Non-spherical micron and hand-sized particles and their composites have become essential in select application areas of optics, wear resistance, personnel protection, chemical mechanical polishing, and biomedicine. In...Non-spherical micron and hand-sized particles and their composites have become essential in select application areas of optics, wear resistance, personnel protection, chemical mechanical polishing, and biomedicine. In this paper, the synthesis of composite and ceramic non-spherical particles using stop flow lithography is reported. Precursor suspensions of poly（ethylene glycol） diacrylate, 2-hydroxy- 2-methylpropiophenone and SiO2 or Al2O3 are prepared. The precursor suspension flows through a microfluidic device mounted on an upright microscope and is polymerized in an automated process. A photomask patterned with transparent geometric features, which define the cross-sectional shapes of the particles, masks the UV light to synthesize micron sized particles. Particles with axial dimensions ranging from 35 to 167μm were synthesized. Control of device channel depth and objective lens magnification enables the manipulation of the particle size. Composite particles in triangular, square, pentagonal, hexagonal, and circular cross sections were synthesized. Subsequently, the transformation of the composite particles into the corresponding metal oxide particles was achieved through polymer burn-offand sintering.展开更多
Government crackdowns may put the dairy industry back on the right track,but more action will be necessary to ensure dairy safety Nearly half of China’s dairy enter-p rises will be forced to suspend operations or clo...Government crackdowns may put the dairy industry back on the right track,but more action will be necessary to ensure dairy safety Nearly half of China’s dairy enter-p rises will be forced to suspend operations or close their facilities following a watchdog ins pectiont hat found many dairy producers have been operating below quality safety standards.展开更多
基金primarily supported by the National Science Foundation through the Grant DMR-0611612The US Army through the Institute for Soldier Nanotechnologies,under Contract DAAD-19-02-D-0002 with the US Army Research Office,also provided support
文摘Non-spherical micron and hand-sized particles and their composites have become essential in select application areas of optics, wear resistance, personnel protection, chemical mechanical polishing, and biomedicine. In this paper, the synthesis of composite and ceramic non-spherical particles using stop flow lithography is reported. Precursor suspensions of poly（ethylene glycol） diacrylate, 2-hydroxy- 2-methylpropiophenone and SiO2 or Al2O3 are prepared. The precursor suspension flows through a microfluidic device mounted on an upright microscope and is polymerized in an automated process. A photomask patterned with transparent geometric features, which define the cross-sectional shapes of the particles, masks the UV light to synthesize micron sized particles. Particles with axial dimensions ranging from 35 to 167μm were synthesized. Control of device channel depth and objective lens magnification enables the manipulation of the particle size. Composite particles in triangular, square, pentagonal, hexagonal, and circular cross sections were synthesized. Subsequently, the transformation of the composite particles into the corresponding metal oxide particles was achieved through polymer burn-offand sintering.
文摘Government crackdowns may put the dairy industry back on the right track,but more action will be necessary to ensure dairy safety Nearly half of China’s dairy enter-p rises will be forced to suspend operations or close their facilities following a watchdog ins pectiont hat found many dairy producers have been operating below quality safety standards.
