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Recently, remote sensing (RS) technology are becoming an increasingly important technology in estimating forest growing stem volume (GSV), and the saturation issue of spectral variables from various optical sensors severely hinders the improvement of mapping forest GSV, especially in the planted forest with high GSV. Forest canopy height is widely considered as one of the major factors to increase the saturation levels in mapping GSV. However, it is rather difficult to invert the forest canopy height without precisely external DEM for large regions. In this study, the canopy height model (CHM) was derived from ZY-3 stereo images with subtracting open-sourced external DEM and the response of saturation levels was analyzed by adding forest height in the planted coniferous forest (Larch and Chinese pine). To further describe the relationships between the forest height and saturation levels, five datasets with five estimation models (Linear, MLR, SVR, KNN, and RF) and three methods of variable selection (Stepwise, LASSO, and Pearson) were applied to estimate the forest GSV using corrected CHM and 49 alternative variables extracted from ZY-3 multispectral images. Meanwhile, a spherical model was employed to quantitatively describe the saturation levels of combined variables. The results showed that values of relative root means square error were decreased from 29.3% to 25% for Larch and from 26.5% to 22.2% for Chinese pine after adding the corrected CHM, respectively. Meanwhile, the saturation level of each combined variable set was successfully determined by the spherical model. The results illustrated that the saturation levels of GSV were significantly increased by adding corrected CHM from open-sourced external DEM. Specially, the averaged saturation levels were increased from 220 m3/ha to nearly 300 m3/ha for Chinese pine and from 150 m3/ha to 220 m3/ha for Larch, respectively. It is proved that ZY-3 stereo and multispectral images have great potential for accurate estimation of forest GSV by delaying the saturation levels using extracted CHM with open-sourced external DEM.

Pre-detonators are commonly used in rotating detonation engine (RDE) experiments. Current experimental studies focus on the performance of pre-detonator while ignoring the influence of pre-detonator on the flow field. In numerical simulations one-dimensional detonation wave is usually used to ignite the fresh gas in RDE. This is a simplification of the pre-detonator used in practical hotfire tests. But the coupling between the pre-detonator and the combustor is ignored. The aim of the present study is to study the influence of pre-detonator on the flow field in the RDE. A model of RDE with a pre-detonator is built, in which three-dimensional numerical simulations fueled with hydrogen/air is performed. The influence of pre-detonator on the combustor in different stages is studied. After initiation, detonation wave from the pre-detonator forms two counter-rotating detonation waves. The tangential installation of pre-detonator fails in directional initiation of detonation wave. The coupling effect is shown as the reflection and expulsion of shock wave. Detonation wave or oblique shock wave in the combustion chamber enters the pre-detonator and turns into shock wave before colliding with the end and re-entering the combustion chamber. Under some circumstances, the reflected shock wave will initiate a detonation wave and affect the wave structure in the combustion chamber. In the stable stage, the reflected shock wave has no effect on the flow field. However, periodic collision of reflected shock wave with detonation wave at the junction causes ablation in long-time experiments. Increasing the axial distance between pre-detonator and injection wall is expected to be a solution for the ablation problem.

The severe shuttle effect and slow kinetics of lithium polysulfide (LiPS) conversion are two major obstacles to the practical application of lithium sulfur batteries. Ultra-thin 2D MoO2 nanosheets (MoO2 NSs) have been synthesized by chemical vapor deposition and then mixed with carbon nanotubes (CNTs) using as coating materials of the Celgard 2400 polypropylene separator to solve these problems. The 2D character of MoO2 NSs produced high surface/volume ratios and abundant active binding sites for anchoring LiPSs. In addition, the partial reduction of MoO2 NSs in a H2/Ar mixture introduced oxygen vacancies in their surface, which acted as catalytic sites for LiPS conversion, while the CNT network ensured rapid electron transfer for LiPS conversion reactions. Symmetric dummy cell tests showed that a 30wt%MoO2/CNT coated separator reduced the energy barrier for Li2S nucleation, and first-principles calculations verified its strong binding energy to entrap LiPSs and increase Li2S precipitation. Because of these features, a cell with a 30wt%MoO2/CNT coated separator had an improved specific capacity of 738 mAh·g−1 at 1 C with a slow decay rate of 0.053% for 800 cycles.

The influence of Mn doping on structure, magnetic behaviors and magnetocaloric effect in TmFeO3 polycrystalline ceramics has been explored. X-ray powder diffraction proves that TmFe1-xMnxO3 (x ≤ 0.3) ceramics maintain an orthorhombic structure, and the space group is Pbnm. Compared with the original TmFeO3 sample, structural parameters change slightly and magnetic properties are effectively tuned with the gradual substitution of Mn at Fe site. The spin reorientation temperature region shifts from 90.3 to 73.2 K for TmFeO3 to 180.0–156.0 K for TmFe0.7Mn0.3O3. Besides, for TmFe1-xMnxO3 (x ≤ 0.3), the maximum magnetic entropy changes dependent on the Mn composition are 6.29 J/kg K, 6.56 J/kg K, 6.79 J/kg K and 7.22 J/kg K for 0–70 kOe, respectively. The refrigeration capacities are 159.3 J/kg, 168.9 J/kg, 176.7 J/kg and 184.4 J/kg, respectively. For a better assessing the magnetocaloric performance of TmFe1-xMnxO3 (x ≤ 0.3), we have calculated the temperature average entropy change, refrigerant capacity and normalized refrigerant capacity, and their values become larger with increasing Mn doping. Our experimental results can provide valuable references for the application and development of RFeO3 (R = rare earth) as multifunctional materials.

Poly(vinyl alcohol) (PVA) is a synthetic and promising film-forming polymer that is usually used in packaging applications. In this study, PVA nanocomposite films with varying amounts of zinc oxide-doped multiwalled carbon nanotubes (MWCNTs-ZnO) were prepared. The tensile strength of the nanocomposite films was 116% higher than that of the PVA film. The thermal stability, water vapor transmission rate, hydrophobicity, and antibacterial activity of the nanocomposite films were better than those of pure PVA. Tests on water loss in vegetables at room temperature revealed that the vegetable wrapped in packaging films could keep more water for more than 4 days. Tests on the shelf life of chicken meat packed in films suggested that the growth of natural microorganisms in raw chicken kept in the preservation storage of the refrigerator could be inhibited for at least 36 h. The findings of this study indicated that nanocomposite MWCNTs-ZnO/PVA films with good transparency had great potential applications in food packaging.

Ferroelectric Rashba semiconductors (FERSCs) have recently attracted intensive attention due to their giant bulk Rashba parameter, αR, which results in a locking between the spin degrees of freedom and the switchable electric polarization. However, the integration of FERSCs into microelectronic devices has provoked questions concerning whether the Rashba effect can persist when the material thickness is reduced to several nanometers. Here we find that αR can keep a large value of 2.12 eV A in the 5.0 nm thick GeTe film. The behavior of αR with thickness can be expressed by the scaling law and provides a 3D thickness limit of the bulk Rashba effect, dc = 2.1 ± 0.5 nm. Finally, we find that the thickness can modify the Berry curvature as well, which influences the polarization and consequently alters the αR. Our results give insight into understanding the factors influencing αR in FERSCs and pave a novel route for designing Rashba-type quantum materials.

We characterize the magnetic interfacial coupling of the Fe/FeGe heterostructure and its influence on the magnetic damping via ferromagnetic resonance in the temperature range of 200-300 K. When the temperature is below the critical temperature of FeGe, the interfacial coupling rises. The strength of the magnetic interfacial coupling is determined as a function of the temperature and reaches up to 0.194 erg/cm2 at 200 K. Meanwhile, the Gilbert damping of the Fe layer is enhanced from 0.035 at 300 K to 0.050 at 200 K. The enhancement is linearly proportional to the strength of magnetic interfacial coupling. We attribute the enhancement to the interfacial coupling that transfers spin angular momentum from Fe to FeGe via the exchange interaction. Our results reveal that the interfacial coupling is an effective approach to inject spin current into the chiral spin texture.

Graphene has many unique properties which have made it a hotbed of scientific research in recent years. However, it is not expected intuitively that the strong effects of the substrate and Coulomb doping in the center of crystal cell on the polaron in monolayer graphene. Here, the interaction energy of surface electron (hole) in the graphene and optical phonons in the substrate, which give rise to weakly coupled polarons, is analyzed in the context of the Coulomb doping. The ground-state energy of the polaron is calculated using the Lee-Low-Pine unitary transformation and linear combination operator method. It is found that the ground-state energy is an increasing function of magnetic field strength, the bound Coulomb potential, and the cutoff wavenumber. Numerical results also reveal that the ground-state energy reduces as the distance between the graphene and the substrate is increased. Moreover, the ground energy level of polaron shows the two (+) and (−) branches and zero-Landau energy (ground) level separation in the graphene-substrate material.

In view of the limited space of offshore platform and the large amount of polymer injection, the dissolution time method, solution viscosity method, conductivity method, undissolved filtration method and falling ball method are used as the rapid detection methods of polymer dissolution. The results show that the error of conductivity method is the largest, and that of dissolution time method is the second, and both methods are time-consuming. Solution viscosity method and insolubles filtration method have small error, but they are time-consuming, especially for offshore platforms, which makes detection inconvenient. The drop ball method is simple in operation and has a small error, so it is a promising method for rapid determination of polymer dissolution time.

Although the magnetic relaxation mechanism in ferromagnetic/nonmagnetic (FM/NM) bilayers has been commendably established, the nonlocal Gilbert damping has been much less addressed in spin valve configurations of FM/NM/FM associated with both the static interlayer exchange coupling and the dynamic coupling. Here, we report the dimensional crossover role of the Pd layer on magnetic relaxation in Fe/Pd/Fe trilayer structures. We identify a pronounced jump of Gilbert damping across the characteristic static interlayer exchange coupling length of Fe/Pd/Fe. The significant enhancement and suppression of Gilbert damping values are ascribed to the entanglement of the dynamics of the two Fe layers mediated by the static exchange coupling and the dynamic exchange coupling. Our work deepens the understanding to manipulate the spin transport and magnetic relaxation via the coherence of spin current.

We used fresh leaves of Sophora japonica L. variety ‘Qingyun 1’ (A0) and 10 superior clones of the same species (A1–A10) to explore leaf morphological characteristics and total particle retention per unit leaf area under natural and artificial simulated dust deposition treatments. Our objectives were to explore the relationship between the two methods and to assess particle size distribution, X-ray fluorescence (XRF) heavy metal content, and scanning electron and atomic force microscopy (SEM and AFM) characteristics of leaf surface microstructure. Using the membership function method, we evaluated the dust retention capacity of each clone based on the mean degree of membership of its dust retention index. Using correlation analysis, we selected leaf morphological and SEM and AFM indices related significantly to dust retention capacity. Sophora japonica showed excellent overall dust retention capacity, although this capacity differed among clones. A5 had the strongest overall retention capacity, A2 had the strongest retention capacity for PM2.5, A9 had the strongest retention capacity for PM2.5–10, A0 had the strongest retention capacity for PM>10, and A2 had the strongest specific surface area (SSA) and heavy metal adsorption capacity. Overall, A1 had the strongest comprehensive dust retention ability, A5 was intermediate, and A7 had the weakest capacity. Certain leaf morphological and SEM and AFM characteristic indices correlated significantly with the dust retention capacity.

Precise synthesis of porous materials is essential for their applications. Self-assembly is a widely used strategy for synthesizing porous materials, but quantitative control of the assembly process still remains a great challenge. Here, a quantitative coassembly approach is developed for synthesizing resin/silica composite and its derived porous spheres. The assembly behaviors of the carbon and silica precursors are regulated without surfactants and the growth kinetics of the composite spheres are quantitatively controlled. This assembly approach enables the precise control of the size and pore structures of the derived carbon spheres. These carbon spheres provide a good platform to explore the structure-performance relationships of porous materials, and demonstrate their pore structure-dependent performance in catalytic water decontamination. This work provides a simple and robust approach for precise synthesis of porous spheres and brings insights into function-oriented design of porous materials.

Graphene-structure GeSe2 nano-films (NFMs) were prepared by chemical vapour deposition. The synthesized GeSe2 NFMs were characterized by using various techniques such as SEM and XRD. Our work provi...

An amorphous GdFeCo film has a spin reorientation transition (SRT) with the temperature varying from 230 K to 300 K. Its magnetization reversal processes have been characterized by the hysteresis loops and first-order reversal curve (FORC) in the vicinity of the SRT temperature. Along with the SRT from out-of-plane to in-plane, the total irreversible components decrease with increasing temperature from 84% (250 K) to 13% (300 K) and the reversal process gradually changes from the pinning-type dominated reversal (250 K) to the nucleation type reversal (270 K), and then to the uniform rotation (300 K). The identification of the magnetization reversal process nearby SRT is important to understand the magnetic properties in the magneto-optical recording materials GdFeCo.

A novel robust quaternized poly(styrene-b-isobutylene-b-styrene) (QSIBS)-based anion exchange membrane (AEM) could be achieved via quaternization and cross-linking reaction of chloromethylated SIBS with amines in the presence of graphene sheets grafted with polydimethylsiloxane arc-bridges (G-g-Arc PDMS). The resulting cross-linked QSIBS/G-g-Arc PDMS composite membranes exhibit significantly high ion conductivity (σ) and dynamic mechanical properties, marked by low methanol permeability, together with improved chemical stability. The σ of composite AEM with 0.25 wt% of graphene loading reached remarkably to 1.81 × 10−2 S cm−1 at 60 °C, compared to that (1.15 × 10−2 S cm−1) of QSIBS. This membrane also behaves high storage modulus of 236 MPa even at 150 °C, while Nafion 115 lost its modulus at 150 °C. The homogeneous dispersion of G-g-Arc PDMS in QSIBS matrix leads to a great decrease in methanol permeability to 3.81 × 10−7 cm2 s−1, which is much lower than that of Nafion 115.

Amorphous Gd65Fe20Al15 and Gd71Fe3Al26 alloys have ever been reported to exhibit giant refrigerant capacity around their magnetic ferromagnetic-paramagnetic phase transition, which is desirable in magnetic refrigeration. In this paper, we have investigated the critical behavior of amorphous Gd65Fe20Al15 and Gd71Fe3Al26 alloys in order to better understand their magnetic phase transition. We compared the critical exponents estimated using modified Arrott plot and Kouvel-Fisher plot methods. The critical exponents obtained by Widom's law are in good agreement with those calculated from critical isotherm analysis. According to the obtained critical exponents, the magnetic properties of these two samples were re-scaled, indicating that the magnetic behavior of these alloys could be expressed by a universal and unified law. By analyzing the effective critical exponents and exchange interaction of the two alloys, we have determined that Gd65Fe20Al15 and Gd71Fe3Al26 exhibit isotropic short-range magnetic interaction and close to the 3D-Heisenberg model.

We have investigated the magnetic properties and the magnetocaloric effect of a GdCoO3−δ epitaxial thin film which was successfully grown on a (001) LaAlO3 substrate by a simple polymer assisted deposition (PAD) method. A paramagnetic–antiferromagnetic magnetic phase transition has been observed in the film at TN (Gd) = 3.2 K. This film exhibits a considerable magnetocaloric effect derived from the interaction between the localized 4f moment of Gd3+ (J = S = 7/2 and L = 0) ions with −ΔSM = 489.75 mJ K−1 cm−3 for a field change of 70 kOe at T = 3.5 K. The significant magnetic entropy change together with the large refrigerant capacity indicate that the GdCoO3−δ epitaxial thin film has potential for cryogenic magnetic cooling of microdevices and microsystems.

Poly(lactic acid) (PLA)/corn stover (CS) composites were prepared by melt blending different proportions of PLA and added CS. PLA was grafted with acrylic acid to improve the compatibility of the matrix with CS. PLA-g-AA interacted well with CS, resulting in a denser composite material with relatively satisfactory hydrophobic properties. The barrier and mechanical properties of composites were studied, and it was found that the barrier and mechanical properties of PLA-g-AA/CS composite materials were significantly improved, especially those with 30 wt% CS provided better tensile properties and elongation at break. The structure at the tensile section of the composite material was observed using SEM. The proper amount of CS had better dispersion in the matrix, and PLA-g-AA could further improve the interfacial bonding force. The crystallization and thermal properties of the composites were analyzed using XRD, DSC, and TGA, and the effect of the CS content on the crystallinity of composites was also studied.

The magnon-magnon coupling in synthetic antiferromagnets advances it as hybrid magnonic systems to explore the quantum information technologies. To induce the magnon-magnon coupling, the parity symmetry between two magnetization needs to be broken. Here we experimentally demonstrate a convenient method to break the parity symmetry by the asymmetric thickness of two magnetic layers and thus introduce a magnon-magnon coupling in Ir-based synthetic antiferromagnets CoFeB(10 nm)/Ir(tIr=0.6 nm, 1.2 nm)/CoFeB(13 nm). Remarkably, we find that the weakly uniaxial anisotropy field (~ 20 Oe) makes the magnon-magnon coupling anisotropic. The coupling strength presented by a characteristic anticrossing gap varies in the range between 0.54 GHz and 0.90 GHz for tIr =0.6 nm, and between nearly zero to 1.4 GHz for tIr = 1.2 nm, respectively. Our results demonstrate a feasible way to induce the magnon-magnon coupling by an asymmetric structure and tune the coupling strength by varying the direction of in-plane magnetic field. The magnon-magnon coupling in this highly tunable material system could open exciting perspectives for exploring quantum-mechanical coupling phenomena., 19 pages, 3 figures

In order to monitor the grinding state of diamond rollers in real-time, the current of the electric spindle of the curve grinder during the diamond roller machining process is taken as the object. The current is collected under the same working conditions, and the current signal is processed by wavelet threshold denoising combined with EMD method. Because the power of the electric spindle is too small, the value of the collected current signal does not change significantly, and it is not enough to judge the grinding state.

Nonmagnetic Rashba systems with broken inversion symmetry are expected to exhibit nonreciprocal charge transport, a new paradigm of unidirectional magnetoresistance in the absence of ferromagnetic layer. So far, most work on nonreciprocal transport has been solely limited to cryogenic temperatures, which is a major obstacle for exploiting the room-temperature two-terminal devices based on such a nonreciprocal response. Here, we report a nonreciprocal charge transport behavior up to room temperature in semiconductor α-GeTe with coexisting the surface and bulk Rashba states. The combination of the band structure measurements and theoretical calculations strongly suggest that the nonreciprocal response is ascribed to the giant bulk Rashba spin splitting rather than the surface Rashba states. Remarkably, we find that the magnitude of the nonreciprocal response shows an unexpected non-monotonical dependence on temperature. The extended theoretical model based on the second-order spin–orbit coupled magnetotransport enables us to establish the correlation between the nonlinear magnetoresistance and the spin textures in the Rashba system. Our findings offer significant fundamental insight into the physics underlying the nonreciprocity and may pave a route for future rectification devices., Most work on nonreciprocal transport is limited to cryogenic temperatures due to the low Rashba spin splitting energy. Here, the authors report a nonreciprocal charge transport behavior up to room temperature in semiconductor α-GeTe with coexisting the surface and bulk Rashba states.

In space environment, the charge will be collected on the surface of the spacecraft by the combination of the surrounding space plasma and photoelectric effect, forming a suspension potential different from the background plasma environment, that is, the surface charging phenomenon. The integrated monitoring system of plasma environment and surface charging includes 4 parts: omnidirectional electron spectrometer, omnidirectional ion spectrometer, surface potential probe and magnetometer. The main function is to detect the space plasma environment and the surface potential on the satellite, and to process, store and transmit the received signals. Ground testing and calibration have been done for all the four detectors, and the results agree well with the designed value.

A fast response high-voltage power supply for the electrostatic deflection system in a low-energy particle spectrometer is designed. The high-voltage power supply uses high-voltage optocouplers as the core amplifying devices, and the output stage is a two-arm push-pull amplifier composed of two high-voltage optocouplers. The experimental results show that the high-voltage power supply can output either positive or negative voltage from the same output port, and the output voltage range is from −3 kV to +3 kV, which can meet the demand of the electrostatic deflection system for the bipolar voltage supply. The adjustment speed of the output voltage is fast. The time of voltage rise or fall does not exceed 1.7 ms, which can speed up the scanning speed of the spectrometer and improve the time resolution. The output stage adopts a push-pull amplification structure, which can improve the temperature stability of the output voltage. The design satisfies the expected performance of the high-voltage power supply for the electrostatic deflection system.

The direction modulation of electrical thruster’s flow is based on magnetic field reforming which leads to the orientation altering of plasma flow ejected from the helicon plasma thruster (HPT). The theoretical simulation and experiments are carried out to analyze the effect of magnetic field shifting for HPT. Simulation work shows that the magnetic field is adjustable when the magnetic coils change their position. All the Permutation and Combination are listed for Three coaxial coils. Plasma density fluctuates according to an accessional magnetic field generated periodically. The plasma density is about 6*1013 m−3 without any modulation and is from 6*1013 m−3 to 1.5*1014 m−3 when the magnetic field introduced. The plasma flow changes its orientation with 60 degree at most with a modulated frequency which reaches 15 Hz. The reason for the increasement of plasma density is the change of orientation of plasma flow, which verifies that the electric-magnetic coil is effective. More specific work of magnetically modulation and integration will be brought into effect.

Based on the wave equation and frequency equation, an analytical model of the ultrasonic vibration squeeze transducer is established, and the structural dimensions of each part of the piezoelectric transducer are calculated. The ANSYS finite element software was used to establish a finite element model on the basis of statics analysis for modal and harmonic response analysis. The traditional analytical method was used to design a 20kHz sandwich piezoelectric transducer for axial vibration. The impedance analyzer is used to measure the transducer, and the impedance-frequency characteristic curve of the transducer is obtained. The results show that the test value is basically the same as the simulation value, and the structural parameters meet the requirements, verifying the rationality of the structure.

The theoretical basis of traditional polymer flooding technology is to improve the viscosity of displacement phase, in order to enhance oil recovery significantly. However, polymer solution is a continuous phase viscous fluid, and it cannot distinguish the large or small pore, which causes the damage in low permeability layer. Furthermore, it leads to the "entry profile inversion" phenomenon and the reduction of injection and liquid production capacity in the field application. Aiming at these problems, a novel particle type microgel (self-adaptive microgel) flooding technology has been developed in recent years. The appearance of self-adaptive microgel is spherical. And it is dispersed in water when displacing oil. Firstly, in this paper its basic physical and chemical properties were studied. Then the pore scale mechanism model of reservoir is used to simulate the flooding process of traditional polymer and self-adaptive microgel, which proves the mechanism advancement of self-adaptive microgel flooding. On this basis, the oil displacement effect evaluation was carried out by the macro physical simulation experiments. Furthermore, this technology has been applied in 8 reservoirs with different conditions. Results show that, self-adaptive microgels have good water swelling properties. They expand rapidly in the initial stage, and then gradually tend to be stable. Secondly, the pore scale simulation experiment shows that, microgel particles present the motion feature of "migration, trapping, deformation" in the porous media. Meanwhile, the particles gather in the larger pore to form the bridge block, and their carrier fluid displace oil in the small pore. So they work in cooperation, which can reduce the flow ability of water phase in the big pore and improve the flow ability of residual oil in small pore. Furthermore, the 3D macro physical simulation experiment shows that, self-adaptive microgel flooding can achieve better oil displacement effect than polymer flooding. Finally, this technology has been applied in 8 oilfields with different conditions, which contains the reservoir temperature from 24 to 126 °C, crude oil viscosity from 1.36 to 156 mPa.s, water cut from 81.4% to 97.5% and recovery degree from 9.55% to 64.4%. And they all obtain good technical and economic effect, with the lowest input-output ratio of 1.67 and the highest of 14.37. Summing up the lab studies and field trial, the new particle-type microgel flooding technology is more efficient and progressiveness. Therefore, its mechanism and performance are further studied in this paper. Meanwhile, its field trial effects are explored and analyzed. The research results provide theoretical basis and technical support for the popularization and application of self-adaptive microgel flooding technology, which may also provide some reference for oil companies to make a wise investment decision in low oil price period.

Research on helicon plasma propulsion mainly includes radio frequency (rf) power coupling, magnetic confinement, discharge mode. The great advantage of helicon plasma propulsion is its high plasma density. Radial velocity can be converted to axial velocity to enhance the thrust with a magnetic nozzle. The plasma density jumps during the plasma discharge is the vital judgment for helicon discharge mode. The article illustrates the apparatus of helicon plasma thruster and points out that there should be two plasma density jumps to verify the helicon discharging mode, and analyzes the plasma density collected by Langmuir probe. Meanwhile, the ion current of plasma flow is collected with retarded potential analyzer, and it clearly shows that there are two jumps in ion currents. The discharging images are taken for the capacitive discharging mode, inductive discharging mode and helicon discharging mode, respectively. Parameters for the discharging mode switch are acquired which will support the development of helicon plasma propulsion.

With the development of electric propulsion technology, the measurement of plasma parameters has been widely used in the field of aerospace. In the process of electric propulsion performance examination and test, the plasma parameters are indispensable to the analysis of electric propulsion performance. Plasma parameters such as electron temperature, plasma density, plasma flux density play important roles in plasma technology, which are the important basis to determine plasma state of electric propulsion. There has a variety of diagnosis method for Plasma electric propulsion. But the radio frequency, electric and magnetic fields often existed in electric propulsion environment. Therefore, It is necessary to use the Retarding potential analyzer (RPA) and Langmuir probe (ALP) together to test the plasma parameters. Experiment data can be mutually verified to effectively improve the accuracy and reliability of test data. The test data of xenon and nitrogen plume obtained in this experiment is of great significance for the in-depth study of helical wave propulsion.

Dynamic magnetization and magnetic anisotropy of Cu/bcc-Co/CoSi2 /Si(0 0 1) system were investigated by Magneto-Optical Kerr Effect (MOKE) analysis and vector network analyzer ferromagnetic resonance (VNA-FMR). Typical fourfold magnetocrystalline anisotropy of bcc Co film and superposed uniaxial magnetic anisotropy were observed. The uniaxial magnetic anisotropy originated from shape anisotropy as confirmed by micromagnetic simulation. The large magnetocrystalline anisotropy results in high resonance frequency even in the zero applied field. The Gilbert damping parameter α obtained by analysis of the dynamic process is close to the theoretically estimated value of bcc phase Co. The Gilbert damping parameter of the bcc-Co film is larger than those of fcc-Co and hcp-Co films. This work indicates the Co damping parameter can be enhanced by using bcc structure, which will help create high-speed magnetoelectronic devices.

Temperature effect of the bound magnetopolaron on the bandgap are discussed in monolayer graphene (MG). The Lee-Low-Pine unitary variational method and linear-combination operator are used to derive the average number of acoustic phonons of ground state and the energy gap of MG. We used quantum statistical theory to study the temperature effect of the bound magnetopolaron on the bandgap in MG. The relationships of the mean number of the acoustic phonons versus the temperature, cut-off wave number (CW), the magnetic field strength are simulated, and the energy gap (EG) of the bound magnetopolaron has a linear relationship with the temperature, the CW, the magnetic field strength, and the Coulomb bound parameter.

The adaptable amorphous carbon films were deposited on As40Se60 glass by radio frequency magnetron sputtering method (rf MS). The effect of CH4 flow rate (0 sccm to 20 sccm) on the structural, optical and mechanical properties of films was investigated by Raman Spectroscopy, X-ray photoelectron spectroscopy (XPS), Scanning Electron Microscope (SEM), UV–vis spectrophotometer, Fourier Transformed Spectroscopy and Continuous Stiffness Measurement. The results reveal that the radical ions and neutrals decomposed from CH4 precursor transform fused aromatic rings clusters of amorphous carbon films to olefinic chains clusters, promote the C H sp3 structure and transforms the amorphous carbon films from diamond-like carbon (DLC) structure to highly hydrogenated graphite-like amorphous carbon (GLCHH) structure. GLCHH films show high visible transmittance, wide optical gap (Eg = 3.30 eV, 20 sccm), well infrared antireflection ability, relative high nanohardness (3.61 GPa, 5 sccm), high ERP (72.5%, 5 sccm), high H/E (0.15, 5 sccm), low residual stress (0.20 GPa, 20 sccm) and well adhesion on As40Se60 glass. Meanwhile, the deposition temperature of GLCHH films (≤115 °C) is much lower than the transition temperature (185 ± 5 °C) of As40Se60 glass, which can minimize the thermal deformation of optical lens made from As40Se60 glass.

The geometries, electronic and magnetic properties of Bi2Cn (n = 1–16) clusters have been systematically studied using density functional theory. The results show that Bi2Cn (n = 1–16) clusters prefer linear structures with the two Bi atoms at the two ends of a linear Cn cluster. We predict that the magic number of Bi2Cn (n = 1–16) clusters should be 4, 6, 8, 11, 13, and 15. According to the Mulliken population analysis, charges always transfer from Bi atoms to C atoms. The total magnetic moment is completely quenched for the Bi2Cn clusters with even n while the odd structures carry a magnetic moment of 2μB, suggesting that the addition of one Bi atom to small BiCn clusters have played an important role in tailoring the host’s magnetism, which will likely have potential applications in new nanomaterials with tunable magnetic properties.

We have investigated the magnetocaloric effects and critical behaviors of Eu2NiMnO6 and Dy2NiMnO6 double perovskite oxides. For a magnetic field varying from 0 to 7 T, the maximum values of the magnetic entropy change ( | Δ S M max | ) reach 4.0 J/kg K and 5.2 J/kg K, and the relative refrigeration capacity (RCP) values are 241.5 J/kg and 385.1 J/kg for Eu2NiMnO6 and Dy2NiMnO6, respectively. The relatively high values of | Δ S M | and RCP suggest that these double perovskite oxides can be used as candidates of magnetic refrigerants working in a wide temperature range. Various techniques such as modified Arrott plot, Kouvel-Fisher method and critical isotherm analysis are used to estimate the critical exponents (β, γ and δ) as well as TC for Eu2NiMnO6. These critical exponents not only obey the Widom scaling relation δ = 1 + γ / β , but also fulfill the scaling equation M ( H , e ) = e β f ± ( H / e β + γ ) where e = (T – TC)/TC, f+ (T > TC) and f- (T

Grafting single end-tethered polymer chains on the surface of graphene is a conventional way to modify the surface properties of graphene oxide. However, grafting arc-like macromolecular bridges on graphene surfaces has been barely reported. Herein, a novel arc-like polydimethylsiloxane (PDMS) macromolecular bridges grafted graphene sheets (GO-g-Arc PDMS) was successfully synthesized via a confined interface reaction at 90 °C. Both the hydrophilic α- and ω-amino groups of linear hydrophobic NH2-PDMS-NH2 macromolecular chains rapidly reacted with epoxy and carboxyl groups on the surfaces of graphene oxide in water suspension to form arc-like PDMS macromolecular bridges on graphene sheets. The grafting density of arc-like PDMS bridges on graphene sheets can reach up to 0.80 mmol g−1 or 1.32 arc-like bridges per nm2 by this confined interface reaction. The water contact angle (WCA) of the hybrid membrane could be increased with increasing both the grafting density and content of covalent arc-like bridges architecture. The superhydrophobic hybrid membrane with a WCA of 153.4° was prepared by grinding of the above arc-like PDMS bridges grafted graphene hybrid, dispersing in ethanol and filtrating by organic filter membrane. This superhydrophobic hybrid membrane shows good self-cleaning and complete oil-water separation properties, which provides potential applications in anticontamination coating and oil-water separation. To the best of our knowledge, this is the first report on the synthesis of functional hybrid membranes by grafting arc-like PDMS macromolecular bridges on graphene sheets via a confined interface reaction.

The magnetic properties and giant magnetic entropy change in gadolinium orthoferrite have been investigated for their potential application as magnetic refrigeration working media. We found GdFeO3 polycrystalline sample exhibits a large magnetic entropy change value (–ΔSM = 50.2 J/kg K at 70 kOe) near the liquid hydrogen temperature, which is much larger than those of other oxide magnetic refrigerators. The large magnetocaloric effect is related to the half-filled 4f electronic state in rare earth-transition oxides. The large values of these parameters, together with negligible hysteresis, suggest that GdFeO3 multiferroic ferrite could be potential materials for magnetic refrigeration in low-temperature region.

Introducing graphene into polymer matrix is an effective way to enhance performances of anion exchange membrane (AEM). However, utilizing the advantages of graphene by physical approach is limited due to the weak interface interaction between graphene and polymer matrix. Herein, we report an effective strategy to covalently bond graphene with polymer matrix to improve the interface interaction and further to improve the properties of AEM. A series of cross-linked quaternized graphene-based hybrid AEM were fabricated by covalently bonding poly (vinylbenzyl chloride) grafted graphene (GN-g-PVBC) copolymer with chloromethyl functionalized poly (styrene-b-isobutylene-b-styrene) (SIBS) through the cross-linker (N,N,N′,N′-tetramethyl-1,6-hexanediamine) by in-situ synthetic approach. The interface interaction between graphene and QSIBS is greatly enhanced according to micromorphology characterization of the hybrid membrane. The cross-linked quaternized hybrid AEM containing 0.55 wt% of GN-g-PVBC exhibits obviously improved dynamical mechanical properties (storage modulus: 418 MPa), ion conductivity (1.81 × 102 S cm−1), methanol barrier property (5.19 × 10−7 cm2 s−1), selectivity (3.49 × 104 S s cm−3) at 60 °C and especially a comparably excellent chemical stability to that of Nafion 115 due to the enhanced interface interaction between graphene and the polymer matrix.

To achieve a rapid and simple detection for the active ingredients of Aescin in the extraction process using near-infrared spectroscopy (NIR) and to realize the state monitoring and quality control of the extraction process. Partial least square regression (PLS) was applied to build the near-infrared calibration models, and the applicability of the model was investigated by predicting the unknown samples in the extraction process. The correlation coefficients of the established Aescin models (A, B, C, D) were 0.9836, 0.9831, 0.9833, 0.9824, and the prediction standard deviations (SEP) were 0.05636, 0.05043, 0.02412, 0.05636, respectively. This study suggests that the proposed model has superior stability and accuracy. NIR spectroscopy technique provides a novel efficient and environmentally friendly approach to the rapid determination of four Aescin key quality indicators (A, B, C, D) in the extraction, which was solved the problem that the lack of state monitoring during the extraction of Aescin, thereby improved the quality of Aescin.

A spindle-like Cu-based metal-organic framework was successfully synthesized under microwave-assisted reaction. When treated as a precursor by pyrolysis of this Cu-MOF at 700 °C under air atmosphere, porous hollow CuO/C composites were prepared and tested as an anode material for lithium-ion batteries (LIBs). The CuO/C electrode manifests an excellent specific capacity of about 789 mAh g −1 at a current of 100 mA g −1 after 200 cycles, together with superior cyclic stability and remarkable rate capacity, which is supposed to benefit from the large accessible surface area and unique hollow interior structure. The remarkable performances make it a promising anode material for LIBs.

We investigate the ultrafast spin dynamics of an antiferromagnet in a ferromagnet/antiferromagnet heterostructure Fe/GdFeO3 via an all-optical method. After laser irradiation, the terahertz spin precession is hard to be excited in a bare GdFeO3 without spin reorientation phase but efficiently in Fe/GdFeO3. Both quasi-ferromagnetic and impurity modes, as well as a phonon mode, are observed. We attribute it to the optical modification of interfacial exchange coupling between Fe and GdFeO3. Moreover, the excitation efficiency of dynamics can be modified significantly via the pump laser influence. Our results elucidate that the interfacial exchange coupling is a feasible stimulation to efficiently excite terahertz spin dynamics in antiferromagnets. It will expand the exploration of terahertz spin dynamics for antiferromagnet-based opto-spintronic devices.

Atomically flat MnSi films were fabricated on Si(1 1 1)-7 × 7 reconstructed surface by molecular beam epitaxy(MBE). Both scanning tunneling microscopy (STM) images and low energy electron diffraction (LEED) patterns demonstrate a well-defined ( 3 × 3 )R30o structure reconstruction. A thickness-driven metal–semiconductor transition in MnSi ultrathin films was observed with decreasing the thickness down to 6 ML (monolayers). The temperature dependence of the resistance and the negative magnetoconductivity suggest the MnSi ultrathin films with thickness lower than 6ML exhibit weak anti-localization (WAL) of two-dimensional (2D) electron systems. This finding that not only advances our understanding of the mechanism of thickness-driven metal–semiconductor transition, but also provides a new strategy to use ferromagnetic semiconductor as spin injector in spintronic devices.

Rechargeable sodium-ion batteries have drawn increasing attention as candidates for the post lithium-ion batteries in large-scale energy storage systems. Layered oxides are the most promising cathode materials and their pure phases (e.g., P2, O3) have been widely investigated. Here we report a series of cathode materials with O3/P2 hybrid phase for sodium-ion batteries, which possesses advantages of both P2 and O3 structures. The designed material, Na0.78Ni0.2Fe0.38Mn0.42O2, can deliver a capacity of 86 mAh g–1 with great rate capability and cycling performance. 66% capacity is still maintained when the current rate reaches as high as 10C, and the capacity retention is 90% after 1500 cycles. Moreover, in situ XRD was performed to examine the structure change during electrochemical testing in different voltage ranges, and the results demonstrate 4 V as the optimized upper voltage limit, with which smaller polarization, better structural stability, and better cycling performance are achieved. The results ob...

A three-dimensional (3D) metal–organic framework (MOF), namely, {[Mn4(PBA)4(H2O)6·5H2O]}n (Mn-PBA), has been successfully constructed from 5-(4-pyridin-3-yl-benzoylamino)-isophthalic acid ligand (H2PBA) and Mn(II) ions under solvothermal condition. Structural analysis reveals that there exist 1D hexagonal channels in the 3D structure along the b-axis. Mesoporous Mn3O4/C composites were fabricated by the direct thermolysis of Mn-PBA at 500 °C under an air atmosphere. When tested as a lithium-ion battery anode material, the Mn3O4/C electrode delivers an excellent capacity of 1032 mAh g–1 at 200 mA g–1 after 500 cycles along with remarkable rate capacity, which is supposed to benefit from the unique microspheres characteristic and large accessible specific area. Owing to the good cycling stability and high capacity, the Mn3O4/C electrode can be regarded as a promising anode material for LIBs.

We have investigated the magnetic properties and magnetocaloric effects (MCEs) of R 2 Mo 2 O 7 ( R = Er, Dy, Gd and Y). Magnetic ground states of R 2 Mo 2 O 7 largely depend on the radius of rare earth ion. Er 2 Mo 2 O 7 , Dy 2 Mo 2 O 7 and Y 2 Mo 2 O 7 with small rare earth radius exhibit spin-glass state around 20 K, while Gd 2 Mo 2 O 7 with larger rare earth radius undergoes a ferromagnetic state below 78 K and a reentrant spin-glass behavior below 34 K. Magnetic phase transition leads to magnetocaloric effect. In particular, a natural table-like - Δ S M and a very large refrigerant capacity ( RC ) value of 94.4 J/kg was observed in a field change of 0–10.5 kOe for Gd 2 Mo 2 O 7 due to two successive magnetic transitions at ∼78 and ∼10 K. These notable magnetocaloric properties make the Gd 2 Mo 2 O 7 a potential candidate for low-field Ericsson-cycle magnetic refrigeration in the low temperature range.

The temperature dependence of magnetic anisotropy of ultrathin Fe film with different thickness epitaxially grown on vicinal Si(111) substrate has been quantitatively investigated using the anisotropic magnetoresistance(AMR) measurements. Due to the effect of the vicinal substrate, the magnetic anisotropy is the superposition of a four-fold, a two-fold and a weakly six-fold contribution. It is found that the temperature dependence of the first-order magnetocrystalline anisotropies coefficient follows power laws of the reduced magnetization m (T)(= M (T)/ M (0)) being consistent with the Callen and Callen's theory. However the temperature dependence of uniaxial magnetic anisotropy (UMA) shows novel behavior that decreases roughly as a function of temperature with different power law for samples with different thickness. We also found that the six-fold magnetocrystalline anisotropy is almost invariable over a wide temperature range. Possible mechanisms leading to the different exponents are discussed.

We report electric-field control of magnetism of (Co/Pt)3 multilayers involving perpendicular magnetic anisotropy with different Co-layer thicknesses grown on Pb(Mg,Nb)O3-PbTiO3 (PMN-PT) FE substrates. For the first time, electric-field control of the interface magnetic anisotropy, which results in the spin reorientation transition, was demonstrated. The electric-field-induced changes of the bulk and interface magnetic anisotropies can be understood by considering the strain-induced change of magnetoelastic energy and weakening of Pt 5d-Co 3d hybridization, respectively. We also demonstrate the role of competition between the applied magnetic field and the electric field in determining the magnetization of the sample with the coexistence phase. Our results demonstrate electric-field control of magnetism by harnessing the strain-mediated coupling in multiferroic heterostructures with perpendicular magnetic anisotropy and are helpful for electric-field modulations of Dzyaloshinskii-Moriya interaction and Rashba effect at interfaces to engineer new functionalities.