Resistance interaction phenomena

Of course, condensed phases also exliibit interesting physical properties such as electronic, magnetic, and mechanical phenomena that are not observed in the gas or liquid phase. Conductivity issues are generally not studied in isolated molecular species, but are actively examined in solids. Recent work in solids has focused on dramatic conductivity changes in superconducting solids. Superconducting solids have resistivities that are identically zero below some transition temperature [1, 9, 10]. These systems caimot be characterized by interactions over a few atomic species. Rather, the phenomenon involves a collective mode characterized by a phase representative of the entire solid. 

The majority of food flavors are known to be volatile even at ambient temperatures,The molecular entrapment of flavors reduces their equilibrium vapor pressure via fixation in a molecular cavity. The apolar-apolar interaction between the internal wall of the cyclodextrin and the guest molecule results in remarkable heat resistence of volatiles,Signs of this inclusion phenomenon can be seen in heat stability tests. 

Two-way analysis of variance (and higher classifications) leads to the presence of interactions. If, for example, an additive A is added to a lube oil stock to improve its resistance to oxidation and another additive, B, is added to inhibit corrosion by the stock under load or stress, it is entirely possible that the performance of the lube oil in a standard ball-and-socket wear test will be different from that expected if only one additive has present. In other words, the presence of one additive may adversely or helpfully affect the action of the other additive in modifying the properties of the lube oil. The same phenomenon is clearly evident in a composite rocket propellant where the catalyst effect on burning rate of the propellant drastically depends on the influence of fine oxidizer particles. These are termed antagonistic and synergistic effects, respectively. It is important to consider the presence of such interactions in any treatment of multiply classified data. To do this, the two-way analysis of variance table is set up as shown in Table 1.24. 

Plants have active and passive mechanisms for resistance to most microorganisms. Since chemicals used for weed control interfere with metabolic processes of plants, interactions between herbicides and plant pathogens are to be expected. Interactions commonly, although not always, result in increased disease associated with herbicide use. Several examples of disease enhancement by herbicides were described in the preceding chapter. We describe here a less common phenomenon where certain fungi that colonize plant roots enhance the efficacy of a herbicide. 

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