Acquisition of Diffraction Equipment for Interdisciplinary Research at Northwestern University

该提案要求提供资金，用于购置一台X射线衍射仪，安装在西北大学埃文斯顿校区的分析服务实验室，并为阿贡国家实验室高级光子源的大分子/小分子晶体学站购置数据收集设备。 这些仪器将极大地促进西北大学研究人员的研究和教学工作在两个非常基本的方式。首先，ASL X射线衍射仪将通过提供“电子胶片”的众多优点，包括显著减少数据收集时间，大大提高生产率。其次，APS设备将提供一种独特的工具，不仅用于快速收集大分子晶体的数据，还用于收集无机和有机材料微晶的数据。 使用我们现有的X射线衍射仪对各种无机和有机材料进行结构测定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数量。一个更严重的问题出现，由于我们的点探测器在密封管前面的信号噪声的固有限制。本提案中列出的主要用户都遇到了“困难”问题：只有非常小的晶体的可用性，超晶格/亚晶格的考虑，孪生晶体，漫散射，具有非常大的晶胞的晶体，以及对辐射敏感的晶体。使用当前的衍射仪，这些问题中的许多都没有解决。 配备1 K CCD或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晶体学需求的理想设计。随着这种仪器信噪比的提高，常规晶体的数据收集时间将大大缩短。这将大大改善大多数样品的周转时间，降低所涉费用，从而使更多用户能够利用该设施解决更广泛的问题。这对我们的学生尤其重要，他们将比现在更容易接触到现代X射线仪器。此外，大多数“困难”问题都可以通过这样一项文书得到解决。有些将保留，例如仅存在微晶，这些将在APS设施中解决。 APS设备也用于大分子晶体学。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）合作组建的合作访问团队运营的光束线的当前能力。目前，在DND-CAT束线上没有用于大分子晶体学的设施。拟议的二维数据收集仪器将安装在一个运动台上，该运动台将具有容纳CCD探测器的内置能力。操作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师提供一个真正独一无二的学习环境。来自埃文斯顿校区的化学系和生物化学、分子生物学和细胞生物学系以及芝加哥医学院校区的分子药理学和生物化学系的人员将与来自各个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.