Thermal Induced Polymerization of l-Lysine forms Branched Particles with Blue Fluorescence

AbstractThe polycondensation of amino acids can originate complex polymers that display fascinating structural and optical properties. Thermally induced amidation of l‐lysine allows forming a branched polymer without the support of any catalyst. The polycondensation is completed at 240–250 °C; at higher temperatures, the amino acid degrades. The obtained polylysine particles have been studied by transmission electron microscopy (TEM), nuclear magnetic resonance, and infrared spectroscopy that allow for investigating the different steps of the synthesis. The resulting structure is characterized by peculiar optical properties, e.g., excitation‐dependent blue fluorescence and good quantum efficiency. Hydrogen bonds and the interactions of the amino acids are considered responsible for the optical properties of both l‐lysine monomer solutions at high concentrations and the branched nanopolymers

Assessment of origin and fate of contaminants along mining-affected Rio Montevecchio (SW Sardinia, Italy): A hydrologic-tracer and environmental mineralogy study

Hydrologic tracer techniques were applied to Rio Montevecchio (SW Sardinia, Italy), a stream affected by mine drainage, allowing the calculation of discharge and contaminant loads. Discharge along the stream showed a constant increase throughout the 2.7 km-long study reach, up to 13.6 l/s at the last synoptic point. Calculated loads of mine-related constituents were large, reaching values of 1780 kg/day for, 340 kg/day for Zn, 47 kg/day for Fe, and 50 kg/day for Mn. The difference of the cumulative instream metal loads between the first and the last synoptic sampling points indicated gains of 421 kg/day for Zn, 2080 kg/day for, 56 kg/day for Mn, and 50 kg/day for Fe. The source areas critical for contaminants loading were almost all concentrated in the first 800 meters of the stream, with the exception of Pb, whose loading occurs evenly along the whole study reach. Precipitation of secondary minerals along the streambed was responsible for a very high attenuation of Al and Fe loads (66% and 77%) and affected also and Zn loads, though less effectively. Rio Montevecchio has the second highest metal load among the rivers investigated with tracer techniques in SW Sardinia. In comparison with Rio Irvi, which has one order of magnitude higher metal loads, natural attenuation processes limit the loads in Rio Montevecchio. Results are useful to clarify the hydrogeochemical paths involved in the release and attenuation of pollutants, improving our understanding of stream responses to contamination and aiding development of site-specific remediation actions