氨基甲基吡啶改性氮化硼/线型低密度聚乙烯复合材料的热性能及力学性能

利用4-氨基甲基吡啶与马来酸酐接枝线型低密度聚乙烯(LLDPE-g-MAH)成功制备了氨基甲基吡啶接枝线型低密度聚乙烯(LLDPE-g-Py),然后采用熔融共混法制备了改性的BN/LLDPE(mBN/LLDPE)复合材料。深入研究了mBN/LLDPE复合材料的热性能和力学性能等。结果表明,LLDPE-g-Py的加入,使mBN/LLDPE复合材料的导热性能得到很大提升,但LLDPE-g-Py过多会导致其耐热性降低。为了改善复合材料的耐热性,将LLDPE-g-Py质量分数固定为10%。当BN质量分数为40%时,mBN/LLDPE复合材料的导热系数达到了0.95 W/(m·K),为纯LLDPE导热系数(0.32 W/(m·K))的3倍。同时,mBN/LLDPE复合材料的拉伸强度在小幅度下降的情况下,其断裂伸长率得到明显的改善。

Kinetic mechanism of copper extraction from methylchlorosilane slurry residue using hydrogen peroxide as oxidant

Copper was extracted from methylchlorosilane slurry residue by a direct hydrogen peroxide leaching method.A number of experimental parameters were analyzed to determine the extraction efficiency of copper.The extraction efficiency of copper reached 98.5%under the optimal leaching conditions,such as the hydrogen peroxide concentration of 1.875 mol·L^(-1),the leaching temperature of 323 K,the liquid–solid ratio of 20 ml·g^(-1),and the stirring speed of 300 r·min^(-1).The leaching kinetics of the copper extraction process was then described by the shrinking core model.There were two stages.The first stage was controlled by chemical reactions,while the second stage was controlled by interface transfer and product layer diffusion.The activation energy and kinetic control equations were determined,as well as an explanation of the leaching mechanism of copper extraction based on kinetic analysis and materials characterization.Copper resources can be recovered from the methylchlorosilane slurry residue efficiently and inexpensively with the methods used in this study.

Current advances of biocontainment strategy in synthetic biology

Synthetic biotechnology has led to the widespread application of genetically modified organisms(GMOs)in biochemistry, bioenergy, and therapy. However, the uncontrolled spread of GMOs may lead to genetic contamination by horizontal gene transfer, resulting in unpredictable biosafety risks. To deal with these challenges, many effective methods have been developed for biocontainment. In this article, we summarize and discuss recent advances in biocontainment strategies from three aspects: DNA replication, transcriptional regulation, and protein translation. We also briefly introduce the efforts in the biocontainment convention, such as the recent publication of the Tianjin Biosecurity Guidelines for the Code of Conduct for Scientists.

Effects of laser energy on the surface quality and properties of electrodeposited zinc-nickel-molybdenum coatings

As a substitute for toxic cadmium coatings in the aerospace industry,zinc-nickel coatings have excellent application prospects,and their properties can be improved by adding molybdenum.In this study,laser-assisted electrodeposition is used to improve the surface quality and properties of Zn–Ni–Mo coatings,with investigation of how laser energy in the range of 0–21.1μJ affects their element content,surface morphology,crystal phase,microhardness,residual internal stress,and corrosion resistance.The laser irradiation accelerates the electrodeposition,refines the grain size,improves the hydrogen adsorption,and reduces the residual tensile stress,and a laser energy of 15.4μJ gives the highest Ni and Mo contents and the lowest Zn content,as well as the optimum surface morphology,microhardness,residual internal stress,and corrosion resistance of the coating.

Delay-Optimal Random Access in Large-Scale Energy Harvesting IoT Networks Based on Mean Field Game

With energy harvesting capability, the Internet of things(IoT) devices transmit data depending on their available energy, which leads to a more complicated coupling and brings new technical challenges to delay optimization. In this paper,we study the delay-optimal random access(RA) in large-scale energy harvesting IoT networks. We model a two-dimensional Markov decision process(MDP)to address the coupling between the data and energy queues, and adopt the mean field game(MFG) theory to reveal the coupling among the devices by utilizing the large-scale property. Specifically, to obtain the optimal access strategy for each device, we derive the Hamilton-Jacobi-Bellman(HJB) equation which requires the statistical information of other devices.Moreover, to model the evolution of the states distribution in the system, we derive the Fokker-PlanckKolmogorov(FPK) equation based on the access strategy of devices. By solving the two coupled equations,we obtain the delay-optimal random access solution in an iterative manner with Lax-Friedrichs method. Finally, the simulation results show that the proposed scheme achieves significant performance gain compared with the conventional schemes.

Study on the cultural and aesthetic characters of national costume design

National costume not only show body language, but also body language and extends through the aesthetic psychology of space and aesthetic psychological sense, to convey the emotional body hidden vocabulary, the limited physical space converted into a form of osvcholoical unlimited imagination!

6G无线空口传输技术研究进展与展望

自20世纪80年代以来,移动通信已彻底改变世界,对人们的生活产生了深远影响.在5G成功商用的今天,人们又开始思考6G会是什么样子.作为下一代移动通信系统,6G不仅在频谱效率、时延、可靠性等通信KPI指标上提出了更高的要求,其内涵也将涉及人工智能、感知等新元素,远超传统意义上移动通信的范畴.为了实现6G愿景,迫切需要业界研究与之相适应的先进无线技术方案.本文重点介绍了6G无线空口多个研究方向的技术趋势和进展,包括信道编码技术、多址和波形技术、智能超表面技术、智能MIMO(multiple input multiple output)技术等,提出并初步验证了一系列创新技术点,如便车码、格码多址等.这些创新技术的提出,对6G愿景和KPI指标的实现起到有力的支撑作用.

Uncovering hidden nodes and hidden links in complex dynamic networks

Inferring network structures from available data has attracted much interest in network science;however,in many realistic networks,only some of the nodes are perceptible while others are hidden,making it a challenging task.In this work,we develop a method for reconstructing the network with hidden nodes and links,taking account of fast-varying noise and time-delay interactions.By calculating the correlations of available data with different derivative orders for multiple pairs of accessible nodes,analyzing and integrating the relationships between different correlations,and defining diverse hidden-node-related reconstruction motifs,we can effectively identify the hidden nodes and hidden links in the network.

Wireless communications empowered by reconfigurable intelligent surfaces: Model-based vs model-free channel estimation

Reconfigurable intelligent surfaces(RISs)are lately being attractive for their great potential in future sixth generation wireless communications(6G),which is attributed to their affordable energy consumption and easy integration.However,the large numbers of low-cost reflecting elements comprising RISs impose challenges for channel acquisition in various RIS-based wireless applications,such as RIS-enhanced orthogonal frequency-division multiplexing and multi-user multipleinput multiple-output systems.In this article,we first overview the state-of-the-art RIS hardware architectures designed to assist channel estimation for RIS-empowered wireless communication systems.We also overview existing channel estimation approaches,which are categorized into model-based and model-free techniques,and discuss their advantages and limitations depending on the RIS deployment.Design challenges with RIS-empowered systems in terms of hardware and other parameter limitations are presented,together with future research directions for channel estimation in RIS-based wireless systems,such as RISs with extremely large numbers of elements,multi-hop communications with RISs,and frequency division duplexing for high mobility systems.

Simultaneous creation of multiple vortex-antivortex pairs in momentum space in photonic lattices

Engineering of the orbital angular momentum(OAM)of light due to interaction with photonic lattices reveals rich physics and motivates potential applications.We report the experimental creation of regularly distributed quantized vortex arrays in momentum space by probing the honeycomb and hexagonal photonic lattices with a single focused Gaussian beam.For the honeycomb lattice,the vortices are associated with Dirac points.However,we show that the resulting spatial patterns of vortices are strongly defined by the symmetry of the wave packet evolving in the photonic lattices and not by their topological properties.Our findings reveal the underlying physics by connecting the symmetry and OAM conversion and provide a simple and efficient method to create regularly distributed multiple vortices from unstructured light.

Multi-Function Uninterrupted Phase-Separation Passing System and its Control Method

At present, sudden load changes and terminal voltage fluctuations are two primary problems in the uninterrupted phase-separation passing (UPP) system. To further enhance the reliability of the UPP system and compensate for the voltage sag at the end of the traction power supply network caused by the suddenly connection of locomotive to the power grid, a multi-function uninterrupted phase-separation passing system (MUPPS) and its control strategy are proposed. It has the advantages of linear load change and improving power supply reliability. First, the topology and working principles of a MUPPS are studied;secondly, the current variation characteristics of the bridge arm when the power is continuously supplied by MUPPS during the phase-separation passing are analyzed. Then, the characteristics of a MUPPS to provide reactive power and stabilize the terminal voltage of the traction arm are analyzed. Then, the power transmission characteristics of a MUPPS under emergency working conditions are analyzed. The control strategy for the two conditions is proposed. Finally, simulation analysis and small capacity experiments are conducted. The theoretical analysis and test confirm the correctness and effectiveness of the MUPPS.

The clinical significance of human papillomavirus and p16^(INK4a)in vulvar tumors

Vulvar cancer is the fourth most common gynecological malignancy,with a global incidence of an estimated 45,240 new cases and 17,427 deaths in 2022.1 The 5-year survival rate for vulvar cancer is about 70%based on data from the SEER database.2 More than 90%of vulvar cancer was vulvar squamous cell carcinoma(SCC),which included keratinizing,non-keratinizing,basaloid,warty,and verrucous carcinoma.

Theory and techniques for“intellicise”wireless networks

With the acceleration of a new round of global scientific,technological,and industrial revolution,the next generation of information and communication technology,i.e.,6G,will inject new momentum into industry transformation and upgrading,as well as into economic innovation and development.This will subsequently promote a global industrial integration.Wireless communication will be ubiquitous in all areas of future society,supporting novel applications with various performance requirements.

Genome-wide association study of callus induction variation to explore the callus formation mechanism of rice

Rice(Oryza sativa) is one of the most widely cultivated food crops, worldwide. Tissue culture is extensively used in rice breeding and functional genome research. The ability to induce callus determines whether a particular rice variety can be subjected to tissue culture and Agrobacterium-mediated transformation. Over the past two decades, many quantitative trait loci(QTLs)related to callus induction traits have been identified;however, individual genes associated with rice callus induction have not been reported. In this study, we characterized three callus-induction traits in a global collection of 510 rice accessions. A genome-wide association study of the rice population in its entirety as well as subpopulations revealed 21 significant loci located in rice callus induction QTLs. We identified three candidate callus induction genes, namely CRL1, Os BMM1, and Os SET1, which Rese are orthologs of Arabidopsis LBD17/LBD29, BBM, and SWN,respectively, which are known to affect callus formation.Furthermore, we predicted that 14 candidate genes might be involved in rice callus induction and showed that RNA interference(RNAi)-mediated disruption of Os IAA10 inhibited callus formation on tissue culture medium.Embryo growth in the Os IAA10 RNAi line was not inhibited by synthetic auxin(2,4-D) treatment, suggesting that Os IAA10 may perceive auxin and activate the expression of downstream genes, such as CRL1, to induce callus formation. The significant loci and candidate genes identified here may provide insight into the mechanism underlying callus formation in rice.

调制金属有机框架节点拓扑构型用于促进苯胺高效催化氧化

金属有机框架所具有的拓扑构型丰富的可调控性是其独特于传统多孔材料的显著特征之一.通过简单易行的方式调控组成构建金属有机框架的节点构型从而改变其拓扑堆积方式,并研究其催化性能的变化,这有助于深入理解催化反应的构效关系并为高效催化剂的开发提供指导.本文以高稳定性的Hf-UiO-66作为研究对象,合成了具有Hf_(12)节点的hcp构型UiO-66-hcp以及具有Hf_(6)节点的fcu构型UiO-66-fcu,其中hcp构型材料对苯胺选择性氧化至氧化偶氮苯的反应具有显著优于fcu构型材料的催化性能,且具有优异的催化稳定性及底物拓展性.因节点结构改变所致的拓扑构型差异显著影响了催化活性,且性能差异适用于多种底物及网状化学同系物UiO-67,其来源可能在于Hf_(12)及Hf_(6)节点中桥联μ-OH的空间环境差异.

Exploiting cooperative multipath –Doppler diversity in relay-assisted high-speed train communications

Severe doubly selective channel fading,or the time- and frequency-selective fading,prevailing in highspeed train(HST) communications,has been a critical issue that hinders the improvement of system efficiency and reliability.In this paper,a relay-assisted HST communication system is considered,and a low-complexity but effective scheme is proposed to cooperatively exploit the joint multipath–Doppler diversity of both the direct link and the relay link and thus to mitigate the negative effect of channel fading and improve the system reliability.In particular,using a special precoding structure followed by two-dimensional Fourier transform,the transmit signal is generated which in effect parallelizes the doubly selective fading channel.As a result,in the transform domain,pointwise combining and equalization,which are of linear complexity,become feasible and diversity gain is obtained.The maximal diversity order is then analyzed under the amplify-and-forward relay settings,which reveals that by cooperative relaying the joint multipath–Doppler diversity of both links can be well exploited.Simulation results verified our analysis.

HucMSC-Ex alleviates inflammatory bowel disease via the lnc78583-mediated miR3202/HOXB13 pathway

As a group of nonspecific inflammatory diseases affecting the intestine,inflammatory bowel disease(IBD)exhibits the characteristics of chronic recurring inflammation,and was proven to be increasing in incidence(Kaplan,2015).IBD induced by genetic background,environmental changes,immune functions,microbial composition,and toxin exposures(Sasson et al.,2021)primarily includes ulcerative colitis(UC)and Crohn's disease(CD)with complicated clinical symptoms featured by abdominal pain,diarrhea,and even blood in stools(Fan et al.,2021;Huang et al.,2021).

Parametric amplification of Rydberg six- and eight-wave mixing processes

We study the parametric amplification of electromagnetically induced transparency-assisted Rydberg six-and eight-wave mixing signals through a cascaded nonlinear optical process in a hot rubidium atomic ensemble both theoretically and experimentally. The shift of the resonant frequency(induced by the Rydberg–Rydberg interaction) of parametrically amplified six-wave mixing signal is observed. Moreover, the interplays between the dressing effects and Rydberg–Rydberg interactions in parametrically amplified multiwave mixing signals are investigated. The linear amplification of Rydberg multiwave mixing processes with multichannel nature acts against the suppression caused by Rydberg–Rydberg interaction and dressing effect.

Research on the evaluation model and demonstration of patentee's discourse power:A case study of cyber security

With the deep meaning of discourse power in international relations,national discourse power has become an important manifestation of national soft power.This paper analyzes the main elements of the discourse power of patentee to speak,constructs the evaluation model,and selects the evaluation indexes related to the six characteristics according to the methods of patent measurement and social network analysis.In the empirical research stage,taking the field of network security as an example,the validity and reliability of the evaluation system are tested,and the accuracy of the evaluation results is tested by correlation.It is found that the evaluation system of discourse power of patentee to speak in the field of network security proposed in this paper is effective.

Data recovery with sub-Nyquist sampling:fundamental limit and a detection algorithm

While the Nyquist rate serves as a lower bound to sample a general bandlimited signal with no information loss,the sub-Nyquist rate may also be sufficient for sampling and recovering signals under certain circumstances.Previous works on sub-Nyquist sampling achieved dimensionality reduction mainly by transforming the signal in certain ways.However,the underlying structure of the sub-Nyquist sampled signal has not yet been fully exploited.In this paper,we study the fundamental limit and the method for recovering data from the sub-Nyquist sample sequence of a linearly modulated baseband signal.In this context,the signal is not eligible for dimension reduction,which makes the information loss in sub-Nyquist sampling inevitable and turns the recovery into an under-determined linear problem.The performance limits and data recovery algorithms of two different sub-Nyquist sampling schemes are studied.First,the minimum normalized Euclidean distances for the two sampling schemes are calculated which indicate the performance upper bounds of each sampling scheme.Then,with the constraint of a finite alphabet set of the transmitted symbols,a modified time-variant Viterbi algorithm is presented for efficient data recovery from the sub-Nyquist samples.The simulated bit error rates(BERs)with different sub-Nyquist sampling schemes are compared with both their theoretical limits and their Nyquist sampling counterparts,which validates the excellent performance of the proposed data recovery algorithm.