Jerry Y Y Heng

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The sensitivity of two techniques in tracking changes in surface energetics was investigated for a crystalline excipient, D-mannitol. Macroscopic crystals of D-mannitol were grown from saturated water solution by slow cooling, and sessile drop contact angle was employed to measure the anisotropic surface energy. The facet-specific surface energy was(More)
Inverse gas chromatography (IGC) is a widely used method for determining the dispersive component of the surface energy (gamma s (d)) of particulate and fibrous solids. Such measurements are normally conducted at very low solute concentrations (infinite dilution), and they result in a single numerical value of gamma s (d) for homogeneous materials which(More)
Triggered biodegradable composites made entirely from renewable resources are urgently sought after to improve material recyclability or be able to divert materials from waste streams. Many biobased polymers and natural fibers usually display poor interfacial adhesion when combined in a composite material. Here we propose a way to modify the surfaces of(More)
The wettability of the (001), (100), and (011) crystallographic facets of macroscopic aspirin crystals has been experimentally investigated using a sessile drop contact angle (theta) method. theta for a nonpolar liquid was very similar for all three facets, though significant theta differences were observed for three polar probe liquids. The observed(More)
The purpose of this study was to establish the link between the wetting behavior of crystalline pharmaceutical solids and the localized surface chemistry. A range of conventional wetting techniques were evaluated and compared with a novel experimental approach: sessile drop contact angle measurements on the individual facets of macroscopic (>1 cm) single(More)
Particulate interactions between drug and lactose carrier in dry powder inhaler formulations are affected by the heterogenous energy distribution on the surface of the individual compounds. A new method based on Inverse Gas Chromatography at finite concentration is applied to study the energy heterogeneity of untreated, milled, and recrystallized lactose of(More)
The effects of milling and particle size on surface energies of form I paracetamol crystals are reported. Paracetamol crystals (75–850 μm) were obtained by cooling methanol and acetone saturated solutions. Additionally, macroscopic (>2 cm) single crystals were grown by slow solvent evaporation from saturated solutions, ball milled and sieved into different(More)
Advancing (theta(A)) and receding (theta(R)) contact angles were measured with several probe liquids on the external facets (201), (001), (011), and (110) of macroscopic form I paracetamol crystals as well as the cleaved (internal) facet (010). For the external crystal facets, dispersive surface energies gamma(d) calculated from the contact angles were(More)
Milling and micronization of particles are routinely employed in the pharmaceutical industry to obtain small particles with desired particle size characteristics. The aim of this study is to demonstrate that particle shape is an important factor affecting the fracture mechanism in milling. Needle-shaped crystals of the β polymorph of D-mannitol were(More)
The effects of the blending of lactose fines to the overall adhesion property of coarse alpha-lactose monohydrate carrier particles were investigated. Five samples, three of them commercial samples from DOMO (Lactohale) LH100, LH210, and LH250) whilst the other two are blends of LH210 and LH250, were studied. Characterisation included particle sizing, SEM,(More)