Challenges in Characterizing Small Particles Exploring Particles from the Nano- to Microscale: A Workshop Summary (2012) / Chapter Skim
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4 Analyzing Nanoparticles in Complex Mixtures
4 Analyzing Nanoparticles in Complex Mixtures
Pages 37-46
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From page 37... ...
Researchers drug formulators are using small particle delivery vehicles lack a quantitative understanding of how microstructure to increase the solubility and uptake of these molecules. Dry develops during processing of complex, multiphase delivery powder aerosols based on relatively large lactose particles forms.
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From page 38... ...
shaped rather than spherical together dominate over gravity and inertia of the particle, resulting in particles that are cohesive, flow poorly, and make Models for Engineering Design complex structures with different levels of aggregation at different length scales." Creating an engineering design requires understanding at Fine powders behave very differently because they many different levels, including of the physics and accompadon't fluidize properly. Litster demonstrated this fact with nying models at different length scales.
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nofusion approach to distribute a silica nanoparticle coating The researchers question whether they can predict ribbon onto API particles and measured the bulk flowability of the density on the basis of particle properties and process condi
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Now, the researchers want to be able to predict how the bulk properties of the ribbon PARTICLES IN THE ENVIRONMENT would be altered by changes in the properties of the original Pedro Alvarez of Rice University said there is a general mixture resulting from, for example, a change in the surface properties of the API. consensus in the environmental engineering community that To explore this idea, the researchers have created a multi- engineered nanoparticles are being used and introduced into particle finite element model that represents a ribbon under commercial products at a rate that is much faster than the stress.
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From page 41... ...
. FIGURE 4-3 Processes that can possibly transform manufactured nanoparticles or modify their surfaces and aggregation states in the environment.
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From page 42... ...
Particle coating can also influence nanomaterial toxicity, Alvarez noted that in March 2009 Rice University held explained Alvarez. His group has shown, for example, that an international workshop on the eco-responsible design and iron nanoparticles coated with polyaspartate do not stick disposal of engineered nanomaterials at which about 50 envito bacteria, eliminating toxicity.
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From page 43... ...
Vicki Grassian of the University of Iowa focused her Although a great deal of research has been conducted on remarks on transformations and surface chemistry of mineral particle surface chemistry , she said little is known about dust, which makes up a large fraction of the aerosol mass. what happens in the environment that lies between the two Mineral dust particles measure from about 0.1 microns (or extremes of dry and wet, a domain in which surface-absorbed 100 nanometers)
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From page 44... ...
example, field measurements in Israel and China have shown Natural particles are more complex not only chemically, that calcium carbonate particles react with sulfur dioxide in but also morphologically. They are not all spheres, which will the environment and that sulfite forms in an intermediate step impact remote sensing data from which aerosol concentra FIGURE 4-5 Calcium carbonate particles react with nitric acid in the presence of water vapor.
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From page 45... ...
Laboratory natural dust particles influences optical and chemical behav- studies can provide insights into these transformations, ior in the atmosphere. but the complexity of real atmospheric dusts means that Particle size is also heterogeneous in natural dusts, and the the insights may not reflect what really happens in the behaviors of particles in the atmosphere vary with their size.
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