This work describes the synthesis, analysis, and testing of the novel type of La/graphene composites as potential contrasting agents (CAs) for photon-counting computed tomography (PCCT). The impregnation of oxidized graphene nanoflakes (GNFs) with Lanthanum nitrate solution resulted in uniform distribution of La-containing particles on the flake surface with particle size of about 2–3 nm. La was confirmed to be a suitable contrasting element for PCCT that could be visualized in reference phantom media and in the presence of other CAs. Minimum concentration of La in the composites determined by PCCT was in the range of 2.5–5 mg⋅ml[Formula: see text].

The subject of the current research study is aimed at the development of novel types of contrast agents (CAs) for multi-energy computed tomography (CT) based on Ln–graphene composites, which include Ln (Ln = La, Nd, and Gd) nanoparticles with a size of 2–3 nm, acting as key contrasting elements, and graphene nanoflakes (GNFs) acting as the matrix. The synthesis and surface modifications of the GNFs and the properties of the new CAs are presented herein. The samples have had their characteristics determined using X-ray photoelectron spectroscopy, X-Ray diffraction, transmission electron microscopy, thermogravimetric analysis, and Raman spectroscopy. Multi-energy CT images of the La-, Nd-, and Gd-based CAs demonstrating their visualization and discriminative properties, as well as the possibility of a quantitative analysis, are presented.

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Results of an experimental investigation of the mechanism of hydrodynamic and heat processes interaction in turbulent separated flows on the basis of combined measurements of instantaneous local values of longitudinal skin friction vector component, wall heat flux and fluctuating wall pressure are presented. New combined wall probe was used in the experiments. The following cases of 2D separated flows are studied: a flow over a lug, a flow in the wake behind a transversal cylinder located near a wall. Data on space-time interaction of the measured parameters is obtained. It is shown that a mechanism of this interaction in many respects is determined by interaction of large scale coherent structures of a shear layer with a wall. In order to study the mechanism simultaneous measurements of the wall parameters and parameters in the wall region are provided. Also conditionally averaged fields of velocity and temperature in a flow are obtained as well as their correlation with the parameters distribution in a local wall region. A physical model of hydrodynamic and heat interaction of these structures with a wall is suggested.