The PUMA beamline, created for the heritage community and accessible by all fields of science, welcomed its first users in 2019. Its optical layout uses a horizontal focusing mirror to prefocus the light emitted from the wiggler source for the experimental endstation. It provides a 5 mu m x 7 mu m microbeam for XRF, XAS, XRD and XEOL analysis or a wide 20 x 5 mm full field when the beam is defocused, and the KB mirrors are retracted. An extremely stable fixed-exit Si(111) monochromator is used to select the wavelength. Many experiments have been performed at PUMA, particularly in archaeology, paleontology, conservation, art history and in identifying safer conditions of irradiation for precious heritage samples. XRF analysis has been used, for example, to show the effects of the interaction of Palaeolithic ivory with soil; to identify the elemental composition of mineralized textiles and to reveal hidden morphologies of fossils.

The present study evaluated the repercussions of magnetopriming on the root system architecture of soybean plants subjected to arsenic toxicity using synchrotron radiation source based micro-computed tomography (SR-mu CT). This will be used evey where as abbreviation for the technique for three-dimensional imaging. Seeds of soybean were exposed to the static magnetic field (SMF) of strength (200 mT) for 1h prior to sowing. Magnetoprimed and non-primed seeds were grown for 1 month in a soil-sand mixture containing four different levels of sodium arsenate (0, 5, 10, and 50 mg As kg-1 soil). The results showed that arsenic adversely affects the root growth in non-primed plants by reducing their root length, root biomass, root hair, size and number of root nodules, where the damaging effect of As was observed maximum at higher concentrations (10 and 50 mg As kg-1 soil). However, a significant improvement in root morphology was detected in magnetoprimed plants where SMF pretreatment enhanced the root length, root biomass, pore diameter of cortical cells, root hair formation, lateral roots branching, and size of root nodules and girth of primary roots. Qualitative analysis of x-ray micro-CT images showed that arsenic toxicity damaged the epidermal and cortical layers of the root as well as reduced the pore diameter of the cortical cells. However, the diameter of cortical cells pores in magnetoprimed plants was observed higher as compared to plants emerged from non-primed seeds at all level of As toxicity. Thus, the study suggested that magnetopriming has the potential to attenuate the toxic effect of As and could be employed as a pre-sowing treatment to reduce the phytotoxic effects of metal ions in plants by improving root architecture and root tolerance index. This study is the very first exploration of the potential benefits of magnetopriming in mitigating the toxicity of metals (As) in plant roots utilizing the micro-CT technique.

Characterizing the effects of particle interaction and the influence of the fabric of granular materials is one of the primary challenges in studying the constitutive behavior of granular materials. The evolution of the fabric of granular materials and their response to applied stresses have been investigated extensively in the literature. Contact number is one of the most common metrics used to assess the evolution of the fabric of granular materials subjected to external loading. However, contact number is a limited metric as it incorporates only the effect of the particles in contact with a specific particle; it cannot be used to characterize the evolution of the fabric of granular materials at a mesoscale. A new metric that can incorporate the effect of particles in direct contact with a specific particle (as well as other particles within its vicinity) is much more powerful in characterizing the evolution of granular material fabric. Subgraph centrality (SC) is a complex network property that describes the change in the number of closed cycles in a network and represents a new metric for characterizing the contact network of the particles at the particle scale and mesoscale. 3D Synchrotron micro-computed tomography images (SMT) and SC were used to characterize the evolution of the fabric in five specimens, which were composed of two different types of silica sand particles subjected to axisymmetric triaxial loading. The effects of the specimens' initial density, confining pressure, kinematics of the particles, and particle morphology on the evolution of the contact network of the particles were investigated. The evolution of four node structures as one of the underlying fabric structures within the specimen was investigated to illustrate how the structure of the specimens was evolving and causing the change in the SC of the particles. Variation in the average SC of the specimens was correlated with their volumetric strain to demonstrate the relationship between the change in the contact structure of the particles and the constitutive behavior of sheared sand.