Resource limitation drives spatial organization in microbial groups.

Dense microbial groups such as bacterial biofilms commonly contain a diversity of cell types that define their functioning. However, we have a limited understanding of what maintains, or purges, this diversity. Theory suggests that resource levels are key to understanding diversity and the spatial arrangement of genotypes in microbial groups, but we need empirical tests. Here we use theory and experiments to study the effects of nutrient level on spatio-genetic structuring and diversity in bacterial colonies. Well-fed colonies maintain larger well-mixed areas, but they also expand more rapidly compared with poorly-fed ones. Given enough space to expand, therefore, well-fed colonies lose diversity and separate in space over a similar timescale to poorly fed ones. In sum, as long as there is some degree of nutrient limitation, we observe the emergence of structured communities. We conclude that resource-driven structuring is central to understanding both pattern and process in diverse microbial communities

International Frameworks Dealing with Human Risk Assessment of Combined Exposure to Multiple Chemicals

The development of harmonised terminology and frameworks for the human risk assessment of combined exposure to multiple chemicals (“chemical mixtures”) is an important area for EFSA and a number of activities have already been undertaken, i.e. in the fields of pesticides and contaminants. The first step prior to a risk assessment of combined exposure to multiple chemicals is problem formulation defining the relevant exposure, hazard and population to be considered. In practice, risk assessment of multiple chemicals is conducted using a tiered approach for exposure assessment, hazard assessment and risk characterisation. Higher tiers require increasing knowledge about the group of chemicals under assessment and the tiers can range from tier 0 (default values, data poor situation) to tier 3 (full probabilistic models). This scientific report reviews the terminology, methodologies and frameworks developed by national and international agencies for the human risk assessment of combined exposure to multiple chemicals and provides recommendations for future activities at EFSA in this area

Vilhelm Lundstedt’s ‘Legal Machinery’ and the Demise of Juristic Practice

This article aims to contribute to the academic debate on the general crisis faced by law schools and the legal professions by discussing why juristic practice is a matter of experience rather than knowledge. Through a critical contextualisation of Vilhelm Lundstedt’s thought under processes of globalisation and transnationalism, it is argued that the demise of the jurist’s function is related to law’s scientification as brought about by the metaphysical construction of reality. The suggested roadmap will in turn reveal that the current voiding of juristic practice and its teaching is part of the crisis regarding what makes us human

An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 2: impacts on organisms and ecosystems

New information on the lethal and sublethal effects of neonicotinoids and fipronil on organisms is presented in this review, complementing the previous WIA in 2015. The high toxicity of these systemic insecticides to invertebrates has been confirmed and expanded to include more species and compounds. Most of the recent research has focused on bees and the sublethal and ecological impacts these insecticides have on pollinators. Toxic effects on other invertebrate taxa also covered predatory and parasitoid natural enemies and aquatic arthropods. Little, while not much new information has been gathered on soil organisms. The impact on marine coastal ecosystems is still largely uncharted. The chronic lethality of neonicotinoids to insects and crustaceans, and the strengthened evidence that these chemicals also impair the immune system and reproduction, highlights the dangers of this particular insecticidal classneonicotinoids and fipronil. , withContinued large scale – mostly prophylactic – use of these persistent organochlorine pesticides has the potential to greatly decreasecompletely eliminate populations of arthropods in both terrestrial and aquatic environments. Sublethal effects on fish, reptiles, frogs, birds and mammals are also reported, showing a better understanding of the mechanisms of toxicity of these insecticides in vertebrates, and their deleterious impacts on growth, reproduction and neurobehaviour of most of the species tested. This review concludes with a summary of impacts on the ecosystem services and functioning, particularly on pollination, soil biota and aquatic invertebrate communities, thus reinforcing the previous WIA conclusions (van der Sluijs et al. 2015)

A comprehensive study of the high-pressure sulfidation effect on the active sites of CoMo(P)/Al2O3 sulfide catalysts

présentation M.A. Lelia

Towards the characterization of active phase of (Co)Mo sulfide catalyst under reaction conditions – Parallel between IR spectroscopy, HDS and HDN tests

International audienc

Isomerization of n-hexane over sulfated zirconia: influence of hydrogen and platinum

Isomerization of n-hexane (1–5 bar) is studied over sulfatedk zirconia at 423 K and 50 bar, under 5–45 bar hydrogen. The sulfated zirconia is crystallized at 923 K, then loaded with 0.025–0.8 wt% platinum. The isomerization rate first increases with hydrogen pressure, reaches a maximum, and finally decreases slowly. At a given platinum content, the position of the maximum increases with hexane pressure. The shape of the activity curves versus hydrogen partial pressure depends strongly on the platinum content. All the activity data are kinetically modeled by an acid mechanism in which the Lewis acid–base sites create carbenium ions. Activated hydrogen on platinum spills over to form the hydride species responsible for the desorption of the isocarbenium ions. The three parameters of the rate equation reflect the number of sites, the acid strength, and the efficiency of platinum. In the series of catalysts examined, the acidity is constant while the platinum efficiency increases with loading and reaches an upper limit at 0.15% platinum loading