RESUMEN
Coal combustion, which is one of the most important energy sources of electricity generation, produces airborne pollutants: NOx, CO2, SO2, particulates and Hg°. A range of technologies is being developed to reduce the environmental impact of coal-fired power stations. No optimal technology that can be broadly applied exists as yet, but sorption of mercury is considered a promising approach. We report a novel adsorbent, which shows an extraordinary mechanical resistance and high adsorption capacity of mercury vapour. These adsorbent samples were synthesized in the gas sulphonitriding process using steel sheets. The chemisorption capacity of the sorbent materials, the process of the thermal desorption of mercury and the effect of the hydrogen activation treatment have been investigated in the work. It has been established that the capacity of mercury chemisorption increased more than twice after the heating treatment of the adsorbent in H2 atmosphere at 500 °C in comparison with the non-activated one. The mechanism of activation has been elucidated in the paper. For the purpose of comparison, activated carbon was also investigated.
RESUMEN
The aim of this study was to investigate post cryotherapy thyroid function status of normal rat thyroid tissue and to determine the topography of temperature of cryotreated tissues and of tissues adjacent to them. Nitrous oxide cryotherapy was performed in 40 male Wistar rats. They were divided into four groups of 10. In group I, the right thyroid lobe was subjected to cryotherapy and the left lobe was not frozen. In group II, both thyroid lobes were cryotreated. In group III, the right lobe was frozen and the left lobe was excised. In group IV, the thyroid was subjected to neither cryotherapy nor surgery. During cryotherapy, the temperature in various places of the thyroid and in the surrounding tissues was measured. Serum thyrotropin concentrations were determined before an experiment and 4 weeks after in all rats. The results of temperature measurements proved that it is possible to limit cryotherapy to certain areas of thyroid tissue and to spare the neighboring tissues, because they are not subjected to temperatures that are damaging. The effectiveness of cryotherapy was confirmed by functional effect. Cryotherapy changed function of thyroid tissue. There was a statistically significant difference between mean baseline and follow-up concentrations in rats of groups II and III. In both groups hypothyroidism occurred post cryotherapy.