Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 1Citation - Scopus: 2Reactive Wetting of Metallic/Ceramic (al/Α-al2 O3 ) Systems: a Parallel Molecular Dynamics Simulation Study(TÜBİTAK - Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, 2020) Aral, GürcanThe reactive wetting process of a flat solid alumina (?-Al2 O3) ceramic surface by metallic aluminum (Al) nanodroplets with different shapes (spherical, cylindrical, and layer) is studied using parallel molecular dynamics (MD) simulations based on a variable charge MD method, with focuses on heat transfer, mass transfer, and the structure of the reactive region at the Al/?-Al2 O3 interface. We find that the diffusion of oxygen (O) atoms from the substrate into the droplet leads to the formation of a continuous layer of reaction product at the interface. The diffusion length of oxygen atoms into the spherical Al droplet is found to be ~7.3 Å, and the number density of O atoms at the ~5 top layers of the substrate decreases substantially. As a result, the structural correlations near the reactive region differ considerably from those in the solid substrate. Heat generated by the exothermic reactions in the reactive region is transferred to both the substrate and the droplet. The heat transfer is found to be sensitive to droplet shape.Article Citation - WoS: 21Citation - Scopus: 27Effect of High Aluminum Concentration in Water Resources on Human Health, Case Study: Biga Peninsula, Northwest Part of Turkey(Springer Verlag, 2010) Bakar, Coşkun; Özışık Karaman, Handan Işın; Baba, Alper; Şengünalp, FatmaWidespread and intense zones of silicified, propylitic, and argillic alteration exist as outcrop around the Biga Peninsula, NW Turkey. Most of the springs in the study area surface out from these altered volcanic rocks. The concentrations of aluminum (Al) in these springs ranged from 13.17 to 15.70 ppm in this region. These high levels of Al were found to exceed the maximum allowable limits (0.2 ppm) depicted in national and international standards of drinking water quality. Therefore, the effect of high Al in water resources on human health was evaluated in this research. A total of 273 people aged above 18 years and living in the Kirazli region (whose water supply is from springs emerging from these alteration zones) and in the Ciplak-Halileli region (whose water supply is provided from an alluvium aquifer) were selected as the research group. For this group, a questionnaire was completed that contained questions on descriptive characteristics of humans and a Mini-Mental State Examination (MMSE) was administered by the authors using the face-to-face interview technique. A neurological examination was then performed by the neurology specialist as a second-stage investigation. Finally, 10 ml of venous blood samples were obtained from these people as a third-stage analysis to determine the serum Al levels together with vitamin B12, folic acid, and thyroid-stimulating hormone parameters. The result typically revealed that the MMSE score was less in 31.9% and there was no statistically significant difference between the two regions. However, the result also showed that neuropathy in the history (including a careful past medical history) was significantly higher in the Kirazli region. © 2009 Springer Science+Business Media, LLC.Article Citation - WoS: 11Citation - Scopus: 15Effects of Humic Acid on Root Development and Nutrient Uptake of Vicia Faba L. (broad Bean) Seedlings Grown Under Aluminum Toxicity(Taylor and Francis Ltd., 2015) Büyükkeskin, Tamer; Akıncı, Şener; Eroğlu, Ahmet EminInteractions of humic acid with development and uptake by seedlings of Vicia faba L., (cv. Eresen 87) grown in conditions of aluminium toxicity have been investigated in pot experiments in a controlled greenhouse environment. The objective of the study was to investigate whether humic acid moderates aluminum toxicity. The seedlings were treated with solutions of aluminum chloride (AlCl3) prepared in Hoagland control nutrient solution (HO) and 50 and100 μM and humic acid + Hoagland (HA) solutions, respectively. The 50 and100 μM HA solutions increased root fresh (RFW) and dry (RDW) weights, where the RFW differed significantly from controls (HO) after statistical evaluation by NCSS (NCSS, Kaysville, Utah) with two-sample T-test range at the 5% level. The results of the current experiment suggested that humic acid had suppressed or counteracted the toxic effect of aluminum (Al3+) on both main and lateral root growth. Humic acid seems to block the effect of Al3+ on nutrient uptake, as tested by atomic absorption spectrophotometry (AAS) and flame photometery (FP). Al3+ content in the roots was significantly decreased by 219% in 50-μM HA and by 49% in 100-μM HA treatments respectively. Potassium (K+), sodium (Na+), and iron (Fe3+) were recorded as the other elements taken up in the greatest amounts among the tested nutrients, in addition to Al3+. Humic acid increased the contents of Na+, K+, manganese (Mn2+), and zinc (Zn2+) significantly in both concentrations of HA treatment compared to controls. The Fe3+ content in the roots decreased, in both treatments of HA, application by 252% and 32% respectively. The reduction in the former was significant.Article Citation - WoS: 32Citation - Scopus: 35Liquid Phase Transformation of ?-Pinene Over Beta Zeolites Containing Aluminium or Boron, Titanium and Vanadium as Lattice Ions(Elsevier Ltd., 2005) Gündüz, Gönül; Dimitrova, Raina D.; Yılmaz, Selahattin; Dimitrov, LjubomirBeta zeolites with different modules (SiO2/Al2 O3) and containing B, Ti or V in lattice positions were synthesised by different methods and tested as catalysts in liquid phase transformation of α-pinene at 100 °C in a batch reactor. It was established that the hydrogen forms of Beta samples with a SiO2/Al2O3 module of about 55-66 and containing both micro- and mesopores displayed high catalytic activity in liquid phase isomerization of α-pinene. Samples with boron, titanium or vanadium, as lattice ions possess insignificant catalytic activity.Article Citation - WoS: 67Citation - Scopus: 82Microhardness and Fracture Toughness of Dental Materials by Indentation Method(John Wiley and Sons Inc., 2005) Şakar-Deliormanlı, Aylin; Şakar Deliormanlı, Aylin Müyesser; Güden, Mustafa; Güden, MustafaThe main objective of this study was to measure the fracture toughness of the human teeth enamel using the microindentation technique and to compare the results calculated from the equations developed for Palmqvist and radial-median cracks. Vickers microhardness measurements of dental ceramic (alumina) and human teeth were performed using indentation fracture method. The fracture toughness of enamel was calculated using different equations reported in the literature. Vickers microhardness of the sintered alumina specimen (98.8% theoretical density) was measured to be 14.92 GPa under 9.8N indentation load. Three equations based on the radial-median cracks were found to be applicable for the fracture toughness determination of the enamel. Results show that indentation fracture method is adequate to measure microhardness and fracture toughness of dental materials. However the calculation of fracture toughness depended on the nature of the cracks and also on the location of the indentation. Therefore, it is necessary to identify the crack profile and to select the appropriate equation for accurate fracture toughness values.