Experimental study on mercury content in flue gas of coal-fired units based on laser-induced breakdown spectroscopy

Accurate measurement of trace heavy metal mercury(Hg) in flue gas of coal-fired units is great significance for ecological and environmental protection.Mixed gas was used to simulate the actual flue gas of a power plant in this study.A laser-induced breakdown spectroscopy(LIBS)system for Hg measurement in mixed gas was built to study the effect of mixed gas pressure,Hg concentration in mixed gas and delay time on Hg measurement.The experimental results show that the appropriate low mixed gas pressure can obtain high Hg signal intensity and signal to noise ratio.The Hg signal intensity and signal to noise ratio increased with the increase of Hg concentration in mixed gas.The Hg signal intensity and signal to noise ratio decreased with the increase in delay time.According to the above results,the optimized measurement conditions can be determined.Different Hg concentrations in mixed gas were quantitatively analyzed by the internal standard method and traditional calibration method respectively.The relative error of prediction of the test sample obtained by the internal standard method was within 11.11%.The relative error of prediction of the traditional calibration method was less than 14.54%.This proved that the internal standard method can improve the accuracy of quantitative analysis of Hg concentration in flue gas using LIBS.

Improvement on Quantitative Measurement of Fly Ash Contents Using Laser-Induced Breakdown Spectroscopy

Contents of fly ash are important factors for the operation of coal-fired plants. Real-time monitoring of coal and fly ash such as unburned carbon in fly ash can be an indicator of the combustion conditions. Because of the strong signal intensity and the relative simplicity of the LIBS (Laser- Induced Breakdown Spectroscopy) technique, LIBS can be applicable for real-time composition measurement of coal and fly ash. This research presented here focused on the clarification of the effects of plasma temperature and coexisting materials on quantitative measurement of fly ash contents. Quantitative capability of LIBS was improved using the proposed plasma temperature correction method. The CO2 effect was also discussed to accurately evaluate unburned carbon in fly ash in exhausts. Using the results shown in this study, quantitative measurement of fly ash contents has been improved for wider applications of LIBS to practical fields.

The new kid on the block in insect pest management:sprayable RNAi goes commercial

Insect pest damage to crops is a threat to global food security(Tilman et al.,2011).Climate change,the evolution of insecticide resistance,and the phasing out of insecticides due to environmental and safety concerns exacerbate this problem.Farmers urgently need safe and effective crop protection tools to sustainably generate yields that meet ever-increasing global demand.

浅析日本足球的发展对我国足球教育发展的启示

2023年日本足球队在卡塔尔世界杯打入决赛,展示出属于日本足球的传控体系,在世界足坛中大放异彩,坐实亚洲一流强队,成为其他强队不容小觑的对手,也打破了21世纪以来对亚洲足球的刻板印象。而中国足球却面临着十分严峻的发展形势。本文将运用文献资料法,从历史根源角度思考和探讨日本足球崛起的发展历程、发展经验,以此寻求中国足球发展以及教育的有效策略和实践路径,进而实现中国足球高质量发展。

“源-网-荷-储”式异质能流复合供能系统的研究现状及发展趋势

发展新一代“源-网-荷-储”式异质能流复合供能系统是能源行业高质量发展和提高可再生能源消纳水平的必然需求,加快其发展对构建多能互补、灵活、智慧的能源系统具有重要意义.目前,我国能源系统转型与升级进程加快,能源系统多能流交织、多品位分布、多时空尺度等特征愈发突出,给能源的高效利用带来新的理论和技术挑战.为实现异质能流系统的协同发展,还需要突破单一能流系统能量转换分析的局限,从能质、能量品位的角度,解释不同能源系统间的耦合逻辑并指导能源结构优化和能量管控,解决异质能流多尺度协同响应难等问题.因此,本文以“源-网-荷-储”式异质能流复合供能系统的构成和特征为切入,明晰了异质能流系统基础架构及各层间的关系,阐明了按质用能思想和能量品位相匹配对构建高效能量梯级利用系统、实现能量有序按需转化的重要性,总结了异质能流系统动态响应特性与协同调控、结构优化和能量管控等研究现状和挑战,并对未来能源系统的发展提出了一些建议.

RUP2 facilitates UVR8 redimerization via two interfaces

The plant UV-B photoreceptor UV RESISTANCE LOCUS 8(UVR8)exists as a homodimer in its inactive ground state.Upon UV-B exposure,UVR8monomerizes and interacts with a downstreamkey regulator,theCONSTITUTIVE PHOTOMORPHOGENIC 1/SUPPRESSOR OF PHYA(COP1/SPA)E3 ubiquitin ligase complex,to initiate UV-B signaling.Two WD40 proteins,REPRESSOR OF UV-B PHOTOMORPHOGENESIS 1(RUP1)and RUP2 directly interact with monomeric UVR8 and facilitate UVR8 ground state reversion,completing the UVR8 photocycle.Here,we reconstituted the RUP-mediated UVR8 redimerization process in vitro and reported the structure of the RUP2-UVR8^(W285A) complex(2.0A).RUP2 and UVR8^(W285A) formed a heterodimer via two distinct interfaces,designated Interface 1 and 2.The previously characterized Interface 1 is found between the RUP2 WD40 domain and the UVR8 C27 subregion.The newly identified Interface 2 is formed through interactions between the RUP2 WD40 domain and the UVR8 core domain.Disruption of Interface 2 impairedUV-B induced photomorphogenic development in Arabidopsis thaliana.Further biochemical analysis indicated that both interfaces are important for RUP2-UVR8 interactions and RUP2-mediated facilitation of UVR8 redimerization.Our findings suggest that the two-interface-interaction mode is adopted by both RUP2 and COP1 when they interact with UVR8,marking a step forward in understanding the molecular basis that underpins the interactions between UVR8 and its photocycle regulators.

Experimental study on pressure and temperature distributions for low mass flux steam jet in subcooled water

A low mass flux steam jet in subcooled water was experimentally investigated.The transition of flow pattern from stable jet to condensation oscillation was observed at relatively high water temperature.The axial total pressures,the axial and radial temperature distributions were measured in the jet region.The results indicated that the pressure and temperature distributions were mainly influenced by the water temperature.The correlations corrected with water temperature were given to predict the dimen-sionless axial pressure peak distance and axial temperature distributions in the jet region,the results showed a good agreement between the predictions and experiments.Moreover,the self-similarity property of the radial temperature was obtained,which agreed well with Gauss distribution.In present work,all the dimensionless properties were mainly dependent on the water temperature but weakly on the nozzle size under a certain steam mass flux.

Shape-controlled synthesis of liquid metal nanodroplets for photothermal therapy

The capping agents for liquid metal (LM) nanodroplets in aqueous solutions are restricted to thiol-containing and positively-charged molecules or macromolecules.However,both thiolate-metal complex and electrostatic interaction are liable to detachment upon strong mechanical forces such as sonication,leading to limited stability and applications.To address this,we utilized ultrasmall water soluble melanin nanoparticles (MNPs) as the capping agent,which exhibited strong metal binding capability with the oxide layer of gallium based LMs and resulted in enhanced stability.Interestingly,shape-controlled synthesis of LM nanodroplets can be achieved by the incorporation of MNPs.Various EGaln nanostructures including nanorice,nanosphere and nanorod were obtained by simply tuning the feed ratio,sonication time,and suspension temperature.Among these shapes,EGaln nanorice has the best photothermal conversion efficiency,which could be leveraged for photothermal therapy.

TriCTI:an actionable cyber threat intelligence discovery system via trigger-enhanced neural network

The cybersecurity report provides unstructured actionable cyber threat intelligence(CTI)with detailed threat attack procedures and indicators of compromise(IOCs),e.g.,malware hash or URL(uniform resource locator)of command and control server.The actionable CTI,integrated into intrusion detection systems,can not only prioritize the most urgent threats based on the campaign stages of attack vectors(i.e.,IOCs)but also take appropriate mitigation measures based on contextual information of the alerts.However,the dramatic growth in the number of cybersecurity reports makes it nearly impossible for security professionals to find an efficient way to use these massive amounts of threat intelligence.In this paper,we propose a trigger-enhanced actionable CTI discovery system(TriCTI)to portray a relationship between IOCs and campaign stages and generate actionable CTI from cybersecurity reports through natural language processing(NLP)technology.Specifically,we introduce the“campaign trigger”for an effective explanation of the campaign stages to improve the performance of the classification model.The campaign trigger phrases are the keywords in the sentence that imply the campaign stage.The trained final trigger vectors have similar space representations with the keywords in the unseen sentence and will help correct classification by increasing the weight of the keywords.We also meticulously devise a data augmentation specifically for cybersecurity training sets to cope with the challenge of the scarcity of annotation data sets.Compared with state-of-the-art text classification models,such as BERT,the trigger-enhanced classification model has better performance with accuracy(86.99%)and F1 score(87.02%).We run TriCTI on more than 29k cybersecurity reports,from which we automatically and efficiently collect 113,543 actionable CTI.In particular,we verify the actionability of discovered CTI by using large-scale field data from VirusTotal(VT).The results demonstrate that the threat intelligence provided by VT lacks a part of the threat context for IOCs,such as the Actions on Objectives campaign stage.As a comparison,our proposed method can completely identify the actionable CTI in all campaign stages.Accordingly,cyber threats can be identified and resisted at any campaign stage with the discovered actionable CTI.

RNA editing machinery in plant organelles

RNA editing is a type of post-transcriptional modification that includes nucleotide insertion/deletion or conversion. Different categories of RNA editing have been widely observed in distinct RNAs from divergent organisms. In flowering plants, RNA editing usually alters cytidine to uridine in plastids and mitochondria, playing important roles in various plant developmental processes, including organelle biogenesis, adaptation to environmental changes, and signal transduction. Numerous studies have demonstrated that a number of factors are involved in plant RNA editing, such as pentatricopeptide repeat(PPR) proteins, multiple organelle RNA editing factors(MORF, also known as RIP), organelle RNA recognition motif(ORRM) containing proteins,protoporphyrinogen IX oxidase 1(PPO1) and organelle zinc finger 1(OZ1). These factors play diverse roles in plant RNA editing due to their distinct characteristics. In this review, we discuss the functional roles of the individual editing factors and their associations in plant RNA editing.

Optimization of cold-end system of thermal power plants based on entropy generation minimization

Cold-end systems are heat sinks of thermal power cycles,which have an essential effect on the overall performance of thermal power plants.To enhance the efficiency of thermal power plants,multi-pressure condensers have been applied in some large-capacity thermal power plants.However,little attention has been paid to the optimization of the cold-end system with multi-pressure condensers which have multiple parameters to be identified.Therefore,the design optimization methods of coldend systems with single-and multi-pressure condensers are developed based on the entropy generation rate,and the genetic algorithm(GA)is used to optimize multiple parameters.Multiple parameters,including heat transfer area of multi-pressure condensers,steam distribution in condensers,and cooling water mass flow rate,are optimized while considering detailed entropy generation rate of the cold-end systems.The results show that the entropy generation rate of the multi-pressure cold-end system is less than that of the single-pressure cold-end system when the total condenser area is constant.Moreover,the economic performance can be improved with the adoption of the multi-pressure cold-end system.When compared with the single-pressure cold-end system,the excess revenues gained by using dual-and quadruplepressure cold-end systems are 575 and 580 k$/a,respectively.

探索新时代语境下的社交关系——喜茶白日梦计划

A.A.N致力于研究和探索新时代语境下人的行为,体验与空间之间的关;实践项目类型多元化且大多围绕着人们对于空间中的功能或精神需求展开;建筑空间与人们之间不应仅是单项的关系,空间与到来的人们之间的互动与对话,将让建筑更具有感染力。