Isotropic mixing

Such is the newness of appreciation of near-IR fluorescence techniques that there is a dearth of examples in the literature of implementations of many of the classic fluorescence methods in the IR. Anisotropy is one striking example of this. However, in a comprehensive study of the anisotropy decay of dyes, including oxazine fluorescence at 720 nm, in mixed isotropic solvents Dutt et al.( T7 TS) have investigated the effects of viscosity on molecular rotation. 

Mixed- Isotropic or Anisotropic -variety of shapes or porosities, char wall thickness and/or optical texture. 

Stirring vessels. Upon the examination of different stirring operations it was indeed found that the intensively formulated process parameter P/V represented the pertinent scale-up criterion only if the stirring power has to be dissipated in the volume as evenly as possible (micro-mixing, isotropic turbulence). Examples of this are the dispersion of a gas in a liquid or the dispersion of immiscible liquids s. [22]. 

This simple model accommodates the existence of rod-like structures needed for liquid crystal formation, without recourse to anisotropy of individual molecules. The secretions are biphasic (mixed isotropic/liquid crystalline) over a narrow concentration range implying that they have the thermodynamic characteristics typical of an athermal liquid crystalline solution (Figure 12.10). 

Braunschweiler L and Ernst R R 1983 Coherence transfer by isotropic mixing application to proton correlation spectroscopy J. Magn. Reson. 53 521 -8... 

At low temperature, nonionic surfactants are water-soluble but at high temperatures the surfactant s solubUity in water is extremely smaU. At some intermediate temperature, the hydrophile—Hpophile balance (HLB) temperature (24) or the phase inversion temperature (PIT) (22), a third isotropic Hquid phase (25), appears between the oil and the water (Fig. 11). The emulsification is done at this temperature and the emulsifier is selected in the foUowing manner. Equal amounts of the oil and the aqueous phases with aU the components of the formulation pre-added are mixed with 4% of the emulsifiers to be tested in a series of samples. For the case of an o/w emulsion, the samples are left thermostated at 55°C to separate. The emulsifiers giving separation into three layers are then used for emulsification in order to find which one gives the most stable emulsion. 

When comparable amounts of oil and water are mixed with surfactant a bicontinuous, isotropic phase is formed [6]. This bicontinuous phase, called a microemulsion, can coexist with oil- and water-rich phases [7,1]. The range of order in microemulsions is comparable to the typical length of the structure (domain size). When the strength of the surfactant (a length of the hydrocarbon chain, or a size of the polar head) and/or its concentration are large enough, the microemulsion undergoes a transition to ordered phases. One of them is the lamellar phase with a periodic stack of internal surfaces parallel to each other. In binary water-surfactant mixtures, or in... 

From the selection rules of the 6j coefficients (.89), it follows that the biquadratic terms cannot mix the S = I levels with higher spin states. By contrast, the anisotropic symmetric and antisymmetric terms, whose magnitude is related to that of the isotropic component (89), can give rise to a substantial mixing. However, a detailed quantitative model is needed to verify whether the peculiar magnetic properties of [3Fe-4S] + centers can be explained by this mixing. 

Fig. 14—Comparison between low-speed mixed lubrication and dry contact isotropic waviness. (Profiles are taken along the central lines in x direction at y=0 and in y direction at x=0.) (a) Pressure and film thickness profiles along the x direction at y=0. (b) Pressure and film thickness profiles along the y direction at x=0. (c) The contour plot of film thickness, (d) 3-D plot of pressure distribution.

Fig. 16—Comparison between low-speed mixed lubrication and dry contact an engineering surface with isotropic roughness, (a) Profiles of pressure and film thickness along the x direction at y =0. (b) An enlarged view for the marked zone in Fig. 16(a).

MHz, from 20% w/w CTAB-D20 (41 °C) at observed, consistent with an ordered phase, different positions across the annular gap of a while near the outer wall the single peak of an cylindrical Couette cell and at an apparent isotropic phase is seen. In between, a mixed shear rate of 20 s 1. Near the inner wall, where phase region exists (adapted from Ref. [38]). 

Polysiloxanes in this category typically contain cyclics of -Si(CH3)2-0- siloxane units of various sizes, or such siloxane units mixed with some carbosiloxanes (with additional -CH2- sequences) [163-165]. The cyclic portions can add considerable stiffness, resulting in isotropization temperatures above the polymers decomposition temperatures. 

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