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Biocatalyst engineering applied to the synthesis of fatty xylose esters derived from the C-5 fraction of lignocellulosic residues
(Universidade Federal de São Carlos, 2026-03-16) Souza, Leonardo de; Tardioli, Paulo Waldir; https://lattes.cnpq.br/0808991927126468; https://lattes.cnpq.br/5597908810221416; Perna, Rafael Firmani; Guimarães, José Renato; Cansian, Ana Bárbara Moulin; Bernardo, André; https://lattes.cnpq.br/7591460969135629; https://lattes.cnpq.br/4550733668734212; https://lattes.cnpq.br/2791829789886693; https://lattes.cnpq.br/5705402824877708
The growing demand for sustainable, low-environmental-impact surfactants has driven the development of biotechnological routes capable of converting renewable feedstocks into high-value products. In this context, the enzymatic synthesis of xylose fatty acid esters stands out as a promising alternative, particularly due to its potential do valorize the C5 fraction of lignocellulosic biomass, which remains underexploited in industrial applications. However, challenges related to low solubility of xylose, the limited stability of biocatalysts, and reduced catalytic efficiency in non-conventional media still hinder the implementation of these processes. This thesis aimed to develop and evaluate integrated strategies for the enzymatic production of xylose esters, addressing key gaps in biocatalyst engineering, reaction medium selection, and the use of biomass-derived feedstocks. Initially, the state of the art in the enzymatic synthesis of xylose esters was assessed through systematic literature mapping, enabling the identification of recurring strategies, limitations, and opportunities related to catalysts, acyl group donors, solvents, and downstream processing. The results indicated that lipases are the preferred biocatalysts for xylose ester synthesis. Additionally, solvent selection was identified as a crucial factor, with oleic acid, lauric acid, and methyl and vinyl esters being the most commonly employed acyl donors. Subsequently, post-treatment strategies were investigated for the commercial biocatalyst Novozym® 435. The results demonstrated that coating with polyethyleneimine followed by crosslinking with glutaraldehyde yielded more robust biocatalysts, resulting in a 2.3-fold increase in oleic acid conversion when a deep eutectic solvent was used to solubilize xylose, and a 1.5-fold increase when methyl ethyl ketone and tert-butanol were employed. In addition, post-treatment improved operational stability over successive reaction cycles, with approximately 75% retention of catalytic activity after five reuse cycles. A key advancement of this work was the use of a chloride–xylose deep eutectic solvent, which significantly enhanced xylose solubility, reaching concentrations above 600 mM, substantially higher than those observed in conventional organic solvents (7 mM in methyl ethyl ketone and 60 mM in tert-butanol). This increased solubility directly improved enzymatic performance, enabling higher conversion rates and high selectivity toward xylose monoesters. In parallel, the effects of different immobilization protocols and metal modification of the lipase Eversa® Transform 2.0 were evaluated, revealing variations in catalytic activity, thermal stability, and specificity. Spectroscopic analyses confirmed conformational changes in the immobilized enzymes, allowing correlation between immobilization pH and the observed hydrolytic activity and catalytic specificity. Finally, the feasibility of producing xylose esters from sugarcane bagasse was demonstrated through the integration of biomass pretreatment and enzymatic conversion steps. Pretreatment with acetic acid and hydrogen peroxide resulted in a fourfold increase in sugar release during enzymatic hydrolysis with xylanases, compared to untreated bagasse. Biocatalysts prepared by immobilizing Eversa® Transform 2.0 at pH 5 in the presence of 100 mM NaCl, followed by metal modification with MgCl₂, were evaluated. The non-metal-modified biocatalyst exhibited superior performance, achieving 15% oleic acid conversion and 63% xylose conversion. Overall, the modulation of biocatalyst properties through immobilization and post-treatment strategies, the use of deep eutectic solvents in xylose esterification, and the application of xylose derived from sugarcane bagasse significantly advance the field of applied biocatalysis for sugar ester synthesis. This findings provide concrete perspectives for the development of sustainable industrial routes for biosurfactant production.
Quando o meu eu é uma extensão do outro: uma etnografia sobre o assistencialismo prisional da Igreja Universal
(Universidade Federal de São Carlos, 2026-03-16) Ruiz, Mônica Pereira; Ohlson, Olof Kjell Oscar; https://lattes.cnpq.br/4293686059879161; https://orcid.org/0000-0002-1819-9658; https://lattes.cnpq.br/3888652607357059; https://orcid.org/0009-0007-7993-4269; Ohlson, Olof Kjell Oscar; Potechi, Bruna; Lehmann, David; https://lattes.cnpq.br/4293686059879161; https://lattes.cnpq.br/0123931942250225; https://orcid.org/0000-0003-4709-0886
This dissertation analyzes the prison-based social assistance work of the Universal Church of the Kingdom of God (IURD) through its social outreach group “Universal in Prisons” (UNP), active in the Campinas region and surrounding areas. Based on an ethnography conducted among the group’s volunteers, combining participant observation and interviews, it seeks to understand the functioning of UNP through its social practices and the meanings attributed by the participants themselves. Although the literature on the IURD’s social engagement tends to emphasize the theology of spiritual warfare and institutional discourses as key explanatory frameworks, this research prioritizes the volunteers’ perspectives on their own activities, highlighting that the group is composed of individuals who have experienced incarceration, either directly or through the experience of family members and close acquaintances. The findings show that the experience of imprisonment is not limited to a biographical fact, but constitutes a fundamental element in the production of meanings that guide action within UNP, shaping volunteers’ religious and social engagement.
Mediações visuais no ensino de ciências: proposta de taxonomia para a análise de artefatos
(Universidade Federal de São Carlos, 2026-03-16) Luz, Luís Gustavo; Fernandes, Hylio Laganá; https://lattes.cnpq.br/1315602045624096; https://orcid.org/0000-0003-0922-867X; https://lattes.cnpq.br/2951486088322705; https://orcid.org/0000-0002-9917-1592; Silva, Maria Aparecida Alves da; Andraus, Gazy; Lupetti, Karina Omuro; Marques, Sílvio César Moral; https://lattes.cnpq.br/9904462066832764; https://lattes.cnpq.br/0256950026952623; https://lattes.cnpq.br/5198051111079064; https://lattes.cnpq.br/6047434055828372; https://orcid.org/0000-0002-5731-716X; https://orcid.org/0000-0002-6580-5550; https://orcid.org/0000-0003-0808-0677; https://orcid.org/0000-0002-9424-9442
The study proposes a taxonomy intended to guide the analysis of instructional visual artefacts for science education, in a context in which sharing, creating, and editing images have become more common, while the distance grows between tool use and an understanding of the processes that underpin graphic and interpretive choices. The scope privileges artefacts produced with communicative intent, connected to science teaching and science communication, and assumes that strengthening repertoires for visual reading and visual production becomes necessary as the means of creation, editing, and circulation grow more complex. To support a unified analytical language, the work brings together contributions from diverse fields that make it possible to describe how artefacts organize information, structure relationships, and guide interpretive paths. It integrates studies from the psychology of perception and art theory, which emphasize perception as an organizing principle and offer categories for describing thought through form. It also draws on cartography and data visualization, with proposals for systematizing visual variables and modes of graphic construction, alongside criteria of visual economy and graphic integrity derived from statistics applied to communication. Approaches that treat the image as a contested field are also included, discussing the polysemy of the term “image,” media hybridity, and institutional tensions surrounding these concepts. Completing this set are perspectives from semiotics and visual rhetoric, which describe operations between the plastic and iconic layers of the sign; contributions on persuasive language in applied contexts that distinguish formal patterns and semantic deviations in terms of cognitive costs; and a socio-semiotic grammar focused on compositional choices, credibility, and ideological effects. In addition, the study considers models oriented toward structural unification and visualization design, including empirical dimensions for characterizing graphical abstracts, recursive descriptions of the syntax of the graphic object, and a philosophical roadmap for understanding how models can say something about the world. The Peircean framework contributes universal categories—Firstness, Secondness, and Thirdness—along with the triadic definition of the sign and its organization into classes, and it supports the connection to science education through hypoicons and their sublevels—image, diagram, and metaphor—highlighting the role of the diagram in reasoning and in making relationships explicit, as well as the importance of collateral knowledge for images and metaphors to function as interpretable statements. On this basis, concepts are selected to create a basic taxonomy as an analytical instrument aimed at reading and producing visual artefacts used in science education, organized into the following taxons: Diagrammatic Space, Diagrammatic Multiplicity, Diagrammatic Relation, Diagrammatic Composition, Diagrammatic Navigation, Temporal–Diagrammatic Stability, Diagram Interactivity, Access to the Object, and Type–Specimen. Finally, taxonomy is applied to a range of objects through detailed analyses in order to observe the behavior of the taxons, discuss results, identify strengths and weaknesses, and reflect on criteria for evaluating the procedure.