Les effets des crèches fribourgeoises sur la socialisation des enfants de 2 à 5 ans

Cette recherche permet de savoir si les crèches fribourgeoises aident les enfants à se socialiser. Pour cela, nous avons recherché les avis de parents d’enfants placés en crèche et de spécialistes. Les résultats montrent des avantages tels que les apports des EDE, l’apprentissage des comportements sociaux, les relations et interactions, l’assimilation des règles, valeurs et codes sociaux, la préparation à l’école ainsi qu’une socialisation pour l’enfant unique. Deux inconvénients sont apparus durant la recherche : l’enfant fréquentant irrégulièrement la crèche ainsi que celui qui est placé trop tôt en collectivité. Cela peut rendre l’intégration de l’enfant difficile mais avec le savoir-faire des éducatrices cela s’améliore considérablement

Heat Treated NiP–SiC Composite Coatings: Elaboration and Tribocorrosion Behaviour in NaCl Solution

Tribocorrosion behaviour of heat-treated NiP and NiP–SiC composite coatings was investigated in a 0.6 M NaCl solution. The tribocorrosion tests were performed in a linear sliding tribometer with an electrochemical cell interface. It was analyzed the influence of SiC particles dispersion in the NiP matrix on current density developed, on coefficient of friction and on wear volume loss. The results showed that NiP–SiC composite coatings had a lower wear volume loss compared to NiP coatings. However, the incorporation of SiC particles into the metallic matrix affects the current density developed by the system during the tribocorrosion test. It was verified that not only the volume of co-deposited particles (SiC vol.%) but also the number of SiC particles per coating area unit (and consequently the SiC particles size) have made influence on the tribocorrosion behaviour of NiP–SiC composite coatings

Tribocorrosion behavior of beta titanium biomedical alloys in phosphate buffer saline solution

[EN] The tribo-electrochemical behavior of different β titanium alloys for biomedical applications sintered by powder metallurgy has been investigated. Different mechanical, electrochemical and optical techniques were used to study the influence of the chemical composition, Sn content, and the electrochemical conditions on the tribocorrosion behavior of those alloys Ti30NbxSn alloys (where x is the weight percentage of Sn content, 2% and 4%). Sn content increases the active and passive dissolution rate of the titanium alloys, thus increasing the mechanically activated corrosion under tribocorrosion conditions. It also increases the mechanical wear of the alloy. Prevailing electrochemical conditions between 1 and 2 V influences the wear accelerated corrosion by increasing it with the applied potential and slightly increases the mechanical wear of Ti30Nb4Sn. Wear accelerated corrosion can be predicted by existing models as a function of electrochemical and mechanical parameters of the titanium alloys.The authors would like to thank the Ministerio de Ciencia e Innovacion of the Spanish government for the financial support under the project MAT2011-22481.Guiñón Pina, V.; Dalmau, A.; Devesa, F.; Amigó Borrás, V.; Igual Muñoz, AN. (2015). Tribocorrosion behavior of beta titanium biomedical alloys in phosphate buffer saline solution. Journal of the Mechanical Behavior of Biomedical Materials. 46:59-68. https://doi.org/10.1016/j.jmbbm.2015.02.016S59684

Toxoplasma Effector MAF1 Mediates Recruitment of Host Mitochondria and Impacts the Host Response

Recent information has revealed the functional diversity and importance of mitochondria in many cellular processes including orchestrating the innate immune response. Intriguingly, several infectious agents, such as Toxoplasma, Legionella, and Chlamydia, have been reported to grow within vacuoles surrounded by host mitochondria. Although many hypotheses have been proposed for the existence of host mitochondrial association (HMA), the causes and biological consequences of HMA have remained unanswered. Here we show that HMA is present in type I and III strains of Toxoplasma but missing in type II strains, both in vitro and in vivo. Analysis of F1 progeny from a type II×III cross revealed that HMA is a Mendelian trait that we could map. We use bioinformatics to select potential candidates and experimentally identify the polymorphic parasite protein involved, mitochondrial association factor 1 (MAF1). We show that introducing the type I (HMA+) MAF1 allele into type II (HMA-) parasites results in conversion to HMA+ and deletion of MAF1 in type I parasites results in a loss of HMA. We observe that the loss and gain of HMA are associated with alterations in the transcription of host cell immune genes and the in vivo cytokine response during murine infection. Lastly, we use exogenous expression of MAF1 to show that it binds host mitochondria and thus MAF1 is the parasite protein directly responsible for HMA. Our findings suggest that association with host mitochondria may represent a novel means by which Toxoplasma tachyzoites manipulate the host. The existence of naturally occurring HMA+ and HMA- strains of Toxoplasma, Legionella, and Chlamydia indicates the existence of evolutionary niches where HMA is either advantageous or disadvantageous, likely reflecting tradeoffs in metabolism, immune regulation, and other functions of mitochondria. © 2014 Pernas et al

Aspects physico-chimiques de la tribocorrosion

La tribocorrosion résulte d’interactions entre phénomènes mécaniques et chimiques qui déterminent le comportement de systèmes tribologiques opérants dans un milieu corrosif. Ces interactions sont multiples et souvent complexes. D’une part la présence d’une couche passive à la surface d’un métal peut influencer l’usure et le frottement et d’autre part l’enlèvement de la couche passive par abrasion peut être à l’origine d’une importante dissolution du métal. Dans cet article, on discute de quelques mécanismes physico-chimiques de la tribocorrosion et on présente des exemples de problèmes de tribocorrosion traités par une approche physicochimique