DEVELOPMENT OF MICRO-WAXS AND MICRO-SAXS SET-UP

这个子项目是利用资源的许多研究子项目之一 由NIH/NCRR资助的中心拨款提供。次级项目的主要支助 子项目的主要研究者可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 表示子项目使用的中心基础设施的估计数量， NCRR赠款不直接向子项目或子项目工作人员提供资金。 BiOCAT项目核心项目2的目标2是时间分辨率小角度X射线散射。微流体技术与小角X射线散射的结合使用允许探测微秒时间尺度。为了使这些技术发挥作用，X射线束的尺寸必须小于流体路径，以减少背景并收集良好的数据质量。在这里，我们评估了微WAXS实验的微探针光学的使用。将二极管安装在直径为2.8mm的光束光阑上以记录透射。样品检测器距离为280 mm。光束聚焦在探测器上。将8 mg/ml折叠的细胞色素C溶液加载到流动池上。获得了与文献一致的Rg值的良好质量的散射数据。计划对设置进行的改进包括将KB镜向上游移动，以增加样品到检测器的距离，从而获得更小的Q值。我们还将X射线束聚焦到检测器和样品之间的一个点，以减小样品处的光束尺寸，并沿毛细管沿着实现更好的空间分辨率以及更好的反应时间分辨率。我们还将测试一种新的微流体混合器。计划在11月下旬进行调试试验，并计划在12月收集细胞色素C折叠时间分辨研究的数据。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Aim2 of Core Project 2 for the BiOCAT project is Time Resolution Small-Angle X-ray Scattering. The combined use of microfluidics technique with Small-Angle X-ray Scattering allows probing microsecond timescales. For these techniques to work, the X-ray beam size has to be smaller than the fluid path to reduce the background and collect good data quality. Here we evaluated the use of the microprobe optics for micro-WAXS experiments. A diode was installed on a 2.8mm diameter beam stop to record transmission. The sample detector distance was 280mm. The beam was focused on the detector. 8mg/ml folded cytochrome C solution was loaded on the flow cell. Good quality scattering data were obtained with Rg values in agreement with the literature. Planned improvements to the setup include moving the KB mirrors upstream to increase the sample to detector distance to access smaller Q values. We will also focus the X-ray beam to a spot between the detector and the sample to decrease the beam size at the sample and achieve a better spatial resolution along the capillary as well as better temporal resolution of the reaction. We will also \test a new microfluidic mixer. Commisioning tests are planned for late Novemerb with data collection for time resolved studies of folding of cytochrome C are planned for December.