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• BC/ZnO nanocomposite strengthens paper and improves aging resistance. • The nanocomposite imparts antifungal properties to paper. • The nanocomposite helps in deacidification of paper. Paper, commonly used as an information carrier, can become acidified and brittle over time. In this study, 0.3 % bacterial cellulose (BC) composite with 1.0% zinc oxide (ZnO) nanoparticles was prepared and used to coat brittle book paper for deacidification and consolidation. The BC/ZnO nanocomposite was characterized using zeta potential, micro morphology, elemental mapping, X-ray photoelectron spectra, Fourier transform infrared, and thermogravimetric analyses. The results indicated that the composite exhibited good stability. ZnO nanoparticles were bonded to the hydroxyl groups on BC, enhancing the thermal stability of BC. The composite was uniformly sprayed on the paper surface, and the mechanical properties, color difference, readability, pH, and micromorphology of the paper samples were examined before and after the treatment. The BC/ZnO nanocomposite exhibited good deacidification and consolidation effects on paper samples with low impact on the original paper appearance. Moreover, the BC/ZnO nanocomposite showed a good inhibitory effect on fungi growth on paper. [ABSTRACT FROM AUTHOR]

Improving the strength decrease caused by fungal metabolites is still an arduous task in the field of paper materials protection. A set of damaged Kangxi Dictionary from Qing Dynasty was chosen as samples in this work. The main goal of this work is to develop high-efficiency and eco-friendly media with the characteristics of antifungal and reinforcement, to preserve paper materials and continue the historical and scientific research value of cultural heritage. PHMG as an efficient antifungal was used in this work. For better behavior, the epoxy group of KH560 can be induced by the amino group in PHMG by ring opening reaction to form PHMG-KH560 colloidal complex. Spraying PHMG-KH560 on paper could establish Si-O-C bonding and increased the hydrogen bond between polymeric material and paper fibers, which simultaneously inhibited fungi and improved mechanical strength of the original paper, even after the artificial aging. PHMG-KH560 had certain antifungal activity against five fungi, such as Aspergillus versicolor, and Aspergillus Niger , and had better inhibitory effect on Cladosporium herbarum, Trichoderma viride , and Penicillium expansum. The ancient writing ink on the paper sprayed with PHMG-KH560 did not affect its visual beauty, which also indicated that the complex reagent was expected to be applied to the antifungal and reinforcement of paper materials. [ABSTRACT FROM AUTHOR]

• Artificial light radiation is a viable tool for paper documents bleaching. • Artificial light bleaching does not produce any physico-chemical change in paper. • Artificial light bleaching reduces the yellowing of paper in short and long term. • Paper is physico-chemical and optically deteriorated by hydrogen peroxide. This study offers a new tool to restorers to bleach paper documents: artificial light radiation (ALR). It is a controlled method that is an alternative to other highly aggressive procedures that have been applied to cellulose based media. Its main novelty is its intrinsic lighting characteristics which guarantee uniformity and avoid heating the paper. The results of testing this new tool were compared to those of bleaching with hydrogen peroxide (H 2 O 2). Each of the two methods was applied to five different types of widely used paper: Arches and Somerset (brands serving for engraving and digital printing), Ingres (drawing), press-type (magazines and newspapers) and Bible-type (historical documents). Once characterised by physico-mechanical, chemical and optical parameters (grammage, thickness, specular gloss, optical properties, air permeance, tensile properties, determining the pH of both surface and aqueous extracts), the different papers were bleached by the two methods according to pre-established criteria. Finally, to determine the evolution and effects of the two treatments, the papers were subjected to accelerated ageing. [ABSTRACT FROM AUTHOR]

Lining of canvases and paper artworks is a diffused conservation methodology developed to ensure the safe and long-term preservation of weakened supports. Lining systems are generally constituted by a new supporting material or a package of new materials glued to the original artefact. This paper reports on the study of the mechanical behaviour of four multi-layered paper and canvas composites, proposed as lining systems for a large drawing on paper: the "School of Athens" by Raffaello Sanzio, dated 1508. This masterpiece is the 1:1 preparatory cartoon for the wall-painting in the Vatican rooms. Uniaxial tensile testing has been employed in this study to characterize both the single layer materials and the overall mechanical behaviour of the composites. The mechanical tests have been performed before and after artificial ageing with high humidity regime. The complex testing protocol allowed selecting the best performing composite for the final lining, and to assess a safety threshold in terms of stress value for the framing and display of the restored artwork in the new showcase. The results constitute a quantitative evaluation of the different systems, and therefore they can effectively support the conservators' activity and methodological choices. [ABSTRACT FROM AUTHOR]

Abstract Books, prints, drawings, watercolours, engravings, as well as all other works of art based on paper, are very susceptible to fungal development. The excreted substances and the fungal structures themselves are often coloured and interfere with the readability of the artefacts, diminishing their artistic and monetary value. In order to direct cleaning methods for specific fungal stains on paper, the colourants (molecules) responsible for those stains need to be assessed. However, the literature regarding fungal stains on paper and colourants produced by those fungi is very dispersed and scarce. Therefore, the main objectives of this work were surveying the most common stains on paper, the colourants present on those stains and the main fungi responsible for these colourants' production. To achieve these goals, two different but complementary literature reviews were made: one on paper conservation literature, where fungal stains observed on paper cultural heritage are reported; and another survey on the chemical/food/pharmaceutical fields where colourants' molecules produced by fungi, that can colonise paper cultural heritage, are identified and studied in greater detail. This paper presents the first literature review on this subject. The results show that the fungal genera more frequently related with fungal stains on paper cultural heritage are Aspergillus (29%) and Penicillium (13%). The most common colour of the stains is brown (54%), caused by foxing in most of the cases. However, in the paper conservation literature, no consistent correlation has been observed between stain colour on paper/specific fungal species and colourants/chemical compounds. On the literature review regarding the use of fungal colourants for industrial/commercial purposes, the referred colourants can be mostly classified chemically as carotenoids and polyketides. Biosynthetically, most colourants produced by fungi are polyketide-based and representative classes may include chemical structures such as azaphilones, anthraquinones, hydroxyanthraquinones, naphthoquinones and other structures. From a total of 80 different colourants, the ones mostly produced by paper colonising fungi were polyketide quinones, namely the hydroxyanthraquinoid (HAQN) colourants. This review showed that the most commonly studied colours are yellow and red, followed by orange. The production of these colourants is often associated with the genera Aspergillus sp. and Penicillium sp. which are frequently found on stained paper. Overall, there is no doubt that colourants producing fungi are a serious problem to paper conservators, since there is a great variety of colourants produced by different species of fungi colonising paper. This review catalogues the fungal genera, species and excreted colourants mentioned in the literature as being responsible for staining paper cultural heritage. [ABSTRACT FROM AUTHOR]

The research aim was to determine the effectiveness of disinfection methods: thyme essential oil microatmosphere (TEO), silver nanoparticles misting (AgNPs), and low temperature plasma (LTP) by culture-dependent method and RNA analysis. In addition, we examined the influence of disinfection on mechanical and optical properties of paper from historical books with different levels of microbial contamination. All disinfection methods were generally bacteriostatic and fungistatic. The AgNPs misting method was more effective for bacterial inhibition ( R = 60–100%), than LTP ( R = 25–100%) and TEO ( R = 12–100%); all tested methods were less effective for fungi ( R = 0–99.8%). TEO exhibits a broader spectrum of fungicidal activity compared to AgNPs and LTP. The antimicrobial effectiveness depended on the area from where the microorganisms were isolated and their sensitivity to the active agent. A higher disinfection effectiveness was observed for books with higher levels of microbial contamination. RNA concentration was a good marker of antimicrobial activity of disinfection. RNA amount decreased by 95–100% after disinfection with LTP and TEO, and by 29–89% after AgNPs disinfection. Disinfection of paper from historical books with LTP, AgNPs and TEO did not significantly influence or have a positive effect on the mechanical and optical properties of paper from tested historical books. We show that LTP, TEO, and AgNPs can be used as microbiostatics, alternatively to the currently available methods. [ABSTRACT FROM AUTHOR]

Clotrimazole is a well-known antimycotic agent, listed in the World Health Organization List of essential medicines, with minimal health side effects acknowledged throughout a long certification period. In this study, clotrimazole in isopropanol was tested as a potential antifungal treatment for paper objects. The antifungal properties of this azole compound were evaluated against five of the most common fungal species affecting paper collections. The addition of a deacidifying agent, calcium hydroxide nanoparticles, resulted in a multipurpose formulation also aimed at neutralizing the deleterious effects of acids excreted by fungi. Clotrimazole showed antifungal activity against all tested fungal species and its effectiveness followed the ascending order: Chaetomium globosum < Cladosporium cladosporioides < Penicillium chrysogenum < Aspergillus niger < Penicillium corylophilum . The best relationship between minimal concentration and fungal inhibition was achieved for 0.05% clotrimazole. The impact of the tested formulation on paper preservation was evaluated in terms of pH, colour and folding endurance, using moist heat artificial ageing. Clotrimazole and calcium hydroxide nanoparticles protected the paper from acidification and loss of folding endurance in the long term, thus representing a non-aqueous alternative treatment for paper affected by fungi. [ABSTRACT FROM AUTHOR]

Historic works on paper, illuminated (painted) or unpainted manuscripts, and textiles are fragile and nearly impossible to sample. Non-invasive techniques such as visible microscopy, X-ray fluorescence, Raman, and reflectance spectroscopy are commonly used to determine the artist material present. Recently, nonlinear optical ultrafast pump-probe microscopy was shown to provide non-invasive, high-resolution mapping of pigments in historic paintings to investigate paint stratigraphy. In this paper, we combine our pump-probe contrast with nonlinear fluorescence and second-harmonic generation contrasts exhibited by fibrous supports composed of natural bio-materials (cellulose, collagen, or lignin). Hence, our multi-modal nonlinear microscope is able to simultaneously investigate pigments in conjunction with their support in three dimensions with micrometer-scale spatial resolution. Here we examine the utility of nonlinear pump-probe microscopy by studying a series of mock-up samples, including indigo-dyed cotton cloth, ultramarine blue painted on various types of paper, and papers painted with mixtures and layers of the two pigments. In each case we find that we can combine pump-probe pigment contrast with nonlinear optical fiber contrast to obtain spatial information that is otherwise unavailable to the conservator. [ABSTRACT FROM AUTHOR]

Cellulose oxidative and hydrolytical degradation is one of the greatest problems for the conservation of paper supports. To contrast these degradation processes, both deacidification and reduction of the oxidized functions are needed. Dealing with original documents, it is often impossible to perform the two mentioned treatments in aqueous solutions and in a distinct subsequent way, because of the fragility of the artifacts. After studying, in a separate way, an effective deacidifier (calcium propionate) soluble in ethyl alcohol and many reducers (boron complexes), able to act in different non-aqueous solvents, it was decided to test a simultaneous method of deacidification and reduction in ethanol. This paper presents the chemical-physical results obtained by applying simple deacidification and simultaneous deacidification-reduction on laboratory paper samples that were artificially aged and then re-measured after 10 and 15 years of natural aging. Results show that all alcoholic treatments are very effective: papers are stable also after a long period of both artificial and natural aging. [ABSTRACT FROM AUTHOR]

A severe decay process, catalyzed by acidity and metal ions, affects cellulose in historical manuscripts and books that contain iron gall inks. The inhibition of this process can be achieved by alkaline-earth nanoparticles dispersions in alcohols, which create a neutral environment in which both oxidation and depolymerization of cellulose are hindered. As a result of the degradation process, paper in historical manuscripts and books is fragile and very difficult to handle. A reinforcement intervention with gelatin and Japanese tissue could be used for the strengthening of historical manuscripts, even if this method could not prevent paper degradation due to iron gall inks. Therefore, a new method, combining a deacidification treatment based on calcium hydroxide nanoparticles and a reinforcement process using Japanese tissue has been developed and tested on mockups containing iron gall inks. The protective action arising from the combined treatment was evaluated by performing cellulose viscosimetric degree of polymerization (DPv) and pH measurements on artificially aged systems. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM-EDX) was used for the evaluation of calcium distribution from the deacidification agent within samples cross section. Determinations of DPv clearly showed that the degradation of untreated inked paper was significantly slowed down by the combined treatment. The method was also tested on original manuscripts from 16th and 18th century. SEM-EDX maps showed that the applied treatment, which raised the pH to an appropriate value, is homogenously distributed over the treated surfaces. [ABSTRACT FROM AUTHOR]

In this paper, members of three research teams, namely the Turfan Project of the Berlin Brandenburg Academy of Sciences and Humanities, the Berlin-based research project on pigments in Central Asian paper manuscripts, and the Hamburg-based project on the history and typology of Central Asian paper manuscripts, present some of the results of their cooperation. The investigated manuscripts belong to the Berlin Turfan Collection. On the basis of different examples the contribution of scientific methods to philological scholarship within a multidisciplinary approach is demonstrated. [ABSTRACT FROM AUTHOR]

Ground wood cellulose paper exhibits a practicable cleaning laser fluence window during middle-UV radiation processing. In this case, a minimum dose volume density should be applied. However, cleaning of bleached cellulose paper is accompanied by strong yellowing and destruction. The presence of charcoal graphite particulates shows substantial influence on the yellowing with increasing coverage. [ABSTRACT FROM AUTHOR]

This research evaluates the use of microblasting technique with powdered cellulose as a new tool for dry cleaning documents. Different cleaning tests were conducted on three documents with different properties following this new approach and the results were compared to those obtained with traditional dry cleaning with erasers. In order to assess changes caused to the supports, the treated documents were examined both before and after cleaning with optical and 3D stereomicroscopy, SEM-EDS and spectrophotometry. The results allow the conclusion that microblasting with powdered cellulose is a feasible technique to remove surface dirt or grime on paper documents. This research proves that the new use of the technique does not entail changes to the surface properties of the treated supports. Moreover, powdered cellulose is chemically stable and compatible with paper documents, preventing negative long-term effects derived from the presence of rubber residues that may remain in paper fibres when using erasers in dry cleaning treatments. [ABSTRACT FROM AUTHOR]