一种新的双偶氮染料掺杂聚合物薄膜的光致双折射及偏振全息的研究

作为一种有可能作为永久信息存储的材料,合成出一种新的双偶氮材料(BA1)。当样品被波长为532nm的光激发时,几乎大部分BA1分子从反-反态转化到顺-顺态,产生了光致双折射。因此,研究了BA1分子掺杂的PMMA薄膜的光致双折射和透过信号与入射光强度的关系。实验结果表明:透过信号强度随着泵浦光的增强而增强。通过偏振态互相平行(SS)和垂直(SP)的两束偏振光用来研究偏振全息存储,结果表明SP光栅形成的衍射信号要比SS光栅的衍射信号强很多。     

Quantum Anti-Zeno Effect in Nuclear Decay

The acceleration of decay induced by frequency measurements,namely the quantum anti-Zeno effect(AZE),was first predicted by Kofman and Kurizki [Nature 405(2000) 546].The effect of the frequency measurements on nuclear β decay rate is analyzed based on the time-dependent perturbation theory.We present a detailed calculation of the decay rates of ~3H,~(60)Co(β~-type),~(22)Na,~(106)Ag(β~+ type) and ~(18)F,~(57)Co and ~(111)Sn(EC type)under frequency measurements.It is found that the effects of frequency measurements on the decay rates of β~+and β~-cases are different from the case of EC,and the smaller the β decay energy is,the more favorable it is to observe the AZE in experiment.Based on our analysis,it is suggested that possible experimental candidates should have a small decay energy and a reasonable half life(such as ~3H) for observing the AZE in β decay.     

基于ABAQUS的微细电火花超声振动主轴仿真研究

微细电火花技术凭借自身的特点和优势,在航空航天、医疗器械等领域发挥着重要的作用.超声振动辅助电火花加工在传统电火花加工中引入超声振动,加工精度和加工效率明显提高.作为核心部件,超声振动主轴的设计尤为重要.但传统设计过程,大大延长了研发周期和增加了成本,因此,采用仿真方式进行研究具有重要的意义.该文对设计的微细电火花超声...     

Discovery of β-Dihydroagarofuran-Type Sesquiterpenoids from the Leaves of Tripterygium wilfordii with Neuroprotective Activities

Nine undescribed dihydro-β-agarofuran sesquiterpenoid derivatives(1—9),along with a known analogue(10),were obtained from the leaves of Tripterygium wilfordii.Their gross structures were determined via extensive spectroscopic data,and the absolute configurations were elucidated by means of single-crystal X-ray diffraction analysis and electron circular dichroism(ECD)techniques,which include ECD exciton chirality,octant rule of saturated cyclohexanone and comparison between the experimental and calculated ECD spectra.All the isolated compounds were tested for their neuroprotective activities against H2O2-induced cell injury in human neuroblastoma SH-SY5Y cells.Compounds 5 and 6 improved cell viability by 16.15%and 15.12%compared with the H2O2 treated group at 25μmol·L^-1,respectively.     

氯钯共掺对Cs2TiBr6光电性能影响的第一性原理计算

全无机无铅钙钛矿Cs₂TiBr₆具有光电特性良好、带隙可调和环境友好等优点,是一种潜力巨大的光吸收材料。为改善Cs₂TiBr₆的相关性能,我们采用基于第一性原理的方法,针对Pd、Cl掺杂的Cs₂TiBr₆钙钛矿结构进行了研究。结果表明,用Pd取代Ti后产生杂质带,将原来间接带隙的Cs₂TiBr₆转变为直接带隙材料。用25.0%Pd掺杂后,晶体带隙值降低26%,掺杂后的晶体在320～415 nm近紫外光区吸收能力加强约50%,在645～900 nm的红外光区及近红外光区的光吸收能力加强约134%。在此基础上,将Cl与25.0%Pd共掺杂时,Cl掺杂不仅可以把Pd的形成能在单掺的基础上减小约9%,而且Cl的不同掺杂位置对材料的光电性能也有一定的影响。     

膜动态吸附传递过程的理论分析与研究

本文针对气体透过薄膜的传质过程,基于动态吸附、扩散传递的概念,根据Langmuir界面动态吸附理论,研究了存在定向传递时表面吸附量与平衡吸附量的差异,从而将膜相传质分为吸附、内部扩散和脱附三个动态过程.讨论了界面吸附、脱附与扩散对传质阻力的不同影响,建立了薄膜传质的串联阻力模型.     

Polyimide separators for rechargeable batteries

Separators are indispensable components of modern electrochemical energy storage devices such as lithium-ion batteries (LIBs).They perform the critical function...     

A Method of Domain Dictionary Construction for Electric Vehicles Disassembly

Currently, there is no domain dictionary in the field of electric vehicles disassembly and other domain dictionary construction algorithms do not accurately extract terminology from disassembly text, because the terminology is complex and variable. Herein, the construction of a domain dictionary for the disassembly of electric vehicles is a research work that has important research significance. Extracting high-quality keywords from text and categorizing them widely uses information mining, which is the basis of named entity recognition, relation extraction, knowledge questions and answers and other disassembly domain information recognition and extraction. In this paper, we propose a supervised learning dictionary construction algorithm based on multi-dimensional features that combines different features of extraction candidate keywords from the text of each scientific study. Keywords recognition is regarded as a binary classification problem using the LightGBM model to filter each keyword, and then expand the domain dictionary based on the pointwise mutual information value between keywords and its category. Here, we make use of Chinese disassembly manuals, patents and papers in order to establish a general corpus about the disassembly information and then use our model to mine the disassembly parts, disassembly tools, disassembly methods, disassembly process, and other categories of disassembly keywords. The experiment evidenced that our algorithms can significantly improve extraction and category performance better than traditional algorithms in the disassembly domain. We also investigated the performance algorithms and attempts to describe them. Our work sets a benchmark for domain dictionary construction in the field of disassembly of electric vehicles that is based on the newly developed dataset using a multi-class terminology classification.     

Thermus thermophilus木糖异构酶与木糖醇的分子对接及模型分析

在1BXB结构基础上, 通过分子对接方法构建木糖异构酶与抑制剂木糖醇的复合物模型, 为合理设计解除木糖醇对木糖异构酶的抑制及进一步揭示木糖醇对该酶抑制机理提供参考.     

轻度交联环糊精聚合物包结诱导自组装胶束的研究

合成了含β-环糊精的多取代单体(GMA)x-CD,经自由基聚合得到轻度交联的或高度支化的聚合物P(GMA)x-CD;同时由自由基共聚得到含有金刚烷侧基的疏水聚合物PtBA-ADA.研究表明,他们可在碱性水中通过β-CD和ADA间的包结络合作用形成胶束.当改变聚合物浓度比时,胶束尺寸在150~300 nm范围变化.TEM和AFM研究表明胶束具有核壳结构,核为疏水PtBA-ADA,壳为亲水(GMA)x-CD.通过对胶束壳CD基的化学交联,将胶束结构进一步固定化.