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Background School closures and home confinement due to the ongoing COVID-19 pandemic may lead to disrupted sleep patterns. Consequently, it could increase the risk of children and adolescents’ mental health disorders. Methods In this prospective study, we randomly selected ten schools in Shanghai and conducted cluster sampling of students from each school. The first wave of the survey was conducted between January 3 and 21, 2020. Approximately two months after the COVID-19 outbreak declared, a second wave of the survey was conducted. In total, 2427 individuals were surveyed in both waves using the same sampling method. Participants’ mental health status (depression, anxiety and stress), sleep patterns and other demographic information were measured in both waves. Multivariate regression analysis was used to examine the associations between sleep patterns and mental health status. Results During the COVID-19 pandemic, a total of 873 participants (19.9%), 1100 participants (25.1%), and 670 participants (15.3%) reported depression, anxiety, and stress symptoms, respectively. Significant changes of both sleep duration and sleep-wake cycle patterns were observed before and during the COVID-19 pandemic. Moreover, shorter sleep duration and late to rise patterns (including early to bed late to rise and late to bed late to rise) were found to be associated with higher odds of having mental illnesses during the pandemic. Conclusion These results suggest there is a pressing need to monitor children's and adolescents’ health behavior and mental health and develop timely evidence‐based strategies and interventions to mitigate adverse behavioral and psychological impacts caused by these unprecedented challenges.

Traditional aerial vehicles have limitations in their capabilities due to actuator constraints, such as motor saturation. The hardware components and their arrangement are designed to satisfy specific requirements and are difficult to modify during operation. To address this problem, we introduce a versatile modular multi-rotor vehicle that can change its capabilities by reconfiguration. Our modular robot consists of homogeneous cuboid modules, propelled by quadrotors with tilted rotors. Depending on the number of modules and their configuration, the robot can expand its actuation capabilities. In this paper, we build a mathematical model for the actuation capability of a modular multi-rotor vehicle and develop methods to determine if a vehicle is capable of satisfying a task requirement. Based on this result, we find the optimal configurations for a given task. Our approach is validated in realistic 3D simulations, showing that our modular system can adapt to tasks with varying requirements.

Dexterous manipulation of objects through fine control of physical contacts is essential for many important tasks of daily living. A fundamental ability underlying fine contact control is compliant control, \textit{i.e.}, controlling the contact forces while moving. For robots, the most widely explored approaches heavily depend on models of manipulated objects and expensive sensors to gather contact location and force information needed for real-time control. The models are difficult to obtain, and the sensors are costly, hindering personal robots' adoption in our homes and businesses. This study performs model-free reinforcement learning of a normal contact force controller on a robotic manipulation system built with a low-cost, information-poor tactile sensor. Despite the limited sensing capability, our force controller can be combined with a motion controller to enable fine contact interactions during object manipulation. Promising results are demonstrated in non-prehensile, dexterous manipulation experiments.

Additional file 1. hPAEPIC activity at different concentrations of LPS was detected by cell counting kit 8 (CCK-8) assay.

Lack of texture often causes ambiguity in matching, and handling this issue is an important challenge in optical flow estimation. Some methods insert stacked transformer modules that allow the network to use global information of cost volume for estimation. But the global information aggregation often incurs serious memory and time costs during training and inference, which hinders model deployment. We draw inspiration from the traditional local region constraint and design the local similarity aggregation (LSA) and the shifted local similarity aggregation (SLSA). The aggregation for cost volume is implemented with lightweight modules that act on the feature maps. Experiments on the final pass of Sintel show the lower cost required for our approach while maintaining competitive performance.

This is the supplement file of "Exacerbated ozone pollution in the greening northern China".

Background: Tranexamic acid (TXA) has been widely applied to reduce perioperative bleeding. Recently, several studies focused on the administration of TXA in the treatment for with intertrochanteric fracture patients treated with intramedullary fixation. However, the efficacy and safety of TXA in these studies remain controversial. Therefore, we performed this systematic review and meta-analysis to investigate the efficacy and safety of TXA in intertrochanteric fracture patients treated with intramedullary fixation.Methods: We systematically searched electronic databases, including Cochrane, PubMed, and EMBASE, up to 16 May 2022. The efficacy and safety of TXA was evaluated in four aspects, which were bleeding-related outcomes, non-bleeding-related outcomes, thromboembolic events, and other complications. The outcomes of these studies were extracted and analyzed by RevMan Manager 5.4.Results: Finally, nine randomized controlled trials, involving nine hundred and seventy-two intertrochanteric fracture patients treated with TXA, were enrolled in this study. In the bleeding-related outcomes, TXA group was significantly lower than the control group in terms of total blood loss (MD = −219.42; 95% CI, −299.80 to −139.03; p < 0.001), intraoperative blood loss (MD = −36.81; 95% CI, −54.21 to −19.41; p < 0.001), hidden blood loss (MD = −189.23; 95% CI, −274.92 to −103.54; p < 0.001), and transfusion rate (RR = 0.64; 95% CI, 0.49 to 0.85; p = 0.002). Moreover, the postoperative hemoglobin on day 3 of the TXA group was significantly higher than that of the control group (MD = 5.75; 95% CI, 1.26 to 10.23; p = 0.01). In the non-bleeding-related outcomes, the length of hospital stays was significantly shorter in the TXA group (MD = −0.67; 95% CI, −1.12 to −0.23; p = 0.003). In terms of thromboembolic events, there was no significant differences between the TXA group and control group in deep vein thrombosis, pulmonary embolism, myocardial infarction, and ischemic stroke. As for complications and mortality, there was no significant differences between the TXA group and control group in respiratory infection, renal failure, and postoperative mortality within 1 year.Conclusion: TXA is an effective and safe drug for perioperative bleeding control in intertrochanteric fracture patients treated with intramedullary fixation. However, the long-term efficacy of TXA still needs to be investigated by large-scale multicenter randomized controlled trials.Level of evidence: II, Systematic review and Meta-analysis.Systematic Review Registration:https://inplasy.com/, identifier [INPLASY202280027]

Objective: To analyze the effect of multidisciplinary cooperation mode (MCM) led by infusion nurse specialists (INSs) on peripherally inserted central catheters (PICC) catheterization and indwelling nursing quality. Methods: Participants’ demographic information, catheter types, catheterization approaches, puncture site, tip position, professional title of nurses, success rate of catheterization, consultation rate, detection rate of complications and outcome improvement rate of 6576 outpatients and hospitalized patients with PICC were analyzed retrospectively by a software named “questionnaire stars,” in a large tertiary general hospital in Shanghai, from January 2015 to December 2019. SPSS 26.0 for Windows was used for data collection and description, Chi-square test were used for statistical analysis of enumeration data, and p Results: According to the catheter types’ data, the use rate of three-way valve catheters decreased from 79.9% to 14.5%, while the use rate of three-way valve solo catheters increased from 12.7% to 51.6%, and the use rate of power injectable and open-ended catheters increased from 7.4% to 33.9%. According to the data of PICC catheterization method, conventional technology decreased significantly from 16.8% to 1.1%, modified Seldinger technique (MST) increased gradually from 26.1% to 51.3%, while ultrasound guided modified Seldinger technique (US and MST) decreased slightly from 57.2% to 47.6%. 7.5% catheter tip ends were malpositioned while nine indwelled PICCs were traced to have tip end malposition. The consultation rate was significantly higher than that before applying MCM led by INSs ( x2 = 151.713, p 2 = 5.499, p 2 = 187.589, p Conclusion: After the application of INSs-led MCM, progresses have been achieved. The nursing quality of patients’ PICC was significantly improved than before.

The design of preform plays a key role in the precision forming of complex-shaped components with thin walls and large areas of webs. In the present work, two typical kinds of box-shaped forgings of 5A06 aluminum-alloy were selected as research objects, including the symmetric rectangular base forging and the asymmetric arc cover forging. The preform design method was proposed during isothermal back extrusion of boxlike forging, in which metal flow law of billets with equal thickness revealed by finite element (FE) simulation was quite useful for the billet design. The simulation results successfully predicted folding defects at the bottom of the base forging and inadequate filling at lateral walls of the cover forging, which were caused by inappropriate billet geometry and loading mode. According to the simulation and experimental results, the reverse loading of the rectangular base billet with variable thickness avoided the appearance of the folding at the bottom. The base forging without defects was formed successfully under reverse loading by using the billet with four 60 mm × 90 mm × 5 mm bosses and 15° transition surfaces, while the cover forging without defects was formed successfully by using the billet with 15° transition surfaces and two bosses whose heights were both 48 mm. Both the two boxlike forgings formed with modified billets exhibited perfect distribution of flow lines. Meanwhile, the lateral walls and webs possessed higher tensile strength, higher elongation, finer and more elongated grains than raw material. Therefore, the thermal backward extrusion was an effective process to precisely form complexly boxlike rib/web workpiece.

We present a design, model, and control for a novel jumping-flying robot that is called PogoDrone. The robot is composed of a quadrotor with a passive mechanism for jumping. The robot can continuously jump in place or fly like a normal quadrotor. Jumping in place allows the robot to quickly move and operate very close to the ground. For instance, in agricultural applications, the jumping mechanism allows the robot to take samples of soil. We propose a hybrid controller that switches from attitude to position control to allow the robot to fall horizontally and recover to the original position. We compare the jumping mode with the hovering mode to analyze the energy consumption. In simulations, we evaluate the effect of different factors on energy consumption. In real experiments, we show that our robot can repeatedly impact the ground, jump, and fly in a physical environment.

Light-driven actuators that directly convert light into mechanical work have attracted significant attention due to their wireless advantage and ability to be easily controlled. However, a fundamental impediment to their application is that the continuous motion of light-driven flexible actuators usually requires a periodically switching light source or the coordination of other additional hardware. Here, for the first time, continuous flapping-wing motion under sunlight is realized through the utilization of a simple nanocrystalline metal polymer bilayer structure without the coordination of additional hardware. The light-driven performance can be controlled by adjusting the grain size of the upper nanocrystalline metallic layer or selecting metals with different thermodynamic parameters. The achieved highest frequency of flapping-wing motion is 4.49 Hz, which exceeds the frequency of real butterfly wings, thus informing the further development of sunlight-driven bionic flying animal robotics without external energy consumption. The flapping-wing motion has been used to realize a light-driven whirligig, a light-driven sailboat, and photoelectric energy harvesting. Furthermore, the flexible bilayer actuator features the ability to be driven by light and electricity, low-power actuation, a large deflection, fast actuation speed, long-time stability, strong design ability, and large-area facile fabrication. The bilayer film considered herein represents a simple, general, and effective strategy for preparing photoelectric-driven flexible actuators with target performances and informs the standardization and industrial application of flexible actuators in the future.

Additional file 1: Table S1. Informative SNPs flanking STK11gene of Peutz���Jeghers syndrome in case1

In this letter, we investigate Rate-Splitting Multiple Access (RSMA) for an uplink communication system with finite blocklength. Considering a two-user Single-Input Single-Output (SISO) Multiple Access Channel (MAC), we study the impact of Signal-to-Noise Ratio (SNR), blocklength, power allocation and target rate on the error probability performance of RSMA where one user message is split. We demonstrate that RSMA can improve the error probability performance significantly compared to Non-Orthogonal Multiple Access (NOMA) and RSMA can have a larger rate region than NOMA., Comment: 5 pages, 4 figures

The early stages of mammalian embryonic development involve the participation and cooperation of numerous complex processes, including nutritional, genetic, and epigenetic mechanisms. However, in embryos cultured in vitro, a developmental block occurs that affects embryo development and the efficiency of culture. Although the block period is reported to involve the transcriptional repression of maternal genes and transcriptional activation of zygotic genes, how epigenetic factors regulate developmental block is still unclear. In this study, we systematically analyzed whole-genome methylation levels during five stages of sheep oocyte and preimplantation embryo development using single-cell level whole genome bisulphite sequencing (SC-WGBS) technology. Then, we examined several million CpG sites in individual cells at each evaluated developmental stage to identify the methylation changes that take place during the development of sheep preimplantation embryos. Our results showed that two strong waves of methylation changes occurred, namely, demethylation at the 8-cell to 16-cell stage and methylation at the 16-cell to 32-cell stage. Analysis of DNA methylation patterns in different functional regions revealed a stable hypermethylation status in 3′UTRs and gene bodies; however, significant differences were observed in intergenic and promoter regions at different developmental stages. Changes in methylation at different stages of preimplantation embryo development were also compared to investigate the molecular mechanisms involved in sheep embryo development at the methylation level. In conclusion, we report a detailed analysis of the DNA methylation dynamics during the development of sheep preimplantation embryos. Our results provide an explanation for the complex regulatory mechanisms underlying the embryo developmental block based on changes in DNA methylation levels.

As one of the most sensitive regions to global climate change, alpine tundra in many places around the world has been undergoing dramatic changes in vegetation communities over the past few decades. Herbaceous plant species in the Changbai Mountains area have significantly expanded into tundra shrub communities over the past 30 yr. Soil microbial communities, enzyme activities, and soil nutrients are intertwined with this expansion process. In order to understand the responses of the soil microbial communities to such an expansion, we analyzed soil microbial community structures and enzyme activities in shrub tundra as well as areas with three different levels of herbaceous plant expansion. Our investigation was based on phospholipid fatty acid (PLFA) analysis and 96-well microtiter plates. The results showed that herbs have expanded greatly in the tundra, and they have become the dominant species in herbaceous plant expansion areas. There were differences for community composition and appearance among the shrub tundra and the mild expansion, moderate expansion, and severe expansion areas. Except for soil organic matter, soil nutrients were increased in herbaceous plant expansion areas, and the total nitrogen (TN), total phosphorus (TP), available nitrogen (AN), and available phosphorus (AP) were greatest in moderate expansion areas (MOE), while soil organic matter levels were highest in the non-expanded areas (CK). The total soil PLFAs in the three levels of herbaceous plant expansion areas were significantly higher than those in the non-expanded areas, and total soil PLFAs were highest in the moderately expanded area and lowest in the severely expanded area (SEE). Bacteria increased significantly more than fungi and actinomycetes with herbaceous plant expansion. Soil hydrolase activities (β-1,4-glucosidase (βG) activity, β-1, 4-N-acetylglucosaminidase (NAG) activity, and acid phosphatase (aP) activity) were highest in MOE and lowest in the CK treatment. Soil oxidase activities (polyphenol oxidase (PPO) activities and peroxidase (PER) activities) were also highest in MOE, but they were lowest in the SEE treatment. The variations in total soil PLFAs with herbaceous plant expansion were mostly correlated with soil organic matter and available phosphorus concentrations, while soil enzyme activities were mostly correlated with the total soil nitrogen concentration. Our results suggest that herbaceous plant expansion increase the total soil PLFAs and soil enzyme activities and improved soil nutrients. However, soil microorganisms, enzyme activity, and nutrients responded differently to levels of herbaceous plant expansion. The soil conditions in mild and moderate expansion areas are more favorable than those in severe expansion areas.

The complicated nature of current wet crude oil requires a further upgrade of electrical dehydration technology that can satisfy the latest processing criteria. This study investigated the dehydration efficiency of a dispersed phase of distilled water in a continuous phase of conduction oil in electric fields created by three proposed electrodes. The electric field distribution was created and analyzed using COMSOL Multiphysics software and the level-set method. The results show that the electric fields created by our proposed electrodes can aid the dehydration process by optimizing the electric field distribution and the electropolymerization behaviors. Furthermore, the results indicate that the non-uniform fields formed by the proposed electrodes can lead to acceleration in the movement of water droplets as well as a facilitated sedimentation stage. A water film created by a copper mesh electrode can induce a droplet–interface coalescence, and the geometry of a grid electrode can promote a two-phase oil and water movement. These results could provide insights for the future design of the best electrode geometry for efficient electrocoalescence.

COVID-19 has generated an unprecedented impact on Chinese tourism since the beginning of 2020. The Chinese industry has used pauses in the offline sector and an advanced domestic online business infrastructure to follow times' paces. Tourist companies have greatly enlarged the online department's size and started to pursue the innovation of quality and intelligence. The key question underpinning the content is the pattern and style of tourism in China will be like with the guidance of Rural Revitalization Policy and'14th five-year cultural tourism plans.

Recently, the term "fake news" has been broadly and extensively utilized for disinformation, misinformation, hoaxes, propaganda, satire, rumors, click-bait, and junk news. It has become a serious problem around the world. We present a new system, FaNDS, that detects fake news efficiently. The system is based on several concepts used in some previous works but in a different context. There are two main concepts: an Inconsistency Graph and Energy Flow. The Inconsistency Graph contains news items as nodes and inconsistent opinions between them for edges. Energy Flow assigns each node an initial energy and then some energy is propagated along the edges until the energy distribution on all nodes converges. To illustrate FaNDS we use the original data from the Fake News Challenge (FNC-1). First, the data has to be reconstructed in order to generate the Inconsistency Graph. The graph contains various subgraphs with well-defined shapes that represent different types of connections between the news items. Then the Energy Flow method is applied. The nodes with high energy are the candidates for being fake news. In our experiments, all these were indeed fake news as we checked each using several reliable web sites. We compared FaNDS to several other fake news detection methods and found it to be more sensitive in discovering fake news items.

Competitive Self-Play (CSP) based Multi-Agent Reinforcement Learning (MARL) has shown phenomenal breakthroughs recently. Strong AIs are achieved for several benchmarks, including Dota 2, Glory of Kings, Quake III, StarCraft II, to name a few. Despite the success, the MARL training is extremely data thirsty, requiring typically billions of (if not trillions of) frames be seen from the environment during training in order for learning a high performance agent. This poses non-trivial difficulties for researchers or engineers and prevents the application of MARL to a broader range of real-world problems. To address this issue, in this manuscript we describe a framework, referred to as TLeague, that aims at large-scale training and implements several main-stream CSP-MARL algorithms. The training can be deployed in either a single machine or a cluster of hybrid machines (CPUs and GPUs), where the standard Kubernetes is supported in a cloud native manner. TLeague achieves a high throughput and a reasonable scale-up when performing distributed training. Thanks to the modular design, it is also easy to extend for solving other multi-agent problems or implementing and verifying MARL algorithms. We present experiments over StarCraft II, ViZDoom and Pommerman to show the efficiency and effectiveness of TLeague. The code is open-sourced and available at https://github.com/tencent-ailab/tleague_projpage, Comment: 21 pages, 3 figures, technical report

Vegetation is the main component of the terrestrial ecosystem and plays a key role in global climate change. Remotely sensed vegetation indices are widely used to detect vegetation trends at large scales. To understand the trends of vegetation cover, this research examined the spatial-temporal trends of global vegetation by employing the normalized difference vegetation index (NDVI) from the Advanced Very High Resolution Radiometer (AVHRR) Global Inventory Modeling and Mapping Studies (GIMMS) time series (1982–2015). Ten samples were selected to test the temporal trend of NDVI, and the results show that in arid and semi-arid regions, NDVI showed a deceasing trend, while it showed a growing trend in other regions. Mann-Kendal (MK) trend test results indicate that 83.37% of NDVI pixels exhibited positive trends and that only 16.63% showed negative trends (P < 0.05) during the period from 1982 to 2015. The increasing NDVI trends primarily occurred in tree-covered regions because of forest growth and re-growth and also because of vegetation succession after a forest disturbance. The increasing trend of the NDVI in cropland regions was primarily because of the increasing cropland area and the improvement in planting techniques. This research describes the spatial vegetation trends at a global scale over the past 30+ years, especially for different land cover types.

This project aimed to design a new type of vibration isolation mechanism with quasi-zero-stiffness (QZS) and analyze the QZS systems’ characteristics by computation and numerical simulation. First, the force–displacement and stiffness–displacement relational expressions of the QZS systems were established based on the study of system force and stiffness characteristics. Second, the nonlinear dynamic equations of the system under the excitation of harmonic force and harmonic displacement were established, and the effect of damping ratio, excitation amplitude, and nonlinear term under the transmissibility mechanism system was analyzed by the average method. Finally, the response time and stability of the QZS vibration isolator were analyzed under different circumstances through numerical simulation. The excitation amplitude, damping ratio, and nonlinear term have a great influence on the transmissibility of the system. In addition, under three different working conditions, the mechanism can have good vibration isolation characteristics and can meet the requirement of low-frequency vibration isolation. A novel type of the QZS systems has been investigated, and it is found that the influence of the excitation amplitude and the nonlinear term are just the same on the system transmissibility through the statics and dynamics calculations. Meanwhile, when damping ratio was increased, the transmissibility of the QZS systems could be reduced. The numerical simulations show that the system has faster response and smaller amplitude for sine wave, single shock, and multi-frequency excitations, which is more suitable for low-frequency vibration isolation.

Vegetation in high altitude areas normally exhibits the strongest response to global warming. We investigated the tundra vegetation on the Changbai Mountains and revealed the similarities and differences between the north and the southwest slopes of the Changbai Mountains in response to global warming. Our results were as follows: 1) The average temperatures in the growing season have increased from 1981 to 2015, the climate tendency rate was 0.38°C/10yr, and there was no obvious change in precipitation observed. 2) The tundra vegetation of the Changbai Mountains has changed significantly over the last 30 years. Specifically, herbaceous plants have invaded into the tundra zone, and the proportion of herbaceous plants was larger than that of shrubs. Shrub tundra was transforming into shrub-grass tundra. 3) The tundra vegetation in the north and southwest slopes of the Changbai Mountains responded differently to global warming. The southwest slope showed a significantly higher degree of invasion from herbaceous plants and exhibited greater vegetation change than the north slope. 4) The species diversity of plant communities on the tundra zone of the north slope changed unimodally with altitude, while that on the tundra zone of the southwest slope decreased monotonously with altitude. Differences in the degree of invasion from herbaceous plants resulted in differences in species diversity patterns between the north and southwest slopes. Differences in local microclimate, plant community successional stage and soil fertility resulted in differential responses of tundra vegetation to global warming.

To realize the efficient current-induced spin-orbit torque (SOT) magnetization switching, the understanding of spin source with unique physics for the charge-to-spin conversion is very important. Here, we demonstrate the current-induced SOT magnetization switching by considering non-collinear spin moments mixed by Rashba-like Sy, Dresselhaus-like Sx, and out-of-plane like Sz by using micromagnetic simulation. The magnetization switching with considering three configurations of out-of-plane magnetization (along the z-direction), in-plane magnetization along the x and y-direction have been studied. The current induced out-of-plane spin moment can effectively contribute unconventional out-of-plane damping like torque to switch the mz at zero magnetic field. Similarly, the current induced Dresselhaus-like spin moments can switch mx effectively. Our results may provide a new degree of freedom for the understanding of current-induced SOT magnetization switching by non-collinear spin source for the potential application of spintronics devices.

Actuating materials can convert external stimuli (humidity, light, electricity, etc.) into mechanical energy and realize multiple forms of movements. However, a majority of current actuating materials are driven by a single stimulus with a small degree of actuation and rough control which is unfavorable for practical applications. Here, a new type of bidirectional actuating material based on carbon nanotube/PDMS composites and chitosan films is proposed. Thanks to the robust mechanical support by PDMS, due to the ultra-large water capacity in between chitosan chains and strong near-infrared light absorption by carbon nanotube layers, the actuator can be driven by humidity and light for an ultra-large actuation curvature (3.91 cm-1 in humidity actuation, 3.84 cm-1 in light actuation). The well-established light power-curvature, relative humidity-curvature profiles and a fine mechanic modelling of the actuator show the possibility of controlling the actuator's bending. A lab application as a cargo-moving device preliminarily demonstrates a robust mechanical functionality of this actuator with a low body weight.

This paper performs a optimization research for delta shape rotor topology in interior permanent magnet synchronous motor (IPMSM). The permanent magnet (PM)arrangement, pole-arc coefficient and the angle between two main PMs are mains influence factors of IPMSM performance. This paper based on a delta shape 72s12p IMPSM model and applied Taguchi method to optimized the efficiency, average operating torque (AOT)and torque ripple proportion. Finite element method and performance simulation were carried out by using ANSOFT. A prototype was fabricated and verfied experiment was carried out. The results show that by using the Taguchi method the performance have been effectively improved.

Along with the development of Permanent Magnet Synchronous Machine (PMSM), the variation of rotor temperature has become the main restriction of Electrical Vehicle (EV) motor design. In this paper, we mainly investigated the relationship between temperature and performance of the motor (output torque, efficiency map, etc.). Simulating results and analysis are given based on the CAE software ANSOFT, using a specific PMSM model equipped with Permanent Magnet (PM) with the grade N38UH. Several conclusions are given to provide a new perspective in motor R&D process, by adding the consideration of relationship between temperature and performance while remaining undemagnetized in normal working condition.

The synapses are essential to the brain neuromorphic system, and especially the plasticity of synapse contributes significantly in cognitive functions. Ferroelectric tunnel junction (FTJ) can be utilized to emulate the synaptic functions by the effective control of resistance state, which is related with the ferroelectric polarization state of barrier layer. Here, we study the emulation of a synaptic response in the fabricated organic ferroelectric tunnel junctions (OFTJs) with Polyvinylidene fluoride (PVDF) polymer barriers. The functions of long-term potentiation and long-term depression are demonstrated by exploring the relationship between resistance and polarizing pulse. In addition, our device can be also utilized to realize multi-memory function, a device with six-resistance states is demonstrated. Our results may provide a new degree of freedom for the realization of synaptic functions in OFTJs.

Light environment significantly impacts the effectiveness of fish population restoration in developed watersheds, subserving fish passage reconstruction in hydraulic complex and habitat rehabilitation. To develop an interior connection between light-related fish response from the laboratory and field fish conservation practice, we employed a new indexing system, consisting of phototaxis rate, relative swimming speed (RSS), and optic evasion coefficient (OEC), to quantify the light-induced behaviors in Ptychobarbus kaznakovi, a representative rare cyprinid in Tibet, China, at four experimental illuminance levels (15 lx, 30 lx, 60 lx, 120 lx) and four wavelengths (red, yellow, green, blue). The fish showed negative phototaxis at all given illuminances and wavelengths. Under red light, the OEC increased significantly from 0.642 at 15 lx to 0.782 at 30 lx (P = 0.029), while the RSS decreased significantly from 3.752 to 2.383 (P

The melt flow stability has a direct effect on crystal quality during the horizontal ribbon growth (HRG) process. The mixed convection in the HRG system includes thermocapillary convection, buoyancy convection, and the convection induced by the lid-driven boundary. In this study, the influences of relevant parameters such as Marangoni number, Rayleigh number, Biot number, and horizontal motion of the ribbon on flow and temperature fields have been analyzed using computational fluid dynamics. A thermal-fluid numerical model was developed by solving the Navier–Stokes and energy equations to obtain the flow, pressure, and temperature fields. The horizontal motion of the ribbon was assumed the lid-driven boundary. The results showed that the magnitude of the Marangoni number played a decisive role in the flow and temperature distribution inside the melt. In the case of a small Marangoni number, the increase in horizontal motion velocity of the ribbon was the main factor to induce convection in the melt, and the internal temperature distribution was carried out in a heat conduction mode. With the increasing Marangoni number, the thermocapillary convection was enhanced, and the convection induced by the ribbon motion was overwhelmed by the thermocapillary effect. Moreover, the increase in Biot number could reduce the temperature nonlinearity of the free surface. Particularly, the free surface temperature begins to oscillate as the Marangoni number is increased above a threshold. A larger Marangoni number could easily result in a temperature oscillation with a larger amplitude. The results indicated that the thermocapillary effect was more sensitive to temperature and flow oscillations, and should receive more attention.

This paper proposes a new QZS joint actuator, which uses a torsion electromagnetic spring (TES) that can generate negative stiffness in parallel with a flexible rod with positive stiffness to obtain QZS characteristics with high static and low motion. In this paper, the expression of TES magnetic moment and stiffness is obtained by static analysis, the simulation is carried out by ANSYS Maxwell finite element software and the effect of TES structure parameters and current on its negative stiffness characteristics is analyzed. Then the dynamic model of QZS joint actuator is established, and the amplitude-frequency response function and torque transmissibility analytical expression are obtained by harmonic balance method, the good vibration isolation performance of QZS joint actuator is revealed. Finally, the stiffness and vibration isolation performance experiments are carried out with the QZS joint actuator to verify the correctness of the theoretical analysis, which indicates that it has a wide range of application background and research significance.

Electrocoalescence is an energy-efficient and environmentally-friendly process for breaking water-in-oil emulsions. It has been used extensively in the oil and petroleum industries. In this study, the electrocoalescence process of nanoparticle/surfactant-stabilized water droplets with a planar interface in the presence of non-uniform electric fields was experimentally investigated. The effects of electric field patterns (i.e. uniform and non-uniform fields) and nanoparticles (i.e. concentrations) on the drop-interface electrocoalescence process were systematically examined, analyzed, and discussed. The results showed that the presence of Sodium Dodecyl Sulfate (SDS) significantly increased the volume of secondary droplets and led to the apex disintegration of the main secondary droplet because of the low surface tension. At high SiO2 concentrations, the liquid bridge between the droplet and interface was difficult to form, and the whipping filament regime, sheet breakup regime, and varicose jet breakup regime, were observed, which were determined by the accumulating surface charge. In addition, three types of non-uniform fields induced by different geometrical electrode configurations, i.e. grid electrodes, mesh electrodes, and coupled electrodes, were proposed and the electric field distributions were calculated in COMSOL Multiphysics. With increasing SiO2 concentrations, coupled electrodes produced much smaller detached droplet volumes than those of pairwise mesh and grid electrodes, which was helpful to complete the coalescence of the drop and interface. Furthermore, flat electrodes, which induced a uniform electric field, produced much larger secondary droplet volumes than those of the electrodes generating non-uniform electric fields. In summary, the utilization of coupled electrodes had a positive effect on drop-interface coalescence and increased the overall separation efficiency. The outcome of this work is potentially useful in the design of compact and efficient oil-water electro-dehydration devices.

This paper proposes a semi-active variable stiffness vibration isolation system based on electromagnetic spring for the low-frequency vibration isolation of mass-varying objects. It is achieved by four straight leaf springs in parallel to an electromagnetic spring system composed of a single electromagnet and a permanent magnet. The equivalent magnetic circuit method is used to compute electromagnetic force of the electromagnetic spring system, and mathematical model of the semi-active vibration isolation system is established according to Maxwell's equations. The nonlinear mathematical model is linearized at the equilibrium point by using the Taylor series expansion theorem to establish linear state-space representation of the system, and then using the traditional PID control method, a double closed-loop feedback control system of the inner current loop and outer location loop is designed. By controlling the current in the coil, the equivalent stiffness and electromagnetic force of the system are variable to achieve semi-active control. Furthermore, the control block diagram of the semi-active vibration isolation system is built based on Simulink software, then make a simulation analysis to the vibration isolation performance of the system and compare the effects of vibration isolation with inner current loop control and without inner current loop control, respectively. Finally, the experiments prove the correctness of the theory. It concludes that this semi-active vibration isolation system is a vibration isolation system with broad application prospects, which has fast current response, high vibration isolation efficiency, and an excellent vibration isolation effect for the low-frequency disturbance of mass-varying objects.

In recent years, herbaceous species such as Deyeuxia angustifolia (Kom.) Y. L. Chang has invaded alpine tundra regions of the western slope of the Changbai Mountains. Because atmospheric nitrogen deposition is predicted to increase under a warming climate and D. angustifolia is sensitive to nitrogen addition, field experiments were conducted from 2010 to 2013 to determine the effect of increased nitrogen deposition on the mechanisms of D. angustifolia invasion. The goal of this study is to evaluate the impact of increased nitrogen deposition on the changes in alpine tundra vegetation (consisting mostly of Rhododendron chrysanthum Pall. and Vaccinium uliginosum Linn.). The results showed that: 1) simulated nitrogen deposition affected overall characteristics and structure of R. chrysanthum and V. uliginosum communities and had a positive impact on the growth of tundra vegetation invaded by D. angustifolia; 2) R. chrysanthum was more resistant to invasion by D. angustifolia than V. uliginosum; 3) simulated nitrogen deposition could improve the growth and enhance the competitiveness of D. angustifolia, which was gradually replacing R. chrysanthum and V. uliginosum and might become the dominant species in the system in future, transforming alpine tundra into alpine meadow in the Changbai Mountains.

© 2017 American Chemical Society. Chiral metal-organic frameworks have attracted interest for enantioselective separations and catalysis because of their high crystallinity and pores with tunable shapes, sizes, and chemical environments. Chiral frameworks of the type M2(dobpdc) (M = Mg, Mn, Fe, Co, Ni, Zn; dobpdc4- = 4,4′-dioxidobiphenyl-3,3′-dicarboxylate) seem particularly promising for potential applications because of their excellent stability, high internal surface areas, and strongly polarizing open metal coordination sites within the channels, but to date these materials have been isolated only in racemic form. Here, we demonstrate that when appended with the chiral diamine trans-1,2-diaminocyclohexane (dach), Mg2(dobpdc) adsorbs carbon dioxide cooperatively to form ammonium carbamate chains, and the thermodynamics of CO2 capture are strongly influenced by enantioselective interactions within the chiral pores of the framework. We further show that it is possible to access both enantiomers of Mg2(dobpdc) with high enantiopurity (≥90%) via framework synthesis in the presence of varying quantities of d-panthenol, an inexpensive chiral induction agent. Investigation of dach-M2(dobpdc) samples following CO2 adsorption - using single-crystal and powder X-ray diffraction, solid-state nuclear magnetic resonance spectroscopy, and density functional theory calculations - revealed that the ammonium carbamate chains interact extensively with each other and with the chiral M2(dobpdc) pore walls. Subtle differences in the non-covalent interactions accessible in each diastereomeric phase dramatically impact the thermodynamics of CO2 adsorption.

Grassland fire is a major disturbance to ecosystems and economies throughout the world.Research on the spatial pattern of grassland fire is therefore important in understanding the dynamics of fire disturbance and providing evidence for fire management and prevention.In this study we used a spatial point process modeling approach to study the factors contributing to fire occurrence in the Hulunbeir grassland of the Inner Mongolia Autonomous Region.In previous studies,Ripley′ K function,Kernel density and Poisson model have been used in the studies of spatial-temporal pattern of forest fires.But the distribution pattern of grassland fires was usually described by overlaying fire points on top of the administrative districts or study regions.The properties of spatial distribution,such as clustering,dispersion,randomness,were often omitted.In this study,Repley′s K function was used to investigate the spatial distribution pattern of human-caused fires in the Hulunbeir grassland.The distribution of fire locations was found to be spatially clustered in the months of fire season and between years.The distances of spatial cluster distribution were less than 250km,265km,245km,200km and 245km in April,May,June,September and October respectively.The statistical test showed that the cluster distributions were significant except for October.The distances of spatial cluster distribution were less than 210km,280km,260km,220km and 220km in 1976—1980,1981—1984,1985—1988,1989—192 and 1993—1996 respectively.All the cluster distributions were significant.The spatial distribution densities of human-caused grassland fires and the impacting factors including residential locations,roads and fields were calculated by the function of Kernel density.The results showed that human-caused grassland fires were widely distributed and the main "hot-spot" was in the extent of 123.05—124.82°E,48.25—50.21°N.The second "hot-spot" had four regions and the center locations were: 117.52°E,49.51°N;120.73°E,49.24°N;121.94°E,48.74°N;123.73°E,50.58°N.The "hot-spots" of residential points and fields were distributed in the east and middle of the study area.The "hot-spot" of roads was more widespread than the residential points and fields.The spatial distribution density of human-caused grassland fires was significantly correlated with the impacting factors(residential points,roads,fields,weather and topography) and the Pearson coefficients were 0.448,0.236,0.602,0.161 and-0.042 respectively(P0.001).The spatial patterns of fire sources(residential points,roads and fields) are found to be more closely associated with the spatial density of human-caused grassland fires.The correlation of weather with the spatial pattern of grassland fire was at a lower degree than these of residential points,roads and fields.It showed that the weather condition was not a limiting factor in affecting the occurrence of human-caused grassland fire in the fire season.Overall,the most important factors impacted human-caused grassland fire occurrence were the spatial distribution of fire sources(residential points,roads and fields).Topography has negative correlation with grassland fire occurrence.The reason may be that the human activities decreased with the increase of slope.In each month of fire seasons,the spatial distribution pattern of human-caused grassland fires was also mainly impacted by the distribution of fire source(residential points,roads and fields).The methods developed in this study can be applied to predict human-caused grassland fire risk,aiding decisions in preventative management strategies of grassland fires.

A two-layer stripline configuration for cascaded trisection (CT) bandpass filter is proposed to realize wider fractional bandwidth and higher center frequency. In this configuration, resonators are located alternatively on two different planes to allow strong overlapped coupling between adjacent resonators, and stripline structure enables resonators with higher resonant frequency to be used in the construction of CT bandpass filters. To prove the feasibility of this configuration, a five-pole CT bandpass filter with 10-GHz center frequency and 13% fractional bandwidth is designed with this method and simulated on Ansys HFSS 15.0. The simulation results illustrate that this configuration can realize wider fractional bandwidth as well as higher center frequency compared with traditional planar microstrip configurations.

The Penglai Group in the Jiaobei Belt is the only remaining cover of the Archaean to Early Proterozoic crystalline basement in eastern Shandong. The ages of deposition of the Penglai Group and of its deformation and metamorphism have long been a subject of speculation. Whole-rock Rb-Sr ages, illite-whole-rock pair Rb-Sr ages and illite K - Ar ages recently obtained from the Penglai Group slates are reported and interpreted in this paper. On the basis of structural and metamorphic studies coupled with analyses of illite crystallinity, XRD and SEM, a whole-rock age of 473 ± 32 Ma (Ordovician) is interpreted as the time of termination of burial metamorphism experienced by the Penglai Group. Therefore, the age of the Penghai Group is older than Ordovician. The first-phase folding and syntectonic low greenschist facies metamorphism in the Penglai Group, i.e. the Penglai Movement, took place before 299±4 Ma B.P., i.e in the Late Carboniferous. The Penglai Movement that occurred in the Jiaobei Belt on the southern margin of the North China Plate is attributed to collision between the North China and Yangtze plates along the Jiaonan Collision Belt. This demonstrates that the continent-continent collision between the North China and Yangtze plates east of the Tan-Lu Fault Zone took place in the Late Carboniferous. The collision caused N-S compression and deformation in the southern margin belt of the North China Plate north of the Qinling-Dabieshan-Jiaonan Collision Belt.

In order to analyze the influence of rigid foot's geometry shape of legged robot on the sinking process in soft soil, MAT 147 material is used as the constitutive model of soil and the dynamic simulation of rigid foot's sinking process is carried out with Multi Material Arbitrary Lagrangian Eulerian(MM-ALE) method. The plate sinking test is simulated with MM-ALE method and the results are compared with the results from empirical formula proposed by Bekker. The results show that the maximum effective stress of soil concentrates at the bottom of the rigid foot near the edge and increases with the sinking of rigid foot, while the overall stress distributions are similar. The sinking depth has great influence on the range of the disturbed soil. The relationship between rigid foot's fillet radius and the stress distribution in the horizontal and vertical direction are studied and the soft soil flow trend are also analyzed. The results indicate that the bigger the fillet radius is, the more uniform the soil stress distribution at the bottom, but it has little influence on the side. Another finding is that the sinking depth has a positive correlation with fillet radius under the same pressure, while the maximum effective stress is opposite.

The aim of this work is to build a cognitive model for the humanoid robot, especially, we are interested in the navigation and mapping on the humanoid robot. The agents used are the Alderbaran NAO robot. The framework is effectively applied to the integration of AI, computer vision, and signal processing problems. Our model can be divided into two parts, cognitive mapping and perception. Cognitive mapping is assumed as three parts, whose representations were proposed a network of ASRs, an MFIS, and a hierarchy of Place Representations. On the other hand, perception is the traditional computer vision problem, which is the image sensing, feature extraction and interested objects tracking. The points of our project can be concluded as the following. Firstly, the robotics should realize where it is. Second, we would like to test the theory that this is how humans map their environment. The humanoid robot inspires the human vision searching by integrating the visual mechanism and computer vision techniques., Comment: This paper has been withdrawn by the author due to the problems in section II