Rounded concentric structures

As an overview of rounded concentric structures, it can be said that they have been detected as wholly carbon nanoparticles like onions, with and without a hole in the center, or a kernel of other material inside. They are the consequence of successive elimination of pair of carbon atoms from... 

Schraub, F. A., R. L. Simpson, and E. Janssen, 1969, Two-Phase Flow and Heat Transfer in Multirod Geometries Air-Water Flow Structure Data for a Round Tube, Concentric Eccentric Annulus, and Nine-Rod Bundle, GEAP-5739, General Electric Co., San Jose, CA. (5)... 

A. From the main road leading from the entrance to the concentration camp, I saw a curious small, rounded, hut-like structure. Since it looked very peculiar, I asked what it was. I was told that it served to cremate the corpses in the case of deaths that had arisen. 

It is usually necessary to match the refractive indices of two fluids (and the transparent wall of flow passage in some cases particularly for microchannel flow). For example, in an experimental study on the selfpreserving structure of steady round buoyant turbulent plums in cross flow (Diez et al., 2005), planar-LIF (PLIF) and PIV techniques are utilized to measure the mean concentration of source fluid and mean velocity fields simultaneously. Both PLIF and PIV measurements in this study necessitate matching the indices of refraction of the source (water solution of potassium phosphate, monobasic KH2PO4, containing Rhodamine 6G dye) and ambient fluids (ethyl alcohol/water) to avoid scattering the laser beam away from the buoyant flow. Visual inspection... 

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