BEM approach to protection of structures from seismic waves by a viscoelastic stratum

In the context of the anti-plane problem, we study harmonic oscillations of an elastic rectangle whose base is isolated from the foundation by a viscoelastic stratum of finite thickness. Such a (viscoelastic) medium is embedded in the ground, which is simulated as a homogeneous isotropic elastic half-space. By using the fundamental representation of solution through single and double layer potentials, the problem is reduced to a set of integral equations. The main practical aspect of this investigation is connected with seismic base isolation. We thus estimate the wave attenuation, which results in the decrease of the vibration amplitude for the rectangular construction, provided by the viscoelastic stratum.     

Fatty Acid Composition of Freshwater Wild Fish in Subalpine Lakes: A Comparative Study

In this study, the proximate and fatty acid compositions of the muscle tissue of 186 samples of fish belonging to fifteen species of freshwater fish harvested in subalpine lakes (bleak, shad, crucian carp, whitefish, common carp, pike, black bullhead, burbot, perch, Italian roach, roach, rudd, wels catfish, chub and tench) were investigated. Most of the fish demonstrated a lipid content in the fillet lower than 2.0 g 100 g^?1 wet weight (range 0.6–9.7). A strong relationship between feeding behavior and fatty acid composition of the muscle lipids was observed. Planktivorous fish showed the lowest amounts of n‐3 fatty acids (p < 0.05), but the highest monounsaturated fatty acid (MUFA) contents, in particular 18:1n‐9. Conversely, carnivorous fish showed the highest amounts of saturated fatty acids and n‐3 fatty acids (p < 0.05), but the lowest MUFA contents. Omnivorous fish showed substantial proportions of n‐3 fatty acids and the highest contents of n‐6 fatty acids. Principal component analysis showed a distinct separation between fish species according to their feeding habits and demonstrated that the most contributing trophic markers were 18:1n‐9, 18:3n‐3, 22:6n‐3 and 20:4n‐6. The quantitative amounts n‐3 polyunsaturated fatty acid in muscle tissues varied depending on the fish species, the lipid content and the feeding habits. Some species were very lean, and therefore would be poor choices for human consumption to meet dietary n‐3 fatty acid requirements. Nevertheless, the more frequently consumed and appreciated fish, shad and whitefish, had EPA and DHA contents in the range 900–1,000 mg 100 g^?1 fresh fillet.     

A Peltier cells differential calorimeter with kinetic correction for the measurement of cp(H,T) and Δs(H,T) of magnetocaloric materials

In this paper we describe and test a setup for the characterization of the magnetocaloric effect around room temperature. The setup is a differential calorimeter able to measure both the specific heat c(p)(H,T) under constant magnetic field H and the isothermal entropy change induced by changing H, Δs(H,T), in the room temperature range. The setup uses miniaturized Peltier cells to measure the heat flux, with resolution of about 1 μW, and power Peltier cells to regulate the temperature in the range from 243 K (-30 °C) to 343 K (+70 °C). The kinetic effects due to the heat capacity of the measuring cells are taken into account by a simple model of the heat flux diffusion in the calorimetric cell. As measurement examples, we show the characterization of the magnetocaloric effect in magnetic materials with a second order transition [without latent heat and without hysteresis, as in the La(1)(Fe(1-x-y)Co(y)Si(x))(13) alloy with x=0.077 and y=0.079] and with a first order transitions (with latent heat and hysteresis as in Ni(50)Mn(36)Co(1)Sn(13)). As a result we compare the entropy change Δs(H,T) derived from (i) the integration of the specific heat c(p)(H,T) and (ii) the direct isothermal measurements, obtaining an excellent agreement.     

A fuzzy logic procedure for ventilation control in case of fire in long tunnels

Ventilation is a crucial element while managing fire events in tunnels. This paper deals with ventilation strategies to be applied in case of fire in a long tunnel. The Frejus road tunnel has been considered as an application. This is a single tube road tunnel with semi-transversal ventilation. Ordinary and emergency ventilations are operated by using dedicated supply and extraction ducts.     

Study of the Coupling of Terahertz Radiation to Heterostructure Transistors with a Free Electron Laser Source

High electron mobility transistors can work as room-temperature direct detectors of radiation at frequency much higher than their cutoff frequency. Here, we present a tool based on a Free Electron Laser source to study the detection mechanism and the coupling of the high frequency signal into the transistor channel. We performed a mapping over a wide area of the coupling of 0.15 THz radiation to an AlGaN/GaN transistors with cut-off frequency of 30 GHz. Local, polarization-dependent irradiation allowed us to selectively couple the signal to the channel either directly or through individual transistor bias lines, in order to study the nonlinear properties of the transistor channel. Our results indicate that HEMT technology can be used to design a millimeter-wave focal plane array with integrated planar antennas and readout electronics.     

Study of green Sicilian table olive fermentations through microbiological,chemical and sensory analyses

The production of five different green table olive cultivars was studied by a combined strategy consisting of chemical, microbiological and sensory analyses. Cultivable microflora of samples collected during processing was monitored by plate counts on seven synthetic culture media. In all samples Enterobacteriaceae, Pseudomonaceae, staphylococci, lactic acid bacteria and spore-forming bacteria were undetectable. Yeasts and moulds were countable from the day 42 (2 log CFU/ml) till the end of fermentation (6 log CFU/ml). The use of three different approaches for microorganism detection, including a culture-independent methodology, revealed the presence of barely three yeast species during the entire fermentation period: Candida parapsilosis, Pichia guilliermondii and Pichia kluyveri. Biochemical features of technological interest were evaluated for 94 strains in order to investigate their potential role in fermentation of green Sicilian table olives.     

Spatial distribution of ochratoxin A in vineyard and sampling design to assess must contamination

The aim of this work was to study the spatial variability of ochratoxin A (OTA) in vineyards and to define a reliable sampling protocol for bunches in order to assess OTA content before harvesting. In 2002, two vineyards with 'Negroamaro' and 'Sangiovese' grape varieties were chosen in Southern Italy. The same sampling design was applied to both vineyards. Ten plants were collected from the X-shaped path of the whole vineyard (plants 1 through 10) and 10 plants from the two central cross-perpendicular lines (plants 11 through 20). Bunches harvested from plants 1 through 10 were numbered progressively, weighed, and crushed separately, and bunches obtained from plants 11 through 20 were crushed plant by plant. Juices obtained were analyzed for OTA content by high-performance liquid chromatography. Then, a simulated approach for sampling was applied, following randomized and systematic designs. High and random variability was observed in OTA content both among bunches and among plants in the two vineyards, independent of contamination level. Simulated sampling design markedly influenced the assessment of must contamination. The best results were obtained when sampling involved one bunch per plant, in a predefined position, from at least 10 plants. Estimated means, obtained with different sampling designs, did not differ significantly from calculated mean OTA content. If the true contamination in a vineyard is 2 microg kg(-1), the limit fixed in Europe for OTA content in must and wine, the range of OTA content assessed sampling one bunch in the central position of 10 plants should lie between 2.9 and 1.4. The accuracy could be considered acceptable.     

Application of quantitative real-time PCR in the detection of prion-protein gene species-specific DNA sequences in animal meals and feedstuffs

This study describes a method for quantitative and species-specific detection of animal DNA from different species (cattle, sheep, goat, swine, and chicken) in animal feed and feed ingredients, including fish meals. A quantitative real-time PCR approach was carried out to characterize species-specific sequences based on the amplification of prion-protein sequence. Prion-protein species-specific primers and TaqMan probes were designed, and amplification protocols were optimized in order to discriminate the different species with short PCR amplicons. The real-time quantitative PCR approach was also compared to conventional species-specific PCR assays. The real-time quantitative assay allowed the detection of 10 pg of ruminant, swine, and poultry DNA extracted from meat samples processed at 130 degrees C for 40 min, 200 kPa. The origin of analyzed animal meals was characterized by the quantitative estimation of ruminant, swine, and poultry DNA. The TaqMan assay was used to quantify ruminant DNA in feedstuffs with 0.1% of meat and bone meal. In conclusion, the proposed molecular approach allowed the detection of species-specific DNA in animal meals and feedstuffs.     

Metal-enhanced fluorescence of colloidal nanocrystals with nanoscale control

Engineering the spectral properties of fluorophores, such as the enhancement of luminescence intensity, can be achieved through coupling with surface plasmons in metallic nanostructures. This process, referred to as metal-enhanced fluorescence, offers promise for a range of applications, including LEDs, sensor technology, microarrays and single-molecule studies. It becomes even more appealing when applied to colloidal semiconductor nanocrystals, which exhibit size-dependent optical properties, have high photochemical stability, and are characterized by broad excitation spectra and narrow emission bands. Other approaches have relied upon the coupling of fluorophores (typically organic dyes) to random distributions of metallic nanoparticles or nanoscale roughness in metallic films. Here, we develop a new strategy based on the highly reproducible fabrication of ordered arrays of gold nanostructures coupled to CdSe/ZnS nanocrystals dispersed in a polymer blend. We demonstrate the possibility of obtaining precise control and a high spatial selectivity of the fluorescence enhancement process.