Rheological Properties of Template Polymerization Polyacrylamide Aqueous Solutions

In this work, the aqueous solution rheology properties of both partially hydrolyzed polyacrylamide (HPAM) and the template copolymer (TPAM) synthesized from acrylic acid (AA) and acrylamide (AM) were investigated using an advanced rheometer and viscometer. The results were correlated with the corresponding molecular structures of HPAM and TPAM, which were characterized by high-resolution nuclear magnetic resonance. It was found that the thickening ability of TPAM is much stronger than that of HPAM due to its unique microblocky structure, while the viscosity of TPAM was more sensitive to shear rate. Furthermore, the effect of polymer concentration was also tested in an oscillation shear mode. It showed that the characteristic relaxation time of TPAM was much higher than that of HPAM at the high concentrations. The research on salt-resistance properties showed that the viscosity retention of TPAM was similar to HPAM at the same NaCl concentration. But, unexpectedly, at the same CaCl₂ concentration the viscosity retention of TPAM was much lower than that of HPAM, indicating a poor divalent salt-resistance property.     

Emergence of the sub‐THz central peak at phase transitions in artificial BaTiO3/(Ba,Sr)TiO3 superlattices

A prominent central peak in the sub‐THz frequency range was observed in the Raman spectra of BaTiO₃/(Ba,Sr)TiO₃ (BT/BST) superlattice grown on (001)MgO substrate. Both soft and central mode show an anomaly around 200 K and 280 K, which can be correlated with orthorhombic to monoclinic phase transition of BST and BT, respectively. The observed temperature dependence of the central mode enabled us to explain rather broad temperature dependence of the dielectric permittivity previously observed in BT/BST superlattices. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)     

LAMOST恒星分类模板间相似性度量分析

随着获取和收集天文光谱大数据能力的与日俱增,合理利用计算科学技术正确地分析海量光谱的处理方法及结果统计。前述工作采用了欧氏距离分析判别LAMOST实测光谱与模板之间相似度的研究,研究恒星分类准确性取决于高质量的模板光谱,选取LAMOST光谱在用的分类软件中183个恒星模板光谱,分别利用欧氏距离和马氏距离方法得出A,F,G,K和M型恒星模板间的均值和最大值,完成每条谱线相互之间的相关性分析,找出相对距离较大的模板及形成原因。相似度度量可视化实验数据结果表明模板之间具有一定的区分度,通过马氏距离分析模板间相似性能更进一步辨识出相近模板之间的细微差别,具备较优良的判别效果,证实了LAMOST现有分类的各模板间距离较均匀,且分类结果较为准确。该研究可进一步优化在用光谱分类模板,提升LAMOST恒星分类模板库的精确度和可信度。     

Collective motion of active particles in environmental noise

We study the collective motion of active particles in environmental noise, where the environmental noise is caused by noise particles randomly diffusing in two-dimensional space. We show that active particles in a noisy environment can self organize into three typical phases: polar liquid, band, and disordered gas states. In our model, the transition between band and disordered gas states is discontinuous. Giant number fluctuation is observed in the polar liquid phase. We also compare our results with the Vicsek model and show that the interaction with noise particles can stabilize the band state to very low noise condition. This band structure could recruit most of the active particles in the system, which greatly enhances the coherence of the system. Our findings of complex collective behaviors in environmental noise help us to understand how individuals modify their self-organization by environmental factors, which may further contribute to improving the design of collective migration and navigation strategies.     

有序银纳米线阵列的表面增强拉曼光谱研究

本文通过模板法制备了一系列不同孔径的氧化铝模板 ,并通过交流电向模板中沉积银而制成有序银纳米线阵列。以SCN- 作为探针分子 ,用H3PO4溶解模板并用共焦显微拉曼系统现场检测SERS信号。结果表明 ,SERS信号的强度随露出表面纳米线的长度的增加而变大 ,到一定程度后又逐渐减弱。这说明只有具有合适长径比的纳米线才会有最大的增强     

Tomographic analysis of the central magnetohydrodynamic oscillations on the HT-7 tokamak

Multi-channel soft x-ray (SX) detectors are applied to generate images of magnetohydrodynamic (MHD) oscillation on the HT-7 tokamak, and the data from SX cameras are analysed by using the Fourier--Bessel harmonic reconstruction method and the singular value decomposition. The image reconstruction of SX emissivity is obtained on the assumption of plasma rigid rotation. One of the important phenomena in the HT-7 discharge is the transition from the sawtooth oscillations to the MHD oscillations when the plasma density grows higher. The MHD structure observed in the SX tomography is featured as follows: the magnetic surface of MHD structure is made up of the crescent-shaped ``hot core' and the circular ``cold bubble'. The structure of the magnetic surface is relatively stable. It rotates in the direction of the electron diamagnetic drift at a frequency being the oscillation frequency of the MHD oscillations.     

DA-16晶体管毫伏表元件特性变异所致软故障分析

本文介绍了晶体元件特性参数变异所致软故障分析判断。     

液态泡沫结构及其稳定性

液态泡沫由大量气泡密集堆积在少量的表面活性剂溶液中形成, 是具有高度自组织结构的典型的软物质. 文章从泡沫物理学角度简要介绍了液态泡沫的结构特征和稳定性方面的研究.     

Study of nanocrystalline Fe－Al－N soft magnetic thin films

Fe－Al－N films were fabricated by reactive sputtering using a radio-frequency magnetron sputtering system. The effects of Al and N content and annealing temperature on microstructure and magnetic properties were investigated. The Fe－Al－N films, which have good soft magnetic properties, consist of nanocrystalline α-Fe grains and a small amount of other phases in the boundaries of α-Fe grains. The average α-Fe grain size is about 10－15nm. A slight amount of Fe－N and Al－N compounds precipitate in the boundaries of α-Fe grains and suppress their growth. Annealing improves the soft magnetic properties slightly by releasing the residual stress and reducing defects.     

单丝Z箍缩的一维单温辐射磁流体力学计算

 介绍在正弦电流波形下铝丝的内爆动力学过程的数值模拟计算，计算采用一维单温辐射磁流体力学模型，能流中除了常规热传导外，也包括黑体辐射流项，以考虑辐射对内爆动力学过程的影响。计算了用于箍缩预脉冲的低电流（幅值10～50 kA）和较高电流（幅值400 kA）情况下单丝的内爆结果。