聚吡咯@二氧化锰/碳纳米管薄膜电极的制备及在高性能锌离子电池中的应用

中性/弱酸性水系锌锰电池因其能量密度高、价格低廉、环境友好等优势受到广泛关注。然而,现有的二氧化锰正极材料存在导电性能差,在充放电过程中易于溶解等问题。这严重影响了电池的倍率性能和循环稳定性,阻碍了中性锌锰电池的应用。为了解决上述问题,本文设计了以碳纳米管(CNT)网络薄膜为导电基底沉积聚吡咯(PPy)包覆二氧化锰(PPy@MnO₂/CNT)的多级结构电极。碳纳米管和聚吡咯组装形成高比表面积的三维交联导电网络,为活性材料提供了快速的电子、离子传输通道;聚吡咯包覆纳米级二氧化锰能够有效地抑制二氧化锰的溶解,进而提升电池的倍率特性和循环稳定性。以PPy@MnO₂/CNT作为正极材料组装的水系锌锰电池在1 A·g^-1的电流密度下,比容量达到210 mAh·g^-1,循环1000圈后,电池依然具有较高的容量保持率(85.7%)。本工作的导电聚合物包覆活性物质的策略可为发展高稳定柔性储能器件提供新思路。     

Effect of the Choice of the Background on Two-Pion Inter-Ferometry

The effect of the choice of the background on the pion source parameters in two-Pion interferometry analyses in relativistic heavy-ion collisions is studied with the two-Pion interferometry at small relative momentum. The analytic relations between the pion source parameters from two-Pion interferometry analyses with different backgrounds are obtained, and comparison is made with the experimental measurements of the cental relativistic heavy-ion collisions of 1.8 A GeV Ar+Pb.     

Effects of Peppermint Essential Oil on Learning and Memory Ability in APP/PS1 Transgenic Mice

Objective: To explore the effect and mechanism of peppermint essential oil on learning and memory ability of APP/PS1 transgenic mice. Methods: Morris water maze test and shuttle box test were used to explore the changes in learning and memory ability of APP/PS1 transgenic mice after sniffing essential oil. The cellular status of neurons in the hippocampal CA1 region of the right hemisphere, Aβ deposition, oxidative stress level, and serum metabonomics were detected to explore its mechanism. Results: Sniffing peppermint essential oil can improve the learning and memory ability of APP/PS1 transgenic mice. Compared with the model group, the state of neurons in the hippocampal CA1 region of the peppermint essential oil group returned to normal, and the deposition of Aβ decreased. The MDA of brain tissue decreased significantly, and the activity of SOD and GSH-PX increased significantly to the normal level. According to the results of metabonomics, it is speculated that peppermint essential oil may improve cognitive function in AD by regulating arginine and proline metabolism, inositol phosphate metabolism, and cysteine and methionine metabolism.     

基于UNet深度学习算法的东海大型漂浮藻类遥感监测

基于语义分割神经网络UNet,利用GOCI(Geostationary Ocean Color Imager)卫星传感器数据,构建出能够有效提取大型漂浮藻类的深度学习模型,实现了对大型漂浮藻类信息端到端、像素到像素的分割识别.验证结果表明:所提出的深度学习模型对验证集中大型漂浮藻类的平均识别精度达到88.54％;通过与...     

Social learning with bounded confidence and heterogeneous agents

This paper investigates an opinion formation model in social networks with bounded confidence and heterogeneous agents. The network topologies are shaped by the homophily of beliefs, which means any pair of agents are neighbors only if their belief difference is not larger than a positive constant called the bound of confidence. We consider a model with both informed agents and uninformed agents, the essential difference between which is the informed agents have access to outside signals which are function of the underlying true state of the social event concerned. More precisely, the informed agents update their beliefs by combining the Bayesian posterior beliefs based on their private observations and weighted averages of the beliefs of their neighbors. The uninformed agents update their beliefs simply by linearly combining the beliefs of their neighbors. We find that the whole group can learn the true state only if the bound of confidence is larger than a positive threshold which is related to the population density. Furthermore, simulations show that the proportion of informed agents required for collective learning decreases as the population density increases. By tuning the learning speed of informed agents, we find the following: the higher the speed, the shorter the time needed for the whole group to achieve a steady state, and on the other hand, the higher the speed, the lower the proportion of agents with successful learning — there is a trade-off.     

金属-有机框架材料在光电催化水分解领域的研究进展

光催化分解水是将太阳能转化为化学能的有效手段之一. 相比于粉末光催化, 采用H型电解池的光 电催化方法具有材料选择范围大、 载流子迁移和分离效率高、 电极易于回收等优点. 近年来, 金属有机框架 材料(MOFs)在光电催化水分解领域得到越来越多的应用. 相比于传统无机催化剂, MOFs光电极具有比表面积大、 结构易于调控等独特优势. 本文按照MOFs的应用形式分为纯MOFs、 MOFs与其它催化剂的复合结构和MOFs衍生物3类, 总结了近年来MOFs在光电催化水分解领域的研究现状和进展, 介绍了光催化/电催化领域的部分典型研究成果, 最后讨论了MOFs在光电催化水分解领域研究的重点和热点, 并对其未来发展做出了展望.     

Approximation of Sojourn Times of Gaussian Processes

We investigate the tail asymptotic behavior of the sojourn time for a large class of centered Gaussian processes X, in both continuous- and discrete-time framework. All results obtained here are new for the discrete-time case. In the continuous-time case, we complement the investigations of Berman (Commun Pure Appl Math 38(5):519–528, 1985a and Probab Theory Relat Fields 20(1):113–124, 1987) for non-stationary X. A by-product of our investigation is a new representation of Pickands constant which is important for Monte-Carlo simulations and yields a sharp lower bound for Pickands constant.

     

Recent progress in microporous polymers from thermally rearranged polymers and polymers of intrinsic microporosity for membrane gas separation: Pushing performance limits and revisiting trade-off lines

Polymers are promising materials for gas separation membranes. However, the trade-off relationship between gas permeability and selectivity remains an obstacle for achieving polymer membranes that exhibit high gas permeation with desirable separation efficiency. Improving polymer microporosity is of interest in gas separation membranes to enhance gas transport behavior. Polymer modifications by (a) incorporating intrinsically microporous units and/or (b) increasing chain rigidity can enhance microporosity in conventional polymer membrane materials such as polyimides. These strategies are adopted for new classes of microporous polymers, thermally rearranged (TR) polymers, and polymers with intrinsic microporosity (PIMs), to maximize gas transport properties. Their outstanding gas separation performances have redefined the traditional trade-off lines. This review aims to explore the advances in microporous polymers for gas separation applications. The approaches on TR polymers and PIMs to enhance their microporosity are listed, and their developments are evaluated in the context of revisiting performance limits for industrially relevant gas separation applications.     

Erratum to “How people make friends in social networking sites—A microscopic perspective” [Physica A 391 (2012) 1877–1886]

We make a correction to the paper “How people make friends in social networking sites—A microscopic perspective”, Hu, H., Wang, X., Physica A, 391 (2012) 1877–1886.     

Photoluminescence from Er3+ ion and SnO2 nanocrystal co-doped silica thin films

Er3+ ions embedded in silica thin films co-doped by SnO2 nanocrystals are fabricated by sol-gel and spin coating methods. Uniformly distributed 4-nm SnO2 nanocrystals are fabricated, and the nanocrystals showed tetragonal rutile crystalline structures confirmed by transmission electron microscope and X-ray diffraction measurements. A strong characteristic emission located at 1.54 μm from the Er3+ ions is identified, and the influences of Sn doping concentrations on photoluminescence properties are systematically evaluated. The emission at 1.54 μm from Er3+ ions is enhanced by more than three orders of magnitude, which can be attributed to the effective energy transfer from the defect states of SnO 2 nanocrystals to nearby Er3+ ions, as revealed by the selective excitation experiments.