Search

Tropical overshooting deep convections (ODCs) play a vital role in vertical transport of boundary layer pollutants, especially short‐lived species, to upper troposphere and lower stratosphere, with important implications for stratospheric ozone and climate. We use simulations from a global cloud‐system resolving model, Nonhydrostatic Icosahedral Atmosphere Model (NICAM), to study ODC changes from historical period to the end of the 21st century. NICAM well reproduces Tropical Rainfall Measuring Mission‐satellite observed ODC spatiotemporal patterns. The future occurrences of ODCs with cloud top height above 15.5, 16.9, and 18.4 km scaled by the global temperature increase will increase by 7%/K, 27%/K, and 90%/K, respectively, over ocean where the atmosphere is becoming warmer and wetter. The corresponding changes are −1%/K, 10%/K, and 37%/K over land where the atmosphere will become hotter but drier. Relative to tropical cold point tropopause height, ODCs will only change by 3%/K, with 6%/K over the ocean but −3%/K on land. Plain Language Summary: Tropical overshooting deep convection (ODC) plays an important role in transporting short‐lived chemical species rapidly from troposphere to stratosphere. This study shows that the simulations from a global cloud‐system resolving model, Nonhydrostatic Icosahedral Atmosphere Model (NICAM), can well capture observed spatiotemporal variations of tropical ODCs. The NICAM simulations predict that by the end of the 21st century (2075–2104) versus the historical period (1979–2008) with a global‐mean surface air temperature increase of 2.67 K, ODC occurrences with cloud tops reaching above 15.5, 16.9, and 18.4 km will increase by 14%, 59%, and 189%, respectively. Thus ODCs with higher cloud tops increase by a larger fraction than ODCs with lower cloud tops. The corresponding changes in ODC occurrences over the future warmer (hotter) and wetter (drier) oceanic (terrestrial) environments will be 20% (−2%), 72% (27%), and 240% (98%). Thus ODCs over ocean generally increase at a faster rate than over land. With tropical cold point tropopause height as a reference level, which will increase from 17.2 to 18.1 km, ODCs will increase by only 8% over the tropics, with 15% over ocean but decrease by −8% over land. Key Points: The Nonhydrostatic Icosahedral Atmosphere Model well reproduces observed spatiotemporal distributions of tropical overshooting deep convections (ODCs)Tropical ODC increases with global temperature on ocean (land) by 7%/K (−1%/K) for ODCs above 15.5 km, 27%/K (10%/K) above 16.9 km, and 90%/K (37%/K) above 18.4 kmResponse of tropical ODCs that penetrate the tropical cold point tropopause height to global warming is 3%/K, with 6%/K over the ocean and −3%/K on land [ABSTRACT FROM AUTHOR]

Hydrogel has been widely used in energy storage devices and flexible electronic equipment. To promote its applications, a laminar boundary layer model is proposed to analyze the velocity and temperature distributions in the mold. Based on the time distributed-order Maxwell and Cattaneo constitutive relations, the research establishes governing equations of unsteady two-dimensional incompressible viscoelastic electrically conducting hydrogel taking into account the induced magnetic field. When the magnetic Reynolds number is large enough, it is necessary to consider the magnetic diffusion in the boundary layer. The effects of thermal radiation and velocity slip are also considered at the same time. The Gauss quadrature rule is used to approximate the distributed-order integral, and then the numerical solution of the model is obtained by using the finite difference method and the L1-algorithm. The analytical solution is constructed to verify the effectiveness of the numerical solution. The results show that the fluid velocity decreases with the increment of magnetic parameter, while the induced magnetic field increases. The boundary layer thickness of velocity, induced magnetic field, and thermal becomes thinner with the enlargement of velocity and temperature relaxation time parameters. Moreover, the distributed-order and the fractional constitutive models are compared through different weight coefficients, and it is found that the fractional constitutive model obtains larger velocity and temperature distributions. [ABSTRACT FROM AUTHOR]

Electrochromic materials (ECMs), the colors of which can be electrically modulated by small driving voltages with a unique open‐circuit memory effect, are in great demand in various application fields. However, traditional ECMs exhibit a narrow modulation range of color gamut under the electric stimulus, owing to the monotonous chemical coloration in an absorption manner. Multicolor ECMs with optical nanostructures can greatly extend the color gamut by incorporating complex optical interactions such as interference and diffraction. Mie scatterer nanospheres (MSNSs) are a kind of nanospheres with unique optical structures that can simply exhibit and change vivid structural colors by adjusting their diameters. Herein, this work reports multicolor ECMs based on MSNSs with polymer shells of poly‐3,4‐ethylenedioxythiophene (PEDOT) and poly‐pyrrole (PPY). They possess a superior optical modulation capability with a wide color gamut, a fast response rate, a visible‐angle‐independence, etc. Additionally, a nano‐dispersion strategy is used to prepare mixed electrochromic pigments with a nanoscale uniformity, further broadening the color gamut tunability. Simulations in wave optics and Mie scattering theory are conducted to unveil the multicolor modulation mechanism, demonstrating the interactions of MSNSs with incident lights. This work provides a feasible approach for fabricating multicolor ECMs with more application potential. [ABSTRACT FROM AUTHOR]

Novel catalysts of strongly coupled nickel-cobalt nitrides/carbon nanocage (NiCoN/C nanocages) with good water solubility and low cost are utilized to simultaneously catalytically reduce three nitrophenol isomers (2-NP, 3-NP and 4-NP) into corresponding aminophenol (2-AP, 3-AP and 4-AP) within nearly 5 min at room temperature. It is the first report that only one reagent (dopamine) can achieve fast discrimination of three nitrophenol isomers one by one. The reduced product of 3-NP (3-AP) can selectively form fluorescent substance with dopamine with maximum emission wavelength at 465 nm. The reduced product of 4-NP (4-AP) can selectively react with dopamine to form purple solution with absorption peak at 550 nm. It achieves fluorescent detection of 3-NP from 50 nM to 1.2 μM with the limit detections (LOD) of 17 nM for 3-NP, and colorimetric detection of 4-NP from 5 μM to 200 μM with LOD of 1.7 μM. It also realizes nitrophenol detection in tap water. When 0.30, 0.60, 1.00 μM 3-NP and 10, 50, 100 μM 4-NP are added to water samples, recoveries are 98.8–104.6% for 3-NP and 98.8–101.8% for 4-NP. [Display omitted] • Novel water-soluble catalysts of NiCoN/C nanocages to reduce nitrophenol into aminophenol. • Fast fluorescent and colorimetric discrimination of three nitrophenol isomers one by one using dopamine. • Fluorescent detection of 3-NP with LOD of 17 nM and colorimetric detection of 4-NP LOD of 1.7 μM. [ABSTRACT FROM AUTHOR]

We investigate the energy band structure of nanoporous silicon thin film using first principles calculation based on density functional theory (DFT) with the generalized gradient approximation (GGA). The calculation results show that the band gaps of nanoporous silicon increase with increasing porosity, increase with decreasing the thickness of matrix layer, and almost independent of the thickness of pore layer. Moreover, the band structure of nanoporous silicon can be transformed from indirect to direct gap on thin films of (111) and (110) faces. It will be the guidance and reference for the fabrication of porous silicon optoelectronic devices. [ABSTRACT FROM AUTHOR]

Platinum nanoparticles (PtNPs)-loaded holey reduced graphene oxide framework (Pt/HGF) has been synthesized as freestanding counter electrodes (CEs) of dye sensitized solar cells (DSSCs) and methanol oxidation catalysts. PtNPs (∼2.5 nm) are uniformly incorporated into holey reduced graphene oxide framework by a solvothermal treatment. Pt/HGF possesses high specific surface area (340.65 m 2 g −1 ). Its charge transfer resistance (R CT ) at the I − /I 3 − electrolyte/CE interface reaches 1.61 Ω cm 2 , lower than that of pure Pt (2.99 Ω cm 2 ) and PtNPs loaded non-hole reduced graphene oxide (Pt/G, 2.37 Ω cm 2 ), and its R CT at the methanol electrolyte/electrode interface (0.75 Ω cm 2 ) is much lower than that of Pt/G (3.14 Ω cm 2 ), showing good electrocatalytic activity for I − /I 3 − redox reaction and methanol oxidation reaction (MOR). The assembled Pt/HGF-DSSC achieves a photoelectric conversion efficiency of 5.55% and a short-circuit current density (J sc ) of 12.27 mA cm −2 , better than those of Pt-DSSC (5.19%, 10.50 mA cm −2 ) and Pt/G-DSSC (5.12%, 11.12 mA cm −2 ). In methanol oxidation test, Pt/HGF delivers better electrocatalytic activity and stability than Pt/G. Thus, high electrocatalytic activity and efficient electron/ion transport are achieved by Pt/HGF due to the synergistic effect of well dispersed PtNPs, hierarchical holey structure, and framework, and it may serve as an alternative of pure Pt for DSSC-CEs and MOR catalysts. [ABSTRACT FROM AUTHOR]

The methyl C H bonds in the dimethylfulvene complex [η 5 ,η 1 -C 5 H 4 C(CH 3 ) 2 ][Ru(CO) 2 ][Ru(CO) 4 ] are known experimentally to be activated by the central Ru 2 unit to give the dehydrogenation product [η 5 ,η 3 -C 5 H 4 C(CH 2 ) 2 ][Ru(CO) 2 ][Ru(CO) 3 ]. The mechanistic aspects of this process are explored by a theoretical investigation of the two series of complexes [C 5 H 4 C(CH 3 ) 2 ]Ru 2 (CO) n and [C 5 H 4 C(CH 2 ) 2 ]Ru 2 (CO) n ( n = 6, 5, 4). Potential reaction intermediates with agostic hydrogen atoms as well as ruthenium carbonyl hydrides and dihydrogen complexes are found. [ABSTRACT FROM AUTHOR]

First-principles calculation based on density functional theory (DFT) with the generalized gradient approximation (GGA) were carried out to investigate the energy band gap structure of Si and Ge nanofilms. Calculation results show that the band gaps of Si(111) and Ge(110) nanofilms are indirect structures and independent of film thickness, the band gaps of Si(110) and Ge(100) nanofilms could be transfered into the direct structure for nanofilm thickness of less than a certain value, and the band gaps of Si(100) and Ge(111) nanofilms are the direct structures in the present model thickness range (about 7 nm). Moreover, the changes of the band gaps on the Si and Ge nanofilms follow the quantum confinement effects. It will be a good way to obtain direct band gap emission in Si and Ge materials, and to develop Si and Ge laser on Si chip. [ABSTRACT FROM AUTHOR]

Based on 16 years of Tropical Rainfall Measuring Mission (TRMM) data and NCEP Climate Forecast System Reanalysis data, the most intense convective systems (ICSs) along the southern Himalayan front (SHF) are studied using the multivariate techniques of principal component analysis in T mode and k-means cluster analysis. Three clusters, classified according to the near-surface fields of wind, specific humidity, convective available potential energy, and convective inhibition, correspond to the premonsoon (March-May), the establishment of the monsoon (late May-early June), and the Indian summer monsoon itself (June-September), respectively. The location of ICSs along the SHF is closely related to the establishment of the transport passage from the eastern SHF to the northwestern SHF along the Himalayas. During the premonsoon, the southwesterly wind is weak and moist air from the Bay of Bengal is transported to the eastern SHF, where ICSs are densely distributed. The oceanic southwesterly wind is enhanced and the transport passage extends to the central SHF during the monsoon establishment period, when ICSs distribute over the whole SHF homogeneously. The southwesterly wind is the strongest and the transport passage extends to the westernmost SHF after the monsoon is established, when ICSs mainly concentrate over the concave indentation region. Backward trajectory analysis confirms that, besides the local environment, the moisture transport from the Arabian Sea (17%) and the Bay of Bengal (9%) are two important long-range transport pathways for the summer monsoon ICSs at the western end of the SHF. [ABSTRACT FROM AUTHOR]

South Asian monsoon convection in the southern Himalayan front (SHF) plays an important role in the entry of South Asia pollutants to the Qinghai-Tibetan Plateau and even to the stratosphere. Combining the 16-yr TRMM observations and Indian summer monsoon (ISM) index, the responses of extreme convective storms to the ISM are investigated. The results showed that the top height of convective storms increases gradually while their convective intensity weakens with the evolution from pre-monsoon to monsoon season. The establishment period of ISM (late May to early June) is found to be an important period for convective storms in the SHF. Not only does the frequency of storms occur more frequently, but also the convective intensity of storms is stronger compared with pre-monsoon and monsoon seasons. The ISM is proved to have an important impact on the formation of convective storms in northwestern inland Indian subcontinent, dominated by the water vapor supply, rather than the 'juicy' eastern SHF. Cloud top height of storms is more sensitive to the strength of ISM than the convective intensity. The water vapor transportation originated from the Bay of Bengal have more significant contribution in convective storm formation there than that from Arabian Sea. In stronger ISM years, the southerly meridional wind component over the Bay of Bengal is stronger, which forces more water vapor to be transported to further inland areas along the Himalayas. Together with the warm center and anticyclone in upper troposphere, resulting in convective storms in the westernmost of SHF occur more frequently and can grow up to higher top heights. • The ISM establishment period from late May to early June is a noteworthy period for extreme convection along the Himalayas. • The ISM significantly affects convective storms in northwest inland of the Indian subcontinent, but not in the eastern area. • Cloud top height of convection in northwest Indian subcontinent is more sensitive to ISM strength than convective intensity. [ABSTRACT FROM AUTHOR]

Diurnal and seasonal variation, intensity, and structure of deep convective systems (DCSs; with 20-dB Z echo tops exceeding 14 km) over the Tibetan Plateau-South Asian monsoon region from the Tibetan Plateau (TP) to the ocean are investigated using 14 yr of Tropical Rainfall Measuring Mission (TRMM) data. Four unique regions characterized by different orography are selected for comparison, including the TP, the southern Himalayan front (SHF), the South Asian subcontinent (SAS), and the ocean. DCSs and intense DCSs (IDCSs; with 40-dB Z echo tops exceeding 10 km) occur more frequently over the continent than over the ocean. About 23% of total DCSs develop into IDCSs in the SHF, followed by the TP (21%) and the SAS (15%), with the least over the ocean (2%). The average 20-dB Z echo-top height of IDCSs exceeds 16 km and 9% of them even exceed 18 km. DCSs and IDCSs are the most frequent over the SHF, especially in the westernmost SHF, where the intensity-in terms of strong radar echo-top (viz., 40 dB Z) height, ice-particle content, and lightning flash rate-is the strongest. DCSs over the TP are relatively weak in convective intensity and small in size but occur frequently. Oceanic DCSs possess the tallest cloud top (which mainly reflects small ice particles) and the largest size, but their convective intensity is markedly weaker. DCSs and IDCSs show a similar diurnal variation, mainly occurring in the afternoon with a peak at 1600 local time over land. Although most of both DCSs and IDCSs occur between April and October, DCSs have a peak in August, whereas IDCSs have a peak in May. [ABSTRACT FROM AUTHOR]

Precise adjustment of the electronic structure of conductive MOFs load materials plays an important role in the design of electrocatalysts. In this paper, a hydrogen evolution catalyst in the full pH range was prepared by using a rapid microwave method to partially carbonize conductive MOFs materials and quickly anchoring small metal Ru nanoparticles on them. [Display omitted] • Ru@p-Co 3 HHTP 2 is quickly prepared by a microwave solid-phase pyrolysis method. • Partial carbonization and SMSI in microwave improves stability and reactivity. • This catalyst has excellent hydrogen evolution performance in the full pH range. • DFT calculations and experiments revealed the synergy between Ru and p-Co 3 HHTP 2. Conductive metal organic frameworks (MOFs) have limited their long-term development in the actual electrocatalytic test process due to their low activity and poor stability. Here, for the first time, ultra-small Ru nanoparticles supported by a novel conductive MOF material (Co 3 HHTP 2) were synthesized simply and quickly (60 s) using only a household microwave oven. In this process, the conductive MOF is partially carbonized, strong metal carrier interaction (SMSI) is generated, and Ru nanoparticles are firmly attached to the carrier to form Ru@p-Co 3 HHTP 2. The Ru@p-Co 3 HHTP 2 -3.2% catalyst has excellent hydrogen evolution performance in the full pH range. Density functional theory calculations (DFT) result shows that the partial carbonization of the conductive MOF and the presence of SMSI promote the charge transfer at the interface between Ru nanoparticles and Co 3 HHTP 2 , which not only synergistically accelerates the water dissociation step and reduces the hydrogen adsorption energy, but also enhances the stability of the catalyst. [ABSTRACT FROM AUTHOR]

Abstract: The characterization of atmospheric conditions at different scales and their relationships to meteorological phenomena is a basic tool for improving the understanding and prediction of severe atmospheric events. Hailstorms are relatively common in southern Europe during summer, causing significant adverse impacts to property and infrastructure. This paper provides a spatiotemporal characterization of hail falls in southwestern France between 2000 and 2010, using the hail pad network operated there by the Association Nationale d'Etude et de Lutte contre les Fléaux Atmosphériques (ANELFA). This area is greatly affected by hailstorms. It was observed that the greatest incidence and severity of hail was in the central Pyrenees during May and July, with decreasing frequency and intensity toward the Atlantic coast. We selected 100 events in which severe hailstorms were reported, to study atmospheric parameters responsible for their occurrence. We performed mesoscale simulations with the WRF model, using parameterizations and fields reported in previous studies. By applying principal component analysis (PCA) and cluster analysis, we obtained three configurations to help establish relationships with the spatiotemporal incidence of hailstorms. The method and results obtained improve knowledge of the conditions favorable for hailstorms in southwestern France. This allows better hail prediction by relating atmospheric conditions with characteristics of hail precipitation on the ground. [Copyright &y& Elsevier]

Using 12 years of data from the Tropical Rainfall Measuring Mission (TRMM)-based Precipitation Radar (PR), spatial and diurnal variations of deep convective systems (DCSs) over the Asian monsoon region are analyzed. The DCSs are defined by a 20 dBZ echo top extending 14 km. The spatial distribution of DCSs genesis is also discussed, with reference to the National Centers for Environmental Prediction (NCEP) reanalysis data. The results show that DCSs occur mainly over land. They concentrate in south of 20°N during the pre-monsoon season, and then move distinctly to mid-latitude regions, with the most active region on the south slope of the Himalayas during monsoon season. DCSs over the Tibetan Plateau are more frequent than those in central-eastern China, but smaller in horizontal scale and weaker in convective intensity. DCSs in central-eastern China have more robust updrafts and generate more lightning flashes than in other Asian monsoon regions. The horizontal scale of DCSs over the ocean is larger than that over the other regions, and the corresponding minimum infrared (IR) brightness temperature is lower, whereas the convective intensity is weaker. Continental DCSs are more common from noon through midnight, and DCSs over the Tibetan Plateau are more frequently from noon through evening. Oceanic DCSs frequency has a weaker diurnal cycle with dawn maximum, and diurnal variation of DCSs over the tropical maritime continent is consistent with that over the continent. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) are in great demand in many fields because of their unique properties such as high conductivity, chemical stability, lightweight, and high strength. They also received much attention in optical‐related fields because of the super‐black characteristics under visible light and the photothermal effect of infrared light. Recently, the coloration of CNTs under visible light is realized by a simple liquid phase method with the help of silica photonic crystal (PC) coatings. However, the response modulation such as the photoluminescence (PL) property of CNTs to the infrared and ultraviolet (UV) bands is not yet studied. Herein, silane functionalized carbon dots (SiCDs) are introduced into silica PCs, and successfully realized the structural coloration and PL of CNT fibers (CNTFs). The optical and fluorescence visualization of single CNTs and suspended CNT networks (SCNTNs) is also realized with the assistance of SiCDs droplets. These SiCDs‐decorated SiPCs‐coated CNTFs (SiCDs@SiPCs‐CNTFs) exhibit an up/down‐conversion PL response, and the excitation light source can be UV light, visible light, and near‐infrared laser. The structural coloration and the development of new PL properties will promote the wide applications of PL carbon hybrid materials in many fields such as smart displays, intelligent textiles, anti‐counterfeiting, etc. [ABSTRACT FROM AUTHOR]

Lightning activity over the Tibetan Plateau, which has an average altitude of higher than 4000 m above sea level, is investigated by using 20-year (1995–2014) LIS/OTD data. The effect of surface thermodynamics on lightning activity is examined for four sub-regions across the plateau based on the NCEP reanalysis data. The average lightning flash density over the entire Tibetan Plateau is 2.5 fl·km−2 yr−1, and the maximum flash density is 7.7 fl·km−2 yr−1 at eastern plateau. The geographical distribution of lightning flash density shows a gradual decrease from east to west across the Tibetan Plateau, from 4.3 fl·km−2 yr−1 on average over the Eastern Tibetan Plateau to 1.7 fl·km−2 yr−1 over the Western Tibetan Plateau. Over the plateau's main highland (>4500 m), there is a local maximum value of 5.7 fl·km−2 yr−1 in the center area of Nagqu. Lightning activity over the Tibetan Plateau mainly occurs in boreal summer, and 96.8% of the annual flashes occur during May–September. There is more lightning in the relatively dry spring, even in summer, over the main highland of the Tibetan Plateau. The results show that humidity and sensible heat fluxes play a vital role in the occurrence of lightning over the Tibetan Plateau. A new parameter, product of rainfall, Bowen ratio (defined as the ratio of the sensible heat fluxes to latent heat fluxes) and surface specific humidity, is proposed and shows a better correlation with lightning activity, generally displaying a larger correlation coefficient than rainfall alone or other parameters over the study sub-regions. • The flash density over the Tibetan Plateau decreases gradually from east to west. • A pre-monsoon season "lightning anomaly" is universal over the TP main highland. • A proposed new parameter best reflects lightning activity throughout the plateau. [ABSTRACT FROM AUTHOR]

Carbon based supercapacitor suffers from low energy density due to inefficient electrical double-layer storage mechanism. Herein, sp3-defect engineered sp2 carbon framework with hierarchical porous architecture (HCF) is developed via a one-step chemical vapor deposition (CVD) method for high energy density supercapacitor. Theoretical calculations are performed firstly and results reveal that the sp3-defects in host sp2 carbon sheets promote the sodium-ion storage performance attributed to the reduced energy barrier of sodium-ion adsorption and increased density of states around Fermi level. The HCF is extensively characterized and the results show that the density of sp3-defects and hierarchical micro-meso-macropore size of HCF can be well tuned by regulating the CVD temperature. Owing to reasonably engineered sp3-defects (~32.8 at%), well-defined multiscale pore architectures and wide interlayer in HCF, extra pseudocapacitive sodium-ion storage sites are obtained and therefore a capacitance up to 558.8 F/g is achieved. The resultant HCF based symmetric supercapacitor device gives a high energy density of 38.76 Wh/kg at a power density of 375.04 W/kg and still retains 30.00 Wh/kg at a high power density of 5970.15 W/kg. This work provides a facile strategy to explore the intrinsic defect in carbon electrode materials for high performance energy storage systems. Image 1 • DFT calculation demonstrates that sp3-defects contribute to improved Na+ storage. • sp3-Defect rich porous carbon framework (HCF) is developed for supercapacitors. • The sp3-defect density and hierarchical pore-size of HCF can be easily tunable. • HCF employed as supercapacitor electrode show a high capacitance of 558.8 F g-1. • HCF based symmetric supercapacitor delivers a high energy density of 38.76 Wh kg−1. [ABSTRACT FROM AUTHOR]

Vigorous convective storms can not only produce severe destructive weather events and lead to huge damages, but also play a vital role in stratosphere–troposphere exchange (STE). Based on 16-yr Tropical Rainfall Measuring Mission (TRMM) observational data, global geographical distribution of extremely deep and intense convective storms has been investigated. The results show that convective storms are mainly distributed in the tropics, with the largest storm event density located in tropical Africa, tropical Americas and the Maritime Continent. However, compared to convective storms, the most intense and deepest convective storms present a distinctly different geographical distribution pattern, which is true even if the same convective storm samples are used. Overall, tropical Africa is the only region in the world where the distributions of deep and intense convective storms overlap. Other than that, convective storms in the Maritime Continent region are characterized by large convective depth but weak convective intensity, while the opposite is true in subtropical land regions. The top 1% deep convective storms occur most frequently in boreal winter (48%) and spring (36%), and are mainly distributed in the Maritime Continent and tropical Africa. Those most intense convective storms show a weak seasonal variation in quantity while their distributions are significantly different from season to season. Further analysis reveals that convective properties of storms in different regions are distinctly different, and even different in the same region such as tropical Africa but in different seasons. This result suggests that although the formation of convective storm requires sufficient water vapor supply and instable atmospheric conditions, deep convection needs more water vapor supply to develop compared to intense storms. • The geographic distributions of deep and intense convective storms exhibit distinctly different patterns. • Convective storms are strong in convective depth in maritime continent, but strong in convective intensity in subtropical continent. • Deep convection is more likely to occur in a more humid environment than intense storms. [ABSTRACT FROM AUTHOR]

• A pre-assembly strategy is developed for graphene based hybrid frameworks (GHFs). • Four GHFs (G/X, X = SWNTs, MoS 2 , VN, and SiC) were synthesized by our strategy. • A grain boundary-induced-graphene growth mechanism for GHFs is concluded. • G/SWNT and G/MoS 2 are used as self-standing supercapacitor electrodes. • Both G/SWNT and G/MoS 2 show high capacitance (232.4 and 331.1 F g−1, respectively). Three-dimensional graphene based hybrid frameworks (GHFs) prepared by chemical vapor deposition (CVD) have shown extraordinary promise for energy-storage but are usually limited by the lack of facile and efficient preparation strategies. Herein, a facile and general strategy is developed to synthesize near-nanoporous GHFs via mechanically-assisted pre-assembly and CVD processes. Functional nanomaterials (FNMs) are pre-filled into copper-nanopowders (CuNPs) as semi-sacrificial templates of CVD-graphene. A grain boundary-induced-graphene growth mechanism is demonstrated: during CVD process, graphene preferentially nucleates/grows along the abundant grain-boundaries formed by the fusion of CuNPs. Meanwhile, these FNMs are firmly combined with graphene-frameworks by π-π interactions and/or van der Waals forces, thus GHFs are constructed. Furthermore, two typical GHFs containing single-wall carbon nanotubes and molybdenum disulfide (defined as G/SWNT and G/MoS 2 , respectively) are used as freestanding supercapacitor-electrodes: Both GHFs exhibit high capacitance (232.4 F g−1 for G/SWNT and 331.1 F g−1 for G/MoS 2) and impressive stability (96.62% capacitance-retention after 10,000 cycles for G/SWNT; 92.18% retention after 5000 cycles for G/MoS 2), which due to the firmly combination of active FNMs and near-nanoporous graphene-frameworks by our strategy. These results suggest that our pre-assembly strategy can prepare various GHFs with excellent energy-storage performance. [ABSTRACT FROM AUTHOR]

Osteoarthritis (OA) is a globally prevalent disease that poses significant challenges to the daily work and life of patients. Viscosupplementation is one of the most commonly used drug treatments for OA, which involves injecting hyaluronic acid (HA) into the joint cavity to alleviate synovial inflammation. The current research aims to explore the rheological and thermal behavior of HA between joints by studying the axisymmetric squeezing flow and heat transfer of incompressible Maxwell fluid under the action of static magnetic field between two rigid spheres with partial wall slip. The analytical solutions for velocity and temperature are obtained by using the Laplace integral variational theory. Detailed explanations are provided on the effects of different fluid parameters on velocity and temperature, presented in the form of charts. It can be shown that as the magnetic field intensity increases, the viscosity of HA increases with the increasing of relaxation time, thereby fluid motion is weakened and a strong damping effect is produced. As the frequency of joints motion increases, the velocity distribution becomes more uniform in the central region, and the overall distribution deviates from a parabolic distribution. In addition, as Reynolds number, Prandtl number and squeezing depth increase, the heat transfer capacity of the fluid decreases, resulting in a lower temperature at the top wall and a higher temperature at the bottom wall. This study provides theoretical support for exploring the rheological and thermal behavior characteristics of HA in the treatment of OA. [ABSTRACT FROM AUTHOR]

Electrocatalytic nitrogen reduction reaction (NRR) has been an important area for many scientists. However, high voltage requirements, low NH3 yield, and poor stability remain the biggest challenges for NRR. Here, novel high‐entropy alloys RuFeCoNiCu nanoparticles with small size (≈16 nm) and uniformity, prepared in oil phase at atmospheric pressure and low temperature (≤250 °C) are reported for the first time and are applied to NRR. According to the experiments, there is a high NH3 yield at a low overpotential. It has a surprising NH3 yield of 57.1 µg h–1mgcat−1 (11.4 µg h–1 cm–2) at 0.05 V versus RHE in 0.1 m KOH, and the corresponding Faradaic efficiency reaches 38.5%, which is the electrocatalyst with the highest NH3 yield at the voltage of 0.05 V versus RHE reported so far. Similarly, the material also exhibits excellent electrochemical properties in other electrolytes such as 0.1 m Li2SO4, 0.1 m Na2SO4, and 0.1 m HCl electrolytes. Besides, after the 100 h test, only slightly diminished in activity. Theoretical calculation shows that Fe surrounded by alloy metals is the best site for N2 adsorption and activation. Co‐Cu and Ni‐Ru couples show an excellent capacity to surface hydrogenation at a low overpotential. [ABSTRACT FROM AUTHOR]

The geometries and energetics of the bis(bicyclo[3.2.1]octa-2,6-dien-4-yl) complexes of the first row transition metals, (bcod)2M (M = Ti to Cu), including the experimentally known chromium and iron derivatives, have been examined by density functional theory. Sandwich-type structures in which each bcod ligand is bonded to the central metal atom through both the trihapto allylic unit and the double bond are energetically preferred for the metals from titanium to iron. However, higher energy (bcod)2M (M = V, Cr, Mn) isomers are found in which one of the bcod ligands is bonded to the central metal atom through the trihapto allylic unit and an agostic hydrogen from the CH2 bridge leaving an uncomplexed C＝C double bond. The experimentally known iron complex (bcod)2Fe, an analogue of ferrocene, has the favored 18-electron configuration and a singlet spin state. For the metals to the left of iron from manganese to vanadium the energetically preferred spin states range from doublet to quartet, respectively, corresponding to holes in the closed shell 18-electron configuration. However, a singlet structure is preferred for (bcod)2Ti despite the 14-electron configuration of the central titanium atom. The (bcod)2M (M = Co, Ni, Cu) derivatives of the electron richer later transition metals are characterized by several structures of different types at closely spaced energies in which at least one of the bcod ligands is only partially bonded to the central metal atom. [ABSTRACT FROM AUTHOR]

A ratiometric fluorescent thermometer (RFT) based on the frustrated static excimers (FSEs) of DEH-PDI (N,N′-di(2-ethylhexyl)-3,4,9,10-perylenetetracarboxylic diimide) was designed and synthesized. The RFT exhibited ultrahigh sensitivities, which far exceed the existing RFTs in the physiological temperature range. The RFT also showed outstanding precisions, stability, and an obvious thermochromism in the temperature range. [ABSTRACT FROM AUTHOR]

Ultralong carbon nanotubes (CNTs) are believed to be ideal candidates for various high‐end applications because of their macroscale lengths, perfect structures, and excellent mechanical and electrical properties. The key to the wide application of ultralong CNTs is their controlled synthesis and mass production. Ultralong CNTs usually follow a flying kite‐like growth mechanism, during which process there exists a thermal buoyancy that keeps ultralong CNTs floating in the gas flow. However, it remains vague for a long time about the origin of this thermal buoyancy. Herein, a simple and quantitative heat balance model is proposed to describe the inherent thermal effect of substrates, which explains the origin of the temperature difference between the substrate and the gas flow. The inherent thermal effect is found to be positively correlated with the emissivity of the substrates. Then, the local temperature gradient induced by the inherent thermal effect is found to result in both natural convection and thermophoresis. Thermophoretic force is proven to be the dominant driving force for lifting the ultralong CNTs up from the substrates. By utilizing the inherent thermal effect and designing the local temperature distribution, the areal density and orientation of ultralong CNT arrays are modulated. [ABSTRACT FROM AUTHOR]

The synthesis of intermetallic compounds with small size and defective structures is rigorous challenge. In this work, the small size (< 10 nm) of intermetallic PdM (M = Pb, Sn, In) with ordered vacancies (OVs) are successfully prepared by ultrafast and solvent-free microwave method for the first time. With the optimized vacancies, atomic arrangement and components, the intermetallic OVs-Pd 3 Pb-2 shows the best nitrogen reduction (NRR) performance among intermetallic OVs-PdM (M = Sn, In), intermetallic OVs-Pd 3 Pb with various degrees of vacancies, intermetallic Pd 3 Pb with vacancies-free, Pd 3 Pb/CNT and Pd/CNT in Li 2 SO 4 solution. In situ Raman spectroscopy, in situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) technique and density functional theory (DFT) further demonstrate the synergy mechanism of good NRR activity at low overpotentials on OVs-Pd 3 Pb-2 catalysts. In this work, the small size (< 10 nm) of intermetallic PdM (M = Pb, Sn, In) with ordered vacancies (OVs) are gained for the first time. The intermetallic OVs-Pd 3 Pb-2 shows the outstanding electrocatalytic NRR performance. [Display omitted] • Ultrasmall intermetallic PdM with vacancies are gained for the first time. • This catalyst was prepared by solvent-free microwave method. • TOF of OVs-Pd 3 Pb-2 is 12.4 times than Pd 3 Pb without vacancies. • In situ Raman/ATR-SEIRAS/DFT demonstrate the synergy mechanism for NRR. [ABSTRACT FROM AUTHOR]

Preparation of low-cost, highly activity and stable bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in acidic media has great challenges. Here, a series of M-Ru/RuO 2 @CNT (M = Mn, Cd, Cu) bifunctional catalysts were synthesized by doping and strong metal-support interaction (SMSI) strategies to improve the activity and stability of the catalysts. The experiment results show that the optimized Mn–Ru/RuO 2 @CNT catalyst with ultra-small particle size (2.5 nm) has the best catalytic performance, and the OER and HER tests at 10 mA cm−2 in 0.5 M H 2 SO 4 solution show excellent overpotentials of 177 mV and 30 mV respectively, which are better than most of the catalysts reported recently. In addition, current densities of 10 mA cm−2 and 100 mA cm−2 can be obtained at 1.43 V and 1.51 V when measuring water splitting and can last up to 100 h at a current density of 100 mA cm−2. And this is the first time to achieve the stability of acid water splitting of Ru-based catalyst under large current density. Density functional theory (DFT) calculations show that after manganese doping, the electronic structure is changed by charge redistribution between doped ions and ruthenium-based catalysts containing heterojunctions, and the binding energy of intermediates is optimized to improve the catalytic activity; the stability of the catalyst is improved by increasing the formation energy of ruthenium vacancy and preventing the formation of ruthenium vacancy. In this paper, bifunctional Mn–Ru/RuO 2 @CNT catalysts with a particle size of 2.5 nm were successfully prepared, and the long-time stability of Ru-based catalysts in acidic media at high current density was achieved for the first time by doping and strong metal-support interaction strategies. The excellent performance comes from the effective modulation of electrons between the manganese and ruthenium groups and the interaction between the metal particles and the support to produce the excellent performance. [Display omitted] • M-Ru/RuO 2 @CNT catalysts containing Ru/RuO 2 heterojunctions have been synthesized by doping and SMSI strategies. • Mn-Ru/RuO 2 @CNT shows the best HER, OER and overall water splitting (OWS) performance in acidic media. • DFT showed that doping reduces the dissolution of the active site and improves the catalyst performance. [ABSTRACT FROM AUTHOR]

Rational design of nanostructures with excellent activity and stability for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) to realize efficient hydrogen production is essential for renewable energy development and conversion. Here, we have designed a special pyrolysis reduction method for the synthesis of CoPt3 nanoparticles (NPs) embedded in N‐doped carbon nanospheres (CoPt3@NC). In this process, a facile impregnation combined with pyrolysis reduction strategy is carried out to produce well‐dispersed CoPt3 nanoparticles within the N‐doped carbon, and the resulting CoPt3@NC nanospheres with trace Pt content exhibit superior HER and OER activity to pure Pt@NC, which needs an ultralow overpotential of 65 mV and 360 mV to drive 10 mA/cm2 in 1.0 M KOH, respectively, and also with excellent long‐term durability. The excellent HER and OER activities of CoPt3@NC nanospheres are mainly ascribed to the high surface area, N‐doping, and synergistic effect between catalyst and carrier. This work provides a feasible strategy to design carbon‐based heterostructures with high catalytic activity and stable properties. [ABSTRACT FROM AUTHOR]

HEPi/C hybrid nanosheets exhibit excellent HER performance in 0.5 M H 2 SO 4 solution, the overpotential of 40 mV at 10 mA cm−2 is lower than that of commercial Pt/C (η 10 = 48 mV), and has excellent catalytic stability. More interestingly, at an overpotential of 50 mV, the mass activity of the HEPi/C hybrid nanosheets is as high as 1.6 A mg−1 noble metal. [Display omitted] • The first synthesis of high-entropy phosphate/carbon (HEPi/C) hybrid nanosheets. • HEPi/C hybrid nanosheets can be prepared on a large scale. • HEPi/C hybrid nanosheets show excellent HER performance in acidic solutions. It is a huge challenge to develop acidic hydrogen evolution reaction (HER) non-platinum (Pt) catalysts with high activity and excellent stability. In this work, a two-step method was used to synthesize high-entropy phosphate/carbon (HEPi/C) hybrid nanosheets for the first time. First, high-entropy metal–organic framework (HE-MOF) nanosheets were synthesized by an entropy-driven mechanochemical method at room temperature, and then high-temperature phosphating is performed. HEPi/C hybrid nanosheets exhibit excellent HER performance in 0.5 M H 2 SO 4 solution, the overpotential of 40 mV at 10 mA cm−2 is lower than that of commercial Pt/C (η 10 = 48 mV), and has excellent catalytic stability. More interestingly, at an overpotential of 50 mV, the mass activity of the HEPi/C hybrid nanosheets is as high as 1.6 A mg−1 noble metal. This work provides an attractive non-Pt-based material for acidic HER, and also provides a new idea for designing highly efficient and stable hybrid materials composed of high-entropy materials and carbon for electrocatalytic applications. [ABSTRACT FROM AUTHOR]

Dual‐band electrochromic (EC) smart windows, which can selectively modulate visible (VIS) and near‐infrared (NIR) light are widely regarded as one of the most attractive options to drastically reduce energy consumption in modern buildings. However, dual‐band EC smart windows still face many challenges such as weak modulation selectivity between VIS and NIR bands, low switching speed, poor durability, and high cost. Here, inspired by pine needles, a unique pine‐needle‐like (PNL) W18O49/TiO2 heterostructure is rationally constructed with W18O49 nanothorns (as branches) and TiO2 nanofibers (as backbones). The PNL‐W18O49/TiO2 heterostructures exhibit superior dual‐band EC performance in both VIS and NIR bands, which can block up to 81.4% of the VIS light at 633 nm and 91.3% of NIR at 1800 nm, and they also show extremely short bleaching/coloring time (0.9/1.2 s) and excellent stability (85% of capacity retention after 20 000 cycles) in a narrow potential window of −0.8 to 0.6 V. Besides, abundant patterned EC layers on a fluorine‐doped‐tin‐oxide‐coated conductive glass and flexible polyester conductive films can also be realized. This work provides an effective way for dual‐band EC materials' design and their further development in smart windows and intelligent displays. [ABSTRACT FROM AUTHOR]

Reducing energy consumption is one of the major concerns in modern building design and construction because buildings account for ≈40% of the total energy consumption in modern society. Among various technologies for saving energy, electrochromic smart windows are considered as a highly promising one. Except for the application in saving energy, electrochromism has also attracted extensive attention in many other fields, such as, anti‐glare rearview mirrors, displays, military camouflage, flexible wearable fabric, etc. However, there are still many challenges needed to be solved, such as, the response rate and durability of electrochromic materials (ECMs). The transmission rate of ions in ECMs determines the response rate of the whole electrochromic device. Besides, the embedding depth and total amount of ions directly affect the contrast, durability, and coloration efficiency of ECMs. It is crucial to select suitable electrolyte ions to obtain high‐efficiency ECMs. Here, the challenges in ECMs based on ions insertion/extraction are presented, which are focused on advanced nanostructured ECMs' design and electrochromic devices' practical application. Recent advances in ECMs are presented to discuss the important questions, which are especially focused on the connection between suitable ions and advanced nanostructural ECMs. Finally, a perspective for next‐generation electrochromic devices is presented. [ABSTRACT FROM AUTHOR]

The fast visualization and manipulation of individual carbon nanotubes (CNTs) has always been a significant technology for their fundamental research. Here, a fast and facile approach is proposed to realize the optical observation of individual suspended CNTs and CNT networks under conventional optical microscopes with the assistance of tar nanodroplets from smoke. The nanodroplets deposited on CNTs render them with strong light scattering to visible light, thus making the CNTs visible under optical microscopes. This visualization method is controllable, environmentally friendly, low‐cost, and can be completed in just a few seconds in ambient conditions. Besides, the tar nanodroplets can be easily removed from the CNTs by laser irradiation. More importantly, the smoke sources are widely available and there are no strict requirements for operating conditions. This smoke‐assisted visualization method shows great potential in the fundamental research of CNTs. [ABSTRACT FROM AUTHOR]

Structural colors, generated by the interaction of interference, diffraction, and scattering between incident light and periodic nanostructured surfaces with features of the same scale with incident visible light wavelengths, have recently attracted intense interest in a wide range of research fields, due to their advantages such as various brilliant colors, long-term stability and environmental friendliness, low energy consumption, and mysterious biological functions. Tremendous effort has been made to design structural colors and considerable progress has been achieved in the past few decades. However, there are still significant challenges and obstacles, such as durability, portability, compatibility, recyclability, mass production of structural-color materials, etc., that need to be solved by rational structural design and novel manufacturing strategies. In this review, we summarize the recent progress of bio-inspired structural colors and their applications. First, we introduce several typical natural structural colors displayed by living organisms from fundamental optical phenomena, including interference, diffraction grating, scattering, photonic crystals effects, the combination of different phenomena, etc. Subsequently, we review recent progress in bio-inspired artificial structural colors generated from advanced micro/nanoscale manufacturing strategies to relevant biomimetic approaches, including self-assembly, template methods, phase conversion, magnetron sputtering, atomic layer deposition, etc. Besides, we also present the current and potential applications of structural colors in various fields, such as displays, anti-counterfeiting, wearable electronics, stealth, printing, etc. Finally, we discuss the challenges and future development directions of structural colors, aiming to push forward the research and applications of structural-color materials. [ABSTRACT FROM AUTHOR]

Various electrocatalyst adjustment methods have been reported with the efforts of plenty of researchers, such as element doping, defect, control crystalline phase, surface modification, etc. However, systematic studies on the relationship between the facets of electrocatalysts and the activity of NRR have not been reported. Pd nanocrystals are systematically studied herein, which selectively expose the (100) facet, (111) facet, and (110) facet (each of which behaves as a cube, octahedron, and rhombic dodecahedron) for NRR at mild conditions. Experimental data show that the NH3 yield of Pd cubes is 24.3 μg mg‐1cat h‐1 at 0 V vs reversible hydrogen electrode and the Faradaic efficiency is 36.6% in 0.1 m Li2SO4 electrolyte, which are 2.7 and 5.3 times higher than Pd octahedrons and Pd rhombic dodecahedrons. Meanwhile, it is also one of the best catalytic materials to realize high activity at low overpotentials ever reported. Furthermore, Pd cubes show extraordinary stability for NRR after a long‐time stability test. Density functional theory calculations reveal the remarkable NRR performance of Pd (100) can be attributed to the lower energy barrier of *NNH generation and the lower energy barrier for producing NH3 from *NH3 (the rate determining step). [ABSTRACT FROM AUTHOR]

Three-dimensional nitrogen-doped graphene/reduced hydroxylated carbon nanotube composite aerogel (NG/CNT-OH) with unique hierarchical porosity and mechanical stability is developed through a two-step hydrothermal reaction. With plenty of exposed active sites and efficient multidimensional transport pathways of electrons and ions, NG/CNT-OH exhibits great electrocatalytic performances for I − /I 3 − redox couple. The subsequent compressed NG/CNT-OH papers possess high electrical conductivity and good flexibility, thus generating high-performance flexible counter electrodes (CEs) with transparent conducting oxide free (TCO-free) for dye-sensitized solar cells (DSSCs). The flexible NG/CNT-OH electrodes show good stability and the DSSCs with the optimized NG/CNT-OH CE had higher short-circuit current density (13.62 mA cm −2 ) and cell efficiency (6.36%) than DSSCs using Pt CE, whereas those of the DSSCs using Pt CE were only 12.81 mA cm −2 and 5.74%, respectively. Increasing the ratio of hydroxylated carbon nanotubes (CNT-OH) to the graphene oxide (GO) in the reactant would lead to less content of doped N, but better diffusion of electrolyte in the CEs because of more complete GO etching reaction. The design strategy presents a facile and cost effective way to synthesis three-dimensional graphene/CNT composite aerogel with excellent performance, and it can be potentially used as flexible TCO-free CE in other power conversion or energy storage devices. [ABSTRACT FROM AUTHOR]

Superhydrophobicity depends mainly on the microstructures of a surface. Although the superhydrophobic surfaces (SHS) have been fabricated, micro-mechanisms responsible for its contact angle hysteresis (CAH) and free energy barrier (FEB) still need to be deeply investigated. For this reason, we attempt to compare the superhydrophobicity of the different hierarchy for the SHS based on a three-dimensional (3-D) pillar model by a more practical thermodynamic method. Therefore, general relationships between the superhydrophobic property and the proposed surface microstructures are also established based on the CAH phenomena together with a transient equation for describing the relationships between advancing/receding CAs and the static apparent CAs. The simulation suggests that the superhydrophobicity of two-step/three-step surfaces is significantly/slightly improved in comparison with those of one-step/two-step surfaces respectively; therefore designing for a three-step surface is again unnecessary. [ABSTRACT FROM AUTHOR]

In this work, the ultrathin (0.9 nm) of interstitial metallene with controlled vacancies are successfully prepared for the first time. The interstitial V Pd -PdH 0.41 metallene displays a unique nitrogen reduction (NRR) activity in Li 2 SO 4 solution. [Display omitted] • Ultrathin interstitial metallene with vacancies are obtained for the first time. • TOF of V Pd -PdH 0.41 is 14.97 times than Pd NSs without vacancies. • This catalyst has great stability during the continuous test for 100 h. • In situ Raman/ATR-SEIRAS/DFT display the synergy mechanism for NRR. It is of great significance to controlled synthesis of high activity, selectivity and durable electrocatalysts. In this work, for the first time, the ultrathin (0.9 nm) of interstitial metallene with controlled vacancies and lattice hydrogen atoms are successfully gained. With the optimal lattice hydrogen atoms and composition, the interstitial V Pd -PdH 0.41 metallene exhibits the great nitrogen reduction (NRR) activity in Li 2 SO 4 solution, among interstitial PdH x with different extent of vacancies, interstitial PdH 0.41 without vacancies and Pd nansheets. The density functional theory (DFT), in situ Raman and Attenuated total reflection surface-enhanced infrared absorption spectrum (ATR-SEIRAS) tests further display that the V Pd on the interstitial V Pd -PdH 0.41 metallene can urges the adsorption and arousal of N 2 , while lattice hydrogen atoms as active hydrogen source to follow an association mechanism rather than a dissociation mechanism, showing nice NRR performance at low overpotential. [ABSTRACT FROM AUTHOR]

It is an insurmountable challenge to synthesize carrier-supported ultra-small immiscible alloy catalyst with simple one-step method today. Here, we creatively report the first preparation of immiscible Ru-based alloys (RuRE-rGO NPs, RE=Gd, Er, Yb, La) with ~5 nm by solvent-free microwave reduction. Additionally, in alkaline electrocatalytic hydrogen evolution reaction (HER), RuGd-rGO NPs performed admirable (η = 12 mV at 10 mA cm−2, TOF=30.6 H 2 s−1 at 0.1 V), which also can be stable for 500 h even if it provides industry-related current density of 500 mA cm−2. Density functional theory further indicates that from initial to final state of the reaction, RuGd-rGO NPs have large exothermic energy (−1.34 eV), while the dissociation energy barrier of H 2 O is relatively low, causing the most likely occurrence of HER. This work provides sufficient space for the synthesis of ultra-small immiscible nano-alloy supported catalysts. The general-purpose ultra-small incompatible alloy RuRE-rGO NPs supported by carrier are synthesized by a one-step microwave reduction method with high yield and large-scale preparation, environmentally friendly, economical and low energy consumption, and exhibits excellent industrial-grade alkaline hydrogen evolution performance. [Display omitted] • The first synthesis of carrier-supported super-small incompatible alloy RuRE-rGO. • Solvent-free microwave reduction is simple, large-scale and environmentally friendly. • RuRE-rGO NPs have excellent electrocatalytic performance in alkaline HER. [ABSTRACT FROM AUTHOR]

Abstract: A total lightning data assimilation method was proposed and applied in a mesoscale convective system (MCS) simulation with the Weather Research and Forecasting (WRF) model. On the bases of analyses of several thunderstorm processes over northern China, empirical formulas between total lightning flash rate and ice-phase particle (graupel, ice, and snow) mixing ratio were constructed based on the well-known relationship between the occurrence of lightning activity and the content of ice-phase particles. The constructed nudging functions were added into the WSM6 microphysical scheme of WRF to adjust the mixing ratio of ice-phase particles within a temperature layer from 0°C to −20°C isotherms, and consequently the convective precipitation. The method was examined in a MCS with high lightning flash rate and heavy precipitation occurred over two megacities of Beijing and Tianjin, northern China. The representation of convection was significantly improved 1h after the lightning data assimilation, and even during the assimilation period. The precipitation center, amount and coverage were all much closer to the observation in the sensitivity run with lightning data assimilation than in the control run without lightning data assimilation. The results showed promising improvements on the convection and precipitation and demonstrated rationality and effectiveness of the proposed assimilation technique. The results also showed that active lightning regions have a strong capability of adjusting convection and precipitation, suggesting that the assimilation method can be used for improving the short-term precipitation forecasting of MCS with high, even moderate lightning flash rate. [Copyright &y& Elsevier]

• First metabolic profiling of chondrosarcoma SW-1353 cells. • Optimized pretreatment protocols for chondrosarcoma cell metabolite profiling. • Representative metabolites were quantitatively determined. • Simple, robust, and reproducible GC–MS method. • Helpful to further pathophysiology research of chondrosarcoma by metabolomics. Chondrosarcoma is the 2nd most frequent bone sarcoma. In this study, the metabolic profiling of human chondrosarcoma SW-1353 cell line was investigated for the first time. To obtain more precise information about the metabolites from chondrosarcoma cells, pretreatment methods including washing steps/solvents, harvesting conditions, and extraction protocols for chondrosarcoma SW-1353 cells were evaluated in the context of metabolite profiling by GC–MS technique. In addition, a total of 32 representative metabolites (related to amino acid metabolism, TCA cycle, glycolysis, and fatty acid metabolism) were quantitatively determined. We found that a fast water rinse step before metabolic quenching, may reduce the contaminants and improve sensitivity. Trypsin/ethylene diamine tetraacetic acid treatment led to a large amount of metabolite leakage, which was not suitable for metabolomics research. Methanol was selected as a more suitable extraction solvent among four extraction approaches applied to SW-1353 cells. The final protocol can provide a simple, robust, and reproducible method to obtain precise information about the metabolites from chondrosarcoma cells, which is helpful to further understand the chondrosarcoma cell physiology and the mechanism of drug resistance in this disease, from the perspective of metabolomics. [ABSTRACT FROM AUTHOR]

Based on 18 years of lightning data from 1996 to 2013 detected by optical transient detector (OTD) and lightning imaging sensor (LIS), the variation trend of lightning flash density (LFD) in the tropics and subtropics are investigated. Meteorological parameters from observational and reanalysis datasets are analyzed to understand the causes of LFD trends. The averaged LFD shows no significant trend during the period of analysis in the tropics and subtropics, while the regional LFD trends are significant. LFDs show significant negative linear trends in southeast North America (SENA), central South America (CSA) and eastern Australia (EA), with trend values of −0.26 fl km−2 year−1, −0.17 fl km−2 year−1, and − 0.14 fl km−2 year−1, respectively. At the same time, LFDs increased significantly in northwest South Asia (NWSA), with a trend of 0.24 fl km−2 year−1. Using a multiple linear regression method, the possible causes of LFD trends over these regions are investigated. The negative linear trends in SENA, CSA and EA are more likely due to the decreases of the convective available potential energy (CAPE), which may contribute −0.13 fl km−2 year−1, −0.14 fl km−2 year−1, and − 0.11 fl km−2 year−1 to the LFD trends in these regions, respectively. Increase of aerosol optical depth (AOD) exerts more influence on the increasing of LFD in NWSA, and could explain 0.08 fl km−2 year−1 of the LFD trends. • Lightning decreases significantly in SENA, CSA and EA, and increases significantly in NWSA. • Lightning trends in SENA, CSA and EA are mostly related to changes in CAPE. • Enhanced lightning activities in NWSA are mostly related to the increase of atmospheric aerosol loading. [ABSTRACT FROM AUTHOR]

PdPb nanosponges exhibit the high activity and selectivity for nitrogen reduction reaction electrocatalysis in 0.1 M HCl solution and the NH 3 yield reached 25.68 μg mg−1 cat h−1 (5.14 μg cm−2 h−1) at 0.05 V vs. RHE, corresponding Faraday efficiency was 5.79 %. At the −0.05 V vs. RHE, the NH 3 yield reached the maximum, 37.68 μg mg−1 cat h−1 (7.54 μg cm−2 h−1). • The PdPb nanosponges catalyst material was synthesized for the first time and used for the NRR reaction. • After introducing Pb metal to Pd nanosponges, the NH3 yield reached 25.68 μg mg−1 cat h−1 at 0.05 V vs. RHE (FE 5.79%). • DFT shows that the Pb in PdPb nanosponges can promote the adsorption of N 2 , inhibit *H adsorption. • This strategy can also be applied to other materials such as RuO 2 mamomaterials. Electrochemical N 2 reduction reaction (NRR) under milder conditions has become more and more promising and attractive due to its simplicity, high energy conversion efficiency and no need for expensive agents. But the designed electrocatalysts at ambient conditions are insufficient in activity and Faraday efficiency (FE). Among these electrocatalysts, Pd-based materials are promising NRR electrocatalysts ascribed to they have nitrogen reduction activity at a low overpotential. However, poorly NH 3 yields and FEs of Pd-based nanomaterials are still significant problems. Herein we report PdPb nanosponges that perform effectively electroreduction of N 2 to NH 3 under ambient conditions. It was found Pb element can inhibit the hydrogen evolution reaction (HER) of Pd and enhance NRR performance. According to our experiment, in 0.1 M HCl, the NH 3 yield of PdPb/C was 25.68 μg mg−1 cat h−1 (5.14 μg cm−2 h−1) at 0.05 V vs. RHE, and corresponding FE was 5.79 %, which is one of the most active materials at 0.05 V vs. RHE among the currently reported literature. Further reducing the voltage to more negative (−0.05 V vs. RHE), the NH 3 yield increased to the highest value, 37.68 μg mg−1 cat h−1 (7.54 μg cm−2 h−1), 8 times better than Pd/C (4.8 μg mg−1 cat h−1). Moreover, this catalyst also shows a great stability after 10 h. Besides that, density functional theory (DFT) also corresponds to the experimental results. The introduction of Pb can effectively reduce *H adsorption, inhibit HER, decrease the *NNH generation free energy of NRR process and improve NRR activity. Surprisingly, our ideas can also be extended to other materials such as RuO 2. It provides an excellent channel for the rational design of high-efficiency NRR electrocatalysts at ambient conditions in the future. [ABSTRACT FROM AUTHOR]

The experimentally known split (3 + 2) five‐electron donor bicyclo[3.2.1]octa‐2,6‐dien‐4‐yl (bcod) ligand provides a flexible alternative to the rigid planar cyclopentadienyl (Cp) ligand. In this connection, the structures and energetics of the binuclear iron carbonyl complexes (bcod)2Fe2(CO)n (n = 4, 3, 2, 1) have been investigated by density functional theory for comparison with the corresponding Cp2Fe2(CO)n derivatives. The cis and trans doubly CO‐bridged (bcod)2Fe2(μ‐CO)2(CO)2 structures are the lowest energy tetracarbonyl structures, similar to the Cp2Fe2(CO)4 system. However, an unbridged (bcod)2Fe2(CO)4 isomer lies only ~1 kcal/mol in energy above the doubly bridged isomers. The flexibility of the bcod ligand leads to low‐energy singlet and triplet spin state structures with agostic hydrogen atoms for the unsaturated (bcod)2Fe2(CO)n (n = 3, 2, 1) systems. Analogous structures are not found in the corresponding Cp2Fe2(CO)n systems with the rigid Cp ligand. Such structures, effectively involving donation of an electron pair from an olefinic C‐H bond to an iron atom through three‐center two‐electron C‐H‐Fe bonding, are energetically competitive with isomeric structures with metal‐metal multiple bonds. [ABSTRACT FROM AUTHOR]