Considering the serious impact caused to the environment by the inappropriate disposal of waste motor oils, it is essential to find alternative mechanisms to handle and dispose these wastes in a controlled process. The reuse of waste motor oil as a resource for the synthesis of diesel-like fuels provides an alternative way for the disposal of this residue in a feasible, sustainable, and environmentally responsible way. This work addresses the kinetic study of the catalytic cracking of waste motor oil using mesoporous aluminum silicate materials impregnated with 1 and 2% zinc. Both the waste motor oil and liquid fuel product were characterized according to ASTM standards to ensure an adequate characterization and to guarantee the proper quality of the product. The results from the overall kinetic approach show that the cracking reaction can be described using a first-order rate equation with respect to the concentration of the used motor oil. The activation energy for the thermal cracking reaction is 370 kJ/mol. It is reduced by 22% to 287 kJ/mol when the alumina silicate catalysts are used. Also, during the reaction, the overall yield of the reaction with respect to the liquid fuel is increased from 63% during the thermal reaction to 90% during the catalytic reaction.

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The guinea pig (Cavia porcellus) is a species of social and cultural importance in the southwestern region of Colombia. However, information on zootechnical variables is under development. The objective of this work was to identify the behavior of lines, productive and reproductive variables of guinea pigs in Nariño and Putumayo. A survey was applied in 404 productive systems of the municipalities of Pasto-Nariño and Colón, San Francisco, Santiago and Sibundoy-Putumayo. The data were processed in the program IBM-SPSS-Statistics® V. 20.0-2011. The distribution of lines corresponded to crosses: Criolla-Peru-Andina 61.4%, Criolla-14.8%, unidentified line 13.4%, Peru 9.65% and Andina 0.74%. The age at first mating (months) was lower for the Peruvian (5.1) and Andean (4.5) lines than in Creole animals (5.3). The number of births/ females/years in the Peruvian and Andean lines was 3.7 in Creole females was 3.4. The 97.3% of the producers have established groups of mount where the relation male: females, by lines was of 1:6, 1:8 and 1:4 for Criolla, Peru and Andina respectively. The average weights (g) at birth, weaning and benefit were: 222, 413 and 1330 (Criolla), 197, 390 and 1259 (Peru) and 125, 450 and 1300 (Andina) respectively. The age at weaning (days) was 24.5 (Criollos), 19.3 (Peru) and 18.3 days (Andina). It was evidenced predominance in the use of Creole lines and/or crosses. The Peruvian and Andean lines reported greater reproductive efficiency, the Creole race presented a greater productive efficiency. Due to the potential of the system, it is pertinent to carry out a broader characterization.

This paper describes a new set of experiments focused on estimating time series of the free surface elevation of water (FSEW) from velocities recorded by submerged air bubbles under regular and irregular waves using a low-cost non-intrusive technique. The main purpose is to compute wave heights and periods using time series of velocities recorded at any depth. The velocities were taken from the tracking of a bubble curtain with only one high-speed digital video camera and a bubble generator. These experiments eliminate the need of intrusive instruments while the methodology can also be applied if the free surface is not visible or even if only part of the depth can be recorded. The estimation of the FSEW was successful for regular waves and reasonably accurate for irregular waves. Moreover, the algorithm to reconstruct the FSEW showed better results for larger wave amplitudes.

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Cellulose pyrolysis is reportedly influenced by factors such as sample size, crystallinity, or different morphologies. However, there seems to be a lack of understanding of the mechanistic details that explain the observed differences in the pyrolysis yields. This study aims to investigate the influence of particle size and crystallinity of cellulose by performing pyrolysis reactions at temperatures of 673–873 K using a micropyrolyzer apparatus coupled to a GC × GC-FID/TOF-MS and a customized GC-TCD. Over 60 product species have been identified and quantified for the first time, including water. Crystalline cellulose with an average particle size of 30–50 × 10–6 m produced 50–60 wt % levoglucosan. Predominantly amorphous cellulose with an average particle size of 10–20 × 10–6 m resulted in remarkably low yields (10–15 wt %) of levoglucosan complemented by higher yields of water and glycolaldehyde. A detailed kinetic model for cellulose pyrolysis was used to obtain mechanistic insights into the different pyrolysis product compositions. The kinetics of the mid-chain dehydration and fragmentation reactions strongly influence the total yields of low-molecular weight products (LMWPs) and are affected by cellulose chain arrangement. Levoglucosan yields are very sensitive to the activation of parallel cellulose decomposition reactions. This can be attributed to the mid-chain reactions forming smaller chains with the levoglucosan ends, which remain in the solid phase and react further to form LMWPs. Direct quantification of water helped to improve the description of the dehydration, giving further indications of the dominant role of mid-chain reaction pathways in amorphous cellulose pyrolysis.

Objetivo: El propósito de este estudio fue desarrollar un cemento de policarboxilato partiendo de la reacción de neutralización del poli (ácido acrílico) con fluoruros de cobalto en presencia de óxidos metálicos. Materiales y métodos: La preparación del policarboxilato de cobalto (CoPA) comprendió la síntesis del poli (ácido acrílico) (PAA) para la cual se utilizó ácido acrílico (J.T. Baker), persulfato de amonio (J.T. Baker), alcohol isopropílico (J.T. Baker) y agua desionizada. Estos reactivos fueron colocados en un reactor de vidrio (70 °C ± 5 °C) con agitación constante en una atmósfera de nitrógeno y se calculó el peso molecular viscosimétrico. Para las reacciones de neutralización se usaron el PAA sintetizado en el laboratorio, fluoruro de cobalto III (CoF3) (J.T. Baker), fluoruro de cobalto II (CoF2) (Aldrich) y material de relleno (polvo) sintetizado en el Laboratorio de Materiales Dentales (DEPeI, F.O. UNAM), y se midieron tiempos de trabajo y fraguado, resistencia compresiva y erosión ácida de acuerdo a la norma ADA 96. Resultados: Los pesos moleculares viscosimétricos del PAA sintetizados fueron de 8,000 y 40,000 g/mol. En los resultados de tiempo de trabajo, tiempo de fraguado, resistencia a la compresión y erosión ácida se encontraron diferencias estadísticamente significativas cuando se analizaron con ANOVA (p < 0.001) y prueba de Tukey (p < 0.05). Conclusiones: Los valores más cercanos a los establecidos por la norma se obtuvieron con PAA 40,000 g/mol, CoF2 y material de relleno sintetizado