Future research needs elements

The review is organized as follows. Section 2 defines a systematic framework for fuel cell modeling research, called computational fuel cell dynamics (CFCD), and outlines its four essential elements. Sections 3—5 review work performed in the past decade on PEFCs, DMFCs, and SOFCs, respectively. Future research needs and directions of the three types of fuel cells are pointed out wherever applicable and summarized separately at the end of each section. 

Although a richness of information has been obtained, a number of open questions still remain. For elements which were chemically identified, like Rf or Sg, a more detailed study, both theoretical and experimental, should follow. Elements 109, 110 and 111 are still to be studied experimentally the prerequisites for their successful experimental studies should be similar to those of the lighter transactinides. These include the existence of isotopes long enough for chemical studies, knowledge of their nuclear decay properties, so that they can be positively identified, synthesis reactions with the highest possible cross sections and suitable techniques for their separation. For those elements, predictions of the chemical behaviour are a matter of future research. Especially difficult will be the accurate prediction of adsorption of the heaviest elements on various surfaces, or their precipitation from aqueous solutions by determining electrode potentials. For that, further developments in accurate calculational schemes are needed. More sophisticated methods are needed to treat weak interactions, which are important for physisorption processes. 

In summary, Li-S batteries are of particular interest in the low cost and high energy density EES for the transportation and stationary apphcations. At present, the theoretical capacity of elemental sulfur cannot be fuUy utihzed, and cychng performances (such as coulombic efficiency, capacity retention, cycle hfe etc.) are far away from the practical apphcations. Fundamental research and material breakthroughs are needed in future research. 

This is documented by the discovery of essential functions for the "new trace elements in the past seven years (I) and by the increasing knowledge of marginal or pronoimced deficiencies in humans of such elements as iron (2), zinc (3), chromium (4), and perhaps copper (5) and selenium (6), Although some of these deficiencies occur only in special age and sex groups or under unusual conditions, their existence has aroused public and scientific concern for the exact definition of human trace element needs and for the assessment of trace element nutritional status. These two major challenges for human trace element research cannot be met without proper analytical support. I will attempt to describe the present status of trace element analysis as it relates to nutrition research and to point out some new concepts that might well influence the future direction of trace element analysis. 

Further research into these highlighted problems - and the data subsequently acquired - should provide valuable information to help our understanding of the complex interactions that exist between trace elements in the soil and the health of plants, animals, and humans. Moreover, these new findings should provide decision makers with the information needed to solve national and international problems, and to ensure a sound environment for future generations. 

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