Browsing by Subject "Iron"

Now showing 1 - 6 of 6

Open Access
Determination of trace element levels in human scalp hair in occupationally exposed subjects by XRF
(Akademiai Kiado Rt., 2001) Dede, Y.; Erten, H. N.; Zararsiz, A.; Efe, N.
Trace element levels in hair of individuals living in urban areas were determined by energy dispersive XRF. Two groups of subjects were investigated, the first group was assumed to be from a healthy environment, the other one was exposed to a high level of contamination due to working conditions. The results were compared to data reported in the literature. The concentrations of Ca, Fe, Cu, Zn and Pb in the scalp hair were determined and the correlation between hair trace element levels and environmental effects was discussed. The results given by the second group show that environmental exposure effects hair trace element levels which are related to body trace element concentrations.
Open Access
The effect of iron on the surface graphitization of silicon carbide
(World Scientific, 2020) Mercan, Elif; Cambaz-Büke, G.
In order to decrease the decomposition temperature of SiC, 12nm Fe thin film is applied on SiC substrates as a catalyst layer using electron beam (e-beam) deposition. To investigate the mechanism of Fe-treated SiC decomposition, local Fe regions are formed through dewetting of the catalyst layer by hydrogen annealing. The results show that Fe decreases the decomposition temperature of SiC effectively and increases the kinetics of the graphitization. Studies showed that depending on the amount of Fe, crumpled and ordered graphene films can be synthesized simultaneously on SiC by using this method.
Open Access
In vivo magnetic resonance imaging of mesenchymal stem cells in myocardial infarction
(Lippincott Williams & Wilkins, 2003) Kraitchman, D. L.; Heldman, A. W.; Atalar, Ergin; Amado, L. C.; Martin, B. J.; Pittenger, M. F.; Hare, J. M.; Bulte, J. W. M.
Background - We investigated the potential of magnetic resonance imaging (MRI) to track magnetically labeled mesenchymal stem cells (MR-MSCs) in a swine myocardial infarction (MI) model. Methods and Results - Adult farm pigs (n=5) were subjected to closed-chest experimental MI. MR-MSCs (2.8 to 16×107 cells) were injected intramyocardially under x-ray fluoroscopy. MRIs were obtained on a 1.5T MR scanner to demonstrate the location of the MR-MSCs and were correlated with histology. Contrast-enhanced MRI demonstrated successful injection in the infarct and serial MSC tracking was demonstrated in two animals. Conclusion - MRI tracking of MSCs is feasible and represents a preferred method for studying the engraftment of MSCs in MI.
Open Access
Induction of triacylglycerol production in Chlamydomonas reinhardtii: comparative analysis of different element regimes
(Elsevier, 2014) Çakmak, Z. E.; Ölmez, T. T.; Çakmak, T.; Menemen, Y.; Tekinay, T.
In this study, impacts of different element absence (nitrogen, sulfur, phosphorus and magnesium) and supplementation (nitrogen and zinc) on element uptake and triacylglycerol production was followed in wild type Chlamydomonas reinhardtii CC-124 strain. Macro- and microelement composition of C. reinhardtii greatly differed under element regimes studied. In particular, heavy metal quotas of the microalgae increased strikingly under zinc supplementation. Growth was suppressed, cell biovolume, carbohydrate, total neutral lipid and triacylglycerol levels increased when microalgae were incubated under these element regimes. Most of the intracellular space was occupied by lipid bodies under all nutrient starvations, as observed by confocal microscopy and transmission electron micrographs. Results suggest that sulfur, magnesium and phosphorus deprivations are superior to nitrogen deprivation for the induction triacylglycerol production in C. reinhardtii. On the other hand, FAME profiles of the nitrogen, sulfur and phosphorus deprived cells were found to meet the requirements of international standards for biodiesel.
Open Access
Preparation, surface state and band structure studies of SrTi (1-X)Fe (x)O (3-δ) (x = 0-1) perovskite-type nano structure by X-ray and ultraviolet photoelectron spectroscopy
(2012) Ghaffari, M.; Shannon, M.; Hui H.; Tan O.K.; Irannejad, A.
In this report, SrTi (1 - x)Fe (x)O (3 - δ) photocatalyst powder was synthesized by a high temperature solid state reaction method. The morphology, crystalline structures of obtained samples, was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM), respectively. The electronic properties and local structure of the perovskite STF x (0 ≤ x ≤ 1) systems have been probed by extended X-ray absorption fine structure (EXAFS) spectroscopy. The effects of iron doping level x (x = 0-1) on the crystal structure and chemical state of the STF x have been investigated by X-ray photoelectron spectroscopy and the valence band edges for electronic band gaps were obtained for STF x by ultraviolet photoelectron spectroscopy (UPS). A single cubic perovskite phase of STF x oxide was successfully obtained at 1200 °C for 24 h by the solid state reaction method. The XPS results showed that the iron present in the STF x perovskite structure is composed of a mixture of Fe 3+ and Fe 4+ (SrTi (1 - x)[Fe 3+, Fe 4+] (x)O (3 - δ)). When the content x of iron doping was increased, the amount of Fe 3+ and Fe 4+ increased significantly and the oxygen lattice decreased on the surface of STF x oxide. The UPS data has confirmed that with more substitution of iron, the position of the valence band decreased. © 2011 Elsevier B.V. All rights reserved.
Open Access
A radiotracer study of the adsorption behavior of aqueous Ba2+ ions on nanoparticles of zero-valent iron
(2007) Çelebi O.; Üzüm, C.; Shahwan, T.; Erten H.N.
Recently, iron nanoparticles are increasingly being tested as adsorbents for various types of organic and inorganic pollutants. In this study, nanoparticles of zero-valent iron (NZVI) synthesized under atmospheric conditions were employed for the removal of Ba2+ ions in a concentration range 10-3 to 10-6 M. Throughout the study, 133Ba was used as a tracer to study the effects of time, concentration, and temperature. The obtained data was analyzed using various kinetic models and adsorption isotherms. Pseudo-second-order kinetics and Dubinin-Radushkevich isotherm model provided the best correlation with the obtained data. Observed thermodynamic parameters showed that the process is exothermic and hence enthalpy-driven. © 2007 Elsevier B.V. All rights reserved.