Pure phases

The special estimates used in BLIPS, which are essentially pure phases of the "solvent components" (98%, with 2% of the other solvent) are chosen to avoid these problems in this iterative procedure. 

The reports were that water condensed from the vapor phase into 10-100-/im quartz or pyrex capillaries had physical properties distinctly different from those of bulk liquid water. Confirmations came from a variety of laboratories around the world (see the August 1971 issue of Journal of Colloid Interface Science), and it was proposed that a new phase of water had been found many called this water polywater rather than the original Deijaguin term, anomalous water. There were confirming theoretical calculations (see Refs. 121, 122) Eventually, however, it was determined that the micro-amoimts of water that could be isolated from small capillaries was always contaminated by salts and other impurities leached from the walls. The nonexistence of anomalous or poly water as a new, pure phase of water was acknowledged in 1974 by Deijaguin and co-workers [123]. There is a mass of fascinating anecdotal history omitted here for lack of space but told very well by Frank [124]. 

Figure Bl.17.5. Examples of CTFs for a typical TEM (spherical aberration = 2.7 mm, 120 keV electron energy). In (a) and (b) the idealistic case of no signal decreasing envelope fimctions [77] are shown, (a) Pure phase contrast object, i.e. no amplitude contrast two different defocus values are shown (Scherzer focus of 120 mn imderfocus (solid curve), 500 mn underfocus (dashed curve)) (b) pure amplitude object (Scherzer focus of 120 mn underfocus) (c) realistic case mcluding envelope fimctions and a mixed weak...

Transfer of material between phases is important in most separation processes in which two phases are involved. When one phase is pure, mass transfer in the pure phase is not involved. For example, when a pure liqmd is being evaporated into a gas, only the gas-phase mass transfer need be calculated. Occasionally, mass transfer in one of the two phases may be neglec ted even though pure components are not involved. This will be the case when the resistance to mass transfer is much larger in one phase than in the other. Understanding the nature and magnitudes of these resistances is one of the keys to performing reliable mass transfer. In this section, mass transfer between gas and liquid phases will be discussed. The principles are easily applied to the other phases. 

Energy Requirements The thermodynamic limit on energy is the ideal energy needed to move water from asahne solution to a pure phase. The theoretical minimum energy is given by ... 

In contrast molecular interaction kinetic studies can explain and predict changes that are brought about by modifying the composition of either or both phases and, thus, could be used to optimize separations from basic retention data. Interaction kinetics can also take into account molecular association, either between components or with themselves, and contained in one or both the phases. Nevertheless, to use volume fraction data to predict retention, values for the distribution coefficients of each solute between the pure phases themselves are required. At this time, the interaction kinetic theory is as useless as thermodynamics for predicting specific distribution coefficients and absolute values for retention. Nevertheless, it does provide a rational basis on which to explain the effect of mixed solvents on solute retention. 

Measurement of the contact angle at a solid-liquid interface is a widely used method for the determination of the surface energy of solid polymers. Fowkes [1] first proposed that the surface energy of a pure phase, y y could be represented by the sum of the contribution from different types of force components, especially the dispersion and the polar components, such that ... 

A chemical reaction can occur only if — AG > 0, i.e. if — AG is positive in addition the value a = is by definition the maximum activity for a condensed component where the pure phase is taken as standard state, thus A/i is always negative. This discussion will be restricted to gases where p 1 taking p = 1 atm (101 325 kN/m ) as the standard state for the gas, X, it is evident that A/ix is always a negative quantity or zero. 

The equilibrium between a compressed gas and a liquid is outside the scope of this review, since such a system has, in general, two mixed phases and not one mixed and one pure phase. This loss of simplicity makes the statistical interpretation of the behavior of such systems very difficult. However, it is probable that liquid mercury does not dissolve appreciable amounts of propane and butane so that these systems may be treated here as equilibria between a pure condensed phase and a gaseous mixture. Jepson, Richardson, and Rowlinson39 have measured the concentration of... 

The preparation of single-phase products is difficult. For the Mo-B system, only Mo is deposited < 1060°C. At 1060-1260°C the deposit composition changes from Mo + M02B through MojB to MojB + MoB. Pure MoB is deposited at 1260-1450°C. Mixtures of MoB and MojB, are obtained above these T. For W metal, deposition proceeds at < 1150°C, after which W + WjB, pure W2B and WiB -f WB are successively deposited with increasing temperature < 1300°C. Pure phases of WB and W2B5 are obtained at 1400 and 1600°C, respectively. 

If the ball contacts the surface of the glass disk without oil, /z = 0, and then the pure phase change of the system can be obtained as follows ... 

The synthesis of quaternary thiospinels, like Ag2FeSn3Sg [5], Ag2MnSn3Sg [6], and Cu2NiSn3Sg [7], has been achieved by reacting metals along with sulfur powder in an evacuated silica tube. Pure phases of these compounds were obtained at 750 °C, 670 °C and 750 °C respectively. 

The peak shapes in 3D spectra can be obtained from the phases of the corresponding signals in the two 2D experiments from which the 3D spectrum is derived. This, if the two 2D spectra have pure phases, e.g., absorption signals, then the 3D cross-peaks will also be in the pure-... 

No new peaks were observed in the mechanical mixtures. The binding energies of all elements were the same in the pure phases and in the mixtures [14]. Figure 1 shows the apparent atomic percentages of molybdenum and cobalt, as given by XPS, on the surface of the sulfided pure phases and mechanical mixtures. In both cases, the experimental results are close to the theoretical values calculated according to Equation 2. 

Figure 2 shows the conversions obtained with the three series studied, as a function of the mechanical mixtures composition, one hour after the beginning of the reaction and at the steady-state. Each series presents a maximum of activity, but at a different composition. SA6 series has a maximum between R , values of 50 and 75, whereas SA12 series has a maximum around = 50, and SA60 series near R , = 75. The dashed lines on the figures represent the sum of the individual contributions of the pure phases, calculated according to Equation 3. A very important synergetic effect is observed in all series, i.e., the activity of the mixtures is... 

Table 1 shows the experimental carbon contents of the used samples, compared to the theoretical values obtained by adding the contributions of the individual pure phases, taking into account their proportions in the mixtures. All mechanical mixtures present experimental carbon contents considerably lower than these calculated values. 

Figure 3 shows the amount of Bronsted sites, as measured by the surface of the characteristic IR peak at 1540 cm after outgassing at 523 K, as a function of the composition of the mechanical mixtures. The dashed lines represent the addition of the contribution of the pure phases, calculated as in Equation 3. An enhancement of the amount of Bronsted sites on the mixtures, when compared to the theoretical values, is observed. This effect is not very clear in SA6 series, but it is more evident in SA12 and SA60 series. The reproducibility of the experiments has been checked the variation between different wafers of the same sample was always inferior to 10%. 

The products obtained from DPM cracking in the present work agree with the results from the literature, mentioned in the Introduction, which indicate that the reaction proceeds via carbocation formation on acidic sites. This implies that the decomposition of DPM does not need the successive intervention of two catalytic sites, like in the "ideal hydrocracking" mechanism. Only acidic sites are sufficient to carry out the reaction. The improved activity of the mixtures when compared to the pure phases must therefore be explained differently. 

Pure Phase Encode Magnetic Resonance Imaging of Concrete Building Materials 285 3.4... 

SPRITE is termed a pure phase encode technique because spatial encoding occurs through the application of variable amplitude magnetic field gradients (which yield spatially varying frequencies) applied for fixed periods of time. Variable frequency with a fixed evolution or encoding time yields a variable signal phase. 

The short signal lifetimes of these nuclei (bulk T2 around a hundred ps and T) around a few ms) [14] require the use of pure phase encode methods. The low concentration of these nuclei coupled with the low absolute sensitivity requires a measurement technique that is rapid enough to permit numerous signal averages. 

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