Search

openaire: EC/H2020/788489/EU//BioELCell A major challenge exists in the preparation of scaffolds for bone regeneration, namely, achieving simultaneously bioactivity, biocompatibility, mechanical performance and simple manufacturing. Here, cellulose nanofibrils (CNF) are introduced for the preparation of scaffolds taking advantage of their biocompatibility and ability to form strong 3D porous networks from aqueous suspensions. CNF are made bioactive for bone formation through a simple and scalable strategy that achieves highly interconnected 3D networks. The resultant materials optimally combine morphological and mechanical features and facilitate hydroxyapatite formation while releasing essential ions for in vivo bone repair. The porosity and roughness of the scaffolds favor several cell functions while the ions act in the expression of genes associated with cell differentiation. Ion release is found critical to enhance the production of the bone morphogenetic protein 2 (BMP-2) from cells within the fractured area, thus accelerating the in vivo bone repair. Systemic biocompatibility indicates no negative effects on vital organs such as the liver and kidneys. The results pave the way towards a facile preparation of advanced, high performance CNF-based scaffolds for bone tissue engineering.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES A tese trata de uma investigação sobre como se deu a recepção da teoria queer e, especialmente, da obra de Judith Butler no Brasil. Para tanto, foi elucidado como os conceitos explorados por Butler foram importantes para o desenvolvimento dos estudos queer e como a sua incorporação no país tornou possível conceber novos olhares sobre categorias de análise para as Ciências Sociais brasileiras. Metodologicamente, o trabalho é de caráter bibliográfico e adota uma postura cartográfica baseada nas contribuições de Deleuze & Guattari (1995), Guattari & Rolnik (1996), Rolnik (2011), Eduardo Passos, Vírginia Kastrup e Liliana da Escóssia (2009) a fim de desvelar as possibilidades de antropofagização do pensamento de Butler e da teoria queer no Brasil. A pesquisa possibilitou, por meio de uma exploração no Banco de Teses e Dissertações da CAPES e na Plataforma Scielo, traçar um mapa rizomático dos estudos queer e butlerianos em solo brasileiro e visibilizar produções originais que dialogaram com o queer no país de forma pioneira. Com isso, a tese visa contribuir para o debate sobre como as possíveis tensões, rupturas e problemáticas propostas pelo pensamento de Butler e pelos estudos queer podem ser relevantes para as discussões sobre relações de gênero, sexualidades, violência, precariedade, vulnerabilidade e reconhecimento. The thesis deals with an investigation about how queer theory was received and, especially, Judith Butler's work in Brazil. Therefore, it was elucidated how the concepts explored by Butler were important for the development of queer studies and how their incorporation in the country made it possible to conceive new perspectives on analysis categories for Brazilian Social Sciences. Methodologically, the work is bibliographic and adopts a cartographic posture based on the contributions of Deleuze & Guattari (1995), Guattari & Rolnik (1996), Rolnik (2011), Eduardo Passos, Vírginia Kastrup and Liliana da Escóssia (2009) in order to unveil the possibilities of anthropophagy of Butler's thought and queer theory in Brazil. The research made it possible, by means of an exploration in the Bank of Theses and Dissertations of CAPES and in the Scielo Platform, to draw a rhizomatic map of queer and butlerian studies in Brazilian soil and to show original productions that dialogued with queer in the country in a pioneering way. Thus, the thesis aims to contribute to the debate on how the possible tensions, ruptures and problems proposed by Butler's thinking and by queer studies can be relevant to discussions on gender relations, sexualities, violence, precariousness, vulnerability and recognition.

The preparation of inclusion complexes based on α-cyclodextrin (α-CD) and oligo(ethylene glycol) methyl ether methacrylate (OEGMA) was investigated aiming to reveal complexation particularities and thermodynamic and kinetic aspects as a function of the oligomer architecture. Small-angle X-ray scattering and isothermal titration calorimetry measurements revealed that oligomer molecular weight controls both the kinetics and thermodynamics of inclusion. Unlike linear ethylene glycol polymers, OEGMA groups possess a methacrylate group, which seems to act as a stopper, affecting their mode of complexation. Nuclear magnetic resonance spectra and relaxation measurements support the fact that methacrylate groups lie outside the α-CD ring and that a full sequential complexation of the oligomer ethylene oxide groups is not observed. These results allied to the temperature sensitivity of these oligomers and enable possible routes for chemical modifications and design of new stimuli-responsive materials.

International audience; Nanocellulose has generated a great deal of interest as a source of nanometer-sized reinforcement, because of its good mechanical properties. In the last few years, nanocellulose has also attracted much attention due to environmental concerns. This review presents an overview of recent developments in this area, including the production, characterization, properties, and range of applications of nanocellulose-based biodegradable polymers, thermoplastic polymers, and porous nanocomposites. After explaining the unique properties of nanocellulose and its various preparation techniques, an orderly introduction of various nanocellulose-reinforced biodegradable polymers such as starch, proteins, alginate, chitosan, and gelatin is provided. Subsequently, the effects of nanocellulose on the properties of thermoplastic polymers such as polyamides, polysulfone, polypropyrol, and polyacronitril are reported. The paper concludes with a presentation of new finding and cutting-edge studies on nanocellulose foam and aerogel composites. Three different types of aerogels, i.e., pristine nanocellulose-based aerogels, modified nanocellulose-based aerogels, and nanocellulose-based templates for aerogels, are discussed, as well as their preparation techniques and properties. In the case of foam composites, the research focus has been on two major preparation techniques, i.e., solvent-mixing/foaming and melt-mixing foaming, their respective challenges, and the properties of the final composites. In some cases, a comparison study between cellulose nanocrystals and cellulose nanofiber-reinforced biodegradable polymers, thermoplastics, and porous nanocomposites was carried out. Considering the vast amount of research on nanocellulose-based composites, special emphasis on such composites isprovided at the end of the review.

In this work, we explore the architecture of highly porous foams based on cellulose nanofibers (CNFs) prepared by using cationic surfactants (e.g., C12TAB, C14TAB, and C16TAB) as modifying agents. The addition of surfactants to CNF suspensions led the nanoparticles surface to be covered by these molecules, reducing the ζ-potential from −35 to −8 mV, which, together with hydrophobic interactions of adsorbed surfactants, causes CNF flocculation. After freeze-casting and lyophilization, mechanical properties and pores structure of the low-density foams obtained (15.6–30.9 mg cm−3) proved to be strongly dependent on nanofibers agglomeration degree. The primary causes of such dependence could not be observable by scanning electron microscopy but were found to be very significant on X-ray microtomography analysis. Total porosity, pore-size, and wall thickness of the foams were calculated and related to the surfactant chain size. Surface areas from 4.7 to 48.6 m2 g−1, obtained by n-decane adsorption, are reported.

The influence of ice-crystals growing direction over the organization of cellulose nanofibers as freeze-casted foams is reported. This tuning was achieved by changing the metallic (copper) area of the sample molds which altered the freezing-front behavior, causing an oriented foam structure in certain directions. This orientation imparted different microarchitectures to the foams, leading to different pores sizes and wall thicknesses which could be characterized by advanced image techniques based on microtomography. As consequence, mechanical properties, such as compression modulus, have changed. In this study, a statistical approach is used to validate all the results obtained.

International audience; Research on nanocellulose has significantly increased over the past few decades, owing to the various attractive characteristics of this material, such as renewability, widespread availability, low density, excellent mechanical properties, economic value, biocompatibility, and biodegradability. Nanocellulose categorized into two main types, namely cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs). In this review, we present the recent advances made in the production of CNFs and CNCs. In addition to the conventional mechanical and chemical treatments used to prepare CNFs and CNCs, respectively, other promising techniques as well as pretreatment processes have been also proposed in recent times, in an effort to design an economically efficient and eco-friendly production route for nanocellulose. Further, while the hydrophilic nature of nanocellulose limits its use in polymeric matrices and in some industrial applications, the large number of hydroxyl groups on the surface of nanocellulose provides a suitable platform for various kinds of modification treatments. The various chemical and physical surface treatment procedures reported for nanocellulose have been reviewed in this paper. Finally, in this review, we summarize the life cycle assessment studies conducted so far on nanocellulose, which quantify the environmental impact of nanocellulose products. The current paper is a comprehensive review of the recent literature on nanostructured cellulose.

Este artigo tem como objetivo realizar um diálogo entre as ponderações de Michel Foucault, Judith Butler e Berenice Bento sobre a sanção normalizadora em corpos vistos como “estranhos” por não respeitarem as normas de gênero baseadas no modelo heterossexual. Neste texto, cuja reflexão teórica está ancorada nos estudos queer, procuramos também pensar a noção de corpo e materialidade com a finalidade de apresentar a intersexualidade como condição corpórea que desmonta a “fantasia” de corpos dimórficos. Pôde-se concluir a partir do debate sobre o tema da normalização que o diálogo entre essas correntes de pensamento possibilitou problematizar os efeitos da heteronormatividade nas pessoas intersexuais, capaz de produzir rejeição social, invisibilidade e vulnerabilidade nos modos de existência desses sujeitos.

Made available in DSpace on 2019-10-06T17:00:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-05-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) In the present study, we report the preparation of antifungal and non-cytotoxic polymer nanocomposites with potential application in biomedical materials. Dodecanethiol-protected silver nanoparticles (AgNPs-DDT) were synthesized by a reduction/precipitation method and dispersed in chloroform to obtain stable colloidal dispersions. PBAT-based nanocomposites containing 0.25, 0.5 and 2 wt% AgNPs-DDT were prepared by casting method. The incorporation of AgNPs-DDT in PBAT matrix resulted in nanocomposites which combine improved mechanical performance and antifungal properties with a non-cytotoxic characteristic. School of Chemical Engineering University of Campinas (UNICAMP) Brazilian Nanotechnology National Laboratory (LNNano) Brazilian Center for Research in Energy and Materials (CNPEM) Department of Oral Biosciences and Diagnosis Institute of Science and Technology Universidade Estadual Paulista (UNESP) Physiological Science Department Piracicaba Dental School University of Campinas (UNICAMP) Instituto de Macromoléculas Professora Eloísa Mano (IMA) Universidade Federal do Rio de Janeiro (UFRJ) Department of Oral Biosciences and Diagnosis Institute of Science and Technology Universidade Estadual Paulista (UNESP) FAPESP: 2016/08595-1 FAPESP: 2016/09588-9

Supramolecular assembly of biobased components in water is a promising strategy to construct advanced materials. Herein, electrostatic complexation was used to prepare wet-resilient foams with improved mechanical property. Small-angle X-ray scattering and cryo-transmission electron microscopy experiments showed that suspensions with oppositely charged cellulose nanofibers are a mixture of clusters and networks of entangled fibers. The balance between these structures governs the colloidal stability and the rheological behavior of CNFs in water. Foams prepared from suspensions exhibited maximum compressive modulus at the mass composition of 1:1 (ca 0.12 MPa), suggesting that meaningful attractive interactions happen at this point and act as stiffening structure in the material. Besides the electrostatic attraction, hydrogen bonds and hydrophobic contacts may also occur within the clustering, improving the water stability of cationic foams. These results may provide a basis for the development of robust all- cellulose materials prepared in water, with nontoxic chemicals.

Besides interesting properties and potential applications, cellulose nanocrystals (CNCs) present some limitations which remain a challenge in many application fields. These nanomaterials are sensitive to thermal degradation due to their natural source and surface characteristics, limiting their processing at high temperature. In this study, pristine sisal fibers were bleached using different acid (ABF) and basic (BBF) techniques prior to sulfuric acid hydrolysis under the same conditions. This procedure provided two CNCs with different characteristics (ACNC and BCNC). The compositions of the bleached cellulosic pulps were characterized and was found that ABF and BBF presented different cellulose contents of 61.5 and 72.4% respectively. It clearly impacts the thermal behavior of the obtained nanomaterials, leading BCNC to present a maximum degradation temperature of approximately 100 °C higher than ACNC. Other CNC characteristics, such as surface charge, crystallinity and aspect ratio also seem to play an important role in relation to the thermal behavior. A decrease in the stability and the modification of the volatile content and composition were observed during the thermal degradation.

Cellulose nanofibers (CNF) can present a high viscosity and thixotropic behavior when dispersed in water. In this work, CNF isolated from sugarcane bagasse and modified by N-oxyl-2,2,6,6-tetramethylpiperidine (TEMPO) oxidation was added to a solution of carboxymethyl cellulose (CMC). This process produced an unexpected viscosity due to a synergistic effect that was observed macroscopically through rheology analysis. The phenomenon known as depletion flocculation was observed, which was caused by the reduction of the excluded volume. The interactions of the system were studied by ultraviolet-visible spectroscopy (UV-Vis), optical microscopy, and cryogenic transmission electron microscopy (cryo-TEM), which demonstrated the presence of the particle/polymer repulsion and subsequent formation of domains composed of aligned micro and nanocellulose particles clusters and nanofibers distributed throughout the sample, forming a percolated 3D structure responsible for a strong gelling and colloidal stability.

International audience; Cellulose nanocrystals (CNC) and nanofibrils (CNF) were obtained by acid hydrolyzis and mechanical treatment, respectively, of cellulosic fibers from paper. Additionally, surface modification was performed for CNC by neutralization (NaOH) and oxidation (TEMPO). The thermal stability, surface properties and rheological behavior of these nanomaterials were compared. A clear difference in CNC surface was found upon neutralization and oxidation treatments, leading to distinct thermal behaviors. Optical and rheological properties were found to be predominantly by the particles size, being strongly affected by inertial effects.

Cellulose nanofibers (CNF) were isolated from Curaua fibers (Ananas erectifolius L. B. Smith) through a mechanical grinder preceded by mild chemical treatment. Morphology and surface characteristics of the fibers were followed until it reaches the nanoscale as long and flexible nanofibers. In aqueous suspensions, SAXS techniques revealed that such nanofibers present a twisted ribbon structure while rheological measurements demonstrate its high viscosity and a thixotropic behavior. These characteristics suggests the potential application of CNF in biomedical field, which, in turn, stimulates the toxicological studies of such materials. The obtained materials do not show any sign of cytotoxicity by direct or indirect assays for cell viability and cell morphology using Vero cells. Moreover, during the adhesion test, the cells demonstrated higher affinity to the CNF surface. It can be related to its surface properties and its obtaining conditions, which did not use any hazardous chemicals.

Cellulosic nanoparticles with high Young's modu- lus, crystallinity, specific surface area, and aspect ratio can be found in the natural structure of plant fibers. Indeed, lignocel- lulosic fibers consist of semicrystalline cellulose nanofibrils embedded in an amorphous matrix mainly composed of lignin and hemicelluloses. These nanostructures give the mechanical strength to higher plant cells, and are biodegradable, renew- able, resistant, and widely available to produce nanocompo- sites with low density, and improved and controlled mechanical, optical, and barrier properties. Nanoparticles can be extracted from cellulose using a top-down mechanically or chemically assisted deconstructing strategy, and owing to their highly reactive surface ensuing nanomaterials can be chemi- cally modified to tailor their properties for a wide range of applications. This review is limited to cellulose chemically extracted nanocrystals and aims to provide an overview about several aspects that involve this material, including sources, properties, challenges, and perspectives. V C 2014 Wiley Periodi- cals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 00, 000-000

Cellulose nanocrystals (CNCs) are appealing nanomaterials for the reinforcement of polymeric materials. It is now well established that high mechanical properties are obtained when preparing the nanocomposite by casting/evaporation methods and using CNC contents above the percolation threshold. This phenomenon results from the formation of a stiff CNC network within the matrix meaning that the properties of the matrix play only a limited role on the mechanical properties of the material when the matrix is in the rubbery state. In subpercolation concentration or when using a different processing technique, the level of understanding is less clear, mainly when the CNC-induced crystallization of the matrix interferes with the reinforcing mechanism. In this study, we used CNCs with different aspect ratios to prepare nanocomposites by extrusion with polybutyrate adipate terephthalate as matrix. The impact of CNC on the crystallinity of the matrix and mechanical properties of the nanocomposite has been investigated. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2284–2297

Cellulose nanocrystals (CNCs) were isolated from soy hulls by acid sulfuric hydrolysis. The resulting CNCs were characterized using TEM, AFM, WAXS, elemental analysis and TGA. The CNCs have a high crystallinity, specific surface area and aspect ratio. The aspect ratio (around 100) is the largest ever reported in the literature for a plant cellulose source. These CNCs were used as a reinforcing phase to prepare nanocomposite films by casting/evaporation using natural rubber as matrix. The mechanical properties were studied in both the linear and non-linear ranges. The reinforcing effect was higher than the one observed for CNCs extracted from other sources. It may be assigned not only to the high aspect ratio of these CNCs but also to the stiffness of the percolating nanoparticle network formed within the polymer matrix. Moreover, the sedimentation of CNCs during the evaporation step was found to play a crucial role on the mechanical properties.

Composite materials were prepared by extrusion and injection molding from polybutyrate adipate terephthalate (PBAT) and high aspect ratio cellulose nanocrystals (CNCs) extracted from capim dourado fibers. Three CNC contents were used, corresponding to 0.5, 1, and 2 times the theoretical percolation threshold. Small-amplitude oscillary shear (SAOS) experiments show that as the CNC content increases, a more elastic behavior is observed but no percolating network can form within the polymeric matrix as a result of the high shear rates involved during the injection-molding process. Annealing of the samples at 170 °C was performed, and the possible reorganization of the nanofiller was investigated. This reorganization was further elucidated using 2D-SAOS and creep experiments.

A dissertação tem como objetivo estudar como se desdobram as experiências trans nos modos de vida de suas famílias a partir das narrativas de vida das colaboradoras de pesquisa em Natal-RN. Para isso, metodologicamente o trabalho constitui-se como uma pesquisa qualitativa ancorada pela realização de entrevistas com questionários semiestruturados com três famílias. Será usado também, como método analítico das narrativas de vida das colaboradoras de pesquisa, a análise do discurso (FOUCAULT, 1996). Almejamos articular as noções de moral em sociologia com os casos relatados no processo de pesquisa, com o intuito de problematizar a transfobia familiar e desvelar as mudanças geracionais das relações familiares das travestis e transexuais relacionando os estudos da pesquisa com as etnografias produzidas sobre o tema no Brasil. A partir da análise das narrativas de vida pôde-se alcançar temas e conceitos que foram problematizados nesta pesquisa, como por exemplo: a imposição do gênero na infância; a moral no ambiente familiar; o uso dos termos cis e trans; o desejo pela manipulação das identidades; a adoção pelo saber médico e por algumas colaboradoras de pesquisa da categoria classificatória disforia de gênero para diagnosticar as experiências trans, a existência de casos de evitação nas relações familiares e a moral nos relacionamentos amorosos das pessoas trans. Pretendemos, com isso, oferecer um trabalho que forneça conteúdo técnico, teórico e metodológico para os campos da sociologia e teoria queer. A dissertação tem como objetivo estudar como se desdobram as experiências trans nos modos de vida de suas famílias a partir das narrativas de vida das colaboradoras de pesquisa em Natal-RN. Para isso, metodologicamente o trabalho constitui-se como uma pesquisa qualitativa ancorada pela realização de entrevistas com questionários semiestruturados com três famílias. Será usado também, como método analítico das narrativas de vida das colaboradoras de pesquisa, a análise do discurso (FOUCAULT, 1996). Almejamos articular as noções de moral em sociologia com os casos relatados no processo de pesquisa, com o intuito de problematizar a transfobia familiar e desvelar as mudanças geracionais das relações familiares das travestis e transexuais relacionando os estudos da pesquisa com as etnografias produzidas sobre o tema no Brasil. A partir da análise das narrativas de vida pôde-se alcançar temas e conceitos que foram problematizados nesta pesquisa, como por exemplo: a imposição do gênero na infância; a moral no ambiente familiar; o uso dos termos cis e trans; o desejo pela manipulação das identidades; a adoção pelo saber médico e por algumas colaboradoras de pesquisa da categoria classificatória disforia de gênero para diagnosticar as experiências trans, a existência de casos de evitação nas relações familiares e a moral nos relacionamentos amorosos das pessoas trans. Pretendemos, com isso, oferecer um trabalho que forneça conteúdo técnico, teórico e metodológico para os campos da sociologia e teoria queer.

Natural rubber (NR) latex particles were oxidized using KMnO4 as oxidant to promote the insertion of hydroxyl groups in the surface polyisoprene chains. Different degrees of oxidation were investigated. Both unoxidized and oxidized NR (ONR) latex were used to prepare nanocomposite films reinforced with cellulose nanocrystals (CNCs) by casting/evaporation. The oxidation of NR was carried out to promote chemical interactions between the hydroxyl groups of ONR with those of CNCs through hydrogen bonding. The effect of the degree of oxidation of the NR latex on the rheological behavior of CNC/NR and CNC/ONR suspensions, as well as on the mechanical, swelling and thermal properties of ensuing nanocomposites was investigated. Improved properties were observed for intermediate degrees of oxidation but they were found to degrade for higher oxidation levels.

Cellulose nanocrystals (CNCs) were produced from eucalyptus wood pulp using three different methods: (i) classical sulphuric acid hydrolysis (CN-I), (ii) acid hydrolysis of cellulose previously mercerized by alkaline treatment (MCN-II), and (iii) solubilization of cellulose in sulphuric acid and subsequent recrystallization in water (RCN-II). The three types of CNCs exhibited different morphologies and crystalline structures that were characterized using complementary imaging, diffraction and spectroscopic techniques. CN-I corresponded to the type I allomorph of cellulose while MCN-II and RCN-II corresponded to cellulose II. CN-I and MCN-II CNCs were acicular particles composed of a few laterally-bound elementary crystallites. In both cases, the cellulose chains were oriented parallel to the long axis of the particle, although they were parallel in CN-I and antiparallel in MCN-II. RCN-II particles exhibited a slightly tortuous ribbon-like shape and it was shown that the chains lay perpendicular to the particle long axis and parallel to their basal plane. The unique molecular and crystal structure of the RCN-II particles implies that a higher number of reducing chain ends are located at the surface of the particles, which may be important for subsequent chemical modification. While other authors have described nanoparticles prepared by regeneration of short-chain cellulose solutions, no detailed description was proposed in terms of particle morphology, crystal structure and chain orientation. We provide such a description in the present paper.

This paper presents a low cost solution for Digital Operating Rooms called MIR (Multimedia Integrated Room). MIR is capable of real time transmission and recording of endoscopic procedures using multiple HD cameras, integration with the hospital systems and also can be easily controlled by a wireless mobile device. The developed system main application areas are: a) medical students and specialist preceptor to follow the surgical procedure remotely; b) the surgical team to better visualize the surgery.

Strawberry is a non-climacteric fruit with a very short postharvest shelf-life. Loss of quality in this fruit is mostly due to its relatively high metabolic activity and sensitivity to fungal decay, meanly grey mold (Botrytis cinerea). In this study, the ability of gelatin coatings containing cellulose nanocrystals (CNC) to extend the shelf-life of strawberry fruit (Fragaria ananassa) over 8 days were studied. The filmogenic solution was obtained by the hydration of 5 g of gelatin (GEL) in 100 mL of distillated water containing different amounts of CNC dispersion (10 mg CNC/g of GEL or 50 mg of CNC/g of GEL) for 1 hour at room temperature. After this period, the solution was heated to 70 °C and maintained at this temperature for 10 minutes. The plasticizer (glycerol) (10g/100g of the GEL) was then added with constant, gentle stirring in order to avoid forming air bubbles and also to avoid gelatin denaturation until complete homogenization. Strawberries (purchased at the local market) were immersed in the filmogenic solution for 1 minute and after coated were dried at 15 °C by 24 hours. The strawberries were then kept under refrigeration and characterized in terms of their properties (weight loss, ascorbic acid content, titratable acidity, water content). The results have shown that samples covered with GEL/CNC had a significant improvement in its shelf- life. For instance, for the control sample (without coating) the weight loss after 8 days of storage was around 65%, while covered samples loss in the range of 31-36%. Edible coating was also effective in the retention of ascorbic acid (AA) in the strawberries, while control sample presented a fast decay in the AA content, covered samples showed a slow decay in the AA concentration. Moreover, the use of GEL/CNC edible coating had an antimicrobial effect in the fruits.