Water-glass Module on Mechanical Properties of Geopolymer Recycled Aggregate Concrete

Geopolymer recycled aggregate concrete (GRAC) was prepared by replacing cement with geopolymer and natural aggregate with wast concrete. The effect of water-glass modules on mechanical properties of GRAC was studied. It was found that there are tow kind of binding structures in geopolymer hydration product: C-A-S-H and N-A-S-H, they both contribute to the strength of GRAC. The value of size conversion coefficient of current national standard is inapplicable for GRAC, the calculation method of which is given in this paper. Elasticity modulus and peak stress of GRAC is proportional to water-glass modulus, and peak strain is inversely proportional and its constitutive equation was established.

The Influence of Nanoparticles on Fire Retardancy of Pedunculate Oak Wood

Traditional flame retardants often contain halogens and produce toxic gases when burned. Hence, in this study, low-cost, environmentally friendly compounds that act as fire retardants are investigated. These materials often contain nanoparticles, from which TiO2 and SiO2 are the most promising. In this work, pedunculate oak wood specimens were modified with sodium silicate (Na2SiO3, i.e., water glass) and TiO2, SiO2, and ZnO nanoparticles using the vacuum-pressure technique. Changes in the samples and fire characteristics of modified wood were studied via thermal analysis (TA), infrared spectroscopy (FTIR), and scanning electron microscopy, coupled with energy-dispersive X-ray spectroscopy (SEM-EDX). The results of TA showed the most significant wood decomposition at a temperature of 350 °C, with a non-significant influence of the nanoparticles. A dominant effect of sodium silicate was observed in the main weight-loss step, resulting in a drop in decomposition temperature within the temperature range of 36–44 °C. More intensive decomposition of wood treated with water glass and nanoparticles led to a faster release of non-combustible gases, which slowed down the combustion process. The results demonstrated that wood modifications using sodium silicate and nanoparticle systems have potentially enhanced flame retardant properties.

Near-Wall Aggregation of Amyloidogenic Aβ 1-40 Peptide: Direct Observation by the FRET

The formation of amyloid fibrils is one of the variants of the self-organization of polypeptide chains. For the amyloid aggregation, the solution must be oversaturated with proteins. The interface of the liquid (solution) and solid (vessel walls) phases can trigger the adsorption of protein molecules, and the resulting oversaturation can initiate conformational transitions in them. In any laboratory experiment, we cannot exclude the presence of surfaces such as the walls of vessels, cuvettes, etc. However, in many works devoted to the study of amyloid formation, this feature is not considered. In our work, we investigated the behavior of the Aβ 1-40 peptide at the water–glass, water–quartz, and water–plastic interface. We carried out a series of simple experiments and showed that the Aβ 1-40 peptide is actively adsorbed on these surfaces, which leads to a significant interaction and aggregation of peptides. This means that the interface can be the place where the first amyloid nucleus appears. We suggest that this effect may also be one of the reasons for the difficulty of reproducing kinetic data when studying the aggregation of the amyloid of the Aβ 1-40 peptide and other amyloidogenic proteins

Preparation and Freeze-Thaw Resistance of Geopolymer-Based Natural Plant Fiber Composites

Slag, alkaline activator solution and straw fibers were used to manufacture geopolymer-based natural plant fiber composites. In this study, three influences of water glass modulus, fiber content and water-binder ratio on bending strength were studied by orthogonal experiment and single factor analysis. The results indicate that the order of the factors affecting the bending strength is: water-binder ratio > fiber content > water glass modulus. When the water-binder ratio is 0.4, the fiber content is 12%, and the water glass modulus is 1.9, the bending strength of composite is up to 9.1MPa, which exceeds the standard requirements (9MPa) for qualified products specified in the standard (GB/T 24312-2009). The SEM and appearance of specimens indicate that the geopolymer-based natural plant fiber composites have good freeze-thaw resistance.