Aggregate mass

For cells that are embedded in macroscopic gel-like structures such as floes, biofilms or other porous media such as soil or sediment aggregates, mass transport to the cells can decrease due to ... 

Figure 1.7 Structure of a ribosome. It is composed of two subunits the large 60S subunit has a mass of 2800 kDa and is composed of three RNA molecules and about 50 protein molecules. The smaller AOS subunit contains one RNA molecule plus around 30 protein molecules and has an aggregate mass of 1400 kDa. ( S is an abbreviabon for a Svedberg, the unit of the sedimentation coefficient. This is measured in an analybcal ultracentrifuge and is related to, but not simply proporbonal to, molecular mass.)...

In severely damaged cells the cell contents were collapsed into an aggregated mass (Fig. 9). Few cellular membranes were evident except for the internal membrane system of the chloro-plasts (Fig. 9G). The crystalline arrays were distributed throughout the aggregated mass (Fig. 9C) and accumulations of electron-dense material occurred generally in association with the periphery of the aggregated mass (Fig. 9, arrows). 

After analyzing some specimens from a pitch lake of Trinidad, Hatchett concluded that a considerable part of the aggregate mass at Trinidad was not pure mineral pitch or asphaltum, but rather a porous stone of the argillaceous genus, much impregnated with bitumen. The specimens he analyzed, however, were not representative of the lake as a whole (20). 

Little is known about archaeal aminoacyl-tRNA synthetases, except that the phenylalanyl tRNA synthetases from the archaea Methanosarcina barkeri and S. acidocaldarius resemble their bacterial and eucaryal counterparts in being tetrameric proteins with an aggregate mass of 270 kDda. The archaeal enzymes, however, do not share antigenic determinants with the bacterial and eucaryal enzymes and are functionally restricted to tRNAs of their own lineage [13,14], Thus, they appear to constitute a third class of tRNA charging enzymes, evolutionarily distinct from those of the other domains. 

A three-dimensional mass fractal dimension. Dm, describes the packing of particles forming an aggregate. Its value varies from 1 to 3. Unlike the Ds, which ascribes a low value to a smooth surface, the higher the value of Dm, the more densely packed is the aggregate. Mass fractal dimension of 3 corresponds to a solid structure. A lower Dm shows a loose and commonly branchier structure of the fractal aggregate (Fig. 3). 

For a structured suspension, obtained by controlled flocculation or the addition of thickeners (such polysaccharides, clays or oxides), the floes sediment at a rate depending on their size and porosity of the aggregated mass. After this... 

To define more clearly the aggregation mechanism, the process may be characterized on the basis of the shape of the aggregate mass (or size) distribution, and the relative variation as a function of time of the weight and number average masses [46], This information well characterized the diffusion- or reaction-limited processes, and these characteristics were determined to be less affected by a concomitant fragmentation process. 

FIG. 1 Evidence for self-similarity of the aggregate mass distribution for the aggregating system (aluminum oxide/polyacrylic acid) according to Eq. 26. 

In this experience, the colloid suspension was introduced into a reactor of volume equal to 50 mL and stirred to ensure homogeneity. At time zero, the polymer solution was injected at constant rate and periodically the corresponding volume of the suspension was collected for a certain time to determine the aggregate mass characteristics and to start fragmentation experiments by immersion of these aggregate samples in the polymer solution of concentration C /30. This procedure allows the surface coverage T(f) to be a linear function of the injection time t due to fast total adsorption of the injected polymer. The variations with time of the average masses N(t) and... 

Bower et al measured the boundary fractal dimension of lactose aggregates in 1,1,2-trichlorotrifluoroethane using serial perimeter dilation and Adler and Hancock s distance transform function [56]. They found that it decreased as shear rate and aggregate mass fractal dimension increased. 

If a system containing a number of aggregates is considered, the aggregate mass distribution is also expected to follow a power-law relationship ... 

Figure AA Dependence of the mean square radius of gyration on the aggregate mass for a collection of reaction-limited cluster aggregation mechanism (RLCA) aggregates. Here, the scaling relationship Rl is verified.

Figure 4.5 Four stages of an off-lattice diffusion-limited CCA process using 10000 elementary spherical particles. In this simulation, the aggregate diffusion coefficient is assumed to be controlled by the aggregate mass using D DqW where m represents the aggregate mass and Do the diffusion coefficient of a single particle. The aggregates generated by this model are self-similar with a fractal dimension of 1.8.

---