Clinical characteristics of remote Zeus robot-assisted laparoscopic cholecystectomy:A report of 40 cases

AIM： To summarize the performing essentials and analyze the characteristics of remote Zeus robot-assisted laparoscopic cholecystectomy. METHODS： Robot-assisted laparoscopic cholecystectomy was performed in 40 patients between May 2004 and July 2005. The operating procedures and a variety of clinical parameters were recorded and analyzed. RESULTS： Forty laparoscopic cholecystectomy procedures were successfully completed with Zeus robotic system. And there were no post-operative complications. Total operating time, system setup time and performing time were 100.3±18.5 min, 27.7±8.8 min and 65.6±18.3 min, respectively. The blood loss and postoperative hospital stay were 30.6±10.2 mL and 2.8±0.8 d, respectively. Camera clearing times and time used for operative field adjustment were 1.1±1.0 min and 2.0±0.8 rain, respectively. The operative error was 7.5%. CONCLUSION： Robot-assisted laparoscopic cholecystectomy following the principles of laparoscopic operation has specific performing essentials. It preserves the benefits of minimally invasive surgery and offers enhanced ability of controlling operation field, precise and stable operative manipulations.

Real-time observation of bainite formation at heterogeneous phases in a high-strength weathering steel

Due to the excellent comprehensive mechanical properties and toughness of bainite steels,bainite is regarded as a most desirable microstructure for the new generation of high-strength weathering steels.The formation of bainite was observed in real time in a high-strength weathering steel,and the results showed that bainite laths show impingement during phase transformation.The preferred regions of nucleation sites were identified,and the growth rate of bainite was measured.The growth mechanism of bainite was demonstrated to exhibit growth rate contributions from both the diffusion mechanism and the shear mechanism.Subsequently,the heterogeneous phases that form preferred sites for bainite nucleation were quantitatively identified by scanning electron microscopy(SEM),energy-dispersive X-ray spectrometry(EDS),and calculation of phase diagram(CALPHAD).The austenite grain sizes in crease with increasing austenite temperature,which leads to longer bainite laths.The influence of a small lattice disregistry between the heterogeneous phases and bainite on the bainite nucleation was studied.The disregistries between the favorable heterogeneous phases of VN,VC,TiN,or TiC and the ot-Fe in bainite are 2.9,3.1,3.9,and 4.6%,respectively.Therefore,VN,VC,TiN,and TiC can act as highly effective nuclei for bainite during the bainite transformation.

Influence of N/C ratio on microstructure and properties of new highstrength weathering steels

Influence of the N/C ratio on the microstructure and properties of new-generation high-strength weathering steels was investigated using calculation of phase diagram(CALPHAD)and experiments.The microstructures of weathering steels containing different N/C ratios were predicted by a CALPHAD approach,and only three phases were predicted in these steels within the rolling temperature range of 850-1050℃.The precipitation fraction of VN/V(C,N)in creases with increasing N/C ratio.Microstructures of the four tested steels were all experimentally determined to contain bainite,ferrite,and VN precipitates after air cooling to room temperature.The bainite fraction increases with in creasing N/C ratio,and it is 85%in the steel containing 0.038% N and 0.032% C,The results of the tensile tests and impact tests demonstrated that the yield strength and tensile strength of the steel containing 0.038%N and 0.032%C are greater than 550 and 650 MPa,respectively,and the elongation is greater than 24%,which satisfies the design objectives for mechanical properties.The impact toughness values of the four steels at 0,-20,and-40℃ are all greater than 24 J.With increasing N/C ratio,the bainite fraction and the precipitation fraction of VN/V(C,N)increase,resulting in increasing yield strength and tensile strength.