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Overview of the European supercritical-water-cooled small modular reactor concept
No full textThis paper presents the European Supercritical-Water-Cooled Small Modular Reactor (SCW-SMR) concept developed within the ECC-SMART project, a joint European-Canadian-Chinese initiative. The 290 MWth reactor operates at 25 MPa with a core outlet temperature of 500 °C, achieving 44 % net thermal efficiency. The innovative horizontal fuel-assembly arrangement with seven heat-up stages and intermediate mixing plenums enables fully passive decay heat removal through natural circulation, even without operator intervention or external power for >72 hours. The compact pressure vessel (4.17 m inner diameter) contains 400 fuel assemblies in a 20×20 square lattice. System-level safety analyses demonstrate that all design-basis accidents are mitigated exclusively by passive systems, eliminating the need for high-pressure injection. The large subcooled water inventory and unique in-vessel natural circulation patterns limit peak cladding temperatures to <625 °C in normal operation and <780 °C during accidents. By integrating the high efficiency of supercritical-water cooling with inherently safe, fully passive features, the ECC-SMART SCW-SMR offers a promising Generation IV solution tailored to European energy and safety requirements
Gold mobility in Archean metasedimentary belts: Implications for orogenic gold deposits
No full textThe southern Superior Province (Canada) comprises large metasedimentary belts, such as the Pontiac and Quetico subprovinces, adjacent to Au-endowed greenstone belts. The Pontiac sedimentary rocks have been proposed as a source of Au for the highly endowed southern Abitibi greenstone belt. However, a comparison with sedimentary rocks adjacent to poorly endowed greenstone belts is lacking. Here we examine a suite of metasedimentary and minor volcanic rocks collected from three transects in the Pontiac and Quetico metasedimentary belts adjacent to greenstone belts with variable Au endowments. We combine in situ Au data of sulfides in metasedimentary rocks with whole-rock ultra-low-detection Au data. Gold concentrations decrease across metamorphic isograds in the well- and moderately endowed transects, while limited Au mobility is observed in the poorly endowed transect. The release of Au from metasedimentary rocks is linked to the pyrite-pyrrhotite transition. This reaction is incomplete in the poorly endowed transect, explaining the limited Au mobility observed. Our data reveal a spatial correlation between Au mobility in metasedimentary belts and Au endowment in the adjacent greenstone belts
Pulse-energy-scaling of a Tm-based 3×3-coupler NALM at 2000 nm
No full textWe report the first noise-like mode-locked (NLML), high-pulse-energy, low-repetition-rate Tm-doped fiber laser based on a 3×3-coupler nonlinear amplifying loop mirror (NALM) at 2 µm. The effect of cavity length changes on energy scaling is investigated in an all-fiber, all-polarization-maintaining configuration, yielding 2 ns pulses with energies up to 33 nJ. In addition, the laser exhibits harmonic noise-like mode-locking (HNLML) and broadband supercontinuum generation spanning 1.95 to 2.25 µm at elevated pump powers
Toward Understanding Prolate 4f Monomers: Numerical Predictions and Experimental Validation of Electronic Properties and Slow Relaxation in a Muffin-Shaped Er Complex
No full textWe report the synthesis, crystal structure, and magnetic properties of the muffin-shaped complex [Er(PPTMP)(HO)][OTf] (PPTMP = (4-(6-(1,10-phenanthrolin-2-yl)pyridin-2-yl)-1H-1,2,3-triazol-1-yl)methyl pivalate) (1). Complex 1 is shown to exhibit field-induced slow relaxation of the magnetization at B = 0.1 T via two distinct relaxation paths. Using tunable high-frequency/high-field electron paramagnetic resonance spectroscopy, we experimentally determine the effective g-factors and zero field splittings (ZFS) of the two energetically lowest Kramers doublets (KD). Our data reveal that the distorted muffin-shaped ligand field favors an m ≃ ±9/2 magnetic ground state, while the main contribution to the first excited KD at Δ = 780(5) GHz is suggested to be m ≃ ±5/2. The ground state g-tensor has generally an axial form but hosts significant transversal components, which we conclude to be the source of single molecule magnet (SMM)-silent behavior in zero field. Our findings are backed up by ab initio spin–orbit configuration interaction calculations showing excellent agreement with the experimental data and, in particular, highlight that the counterions should be included in the numerical modeling of the crystalline structure
Tribological performance improvement of titanium through laser-induced oxygen and nitrogen incorporation: experimental and molecular dynamics study
No full textTitanium and its alloys have a pronounced tendency for adhesive wear and surface degradation under mechanical stress, severely limiting their widespread application in machine elements and components. A durable and efficient surface treatment for improving their wear resistance remains a major challenge. This study puts forward a cost-effective laser surface modification technique to enhance the tribological properties of commercially pure α-titanium (grade 1) by introducing interstitial oxygen and nitrogen. The process involves melting the titanium surface with a nanosecond pulsed laser in air, nitrogen, or argon atmosphere, followed by a smoothening step in argon atmosphere. Comprehensive characterisation using X-ray diffraction, electron microscopy, nanoindentation, and tribological testing reveals that interstitial oxygen and nitrogen significantly increase surface hardness and suppress adhesive wear by saturating titanium’s valence bonds and reducing surface reactivity. The modified surfaces exhibit improved wear resistance and more stable friction behaviour under lubricated conditions, with minimal running-in and wear volume. The increased wear resistance has its origins at the atomic scale and is attributed to the role of oxygen and nitrogen occupying interstitial positions in the titanium lattice, as well as grain boundary deformation, as suggested by molecular dynamics simulations of nanoscratching. The merged experimental and computational approach establishes a solid foundation for tailored surface engineering strategies that optimise titanium’s wear performance for future engineering applications
Glycation of pea protein isolate with different mannooligosaccharides to improve solubility
No full textDue to the increasing demand for plant based proteins in food products, research is being carried out to improve the functional properties of pea protein. Here, the glycation of pea protein isolate (PPI) with mannooligosaccharides (MOS) was studied, with the aim to increase solubility. Various MOS were released by enzymatic hydrolysis of galactomannans and separated into four fractions according to their degree of polymerization (DP; DP of 2, 3, 7–9 and ≥ 9). MOS reacted with PPI under controlled conditions via the Maillard reaction. Different reaction times were tested for the MOS fractions to vary the extent of glycation and the progress of the Maillard reaction. Thus, the color and the decrease in free amino groups were measured, and gel electrophoresis was performed to observe the change in molecular weight of the proteins. Based on the results, MOS fractions with a DP of 7–9 and ≥ 9 and reactions times of 24–48 h, respectively, were classified as promising due to a moderate decrease in free amino groups and only a slight change in color. Differently, glycation with mannobiose and mannotriose resulted in advanced glycation and was considered unsuitable. The solubility of the glycated proteins was determined at a pH of 3.5 and 7.0. Under neutral conditions, solubility did not change as a result of glycation. However, under acidic conditions, glycation increased the solubility of the pea proteins from 26% to about 46%
Towards Realistic Experimental Conditions for Validation of Effective Resonator Cooling in Multi-MW CW Gyrotrons
No full textRABus Footage
No full textRABus Footage: Allgemeine Videos RABus - Reallabor für den Automatisierten Busbetrieb im ÖPNV in der Stadt und auf dem Lan
Weltraumwetter und seine Auswirkungen – Wissensstand und Forschungsbedarfe
No full textWeltraumwetter beschreibt die Wechselwirkung zwischen Aktivitäten der Sonne, Sonnenwinden, -eruptionen und koronalen Masseauswürfen mit der Erde. Die Aktivitäten folgen einem 11-jährigen Zyklus, wobei ab 2030 wieder Zyklen mit einem höheren Aktivitätsniveau erwartet werden. Wenn erhöhte elektromagnetische Strahlung sowie Plasmawolken auf die Erde treffen und mit dem Erdmagnetfeld sowie der Atmosphäre interagieren, können Risiken für technische Infrastrukturen (Satelliten, Stromnetze, Unterseedatenkabel und große metallische Infrastrukturen) sowie die menschliche Gesundheit resultieren.
Zentral für eine frühzeitige Warnung und die Umsetzung von Schutzmaßnahmen sind die Beobachtung der Sonnenaktivitäten, einschließlich einer Echtzeit-Datenanalyse, die Modellierung und Simulation von geomagnetischen Stürmen sowie eine Risikoanalyse der Auswirkungen auf kritische Infrastruktursysteme. Realisiert werden die Erforschung und die Weiterentwicklung von Klassifikationssystemen, Modellen und Simulationen unter Beteiligung verschiedener deutscher Akteure. Die aktuelle deutsche Raumfahrtstrategie betont die Bedeutung einer vertieften Auseinandersetzung mit Weltraumwetter und einem Ausbau der nationalen Kapazitäten und Kenntnisse auch, um unabhängiger von US-amerikanischen Akteuren zu werden und die Souveränität Deutschlands und Europas zu erhöhen.
Obwohl die Wahrscheinlichkeit, dass Deutschland von den Auswirkungen eines geomagnetischen Sturms direkt betroffen sein wird, gering ist, fehlt bislang eine Analyse potenzieller wirtschaftlicher und gesellschaftlicher Schäden sowie des Nutzens durch verstärkte Investitionen in Beobachtungs- und Frühwarnsysteme