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Hydrogels are attractive materials for drug delivery applications due to biocompatible, porous structure with the possibility to load and deliver drugs in a controllable manner. In this paper, poly(methacrylic acid) (PMAA) hydrogels are described, which are synthesized by free-radical polymerization, using poly(ethylene glycol) diacrylate (PEGDA) as a crosslinker. Influence of the PEGDA content on hydrogel properties was investigated and compared to commonly used crosslinker - N,N’-methylenebisacrylamide (MBA). The increasing concentration of crosslinkers led to a higher degree of crosslinking, which was demonstrated by a higher degree of conversion, lower swelling capacity, and improved thermal stability and mechanical properties. Also, the PEGDA-crosslinked hydrogels demonstrated a higher degree of crosslinking than the corresponding MBA-crosslinked hydrogels. Potential application of the synthesized hydrogels for controlled drug delivery was investigated by using two model drugs - oxaprozin and ciprofloxacin. In vitro drug release tests indicated that the interactions between drug, polymer and medium have a key influence on the drug release behavior, rather than the swelling rate. Drug release tests in simulated gastrointestinal conditions indicated that PEGDA-crosslinked PMAA hydrogels are suitable for colon-targeted delivery of oxaprozin.

The contemporary phase of marketing development emphasizes the increasingly important role of economic entities as an integral part of society and a catalyst for positive changes. Researchers mainly focus their attention on large companies and sectors that significantly impact the local community and society. In that sense, this article addresses the Serbian banking sector. The authors analyzed the corporate social responsibility activities of 24 banks and their reporting practices. The analysis included a study of the content of publicly available documents and reports and news published on banks' websites and Facebook profiles. In addition, the authors explored stakeholders' perceptions of socially responsible banking activities. A survey of 30 banks stakeholder representatives showed: what are the critical issues in local communities; what are the respondents' attitudes about banks and the way they operate in Serbia; to what extent have stakeholders noticed the social marketing activities of commercial banks; what is the attitude of stakeholders regarding the issue of rewarding banks for socially responsible behavior. After reviewing and discussing the main findings, the authors provide key recommendations and possible directions for further research.

The contemporary phase of marketing development emphasizes the increasingly important role of economic entities as an integral part of society and a catalyst for positive changes. Researchers mainly focus their attention on large companies and sectors that significantly impact the local community and society. In that sense, this article addresses the Serbian banking sector. The authors analyzed the corporate social responsibility activities of 24 banks and their reporting practices. The analysis included a study of the content of publicly available documents and reports and news published on banks' websites and Facebook profiles. In addition, the authors explored stakeholders' perceptions of socially responsible banking activities. A survey of 30 banks stakeholder representatives showed: what are the critical issues in local communities; what are the respondents' attitudes about banks and the way they operate in Serbia; to what extent have stakeholders noticed the social marketing activities of commercial banks; what is the attitude of stakeholders regarding the issue of rewarding banks for socially responsible behavior. After reviewing and discussing the main findings, the authors provide key recommendations and possible directions for further research.

Supercapacitors are the best choice when there is a need to deliver high power to the consumer or to store energy. Hybrid supercapacitors with their beneficial characteristics can somewhat overcome the basic lack of batteries, that is the low power density, and when supercapacitors are combined with batteries, the current maximum power can be increased and the lifetime extended. The number of research studies on development of new materials and construction technologies for supercapacitors has been increasing steadily in recent years. As a result, production of commercial devices and their applications are constantly growing, with improved product properties. Here we present the current state of development of supercapacitors as highly promising energy storage systems by an overview of operation principles, main components and various electrode materials and electrolytes, as well as description of different modes of production. A special attention was paid to the need of a good match of the active material and electrolytes, in order to achieve high capacity of the device. The electrode/electrolyte phase optimization is the key to maximizing characteristics of a supercapacitor, especially the capacitance. In selecting the materials, requirements of the final application must be considered, such as the specific energy and power, energy and power density, and service life-time. In addition to material selection, design and optimization of the cell configuration provide new opportunities for development of hybrid battery/supercapacitor systems. Demand for such systems will increase in future, when using a battery or a supercapacitor alone will not be able to meet specific needs, such as the energy density, number of charge and discharge cycles or voltage. Finally, equally important as the development of materials and cells, are the electrode production technology and the cell construction, which need to be optimized in order to improve supercapacitor properties. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172060: Nov pristup dizajniranju materijala za konverziju i skladištenje energije, kao i bilateralnog projekta Srbija Hrvatska: Superkondenzatori visoke snage zasnovani na grafen/pseudokapacitivnim materijalima]

Goals. The goal of this study was a development of biocompatible composite hydrogels, structurally similar to native bone tissue, by incorporation of ~60 wt % of calcium hydroxyapatite (HA) into a matrix of hydrogels. Also, a possibility to control swelling kinetic and equilibrium swelling degree (SDeq) of hydrogels, by altering the degree of neutralization of the precursor (DN) was examined. Methods. Composite hydrogels, based on HA and poly(methacrylic acid) (PMAA), were synthesized by free-radical polymerization with different DN. Theoretical content of HA in synthesized composites was 60 wt %. Composites were synthesized by methods of dynamic mechanical analysis and scanning electron microscopy. SDeq and swelling kinetic were examined in distilled water and simulated body fluid. Results. Morphological observations revealed uniform distribution and strong bond of spherical HA particles within the polymer matrix. Swelling analyses demonstrated that SDeq is directly proportional to DN, while rheological examinations indicated inverse proportion between DN and storage modulus, but due to the HA particles inclusion, mechanical properties of composites were significantly better compared to monophasic PMAA hydrogels. Significance. Simple method of synthesis of composite hydrogels with high content of filler nanoparticles is presented. Incorporation of HA nanoparticles significantly improved mechanical properties of hydrogels, while at the same time was demonstrated a possibility to control swelling kinetic by influencing the DN.

The use of polymeric adsorbents for the removal of azo dyes from solution has been reviewed. Adsorption techniques are widely used to remove certain classes of pollutants from waters, especially those which are not easily biodegradable. The removal of azo dyes as pollutants from wastewaters of textile, paper, printing, leather, pharmaceutical and other industries has been addressed by the researchers. The wider use of already available adsorbents is restricted due to their high costs which lead to investigation and development of new materials that can be cheaper, eficient and easy regenerated. The aim of this article is to present to the readers the widespread investigations in recent years of synthetic and natural polymers as adsorbents and potential replacement of conventional adsorbents. This review presents only the data obtained using raw, hydrogel, grafted and crosslinked forms of synthetic and nature based polymers, and the discussion is limited to these polymer-based materials and their adsorption properties. [Projekat Ministarstva nauke Republike Srbije, br. 43009 i br. 172062.]

The influence of different parameters (forced hydrolysis duration in the preparation of sols, alcohol addition in the sol mixture for application, as well as sol/alcohol mixture ageing time) on the morphology and electrochemical properties of RuO2-TiO2 coatings obtained by the sol-gel procedure is presented. The oxide sols were sharacterized by spectroscopic and microscopic methods (X-ray diffraction, TEM, etc). The morphology of the obtained coatings was examined by scanning tunneling microscopy, while the electrochemical properties were investigated by cyclic voltammetry polarization measurements, electrochemical impedance spectroscopy and the accelerated stability test. The greatest real surface area was obtained for coatings with the smallest RuO2 particles and largest TiO2 particles. Alcohol addition caused enlargement of the oxide grains and, consequently, a decrease in the real surface area. The same effects of oxide grain size were registered on electrochemically active surface area. The electrocatalytic activity of the obtained anodes for the chlorine evolution reaction increased with growth of the TiO2 particles, but depended on the RuO2 particle size to a small degree. The corrosion stability of the anode coatings consisting of the smallest RuO2 particles and largest TiO2 particles whis the greatest in the electrolysis of a sodium-chloride solution.