Insight
is our reward
Search

Publications in Fluids & Plasmas by NOMIS researchers

Leaf metabolic traits reveal hidden dimensions of plant form and function

NOMIS Researcher(s)

Published in

August 30, 2023

The metabolome is the biochemical basis of plant form and function, but we know little about its macroecological variation across the plant kingdom. Here, we used the plant functional trait concept to interpret leaf metabolome variation among 457 tropical and 339 temperate plant species. Distilling metabolite chemistry into five metabolic functional traits reveals that plants vary on two major axes of leaf metabolic specialization—a leaf chemical defense spectrum and an expression of leaf longevity. Axes are similar for tropical and temperate species, with many trait combinations being viable. However, metabolic traits vary orthogonally to life-history strategies described by widely used functional traits. The metabolome thus expands the functional trait concept by providing additional axes of metabolic specialization for examining plant form and function. Copyright © 2023 The Authors,

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1126/sciadv.adi4029

X-ray Thomson scattering spectra from density functional theory molecular dynamics simulations based on a modified Chihara formula

NOMIS Researcher(s)

Published in

June 14, 2023

We study ab initio approaches for calculating x-ray Thomson scattering spectra from density functional theory molecular dynamics simulations based on a modified Chihara formula that expresses the inelastic contribution in terms of the dielectric function. We study the electronic dynamic structure factor computed from the Mermin dielectric function using an ab initio electron-ion collision frequency in comparison to computations using a linear-response time-dependent density functional theory (LR-TDDFT) framework for hydrogen and beryllium and investigate the dispersion of free-free and bound-free contributions to the scattering signal. A separate treatment of these contributions, where only the free-free part follows the Mermin dispersion, shows good agreement with LR-TDDFT results for ambient-density beryllium, but breaks down for highly compressed matter where the bound states become pressure ionized. LR-TDDFT is used to reanalyze x-ray Thomson scattering experiments on beryllium demonstrating strong deviations from the plasma conditions inferred with traditional analytic models at small scattering angles. © 2023 American Physical Society.

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1103/PhysRevE.107.065207

Melting curve of superionic ammonia at planetary interior conditions

NOMIS Researcher(s)

Published in

May 29, 2023

Under high pressures and temperatures, molecular systems with substantial polarization charges, such as ammonia and water, are predicted to form superionic phases and dense fluid states with dissociating molecules and high electrical conductivity. This behaviour potentially plays a role in explaining the origin of the multipolar magnetic fields of Uranus and Neptune, whose mantles are thought to result from a mixture of H2O, NH3 and CH4 ices. Determining the stability domain, melting curve and electrical conductivity of these superionic phases is therefore crucial for modelling planetary interiors and dynamos. Here we report the melting curve of superionic ammonia up to 300 GPa from laser-driven shock compression of pre-compressed samples and atomistic calculations. We show that ammonia melts at lower temperatures than water above 100 GPa and that fluid ammonia’s electrical conductivity exceeds that of water at conditions predicted by hot, super-adiabatic models for Uranus and Neptune, and enhances the conductivity in their fluid water-rich dynamo layers. © 2023, The Author(s), under exclusive licence to Springer Nature Limited.

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1038/s41567-023-02074-8

Curvature induces active velocity waves in rotating spherical tissues

NOMIS Researcher(s)

Published in

March 24, 2023

The multicellular organization of diverse systems, including embryos, intestines, and tumors relies on coordinated cell migration in curved environments. In these settings, cells establish supracellular patterns of motion, including collective rotation and invasion. While such collective modes have been studied extensively in flat systems, the consequences of geometrical and topological constraints on collective migration in curved systems are largely unknown. Here, we discover a collective mode of cell migration in rotating spherical tissues manifesting as a propagating single-wavelength velocity wave. This wave is accompanied by an apparently incompressible supracellular flow pattern featuring topological defects as dictated by the spherical topology. Using a minimal active particle model, we reveal that this collective mode arises from the effect of curvature on the active flocking behavior of a cell layer confined to a spherical surface. Our results thus identify curvature-induced velocity waves as a mode of collective cell migration, impacting the dynamical organization of 3D curved tissues. © 2023, The Author(s).

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1038/s41467-023-37054-2

Thermodynamics of diamond formation from hydrocarbon mixtures in planets

NOMIS Researcher(s)

Published in

February 27, 2023

Hydrocarbon mixtures are extremely abundant in the Universe, and diamond formation from them can play a crucial role in shaping the interior structure and evolution of planets. With first-principles accuracy, we first estimate the melting line of diamond, and then reveal the nature of chemical bonding in hydrocarbons at extreme conditions. We finally establish the pressure-temperature phase boundary where it is thermodynamically possible for diamond to form from hydrocarbon mixtures with different atomic fractions of carbon. Notably, here we show a depletion zone at pressures above 200 GPa and temperatures below 3000 K-3500 K where diamond formation is thermodynamically favorable regardless of the carbon atomic fraction, due to a phase separation mechanism. The cooler condition of the interior of Neptune compared to Uranus means that the former is much more likely to contain the depletion zone. Our findings can help explain the dichotomy of the two ice giants manifested by the low luminosity of Uranus, and lead to a better understanding of (exo-)planetary formation and evolution. © 2023, The Author(s).

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1038/s41467-023-36841-1

Effects of boundary layer thickness on the estimation of equivalent sandgrain roughness in zero-pressure-gradient boundary layers

NOMIS Researcher(s)

Published in

August 1, 2022

Experiments were conducted in zero-pressure-gradient boundary layers over a rough surface. Profiles of mean velocity and turbulence quantities were acquired using laser Doppler velocimetry at twelve streamwise locations for each of three different freestream velocities. Momentum thickness Reynolds numbers ranged from 1550 to 13,650. The roughness was stochastic with positive skewness, and the ratio of the boundary layer thickness, δ, to the root-mean-square roughness height varied from 55 to 141. The equivalent sandgrain roughness height, ks, was approximately 4 times the rms roughness height. In the outer region of the boundary layer, the mean velocity and turbulence results were found to be invariant with Reynolds number and δ, when scaled using δ and the friction velocity. The outer region quantities exhibited similarity with equivalent smooth-wall boundary layer quantities, in agreement with results from the literature. The equivalent sandgrain roughness was computed from the mean velocity results using a standard correlation, and was found to vary noticeably and inversely with δ when δ/ks was less than about 40. The possible existence of a modified correlation to account for the δ/ks dependence was discussed. Such a correlation might prove useful for extracting ks values from low δ/ks data and for predicting the effect of roughness with a known ks on boundary layers with varying δ/ks. Graphical abstract: [Figure not available: see fulltext.]

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1007/s00348-022-03479-6

Sequence-dependent surface condensation of a pioneer transcription factor on DNA

NOMIS Researcher(s)

Published in

March 1, 2022

Biomolecular condensates are dense assemblies of proteins that form distinct biochemical compartments without being surrounded by a membrane. Some, such as P granules and stress granules, behave as droplets and contain many millions of molecules. Others, such as transcriptional condensates that form on the surface of DNA, are small and contain thousands of molecules. The physics behind the formation of small condensates on DNA surfaces is still under discussion. Here we investigate the nature of transcription factor condensates using the pioneer transcription factor Krüppel-like factor 4 (Klf4). We show that Klf4 can phase separate on its own at high concentrations, but at low concentrations, Klf4 only forms condensates on DNA. Using optical tweezers, we demonstrate that these Klf4 condensates form on DNA as a type of surface condensation. This surface condensation involves a switch-like transition from a thin adsorbed layer to a thick condensed layer, which shows hallmarks of a prewetting transition. The localization of condensates on DNA correlates with sequence, suggesting that the condensate formation of Klf4 on DNA is a sequence-dependent form of surface condensation. Prewetting together with sequence specificity can explain the size and position control of surface condensates. We speculate that a prewetting transition of pioneer transcription factors on DNA underlies the formation and positioning of transcriptional condensates and provides robustness to transcriptional regulation.

Research field(s)
Natural Sciences, Physics & Astronomy, Fluids & Plasmas

DOI
10.1038/s41567-021-01462-2

  • NOMIS Foundation 2024
  • 2024 NOMIS Foundation