Hydrogen induced optically-active defects in silicon photonic nanocavities

This work was supported by Era-NET NanoSci LECSIN project coordinated by F. Priolo, by the Italian Ministry of University and Research, FIRB contract No. RBAP06L4S5 and by the EPSRC UKSp project. Partial financial support by the Norwegian Research Council is also acknowledged.We demonstrate intense room temperature photoluminescence (PL) from optically active hydrogen- related defects incorporated into crystalline silicon. Hydrogen was incorporated into the device layer of a silicon on insulator (SOI) wafer by two methods: hydrogen plasma treatment and ion implantation. The room temperature PL spectra show two broad PL bands centered at 1300 and 1500 nm wavelengths: the first one relates to implanted defects while the other band mainly relates to the plasma treatment. Structural characterization reveals the presence of nanometric platelets and bubbles and we attribute different features of the emission spectrum to the presence of these different kind of defects. The emission is further enhanced by introducing defects into photonic crystal (PhC) nanocavities. Transmission electron microscopy analyses revealed that the isotropicity of plasma treatment causes the formation of a higher defects density around the whole cavity compared to the ion implantation technique, while ion implantation creates a lower density of defects embedded in the Si layer, resulting in a higher PL enhancement. These results further increase the understanding of the nature of optically active hydrogen defects and their relation with the observed photoluminescence, which will ultimately lead to the development of intense and tunable crystalline silicon light sources at room temperature.Publisher PDFPeer reviewe

The role of digital technologies in supporting the implementation of circular economy practices by industrial small and medium enterprises

The adoption of Industry 4.0's digital technologies can enable the implementation of circular economy practices. Nonetheless, current indications for industrial practitioners on how to exploit the broad set of technologies for circular transition appear unclear. This issue is even more challenging for small and medium enterprises, which are typically endowed with more limited resources than larger firms and are characterised by both a digital and circular divide. This present study contributes to the academic debate by offering an exploratory empirical analysis-based on semi-structured interviews-that involved 10 Italian industrial small and medium enterprises to deepen the knowledge of the supporting role played by digital technologies in implementing circular economy practices by small and medium enterprises, also considering the potential synergies among such technologies. Results are of interest also to industrial decision-makers, allowing them to exploit their firms' resources towards the adoption of those digital technologies that could be more effective to foster the circular transition

Approaching the seismogenic source of the Calabria 8 September 1905 earthquake: New geophysical, geological and biochemical data from the S. Eufemia Gulf (S Italy)

Recognizing the seismogenic source of major historical earthquakes, particularly when these have occurred offshore, is a long-standing issue across the Mediterranean Sea and elsewhere. The destructive earthquake (M ~7) that struck western Calabria (southern Italy) on the night of 8 September 1905 is one such case. having various authors proposed a seismogenic source, with apparently diverse hypotheses and without achieving a unique solution. To gain novel insight into the crustal volume where the 1905 earthquake took place and to seek a more robust solution for the seismogenic source associated with this destructive event, we carried out a well-targeted multidisciplinary survey within the Gulf of S. Eufemia (SE Tyrrhenian Sea), collecting geophysical data, oceanographic measurements, and biological, chemical and sedimentary samples. We identified three main tectonic features affecting the sedimentary basin in the Gulf of S. Eufemia: 1) a NE-SW striking, ca. 13-km-long, normal fault, here named S. Eufemia Fault; 2) a WNW-striking polyphased fault system; and 3) a likely E-W trending lineament. Among these, the normal fault shows evidence of activity witnessed by the deformed recent sediments and by its seabed rupture along which, locally, fluid leakage occurs. Features in agreement with the anomalous distribution of prokaryotic abundance and biopolymeric C content, resulted from the shallow sediments analyses. The numerous seismogenic sources proposed in the literature during the past 15 years make up a composite framework of this sector of western Calabria, that we tested against a) the geological evidence from the newly acquired dataset, and b) the regional seismotectonic models. Such assessment allows us to propose the NE-SW striking normal fault as the most probable candidate for the seismogenic source of the 1905 earthquake. Re-appraising a major historical earthquake as the 1905 one enhances the seismotectonic picture of western Calabria. Further understanding of the region and better constraining the location of the seismogenic source may be attained through integrated interpretation of our data together with a) on-land field evidence, and b) seismological modeling

Evolution of infectious bronchitis virus in the field after homologous vaccination introduction

International audienceAbstractDespite the fact that vaccine resistance has been typically considered a rare phenomenon, some episodes of vaccine failure have been reported with increasing frequency in intensively-raised livestock. Infectious bronchitis virus (IBV) is a widespread avian coronavirus, whose control relies mainly on extensive vaccine administration. Unfortunately, the continuous emergence of new vaccine-immunity escaping variants prompts the development of new vaccines. In the present work, a molecular epidemiology study was performed to evaluate the potential role of homologous vaccination in driving IBV evolution. This was undertaken by assessing IBV viral RNA sequences from the ORF encoding the S1 portion of viral surface glycoprotein (S) before and after the introduction of a new live vaccine on broiler farms in northern-Italy. The results of several biostatistics analyses consistently demonstrate the presence of a higher pressure in the post-vaccination period. Natural selection was detected essentially on sites located on the protein surface, within or nearby domains involved in viral attachment or related functions. This evidence strongly supports the action of vaccine-induced immunity in conditioning viral evolution, potentially leading to the emergence of new vaccine-escape variants. The great plasticity of rapidly-evolving RNA-viruses in response to human intervention, which extends beyond the poultry industry, is demonstrated, claiming further attention due to their relevance for animal and especially human health

Interactions between free-living nematodes and benthic diatoms: insights from the Gulf of Trieste (northern Adriatic Sea)

From July 2010 to July 2012, free-living nematodes were investigated in terms of abundance, genera and trophic composition at the long term St. C1 (depth 18 m), located in the Gulf of Trieste (northern Adriatic Sea). The integration of these results with environmental (e.g. sediment grain-size, Biopolymeric C and Chl a) and biological variables (benthic diatom biomass and composition) collected synoptically with nematodes, allowed to clarify the linkage between these organisms and another ecosystem component, i.e. benthic diatoms. The observed peaks of nematode abundance in summer samplings were ascribable almost exclusively to piercing nematodes that feed on microalgae (Chromadoridae and, among them, Ptycholaimellus) and were concomitant with the highest numbers of benthic diatoms. DISTLM outputs further corroborated this interaction by indicating Chl a, i.e. a proxy of benthic diatoms, as the only environmental variable that significantly shaped nematode assemblage over the 2-year period. This linkage was not explained only quantitatively (i.e. more diatoms supported more nematodes) but also qualitatively. During winter, in fact, the presence of heavily silicified diatoms co-occurred with nematode minima and the lowest percentage of piercing organisms, suggesting an overall minor ability of the assemblage in using this feeding strategy. In a benthic ecosystem functioning point of view, the observed seasonal pattern of variation in both nematodes and benthic diatoms suggests that more of the energy flowing to nematodes during the summer derives directly from benthic diatom primary production while in the winter this linkage is less important.</div