Dynamic adaptive spatio-temporal graph network for COVID-19 forecasting

Appropriately characterising the mixed space-time relations of the contagion process caused by hybrid space and time factors remains the primary challenge in COVID-19 forecasting.However,in previous deep learning models for epidemic forecasting,spatial and temporal variations are captured separately.A unified model is developed to cover all spatio-temporal relations.However,this measure is insufficient for modelling the complex spatio-temporal relations of infectious disease transmission.A dynamic adaptive spatio-temporal graph network(DASTGN)is proposed based on attention mechanisms to improve prediction accuracy.In DASTGN,complex spatio-temporal relations are depicted by adaptively fusing the mixed space-time effects and dynamic space-time dependency structure.This dual-scale model considers the time-specific,space-specific,and direct effects of the propagation process at the fine-grained level.Furthermore,the model characterises impacts from various space-time neighbour blocks under time-varying interventions at the coarse-grained level.The performance comparisons on the three COVID-19 datasets reveal that DASTGN achieves state-of-the-art results with a maximum improvement of 17.092%in the root mean-square error and 11.563%in the mean absolute error.Experimental results indicate that the mechanisms of designing DASTGN can effectively detect some spreading characteristics of COVID-19.The spatio-temporal weight matrices learned in each proposed module reveal diffusion patterns in various scenarios.In conclusion,DASTGN has successfully captured the dynamic spatio-temporal variations of COVID-19,and considering multiple dynamic space-time relationships is essential in epidemic forecasting.

Resistance characteristics of paste pipeline flow in a pulse-pumping environment

Paste flow patterns and microscopic particle structures were studied in a pressurized environment generated by a pulse pump.Complex loop-pipe experiments and fluid-solid coupling-based simulations were conducted.The scanning electron microscopy technique was also applied.Results revealed that flow resistance is closely related to pipeline curvature and angle in a complex pipe network.The vertical downward-straight pipe-inclined downward combination was adopted to effectively reduce the loss in resistance along with reducing the number of bends or increasing the radius of bend curvature.The maximum velocity ratio and velocity offset values could quantitatively characterize the influences of different pipeline layouts on the resistance.The correlation reached 96%.Particle distribution and interparticle forces affected flow resistance.Uniform particle states and weak interparticle forces were conducive to steady transport.Pulse pump pressure led to high flow resistance.It could improve pipe flow stability by increasing flow uniformity and particle motion stability.These results can contribute to safe and efficient paste filling.

Involvement of lncRNAs in the tumor microenvironment:a new property of tumor immunity

Immune checkpoint blockade(ICB)has achieved durable clinical responses and has significantly improved the overall survival of cancer patients1.Among the ICB agents,programmed death 1(PD-1)/programmed death ligand 1(PD-L1)antibodies are used to treat various human tumors by blocking PD-1/PD-L1 signaling.Impressive response rates with low autoimmune toxicity have been reported in 20%–30%of non-selected patients1;however,most patients fail to respond to PD-1/PD-L1 blockade or acquire resistance during therapy through unknown mechanisms1.

Thermal characterization of GaN heteroepitaxies using ultraviolet transient thermoreflectance

Thermal transport properties of GaN heteroepitaxial structures are of critical importance for the thermal management of high-power GaN electronic and optoelectronic devices. Ultraviolet(UV) lasers are employed to directly heat and sense the GaN epilayers in the transient thermoreflectance(TTR) measurement, obtaining important thermal transport properties in different GaN heterostructures, which include a diamond thin film heat spreader grown on GaN. The UV TTR technique enables rapid and non-contact thermal characterization for GaN wafers.

Theoretical Analysis of Solidly Mounted Film Bulk Acoustic Resonator with Nanocrystalline Diamond as High Impedance Material of Bragg Reflector

In this paper,a solidly mounted resonator(SMR)was designed with nanocrystalline diamond(NCD)as the high acoustic impedance material of Bragg reflector to improve the quality.We used Mathcad to investigate the effect of the Bragg reflector on the performance of the SMR,as well as the influence of different materials and the number of layers of Bragg reflector on the quality factor Q.Results show that the Bragg reflector could reduce energy loss effectively,and the higher the impedance of the high acoustic impedance layer,the better the SMR.The parasitic factors of the SMR using two high acoustic impedance materials,tungsten(W)and NCD,were also simulated by an Advanced Design System(ADS)using the Mason model.It was found that the parasitic effect caused by metal would significantly decrease the Q factor of the SMR.In the frequency range below 6 GHz,within which the SMR works normally,NCD performed better than W.Therefore,NCD is a better choice of high acoustic impedance material in the design of the SMR,with improved quality at high frequency and low loss.The optimum number of layers of Bragg reflector is 6.

Research of Enterprise Storage Ecosystem Based on Storage Theory and Nonlinear Discrete Optimization

Warehousing and transferring strategies are an important part of business operations. The issue of optimal warehousing and transferring strategy is studied in this paper. Wal-Mart in Wuhan serves as an example to establish a (s, S) random storage strategy model, a Markov chain model, and a nonlinear discrete programming model, aiming at maximizing the profit per cycle of every branch and further maximizing the company’s total profit per cycle. Among them, the random storage strategy model establishes a security zone of inventory for every branch, that is, it can meet consumers’ demand without spending too much storage costs. The Markov chain model is used to get the probability of losing sales opportunities in every branch. The nonlinear discrete programming model takes into account the horizontal transferring among branches, which further maximizes the company’s overall profit expectations. The three models above can be used to formulate inventory strategies, assess risks, and provide advice for every branch in order to form a complete storage ecosystem and provide constructive suggestions for the company’s operations.

Work Function Optimization Technology of Indium Tin Oxide Films

Indium tin oxide(In_(2)O_(3)∶Sn)film is one of the most potential materials in the field of semiconductor industry.However,untreated In2O3∶Sn film has a low work function which can result in a high energy barrier that hinders the passage of carriers through the interface,thus leading to poor overall performance of directly prepared devices.In this study,crystalline transparent conductive In_(2)O_(3)∶Sn films were prepared by plasma exposure assisted magnetron sputtering under room temperature.Based on multiple testing methods,it can be found that the low temperature crystallization characteristics of In_(2)O_(3)∶Sn film were enhanced and the work function was effectively improved after Ar^(+)plasma exposure.The increase of the work function of In_(2)O_(3)∶Sn film was due to the increment of Sn⁃O bond on the surface brought by the transition from low oxidation state Sn^(2+)to high oxidation state Sn^(4+)under the action of high exposure.

具有超低开关电场的可控的易失性至非易失性单晶无铅双钙钛矿忆阻器

全无机无铅双钙钛矿由于其优异的电子传输能力、高光敏性、低毒性和环境稳定性,为电子/光电存储器件提供了潜在的材料.然而,钙钛矿薄膜的多晶性质严重限制了器件性能.在此,我们展示了一种基于单晶双钙钛矿Cs_(2)AgBiBr_(6)的高性能忆阻器,其具有6.67×10^(4)V m^(-1)的超低开关电场和10^(7)的高电流开/关比.值得注意的是,Cs_(2)AgBiBr_(6)的电阻开关行为与单晶钙钛矿的厚度相关,当单晶厚度从100到800 nm变化时,忆阻器从易失性的阈值开关行为演变为非易失性的忆阻开关行为.元素分析表明,Cs_(2)AgBiBr_(6)中导电通道的形成与具有低活化能Br空位的迁移有关.此外,形成的导电通道可以被具有不同波长和强度的光照湮灭,从而实现具有单独的电写入和光擦除的光电存储器.我们的研究结果为单晶钙钛矿中的离子迁移提供了深刻的见解,并为其在未来的电子和光电存储器中的应用提供了理论基础.

基于亚纳米孔道微调制备用于高效分子筛分的超薄耐酸膜

分离膜被广泛应用于分子分离等领域,但由于膜本身通量与筛分性能之间此消彼长的“trade-off”效应,传统分离膜的效率受到极大限制.本文报道了以多酚作为限速的亲核试剂,与二异氰酸酯进行界面缩合,制备得到了孔径均匀且选择层厚度仅为10 nm的超薄聚氨酯复合膜,并通过实验和密度泛函理论(DFT)模拟计算进行了验证.制备的新型聚氨酯复合纳滤膜在通量提高的同时显著增强了对各种染料和重金属离子的筛分性能,成功突破了传统聚合物分离膜的“trade-off”瓶颈问题.此外合成聚氨酯复合膜的高度交联结构使其能够在强酸条件下稳定运行500 h以上,在环境修复和资源回收利用等领域具有巨大的应用潜力.

Far-infrared transparent conductors

The long-standing challenge in designing far-infrared transparent conductors(FIRTC)is the combination of high plasma absorption edge(λ_(p))and high conductivity(σ).These competing requirements are commonly met by tuning carrier concentration or/and effective carrier mass in a metal oxide/oxonate with low optical dielectric constant(ε_(opt)=2-7).However,despite the highσ,the transparent band is limited to mid-infrared(λ_(p)<5μm).In this paper,we break the trade-off between highσandλ_(p)by increasing the“so-called constant”ε_(opt)that has been neglected,and successfully develop the material family of FIRTC withε_(opt)>15 andλ_(p)>15μm.These FIRTC crystals are mainly octahedrally-coordinated heavy-metal chalcogenides and their solid solutions with shallow-level defects.Their highε_(opt)relies on the formation of electron-deficiency multicenter bonds resulting in the great electron-polarization effect.The new FIRTC enables us to develop the first“continuous film”type far-infrared electromagnetic shielder that is unattainable using traditional materials.Therefore,this study may inaugurate a new era in far-infrared optoelectronics.

Design strategy of a high-performance multispectral stealth material based on the 3D meta-atom

In this paper,a 3D meta-atom-based structure is constructed for the multifunctional compatible design of visible,infrared,and microwave.To achieve high performance,a novel dispersion tailoring strategy is proposed.Through the incorporation of multiple controllable losses within the 3D meta-atom,the dispersion characteristics are tailored to the desired target region.The effectiveness of the strategy is verified with an error rate of less than5%.A proof-of-concept prototype is designed and fabricated,exhibiting high visible transparency,low infrared emission of 0.28,and microwave ultra-broadband absorption with a fractional bandwidth of 150%under 2.7 to18.7 GHz.This work contributes a novel design strategy for the development of high-performance multispectral stealth materials with wide applications.

Advanced liquid crystal-based switchable optical devices for light protection applications:principles and strategies

With the development of optical technologies,transparent materials that provide protection from light have received considerable attention from scholars.As important channels for external light,windows play a vital role in the regulation of light in buildings,vehicles,and aircrafts.There is a need for windows with switchable optical properties to prevent or attenuate damage or interference to the human eye and light-sensitive instruments by inappropriate optical radiation.In this context,liquid crystals(LCs),owing to their rich responsiveness and unique optical properties,have been considered among the best candidates for advanced light protection materials.In this review,we provide an overview of advances in research on LC-based methods for protection against light.First,we introduce the characteristics of different light sources and their protection requirements.Second,we introduce several classes of light modulation principles based on liquid crystal materials and demonstrate the feasibility of using them for light protection.In addition,we discuss current light protection strategies based on liquid crystal materials for different applications.Finally,we discuss the problems and shortcomings of current strategies.We propose several suggestions for the development of liquid crystal materials in the field of light protection.

Nanodiamond reinforced self-healing and transparent poly(urethane-urea)protective coating for scratch resistance

With increasing demand for scratch-resistant flexible electro-nics,the development of transparent coatings with good scratch resistance and self-healing properties has emerged as a key research topic.In this study,a high-strength self-healing poly(urethane-urea)(PUU)-based nanocomposite coating was prepared by introducing functionalized nanodiamond(ND)into a PUU matrix via solution blending.The PUU matrix had hard-segment repeating units and was constructed using iso-phorone diamine and isophorone isocyanate.The ND particles were modifed using a silane coupling agent,3-aminopropyl-triethoxysilane,to obtain well-dispersed KH-ND nanoparticles.KH-ND promoted microphase separation in the PU matrix,inducing the formation of dense and homogeneous hard domains that dissipated stress,prevented further crack devel-opment,and improved the mechanical properties and scratch resistance of the coating.In addition,the coating exhibited excellent self-healing properties.Fourier-transform infrared spectroscopy,scanning electron microscopy,and atomic force microscopy were used to characterize the self-healing and hardening mechanisms of the coating.The environmentally friendly PUU/KH-ND coating is easy to prepare and has broad application prospects in transparent and anti-scratch coatings for flexible electronics,automobiles,and home appliances.

基于语义三角形的自然人机交互模型

随着认知科学与移动计算技术的发展与应用,如何构建与评估自然用户界面成为越来越重要的问题.为此,本文在分析了自然人机交互主要特征的基础上,指出了自然语言的使用及其语义理解的重要性,借用语言学的语义三角形模型,提出了基于语义三角形的自然人机交互模型.该模型诠释了自然人机交互场景下,人与计算机之间信息流转与理解过程.最后,基于该模型给出了自然性、连续性和易学性3个评估要素的评估思路.

Research on the Integrated Teaching Design of Junior High School English Units Based on the Key Competencies of English Subjects

The overall teaching design for the junior middle school English unit aims to maximize the use of teaching resources by using the unit as the central theme,integrating it throughout all sections and related activities.This approach continually reinforces students’understanding and retention of individual lesson content while fostering their core literacy and skills.It promotes a comprehensive development of students’listening,speaking,reading,and writing skills,allowing them to engage repeatedly with the language materials until they internalize them as part of their language proficiency.

碎片对铝合金薄板抗侵彻性能影响数值仿真研究

弹体在撞击多层板的过程中会产生离散碎片,离散碎片可能对靶板的抗撞击性能产生影响.通过改变弹体与碎片之间的相对撞击位置,揭示撞击过程中碎片与弹体接触方式对靶板抗撞击特性的影响规律及机理.利用ABAQUS有限元软件,采用合适材料参数及准则,建立平头弹及碎片撞击2A12-T4铝合金靶板的数值仿真模型,弹体与碎片采用四种不同面积接触方式.基于弹体高速撞击铝合金单层板实验结果,验证数值仿真模型及参数的有效性.通过数值仿真计算结果,建立了弹体撞击靶体速度曲线,获取了不同初始撞击条件下靶板的弹道极限速度,分析了弹体对靶体的撞击物理过程及失效机制.基于数值仿真计算结果可以发现,靶体对碎片抗侵彻性能受弹体速度以及弹体与碎片之间的相互位置等因素共同作用,靶体的弹道极限速度随弹体与碎片接触面积的增加先增加后减小.对于靶体的抗撞击性能,弹体与碎片之间接触面积存在一个最佳值,接触面积太大或者太小都会减小靶板的损伤面积,从而减少撞击过程中靶板吸收的能量.

中国农田土壤动物长期监测样地科学调查监测的实施方法

我国农田土壤动物面临严峻的多样性丧失问题,建设监测样地并开展长期监测是解决该问题的重要途径,但至今国内外仍缺乏农田土壤动物长期监测样地科学调查监测的实施方法。依据BCI 50 ha大型固定样地建设规范,参照我国已建成的森林和农田土壤动物大型固定样地监测经验,本文提出了农田土壤动物长期监测样地科学调查监测的实施方法。首先,需要明确科学问题,确定科学调查监测应遵守的基本原则。其次,需要规范长期调查监测涉及的专业术语,依据研究目的和实际情况选择地点和样地,参照建设规范和农田特征建立农田土壤动物大型固定样地。第三,以研究农田土壤动物多样性为核心,揭示土壤动物在农田生态系统健康和功能中的作用,有选择性地开展4类27项科学指标的长期监测工作,要求按照统一的、规范化的工作流程开展野外调查和室内实验。最后,要科学规范地完成标本的鉴定描述和保存保管,研发体现农田土壤动物特征的数据库和管理信息系统。希望本文的研究结果能推动我国乃至世界范围的规范化样地建设和标准化网络监测,为我国农田土壤动物评估与保护提供长期可靠的数据支撑。

小麦–玉米轮作农田土壤螨多样性空间分布格局

以农田土壤动物长期监测样地为平台,阐明土壤动物物种和功能多样性空间分布格局,是揭示农田土壤动物多样性维持机制、提高农田土壤质量的重要基础。本试验于2020年10月,对河南商丘农田土壤动物大型固定样地(9 ha)的210个采样点进行土壤样品野外采集和室内分离,将土壤螨样品鉴定到种并测量其体长体宽数据,以说明小麦–玉米轮作农田土壤螨多样性及其体长体宽的空间分布格局。结果表明:(1)共捕获成螨个体17,256头,其中甲螨亚目为优势类群,其个体数占总捕获量的94.67%;MGP分析表明样地甲螨群落属于P型,说明受人为因素影响强烈;生态位宽度和重叠度分析表明,进化程度越高甲螨的生态位宽度越宽,进化程度越相近甲螨之间的竞争越激烈。(2)Moran’s I分析显示,在20–100 m的空间尺度上,土壤螨群落、优势种的个体数和体长体宽多为显著正相关;在220–300 m的空间尺度上,部分为显著负的空间自相关。半方差函数结果表明,甲螨群落物种数、个体数和体长体宽的空间变异主要受确定性过程影响,中气门螨群落的空间变异由确定性和随机性过程共同影响。(3)土壤螨个体数与体长体宽存在显著弱的负相关关系,这种关系普遍存在于土壤螨各群落与优势种中。本研究建议同时开展物种多样性和以体长体宽为代表的功能多样性空间格局研究,对揭示土壤螨群落维持机制、保护土壤螨多样性具有重要意义。

Au nanospheres modified boron-doped diamond microelectrode grown via hydrogen plasma etching solid doping source for dopamine detection

Boron doped diamond(BDD)electrode is a promising electrochemical material for detecting dopamine level in the human’s body.In this work,we developed a new doping source-graphite and solid boron oxide powders to synthesize BDD film with microwave plasma chemical vapor deposition,so as to avoid using toxic or corrosive dopants,such as boroethane and trimethylborate.The synthesized BDD film is pinhole free and with high doping density of 8.44×10^20 cm^-3 calculated from the Raman spectroscopy.Subsequently,Au nanospheres were decorated on the surface of BDD film to improve electrochemical performance of the BDD film.The Au nanoparticles modified BDD electrode demonstrates an excellent electrochemical response,a high sensitivity(in the range of 5μM-1 m M),and a low detection limit(~0.8μM)for detecting dopamine.

Evolution of microstructures and optical properties of gadolinium oxide with oxygen flow rate and annealing temperature

In this study, the effects of oxygen flow rate and annealing temperature on Gd_2 O_3 structures and optical properties were systematically analyzed. Gd_2 O_3 films were deposited on both quartz and ZnS substrates by magnetron sputtering and then annealed under vacuum at 700, 800 and 900℃, Restructure and phase transformation from cubic to monoclinic occur at different temperatures depending on the oxygen flow rate. The optical band gap, which is more sensitive to the annealing temperature than oxygen flow rate changes from 5.32 to 5.65 eV. The refractive index is approximately 1.75 at 550 nm and is adjustable by the oxygen flow rate. The transmittance of the ZnS substrate with Gd_2 O_3 film exceeds 80% and reaches82% at the 7.5-9.5 μm range. When ZnS is coated on both sides, the transmittance is increased to approximately 90%. Our results indicate that Gd_2 O_3 films are promising new candidates for anti-reflective coatings in the infrared region.