“…From the basic properties of Brownian diffusion, the particles should be of sub micrometer sizes (nanoparticles), and the capillaries should be narrow (less than one millimeter), and these conditions complicate the practical realization of the above solved mathematical problems. Nevertheless, the practical realization of the point or, rather, the segment pulse emission at the inlet line, and the point (segment) detection of local concentrations at the outlet line are very difficult but feasible technical problems [12][13][14][15]. In particular, the mathematical solutions to the point and segment sources producing the particles in either the single pulse or pulse periodic operating mode would be of importance, e.g., in laser photochemistry.…”