Feasibility of ultrafast picosecond laser cleaning of soiling on historical leather buckles

The aim of the research is to present a system recently developed and used for automated cleaning of artworks and to examine the suitability of using this ultrafast and precise computed-scanning picosecond laser (1064 nm) with a repetition rate of 10 kHz and a temporal pulse length of 10 ps for the removal of soiling from leather buckles without damaging the leather substrate. Preliminary tests will be performed with the model artificially aged vegetable tanned samples to determine the leather damage threshold fluence and the soiling ablation threshold fluence before using a laser for the removal of the soiling from a historical leather buckle. As laser cleaning requires a physical parameterization for optimization of cleaning accompanied with an assessment of the morphological and chemical changes of leather, an investigations were performed to determine the leather damage and ablation threshold fluences of artificially aged and historical vegetable tanned leather using a number of analytical techniques including differential scanning calorimetry, optical microscopy, scanning electronic microscope with energy dispersive X-ray analysis, colorimetry and Fourier transform infrared spectroscopy have been used. Following optimization trials of the picosecond laser cleaning parameters on model leather samples, satisfactory removal of the soiling over the historical leather surface is achieved

Indoor air pollutants and their seasonal monitoring in European museums

Abstract The monitoring of indoor air pollutants is an important part of the management of heritage collections. In this work, acetic acid, formic acid, formaldehyde, acetaldehyde and NO2 were measured with passive samplers along with temperature and relative humidity once per season in seven European institutions of different sizes with different types of objects. The measurements were carried out in a variety of locations, from modern and old display cases in exhibition rooms of different sizes to storage rooms and their enclosures for different types of objects. The results were evaluated based on the characteristics of the sampling locations and the extent to which the changing seasons affect pollutant concentrations were estimated. The dataset obtained from this study can be a valuable asset as a snapshot of the current state of the environment in European heritage collections

Development of dose-response functions for historic paper degradation using exposure to natural conditions and multivariate regression

Many collections of documents, manuscripts, and works of art on paper are prone to degradation due to a complex interplay of extrinsic and intrinsic factors. The aim of this study was to examine the simultaneous effect of multiple degradation agents on selected non-model types of paper in natural environments, and the relative effect of environmental parameters (heat, humidity, light and pollution) compared to material parameters (pH, fibre composition and presence of additives). An exposure experiment was set up to investigate visual and chemical changes of 12 different types of paper in real time in different environmental conditions over a 1.5-year period at 11 sites across Europe and North Africa, sheltered from UV light and precipitation. Suitable environmental monitoring equipment, such as data loggers and gas samplers, and analytical methods to characterise sample degradation, specifically spectrocolorimetry and capillary viscometry, were used to estimate alterations in visual appearance and degree of cellulose polymerisation, which are the most important properties of paper in the heritage context. Multiple linear regression and principal component regression were used to interpret the large volume of data and calculate a set of dose-response functions. The results of this study not only suggested that most of the considered variables are of significance in relation to changes in colour and in average molecular weight, but also revealed a number of meaningful interactions between these variables. Based on the assessment of the relative contributions of environmental and material-related variables to the natural ageing processes of paper, the dose-response functions proposed in this study enable prioritisation of degradation factors in environmental management of paper-based collections and in historic paper degradation studies; however, further work is required to increase accuracy and understanding of the chemistry of degradation

Risk analysis for preventive conservation of heritage collections in Mediterranean museums: case study of the museum of fine arts in Alexandria (Egypt)

Abstract The impacts of climate change on heritage collections in Mediterranean museums are serious and lead to accelerated material degradation, loss of value, increasing conservation costs and climatisation. Climate change scenarios and simulation models have been developed to predict the extreme and average future environmental conditions and to assess the future long-term risks caused by global warming for museum buildings and their collections in Mediterranean countries, with Egypt being particularly at risk. This paper presents the results of the risk analysis of the indoor and outdoor environments in Alexandria Museum of Fine Arts (AMFA) in Egypt to provide an overview of the current situation of conservation and museum management and to provide evidence-based data to support decision-making regarding preventive conservation given the museum's limited funding, capacity and resources. Unfortunately, the air quality in the museum cannot be considered satisfactory and specific measures need to be taken to improve the level of air quality and museum and building management. The results enabled an assessment of indoor air quality and provided information on potential risks to the museum building and collections, including variations in temperature (T) and relative humidity (RH), concentrations of NO2, SO2, O3, CO2, acetic and formic acid and lighting conditions, as well as the location and management of the museum. The results necessitate the development of a preventive conservation plan to address the challenges associated with high T/RH fluctuations and pollution pressure. This requires more regular use of the HVAC system within certain T/RH set points as well as minimising light exposure and the use of UV-filtering glazing. Care should be taken to ensure that housekeeping and emergency preparedness reduce the damping and salt florescence in the museum building. However, dealing with the impact of climate change on indoor and outdoor environments and museum collections in Mediterranean museums requires a holistic and adaptive approach that includes joint collaboration, research, training and strategic planning to ensure the long-term preservation of valuable cultural heritage collections in different climates with customised adaptations based on local environmental conditions, resources and needs. Resilience planning should be region-specific and take into account the potential impacts of extreme weather events, sea level rise and other climate-related challenges

Environmentally induced colour change during natural degradation of selected polymers

The aim of this study was to examine the simultaneous effect of multiple degradation agents on selected polymer materials in natural environments, and the relative effect of atmospheric pollutants compared to other environmental parameters (heat, humidity and light). A complex exposure experiment was set up to investigate the colour change of 17 different types of polymers (cellulose carboxylate, polyamide, poly(vinyl chloride), polystyrene, polyethylene, polypropylene, polycarbonate, polyurethane, and melamine formaldehyde and phenol formaldehyde resins) in real time in different environmental conditions over a 2-year period at 11 sites across Europe and North Africa, sheltered from UV light and precipitation. Suitable environmental monitoring equipment, such as data loggers and gas samplers, and analytical methods to characterize sample degradation, specifically non-destructive spectrocolorimetry, were used, as colour is one of the most important properties of polymers in art and heritage contexts. A methodology based on multivariate data analysis was used for data interpretation. The results of this study suggested that light and concentration of NO2 are the most important environmental variables leading to colour change in polymer materials, and to a lesser extent the concentration of O3, while other factors such as heat, relative humidity and the concentration of SO2 were less significant. Based on the assessment of the relative contributions of light and traffic-generated pollutants to the natural ageing processes of synthetic polymers, this study enables prioritisation of environmental degradation factors in environmental management of collections and in historic material degradation studies.The authors are grateful to Marina Bicchieri, Linda Cséfalvayová, Rena Fenech, Casimir Iwaszkiewicz, Marko Kmetič, Irena Oven, Matevz Strlič and Mikel Zubiaga for technical assistance. The authors gratefully acknowledge funding from the European Commission 7th Framework Programme under the grant agreement no. 212218 (Popart–Preservation of plastic artefacts in museum collections).Peer reviewe

Evaluation of Tribulus terrestris Extracts Relative to Metformin on Oxidative Stress and Histopathology of the Liver for Diabetic Male Rats

Insulin-dependent diabetes mellitus (IDDM) is a metabolic condition that induces blood glucose levels to rise due to insulin deficiency and the formation of reactive oxygen species (ROS). The purpose of this study is to assess how efficient the antioxidant extracts Tribulus terrestris (TT) and metformin (MET) are in reducing oxidative stress and histopathology produced by streptozotocin in rat hepatocytes. The 36 male rats weighing 170–190 g of this study were randomly sorted into 6 groups. The first group was considered a normal control group, and the second and third groups were normal and remedy with MET and TT extract, respectively. The fourth group was positive diabetic, and the fifth and sixth groups were diabetic rats that were treated with MET and TT extract, respectively. Lipid peroxidation (LPO), catalase (CAT), glutathione-S-transferase (GST), and glutathione (GSH) were detected, and the histopathology of the liver was evaluated after 8 weeks of treatment. Compared to regulation, morphological changes in the liver were found in diabetic animals, with a rise in LPO and a change in GSH levels as well as CAT and GST activities. The oxidative stress and histological architecture of the hepatocytes caused by hyperglycemia were improved as a result of therapy in the rats with MET and TT extract. Because of its antioxidant activities, diabetic rats with TT extract are more effective than MET in normoglycemia and hepatocyte reconditioning. Beneficial intervention tends to benefit primarily from direct ROS scavenging and CAT, GST, and GSH regeneration

Evaluation and modelling of the environmental performance of archival boxes

Archival boxes are used as a preventive measure to control the microenvironment in museums and archives storages. However, their efficiency in protecting valuable artefacts from fluctuations in relative humidity (RH) is not yet fully understood. In this study, the environmental performance of different archival boxes with different configurations (size, design, presence of holes/paper material, cardboard types, surface modification) was included in the evaluation of internal environment (RH). The effectiveness of archival boxes on reducing relative humidity fluctuations was investigated by testing various properties of boxes and boards, such as air exchange rates (AER), moisture sorption and water vapour transmission rates (WVTR). While most cardboard boxes showed only a limited buffering against the humidity ingress, strategies such as surface modification limited the interaction of a box with the external environment, resulting in a more stable internal environment. Material and box properties, such as moisture sorption, AER and WVTR proved to be useful quantitative tools for assessing the environmental performance of the selected archival boxes