Investigation on Purine Corrosion Inhibitions via Quantum Chemical Calculation

Corrosion inhibition performances of three purine derivatives were investigated systematically by employing DFT and molecular modeling.The relationship between macroscopic inhibition efficiency and quantum chemical properties was discussed from multiple perspectives,based on frontier orbital theory,and Fukui function theories.Comparative experimental and theoretical studies were taken,indicating the inhibition efficiency could be analyzed in the order of guanine<2,6-diaminopurine<2,6-dithiopurine.The sulphur atom(S5)was validated to be the most susceptible site for electrophile via quantitative surface analysis.

Spontaneous hierarchical surface engineering of minerals through coupled dissolution-precipitation chemistry

Peculiar hierarchical microstructures in creatures inspire modern material design with distinct functionalities.Creatures can effortlessly construct sophisticated yet long-range ordered microstructure across bio-membrane through ion secretion and precipitation.However,microstructure biomimicry in current technology generally requires elaborate,point-by-point fabrication.Herein,a spontaneous yet controllable strategy is developed to achieve surface microstructure engineering through a natural surface phenomenon similar to ion secretion-precipitation,that is,coupled dissolution-precipitation.A series of hierarchical microstructures on mineral surfaces in fluids with tunable morphology,orientation,dimension,and spatial distribution are achieved by simply controlling initial dissolution and fluid chemistry.In seawater,long-range ordered film of vertically aligned brucite flakes forms through interfacial dissolution,nucleation,and confinement-induced orientation of flakes with vertically grown{110}plane,on the edge of which,fusiform aragonite epitaxially precipitates.With negligible initial surface dissolution,prismatic aragonite epitaxially grows on a calcite polyhedron-packed surface.By tuning fluid chemistry,closely packed calcite polyhedron and loosely packed calcite micro-pillars are engineered through rapid and retarded precipitation,respectively.Surprisingly,the spontaneously grown microstructures resemble those deliberately created by human or found in nature,and tremendously modulate surface functionality.These findings open new possibilities for facile and customizable engineering of microstructural surfaces,hierarchical heterostructures,and biomimetic materials.

An Internal Expansive Stress Model of Concrete under Sulfate Attack

Concrete experiences expansive deformation during sulfate attack due to internal expansive stress. Sulfate ions enter concrete pores, react with the pore solution, and produce ettringite. The production of ettringite explains the internal expansive stress that reduces the durability of concrete. In this study, the model of internal expansive stress was achieved through the Eshelby＇s theory, as well as the experimental results for concrete erosion. Numerical simulation indicated that internal expansive stress is not only determined by the water-to-cement ratio of concrete and the concentration of sulfate solution, but also affected by the relaxation time of concrete.