PAULO DE SOUZA SANTOS
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Artigo IPEN-doc 29100 Silver nanoparticles-based hydrogels synthetized by ionizing radiation for cleaning of tangible cultural heritage surfaces2022 - OLIVEIRA, MARIA J.A.; OTUBO, LARISSA; PIRES, ADRIANA; BRAMBILLA , RODRIGO F.; CARVALHO, ANA C.; SANTOS, PAULO S.; OLIVEIRA NETO, ALMIR; VASQUEZ, PABLOThe 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.Artigo IPEN-doc 29099 Effects of ionizing radiation decontamination on botanical collections in herbaria2023 - LIMA, LENI M.P.R.; KODAMA, YASKO; BAITELLO, JOAO B.; OTUBO, LARISSA; SANTOS, PAULO de S.; VASQUEZ, PABLO A.S.Herbaria collections are very sensitive to attacks from microorganisms and insects. Therefore, preservation strategies and appropriate treatments are essential to manage these artifacts. Decontamination by ionizing radiation has become an effective strategy to preserve cultural heritage objects and archived materials, achieving excellent results. Therefore, this work aimed to study the effects of Co-60 gamma radiation on botanical collections. To accomplish this, samples of exsiccates, including botanical pressed and dehydrated specimens from Asteraceae and Solanaceae families, collected on diferentes dates were selected from the Dom Bento José Pickel Herbarium (SPSF), located in São Paulo (Brazil). Irradiation was performed at the Multipurpose Gamma Irradiation Facility at IPEN, applying absorbed doses of 1 kGy, 6 kGy and 10 kGy. Gamma radiation effect was analyzed using colorimetry with CIELAB color space scale, scanning electron microscopy (SEM) and attenuated total reflectance with Fourier transform infrared (ATR-FTIR) spectroscopy. Results showed no significant colorimetric changes, or changes in the morphological properties of samples, indicating that this decontamination method can be used as an alternative treatment to eliminate insects and micro-fungi of botanical collections without the use of toxic substances.Artigo IPEN-doc 27825 Gamma and electron beam irradiation effects for conservation treatment of cellulose triacetate photographic and cinematographic films2021 - 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”.