Hollow Gradient-Structured Iron-Anchored Carbon Nanospheres for Enhanced Electromagnetic Wave Absorption

In the present paper,a microwave absorber with nanoscale gradient structure was proposed for enhancing the electromagnetic absorption performance.The inorganic-organic competitive coating strategy was employed,which can effectively adjust the thermodynamic and kinetic reactions of iron ions during the solvothermal process.As a result,Fe nanoparticles can be gradually decreased from the inner side to the surface across the hollow carbon shell.The results reveal that it offers an outstanding reflection loss value in combination with broadband wave absorption and flexible adjustment ability,which is superior to other relative graded distribution structures and satisfied with the requirements of lightweight equipment.In addition,this work elucidates the intrinsic microwave regulation mechanism of the multiscale hybrid electromagnetic wave absorber.The excellent impedance matching and moderate dielectric parameters are exhibited to be the dominative factors for the promotion of microwave absorption performance of the optimized materials.This strategy to prepare gradient-distributed microwave absorbing materials initiates a new way for designing and fabricating wave absorber with excellent impedance matching property in practical applications.

China requires region-specific manure treatment and recycling technologies

Heterogenous distribution of crops,feed and livestock across China has halted the circulation of nutrients within the agricultural system and is responsible for massive nutrient losses[1,2].Generated livestock manure exceeded optimal crop requirements in 30%and 50%of over 2300 studied counties when there was improved recycling of nitrogen(N)and phosphorus(P)in the food chain,repectively[2].Most of these counties are located in southern and coastal areas,whereas there is a deficit of livestock manure in northern and western China.Such heterogenous distribution of crop-livestock production led to 4.0 Tg manure N and 0.9 Tg manure P[2],which are economically impossible to recycle and will end up in the surrounding environment.In addition,about 40%of feed protein consumed by domestic livestock production relied on importation,putting China’s livestock production supply at high risk in the post pandemic world[3].Hence,China is facing the twin issues of too many manure nutrients but too little feed nutrients simultaneously.

Analyzing the Operational Performance Migration of Telecom Operators

Due to the rapid development of mobile Internet services, such as Skype and WeChat, traditional telecom services have suffered a large decline in the business volumes in recent years. Thus, telecom operators pay much attention to analyzing the changes of the enterprise performance, in order to adjust market strategies in time. In this paper, we propose a new methodology to analyze the operation data of telecom operators dynamically,which can characterize the changing process of the operating states and predict the developing trends. In particular, the proposed methodology contains two steps: migration pattern analysis and trajectory pattern analysis.Firstly, migration analysis is based on the changing of operating states between two points-in-time, which is referred to as the migration paths. Applying the clustering analysis to the migration paths can obtain the migration patterns, which characterize the changing feature of telecom operators during a short period, e.g. one month. Secondly, we combine a sequence of consecutive migration paths to obtain the migration trajectory. Through analyzing different trajectories based on the hierarchical cluster method and the Markov chain model, we obtain the trajectory patterns,which describe the changing progress during a relatively long period, e.g. one year. Based on the trajectory patterns, we can predict the possible performance changes. Finally, we apply the proposed method to a Chinese telecom operator for an empirical research, and has obtained a lot of development rules which provides insights into current telecom.

General Situations of Development of Photovoltaic Agriculture

This paper firstly introduced policy of photovoltaic agriculture in China. It discussed significance of developing photovoltaic agriculture. Then,it introduced progress in application of photovoltaic agriculture at both home and abroad. Finally,it pointed out existing problems in photovoltaic agriculture and came up with recommendations for development of photovoltaic agriculture in China.

德国电子监控制度述评——以巴登-符腾堡州为例

在德国的司法实务中,电子监控的适用范围极其有限,引发这种现象的原因既与电子监控本身的特性有关,也与德国的司法文化和社会舆论有关。第一,在德国目前的量刑实践中出现了简化量刑的趋势,法官主要考虑犯罪行为的严重性,而刑罚的一般预防和特别预防功能则逐渐被边缘化;第二,虽然实证研究的结论并未与预期相悖,但仅仅作为一种简单监控手段的电子监控无法被德国的刑事政策所接受;第三,由于涉及复杂的专业知识和严格的数据信息保护规则,法官在量刑时更倾向于以传统的监督方式替代电子监控;第四,公众对电子监控及司法私有化的抵触心理进一步降低了电子监控在德国广泛实施的可能性。

Causal analysis of competing atomistic mechanisms in ferroelectric materials from high-resolution scanning transmission electron microscopy data

Machine learning has emerged as a powerful tool for the analysis of mesoscopic and atomically resolved images and spectroscopy in electron and scanning probe microscopy,with the applications ranging from feature extraction to information compression and elucidation of relevant order parameters to inversion of imaging data to reconstruct structural models.However,the fundamental limitation of machine learning methods is their correlative nature,leading to extreme susceptibility to confounding factors.Here,we implement the workflow for causal analysis of structural scanning transmission electron microscopy(STEM)data and explore the interplay between physical and chemical effects in a ferroelectric perovskite across the ferroelectric–antiferroelectric phase transitions.

Deep learning ferroelectric polarization distributions from STEM data via with and without atom finding

Over the last decade,scanning transmission electron microscopy(STEM)has emerged as a powerful tool for probing atomic structures of complex materials with picometer precision,opening the pathway toward exploring ferroelectric,ferroelastic,and chemical phenomena on the atomic scale.Analyses to date extracting a polarization signal from lattice coupled distortions in STEM imaging rely on discovery of atomic positions from intensity maxima/minima and subsequent calculation of polarization and other order parameter fields from the atomic displacements.Here,we explore the feasibility of polarization mapping directly from the analysis of STEM images using deep convolutional neural networks(DCNNs).In this approach,the DCNN is trained on the labeled part of the image(i.e.,for human labelling),and the trained network is subsequently applied to other images.We explore the effects of the choice of the descriptors(centered on atomic columns and grid-based),the effects of observational bias,and whether the network trained on one composition can be applied to a different one.This analysis demonstrates the tremendous potential of the DCNN for the analysis of high-resolution STEM imaging and spectral data and highlights the associated limitations.

Self-organization of various“phase-separated”nanostructures in a single chemical vapor deposition

Chemical vapor deposition(CVD)is one of the most versatile techniques for the controlled synthesis of functional nanomaterials.When multiple precursors are induced,the CVD process often gives rise to the growth of doped or alloy compounds.In this work,we demonstrate the self-assembly of a variety of‘phase-separated’functional nanostructures from a single CVD in the presence of various precursors.In specific,with silicon substrate and powder of Mn and SnTe as precursors,we achieved self-organized nanostructures including Si/SiOx core-shell nanowire heterostructures both with and without embedded manganese silicide particles,Mn11Si19 nanowires,and SnTe nanoplates.The Si/SiOx core-shell nanowires embedded with manganese silicide particles were grown along the<111>direction of the crystalline Si via an Au-catalyzed vapor-liquid-solid process,in which the Si and Mn vapors were supplied from the heated silicon substrates and Mn powder,respectively.In contrast,direct vapor-solid deposition led to particle-free<110>-oriented Si/SiOx core-shell nanowires and<100>-oriented Mn11Si19 nanowires,a promising thermoelectric material.No Sn or Te impurities were detected in these nanostructures down to the experimental limit.Topological crystalline insulator SnTe nanoplates with dominant{100}and{111}facets were found to be free of Mn(and Si)impurities,although nanoparticles and nanowires containing Mn were found in the vicinity of the nanoplates.While multiple-channel transport was observed in the SnTe nanoplates,it may not be related to the topological surface states due to surface oxidation.Finally,we carried out thermodynamic analysis and density functional theory calculations to understand the‘phase-separation’phenomenon and further discuss general approaches to grow phase-pure samples when the precursors contain residual impurities.

Design of hollow core step-index antiresonant fiber with stepped refractive indices cladding

With the benefits of low latency,wide transmission bandwidth,and large mode field area,hollow-core antiresonant fiber(HC-ARF)has been a research hotspot in the past decade.In this paper,a hollow core step-index antiresonant fiber(HC-SARF),with stepped refractive indices cladding,is proposed and numerically demonstrated with the benefits of loss reduction and bending improvement.Glass-based capil-laries with both high(n=1.45)and low(as low as n=1.36)refractive indices layers are introduced and formatted in the cladding air holes.Using the finite element method to perform numerical analysis of the designed fiber,results show that at the laser wavelengths of 980 and 1064 nm,the confinement loss is favorably reduced by about 6 dB/km compared with the conventional uniform cladding HC-ARF.The bending loss,around 15 cm bending radius of this fiber,is also reduced by 2 dB/km.The cladding air hole radius in this fiber is further investigated to optimize the confinement loss and the mode field diameter with single-mode transmission behavior.This proposed HC-SARF has great potential in optical fiber transmission and high energy delivery.