1,389 research outputs found
Adsorption and desorption in confined geometries: a discrete hopping model
We study the adsorption and desorption kinetics of interacting particles
moving on a one-dimensional lattice. Confinement is introduced by limiting the
number of particles on a lattice site. Adsorption and desorption are found to
proceed at different rates, and are strongly influenced by the
concentration-dependent transport diffusion. Analytical solutions for the
transport and self-diffusion are given for systems of length 1 and 2 and for a
zero-range process. In the last situation the self- and transport diffusion can
be calculated analytically for any length.Comment: Published in EPJ ST volume "Brownian Motion in Confined Geometries
Diffusion of interacting particles in discrete geometries
We evaluate the self-diffusion and transport diffusion of interacting
particles in a discrete geometry consisting of a linear chain of cavities, with
interactions within a cavity described by a free-energy function. Exact
analytical expressions are obtained in the absence of correlations, showing
that the self-diffusion can exceed the transport diffusion if the free-energy
function is concave. The effect of correlations is elucidated by comparison
with numerical results. Quantitative agreement is obtained with recent
experimental data for diffusion in a nanoporous zeolitic imidazolate framework
material, ZIF-8.Comment: 5 pages main text (3 figures); 9 pages supplemental material (2
figures). (minor changes, published version
Differences in shell morphology and reproductive impairment in <i>Littorina littorea</i> along the Belgian coast
In this study we evaluated the condition of Littorina littorea along the Belgian coast using shell morphology and reproductive impairment (i.e. female intersex and sterility; male penis shedding) characteristics. Periwinkles were collected at eight sites along the Belgian coast of which three were in the direct vicinity of the seaports of ‘Zeebrugge’, ‘Oostende’ and ‘Nieuwpoort’. Standard shell parameters were measured, animals were sexed based on the p/a of the vesicula seminalis and reproductive impairment was determined for both sexes. Significant differences in the shell morphology and reproductive impairment could be detected among the sites. Indeed, periwinkles from ‘Zeebrugge’ were significantly larger and heavier compared to the specimens that were taken from the other sites. In addition, ‘Zeebrugge’ contained the largest number of penis shedded males (i.e. 61.11%) and intersex/sterile females (i.e. 100% and 95.24% respectively). The latter resulted in an ISI-index of 3.52, which is one of the highest ISI values ever recorded in L. littorea
Effects of environmental stress on the condition of <i>Littorina littorea</i> along the Scheldt Estuary (the Netherlands)
The condition of the periwinkle Littorina littorea, expressed in terms of its shell morphology, reproductive impairment (i.e. female sterility/intersex, male penis shedding), trematode infestation load, lipid reserves and dry/wet weight ratio, was determined in function of environmental stress along the polluted Western and relatively clean Eastern Scheldt estuary (The Netherlands). The upstream increasing pollution and decreasing salinity levels along the Western Scheldt estuary (Fig. 1) are reflected in the dry/wet weight ratio and lipid content of the periwinkles. Compared to the Eastern Scheldt, female intersex (i.e. indicator of TBT pollution) and sterility occurred more frequently in the Western Scheldt estuary, while male penis shedding was even restricted to the latter estuary. The highest population intersex and sterility incidence was found near the harbour of Vlissingen and reflects potential nautical activities. The number of trematode infested periwinkles did not differ between both estuaries, although local sampling site differences were detected within each estuary, reflecting the complex interactions that exist among parasites, hosts and the local environment. Finally, both estuaries were maximally discriminated from each other based on the shell weight of the periwinkles using a canonical discriminant analysis. Periwinkles with the heaviest shells were found in the Western Scheldt estuary and may reflect growth rate or structural population differences caused by the less favourable living conditions in the Western Scheldt estuary
Efficiency at maximum power: An analytically solvable model for stochastic heat engines
We study a class of cyclic Brownian heat engines in the framework of
finite-time thermodynamics. For infinitely long cycle times, the engine works
at the Carnot efficiency limit producing, however, zero power. For the
efficiency at maximum power, we find a universal expression, different from the
endoreversible Curzon-Ahlborn efficiency. Our results are illustrated with a
simple one-dimensional engine working in and with a time-dependent harmonic
potential.Comment: 6 pages, 3 figure
Diffusion of interacting particles in discrete geometries: equilibrium and dynamical properties
We expand on a recent study of a lattice model of interacting particles
[Phys. Rev. Lett. 111, 110601 (2013)]. The adsorption isotherm and equilibrium
fluctuations in particle number are discussed as a function of the interaction.
Their behavior is similar to that of interacting particles in porous materials.
Different expressions for the particle jump rates are derived from transition
state theory. Which expression should be used depends on the strength of the
inter-particle interactions. Analytical expressions for the self- and transport
diffusion are derived when correlations, caused by memory effects in the
environment, are neglected. The diffusive behavior is studied numerically with
kinetic Monte Carlo (kMC) simulations, which reproduces the diffusion including
correlations. The effect of correlations is studied by comparing the analytical
expressions with the kMC simulations. It is found that the Maxwell-Stefan
diffusion can exceed the self-diffusion. To our knowledge, this is the first
time this is observed. The diffusive behavior in one-dimensional and higher
dimensional systems is qualitatively the same, with the effect of correlations
decreasing for increasing dimension. The length dependence of both the self-
and transport diffusion is studied for one-dimensional systems. For long
lengths the self-diffusion shows a one over length dependence. Finally, we
discuss when agreement with experiments and simulations can be expected. The
assumption that particles in different cavities do not interact is expected to
hold quantitatively at low and medium particle concentrations, if the particles
are not strongly interacting.Comment: (18 pages, 16 figures, published version
Parameter estimation for strong phase transitions in supranuclear matter using gravitational-wave astronomy
At supranuclear densities, explored in the core of neutron stars, a strong
phase transition from hadronic matter to more exotic forms of matter might be
present. To test this hypothesis, binary neutron-star mergers offer a unique
possibility to probe matter at densities that we can not create in any existing
terrestrial experiment. In this work, we show that, if present, strong phase
transitions can have a measurable imprint on the binary neutron-star
coalescence and the emitted gravitational-wave signal. We construct a new
parameterization of the supranuclear equation of state that allows us to test
for the existence of a strong phase transition and extract its characteristic
properties purely from the gravitational-wave signal of the inspiraling neutron
stars. We test our approach using a Bayesian inference study simulating 600
signals with three different equations of state and find that for current
gravitational-wave detector networks already twelve events might be sufficient
to verify the presence of a strong phase transition. Finally, we use our
methodology to analyze GW170817 and GW190425, but do not find any indication
that a strong phase transition is present at densities probed during the
inspiral.Comment: 17 pages, 11 figure
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