Potential wells composite model

Third, the success of the composite HC-SD model described in Section IX implies the idea that liquid water presents as if a solution of two components. The main one comprises 95% of molecules (librators), which reorient rather freely in a deep potential well and are characterized by a broken H-bond. The second component comprises 5% of molecules, which are H-bonded and perform fast vibration. Molecules of the first group live much longer than those of the second group. Thus a physical sense of the HC model is clarified in Section X as that describing dielectric response of dipoles with broken H-bonds. 

Despite all simplifications the model of particle in the rectangular potential well, extended to include the population of excited le els. describes quite well the dependence of ortho-positronium lifetime on the pore radius. In this model the o-Ps lifetime is ruled entirely by geometrical factors, however, maybe the chemical composition of the medium should be taken into account. The lifetime vs. average radius dependence is particularly steep below 5 nm. and in this range the positron annihilation method can be useful for determination of average pore radii. The specific surface determines the distribution of o-Ps between small voids in the bulk and pores. 

In this way, the near-linear chlorophyll-phosphorus relationship in lakes depends upon the outcome of a large number of interactive processes occurring in each one of the component systems in the model. One of the most intriguing aspects of those components is that the chlorophyll models do not need to take account of the species composition of the phytoplankton in which chlorophyll is a constituent. The development of blooms of potentially toxic cyanobacteria is associated with eutrophication and phosphorus concentration, yet it is not apparent that the yield of cyanobacterial biomass requires any more mass-specific contribution from phosphorus. The explanation for this paradox is not well understood, but it is extremely important to understand that it is a matter of dynamics. The bloom-forming cyanobacteria are among the slowest-growing and most light-sensitive members of the phytoplankton. ... 

The samples used to construct the models should be similar to the production samples also, their spectra should be recorded in the same mode (reflectance, transmission or transflectance) as those for the samples to be subsequently predicted, and include all potential sources of variability. Although such sources are relatively limited - pharmaceutical samples usually have a well-defined qualitative and quantitative composition from raw material to end product, and production processes are solidly established and reproducible - their... 

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