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Longitudinal and transverse 1 H nuclear magnetic resonance relaxivities of Ln(III)-DOTA complexes (with Ln = Gd, Tb, Dy, Er; DOTA = 1,4,7,10-tetraazacyclododecane-N,N ′ ,N ′′ ,N ′′′ -tetraacetic acid) and Mn(II) aqueous solutions were measured in a wide range of frequencies, 10 kHz to 700 MHz. The experimental data were interpreted by means of models derived from the Solomon-Bloembergen-Morgan theory. The data analysis was performed assuming the orbital angular momentum L = 0 for Gd-DOTA and the aqua ion [Mn(H 2 O) 6 ] 2+ and L ≠ 0 for Dy-, Tb-, and Er-DOTA. A refined estimation of the zero-field-splitting barrier Δ and of the modulation correlation time τv was obtained for [Mn(H 2 O) 6 ] 2+ by extending the fitting of nuclear magnetic relaxation dispersion profiles to the low-field regime. The Gd-DOTA fitting parameters resulted in good agreement with the literature, and the fit of transverse relaxivity data confirmed the negligibility of the scalar interaction in the nuclear relaxation mechanism. Larger transverse relaxivities of Dy-DOTA and Tb-DOTA (∼10 mM −1 s −1 ) with respect to Er-DOTA (∼1 mM −1 s −1 ) were observed at 16 T. Such higher values are suggested to be due to a shorter residence time τm that is possibly linked to the fluctuations of the hyperfine interaction and the different shape of the magnetic anisotropy. The possible employment of Dy-DOTA, Tb-DOTA, and Er-DOTA as negative magnetic resonance imaging contrast agents for high-field applications was envisaged by collecting spin-echo images at 7 T. Particularly in Dy-and Tb-derivatives, the transverse relaxivity at 16 T is of the order of the Gd-one at 1.5 T.

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The introduction of Object Oriented Technologies in test centered processes has emphasized the importance of finding new methods for software verification. Testing metrics and practices, developed for structured programs, have to be adapted in order to address the prerogatives of object oriented programming. In this work, we introduce a new approach to structural coverage evaluation in the testing of OO software. Data flow paradigm is adopted and reinterpreted through the definition of a new type of structure, used to record defuse information for test critical class member variables. In the final part of this paper, we present a testing tool that employs this structure for code based coverage analysis of Java and C ++ programs.