HARDWARE FOR CHALLENGING SAMPLES

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。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 开发了一种新的数据采集形式，它利用MD2‘S x，y，z样品定心台的高精度和重复性，更好地利用大于光束尺寸的晶体，并将X射线损伤分布在大晶体的整个体积上。这是通过定义横跨样本的3空间扫描向量并作为数据收集过程的一部分沿着该向量扫描来实现的。可以在沿扫描向量的多个离散点(离散向量扫描)或沿扫描向量连续地采集完整或部分数据集，沿着在采集数据集中的每一帧之后断言的扫描向量的小步长(连续向量扫描)。我们表明，对于离散和连续的矢量扫描数据收集，辐射损伤对数据质量的影响通过在大于波束的样本体积上等分损伤来在很大程度上减轻。矢量扫描方法的改进被用来定位非均质晶体的最佳衍射区，或对准嵌入不透明冷冻、冷冻溶液中的样品。

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. A new form of data collection has been developed that exploits the high precision and reproducibility of the MD2's x,y,z sample centering stages to make better use of crystals larger than the beam size, and to distribute x-ray damage over the entire volume of large crystals. This is accomplished by defining a 3-space scanning vector that spans the sample and scanning along this vector as part of the data collection process. Complete or partial data sets may be acquired at a number of discrete points along the scanning vector (discrete vector scanning) or continuously along the scanning vector, with small steps along the scanning vector asserted after acquisition of each frame in a data set (continuous vector scanning). We show that for both discrete and continuous vector scanning data collection, radiation damage effects on data quality are largely mitigated by equipartitioning damage across the volume of samples larger than the beam. Modifications of vector scanning methods are used to locate optimally diffracting regions of a heterogeneous crystal or to align samples embedded in opaque frozen, cryosolution.