Laparoscopic surgery of large uterine fibromas. Operative technique and results

OBJECTIVE. To describe the technique of laparoscopic myomectomy for large myomas (5 cm and more) and to evaluate the results. RESULTS. Only myomas which are complicated (and/or resistant to properly conducted medical treatment) require surgical treatment. Between October 1, 1990 and October 31, 1994, we carried out 72 laparoscopic myomectomies for intramural myomas measuring 5 cm or more, in 71 patients. The operations lasted 130 +/- 60 min (range: 40-330 min). We converted to laparotomy for two cases (2.7%). We observed no serious per or postoperative complications. We never needed a repeat operation, whether by laparotomy or by laparoscopy. CONCLUSION. Despite these encouraging results, it must be remembered that the operation is lengthy and difficult and is reversed for laparoscopic surgeons perfectly familiar with endoscopic knot tying. Although it is a difficult technique, laparoscopic myomectomy is possible even for large myomas and those that are completely intramural. These results need to be assessed over the long term especially with respect to the risk of adhesions and the quality of the laparoscopic suture.     

SIMULATED DISTILLATION BY TRERMO GRAVIMETRIC MEASUREMENTS APPLIED TO THERMAL CRACKING AND THERMAL HYDROCRACKING

ABSTRACT

A suitable correlation can be made to represent the simulated distillation of heavy oils starting from thennoaravimetric measurements. This method is applicable to hydrocarbons having an initial boiling point equal or greater than 200°C.

The simulated thermogravimetric distillation fit was obtained from experiments with the standard compounds obtained from ASTM D-2887-83 (Boiling range distribution of petroleum fractions by gas chromatography). This method is simple, fast and without problems when applied to heavy feedstocks

The data were used in the determination of average boiling temperatures of products from thermal cracking and thermal hydrocracking. It was also possible to quantify coke yields

Average relative molecular masses of products from the above processes correlated well with the average boiling point temperatures. It indicates that, with respect to the hydrocarbon types, thermal cracking is not selective in comparison with thermal hydrocracking

The equation applied to find the average boiling temperature is following: T = (1/al) (Ttg-a2). T is the boiling temperature, al and a2 are the correction factors, Ttg is the thermogravimetric temperature.     

Hydrogen production over Rh/Ce-MCM-41 catalysts via ethanol steam reforming

1 wt%Rh/Ce-MCM-41 catalysts were synthesized using Ce-MCM-41 as support where Si/Ce molar ratio varied from 10 to 30 and 50. During hydrogen reduction process, metallic Rh particles were formed on the Ce-MCM-41 at around 130 °C with an average particle size 6.8 nm. These catalysts were tested in the ethanol steam reforming (ESR) under atmospheric pressure between 225 and 425 °C. Compared to Rh/MCM-41 catalyst, cerium introduction would significantly enhance both the catalytic activity and hydrogen yield by approximately 2–3 times. However, the amount and the method of Ce incorporation in the framework of MCM-41 could greatly impact the catalytic performance of the Rh/Ce-MCM-41 catalysts. The ethanol conversion at 425 °C over the Rh/Ce-MCM-41 catalysts increased from 90.0% to 95.1% and 99.9%, as the Si/Ce molar ratio increases from 10 to 30 and 50. However, product selectivity is almost independent of the cerium content. The direct hydrothermal method of introducing Ce into the framework of MCM-41 is much superior to the impregnation route in the ESR reaction. After 6 h of reaction, the catalysts remain the mesostructure and the chemical state of cerium ions unchanged. Trace coke with graphite-like structure deposited on the surface does not modify the catalytic performance.