利用霍尔效应测磁场实验的数据处理

推导了亥姆霍兹线圈产生磁场的全空间分布的普遍公式,讨论了如何确定磁感应强度的方向。就实验内容进行了实例分析,利用Matlab软件进行了相关计算,提出了利用霍尔效应测磁场实验的数据处理方法。最后,详细讨论了亥姆霍兹线圈所在平面处磁场强度相关参数的分布曲线。     

合肥光源逐束团测量系统研制

 逐束团测量装置属于宽带和实时测量,足以分辨重复频率为204 MHz的相邻束团的信号,设计功能包括横向水平和垂直Beta振荡,纵向同步相位振荡,束团填充等信息的实时检测。对信号频谱分析,系统参数设计,前端射频检测,锁相环信号合成,高速数据采集以及基于PXI的整个系统作了详细介绍,分析了若干调试和实验结果,并讨论了合肥光源储存环目前存在的不稳定性及该测试手段在诊断中的应用。     

板条射频放电产生单重态氧实验研究

 通过考察各种放电状态及气流条件下发生器内外物种的自发辐射谱,发现光谱峰值强度与对应物种浓度成正比。分析了主要的等离子体动力学过程,了解了单重态氧及其它物种的浓度变化规律。考察了α放电和γ放电两种不同的放电方式。发现在α放电状态下,体系中有较少氧原子等淬灭性粒子,更有利于O₂(¹Δ)产生。加入He,有效地降低了气体体系的离子化阈能和约化场强,约化场强最小时,产生的O₂(¹Δ)浓度最大,相较于纯氧放电,O₂(¹Δ)浓度提高一倍以上。考察了腔外各物种浓度的变化,O₂(¹Δ)离开放电腔后浓度稳定,沿距离减少较慢,有益于出光。优化了本系统的放电极间距,极间距太大或太小,都不利于单重态氧的产生。     

Vesicles Formed by Oligostyrene‐block‐Oligoaniline‐block‐Oligostyrene Triblock Oligomer

Novel π‐conjugated coil–rod–coil triblock oligomers containing optoelectronic active oligoaniline segments were synthesized. The block oligomer can self‐assemble into diverse aggregating morphologies including spherical micelles and thin‐layer vesicles in THF, which is found associated with the removing of the protecting groups of oligoaniline segments. A possible mechanism was proposed to explain the self‐assembly behavior changes in which chain conformation variation of the aniline segments initiated from deprotection of the nitrogen atoms is pointed to be the key factor that dominates the transition process.

     

Chain Sliding versus β-Sheet Formation upon Shearing Single α-Helical Coiled Coils

Coiled coils (CCs) are key building blocks of biogenic materials and determine their mechanical response to large deformations. Of particular interest is the observation that CC-based materials display a force-induced transition from α-helices to mechanically stronger β-sheets (αβT). Steered molecular dynamics simulations predict that this αβT requires a minimum, pulling speed-dependent CC length. Here, de novo designed CCs with a length between four to seven heptads are utilized to probe if the transition found in natural CCs can be mimicked with synthetic sequences. Using single-molecule force spectroscopy and molecular dynamics simulations, these CCs are mechanically loaded in shear geometry and their rupture forces and structural responses to the applied load are determined. Simulations at the highest pulling speed (0.01 nm ns⁻¹) show the appearance of β-sheet structures for the five- and six-heptad CCs and a concomitant increase in mechanical strength. The αβT is less probable at a lower pulling speed of 0.001 nm ns⁻¹ and is not observed in force spectroscopy experiments. For CCs loaded in shear geometry, the formation of β-sheets competes with interchain sliding. β-sheet formation is only possible in higher-order CC assemblies or in tensile-loading geometries where chain sliding and dissociation are prohibited.