Growth period

A factor in addition to the RTD and temperature distribution that affects the molecular weight distribution (MWD) is the nature of the chemical reaciion. If the period during which the molecule is growing is short compared with the residence time in the reactor, the MWD in a batch reactor is broader than in a CSTR. This situation holds for many free radical and ionic polymerization processes where the reaction intermediates are very short hved. In cases where the growth period is the same as the residence time in the reactor, the MWD is narrower in batch than in CSTR. Polymerizations that have no termination step—for instance, polycondensations—are of this type. This topic is treated by Denbigh (J. Applied Chem., 1, 227 [1951]). 

Since the recognition in 1936 of the wave nature of neutrons and the subsequent demonstration of the diffraction of neutrons by a crystalline material, the development of neutron diffraction as a useful analytical tool has been inevitable. The initial growth period of this field was slow due to the unavailability of neutron sources (nuclear reactors) and the low neutron flux available at existing reactors. Within the last decade, however, increases in the number and type of neutron sources, increased flux, and improved detection schemes have placed this technique firmly in the mainstream of materials analysis. 

Whereas the use of natural rubber was well established by the start of the twentieth century, the major growth period of the plastics industry has been since 1930. This is not to say that some of the materials now classified as plastics were unknown before this time since the use of the natural plastics may be traced well into antiquity. 

The organism is grown in the broth at about 26°C for a period of 45 hours. During the growth period the broth is stirred and aerated with sterile air in the amount of about 0.5 volume of air per volume of culture broth per minute. 

The culture broth is sterilized by heating it under pressure at about 120°C for about 30 minutes. The broth is cooled and the above inoculant culture is added aseptically. The organism is grown in the broth for 4 days at a temperature of 26°C. During the growth period the broth is stirred and sterile air is blown through the broth at a rate of about 0.5 volume of air per volume of broth per minute. At the end of the growth period the broth shows an antibiotic activity equivalent to about 150 meg of erythromycin per ml of broth. 

The broth culture so obtained is employed as an inoculum (1%). Into each of ten flasks containing 100 ml of sterile nutrient broth is added 1 ml of the inoculum. The flasks are agitated on a rotary shaker for 8 hours at 28°C at 240 strokes per minute. After this growth period, a solution of 25 mg of 16/3-methy(cortisone in 0.5 ml of methanol is aseptically added to each flask which in turn is reshaken and incubated for an additional 24 hours. The final pH is 7.8. 

The oxidation of aluminium at room temperature is reported to conform to an inverse logarithmic equation for growth periods up to 5 years duration. At elevated temperatures, oxidation studies over shorter periods illustrate conformity to parabolic, linear and logarithmic relationships according to time and temperature. These kinetic variations are attributed to different mechanisms of film formation . ... 

If the cells are in the exponential growth period and there is no cell death rate, a 0. The net cell concentration is ... 

Business start-ups - mentors are provided and their usage is often mandatory. The mentors are supposed to help the startup business to whom money has been loaned in order to safeguard that investment and to guide the business through its initial growth period. 

Fig. 1. Elongation rate of stem intemode 12 (A), silks (A), leaf 8 ( ), and nodal roots (O) of maize at various water potentials. Elongation rates are the average per hour for 24 h of growth in a controlled environment chamber. Water potentials were measured in the growing region of each organ in the same plants. Samples were taken immediately after the growth period when the plants had been in the dark for the last 10 h. Each point is from a single plant. Modified from Westgate Boyer (1985a).

Isolation of polysaccharide fractions After a growth period of 8 days the cell biomass was separated by filtration and the spent culture medium was used for the isolation of polysaccharides. The following procedures were examined ... 

Estimate the parameters (pmax, Ks, kd and Y) for each operating temperature. Use the portion of the data where glucose is above the threshold value of 0.1 g/L that corresponds approximately to the exponential growth period of the batch cultures. 

If evapotranspiration of the system exceeds precipitation, it is possible to capture water that is moving vertically through soil. Areas that receive precipitation in the wintertime (the dormant season for deciduous trees) must be modeled to determine if the soil will be sufficiently dry to hold water for the next spring s growth period. 

Initial conditions (1) The temperature distribution in the solid at the beginning of the waiting period is the same as that at the end of the bubble growth period. (2) The temperature of the liquid at the beginning of the waiting period is assumed to be uniform at Tsat. 

To calculate the total ebullition cycle time, the length of the bubble growth period, 0rf, is also needed, which can be estimated by first estimating the bubble diameter at the time of departure and then estimating the time for the bubble to grow to that size, as will be discussed in later sections. 

Figure 2.9 Representation of pressure-temperature relationship that exists during the growth period of a spherical bubble in a superheated liquid of infinite extent. (From Dwyer, 1976. Copyright 1976 by American Nuclear Society, LaGrange Park, IL. Reprinted with permission.)...

In the later stages, bubble growth is controlled more and more by heat transfer to the bubble wall, although for a high-conductivity liquid such as sodium, inertia effects are dominant throughout most of the growth period. 

---