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1.
This paper studies the influence of poultice type and application techniques on the desalination efficiency of two limestone substrates having similar porosities (22–25%) but different pore size distributions: microporous Bateig Novelda and macro porous Tosca Rocafort stones. Three poultice types are compared: pure sepiolite (fine porous), sepiolite and aggregate (medium porous), and pure cellulose powder (coarse porous). Four application techniques are studied: (i) direct application on the stone, (ii) pre-wetting before poultice application, (iii) Japanese paper before application, and (iv) pre-wetting?+?Japanese paper before application. Samples were taken from poultices on the one hand, and from substrates at different depths on the other hand. Their content in soluble salts was estimated by ionic conductivity measurements. After three application runs, the best result for both substrates is achieved with the combined application of coarse- and fine-porous poultices (FPs) (desalination depth: 4.5/6?cm for macro/micro-porous substrates). The FP is also able to extract salts properly, but the desalination depth achieved is less important (3?cm). A direct poultice application without pre-wetting nor Japanese paper is to be preferred for both stone types. 相似文献
2.
ABSTRACTBoundary walls are neglected but important parts of historic urban environments, and they are often prone to serious deterioration. Understanding moisture and salt dynamics within boundary walls can help infer the causes and dynamics of deterioration. This investigation investigates the patterns of moisture, salt, and deterioration on a 300 year old limestone boundary wall in Worcester College, Oxford. Multiple methods to assess moisture and salts within and across the wall (electrical resistivity tomography, handheld resistivity-based moisture meter, paper pulp poultices, scanning electron microscopy, inductively coupled plasma optical emission spectrometry, and ion chromatography of small scale sampling of deteriorated limestone) were used in conjunction with decay mapping of both sides of the wall. The salt weathering strongly correlates with severely weathered zones at the wall and salts, mainly sulfates, seem to be the main agent of decay processes. The combined results demonstrate that the environmental influences driving stone decay can differ on a very small scale even at a comparatively simple structure like a boundary wall, and that repairs can have adverse effects if the patterns of salt and moisture dynamics are not sufficiently known. 相似文献
3.
First aid for flood-damaged paper using saltwater: The inhibiting effect of saltwater on mold growth
《文物保护研究》2013,58(3):164-171
AbstractWith the aim of developing a new easy-to-use method for rescuing flood-damaged paper, the effect of saltwater on the inhibition of fungal growth on paper was investigated. This procedure could be used instead of, or assisted by freeze drying. Cellulose-digesting Trichoderma reesei, three types of fungi representative of fungi growing on paper (T. reesei, Aspergillus terreus, and Aureobasidium pullulans) and various naturally airborne fungi were cultured on cellulosic materials in liquid media containing artificial seawater with different salt concentrations. The addition of salts successfully inhibited the growth of T. reesei on microcrystalline cellulose at the concentration of 3.2% (m/m) or higher. The critical salt concentration, 3.2%, is within the general range of salt content in seawater. Other solutions of salts similar to sodium chloride also inhibited fungal growth. Although the observed growth-inhibiting effect was attributed to the high osmotic pressure of the salt solution, physiological effects depending on ion species used were also considered to be possible. The growth of all three types of fungi on copy paper was inhibited effectively when the salt concentration was increased. The growth of various fungi on pure cellulose, with enough oxygen supplied to pores, was completely inhibited (as assessed by visual examination) for 24 days at salt concentrations of 3.5% (m/m) or greater. The fact that the effect of saltwater on cellulosic materials was observed even under optimum medium conditions implies that fungi would be considerably inhibited on flood-damaged paper immersed in saltwater. This method is a promising first aid measure when circumstances do not allow for flood-damaged paper to be dried immediately. 相似文献
4.
ABSTRACTConservation of wooden objects exposed outdoors is extremely difficult and complex due to their constant exposure to fluctuating weather conditions and biological degradation. Filling the gaps in such objects requires the use of specific materials that in particular can adapt to changes in wood dimensions in response to humidity variations. Various materials have been used so far for filling voids in wooden artefacts but none of them was entirely suitable. Therefore, the authors have attempted to provide the basic characteristics of the selected commonly used filling materials based on pine wood powder or glass microballoons as fillers and Paraloid® B-72, Klucel® G, or glutin glue as binders, as the first step in research aiming at developing new and more appropriate gap-fillers. Special attention was paid to the dimensional stability of filling materials upon drying and exposure to water vapour and liquid water. The overall results indicate that among the examined fills those consisting of Paraloid® B-72 and glass microballoons revealed best properties as they were relatively dimensionally stable upon drying and exposure to moisture – despite high absorption of water – and were quite easy to finish. Generally, better properties were observed for filling materials containing higher concentrations of adhesives and these materials will be modified in the next step of the research. Since the main drawbacks of the examined gap-fillers were low water resistance, poor dimensional stability upon drying or exposure to water vapour or liquid water, and fragility or friability, future research into their modification will head towards improvement of the above-mentioned properties. 相似文献
5.
Aisling Macken 《文物保护研究》2013,58(6):352-362
ABSTRACTThe impact of solvent vapour from two solvents, acetone and industrial denatured alcohol (IDA), commonly used in adhesive reactivation in textile conservation, when applied to artificially soiled silk fabric through either Gore-Tex® or Reemay® membranes for exposure times of either 1 or 3 min, was measured using microscopy and ImageJ to monitor the movement of the solid particulates of the soiling, and Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) to monitor the movement of the oily components. Analysis using these techniques successfully showed the movement of large particulates through the textile and a decrease in the presence of oil. Analysis with FTIR-ATR showed that the application of solvent vapour by a poultice method produces more than just a surface change and the vapour can penetrate far enough into the fibres to cause a change in the level of oil through the entire textile. The results showed that the solvents and barrier membranes have characteristic differences which impact on the changes on the soiling. The application of acetone produced a greater change in the movement of oil on the front and back of the samples than the application of IDA, while a comparison between the barrier membranes showed a greater change occurring in the level of oil with the use of Gore-Tex® rather than Reemay®. The time of exposure to solvent vapour made little difference to the changes to the textile soiling. Quantitatively significant results were gathered from analysis of the changes in the oil measured with FTIR-ATR, and qualitative changes in the large particulate soiling, demonstrating the potential usefulness of ImageJ open access software in future historic textile soiling monitoring studies. 相似文献
6.
Cellulose nitrate was widely used as a film base for photography, cinematography, and radiography in the first half of the twentieth century. Its stability is inherently poor and subject to environmental storage conditions. The risk of fire and the cross-infection effect on the cellulose acetate film stored at the same location necessitate that cellulose nitrate is identified within collections and stored separately. Not only medical archives, but also museums using radiography in their research may hold a sizeable amount of historical X-ray films. The Natural History Museum, London has been using film for X-radiography since before World War II. This suggests that some of the X-ray materials in its collections have a cellulose nitrate rather than ‘safety’ (cellulose acetate or polyester) film base. X-ray sheets rarely contain information related to their composition so science-based identification methods must be used. We propose the determination of nitrogen content in the film by organic elemental analysis (OEA) as a reliable method for the identification of films (X-ray, photographic, or cinematographic) with a cellulose nitrate base. Though it is a destructive method, the sample size required is small (<1?mg). This method does not require any sample preparation apart from weighing the samples and wrapping them in tin foil. OEA proved to be more accurate than the ‘float’ test in trichloroethylene and quicker and more straightforward to perform than infrared spectroscopy. 相似文献
7.
《文物保护研究》2013,58(4):178-186
AbstractA radioactive tracer has been used to monitor the deposition of lime, that occurs when friable limestone is treated with a lime poultice and multiple applications of limewater. It has been shown that more than half the lime deposited is in the outer 2mm of the stone. Further into the stone, the amount deposited is so small that no consolidating effect can reasonably be expected. 相似文献
8.
9.
《文物保护研究》2013,58(4):265-273
AbstractThis paper reports on the results of experiments to test for visual changes to paint systems after biocidal treatments, using a statistical binary procedure. Four biocides were selected, two of which are fungicides—a quaternary ammoniumorganotin mixture (BioMet 66®)in distilled water and an orthophenylphenol (Lysol®) in a spray— and two of which are fumigants—sulfuryl fluoride (SO2F6), a gas (Vikane®), and nitrogen gas (N2) (as an anoxant). The procedure used to assess the effect of the biocidal treatments was a random field visual scoring regimen by two paintings conservators. The tests were conducted on 30 combinations of linen, rabbitskin glue size, lead white oil ground and oil-based paints. The visual assessment procedure provided information on color change, gloss change, blanching, topography change and precipitation. The results indicated that Vikane adversely affected 10 of 11 pigment systems; Lysol adversely affected six of 11 pigment systems; BioMet 66 had a minor effect on four of 11 pigment systems; and nitrogen had no visible effect on any sample. The visual technique provided a quick and broad method for assessment of non-subtile visual changes. 相似文献
10.
ABSTRACT Currently, there is a lack of research on the migration and distribution of soluble salt solutions in the pores of fragile silicate cultural relics, especially the thermodynamic changes during crystallization, and the forces causing the destruction of cultural relics. Thus, this paper used infrared thermal imaging analysis and extended depth-of-field microscopy to observe the changes in temperature, morphology, migration, and crystallization rate of Na2SO4 solution – the most typical solution that causes damages to cultural relics – in the crystallization process and in different capillary pores. The results show that the formation of soluble salt crystal nuclei and subsequent crystal growth mainly occurred in the liquid phase region below the ambient temperature, and then the salt crystals in the deliquescent state became more compact due to the attractive force generated from liquid-phase water evaporation. Additionally, three stages of migration and crystallization of the salt solution in different capillary pores were found. Large-area crystals appeared in the capillary pore with a large diameter, and bubbles were generated. This is likely because the surface tension of the Na2SO4 solution decreased with increasing concentration, and the solubility of the air dissolved at the solid–liquid interface of the mouth of the capillary pore and the pressure in the capillary pore decreased. A self-designed double-layer contact surface internal pressure method and extended depth-of-field microscopy were used to carry out real-time online observation of the force applied on the contact surface during the crystallization of the salt solution. It was found that the airflow determined the direction of capillary movement of the solution, and water migration determined the laminar flow in the capillary pore. Salt crystallization played a role in distortion and shape-fixation of pores. Small spikes in the mass indicated that the expansion–contraction force generated by the salt solution during the crystallization process was in a state of constant change, and the degree of expansion was always slightly more significant than the change caused by contraction. Expansion forces dominated the surface of the sample. In this paper, the change in crystallization and the forces of the soluble salt solution were analyzed. 相似文献
11.
Leszek Krzemień Michał Łukomski Łukasz Bratasz Roman Kozłowski Marion F. Mecklenburg 《文物保护研究》2016,61(6):324-330
The drying shrinkage accumulation from exposure of freshly prepared gesso layers to relative humidity (RH) cycles was determined to elucidate the mechanism of craquelure pattern formation on panel paintings. The progresive drying shrinkage of the gesso is observed only under the cycles going to high RH levels which bring about transitions from brittle to ductile state of the material. The first incidence of fracture on the gesso layers occurred after a limited number of cycles ranging between a few and 100 for a range of layer thickness between 0.5 and 1?mm. The craquelure patterns stabilised also after a limited number of cycles (30 for the 1-mm thick layer). Upon increase in the gesso layer thickness, the strength of the layer is reduced and the spacing of shrinkage fractures increases. The study demonstrated that craquelure patterns, mimicking historical ones, can be realistically produced in laboratory conditions. Such studies would provide useful information for preparing specimens simulating historic panel paintings and would inform the current efforts on automatic, computer-aided classifications of crack formations on paintings. 相似文献
12.
ABSTRACTAspects of preventive conservation are central to the long-term preservation of archaeological sites such as Pompeii. Mitigating moisture ingress and its manifold effects on decay mechanisms such as salt degradation are of critical importance when planning durable conservation strategies. A suite of non-destructive techniques was used to diagnose decay mechanisms at an ancient tomb monument at the Porta Nocera Necropolis. Rising damp and salt contamination are shown to be actively contributing to on-going deterioration of the plaster surfaces. An existing shelter is shown to be inadequate in its protection. These initial results are used to inform a more in-depth, long-term survey as well as the design of a holistic preventive strategy. 相似文献
13.
《文物保护研究》2013,58(4):217-226
AbstractMany natural and synthetic products have been used for the consolidation of paint layers, but none have been thoroughly tested for this application. This is apparent for most of the synthetic and semi-synthetic adhesives for conservation, many of which are pure polymer resins and dispersions adapted from other industries. They were not specifically formulated with the appropriate properties for conservation, nor do they take advantage of some of the more recent developments in adhesive technology. BEVA® 371 is unique among adhesives used for consolidation treatments, as it is a multi-component mixture and was designed specifically for the conservation field using the best technology available at the time. However, the main focus of the research was its application as a lining adhesive. Thus, optical properties and stability, specifically color stability, were not thoroughly evaluated even though some lining applications that were first recommended could have benefited from this type of investigation. This paper will discuss the development of BEVA® 371, the chemistry, and roles of each component, and address a practical concern about the tack behavior of its replacement formulation, BEVA® 371b. 相似文献
14.
Mobile devices facilitate the use of mobile services that are similar to services used via fixed Internet connections. The objective of this article is to assess displacement effects between fixed and mobile Internet services, and to research the role of technical capabilities of mobile handsets and demographics as moderators. This study is based on a sample of 628 respondents who have access to fixed and mobile Internet services. The respondents' usage of services was analyzed. An online questionnaire was used to collect data on the use of information, communication, entertainment, and transaction services. Mobile Internet reinforces, rather than replaces, Internet usage. When people possess an iPhone® or (mobile) laptop, this reinforcement effect is present for entertainment services. With respect to transaction services, the Blackberry® makes a stronger case. With the exception of gender, demographic characteristics do not have a moderating effect. Women display a stronger reinforcement effect than men in relation to transaction services. To the best of our knowledge, no study to date has investigated the displacement effects of fixed Internet services by the mobile handset. This empirical study contributes to the literature regarding the displacement effects of mobile Internet services. 相似文献
15.
《文物保护研究》2013,58(2):66-75
AbstractIn contrast to fully tanned leather, that used by the Canadian Indians and Eskimos has poor durability. When stored under less than ideal conditions it becomes stiff and brittle, and restoration of such artifacts presents problems. The methods used for sound leather, such as fat liquoring or staking, cannot be used once the skin has deteriorated. A method used successfully is described. It consists of soaking the artifact in water to gain pliability and then replacing the water with organic liquid in order to avoid shrinkage on drying. Flexibility is preserved by permeation with an emulsion containing a stabilized olein soap, neat’s-foot oil and ethyl alcohol. Gut-skin may be treated by a modification of this emulsion. Fur poses a lesser problem because the skin is thin and can easily be permeated with an aqueous emulsion of sulfited sperm oil. Several examples of restoration are given. 相似文献
16.
《文物保护研究》2013,58(3):179-190
AbstractTesting of chemical stabilization treatments and desiccated and anoxic storage microclimates for the protection of archaeological iron stored in unsuitable climatic conditions was carried out by the conservation department of the Japanese Institute of Anatolian Archaeology at the Kaman-Kalehöyük excavation in Turkey. The chemical stabilization treatments involved alkaline sulfite, barium hydroxide and sodium hydroxide. Environmental stabilization was explored using RP-A oxygen scavengers in Escal® bags as part of the Revolutionary Preservation System (RP System®) manufactured by Mitsubishi Gas Chemical Company, Inc. The efficiency of the chemical treatments was examined by comparison with mechanically cleaned iron objects. The efficiency of the storage systems was determined by comparing the chemically and non-chemically treated objects in the RP System® using RP-A scavengers and in polyethylene ziplock bags containing silica gel. The efficiency of these treatments and storage systems was examined and assessed at Kaman after a period ranging from 7 to 9 years. The anoxic and desiccating properties of the RP System® resulted in superior protective qualities over polyethylene bags with silica gel. The RP System® compensated for inadequate chemical stabilization and protected iron that had not been chemically stabilized. 相似文献
17.
Transaction logs from online search engines are valuable for two reasons: First, they provide insight into human information-seeking behavior. Second, log data can be used to train user models, which can then be applied to improve retrieval systems. This article presents a study of logs from PubMed®, the public gateway to the MEDLINE® database of bibliographic records from the medical and biomedical primary literature. Unlike most previous studies on general Web search, our work examines user activities with a highly-specialized search engine. We encode user actions as string sequences and model these sequences using n-gram language models. The models are evaluated in terms of perplexity and in a sequence prediction task. They help us better understand how PubMed users search for information and provide an enabler for improving users’ search experience. 相似文献
18.
Roel Hendrickx Ester S.B. Ferreira Jaap J. Boon Guylaine Desmarais Dominique Derome Lora Angelova 《文物保护研究》2017,62(7):393-409
Moisture is a driving factor in the long-term mechanical deterioration of canvas paintings, as well as for a number of physico–chemical degradation processes. Since the 1990s a number of publications have addressed the equilibrium hygroscopic uptake and the hygro-mechanical deformation of linen canvas, oil paint, animal glue, and ground paint. In order to visualise and quantify the dynamic behaviour of these materials combined in a painting mock-up or reconstruction, we have performed custom-designed experiments with neutron radiography and nuclear magnetic resonance (NMR) imaging. This paper reports how both techniques were used to obtain spatially and temporally resolved information on moisture content, during alternate exposure to high and low relative humidity, or in contact with liquids of varying water activities. We observed how the canvas, which is the dominant component in terms of volumetric moisture uptake, absorbs and dries rapidly, and, due to its low vapour resistance, allows for vapour transfer towards the ground layer. Moisture desorption was generally found to be faster than absorption. The presence of sizing glue leads to a local increase of moisture content. It was observed that lining a painting with an extra canvas results in a damping effect: i.e. absorption and drying are significantly slowed down. The results obtained by NMR are complementary to neutron radiography in that they allow accurate monitoring of water ingress in contact with a liquid reservoir. Quantitative results are in good agreement with adsorption isotherms. The findings can be used for risk analysis of paintings exposed to changing micro-climates or subjected to conservation treatments using water. Future studies addressing moisture-driven deformation of paintings can make use of the proposed experimental techniques. 相似文献
19.
This paper investigates the effectiveness of using MeSH® in PubMed through its automatic query expansion process: Automatic Term Mapping (ATM). We run Boolean searches based on a collection of 55 topics and about 160,000 MEDLINE® citations used in the 2006 and 2007 TREC Genomics Tracks. For each topic, we first automatically construct a query by selecting keywords from the question. Next, each query is expanded by ATM, which assigns different search tags to terms in the query. Three search tags: [MeSH Terms], [Text Words], and [All Fields] are chosen to be studied after expansion because they all make use of the MeSH field of indexed MEDLINE citations. Furthermore, we characterize the two different mechanisms by which the MeSH field is used. Retrieval results using MeSH after expansion are compared to those solely based on the words in MEDLINE title and abstracts. The aggregate retrieval performance is assessed using both F-measure and mean rank precision. Experimental results suggest that query expansion using MeSH in PubMed can generally improve retrieval performance, but the improvement may not affect end PubMed users in realistic situations. 相似文献
20.
ABSTRACTIn the Mogao Grottoes of Dunhuang, China, the ambient relative humidity (RH) fluctuation in the caves is the main cause for the deterioration that has been observed, especially the deterioration of the earthen plaster and wall paintings linked to the presence of NaCl and Na2SO4 salt contaminants. To help identify the mechanism responsible for this salt-related deterioration and provide a theoretical basis for the development of a preventive conservation regime, this study addressed the basic moisture adsorption mechanisms of earthen plaster with soluble salts by taking an experimental approach. It is shown that, as ambient RH increases, the moisture adsorption process of the plaster containing the soluble salts can be regarded to have three basic stages, as evidenced by the results of the moisture adsorption tests performed on earthen plaster samples with different NaCl or Na2SO4 contents at various humidity levels. The moisture adsorption mechanism and its determining factors at each stage are also analysed. In addition, it is suggested that the hygroscopicity of the plaster structure and the interaction between the different kinds of salts in the plaster, which makes the dissolution or hydration of the salt in the plaster pores much easier, should be considered more seriously regarding increases in the ambient RH in the caves. 相似文献