219 research outputs found
Nucleation and phase selection in undercooled melts: Magnetic alloys of industrial relevance (MAGNEPHAS)
Studies of phase selection and microstructure evolution in high-performance magnetic materials are an urgent need for optimization of production routes. Containerless solidification experiments by electromagnetic levitation and drop tube solidification were conducted in undercooled melts of Fe-Co, Fe-Ni soft magnetic, and Nd-Fe-B hard magnetic alloys. Melt undercooling under microgravity was achieved in the TEMPUS facility during parabolic flight campaigns. For Fe-Co and Fe-Ni alloys significant effects of microgravity on metastable phase formation were discovered. Microstructure modifications as well as metastable phase formation as function of undercooling and melt flow were elucidated in Nd-Fe-B. Modeling of solidification processes, fluid flow and heat transfer provide predictive tools for microstructure engineering from the melt. They were developed as a link between undercooling experiments under terrestrial and microgravity conditions and the production routes of magnetic materials
Magnetic behavior of single crystalline HoPdSi
The magnetic behavior of single-crystal HoPdSi, crystallizing in an
AlB-derived hexagonal structure, is investigated by magnetic susceptibility
() and electrical resistivity () measurements along two directions.
There is no dramatic anisotropy in the high temperature Curie-Weiss parameter
or in the and isothermal magnetization data, though there is a
noticeable anisotropy in the magnitude of between two perpendicular
orientations. The degree of anisotropy is overall less prominent than in the Gd
(which is an S-state ion!) and Tb analogues. A point of emphasis is that this
compound undergoes long range magnetic ordering below 8 K as in the case of
analogous Gd and Dy compounds. Considering this fact for these compounds with
well-localised f-orbital, the spin glass freezing noted for isomorphous U
compounds in the recent literature could be attributed to the role of the
f-ligand hybridization, rather than just Pd-Si disorder.Comment: Physical Review B, in pres
Entwicklung, Erprobung, Umsetzung und Evaluation von Strategien in den Bereichen Tiergesundheit, Haltung, Fütterung, Management in der ökologischen Ferkelerzeugung
Die ökologische Ferkelerzeugung weist hinsichtlich Tiergesundheit, Leistungsfähigkeit und Wirtschaftlichkeit große Defizite auf. Die Ursachen sind komplex und betreffen u.a. Fütterung, Haltung und Hygiene. Für diese Bereiche sollten durch Exakt- und Praxisversuche Lösungsansätze entwickelt werden. Teilprojekte umfassten folgende Themen: Der Einfluss unterschiedlicher Raufutter in der Fütterung tragender Sauen, die Wirkung einer Inulinzugabe sowie vom Extrudieren von Ackerbohnen in Sauen- und Ferkelfutter, die Bewertung alternativer Desinfektionsverfahren, ein Vergleich von Einzelhaltung versus kombinierte Einzel- und Gruppenhaltung säugender Sauen sowie die Optimierung des Ferkelliegebereichs in der Ferkelaufzucht.
Zentrale Ergebnisse:
- Die verschiedenen Raufuttervarianten (Kleegrassilage, Heu, Maissilage, Topinamburknollen) hatten keine negativen Effekte auf Körperkonstitution und Reproduktionsleistungen der Sauen.
- Die Saugferkel der mit Inulin versorgten Sauen entwickelten sich gegenüber der Kontrollgruppe während der Säugezeit leistungsmäßig besser, während der Ferkelaufzucht gab es keine Leistungssteigerungen. Der Einsatz von getoasteten Ackerbohnen führte zu signifikant besseren Ferkelzunahmen gegenüber dem Einsatz von extrudierten Ackerbohnen.
- Keines der getesteten alternativen Desinfektionsverfahren (Heißwasserdampf, elektroaktiviertes Wasser, Abflammen) ist eine Alternative zur chemischen Desinfektion bezüglich Keimreduktion, Arbeitsaufwand und Kosten.
- Gruppensäugen führt bei Sauen zu erhöhter Aktivität sowie zu spezifischen Verhaltensanpassungen. Leistungseinbußen konnten weder für Sauen noch für Ferkel dokumentiert werden. „Gruppensäugen“ führt zu einem höheren Arbeitszeitbedarf und steigenden Baukosten.
- Der Liegebereich für Aufzuchtferkel ist in vielen Betrieben nicht optimal und durch z. T. einfache Maßnahmen (Abdichten des Liegenestes, Wärmedämmung des Bodens, Bodenheizung, Anbringen einer weiteren Wärmequelle) für die Tiere zu verbessern
Electronic disorder of P- and B-doped Si at the metal-insulator transition investigated by scanning tunnelling microscopy and electronic transport
The (111)-2 × 1 surface of in situ cleaved heavily P- or B-doped Si is investigated by scanning tunnelling microscopy and spectroscopy at room temperature and at low temperature. P atoms have been identified on different sites of the Si(111)-2 × 1 surface by their characteristic voltage-dependent contrast for positive as well as negative buckling of the π-bonded chains. The distributions of dopants per surface area and of nearest-neighbour distances are found to be in agreement with a random arrangement of dopants in Si up to doping levels well above the metal–insulator transition. In addition, P atoms have been identified by their depth-dependent contrast down to the third layer beneath the surface with a volume density in agreement with the bulk doping density. The random electronic disorder supports the view of an Anderson transition driven by disorder close to the critical concentration or critical uniaxial stress
FashionBrain Project: A Vision for Understanding Europe's Fashion Data Universe
A core business in the fashion industry is the understanding and
prediction of customer needs and trends. Search engines and social
networks are at the same time a fundamental bridge and a costly
middleman between the customer’s purchase intention and the
retailer. To better exploit Europe’s distinctive characteristics e.g.,
multiple languages, fashion and cultural differences, it is pivotal to
reduce retailers’ dependence to search engines. This goal can be
achieved by harnessing various data channels (manufacturers and
distribution networks, online shops, large retailers, social media,
market observers, call centers, press/magazines etc.) that retailers
can leverage in order to gain more insight about potential buyers,
and on the industry trends as a whole. This can enable the creation
of novel on-line shopping experiences, the detection of influencers,
and the prediction of upcoming fashion trends.
In this paper, we provide an overview of the main research
challenges and an analysis of the most promising technological
solutions that we are investigating in the FashionBrain project
Platinum Group Metal-Doped Tungsten Phosphates for Selective C-H Activation of Lower Alkanes
Platinum group metal (PGM)-based catalysts are known to be highly active in the total combustion of lower hydrocarbons. However, through an alternative catalyst design reported in this paper by isolating PGM-based active sites in a tungsten phosphate matrix, we present a class of catalysts for selective oxidation of n-butane, propane, and propylene that do not contain Mo or V as redox-active elements. Two different catalyst concepts have been pursued. Concept A: isolating Ru-based active sites in a tungsten phosphate matrix coming upon as ReO3-type structure. Concept B: dilution of PGM-based active sites through the synthesis of X-ray amorphous Ru tungsten phosphates supported on SiO2. Using a high-throughput screening approach, model catalysts over a wide compositional range were evaluated for C3 and C4 partial oxidation. Bulk crystalline and supported XRD amorphous phases with similar Ru/W/P compositions showed comparable performance. Hence, for these materials, composition is more crucial than the degree of crystallinity. Further studies for optimization on second-generation supported systems revealed even better results. High selectivity for n-butane oxidation to maleic anhydride and propane oxidation to an acrolein/acrylic acid has been achieved
Electronic structure and nesting-driven enhancement of the RKKY interaction at the magnetic ordering propagation vector in Gd2PdSi3 and Tb2PdSi3
We present first-time measurements of the Fermi surface and low-energy
electronic structure of intermetallic compounds Gd2PdSi3 and Tb2PdSi3 by means
of angle-resolved photoelectron spectroscopy (ARPES). Both materials possess a
flower-like Fermi surface consisting of an electron barrel at the G point
surrounded by spindle-shaped electron pockets originating from the same band.
The band bottom of both features lies at 0.5 eV below the Fermi level. From the
experimentally measured band structure, we estimate the momentum-dependent RKKY
coupling strength and demonstrate that it is peaked at the 1/2 GK wave vector.
Comparison with neutron diffraction data from the same crystals shows perfect
agreement of this vector with the propagation vector of the low-temperature
in-plane magnetic order, thereby demonstrating the decisive role of the Fermi
surface geometry in explaining the complex magnetically ordered ground state of
ternary rare earth silicides.Comment: 4 pages, 4 figure
MEDBERT.de: A Comprehensive German BERT Model for the Medical Domain
This paper presents medBERTde, a pre-trained German BERT model specifically
designed for the German medical domain. The model has been trained on a large
corpus of 4.7 Million German medical documents and has been shown to achieve
new state-of-the-art performance on eight different medical benchmarks covering
a wide range of disciplines and medical document types. In addition to
evaluating the overall performance of the model, this paper also conducts a
more in-depth analysis of its capabilities. We investigate the impact of data
deduplication on the model's performance, as well as the potential benefits of
using more efficient tokenization methods. Our results indicate that
domain-specific models such as medBERTde are particularly useful for longer
texts, and that deduplication of training data does not necessarily lead to
improved performance. Furthermore, we found that efficient tokenization plays
only a minor role in improving model performance, and attribute most of the
improved performance to the large amount of training data. To encourage further
research, the pre-trained model weights and new benchmarks based on
radiological data are made publicly available for use by the scientific
community.Comment: Keno K. Bressem and Jens-Michalis Papaioannou and Paul Grundmann
contributed equall
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