Paul Scherrer Institute

RE-Ba-Cu-O (REBCO) bulk high temperature superconducting undulators have been experimentally demonstrated to generate undulator fields exceeding 2 T at a 10 mm period, outperforming alternative undulator technologies for short-period applications. This study aims to further enhance undulator performance by reducing the period length through optimization of staggered-array, half-moon-shaped REBCO bulks. We propose a novel dual-lunate-ring-based REBCO undulator geometry that enables control of magnetization currents within individual lunate rings. The coexistence of magnetization currents on both the upper and lower sides of the undulator axis contributes to a significant enhancement of the on-axis magnetic field. To evaluate the performance of this design, the undulator period and gap were fixed at 7 mm and 3.3 mm, respectively, while the dimensions of the bulk rings were optimized numerically using the H-formulation. When the background solenoidal field changes from 10T to zero (ΔBs = 10 T), the undulator is expected to achieve a field strength B0 of 1.65T with a 7 mm period, corresponding to a deflection parameter of K = 1.1.

Inconel 718 dominates laser powder bed fusion (PBF-LB/M) builds as the benchmark Ni superalloy for its γ′/γ″ hardenability, weldability, and qualification pedigree, yet its fatigue resistance remains limited by porosity, tensile residual stresses, and microstructural heterogeneity. Hot isostatic pressing (HIP) reduces porosity but induces grain growth and twinning, which degrade fatigue performance. Prior attempts to control grain size using micron-scale carbides often led to reduced ductility. We introduce a powder modification strategy for reused Inconel 718 feedstock by adding 0.6 wt.% micron-sized niobium and titanium carbides. During PBF-LB/M, these carbides dissolve and reprecipitate as nanoscale carbide-nitrides that pin grain boundaries and refine the microstructure during heat treatment. Neutron diffraction measurements reveal a redistribution of residual stresses, linked to interactions between nano-precipitates and the alloy structure. Fatigue life improves by 150–200% in the 10 5 –10 6 cycle regime, with fatigue limits up to 200 MPa higher than wrought or unmodified, additively manufactured (AM) IN718. This approach enables powder reuse while enhancing mechanical performance, offering a scalable route for fatigue-critical components in aerospace and energy sectors. By integrating powder chemistry and process control, this method demonstrates a sustainable strategy for upcycling aged AM powders into high-performance materials. • Powder-level NbC/TiC addition refines grains and suppresses HIP coarsening • Nano carbide–nitrides pin boundaries and redistribute residual stress • Fatigue life improved by 150–200% with +200 MPa fatigue limit • Compatible with existing IN718 reuse and qualification routes • Enables circular powder use and scalable fatigue-critical AM parts

Ultrafast control of functional materials by light is key for developing optoelectronic devices. Still, the mechanisms by which microscopic photoinduced excitations evolve into a macroscopic phase transformation remain poorly understood, partly due to the experimental challenges of isolating multiscale electronic and structural dynamics. Here we use femtosecond X-ray techniques to track the non-equilibrium dynamics leading to macroscopic transformation in a ferroelastic charge-transfer Prussian blue analogue. The experimental data evidence a sequence of phenomena. The initial electronic excitation leads to reverse Jahn-Teller distortion within 50 fs, causing intermetallic charge-transfer polarons within 200 fs. Polarons generate considerable lattice strain and trigger phase nucleation within 60 ps. This elastically driven cooperativity, launched by the photoinduced polarons, offers an efficient route to the generation and stabilization of photoinduced phases in many volume-changing materials.

ZUSAMMENFASSUNG Die Photopharmakologie entwickelt lichtresponsive Wirkstoffe zur gezielten Modulation von Proteinaktivitäten, die präzise und dynamische Untersuchungen ihrer Funktionen in Gesundheit und Krankheit ermöglichen. Adrenerge Rezeptoren sind hierfür besonders geeignete Ziele, da sie prototypische G‐Protein‐gekoppelte Rezeptoren mit hoher klinischer Relevanz für bronchiale und kardiovaskuläre Erkrankungen darstellen. In dieser Studie kombinierten wir die azobenzenbasierte Verbindung Photoazolol‐1 mit zeitaufgelöster serieller Kristallographie an Röntgen‐Freie‐Elektronen‐Lasern, um die molekularen Mechanismen aufzuklären, durch die photoschaltbare β‐Blocker die Aktivität des β 2 ‐Adrenozeptors (β 2 AR) modulieren. Zeitaufgelöste Strukturen des Rezeptors in Komplexen mit trans‐Photoazolol‐1 (vor der Photokonversion), einem gespannten Zwischenzustand im Nanosekundenbereich sowie vollständig photoisomerisiertem cis‐Photoazolol‐1 zeigen, wie die Isomerisierung der Azobenzeneinheit unterschiedliche konformationelle Veränderungen innerhalb der orthosterischen Ligandenbindetasche induziert. Innerhalb von Sekunden nimmt lichtangeregtes Photoazolol‐1 eine neue Bindepose ein, wodurch Wechselwirkungen mit der extrazellulären Schleife 2 verändert und die Positionen der Transmembranhelices 5, 6 und 7 verschoben werden. Funktionelle Assays des β 2 AR in zellulären Membranen belegen, dass Photoazolol‐1 als Wirksamkeits‐Photoschalter fungiert, der sich bei der Isomerisierung von einem inversen Agonisten zu einem neutralen Antagonisten wandelt, ohne die Bindetasche zu verlassen. Zusammengenommen weisen diese Ergebnisse auf einen molekularen Mechanismus der Aktivitätsmodulation durch Wirksamkeits‐Photoschalter hin und liefern einen konzeptionellen Rahmen für das Design von Liganden, die lichtgetriebene Übergänge innerhalb der Bindetasche zur räumlichen und zeitlichen Kontrolle der Rezeptorfunktion nutzen.

Motor vehicles remain a significant contributor to urban air pollution, emitting compounds in both the gas and particulate phases. While emissions under hot driving conditions have decreased due to improvements in exhaust after-treatment systems, cold starts continue to contribute disproportionately to total vehicle emissions. Furthermore, gas-phase organic compounds emitted during cold starts can be oxidized in the atmosphere, leading to the formation of secondary organic aerosol (SOA).To enhance our understanding of cold-start emissions and their potential to form SOA, measurements of approximately 21,000 cold starts were carried out inside an underground parking garage from November 29 to December 24, 2024. The garage consists of 250 parking spaces and is located beneath a shopping mall in Patras, Greece. The particle phase was measured by a scanning mobility particle sizer (SMPS) and further characterized using a high-resolution aerosol mass spectrometer (HR-ToF-AMS) and a high-resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) coupled to a CHARON inlet. Black carbon was quantified by an Aethalometer (AE33). Gas-phase composition was measured with the PTR-MS, while inorganic trace gases including NO, NO2, CO, CO2, O3, and SO2 were continuously monitored. Tenax tubes were also collected from the garage ambient air for offline GC-MS analysis. Additionally, the traffic flow was recorded at both the entrance and exit of the garage. The SOA formation from vehicle emissions was investigated using an oxidation flow reactor (OFR) under controlled OH exposures by varying combinations of the reactor’s UV lamps.The measurements of the traffic and the concentrations were combined to derive average emissions of gas and particulate phase pollutants. The estimated cold start emission factors were then compared to those reported in the Dutch Εmission Inventory. Within the OFR, organic aerosol concentrations increased from four to eleven times depending on OH exposure, with the production of highly oxygenated organic compounds. Aromatic compounds were identified as the dominant precursors of SOA.

Ocean alkalinity enhancement (OAE) is an approach for the deliberate removal of CO2 from the atmosphere. This emerging technology relies on human intervention to increase the alkalinity of seawater which, in turn, induces a net flux of atmospheric CO2 into the ocean. OAE is considered comparatively scalable and promises to deliver durable carbon removal but, to the best of our knowledge, a detailed feasibility study has not been undertaken. Key aspects to consider in such an analysis are: 1) how much alkalinity can be added at coastal outfall sites before breaching regulatory and geochemical constraints on seawater pH and carbonate saturation state, and 2) whether delivery of alkalinity can be achieved with a sufficiently low carbon footprint. We present results addressing both questions using the coast of Nova Scotia in eastern Canada as a test case. The first operational deployment of OAE started in Halifax Harbour, Nova Scotia, in October 2023. By October 2025, the climate-tech company Planetary Technologies had retired carbon credits for the removal of 1,800 tons of CO2. We ask what it would take to scale up from an annual net carbon removal of 1000 t/y of CO2 to 1 Gt/y, which is commonly considered the threshold for a carbon removal technology to be scalable. Specifically, we analyze the maximum CDR capacity of individual outfalls since this will meaningfully influence deployment strategies for OAE. Our results are based on a suite of simulations using a coupled circulation-biogeochemical model for Halifax Harbour that has been used to support OAE field work and verification of OAE credits and a prospective Life Cycle Analysis conducted for this site.