Epicocconone, A New Cell-Permeable Long Stokes' Shift Fluorescent Stain for Live Cell Imaging and Multiplexing

Epicocconone is a heterocyclic natural product from the fungus Epicoccum nigrum that fluoresces weakly in the green (520 nm). However, cells exposed to epicocconone rapidly absorb the dye and become bright orange fluorescent because the natural product reacts reversibly with proteins. The orange fluorescence is enhanced in lipophilic environments, allowing the visualization of membranous organelles and lipid rafts but does not stain oligonucleotides. As the unconjugated dye has no orange fluorescence, there is no need to wash out the excess fluorophore. Epicocconone is a neutral, non-toxic, small molecule that appears to diffuse readily into live of fixed cells without the need for permeabilization. These features enable the real-time imaging of live cells and the study of organelle movements. Cells stained with epicocconone are excitable by common lasers (UV, 405, 488, and 532 nm) and its long Stokes' shift allows multiplexing applications with more common short Stokes' fluorophores using a single light source.     

共焦腔增强的空气拉曼散射

拉曼光谱是一种无损、快速的物质成分分析和检测方法.由于拉曼信号强度微弱,使得拉曼光谱的检测应用受到极大的限制.针对增强拉曼散射信号强度、提高检测灵敏度这一问题,设计了一种用于自发拉曼散射信号增强的共焦腔样品池,开展了基于该共焦腔的空气拉曼散射信号增强研究.共焦腔的腔镜反射率为92%,这一设计在保证共焦腔通带宽度与激光器线宽匹配的同时能有效地降低共振调节难度.实验中采用0°探测构型收集拉曼信号,并由成像式拉曼光谱仪获取光谱信号.实验发现,在共振状态下,共焦腔的耦合效率达到87.5%,单向激光功率实现约11倍放大;与无共振腔相比,共焦腔对拉曼信号实现17倍放大,信噪比提高2倍.此外,空气中CO_2的3σ检测限达到200 ppm量级.结果表明,该系统对自发拉曼散射信号增强效果显著,并且有较高的检测灵敏度.     

Detect early stage lung cancer by a LAMP microfluidic chip system with a real-time fluorescent filter processor

This work presents a promising clinical molecular diagnostics for early stage lung cancer. This novel diagnostic method utilized the loop-mediated isothermal amplification (LAMP), microfluidic chips and a confocal optical detector with a non-linear fluorescent filter processor. An isothermal amplification based microfluidic chip for the early diagnostics of lung cancer was developed and a confocal optical detector was improved by a novel real-time fluorescent filter to sensitively monitor the DNA amplification procedure with high signal to noise ratio and fluorescence collecting ability. Experiment showed that a rapid diagnostic of lung cancer by detecting the existence of the CEA mRNA could be performed in only 5 μL of reaction assay in less than 45 min. While the traditional in-tube RT-PCR set consumed more than 25 μL of the assay and took more than 90 min.     

共焦波导结构回旋行波管的设计与仿真

针对0.14 THz大气窗口,利用CST微波工作室和3维粒子模拟软件,对共焦波导结构的太赫兹回旋行波管进行了冷腔色散和注波互作用的模拟研究。以TE06模式作为互作用工作模式,在电压为35 kV、电流为2 A、横纵速度比为0.85的电子束参数下,当输入信号为1 W时,得到最高2 kW的微波功率输出,3 dB带宽为3.5 GHz,增益为30 dB。     

0.4 THz回旋行波管的设计与模拟

利用三维粒子模拟仿真软件,对共焦波导结构的0.4 THz回旋行波管进行了注波互作用的模拟研究。以共焦波导的冷腔色散以及衍射损耗入手,最终选定HE06模作为互作用工作模式。为了对寄生振荡进行抑制,在互作用结构中引入了截断。在模拟过程中,通过调节束压、束流、工作磁场、电子束横纵速度比,得到了最优的工作参数。最终,在束压34 kV、磁场14.25、束流2 A、横纵速度比0.75的工作参数下,当输入信号为1 W时,得到了最高2.76 kW的功率输出,增益超过34 dB,3 dB带宽为8 GHz,效率达到4%。     

共焦拉曼光谱对疏水基底上Mg(CH3COO)2液滴与CO2非均相反应动力学过程的观测

本文利用共焦拉曼光谱在球形液滴的表面和中心可聚焦两次的特性, 观测了不同RH(relative humidity, 相对湿度)下疏水基底上Mg(CH3COO)2液滴与CO2在液滴表面和中心的反应情况。结果表明, 反应生成的产物为碱式碳酸镁。当RH约73%时, 液滴表面和中心生成的产物的量差别不大; 当RH约65%时, 表面和中心的差别较RH约73%时明显; 而当RH降至约58%时, 表面和中心的差别则变得非常明显。由于Mg(CH3COO)2液滴在较低相对湿度下会形成胶态结构, 引起传质受阻, 从而使得CO2由液滴表面扩散到内部变得越来越困难, 最终导致液滴表面生成的产物比中心多。     

Fiber-optic Based Scanning Confocal Microscopic Interferometer for the Measurement of Surface Topography

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Raman microspectroscopic mapping or thermal system used to investigate milling‐induced solid‐state conversion of famotidine polymorphs

Confocal Raman microspectroscopy was used to nondestructively determine the polymorphic conversion of famotidine in the course of the milling process. A mapping system was applied to assess the blending uniformity of each polymorphic component in the milled mixture. Raman microspectroscopy combined with a thermal analyzer was also used to investigate the synergistic co‐effects of milling and heating on the polymorphic conversion of famotidine polymorphs. Famotidine has two polymorphs, forms A and B, the raw material of famotidine used was proved to be of form B. The Raman peak intensity ratio of the 2920 cm⁻¹ band for form A and 2897 cm⁻¹ band for form B was used to act as an indicator to evaluate the polymorphic conversion of famotidine form B to form A after different milling courses. The results indicate that the peak intensity at 2897 cm⁻¹ gradually decreased with the milling time, whereas the peak intensity at 2920 cm⁻¹ slowly enlarged, suggesting the polymorphic conversion of famotidine from form B to form A. The longer milling process might strongly induce and promote this polymorphic conversion of famotidine. Both polymorphic forms of famotidine were found to be well uniformly distributed within the milled samples due to their smaller varieties by using the Raman microscopic mapping system. The temperature effect could synergistically accelerate the polymorphic conversion of famotidine from form B to form A in the milled sample. The thermal‐dependent critical temperature for sharply enhancing the content of famotidine form A in each milled sample was also identified. Copyright © 2007 John Wiley & Sons, Ltd.     

强激光腔镜温升对腔几何参数和远场光强的影响

 利用交替方向隐式有限差分法分析了高能激光器虚共焦非稳腔反射镜的温度场及热变形的数值计算方法。以单晶硅为例,计算了反射镜由于吸收激光能量而形成的温度场分布以及由此引起的热变形对谐振腔几何结构参数的影响,并在此基础上数值模拟了热畸变情况下正支虚共焦非稳腔的远场光强分布。计算结果表明:在激光束辐照的开始阶段,温升场主要集中在激光束辐照的中心区域内,在整个镜面上远未拉平,由此引起的厚度方向温升分布也是如此,很不均匀。