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Allelopathy defines the production of specific biomolecules (allelochemical) by a plant that can induce positive or negative impacts on another culture. The crop of castor beans ( Ricinus communis L.) is being economically valued and receiving attention, mainly by the biodiesel production, castor oil and animal feeding. In this study, the allelopathic effect of aqueous extract from fresh leaves of castor beans ( Ricinus communis L.) applied to the beginning stage of soy ( Glycine max L.) and of safflower ( Carthamus tinctorius L.) was investigated. An experimental was setup with five blocks and four replications, considering that each block refers to a concentration of extract of castor beans fresh leaf (0, 25, 50, 75 and 100%); the one without castor beans leaves was taken as ‘witness’. The statistic treatment was done using analysis of variance (ANOVA) and Tukey test with an error rate of 5%. The result showed evidences that there are allelopathic effects among the extract of castor beans fresh leaf and the beginning stage of soy and safflower only in the root part of the seedling. Key words: Ricinus communis L., Glycine max L., allelopaty.

One of the main fuels that can be helpful in emissions reduction when compared with diesel oil is the biodiesel. Moreover, it is a renewable fuel and may be obtained from different animal fat and vegetable oil. The purpose of this work was to evaluate fuel specific consumption and emission of exhaustion gases using the biodiesel produced from waste frying oil in a cycle diesel internal combustion engine (ICE) to produce electrical energy. The used motor generator has a power of 7.36 kW (10 HP) and 5.5 kVA /5.0 kW of nominal power. The used fuel was composed of a biodiesel and diesel oil blend and the following proportion in biodiesel composition was used: 0% (B0), 5% (B5), 10% (B10), 20% (B20), 50% (B50) and 100% biodiesel (B100). The nominal load applied varied between 0.5 and 5.0 kW. The analysis test was just performed with (B0) and (B100) blends. To quantify the gases emission, combustion and emission analyzer were used. The quantified gases were: CO, NO, NOx and SO 2 . Generally, the utilization of biodiesel from waste frying oil showed fuel specific consumption statistically similar to that of the diesel oil. It was observed that the biodiesel from waste frying oil provided an emission reduction of combustion gases. Key words: Combustion, energy production, biofuel.

This work allows the thermodynamics, thermoeconomic and economic analysis of the cogeneration system of an industrial plant. Two settings were studied: the current that produces electricity only for its own, and secondary, a plant working at high pressure and high temperature using extraction steam turbines to drive an electricity generator and produce 32 MW and a backpressure turbine capable of producing 12 MW. In this case, a high investment is necessary and therefore, a considerable amount of energy sales. The thermodynamic analyses allow the evaluation of some performance indices. The thermoeconomic analysis proposes the distribution of costs based on thermodynamic concepts, enabling the evaluation of reflection of the investment costs and fuel in the cost of products (steam and electricity). The economic analysis acts as a deciding factor for acceptance or project rejection.Keywords: Cogeneration, economic, thermodynamics, thermoeconomic.African Journal of Biotechnology, Vol 13(30)