First-principles calculations to investigate the structural, electronic, elastic, vibrational and thermodynamic properties of the full-Heusler alloys X2ScGa (X = Ir and Rh)

This study has investigated ab initio pseudopotential calculations on the structural, electronic, elastic, vibrational and thermodynamic properties of the full-Heusler X2ScGa (X = Ir and Rh) alloys. The calculations have taken place under consideration of the generalized gradient approximation (GGA) of the density functional theory (DFT) with using the plane-wave ab initio pseudopotential method. According to the calculations, the major contribution to electronic states at the Fermi energy has been achieved by d orbitals, revealing a more active role for transition metals Ir (Rh) and Sc atoms. The reckonings point out that the Ir2ScGa and Rh2ScGa have metallic behavior at the equilibrium lattice constant with the density of states (DOS) at the Fermi level (N (EF)) of 1.412 states/eV and 1.821 states/eV, respectively. The results of the elastic constants showed that these compounds met the criteria for Born mechanical stability. It was also observed that they have a ductile structure and exhibit anisotropic behavior according to Pugh criteria. Besides, the full phonon spectra and their projected partial density of states of the alloys have been analyzed with the first-principle linear-response approach of the density-functional perturbation theory. All the alloys behaved dynamically stable in the L21 phase. Furthermore, internal free energy, entropy, specific heat capacity at constant volume and vibrational free energy changes of Ir2ScGa and Rh2ScGa alloys were analyzed and discussed between the temperature range of 0–800 K using the quasi harmonic approximation. According to the results, these alloys are potential candidate for industrial use. © 2020 Elsevier Lt

Mechanical Properties of Polypropylene (PP) + High-density Polyethylene (HDPE) Binary Blends

In this study, the mechanical properties and non-isothermal degradation kinetics of polypropylene (PP), high-density polyethylene (HDPE) with dilauroyl peroxide and their blends in different mixture ratios were investigated. the effects of adding dilauroyl peroxide (0-0.20 wt%) on the mechanical and thermal properties of PP + HDPE blends have been studied. on the other hand, the kinetics of the thermal degradation and thermal oxidative degradation of PP + HDPE (80/20 wt%) blends were studied in different atmospheres, to analyze their thermal stability. the kinetic and thermodynamic parameters such as the activation energy, Ea, the pre-exponential factor, A, the reaction order, n, the entropy change, the enthalpy change, and the free energies of activated complex related to PP, HDPE, and blend systems were calculated by means of the several methods on the basis of the single heating rate. a computer program was developed for automatically processing the data to estimate the reaction parameters by using different models. Most appropriate method was determined for each decomposition step according to the least-squares linear regression. Copyright © 2013 John Wiley & Sons, Ltd

Determination of Irrigation Areas Using Discriminate Analysis in Terms of Some Water Parameters

Bu çalışma Kırşehir ilinde sulama yapılan tarım alanlarında yapılmıştır. Bunun için, sulama yapılan alanlardan rastgele seçilen 40 noktadaki su kaynağından üç tekrarlamalı olarak alınan toplam 120 örnek üzerinde analizler yapılmıştır. Su örneklerinde pH, sülfat, iletkenlik ve organik madde tayini yapıl mıştır. Elde edilen veriler su kaynaklarına göre değişkenler arasında ilişkinin olup olmadığının belirlenmesi için yapılan Pearson korelasyon analiz sonuçlarına bakılmış daha sonra ayırma (discriminant) analizi ile pH, sülfat, iletkenl i k ve organik maddede benzerlik gösteren kaynaklar ayrılmıştır. Sonuç olarak, pH ile iletkenlik arasında (r=- 0,394**) ve yine pH ile sülfat miktarı arasında ters yönlü ancak önemli (r=-0,344**) ilişkiler bulunmuştur. Ayrıca ayırma analizi sonucunda pH üç gruba, sülfat ve iletkenlik dört gruba ve organik madde ise beş gruba ayrılmıştır.This study was carried out in irrigated agricultural areas in Kırşehir province. To do this, analyzes were made on a total of 120 specimens taken from three randomly chosen water sources at randomly chosen sites from the irrigated areas. PH, sulphate, conductivity and organic matter were determined in water samples. Pearson correlation analysis results were used to determine whether there was a relationship between the variables according to the obtained water resources. Then, by means of discriminant analysis, sources showi ng similarities in pH, sulfate, conductivity and organic matter were separated. As a result, between pH and conductivity (r = -0,394 **) and again between pH and sulphate amount, but significant (r = -0,344 **) relations were found. In addition, as a result of the separation analysis, the pH was divided into three groups, the sulfate and conductivity groups were four groups and the organic matter was divided into five groups