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Extreme H isotopic anomalies in chondritic organic matter
Extract from introduction: We have conducted ionprobe (IMS6f and NanoSIMS) imaging studies of various samples for H, D, C, 14N and 15N. These will ultimately be correlated with micro-analytic techniques such as FIB/TEM or STXM/XANES. We analyzed matrix fragments from Bells (CM2), Al Rais (CR2) and Tagish Lake (unique) [2], high purity insoluble organic matter (IOM) [3] extracted from EET92042 (“EET”, CR2), Bells, Murchison (CM2), Allende (CV3), Krymka (LL3.1) and, for comparison, 3 IDPs
Nonmonotonic Evolution of the Blocking Temperature in Dispersions of Superparamagnetic Nanoparticles
We use a Monte Carlo approach to simulate the influence of the dipolar
interaction on assemblies of monodisperse superparamagnetic
nanoparticles. We have identified a critical
concentration c*, that marks the transition between two different regimes in
the evolution of the blocking temperature () with interparticle
interactions. At low concentrations (c < c*) magnetic particles behave as an
ideal non-interacting system with a constant . At concentrations c > c*
the dipolar energy enhances the anisotropic energy barrier and
increases with increasing c, so that a larger temperature is required to reach
the superparamagnetic state. The fitting of our results with classical particle
models and experiments supports the existence of two differentiated regimes.
Our data could help to understand apparently contradictory results from the
literature.Comment: 13 pages, 7 figure
Experimental Verification of Surface Vehicle Dynamics
Experimental verification of surface vehicle dynamic
Carbon-rich presolar grains from massive stars : subsolar ¹²C/¹³C and ¹⁴N/¹⁵N ratios and the mystery of ¹⁵N
Carbon-rich grains with isotopic anomalies compared to the Sun are found in primitive meteorites. They were made by stars, and carry the original stellar nucleosynthesis signature. Silicon carbide grains of Type X and C and low-density (LD) graphites condensed in the ejecta of core-collapse supernovae. We present a new set of models for the explosive He shell and compare them with the grains showing ¹²C/¹³C and ¹⁴N/¹⁵N ratios lower than solar. In the stellar progenitor H was ingested into the He shell and not fully destroyed before the explosion. Different explosion energies and H concentrations are considered. If the supernova shock hits the He-shell region with some H still present, the models can reproduce the C and N isotopic signatures in C-rich grains. Hot-CNO cycle isotopic signatures are obtained, including a large production of ¹³C and ¹⁵N. The short-lived radionuclides ²²Na and ²⁶Al are increased by orders of magnitude. The production of radiogenic ²²Ne from the decay of ²²Na in the He shell might solve the puzzle of the Ne-E(L) component in LD graphite grains. This scenario is attractive for the SiC grains of type AB with ¹⁴N/¹⁵N ratios lower than solar, and provides an alternative solution for SiC grains originally classified as nova grains. Finally, this process may contribute to the production of ¹⁴N and ¹⁵N in the Galaxy, helping to produce the ¹⁴N/¹⁵N ratio in the solar system
Solar oxygen abundance using SST/CRISP center-to-limb observations of the O I 7772 \r{A} line
Solar oxygen abundance measurements based on the O I near-infrared triplet
have been a much-debated subject for several decades since non-local
thermodynamic equilibrium (NLTE) calculations with 3D radiation-hydrodynamics
model atmospheres introduced a large change to the 1D LTE modelling. In this
work, we aim to test solar line formation across the solar disk using new
observations obtained with the SST/CRISP instrument. The observed dataset is
based on a spectroscopic mosaic stretching from disk center to the solar limb.
By comparing the state-of-the-art 3D NLTE models with the data, we find that
the 3D NLTE models provide an excellent description of line formation across
the disk. We obtain an abundance value of
dex, with a very small angular dispersion across the disk. We conclude that
spectroscopic mosaics are excellent probes for geometric and physical
properties of hydrodynamics models and non-LTE line formation.Comment: Accepted in A&
Leveraging multilingual descriptions for link prediction: Initial experiments
In most Knowledge Graphs (KGs), textual descriptions ofentities are provided in multiple natural languages. Additional informa-tion that is not explicitly represented in the structured part of the KGmight be available in these textual descriptions. Link prediction modelswhich make use of entity descriptions usually consider only one language.However, descriptions given in multiple languages may provide comple-mentary information which should be taken into consideration for thetasks such as link prediction. In this poster paper, the benefits of mul-tilingual embeddings for incorporating multilingual entity descriptionsinto the task of link prediction in KGs are investigate
Heavy metal recovery from the fine fraction of solid waste incineration bottom ash by wet density separation
This work is aimed at exploring the recovery of heavy metals from the fine fraction of solid waste incineration bottom ash. For this study, wet-discharged bottom ash fine-fraction samples from full-scale treatment plants in Germany and Sweden were analyzed. The potential for the recovery of heavy metal compounds was investigated through wet density-separation with a shaking table. The feed materials were processed without any pre-treatment and the optimum processing conditions were determined by means of design of experiments. Tilt angle and stroke frequency were identified as the most relevant parameters, and the optimum settings were − 7.5° and 266 rpm, respectively. The obtained balanced copper enrichments (and yields) were 4.4 (41%), 6.2 (28%) and 2.4 (23%). A maximum copper enrichment of 14.5 with 2% yield was achieved, providing a concentrate containing 35.9 wt.% relevant heavy metal elements. This included 26.3 wt.% iron, 4.3 wt.% zinc and 3.8 wt.% copper. In conclusion, density separation with shaking tables can recover heavy metals from bottom ash fine fractions. Medium levels of heavy metal enrichment (e.g., for Cu 2.7–4.4) and yield (Cu: 26–41%) can be reached simultaneously. However, the separation performance also depends on the individual bottom ash sample
Profile and width of rough interfaces
In the context of Landau theory and its field theoretical refinements,
interfaces between coexisting phases are described by intrinsic profiles. These
intrinsic interface profiles, however, are neither directly accessible by
experiment nor by computer simulation as they are broadened by long-wavelength
capillary waves. In this paper we study the separation of the small scale
intrinsic structure from the large scale capillary wave fluctuations in the
Monte Carlo simulated three-dimensional Ising model. To this purpose, a
blocking procedure is applied, using the block size as a variable cutoff, and a
translationally invariant method to determine the interface position of
strongly fluctuating profiles on small length scales is introduced. While the
capillary wave picture is confirmed on large length scales and its limit of
validity is estimated, an intrinsic regime is, contrary to expectations, not
observed.Comment: 18 pages, 4 Postscript figures, LaTeX2e, formulation of sec.3.2
improved, 1 reference adde
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