Catharina Knieke

Influence of Nanoparticle Reinforcement on the Mechanical Properties of Ultrafine-Grained Aluminium Produced by ARB

Dispersed nanoparticles are introduced from stabilized suspensions during the accumulative roll bonding process in aluminium AA1050A by air gun spraying up to a final volume fraction of 0.1 % after eight cycles. Additional strengthening caused by particle insertion is observed and strongly depends on the suspension medium and stabilizing agent as both influence interfacial bonding of the particles to the matrix. The particle insertion furthermore results in reduced peel strength of the sheets irrespective of particle material and size caused by a reduction of effective metal to metal bonding area during rolling through the presence of the particles.

Preparation of concentrated stable fenofibrate suspensions via liquid antisolvent precipitation

Abstract A major challenge in achieving size stability for relatively high concentration of fine particles from poorly water-soluble drug fenofibrate (FNB) is addressed through T-mixing based liquid antisolvent precipitation in the presence of ultrasonication and judicious use of stabilizers. Multiple stabilizers were screened in a batch mode prior to their continuous formation via T-mixing. In both cases, the stable suspensions maintained their size after 2 days of storage at room temperature, with the smallest particle size of d50: ∼1.2 µm was achieved through a combination of HPMC with SDS or PF-68. The influence of processing parameters, such as sonication energy, sonication probe insert depth and solvent/antisolvent flow rate, on the particle size distribution (PSD) in T-mixing were investigated, to identify optimum processing conditions. Optimal operating and formulation conditions also allowed increase in the drug loading from 0.32% to 4% (w/v), while keeping the median size 2.5 µm. Interestingly, the primary particles observed in the SEM were spherical and under 100 nm in diameter, indicating agglomeration. It was shown that the stabilized particles could be centrifuged and did not show size growth upon resuspension, allowing for increase in the drug loading up to 27% (w/v), which is a significant novel outcome.