This paper shows the use of membrane filters in adsorption of solution of tetracycline hydrochloride on graphene materials. The adsorption process was monitored at different wavelengths, different pH values at certain time intervals. The absorbances of the solutions were measured by UV-Vis spectrophotometry at two wavelengths (275 nm and 356 nm), and three pH values (pH 4, pH 7 and pH 10) every 90 minutes for 6 hours of monitoring, with constant stirring in an ultrasonic bath. The results showed decrease in absorbance at both wavelength and in all three pH values which proved the adsorption of tetracycline hydrochloride on GO and rGO. The largest decrease in absorbance was 98.1%. The most suitable pH value for adsorption was pH 4. This paper used a unique approach to filtration through membrane filters, which in the future could lead to the development of membrane filters based on graphene materials.

Every citizen of the Republic of Serbia has another opportunity to invest and increase their income - investment funds. The first funds began its operations shortly after adoption of the Law on Investment Funds in 2006 which provided legal framework for their establishment and doing business. The initial years of business were marked with negative influences as a result of great crisis within world markets. The main reasons for limitation of greater investment of individual investors in investment funds are both low standard and financial status of citizens of Serbia, underdeveloped national economy, underdeveloped financial markets and consequently, low and negligible investment funds' income.

In a two-year field experiment, we studied the extent of damage caused by cabbage stink bugs (Eurydema spp.) on the frame leaves and the outer leaves of cabbage heads in relation to genotype color. We established that the extent of damage varied with genotype color. In both years of the experiment, the affinity of Eurydema spp. toward green genotypes was significantly greater on the first four assessment dates (from the third decade of May to the third decade of June), while on the remaining dates (from the third decade of July to the second decade of August) we did not establish any differences between the white and red genotypes. Cabbage stink bugs first appeared on white cabbage genotypes. The antioxidative potential conditioned by the content of anthocyanins was significantly higher on the red cabbage genotypes. Research shows that higher antioxidative potential is related to a lower extent of damage caused by Eurydema spp. The average value of antioxidative potential in the cabbage varieties was 0.58 mmol/100 g of the sample, while in the hybrids it was 0.47±0.01 mmol/100 g. We confirmed significant differences in values of antioxidative potential between red (0.68 mmol/100 g) and white (0.48 mmol/100 g) cabbage genotypes. Between mid-late (0.55 mmol/100 g) and mid-early (0.53 mmol/100 g) cab- bage genotypes we did not establish differences in antioxidative potential levels, while the average value of this parameter in the early genotypes (0.46 mmol/100 g) was significantly low. We established that the color of plants (cabbage) represents one of the successful factors of antixenosis and has the potential for reducing the damage caused by cabbage stink bugs in environmentally acceptable systems of cabbage production.