Oxidized starch, an additive used in paper manufacturing and products for construction industry, is usually produced using harmful oxidant, such as hypochlorites or periodates. In this study, a simple and efficient eco-friendly laboratory and industrial procedures for starch oxidation were developed. The procedure involves application of small amounts of more environmentally friendly oxidant, hydrogen peroxide, a novel special metal complex catalyst such as copper(II) citrate and copper(II) ricinoleate and biobased plasticizers. Optimization procedure, with respect to the quantity of hydrogen peroxide and temperature in the presence of iron(II) sulphate catalyst, was performed by using the response surface methodology. Comparative analysis of the use of the other catalysts that is copper(II) sulphate, copper(II) citrate and copper(II) ricinoleate, indicated copper(II) citrate as the catalyst of choice. Improvement of starch is achieved using three plasticizers: ricinoleic acid (RA), diisopropyl tartarate, as well as epoxidized soybean, linseed and sunflower oils. The effects of hydrogen peroxide and catalyst concentrations, as well as the reaction temperature in the presence of naturally based plasticizers on the physicochemical, thermal and morphological properties of oxidized starch are presented. According to the results obtained in initial experiments, the optimal industrial process is based on the use of copper(II) citrate (0.1 %) as a catalyst and RA (3 %) as a plasticizer.

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Teaching physics in primary and secondary schools is realized through classic lecturing in classes of about 30 students, individual examinations, written tests and assignments and laboratory exercises. Knowledge is transferred from teachers to students mostly in its final form, which is not motivating for students or their teachers to develop and construct knowledge actively. A good way to overcome this problem is active teaching/ learning through application of cooperative form of learning, where the aim is that students study through interaction which they enter on the basis of their previous knowledge and skills and to become active creators of their knowledge. This study presents a research survey with the aim to establish effects of cooperative learning of physics and music as well as physics and art in secondary schools. The surveys we conducted show that this approach to teaching contributes to a higher level of understanding, better transfer of knowledge, better achievement and also to the inner motivation of both students and teachers. The obtained results indicate that cooperative learning can be applied to students of all ages, for all school subjects and within a large number of themes.

Economic and social development of cities, as well as the development of transport, yield great benefits to the inhabitants, but also have rather negative impact on the environment. The paper analyzes the results of environmental monitoring of air quality in the municipality of Trstenik for 2017, based on the assessment report done by the Public Health Institute Kruševac (an accredited testing laboratory of the municipal administration of Trstenik). Sampling was performed at a measuring site in Trstenik over a 24-hour period. Afterwards, an analysis of the obtained measurement results was carried out, followed by a conclusion on air pollution values, and a proposal for improvement measures.

The paper presents an application of the big data analytics process on a data extracted from the educational system for online testing. The procedure of data migration to a non-relational system was implemented. Big data analytics process was realized through query processing in MongoDB and analysis results visualization in Microsoft Power BI. The contribution of the research presented in this paper refers to the importance of applying the big data concept for analyze data set extracted from educational systems in order to discover information and knowledge important for improving the efficiency of the educational process.