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Article Citation - Scopus: 1Infrared and Raman Scattering Spectra of Layered Structured Ga3inse4< Crystals(Elsevier Science Bv, 2013) Isik, M.; Gasanly, N. M.; Korkmaz, F.The infrared reflectivity and transmittance and Raman scattering in Ga3InSe4 layered crystals were investigated in the frequency ranges of 100-400, 400-4000 and 25-500 cm(-1). The refractive and absorption indices, the frequencies of transverse and longitudinal optical modes, high- and low-frequency dielectric constants were obtained from the analysis of the IR reflectivity spectra. The bands observed in IR transmittance spectra were interpreted in terms of two-phonon absorption processes. (C) 2012 Elsevier B.V. All rights reserved.Article Citation - WoS: 7Citation - Scopus: 7Design of the Zns/Ge pn Interfaces as Plasmonic, Photovoltaic and Microwave Band Stop Filters(Elsevier Science Bv, 2017) Alharbi, S. R.; Qasrawi, A. F.In the current work, we report and discuss the features of the design of a ZnS (300 nm)/Ge (300 nm)/GaSe (300 nm) thin film device. The device is characterized by the X-ray diffraction, electron microscopy, energy dispersive X-ray spectroscopy (EDS), optical spectroscopy, microwave power spectroscopy and light power dependent photoconductivity. While the X-ray diffraction technique revealed a polycrystalline ZnS coated with two amorphous layers of Ge and GaSe, the hot probe tests revealed the formation of pn interface. The optical spectra which were employed to reveal the conduction and valence band offsets at the ZnS/Ge and Ge/GaSe interface indicated information about the dielectric dispersion at the interface. The dielectric spectra of the ZnS/Ge/GaSe heterojunction which was modeled assuming the domination of surface plasmon interactions through the films revealed a pronounced increase in the drift mobility of free carriers in the three layers compared to the single and double layers. In the scope of the fitting parameters, a wave trap that exhibit filtering properties at notch frequency of 2.30 GHz was designed and tested. The ac signals power spectrum absorption reached similar to 99%. In addition, the photocurrent analysis on the ZnS/Ge/GaSe interface has shown it is suitability for photovoltaic and photosensing applications. (C) 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND licenseArticle Citation - WoS: 3Citation - Scopus: 3Dielectric Dispersion and Energy Band Gap of Bi1.5-x< Solid Solution(Elsevier Science Bv, 2014) Qasrawi, A. F.; Mergen, A.The optical transmittance and reflectance spectra of samarium doped bismuth-zinc-niobium-oxide (BZN) pyrochlore ceramics are investigated in the wavelength range of 200-1050 nm (200-1500 THz). The Sm content in the Bi1.5-xSmxZn0.92Nb1.5O6.92 solid solution significantly alters the optical properties. Therefore, increasing the Sm doping ratio from x=0.10 to x=0.13 decreased the indirect forbidden energy band gap from 3.60 to 3.05 eV. In addition, above 350 THz, increasing the Sin content decreases the dielectric constant values and alters the dielectric dispersion parameters. The dielectric spectra which were evaluated in the frequency range of 200-1500 THz reflected a sharp decrease in the dielectric constant with increasing frequency clown to 358 THz. The spectra reflected a resonance peak at this frequency. Such resonance spectrum is promising for technological applications as it is close to the illumination of 870 am IR lasers that are used in optical communications. The calculated oscillator (E-o) and dispersion (E-d) energies near that critical range (375-425 THz) reflected an increase in both E-o and E-d with increasing Sm content. (C) 2014 Elsevier B.V. All rights reserved.Article Citation - WoS: 2Citation - Scopus: 2On Unfair Permutations(Elsevier Science Bv, 2018) Arslan, Ilker; Islak, Umit; Pehlivan, CihanIn this paper we study the inverse of so-called unfair permutations. Our investigation begins with comparing this class of permutations with uniformly random permutations, and showing that they behave very much alike in case of locally dependent random variables. As an example of a globally dependent statistic we use the number of inversions, and show that this statistic satisfies a central limit theorem after proper centering and scaling. (C) 2018 Elsevier B.V. All rights reserved.Article Citation - WoS: 8Citation - Scopus: 11Joint Distribution of Run Statistics in Partially Exchangeable Processes(Elsevier Science Bv, 2011) Eryilmaz, SerkanLet {X-i}(i >= 1) be an infinite sequence of recurrent partially exchangeable random variables with two possible outcomes as either "1" (success) or "0" (failure). In this paper we obtain the joint distribution of success and failure run statistics in {X-i}(i >= 1). The results can be used to obtain the joint distribution of runs in ordinary Markov chains, exchangeable and independent sequences. (C) 2010 Elsevier B.V. All rights reserved.Article Citation - WoS: 125Citation - Scopus: 130Pdau-mnox< Nanoparticles Supported on Amine-Functionalized Sio2 for the Room Temperature Dehydrogenation of Formic Acid in the Absence of Additives(Elsevier Science Bv, 2016) Karatas, Yasar; Bulut, Ahmet; Yurderi, Mehmet; Ertas, Ilknur Efecan; Alal, Orhan; Gulcan, Mehmet; Zahmakiran, MehmetFormic acid (HCOOH) has recently been suggested as a promising hydrogen carrier for fuel cell applications. However efficient hydrogen production through the decomposition of formic acid in the absence of additives under mild thermodynamic conditions constitutes a major challenge because of the ease poisoning of active metals with CO formed as intermediate during formic acid decomposition. Recently, we have reported (App. Catal. B: Env. 164 (2015) 324) our discovery that the separately nucleated MnOx nanoparticles act as CO-sponge around catalytically active Pd nanoparticles exist on the same support and enhances both the activity and CO-resistivity of Pd nanoparticles. Using this important finding, herein, we present a new catalyst system consists of the physical mixture of PdAu alloy and MnOx nanoparticles supported on amine-grafted silica (PdAu-MnOx/N-SiO2) for the room temperature dehydrogenation of formic acid in the absence of any additives. PdAu-MnOx/N-SiO2 catalyst was simply prepared by deposition-reduction technique in water at room temperature with high reproducibility and characterized by the combination of various spectroscopic tools including ICP-OES, P-XRD, DR/UV-vis, XPS, BFTEM, STEM-EDX, STEM-line analysis and CO-stripping voltammetry techniques. The sum of their results shows that the formation of physical mixture of PdAu alloy and MnOx (dmean=2.2 nm) nanoparticles on the surface of support material. This new catalytic material facilitates the hydrogen liberation through the additive-free formic acid dehydrogenation at room temperature with previously unprecedented activity (TOF=785 mol H-2 mol catalyst(-1) h(-1)), converging to that of the existing state of the art homogenous catalysts. This new superior catalytic system enables facile catalyst recovery and very high stability against agglomeration, leaching and CO poisoning, which make it highly reusable catalyst (retains >92% activity and 85% conversion at the 5th catalytic reuse) in the additive-free formic acid dehydrogenation at room temperature. (C) 2015 Elsevier B.V. All rights reserved.Article Citation - WoS: 7Citation - Scopus: 9Thermoluminescence Study in Cu3ga5< Single Crystals: Application of Heating Rate and tm< Methods(Elsevier Science Bv, 2018) Isik, M.; Gasanly, N. M.; Gasanova, L. G.; Mahammadov, A. Z.Cu3Ga5S9 semiconducting single crystals were investigated using thermoluminescence (TL) measurements in 10-300 K temperature region. In the TL glow curve, one peak starting to appear at the instant temperature is increased from 10 K and another peak, which is broader than a general individual TL peak, were observed. The broad peak around 66 K was investigated using T-m-T-stop experimental method to understand whether or not this peak is composed of more than one individual peaks or continuously distributed traps. Curve fitting, initial rise and peak shape methods were used for acceptable TL curves to be analyzed. TL curves in T-m-T-stop method indicated that observed peaks are due to the existence of quasi-continuous distribution of traps. Structural characterizations of Cu3Ga5S9 single crystals were studied using x-ray diffraction and energy dispersive spectroscopy measurements. The crystal structure, lattice parameters and atomic composition of the elements were reported in the present paper.Conference Object Citation - WoS: 12A Study on Factors Affecting the Internationalization Process of Small and Medium Enterprises (smes)(Elsevier Science Bv, 2015) Kunday, Ozlem; Senguler, Ece PiskinsutAs a result of the rapid prevalence of Information Technologies, disappearance of the borders between countries as a sequel of globalization and the fast increase in the number of Small and Medium Sized Enterprises (SME)s, products and services similar to each other are emerging. Within such a context, firms are striving to increase the demand for their products and gain attention through differentiation both in local and global markets. Due to its important role in international trade of countries, SMEs are being considered as major role players in economies and therefore became an attractive area to explore by researchers. The literature on the internationalization of firms is predominantly build on research from the US and western European countries while there is a few number of research conducted in Turkey (Bal and Kunday, 2014; Senguler, 2013; Kocak and Abimbola, 2009; Cavusgil, Knight and Uner, 2011). The internationalization of SMEs has been mostly investigated within the marketing literature and there is a lack on this subject within the Management and Organization literature. Setting out from this need, the aim of this paper is to investigate the entrepreneurial skills of the entrepreneur who founded the SME, the motive of the entrepreneur for starting the business, the innovativeness of the firm, and the relationship of these factors with the internationalization of firms. The sample of the research consists of entrepreneurs who have been reached via the Global Entrepreneurship Monitor (GEM) study in 80 countries between the years 2000-2012. Hierarchical Regression Model was used to test the hypotheses at macro level including data from each country. Research findings and implications are presented and discussed. (C) 2015 The Authors. Published by Elsevier Ltd.Conference Object Citation - WoS: 21Citation - Scopus: 29Analysis of Elastic-Plastic Interference-Fit Joints(Elsevier Science Bv, 2014) Huyuk, Hava; Music, Omer; Koc, Asuman; Karadogan, Celalettin; Bayram, Cagdas; Karadoʇan, ÇelalettinThis paper presents an examination of the elastic-plastic interference fit joints for simple and complex pin-tube geometries. Mechanics of the process is studied in detail through physical trials and numerical models. Results show there are three distinct stages as the pin is pushed into the tube and that an optimum geometry maximising the joint strength exists. (C) 2014 The Authors. Published by Elsevier Ltd.Article Citation - WoS: 5Citation - Scopus: 7Temperature-Dependent Electrical Resistivity, Space-Charge Current and Photoconductivity of Ga0.75in0.25< Single Crystals(Elsevier Science Bv, 2013) Isik, M.; Gasanly, N. M.Dark electrical resistivity, space-charge-limited (SCL) current and photoconductivity measurements were carried out on Ga0.75In0.25Se single crystals. Analysis of the dark resistivity measurements revealed the presence of one level with activation energy of 0.10 eV. Current voltage characteristics showed that both ohmic and SCL characters exhibit in 180-300 K range. Analysis of the experimental data in the SCL region resulted with a trap level at 0.11 eV above the valence band. Photoconductivity measurements were performed at different light intensities in the temperature range of 150-300 K. Behavior of the recombination mechanism in the crystal was brought out as sublinear recombination from the dependence of photocurrent on illumination intensity. Moreover, obtained activation energies were compared with the results of other experimental techniques applied to Ga0.75In0.25Se crystals in literature. (C) 2013 Elsevier B.V. All rights reserved.
