Early detection of toxigenic fungi on maize by hyperspectral imaging analysis

Fungi can grow on many food commodities. Some fungal species, such as Aspergillus flavus, Aspergillus parasiticus, Aspergillus niger and Fusarium spp., can produce, under suitable conditions, mycotoxins, secondary metabolites which are toxic for humans and animals. Toxigenic fungi are a real issue, especially for the cereal industry. The aim of this work is to carry out a non destructive, hyperspectral imaging-based method to detect toxigenic fungi on maize kernels, and to discriminate between healthy and diseased kernels. A desktop spectral scanner equipped with an imaging based spectrometer ImSpector- Specim V10, working in the visible-near infrared spectral range (400-1000 nm) was used. The results show that the hyperspectral imaging is able to rapidly discriminate commercial maize kernels infected with toxigenic fungi from uninfected controls when traditional methods are not yet effective: i.e. from 48 h after inoculation with A. niger or A. flavus.     

Poly(vinyl alcohol)‐Based Film Potentially Suitable for Antimicrobial Packaging Applications

This work aimed at developing a thin and water‐resistant food‐grade poly(vinyl alcohol) (PVOH)‐based matrix able to swell when in contact with high moisture content food products without rupturing to release antimicrobial agents onto the food surface. This film was prepared by blending PVOH and 7.20% (wt/wt of PVOH) of poly(ethylene glycol) (PEG) with citric acid as crosslinking agent. The film‐forming solution was then casted onto a flat surface and the obtained film was 60 μm in thickness and showed a good transparency (close to T = 100%) in the visible region (400 to 700 nm). After immersion in water for 72 h at room temperature, the crosslinked matrix loses only 19.2% of its original weight (the percentage includes the amount of unreacted crosslinking agent, antimicrobial in itself). Water content, degree of swelling, and crosslinking density of the film prove that the presence of PEG diminishes the hydrophilic behavior of the material. Also the mechanical properties of the wet and dry film were assessed. Alongside this, 2.5% (wt/wt of dry film) of grapefruit seed extract (GSE), an antimicrobial agent, was added to the film‐forming solution just before casting and the ability of the plastic matrix to release the additive was then evaluated in vitro against 2 GSE‐susceptible microorganisms, Salmonella enteritidis and Listeria innocua. The results indicate that the developed matrix may be a promising food‐grade material for the incorporation of active substances.     

Characterization of plasma-sprayed coatings using nondestructive evaluation techniques: Round-robin test results

A round-robin test was implemented where nine European research institutions and universities applied different thermal, ultrasonic, and magnetic methods for measuring the thickness of plasma-sprayed coatings. The coatings, which had thicknesses ranging from 50 to 500 μm, were applied on substrates of AISI 316, a standard industrial structural material, and on Armco iron in order to have a material of known thermal properties. Destructive testing was performed after the other methods had been applied, resulting in detailed information on the coating thickness, rugosity, and uniformity. The results obtained with the applied methods on the two unknown samples for each substrate type agreed within 20% with the destructive testing data. This article was first published in INSIGHT—Non-Destructive Testing and Condition Monitoring, The Journal of The British Institute of Non-Destructive Testing, Vol 39 (No. 12), Dec 1997, and appears here with the permission of The British Institute of Non-Destructive Testing and the authors. This article was composed by the working group; see Acknowledgment.     

Raman investigation of air-stable silicene nanosheets on an inert graphite surface

The fascinating properties of two dimensional (2D) crystals have gained increasing interest for many applications. The synthesis of a 2D silicon structure, namely silicene, is attracting great interest for possible development of next generation electronic devices. The main difficulty in working with silicene remains its strong tendency to oxidation when exposed to air as a consequence of its relatively highly buckled structure. In this work, we univocally identify the Raman mode of air-stable low-buckled silicene nanosheets synthesized on highly oriented pyrolytic graphite (HOPG) located at 542.5 cm?1. The main focus of this work is Raman spectroscopy and mapping analyses in combination with ab initio calculations. Scanning tunneling microscopy images reveal the presence of a patchwork of Si three-dimensional (3D) clusters and contiguous Si areas presenting a honeycomb atomic arrangement, rotated by 30° with respect to the HOPG substrate underneath, with a lattice parameter of 0.41 ± 0.02 nm and a buckling of the Si atoms of 0.05 nm. Raman analysis supports the co-existence of 3D silicon clusters and 2D silicene. The Raman shift of low-buckled silicene on an inert substrate has not been reported so far and it is completely different from the one calculated for free-standing silicene and the ones measured for silicene grown on Ag(111) surfaces. Our experimental results are perfectly reproduced by our ab initio calculations of deposited silicene nanosheets. This leads us to conclude that the precise value of the observed Raman shift crucially depends on the strain between the silicene and the HOPG substrate.

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A Round Robin Test for buildings energy performance in Italy

The energy policy in Europe regarding buildings and the energy efficiency sector are regulated by two directives: 2002/91/CE - EPBD and 2006/32/CE - EEESD [1] and [2].The CEN has elaborated a standard to revise all European normatives about building energy performance and HVAC plants. The “CEN Umbrella” CEN/TR 15615 [3] includes a new version of EN ISO 13790:2008 [4] and a new standard about heating plant, use and contributions of renewable energy sources. Furthermore, the CEN Standard provides a software version for technicians.In this paper we present a Round Robin Test between a selection of softwares applied to an Italian case study. The selected calculation methodologies, range from research packages to extra-simplified software. Furthermore, the Italian procedure described in UNI TS 11300 [5] has been analyzed and considered as the reference for all other calculation methodologies.The results of the Round Robin Test show the relationship between thoroughness of data input and energy evaluation accurancy. The more the input data is affected by uncertainty, the less precise is the energy efficiency calculation. On the other hand the energy performance of building evaluation accurancy depends on the aim of the simulation: the energy audit, the energy design or the energy labeling (certification).     

LaTiOxNy Thin Film Model Systems for Photocatalytic Water Splitting: Physicochemical Evolution of the Solid–Liquid Interface and the Role of the Crystallographic Orientation

The size of the band gap and the energy position of the band edges make several oxynitride semiconductors promising candidates for efficient hydrogen and oxygen production under solar light illumination. Intense research efforts dedicated to oxynitride materials have unveiled the majority of their most important properties. However, two crucial aspects have received much less attention: One is the critical issue of compositional/structural surface modifications that occur during operation and how these affect photoelectrochemical performance. The second concerns the relation between electrochemical response and the crystallographic surface orientation of the oxynitride semiconductor. These are indeed topics of fundamental importance, since it is exactly at the surface where the visible‐light‐driven electrochemical reaction takes place. In contrast to conventional powder samples, thin films represent the best model system for these investigations. This study reviews current state‐of‐the‐art oxynitride thin film fabrication and characterization, before focusing on LaTiO₂N, selected as a representative photocatalyst. An investigation of the initial physicochemical evolution of the surface is reported. Then, it is shown that after stabilization the absorbed photon‐to‐current conversion efficiency of epitaxial thin films can differ by about 50% for different crystallographic surface orientations, and be up to 5 times larger than for polycrystalline samples.     

Perfluoropolyether-based organic-inorganic coatings

In the present paper a comprehensive analysis on the preparation and characterization of organic-inorganic hybrids containing perfluoropolyethers (PFPE) as organic component and silica (in situ generated from tetraethoxysilane by means of the sol-gel process) as inorganic counterpart is reported. PFPE with different molecular weights and functionalities have been used in order to improve the miscibility with respect to other reactants and solvents comprising the final formulation of the coating. In this respect, PFPE oligomers have been used with or without chain extension with polycaprolactone segments. The hybrids have been applied with different techniques onto glass substrates as functional coatings and the effects of different molecular structures, molecular weights and organic-inorganic ratios have been thoroughly investigated in terms of surface properties (i.e. water and oil wettability and surface segregation of PFPE segments).