To synthetically target a specific material with select performance, the underlying relationship between structure and function must be understood. For targeting magnetic properties, such understanding is underdeveloped for a relatively new class of layered hexagonal perovskites, the 12R-BaMnO family. Here, we perform a detailed magnetostructural study of the layered hexagonal perovskite materials 12R-BaMnO, where = diamagnetic Ce or paramagnetic ≈ 1/2 Pr.
View Article and Find Full Text PDFCarbon capture can mitigate point-source carbon dioxide (CO) emissions, but hurdles remain that impede the widespread adoption of amine-based technologies. Capturing CO at temperatures closer to those of many industrial exhaust streams (>200°C) is of interest, although metal oxide absorbents that operate at these temperatures typically exhibit sluggish CO absorption kinetics and instability to cycling. Here, we report a porous metal-organic framework featuring terminal zinc hydride sites that reversibly bind CO at temperatures above 200°C-conditions that are unprecedented for intrinsically porous materials.
View Article and Find Full Text PDFPorous solids can accommodate and release molecular hydrogen readily, making them attractive for minimizing the energy requirements for hydrogen storage relative to physical storage systems. However, H adsorption enthalpies in such materials are generally weak (-3 to -7 kJ/mol), lowering capacities at ambient temperature. Metal-organic frameworks with well-defined structures and synthetic modularity could allow for tuning adsorbent-H interactions for ambient-temperature storage.
View Article and Find Full Text PDFMetathesis reactions are widely used in synthetic chemistry. While state-of-the-art organic metathesis involves highly controlled processes where specific bonds are broken and formed, inorganic metathesis reactions are often extremely exothermic and, consequently, poorly controlled. Ternary nitrides offer a technologically relevant platform for expanding synthetic control of inorganic metathesis reactions.
View Article and Find Full Text PDFA proposed low-energy alternative to the separation of alkanes from alkenes by energy-intensive cryogenic distillation is separation by porous adsorbents. Unfortunately, most adsorbents preferentially take up the desired, high-value major component alkene, requiring frequent regeneration. Adsorbents with inverse selectivity for the minor component alkane would enable the direct production of purified, reagent-grade alkene, greatly reducing global energy consumption.
View Article and Find Full Text PDFStep-shaped adsorption-desorption of gaseous payloads by flexible metal-organic frameworks can facilitate the delivery of large usable capacities with significantly reduced energetic penalties. This is desirable for the storage, transport, and delivery of H, as prototypical adsorbents require large swings in pressure and temperature to achieve usable capacities approaching their total capacities. However, the weak physisorption of H typically necessitates undesirably high pressures to induce the framework phase change.
View Article and Find Full Text PDFChem Commun (Camb)
October 2022
Through systematic linker substitution in a flexible zeolitic imidazolate framework (ZIF) with step-shaped adsorption-desorption, structural intermediates between the known open and closed phases were isolated. Reflecting this, modulative sorption behaviour with an inverting adsorption pressure trend-in which the step pressure decreases and then increases again with increasing mixed linker concentration-is observed, highlighting how linker substitution modifies the energetic landscape of framework flexibility.
View Article and Find Full Text PDFFlexible metal-organic frameworks offer a route towards high useable hydrogen storage capacities with minimal swings in pressure and temperature step-shaped adsorption and desorption profiles. Yet, the understanding of hydrogen-induced flexibility in candidate storage materials remains incomplete. Here, we investigate the hydrogen storage properties of a quintessential flexible metal-organic framework, ZIF-7.
View Article and Find Full Text PDFNaNiTeOhas a layered hexagonal structure with a honeycomb lattice constituted by Niand a chiral charge distribution of Nathat resides between the Ni layers. In the present work, the antiferromagnetic (AFM) transition temperature of NaNiTeOis confirmed at≈ 27 K, and further, it is found to be robust up to 8 T magnetic field and 1.2 GPa external pressure; and, without any frequency-dependence.
View Article and Find Full Text PDFThe spin state in heterobimetallic complexes heavily influences both reactivity and magnetism. Exerting control over spin states in main group-based heterobimetallics requires a different approach as the orbital interactions can differ substantially from that of classic coordination complexes. By deliberately engendering an energetic mismatch within the two metals in a bimetallic complex we can mimic the electronic structure of lanthanides.
View Article and Find Full Text PDFSubtle changes in chemical bonds may result in dramatic revolutions in magnetic properties in solid-state materials. MnPtP, a derivative of the rare-earth-free ferromagnetic MnPtAs, was discovered and is presented in this work. MnPtP was synthesized, and its crystal structure and chemical composition were characterized by X-ray diffraction as well as energy-dispersive X-ray spectroscopy.
View Article and Find Full Text PDFEnviron Health Perspect
September 2020
Background: Lead (Pb) is a highly toxic pollutant. Evidence suggests it is associated with cardiovascular disease (CVD)-related mortality.
Objectives: We present a rigorous approach for identifying concentration-response functions that relate adult Pb exposures to CVD mortality to inform a health impact model (HIM).
A new, air-stable, permanently porous uranium(iv) metal-organic framework U(bdc) (, bdc = 1,4-benzenedicarboxylate) was synthesized and its H and CH adsorption properties were investigated. Low temperature adsorption isotherms confirm strong adsorption of both gases in the framework at low pressures. gas-dosed neutron diffraction experiments with different D loadings revealed a rare example of cooperative framework contraction (Δ = -7.
View Article and Find Full Text PDFWe report a pressure-induced phase transition in the frustrated kagomé material jarosite at ∼45 GPa, which leads to the disappearance of magnetic order. Using a suite of experimental techniques, we characterize the structural, electronic, and magnetic changes in jarosite through this phase transition. Synchrotron powder x-ray diffraction and Fourier transform infrared spectroscopy experiments, analyzed in aggregate with the results from density functional theory calculations, indicate that the material changes from a R3[over ¯]m structure to a structure with a R3[over ¯]c space group.
View Article and Find Full Text PDFAt the Center for Addiction and Mental Health (CAMH) Integrated Day Treatment (IDT) program, each patient attends either a morning stream or an afternoon stream, but not both. We examined whether subjective chronotype, or the time of day an individual prefers to be most active and alert, predicted treatment outcomes differentially in depressed patients attending the morning vs. afternoon IDT streams.
View Article and Find Full Text PDFObjective: To evaluate the dose-response, efficacy, and safety of fluticasone furoate (FF; 25 µg, 50 µg, and 100 µg), administered once daily in the evening during a 12-week treatment period to children with inadequately controlled asthma.
Study Design: This was a Phase IIb, multicenter, stratified, randomized, double-blind, double-dummy, parallel-group, placebo- and active-controlled study in children aged 5-11 years with inadequately controlled asthma. The study comprised a 4-week run-in period, 12-week treatment period, and 1-week follow-up period.
Background: Poly-ureaurethane has been previously described for the management of dry, brittle, and in general, dystrophic nails. The polymer yields a waterproof, breathable barrier to protect the nail plate and prevent further damage to the nail, while regulating transonychial water loss (TOWL). Because nail dystrophy and dessication are contributing factors to onychomycosis, a barrier that protects the nail but also allows a topical antifungal to permeate its shield is potentially an advantageous combination.
View Article and Find Full Text PDFBackground: Inhaled corticosteroids (ICS) are effective maintenance treatments for childhood asthma; however, many children remain uncontrolled. Vilanterol (VI) is an inhaled long-acting beta-2 agonist which, in combination with the ICS fluticasone furoate, is being explored as a once-daily treatment for asthma in children. We evaluated the dose-response, efficacy, and safety of once-daily VI (6.
View Article and Find Full Text PDFPolyelectrolyte complexes present new opportunities for self-assembled soft matter. Factors determining whether the phase of the complex is solid or liquid remain unclear. Ionic polypeptides enable examination of the effects of stereochemistry on complex formation.
View Article and Find Full Text PDFThe apical sodium-dependent bile acid transporter (ASBT) transports bile salts from the lumen of the gastrointestinal (GI) tract to the liver via the portal vein. Multiple pharmaceutical companies have exploited the physiological link between ASBT and hepatic cholesterol metabolism, which led to the clinical investigation of ASBT inhibitors as lipid-lowering agents. While modest lipid effects were demonstrated, the potential utility of ASBT inhibitors for treatment of type 2 diabetes has been relatively unexplored.
View Article and Find Full Text PDFPhospholipase C (PLC) enzymes are an important family of regulatory proteins involved in numerous cellular functions, primarily through hydrolysis of the polar head group from inositol-containing membrane phospholipids. U73122 (1-(6-((17β-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione), one of only a few small molecules reported to inhibit the activity of these enzymes, has been broadly applied as a pharmacological tool to implicate PLCs in diverse experimental phenotypes. The purpose of this study was to develop a better understanding of molecular interactions between U73122 and PLCs.
View Article and Find Full Text PDFBile acid sequestrants (BAS) have shown antidiabetic effects in both humans and animals but the underlying mechanism is not clear. In the present study, we evaluated cholestyramine in Zucker diabetic fatty (ZDF) rats. Although control ZDF rats had continuous increases in blood glucose and hemoglobin A1c (HbA1c) and serum glucose and a decrease in serum insulin throughout a 5-week study, the cholestyramine-treated ZDF rats showed a dose-dependent decrease and normalization in serum glucose and HbA1c.
View Article and Find Full Text PDFPhospholipase C-gamma (PLC-gamma) is stimulated by epidermal growth factor via activation of the epidermal growth factor receptors. The PLC inhibitor, 3-nitrocoumarin (3-NC), selectively inhibited PLC-gamma in Madin-Darby canine kidney cells without affecting the activity of PLC-beta. In contrast, inhibitors of PLC-beta, hexadecylphosphocholine and, had no effect on the activity of PLC-gamma.
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