Electronic excitation of the methyl methacrylate and styrene molecules in the vuv range

Angle-resolved electron energy-loss spectra have been measured for the methyl methacrylate (MMA) and styrene molecules in the 0 - 50 eV energy range. The spectra have been obtained at 1 keV incident energy, with an energy resolution of 0.8 eV and covering an angular range of 2.0 to 7.0 degrees. Within our knowledge, this is the first gas-phase excitation spectrum for MMA and styrene in this energy range. The spectra of MMA at small scattering angles are dominated by an intense peak at 6.7 eV followed by a broad band centered at about 16 eV. In the case of styrene, six bands can be observed in the spectra. Based on the angular behaviour of the excitation spectra of these molecules, the low-lying peaks observed are considered to be associated predominantly with dipole-allowed processes. In both cases, new bands can be observed for excitation energies greater than 20 eV. This could be associated with dipole-forbidden transitions to shake-up and doubly-excited states.

Seismic assessment of a heavy-timber frame structure with ring-doweled moment-resisting connections

The performance of heavy-timber structures in earthquakes depends strongly on the inelastic behavior of the mechanical connections. Nevertheless, the nonlinear behavior of timber structures is only considered in the design phase indirectly through the use of an R-factor or a q-factor, which reduces the seismic elastic response spectrum. To improve the estimation of this, the seismic performance of a three-story building designed with ring-doweled moment resisting connections is analyzed here. Connections and members were designed to fulfill the seismic detailing requirements present in Eurocode 5 and Eurocode 8 for high ductility class structures. The performance of the structure is evaluated through a probabilistic approach, which accounts for uncertainties in mechanical properties of members and connections. Nonlinear static analyses and multi-record incremental dynamic analyses were performed to characterize the q-factor and develop fragility curves for different damage levels. The results indicate that the detailing requirements of Eurocode 5 and Eurocode 8 are sufficient to achieve the required performance, even though they also indicate that these requirements may be optimized to achieve more cost-effective connections and members. From the obtained fragility curves, it was verified that neglecting modeling uncertainties may lead to overestimation of the collapse capacity

La patrimonialit\ue0 del monastero di S. Silvestro di Nonantola tra alto e basso Medioevo (con alcuni spunti sulla sua presenza nell'Italia centrale e nelle Marche)

Caratteri, morfologie ed evoluzione della patrimonialit\ue0 del monastero di S. Silvestro di Nonantola dalle origini alla Commenda, con particolare riguardo al sistema di produzione, agli assetti insediativi e al rapporto tra cenobio e mondo contadino

Serendipit\ue0 e ricerca storica. Nuovi dati sulla pieve di Quarantoli, sulla Falconiera e su Don Felice Ceretti

Da un registro dei banchi della pieve di Quarantoli notizie ulteriori sulla chiesa e sul territori

Gestione e misurazione dell'acqua nell'alto Medioevo

Disponibilit\ue0 e distribuzione dell'acqua; misurazione della lunghezza e profondit\ue0 dei corsi d'acqua; maree; navigabilit\ue0 e navigazione; trionfo delle microstrutture; isole fluviali; tempi di navigazione; l'oro dei fiumi; pozzi e cisterne; terme e bagni