Copper Oxide Nanoparticles Impact Several Toxicological Endpoints and Cause Neurodegeneration in \u3cem\u3eCaenorhabditis elegans\u3c/em\u3e

Engineered nanoparticles are becoming increasingly incorporated into technology and consumer products. In 2014, over 300 tons of copper oxide nanoparticles were manufactured in the United States. The increased production of nanoparticles raises concerns regarding the potential introduction into the environment or human exposure. Copper oxide nanoparticles commonly release copper ions into solutions, which contribute to their toxicity. We quantified the inhibitory effects of both copper oxide nanoparticles and copper sulfate on C. elegans toxicological endpoints to elucidate their biological effects. Several toxicological endpoints were analyzed in C. elegans, including nematode reproduction, feeding behavior, and average body length. We examined three wild C. elegans isolates together with the Bristol N2 laboratory strain to explore the influence of different genotypic backgrounds on the physiological response to copper challenge. All strains exhibited greater sensitivity to copper oxide nanoparticles compared to copper sulfate, as indicated by reduction of average body length and feeding behavior. Reproduction was significantly reduced only at the highest copper dose, though still more pronounced with copper oxide nanoparticles compared to copper sulfate treatment. Furthermore, we investigated the effects of copper oxide nanoparticles and copper sulfate on neurons, cells with known vulnerability to heavy metal toxicity. Degeneration of dopaminergic neurons was observed in up to 10% of the population after copper oxide nanoparticle exposure. Additionally, mutants in the divalent-metal transporters, smf-1 or smf-2, showed increased tolerance to copper exposure, implicating both transporters in copper-induced neurodegeneration. These results highlight the complex nature of CuO nanoparticle toxicity, in which a nanoparticle-specific effect was observed in some traits (average body length, feeding behavior) and a copper ion specific effect was observed for other traits (neurodegeneration, response to stress)

Some metal-graphite and metal-ceramic composites for use as high energy brake lining materials

Materials were studied as candidates for development as potential new aircraft brake lining materials. These families were (1) copper-graphite composites; (2) nickel-graphite composites; (3) copper - rare-earth-oxide (gadolinium oxide (Gd2O3) or lanthanum oxide (La2O3)) composites and copper - rare-earth-oxide (La2O3) - rare-earth-fluoride (lanthanum fluoride (LaF3)) composites; (4) nickel - rare-earth-oxide composites and nickel - rare-earth-oxide - rare-earth-fluoride composites. For comparison purposes, a currently used metal-ceramic composite was also studied. Results showed that the nickel-Gd2O3 and nickel-La2O3-LaF3 composites were comparable or superior in friction and wear performance to the currently used composite and therefore deserve to be considered for further development

Modeling the effect of copper availability on bacterial denitrification

When denitrifying bacteria such as Paracoccus denitrificans respire anaerobically they convert nitrate to dinitrogen gas via a pathway which includes the potent greenhouse gas, nitrous oxide (NO). The copper-dependent enzyme Nitrous Oxide reductase (Nos) catalyzes the reduction of NO to dinitrogen. In low-copper conditions, recent experiments in chemostats have demonstrated that Nos efficiency decreases resulting in significant NO emissions. For the first time, a chemostat-based mathematical model is developed that describes the anaerobic denitrification pathway based on Michaelis-Menten kinetics and published kinetic parameters. The model predicts steady-state enzyme levels from experimental data. For low copper concentrations, the predicted Nos level is significantly reduced, whereas the levels for the non copper-dependent reductases in the pathway remain relatively unaffected. The model provides time courses for the pathway metabolites that accurately reflect previously published experimental data. In the absence of experimental data purely predictive analyses can also be readily performed by calculating the relative Nos level directly from the copper concentration. Here, the model quantitatively estimates the increasing level of emitted NO as the copper level decreases. We have developed a mathematical model for the denitrification pathway based on existing experimental results, Michaelis-Menten kinetics and experimentally obtained kinetic constants. This is the first such model to incorporate the copper concentration in order to predict emissions of the potent greenhouse gas, nitrous oxide (NO), as well as the other nitrogenous compounds in the pathway. The model predicts increasing NO emissions as the copper level is lowered, in agreement with experimental observations in chemostats. © 2013 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Application of Copper Fungicide and Row Covers to Control Phytophthora Seedling Blight Disease on Cocoa

Phytophthora seedling blight disease is one of the important diseases in cocoa. The disease is caused by the fungus of Phytophthora palmivora belongs to class Oomycetes. The aim of this research was to determine the effectiveness of the use of row covers and copper oxide fungicide applications to control seedling blight Phytophthora. Covering treatment was to place cocoa seedlings inside bamboo frame covered by transparent plastic in order to avoid from rainfall effect. The research was conducted in the Kaliwining Experimental Station at Indonesian Coffee and Cocoa Research Institute (ICCRI). Experiments were carried out four treatments and repeated 6 times. Each treatment consists of 100 seedlings planted in polybags and placed in the nursery area with a protective paranet. The treatment consisted of (1) row covers, (2) spraying of copper oxide 0.2%, (3) a combination of row covers and copper oxide 0.2% and (4) control (no covers and spray). Observations made 7 days after treatment with an interval of 7 days for 10 weeks. The results showed that row covers able to prolong the incubation period of the disease for 14 days, while the application of row covers + copper oxide 0.2% was able to save cocoa seedlings by 96.2%

Aluminium or copper substrate panel for selective absorption of solar energy

A method for making panels which selectively absorb solar energy is disclosed. The panels are comprised of an aluminum substrate, a layer of zinc thereon, a layer of nickel over the zinc layer and an outer layer of solar energy absorbing nickel oxide or a copper substrate with a layer of nickel thereon and a layer of solar energy absorbing nickel oxide distal from the copper substrate

Thermodynamic investigations on the growth of CuAlO2_2 delafossite crystals

Simultaneous differential thermal analysis (DTA) and thermogravimetric (TG) measurements with copper oxide/aluminum oxide mixtures were performed in atmospheres with varying oxygen partial pressures and with crucibles made of different materials. Only sapphire and platinum crucibles proved to be stable under conditions that are useful for the growth of CuAlO$_2$ delafossite single crystals. Then the ternary phase diagram Al$_2$O$_3$-CuO-Cu and its isopleth section Cu$_2$O-Al$_2$O$_3$ were redetermined. Millimeter sized crystals could be obtained from copper oxide melts with 1-2 mol % addition of aluminum oxide that are stable in platinum crucibles held in oxidizing atmosphere containing 15-21 % oxygen.Comment: 12 pages, 7 figure

Performance of silica-supported copper oxide sorbents for SOx/NOx-removal from flue gas II. Selective catalytic reduction of nitric oxide by ammonia

The selective catalytic reduction (SCR) of nitric oxide by ammonia was studied for silica-supported copper oxide particles to be used as a sorbent/catalyst in a continuous process for the simultaneous removal of SOx and NOx from flue gases. The SCR-behaviour was determined as a function of the sulphation degree, i.e. the fraction of copper oxide converted to copper sulphate, at temperatures ranging from 20 to 450°C. Up to 350°C, the fresh catalyst with 0% CuSO4 showed a high selectivity towards production of nitrogen and water by the reaction of nitric oxide with ammonia and oxygen. At higher temperature, nitric oxide removal efficiencies decreased due to the oxidation of ammonia by oxygen. With an increase of the sulphation degree, the maximum temperature for selective catalytic reduction of nitric oxide gradually increased up to 420°C for a sulphation degree of 80%. In addition, the maximum nitric oxide removal efficiency increased as well. After regeneration of catalyst particles with a sulphation degree of 80%, realised by reduction with hydrogen and subsequent re-oxidation, the catalytic behaviour was similar to that of fresh catalyst particles with a sulphation degree of 5%. This is ascribed to the formation of some Cu2S during the reduction, which is oxidised to CuSO4 in the subsequent oxidation step. Since the selectivity towards the reduction of nitric oxide with ammonia is maintained up to about 375°C, a temperature which is very suitable for SOx removal as well, the silica-supported CuO investigated can be applied as a sorbent/catalyst for the simultaneous removal of SOx and NOx from flue gases. The reaction rate constants for SOx and NOx removal appeared to be of the same order of magnitude provided that the reduced sorbent/catalyst enters the absorber directly, i.e. without a separate pre-oxidation

Preparation and electrical properties of dense micro-cermets made of nickel ferrite and metallic copper

Dense micro-cermets made of nickel ferrites and copper micrometric particles were obtained from partial reduction under hydrogenated atmosphere at 350 C of mixed copper nickel ferrites, and sintering in nitrogen at 980 C. The small copper particles are homogeneous in size and well dispersed in the spinel oxide matrix. No exudation of copper metal was observed after sintering. The micro-cermets prepared are semi-conducting materials with electrical conductivity lying from 44 to 130 S/cm at 980 C. Their overall characteristics make them interesting for inert anodes dedicated to aluminium electrolysis in melted cryolite

Scaling of the superfluid density in high-temperature superconductors

A scaling relation \rho_s \simeq 35\sigma_{dc}T_c has been observed in the copper-oxide superconductors, where \rho_s is the strength of the superconducting condensate, T_c is the critical temperature, and \sigma_{dc} is the normal-state dc conductivity close to T_c. This scaling relation is examined within the context of a clean and dirty-limit BCS superconductor. These limits are well established for an isotropic BCS gap 2\Delta and a normal-state scattering rate 1/\tau; in the clean limit 1/\tau \ll 2\Delta, and in the dirty limit 1/\tau > 2\Delta. The dirty limit may also be defined operationally as the regime where \rho_s varies with 1/\tau. It is shown that the scaling relation \rho_s \propto \sigma_{dc}T_c is the hallmark of a BCS system in the dirty-limit. While the gap in the copper-oxide superconductors is considered to be d-wave with nodes and a gap maximum \Delta_0, if 1/\tau > 2\Delta_0 then the dirty-limit case is preserved. The scaling relation implies that the copper-oxide superconductors are likely to be in the dirty limit, and that as a result the energy scale associated with the formation of the condensate is scaling linearly with T_c. The a-b planes and the c axis also follow the same scaling relation. It is observed that the scaling behavior for the dirty limit and the Josephson effect (assuming a BCS formalism) are essentially identical, suggesting that in some regime these two effects may be viewed as equivalent. This raises the possibility that electronic inhomogeneities in the copper-oxygen planes may play an important role in the nature of the superconductivity in the copper-oxide materials.Comment: 8 pages with 5 figures and 1 tabl