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  • Author or Editor: G. Mendez x
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Abstract  

Bisphenol-A polycarbonate (BAPC) was crystallised by exposure to acetone vapours for a period of 9 h; it developed a 20% crystallinity according to WAXS measurements. The samples of semi-crystalline BAPC were then submitted to a series of thermal treatments including annealing, self-nucleation and subsequent isothermal crystallizations. The results showed that the polymer possesses a remarkable crystalline memory and a much faster recrystallization and reorganization capacity (lamellar thickening) than its very low thermal crystallization rate. This peculiar crystallization behaviour probably stems from its rigid backbone molecular structure.

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Abstract

The main objective of the present study is to study the behaviour of sewage sludge and biochar from sewage sludge pyrolysis after addition to soil in a context of a temperate agricultural soil. For this, an incubation experiment was designed during 200 days. Carbon mineralization of soil amended with sewage sludge and biochar at two different rates (4 and 8 wt%) was evaluated. Differential thermal analysis, thermogravimetry and the first derivate of the TG were performed in oxidizing conditions on soil samples before and after incubation. Biochar obtained from sewage sludge pyrolysis at 500 °C was more stable in soil than original sewage sludge. After incubation experiment, the reduction of soil organic matter content was significantly lower in soil amended with biochar than in soil amended with sewage sludge. The thermostability index WL3/WL2 decreases after incubation in soil amended with biochar, however it increases in case of soil treated with sewage sludge.

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Abstract  

This study is an analysis of six years of Spanish bibliography retrieved from INSPEC and COMPENDEX. The quantitative evolution of the scientific activity by years and Institutions, the recent tendencies to publish in foreign journals, as well as to have the papers signed by more authors are followed. The most frequently used journals are ranked according to their impact factor and subject. Some hypothesis are formulated and tested, trying to find a relationship between the growth of the Spanish scientific activity and its quality.

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Abstract

This study deals with thermal analysis of growing media obtained from mixtures of paper will waste materials (one de-inking paper sludge, HP, and one reject from paper mill producing paper from virgin wood, RT) with sewage sludge. For the growing media formulation, one sewage sludge (L) was mixed with both paper mill waste materials at 10, 20, and 30% in volume. An incubation experiment was designed in order to study their carbon mineralization. Addition of sewage sludge significantly increases the carbon mineralization of growing media based on RT. In case of HP, carbon mineralization increases after addition of sewage sludge in 30% (HP + 30L treatment). Thermogravimetric analysis (TG and DTG) of growing media was performed before and after incubation experiment in order to study the organic matter transformation. The higher the carbon mineralization, the greater the difference between TG curves of samples before and after the incubation. The WL3/WL2 ratio increases after incubation of samples as a result of organic matter stabilisation. For HP growing media, the highest value corresponds to HP + 30L whereas HP + 20L, and HP + 10L show similar values. In case of RT, the WL3/WL2 index shows a progressive increase with sewage sludge content.

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Pleurotus djamor from Yucatan State, Mexico was compared with a local variety of P. ostreatus , in terms of chemical composition and amino acid profile. No differences were found (P=0.55) in crude protein content of P. djamor and P. ostreatus (20.2±0.15 vs. 20.3±0.16 g/100 g DM., respectively). P. ostreatus had a lower fiber and fat content (P<0.05). No difference was found in ash content (P>0.05). P. ostreatus has a higher proportion (P<0.05) of valine, isoleucine, phenylalanine, aspartate and alanine while P. djamor had higher proportion (P<0.05) of proline and glutamate, no difference was found in the remaining amino acids. Both species had a high proportion of aspartate and glutamate. In general, the human amino acid requirements for adults are satisfied, however, leucine and lysine might become limiting. It was concluded that P. djamor can be included in human diet in similar fashion as P. ostreatus .

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Marinated chicken meat is an ideal substrate for the growth of microorganisms. The aim of this study was to determine the effect of high-intensity ultrasound on the microbial flora of chicken meat marinated in oregano oil. Three concentrations of oregano oil (0%, 0.1%, and 0.3%) and two types of marination (traditional and highintensity ultrasound) were tested. Microorganisms were enumerated immediately after marination and on 7, 14, and 21 days of chilled storage. Marination in oregano oil resulted in significant differences (P<0.05) in the numbers of anaerobic, lactic acid bacteria, and mesophiles. Ultrasound with 0.1% OEO did not show any effect on the three types of bacteria. The treatment with 0.3% oregano oil and ultrasound had the greatest effect on controlling microbial growth. Therefore, a combination of ultrasound and oregano oil is the most appropriate option for reducing the growth of mesophilic, anaerobic, and lactic acid bacteria in vacuum-packed marinated chicken breasts during chilled storage.

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