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Polymer composite films of tris-(8-hydroxy-quinoline) aluminum (Alq3) and polymethyl methacrylate (PMMA) at two different concentrations were investigated. Dielectric properties of the samples were measured in broad frequency range and results show an increase in specific conductance and susceptance by adding Alq3 in PMMA. Changes in dielectric spectra caused by irradiation of the samples with LED lamps at different wavelengths were also recorded. The samples were examined by UV–Vis and Fourier transform infrared spectroscopy. The interaction between Alq3 and the polymer matrix was observed in the photoluminescence spectroscopy spectra. The doping of the PMMA with different concentrations of the Alq3 leads to the unique photodielectric properties of the resulting composite, and that is the main result of this study. Due to its interesting optical and photodielectric properties, PMMA/Alq3 film may find application in solar cells and optoelectronics.

The purpose of this paper is to make a research on solar power plants integration in an electric power system, taking into account all costs arising from circular economy criteria. Four scenarios of solar power plant installation are analyzed. The methodology relies on nature-inspired optimization. The evolutionary multiobjective genetic algorithm is applied. The optimization is based on the costs of electricity production, encompassing not only the costs of technology, but also the costs of environmental protection and sustainable development. These costs are included in the model and the objectives are formulated accordingly. The objectives are based on maximization of electricity production up to the level of demand, minimization of total electricity costs and minimization of greenhouse gas emissions. In addition, grid losses as well as other limitations and constraints of the electric power system are included into the model. The loss distribution is calculated in proportion to the distance between the supplier and the end user. The solar power plant losses equal zero, because it is assumed that the plant is located in a local community, close to consumers. The results show that the emissions and costs are higher without an introduced solar power plant. Introduction of solar capacities reduces the costs and emissions to a certain level. The developed model may be useful as a decision-support system generator.

The requirements about radon measurements in schools and public buildings included in most of the national and international legislations are generally restricted to all the rooms located at the ground floor and basement, assuming the soil beneath the building as the main source of indoor radon. In order to verify such an assumption for small buildings having at maximum two floors, a preliminary study was performed in 50 schools located in 15 municipalities of the Republic of Srpska. Results of this study suggest that a protocol requiring measurements at the ground floor only may be considered adequate. Due to the high radon spatial variability for rooms at the ground floor, it is preferable to require measurements in a high number of rooms (preferably in all of them) in order to assess the compliance with the reference level established by the legislation.

Today in the age of advanced ceramic civilization, there are a variety of applications for modern ceramics materials with specific properties. Our up-to date research recognizes that ceramics have a fractal configuration nature on the basis of different phenomena. The key property of fractals is their scale-independence. The practical value is that the fractal objects’ interaction and energy is possible at any reasonable scale of magnitude, including the nanoscale and may be even below. This is a consequence of fractal scale independence. This brings us to the conclusion that properties of fractals are valid on any scale (macro, micro, or nano). We also analyzed these questions with experimental results obtained from a comet, here 67P, and also from ceramic grain and pore morphologies on the microstructure level. Fractality, as a scale-independent morphology, provides significant variety of opportunities, for example for energy storage. From the viewpoint of scaling, the relation between large and small in fractal analysis is very important. An ideal fractal can be magnified endlessly but natural morphologies cannot, what is the new light in materials sciences and space.

Installing of new solar capacities for electricity production has slowed down worldwide. To explore this trend, to assess opportunities for implementing solar potential, and to determine whether wider investment in solar capacities is possible, a comprehensive model is developed and applied to 28 EU countries and Serbia. Holistic "triangulation" approach encompasses a correlational multidimensional model, an economic analysis, and societal perspective. First, in a linear regression analysis, number and types of massive input variables were adjusted to maximize the level of explanation of the phenomenon and the significance of the input variables. Calculating 255 combinations of eight types of input data for four years, possible production of solar electricity in the 29 countries was quantified. Calculated results were subjected to complex analyses of sensitivity. Second, the balance between the production cost and market price of solar electricity was analyzed by the economic method of Levelised Cost of Electricity. Third, questionnaires and interviews revealed public opinion and expert opinion. Discussion of current situation and positive practice internationally and in Serbia covers regulatory, financial, and economic aspects, including an assessment of investment risks. In conclusion, interests and opportunities favour wider implementation of solar energy facilities for clean and renewable production of electricity.

The doctoral dissertation provides basic information on solar radiation, photovoltaic conversion of solar radiation, solar cells and solar modules and their output parameters, and a literature review of the current research in the world about dust and solar modules soiling. In addition, the results of the measurement of electrical parameters of clean and solar modules soiled with carbon, calcium carbonate and soil are given. Furthermore, a comparative overview of the results of the energy efficiency tests of the clean and solar modules soiled with carbon, calcium carbonate and soil is given. In the end, the results of the measurement of the electrical parameters of the clean and solar modules soiled with accumulated soot from the chimney of the boiler room, located in the basement of the Faculty of Sciences and Mathematics in Niš, are presented.

The doctoral dissertation presents basic information on the Sun and the solar radiation, photovoltaic conversion of solar radiation, solar cells, temperature and output parameters of the solar modules and PVGIS-CMSAF program. In addition, dissertation presents the results of theoretical and experimental calculation of the amount of electrical energy generated by differently oriented solar modules in Nis and their energy efficiency. Special attention was paid to the results of simultaneous measurements of the climatic parameters, the solar modules temperature and the electrical parameters of differently oriented solar modules for 12 sunny days in the period from 2014 - 2016. At the end of the dissertation examples of practical applications of differently oriented integrated PV systems for electricity generation at a family home and ten-story residential building in Nis and estimation of CO2 emission reduction by using differently oriented integrated PV systems on residential buildings in Nis are given.

The hip joint is one of the largest joints in the body and is a major weight-bearing joint. The function of the hip is to withstand body weight during standing and walking; during single leg stance the hip joint must carry a load three times greater the body weight. However, Joint degeneration is the final phase of the joint cartilage destruction, leading to severe pain, loss of mobility, and sometimes even angular deformity of the limbs. The primary reasons for a large number of total hip replacements are osteoarthritis and osteoporosis of the femoral neck, which often leads to hip fractures. One of the most successful techniques to restore function of a degenerated joint is the total joint replacement. In this surgical procedure, diseased cartilage and parts of the bone are removed and replaced with an appropriate joint prosthesis. Several types of materials and techniques have been developed for this purpose: glass, polymer, metal alloy, ceramics, etc. Earliest prosthesis designs and biomaterials that have been developed to treat osteoarthritic hip degenerated joint surfaces were for the most part empirical and unsuccessful. Joint replacement heralded a revolution after the materials and replacement procedures developed by Sir John Charnley. A modern total hip prosthesis consists of a femoral and acetabular component, where the femoral head is made of cobalt-chrome alloy, alumina or zirconium, and the stem component is now usually made of Ti- or Co-Cr-based alloy. The search for improved designs and new hip implant biomaterials with better biocompatibility and more desirable mechanical properties is still underway.

Upotreba nanotehnologija u cilju razvijanja načina proizvodnje održive energije je jedan od najznačajnijih izazova 21 veka. Izazov je dizajnirati, sintetizovati i izvršiti karakterizaciju novih funkcionalnih nanomaterijala kontrolisanih veličina, oblika i/ili struktura. Nanotehnologija danas privlači punu pažnju ne samo akademske zajednice, već i investitora, vlada i privrede a radi izgradnje i ostvarivanja velikih očekivanja. Ovaj rad istražuje moguću primenu nanotehnologija za nove i unaprijeđene metode pretvaranja energije, uvažavajući potrebe naše sredine. Njihova je jedinstvenost u tome što imaju mogućnost da fabrikuju nove structure na atomskom nivou, kao što su već proizvedeni novi materijali i uređaji sa mogućnošću visoko potencijalne primene u mnogo oblasti. Fokus je na bitnoj ulozi nanomaterijala, pripremi i karakterizaciji nekih nanomaterijala za proizvodnju održive energije, tankoslojnih solarnih ćelija u tehnologiji proizvodnje energije vodonikom., The use of nanotechnology to develop a suite of sustainable energy production schemes is one of the most important scientific challenges of the 21st century. The challenge is to design, to synthesize, and to characterize new functional nanomaterials with controllable sizes, shapes, and/or structures. Nanotechnology is generating a lot of attention these days and therefore building great expectations not only in the academic community but also among investors, the governments, and industry. This paper, explores some of the possible implementations of nanotechnology for new and improved methods of energy conversion, considering a need for this to be done without compromising our environment. Its unique capability to fabricate new structures at atomic scale has already produced novel materials and devices with great potential applications in a wide number of fields. Focus is given to important role of nanomaterials, preparation and characterization some of nanomaterials important for sustainable energy, dye sensitized solar cels and hydrogen production technology.