Near-infrared modulation by means of GeTe/SOI-based metamaterial.

Today, nanophotonics still lacks components for modulation that can be easily implementable in existing silicon-on-insulator (SOI) technology. Chalcogenide phase change materials (PCMs) are promising candidates for tuning in the near infrared: at the nanoscale, thin layers can provide enough contrast to control the optical response of a nanostructure. Moreover, all-dielectric metamaterials allow for resonant behavior without having ohmic losses in the telecom range. Here, a novel hybridization of a SOI-based metamaterial with PCM GeTe is experimentally investigated. A metamaterial based on Si nanorods, covered by a thin layer of GeTe, is designed and fabricated. Switching GeTe from amorphous to crystalline leads to a rather high resonance-governed reflection contrast at 1.55 µm. Additional confocal Raman imaging is done to differentiate the crystallized zones of the metamaterials' unit cell. The findings are in good agreement with numerical analysis and show good perspectives of all-dielectric tunable near-infrared nanophotonics.

Bioactivity of humic substances and water extracts from compost made by ligno-cellulose wastes from biorefinery.

The ligno-cellulose residues from biorefinery production of bio-ethanol were used as woody structuring material within an on-farm composting system, with the aim to obtain bioactive water soluble and humic fractions from composted materials. The molecular characterization of initial biomasses and final products revealed a transformation towards more stable compounds during composting and showed the selective incorporation of specific phenolic derivatives of ligno-cellulose in both bulk samples and corresponding extracts. While the use of the stable bulk composts as organic fertilizer resulted in a decrease of nitrogen and phosphorous assimilation in maize tissues, a bio-stimulation was shown by water soluble organic compounds and humic substances in germination tests and pot experiments, respectively. The differential responses obtained in maize seedlings and plants were related to the molecular composition and concentration of the applied water extracts and humic substances, thus suggesting a role of phenols and lignin derivatives in the stimulation of maize roots and shoots and the enhancement of P uptake. The results confirm that ligno-cellulose residues may be effectively recycled as composting additives in order to enrich mature compost in aromatic and lignin compounds. A preliminary knowledge on the molecular characteristics and biological properties of composted materials is an essential requirement to select the most suitable derivatives from composted ligno-cellulose wastes in sustainable agricultural practices.

Plant tolerance to mercury in a contaminated soil is enhanced by the combined effects of humic matter addition and inoculation with arbuscular mycorrhizal fungi.

In a greenhouse pot experiment, lettuce plants (Lactuca sativa L.) were grown in a Hg-contaminated sandy soil with and without inoculation with arbuscular mycorrhizal fungi (AMF) (a commercial inoculum containing infective propagules of Rhizophagus irregularis and Funneliformis mosseae) amended with different rates of a humic acid (0, 1, and 2 g kg(-1) of soil), with the objective of verifying the synergistic effects of the two soil treatments on the Hg tolerance of lettuce plants. Our results indicated that the plant biomass was significantly increased by the combined effect of AMF and humic acid treatments. Addition of humic matter to soil boosted the AMF effect on improving the nutritional plant status, enhancing the pigment content in plant leaves, and inhibiting both Hg uptake and Hg translocation from the roots to the shoots. This was attributed not only to the Hg immobilization by stable complexes with HA and with extraradical mycorrhizal mycelium in soil and root surfaces but also to an improved mineral nutrition promoted by AMF. This work indicates that the combined use of AMF and humic acids may become a useful practice in Hg-contaminated soils to reduce Hg toxicity to crops.

[Air pollution and daily mortality in Turin, 1991-1996]. / Inquinamento atmosferico e mortalità giornaliera a Torino, 1991-1996.

A time series study was carried out to assess the relationship between the air pollutants measured by the air quality monitoring network and daily mortality in Turin, Italy. We used TSP, SO2, NO2, O3, and CO concentrations measured from 1-1-1991 to 31-12-1996 at three stations of the city network, chosen to represent different, typical circumstances of exposure to air pollution in the town. The analysis was performed by robust Poisson regression model including loss smoothing functions to allow for long-time trend, seasons, temperature and relative humidity. Dummy variables for the days of the week and holidays were also included. The relative risk of death for a unit increase in the pollutant concentration either during the same day (lag 0) in the previous ones (lag up to 5) was computed. The unit increase was 50 micrograms/m3 for TSP, SO2, NO2, O3, and 2 mg/m3 for CO. The average daily number of deaths for natural causes was 21. The relative risks for total mortality were 1.04 for TSP (lag 1), 1.10 for SO2 (lag 2), 1.06 for NO2 (lag 1), 1.01 for O3 (lag 0), 1.03 for CO (lag 1). The relative risks were 1.05 for TSP (lag 0), 1.12 for SO2 (lag 2), 1.07 for NO2 (lag 1), 1.03 for O3 (lag 0), 1.03 for CO (lag 1) for cardiovascular mortality, and 1.08 for TSP (lag 2), 1.20 for SO2 (lag 2), 1.12 for NO2 (lag 2), 1.03 for O3 (lag 2), 1.05 for CO (lag 2) for respiratory mortality.