Laboratory report preparation components

The following discussion describes how the GLPS can be adapted to the typical field study components, from protocol development to field and laboratory experimental phases, and finally to report preparation and archiving of study data. 

The chemical composition of birch bark tar is dependent on the temperature at which tar is produced. In producing simulated tars in the laboratory for comparison with an adhesive used to repair a Roman jar from Stan wick, Charters et al. (1993) found that tars prepared at 350 °C displayed an increase in triterpenoid hydrocarbons as well as unresolved components presumably resulting from pyrolysis, although the precise nature of these molecules has not been elucidated. Binder et al. (1990) and Charters et al. (1993) also report the presence of allobetul-2-ene [Structure 7.24] in aged birch bark tars. Since this molecule has not been reported in extracts from fresh birch bark, it could be formed during heating to produce the tar (Regert et al., 2003). 

As indicated, a number of laboratories got into the process of purifying the components of nitrogenase, so it is difficult to credit any particular laboratory with first success in the endeavor In 1972,Tsoetol. [22] reported purification of dinitrogenase and dinitrogenase reductase to the highest specific activities reported up to that time. Preparations from different organisms require modification of the techniques. Winter and Burris [23] reported a table of activities of components prepared up to 1976. 

Recently, reports on the preparations and properties of W/O/W (water-in-oil-in-water) emulsions have come from several laboratories (1-21). Although a variety of phase compositions are employed in different studies, the dispersed globules in the W/O/W emulsions can be characterized by a spherical vesicular structure with single or multiple aqueous compartments (inner aqueous phase), which axe separated from the aqueous suspending fluid (outer aqueous phase) by a layer of the oil phase components. 

From the point of view of synthetic effort, preparation of combinatorial mixtures is by far the most economical approach. It can be done with ordinary laboratory equipment and does not take more time than the synthesis of any one of the individual components of the library. This simplicity, however, has its price firstly, the more components a mixture contains the more difficult it becomes to follow the reaction analytically and to determine the actual composition of the reaction product. Secondly, if hits are found in a biological assay, deconvolution is required. In most cases this is done via resynthesis either of the individual components or of subsets of the mixture. If the composition of the initial mixtures was carefully planned it may be possible to identify the active component(s) by simply comparing the composition of the active mixtures with those of the inactive ones. Corresponding procedures have been reported in the literature (e.g., the techniques of indexed [1,2] and orthogonal [3] chemical libraries have been used in solution-phase synthesis). However, the biological effect of a mixture may also be due to a combined action of several weakly active members, with the result that deconvolution does not identify a significantly active compound. Finally, the problem of impurities multiplies with the complexity of the mixtures. 

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