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Abstract--Structural Fe 3+ in kaolinites and dickites covering a broad range of disorder was investigated using electron paramagnetic resonance (EPR) spectroscopy at both the X and Q-band frequencies. A procedure based on a numerical diagonalization of the spin Hamiltonian was used to accurately determine the second and fourth-order fine-structure parameters. A least-squares fitting method was also developed to model the EPR spectra of Fe 3+ ions in disordered local environments, including multimodal site-tosite distributions. Satisfactory fits between calculated and observed X and Q-band spectra were obtained regardless of the stacking order of the samples.In well-ordered kaolinite, Fe 3+ ions are equally substituted in sites of axial symmetry (Fe(ii)sites, namely Fe(m a and Fe(mb) which were determined to be the two non-equivalent All and A12 sites of the kaolinite structure. In dickite, Fe 3+ ions were also found to be equally substituted for AP + in the two non-equivalent A1 sites of the dickite structure. In poorly ordered kaolinites, the distribution of the fine-structure parameters indicates that Fe 3+ ions are distributed between Fe(,> sites and other sites with the symmetry of the dickite sites.Hence, when stacking disorder prevails over local perturbations of the structure, the near isotropic resonance owing to Fe 3+ ions in rhombically distorted sites (Fe(i) sites) is a diagnostic feature for the occurrence of C-layers in the kaolinite structure, where C refers to a specific distribution of vacant octahedral sites in successive layers.

Abstract--A new appraisal of radiation-induced defects (RID) in natural kaolinite, i.e., positive trapped holes on oxygen atoms, has been undertaken using Q-band EPR spectra, recorded at 93 K, of irradiated annealed and oriented kaolinite samples originating from various environments. Three different centers were identified. Two of the centers, A-and A'-centers, are trapped holes on oxygen from Si-O bonds. They have a distinct signature and orthogonal orientation, i.e., perpendicular and parallel to the (ab) plane, respectively. The third center, the B-center, is a hole trapped on the oxygen bonding A1 in adjacent octahedral positions (Alv~-O--Alw bridge). This confirmed some previous assignments from the literature, some others are no longer considered as valid.A least squares fitting procedure is proposed to assess the RID concentration in any kaolinite. It allows a quantitative approach of the thermal stability of RID. Isochronal annealing shows that the thermal stability of the centers decreases in the order A, A', B over the temperature range 0-450~ (1) B-center is completely annealed above 300~ (2) A'-center can be annealed by heating at 400~ for more than two hours; (3) A-center is stable up to 450~ The activation energy and the magnitude of the mean halflife for A-center is evaluated through isothermal annealing at 350, 375 and 400*(2, with Ea = 2.0 eV + 0.2, and tv, > l0 ~2 years at 300 K. The stability of A-center seems to decrease with increasing crystalline disorder. Nevertheless, it is high enough for radiation dosimetry using kaolinites from any environment on the Earth's surface.

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In the past, research on agent-oriented software engineering had been widely lacking touch with the world of industrial software development. Recently, a cooperation has been established between the Foundation of Intelligent Physical Agents (FIPA) and the Object Management Group (OMG) aiming to increase acceptance of agent technology in industry by relating to de facto standards (object-oriented software development) and supporting the development environment throughout the full system lifecycle.As a first result of this cooperation, we proposed agent UML [Bauer, 1999], an extension of the Unified Modeling language (UML), a de facto standard for object-oriented analysis and design. In this paper, we describe the heart of agent UML, i.e., mechanisms to model protocols for multiagent interaction. Particular UML extensions described in this paper include protocol diagrams, agent roles, multithreaded lifelines, extended UML message semantics, nested and interleaved protocols, and protocol templates.