This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The development of instrumentation for an automated high throughput data collection system for solution x-ray scattering continues, combining a quartz capillary cell and a motorized sample changer, which combines a refrigerated aluminum block accepting any of the standard micro-plates or several PCR tube strips (up to total 8x12 tubes), with three motorized miniature linear translation stages whose vertical arm holds a syringe needle for sample aliquot selection and delivery. A Hamilton 560 fluid dispenser replaced Hamilton 540B to accommodate a larger number of fluid inlets and outlets required to accomplish sample cell cleaning, a newly automated feature. All above instrumentation are under Blu-ICE control. This year we adopted a completely new sample delivery scheme in which a syringe needle delivers a sample aliquot directly into a capillary cell instead of sending it via Teflon tubing. The new method substantially lowers the risk of generating air bubbles in the sample aliquot. A typical data collection sequence involves 1) the syringe needle picking up a sample aliquot on PCR tube strips, 2) the needle transferring the aliquot to the capillary cell, 3) repetitive translation of sample aliquot within the quartz capillary at around 1 microliter per second to minimize radiation damage, immediately followed by the initiation of a series of scattering data acquisition, 4) optional sample recovery to a PCR tube, 5) cleaning of the capillary and syringe needle by flushing them with 50% bleach and 50% ethanol solutions, then finally with distilled water;6) drying of the capillary and syringe needle by compressed air purging. The automated sequence eliminates manual sample change, and leads to more efficient use of beam time.
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