Achievements to Date

In the relatively few years since the preparation of the previous volume in this series, the explosion of synthetic and clinical experimentation on the semi and totally synthetic antibacterial p-lactam antibiotics has continued, providing a rich body of literature from which to assemble this chapter. The search for utopiasporin, the perfect cephalosporin, continues. The improvements in. spectrum and clinical properties achieved to date, however, are largely incremental and have been achieved at the price of substantially higher costs to the patient. Nonetheless, these newer compounds are truly remarkable when compared with the properties of the fermentation-derived substances from which they have sprung. 

What is needed at this point is a correlation or other means for estimating r] at every point in the reactor. This may be done empirically for example, by running a single tube of what ultimately will be a multitubular reactor. However, some progress has been made in determining r] from first principles. We outline the salient results achieved to date. 

C-C and C-E (E = heteroatom) bond formations are valuable reactions in organic synthesis, thus these reactions have been achieved to date by considerable efforts of a large number of chemists using a precious-metal catalysts (e.g., Ru, Rh, and Pd). Recently, the apphcation range of iron catalysts as an alternative for rare and expensive transition-metal catalysts has been rapidly expanded (for recent selected examples, see [12-20, 90-103]). In these reactions, a Fe-H species might act as a reactive key intermediate but also represent a deactivated species, which is prepared by p-H elimination. 

Every few decades a medical innovation is perfected that profoundly influences the practice of medicine. Widespreadvaccinationagainstcommoninfectious agents and the discovery of antibiotics serve as two such examples. Many scientists now believe that the potential of nucleic-acid- and cell-based technologies rivals even the most significant medical advances achieved to date. 

Although neither Cjryi—H nor Cjikynyi—H bonds have been funchonalized in a catalytic process by iridium pincer complexes, a substanhal mechanishc understanding has been accumulated that may lead to catalyhc reachons in the near future. For this reason-and also due to the fact that some of these achvahon protocols are different from standard processes-a short discussion of the achievements to date is included at this point. 

Keep everyone aware of what has been achieved to date when direction seems to be lost crystallize where the team is at. 

In the future, we need to develop ways to apply novel and more sophisticated surface science techniques, such as the soft X-ray spectroscopies outlined in Chapter 2, to electrified interfaces under realistic conditions. For example, atom-specific probing of the occupied and unoccupied electronic states of electrochemical surface intermediates during the electrocatalytic reactions described in the present chapter has not been achieved to date. Modern synchrotron-based soft X-ray methods will aid these efforts to obtain more insight into the bonding of electrochemical intermediates. 

An appreciable progress in the fundamentals for characterization of branched polymers has been achieved to date by different investigators93-95. Therefore, at present, the physico-chemical behavior of branched polymers in solution as well as in bulk can be elucidated to a great extent on the molecular basis. Kurata et al. proposed a useful, iterative computer method for estimating the degree of branching... 

However, the photocatalytic reactivity of aromatics, especially benzene, is lower than some of the more promising pollutants for this emerging technology. Also, at aromatic concentrations of as little as 10 ppm, photocatalysts may exhibit apparent deactivation. Here, we summarize achievements to date and discuss methods for increasing aromatic reactivity, minimizing photocatalyst deactivation, and periodically regenerating used protocatalysts. 

Although reactive dyes have the potential to provide the best fastness to wet treatments, this potential has only been realized in some small segments. Since 1951, when the first reactive dyes were designed for cotton, many reactive dyes including complete ranges have been offered for leather. However, no major breakthroughs have been achieved to date. 

When irradiation is continued, the hydrogenation rate rises to approximately the same value as observed in the previous irradiation period. This rate is limited by the photon flux, and the turnovers achieved to date are limited by the length of the experiment. In a total reaction time of 28 hours (20 thermal, 8 photochemical) 15 turnovers with respect to moles of rhodium were observed. One turnover per hour was observed with a photon flux of 10 einsteins/minute. 

In this review, I have presented some of the most important members of the azole class. They represent the thousands of compounds synthesized and biologically tested during the past 18 years. The history of the discovery of the azoles and the results achieved to date serve to illustrate the enormous progress made in the past decade in the research and development of organic fungicides. 

No direct observation of RX- by pulse-radiolysis or flash-photolysis techniques has been achieved to date. RX- and especially RC1- are expected to be demonstrable by nanosecond pulse techniques. Unlike I2 or Cfr, the dissociation of RX- will be irreversible, since the organic free radical formed on dissociation will rearrange within < 10-12 sec to a configuration that will not interact with X-. 

There is no doubt that despite the low quantum yields achieved to date for Ndm and Er111 organic materials, polymer optical fibers will be an alternative to silica fibers in the telecommunication windows, mainly in view of their intrinsic advantages cited in section 4, including low cost. A similar conclusion can be drawn for NIR-emitting OLEDs and the availability of fluorinated polymers and [> -diketonates with low vibrations will certainly help boosting... 

A few laboratories worldwide have started research programs aimed at experimentally demonstrating this new X-ray source. Despite several attempts, no successful or convincing experiments have been achieved to date. The advent of well-controlled (in terms of divergence, charge, energy) and stable electron beams shot-to-shot will be required to demonstrate this new scheme as well as to provide useful radiation for application experiments. 

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