Means to generate the C-4 carbocations (3) and (4) corresponding to (+)-catechin (1) and (-)-epicatechin (2), respectively, are outlined, and the use of these intermediates for the synthesis of model procyanidins and for the biogenetically patterned synthesis of natural procyanidins is discussed. 13C N.m.r. data for model flavan systems and natural procyanidins are reported and analysed and the information is used to assign the 4R-configuration to four natural procyanidin dimers. The phenomenon of conformational isomerism is demonstrated for the natural procyanidin dimers, and two different forms of restricted rotation about the interflavan bond are proposed. The information is used to clarify many earlier structural anomalies, to predict preferred conformations, and to specify a C(4)-C(8) link for the four principal dimers (B-1-4).The properties of some procyanidin polymers are noted, and structures of opposite helicity are proposed for two of the major types found in nature. Chemistry, University of Sheffield, Sheffield S3 7HFMANY plants, particularly those with a woody habit of treated with acid and may be astringent to the taste.2 growth, contain colourless phenolic substances (pro-The most widely distributed of these proanthocyanidins anthocyanidins) which release anthocyanidins when in nature are the dimers and higher oligomers of the 2 E. Haslam, ' The Flavonoids,' ed.

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Blast-induced traumatic brain injury (TBI) has become a signature wound of recent military activities and is the leading cause of death and long-term disability among U.S. soldiers. The current limited understanding of brain injury mechanisms impedes the development of protection, diagnostic, and treatment strategies. We believe mathematical models of blast wave brain injury biomechanics and neurobiology, complemented with in vitro and in vivo experimental studies, will enable a better understanding of injury mechanisms and accelerate the development of both protective and treatment strategies. The goal of this paper is to review the current state of the art in mathematical and computational modeling of blast-induced TBI, identify research gaps, and recommend future developments. A brief overview of blast wave physics, injury biomechanics, and the neurobiology of brain injury is used as a foundation for a more detailed discussion of multiscale mathematical models of primary biomechanics and secondary injury and repair mechanisms. The paper also presents a discussion of model development strategies, experimental approaches to generate benchmark data for model validation, and potential applications of the model for prevention and protection against blast wave TBI.

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