Abstract

The levels of six chemical elements (mercury, arsenic, lead, cadmium, zinc and copper) were examined in two species of Pacific salmon, genus Oncorhynchus, pink salmon (O. gorbuscha ), and chum salmon (O. keta ) that were caught in the Kuril waters in July 2013. Concentrations of toxic elements (Hg, As, Pb, Cd) in both species were shown to be below the maximum concentration limits of these trace elements for seafood. The concentrations of these elements were compared between wild salmon and hatchery salmon of the Pacific and Atlantic oceans.

Abstract

Interactions of metals with the biomass of plant organisms, including algae, are of interest for biology, biogeochemistry and biotechnology. This work studies the interactions of the unique thermophilic red algae Galdieria sulphuraria (Class: Rhodophyta, Family: Cyanidiaceae) with copper and lead in the aquatic environment. This extremophilic, acidophilic organism is found in such ecosystems as hot springs and geothermal habitats. This paper presents the results of experiments with the biomass and mortmass of this organism. The results indicate that the biomass of this organism immobilises copper after incubation in aquatic medium with heavy metals. Lead was also added to the incubation environment, but no immobilisation of lead from the aquatic environment was observed. The mortmass of G. sulphuraria immobilised neither copper nor lead.

Abstract

Aim of the present work is to investigate mechanical and metallurgical characteristics of continuous wave CO2 laser welded dissimilar couple of AISI 304 stainless steel and commercially pure copper sheets in autogenous mode. Metallurgical analysis of the fusion zone has been done to understand the mixing and solidification behavior. Macroscopic examination has been carried out to observe the macro-segregation pattern of Cu, Fe and Cr rich phases in different zones, and the thickness of HAZ was found to be around 10 µm. The micro-channels formed from the steel side to weld pool describe that the copper solidifies first and provides the nucleation surface for the residual melt to grow. These tubular micro-channels formed may be due to carbide precipitation. The EDS analysis conforms the well mixing of SS and Cu inside the weld pool. The mechanical properties in terms of tensile stress found up to 201 MPa and the fracture are obtained outside the weld zone. Microhardness measurements over the fusion zone have been done to understand the keyhole growth and quenching, solidification sequence and stress distribution over the full area.