Estudio del comportamiento de pinturas acrílicas sobre tablero contrachapado tras envejecimiento artificial

Entre los soportes más empleados en arte contemporáneo se encuentran los tableros derivados de la madera. Hasta el momento, las investigaciones para determinar la influencia de un soporte de tablero contrachapado en capas pictóricas acrílicas así como las condiciones óptimas para su conservación, resultan insuficientes o completamente ausentes. En la elaboración de estos tableros se utilizan adhesivos para darles consistencia pero la influencia de estos adhesivos en las capas pictóricas artísticas estará en función del tipo de tablero, del tipo de adhesivo empleado, de las condiciones ambientales y de las características de las capas pictóricas. Es evidente pues, la necesidad de modelos comparativos. Por todos estos motivos, el objetivo principal de esta investigación ha sido comprender la transformación que experimentan estos materiales durante su envejecimiento y las causas que pueden desestabilizar las obras, con el fin de adoptar las medidas necesarias para evitar un envejecimiento prematuro. Mediantela Espectroscopía Infrarroja por Transformada de Fourier FTIR se han analizado los cambios sufridos por modelos experimentales realizados con pinturas acrílicas imprimidas sobre tablero contrachapado trasser sometidos a ciclos de envejecimiento por choquetérmico (Cold-check test) y envejecimiento en condiciones de alta humedad

Recent trends and developments in pyrolysis-gas chromatography: review

Pyrolysis-gas chromatography (Py-GC) has become well established as a simple, quick and reliable analytical technique for a range of applications including the analysis of polymeric materials. Recent developments in Py-GC technology and instrumentation include laser pyrolysis and non-discriminating pyrolysis. Progress has also been made in the detection of low level polymer additives with the use of novel Py-GC devices. Furthermore, it has been predicted that future advances in separation technology such as the use of comprehensive two-dimensional gas chromatography will further enhance the analytical scope of Py-GC

Evaluation of a gelatin-based adhesive for historic paintings that incorporates citronella oil as an eco-friendly biocide

[EN] The presented study focuses on evaluating the efficiency of a gelatin-based product that incorporates a plasticizer (glycerol) and a biocide (citronella oil), proposed as an eco-friendly adhesive for polychrome decoration applied in different parts of the architectural complex of the Longshan Temple in Lukang (eighteenth century, Taiwan). Seven laboratory physico-chemical tests were performed: (a) viscosity measurement; (b) drying curves; (c) moisture content determination; (d) water vapor permeability test; (e) mechanical test; (f) adhesion test; (g) susceptibility to fungi colonization test, which provide information on the workability, water content and water barrier properties, as well as mechanical, adhesion, and the biocide properties of the proposed product. The obtained results indicate that the workability, mechanical and adhesive properties of the new adhesive are adequate. Permeability in polychromies is slightly reduced due to the additional barrier effect of the adhesive incorporated into the paint film. The efficiency of citronella oil for preventing the growth of fungus Aspergillus niger on paintings consolidated with the adhesive was also probed. In parallel to these laboratory trials, the micro-invasive tests carried out, using nanoindentation combined with atomic force microscopy (NI-AFM), provided direct evidence for the improvement in the mechanical properties induced by applying the new adhesive to the original polychromies.This work was supported by the Spanish Ministerio de Economia, Industria y Competitividad (MINECO), the Fondo Europeo de Desarrollo Regional (ERDF), and the Agencia Estatal de Investigacion (AEI).Lee, Y.; Martín Rey, S.; Osete Cortina, L.; Martín-Sánchez, I.; Domenech Carbo, MT.; Bolivar-Galiano, F. (2018). Evaluation of a gelatin-based adhesive for historic paintings that incorporates citronella oil as an eco-friendly biocide. Journal of Adhesion Science and Technology. 32(21):2320-2349. https://doi.org/10.1080/01694243.2018.1477411S23202349322

Very high energy gamma-ray observation of the peculiar transient event Swift J1644+57 with the MAGIC telescopes and AGILE

Context. On March 28, 2011, the BAT instrument on board the Swift satellite detected a new transient event that in the very beginning was classified as a gamma ray burst (GRB). However, the unusual X-ray flaring activity observed from a few hours up to days after the onset of the event made a different nature seem to be more likely. The long-lasting activity in the X-ray band, followed by a delayed brightening of the source in infrared and radio activity, suggested that it is better interpreted as a tidal disruption event that triggered a dormant black hole in the nucleus of the host galaxy and generated an outflowing jet of relativistic matter. Aims. Detecting a very high energy emission component from such a peculiar object would be enable us to constrain the dynamic of the emission processes and the jet model by providing information on the Doppler factor of the relativistic ejecta. Methods. The MAGIC telescopes observed the peculiar source Swift J1644+57 during the flaring phase, searching for gamma-ray emission at very-high energy (VHE, E > 100 GeV), starting observations nearly 2.5 days after the trigger time. MAGIC collected a total of 28 h of data during 12 nights. The source was observed in wobble mode during dark time at a mean zenith angle of 35 degrees. Data were reduced using a new image-cleaning algorithm, the so-called sum-cleaning, which guarantees a better noise suppression and a lower energy threshold than the standard analysis procedure. Results. No clear evidence for emission above the energy threshold of 100 GeV was found. MAGIC observations permit one to constrain the emission from the source down to 100 GeV, which favors models that explain the observed lower energy variable emission. Data analysis of simultaneous observations from AGILE, Fermi and VERITAS also provide negative detection, which additionally constrain the self-Compton emission component