Granulometric measurements

The conductometric analyses were carried out in correlation with the granulometric measurements, to determine the release of the encapsulated molecules. The study was carried out for different multiple emulsions prepared with the same lipophilic and hydrophilic surfactants, but with different dispersed mass fractions (20%, 30%, 40%) and thickened by the same hydrophilic polymer at various concentrations (0.5%, 1%, 2%). The release from an unthickened and very concentrated multiple emulsion (80%) was also measured. Figure 8.7 shows the evolution of the release rate as a function of the capillary number Ca, in order to take into account not only the shear rate but also the initial diameter and the viscosity values. 

To test the reliability of the previous method, the authors compared it to an independent measurement of oj. They thus propose an extended version of the previous mean-fleld model, valid at any stage of the coalescence regime, even in presence of broad droplet size distributions. It is obtained by considering that the variation of the total number of coalescence events is proportional to the total surface area per unit volume developed by the droplets of different sizes. The total number of drops and total surface are replaced by summations over all the granulometric size intervals ... 

X) P. Aubertein, MP 37, 139-52(1955) (Particle size measurements of expls) (Granulometric)... 

Fig. 7 Granulometric analyses of griseofulvin loaded particles of PMHS-CD(40) drawn from small angle light scattering measurements performed at different loading stoichiometries (griseofulvin P-cyclodextrin). O 0 1 (blank particles) B 2 1 5 1 pure griseofulvin...

Separation analysis at the outlet of the detector must respect three major conditions. The first is the cell integrity (i.e., the diagnosis of the particle). This can be operated on line, by means of classical photometric devices operated in the light-scattering mode (opacimetry) at 254 nm. Off-line methods, after fraction collection, are possible and recommended, by microscopy and granulometric analysis (Coulter counting). The second objective is to analyze cell viability. Off-line methods after fraction collection are equally possible. The blue trypan exclusion test, motility measurements, or specific enzymatic activities (esterase) can be performed on an aliquot of the collected fraction. 

Despite their marked difference in size (as confirmed by optical microscopy examination), no significant difference in the in vitro dissolution profiles corresponding to the three SDDP fractions could be found The bulk and the sieved fractions of SDDP yield similar specific surface area values as determined by adsorption of Krypton (BET method). This is further confirmed by MIP measurements for which the calculated specific surface areas and total intrusion volumes were found to be equivalent. As also shown by SEM, the corresponding MIP curves demonstrate the existence, whatever the sieved SDDP fraction studied, of open intraparticular pores with a mean access diameter (of about 0 6 tim) which is sufficiently large for water molecules to penetrate into them. Hence, one can understand the equivalence of dissolution rates obtained on the three granulometric fractions. 

This concept has already been defined for cell sorting. " To precisely know the physical characteristics of cell populations, let us imagine a simple bidimensional one where cells are spherical and rigid, and show independent size and density distribution. According to the Steric Hyperlayer mode, with some subpopulations, coelution is possible, generating a need for size or mass detectors. Therefore granulometric or mass measurements appearing at the outlet (online/off-hne) are essential in terms of separation developments. 

As the granulometric composition of the clinker is not always known in advance, optimization of the internal fittings may be possible only when the plant is actually in service. For this purpose it is advantageous to measure the temperature in the interior of the cooling tubes by means of thermocouples. Typical temperature distributions measured in this way, for different operating conditions of the kiln, are represented in Fig. 51. 

Automatic fineness measuring instruments have hitherto also found only limited application. The determination of fineness, optimum granulometric composition (particle size distribution) and bulk density (of clinker) by suitable automatic means offers scope for future development of Instrument technology. 

Therefore, although the Coulter Counter method allows an accurate evaluation of particle volume diameter in inert media as checked by mass balance evaluation, in some cases it is not suitable to measure particle swelling. In these cases, the Coulter Counter method needs to be integrated with other granulometric techniques. 

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