Evidence For Copper Research Articles

Evidence of Copper and Iron Deposits of the Protohistoric City of Temesa

With the name ‘Temesa’ (Latin Tempsa), the ancients identified a settlement located along the Tyrrhenian coast of Calabria, cited by sources as an international metal exchange emporium. The town is mentioned by Homer as being famous in the ancient world for the production of bronze, and in the I century A.D. Strabo wrote that there were rich copper mines near the city. Many years of study led to the recognition of Temesa as a complex urban system located between the Oliva and Savuto rivers, near Amantea. To confirm this hypothesis, we searched, in the surrounding rocky outcrops, for the presence of minerals useful for the extraction of iron and copper. Samples of 3 different rock stratifications were taken near the protohistoric settlement of Serra Aiello. The observation under an polarized reflected light microscope and the X-ray diffraction patterns revealed the presence of many minerals useful for the extraction of iron and copper in every sample. The heating of samples under both oxidizing and reducing conditions helped us to better quantify copper and iron minerals content causing, at the same time, the appearance of a marked paramagnetic behavior that could be associated with the presence of goethite. X ray fluorescence analysis showed a high concentration of iron and a low copper content.

Glass ingots from the Uluburun shipwreck: Addition of glass cullet during manufacture and evidence for the changing context of New Kingdom Egyptian glass production in the late 18th Dynasty

Our recent LA-ICP-MS analyses of glass ingots from the Uluburun shipwreck along with additional samples from Egyptian sites, primarily Amarna, encourage us to question how and where the ingots were produced. Because almost all the approximately 200 glass ingots are either greenish blue, colored by copper, or purplish blue, colored by cobalt, we focus here on these colorants and their attendant trace elements. Based on the evidence for copper and antimony in cobalt-blue glass, we conclude that the most likely explanation is the addition of glass cullet during ingot production, in accordance with suggested evidence from glassmaking texts thought to date to the Late Bronze Age. By comparing the Uluburun ingots with glass from Amarna using multivariate statistics and trace element ratios, we determine that while a few of the ingots might be consistent with Amarna manufacture, the great majority are not, but rather represent production from other workshops, probably following those at Amarna. The importance of these workshops is suggested by our finding that over half of the cobalt-blue Mycenaean relief beads for which trace element data is available were made with Egyptian glass closer to that of the Uluburun ingots than to glass found at Amarna.

Microglia and Astrocytes in Alzheimer's Disease in the Context of the Aberrant Copper Homeostasis Hypothesis.

Evidence of copper’s (Cu) involvement in Alzheimer’s disease (AD) is available, but information on Cu involvement in microglia and astrocytes during the course of AD has yet to be structurally discussed. This review deals with this matter in an attempt to provide an updated discussion on the role of reactive glia challenged by excess labile Cu in a wide picture that embraces all the major processes identified as playing a role in toxicity induced by an imbalance of Cu in AD.

Electronic Structural Analysis of Copper(II)-TEMPO/ABNO Complexes Provides Evidence for Copper(I)-Oxoammonium Character.

Copper/aminoxyl species are proposed as key intermediates in aerobic alcohol oxidation. Several possible electronic structural descriptions of these species are possible, and the present study probes this issue by examining four crystallographically characterized Cu/aminoxyl halide complexes by Cu K-edge, Cu L2,3-edge, and Cl K-edge X-ray absorption spectroscopy. The mixing coefficients between Cu, aminoxyl, and halide orbitals are determined via these techniques with support from density functional theory. The emergent electronic structure picture reveals that Cu coordination confers appreciable oxoammonium character to the aminoxyl ligand. The computational methodology is extended to one of the putative intermediates invoked in catalytic Cu/aminoxyl-driven alcohol oxidation reactions, with similar findings. Collectively, the results have important implications for the mechanism of alcohol oxidation and the underlying basis for cooperativity in this co-catalyst system.

Characterising the morphological properties and surface composition of radium contaminated particles: a means of interpreting origin and deposition

Radioactive 'hot particles' that occur in the environment present specific challenges for health and environmental regulators as often their small size makes them difficult to detect, and they are easily dispersed and accidentally ingested or inhaled by members of the public. This study of nine hot particles recovered from the beach at Dalgety Bay, UK, uses a combination of gamma spectrometry, imaging microscopy and SEM-EDX in order to characterise their morphology and surface composition, thereby helping to identify their origin and source characteristics. The nine particles analysed showed great heterogeneity in their activities, physical form and elemental composition. The particle activities were dominated by (226)Ra and its daughters. Three distinct grouping of particles were identified based on their morphology (artefact, glassy and 'metal-rich'), whilst four distinct groupings (artefact, glassy, angular and porphyric, rounded and highly porous) were identified based on morphology and surface properties as seen in the SEM. Whilst the 'artefact' particles were little altered, the other particles showed evidence of incineration. All particles were in a size and/or shape class vulnerable to wind- or water-mediated transport. No correlations were found between morphology and chemical composition. SEM-EDX analysis revealed C, Si, Zn, Fe, Ca are common in the particles together with Ba, Ni, Pb, Cu, Mn and Ti. This is interpreted as the particles being derived from radium containing luminescent paint containing a Zn/S phosphor, a hydrocarbon base and other fillers and additives. Evidence of copper and steel alloys were also present in some particles, whilst one consisted of a hydrocarbon based 'capsule'. The combination of techniques employed here has enabled interpretation of the origins of the radioactive particles and given insights into the potential movement of particles within the local environment.

Assessment of heavy metal concentrations in urban grown vegetables in Thika Town, Kenya

Consumption of leafy vegetables grown in urban areas contaminated with heavy metals is a major source of health problems for both humans and animals. This study was conducted to analyze the heavy metal levels in tomato (Lycopersicon esculentumL.) and spinach (Spinacia oleracea L.) grown in Thika town. Heavy metal concentration was analyzed using Atomic Absorption Spectrometry. The mean concentrations of lead (Pb), Zinc (Zn) and cadmium (Cd) in all the samples were more than the maximum permitted concentrations while there was no evidence of copper (Cu) contamination. Heavy metal uptake differences by the vegetables were attributed to plant differences in tolerance. Further Lead (mgkg-1) concentration in the vegetables was above the maximum limit of 0.3 mgkg-1 accepted for human health by World Health Organization (WHO) standards. Due to increased consumption of vegetables by urban communities, we suggest that it is important to treat industrial effluents which are significant sources of heavy metals and phyto-extract excess metals from polluted environments to reduce health risks. Key words: Lycopersicon esculentum, Spinacia oleracea, lead, zinc, cadmium, copper, atomic absorption spectrometry.

Transient Capacitance Spectroscopy of Copper-Ion-Drifted Methylsilsesquiazane-Methylsilsesquioxane Interlayer Dielectrics

The evidence of copper (Cu) ion drift in low-dielectric-constant (low-k) interlayer films was obtained for the first time by transient capacitance measurements. The charge states of the electronic states related to Cu+ ions drifted into the low-k layer of Cu/low-k/SiO2/Si metal–insulator–semiconductor capacitors were altered by photo?electron injection from the p-Si substrate by applying a positive bias to the Cu layer under UV light illumination. A decrease in the time-dependent transient capacitance C(t) was attributed to the thermal emission of electrons from Cu-related electronic states. The trap level of the Cu-related electronic states was estimated to be approximately 0.9 eV below the conduction band edge in the bandgap of the low-k material.

Biotransference and biomagnification of selenium copper, cadmium, zinc, arsenic and lead in a temperate seagrass ecosystem from Lake Macquarie Estuary, NSW, Australia.

In this study the biotransference of selenium copper, cadmium, zinc, arsenic and lead was measured in a contaminated seagrass ecosystem in Lake Macquarie, NSW, Australia, to determine if biomagnification of these trace metals is occurring and if they reach concentrations that pose a threat to the resident organisms or human consumers. Selenium was found to biomagnify, exceeding maximum permitted concentrations for human consumption within carnivorous fish tissue, the highest trophic level examined. Selenium concentrations measured within carnivorous fish were also above those shown to elicit sub-lethal effects in freshwater fish. As comparisons are made to selenium concentrations known to effect freshwater fish, inferences must be made with caution. There was no evidence of copper, cadmium, zinc or lead biomagnification within the food web examined. Copper, cadmium, zinc and lead concentrations were below concentrations shown to elicit adverse responses in biota. Copper concentrations within crustaceans M. bennettae and P. palagicus were found to exceed maximum permitted concentrations for human consumption. It is likely that copper concentrations within these species were accumulated due to the essential nature of this trace metal for many species of molluscs and crustaceans. Arsenic showed some evidence of biomagnification. Total arsenic concentrations are similar to those found in other uncontaminated marine ecosystems, thus arsenic concentrations are unlikely to cause adverse effects to aquatic organisms. Inorganic arsenic concentrations are below maximum permitted concentrations for human consumption.

Evaluation of Copper Ion Drift in Low-Dielectric-Constant Interlayer Films by Transient Capacitance Spectroscopy

AbstractThe evidence of copper (Cu) ion drift in low-dielectric-constant (low-k) interlayer films is clearly shown by transient capacitance measurements for the first time. The bias-temperaturestress (BTS) was applied to the copper electrode of Cu/low-k/p-Si metal-insulator-semiconductor capacitors. After injecting photoelectrons into the low-k film from the substrate, time-dependence of the capacitance was measured. When BTS-applied samples were measured, a decrement of the capacitance was observed, whereas not observed without BTS. The decrement of the capacitance was attributed to thermal emission of electrons from copper-related electronic states. By assuming an attempt-to-escape frequency of the charge from the electronic states, the energy level of Cu was estimated to be 0.8–0.9 eV below the conduction band edge.

Ternary lithium nitridocuprates, Li3−x−yCuxN: crystal growth, bulk synthesis, structure and magnetic properties

Systematic studies within the ternary Li–Cu–N system have examined the effects of varying starting materials, transition metal stoichiometry, reaction temperature/duration and cooling rate on crystal growth and bulk phase formation of ternary nitridocuprates. Resulting lithium transition metal compounds, Li3−x−y□yCuxN (□=Li vacancy), have been characterised by single crystal and powder XRD. The maximum copper substituent level (x≈0.45) and vacancy level, y, appear insensitive to reaction temperature. Both vacancies and copper are disordered with Li when reaction mixtures are quenched (α-Li3N-type: P6/mmm, a≈3.7 Å, c≈3.8 Å, Z=1), whereas evidence of copper and/or vacancy ordering exists on slow cooling. Morphology of crystallites has been evaluated by SEM and magnetic properties have been investigated using squid magnetometry. Magnetic data show compounds exhibit temperature dependent paramagnetism in contrast to the parent nitride, Li3N.

Evidence for copper and 3,4,6-trihydroxyphenylalanine quinone cofactors in an amine oxidase from the gram-negative bacterium Escherichia coli K-12.

The cofactors present in a amine oxidase induced in Escherichia coli K-12 by growth on 2-phenylethylamine have been studied by spectroscopic methods. E.s.r. spectroscopy establishes the presence of cupric copper while resonance Raman spectroscopy on the phenylhydrazine derivative of the enzyme provides strong evidence for the oxidized form of 3,4,6-trihydroxyphenylalanine (TOPA) quinone. The amine oxidase should accordingly be classified as EC 1.4.3.6. This is the first report of such an amine oxidase in a Gram-negative bacterium.

The structure and magnetic characteristics of a holmium-1,2,3 superconductor with tetragonal symmetry

The structure of a superconducting, single crystal of holmium-1,2,3 has been shown to be tetragonal above and below the superconducting transition temperature by a combination of X-ray, neutron and electron diffraction techniques. Structural parameters, which included site-occupancy for all atoms, have been refined at 115 and 20 K and evidence for copper as well as oxygen deficiency is presented. There is no evidence that the structure involves twinning or a superlattice. The same crystal has been shown to sustain a critical current of ∼ 10 5 A/cm −2 and to exhibit a Meissner effect with T c =91.5 K. Crystal data: HoBa 2Cu 3O 7−δ. M r=742.2, tetragonal, spacegroup P4/mmm. At T=115 K, a=3.8598(2) A ̊ , c=11.6537(9) A ̊ , λ=1.3162 A ̊ , V=173.62(2) A ̊ 3 , R=3.3% for 124 reflexions; at T=20K, a=3.8592(3) A ̊ , c=11.6472(11) A ̊ , λ=1.3162 A ̊ , V=173.47(2) A ̊ 3 R=2.7% for 124 reflexions.

Oxidation-state assignments for galactose oxidase complexes from x-ray absorption spectroscopy. Evidence for copper(II) in the active enzyme

Oxidation-state assignments for galactose oxidase complexes from x-ray absorption spectroscopy. Evidence for copper(II) in the active enzyme

A structural study of the YBa2Cu3O7?x superconductor system

X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD) and analytical scanning electron microscopy have been employed to investigate the structure and microstructure together with the chemical nature of the YBa2Cu3O7−x superconductor system at different stages of preparation. XRD studies showed that the original mixture assumed a structure quite similar to that of the final superconductor phase after being sintered at about 900° C in air. While XPS results showed no evidence for copper in any valency other than 2, X-ray-induced Auger features confirmed the existence of monovalent copper at low temperatures. A small shoulder on the O1s spectrum in the final compound proved to be variant with the temperature. The intensity of this shoulder increased relative to the main O1s peak by lowering the temperature. This is believed to be due to the formation of monovalent copper on the top of the sample. Microstructural studies together with point analysis and X-ray mapping showed the existence of different phases in the final compound.

Copper catalysed reactions of di-t-butyl peroxide: evidence for copper(II) alkoxide intermediates and a non-radical reaction mechanism

Reaction of di-t-butyl peroxide, (ButO)2, with CuI chloride species gives CuII alkoxy chlorides which are intermediates in the oxidative carbonylation reaction of alcohols to dialkyl carbonate, oxalate, or succinate esters and evidence is presented that these reactions do not involve free radicals.

The Detection of Metallic Mordants by Energy Dispersive X-Ray Spectrometry: Part II. Historical Silk Textiles

Thirteen silk fibers from seven different historical silk textiles were subjected to EDS analysis. The major metallic elements detected were aluminum, iron, calcium, silicon and potassium. No evidence for copper, chromium, tin or zinc was found. These results were compared to analyses of known mordanted silk samples.

The Detection of Metallic Mordants by Energy Dispersive X-Ray Spectrometry: Part II. Historical Silk Textiles

Thirteen silk fibers from seven different historical silk textiles were subjected to EDS analysis. The major metallic elements detected were aluminum, iron, calcium, silicon and potassium. No evidence for copper, chromium, tin or zinc was found. These results were compared to analyses of known mordanted silk samples.

Cyclic voltammetric studies of copper(II) dipeptide complexes. Evidence for copper(I) dipeptide complexes in aqueous media

The reduction of the title complexes was studied by cyclic voltammetry in aqueous media. It proceeds through a one-electron process generating intermediate copper(I) dipeptide complexes. The copper(I) dipeptide complexes are found to be short-lived and undergo transformations eventually generating Cu 0 at the mercury electrode. The unchanged fraction of the copper(I) species is re-oxidised to the copper(II) complexes. The Cu 0 generated undergoes a two-electron oxidation at a more anodic potential than the copper(I) complexes. pH-dependence of the title complexes is also investigated by cyclic voltammetry.