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In recent years, azo dyes have received increasing attention due to their adverse effects on the environment and consumer health. However, the interaction mechanism between human serum albumin (HSA) and Direct Red 80 (DR80) is still unknown. The results showed that DR80 changed the secondary structure of HSA and made HSA skeleton loose and stretch. In addition, DR80 quenched the endogenous fluorescence of HSA by static quenching and changed the microenvironment of Trp in form of the hydrophobicity increased and the polarity decreased. Molecular docking results indicated that DR80 bound to the interface of three α-helical domains of HSA, hence, the changes in HSA structure and conformation was the main reason for the decline of its esterase activity. This work was done to illuminate the binding mechanism of DR80 and HSA, and to provide a different way for screening the low toxic dye at the molecular level.

In recent years, as the production and use of dyes have been greatly developed, the treatment of dye wastewater has become one of the current environmental problems that must be resolved. Ozone (O3) is a strong oxidant and is widely used in water treatment. In this study, the interaction process of ozone-treated Direct Red 80 (otDR80) and human serum albumin (HSA) was explored using multi-spectra methods. The results showed that otDR80 made the skeleton structure of HSA loosened and unfolded. OtDR80 changed the secondary structure of HSA, making the chromophore in the hydrophobic interior of HSA more tightly packed. The intensity of RLS spectra showed a upward trend after exposure to otDR80, indicating that the size of the reaction system increased. This study provides a new method for the degradation of DR80 and its toxicological study at the molecular level. study at the molecular level.

The chloride ingress is one of the most significant problems to reinforced concrete structures in coastal areas and cold regions where the de-icing salt is commonly used. In this paper, the lattice type model which has been widely used in fracture analysis of brittle materials is applied to simulate the chloride diffusion process in cementitious materials. The theoretical background of the lattice type model in solving the mass transport problem is briefly presented. The analytical solution of the Fick’s law is adopted to theoretically validate the developed lattice type model. After that, two typical case studies are included to demonstrate the application of the lattice type model in the chloride ingress issue. In the first case, the tortuosity effect of the aggregates on the chloride diffusion front at meso-scale is studied by the lattice model. In the second case, the lattice model is applied in the simulation of the chloride diffusion in cracked concrete. The results show that the lattice type model can be a useful tool to simulate the chloride ingress in the cementitious materials.

The mesoscopic simulation of behaviours of cementitious materials under different conditions has become a hot topic in academic research, as it provides more details to the mechanism study and structural design. To conduct a mesoscopic simulation, the meso-scale model of cementitious materials must be built. To ensure the precision of the aggregate shape in the simulated meso-scale model, key shape parameters of real aggregates should be identified. In this paper, an image-processing based method is proposed to detect the aspect ratio of a polygonal aggregate. The procedure and used algorithms are demonstrated in detail. As an application, totally about 1000 coarse aggregates from the Xinjiang, China are selected to identify the aspect ratio. It is found that the aspect ratio of coarse aggregates is a random variable following the Generalized Extreme Value (GEV) distribution. The published data by using the X-ray technique is also adopted as a comparison, and the results are almost the same as each other, which indicates that the aggregate source does not have an obvious effect on the probabilistic characteristics of the aspect ratio.