1,721,557 research outputs found
Structure and fluctuations of highly oriented phospholipid membranes
No full textHighly oriented lipid membranes deposited on solid substrates offer unique experimental possibilities to study self-assembly phenomena, fluctuations, and interactions in lipid bilayer systems, both with and without additional membrane-active molecules such as amphiphilic peptides or membrane proteins. In diffraction experiments, the high orientation allows for a precise distinction between the normal q(z), and lateral component q(parallel to) of the scattering vector (q) over right arrow, opening up a way to study biologically relevant questions associated with the lateral structure of the bilayers. Modern sources and instruments for neutron and X-ray scattering, in particular the advent of third-generation synchrotron sources enable studies even of weakly scattering and weakly ordered systems. (C) 2000 Elsevier Science Ltd. All rights reserved
Dataset for H. Bruns et al. "Synapsin shields a lipid monolayer from interactions with vesicles and associated structural rearrangements", Biophysical Journal 2025
No full textPython Scripts for GID analysis of the data presented in
H. Bruns et al., Biophysical Journal 2025/202
Three-dimensional propagation in near-field tomographic X-ray phase retrieval
No full textThis paper presents an extension of phase retrieval algorithms for near-field X-ray (propagation) imaging to three dimensions, enhancing the quality of the reconstruction by exploiting previously unused three-dimensional consistency constraints. The approach is based on a novel three-dimensional propagator and is derived for the case of optically weak objects. It can be easily implemented in current phase retrieval architectures, is computationally efficient and reduces the need for restrictive prior assumptions, resulting in superior reconstruction quality
Observation of electron-induced characteristic x-ray and bremsstrahlung radiation from a waveguide cavity
No full textWe demonstrate x-ray generation based on direct emission of spontaneous x-rays into waveguide modes. Photons are generated by electron impact onto a structured anode target, which is formed as an x-ray waveguide or waveguide array. Both emission of characteristic radiation and bremsstrahlung are affected by the changes in mode density induced by the waveguide structure. We investigate how the excited modal pattern depends on the positions of the metal atoms and the distance of the focused electron beam with respect to the waveguide exit side. We compare the results to synchrotron-excited fluorescence. We then discuss how x-ray generation in waveguides can be used to increase the brilliance and directional emission of tabletop x-ray sources, with a corresponding increase in the spatial coherence. On the basis of the Purcell effect, we lastly show that the gain of emission into waveguide modes is governed by the quality factor of the waveguide
Propagation of X-rays in ultra-narrow slits
No full textWe study the propagation of X-rays in very narrow slits or waveguides. The onset of waveguiding effects is estimated analytically and quantified by finite-difference field calculations. A critical thickness is given below which waveguiding effects have to be taken into account. Finally, we consider the transmission of the smallest possible slits i.e. planar single-mode waveguides. (c) 2006 Elsevier B.V. All rights reserved
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