Biodiversity and bioprospecting of fungal endophytes from the Antarctic plant Colobanthus quitensis

Microorganisms from extreme environments are considered as a new and valuable reservoir of bioactive molecules of biotechnological interest and are also utilized as tools for enhancing tolerance to (a)biotic stresses in crops. In this study, the fungal endophytic community associated with the leaves of the Antarctic angiosperm Colobanthus quitensis was investigated as a new source of bioactive molecules. We isolated 132 fungal strains and taxonomically annotated 26 representative isolates, which mainly belonged to the Basidiomycota division. Selected isolates of Trametes sp., Lenzites sp., Sistotrema sp., and Peniophora sp. displayed broad extracellular enzymatic profiles; fungal extracts from some of them showed dose-dependent antitumor activity and inhibited the formation of amyloid fibrils of α-synuclein and its pathological mutant E46K. Selected fungal isolates were also able to promote secondary root development and fresh weight increase in Arabidopsis and tomato and antagonize the growth of pathogenic fungi harmful to crops. This study emphasizes the ecological and biotechnological relevance of fungi from the Antarctic ecosystem and provides clues to the bioprospecting of Antarctic Basidiomycetes fungi for industrial, agricultural, and medical applications

Image texture analysis and colorimetry for the classification of uranium ore concentrate powders

In the context of nuclear security, uranium ore concentrates (UOCs) play an important role: they are traded in large quantities and this makes their use “out of regulatory control” a possible scenario. Once an incident of illicit trafficking o f n uclear m aterial is detected, an understanding of its origin and production process is required; this implies the necessity to use analytical techniques able to measure characteristic parameters (e.g. physical, chemical, isotopic characteristics of the nuclear materials) which are referred to, in the field o f t he n uclear f orensics, a s signatures. The present study investigates the potential of image texture analysis (i.e. the angle measure technique), combined with the spectrophotometric determination of colours for the evaluation of the origin of several UOCs. The use of different multivariate statistical techniques allows the categorization of about 80 different samples into a few groups of UOCs powders, which makes this approach a promising method complementing the already established methods in nuclear forensics

Physical and mechanical characterization of irradiated uranium dioxide with a broad burnup range and different dopants using acoustic microscopy

Scanning acoustic microscopy is a non-destructive technique that allows determining the local material elastic properties by measuring the velocity of acoustic waves propagating in matter. High frequency acoustic waves are generated by a piezoelectric transducer, focused and then detected by the same transducer after having interacted with the sample. This technique has been employed in the past to assess different types of irradiated nuclear fuel and unirradiated chemical analogues of UO2 and it has enabled to relate the Rayleigh wave velocity of propagation with the Young's modulus and the density of the material. In the present study, thanks to new measurements on irradiated fuel and to analysis of data from the open literature, the variation of the density with burnup is determined up to ~ 100 GWd·t−1M. The porosity is then determined taking account of the irradiated fuel matrix swelling. Finally, an expression is proposed describing Young's modulus as a function of burnup, that can be used in fuel performance calculation.JRC.G.III.8-Waste Managemen

Raman spectroscopy of uranium compounds and the use of multivariate analysis for visualization and classification

Raman spectroscopy was used on 95 samples comprising mainly of uranium ore concentrates as well as some UF4 and UO2 samples, in order to classify uranium compounds for nuclear forensic purposes, for the first time. This technique was selected as it is non-destructive and rapid. The spectra obtained from 9 different classes of chemical compounds were subjected to multivariate data analysis such as principal component analysis (PCA), partial least square-discriminant analysis (PLS-DA) and Fisher Discriminant Analysis (FDA). These classes were ammonium diuranate (ADU), sodium diuranate (SDU), ammonium uranyl carbonate (AUC), uranyl hydroxide (UH), UO2, UO3, UO4, U3O8 and UF4. Unsupervised PCA of full spectra shows fairly good distinction among the classes with some overlaps observed with ADU and UH. These overlaps are also reflected in the poorer specificities determined by PLS-DA. Higher values of sensitivities and specificities of remaining compounds were obtained. Supervised FDA based on reduced dataset of only 40 variables shows similar results to that of PCA but with closer clustering of ADU, UH, SDU, AUC. As a rapid and non-destructive technique, Raman spectroscopy is useful and complements existing techniques in multi-faceted nuclear forensics.JRC.E.7-Nuclear Safeguards and Forensic

Response of irradiated nuclear fuel rods to quasi-static and dynamic loads

This paper presents the methodology applied for the experimental and numerical investigation of the mechanical response of spent nuclear fuel rods under static and dynamic loads. The experimental activities were conducted at the JRC Karlsruhe where a 3-point bending test device and an impact tower have been developed and commissioned at the hot-cell facilities. Results are provided for two PWR samples. Load-displacement curves describe the mechanical response of the sample in the 3point bending tests, whereas an image analysis methodology has been developed to comprehend the sample's behaviour under dynamic loads (recorded using a high-speed camera). Finite Element Analysis (FEA) are used to simulate the rod's response based on static and transient structural models in ANSYS Mechanical.JRC.G.III.8-Waste Managemen