Iron-Catalyzed Tandem Cyclization and Cross-Coupling Reactions of Iodoalkanes and Aryl Grignard Reagents. -The reaction is assumed to proceed via a radical process. In the case of substituted alkenes (XV) and (XVII) an internal cyclization precedes the cross-coupling pathway, presumably due to the steric congestion. -(KIM, J. G.; SON, Y. H.; SEO, J. W.; KANG*, E. J.; Eur.

BackgroundIn sparse-view CT imaging, strong streak artifacts may appear around bony structures and they often compromise the image readability. Compressed sensing (CS) or total variation (TV) minimization-based image reconstruction method has reduced the streak artifacts to a great extent, but, sparse-view CT imaging still suffers from residual streak artifacts. We introduce a new bone-induced streak artifact reduction method in the CS-based image reconstruction.MethodsWe firstly identify the high-intensity bony regions from the image reconstructed by the filtered backprojection (FBP) method, and we calculate the sinogram stemming from the bony regions only. Then, we subtract the calculated sinogram, which stands for the bony regions, from the measured sinogram before performing the CS-based image reconstruction. The image reconstructed from the subtracted sinogram will stand for the soft tissues with little streak artifacts on it. To restore the original image intensity in the bony regions, we add the bony region image, which has been identified from the FBP image, to the soft tissue image to form a combined image. Then, we perform the CS-based image reconstruction again on the measured sinogram using the combined image as the initial condition of the iteration. For experimental validation of the proposed method, we take images of a contrast phantom and a rat using a micro-CT and we evaluate the reconstructed images based on two figures of merit, relative mean square error and total variation caused by the streak artifacts.ResultsThe images reconstructed by the proposed method have been found to have smaller streak artifacts than the ones reconstructed by the original CS-based method when visually inspected. The quantitative image evaluation studies have also shown that the proposed method outperforms the conventional CS-based method.ConclusionsThe proposed method can effectively suppress streak artifacts stemming from bony structures in sparse-view CT imaging.

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A chemoselective reductive cyclization and cyclomethylation reaction of 7‐iodohept‐2‐yne and 7‐iodohepta‐1,2‐diene derivatives has been carried out using an iron catalyst and various alkyl Grignard reagents, resulting in the formation of pyrrolidines, tetrahydrofurans, and carbocycles with an alkene functional group. The reaction is initiated by single‐electron transfer from reduced Fe species to alkyl iodides and the resulting Fe−H or Fe−Me compound differentiated the structures of the cyclized products, which exhibited diverse complexities and synthetic utilities.

We developed a carbon nanotube field emission x-ray system for computed tomography imaging. The obtained x-ray images were reconstructed to tomography image using back projection and filtered back projection algorithm. The resulting reconstructed x-ray image clearly shows micrometer scale.