Abstract Although most of the studies presented in the literature are focused on MgAl2O4 formation and its role on alumina-based refractories performance, ZnO has been reported as a promising spinel inducer. Aiming to investigate the influence of ZnAl2O4 (ZA) and MgAl2O4 (MA) generation on the properties of alumina-based castables, three vibratable compositions containing calcium aluminate cement or hydratable alumina as binders and 1 wt% of silica fume, were evaluated in this work. Flexural strength, apparent porosity, hot elastic modulus, corrosion cup-tests, thermodynamic simulations, were carried out to analyze the performance of such ceramics. The results indicated that ZnAl2O4 was mainly formed above 800 °C, favoring an earlier sintering of the samples. Besides that, the softening of the castables was observed above 1200 °C, which resulted in the elastic modulus decay of the samples during their first heating cycle due to the formation of SiO2-rich liquid phase in the resulting microstructure. Cement-free samples obtained after calcination (600 °C for 5h) presented enhanced corrosion resistance when placed in contact with molten slag at 1500°C. Although, silica fume addition to the castables negatively affected their corrosion performance, it helped to counterbalance the expansion associated with the spinel and calcium aluminates formation.

Compararam-se os efeitos analgésico, sedativo e neuroendócrino decorrentes da administração epidural e intramuscular da metadona em gatas submetidas à ovariossalpingoisterectomia (OSH). Todos os animais foram tranquilizados com acepromazina, 0,1mg kg-1 IM, seguindo-se a indução e manutenção anestésica com tiopental sódico, 12mg kg-1 IV, e halotano, respectivamente. Após a estabilização anestésica, os animais foram distribuídos em três grupos, com oito animais cada, tratados com metadona pela via epidural (EP) ou intramuscular (IM) 0,2mg kg-1, respectivamente, ou com solução salina (S) 0,2mL kg-1. Foram avaliados: graus de analgesia e de sedação, necessidade de analgesia de resgate, efeitos adversos e concentração sérica de cortisol. Os graus de analgesia e de sedação e o cortisol não diferiram entre os tratamentos. Analgesia de resgate foi administrada quatro, nove e 11 vezes nos tratamentos EP, IM e S, respectivamente. Nos tratamentos IM e S, a suplementação analgésica foi necessária a partir da primeira hora pós-cirúrgica, enquanto no tratamento EP, somente a partir da terceira hora após a OSH. Conclui-se que a administração de metadona pela via epidural resulta em menor quantidade do analgésico pós-operatório, e que a analgesia é mais prolongada quando comparada à obtida pela via intramuscular, em gatas submetidas à OSH.

The aim of this study was to investigate the analgesic, sedative and neuroendocrine effects of epidural (EP) and intramuscular (IM) methadone in cats submitted to ovariohysterectomy. The pre-anesthetic medication was acepromazine (0.1mg kg-1, IM) followed by induction of anesthesia with intravenous thiopental, 12mg kg-1, and anesthesia maintenance with halothane. After anesthesia stabilization the cats were randomly assigned to three groups of eight animals each and received EP or IM methadone, 0.2mg kg-1 diluted with saline to 0.2mL kg-1, EP and IM, respectively, or a saline placebo (S), 0.2mL kg-1. Pain measurements, degree of sedation, rescue analgesia requirements, adverse effects and serum cortisol concentration were recorded. Cortisol, pain and sedation scores did not differ among the groups. Rescue analgesia was administered 4, 9 and 11 times in the EP, IM and S treatment, respectively. In the IM and S rescue analgesia treatments were required early (first hour postoperative), whereas in the EP treatment, additional analgesics were required after the third hour postoperative. In conclusion, methadone epidural reduced the postoperative analgesic requirements and produced longer analgesia when compared to intramuscular administration in cats undergoing ovariohysterectomy.