System failure analysis based on DEMATEL–ISM and FMECA

A new method of system failure analysis was proposed. First, considering the relationships between the failure subsystems,the decision making trial and evaluation laboratory(DEMATEL) method was used to calculate the degree of correlation between the failure subsystems, analyze the combined effect of related failures, and obtain the degree of correlation by using the directed graph and matrix operations. Then, the interpretative structural modeling(ISM) method was combined to intuitively show the logical relationship of many failure subsystems and their influences on each other by using multilevel hierarchical structure model and obtaining the critical subsystems. Finally, failure mode effects and criticality analysis(FMECA) was used to perform a qualitative hazard analysis of critical subsystems, determine the critical failure mode, and clarify the direction of reliability improvement.Through an example, the result demonstrates that the proposed method can be efficiently applied to system failure analysis problems.

Molecular Modification of Benzophenone Derivatives for Lower Bioenrichment and Toxicity Through the Pharmacophore Model

In this study,we used the improved extreme-difference normalization method to calculate the comprehensive evaluation values of bioenrichment and toxicity of benzophenone UV light absor-bers(BPs).Based on this parameter,a 3D-QSAR(QSAR=quantitative structure activity relationship)pharmacophore model was constructed using Discovery Studio software and applied to the mole-cular modification of BPs.With three commonly used ingredients in sunscreen 2-hydroxy-4-methoxybenzophenone(BP-3),2,2'-dihydroxy-4,4'-dimethoxybenzophenone(BP-6)and 2,2'-dihydroxy-4-methoxybenzophenone(BP-8)as target molecules,we performed BPs substitution reaction based on the binding positions of characteristic elements of the pharmacophore model and designed BP derivatives with reduced bioenrichment and toxicity.Stability and function evaluation showed that while the stability of 6 BP derivatives was enhanced,the light absorption capacity was also significantly enhanced(from 9.16%to 43.16%).Molecular dynamics simulation results showed that the binding ability of BP-609 molecule with serum albumin was reduced by 16.37%compared with BP-6,and the binding with collagen could not occur spontaneously,which could be used as an explanation for the simultaneous reduction of its bioenrichment and toxicity.Besides,through the simulation of human metabolism,it was found that the liver metabolites of BP-609 were less toxic,which reduced the potential risk of human metabolism.It proved that the molecular modification scheme of BPs was environment-friendly.