Flow-to-fracture transition and pattern formation in a discontinuous shear thickening fluid

Recent theoretical and experimental work suggests a frictionless-frictional transition with increasing inter-particle pressure explains the extreme solid-like response of discontinuous shear thickening suspensions. However, analysis of macroscopic discontinuous shear thickening flow in geometries other than the standard rheometry tools remain scarce. Here we use a Hele-Shaw cell geometry to visualise gas-driven invasion patterns in discontinuous shear thickening cornstarch suspensions. We plot quantitative results from pattern analysis in a volume fraction-pressure phase diagram and explain them in context of rheological measurements. We observe three distinct pattern morphologies: viscous fingering, dendritic fracturing, and system-wide fracturing, which correspond to the same packing fraction ranges as weak shear thickening, discontinuous shear thickening, and shear-jammed regimes

A randomised clinical study to determine the effect of a toothpaste containing enzymes and proteins on plaque oral microbiome ecology

The numerous species that make up the oral microbiome are now understood to play a key role in establishment and maintenance of oral health. The ability to taxonomically identify community members at the species level is important to elucidating its diversity and association to health and disease. We report the overall ecological effects of using a toothpaste containing enzymes and proteins compared to a control toothpaste on the plaque microbiome. The results reported here demonstrate that a toothpaste containing enzymes and proteins can augment natural salivary defences to promote an overall community shift resulting in an increase in bacteria associated with gum health and a concomitant decrease in those associated with periodontal disease. Statistical analysis shows significant increases in 12 taxa associated with gum health including Neisseria spp. and a significant decrease in 10 taxa associated with periodontal disease including Treponema spp. The results demonstrate that a toothpaste containing enzymes and proteins can significantly shift the ecology of the oral microbiome (at species level) resulting in a community with a stronger association to health

Difficultés d'aménagement d'un plan d'eau en site calcaire

The Gourdon dam is a small installation of touristic interest built on a highly impervious calcareous substrate. The dam has been used for ten years. Today, it is one the main pieces of touristic interest in the city of Gourdon. This article describes chronologically the problems encountered during its construction and the tightness of the reservoir and describes the repercussion of these projects on the entire installation cost. / Le barrage de Gourdon est un petit ouvrage d'intérêt touristique aménagé sur un substrat calcaire très imperméable. Le barrage est en service depuis dix ans. Il constitue, aujourd'hui, l'une des pièces maîtresse de l'équipement touristique de la commune de Gourdon. L'article relate chronologiquement les difficultés de réalisation du barrage et du traitement d'étanchéité de la retenue et précise l'incidence des travaux d'imperméabilisation de la cuvette sur le coût du projet

Unité Mobile Gériatrique du CHU de Limoges : intégration de la filière gériatrique depuis les urgences et dans les services non gériatriques.

National audienc

Analysis of the response of human keratinocytes to Malassezia globosa and restricta strains.

Malassezia spp. are saprophyte yeasts involved in skin diseases with different degrees of severity. The aim of our study was to analyze the response of human epidermal keratinocytes to Malassezia globosa and restricta strains evaluating the host defence mechanisms induced by Malassezia spp. colonization. Our results showed a different modulation of the inflammatory and immunomodulatory cytokine pathways obtained with the different strains of Malassezia tested. In addition, this expression is altered by blocking the TLR2 receptor. In comparison with M. furfur, M. globosa and restricta displayed an unexpected and striking cytotoxicity on keratinocytes. The differences observed could be related to the different modalities of interaction between keratinocytes and Malassezia strains, but also to their growth condition. Taken together, these results indicate that M. globosa or M. restricta colonization exert a different control on the cytokine inflammatory response activated in the human keratinocyte in which TLR2 might be involved. M. globosa and M. restricta may play a synergistic role in the exacerbation of skin diseases in which both are found

An anisotropic model for the electrical resistivity of two-phase geologic materials

Electrical and electromagnetic surveys of the seafloor provide valuable information about the macro and microscopic properties of subseafloor sediments. Sediment resistivity is highly variable and governed by a wide range of properties including pore-fluid salinity, pore-fluid saturation, porosity, pore geometry, and temperature. A new anisotropic, twophase, effective medium model describes the electrical resistivity of porous rocks and sediments. The only input parameters required are the resistivities of the solid and fluid components, their volume fractions and grain shape. The approach makes use of the increase in path length taken by an electrical current through an idealized granular medium comprising of aligned ellipsoidal grains. The model permits both solid and fluid phases to have a finite conductivity useful for dealing with surface charge conduction effects associated with clay minerals and gives results independent of grain size hence, valid for a wide range of sediment types. Furthermore, the model can be used to investigate the effects of grain aspect ratio and alignment on electrical resistivity anisotropy. Good agreement was found between the model predictions and laboratory measurements of resistivity and porosity on artificial sediments with known physical properties

Chemical organization of the cell wall polysaccharide core of Malassezia restricta.

International audienceMalassezia species are ubiquitous residents of human skin and are associated with several diseases such as seborrheic dermatitis, tinea versicolor, folliculitis, atopic dermatitis, and scalp conditions such as dandruff. Host-Malassezia interactions and mechanisms to evade local immune responses remain largely unknown. Malassezia restricta is one of the most predominant yeasts of the healthy human skin, its cell wall has been investigated in this paper. Polysaccharides in the M. restricta cell wall are almost exclusively alkali-insoluble, showing that they play an essential role in the organization and rigidity of the M. restricta cell wall. Fractionation of cell wall polymers and carbohydrate analyses showed that the polysaccharide core of the cell wall of M. restricta contained an average of 5% chitin, 20% chitosan, 5% β-(1,3)-glucan, and 70% β-(1,6)-glucan. In contrast to other yeasts, chitin and chitosan are relatively abundant, and β-(1,3)-glucans constitute a minor cell wall component. The most abundant polymer is β-(1,6)-glucans, which are large molecules composed of a linear β-(1,6)-glucan chains with β-(1,3)-glucosyl side chain with an average of 1 branch point every 3.8 glucose unit. Both β-glucans are cross-linked, forming a huge alkali-insoluble complex with chitin and chitosan polymers. Data presented here show that M. restricta has a polysaccharide organization very different of all fungal species analyzed to date