Structural effects in UO2 thin films irradiated with U ions

This work presents the results of a detailed structural characterisation of irradiated and unirradiated single crystal thin films of UO2. Thin films of UO2 were produced by reactive magnetron sputtering onto (0 0 1), (1 1 0) and (1 1 1) single crystal yttria-stabilised zirconia (YSZ) substrates. Half of the samples were irradiated with 110 MeV 238U31+ ions to fluences of 5 × 1010, 5 × 1011 and 5 × 1012 ions/cm2 to induce radiation damage, with the remainder kept for reference measurements. It was observed that as-produced UO2 films adopted the crystallographic orientation of their YSZ substrates. The irradiation fluences used in this study however, were not sufficient to cause any permanent change in the crystalline nature of UO2. It has been demonstrated that the effect of epitaxial re-crystallisation of the induced radiation damage can be quantified in terms of kernel average misorientation (KAM) and different crystallographic orientations of UO2 respond differently to ion irradiation

Structural effects in UO₂ thin films irradiated with U ions

AbstractThis work presents the results of a detailed structural characterisation of irradiated and unirradiated single crystal thin films of UO2. Thin films of UO2 were produced by reactive magnetron sputtering onto (001), (110) and (111) single crystal yttria-stabilised zirconia (YSZ) substrates. Half of the samples were irradiated with 110MeV 238U31+ ions to fluences of 5×1010, 5×1011 and 5×1012ions/cm2 to induce radiation damage, with the remainder kept for reference measurements. It was observed that as-produced UO2 films adopted the crystallographic orientation of their YSZ substrates. The irradiation fluences used in this study however, were not sufficient to cause any permanent change in the crystalline nature of UO2. It has been demonstrated that the effect of epitaxial re-crystallisation of the induced radiation damage can be quantified in terms of kernel average misorientation (KAM) and different crystallographic orientations of UO2 respond differently to ion irradiation

Ising model on 3D random lattices: A Monte Carlo study

We report single-cluster Monte Carlo simulations of the Ising model on three-dimensional Poissonian random lattices with up to 128,000 approx. 503 sites which are linked together according to the Voronoi/Delaunay prescription. For each lattice size quenched averages are performed over 96 realizations. By using reweighting techniques and finite-size scaling analyses we investigate the critical properties of the model in the close vicinity of the phase transition point. Our random lattice data provide strong evidence that, for the available system sizes, the resulting effective critical exponents are indistinguishable from recent high-precision estimates obtained in Monte Carlo studies of the Ising model and \phi^4 field theory on three-dimensional regular cubic lattices.Comment: 35 pages, LaTex, 8 tables, 8 postscript figure

The current state of the use of large wood in river restoration and management

Trees fall naturally into rivers generating flow heterogeneity, inducing geomorphological features, and creating habitats for biota. Wood is increasingly used in restoration projects and the potential of wood acting as leaky barriers to deliver natural flood management by “slowing the flow” is recognised. However, wood in rivers can pose a risk to infrastructure and locally increase flood hazards. The aim of this paper is to provide an up-to-date summary of the benefits and risks associated with using wood to promote geomorphological processes to restore and manage rivers. This summary was developed through a workshop that brought together academics, river managers, restoration practitioners and consultants in the UK to share science and best-practice on wood in rivers. A consensus was developed on four key issues: (i) hydro-geomorphological effects, (ii) current use in restoration and management, (iii) uncertainties and risks, and (iv) tools and guidance required to inform process-based restoration and management

Componente microfungina lipolitica e termofila in compost

Composting is a valid valuable strategy to treat lipid-rich wastes, due to the rapid development of a thermophilic phase during which the lipids become more accessible to microorganisms and their lipases. In the present study the thermophilic microfungal component of compost of different origin was evaluated. Furthermore, the lipolytic activity of the strains was estimated using agar plates containing lipid substrates. 19 microfungal strains were detected, with thermotolerant species being dominant, followed by strictly thermophilic species. All the isolates, except Paecilomyces variotii, showed lipolytic activity, in a variable extent depending on the substrates and, for some of these, also according to the incubation temperature. In particular Malbranchea cinnamomea, Mortierella sp., Sepedonium sp. and two Thermomyces lanuginosus strains, degraded all the substrates considered. The introduction or the enrichment of these lipolytic microorganisms in the composting process of lipid-rich wastes could be of great utility considering also the flexibility of some of these in relation to temperature

Determinazione della comunità microfungina del suolo del ghiacciaio Dosdè

Il lavoro qui presentato si inserisce nell’ambito del progetto PRIN 2008 “Studio e conservazione della biodiversità fungina di habitat marginali freddi minacciati dai cambiamenti climatici” (2008AR8MX9 002), focalizzato sull’indagine della micocenosi dei suoli di alcune aree periglaciali Italiane. Avendo a disposizione dati pregressi (2, 1), ove possibile l’analisi della biodiversità della componente macro e microfungina dei suoli è stata indagata anche al fine di valutare il cambiamento della micocenosi avvenuto nel corso dell’ultimo decennio. Le aree periglaciali rappresentano siti di elevato interesse in termini di biodiversità; nei loro suoli la presenza di neve e ghiaccio permette di attenuare le escursioni termiche, di fungere da riserva d’acqua a rilascio lento e prolungato, divenendo così un fattore determinante per la composizione e la struttura delle comunità microbiche residenti. I funghi adattati a tali areali vengono così a rivestire un ruolo particolarmente importante, soprattutto se simbionti di specie pioniere, licheni e micorrize. Nei suoli del ghiacciaio Dosdè (Valtellina, provincia di Sondrio), sito incluso nel SIC (Site of Community Importance) IT2040012 “Val Viola Bormina - Ghiacciaio di Cima dei Piazzi” la biodiversità fungina globale è stata valutata mediante analisi DGGE. Campioni di suolo sottostanti la lettiera sono stati prelevati in triplicato durante il mese di luglio 2011 a tre diverse altitudini: livello A (2290 m b.s.l.), ove la vegetazione dominante è rappresentata da Rhododendron ferrugineum L. e Juniperus communis subsp. nana. (Willd.) Syme; livello B (2460 m b.s.l.) e livello C (2570 m m b.s.l.), caratterizzati dalla presenza di morene, con Saxifrago bryoidis-Poetum alpinae e Luzuletum alpino-pilosae, e di piani proglaciali, con Sieversio-Oxyrietum digynae (Androsacetum alpinae). Il DNA è stato estratto direttamente e amplificato con il primer ITS3, con le code arricchite in basi GC (40bp GC-clamp) all’estremo 5’, e il primer reverse ITS4. I profili delle comunità fungine ottenuti sono stati analizzati con l’ausilio di metodi di clusterizzazione UPGMA (Unweighted Pair Group Method With Arithmetic Averages). I pattern elettroforetici ottenuti hanno permesso di evidenziare una composizione microfungina omogenea fra i tre campioni esaminati all’interno delle stesse aree. L’analisi cluster basata sulla matrice di similarità, costruita considerando la stessa posizione delle bande relative ai vari campioni, ha dimostrato che le unità tassonomiche si aggregano in tre diversi cluster, indicando una differenza genotipica tra i popolamenti presenti nelle tre diverse altitudini. I valori dell’indice di biodiversità di Shannon-Weaver sono inversamente proporzionali all’altitudine, presentando valore più alto (1,6) al livello A, diminuendo gradualmente a 1,4 e 1,2, rispettivamente per il livello B e C. Questo innovativo approccio metodologico è stato attuato a supporto della tradizionale indagine microbiologica (crescita colturale ed identificazione morfo-tassonomica degli isolati) e si è dimostrato un efficace e valido strumento di determinazione della struttura delle comunità microfungin

Study of the occurrence of greenhouse microfungi in a botanical garden

Three greenhouses and the Central Garden of the Botanical Garden of Pavia were monitored for 1 year with the objective of investigating the occurrence of both airborne fungal spores and phylloplane fungi. By using an SAS air sampler, the higher fungal spore concentrations were detected in tropical and Mediterranean greenhouses. A total of 72 species belonging to 42 genera, some of which are related to the presence of plants ex situ, were isolated from Petri plates after exposure. Some airborne fungi, such as Aspergillus spp., Penicillium spp. and Conidiobolus spp., which are responsible for human allergies and respiratory problems, were also detected. Forty-four genera of phylloplane fungi were identified from leaves randomly collected from greenhouse plants. Most of the aerial fungal taxa isolated were also detected from the phylloplane. Some phytopathogenic taxa, as exemplified by Gliocladium vermoeseni, Graphium sp., Peronospora sp., and Zygosporium oscheoides, were isolated only from the phylloplane. The information obtained from qualitative and quantitative analysis of fungi can be a useful tool in the control of indoor air quality, thereby guaranteeing ex situ plant conservation and occupational health safety