Analysis of disk characteristics in the vicinity of the spiral arm in model 1 at t = 90 kyr. The analyzed element of the arm is outlined with the black dashed line in the upper-left panel. The other smaller panels show the Stokes number St, volume density of gas ρ_g, gas temperature in the midplane T_mp, ratio of the maximum dust size to fragmentation barrier a_max∕a_frag, and maximum size of dust grains a_max. The solid curves outline the disk regions with St < 0.01.