The lockdown of schools in Spain to confront the effects of COVID-19 caused an enormous impact at both societal and educational levels. Schools and families had to react rapidly to a new teaching and learning scenario without the benefit of previous planning or government guidelines. In this context, some schools were better able to adapt to the new circumstances than others. Likewise, the structure and size of families' economic, social and cultural capital produced significant differences in the learning opportunities for children from different backgrounds. This article assesses the impact of the school lockdown on the learning gap between children from different social backgrounds in Catalonia. Based on 35,419 responses to an online survey administered between 26 and 30 March 2020 to families with children aged between 3 and 18, the authors' analysis shows that learning opportunities varied significantly. Middle-class families were able to maintain higher standards of education quality in a critical context, while children from socially disadvantaged families had few learning opportunities both in terms of time and learning experiences (schoolwork and maintenance of after-school activities). Results differed by type of school (public/ private) where students were enrolled, family economic, social and cultural capital, and family living conditions. In the final part of the article, the authors highlight the importance of the role of the school in ensuring learning opportunities for children from low socioeconomic backgrounds, and they discuss some policy implications of their findings.

Reducing physical contact has been the most common strategy adopted by governments to reduce the spread of the COVID-19 disease. It has led most countries to close their schools. Previous evidence on the effects of teacher strikes, summer holidays, armed conflicts or any other cause of school closure on learning suggest that the effects of COVID-19 will be highly significant for some and will vary depending on students' previous performance, family characteristics, age or education track, among other factors.Recent evidence shows that learning losses during school closures have been widespread and especially intense among the more disadvantaged students. In this article we evaluate the magnitude of the gap regarding opportunities to learn in formal, informal and non-formal education between families depending on their cultural and economic capital. An online survey (n = 35,937) was carried out during the second week of the confinement (March 2020) in Catalonia. The survey targeted families with children between three and eighteen years. The responses show remarkable social inequalities in opportunities to learn. In this article, we describe the magnitude of the learning gap between social groups and explore which are the most significant factors that explain educational inequalities. Our

We have investigated the structure of single-stranded (ss) DNA self-assembled monolayers (SAMs) on gold by combining peak force tapping, Kelvin probe and phase contrast atomic force microscopy (AFM) techniques. The adhesion, surface potential and phase shift signals show heterogeneities in the DNA film structure at two levels: microscale and nanoscale; which cannot be clearly discerned in the topography. Firstly, there is multilayer aggregation covering less than 5% of the surface. The DNA multilayers seem to be ordered phases and their existence suggests that DNA end-to-end interaction can play a role in the self-assembly process. Secondly, we find the formation of two phases in the DNA monolayer, which differ both in surface energy and surface potential. We relate the two domains to differences in the packing density and in the ssDNA conformation. The discovered heterogeneities in ssDNA SAMs provide a new scenario in our vision of these relevant films that have direct consequences on their biological, chemical and physical properties.

Genetic interventions on microbiomes, for clinical or biotechnological purposes, remain challenging. Conjugation-based delivery of genetic cargo is still unspecific and limited by low conjugation rates. Here we report an approach to overcome these problems, based on a synthetic bacterial adhesion system. Mating assemblers consist on a synthetic adhesion formed by the expression on the surface of donor and target cells of specific nanobodies (Nb) and their cognate antigen (Ag). The Nb–Ag bridge increased 1–3 logs transfer of a variety of plasmids, especially in liquid media, confirming that cell-cell docking is a main determinant limiting mating efficiency. Synthetic cell-to-cell adhesion allows efficient conjugation to targeted recipients, enhancing delivery of desired genes to a predefined subset of prey species, or even specific pathogenic strains such as enterohemorrhagic Escherichia coli (EHEC), within a bacterial community. The synthetic conjugation enhancer presented here optimizes plasmid delivery by selecting the target hosts with high selectivity.