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![[Figure 5]](hi2028fig5mag.jpg)
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Figure 5
(a) Typical powder diffraction pattern for hydrated DPPC in the Lβ′ phase recorded at 75% w/w water and 295 K (CHESS, A1 station, 6.3 mA, 5.2 GeV, 10 min exposure). (b) X-ray-induced changes in the mesophase structure of fully hydrated DPPC. Low- and wide-angle diffraction from the lipid recorded on X-ray-sensitive film is shown as a series of consecutive X-ray photographs (exposure time 30 s) recorded during continuous X-irradiation of the sample. Measurements were performed at 298 K in the Lβ′ phase using focused monochromatic X-rays at 1.56 Å (8 keV) on the A1 station at CHESS. The incident flux on the sample was 1.7 × 1010 photons s−1 (18 krad s−1). Each frame corresponds to a dose of 0.54 Mrad such that 150 s represents a total accumulated dose of 2.7 Mrad. The sample-to-detector distance was 11 cm, and sequential patterns were recorded in 1.0 cm-wide strips on a 12.5 × 17.5 cm Kodak DEF-5 X-ray-sensitive film. Elapsed times are indicated. (c) Changes in the low-angle diffraction pattern of the Lβ′ phase of hydrated DPPC (50% w/w water) at 298 K induced by X-irradiation. After irradiation, diffuse scattering appears in the diffraction patterns, most prominently between the (001) and (002) reflections. Diffraction peaks and diffuse scattering are oriented in the 1 o'clock to 7 o'clock direction before and after exposure. Images before (left) and after (right) irradiation are shown. Experimental conditions include ESRF beamline ID2, 12.5 keV, 6.3 × 1011 photons s−1, 490 krad s−1, total accumulated dose of 59 Mrad. (b) is modified from Fig. 3 of Cheng & Caffrey (1996  ) and (c) is modified from Fig. 1 of Cherezov et al. (2000). |
![[Figure 5]](hi2028fig5.jpg)
 | JOURNAL OF SYNCHROTRON RADIATION |
ISSN: 1600-5775
