In order to ensure work properly of residual current circuit breakers, the necessity to select the operating characteristic of the residual current circuit-breakers reasonably was described, that is to select the different operating current and different breaking time according to indirect contact protection and direct contact protection, or the fire protection due to electric fault.

The purity of the marrow mesenchymal stem cells (MSCs) which were examined by flow cytometry is 97%, then divided into five groups, group A: DMEM medium inducing group (control group); group B: 5-azacytidine inducing group; group C: myocardial cell lysate inducing group; group D: 5-azacytidine and myocardial cell lysate inducing group; group E: MSCs with cardiomyocytes indirect contact group.

This paper summarizes HVDC transmission systems which are operating or underbuilding all over the world and gives a brief description of newest modern techniques applied in HVDC systems, such as direct light-triggered thyristors, insulated gate bipolar transistors and earthing pole failure detectors etc.