Milling Protocol Research Articles

Toward Phase Quantification at the Nanoscale Using the Total Scattering Pair Distribution Function (TSPDF) Method: Recrystallization of Cryomilled Sulfamerazine

One of the most challenging problems facing the pharmaceutical industry is to identify and quantify the phase fractions in mixed phase samples that contain crystalline, nanocrystalline, and amorphous components. Here we demonstrate an approach that accomplishes this using high energy X-rays coupled with total scattering pair distribution function (TSPDF) analysis by studying samples of sulfamerazine, a sulfonamide antibiotic drug, recrystallizing from a cryomilled-induced amorphous state. Samples milled under different conditions were shown to have significantly different phase compositions. The initial amorphous state was obtained by cryomilling the stable Form 1 polymorph. This was then aged at low temperature to initiate controlled recrystallization. We show that depending on the milling and aging protocol we see a mixture of amorphous material with the metastable Form 2 polymorph. A minority of Form 1 is also observed. We describe the approach that allowed us to quantify the phase fractions despite the majority of the sample lacking crystalline order.

The composition and ultrastructure of sorghum spent grains

The present study aimed to investigate the composition and structure of sorghum spent grains (SSG) as a pre-requisite for evaluating potential applications of this brewery co-product. SSG samples sourced from African breweries employing a grist with a proportion of a hammer milled-unmalted sorghum (Sorghum vulgare cv. Fara Fara) were found to be heterogeneous materials containing remnants of intact grains, and with particles ranging in size from 2 mm. Samples contained a considerable amount of residual starch (4.6–10.0% d.b.), much higher than typically reported for barley-derived spent grains. This probably arises from the use of grists high in unmalted sorghum, but indicates that improvements in brewing process efficiency could be achieved with improvements, for example, in milling and mashing protocols. The crude protein content of the SSG samples was unexpectedly high (38.0–41.2% d.b.), indicating that this material would have potential value as an animal feed or source of refined protein. Potential reasons for this higher than expected residual protein content are discussed. The remainder of SSG gross composition (mean of five samples) was cellulose (11.4% d.b.), hemicellulose (17.3% d.b.), lipid (8.5% d.b.), lignin (9.4% d.b.) and ash (4.46% d.b.), with a total mass recovery of close to 98% represented by all analysed components. Copyright © 2013 The Institute of Brewing & Distilling

High alkylation activities of ball-milled synthesized low-load supported iron oxide nanoparticles on mesoporous aluminosilicates

Low-load iron oxide nanoparticles on Al-SBA-15 prepared using a novel dry milling approach exhibited excelling activities in the microwave-assisted akylation of toluene with benzyl chloride (Lewis acids promoted reaction) and benzyl alcohol (Brönsted acids promoted reaction) as compared to the parent Al-SBA-15 and similar iron oxide nanoparticles supported on Al-MCM-41 materials. Materials prepared using the milling protocol possessed remarkably low iron loadings (<0.1wt%) but featured highly accessible sites and small nanoparticle sizes that seemed to be related to the observed differences in activities in the systems.

Mechanochemical Approaches to Ceramic Ink Formulation for Digital Fabrication of Solid Oxide Fuel Cells

Four different ink processing protocols were investigated to control the particle size distribution of lab scale batches of inkjet inks used for printing Solid Oxide Fuel Cell (SOFC) anodes. The inks were composed of a mixture of commercial Nickel Oxide (NiO) and Yttria-stabilized Zirconia (YSZ) powders dispersed in organic solvents. Protocols incorporating high energy wet and dry milling using a SPEX 8000 mixer mill were compared to traditional low energy milling/dispersion methods. Brunauer-Emmett-Teller (B.E.T.) surface area measurements were used in conjunction with scanning electron microscopy (S.E.M.) to determine the effects of the milling protocols on the dry powder particle sizes and morphologies. Dynamic light scattering (D.L.S.) was used to measure the particle size distributions of the inks. Low energy dispersion of the NiO and YSZ powders produced an ink with a number weighted particle size distribution peaked &#x223C; 300 nm and a significant tail of particles as large as 1 &#x3BC;m. Adding high energy dry milling or high energy slurry dispersion to the process removed most of the large particle size tail, but the particle size distribution remained peaked at 250 &#x2013; 300 nm. By combining high energy dry powder milling with high energy slurry dispersion, the main peak in the particle size distribution shifted to 180 nm with minimal particles above 600 nm. These results indicate that the combination of high energy milling and dispersion enable lab scale production of nanoscale NiO/YSZ inks from commercial powders. The protocols developed in this work provide a first step towards the goal of controlling the microstructure of inkjet printed solid oxide fuel cell (SOFC) anodes through control of the ink particle size distribution.

Focused-ion-beam Milling: A Novel Approach to Probing the Interior of Particles Used for Inhalation Aerosols

The current study aimed to examine the pharmaceutical applications of the focused-ion-beam (FIB) in the inhalation aerosol field, particularly to particle porosity determination (i.e. percentage of particles having a porous interior). The interior of various spray dried particles (bovine serum albumin (BSA) with different degrees of surface corrugation, mannitol, disodium cromoglycate and sodium chloride) was investigated via FIB milling at customized conditions, followed by viewing under a high resolution field-emission scanning electron microscope. Two sets of ten particles for each sample were examined. For the spray-dried BSA particles, a decrease in particle porosity (from 50 to 0%) was observed with increasing particle surface corrugation. Spray-dried mannitol, disodium cromoglycate and sodium chloride particles were determined to be 90-100%, 0-10% and 0% porous, respectively. The porosity in the BSA and mannitol particles thus should be considered for the aerodynamic behaviour of these particles. The FIB technology represents a novel approach useful for probing the interior of particles linking to the aerosol properties of the powder. Suitable milling protocols have been developed which can be adapted to study other similar particles.