Environmentally Friendly and Multifunctional Shaddock Peel-Based Carbon Aerogel for Thermal-Insulation and Microwave Absorption

Eco-friendly electromagnetic wave absorbing materials with excellent thermal infrared stealth property,heat-insulating ability and compression resistance are highly attractive in practical applications.Meeting the aforesaid requirements simultaneously is a formidable challenge.Herein,ultra-light carbon aerogels were fabricated via fresh shaddock peel by facile freeze-drying method and calcination process,forming porous network architecture.With the heating platform temperature of 70℃,the upper surface temperatures of the as-prepared carbon aerogel present a slow upward trend.The color of the sample surface in thermal infrared images is similar to that of the surroundings.With the maximum compressive stress of 2.435 kPa,the carbon aerogels can provide favorable endurance.The shaddock peel-based carbon aerogels possess the minimum reflection loss value(RLmin)of−29.50 dB in X band.Meanwhile,the effective absorption bandwidth covers 5.80 GHz at a relatively thin thickness of only 1.7 mm.With the detection theta of 0°,the maximum radar cross-sectional(RCS)reduction values of 16.28 dB m^(2) can be achieved.Theoretical simulations of RCS have aroused extensive interest owing to their ingenious design and time-saving feature.This work paves the way for preparing multi-functional microwave absorbers derived from biomass raw materials under the guidance of RCS simulations.

Design and performance study of a gas-Cherenkov detector with an off-axis parabolic reflector for inertial confinement fusion experiments

In this work,the gas-Cherenkov detector with an off-axis parabolic reflector(Opr GCD)is designed using the Geant4 Monte Carlo simulation toolkit,which is helpful to improve the collection efficiency of Cherenkov photons.The method to study the performance of Opr GCD based on femtosecond laser-wakefield-accelerated electron beams is presented.Cherenkov signals with high signal-to-noise ratio were obtained,and the measured Cherenkov signals changing with the CO2 pressure were consistent well with the simulation results.The design and study of this Opr GCD system lay the foundation for the application of fusion gamma diagnostics system in large laser facilities of China.

First polar direct-drive exploding-pusher target experiments on the ShenGuang laser facility

Low density and low convergence implosion occurs in the exploding-pusher target experiment, and generates neutrons isotropically to develop a high yield platform.In order to validate the performance of ShenGuang(SG) laser facility and test nuclear diagnostics, all 48-beam lasers with an on-target energy of 48 kJ were firstly used to drive room-temperature, DT gas-filled glass targets.The optimization has been carried out and optimal drive uniformity was obtained by the combination of beam repointing and target.The final irradiation uniformity of less than 5% on polar direct-drive capsules of 540 μm in diameter was achieved, and the highest thermonuclear yield of the polar direct-drive DT fuel implosion at the SG was 1.04 × 10^(13).The experiment results show neutron yields severely depend on the irradiation uniformity and laser timing,and decrease with the increase of the diameter and fuel pressure of the target.The thin CH ablator does not impact the implosion performance, but the laser drive uniformity is important.The simulated results validate that the cos γ distribution laser design is reasonable and can achieve a symmetric pressure distribution.Further optimization will focus on measuring the symmetry of the hot spot by self-emission imaging, increasing the diameter, and decreasing the fuel pressure.

神东矿区水资源承载力研究进展

本文首先对国外水承载力的研究进行了综述,其次对我国水资源开发的规模和区域的人口容量的关系、水资源支持社会经济系统持续发展能力、水资源承载力的评价和预测体系三个方面进行了综述。发现(1)静态评价较多,动态评价较少。(2)在应用中需进一步拓宽和深化利用多目标函数优化评价水资源优化配置的研究。(3)前人研究主要针对国家或省市(区)层面的水资源承载力研究,具体到煤炭矿区尤其是神东矿区的类似个体研究很少。

Light-induced magnetic phase transition in van der Waals antiferromagnets

Control over magnetic properties by optical stimulation is not only interesting from the physics point of view,but also important for practical applications such as magneto-optical devices.Here,based on a simple tight-binding(TB)model,we propose a general theory of light-induced magnetic phase transition(MPT)in antiferromagnets.Considering the fact that the bandgap of the antiferromagnetic(AFM)phase is usually larger than that of the ferromagnetic(FM)one for a given system,we suggest that light-induced electronic excitation prefers to stabilize the FM state over the AFM one,and will induce an MPT from AFM phase to FM phase once a critical photocarrier concentration(αc)is reached.This theory has been confirmed by performing firstprinciples calculations on a series of 2D van der Waals(vd W)antiferromagnets.Interestingly,a linear relationship betweenαc and the intrinsic material parameters is obtained,in agreement with our TB model analysis.Our general theory paves a new way to manipulate 2D magnetism with high speed and superior resolution.

Pavement crack image acquisition methods and crack extraction algorithms:A review

The extraction of pavement cracks is always a hard task in image processing.In airport and road construction,cracking is the main factor for pavement damage,which can decrease the quality of pavement and affect transportation seriously.Cracks also exist in other artificial or natural objects,such as buildings,bridges,tunnels,etc.Among all the object images,pavement crack images are the most complex,so the image processing and analysis for them is harder than other crack images.From the early image acquisition based on photography technology to the current 3 D laser scanning technology,the pavement crack image acquisition technology is becoming more convenient and efficient,but there are still challenges in the automatic processing and recognition of cracks in images.From the early global thresholding to deep learning algorithms,the research for crack extraction has been developed for about 40 years.There are many methods and algorithms that are satisfactory in pavement crack applications,but there is no standard until today.Therefore,in order to know the developing history and the advanced research,we have collected a number of literature in this research topic for summarizing the research artwork status,and giving a review of the pavement crack image acquisition methods and2 D crack extraction algorithms.Also,for image acquisition methods and pavement crack image segmentation,more detailed comparison and discussions are made.

The point defect and electronic structure of K doped LaCo_(0.9)Fe_(0.1)O_(3)perovskite with enhanced microwave absorbing ability

ABO_(3)perovskites,owning unique properties,have great research prospect in electromagnetic wave absorption field.Normally,doping can significantly regulate the dielectric loss,whereas the magnetic loss can be ignored.In this work,the crystal structure and electromagnetic properties can be regulated systematically by the K,Fe co-doping for LaCoO_(3)perovskites(LKCFO)under the condition of fixed F content.In addition,the obtained samples show the obvious interfacial polarization effect on accounting to the small size effect,which is conducive to the effective microwave absorption.By analyzing the evolution of the positron annihilation lifetime and the first-principles calculation of the oxygen density of states for the series of LKCFO perovskites,it is found that the charge transport characteristics will be controlled by the point defect generated by allelic doping.The point defect content decreases and then increases as the doping level rises.The prepared perovskite exhibits the lowest defect density and the largest dielectric loss capability,which indicates that the lower point defects promote electron migration and thus enhance the dielectric loss;thus,the electromagnetic wave absorption bandwidth up to 6.2 GHz is reached.In contrast,both insufficient and excessive K doping are detrimental to the enhancement of microwave absorption.Especially,the practical application value was investigated using Computer Simulation Technology(CST)simulations.The LKCFO-2 exhibits the smallest RCS value(below-10 dBm^(2))at almost-90°-90°with a thickness of 2 mm,providing an effective method for study excellent microwave absorption and scattering property.

Improved electromagnetic dissipation of Fe doping LaCoO_(3)toward broadband microwave absorption

Perovskite LaCoO_(3)is of great potential in electromagnetic wave absorption considering its outstanding dielectric loss as well as the existing magnetic response with the magnetic doping.However,the dissipation mechanism of the magnetic doping on the microwave absorption is lack of sufficient investigated.In this paper,LaCo_(1-x)Fe_(x)O_(3)(x=0,0.05,0.1,0.15,0.2,0.25,0.3,LCFOs)perovskites with different Fe doping amounts were prepared successfully by the sol-gel method and subsequent heat treatment in the air atmosphere.The structure characterization carried out by the frst-principles calculations shows the effect of Fe doping on the dielectric and magnetic properties of LCFOs and the strong hybridization of Co/Fe-3d with O-2p in the LCFOs system was successfully demonstrated.Particularly,when x=0.1 and the thickness is only 1.95 mm,the LaCo_(0.9)Fe_(0.1)O_(3)exhibits the best microwave absorption performance with the minimum reflection loss(RL)value of about-41 dB.The typical samples achieve a broad effective absorption bandwidth(EAB)of 5.16 GHz(7.92-13.08 GHz),which covers the total X band(8-12 GHz).Considering that,the especial Fe doping perovskite is promising to be a candidate as efficient microwave absorbers.

Optimization and modeling of coagulation-flocculation to remove algae and organic matter from surface water by response surface methodology

Seasonal algal blooms of Lake Yangcheng highlight the necessity to develop an effective and optimal water treatment process to enhance the removal of algae and dissolved organic matter (DOM). In the present study, the coagulation performance for the removal of algae, turbidity, dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm (UV254) was investigated systematically by central composite design (CCD) using response surface methodology (RSM). The regression models were developed to illustrate the relationships between coagulation performance and experimental variables. Analysis of variance (ANOVA) was performed to test the significance of the response surface models. It can be concluded that the major mechanisms of coagulation to remove algae and DOM were charge neutralization and sweep flocculation at a pH range of 4.66–6.34. The optimal coagulation conditions with coagulant dosage of 7.57 mg Al/L, pH of 5.42 and initial algal cell density of 3.83 × 106 cell/mL led to removal of 96.76%, 97.64%, 40.23% and 30.12% in term of cell density, turbidity, DOC and UV254 absorbance, respectively, which were in good agreement with the validation experimental results. A comparison between the modeling results derived through both ANOVA and artificial neural networks (ANN) based on experimental data showed a high correlation coefficient, which indicated that the models were significant and fitted well with experimental results. The results proposed a valuable reference for the treatment of algae-laden surface water in practical application by the optimal coagulation-flocculation process.

Critical review of perovskites-based advanced oxidation processes for wastewater treatment: Operational parameters, reaction mechanisms,and prospects

In the field of advanced oxidation processes(AOPs) of wastewater, many materials can be used as heterogeneous catalysts. The role of these catalysts is to activate oxidants and generate reactive oxygen species(ROS) to decompose refractory pollutants. Perovskite oxide, an emerging catalyst in the field of AOPs, has been extensively studied in wastewater treatment. Nevertheless, the application of perovskite in AOP systems still faces some problems, such as leaching of metal ions, a small surface area, a low number of active sites, etc. Herein, this critical review comparatively examines the activation mechanisms of peroxymonosulfate, hydrogen peroxide, and peroxydisulfate. Furthermore, the formation pathways of oxidizing species based on recent advances in experimental and theoretical studies were evaluated. In addition, the impacts of water parameters and constituents such as initial p H, oxidant concentration, catalyst dosage,natural organic matter, halide, phosphate, and carbonate were discussed. Finally, a critical discussion and prospects of mechanism exploration and possible materials development are proposed to confront the existing challenges in the application of perovskite oxides in AOPs.

Carbamazepine degradation by heterogeneous activation of peroxymonosulfate with lanthanum cobaltite perovskite:Performance,mechanism and toxicity

The widely used carbamazepine(CBZ)is one of the most persistent pharmaceuticals and suffers insufficient removal efficiency by conventional wastewater treatment.A synthesized Co-based perovskite(LaCoO3)was used to activate peroxymonosulfate(PMS)in order to degrade CBZ.Results showed that LaCoO3 exhibited an excellent performance in PMS activation and CBZ degradation at neutral pH,with low cobalt leaching.The results of FT-IR and XPS verified the high structurally and chemically stability of LaCoO3 in PMS activation.Electron spin resonance(ESR)analysis suggested the generation of radical species,such as sulfate radicals(SO4·-)and hydroxyl radicals(·OH).Radical quenching experiments further revealed the responsibility of SO4·-as the dominant oxidant for CBZ oxidation.Ten products were detected via the oxidation of CBZ,with the olefinic double bond attacked by SO4·-as the initial step.Hydroxylation,hydrolysis,cyclization and dehydration were involved along the transformation of CBZ.The toxicity of CBZ solution was significantly reduced after treating by PMS/LaCoO3.

Carbon fibers@Co-ZIFs derivations composites as highly efficient electromagnetic wave absorbers

To reduce electromagnetic(EM)wave interference pollution,in this work,carbon fibers@Co-ZIFs derivations(CFZD)as an advanced EM wave absorbing material was successfully prepared.The yolk-shell structure of the magnetic metal particles generated a large amount of contact area,facilitating the interface polarization and relaxation.As a result,the optimized sample delivers a maximum reflection loss(RL)value of-19.2 d B with a bandwidth of 2.6 GHz at a small thickness of 1.3 mm.Additionally,ANSYS Electronics Desktop 2018(HFSS)was used to simulate the radar cross section(RCS)reduction in practical application based on these composites.The RCS values of composite coatings are less than-10 d B m^(2) at the range of-90°<theta<-10°and 10°<theta<90°,which indicate the effective reduction of the radar reflection signal by the composite coatings.The work is of reference significance for preparing great absorbing materials and designing absorbing coatings by combining simulation method.

Beam shaping of high power diode laser stack into homogeneous line

In this paper, analysis of beam shaping and homogenization of high power diode laser stack into a line focus with dimension of 10 mm x 0.5 mm was reported. The beam shaping and homogenization was simulated by using ZemaX-ray tracing technique. The results have shown that intensity distribution after beam shaping and homogenization at the work piece is a fiat top for the slow axis with homogeneity over 95% and a Gaussian distribution for the fast axis.

Slab Yb：YAG pulse amplifier with high amplification gain and signal-to-noise ratio

This study experimentally investigated a Yb： YAG pulse laser amplifier with a high amplification gain and a high signal-to-noise ratio （SNR）. The highest amplification gain of 172 and highest pulse energy of 131 mJ were obtained with the highest SNR of 24.9 dB from a volume gain of 10 mm × 10 mm × 1 mm. The output beam quality values ofM2 = 1.91 in the slow axis and M2 = 1.58 in the fast axis were also achieved.

Industry Distribution Characteristics of Benzene-Induced Leukemia—7 PLADs,China,2005–2019

Summary What is already known about this topic?In the 1980s.benzene-induced leukemia(BIL)mainly occurred in shoemaking and painting industries.Now the industry distribution of benzene-induced leukemia may have changed over time.What is added by this report?BlL cases mainly occurred in the manufacturing industry from 2005-2019,especially in private enterprises and small/medium-sized enterprises.The industry with the largest number of new cases of BIL was the general and special equipment manufacturing.The number of leukemia cases in emerging industries such as computer/electronic product manufacturing was found to be increasing.What are the implications for public health practice?Strengthening supervision and regulation of manufacturing,especially of small/medium-sized enterprises and emerging manufacturing industry,may be effective in reducing BIL.