Browsing by Subject "Copper"

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Open Access
Compound Hertzian chain model for copper-carbon nanocomposites' absorption spectrum
(2011) Kokabi, A.; Hosseini, M.; Saeedi, S.; Moftakharzadeh, A.; Vesaghi, M.A.; Fardmanesh, M.
The infrared range optical absorption mechanism of carbon-copper composite thin layer coated on the diamond-like carbon buffer layer has been investigated. By consideration of weak interactions between copper nanoparticles in their network, optical absorption is modelled using their coherent dipole behaviour induced by the electromagnetic radiation. The copper nanoparticles in the bulk of carbon are assumed as a chain of plasmonic dipoles, which have coupling resonance. Considering nearest neighbour interactions for this metallic nanoparticles, surface plasmon resonance frequency (ω 0) and coupled plasmon resonance frequency (ω 1) have been computed. The damping rate against wavelength is derived, which leads to the derivation of the optical absorption spectrum in terms of ω 0 and ω 1. The dependency of the absorption peaks to the particle size and the particle mean spacing is also investigated. The absorption spectrum is measured for different Cu-C thin films with various Cu particle size and spacing. The experimental results of absorption are compared with the obtained analytical ones. © 2011 The Institution of Engineering and Technology.
Open Access
Determination of Plasma Temperature of Copper Vapour laser
(Cambridge University Press, 2016) Namnabat, M.; Behrouzinia, S.; Moradi, A. R.; Khorasani, K.
The output power and the temperature profile of a copper vapour laser were investigated versus frequency with various kinds of back mirror in its resonator cavity. A semi-experimental method was used for measuring the plasma temperature and obtaining the temperature profile with various back mirrors. The obtained plasma temperature through this method has good agreement with the operational temperature of the laser.
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
Effect of six weeks aerobic training upon blood trace metals levels
(2006) Savaş, S.; Şenel, Ö.; Çelikkan, H.; Uǧraş, A.; Aksu, M. L.
This study was carried out to investigate the effects of 6-week aerobic exercise program upon blood Zn and Cu levels. There were 12 male university students with an average age of 21.67+/-0.89 years and no regular training habits participated in the study. The participants were subjected three days a week 1 hour a day continuous running program on treadmill with an intensity of 60-70% for a period of six weeks. They were fed with zinc and copper free diet throughout the study and it was made sure that they were not using copper or zinc containing vitamin tablets. The difference between the pre and post study period were found to be statistically significant as regards to both resting and maximal loading conditions (p<0.01). The pre and post training maxVO2 values were also found to be positively correlated with the copper and zinc levels in blood. Both the copper and zinc blood levels were found decreased after the training period p<0.05.
Open Access
Ein kupferzeitlicher dolch im eisenzeitlichen Italien – die notwendige Revision einer „sardischen" Stichwaffe aus dem depotfund von San Franscesco, Bologna
(Roemisch-Germanisches Zentralmuseum * Forschungsinstitut fuer Vor- und Fruehgeschichte, 2007) Zimmermann, T.
This short contribution is a chronological and typological reassessment of a fragmented tanged and riveted dagger belonging to the famous Bologna-San Francesco metal hoard, found in 1877, with the majority of associated artefacts dated to the European Iron Age. This critical reappraisal suggests that this dagger, commonly identified as of Iron Age »Sardinian« type, belongs to a totally different period and culture: It bears all formal and technical details significant for the so-called »Malé Leváre« group of Copper Age daggers from East-/Southeast Europe and the Balkans, commonly dated to the midth of the 4th millennium B.C. Since this hoard contains several other items already identified as of pre-Iron Age date, one more object can now be associated with this group, thereby increasing the overall number of this relatively rare Copper Age stabbing weapon.
Open Access
Enhanced angiogenic effects of RGD, GHK peptides and copper (II) compositions in synthetic cryogel ECM model
(Elsevier, 2020) Zoughaib, M.; Luong, D.; Garifullin, Ruslan; Gatina, D. Z.; Fedosimova, S. V.; Abdullin, T. I.
Synthetic oligopeptides are a promising alternative to natural full-length growth factors and extracellular matrix (ECM) proteins in tissue regeneration and therapeutic angiogenesis applications. In this work, angiogenic properties of dual and triple compositions containing RGD, GHK peptides and copper (II) ions (Cu2+) were for the first time studied. To reveal specific in vitro effects of these compositions in three-dimensional scaffold, adamantyl group bearing peptides, namely Ada-Ahx-GGRGD (1) and Ada-Ahx-GGGHK (2), were effectively immobilized in bioinert pHEMA macroporous cryogel via host-guest β-cyclodextrin-adamantane interaction. The cryogels were additionally functionalized with Cu2+ via the formation of GHK-Cu complex. Angiogenic responses of HUVECs grown within the cryogel ECM model were analyzed. The results demonstrate that the combination of RGD with GHK and further with Cu2+ dramatically increases cell proliferation, differentiation, and production of a series of angiogenesis related cytokines and growth factors. Furthermore, the level of glutathione, a key cellular antioxidant and redox regulator, was altered in relation to the angiogenic effects. These results are of particular interest for establishing the role of multiple peptide signals on regeneration related processes and for developing improved tissue engineering materials.
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Ergani Bakır Fabrikası ve Maden ilçesi
(Bilkent University, 2023) Barça, Elif; Özer, Kansav; Yakın, Melih Can; Özkan, Semih Kaan; Bilen, Zehra
This article examines all aspects of the Ergani Copper Factory, which operated from 1939 to 1994. The establishment of the factory, the financial and social opportunities provided to the factory employees, the impact of the factory on the district's sociocultural structure, its contributions to the Turkish economy, and the fate of the Maden town following its closure will all be looked at respectively. Maaz Doğan and Celal Şengün, former employees of the factory, were interviewed to add uniqueness to the research. Dozens of articles, state archives and newspaper articles on the subject were examined and compared with interviews. All of the research led to the creation of an essay that covers every aspect of the town and the factory.
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
Low-amplitude, force gradient imaging of Cu(100) surface using tunnel current feedback
(Institute of Physics Publishing, 2004) Özer, H. Ö.; Norris, A.; Oral, A.; Hoffmann, P. M.; Pethica, J. B.
The large corrugation amplitudes in scanning tunnelling microscope (STM) images of metal surfaces have been commonly attributed to the action of forces between the tip and the sample. We have investigated the Cu(100) surface using a high-resolution non-contact atomic force microscope/scanning tunnelling microscope (nc-AFM/STM) in UHV. Force gradient and STM topography images were acquired simultaneously using constant tunnelling current feedback. Force gradient images showed atomic resolution whereas STM scans exhibited almost no contrast, corresponding to a flat tip trajectory during scans. The corrugation height in force gradient images was found to increase as the set tunnelling current was increased. Force gradient and tunnel current were directly measured as a function of separation, to determine the operating conditions during imaging. The STM operation regime is found to lie between the minimum of the stiffness curve and the start of repulsive force.
Open Access
Microstructural association between mechanical behavior with bending fracture surfaces in Astaloy CrA sintered parts alloyed by Cu and C
(Elsevier Ltd, 2014) Khorsand H.; Ghaffari, M.; Ganjeh, E.
Application of powder metallurgy technique, a method presenting both economic and technical concepts for producing sintered parts, has been expanding in automobile and other engineering industries. Powder metallurgy parts usually possess residual porosity in their microstructures deteriorating mechanical performance. There have been many solutions to increasing of strength in these parts such as applying different heat treatment or adding alloying elements. It is well known that Fe-Cu-C is the one of main alloying system for both increasing the strength and decreasing cost of them. In this study, the microstructure, mechanical properties (transverse rapture strength and hardness), crack behavior and fracture modes of a low alloy Fe-Cr powder (Astaloy CrA) with different amount of copper (0, 1 and 2. wt.%) and carbon, in form of graphite (0.45, 0.6 and 0.8. wt.%) sintered at conventional condition have been investigated. Microstructural evolution showed adding copper and graphite as alloying elements could generate widespread of strength (857-1380. MPa) and hardness (170-295 HV5). Developing different phases in microstructure was the main reason for various mechanical properties. Crack coalescence phenomenon leads to fracturing with ductile (at sinter-necks) and brittle morphology. Micro-mechanism of fracture related to transparticle and interparticle crack propagation. © 2013 Elsevier Ltd.
Open Access
Near-Infrared-Emitting five-monolayer thick copper-doped CdSe nanoplatelets
(WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2019) Sharma, Ashma; Sharma, Manoj; Güngör, Kıvanç; Olutaş, Murat; Dede, Didem; Demir, Hilmi Volkan
Doped nanocrystals are instrumental to the high‐performance luminescent solar concentrators (LSCs) and the color conversion devices. Recently, copper (Cu)‐doped three and four monolayer (ML) thick CdSe nanoplatelets (NPLs) have been shown superior to the existing Cu‐doped quantum dots (QDs) for their use in LSCs. However, additional improvement in the LSC performance can be achieved by further redshifting the emission into the near‐infrared (NIR) region of electromagnetic spectrum and increasing the absorbed portion of the solar irradiation. Cu‐doping into higher thicknesses of these atomically flat NPLs (e.g., ≥5 ML) can achieve these overarching goals. However, addition of the dopant ions during the nucleation stage disturbs this high‐temperature growth process and leads to multiple populations of NPLs and QDs. Here, by carefully controlling the precursor chemistry the successful doping of Cu in five ML thick NPLs by high‐temperature nucleation doping method is demonstrated. The optimized synthesis method shows nearly pure population of doped five ML thick NPLs, which possess ≈150 nm Stokes‐shifted NIR emission with high quantum yield of 65 ± 2%. Structural, elemental, and optical studies are conducted to confirm the successful doping and understand the detailed photophysics. Finally, these materials are tested experimentally and theoretically for their performance as promising LSC materials.
Open Access
Near-unity emitting copper-doped colloidal semiconductor quantum wells for luminescent solar concentrators
(Wiley-VCH Verlag, 2017) Sharma, M.; Gungor K.; Yeltik A.; Olutas M.; Guzelturk, B.; Kelestemur Y.; Erdem, T.; Delikanli S.; McBride, J. R.; Demir, Hilmi Volkan
Doping of bulk semiconductors has revealed widespread success in optoelectronic applications. In the past few decades, substantial effort has been engaged for doping at the nanoscale. Recently, doped colloidal quantum dots (CQDs) have been demonstrated to be promising materials for luminescent solar concentrators (LSCs) as they can be engineered for providing highly tunable and Stokes-shifted emission in the solar spectrum. However, existing doped CQDs that are aimed for full solar spectrum LSCs suffer from moderately low quantum efficiency, intrinsically small absorption cross-section, and gradually increasing absorption profiles coinciding with the emission spectrum, which together fundamentally limit their effective usage. Here, the authors show the first account of copper doping into atomically flat colloidal quantum wells (CQWs). In addition to Stokes-shifted and tunable dopant-induced photoluminescence emission, the copper doping into CQWs enables near-unity quantum efficiencies (up to ≈97%), accompanied by substantially high absorption cross-section and inherently step-like absorption profile, compared to those of the doped CQDs. Based on these exceptional properties, the authors have demonstrated by both experimental analysis and numerical modeling that these newly synthesized doped CQWs are excellent candidates for LSCs. These findings may open new directions for deployment of doped CQWs in LSCs for advanced solar light harvesting technologies.
Open Access
One-dimensional copper (II) coordination polymer as an electrocatalyst for water oxidation
(Wiley-VCH Verlag, 2017) Mishra, R.; Ülker, E.; Karadas, F.
Although cobalt-based heterogeneous catalysts are the central focus in water oxidation research, interest in copper-based water oxidation catalysts has been growing thanks the great abundance of copper and its biological relevance. Several copper oxides have recently been reported to be active catalysts for water oxidation. In this study, a heterogeneous copper-based water oxidation catalyst that is not an oxide has been reported for the first time. Single-crystal XRD studies indicate that the compound is a one-dimensional coordination compound incorporating copper paddle-wheel units connected through phosphine dioxide ligands. The catalyst exhibits an onset potential of 372 mV at pH 10.2, whereas an overpotential of only 563 mV is required to produce a current density of 1 mA cm−2. In addition to cyclic voltammetric and chronoamperometric studies, an investigation into the effect of pH on the catalytic activity and the robustness of the catalyst using long-term bulk electrolysis (12 h) is presented.
Open Access
Phytoremediation of Cu, Cr and Pb mixtures by lemna minor
(2013) Üçüncü, E.; Tunca, E.; Fikirdeşici, S.; Özkan, A.D.; Altindaǧ, A.
The present study reports the capacity of the aquatic macrophyte Lemna minor to remediate combinations of Cu(II), Pb(II) and Cr(III) from a simulated natural environment. The effect of these metal mixtures on the growth of L. minor was also investigated using growth rate and biomass inhibition calculations. L. minor was successful in removing Cr and Pb from the water, and it remained an effective remediation agent when both metals were present in the environment. However, a relatively low absorption capacity was observed for Cu, increasing concentrations of which were associated with significant decreases in growth rate. No statistically significant difference was found between the 24 h and 7 days absorption rates of Cu, Pb and Cr, suggesting that, at the concentrations tested, equilibrium occurs within 24 h of metal exposure. © 2013 Springer Science+Business Media New York.
Open Access
Standing mesochannels: mesoporous PdCu films with vertically aligned mesochannels from nonionic micellar solutions
(American Chemical Society, 2018) Iqbal, M.; Kim, J.; Yuliarto, B.; Jiang B.; Li C.; Dağ, Ömer; Malgras, V.; Yamauchi, Y.
Mesoporous bimetallic palladium (Pd) alloy films with mesochannels perpendicularly aligned to the substrate are expected to show superior electrocatalytic activity and stability. The perpendicular mesochannels allow small molecules to efficiently access the active sites located not only at the surface but also within the film because of low diffusion resistance. When compared to pure Pd films, alloying with a secondary metal such as copper (Cu) is cost-effective and promotes resistance against adventitious poisoning through intermediate reactions known to impair the electrocatalytic performance. Here, we report the synthesis of mesoporous PdCu films by electrochemical deposition in nonionic micellar solutions. The mesoporous structures are vertically aligned on the substrate, and the final content of Pd and Cu can be adjusted by tuning the initial precursor molar ratio in the electrolyte solution.
Open Access
TL/OSL studies of Li2B4O7:Cu dosimetric phosphors
(2013) Aydin, T.; Demirtaş H.; Aydin, S.
Dosimetric phosphors of Cu-doped lithium tetraborate (Li2B 4O7:Cu) were produced using a sintering technique in a laboratory environment and characterized using Scanning Electron Microscopy (SEM) and X-ray Diffractometry (XRD). The thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of powdered (Li2B 4O7) phosphor doped with copper at different concentrations (0.020-0.025 wt %) were studied. The Cu-doped Li 2B4O7 phosphor material has two dominant TL glow peaks, and the maximum TL responses of the peaks are at 115 C and 243 C in the range of 0 C-310 C. The TL response of the Cu-doped lithium tetraborate is approximately 900 times more sensitive than undoped lithium tetraborate. The TL and OSL signal intensities increase as the beta radiation doses increase up to approximately 150.00 Gy and 76.50 Gy, respectively. The OSL dose-response curve is linear up to a dose range of 12.00 Gy for Cu-doped Li2B 4O7 dosimetric phosphors. The time-dependent fading behavior of the Cu-doped lithium tetraborate was found to be quite stable over long time durations. In addition, the repeatability of the OSL dose measurements were determined to be 2/3 lower compared to the TL measurements. The reproducibility of the OSL measurements was approximately 5%. Based on the TL and OSL results, the prepared phosphors can be used to measure beta doses ranging from 10 μGy to 150.00 Gy and 76.50 Gy, respectively, by using the TL and OSL techniques, with confidence limits of approximately 7% and 3-4%, respectively. © 2013 Elsevier Ltd. All rights reserved.