency. The effects of five casting parameters on the grain size have been investigated for A357 casting alloy. The results showed that the addition of the grain refiner was the most effective factor on the grain size. It was found that holding time, casting temperature, alloy type and modification with Sr were less effective over grain refinement. © by M. Çolak 2018.
Optimum design of composite steel frames with semi-rigid connections and column bases via genetic algorithm
(Techno Press, 2015) Artar M.; Dalo?lu A.T.
A genetic algorithm-based minimum weight design method is presented for steel frames containing composite beams, semi-rigid connections and column bases. Genetic Algorithms carry out optimum steel frames by selecting suitable profile sections from a specified list including 128 W sections taken from American Institute of Steel Construction (AISC). The displacement and stress constraints obeying AISC Allowable Stress Design (ASD) specification and geometric (size) constraints are incorporated in the optimization process. Optimum designs of three different plane frames with semi-rigid beam-to-column and column-to-base plate connections are carried out first without considering concrete slab effects on floor beams in finite element analyses. The same optimization procedures are then repeated for the case of frames with composite beams. A program is coded in MATLAB for all optimization procedures. Results obtained from the examples show the applicability and robustness of the method. Moreover, it is proved that consideration of the contribution of concrete on the behavior of the floor beams enables a lighter and more economical design for steel frames with semi-rigid connections and column bases. Copyright © 2015 Techno-Press, Ltd.
Effect of XRD relative intensities of the Li (002) on surface, optical and electrochemical impedance spectroscopy analyses of the deposited LiCoO2 thin film
(Springer New York LLC, 2017) Yudar H.H.; Pat S.; Özen S.; Şenay V.; Korkmaz Ş.; Pat Z.
In this paper, the effect of RF power on LiCoO2 thin films was investigated using X-ray diffractometer (XRD), atomic force microscopy, UV–Vis spectrophotometer, and potentiostat. The microstructural, surface, optical and electrochemical impedance measurements were performed to LiCoO2 thin films, are used to for the fully solid-state battery cathode material. According to obtained results, the relative intensities of the Li (002) crystal phase in XRD patterns of deposited LiCoO2 thin films were increased by increasing applied RF power, for the first time. The intensity of the LiCoO2 (104) plane is nearly invariant. The relative intensities of the LiCoO2 (113) plane were decreased by increasing RF power. The peak locations of the Li (002) and LiCoO2 (104) were not changed. It was found that Li (002) relative intensities affect the all investigated parameters for the LiCoO2 thin films. Especially, transmittance value increased about 20%. The band gap of the deposited film was changed 100–300 meV drastically. Deposited samples are shown high transparency in the visible region. Randles circuit was used for the equivalent circuit model. Nyquist plots, fitting parameters values and value of the circuit elements were estimated by ZSim software. © 2017, Springer Science+Business Media New York.

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