新时代轨道交通专业高职生国际化素养提升路径研究

中国铁路对外援建服务了越来越多的沿线国家,促进了沿线区域的繁荣与稳定,中国铁路已然成为我国新的“外交名片”。因此,本文对“中国铁路人才走出去”倡议实施中的关键问题进行了探讨,包括我国对外援建人才的培养以及轨道交通专业高职生在外语交流能力、国际素养等方面的提升,同时也探讨了轨道行业业务交流和传播中国铁路文化的重要性。在这个背景下,铁路高职院校学生国际化素养的提升路径显得尤为重要。

High Areal Capacity and Long Cycle Life Flexible Mild Quasi-Solid-State Ag-Zn Battery with Dendrite-Free Anode

Silver-zinc(Ag-Zn)batteries are a promising battery system for flexible electronics owing to their high safety,high energy density,and stable output voltage.However,poor cycling performance,low areal capacity,and inferior flexibility limit the practical application of Ag-Zn batteries.Herein,we develop a flexible quasi-solid-state Ag-Zn battery system with superior performance by using mild electrolyte and binder-free electrodes.Copper foam current collector is introduced to impede the growth of Zn dendrite,and the structure of Ag cathode is engineered by electrodeposition and chloridization process to improve the areal capacity.This novel battery demonstrates a remarkable cycle retention of 90%for 200 cycles at 3 mA cm^(-2).More importantly,this binder-free battery can afford a high capacity of 3.5 mAh cm^(-2)at 3 mA cm^(-2),an outstanding power density of 2.42 mW cm^(-2),and a maximum energy density of 3.4 mWh cm^(-2).An energy management circuit is adopted to boost the output voltage of a single battery,which can power electronic ink display and Bluetooth temperature and humidity sensor.The developed battery can even operate under the extreme conditions,such as being bent and sealed in solid ice.This work offers a path for designing electrodes and electrolyte toward high-performance flexible Ag-Zn batteries.

Selection of Suitable Area and Analysis of Adaptability Difference of Prunus humilis

This paper delves into and assesses the differences in biological traits and fruit nutritional composition of 3 varieties of Prunus humilis introduced from 2 different regions.Results showed that(i)the contents of protein,total sugar,and calcium of No.5 variety were higher those of the other 2 varieties,which was recognized as the most suitable variety for fresh fruit;(ii)the comparison of leaf areas index and fruit shape index of 3 varieties shows that the fruit shape index and individual fruit weight of the introduced varieties were higher than those of the control,the diameter of individual fruit of the introduced varieties higher than that of the control indicated that they had a higher fruit hardness,more dry matter accumulation and better fruit quality,and that the introduction region was more suitable for scale-up of P.humilis;(iii)there was a positive correlation with the number of fruiting branches and there was a significant negative correlation with individual fruit weight,while the leaf area had a significant negative correlation with the number of fruiting branches.The introduced varieties can develop normally in the 2 testing areas,notably,No.5 variety performed better than No.4 and No.6.Improving management is the prerequisite for maintaining proper number of fruiting branches and high yield.

The Relationship between Overparenting and Adolescent Anxiety:The Mediating Role of Cognitive Avoidance

Background:Adolescent anxiety has a significant impact on physical and mental health,and overparenting is recognized as one of the major factors affecting adolescent anxiety.The objective of this study was to investigate the relationship between overparenting and adolescent anxiety,while also examining the mediating role of cognitive avoidance.Methods:Data were collected through a cross-sectional survey with 1931 valid responses using the Overparenting Scale,the Cognitive Avoidance Scale,and the Anxiety Self-Rating Scale.A structural equation modelling approach was used to test the mediating role of cognitive avoidance between overparenting and adolescent anxiety and to reveal the underlying mechanisms.The significance of the mediating effect was assessed based on maximum likelihood estimation.Differences in the mediating role of cognitive avoidance in the male and female samples were comparatively analyzed in the mediation effect analysis.Results:The study’s findings reveal a significant positive correlation between overparenting and adolescent anxiety(p<0.01),between overparenting and cognitive avoidance(p<0.01),and between cognitive avoidance and adolescent anxiety(p<0.01).Cognitive avoidance mediated the relationship between overparenting and adolescent anxiety.Overparenting can not only directly predict adolescent anxiety but also indirectly predict it through the mediating role of cognitive avoidance.Conclusion:This study validates the direct effect of overparenting on adolescent anxiety and reveals the mechanism of cognitive avoidance as a mediator.

Research Progress of QuEChERS Pretreatment Technique in the Detection of Multiple Pesticide Residues

The QuEChERS extraction technique is a pretreatment technique that has been rapidly applied in recent years and is widely used in the field of pesticide residues with many advantages. This technique is based on solid phase extraction (SPE), which uses the interaction between adsorbent and impurities in the matrix to achieve the purpose of purification. The method has easier operation and better purification effect than SPE. In this paper, the research progress of the QuEChERS technique in pesticide residue detection in different fields in recent years and its future development were reviewed, hoping to provide reference for further development and utilization of the QuEChERS technique in pesticide residue detection in the future.

金色梦想,一触即发——化学专业校外实践教学基地建设与思考

高等教育要适应世界潮流和时代变化,本科教育须进一步提高实践教学的比重,加强理论教学与实践教学相结合,完善协同育人机制。结合学科发展和企业发展需求,中山大学化学学院与金发科技股份有限公司(简称金发科技)共同建设大学生实践教学基地。本文以中山大学-金发科技本科实践教学基地为例,探讨大学生校外实践基地建设过程中遇到的问题以及实践基地的建设内容与成果体会。

电子商务领域违法犯罪热点问题研究——以探索两岸四地移动支付犯罪问题及其对策为例

在全球化、信息化的迅速发展的形势下,两岸四地有关金融领域的变革与创新有了长足的发展,其中个人开展交易活动中使用移动支付的形式进行金融交易就是一个例证。像任何新生事物一样,由于安全监管制度建立的滞后,其潜在的或已经暴露出的诸多隐患风险和犯罪情况,值得予以重视以跟踪研究。移动支付犯罪是指行为人利用移动支付的交易规则,技术漏洞监管缺位等实施侵犯公私财产、破坏金融管理秩序等违法犯罪行为。移动支付犯罪是在移动支付行业快速发展而监管缺位的背景下产生的,移动支付犯罪具有主体低龄化、手段智能化、类型多样化的特点。

一步法快速制备Mg^(2+)-壳聚糖/聚丙烯酰胺多功能复合水凝胶

文中采用一步法制备了具有黏附性、导电性、应变传感性能和自愈性的Mg^(2+)-壳聚糖(CS)/聚丙烯酰胺(PAM)双网络复合水凝胶。将Mg^(2+)直接加入到水凝胶反应体系中,原位形成金属离子交联键,避免了复杂的浸泡过程;此外,采用紫外光引发比热引发聚合更方便快捷。Mg^(2+)-CS/PAM水凝胶与多种材料具有较强的黏附能力,如橡胶、玻璃、塑料、金属、皮肤和石头等,其中与橡胶表面的黏附强度为32.09 kPa。由于其中丰富的自由离子,Mg^(2+)-CS/PAM水凝胶表现出良好的导电性和应变敏感性,可用于监测人体的大运动和细微运动。而且切割后的水凝胶在室温4 h内可完全愈合,还能拉伸至原来长度的4倍。

Healthy function and high valued utilization of edible fungi

Edible fungi are large fungi with high added value that can be utilized as resources.They are rich in high-quality protein,carbohydrate,various vitamins,mineral elements and other nutrients,and are characterized by high protein,low sugar,low fat and low cholesterol.In addition,edible fungi contain a variety of bioactive substances,such as polysaccharides,dietary fiber,steroids,polyphenols,and most of these compounds have antioxidant,anti-tumor and other physiological functions.This review comprehensively discusses the bioactive components and functional characteristics of edible fungi(such as antioxidant,anti-aging,hypolipidemic activities,etc.).Then the recent developments and prospect in the high-valued utilization of edible fungi are discussed and summarized.The objective of this review is to improve the understanding of health-promoting properties of edible fungi,and provide reference for the industrial production of edible fungi-based health products.

Simultaneous Detection and Removal of Formaldehyde at Room Temperature: Janus Au@ZnO@ZIF-8 Nanoparticles

The detection and removal of volatile organic compounds(VOCs) are of great importance to reduce the risk of indoor air quality concerns. This study reports the rational synthesis of a dual-functional Janus nanostructure and its feasibility for simultaneous detection and removal of VOCs.The Janus nanostructure was synthesized via an anisotropic growth method, composed of plasmonic nanoparticles,semiconductors, and metal organic frameworks(e.g.,Au@ZnO@ZIF-8). It exhibits excellent selective detection to formaldehyde(HCHO, as a representative VOC) at room temperature over a wide range of concentrations(from 0.25 to100 ppm), even in the presence of water and toluene molecules as interferences. In addition, HCHO was also found to be partially oxidized into non-toxic formic acid simultaneously with detection. The mechanism underlying this technology was unraveled by both experimental measurements and theoretical calculations: ZnO maintains the conductivity, while ZIF-8 improves the selective gas adsorption; the plasmonic effect of Au nanorods enhances the visible-light-driven photocatalysis of ZnO at room temperature.

Enhanced Reconfigurable Intelligent Surface Assisted mmWave Communication: A Federated Learning

Reconfigurable intelligent surface(RIS)has been proposed as a potential solution to improve the coverage and spectrum efficiency for future wireless communication.However,the privacy of users’data is often ignored in previous works,such as the user’s location information during channel estimation.In this paper,we propose a privacy-preserving design paradigm combining federated learning(FL)with RIS in the mmWave communication system.Based on FL,the local models are trained and encrypted using the private data managed on each local device.Following this,a global model is generated by aggregating them at the central server.The optimal model is trained for establishing the mapping function between channel state information(CSI)and RIS’configuration matrix in order to maximize the achievable rate of the received signal.Simulation results demonstrate that the proposed scheme can effectively approach to the theoretical value generated by centralized machine learning(ML),while protecting user’privacy.

Isolation,purification,structural characteristic and antioxidative property of polysaccharides from A.cepa L.var.agrogatum Don

Allium cepa L.var.agrogatum Don(ALAP)is commonly consumed in China as well as other regions and has various beneficial health effects.A novel acidic polysaccharide(named ALAP-21)was obtained from ALAP by ultrasonic and microwave-assisted extraction and purification using DEAE-52 anion exchange and Sephadex G-100 columns.The monosaccharide composition,structural and antioxidative properties of ALAP-21 were investigated by GC–MS chromatography,FT-IR and NMR spectroscopies and three antioxidative activity tests in vitro.The results showed that ALAP-21 was a heteropolysaccharide composed of glucose,galacturonic acid,mannose,galactose,arabinose,rhamnose,xylose,fructose and glucuronic acid with a relative molar ratio of 26.282:27.546:11.400:4.781:2.467:2.445:3.622:1.106:1.753,owning(1→4)-β-d-Glcp,(1→4)-β-d-GalAp6Me3OA,(1→4)-β-d-Galp6OMe,(1→2)-β-l-Rhap,(1→4)-β-d-Manp glycosidic linkages.(1→4)-β-d-Glcp and(1→4)-β-d-GalAp6Me3OA residues might be the main components of the sugar chain backbone of ALAP-21.Furthermore,ALAP-21 exhibited high potential for DPPH radicals(82.02%),hydroxyl radicals(53.33%)and superoxide anion radicals(50.28%).These results provide a reference for further research and rational development of ALAP polysaccharides.

Dynamic microwave-assisted extraction combined with liquid phase microextraction based on the solidification of a floating drop for the analysis of organochlorine pesticides in grains followed by GC

A convenient,cost-effective and fast method using dynamic microwave-assisted extraction and liquid phase microextraction based on the solidification of a floating drop was proposed to analyze organochlorine pesticides in grains including rice,maize and millet.Twelve samples can be processed simultaneously in the method.During the extraction process,10%acetonitrile-water solutions containing 110μL of n-hexadecane were used to extract organochlorine pesticides.Subsequently,1.0 g sodium chloride was placed in the extract,and then centrifuged and cooled.The n-hexadecane drops containing the analytes were solidifi ed and transferred for determination by gas chromatography-electron capture detector without any further filtration or cleaning process.Limits of detection for organochlorine pesticides were 0.97–1.01μg/kg and the RSDs were in the range of 2.6%–8.5%.The developed technology has succeeded in analyzing six real grains samples and the recoveries of the organochlorine pesticides were 72.2%–94.3%.Compared with the published extraction methods,the developed method was used to analyze organochlorine pesticides in grains,being more environmentally friendly,which is suitable for the daily determination of organochlorine pesticides.

Energy Efficient Transmission in Underlay CR-NOMA Networks Enabled by Reinforcement Learning

In order to improve the energy efficiency(EE)in the underlay cognitive radio(CR)networks,a power allocation strategy based on an actor-critic reinforcement learning is proposed,where a cluster of cognitive users(CUs)can simultaneously access to the same primary spectrum band under the interference constraints of the primary user(PU),by employing the non-orthogonal multiple access(NOMA)technique.In the proposed scheme,the optimization of the power allocation is formulated as a non-convex optimization problem.Additionally,the power allocation for different CUs is based on the actor-critic reinforcement learning model,in which the weighted data rate is set as the reward function,and the generated action strategy(i.e.the power allocation)is iteratively criticized and updated.Both the CU’s spectral efficiency and the PU’s interference constrains are considered in the training of the actor-critic reinforcement learning.Furthermore,the first order Taylor approximation as well as other manipulations are adopted to solve the power allocation optimization problem for the sake of considering the conventional channel conditions.According to the simulation results,we find that our scheme could achieve a higher spectral efficiency for the CUs compared to a benchmark scheme without learning process as well as the existing Q-learning based method,while the resultant interference affecting the PU transmission can be maintained at a given tolerated limit.

Effects of Different Nitrogen Applications on Soil Physical, Chemical Properties and Yield in Maize (<i>Zea mays</i>L.)

Application of nitrogen (N) fertilizer is one of the most important approaches on improving maize grain yield. However, as is known to all, overuse N fertilizer not only leads to decline of N use efficiency and maize yield, but also leads to potential risk to environment pollution. This experiment was conducted to determine the effects of N fertilizer applications with nine different treatments on soil physical-chemical characters and maize grain yield using hybrid variety Zhengdan 958 in 2011 and 2012. Results indicated that the soil bulk densities of T2 (CK) and T1 were the lowest compared to other treatments in 2011 and 2012, respectively, whereas the soil bulk density of T5 in 2011 and T3 in 2012 were higher than other treatments. The soil porosity and field capacity of T5 in 2011 and T3 in 2012 were lower than other treatments, but those of CK in 2011 and T1 in 2012 were higher than other treatments. The pH values of T3 to T7 were lower than other treatments. These results indicated that the soil bulk densities were increased, whereas the soil porosity, field capacity and values pH were decreased by N application at different stages. N application could increase the N contents of leaf and stem, whereas less or excess N application should not significant improve maize yield. Although the soil organic matter and total N contents of T3 were the highest in both 2011 and 2012, the yield of T4 is the highest in both 2011 and 2012. The application amount, period and times of N fertilizer were important to maize yield.

Cooperative Privacy Provisioning for Energy Harvesting Based Cognitive Multi-Relay Networks

In order to provide privacy provisioning for the secondary information,we propose an energy harvesting based secure transmission scheme for the cognitive multi-relay networks.In the proposed scheme,two secondary relays harvest energy to power the secondary transmitter and assist the secondary secure transmission without interfere the secondary transmission.Specifically,the proposed secure transmission policy is implemented into two phases.In the first phase,the secondary transmitter transmits the secrecy information and jamming signal through the power split method.After harvesting energy from a fraction of received radio-frequency signals,one secondary relay adopts the amplify-and-forward relay protocol to assist the secondary secure transmission and the other secondary relay just forwards the new designed jamming signal to protect the secondary privacy information and degrade the jamming interference at the secondary receiver.For the proposed scheme,we first analyze the average secrecy rate,the secondary secrecy outage probability,and the ergodic secrecy rate,and derive their closed-form expressions.Following the above results,we optimally allocate the transmission power such that the secrecy rate is maximized under the secrecy outage probability constraint.For the optimization problem,an AI based simulated annealing algorithm is proposed to allocate the transmit power.Numerical results are presented to validate the performance analytical results and show the performance superiority of the proposed scheme in terms of the average secrecy rate.

Co-feeding with DME:An effective way to enhance gasoline production via low temperature aromatization of LPG

The aromatization of light alkenes in liquefied petroleum gas (LPG) with and without dimethyl ether (DME) addition in the feed was investigated on a modified ZSM-5 catalyst.The results showed that under the given reaction conditions the selectivity of alkenes to high-octane gasoline blending components was markedly enhanced and the formation of propane and butanes was greatly suppressed with the addition of DME.It was also found that the distribution of C5+ components was changed a lot with DME addition into the LPG feed.The formation of branched hydrocarbons (mainly C6 C8 i-paraffin) and multi-methyl substituted aromatics,which are high octane number gasoline blending components,was promoted significantly,while the content of n-paraffins and olefins in C5+ components was decreased obviously,indicating that in addition to the oligomerization,cracking,hydrogen-transfer and dehydrogenation-cyclization of alkenes,the methylation of the formed aromatics and olefins intermediates also plays an important role in determining the product distribution due to the high reactivity of surface methoxy groups formed by DME.And this process,in combination with the syngas-to-methanol/DME technology,provides an alternative way to the production of high-octane gasoline from coal,natural gas or renewable raw materials.

A review and a statistical analysis of porosity in metals additively manufactured by laser powder bed fusion

Additive manufacturing(AM), or 3D printing, is an emerging technology that “adds” materials up and constructs products through a layer-by-layer procedure. Laser powder bed fusion(LPBF) is a powder-bed-based AM technology that can fabricate a large variety of metallic materials with excellent quality and accuracy. However, various defects such as porosity,cracks, and incursions can be generated during the printing process. As the most universal and a near-inevitable defect,porosity plays a substantial role in determining the mechanical performance of as-printed products. This work presents a comprehensive review of literatures that focused on the porosity in LPBF printed metals. The formation mechanisms,evaluation methods, effects on mechanical performance with corresponding models, and controlling methods of porosity have been illustrated and discussed in-depth. Achievements in four representative metals, namely Ti-6Al-4V, 316L, Inconel 718, and Al Si10Mg, have been critically reviewed with a statistical analysis on the correlation between porosity fraction and tensile properties. Ductility has been determined as the most sensitive property to porosity among several key tensile properties. This review also provides potential directions and opportunities to address the current porosity-related challenges.

Optimal construction method and demonstration application of multi-in-one station grounding system

Mutual influence may be driven by different models and operating mechanisms of grounding systems in multi-in-one substations.Even equipment damage and personal injury will occur in the event of a short-circuit or lightning strike.To meet the construction requirements of different multi-in-one substations,two typical application modes of grounding systems in multi-in-one substations are analyzed in this paper:plane and longitudinal layout schemes.First,the safety index and withstand voltage of secondary equipment in multi-in-one substations are introduced.Second,the plane layout scheme of grounding grids is examined.Based on a 35-kV multi-in-one substations in Shanghai,it was verified that the overall grounding grid needs to be laid to meet the safety of secondary equipment in the station.Finally,considering that it is feasible to rebuild the upper layer of a substation,the longitudinal layout scheme of the grounding grid in multi-in-one substations is also examined.Safety assessment is carried out in terms of aspects such as short-circuits and lightning strikes,and relevant optimization construction methods are analyzed.In this study,a real 35-kV substation in Shanghai was selected as an example.Simulation and field tests based on Current Distribution,Electromagnetic Fields,Grounding and Soil Structure Analysis(CDEGS)software verified that the proposed construction scheme can achieve safe operation of multi-in-one substations.This construction idea can also serve as a reference for the future construction of multi-in-one substations.

Feature and Tendency of Technology Transfer in Z-Park Patent Cooperation Network:From the Perspective of Global Optimal Path

Purpose:This study aims to provide a new framework for analyzing the path of technology diffusion in the innovation network at the regional level and industrial level respectively,which is conducive to the integration of innovation resources,the coordinated development of innovative subjects,and the improvement of innovation abilities.Design/methodology/approach:Based on the Z-Park patent cooperation data,we establish Inter-Enterprise Technology Transfer Network model and apply the concept of Pivotability to describe the key links of technology diffusion and quantify the importance of innovative partnerships.By measuring the topologically structural characteristics in the levels of branch park and the technosphere,this paper demonstrates how technology spreads and promotes overall innovation activities within the innovation network.Findings:The results indicate that:(1)Patent cooperation network of the Z-Park displays heterogeneity and the connections between the innovative subjects distribute extremely uneven.(2)Haidian park owns the highest pivotability in the IETTN model,yet the related inter-enterprise patent cooperation is mainly concentrated in its internal,failing to facilitate the technology diffusion across multiple branch parks.(3)Such fields as“electronics and information”and“advanced manufacturing”are prominent in the cross-technosphere cooperation,while fields such as“new energy”and“environmental protection technology”can better promote industrial integration.Research limitations:Only the part of the joint patent application is taken into account while establishing the patent cooperation network.The other factors that influence the mechanism of technology diffusion in the innovation network need to be further studied,such as financial capital,market competition,and personnel mobility,etc.Practical implications:The findings of this paper will provide useful information and suggestions for the administration and policy-making of high-tech parks.Originality/value:The value of this paper is to build a bridge between the massive amount of patent data and the nature of technology diffusion,and to develop a set of tools to analyze the nonlinear relations between innovative subjects.