Biodiesel from different mixtures of animal fat and soybean oil has been synthesized, and its properties have been evaluated and related to its composition. A mixture of 50 vol % of both raw materials has been selected as a suitable feedstock for industrial biodiesel production, and a computer simulation of the production process using Aspen Plus software has been carried out to evaluate the industrial feasibility of this scheme using this cheaper feedstock. The results obtained suggest that the process proposed and described produces a biodiesel with the selected feedstock acceptable by the standards with a lower final cost. The feedstocks employed are cheaper and consist of a waste fat without any other use, thus increasing the environmental benefits of the biodiesel and reducing dependency on conventional agricultural raw materials.

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The recruitment period of Locariichthys platymetopon (Isbrucker & Nijssen, 1979) was investigated. It has been found out, through the data analysis, that the gonadal condition factor is a good indicator of the reproductive period and that the hepatossomatic index is probably related to the storage of reservation for the winter period. The recruitment occurred in November coinciding with the reproductive activity of May.

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A visual basic application for Microsoft Excel 2007 has been developed as a helpful tool to perform mass, energy, exergy and thermoeconomic (MHBT) calculations during the systematic analysis of energy processes simulated with Aspen Plus®. The application reads an Excel workbook containing three sheets with the matter, work and heat streams results of an Aspen Plus® simulation. The required information from the Aspen Plus® simulation and the algorithm/calculations of the application are described and applied to an Air Separation Unit (ASU). This application helps the designer when MHBT analyses are performed, as it increases the knowledge of the process simulated with Aspen Plus®. It's a valuable tool not only because of the calculations performed, but also because it creates a new Excel workbook where the results and the formulae written on the cells are fully visible and editable. There is free access to the application and it has no protection allowing changes and improvements to be done.

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Keywords: XRF ICP-AES Trace elements Mining SulphidesLinares (Jaen, Spain) has been subjected to an intense mining and metallurgic activity during 2500 years. Basically, lead and silver have been extracted from galena; as well as copper and zinc. Different studies have been conducted to evaluate trace element concentrations to obtain relationships with anthropogenic and geologic factors. The analytical results of these studies have been obtained with ICP-AES. This analytical technique is relatively expensive and inaccessible in zones with scarce economic means. In this study, XRF analyses have been conducted and the obtained results are presented, as well as a comparison with the previously obtained ICP results. In both cases, a cluster analysis has been made to try to identify the same relations in the target area. 5 groups have been identified, mainly related with lithology. Only 10 of the 122 grid squares (each one of 1 km 2 ) are classified in different groups if the cluster analysis is conducted with XRF results or ICP results. ICP classifies better where these grid squares are located, mostly, in contact zones of different lithologies.