Real-time swelling-series method improves the accuracy of lamellar neutron-diffraction data.
Neutron-diffraction data were collected from stacked bilayers of 1, 2-dioleoyl-sn-glycero-phosphocholine under conditions of increasing relative humidity at both 0 and 8.06% (2)H(2)O. Over the period of data collection, the d-repeat of both swelling-series samples increased. Each family of structure factors, representing each of the five orders of diffraction, are shown to lie on smooth curves, allowing structure factors of intermediate d-repeat to be determined. In the case of the 8.06% (2)H(2)O data, but not the 0% (2)H(2)O data, all observed structure factors lie on a single continuous transform. 8.06% (2)H(2)O has a net neutron-scattering density of zero; its use in neutron-diffraction experiments presents a novel application of the so-called 'minus fluid' approach, without mathematical manipulation. The data are used to demonstrate the increased accuracy inherent in this real-time swelling-series approach. A quantitative analysis of errors caused by differences in d--repeat in difference subtractions is presented.
Darkes
M J
MJ
Department of Preclinical Veterinary Sciences, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Summerhall, Edinburgh EH9 1QH, Scotland.
Bradshaw
J P
JP
D003461:Crystallography; D003627:Data Interpretation, Statistical; D017666:Deuterium Oxide; D008051:Lipid Bilayers / Q000737:chemistry*; D009502:Neutrons; D010713:Phosphatidylcholines / Q000737:chemistry
D008051:Lipid Bilayers; D010713:Phosphatidylcholines; C017251:1,2-oleoylphosphatidylcholine; D017666:Deuterium Oxide