Basic principle membrane characterization

The structure and function of enzymes is determined by both the amino acid sequence and the surrounding solvent. The overall stability of proteins is characterized by a subtle balance of into- and inter-molecular interactions. The basic principle of the structure (and of the stability) of the proteins is related to the nature of its normal enviromnent for (water) soluble globular proteins this is the minimization of the hydrophobic surface area, whereas the contrary is the case for membrane proteins (Jaenicke, 1991). 

Thermoporometry. Thermoporometry is the calorimetric study of the liquid-solid transformation of a capillary condensate that saturates a porous material such as a membrane. The basic principle involved is the freezing (or melting) point depression as a result of the strong curvature of the liquid-solid interface present in small pores. The thermodynamic basis of this phenomenon has been described by Brun et al. [1973] who introduced thermoporometry as a new pore structure analysis technique. It is capable of characterizing the pore size and shape. Unlike many other methods, this technique gives the actual size of the cavities instead of the size of the openings [Eyraud. 1984]. 

M. Mulder, Characterization of membranes, in M. Mulder (Ed.), Basic Principles of Membrane Technology. Kluwer Academic Publishers, The Netherlands, 1991, pp. HOIST. 

Basic principles of hydrogen sorption in, and permeation through, palladium-based metallic membranes are then presented in Sections 18.3 and 18.4. Membrane characterization and performance are discussed in Section 18.5, and some applications are presented in Section 18.6. Finally, advantages and limitations of existing technologies are discussed in Section 18.7, and some prospective issues are considered. 

Conventional non-aqueous pH titrations are useful in detecting and determining acidic and basic impurities. On the other hand, the ion-prove method proposed by Coetzee et al. [9] is convenient in characterizing trace amounts of reactive impurities. The principle of the method was described in Section 6.3.5. In Fig. 10.4, the method is applied to reactive impurities in commercial acetonitrile products. The prove-ion and the ISE were Cd2+ and a Cd2+-selective electrode (CdS-Ag2S solid membrane), respectively. The solid line TR is the theoretical relation expected when the ISE responds to Cd2+ in the Nernstian way. The total concentrations of impurities, which were reactive with Cd2+, were estimated to be 4x10 5 M, 8xlO-6M,... 

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