Crystal morphologies on a cordierite glass surface

With suitable thermal treatments, a nearly stoichiometric cordierite glass (2 MgO.2 Al2O3. 5 SiO2) shows a variety of crystal morphologies on the external surfaces: lozenges, regular and elongated hexagons, spherical and square shaped particles. We initially identified these morphologies through optical and scanning electron microscopy techniques. Their structural features were distinguished by x-ray diffraction patterns, infrared and Roman microprobe spectra. We concluded that there are close structural similarities for: lozenges and glass matrix; regular and elongated hexagons; spherical and square particles. The ordering degree increases in the following sequence: glass matrix, lozenges, hexagons, squares and spheres. The lozenge crystals are known as X-phase. The hexagons belong to the μ-cordierite (high quartz solid solution) metastable phase and the squares and spheres to the α-cordierite stable phase.

Análise retrospectiva da toxicidade de gotas otológicas, medicamentos tópicos nasais e orofaríngeos registrada na Grande São Paulo.

BACKGROUND: Retrospective analysis of human toxicity files involving topical medicines for treatment of upper airways diseases (eardrops, topical nasal medicines, lozenges, drops and sprays for oropharyngeal affections). METHODS: Thirty-four brands of eardrops, 48 of topical nasal medicines and 22 of tablets, lozenges and sprays for oropharyngeal affections were selected, from a total of 104 products available in Brazil. We analyzed the registries in the electronic database from the Poison Control Centre of São Paulo (CCI-Jabaquara), Brazil, for the period from January 1996 through December 2000. The cases related to selected pharmaceuticals were collected. RESULTS: 10,823 cases of human toxicity caused by medicines were voluntarily reported to CCI-Jabaquara. Topical medicines for treatment of upper airways diseases accounted for 291 cases (2.68%), from which 240 (82.5%) represented poisoning; 12 (4.1%) involved ear drops, 268 (92%), topical nasal medicines and 11 (3.9%), topical medicines for oropharyngeal affections. Among topical nasal medicines, vasoconstrictors predominated (233 cases), and among medicines for oropharyngeal affections, it was tetracaine (four cases). Considering age distribution, toxicity predominated significantly in children aged from 1 to 4 years (p=0.0003). The main causes of toxicity were: accidental intake of medicines (43%) and error in drug administration (14.8%). Hypereflexia and vomiting were the most frequent symptoms related to toxicity. CONCLUSIONS: There was significant incidence of systemic toxicity due to eardrops, topical nasal and oropharyngeal medicines in children 1 to 4 years-old, whose main cause was accidental intake of these medicines.

Desenvolvimento de pastilha potencialmente probiótica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)