The high gravimetric energy density and environmental benefits place hydrogen as a promising alternative to the widely used fossil fuels, which is however impeded by the lack of safe, energy-saving ...and cost-effective H
2
storage systems. The use of solid adsorbents as candidate materials offers a less energy-intensive way of storing hydrogen. The exceptional diversity and tunability of the chemical composition, topological structure, and surface chemistry together with large surface area position porous metal-organic frameworks as promising hydrogen storage material candidates. In this review, we first introduce several classes of important metal-organic frameworks for hydrogen storage, and then highlight the progress associated with the key challenges to be addressed, including the improvement of hydrogen-framework interaction required for enhancing room-temperature hydrogen storage capacities, and the optimization/balance of both gravimetric and volumetric storage/working capacities. In particular, the strategies used to tune and enhance hydrogen binding energies have been comprehensively reviewed. Future development prospects and related challenges of using porous metal-organic frameworks as hydrogen storage materials are also outlined. This feature review provides a wide perspective and insightful thoughts and suggestions for hydrogen storage using metal-organic frameworks, and promotes the further development of hydrogen storage materials to realize a hydrogen economy.
This article reviews the recent progress in the use of metal-organic frameworks as solid absorbents for hydrogen storage, and their current challenges and future prospects.
The combination of alkali metal electrodes and solid-state electrolytes is considered a promising strategy to develop high-energy rechargeable batteries. However, the practical applications of these ...two components are hindered by the large interfacial resistance and growth of detrimental alkali metal depositions (e.g., dendrites) during cycling originated by the unsatisfactory electrode/solid electrolyte contact. To tackle these issues, we propose a room temperature ultrasound solid welding strategy to improve the contact between Na metal and Na
Zr
Si
PO
(NZSP) inorganic solid electrolyte. Symmetrical Na|NZSP | Na cells assembled via ultrasonic welding show stable Na plating/stripping behavior at a current density of 0.2 mA cm
and a higher critical current density (i.e., 0.6 mA cm
) and lower interfacial impedance than the symmetric cells assembled without the ultrasonic welding strategy. The beneficial effect of the ultrasound welding is also demonstrated in Na|NZSP | Na
V
(PO
)
full coin cell configuration where 900 cycles at 0.1 mA cm
with a capacity retention of almost 90% can be achieved at room temperature.
Wind energy, as a kind of environmentally friendly renewable energy, has attracted a lot of attention in recent decades. However, the security and stability of the power system is potentially ...affected by large-scale wind power grid due to the randomness and intermittence of wind speed. Therefore, accurate wind speed prediction is conductive to power system operation. A hybrid wind speed prediction model based on Improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (ICEEMDAN), Multiscale Fuzzy Entropy (MFE), Long short-term memory (LSTM) and INFORMER is proposed in this paper. Firstly, the wind speed data are decomposed into multiple intrinsic mode functions (IMFs) by ICEEMDAN. Then, the MFE values of each mode are calculated, and the modes with similar MFE values are aggregated to obtain new subsequences. Finally, each subsequence is predicted by informer and LSTM, each sequence selects the one with better performance than the two predictors, and the prediction results of each subsequence are superimposed to obtain the final prediction results. The proposed hybrid model is also compared with other seven related models based on four evaluation metrics under different prediction periods to verify its validity and applicability. The experimental results indicate that the proposed hybrid model based on ICEEMDAN, MFE, LSTM and INFORMER exhibits higher accuracy and greater applicability.
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Electrical explosion of a wire (EEW) has been investigated for more than ten years at
Tsinghua University, and the main results are reviewed in this paper. Based on EEW in
vacuum, an X-pinch was used ...as an x-ray source for phase-contrast imaging of small insects
such as mosquitoes and ants in which it was possible to observe clearly their detailed
internal structures, which can never be seen with conventional x-ray radiography.
Electrical explosion of a wire array (EEWA) in vacuum is the initial stage in the
formation of a wire-array Z-pinch. The evolution of EEWA was observed with x-ray
backlighting using two X-pinches as x-ray sources. It was found that each wire in an EEWA
exhibits a core–corona structure instead of forming a fully vaporized metallic vapor. This
structure is detrimental to the plasma implosion of a Z-pinch. By inserting an insulator
as a flashover switch into the cathode, formation of a core–corona structure was
suppressed and core-free EEWA was realized. EEW in gases was used for nanopowder
production. Three parameters (vaporization rate, gas pressure, and energy deposited in the
exploding plasma) were found to influence the nanoparticle size. EEW in water was used for
shock-wave generation. The shock wave generated by melting could be recorded with a
piezoelectric gauge only in underheat EEW. For EEW with a given stored energy but
different energy-storage capacitor banks, the small capacitor bank produced a rapidly
rising current that deposited more energy into the wire and generated a stronger shock
wave.
Structure of nucleosome-bound human BAF complex He, Shuang; Wu, Zihan; Tian, Yuan ...
Science (American Association for the Advancement of Science),
02/2020, Volume:
367, Issue:
6480
Journal Article
Peer reviewed
Mammalian SWI/SNF family chromatin remodelers, BRG1/BRM-associated factor (BAF) and polybromo-associated BAF (PBAF), regulate chromatin structure and transcription, and their mutations are linked to ...cancers. The 3.7-angstrom-resolution cryo-electron microscopy structure of human BAF bound to the nucleosome reveals that the nucleosome is sandwiched by the base and the adenosine triphosphatase (ATPase) modules, which are bridged by the actin-related protein (ARP) module. The ATPase motor is positioned proximal to nucleosomal DNA and, upon ATP hydrolysis, engages with and pumps DNA along the nucleosome. The C-terminal α helix of SMARCB1, enriched in positively charged residues frequently mutated in cancers, mediates interactions with an acidic patch of the nucleosome. AT-rich interactive domain-containing protein 1A (ARID1A) and the SWI/SNF complex subunit SMARCC serve as a structural core and scaffold in the base module organization, respectively. Our study provides structural insights into subunit organization and nucleosome recognition of human BAF complex.
Vegetation plays an essential role in improving urban environments and enhancing the physical and mental health of residents. However, rapid urbanization has exerted complicated influence on ...vegetation conditions, which remain poorly understood. To assess the impacts of urbanization on the vegetation structure and function in the urban area, we quantified the changes in impervious surface area (ISA) and assessed the impacts of urbanization on vegetation greenness (enhanced vegetation index (EVI)), and gross primary production (GPP) in megacity Shanghai during 2000–2016. The results show that 38.0% and 28.0% decreasing trends of EVI and GPP occurred in peri-urban and rural areas due to land use and land cover conversion, whereas 2.8% and 4.6% increasing trends of EVI and GPP occurred in the central city during 2000–2016 in Shanghai. In addition, the enhancement of EVI and GPP owing to the indirect impact of urbanization increased as the impervious surface coverage (ISC) gradient rose and peaked when the ISC reached ~0.8, which compensated for vegetation loss by 24.6% and 17.0%, respectively. The compensation was more stable and significant in peri-urban areas than urban and rural areas. This study provides detailed data and insights on the impacts of urbanization on vegetation, which may help stakeholders to make better management plans for urban vegetation.
•We characterized the pattern of urbanization in Shanghai during 2000–2016.•We explored the spatial-temporal relationships between vegetation and urbanization.•Land conversion caused vegetation and carbon loss in peri-urban and rural areas.•The enhancement of vegetation peaked at the impervious surface coverage of 0.8.•The enhancement could compensate for vegetation loss by around 20%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The aim of this systematic review and meta-analysis was to investigate the pooled prevalence of cognitive frailty among community-dwelling older adults and provide evidence-based support for ...policy-makers planning health and social care policies.
A systematic review and meta-analysis.
PubMed, Web of Science, Embase and the Cochrane Library were systematically searched from their inception to December 10, 2020. Descriptive studies (cross-sectional studies or population-based longitudinal studies) and cohort studies were available. Participants were community-dwelling older adults aged 60 years and above. Two researchers independently screened the literature, extracted the data and evaluated the quality of the included studies. All statistical analyses were conducted using Stata 15.0.
We screened 2815 records, among which 24 studies met the inclusion criteria and were included in the review. The pooled prevalence of cognitive frailty was 9% (95% CI: 8%-11%, I2 = 99.3%). The results of the subgroup analysis showed that the pooled prevalence of cognitive frailty was 11% (95% CI: 9%-14%) in men and 15% (95% CI: 11%-19%) in women. The pooled prevalence of cognitive frailty based on the descriptive studies and cohort studies was 7% (95% CI: 5%-9%) and 17% (95% CI: 11%-22%), respectively. The pooled estimates of cognitive frailty prevalence were 6% (95% CI: 4%-8%) from 2012 to 2017 and 11% (95% CI: 9%-14%) from 2018 to 2020.
This systematic review analyzed the available literature and revealed that the pooled prevalence of cognitive frailty among community-dwelling older adults was 9%. The stratified analysis showed that the prevalence of cognitive frailty was higher in older women. In addition, the prevalence has increased in recent years, which has important implications for adapting health and social care systems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Carbonate sediments transported into the mantle at subduction zone settings account for the majority of the carbon flux into the Earth's interior and are thus critical to the deep carbon cycle. ...Understanding carbon storage volumes in the deep earth requires knowledge of the degree to which carbonate sediments are stored in the arc lithosphere or descend to the deep mantle. Here, we use petrological‐thermomechanical modeling to indicate that solid‐state diapirs dominate the removal of carbon from subducting plates, which may be the principal carbon‐release mechanism for the Cyclades (Greece) and Costa Rican forearcs. We find that forearc diapirs remove up to ∼80% of subducting carbon and develop diagonally upward, resulting in massive carbon storage in the subarc lithosphere. Outgassing from the carbon storage may cause high carbon outputs and explain volcanic gas with high δ13C at some subduction zones, affecting atmospheric CO2 concentration.
Plain Language Summary
Whereas many concepted models for the fate of subducting carbon, mainly from the sedimentary carbonates, have been proposed, it remains unclear to which extend these ideas are consistent with carbon balance between the shallow and deep reservoirs. The dynamic processes by which carbon release from subducting sediments and the transit into the shallow reservoirs above subarc depths remain largely unanswered. In this study, we account for metamorphic decarbonation and coupled with thermomechanical models, to investigate the dynamics of subducting sediments and associated carbon flux. Results show that solid‐state diapirs formed in the forearc remove substantial amounts of sedimentary carbon, which are much more than that via subarc diapirs and metamorphic reactions, and indicate that they dominate the carbon release from subducting sediments. The massive carbon stored in the overlying lithosphere reservoir is formed via the diagonal transport of forearc diapirs provided that a thick sediment, a young oceanic plate, and slow convergence are present. We argue that the remobilization of sedimentary carbon in the subarc lithosphere can provide an efficient mechanism for the abnormally high decarbonation efficiency of the volcanism in subduction zones, therefore regulating the Earth's climate.
Key Points
We conduct 2D petrological‐thermomechanical models to explore the sediment subduction and recycling in subduction zones
Young oceanic plates, slow convergence rates, and thick sediments promote forearc diapirs and cause high decarbonation efficiency
Forearc diapirs dominate removal of carbon from the subducting plate and reduce the proportion of the carbon released at subarc depths
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Cell membranes are flexible and often undergo large-scale morphological changes during processes like mitosis, protrusion and retraction, or vesicle fusion. Mathematical modeling of cell membranes ...depends on a representation of the free-form surface by discrete meshes. During morphological changes, these meshes must be adjusted under the minimization of the total free energy. Current methodology for meshing is limited in one of two ways: 1) Free energy-dependent methods have no restriction on the mesh geometry. The resulting irregular meshes cause artifacts in follow-up models of morphodynamics. 2) Geometry-dependent methods maintain mesh quality but violate the physics of free energy minimization. To fill this gap, we regulate mesh geometries via a free-energy-determined remeshing process: adding and removing mesh elements upon morphological changes based on barrier crossings in a double-barrier potential between neighboring vertices in the meshes. We test the method's robustness by reproducing the morphodynamics of red blood cells and vesicle fusions; and we demonstrate the method's adaptability by simulating the formation of filopodia, lamellipodia and invaginations. Finally, we use the method to study a mechanical decoupling effect of two connected membrane tethers that has been recently observed experimentally, but has not been mechanistically explained in the context of a complete membrane surface. We propose a biophysical model that strengthens the decoupling effect and broadens the original interpretation of the experiment. The method is developed in C/Matlab and distributed via https://github.com/DanuserLab/biophysicsModels.
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