Theoretical and experimental approach of fuel gas and carbon black production from coal tar pitch by thermal plasma process.

The processing of coal tar pitch (CTP) to produce clean fuel gas and carbon black (CB) is studied in a plasma reactor equipped with a direct-current plasma torch. The composition of the gas produced and energy costs were estimated theoretically for the CTP pyrolysis and gasification processes by two oxidants, namely oxygen and water vapor. We have found that the main gaseous compounds obtained in the pyrolysis and gasification processes are hydrogen (H2), carbon monoxide (CO), and very often carbon dioxide (CO2). For the pyrolysis case, the mean value of the synthesis gas concentration reaches a major value of 98 vol.% (H2 - 81 vol.%, CO - 17. vol.%). However, only 23% of the initial CTP is transformed into gas phase at 1100 K and its content increases up to 37.4% at a temperature of 3000 K. For oxygen gasification, the syngas quantity is little less compared to the pyrolysis case and attains 96.6 vol.% (H2 - 26.5 vol.%, CO - 70.1 vol.%) for T > 1100 K. An intermediate syngas content for the water steam gasification is 97.8 vol.% (with H2 - 55.8 vol.% and CO - 42.0 vol.%). The CB produced was composed of well-defined spherical particles of 30-nm size. Furthermore, it is composed of carbon (98.2%), and followed by oxygen (1.8%) with a surface area of 97 m2 g-1. The thermal plasma system shows high efficiency in conversion of CTP into high-value-added products.

Evaluation of thermal plasma process for treatment disposal of solid radioactive waste.

The management of radioactive waste is a worldwide activity based on the guidelines of the International Atomic Energy Agency (IAEA), and all stages of management require scientifically proven methods for possible deployment. The management of radioactive waste is a huge challenge due to the high risk in the collection, gathering, transport, handling, and storage. In this study, a thermal plasma treatment process was evaluated for its efficiency to process solid radioactive waste. Experiments were carried out with the application of stable isotopes of Lead, Iodine, Cobalt, and Cesium. After the thermal plasma treatments, the slag and the residual gas were analyzed to verify the influence of process time and discharge power on the efficiency of the process. The treatment for 25 min and 10 kW was sufficient to reduce the mass by 50% of the slag. When the applied power was increased to 15 kW, an expressive reduction in the treatment time (10 min) was able to promote the same mass reduction. The results indicated that the treatment of radioactive waste by thermal plasma is a promising method to manage and reduce the mass and volume for the final disposal.

Virus diarrhea of the infant mice. Ultrastructure of the intestinal epithelium (author's transl). / Diarréia a vírus dos camundongos lactentes. aspectos ultraestruturais do epitélio intestinal.

The authors studying ultrastructure of epithelium of infant mice infected with the agent of diarrhea, detected virus particles agglutinated in vesicles measuring 59 +/- 2.00 (0.988) nm. This particles had a core more dense with 30 +/- 2.00 (0.705) nm and was found in all animals studied, sick, normal or with inapparent disease.