Multi-stage decomposition of 5-aminotetrazole derivatives: kinetics and reaction channels for the rate-limiting steps.

The thermal behavior, decomposition kinetics and mechanisms of 1-amino-1-(tetrazol-5-yldiazenyl) guanidine (tetrazene) and 2-(tetrazol-5-yldiazenyl) guanidine (MTX-1) have been investigated using DSC, TG techniques, and quantum chemical calculations. It has been found that MTX-1 is much more stable than tetrazene and MTX-1, and both of them decompose in three steps with different kinetic parameters. Tetrazene is melted-dehydrated at 128.4 °C with a heat absorption of 50 J g(-1) and then it starts to decompose at around 118.6 °C with a peak temperature of 126.3 °C covered by a heat release of 1037 J g(-1) at a heating rate of 1.0 °C min(-1), while MTX-1 starts at 167.7 °C with a main peak of 191.1 °C covered by a heat change of 1829 J g(-1) under the same conditions. The activation energy is almost the same for their first decomposition steps (225 kJ mol(-1)), which are controlled by a three dimensional nucleation and growth model (A3). The mechanisms of the rate-limiting steps are supported by quantum chemical calculations. They could undergo a similar rate-limiting chemical process producing 1H-tetrazole and N2 for both cases, while the former also produces aminocyanamide and the latter produces cyanamide.

Spontaneous bacterial peritonitis in the Czech Republic: prevalence and aetiology.

The aim of the study was to determine the prevalence and detailed data concerning the incidence of spontaneous bacterial peritonitis in the Czech Republic. Ninety-nine patients with liver cirrhosis and ascites were examined. Spontaneous bacterial peritonitis was diagnosed in 35 patients (35.4%). It was revealed more often in patients with alcoholic aetiology of cirrhosis whose anamnesis involved sub-febrile or febrile states and the deterioration of ascites. Elevated serum leucocyte counts and increased levels of C-reactive protein can contribute to the diagnosis. A low level of total protein and albumin in ascites predisposes to the increase of this infection. The reduction of the platelet count in a set of patients with spontaneous bacterial peritonitis indicates the influence of portal hypertension in the aetiology of the disease.

Sensitivity to friction for primary explosives.

The sensitivity to friction for a selection of primary explosives has been studied using a small BAM friction apparatus. The probit analysis was used for the construction of a sensitivity curve for each primary explosive tested. Two groups of primary explosives were chosen for measurement (a) the most commonly used industrially produced primary explosives (e.g. lead azide, tetrazene, dinol, lead styphnate) and (b) the most produced improvised primary explosives (e.g. triacetone triperoxide, hexamethylenetriperoxide diamine, mercury fulminate, acetylides of heavy metals). A knowledge of friction sensitivity is very important for determining manipulation safety for primary explosives. All the primary explosives tested were carefully characterised (synthesis procedure, shape and size of crystals). The sensitivity curves obtained represent a unique set of data, which cannot be found anywhere else in the available literature.