Authors:J. Santos, L. Lima, Iêda Santos and A. Souza
The thermal degradation process of mineral base lubricating oils was
studied in this work by means of thermal, spectroscopic and rheologic analysis.
The lubricating oils were degraded at temperatures varying from 150 to 210C,
and for degradation times from 1 to 48 h. After the degradation, the lubricating
oils were characterized by X-ray fluorescence, IR and NMR spectroscopies,
rheological properties and thermal analyses (TG/DSC). The spectroscopic analyses
determined the oxidation reaction products. TG curves indicate that the thermal
stability of lubricating oils is below 161C. TG curves in air present
three mass loss stages, whereas in nitrogen there are only two mass loss steps.
DSC analyses in air indicate two highly exothermic peaks related to hydrocarbon
oxidation and combustion processes, while in nitrogen only two endothermic
peaks were observed. The decrease in the degradation temperature led to a
decrease of the lubricant viscosity.
The development of an automated water target for the production of18F is described. The system was fully fested and shown to be reliable and secure. The chemical separation of18F was carried out using an anionexchange resin and K2CO3 as eluent. The18F production yields were, on average, (4.81±0.42) MBq/Ah and the specific activity was higher than 6.623×105 MBq/mmol. Heat transfer measurements and calculations were made.
Authors:N. Santos, J. Santos, F. Sinfrônio, T. Bicudo, I. Santos, N. Antoniosi Filho, V. Fernandes and A. Souza
The babassu (Orbignya Phalerata Mart.) biodiesel has lauric esters as main constituents, resulting in high oxidative stability and low cloud and freezing
points. In order to reduce these side effects, the saturated ethyl esters content was reduced by means of winterization process.
The TMDSC and PDSC techniques were used to verify the thermal and oxidative stabilities of the ethyl babassu biodiesel. During
the heating stage, the winterized solid phase of ethyl esters presented an endothermic transition associated to the solidification
process. This behavior was not observed for the liquid winterized FAEE, confirming the efficiency of the winterization process.
Authors:J. Santos, C. Munita, M. Valério, C. Vergne and P. Oliveira
Instrumental neutron activation analysis (INAA), have been used for the definition of compositional groups of potteries from
Justino site, Brazil, according to the chemical similarities of ceramic paste. The outliers were identified by means of robust
Mahalanobis distance. The temper effect in the ceramic paste was studied by means of modified Mahalanobis filter. The results
were interpreted by means of cluster, principal components, and discriminant analyses. This work provides contributions for
the reconstruction of the prehistory of baixo São Francisco region, and for the reconstitution of the Brazilian Northeast
ceramist population of general frame.
Authors:A. Azeredo, L. Julião, M. Santos, D. Melo and J. Lipsztein
Internal contamination with radioactive materials of mining workers is a common problem in Brazil. This is caused by the presence of uranium, thorium, and their natural decay series associated with the mined ore. The clear examples are the workers at the niobium mine located in the state of Goiás. The niobium is associated with considerable quantities of uranium and thorium, but the mine is not legally subject to radiation protection requirements.Twenty mine workers were evaluated using in vitro bioassay techniques (urine and feces). The fecal samples were analyzed by alpha spectrometry using the method developed in the Bioassay Laboratory of the Instituto de Radioproteção e Dosimetria/CNEN which evaluates thorium and uranium isotopes simultaneously. Minor modifications were introduced to measure a higher level of activity, around 1 Bq of uranium per sample. The urine samples were analyzed by alpha spectrometry for thorium and by fluorimetry for uranium. The results obtained show that a control of the occupationally-exposed workers is necessary.
Authors:J. Souza, A. Santos, L. Polese, Marisa Crespi and C. Ribeiro
Poly(3-hydroxybutyrate), PHB has been structurally
modified through reaction with maleic anhydride, MA. Transesterification reaction
was carried out fixing the PHB and MA and besides time and temperature the
concentration of the triethylamine (used as catalyst) was changed. Glass transition,
melting and crystallization temperature obtained from DSC curves and thermal
degradation temperatures obtained from TG traces were used to evaluate the
influence of the reaction conditions on the modification of PHB according
to factorial design. On the base of the results the optimum conditions are
to perform the PHB modification reaction with MA reaction at 110C for
1 h with 5% v/v triethylamine.
Authors:L. Cides, A. Araújo, M. Santos-Filho and J. Matos
the present work, the thermal decomposition of glimepiride (sulfonylurea hypoglycemic
agent) was studied using differential scanning calorimetry (DSC) and thermogravimetry/derivative
thermogravimetry (TG/DTG). Isothermal and non-isothermal methods were employed
to determine kinetic data of decomposition process. The physical chemical
properties and compatibilities of several commonly used pharmaceutical excipients
(glycolate starch, microcrystalline cellulose, stearate, lactose and Plasdone)
with glimepiride were evaluated using thermoanalytical methods. The 1:1 physical
mixtures of these excipients with glimepiride showed physical interaction
of the drug with Mg stearate, lactose and Plasdone. On the other hand,
IR results did not evidence any chemical modifications. From isothermal experiments,
activation energy (Ea)
can be obtained from slope of lntvs. 1/T at a constant
conversion level. The average value of this energy was 123 kJ mol–1.
For non-isothermal method Ea
can be obtained from plot of logarithms of heating rates, as a function of
inverse of temperature, resulting a value of 157 and 150 kJ mol–1,
respectively, in air and N2 atmosphere, from the first
stage of thermal decomposition.
Authors:A. Ferreira, M. Saiki, J. Santos, A. Ribeiro and P. Saldiva
In this study, Canoparmelia texana lichenized fungi species was used as a passive biomonitor of the atmospheric pollution from the industrial city of São Mateus
do Sul, PR, Brazil. Lichen samples collected from tree barks were cleaned, freeze-dried and analyzed by neutron activation
analysis. Comparisons were made between the element concentrations obtained in lichens from this city and that from a clean
area of Atlantic Forest in Intervales Park, SP. The high concentrations of elements As, Ca, Co, Cr, Fe, Hf, Sb, and Th found
in lichens could be attributed to the emissions from a ceramic and an oil shale plants.