Optical signals occurred during the pre discharge and the breakdown over the spacer in sulfur hexafluoride gas are investigated by using a photomultiplier tube and a high speed framing camera under the fast oscillating impulse voltages (FOI) or lightning impulse voltages (LI).

The reasons and harm of CF 4 generated from anode polarization of fluorine cells in the SF 6 production are introduced.

The online low- humidity monitor of the moisture of SF 6 is very important for safe operation of SF 6 electrical apparatus.

The structural characteristics of the assorted and independent SF 6 voltage transformers are in troduced.

The accident process of 500 kV SF_6 current transformer in a substation is introduced,the reason is distinguished that there is bubble on support insulator which has caused partial discharge and led to surface flashover of support insulator,and the corresponding preventive measures are put forward.

To get the exactly breakdown voltage of SF_6 in actual electrode,the breakdown experiment is compulsory before the structure design of high voltage apparatus.

Based on the CPLD, this paper designed a scheme of serial data communication of the ultrasonic alarming system for gas SF_6.

Microleakage between tooth canal dentin and four dual-cure composite cements for bonding fiber post after thermocycling;

In vitro study of marginal microleakage of four composite resins;

Infection on Marginal Microleakage of ONE-UP BOND F and 3M ESPE Single Bond 2 to Restorations;

Quantitative analysis of remaining oil in polymer flooding microscopic seepage images;