Water from natural systems, comparison

TABLE VI. Comparison of Prepared Waters With Waters From Natural Systems (mg/1)... 

Phospholipases are very versatile enzymes which allow the transformation of inexpensive natural products into highly valuable compounds like specific structurally defined phospholipids, organic monophosphates or diphosphates and DAG with the natural absolute configuration. Of particular synthetic utility is PLD from bacterial sources which is able to effect the phosphoryl transfer in a water-containing biphasic system. PLD shows a wide substrate specificity for both the polar head and the alcohol acceptors as well as for the lipophilic part of the molecule. The enzyme behaves like a generic phosphodiesterase with broad substrate specificity and high transphosphatidylation ability. The molecular basis of this behavior should become clear by inspection of the three-dimensional structure and comparison with other phosphoric acid ester hydrolytic enzymes. The crystal structure of this enzyme has not been elucidated. The potential of the many different PLD from plants which show peculiar substrate specificity should allow one to expand the synthetic utility to the hydrolysis-synthesis of natural and unnatural phosphatidylinositols. 

The data from a representative study of the disappearance of chlorpyrifos from an EPA-14 sediment/water system (p=0.20, fraction sorbed = 0.94) is illustrated in Figure 3. Comparison with Figure 1 shows that once sorptive equilibrium is achieved (t>14,000 minutes) the disappearance rate is first order for both the water and sediment phases. Also, the aqueous disappearance rate constant calculated from the slope of the linear portion of the natural log aqueous concentration versus time plot is 0.5 0.2 x 10 min, which is similar to the values measured in sediment-free EPA-14 supernatant (Table II). A plot summarizing two experiments using EPA-23 sediment is shown in Figure 4. The value of calculated from the... 

Figure 6.4 Comparison of key variables that control coagulation in natural and artificial systems G = mean water velocity gradients (s-1), = particle concentration, and a = collision efficiency. (From Stumm and Morgan, 1996, with permission.)...

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