ESR spectroscopy as a tool for identifying joining fragments of antique marbles: the example of a pulpit by Donatello and Michelozzo

ESR spectroscopy is one of the physicochemical techniques used to characterize archaeological white marbles and obtain information about their quarries of provenance. This is done by measuring selected spectral features of the Mn(2+) impurity ubiquitously present in marbles and developing a statistical classification rule from the variable vectors measured for a significant number of samples of known provenance (the quarry database). Now we show that the overall variability exhibited by the same spectroscopic features decreases rapidly with the linear dimensions of the sampled block and can be used to distinguish fragments belonging to the same piece of stone from those simply originating from the same quarry. Application of the method to the seven marble panels of the Donatello pulpit in Prato (Tuscany) shows that they have all been cut from the same single block and their different degradation must be ascribed to differential weathering and to the different conservation treatments undergone in the past. The limits and possible drawbacks of the method are also discussed.     

Novikov Conjectures for Arithmetic Groups with Large Actions at Infinity

We construct a new compactification of a noncompact rank one globally symmetric space. The result is a nonmetrizable space which also compactifies the Borel–Serre enlargement X of X, contractible only in the appropriate ech sense, and with the action of any arithmetic subgroup of the isometry group of X on X not being small at infinity. Nevertheless, we show that such a compactification can be used in the approach to Novikov conjectures developed recently by G. Carlsson and E. K. Pedersen. In particular, we study the nontrivial instance of the phenomenon of bounded saturation in the boundary of X and deduce that integral assembly maps split in the case of a torsion-free arithmetic subgroup of a semi-simple algebraic Q-group of real rank one or, in fact, the fundamental group of any pinched hyperbolic manifold. Using a similar construction we also split assembly maps for neat subgroups of Hilbert modular groups.     

Dynamic combinatorial libraries based on hydrogen-bonded molecular boxes

This article describes two different types of dynamic combinatorial libraries of host and guest molecules. The first part of this article describes the encapsulation of alizarin trimer 2a3 by dynamic mixtures of up to twenty different self-assembled molecular receptors together with the amplification and selection of the best binder. Receptors (1a-d)3.(DEB)6 are formed by the self-assembly of six diethyl barbiturate (DEB) and calix[4]arene dimelamine derivatives 1a-d by using hydrogen bonds. The largest amplification factor (2.8) for a host assembly (1a3.(DEB)6) was observed after the addition of 2a to four-component library 1a(n).1b(3-n).(DEB)6 (n=0-3). Addition of 2a to twenty-component library 1a(n).1b(m).1c(o).1d(3-(n+m+o)).(DEB)6 (n, m, o=0-3; (n+m+o)相似文献