Rock partridge (Alectoris graeca graeca) population density and trends in central Greece

The rock partridge is an emblematic species of the Greek avifauna and one of the most important game species in the country. The present study, which combined long term in–situ counts with distance sampling methodology in central Greece, indicated that the species’ population in Greece is the highest within its European distribution, in contrast to all prior considerations. Inter–annual trends suggested a stable rock partridge population both within hunting areas and wildlife refuges, whereas during summer, the species presented significantly higher densities in altitudes of more than 1,000 m, most probably due to the effect of predation at lower zones. The similarity of population structure between wildlife refuges and hunting zones along with the stable population trends demonstrate that rock partridge harvest in the country is sustainable

Analytical and numerical analyses of the micromechanics of soft fibrous connective tissues

State of the art research and treatment of biological tissues require accurate and efficient methods for describing their mechanical properties. Indeed, micromechanics motivated approaches provide a systematic method for elevating relevant data from the microscopic level to the macroscopic one. In this work the mechanical responses of hyperelastic tissues with one and two families of collagen fibers are analyzed by application of a new variational estimate accounting for their histology and the behaviors of their constituents. The resulting, close form expressions, are used to determine the overall response of the wall of a healthy human coronary artery. To demonstrate the accuracy of the proposed method these predictions are compared with corresponding 3-D finite element simulations of a periodic unit cell of the tissue with two families of fibers. Throughout, the analytical predictions for the highly nonlinear and anisotropic tissue are in agreement with the numerical simulations

Sequential Structural and Fluid Dynamics Analysis of Balloon-Expandable Coronary Stents: A Multivariable Statistical Analysis

Several clinical studies have identified a strong correlation between neointimal hyperplasia following coronary stent deployment and both stent-induced arterial injury and altered vessel hemodynamics. As such, the sequential structural and fluid dynamics analysis of balloon-expandable stent deployment should provide a comprehensive indication of stent performance. Despite this observation, very few numerical studies of balloon-expandable coronary stents have considered both the mechanical and hemodynamic impact of stent deployment. Furthermore, in the few studies that have considered both phenomena, only a small number of stents have been considered. In this study, a sequential structural and fluid dynamics analysis methodology was employed to compare both the mechanical and hemodynamic impact of six balloon-expandable coronary stents. To investigate the relationship between stent design and performance, several common stent design properties were then identified and the dependence between these properties and both the mechanical and hemodynamic variables of interest was evaluated using statistical measures of correlation. Following the completion of the numerical analyses, stent strut thickness was identified as the only common design property that demonstrated a strong dependence with either the mean equivalent stress predicted in the artery wall or the mean relative residence time predicted on the luminal surface of the artery. These results corroborate the findings of the large-scale ISAR-STEREO clinical studies and highlight the crucial role of strut thickness in coronary stent design. The sequential structural and fluid dynamics analysis methodology and the multivariable statistical treatment of the results described in this study should prove useful in the design of future balloon-expandable coronary stents

Assessing traffic and environmental impacts of smart lockers logistics measure in a medium-sized municipality of Athens

Home deliveries and e-commerce activities have increased substantially in the recent years. This fact led to the increase of the number of last mile trips in urban areas contributing immensely to the overall impacts on the urban environment. Communities are called to find smart solutions to alleviate these impacts, providing at the same time efficient logistics operation, service quality and user satisfaction. “Smart lockers” is a novel city logistics measure aiming at mitigating issues generated from the last mile of parcel deliveries, thus promoting the principles of sustainable urban mobility. In the present study a microscopic simulation of freight traffic flows was performed in a medium-sized municipality of Athens, Greece. Actual delivery data were obtained from a well-known logistics provider and used as input in PTV Vissim software in order to firstly assess the current operation of the deliveries in the study area. Further, an alternative scenario was developed, assuming that instead of home addresses, deliveries were made to the existing, though currently of limited use smart lockers network, assuming final collection of the order by the consumers. Consumers’ traveling options and preferences, were simulated in more sub-scenarios and results were compared to provide better understanding of the potential benefits arising by implementing the measure. Impacts on traffic (i.e. travel times and delays), as well as on the environment (i.e. emissions) were further assessed in a multicriteria framework which led to the estimation of the Logistics Sustainability Indices of the tested scenarios. © Springer Nature Switzerland AG 2019

The interaction of ozone with polyphenylsulfide thin films studied by ellipsometry and SPR

Thin films of polyphenylsulfide (PPS) have been deposited onto silicon wafers and gold-coated glass slides by the method of spin coating. Ellipsometry and surface plasmon resonance (SPR) were performed in order to determine film thickness and index of refraction. It was found that the derived film thickness depends on spin speed as omega(-s), with s varying between 0.5 and 0.6, depending on the concentration of PPS solution, which was in good agreement with hydrodynamic theory. An accurate value of films' index of refraction of n = 1.59 was determined. The index of refraction of PPS films was found to increase on exposure to 2 ppm ozone. These results can be exploited for further development of real-time detection systems for ozone at low concentration based upon more sensitive optical techniques, such as integrated optic interferometry

Catalytic and electrocatalytic behavior of Ni-based cermet anodes under internal dry reforming of CH4 + CO2 mixtures in SOFCs

Summarization: A high temperature (700–900 °C) SOFC with yttria stabilized zirconia (YSZ) solid electrolyte was constructed and tested on direct feed of simulated biogas (CH4 + CO2) mixtures. Both catalytic, i.e. open-circuit, and electrocatalytic, i.e. closed-circuit, measurements were carried out. Open-circuit kinetic data showed that the rate of the catalytic reaction of the dry(CO2)-reforming of methane is maximized at about equimolar CO2/CH4 feed ratio for all temperatures studied. Closed-circuit data showed that cell output characteristics (i.e. current and power densities) are also maximized for equimolar CO2/CH4 biogas composition. Power densities up to 51.6 mW/cm2 (at V = 453 mV, i = 114 mA/cm2, T = 875 °C) have been obtained. Long-term operation experiments demonstrated that the constructed biogas fuel cell has very stable behavior for all three different simulated biogas compositions fed, including poor, equimolar and rich methane constitutions.Presented on: Solid State Ionic

“Promotion by sodium in emission control catalysis: The difference between alkanes and alkenes in the Pd-catalysed reduction of NO by hydrocarbons

Δημοσίευση σε επιστημονικό περιοδικόSummarization: The activity and selectivity of Pd catalysts supported on YSZ and dosed with different amounts of Na promoter has been investigated for the reduction of NO by alkenes (C3H6) or alkanes (CH4). It is found that Na strongly promotes the reduction of NO by C3H6. Rate increases by an order of magnitude are achievable, while the N2-selectivity is improved from ~75% over the unpromoted Pd catalyst to >95% over the optimally Na-promoted catalyst. With CH4 as the reductant, a very different behaviour is observed: for all loadings, Na induces only poisoning. The experimental data indicate that Na increases the strength of NO chemisorption relative to the hydrocarbons. This is accompanied by weakening of the N-O bond, thus facilitating NO dissociation, which is proposed as the critical reaction-initiating step. According to this model the promoting or poisoning effect of Na depends on the interaction strength of the catalyst surface with the hydrocarbon. The different behaviour of propene and methane reflects the weaker interaction of alkanes with metal surfaces compared to that of alkenes. XPS and Auger data demonstrate that Na coverage increases monotonically with promoter loading and that there is no significant tendency for the promoter to agglomerate with increasing promoter loading. However, a very small but constant tendency to accumulate subsurface or dissolved Na was observed as the promoter loading is increased.Παρουσιάστηκε στο: Global-Nest: the International Journa

The effect of sodium on the Pd-catalyzed reduction of NO by methane

Summarization: The kinetics of NO reduction by methane over Pd catalysts supported on 8 mol% yttria-stabilised zirconia (YSZ) has been studied at atmospheric pressure in the 620–770 K temperature range. Langmuir–Hinshelwood type kinetics are found with characteristic rate maxima reflecting competitive adsorption of NO and methane: NO adsorption is much more pronounced than that of methane within the temperature range of this investigation. Pd is an effective catalyst: 100% selectivity towards N2 can be achieved at 100% conversion of NO over this wide temperature range. Sodium causes strong poisoning of the reaction. The response of the system to variations in NO and methane concentrations, temperature, and sodium loading indicate that this is due to the Na-induced enhancement of NO chemisorption and dissociation relative to methane adsorption, i.e. sodium enhances oxygen poisoning of the catalyst. These results stand in revealing contrast to the strong promotional effect of sodium in the reduction of NO by propene over the same catalysts. The very different response of the two hydrocarbon reductants to Na doping of the Pd catalyst receives a consistent explanation.Presented on: Applied Catalysis B: Environmenta