The spatial distribution of Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) was analysed in ornamental crops (roses and spray-type carnations) and horticultural crops (pepper and strawberries), inside greenhouses, using sticky traps. In ornamental crops, at low population densities, during the winter, there was not a constant location of the isolated foci of infestation, from one week to the next, or a specific pattern of variation in that location. In spray-type carnations, pepper and strawberries, at higher population densities, in spring and summer, the basic units of distribution were the individuals, and they were aggregated. For roses, at those population levels, a random distribution was observed, with a tendency for aggregation. The number of traps needed to estimate population densities, in each crop, was evaluated for two fixed levels of precision (0.10 and 0.25) and results are indicated and discussed.
The use of catalysts in numerous important processes is widespread throughout the chemical and petroleum-processing industries.
Thermal analytical techniques can be used to evaluate important properties and processes associated with solid catalysts.
This paper presents examples carried out in our laboratory of the general application of TG and DSC to the acidity, activity
and regeneration of solid catalysts.
Authors:A. Araujo, V. Fernandes, A. Silva, and J. Diniz
The evaluation of the crystallinity of several samples of ALPO-11 was performed by X-ray diffraction and thermogravimetry.
Through XRD, the degrees of crystallinity of the samples were determined by the measurement of the area of the peaks at 2γ
ranging from 20.7 to 24.1 degrees. The sample that presented the largest area was considered as 100% crystalline and the areas
of the other samples were normalized in relation to this. From TG, the degree of crystallinity was determined considering
the mass loss in the temperature range from 453 to 653 K that is related to remotion of di-isopropylamine molecules used during
the synthesis procedure. The quantity of diisopropylamine on the material is proportional to the degree of crystallinity.
Authors:A. Silva, M. Souza, J. Aquino, V. Fernandes, and A. Araújo
The coke removal of HZSM-12 zeolite deactivated in the reaction of n-heptane cracking was studied by thermogravimetry using
two multiple heating rate integral kinetics models proposed by Ozawa-Flynn-Wall and Vyazovkin to obtain the activation energy
of process of thermoxidation of coke. The results obtained by both models presented excellent accordance with the related
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. Leite, L. Maia, R. Paz, E. Araújo, and H. Lira
The aim of this work was to obtain membranes from polyamide 6/montmorillonite clay nanocomposites through the phase inversion
technique. The nanocomposites and membranes from polyamide 6/montmorillonite clay were characterized by X-ray diffraction
(XRD), Scanning Electron Microscopy (SEM), Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC). Microporous
and asymmetric membranes were successfully obtained from nanocomposites and the results showed that the salts were incorporated
by intercalation between the organoclay layers and, apparently that the nanocomposites and membranes were thermally more stable
than the pure polyamide.