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This paper proposes a new distributed coordinated control scheme based on heterogeneous roles for Unmanned Aerial Vehicle (UAV) swarm to achieve formation control. First, the framework of the distributed coordinated control scheme is designed on the basis of Distributed Model Predictive Control (DMPC). Then, the effect of heterogeneous roles including leader, coordinator and follower is discussed, and the role-based cost functions are developed to improve the performance of coordinated control for UAV swarm. Furthermore, a group of coordination strategies are proposed for UAVs with different roles to achieve swarm conflict resolution. Numerical simulations demonstrate that the presented distributed coordinated control scheme is effective to formulate and maintain the desired formation for the UAV swarm.

This paper addresses the robust attitude control problem for quadrotors subject to model mismatch and disturbances. A dynamic inversion based attitude control scheme is proposed, which consists of an outer loop attitude controller and an inner loop angular acceleration controller. The attitude controller is designed based on the Nonlinear Dynamic Inversion (NDI) to precisely linearize the nonlinear dynamics between the angular acceleration and the attitude. An onboard actuator model-based Incremental Nonlinear Dynamic Inversion (INDI) controller is designed in the angular acceleration control loop to improve the robustness against the model mismatch and disturbances. Meanwhile, the onboard actuator model with a modified structure eliminates the oscillation phenomenon when the sampling rate of the controller is higher than that of the actuator. Numerical simulations and flight tests demonstrate the effectiveness and robustness of the proposed controller in comparison with the PID controller.

The effect of binding strength of counterions with the polyelectrolyte chain to the swelling of polyelectrolyte brushes is studied, by investigating the swelling of both the polycation and polyanion in response to the variation of the salt concentration under the change of counterion's identity. Two polyelectrolyte brushes grafted on solid substrates are adopted: the cationic poly [2-(methacryloyloxy)ethyltrimethyl ammonium] (PMETA-X, X = F, Cl, Br, and I) and the anionic polystyrene sulfonate (M-PSS, M = Li, Na, K, and Cs). The swelling change with the salt concentration is investigated by ellipsometry, quartz crystal microbalance with dissipation, and dielectric spectroscopy. It is discovered that although the thickness of PMETA-X brushes is larger than that of M-PSS brushes of similar grafting density, the former has much less solvent incorporated than the latter. Such a difference is attributed to the weaker interaction between the PMETA+ chain and its halide counterions than that between the PSS- chain and its alkali counterions, discovered by dielectric spectroscopy. This makes the original charges on the PMETA-X chain less neutralized and therefore have a higher charge density, compared with the M-PSS chain. The results demonstrate that the stronger binding of the counterions to the polyelectrolytes makes the main chains less charged, resulting in the weaker inter-chain electrostatic repulsion and less swelling of the brushes. Investigations into the effect of ion identity show the following order of binding strength: for the cationic PMETA+ chain, F- < Cl- < Br- < I- and for the anionic PSS- chain, Li+ < Na+ < K+ < Cs+.

The dynamics of adsorption and desorption of counterions on a polyelectrolyte chain in aqueous solution is studied at a single molecular level. The investigation is through the process of fluoresce...

An attempt is made to implement a faster level-flight to hover mode transition in tiltrotor’s landing process for the purpose of shortening its landing time. A three-stage tiltrotor landing maneuver is designed, and corresponding control modules and algorithms are created based on the analysis of the flight dynamics and the required actions of tiltrotor’s landing operation. As the altitude control is vital for tiltrotor’s near-ground landing, an Extended State Observer (ESO) control module of the Active Disturbance Rejection Control (ADRC) is designed to reduce altitude fluctuations in the fast mode transition, which makes the designed maneuver workable at very low altitudes. Simulations are conducted to verify the effectiveness of the designed maneuver and the validity of ESO control in various flight conditions. Flight test results that finally prove the effectiveness of the desired fast transition maneuver are reported.

In this work, a porous multilayer graphene film is designed as thermoacoustic speaker using laser scribing technology and a theoretical model based on thermally induced EDFs (Energy Density Fluctuations) is proposed to study its electrical-thermal-acoustic conversion behavior. According to this model, the relationship of the heat energy $Q_{air}$ with the input power is obtained, and the relationship of the sound pressure with the measuring distance, the frequency and the input power is obtained. The measurement of temperature distribution shows that the maximum temperature of graphene film increases linearly with the input power. The measurement of sound pressure shows that SPL (Sound Pressure Level) decreases with the measuring distance. SPL has a rapid growth in low frequency while slow growth in high frequency. SPL has a logarithmic relationship with the input power. The measured results have a good agreement with the theoretical results. The theoretical model based on EDFs has certain reference value for further research on thermoacoustic speakers. This porous multilayer graphene film has the characteristics of one-step fabrication, no mechanical vibration, simple structure and high performance. It could open broad applications in biology, medicine, wearable electronics and other fields.

The paper proposes a new swarm intelligence-based distributed Model Predictive Control (MPC) approach for coordination control of multiple Unmanned Aerial Vehicles (UAVs). First, a distributed MPC framework is designed and each member only shares the information with neighbors. The Chaotic Grey Wolf Optimization (CGWO) method is developed on the basis of chaotic initialization and chaotic search to solve the local Finite Horizon Optimal Control Problem (FHOCP). Then, the distributed cost function is designed and integrated into each FHOCP to achieve multi-UAV formation control and trajectory tracking with no-fly zone constraint. Further, an event-triggered strategy is proposed to reduce the computational burden for the distributed MPC approach, which considers the predicted state errors and the convergence of cost function. Simulation results show that the CGWO-based distributed MPC approach is more computationally efficient to achieve multi-UAV coordination control than traditional method.

An in-line microwave power detection system based on double MEMS cantilever beams is proposed in this work. It realizes the separation of power sense and power detection. A 10% coupling factor can be achieved with the double cantilever beams, and the performance of this in-line microwave power detection system based on double cantilever beams is improved compared with the single beam. The in-line microwave power detection system is designed and fabricated using GaAs MMIC process and MEMS technology. The theoretical models of cantilever beam with different structures are also established and verified. The relationship of return loss, insertion loss and coupling coefficient with the frequency and the capacitance are studied. The measurement results show the return loss is from −9.3dB to −17.7dB, and the insertion loss is from −2.9dB to −1.9dB at 9-11 GHz. The sensitivity of the in-line microwave power detection system is around 1.1 mV/W, 1.45 mV/W, 0.85 mV/W at 9, 10, 11 GHz, respectively. Therefore, this in-line type microwave power detection system can effectively detect microwave power with a high reliability.

A graphene-based flexible filter was obtained via one-step laser heating of a polyimide film. The key parameters of a laser have been confirmed by comparing simulated results and experimental data. High-frequency components of input signals were filtered out effectively for different waveforms, such as sine, rectangular, triangle and pulse waveforms. In order to study filtering performance, this paper focused on amplitude frequency curve, phase frequency curve, transient response and mechanical stability. The phase frequency curve is linear distribution, indicating that it is convenient to control phase shift. The mechanical stability of the device remains good even after 5000 bends, which is unreported in previous work. This paper demonstrated that a graphene-based flexible filter prepared by one-step laser heating has excellent performance and opens new way of thinking about flexible electronics in the future.

The solution-aging treatment parameters, including solution temperature, cooling rate and aging temperature, have significant influences on the microstructures and comprehensive mechanical properties of titanium alloy. In this work, the detailed microevolution behaviors of Ti–10V–2Fe–3Al alloy under different solution and aging conditions have been investigated through a series of heat-treatment experiments. The results of solution-treatment experiments reveal that the content of αp-phase is reduced to zero as the solution temperature is raised to a certain α → β critical transformation point. Recrystallized β-grains can be observed at the solution temperature of 820°C. In addition, the cooling way (air cooling or water cooling) has little influence on the microevolution behaviors for this alloy during the solution-treatment process. As for the solution-aging-treatment experiments, the results reveal that αs-phases are precipitated from the supersaturated β-phase, and the fraction of αs-phase increases with increasing aging temperature. However, the precipitated α-grains intend to coalesce and coarsen as the aging temperature raises above 510°C. Therefore, the advocated solution-aging-treatment program is solution treatment at 820°C with air cooling followed by aging treatment at 510°C with air cooling.

Gliomas account for 75% of the primary malignant brain tumors and a majority of lower-grade gliomas (LGG) inevitably develop into glioblastoma. The dysregulation of lncRNAs play a crucial role in LGG. In the present study, we first screened out six differentially expressed lncRNAs (AC021739.2, AL031722.1, AL354740.1, FGD5-AS1, LINC00844, and NEAT1) based on TCGA and GTEx RNA-seq databases. LncRNA prognostic signature was then established by Kaplan-Meier and multivariate Cox proportional hazards regression, with its predictive value validated by time-dependent receiver operating characteristic (ROC) curves. After lncRNA-miRNA-mRNA regulatory networks were established by Cytoscape 3.7.2, Gene Oncology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed, with results enriched in various malignancy-related functions and pathways. Finally, six putative drugs (irinotecan, camptothecin, mitoxantrone, azacitidine, mestranol, and enilconazole) were predicted by Connectivity Map. In conclusion, we identified a 6-lncRNA prognostic signature with its ceRNA networks, and six candidate drugs against LGG.

The paper proposes a Virtual Target Guidance (VTG)-based distributed Model Predictive Control (MPC) scheme for formation control of multiple Unmanned Aerial Vehicles (UAVs). First, a framework of distributed MPC scheme is designed in which each UAV only shares the information with its neighbors, and the obtained local Finite-Horizon Optimal Control Problem (FHOCP) can be solved by swarm intelligent optimization algorithm. Then, a VTG approach is developed and integrated into the distributed MPC scheme to achieve trajectory tracking and obstacle avoidance. Further, an event-triggered mechanism is proposed to reduce the computational burden for UAV formation control, which takes into consideration the predictive state errors as well as the convergence of cost function. Numerical simulations show that the proposed VTG-based distributed MPC scheme is more computationally efficient to achieve formation control of multiple UAVs in comparison with the traditional distributed MPC method. Keywords: Distributed Model Predictive Control (MPC), Event-triggered mechanism, Formation control, Obstacle avoidance, Unmanned Aerial Vehicles (UAVs), Virtual Target Guidance (VTG)

Polymer electrolytes are essential for next-generation lithium batteries because of their excellent safety record. However, low ionic conductivity is the main obstacle restricting their commercial application. Composites with nanoparticles are a promising route to overcome this obstacle. In this work, lithium polystyrene sulfonate brushes (LiPSS) is anchored to silicon dioxide nanoparticles with chemical bonding using atom transfer radial polymerization (SI-ATRP). The composite polymer electrolytes are made by mixing vinylene carbonate and nanoparticles via a facile in situ polymerization process. The ionic conductivity of composite polymer electrolytes is improved to 7.2 × 10−4 S/cm at room temperature, which is attributed to the low degree of crystallinity of polymer electrolyte and the fast ion transport on the surfaces of polymer brush layers that act as a conductive network. The composite polymer electrolytes show a wide electrochemical window of approximately 4.5 V vs. Li+/Li and excellent cycling performance retention of approximately 95% after 100 cycles at ambient temperature. The results also prove that surface groups of ceramic nanoparticles are an important way to increase the electrochemical properties of composite polymer electrolytes.

An attempt is made to apply modern control technology to the roll and yaw control of a rudderless quad-tiltrotor Unmanned Aerial Vehicle (UAV) in the latter part of the flight mode transition, where aerodynamic forces on the tiltrotor’s wings start to take effect. A predictor-based adaptive roll and yaw controller is designed to compensate for system uncertainties and parameter changes. A dynamics model of the tiltrotor is built. A Radial-Basis Function (RBF) neural network and offline adaptation method are used to reduce flight controller workload and cope with the nonlinearities in the controls. Simulations are conducted to verify the reference model response tracking and yaw-roll control decoupling ability of the adaptive controller, as well as the validity of the offline adaptation method. Flight tests are conducted to confirm the ability of the adaptive controller to track different roll and yaw reference model responses. The decoupling of roll and yaw controls is also tested in flight via coordinated turn maneuvers with different rotor tilt angles. Keywords: Adaptive control, Flight control, Tiltrotor, UAV, VTOL

An original flexible enzyme-free glucose amperometric biosensor based on Cu nanoparticles anchored on laser-induced graphene (Cu NPs-LIG) composite is successfully developed by a simple substrate-assisted electroless deposition (SAED) technique. The as-prepared Cu NPs-LIG sensor demonstrates an excellent glucose sensitivity of 495 μA mM−1 cm−2, ultrafast response time less than 0.5 s and the prominently low detection limit of 0.39 μM. Besides, the sensor shows extraordinary reproducibility, stability and selectivity in glucose sensing. Finally, a possible mechanism of the Cu NPs-LIG sensor for glucose sensing is proposed. Due to the simplicity preparation and performance reliability, the novel flexible Cu NPs-LIG sensor is an attractive candidate for next generation wearable and implantable non-enzymatic glucose diagnostic devices.

A novel optical sensing interface based on nano-opto-electro-mechanical systems (NOEMS) is proposed, in which the light can be coupled with quantum tunneled electrons via weak mechanical coupling. By taking optical pump power and mechanical coupling strength as varying parameters, respectively, bifurcation diagrams of three involved dynamical states of the NOEMS, i.e., optical, electrical and mechanical mode, are calculated, from which an effective coupling region for tunneled electrons and light is revealed. Self-oscillation, transient dynamics and the threshold of the NOEMS are further characterized, and it is found that the effective coupling region has a special transient time. The work sheds light in developing ultra-sensitive photon detectors using physical mechanisms rather than the conventional PN junction based.

In this paper, a new active disturbance rejection control (ADRC) scheme based on swarm intelligent method is proposed for quadrotors to achieve trajectory tracking and obstacle avoidance. First, the finite-time convergent extended state observer (FTCESO) is designed to enhance the performance of ADRC controller. Then, the chaotic grey wolf optimization (CGWO) algorithm is developed with chaotic initialization and chaotic search to obtain the optimal parameters of attitude and position controllers. Further, a novel virtual target guidance approach is proposed to achieve obstacle avoidance for quadrotors. Comparative simulations are presented to demonstrate the effectiveness and robustness of the CGWO-based ADRC scheme and the virtual target guidance approach.

The determination of intrinsic deformation parameters inducing grain refinement mechanism of dynamic recrystallization (DRX) contributes to the relative forming process design. For Ni80A superalloy, the processing maps were constructed by the derivation of the stress-strain data coming from a series of isothermal compression tests at temperatures of 1273-1473 K and strain rates of 0.01-10 s−1. According to the processing maps and microstructural validation, the deformation parameter windows with DRX mechanism were separated in an innovative deformation mechanism map. In addition, the deformation activation energy representing deformation energy barrier was introduced to further optimize such windows. Finally, the enhanced processing maps were constructed and the parameter domains corresponding to DRX mechanism and lower deformation barrier were determined as follows: at ɛ=0.3, domains: 1296-1350 K, 0.056-0.32 s−1 and 1350-1375 K, 0.035-0.11 s−1; at ɛ=0.5, domains: 1290-1348 K, 0.2-0.5 s−1 and 1305–1370 K, 0.035-0.2 s−1; at ɛ=0.7, domains: 1290–1355 K, 0.042–0.26 s−1; at ɛ=0.9, domains: 1298-1348 K, 0.037-0.224 s−1.

To improve the understanding of coupling effect between dynamic recrystallization (DRX) behaviors and flow behaviors of as-cast AlCu4SiMg, a finite element (FE) simulation equipped with the models of DRX evolution was implemented. A series of isothermal compression tests were performed primarily on a Gleeble−3500 thermo-mechanical simulator in a temperature range of 648−748 K and a strain rate range of 0.01−10 s −1 . According to the measured true stress−strain data, the strain hardening rate curves (d σ /d e versus σ ) were plotted to identify the critical strains for DRX initiation ( e c ). By further derivation of the related material constants, the DRX volume fraction equation and the strain for 50% DRX ( e 0.5 ) equation were solved. Accordingly, the aforementioned DRX equations were implanted into the FE model to conduct a series of simulations for the isothermal compression tests. The results show that during the evolution of DRX volume fraction at a fixed strain rate, the strain required for the same amount of DRX volume fraction increases with decreasing temperature. In contrast, at a fixed temperature, it increases with increasing strain rate. Ultimately, the DRX kinetics model of AlCu4SiMg alloy and the consequence of the FE analysis were validated by microstructure observations.

Plants glycerol-3-phosphate dehydrogenase (GPDH) catalyzes the formation of glycerol-3-phosphate, and plays an essential role in glycerolipid metabolism and stress responses. In the present study, the knock-out mutants of cytosolic GPDH (AtGPDHc2) and wild-type Arabidopsis plants were treated with 0, 50, 100, and 150 mmol L−1 NaCl to reveal the effects of AtGPDHc2 deficiency on salinity stress responses. The fluctuation in redox status, reactive oxygen species (ROS) and antioxidant enzymes as well as the transcripts of genes involved in the relevant processes were measured. In the presence of 100 and 150 mmol L−1 NaCl treatments, AtGPDHc2-deficient plants exhibited a pronounced reduction in germination rate, fresh weight, root length, and overall biomass. Furthermore, loss of AtGPDHc2 resulted in a significant perturbation in cellular redox state (NADH/NAD+ and AsA/DHA) and consequent elevation of ROS and thiobarbituric acid-reactive substances (TBARS) content. The elevated ROS level triggered substantial increases in ROS-scavenging enzymes activities, and the up-regulated transcripts of the genes (CSD1, sAPX and PER33) encoding the antioxidant enzymes were also observed. In addition, the transcript levels of COX15, AOX1A and GLDH in gpdhc2 mutants decreased in comparison to wild-type plants, which demonstrated that the deficiency of AtGPDHc2 might also has impact on mitochondrial respiration under salt stress. Together, this work provides some new evidences on illustrating the roles of AtGPDHc2 playing in response to salinity stress by regulating cellular redox homeostasis, ROS metabolism and mitochondrial respiration.

The physical mechanism of multiple modes in dynamics of polyelectrolyte aqueous solutions has been drawing extensive research attention for decades. This unsolved mystery makes it highly desirable to use new techniques to conduct investigations. In this study, dual-color fluorescence cross-correlation spectroscopy is applied to study the dynamics of individual molecules of a model polyelectrolyte, sodium poly(styrene sulfonate), in aqueous solutions. Anticorrelation in the cross-correlation function is discovered as a result of motion coupling due to interchain electrostatic repulsion. After correction, the self-part of the autocorrelation function is obtained, and the calculated mean square displacement data demonstrate a two-stage diffusion process—a fast one at short time lag and a slow one at long time lag. The two processes are attributed to a faster diffusion inside the cage formed by neighboring chains and a slower diffusion beyond the cage. Effects of the salt level and polyelectrolyte concentrati...

Supramolecular polymerization is influenced by many factors, especially the stiffness of the polymers, which is directly related to cyclization of the polymers. We have proposed a supramolecular “ring opening” polymerization system with DNA molecules to study the ring-chain equilibrium of supramolecular polymerization. The molecular weight of the supramolecular polymers was characterized by Asymmetric Flow Field Flow Fractionation, and the diffusion coefficient of the supramolecular polymers was characterized by Fluorescent Correlation Spectra. Tuning the ratio of the “ring opening” strand, the length of the DNA monomers and temperature could change the ring-chain equilibrium, thus influence the molecular weight and diffusion coefficient. This strategy has offered us a useful platform to dig into the kinetic mechanism of supramolecular polymerization.

In this study, we modified the well-known photothermal polydopamine nanoparticles with the poly[(2-methacryloyloxy)ethyl phosphorylcholine-b-(2-dimethylamino)ethyl methacrylate] (PMPC-b-PDMAEMA) diblock copolymers, containing both biocompatible cell membrane phosphorylcholine zwitterions segments and pH-responsive dimethylaminoethyl units on the polymer chains, to achieve both the photothermal property and pH-responsive release behavior. The results showed that the obtained nanoparticles had a narrow size distribution with the diameter about 220 nm. Besides, the modified polydopamine nanoparticles showed enhanced colloidal stability, pH-sensitive drug release behavior, excellent biocompatibility and remarkable near-infrared photothermal property. Thus, it is highly anticipated that PMPC-b-PDMAEMA modified polydopamine nanoparticles can serve as a powerful drug delivery system for combined pH-sensitive drug release and near-infrared photothermal therapeutic.

In this research, an innovative cylindrical automatic battery core oven was designed to avoid the structural deformation that frequently occurs in traditional ovens. The oven could be automatically connected with the electrolyte injection process after baking, achieving improvement in a battery's baking consistency. This contributed to the feasibility of studying the internal heat conduction process of batch battery cores during actual baking processes. A mathematical model of a certain plate battery cell during the baking process was established. The simulation results of the temperature change inside the battery core during the baking process were consistent with the calculation results of the mathematical model. The temperature distribution at each point inside the battery core could be fitted through the thermal conductivity at different temperatures and the temperature distribution between the layers of the battery core. Finally, based on the thermodynamic balance energy conservation method, the relationship between the temperature change inside the battery core and the entire baking process was established. A feasible algorithm for studying the thermal conduction of complex material and internal structure objects in the baking process was obtained. Keywords: Heat and mass transfer, Vacuum drying, Li-ion battery, CFD

The hydroformylation of long chain alkenes catalyzed by a water soluble Rh/TPPTS complex (TPPTS: sodium salt of sulfonated triphenylphosphine) in methanol was investigated. The mixture of rhodium precursor HRh(CO)(TPPTS)3, ligand TPPTS, methanol and a long chain alkene becomes a single phase under reaction conditions, which make the hydroformylation reaction proceed homogeneously. Both the conversion of long chain alkene and the selectivity to aldehydes (including the aldehydes forming methylacetals) could reach up to 97.8% and 97.6%, respectively, with 3323 h−1 of TOF (TOF: turnover frequency is defined as the moles of converted alkene per mole of Rh per hour). After the solvent methanol was removed under the reaction temperature, two phases were formed automatically. The colourless product phase could be efficiently separated from the precipitate rhodium catalyst phase by centrifuge. The catalyst was reused for five times without obvious loss of rhodium and the catalytic activity. The rhodium leaching in product mixture was less than 0.03% of the total rhodium.

This paper is concerned with the inflow problem for one-dimensional compressible Navier-Stokes equations. For such a problem, Huang, Matsumura, and Shi showed in [4] that there exists viscous shock wave solution to the inflow problem and both the boundary layer solution, the viscous shock wave, and their superposition are time-asymptotically nonlinear stable provided that both the initial perturbation and the boundary velocity are assumed to be sufficiently small. The main purpose of this paper is to show that similar stability results still hold for a class of large initial perturbation which can allow the initial density to have large oscillations. The proofs are given by an elementary energy method and our main idea is to use the smallness of the strength of the viscous shock wave and the boundary velocity to control the possible growth of the solutions induced by the nonlinearity of the compressible Navier-Stokes equations and the inflow boundary condition. The key point in our analysis is to deduce the desired uniform positive lower and upper bounds on the density.

Liquid chromatography coupled with mass spectrometry has been used as metabolomics profiling tool to discover and identify the metabolites in metabolic diseases. Osteoporosis (OP) syndrome is a chronic metabolic disease characterized by bone mass reduction and changes in bone microstructure. Psoralea corylifolia Linn. seeds (PCS) have a therapeutic effect on osteoporosis, but their action mechanism and therapeutic target are still unclear. This study aims to explore the metabolic changes of the urine profile in glucocorticoid-induced OP model rats and the therapeutic effect of PCS. High-throughput metabolomics based on the liquid chromatography coupled with mass spectrometry quadrupole time-of-flight mass spectrometry and multivariate data analysis were used to analyze the urine metabolites. The results showed that has an obvious separation between model and control groups. OPLS-DA was used to further analyze and discover substances that contributed to the separation. 42 potential biomarkers and 12 related metabolic pathways were identified in combination with network databases. After the intervention of PCS, 24 biomarkers were significantly regulated, mainly with glycone, serine and threonine metabolism, glutathione metabolism and purine metabolism and other metabolic pathways are related and discovered. This study has proved that PCS has therapeutic effect against OP by regulating that metabolic pathways disturbed in the OP. It provided a basis for the research and future development of new drugs for OP treatment.

The widespread adoption of genetically modified, glyphosate-tolerant corn and soybean varieties in US crop production has led to a dramatic increase in glyphosate usage. Though present at or below regulatory limits currently set for human foodstuffs, the concentration of glyphosate in companion animal feed is currently unknown. In the present study, 18 commercial companion animal feeds from eight manufacturers were analyzed for glyphosate residues using ELISA. Every product contained detectable glyphosate residues in the range of 7.83 × 101–2.14 × 103 μg kg−1 dry weight, with the average and medians being 3.57 × 102 and 1.98 × 102 μg kg−1 respectively. Three products were tested for within-bag variation and six were tested for lot to lot variation. Little within-bag variation was found, but the concentration of glyphosate varied by lot in half of the products tested. Glyphosate concentration was significantly correlated with crude fiber content, but not crude fat or crude protein. Average daily intakes by animals consuming feeds containing the median glyphosate concentration are estimated to result in exposures that are 0.68–2.5% of the Allowable Daily Intake (ADI) for humans in the US and EU, which are 1750 and 500 μg kg−1 respectively. Consumption of the most contaminated feed, however, would result in exposure to 7.3% and 25% of the above ADIs, though the relevance of such an exposure to companion animals is currently unknown. Companion animal feeds contained 7.83 × 101–2.14 × 103 μg kg−1 glyphosate which is likely to result in pet exposure that is 4–12 times higher than that of humans on a per Kg basis.

The thermal and mechanical properties of the chemically imidized polyimide (CIPI) films and thermally imidized polyimide (TIPI) films were investigated systematically. Experimental results indicated that the CIPI films show dramatically enhanced tensile strength and modulus with obviously reduced coefficient of thermal expansion (CTE) in comparison with TIPI films. These enhancements results from the high in-plane orientation and close packing of the CIPI backbones. Compared with thermal imidization which starts at about 140 °C, the chemical imidization activated by acetic anhydride and isoquinoline initiates the cyclization even at room temperature. The resulting imide rings restrict the mobility of polymer chains and lead to the in-plane orientation with solvent evaporation. Additionally, fewer small molecules remain in the films after treated at 120 °C by chemical imidization than by thermal imidization. The polymer chain plasticization caused by the evaporation of small molecules at high temperature is obviously restricted. Moreover, the partially imidized polymer inhibits the decomposition of mainchains that occurs at subsequent high temperature process, being beneficial to the formation of high molecular weight PI films. Hence, chemical imidization pathway shows apparent advantage to produce PI films with great combined properties, including high modulus, strength and toughness, as well as high thermal dimension stability etc.

Funder: Renmin University of China; FundRef: https://doi.org/10.13039/501100004260, This article explores how the western concept of “organic agriculture” has been applied in the traditional Chinese tea industry and how it has been tested during the COVID-19 pandemic. Using in-depth interviews and observations made during 2017–2020, we analyzed different meanings of organic agriculture and values that were given by Chinese farmers who are certified organic producers. Although organic agriculture, particular certified by international certification standards, is a foreign concept, producers invested efforts that go beyond the commercial pursuit for profit. Most importantly, the combination of the reiterated cultural meaning and health benefits of the certified organic tea with the visionary strategy has allowed these producers to shift in a timely manner from export to domestic markets and adapt to the pandemic’s barriers presented to the global trade.

This study investigated the influence of the exogenous application of vitamin B2 (VB2), B12 (VB12), biotin (VH), and nicotinic acid (VPP) on oxygen production in maize (Zea mays L.) seedlings at 5 °C for day 1, 3, 5 and 7. The seeds were soaked in VB2, VB12, VH, and VPP solutions for 24 h at the concentration of 100 mg/L, and control was soaked in distilled water. A total of 50 seeds were used for each treatment in germination boxes was repeated three times. The germination box was placed in a hypothermic incubator for 1, 3, 5, and 7 days in the dark at 5 °C, then moved to a plant growth room and kept for seven days. Compared with the VH and VPP treatments, the VB2 and VB12 treatments had higher thiobarbituric acid reactive substances, proline, and soluble sugars. The VB2 and VB12 treatments also increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) than other treatments. The VB2 and VB12 treatments reduced the contents of hydrogen peroxide (H2O2–), superoxide anion (O2–), and the damage of reactive oxygen species (ROS) to cells, increased the stability of the cell membrane and the content of cell osmoregulation substances. Moreover, VB2 and VB12 had higher seedling growth, germination rate, and index. Treatments VB2 and VB12 could promote maize seed germination and growth under low-temperature stress. Exogenous vitamins in crop production can be a valuable tool for protecting plants against low-temperature stress.

It is well documented that conventional methods such as dynamic light scattering have encountered difficulties in characterizing charged macromolecules and, therefore, it is desirable that new methods and techniques are introduced. With the ultra-high sensitivity, single molecule fluorescence spectroscopy has successfully lowered the detection limit considerably and enabled measurement under extreme dilution conditions—around the concentration of 10−9M—at which the effect of inter-chain electrostatic repulsion is suppressed. Furthermore, the excellent spatial and temporal resolution as well as the capacity of molecular recognition of these methods help in obtaining rich information of charged macromolecules. This paper summarizes the applications of single molecule fluorescence spectroscopy, especially fluorescence correlation spectroscopy and photon counting histogram, in the studies on charged macromolecules in aqueous solutions and plenty of new information has been revealed on the molecular conformation, counterion distribution, and a few important governing factors. The powerfulness and effectiveness of single molecule fluorescence spectroscopy make it promising in the investigations of charged macromolecules.

In this paper, aiming at the discontinuous ignition reentry optimization problem of powered hypersonic vehicle, the reentry trajectory characteristics at different ignition time and ignition duration are analyzed by multiphase Gauss pseudospectral method. Given the attack angle and piecewise linear function described bank angle profiles, the problem of discontinuous ignition for powered reentry trajectory optimization is transformed into a parameter planning problem of ignition time, ignition duration, bank angle parameters and total flight time. By solving the nonlinear multi-constraint parameter optimization problem, the optimal ignition time, ignition duration and bank angle are obtained. Zero value bank angle and real-time calculation bank angle simulation examples are designed to optimize bank angle and ignition commands, respectively. The simulation results show that the discontinuous ignition reentry trajectory optimization problem of powered hypersonic vehicle can be solved by parameterized bank angle profile.

Creating densified and stable liquid is a straightforward strategy for the fabrication of strong and ultra-stable amorphous or glassy materials. The current study has discovered that a liquid polymeric thin film is densified under the application of a high frequency surface acoustic wave (SAW). The experimental evidence is the decrease in film thickness and the increase in refractive index, measured by ellipsometry, of polyisobutylene thin films deposited on the solid substrates, when a high frequency SAW (39.5 MHz) is applied to the system. Further investigations by polarization-resolved single molecule fluorescence microscopy have demonstrated that the rotational motion of fluorescent probes doped inside the liquid film is retarded and the dynamical heterogeneity is reduced. The results demonstrate that the application of SAW of high frequency makes the thin polymeric liquid film densified and more dynamically homogeneous.

The correlation between the water content and protein adsorption on the surface of polymer brushes is investigated quantitatively. Using a number of model systems such as poly N-isopropylacrylamide (PNIPAM), polyethylene glycol (PEG), poly(2-(methacryloyloxy)ethyl phosphorylcholine) (PMPC), poly(2-hydroxyethyl methacrylate) (PHEMA), and poly(2,2,3,4,4,4-hexafluorobutyl)methacrylate (PHFBMA) polymer brushes with various grafting densities, the amount of water hydrodynamically coupled inside the brushes and its correlation with protein adsorption (BSA and Fg proteins as model systems) were determined by quartz crystal microbalance with dissipation (QCM-D) and surface plasma resonance (SPR). The results demonstrate the negative correlation between the water content and protein adsorption - the more water is coupled inside the brushes, the more protein adsorption is suppressed. In particular for PNIPAM brushes with a high enough grafting density and with a water content greater than 250 ng cm-2, the protein adsorption is negligible.

It has long been documented that the reduced viscosity of polyelectrolyte has an anomalous dependence on its concentration, i.e., the Fuoss law. To explore the molecular mechanism, the counterion distribution of sodium polystyrenesulfonate (NaPSS) as a function of concentration is investigated at the single-molecule level. By examination of the fluorescence resonance energy transfer (FRET) between a fluorescence donor on NaPSS chain and an acceptor in the counterions using single-molecule fluorescence spectroscopy, an increase of average counterion–chain distance is discovered upon dilution, indicating the expansion of counterion cloud. By photon counting histogram, an increase of effective charge of the NaPSS chain during dilution is exposed. The variation of these parameters agrees well with that of the reduced viscosity, helping to shed light on the molecular mechanism of the Fuoss law: the expansion of the counterion cloud increases hydrodynamic friction, and the increase of effective charges of NaPSS...

Structure and dynamics inside permanently charged polyelectrolyte brushes, sodium polystyrene sulfonate brushes, during their response to the introduction of external ions (NaCl) are investigated by neutron reflectivity and dielectric spectroscopy. Neutron reflectivity measurements show that the segmental density of the inner part of the brushes decreases and that of the outer part increases when the salt level is tuned from the salt-free condition to a moderate level (

Kinetics of the imidization reaction of poly (amic acid) (PAA) film based on pyromellitic anhydride (PMDA) and 4,4′-diaminodiphenyl ether (ODA) was studied by infrared spectroscopy. Attention is paid to the effect of solvent content inside the sample to the reaction kinetics. The results show that the presence of solvent favors the imidization reaction, rendering a much higher reaction kinetics than the case of without solvent. The data indicates that there is almost one NMP solvent molecule lost per imidization reaction. The kinetics of isothermal imidization reaction exhibits huge heterogeneity and is well-fitted by the Kohlraush-Williams-Watts (KWW) equation, from which the characteristic reaction time and the stretching exponent are determined. Both of them decrease with the increasing of the imidization reaction temperature, demonstrating the reaction is retarded with the proceeding of the reaction together with the creation of bigger dynamical heterogeneity.

Aggregation-induced emission (AIE) materials can exhibit intense luminescence in the aggregated or solid state, which are highly desirable for OLED application. However, only limited research results on developing AIE-active PtII complexes in electroluminescence (EL) application have been reported so far. Herein, a series of AIE-active PtII(C^N)(N-donor ligand)Cl complexes have been developed. Their chemical structures have been determined by NMR, MS, and X-ray crystallography characterization. Theoretical results including the frontier molecular orbitals, the simulated UV–vis spectra, and natural transition orbitals (NTO) have been employed to insightfully interpret their photophysical properties. It has also been found that a much higher degree of molecular aggregation in these PtII complexes should be required to induce phosphorescent AIE than that for the fluorescent AIE behavior. These AIE-active PtII complexes can exhibit very strong emission in poly(methyl methacrylate) (PMMA) films with the phosph...

Hybrid modification processes are used to improve the working surface of 9Cr18Mo bearing steel by plasma immersion ion implantation (PIII) combined with magnetron sputtering (MS). The untreated and treated samples were evaluated by the microhardness and vacuum fiction coefficient tests. Wear morphology of surfaces were also evaluated. It has been found that the microhardness of treated samples increased substantially, and the maximum microhardness was increased 31.9%, the adhesion force at the interface of the film and substrate was improved from 79mN to 107mN, the vacuum friction coefficient was decreased from 0.43 to 0.15, the wear scar diameter was reduced 28.6%. By the comparison of the comprehensive properties of different surface modification processes, hybrid process is better than single process.

Three novel AuI polyynes have been prepared in high yield by copolymerization between an AuI complex precursor and different ethynyl aromatic ligands. The investigation of their photophysical behavior has indicated that forming polyynes through polymerization not only maintains the high transparency of the corresponding AuI polyynes similar to those of their corresponding small molecular AuI acetylides, but also effectively enhances their triplet (T1) emission ability. Critically, owing to their enhanced T1 emission ability, all the AuI polyynes exhibit a stronger optical power limiting (OPL) ability against a 532 nm laser than the corresponding small molecular AuI acetylides. The AuI polyynes based on fluorene and triphenylamine ligands show even better OPL performance than the state-of-the-art OPL material C60, indicating their great potential in the field of laser protection. More importantly, in a prototype OPL device made by doping the fluorene-based AuI polyyne into a polystyrene (PS) solid matrix, substantially improved OPL activity has been observed compared with that in the solution, demonstrating its great potential for practical application. All these results have provided a new strategy to achieve a balance between high OPL activity and good transparency for OPL materials, representing a valuable attempt towards developing new OPL materials with high performance to cope with the key problems in the field of nonlinear optics.

The effective charge and evolution of single chains of a DNA i-motif during its unfolding process are investigated at the single molecule level. Using fluorescence correlation spectroscopy and photon counting histograms, the single chain dimensions and electrical potential of cytosine-rich human telomeric oligonucleotides are monitored, during their unfolding from the i-motif to the random coil state. It is discovered that the effective charge density of the DNA chain is very sensitive to conformation changes and the results remarkably expose the existence of an intermediate state of the unfolding process. A huge difference in pH value exists in the vicinity of the DNA chain and the bulk solution, depending on the salt concentration, as reflected by a down-shift in the pH value of unfolding. The presence of an external salt in the solution helps to stabilize the i-motif structure at low pH values due to the reduction of the effective charge density. It can also destabilize the folded structure in the pH range of the conformation transition due to the elevation of the local pH value, encouraging the deprotonation of the cytosine groups. These results provide new information for understanding the structure and stability of i-motif DNA, and its biological function, as well as the building blocks for smart nanomaterials.

Polymers doped with photosensitive molecules/nanoparticles are believed to be promising optical data storage media. In this communication, a simple method is reported to incorporate multilayers of photosensitive molecules with controlled concentration and spatial distribution into a polymer matrix. This simple hot pressing-based method makes it compatible with existing polymer processing techniques. It is demonstrated that this approach is effective to fabricate free-standing and multi-layered optical data storage media with commonly available polymers. The formation of a multilayer architecture within the polymer matrix involves no adhesives or polymers of other kinds, thus eliminating the concern of refractive index-mismatch between adjacent layers and making the whole material macroscopically homogeneous in structure. When polymers with good ductility and high glass transition temperature are used as the matrix, the macroscopically homogeneous structure can help the material to endure deformation and heat without losing the recorded information.

This paper proposes an event-triggered model predictive control (MPC) scheme for the formation control of multiple unmanned aerial vehicles (UAVs). A distributed MPC framework is designed in which each UAV only shares the information with its neighbors, and the obtained local finite-horizon optimal control problem (FHOCP) can be solved by a swarm intelligent optimization algorithm. An event-triggered mechanism is proposed to reduce the computational burden for the distributed MPC scheme, which takes into consideration the predictive state errors as well as the convergence of cost function. Furthermore, a safe-distance-based strategy for no-fly zone avoidance is developed and integrated into the local cost function for each FHOCP. Numerical simulations show that the proposed event-triggered distributed MPC is more computationally efficient to achieve formation control of multiple UAVs in comparison with the traditional distributed MPC method.

SnS2 material is considered as a promising anode material for Na-ion batteries (NIBs) because of its unique layered structure and high theoretical capacity. However, SnS2 nanosheets are easily overlapped during synthesis and cycling process. Also, they have to experience large volume change during repeated sodiation-desodiation processes. A promising concept is the application of hierarchical hollow structures for improving electrode stability upon cycling. However, they usually rely on template methods that require complex procedures such as chemical etching or calcination to remove inner template. Here, we demonstrate a simple and innovative strategy for fabricating the SnS2 nanosheets assembled hierarchical tubular structures (SnS2 NS ⊂ HTSs) by using cobalt-nitrilotriacetic acid chelate nanowires as soluble template, which makes shell growth and core template dissolution occur simultaneously in one step reaction. Owing to the hollow interior and well separated nanosheets with maximally exposed edges, the SnS2 NS ⊂ HTSs exhibit excellent electrochemical performance. When evaluated as the anode material for NIBs, it delivers a high discharge capacity of 708 mAh g−1 at 50 mA g−1 and still remains up to 414 mAh g−1 after 50 cycles.

A method is presented for three-dimensional (3D) road traffic noise mapping with unstructured surface meshes of buildings and roads. Owing to the ability of the surface mesh to represent objects with high complexity geometry, the method enables 3D noise mapping with realistic building and road models. A road quadrilateral mesh model is built with the coordinates of its vertices captured from the original road triangular mesh. Instead of using the traffic data, we apply the road emission noise levels established by field measurements for a prior classification of roads to determine the basic noise level. An angle scanning based algorithm is developed for modelling 3D noise propagation in urban environments, with obstructions between virtual receiver points and road segment sources are efficiently considered. Verification and validation examples involving high-rise buildings are presented, as well as several 3D noise mapping examples.

The application of polyethylene glycol (donated as PEG), as an environmentally benign solvent instead of water, in rhodium catalyzed hydroformylation of long chain alkenes by using water soluble phosphine BISBIS or TPPTS (TPPTS: sodium salt of sulfonated triphenylphosphine, BISBIS: sodium salt of sulfonated 2,2′-bis(diphenylphosphinomethyl)-1,1′-biphenyl) is herein reported. The conversion of long chain alkenes in PEG-200 could reach above 95.0% after a short reaction time (15 min). In addition, an efficient phase separation and recycling of PEG-200 and catalyst were achieved. The leaching of rhodium into product phase detected by ICP-AES was less than 0.06 wt% of the initial amount.

In this paper, a continuous optical zoom microscopy imaging system based on liquid lenses is proposed. Compared with traditional microscopes, which have discrete magnification, requiring manual conversion of the objective lens to change the magnification, the proposed microscope can continuously change the magnification of the targets in real-time. An adaptive zoom microscope, a liquid lens driving board, a microscope bracket, an adjustable three-dimensional stage and a light source are stacked to form the main framework of the continuous optical zoom microscopy imaging system. The adaptive zoom microscope which is composed of four electrowetting liquid lenses and six glass lenses form the main imaging element of the microscope. By changing the driving voltage which is applied to the four liquid lenses, the focal length of the liquid lenses can be modulated to achieve continuous zooming. By contrast, in traditional microscopes, the zooming process can only be achieved by rotating the eyepieces at different magnifications. At a fixed working distance, the magnification of the proposed microscope can change continuously from ∼9.6× to ∼22.2× with a response time of ∼50ms. Moreover, an axial depth scanning of ∼1000µm can be achieved without any mechanical movement. Our experiments proved that the microscope has stable performance and high consistency during zooming. Therefore, the proposed microscope has obvious advantages over the traditional microscopes in observing dynamic samples with different magnifications and can be commercialized for further expanding the applications in biochemical and pathological analysis.

Flexible and wearable pressure sensors are attracting a considerable interest for the essential requirements of personalized health monitoring and electronic skin in next-generation electronics. However, reliable and cost-effective preparation of high-performance pressure sensors remains a challenge. Herein, a novel flexible asymmetric pressure sensor composed of multi-walled carbon nanotubes (MWCNTs) and laser-induced graphene (LIG) has been developed. The key resistance sensitive material of MWCNTs-embedded LIG (MWCNTs/LIG) with an interconnected hierarchical microstructure is fabricated by a simple, convenient and efficient laser direct writing (LDW) technique. By virtue of this designed three-dimensional crosslinked structure, MWCNTs/LIG hybrid endows the asymmetric pressure sensor with combined excellent characteristics of a high sensitivity (2.41 kPa−1), prominent detectable limit (about 1.2 Pa), very responsive recovery (2 ms), and remarkable durability (>2 000 cycles). This high-performance MWCNTs/LIG asymmetric pressure sensor can clearly detect various subtle human motions (such as breath, vocal vibration, finger movement, and wrist pulse) in real time. Moreover, the integrated MWCNTs/LIG sensory array has a very good multi-point recognition capability. Benefit from its outstanding sensing performances, the as-fabricated pressure sensor has vital inspiration for widespread practical applications in human monitoring of physiological activities, electronic skin, and other wearable fields.

The inhibition of glycosidase activity is regarded as an effective treatment for diabetes mellitus. Bilberry (Vaccinium myrtillus L.) fruit has a high content of anthocyanins with various biological activities. The objective of this study was to investigate the inhibitory activity of anthocyanin-rich bilberry extract (BE) on α-glucosidase and α-amylase and their interaction mechanisms in vitro. The IC50 values of BE with regard to α-glucosidase and α-amylase inhibition were 0.31 ± 0.02 and 4.06 ± 0.12 mg/mL, respectively. The enzyme kinetics revealed that BE acts as a mixed-type inhibitor against α-glucosidase and α-amylase. Moreover, the fluorescence of two glucosidases showed significant quenching by BE. FTIR spectra and differential scanning calorimetry (DSC) indicated that BE changed the enzyme structure and decreased its stability. A morphological observation of starch granules found that BE inhibited the activity of α-amylase to postpone the hydrolysis of starch. Furthermore, the in vivo study further showed that BE had a hypoglycaemic effect. The most suitable conformation (main anthocyanidins of BE) and optimal binding site (α-glucosidase, α-amylase) were assayed by molecular docking. In conclusion, this study revealed that BE could be a potential glycosidase inhibitor.