Unlike secondary mitral regurgitation (MR) in the setting of left ventricular (LV) disease, the occurrence of functional MR in atrial fibrillation (AF) and/or heart failure with preserved ejection ...fraction (HFpEF) has remained largely unspoken. LV size and systolic function are typically normal, whereas isolated mitral annular dilation and inadequate leaflet adaptation are considered mechanistic culprits. Moreover, the role of left atrial and annular dynamics in provoking MR is often underappreciated. Because of this peculiar pathophysiology, atrial functional MR benefits from a different approach compared with secondary MR. Although both AF and HFpEF-two closely related disease epidemics of the 21st century-are held responsible, current guidelines do not emphasize the need to differentiate atrial functional MR from (ventricular) secondary MR. This review summarizes the prevalence and prognostic importance of atrial functional MR, providing mechanistic insights compared with those of secondary MR and suggesting potential therapeutic targets.
Silicon as a negative electrode material for lithium-ion batteries has attracted tremendous attention due to its high theoretical capacity, and fluoroethylene carbonate (FEC) was used as an ...electrolyte additive, which significantly improved the cyclability of silicon-based electrodes in this study. The decomposition of the FEC additive was investigated by synchrotron-based X-ray photoelectron spectroscopy (PES) giving a chemical composition depth-profile. The reduction products of FEC were found to mainly consist of LiF and −CHF–OCO2-type compounds. Moreover, FEC influenced the lithium hexafluorophosphate (LiPF6) decomposition reaction and may have suppressed further salt degradation. The solid electrolyte interphase (SEI) formed from the decomposition of ethylene carbonate (EC) and diethyl carbonate (DEC), without the FEC additive present, covered surface voids and lead to an increase in polarization. However, in the presence of FEC, which degrades at a higher reduction potential than EC and DEC, instantaneously a conformal SEI was formed on the silicon electrode. This stable SEI layer sufficiently limited the emergence of large cracks and preserved the original surface morphology as well as suppressed the additional SEI formation from the other solvent. This study highlights the vital importance of how the chemical composition and morphology of the SEI influence battery performance.
Highly active and low-cost electrocatalysts for water oxidation are required due to the demands on sustainable solar fuels; however, developing highly efficient catalysts to meet industrial ...requirements remains a challenge. Herein, we report a monolayer of nickel-vanadium-layered double hydroxide that shows a current density of 27 mA cm(-2) (57 mA cm(-2) after ohmic-drop correction) at an overpotential of 350 mV for water oxidation. Such performance is comparable to those of the best-performing nickel-iron-layered double hydroxides for water oxidation in alkaline media. Mechanistic studies indicate that the nickel-vanadium-layered double hydroxides can provide high intrinsic catalytic activity, mainly due to enhanced conductivity, facile electron transfer and abundant active sites. This work may expand the scope of cost-effective electrocatalysts for water splitting.
Low‐toxic bismuth‐based perovskites are prepared for the possible replacement of lead perovskite in solar cells. The perovskites have a hexagonal crystalline phase and light absorption in the visible ...region. A power conversion efficiency of over 1% is obtained for a solar cell with Cs3Bi2I9 perovskite, and it is concluded that bismuth perovskites have very promising properties for further development in solar cells.
Two-dimensional transthoracic echocardiography is the most widely used noninvasive imaging modality for the evaluation and diagnosis of cardiac pathology. However, because of the physical properties ...of ultrasound waves and specifics in ultrasound image reconstruction, cardiologists are often confronted with ultrasound image artifacts. It is particularly important to recognize such artifacts in order to avoid misdiagnosis of conditions ranging from aortic dissection to thrombosis and endocarditis. This overview article summarizes the most common image artifacts encountered in routine clinical practice, along with explanations of their physical mechanisms and guidance in avoiding their misinterpretation.
Secondary mitral valve regurgitation (MR) remains a challenging problem in the diagnostic workup and treatment of patients with heart failure. Although secondary MR is characteristically dynamic in ...nature and sensitive to changes in ventricular geometry and loading, current therapy is mainly focused on resting conditions. An exercise-induced increase in secondary MR, however, is associated with impaired exercise capacity and increased mortality. In an era where a multitude of percutaneous solutions are emerging for the treatment of patients with heart failure, it becomes important to address the dynamic component of secondary MR during exercise as well. A critical reappraisal of the underlying disease mechanisms, in particular the dynamic component during exercise, is of timely importance. This review summarizes the pathophysiological mechanisms involved in the dynamic deterioration of secondary MR during exercise, its functional and prognostic impact, and the way current treatment options affect the dynamic lesion and exercise hemodynamics in general.
Lead halide perovskites have over the past few years attracted considerable interest as photo absorbers in PV applications with record efficiencies now reaching 22%. It has recently been found that ...not only the composition but also the precise stoichiometry is important for the device performance. Recent reports have, for example, demonstrated small amount of PbI2 in the perovskite films to be beneficial for the overall performance of both the standard perovskite, CH3NH3PbI3, as well as for the mixed perovskites (CH3NH3) x (CH(NH2)2)(1–x)PbBr y I(3–y). In this work a broad range of characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photo electron spectroscopy (PES), transient absorption spectroscopy (TAS), UV–vis, electroluminescence (EL), photoluminescence (PL), and confocal PL mapping have been used to further understand the importance of remnant PbI2 in perovskite solar cells. Our best devices were over 18% efficient, and had in line with previous results a small amount of excess PbI2. For the PbI2-deficient samples, the photocurrent dropped, which could be attributed to accumulation of organic species at the grain boundaries, low charge carrier mobility, and decreased electron injection into the TiO2. The PbI2-deficient compositions did, however, also have advantages. The record V oc was as high as 1.20 V and was found in PbI2-deficient samples. This was correlated with high crystal quality, longer charge carrier lifetimes, and high PL yields and was rationalized as a consequence of the dynamics of the perovskite formation. We further found the ion migration to be obstructed in the PbI2-deficient samples, which decreased the JV hysteresis and increased the photostability. PbI2-deficient synthesis conditions can thus be used to deposit perovskites with excellent crystal quality but with the downside of grain boundaries enriched in organic species, which act as a barrier toward current transport. Exploring ways to tune the synthesis conditions to give the high crystal quality obtained under PbI2-poor condition while maintaining the favorable grain boundary characteristics obtained under PbI2-rich conditions would thus be a strategy toward more efficiency devices.
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