Physicochemical properties comparability testing

Problems of selection of granular activated carbons in connection with their application for water treatment have been discussed. Analysis of some factors influencing adsorption has been carried out and solution of technolc ic systems has been invented. Physicochemical properties of granular activated carbons of different European firms have been tested. Adsorption capacities of carbons for some model substances of different groups of pollutants have been established. Adsorption in static and dynamic conditions has been compared and correlated. 

As in the case of chemical or pharmaceutical substances, the results from in vitro toxicity testing of NMs are dependent upon many factors, such as the cell types used, exposure time, dosing regimen, and exposure conditions. However, what makes toxicology of NMs so complex as compared to chemical products is the large number of physicochemical properties that are essential to know for proper toxicity assessment. The toxicity mechanisms are multiple and depend strongly on the characteristics of the studied NMs and the conditions of the test. Several aspects may affect the... 

Similar approaches to enhance solubility have been studied in the PAMPA system. For instance, Kansy et al. (2001) explored the use of glycocholic acid to solubilize compounds. As PAMPA is a completely artificial system, it is expected that, compared to cell-based models, higher concentrations of cosolvents can be used. Sugano and coworkers reported that DMSO, ethanol and PEG 400 could be used up to 30% without causing disruptions of the lipid layer (Sugano et al., 2001). An effect of these cosolvents on the physicochemical properties of the test compounds (e.g. impact on pKa) may however lead to an unpredictable effect on drug permeability (Sugano et al., 2001). Currently, DMSO is commonly used as a cosolvent in the PAMPA system at a concentration of 1 to 2%. 

Lewandowicz et al. (1997) conducted experiments to study the effect of microwave processing on the physicochemical properties of cereal starches. They used corn, wheat, and waxy corn at an intermediate moisture content of 30%. Brabender rheological method, light microscopy, x-ray diffractometry (XRD), and differential scanning calorimetry (DSC) methods were used to test different properties of starches, both before and after microwave processing. The experimental results are shown in Figures 3.2 and 3.3. Corn and wheat had pronounced changes in their molecular structure compared to waxy corn. 

The optical spectra of radicals provide important data for testing open-shell methods. Until about 1960 open-shell MO studies were rather rare. An intensive development of open-shell MO theory started in the early sixties and was followed by chemical apphcations and systematic studies in the late sixties. At present it is possible to state that the physicochemical properties of radicals are predicted with an accuracy comparable to that attained for closed-shell molecules. This is important not only from the viewpoint of the electronic spectra, which can hardly be interpreted without MO theory, but also from the viewpoint of the general theory of reactivity, since radicals and excited states offer the means to overcome spin and S5unmetry restrictions in certain chemical reactions. 

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