Accretion

Once nuclei form in a supersaturated solution, they begin to grow by accretion and, as a result, the concentration of the remaining material drops. There is thus a competition for material between the processes of nucleation and of crystal growth. The more rapid the nucleation, the larger the number of nuclei formed before relief of the supersaturation occurs and the smaller the final crystal size. This, qualitatively, is the basis of what is known as von Weimam s law [86] ... 

Chondrite classes are also distinguished by their abundances of both volatile and refractory elements (3). For volatile elements the variation among groups results from incomplete condensation of these elements into soHd grains that accrete to form meteorite parent bodies. Volatile elements such as C,... 

Somatotropin, the P-adrenergic agonists, and the anaboHc steroids are considered metaboHsm modifiers because these compounds alter protein, Hpid, carbohydrate, mineral metaboHsm, or combinations of these and they partition nutrient use toward greater rates of protein deposition, ie, muscle growth, and lesser rates of Hpid accretion. Historical data leading to understanding of the mechanism (s) of action are found in reviews on anaboHc steroids (1), somatotropin (2—4), and the phenethano1 amines (5—7). 

Mechanism of Action. P-Agonists stimulate skeletal muscle growth by accelerating rates of fiber hypertrophy and protein synthesis, but generally do not alter muscle DNA content in parallel with the increases in protein accretion (133—135). This is in contrast to the effects of anaboHc steroids and ST on skeletal muscle growth. Both of the latter stimulate fiber hypertrophy and muscle protein synthesis, but also increase muscle DNA content coincident with increased protein accretion. Whether the P-agonists decrease muscle protein degradation is equivocal. 

The success of the process results from the fact that nowhere inside the furnace is heat extracted from the copper-saturated blast furnace buUion through a soUd surface. The problem of accretion formation (metal buUd-up), which has plagued many other attempts to estabUsh a copper dtossing operation of this type, does not arise. In the cooling launder, lead-rich matte and slag accumulate on the water-cooled plates, but these ate designed so that when they ate lifted from the buUion stream, the dross cracks off and is swept into the furnace via the cooled lead pot. 

C its solubihtyis only 14-15 mg/L. As the temperature increases, so does the solubihty until at 100°C solubihty reaches 30-40 mg/L. This faint solubility at elevated temperatures accounts for the accretion of a primarily CaCO scale in steam boilers. Carbon dioxide exerts a mild solvent action on... 

Figure 2 illustrates a proposed growth process[3] of a polyhedral nanoparticle, along with a nanotube. First, carbon neutrals (C and C2) and ions (C )[16] deposit, and then coagulate with each other to form small clusters on the surface of the cathode. Through an accretion of carbon atoms and coalescence between clusters, clusters grow up to particles with the size fi-... 

In broad outline stars are thought to evolve by the following sequence of events. First, there is self-gravitational accretion from the cooled primordial... 

In fact, the sun is not a first-generation main-sequence star since spectroscopic evidence shows the presence of many heavier elements thought to be formed in other types of stars and subsequently distributed throughout the galaxy for eventual accretion into later generations of main-sequence stars. In the presence of heavier elements, particularly carbon and nitrogen, a catalytic sequence of nuclear reactions aids the fusion of protons to helium (H. A. Bethe... 

Wachstum, w, growth increase accretion, wachstum-fordemd, a. growth-promoting,. hemmend, a. growth-checking, growth-inhibiting. 

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