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Deciphering the Role of Vinylene Carbonate in Shaping CO Clus-ter Growth and Stability via Wavelet-Enhanced Spectroscopy
No full textThis study presents the first integration of wavelet denoising with cavity-based microwave spectroscopy to explore the for-mation and characteristics of gas-phase heterogeneous vinylene carbonate-(CO) clusters. Through this innovative ap-proach, faint spectral lines were detected with efficiency, enhancing our understanding of complex interaction patterns that govern the growth and stability of these molecular clusters. It was found that CO aggregates preferentially around the vi-nylene carbonate molecule through C···O tetrel bonds at the carbonyl and ether groups, altering the typical self-aggregation topology of free CO clusters. This leads to a more symmetrical growth around the vinylene carbonate monomer. Our find-ings provide insights into the solubility mechanisms of compounds in supercritical CO and advancing the understanding of sub-nanoscale CO aggregation patterns
Gradients in lacunar morphology and cartilage mineralization reflect the mechanical function of the mouse femoral head epiphysis
No full textMouse femurs are widely used to study bone development and disorders. The mammalian femoral head epiphysis, located between articular cartilage and a growth plate, critically maintains joint integrity during weight-bearing and supports femoral growth. Murine femoral head epiphyses are unusual in having no secondary ossification center (SOC). In this regard, a key question arises: How is the extracellular matrix (ECM) of the mouse femoral head epiphysis structured to balance the competing demands of mechanical stability and nutrient transport in the absence of a SOC? This study investigates the microstructure and ECM organization of normal young mouse femoral head epiphyses across multiple length scales and identifies distinct gradients in lacunar size, shape, mineral content, and collagen and mineral organization. Chondrocyte lacunae in deep epiphyseal zones are significantly larger, more spherical and interconnected, compared to the lacunae near the tidemark and growth plate. Enlarged lacunae and increased tissue porosity in the deep zones are associated with higher ECM mineralization, compensating for reduced stiffness from the porosity while maintaining compliance that may facilitate fluid flow and nutrient diffusion to enlarged cells. This study highlights an optimization strategy of murine proximal femoral epiphyses driven by mechanical and biological demands and it offers insights for designing engineered constructs
The synergistic strength-ductility mechanism of the in-situ constructed interfacial/intragranular hierarchical structure in nano particulate reinforced (TiB+LaO)/Ti composites
No full textThe strength-ductility trade-off has hindered the widespread application of powder metallurgy (PM) titanium matrix composites (TMCs). In-situ planting nano-particles as ultra-fine networks into the TMCs powder and constructing the interfacial/intragranular hierarchical microstructure have emerged as a promising strategy to overcome the strength-ductility trade-off. In the present work, we precisely controlled the distribution of the network nano-particles by adjusting the sintering temperatures and successfully transformed the ultrafine network into the interfacial/intragranular structure. The well-designed (TiB + LaO)/IMI834 TMCs demonstrated exceptional mechanical properties, achieving a tensile strength of 1158 MPa while maintaining an elongation exceeding 8.6 %—performance comparable to wrought TMCs without requiring thermo-mechanical processing. The dislocation evolution and the slip activation behavior were investigated by in-situ synchrotron X-ray diffraction experiments and interrupted in-situ SEM-EBSD observations, which provided new insights into the strength-ductility synergy mechanism of the interfacial/intragranular nano-particles. These studies revealed that the hierarchical structure enhanced the dislocation storage capacity while simultaneously promoting slip activation. This dual effect facilitated multi-system sliding, which effectively optimized dislocation distribution and reduced stress concentration. This study visually elucidates the synergistic strength-ductility mechanism of the interfacial/intragranular hierarchical structure and establishes a straightforward and reliable approach for manufacturing high-performance PM TMCs
Tailoring optical and ferroelectric properties in SbBi SI van der Waals chalcohalides towards solar absorber applications
No full textDie Effizienz von Solarzellen hängt von Absorbermaterialien ab, deren optische und elektronische Eigenschaften für optimale Leistung präzise eingestellt werden können. Das gemischt-anionische Van-der-Waals-Material SbSI ist ein vielversprechender Kandidat, da es sowohl eine schmale Bandlücke als auch eine starke ferroelektrische Polarisation aufweist, was zusammen einen robusten photovoltaischen Effekt und einen hohen Wirkungsgrad (PCE) ermöglicht. Wir zeigen hier, dass die Substitution von Antimon durch Bismut in SbSI eine gezielte Einstellung sowohl der Bandlücke als auch der ferroelektrischen Eigenschaften erlaubt. Ein steigender Bi-Gehalt induziert anisotrope Veränderungen in der Kristallstruktur: Die Bandlücke nimmt bei geringen Substitutionsgraden rapide ab und stabilisiert sich bei höheren Bi-Konzentrationen bei 1,5 eV. Gleichzeitig wird die Ferroelektrizität stark unterdrückt, was sich im Verschwinden von Soft-Phonon-Moden und Signalen der zweiten Harmonischen zeigt. Berechnungen auf Basis der Dichtefunktionaltheorie bestätigen die Beobachtung, dass der ferroelektrische Grundzustand durch Bi-Substitution ungünstiger wird. Dies ist auf Veränderungen der Sb/Bi–S-Bindungseigenschaften und eine damit einhergehende Verringerung der freien Elektronenpaare zurückzuführen. Die Möglichkeit, sowohl strukturelle als auch funktionelle Eigenschaften gezielt einzustellen, unterstreicht das Potenzial von Sb 1− x Bi x SI für die Entwicklung leistungsstarker Solarenergiematerialien der nächsten Generation
Correlative characterization of stereocomplex formation in blends of aliphatic polyester P(PCL m - b -PLLA n ) multiblock-copolymers and PDLA
No full textIn phase-separating multiblock copolymers it is a challenge to quantify the relationship between molecular structure and functional properties, yet this quantification is crucial for processing and applications. Here, we describe the molecular structure and phase behavior-properties relationships for a modular system of poly[(ε-caprolactone)-b-poly(L-lactide)] multiblock copolymers with well-defined long/short block lengths and their blends with poly(D-lactide) (PDLA) of varying lengths. The formation of crystallite types and sizes as well as absolute and relative crystallinities of PCL, PLA homocrystallites (HC), and PLA stereocrystallites (SC) were studied by DSC and WAXS, and visualized by TEM, POM, and AFM. We reveal that SC formation occurs in blends containing a ratio between 1 : 1 and 1 : 4 ratio of PDLA and PLLA. In systems with much longer PCL than PLLA sequence length (113 : 18), SC formation is inhibited. Blend crystallinity was highest for a medium PDLA length. SC formation is preferred over HC formation, and SCs act as nucleation points for PCL crystallization. In our work the segment length had a trend to correlate with crystallite sizes. Tensile strength (from 0.5 to 8 MPa) and elongation at break (from 10% to >750% at room temperature) could be increased simultaneously by allowing SC formation, which in the studied blends correlated with low overall crystallinity. Our study shows strategic polymer synthesis and blending for the precise control of stereocomplex formation and fine-tuning in high-performance PLA-based materials. These findings support the knowledge-based choice of blend composition and segment length to tailor versatile materials with tunable mechanical and thermal properties
N‐Type Behavior from a P‐Type Dopant: Charge Compensation Mechanisms in Trivalent Y‐Doped HfO
No full textThe current market launch of HfO -based ferroelectric devices relies on the control of the inherent oxygen vacancies (OVs) and their impact on the ferroelectric performance. Due to the necessary stabilization of the ferroelectric phase by doping, several dopants are investigated for their applicability to control the vacancy concentration. Hf mathematical equation signatures in X-ray photoemission spectra are often used as an indication of OVs for both qualitative and quantitative analysis. The analysis of Y doped HfO (Y:HfO) as investigated by hard x-ray photoelectron spectroscopy (HAXPES) reveals the inapplicability of the Hf mathematical equation signature for a quantitative determination of OVs in the case of heterovalent doping and is restricted to pure HfO or isoelectronic substitution of Hf by, for example, Zr
Improving PaNET – The ontology of Photon and Neutron Experimental Techniques
No full textIn order to build a comprehensive understanding of all kinds of materials, the Photon and Neutron (PaN) community has been developing an increasing portfolio of experimental techniques (ET). These techniques share similarities including physical processes, experimental probes, functional dependencies, or purposes. This intricate web of techniques benefits from organisation into an ontology, known as the Photon and Neutron Experimental Technique (PaNET) ontology.We aim to highlight the existing and potential applications of this ontology. One notable application is the development of a beamline finder, as demonstrated for the PETRA III synchrotron. This tool aids users in identifying beamlines that align with their specific requirements of their scientific questions. The ontology facilitates this process by providing detailed information about available methods and techniques.The techniques listed in the ontology can be integrated into experimental datasets, thus enhancing the findability of datasets and improving data accessibility. Additionally, specifying the ET during a measurement can be used to trigger metadata schemas that are tailored to a specific technique. This ensures that the captured metadata is relevant and precise, enhancing the quality and utility of the data.We present an overview of the current status of these activities, with ideas on how you can benefit from them and the opportunities for direct involvement
A search for feebly-interacting particles in decays with missing energy at Belle
No full textWe present a search for an invisible hidden-sector particle , produced in and decays, where , , , . The search is performed using collision data recorded with the Belle detector, corresponding to 711~fb. No significant signal is observed. We set 90% confidence level upper limits ranging between and on the branching fraction as a function of . Corresponding limits are set on for lifetimes between m and 10 m. Many of these limits are the first direct constraints on their respective decays. Our results provide the most stringent exclusion limits to date on the branching fractions for all search channels, and exclude previously unexplored regions of parameter space relevant to several new physics models
Multimodal synchrotron characterization of the formation and spatial distribution of retained austenite in PBF-LB/M-manufactured ferritic–martensitic steel
No full textMetal additive manufacturing is a promising route for producing complex, highly customized embeddedstructures for nuclear fusion environments, such as breeding blankets and divertors. These applicationsrequire steels with high thermomechanical stability and resistance to irradiation, yet AM processing oftenleads to undesired microstructural heterogeneities, including the formation of metastable phases. In thiswork, we investigate the formation and spatial distribution of retained austenite in Laser Powder BedFusion (PBF-LB/M) — processed ferritic–martensitic stainless steel (AISI 415) using multimodal synchrotron-based characterization. Micron-resolution 2D and 3D synchrotron X-ray Diffraction and X-ray Fluorescencemapping, combined with operando XRD during PBF-LB/M, reveal the presence of retained -phase in periodicmesostructures at concentrations up to 0.5 wt%, depending on scanning strategy. We demonstrated thatthis result, gained from volumetric measurements based on μXRD scanning imaging, cannot be gatheredby any surface-sensitive technique (e.g. EBSD) due to depth limitations and phase transformation artifactsduring sample preparation. No correlation between -phase formation and elemental segregation was observed.Operando XRD measurements show that cooling rates critically affect phase evolution: wall-like geometriesexhibit rapid cooling (∼105 to 106 K/s) and complete martensitic transformation, whereas bulk samples coolmore slowly (∼104 K/s), allowing up to 0.5 wt.% of -phase to be retained. These results demonstrate the stronginfluence of both scanning strategy and thermal history on phase stability in PBF-LB/M steels, supporting the qualification of AM-built components for nuclear applications
Influence of isothermal post-treatment on tribocorrosion behaviour of laser powder bed fusion-processed -type Ti-Nb alloy
No full textbiocompatibility.Nonetheless, their cast and solution-treated forms suffer from limited mechanical strength. LPBFprocessedTi-Nb alloys hold significant potential for customized implants. Applying post-heat treatments,particularly isothermal age-hardening, can strengthen these alloys and improve their resistance to the biomechanicalloads encountered in service. However, load-bearing implants are prone to tribocorrosion due to therelative motion between implant components or between the implant and surrounding tissue in body fluids.This study investigates the mechanical, corrosion, and tribocorrosion properties of post-treated LPBF-producedβ-type Ti-42Nb alloys, and compares their performance with both as-built LPBF Ti-42Nb and conventional Ti-6Al-4V ELI. Results show that isothermal heat treatment is effective in increasing the mechanical propertiesby introducing ωiso precipitates for Ti-42Nb (LPBF-300 ◦C 30 h) and αiso’’ precipitates for Ti-42Nb (LPBF-450 ◦C30 h) to the single β-phase microstructure. Tribocorrosion behaviour was investigated under open circuit potential(OCP) and anodic potentiostatic polarization conditions (0.6 V vs. Ag|AgCl) in phosphate-buffered saline(PBS) using a reciprocating pin-on-disk tribometer. The formation of precipitates does not adversely affect thepassive film, indicating that its stability is maintained by the strong passivating nature of Ti-Nb alloys. However,the tribocorrosion resistance declines following isothermal heat treatment, likely due to the rapid detachment ofhard and brittle precipitates, leading to increased material loss. Nevertheless, controlling the distribution ofprecipitates in LPBF-fabricated Ti-42Nb alloys may enhance their performance for implant use