Strengthening Silicate Coatings on Quartz Particles with the Addition of Aluminum Phosphate

For aesthetic purposes, quartz particles are coated to provide a wide array of colored sands. These colored sands are used extensively in roofing shingles and pool plasters. The coating is a proprietary mixture whose base is sodium silicate. Sodium silicate solutions are also referred to as water glass. Upon heating to remove water, a hard amorphous silicon dioxide coating is left behind. This coating is rugged but not a tough as crystalline quartz. This study investigates the use of Goldschmidt’s rules of substitution, a fundamental theory from geochemistry, to enhance the coating of the quartz particles. Aluminum phosphate was chosen as a potential hardener based on its ability to undergo coupled substitution in the silica lattice. Hardness was determined through scratch test and increased bond strength confirmed through FTIR. Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) was used to monitor the escape of toxic heavy metals from the coating into surrounding water. The increase in strength and durability as well as the modified coatings ability to inhibit the loss of toxic metals through solubilization are reported

Chimpanzee histology and functional brain imaging show that the paracingulate sulcus is not human-specific

International audienceAbstract The paracingulate sulcus -PCGS- has been considered for a long time to be specific to the human brain. Its presence/absence has been discussed in relation to interindividual variability of personality traits and cognitive abilities. Recently, a putative PCGS has been observed in chimpanzee brains. To demonstrate that this newly discovered sulcus is the homologue of the PCGS in the human brain, we analyzed cytoarchitectonic and resting-state functional magnetic resonance imaging data in chimpanzee brains which did or did not display a PCGS. The results show that the organization of the mid-cingulate cortex of the chimpanzee brain is comparable to that of the human brain, both cytoarchitectonically and in terms of functional connectivity with the lateral frontal cortex. These results demonstrate that the PCGS is not human-specific but is a shared feature of the primate brain since at least the last common ancestor to humans and great apes ~6 mya

Quantitative analysis of the myelin g-ratio from electron microscopy images of the macaque corpus callosum

We provide a detailed morphometric analysis of eight transmission electron micrographs (TEMs) obtained from the corpus callosum of one cynomolgus macaque. The raw TEM images are included in the article, along with the distributions of the axon caliber and the myelin g-ratio in each image. The distributions are analyzed to determine the relationship between axon caliber and g-ratio, and compared against the aggregate metrics (myelin volume fraction, fiber volume fraction, and the aggregate g-ratio), as defined in the accompanying research article entitled ‘In vivo histology of the myelin g-ratio with magnetic resonance imaging’ (Stikov et al., NeuroImage, 2015)