Aggregation simultaneous

We assume that the population density is so small that during a time interval dt, the probability of more than two particles aggregating simultaneously to form a single particle is only of order 0 dt ) while that of two... 

Soap is one example of a broader class of materials known as surface-active agents, or surfactants (qv). Surfactant molecules contain both a hydrophilic or water-liking portion and a separate hydrophobic or water-repelling portion. The hydrophilic portion of a soap molecule is the carboxylate head group and the hydrophobic portion is the aUphatic chain. This class of materials is simultaneously soluble in both aqueous and organic phases or preferential aggregate at air—water interfaces. It is this special chemical stmcture that leads to the abiUty of surfactants to clean dirt and oil from surfaces and produce lather. 

The most recent advance in treating HIV infections has been to simultaneously attack the virus on a second front using a protease inhibitor. Recall from Section 27.10 that proteases are enzymes that catalyze the hydrolysis of proteins at specific points. When HIV uses a cell s DNA to synthesize its own proteins, the initial product is a long polypeptide that contains several different proteins joined together. To be useful, the individual proteins must be separated from the aggregate by protease-catalyzed hydrolysis of peptide bonds. Protease inhibitors prevent this hydrolysis and, in combination with reverse transcriptase inhibitors, slow the reproduction of HIV. Dramatic reductions in the viral load in HIV-infected patients have been achieved with this approach. 

Hence, pseudosimultaneous spectroscopic and flow-cytometric measurements suggest that actin polymerization may be functionally related to aggregation, possibly by reorganization of adhesive molecules on the cell surface. Simultaneous spectroscopic and fluorometric measurements suggest that the signal Ca may be related to oxidant production and degranulation. 

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