Impossible voltage plateau regulation for the cathode materials with fixed active elemental center is a pressing issue hindering the development of Na‐superionic‐conductor (NASICON)‐type ...Na3V2(PO4)2F3 (NVPF) cathodes in sodium‐ion batteries (SIBs). Herein, a high‐entropy substitution strategy, to alter the detailed crystal structure of NVPF without changing the central active V atom, is pioneeringly utilized, achieving simultaneous electronic conductivity enhancement and diffusion barrier reduction for Na+, according to theoretical calculations. The as‐prepared carbon‐free high‐entropy Na3V1.9(Ca,Mg,Al,Cr,Mn)0.1(PO4)2F3 (HE‐NVPF) cathode can deliver higher mean voltage of 3.81 V and more advantageous energy density up to 445.5 Wh kg−1, which is attributed by the diverse transition‐metal elemental substitution in high‐entropy crystalline. More importantly, high‐entropy introduction can help realize disordered rearrangement of Na+ at Na(2) active sites, thereby to refrain from unfavorable discharging behaviors at low‐voltage region, further lifting up the mean working voltage to realize a full Na‐ion storage at the high voltage plateau. Coupling with a hard carbon (HC) anode, HE‐NVPF//HC SIB full cells can deliver high specific energy density of 326.8 Wh kg−1 at 5 C with the power density of 2178.9 W kg−1. This route means the unlikely potential regulation in NASICON‐type crystal with unchangeable active center becomes possible, inspiring new ideas on elevating the mean working voltage for SIB cathodes.
A high‐entropy effect is delicately introduced into fluorophosphate cathode for sodium‐ion batteries by in situ partial substitution of active V central atom, preparing a high‐entropy carbon‐free Na3V1.9(Ca,Mg,Al,Cr,Mn)0.1(PO4)2F3 cathode, suppressing the occurrence of detrimental phase transition process in the low‐voltage region, and further lifting up the mean working voltage of pristine Na3V2(PO4)2F3, enhancing sodium storage behavior, rate capability, and cycle performance.
El Niño–Southern Oscillation (ENSO) is the dominant mode of variability in the coupled ocean-atmospheric system. Future projections of ENSO change under global warming are highly uncertain among ...models. In this study, the effect of internal variability on ENSO amplitude change in future climate projections is investigated based on a 40-member ensemble from the Community Earth System Model Large Ensemble (CESM-LE) project. A large uncertainty is identified among ensemble members due to internal variability. The inter-member diversity is associated with a zonal dipole pattern of sea surface temperature (SST) change in the mean along the equator, which is similar to the second empirical orthogonal function (EOF) mode of tropical Pacific decadal variability (TPDV) in the unforced control simulation. The uncertainty in CESM-LE is comparable in magnitude to that among models of the Coupled Model Intercomparison Project phase 5 (CMIP5), suggesting the contribution of internal variability to the intermodel uncertainty in ENSO amplitude change. However, the causations between changes in ENSO amplitude and the mean state are distinct between CESM-LE and CMIP5 ensemble. The CESM-LE results indicate that a large ensemble of ~15 members is needed to separate the relative contributions to ENSO amplitude change over the twenty-first century between forced response and internal variability.
The skin, which serves as the first barrier of the human body, is particularly susceptible to exogenous injuries. Skin wounds, including acute burns and chronic non-healing ulcers, are commonly ...observed in clinics. Healing of skin wounds is a complex process, consisting of infiltration of inflammatory cells, cellular proliferation, and tissue remodeling phases, which restore the integrity and functions of the skin. Epithelialization is involved in wound healing through re-establishing an intact keratinocyte layer. Epidermal stem cells are indispensable for epithelialization, and they are regulated by multiple proinflammatory cytokines or growth factors. In this review, we summarize recent advances in the effect of these cytokines on migration, proliferation, and differentiation processes of epidermal stem cells. We also introduce promising therapeutic strategies targeting epidermal stem cells or related proinflammatory cytokines for patients with skin wounds.
In the strong deflection gravitational lensing, given the fact that a black-bounce, traversable wormhole is indistinguishable from a Schwarzschild black hole and is loosely tested by the Event ...Horizon Telescope, we intensively study its signatures of weak deflection gravitational lensing in light of the tremendous progress made by the new generation of the near-infrared interferometer GRAVITY. After obtaining its observables, which are the positions, magnitudes of brightness, centroid, and differential time delay between the lensed images, we investigate three astrophysical scenarios: an orbiting star lensed by the Galactic Center Sgr A*, a microlensed star in the Galactic bulge, and microlensing by a nearby lens. We find that the measurements of the observables of Sgr A* provide a promising way to test the black-bounce, traversable wormhole spacetime. GRAVITY can resolve the angular separation, the angular difference, and the time delay between the two lensed images by Sgr A*, and it can marginally detect their deviations from those of the Schwarzschild black hole. The brightness difference between the images and its deviation might be measured by a dedicated space telescope. In the near future, we expect that such a spacetime would be more robustly tested with the weak deflection gravitational lensing by further improved and upgraded GRAVITY+.
This review summarizes the latest synthesis methods, characterization and corresponding applications of MOF-74 and its derivatives in recent years. Metal–organic frameworks (MOFs) are nanomaterials ...with many attractive advantages, such as good stability, large specific surface area and large apertures, which make them receive considerable attention. Among them, MOF-74 is a particularly outstanding one attribute to its excellent CO2 adsorption capacity. MOF-74 can be synthesized directly from a metal oxide and without bulk solvent, which not only saves a lot of time and money, but also is more ecological. The mesopores in MOF-74 can be adjusted to as large as 15 nm stably at room temperature. And characterization results show MOF-74 possesses good hydrolysis stability, highly stable structure, gas adsorption capacity, catalytic activity and so on. In addition, multifarious synthetic materials with additional functionality can be obtained by properly combining MOF-74 with other components. Therefore, MOF-74 has great potential and has aroused great enthusiasm for research in many aspects, such as gas adsorption, separation, and catalysis and so on.
The biggest highlight of MOF-74 is its excellent carbon dioxide adsorption properties, especially Mg-MOF-74, which is attractive in realizing CO2 high efficiency and energy saving. The adsorption behavior and mechanism were summarized in detail. In addition, we also introduced the performance of MOF-74 in other gas adsorption, such as H2, O2. New synthetic methods, like directly from a metal oxide, provide more ideas and richer materials for the further research of MOF-74. In addition, the good stability of MOF-74 is of great significance for its wide application. And different kinds of derivatives have great application value in various aspects such as gas adsorption, separation, catalysis, molecular probes, and drug transportation and so on. Display omitted
•New MOF-74 synthesis methods are introduced, which help reduce cost and protect environment.•This review describes the good properties of MOF-74, especially its good stability.•The adsorption behaviors of MOF-74 on various common gases are summarized.•The mechanisms of various reactions of MOF-74 are described.•Many analogues of MOF-74 are introduced, which play an important role in future research.
A major progress in deep multilayer neural networks (DNNs) is the invention of various unsupervised pretraining methods to initialize network parameters which lead to good prediction accuracy. This ...paper presents the sparseness analysis on the hidden unit in the pretraining process. In particular, we use the L1-norm to measure sparseness and provide some sufficient conditions for that pretraining leads to sparseness with respect to the popular pretraining models- such as denoising autoencoders (DAEs) and restricted Boltzmann machines (RBMs). Our experimental results demonstrate that when the sufficient conditions are satisfied, the pretraining models lead to sparseness. Our experiments also reveal that when using the sigmoid activation functions, pretraining plays an important sparseness role in DNNs with sigmoid (Dsigm), and when using the rectifier linear unit (ReLU) activation functions, pretraining becomes less effective for DNNs with ReLU (Drelu). Luckily, Drelu can reach a higher recognition accuracy than DNNs with pretraining (DAEs and RBMs), as it can capture the main benefit (such as sparseness-encouraging) of pretraining in Dsigm. However, ReLU is not adapted to the different firing rates in biological neurons, because the firing rate actually changes along with the varying membrane resistances. To address this problem, we further propose a family of rectifier piecewise linear units (RePLUs) to fit the different firing rates. The experimental results show that the performance of RePLU is better than ReLU, and is comparable with those with some pretraining techniques, such as RBMs and DAEs.
One of the most effective ways to cope with the problems of global warming and the energy shortage crisis is to develop renewable and clean energy sources. To achieve a carbon‐neutral energy cycle, ...advanced carbon sequestration technologies are urgently needed, but because CO2 is a thermodynamically stable molecule with the highest carbon valence state of +4, this process faces many challenges. In recent years, electrochemical CO2 reduction has become a promising approach to fix and convert CO2 into high‐value‐added fuels and chemical feedstock. However, the large‐scale commercial use of electrochemical CO2 reduction systems is hindered by poor electrocatalyst activity, large overpotential, low energy conversion efficiency, and product selectivity in reducing CO2. Therefore, there is an urgent need to rationally design highly efficient, stable, and scalable electrocatalysts to alleviate these problems. This minireview also aims to classify heterogeneous nanostructured electrocatalysts for the CO2 reduction reaction (CDRR).
Change for the better: Recent research on 0D, 1D, 2D, and multi‐component nanostructured materials for heterogeneous electrocatalytic CO2 conversion is summarized and discussed. The challenges and development prospects of nanostructured materials for CO2 conversion are also presented.
Kir4.1 in the distal convoluted tubule plays a key role in sensing plasma potassium and in modulating the thiazide-sensitive sodium-chloride cotransporter (NCC). Here we tested whether dietary ...potassium intake modulates Kir4.1 and whether this is essential for mediating the effect of potassium diet on NCC. High potassium intake inhibited the basolateral 40 pS potassium channel (a Kir4.1/5.1 heterotetramer) in the distal convoluted tubule, decreased basolateral potassium conductance, and depolarized the distal convoluted tubule membrane in Kcnj10flox/flox mice, herein referred to as control mice. In contrast, low potassium intake activated Kir4.1, increased potassium currents, and hyperpolarized the distal convoluted tubule membrane. These effects of dietary potassium intake on the basolateral potassium conductance and membrane potential in the distal convoluted tubule were completely absent in inducible kidney-specific Kir4.1 knockout mice. Furthermore, high potassium intake decreased, whereas low potassium intake increased the abundance of NCC expression only in the control but not in kidney-specific Kir4.1 knockout mice. Renal clearance studies demonstrated that low potassium augmented, while high potassium diminished, hydrochlorothiazide-induced natriuresis in control mice. Disruption of Kir4.1 significantly increased basal urinary sodium excretion but it abolished the natriuretic effect of hydrochlorothiazide. Finally, hypokalemia and metabolic alkalosis in kidney-specific Kir4.1 knockout mice were exacerbated by potassium restriction and only partially corrected by a high-potassium diet. Thus, Kir4.1 plays an essential role in mediating the effect of dietary potassium intake on NCC activity and potassium homeostasis.
Developing cost-effective and stable Pt-free electrocatalysts for the oxygen reduction reaction (ORR) is now the key issue for the large-scale application of zinc-air batteries. Here, we present a ...simple charge modulation strategy to synthesize Co
2+
-activated spinel CoMn
2
O
4
supported self-catalysis derived nitrogen-doped carbon nanotubes (CoMn
2
O
4
/NCNTs@Ni). Associated with the formation of high valence Mn
3.4+
over the octahedral site of CoMn
2
O
4
, the corresponding oxygen binding energy can be effectively tuned to greatly enhance the activity of ORR, further revealed by the density functional theory calculations. Benefiting from the highly conductive CoMn
2
O
4
-NCNTs-Ni electron transport channels and high valence Mn
3.4+
, the CoMn
2
O
4
/NCNTs@Ni catalyst exhibits excellent oxygen electrocatalytic activity (the limiting-current density was 5.51 mA cm
−2
) and stability (the current density remained at 86.80% within 24 h), with much lower ORR overpotentials than Mn
3
O
4
/NCNTs@Ni (the limiting-current density was 5.35 mA cm
−2
and the current density remained at 71.63% within 13 h). The as-obtained CoMn
2
O
4
/NCNTs@Ni as a cathode can further assemble a zinc-air battery, which delivers an open-circuit potential of 1.46 V, even close to that of Pt/C (1.50 V), and excellent stability (charge-discharge stably for 238 h). This charge modulation strategy provides a new way to design and explore highly active, durable, and cost-effective catalysts for renewable energy conversion and storage.
The optimized CoMn
2
O
4
/NCNTs@Ni with high valence Mn
3.4+
as the catalytic site center, combined with the spinel-NCNTs-Ni electron transport channels jointly promote the electrocatalytic activity and successfully applied in zinc-air battery.
El Niño–Southern Oscillation (ENSO) induces climate anomalies around the globe. Atmospheric general circulation model simulations are used to investigate how ENSO-induced teleconnection patterns ...during boreal winter might change in response to global warming in the Pacific–North American sector. As models disagree on changes in the amplitude and spatial pattern of ENSO in response to global warming, for simplicity the same sea surface temperature (SST) pattern of ENSO is prescribed before and after the climate warming. In a warmer climate, precipitation anomalies intensify and move eastward over the equatorial Pacific during El Niño because the enhanced mean SST warming reduces the barrier to deep convection in the eastern basin. Associated with the eastward shift of tropical convective anomalies, the ENSO-forced Pacific–North American (PNA) teleconnection pattern moves eastward and intensifies under the climate warming. By contrast, the PNA mode of atmospheric internal variability remains largely unchanged in pattern, suggesting the importance of tropical convection in shifting atmospheric teleconnections. As the ENSO-induced PNA pattern shifts eastward, rainfall anomalies are expected to intensify on the west coast of North America, and the El Niño–induced surface warming to expand eastward and occupy all of northern North America. The spatial pattern of the mean SST warming affects changes in ENSO teleconnections. The teleconnection changes are larger with patterned mean warming than in an idealized case where the spatially uniform warming is prescribed in the mean state. The results herein suggest that the eastward-shifted PNA pattern is a robust change to be expected in the future, independent of the uncertainty in changes of ENSO itself.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
PDF
