Meta-stability

Meta-phosphorsiure, /. metaphosphoric acid -saure, /. meta acid, metasomatisch, a. metasomatic. meta-stabil, a. metastable, -st dig, a. in the meta position. 

Es konnen auch Hydroxysalze auftreten, die bei alien Konzentra-tionen des neutralen Salzes bzw. seiner Metallionen instabil oder meta-stabil sind. 

The present study consists in examining critically the specific influence of the various organic and inorganic cationic species on the formation and crystallization of ZSM-48 zeolite. Three different reaction systems leading to the formation of ZSM-48 zeolite have been investigated. The first series involved Na+, diamines and Al, the second involved Na+, TMA+ and/or alkylamines and Al, and the last series involved Na+, hexamethonium ions and Al. More particulary, for each organic admixture, we have examined the influence of Na+ and/or Al concentrations on the ZSM-48 (meta)stability and on the nature of the final crystalline product that possibly co-crystallize under these conditions. 

A volt-equivalent diagram for the water-soluble nitrogen species in acidic solution is shown in Figure 6.4. It shows that the nitrate(V) ion is the least stable species, but also indicates the meta-stability of nitrous acid, which is unstable with respect to disproportionation into oxidation states + 5 and zero ... 

It may be evident (it should certainly not be surprising) that the extended MC framework needed to solve the phase-equilibrium problem entails exploration of a path that links the macrostates of the two competing phases, for the desired physical conditions ((i. The generic choices here are distinguished by the way in which the path is routed in relation to the key landmark in the configuration space, namely, the two-phase region which separates the macrostates of the two phases and which confers on them their (at least meta-) stability. Figure 2 depicts four conceptually different possibilities. 

The location and shape of the distribution curve is, of course, dependent on which branch of the hysteresis loop is used to compute the pore size. In spite of the considerable attention given to this problem, in the absence of any detailed knowledge of the pore geometry it is not possible to provide unequivocal general recommendations. In principle, the regions of meta-stability and instability should be established for the liquid/vapour meniscus in the various parts of a given pore structure, but in practice this would be extremely difficult to undertake in any but the simplest types of pore system. 

In this paper we give an overview of the mean-field theory of phase transitions in coupled rotors with particular attention to the issues of reentiance, other quantum anomalies, and meta-stability. We comparatively analyze coupled planar rotors (two-dimensional model) and coupled linear rotors (three-dimensional). We show that the dipolar potential does not exhibit the reentrance anomaly, whereas the quadmpolar one does. The phase transition turns out to be second order in all cases except for the linear rotors in a quadmpolar potential where it is first order. We also investigate the effects of the crystal field in the case of the linear rotor model with quadmpolar potentials the crystal field causes the appearance of critical points which separate lines of the phase diagram where the transition is first order from regions where there is no... 

Change from the yellow to the red form of mercuric iodide at the ordinary temperature is retarded by the presence of mercuric chloride or bromide. Moreover, if mercuric iodide is heated to various temperatures above the melting-point, and then kept at the ordinary temperature, the velocity of change from yellow to red is all the greater the higher the temperature of heating. It would appear that meta- stability is frequently if not always increased by the presence of impurities. ... 

A recently measured disjoining-pressure isotherm of an isolated lamella is shown in Figure 8 for the surfactant sodium dodecyl sulfate (SDS) at 10-3 kmol/m3 in aqueous 0.01 kmol/m3 sodium chloride brine (65). A solid line connects the data points for three independent experimental runs, shown by various symbols. The negative, attractive portion of the isotherm between thicknesses of about 4 and 5 nm is not sketched because equilibrium measurements are not possible there. The measured isotherm indeed obeys the classic S-shape. Film meta-stability demands that the slope of the isotherm be negative (2<5, 72). For positive slopes, even the slightest, infinitesimal disturbance ruptures the film. Thus, the lamella in Figure 8 can exist only along the two repulsive branches near 4 nm and above 7 nm. The thicker branch or common black film arises from electrostatic overlap forces, and the inner branch or Newton black... 

It is now generally recognized that surfactants are indeed crucial, not only in conferring (meta)stability to the emulsion or foam, but also in controlling the rate-dependent rheology of the film surfaces and that of the system as a whole. 

The Meta-Stability of LiaO-Containing Celsian at Temperatures above 1590°C... 

The large number of components (sometimes > 50 different components) and the underlying meta-stabile emulsion system are obvious reasons for incompatibility (as described above) and instability. The occurrence of incompatibihty and instability is often invisible. Physico-chemical reactions with negative effects on the stability are [58] ... 

FeO has three chemical characteristics, i.e., oxidative, non-stoichiometry and meta-stability. They must be taken seriously during the manufacture, reduction and application of Fei xO based ammonia synthesis catalyst. As shown in the researches on iron catalyst during the past century, the iron oxides precursor of the catalysts is Fe304 all along, so it has been studied intensively, while that of FeO is not. Hence, here is a detailed introduction to FeO. 

Tol R, Mathot V, Groeninckx G. Confined crystallization phenomena in immiscible polymer blends with dispersed micro- and nanometer sized PA6 droplets part 4 polymorphous structure and (meta)-stability of PA6 crystals formed in different temperature regions. Polymer 2005 46(9) 2966—77. 

Figure 6.9 shows the disjoining pressure isotherms IT(h ,) at 22 °C for emulsion films from 2 x 10 moldm INUTEC SPl +2 x 10 moldm NaCl aqueous solution [8j. Two independent experiments are shown, presented with different symbols. The agreement between them is not the best one. This can be attributed to the meta-stability of the films. Initially, there is a gradual decrease of the film thickness with increasing pressure, after which there is a jump (marked with arrows in the figure) toward the Newton black film (NBF) formation. This jump is... 

---