PAULO DE SOUZA SANTOS

PAULO DE SOUZA SANTOS

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Effects of ionizing radiation decontamination on botanical collections in herbaria
2023 - 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.
Effect of ionizing radiation on the color of botanical collections - exsiccata
2021 - LIMA, L.M.P.R.; KODAMA, Y.; OTUBO, L.; SANTOS, P.S.; VASQUEZ, P.A.
Conservation and preservation strategies are essential to manage botanical collections specially for dried herbarium specimens also known as exsiccates, usually referring to a set of identified specimens belonging to taxa and distributed among all herbaria around the world. Particularly, these collections are very sensitive to the attack of fungi and insects. In recent years, disinfection by ionizing radiation has become an effective strategy to preserve cultural heritage objects and archived materials with excellent results. In this work, the effects on color properties of gamma radiation on exsiccates samples were studied. Thus, two exsiccates, botanical pressed and dehydrated samples were selected from the Dom Bento José Pickel Herbarium (SPSF), situated at São Paulo (Brazil). These samples comes from Asteraceae and Solanaceae families and were collected in 1946 and 1984. The irradiation was performed at the Multipurpose Gamma Irradiation Facility at IPEN applying absorbed doses of 1 kGy, 6 kGy and 10 kGy, which are values of absorbed dose for disinfestation and disinfection. Results were analyzed using colorimetry with CIELAB color space scale and scanning electron microscopy. The results showed that there were no significant changes on colorimetric morphological properties of the samples.
Irradiation protocol for cultural heritage conservation treatment
2021 - NAGAI, M.L.E.; SANTOS, P.S.; VASQUEZ, P.A.S.
Ionizing radiation supplied by cobalt-60 is an excellent alternative tool to the traditional process of decontamination of cultural and historical materials, mainly because of its biocidal action. Analyzing the occurrence of requests for treatment materials from cultural institutions with ionizing radiation for fungal decontamination in the Multipurpose Gamma Irradiation Facility of the Nuclear and Energy Research Institute - CTR/IPEN, there was a need to establish a protocol for the care of institutions and individuals carrying cultural and historical collections. The study proposal was the establishment an efficient and reproducible model of an irradiation protocol for the treatment of cultural heritage materials in industrial irradiators, respecting the ethical principles of conservation and restoration activities. The objective of the protocol is to be a practical guide, from the detection of the problem to the final cleaning, so that conservator-restorers and professionals of the irradiation can act in a collaborative and objective way to reach the objective of the treatment.
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”.
The effect of gamma radiation on the structure of graphene oxide and graphene oxide functionalized with amino-PEG
2019 - SOARES, J.J.S.; JACOVONE, R.M.S.; SANTOS, P.S.; ZAIM, M.H.; FARIA, D.L.A.; SAKATA, S.K.
Covalent functionalization of graphene oxide (GO) with polyethylene glycol (PEG) has been widely used in drug delivery systems. This nanocomposite exhibits excellent stability in the presence of high concentrations of salts and proteins and shows low toxicity compared to its raw form. However, it must be sterilized prior to use in medical devices, and for this purpose, the gamma irradiation shows a promising option. Sterilization by ionizing energy through gamma rays, generated by Cobalt-60 self-disintegration, consists in exposing the materials to short electromagnetic waves. The irradiation process provides substantial advantages when compared to thermal and chemical processes, such as, more precise control of the process, lower energy consumption, and less environmental pollution. In this work the effects of gamma radiation on GO and GO functionalized with amino-PEG (GO-PEG-NH2) irradiated with doses (15, 25, 35 and 50 kGy) at rate dose of 7.3 kGy.h-1 were evaluated. The analyses were performed by Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy. The results showed that gamma radiation up to 50 kGy did not cause any defects on the nanomaterials.
Study of free radicals in gamma irradiated cellulose of cultural heritage materials using Electron Paramagnetic Resonance
2016 - KODAMA, YASKO; RODRIGUES JUNIOR, ORLANDO; GARCIA, RAFAEL H.L.; SANTOS, PAULO de S.; VASQUEZ, PABLO A.S.
Main subject of this article was to study room temperature stable radicals in Co-60 gamma irradiated contemporary paper using Electron Paramagnetic Resonance spectrometer (EPR). XRD was used to study the effect of ionizing radiation on the morphology of book paper. SEM images presented regions with cellulose fibers and regions with particles agglomeration on the cellulose fibers. Those agglomerations were rich in calcium, observed by EDS. XRD analysis confirmed presence of calcium carbonate diffraction peaks. The main objective of this study was to propose a method using conventional kinetics chemical reactions for the observed radical formed by ionizing radiation. Therefore, further analyses were made to study the half-life and the kinetics of the free radical created. This method can be suitably applied to study radicals on cultural heritage objects.