Twenty-one propolis samples produced by 12 different Meliponinae species were analyzed by GC-MS. Several chemical types of stingless bees’ propolis could be grouped, according to the prevailing type of compounds like: “gallic acid”, “diterpenic” and “triterpenic” types. The results confirm that neither the bee species nor the geographical location determine the chemical composition of Meliponinae propolis and the choice of its plant source, respectively. This could be explained by the fact that Meliponinae forage over short distances (maximum 500 m) and thus use as propolis source the first plant exudate they encounter during their flights. The antibacterial, antifungal and cytotoxic activities of the samples were also investigated. Most samples had weak or no activity against E. coli, weak action against Candida albicans. Some of them showed significant activity against St. aureus., presumably connected to the high concentration of diterpenic acids. Samples rich in diterpenic acids possessed also high cytotoxic activity (Artemia salina test).

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The chemical composition of propolis from Bulgaria, Turkey, Greece and Algeria was investigated by GC-MS. All of them contained mainly flavonoids and esters of caffeic and ferulic acids, which indicated that their main source are buds of poplars of the taxonomic section Aegieros. Some Turkish samples contained a low percent of diterpenic acids, while in Algerian samples significant amounts of a hydroxyditerpenic acid (M=322, its structure not determined by its MS) were found. All samples showed significant antibacterial and weak to moderate antifungal activity.

The effects of seven (prenyl-and methoxy-) derivatives of cinnamic acid (0.1 mM) on the kinetics of lipid (sunflower oil triacylglycerols, TGSO) bulk phase oxidation at 80°C have been compared. Synthesis of prenyl cinnamic acid derivatives: 3-prenyl-4-hydroxy-cinnamic acid (PHC), 3,5-diprenyl-4-hydroxy-cinnamic acid (DPHC), 2,2-dimethyl-6-carboxy-ethenyl-2H-benzopyran (DMCB), 2,2-dimethyl-6-carboxy-ethenyl-8-prenyl-2H-benzopyran (DCEPB) present in Brazilian propolis has been performed. The monoprenyl derivative (PHC) has been found to exert a higher antioxidant activity as compared to the diprenyl derivative (DPHC). However, cinnamic acid derivatives DMCB and DCEPB have caused no change in the kinetics of TGSO oxidation. The results obtained have been compared with those on related compounds containing a cinnamic acid moiety as a structural feature, such as 4-hydroxy-cinnamic (p-coumaric), 3-methoxy-4-hydroxy-cinnamic (ferulic) and 3,5-dimethoxy-4-hydroxy-cinnamic (sinapic) acids, as well as with data on butylated hydroxytoluene (BHT) and α-tocopherol (α-Toc). PHC has shown a stronger antioxidant efficiency than BHT, p-coumaric and ferulic acid, but a weaker antioxidant efficiency than α-Toc and sinapic acid. The observed antioxidant effect of DPHC was stronger than that of p-coumaric and ferulic acids and weaker than that of α-Toc, BHT and sinapic acid.

The effects of seven (prenyl-and methoxy-) derivatives of cinnamic acid (0.1 mM) on the kinetics of lipid (sunflower oil triacylglycerols, TGSO) bulk phase oxidation at 80°C have been compared. Synthesis of prenyl cinnamic acid derivatives: 3-prenyl-4hydroxy-cinnamic acid (PHC), 3,5-diprenyl-4-hydroxy-cinnamic acid (DPHC), 2,2-dimethyl-6-carboxy-ethenyl-2H-benzopyran (DMCB), 2,2-dimethyl-6-carboxy-ethenyl-8prenyl-2H-benzopyran (DCEPB) present in Brazilian propolis has been performed. The monoprenyl derivative (PHC) has been found to exert a higher antioxidant activity as compared to the diprenyl derivative (DPHC). However, cinnamic acid derivatives DMCB and DCEPB have caused no change in the kinetics of TGSO oxidation. The results obtained have been compared with those on related compounds containing a cinnamic acid moiety as a structural feature, such as 4-hydroxy-cinnamic (p-coumaric), 3-methoxy-4-hydroxy-cinnamic (ferulic) and 3,5-dimethoxy-4-hydroxy-cinnamic (sinapic) acids, as well as with data on butylated hydroxytoluene (BHT) and α-tocopherol (α-Toc). PHC has shown a stronger antioxidant efficiency than BHT, p-coumaric and ferulic acid, but a weaker antioxidant efficiency than α-Toc and sinapic acid. The observed antioxidant effect of DPHC was stronger than that of p-coumaric and ferulic acids and weaker than that of α-Toc, BHT and sinapic acid.

The report analyzes the results of an empirical study conducted in 2019 with 562 teachers from different types of schools, settlements in Bulgaria and stages of education. Their views and attitude to the application of innovative methods in school activities – curricular, extracurricular and others were monitored. Based on the collected data, a profile of the modern teacher as a school innovator was outlined. The report include information about: what forms, methods and tools teachers use in their practice; what innovative methods they know, how often apply them and what motivated them; whether the innovative methods help in the student’s learning process; the extent to which innovative teaching methods increase the quality of learning content. A special focus in the study was placed on the role of teacher’s education and proffesional qualification for the application of innovative methods, as well as school management for the introduction of innovations and support to teachers in this process.

Failure is an intrinsic part of systems, including construction. While there is a less than consistent understanding of what failure is, it is an aspect of human nature that we wish to learn from mistakes. To gain insights into how failure is understood and what failure means in construction, and as a precursor to developing learning materials for higher education students, the outcomes of 19 semi-structured interviews with construction personnel in the UK are presented. The interviews explore processes employed by the construction industry to capture, understand and extract learning from these events, including an exploration of any perceived attitudes towards failure, and whether such attitudes are barriers or aids to effective learning in practice. Findings revealed different types of failure within the construction industry, manifested as separate and individually developed learning cycles, while attitudes towards failure impact the learning process. Two pairs of attitude stimuli were revealed: Ownership and Blame; Acceptance and Leadership. These findings are then used to provide learning tools for undergraduate students in built environment degree programmes. A taxonomy of failure was developed, incorporating three levels of causes, symptoms and consequences. A face validity exercise with industry experts provides the confidence to adopt this taxonomic approach.