Bioavailability and biological effect of engineered silver nanoparticles in a forest soil.

The extensive use of silver nanoparticles (SNPs) as antimicrobial in food, clothing and medicine, leads inevitably to a loss of such nanomaterial in soil and water. Little is known about the effects of soil contamination, in particular, on microbial cells, which play a fundamental ecological role. In this work, the impact of SNPs on forest soil has been studied, investigating eco-physiological indicators of microbial biomass and microbial diversity with culture-dependent and independent techniques. Moreover, SNPs bioavailability and uptake were assessed. Soil samples were spiked with SNPs at two different concentrations (10 and 100 µg g(-1)dw) and incubated with the relative controls for 30, 60 and 90 days. The overall parameters showed a significant influence of the SNPs on the soil microbial community, revealing a marked shift after 60 days of incubation.

The bright optical flash and afterglow from the gamma-ray burst GRB 130427A.

The optical light generated simultaneously with x-rays and gamma rays during a gamma-ray burst (GRB) provides clues about the nature of the explosions that occur as massive stars collapse. We report on the bright optical flash and fading afterglow from powerful burst GRB 130427A. The optical and >100-megaelectron volt (MeV) gamma-ray flux show a close correlation during the first 7000 seconds, which is best explained by reverse shock emission cogenerated in the relativistic burst ejecta as it collides with surrounding material. At later times, optical observations show the emergence of emission generated by a forward shock traversing the circumburst environment. The link between optical afterglow and >100-MeV emission suggests that nearby early peaked afterglows will be the best candidates for studying gamma-ray emission at energies ranging from gigaelectron volts to teraelectron volts.

[Plant protection products: new tools for exposure and risk assessment in agriculture]. / Antiparassitari: nuovi strumenti per la valutazione dell'esposizione del rischio in ambito agricolo.

Our experience in assessment and management of chemical risk in agriculture consists of three lines: i) definition and modeling of the relationships between different exposure determinants to create the possibility of doing risk assessment without measurements ii) identification, from the Acceptable Operator Exposure Levels (AOEL), of provisional biological exposure indices for pesticides; iii) identification of analytical approaches adequate for the production of the measures needed to support the above mentioned activities starting from the use of multi-residue methods, allowing the determination in one run of several active ingredients and metabolites.

[Physically-based model of pesticide application for risk assessment of agricultural workers]. / Valutazione del rischio nell'applicazione in campo di prodotti fitosanitari attraverso modelli a base fisica per la stima dell'esposizione.

Due to their unavoidable toxicity to non-target organisms, including man, the not of Plant Protection Products requires a thorough risk assessment to rationally advise safe use procedures and protection equipment by farmers. Most information on active substances and formulations, such as dermal absorption rates and exposure limits are available in the large body of regulatory data. Physically-based computational models can be used to forecast risk in real-life conditions (preventive assessment by 'exposure profiles'), to drive the cost-effective use of products and equipment and to understand the sources of unexpected exposure.