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Article Citation - WoS: 29Citation - Scopus: 31Composition-tuned band gap energy and refractive index in GaSxSe1-x layered mixed crystals(Elsevier Science Sa, 2017) Isik, Mehmet; Gasanly, NizamiTransmission and reflection measurements on GaSxSe1-x mixed crystals (0 <= x <= 1) were carried out in the 400-1000 nm spectral range. Band gap energies of the studied crystals were obtained using the derivative spectra of transmittance and reflectance. The compositional dependence of band gap energy revealed that as sulfur (selenium) composition is increased (decreased) in the mixed crystals, band gap energy increases quadratically from 1.99 eV (GaSe) to 2.55 eV (GaS). Spectral dependencies of refractive indices of the mixed crystals were plotted using the reflectance spectra. It was observed that refractive index decreases nearly in a linear behavior with increasing band gap energy for GaSxSe1-x mixed crystals. Moreover, the composition ratio of the mixed crystals was obtained from the energy dispersive spectroscopy measurements. The atomic compositions of the studied crystals are well-matched with composition x increasing from 0 to 1 by intervals of 0.25. (C) 2016 Elsevier B.V. All rights reserved.Article Citation - WoS: 49Citation - Scopus: 55Synthesis of Α-fe2o3< Heterogeneous Composites by the Sol-Gel Process and Their Photocatalytic Activity(Elsevier Science Sa, 2020) Bouziani, Asmae; Park, Jongee; Ozturk, Abdullahalpha-Fe2O3/TiO2 heterogeneous composites were synthesized by the sol-gel process to increase the photocatalytic activity of TiO2. The structural, morphological, and optical characteristics of the composites were determined by X-ray diffraction, scanning electron microscope, and UV-vis diffuse reflectance spectroscopy. Results revealed that the incorporation of alpha-Fe2O3 to TiO2 widened the visible light absorption ability of TiO2. It was realized that the calcination temperature plays a crucial role in morphology development hence photocatalytic activity of the alpha-Fe2O3/TiO2 heterogeneous composites. The photocatalytic activity of the composites calcined at various temperatures was evaluated for the degradation of Methylene Blue (MB) and Phenol (Ph) in aqueous medium under UV and sun-like illuminations. The alpha-Fe2O3-TiO2 composites exhibits superior photocatalytic efficiency to degrade both MB and Ph as compared to both pristine TiO2 and pristine alpha-Fe2O3 under sun-like illumination. The alpha-Fe2O3/TiO2 composite degraded approximately 90 % of MB and 50 % of Ph in 180 min sun-like illumination. Improvement in photocatalytic activity is attributed to the separation of photogenerated electron/hole pairs through the interaction of alpha-Fe(2)O(3 )and TiO2.Article Citation - WoS: 9Citation - Scopus: 10Characterization of Properties of Vanadium, Boron and Strontium Addition on Hpdc of A360 Alloy(Elsevier Science Sa, 2021) Gursoy, Ozen; Colak, Murat; Tur, Kazim; Dispinar, DeryaThe demand for lighter weight decreased thickness and higher strength has become the focal point in the automotive industry. In order to meet such requirements, the addition of several alloying elements has been started to be investigated. In this work, the additions of V, B, and Sr on feedability and tensile properties of A360 has been studied. A mold design that consisted of test bars has been produced. Initially, a simulation was carried out to optimize the runners, filling, and solidification parameters. Following the tests, it was found that V addition revealed the highest UTS but low elongation at fracture, while B addition exhibited visa verse. On the other hand, impact energy was higher with B additions.Article Citation - WoS: 5Citation - Scopus: 6An Electrochromic Polymer Based on Cyclopenta[2,1-B;3,4 Effect of a Single Atom Alteration on the Electrochemical and Optical Properties of the Polymer Backbone(Elsevier Science Sa, 2020) Tutuncu, Esra; Varlik, Bengisu; Kesimal, Busra; Cihaner, Atilla; Ozkut, Merve IcliAn electrochromic polymer, namely "poly(2,6-(3,3-didecyl-3,4-dihydro-2H-thieno [3,4-b] [1,4]dioxepin-6-yl)-4,4-dioctyl-4H-cyclopenta[2,1-b;3,4-b']dithiophene)" (P1), was electrochemically synthesized successfully, and its electrochemical and optical properties were investigated. The band gap of the polymer P1 was calculated as 1.77 eV with -5.45 eV Highest Occupied Molecular Orbital (HOMO) and -3.68 eV Lowest Unoccupied Molecular Orbital (LUMO) energy levels. The polymer P1 is bluish purple when neutralized and highly transparent greenish purple when oxidized. This color change was observed around 1.4 s between its redox states and optical contrast ratio was found to be as 49 % and 53 % with 234 cm(2)/C and 239 cm(2)/C coloration efficiencies at 590 nm and 634 nm, respectively. Moreover, the properties of this polymer were compared to its analogues and also during this comparison the effect of alteration of a single atom in the pendant unit was tried to be understood.Article Citation - WoS: 62Citation - Scopus: 69Molecularly Imprinted Biocompatible Magnetic Nanoparticles for Specific Recognition of Ochratoxin a(Elsevier Science Sa, 2016) Turan, Eylem; Sahin, FeratIn this paper, we synthesized highly selective oligo(ethylene glycol) monomethyl ether methacrylate (OEGMA) based molecularly imprinted polymers for carcinogenic mycotoxin Ochratoxin A (OTA) on the surface of magnetic nanoparticles (MIP MNPs) via surface initiated atom transfer radical polymerization (SI-ATRP). Functional monomer OEGMA, crosslinker 1,2-ethyleneglycoldimethacrylate (EGDMA), template molecule OTA, initiator 3-bromopropyltrimethoxysilane (BPTS), Cu(I)Br and 2,2'-bipyridyl(2,2'-bpy) were selected for synthesis the MIP layer onto the surface of MNPs. After removing the template, the molecularly imprinted magnetic nanoparticles was used to detect OTA using UV-vis spectrophotometer. According to results, MIP MNPs showed fast adsorption, large adsorption capacity and highly selectivity toward to OTA. Also, the recovery of OTA in the spiked grape juice samples ranged from 97.1% to 97.4% with the relative standard deviation changed from 4.13% to 6.25%. As a result, MIP MNPs demonstrate high affinity to OTA targets have significant potential for clean-up applications in food samples (C) 2015 Elsevier B.V. All rights reserved.Article Citation - WoS: 5Citation - Scopus: 5Low-Temperature Thermoluminescence in Layered Structured Ga0.75in0.25< Single Crystals(Elsevier Science Sa, 2012) Isik, M.; Bulur, E.; Gasanly, N. M.Defect centers in Ga0.75In0.25Se single crystals have been studied performing the thermoluminescence measurements in the temperature range of 10-300 K. The observed glow curves were analyzed using curve fitting, initial rise, and different heating rate methods to determine the activation energies of the defect centers. Thermal cleaning process has been applied to decompose the overlapped curves. Four defect centers with activation energies of 9, 45,54 and 60 meV have been found as a result of the analysis. The capture cross sections and attempt-to-escape frequencies of the defect centers were also found using the curve fitting method under the light of theoretical predictions. The first order kinetics for the observed glow curve was revealed from the consistency between the theoretical predictions for slow retrapping and experimental results. Another indication of negligible retrapping was the independency of peak position from concentration of carriers trapped in defect levels. (C) 2012 Elsevier B.V. All rights reserved.Article Citation - WoS: 2Citation - Scopus: 2Investigation of the Effectiveness of Pcm on the Energy Saving, Thermal Comfort and Indoor Air Quality in Overcrowded Area(Elsevier Science Sa, 2023) Al-Malaki, Fadhil A. M. K.; Hussen, Hasanen M.; Turkakar, Goker; Jafari, RahimOvercrowded areas like hospitals, jails, and shelter elevators pose a risk in terms of excessive temperatures, excessive CO2 concentrations, or even the presence of toxins and viruses. Hence, ventilation, thermal comfort and energy management are crucial issues for these kinds of places. In the present study, a prototype (1:4) of a prison quarry located in Baghdad, Iraq has been examined. Indoor air quality, humidity, temperature distribution and energy consumption of the room have been monitored for the identical weather conditions of the real prison cell, including five dummy occupants, each dissipating 100 W/m2 of heat, releasing CO2 of 0.3 l/min and water vapor. To reduce the cooling energy consumption of the building and the temperature deviation during the day, two layers of Phase Change Materials, PCMs, have been embedded in the ceiling of the prototype. Experiments have been recorded for three hours in Baghdad's harsh weather conditions in August. In addition, numerical analyses were conducted and compared with experimental findings, and a good match is obtained. Energy saving of 47.2% have been calculated by using PCM for the inlet air velocity of 0.5 m/s.Article Citation - WoS: 29Citation - Scopus: 29The investigation of electronic, anisotropic elastic and lattice dynamical properties of MAB phase nanolaminated ternary borides: M 2 AlB 2 ( M = Mn , Fe and Co ) under spin effects(Elsevier Science Sa, 2020) Surucu, Gokhan; Yildiz, Bugra; Erkisi, Aytac; Wang, Xiaotian; Surucu, Ozge[No Abstract Available]Article Citation - WoS: 9Citation - Scopus: 9Experimental and Theoretical Investigation of the Mechanical Characteristics of Sillenite Compound: Bi12geo20<(Elsevier Science Sa, 2021) Surucu, Gokhan; Isik, Mehmet; Gencer, Aysenur; Gasanly, NizamiThe present study reports the mechanical and elastic characteristics of Bi12GeO20 (BGO) compound by experimental nanoindentation measurements and density functional theory (DFT) calculations. X-ray diffraction pattern of BGO was plotted and revealed diffraction peaks were associated with Miller indices of cubic crystalline structure with lattice constant of a = 10.304 angstrom. Two- and three-dimensional representations of Young's modulus, linear compressibility, shear modulus and Poisson's ratio were presented according to DFT calculations. The calculated elastic constants pointed out the mechanically stable and anisotropic behavior of the BGO. The hardness and Young's modulus ranges of the BGO calculated from DFT studies were found as 3.7-6.3 GPa and 61.7-98.9 GPa, respectively. Hardness and Young's modulus of BGO single crystal were also obtained by analyzing force-dependent nanoindentation experimental data. It was observed that hardness and Young's modulus decrease with increase of load in the low applied loads and then reaches saturation in the high applied loads. This behavior is known as indentation size effect. True hardness value was determined from proportional specimen resistance model as 4.1 GPa. The force independent region presented the Young's modulus as 114 GPa. (C) 2021 Elsevier B.V. All rights reserved.Article Citation - WoS: 5Citation - Scopus: 5Acoustic Phonons Scattering Mobility and Carrier Effective Mass in In6s7< Crystals(Elsevier Science Sa, 2006) Qasrawi, A. F.; Gasanly, N. M.Systematic dark electrical resistivity and Hall coefficient measurements have been carried out in the temperature range of 170-320 K on n-type In6S7 crystals. The analysis of the electrical resistivity and carrier concentration reveals the intrinsic type of conduction with an average energy band gap of similar to 0.75 eV The carrier effective masses of the conduction and valence bands were calculated from the intrinsic temperature-dependent carrier concentration data and were found to be 0.565m(0) and 2.020m(0), respectively. The temperature-dependent Hall mobility was observed to follow the mu alpha T-3/2 law and was analyzed assuming the domination of acoustic phonons scattering. The acoustic phonons scattering mobility was calculated from the crystal's structural data with no assumptions. The experimental Hall mobility data of In6S7 crystals coincides with the theoretical acoustic phonons scattering mobility data with acoustic deformation potential of 6.4 eV. (c) 2006 Elsevier B.V. All rights reserved.
