Facile Preparation of Danazol Nanoparticles by High-Gravity Anti-solvent Precipitation （HGAP） Method

The nanoparticles of the hydrophobic drug of danazol with narrow size distribution are facilely prepared by controlled high-gravity anti-solvent precipitation(HGAP) process.Intensified micromixing and uniform nucleation environment are created by the high-gravity equipment(rotating packed bed) in carrying out the anti-solvent precipitation process to produce nanoparticles.The average particle size decreases from 55 μm of the raw danazol to 190 nm of the nanoparticles.The Brunauer-Emmett-Teller(BET) surface area sharply increases from 0.66 m2·g-1 to 15.08 m2·g-1.Accordingly,the dissolution rate is greatly improved.The molecular state,chemical composition,and crystal form of the danazol nanoparticles remains unchanged after processing according to Fourier transform infrared(FTIR) and X-ray diffraction(XRD).The high recovery ratio and continuous production capacity are highly appreciated in industry.Therefore,the HGAP method might offer a general and facile platform for mass production of hydrophobic pharmaceutical danazol particles in nanometer range.

Low Temperature One Step Synthesis of Barium Titanate: Particle Formation Mechanism and Large-scale Synthesis

The formation of BaTiO3 nanoparticles via the reaction of BaCl2, TiCl4 and NaOH in aqueous solution has been systematically studied. The formation of BaTiO3 from the ionic precursors has been elucidated to be a very rapid process, occurring at temperature higher than 60℃. Furthermore, the particle size could be controlled by the proper selection of the synthesis conditions (e.g. reactant concentration of 0.5—1.0mol·L-1, temperature of 80— 95℃ and pH≥13). A two-step precipitation mechanism was proposed. The first stage of the synthesis involved the formation of amorphous Ti-rich gel phase. The second stage of the synthesis was the reaction between the amor-phous phase and the solution-based Ba2+ ions, which led to the crystallization of BaTiO3. Based on the particle for-mation mechanism, a novel method, high gravity reactive precipitation, was proposed and used to mass production of BaTiO3 of average particle size of about 60 nm and with narrow particle size distribution. Because it could break up the amorphous Ti-rich gel into small pieces, intensify mass transfer, promote the reaction rate of amorphous Ti-rich gel with Ba2+ ions.