Acquisition of Diffraction Equipment for Interdisciplinary Research at Northwestern University

该提案要求提供经费，用于购置西北大学埃文斯顿校区分析服务实验室的一台X射线衍射仪，以及阿贡国家实验室高级光子源的大分子/小分子结晶学站的数据收集设备。这些仪器将在两个非常基本的方面极大地促进西北大学研究人员的研究和教学工作。首先，ASL X射线衍射仪将提供“电子胶片”的众多优势，包括显著减少数据收集时间，从而极大地提高生产率。第二，APS设备将提供一个独特的工具，不仅用于从大分子晶体中快速收集数据，而且还用于从无机和有机材料的微晶体中收集数据。使用我们目前的X射线衍射仪测定各种无机和有机材料的结构通常需要几天到几周的数据收集，这限制了可以分析的结构的数量。由于我们密封管前面的点探测器在信噪比方面的固有限制，出现了一个更严重的问题。该提案中列出的主要用户都遇到了“困难”问题：仅有非常小的晶体可用、超晶格/次晶格考虑、孪生晶体、漫射散射、具有非常大晶胞的晶体以及对辐射敏感的晶体。用目前的衍射仪，这些问题中的许多都没有得到解决。配备LK CCD或图像板面积探测器和旋转阳极发生器的X射线衍射仪是满足主要用户的结晶学需求的理想设计。随着这种仪器提供的信噪比增加，常规晶体的数据收集时间将大大减少。这将大大缩短大多数样品的周转时间，降低相关成本，从而使该设施可供更多用户使用，解决更广泛的问题。这对我们的学生尤其重要，他们将比现在有更多的机会接触到现代X射线仪器。此外，大多数“困难”问题都可以在这样一个工具上得到解决。有些将继续存在，例如只存在微晶体，这些问题将在APS设施中解决。APS设备也用于大分子结晶学。所要求的CCD探测器将增强和升级由西北大学与杜邦公司和陶氏化学公司(DND-CAT)合作组成的协作访问小组运营的光束线的当前能力。目前，在DND-CAT束流线上还没有大分子结晶学的设施。拟议的二维数据收集仪器将安装在一个运动台上，该工作台将具有内置能力，以容纳一个电荷耦合器件探测器。运行探测器和现场处理数据所需的计算机硬件也是拟议设施的一部分。事实上，这些配套设施将为学生和教职员工提供一个真正独一无二的学习环境。来自埃文斯顿校区化学系和生物化学、分子生物学和细胞生物学系以及芝加哥医学院校区分子药理和生物化学系的人员将与来自不同领域的学术和工业科学家进行互动。

This proposal requests funds for the acquisition of an X-ray diffractometer to be located in the Analytical Services Laboratory (ASL) at the Evanston Campus of Northwestern University and for data collection equipment for the macromolecular/small molecule crystallography station at the Advanced Photon Source (APS) at Argonne National Laboratory. These instruments will greatly facilitate the research and teaching efforts of Northwestern University researchers in two very basic ways. First, the ASL X-ray diffractometer will greatly improve productivity by providing the numerous advantages of "electronic film", including significant reduction in data collection times. Second, the APS equipment will provide a unique tool not only for the rapid collection of data from macromolecular crystals but also for the collection of data from microcrystals of inorganic and organic materials. Structure determinations of a wide range of inorganic and organic materials with the use of our present X-ray diffractometers typically require several days to several weeks for data collection, limiting the number of structures that can be analyzed. A more severe problem arises owing to the inherent limitations in signal-to-noise of our point detectors in front of sealed tubes. The major users listed in this proposal all encounter "difficult" problems: the availability of only very small crystals, superlattice/sublattice considerations, twinned crystals, diffuse scattering, crystals with very large unit cells, and crystals that are sensitive to radiation. With the current diffractometers many of these problems are not resolved. An X-ray diffractometer equipped with a lK CCD or image-plate area detector and a rotating anode generator is ideally designed to address the crystallographic needs of the major users. With the increased signal-to-noise available from such an instrument, data collection times for routine crystals will be greatly reduced. This will significa ntly improve turn-around time for most samples, will reduce the costs involved, and hence will make the facility available for a wider range of problems to a larger number of users. This is especially important to our students, who will have far greater access to modern X-ray instrumentation than they do at present. In addition, most of the "difficult" problems will be amenable to solution on such an instrument. Some will remain, for example the existence of only microcrystals, and these will be addressed at the APS facility. The APS facility is also used for macromolecular crystallography. The requested CCD detector will enhance and upgrade the current capabilities of the beam line operated by the Collaborative Access Team formed by Northwestern University in collaboration with DuPont de Nemours & Co. and The Dow Chemical Co. (DND-CAT). At present, there are no facilities for macromolecular crystallography at the DND-CAT beam line. The proposed two-dimensional data collection instrument will be mounted on a kinematic table that will have built-in capabilities to accommodate a CCD detector. The necessary computer hardware to operate the detector and to process data on-site are also part of the proposed facility. Indeed, these complementary facilities will provide a truly one-of-kind learning environment for both students and faculty. Personnel from the Department of Chemistry and the Department of Biochemistry, Molecular Biology, and Cell Biology on the Evanston Campus and the Department of Molecular Pharmacology and Biological Chemistry of the Medical School Campus in Chicago will interact with both academic and industrial scientists from a variety of fields.