Graphene as an Electron Shuttle for Silver Deoxidation: Removing a Key Barrier to Plasmonics and Metamaterials for SERS in the Visible

The role of graphene in enabling deoxidation of silver nanostructures, thereby contributing to enhance plasmonic properties and to improve the temporal stability of graphene/silver hybrids for both general plasmonic and meta‐materials applications, as well as for surface enhanced Raman scattering (SERS) substrates, is demonstrated. The chemical mechanism occurring at the graphene–silver oxide interface is based on the reduction of silver oxide triggered by graphene that acts as a shuttle of electrons and as a kind of catalyst in the deoxidation. A mechanism is formulated, combining elements of electron transfer, role of defects in graphene, and electrochemical potentials of graphene, silver, and oxygen. Therefore, the formulated model represents a step forward from the simple view of graphene as barrier to oxygen diffusion proposed so far in literature. Single layer graphene grown by chemical vapor deposition is transferred onto silver thin films, a periodic silver fishnet structure fabricated by nanoimprint lithography, and onto silver nanoparticle ensembles supporting a localized surface plasmon resonance in the visible range. Through the study of these nanostructured graphene/Ag hybrids, the effectiveness of graphene in preventing and reducing oxidation of silver plasmonic structures, keeping silver in a metallic state over months at air exposure, is demonstrated. The enhanced and stable plasmonic properties of the silver‐fishnet/graphene hybrids are evaluated through their SERS response for detecting benzyl mercaptane.     

WeNMR: Structural Biology on the Grid

The WeNMR (http://www.wenmr.eu) project is a European Union funded international effort to streamline and automate analysis of Nuclear Magnetic Resonance (NMR) and Small Angle X-Ray scattering (SAXS) imaging data for atomic and near-atomic resolution molecular structures. Conventional calculation of structure requires the use of various software packages, considerable user expertise and ample computational resources. To facilitate the use of NMR spectroscopy and SAXS in life sciences the WeNMR consortium has established standard computational workflows and services through easy-to-use web interfaces, while still retaining sufficient flexibility to handle more specific requests. Thus far, a number of programs often used in structural biology have been made available through application portals. The implementation of these services, in particular the distribution of calculations to a Grid computing infrastructure, involves a novel mechanism for submission and handling of jobs that is independent of the type of job being run. With over 450 registered users (September 2012), WeNMR is currently the largest Virtual Organization (VO) in life sciences. With its large and worldwide user community, WeNMR has become the first Virtual Research Community officially recognized by the European Grid Infrastructure (EGI).     

Probing small network differences in sulfur‐cured rubber compounds by combining nuclear magnetic resonance and swelling methods

We studied the network structure of elastomers based on polyisoprene, polybutadiene, and their blends in the narrow range of formulations compatible with actual use in the automotive tyre industry. Cross‐link density (CLD) was quantified comparatively by low‐field ¹H multiple quantum time domain nuclear magnetic resonance (MQ TD‐NMR) and by equilibrium swelling technique. The robustness and agreement of the two methods was demonstrated in measuring minute alterations of unfilled vulcanizates beyond the optimum cure time. Comparison with samples where polysulfidic bonds were selectively cleaved also demonstrates that the length of the sulfur chain constituting the cross‐link does not significantly affect residual dipolar coupling. Kraus, Lorenz, and Parks correction for filler restriction on swelling is validated by MQ TD‐NMR, which also allows extracting information on cross‐link distribution not provided by swelling measurement. Cross‐link distributions in the blends were demonstrated to be significantly different from the weighted average of the pure samples, while average proton–proton residual dipolar coupling values correspond. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42700.     

Data assimilation impact of in situ and remote sensing meteorological observations on wind power forecasts during the first Wind Forecast Improvement Project (WFIP)

During the first Wind Forecast Improvement Project (WFIP), new meteorological observations were collected from a large suite of instruments, including wind velocities measured on networks of tall towers provided by wind industry partners, wind speeds measured by cup anemometers mounted on the nacelles of wind turbines, and wind profiles by networks of Doppler sodars and radar wind profilers. Previous data denial studies found a significant improvement of up to 6% root mean squared error (RMSE) reduction for short‐term wind power forecasts due to the assimilation of all of these observations into the National Oceanic and Atmospheric Administration (NOAA) Rapid Refresh (RAP) forecast model using a 3D variational data assimilation scheme. As a follow‐on study, we now investigate the impacts of assimilating into the RAP model either the additional remote sensing observations (sodars and radar wind profilers) alone or assimilating the industry‐provided in situ observations (tall towers and nacelle anemometers) alone, in addition to routinely available standard meteorological data sets. The more numerous tall tower/nacelle observations provide a relatively large improvement through the first 3 to 4 hours of the forecasts, which diminishes to a negligible impact by forecast hour 6. In comparison, the sparser vertical profiling sodars/radars provide an initially smaller impact that decays at a much slower rate, with a positive impact present through the first 12 hours of the forecast. Large positive assimilation impacts for both sets of instruments are found during daytime hours, while small or even negative impacts are found during nighttime hours.     

Understanding consumption choice of prosecco wine: an empirical analysis using Italian and German Homescan data

This study analyses the degree to which wine consumers are truly able to intrinsically evaluate the meaning of a designation of origin certification or whether they generally consider such a certification to be a vague credence attribute. This issue was addressed through an empirical analysis of Homescan Panel data in the Italian and German markets, using a Heckman probit model to assess the role of consumers’ characteristics and habits in the choice of ‘Prosecco’ wines characterized by two different levels of the denomination of origin certification. Our results suggest that Prosecco sparkling wine is perceived as a product of medium-high positioning and is preferably purchased by households that buy wines with a higher unit price. In contrast, consumers who appreciate sparkling wine did not show any preference towards a specific type of Prosecco, especially outside the area of production, such as in the German market, which suggests that they still do not completely understand the difference between the certification levels.     

Architecture,values and perception: Between rhetoric and reality

Throughout history, design values have always underlined a given architectural style. The manner architects and architectural critics distinguish between them varies from that of the public. In fact a style well perceived by civil society was read as pathological by architectural academia. This paper examines the values and perceptions of contemporary architecture by architects and civil society. Through qualitative methodology, a project by each of the following leading contemporary architects-Renzo Piano, Norman Foster and Rem Koolhaas-was analyzed. The selected designs, all commissioned not more than a decade ago, vary in locations from Malta to Lebanon to India. The study concludes that design values and perceptions of architecture as read by members of the architectural profession do not tally with those of the public. The emphasis by architects is on the aesthetic whilst non-architects focus on the utilitarian dimension. Furthermore, the rhetorical language which architects use is not read as such by the public. The assessment of the public is based on the existential reality which they experience. The perception of civil society matters; it is at the core of architectural design values.     

Si-substituted hydroxyapatite nanopowders: Synthesis, thermal stability and sinterability

Synthetic hydroxyapatites incorporating small amounts of Si have shown improved biological performances in terms of enhanced bone apposition, bone in-growth and cell-mediated degradation.This paper reports a systematic investigation on Si-substituted hydroxyapatite (Si 1.40 wt%) nanopowders produced following two different conventional wet methodologies: (a) precipitation of Ca(NO₃)₂·4H₂O and (b) titration of Ca(OH)₂. The influence of the synthesis process on composition, thermal behaviour and sinterability of the resulting nanopowders is studied.Samples were characterised by electron microscopy, induced coupled plasma atomic emission spectroscopy, thermal analysis, infrared spectroscopy, N₂ adsorption measurements, X-ray diffraction and dilatometry. Semicrystalline Si-substituted hydroxyapatite powders made up of needle-like nanoparticles were obtained, the specific surface area ranged between 84 and 110 m²/g. Pure and Si-substituted hydroxyapatite nanopowders derived from Ca(NO₃)₂·4H₂O decomposed around 1000 °C. Si-substituted hydroxyapatite nanopowders obtained from Ca(OH)₂ were thermally stable up to 1200 °C and showed a distinct decreased thermal stability with respect to the homologous pure sample. Si-substituted hydroxyapatites exhibited higher sintering temperature and increased total shrinkage with respect to pure powders. Nanostructured dense ceramics were obtained by sintering at 1100 °C Si-substituted hydroxyapatites derived from Ca(OH)₂.