New crystal structure of molecular complex 1-piperidine carboxylate-piperidinium-H<Subscript>2</Subscript>O studied by X-ray single crystal diffraction

Piperidine absorbs CO2 and H2O in air to form a molecular complex： piperidium-l-piperidinecarboxylate-H2O. The structure of the complex was characterized by X-ray single crystal diffraction. The crystal structure was determined to be triclinic, space group P1^-with a=0.648 6（8） nm, b=0.809 200） nm, c= 1.357 1（16） nm, a=96.96706）°, β =102.506（15）°,γ=104.202 05）°, Z=2. The complex is stabilized via five hydrogen bonds between the three components, N-O electrostatic interaction and O-O interaction （electron transfer） betweenl-piperidinecarboxylate and H2O. Due to electron transference of carbamate ion, the oxygen atom in water molecule is strongly negatively charged and the O-H bond is considerably shorter than that of the free molecule of water. The formation of the molecular complex is a reversible process and will decompose upon heating. The mechanism of formation and stabilization is further investigated herein.     

石墨烯在锂离子电池材料中大有可为

锂离子电池是一种典型的可充电电池,在储能技术领域占主导地位,应用极为广泛。近年来,科技发展对锂离子电池提出了更高要求,包括高能量密度、高安全稳定性等,驱动着电池材料与结构不断创新发展。研制石墨烯基复合正极负极材料,是极为活跃的方向。在此,对锂离子电池的结构、面临的突出挑战以及石墨烯基正极和负极材料研究前沿进行了介绍,重点围绕石墨烯增强电极材料电学特性的基本原理和复合材料制备技术作了阐述,也提出了未来发展动向。     

SEM analysis of the changes of carbon layer structure of mesocarbon microbeads heat-treated at different temperatures

Mesocarbon microbeads (MCMB) with narrow size distribution, excellent sphericity and no obvious conglutination have been prepared with a coal tar pitch containing quinoline insolubles (QI) as the raw material. Optical microscopy and scanning electron microscopy (SEM) are used to examine the structure of the MCMB. It has been found that SEM technique shows the structural information of MCMB clearly in the form of micrographs even when the structure of MCMB is complex, while the optical technique is useful for analysis of the regular structure of the mesophase spheres but cannot be effectively used to analyze either the complex structure of the green MCMB or the structures of the further heat-treated ones at different temperatures. According to the characteristics of the carbon layers, the structures of the as-prepared MCMB in the present experiment could be classified as (I) Parallel Layer type structure and (2) Bent Layer type structure with the carbon layers gathering at one or two points in the MCMB. In the experiments, SEM is also utilized to investigate the structures of MCMB that are heat-treated at different temperatures. It has been found that the MCMB without any further heat-treatment show no layered-carbons, while the ones heat-treated at temperaturehigher than 1000℃ exhibit obvious layered carbons across their sections. When increasing the heat-treatment temperature, the carbon layers become thinner and flatter.     

原位观察电子束辐照下双壁碳纳米管的不稳定性

室温下利用高分辨透射电子显微镜原位观察了两端固定和一端固定、另一端自由的双壁碳纳米管在电子束辐照下的结构不稳定性.实验发现,在相同辐照条件下,两端固定的双壁碳纳米管首先径向持续均匀收缩,然后局部颈缩,最后在颈缩处断裂;一端固定、另一端自由的双壁碳纳米管轴向长度持续快速缩小,而径向收缩相对缓慢.我们利用最近提出的表面纳米曲率效应和能量束诱导非热激活效应基础上新发展的碳原子"融蒸"和"扩散"机制,对上述电子束辐照下双壁碳纳米管结构不稳定现象进行了全新、合理的解释.     

不同充水状态下隧道植绒排水管防除结晶的效果研究

为了研究不同充水状态下隧道植绒排水管防除结晶的效果,通过在普通PVC管内壁,采用热处理,将植绒膜光滑一侧紧贴PVC管内壁,选取绒毛长度分别为0.4 mm和0.8 mm;在两种不同充水条件下,对比分析普通PVC管、0.4 mm植绒PVC管以及0.8 mm植绒PVC管结晶物变化规律。利用电镜扫描绒毛上的结晶物,分析结晶物与绒毛的粘结形态。结果表明:在半管流条件下,随着时间的增长,植绒PVC管结晶量有先增大后逐渐稳定或者减小的趋势;普通PVC管基本上呈缓慢增加的趋势,且到某一阶段结晶量显著增加而到另外一阶段又显著减小,满管流条件下变化规律相似;对于普通PVC管而言,满管流情况下管道内壁越不容易附着结晶物;对于植绒PVC管而言,结晶物附着的难易程度与绒毛长度有着密切关系。可见植绒PVC管对隧道排水管除结晶有一定的作用,绒毛长度应根据排水管充水状态选取,以充分发挥绒毛除结晶的效果。     

寒热证大鼠舌体表面的扫描电镜观察

对雌性SPF级Wistar大鼠进行寒热证造模后,通过扫描电镜观察寒热证大鼠的舌体表面超微结构.结果显示:寒证组大鼠舌体表面丝状乳头密度较低、角质化程度较低,蕈状乳头角质化程度也较低;热证组大鼠舌体表面丝状乳头密度较高、角质化程度高,蕈状乳头角质化程度也较高.寒证大鼠舌质较光滑、舌苔较薄及热证大鼠舌质粗糙、舌苔较厚的实验结果与中医对寒热证舌象的描述一致.     

溶剂对TCNQ的红外和紫外-可见吸收光谱的影响

测量了7,7,8,8-四氰基对苯醌二甲烷(TCNQ)在5种溶剂中的红外和紫外-可见吸收光谱,用分子间相互作用的理论模型进行了分析,并通过建立LSER方程验证了频率变化是由于给体和受体配合所致.结果表明:TCNQ氰基的伸缩振动频率随溶剂电子受体数的增加而发生红移;吸收频率随溶剂极性参数ET(30)和ENT的增加而发生蓝移,并且ETN参数比ET(30)能更好地描述TCNQ的溶剂极性.     

不同电子供体对厌氧系统生物脱氮效率及微生物群落分布状态的影响

在厌氧条件下,分别以葡萄糖、甲醇和邻苯二甲酸氢钾作为电子供体对NO3--N进行厌氧反硝化实验,每种电子供体设定两个C/N比,分别为4∶1和10∶1.实验结果表明:在2种C/N比情况下,葡萄糖与甲醇作为电子供体时,总氮的去除速率一致,且都比邻苯二甲酸氢钾作为电子供体时要快.当C/N=4时,总氮的去除速率要快71%,而当C/N=10时,总氮的去除速率的差距只有7%.不同有机物作为反硝化的电子供体时,活性污泥样本中的微生物菌落检出情况表现出3个反应体系中具有各自优势的厌氧菌群、硝化及反硝化菌群明显特征.该微生物群落的分布特点反映出不同有机物作为电子供体时反应系统状态的差异性.     

重铬酸盐──三醋纤全息记录介质敏化液的最佳配制

本文通过实验研究了重铬酸盐──三醋酸纤维素酯全息记录新材料，敏化液中铬盐的用量，溶液的ｐＨ值及两种电子供体ＤＭＦ、ＤＭＳＯ对全息介质光敏性和全息图实时衍射效率的影响，实验结果表明，在敏化液中选择１５％的重铬酸铵，ｐＨ值取６．５以及电子供体的引入不仅提高了材料的感光记录速度，而且大大提高了全息图的实时衍射效率．