教育、科技、人才一体布局与科学基金发展战略

教育、科技、人才一体布局的统筹部署已经成为全面建设社会主义现代化国家的基础性、战略性支撑,深刻理解与把握教育、科技、人才一体布局重大意义对开展基础研究资助至关重要。在厘清一体布局对基础研究资助新要求的前提下,明确基础研究资助在科学研究、科学教育与人才培养有机结合中的定位和作用,完善国家自然科学基金资助管理体系,探索落实一体布局的着力点,从而提出新时代科学基金发展的战略思路,为教育强国、科技强国、人才强国建设提供源头支撑。

OsMYB84,a transcriptional regulator of OsCOPT2 and OsHMA5,modulates copper uptake and transport and yield production in rice

Transcription factors regulating crop uptake and translocation of the micronutrient Cu have not been identified.We isolated a novel R2R3-MYB transcription factor,OsMYB84,and showed that it was a positive regulator involved in uptake and transport of Cu via activation of OsCOPT2 and OsHMA expression.OsMYB84 was highly expressed in roots and anthers and induced by Cu.Overexpression of OsMYB84 promoted uptake and root-to-shoot translocation of Cu in rice,facilitated Cu distribution into grain and increased grain yield.In contrast,mutation of OsMYB84 reduced Cu concentration in xylem sap.OsMYB84 bound to the promoter region of OsCOPT2 and OsHMA5 and upregulated their expression.OsCOPT2 mutants showed reduced uptake of Cu and OsHMA5 overexpression lines showed increased root-to-shoot translocation of Cu.

Mapping the antiparallel aligned domain rotation by microwave excitation

The evolution process of magnetic domains in response to external fields is crucial for the modern understanding and application of spintronics.In this study,we investigated the domain rotation in stripe domain films of varying thicknesses by examining their response to microwave excitation in four different orientations.The resonance spectra indicate that the rotation field of stripe domain film under an applied magnetic field approaches the field where the resonance mode of sample changes.The saturation field of the stripe domain film corresponds to the field where the resonance mode disappears when measured in the stripe direction parallel to the microwave magnetic field.The results are reproducible and consistent with micromagnetic simulations,providing additional approaches and techniques for comprehending the microscopic mechanisms of magnetic domains and characterizing their rotation.

Reconfigurable and polarization-dependent optical filtering for transflective full-color generation utilizing low-loss phase-change materials

All-dielectric metasurface, which features low optical absorptance and high resolution, is becoming a promising candidate for full-color generation. However, the optical response of current metamaterials is fixed and lacks active tuning. In this work, we demonstrate a reconfigurable and polarization-dependent active color generation technique by incorporating low-loss phase change materials(PCMs) and CaF_2 all-dielectric substrate. Based on the strong Mie resonance effect and low optical absorption structure, a transflective, full-color with high color purity and gamut value is achieved. The spectrum can be dynamically manipulated by changing either the polarization of incident light or the PCM state. High transmittance and reflectance can be simultaneously achieved by using low-loss PCMs and substrate. The novel active metasurfaces can bring new inspiration in the areas of optical encryption, anti-counterfeiting, and display technologies.

High-performance GaSb planar PN junction detector

This paper examines GaSb short-wavelength infrared detectors employing planar PN junctions. The fabrication was based on the Zn diffusion process and the diffusion temperature was optimized. Characterization revealed a 50% cut-off wavelength of 1.73 μm, a maximum detectivity of 8.73 × 10^(10) cm·Hz^(1/2)/W, and a minimum dark current density of 1.02 × 10^(-5) A/cm^(2).Additionally, a maximum quantum efficiency of 60.3% was achieved. Subsequent optimization of fabrication enabled the realization of a 320 × 256 focal plane array that exhibited satisfactory imaging results. Remarkably, the GaSb planar detectors demonstrated potential in low-cost short wavelength infrared imaging, without requiring material epitaxy or deposition.

A Novel Parameter-Optimized Recurrent Attention Network for Pipeline Leakage Detection

Accurate detection of pipeline leakage is essential to maintain the safety of pipeline transportation.Recently,deep learning(DL)has emerged as a promising tool for pipeline leakage detection(PLD).However,most existing DL methods have difficulty in achieving good performance in identifying leakage types due to the complex time dynamics of pipeline data.On the other hand,the initial parameter selection in the detection model is generally random,which may lead to unstable recognition performance.For this reason,a hybrid DL framework referred to as parameter-optimized recurrent attention network(PRAN)is presented in this paper to improve the accuracy of PLD.First,a parameter-optimized long short-term memory(LSTM)network is introduced to extract effective and robust features,which exploits a particle swarm optimization(PSO)algorithm with cross-entropy fitness function to search for globally optimal parameters.With this framework,the learning representation capability of the model is improved and the convergence rate is accelerated.Moreover,an anomaly-attention mechanism(AM)is proposed to discover class discriminative information by weighting the hidden states,which contributes to amplifying the normalabnormal distinguishable discrepancy,further improving the accuracy of PLD.After that,the proposed PRAN not only implements the adaptive optimization of network parameters,but also enlarges the contribution of normal-abnormal discrepancy,thereby overcoming the drawbacks of instability and poor generalization.Finally,the experimental results demonstrate the effectiveness and superiority of the proposed PRAN for PLD.

Effects of rod radius and voltage on streamer discharge in a short air gap

Streamer discharge is the inaugural stage of gas discharge,and the average electron energy directly determines the electron collision reaction rate,which is a key parameter for studying streamer discharge.Therefore,taking into account the average electron energy,this work establishes a fluid chemical reaction model to simulate and study the course of evolution of a streamer discharge in a 5 mm rod–plate gap,considering 12 particles and 27 chemical reactions.It introduces the electron energy drift diffusion equation into the control equation,and analyzes the temporal and spatial changes of average electron energy,electric field intensity and electron density with change in rod radius and voltage.The effects of voltage and rod radius on the course of streamer discharge can be reflected more comprehensively by combining the average electron energies.Three different values of 0.3 mm,0.4 mm and 0.5 mm are set for the rod radius,and three different values of 5 k V,6 k V and 7 k V are set for the voltage.The influence of an excitation reaction on the streamer discharge is studied.The findings indicate that,as voltage raises,the streamer head’s electron density,electric field and average electron energy all rise,and the streamer develops more quickly.When the rod radius increases,the electron density,electric field and average electron energy of the streamer head all decrease,and the streamer’s evolution slows down.When an excitation reaction is added to the model,the average electron energy,the magnitude of the electric field and the density of electrons decrease,and the evolution of the streamer slows down.An increase in average electron energy will lead to an increase in electric field strength and electron density,and the development of the streamer will be faster.

Bimetallic NiCo boride nanoparticles confined in a MXene network enable efficient ambient ammonia electrosynthesis

Ambient electrocatalytic nitrogen fixation is an emerging technology for green ammonia synthesis,but the absence of optimized,stable and performant catalysts can render its practical application challenging.Herein,bimetallic NiCo boride nanoparticles confined in MXene are shown to accomplish highperformance nitrogen reduction electrolysis.Ta king advantage of the synergistic effect in specific compositions with unique electronic d and p orbits and typical architecture of rich nanosized particles embedded in the interconnected conductive network,the synthesized MXene@NiCoB composite demonstrates extensive improvements in nitrogen molecule chemisorption,active area exposure and charge transport.As a result,optimal NH3 yield rate of 38.7μg h^(-1) mgcat^(-1).and Faradaic efficiency of 6.92%are acquired in0.1 M Na_(2)SO_(4) electrolyte.Moreover,the great catalytic performance can be almost entirely maintained in the cases of repeatedly-cycled and long-term electrolysis.Theoretical investigations reveal that the nitrogen reduction reaction on MXene@NiCoB catalyst proceeds according to the distal pathway,with a distinctly-reduced energy barrier relative to the Co2B counterpart.This work may inspire a new route towards the rational catalyst design for the nitrogen reduction reaction.

Evolution of microstructure, stress and dislocation of AlN thick film on nanopatterned sapphire substrates by hydride vapor phase epitaxy

A crack-free AlN film with 4.5 μm thickness was grown on a 2-inch hole-type nano-patterned sapphire substrates(NPSSs) by hydride vapor phase epitaxy(HVPE). The coalescence, stress evolution, and dislocation annihilation mechanisms in the AlN layer have been investigated. The large voids located on the pattern region were caused by the undesirable parasitic crystallites grown on the sidewalls of the nano-pattern in the early growth stage. The coalescence of the c-plane AlN was hindered by these three-fold crystallites and the special triangle void appeared. The cross-sectional Raman line scan was used to characterize the change of stress with film thickness, which corresponds to the characteristics of different growth stages of AlN. Threading dislocations(TDs) mainly originate from the boundary between misaligned crystallites and the c-plane AlN and the coalescence of two adjacent c-plane AlN crystals, rather than the interface between sapphire and AlN.

Perilipin2 inhibits the replication of hepatitis B virus deoxyribonucleic acid by regulating autophagy under high-fat conditions

BACKGROUND Chronic hepatitis B virus(HBV)infection is often associated with increased lipid deposition in hepatocytes.However,when combined with non-alcoholic fatty liver disease or hyperlipidemia,it tends to have a lower HBV deoxyribonucleic acid(DNA)load.The relationship between lipid metabolism and HBV DNA replication and its underlying mechanisms are not well understood.AIM To investigate the relationship between lipid metabolism and HBV DNA replication and its underlying mechanisms.METHODS 1603 HBsAg-seropositive patients were included in the study.We first explored the relationship between patients'lipid levels,hepatic steatosis,and HBV DNA load.Also,we constructed an HBV infection combined with a hepatic steatosis cell model in vitro by fatty acid stimulation of HepG2.2.15 cells to validate the effect of lipid metabolism on HBV DNA replication in vitro.By knocking down and overexpressing Plin2,we observed whether Plin2 regulates autophagy and HBV replication.By inhibiting both Plin2 and cellular autophagy under high lipid stimulation,we examined whether the Plin2-autophagy pathway regulates HBV replication.RESULTS The results revealed that serum triglyceride levels,high-density lipoprotein levels,and hepatic steatosis ratio were significantly lower in the HBV-DNA high load group.Logistic regression analysis indicated that hepatic steatosis and serum triglyceride levels were negatively correlated with HBV-DNA load.Stratified analysis by HBeAg showed significant negative correlations between HBV-DNA load and hepatic steatosis ratio in both HBeAgpositive and HBeAg-negative groups.An in vitro cell model was developed by stimulating HepG2.2.15 cells with palmitic acid and oleic acid to study the relationship between HBV-DNA load and lipid metabolism.The results of the in vitro experiments suggested that fatty acid treatment increased lipid droplet deposition and decreased the expression of cell supernatant HBsAg,HBeAg,and HBV DNA load.Western blot and polymerase chain reaction analysis showed that fatty acid stimulation significantly induced Plin2 protein expression and inhibited the expression of hepatocyte autophagy proteins.Inhibition of Plin2 protein expression under fatty acid stimulation reversed the reduction in HBsAg and HBeAg expression and HBV DNA load induced by fatty acid stimulation and the inhibition of cellular autophagy.Knocking down Plin2 and blocking autophagy with 3-methyladenine(3-MA)inhibited HBV DNA replication.CONCLUSION In conclusion,lipid metabolism is a significant factor affecting HBV load in patients with HBV infection.The in vitro experiments established that fatty acid stimulation inhibits HBV replication via the Plin2-autophagy pathway.

Effect of preoperative nutrition therapy type and duration on short-time outcomes in gastric cancer patient with gastric outlet obstruction

Objective:To avoid perioperative complications caused malnutrition,nutrition therapy is necessary in gastric outlet obstruction(GOO)patients.Compared to parenteral nutrition(PN),enteral nutrition(EN)is associated with many advantages.This study aimed to investigate whether preoperative EN has beneficial clinical effects compared to preoperative PN in gastric cancer patients with GOO undergoing surgery.Methods:According to the methods of preoperative nutrition therapy,143 patients were divided into EN group(n=42)and PN group(n=101)between January 2013 and December 2017 at the Chinese People’s Liberation Army General Hospital.Multiple logistic regression models were used to assess the association between the methods of preoperative nutrition therapy and postoperative day of flatus passage.The generalized additive model and twopiecewise linear regression model were used to calculate the inflection point of the preoperative nutritional therapy time on the postoperative day of flatus passage in the PN group.Results:EN shortened the postoperative day of flatus passage in gastric cancer patients with GOO,which is a protective factor,especially in patients who underwent non-radical operations and the postoperative day of flatus passage reduced when the preoperative PN therapy was up to 3 d and a longer PN therapy(>3 d)did not accelerate the postoperative recovery of gastrointestinal functions.Conclusions:Preoperative EN therapy would benefit gastric cancer patients with GOO by accelerating postoperative recovery.For patients with absolute obstruction,no more than 3-day PN therapy is recommended if patients can tolerate general anesthesia and surgery.

Numerical simulations of gas-particle flow behavior created by low-level rotary-winged aircraft flight over particle bed

The aerodynamics of gas-particle suspensions is simulated as an Euler-Euler two-fluid model in a revolving rotor over a particle bed. The interactions of collisions between the blade and particles and particle-particle interactions are modeled using the kinetic theory of granular flow(KTGF). The gas turbulence induced by the rotation of the rotor is modeled using the kg-εg model. The flow field of a revolving rotor is simulated using the multiple reference frame(MRF) method. The distributions of velocities, volume fractions, and gas pressure are predicted while the aircraft hovers at different altitudes.The gas pressure decreases from the hub to the tip of the blade, and it is higher at the pressure side than that at the suction side of the rotor. The turbulent kinetic energy of the gas increases toward the blade tip. The volume fraction of particles decreases as the hovering altitude increases. The simulated pressure coefficient is compared with that in experimental measurements.

Study on the discharge mechanism and EM radiation characteristics of Trichel pulse discharge in air

The Trichel pulse stage is an unstable stage of negative corona discharge that can also involve electromagnetic(EM) radiation signals. In this paper, the discharge mechanism and radiation characteristics of the Trichel pulse are studied in the needle-plate electrode configuration. The Trichel pulse current and its EM radiation signals are measured at different applied voltages.The results show that Trichel pulse discharge changes from the random pulse stage to the continuous pulse stage as the applied voltage increases. During these different stages, the normalized shape of the Trichel pulses remains unchanged, while the frequency of the EM radiation generated by the discharge remains unchanged. The discharge mechanism and EM radiation characteristics of the Trichel pulse are theoretically analyzed in the different stages.Both the positive ion sheath and the negative ion cloud play key roles in the formation of the Trichel pulse. The EM radiation signal is generated by the rapidly changing Trichel pulse current, and the Trichel pulse current waveform determines the characteristics of the EM radiation signal.

Analyses on Cancer Incidence and Mortality in Huai’an Area, China, 2010

Objective: The aim of this study was to investigate the cancer incidence and mortality in Huai’an area, China, 2010. Methods: On basis of the criteria of data quality from National Central Cancer Registry (NCCR), data submitted from 8 registries in Huai’an area in 2010 were checked and evaluated. Descriptive analysis included incidence and mortality stratified by areas (urban/rural), sex, age group and cancer sites. Results: The crude incidence rate was 231.17/100,000 (males 276.04/100,000, females 183.87/100,000), age-standardized incidence rate by Chinese standard population (ASIRC) was 179.53/100,000 and by World standard population (ASIRW) was 177.24/ 100,000. The incidence rates increased rapidly in people aged 40 and over, and the peak ages of incidence were at 75 - 79 (males over 85, females at 75 - 79). The cancer mortality rate was 151.26/100,000 (186.06/100,000 in males and 114.58/100,000 in females), age-standardized mortality rate by Chinese standard population (ASMRC) was 116.67/100,000 and by World standard population (ASMRW) was 115.64/100,000. The mortality rates increased rapidly after the age of 50, reaching the peak at the ages over 85 in both males and females. Esophageal, lung, gastric, liver, colorectal, breast, pancreas, lymphoma, brain and central nervous system,?cervical were the most common cancer incident sites. Esophageal, lung, liver, gastric, colorectal, pancreatic, brain and central nervous system, leukemia, breast and lymphoma were the most common cancer sites of death. Conclusions: The data quality of cancer registration is improving. As cancer burden remained high and was different between urban and rural areas, prevention and control should be implemented based on practical situation.

Scheme of long distance power supply for electrified railway traction network based on traction cable

Purpose–The traction cable is paralleled with the existing traction network of electrified railway through transverse connecting line to form the scheme of long distance power supply for the traction network.This paper aims to study the scheme composition and power supply distance(PSD)of the scheme.Design/methodology/approach–Based on the structure of parallel traction network(referred to as“cable traction network(CTN)”),the power supply modes(PSMs)are divided into cableþdirect PSM and cableþautotransformer(AT)PSM(including Japanese mode,French mode and new mode).Taking cableþJapanese AT PSM as an example,the scheme of long distance power supply for CTN under the PSMs of co-phase and out-of-phase power supply are designed.On the basis of establishing the equivalent circuit model and the chain circuit model of CTN,taking the train working voltage as the constraint condition,and based on the power flow calculation of multiple train loads,the calculation formula and process for determining the PSD of CTN are given.The impedance and PSD of CTN under the cableþAT PSM are simulated and analyzed,and a certain line is taken as an example to compare the scheme design.Findings–Results show that the equivalent impedance of CTN under the cableþAT PSM is smaller,and the PSD is about 2.5 times of that under the AT PSM,which can effectively increase the PSD and the flexibility of external power supply location.Originality/value–The research content can effectively improve the PSD of traction power supply system and has important reference value for the engineering application of the scheme.

Particle flux characteristics of a compact high-field cascaded arc plasma device

A new compact cascaded arc device for plasma-wall interaction study is developed at the Institute of Plasma Physics,Chinese Academy of Sciences.A magnetic field up to 0.8 T is achieved to confine plasmas in a 1.2 m long and 0.1 m diameter vacuum chamber.Gas fluid type analysis in this compact vacuum system was done under high particle flux condition.The gas pressure obtained by calculation was consistent with the measurement result.Continuous argon plasma discharge with ion flux of~0.5×10^(24)m^(-2)s^(-1)is successfully sustained for more than 1h.The effects of magnetic field configuration,gas flow rate,and discharge arc current on the ion flux to target were studied in detail.

Analysis of the Agglomeration of Powder in a Coaxial Powder Feeding Nozzle Used for Laser Energy Deposition

To improve the agglomeration of powder in a coaxial powder feeding nozzle used in the frame of a laser energy deposition technique,the influence of several parameters must be carefully assessed.In the present study the problem is addressed by means of numerical simulations based on a DEM-CFD(Discrete Element Method and Discrete Element Method)coupled model.The influence of the powder flow concentration,powder flow focal length and the amount of powder at the nozzle outlet on the rate of convergence of the powder flow is considered.The role played by the nozzle outlet width,the angle between the inner and outer walls and the powder incident angle in determining the powder flow concentration is also considered.The results show that,with increasing of nozzle outlet width,the powder flow concentration per unit volume at the nozzle focal point undergoes a non-monotonic behaviour(it first increases and then decreases).When the nozzle outlet widthδis 1.00 mm,the powder flow concentration at the focal point is maximal and the powder flow convergence can be considered optimal.By increasing the angle between the inner and outer walls,the powder flow concentration related to the upper focus decreases,the focus diameter increases and the powder flow aggregation worsens.The powder flow concentration increases first and then decreases with increasing incident angle.When the incident angleθis 30°,the powder flow exhibits the best agglomeration properties.When the outlet width is smaller,the angle between the inner and outer walls is larger,and when the incident angle is set at 30°,the powder flow concentration of the coaxial nozzle can be effectively improved.

CVD Treatment of Carbon Fibers and Evaluation of Their Dispersion in CFRC

Carbon-fiber-reinforced cement-based (CFRC) composites is a promising functional material which can be used both in the military and civil fields against electromagnetic interference. However, it is essential to make carbon fibers dispersed uniformly during the preparation of CFRC. In this work, short carbon fibers were treated through Chemical Vapor Deposition (CVD) process at high temperature between 900°C and 1200°C under the protection of diluted nitrogen gas N2 to modify the surface of carbon fibers to further strengthen the bonding between carbon fibers and cement matrix. Natural gas (98% CH4) was used as a precursor. It was decomposed to produce an uneven layer of pyrocarbon that was deposited on the surface of carbon fibers. CVD-treated carbon fibers were pre-dispersed by using ultrasonic wave. Both hydroxyethyl cellulose (HEC) and silicon fume were used as dispersants and as admixtures. They helped CVD-treated carbon fibers distribute uniformly. The mass fraction of HEC was around 1.78% in the aqueous solution. Four methods, namely, the simulation experiment (SE) method, the scanning electron microscopy (SEM) method, the fresh mixture (FM) method, and the electrical resistivity measurement (ERM) method were, respectively, applied to evaluate fiber dispersion degree. Each method indicated its own advantages and disadvantages and it therefore catered for different conditions. Of the four evaluation methods, the SE method was the most convenient way to determine the pre-dispersion state prior to the preparation of CFRC composites. This method was helpful for predicting the subsequent dispersion state of carbon fibers in the cement matrix because it economized a large quantity of raw materials and time.

海藻酸钙基凝胶电解质用于纤维超级电容器的连续化制备

溶液挤出法能够连续化制备纤维储能器件,设计与开发高离子电导率的凝胶电解质是实现纤维储能器件一体化挤出的关键.使用海藻酸钙作为聚合物骨架,制备出海藻酸钙/硝酸锂凝胶电解质,其离子电导率高达145.3 mS/cm,并通过溶液挤出法实现了纤维超级电容器的连续制备.基于该凝胶电解质构建的纤维超级电容器,其电压窗口最高可以达到1.8 V,并在0.05~2.00A/g电流密度下均可正常工作.当纤维超级电容器的充放电电流密度由0.05A/g增加到0.50A/g,容量保持率为99.7%.经过1000圈的充放电循环后,纤维超级电容器的容量保持率为99.3%.通过优化凝胶电解质组分、纤维电极直径、凝固浴的浓度和温度,纤维超级电容器的制备速度可以达到20 m/min,最终能够连续构建长度超过3000 m的纤维超级电容器,有望应用于可穿戴电子器件领域.

Stress Concentration Effect in Interface Between Conductor and Epoxy Resin in Coaxial Components of Power Equipment

The spacer used in gas insulated switchgear(GIS)plays a vital role in its safe operation.The mismatch of mechanical properties between conductor and insulating material in spacers results in stress concentration at the interface between them.During a hydrostatic test,mechanical damages are often initiated from the interface.In this paper,the stress between aluminum conductors and epoxy resin is studied by using a simplified coaxial structure specimen.The measurement system and finite element simulation are used to explore the generation of stress and strain during curing and shrinkage.The real-time measurement of strain at the interface shows that the residual strain in the entire process is primarily generated during the cooling stage.Consequently,the temperature and stress/strain distribution at the interface during the cooling stage are further studied,and combined with experiments and simulations.The consistency between the finite element simulation and the experimental measurement results verifies the validity of the simulation method used.The results show that the maximum of the first principal stress generated during the cooling stage of the production process is concentrated on the upper and lower edges of the interface which is critical to the impact of the production quality of the spacer.