Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
Browse
7 results
Search Results
Article Citation - WoS: 2Citation - Scopus: 4Identification of Turkish Extra Virgin Olive Oils Produced in Different Regions by Using Nmr (h-1 and C-13) and Irms (c-13/C-12)(Wiley, 2023) Sevim, Didar; Köseoğlu, Oya; Ertaş, Hasan; Özdemir, Durmuş; Ulaş, Mehmet; Günnaz, Salih; Çelenk, Veysel UmutIsotope ratio mass spectroscopy (IRMS) and nuclear magnetic resonance (NMR) spectroscopy techniques are two of the analytical methods that are used to characterize food products. The aim of this study is to classify extra virgin olive oil (EVOO) samples collected from different regions of Turkey based on H-1 and C-13 NMR spectra along with IRMS d(13)C carbon isotope ratio data by using chemometrics multivariate data analysis methods. A total of 175 EVOO samples were analyzed in 2014/15 and 2015/16 harvest seasons. Multivariate classification and clustering models were used to identify geographical and botanical origins of the EVOOs. IRMS results showed that there was no significant difference in terms of d(13)C values between the years in terms of harvest year (p > 0.05), only extraction phase and variety were statistically significant factors (p < 0.05). The interactions of the factors showed that the harvest year x variety interaction is important. The outcomes of this research clearly indicated that considering the partial least squares discriminant analysis result with NMR spectra, the percent success of the model in the South Marmara, North Aegean, and South Aegean region samples were 95%, 95.7%, and 96.4% in the model set, respectively. The results showed that by using classification and clustering models, geographic marking and labeling of these oils can be carried out regardless of differences in year and production systems (2 and 3 phase extraction system) according the NMR analysis.Article Citation - WoS: 3Citation - Scopus: 3Continuous Production of Hyperbranched Polyhydrocarbons by Electrochemical Polymerization of Chlorinated Methanes(Royal Society of Chemistry, 2022) Seo, Jae Hong; Nam, Hyun Ju; Rajendiran, Rajmohan; Seong, Won Kyung; Jiang, Yi; Kim, Min Hyeok; Büyükçakır, OnurA continuous production of polyhydrocarbon (PHC) by electrochemical polymerization of chlorinated hydrocarbons is presented. Monomer loading and product transfer were controlled by changing flow direction in a home-built continuous flow system that facilitates preparation, work-up, and scale-up of electrochemical polymerization. The polymerization can be tuned by adjusting reaction time, cell configuration, molar ratio of input chemicals, and the solvent type. CH2Cl2, CHCl3, and CCl4 were used to synthesize PHC. The reduction of the monomers at the cathode was studied by cyclic voltammetry and chronoamperometry. We investigated the structure and composition of PHCs from FT-IR and NMR spectra along with elemental analysis. Sufficient amounts of product are generated by continuous production and characterization of the product PHCs by a wide variety of methods is possible. Particularly, structural analysis by various C-13 NMR techniques suggests a new pathway for the synthesis of hyperbranched PHCs by electrochemical polymerization.Article Citation - WoS: 10Citation - Scopus: 7Assessment of Melt Cleanliness of Secondary 5000 Aluminum Alloy Via Non-Metallic Inclusions Characterization(Springer, 2023) Li, Cong; Dang, Thien; Huang, Jinxian; Huang, Chunfa; Li, Jianguo; Friedrich, Bernd; Gökelma, MertolThe extensive energy consumption of primary aluminum production stimulates increasing need of producing primary-quality alloys with secondary sources, during which process amount of non-metallic inclusions (NMIs) in the alloy must be strictly controlled. In the present study funded by AMAP Open Innovation Research Cluster, NMIs generated during remelting a 5000 Al-Mg alloy was investigated to offer benchmarking characters of NMIs with respect to type, morphology, size, composition, and concentration. Under different remelting conditions NMIs formed in the melt ahead of solidification were concentrated using Porous Disc Filtration Apparatus (PoDFA) and characterized microstructurally and quantitatively. Investigated conditions included heating cycle, organic contaminations, and refractory materials. Results suggested oxide films and cuboid particles as typical oxides with, respectively, different compositions. The amount of formed oxides declined with the increase of heating rate. With respect to aluminum carbide (Al4C3), organic contaminations were confirmed to lead to an increased amount of its formation. The carbon-containing refractory material contributed more significantly than organic contaminations on the formation of Al4C3 at melt temperatures over 760 & DEG;C. Formulas were derived based on trial results to enable translation of NMIs PoDFA value [mm(2)/kg] into their mass fraction [ppm] in the melt.Article Citation - WoS: 17Citation - Scopus: 19Strong Coupling of Carbon Quantum Dots in Liquid Crystals(American Chemical Society, 2022) Sarısözen, Sema; Polat, Nahit; Mert Balcı, Fadime; Güvenç, Çetin Meriç; Kocabaş, Çoşkun; Yağlıoğlu, Halime Gül; Balcı, SinanCarbon quantum dots (CDs) have recently received a tremendous amount of interest owing to their attractive optical properties. However, CDs have broad absorption and emission spectra limiting their application ranges. We herein, for the first time, show synthesis of water-soluble red emissive CDs with a very narrow line width (∼75 meV) spectral absorbance and hence demonstrate strong coupling of CDs and plasmon polaritons in liquid crystalline mesophases. The excited state dynamics of CDs has been studied by ultrafast transient absorption spectroscopy, and CDs display very stable and strong photoluminescence emission with a quantum yield of 35.4% and a lifetime of ∼2 ns. More importantly, we compare J-aggregate dyes with CDs in terms of their absorption line width, photostability, and ability to do strong coupling, and we conclude that highly fluorescent CDs have a bright future in the mixed light-matter states for emerging applications in future quantum technologies.Article Citation - WoS: 3Citation - Scopus: 3Atomic-Scale Investigation of the Effect of Surface Carbon Coatings on the Oxidation and Mechanical Properties of Iron Nanowires(Royal Society of Chemistry, 2021) Aral, Gürcan; Islam, Md MahbubulThe understanding of the complex atomistic-scale mechanisms of the oxidation process of carbon (C) coated iron nanowires (Fe NW) and also the resulting modulation of mechanical properties is a highly challenging task. We perform reactive molecular dynamics (RMD) simulations based on the ReaxFF force field to investigate the mechanisms of the oxidation process of [001]-oriented pristine cylindrical Fe NWs with and without a C coating in an O2 environment in order to obtain detailed insights into the influences of the surface C coating on the oxidation process at room temperature. Here, we show that the C-coated shell layer on the free surface of pristine Fe NWs partially controls the spontaneous oxidation when exposed to O2 molecules by hindering the absorption-dissociation of O2 molecules and diffusion of O ions into the shell layer. In particular, the surface modification of the pristine Fe NW with the C-coated shell layer has pronounced effects on the improvement of oxidation resistance by lowering the surface reactivity, which limits the formation of an oxide shell layer on the free surface of the NW. The formation of strong Fe-C bonds in the C-coated shell layer largely restrains the oxidation process. Furthermore, to examine the influence of the C-coated shell layer on the resulting modulation of mechanical properties of the pristine Fe NW, we systematically investigate the mechanical deformation processes and related properties of Fe NW with and without a C coating including their oxidized counterparts subjected to both uniaxial tensile and compressive loads at room temperature. The yield stress and strain (the elastic limit) of Fe NWs including the elastic and plastic deformation phase of the stress-strain relationship are found to be sensitive to the loading modes, the existence of the C-coated shell layer and the resulting formation of an oxide shell layer on the surface of the C-coated Fe NW.Article Citation - WoS: 37Citation - Scopus: 39Reaction of Methyl Radicals With Metal Powders Immersed in Aqueous Solutions(Wiley-VCH Verlag, 2003) Rusonik,I.; Polat,H.; Cohen,H.; Meyerstein,D.Methyl radicals radiolytically produced in aqueous solutions react efficiently with Cr0, Mn0, Fe0, Ni 0, Cu0 and Zn0 powders immersed in the solution. The Cr0, Mn0, Fe0, Ni0 and Zn0 powders reduce the radicals to form methane. On the other hand the Cu0 powder seems to oxidize the radicals. Surprisingly a part of the energy absorbed by the Cr0, Fe0, Ni 0 and Zn0 powders is transferred to the aqueous solution, thus increasing the radical yield. CH4, C2H4, C2H6, C3H6 and C3H 8 are formed when an aqueous deaerated buffer solution, pH 4-5, is added to powders of analytical iron, zinc, manganese and chromium. The source of these gases is carbon traces present, as atoms or atom clusters, in the "analytical" metal powders. These carbon atoms, when present on the surface of the metals, are reduced by the metal particles in aqueous solutions. This mechanism might be the source of light alkanes and alkenes in the prebiotic era. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.Article Citation - Scopus: 15Estimation of the Average Aromatic Cluster Size Based on Solid-State Nmr Measurement of Coal(Japan Institute of Energy, 1999) Kidena, Koh; Murata, Satoru; Artok, Levent; Nomura, MasakatsuMeasurements of solid-state NMR of eight Argonne Premium Coal Samples were conducted to estimate the average aromatic cluster size in these coals. Firstly, the carbon distribution was obtained from SPE/MAS 13C-NMR. Secondary, 1H-CRAMPS NMR spectra gave the hydrogen aromaticity of coal. Combination use of the hydrogen aromaticity and elemental analysis data could afford the amount of tertiary aromatic carbon. The parameter of χ b, the mole fraction of aromatic bridgehead carbons in all aromatic carbons, could be derived from above NMR data and elemental analysis of coal. χ b is directly correlated to the number of aromatic carbon atoms per aromatic cluster, C. In this study, the value of C varied from 10 (corresponding to the size of naphthalene) for Beulah-Zap and Wyodak coals to 23 (corresponding to the size of coronene) for Pocahontas No. 3 coal.