Fundamental Understanding on Selenium Electrochemistry:From Electrolytic Cell to Advanced Energy Storage

Selenium(Se),as an important quasi-metal element,has attracted much attention in the fields of thin-film solar cells,electrocatalysts and energy storage applications,due to its unique physical and chemical properties.However,the electrochemical behavior of Se in different systems from electrolytic cell to battery are complex and not fully understood.In this article,we focus on the electrochemical processes of Se in aqueous solutions,molten salts and ionic liquid electrolytes,as well as the application of Se-containing materials in energy storage.Initially,the electrochemical behaviors of Se-containing species in different systems are comprehensively summarized to understand the complexity of the kinetic processes and guide the Se electrodeposition.Then,the relationship between the deposition conditions and resulting structure and morphology of electrodeposited Se is discussed,so as to regulate the morphology and composition of the products.Finally,the advanced energy storage applications of Se in thin-film solar cells and secondary batteries are reviewed,and the electrochemical reaction processes of Se are systematically comprehended in monovalent and multivalent metal-ion batteries.Based on understanding the fundamental electrochemistry mechanism,the future development directions of Se-containing materials are considered in view of the in-depth review of reaction kinetics and energy storage applications.

Long-term Variation of the Solar Polar Magnetic Fields at Different Latitudes

The polar magnetic fields of the Sun play an important role in governing solar activity and powering fast solar wind.However,because our view of the Sun is limited in the ecliptic plane,the polar regions remain largely uncharted.Using the high spatial resolution and polarimetric precision vector magnetograms observed by Hinode from 2012 to 2021,we investigate the long-term variation of the magnetic fields in polar caps at different latitudes.The Hinode magnetic measurements show that the polarity reversal processes in the north and south polar caps are non-simultaneous.The variation of the averaged radial magnetic flux density reveals that,in each polar cap,the polarity reversal is completed successively from the 70°latitude to the pole,reflecting a poleward magnetic flux migration therein.These results clarify the polar magnetic polarity reversal process at different latitudes.

Preface: Frontiers in Astrophysics(Ⅱ)——A special issue dedicated to the 20th anniversary of RAA(2001–2020)

On the arrival of the 20 th anniversary of the journal,Research in Astronomy and Astrophysics(RAA),we see rapid progress in the frontiers of astronomy and astrophysics.To celebrate the birth and growth of RAA,a special issue consisting of 11 invited reviews from more than 30 authors,mainly from China,has been organized.This is the second volume of the special issues entitled Frontiers in Astrophysics published in RAA.The publication aims at evaluating the current status and key progress in some frontier areas of astronomy and astrophysics with a spirit of guiding future studies.

Magnetohydrodynamic process in solar activity

Magnetohydrodynamics is one of the major disciplines in solar physics. Vigorous magnetohydrodynamic process is taking place in the solar convection zone and atmosphere. It controls the generating and structuring of the solar mag- netic fields, causes the accumulation of magnetic non-potential energy in the solar atmosphere and triggers the explosive magnetic energy release, manifested as vi- olent solar flares and coronal mass ejections. Nowadays detailed observations in solar astrophysics from space and on the ground urge a great need for the studies of magnetohydrodynamics and plasma physics to achieve better understanding of the mechanism or mechanisms of solar activity. On the other hand, the spectac- ular solar activity always serves as a great laboratory of magnetohydrodynamics. In this article, we reviewed a few key unresolved problems in solar activity studies and discussed the relevant issues in solar magnetohydrodynamics.

Predict the spatiotemporal distribution of solar magnetic field and understand the evolutionary feature of solar activity

Solar activities are closely related to human production and daily life.The warm sunlight nurtures life on Earth,but the Sun also occasionally exhibits eruptive activities that significantly impact and threaten the Earth’s environment.Solar eruptive activities occur as large-scale energy release processes in localized regions of the solar atmosphere,primarily manifested through the enhanced electromagnetic radiation and energetic particle emissions in solar flares,as well as the ejection of mass and magnetic flux in coronal mass ejections(CMEs).

太阳立体探测任务设想

太阳空间探测在太阳物理前沿科学问题研究和空间天气预报应用研究方面具有重要的意义.人类在60余年的太阳空间探测活动中,取得了一系列重要成果,但仍存在诸多根本性重大问题有待解决.太阳立体探测可以克服单视角观测的局限,获取全方位、多要素的物理数据,促进解决太阳物理中的重大科学问题.本文介绍了太阳内部结构和磁场起源、太阳活动机理研究、太阳活动的全日球空间天气效应和空间天气预报模式研究4个科学目标,太阳立体探测任务空间布局、系统组成和探测器总体设计,以及太阳立体探测任务的有效载荷配置和主要技术指标.

On the possibility of predicting flare index and CME velocity using vector magnetograms

In this paper,106 active regions(ARs)in the visible solar hemisphere in solar cycle 24 whose maximum sunspot groups’areas were larger than 400μh were selected.The association of their flare index(Iflare),largest flare magnitude(Mflare),and fastest coronal mass ejection(CME)velocity(VCME)with the vector magnetic field parameters were examined,and attempts were made to predict Iflare,Mflare,and VCME using the vector magnetograms.Iflare and Mflare were found to have a good correlation with the total photospheric free magnetic energy density(Efree),the length of the magnetic neutral line with a steep horizontal magnetic gradient(LNL),and the area with strong magnetic shear(Aψ).Iflare and Mflare were also found to have a best correlation with Efree.However,VCME displayed a moderate correlation with these three magnetic field parameters with a best correlation with Aψ.Thus,Efree and Aψappear to be the best parameters that can be used to predict Iflare(Mflare)and VCME,respectively.Hence,the multiple linear regression fit is proposed more suitable to predict Iflare and Mflare because of the stronger forecasts obtained than those by the linear fit with one magnetic field parameter for Iflare and Mflare.However,the VCME forecasts are better obtained through the linear fit with Aψ.The majority of the ARs without any CMEs never produced any flare larger than X1.0 while having a relatively lower Efree,shorter LNL,and smaller Aψ.This suggests that the larger the largest flare in an AR is,the faster the fastest CME produced by the AR will be.