The original purpose of this investigation started in 1996 was to study the radiological impact on the local population of
the village of Chichiviriche de La Costa. But, soon after the major earthquake (Ms=6.8) in the state of Sucre on July 9, 1997,
the objective was changed to study the fluctuation of radon (222Rn) to see if it could be correlated to seismic activity and/or if the amonlous change just before the earthquake can be considered
a precusor for it. Measurements of222Rn by simply de-gassing about 250 ml of natural thermal water employing a Pylon AB-5 radiation monitor and counting the radiation
after it reached equilibrium were performed. The values for four sampling periods in the first half of 1996 were about 17
Bq/l of222Rn, a month before the earthquake they were less than 15 Bq/l and increased about 70% to 25 Bq/l two days before the seismic
event. In about two weeks, they returned to about 18 Bq/l. But, surprisingly, they have gradually increased to about 35 Bq/l,
before leveling off at about 27 Bq/l.
Authors:D. Palacios, D. Castro, M. Perez, F. Urbani, L. Sajo-Bohus, and J. LaBrecque
The concentrations of40K,226Ra,232Th and137Cs were determined in the upper layers of soils in the central coastal region of Venezuela. The activities of137Cs are higher in the areas where the forest is well developed, oriented towards the wind and at higher elevations. The origin
of the137Cs deposition is from water input from the clouds directly in the cloudforest and rainfall from the northeast trade winds.
Even though the values of137Cs are much higher in these areas, there is little or no significant increase in the health risk. The natural radioactivity
is correlated with the geology in the region except in the area of Urama. The values for the natural radiation background
are as follows: for potassium between 1–3%, for radium between 1–3 ppm and for thorium the range was 6–39 ppm. The corresponding
amounts of absorbed dose rates in air, the exposure rates and the annual effective dose equivalents are in the following ranges
respectively: 11–39 pGy/s, 4–16 uR/h and 0.25–0.86 mSv/y. The annual effective dose equivalents include the contribution of
the global average (2.57 mSv/y) of the rest of the natural sources of radiation. Finally, the largest natural radioactivity
background, was found near Chichiriviche as a result of the massive granite deposits in this area, but again there is no significant
Authors:M. I. Yoshida, M. A. Oliveira, E. C. L. Gomes, W. N. Mussel, W. V. Castro, and C. D. V. Soares
Thermogravimetry (TG) and differential scanning calorimetry (DSC) are useful techniques that have been successfully applied in the pharmaceutical industry to reveal important information regarding the physicochemical properties of drug and excipient molecules such as polymorphism, stability, purity, and formulation compatibility among others. In this study, lovastatin was studied by TG, DSC, and other techniques such as Fourier transform infrared spectroscopy, optical microscopy, X-ray diffraction, chromatography, and mass spectrometry. Lovastatin showed melting point at 445 K and thermal stability up to 535 K. It presented morphological polymorphism, which in the drug has the same unit cell, but with different crystal habits. Preservative excipient butylhydroxyanisole (BHA) causes amorphization of lovastatin crystallites and, therefore is incompatible with lovastatin. Degradation by hydrolysis was observed under neutral, acid, and basic conditions. The active degradation product, lovastatin hydroxyacid, was obtained after neutral and basic hydrolysis.
Authors:Késia K. V. Castro, Ana A. D. Paulino, Edjane F. B. Silva, Thiago Chellappa, Maria B. D. L. Lago, Valter J. Fernandes Jr., and Antonio S. Araujo
Thermogravimetry (TG) was used in this study to evaluate thermal and catalytic pyrolysis of Atmospheric Petroleum Residue (ATR) which can be found in the state of Rio Grande do Norte/Brazil, after a process of atmospheric distillation of petroleum. The utilized sample in the process of catalytic pyrolysis was Al-MCM-41, a mesoporous material. The procedures for obtaining the thermogravimetric curves were performed in a thermobalance with heating rates of 5, 10, and 20 °C min−1. From TG, the activation energy was determined using the Flynn–Wall kinetic method, which decreased from 161 kJ mol−1, for the pure ATR, to 71 kJ mol−1, in the presence of the Al-MCM-41, showing the efficiency of the catalyst in the pyrolysis of Atmospheric Petroleum Residue.