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Four quaternary semiconductors with excellent properties as candidate luminescent materials are selected by combining machine learning and first-principles calculations.

Harvesting energy from the human body has attracted substantial attention from industries and academics as it is a promising solution to address the battery life issue. In this paper, we developed a bimorph piezoelectric bending beam-based energy harvester to scavenge energy from the human knee motion for powering body-worn electronics such as smartwatches and health monitors. During walking, the human knee will flex and extend to periodically deform piezoelectric macro fibre composites (MFC) bounded to the bending beam thus generating electricity. The mathematical models of the whole system including the model of the large deflection of the bending beam, movement analysis of the end of the bending beam (slider-crank mechanism), the model of piezoelectric transducers, and measurement of the human knee angle are developed to comprehensively study the harvester. To validate the presented mathematical models, experimental testing on a human body when the subject walks on a treadmill at three different walking speeds is conducted here. The experimental results show good agreement with the simulation results, which indicates that the developed models can characterize the harvester. In addition, the performance of the harvester walking in different contexts is also evaluated. The average power can reach 12.79 mW for level-ground walking, 9.91 mW for stair descending, and 7.70 mW for stair ascending, when walking at a self-selected speed.

Although group 2 Innate Lymphoid Cells (ILC2s) play important roles in driving the pathogenesis of allergic airway inflammation, the molecular mechanisms regulating ILC2 responses remain to be fully elucidated. Adenosine signaling is emerging as an important factor to limit excessive inflammation and tissue damage, its role in ILC2-driven airway inflammation remains to be understood. Here we identify adenosine as a negative regulator of ILC2s and allergic airway inflammation. Elevation of adenosine was observed in lungs after protease papain challenge. Adenosine receptor A2A was abundantly expressed in lung ILC2s. The adenosine analog NECA significantly suppress ILC2s responses and relieved airway inflammation induced by IL-33 or papain. Conversely, blockage of adenosine synthesis by CD73 inhibitor APCP or deficiency of A2A aggravated murine airway inflammation. Adoptive transfer of ILC2s into immunodeficiency NCG mice demonstrated that the regulation of ILC2 by adenosine was cell intrinsic. Mechanistic studies showed that the effects of adenosine on ILC2s were associated with changes in transcriptional profiling, and the elevation of intracellular cAMP and resulted NF-κB downregulation. These observations indicate that adenosine-A2A signaling is a negative regulator of ILC2s, which confers protection against airway inflammation and represents a novel therapeutic target for controlling asthma.

With the rapid evolution of microelectronics, the field of integrated circuits is facing unprecedented challenges. Traditional silicon-based transistors cannot maintain the advantages of high performance during the process of further ultra-scaling due to severe short-channel effects. Two-dimensional (2D) materials are potential channel materials that can replace silicon. Herein, 2D SiP is predicted to have a band gap of 1.49 eV with anisotropic electronic properties by means of first-principles calculations, which is suitable as a channel candidate of transistors. Hence, we investigate the ballistic transport properties of 2D SiP double-gate metal oxide semiconductor field-effect transistors (MOSFETs) by using ab initio quantum transport simulations. Despite anisotropic electronic properties of 2D SiP, the performances of monolayer SiP MOSFETs have weak directional dependence due to high valley degeneracy. The n-MOSFETs with 10-nm gate length can fulfill the high-performance requirements of the International Roadmap for Devices and Systems 2020 Edition (IRDS 2020). However, the p-MOSFETs cannot fulfill the demands of IRDS 2020 because of heavy hole effective masses. Considering the appropriate on-current of 1292 μA/μm for SiP n-MOSFETs, 2D SiP could be utilized as a potential channel material in the next-generation FETs.

All-inorganic lead-free perovskite CsSnBr

Stimuli-responsive liquid crystal elastomers (LCEs), which exhibit sophisticated and versatile shape variations and functions upon stimulations, have constantly interested material science researchers. To date, many challenges still exist in scaling up orientated LCEs with sophisticated physical shapes and multi-functions. Herein, LCEs with various customizable conventional and exotic three-dimensional (3D) shapes and with sizes larger than those previously reported have been prepared by combining magnetic field alignment and soft lithography technology. These LCEs have film, cylinder, ellipsoid, hemispheroid, tube, pyramid, triangle and rectangle frame, grid pattern, cubic frame, and spring shapes. Meanwhile, diversified deformation behaviors such as contraction, expansion, bending, and twisting have been achieved by effectively controlling the alignment directions. Finally, the LCE actuator with hemispheroid shape has been explored for its possible applications in dynamic Braille displays or lenses with adjustable focal length. The simple strategy reported here provides a convenient way to customize multimorphological large-size 3D LCE actuators and their stimuli-responsive deformations. These systems will considerably enlarge the potential applications of LCEs and benefit the development of LCE soft robots and the future special bionic systems.

Group 2 innate lymphoid cells (ILC2s) have emerged as critical mediators in driving allergic airway inflammation. Here, we identified angiotensin (Ang) II as a positive regulator of ILC2s. ILC2s expressed higher levels of the Ang II receptor AT1a, and colocalized with lung epithelial cells expressing angiotensinogen. Administration of Ang II significantly enhanced ILC2 responses both in vivo and in vitro, which were almost completely abrogated in AT1a-deficient mice. Deletion of AT1a or pharmacological inhibition of the Ang II–AT1 axis resulted in a remarkable remission of airway inflammation. The regulation of ILC2s by Ang II was cell intrinsic and dependent on interleukin (IL)-33, and was associated with marked changes in transcriptional profiling and up-regulation of ERK1/2 phosphorylation. Furthermore, higher levels of plasma Ang II correlated positively with the abundance of circulating ILC2s as well as disease severity in asthmatic patients. These observations reveal a critical role for Ang II in regulating ILC2 responses and airway inflammation.

International audience; Nature is providing inspiration for researchers to mimic its functions or existing structures, which could remarkably promote the development of new materials. Here, a large-size honeycomb-shaped liquid crystal elastomer (LCE) actuator with LC orientation along the height of the honeycomb shape is built by combining magnetic field alignment and soft lithography technology. This homeotropic alignment allowed the height contraction of honeycomb and pore size expansion of hexagons in a reversible manner upon temperature variation. Therefore, this LCE actuator can be used as a structure for temperature-gated separation of particles. Another example is an iris-like LCE actuator, which has the capability of adjusting its aperture size with a temperature variation. Our approach provides a simple way to design customizable sophisticated LCE actuators for various potential applications.

Background: The MYC-expressing diffuse large B-cell lymphoma (DLBCL) is one of the refractory lymphomas. The pathogenesis of MYC-expressing DLBCL is still unclear, and there is a lack of effective therapy. In this study, we have explored the clinical significance and the molecular mechanisms of transcription co-activator 4 (PC4) in MYC-expressing DLBCL.Methods: We investigated PC4 expression in 54 cases of DLBCL patients’ tissues and matched normal specimens, and studied the molecular mechanisms of PC4 in MYC-expressing DLBCL both in vitro and in vivo.Results: We reported for the first time that targeting c-Myc could induce autophagic cell death in MYC-expressing DLBCL cell lines. We next characterized that PC4 was an upstream regulator of c-Myc, and PC4 was overexpressed in DLBCL and was closely related to clinical staging, prognosis and c-Myc expression. Further, our in vivo and in vitro studies revealed that PC4 knockdown could induce autophagic cell death of MYC-expressing DLBCL. And inhibition of c-Myc mediated aerobic glycolysis and activation of AMPK / mTOR signaling pathway were responsible for the autophagic cell death induced by PC4 knockdown in MYC-expressing DLBCL. Through the CHIP, DLRTM and EMSA assay, we also found that PC4 exerted its oncogenic functions by directly binding to c-Myc promoters.Conclusions: PC4 exerts its oncogenic functions by directly binding to c-Myc promoters. Inhibition of PC4 can induce autophagic cell death of MYC-expressing DLBCL. Our study provides novel insights into the functions and mechanisms of PC4 in MYC-expressing DLBCL, and suggests that PC4 might be a promising therapeutic target for MYC-expressing DLBCL.

Integral abutment bridges (IABs) have become popular with departments of transportation throughout the United States due to their lower maintenance and construction costs and longer servic...

In recent years, perovskite light-emitting diodes (PeLEDs) have developed rapidly with the highest external quantum efficiency exceeding 20%. Their unbalanced carrier injection and non-radiative recombination assisted by defects lead to the destruction of perovskite crystal structures and poor device stability, which hinders their commercialization process. Thus, to understand the origin of device performance, the key is to figure out the charge-carrier dynamics of the devices. In this review, the charge-carrier dynamics of perovskites are discussed, including radiative and non-radiative recombination, together with the various passivation strategies. Second, we focus on the interfacial carrier dynamics and its influence on device performance. Various strategies to improve the injection balance have been implemented to address the inherent challenges associated with PeLEDs. Last but not least, the characterization techniques of PeLEDs are provided to study the carrier dynamics of PeLEDs.

Due to low power consumption and fast response, magnetorheological (MR) dampers are widely used in various engineering applications. To enhance the performances, efforts have been made to increase the field dependent force with the same power consumption. However, the fluid viscous force is also increased significantly, which is undesirable in practical use. To tackle this problem, the focus of this paper is to design and test a new MR damper with micro-grooves for performance enhancement. First, the detailed design of the proposed MR damper is provided. A prototype of the new MR damper is fabricated. Silicon steel circular rings with thickness of 0.25 mm are installed around the damper piston to form two-layer micro-grooves. Experimental results of the two MR dampers without and with micro-grooves are then compared. The advantages of MR damper with micro-grooves over the one without micro-grooves are validated. The damping force and controllable force range of MR damper with micro-grooves are larger than the one without micro-grooves. When designing MR damper, making micro-grooves can also decrease the increment of fluid viscous force while keeping the same increase of field dependent force. With micro-grooves, the field dependent force is increased by 92.7% with the same power consumption, while the fluid viscous force is increased by 43%.

Active transtibial prostheses, orthoses, and exoskeletons hold the promise of improving the mobility of lower-limb impaired or amputated individuals. Locomotion mode identification (LMI) is essential for these devices precisely reproducing the required function in different terrains. In this study, a terrain geometry-based LMI algorithm is proposed. The environment should be built according to the inclination grade of the ground. For example, when the inclination angle is between 7 degrees and 15 degrees, the environment should be a ramp. If the inclination angle is around 30 degrees, the environment is preferred to be equipped with stairs. Given that, the locomotion mode/terrain can be classified by the inclination grade. Besides, human feet always move along the surface of terrain to minimize the energy expenditure for transporting lower limbs and get the required foot clearance. Hence, the foot trajectory estimated by an IMU was used to derive the inclination grade of the terrain that we traverse to identify the locomotion mode. In addition, a novel trigger condition (an elliptical boundary) is proposed to activate the decision-making of the LMI algorithm before the next foot strike thus leaving enough time for performing preparatory work in the swing phase. When the estimated foot trajectory goes across the elliptical boundary, the decision-making will be executed. Experimental results show that the average accuracy for three healthy subjects and three below-knee amputees is 98.5% in five locomotion modes: level-ground walking, up slope, down slope, stair descent, and stair ascent. Besides, all the locomotion modes can be identified before the next foot strike.

Magnetorheological (MR) fluid, whose rheological properties can be changed reversibly by applied magnetic field, offers superior capabilities and opportunities since its invention. The most crucial feature of MR fluid is its controllable and continuous yield stress. Taking this advantage, MR fluid is gaining popularity in various medical applications to meet their force/torque requirements. In this review article, progress of medical applications of MR fluid in the last two decades are systematically reviewed, mainly focused on six categories: lower limb prosthesis, exoskeleton, orthosis, rehabilitation device, haptic master, and tactile display. With MR fluid, natural and stable limb motions in lower limb prostheses, exoskeletons, and orthoses, flexible muscle trainings in rehabilitation devices, and high transparency and resolution haptic feedback can be realized. Relevant discussions and future perspectives are also provided.

At present, for the widely used Duffing-type bi-stable energy harvesters (D-BEH) with smooth nonlinear forces, there is a trade-off between large equilibrium point coordinates and small potential energy differences. In this study, programmable nonlinear force technologies are used to customize a piecewise bi-stable nonlinear force. Then, a novel piecewise bi-stable energy harvester (P-BEH) is designed to solve this trade-off. The results show that when the coordinate of the equilibrium point is 10 mm, the potential difference of the P-BEH is only 0.05 mJ, while that of the D-BEH is as high as 0.37 mJ. Therefore, the P-BEH can easily overcome the potential difference to make inter-well vibration at the excitation level of 2 m/s2, while the D-BEH can only perform intra-well vibration. Compared with the D-BEH, the P-BEH results in a 46% increase in the peak power and a 767% increase in the bandwidth. Simulation and experiment show that the proposed P-BEH has small potential differences and large equilibrium point coordinates, making it have better energy harvesting performance than the D-BEH.

The modeling of beam mechanisms, especially non-uniform beams, becomes complicated due to the geometric nonlinearity that is proved to be significant with large deflection. A new method, called optimization algorithm-based approach (OABA), is proposed to predict the large deflection of uniform and non-uniform cantilever beams, in which an optimization algorithm is exploited to find the locus of the beam tip. The Euler-Bernoulli beam theory is employed here. With the derived locus of the beam tip, the deflection curve of the cantilever beam can be calculated. The optimization algorithm in this paper is embodied in a particle swarm optimization (PSO) algorithm. Experimental results show that the proposed method can precisely predict the deflection of the uniform and non-uniform cantilever beams. The maximum error is limited to 4.35% when the normalized maximum transverse deflection reaches 0.75. To demonstrate the effectiveness of this method in analyzing compliant mechanisms, we also exploited this method to predict the deformation of a compliant parallel-guiding mechanism.

Making full use of the magnetically controllable rheological properties of magnetorheological (MR) fluid, MR actuators have been applied in many engineering fields. To adapt to different application scenarios, parameters of MR actuators often need to be optimized. Previous MR actuator optimization was focused on finding optimal combinations of geometric dimensions and physical parameters that meet certain requirements. The parts with optimized dimensions were still in regular shape, which might not bring optimal damping performance. Therefore, in this paper, shape optimization of MR damper piston based on parametric curve is performed for the first time. First, the regional magnetic saturation problem in the previous prototype is stated. Then, the MR damper with normal piston is simulated as a reference. Later, Bezier curve, one of the typical parametric curves, is used to form the piston with optimized parameters, and the MR damper with optimized piston is also simulated. Finally, prototypes of the MR dampers with normal and optimized pistons are fabricated and tested. Compared with the MR damper with normal piston, the one with optimized piston has larger field dependent force and total damping force under relatively large current, with about 52% and 24% maximum increasing percentage, respectively. The controllable force range of the MR damper with optimized piston is also larger than that with normal piston.

In this paper, a novel multiple-stable piezoelectric energy harvester with programmable equilibrium point configurations is proposed. Currently, multi-stable energy harvesters have been widely investigated due to possible improvement in performance. However, there are two main problems in the existing literature. The first is that obtaining multiple stable equilibrium points for energy harvesters, such as penta-stable, hepta-stable points, requires a highly complex structural design. The second is that the current design is difficult to arbitrarily specify the number and the coordinates of the equilibrium points, which is helpful for optimizing the performance of the energy harvester. Therefore, we solve these two problems by using programmable nonlinear force technology. As examples, a tri-stable and a hepta-stable energy harvester with specified coordinates of equilibrium points are designed. Both simulations and experiments show that the designs are feasible. Under the acceleration of 2 m/s2 at 7 Hz, the tri-stable energy harvester can charge a 4.7 μF capacitor to 28.6 V, and the hepta-stable energy harvester can charge the capacitor to 21.9 V in 40 s. These voltages are sufficient to power some sensor nodes. In a word, the proposed method is promising in the performance optimization of energy harvesters.

Halide perovskites have been one of the most promising research hotspots in the optoelectronic field. Recently, the issue of ion migration has been proved to be of great significance to their long-term stability and performance of optoelectronic devices. However, the stability of perovskite Cs2SnX6 (X = I, Br, Cl) under the light or electric field conditions has not been explored. In this work, we reported halide ion migration in lead-free all‐inorganic perovskite Cs2SnX6. The calculated formation energy to some degree reveals the concentration of the halide vacancy, which provides the favorable conditions for halide ion migration. Importantly, the theoretical long-term ion migration barriers are investigated to be higher than 1.00 eV, indicating they are relatively stable compared to CsPbX3, and the computational result matches the experimental result with the Nernst−Einstein relation that we adopted. The halogen ion migration energy barrier is 0.91 eV under the bias of 5 V, indicating that the perovskite Cs2SnX6 is relatively stable under a certain electric field. Furthermore, the experimental comparison of XRD results demonstrate that perovskite Cs2SnX6 has no obvious ion migration under certain light conditions. Finally, the analysis results show the Sn–X bond strength that explains the cause of such high barriers. These results reveal the migration mechanism of halide ions and provide new impetus for their optoelectronic applications.

Nonlinear forces have been widely introduced into vibration energy harvesting to improve its performance. Generally, sources of nonlinearity include magnet forces, spring forces, geometric and material nonlinearity, etc. However, these nonlinear forces cannot be manipulated arbitrarily. It is very promising if the nonlinear forces can be customized according to requirements, in which the performance of the energy harvester can be further optimized. Therefore, the purpose of this study is to develop a kind of vibration energy harvester (VEH) that can customize the nonlinear forces. The nonlinear force customization device consists of a pre-compressed spring, a miniature bearing, and a raceway, which are designed according to the nonlinear forces. As an example, the device is installed at the end of a piezoelectric cantilever beam, and mono-stable, bi-stable and tri-stable energy harvesters are customized, respectively. Simulation and experiments prove its effectiveness. The nonlinear force customization device enables designers to obtain the desirable nonlinear forces for the vibration energy harvesters.

Nonlinear forces obtained via springs, magnets, buckling beams, etc., have been widely introduced into vibration energy harvesting, vibration isolation and nonlinear energy sink to improve performance. Although obtaining customized nonlinear forces as desired is difficult, it is quite useful to improve the dynamic performance. Therefore, a device capable of customizing nonlinear forces is developed in this study. The device consists of a pre-compressed spring, a bearing and a raceway, which are designed according to the nonlinear forces to be customized. It is assumed that the nonlinear forces to be customized are continuous (not necessarily smooth). As examples, a hardening nonlinear system, a softening nonlinear system, a bistable system, a tri-stable system, and a piecewise nonlinear system are customized in this study. Simulations and experiments prove its feasibility. The device enables designers to obtain the most suitable nonlinear forces for the dynamic systems. It can be easily applied to energy harvesting, vibration isolation, and nonlinear energy sink, etc.

Due to low power consumption and fast response, magnetorheological (MR) dampers are widely used in various engineering applications. To enhance the performances, efforts have been made to increase the field dependent force with the same power consumption. However, the fluid viscous force is also increased significantly, which is undesirable in practical use. To tackle this problem, the focus of this paper is to design, simulate, and test an MR damper with multi-grooves (small multiple annular flow gaps) on piston for performance enhancement. First, the detailed design of the proposed MR damper is provided. Then, a coupled field model to describe the characteristics of MR fluid in different regions of MR damper is derived. Based on this model, multiphysics simulations are performed using COMSOL Multiphysics. Parametric analysis of the number and width of multi-grooves is also conducted. Experimental results of the two MR dampers without and with multi-grooves are given and compared with the simulation results. The advantages of MR damper with multi-grooves over the one without multi-grooves and the accuracy of the coupled field model are validated by experiments and simulations. This is the first time that the advantages of MR damper with multi-grooves are validated by experiments. Compared with MR damper without multi-grooves, MR damper with multi-grooves has larger damping force and controllable force range, as well as less increment of fluid viscous force while keeping the same increase of field dependent force. The performance of MR damper with multi-grooves could be further improved by increasing the number and decreasing the width of multi-grooves.

When the ship propeller works, besides non-uniform flow field can generate exciting force, shaft vibration can also cause the propeller to produce exciting force. This type of force can usually be expressed as a combination of additional mass force and additional damping force. The purpose of this paper is to study this type of force. First, based on boundary element method (BEM) and combined with rotordynamics theories, the new prediction model of the exciting force induced by shaft vibration is established. Second, the model and codes are validated by some numerical and experiment examples. At last, the axial exciting force induced by the axial shafting vibration is investigated. The results show that when the vibration amplitude is small, or the vibration frequency is low, the nonlinear effect of the wake vortex is weak, so that the exciting force is proportional to the vibration amplitude and square to the vibration frequency. This means that the real part and imaginary part of the exciting force can be equivalent to constant added mass and added damping, respectively. By a series calculation of different propellers, the simplified estimation formula of the axial exciting force in linear state is proposed and validated.

Rotor dynamic balancing technology with online, no start-stop, no trial weights is an important research topic in rotor dynamics, and its key problem is how to identify the rotor unbalance state online. Rotor unbalance parameter identification is often ill-conditioned mathematically, so a small amount of errors such as measurement and modeling will worsen the identification accuracy. For this reason, a new unbalance loads identification method using the rotor finite element (FE) model combined with augmented Kalman filter (AKF) algorithms is proposed. This method is a deterministic-stochastic, time-domain method and is insensitive to measurement and modeling errors. The research results show that the proposed method can well identify the unbalance parameters online and in real time. Meanwhile, the errors of dynamic model and measurement signal could be considered and effectively filtered out in real time, thus the accuracy of unbalance estimation is improved.

The harvesting of energy from human motion for portable and wearable electronic devices has received considerable attention. This letter describes a lightweight macrofiber composite (MFC)-based energy harvester for capturing biomechanical energy through the natural motion of the human knee. In the proposed device, a slider-crank mechanism is used to transform the rotary motion of the knee joint to linear motion, and a bending beam is used to transform the linear motion to a bending motion. When walking, a bending deformation is induced in two MFC slices attached to the bending beam, generating electrical energy. To test the performance of the developed device, treadmill tests at various walking speeds and resistive loads are performed. Experimental results show that the lightweight harvester (weighing just 307 g) can generate 1.60 mW without increasing the human effort required for walking. This is expected to significantly promote the usage of biomechanical energy harvesters.The harvesting of energy from human motion for portable and wearable electronic devices has received considerable attention. This letter describes a lightweight macrofiber composite (MFC)-based energy harvester for capturing biomechanical energy through the natural motion of the human knee. In the proposed device, a slider-crank mechanism is used to transform the rotary motion of the knee joint to linear motion, and a bending beam is used to transform the linear motion to a bending motion. When walking, a bending deformation is induced in two MFC slices attached to the bending beam, generating electrical energy. To test the performance of the developed device, treadmill tests at various walking speeds and resistive loads are performed. Experimental results show that the lightweight harvester (weighing just 307 g) can generate 1.60 mW without increasing the human effort required for walking. This is expected to significantly promote the usage of biomechanical energy harvesters.

The control of the longitudinal pulsating force and the vibration generated is very important to improve the stealth performance of a submarine. Magnetorheological elastomer (MRE) is a kind of intelligent composite material, whose mechanical properties can be continuously, rapidly and reversibly controlled by an external magnetic field. It can be used as variable-stiffness components in the design of a semi-active dynamic vibration absorber (SDVA), which is one of the effective means of longitudinal vibration control. In this paper, an SDVA is designed based on the MRE's magnetic-induced variable stiffness characteristic. Firstly, a mechanical model of the propulsion shaft system with the SDVA is proposed, theoretically discussed and numerically validated. Then, the mechanical performance of the MRE under different magnetic fields is tested. In addition, the magnetic circuit and the overall structure of the SDVA are designed. Furthermore, electromagnetic and thermodynamic simulations are carried out to guarantee the structural design. The frequency shift property of the SDVA is found through dynamic simulations and validated by a frequency shift experiment. Lastly, the vibration absorption capacity of the SDVA is investigated. The results show that the magnetorheological effect of the MRE and the frequency shift of the SDVA are obvious; the SDVA has relatively acceptable vibration absorption capacity.