Feasible goals method

Not until 1970 were research efforts directed toward the preparation and testing of cephalosporins with an electronegative heteroatom substituent directly attached to the C-3 position of the cephem ring system. This variation of the molecule became a feasible goal when both chemical and electrochemical methods were developed independently in several laboratories that produce 3-methylenecephams in practical quantities. 

There is no single library creation method that will satisfy the ideal requirements of high-diversity quality, large library size, and ultimately the feasibility of comprehensive screening of the generated library. Evaluation of each case is necessary to determine which library creation method is suitable for the project s goals. 

Often, calibration of natural products and materials is a desirable goal. In these kinds of assays, it is usually not feasible to control the composition of calibration and validation standards. Some well-known examples include the determination of protein, starch, and moisture in whole-wheat kernels and the determination of gasoline octane number by NIR spectroscopy. In cases such as these, sets of randomly selected samples must be obtained and analyzed by reference methods. 

The goal, therefore, is not an ideal catalyst but the optimum, which may be defined by economic feasibility studies concerning not only the catalyst but also the rest of the process. And when the catalytic process is established and the catalyst in question must compete as a replacement, the replacement catalyst s cost and method of manufacture predominate in arriving at the optimum formula. 

Amides being formally hydrated ynamines would constitute cheap starting materials for the latter and many stratagems have been devised to achieve this goal. It must be kept in mind, however, that direct dehydration of amides is not feasible. One indirect approach has already been exemplified, namely the prior conversion of amides into thioamides. Another classical method involves halogen chloride elimination from amide chlorides. These versatile salts have received only scant attention prior to 1960. 

The goal of materials research is really the reverse process, the bottom-up method. In this approach, it is hoped that perfect well-controlled nanoparticles, nanostrucmres, and nanocrystals can be synthesized, which may be compacted into macroscopic nanocrystalline samples, or assembled into superlattice arrays, which may, in mrn, be used in a variety of applications such as nanoelectronic or magnetic devices. Some scientists have even envisioned a time when so-called molecular assemblers will be able to mechanically position individual atoms or molecules, one at a time, in some predefined way (Drexler, 1986). The feasibility of such machines has been hotly debated but, regardless, such systems engineering goals are not really within the scope of this chapter. At present, methods for synthesizing metal and ceramic clusters and nanoparticles fall in one of two broad categories liquid phase techniques or vapor/aerosol methods. 

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