Changes In Cu Content Research Articles

The effect of alkaline earth metals Ca, Mg on Cu–Fe catalysts synthesized by solvothermal method and their CO2 hydrogenation performance

Catalytic hydrogenation of CO2 to hydrocarbons reduces carbon emissions and makes better use of CO2 as a C1 resource to supplement chemical feedstocks. Herein, we report the effect of the introduction of Ca on the composition and performance of Cu–Fe catalysts synthesized by hydrothermal methods during the synthesis process. The catalysts were characterized by ICP, SEM, XRD, TEM, H2-TPR, CO2-TPD, N2 adsorption and desorption, and XPS. The results showed that the variation of the Ca (or Mg)Cu feeding ratio causes the change of Cu content in the catalyst. The change in Cu content also caused a change in the catalytic performance of the catalyst. In particular, the Cu content in the catalyst was 3.33% at Ca: Cu = 4:12. At this time, the highest CO2 conversion of 49.37% and C5+ selectivity of 59.89% were achieved with the reaction conditions (320 °C, 3 MPa, 12,000 mL·g-1 cat·h−1, N2/CO2/H2 = 12/12/36, TOS: 8 h) for the Cu–Fe catalyst. Further testing and analysis revealed that the increase in Cu content leads to enhanced Cu–Fe interaction in the catalyst, which is the fundamental reason for the change in catalytic performance.

Divergent prokaryotic microbial assembly, co-existence patterns and functions in surrounding river sediments of a Cu-polymetallic deposit in Tibet

The exploitation of polymetallic deposits produces large amounts of mine drainage, which poses great challenges to the surrounding aquatic ecosystem. However, the prokaryotic microbial community assembly and co-existence patterns in the polluted area are poorly understood, especially in high-altitude localities. Herein, we investigated the prokaryotic microbial assembly, co-existence patterns and their potential functional responses in surrounding river sediments of a Cu-polymetallic deposit in Tibet. The sediments from mine drainage and surrounding tributaries exhibited distinct geochemical gradients, especially the changes in Cu content. The microbial community structure changed significantly, accompanied by decreased richness and diversity with increased Cu content. Interestingly, the relative abundances of some potential functional bacteria (e.g., Planctomycetota) actually increased as the Cu levels raised. In low contaminated area, ecological drift was the most important assembly process, whereas deterministic processes gained importance with pollution levels. Meanwhile, negative interactions in co-occurrence networks were more frequent with higher modularity and reduced keystone taxa in high contaminated area. Notably, the functions related to ABC transporters and quorum sensing (QS) were more abundant with high Cu content, which helped bacteria work together to cope with the stressful environment. Taken together, the physicochemical gradients dominated by Cu content drove the distribution, assembly and co-existence patterns of microbial communities in surrounding river sediments of a Cu-polymetallic deposit. These findings provide new insights into the maintenance mechanisms of prokaryotic microbial communities in response to heavy metal stress at high altitudes.

Copper substituted methyl ammonium lead bromide grown using Non-Aqueous emulsion based synthesis technique

Hybrid organic–inorganic lead halide perovskites have become a promising material in the field of optoelectronics because of their prospects in the opto-electronics industry. However, the presence of the element “Lead” makes them legislatively untouchable for large scale production and human use. Herein, we report a non-aqueous emulsion-based synthesis and characterization of Copper (Cu)-substituted methyl ammonium lead Bromide (CH3NH3Pb1-xCuxBr3) perovskite nanoparticles which has not been reported previously. This technique enables the synthesis of quantum confined nanostructures by precipitation from the colloidal mixture. The structural characterization of all the samples showed that the crystallization occurs in the orthorhombic phase for the pristine and copper substituted methyl ammonium lead bromide nanostructure. The samples prepared with the precursor stoichiometry of CH3NH3Pb0.6Cu0.4Br3 and CH3NH3Pb0.5Cu0.5Br3 exhibited improved crystallinity relative to the un-substituted perovskite material. We report that as Cu content increases the average crystalline size increases which leads to decrease in optical band gap. The change in Cu content did not alter the excitonic absorption indicating that the quality of the material was not compromised as a result of the Cu substitution.

Effect of Cu Addition on Microstructure and Hardness of As-Cast and Heat-Treated High-Cr Cast Iron

The objective of the present study is to investigate the effect of Cu addition on microstructure and hardness of hypoeutectic high-Cr cast irons (26 wt% Cr) in as-cast and heat-treated conditions. As-cast specimens with varying amount of copper (Cu) addition were produced using an industrial grade high-frequency induction furnace. As-cast specimens were heat-treated in a box furnace using a typical reversed heat treatment sequence where subcritical heat treatment was followed by destabilization heat treatment. Microstructural analysis of the as-cast and heat-treated specimens was carried out using an optical microscope and Feritscope to understand the effect of Cu addition on the microstructure. The bulk hardness of all the specimens was measured using a Brinell hardness tester. The obtained result shows that the microstructures of the as-cast specimens mostly consist of austenitic dendrite matrix with γ+ M7C3 eutectic colony morphology. The eutectic colony consists of fine carbides in the central region and coarse carbides at the boundary region. High Cu containing specimen has a higher amount of thin rod-like M7C3 carbides, whereas low Cu containing specimen has a higher fraction of massive carbide morphology. Heat-treated specimens with various Cu content show mixed microstructure mostly consisting of retained austenite, transformed martensite, eutectic carbides, and secondary carbides. However, their relative volume fraction changes with the change in Cu content. Hardness result shows that higher Cu containing specimen has a lower hardness than the lower Cu contain specimens for both as-cast and heat-treated conditions. Although heat-treated specimens, in general, have higher hardness values than the as-cast specimens.

Alterations of Liver Histomorphology in Relation to Copper Supplementation in Inorganic and Organic Form in Growing Rats

Abstract The aim of this study was to define the effects of diet containing the same mineral content of mineral salt or amino acid chelate, and diet containing various levels of Cu amino acid chelate on liver histomorphometry in growing rats. Male Wistar rats were used in the 12th week experiment. The control group (n = 12) was fed standard diet, which provided Cu in an inorganic form at the level required for rats. The experimental animals were divided into four groups (each n = 12) depending on different levels (100%, 75%, 50%, 25% covered daily demand) of Cu supplementation in chelated form. Cu content was determined in the liver tissue and blood plasma. Immunohistochemical staining with caspase-3 antibody was performed. Microscopic assessment of the liver structure indicated that Cu supplementation did not change the liver architecture. However, histomorphometric analysis revealed a significant increase in the number of nuclei, total cell number, and multinucleated hepatocytes in rats supplemented with the organic form of Cu at the level of 25% compared with the control group. There was a considerable increase in the number of apoptotic cells and ballooning degeneration of hepatocytes, especially in groups supplemented with organic form of Cu covering the daily demand in 100% and 75%, in comparison to control group. Moreover, there was no Cu deposition in the liver and changes in Cu content in blood. Cu provided in the diet in organic form covering an amount of its minimum daily demand in 25% appears to be the least harmful with regard to the liver. It indicates that there is a need to establish the level of diet supplementation with Cu amino acid chelates.

Inter-population comparisons of copper resistance and accumulation in the red seaweed, Gracilariopsis longissima

Copper (Cu) resistance and accumulation of five populations of the red seaweed Gracilariopsis longissima collected from sites in south west England (Fal Estuary, Helford Estuary and Chesil Fleet) that differ in their degree of Cu contamination was assessed under controlled laboratory conditions, on two separate occasions (April and October). The effects of a range of Cu concentrations (0-250 μg l(-1)) on relative growth rates was the same for all populations with reductions observable at concentrations as low as 12 μg l(-1) and cessation of growth at 250 μg l(-1). There was no significant difference in the calculated EC(50) values for the April and October samples, with means of 31.1 and 25.8 μg l(-1), respectively. Over the range of concentrations used in this study, copper content increased linearly and the pattern of accumulation was the same for all populations at both time periods. From the linear regressions of the pooled data a concentration factor of 2.25 × 10(3) was calculated. These results imply that G. longissima has an innate tolerance to Cu and that populations have not evolved copper-tolerant ecotypes. In laboratory studies, accumulated Cu was released when transferred to 'clean' seawater with approximately 80% being lost after 8 days, with no significant difference between populations in their response. The results from a 30 days in situ transplantation experiment using two populations from the Fal Estuary provided further evidence for dynamic changes in Cu content in response to changes in Cu bioavailability. The findings in this study are discussed in the context of implications for seaweed biomonitoring.

Stoichiometric deviations along an ingot of CuGaSe2

The dependence of the structural parameters on compositional deviations of CuGaSe2 has been studied. These deviations have been induced along an ingot by a single fusion of the components at 1150 °C and subsequent slow cooling in a stationary ampoule in a vertical furnace. All along the sample a single chalcopyrite phase is present and a compositional gradient along the ingot was found by energy-dispersive analysis of X-rays (EDAX) measurements, the upper part being rich in Ga (series B) and the lower part in Cu (series A), with Cu/Ga ratios of 0·95 and 1·1 respectively. A hypothesis of the existence of two phases in the melt is proposed to explain these facts. The unit cell parameters, anion displacement and Cu and Ga occupation numbers in their sublattices were analysed by X-ray powder diffraction and Rietveld refinement methods. In series A the occupation numbers are near stoichiometry, while in series B a Cu defect appears. In both series, changes in unit cell parameter are related to changes in Cu content, suggesting the presence of a fraction of Cu ions either as interstitials or at Ga sites when Cu is in excess, or of Cu vacancies in its sublattice when there is a Cu deficiency. © 1998 John Wiley & Sons, Ltd.

Effects of cadmium on mineral nutrient concentrations in plants differing in tolerance for cadmium

The effects of 3 d treatments with 0.3 and 1.0 mg‐L‐1 of cadmium (Cd) on selected mineral nutrient composition in plants differing in tolerance for Cd were studied. The concentrations of potassium (K) decreased in Cd‐sensitive kidney bean and pea and that of manganese (Mn) decreased in the semi‐resistant rice and maize plants with increasing application of Cd in the culture solution. Copper (Cu) content increased in the roots of the plants above, but no changes in Cu contents were observed in the Cd resistant cucumber and pumpkin plants. Calcium (Ca), magnesium (Mg), and zinc (Zn) did not show any clear tendency with Cd applications in any of the plants examined. Water absorption by kidney bean was reduced by Cd, but that of rice and cucumber was not. Permeability of the plasma membrane of root cells may be affected by Cd, whereas absorption of some of the elements and water may be prevented.

Metabolism and pulmonary toxicity of intratracheally instilled cupric sulfate in rats

Though copper (Cu)-handling workers are known to be at risk to develop metal fume fever and acute respiratory failure, very little is known about the metabolic fate and pulmonary toxicity of Cu compounds deposited in the lung. We have investigated time-course and dose-related changes in Cu contents, the production of metallothionein (MT) and inflammatory responses in the rat lung following intratracheal instillation of cupric sulfate (CuSO 4). Intratracheally instilled Cu was cleared rapidly from the lung with a half-time of 7.5 h. Copper-binding MT was induced in the lung tissue following Cu instillation and the amount of MT increased with the dose of CuSO 4. However, the production of MT contributed little to the accumulation of Cu in the lung. The pulmonary toxicity of CuSO 4 was evaluated by examining time-course and dose-effect profiles of cytological and biochemical inflammatory indices (enzymes, protein and elements) retrieved in bronchoalveolar lavage fluids. These results revealed that the inflammatory indices reached maximum values in their activities and contents at 12 h to 3 days after instillation and a dose of 5 μg Cu/rat was sufficient to produce acute inflammatory responses in the rat lung.

Effect of small changes in composition on the electrical and structural properties of YBa2Cu3O7 thin films

Epitaxial thin films of YBa2Cu3O7 have been grown in situ by evaporation onto (001) MgO substrates. The composition was varied systematically to investigate the effects of changes in Cu content and Ba/Y ratio on the film properties. The results demonstrate that deviations from stoichiometry at the limit of resolution of most analytic techniques can have a large effect on structural and transport properties, as well as causing marked changes in surface morphology. The best properties (Jc≳3×106 A/cm2 at 77 K) are only found for a narrow range of compositions, which can be readily identified from the surface morphology.

Geochemical Analysis of Stream Sediments as a Tool for Environmental Monitoring: A Pigyard Case Study

A geochemical analysis of 11 chemical elements in stream sediments in the vicinity of a pig farm shows that geochemical exploration methods can be used for regional environmental monitoring of organic pollution. In a 5-sq-mi (12.95 km 2 ) area in southern Ontario, contaminated stream sediments showed definite increases in Mg, Ca, Na, K, and Zn. Changes in Cu content were inconclusive; Pb, Co, Ni, Fe, and Mn showed background averages. The study showed that stream sediments are affected by large-scale agricultural operations within a short period of time. It is conclusive that ground water will be affected as contamination continues.

ON THE EFFECT OF COPPER ON 61S

61S, which is a heat treatable high strength alloy, has the highest proof strength among Al-Mg2Si group. It is a peculiar alloy containing Cu. as its main element, the percentage ranging 0.15-0.40, in spite of its high corrosion resisting property. Being unable to find any literature on the behavior of its Cu. element, I have made some tracings, the results of which were reported herein and can be summarised as follows:-(1) Enumerated various wrought aluminum alloys of Al-Mg2Si group. which are now being used in actual practice. Particularly I have measured the mechanical properties of sheets in 61S various temper conditions, namely F, O, T4 and T6, and tried to make sure what are the most adequate conditions for its heat treatment.(2) To the composition of standard 61S, excepting Cu, Cu was added in various percentages. ranging from to 0.8. The material was rolled into 1mm. sheets. The variation in mechanical properties in accordance with the change in Cu content was measured under various temper conditions; namely as-rolled (F); annealed (O); solution treated and then quenched (W); naturally aged for 10 days after W treatment (T4); and tempered and artificially aged after W treatment (T6).(3) As the result, it was cleared that tensile strength increased with the increase in Cu content for every temper.(4) Proof strength for 0, T4 and T6 increases with the increment in Cu within the range of 0.08 to 0.17%, however the same does practically not increase even when Cu is added beyond the said limit.(5) Elongation decreases suddenly with a minor increase in Cu content, but the rate of decrease is somewhat smaller beyond the limit of 0.1-0.2%, while the said rate has such a tendency to increase again rapidly above 0.6% of Cu content.(6) The effect of artificial aging can be precieved in the increase of proof as well as tensile strength with the increase of Cu; especially within the range of 0.2 to 0.5% Cu the rate of hardening attains its highest value. Elongation remains almost constant.(7) Summarizing the above results, I can easily understand that the lower limit of Cu for 61S was determined as of 0.15. However, I thought it rather overhasty to determine the upper limit of Cu content simply from the facts that the rate of herdening in terms of tensile and proof strength does decrease and also elongation decreases beyond the limit of 0.6% of Cu content. Only after having made through corrosion tests, I will come back to this matter again.