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With the development of high temperature fields, such as automotive, petroleum, nuclear power and aerospace, piezoelectric materials with wide temperature range, as the core component of nondestructive testing and sustainable self-powered equipment used in these extreme environments, have become the hotspot of research in recent years. However, even the piezoelectric materials with wide temperature range owning excellent piezoelectricity and high temperature stability, the devices made of them could not have both flexibility and high-temperature resistance due to the embrittlement and hardness, resulting in the limitation in the application of high temperature precision operation and wearable health testing. Therefore, the flexible design of piezoelectric materials with wide temperature range, which can realize the preparation of high-temperature resistant, soft piezoelectric device and ultimately broaden the high temperature potential of device, become an important development direction for piezoelectric field. The research progress of piezoelectric materials with wide temperature range was introduced first in this paper, which includes materials (PZT, BT, KNN) used in the environment below 300 ℃ and Ⅲ-N material used in 500-1000 ℃. Then the flexible design technology was collected based on these materials, including direct-growth, growth-transfer and nano-composite. In the meantime, the influence of types of substrates or composite matrix on the high-temperature stability of final device was also analyzed.

Hydrology is an important environmental factor for the evolution of wetland landscape patterns. In the past 20 years, Poyang Lake, the largest freshwater lake in China, has experienced significant inundation shrinkage and water level decrease, posing a significant threat to the local vegetation community. To explore the potential relationship between aquatic vegetation and hydrological processes in the recent hydrological situation, in this study, the landscape patterns of aquatic vegetation communities in Poyang Lake were studied using time-series Landsat remote sensing images and a support vector machine classifier. The stepwise regression analysis method was adopted to analyze the relationship between the vegetation area and hydrological factors. The results indicated that the area of submerged and emergent vegetation in the entire lake decreased significantly from 2001 to 2017, whereas the area of moist vegetation showed a remarkably increasing trend. The average distribution elevation of the submerged vegetation increased by 0.06 m per year. The corresponding landscape patterns showed that the degree of fragmentation of aquatic vegetation communities in Poyang Lake increased. Several hydrological factors were selected to quantify the potential impact of water level fluctuations. The correlation analysis results indicated that hydrological conditions during the rising- and high-water periods may be the key factors affecting the area of aquatic vegetation. This study systematically investigated the evolution of vegetation communities in Poyang Lake wetlands over the past two decades, which contributes to the protection and management of this unique ecosystem. [ABSTRACT FROM AUTHOR]

Aircraft icing has historically been a critical cause of airplane crashes. The electro-impulse de-icing system has a wide range of applications in aircraft de-icing due to its lightweight design, low energy consumption, high efficiency, and other advantages. However, there has been little study into accurate wing electric-impulse de-icing simulation methods and the parameters impacting de-icing efficacy. Based on the damage mechanics principle and considering the influence mechanisms of interface debonding and ice fracture on ice shedding, this paper establishes a more accurate numerical model of wing electric-impulse de-icing using the Cohesive Zone Model (CZM). It simulates the process of electric-impulse de-icing at the leading edge of the NACA 0012 wing. The numerical results are compared to the experimental results, revealing that the constructed wing electro-impulse de-icing numerical model is superior. Lastly, the effects of varying ice–skin interface shear adhesion strengths, doubler loading positions, and impulse sequences on de-icing effectiveness were studied. The de-icing rate is a quantitative description of the electro-impulse's de-icing action, defined in the numerical model as the ratio of cohesive element deletions to the total elements at the ice–skin interface. The findings reveal that varying shear adhesion strengths at the ice–skin interface significantly impact the de-icing effect. The de-icing rate steadily falls with increasing shear adhesion strength, from 66% to 56%. When two, four, and seven impulses were applied to doubler two, the de-icing rates were 59%, 71%, and 71%, respectively, significantly increasing the de-icing efficiency compared to when impulses were applied to doubler one. Doubler one and two impulse responses are overlaid differently depending on the impulse sequences, resulting in varying de-icing rates. When the impulse sequence is 20 ms, the superposition results are optimal, and the de-icing rate reaches 100%. These studies can guide the development and implementation of a wing electric-impulse de-icing system. [ABSTRACT FROM AUTHOR]

In recent years, due to the increasingly powerful functions of tablets, more and more people have used tablets. The failure of the screen caused by debonding failure between the screen and the case of the tablet due to drops will affect the normal use of the tablet. However, there have been few studies on the debonding methods of the screen and the case of the tablet, as well as the factors influencing the debonding between the screen and the case of the tablet. Numerical analysis software was used in this paper to simulate the iPad Air (Air) drop process, and the cohesive zone model and tiebreak contact were used to simulate the debonding process between the screen and case of the Air tablet, respectively. When the results are compared to the experiments, the results show that the cohesive zone model is superior. The effects of various rounded corner radii, drop postures in the XY plane, materials of the outer case, and strain rates of PC/ABS on the localized debonding between the outer case and outer glass of the Air during the drop process were investigated. The degree of debonding between the Air model's outer case and outer glass is defined by t, which is the ratio of the area of the deleted cohesive elements to the total area of the cohesive elements. The results show that the rounded corner radius and the strain rate of PC/ABS have less influence on t; the t of the Air model dropped at 45° in the XY plane is 37.7% of that dropped at 0° and 90°; and the t of the Air model with glass as the outer case material is 48% of that with aluminum alloy as the outer case material. These studies serve as a foundation for tablet design and material selection. [ABSTRACT FROM AUTHOR]

In the field of agricultural machinery, various empirical field tests are performed to measure the tillage force for precision tillage. However, the field test performance is costly and time-consuming, and there are many constraints on weather and field soil conditions; the utilization of simulation studies is required to overcome these shortcomings. As a result, the SPH method and the coupled FEM-SPH method are used in this paper to investigate the mouldboard plough–soil interaction. In this paper, the finite element software LS-DYNA was used to build the SPH model and the FEM-SPH coupling model of soil cutting, as well as to investigate the change in cutting resistance during the soil cutting process. The simulation results are compared with those of the experiments, and the curves of the simulation and experiment are in good agreement, which verifies the reliability of the model. The validated simulation model was used to investigate the effects of the cutting speed, depth of cut, inclination angle, and lifting angle of the mouldboard plough on cutting resistance. The simulation studies show that the SPH model takes 5 h and 2 min to compute, while the FEM-SPH coupled model takes 38 min; obviously, the computational efficiency of the FEM-SPH coupled model is higher. The relative errors between the SPH model and the experiment are 2.17% and 3.65%, respectively. The relative errors between the FEM-SPH coupled model and the experiment are 5.96% and 10.67%, respectively. Obviously, the SPH model has a higher computational accuracy. The average cutting resistances predicted by the SPH model and the FEM-SPH coupled model, respectively, were 349.48 N and 306.25 N; these resistances are useful for precision tillage. The cutting resistance increases with the increase in cutting speed and is quadratic; the cutting resistance increases with the increase in cutting depth and is quadratic; the horizontal cutting resistance and the combined cutting resistance increase with the increase in inclination angle, while the vertical cutting resistance remains essentially constant with the increase in inclination angle; the horizontal cutting resistance and combined cutting resistance increase as the lifting angle increases, while the vertical cutting resistance decreases as the lifting angle increases. [ABSTRACT FROM AUTHOR]

The corrosion protection of MXene-based composite coatings is challenging due to the relatively low dispersion of MXene in organic coatings. In this work, waterborne polyurethane (WPU) composites containing hybrid nanoadditives of Ti3C2Tx MXene and functionalized carbon nanotubes (CNTs) were fabricated. The thermal stability, surface hydrophobicity, surface roughness, and mechanical properties of the nanocomposites containing MXene or MXene/CNT hybrid additives were studied. Electrochemical methods, including electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization scans, were utilized to evaluate the anticorrosion properties of the nanocomposite coatings when applied to copper substrates. The polyurethane sample with 0.95 wt % Ti3C2Tx MXene and 0.05 wt % CNTs showed the lowest corrosion rate of 2.1 × 10–3 μm year–1. Additionally, the EIS results revealed that the corrosion resistance of WPU/MXene coatings significantly increased by adding 0.05 wt % CNTs. The mechanism of the improved anticorrosion performance of the WPU/MXene/CNT composite coating is illustrated. Moreover, the importance of optimizing the concentration of the CNTs is discussed to obtain better corrosion protection. The polyurethane nanocomposite coatings reported in this work present great potential as corrosion protection coatings for metals and other surfaces. [ABSTRACT FROM AUTHOR]

Metasurface is extensively studied for generating multicharacteristic orbital angular momentum (OAM) beams. However, designing a highly integrated and independent polarization‐frequency multiplexing metasurface for efficient multiscenario OAM‐related applications is still a challenge. Here, a triple‐band single‐layer shared aperture reflective metasurface for triple‐polarization channels independent OAM modulations is proposed. The specific frequency quantitative customization resonance phase and quasi‐static geometric phase are utilized to manipulate the dual‐band (Ku‐ and K‐band) orthogonal linearly polarized (LP) channel and C&X‐band right‐handed circularly polarized (RHCP) channel. An isolation ring is introduced for eliminating the strong coupling between the structurally compatible RHCP and orthogonal‐LP subunits in a shared aperture meta‐atom. It is revealed that the isolation ring not only helps realize efficient multipolarization, multiband, and multimode OAM generation, but also expands the operation bandwidth of the RHCP channel OAM. A proof‐of‐concept prototype of the designed metasurface is constructed to verify the methodology and the experimental results are in excellent agreement with simulations. The proposed independent OAM modulation scheme for extending the functionality of metasurface offers a novel route to realize multipolarization and multiband OAM beams with high isolation, which may have potential applications in OAM‐based multichannel multiplexing communications. [ABSTRACT FROM AUTHOR]

This paper discussed the investigate the risk factors of severe bleeding after ultrasound-guided percutaneous renal biopsy. 512 patients underwent ultrasound-guided percutaneous renal biopsy were retrospectively selected, the patient's serum indexes were detected, the occurrence of severe bleeding and its influencing factors were analyzed. In severe hemorrhage group, the ultrasound demarcated skin and medulla were not clear, serum creatinine (SCR) were significantly higher than those in control group (P<0.05), while the estimated glomerular filtration rate (eGFR), hemoglobin (Hb) and platelet (PLT) were significantly lower than those in control group (P<0.05). Logistic regression analysis showed that unclear boundary between skin and medulla, Scr, Hb and eGFR were the influencing factors of severe bleeding after ultrasound-guided percutaneous renal biopsy (P<0.05). Severe bleeding after ultrasound-guided percutaneous renal biopsy is affected by boundary between skin and medulla, Scr, Hb and eGFR. [ABSTRACT FROM AUTHOR]

A flexible and highly sensitive capacitive sensor capable of detecting pressure over a wide range was prepared using an elastomeric dielectric layer with high porosity and air gaps sandwiched between conducting polymer/filter paper electrodes. Porous polydimethylsiloxane (PDMS) with air gaps (i.e. through holes) was prepared by using NaCl powders and an array of metal pins as a template during the curing process. An as-fabricated capacitive sensor based on the PDMS layer with ∼60% porosity and an array of 6 × 6 air gaps with diameters of ∼850 μm showed high sensitivity for the pressure range from ∼5 Pa to 1 MPa, a quick response time and good durability. Potential applications of the capacitive pressure sensor in human motion monitoring and spatial pressure mapping were demonstrated. [ABSTRACT FROM AUTHOR]

This work outlines a general method to prepare a three-dimensional (3D), highly porous, and conductive sponge with tunable conductivity for a tactile pressure sensor. The 3D conductive sponge is prepared by the assembly of shortened/fragmented electrospun nanofibers of polyacrylonitrile (PAN), polyimide (PI), and PAN-based carbon. The nanofibers of PAN, PI, and carbon are dispersed in water/ethanol with polyvinyl alcohol (PVA) and then freeze dried to form the 3D conductive sponge. Subsequently, the sponge is thermally treated at 230 °C; and the dehydrated PVA acts as a binder to uniformly bond electrospun carbon nanofibers (CNFs) on the mechanically resilient 3D scaffold of PAN/PI. Upon varying the amounts of CNFs, the resistance of the 3D nanofibrous sponge is readily tailored from ∼260 kΩ to ∼200 Ω. The resistance change of the 3D conductive sponge under cyclic compressive strain is investigated, and the results are correlated with the unique interconnected and hierarchically structured pores in the sponge. A tactile pressure sensor array composed of 25 devices of conductive sponges is demonstrated. [ABSTRACT FROM AUTHOR]

With the aim of detecting glutaraldehyde (GA) in wastewater released from hospitals and other sites, fluorescent poly(phenyleneethynylene) with pendant protonated primary amino groups (PPE-NH3+) was synthesized and characterized. The fluorescence of the conjugated polyelectrolyte PPE-NH3+ in aqueous solution changed upon addition of aldehydes. Among many commonly encountered aldehydes including formaldehyde (FA) and glutaraldehyde (GA), GA displayed the strongest quenching of the fluorescence of PPE-NH3+. The quenching efficiency reached above 85% with 1 mM of GA and the limit of detection (LOD) was 0.49 μM. The fluorescence quenching mechanism was discussed. GA, as a dialdehyde, could react with amino groups on different polymer chains simultaneously, and thus might result in more efficient chain aggregation and quenching. Finally, this sensory system was demonstrated to be very effective in detecting GA in real water samples from a water tap in our lab, a pond on the campus, Dushu lake and a river nearby a hospital. [ABSTRACT FROM AUTHOR]

Naphtho[2,1-b:3,4-b′]dithiophene is used for the first time as the π-spacer for metal-free organic dyes in dye-sensitized solar cells (DSSCs). Four new donor–(π-spacer)–acceptor organic dyes using triarylamine or carbazole as the electron-donating group, cyanoacrylic acid as the electron-withdrawing anchoring moiety, and naphtho[2,1-b:3,4-b′]dithiophene as the linker were synthesized. The absorption, electrochemical, and photovoltaic properties of the dyes were investigated. DSSCs based on these dyes as sensitizers had efficiencies ranging from 3.98% to 4.60%. The highest efficiency was 4.60 ± 0.16% with a Jsc of 10.8 ± 0.4 mA cm−2, a Voc of 657 ± 5 mV, and a fill factor of 64.0 ± 0.2% under 100 mW AM 1.5 irradiation. The incident photon-to-current efficiency (IPCE) measurement showed that these dyes had high quantum efficiency over the visible range, and the long π-spacer of the molecule resulted in broader IPCE at long wavelength and high Jsc. Photovoltage transient was used to understand the electron recombination and the trends of the photovoltaic parameters (e.g. Voc and efficiency) of the DSSCs based on these organic dyes. [ABSTRACT FROM AUTHOR]

Abstract: In this letter, we report a novel route to prepare stable Pd/poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (Pd/PEDOT:PSS) colloid. With addition of PSS, the Pd/PEDOT:PSS aqueous dispersion was formed by simultaneous oxidation–reduction reaction between Pd(NO3)2 and ethylenedioxythiophene (EDOT) at room temperature. The morphologies of the Pd/PEDOT and Pd/PEDOT:PSS nanocomposites were characterized by transmission electron microscope. The Pd nanoparticles in the composites were identified with X-ray powder diffraction and UV/vis/NIR spectrum. The chemical structures of PEDOT were studied using FTIR spectra and UV/vis/NIR spectra. The results confirmed the formation of oxidized PEDOT polymer. The sensing property of the Pd/PEDOT:PSS thin film to the NH3 vapor was investigated. [Copyright &y& Elsevier]

• A multiscale model is built to analyze the suitable habitats for Siberian cranes. • The hydraulic model is combined with remote sensing to determine habitat features. • The impacts of the Poyang Lake Hydraulic Project on habitat suitability are revealed. • Water level regulation reduces the fragmentation degree of highly suitable habitats. • The spatial characteristics of habitats can guide habitat protection and management. Poyang Lake is located in the middle and lower reaches of the Yangtze River in China. It is the most important wintering area for the endangered Siberian cranes. Identifying the scale characteristics of habitat selection for Siberian cranes is essential for habitat conservation. In this study, a habitat suitability index (HSI) model based on multiscale habitat features was developed to assess the distribution and fragmentation degree of the suitable habitat for Siberian cranes before and after the construction of the proposed Poyang Lake Hydraulic Project (PLHP). The habitat of the entire lake area was divided into four ranks on the basis of HSI values. 2D shallow-water equations (SWEs), combined with remote sensing and geographic information system technology, were utilized to determine the key habitat features. Results indicated that the established HSI model could effectively recognize the potentially suitable habitats for Siberian cranes in Poyang Lake. The highly suitable habitat in the wet year was larger than that in the dry year, and the complexity of patch shapes and patch fragmentation increased. The influence of the PLHP on the suitable habitat for cranes mainly depended on its regulated water level, and this project could promote the formation and reduce the fragmentation degree of the suitable habitat under a properly regulated water level in the dry year. However, a higher regulated water level may cause a considerable negative impact on the distribution of suitable habitats in both years. This study provided a quantitative method to evaluate the potentially suitable habitats for Siberian cranes, and it could serve as a reference for the water level management of the proposed PLHP. [ABSTRACT FROM AUTHOR]

• A conceptual model is proposed to study the evolution of vegetation patches. • The relationship between final coverage and initial vegetation patches is revealed. • The longitudinal dispersion is usually enhanced during the vegetation evolution. • The effects of critical bed shear stress on the vegetated landscape is explored. Hydrodynamic conditions are important controlling factors in the evolution of vegetation and ecosystems, especially aquatic ecosystems. This study established a conceptual vegetation evolution model to explore the succession law of vegetation patches in the effective area of a channel, including the evolution of vegetation coverage (C e) and the corresponding longitudinal dispersion coefficient (K e). 2D shallow-water equations were implemented to calculate flow variables, and the equivalent Manning coefficient was used to reflect the effects caused by vegetation patches. New vegetation emerged in regions where the bed shear stress is lower than the critical bed shear stress, whereas the original vegetation was removed in regions where the bed shear stress is higher than the critical value. Two typical cross-sections and two initial C e were considered to better understand the succession trend of vegetation patches under different external conditions. The findings showed that C e and K e increased to a constant value with increasing simulation duration, whereas a higher critical bed shear stress, defined by the threshold value (TV), was linked to a higher final vegetation coverage (C f) and final longitudinal dispersion coefficient (K f). Furthermore, different initial vegetation distributions, including coverage and position, caused little effect on the C f in the rectangular channel, but the C f in the parabolic channel was linearly affected by the averaged bed shear stress at the initial patches. The maximum K f in both channels occurred with regularly distributed initial patches on one side of the bank. The vegetation patches in all scenarios evolved from block-shaped to strip-shaped and finally formed a stable vegetated landscape. This conceptual vegetation evolution model will improve our understanding of the influence of hydrodynamic conditions on the vegetation evolution in aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Herein, we report the transient photocurrent and photovoltage studies on the charge transport in dye sensitized solar cells (DSSCs) made from the composites of electrospun titanium oxide (TiO2) nanofibers, and conventional TiO2 nanoparticles. The results on charge transport parameters (including the charge recombination lifetime, the electron transport lifetime, and the diffusion length) indicated that the addition of TiO2 nanofibers into composite photoanodes led to substantial improvement on the efficiency of charge collection, suggesting that the composites of nanoparticles and one-dimensional nanostructures are promising materials for the development of DSSCs with high efficiency. [ABSTRACT FROM AUTHOR]