Evaluación de los efectos causados por el uso de poli (vinil acetato) —PVAc— en los entelados de carteles modernos

En este trabajo de investigación se estudian los efectos causados por el uso de poli (vinil acetato) —PVAc— en el entelado de carteles modernos para evaluar el estado actual de las obras intervenidas con este tratamiento, los efectos de la presencia del adhesivo en su estado de conservación, y las alteraciones que pueden aparecer en el futuro comprometiendo la estabilidad a largo plazo.

La pintura mural romànica: estudi de la tècnica i anàlisi dels materials

Els objectius de partida d’aquesta recerca han estat l’estudi de les tècniques i dels materials dela pintura mural medieval a Catalunya, tot i establint paraŀlelismes amb el coneixement que ensaporten els tractats tècnics d’època medieval. S’ha revisat també l’estat actual del coneixement sobre les tècniques d’alguns conjunts de pintura mural aragonesos i d’àmbit europeu.

Terracota, Arquitectura y Barcelona: siglos XIX y XX

Creemos que la terracota, en cuanto que materia, posee sufi cientes cualidades, por sí mismay por su vinculación con la arquitectura en la que se ubica, que la hacen merecedora de unestudio profundo y de un acercamiento respetuoso. Un producto cerámico que aporta comopropiedad fundamental su carácter escultórico. Valores que pretendemos sean totalmente explícitos, con la condición que sean fácilmente reconocibles. Un material que defi ne un momento de la historia y de la historia de la arquitectura de Barcelona, incompleta sin el estudio sistemático que presentamos.

Assessing the pH and DP of canvasses with NIR spectroscopy

The canvas support in easel paintings is composed mainly of cellulose. One of the maindegradation paths of cellulose is acid-catalysed hydrolysis, which means that in an acidic environment (low pH), its degradation proceeds at a faster rate (Strlič et al., 2005).The main effect of acid-catalysed hydrolysis is the breaking up of the polymer chains,measured by the “Degree of Polymerisation” (DP). The lowering of the DP value impliesa lower mechanical strength of the textile (Scicolone, 1993), and thus this parameter canbe used to monitor degradation. Knowing these two parameters can, therefore, be veryinformative regarding the condition of the canvas support.

El deterioro del soporte de contrachapado: propuesta de restauración de 9 obras de Francesc Artigau

Francesc Artigau (Barcelona 1940) pintó en los años setenta una serie de obras al temple sobre contrachapado. De éstas, dos trípticos y un díptico estaban destinados a decorar un hotel en Masquefa (Lérida), pero fueron rechazados por su atrevimiento y sus colores, y quedaron en propiedad del agente intermediario, junto con otra obra de menor formato. Las nueve obras sufrieron después un grave proceso de deterioro causado por una conservación en condiciones deplorables, al estar almacenadas en un local en el que se guardaba un grupo indeterminado de perros. Las obras, actualmente propiedad del Museo de l'Hospitalet (Barcelona), han permanecido fuera del circuito artístico hasta la actualidad. Se exponen los primeros resultados de la fase de estudio del soporte de las nueve obras y las propuestas de intervención en los soportes dañados

Los adhesivos empleados en el entelado de carteles modernos. Uso de la Espectrometría de Masas de Ionización/Desorción por Láser asistida por Matriz y analizador de Tiempo de Vuelo (MALDI-TOF-MS) para la identificación de éteres de celulosa

"XVIII Congreso Internacional de Conservación y Restauración de Bienes Culturales - 18th International Meeting on Heritage Conservation", Granada 9 al 11 novembre de 2011

A study of the effects of PVAC on works of art on paper and wood: pH and colour change

This paper presents the preliminary findings of pH and colour measurements carried out on artworks on paperand on wood that had been treated with a poly(vinyl acetate) (PVAC) based adhesive in the 1980s. In both cases, areas treated with PVAC proved to be less acidic than untreated areas. Contrary to expectations, the conservation treatments have not, as yet, increased acidity levels in the objects under study. Colour measurements of the works on paper showed that those that had been backed with a cotton fabric using a mixture of methylcellulose and PVAC were less yellow than those from the same print run that had not been backed. This finding suggests that the backing somehow prevented the natural degradation of the support. In view of these preliminary results, further research is clearly needed. This study forms part of a broader ongoing project to assess the role of PVAC in the conservation of a range of cultural assets.

Recerques sobre el comerç baix-imperial del nordest de la Península Ibèrica

Aquestes recerques recolzen basicament en les poques dades escrites - indosa l'epigrafia - que encaixen dins la sincronia de la darrera antiguitat i que fan referencia al nord-est de la Península o bé permeten endinsar-nos una mica més en el :coneixement de l'activitat comercial d'aquest momento . A la informació que hem collit deIs textos hi afegim, bé que d'una manera molt succinta, les dades tangibles fornides per la numismatica i l'arqueologia intentant així, quan és possible, traspuar un xic més els barratges que s'aixequen davant l'arada que mena i empeny l'investigador. La punyent escassetat quantitativa i qualitativa de les fonts d'aquesta epoca encara s'aguditza més a l'hora de rastrejar la informació que ens puguin proporcionar devers l'activitat comercial i, d'altra banda, no cal dir que aquesta parquedat lcondiciona, i adhuc ens atreviríem a dir que determina, els resultats que es poden obtenir d'aquest període, ja que sovint hom no pot recórrer altres viaranys. Així, per exemple, els textos literaris, de conservació rara i atzarosa, solament ens donen petites dades sobre el comer9 llunya que solcava la Mediterrania i es marceixen a l'hora de valorar els intercanvis locals i més o menys restringits, els quals a moltes zones i moltes vegades tenen, versemblantment, una importancia molt més rellevant que el mercadeig de llarg recorregut cenyit a un nombre relativament limitat de productes.

Using spatially distributed parameters and multi-response objective functions to solve parameterization of complex applications of semi-distributed hydrological models

Application of semi-distributed hydrological models to large, heterogeneous watersheds deals with several problems. On one hand, the spatial and temporal variability in catchment features should be adequately represented in the model parameterization, while maintaining the model complexity in an acceptable level to take advantage of state-of-the-art calibration techniques. On the other hand, model complexity enhances uncertainty in adjusted model parameter values, therefore increasing uncertainty in the water routing across the watershed. This is critical for water quality applications, where not only streamflow, but also a reliable estimation of the surface versus subsurface contributions to the runoff is needed. In this study, we show how a regularized inversion procedure combined with a multiobjective function calibration strategy successfully solves the parameterization of a complex application of a water quality-oriented hydrological model. The final value of several optimized parameters showed significant and consistentdifferences across geological and landscape features. Although the number of optimized parameters was significantly increased by the spatial and temporal discretization of adjustable parameters, the uncertainty in water routing results remained at reasonable values. In addition, a stepwise numerical analysis showed that the effects on calibration performance due to inclusion of different data types in the objective function could be inextricably linked. Thus caution should be taken when adding or removing data from an aggregated objective function.

The structure of Mediterranean rocky reef ecosystems across environmental and human gradients, and conservation implications

Historical exploitation of the Mediterranean Sea and the absence of rigorous baselines makes it difficult to evaluate the current health of the marine ecosystems and the efficacy of conservation actions at the ecosystem level. Here we establish the first current baseline and gradient of ecosystem structure of nearshore rocky reefs at the Mediterranean scale. We conducted underwater surveys in 14 marine protected areas and 18 open access sites across the Mediterranean, and across a 31-fold range of fish biomass (from 3.8 to 118 g m22). Our data showed remarkable variation in the structure of rocky reef ecosystems. Multivariate analysis showed three alternative community states: (1) large fish biomass and reefs dominated by non-canopy algae, (2) lower fish biomass but abundant native algal canopies and suspension feeders, and (3) low fish biomass and extensive barrens, with areas covered by turf algae. Our results suggest that the healthiest shallow rocky reef ecosystems in the Mediterranean have both large fish and algal biomass. Protection level and primary production were the only variables significantly correlated to community biomass structure. Fish biomass was significantly larger in well-enforced no-take marine reserves, but there were no significant differences between multi-use marine protected areas (which allow some fishing) and open access areas at the regional scale. The gradients reported here represent a trajectory of degradation that can be used to assess the health of any similar habitat in the Mediterranean, and to evaluate the efficacy of marine protected areas.

The Upper Oligocene of Montgat (Catalan Coastal Ranges, Spain): new age constraints to the western Mediterranean Basin opening

The Oligocene deposits of Montgat are integrated in a small outcrop made up of Cenozoic and Mesozoic rocks located in the Garraf-Montnegre horst, close to the major Barcelona fault. The Oligocene of Montgat consists of detrital sediments of continental origin mainly deposited in alluvial fan environments; these deposits are folded and affected by thrusts and strike-slip faults. They can be divided in two lithostratigraphic units separated by a minor southwest-directed thrust: (i) the Turó de Montgat Unit composed of litharenites and lithorudites with high contents of quartz, feldspar, plutonic and limestone rock fragments; and (ii) the Pla de la Concòrdia Unit composed of calcilitharenites and calcilithorudites with high contents of dolosparite and dolomicrite rock fragments. The petrological composition of both units indicates that sediments were derived from the erosion of Triassic (Buntsandstein, Muschelkalk and Keuper facies), Jurassic and Lower Cretaceous rocks (Barremian to Aptian in age). Stratigraphic and petrological data suggest that these units correspond to two coalescent alluvial fans with a source area located northwestwards in the adjoining Collserola and Montnegre inner areas. Micromammal fossils (Archaeomys sp.) found in a mudstone layer of the Pla de la Concòrdia Unit assign a Chattian age (Late Oligocene) to the studied materials. Thus, the Montgat deposits are the youngest dated deposits affected by the contractional deformation that led to the development of the Catalan Intraplate Chain. Taking into account that the oldest syn-rift deposits in the Catalan Coastal Ranges are Aquitanian in age, this allows to precise that the change from a compressive to an extensional regime in this area took place during latest Oligocene-earliest Aquitanian times. This age indicates that the onset of crustal extension related to the opening of the western Mediterranean Basin started in southern France during latest Eocene-early Oligocene and propagated southwestward, affecting the Catalan Coastal Ranges and the northeastern part of the Valencia trough during the latest Chattian-earliest Aquitanian times.

Les Tres Gorges de la Xina: enorme embassament... enormes conseqüències

Una de les obres públiques més grans mai escomeses per l'home, i a la Xina possiblement només comparable a la Gran Muralla, és a punt d¿esdevenir una realitat: l'embassament de les Tres Gorges. Una enorme paret de formigó al més llarg i cabalós dels rius xinesos, el Iang-Tsé, acabarà amb una tràgica història de terribles inundacions i milers de morts, alhora que produirà una ingent quantitat d'electricitat (la central hidroelèctrica annexa a la presa serà la més gran de tot el món) i convertirà el riu en la principal via de comunicació fluvial del planeta. La construcció de embassament, però, suposarà també enormes i greus conseqüències.

2010, Any Internacional de la Biodiversitat

El Conveni per a la Diversitat Biològica (CBD) de les Nacions Unides ha declarat l'any 2010 com a Any Internacional de la Biodiversitat. Durant tot l'any se succeiran activitats de tota mena per difondre la problemàtica de la necessitat de preservar la diversitat biològica i estimular l'adopció de mesures per a aconseguir¿ne la conservació efectiva.

Semàfor vermell

El projecte de pressupost general de l'Estat inclou una retallada del 28% en el capítol 6 (inversions directes) referent als centres i instituts de recerca de Catalunya. Aquesta és una més de les notícies que darrerament estan posant contra les cordes el futur de la recerca al nostre país.