Particle formation following expansion

The physical picture of a smoke plume can be developed by considering first a puff of smoke emitted as a point somce. The puff is made up of a gas or small particles which follow the direction of the wind with the speed of the wind. Small eddies caitse dilution and expansion of the puff about the centerline of its path by pitmping fresh air into the puff. Large eddies buffet the puff about and transport it downwind. Linking together an infinity of puffs results-in the formation of continnons release from a point. 

The following mechanisms in corrosion behavior have been affected by implantation and have been reviewed (119) (/) expansion of the passive range of potential, (2) enhancement of resistance to localized breakdown of passive film, (J) formation of amorphous surface alloy to eliminate grain boundaries and stabilize an amorphous passive film, (4) shift open circuit (corrosion) potential into passive range of potential, (5) reduce/eliminate attack at second-phase particles, and (6) inhibit cathodic kinetics. 

Reality is often quite different. When a supercritical fluid mixture expands into pressures as high as ambient conditions, the resultant expansion plume can be a complex mixture it is a high velocity gas stream that entrains precipitated particles of extracted materials and often frozen carbon dioxide. Much adjustment needs to take place in the collection zone in order to achieve something close to 100 % recoveries of solutes with concentration ranges from parts per billion (PCBs) up to 50 % (total fat in a chocolate candy). Besides the flow dynamics of the expansion, several physicochemical parameters cause the deviation from the initial simple model. They include, but are not limited to, volatility of the solute, degree of co-precipitation of solid carbon dioxide (followed almost immediately with uncontrolled subhmation of the solid), aerosol formation, surface tension, occlusion in solid carbon dioxide, rebound from impinging surface, and many other interacting phenomena. 

Two models have been proposed for CM assembly [20]. In the first model, the assembly of VLDLs and CM occurs by two independent pathways. The second model is based on the concept of core expansion that generates lipoproteins of various sizes. This model proposes the initial formation of small lipoprotein particles containing apo B48 and phospholipids, followed by release of these particles from the ER membrane, and subsequent addition of lipids to form lipoproteins of different sizes depending upon the extent to which expansion of the core of the small particle with TG occurs. Small primordial lipoproteins have been detected in enterocytes and recent studies support the second model. 

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