NITRATE REMOVAL POTENTIAL OF DIFFERENT MICROBIAL CONSORTIA, FEASIBLE FOR WASTEWATER TREATMENT IN RAS

In Recirculating Aquaculture System (RAS) the water effluent from fish tanks is reused after cleansing mainly with respect to organic substances, nitrate (NO3 -), nitrite (NO2 -), ammonium (NH4 +) and phosphate (PO4 -3) ions. One of the most used and promising cleansing techniques in modern RAS is the biological treatment of wastewaters performed by denitrifying bacteria which can convert the NO3 - to N2. In this study we estimated the aerobic denitrifying performances of different microbial consortia isolated from various sources, feasible to be further used in RAS. The kinetics of NO3 - consumption in either batch or discontinuous conditions, on synthetic culture media with acetate or ethanol as sole carbon source and nitrate as the main final electron acceptor, has been characterized. The experimental data showed that the selected microbial populations can clean water with efficiencies between 86% to100%, matching the requirements of international laws and making them suitable for employment in wastewater treatment in RAS

First record of Rhabdoceras suessi (Ammonoidea, Late Triassic) from the Transylvanian Triassic Series of the Eastern Carpathians (Romania) and a review of its biochronology, paleobiogeography and paleoecology

Abstract The occurrence of the heteromorphic ammonoid Rhabdoceras suessi Hauer, 1860, is recorded for the first time in the Upper Triassic limestone of the Timon-Ciungi olistolith in the Rarău Syncline, Eastern Carpathians. A single specimen of Rhabdoceras suessi co-occurs with Monotis (Monotis) salinaria that constrains its occurrence here to the Upper Norian (Sevatian 1). It is the only known heteromorphic ammonoid in the Upper Triassic of the Romanian Carpathians. Rhabdoceras suessi is a cosmopolitan species widely recorded in low and mid-paleolatitude faunas. It ranges from the Late Norian to the Rhaetian and is suitable for high-resolution worldwide correlations only when it co-occurs with shorter-ranging choristoceratids, monotid bivalves, or the hydrozoan Heterastridium. Formerly considered as the index fossil for the Upper Norian (Sevatian) Suessi Zone, by the latest 1970s this species lost its key biochronologic status among Late Triassic ammonoids, and it generated a controversy in the 1980s concerning the status of the Rhaetian stage. New stratigraphic data from North America and Europe in the subsequent decades resulted in a revised ammonoid biostratigraphy for the uppermost Triassic, the Rhaetian being reinstalled as the topmost stage in the current standard timescale of the Triassic. The geographic distribution of Rhabdoceras is compiled from published worldwide records, and its paleobiogeography and paleoecology are discussed

Structural Changes in the Perovskitic Compounds Series Sr2Mg1-xMIIxMoO6

Two series of perovskite type compounds (Sr2Mg1-xZnxMoO6 and Sr2Mg1-xNixMoO6) are characterized from the structural point of view. The synthesis conditions are briefly described. The cation distribution of the two series compounds were determined by X-ray diffraction

Standardless PIXE analysis of thick biomineral structures

The particle-induced X-ray emission (PIXE) of thick biomineral targets provides pertinent surface analysis, but if good reference materials are missing then complementary approaches are required to handle the matrix effects. This is illustrated by our results from qualitative and semiquantitative analysis of biomaterials and calcified tissues in which PIXE usually detected up to 20 elements with Z > 14 per sample, many at trace levels. Relative concentrations allow the classification of dental composites according to the mean Z and by multivariate statistics. In femur bones from streptozotocin-induced diabetic rats, trace element changes showed high individual variability but correlated to each other, and multivariate statistics improved discrimination of abnormal pathology. Changes on the in vitro demineralization of dental enamel suggested that a dissolution of Ca compounds in the outermost layer results in the uncovering of deeper layers containing higher trace element levels. Thus, in spite of significant limitations, standardless PIXE analysis of thick biomineral samples together with proper additional procedures can provide relevant information in biomedical research