Reaction kinetics of acetone peroxide formation and structure investigations using Raman spectroscopy and X-ray diffraction.

Triacetone triperoxide (TATP) has been prepared in order to study the effect of pH and temperature on the reaction kinetics. Raman spectra of liquid mixtures of acetone and hydrogen peroxide were recorded versus time throughout the experiments. The spectral data of the liquid phases indicate that at 25 degrees C the reaction between acetone and hydrogen peroxide proceeds to form intermediates within one day. Based on the assumption that a likely reaction path involves a sequence of reaction steps between acetone and hydrogen peroxide, calculations of Raman spectra were performed using a density functional theory (DFT)/Hartree-Fock approach. It was not possible from this to assess with certainty which intermediate products formed most extensively in an acetone/hydrogen peroxide mixture. However, it was concluded that the most likely reaction mixture is a mixture of the different intermediate products and that the rate determining step is the ring closure. The reaction rate of TATP formation was found to increase with temperature and with sulfuric acid additions to the acetone/hydrogen peroxide mixture. By correlation of the induction time of TATP crystallization against pH it was shown that the reaction rate is first order with respect to the H+ concentration. Raman spectra of the precipitates from mixtures were in agreement with previous studies done for TATP, except in one case in which a crystal crystallized at 343 K had a distinctly different Raman spectrum. Comparison with calculated spectra revealed that the crystal produced could be diacetone diperoxide (DADP) or tetraacetone tetraperoxide (TrATrP). Single crystal X-ray diffraction analyses revealed that the crystal crystallized at 343 K was DADP.

[Congenital tracheobiliary fistula]. / Kongenit trakeobiliaer fistel.

A case of congenital bronchobiliary fistula in a three-year old girl is reported. The patient was born after 40 weeks of gestation and referred due to a long history of respiratory tract problems. Bronchoscopy disclosed a third opening at the level of the carina. The opening was cannulated with an X-ray positive catheter, and a fistula crossing the diaphragm and communicating with the left hepatic duct was found. Cholescintigraphic examination (HIDA-scanning) confirmed the presence of the fistula, but found no evidence of abnormalities in the rest of the biliary system. The thoracic portion of the fistula was excised through a right side thoracotomy. The postoperative course was uncomplicated. HIDA-scanning one month after the operation showed normal uptake, and the girl's symptoms had disappeared.

[Laparoscopic ultrasonography. A review and authors' own experiences]. / Laparoskopisk ultralydskanning. Oversigt og egne erfaringer.

Laparoscopic ultrasound scanning has long been available, but interest in and reports of the technique have until the last few years been sporadic. The rapid development and growing interest in laparoscopic surgery as well as the advent of commercially available systems designed for laparoscopic ultrasound have resulted in renewed interest in the technique. The available published reports lack prospective, controlled clinical studies with respect to where and when laparoscopic ultrasound would be indicated. A favourable picture is given as concerns the use of laparoscopic ultrasound in the diagnosis and evaluation of primary liver and pancreas tumours as well as liver metastases. Laparoscopic ultrasound is also mentioned as a reliable alternative to cholangiography in laparoscopic cholecystectomy. Our own preliminary experiences with two laparoscopic ultrasound systems and a simple system using an ultrasound finger-probe are described. A laparoscopic ultrasound scanning system consisting of a stiff instrument with a convex (linear) transducer mounted on a flexible support and with the possibility of ultrasound-guided biopsy and colour-Doppler seems optimal. Prospective studies are being carried out to identify areas of utilization and limitations of laparoscopic ultrasound.