Pyrolytic degradation of peanut shell: Activation energy dependence on the conversion.

This study focuses on the thermo-kinetic analysis of solid peanut shell waste, through dependence of the activation energy with the conversion degree. Three model-free kinetics, Kissinger (K), Friedman (Fr) and Kissinger-Akahira-Sunose (KAS), were applied to thermogravimetric (TGA) data to calculate the effective activation energy Eα during a pyrolysis process. The results obtained by Kissinger's method showed that the pyrolytic breakdown pathway of hemicellulose, cellulose, and lignin in a ligno-cellulosic biomass is independent of the heating rate and can be described through a simple first-order kinetic reaction (f(α) = 1 - α). The thermo-kinetic behavior obtained by isoconversional methods (Fr and KAS) of the hemicellulose degradation shows a progressive and monotonic increase in Eα with the conversion, between ~140 and ~195 kJ mol-1 with an average value of 172 kJ mol-1, which reveals the competitive character of the process (multi-step process). Conversely, in the cellulose degradation, the dependence of Eα on α, shows the typical behavior of a reaction controlled by a single rate-determining step, with constant average Eα values of ~209 kJ mol-1. Meanwhile, the lignin pyrolytic degradation shows an increase in Eα from ~220 up to ~300 kJ mol-1 with the conversion, indicating that this stage is kinetically controlled by an energy barrier that comprises multiple and simultaneous processes. Finally, the kinetic analysis confirmed the absence of autocatalytic reactions (thermally auto-catalyzed process) during the pyrolysis, although the global process is highly exothermic.

Dose per unit cumulated activity (S-values) for e⁻ and beta emitting radionuclides in cancer cell models calculated by Monte Carlo simulation.

Cell dosimetry is relevant regarding new efforts in specific molecular radiotherapy using Auger, CE and beta emitters. Absorbed dose in cells can be obtained by means of the dose per unit cumulated activity (S-values), together with the activity distribution. In this work, Monte Carlo simulation codes PENELOPE and MCNPX were used to obtain cellular S-values for point and extended sources of electrons and beta emitting radionuclides in the nucleus of breast (MDA-MB231, MCF7) and prostate (PC3) cancer cell models.

Gender differences and regionalization of the cultural significance of wild mushrooms around La Malinche volcano, Tlaxcala, Mexico.

The purpose of this study was to determine the cultural significance of wild mushrooms in 10 communities on the slopes of La Malinche volcano, Tlaxcala. The frequency and order of mention of each mushroom species in interviews of 200 individuals were used as indicators of the relative cultural significance of each species. A X(2) analysis was used to compare the frequency of mention of each species between males and females, and a Mann-Whitney U test was used to compare the difference in the total number of fungi mentioned by either gender. Traditional names for mushroom species were documented and frequency of mention assessed through multivariate statistics. The fungi with highest frequency of mention were Amanita basii, Lyophyllum decastes, Boletus pinophilus, Gomphus floccosus and Cantharellus cibarius complex. We found significant differences in the frequency of mention of different fungi by males and females but no significant difference was found for the total number of fungi mentioned by either gender. Principal component analysis suggested a cultural regionalization of La Malinche volcano communities based on preferences for consumption and use of traditional names. We observed two groups: one formed by communities on the eastern part of the volcano (with mixed cultures) and the other including communities on the western slope (ethnic Nahua towns). San Isidro Buensuceso is the most distinct community, according to the criteria in this study.

Monte Carlo microdosimetry of 188Re- and 131I-labelled anti-CD20.

The radiolabelled monoclonal antibody anti-CD20 has the property of binding to the CD20 antigen expressed on the cell surface of B-lymphocytes, thus making it a useful tool in the treatment of non-Hodgkin's lymphoma. In this work, the event-by-event Monte Carlo code NOREC is used to calculate the single-event distribution function f(1)(z) in the cell nucleus using the beta spectra of the (188)Re and (131)I radionuclides. The simulated geometry consists of two concentric spheres representing the nucleus and the cell surface embedded in a semi-infinite water medium. An isotropic point source was placed on the cell surface to simulate the binding of the anti-CD20 labelled with either (188)Re or (131)I. The simulations were carried out for two combinations of cell surface and nucleus radii. A method was devised that allows one to calculate the contribution of betas of energy greater than 1 MeV, which cannot be simulated by the NOREC code, to the single-event distribution function. It is shown that disregarding this contribution leads to an overestimation of the frequency-mean specific energy of the order of 9-12%. In general, the antibody radiolabelled with (131)I produces single-event distribution functions that yield higher frequency-mean specific energies.

Síndrome neuroléptico maligno inducido por olanzapina / Olazapine induced neuroleptic malignant syndrome

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