• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.6
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• pp.232-237
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• 2016

Cocrystallization of active pharmaceutical ingredients has been widely recognized as a versatile tool to regulate the physical properties of pharmaceutical compounds through designed crystal structures. Grinding or milling has been especially useful to screen the feasibility of cocrystal formation, and the addition of a small amount of liquid is routinely necessary. In the present study, the effect of temperature was studied for the milling cocrystallization of ibuprofen and nicotinamide to establish a liquid-free method. The milling-induced cocrystallization was more effective with liquid nitrogen cooling than at room temperature, which was confirmed by XRD and DSC analyses. This behavior was attributed to the limited molecular mobility below the glass transition temperatures of the cocrystal components, which made it effective to destruct the crystals of raw materials and consequently form the ibuprofen/nicotinamide cocrystal. Further studies would be necessary to establish the utility of the current conclusion to the field of pharmaceutical crystallization.

• Journal of Powder Materials
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• v.18 no.1
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• pp.35-40
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• 2011

LAS-system ceramic powder, spodumene ($Li_2O{\cdot}Al_2O_3{\cdot}4SiO_2$), was successfully synthesized by a chemical solution technique employing PVA(polyvinyl alcohol) as an organic carrier. The PVA content affected the microstructure of porous precursor gels and the crystalline development. The optimum PVA content contributed to homogeneous distribution of metal ions in the precursor gel and it resulted in the synthesis of glass free $\beta$-spodumene powder having a specific surface area of $7.57\;m^2/g$. The agglomerated $\beta$-spodumene powders were also enough soft to grind to fine powders by a simple ball milling process. The microstructures of the densified powder compacts were strongly dependant on the minor phases of spodumene solid solution and amount of liquid phase, which were formed from the inhomogeneous precursors.

• Korean Journal of Food Science and Technology
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• v.51 no.2
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• pp.97-102
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• 2019

Wheat germ, which is rich in nutrients and phytochemicals, is a by-product during the milling process of wheat kernel. In this study, we aimed to increase the amount of bioactive 2,6-dimethoxy-1,4-benzoquinone (2,6-DMBQ) in wheat germ using the cell-wall-degrading enzyme cellulase (Celluclast 1.5L). The amounts of organic acids, free sugars, and 2,6-DMBQ in wheat germ treated with Celluclast 1.5L were evaluated at various reaction times and temperatures. The results of reversed-phase high-performance liquid chromatography of Celluclast 1.5L-treated wheat germ revealed 2,6-DMBQ, four organic acids (tartaric, acetic, lactic, and succinic acids), and three free sugars (sucrose, fructose, and glucose). As reaction time and temperature of the mixture of wheat germ and Celluclast 1.5L increased, the contents of four organic acids, glucose, fructose, and 2,6-DMBQ increased, but that of sucrose decreased. Taken together, these results suggest that Celluclast 1.5L-treated wheat germ containing increased amounts of 2,6-DMBQ serves as a source of functional ingredients in food industry.

• Journal of Powder Materials
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• v.9 no.6
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• pp.394-408
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• 2002

Nanostructured high strength metastable Al-, Mg- and Ti-based alloys containing different amorphous, quasicrystalline and nanocrystalline phases are synthesized by non-equilibrium processing techniques. Such alloys can be prepared by quenching from the melt or by powder metallurgy techniques. This paper focuses on one hand on mechanically alloyed and ball milled powders containing different volume fractions of amorphous or nano-(quasi)crystalline phases, consolidated bulk specimens and, on the other hand. on cast specimens containing different constituent phases with different length-scale. As one example. $Mg_{55}Y_{15}Cu_{30}$- based metallic glass matrix composites are produced by mechanical alloying of elemental powder mixtures containing up to 30 vol.% $Y_2O_3$ particles. The comparison with the particle-free metallic glass reveals that the nanosized second phase oxide particles do not significantly affect the glass-forming ability upon mechanical alloying despite some limited particle dissolution. A supercooled liquid region with an extension of about 50 K can be maintained in the presence of the oxides. The distinct viscosity decrease in the supercooled liquid regime allows to consolidate the powders into bulk samples by uniaxial hot pressing. The $Y_2O_3$ additions increase the mechanical strength of the composites compared to the $Mg_{55}Y_{15}Cu_{30}$ metallic glass. The second example deals with Al-Mn-Ce and Al-Cu-Fe composites with quasicrystalline particles as reinforcements, which are prepared by quenching from the melt and by powder metallurgy. $Al_{98-x}Mn_xCe_2$ (x =5,6,7) melt-spun ribbons containing a major quasicrystalline phase coexisting with an Al-matrix on a nanometer scale are pulverized by ball milling. The powders are consolidated by hot extrusion. Grain growth during consolidation causes the formation of a micrometer-scale microstructure. Mechanical alloying of $Al_{63}Cu_{25}Fe_{12}$ leads to single-phase quasicrystalline powders. which are blended with different volume fractions of pure Al-powder and hot extruded forming $Al_{100-x}$$(Al_{0.63}Cu_{0.25}Fe_{0.12})_x$ (x = 40,50,60,80) micrometer-scale composites. Compression test data reveal a high yield strength of ${\sigma}_y{\geq}$700 MPa and a ductility of ${\varepsilon}_{pl}{\geq}$5% for than the Al-Mn-Ce bulk samples. The strength level of the Al-Cu-Fe alloys is ${\sigma}_y{\leq}$550 MPa significantly lower. By the addition of different amounts of aluminum, the mechanical properties can be tuned to a wide range. Finally, a bulk metallic glass-forming Ti-Cu-Ni-Sn alloy with in situ formed composite microstructure prepared by both centrifugal and injection casting presents more than 6% plastic strain under compressive stress at room temperature. The in situ formed composite contains dendritic hcp Ti solid solution precipitates and a few $Ti_3Sn,\;{\beta}$-(Cu, Sn) grains dispersed in a glassy matrix. The composite micro- structure can avoid the development of the highly localized shear bands typical for the room temperature defor-mation of monolithic glasses. Instead, widely developed shear bands with evident protuberance are observed. resulting in significant yielding and homogeneous plastic deformation over the entire sample.