Residence time of singlet oxygen in membranes

Photodynamic therapy uses photosensitizers (PS) to kill cancer cells by generating reactive oxygen species like singlet oxygen (SO) - upon illumination with visible light. PS membrane anchoring augments local SO concentration, which in turn increases photodynamic efficiency. The latter may suffer from SOs escape into the aqueous solution or premature quenching. Here we determined the time constants of SO escape and quenching by target molecules to be in the nanosecond range, the former being threefold longer. We confined PS and dipolar target molecules either to different membrane monolayers or to the same leaflet and assessed their abundance by fluorescence correlation spectroscopy or membrane surface potential measurements. The rate at which the contribution of the dipolar target molecules to membrane dipole potential vanished, served as a measure of the photo-oxidation rate. The solution of the reactiondiffusion equations did not indicate diffusional rate limitations. Nevertheless, reducing the PS-target distance increased photodynamic efficiency by preventing other SO susceptible moieties from protecting the target. Importantly, our analytical model revealed a fourfold difference between SO generation rates per molecule of the two used PSs. Such analysis of PS quantum yield in a membrane environment may help in designing better PSs.14-13-01373P(VLID)341513

Anthropogenic soils and landscapes of European Russia: Summer school from sea to sea—A didactic prototype

Field excursions and trainings are considered a key component of education programs in soil and environmental sciences. They allow mastering students’ practical skills in sampling and onsite assessments and improve understanding of ecosystem integrity and complexity. Urbanization has a substantial impact on soil properties and functions; however, field courses focused on urban soils are rare. We present a didactic prototype and the outcomes of the “Monitoring, Modeling, and Management of Urban Green Infrastructure and Soils (3MUGIS)” summer school—the first educational tour observing anthropogenic soils and landscapes along the bioclimatic gradient in European Russia, from tundra to dry steppes. Didactic learning was based on a studying-by-doing approach; students were involved in environmental assessment in multiple regions varying in climatic and socioeconomic features. Considering the high spatial heterogeneity of urban ecosystems, we used express techniques (portable X-ray fluorescence, infrared gas analyzers) for onsite soil analysis at multiple replicas. The data collected were discussed with local and international experts from Russia, Germany, the United States, and France in the context of regional environmental problems (e.g., pollution, soil degradation, and urban expansion). Students discovered zonal changes in vegetation (e.g., increasing tree height and diversity from north taiga to forest steppes) and soil properties (e.g., a gradual increase in pH and changes in soil organic C), as well as urban-specific processes and features (e.g., urban heat island effect or soil artifacts). The overall student feedback was very positive (50.8% excellent, 36% good); some specific organizational issues will be addressed for future 3MUGIS summer schools. © 2020 The Authors. Journal of Environmental Quality © 2020 American Society of Agronomy, Crop Science Society of America, and Soil Science Society of Americ

Молодежь в политической и социокультурной жизни Африки

Представляемая работа является первым за последние 25 лет монографическим изданием, посвященным проблемам африканской молодежи и ее роли в становлении и развитии молодых государств. Особое внимание уделяется вопросам социализации и формирования идентичности как в традиционном, так и в современном обществах, спецификt молодежных политических движений и молодежной политике государственных структур. Затрагиваются вопросы демографического фактора и влияния средств массовой информации на решении проблемы занятости