The conditions, main reactions and reaction mechanism of coal gas explosion are analyzed. Moreover, some preventive and emergency measures for coal gas explosion are given, and approaches for making rational use of coal gas are introduced.

Rice bran is the surface layer of brown rice, its chemical composition includes carbohydrate, fat, protein and vitamin etc. The rice bran resource is abundant in our country, but its nutritive value and benefits are not developed fully. In this paper, the isolated substances in rice bran refining process and their application are introduced.

The coloration mechanism of gemstones is discussed by chemical composition and absorption spectrum. The colorations of ruby, sapphire, and emerald result from the d-d electron transition and charge transfer transition of transition metal ions such as chromium, iron, titanium etc. The colorations of ruby and sapphire are not simply dependent on the content of chromium or/and iron, but more dependent on the ratio of Fe²⁺/Ti⁴⁺and Fe³⁺/Fe²⁺. The coloration of emerald results from the effect of transition metal ions such as iron, chromium and vanadium etc. The coloration of gemstones may also relates to other transition metal ions and color centers, which may contribute more beautiful color.