Oxidative Potential of Atmospheric Particles at an Eastern Mediterranean Site

Aerosol oxidative potential (OP; the inherent ability of ambient particles to generate reactive oxygen species in vivo) may be linked to the health effects of population exposure to aerosol and is a metric of their toxicity. The goal of this work was to quantify the water-soluble OP of particles in an urban area in Patras, Greece and to investigate its links with source emissions or components of this particulate matter (PM). A field campaign was conducted during a monthlong wintertime period in 2020 (January 10 to February 13) on the campus of the University of Peloponnese in the southwest of Patras. During this time, ambient filter samples (a total of 35 filters) were collected. To measure the water-soluble OP we used a semiautomated system similar to Fang et al. (2015) based on the dithiothreitol (DTT) assay. The accuracy of our system was validated by measuring the DTT activity of 11 phenanthrequinone (PQN) solutions on both our system and the identical semi-automated validated system at the National Observatory of Athens (NOA). These two sets of analysed DTT activities (current vs. NOA system) were significantly correlated (R2=0.99) with a slope of 1.15 ± 0.04 and an intercept close to zero. We found that the average water-soluble OP in Patras was 1.5 ± 0.3 nmol min-1 m-3, ranging from 0.7 to 2 nmol min-1 m-3. The OP measured in Patras during the campaign is higher than reported values from similar wintertime studies in other urban areas such as Athens (Paraskevopoulou et al., 2019). The average watersoluble OP during a summer study for Patras was significantly lower and equal to 0.18 ± 0.02 nmol min-1 m- 3. Taking into account the average PM1 mass concentrations for these two periods (summer: 6 μg m-3 and winter: 23 μg m-3) it is clear that the increase in OP was two times the increase in PM mass making the wintertime aerosol more toxic. Additionally, the water-soluble brown carbon (BrC) was determined using an offline semi-automated system, where absorption was measured over a 1 m path length. The average BrC absorption in Patras at a wavelength of 365 nm was 8.6 ± 3.9 Mm-1 suggesting that there was significant BrC in the organic aerosol during this period. The coefficients of determination, R2, in Table 1 are used as a metric of the potential relationships between the various carbonaceous aerosol components and the DTT activity. The results suggest that the OP is not dominated by a single source or component, but that there are multiple components contributing to it during the study period. Interestingly, the highest correlation coefficient (R2 = 0.46) was found between the OP and Brown Carbon. This is consistent with recently published results for an urban site in Atlanta where the oxidative potential measured with the DTT method also had stronger correlations with BrC during the winter (Gao et al., 2020)

Sources of water-soluble Brown Carbon at a South-Eastern European Site

Atmospheric brown carbon (BrC) is a highly uncertain, but potentially important contributor to light absorption in the atmosphere. Laboratory and field studies have shown that BrC can be produced from multiple sources, including primary emissions from fossil fuel combustion and biomass burning (BB), as well as secondary formation through a number of reaction pathways. It is currently thought that the dominant source of atmospheric BrC is primary emissions from BB, but relatively few studies demonstrate this in environments with complex source profiles. A field campaign was conducted during a month-long wintertime period in 2020 on the campus of the University of Peloponnese in the southwest of Patras, Greece which represents an urban site. During this time, ambient filter samples (a total of 35 filters) were collected from which the water-soluble BrC was determined using a semi-automated system similar to Hecobian et al. (2010), where absorption was measured over a 1 m path length. To measure the BrC, a UV-Vis Spectrophotometer was coupled to a Liquid Waveguide Capillary Cell and the light absorption intensity was recorded at 365 and 700 nm. The latter was used as a reference wavelength. We found that the average BrC absorption in Patras at a wavelength of 365 nm was 8.5 ± 3.9 Mm-1 suggesting that there was significant BrC in the organic aerosol during this period. Attribution of sources of BrC was done using simultaneous chemical composition data observations (primarily organic carbon, black carbon, and nitrate) combined with Positive Matrix Factorization analysis. This analysis showed that in addition to the important role of biomass burning (a contribution of about 20%) and other combustion emissions (also close to 20%), oxidized organic aerosol (approximately 40%) is also a significant contributor to BrC in the study area. Reference Hecobian, A., Zhang, X., Zheng, M., Frank, N., Edgerton, E.S., Weber, R.J., 2010. Water-soluble organic aerosol material and the light-absorption characteristics of aqueous extracts measured over the Southeastern United States. Atmos. Chem. Phys. 10, 5965–5977. https://doi.org/10.5194/acp-10-5965-201

Inhibition of Fungi and Gram-Negative Bacteria by Bacteriocin BacTN635 Produced by Lactobacillus plantarum sp. TN635

The aim of this study was to evaluate 54 lactic acid bacteria (LAB) strains isolated from meat, fermented vegetables and dairy products for their capacity to produce antimicrobial activities against several bacteria and fungi. The strain designed TN635 has been selected for advanced studies. The supernatant culture of this strain inhibits the growth of all tested pathogenic including the four Gram-negative bacteria (Salmonella enterica ATCC43972, Pseudomonas aeruginosa ATCC 49189, Hafnia sp. and Serratia sp.) and the pathogenic fungus Candida tropicalis R2 CIP203. Based on the nucleotide sequence of the 16S rRNA gene of the strain TN635 (1,540 pb accession no FN252881) and the phylogenetic analysis, we propose the assignment of our new isolate bacterium as Lactobacillus plantarum sp. TN635 strain. Its antimicrobial compound was determined as a proteinaceous substance, stable to heat and to treatment with surfactants and organic solvents. Highest antimicrobial activity was found between pH 3 and 11 with an optimum at pH = 7. The BacTN635 was purified to homogeneity by a four-step protocol involving ammonium sulfate precipitation, centrifugal microconcentrators with a 10-kDa membrane cutoff, gel filtration Sephadex G-25, and C18 reverse-phase HPLC. SDS-PAGE analysis of the purified BacTN635, revealed a single band with an estimated molecular mass of approximately 4 kDa. The maximum bacteriocin production (5,000 AU/ml) was recorded after a 16-h incubation in Man, Rogosa, and Sharpe (MRS) medium at 30 °C. The mode of action of the partial purified BacTN635 was identified as bactericidal against Listeria ivanovii BUG 496 and as fungistatic against C. tropicalis R2 CIP203

Significant spatial gradients in new particle formation frequency in Greece during summer

Extensive continuous particle number size distribution measurements took place during two summers (2020 and 2021) at 11 sites in Greece for the investigation of the frequency and the spatial extent of new particle formation (NPF). The study area is characterized by high solar intensity and fast photochemistry and has moderate to low fine particulate matter levels during the summer. The average PM2.5 levels were relatively uniform across the examined sites. The NPF frequency during summer varied from close to zero in the southwestern parts of Greece to more than 60 % in the northern, central, and eastern regions. The mean particle growth rate for each station varied between 3.4 and 8 nm h−1, with an average rate of 5.7 nm h−1. At most of the sites there was no statistical difference in the condensation sink between NPF event and non-event days, while lower relative humidity was observed during the events. The high-NPF-frequency sites in the north and northeast were in close proximity to both coal-fired power plants (high emissions of SO2) and agricultural areas with some of the highest ammonia emissions in the country. The southern and western parts of Greece, where NPF was infrequent, were characterized by low ammonia emissions, while moderate levels of sulfuric acid were estimated (107 molec. cm−3) in the west. Although the emissions of biogenic volatile organic compounds were higher in western and southern sectors, they did not appear to lead to enhanced frequency of NPF. The infrequent events at these sites occurred when the air masses had spent a few hours over areas with agricultural activities and thus elevated ammonia emissions. Air masses arriving at the sites directly from the sea were not connected with atmospheric NPF. These results support the hypothesis that ammonia and/or amines limit new particle formation in the study area.</p

Research on the housing conditions of the Roma minority in Greece. Application in the municipality of Megara

185 σ.Η Επιτροπή για τη Νομική Ενίχυση των Πτωχών (Commission on Legal Empowerment of the Poor), που συστάθηκε το 2005 από μία ομάδα αναπτυγμένων και αναπτυσσόμενων κρατών, τονίζει στο κείμενό της “Making the law work for everyone” (2008) ότι υπάρχει άμεση ανάγκη για ένταξη των κοινωνικά και οικονομικά αποκλεισμένων πληθυσμιακών ομάδων. Ένας από τους βασικούς άξονες του κειμένου αυτού της Επιτροπής είναι τα ιδιοκτησιακά δικαιώματα και η πρόσβαση σε γη και στέγαση των παραπάνω ομάδων, τομέας άρρηκτα συνδεδεμένος με τα συστήματα διαχείρισης και τις πολιτικές γης. Οι μειονότητες, εν γένει, και η μειονότητα των Ρομά, εν είδει, που διαβιούν στον ευρωπαϊκό χώρο εμπίπτουν κατά κοινή ομολογία στις αποκλεισμένες ομάδες στις οποίες αναφέρεται το παραπάνω κείμενο. Συγκεκριμένα, οι Ρομά, ομάδα με μακρόχρονη παρουσία στον ευρωπαϊκό χώρο, είναι, σύμφωνα με το European Roma Rights Centre, η μεγαλύτερη πληθυσμιακή μειονότητα στην Ευρώπη, παρά το γεγονός ότι δεν υπάρχει ακριβής εκτίμηση του συνολικού πληθυσμού της. Η πρόσβαση των Ρομά σε βασικά δικαιώματα γης και ιδιοκτησίας, καθώς και η οικιστική τους κατάσταση στους καταυλισμούς που αυτοί διαβιούν, μπορούν να θεωρηθούν γενικά προβληματικές και χαρακτηρίζονται από αβεβαιότητα σχετικά με το ιδιοκτησιακό καθεστώς του χώρου στον οποίο βρίσκονται, έλλειψη τίτλου ιδιοκτησίας που συχνά οδηγεί σε εκδιώξεις από την πολιτεία, ελλειπή πρόσβαση σε στοιχειώδεις υποδομές και γενικότερα, φαινόμενα περιθωριοποίησης από τις υπόλοιπες κοινωνικές ομάδες. Στόχος της συγκεκριμένης διπλωματικής εργασίας είναι η διερεύνηση της υπάρχουσας οικιστικής κατάστασης της μειονότητας των Ρομά στον ελλαδικό χώρο, αναδεικνύοντας τα προβλήματα σχετικά με την πρόσβασή τους σε γη και ιδιοκτησία και το υπάρχον νομικό πλαίσιο για τη γενικότερη κοινωνική τους ένταξη. Τέλος, επιχειρείται μία περαιτέρω εμβάθυνση στην οικιστική κατάσταση της εν λόγω μειονότητας σε συγκεκριμένο χώρο διαμονής τους στην περιοχή Βλυχού του Δήμου Μεγαρέων.In its final report, “making the law work for everyone” (2008), the Commission on Legal Empowerment of the Poor (est. 2005), being the initiative of a group of industrialised and developing countries, states the outmost importance of the social and economical inclusion of the poor and dispossessed. One of the four main pillars for legal empowerment, mentioned in the Commission’s report, is property rights and the access to land and housing of the aforementioned social groups. These areas are closely related to land management systems and land policies. Minorities, including the Roma minority in Europe, are one of the socially and economically excluded groups that the Commission mentions in its report. The European Roma minority (being one of the oldest minorities in the continent), is according to the European Roma Rights Centre, the biggest one in this particular region, despite the fact that an actual accurate number for its population does not, as of yet, exist. The access of the Roma minority to basic land and property rights, as well as the housing conditions in their settlements, can in general be thought of as lacking, and are characterised by uncertainty over the ownership of the land on which settlements are placed, lack of security of tenure that often leads to forced evictions, inadequate access to public services, and in a general segregation from other communities. The purpose of this particular paper is to report on the existing housing conditions of the Roma minority in the region of Greece and the problems that arise relating to their access to land and housing, as well as the existing legal framework for their general social inclusion. Finally, an in-depth analysis is attempted, relating to the housing conditions of the Roma settlement “Vlychos”, in the municipality of Megara.Ιωάννης Δ. Ακτύπη

Use of Artificial Neural Networks and a Gamma-Concept-Based Approach To Model Growth of and Bacteriocin Production by Streptococcus macedonicus ACA-DC 198 under Simulated Conditions of Kasseri Cheese Production

Growth of and bacteriocin production by Streptococcus macedonicus ACA-DC 198 were assessed and modeled under conditions simulating Kasseri cheese production. Controlled fermentations were performed in milk supplemented with yeast extract at different combinations of temperature (25, 40, and 55°C), constant pH (pHs 5 and 6), and added NaCl (at concentrations of 0, 2, and 4%, wt/vol). The data obtained were used to construct two types of predictive models, namely, a modeling approach based on the gamma concept, as well as a model based on artificial neural networks (ANNs). The latter computational methods were used on 36 control fermentations to quantify the complex relationships between the conditions applied (temperature, pH, and NaCl) and population behavior and to calculate the associated biokinetic parameters, i.e., maximum specific growth and cell count decrease rates and specific bacteriocin production. The functions obtained were able to estimate these biokinetic parameters for four validation fermentation experiments and obtained good agreement between modeled and experimental values. Overall, these experiments show that both methods can be successfully used to unravel complex kinetic patterns within biological data of this kind and to predict population kinetics. Whereas ANNs yield a better correlation between experimental and predicted results, the gamma-concept-based model is more suitable for biological interpretation. Also, while the gamma-concept-based model has not been designed for modeling of other biokinetic parameters than the specific growth rate, ANNs are able to deal with any parameter of relevance, including specific bacteriocin production