A semi-covalent imprinted polymer was prepared by precipitation polymerisation using propazine methacrylate as template molecule, ethylene glycol dimethacrylate as cross-linker and toluene as ...porogen. After removal of propazine by basic hydrolysis of the covalent bond, the optimum loading, washing and elution conditions for the solid-phase extraction of the selected triazines were established. The binding sites present in the polymeric matrix were characterised by fitting the experimental results of several rebinding studies to the Langmuir–Freundlich isotherm. Subsequently, an analytical methodology based on molecularly imprinted solid-phase extraction (MISPE) was developed for the determination of several triazinic herbicides in soil and vegetable samples. Following this procedure, a good degree of clean-up of the sample extracts was easily achieved, allowing the HPLC-UV determination of selected triazines in complex samples at low concentration levels.
The occupation of the Iberian Peninsula during the Upper Palaeolithic is mainly known from archaeological sites located in the Cantabrian and Mediterranean regions. Numerous sites have been excavated ...in these two regions when few sites are found in the interior of the peninsula. Several authors explain this scarcity of sites, in the inner region during the Upper Palaeolithic, by a decrease of human population resulting from a low capacity of human groups to adapt to the cold conditions of the Marine Isotopic Stage 2 (MIS 2), i.e. the effect of cold climate on human populations might have been stronger in the interior of the peninsula than in coastal areas. Recent studies underline the evidence of prehistoric occupation during this period in that region. It has been suggested that these occupations are isolated events limited to the warmest phases of the end of the MIS 2. The present study focuses on zooarchaeological and taphonomic aspects of the Magdalenian site of La Peña de Estebanvela (Segovia, Spain). Our results show that this site was recurrently occupied during the Magdalenian period, including warm and cold phases, which provide a new evidence of sustainable presence of human populations in the interior of the Iberian Peninsula at the end of the Upper Palaeolithic. We further propose hypotheses on the subsistence strategies (e.g. availability of hunting resources) developed at La Peña de Estebanvela and in a larger context including other Magdalenian sites of the inner region of the Peninsula.
An investigation of the structural, magnetic and electronic properties of ≈ 3 nm thick Mn5Ge3 films epitaxially grown on a Ge(1 1 1)-c(2 × 8) reconstructed surface is reported. High resolution ...transmission electron microscopy and selected area electron diffraction give evidence of 2.2% in-plane compressive strain between the Mn5Ge3 film and the Ge substrate. Magnetooptical Kerr effect measurements show that the films are ferromagnetic with a Curie temperature of ≈ 325 K. The analysis of Ge 3d core level photoelectron spectra of the Mn5Ge3 films allows determining an upper limit of 76 meV for the Ge 3d5/2 core-hole lifetime broadening. The Ge 3d3/2 core-hole lifetime broadening is found to be 15 meV larger than that of the Ge 3d5/2 core hole, because of the existence of a Coster–Kronig decay channel due to the metallic character of Mn5Ge3.
A new and sensitive methodology based on normal phase HPLC has been developed for the speciation of nickel in low-complexity plant extracts. The method combines a silica stationary phase column, a ...9:1 (v/v) hexane:ethanol mixture as mobile phase, and the detection of nickel complexes by either UV or MS. The developed methodology was applied to the speciation of nickel complexes in the cytoplasm of pea root nodules. Results obtained indicate that nickel citrate and nickel malate accounts for 99% of nickel present in pea nodule cytoplasm fraction. The low detection limit of the method (<0.2
nM) enables nickel speciation in non-hyperaccumulator plants.
PDF
