Sequential Effect of Dual-Layered Hybrid Graphite Anodes on Electrode Utilization During Fast-Charging Li-Ion Batteries.

To recharge lithium-ion batteries quickly and safely while avoiding capacity loss and safety risks, a novel electrode design that minimizes cell polarization at a higher current is highly desired. This work presents a dual-layer electrode (DLE) technology via sequential coating of two different anode materials to minimize the overall electrode resistance upon fast charging. Electrochemical impedance spectroscopy and distribution of relaxation times analysis revealed the dynamic evolution of electrode impedances in synthetic graphite (SG) upon a change in the state of charge (SOC), whereas the natural graphite (NG) maintains its original impedance regardless of SOC variation. This disparity dictates the sequence of the NG and SG coating layers within the DLE, considering the temporal SOC gradient developed upon fast charging. Simulation and experimental results suggest that DLE positioning NG and SG on the top (second-layer) and bottom (first-layer), respectively, can effectively reduce the overall resistance at a 4 C-rate (15-min charging), demonstrating two times higher capacity retention (61.0%) over 200 cycles than its counterpart with reversal sequential coating, and is higher than single-layer electrodes using NG or NG/SG binary mixtures. Hence, this study can guide the combinatorial sequence for multi-layer coating of various active materials for a lower-resistivity, thick-electrode design.

Diagnosis of Current Flow Patterns Inside Fault-Simulated Li-Ion Batteries via Non-Invasive, In Operando Magnetic Field Imaging.

With the growing popularity of Li-ion batteries in large-scale applications, building a safer battery has become a common goal of the battery community. Although the small errors inside the cells trigger catastrophic failures, tracing them and distinguishing cell failure modes without knowledge of cell anatomy can be challenging using conventional methods. In this study, a real-time, non-invasive magnetic field imaging (MFI) analysis that can signal the battery current-induced magnetic field and visualize the current flow within Li-ion cells is developed. A high-speed, spatially resolved MFI scan is used to derive the current distribution pattern from cells with different tab positions at a current load. Current maps are collected to determine possible cell failures using fault-simulated batteries that intentionally possess manufacturing faults such as lead-tab connection failures, electrode misalignment, and stacking faults (electrode folding). A modified MFI analysis exploiting the magnetic field interference with the countercurrent-carrying plate enables the direct identification of defect spots where abnormal current flow occurs within the pouch cells.

Correction: Aggregation or phase separation can be induced in highly charged proteins by small charged biomolecules.

Correction for 'Aggregation or phase separation can be induced in highly charged proteins by small charged biomolecules' by Minchae Kang et al., Soft Matter, 2022, 18, 3313-3317, https://doi.org/10.1039/D2SM00384H.

Aggregation or phase separation can be induced in highly charged proteins by small charged biomolecules.

Protein phase separation in biological systems has captured the attention of scientists in the last decade; however, the main mechanism underlying protein phase separation in cells remains unclear. Biologists, physicists, and chemists have all tried to understand this important biological phenomenon, each using their own unique techniques and language. Each subject has its advantages in explaining protein phase separation; however, in this study, we find that the chemical language of molecular structure is the key to explaining the mechanism underlying protein phase separation. Using fluroescence microscopy and molecular dynamics, this study identifies small multivalently charged biomolecules, such as nucleoside triphosphate (negatively charged) and polyamine (positively charged), as important drivers of phase separation of highly charged proteins in cells.

Mitral Valve Adaptation to Isolated Annular Dilation: Insights Into the Mechanism of Atrial Functional Mitral Regurgitation.

OBJECTIVES: This study hypothesized that compensatory mitral leaflet area (MLA) adaptation occurs in patients with persistent atrial fibrillation (AF) without left ventricular (LV) dysfunction but has limitations that augment mitral regurgitation (MR). The study also explored whether asymmetrical annular dilation is matched by relative leaflet enlargement. BACKGROUND: Functional MR occurs in patients with AF and isolated annular dilation, but the relationship of MLA adaptation with annular area (AA) is unknown. METHODS: Three-dimensional echocardiographic images were acquired from 86 patients with quantified MR: 53 with nonvalvular persistent AF (23 MR+ with moderate or greater MR, 30 MR-) without LV dysfunction or dilation and 33 normal controls. Comprehensive 3-dimensional analysis included total diastolic MLA, adaptation ratios of MLA to annular area and MLA to leaflet closure area, and annular and tenting geometry. RESULTS: Total MLA was 22% larger in patients with AF than in controls, thus paralleling the increased AA. However, as AA increased, adaptive indices (MLA/AA ratio and ratio of MLA to closure area) plateaued, becoming lowest in MR+ patients (ratio of MLA to closure area = 1.63 ± 0.17 controls, 1.60 ± 0.11 MR-, 1.32 ± 0.10 MR+; p < 0.001). MR increased as the ratio of MLA to closure area decreased (R2 = 0.68; p < 0.001). The posterior-to-anterior MLA ratio remained constant, whereas the posterior-to-anterior mitral annulus perimeter increased (1.21 ± 0.16 controls, 1.32 ± 0.20 MR-, 1.46 ± 0.19 MR+; p < 0.001). Multivariate MR determinants were annular area, total MLA to closure area, and posterior-to-anterior perimeter ratios. CONCLUSIONS: MLA adaptively increases in AF with isolated annular dilation and normal LV function. This compensatory enlargement becomes insufficient with greater annular dilation, and the leaflets fail to match asymmetrical annular remodeling, thereby increasing MR. These findings can potentially help optimize therapeutic options and motivate basic studies of adaptive growth processes.

Quantitative segmental analysis of myocardial perfusion to differentiate stress cardiomyopathy from acute myocardial infarction: A myocardial contrast echocardiography study.

BACKGROUND: Both stress cardiomyopathy (SCMP) and acute myocardial infarction (AMI) present with similar clinical symptoms and signs, and apical akinesis. HYPOTHESIS: Quantitative segmental analysis of myocardial contrast echocardiography (MCE) helps to differentiate AMI from SCMP. METHODS: Real-time MCE was performed in 33 consecutive patients who presented with an acute symptom/sign and a new apical akinesis on echocardiography. In 18 left ventricular (LV) myocardial segments, a replenishment curve was obtained in each segment to measure peak plateau myocardial contrast intensity (MCI) (A) and the replenishment curve slope (ß). The calibrated MCI was also measured in each segment. RESULTS: Among 33 patients, 22 were diagnosed with SCMP and 11 were diagnosed with AMI according to comprehensive diagnostic criteria. A, ß, Aß, and the calibrated MCI were lower in akinetic than in normokinetic segments in both the SCMP and AMI groups. In the akinetic segments, A, ß, Aß, and the calibrated MCI in SCMP patients were each higher than those in AMI patients. In patient-based analyses, areas under the ROC curves of A, ß, Aß, and the calibrated MCI for diagnosing AMI were 0.769, 0.607, 0.822, and 0.934, respectively. The optimal cutoff values to diagnose AMI were Aß < 3.7 dB/sec (sensitivity 82%, specificity 82%) and a calibrated MCI < -23 dB (sensitivity 91%, specificity 95%). CONCLUSIONS: Although myocardial perfusion is relatively reduced in the akinetic segments of SCMP, a quantitative segmental analysis of myocardial perfusion using MCE helps to discriminate AMI from SCMP.