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The globally increasing frequency of extreme drought events exacerbates the contradiction between the supply of water and the demand for high-quality urban greening. However, the mechanism of the response of urban shrubs to drought stress remains unclear. In this study, three typical urban shrubs (Euonymus japonicus, golden vicary [Ligustrum × vicaryi], and Japanese purple barberry [Berberis thunbergii var. atropurpurea]) that are used for greening in northern China were exposed to three levels of water (full irrigation, natural rain-fed, and extreme drought) in different periods of the growing season (April to May, June to July, and August to September) to investigate the responses of leaf water potential and photosynthetic parameters. The main results were as follows: (1) all the leaf water potentials (Ψ) and photosynthetic parameters (Pn) showed a typical linear relationship along the water gradient in the middle of the growing season. Extreme drought decreased the photosynthetic rates by 1.26~11.03 μmol·m−2·s−1 compared with the irrigated groups. However, the responses were less pronounced in the early and late growing seasons. (2) Different shrubs responded with different intensities and mechanisms. B. thunbergii var. atropurpurea showed clear anisohydric behavior throughout the whole growing season, while L. × vicaryi and E. japonicus showed stronger isohydric behavior during the early and late growing seasons. These findings are important to improve the sustainability of maintenance of ornamental plants from the scope of the efficient utilization of urban water resources. [ABSTRACT FROM AUTHOR]

The development of green spaces in urban parks can significantly enhance the quality of the urban and ecological environment. This paper utilizes 2021 Gaofen-7 (GF-7) satellite remote sensing images as its primary data source and uses deep learning algorithms for the precise extraction of the green space coverage within Beijing's fifth ring road. It also incorporates the park points of interest (POI) information, road data, and other auxiliary data to extract green park space details. The analysis focuses on examining the relationship between supply and demand in the spatial allocation of green park spaces from an accessibility perspective. The main findings are as follows: (1) The application of deep learning algorithms improves the accuracy of green space extraction by 10.68% compared to conventional machine methods. (2) The distribution of parks and green spaces within the fifth ring road of Beijing is uneven, showing a clear pattern of "more in the north and less in the south". The accessibility within a five-minute service radius achieves a coverage rate of 46.65%, with a discernible blind zone in the southeast. (3) There is an imbalance in the per capita green space location entropy within the fifth ring road of Beijing, there is a big difference in per capita green space location entropy (44.19), and social fairness needs to be improved. The study's outcomes unveil the intricate relationship between service capacity and spatial allocation, shedding light on the supply and demand dynamics of parks and green spaces within Beijing's fifth ring road. This insight will contribute to the construction of ecologically sustainable and aesthetically pleasing living spaces in modern megacities. [ABSTRACT FROM AUTHOR]

Composite adhesive rivet hybrid connection structure has been more and more recognized and applied in aerospace, automobile, and other industries due to its high strength, corrosion resistance, and good stability. However, due to the particularity of the composite structure and the complex nonlinear coupling factors existing in the bearing process of the adhesive rivet hybrid connection structure, it is difficult to carry out structural health monitoring of the composite adhesive rivet hybrid connection structure. In this paper, a new fabrication technique is proposed to fabricate MXene thin film sensors with excellent performance. The MXene sensor can be tailored to the required size and arrangement to monitor the hybrid connection structure. The multi‐stage loading‐unloading test verifies the feasibility of using the MXene sensor to monitor the hybrid connection structure. The monitoring curves of the MXene sensor for composite adhesive rivet mixed connection structure specimens under low‐speed impact test and vibration fatigue test were obtained, and the sensing mechanism of the MXene sensor was explained. The proposed monitoring method based on the MXene sensor is suitable for the health monitoring of adhesive rivet hybrid connection structures under tensile‐compression, impact, and vibration conditions. Highlights: MXene sensors can be integrated into composite hybrid bonded‐riveted joints without defects.MXene sensors combined with flexible circuits can form a high‐stability monitoring array.Monitor the mechanical behavior of bonded and riveted areas by the resistance change rate of MXene sensors.Real‐time monitor the micro damage and acceleration changes under the vibration environments. [ABSTRACT FROM AUTHOR]

Simple Summary: The Platycladus orientalis is a coniferous gymnosperm tree species widely distributed in China and the fFar east of Russia. It has been widely introduced and cultivated in East and South Asia. Plant abscisic acid increases and affects stomatal behavior during soil drought, and prolonged drought-induced stomatal closure definitely affects the soluble sugar content of plants. We found significant correlations between gas exchange and abscisic acid content, as well as the soluble sugar content of Platycladus orientalis under different moisture conditions, as a result of increased drought stress in Platycladus orientalis due to ongoing global climate change. This helps us to reveal the mechanism of plant adaptation to drought–rehydration under different drought treatments. To uncover the internal mechanisms of various drought stress intensities affecting the soluble sugar content in organs and its regulation by endogenous abscisic acid (ABA), we selected the saplings of Platycladus orientalis, a typical tree species in the Beijing area, as our research subject. We investigated the correlation between tree soluble sugars and endogenous ABA in the organs (comprised of leaf, branch, stem, coarse root, and fine root) under two water treatments. One water treatment was defined as T1, which stopped watering until the potted soil volumetric water content (SWC) reached the wilting coefficient and then rewatered the sapling. The other water treatment, named T2, replenished 95% of the total water loss of one potted sapling every day and irrigated the above-mentioned sapling after its SWC reached the wilt coefficients. The results revealed that (1) the photosynthetic physiological parameters of P. orientalis were significantly reduced (p < 0.05) under fast and slow drought processes. The photosynthetic physiological parameters of P. orientalis in the fast drought–rehydration treatment group recovered faster relative to the slow drought–rehydration treatment group. (2) The fast and slow drought treatments significantly (p < 0.05) increased the ABA and soluble sugar contents in all organs. The roots of the P. orientalis exhibited higher sensitivity in ABA and soluble sugar content to changes in soil moisture dynamics compared to other organs. (3) ABA and soluble sugar content of P. orientalis showed a significant positive correlation (p < 0.05) under fast and slow drought conditions. During the rehydration stage, the two were significantly correlated in the T2 treatment (p < 0.05). In summary, soil drought rhythms significantly affected the photosynthetic parameters, organ ABA, and soluble sugar content of P. orientalis. This study elucidates the adaptive mechanisms of P. orientalis plants to drought and rehydration under the above-mentioned two water drought treatments, offering theoretical insights for selecting and cultivating drought-tolerant tree species. [ABSTRACT FROM AUTHOR]

The composite bolted joints are the weak points of overall structure, lacking an effective and accurate monitoring method. In this paper, a novel MXene/CNTs film sensor with high sensitivity and stability was synthesized for the damage evolution monitoring of composite bolted joints. The correlation between the response signals of the sensors and the mechanical behaviors of the composite structures is established. Based on this research, the damage evolution monitoring and failure level evaluation of composite bolted joints were studied. The damage properties of the composite bolted joints can be reflected in real‐time by the resistance change rates of the sensors. The experimental results show that the failure level of composite bolted joints can be divided into four levels (I‐II‐III‐IV) according to the resistance change rates of sensors. Especially when the damage extended to the III stage, the ∆R/R0 surged from 0.3 to 0.75. The time point of this step signal occurred about 1 min earlier than the time point of max bearing strength, which can effectively warn the occurrence of structural failure. Highlights: Research used high‐sensitivity MXene/CNTs sensor to monitor bolt structureSensor array can be integrated with the composite bolted structureStructural damage of composite bolted joints was accurately monitoredFailure level evaluation of composite bolted structure was achieved [ABSTRACT FROM AUTHOR]

Al-Bi immiscible alloys, as wear resistance material, have attracted increasing attention in the past. The solidification processing of alloys plays a significant role in the final solidification microstructure and properties of immiscible alloys. Here, we present a strategy to produce a homogeneous microstructure in Al-Bi alloys based on intermetallic compounds. With the addition of Sm and Ti, the effect on the microstructure and properties was discussed in detail. The Al-Bi-Sm-Ti alloys achieve high self-lubricating performance, referring to the values of the coefficient of friction and wear rate. The intermetallic compounds formed were regarded as the main anti-friction and anti-wear factors. The results of numerical simulation indicate that microsegregation in Al-Bi alloys was retarded based on the intermetallic compounds. The coefficient of friction of the Al-Bi-1Sm-2Ti alloy was 46.2% lower than that of the Al-Bi alloys at 300 m. This research provides a new perspective and guidance for designing and fabricating composites with superior self-lubricating properties. [ABSTRACT FROM AUTHOR]

To explore whether there were differences among the patterns of response of grasslands with different levels of degradation to extreme drought events and nitrogen addition, three grasslands along a degradation gradient (extremely, moderately, and lightly degraded) were selected in the Bashang area of northern China using the human disturbance index (HDI). A field experiment with simulated extreme spring drought, nitrogen addition, and their interaction was conducted during the growing seasons of 2020 and 2021. The soil moisture, aboveground biomass, and composition of the plant community were measured. The primary results were as follows. (1) Drought treatment caused soil drought stress, with moderately degraded grassland being the most affected, which resulted in an 80% decrease in soil moisture and a 78% decrease in aboveground biomass. The addition of nitrogen did not mitigate the impact of drought. Moreover, the aboveground net primary production (ANPP) in 2021 was less sensitive to spring drought than in 2020. (2) The community composition changed after 2 years of drought treatment, particularly for the moderately degraded grasslands with annual forbs, such as Salsola collina, increasing significantly in biomass proportion, which led to a trend of exacerbated degradation (higher HDI). This degradation trend decreased under the addition of nitrogen. (3) The variation in drought sensitivities of the ANPP was primarily determined by the proportion of plants based on the classification of degradation indicators in the community, with higher proportions of intermediate degradation indicator species exhibiting more sensitivity to spring drought. These findings can help to provide scientific evidence for the governance and restoration of regional degraded grassland under frequent extreme weather conditions. [ABSTRACT FROM AUTHOR]

Composite structures are sensitive to impact damage in practical engineering. Electric resistance change method (ERCM) is an ideal technique for damage monitoring of composite structures. Due to the anisotropy of fiber-resin matrix composites, impact location monitoring is difficult, and research on impact location of fiber composite laminates (FRPs) is limited. A preparation method of MXene/CNT/CuNps thin film sensor is proposed. According to the modeling simulation and theoretical calculation, the resistance change characteristics of the thin film sensor are obtained, the relationship between the impact distance and the resistance change is established, and the sensor array is designed. A three-point localization algorithm and a weight function compensation localization algorithm are proposed, which can improve the imaging accuracy of the impact position. The impact point location was observed and analyzed using ultrasonic C-scan technology. The results show that the weight function compensation positioning algorithm can accurately locate the impact of the composite structure, and the error in the X direction is 7.1%, the error in the Y direction is 0.03%, which verifies the effectiveness of the method. [ABSTRACT FROM AUTHOR]

Flexible piezoelectric pressure sensors have a great application prospect in wearable electronic products due to the advantages of low cost, fast response speed and a self-powered system. However, traditional films based on piezoelectric ceramic/polymer materials face problems such as poor dispersion and insufficient polarization, which hinder the piezoelectric performance of pressure sensors. In this work, MXene was introduced to modify the surface of barium titanate (BaTiO3), which was blended with poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) matrix. An electrospinning method was adapted to fabricate BaTiO3/MXene/PVDF-TrFE composite films. This work proposed a new microscopic sensing mechanism. In addition, this MXene-modification strategy could improve the dispersion of BaTiO3 into the PVDF-TrFE matrix, increase the polarization efficiency and enhance the piezoelectric performance of the sensors. The results showed that the composite film with 0.15 wt% MXene could achieve a remarkable output voltage of 7.6 V. In addition, the tensile strength of the composite film with 0.15 wt% MXene (20.8 MPa) was 77.8% higher than that without MXene (11.7 MPa). Meanwhile, the β phase content of the composite film could reach 81.04%, and the crystallinity increased from 39.49% to 50.31%. The fabricated piezoelectric pressure sensor had a wide detection range (0.2–400 kPa) and a short response time (56 ms). Besides, even after undergoing over 5000 compression cycles, it maintained a stable piezoelectric response. This pressure sensor could quickly respond to joint movements and strenuous exercises in humans. Therefore, this pressure sensor showed great advantages and potential in the application of human motion monitoring. [ABSTRACT FROM AUTHOR]

More and more studies have shown that Branched chain amino acid transaminase 1 (BCAT1) is involved in the occurrence and development of a variety of tumors. However, the mechanism of its occurrence and development in hepatocellular carcinoma (HCC) remains unclear. Here, we demonstrated the relationship between BCAT1 and AKT signaling pathway, as well as EMT, and the clinical significance of BCAT1 by using BCAT1 expression in 5 cell lines and 113 liver cancer and non-liver cancer tissue samples. The results showed that the expression of AKT was positively correlated with BCAT1 in HCC tissues, and BCAT1 could promote the progression of HCC cells through the AKT signaling pathway. Clinical analysis and Bioinformatics technology analysis revealed that BCAT1 was correlated with poor prognosis, and BCAT1 expression in the HCC tissues was evidently correlated with tumor number, vascular invasion, Edmondson grade and TNM stage (P < 0.05). In vitro studies showed that BCAT1 increased the invasion and migration of in MHCC-97H cells a d Huh7 cells. By inhibiting the expression of the BCAT1 gene, we detected the corresponding changes in the expression levels of Twist, E-cadherin and Vimentin, confirming that BCAT1 may promote the invasion and migration of HCC cells through epithelial-mesenchymal transformation (EMT). Overall, BCAT1 can activate AKT signaling pathway and EMT to promote the development and metastasis of HCC cells. this study may provide new ideas and directions for cancer diagnosis and treatment. [ABSTRACT FROM AUTHOR]

With the increasing application of composite materials in the industry, the repair of damaged composite materials has gradually become a research focus. In this article, the traditional scarf repairing laminate was stitched with carbon fiber line to check the influence of stitch on repair efficiency. The traditional Buckypaper sensors and the novel MXene sensors were used to conduct real‐time structural health monitoring of the specimen, and the results were compared with X‐ray monitoring. The experimental results show that the breaking strength of the stitch repaired specimen is 21.2% higher than that of the traditional scarf repaired specimen. Both kinds of sensors can monitor the load of the specimen in real‐time. As the force is transferred, the resistance change rate (∆R/R0) of the Buckypaper sensors varies by up to 0.045, while the ∆R/R0 of the MXene sensors varies by up to 0.7. The resistance change of the sensors can also reflect the initiation of damage. The sudden change in ∆R/R0 of 0.01 can be monitored on the specimen in the crack initiation stage. Through the X‐ray nondestructive testing method, it can be confirmed that both kinds of sensors are suitable for structural health monitoring, and the sensitivity of the MXene sensors is much higher. [ABSTRACT FROM AUTHOR]

To explore the typical alkyltrichlorosilane and optimal volume ratio of the alkyltrichlorosilane-toluene solutions for preparing superhydrophobic Pinus kesiya wood, four alkyltrichlorosilanes: methyltrichlorosilane (MTCS), butyltrichlorosilane (BTCS), dodecyltrichlorosilane (DTCS), and octadecyltrichlorosilane (OTCS) were each used to modify the wood samples at different volume ratios of alkyltrichlorosilane-toluene solutions. The Pinus kesiya wood specimens were immersed in the solutions to fabricate superhydrophobic coatings on the wood surface. The wettability of the modified wood surfaces was characterized by water contact angle and water uptake values. The chemical composition of the wood samples was analyzed using X-ray photoelectron spectroscopy (XPS) and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), and the surface morphology of the modified wood samples was observed using scanning electron microscopy (SEM). The result showed that all types of alkyltrichlorosilane-modified wood changed from hydrophilic to hydrophobic. The wood specimens had the highest water contact angle of 151.8 ± 0.4° and lowest water uptake of 18 ± 0.6 wt.% when 0.25 vol.% MTCS and 0.25 vol.% OTCS solutions were applied, respectively. [ABSTRACT FROM AUTHOR]

Composite laminates are susceptible to impact damage during service, and some damage is invisible. So it is necessary to monitor the impact location on the surface of composite laminates. Novel carbon nanomaterials represented by carbon nanotubes and MXene films have unique nanoscale structures and excellent physical properties. Applying the carbon nanotubes (CNT) and MXene films to monitoring the damage area of composite laminates under impact. Laying sensor arrays within the monitoring range, a localization algorithm suitable for sensor arrays is proposed, which can accurately calculate and locate the impact position to the monitoring area. Then check the impact location area, detect damage in time, and avoid structural damage or even failure caused by accumulated damage. After the impact test, the sum of the resistance change rate of the sensor in the M5 area is 0.6030, which is higher than the sum of the resistance change rate of other areas, and the impact point is determined to be in the M5 area. The calculation results are completely consistent with the real impact area, which greatly improves the efficiency of detection and maintenance, and has certain engineering significance. [ABSTRACT FROM AUTHOR]

Recently, owing to the high theoretical capacity and safety, zinc-ion energy storage devices have been known as one of the most prominent energy storage devices. However, the lack of ideal electrode materials remains a crucial hindrance to developing zinc-ion energy storage devices. MXene is an ideal electrode material due to its ultra-high conductivity, particular sheet structure and unique physical and chemical properties, and it has shown excellent performance in practical applications. Therefore, this review briefly introduces the basic information about MXenes and details the applications of MXene in zinc-ion batteries and zinc-ion hybrid capacitors in recent years. Finally, the application characteristics of MXene in zinc-ion energy storage devices are summarized and an outlook is given. This paper highlights the features and advantages of zinc-ion energy storage devices more by comparing them with other energy storage devices, to provide a comprehensive reference for scholars in this field. [ABSTRACT FROM AUTHOR]

High‐performance electrode materials are the key to advances in the energy storage area. 2D transition metal carbide Ti3C2TX is the most widely studied MXene with a unique two‐dimensional structure, exhibiting excellent electrochemical properties and becoming a new choice electrode material for supercapacitors in many studies However, the poor mechanical properties of pure the Ti3C2TX film has become the bottlenecks for the application. Ti3C2TX with less Li+ was prepared by proton acid colloid treatment, and then the single‐walled carbon nanotubes (SWCNTs) were used as interlayer barriers in the films to prevent Ti3C2TX layers from restacking to prepare Ti3C2TX and SWCNTs composite films. The composite films were tested and analyzed by different electrochemical techniques. The results showed that the film formed by MXene colloidal filtration after proton acid treatment was denser and the electrical conductivity reached 608700 S/m, which was 3.2 times higher than that of the original Ti3C2TX film. The composite film was prepared by mixing MXene colloidal proton acid treatment and SWCNTs, followed by filtration showd good capacitive capacity, reaching 270.5 F/g by testing in the 1 m H2SO4 electrolyte with the CV cycle of 5 mV/s. And the specific capacitance retention reaches 97.6 % under 5000 CV cycles. The tensile test of composite film shows that the ultimate strength up to 50.3 MPa, which is about 2.3 times compared to original Ti3C2TX film. [ABSTRACT FROM AUTHOR]

In this paper, a method with highly sensitive multi-wall carbon nanotubes (MWCNTs) film sensors was put forward to evaluate the health condition of glass fiber-reinforced composite single lap joints in real time. With this method, the single lap joint fracture can be predicted when the resistance change rate reached 1.11% to 5.89% approximately. Meanwhile, for the single lap joints, the reality can be found that the farther distance was from the interface to different layers, the more easily defect might emerge under the force introduced in the interface plane. And the stress in the middle area of the interface for the joint was greater than that in the edge when it was stretched. The results of experiments indicated that the effectiveness of MWCNTs sensors to monitor the health condition of the single lap joints was confirmed. [ABSTRACT FROM AUTHOR]

This paper prepares a flexible MXene/CNT film by layer‐by‐layer (LbL) self‐assembly process. Based on excellent conductivity and good compatibility with resin, MXene/CNT can be used for on‐line monitoring of large and complex liquid composite molding (LCM). In this paper, the MXene/CNT will be used as a novel micro‐nano sensor. The MXene/CNT sensor is embedded between the sandwich layers of the sandwich composite structure. The resistance information of the MXene/CNT sensor was collected by online monitoring system during LCM. The tube cross‐linked network's conductive model will be established to reveal the resistance response sensing mechanisms of MXene/CNT sensors and the response rules of resin flow states and resistance signals. Using the real‐time monitoring information collected by the MXene/CNT sensor, combined with Darcy's law, the comparison results of different permeability are obtained. The monitoring results show that polyvinyl chloride (PVC) interlayer significantly influences the resin flow trend and penetration of the core layer. Simultaneously, the interlayer's presence will also affect the resin flow trend and penetration of the lower layer of the PVC sandwich layer. The research results will provide theoretical guidance and technical support for designing process parameters and in situ real‐time monitoring of LCM in the engineering industry. [ABSTRACT FROM AUTHOR]

Multi-component composite can effectively improve the electromagnetic interference shielding effectiveness (EMI SE) due to the synergistic effects. Herein, graphene aerogel (GA) provides a three-dimensional network framework and in situ generation of titanium dioxide (TiO2) on its network layer by the sol–gel method. After microwave irradiation reduction, the titanium dioxide/microwave-reduced GA (TiO2/MRGA) was immersed in epoxy resin solution and cured to obtain its composite. The existence of the Ti–O–C bond proves the favorable combination of TiO2 and MRGA. Under electromagnetic radiation, MRGA and TiO2 generate a synergistic effect to improve the EMI SE of the composite. When the mass ratio of TiO2 to MRGA is 1.5:1 (2.1 wt%+1.4 wt%), the composite exhibits a maximum EMI SE of 32.5 dB in the X band. Moreover, when the mass ratio of TiO2 to MRGA is in the range of 1 to 1.8, the average EMI SE of the composites increases by 37% compared with that of the MRGA/Epoxy composite. The research indicates that this kind of EMI shielding composite has enormous application potential. [ABSTRACT FROM AUTHOR]

Composite pressure vessels (COPV) are widely used in the aerospace field, where they experience a wide range of unpredictable operating conditions. However, the recent work remains at monitoring the structural health of the whole COPV without considering lamination. This article introduces a kind of buckypaper (BP) sensor that can be put into COPV for structural health monitoring without requiring their removal from service. Simultaneously, the introduction of a flexible printed circuit enables the omnidirectional BP sensor to monitor strain state changes in two directions at one time. It can also form a matrix monitoring area with fewer sensors and increase the survival rate. Before being applied to COPV, tensile experiments and fatigue cycle experiments were carried out. At hydraulic pressure tests, the BP sensor is embedded in the COPV to perform real-time strain monitoring in both the bile layer and fiber layer. The experimental result shows that the BP sensor can maintain a good response and response consistency for a long time. Therefore, the BP sensor can be used for health monitoring of COPV. [ABSTRACT FROM AUTHOR]

Repair of composite materials is an important cost savings for the aviation industry, and it is also very important to monitor the repaired structure. In this paper, a novel micro-nano sensor which is combined with Flexible Printed Circuit and Buckypaper (BP) sensor is introduced, and has the characteristics of multidirectional, real time and high sensitivity. These sensors are used to monitor the strain at different positions on the composite repair structure. The piezoresistive response of BP sensor is obtained and the main working mechanism of BP sensor is explained. Experiments show that this sensor can preliminarily judge the damage position and degree of the repaired structure, and monitor whether it reaches the strength limit. And it can judge the loading history of the structure. This ensures the safety of the repaired structure in the process of continuous service to a certain extent. [ABSTRACT FROM AUTHOR]

Plant phenological responses under global climate change is a hot topic in current ecological research. However, it also has comprehensive interactions with other anthropogenic environmental factors including nitrogen (N) enrichment owing to atmospheric deposition and fertilization, and grassland degradation, which attracts less attention. Continuous photographic techniques enabled us to monitor the plant cover dynamics and extract the phenophases (start, end, length and the peak cover position of growing season) in a field experimental platform with six N treatment levels on five grasslands along a degradation gradient indicated by a human disturbance index (HDI). The results showed that N addition significantly promoted seasonal plant covers of degraded grasslands, while mature grassland responding less sensitively. Moreover, increasing rates during spring green‐up and decreasing rates during autumn senescence were promoted by N addition, while those of grasslands with lower degradation levels showed non‐linear saturation patterns. Phenophases at the community level were generally insensitive to N addition, with the most degraded grassland (totally degraded grassland, TD) and mature grassland (MG) responding significantly. The length of growing season of TD was shortened by 8 days and that of MG lengthened by 15 days on average from N addition. The responses of extracted phenophases were regulated more by the proportions of three groups of degradation indicators (annuals, moderate grazing degradation indicator species, and climax species) than those of grasses and forbs. Our findings highlight the relationship between community phenology and grassland degradation, which can benefit the assessment and restoration of degraded grasslands in semiarid regions. [ABSTRACT FROM AUTHOR]

Intravascular ultrasound (IVUS) has become a useful tool in the detection of coronary artery disease. However, non-uniform rotation distortion (NURD) reduces the image quality. In order to suppress the influence of NURD, a piezoelectric motor that can meet the requirements of IVUS catheters has been proposed. The motor has a diameter of 1 mm and a length of 10 mm using the new polarization direction proposed in the paper. A 45° mirror is fixed on the top of the motor to reflect the ultrasound transmitted from the transducer. The manufacture and drive of the piezoelectric motor is simple, and the maximum speed of the piezoelectric motor can reach 6450 rpm under the voltage of 20Vp-p. The minimum power required by the rotating motor is only 0.038 W, which can be directly driven by the signal generator without a power amplifier. The motor can operate at a low voltage and still has a high and stable speed. Meanwhile, the speed of the motor is controllable and has a satisfactory stability with a maximum angular error of 8°. The images detected by the cooperation of the motor and the ultrasonic transducer are also shown, which indicates that the motor has the rotational stability that meets the imaging requirements and the potential for application in the IVUS catheter to help improve the image quality of the coronary arteries and prevent and help treat potential diseases. [ABSTRACT FROM AUTHOR]

High temperatures induce early bolting in lettuce (Lactuca sativa L.), which decreases both quality and production. However, knowledge of the molecular mechanism underlying high temperature promotes premature bolting is lacking. In this study, we compared lettuce during the bolting period induced by high temperatures (33/25 °C, day/night) to which raised under controlled temperatures (20/13 °C, day/night) using iTRAQ-based phosphoproteomic analysis. A total of 3,814 phosphorylation sites located on 1,766 phosphopeptides from 987 phosphoproteins were identified after high-temperature treatment,among which 217 phosphoproteins significantly changed their expression abundance (116 upregulated and 101 downregulated). Most phosphoproteins for which the abundance was altered were associated with the metabolic process, with the main molecular functions were catalytic activity and transporter activity. Regarding the functional pathway, starch and sucrose metabolism was the mainly enriched signaling pathways. Hence, high temperature influenced phosphoprotein activity, especially that associated with starch and sucrose metabolism. We suspected that the lettuce shorten its growth cycle and reduce vegetative growth owing to changes in the contents of starch and soluble sugar after high temperature stress, which then led to early bolting/flowering. These findings improve our understanding of the regulatory molecular mechanisms involved in lettuce bolting. [ABSTRACT FROM AUTHOR]

In this work, graphene aerogels (GAs) with three-dimensional interconnected networks were prepared by chemical reduction and self-assembly of graphene oxide sheets. After microwave treatment, obtained microwave reduced graphene aerogels (MRGAs) were used in the preparation of bismaleimide (BMI) composites. The results show that the microwave treatment significantly enhanced the quality of GAs, and the three-dimensional networks in the GAs were well retained. Moreover, the MRGAs were highly efficient in endowing BMI with high electrical conductivity and excellent electromagnetic interference shielding effectiveness (EMI SE). The conductivity of MRGA/BMI composites was 42–68% higher than that of GA/BMI composites. When the filler content is 1.6 wt.%, the EMI SE of MRGA/BMI composite was 32.3% higher than that of GA/BMI composite in the X band. A facile approach to enhance the quality and conductivity of graphene aerogels (GAs) by microwave irradiation was reported. The obtained microwave reduced graphene aerogels (MRGAs) endowed the MRGA/bismaleimide (BMI) composites with high conductivity and electromagnetic interference (EMI) shielding performance. Moreover, the MRGA/BMI composites showed an EMI shielding mechanism dominated by absorption. [ABSTRACT FROM AUTHOR]

In this study, a novel sensor with high sensitivity and linear was prepared based on two-dimensional (2D) material (MXene) and ink, which can be used for deformation and damage monitoring of structural composites. The MXene was efficiently prepared by etching Ti3AlC2 powder with LiF–HCl solution and subsequent vacuum drying. The viscosity and adhesion of MXene/ink composites were controlled by changing the ratio of solvent (dimethyl sulfoxide) to ink. The MXene/ink was printed on the surface of the composite material to avoid forming defects in the composite material. The percolation threshold of the MXene/ink nanocomposite was relatively low, 3.6wt%. In this paper, MXene/ink composites with different contents were selected as the sensor, and the characteristics of the sensor were verified through monotone stretch and cyclic load-and-unload tests. When the MXene content just exceeds the percolation threshold (4wt%), the gauge factor (GF) of the sensor is higher, the results of monotonic tensile experiment show that there are two different sensitive stages of linear change (0 ~ 0.477%) and (0.477 ~ 1.37%), and the range GF is116.6 and 554.3, respectively. In addition, the linear relationship and sensitivity of the sensor remained stable after loading and unloading tensile tests. MXene/ink sensor has a broad application prospect in damage monitoring of aerospace structural composites. [ABSTRACT FROM AUTHOR]

In this study, a rubber composite was prepared based on two-dimensional (2D) material (MXene) and ethylene propylene diene rubber (EPDM). The MXene was efficiently prepared by etching Ti3AlC2 powder with LiF-HCl solution and subsequent vacuum drying, and the dispersion of MXene in EPDM was improved by optimizing the grinding process, ultrasonic stripping and stirring method. In the process of exploring the electrical conductivity of this material system, the composite exhibits low percolation threshold of 2.7 wt%, a high conductivity of 106 Sm−1 and superior thermal conductivity of 1.57 W/m K at the MXene content of 6 wt%. In addition, MXene (6 wt%)/EPDM with 0.3-mm thick exhibits an EMI shielding performances (SE) up to 48 dB in the X-band (8.2–12.4 GHz) and 52 dB in the Ku-band (12.4–18 GHz) (SE) which are much better than the electromagnetic shielding properties of other rubber blends, and these properties indicate MXene/EPDM composite has great potential for versatile applications. [ABSTRACT FROM AUTHOR]

It remains challenging to prepare wearable strain and pressure sensors with excellent mechanical properties, ultra‐high flexibility and sensitivity. Electrically conductive graphene platelets (GnPs) with high structural integrity are used in making a composite film fabricated using robust fabrication techniques. The gauge factor for the strain is up to 100 at 0%‐5% strain and 50 at 5%‐30% strain, and the sensitivity to pressure is 2.7×10‐2 kPa‐1 between 0 and 10 kPa and 1.5×10‐4 kPa‐1 between 300 and 1000 kPa. In addition, the flexible sensor demonstrates good repeatability and durability after 1000 cycles of tensile and compression tests. The flexible sensor has fast response ability and a wide operating temperature range, suggesting the excellent response to temperature. The flexible sensor is applied in monitoring several human motions as a wearable device with high accuracy. The ability to detect strain, pressure and temperature of the flexible sensor extends its applications to multifunctional wearable devices. [ABSTRACT FROM AUTHOR]

An innovative sandwich battery composite was designed and manufactured by applying he vacuum assisted hand lay-up molding process. A series of bending mechanical properties and electrical performance testing were performed to investigate the reliability of the structure-battery composites. Experimental results showed that embedding the lithium polymer cell had no influence on the specific strength of the composite components and the electrical properties of the battery packs. Moreover, the charging and discharging properties of the structure-battery composites were not affected when subjected to 60% of failure load level or less. Under 80% of failure load, the charging and discharging capacities of the battery were reduced by 21.80% and 22.78%, respectively, and this degradation was unrecoverable. The structure-battery system has great potential as a multifunctional composite to optimize structural design and improve lightweight integrated properties. [ABSTRACT FROM AUTHOR]

This work developed a facile approach to fabricate highly sensitive and flexible polyurethane/graphene platelets composite film for wearable strain sensor. The composite film was fabricated via layer-by-layer laminating method which is simple and cost-effective; it exhibited outstanding electrical conductivity of 1430 ± 50 S/cm and high sensitivity to strain (the gauge factor is up to 150). In the sensor application test, the flexible strain sensor achieves real-time monitoring accurately for five bio-signals such as pulse movement, finger movement, and cheek movement giving a great potential as wearable-sensing device. In addition, the developed strain sensor shows response to pressure and temperature in a certain region. A multifaceted comparison between reported flexible strain sensors and our strain sensor was made highlighting the advantages of the current work in terms of (1) high sensitivity (gauge factor) and flexibility, (2) facile approach of fabrication, and (3) accurate monitoring for body motions. [ABSTRACT FROM AUTHOR]

This study develops a facile approach to fabricate adhesives consists of epoxy and cost-effective graphene platelets (GnPs). Morphology, mechanical properties, electrical and thermal conductivity, and adhesive toughness of epoxy/GnP nanocomposite were investigated. Significant improvements in mechanical properties of epoxy/GnP nanocomposites were achieved at low GnP loading of merely 0.5 vol%; for example, Young's modulus, fracture toughness (K1C) and energy release rate (G1C) increased by 71%, 133% and 190%, respectively compared to neat epoxy. Percolation threshold of electrical conductivity is recorded at 0.58 vol% and thermal conductivity of 2.13 W m−1 K−1 at 6 vol% showing 4 folds enhancements. The lap shear strength of epoxy/GnP nanocomposite adhesive improved from 10.7 MPa for neat epoxy to 13.57 MPa at 0.375 vol% GnPs. The concluded results are superior to other composites or adhesives at similar fractions of fillers such as single-walled carbon nanotubes, multi-walled carbon nanotubes or graphene oxide. The study promises that GnPs are ideal candidate to achieve multifunctional epoxy adhesives. [ABSTRACT FROM AUTHOR]

As the portable device hardware has been increasing at a noticeable rate, ultrathin flexible materials with the combination of high thermal conductivity and excellent electromagnetic interference (EMI) shielding performance are urgently needed. Here, we fabricated ethylene propylene diene monomer rubber with different loading graphene nanoplatelets (GnPs/EPDM) by a cost-efficient approach, which combines mixing, ultrasonication and compression. Further investigation demonstrates that the 8 wt.% GnPs/EPDM with only 0.3 mm in thickness shows excellent electrical conductivity (28.3 S/m), thermal conductivity (0.79 W/m K) and good mechanical properties. Besides, the 8 wt.% GnPs/EPDM exhibits an EMI shielding effectiveness (SE) up to 33 dB in the X-band (8.2–12.4 GHz) and 35 dB in the Ku-band (12.4–18 GHz), superior to most of the reported rubber matrix. Additionally, the GnPs/EPDM shows excellent flexibility and stability with 95% and 94% retention of EMI SE even after repeated bending for 5000 times and corrosion (under 5% NaCl environment) for a week. Our flexible EMI shielding material will benefit the fast-growing next-generation commercial portable flexible electrons. The GnPs/EPDM was fabricated by a cost-efficient approach, which combines mixing, ultrasonication and compression. The prepared 8 wt.% GnPs/EPDM shows excellent electrical conductivity (28.3 S/m), thermal conductivity (0.79 W/m.K) and good mechanical properties. Besides, the SET reaches up to 33 dB in the X-band (8.2–12.4 GHz) and 35 dB in the Ku-band (12.4–18 GHz) with the thickness of only 0.3 mm. The flexible EMI shielding material will benefit the fast growing next-generation commercial portable flexible electrons. [ABSTRACT FROM AUTHOR]

A novel, omnidirectional, nanomaterial-based sensor technology which can provide wide area damage detection of composite structures was proposed in this work. The behaviors of the buckypaper sensors subjected to both tensile and low-velocity impact were investigated. The experimental results showed that the rectangle buckypaper sensor has a large range of sensing coefficients from 21.40 to 35.83 at different directions under tensile. However, the circular buckypaper sensor has a steady sensing coefficient of about 155.63. Thus, the circular buckypaper sensor as a kind of omnidirectional sensor was chosen to monitor the impact damage. The low-velocity impact damage of composite structures is characterized by the gauge factor of omnidirectional buckypaper sensors and the results of C-scanning. Omnidirectional buckypaper sensors' electrical resistance increases with repeated impact loading; composite structure elastic deformation and damage evolution can be identified from resistance change. Experiment results show that structure monitoring based on the omnidirectional buckypaper sensor not only can detect small barely visible impact damage flaws and the damage evaluation of composite structures subjected to impact but also can determine the location of low-velocity impact damage through the analysis of results. Through comparison with C-scan, the results have preliminarily demonstrated that the omnidirectional carbon nanotubes' buckypaper sensor can serve as an efficient tool for sensing the evolution of impact damage as well as serve structural health monitoring of composite structures. [ABSTRACT FROM AUTHOR]

A novel, omnidirectional, nanomaterial-based sensor technology which can provide wide area damage detection of composite structures was proposed in this work. The behaviors of the buckypaper sensors subjected to both tensile and low-velocity impact were investigated. The experimental results showed that the rectangle buckypaper sensor has a large range of sensing coefficients from 21.40 to 35.83 at different directions under tensile. However, the circular buckypaper sensor has a steady sensing coefficient of about 155.63. Thus, the circular buckypaper sensor as a kind of omnidirectional sensor was chosen to monitor the impact damage. The low-velocity impact damage of composite structures is characterized by the gauge factor of omnidirectional buckypaper sensors and the results of C-scanning. Omnidirectional buckypaper sensors' electrical resistance increases with repeated impact loading; composite structure elastic deformation and damage evolution can be identified from resistance change. Experiment results show that structure monitoring based on the omnidirectional buckypaper sensor not only can detect small barely visible impact damage flaws and the damage evaluation of composite structures subjected to impact but also can determine the location of low-velocity impact damage through the analysis of results. Through comparison with C-scan, the results have preliminarily demonstrated that the omnidirectional carbon nanotubes' buckypaper sensor can serve as an efficient tool for sensing the evolution of impact damage as well as serve structural health monitoring of composite structures. [ABSTRACT FROM AUTHOR]

Highly flexible, mechanically robust and ultra-thin Ni deposited onto multi-walled carbon nanotubes (MWCNTs) buckypapers (BPs) were fabricated via vacuum filtration and magnetron sputtering. The samples were characterized structurally using scanning electron microscopy and X-ray Diffraction. Electromagnetic interference (EMI) shielding effectiveness (SE) of Ni deposited onto MWCNTs BPs with different deposition time (0, 30 and 60 min) were tested in frequency range of 2-18 GHz, including S-band, C-band, X-band and Ku-band. The 60 min Ni deposited onto MWCNTs BPs exhibited much higher EMI SE of average value up to 42.59 dB with the thickness of only 0.105 mm. Based on reliability study, the 60 min Ni deposited onto MWCNTs BPs retains 94.3% of its EMI SE after 500 cycles of mechanical bending. Therefore, the results and techniques promise a simple and effective approach to achieve light-weight and ultra-thin composite films for a wide application at the prospect of the field of EMI shielding. [ABSTRACT FROM AUTHOR]

Ultrathin multi-walled carbon nanotubes (MWCNTs) buckypapers inserted with Mn nanopowder were fabricated via vacuum filtration method, at a lower manufacturing cost and easier operation. The buckypapers were characterized structurally using scanning electron microscopy, energy-dispersive spectrometer and X-ray diffraction. Electromagnetic interference (EMI) shielding effectiveness (SE) of MWCNTs buckypapers inserted with Mn nanopowder (0–30wt.%) were tested in X-band (8.2–12.4GHz). When the blended Mn nanopowder content is 20wt.%, the buckypaper exhibits much higher EMI SE of average value up to 42dB with the thickness of only 0.11mm. Further, this buckypaper is flexible and lightweight, and can be integrated with resin matrix composites. Thus, the results and techniques promise a simple and effective approach to achieve lightweight and ultrathin composite films for a wide application prospect in the field of EMI shielding and microwave absorption. Ultra-thin multi-walled carbon nanotubes (MWCNTs) buckypapers inserted with Mn nanopowder were fabricated via vacuum filtration method, at a lower manufacturing cost and with easier operation. The buckypaper exhibited much higher EMI SE of average value up to 42dB with the thickness of only 0.11mm. Further, this buckypaper is flexible, lightweight and can be integrated with resin matrix composites. [ABSTRACT FROM AUTHOR]

Abstract: This work aims to assess the effect of maleic anhydride functionalized graphene oxide (MAH‐f‐GO) on the interfacial properties of carbon fibre/bismaleimide (BMI) composites by experimental and finite element (FE) methods. Transverse fibre bundle (TFB) specimens with different contents of MAH‐f‐GO nanoparticles were manufactured to investigate the interfacial strength of the carbon fibre/BMI composites. The fracture surface of the TFB specimens was examined by scanning electron microscopy to observe the morphologies of the fibre − matrix interface. The coefficient of thermal expansion, cure shrinkage and elastic modulus were measured and included in the FE simulation. An FE analysis model was established to simulate the thermal residual stress distribution around the carbon fibre and to estimate the interfacial bonding strength of the TFB specimens. The combination of experimental and FE analysis results indicated that the addition of MAH‐f‐GO nanoparticles noticeably reduced the concentration of residual stress at the fibre − matrix interface and enhanced the interfacial properties of the carbon fibre/BMI composites.© 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Hollow glass microspheres (HGMs) double-coated with Co-Ni/FeO composite has been successfully prepared by electroless plating and coprecipitation method, which is applied to the microwave absorption materials. The surface morphology, structure, magnetism, electromagnetic property of the products have been characterized by scanning electron microscope, X-ray diffraction, vibrating sample magnetometer and vector network analyzer, respectively. The results show that the outer surfaces of HGMs were coated by continuous and uniform layers of Co-Ni/FeO. The maximum magnetization and coercivity values of HGMs/Co-Ni/FeO composite increase to 19.46 emu/g and 505 Oe, with a maximum applied magnetic field of 10 kOe. The dielectric loss and magnetic loss of the composite increase remarkably in the frequency range of 1-18 GHz. The maximum microwave reflection loss could reach −35.4 dB at 6.7 GHz (C-band) with 1.81 GHz bandwidth below −10 dB. [ABSTRACT FROM AUTHOR]

Due to the importance and complexity of photo assimilate transport in raffinose family oligosaccharide (RFO)-transporting plants such as melon, it is important to study the features of the transport structure (phloem) particularly of the lateral branches connecting the source leaves and the sink fruits, and its responses to environmental challenges. Currently, it is unclear to what extents the cold environmental temperature stress would alter the phloem ultrastructure and RFO accumulation in RFO-transporting plants. In this study, we firstly utilized electron microscopy to investigate the changes in the phloem ultrastructure of lateral branches and RFO accumulation in melons after being subjected to low night temperatures (12°C and 9°C). The results demonstrated that exposure to 9°C and 12°C altered the ultrastructure of the phloem, with the effect of 9°C being more obvious. The most obvious change was the appearance of plasma membrane invaginations in 99% companion cells and intermediary cells. In addition, phloem parenchyma cells contained chloroplasts with increased amounts of starch grains, sparse cytoplasm and reduced numbers of mitochondria. In the intermediary cells, the volume of cytoplasm was reduced by 50%, and the central vacuole was present. Moreover, the treatment at 9°C during the night led to RFO accumulation in the vascular bundles of the lateral branches and fruit carpopodiums. These ultrastructural changes of the transport structure (phloem) following the treatment at 9°C represented adaptive responses of melons to low temperature stresses. Future studies are required to examine whether these responses may affect phloem transport. [ABSTRACT FROM AUTHOR]

Monitoring air pollution at a city scale is essential for controlling urban air pollution in cities, especially megacities, in China. In this paper, data for 1 city center site and 5 paired (stands and non-forested) PM monitoring sites across urban-rural areas in Beijing were collected, and air PM and influential factors were analyzed. The results showed that the mean value of PM (February to December 2013) was lower in the stands (67.00 μg m) than in the non-forested sites (78.02 μg m). The diurnal variation was a bimodal double-dip type, and the average daily PM was lower in the vegetation areas than in the non-vegetation areas in both Changping Dingling (vegetation) and Changping town (non-vegetation) and showed day > night. In the typical pollution process, accompanied by an increase or decrease in PM and air quality index values, the higher the PM, the lower the wind speed. PM in the vegetation areas lagged behind PM in the non-vegetation areas on typical sunny days but not on typical rainy and windy days. On typical sunny days, the variation of PM in the vegetation areas was less than that in the non-vegetation areas. PM did not change significantly under rainy conditions and before a rain, but the variation was smaller after a rain under the typical rainfall process; under typical windy conditions, the variation was not significant. Therefore, in the typical pollution process and under typical weather conditions, the annual and diurnal variations of PM were smaller in the vegetation areas than in the non-vegetation areas. The above results confirm that the forest has a strong ability to purify air and absorb PM particulate matter and that the air quality in vegetation areas is better than the air quality in non-forested areas. [ABSTRACT FROM AUTHOR]

Flexible and high-performance electromagnetic absorbing materials of multi-walled carbon nanotube (MWCNT) buckypapers with Mn nanoparticles (NPSs) interlayer were fabricated via monodisperse solutions through layer by layer vacuum filtration method. The morphology and element composition of buckypapers were characterized by scanning electron microscopy, energy dispersive spectrometer, and X-ray diffraction. The formation of flexible MWCNT buckypapers with Mn NPS (0–30 wt. %) interlayer was attributed to nanostructure and morphology of the samples. When the blended Mn NPS content in buckypapers is 20 wt. %, there are evidently two larger absorption peaks (−13.2 dB at 3.41 GHz, −15.6 dB at 3.52 GHz) of the buckypaper with an absorbing thickness of 0.1 mm. The fundamental microwave absorption mechanism of the buckypapers is discussed. This work opens a new pathway towards tuning microwave absorbers performance and this method can be extended to exploit other excellent microwave absorbers with interlayer. [ABSTRACT FROM AUTHOR]

ABSTRACT A naval hybrid buckypaper was fabricated by vacuum filtration method with monodispersion solution of Fe3O4 decorated Multiwalled carbon nanotubes (MWCNTs). The morphology, element composition and phase structure of hybrid buckypaper were characterized by field-emission scanning electron microscope, energy dispersive spectrometer, and X-ray diffraction. The microwave absorption and complex electromagnetic properties of the composites surface coated MWCNTs buckypaper (or Fe3O4/MWCNTs hybrid buckypaper) have been investigated in the frequency range of 8-18 GHz. The results indicate that the microwave absorption properties of composite structure have been evidently improved due to the Fe3O4/MWCNTs hybrid buckypaper' high magnetic loss and suitable dielectric loss properties. The reflection loss of composite surface coated Fe3O4/MWCNTs hybrid buckypaper (with a matching thickness d = 0.1 mm) is below −10 dB in the frequency range of 13-18 GHz, and the minimum value is −15.3 dB at 15.7 GHz. Thus, Fe3O4/MWCNTs hybrid buckypaper can become a promising candidate for electromagnetic-wave-absorption materials with strong-absorption, thin-thickness and light-weight characteristics. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41974. [ABSTRACT FROM AUTHOR]

We analyzed fluctuation in Beijing's air quality over 328 days, based on air quality grades and air quality data from 35 atmospheric monitoring stations. Our results show the air over Beijing is subject to pollution 152 days of the year, or 46.34 %. Among all pollutants, fine particulates, solid or liquid, 2.5 μm or less in size (PM), appeared most frequently as the primary pollutant: 249 days, or 76 % of the sample year (328 days). Nitrogen dioxide (NO) and coarse particulates (PM) cause the least pollution, appearing only 7 and 3 days, or 2 and 1 % of the sample year, respectively. In Beijing, fine particulates like PM vary seasonally: 154.54 ± 18.60 in winter > 145.22 ± 18.61 in spring > 140.16 ± 20.76 in autumn > 122.37 ± 13.42 in summer. Air quality is best in August and worst in December, while various districts in Beijing experience different air quality. To be specific, from south to north and from west to east, air quality tends to improve. Meteorological elements have a constraining effect on air pollutants, which means there is a linear correlation between the air quality index and humidity, rainfall, wind speed, and temperature. Under a typical pollution scenario, the higher the air quality index (AQI) value, the lower the wind speed and the greater the relative humidity; the lower the AQI value, the higher the wind speed and lower the relative humidity. Analysis of influencing factors reveals that the air pollution is mainly particulate matter produced by burning coal, vehicle emissions, volatile oils and gas, fast development of food services, emissions from the surrounding region, and natural dust clouds formed in arid areas to the northwest. Topography affects the distribution of meteorological conditions, in turn varying air quality over the region from one location to another. Human activities also exercise impact on urban air quality with dual functions. [ABSTRACT FROM AUTHOR]

ABSTRACT The influence of the distribution type, Young's modulus, and volume fraction of the nanoparticles within the interphase region on the mechanical behavior of long fiber-reinforced composites with epoxy resin matrix under transverse tensile loading is investigated in this article. An infinite material containing unidirectional long fiber and periodic distribution of elastic, spherical nanoparticles was modeled using a unit cell approach. A stiffness degradation technique has been used to simulate the damage and crack progress of the matrix subjected to mechanical loading. A series of computational experiments performed to study the influence of the nanoparticle indicate that the mechanical properties, nanoparticle-fiber distance, and volume fraction of nanoparticle have a significant effect on both the stiffness and strength properties of these composite materials. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41573. [ABSTRACT FROM AUTHOR]

The accidental fall is the major risk for elderly especially under unsupervised states. It is necessary to real-time monitor fall postures for elderly. This paper proposes the fall posture identifying scheme with wearable sensors including MPU6050 and flexible graphene/rubber. MPU6050 is located at the waist to monitor the attitude of the body with triaxial accelerometer and gyroscope. The graphene/rubber sensors are located at the knees to monitor the moving actions of the legs. A real-time fall postures identifying algorithm is proposed by the integration of triaxial accelerometer, tilt angles, and the bending angles from the graphene/rubber sensors. A volunteer is engaged to emulate elderly physical behaviors in performing four activities of daily living and six fall postures. Four basic fall down postures can be identified with MPU6050. Integrated with graphene/rubber sensors, two more fall postures are correctly identified by the proposed scheme. Test results show that the accuracy for activities of daily living detection is 93.5% and that for fall posture identifying is 90%. After the fall postures are identified, the proposed system transmits the fall posture to the smart phone carried by the elderly via Bluetooth. Finally, the posture and location are transmitted to the specified mobile phone by short message. [ABSTRACT FROM AUTHOR]

Flexible strain sensors based on epoxy/graphene composite film with long molecular weight curing agents have critical roles in the development of advanced polymer composite films that combine mechanical robustness with functional properties such as electrical conductivity for many applications. In this experiment, flexible epoxy/GnP composite film is obtained by using flexible curing agent J2000. A percolation threshold of electrical conductivity was observed at merely 0.97 vol% GnPs, and the composite electrical conductivity increased to 10−6 S/cm at 5.0 vol %. The composite films were mechanically strong enough to be used as a flexible strain sensor. Our sensor can clearly detect the stretching of the forearm skin caused by a fist pulse and back of hand movement and achieve an enhancement of the resistance signal of up to 50%. When the GnPs content reaches 5%, Young's modulus and tensile strength increase to 21 MPa and 1.3 MPa, respectively. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47906. [ABSTRACT FROM AUTHOR]