A three-branch viscoelastic model based on fractional derivatives is proposed for the viscoelastic behaviours of solid propellants. The simulation results show a satisfactory agreement with the stress relaxation modulus and complex modulus of solid propellants. As a comparison, the static modulus is also characterized by traditional viscoelastic model with integer-order derivatives. Results show that the application of the fractional derivatives to the viscoelastic constitutive model can effectively reduce the number of the required parameters while giving an accurate prediction of viscoelastic behaviours of solid propellants. Moreover, a simple and effective direct search method based on simulated annealing and Powell's mothed is proposed for the data fitting. This article is part of the theme issue ‘Advanced materials modelling via fractional calculus: challenges and perspectives'.

No abstract

No abstract

A small chemical library of quinolone acid derivatives were synthesized as potential HIV-1 integrase inhibitors and evaluated their inhibition to the strand transfer process of HIV-1 integrase. Their structures were characterized by NMR, MS and HRMS. The result indicates that quinolone acid derivatives having 3,4,5-trihydroxylated aromatic substituent on the N-1 position of quinolone ring exhibit good inhibition with IC50 of 2.6 μM.

Six β-diketo derivatives of mono-substituted calix[4]arene were synthesized as potential HIV-1 integrase inhibitors and evaluated their inhibition to the strand transfer process of HIV-1 integrase. Their structures were characterized by NMR and HRMS. All the title compounds as potential HIV-1 integrase inhibitors proved to be active in the micromolar range (6.7–37.6 μM) on the strand transfer step.