Probing Greek secondary school students’ awareness of green chemistry principles infused in context-based projects related to socio-scientific issues

This study aims at investigating students’ awareness of green chemistry principles (GCPs) which are infused in two context-based projects that are related to socio-scientific issues, namely climate change and materials’ recycling. At first, content analysis of the projects’ activities showed the infusion of four GCPs. Subsequently, the students’ written reports associated with these activities were evaluated in order to examine the incorporation of different GCPs in their argumentation. The four principles identified in the first part of the study, were also shown to be incorporated in students’ argumentation, although with variable frequency. The specific themes which manifest students’ awareness of the different GCPs were also identified. These themes may guide the effective design of educational material dedicated to the infusion of GCPs in chemistry education, thus contributing to the promotion of students’ environmental awareness and the development of skills which characterise socially responsible citizenship. © 2021 Informa UK Limited, trading as Taylor & Francis Group

Near-IR irradiation of the S-2 state of the water oxidizing complex of photosystem II at liquid helium temperatures produces the metalloradical intermediate attributed to S1YZ center dot

Near-IR (NIR) excitation at liquid He temperatures of photosystem II (PSII) membranes from the cyanobacterium Synechococcus vulcanus or from spinach poised in the S-2 state results in the production of a g = 2.035 EPR resonance, reminiscent of metalloradical signals. The signal is smaller in the spinach preparations, but it is significantly enhanced by the addition of exogenous quinones. Ethanol (2-3%, v/v) eliminates the ability to trap the signal. The g = 2.035 signal is identical to the one recently obtained by Nugent et a]. by visible-light illumination of the S, state, and preferably assigned to S1Yz. [Nugent, J. H. A., Muhiuddin, I. P., and Evans, M. C. W. (2002) Biochemistry 41, 4117-4126]. The production of the g = 2.035 signal by liquid He temperature NIR excitation of the S, state is paralleled by a significant reduction (typically 40-45% in S. vulcanus) of the S-2 state multiline signal. This is in part due to the conversion of the Mn cluster to higher spin states, an effect documented by Boussac et al. [Boussac, A., Un, S., Horner, O., and Rutherford, A. W. (1998) Biochemistry 37, 4001-4007], and in part due to the conversion to the g = 2.035 configuration. Following the decay of the g = 2.035 signal at liquid helium temperatures (decay halftimes in the time range of a few to tens of minutes depending on the preparation), annealing at elevated temperatures (-80 degreesC) results in only partial restoration of the S-2 state multiline signal. The full size of the signal can be restored by visible-light illumination at -80 degreesC, implying that during the near-IR excitation and subsequent storage at liquid helium temperatures recombination with Q(A)(-) (and therefore decay of the S-2 state to the S, state) occurred in a fraction of centers. In support of this conclusion, the g = 2.035 signal remains stable for several hours (at 11 K) in centers poised in the S(2)(...)Q(A) configuration before the NIR excitation. The extended stability of the signal under these conditions has allowed the measurement of the microwave power saturation and the temperature dependence in the temperature range of 3.8-11 K. The signal intensity follows Curie law temperature dependence, which suggests that it arises from a ground spin state, or a very low-lying excited spin state. The P-1/2 (microwave power at half-saturation) value is 1.7 mW at 3.8 K and increases to 96 mW at 11 K. The large width of the g = 2.035 signal and its relatively fast relaxation support the assignment to a radical species in the proximity of the Mn cluster. The whole phenomenology of the g = 2.035 signal production is analogous to the effects of NIR excitation on the S-3 state [loannidis, N., Nugent, J. H. A., and Petrouleas, V. (2002) Biochemistry 41, 9589-9600] producing an S-2'y(Z)(.) intermediate. In the present case, the intermediate is assigned to S1YZ*. The NIR-induced increase in the oxidative capability of the Mn cluster is discussed in relation to the photochemical properties of a Mn(III) ion that exists in both S-2 and S-3 states. The EPR properties of the S1YZ* intermediate cannot be reconciled easily with our current understanding of the magnetic properties of the S, state. It is suggested that oxidation of tyr Z alters the magnetic properties of the Mn cluster via exchange of a proton

Preliminary background indoor EMF measurements in Greece

The main purpose of this work was to investigate the fluctuation of Greek indoor electromagnetic field (EMF) intensity values and identify peaks that might occur. The scientific interest is mainly focused on the bands of extremely low-frequency (ELF) magnetic fields and radiofrequency (RF) electric fields which have been suggested to be possibly carcinogenic to humans by the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR).Electromagnetic radiation (EMR) measurements were performed in a variety of indoor dwellings, in Attica and in the islands of Zakynthos and Lesvos.A total number of 4540 measurements were taken in a wide frequency range (50 Hz-2100 MHz) of which 3301 in Attica, 963 in Lesvos and 276 in Zakynthos.Statistical analysis of the data revealed specific statistically significant differences between the mean values of the electric (ELF and RF) but not the magnetic (ELF) field strengths measured at different distances from the EMF source, as well as between some of the mean values of the RF electric field at different bands. Some statistically significant differences between mean electric field values at different geographic locations were also identified.As far as the RF electric field is concerned, the maximum values, in most cases, were below 0.5 V/m, however increased values above 1 V/m and up to 5.6 V/m were occasionally observed. The ELF magnetic field values were lower than 1 μT. It may be concluded that overall, the observed indoor EMF intensity values remained well below domestic and European established limits. © 2015 Associazione Italiana di Fisica Medica

A study on the clustering of extra virgin olive oils extracted from cultivars growing in four ionian islands (Greece) by multivariate analysis of their phenolic profile, antioxidant activity and genetic markers

Background: The phenolic fraction of extra virgin olive oil (EVOO) has disease preventive and health-promoting properties which are supported by numerous studies. As such, EVOO is defined as a functional food. The aim of the present study was to characterize the phenolic profile of olive oil from cultivars farmed in the Ionian Islands (Zakynthos, Kefalonia, Lefkada, and Kerkyra) and to investigate the association of phenols to antioxidant activity, which is central to its functionality. Furthermore, the study investigates whether multivariate analyses on the concentration of individual biophenolic compounds and genetic population diversity could classify the olive oil samples based on their geographic origin. Methods: Phenols were determined in 103 samples from different Ionian Island tree populations by1H nuclear magnetic resonance (NMR), and sample antioxidant activity was measured by their capacity to reduce the free radical 2,2-diphenyl-1-picrylhydrazyl) (DPPH). Genetic diversity was measured by estimating Nei’s population genetic distance using 15 reproducible bands from random amplified polymorphic DNA (RAPD) genotyping. Results: Principal component analysis (PCA) of the secoiridoid concentrations clustered samples according to cultivar. Clustering based on genetic distances is not concordant with phenolic clustering. A cultivar effect was also demonstrated in the association between the concentration of individual phenols with DPPH reducing activity. Conclusions: Taken together, the study shows that the olive oil phenolic content defines “cultivar-specific phenolic profiles” and that environmental factors other than agronomic conditions contribute more to phenotype variance than genetics. © 2021 by the authors. Licensee MDPI, Basel, Switzerland