PAULO DE SOUZA SANTOS

PAULO DE SOUZA SANTOS

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New trends and applications of ionizing radiation for preservation of cultural heritage tangible materials
2022 - VASQUEZ, PABLO A.S.; VIEIRA, ANA C.; LIMA, LENI; NAGAI, MARIA L.; KODAMA, YASKO; OLIVEIRA, MARIA J.; SANTOS, PAULO
Disinfection of cultural heritage artefacts and archived materials using ionizing radiation has been successfully applied and accepted by the Brazilian conservation and preservation institutions and community in recent years. Several works of art, museum collections artefacts, books, manuscripts, drawings, archive documents, musical instruments, ethnographic objects, archaeological findings and natural history collections have been decontaminated. Several research studies have been developed addressing the behaviour of cellulosic based materials treated with the ionizing radiation. However, many Brazilian collections have objects made from the most diverse constitutive materials and these are affected by biodeterioration. In order to the effective decontamination of the most diverse types of objects there was a need to establish protocols for care of institutions and individuals carrying cultural and historical collections and for the effective processing by ionizing radiation in the facilities respecting the ethical principles of conservation and restoration covering activities from the problem detection to the final cleaning. Additionally, ionizing radiation has allowed the development of innovative nanostructured cross-linked materials, with applicability in cleaning delicate surfaces. This work presents the most recent results of the effect of ionizing radiation on morphology and physicochemical properties of photographic and cinematographic films, featherwork and botanical collections – exsiccate; as well as the protocols developed as a practical guide for conservatives and professionals of the irradiation for treatment of tangible objects. Preliminary results of nanostructured cross-linked polymeric hydrogels for cleaning surface of artworks obtained by ionizing radiation are also presented. The IAEA sponsored projects have helped to increase the acceptance of nuclear technology by the Brazilian society, especially by the community of restorers, curators and conservators of material cultural goods. The research developed and disseminated with the support of IAEA contributes to the understanding that the cultural heritage is the legacy of physical artefacts and intangible attributes of a group or society that are inherited from past generations, maintained in the present and restored for the benefit of future generations.
Silver nanoparticles-based hydrogels synthetized by ionizing radiation for cleaning of tangible cultural heritage surfaces
2022 - OLIVEIRA, MARIA J.A.; OTUBO, LARISSA; PIRES, ADRIANA; BRAMBILLA , RODRIGO F.; CARVALHO, ANA C.; SANTOS, PAULO S.; OLIVEIRA NETO, ALMIR; VASQUEZ, PABLO
The surfaces of the works of art are one of their most important parts since they interact directly with the observer's perception. On the other hand, they are also in direct contact with physical, chemical and biological agents that can induce degradation and signs of aging. Dust deposits, stains and aged layers of protection can degrade, causing irreversible damage to works of art. In this way, the removal of undesirable materials from artistic surfaces is essential to preserve cultural heritage articles. The aim of this work was to develop silver nanoparticles-based hydrogels and to study the behavior regarding solvent concentration, stability and ability to clean dirt samples based on paper and canvas. The hydrogels were synthesized (reticulated) by gamma rays having the simultaneous formation of silver nanoparticles (AgNP) in the same process. The samples were characterized by swelling tests, attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, differential scanning calorimetry (DSC), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and optical microscopy (OM). The results showed the removal of dirt from the paper samples, as well as the softening of the dirt from the canvas, without leaving residues and without affecting the integrity of the art works submitted to treatment.
Development of methodologies for decontamination, reuse and improvement of the properties of respiratory protective equipment using ionizing radiation
2020 - VASQUEZ, P.A.S.; MORAIS, F.; LIMA, F.S.; SANTOS, P.S.; MORAES, O.; ARTAXO, P.; JOHN, V.M.; NAGAI, M.L.E.; OLIVEIRA, M.J.A.; CATALANI, L.H.; KODAMA, Y.; OTUBO, L.
Gamma and electron beam irradiation effects for conservation treatment of cellulose triacetate photographic and cinematographic films
2021 - NAGAI, MARIA L.E.; SANTOS, PAULO de S.; OTUBO, LARISSA; OLIVEIRA, MARIA J.A.; VASQUEZ, PABLO A.S.
Photographic and cinematographic films of cellulose triacetate safeguarded in historical and cultural institutions are often contaminated by fungi when stored in inadequate conditions of humidity and temperature. The presence of fungi affects the image contained in the films, accelerates the process of biodeterioration and represents a risk to the health of people working with contaminated materials. In addition, another common physicochemical degradation affecting cellulose triacetate films causing deacetylation of polymer chain is called “vinegar syndrome”. Considering the dose interval established for the disinfection of cultural heritage materials, in this work the effects of irradiation with gamma rays and electron beam on photographic and cinematographic films of cellulose triacetate were evaluated. Additionally, the thermal stability behavior of the films and the feasibility of crosslinking of CTA films were investigated. Film samples were selected and characterized by FTIR-ATR spectroscopy. Irradiated samples by gamma rays and electron beam with radiation absorbed doses between 6 kGy and 200 kGy were examined by FEGSEM microscopy, UV–Vis spectrophotometry and differential scanning calorimetry (DSC). The results showed that disinfection by gamma and electron beam irradiation, in the dose range of 6 kGy–10 kGy, does not change or modification of main properties of the constitutive materials of photographic and cinematographic films. The applied dose of 50 kGy, both gamma rays and electron beam, indicated a crosslinking effect on the films and can be considered a possibility for the treatment of films affected by the “vinegar syndrome”.
Ionizing radiation for the preservation and conservation of photographic and cinematographic films
2019 - NAGAI, MARIA L.E.; SANTOS, PAULO S.; OTUBO, LARISSA; OLIVEIRA, MARIA J.A. de; VASQUEZ, PABLO A.S.
The Nuclear and Energy research Institute – IPEN-CNEN/SP through the Multipurpose Gamma Irradiation Facility has treated several bibliographical collections of Sao Paulo University-USP for disinfestation and disinfection of contaminated materials with insects and fungi. In this sense, gamma radiation from cobalt-60 is an excellent alternative tool to the traditional preservation process mainly because the biocidal action. Disinfection using gamma radiation for cultural heritage materials has been widely applied around the world in the last decades. Adequate storage of photographic and cinematographic materials is a challenge for conservation experts from preservation institutions. Contamination by fungi is one of leading causes of problem in this kind of collections. In addition, another common physicochemical degradation affecting cellulose triacetate films causing deacetylation of polymer chain is called “vinegar syndrome”. In this work are presented results of effect of ionizing radiation on photographic and cinematographic films. Selected films were characterized by FTIR-ATR spectroscopy and FEGSEM-EDS microscopy. Samples were irradiated by gamma rays with absorbed dose between 2 kGy and 200 kGy. Irradiated samples were analyzed by UV-vis spectrophotometry, FEGSEM, thermogravimetric analysis (TG) and differential scanning calorimetry (DSC). Results showed that disinfection by gamma rays can be achieved safely applying radiation absorbed doses between 6 kGy and 10 kGy with no change or modification of main properties of the constitutive polymeric materials. Gamma rays due to the effect of crosslinking is presented as an alternative to treat films affected by “vinegar syndrome” applying absorbed dose of 50 kGy in order to increase shelf life of cultural heritage materials.
Preservation of photographic and cinematographic films by gamma radiation- preliminary analyses
2017 - NAGAI, MARIA L.E.; SANTOS, PAULO S.; OTUBO, LARISSA; OLIVEIRA, MARIA J.A.; VASQUEZ, PABLO A.S.
Brazilian weather conditions affect directly tangible materials causing deterioration notably getting worse by insects and fungi attack. In this sense, gamma radiation provided from the cobalt-60 is an excellent alternative tool to the traditional preservation process mainly because it has biocidal action. Radiation processing using gamma radiation for cultural heritage materials for disinfection has been widely used around the world in the last decades. Many cultural heritage objects especially made on paper and wood were studied in scientific publications aiming mechanical, physical and chemical properties changes. Over the last fifteen years, the Multipurpose Gamma Irradiation Facility of the Nuclear and Energy Research Institute located inside the Sao Paulo University campus has been irradiated many collections of archived materials, books, paintings and furniture. Adequate storage of photographic and cinematographic materials is a challenge for conservators from preservation institutions. Contamination by fungi is one of leading causes of problem in photographic and cinematographic collections. Several Sao Paulo University libraries have been affected by fungi in their photographic and cinematographic collections making it impossible to research on these materials either manipulate them for health and safety reasons. In this work are presented preliminary results of effects of the ionizing radiation in photographic and cinematographic films. Selected film samples made on cellulose acetate were prepared and characterized by FTIR-ATR spectroscopy. Samples were irradiated by gamma rays with absorbed dose between 2 kGy and 50 kGy. Irradiated samples were analyzed by UV-VIS spectroscopy and electron microscopy techniques. Results shown that disinfection by gamma radiation can be achieved safely applying the disinfection dose between 6 kGy to 15 kGy with no significant change or modification of main properties of the constitutive materials.