Effects of ECAE process on the fatigue crack growth rate of copper metal

In this study, the effects of the number of passes performed by the Equal Channel Angular Extrusion as a severe plastic deformation process on copper metal's microstructure and mechanical properties, especially its resistance to fatigue crack growth, have been investigated. The experimental results show that as the number of processes passes increases, the copper metal grains become finer and as a result less stress is concentrated at the starting points of the fatigue fracture, which delays the fracture. For example, after performing 8 ECAE process passes, the threshold values of fatigue crack growth increases by 113.2% relative to the base metal. Moreover, as the grains become smaller, the number of grains and consequently the number of grain boundaries will increase and thus more obstacles will be placed in the way of crack growth. Also, the SEM images indicate that many fine and equiaxed dimples in processed copper become smaller as the number of passes increases. This shows that finer and more equiaxed grains will be obtained by repeating the ECAE process and thus repeating the occurrence of recrystallization. It was cleared that this process improves the mechanical properties of the copper other than the failure strain. However, by increasing the number of process passes, this problem can be significantly reduced. Highlights The fine grains considerably delay the fatigue fracture By ECAE process, the threshold value of fatigue crack growth increases by 113.2% All zones resulting from fatigue fracture are recognizable in fractured ECAE sample The SEM images indicate that a ductile failure has occurred in the tensile samples

Plant Based Biosynthesis of Copper Nanoparticles and its Efficacy on Seed Viability and Seedling Growth in Peanut (Arachis hypogaea Linn.)

Nano-fertilizers can easily adsorb into the plant and can increase the reactive points in the plant and hence are treated as an efficient alternative to the conventional fertilizers. Based on this, the present study was intended to synthesize copper nanoparticles (CuNPs) using aqueous root extract of Schrebera swietenioides Roxb. as green reducing agent. The synthesized nanoparticles were studied for its effectiveness on enhancement of seed germination and plant growth promotion on peanut (Arachis hypogaea Linn.). The formation of nanoparticles was confirmed by observing colour change in the reaction mixture, which shows characteristic absorption maxima at 340 nm. The SEM and TEM analysis confirmed that the nanoparticles were in monodispersed with spherical to irregular shape with an average particle size of 35 nm. The EDX analysis confirmed that the nanoparticles contain 82.5% copper metal. The synthesized nanoparticles were applied for its seed germination enhancement activity on peanut seeds and results confirms that the nanoparticles were significantly enhances the germination of peanut seeds with decrease in mean germination time. The peanut plant growth also enhances when compared with metal solution treatment and untreated plants. The root length of CuNPs treated plants was observed to be 9.27 ± 0.15 cm, which is significantly more than the untreated (6.40 ± 0.10 cm) as well as treated copper metal (7.13 ± 0.25 cm) plants. The shoot length of 19.13 ± 0.20 cm was observed for nano-treated plants and is greatly enhanced than the untreated (10.30 ± 0.20 cm) and treated copper metal (11.27 ± 0.25 cm) plants. The protease activity on day 5 of the germination study was found to be 0.904 ± 0.004, 0.133 ± 0.002 and 0.095 ± 0.002 units/mL, respectively for the peanut seeds treated with CuNPs, copper metal solution and untreated conditions. The catalase activity at 5th day of seed germination studies the activity was observed to be 45.177 ± 0.192, 23.691 ± 0.074 and 18.331 ± 0.209 units/min/g, respectively for CuNPs treated, copper sulphate treated and untreated pea nut seeds. The water update of the nano treated seeds was observed to be very high along with high quantity of photosynthetic pigments when compared with the other treatments in the study. Based on the results achieved, it can be confirmed that the nano-treatment enhances the seed germination and plant growth promotion on peanut seeds.

Copper(II)-MOF Containing Glutarate and 4,4′-Azopyridine and Its Antifungal Activity

Antifungal activities of MOFs (metal organic frameworks) have been demonstrated in studies, and improvement in efficiency of fungal inactivation is a critical issue in the application of MOFs. In this study, we employed 4,4′-azopyridine (AZPY) in the construction of MOF to improve its antifungal activity. Three-dimensional (3D) copper metal organic framework containing glutarate (Glu) and AZPY (Cu(AZPY)-MOF) was synthesized by a solvothermal reaction. Glutarates bridge Cu2 dinuclear units to form two-dimensional (2D) layers, and these layers are connected by AZPY to form a 3D framework. When spores of two fungi, Candida albicans and Aspergillus niger, were treated with Cu(AZPY)-MOF for one day, number of CFU (colony forming unit) was continuously reduced over treated MOF concentrations, and maximum 2.3 and 2.5 log10CFU reductions (approximately 99% reduction) were observed in C. albicans and A. niger, respectively. Small amounts of CuII ions and AZPY released from Cu(AZPY)-MOF were not critical for fungal inactivation. Our results indicate that the level of antifungal activity of Cu(AZPY)-MOF is greater than that of Cu-MOF without AZPY constructed in our previous study, and intercalation of AZPY is able to improve the antifungal activity of Cu(AZPY)-MOF.

Copper use in organic agriculture in twelve European countries.

Reduction of copper-based fungicides with the final aim of phasing out has a high priority in European policy as well as in organic agriculture. Our survey aims at providing an overview of the current use of copper-based plant protection products in European organic agriculture and the need for alternatives to allow policy makers to develop strategies for a complete phasing out. Due to a lack of centralized databases on pesticide use, our survey combines expert knowledge on permitted and real copper use per crop and country with statistics on organic area. In the 12 surveyed countries, covering together 83% of the European organically managed horticultural area, we calculated approximately 3258 t copper metal per year are consumed by organic agriculture, equalling to 53% of the permitted annual dosage. This amount is split between olives (1263 t y-1, 39%), grapevine (990t y-1, 30%), and almonds (317 t y-1, 10%), followed by other crops with much smaller annual uses (<80 t y-1). Potato, usually considered a highly demanding plant for copper inputs, only uses 39 t y-1 of copper per year. In 56% of the allowed cases (countries × crops), farmers use less than half of the allowed amount, and in 27% less than a quarter, with some variability between countries. Considering the large volumes of copper used annually, replacement of copper seems only feasible if all preventive strategies from the crop protection pyramid are fully implemented and several affordable alternative plant protection products are successfully brought to the market.