G1 beamline is hotter than it’s ever been before thanks to the undulator upgrade. Though the synchrotron is still operating at 120 ma , a little over half current, and some additional optics upgrades are expected this Summer, we’re already seeing 8 x 10^11 photons/s in our 250 um x 250 um beam. Don’t forget that here at CHESS we measure our beamline performance parameters carefully every run under realistic BioSAXS conditions so you can report accurate numbers in all your papers. You can always check the latest numbers at http://www.macchess.cornell.edu/MacCHESS/beamline_character.html
BioSAXS setup at G1.
The big news is that Jesse Hopkins has joined the MacCHESS team as the BioSAXS postdoc. Jesse comes to us from Rob’s Thorne’s physics group here at Cornell and is an experienced long-time user of G1 station. Those of you who have visited us for the Fall run will have noticed that Jesse has been quite busy already making improvements to both the RAW data processing software and to the robot control software. Thanks to Jesse, RAW now has special features just for inline size exclusion. SEC-SAXS is a powerful combination for solving difficult aggregation problems and separating mixtures. The runs are even easier to do than regular SAXS, but they require more sample, higher concentrations, and longer experiment times. We also now offer inline multi angle light scattering (MALS), dynamic light scattering (DLS), and refractive index detection (RI). For tough aggregation problems, the SEC-SAXS-MALS-RI-DLS combination is extremely powerful. Please check our information page on this topic if you think your problem would benefit from this technology: http://www.macchess.cornell.edu/MacCHESS/inline_SEC.html
Imagine a glass window only 5 microns thick! That’s 1/20th the thickness of a human hair. We’ve managed to routinely fabricate our sample cells from this material. Rigid, inert, and very low in parasitic scatter, it is nearly an ideal window material. The rigidity and long-term stability of the glass results in much more stable behavior of the smallest angle data over the course of data collection than was previously the case for our earlier plastic films.
Absolute Scale: in addition to calibrating your data collection runs using two protein standards, we are now also placing all measurements on an absolute scale (units of inverse centimeters). In addition to enabling better comparisons for neutron scattering and MALS data, this also gives an alternative way of cross-checking molecular weight. We’ll be adding an information page with example calculations to our web documentation shortly.
Biological Small-Angle X-Ray Solution Scattering (BioSAXS) at MacCHESS
MacCHESS supports a full-time BioSAXS beamline equipped
with state-of-the-art robotic sample loading, dual Pilatus-based SAXS/WAXS
detection, a full vacuum flight path with disposable sample
flow cell, temperature control, and automatic signal normalization.
How to apply for BioSAXS time
Users interested in trying BioSAXS may apply for time through the express-mode proposal mechanism. Visit: https://userdb.chess.cornell.edu/
BioSAXS Essentials 6 Workshop, May 2016,
YouTube, Web. 24 Aug. 2016.
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