Analytical characterization of bioactive fluoropolymer ultra-thin coatings modified by copper nanoparticles

Copper–fluoropolymer (Cu-CFx) nano-composite films are deposited by dual ion-beam sputtering. The extensive analytical characterization of these layers reveals that inorganic nanoparticles composed of Cu(II) species are evenly dispersed in a branched fluoropolymer matrix. In particular, X-ray photoelectron spectroscopy has been employed to study the surface chemical composition of the material and to assess how it changes on increasing the copper loading in the composite. Transmission electron microscopy reveals that the copper nanoclusters have a mean diameter of 2–3 nm and are homogeneously in-plane distributed in the composite films. Electrothermal atomic absorption spectroscopy has been used to study the kinetics of copper release in the solutions employed for the biological tests. The Cu-CFx layers are employed as bioactive coatings capable of inhibiting the growth of target microorganisms such as Saccharomyces cerevisiae, Escherichia coli, Staphylococcus aureus, and Lysteria. The results of the analytical characterization enable a strict correlation to be established among the chemical composition of the material surface, the concentration of copper dissolved in the microorganisms broths, and the bioactivity of the nano-structured layer.     

Geodetic VLBI data analysis using VLBI3 software

Summary VLBI (Very Long Baseline Interferometry) geodetic data have been analysed. Baseline, lengths of several thousands kilometers and their time rates have been estimated from a subset of data, spanning three years, of the IRIS project and using VLBI3 software. A weighted-least-squares estimation has been carried out with thea priori standard deviations of the data modified to account for systematic biases due to mismodelling of the clocks and atmosphere. Comparisons with independent analysis show an agreement to the cm level or better both in baseline lengths and rates.     

DYNGA: a general purpose QM-MM-MD program. I. Application to water

We present a general purpose QM-MM-MD engine (DYNGA) designed to test alternative hybrid Hamiltonians geared towards the treatment of problems of interest in structural biology including the use of experimental data constraints. In this first presentation we use DYNGA to explore the behaviour of a traditional QM-MM approach in the treatment of the water—water interaction. We find the potential energy hypersurface for the water dimer computed with the HF 4–31G*/TIP3P hybrid Hamiltonian tends to be too flat. We also explore the effect of using traditional QM-MM techniques on proton wires and conclude there is a need for improvement, possibly addressed by using polarizable force fields.     

PAST AND FUTURE MANAGEMENT OF A COLLAPSED FISHERY: THE BAY OF BISCAY ANCHOVY

Abstract We analyze the efficiency of the international management of the Bay of Biscay anchovy. While a sharing agreement between France and Spain has been in place since 1992, the fish stock collapsed in 2005 and the fishery closed from 2005 to spring 2010. We consider differences in production technologies between both countries and calibrate our model using data from 1987 to 2009. Our results suggest two sources of rent dissipation under the existing sharing agreement: inefficient quota allocation and production inefficiencies due to inflexible national regulations. We discuss several alternatives to improve management.     

ConFlo III - an interface for high precision delta(13)C and delta(15)N analysis with an extended dynamic range

A newly developed interface coupling a CHN combustion device (elemental analyser 'EA') to an isotope ratio mass spectrometer is described and evaluated. The purpose of the device is to extend the dynamic range of delta(13)C and delta(15)N analysis from less than 2 orders of magnitude to more than 3 orders of magnitude. Carbon isotope ratio measurements of atropine as a model compound have been performed analysing between 1 μg to 5 mg C with acceptable to excellent precision (0.6 to 0.06 per thousand, delta-notation). The correction due to the blank signal is critical for sample amounts smaller than 4 μg C. The maximum sample weight is determined by the combustion capacity of the EA. Larger sample amounts are measured using dilution of a small part of the EA effluent with helium. The dilution mechanism works virtually free of isotope fractionation. Copyright 1999 John Wiley & Sons, Ltd.     

MIP sensors – the electrochemical approach

This review highlights the importance of coupling molecular imprinting technology with methodology based on electrochemical techniques for the development of advanced sensing devices. In recent years, growing interest in molecularly imprinted polymers (MIPs) in the preparation of recognition elements has led researchers to design novel formats for improvement of MIP sensors. Among possible approaches proposed in the literature on this topic, we will focus on the electrosynthesis of MIPs and on less common hybrid technology (e.g. based on electrochemistry and classical MIPs, or nanotechnology). Starting from the early work reported in this field, an overview of the most innovative and successful examples will be reviewed.     

Ion beam sputtering deposition of silver nanoparticles and TiOx/ZnO nanocomposites for use in surface enhanced vibrational spectroscopy (SERS and SEIRAS)

Hybrids consisting of silver nanoparticles (in varying fractions) and of TiOx/ZnO were prepared via top-down ion beam sputtering (IBS) deposition on silicon substrates. The deposited nanomaterials were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. It is shown that such composites represent a viable substrate for use in both surface enhanced Raman spectroscopy (SERS) and surface enhanced infrared absorption spectroscopy (SEIRAS), as exemplarily shown for crystal violet as the model analyte. The C-H bending mode at about 1181 cm^?1 and the C-N vibration at 1361 cm^?1 observed in the SERS and SEIRAS spectra, respectively, have been used as analytical signal. The substrate consisting of TiOx NPs with 33% fraction of silver provides the strongest enhancement in SERS (up to 10,000-fold), while TiOx/AgNPs with thickness of 2 and 1 nm in ion beam sputtering, respectively, provides the best sensitivity in SEIRAS. The substrates also display photocatalytic activity as shown by the degradation of adsorbed crystal violet under ultraviolet irradiation.

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Graphical abstract Schematic of the preparation of hybrid substrates consisting of Ag and TiOx/ZnO nanoparticles via ion beam sputtering deposition. They were applied in both surface enhanced Raman and surface enhanced infrared absorption spectroscopies using crystal violet as model analyte, showing enhancements up to >10,000-fold in Raman.