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Given the difficulties in rescuing and ensuring the quality of long-term climate data, current studies on century-scale climate change are usually limited to annual and monthly data, resulting in the poor detection of extreme climate events and their changes before 1950. In this study, we reconstructed a daily precipitation series for Tianjin from 15 September 1887 to 31 December 2022 on the basis of the most comprehensive daily precipitation records collected from the Tianjin Meteorological Archive, China, and in reference to the precipitation analysis results based on the datasets developed by the Climatic Research Unit Time-Series version 4.06, Global Precipitation Climatology Centre and University of Delaware along with the application of various homogenisation methods for climate series. Our approach provides a complete and reliable century-long daily precipitation series for the study of regional or local extreme weather and climate events. The reconstructed daily dataset reveals that the annual precipitation amount and R95 intensity in Tianjin during 1888–2022 lack significant trends and have values of 0.74 ± 6.99 and −1.84 ± 3.22 mm per decade, respectively. On the annual and seasonal scales, the precipitation amount and R95 intensity, particularly those in autumn, have increased since the latter half of the 20th century relative to those in 1888–1950. However, the increase in precipitation amount and R95 intensity is relatively limited compared with that in atmospheric water vapour content due to surface warming, indicating the highly sensitive response of extreme precipitation events to warming. In addition, the estimates for the return periods of 5, 10, 20, 50 and 100 years covering 1888–2022, 1888–1950 and 1951–2022 depict that the intensity of heavy rain and above magnitude was highest in 1888–1950 and decreased in 1951–2022.

Foldable wings are designed for tube-launched unmanned aerial vehicles (UAVs), aiming to improve portability and meet launch platform requirements. However, conventional tube-launched UAVs cannot operate across the wide speed ranges required for the performance of multiple missions, due to the fixed configuration of their wings after launch. This study therefore proposes a tube-launched UAV which can change wing-sweep angle to expand the flight speed range and enhance the UAV’s agility. A computational aerodynamics method is employed to assess the transient aerodynamic performance of the UAV during the sweep morphing process. The simulation results indicate that the transient aerodynamic forces generate a dynamic hysteresis loop around the quasi-steady data. The lift and drag coefficients exhibit maximum relative deviations of 18.5% and 12.7% from the quasi-steady data for the sweep morphing period of 0.5 s. The hysteresis effect of the flow structure, rather than the additional velocity resulting from wing-sweep morphing, is the major contributor to the aerodynamic hysteresis loop. Compared to the conventional tube-launched UAVs, the proposed tube-launched UAV with a variable-sweep wing shows a wider flight speed range, from 22.59 to 90.12 m/s, and achieves an 82.84% increase in loitering speed. To verify the effectiveness of the wing-sweeping concept, a prototype was developed, and a flight test was carried out. The test data obtained from flight control system agree well with the simulation data, which demonstrates the feasibility and effectiveness of the variable-sweep wing in widening the speed range for tube-launched UAVs. This work can provide a reference for the design of tube-launched UAVs for wide speed range flight.

Driven by the increase in its frequency and duration, high temperature weather is increasingly seriously affecting crop development. High temperature inhibits the leaf development, flowering, and pollination of cotton, but its effects on the roots and root hair phenotypes and lifespans remain unclear. Thus, this study selected the two cotton varieties Nongda 601 (ND) and Guoxin 9 (GX) as materials and adopted the RhizoPot, an in situ root observation system, to investigate the effects of high temperature (38°C day and 32°C night) on the growth dynamics of the aboveground parts and root phenotypes of cotton at the seedling stage. The results showed that high temperature reduced the net photosynthetic rate and chlorophyll content, decreased the dry matter accumulation and transfer to the root, and lowered the root-shoot ratio (R/S ratio). The root phenotypes changed significantly under high temperature. After 7 d of high temperature stress, the root lengths of ND and GX decreased by 78.14 mm and 59.64 mm, respectively. Their specific root lengths increased by 79.60% and 66.11%, respectively. Their specific root surface areas increased by 418.70 cm2·g-1 and 433.42 cm2·g-1, respectively. Their proportions of very fine roots increased to 99.26% and 97.16%, respectively. After the removal of high temperature (RHT), their root lengths tended to increase, and their proportions of very fine roots continued to increase. The root hairs of ND and GX were also significantly affected by high temperature. In particular, the root hair densities of ND and GX decreased by 52.53% and 56.25%, respectively. Their average root hair lengths decreased by 96.62% and 74.29%, respectively. Their root hair lifespans decreased by 7 d and 10 d, respectively. After the RHT, their average root hair lengths failed to recover. A principal component analysis indicated that the root architectures were significantly affected by root hair density, average root hair length, specific root length, and specific root surface area under high temperatures. In summary, cotton adapts to high temperature environments by increasing the specific root length, specific root surface area, and the proportions of very fine roots, and reducing the lifespan of root hairs.

While rapid urbanization promotes social and economic development, it exacerbates human outdoor thermal comfort, which increases the risks to human health. This paper uses four thermal comfort indices and multiple satellite observations to explore the urbanization effect on summer heat stress in Guangdong from 1979–2018, a coastal province of China. Two types of thermal comfort index are used here, namely the direct thermal comfort index (Heat Index, HI; Temperature–Humidity Index, THI; Discomfort Index, DI) and the physiological thermal comfort index (Universal Thermal Climate Index, UTCI). We compare the differences in the urbanization effects on the changes in the three direct thermal comfort indices (HI, THI, and DI) and a physiological thermal comfort index (UTCI). The results show that all four thermal comfort indices indicate an overall warming trend. Of them, urban sites show a higher warming trend than rural sites, indicating that heat stress changes are significantly influenced by urbanization from 1979–2018, which is consistent with the effect of urbanization on surface air temperature. However, except for the UTCI, this warming of direct thermal comfort indices affected by urbanization has become insignificant under the regional vegetation greening from 2004–2018 (also consistent with surface air temperature). This is primarily attributed to the different effects of wind speed on the physiological thermal comfort index in urban and rural areas: Decreasing wind speeds in urban areas lead to an increase in UTCI, while wind speeds in rural areas increase instead and decrease UTCI, thus widening the UTCI differences between urban and rural areas. Our results indicate that urbanization has a different effect on thermal comfort indices. When using the thermal comfort index, it is necessary to consider that different thermal comfort indices may bring different results. UTCI considers more factors that affect human heat perception, so it can better describe human outdoor thermal comfort. It also highlights the importance of urban ventilation and urban greenness in mitigating urban outdoor thermal comfort in the sustainable construction of future urbanization in coastal cities.

Malic acid is a component of the rhizosphere exudate and is vital for crop growth. However, little information is available about the effects of external applications of malic acid on the nutrient absorption and quality of grape fruit, and few studies have been performed on the relationship between the changes in the rhizosphere microbial community and nutrient absorption and fruit quality of grapes after adding malic acid. Here, the LM (low concentration of malic acid) and HM (high concentration of malic acid) treatments comprised 5% and 10% malic acid (the ratio of acid to the total weight of the fertilizer) combined with NPK fertilizer, respectively. Applying malic acid changed the grape rhizosphere microbial community structure and community-level physiological profile (CLPP) significantly, and HM had a positive effect on the utilization of substrates. The microbial community structure in the rhizosphere of the grapes with added malic acid was closely related to the CLPP. The N and P content in the leaves and fruits increased after applying malic acid compared to the control, while K content in the fruits increased significantly. In addition, malic acid significantly reduced the weight per fruit, significantly increased soluble sugar content (SSC) and vitamin C content of the fruit, and significantly improved the fruit sugar-acid ratio and grape tasting score. Moreover, the principal component analysis and grape nutrient and fruit quality scores showed that grape nutrients and fruit quality were significantly affected by malic acid and ranked as 5% malic acid > 10% malic acid > control. Pearson’s correlation heatmap of microbial composition, nutrient absorption and fruit quality of the grapes showed that the grape microbial community was closely related to grape nutrients and fruit quality. Adding malic acid was positively correlated to Planococcaceae, Bacillaceae, Woeseiaceae and Rhodobacteraceae. Furthermore, Planococcaceae, Bacillaceae, Woeseiaceae and Rhodobacteraceae were closely related to grape nutrient absorption and fruit quality. Bacillaceae and Woeseiaceae were positively correlated with total soluble sugar, while Planococcaceae and Rhodobacteraceae were positively correlated with titratable acid. Hence, Bacillaceae and Woeseiaceae were the key bacteria that played a major role in grape fruit quality and nutrient absorption after applying malic acid water-soluble fertilizer.

High-crystallinity and low-defect graphene nanosheets with nano pores were prepared from natural flake graphite via high-pressure homogenization liquid phase exfoliation method.The morphology and structure of as-prepared samples were investigated with scanning electron microscopy,transmission electron microscopy, atomic force microscope, X-ray diffraction and Raman spectroscopy.The electrochemical performance was performed using coin cells assembled in an argon-filled glovebox.It was found that the wrinkled graphene sheets with nanoholes consisted of 5 layers,which had high crystallinity.As conductive additives for LiFePO4 cathode,graphene constructed fast pathway for electron and ion transport in the bulk electrode,resulting in superior rate performance.Electrochemical tests showed that the electrode achieved a high reversible capacity of 90 mAh/g at 10 C rate;in addition,the discharge capacity achieved 90 mAh/g when charging and discharging at 5 C rate for 200 cycles,maintaining 100% capacity retention.The approach preparing graphene is facile,which can be suitable for industrial scale production of graphene materials.

Mn2O3/Fe2O3/few layer graphene/sulfur composites were prepared by melted salt method, interlayer catalytic exfoliation, annealing and melt diffusion method in sequence for lithium-sulfur batteries cathode. The three-dimensional conductive network formed by highly conductive few layers graphene provides electron transfer channel, thus promoting the high capacity performance of lithium-sulfur batteries. The metal oxides distributed uniformly on the surface of graphene exhibit strong interaction towards polysulfides, which can restrain the dissolution of polysulfides and shuttle effect and promote the cycling performance of lithium-sulfur batteries. As a result, the Mn2O3/Fe2O3/FLG30/S cathode shows high capacity and cycling performance. The cathode delivers an initial discharging capacity of 886.3 mAh·g-1 with a high capacity retention of 88.1% after 100 cycles at rate of 0.1 C.

Lithium metal has the lowest redox potential (-3.04 V vs standard hydrogen electrode) and extremely high specific capacity (3860 mAh·g-1), making it the ideal anodes materials for lithium secondary batteries. However, during the electrochemical cycling, due to the nonuniform nucleation growth of lithium, lithium dendrites are generated on its surface, and continue to grow and pierce the separator, causing short-circuiting of the batteries and even a fire. In the face of increasing energy density requirements, lithium metal anodes have once again become the focus all over the world. Therefore, it is necessary to protect the lithium metal anodes, suppress negative problems, and exert high performance. The artificial solid electrolyte interphase technology is an effective protection strategy for lithium metal anodes, which is essentially coating the surface of lithium metal with protective layers in advance. The artificial solid electrolyte interphase layers should have good ionic conductivity and electrochemical stability, high barrier property and mechanical strength, which can make the lithium metal anodes have high efficiency, long-term life and dendrites-free properties.The artificial solid electrolyte interphase technology brings hope to lithium metal anodes applications. In this review, the research progress of artificial solid electrolyte interphase strategy for lithium metal anodes protection in recent years was reviewed, the preparation methods, structural characteristics, cycling performances of lithium metal anodes and other aspects were introduced in detail. The specific application and performances of artificial solid electrolyte interphases in lithium secondary batteries were for summarized. Moreover,the current problems were analysed and it was pointed out that for researches of lithium metal anodes, not only the mechanism research need to be strengthed, but also needs to be combined with practical applications.

Lithium-ion batteries (LIBs) have been considered a promising candidate of new energy storage device. Numerous researchers around the world are committed to develop new materials for high-performance LIBs. MXenes are new type of two-dimensional nanomaterials, which are composed of transition metal, carbides or/and nitrides, with large specific surface area, good electrical conductivity, high lithium storage capacity, excellent cycling and rate performances, etc., making them as LIBs materials with bright application prospects. A variety of MXenes materials (such as Ti2CTx, Ti3C2Tx, V2CTx, Nb2CTx, etc.) have been reported to be useful as LIBs electrode materials. In addition, MXenes materials can be combined with other LIBs active materials to build good conductive network, accelerate electron transport and lithium ion diffusion, and inhibit materials pulverization caused by volume expansion of active materials during electrochemical processes. Besides, researches on MXenes materials in solid electrolytes, binders, and conductive agents for LIBs have also been reported. In this paper, the major breakthroughs in the application of MXenes materials for LIBs were reviewed. The preparation methods, structural properties and lithium storage mechanism of MXenes materials were introduced. Moreover, the specific application, existing problems of MXenes materials in LIBs have been concentrated on.This review points out that researches of MXenes materials should take advantages of their hydrophilicity and conductivity poperties,and focus on the development of composite electrode meterials,self-supporting electrodes materials etc.,which will bring breakthroughs to the key technologies of high-performance lithium-ion batteries.

The dynamic vibration absorber (DVA) has a broad application background in slender structure vibration reduction, such as in machine gun systems, micro actuators, and so on. Rapid modeling and simulation of the DVA-beam system are of great importance for dynamic performance, evaluation, and finally, the structural design. The primary motivation for this paper is to present a reliable and convenient technique for the modeling and computation of the DVA-beam system. A novel DVA-beam element, which consists of a beam segment and a DVA, is presented. In this element, the DVA position can be arbitrarily allocated, whether on the beam node or within the beam domain. In this way, the beam can be modeled with a few elements to save on computing costs and maintain ideal modeling accuracy. An element deactivating method, which endows the DVA-beam element with the ability to simulate a bare beam and a DVA-beam structure simultaneously, is proposed. Some numerical examples were carried out to validate the reliability of the DVA-beam element in addressing different kinds of boundary conditions by comparing the beam tip responses with those simulated by ADAMS software, and good agreements were observed. Finally, two DVA optimization examples were conducted to investigate the effectiveness and applicability of the DVA-beam element in engineering optimization. The performance was impressive.

The high concentration graphene aqueous dispersion was obtained by high-pressure homogenization liquid phase exfoliation (HPH-LPE) of flake graphite in water. The effect of surfactant concentration, HPH pressure and cycle number on the concentration of graphene dispersion CG was studied by UV-Vis spectra. The structure and morphology of graphene were analyzed by Roman spectra, SEM and TEM. The results indicate that CG is obtained up to 324.3mg·L-1 for the first time by the parameters optimization, which is 10 times higher than that obtained by sonication; graphene obtained has few defects, thin thickness and large size, indicating the good quality of graphene production; the conductivity of free-standing film prepared by the obtained graphene dispersion can reach 3.2×104S·m-1.

Two types of ultrathin-flaky δ-MnO2 electrode materials (denoted as δ-MnO2-A and δ-MnO2-B) were synthesized through the reduction of potassium permanganate with manganese acetate and ethanol separately.The crystalline structure,chemical component,microstructure and pore size distribution of these nano-materials were determined by XRD,XPS,SEM/TEM and BET analysis.The electrochemical test demonstrates two δ-MnO2 electrode materials own similar specific capacitance and rate capability.Comparing to δ-MnO2-A,however,electrode material δ-MnO2-B contains a higher potassium and manganese vacancy content,and the lamellar structure of δ-MnO2-B is more legible and stable,therefore it displays a much more superior cycling stability.In 0.5mol/L Na2SO4 electrolyte,the specific capacitance of δ-MnO2 reaches 227F·g-1(1mV·s-1) and the capacitance retention rate is achieved 87.6% after 5000 cycles at 100mV·s-1.

A new type globular MnO2 flowers anchored graphene composites was synthesized via redox reactions among potassium permanganate/ethanol/graphene. The crystalline structure, chemical component, and microstructure of the composites were determined by XRD, TG, SEM/TEM and BET analysis. The electrochemical test demonstrates the globular MnO2 material possesses excellent specific capacitance while poor rate capability and cycling stability. By means of anchoring these globular MnO2 flowers onto graphene, the specific capacitance of graphene is significantly improved. Meanwhile, rate capability and cycling stability of the globular MnO2 material can be promoted remarkably. In 0.5mol/L K2SO4 electrolyte, the specific capacitance of the composites reaches as high as 295F·g-1 at 2mV·s-1, and maintains at 102F·g-1 even at a high scan rate of 1000mV·s-1.An outstanding capacitance retention of 96.3% is achieved for the composites after 1000 cycles at 100mV·s-1. It demonstrates the globular MnO2 flowers anchored graphene composites is a very potential electrode material for supercapacitors.

This paper presents a miniature Linear Series Elastic Actuator (LSEA), in which two low-cost linear potentiometers were adopted to achieve a compact design. To improve the measurement accuracy of the linear potentiometer, a novel Bezier-based Calibration Method (BCM) and its optimization method were proposed to calibrate the inherent nonlinearity of the linear potentiometer. Calibration efficiency of the BCM was investigated numerically by making a comparison with the widely used Polynomial Calibration method (PCM), and the effect of the BCM calibration on the control performance of the LSEA was investigated experimentally by displacement and force control. Results reveal that the BCM exhibits an excellent local calibration ability for the nonlinearity with knee points. Due to the above characteristic, the BCM could produce a better calibration accuracy than the PCM under the same model order and improve the control performance of the LSEA. In addition, the BCM could calibrate the inherent nonlinearity of the potentiometer in a continuous form rather than that of piecewise ones. The continuous calibration form could bring more convenience to practical applications.

Although polyurea has attracted extensive attention in impact mitigation due to its protective characteristics during intensive loading, the ballistic performance of polyurea-reinforced ceramic/metal armor remains unclear. In the present study, polyurea-reinforced ceramic/metal armor with different structures was designed, including three types of coating positions of the polyurea. The ballistic tests were conducted with a ballistic gun; the samples were subjected to a tungsten projectile formed into a cylinder 8 mm in diameter and 30 mm in length, and the deformation process of the tested targets was recorded with a high-speed camera. The ballistic performance of the polyurea-reinforced ceramic/metal armor was evaluated according to mass efficiency. The damaged targets were investigated in order to determine the failure patterns and the mechanisms of interaction between the projectile and the target. A scanning electron microscope (SEM) was used to observe the microstructure of polyurea and to understand its failure mechanisms. The results showed that the mass efficiency of the polyurea-coated armor was 89% higher than that of ceramic/metal armor, which implies that polyurea-coated ceramic armor achieved higher ballistic performance with lighter mass quality than that of ceramic/metal armor. The improvement of ballistic performance was due to the energy absorbed by polyurea during glass transition. These results are promising regarding further applications of polyurea-reinforced ceramic/metal armor.

LiFePO4-C/graphene composite was successfully prepared by a facile approach of grinding, ultrasonic dispersion, stirring and drying and used as the cathode material for lithium-ion batteries.The structure and morpholgy of as-prepared LiFePO4-C/graphene composite material was characterized with transmission electron microscopy,scanning electron microscopy, X-ray diffraction and Raman spectroscopy,and the electrochemical performance was tested using coin cells assembled in an argon-filled glovebox. SEM images show that in the as-prepared material, graphene nanoflakes are adhered on the surface of LiFePO4-C particles, and uniformly dispersed in the composite material forming an effective 3D conducting network. Electrochemical tests show that after adding 2% of graphene, rate and cycling performances of the LiFePO4-C/graphene composite material are obviously improved. For the rate performance, a high reversible capacity of 94.2mAh·g-1 is achieved at 5C rate,which is more than 2.53 times higher than that of pristine LiFePO4-C; For cycling performance, the composite material shows a low capacity decay rate of 9.6% when cycles under 1C rate for 100 times,which is lower than pure LiFePO4-C (43.5%). The electrochemical performance enhancement can be mainly ascribed to the effective 3D conducting network formed by graphene nanoflakes with superior conductivity.

Graphene is an ideal material for energy storage application as its excellent mechanical and physical properties. 3D printed graphene materials will be widely applied in energy storage field for its precisely controllable structure and it is easy to realize large-scale preparation. In this paper, the progress of 3D printed graphene materials synthesis technology and its application in energy storage field were reviewed. The viscosity and printability of graphene ink are key factors for realizing graphene 3D printing. Scalable preparation of graphene ink with facile process, controllable concentration and additive free will be the research focus of graphene 3D printing technologies in the future. The integrated printing of graphene energy storage devices such as graphene supercapacitor, lithium-sulfur battery and lithium ion battery is the development direction in this area.

Abstract Optical Coherence Tomography (OCT) imaging of living subjects offers increased depth of penetration while maintaining high spatial resolution when compared to other optical microscopy techniques. However, since most protein biomarkers do not exhibit inherent contrast detectable by OCT, exogenous contrast agents must be employed for imaging specific cellular biomarkers of interest. While a number of OCT contrast agents have been previously studied, demonstrations of molecular targeting with such agents in live animals have been historically challenging and notably limited in success. Here we demonstrate for the first time that microbeads (µBs) can be used as contrast agents to target cellular biomarkers in lymphatic vessels and can be detected by OCT using a phase variance algorithm. This molecular OCT method enables in vivo imaging of the expression profiles of lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), a biomarker that plays crucial roles in inflammation and tumor metastasis. In vivo OCT imaging of LVYE-1 showed that the biomarker was significantly down-regulated during inflammation induced by acute contact hypersensitivity (CHS). Our work demonstrated a powerful molecular imaging tool that can be used for high resolution studies of lymphatic function and dynamics in models of inflammation, tumor development, and other lymphatic diseases.

The rhizosphere microenvironment is the site of nutrient circulation and microbial community formation, and thus is an ongoing topic of research. Although research on this topic is extensive, studies into the rhizosphere microenvironment of fruit trees remain rare. To elucidate the mechanisms driving the fruit tree rhizosphere microenvironment, we assessed soil physicochemical properties, enzyme activities, the community-level physiological profile (CLPP) and microbial diversity in rhizospheric soils of eight common deciduous fruit trees in northern China. We found that the available minerals, pH, enzyme activities, microbial utilization of six types of carbon (C) substrates, and microbial diversity in the rhizosphere varied among tree species. Redundancy analysis (RDA) showed that rhizosphere microenvironmental parameters (ammonia nitrogen content, soil pH and invertase activity) were closely related to the soil microbial community. Further analysis revealed that the soil microbial utilization of six C sources, nitrate nitrogen content, and invertase activity were negatively correlated with Ambiguous species and Alternaria; however, these groups were positively correlated with pH. The ammonia nitrogen content was positively correlated with C source utilization and negatively correlated with Ambiguous, Lysobacter, Nitrospira, Alternaria, Fusarium, and Colletotrichum. Interestingly, invertase was closely linked to the microbial community, especially fungal diversity, and was positively correlated with plant-beneficial microbes such as Mortierella, Geomyces, Lysobacter, and Chaetomium, but negatively correlated with pathogenic microbes such as Alternaria, Fusarium, and Colletotrichum. Hence, rhizosphere soil physicochemical properties, enzyme activities and microbial community were significantly affected by tree species. Additionally, a variety of environmental factors were closely related to the microbial community in the rhizospheric soils of eight species of deciduous fruit trees.

Excessive recoil severely restricts the loading of high-power traditional guns on modern vehicles. To reduce the recoil without breaking the continuous firing mode and reducing the projectile velocity, a recoil reduction method that controls the lateral ejecting of propellant gas by a piston was proposed. The recoil reduction device is symmetric about the barrel axis. First, a one-dimensional two-phase flow model of interior ballistic during the gun firing cycle was established. Next, the MacCormack scheme was used to simulate, and the piston motion was gained. Then the propagation of the rarefaction wave in the barrel was presented. Finally, the propulsion difference between the piston-controlled gun and the traditional gun was discussed. The results showed that the recoil momentum was reduced by 31.80%, and the muzzle velocity was decreased by just 1.30% under the reasonable matching of structural parameters.