1,695 research outputs found
Spontaneous polarisation of the neutral interface for valence asymmetric coulombic systems
In this paper, we discuss the phenomenon of a spontaneous polarisation of a
neutral hard planar interface for valence asymmetric coulombic systems. Within
a field theoretical description, we account for the existence of non trivial
charge density and electric potential profiles. The analysis of the phenomenon
shows that the effect is related to combinatorics in relation with the
existence of the two independent species cations and anions. This simple and
basic feature is related to the quantum mechanical properties of the system.
The theoretical results are compared with numerical simulations data and are
shown to be in very good agreement, which a fortiori justifies our physical
interpretation.Comment: 12 pages, 11 figure
The effect of short-range interaction and correlations on the charge and electric field distribution in a model solid electrolyte
A simple lattice model of a solid electrolyte presented as a xy-slab geometry
system of mobile cations on a background of energetic landscape of the host
system and a compensating field of uniformly distributed anions is studied. The
system is confined in the z-direction between two oppositely charged walls,
which are in parallel to xy-plane. Besides the long-range Coulomb interactions
appearing in the system, the short-range attractive potential between cations
is considered in our study. We propose the mean field description of this model
and extend it by taking into account correlation effects at short distances.
Using the free energy minimization at each of z-coordinates, the corresponding
set of non-linear equations for the chemical potential is derived. The set of
equations was solved numerically with respect to the charge density
distribution in order to calculate the cations distribution profile and the
electrostatic potential in the system along z-direction under different
conditions. An asymmetry of charge distribution profile with respect to the
midplane of the system is observed. The effects of the short-range interactions
and pair correlations on the charge and electric field distributions are
demonstrated
Exact diagonalization of the Bohr Hamiltonian for rotational nuclei: Dynamical gamma softness and triaxiality
Detailed quantitative predictions are obtained for phonon and multiphonon
excitations in well-deformed rotor nuclei within the geometric framework, by
exact numerical diagonalization of the Bohr Hamiltonian in an SO(5) basis.
Dynamical gamma deformation is found to significantly influence the predictions
through its coupling to the rotational motion. Basic signatures for the onset
of rigid triaxial deformation are also obtained.Comment: 17 pages, 10 figures; to be published Phys. Rev.
Consequences of wall stiffness for a beta-soft potential
Modifications of the infinite square well E(5) and X(5) descriptions of
transitional nuclear structure are considered. The eigenproblem for a potential
with linear sloped walls is solved. The consequences of the introduction of
sloped walls and of a quadratic transition operator are investigated.Comment: RevTeX 4, 8 pages, as published in Phys. Rev.
Shedding Light on Diatom Photonics by means of Digital Holography
Diatoms are among the dominant phytoplankters in the worl's ocean, and their
external silica investments, resembling artificial photonics crystal, are
expected to play an active role in light manipulation. Digital holography
allowed studying the interaction with light of Coscinodiscus wailesii cell wall
reconstructing the light confinement inside the cell cytoplasm, condition that
is hardly accessible via standard microscopy. The full characterization of the
propagated beam, in terms of quantitative phase and intensity, removed a
long-standing ambiguity about the origin of the light. The data were discussed
in the light of living cell behavior in response to their environment
A formally exact field theory for classical systems at equilibrium
We propose a formally exact statistical field theory for describing classical
fluids with ingredients similar to those introduced in quantum field theory. We
consider the following essential and related problems : i) how to find the
correct field functional (Hamiltonian) which determines the partition function,
ii) how to introduce in a field theory the equivalent of the indiscernibility
of particles, iii) how to test the validity of this approach. We can use a
simple Hamiltonian in which a local functional transposes, in terms of fields,
the equivalent of the indiscernibility of particles. The diagrammatic expansion
and the renormalization of this term is presented. This corresponds to a non
standard problem in Feynman expansion and requires a careful investigation.
Then a non-local term associated with an interaction pair potential is
introduced in the Hamiltonian. It has been shown that there exists a mapping
between this approach and the standard statistical mechanics given in terms of
Mayer function expansion. We show on three properties (the chemical potential,
the so-called contact theorem and the interfacial properties) that in the field
theory the correlations are shifted on non usual quantities. Some perspectives
of the theory are given.Comment: 20 pages, 8 figure
Honey Bees (Apis mellifera, L.) as Active Samplers of Airborne Particulate Matter
© 2015 Negri et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. [CC by 4.0] The attached file is the published version of the article
Small fragments sodium sulfated hyaluronate, more than hyaluronic acid, reduces LPS-induced cytokine/chemokine levels in HaCaT cells
Hyaluronic acid (HA) is a linear non-sulphated glycosaminoglycan, used in dermatology as a
biomaterial for bioengineering purposes, temporary dermal filler, stimulation of wound healing
as well as drug vehicle in topical formulations. In addition to the well-characterized
structural properties, extensive research on HA has revealed a range of vastly immunemodulatory
effects, dependent on its size. In this in vitro study we investigated the ability of
HA-S3, a small fragment HA (MW, molecular weight: 68 kDa) with degree of sulphatation
of 3 and of HA fraction (MW:210 kDa) to reduce the bacterial induced inflammatory response
in spontaneous immortalized keratinocytes. To this purpose, HaCaT cells were treated for
24 hours with 25 µg/ml of E. Coli derived bacterial lipopolysaccharide (LPS) in absence or
presence of small fragment HA-S3 or HA. Cell viability was thereafter assessed using trypan
blue stain and interleukin (IL)-8, IL-1β and tumor necrosis factor alpha (TNF-α) concentrations
were determined in cell supernatants by single enzyme-linked immunoadsorbent assay
(ELISA). Our results showed that cell viability was not affected either by HA-S3 or HA which
in turn were able to reduce LPS-induced mortality. HA and especially HA-S3 were able to
significantly reduce LPS-induced pro-inflammatory cytokines. Our observation might suggest
new perspectives in the development of HA-S3 containing topical products able to modulate
cutaneous inflammatory response
- …