Biodiesel from jatropha, neem and cottonseed were produced and their compositions were analyzed using gas chromatography–mass spectroscopy. The results revealed that the jatropha, neem and cottonseed oils are reliable sources of biodiesel and are renewable, and hence have a potential to partially meet energy demands in an eco-friendly manner. The biodiesels produced from jatropha contained 91.97% methyl ester, and that produced from neem contained 70.2% methyl ester, whereas that produced from cotton contained 89.75% methyl ester.The greater proportion of prolific ester in the jatropha biodiesel is mono-saturated methyl octa-decanoate which contributes 53.44% by volume. This ester has the tendency of assigning stability to biodiesel. For neem-based biodiesel, the profile evaluation revealed that octadecanoic acid methyl ester is the dominant compound in the mixture with 54.69% by volume. For cotton, the profile revealed that the methyl octadecenoate (C₁₉H₃₆O₂) is the predominant compound in the mixture, having the highest percentage of 17.72%. The physico-chemical analyses of the three biodiesels has indicated that the three conform with the American Society for Testing and Materials (ASTM) standards for specific gravity, viscosity, acid value, cold flow properties and sulfur content, and hence are suitable for use in compression ignition engines. Statistical analyses confirmed that there was no significant difference between the experimental values of all the physico-chemical properties investigated; therefore, the experimental data is validated.

Brakes are one of the basic safety systems on a vehicle. During the operation of the vehicle, the brakes allow the vehicle to slow down, i.e., to adapt to traffic conditions or to stop, if necessary. However, in all conditions mentioned, emissions of brake wear products occur, which are very harmful to the environment because they can contain heavy metals. Working parameters of braking process are responsible for the intensity of brake wear, which can be tested in laboratory or road conditions, as well as by using modern software packages. This paper covers the basic theoretical assumptions about brake wear, as well as the materials applied in their production. The methodologies that other authors have come up with in their research are shown in this paper. Those methodologies are related to testing the brake wear, the parameters which are the most influential on wear, as well as the measures for the reduction of brake wear. The available scientific literature in the subject area lead us to the conclusion what should be taken into the consideration in future research and what factors are not thoroughly investigated, all with the aim of reducing the emission of brake wear.