Li‐rich layered oxide cathodes with conventional transition metal cation and unique oxygen anion redox reactions deliver high capacities in Li‐ion batteries. However, the oxygen redox process causes ...the oxygen release, voltage fading/hysteresis, and sluggish electrochemical kinetics, which undermine the performance of these materials. By combining operando quick‐scanning X‐ray absorption spectroscopy with online gas chromatography, the effect of the local electronic structure is elucidated on the reaction mechanism and electrochemical kinetics of Li‐rich cathodes. The local electronic structure of Li‐rich cathodes varies with the excess Li (i.e., Li2MnO3 phase) and Ni contents. Compared to the Li‐rich cathodes with higher amounts of Li2MnO3 phase (high excess lithium content (HLC) cathode), those with lower Li2MnO3 contents (low excess lithium content (LLC) cathode) exhibit reversible anion redox reactions and suppressed voltage hysteresis. The cation oxidation process of LLC cathode is kinetically slower than that of HLC cathode and the cation oxidation potential is shifted, likely due to the local coordination associated with different Li/O ratios. The obtained insights into the effect of local electronic structure on the reaction mechanism and kinetics provide a better understanding and control of Li‐rich cathodes.
This research reveals the reaction mechanism and electrochemical kinetics of Li‐rich cathodes using in operando quick‐scanning X‐ray absorption spectroscopy. With the control of Li2MnO3 domain, cation migration and voltage decay were suppressed. The electrochemical stability and kinetics of tradition metal (TM) redox can be tuned by modifying the local coordination structure of Li‐rich cathode.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
TiO2 is an ideal photocatalyst candidate except for its large bandgap and fast charge recombination. A novel laminated junction composed of defect‐controlled and sulfur‐doped TiO2 with carbon ...substrate (LDC‐S‐TiO2/C) is synthesized using the 2D transition metal carbides (MXenes) as a template to enhance light absorption and improve charge separation. The prepared LDC‐S‐TiO2/C catalyst delivers a high photocatalytic H2 evolution rate of 333 µmol g−1 h−1 with a high apparent quantum yield of 7.36% at 400 nm and it is also active even at 600 nm, resulting into a 48 time activity compared with L‐TiO2/C under visible light irradiation. Further theoretical modeling calculation indicates that such novel approach also reduces activation energy of hydrogen production apart from broadening the absorption wavelength, facilitating charge separation, and creating a large surface area substrate. This synergic effect can also be applied to other photocatalysts' modification. The study provides a novel approach for synthesis defective metal oxides based hybrids and broaden the applications of MXene family.
A laminated hybrid junction of sulfur‐doped TiO2 and carbon substrate via a sulfur impregnation into Ti3C2 MXenes and the subsequent oxidation processes is demonstrated. The defects design on carbon is helpful for the enhancement of photocatalytic activity and a novel method is demonstrated to synthesize highly active photocatalysts for solar energy conversion.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Emerging evidence indicates that microRNAs (miRNAs) have important roles in regulating osteogenic differentiation and bone formation. Thus far, no study has established the pathophysiological role ...for miRNAs identified in human osteoporotic bone specimens. Here we found that elevated miR-214 levels correlated with a lower degree of bone formation in bone specimens from aged patients with fractures. We also found that osteoblast-specific manipulation of miR-214 levels by miR-214 antagomir treatment in miR-214 transgenic, ovariectomized, or hindlimb-unloaded mice revealed an inhibitory role of miR-214 in regulating bone formation. Further, in vitro osteoblast activity and matrix mineralization were promoted by antagomir-214 and decreased by agomir-214, and miR-214 directly targeted ATF4 to inhibit osteoblast activity. These data suggest that miR-214 has a crucial role in suppressing bone formation and that miR-214 inhibition in osteoblasts may be a potential anabolic strategy for ameliorating osteoporosis.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Antibiotic resistance is a growing problem, especially in the treating of life-threatening diseases like sepsis. One way to address such an issue is with the use of antimicrobial peptides, which can ...kill many types of bacteria by disrupting cellular targets (such as membranes) through electrostatic interaction. In this report, cysteine-derived cationic dipeptides lysine–cysteine (KC), arginine–cysteine (RC) and histidine–cysteine (HC) were used to evaluate antibacterial activity against Gram-negative and positive bacteria. The dipeptides exhibited bacterial membrane rupture capabilities under SEM observation after treatment with IC
50
conditions, as well as low cytotoxicity and hemolytic activity toward normal cell lines and human red blood cells (RBCs) at IC
50
. Furthermore, the dipeptides significantly ameliorated
Enterohaemorrhagic E. coli (EHEC)
-induced lethality in
Caenorhabditis elegans
in a dose-dependent manner. These cysteine-derived cationic dipeptides may provide a novel alternative therapy in combating bacterial infection.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
In coastal areas of southeastern China, multiple flood drivers such as river flow, precipitation and coastal water level can lead to compound flooding which is often much greater than flooding ...simulated by one flood driver in isolation. Bivariate probability distributions accounting for compound flooding from river discharge and sea level were constructed based on MvCAT (Multivariate Copula Analysis Toolbox) combined with goodness of fit tests in 15 coastal-estuarine regions of Southeastern China. Flood typing-based bivariate probability distributions considering multiple flood-generating mechanisms were also built. Our results indicated that the performance of flood typing-based bivariate distribution was not significantly better than the bivariate probability distribution in coastal-estuarine regions based on the Mann–Whitney U test; the compounding effects of river discharge and sea level had limited impact on bivariate return periods, but had greater impact on coastal flooding risk in terms of design values. Ignoring compounding effects of river discharge and sea level leads to significant underestimation of design values. The results suggest that the compounding effect of river discharge and sea level should be considered when calculating design values in coastal flood risk assessment.
The magnetic compensation and magnetostriction properties in Fe‐doped CoCr2O4 samples have been investigated. Structural and magnetic measurements imply that the doped Fe3+ ions initially occupy the ...B1 (Cr) sites when x < 0.1, and then mainly take the A (Co) sites. This behaviour results in a role conversion of magnetic contributors and a composition compensation between two competitively magnetic sublattices at x = 0.1. Temperature‐dependent compensation has also been found in the samples with x = 0.1–0.22, with the compensation temperature in the range of 40–104 K. The Fe3+ doping also modulates the exchange interaction of the system and prevents the formation of long‐range conical order of spins. The magnetoelectric transition temperature at 23 K in CoCr2O4 is shifted to lower temperature by increasing the dopants. The magnetostriction effect in this system has been observed for the first time. The strain has a maximum value of about 280 ppm at x = 0.4. The magnetostriction is consistent with the behaviour of the two magnetic compensations.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Purpose: The purpose of this study was to determine whether different initiation of exercise training (ET) produces different effect sizes for left ventricular (LV) remodeling and cardiopulmonary ...rehabilitation in patients with LV dysfunction after myocardial infarction (MI). Method: Trials evaluating ET outcomes identified by searches in OVID MEDLINE, EMBASE, PubMed and WEB OF SCIENCE were used. Meta-analysis was conducted with the use of the software STATA 11.0. The results were expressed as the standardized mean difference (SMD), with corresponding 95% CI and p value. Results: The largest changes in LV remodeling and cardiopulmonary capacity rehabilitation were obtained when programs began the acute phase after MI. With the healing of MI, the beneficial effects of ET on LV ejection fraction (LVEF), LV end-systolic diameter (LVDs) and peak VO
2
were gradually weakened even worse. The incidence of major adverse cardiac events was not significantly increased in acute phase post-MI. Sensitivity analyses show that ET still had significant effect in reducing LVDs and increasing peak VO
2
, while ET no longer had statistical effect in increasing LVEF but showed favorable trends when the same research institution's works were excluded. Conclusions: ET has favorable effects on LV remodeling and cardiopulmonary rehabilitation in LV dysfunction post-MI patients. The greatest benefits are obtained when ET starts at the acute phase following MI.
Implications for Rehabilitation
Early exercise training is safe and feasible in acute and healing phase after myocardial infarction.
Early exercise training could attenuate LV remodeling and improve cardiopulmonary capacity in patients with myocardial infarction after hospital discharge (around one week post-MI).
Exercise training has favorable effects on LV remodeling and cardiopulmonary capacity rehabilitation. Exercise training should be treated to have the same roles with drugs in secondary prevention of myocardial infarction.
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IJS, NUK, UL, UM, UPUK, VSZLJ
Abstract
In the archetypal lithium-rich cathode compound Li
1.2
Ni
0.13
Co
0.13
Mn
0.54
O
2
, a major part of the capacity is contributed from the anionic (O
2−/−
) reversible redox couple and is ...accompanied by the transition metal ions migration with a detrimental voltage fade. A better understanding of these mutual interactions demands for a new model that helps to unfold the occurrences of voltage fade in lithium-rich system. Here we present an alternative approach, a cationic reaction dominated lithium-rich material Li
1.083
Ni
0.333
Co
0.083
Mn
0.5
O
2
, with reduced lithium content to modify the initial band structure, hence ~80% and ~20% of capacity are contributed by cationic and anionic redox couples, individually. A 400 cycle test with 85% capacity retention depicts the capacity loss mainly arises from the metal ions dissolution. The voltage fade usually from Mn
4+
/Mn
3+
and/or O
n−
/O
2−
reduction at around 2.5/3.0 V seen in the typical lithium-rich materials is completely eliminated in the cationic dominated cathode material.
We fabricate a microscale electromechanical system, in which a suspended superconducting membrane, treated as a mechanical oscillator, capacitively couples to a superconducting microwave resonator. ...As the microwave driving power increases, nonmonotonic dependence of the resonance frequency of the mechanical oscillator on the driving power has been observed. We also demonstrate the optical switching of the resonance frequency of the mechanical oscillator. Theoretical models for qualitative understanding of our experimental observations are presented. Our experiment may pave the way for the application of a mechanical oscillator with its resonance frequency controlled by the electromagnetic and/or optical fields, such as a microwave-optical interface and a controllable element in a superqubit-mechanical oscillator hybrid system.
Phase-sensitive surface plasmon resonance biosensors are known for their high sensitivity. One of the technology bottle-necks of such sensors is that the phase sensorgram, when measured at fixed ...angle set-up, can lead to low reproducibility as the signal conveys multiple data. Leveraging the sensitivity, while securing satisfying reproducibility, is therefore is an underdiscussed key issue. One potential solution is to map the phase sensorgram into refractive index unit by the use of sensor calibration data, via a simple non-linear fit. However, basic fitting functions poorly portray the asymmetric phase curve. On the other hand, multi-layer reflectivity calculation based on the Fresnel coefficient can be employed for a precise mapping function. This numerical approach however lacks the explicit mathematical formulation to be used in an optimization process. To this end, we aim to provide a first methodology for the issue, where mapping functions are constructed from Bayesian optimized multi-layer model of the experimental data. The challenge of using multi-layer model as optimization trial function is addressed by meta-modeling via segmented polynomial approximation. A visualization approach is proposed for assessment of the goodness-of-the-fit on the optimized model. Using metastatic cancer exosome sensing, we demonstrate how the present work paves the way toward better plasmonic sensors.
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