PABLO ANTONIO VASQUEZ SALVADOR

PABLO ANTONIO VASQUEZ SALVADOR

(Fonte: Lattes)

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Graduação em Engenharia Química - Escola Politécnica (1999), mestrado em ciências pela Universidade de São Paulo (2004) e doutorado em ciências pela Universidade de São Paulo e pela Washington University in St. Louis (2009). Pesquisador do Instituto de Pesquisas Energéticas e Nucleares IPEN. Professor e orientador em nível mestrado e doutorado do Programa de Pós-graduação em Tecnologia Nuclear da Universidade de São Paulo-USP. Responsável pela linha de pesquisa e aplicação da radiação ionizante para preservação de bens culturais. Consultor da Agência Internacional de Energia Atômica AIEA para preservação de Patrimônio Cultural utilizando radiação ionizante. Especialista na utilização da Radiação Ionizante na Esterilização e modificação de propriedades de materiais, radioesterilização, alimentos, polímeros, biomateriais, tecidos, implantes, etc. Qualificação de embalagens/produtos e boas práticas de esterilização, validação e controle do processo de irradiação. Pesquisa, desenvolvimento tecnológico, licenciamento e qualificação de irradiadores industriais e impacto ambiental. Pesquisa e desenvolvimento de sistemas de dosimetria industrial para irradiadores. Pesquisador responsável/coordenador do Irradiador Multipropósito de Cobalto-60 do Centro de Tecnologia das Radiações CETER/IPEN. Aplicação e estudos da radiação ionizante para modificação de propriedades físico-químicas de materiais. Experiência na área de Engenharia Química, com ênfase na aplicação de radioisótopos na indústria para controle de qualidade e otimização de processos: gamma scanning, traçadores radioativos, tomografia computadorizada, detectores cintiladores, sistemas de controle nucleônico. (Texto extraído do Currículo Lattes em 21 dez. 2021)

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Preservation of photographic and cinematographic films by electron-beam irradiation
2022 - VASQUEZ, P.A.S.; NAGAI, M.L.E.; OLIVEIRA, M.J.A.; OTUBO, L.; SOMESSARI, E.S.R.
The Nuclear and Energy Research Institute – IPEN through the Multipurpose Gamma Irradiation Facility and the Electron Beam Irradiation Facilities has disinfected several tangible cultural collections from the University of São Paulo – USP. Brazilian weather conditions added to the actions of insects and fungi promote biodegradation especially in cellulose-based materials. In this sense, ionizing radiation is an excellent alternative to the traditional preservation process mainly because the biocidal action. Electron beam irradiation also presents new possibilities for processing materials with greater speed, despite having limited penetration. Adequate storage of photographic and cinematographic materials is a challenge for 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 the effect of the electron beam irradiation on photographic and cinematographic films using an electron beam accelerator with energy of 1.5 MeV and beam power of 37.5 kW. Selected film samples were characterized by FTIR-ATR spectroscopy and FEGSEM-EDS microscopy. Samples were irradiated 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 electron beam radiation can be achieved safely applying radiation absorbed doses between 6 kGy to 10 kGy with no significant change or modification of main properties of the constitutive polymeric materials. Electron beam irradiation, due to the effect of crosslinking is presented as an alternative to treat films affected by “vinegar syndrome” applying absorbed dose of 80 kGy in order to increase shelf life of cultural heritage materials.
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.
Preservation and conservation of information contained in glassy materials from cultural collections with processing by ionizing radiation
2022 - NAGAI, MARIA L.; SALVADOR, PABLO A.V.
Glass-based photographic materials are commonly found in historical cultural heritage collections.Inadequate storage conditions for these materials lead to problems of biodeterioration, mainly by fungi. Processing by ionizing radiation with electron beam has a biocidal effect to combat fungal contamination. However, a known undesired effect on glassy materials is increased opacity which affects the readability of images on photographic glass negatives. In this way, the study proposes a methodology to minimize the darkening effects of the glasses that are subjected to irradiation. For this work, glass samples were subjected to irradiation with electron beams at doses of up to 25 kGy, under different controlled temperature conditions, and the effects analyzed by UV-visible spectrophotometry and colorimetry analysis.
Moving toward a sustainable conservation
2022 - VIEIRA, ANA C.D.; SALVADOR, PABLO A.V.; SANTOS, PAULO de S.
Most of the ethnographic collections present in traditional museums in Brazil were formed by collectors, purchases, donations and exchanges by large encyclopedic, naturalist museums, typical of the 19th century. It is in this context, the Museum of Archeology and Ethnology (MAE-USP) collection were constituted. The MAE has been made a big effort to guarantee their conservation. Preservation of tangible objects as well thousands of organic objects, composed of plant fibers, wood, skins, feathers, seeds and various materials, has always been challenging as they are prone to deterioration by biological agents such as insects, mold, bacteria and rodents. Chemical treatments are traditionally examples of actions to preserve many museum collections around the world. Since the 19th century, collectors and museum professionals have applied a variety of toxic substances through fumigations and direct applications trying to enhance the conservation. Although a well-intentioned practice, the application of pesticides to protect ethnographic objects could not predict the negative impact on the safety of those who would handle these objects in the future and by restricting the possibilities of using these collections by the descendants of their creators. Today, these contaminated objects cannot be touched without gloves or experienced by for example, indigenous groups. The current insertion of native communities in curatorial actions at museums has made it possible to renew the way in which these institutions work. At this moment, it is no longer plausible that a museum institution continues to carry out toxic treatments on funerary, sacred objects, human remains, among others. The possession and use of these objects transcend the museum’s borders and the possibilities of use must be considered in the perspective of the future. Due to the renewal of the theoretical parameters of the conservation discipline, the Integrated Pest Management policy is more suitable for museological institutions. Efforts to prevent damage have been more effective than just thinking about curative conservation. In addition, the need to develop a more sustainable present and future has led institutions to develop greener prevention policies, without the use of toxic products, respecting the environment and the user. In this scenario, since 2010, MAE-USP has abolished the use of pesticides to treat the collection. Since then, the institution has been dedicated to building a protocol to reduce risks related to infestations. This protocol encompasses, among other actions, the treatment of objects affected by biological agents and the preventive treatment of new objects through ionizing radiation. The use of ionizing radiation for the disinfestation of museum objects is a very safe process and has proved to be a great alternative to traditional methods of disinfestation that involve pesticides of high persistence and toxicity. For this reason, we have also worked to disseminate the technique among conservators. This work intends to share the actions carried out by MAE-USP in partnership with the Nuclear and Energy Research Institute (IPEN) to facilitate the treatment of ethnographic objects, as well as an important collaborator to make the conservation process at MAE more sustainable.
Ionizing radiation for preservation
2022 - VASQUEZ, PABLO A.; NAGAI, MARIA L.
The Nuclear and Energy Research Institute – IPEN through the Multipurpose Gamma Irradiation Facility and the Electron Beam Irradiation Facilities has disinfected several tangible cultural collections from the University of São Paulo – USP. Brazilian weather conditions added to the actions of insects and fungi promote biodegradation especially in cellulose based materials. In this sense, ionizing radiation is an excellent alternative to the traditional preservation process mainly because the biocidal action. Electron beam irradiation also presents new possibilities for processing materials with greater speed, despite having limited penetration. Adequate storage of photographic and cinematographic materials is a challenge for 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 the effect of the electron beam irradiation on photographic and cinematographic films using an electron beam accelerator with energy of 1.5 MeV and beam power of 37.5 kW. Selected film samples were characterized by FTIR-ATR spectroscopy and FEGSEM-EDS microscopy. Samples were irradiated 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 electron beam radiation can be achieved safely applying radiation absorbed doses between 6 kGy to 10 kGy with no significant change or modification of main properties of the constitutive polymeric materials. Electron beam irradiation, due to the effect of crosslinking is presented as an alternative to treat films affected by “vinegar syndrome” applying absorbed dose of 80 kGy in order to increase shelf life of cultural heritage materials.
Gamma radiation processing for disinfection of a 19th century photo album
2022 - NAGAI, M.L.E.; SANTOS, P.S.; PARRON, I.; LEE, F.M.; VASQUEZ, P.A.S.
A 19th century photo album was donated to the Hercule Florence Institute collection. After going through the quarantine, it was discovered that the album was contaminated by anobides. The album was sent for disinfestation treatment by ionizing radiation processing at IPEN. The dose applied was 3 kGy for the immediate eradication of the insects. Colorimetry analysis performed before and after irradiation found that treatment with ionizing radiation did not affect human color perception in the album and the photographs present.
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.
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.
A radiação ionizante como tecnologia para a inativação de vírus
2022 - ARAUJO, MARCIO M. de; BARREIRA, DAILI A.S.; BRITO, SUSYLEIDE G. de; SANTOS, PAULO de S.; BORRELY, SUELI I.; VASQUEZ, PABLO
Encontrar meios acessíveis e eficientes para inativação de patógenos, e, assim diminuir as consequências maléficas destes para a população, é uma questão que desafia os gestores públicos e a comunidade científica. Diante disso, nosso objetivo foi realizar uma revisão narrativa sobre o histórico do uso da radiação ionizante como tecnologia para inativação viral. Para isso, foram utilizados artigos disponíveis no Google Acadêmico, Scielo, PubMed e Periódicos da CAPES totalizando 35 artigos entre os anos de 1971 e 2022. A radiação ionizante é um método físico que destrói os ácidos nucleicos e inibi a replicação viral, mantendo sua imunogenicidade, sem requerer todas as etapas necessárias para desintoxicar as culturas provenientes de processos químicos, o que facilita o manuseio de antígenos em laboratório de segurança nível 2. Observamos que doses distintas para cada vírus dependente de condições relacionadas ao preparo da amostra, temperatura, umidade, falta de oxigênio, taxa da dose e penetração (estado físico do material); e também ao próprio vírus, como por exemplo o tamanho genômico. A radiorresistência presente nos vírus e esporos bacterianos também foi um fator relevante observado na literatura quanto a esterilização de materiais hospitalares por afetar algumas estruturas poliméricas do polipropileno em máscaras descartáveis, cuja a solução adotada foi a utilização da radiação não ionizante dependente do tempo, a ultra-violeta (UV – C). Portanto, apesar de ser um método mais custoso, a praticidade do processo que é continuo, sem residual e a segurança promovida pela não lisura da embalagem, permite a competitividade da radiação ionizante frente aos métodos existes tanto na esterilização de insumos quanto para produção de vacinas através da inativação viral.
Development of the mechanical system on a third-generation industrial computed tomography scanner in Brazil
2011 - CALVO, WILSON A.P.; MESQUITA, CARLOS H. de; SPRENGER, FRANCISCO E.; COSTA, FABIO E. da; SALVADOR, PABLO A.V.; CARVALHO, DIEGO V. de S.; HAMADA, MARGARIDA M.
The development of measurement geometry for medical X-ray computed tomography (CT) scanners carried out from the first to the fourth-generation. This concept has also been applied for imaging of industrial processes such as pipe flows or for improving design, operation, optimization and troubleshooting. Nowadays, gamma CT permits to visualize failure equipment points in three-dimensional analysis and in sections of chemical and petrochemical industries. The aim of this work is the development of the mechanical system on a third-generation industrial CT scanner to analyze laboratory gas absorption column which perform highly efficient separation, turning the 60Co, 137Cs or 192Ir sealed gamma-ray source and the NaI(Tl) multidetector array. It has also a translation movement along the column axis to obtain as many slices of the process flow as needed. The mechanical assembly for this third-generation industrial CT scanner is comprised by strength and rigidity structural frame in stainless and carbon steels, rotating table, source shield and collimator with pneumatic exposure system, spur gear system, translator, rotary stage, drives, and stepper motors. The use of suitable spur gears has given a good repeatability and high accuracy in the degree of veracity. The data acquisition boards, mechanical control interfaces, software for movement control and image reconstruction were specially development. This third-generation industrial CT scanner has obtained good spatial resolution and images. The filtered back projection (FBP) tomographic reconstruction algorithm used has shown a faster convergence. The mechanical system presented a good performance in terms of strength, rigidity, accuracy and repeatability with great potential to be used for education or program dedicated to training chemical and petrochemical industry professionals and for industrial process optimization in Brazil.