Growth system, closed

Meniscus-Defined Crystal Growth Systems. In most conventional meniscus-defined growth systems, a seed crystal is dipped into a pool of melt, and the thermal environment is varied so that a crystal grows from the seed as it is pulled slowly out of the pool. Two examples of meniscus-defined growth are shown in Figure 1. The Czochralski (CZ) method (Figure lb) and the closely related liquid-encapsulated Czochralski (LEC) method are batchwise processes in which the crystal is pulled from a crucible with... 

A substantial (twofold) decrease of growth rate in silicon excess has been observed by Anikin et al [36]. Excessive silicon was introduced by a powder SiC source enriched by silicon. It has been noted above that such a source produces a silicon vapour pressure noticeably lower than the saturated value. Most probably the state of the growth system in the experiments of [36] was close to the minimum of the growth rate dependence on p,/p,, see FIGURE 9. The... 

Figure 2. Automated culture of isotopically enriched plants in a closed growth system...

Negatron (P ) decay to stable calcium-40 involves most of the potassium-40 atoms and in fact only 11% of them decay to Ar. In a potassium-bearing system closed to all external influences through geological time, the growth of radiogenic argon-40 and calcium-40 can be... 

No market figures are available for curing agents, but their size and growth are closely related to the use of thermosetting resins and polyurethanes. The overall technical trend is towards systems that are more rapid and safe in use. A specific area of growth is radiation curing, in which the resin system is cured by exposure to a radiation source. This technique is particularly effective for products that can be cured continuously, rather than in batches. 

The nuclear chain reaction can be modeled mathematically by considering the probable fates of a typical fast neutron released in the system. This neutron may make one or more coUisions, which result in scattering or absorption, either in fuel or nonfuel materials. If the neutron is absorbed in fuel and fission occurs, new neutrons are produced. A neutron may also escape from the core in free flight, a process called leakage. The state of the reactor can be defined by the multiplication factor, k, the net number of neutrons produced in one cycle. If k is exactly 1, the reactor is said to be critical if / < 1, it is subcritical if / > 1, it is supercritical. The neutron population and the reactor power depend on the difference between k and 1, ie, bk = k — K closely related quantity is the reactivity, p = bk jk. i the reactivity is negative, the number of neutrons declines with time if p = 0, the number remains constant if p is positive, there is a growth in population. 

A hybridoma can live indefinitely in a growth medium that includes salts, glucose, glutamine, certain amino acids, and bovine serum that provides essential components that have not been identified. Serum is expensive, and its cost largely determines the economic feasibihty of a particular ciilture system. Only recently have substitutes or partial replacements for serum been found. Antibiotics are often included to prevent infection of the culture. The pH, temperature and dissolved oxygen, and carbon dioxide concentration must be closely controlled. The salt determines the osmotic pressure to preserve the integrity of the fragile cell. 

The process of sintering by vapour phase transport is probably important to the growth of single crystals of solids from polycrystalline samples in a closed system, where the vapour species are the transporting gas, which may have the same or different chemical composition from die solid. An example where... 

For crystal growth from the vapor phase, one better chooses the transition probability appropriate to the physical situation. The adsorption occurs ballistically with its rate dependent only on the chemical potential difference Aj.1, while the desorption rate contains all the information of local conformation on the surface [35,48]. As long as the system is close to equilibrium, the specific choice of the transition probability is not of crucial importance. 

Martensitic phase transformations are discussed for the last hundred years without loss of actuality. A concise definition of these structural phase transformations has been given by G.B. Olson stating that martensite is a diffusionless, lattice distortive, shear dominant transformation by nucleation and growth . In this work we present ab initio zero temperature calculations for two model systems, FeaNi and CuZn close in concentration to the martensitic region. Iron-nickel is a typical representative of the ferrous alloys with fee bet transition whereas the copper-zink alloy undergoes a transformation from the open to close packed structure. ... 

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