Background Because of the COVID-19 pandemic, people were recommended to implement new health behaviors into their daily routines to prevent the viral spread. The aim of this study was to investigate whether specific health behaviors, such as wearing face masks, taking immunity boosters and visiting risky places were associated with a higher level of stress due to COVID-19 in the general adult population. Method This cross-sectional study was conducted from September 1, 2020 to October 1, 2021 in eight randomly chosen cities of two Serbian speaking countries (Republic of Serbia and Republic of Srpska - Bosnia and Herzegovina). Participants filled a socio-epidemiologic questionnaire, COVID Stress Scales (CSS) and the Perceived Stress Scale (PSS). Results The study included 2,301 participants with an average age of 36.72 ± 13.82 years of whom 54.9% were female (p = 0.001). Most participants were healthy, highly educated, employed, married, non-smokers and consumed alcohol. The mean total CSS score was 32.7 ± 23.8 out of 144, suggesting a relatively low stress due to COVID-19. The mean PSS was 19.43 ± 5.05 out of 40 indicating slightly increased level of general stress. Participants who reported higher CSS scores were more likely to wear face masks, use immunity boosters, go to cafes and clubs, have chronic illnesses, have suspicious, but not proven contact with COVID-19 positive people, and use multiple sources of information about COVID-19. Conclusion Few participants experienced high levels of stress due to COVID-19. People who used face masks, immunity boosters and visited risky places reported a higher level of stress during the pandemic. Supplementary Information The online version contains supplementary material available at 10.1186/s41043-025-00833-2.

Fly ash (FA) is a low-cost industrial waste material mostly composed of oxides. These small, hard particles can be used as reinforcements in composite production. In this study, an A356.0 aluminum alloy reinforced with 4 wt.% FA was synthesized by compo casting and subsequently subjected to multiple passes of equal channel angular extrusion (ECAE) to investigate the influence of intense plastic deformation on the composite hardness and microstructure. Microstructure analysis was performed on an optical microscope and by computer tomography (CT). The as-cast alloy contains a relatively homogeneous microstructure with minor FA agglomerations and very low porosity. The severe plastic deformation induced by ECAE results in a directed structure and additional integration of FA into the matrix with the disappearance of pores. Vickers hardness measurement of aluminum/fly ash (Al/FA) composite was carried out with different indentation loads: 0.196 N (HV0.02), 0.490 N (HV0.05), 0.981 N (HV0.1), and 1.960 N (HV0.2). The results showed that hardness increases after each ECAE pass because of microstructure changes. Already after the first pass, a significant increase in hardness is achieved, ranging from 27% (HV0.05) to 62% (HV0.2). A Meyer’s index (n) value greater than 2 indicates that the hardness of single and double extruded composite depends on the indentation load. Extruded samples show a hardness enhancement with increasing applied load, so the examined composite exhibits a reverse indentation size effect (RISE).