Principal phase

The reactions in the regulated-set cements containing Cjj A3CF2 (note mixed notation) as a principal phase resemble those in ordinary Portiand cements. Initial reaction rates are controlled by ettringite formation. Setting occurs with formation of the monosulfate, along with some transitory lower-limed calcium aluminate hydrates that convert to the monosulfate within a few hours. 

Postlethwaite, L, Edward J.M. and MacFarlane, A.G.J. (1981) Principal gains and principal phases in the analysis of linear mulltivariable feedback systems, IEEE Transactions on Automatic Control, AC-26, pp. 32-46. 

The present study is devoted to the examination of the structure of this boundary layer, which is called mesophase, and which is created between phases in the composite, mainly on the side of the softer phase. This new infinitesimal phase may be assumed as constituting an independent phase, lying between the two principal phases, with its own particular mechanical and physicochemical properties. 

Figures 1 a and 1 b represent the two-phase and the three-phase models respectively in the representative volume element of the composite. In the modified model three concentric spheres were considered with each phase maintaining a constant volume 4). The novel element in this model is the introduction of the third intermediate hybrid phase, lying between the two principal phases.

It is interesting that this cement has been known for over 100 years and yet certain features of its chemistry remain obscure. The exact nature of the matrix is still a matter for conjecture. It is known that the principal phase is amorphous, as a result of the presence of aluminium in the liquid. It is also known that after a lapse of time, crystallites sometimes form on the surface of the cement. A cement gel may be likened to a glass and this process of crystallization could be likened to the devitrification of a glass. Therefore, it is reasonable to suppose that the gel matrix is a zinc aluminophosphate and that entry of aluminium into the zinc phosphate matrix causes disorder and prevents crystallization. It is not so easy to accept the alternative explanation that there are two amorphous phases, one of aluminium phosphate and the other of zinc phosphate. This is because it is difficult to see how aluminium could act in this case to prevent zinc phosphate from crystallizing. 

A major subdivision of processes is possible on the basis of the principal phase in which the reactions take place. This clearly cannot be a clear-cut division since many processes have a number of steps which involve, in turn, the gas phase, the liquid or solution phase, and the solid phase. By and large, however, the principal characteristic step of each process is associated with either the gas phase or solution, and on this basis a significant subdivision can be made. 

A phase can be defined as a domain bounded by a closed surface in which parameters such as composition, temperature, pressure and refractive index are constant but change abruptly at the interface. The principal phases in milk are its serum and fat and the most important interfaces are air/serum and fat/serum. If present, air bubbles, and ice, fat or lactose crystals will also constitute phases. Forces acting on molecules or particles in the bulk of a phase differ from those at an interface since the former are attracted equally in all directions while those at an interface experience a net attraction towards the bulk phase (Figure 11.6). 

The drug designer must consider the susceptibility to, and consequences of, the principal Phase 1 metabolic reactions hydrolysis, reduction and oxidation. Susceptibility to oxidation can be calculated using semi-empirical molecular orbital theory. Ease of oxidation is reflected by the energy of the HOMO, and the probable site of oxidation can be predicted from calculation of the electrophilic superdelocalizability. Likewise, ease of reduction is related to LUMO energy, and probable site to nucleophilic superdelocalizability (Loew and Burt, 1990). 

In liquid-liquid contactors, pressure drop is defined by the light phase. The heavy phase enters at near atmospheric pressure and is accelerated by the rotor to its discharge pressure. The pressure drop of the light phase is a function of phase density difference, rotor speed, rotor diameter, and location of the principal phase interface (24). 

First, consider the fact that there are two principal phase-flow regimes ... 

Clinically, PC-MRA is often used for laminar flow with few pulsations as for example in the cerebral venous sinuses. Many users apply it as a thick slab 2D technique with short acquisition times and primary projective vessel depiction. 3D PC-MRA demands relatively long measurement times for data acquisition and is somewhat sensitive to patient movements. Principally, phase contrast methods additionally enable a quantification of blood flow velocity and the assessment of flow directions. 

Anorthite has an importance far out of proportion to its simple chemistry. First, because of its very low MgO content (hence, high AI/Mg ratio) and the fact that it occurs not just in many CAIs but also in aluminum-rich chondrules, it is a prime analytical target in the search for evidence of extinct A1. Second, like calcic pyroxene, anorthite is one of the principal phases that CAIs share in common with aluminum-rich chondmles. In fact, MacPherson and Huss (2000) showed that the trends defined within CMAS (CaO-Mg0-Al203-Si02) space by silicate-bearing CAI and aluminum-rich chondrule bulk compositions converge on a region intermediate between... 

Haloperidol undergoes extensive metabolism to form a myriad of primary and secondary metabolites (479-486). The principal phase I reactions involve the following oxidative N-dealkylation to initially form 4-fluoro-phenylbenzoylpropionaldehyde (which is rapidly oxidized to the acid) and 4-(4-chlorophenyl)-4-hydroxypiperidine (479,480, 483-485) N-oxidation to form haloperidol-iV-oxide (485) and reversible reduction of the carbonyl group to the alcohol, or reduced haloperidol (481,487). A phase II metabolite, hal-operidol-O-glucuronide, accounts for as much... 

Beside these principal phases, a few supplementary phases are considered, for example, alkaline cleaning, a variant of acid cleaning, or rinsing, a minor phase following acid cleaning. 

The principal phases of an SPE analytical sequence, similar in principle to a chromatographic process where the adsorbent plays a role of the stationary phase and water the role of the mobile phase, are ... 

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