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Chemical Long-Range Disorder in Prussian Blue Analogues for Potassium Storage
Ordered Prussian blue analogues (PBAs) are vital cathode materials for ion storage, but strong interactions between the framework and host ions, especially large ions like K + , hinder ion migration, leading to poor diffusion kinetics and reduced reaction activity. Here, in this study, we present an approach to overcome this challenge by constructing chemical long-range disorder (LRD) in PBAs, involving maintaining inherent local coordination while introducing disorder over long-range spatial dimensions. Order control is achieved by introducing a large-sized lattice to disrupt the original lattice growth during synthesis. Unlike traditional monocrystalline particles, the abundant grain boundaries in the obtained LRD structure create significant potential fluctuations, generating additional electric fields that enhance ion transport. Furthermore, the short lattice coherence length reduces interaction between the framework and K + . These factors collectively contribute to the improved electrochemical activity of LRD PBAs during K + storage. This finding opens new avenues for designing PBA structures and offers insights into their structure-electrochemical performance relationship.
Stabilization of hexazine rings in potassium polynitride at high pressure
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Helium atom scattering from potassium tantalate/niobate(001) surfaces
The specular diffraction intensity of helium atoms from KTa 0.48 Nb 0.52 O 3 surfaces undergoes dramatic fluctuations as a function of surface temperature.
Measurement of the angular dependence of the spontaneous Raman scattering in anisotropic crystalline materials using spherical samples: Potassium dihydrogen phosphate as a case example
A specialized experimental configuration was created to allow for more-accurate characterization of the spontaneous Raman scattering properties in anisotropic materials. This need stems from the challenges, arising from the complexity of light propagation, in obtaining accurate measurements of the angular dependence of the Raman scattering cross section in birefringent materials. The nonlinear optical material KH 2 PO 4 (KDP) is used as a model medium. Our report is motivated by the need to improve our understanding and management of transverse stimulated Raman scattering in KDP crystals and its deuterated analog, DKDP, typically used for frequency conversion and polarization control in large-aperture laser systems. Key to this experimental platform is the use of high-quality spherical samples that enable one to measure the Raman scattering cross section in a wide range of geometries using only a single sample. The effect of polarization rotation of both the pump light and the collected Raman signal must be carefully considered in data analysis and can give rise to artifacts, which can, in part, be mitigated by reducing the input and collection cone angles.
Cesium exhibits different mesoscale segregation and ion pairing than lithium, sodium, or potassium in concentrated alkaline aqueous nitrite solutions
Understanding ion pairing in concentrated alkaline electrolytes facilitates the prediction and control of chemical processes in nuclear waste. While sodium is the dominant alkali metal in such systems, cesium often exhibits distinct bulk behavior relative to lighter alkali cations. Aqueous mixtures of cesium hydroxide and sodium nitrite were compared to alkali hydroxide analogs using small-angle x-ray scattering, revealing that cesium disrupts the sodium nitrite electrolyte structure, forming cesium-rich domains. This mesoscale segregation contrasts with the near-ideal mixing observed in other mixed hydroxide–nitrite systems. Raman spectroscopy indicates cesium–nitrite ion pairing, evidenced by vibrational shifts distinct from those associated with sodium. Multinuclear magnetic resonance spectroscopy further supports cesium–nitrite and cesium–hydroxide association, revealing a distinct local environment for nitrite in cesium-containing solutions. Together, these findings show that cesium promotes a unique solution structure dominated by specific ion pairing within segregated domains. This structural organization may influence radical generation pathways in high-ionic-strength alkaline media relevant to nuclear waste processing and management.
Epitaxial Growth of Cesium Potassium Antimonide Photocathode
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Selectivity filter ion binding affinity determines inactivation in a potassium channel
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Design and structural basis of selective 1,4-dihydropyridine inhibitors of the calcium-activated potassium channel K Ca 3.1
The 1,4-dihydropyridines, drugs with well-established bioavailability and toxicity profiles, have proven efficacy in treating human hypertension, peripheral vascular disorders, and coronary artery disease. Every 1,4-dihydropyridine in clinical use blocks L-type voltage-gated calcium channels. We now report our development, using selective optimization of a side activity (SOSA), of a class of 1,4-dihydropyridines that selectively and potently inhibit the intermediate-conductance calcium-activated K + channel K Ca 3.1, a validated therapeutic target for diseases affecting many organ systems. One of these 1,4-dihydropyridines, DHP-103, blocked K Ca 3.1 with an IC 50 of 6 nM and exhibited exquisite selectivity over calcium channels and a panel of >100 additional molecular targets. Using high-resolution structure determination by cryogenic electron microscopy together with mutagenesis and electrophysiology, we delineated the drug binding pocket for DHP-103 within the water-filled central cavity of the K Ca 3.1 channel pore, where bound drug directly impedes ion permeation. DHP-103 inhibited gain-of-function mutant K Ca 3.1 channels that cause hereditary xerocytosis, suggesting its potential use as a therapeutic for this hemolytic anemia. In a rat model of acute ischemic stroke, the second leading cause of death worldwide, DHP-103 administered 12 h postischemic insult in proof-of-concept studies reduced infarct volume, improved balance beam performance (measure of proprioception) and decreased numbers of activated microglia in infarcted areas. K Ca 3.1-selective 1,4-dihydropyridines hold promise for the many diseases for which K Ca 3.1 has been experimentally confirmed as a therapeutic target.
Testing for isospin symmetry breaking by combining isotope shift measurements with precise calculations in potassium
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Electromagnetic backgrounds and potassium-42 activity in the DEAP-3600 dark matter detector
The DEAP-3600 experiment is searching for weakly interacting massive particles dark matter with a 3.3 × 10 3 kg single phase liquid argon (LAr) target, located 2.1 km underground at SNOLAB. The experimental signature of dark matter interactions is kilo electron volt–scale 40 Ar nuclear recoils producing 128 nm LAr scintillation photons observed by photomultiplier tubes. The largest backgrounds in DEAP-3600 are electronic recoils (ERs) induced by β and γ rays originating from internal and external radioactivity in the detector material. A background model of the ER interactions in DEAP-3600 was developed and is described in this work. The model is based on several components which are expected from radioisotopes in the LAr, from ex situ material assay measurements, and from dedicated independent in situ analyses. This prior information is used in a Bayesian fit of the ER components to a 247.2 d dataset to model the radioactivity in the surrounding detector materials. Pulse-shape discrimination separates ER and NR events. However, detailed knowledge of the ER background and activity of detector components sets valuable constraints on NR backgrounds including neutrons and alphas. In addition, the activity of 42 Ar in LAr in DEAP-3600 is determined by measuring the daughter decay of 42 K. Finally, this cosmogenically activated trace isotope is a relevant background at higher energies for other rare event searches using atmospheric argon, e.g., DarkSide-20k, GERDA, or LEGEND. The specific activity of 42 Ar in the atmosphere is found to be 40.4 ± 5.9 μ Bq/kg of argon.