Small-scale crack blunting at a bimaterial interface with Coulomb friction

The deformation field near the tip of a tensional crack impinging upon a normally loaded bimaterial frictional interface is studied. By allowing the two materials to slide with respect to each other along the interface the high stresses around the crack tip are relaxed. The region of slip as well as the stress distribution inside the slip zone is obtained as a function of the far field loading parameter.     

Detection and Identification of Probiotic Lactobacillus plantarum Strains by Multiplex PCR Using RAPD-Derived Primers

Lactobacillus plantarum 2035 and Lactobacillus plantarum ACA-DC 2640 are two lactic acid bacteria (LAB) strains that have been isolated from Feta cheese. Both display significant potential for the production of novel probiotic food products. The aim of the present study was the development of an accurate and efficient method for the molecular detection and identification of the above strains in a single reaction. A multiplex PCR assay was designed for each strain, based on specific primers derived from Random Amplified Polymorphic DNA (RAPD) Sequenced Characterized Amplified Region (SCAR) analysis. The specificity of the assay was tested with a total of 23 different LAB strains, for L. plantarum 2035 and L. plantarum ACA-DC 2640. The multiplex PCR assay was also successfully applied for the detection of the above cultures in yogurt samples prepared in our lab. The proposed methodology may be applied for monitoring the presence of these strains in food products, thus evaluating their probiotic character. Moreover, our strategy may be adapted for other novel LAB strains with probiotic potential, thus providing a powerful tool for molecular discrimination that could be invaluable to the food industry.     

Seismic displacements of landfills and deformation of geosynthetics due to base sliding

Seismic design of waste landfills has been a subject of intense research over the past two decades, primarily due to the severe environmental impact of a potential failure. The majority of the related studies have been focused on the stability assessment of landfills utilizing permanent deformation methods. However, previous investigations have not fully addressed the impact of the composite liner system on the seismic performance of the geostructure, mainly expressed as potential sliding development, which is greatly affected by the geometry and the resulting initial static stress state of the landfill. Therefore, the aforementioned issues are investigated via a detailed parametric study, where the dynamic behaviour of the composite liner system is examined both analytically and numerically. The conducted coupled analyses indicated that the most significant parameters of the complex dynamic response of waste landfills can be reduced in two ratios that comprise functions of the main characteristics of the geostructure and of the excitation. Moreover, two distinct failure patterns have been identified with respect to the characteristics of the distribution of the permanent displacements along the interface and the axial deformation along the geosynthetic. The occurrence conditions of these failure patterns can be determined in terms of the two abovementioned ratios as verified by the analytical results of the critical acceleration of a simple SDOF system.     

Bonding behaviour of chemically modified wood particles for board production

The objective of this paper was to evaluate the bonding behaviour of chemically modified wood particles towards an isocyanate resin system, as determined from internal bond strength of the board, and to determine which resin system, isocyanate or formaldehyde is suitable for use in boards made from modified raw material. It was found that chemical modification of wood chips and strands did not significantly affect the bonding efficiency of isocyanate resin, but the bonding efficiency of formaldehyde resins was strongly influenced. This behaviour can be a consequence of the usage of a less pH dependent resin that is fully cured during hot pressing in combination with the high mobility of the resin which causes penetration to considerable depth into compressed particles repairing weak zones, which are created during the modification process as chips are exposed to elevated temperatures, by sticking them together. It is suggested therefore, that the isocyanate resin system is more suitable for use in boards made from modified raw material than the formaldehyde resin system.     

Predictors and correlates of taste preferences in European children: The IDEFICS study

The present study investigated taste preferences in a sample of 1705 children aged 6 to 9 years from survey centres in Italy, Estonia, Cyprus, Belgium, Sweden, Germany, Hungary, and Spain and aimed to identify factors correlated with taste preference. Children’s preferences for varying levels of sucrose (sweet) in apple juice and fat, sodium chloride (salt) and monosodium glutamate (umami) in crackers were assessed using paired-comparison tests. Socio-demographics (age, sex, parental education), early feeding practises (breastfeeding, introduction of fruits), parenting behaviour (TV viewing, using food as a reward) and taste threshold sensitivity for sucrose (sweet), sodium chloride (salt), caffeine (bitter) and monosodium glutamate (umami) were investigated as possible correlates of taste preferences. Parents reported on socio-demographics, early feeding and parenting behaviour. Taste thresholds were determined via a paired-comparison staircase method. Country of residence was the strongest factor related to preferences for all four tastes. Taste preferences also differed by age. Preference for sugar and salt increased between 6 and 9 years of age while preference for monosodium glutamate decreased. The age differences remained significant even after adjustment for sex, country of residence, parental education and early feeding habits. Sex, parental education, early feeding habits, TV viewing, using food as a reward and taste thresholds were not consistently related to taste preferences among the survey centres. In summary, the results highlight the importance of culture and age in taste preferences in children younger than 10 years of age.     

Valuing a wind farm construction: A contingent valuation study in Greece

Our analysis is based on data from a double-bounded dichotomous choice contingent valuation study implemented to elicit public attitudes towards renewable energy generation and their willingness to pay for the construction of a wind farm in the area of Messanagros in the island of Rhodes, Greece. Results indicate that there are significant positive values deriving from the proposed project. Respondents report a mean willingness to pay a premium in their bi-monthly electric bills of €8.86 for the sole purpose of the construction of the wind farm. The estimated economic benefits to the local population are weighed against the investment cost in a cost–benefit analysis to inform policy making and implications for EU energy policy are provided.     

Photonic bandgap fibre oscillators and amplifiers

In the search for ever higher output power or energy from fibre oscillators or amplifiers a nowadays mature technology relies on enlarging the fibre mode area. Broadening of the core diameter, all other things being equal, inevitably yields a multimode fibre, thereby dramatically limiting the device usefulness. Various strategies have been deployed to design and manufacture single transverse mode fibre oscillators and amplifiers, among which making use of the so-called photonic bandgap effect to restrict the modal population seems promising. Helped by efficient and reliable numerical tools the design of large mode area singlemode photonic bandgap fibres is presented. Two fibres with 20-μm and 40-μm core diameter, both of them heavily doped with Yb³⁺ ions, have been fabricated by the widespread modified chemical vapour deposition process and are shown to behave properly when used as the core element of either continuous wave oscillators or femtosecond amplifiers. Good output beam quality (M² parameter spanning from 1.12 to 1.5 for the set of fibres studied) and high slope efficiency of 80% in cw oscillation regime are demonstrated. Furthermore the 40-μm core diameter fibre is shown to be resilient to tight bending down to 7.5-cm radius. The stack-and-draw process makes it easy to tailor the outer cladding so that a large numerical aperture can be reached. Subsequently, from this air-clad fibre, 500 fs 47 W pulses at 35 MHz are obtained from a two-stage chirped pulse amplification system.     

Determination of sulphur and copper depth distribution in patina layers using nuclear reaction techniques

A method for Cu and S profiling in patina layers was developed by applying a combination of nuclear reaction analysis (NRA) and Rutherford backscattering spectroscopy (RBS). The copper profiling was performed by using the 1327 keV γ-ray deexciting the third excited state to the ground state of ⁶³Cu produced by the reaction ⁶³Cu(p,p^′γ)⁶³Cu. For the determination of sulphur the 2230 keV γ-ray was used deexciting the first excited state to the ground state of ³²S formed through the reaction ³²S(p,p^′γ)³²S, which exhibits three sharp resonances at projectile energies 3.094, 3.195 and 3.379 MeV. The relevant cross-sections were measured in the energy range between 3.0 and 3.7 MeV in steps of 20 keV at 125° to the incident proton beam direction. The technique was tested using artificially produced and natural copper patina layers. Supporting information on the depth distribution of the constituent elements of the patina samples was obtained by p-RBS (E_p: 1.5 MeV, θ: 160°).     

Distributed computation of averages over ad hoc networks

In this paper, we develop algorithms for distributed computation of averages of the node data over networks with arbitrary but fixed connectivity. The algorithms we develop are linear dynamical systems that generate sequences of improving approximations to the desired computation at each node, via iterative processing and broadcasting. The algorithms are locally constructed at each node by exploiting only locally available and macroscopic information about the network topology. We present methods for optimizing the convergence rates of these algorithms to the desired computation, and evaluate their performance characteristics in the context of a problem of signal estimation from multinode noisy observations. By conducting simulations based on simple power-loss propagation models, we perform a preliminary comparison of the algorithms we develop against other types of distributed algorithms for computing averages, and identify transmit-power optimized algorithmic implementations as a function of the size and density of the sensor network.     

In vivo studies on the role of the peripheral benzodiazepine receptor (PBR) in steroidogenesis

In various steroidogenic cell models, mitochondrial preparations and submitochondrial fractions, the expression of the mitochondrial 18 kDa peripheral-type benzodiazepine receptor (PBR) protein confers the ability to take up and release, upon ligand activation, cholesterol. Thus, cholesterol becomes available to P450scc on the inner mitochondrial membrane. These in vitro studies were validated by in vivo experiments. Treatment of rats with ginkgolide B (GKB), specifically reduced the ligand binding capacity, protein, and mRNA expression of the adrenocortical PBR and circulating glucocorticoid levels. Treatment with GKB also resulted in inhibition of PBR protein synthesis and corticosterone production by isolated adrenocortical cells in response to ACTH. The ontogeny of both PBR binding capacity and protein directly paralleled that of ACTH-inducible steroidogenesis in rat adrenal cells and in rats injected with ACTH. In addition, the previously described suppression of luteal progesterone synthesis in the pregnant rat by continuous in vivo administration of a gonadotropin-releasing hormone agonist may be due to decreased luteal PBR ligand binding and mRNA. These results suggest that (i) PBR is an absolute prerequisite for adrenocortical and luteal steroidogenesis, (ii) regulation of adrenal PBR expression may be used as a tool to control circulating glucocorticoid levels and (iii) the stress hypo-responsive period of neonatal rats may result from decreased adrenal cortical PBR expression.