High-frequency scattering by objects buried in lossy media

The uniform geometrical theory of diffraction (UTD) is extended so that it can be used to calculate the scattering from an object buried in a lossy medium. First, the accuracy of this high frequency method is examined by comparing numerical results for the scattering by a polygonal cylinder in a lossy medium of infinite extent with calculations based on a method of moments (MoM) solution. Next, the more difficult scattering problem of a polygonal cylinder in a lossy half space is treated. The UTD solution for the unbounded region is employed together with the fields of rays introduced by the interface between air and the lossy medium to obtain expressions for the scattered field in air and in the lossy medium     

Electromagnetic diffraction of an obliquely incident plane wave bya right-angled anisotropic impedance wedge with a perfectly conductingface

The diffraction of an arbitrarily polarized electromagnetic plane wave obliquely incident on the edge of a right-angled anisotropic impedance wedge with a perfectly conducting face is analyzed. The impedance tensor on the loaded face has its principal anisotropy axes along directions parallel and perpendicular to the edge, exhibiting arbitrary surface impedance values in these directions. The proposed solution procedure applies both to the exterior and the interior right-angled wedges. The rigorous spectral solution for the field components parallel to the edge is determined through the application of the Sommerfeld-Maliuzhinets technique. A uniform asymptotic solution is provided in the framework of the uniform geometrical theory of diffraction (UTD). The diffracted field is expressed in a simple closed form involving ratios of trigonometric functions and the UTD transition function. Samples of numerical results are presented to demonstrate the effectiveness of the asymptotic expressions proposed and to show that they contain as limit cases all previous three-dimensional (3-D) solutions for the right-angled impedance wedge with a perfectly conducting face     

Biogenic amine content and microbiological profile of Pecorino di Farindola cheese

“Pecorino di Farindola” is a traditional ewes’ milk cheese produced in the Abruzzo region (Italy) and ripened for a minimum of 90 days. The main objective of this research was to characterize the microbiological and chemical composition of this cheese, manufactured in ten dairy farms during the winter cheese-making season (December through March). By using classical enumeration system on specific media variability was observed in the viable numbers of aerobic mesophilic bacteria, enterobacteria, coagulase-negative staphylococci, yeasts, enterococci, mesophilic and thermophilic lactobacilli, lactococci and thermophilic streptococci. Salmonella spp., Listeria monocytogenes and Escherichia coli O157:H7 resulted to be absent in all the samples. Among compounds possibly impacting on human health, the isomer cis-9, trans-11 conjugated linoleic acid (CLA), was determined in high levels in all samples, ranging from 9.2 to 12.7 mg/g fat. Great diversity was also found in biogenic amine contents with a relevant presence of tyramine in all the cheeses. This work represents the first study on Pecorino di Farindola cheese and could contribute to deepen the knowledge on its microbiological and biochemical features, focusing on hygiene and consumer health aspects.     

Method for studying the effects of thermal deformations on optical systems for space application

In this paper, the results of the thermo-elastic analysis performed on the stereo channel of the imaging system Integrated Observatory System for the BepiColombo European Space Agency mission to Mercury are presented. The aim of the work is to determine the effects of ambient parameter variations on the equipment performance; the optical performance is changing during the mission lifetime primarily because of the optics misalignments and deformations induced by temperature variations. The camera optics and their mountings are modeled and processed by a thermo-mechanical finite element model (FEM) program, which reproduces the expected optics and structure thermo-elastic deformations in the instrument foreseen operative temperature range, i.e., between -20 °C and 30 °C. The FEM outputs are elaborated using a MATLAB optimization routine: an algorithm based on nonlinear least square data fitting is adopted to determine the surface equation (plane, spherical, nth polynomial) which best fits the deformed optical surfaces. The obtained surfaces are then directly imported into a ZEMAX code for sequential ray-tracing analysis. Variations of the optical spot diagrams, modulation transfer function curves, and ensquared energy are then computed. The overall analysis shows that the preferred solution for mounting the optical elements is adopting the kinematic constraints instead of using the classical glue solution.     

Evaluation of microstructural properties of coffee beans by synchrotron X-ray microtomography: a methodological approach

Synchrotron radiation microtomography was used as a nondestructive imaging technique to investigate the microstructural properties of green and roasted coffee beans. After image acquisition, 2D images have been reconstructed and 3D images of the beans have been then obtained. Qualitative and quantitative analysis of the images allow to fully characterize the morphological and structural features of the coffee beans. Roasting causes meaningful changes in the microstructure of the coffee bean tissue with the development in the entire bean of a porous structure with pores of different shape and size depending on the zone of the bean and cracks occurring mainly in the more external regions and between parenchyma and mucilage. The highly contrasted X-ray images have been analyzed to determine the pore size and its distribution in different regions of the coffee beans by selecting Volume-of-Interest (VoI). The use of phase-contrast hard X-rays imaging techniques represents an interesting tool of investigation of the internal structure, morphology, as well as the quality of whole coffee beans. Moreover, the high potentiality of 3D X-ray imaging and the approach used in this study could be applied in understanding the effects of roasting process conditions on the evolution of microstructural properties of the bean that may affect the stability as well the grinding and brewing performances. PRACTICAL APPLICATION: Synchrotron radiation microtomography is an elegant nondestructive imaging technique to investigate the microstructural properties of porous cellular matrices like the green and roasted coffee beans. The quantitative analysis of the resulting 2D and 3D images allows a more comprehensive and objective characterization of the sample under investigation as a whole or of extracted Volumes-of-Interest in the bean. This imaging technique could have a major role in understanding the effects of roasting process conditions on the microstructural properties of the bean.     

Predictors of societal and professional impact of orthodontic research. A multivariate,scientometric approach

Scientometrics - The aim of this study was to identify the factors that predict societal and professional impact of orthodontic research and determine the orthodontic research articles that...     

Determination of phthalate esters in wine using solid-phase extraction and gas chromatography–mass spectrometry

A method for the determination of six phthalate esters in wine samples has been developed. The phthalates were extracted from wine samples with an optimised solid-phase extraction method on C18 column and quantification was achieved via gas chromatography coupled with a mass spectrometer. The method was linear between 0.015 and 5.000 μg mL⁻¹ for DMP, DEP and DEHP and between 0.018 and 5.000 μg mL⁻¹ for iBP, DBP and BBP. The LOQs of DMP, DEP and DEH were 0.024 μg mL⁻¹ while those of iBP, DBP and BBP were 0.029 μg mL⁻¹. The intra-day method repeatability was between 10% and 15% RSD, whereas the inter-day method repeatability was between 13% and 21% RSD. A survey was performed on white and red wines (n = 62) from the market, winemakers and an experimental pilot plant. All the analysed samples were phthalate contaminated. Commercial wine showed higher detection frequency and level of total phthalate, DBP and BBP than those produced in a pilot plant. iBP and DEHP concentrations were similar in all the groups of samples. iBP concentration was higher in red wines than in white ones.     

The diffraction of an inhomogeneous plane wave by an impedancewedge in a lossy medium

The diffraction of an inhomogeneous plane wave by an impedance wedge embedded in a lossy medium is analyzed. The rigorous integral representation for the field is asymptotically evaluated in the context of the uniform geometrical theory of diffraction (UTD) so that the asymptotic expressions obtained can be employed in a ray analysis of the scattering from more complex edge geometries located in a dissipative medium. Surface wave excitations at the edge and their propagation along the wedge faces are discussed with particular emphasis on the effects of losses     

A UTD solution for the scattering by a wedge with anisotropicimpedance faces: skew incidence case

Asymptotic expressions for the fields scattered by an anisotropic impedance wedge at oblique incidence are derived in the context of the uniform geometrical theory of diffraction (UTD). They are obtained by resorting to a perturbative approach, considering the normal incidence case as the imperturbed configuration. We observe that the limits of applicability of this approximate analytical solution extend far beyond those of standard perturbative approaches, allowing us to account for deviations from the normal incidence case of 20° to 30°