Numerical simulation of high temperature corrosion processes in Mn, Cr, Si, Al – alloyed steel samples
The grain boundary oxidation mechanism in hot rolled steel samples during cooling from 500 °C – 800 °C down to room temperature was mathematically modeled. Given a fixed temperature ramp, the migration of the atomic species (iron, oxygen and the alloying elements) has been calculated with the parabolic rate equation for diffusion. After each small time step, the data was transferred into the database ChemApp (GTT-Technologies, Germany) to calculate the oxide composition for each point in thermodynamic equilibrium. The concentrations for each phase were illustrated in a phase map, similar to a cross section polish of the respective specimen. Total element concentration is shown as height plot to better pronounce the increased amount of oxidic phases along the grain boundaries. The obtained results are in good agreement with experimental data for low alloyed steel samples.
Phase Diagrams and Heterogeneous Equilibria: A Practical Introduction
1 Fundamental Facts and Concepts.- 2 Phase Equilibria in One-Component Systems.- 3 Phase Equilibria in Two-Component Systems Under Exclusion of the Gas Phase.- 4 Phase Equilibria in Three-Component Systems and Four-Component Systems with Exclusion of the Gas Phase.- 5 Phase Equilibria Including a Vapor Phase.- 6 Thermodynamics.- 7 Nucleation During Phase Transitions.- 8 Metastable Phases.- 9 Effect of Diffusion on Phase Transformations.- 10 Organic and Polymeric Materials.
Gut immunity in Lepidopteran insects.
Lepidopteran insects constitute one of the largest fractions of animals on earth, but are considered pests in their relationship with man. Key to the success of this order of insects is its ability to digest food and absorb nutrition, which takes place in the midgut. Because environmental microorganisms can easily enter Lepidopteran guts during feeding, the innate immune response guards against pathogenic bacteria, virus and microsporidia that can be devoured with food. Gut immune responses are complicated by both resident gut microbiota and the surrounding peritrophic membrane and are distinct from immune responses in the body cavity, which depend on the function of the fat body and hemocytes. Due to their relevance to agricultural production, studies of Lepidopteran insect midgut and immunity are receiving more attention, and here we summarize gut structures and functions, and discuss how these confer immunity against different microorganisms. It is expected that increased knowledge of Lepidopteran gut immunity may be utilized for pest biological control in the future.