Search results for " Metals"
showing 10 items of 462 documents
Microscopic evidence of a flat melting curve of tantalum
2010
International audience; New data on the high-pressure melting curve of Ta up to 48GPa are reported. Evidence of melting from changes in sample texture was found in five different experiments using scanning electron microscopy. The obtained melting temperatures are in excellent agreement with earlier measurements using x-ray diffraction or the laser-speckled method but are in contrast with several theoretical calculations. The results are also compared with shock-wave data. These findings are of geophysical relevance because they confirm the validity of earlier experimental techniques that resulted in low melting slopes of the transition metals measured in the diamond-anvil cell, including i…
Bond stretching and redox behavior in coinage metal complexes of the dichalcogenide dianions [(SPh2P)2CEEC(PPh2S)2]2- (E=S, Se): diradical character …
2011
The metathetical reactions of a) [Li(tmeda)](2)[(S)C(PPh(2)S)(2)] (Li(2)·3c) with CuCl(2) and b) [Li(tmeda)](2)[(SPh(2)P)(2)CSSC(PPh(2)S)(2)] (Li(2)·4c) with two equivalents of CuCl both afford the binuclear Cu(I) complex {Cu(2)[(SPh(2)P)(2)CSSC(PPh(2)S)(2)]} (5c). The elongated (C)S-S(C) bond (ca. 2.54 and 2.72 A) of the dianionic ligand observed in the solid-state structure of 5c indicate the presence of diradical character as supported by theoretical analyses. The treatment of [Li(tmeda)](2)[(SPh(2)P)(2)CSeSeC(PPh(2)S)(2)] (Li(2)·4b) and Li(2)·4c with AgOSO(2)CF(3) produce the analogous Ag(I) derivatives, {Ag(2)[(SPh(2)P)(2)CEEC(PPh(2)S)(2)]} (6b, E=Se; 6c, E=S), respectively. The disele…
Interplay of spin-dependent delocalization and magnetic anisotropy in the ground and excited states of [Gd2@C78]− and [Gd2@C80]−
2017
The magnetic properties and electronic structure of the ground and excited states of two recently characterized endohedral metallo-fullerenes, [Gd2@C78]- (1) and [Gd2@C80]- (2), have been studied by theoretical methods. The systems can be considered as [Gd2]5+ dimers encapsulated in a fullerene cage with the fifteen unpaired electrons ferromagnetically coupled into an S = 15/2 high-spin configuration in the ground state. The microscopic mechanisms governing the Gd-Gd interactions leading to the ferromagnetic ground state are examined by a combination of density functional and ab initio calculations and the full energy spectrum of the ground and lowest excited states is constructed by means …
Environmental effects and potential impact on human health caused by the recent Nyiragongo eruption (Democratic Republic of Congo)
2022
Volcanic activity emits large amounts of gases and particles to the atmosphere subsequently spreading contaminants to rain, surface waters and soils, negatively impacting on the environment and the human health. The recent eruption of Nyiragongo occurred on 22nd of May, injected large quantities of ash affecting the environment of the Virunga area, and more than 2 million people living between 18-25 km far from the main crater of Nyiragongo. Several studies demonstrated that drinking waters and plants may contain high contents of natural pollutants, and when ingested they become harmful to human health causing acute or chronic diseases. In this study, we investigated the impact of the recen…
Dense drug-eluting biodegradable Fe-Ag nanocomposites
2021
Abstract Biodegradable metals in orthopedics are aimed to eliminate secondary the surgical intervention for implant removal, and thus improve patient compliance, reduce surgery costs and the risk of infections. In addition, biodegradable implants could be loaded with different drugs to prevent the growth of pathogens and the development of bone infections, kill remaining cancer cells after tumor resection or stimulate bone regeneration. However, drugs undergo thermal decomposition under the conditions of conventional metal fabrication processes. In this work, we describe the fabrication of a dense drug-eluting biodegradable Fe-Ag nanocomposite containing 10 vol% of Ag and loaded with the an…
Atmospheric Lead Deposition into Guarapina Lagoon, Rio de Janeiro State, Brazil
1988
The rate of anthropogenic mobilization of heavy metals is higher than the natural supply to the sedimentary environments. I n rivers, lakes and various other terrestrial areas, the drastic increase of heavy metals has been accredited to human activity (Tyler 1972). Erlenkeuser et al. (1974) suggest that Cd, Pb, Zn and Cu in the upper sediment sequence of sediment cores collected from Kiel Bight in the Baltic Sea, are the result of fossil fuel use in industries. Such assemblages have been identified in North America by Goldberg et al. (1977, 1979) from both coastal regions. Sediment cores taken from the deepest part of lakes and lagoons have been analysed to study the historical development …
Byproduct production of minor metals: Threat or opportunity for the development of clean technologies? The PV sector as an illustration
2013
Abstract Today, the fight against global warming and the coming hydrocarbon exhaustion involve a drastic increase of clean energies. These technologies resort to many minor metals which are byproduct of major metals. We will take the definition of Hageluken and Mesker (2010, Complex Life Cycles of Precious and Special Metals. In: Edition Thomas E. Graedel, Ester van der Voet (Eds.), Strungmann Forum Report, Linkages of Sustainability, MIT Press) to show precisely what minor metals are: “[they are] metals that have relatively low production or usage, which occur in low ore concentrations, are regarded as rare, or are not traded at major public exchanges”. We will analyze the byproduct status…
Peculiarities of Phase Formation in Mn-Based Na SuperIonic Conductor (NaSICon) Systems: The Case of Na1+2xMnxTi2–x(PO4)3 (0.0 ≤ x ≤ 1.5)
2021
This project has received funding from the European Regional Development Fund (Project no. 01.2.2-LMT-K-718-02–0005) under grant agreement with the Research Council of Lithuania (LMTLT). We thank the High Performance Computing Center “HPC Saulėtekis” at the Faculty of Physics, Vilnius University, for the use of computational resources.
Electric control of the spin Hall effect by intervalley transitions
2013
Controlling spin-related material properties by electronic means is a key step towards future spintronic technologies. The spin Hall effect (SHE) has become increasingly important for generating, detecting and using spin currents, but its strength-quantified in terms of the SHE angle-is ultimately fixed by the magnitude of the spin-orbit coupling (SOC) present for any given material system. However, if the electrons generating the SHE can be controlled by populating different areas (valleys) of the electronic structure with different SOC characteristic the SHE angle can be tuned directly within a single sample. Here we report the manipulation of the SHE in bulk GaAs at room temperature by m…
Hydrothermal aging of carbon reinforced epoxy laminates with nanofibrous mats as toughening interlayers
2016
Electrospun mats have been applied as toughening interlayers in high performance carbon fiber epoxy composites. While the toughening mechanism exerted by the mat at the interface is the subject of several recent studies, no investigations are reported on the aging behaviour of laminates comprising these nanostructured elements. This work investigates the influence of the combined effect of water and temperature (90 °C) on laminates with Nylon 6,6 electrospun membranes placed either at the middle plane only or at each interlayer. The water-uptake behaviour is modelled by a two-stage diffusion model and compared with the behaviour of the neat resin and of the laminate without mats. Interestin…