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

Obez hastalarda proinflamatuvar sitokinler ile fibrinolitik sistem arasındaki ilişki

Amaç: Obez kişilerde proinflamatuar sitokinlerden TNF-? ve IL-6, fibrinolitik sistem parametrelerinden t-PA ve PAI-1 ve insülin direnci arasındaki ilişki araştırıldı. Hastalar ve Yöntemler: Çalışmaya obez (VKİ ?30 kg/m2) olarak değerlendirilen 54 kişi (41 kadın, 13 erkek; ort. yaş 33.5) ve obezite sorunu olmayan (VKİ <25 kg/m2) 30 kişi (19 kadın, 11 erkek; ort. yaş 22.3) alındı. Fibrinojen düzeyleri koagülometrik olarak ve TNF-?, IL-6, t-PA, PAI-1 düzeyleri ELISA yöntemiyle ölçüldü. Bulgular: Kontrol grubuyla karşılaştırıldığında, obez kişilerde fibrinojen (p<0.01), PAI-1 (p<0.001), TNF-? (p<0.01) ve IL-6 düzeyleri (p<0.001) anlamlı derecede yüksek, t-PA düzeyi (p<0.001) ve t-PA/PAI-1 oranı (p<0.001) anlamlı derecede düşük bulundu. Obezlerde TNF-? ile t-PA (p=0.007) ve t-PA/PAI-1 oranı (p=0.016) arasında ters ilişki saptandı. İnsülin direnci olan ve olmayan obez kişilerde parametreler arasında fark yoktu. Sonuç: Obezitede adipoz dokudan salgılanan özellikle TNF-? gibi inflamatuar sitokinlerin artması fibrinolizde azalmaya yol açar. Obez kişilerde görülen bu değişiklikler, insülin direncinden bağımsız olarak ateroskleroza neden olabilir.Objectives: The aim of this study was to investigate the relationship between proinflammatory cytokines (TNF-&amp;#945; and IL-6), and fibrinolytic system parameters (t-PA, and PAI-1) and insulin resistance in obese individuals. Patients and Methods: The study included 54 obese subjects (BMI &amp;#8805;30 kg/m2; 41 females, 13 males; mean age 33.5 years) and 30 non-obese healthy individuals (BMI &lt;25 kg/m2; 19 females, 11 males; mean age 22.3 years). Fibrinogen levels were measured by the coagulometric method and the measurements of TNF-&amp;#945;, IL-6, t-PA and PAI-1 were carried out by the ELISA method. Results: Compared with non-obese subjects, obese individuals had significantly higher fibrinogen (p&lt;0.01), PAI-1 (p&lt;0.001), TNF-&amp;#945; (p&lt;0.01), and IL-6 (p&lt;0.001) levels, and significantly lower t-PA level (p&lt;0.001) and t-PA/PAI-1 ratio (p&lt;0.001). We also found an inverse relationship between TNF-&amp;#945; and t-PA levels (p=0.007) and t-PA/PAI-1 ratio (p=0.016) in obese individuals. The presence or absence of insulin resistance did not affect proinflammatory cytokines and fibrinolytic system parameters in obese individuals. Conclusion: Our findings indicate increased inflammatory cytokine levels especially in TNF-&amp;#945; level, and decreased fibrinolysis in obese individuals. These changes may contribute to atherosclerotic process independent from insulin resistance in obesity

Management of Sacral Tumors Requiring Spino-Pelvic Reconstruction with Different Histopathologic Diagnosis: Evaluation with Four Cases

In this retrospective study, surgical results of four patients with sacral tumors having disparate pathologic diagnoses, who were treated with partial or total sacrectomy and lumbopelvic stabilization were abstracted. Two patients were treated with partial sacral resection and two patients were treated with total sacrectomy and spinopelvic fixation. Fixation methods included spinopelvic fixation with rods and screws in two cases, reconstruction plate in one case, and fresh frozen allografts in two cases. Fibular allografts used for reconstruction accelerated bony union and enhanced the stability in two cases. Addition of polymethyl methacrylate in the cavity in the case of a giant cell tumor had a positive stabilizing effect on fixation. As a result, we can conclude that mechanical instability after sacral resection can be stabilized securely with lumbopelvic fixation and polymethyl methacrylate application or addition of fresh frozen allografts between the rods can augment the stability of the reconstruction

3-BOYUTLU UZAYLARDA MODİFİYE ORTOGONAL ÇATIYA GÖRE ADJOINT EĞRİLER

Bu çalışma 6 bölümden oluşmaktadır. Giriş bölümünde çalışmanın amacı ve konunun ele alınma nedeni tartışıldı. Bunun yanı sıra Adjoint eğriler ve modifiye ortogonal çatı üzerine yapılan çalışmalardan bahsedildi. Temel kavramlar bölümünde ise 3-boyutlu Öklid ve Minkowski uzayı, Adjoint eğri ve modifiye ortogonal çatı ile ilgili tanım ve teoremlere yer verildi. Üçüncü bölümde 3-boyutlu Minkowski uzayda bir eğrinin adjoint eğrisi kavramı ele alındı. Dördüncü ve beşinci bölümler çalışmamızın orijinal kısmını oluşturmaktadır. İlk olarak Öklid ve Minkowski uzayında modifiye ortogonal çatı kullanılarak bir eğirinin adjoint eğrisi tanımlandı ve Frenet elemanları arasındaki ilişkiler hesaplandı. Daha sonra torsiyon ile modifiye edilmiş ortogonal çatıya göre adjoint eğri tanımlandı ve bazı karakterizasyonlara yer verildi. Son bölümde ise Mathematica programı kullanılarak örnek eğri çizimleri yapıldı

A STUDY ON THE ELECTRICAL CONDUCTIVITY AND PHASE STABILITY OF THE (Bi2O3)1–x-y (Tm2O3)x (Yb2O3)y DOUBLE–DOPED ELECTROLYTES AT INTERMEDIATE TEMPERATURES

Due to its superior ion conductivity, face–centered cubic–Bi2O3 (δ–phase) material has been recognizedas suitable solid electrolytes in terms of the Intermediate Temperature–Solid Oxide Fuel Cells (IT–SOFCs) applications. Interestingly, the highest conductivity values reported for cubic–stabilized Bi2O3electrolytes have been achieved by employing the double doping approach, relying on co–dopantcontent ratios of 2:1 or 1:2. In the present study, ceramic compositions of Bi2O3 co–doped with Tm–Yb rare earths have been developed using solid–state techniques. For stability of δ–phase, allcompositions were then subjected to heat treatment at 750 °C for 100 hours. Annealed samples werecharacterized by several experimental studies including X–Ray Diffraction (XRD), Termogravimetricand Diffeantial Thermal Analysis (TG &amp; DTA), Four Point Probe Technique (FPPT), And FieldEmission–Scanning Electron Microscope (FE–SEM). The conductivity of sample 8Tm4Yb createdusing a content ratio of 2:1 is 0.432 S/cm at 700 °C, outperforming that of single–doped 20ESBelectrolytes. Arrhenius plots of conductivity in Tm–rich materials also showed that it increased withdoping rate, reflecting an increase in oxygen–unoccupied concentration. In many samples, the order–disorder transitions (ODT) and phase transition (α→δ) were clearly apparent on DTA curves andArrhenius plots. The FE–SEM images of the Tm–rich samples revealed a reduction in particle size with&nbsp;doping, which was directly related to the lattice strain caused by doping. Additionally, surface holeswere visible in FE–SEM images of Tb–rich samples, which could result in a decline in electricalconductivity.Keywords: Phase transition, Ion conductivity, Unit cell contraction, Electrical activation energy,Average crystal size.&nbsp;</p

CHARACTERIZATION OF STRUCTURAL, THERMAL, ELECTRICAL, AND MORPHOLOGICAL PROPERTIES OF BI2O3 ELECTROLYTES CO–DOPED WITH LANTHANIDE OXIDES

Due to their outstanding oxygen ion conductivity, face-centered cubic–Bi2O3 materials (δ-phase) are thought of as a good solid electrolyte selection for low-temperature SOFC applications. When stabilized at room temperature, this highly ion-conducting phase could provide an appropriate replacement to the YSZ electrolytes widely employed in today's SOFC technology. In this study, pure Bi2O3 powders were doped with rare earth oxide powders using a solid–state process under atmospheric circumstances. The XRD patterns indicate that samples A1 (20% doped), A2 (35% doped), and B2 (40% doped) are stabilized with a single cubic phase, and their lattice constants are lower in comparison to the pure phase, as predicted. Due to the absence of endothermic or exothermic peaks in the pattern, DTA curves imply that there is no phase transition. Arrhenius plots demonstrate that increasing the dopant rate has a significant influence on conductivity. Sample B1 (25% doped) exhibits a maximum conductivity of 0.0228 S.cm-1 and an activation energy of 0.86 eV at 750 °C. The grain sizes are not uniform over the surface of the A-series samples, and the grain boundary rapidly changes as the dopant density in the mix increases. Furthermore, the porous structures that appear on the surface as doping increases could be responsible for the notable decrease in conductivity. The EDAX pattern of sample A1 indicated that all components of the mixture were present in the compositions with no unwanted impurities.</p

Adjoint Curve According to Modified Orthogonal Frame with Torsion in 3-Space

The main purpose in this study is to create the adjoint curve of a curve according to the modified orthogonal frame created by torsion in Euclidean and Minkowski 3-space. Besides, it is another purpose to reveal the relationships between the modified orthogonal frame of these curves.In this paper, firstly, the adjoint curve of a space curve in 3D Euclidean space with respect to the modified orthogonal frame formed by torsion is defined and the modified orthogonal frame of the adjoint curve is given by a theorem in terms of the modified orthogonal frame of the main curve.With the help of this theorem, results about properties such as being a general helix and a Salkowski curve between main curve and adjoint curve were given. Similar approaches are discussed for non-null curves in 3D Minkowski space and the adjoint curve of a space curve is defined

FABRICATION AND CHARACTERIZATION OF TB-SM-GD CO-DOPED BI 2 O 3 ELECTROLYTES FOR INTERMEDIATE TEMPERATURES

A high ion conductivity, face-centered cubic δ-Bi2O3 material is regarded as a significant solid electrolyteoption, particularly for low-temperature SOFC applications. Stabilizing this phase while retaining the majorityion conductivity might allow it a competitive advantage in IT-SOFC electrolyte candidacy. It is well acceptedthat δ-Bi2O3 has stronger conductivity than the YSZ electrolytes commonly utilized in HT-SOFC units. Thecurrent work focuses on the structural, thermal, surface, and conductivity properties of Bi2O3 electrolytes co-doped with Tb-Sm-Gd. With the exception of sample 20Tb20Sm20Gd, the XRD outcomes suggest that allsamples are stabilized by cubic δ-phase at room temperature. The computed lattice constants also show unit cellshrinkage, showing that the partial cation substitutions of Bi3+ and lanthanide cations are successful. There areno endothermic or exothermic peaks on the DTA curves, indicating a probable phase transition. ConductivityArrhenius graphs show that conductivity decreases as the dopant ratio increases, suggesting a decrease inpolarization power due to cationic substitution. This study's highest conductivity is 0.131 S/cm for sample10Tb10Sm10Gd, with a total doping rate of 30%. The FE-SEM images clearly point out that doping has asignificant impact on grain size and boundaries. Moreover, the pores on the surface are probably responsible forthe decrease in conductivity resulting from doping. The EDAX pattern of sample 10Tb10Sm10Gd also provesthe combination includes all of the elements, as there are no peaks implying impurities.</div