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A universal strategy for achieving dual cross-linked networks to obtain ultralong polymeric room temperature phosphorescence

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Science China Chemistry 2023年第4期66卷 1161-1168页

作者： yifan niu Yan Guan Chunye Long Chaofan Ren Jiwen Lu Chanjuan Jin Ping Wang Xinghe Fan He-Lou Xie Key Laboratory of Environment-friendly Chemistry and Application of Ministry of Education Key Laboratory of Polymeric Materials and Application Technology of Hunan Province and Key Laboratory of Advanced Functional Polymer Materials of Colleges and Universities of Hunan ProvinceCollege of ChemistryXiangtan UniversityXiangtan 411105China Beijing National Laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry and Physics of Ministry of EducationCenter for Soft Matter Science and EngineeringCollege of Chemistry and Molecular EngineeringPeking UniversityBeijing 100871China

Efficient polymeric room-temperature phosphorescence(PRTP)with excellent processability and flexibility is highly desirable but still faces formidable ***,a general strategy is developed for efficient PRTP through photo-polymerization of phosphor monomers and N-isopropylacrylamide(NIPAM)spontaneously without a *** ultralong lifetime of 3.54 s with afterglow duration time of 25 s and decent phosphorescent quantum efficiency of 13%are *** efficient PRTP has been demonstrated to be derived from the synergistic effect of the covalent and hydrogen bonds networks formed through photo-polymerization of *** electron paramagnetic resonance(EPR)spectra confirmed that methyl radicals are generated under the irradiation of ultraviolet light and promote the formation of covalent cross-linking *** strategy has also been proved to be generalizable to several other phosphor ***,the polymer films display ultrahigh temperature resistance with long afterglows even at 140℃ and unexampled ultralong lifetime of 2.45 s in aqueous *** work provides a simple and feasible avenue to obtain efficient PRTP.

关键词： universal strategy ultralong polymeric room temperature phosphorescence dual cross-linked networks photopolymerization crosslinker

The chance of sodium titanate anode for the practical sodium-ion batteries

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Chinese Journal of Chemical Engineering 2024年第8期72卷 226-244页

作者： Feng Chen Haoyu Li Xianyan Qiao Ruoyang Wang Changyan Hu Ting Chen yifan niu Benhe Zhong Zhenguo Wu Xiaodong Guo School of Chemical Engineering Sichuan UniversityChengdu 610065China Institute for Advanced Study Chengdu UniversityChengdu 610106China Chengdu No.7 High School Chengdu 6100412China

Supporting sustainable green energy systems,there is a big demand gap for grid energy *** storage,especially sodium-ion batteries(SIBs),have advanced significantly and are now emerging as a feasible alternative to the lithium-ion batteries equivalent in large-scale energy storage due to their natural abundance and prospective inexpensive *** various anode materials of SIBs,beneficial properties,such as outstanding stability,great abundance,and environmental friendliness,make sodium titanates(NTOs),one of the most promising anode materials for the rechargeable ***,there are still enormous challenges in application of NTO,owing to its low intrinsic electronic conductivity and collapse of *** research on NTOs is still in its infancy;there are few conclusive reviews about the specific function of various modification ***,we summarize the typical strategies of optimization and analysis the fine structures and fabrication methods of NTO anodes combined with the application of in situ characterization *** work provides effective guidance for promoting the continuous development,equipping NTOs in safety-critical systems,and lays a foundation for the development of NTO-anode materials in SIBs.

关键词： Sodium titanates Sodium-ion batteries Modification methods Electronic materials Electrochemistry Synthesis

Efficient Chemical Prelithiation with Modificatory Li^(+) Solvation Structure Enabling Spatially Homogeneous SEI toward High Performance SiO_(x) Anode

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Chinese Journal of Chemistry 2024年第17期42卷 2056-2065页

作者： Ruoyang Wang Yuqing Wu yifan niu Qing Yang Haoyu Li Yang Song Benhe Zhong Liwen Yang Ting Chen Zhenguo Wu Xiaodong Guo School of Chemical Engineering Sichuan UniversityChengduSichuan 610065China Chengdu No.7 High School ChengduSichuan 6100412China Institute for Applied Materials(IAM) Karlsruhe Institute of Technology(KIT)Hermann-von-Helmholtz-Platz1D-76344 Eggenstein-LeopoldshafenGermany Institute for Advanced Study Chengdu UniversityChengduSichuan 610106China

Chemical prelithiation is widely proven to be an effective strategy to address the low initial coulombic efficiency(ICE)of promising SiO_(x) *** the reagent composition has been widely explored,the Li^(+) solvation structure,which practically plays the cornerstone role in the prelithiation ability,rate,uniformility,has rarely been explored.A novel environmentally-friendly reagent with weak solvent cyclopentyl methyl ether(CPME)is proposed that enables both improved ICE and spatial homogeneous solid electrolyte interphase(SEl).And the prelithiation behavior and mechanism were explored focused on the Li^(+) solvation *** theoretical investigation and spectroscopic results suggest that weak solvent feature of CPME reduces the solvent coordination number and decreases the Li^(+) desolvation energy.

关键词： Lithium-ion battery SiO_(x)anode Prelithiation Weak solvent Homogeneous SEI Energy conversion Desolvation energy

Time-dependent color-tunable room temperature phosphorescence from unusual conformational transitions in phenothiazine polymers under UV irradiation

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Science China Chemistry 2024年

作者： Jiwen Lu yifan niu Chanjuan Jin Chengheng Wu Hanyu Wang Yan Guan Ping Wang Xinghe Fan Key Lab of Environment-Friendly Chemistry and Application of Ministry of Education Key Laboratory of Polymeric Materials and Application Technology of Hunan Province Key Laboratory of Advanced Functional Polymer Materials of Colleges Universities of Hunan ProvinceCollege of Chemistry Xiangtan University Beijing National Laboratory for Molecular Sciences Key Laboratory of Polymer Chemistry and Physics of Ministry of Education Center for Soft Matter Science and Engineering College of Chemistry and Molecular Engineering Peking University

Achieving color-tunable room-temperature phosphorescence(RTP), especially including blue RTP from a single-component polymer still faces a formidable challenge. Herein, we wisely choose conformation-dependent phenothiazine with trifluoromethyl substituent as the side group of the phosphor monomer(CzPT) and then copolymerize it with N-isopropylacrylamide(NIPAM) through photopolymerization to obtain polymers PPCzPTs. Time-dependent color-tunable phosphorescence from unusual quasi-equatorial(eq) to quasi-axial(ax) conformers are obtained, and the RTP color changes from orange(550 nm) to blue(470 nm) with phosphorescence lifetime up to 0.96 s. The theoretical calculations confirm that the quasi-axial conformer is the preferred structure that facilitates the formation of intramolecular hydrogen bonds on the trifluoromethyl group. The EPR spectra illustrate that the persistent UV irradiation generates radical cations to induce the conformational transitions first, followed by photopolymerization immobilizing the ax conformation in PPCzPTs. Applications of data encryption and anti-counterfeiting are fabricated to show prompt and delayed multicolor information. This work affords a simple and feasible avenue for two-dimensional color tunable room temperature phosphorescence from a single-component polymer.

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基于脑电的弹幕视频用户体验质量评估研究

信号处理 2023年第8期39卷 1399-1407页

作者：邬霞牛一帆北京师范大学人工智能学院北京100875 教育部智能技术与教育应用工程研究中心北京100875

弹幕视频是一种近年来发展迅速的新兴媒体传播形式,备受大众喜爱,但根据调查显示,部分用户认为弹幕严重影响了视频观看。为改善弹幕视频服务,用户体验质量(Quality of Experience,QoE)的评估迫在眉睫。然而,现有用户体验质量评价方法存... 详细信息

弹幕视频是一种近年来发展迅速的新兴媒体传播形式,备受大众喜爱,但根据调查显示,部分用户认为弹幕严重影响了视频观看。为改善弹幕视频服务,用户体验质量(Quality of Experience,QoE)的评估迫在眉睫。然而,现有用户体验质量评价方法存在主观因素导致的虚假反馈、反馈不够及时、数据度量关系难以衡量等局限性。在这种情况下,脑电图(electroencephalogram,EEG)因具有无法伪装、高时间分辨率、数据更具统计学意义等优势,已经初步应用于视听刺激的主观评估。结合以上优势,本文提出将EEG突破性地应用于弹幕视频的QoE评估。本研究基于相锁值构建了功能连接特征脑网络,提取了高/低两种QoE水平下的成对差异网络,并基于该网络通过机器学习方法构建评估模型。该评估模型平均分类准确率达到80%,揭示了对于不同类型视频用户产生不同QoE时大脑区域协作的变化模式,并提出与QoE高度相关的额叶为主要会聚区域。以上研究结果表明,该评估模型能真实记录用户观看视频时的生理和心理活动,研究结果为改善弹幕视频服务提供了神经生理学依据。

关键词：弹幕视频用户体验质量脑电图脑-机接口

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汉墓壁画中的猪形雨神考

中原文物 2024年第5期 112-117页

作者：牛一帆南阳市汉画馆河南南阳473000

2003年,河南洛阳尹屯发现了一座新莽时期的大型壁画墓,在中室墓顶东北坡有一神人骑双首连体猪的奇特画面。壁画中双首猪的形象特征与我国古代传说中的“并封”相吻合。“并封”在古人的信仰中不仅是生殖神而且兼具雨水神,而猪所具有的... 详细信息

2003年,河南洛阳尹屯发现了一座新莽时期的大型壁画墓,在中室墓顶东北坡有一神人骑双首连体猪的奇特画面。壁画中双首猪的形象特征与我国古代传说中的“并封”相吻合。“并封”在古人的信仰中不仅是生殖神而且兼具雨水神,而猪所具有的旺盛生殖能力与预报雨水的气象功能是“并封”被奉为雨水神形象的客观依据。双首猪壁画所在墓中的位置与汉代祭祀雨神的方位相一致,同时又与雷神共处一画中,显示出与雷神的组合关系,符合“雷雨相伴”的气象神图像配置规律。因此该壁画墓中的双首猪就是我国古代传说的猪形雨神并封的形象。

关键词：洛阳尹屯汉墓壁画双首连体猪雨神并封

纳米碳材料/热塑性树脂层间增韧热固性树脂基复合材料研究进展

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复合材料学报 2022年第2期39卷 528-543页

作者：姚佳伟冯瑞瑄牛一凡牛康民中国民航大学中欧航空工程师学院天津300300 北京科技大学材料科学与工程学院北京100083

碳纤维增强环氧树脂复合材料(CF/EP)由于其优异的力学性能,被大量应用于工业中,但薄弱的层间性能限制了其优势性能的发挥。层间增韧是有效解决该问题的技术之一。随着材料科学与技术的发展,热塑性树脂、纳米碳材料先后被应用于层间增韧... 详细信息

碳纤维增强环氧树脂复合材料(CF/EP)由于其优异的力学性能,被大量应用于工业中,但薄弱的层间性能限制了其优势性能的发挥。层间增韧是有效解决该问题的技术之一。随着材料科学与技术的发展,热塑性树脂、纳米碳材料先后被应用于层间增韧复合材料的研究中。综述了热塑性树脂、纳米碳材料及二者协同层间增韧复合材料的研究进展,分析了热塑/热固双相体系及与纳米碳材料协同增韧复合材料的作用机制,为后续纳米材料/热塑性树脂层间增韧复合材料的研究提供了方向和参考。

关键词：纳米碳材料热塑性树脂层间增韧复合材料增韧增强

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基于非线性数据融合的设备多阶段寿命预测

信息与控制 2019年第6期48卷 729-737页

作者：牛一凡邵景峰西安工程大学管理学院陕西西安710600

为解决设备监测数据具有维数高、非线性且退化过程中存在多阶段的问题,提出了一种基于非线性数据融合和多阶段退化的设备寿命预测模型.首先,利用神经网络理论中的自编码器对表征设备退化的多维参数进行了融合,构建出设备的退化指示量;然... 详细信息

为解决设备监测数据具有维数高、非线性且退化过程中存在多阶段的问题,提出了一种基于非线性数据融合和多阶段退化的设备寿命预测模型.首先,利用神经网络理论中的自编码器对表征设备退化的多维参数进行了融合,构建出设备的退化指示量;然后,利用CUSUM算法提取出设备退化过程中的分段点;最后,构建了多阶段维纳退化模型,从而实现对设备寿命的预测.利用航空发动机状态监测数据对所提模型进行了验证,剩余寿命预测的平均误差为0.2545,低于传统的基于线性数据融合方法和基于单阶段维纳过程退化模型的寿命预测方法.结果证明,基于非线性数据融合的多阶段退化模型具有很好的鲁棒性,对设备的寿命预测更加精准.

关键词：寿命预测多阶段退化非线性数据融合

基于峰值力纳米力学模量成像技术的碳纤维/树脂复合材料界面尺寸与性能的原位表征

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复合材料学报 2017年第3期34卷 501-507页

作者：牛一凡杨赢孟积兴中国民航大学中欧航空工程师学院天津300300 东南大学土木工程学院工程力学系江苏省工程力学分析重点实验室南京210096 泰山体育产业集团国家体育用品工程技术研究中心德州253600

为准确测定复合材料界面结构的尺寸与性能,提出一种原位峰值力纳米力学模量成像(PF-QNM)技术,对其测试原理、校准方法和适用性进行分析,并采用PF-QNM技术对碳纤维/聚醚醚酮(T300/PEEK)、碳纤维/聚醚砜(T300/PES)和碳纤维/环氧树脂(T700/... 详细信息

为准确测定复合材料界面结构的尺寸与性能,提出一种原位峰值力纳米力学模量成像(PF-QNM)技术,对其测试原理、校准方法和适用性进行分析,并采用PF-QNM技术对碳纤维/聚醚醚酮(T300/PEEK)、碳纤维/聚醚砜(T300/PES)和碳纤维/环氧树脂(T700/TR1219B)三种复合材料的界面尺寸和各组分原位模量进行测试。结果标明:该方法的横向分辨率可以达到纳米尺度,测得树脂、界面、纤维区域的弹性模量数值呈梯度上升趋势,区分度明显,T300/PEEK、T300/PES和T700/TR1219B复合材料界面厚度分别为(69.3±7.9)nm、(101.3±10.2)nm和(48.4±5.4)nm。实验范围内,热固性复合材料界面厚度小于热塑性复合材料。对模量成像图统计分析可得,T300/PEEK、T300/PES和T700/TR1219B复合材料的树脂区平均弹性模量分别为4.36 GPa、4.96 GPa和3.59GPa,与其宏观弹性模量数值较为接近。

关键词：树脂基复合材料碳纤维界面原子力显微镜模量成像