How Tuning Interfaces Impacts the Dynamics and Structure of Polymer Nanocomposites Simultaneously

Fundamental understanding of macroscopic properties of polymer nanocomposites (PNCs) remains difficult due to the complex interplay of microscopic dynamics and structure, namely interfacial layer relaxations and three-dimensional nanoparticle arrangements. The effect of surface modification by alkyl methoxysilanes at different grafting densities has been studied in PNCs made of poly(2-vinylpyridine) and spherical 20 nm silica nanoparticles (NPs). The segmental dynamics has been probed by broadband dielectric spectroscopy, and the filler structure by small-angle X-ray scattering and reverse Monte Carlo simulations. By combining the particle configurations with the interfacial layer properties, it is shown how surface modification tunes the attractive polymer-particle interactions: bare NPs slow down the polymer interfacial layer dynamics over a thickness of ca. 5 nm, while grafting screens these interactions. Our analysis of interparticle spacing and segmental dynamics provides unprecedented insight into the effect of surface modification on the main characteristics of PNCs: particle interactions and polymer interfacial layers

La terre crue, matériau universel

Disponible, plastique, recyclable, la terre convient pour bâtir toutes formes et dimensions de constructions. Mais qu’en est-il de l’évolution de ces techniques constructives et de l’intérêt que les populations anciennes comme actuelles lui portent de par le monde ? © Romain Etienne/ITEM Hubert Guillaud Lorsque j’ai commencé à m’intéresser à la construction en terre, c’était en lien avec les questions d’énergie, à la suite de la crise des années 1970. Les seules alternatives qui se développa..

Plasmacytoid Dendritic Cell Infection and Sensing Capacity during Pathogenic and Nonpathogenic Simian Immunodeficiency Virus Infection.

International audienceHuman immunodeficiency virus (HIV) in humans and simian immunodeficiency virus (SIV) in macaques (MAC) lead to chronic inflammation and AIDS. Natural hosts, such as African green monkeys (AGM) and sooty mangabeys (SM), are protected against SIV-induced chronic inflammation and AIDS. Here, we report that AGM plasmacytoid dendritic cells (pDC) express extremely low levels of CD4, unlike MAC and human pDC. Despite this, AGM pDC efficiently sensed SIVagm, but not heterologous HIV/SIV isolates, indicating a virus-host adaptation. Moreover, both AGM and SM pDC were found to be, in contrast to MAC pDC, predominantly negative for CCR5. Despite such limited CD4 and CCR5 expression, lymphoid tissue pDC were infected to a degree similar to that seen with CD4(+) T cells in both MAC and AGM. Altogether, our finding of efficient pDC infection by SIV in vivo identifies pDC as a potential viral reservoir in lymphoid tissues. We discovered low expression of CD4 on AGM pDC, which did not preclude efficient sensing of host-adapted viruses. Therefore, pDC infection and efficient sensing are not prerequisites for chronic inflammation. The high level of pDC infection by SIVagm suggests that if CCR5 paucity on immune cells is important for nonpathogenesis of natural hosts, it is possibly not due to its role as a coreceptor. The ability of certain key immune cell subsets to resist infection might contribute to the asymptomatic nature of simian immunodeficiency virus (SIV) infection in its natural hosts, such as African green monkeys (AGM) and sooty mangabeys (SM). This relative resistance to infection has been correlated with reduced expression of CD4 and/or CCR5. We show that plasmacytoid dendritic cells (pDC) of natural hosts display reduced CD4 and/or CCR5 expression, unlike macaque pDC. Surprisingly, this did not protect AGM pDC, as infection levels were similar to those found in MAC pDC. Furthermore, we show that AGM pDC did not consistently produce type I interferon (IFN-I) upon heterologous SIVmac/HIV type 1 (HIV-1) encounter, while they sensed autologous SIVagm isolates. Pseudotyping SIVmac/HIV-1 overcame this deficiency, suggesting that reduced uptake of heterologous viral strains underlays this lack of sensing. The distinct IFN-I responses depending on host species and HIV/SIV isolates reveal the host/virus species specificity of pDC sensing

Discovery and mapping of a new expressed sequence tag-single nucleotide polymorphism and simple sequence repeat panel for large-scale genetic studies and breeding of Theobroma cacao L.

Theobroma cacao is an economically important tree of several tropical countries. Its genetic improvement is essential to provide protection against major diseases and improve chocolate quality. We discovered and mapped new expressed sequence tag-single nucleotide polymorphism (EST-SNP) and simple sequence repeat (SSR) markers and constructed a high-density genetic map. By screening 149 650 ESTs, 5246 SNPs were detected in silico, of which 1536 corresponded to genes with a putative function, while 851 had a clear polymorphic pattern across a collection of genetic resources. In addition, 409 new SSR markers were detected on the Criollo genome. Lastly, 681 new EST-SNPs and 163 new SSRs were added to the pre-existing 418 co-dominant markers to construct a large consensus genetic map. This high-density map and the set of new genetic markers identified in this study are a milestone in cocoa genomics and for marker-assisted breeding. The data are available at http://tropgenedb.cirad.fr

Excessive Unbalanced Meat Consumption in the First Year of Life Increases Asthma Risk in the PASTURE and LUKAS2 Birth Cohorts.

A higher diversity of food items introduced in the first year of life has been inversely related to subsequent development of asthma. In the current analysis, we applied latent class analysis (LCA) to systematically assess feeding patterns and to relate them to asthma risk at school age. PASTURE (N=1133) and LUKAS2 (N=228) are prospective birth cohort studies designed to evaluate protective and risk factors for atopic diseases, including dietary patterns. Feeding practices were reported by parents in monthly diaries between the 4th and 12th month of life. For 17 common food items parents indicated frequency of feeding during the last 4 weeks in 4 categories. The resulting 153 ordinal variables were entered in a LCA. The intestinal microbiome was assessed at the age of 12 months by 16S rRNA sequencing. Data on feeding practice with at least one reported time point was available in 1042 of the 1133 recruited children. Best LCA model fit was achieved by the 4-class solution. One class showed an elevated risk of asthma at age 6 as compared to the other classes (adjusted odds ratio (aOR): 8.47, 95% CI 2.52-28.56, p = 0.001) and was characterized by daily meat consumption and rare consumption of milk and yoghurt. A refined LCA restricted to meat, milk, and yoghurt confirmed the asthma risk effect of a particular class in PASTURE and independently in LUKAS2, which we thus termed unbalanced meat consumption (UMC). The effect of UMC was particularly strong for non-atopic asthma and asthma irrespectively of early bronchitis (aOR: 17.0, 95% CI 5.2-56.1, p < 0.001). UMC fostered growth of iron scavenging bacteria such as Acinetobacter (aOR: 1.28, 95% CI 1.00-1.63, p = 0.048), which was also related to asthma (aOR: 1.55, 95% CI 1.18-2.03, p = 0.001). When reconstructing bacterial metabolic pathways from 16S rRNA sequencing data, biosynthesis of siderophore group nonribosomal peptides emerged as top hit (aOR: 1.58, 95% CI 1.13-2.19, p = 0.007). By a data-driven approach we found a pattern of overly meat consumption at the expense of other protein sources to confer risk of asthma. Microbiome analysis of fecal samples pointed towards overgrowth of iron-dependent bacteria and bacterial iron metabolism as a potential explanation

Continuous Rather Than Solely Early Farm Exposure Protects From Hay Fever Development

BACKGROUND: An important window of opportunity for early-life exposures has been proposed for the development of atopic eczema and asthma.OBJECTIVE: However, it is unknown whether hay fever with a peak incidence around late school age to adolescence is similarly determined very early in life.METHODS: In the Protection against Allergy-Study in Rural Environments (PASTURE) birth cohort potentially relevant exposures such as farm milk consumption and exposure to animal sheds were assessed at multiple time points from infancy to age 10.5 years and classified by repeated measure latent class analyses (n [ 769). Fecal samples at ages 2 and 12 months were sequenced by 16S rRNA. Hay fever was defined by parent -reported symptoms and/or physician's diagnosis of hay fever in the last 12 months using questionnaires at 10.5 years.RESULTS: Farm children had half the risk of hay fever at 10.5 years (adjusted odds ratio [aOR] 0.50; 95% CI 0.31-0.79) than that of nonfarm children. Whereas early life events such as gut microbiome richness at 12 months (aOR 0.66; 95% CI 0.46-0.96) and exposure to animal sheds in the first 3 years of life (aOR 0.26; 95% CI 0.06-1.15) were determinants of hay fever, the continuous consumption of farm milk from infancy up to school age was necessary to exert the protective effect (aOR 0.35; 95% CI 0.17-0.72).CONCLUSIONS: While early life events determine the risk of subsequent hay fever, continuous exposure is necessary to achieve protection. These findings argue against the notion that only early life exposures set long-lasting trajectories. (c) 2022 The Authors. Published by Elsevier IncPeer reviewe

Maturation of the gut microbiome during the first year of life contributes to the protective farm effect on childhood asthma

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