Kazaz I.,Erzurum Technical University
Earthquake and Structures | Year: 2016
A parametric study was conducted to investigate the seismic deformation demands in terms of drift ratio, plastic base rotation and compression strain on rectangular wall members in frame-wall systems. The wall index defined as ratio of total wall area to the floor plan area was kept as variable in frame-wall models and its relation with the seismic demand at the base of the wall was investigated. The wall indexes of analyzed models are in the range of 0.2-2%. 4, 8 and 12-story frame-wall models were created. The seismic behavior of frame-wall models were calculated using nonlinear time-history analysis and design spectrum matched ground motion set. Analyses results revealed that the increased wall index led to significant reduction in the top and inter-story displacement demands especially for 4-story models. The calculated average inter-story drift decreased from 1.5% to 0.5% for 4-story models. The average drift ratio in 8- and 12-story models has changed from approximately 1.5% to 0.75%. As the wall index increases, the dispersion in the calculated drifts due to ground motion variability decreased considerably. This is mainly due to increase in the lateral stiffness of models that leads their fundamental period of vibration to fall into zone of the response spectra that has smaller dispersion for scaled ground motion data set. When walls were assessed according to plastic rotation limits defined in ASCE/SEI 41, it was seen that the walls in frame-wall systems with low wall index in the range of 0.2-0.6% could seldom survive the design earthquake without major damage. Concrete compressive strains calculated in all frame-wall structures were much higher than the limit allowed for design, εc=0.0035, so confinement is required at the boundaries. For rectangular walls above the wall index value of 1.0% nearly all walls assure at least life safety (LS) performance criteria. It is proposed that in the design of dual systems where frames and walls are connected by link and transverse beams, the minimum value of wall index should be greater than 0.6%, in order to prevent excessive damage to wall members. © 2016 Techno-Press, Ltd.
Turgut G.,Erzurum Technical University |
Turgut G.,Ataturk University
Philosophical Magazine | Year: 2015
In the present work, an investigation study on the crystal structure, surface morphology, electrical conductivity and optical transparency of spray-deposited Pr-doped SnO2 was made as a function of Pr doping content. The X-ray diffraction studies indicated that the films were grown at the (2 1 1) preferential orientation. The values of crystallite size and strain were determined using Williamson-Hall method and they varied between 71.47 and 208.76 nm, and 1.98 × 10-3 - 2.78 × 10-3. As seen from Scanning Electron Microscope micrographs, the films were composed of homogenous dispersed pyramidal-shaped grains. The n-type conductivity of films was confirmed with Hall Effect measurements, and the best electrical parameters were found for 3 at.% Pr doping level. The highest optical band gap and transmittance values were observed for undoped SnO2 sample. The highest figure of merit (Φ), which is a significant parameter to interpret the usage efficiency of conductive and transparent materials in the optoelectronic and solar cell applications, was calculated to be 2.85 × 10-5 ω-1 for 1 at.% Pr doping content. As a result of this study, it may be concluded that Pr-doped SnO2 films with above properties can be used as a transparent conductor in various optoelectronic applications. © 2015 Taylor & Francis.
Turkez H.,Erzurum Technical University |
Geyikoglu F.,Ataturk University |
Tatar A.,Ataturk University
Toxicology and Industrial Health | Year: 2013
This study was carried out to evaluate the protective role of borax (BX) on genotoxicity induced by aluminum (Al) in rat liver, using liver micronucleus assay as an indicator of genotoxicity. Sprague-Dawley rats were randomly separated into six groups and each group had four animals. Aluminum chloride (AlCl3; 5 mg/kg b.w.) and BX (3.25 and 13 mg/kg b.w.) were injected intraperitoneally to rats. Besides, animals were also treated with Al for 4 consecutive days followed by BX for 10 days. Rats were anesthetized after Al and BX injections and the hepatocytes were isolated for counting the number of micronucleated hepatocytes (MNHEPs). AlCl3 was found to significantly (p < 0.05) increase the number of MNHEPs. Rats treated with BX, however, showed no increase in MNHEPs. Moreover, simultaneous treatments with BX significantly modulated the genotoxic effects of AlCl3 in rats. It can be concluded that BX has beneficial influences and has the ability to antagonize Al toxicity. © The Author(s) 2012.
Aydin E.,Ataturk University |
Turkez H.,Erzurum Technical University |
Keles M.S.,Ataturk University
Cytotechnology | Year: 2014
Carvacrol (CVC) is a phenolic monoterpene present in many essential oils of medicinal and aromatic plants and has attracted attention because of its beneficial biological activities. To date, although various biological activities of CVC have been demonstrated, its neurotoxicity on cultured primary rat neurons and N2a neuroblastoma cells has never been explored. Therefore, in this present study, we aimed to describe in vitro antiproliferative and/or cytotoxic properties (by 3-(4,5 dimetylthiazol -2-yl)-2,5 diphenlytetrazolium bromide (MTT) test), genotoxic damage potentials (by single cell gel electrophoresis (SCGE) or Comet assay) and antioxidant activities (by total antioxidant capacity (TAC) and total oxidative stress (TOS) analysis) of CVC in vitro. Dose (0-400 mg/L) dependent effects of CVC were tested on both cultured primary rat neurons and N2a neuroblastoma cells. Statistical analysis of MTT assay results indicated significant (p < 0.05) decreases of cell proliferation rates in both cell types treated with CVC at 200 and 400 mg/L. On the other hand, the mean values of the total scores of cells showing DNA damage (for comet assay) was not found significantly different from the control values for both cells (p > 0.05). In addition, our results indicated that 10, 25 and 50 mg/L of CVC treatment caused increases of TAC levels in cultured primary rat neurons but not in the N2a cell line. However, CVC treatments led to increases of TOS levels in cultured primary rat neurons at only 400 mg/L while they led to increases of TOS levels in N2a neuroblastoma cells at 200 and 400 mg/L. The present findings demonstrated that CVC could be a source of antioxidant and chemopreventive activities to be studied on cancer diseases. © 2013 Springer Science+Business Media Dordrecht.
Yildiz F.,Erzurum Technical University
High Temperature Materials and Processes | Year: 2014
In this study, conventional WC-12Co cermet coatings were deposited on AZ91 magnesium alloy using High Velocity Oxy-Fuel spray method. The effects of different coating thicknesses (60 and 120 μm) and wear loads (20 and 30 N) on tribological properties of AZ91 magnesium alloy coated with WC-12Co were investigated. Structural, mechanical and tribological properties of WC-12Co coatings were analyzed by means of X-ray diffractometer, scanning electron microscope, micro-hardness tester and pin-on-disc tribotester. It was observed that WC-12Co coating is an effective method for improving the wear behavior of AZ91 magnesium alloy. © 2014 by Walter de Gruyter Berlin/Boston 2014.