A century of human interventions on sediment flux variations in the Danube-Black Sea transition zone

Many deltas around the world have recorded a decreasing sediment input, mostly due to retention in dams constructed on the river or in the river basin. The Danube River has recorded a significant decrease of its sediment supply to the Danube Delta and the NW Black Sea. This study uses 210Pb and 137Cs dating, to investigate the effects of the decreasing sediment flux in lakes, lagoons, delta front and prodelta area. Both the effects of the Iron Gate I and II dams and other local factors are discussed. These results define the period of 1960-1990 as the ‘major anthropic interventions period’ in the Danube Delta. Results show a decrease in siliciclastic flux, especially in lakes, the Sahalin lagoon and the prodelta area and a general increase in the Musura lagoon and the delta front area. Sand content is also shown to decrease in most areas and is replaced by silt. The changes in sediment accumulation rates depend mostly on the hydrological connectivity of the area and the local hydrotechnical works. Overall, the local anthropic interventions in the delta affect sediment flux in the subaerial delta and the delta front, while the prodelta is affected by the overall decrease caused by interventions in the river basin. This study can contribute to improving management strategies in the area and to a better understanding of future research needs in the Danube Delta-Black Sea system

New complexes of Co(II), Ni(II), Cu(II) with Schiff base N,N’-bis-(3-methoxy-saliciliden)-3,3’-dimethylbenzidine

The new N,N’-bis-(3-methoxy-saliciliden)-3,3’-dimetilbenzidine (H2L) Schiff base and complexes with Co(II), Ni(II) and Cu(II) of type [M(HL)Cl(H2O)] (M=Co(II), Cu(II)) [M2L(H2O)4]X2 (M=Co(II), X=ClO4 and M=Cu(II), X=NO3) and [M2L(CH3COO)2] (M=Co(II), Ni(II), Cu(II)) were synthesised. The ligand and complexes were characterized by elemental analysis, conductibility measurements, magnetic moments at room temperature, IR, NMR, UV-VIS-NIR, EPR spectra and thermogravimetric analysis. A molar ratio of 1:1 or 1:2 between ligand and metal was determined from the elemental analysis. Except for perchlorate complex that behave as electrolyte, the rest of complexes are non-electrolytes. The spectral data suggest a tetrahedral, pseudo-tetrahedral or square-planar stereochemistry respectively, data confirmed by magnetic behaviour of complexes. The antimicrobial tests indicate a fungicide effect both for ligand and complexes

Monte Carlo Simulations of the Magnetic Behavior, Ordering Temperature and Magnetocaloric Effects in 1D, 2D and 3D Ferrimagnetic Systems

As for the systematic investigations of magnetic behaviors and its related properties, computer simulations in extended quantum spin networks have been performed in good conditions via the generalized Ising model using the Monte Carlo-Metropolis algorithm with proven efficiencies. The present work, starting from a real magnetic system, provides detailed insights into the finite size effects and the ferrimagnetic properties in various 1D, 2D and 3D geometries such as the magnetic moment, ordering temperature, and magnetocaloric effects with the different values of spins localized on the different coordinated sites

Polynuclear coordination precursor compounds for M3Fe5O12 garnets (M = Y, Eu, Gd and Er).

A new type of complexes compounds (NH4)6[M3Fe5(C4O5H4)6(C4O5H3)6]·16H2O (where M(III) = Y, Eu, Gd, Er), (NH4)6[M3Fe5(C4O6H4)6(C4O6H3)6]·16H2O (where M(III) = Gd, Er) and (NH4)6[M3Fe5(C6O7H10)6(C6O7H9)6]·xH2O (where M(III) = Y; x = 8; M(III) = Eu, Er; x = 22) [C4O5H42– = malate anion; C4O6H42– = tartarate anion, C6O7H11– = gluconate anion] have been synthesized and characterised by elemental chemical analysis and physico-chemical measurements (IR, UV-Vis spectroscopy and magnetic determinations). The synthetic possibilities offered by the use of these new compounds as potential precursors for garnets have been suggested

Alkoxo-bridged copper( ii ) complexes as nodes in designing solid-state architectures. The interplay of coordinative and d 10 –d 10 metal–metal interactions in sustaining supramolecular solid-state architectures

International audienc

Polynuclear coordination compounds as precursors for CuFe2O4

The possibility of obtaining copper ferrite through the thermal decomposition of the two polynuclear coordination compounds: (NH4)8[Fe2Cu(C2O4)8] (I) and [Fe2Cu(C2O4)2(OH)4]*4H2O (II) was considered. The polynuclear compounds were characterized by various physical chemical techniques, e.g., IR, UV-VIS, EPR, Mössbauer spectra, thermal analysis and magnetic measurements. The final products obtained after thermal decomposition of the complex compounds were analysed by X-ray diffraction. A mixture of tetragonal CuFe2O4, α-Fe2O3 and CuO is generated from the thermolysis of compound I, while a clean tetragonal CuFe2O4 with saturation magnetization of 26.89 emu g−1 is obtained from compound II

Polynuclear coordination compounds as precursors for CuFe2O4

The possibility of obtaining copper ferrite through the thermal decomposition of the two polynuclear coordination compounds: (NH4)8[Fe2Cu(C2O4)8] (I) and [Fe2Cu(C2O4)2(OH)4]*4H2O (II) was considered. The polynuclear compounds were characterized by various physical chemical techniques, e.g., IR, UV-VIS, EPR, Mössbauer spectra, thermal analysis and magnetic measurements. The final products obtained after thermal decomposition of the complex compounds were analysed by X-ray diffraction. A mixture of tetragonal CuFe2O4, α-Fe2O3 and CuO is generated from the thermolysis of compound I, while a clean tetragonal CuFe2O4 with saturation magnetization of 26.89 emu g−1 is obtained from compound II