Melting of heterogeneous vortex matter: The vortex ‘nanoliquid’

Disorder and porosity are parameters that strongly influence the physical behavior of materials, including their mechanical, electrical, magnetic and optical properties. Vortices in superconductors can provide important insight into the effects of disorder because their size is comparable to characteristic sizes of nanofabricated structures. Here we present experimental evidence for a novel form of vortex matter that consists of inter-connected nanodroplets of vortex liquid caged in the pores of a solid vortex structure, like a liquid permeated into a nanoporous solid skeleton. Our nanoporous skeleton is formed by vortices pinned by correlated disorder created by high-energy heavy ion irradiation. By sweeping the applied magnetic field, the number of vortices in the nanodroplets is varied continuously from a few to several hundred. Upon cooling, the caged nanodroplets freeze into ordered nanocrystals through either a first-order or a continuous transition, whereas at high temperatures a uniform liquid phase is formed upon delocalization-induced melting of the solid skeleton. This new vortex nanoliquid displays unique properties and symmetries that are distinct from both solid and liquid phases.     

核磁共振成像一维空间编码教学实验

利用梯度磁场实现检测信号的空间编码,是核磁共振成像(MRI)的关键技术.本文采用ccc系列样品将二维问题简化为一维,使用超小型教学用核磁共振成像仪进行了一维空间编码实验研究,并对实验过程及实验结果进行了计算模拟和分析.     

0.86μm激光扫描二维成像的实验研究

本文给出作者设计的0.86μm激光二维成像系统的原理框图、成像雷达距离方程和部分物体对0.86μm激光的反射对比度的测试数据,并展示了各类物体激光成像的照片.     

用离子速度影象技术研究n-C4H9Br的光解

利用离子速度影象技术研究了正一溴丁烷(n-C4H9Br)在231~267 nm波段的光解,得出了如下结论:正一溴丁烷(n-C4H9Br)在231~267 nm波段的吸收源于基态到三个最低激发态的跃迁,这三个激发态标识为1A″、2A′和3A′;发生在这三个排斥态的势能面(PES)上的光解最终导致C4H9 Br(2P3/2)或C4H9 Br*(2P1/2)的产生;2A′和3A′态之间存在避免交叉(Avoided crossing)会影响最终的光解产物;从基态1A′到激发态1A″的跃迁矩垂直于对称面,也就垂直于C-Br键;从基态1A′到激发态3A′的跃迁矩平行于对称面,同时平行于C-Br键;从基态1A′到激发态2A′的跃迁矩在对称面内,且与C-Br键成53.1°夹角.我们也讨论了正一溴丁烷(n-C4H9Br)在234 nm和267 nm附近光解时的避免交叉几率(Avoided crossingprobability),以及它对单通道相对产额(Relative fraction of the individual pathways)的影响.     

红外动态图像生成技术概念研究

红外动态图像生成技术的基本概念包括基本术语及其定义。为了描述红外动态图像生成技术的特性,通常采用如光源类型、光谱波段、阵列规模、空间分辨率、填充因子、时间常数、帧频、闪烁、温度范围、串扰、均匀性、发射率、辐射对比度、动态范围、温度分辨率、调制传递函数、几何畸变及最大温度和最大辐射强度等概念。介绍了描述红外动态图像生成系统性能的基本概念的定义。转换器的指标定义对于转换器的设计和性能指标的测试都有重要的意义。     

“阳”加速器钼丝X-pinch初步实验研究

 在“阳”加速器上进行了直径分别为10, 15, 20 μm, 交叉角为32°,45°,60°的钼（Mo）丝X-pinch实验。“阳”加速器产生的电流峰值约520 kA，上升时间80 ns。实验中通过X射线功率谱仪和纳秒分幅相机等仪器对Mo丝X-pinch辐射特性进行了诊断。实验表明：Mo丝X-pinch过程中会出现多次X射线爆发，箍缩过程中产生的热点辐射出能量超过3 keV的X射线，探测到的最小热点直径小于30 μm。     

光学三维成像实验系统

建立光学投影层析三维成像系统,该系统包括光学成像、图像采集、断层重建及三维显示,重建算法为滤波反投影算法.实验结果表明:利用该系统得到的重建图像与样品的形状吻合,重建结果边缘清晰,伪迹较小.     

荧光波长对共焦显微镜成像特性的影响

导出了共焦显微镜中不同荧光波长情况下的荧光功率传输函数、三维脉冲响应函数（3D－PSF）和三维光学传递函数（3D－OTF）。结果表明，不同的荧光波长对共焦显微镜的空间截止频率、分辨率、光学传递函数存在明显的影响。当激发波长与荧光波长的比值下降到一定程度时，可以看到明显的失锥现象。     

Near-field thermoelastic imaging coupled with infrared detection

Near-field thermoelastic imaging is a simple way to investigate the thermal and coupled thermoelastic properties of materials. A few microscopes, deriving from the atomic force microscope, have been used to observe and to quantify the samples observed. But the main problem is the absolute measurement of the temperature, because surface topography and thermal expansion contributions are not easily discernible. In the proposed SThEM (scanning thermoelastic microscope), the tip is excited at the resonance frequency of the cantilever and the sample is periodically heated by the Joule effect. Thus the static contributions (drift, topography) are reduced. Moreover, a radiometric sensor, operating in the far field, has been added in order to quantify the temperature. This multi-acquisition microscope enables one to investigate small objects at the nanoscale with complementary information at the micrometric scale.     

Neuropeptide imaging on an LTQ with vMALDI source: The complete ‘all-in-one’ peptidome analysis

Direct tissue imaging was performed on dissected insect tissue using a MALDI ion trap to visualize endogenous neuropeptides. Coupling tissue imaging to tandem MSⁿ allows for the identification of previously known species and the ability to identify new ones by de novo sequencing, as searchable databases for insects are sparse. Direct tissue imaging is an attractive technique for the study of neuropeptides as minimal sample preparation is required prior to mass spectrometry. We successfully identified neuropeptides present in the corpora cardiaca and allata of Acheta domesticus (the house cricket). Diagnostic fragments at low m/z were used to distinguish between lipids and neuropeptides. The distribution of peptides appears to be more differentially localized than that of phospholipids, which seem to be more evenly distributed within the tissue.