1. Factors influencing the casting charge number of tundish are analyzed. Measures to increase the casting charge number are presented and the measures are proved to be very effective in practice.

2. The more charge number the dust grain carries the more obvious the magnetic field effects on it.

3. By introducing "the effective nucleus charge number for the potential", the physical features of argon atom field have been discussed.

4. At both sides as the ion charge number is increased, the conductivity in LHW driven plasma decreases, but the ratio of this conductivity and the Spitzer-Harm conductivity increases.

5. The orbit-limited motion method is adopted to study the dust charge number and the radius of dust particles in polar summer mesopause.