We report on the design and experimental realization of a 2D x-ray grating interferometer. We describe how this interferometer has been practically implemented, discuss its performance, and present multidirectional scattering (dark-field) maps and quantitative phase images that have been retrieved using this device. 相似文献
The layer‐by‐layer (LBL) assembly of poly(diallyldimethylammonium chloride) and poly(sodium styrene sulfonate) on poly(sulfo propyl methacrylate) brushes resulted in films with nanometer‐ and micrometer‐sized holes and ledges, observed by atomic force microscopy and scanning electron microscopy. Polyelectrolyte assembly was followed by the quartz microbalance technique. The formation of ledges and holes is explained by the interaction of the brush polymers with the incoming polyelectrolytes during the LBL assembly, inducing a spatially localized and self‐organized accumulation of the assembled polymers.
We report numerical and experimental results demonstrating accurate region-of-interest computed tomography (CT) reconstruction based on differential phase-contrast projection (DPC) images. The approach removes the constraint of covering the entire sample within the field of view of the image detector. Particularly for biomedical applications, the presented DPC-CT region-of-interest approach will allow for the visualization of previously inaccessible details deep inside an entire animal or organ. We envisage that this development will also be of interest for potential future clinical applications, because grating-based DPC-CT can be implemented with standard x-ray tube sources. 相似文献
A commercial electron spin analyser, based on spin-polarised low-energy electron diffraction (SPLEED) from W(1 0 0), has been characterised with incident polarised electron beams from a standard GaAs polarised electron source. The dependence of the Sherman function on the scattering energy and elapse time after CO-flash of the tungsten crystal of the analyser have been measured. The influence of the stray magnetic field on the performance of the analyser has been investigated. The spin analyser has been applied in monitoring the reorientation transition of the easy magnetisation direction of Fe films on W(1 1 0) upon the exposure of CO adsorbent on the surface. 相似文献
In order to investigate control of voice fundamental frequency (F0) in speaking and singing, 24 adults had to utter the nonsense word ['ta:tatas] repeatedly, while in selected trials their auditory feedback was frequency-shifted by 100 cents downwards. In the speaking condition the target speech rate and prosodic pattern were indicated by a rhythmic sequence made of white noise. In the singing condition the sequence consisted of piano notes, and subjects were instructed to match the pitch of the notes. In both conditions a response in voice F0 begins with a latency of about 150 ms. As predicted, response magnitude is greater in the singing condition (66 cents) than in the speaking condition (47 cents). Furthermore the singing condition seems to prolong the after-effect which is a continuation of the response in trials after the frequency shift. In the singing condition, response magnitude and the ability to match the target F0 correlate significantly. Results support the view that in speaking voice F0 is monitored mainly supra-segmentally and controlled less tightly than in singing. 相似文献
