A scaled down method for identifying the optimum range of L/S ratio in twin screw wet granulation using a regime map approach.

Twin screw wet granulation (TSWG) has gained momentum in the pharmaceutical industry for effective continuous granulation of solid dosage products. Liquid-to-solid (L/S) ratio is a key process parameter affecting granule properties. Identifying an optimum range of L/S ratio while reducing the number of full scale experiments can minimize material requirements and streamline formulation and process development.

Orientation dependence of the isoelectric point of TiO2 (rutile) surfaces.

The electroosmotic behavior of the rutile polymorph of titanium dioxide was explored as a function of the crystallographic orientation. Atomic force microscopy (AFM) was employed to make high-resolution force spectroscopy measurements between a silica sphere attached to a traditional, contact-mode AFM cantilever and TiO2(110), TiO2(100), and TiO2(001) surfaces in aqueous solutions. Measurements were taken in multiple solution conditions across a broad range of pH values, and the resultant force-distance curves were used to deduce relative behaviors of each orientation of rutile, with particular interest in changes of the isoelectric point (iep).

Zeta potential orientation dependence of sapphire substrates.

The zeta potential of planar sapphire substrates for three different crystallographic orientations was measured by a streaming potential technique in the presence of KCl and (CH3)4NCl electrolytes. The streaming potential was measured for large single crystalline C-plane (0001), A-plane (1120), and R-plane (1102) wafers over a full pH range at three or more ionic strengths ranging from 1 to 100 mM. The roughness of the epi-polished wafers was verified using atomic force microscopy to be on the order of atomic scale, and X-ray photoelectron spectroscopy (XPS) was used to ensure that the samples were free of silica and other contaminants.

The role of electrochemical reactions during electrophoretic particle deposition.

Platinum microelectrodes were fabricated on a sapphire substrate by lithographic patterning and used to manipulate 1.58 microm silica particles in the plane of the substrate. A digital video system captured the motion of particles far from the electrodes and their deposition onto the working electrode during application of a DC potential.