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The multi-directional forging process can achieve large plastic deformation, and has great application prospects in industrial production. The Mg-9.55Gd-3.28Y-1.77Zn-0.34Zr (wt%) alloy containing LPSO phase was deformed in different passes and then quenched immediately by the multi-directional forging process with decreasing temperature, and the microstructure and mechanical properties of the alloy were analyzed. It is found that as the number of deformation passes increases, the coarse grains decrease, and the dynamic recrystallization fraction increases. The dynamic recrystallization grains swallow the original grains, promote the continuous refinement of the grains, and greatly improve the uniformity of the microstructure. At the same time, the maximum texture intensity of the (0001) basal plane is significantly reduced, and the pole figure distribution is more dispersed, which is attributed to the random orientation of dynamic recrystallization. Due to the refinement of the microstructure and the weakening of the texture, the tensile strength and yield strength at room temperature increase significantly. After 3 passes of deformation, the alloy has the highest mechanical properties, with tensile strength, yield strength, and elongation reaching 317 MPa, 233 MPa, and 15%, respectively.

The spiral fluidity sample was poured by the liquid of Ti-45Al-8Nb-0.2W-0.25Cr alloy. The flow cessation mechanism of TiAl based alloys was investigated, and its model was built through the observation on the macrostructure of TiAl based alloys formed in the channel. The results showed that the morphology and size of the columnar crystal and equiaxial crystal changed a lot with the increase of flow length. The flow cessation mechanism of the alloy is the abundant growth of columnar crystal in the root, which causes to form the structure and finally give rise to the “necking” leading to flow cessation.

As green solvents, ionic liquids (ILs) are quite suitable for the absorption of volatile organic compounds (VOCs) such as benzene and its homologues. However, solvent selection is the key to the VOC absorption process. In the present study, a rapid solvent screening tool, Conductor-like Screening Model for Real Solvents (COSMO-RS), was used to predict the solubility of toluene in 816 ILs. The effects of four structure characters, namely, the type and alkyl chain length of the cations and anions on the solubility of toluene were discussed. The following conclusions were drawn from the results: (1) ILs with pyrrolidinium-based cations showed better solubility than pyridinium- and imidazolium-based ones. (2) The solubility of toluene in PF6-based ILs increased with the increasing alkyl chain length, while its solubility in Ac-based ILs exhibited the opposite trend. (3) Toluene showed greater solubility in Cl-based ILs than those based on other anions. (4) The solubility of toluene increased with the anion alkyl chain length. Ac-based ILs were chosen as the most promising potential solvents, and further studied to determine the relationship between various interaction energy parameters and toluene solubility. The results showed that the misfit energy played a dominant role during the absorption process. Furthermore, several ILs were selected for experimental verification of the predicted solubility behavior using liquid and gaseous toluene. The results demonstrated that COSMO-RS could be used to semi-quantitatively and qualitatively predict the solubility of toluene, and this model had promising prospects in screening ILs for VOCs absorption. In summary, this study provided a fundamental basis and practical data for the control and treatment of VOCs.

We describe the discovery of histone deacetylase (HDACs) 1, 2, and 3 inhibitors with ethyl ketone as the zinc-binding group. These HDACs 1, 2, and 3 inhibitors have good enzymatic and cellular activity. Their serum shift in cellular potency has been minimized, and selectivity against hERG has been improved. They are also highly selective over HDACs 6 and 8. These inhibitors contain a variety of substituted heterocycles on the imidazole or oxazole scaffold. Compounds 31 and 48 stand out due to their good potency, high selectivity over HDACs 6 and 8, reduced hERG activity, optimized serum shift in cellular potency, and good rat and dog PK profiles.

This work indicates two novel ocean current observation methods that based on a glider type mobile platform. Glider with current meters are ideal current observation solutions for marine scientists since they have merits of large dynamic area and low power consumption, but their measurement accuracy is insufficient now. The proposed 1st solution, single point current meter compensated inversion method (SPCMCIM), is a revolution of the conventional inverse method by solving the acoustic Doppler to current profiler (AD2CP) induced turbulence problem. It’s a cooperated AD2CP and single point current meter (SPCM) algorithm that compensates the contaminated first AD2CP layer data. The physical position of the SPCM is also optimized according to a finite element analysis (FEA) study to minimize the interference generated by the SPCM. The 2nd method is solving the area restriction problems that AD2CP can just apply to non-pure water environment namely single point and inertial measurement inversion method (SPIMIM). It utilizes the SPCM as the only current observation source and takes advantages of physical properties of ocean currents. The currents are constitute of stable layers and each of them has a stable velocity, so the glider’s velocity variation can be obtained by reading the SPCM. The velocity variation in the transition process between layers can be acquired by the low cost inertial sensors. Finally, these theoretical studies were verified in an onsite sea trial. The SPCM and AD2CP was mounted to an underwater glider to measure the currents and a ship equipped AD2CP was used to provide the arbitrary data. Both of the proposed method can effectively measure the current velocity and induced significant enhancement than the classical inversion method. In particular, the first method conducted improvement of 70% accuracy by average. The 2nd one also shows an obvious improvement and has the advantage to deploy to high purity water area like deep lakes or north pole.

Variation in canopy water content (CWC) that can be detected from microwave remote sensing of vegetation optical depth (VOD) has been proposed as an important measure of vegetation water stress. However, the contribution of leaf surface water (LWs ), arising from dew formation and rainfall interception, to CWC is largely unknown, particularly in tropical forests and other high-humidity ecosystems. We compared VOD data from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E) and CWC predicted by a plant hydrodynamics model at four tropical sites in Brazil spanning a rainfall gradient. We assessed how LWs influenced the relationship between VOD and CWC. The analysis indicates that while CWC is strongly correlated with VOD (R2 = 0.62 across all sites), LWs accounts for 61-76% of the diurnal variation in CWC despite being < 10% of CWC. Ignoring LWs weakens the near-linear relationship between CWC and VOD and reduces the consistency in diurnal variation. The contribution of LWs to CWC variation, however, decreases at longer, seasonal to inter-annual, time scales. Our results demonstrate that diurnal patterns of dew formation and rainfall interception can be an important driver of diurnal variation in CWC and VOD over tropical ecosystems and therefore should be accounted for when inferring plant diurnal water stress from VOD measurements.

The aromatic C–H bond etherification with alcohols is one of the most atom-efficient ways to construct aryl ethers. However, it often requires a large excess of alcohols as etherification reagents,...

Exploring high-performance and low-cost bifunctional electrocatalysts is crucial for developing highly efficient overall water splitting cells. In this work, a facile and cheap co-precipitation method, which is compatible with large-scale production, is applied to prepare amorphous Fe-doped CoWO4 bifunctional electrocatalysts. Low overpotentials of 259 and 118 mV to reach a current density of 10 mA cm−2 for the OER and HER in 1 M KOH are found, respectively. Moreover, no detectable potential decay is observed at 50 mA cm−2 for at least 15 h, revealing its excellent long-term stability. Finally, a highly efficient overall water splitting cell is assembled with amorphous Fe-doped CoWO4 as a bifunctional electrocatalyst. A low cell voltage of 1.55 V is required to achieve a current density of 10 mA cm−2, which surpasses the benchmark IrO2‖Pt/C cell.

The construction of artificial photosynthetic (AP) systems for the hydrogen evolution reaction (HER) and carbon dioxide reduction reaction (CRR) is one of the hottest topics in the field of energy and sustainability. A typical AP system is composed of three key components, a photosensitizer (PS) for visible light harvesting, a catalyst for redox reactions, and a sacrificial electron donor (SED) for consuming holes generated in the PS. Among these three components, the PS and catalyst affect the photocatalytic performance much. There are two main types of AP systems, heterogeneous systems using inorganic materials and homogeneous systems using molecules. In addition to these, a compromise strategy of using inorganic luminescent nanoparticles as photosensitizers and molecular metal complexes as catalysts to construct hybrid AP systems has been developed. Inorganic luminescent nanoparticles, such as colloidal quantum dots (QDs) and carbon quantum dots (CQDs), have advantages of robust photostability, multiple excitation, and easy preparation. Molecular catalysts feature high activity, modifiable structures, and atom economy. Research on the combination of these two different types of materials to construct hybrid systems for solar fuel production is blooming. In the last decade, a large number of hybrid AP systems have been reported, and various strategies for system construction were developed. Obvious improvements in the photocatalytic efficiency of solar fuel production were witnessed. This review focuses on hybrid AP systems for the HER and CRR. The mechanism, composition, system design, and photocatalytic performances of the reported hybrid AP systems are reviewed. The advances and challenges in this field are discussed.

In temperate forests, autumn leaf phenology signals the end of leaf growing season and shows large variability across tree-crowns, which importantly mediates photosynthetic seasonality, hydrological regulation, and nutrient cycling of forest ecosystems. However, critical challenges remain with the monitoring of autumn leaf phenology at the tree-crown scale due to the lack of spatially explicit information for individual tree-crowns and high (spatial and temporal) resolution observations with nadir view. Recent availability of the PlanetScope constellation with a 3 m spatial resolution and near-daily nadir view coverage might help address these observational challenges, but remains underexplored. Here we developed an integration of PlanetScope with drone observations for improved monitoring of crown-scale autumn leaf phenology in a temperate forest in Northeast China. This integration includes: 1) visual identification of individual tree-crowns (and species) from drone observations; 2) extraction of time series of PlanetScope vegetation indices (VIs) for each identified tree-crown; 3) derivation of three metrics of autumn leaf phenology from the extracted VI time series, including the start of fall (SOF), middle of fall (MOF), and end of fall (EOF); and 4) accuracy assessments of the PlanetScope-derived phenology metrics with reference from local phenocams. Our results show that (1) the PlanetScope-drone integration captures large inter-crown phenological variations, with a range of 28 days, 25 days, and 30 days for SOF, MOF, and EOF, respectively, (2) the extracted crown-level phenology metrics strongly agree with those derived from local phenocams, with a root-mean-square-error (RMSE) of 4.1 days, 3.0 days and 5.4 days for SOF, MOF, and EOF, respectively, and (3) PlanetScope maps large variations in autumn leaf phenology over the entire forest landscape with spatially explicit information. These results demonstrate the ability of our proposed method in monitoring the large spatial heterogeneity of crown-scale autumn leaf phenology in the temperate forest, suggesting the potential of using high-resolution satellites to advance crown-scale phenology studies over large geographical areas.

Ionic hydrogels are promising candidates for fabricating stretchable electronics, but the deficiency in drying and freezing tolerances severely limits their application. Here, we report a facile and versatile salt-percolated strategy to fabricate hydrogels with exceptional freezing and drying tolerances, high conductivity, and anti-swelling ability for sensitive temperature and strain detection within a broad temperature range. We discovered that lithium bromide (LiBr) was the most effective drying and freezing inhibitor for hydrogels among the various salts. The 50 wt% LiBr-percolated hydrogels retained ultrahigh stretchability (625% strain) and conductivity even at −78.5 °C or in ambient air for a year. The important role of LiBr in inhibiting the drying and freezing of hydrogels was understood using density functional theory (DFT) simulations on a molecular scale, revealing the formation of stable Li+–H2O and Br−–H2O clusters. It was found that the introduction of LiBr enhanced the temperature and strain sensing performance, e.g., the stability and working temperature range. Multifunctional transparent sensors exhibited a high thermal sensitivity (2.54%/°C), broad temperature detection range (−78.5 to 97 °C), low detection limit (0.1% strain), and low hysteresis and baseline drift in cycling strain sensing. Attributed to the high tolerance of hydrogels to a wide range of temperatures, the strain sensing ability was maintained even at −20 °C. Various physiological signals, such as facial expressions, word pronunciation and knee bending, are real-time monitored using hydrogel-based epidermal sensors.

Alzheimer’s disease (AD) is a chronic neurodegenerative disease. Better imaging and early diagnosis of biomarkers of AD is extremely important for therapeutic interventions. The amyloid cascade hypothesis and its revised version identify insoluble β-amyloid deposition as a good diagnostic biomarker for AD. Moreover, lipid droplets may also act as an auxiliary biomarker related to AD pathology based on recent studies. Herein, two quinoline-based AIE probes were designed and synthesized for the imaging of Aβ plaques and lipid droplets. The probes exhibited remarkable turn-on fluorescence enhancements with the Aβ aggregates. The lipid droplets-targeting probe FB exhibited high selectivity and binding affinity towards the Aβ aggregates with a detection limit as low as 26.9 nM. Furthermore, FB was capable of readily imaging Aβ plaques and lipid droplets at the cellular level and in brain sections of transgenic AD mice. The probe FB can serve as a promising tool for developing early diagnosis and innovative therapeutics of AD.

The contamination of surface water by pharmaceuticals and personal care products (PPCPs) has attracted widespread attention, but data regarding their impacts on groundwater (GW) are sparse. In river–GW interaction areas, rivers are likely an important source of PPCPs in aquifers, especially rivers impacted by sewage treatment plant effluent. Understanding the characterization, transport, and risk is valuable for the effective protection of vital aquatic ecosystem services, environmental health, and drinking water supplies. To attain this objective, statistics with spatial analysis and ecological risk were used to assess the effects of artificial recharge (AR) engineering on 16 PPCPs in aquifers in North China. The results indicated that 15 PPCPs were detected in unconfined and confined aquifers, with a few PPCPs being detected up to 1,000 ng/L. The most frequently detected PPCPs were sulfisoxazole, sulfachloropyridazine, sulfamerazine, sulfamethazine, sulfamethoxazole, and ibuprofen. In addition, the spatial and seasonal variations in most PPCPs were significant. Furthermore, the maximum concentrations were compared to the predicted no-effect concentrations to evaluate the ecological risk, and four PPCPs were found to be of medium or high ecological risk. This study highlights that AR engineering has a significant ecological effect on GW.

3D bioprinting is one of the rapidly evolving fields of tissue engineering where microengineering meets cells biology within an unprecedented precision to construct tissue structures of various forms with complexity. However, enabling simultaneous printing of heterogeneous biomaterial along with scaffold components through the currently available printers is still considered as a major challenge due to the lack of instrumentation. Flow control is one of the major issues associated with the process. In this aspect, a microfluidic nozzle head equipped with two shape-memory alloy (SMA) actuators was proposed and integrated with a commercially available 3D printer to assist the biomaterial printing in a more systematic manner. The SMA actuator restrains the amount of flows for fabricating the desired scaffold components. Experimental results illustrated that the use of SMA actuator ensued a rapid and precise flow control of biomaterial and can further facilitate to maintain the width of any printed structures. As a proof of concept for the profound biomedical applications with the present manufacturing configuration, a 3D printed hydrogel platform was fabricated with demonstrated characters for later cell seeding after the printing further opens a new chapter in terms of biomaterial printing.

The geometric, electronic and optical properties of SrCO3 under pressure up to 20 GPa are studied based on the density functional theory. The optimised structure parameters are in good agreement wi...

Simultaneous enhancement in water flux and removal efficiency during the filtration process remains a big challenge for separation membranes. The porous structure of the filter paper can provide many channels for water transportation, but the separation performance is generally poor. The purpose of this study is to develop a new kind of filter paper consisting of ultralong hydroxyapatite (HAP) nanowires, cellulose fibers (CFs) and double metal oxide (LDO) nanosheets, and to achieve the simultaneous enhancement of both water flux and removal efficiency for high-performance dye separation. In this work, a novel kind of LDO/HAP/CF nanocomposite filter paper consisting of ultralong HAP nanowires and CFs and LDO nanosheets has been developed for rapid water filtration and highly efficient dye adsorption. Positively charged LDO nanosheets can adsorb on the surface of negatively charged ultralong HAP nanowires and embed in the porous networked structure of the LDO/HAP/CF nanocomposite filter paper, which can provide a porous structure for rapid water transportation and can adjust the pore size of the nanocomposite filter paper. As a result, the pure water flux of the LDO/HAP/CF nanocomposite filter paper can be adjusted. The optimized pure water flux of the LDO/HAP/CF nanocomposite filter paper can reach 783.6 L m-2 h-1 bar-1, which is 1.51 times that of the HAP/CF filter paper without LDO nanosheets (518.6 L m-2 h-1 bar-1). More importantly, the adsorption capacity of LDO nanosheets is high for dye molecules, the rejection percentage of Congo red (CR) by the as-prepared HAP/CF filter paper is only 59.8%, and its water flux is 534.7 L m-2 h-1 bar-1. The optimized rejection percentage and water flux of the LDO/HAP/CF nanocomposite filter paper for CR are significantly enhanced (98.3% and 736.8 L m-2 h-1 bar-1, respectively) compared to those of the HAP/CF filter paper. The size of LDO nanosheets has a significant effect on the water flux and dye rejection percentage of the LDO/HAP/CF nanocomposite filter paper. The as-prepared LDO/HAP/CF nanocomposite filter paper is promising for the applications in highly efficient purification of wastewater containing dye molecules.

Terrestrial laser scanning (TLS) has been recognized as an accurate means for non-destructively deriving three-dimensional (3D) forest structural attributes. These attributes include but are not limited to tree height, diameter at breast height, and leaf area density. As such, TLS has become an increasingly important technique in forest inventory practices and forest ecosystem studies. Multiple TLS scans collected at different locations are often involved for a comprehensive characterization of 3D canopy structure of a forest stand. Among which, multi-scan registration is a critical prerequisite. Currently, multi-scan TLS registration in forests is mainly based on a very time-consuming and tedious process of setting up hand-crafted registration targets in the field and manually identifying the common targets between scans from the collected data. In this study, a novel marker-free method that automatically registers multi-scan TLS data is presented. The main principle underlying our method is to identify shaded areas from the raw point cloud of a single TLS scan and to use them as the key features to register multi-scan TLS data. The proposed method is tested with 17 pairs of TLS scans collected in six plots across China with various vegetation characteristics (e.g., vegetation type, height, and understory complexity). Our results showed that the proposed method successfully registered all 17 pairs of TLS scans with equivalent accuracy to the manual registration approach. Moreover, the proposed method eliminates the process of setting up registration targets in the field, manually identifying registration targets from TLS data, and processing raw TLS data to extract individual tree attributes, which brings it the advantages of high efficiency and robustness. It is anticipated that the proposed algorithms can save time and cost of collecting TLS data in forests, and therefore improves the efficiency of TLS forestry applications.

Based on thin-section, argon-ion polished large-area imaging and nano-CT scanning data, the reservoir characteristics and genetic mechanisms of the Lower Silurian Longmaxi shale layers with different laminae and laminae combinations in the Sichuan Basin were examined. It is found that the shale has two kinds of laminae, clayey lamina and silty lamina, which are different in single lamina thickness, composition, pore type and structure, plane porosity and pore size distribution. The clayey laminae are about 100 μm thick each, over 15% in organic matter content, over 70% in quartz content, and higher in organic pore ratio and plane porosity. They have abundant bedding fractures and organic matter and organic pores connecting with each other to form a network. In contrast, the silty laminae are about 50 μm thick each, 5% to 15% in organic matter content, over 50% in carbonate content, higher in inorganic pore ratio, undeveloped in bedding fracture, and have organic matter and organic pores disconnected from each other. The formation of mud lamina and silt lamina may be related to the flourish of silicon-rich organisms. The mud lamina is formed during the intermittent period, and silt lamina is formed during the bloom period of silicon-rich organisms. The mud laminae and silt laminae can combine into three types of assemblages: strip-shaped silt, gradating sand-mud and sand-mud thin interlayers. The strip-shaped silt assemblage has the highest porosity and horizontal/vertical permeability ratio, followed by the gradating sand-mud assemblage and sand-mud thin interlayer assemblage. The difference in the content ratio of the mud laminae to silt laminae results in the difference in the horizontal/vertical permeability ratio.

A series of graphene nanosheet (GNS) supported nickel-molybdenum nanomaterials with controllable phases and compositions were synthesized for the hydrogen evolution reaction (HER) in both acidic and alkaline solutions. Experimental results indicate that the Ni-Mo2C/GNS catalysts show superior activity in 0.5 M H2SO4 owing to the presence of abundant heterogeneous interfaces. Notably, the 1Ni-0.5Mo2C/GNS possesses an apparent current density of 10 mA cm−2 at an overpotential of 49.6 mV and a turnover frequency (TOF) value of 0.86 s−1 at an overpotential of 200 mV. Such remarkable activity renders the 1Ni-0.5Mo2C/GNS to be one of the best non-precious HER electrocatalysts in acidic electrolytes reported in the literature. In contrast, the Ni4Mo/GNS catalyst exhibits better activity in 1 M KOH solution due to the formation of Ni4Mo alloy. It yields a current density of 10 mA cm−2 at an overpotential of 69 mV and TOF value of 0.11 s−1 at an overpotential of 100 mV. Density functional theory calculations indicate that the superior activity of the Ni-Mo2C/GNS in acidic solutions is related to the appropriate hydrogen adsorption free energy, which is highly beneficial for the Tafel step. However, the leaching of nickel from the catalysts was noted in 0.5 M H2SO4, thus leading to unsatisfactory durability. The better activity of the Ni4Mo/GNS in alkaline solutions was attributed to the low energy barrier of water activation on Ni4Mo alloy surface, which facilitates the dissociation of water molecules. The electrocatalysts showed enhanced durability in alkaline electrolytes. These findings from this work are valuable for the further exploration of advanced Ni-Mo based HER electrocatalysts.

One of the critical issues for electret/triboelectric devices is the poor charge viability and stability in humid environments. Herein, we propose a new origami-inspired “W-tube”-shaped triboelectric nanogenerator (W-TENG) with two thin-film electrets folded based on Miura-origami. The Miura-origami fold is capable of transforming flat materials with large surface areas into reduced and compressed complex 3D structures with parallelogram tessellations. The triboelectric power generation components can thus be hermetically sealed inside the “W-tube” to avoid contact with the external humid environment. Furthermore, the elastic nature of the Miura-origami fold endows the proposed W-TENG device with excellent deformability, flexibility, and stretchability. Therefore, it is capable of harvesting kinetic energy from various directions and forms of movement, including horizontal pressing, vertical tapping, and lateral bending. The compact, light weight, and self-rebounding properties of the origami structure also make it convenient for integration into wearable devices. Various parameters of the W-TENG are intensively investigated, including the number of power generation units, original height of the device, acceleration magnitude, excitation direction, and water-proof capability. Triggered by hand tapping impulse excitation in the horizontal and vertical directions, the instantaneous open-circuit voltages can reach 791 V and 116 V with remarkable optimum powers of 691 μW at 50 MΩ and 220 μW at 35 MΩ, respectively. The outcomes of this work demonstrate the fusion of the ancient art of origami, material science, and energy conversion techniques to realize flexible, multifunctional, and water-proof TENG devices. Researchers have used techniques from origami to engineer a flexible, resilient, water-proof power generator, which can be used with wearable devices. The device, designed by a team led by Kai Tao of China’s Northwestern Polytechnical University, consists of two thin films of dielectric material, which can generate power when deformed. This structure is then folded in a Miura fold, a pattern which compresses a large surface area into a smaller area. The resulting spring-like makes the device return to its original shape after deformation while also offering compactness and flexibility together. The device generated power when tapped or bent, and the origami structure hermetically sealed the components, making the generator water-proof. With this combination of origami and material science, researchers can design and build flexible energy-harvesting devices to power wearable devices or other flexible electronics.

Low-molecular-weight organic acids (LMWOAs), a type of small organic molecules with one or more carboxyl groups present in soil, play an important role in the soil ecosystem. Greenhouse soil could ...

This paper proposes a novel fast deterministic quaternion attitude determination method for accelerometer and magnetometer combination (AMC). After taking insight to the attitude determination theory, an important relationship between the sensor outputs and the magnetometer’s reference vector is successfully derived. Based on the relationship, the optimal quaternion associated with the attitude of a certain object is easily calculated. The main breakthrough of this paper is that it significantly simplifies the determination of the magnetometer’s reference vector which always needs systematic calibration or iterative estimation in existing methods. We name the proposed method the Fast Accelerometer-Magnetometer Fusion (FAMF). Our proposed method has the advantages of better computation accuracy and less time consumption. Several experiments are carried out to illustrate the attitude determination results. Besides, comparisons with existing representative methods are also presented in the experimental section of this paper, which verify the effectiveness of the proposed FAMF. Finally, we experimentally show that the FAMF’s roll and pitch angles are immune to magnetic distortion, which ensures the robustness under complex environments for micro air vehicles (MAV).

Three cationic capsule-shaped Zr-based metal-organic polyhedra (MOPs) with different cavity sizes were successfully constructed through the self-assembly of trinuclear zirconocene clusters and imidazolium-functionalized dicarboxylic ligands. Owing to the imidazolium groups in the MOPs, they show good CO2 adsorption uptake. Moreover, the halogen anions of the imidazolium groups and Bronsted acid sites (-OH) in the Zr-based knots are in close proximity, making these MOPs able to catalyze synergistically the cycloaddition reaction of CO2 with epoxides into cyclic carbonates. This is the first report of using MOPs as catalysts for this reaction without the addition of a cocatalyst.

The S ugars W ill E ventually be E xported T ransporter (SWEET) gene family, identified as sugar transporters, has been demonstrated to play key roles in phloem loading, grain filling, pollen nutrition, and plant-pathogen interactions. To date, the study of SWEET genes in response to abiotic stress is very limited. In this study, we performed a genome-wide identification of the SWEET gene family in wheat and examined their expression profiles under mutiple abiotic stresses. We identified a total of 105 wheat SWEET genes, and phylogenic analysis revealed that they fall into five clades, with clade V specific to wheat and its closely related species. Of the 105 wheat SWEET genes, 59% exhibited significant expression changes after stress treatments, including drought, heat, heat combined with drought, and salt stresses, and more up-regulated genes were found in response to drought and salt stresses. Further hierarchical clustering analysis revealed that SWEET genes exhibited differential expression patterns in response to different stress treatments or in different wheat cultivars. Moreover, different phylogenetic clades also showed distinct response to abiotic stress treatments. Finally, we found that homoeologous SWEET genes from different wheat subgenomes exhibited differential expression patterns in response to different abiotic stress treatments. The genome-wide analysis revealed the great expansion of SWEET gene family in wheat and their wide participation in abiotic stress response. The expression partitioning of SWEET homoeologs under abiotic stress conditions may confer greater flexibility for hexaploid wheat to adapt to ever changing environments.

The shales in the 2nd Member of Shanxi Formation in the east margin of the Ordos Basin were deposited in a marine-nonmarine transitional environment during the Permian. Based on the recent breakthroughs in the shale gas exploration and theoretical understandings on the shale gas of the study area, with a comparison to marine shale gas in the Sichuan Basin and marine-nonmarine transitional shale gas in the U.S., this study presents the geological characteristics and development potential of marine-nonmarine transitional gas in the study area. Four geological features are identified in the 2nd Member of the Shanxi Formation in the study area has: (1) stable sedimentary environment is conductive to deposition of widely distributed organic shale; (2) well-developed micro- and nano- scale pore and fracture systems, providing good storage capacity; (3) high content of brittle minerals such as quartz, leading to effectively reservoir fracturing; and (4) moderate reservoir pressure and relatively high gas content, allowing efficient development of shale gas. The 2nd Member of Shanxi Formation in the east margin of Ordos Basin is rich in shale gas resource. Three favorable zones, Yulin-Linxian, Shiloubei-Daning-Jixian, and Hancheng-Huangling are developed, with a total area of 1.28×104 km2 and resources between 1.8×1012 and 2.9×1012 m3, indicating a huge exploration potential. Tests of the 2nd Member of Shanxi Formation in vertical wells show that the favorable intervals have stable gas production and high reserves controlled by single well, good recoverability and fracability. This shale interval has sufficient energy, stable production capacity, and good development prospects, as evidenced by systematic well testing. The east margin of the Ordos Basin has several shale intervals in the Shanxi and Taiyuan formations, and several coal seams interbedded, so collaborative production of different types of natural gas in different intervals can be considered. The study results can provide reference for shale gas exploration and development and promote the rapid exploitation of shale gas in China.

Severe plastic deformation can be produced by repetitive upsetting-extrusion process. Using the repetitive upsetting-extrusion (RUE) process at decreasing temperature, the Mg-12.0Gd-4.5Y-2.0Zn-0.4Zr (wt %) alloy was deformed by different RUE passes and then heat treated. The microstructure, texture and mechanical properties of the alloy were compared and analyzed. The results demonstrate that with the increase of deformation passes, the coarse grains of the alloy decreased, the dynamic recrystallization fraction increased, and the dynamic recrystallized grains phagocytized the original grains. This can promote the continuous refinement of the grains and the microstructure uniformity. The maximum texture intensity of the (0001) basal plane decreased significantly with the increase of processing passes and the dispersion degree of pole figure increased. The orientation of dynamic recrystallized grains was randomly distributed to weaken texture. Due to the refinement of microstructure and the weakening of texture, the tensile strength and yield strength of the alloy obviously increased at room temperature. The mechanical properties of the alloy reached the highest after 3 passes and heat treatment.

To address the low gas sensitivity of pristine graphene (Gr), chemical modification of Gr has been proved as a promising route. However, the existing chemical functionalization method imposes the u...

From perspective of risk management and control, the ecological risk contributed from various sources can give direct risk information in selecting priority pollutants to control in river ecosystem restoration. However, studies combined receptor model with risk assessment to obtain ecological risk in every source category that is still limited. It is essential to quantitatively and spatially analyse the contributions of various sources to both the content and ecological risk in river system. Ten trace metals in 47 sediment samples were collected in Le’an River, which is the main tributary of the largest freshwater lake in China, Poyang Lake and analysed by laboratory analysis. The potential ecological risk index (PERI) model was used to evaluate the ecological risk posed by sediment trace metals. The positive matrix factorization (PMF) was utilized to identify the source of sediment trace metal and apportion their contribution. The ecosystem risks of the sources were quantitatively analysed by combining PERI and PMF, termed PMF-PERI. In addition, we conducted a spatial dissimilarity analysis of the source contribution distributions. The ecological risk assessment results showed that the metals Cd, Cu, and Hg may cause the main ecological hazards. Source apportionment of the trace metal concentrations indicated that the dominant source of trace metals in the sediment was human activities (55.83%), such as Pb-Zn mining and agricultural activities (30.33%), gold smelting (13.62%) and copper mining (11.89%). Source apportionment of the ecological risks posed by the trace metals indicated that natural sources were the main ecosystem risk sources (64.75%), followed by Pb-Zn mining and agricultural activities (14.65%), copper mining (10.67%) and gold smelting (9.93%). The results of spatial dissimilarity analysis indicated that the significant spatial variation in the contribution compositions was related to the locations of the sources and the river. The results of this study indicated that the emission reduction of agricultural activities should be given priority attention for protecting the watershed environment of the Le’an River. In addition, this study extends the use of risk assessment in receptor model source apportionment.

The lack of efficient means to accurately infer photosynthetic traits constrains understanding global land carbon fluxes and improving photosynthetic pathways to increase crop yield. Here, we investigated whether a hyperspectral imaging camera mounted on a mobile platform could provide the capability to help resolve these challenges, focusing on three main approaches, that is, reflectance spectra‐, spectral indices‐, and numerical model inversions‐based partial least square regression (PLSR) to estimate photosynthetic traits from canopy hyperspectral reflectance for 11 tobacco cultivars. Results showed that PLSR with inputs of reflectance spectra or spectral indices yielded an R 2 of ~0.8 for predicting V cmax and J max, higher than an R 2 of ~0.6 provided by PLSR of numerical inversions. Compared with PLSR of reflectance spectra, PLSR with spectral indices exhibited a better performance for predicting V cmax (R 2 = 0.84 ± 0.02, RMSE = 33.8 ± 2.2 μmol m−2 s−1) while a similar performance for J max (R 2 = 0.80 ± 0.03, RMSE = 22.6 ± 1.6 μmol m−2 s−1). Further analysis on spectral resampling revealed that V cmax and J max could be predicted with ~10 spectral bands at a spectral resolution of less than 14.7 nm. These results have important implications for improving photosynthetic pathways and mapping of photosynthesis across scales., Photosynthetic capacities can be predicted with a R 2 of ~0.8 using plot‐level hyperspectral reflectance and partial least squares regression. About 10 spectral bands with the spectral resolution less than 14.7 nm are enough for accurately estimating photosynthetic capacities.

The thermal conductivity of two-dimensional materials like graphene can efficiently be tuned by introducing holes, in which the density and distribution of the holes are the key parameters. Furthermore, the distribution of holes can induce a variation as high as 74% in the thermal conductivity for porous graphene with a given density of holes. Therefore, an existing challenge is to find the optimal distribution of holes that can minimize or maximize the thermal conductivity of porous graphene as the design space expands dramatically with increasing hole density. We therefore apply an inverse design methodology based on machine learning to reveal the relationship between hole distribution and thermal conductivity reduction in monolayer graphene. The methodology reveals that holes that are randomly distributed transverse to the direction of heat flow, but that exhibit some periodicity along the direction of heat flow, represent the optimal distribution to minimizing the thermal conductivity for porous graphene. Lattice dynamics calculations and wave packet simulations reveal that this spatial distribution effectively causes localization of the phonon modes in porous graphene, which reduces the thermal conductivity. Overall, this work demonstrates the power of machine learning-based design approaches to efficiently obtain new physical insights for scientific problems of interest.

Purpose For fixed-wing micro air vehicles, the attitude determination is usually produced by the horizon/Global Navigation Satellite System (GNSS) in which the GNSS provides yaw estimates, while roll and pitch are computed using horizon sensors. However, the attitude determination has been independently obtained from the two sensors, which will result in insufficient usage of data. Also, when implementing attitude determination algorithms on embedded platforms, the computational resources are highly restricted. This paper aims to propose a computationally efficient linear Kalman filter to solve the problem. Design/methodology/approach The observation model is in the form of a least-square optimization composed by GNSS and horizontal measurements. Analytical quaternion solution along with its covariance is derived to significantly speed up on-chip computation. Findings The reconstructed attitude from Horizon/GNSS is integrated with quaternion kinematic equation from gyroscopic data that builds up a fast linear Kalman filter. The proposed filter does not involve coupling effects presented in existing works and will be more robust encountering bad GNSS measurements. Originality/value Electronic systems are designed on a real-world fixed-wing plane. Experiments are conducted on this platform that show comparisons on the accuracy and computation execution time of the proposed method and existing representatives. The results indicate that the proposed algorithm is accurate and much faster computation speed in studied scenarios.

A facile, one-step hydrothermal route was exploited to prepare SnO2-decorated reduced graphene oxide hydrogel (SnO2/RGOH) with three-dimensional (3D) porous structures for NO2 gas detection. Various material characterizations demonstrate the effective deoxygenation of graphene oxide and in situ growth of rutile SnO2 nanoparticles (NPs) on 3D RGOH. Compared with the pristine RGOH, the SnO2/RGOH displayed much lower limit of detection (LOD) and an order of magnitude higher sensitivity, revealing the distinct impact of SnO2 NPs in improving the NO2-sensing properties. An exceptional low theoretical LOD of 2.8 ppb was obtained at room temperature. The p-n heterojunction formed at the interface between RGOH and SnO2 facilitates the charge transfer, improving both the sensitivity in NO2 detection and the conductivity of hybrid material. Considering that existing SnO2/RGO-based NO2 sensors suffer from great vulnerability to humidity, here we employed integrated microheaters to effectively suppress the response to humidity, with nearly unimpaired response to NO2, which boosted the selectivity. Notably, a flexible NO2 sensor was constructed on a liquid crystal polymer substrate with endurance to mechanical deformation. This work indicates the feasibility of optimizing the gas-sensing performance of sensors by combining rational material hybridization, 3D structural engineering with temperature modulation.

An artificial photosynthetic assembly (APA) of a hollow-rod structure was successfully constructed by using synthetic building blocks to mimic the structure and function of natural photosynthetic bacteria. The APA was formed by the incorporation of carbon nanoparticles as light harvesters into an enzyme-like polymer, PEI-Co, containing cobalt complexes as redox catalytic centres. The APA features a bacteria-like shape of ca. 2–3 μm length rods and a hollow structure positioning photosynthetic components at the surface. The APA integrates key components, the light harvester, redox catalyst, and proton relay group, of photosynthetic systems in assemblies formed from a polymeric framework. The APA system in aqueous solution converts protons to H2 under visible light irradiation with obvious advantages. It exhibits a 50-fold improvement in hydrogen production activity and has a broader pH response of photocatalytic H2 production compared with a non-assembled system.

It has been proved that silicon-substituted calcium phosphate ceramics possess superior bone regeneration and resorbability to HA, while the synthesis of single-phase nanocrystallized high Si-containing calcium phosphate is still a challenge. In the present work, a novel and facile aqueous precipitation method assisted with ultrasonic irradiation was adopted firstly to synthesise a single-phase nanocrystallized calcium silicophosphate (Ca5(PO4)2SiO4, CPS) biomaterial. Crystallization and morphology of Si-apatite precursors synthesized with or without ultrasonic assistance were primarily investigated and the related mechanism was discussed. Moreover, the sinterability, in vitro bioactivity and osteogenic activity of the synthesized CPS were studied in detail. Results showed that an ultrasonic cavitation effect could be beneficial to form a highly dispersive CPS precursor with a single Si-apatite phase, which greatly reduced the calcination temperature of CPS from 1350 °C to 1000 °C. Nanocrystallized CPS powders were obtained successfully under ultrasound-assisted conditions, which showed superior sinterability, in vitro bioactivity and osteogenic activity than those of micron-sized CPS and HA powders. It might be a promising candidate material for bone tissue regeneration applications.

Li2CO3 is the cathodic discharge product of a Li-CO2/O2 battery and is difficult to electrochemically decompose. The accumulation of Li2CO3 leads to battery degradation and results in a short lifes...

Understanding the relationships between the vertical distribution of liverwort communities and associated environmental factors is vital for biodiversity conservation in karst sinkholes. The abunda...

A multifunctional sensor comprising humidity, temperature, and flow detection capabilities is fabricated with a facile, single-layered device structure. A microheater based on serpentine Pt microlines plays key roles in both humidity and flow sensing at the hot state by introducing an efficient Joule heating effect, and meanwhile functions as a reliable thermistor at the cold state for accurate temperature measurement. For the first time, the strong temperature-dependent humidity-sensing properties of graphene oxide (GO) are revealed using the microheater platform. The GO-based humidity sensor displays ultrahigh sensitivity [124/% relative humidity (RH)], fast response time (3 s), wide detection range (8-95% RH) at room temperature, while the sensitivity drops at elevated temperatures, indicating the non-negligible temperature effect. Interestingly, a linear relationship between sensitivity and voltage is observed for the flow sensor, indicating the capability to manipulate sensitivity by conveniently modifying the voltage applied on the microheater. Because the three sensors work independently with distinguishable output signals, multiparametric sensing is enabled to monitor various human activities, such as respiration, noncontact sensation, and so forth. This work develops a simple, cost-effective, and useful multiparametric-sensing platform using a microheater for potential applications in the growing fields of internet of things, healthcare monitoring, and human-machine interfaces.

Herein a versatile adsorbent has been synthesized by immobilization of ethylenediaminetetraacetic acid (EDTA) into the pores of the Zr-based metal organic framework (UiO-66) through a facile method. The as-prepared EDTA modified UiO-66 (UiO-66-EDTA) was characterized completely to investigate its physical and chemical properties. It shows great chemical stability with octahedral structure and carboxylic groups and amine groups. Through batch experiments, UiO-66-EDTA shows no specificity for the removal of diverse heavy metal ions (three categories: soft acids, hard acids, and borderline acids) because of its both hard and relatively softer chemical characters of functional groups. The maximum removal capacities of UiO-66-EDTA for Eu3+ (hard acids), Hg2+ (soft acids) and Pb2+ (borderline acids) are 195.2, 371.6 and 357.9 mg g−1, respectively. Notably, 11 metal ions removal efficiency reaches over 99% in co-existing system. The results from X-ray photoelectron spectroscopy (XPS) analysis reveal the coordination of Eu3+, Hg2+ and Pb2+ with carboxyl groups ( COOH) and tertiary amine groups (C N(C) C) is responsible for their removal by UiO-66-EDTA. Given the fact that UiO-66-EDTA possesses high chemical stability, facile synthesis method, efficient removal performance and superior reusability, it can be applied in treatment of seriously polluted water with multi-pollutants.

Lianas are found in virtually all tropical forests and have strong impacts on the forest carbon cycle by slowing tree growth, increasing tree mortality and arresting forest succession. In a few local studies, ecologists have successfully differentiated lianas from trees using various remote sensing platforms including satellite images. This demonstrates a potential to use remote sensing to investigate liana dynamics at spatio-temporal scales beyond what is currently possible with ground-based inventory censuses. However, why do liana-infested tree crowns and forest stands display distinct spectral signals? And is the spectral signal of lianas only locally unique or consistent across continental and global scales? Unfortunately, we are not yet able to answer these questions, and without such an understanding the limitations and caveats of large-scale application of automated classifiers cannot be understood. Here, we tackle the questions of why we can detect lianas from airborne and spaceborne remote sensing platforms. We identify whether a distinct spectral distribution exists for lianas, when compared to their tree hosts, at the leaf, canopy and stand scales in the solar spectrum (400 to 2500 nm). To do so, we compiled databases of (i) leaf reflectance spectra for over 4771 individual leaves of 539 species, (ii) fine-scale (∼1m2) surface reflectance from 999 tree canopies characterized by different levels of liana infestation in Panama and Malaysia, and (iii) coarse-scale (>100 m2) surface reflectance from hundreds of hectares of heavily infested liana forest stands in French Guiana and Bolivia. Using these data, we find consistent spectral signal of liana-infested canopies across sites with a mean inter-site correlation of 89% (range 74-94%). However, as we find no consistent difference between liana and tree leaves, a distinct liana spectral signal appears to only manifests at the canopy and stand scales (>1m2). To better understand this signal, we implement mechanistic radiative transfer models capable of modeling the vertically stratificatied non-linear mixing of spectral signals intrinsic to lianas infestation of forest canopies. Next, we inversely fit the models to observed spectral signals of lianas at all scales to identify key biochemical or biophysical processes. We then corroborate our model results with field data on liana leaf chemistry and canopy structural properties. Our results suggest that a liana-specific spectral distribution arises due to the combination of cheaply constructed leaves and efficient light interception. A model experiment revealed that the spectral distribution was most sensitive to lower leaf and water mass per unit area, affecting the absorption of NIR and SWIR radiation, and a more planophile (flatter) leaf angle distribution. Finally, we evaluate the theoretical discernibility of lianas from trees and how this varies with remote sensing platforms and resolution. We end by discussing the potential, limitations and risks of applying automated classifiers to detect lianas from remotely sensed data at large scales.

Groundwater is an important source of water in Beijing. Hydrochemical composition and water quality are the key factors to determine the availability of groundwater. Therefore, an improved integrated weight water quality index approach (IWQI) combining the entropy weight method and the stochastic simulation method is proposed. Through systematic investigation of groundwater chemical composition in different periods, using a hydrogeochemical diagram, multivariate statistics and spatial interpolation analysis, the spatial evolution characteristics and genetic mechanism of groundwater chemistry are discussed. The results show that the groundwater in the study area is weakly alkaline and low mineralized water. The south part of the study area showed higher concentrations of total dissolved solids, total hardness and NO3−-N in the dry season and wet season, and the main hydrochemical types are HCO3−-Ca and HCO3−-Ca-Mg. The natural source mechanism of the groundwater chemical components in Chaoyang District includes rock weathering, dissolution and cation exchange, while the human-made sources are mainly residents and industrial activities. Improved IWQI evaluation results indicate that water quality decreases from southwest to northeast along groundwater flow path. The water quality index (WQI) method cannot reflect the trend of groundwater. Sensitivity analysis indicated that the improved IWQI method could describe the overall water quality reliably, accurately and stably.

We report a small-angle ultra-narrowband mid-infrared tunable absorber that uses graphene and dielectric metamaterials. The absorption bandwidth of the absorber at the graphene Fermi level of 0.2 eV is 0.055 nm, and the absorption peaks can be tuned from 5.14803 to 5.1411 μm by changing the graphene Fermi level. Furthermore, the resonance absorption only occurs in the angle range of several degrees. The simulation field distributions show the magnetic resonance and Fabry–Pérot resonance at the resonance absorption peak. The one-dimensional photonic crystals (1DPCs) in this absorber act as a Bragg mirror to efficiently reflect the incidence light. The simulation results also show that the bandwidth can be further narrowed by increasing the resonance cavity length. As a tunable mid-infrared thermal source, this absorber can possess both high temporal coherence and near-collimated angle characteristics, thus providing it with potential applications.

In this paper, we propose a radio-over-fiber system with no filters and generate 80 and 160 GHz millimeter (mm) waves via two Mach–Zehnder modulators (MZMs). The two MZMs, biased at the maximum transmission point, are used to suppress odd-order sidebands. By controlling the phase difference between the RF driving signal of the two MZMs, the ± ( 4 n − 2 ) -order is canceled. By adjusting the optical attenuator and phase shifter, the 0-order sideband is canceled, so only the ± 4 n -order sidebands are left. The simulation results show that using a 10 GHz RF signal to drive the MZMs, we obtain an 80 GHz mm wave signal with a 36.59 dB optical sideband suppression ratio (OSSR), a 30.27 dB radio frequency sideband suppression ratio (RFSSR), and a 160 GHz mm wave signal with a 30.34 dB OSSR and 24.77 dB RFSSR. The results are consistent with the theoretical analysis. Because no optical filter is employed and only two MZMs are used, the system exhibits a simple structure, good performance and is low cost.

International audience; Amazonian evergreen forests show distinct canopy phenology and photosynthetic seasonality but the climatic triggers are not well understood. This imposes a challenge for modeling leaf phenology and photosynthesis seasonality in land surface models (LSMs) across Amazonian evergreen forest biome. On continental scale, we tested two climatic triggers suggested by site observations, vapor pressure deficit (VPD), and short-wave incoming radiation (SW) for defining leaf shedding and incorporated VPD- and SW-triggered new canopy phenology modules in the ORCHIDEE LSM (hereafter VPD-AP and SW-AP versions). Our results show that both VPD and SW are plausible precursors of large scale litterfall seasonality across the basin by comparing against in situ data from 14 sites. Specially, both VPD-AP and SW-AP correctly capture the increases in litterfall during the early dry season, followed by a flush of new leaves with increasing photosynthetic rates during the later dry season. The VPD-AP version performs better than the SW-AP version in capturing a dry-season increase of photosynthesis across the wet Amazonia areas where mean annual precipitation exceeds 2,000 mm yr$^{-1}$, consistent with previous satellite data analysis. Both VPD-AP and SW-AP model versions perform well in northern, central and southern Amazon regions where the SW seasonality is unimodal, but miss the seasonality of satellite GPP proxies in the eastern region off the coast of Guyana shield where SW seasonality is bimodal. Our findings imply that atmospheric dryness and sunlight availability likely explain the seasonality of leaf shedding and leaf flush processes, respectively, and consequently control canopy photosynthesis in Amazonian evergreen forests

A series of unique macrocyclic HDACs 1, 2, and 3 selective inhibitors were identified with good enzymatic activity and high selectivity over HDACs 6 and 8. These macrocyclic HDAC inhibitors used an ethyl ketone as the zinc-binding group. Compounds 25 and 26 stood out as leads due to their low double-digit nM EC50s in the 2C4 cell-based HIV latency reactivation assay. The PK profiles of these macrocyclic HDAC inhibitors still needed improvement.

Living in the heart of Eurasia, the Kyrgyz ethnic minority have a complex human evolutionary and migration history. However, the genetic architecture of the Kyrgyz population has not been fully explored. We studied 526 Kyrgyz samples from Kizilsu Kirghiz Autonomous Prefecture in Xinjiang using the Investigator® DIPplex kit. All loci followed Hardy-Weinberg equilibrium (HWE). The combined power of discrimination (CPD) and combined power of paternity exclusion (CPE) was 0.9999999999988 and 0.9936, respectively. Compared with 90 reference populations, five InDels (HLD99, HLD81, HLD64, HLD118, and HLD111) have the potential to distinguish the Kyrgyz/Uyghur/Kazak population from other East Asian populations. Our results suggested a close genetic relationship between the Kyrgyz population and the Uyghur/Kazak populations, followed by South Asian populations. This was in accordance with the inland migration hypothesis or modern human migration influenced by warfare. Overall, this system can be used as a powerful tool in forensic individual identification and as a complementary tool in paternity cases and biogeographic ancestry analyses.

This paper involves solving the generalized sensor calibration problem ${AR}={RB}$ with rotations ${A, B, R} \in SO(3)$ , where ${A, B}$ are known and ${R}$ is to be figured out. We introduce a methodology called the quaternion decomposition from rotation (QDR) to obtain a robust solution to this problem. The method is applicable to all those cases where ${A, B}$ are noise-free, noisy, or even not rigid. The non-iterative framework of the eigen-decomposition of $4 \times 4$ matrices is derived to give very computationally efficient analytical quaternion result. By numerical examples and experimental robotic results, the effectiveness of the proposed method has been verified. The proposed solution is evaluated to own at least the same accuracy and robustness of currently best algorithm, using real-world experiments for the camera/magnetometer sensor calibration on a quadrotor, while it takes much faster computation speed than all existing representatives to the best of our knowledge.

A filter paper with a large number of nanopores and channels is vital for highly efficient nanofiltration to significantly increase the water flux without sacrificing the separation efficiency. In ...

Surface ligand-removed and Cd-rich CdSe quantum dots (QDs) exhibited exceptional activity as photocatalyst for the conversion of CO2 to CO. A CO production rate up to 789 mmol g-1 h-1 was achieved in a triethylamine/dimethylformamide mixture under visible-light irradiation. Mechanistic studies revealed that improving the Cd/Se stoichiometric ratio and exposing more active surface Cd atoms significantly enhanced the activity of CdSe QDs for CO2 photoreduction.

Dust particles are hazardous to human health and severely affect the city operations. However, there is few research on the topographic dynamic removal of near-surface dust particles. In this study, the surface meteorological and aerosol monitoring data if such an event was analysed. The event took place on March 27–29, 2018 in Beijing, China. Given the special topographic conditions in Beijing, various parameters, such as wind profile line data, four-dimensional variation Doppler radar data, and aerosol lidar data were used to determine the dynamic effects of easterly wind. The event could be divided into four stages. In Stage 1 (Dust aerosol transfer), the dust particles at higher elevation were transferred to upper atmosphere of Beijing through northern wind. These dust particles gradually moved to the lower atmosphere. The temperature inversion layer hindered the settlement of dust particles on the near-surface atmosphere. The dust particles could not penetrate the temperature inversion layer and moved to the near-surface layer. Anthropogenic aerosols of high concentrations were retained below the height of 1 km. In Stage 2 (development of dust particles), following the dynamics of easterly wind, the temperature inversion phenomenon gradually disappeared. The high-concentration dust particles in the higher atmosphere were transferred to the near-surface layer and settled down, thus mixing with the anthropogenic aerosol particles. In Stage 3 (decreasing dust aerosol concentration in the middle troposphere), the easterly wind clearly strengthened in the middle troposphere. Above this layer, the easterly wind weakened with height and formed uplifting airstreams, which coupled with the southerly airstream formed by the upper trough above Beijing. Furthermore, high-concentration aerosols were lifted to a certain height and could not spread to the upper atmosphere because of sinking airflow. In Stage 4 (removal of dust particles), the easterly wind reached the strength of low-level jet streams. The south-westerly wind was present above 2.5 km height. The high aerosol concentrations at the height of 2.0 km and below were lifted to the upper atmosphere and blown downstream by the strong south-westerly wind and the easterly wind coming from clean-ocean air masses, thereby concluding the dust particles’ event.

Renowned for its high theoretical specific energy, lithium-sulfur (Li–S) batteries still suffer from the shuttle effect of polysulfides, the insulating nature of sulfur and severe volumetric variations, especially for cathodes with high sulfur contents. Herein, S microsphere encapsulated within a thickness-tunable multilayered thin V/V2O5 nanoshell (S@V/V2O5) was explored as a high-sulfur-content cathode (up to 93 wt%) for Li–S batteries. With a polar V2O5 moiety the nanoshell could physically block and chemically adsorb polysulfides, while the metallic V could assure efficient electron transfer; this multilayered and porous nanoshell could also buffer the volumetric variations of the sulfur core and facilitate Li+ transportation. Such S@V/V2O5 electrode with a 87 wt% sulfur content delivers high specific capacity (1403 mAh g−1) and remarkable areal initial capacity (4.4 mAh cm−2) at 0.2 C, excellent cycling stability (819 mAh g−1 at 0.5 C after 300 cycles), superior high-rate capacity (804 mAh g−1 at 4 C), low self-discharge (759 mAh g−1 after resting 50 days) and a high coulombic efficiency above 90% in a LiNO3-free electrolyte. A current collector-free S@V/V2O5 cathode with sulfur content of 93 wt% is also achieved, which yields stable discharge capacity of 1000 mAh g−1 at 0.2 C after 100 cycles.