ABSTRACT
Bio-based composites are increasingly used. One of the most frequently used materials is hemp shives, which is agricultural waste. However, as the quantities of this material are lacking, there is a tendency towards finding new and more available materials. Corncob and sawdust are bio by-products that have great potential as insulation materials. In order to use these aggregates, it is necessary to examine their characteristics. New composite materials based on sawdust, corncobs, styrofoam granules, and the mixture of lime and gypsum as the binder were tested in this research. This paper presents the properties of these composites obtained by determining the porosity of samples, volume mass, water absorption, airflow resistance and heat flux, which was followed by the calculation of the thermal conductivity coefficient. Three of the new biocomposite materials, whose samples were 1-5 cm thick for each type of mixture, were investigated. The aim of this research was to analyze the results of different mixtures and sample thicknesses in order to determine the optimum composite material of the proper thickness so that the best possible thermal and sound insulation could be obtained. Based on the conducted analyses, the biocomposite with a thickness of 5 cm, composed of ground corncobs, styrofoam, lime, and gypsum, proved to be the best in terms of thermal and sound insulation. New composite materials can be used as an alternative to conventional materials.
ABSTRACT
BACKGROUND: The previous review of physical activity (PA) among Croatian children and adolescents was conducted a decade ago. Therefore, the aim of this study was to summarize recent evidence on PA of Croatian children and adolescents and associated personal, social, environmental, and policy factors. METHODS: Eighteen experts reviewed the available evidence and provided ratings (from the lowest grade "F" to the highest grade "A+") for the 10 Global Matrix indicators. A systematic search with 100 keywords was conducted in Hrcak, PubMed/MEDLINE, Scopus, SPORTDiscus, and Web of Science for documents published from January 01, 2012, to April 15, 2022. We also conducted internet searches and secondary analyses of data (relative frequencies) from 6 studies. RESULTS: After assessing 7562 references, we included 90 publications in the review and 18 studies (83.3% of medium-to-good quality) in evidence synthesis. We found a high prevalence of insufficient PA (especially among girls) and excessive screen time (especially among boys). PA participation of children and adolescents in Croatia has declined over time. The following grades were assigned to the indicators for Croatia: B- for overall PA, C- for organized sport and PA, C for active play, C- for active transportation, D+ for sedentary behavior, inconclusive for physical fitness, D+ for family and peers, B- for school, B- for community and environment, and D+ for government. CONCLUSIONS: Coordinated actions are needed across sectors to improve PA promotion, with a focus on increasing PA among girls, reducing sedentary screen time among boys, improving parental support for PA, and further development of national PA policies.
