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The pandemic of the COVID-19 virus disease has resulted in significant changes in everyday life. As a result, two-thirds of the urban population has been forced to alter previously established travel habits. With this in mind, the international scientific community wonders if the newly formed travel habits could be maintained after the pandemic is over. This paper presents the findings of a survey conducted among students in Kragujevac prior to and during the COVID-19 virus pandemic. Furthermore, the citizens' expectations regarding the change in travel habits following the end of the pandemic are presented. For a period of five years, the survey was conducted once a year on students at the Faculty of Engineering in Kragujevac (Serbia). According to the survey results, during the pandemic, the car was considered a more comfortable mode of transportation than before. When compared to before the pandemic, the share of student families with two cars increased by 15%. The number of cyclists has also increased, making the lack of bike paths during the pandemic a more visible issue than previously. The students polled believe that once the pandemic is over, they will walk more and continue to rely on public transportation as before.

In a time of limited water resources, climate change, and significant reductions in fish and plant species, aquaponics systems can play an important role in the future of ecologically and socio-economically sustainable smart cities. The paper aims to investigate the available literature that deals with the topic and current situation related to aquaponics systems - their application, effects of work, perspectives, and shortcomings, as a model of the circular economy. The exploratory method includes a literature review and the analysis of interviews with the pioneers in aquaponics in the Republic of Serbia. The main criterion for reviewing the literature was to find successful examples of aquaponics in the world and the Republic of Serbia. The result of the research is that aquaponics systems, due to the circular way of production, can be included as the model of the circular economy. Among a growing number of aquaponics pioneers, BIGH Farm, ECF Farmsystems, Urban Farmers, Bioaqua Farm, Tilamur, and Water garden currently have a successful implementation of the circular economy. These firms produce food with no waste production, they minimize energy input, and have a positive environmental impact, which are the main aims of the circular economy.

Introduction: Urticaria is a disease of polyetiological origin characterized by skin manifestations (wheals, angioedema or both) and it is frequently seen in childhood. Based on its duration, urticaria can be classified into acute and chronic; and based on causative agents urticaria is divided to spontaneous and inducible. The etiological trigger factors of acute urticaria include infections, medications and food. Aim: Evaluation of etiological factors and clinical parameters of acute urticaria in childhood. Material and methods: We performed a retrospective analysis of medical documentation which included 65 patients with acute urticaria who were treated at the Pediatric Internal Diseases Clinic, Clinical Center Niš, during the period from January 2015 to December 2016. Results: In all subjects, regardless of age, infection was the most frequent factor (42.7%) that preceded the urticaria, while in 13.4% of children infection was associated with the use of medications. In children under 3 years of age, food was the most frequent trigger factor (23.5%), while in older children (above the age of 3) more frequent trigger factor which preceded the acute urticaria was the use of medication during the infection. Among the investigated patients, 63.1% of them had clinical manifestation of urticaria, 20% had angioedema, while 16.9% of patients had urticaria and angioedema at the same time. The evaluation of the laboratory parameters showed high incidence of neutrophilia (40.6%) and increased CRP values (32.5%). Conclusion: The most common trigger factors which caused acute urticaria in childhood were the upper respiratory tract infections. A high incidence of medications was detected in the group of children older than three years, while in children younger than 3 years, food was detected as the most frequent potential cause. Neutrophilia and increased CRP values were laboratory parameters associated with infections.

In the past decades, the automotive industry is growing proportionally with the rapid population increase. On the other hand, increasing energy consumption and the use of fossil fuels have led to increased environmental pollution. A new trend in the automotive industry in the last twenty years is the development of new types of vehicles that are powered by renewable energy and the solar-powered vehicle is very popular among them. Solar photovoltaic technologies are very convenient for electric and hybrid vehicles, due to the direct conversion of solar energy to electricity, the low cost of photovoltaic panels, and their positive environmental impact. There are various types of solar cars developed by different companies, which have remarkable development in terms of materials, energy management systems, and used mechanical and electrical components. This paper represents an overview of solar energy applications in the automotive industry and the development of solar and hybrid cars. Also, a comparative analysis of different solar vehicles is presented, with the possibilities for further investigation and development of solar energy applications in the automotive industry.