Synchrotron X-ray Diffraction Investigation of the Anomalous Behavior of Ice During Freezing of Aqueous Systems

Abstract

Simple aqueous systems, i.e., phosphate-glycine buffers and pure water, were studied at subambient temperatures by X-ray difractometry using a high-intensity synchrotron radiation source at the Advanced Photon Source of Argonne National Laboratory. Complex X-ray diffraction (XRD) patterns, with two or more poorly resolved peaks in place of each of the four diagnostic peaks of hexagonal ice, 100, 002, 101, and 102, referred as "splitting", were observed in the majority of cases. The splitting of up to 0.05 A (d-spacing) was detected for 100, 002, and 101 peaks, whereas 102 peak was less affected. Deformation of the lattice of hexagonal ice, probably due to local stress created on the ice/ice or ice/container interface during water-to-ice transformation, is proposed as a possible mechanism for the observed splitting of XRD peaks. Using molecular modeling, it was estimated that the observed shifts in the peak positions are equivalent to applying a hydrostatic pressure of 2-3 kbars. The splitting can be used to quantify stresses during freezing, which could improve our understanding of the role of water-to-ice transformation on the destabilization of proteins and other biological systems.

Freezing in sealed capillaries for preparation of frozen hydrated sections

“…They arise from spacings of 3.90, 3.67 and 3.44 Å, corresponding to the (100), (002) and (101) planes of hexagonal ice. Previously, calculations (based on hexagonal ice structure with unit cell axes a = b = 4.516 Å, c = 7.354 Å) reported in (Varshney et al , 2009) resulted in scattering spacings of 3.942, 3.715 and 3.482 Å. These calculations agree with our measurement within 1%; the difference may be because of slight miscalibration of the camera length.…”

The Journal of Microscopy would like to thank all those referees who reviewed papers for the Journal during 2011. Your assistance and contribution to the Journal is greatly appreciated.

“…They arise from spacings of 3.90, 3.67 and 3.44 Å, corresponding to the (100), (002) and (101) planes of hexagonal ice. Previously, calculations (based on hexagonal ice structure with unit cell axes a = b = 4.516 Å, c = 7.354 Å) reported in (Varshney et al , 2009) resulted in scattering spacings of 3.942, 3.715 and 3.482 Å. These calculations agree with our measurement within one percent; the difference may be due to slight miscalibration of the camera length.…”

Gold nanorings synthesized via a stress-driven collapse and etching mechanism

“…31,32 According to the method reported by Varshney et al, the stress value is~200 MPa. 33 In the current situation, the frame-like structure covered by a thin Au film may create an unusual stress because the thick frame may serve as a support to pin the deformation of the central Au layer. Therefore, the unique frame-like Au nanostructure is critical to the formation of Au nanorings by means of an unusual stress-driven structure collapse mechanism.…”