Secondary pool boiling effects.

A pool boiling phenomenon referred to as secondary boiling effects is discussed. Based on the experimental trends, a mechanism is proposed that identifies the parameters that lead to this phenomenon. Secondary boiling effects refer to a distinct decrease in the wall superheat temperature near the critical heat flux due to a significant increase in the heat transfer coefficient. Recent pool boiling heat transfer experiments using femtosecond laser processed Inconel, stainless steel, and copper multiscale surfaces consistently displayed secondary boiling effects, which were found to be a result of both temperature drop along the microstructures and nucleation characteristic length scales. The temperature drop is a function of microstructure height and thermal conductivity. An increased microstructure height and a decreased thermal conductivity result in a significant temperature drop along the microstructures. This temperature drop becomes more pronounced at higher heat fluxes and along with the right nucleation characteristic length scales results in a change of the boiling dynamics. Nucleation spreads from the bottom of the microstructure valleys to the top of the microstructures, resulting in a decreased surface superheat with an increasing heat flux. This decrease in the wall superheat at higher heat fluxes is reflected by a "hook back" of the traditional boiling curve and is thus referred to as secondary boiling effects. In addition, a boiling hysteresis during increasing and decreasing heat flux develops due to the secondary boiling effects. This hysteresis further validates the existence of secondary boiling effects.

Intrathoracic cancer of the splenic flexure.

Blunt traumatic rupture of the diaphragm is a well known but uncommon event of thoracoabdominal traumatic injuries. It occurs in 1-5% of polytrauma patients and requires a high degree of suspicion for a rapid diagnosis. The frequency of delayed diagnosis is difficult to be estimated and up to 30% of blunt diaphragmatic ruptures present late. A case of herniated splenic colic flexure through a defect in the left hemidiaphragm and the subsequent development of colon cancer in this area are presented. We emphasize the importance of making a prompt diagnosis in order to avoid further morbidity and mortality in this rare clinical entity.

Laparoscopic cholecystectomy performed by surgical trainees.

OBJECTIVE: The aim of this study was to assess morbidity, mortality, and outcome in select patients after laparoscopic cholecystectomy performed by consultants or by Specialist Registrars (SpRs) and Senior House Officers (SHO), in the General Hospital of Ioannina 'G. Hatzikosta' in northwestern Greece. METHODS: Between January 1, 2001 and December 31, 2005, 1370 laparoscopic cholecystectomies were performed, 445 (33%) by SpRs and SHO and 925 (67%) by consultants. Patients included 982 (71.3%) women and 388 (28.7%) men. The mean age was 46.2 years (range, 17 to 79). All patients had routine blood tests (including liver function tests), electrocardiography, chest x-ray, and abdominal ultrasound scan performed preoperatively. All patients received a general anesthesia, and the standard Reddick and Olsen technique was performed. The Harmonic scalpel was used in all cases. RESULTS: Four conversions (0.3%) were required to an open procedure, (2 in the SpRs and SHO group and 2 in the group of consultants), because of impossible recognition of anatomy around Calot's triangle. The mean operative time was 57 minutes (range, 33 to 97) for SpRs and SHO, while for the consultants it was 49 minutes (range, 27 to 78, P=0.25). Mortality rate was 0% in both groups. There were 44 major complications (2.7%), 17 in the SHO and SpRs group (3.7%) and 27 in the consultant group (1.7%, P=0.11). The complications included bowel thermal injury (consultants [cons], 1; residents [res], none); bile duct injury (cons, 1; res, none); bile leak (cons, 3; res, 5); hemorrhage (cons, 2; res, 2); hematomas at the trocar sites (cons, 5; res, 4); inflammation of the port site at the umbilicus (cons, 4; res, 5); paralytic ileus (cons, 4; res, 3); and hemorrhage from the subxiphoid trocar (cons, 2; res, 3), which stopped spontaneously. The mean hospital stay was 1.3 days, while all the patients resumed their normal activities after 11.7 days (range, 7 to 19). CONCLUSION: Supervised laparoscopic cholecystectomy performed by trainees does not increase surgical morbidity and does not compromise surgical outcome.