591 research outputs found
Multiscale modelling of drug-polymer nanoparticle assembly identifies parameters influencing drug encapsulation efficiency
Using a multiscale (dual resolution) approach combining an atomistic (GROMOS96) and coarse-grain (MARTINI) force field, we have been able to simulate the process of drug-polymer nanoparticle assembly by nanoprecipitation from mixed solvents. Here we present the development and application of this method to the interaction of three poly(glycerol adipate) polymer variants with the anti-cancer drug dexamethasone phosphate. Differences in encapsulation efficiency and drug loading between the polymers are in agreement with the experimental trend. Reference atomistic simulations at key points along the predicted aggregation pathway support the accuracy of the much more compute-efficient multiscale methodology
Probing the Gas-Phase Dynamics of Graphene Chemical Vapour Deposition using <i>in-situ</i> UV Absorption Spectroscopy
AbstractThe processes governing multilayer nucleation in the chemical vapour deposition (CVD) of graphene are important for obtaining high-quality monolayer sheets, but remain poorly understood. Here we show that higher-order carbon species in the gas-phase play a major role in multilayer nucleation, through the use of in-situ ultraviolet (UV) absorption spectroscopy. These species are the volatilized products of reactions between hydrogen and carbon contaminants that have backstreamed into the reaction chamber from downstream system components. Consequently, we observe a dramatic suppression of multilayer nucleation when backstreaming is suppressed. These results point to an important and previously undescribed mechanism for multilayer nucleation, wherein higher-order gas-phase carbon species play an integral role. Our work highlights the importance of gas-phase dynamics in understanding the overall mechanism of graphene growth.</jats:p
Copper Oxidation through Nucleation Sites of Chemical Vapor Deposited Graphene
We investigate the nucleation defect-triggered
oxidation of Cu
covered by CVD graphene during postannealing in air. The results reveal
that different growth conditions may induce imperfect nucleation of
graphene, and cause creation of defects near the nucleation point
such as pin holes and amorphous carbon. These defects would serve
as a pathway for the diffusion of O<sub>2</sub> during thermal annealing,
allowing oxidation of Cu to progress gradually from the nucleation
center toward the growth edge. The oxidation process follows the graphene
morphology closely; the shape of the oxidized area of Cu has a striking
resemblance to that of the graphene flakes. Our work demonstrates
that inferior graphene nucleation in CVD processes can compromise
the oxidation resistance of a graphene-coated Cu substrate, and indirectly
reveal the structure and integrity of graphene, which is of fundamental
importance for the quality monitoring and control of graphene growth,
for understanding the mechanisms of graphene nucleation and growth,
and has implications for graphene’s use in electronic and passivation
applications
Recent Results from the CP-PACS Collaboration
We present an overview of recent results from the CP-PACS computer on the
quenched light hadron spectrum and an on-going two-flavour full QCD study. We
find that our quenched hadron mass results are compatible with the mass
formulae predicted by quenched chiral perturbation theory, which we adopt in
our final analysis. Quenched hadron masses in the continuum limit show
unambiguous and systematic deviations from experiment. For our two-flavour full
QCD simulation we present preliminary results on the light hadron spectrum,
quark masses and the static potential. The question of dynamical sea quark
effects in these quantities is discussed.Comment: LATTICE98, plenary talk, LaTeX(espcrc2.sty), 13 pages, 23 figure
Leptonic Decays of Heavy-Light Systems
Results from recent lattice calculations of the decay constants and
are reviewed. A discussion of the methods currently used is presented,
together with an outline of the various systematic effects involved.Comment: Plenary talk given at LAT95, Melbourne, July 1995. 12 pages (Two
column format), Latex file with 2 postscript figures uuencoded. Requires
psfig.sty and espcrc2.sty [Numbers in Table 4 from LANL Collaboration updated
slightly.
Semileptonic Decays: an Update Down Under
Heavy-meson semileptonic decays calculations on the lattice are reviewed. The
focus is upon obtaining reliable matrix elements. Errors that depend upon the
lattice spacing, , are an important source of systematic error. Full
improvement of matrix elements for arbitrary-mass four-component quarks is
discussed. With improvement, bottom-quark matrix elements can be calculated
directly using current lattices. Momentum dependent errors for -improved
quarks and statistical noise limit momenta to around 1 GeV/c with current
lattices. Hence, maximum recoil momenta can be reached for decays while
only a fraction of the maximum recoil momentum can be reliably studied for the
light-meson decay modes of the . Differential decay rates and partial widths
are phenomenologically important quantities in decays that can be reliably
determined with present lattices.Comment: 14 pages, 9 postscript figures, requires espcrc2.st
Quantitative optical mapping of two-dimensional materials
The pace of two-dimensional materials (2DM) research has been greatly accelerated by the ability to identify exfoliated thicknesses down to a monolayer from their optical contrast. Since this process requires time-consuming and error-prone manual assignment to avoid false-positives from image features with similar contrast, efforts towards fast and reliable automated assignments schemes is essential. We show that by modelling the expected 2DM contrast in digitally captured images, we can automatically identify candidate regions of 2DM. More importantly, we show a computationally-light machine vision strategy for eliminating false-positives from this set of 2DM candidates through the combined use of binary thresholding, opening and closing filters, and shape-analysis from edge detection. Calculation of data pyramids for arbitrarily high-resolution optical coverage maps of two-dimensional materials produced in this way allows the real-time presentation and processing of this image data in a zoomable interface, enabling large datasets to be explored and analysed with ease. The result is that a standard optical microscope with CCD camera can be used as an analysis tool able to accurately determine the coverage, residue/contamination concentration, and layer number for a wide range of presented 2DMs
- …