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.

Berries are a large and economically very important group of fruit. Serbia is not at the top in the production of this fruit, but is at the top in exported quantities of berries. Almost the total amount of berries are exported in frozen condition. The aim of this study was to analyze the influence of freezing process on the quality and sensory characteristics of berry fruit. Investigation were carried out with the strawberry, raspberry and blackberry fruits. Within the sensory quality analysis, special emphasis is placed on maintaining the strength and color of these delicate fruits. As quality parameters, content of total sugar and acid, dry matter content and pH values of berry fruits were analysed. The content of vitamin C in the berries, before and after process of freezing, were determined. The obtained results showed that there was no significant changes in chemical quality parameters. Somewhat larger changes was in sensory characteristics, as determined by the loss of strength and consistency, especially in strawberry fruit.

The aim of present research was to establish the role of epicuticular wax content in eight cabbage genotypes (four white hybrids and one red hybrid, two red varieties and one white variety) in the context of its natural resistance to attack cabbage flea beetles (Phyllotreta spp.) and cabbage stink bugs (Eurydema spp.), which are among the most important cabbage pests in southern Europe. For this reason and for the purpose of diminishing the use of synthetic insecticides against the cabbage pests the field experiments in 2006 and 2008 were conducted. We found out that individual cabbage genotypes – they had different epicuticular wax content – differ in regard to their susceptibility to attacks by the studied groups of harmful insect pests. The highest susceptibility to attacks by Phyllotreta spp. was confirmed for the hybrid ‘Cheers F1’, in the first year (1.68 ± 0.05), as well as in the second year of the experiment (2.87 ± 0.13). Cabbage stink bugs in both years of the experiment caused the highest extent of injuries on the hybrids ‘Destiny F1’, ‘Cheers F1’, and ‘Vestri F1’. In both years we found higher epicuticular wax content in red cabbage genotypes. In almost all studied genotypes we found a pronounced negative correlation between the content of epicuticular wax and the extent of injuries done by both groups of harmful pests. We have established that epicuticular wax is an important factor of cabbage's antixenotic resistance to attacks by cabbage flea beetles and cabbage stink bugs, and that the cabbage genotypes with higher content of this substance are consequently more suitable for environmentally acceptable manners of cabbage production.

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.