333 research outputs found
Online Search Tool for Graphical Patterns in Electronic Band Structures
We present an online graphical pattern search tool for electronic band
structure data contained within the Organic Materials Database (OMDB) available
at https://omdb.diracmaterials.org/search/pattern. The tool is capable of
finding user-specified graphical patterns in the collection of thousands of
band structures from high-throughput ab initio calculations in the online
regime. Using this tool, it only takes a few seconds to find an arbitrary
graphical pattern within the ten electronic bands near the Fermi level for
26,739 organic crystals. The tool can be used to find realizations of
functional materials characterized by a specific pattern in their electronic
structure, for example, Dirac materials, characterized by a linear crossing of
bands; topological insulators, characterized by a "Mexican hat" pattern or an
effectively free electron gas, characterized by a parabolic dispersion. The
source code of the developed tool is freely available at
https://github.com/OrganicMaterialsDatabase/EBS-search and can be transferred
to any other electronic band structure database. The approach allows for an
automatic online analysis of a large collection of band structures where the
amount of data makes its manual inspection impracticable.Comment: 8 pages, 8 figure
Neo-Atlantis: Dutch Responses to Five Meter Sea Level Rise
What would happen to the Netherlands if, in 2030, the sea level starts to rise and eventually, after 100 years, a sea level of five meters above current level would be reached? Two socio-economic scenarios are developed from a literature review and by interviews with researchers and practicionersin the domains of social sciences, economics, civil engineering, and land use planning. One scenario describes what would happen in a future characterised by a trend towards further globalisation, marketisation and high economic growth, while the other scenario happens in a future under opposite trends. Under both scenarios, the Southwest and Northwest of the Netherlands – already now below seal level - would be abandoned because of sea level rise. Although most experts believe that geomorphology and current engineering skills allow to largely maintain the territorial integrity of the Netherlands, there are some reasons to assume that this is not likely to happen. Social processes that precede important political decisions – such as the growth of the belief in the reality of SLR and the framing of such decision in a proper political context (policy window) – evolve slowly. Although a flood disaster would speed up decision-making, the general expectation is that decisions would come too late in view of the rate of SLR and the possible pace of construction of works.Extreme sea level rise, The Netherlands, flood defences
The Dynamics of Asymmetric Stratified Shear Instabilities
Most idealized studies of stratified shear instabilities assume that the
shear interface and the buoyancy interface are coincident. We discuss the role
of asymmetry on the evolution of shear instabilities. Using linear stability
theory and direct numerical simulations, we show that asymmetric shear
instabilities exhibit features of both Holmboe and Kelvin-Helmholtz (KH)
instabilities, and develop a framework to quantify if the instabilities are
more Holmboe-like or more KH-like. Further, the asymmetric instabilities
produce asymmetric mixing that exhibits features of both overturning and
scouring flows and that tends to realign the shear and buoyancy interfaces. In
all but the symmetric KH simulations, we observe a collapse in the distribution
of gradient Richardson number (), suggesting that asymmetry reduces the
parameter dependence of KH-driven mixing events. The observed dependence of the
turbulent dynamics on small-scale details of the shear and stratification has
important implications for the interpretation of oceanographic data.Comment: 9 Figures, 21 page
Stimulation of ribosomal frameshifting by antisense LNA
Programmed ribosomal frameshifting is a translational recoding mechanism commonly used by RNA viruses to express two or more proteins from a single mRNA at a fixed ratio. An essential element in this process is the presence of an RNA secondary structure, such as a pseudoknot or a hairpin, located downstream of the slippery sequence. Here, we have tested the efficiency of RNA oligonucleotides annealing downstream of the slippery sequence to induce frameshifting in vitro. Maximal frameshifting was observed with oligonucleotides of 12–18 nt. Antisense oligonucleotides bearing locked nucleid acid (LNA) modifications also proved to be efficient frameshift-stimulators in contrast to DNA oligonucleotides. The number, sequence and location of LNA bases in an otherwise DNA oligonucleotide have to be carefully manipulated to obtain optimal levels of frameshifting. Our data favor a model in which RNA stability at the entrance of the ribosomal tunnel is the major determinant of stimulating slippage rather than a specific three-dimensional structure of the stimulating RNA element
The effect of a density gradient in groundwater on ATES system efficiency and subsurface space use
A heat pump combined with Aquifer Thermal Energy Storage (ATES) has high
potential in efficiently and sustainably providing thermal energy for space
heating and cooling. This makes the subsurface, including its groundwater, of
crucial importance for primary energy savings. ATES systems are often placed
in aquifers in which salinity increases with depth. This is the case in
coastal areas where also the demand for ATES application is high due to high
degrees of urbanization in those areas. The seasonally alternating extraction
and re-injection between ATES wells disturbs the preexisting ambient salinity
gradient causing horizontal density gradients, which trigger buoyancy flow,
which in turn affects the recovery efficiency of the stored thermal energy.This section uses analytical and numerical methods to understand and explain
the impact of buoyancy flow on the efficiency of ATES in such situations, and
to quantify the magnitude of this impact relative to other thermal energy
losses. The results of this research show that losses due to buoyancy flow
may become considerable at (a relatively large) ambient density gradients of
over 0.5 kg m−3 m−1 in combination with a vertical hydraulic
conductivity of more than 5 m day−1. Monowell systems suffer more from
buoyancy losses than do doublet systems under similar conditions.</p
Investigating the impact of exopolysaccharides on yogurt network mechanics and syneresis through quantitative microstructural analysis
Exopolysaccharides produced by lactic acid bacteria are widely used to improve the sensory properties of yogurt. The relation between the physical properties of the microbial exopolysaccharides and the structural and rheological properties of the yogurt are incompletely understood to date. To address this knowledge gap, we studied how two distinct exopolysaccharides influence the microstructure, rheological properties, and syneresis of yogurt. The effect of a negatively charged, capsular exopolysaccharide produced by Streptococcus thermophilus and a neutral, non-capsular exopolysaccharide produced by Lactococcus lactis were investigated. Using quantitative microstructural analysis, we examined yogurt samples prepared with either the capsular or the non-capsular exopolysaccharide, and with mixtures of the two. Confocal laser scanning microscopy and stimulated emission depletion microscopy were employed to visualize the microstructures, revealing differences in pore size distribution, protein domain size, and casein interconnectivity that were not apparent through visual inspection alone. Additionally, variations in rheological properties were observed among the different yogurt types. In the yogurt fermented with both bacterial strains, we observed a combined impact of the two exopolysaccharide types on relevant microstructural and rheological properties. The negatively charged capsular exopolysaccharide enhanced casein interconnectivity and gel stiffness, while the neutral non-capsular exopolysaccharide led to thicker protein domains, an abundance of small pores, and a lower loss tangent. These factors collectively hindered syneresis, resulting in improved structural integrity. Our study not only provides valuable insights into the influence of different exopolysaccharides on yogurt properties, but also presents the first demonstration and quantification of the effect of multiple types of exopolysaccharides on casein interconnectivity. These findings offer guidance for the production of yogurts with customized microstructure, rheological properties, and resistance to syneresis.<br/
The subgenomic promoter of brome mosaic virus folds into a stem-loop structure capped by a pseudo-triloop that is structurally similar to the triloop of the genomic promoter
Supramolecular & Biomaterials Chemistr
Probing the plateau-insulator quantum phase transition in the quantum Hall regime
We report quantum Hall experiments on the plateau-insulator transition in a
low mobility In_{.53} Ga_{.47} As/InP heterostructure. The data for the
longitudinal resistance \rho_{xx} follow an exponential law and we extract a
critical exponent \kappa= .55 \pm .05 which is slightly different from the
established value \kappa = .42 \pm .04 for the plateau transitions. Upon
correction for inhomogeneity effects, which cause the critical conductance
\sigma_{xx}^* to depend marginally on temperature, our data indicate that the
plateau-plateau and plateau- insulator transitions are in the same universality
class.Comment: 4 pages, 4 figures (.eps
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