Search results for "Surfaces"
showing 10 items of 2837 documents
The electronic and atomic structure of SrTiO3, BaTiO3, and PbTiO3(001) surfaces: Ab initio DFT/HF hybrid calculations
2005
In our first-principles study, the electronic properties of the (001) surfaces of three key perovskite crystals, namely SrTiO"3 (STO), BaTiO"3 (BTO), and PbTiO"3 (PTO), have been calculated by means of the density functional theory (DFT) using the exchange-correlation functional containing ''hybrid'' of the non-local Hartree-Fock (HF) exchange, DFT exchange, and Generalized Gradient Approximation (GGA) correlation functionals, commonly known as B3PW. Such a technique allows us to get the optical bulk band gap very close to experiment unlike previous calculations of perovskites. Special attention is paid to careful calculations of the surface rumpling and change of the distances between thre…
Competition between surface reaction and diffusion of gold deposited onto ZrTe3
2003
Abstract Surface reaction and diffusion of gold, deposited onto the (0 0 1) ZrTe 3 van der Waals (vdW) surface, is studied by transmission electron and scanning tunneling microscopy. It is shown that both processes compete at temperatures as low as room temperature. In case of diffusion the deposited gold mostly disappears from the surface and intercalates into the vdW gaps of the substrate. Residual unreacted gold agglomerates are rather mobile and are often displaced by the scanning tip along the [1 0 0] direction of the substrate. In case of reaction, which usually takes place at somewhat higher substrate temperatures, grains of Zr 3 Te 2 , AuTe 2 and/or Au 2 Te 3 are formed. Contrary to…
Thermal Flux through a Surface of n-Octane. A Non-equilibrium Molecular Dynamics Study
2004
We show using non-equilibrium molecular dynamics that there is local equilibrium in the surface when a two-phase fluid of n-octane is exposed to a large temperature gradient (10 8 K/m). The surface is defined according to Gibbs, and the transport across the surface is described with non-equilibrium thermodynamics. The structure of the surface in the presence of the gradient is the same as if the interface was in equilibrium, as measured by the variation across the surface of the pressure component that is parallel to the surface. The surface is in local equilibrium by this criterion and because the equation of state for the surface was unaltered by a large heat flux. The surface has a small…
The mechanism of aquaporin inhibition by gold compounds elucidated by biophysical and computational methods
2017
The inhibition of water and glycerol permeation via human aquaglyceroporin-3 (AQP3) by gold(iii) complexes has been studied by stopped-flow spectroscopy and, for the first time, its mechanism has been described using molecular dynamics (MD), combined with density functional theory (DFT) and electrochemical studies. The obtained MD results showed that the most effective gold-based inhibitor, anchored to Cys40 in AQP3, is able to induce shrinkage of pores preventing glycerol and water permeation. Moreover, the good correlation between the affinity of the Au(iii) complex to Cys binding and AQP3 inhibition effects was highlighted, while no influence of the different oxidative character of the c…
New frontiers in sustainable energy production and storage
2015
Evidently, one of the most effective ways to reduce CO2 emissions consists in the deployment of renewable energies, with the advantage of securing and expanding the energy supplies of a given country. The main problem that arises is due to the intermittent temporary character of many renewable resources like solar and wind. For this reason, it has been recently concluded that in case of high integration of renewables into the distribution grid (more than about 30% of the electricity mix), the implementation of energy storage systems together with smart grids is necessary. Therefore, renewable energies for large scale power production in country would usually require the availability of a su…
Cooperative Thermal and Optical Switching of Spin States in a New Two-Dimensional Coordination Polymer
2003
{Fe(pmd)2[Cu(CN)2]2} (pmd = pyrimidine) displays a rigid two-dimensional structure and undergoes thermal- and optical-driven spin crossover behaviour; cooperative elastic coupling between iron(II) ions in the framework induces thermal hysteresis in the HS↔LS conversion and sigmoidal HS→LS relaxation of the photo-induced HS state at low temperatures. Niel, Virginie, Virginie.Niel@uv.es ; Galet Domingo, Ana Guadalupe, Ana.Galet@uv.es ; Gaspar Pedros, Ana Belen, Ana.B.Gaspar@uv.es ; Real Cabezos, Jose Antonio, Jose.A.Real@uv.es
Characterization of V-doped SnO2 nanoparticles at ambient and high pressures
2018
Nanoparticles of V-doped SnO2 with stoichiometry Sn1-xO2Vx (x = 0.05, 0.075, 0.125) have been synthesized by a co-precipitation method. Their structural, vibrational, and nuclear properties have been characterized by x-ray Diffraction, Transmission Electron Microscopy, Energy Dispersive x-ray Spectroscopy, Raman Spectroscopy, and Mössbauer Spectroscopy (with 119Sn probe) at ambient pressure. We also performed high-pressure synchrotron x-ray diffraction experiments. The structural behaviour was studied up to ∼10 GPa under quasi-hydrostatic conditions. It has been found that tin dioxide nanoparticles with V are more compressible than un-doped tin dioxide nanoparticles. Fil: Ferrari, S. Consej…
3D photonic crystal intermediate reflector for micromorph thin-film tandem solar cell
2008
The concept of 3D photonic intermediate reflectors for micromorph silicon tandem solar cells has been investigated. In thin-film silicon tandem solar cells consisting of amorphous and microcrystalline silicon with two junctions of a-Si/μc-Si, efficiency enhancements can be achieved by increasing the current density in the a-Si top cell. It is one goal to provide an optimized current matching at high current densities. For an ideal photon-management between top and bottom cell, a spectrally selective intermediate reflective layer (IRL) is necessary, which is less dependent of the angle of incidence than state-of-the-art thickness dependent massive interlayers. The design, preparation and cha…
Film blowing of silane-modified polyethylene
2009
The grafting of vinyltriethoxysilane (VTES) onto polyethylene (PE) with the help of small amounts of peroxides was investigated to film-blow these modified materials. The degree of crosslinking was kept very low to achieve good melt processability and improved mechanical properties. The possibility of obtaining modified PE films with improved properties and regularly distributed crosslinking with a single processing step demonstrates the uniqueness of this study. The additive concentration was established through preliminary studies; with a batch mixer, it was possible to process the modified PE in the film-blowing operation. Water treatment of the modified films after film blowing allowed …
Structure-property relationships of polycarbonate diol-based polyurethanes as a function of soft segment content and molar mass
2014
Segmented thermoplastic polyurethanes (PUs) have been synthesized with polycarbonate diol as soft segment and 4,4′-diphenylmethane diisocyanate and butanediol as hard segment. Two different series employing two different soft-segment molar mass, 1000 and 2000 g/mol, and by changing the hard-segment content from 32 to 67% have been investigated with the aim to elucidate the effect of the different content variations on the properties. Morphological, thermal, and mechanical properties have been studied by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), wide angle X-ray diffraction, atomic force microscopy, tensile and…