Search results for "physisorption"
showing 10 items of 53 documents
Ten Facets, One Force Field: The GAL19 Force Field for Water - Noble Metal Interfaces
2020
<div>Understanding the structure of the water/metal interfaces plays an important role in many are as ranging from surface chemistry to environmental processes. Due to their intrinsic complexity, the water/metal interfaces cannot yet be adequately described by quantum mechanical approaches and accurate force-fields are therefore needed. We develop and parametrize GAL19, a novel force-field to describe the interaction of water with two facets (111 and 100) of five metals (Pt, Pd, Au, Ag, Cu). To increase transferability compared to its predecessor GAL17, the water-metal interaction is described as a sum of pair-wise terms. The interaction energy has three contributions: (i) physisorption …
Theoretical demonstration of the potentiality of boron nitride nanotubes to encapsulate anticancer molecule.
2015
Anticancer drug transport is now becoming an important scientific challenge since it would allow localizing the drug release near the tumor cell, avoiding secondary medical effects. We present theoretical results, based on density functional theory and molecular dynamics simulations, which demonstrate the stability of functionalized single (10,10) boron nitride nanotubes (BNNTs) filled with anticancer molecule such as carboplatin (CPT). For this functionalized system we determine the dependence of the adsorption energy on the molecule displacement near the inner BNNTs surface, together with their local morphological and electrical changes and compare the values to the adsorption energy obta…
MP2 Study of Physisorption of Molecular Hydrogen onto Defective Nanotubes: Cooperative Effect in Stone–Wales Defects
2016
We use large-scale MP2 calculations to investigate the physisorption of molecular hydrogen on (9,0) defective carbon nanotubes (CNTs) of C72H18. These large (supra)molecular systems are typically studied using conventional DFT methods, which do not describe well the van der Waals interactions responsible for this process. Here we use CCSD(T)-calibrated MP2 calculations to estimate binding energies by considering four defective structures (hydrogenated divacancy, octagon-pentagon, and two Stone-Wales defects). The largest physisorption energies for the nondefective CNT are for configurations in which H2 points toward the center of one ring. The computed interaction energies for defect-free C…
Kinetic and equilibrium studies for the adsorption of acid nucleic bases onto K10 montmorillonite
2011
Abstract The kinetic of the adsorption of two nucleic acid bases, namely adenine (A) and cytosine (C), on K10 montmorillonite (MMT) clay has been investigated over a wide range of nitrogenous bases concentrations, by using the spectrophotometric method. The measurements have been performed at T = 25.0 °C and pH = 4.0 where adenine and cytosine exist both in their protonated and neutral forms. Preliminary to the kinetic data treatment, the adsorption isotherms have been gathered and, then, analyzed by using the Freundlich and the Dubinin–Radushkevich model. The obtained results allow to draw the conclusion that physisorption of adenine and cytosine on MMT occurs and the process is mainly gov…
N2monolayers physisorbed on graphite: the herringbone transition revisited
1994
Monte Carlo simulations were undertaken of the orientational herringbone phase transition of N2 adsorbed on graphite in the complete monolayer (✓3 × ✓3) R30° structure. The non-universal aspects (c...
Diffusive motions in HD films physisorbed on graphite
2003
Abstract High-resolution quasielastic neutron scattering was used to study diffusive motions in two-dimensional liquid and solid phases of deuterium hydride submonolayers adsorbed on graphite (Papyex). For the first time it could be unambiguously clarified that the novel reentrant fluid phase at the commensurate–incommensurate transition has the character of a viscous fluid.
Superheavy element flerovium (element 114) is a volatile metal.
2014
The electron shell structure of superheavy elements, i.e., elements with atomic number Z ≥ 104, is influenced by strong relativistic effects caused by the high Z. Early atomic calculations on element 112 (copernicium, Cn) and element 114 (flerovium, Fl) having closed and quasi-closed electron shell configurations of 6d(10)7s(2) and 6d(10)7s(2)7p1/2(2), respectively, predicted them to be noble-gas-like due to very strong relativistic effects on the 7s and 7p1/2 valence orbitals. Recent fully relativistic calculations studying Cn and Fl in different environments suggest them to be less reactive compared to their lighter homologues in the groups, but still exhibiting a metallic character. Expe…
Selective chemisorption of carbon monoxide by organic-inorganic hybrid materials incorporating cobalt(III) corroles as sensing components.
2007
Twenty-one hybrid materials incorporating cobalt(III) corrole complexes were synthesized by a sol–gel process or by grafting the metallocorrole onto a mesostructured silica of the SBA-15 type. All the materials show an almost infinite selectivity for carbon monoxide with respect to dinitrogen and dioxygen in the low-pressure domain where the chemisorption phenomenon is predominant. This peculiar property is of prime importance for an application as a CO sensor. The selectivity slightly decreases at high pressures where nonselective physisorption phenomena mainly occur. The percentage of active sites for CO chemisorption ranges from 22 to 64 %. This low percentage may be attributable to inte…
Surface Characteristics Control the Attachment and Functionality of (Chimeric) Avidin
2018
The physical adsorption (physisorption) of proteins to surfaces is an important but incompletely understood factor in many biological processes and is of increasing significance in bionanotechnology as well. Avidin is an important protein because of strong avidin–biotin binding, which has been exploited in numerous applications. We have undertaken thorough experimentation on the physisorption of avidin, to chemically different flat surfaces of Si and graphite and also to the curved version of the latter, on multiwalled carbon nanotubes (MWNTs) of different diameters. The difference in the behavior of avidin on Si versus graphite is drastic; on Si, avidin deposits as single globular tetramer…
Thermogravimetric and Sorption Measurement Techniques/Instruments
2002
The survey covers commercially offered instruments for the determination of the surface structure of porous solids based on isothermal measurement of physisorption of inert gases and of thermogravimetric instruments. Basic assumptions, features and experimental uncertainties are compared.