Mechanism of propene poisoning on Fe-ZSM-5 for selective catalytic reduction of NO(x) with ammonia.

Application of Fe-zeolites for urea-SCR of NO(x) in diesel engine is limited by catalyst deactivation with hydrocarbons. In this work, we investigated the effect of propene on the activity of Fe-ZSM-5 for selective catalytic reduction of NO(x) with ammonia (NH(3)-SCR), and proposed a deactivation mechanism of Fe(3+) active site blockage by propene residue. The NO conversion decreased in the presence of propene at various temperatures, while the effect was not significant when NO was replaced by NO(2) in the feed, especially at low temperatures (<300 degrees C). The surface area and pore volume were decreased due to carbonaceous deposition. The site blockage was mainly on Fe(3+) sites on which NO was to be oxidized to NO(2). The activity for NO oxidation to NO(2) was significantly inhibited on a propene poisoned catalyst below 400 degrees C. The adsorption of NH(3) on the Bronsted acid sites to form NH(4)(+) was not hindered even on the propene poisoned catalyst, and the amount of absorbed NH(3) was still abundant and enough to react with NO(2) to generate N(2). The hydrocarbon oxygenates such as formate, acetate, and containing nitrogen organic compounds were observed on catalyst surface, however, no graphitic carbonaceous deposit was formed.

Metabonomic investigations into the global biochemical sequelae of exposure to the pancreatic toxin 1-cyano-2-hydroxy-3-butene in the rat.

The time-related metabolic effects of 1-cyano-2-hydroxy-3-butene (CHB, crambene), a naturally occurring nitrile and experimental model toxin causing exocrine pancreatitis, have been investigated in rats using high-resolution NMR spectroscopy of urine and serum in combination with pattern recognition analysis. Rats were administered CHB subcutaneously in two doses, 15 mg/kg dose (n = 10) and 150 mg/kg (n = 10), and conventional histopathology and clinical chemistry assessments were performed. Urine samples were collected at - 16 and 0, 8, 24, 48, 72, 96, 120, 144 and 168 h postdosing and serum samples were collected at 48 and 168 h postdosing; these were analyzed using a range of 1D and 2D NMR spectroscopic methods. The metabolic profile perturbations seen throughout the time-course of the study are described, and the application of the spectral correlation technique Statistical TOtal Correlation SpectroscopY (STOCSY) to detect both structural and novel toxicological connectivities between xenobiotic and endogenous metabolite signals is illustrated for the first time. As a result, it is suggested that the STOCSY approach may be of wider application in the identification of toxic versus nontoxic metabolites in drug metabolism studies.

Acute massive rhabdomyolysis due to prolonged inhalation of liquid gas.

A very rare case of non-fatal acute massive rhabdomyolysis caused by unintentional prolonged inhalation of liquid gas (consisting of butane and propane) in a previously healthy adult is presented. The immediate diagnosis and intensive symptomatic therapy prevented any other severe complications of rhabdomyolysis, and the patient made a complete recovery without any sequelae.

[Acute poisoning with industrial products]. / Intoxications aiguës par les produits industriels.

Poisonings with industrial products represent approximately 7% of the cases reported to the poison centres. Ingestion of petroleum distillates induces irritation of the gastrointestinal tract, central nervous system depression and aspiration pneumonitis which may be severe; treatment is mainly supportive. Ethylene and diethylene glycol poisonings produce central nervous system depression, anion gap metabolic acidosis, osmolar gap and acute tubular necrosis; in severe cases, hypocalcaemia, cerebral oedema and heart failure may be observed; treatment often associates supportive measures, haemodialysis and administration of competitive inhibitors of alcohol dehydrogenase (ethanol or 4-methylpyrazole). Glycol ethers induce central nervous system depression and metabolic acidosis; in addition, ethylene glycol monobutyl ether produces haemolysis; monomethyl and monoethyl ethers are responsible for bone marrow and lymphoid organ toxicity, they adversely affect spermatogenesis and are teratogens.

Toxicology of petroleum naphtha distillate vapors.

A unique opportunity was presented to observe the potentially toxic effects of an acute exposure to the vapors of petroleum naphtha distillate on a relatively large number of individuals. The immediate manifestation in all was dyspnea. The action on motor vehicle combustion suggested that some of this could have been due to oxygen deprivation; however, all individuals were dyspneic for several minutes after exposure. A few were cyanotic for several minutes after exposure. All were excited. Tremulousness and mild nausea followed the initial symptoms but were of brief duration. One individual manifested numerous premature ventricular contractions. Since his exposure was brief and since none of the others showed similar findings, it is unlikely that the exposure was causal. The central nervous system depression described in acute exposure cases of the intact (not distillate) petroleum naphtha fumes was not observed in any of this series. There were no delayed manifestations or complications.