Synergistic mechanisms between

Yatchigo S, Sasaki M, Kojima F. Studies on polymer stabilizers. Part II a new concept of a synergistic mechanism between phenolic and thiopropionate type antioxidants. Polym Degrad Stab 1992 35 105-13. 

This accounts for the considerable discrepancy between the alkene Z/E ratio found on work-up and the initial oxaphosphetan ais/trans ratio. By approaching the problem from the starting point of the diastereomeric phosphonium salts (19) and (20), deprotonation studies and crossover experiments showed that the retro-Wittig reaction was only detectable with the erythreo isomer (19) via the cis-oxaphosphetan (17). Furthermore, it was shown that under lithium-salt-free conditions, mixtures of (19) and (20) exhibited stereochemical drift because of a synergistic effect (of undefined mechanism) between the oxaphosphetans (17) and (18) during their decomposition to alkenes. 

Kauppila et al. 1992). The synergistic interaction between cocaine and opioid analgesia likely involves noradrenergic mechanisms, supraspinal ju and 5 receptors, and spinal ju receptors (Misra et al. 1987 Sierra et al. 1992). 

Mechanical property studies of the 10% 6F-PAI and PBI blend films further confirmed the existence of synergistic miscibility between the blend component since the tensile modulus and strength of each corresponding file was either equivalent to or exceeded the simple rule of mixtures (Fig. 11). 

An improvement in foam stability was observed as R was increased to >0.15 (Figure 17). This was accompanied by the onset of surface diffusion of a-la in the adsorbed protein layer. This is significantly different compared to our observations with /8-lg, where the onset and increase in surface diffusion was accompanied with a decrease in foam stability. Fluorescence and surface tension measurements confirmed that a-la was still present in the adsorbed layer of the film up to R = 2.5. Thus, the enhancement of foam stability to levels in excess of that observed with a-la alone supports the presence of a synergistic effect between the protein and surfactant in this mixed system (i.e., the combined effect of the two components exceeds the sum of their individual effects). It is important to note that Tween 20 alone does not form a stable foam at concentrations <40 jtM [22], It is possible that a-la, which is a small protein (Mr = 14,800), is capable of stabilizing thin films by a Marangoni type mechanism [2] once a-la/a-la interactions have been broken down by competitive adsorption of Tween 20. 

A synergistic effect between the role of stress and environmental agents such as O3, SO2 and NO2 on degradation of the mechanical properties of Nylon fibers has been observed. This... 

Exact mechanisms may not be completely elucidated, but there is consensus that dissimilarities in localized chemical structures play an important role (Dea, 1989), arguing unavoidable entrapment of one polysaccharide in the gel of the other. Turquois et al. (1992) appeared to support the entrapment hypothesis by suggesting that synergistic gelation between K-car-rageenan and locust bean gum results in network coupling. 

Mechanisms of Interaction. The synergistic phenomenon between hindered phenolics and thiodipropionate esters involves free radical scavenging by the phenolic, peroxide decomposition by the sulfide ester and by the products of disproportionation of oxidized forms of the sulfur compound, and finally, regeneration of the phenolic by the disproportionation products. 

Exposure to the environment (gases and humidity) affects mechanical properties, friction, and wear of polymers. Most of the time, synergistic effects between abrasion, wear and corrosion are created and that amplifies the damage.74,75 Dunn76 has summarized the dominant and synergistic influence of every factor as follows. 

Of course, the Lewis basicities of the PX3 ligands vary considerably, and not entirely predictably with X. This must be taken into consideration because, as with other classes of ligands, the synergistic relationship between <7 donation and n acceptance (regardless of the exact mechanism for the latter) is also a source of ambiguity in understanding this class of ligands. 

Another area where further research may be useful is the synergistic interaction between asbestos and other risk factors for lung cancer, especially smoking. Particularly helpful may be further studies on the mechanism of such interactions, since this could help improve current means of predicting the consequences of exposures to substances such as cigarette smoke. 

---