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.

The aim of this paper is to analyze the relationship between the Fund for Social Security of Military Insurers and the Republic Health Insurance Fund through the aspect of more efficient use of health insurance funds. Analyzing this relationship, the system of health care in the Republic of Serbia and the health insurance system are essentially considered. Taking into account the specifics of the social protection of military insurers, efforts are being made to find out the direction and improvement of relations with the civilian health care system. Only the proactive relationship between the military and the civilian health system and the health insurance system is a condition of better health care for the insured of both funds, as well as more efficient use of health insurance funds. Health protection of the population is one of the most important social priorities and as such it must be given special attention. The right of the individual to health care, but also to other forms of protection, is realized within the framework of social insurance. Health care, and therefore the health insurance system of military insureds, developed in accordance with the specifics related to the military system itself. Fully respecting the autonomy of the said system, the development of insurance in this area evolved along with changes in the prevailing civilian health insurance system. The system of health care and health insurance is one of the most important systems in each country. The efficiency and cost-effectiveness of the functioning of this system is a challenge for every national economy. The goal that needs to be achieved is to achieve the best health care of the nation by means of available health insurance. The system of compulsory health insurance in the Republic of Serbia is implemented through a unique state organization - the Republic Health Insurance Fund. When it comes to health insurance and the protection of civil and military insurers, it is clear that these are two completely separate and independent systems that have a lot of common points and whose mutual cooperation and shared use of resources should lead to positive effects as a whole. The financial aspect, which is especially reflected through the health insurance system, is one of the most important factors because it directly affects the scope and quality of the entire health care system. Considering and analyzing the complexity of the mutual relations between the civilian and military health and social security systems, and consequently the health care system, some of the possible proposals have emerged for improvement of one of the most important aspects of every society - the health of the nation.

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.