Organic hosts, description

There is no reason why the same principle cannot be applied for light-emitting polymers as host materials to pave a way to high-efficiency solution-processible LEDs. In fact, polymer-based electrophosphorescent LEDs (PPLEDs) based on polymer fluorescent hosts and lanthanide organic complexes have been reported only a year after the phosphorescent OLED was reported [8]. In spite of a relatively limited research activity in PPLEDs, as compared with phosphorescent OLEDs, it is hoped that 100% internal quantum efficiency can also be achieved for polymer LEDs. In this chapter, we will give a brief description of the photophysics beyond the operation of electrophosphorescent devices, followed by the examples of the materials, devices, and processes, experimentally studied in the field till the beginning of 2005. 

Domestic animals have been incredibly useful for discovering novel approaches to combat major disease problems in humans for centuries. Without question, the most notorious infectious disease of all time with a prominent skin lesion was smallpox. Descriptions by Barron (1) remind us of the severity of the skin disease, even though the viral infection involved many other organs. Jenner s controversial work, first published in 1798, based on interspecies transmission of cowpox or, more likely, horsepox, from its natural host to human caretakers who subsequently were immune to smallpox infection lead to the development of vaccines (derived from the Latin word vaccinus, which means relating to a cow)... 

SFB 624 in Bonn proposed a definition for template-assisted reactions [265] which states that a template steers a reaction through spatial pre-organization of the reactants via a suitably defined pattern of non-covalent, covalent, or coordinative-reversible bonds. It acts as an entropic sink such that thermochemical criteria can be used to characterize the template-mediated process. Template-mediated reactions may revolve several times but high turn over numbers are not necessarily required. Also, the template does not necessarily need to be recovered once the reaction took place. In this work, we elaborate on this non-formal description, which aims to embrace as many chemical processes involving templates and host-guest interactions as possible. Our aim is to arrive at a more formal basis utilizing well-established thermochemical concepts. The classical thermochemical approach of physical chemistry to chemical reactions may provide an option to define transferable concepts for the plethora of template-assisted processes. 

There are some molecular biologists and biochemists who believe that a total description of the physics and chemistry of the cell would readily extrapolate to a total description of the organism. For example, the entire nucleotide sequence of at least one simple virus is now known. But does such a specification say all there is to say about the properties of the virus Or are there other things to say which, as I believe, can only be specified in terms of the history of the virus as an organism, its relationship to its environment and to its host or potential host cells. 

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