Incompatible elements in bottom sediments of the Itaipú Dam Reservoir by EDXRF

Journal of Radioanalytical and Nuclear Chemistry - Sediments play an important role in the distribution of trace elements in the aquatic system and act as a sink for metals. Incompatible elements...     

Phosphorus availability from bottom sediments of lakes using a nuclear technique

Availability of phosphorus from the bottom sediments of a lake plays an import role in the development of aquatic biota and in the enhancement of the eutrophication process. In this work, the³¹P–³²P isotopic exhange (E values) technique was applied to assess the potential influence of this phosphorus reservoir on the water quality of the Acaray and Yguazú Dams in the Easter Region of Paraguay. Samples analyzed were taken from the bottom sediments of the water body at different sites as well as from the shores. The method is reliable and yields information of potential ecological significance.This work has been done during field campaigns for the study of water quality and eutrophication that are being carried out by Hydroconsult for the Paraguayan-Brazilian entity, ITAIPU BINACIONAL, in the area of influence of the Itaipú Dam built on the Parana River by the two countries.     

Sediments of Ypacarai Lake

Bottom and sestonic sediments of Ypacarai Lake were invesetigated with XRF and Mössbauer techniques. The 120 km² lake, depth averages 1.8 m. In addition to the lakes use for recreation, its basin has economic significance. Sediments play an important role in the distribution of trace elements in the aquatic system and as a sink for metals. Bottom and seston samples were taken from 4 different sampling stations which were selected according the morphology and population sites on the shore. The concentration of toxic metals was found to be low and no adverse ecological impact should be expected. The main metallic ion component is iron (1.68%). Mössbauer studies showed this element appears as Fe³⁺. Iron²⁺ was not detected. We suggest that Fe³⁺ acts as the limiting element which controls the eutrophication process.This is in agreement with low values of phytoplancton counting found in water samples.     

Formal Connections for Families of Star Products

We define the notion of a formal connection for a smooth family of star products with fixed underlying symplectic structure. Such a formal connection allows one to relate star products at different points in the family. This generalizes the formal Hitchin connection, which was introduced by the first author. We establish a necessary and sufficient condition that guarantees the existence of a formal connection, and we describe the space of formal connections for a family as an affine space modelled on the formal symplectic vector fields. Moreover, we showthat if the parameter space has trivial first cohomology group, any two flat formal connections are related by an automorphism of the family of star products.     

An Overview of Biosensors Based on Glutathione Transferases and for the Detection of Glutathione

Glutathione transferases are enzymes involved in the detoxification against xenobiotics and noxious compounds. These enzymes catalyse a variety of reactions on many physiological and xenobiotic compounds using glutathione as a co-substrate. Moreover, many compounds are inhibitors of such enzymes. A wide array of biosensors based on glutathione transferases have been developed for analysing a variety of noxious compounds, as well as several biosensors devoted to the detection and quantification of glutathione and of glutathione transferases themselves. Here, we review the state of the art in this active field of research, highlighting the possible applications of such devices.