Synthesis, morphology and compositional evolution of silicon nanowires directly grown on SnO(2) substrates

We here propose an all-in situ method for growing vapor-liquid-solid (VLS) silicon nanowires (SiNWs) directly on SnO(2) substrates in a plasma-enhanced chemical vapor deposition system. The tin catalysts are formed by a well-controlled H(2) plasma treatment of the SnO(2) layer. The lowest temperature for the tin-catalyzed VLS SiNWs growth in a silane plasma is ～250?°C. The effects of substrate temperature and H(2) dilution of silane on the morphology and compositional evolution of the SiNWs were systematically investigated. The catalyst content in the SiNWs can be effectively controlled by the deposition temperature. Moreover, enhanced absorption (down to ～1.1?eV) is achieved due to the strong light trapping and anti-reflection effects in the straight and long tapered SiNWs.     

Peri-urban agriculture in Barcelona: outlining landscape dynamics vis à vis socio-environmental functions

Dispersed urbanisation promotes complex relationships between rural areas and the urban fringe, with emerging new functions for peri-urban agriculture (PUA). Although PUA is a type of productive farming of interest for urban planning due to its recognised functions, comparative analyses are needed to relate farm dynamics to fringe landscape modifications in different socio-economic contexts. Given the current limitation of specific methodologies to analyse PUA dynamics, a quantitative approach profiling farm types and the related landscape structure in an expanding urban region, the Metropolitan Area of Barcelona, is proposed. Results indicate that PUA is based on five typologies with different territorial values, as a consequence of diverse economic relevance, socio-environmental weight and landscape prominence. Based on these results, a conservation strategy aimed at preserving the residual PUA landscape is proposed through the promotion of a polycentric functional network of farming with natural vegetation.     

The effect of high pressure and residual oxygen on the color stability of minced cured restructured ham at different levels of drying,pH, and NaCl

Color stability of minced cured restructured ham was studied by considering the effects of high pressure (HP) (600 MPa, 13 °C, 5 min), raw meat pH₂₄ (low, normal, high), salt content (15, 30 g/kg), drying (20%, 50% weight loss), and residual oxygen level (0.02%–0.30%). Raw hams were selected by pH₂₄ in Semimembranosus, mixed with additives, frozen, sliced, and dried by the Quick-Dry-Slice® (QDS) process followed by HP treatment or not (control). Packaging and storage simulated industrial packaging: modified atmosphere containing 80% N₂, 20% CO₂, and residual O₂ in one of three intervals: < 0.1%, 0.1%–0.2%, or 0.2%–0.3%, and retail storage conditions: chill storage, 12 h light, 12 h darkness. HP improved the stability of the redness of 20% QDS hams, while the stabilizing effect on 50% QDS hams was smaller, concluding that water has the dominating role. Raw meat pH₂₄, salt content, and residual oxygen level had varying effects on the stability of the red color.     

NIR technology for on-line determination of superficial a(w) and moisture content during the drying process of fermented sausages

Three different NIR equipment were evaluated based on their ability to predict superficial water activity (a(w)) and moisture content in two types of fermented sausages (with and without moulds on surface), using partial least squares (PLS) regression models. The instruments differed mainly in wavelength range, resolution and measurement configuration. The most accurate equipment was used in a new experiment to achieve robust models in sausages with different salt contents and submitted to different drying conditions. The models developed showed determination coefficients (R(2)(P)) values of 0.990, 0.910 and 0.984, and RMSEP values of 1.560%, 0.220% and 0.007% for moisture, salt and a(w) respectively. It was demonstrated that NIR spectroscopy could be a suitable non-destructive method for on-line monitoring and control of the drying process in fermented sausages.     

Investigation of char strength and expansion properties of an intumescent coating exposed to rapid heating rates

An efficient and space saving method for passive fire protection is the use of intumescent coatings, which swell when exposed to heat, forming an insulating char layer on top of the virgin coating. Although the temperature curves related to so-called cellulosic fires are often referred to as slow heating curves, special cases where the protective char is mechanically damaged and partly removed can cause extremely fast heating of the coating. This situation, for a solvent based intumescent coating, is simulated using direct insertion of free films into a muffle oven. The char formed is evaluated with respect to the mechanical resistance against compression, degree of expansion, and residual mass fraction. Experimental results show that when using this type of shock heating, the mechanical resistance of the char against compression cannot meaningfully be correlated to the expansion factor. In addition, char properties, measured at room temperature, were dependent on the preceding storage conditions (in air or in a desiccator). The char was found to have the highest mechanical strength against compression in the outer crust facing the heat source. For thin (147 μm) free coating films, a tendency to contract in the horizontal plane was observed. The experimental approach is relevant for testing of intumescent coatings used in buildings where moving or falling objects may damage the char during a fire.     

A Kerberized Architecture for Fast Re-authentication in Heterogeneous Wireless Networks

In this paper we present an architecture for fast re-authentication, based on the use of the Kerberos protocol, which allows the reduction in the latency introduced for an authentication process based on the Extensible Authentication Protocol (EAP) when providing network access in mobile networks. The architecture supports two modes of operation, proactive and reactive, to reduce the latency added for the authentication processes which is required when a mobile user changes network points of attachment. Moreover, we provide implementation details on a representative wireless testbed and obtain experimental results from the testbed. Those results are used for simulations to evaluate the performance of the proposed architecture for different deployment scenarios and parameters. We also provide a mathematical analysis to compute authentication delay and validate the simulation results. Performance comparison based on the experiment, simulation and analysis show that the proposed architecture can reduce the authentication delay, compared to other alternatives in typical deployment scenarios.     

Development of Pd-based membranes as hydrogen diffusion anodes

Pd-based membranes have been prepared by Pd electroless deposition on porous stainless steel substrate and their structure, composition, morphology and thickness were analyzed by X-ray diffraction (XRD), EDS and scanning electronic microscopy (SEM). The performance of these membranes as hydrogen diffusion electrodes was evaluated in a three-electrode cell in alkaline medium. The activity towards hydrogen oxidation was high at the beginning of the experiment, but it significantly decreased with time. The major cause of this phenomenon has been attributed to the slow entry of hydrogen at the H₂/Pd interface. Even so, the technical feasibility of using these membranes as gas diffusion electrodes (GDE) has been proven.     

Blocking versus robustness in industrial contexts

The paper discusses the similarities and differences between blocking factors (blocked designs) and noise factors (robust designs) in industrial two‐level factorial experiments. The discussion covers from the objectives of both design types and the nature of blocking and noise factors to the types of designs and the assumptions needed in each case. The conclusions are as follows: the nature and characteristics of noise and blocking factors are equal or very similar; the designs used in both situations are also similar; and the main differences lie in the assumptions and the objectives. The paper argues that the objectives are not in conflict and can easily be harmonized. In consequence, we argue in favor of a unified approach that would clarify the issue, especially for students and practitioners.