Diversidade, Tensões e Limites nas manifestações de 2013

This article seeks to explain the relationship between the events that marked the demonstrations of June 2013 and the inclusion in the policy of the National Congress agenda restrictive bills on the use of internet and other spaces for political purposes. Reports on demonstrations, legal aspects and analysis of other researchers were used. The theoretical context of this analysis is composed by reflections and concepts of Hebert Marcuse and Alain Touraine on protest movements and social domination.Este artigo procura explicar as relações entre os eventos que marcaram as Manifestações de Junho de 2013 e a inserção na agenda política do Congresso Nacional de projetos de lei restritivos quanto ao uso da internet e outros espaços para finalidades políticas. Reportagens sobre as Manifestações, aspectos legais e análise de outros pesquisadores foram utilizadas. O contexto teórico desta análise se compôs pelas reflexões e conceitos de Hebert Marcuse e Alain Touraine sobre movimentos contestatórios e dominação social

Amyloid peptide mixtures: self-assembly, hydrogelation, nematic ordering and catalysts in aldol reactions

Morphological, spectroscopic and scattering studies of the self-assembly and aggregation process of mixtures of [RF]4 and P[RF]4 peptides (where: R = arginine; F = phenylalanine; P = proline), in solution and as hydrogels, were performed to obtain information about polymorphism. CD data confirmed a β-sheet secondary structure conformation for the solutions and TEM images revealed nanofibers with diameters of ~ 10 nm and micrometer lengths. SAXS curves were fitted using a mass fractal-component and a long cylinder shell form factor for the liquid samples, and only a long cylinder shell form factor for the gels. Increasing the P[RF]4 content in the systems leads to a reduction in cylinder radius and core density scattering, suggesting an increase in packing of the peptide molecules; however, the opposite effect was observed for the gels. Remarkably, the gels are birefringent, indicating nematic ordering of the gel fibrils. These compounds show potential as catalysts in the asymmetric aldol reactions, with cyclohexanone and p-nitrobenzaldehyde in aqueous media. A moderate conversion (36.9 %) and a good stereoselectivity (69:31) were observed for the system containing only [RF]4, and with the increase of the P[RF]4, a considerable decrease of the conversion was observed, suggesting differences in the self-assembly and packing factor. Rheological measurements were performed to determine the shear moduli for the soft gels. These model amyloid peptides demonstrate a range of tunable self-assembly behaviors and additionally have potential as biocatalysts

AREIAS EM MOVIMENTO - UM ESTUDO SOBRE A MORFODINÂMICA DA ILHA COMPRIDA - SP

For every environmental planning or management, understand the natural dynamic that governs the physical attribute of the space is an exigency. This understanding assumes larger importance in coastal areas face the speed of the action of agents that there act. The Ilha Comprida, south coast of São Paulo State (Brazil), with 74 Km of coastline, was defined as study area. That barrier island was formed by glacio-iso-eustatic events. For the study of the geomorphologic evolution of this Island, maps were made in three different scenarios - 1962, 1974 and 1991, being used for these stereoscope equals of aerial photographs in the scale 1:25,000. Thus, starting from the comparison and overlap of the same ones, it can be proven the great morphologic variation presented by the Ilha Comprida. The main verification is increment of area in its northeast extremity, caused by the contribution of sands. The erosive processes are linked to the progress of the coastline in detriment of the shore terrace, but at few points. In the interior margin of the Ilha Comprida the constant joining of “islands” and sandy banks have been the main geomorphologic modification found. The causes of this process, are the great mass of sediments and low energy of the river channels. Key-words: morphodynamic, coastal geomorphology, Ilha Comprida (SP - Brazil) INTR0 entendimento da dinâmica que rege os atributos físicos do meio ambiente é imprescindível em todo trabalho de planejamento e gestão ambiental. Este entendimento assume maior significância em se tratando de áreas costeiras face a rapidez da ação dos agentes que ali atuam. A Ilha Comprida, localizada no litoral sul do Estado de São Paulo, no “Complexo Estuarino-Lagunar de Iguape/Cananéia”, foi definida como área de estudo. A Ilha, geomorfologicamente uma ilha barreira, apresenta uma linha de costa com 74 Km de comprimento, sua face interna, separada do continente por um canal de maré apresenta um comprimento de 80 Km. Sua gênese está vinculada a uma conjunção de eventos de natureza glácio-iso-eustáticos. Para o estudo da evolução geomorfológica desta Ilha, foram efetuados mapeamentos relativos a três cenários distintos - 1962, 1974 e 1991, utilizando-se para isto de pares estereoscópios de fotografias aéreas na escala 1:25.000. Assim, a partir da comparação e sobreposição dos mesmos, pode-se comprovar a grande variação morfológica apresentada pela Ilha, associada aos processos erosivos e deposicionais. A principal constatação é o acréscimo, em área, na sua extremidade nordeste, ocasionada pelo aporte de areias. Os processos erosivos estão vinculados a progradação do estirâncio em detrimento do recuo do terraço marinho, mas tais processos são pontuais ao longo da linha de costa. Na margem interior da Ilha, devido ao enorme volume de sedimentos aportados e a fraca energia do fluxo d’ água, tem-se observado um constante acoplamento de “ilhas” e/ou bancos arenosos a sua área. Palavras-chave: morfodinâmica, geomorfologia litorânea, Ilha Comprida (SP - Brasil

Self-assembly, nematic phase formation and organocatalytic behaviour of a proline-functionalized lipopeptide

The self-assembly of the amphiphilic lipopeptide PAEPKI-C16 (P = proline, A = alanine, E = glutamic acid, K = lysine, I = isoleucine, C16 = hexadecyl) was investigated using a combination of spectroscopic, microscopic and scattering methods and compared to C16-IKPEAP with the same (reversed) peptide sequence and the alkyl chain positioned N-terminally and which lacks a free N-terminal proline residue. The catalytic activity of these peptides were then compared using a model aldol reaction system. For PAEPKI-C16, Cryo-TEM images showed the formation of micrometer length fibers, which by Small-angle X-ray scattering (SAXS) were found to have a radius of 2.5 - 2.6 nm. Spectroscopic analysis shows these fibers are built from -sheets. This behaviour is in complete contrast to that of C16-IKPEAP which forms spherical micelles with peptides in a disordered conformation [Hutchinson, J. A. et al. J. Phys. Chem. B 2019, 123, 613]. For PAEPKI-C16, the spontaneous alignment of fibers was observed upon increasing pH, which was accompanied by observed birefringence and anisotropy of SAXS patterns. This shows the formation of a nematic liquids and unprecedented nematic hydrogel formation was also observed these lipopeptides at sufficiently high concentrations. SAXS shows retention of an ultrafine (1.7 nm core radius) fibrillar network within the hydrogel. PAEPKI-C16 with free N-terminal proline shows enhanced anti:syn diastereoselectivity and better conversion compared to C16-IKPEAP. The cytotoxicity of PAEPKI-C16 was also lower than C16-IKPEAP for both fibroblast and cancer cell lines. These results highlight the sensitivity of lipopeptide properties to the presence of a free proline residue. The spontaneous nematic phase formation by PAEPKI-C16 points to the highly anisotropy of its ultrafine fibrillar structure and the formation of such a phase at low concentration in aqueous solution may be valuable for future applications

β ‐ sheet assembly in amyloidogenic glutamic acid nanostructures: insights from X‐ray scattering and infrared nanospectroscopy

Glutamic acid–rich peptides are crucial to a variety of biological processes, including glutamatergic neurotransmission and immunological defense. Glutamic acid sequences often exhibit unusual organization into β2‐type sheets, where bifurcated H bonds formed between glutamic acid side chains and NH in amide bonds on adjacent β‐strands play a paramount role for stabilizing the molecular assembly. Herein, we investigate the self‐assembly and supramolecular structure of simplified models consisting of alternating glutamic acid/phenylalanine residues. Small‐angle X‐ray scattering and atomic force microscopy show that the aggregation pathway is characterized by the formation of small oligomers, followed by coalescence into nanofibrils and nanotapes. Amyloidogenic features are further demonstrated through fiber X‐ray diffraction, which reveal molecular packing according to cross‐β patterns, where β‐strands appear perpendicularly oriented to the long axis of nanofibrils and nanotapes. Nanoscale infrared spectroscopy from individual nanoparticles on dried samples shows a remarkable decrease of β2‐sheet content, accompanied by growth of standard β‐sheet fractions, indicating a β2‐to‐β1 transition as a consequence of the release of solvent from the interstices of peptide assemblies. Our findings highlight the key role played by water molecules in mediating H‐bond formation in β2‐sheets commonly found in amyloidogenic glutamic acid–rich aggregates

Concepciones de estudiantes de secundaria sobre soluciones químicas: reflexiones a partir del desarrollo de una secuencia didáctica

The present study was developed as part of the activities of the Stage IV curricular component, at a State College in the city of Itapetinga-BA. Based on the adaptation of the works of Alves and Ribeiro (2019) and Silva and Vasconcelos (2020), we seek to understand which high school students' conceptions about the content of Solutions can be developed through the application of a didactic sequence (SD) in Chemistry classes. Furthermore, identify challenges in learning the content, as well as the presence of macroscopic and microscopic aspects during classes. For this, qualitative research was conducted, using two questionnaires as a data collection instrument, one at the beginning and another at the end of SD. SD was composed of seven pedagogical actions with two hours of classes at each time, with a workload equivalent to 14 hours. At the end of the SD, it was possible to identify the progress of the students' learning, as in many of the answers presented, they managed to overcome the errors in their conceptions. Furthermore, few students discussed microscopic aspects in class and the challenges in understanding the subject were minimized.O presente estudo foi desenvolvido como parte das atividades do componente curricular de Estágio IV, em um Colégio Estadual da cidade de Itapetinga-BA. A partir da adaptação dos trabalhos de Alves e Ribeiro (2019) e Silva e Vasconcelos (2020), buscamos compreender quais concepções de estudantes do Ensino Médio sobre o conteúdo de Soluções podem ser elaboradas a partir da aplicação de uma sequência didática (SD) em aulas de Química. Além disso, identificar os desafios na aprendizagem do conteúdo, como também a presença dos aspectos macroscópicos e microscópicos durante as aulas. Para isso, uma pesquisa qualitativa foi conduzida, utilizando como instrumento de coleta de dados dois questionários, um no início e outro ao final da SD. A SD foi composta por sete ações pedagógicas com duas h/aulas de cada momento, sendo a carga horária da mesma equivalente a 14h. Ao término da SD foi possível identificar o avanço da aprendizagem dos alunos, pois em muitas das respostas apresentadas eles conseguiram superar os erros em suas concepções. Outrossim, poucos alunos discutiram em sala aspectos microscópicos e os desafios foram minimizados na compreensão do assunto.El presente estudio fue desarrollado como parte de las actividades del componente curricular de la Pasantiá Supervisionada IV, en un Colegio Estadual de la ciudad de Itapetinga-BA. A partir de la adaptación de los trabajos de Alves y Ribeiro (2019) y Silva y Vasconcelos (2020), buscamos comprender qué concepciones de los estudiantes de secundaria sobre el contenido de Soluciones pueden desarrollarse mediante la aplicación de una secuencia didáctica (SD) en las clases de Química. Además, identificar desafíos en el aprendizaje de los contenidos, así como la presencia de aspectos macroscópicos y microscópicos durante las clases. Para ello se realizó una investigación cualitativa, utilizando como instrumento de recolección de datos dos cuestionarios, uno al inicio y otro al final de SD. SD estuvo compuesto por siete acciones pedagógicas con dos horas de clases cada vez, con una carga horaria equivalente a 14 horas. Al finalizar el SD se pudo identificar el avance del aprendizaje de los estudiantes, pues en muchas de las respuestas presentadas lograron superar los errores en sus concepciones. Además, pocos estudiantes discutieron aspectos microscópicos en clase y se minimizaron los desafíos para comprender el tema

Spectroscopic characterization and investigation of the dynamic of charge compensation process of supramolecular films derived from tetra-2-pyridyl-1,4-pyrazine ligand

This work describes the infrared spectroscopy characterization and the charge compensation dynamics in supramolecular film FeTPPZFeCN derived from tetra-2-pyridyl-1,4-pyrazine (TPPZ) with hexacyanoferrate, as well as the hybrid film formed by FeTPPZFeCN and polypyrrole (PPy). For supramolecular film, it was found that anion flux is greater in a K+ containing solution than in Li+ solution, which seems to be due to the larger crystalline ionic radius of K+. The electroneutralization process is discussed in terms of electrostatic interactions between cations and metallic centers in the hosting matrix. The nature of the charge compensation process differs from others modified electrodes based on Prussian blue films, where only cations such as K+ participate in the electroneutralization process. In the case of FeTPPZFeCN/PPy hybrid film, the magnitude of the anions’s flux is also dependent on the identity of the anion of the supporting electrolyte.Este trabalho descreve a caracterização espectroscópica por infravermelho e o estudo da dinâmica de compensação de cargas do filme supramolecular FeTPPZFeCN derivado do ligante tetra-2-piridil-1,4-pirazina (TPPZ) com hexacianoferrato, bem como o filme híbrido envolvendo FeTPPZFeCN e uma matriz de polipirrol (PPy). Para o filme supramolecular, foi observado um aumento no fluxo de ânion em solução contendo K+ em relação ao Li+, que parece estar relacionado ao tamanho do raio iônico cristalino do K+. O processo de eletroneutralização é discutido em termos de interação eletrostática entre cátions e centros metálicos na matriz hospedeira. A natureza do processo de compensação de carga difere de outros eletrodos modificados derivados do azul da Prússia, onde somente cátions tais como K+ participam no processo de eletroneutralização. No caso do filme híbrido FeTPPZFeCN/PPy, a magnitude do fluxo de ânions é também dependente da identidade do ânion em diferentes eletrólitos de suporte.FAPESPConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)SP