Risk assessment and copper geochemistry of an orchard irrigated with mine water: a case study in the semiarid region of Brazil.

This study aimed to evaluate mine water reuse, elucidating the potential problems related to trace metal biogeochemistry focusing on Cu dynamics in water, soil, and plants. Water samples were collected from a Cu mine and a reservoir used to store mine water. Additional samples were taken from soils from an uncultivated area and a banana orchard (irrigated with mine water for at least 10 years) and plant from the irrigated area. The following parameters were analyzed: pH, redox potential, dissolved ions in water samples (e.g., Ca2+, Mg2+, Na+, K+, Cu2+, SO 4 2- , and Cl-), bioavailable Cu and Cu solid-phase fractionation (in soils and reservoir sediments samples), as well as Cu content in banana plants. Mine water presents high dissolved Cu concentration (mean 2.3 ± 0.0 mg L-1), limiting its use for irrigation. Water storage at the reservoir increased water quality, reducing dissolved Cu concentration (mean 0.2 ± 0.0 mg L-1), due to adsorption/precipitation as carbonates (mean 131.8 ± 24.6 mg kg-1), organic matter (mean 1526.2 ± 4.7 mg kg-1) and sulfides (mean 158.4 ± 56.9 mg kg-1). Despite higher water quality at the reservoir, the use of mine water increased the amount of bioavailable Cu in soils, which was primarily associated with organic matter. Increased bioavailable Cu in the soil did not increase the Cu content of banana leaves but resulted in high Cu content of roots and fruit, increasing the risk of toxicity for the population.

The Critical Raw Materials Issue between Scarcity, Supply Risk, and Unique Properties.

This editorial reports on a thorough analysis of the abundance and scarcity distribution of chemical elements and the minerals they form in the Earth, Sun, and Universe in connection with their number of neutrons and binding energy per nucleon. On one hand, understanding the elements' formation and their specific properties related to their electronic and nucleonic structure may lead to understanding whether future solutions to replace certain elements or materials for specific technical applications are realistic. On the other hand, finding solutions to the critical availability of some of these elements is an urgent need. Even the analysis of the availability of scarce minerals from European Union sources leads to the suggestion that a wide-ranging approach is essential. These two fundamental assumptions represent also the logical approach that led the European Commission to ask for a multi-disciplinary effort from the scientific community to tackle the challenge of Critical Raw Materials. This editorial is also the story of one of the first fulcrum around which a wide network of material scientists gathered thanks to the support of the funding organization for research and innovation networks, COST (European Cooperation in Science and Technology).

Trypanosoma cruzi: biodistribution of technetium-99m pertechnetate in infected rats.

With the aim of investigating the biodistribution of technetium-99m pertechnetate ((99m)TcO4-) in rats infected with Y strain of Tripanosoma Cruzi, at the peak of parasitemia, (14th day of infection), we injected Wistar rats with 0.1 ml of (99m)TcO4- (3.7MBq). After 60 min, the percentage of radioactivity per gram was counted in several isolated organs and blood, using a gamma counter (1470 Wizard, PerkinElmer Finland). The uptake of (99m)TcO4- increased significantly in blood and decreased in the colon of infected animals (p<0.05). A significant reduction in serum iron and red blood cells and a significant increase in total proteins, leukocytes and lymphocytes in the infected rats were observed, compared with controls (p<0.05). A reduction in muscle layer thickness of the colon and mononuclear inflammation were observed. These results conclusively demonstrate that T. cruzi infection would be associated with changes in the biodistribution of (99m)TcO4- and in colon morphology, with potential clinical implications.

In vitro antibacterial efficacy of endodontic irrigants against Enterococcus faecalis.

OBJECTIVE: The objective of this study was to compare the in vitro antimicrobial activity of 2% chlorhexidine gel against Enterococcus faecalis with sodium hypochlorite in 2 different concentrations (1.5% and 5.25%). STUDY DESIGN: Eighty human lower premolars with single root canals were prepared, autoclaved, and infected for 7 days with E. faecalis monocultures. The roots were then separated into 5 experimental groups according to the irrigant solution used during the standardized preparation. To assess the antimicrobial action of the irrigant solutions, 3 microbial samples were taken: S1--initial (before the biomechanical preparation), S2--posttreatment (immediately after the biomechanical preparation), and S3--final (7 days after the biomechanical preparation). The microbiological samples were plated to count the colony-forming units (CFU). RESULTS: The 2% chlorhexidine gel and 5.25% sodium hypochlorite significantly reduced the E. faecalis CFU in the posttreatment and final microbiological samples. The 1.5% sodium hypochlorite also reduced the E. faecalis CFU immediately after the root canal instrumentation, but the E. faecalis CFU increased in the final sample showing no statistical difference from the control group. CONCLUSION: The 2% chlorhexidine gluconate gel and 5.25% sodium hypochlorite were effective in eliminating E. faecalis even 7 days after the instrumentation; moreover, the higher the concentration of sodium hypochlorite the better its antimicrobial action.