Search results for "Perpendicular"
showing 10 items of 168 documents
Computer Modeling of Defects and Surfaces in Advanced Perovskite Ferroelectrics
2000
The (110) surface relaxations are calculated for SrTiO3 and BaTiO3 perovskites. The positions of atoms in 16 near-surface layers placed atop a slab of rigid ions are optimized. Strong surface rumpling and surface-induced dipole moments perpendicular to the surface are predicted for both the O-terminated and Ti-terminated surfaces. Calculated optical properties of basic point defects – F-type centres and hole polarons – in KNbO3 are used for the interpretation of available experimental data.
Droplets pinned at chemically inhomogenous substrates: A simulation study of the two-dimensional Ising case
2016
As a simplified model of a liquid nanostripe adsorbed on a chemically structured substrate surface, a two-dimensional Ising system with two boundaries at which surface fields act is studied. At the upper boundary, the surface field is uniformly negative, while at the lower boundary (a distance L apart), the surface field is negative only outside a range of extension b, where a positive surface stabilizes a droplet of the phase with positive magnetization for temperatures T exceeding the critical temperature Tw of the wetting transition of this model. We investigate the local order parameter profiles across the droplet, both in the directions parallel and perpendicular to the substrate, vary…
Adsorption of Semiflexible Polymers in Cylindrical Tubes
2021
Conformations of wormlike chains in cylindrical pores with attractive walls are explored for varying pore radius and strength of the attractive wall potential by molecular dynamics simulations of a coarse-grained model. Local quantities such as the fraction of monomeric units bound to the surface and the bond-orientational order parameter as well as the radial density distribution are studied, as well as the global chain extensions parallel to the cylinder axis and perpendicular to the cylinder surface. A nonmonotonic convergence of these properties to their counterparts for adsorption on a planar substrate is observed due to the conflict between pore surface curvature and chain stiffness. …
Effect of kinks and concerted diffusion mechanisms on mass transport and growth on stepped metal surfaces
1997
Abstract We study the effect of kinks and concerted atomic mechanisms on diffusion processes relevant to metal-on-metal homoepitaxy on fcc metal surfaces vicinal to the fcc (100) direction. First, we carry out extensive finite-temperature molecular dynamics simulations based on the effective medium theory to search for diffusion mechanisms that dominate the mass transport perpendicular and parallel to step edges. Then, the energetics of these processes are studied by ground state calculations. Our results show that kinks play an important role for diffusion both across and along step edges. In particular, the combined effect of kinks and concerted exchange is found to be able to remove loca…
Architecture in cortical bone and ultrasound transmission velocity
1993
The square of ultrasound transmission velocity in a material is correlated to the modulus of elasticity, which is an indicator of its mechanical properties. This might make the measurement of ultrasound transmission velocity useful in the noninvasive diagnosis of bone diseases. Bone, however, is not an isotropic material but is architecturally structured. The aim of our study was to investigate and especially to quantify the influence of architecture in cortical bone on ultrasound transmission velocity. Twenty-two rectangular, flat specimens of cortical bone were prepared from diaphysis of fresh pig radius. Ultrasound transmission velocity was measured parallel and perpendicular to directio…
Phase separation in thin films: Effect of temperature gradients
2013
We study the phase-separation kinetics of a binary (AB) mixture confined in a thin film of thickness D with a temperature gradient. Starting from a Kawasaki-exchange kinetic Ising model, we use a master-equation approach to systematically derive an extension of the Cahn-Hilliard model for this system. We study the effect of temperature gradients perpendicular to the film with "neutral" (no preference for either A or B) surfaces. We highlight the rich phenomenology and pattern dynamics which arises from the interplay of phase separation and the temperature gradient.
tert-Butyl N-benzyl-N-(4-methyl-2-pyridyl)carbamate
2008
In the crystal structure of the title compound, C18H22N2O2, the pyridine ring makes dihedral angles of 83.71 (6) and 9.2 (1)° with the phenyl ring and the carbamate plane, respectively. The phenyl ring and the carbamate plane are nearly perpendicular to one another, with a dihedral angle of 87.17 (7)°.
Pannello precompresso di vetromattoni assemblati a secco per la realizzazione di involucri traslucidi
2012
L’invenzione riguarda la realizzazione di un pannello di vetromattoni montati “a secco” -da impiegare per la realizzazione di involucri edilizi traslucidi anche nel caso di edifici alti- che è in grado di rispondere adeguatamente alle sollecitazioni orizzontali (quali quelle dovute a vento e sisma) grazie all’applicazione della tecnica della precompressione mondirezionale. Per offrire una risposta ai limiti imposti dalla tecnica di assemblaggio tradizionale dei vetromattoni (“ad umido”), l’applicazione della precompressione consente, infatti, di dare ai pannelli preassemblati “a secco” una rigidezza adeguata anche in direzione normale al loro piano di posa, sfruttando le buone caratteristic…
Application of modulated calorimetry to the Liquid metals using electromagnetic levitation and static magnetic field
2018
Measurement of the thermophysical properties of liquid metals is challenging because of their high chemical activity and high temperatures. The electromagnetic levitation allows one to hold the electrically conductive liquid sample containerless in an inert atmosphere in thermal equilibrium while measurements on the sample can be taken in a non-contact way followed by extraction of some thermophysical properties. Yet, the electromagnetic forces within the skin layer inside the sample cause convective flow of the liquid thus disabling the data extraction. A static magnetic field imposed over a sample is known to damp the convective flow. With these ideas, an experimental set-up with a DC mag…
Formation of metastable structures by phase separation triggered by initial composition gradients in thin films.
2012
Phase separation kinetics of a binary (A,B) mixture contained in a thin film of thickness D induced by a quench from the one-phase region into the miscibility gap is studied by simulations using a Cahn-Hilliard-Cook model. The initial randomly mixed state (50% A, 50% B) contains a concentration gradient perpendicular to the film, while the surfaces of the film are "neutral" (no preference for either A or B). In thermal equilibrium, a pattern of large A-rich and B-rich domains must result, separated by domain walls oriented perpendicularly to the external surfaces of the thin film. However, it is shown that for many choices of D and the strength of the initial gradient Ψ(g), instead a very l…