We consider the dynamics of impact oscillators with multiple degrees of freedom subject to more than one motion limiting constraint or stop. A mathematical formulation for modelling such systems is developed using a modal approach including a modal form of the coefficient of restitution rule. The possible impact configurations for an N degree of freedom system are considered, along with definit...

An accurate description of oxygen dissociation pathways and kinetics for various local adlayer environments is key for an understanding not just of the coverage dependence of oxygen sticking, but also of reactive steady states in oxidation reactions. Density functional theory analysis for M(100) surfaces with M=Pd, Rh, and Ni, where O prefers the fourfold hollow adsorption site, does not suppor...

Ž . Monte Carlo simulations of Eley]Rideal ER mechanisms with fixed and varying Ž . sticking probabilities, p, as well as a three-step catalytic reaction TCR over fractal surfaces were performed to examine the morphological effect on the above-mentioned reactions. The effect of decay and enhancing profiles on the reaction probability Ž . distribution RPD for the ER reaction as well as effects o...

The dissociative sticking probability for H2 on Pd films supported on sputtered Highly Ordered Pyrolytic Graphite (HOPG) has been derived from measurements of the rate of the H–D exchange reaction at 1 bar. The sticking probability for H2, S, is higher on Pd hydride than on Pd (a factor of 1.4 at 140 C), but the apparent desorption energy derived from S is the same on Pd and Pd hydride within t...

It is widely accepted that planets form in protoplanetary discs. These discs, which are produced as a byproduct of stars in the collapse of a molecular cloud [23], initially consist of gas and dust, which interact with each other. The interaction induces size-dependent relative velocities between dust aggregates: the effects of Brownian motion, radial drift, vertical settling, and turbulent mix...

A microcanonical unimolecular rate theory (MURT) model incorporating quantized surface vibrations and Rice-Ramsperger-Kassel-Marcus rate constants is applied to a benchmark system for gas-surface reaction dynamics, the activated dissociative chemisorption and associative desorption of hydrogen on Cu(111). Both molecular translation parallel to the surface and rotation are treated as spectator d...

Dissolution testing is an essential requirement for the development, establishment of in vitro dissolution and in vivo performance (IVIVR), registration and quality control of solid oral dosage forms. The objective of the present study was to investigate the effect of delivery system positioning in accordance with the USP 23-recommended dissolution methods and the proposed modification on drug ...

The dissociative sticking coefficient for CH4 on Pt(111) has been measured as a function of both gas temperature (Tg) and surface temperature (Ts) using effusive molecular beam and angle-integrated ambient gas dosing methods. The experimental results are used to optimize the three parameters of a microcanonical unimolecular rate theory (MURT) model of the reactive system. The MURT calculations ...

New comb drives using high stiffness ratio springs are designed and modeled to provide capabilities of large static displacement and continuous motion for applications, such as micro XY stage, two dimensional lens scanner, variable optical attenuator, and optical switch, etc. The maximum static displacement of conventional comb drive is constrained by the side sticking effect of comb finger ele...

The NO chemisorption dynamics on ordered multilayer iron phthalocyanine (FePc) and quasiamorphous multilayer tetra-t-butyl FePc (ttbu-FePc) films on a Au(111) substrate was investigated using the King and Wells reflection technique. The NO zero coverage or initial sticking probabilities (S(0)) were measured as a function of sample temperature (T(s)) and beam energy (E(i)). The experimental resu...