Search results for "ODS"

AB INITIO CALCULATIONS OF SrTiO3, BaTiO3, PbTiO3, CaTiO3 AND BaZrO3 (001) AND (011) SURFACES

2009

I present results of calculations of surface relaxations and rumplings for the (001) and (011) surfaces of BaZrO3 and ATiO3 perovskites (A = Sr, Ba, Pb and Ca) using a hybrid B3PW description of exchange and correlation. The (001) surface energies of AO, TiO2 and ZrO2 terminations are found to be comparable with each other for all five materials. The surface energies for BaZrO3, SrTiO3, BaTiO3, PbTiO3 and CaTiO3 (011) surfaces for all terminations are considerably larger than for (001) surfaces. We predict a considerable increase in the Ti-O (Zr-O) chemical bond covalency near the (011) surface as compared both to the bulk and to the (001) surface.

Experimental research regarding the study of surface quality of aluminum alloys processed through milling

2017

The aim of this paper is to present the necessary steps to conduct a design of experiment with application on the aluminum alloy surface quality obtained by end-milling process. The machined surface quality is influenced by the cutting process parameters, and especially by their variation. The research methods used in this paper are the Taguchi method - to determine the cutting parameters influence, on the surface quality, and the full factorial design of experiment to confirm the results obtained by Taguchi’s method and to determine the percentage of the parameters influence involved in the process.

Theoretical Simulations of Surface Relaxation for Perovskite Titanates

2000

The (100) and (110) surface relaxations are calculated for SrTiO3 and BaTiO3 perovskite thin films Using a semiempirical shell model, the positions of atoms in 16 near-surface layers placed atop a slab of rigid ions are calculated. Surface rumpling and surface-induced dipole moments perpendicular to the surface are calculated for different surface terminations. Surface relaxation is found much larger for the (110) surface. Our results for the (100) surfaces are compared with ab initio calculations and LEED experiments.

Ab initio calculations for the polar (0 0 1) surfaces of YAlO3

2018

Abstract The results of ab initio calculations of polar YAlO3 (0 0 1) surfaces by means of a hybrid B3LYP exchange-correlation functional as it is implemented in the CRYSTAL computer code are presented. Both polar YO and AlO2-terminations of the cubic YAlO3 (0 0 1) surface were considered. We performed relaxation of atoms on the upper three layers of both YO and AlO2-terminated YAlO3 (0 0 1) surfaces using in our calculations slabs containing 22 and 23 atoms as well as 9 layers, respectively. We predict a significant increase of the Al-O chemical bond covalency on the AlO2-terminated YAlO3 (0 0 1) surface with respect to the YAlO3 bulk. Our calculated YO and AlO2-terminated YAlO3 polar (0 0…

Engineering Proteins at Interfaces: From Complementary Characterization to Material Surfaces with Designed Functions

2018

Abstract Once materials come into contact with a biological fluid containing proteins, proteins are generally—whether desired or not—attracted by the material's surface and adsorb onto it. The aim of this Review is to give an overview of the most commonly used characterization methods employed to gain a better understanding of the adsorption processes on either planar or curved surfaces. We continue to illustrate the benefit of combining different methods to different surface geometries of the material. The thus obtained insight ideally paves the way for engineering functional materials that interact with proteins in a predetermined manner.

Molecular surface area and hydrophobic effect.

1992

Land surface emissivity retrieval from satellite data

2012

As an intrinsic property of natural materials, land surface emissivity LSE is an important surface parameter and can be derived from the emitted radiance measured from space. Besides radiometric calibration and cloud detection, two main problems need to be resolved to obtain LSE values from space measurements. These problems are often referred to as land surface temperature LST and emissivity separation from radiance at ground level and as atmospheric corrections in the literature. To date, many LSE retrieval methods have been proposed with the same goal but different application conditions, advantages, and limitations. The aim of this article is to review these LSE retrieval methods and to…

Applying Experimental Research Management to a Technological Process using Taguchi's Method

2018

Abstract The surface quality is dependent on certain cutting process parameters that can vary, causing variations on the surface roughness. The main subject of this paper focuses on the experimental research management applied to a technological process whose final purpose was to determine an equation of the surface roughness depending on the process parameters, obtained by the Al7136 end milling process. The research method used in this paper is the Taguchi's method. According to the research management steps, in order to perform the experimental determination of the surface roughness, an experimental stand used to determine the objective function was presented. The surface roughness equat…

Surface and volume non-invasive methods for the structural monitoring of the bass-relief ‘Madonna con Bambino’ (Gorizia, Northern Italy)

2016

Structural analysis of marble statues, carried out by non-invasive and in situ methods, is crucial to define the state of conservation of the artworks and to identify the deterioration phenomena that can affect them. In this work, we combined in situ non-destructive techniques, ultrasonic tomography (US), ultraviolet-induced visible fluorescence (UV-IF) and X-ray fluorescence (XRF) to study the bass-relief ‘Madonna con Bambino’ (Gorizia, Italy). The US revealed the presence of some metallic pivots, associated with areas of high sound velocity; moreover, a more degraded area has been identified in the lower part of the bass-relief. The acquired UV-IF image confirmed the presence of surface d…

Enhanced Thermal Stability of Gold and Silver Nanorods by Thin Surface Layers

2007

Using in situ transmission electron microscopy, we find that a carbon shell governs the morphological transitions of gold and silver nanorods upon heating. Encapsulated Ag nanorods show a surprising nonuniform sublimation behavior starting from one side and leaving behind the shell. Uncovered gold nanorods transform their shape to spheres well below the bulk melting temperature through surface diffusion, which is prevented by a thin carbon shell.