35 research outputs found
ITER Fast Ion Collective Thomson Scattering: Detailed integrated design of the collective Thomson scattering (CTS) system for ITER
High-dimensional quantum dynamics of adsorption and desorption of H at Cu(111)
We performed high-dimensional quantum dynamical calculations of the
dissociative adsorption and associative desorption of hydrogen on Cu(111). The
potential energy surface (PES) is obtained from density functional theory
calculations. Two regimes of dynamics are found, at low energies sticking is
determined by the minimum energy barrier, at high energies by the distribution
of barrier heights. Experimental results are well-reproduced qualitatively, but
some quantitative discrepancies are identified as well.Comment: 4 two column pages, revtex, 4 figures, to appear in Phys. Rev. Let
Dynamical Quantum Processes of Molecular Beams at Surfaces: Dissociative Adsorption of Hydrogen on Metal Surfaces
Due to the improvement of computer power and the development of efficient
algorithms it is now possible to combine high-dimensional quantum dynamical
calculations of the dissociative adsorption of molecular beams with reliable
ab-initio potential energy surfaces (PES). In this brief review two recent
examples of such studies of the systems H_2/Cu(111), where adsorption is
hindered by a noticeable energy barrier, and H_2/Pd(100), where activated as
well as non-activated paths to adsorption exist, are presented. The effect of
lateral surface corrugations on the sticking probability in the tunneling and
the classical regime and the role of additional parallel momentum are discussed
in the context of the H_2/Cu(111) results. For the system H_2/Pd(100) it is
shown that the initial decrease of the sticking probability with increasing
kinetic energy, which is usually attributed to a precursor mechanism, can be
explained by dynamical steering. In addition, the influence of rotation on the
adsorption and desorption dynamics is examined.Comment: RevTeX, 22 pages, 6 figure
Six-Dimensional Quantum Dynamics of Adsorption and Desorption of H_2 at Pd(100): No Need for a Molecular Precursor Adsorption State
We report six-dimensional quantum dynamical calculations of dissociative
adsorption and associative desorption of the system H_2/Pd(100) using an
ab-initio potential energy surface. We focus on rotational effects in the
steering mechanism, which is responsible for the initial decrease of the
sticking probability with kinetic energy. In addition, steric effects are
briefly discussed.Comment: RevTeX, 11 pages, 4 figure
Robust estimation of bacterial cell count from optical density
Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data