Long-term nutrients and heavy metals concentration dynamics in aquatic ecosystems of Danube Delta

This study aims to make an overview of the last fifteen years of contamination freshwater, in the Danube river, branches and delta lakes. The water quality of the river and Delta lakes was described by analysing the data for nutrients and some heavy metals. The concentrations elements (n, Cd, Cu, Pb) in the water are compared with heavy metals in fish, captured in natural delta lakes. Bioconcentration factor (BCF) is described in some commercial fish species

Seasonal dynamics of the inorganic nutrients from auatic comple SomovaParche in 21

The existence of nitrogen compounds influence variety, abundance and nutritional value of aquatic organisms. This study aimes to analyze the dynamic of nutrient inorganic forms in spring (March), summer (July) and autumn (September) seasons, in 2016. The selected sampling points were: SomovaParcheş complex inlet (S1), Somova-Parches complex outlet channel into the Danube River (S2), rainwater and cooling water discharge from the industrial zone of Tulcea (S3), Casla lake (S4), Somova lake (S5), Parches lake (S6), Rotundu lake (S6). Study results show that the physico-chemical characteristics and surface water quality from the aquatic complex Somova-Parches are determined by natural factors (climate, flowing regime) and also by the effects of industrial activities of Tulcea town. Also, it were identified exceedings of maximum allowed concentrations for good ecological status, established by the Water Framework Directive transposed into Romanian legislation through MMGA Order 161/2006

Electrochemical behaviour of ternary Ni-Zn-P thin films deposition on steel substrate

572-577Ternary Ni-Zn-P alloy thin films  with a thickness of 15-20 μm are considered as a replacement for cadmium sacrificial coatings for anticorrosive protection of steel parts working in highly corrosive media. Anticorrosive Ni-Zn-P thin films has been electrochemically deposited from aqueous sulphate solutions on carbon steel substrate. The influence of bath composition (variable ZnSO4·7H2O contents) and electrodeposition type (potentiostatic or galvanostatic) on physical-chemical and corrosion characteristics of obtained films have been studied. Films are characterized by energy dispersive analysis (EDAX) and scanning electron microscopy (SEM). The corrosion tests are performed in 3% NaCl solution with optimal resulting values of -916.2 mV vs. saturated calomel electrode (SCE) for the corrosion potential and 13.4 μA·cm-2 for the corrosion current density. The calculated value for the corrosive attack protection efficiency is 67.7%

Characterisation of a Novel Complex Concentrated Alloy for Marine Applications

Complex concentrated alloys (CCAs) are a new family of materials with near equimolar compositions that fluctuate depending on the characteristics and destination of the material. CCAs expand the compositional limits of the traditional alloys, displaying new pathways in material design. A novel light density Al5Cu0.5Si0.2Zn1.5Mg0.2 alloy was studied to determine the structural particularities and related properties. The alloy was prepared in an induction furnace and then annealed under a protective atmosphere. The resulted specimens were analysed by chemical, structural, mechanical, and corrosion resistance. The structural analyses revealed a predominant FCC and BCC solid solution structure. The alloy produced a compression strength of 500–600 MPa, comparable with conventional aluminium alloys. The corrosion resistance in 3.5% NaCl solution was 0.3424 mm/year for as-cast and 0.1972 mm/year for heat-treated alloy, superior to steel, making the alloy a good candidate for marine applications

Modeling and Characterization of Complex Concentrated Alloys with Reduced Content of Critical Raw Materials

The continuous development of society has increased the demand for critical raw materials (CRMs) by using them in different industrial applications. Since 2010, the European Commission has compiled a list of CRMs and potential consumption scenarios with significant economic and environmental impacts. Various efforts were made to reduce or replace the CRM content used in the obtaining process of high-performance materials. Complex concentrated alloys (CCAs) are an innovative solution due to their multitude of attractive characteristics, which make them suitable to be used in a wide range of industrial applications. In order to demonstrate their efficiency in use, materials should have improved recyclability, good mechanical or biocompatible properties, and/or oxidation resistance, according to their destination. In order to predict the formation of solid solutions in CCAs and provide the optimal compositions, thermodynamic and kinetic simulations were performed. The selected compositions were formed in an induction furnace and then structurally characterized with different techniques. The empirical results indicate that the obtained CCAs are suitable to be used in advanced applications, providing original contributions, both in terms of scientific and technological fields, which can open new perspectives for the selection, design, and development of new materials with reduced CRM contents

Integrated Assessment of Surface Water Quality in Danube River Chilia Branch

The Chilia branch is the north branch of the Danube River at the Romania-Ukraine border in the Danube Delta; it is a complex system with economic and ecological values. The surface water quality is a major concern and monitoring programs have been developed at the national and international level. The objective of this study was to evaluate the water quality of the Chilia branch in different sampling points from the mouth to the discharge in the Black Sea. The assessment of water quality was done at the individual level taking into account the nutrient concentrations and the standard limits for good ecological status and at integrative levels, using CCME WQI. The longitudinal distribution of Chilia branch water quality was done using GIS method. A total of 106 water samples were collected between 2013 and 2019 from five sampling points. At the individual level, the Chilia branch has a good ecological status except for its levels of total nitrogen, due to the organic nitrogen contribution in 2015. In 90% of nutrient concentrations, low values predominate and high values are considered extreme; only in 10% do high values predominate and low values are considered extreme concentrations. In equal percentages, 50% of the nutrient concentrations have a high degree of heterogeneity and the other 50% of concentration values are very close to the average values, with a high degree of homogeneity. CCME WQI method indicated that 39.93% of surface waters from the Chilia branch had an excellent quality, 45.45% a good quality, and only 14.62% a fair quality

Influence of Heat Treatment on the Corrosion Behavior of Electrodeposited CoCrFeMnNi High-Entropy Alloy Thin Films

In this paper, we investigate what effects heat treatment can have on potentiodynamically electrodeposited high-entropy thin film (HEA) CoCrFeMnNi alloys. We focused our study on the corrosion resistance in synthetic seawater, corroborated with the structure and microstructure of these thin films. Thin films of HEA alloys were deposited on a copper foil substrate, using an electrolyte based on the organic system dimethyl-sulfoxide (DMSO-(CH3)2SO)-acetonitrile (AN-CH3CN) (in a volume ratio of 4:1), which contains LiClO4 as electrolyte support and chloride salts of CoCl2, CrCl3 × 6H2O, FeCl2 × 4H2O, MnCl2 × 4H2O and NiCl2 × 6H2O. Using MatCalc PC software, based on the CALPHAD method, the structure and characteristics of the HEA system were investigated, and thermodynamic and kinetic criteria were calculated. The modeling process generated in the body-centered-cubic (BCC) or face-centered-cubic (FCC) structures a series of optimal compositions that are appropriate to be used in anticorrosive and tribological applications in a marine environment. Electrochemical measurements were carried out in an aerated artificial seawater solution at ambient temperature. In the experimental media, HEA thin films proved to have good corrosion resistance and were even better than the copper substrate. Corrosion resistance was improved after heat treatment, as shown by polarization and EIS tests. The structure and microstructure of HEA thin films before and after corrosion in artificial seawater were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The XRD data showed no significant changes in the structure of HEA heat-treated thin films after the corrosion in saline media. The data obtained by polarization and ESI are supported by results from SEM-EDS. This complex study reveals that, for HEA thin films, heat treatment leads to an increase in corrosion resistance. So, this finding suggests that thermal annealing is an appropriate method for improving the corrosion performance of HEA thin films

Polymorphisms in autophagy genes and active pulmonary tuberculosis susceptibility in Romania

Autophagy, a homeostatic process involved in nutrient regeneration and immune responses, may be involved in intracellular killing of M. tuberculosis. Several studies linked variation in autophagy genes with susceptibility to pulmonary tuberculosis, but others did not confirm these findings