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Prerequisites, general

A general prerequisite for the existence of a stable interface between two phases is that the free energy of formation of the interface be positive were it negative or zero, fluctuations would lead to complete dispersion of one phase in another. As implied, thermodynamics constitutes an important discipline within the general subject. It is one in which surface area joins the usual extensive quantities of mass and volume and in which surface tension and surface composition join the usual intensive quantities of pressure, temperature, and bulk composition. The thermodynamic functions of free energy, enthalpy and entropy can be defined for an interface as well as for a bulk portion of matter. Chapters II and ni are based on a rich history of thermodynamic studies of the liquid interface. The phase behavior of liquid films enters in Chapter IV, and the electrical potential and charge are added as thermodynamic variables in Chapter V. [Pg.1]

Apart from the techniques described in this chapter other methods of organic film fonnation are vacuum deposition or film fonnation by allowing a melt or a solution of the material to spread on the substrate and subsequently to solidify. Vacuum deposition is limited to molecules with a sufficiently high vapour pressure while a prerequisite for the latter is an even spreading of the solution or melt over the substrate, which depends on the nature of the intennolecular forces. This subject is of general relevance to the fonnation of organic films. [Pg.2609]

A complicated analyser system such as that described above can only be maintained if all of the valve-switching events are scheduled in the correct positions in the chromatogram. Mismatch of one of the events will cause (parts of) components to be directed to the wrong columns and thus possible misidentifications. Therefore, accurate determination and maintenance of the cutting windows are essential. This can only be accomplished in a fully automated system with accurate flow and temperature controls. Once these prerequisites are fulfilled, the system will operate unattended and produce results of high quality. The repeatabilities generally achieved are of the order of 1 % rel. [Pg.385]

Prerequisites for liquid-metal embrittlement are that a solid metal should be subjected to tensile plastic strain while wetted by a liquid metal in which it has low solubility. It has been suggested that such embrittlement may be a general phenomenon occurring under appropriate conditions and to varying degrees between all solid-metal/liquid-metal couples and that a... [Pg.1065]

From the above, it will be clear that the fragmentary results obtained so far do not permit one to draw general and detailed conclusions about the transition state. The only conclusion, perhaps trivial, is that coordina-tive unsaturation is a prerequisite for metathesis. [Pg.154]

The resins can be divided into two groups having major structural differences gel and macroreticular . In the case of gel type resins if the beads are totally dry, then the polymeric matrix collapses and the polystyrene chains will be as close as atomic forces allow. Therefore, swelling ability of the reactants is a prerequisite for catalysis by gel resins. Gel resins are characterized by a divinyl benzene content that is generally below 12%. [Pg.127]

The current Good Manufacturing Practice (cGMP) regulations are guidelines that FDA requires a pharmaceutical manufacturer to meet. Compliance with the cGMPs is a prerequisite for the approval of NDAs, INDs, and antibiotic forms. General areas in which... [Pg.412]


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See also in sourсe #XX -- [ Pg.5 ]




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