Browsing by Author "Vurdu C.D."

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Effect of Ni Addition on the Morphology and Microstructure of Both Conventional Cast and Melt-Spun of Al–Si–Fe–Nb (at wt%) Alloy
(2019-11-01) Kilicaslan M.F.; Altaib S.S.; Vurdu C.D.
In this project the morphology and microstructure of both conventional cast and melt spun of Al–20Si–9Fe–1.2Nb and Al–20Si–9Fe–1.2Nb–6Ni (at wt%) alloys were investigated. Therefore, in order to study the effect of added Ni on the morphology characteristics of the above-mentioned alloy, the resulting conventional cast and ribbons of Al–20Si–9Fe–1.2Nb and Al–20Si–9Fe–1.2Nb–6Ni alloys were synthesized and analysed using OM optical microscopy, X-ray diffraction, SEM scanning electron microscopy together with EDS energy dispersive spectroscopy. Observations exhibit that, XRD patterns of Al–Si–Fe–Nb and Al–Si–Fe–Nb–Ni ribbons revealed the peaks of only α-Al phase. Therefore, after adding of 6 wt% Ni, peaks of α-Al were shifted to the relatively lower angles with a very weak intensity. Furthermore, 6 wt% Ni addition causes homogeneously scattered colonies (size range 5 –25 μm) which contain fine spherical (primary Si and δ-Al4(FeNiNb)Si2 phases) particles in the α-Al dendrite of rapidly solidified Al–20Si–9Fe–1.2Nb alloy, the size of spherical particles were found to be in the range of 100 nm–1 μm.
Electronic-topological and neural network approaches to the structure-antimycobacterial activity relationships study on hydrazones derivatives
(2015-01-01) Kandemirli F.; Vurdu C.D.; Başaran M.A.; Sayiner H.S.; Shvets N.; Dimoglo A.; Kovalish V.; Polat T.
That the implementation of Electronic-Topological Method and a variant of Feed Forward Neural Network (FFNN) called as the Associative Neural Network are applied to the compounds of Hydrazones derivatives have been employed in order to construct model which can be used in the prediction of antituberculosis activity. The supervised learning has been performed using (ASNN) and categorized correctly 84.4% of them, namely, 38 out of 45. Ph1 pharmacophore and Ph2 pharmacophore consisting of 6 and 7 atoms, respectively were found. Anti-pharmacophore features socalled "break of activity" have also been revealed, which means that APh1 is found in 22 inactive molecules. Statistical analyses have been carried out by using the descriptors, such as EHOMO, ELUMO, ΔE, hardness, softness, chemical potential, electrophilicity index, exact polarizibility, total of electronic and zero point energies, dipole moment as independent variables in order to account for the dependent variable called inhibition efficiency. Observing several complexities, namely, linearity, nonlinearity and multi-co linearity at the same time leads data to be modeled using two different techniques called multiple regression and Artificial Neural Networks (ANNs) after computing correlations among descriptors in order to compute QSAR. Computations resulting in determining some compounds with relatively high values of inhibition are presented.
H(D) → D(H) + Cu(111) collision system: Molecular dynamics study of surface temperature effects
(2011-04-28) Vurdu C.D.; Gven Z.B.
All the channels of the reaction dynamics of gas-phase H (or D) atoms with D (or H) atoms adsorbed onto a Cu(111) surface have been studied by quasiclassical constant energy molecular dynamics simulations. The surface is flexible and is prepared at different temperature values, such as 30 K, 94 K, and 160 K. The adsorbates were distributed randomly on the surface to create 0.18 ML, 0.28 ML, and 0.50 ML of coverages. The multi-layer slab is mimicked by a many-body embedded-atom potential energy function. The slab atoms can move according to the exerted external forces. Treating the slab atoms non-rigid has an important effect on the dynamics of the projectile atom and adsorbates. Significant energy transfer from the projectile atom to the surface lattice atoms takes place especially during the first impact that modifies significantly the details of the dynamics of the collisions. Effects of the different temperatures of the slab are investigated in this study. Interaction between the surface atoms and the adsorbates is modeled by a modified London-Eyring- Polanyi-Sato (LEPS) function. The LEPS parameters are determined by using the total energy values which were calculated by a density functional theory and a generalized gradient approximation for an exchange-correlation energy for many different orientations, and locations of one- and two-hydrogen atoms on the Cu(111) surface. The rms value of the fitting procedure is about 0.16 eV. Many different channels of the processes on the surface have been examined, such as inelastic reflection of the incident hydrogen, subsurface penetration of the incident projectile and adsorbates, sticking of the incident atom on the surface. In addition, hot-atom and Eley-Rideal direct processes are investigated. The hot-atom process is found to be more significant than the Eley-Rideal process. Furthermore, the rate of subsurface penetration is larger than the sticking rate on the surface. In addition, these results are compared and analyzed as a function of the surface temperatures. © 2011 American Institute of Physics.
Reaction mechanisms of H(D) → D(H) + Pt(111) interaction system: Quasiclassical molecular dynamics simulations
(2021-04-01) Vurdu C.D.
Reaction mechanisms of the H(or D) → D(or H) + Pt(111) interaction system have been proposed by using quasiclassical molecular dynamics simulations. First, the adsorbate atoms are dispersed randomly over the surface’s adsorption sites to form 0.18 ML, 0.25 ML, and 0.50 ML of coverages. Since the surface is considered to be resilient, thanks to imitating the multi-layer slab by using a function of many-body embedded-atom potential energy, the slab atoms can move because of the implemented external forces. Thus, energy transfer from the incident atom to surface atoms and adsorbates has been considered a real collision system. Moreover, the London-Eyring-Polanyi-Sato function is modified to model interaction between the adsorbates and slab atoms. In addition to desorption of HD and H2(or D2) after the collision of the incoming H(or D) atom with the surface, subsurface penetration, sticking on the surface, and inelastic reflection of the incident atom have been investigated in detail as the reaction mechanisms on the surface. In addition, isotopic effects on reaction mechanisms have been analyzed in depth and shown. Also, hot-atom and Eley-Rideal mechanisms have been examined and explained. The hot-atom mechanism is responsible for the formation of H2/D2 products. Furthermore, the sticking rate on the surface is lower than the rate of subsurface penetration.
Reaction mechanisms of H(D) → D(H) + Pt(111) interaction system: Quasiclassical molecular dynamics simulations
(2021-04-01) Vurdu C.D.; Vurdu, CD
Reaction mechanisms of the H(or D) → D(or H) + Pt(111) interaction system have been proposed by using quasiclassical molecular dynamics simulations. First, the adsorbate atoms are dispersed randomly over the surface’s adsorption sites to form 0.18 ML, 0.25 ML, and 0.50 ML of coverages. Since the surface is considered to be resilient, thanks to imitating the multi-layer slab by using a function of many-body embedded-atom potential energy, the slab atoms can move because of the implemented external forces. Thus, energy transfer from the incident atom to surface atoms and adsorbates has been considered a real collision system. Moreover, the London-Eyring-Polanyi-Sato function is modified to model interaction between the adsorbates and slab atoms. In addition to desorption of HD and H2(or D2) after the collision of the incoming H(or D) atom with the surface, subsurface penetration, sticking on the surface, and inelastic reflection of the incident atom have been investigated in detail as the reaction mechanisms on the surface. In addition, isotopic effects on reaction mechanisms have been analyzed in depth and shown. Also, hot-atom and Eley-Rideal mechanisms have been examined and explained. The hot-atom mechanism is responsible for the formation of H2/D2 products. Furthermore, the sticking rate on the surface is lower than the rate of subsurface penetration.
Synthesis and quantum chemical calculations of 4-(2-Fluorophenyl)-1-(2- oxoindolin-3-ylidene)thiosemicarbazone and its Zinc(II) Complex
(2013-01-01) Kandemirli F.; Akkaya Y.; Vurdu C.D.
In this study, wavenumbers, IR intensities and molecular parameters of 4-(2-fluorophenyl)-1-(2-oxoindolin-3-ylidene)thiosemicarbazone (I2FPTH2) and its zinc(II) complex have been studied theoretically by using the ab initio Hartree-Fock (HF) method with the 3-21G, 3- 21G, 6-31G(d,p), 6-311G (d,p), 6-311++G (d,p) and 6-311++G (2d,2p) basis sets. In addition to theoretical study,they have been prepared for characterization of structure by means of elemental analyses which are FT-IR, electronic and 1H NMR Zn(II) complex spectra. Moreover, according to the results of Fukui functions values of I2FPTH2, calculated with B3LYP/6-31G(d,p) and B3LYP/6- 311G(d,p), the contribution of sulphur to the HOMO is found predominant 47.69 and 49.16 %, respectively while the contribution of nitrogen to the LUMO is also found dominant as 24.82 and 24.21 %, respectively. The theoretical results of wavelengths, 1H and 13C NMR for wavenumbers are sensibly consistent with the results of experimental study.
The quantum chemical calculations of serine, therionine and glutamine
(2014-01-01) Kandemirli F.; Saracoglu M.; Amin M.A.; Basaran M.A.; Vurdu C.D.
An examination of quantum chemical and corrosion inhibition studies for three serine (Ser), therionine (Thr) and glutamine (Glu) which had been tested as corrosion safe inhibitors for cold rolled steel (CRS) in 1.0 M HCl solutions at different temperatures (283-333 K) were made to see if any clear links exist between them. The Genetic Function Approximation Method has been used for QSAR study. The correlation between inhibition efficiency and descriptor variables obtained from the quantum chemical calculation using B3LYP/6-311G(d,p), B3LYP/6-311++G(2d,2p), MP2/6-311G(d,p), and CBS-APNO methods. © 2014 The Authors.