38 research outputs found
Developments and Further Applications of Ephemeral Data Derived Potentials
Machine-learned interatomic potentials are fast becoming an indispensable
tool in computational materials science. One approach is the ephemeral
data-derived potential (EDDP), which was designed to accelerate atomistic
structure prediction. The EDDP is simple and cost-efficient. It relies on
training data generated in small unit cells and is fit using a lightweight
neural network, leading to smooth interactions which exhibit the robust
transferability essential for structure prediction. Here, we present a variety
of applications of EDDPs, enabled by recent developments of the open-source
EDDP software. New features include interfaces to phonon and molecular dynamics
codes, as well as deployment of the ensemble deviation for estimating the
confidence in EDDP predictions. Through case studies ranging from elemental
carbon and lead to the binary scandium hydride and the ternary zinc cyanide, we
demonstrate that EDDPs can be trained to cover wide ranges of pressures and
stoichiometries, and used to evaluate phonons, phase diagrams, superionicity,
and thermal expansion. These developments complement continued success in
accelerated structure prediction.Comment: 22 pages, 15 figure
Theory of Banana Liquid Crystal Phases and Phase Transitions
We study phases and phase transitions that can take place in the newly
discovered banana (bow-shaped or bent-core) liquid crystal molecules. We show
that to completely characterize phases exhibited by such bent-core molecules a
third-rank tensor order parameter is necessary in addition to the
vector and the nematic (second-rank) tensor order parameters. We present an
exhaustive list of possible liquid phases, characterizing them by their
space-symmetry group and order parameters, and catalog the universality classes
of the corresponding phase transitions that we expect to take place in such
bent-core molecular liquid crystals. In addition to the conventional
liquid-crystal phases such as the nematic phase, we predict the existence of
novel liquid phases, including the spontaneously chiral nematic
and chiral polar phases, the orientationally-ordered but
optically isotropic tetrahedratic phase, and a novel nematic phase
with symmetry that is neither uniaxial nor biaxial. Interestingly, the
Isotropic-Tetrahedratic transition is {\em continuous} in mean-field theory,
but is likely driven first-order by thermal fluctuations. We conclude with a
discussion of smectic analogs of these phases and their experimental
signatures.Comment: 28 pgs. RevTex, 32 eps figures, submitted to Phys. Rev.
Inducing Ni Sensitivity in the Ni Hyperaccumulator Plant Alyssum inflatum Nyárády (Brassicaceae) by Transforming with CAX1, a Vacuolar Membrane Calcium Transporter
The importance of calcium in nickel tolerance was studied in the nickel hyperaccumulator plant Alyssum inflatum by gene transformation of CAX1, a vacuolar membrane transporter that reduces cytosolic calcium. CAX1 from Arabidopsis thaliana with a CaMV35S promoter accompanying a kanamycin resistance gene was transferred into A. inflatum using Agrobacterium tumefaciens. Transformed calli were subcultured three times on kanamycin-rich media and transformation was confirmed by PCR using a specific primer for CAX1. At least 10 callus lines were used as a pool of transformed material. Both transformed and untransformed calli were treated with varying concentrations of either calcium (1–15 mM) or nickel (0– 500 lM) to compare their responses to those ions. Increased external calcium generally led to increased callus biomass, however, the increase was greater for untransformed callus. Further, increased external calcium led to increased callus calcium concentrations. Transformed callus was less nickel tolerant than untransformed callus: under increasing nickel concentrations callus relative growth rate was significantly less for transformed callus. Transformed callus also contained significantly less nickel than untransformed callus when exposed to the highest external nickel concentration (200 lM). We suggest that transformation with CAX1 decreased cytosolic calcium and resulted in decreased nickel tolerance. This in turn suggests that, at low cytosolic calcium concentrations, other nickel tolerance mechanisms (e.g., complexation and vacuolar sequestration) are insufficient for nickel tolerance. We propose that high cytosolic calcium is an important mechanism that results in nickel tolerance by nickel hyperaccumulator plants
Bitumen high temperature properties characterised by multiple stress creep recovery test (MSCR)
W artykule opisano metodę pomiaru właściwości wysokotemperaturowych asfaltów stosowaną do oceny rodzaju funkcjonalnego (PG) lepiszczy wg Superpave. Przedstawiono wyniki badań asfaltu drogowego i asfaltów modyfikowanych poddanych badaniu cyklicznego pełzania z odprężeniem (MSCR). Przeanalizowano wyniki badań, wskazując możliwości zastosowania oceny sprężystości oraz podatności lepiszcza do określania obecności modyfikatora typu elastomerowego w asfaltach modyfikowanych polimerami.Method for characterised high temperature properties of bituminous binder apply for Superpave PG grade are described. Bituminous binder and polymer modified bitumen were tested by multiple stress creep recovery procedure (MSCR). Results of recovery and non-recoverable creep compliance were analysed in aspect to check sufficient modifier content
Efficiency Frontiers in Treating Lifestyle Diseases
Research background: Following a rational health policy by the state is tantamount to having knowledge of society’s health status and health affecting factors. It has become particularly important to focus on the 21st century diseases resulting in premature deaths. That objective dominated the 2016 Act on Public Health and the 2016–2020 National Health Programme connected with it