几种范德瓦耳斯铁电材料中新奇物性的研究进展

铁电材料因具有电场可调的自发极化,在各类功能器件中有着广泛的应用.受器件小型化发展趋势的影响,二维范德瓦耳斯铁电材料及其层状母体块材成为了铁电领域的重点研究对象之一.近年来,研究人员已经制备出了数种二维范德瓦耳斯铁电材料,并通过理论计算与实验结合的方法发现这些材料及其母体块材具有许多优良的、新奇的物理性质.本文主要介绍近年来几种范德瓦耳斯铁电材料的一些研究进展,包括体相范德瓦耳斯材料CuInP₂S₆的新奇物性的理论预测与实验证实,以及两类二维范德瓦耳斯铁电材料M₂X₂Y₆(M=金属, X=Si, Ge, Sn, Y=S, Se, Te), QL-M₂O₃ (M=Al, Y)及相关功能器件的理论设计,最后对范德瓦耳斯铁电材料蕴含的丰富物理内涵及其发展前景进行了简要探讨,希望能够为该领域的相关研究提供一些思路和参考.     

薄层电色谱技术的研究进展

薄层电色谱技术将电场力的作用引入薄层色谱的分离过程中,具有分离时间短、分辨率高等特点,将可能在物质分析分离中发挥重要作用.本文介绍了薄层电色谱仪器装置的设计、固定相和流动相的类型、薄层电色谱的应用等内容,总结了目前的研究工作中存在的主要问题,并展望了该技术未来的发展趋势,还介绍了与薄层电色谱有相似的毛细管电色谱和自由流电泳技术.引文献50篇.     

心之所向,得失平常——我的点滴科研体会

踏入物理科研领域的人,大概都是怀着一些梦想的。和他们中很多人一样,我最初对物理有兴趣,是基于各式各样科幻题材的电影和小说。之所以选择物理专业,也是因为不满足于仅仅一时沉迷幻想,而是希望真的去做些什么。不过对我来说,这个选择稍微寒碜了点:父母帮我选择的高考志愿落榜了,在父母和老师失望的眼神中,我没有选择复读,而是选择了自己想读的物理专业。就此,我与物理结下了不解之缘。     

Band engineering of double-wall Mo-based hybrid nanotubes

Hybrid transition-metal dichalcogenides(TMDs) with different chalcogens on each side(X-TM-Y) have attracted attention because of their unique properties. Nanotubes based on hybrid TMD materials have advantages in flexibility over conventional TMD nanotubes. Here we predict the wide band gap tunability of hybrid TMD double-wall nanotubes(DWNTs) from metal to semiconductor. Using density-function theory(DFT) with HSE06 hybrid functional, we find that the electronic property of X-Mo-Y DWNTs(X = O and S, inside a tube; Y = S and Se, outside a tube) depends both on electronegativity difference and diameter difference. If there is no difference in electron negativity between inner atoms(X) of outer tube and outer atoms(Y) of inner tube, the band gap of DWNTs is the same as that of the inner one. If there is a significant electronegativity difference, the electronic property of the DWNTs ranges from metallic to semiconducting, depending on the diameter differences. Our results provide alternative ways for the band gap engineering of TMD nanotubes.     

Power-law statistics of synchronous transition in inhibitory neuronal networks

We investigate the relationship between the synchronous transition and the power law behavior in spiking networks which are composed of inhibitory neurons and balanced by dc current. In the region of the synchronous transition, the avalanche size and duration distribution obey a power law distribution. We demonstrate the robustness of the power law for event sizes at different parameters and multiple time scales. Importantly, the exponent of the event size and duration distribution can satisfy the critical scaling relation. By changing the network structure parameters in the parameter region of transition, quasicriticality is observed, that is, critical exponents depart away from the criticality while still hold approximately to a dynamical scaling relation. The results suggest that power law statistics can emerge in networks composed of inhibitory neurons when the networks are balanced by external driving signal.     

LB膜中NMOB分子构象的研究

利用DFTB3LYP/4-31G^*方法,对2-硝基-5-(N-甲基-N-十八烷基)氨基苯甲酸(NMOB)进行研究。计算结果发现,苯环的5位碳原子、氨基氮原子以及十八烷基链上与其最临近的两个碳原子所组成的两面角(D)约为90ⅲ时,NMOB有最稳构象,在NMOB自交替膜中,NMOB即以这种构象存在;而D=180ⅲ时,体系总能量较最稳构象高出31.57kJ/mol,这种构象存在于NMOB/花生酸镉(CdA)交替膜中,较小的能量差异使NMOB容易在两种构象之间进行转化,在NMOB/花生酸镉(CdA)交替膜中因受到花生酸直立构象紧密排列的诱导作用,NMOB分子以能量相对较高的构象存在。     

固体表面分子的自组装结构与调控机制

固体表面有机分子自组装是合成低维超分子材料和对固体表面进行功能化的重要途径.本文主要介绍了利用理论计算与扫描隧道显微镜实验相结合的手段研究固体表面分子自组装机制及结构与物性调控的相关工作.主要聚焦于几种由弱相互作用主导的分子自组装过程,从影响固体表面功能分子自组装过程的基本要素出发,如固体表面性质、功能分子的结构、功能分子间相互作用的类型和强度以及有卤族元素增原子参与的组装等,介绍了这些要素在构筑并调控分子自组装结构中的作用,理解固体表面功能分子自组装结构的调控机制,最后对如何实现分子自组装结构及物性的可控调制进行了展望,为设计新型低维超分子网格结构提供思路.     

碳离子束辐照处理对牛至精油微胶囊的缓释特性及抗鸡球虫病活性的影响

利用不同剂量的碳离子束辐照处理牛至精油微胶囊,研究对其缓释特性及抗鸡球虫病活性的影响。研究结果表明,通过碳离子束处理的牛至精油微胶囊,其主要活性成分百里香酚和香芹酚含量未发生变化,辐照处理后反应收率及产品的生物活性均提高,其中400 Gy剂量处理的牛至精油微囊的收率和生物活性均最高,收率达68.44%。通过对感染柔嫩艾美耳球虫的小鸡喂食后,其盲肠和十二指肠肿胀明显减轻,血液性内容物明显减少,血便指数在感染的第七天已降为0,抗球虫指数（ACI）达到179.39。The purpose of this study is using different doses of carbon ion beam irradiation on oregano essential oil microcapsules, to investigate function of control release and anticoccidial activity in chickens. The results showed that the content of main components in oregano essential oil microcapsules after carbon ion beam irradiation, thymol and carvacrol, have little change. Moreover, it can obtain more object products and better bioactivity after the irradiation treatment. Among these different doses of irradiation, our findings showed that Microcapsule groups with 400 Gy dose irradiation showed the highest yield (68.44%) and the best anticoccidial activity. After feeding chickens infected with Eimeria tenella, the swelling of caecum and duodenum were significantly mitigated and blood contents were also significantly reduced. The bloody stool index of chickens was as low as zero on the seventh day of infection, and the anticoccidial index (ACI) is 179.39.     

核辐照技术在中药领域中的应用

核辐照应用于中药领域的研究得到人们广泛关注。综述了核辐照在中草药的栽培、育种和消毒等方面的应用, 指出辐照诱变技术与生物技术相结合将为提高细胞突变率和加快中草药遗传改良开辟广阔前景。The application of nuclear irradiation in the field of traditional Chinese medicine has received much attention. In this paper we reviewed the application of nuclear radiation on the cultivation, breeding and disinfection of traditional Chinese medicine, and pointed out that the combination of radiation induced mutagenesis and biological technology would promise broad prospects for increasing the cellular mutation rate and speeding up the genetic improvement of traditional Chinese medicine.