Growth phases

Since in the initial growth phases of a buoyant plume the plume is nearly symmetrical about its centerline, the buoyancy-induced dispersion in the crosswind (horizontal) direction is assumed to be equal to that in the vertical. Thus, the effective horizontal dispersion is found from... 

Declining growth A growth phase in which the availability of food begins to limit cell growth. 

Rai and Constantinides [14] developed a mathematieal model for the fermentation of the baeterium Pseudomonas ovalis, whieh eonverts the glueose to glueonie aeid. The following equations deseribe the dynamies of the logarithmie growth phase ... 

The large size of nuclear power plant enclosures and the relatively small amounts of readily ignitable fuel in those enclosures make flash combustion unlikely therefore, the concentration is on the fire growth phase. 

Concentration-time curves. Much of Sections 3.1 and 3.2 was devoted to mathematical techniques for describing or simulating concentration as a function of time. Experimental concentration-time curves for reactants, intermediates, and products can be compared with computed curves for reasonable kinetic schemes. Absolute concentrations are most useful, but even instrument responses (such as absorbances) are very helpful. One hopes to identify characteristic features such as the formation and decay of intermediates, approach to an equilibrium state, induction periods, an autocatalytic growth phase, or simple kinetic behavior of certain phases of the reaction. Recall, for example, that for a series first-order reaction scheme, the loss of the initial reactant is simple first-order. Approximations to simple behavior may suggest justifiable mathematical assumptions that can simplify the quantitative description. 

The air-mass thunderstorm is the least severe of all thunderstorms. In its simplest form, an air-mass thunderstorm grows as a single cell when solar radiation heats the surface air in an unstable atmosphere. Its life cycle lasts around 30 minutes. Towering cumulus clouds are formed as in-cloud updrafts push moisture upward. The tower may reach a height about five times the diameter of the cloud base in the growth phase. 

You may for example have suggested that the supply of other nutrients, such as ammonia and O2, may be adjusted to respond to the different needs of growth and penicillin production. You may also have suggested that precursors of specific penicillins, such as P-phenylacetic add, may be added after the growth phase is complete. You may have also considered altering physical parameters such as pH and temperature. 

Batch fermentation is the most widely used method of amino add production. Here the fermentation is a dosed culture system which contains an initial, limited amount of nutrient. After the seed inoculum has been introduced the cells start to grow at the expense of the nutrients that are available. A short adaptation time is usually necessary (lag phase) before cells enter the logarithmic growth phase (exponential phase). Nutrients soon become limited and they enter the stationary phase in which growth has (almost) ceased. In amino add fermentations, production of the amino add normally starts in the early logarithmic phase and continues through the stationary phase. 

Since sucdnoglycan synthesis commences after the growth phase there would be no carbon available for sucdnoglycan formation. 

Once there is an appreciable amount of cells and they are growing very rapidly, the cell number exponentially increases. The optical cell density of a culture can then be easily detected that phase is known as the exponential growth phase. The rate of cell synthesis sharply increases the linear increase is shown in the semi-log graph with a constant slope representing a constant rate of cell population. At this stage carbon sources are utilised and products are formed. Finally, rapid utilisation of substrate and accumulation of products may lead to stationary phase where the cell density remains constant. In this phase, cell may start to die as the cell growth rate balances the death rate. It is well known that the biocatalytic activities of the cell may gradually decrease as they age, and finally autolysis may take place. The dead cells and cell metabolites in the fermentation broth may create... 

The objective of a good process design is to minimise the lag phase period and maximise the length of exponential growth phase. 

Place the flask in a temperature-controlled shaker at 37 °C. The exponential growth phase will last from 2 to 24 hours after inoculation. The exact time and duration depend on the physiological condition of the inoculum. The data in Table 10.1 are plotted and a growth curve will be obtained for an exponentially growing culture. Figure 10.2 shows the typical growth curve obtained for a viable organism. 

Figure 3. Growth phases of short-term cultures. Upon initiation of short-term cultures, growth rapidly increases (Phase 1). A stable growth rate is maintained for a defined number of passages (Phase 2). Finally, most cells undergo a crisis of senescence and ultimately die (Phase 3). In some cases immortal cell lines are established.

Exponential growth occurs after cell metabolisms have adjusted and before a key nutrient becomes limiting or toxic products accumulate. In the exponential growth phase, the total cell mass will increase by a fixed percentage during each time interval, typically doubling every few hours. Ultimately, however, the... 

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