A Multianalytical Approach for the Characterisation of Materials on Selected Artworks by Monogrammist IP.

This paper presents an investigation of wooden artworks from the collection of the National Gallery Prague created by Monogrammist IP-one of the top carvers of the Salzburg-Passau region at the beginning of the 16th century. His wood reliefs were examined to gain a better understanding of the historical techniques used in medieval art workshops. The internal structure of the small relief Visitation was analysed using computed tomography. Tomographic reconstruction made it possible to distinguish wood species, observe the internal structure of the artwork in detail, study the technological procedures and identify earlier repairs, additions and damages. Tomographic investigation proved the use of four types of wood on the relief Visitation, most likely pear, lime, unspecified softwood and other different species used for joining dowels. A combination of non-invasive and micro-destructive analytical techniques was employed for the chemical characterisation of the materials in the surface layers of the artworks. Photomicrographs of the surface were taken to provide material for the initial investigation. Non-invasive material research was conducted using a portable X-ray fluorescence analyser and, in selected cases, an external reflection infrared spectrometer. The detailed analyses on the micro-samples was carried out by optical microscopy, micro-Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray spectrometry and gas chromatography with mass spectrometry. A glaze layer based on protein with earth pigment was identified on the relief Christ the Saviour from Death.

In-situ X-ray Differential Micro-tomography for Investigation of Water-weakening in Quasi-brittle Materials Subjected to Four-point Bending.

Several methods, including X-ray radiography, have been developed for the investigation of the characteristics of water-saturated quasi-brittle materials. Here, the water content is one of the most important factors influencing their strength and fracture properties, in particular, as regards to porous building materials. However, the research concentrated on the three-dimensional fracture propagation characteristics is still significantly limited due to the problems encountered with the instrumentation requirements and the size effect. In this paper, we study the influence of the water content in a natural quasi-brittle material on its mechanical characteristics and fracture development during in-situ four-point bending by employing high-resolution X-ray differential micro-tomography. The cylindrical samples with a chevron notch were loaded using an in-house designed four-point bending loading device with the vertical orientation of the sample. The in-house designed modular micro-CT scanner was used for the visualisation of the specimen's behaviour during the loading experiments. Several tomographic scans were performed throughout the force-displacement diagrams of the samples. The reconstructed 3D images were processed using an in-house developed differential tomography and digital volume correlation algorithms. The apparent reduction in the ultimate strength was observed due to the moisture content. The crack growth process in the water-saturated specimens was identified to be different in comparison with the dry specimens.

Multimodal PSSMA-Functionalized GdF3 : Eu3+ (Tb3+ ) Nanoparticles for Luminescence Imaging, MRI, and X-Ray Computed Tomography.

Biocompatible poly(4-styrenesulfonic acid-co-maleic acid)-stabilized GdF3 : Eu3+ (Tb3+ ) nanoparticles were obtained by a one-step coprecipitation method in ethylene glycol or water. The particles are very small (3 nm), have a narrow size distribution, and were detectable by fluorescence, magnetic resonance, and X-ray contrast imaging. These properties allow multimodal imaging, which has prospective applications in the simultaneous and detailed detection of diseased tissues.