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The paper presents the experimental study of the effect of ions of different mobilities (H + , Cl − , Li + and OH − ) in electrosprayed water solutions under atmospheric pressure conditions in air and in SF 6 background gas. Generally, at the atmospheric air conditions, the main difference between water electrospray (ES) in positive and in negative polarities is the shape and elongation direction of the water jets propagating from the charged nozzle. These phenomena can be associated with the movement of ions in water (i.e. the mobility of ions) or with the influence of the corona discharge and its ionic space charge. A comparison of HCl and LiOH water solutions with inversed mobility ratios of cations and anions showed that the mobility of ions inside the liquid is not an important parameter determining this difference between two ES polarities. The combined measurements in atmospheric air and SF 6 gas clearly showed that the only important factor determining the different shapes and propagations of the water jets for both polarities is the corona discharge and its ionic space charge. [ABSTRACT FROM AUTHOR]

Abstract: Water solutions of organic dye Direct Red 79 were treated by DC high voltage created by diaphragm discharge (input power up to 160W). Higher dye decoloration (60% after 40min) was observed in the anode part of the reactor by UV–VIS spectroscopy. Recorded absorption spectra showed shifts of absorption maximum to lower wavelength values that were related to the formation of stable degradation products. Absorption spectra obtained in the cathode part of the diaphragm reactor produced only negligible shifts of absorption maximum and the dye decomposition rate reached 25% after 80min of the treatment. HPLC-MS method revealed five main compounds in the anode part and another three ones in the cathode part. Analysis of identified products showed on the initial decomposition of one azo-group in the original dye molecule. Significant changes of solution properties during the diaphragm discharge were observed, too. Solution conductivity increased in both parts of the reactor. Solution pH dropped from the initial neutral value to acidic conditions (up to 3) in the anode part and to alkaline conditions (up to 10) in the cathode part. Changes were induced by formation of reactive species by the discharge and by electrochemical reactions on electrodes. [Copyright &y& Elsevier]

• The Laksil/parylene C conservation coating for iron artefacts is developed. • Much better protection compared to conventional conservation coating is achieved. • The appearance of artefacts is not changed in terms of colour. • The coating is entirely removable and thus the conservation process is reversible. Combinations of different acrylic resins and microcrystalline waxes are most often used for conservation and preservation these days. However, their properties are not sufficient and satisfactory in many ways. A novel barrier coating for the conservation of iron archaeological artefacts composed of parylene C polymer and Laksil lacquer is proposed within this article. Parylene C is a commercial name of poly(chloro- p -xylylene) polymer, and it was prepared via modified chemical vapour deposition. Parylene removability was ensured through the xylene soluble interlayer made of Laksil silicone-acrylic lacquer which was applied between a protected iron model substrate and parylene thin film. The corrosion tests in salt spray showed excellent barrier properties of Laksil/parylene bilayer. The surface roughness measured by the profilometry and the surface morphology shown by the SEM displayed the synergic effect between the Laksil and parylene layer which leads to the exceptional barrier and anticorrosion function of Laksil/parylene bilayer. First, the Laksil layer flattened out rough surface of a substrate; second, thereon deposited parylene film became smooth and defect free and acted as a good diffusion barrier. The colouristic measurements proved that the bilayer does not change the appearance of item, in terms of colour. The EDX and TGA confirmed entirely successful removal of bilayer and thus the reversibility of conservation treatment is enabled. The characteristics of Laksil/parylene bilayer were compared with the conventional conservation coating composed of Paraloid B72 acrylic resin and Revax microcrystalline wax prepared by professional conservators. The Laksil/parylene bilayer demonstrated significantly superior properties in this comparison. [ABSTRACT FROM AUTHOR]