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Silicon-based gallium nitride lasers are considered potential laser sources for on-chip integration. However, the capability of on-demand lasing output with its reversible and wavelength tunability remains important. Herein, a Benz-shaped GaN cavity is designed and fabricated on a Si substrate and coupled to a Ni metal wire. Under optical pumping, excitation position-related lasing and exciton combination properties of pure GaN cavity are studied systematically. Under electrically driven, joule thermal of Ni metal wire makes it easy to change the temperature of the cavity. And then, we demonstrate a joule heat-induced contactless lasing mode manipulation in the coupled GaN cavity. The driven current, coupling distance, and excitation position influence the wavelength tunable effect. Compared with other positions, the outer ring position has the highest lasing properties and lasing mode tuning abilities. The optimized structures demonstrate clear wavelength tuning and an even mode switch. The thermal reduction of the band gap is identified to account for the modification of the lasing profile, but the thermo-optic effect is non-negligible under a high-driven current.

Ocean energy, as a kind of renewable resource, plays an important role in China’s low-carbon development and meeting its goal of “carbon peaking and carbon neutrality”. The paper aims to calculate the cost of ocean power generation in China and make a medium and long-term forecast. Meanwhile, the offshore wind power development experience and the Levelized Cost of Energy (LCOE) cost pricing model is used for analysis and verification. The results shows that it features a high cost without economical efficiency in the initial stage; With the continuous expansion of installed capacity, the cost will be significantly lowered but the economical efficiency is moderate; the cost will fall significantly when the installed capacity reaches to a 100 MW level, and it has strong economical efficiency. The government should provide policy and financial support for ocean power generation industry; enterprises need to strengthen technological innovation and complete the industrial chain to improve the economical efficiency of scale utilization.

Recently, control barrier functions (CBFs), are becoming popular and widely used as a safety-filter of the controller through quadratic programming(QP) optimization framework to ensure the forward invariance of the dynamic systems. However, for sequential safety tasks, the transitions of CBFs are required. To avoid control input discontinuities, firstly, a smooth and speed adjustable transition mechanism by adding a time-varying coefficient of different CBFs is proposed. Moreover, the value of the previous CBF constraint is fixed to reduce the change of the combined CBF constraint. Secondly, a method to integrate different sequential CBFs into a synthetic new one is presented. Through these methods, the smoothness of optimized control inputs can be ensured compared with existing formulations. Simulation results demonstrate that our algorithm provides a smoother transition mechanism to switch different CBFs, and improves the control performance consequently.

The power system contains a variety of uncertainties of different types of sources and loads, as well as random contingencies. Under these uncertainties and rapidly changing operating conditions, traditional rule-based methods cannot dynamically handle short-term voltage instability. To alleviate this situation, this paper proposes a novel power system emergency control scheme using a data-driven method, which combines edge-conditioned graph convolutional networks and deep reinforcement learning. The edge-conditioned graph convolutional network is utilized to extract the characteristics from not only power system nodes but also transmission lines. Deep reinforcement learning is introduced to perform load shedding actions, so as to guarantee the safety and stability of the electric power system. The IEEE 39-bus network is utilized for simulations to validate the effectiveness of the proposed data-driven method. The outcomes demonstrate the proposed method can generate a superior strategy in a number of the short-term voltage instability(STVI) circumstances.

The pipeline support is a complex component structure in liquefied natural gas (LNG) loading arm. In order to study the impact of ultra-low temperature conditions on the mechanical performance of pipeline brackets, the heat transfer analysis and thermal stress calculation of the pipeline support of the LNG loading arm are carried out under low-temperature conditions in this paper. Based on the principle of steady-state heat transfer, the finite element method is used to study the sensitivity of ambient temperature to heat transfer results of pipe support, the results show that the heat dissipated by the duct support is proportional to the temperature difference. The temperature field distribution of the pipe-bundle rib on the duct support under ice-free and ice-covered conditions is analyzed, and two different paths are selected to study the temperature distribution law of the structure, and the conclusion that the ice has the effect of cooling is drawn. Finally, based on the temperature field distribution results obtained by the heat transfer analysis, the low-temperature stress analysis of the pipe support is carried out. According to the thermal stress results, the corresponding improvement measures are proposed. It provides some guidance for the structural design of the loading arm.

Damages such as cracks often occur in engineering structures, and such damages often have the characteristics of time-domain variable stiffness. To effectively identify this kind of damage, a damage detection method based on time domain data and Bayesian fusion is presented in this paper. First, a hybrid model of the AR/ARCH model is used to identify structural nonlinear damage, and a damage indicator is also used: the second-order-variance indicator (SOVI). Although most of the nonlinear damage information is extracted by the indicator SOVI and ARCH model, some nonlinear information is still filtered out by the AR model part. Therefore, a linear cepstral metric indicator (CMI) based on the AR model is introduced to extract the remained nonlinear damage information, and further, the Bayesian fusion theory is applied to combine the results of SOVI and CMI to obtain complete nonlinear damage information and achieve better identification results. Finally, a three-story frame experimental model is used to demonstrate the effectiveness of the Bayesian fusion. Experimental results show that the Bayesian fusion method is superior to SOVI and CMI.

Titanium alloys have limited application in friction and wear environments due to their low surface hardness and poor wear resistance. By preparing a coating that improves wear resistance and high temperature oxidation resistance on the surface of the titanium alloy, the wear and corrosion resistance of the titanium alloy can be significantly enhanced, thereby greatly broadening its application fields and reducing production costs. Starting from the process, this paper systematically explained the current research status of surface laser modification technology at home and abroad, discussed the existing problems and corresponding solutions, and predicted the future development trend of the technology.

Vortex beam carrying orbital angular momentum (OAM) reveals essential application potential in regimes ranging from communication to high-resolution imaging due to the capability to expand channel capacity. However, many current methods for generating vortex beams suffer from narrow bandwidth, low efficiency, and high profile, which undoubtedly will limit their practical application. In this paper, a microwave ultra-wideband single-layer Pancharatnam–Berry metasurface is proposed to convert incident plane waves into vortex waves. The proposed novel stacked-arc-shaped meta-atoms of the metasurface can realize high-performance spin angular momentum-OAM conversion with the efficiency of more than 83% within a considerable bandwidth from 5.85 to 19.56 GHz (fractal bandwidth of 108%), which achieves high-efficiency operation within a wider bandwidth compared to some other wideband metasurface-based vortex beam generator. Three metasurface prototypes for generating vortex beams with the topological charges of l = ±2, −1, −3 respectively are designed. In addition, a metasurface for generating a vortex beam with the topological charge of l = ±2 is fabricated as an example to demonstrate the feasibility and high performance of our vortex beam generator. The generated vortex beams with the mode order of ±2, −1, −3 both in the near-field and the far-field zone are simulated theoretically and the generated vortex beam with the mode order of l = −2 is measured experimentally. The results of the simulation and experiment coincide with each other, which verified the proposed vortex beam generation method successfully. The proposed vortex beam generator is valuable and user-friendly in practical application because of the advantages of low profile, ultra-wide bandwidth, high efficiency, and easy fabrication.

Atmospheric cold plasma jets with various configurations have drawn intense interests in diverse applications, such as surface modification and endoscopic applications. In this paper, a long and ultra-flexible micro-sized cold plasma jet generator is presented and its characteristics are analyzed. The generator mainly consists of two concentric silicone tubes with the inner one acting as the gas channel and the outer one acting as insulating layer of heat and high voltage. Gold thin film was sputtered on the circular surface of inner tube to work as the electrode as well as separation layer of ultraviolet radiation. Electrical, optical and thermal characteristics of this generator were investigated. Cold microplasma jet can be generated and ejected to the ambient air with the length varied from 0.1 m to 2.5 m, and it can impact on the finger without electric and heat sensation. Optical emission spectra analysis indicated that reactive species like OH and O atoms were generated in the plasma. This device exhibits ultra-flexible property which can be arbitrarily bent and plugged into complex and deep environment. Localized internal surface modification of polyvinyl chloride tube using this microplasma jet was also demonstrated and the result showed that surface wettability can be greatly improved after plasma treatment. This generator shows great potential for internal surface processing, plasma endoscopic and maskless lithography applications.

The main interference source of axle counter is the over-current caused by the operation of circuit breaker by intercity train. This paper focuses on the simulation modeling technology of switching over-current of intercity train circuit breaker. Firstly, the mechanism of the interference when the circuit breaker is closed is studied by theoretical analysis; Then, the interference source model is established when the circuit breaker is closed, and the equivalent circuit model of interference path including vehicle body, vehicle body grounding system, traction network and high-voltage cable is obtained through calculation and analysis. The current of transformer primary grounding wire is measured on the actual vehicle, and the accuracy of the model is verified by comparing with the simulation model. Finally, the spectrum characteristics of the interference current in the rail are obtained by Fourier transform. In this paper, a simulation modeling method for analyzing the operating overcurrent of intercity vehicle circuit breaker is proposed, which can effectively evaluate the magnitude of the interference current generated by closing the circuit breaker into the rail, and provide a research basis for the follow-up study of the interference characteristics of the radiation field of rail current on the trackside axle counter.

As a classical problem, network filtering or compression, obtaining a subgraph by removing certain nodes and edges in the network, has great significance in revealing the important information under the complex network. Some present filtering approaches adopting local properties usually use limited or incomplete network information, resulting in missing or underestimating a lot of information in the network. In this paper, we propose a new network filtering and compression algorithm based on network similarity. This algorithm aims at finding a subnetwork with the minimum dissimilarity from the original one. In the meantime, it will retain comprehensively structural and functional information of the original network as much as possible. In detail, we use a simulated annealing algorithm to find an optimal solution of the above minimum problem. Compared with several existing network filtering algorithms on synthetic and real-world networks, the results show that our method can retain the properties better, especially on distance-dependent attributes and network with stronger heterogeneity.

The grid electrode of the grid ionization chamber (GIC) is devoted to eliminating the dependence of the anode pulse amplitude on the initial position and orientation of the ionization. The traditional methods of grid production require cumbersome processes and advanced instruments. In this paper, a bonded stainless steel woven wire mesh (SSWWM) grid electrode manufacturing method is proposed. Compared with the traditional grid electrode, the SSWWM grid features the advantages of simple fabrication, low cost, and high mechanical strength. The energy resolutions of the 40-mesh, 60-mesh and 80-mesh SSWWM grids and orthogonal mesh grid realized by the traditional wire winding method were tested using an 241Am source (around 5.486 MeV). The results show that the optimum energy resolution of the SSWWM and orthogonal mesh grids is approximately 47 keV full width at half-maximum (FWHM). The optimal energy resolutions of the 40-mesh and 60-mesh SSWWM grids are comparable, but the initial operating voltages corresponding to the energy resolution plateau are different, mainly because of the effect of the different geometric parameters of the SSWWM grid on the electron transmittance. A simulation program was used to study the electron transmittance of the SSWWM grid. The simulation results are in agreement with the experimental results, indicating that the simulation program can be used as a reference for the selection of the geometric parameters of the SSWWM grid.

The spreading effect of atmospheric pressure microplasma jets (APμPJ) on the surface of materials will increase the etching area, and controlling the diameter of the jet can improve the precision of surface treatment. In this work, a two-dimensional axisymmetric simulation model is established to analyze the effect of nitrogen (N2) shielding gas on helium (He) from gas dynamics. In addition, by etching the polyethylene terephthalate film, the relationship between the etching effect and aerodynamic analysis is verified. The simulation results are similar to the experimental results, indicating that N2 shielding gas has a focusing effect which is related to the N2 flow rate, distance difference between the inner and outer tubes, and outer tube nozzle diameter. It is hoped that the results of this work can provide a certain reference for the use of shielding gas to control the jet flow of APμPJ.

Skin disease is a common diseases. Although it is very common, the manifestations of skin diseases are various, and the diagnosis process is relatively difficult, and the requirements for dermatologists are also very high. And the recognition efficiency of detection also needs to be improved. To this end, this paper mainly investigates the potential of classifying skin diseases in deep learning convolutional neural networks to enhance the recognition accuracy. The VGG16 neural network was trained using the training data of the ISIC 2019 challenge, and the training data was augmented to increase the accuracy of the model, and accurately classify 3 skin diseases with 97% accuracy. This method can help doctors to make auxiliary diagnosis and provide technical support for skin disease diagnosis.

The process of ionizing normal saline induced by femtosecond laser is studied from the perspective of gas production rate and composition. When the repetition rate is less than 1000 Hz, each laser pulse independently generates ionization gas. At the same time, we discovered the inhibitory effect of meglumini diatrizoici on the ionization process and explained the reasons for this inhibition. Finally, the gas composition proved that the primary gas production mechanism of the femtosecond laser is the decomposition of water molecular, and the composition of the solution after the reaction proved the decomposition effect of the laser on meglumine.

Brain tumor is a serious threat to human health. Because the size and shape of brain tumors can be uneven, irregular and unstructured. Automatic segmentation of tumors from magnetic resonance imaging (MRI) is a challenging task. Brain tumor segmentation using computer-aided diagnosis has important clinical significance for the prognosis and treatment of patients. The traditional U-Net network can not take full advantage of context information, which is easy to cause the loss of effective information of image. Therefore, we propose a multi-scale segmentation method for brain tumors based on U-Net network, in which a multi-scale module for feature extraction is added between down-sampling and up-sampling. The brain tumor public dataset BraTS2020 is used for testing. Dice coefficient was used as the evaluation index, and our experimental method made the average dice of the whole tumor area, core tumor area and enhanced tumor area reach 87.57%, 86.20% and 84.24%, respectively. The experimental results show that the proposed method has comparable precision with typical brain tumor segmentation methods.

Epilepsy, as a common nervous system disease in the world, urgently needs effective methods for diagnosis and treatment. Scalp electroencephalogram (EEG) contains a lot of physiological and pathological information, which plays a very important role in the diagnosis of brain diseases such as epilepsy. At present, the clinical analysis of EEG signal is mainly based on the clinician’s visual analysis, which makes the clinician’s task heavy, and there is no quantitative standard for the analysis results. Therefore, the automatic classification of epileptic EEG signals has great potential in current clinical application. Based on the deep learning VGG16 convolutional neural network model, a method for automatic detection of seizure signals is proposed in this paper. Firstly, the samples are preprocessed, then enter the VGG16 convolutional neural network model for training, and finally input the validation set for validation. The experimental results indicate that this model can distinguish the pre-ictal EEG, interictal EEG and ictal EEG.

Copper fiber reinforced needle-coke/carbon (CF-NC/C) composites with different copper fiber contents have been successfully developed for urban rail pantograph slide block. The mechanical properties of needle coke samples containing 0 wt%, 4 wt%, 8 wt%, 12 wt% and 16 wt% were examined separately. It is found that the presence of needle coke with high aspect ratio, strength and electrical conductivity can greatly improves the physical properties of the pure carbon matrix. Therefore, we have obtained a novel carbon matrix composite. It is also revealed that the optimized CF-NC/C with 5 wt% copper fibers (CF-NC/C-5) composite has outstanding mechanical properties, current-carrying friction wear properties. The density, resistivity, and impact strength of the CF-NC/C-5 composite are 1.8788 g cm−3, 35.18 μΩ·m, 0.16 J cm−2, respectively. In current-carrying friction wear tests (0 A, 5 A, 10 A and 15 A), the CF-NC/C-5 shows an optimum friction wear performance. To avoid agglomeration of copper fibers, the copper fibers are added innovatively during the rolling process and uniformly distributed in the carbon matrix under the tangential force of rolling, which exhibits an improved effect on reinforcing the NC/C composites. Our results greatly advance the development of the needle-coke/carbon composite, which makes the new CF-NC/C composite an ideal candidate for sliding plate material with excellent properties.

Fast-growing food losses and waste (FLW) have caused major environmental issues, yet little is known about the role of trade in the inefficient resource consumption related to FLW. In this study, we estimated the inter-annual water footprints (WFs) and land footprints (LFs) related to FLW in consideration of associated inter-provincial virtual water (VW) and virtual land (VL) flows within China from 2000 to 2017. Additionally, differences between eating at home and out in rural and urban regions were distinguished. The FLW-related WF and LF showed 1.5- and 1.2-fold increasing trends, respectively, over the study period. Eating at home in rural regions caused the most FLW and associated water and land appropriations. Both FLW-related gross inter-provincial VW and VL flows increased by 99% and 22% during the study period, respectively, and inter-provincial VW and VL flows in corresponding FLW-related WF and LF differed significantly. In addition, food losses were found to cause more inefficient resource consumption than food waste. This analysis shows that the substantial role of FLW in shaping the intra-national food-related VW and VL networks, and that the policies for FLW diminution at the food supply chain stage are as important as those at the consumption stage.

We demonstrate two double heterojunction long-wavelength infrared detectors based on InAs/GaSb superlattice on InAs substrates grown by metal-organic chemical vapor deposition. In the two structures, the hole barrier employs a novel InPSb/InAs superlattice to achieve conduction-band alignment, while the electron barrier is InAs/GaSb superlattice to achieve valence-band alignment. Two devices with n-type absorber layer and p-type absorber layer exhibit cut-off wavelengths of ∼10.4 μm and ∼12.2 μm, dark current densities of 9 × 10−4 A cm−2 and 2 × 10−2 A cm−2, and specific detectivities of ∼1.7 × 1010 cm Hz1/2 W−1 and ∼1.5 × 1010 cm Hz1/2 W−1, respectively. The device with n-type absorber has a lower dark current due to the natural valence-band alignment, but it has a low quantum efficiency (QE) resulting from the use of n-type absorber layer. In contrast, the device with p-type absorber has a higher dark current that can be possibly attributed to the conduction-band misalignment, but it achieves a higher QE due to the benefits from the p-type absorber.

Metamorphic testing is an effective method to solve Oracle problems. It is used to test software which is no expected output or the expected output is difficult to construct. However, finding a suitable and effective metamorphic relation in the program is still a very difficult task, usually obtained by domain experts through manual analysis, which greatly reduces the efficiency of software testing. In this work we define a function parameter metamorphic relation from the operation of the function parameter sequence, and preset 10 function parameter metamorphic relation. Because functions with the same structure usually have the same function parameter metamorphic relation, we extract node features and independent path features from the control flow graph, and then create a classification model to judge the similarity between functions. Our experiment includes the evaluation of the prediction model and the prediction of the metamorphic relation on the real function. Good experimental results shows that this method can provides a new way to automated discovery of metamorphic relation.

Laser cladding technology is an advanced surface modification technology. By selecting different parameters and coating materials, the surface hardness and wear resistance of titanium alloys can be effectively improved. The cladding material is a key factor affecting the quality and performance of the cladding layer. Common cladding materials mainly include self-fluxing alloy powder, ceramic powder and rare earth element powder. This paper reviews the current research status of laser cladding material system on titanium alloy, and explains the problems that still need to be solved and puts forward the outlook.

The classification model of the metamorphic relations of the scientific computing program has four categories, of which the code model occupies an important position. We redefine a metamorphic relations, which is single-line metamorphic relations and it exists in the nuclear power program. And it is more comprehensive compared to other metamorphic relations to reflect the internal logic of the program, while node features and path features can maximize the logical structure of the programs. Based on the above situation, we started from the code layer to study the metamorphic relations, put the control flow chart as the bridge of the code and metamorphic relations, extract node features and path features control flowchart and transform the identification problem of metamorphic relations into the problem of predictive model classification. Apply the identified single-line metamorphic relations to the nuclear power field and detect the effectiveness of the software program. The results show that the method is used to enrich the study of the metamorphic relations with the code level, and further improve the degree of automation of metamorphic tests.

In order to solve the problems of high power consumption, complex access network and unstable connection in smart home, a smart home system based on narrowband Internet of things NB-IoT technology is studied. The system uses STM32L431 chip of ST company’s ultra-low power series as the microcontroller, BC95-B5 as the communication module, collects data through a variety of sensors, uploads the collected data information to the remote Huawei cloud server using COAP protocol, and the mobile app accesses the cloud platform and obtains data for display and control. Through the test, the system realizes the function of intelligent control and can greatly improve the intelligent level of home.

This paper describes the output characteristics of DC regulated power supply in spacecraft ground test system and proposes a scheme of DC regulated power supply parallel output with remote sampling. Then the power-on and power-off procedure as well as the characteristics of normal operation in space vehicle using ground power supply are analyzed.The transient characteristics of parallel power supply are summarized. This method with simple circuit connection is able to meet the power supply requirements of spacecraft as well as improve the reliability and security of power supply system. Experimental verification demonstrates the effectiveness of the proposed method. It solves the problem of heavy load energy requirement of spacecraft in ground test and verification stage.

Compared with the traditional recloser fault location without communication channel, feeder automation based on FTU is in line with the development of modern distribution system. FTU plays a key role in the whole system, but the location is inaccurate due to the lack of information caused by FTU itself or communication fault. When using genetic alogrithms for distribution network fault location, the result often converges prematurely or converges to an infeasible solution due to algorithm reasons. Aiming at the above problems, an improved genetic algorithm is proposed for distribution network fault location. Through simulation analysis, it can be found that the improved genetic algorithm has high convergence and good optimal fitness, which can better solve the convergence problems of the unmodified algorithm, which is of great significance for distribution network fault location.

The composition and structure of interstellar dust are important and complex for the study of the evolution of stars and the interstellar medium (ISM). However, there is a lack of corresponding experimental data and model theories. By theoretical calculations based on ab-initio method, we have predicted and geometry optimized the structures of Carbon-rich (C-rich) dusts, carbon (12C), iron carbide (FeC), silicon carbide (SiC), even silicon (28Si), iron (56Fe), and investigated the optical absorption coefficients and emission coefficients of these materials in 0D (zero-dimensional), 1D, and 2D nanostructures. Comparing the nebular spectra of the supernovae (SN) with the coefficient of dust, we find that the optical absorption coefficient of the 2D 12C, 28Si, 56Fe, SiC and FeC structure corresponds to the absorption peak displayed in the infrared band (5–8) μm of the spectrum at 7554 days after the SN1987A explosion. It also corresponds to the spectrum of 535 days after the explosion of SN2018bsz, when the wavelength was in the range of (0.2–0.8) and (3–10) μm. Nevertheless, 2D SiC and FeC correspond to the spectrum of 844 days after the explosion of SN2010jl, when the wavelength is within (0.08–10) μm. Therefore, FeC and SiC may be the second type of dust in SN1987A corresponding to infrared band (5–8) μm of dust and may be in the ejecta of SN2010jl and SN2018bsz. The nano-scale C-rich dust size is ∼0.1 nm in SN2018bsz, which is 3 orders of magnitude lower than the value of 0.1 μm. In addition, due to the ionization reaction in the supernova remnant (SNR), we also calculated the Infrared Radiation (IR) spectrum of dust cations. We find that the cation of the 2D layered (SiC)2+ has a higher IR spectrum than those of the cation (SiC)1+ and neutral (SiC)0+.

We report the growth and characterization of InPSb/InAs superlattice (SL) materials and devices in the short-infrared wavelength range by metalorganic chemical vapor deposition (MOCVD). Good structural quality was achieved with a lattice mismatch of less than 0.09% and smooth surfaces with a roughness of only 0.304 nm. A pin homojunction photodetector with 10 monolayer (ML) InPSb/2 monolayer (ML) InAs SLs on InAs substrate was grown and fabricated. At 77 K, the device demonstrated a 100% cut-off wavelength of ∼2.6 μm, a dark current density of 8.7 × 10−10 A cm−2 at −0.1 V bias voltage, and a specific detectivity of 1.3 × 1013 cm·Hz1/2/W at 2.0 μm.

Barrier property is a characteristic of hollow containers and can be used to meet the need for shelf life of the contents; the hollow container shape is variable, which makes it difficult for overall barrier property testing. Based on this, this paper discusses the common testing methods of water vapor barrier property of hollow containers. Firstly, the advantages and disadvantages of the traditional weighing method and sensor method in testing the water vapor barrier property of containers are compared, typical applications are taken as an example, and finally two new methods, namely electrolytic sensor method and infrared sensor method, which can quickly and accurately test the moisture permeability of hollow containers, are introduced in detail, so as to achieve good and accurate test for various hollow containers, which can provide reference for related industries in selecting testing technologies for container barrier property.

The characteristics of a premixed, swirl methane/air diffusion flame at atmospheric pressure have been measured by filtered Rayleigh scattering (FRS). Three operating conditions are investigated with the equivalence ratios (Φ) of the methane/air flame covered a range of 0.67-0.83. Under each condition, single-shot and averaged FRS images over a region measuring 39.3×65.6 mm2 at seven cross sections (S) of the flame have been collected to demonstrate the flame behaviors. A gradient calculation algorithm is applied to identify reaction zone locations and structures in the instantaneous FRS measurements. Statistical analysis for the mean FRS measurements is performed by means of joint probability density functions (PDFs). The experimental results indicate that thermochemical state of the swirl flame is strongly influenced by equivalence ratio, leading to varieties of flame structures and temperature distributions. The instantaneous FRS results display the momentary flame shapes and rolling vortices. The gradient of the instantaneous FRS images clearly illustrated the characteristics of the reaction zone. The results also demonstrate that FRS can provide detailed insights into the behaviors of turbulent flames.

L-3,4-dihydroxy-phenylalanine (L-dopa) is the most widely used drug in Parkinson’s disease treatment. However, development of cost-effective and high-throughput sensors to accurate enantioselective discrimination of L-dopa and D-dopa remains challenging to date. Herein, on the basis of the peroxidase-mimic activity of chiral Fe x Cu y Se nanoparticles, we demonstrated a novel colorimetric sensor for determination of chiral dopa. The surface chiral ligand, L/D-histidine (L/D-His), endowed the nanozymes with enantioselectivity in catalyzing the oxidation of dopa enantiomers. According to the values of k cat/K m, the efficiency of L-His modified nanoparticles (L-Fe x Cu y Se NPs) towards L-dopa was 1.56 times higher than that of D-dopa. While, D-His can facilely reverse the preference of the nanozyme to D-dopa. On the basis of high catalytic activity and enantioselectivity of L-Fe x Cu y Se NPs in oxidation of L-dopa, the L-Fe x Cu y Se NPs-based system can be utilized for detection of L-dopa. The linear ranges for L-dopa determination were 5 μM–0.125 mM and 0.125 mM–1 mM with a detection limit of 1.02 μM. Critically, the developed sensor has been successfully applied in the quality control of clinical used L-dopa tablets. Our work sheds light on developing simple and sensitive chiral nanomaterials-based sensors for drug analysis.

Poly(3,4-ethylenedioxythiophene) (PEDOT) has proved its quite competitive thermoelectric properties in flexible electronics with its excellent electrical and mechanical properties. Since the early discovery of PEDOT, considerable experimental progress has been achieved in optimizing and improving the thermoelectric properties as a promising organic thermoelectric material (OTE). Among them, theoretical research has made significant contributions to its development. Here the basic physics of conductive PEDOT are reviewed based on the combination of theory and experiment. The purpose is to provide a new insight into the development of PEDOT, so as to effectively design and preparation of advanced thermoelectric PEDOT material in the future.

We demonstrate a high-operating-temperature (HOT) mid-wavelength InAs/GaSb superlattice heterojunction infrared photodetector grown by metal–organic chemical vapor deposition. High crystalline quality and the near-zero lattice mismatch of a InAs/GaSb superlattice on an InAs substrate were evidenced by high-resolution X-ray diffraction. At a bias voltage of –0.1 V and an operating temperature of 200 K, the device exhibited a 50% cutoff wavelength of ~ 4.9 μm, a dark current density of 0.012 A/cm2, and a peak specific detectivity of 2.3 × 109 cm·Hz1/2 /W.

The recently discovered 112-type EuFeAs2 compound that shows complex Eu-spin magnetism provides a new platform to study the interplay between superconductivity (SC) and magnetism in iron pnictide superconductors. In this paper, by substituting Fe with the 4d transition metal (TM) Pd, we have synthesized a series of EuFe1−x Pd x As2 (0 ⩽ x ⩽ 0.08) samples and studied the doping effect on SC and magnetism by means of electrical transport and magnetization measurements. The systematic evolution of the lattice parameters indicates that the Pd atoms have been successfully substituted into the Fe sites. With Pd doping, the Fe-related spin density wave transition at T m Fe in the parent phase is rapidly suppressed, and SC simultaneously emerges, exhibiting a domelike shape with a maximum onset transition temperature T c onset of around 18.5 K at x = 0.04. On the other hand, the Eu-related antiferromagnetic order at T m Eu is suppressed very slowly and persists up to x = 0.08, covering the whole SC dome region. Also, the reentrant spin-glass and spin-reorientation transitions below T m Eu remain unchanged with Pd doping. All these results indicate that the Eu spins have little effect on SC in EuFe1−x Pd x As2. Finally, based on the resistivity and magnetization data, the T − x phase diagram of EuFe1−x Pd x As2 is constructed and compared with those of 3d TMs Co/Ni and La doped ones.

Utilizing first-principles calculations, charge transfer doping process of single layer tin selenide (SL-SnSe) via the surface adsorption of various organic molecules was investigated. Effective p-type SnSe, with carrier concentration exceeding 3.59 × 1013 cm−2, was obtained upon adsorption of tetracyanoquinodimethane or 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane on SL-SnSe due to their lowest unoccupied molecular orbitals acting as shallow acceptor states. While we could not obtain effective n-type SnSe through adsorption of tetrathiafulvalene (TTF) or 1,4,5,8-tetrathianaphthalene on pristine SnSe due to their highest occupied molecular orbitals (HOMO) being far from the conduction band edge of SnSe, this disadvantageous situation can be amended by the introduction of an external electric field perpendicular to the monolayer surface. It is found that Snvac will facilitate charge transfer from TTF to SnSe through introducing an unoccupied gap state just above the HOMO of TTF, thereby partially compensating for the p-type doping effect of Snvac. Our results show that both effective p-type and n-type SnSe can be obtained and tuned by charge transfer doping, which is necessary to promote its applications in nanoelectronics, thermoelectrics and optoelectronics.

Swing platform is widely used to simulate the motion attitude of vehicles, ships and aircraft while carrying large loads. Aiming at the excessive driving force and output power of the driving parts caused by the large load swing platform, a new swing platform which can bear the large load was established. The swing platform is equipped with four spring branch chains between the moving platform and the static platform of the 6-UPS parallel mechanism, so as to offset the gravity of the large load and the inertia force of the large load in the process of motion, and the driving force of each branch chain is reduced. In this paper, the structure of the swing platform is introduced, and the dynamics of the swing platform is modeled using the Newton-Euler dynamics equation. Finally, the driving force of each branch chain of the swing platform is obtained by simulation of the dynamics of the swing platform. The simulation results show that the swing platform with four spring branch chains can effectively reduce the driving force of each branch chain compared with the traditional 6-UPS parallel mechanism swing platform.