Separation and purifying andrographolide by supercritical carbon dioxide gradient crystallization were made.

Testing results indicated that DSC fusion curve of samples prepared by means of gradient isothermal crystallization revealed multiple fusion peaks, good repetition of testing results, high differentiation between different samples facilitating a reliable fast appraisal of unknown quality of g.

Study on the coated cemented carbide with gradient structure by a special sintering technology;

Coated cemented carbide with gradient structure;

Effects of carburizing process on gradient structure and hardness of WC-Co gradient cemented carbides;