Densification of the interlayer spacing governs the nanomechanical properties of calcium-silicate-hydrate

Calciuam-silicate-hydrate (C-S-H) is the principal binding phase in modern concrete. Molecular simulations imply that its nanoscale stiffness is ‘defect-driven’, i.e., dominated by crystallographic defects such as bridging site vacancies in its silicate chains. However, experimental validation of this result is difficult due to the hierarchically porous nature of C-S-H down to nanometers. Here, we integrate high pressure X-ray diffraction and atomistic simulations to correlate the anisotropic deformation of nanocrystalline C-S-H to its atomic-scale structure, which is changed by varying the Ca-to-Si molar ratio. Contrary to the ‘defect-driven’ hypothesis, we clearly observe stiffening of C-S-H with increasing Ca/Si in the range 0.8 ≤ Ca/Si ≤ 1.3, despite increasing numbers of vacancies in its silicate chains. The deformation of these chains along the b-axis occurs mainly through tilting of the Si-O-Si dihedral angle rather than shortening of the Si-O bond, and consequently there is no correlation between the incompressibilities of the a- and b-axes and the Ca/Si. On the contrary, the intrinsic stiffness of C-S-H solid is inversely correlated with the thickness of its interlayer space. This work provides direct experimental evidence to conduct more realistic modelling of C-S-H-based cementitious material

Dietary Whey Proteins Shield Murine Cecal Microbiota From Extensive Disarray Caused By A High-fat Diet

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)High-fat diets are used to induce adverse alterations in the intestinal microbiota, or dysbiosis, generalized inflammation and metabolic stress, which ultimately may lead to obesity. The influence of dietary whey proteins, whether intact or hydrolyzed, has been reported to improve glucose homeostasis and reduce stress. Therefore, the purpose of this work was to test if dietary milk-whey proteins, both in the intact form and hydrolyzed, could have an effect on the compositional changes of the cecal microbiota that can be induced in mice when receiving a high-fat diet in combination with the standard casein. Male C57BL/6 mice were fed a control casein diet (AIN 93-G); high-fat-casein (HFCAS); high-fat-whey protein concentrate (HFWPC) and high-fat whey protein hydrolysate (HFWPH) for 9 weeks. The intestinal microbiota composition was analyzed by 16S-rRNA of the invariant (V1-V3) gene, potentially endotoxemic lipopolysaccharide (LPS) release was determined colorimetrically, and liver fat infiltration assessed by light microscopy. The high-fat diet proved to induce dysbiosis in the animals by inverting the dominance of the phylum Firmicutes over Bacteroidetes, promoted the increase of LPS and resulted in liver fat infiltration. The whey proteins, whether intact or hydrolyzed, resisted the installation of dysbiosis, prevented the surge of circulating LPS and prevented fat infiltration in the liver. It is concluded that dietary whey proteins exert metabolic actions that tend to preserve the normal microbiota profile, while initigating liver fat deposition in mice consuming a high-fat diet for nine weeks. Such beneficial effects were not seen when casein was the dietary protein. The hydrolyzed whey protein still differed from the normal whey protein by selectively protecting the Bacteroidetes phylum. (C) 2016 Elsevier Ltd. All rights reserved.85121130Fundacao de Amparo a Pesquisa do Estado de Sao Paulo - FAPESP [2012/05859-7, 2013/02862-0]CNPq [573856/2008-7]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq