Fig 1.
A 2-dimensional X-ray intensity map recorded on a stack of POPC bilayers. Measurements were performed 100% RH. The most intense scattering is specular (q‖ = 0) with additional diffuse off-specular scattering that originates from out-of-plane membrane fluctuations. B Intensity profile of A along the out-of-plane scattering vector q‖ at qz=3q1 and 3.5q1, where q1 refers to the 1st order lamellar peak. C 2-dimensional map of Eq 4. D Simulated line-cuts of C at qz=3q1 and 3.5q1.
Fig 2.
A) Flow diagram of the reduction routine (written in Python). B Flow diagram of the fitting program (written in C++ and CUDA). Critical subroutines are highlighted in light blue and light green, and are visualized in greater detail in Fig 4.
Fig 3.
Most 2-dimensional flat detectors subtend the spherical coordinate system of the reciprocal space spanned by the angle θ.
Fig 4.
Flow diagram of the subroutines.
The program pre-calculates arrays of the height-height pair correlation function δun(r) and the finite size effect functions (Eqs 4 and 5) before calculating a single q‖ profile for given values of qz, q‖, ξ, η and q1.
Fig 5.
Screenshots of the reduction tab GUI: A Reduction-specific and Instrument-specific parameters can be entered by the user. B The progress of the reduction is visualized in a text-field and progress-bar. Once complete, the program visualizes the 2-dimensional intensity maps, the reflectivity profile as well as the q‖ line cuts (source: https://medusa.genapp.rocks/medusa/).
Table 1.
A summary and description of the input parameter.
Fig 6.
Screenshots of the fitting tab GUI: A Fitting-specific parameters can be entered by the user. B The progress of the fitting is visualized in a text-field reporting the log-output from the GPU-accelerated program. The determined bending rigidity Kc, the interaction modulus B as well as χ2 are updated for every iteration. Once complete, the program visualizes the q‖ line cuts with the respective best-fit line and provides a download link to the reduced and fitted data (source: https://medusa.genapp.rocks/medusa/).
Fig 7.
The setup of the X-ray diffraction machine is schematically sketched.
The central components: X-ray tube, collimator optics, humidity chamber and detector are marked in the graphics.