Introduced as replacements for ozone depleting substances, HFCs do not damage the ozone layer but are potent global warming agents and considered 'super' greenhouse gases.

The quality analysis for gas nitrocarburized inner gear ring of heavy truck imported from Austria was taken by means of macro/micro-examination, hardness measuring and running test.

The paper introduces the concept of significant density and explores the critical temperature of Bose-Einstein condense(BEC) in the ball harmony potential well in the ideal Bose gas.