This project concerns the management of a multimedia database (text and image) of historical papers representing ancient watermarks. The current database contains roughly 3'000 images of such watermarks; the system allows archival and retrieval by means of textual or morphological criteria. During the archival phase, textual description are stored, as well as descriptive primitives extracted together with the watermark itself by image analysis methods. For the retrieval phase, several types of queries are supported; they allow textual search on the basis of the accompanying descriptions, morphological search according to global characteristics, and shape-based search on the basis of the watermark shape. 0-7803-3258-X/96/$5.00 0 1996 IEEE

The electronic publishing, storage and distribution of documents is growing increasingly important and will have profound implications for our economy, culture and society. The multimedia digitalisation of libraries and the distribution of the contents of museums is revolutionising these organisations and will make these resources available to a much wider audience than was previously possible.The main goal of our MEDIA project (Mobile Electronic Documents with Interacting Agents) is the development of a system for the archival, retrieval, and distribution of electronic documents. For this purpose, a mobile agent platform is used to securely distribute these documents. Information is accessed by a search mechanism that allows the retrieval of text and images according to their content.An important feature of the system is a digital watermarking tool which embeds hidden signatures in images. This provides copyright protection and helps to ensure that the image will not be copied and sold and without proper authorisation.The management of the database of documents and images is accomplished by an extensible object relational database management system. In addition, documents and data can be accessed through the World Wide Web network.

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Iron complexes that model the structural and functional properties of the active iron site in rabbit lipoxygenase are described. The ligand sphere of the mononuclear pseudo-octahedral cis-(carboxylato)(hydroxo)iron(III) complex, which is completed by a tetraazamacrocyclic ligand, reproduces the first coordination shell of the active site in the enzyme. In addition, two corresponding iron(II) complexes are presented that differ in the coordination of a water molecule. In their structural and electronic properties, both the (hydroxo)iron(III) and the (aqua)iron(II) complex reflect well the only two essential states found in the enzymatic mechanism of peroxidation of polyunsaturated fatty acids. Furthermore, the ferric complex is shown to undergo hydrogen atom abstraction reactions with O−H and C−H bonds of suitable substrates, and the bond dissociation free energy of the coordinated water ligand of the ferrous complex is determined to be 72.4 kcal•mol −1 . Theoretical investigations of the reactivity support a concerted proton-coupled electron transfer mechanism in close analogy to the initial step in the enzymatic mechanism. The propensity of the (hydroxo)iron(III) complex to undergo H atom abstraction reactions is the basis for its catalytic function in the aerobic peroxidation of 2,4,6-tri(tert-butyl)phenol and its role as a radical initiator in the reaction of dihydroanthracene with oxygen.

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