The prevalence and clinical significance of right ventricular (RV) systolic dysfunction (RVD) in patients with heart failure and preserved ejection fraction (HFpEF) are not well characterized.
...Consecutive, prospectively identified HFpEF (Framingham HF criteria, ejection fraction ≥50%) patients (n=562) from Olmsted County, Minnesota, underwent echocardiography at HF diagnosis and follow-up for cause-specific mortality and HF hospitalization. RV function was categorized by tertiles of tricuspid annular plane systolic excursion and by semiquantitative (normal, mild RVD, or moderate to severe RVD) 2-dimensional assessment. Whether RVD was defined by semiquantitative assessment or tricuspid annular plane systolic excursion ≤15 mm, HFpEF patients with RVD were more likely to have atrial fibrillation, pacemakers, and chronic diuretic therapy. At echocardiography, patients with RVD had slightly lower left ventricular ejection fraction, worse diastolic dysfunction, lower blood pressure and cardiac output, higher pulmonary artery systolic pressure, and more severe RV enlargement and tricuspid valve regurgitation. After adjustment for age, sex, pulmonary artery systolic pressure, and comorbidities, the presence of any RVD by semiquantitative assessment was associated with higher all-cause (hazard ratio=1.35; 95% confidence interval, 1.03-1.77; P=0.03) and cardiovascular (hazard ratio=1.85; 95% confidence interval, 1.20-2.80; P=0.006) mortality and higher first (hazard ratio=1.99; 95% confidence interval, 1.35-2.90; P=0.0006) and multiple (hazard ratio=1.81; 95% confidence interval, 1.18-2.78; P=0.007) HF hospitalization rates. RVD defined by tricuspid annular plane systolic excursion values showed similar but weaker associations with mortality and HF hospitalizations.
In the community, RVD is common in HFpEF patients, is associated with clinical and echocardiographic evidence of more advanced HF, and is predictive of poorer outcomes.
The fundamental properties and ultimate performance limits of organolead trihalide MAPbX3 (MA = CH3NH3+; X = Br– or I–) perovskites remain obscured by extensive disorder in polycrystalline MAPbX3 ...films. We report an antisolvent vapor-assisted crystallization approach that enables us to create sizable crack-free MAPbX3 single crystals with volumes exceeding 100 cubic millimeters. These large single crystals enabled a detailed characterization of their optical and charge transport characteristics. We observed exceptionally low trap-state densities on the order of 109 to 1010 per cubic centimeter in MAPbX3 single crystals (comparable to the best photovoltaic-quality silicon) and charge carrier diffusion lengths exceeding 10 micrometers. These results were validated with density functional theory calculations.
Radiation detection, using materials to convert high-energy photons to low-energy photons (X-ray imaging) or electrical charges (X-ray detector), has become essential for a wide range of applications ...including medical diagnostic technologies, computed tomography, quality inspection and security, etc. Metal halide perovskite-based high-resolution scintillation-imaging screens or direct conversion detectors are promising candidates for such applications, because they have high absorption cross sections for X-rays due to their heavy atom (e.g., Pb2+, Bi3+, I–) compositions; moreover, these materials are solution-processable at low temperature, possessing tunable bandgaps, near-unity photoluminescence quantum yields, low trap density, high charge carrier mobility, and fast photoresponse. In this review, we explore and decipher the working mechanism of scintillators and direct conversion detectors as well as the key advantages of halide perovskites for both detection approaches. We further discuss the recent advancements in this promising research area, pointing out the remaining challenges and our perspective for future research directions toward perovskite-based X-ray applications.
Atomic-Level Doping of Metal Clusters Ghosh, Atanu; Mohammed, Omar F; Bakr, Osman M
Accounts of chemical research,
12/2018, Letnik:
51, Številka:
12
Journal Article
Recenzirano
Odprti dostop
Conspectus Atomically precise noble metal (mainly silver and gold) nanoclusters are an emerging category of promising functional materials for future applications in energy, sensing, catalysis, and ...nanoelectronics. These nanoclusters are protected by ligands such as thiols, phosphines, and hydride and have sizes between those of atoms and plasmonic nanoparticles. In metallurgy, the properties of a pure metal are modified by the addition of other metals, which often offers augmented characteristics, making them more utilizable for real-life applications. In this Account, we discuss how the incorporation of various metal atoms into existing protected nanoclusters tunes their structure and properties. The process of incorporating metals into an existing cluster is known as doping; the product is known as a doped cluster, and the incorporated metal atom is called a dopant/foreign atom. We first present a brief historical overview of protected clusters and the need for doping and explain (with examples) the difference between an “alloy” and a “doped” cluster, which are two frequently confused terms. We then discuss several commonly observed challenges in the synthesis of doped clusters: (i) doping produces a mixture of compositions that prevents the growth of single crystals; (ii) doping with foreign atoms sometimes changes the overall composition and structure of the parent cluster; and (iii) doping beyond a certain number of foreign atoms decomposes the doped cluster. After delineating the challenges, we review a few potential synthetic methods for doped clusters: (i) the co-reduction method, (ii) the galvanic exchange method, (iii) ligand-induced conversion of bimetallic clusters to doped clusters, and (iv) intercluster reactions. As a foreign atom is able to occupy different positions within the structure of the parent cluster, we examine the structural relationship between the parent clusters and their different foreign-atom-doped clusters. We then show how doping enhances the stability, luminescence, and catalytic properties of clusters. The enhancement factor highly depends on the number and nature of the foreign atoms, which can also alter the charge state of the parent cluster. Atomic-level doping of foreign atoms in the parent cluster is confirmed by high-resolution electrospray ionization and matrix-assisted laser desorption ionization mass spectrometry techniques and single-crystal X-ray diffraction methods. The photophysical properties of the doped clusters are investigated using both time-dependent and steady-state luminescence and optical absorption spectroscopies. After presenting an overview of atomic-level doping in metal clusters and demonstrating its importance for enriching the chemistry and photophysics of clusters and extending their applications, we conclude this Account with a brief perspective on the field’s future.
This review article presents and discusses the recent progress made in the stabilization, protection, improvement, and design of halide perovskite‐based photocatalysts, photoelectrodes, and devices ...for solar‐to‐chemical fuel conversion. With the target of water splitting, hydrogen iodide splitting, and CO2 reduction reactions, the strategies established for halide perovskites used in photocatalytic particle‐suspension systems, photoelectrode thin‐film systems, and photovoltaic‐(photo)electrocatalysis tandem systems are organized and introduced. Moreover, recent achievements in discovering new and stable halide perovskite materials, developing protective and functional shells and layers, designing proper reaction solution systems, and tandem device configurations are emphasized and discussed. Perspectives on the future design of halide perovskite materials and devices for solar‐to‐chemical fuel conversion are provided. This review may serve as a guide for researchers interested in utilizing halide perovskite materials for solar‐to‐chemical fuel conversion.
The advancements made in the development of halide perovskites in photocatalyst particle‐suspension systems, photoelectrode thin‐film systems, and photovoltaic‐(photo)electrocatalysis systems for solar‐to‐chemical fuel conversion are reviewed. The syntheses and modification strategies established for yielding stable and efficient halide perovskites as well as the design of device configurations for water splitting, hydrogen iodide splitting, and CO2 reduction are highlighted and discussed.
Solar‐driven methanation represents a potentially cost‐efficient and environmentally friendly route for the direct hydrogenation of CO2. Recently, photothermal catalysis, which involves the ...combination of both photochemical and thermochemical pathways, has emerged as a promising strategy for the production of solar fuels. For a photothermal catalyst to efficiently convert CO2 under illumination, in the absence of external heating, effective light harvesting, an excellent photothermal conversion and efficient active sites are required. Here, a new composite catalyst consisting of Ni nanoparticles supported on barium titanate that, under optimal reaction conditions, is able to hydrogenate CO2 to CH4 at nearly 100% selectivity with production rates as high as 103.7 mmol g–1 h–1 under both UV–visible and visible irradiation (production rate: 40.3 mmol g−1 h–1) is reported. Mechanistic studies suggest that reaction mostly proceeds through a nonthermal hot‐electron‐driven pathway, with a smaller thermal contribution.
The present paper reports complete photothermal CO2 conversion to methane using a new composite catalyst based on Ni nanoparticles supported on barium titanate. Under optimal conditions, the photocatalyst displays an outstanding CH4 production rate of 103.7 mmol g−1 h−1 derived from its excellent photothermal performance and light harvesting properties.
A luminescent Zr(IV)-based metal–organic framework (MOF), with the underlying fcu topology, encompassing a π-conjugated organic ligand with a thiadiazole functionality, exhibits an unprecedented low ...detection limit of 66 nM for amines in aqueous solution. Markedly, this ultralow detection is driven by hydrogen-bonding interactions between the linker and the hosted amines. This observation is supported by density functional theory (DFT) calculations, which clearly corroborate the suppression of the twisting motion of thiadiazole core in the presence of amine, reducing significantly the nonradiative recombination pathways and subsequently enhancing the emission intensity. Credibly, nicotine regarded as a harmful chemical and bearing an amine pending group is also detected with high sensitivity, positioning this MOF as a potential sensor for practical environmental applications. This finding serves also as a benchmark to understand the sensing mechanism in MOFs.
Conspectus Over the past decade, the impressive development of metal halide perovskites (MHPs) has made them leading candidates for applications in photovoltaics (PVs), X-ray scintillators, and ...light-emitting diodes (LEDs). Constructing MHP nanocrystals (NCs) with promising optoelectronic properties using a low-cost approach is critical to realizing their commercial potential. Self-assembly and regrowth techniques provide a simple and powerful “bottom-up” platform for controlling the structure, shape, and dimensionality of MHP NCs. The soft ionic nature of MHP NCs, in conjunction with their low formation energy, rapid anion exchange, and ease of ion migration, enables the rearrangement of their overall appearance via self-assembly or regrowth. Because of their low formation energy and highly dynamic surface ligands, MHP NCs have a higher propensity to regrow than conventional hard-lattice NCs. Moreover, their self-assembly and regrowth can be achieved simultaneously. The self-assembly of NCs into close-packed, long-range-ordered mesostructures provides a platform for modulating their electronic properties (e.g., conductivity and carrier mobility). Moreover, assembled MHP NCs exhibit collective properties (e.g., superfluorescence, renormalized emission, longer phase coherence times, and long exciton diffusion lengths) that can translate into dramatic improvements in device performance. Further regrowth into fused MHP nanostructures with the removal of ligand barriers between NCs could facilitate charge carrier transport, eliminate surface point defects, and enhance stability against moisture, light, and electron-beam irradiation. However, the synthesis strategies, diversity and complexity of structures, and optoelectronic applications that emanate from the self-assembly and regrowth of MHPs have not yet received much attention. Consequently, a comprehensive understanding of the design principles of self-assembled and fused MHP nanostructures will fuel further advances in their optoelectronic applications. In this Account, we review the latest developments in the self-assembly and regrowth of MHP NCs. We begin with a survey of the mechanisms, driving forces, and techniques for controlling MHP NC self-assembly. We then explore the phase transition of fused MHP nanostructures at the atomic level, delving into the mechanisms of facet-directed connections and the kinetics of their shape-modulation behavior, which have been elucidated with the aid of high-resolution transmission electron microscopy (HRTEM) and first-principles density functional theory calculations of surface energies. We further outline the applications of assembled and fused nanostructures. Finally, we conclude with a perspective on current challenges and future directions in the field of MHP NCs.
Single crystals of methylammonium lead trihalide perovskites (MAPbX3; MA = CH3NH3(+), X = Br(-) or I(-)) have shown remarkably low trap density and charge transport properties; however, growth of ...such high-quality semiconductors is a time-consuming process. Here we present a rapid crystal growth process to obtain MAPbX3 single crystals, an order of magnitude faster than previous reports. The process is based on our observation of the substantial decrease of MAPbX3 solubility, in certain solvents, at elevated temperatures. The crystals can be both size- and shape-controlled by manipulating the different crystallization parameters. Despite the rapidity of the method, the grown crystals exhibit transport properties and trap densities comparable to the highest quality MAPbX3 reported to date. The phenomenon of inverse or retrograde solubility and its correlated inverse temperature crystallization strategy present a major step forward for advancing the field on perovskite crystallization.
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