Synergism measurement

Synergism is calculated by dividing the measured activity (enzyme combinations) by the expected activity (individual activities, data not shown). Values >1 indicate positive synergism. 

Mutual synergism of binary mixtures containing fine particles can be quantified in terms of the departure of the 0-x2 curve from a linear tie line, which signifies absence of synergism, joining 7 and 2 for the respective components, as shown in Fig. 54. A convenient measure of this departure is the shaded area lying between the -x2-curve and the linear tie line. This can be derived analytically in terms of what will be called the Synergism number Sy, normalized with respect to 07+0, of both the coarse and the fine particles ... 

Figure 54. Measure of synergism for binary particle mixtures. (Kwauk, 1984, 1986.)...

For initiated oxidation, the inhibitory criterion could be defined as the ratio v0/v or (v0/ v — v/v0), where v0 and v are the rates of initiated oxidation in the absence and presence of the fixed concentration of an inhibitor, respectively. Another criterion could be defined as the ratio of the inhibition coefficient of the combined action of a few antioxidants / to the sum of the inhibition coefficients of individual antioxidants when the conditions of oxidation are fixed (fx = IfiXi where f, and x, are the inhibition coefficient and molar fraction of z th antioxidant terminating the chain). It should, however, be noted that synergism during initiated oxidation seldom takes place and is typical of autoxidation, where the main source of radicals is formed hydroperoxide. It is virtually impossible to measure the initial rate in the presence of inhibitors in such experiments. Hence, inhibitory effects of individual inhibitors and their mixtures are usually evaluated from the duration of retardation (induction period), which equals the span of time elapsed from the onset of experiment to the moment of consumption of a certain amount of oxygen or attainment of a certain, well-measurable rate of oxidation. Then three aforementioned cases of autoxidation response to inhibitors can be described by the following inequalities (r is the induction period of a mixture of antioxidants). 

Table II includes supporting data for greater-than-additive inhibition of alfalfa apparent photosynthetic rates induced by SO2+NO2 mixtures. The enhanced effects were most marked at the lower concentrations applied, becoming less pronounced as pollutant levels were raised. At 50 pphm of each gas no synergism was evident. At this SO2 exposure concentration, sulfur dioxide appeared to regulate the observed plant responses. Significant amounts of inhibition resulted from the lowest bipollutant concentrations used (15 pphm of each gas) these concentrations were well below those required for the individual pollutants to measurably suppress apparent photosynthesis rates. At these exposure levels where no tissue necrosis occurred, the plants recovered completely within 2 hr after fumigation. The manner by which this inhibiting interaction occurred is not well understood. This pollutant combination is also known to act in a synergistic fashion to cause visible injury to plants, and further study of this mixture may be warranted.

Non-ideal solution theory is used to calculate the value of a parameter, S, that measures the interaction between two surfactants in mixed monolayer or mixed micelle formation. The value of this parameter, together with the values of relevant properties of the individual, pure surfactants, determines whether synergism will exist in a mixture of two surfactants in aqueous solution. 

POTENTIATOR. A term used in the flavor and food industries to characterize a substance that intensifies the taste of a food product to a far greater extent than does an enhancer. The most important of these are the 5 -nucleotides. They are approved by the FDA. Their effective concentration is measured in parts per billion, whereas that of an enhancer such as MSG is m parts per thousand. The effect is thought to be due to synergism, Potentiators do not add any taste of their own, but intensify7 the taste response to substances already present in the food. 

Due to MoS2/Co9S8 synergism. This invokes an enhanced activity at the phase boundary between MoS2 and Co9S8 for reasons as yet unknown. No quantiative measurements are available to test this hypothesis. 

In the absence of an aqueous phase, the increased >M(III) were attributed to the synergic effect brought about by H2MEHP DAm measured in a mixture... 

In the case of synergism, in which one of the compounds is relatively nontoxic when given alone, the toxicity of the toxic compound can be measured when administered alone or after a relatively large dose of the nontoxic compound. 

Evidence that something more than a proper Alf distribution is needed to create strong acidity first came from the experiments of Beyerlein et al. (7). Using the acid-catalyzed conversion of isobutane as a measure of strong acidity, they found that a dealuminated zeolite prepared by treatment with ammonium hexafluorosilicate (AHF) exhibited much less carbonium ion activity than might be expected, based on the number of Alf atoms. This treatment leaves very little extraframework Al in the zeolite. When the sample was mildly steamed, the activity became considerably greater. The authors concluded that the enhanced acidity was a result of a synergism between the framework Bronsted sites and the Lewis sites associated with extraframework aluminum. 

There is a synergism between adsorption and chromatographic processes which is clearly demonstrated in the supercritical fluid literature. Research in supercritical fluid chromatography can usually be divided into analytical applications and the measurement of physicochemical data. Early analytical separations methodology performed at pressures close to ambient conditions... 

Thus, a positive value of AD shows synergism and a negative value of the same indicates antagonism, and its magnitude is a measure of the extent of these effects. The variation of AD, as a function of different experimental parameters, is the sole basis on which the composition of the extracted species, responsible for synergism, is usually obtained. The value of AD depends on many experimental parameters and, frequently AD approaches D(a+B), when (DA + DB) is negligible relative to D(A+B). 

The organic phase formation constants of adducts between metal chelate and the neutral donor, in the extraction with combinations of acid chelates and neutral extractants, have also been used as a measure of synergism19. When extended to other combinations of extractants such equilibria may not give a complete picture of synergism in view of many other competing equilibria. 

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