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Diante do cenário atual desfavorável do ensino de Física na Educação Básica brasileira, novas estratégicas metodológicas são sugeridas para propor uma aprendizagem significativa. O uso de simuladores virtuais educacionais, em especial os disponíveis no Physics Educacional Technology (PhET), se inserem nesse contexto como potencial alternativa para tratar essa questão. Este trabalho tem como objetivos compreender a prática desses simuladores no processo de ensino-aprendizagem (em especial de Física), relacionando-a com teóricos como Ausubel, Freire e Vigotsky, e analisar os temas do currículo abordados nas simulações do PhET para o Ensino Fundamental. Para isso, foi realizada uma revisão bibliográfica exploratória-descritiva a partir de dados da literatura disponíveis no Portal de Periódicos Capes, Google Acadêmico, Scopus e no PhET. Os dados foram interpretados qualitativamente ou representados na forma de tabelas e de agrupamento de palavras-chave. Os resultados mostraram que há uma grande variedade de simuladores disponíveis para o Ensino Fundamental, distribuídos por temas que são trabalhados no currículo. Além disso, verificou-se que a proposta do uso do PhET no ensino de Física está de acordo com o que defendem os teóricos destacados, considerando a evolução conceitual e a aprendizagem significativa da criança frente às constantes transformações socioculturais.

In this work, Zn2+-doped TiO2:WO3 nanostructured films, with different doping levels, were produced by electrospinning followed by sintering, and tested as potential materials for relative humidity (RH) detection. The materials microstructure was investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray diffraction (XRD). The electrical characterization was performed by electrical impedance spectroscopy in the range of 400 HZ–40 MHZ, at 20 °C. The sensors’ sensitivity to moisture was evaluated from the impedance variations in response to changes in RH (10–100%). The analyses confirmed the interaction of water molecules with the oxides surface, and showed that zinc atoms were incorporated into the titanium vacancies in the crystal lattice. All the studied sensors showed a p- to n-type conduction transition taking place at around 40% RH. The nanocomposite with 2 wt% of dopant presented the best sensitivity to moisture, with an impedance variation of about 1 order of magnitude. The results are discussed in relation to the microstructure and fabrication route.

The increased demands and dependence on depleted oil reserves, accompanied by global warming and climate change have driven the world to explore and develop new strategies for global sustainable development. Among sustainable biomass sources, microalgae represent a promising alternative to fossil fuel and can contribute to the achievement of important Sustainable Development Goals (SDGs). This article has reviewed the various applications of microalgal biomass that includes (i) the use in aquaculture and its sustainability; (ii) commercial value and emerging extraction strategies of carotenoids; (iii) biofuels from microalgae and their application in internal combustion engines; (iv) the use and reuse of water in microalgae cultivation; and (v) microalgae biotechnology as a key factor to assist SDGs. The future prospects and challenges on the microalgae circular bio economy, issues with regard to the scale-up and water demand in microalgae cultivation are also highlighted.

In this work,&nbsp, Nb5+&nbsp, and In3+&nbsp, ions were used as dopants in titanium/tungsten oxide nanostructures that are produced by the electrospinning and sintering process, for relative humidity (RH) detection. The microstructural properties were investigated by SEM, EDS, XRD, Raman and FTIR techniques. The electrical response characterization of the samples was performed by electrical impedance spectroscopy in the range of 400 Hz to 40 MHz, at 20 °C. The sensors sensitivity to moisture was evaluated in terms of the impedance variations to RH (10–100%). The combined analysis of the microstructural characterization results confirmed the surface interaction between the oxides and the ions incorporation in Ti crystal lattice. All the studied sensors showed a conduction transition from p- to n-type at around 30–40% RH: besides, they also displayed better sensitivity to moisture than those obtained in a previous work using titanium/tungsten combination using a different fabricationn route. The impedance modulus variation up to 1.1 and 1.3 orders of magnitude for the 4 wt % niobium and indium doped samples, respectively. The results are directly associated with the microstructure and alternative preparation process.

In this work, Nb5+ and In3+ ions were used as dopants in titanium/tungsten oxide nanostructures that are produced by the electrospinning and sintering process, for relative humidity (RH) detection. The microstructural properties were investigated by SEM, EDS, XRD, Raman and FTIR techniques. The electrical response characterization of the samples was performed by electrical impedance spectroscopy in the range of 400 Hz to 40 MHz, at 20 °C. The sensors sensitivity to moisture was evaluated in terms of the impedance variations to RH (10–100%). The combined analysis of the microstructural characterization results confirmed the surface interaction between the oxides and the ions incorporation in Ti crystal lattice. All the studied sensors showed a conduction transition from p- to n-type at around 30–40% RH: besides, they also displayed better sensitivity to moisture than those obtained in a previous work using titanium/tungsten combination using a different fabricationn route. The impedance modulus variation up to 1.1 and 1.3 orders of magnitude for the 4 wt % niobium and indium doped samples, respectively. The results are directly associated with the microstructure and alternative preparation process.

Equações Literais são expressões matemáticas que possuem, além da variável em questão, coeficientes representados de forma genérica por letras. Essas equações recebem destaque na busca por uma aprendizagem de matemática mais significativa, uma vez que podem ser utilizadas para modelar e interpretar inúmeros fenômenos em diversas áreas do conhecimento. Neste trabalho, avaliou-se a proficiência de professores de matemática em equações literais a partir das respostas dadas por eles a questionários que discutiam aspectos da formação acadêmica, da prática docente e do conhecimento técnico sobre o assunto. Os dados coletados foram analisados via modelo de Rasch Dicotômico, antes e depois da disponibilização de um manual didático aos participantes da pesquisa, produzido para sanar possíveis dificuldades com o tema. Os resultados iniciais se mostraram bastante preocupantes uma vez que, para a grande maioria dos participantes, o modelo retornou que a habilidade desses profissionais era insuficiente para que respondessem positivamente aos itens sobre o conhecimento do conteúdo. Esse resultado foi relacionado com a formação inicial e o exercício docente. Por outro lado, verificou-se que após a capacitação com o manual didático, o nível de conhecimento desses indivíduos aumentou significativamente nos quesitos avaliados inicialmente, com consequente aumento das probabilidades de sucesso com o tema.

Humidity is a critical environmental parameter for several production processes and its control/monitoring is of great importance in maintaining the quality of goods and products. In this context, metallic oxide ceramic nanostructures are materials of great technological interest in the fabrication of moisture sensors because they have good chemical/structural stability and high surface area/volume ratio. The electrical response of these sensors relates to the chemisorbed and physisorbed layers of water molecules on the surface of the ceramic particles and to the capillary condensation of water in the microscopic pores between the particles. Based on these aspects, this work presents the fundamentals, electrical/electronic properties, influence of dopants, novel preparation procedure by electrospinning and perspectives of application of TiO2:WO3 metal oxide heteronanostructures as humidity sensors.

Metal oxide composites have attracted much consideration due to their promising applications in humidity sensors in response to the physical and chemical property modifications of the resulting materials. This work focused on the preparation, microstructural characterization and analysis of humidity-dependent electrical properties of undoped and vanadium oxide (V2O5)-doped titanium oxide/tungsten oxide (TiO2/WO3) sintered ceramic films obtained by electrospinning. The electrical properties were investigated by impedance spectroscopy (400 Hz–40 MHz) as a function of relative humidity (RH). The results revealed a typical transition in the transport mechanisms controlled by the appropriated doping level of V2O5, which introduces important advantages to RH detection due to the atomic substitution of titanium by vanadium atoms in highly doped structures. These aspects are directly related to the microstructure modification and structure fabrication procedure.

The performance of metal oxide-based devices for humidity impedimetric sensors depends on different conduction mechanisms during water molecules adsorption. As consequence, new strategies for development of hierarchical and doped structures of mixed metal oxides play a critical role in the production of more efficient humidity sensors. It is reported an alternative method for synthesis of hexagonal ZnO nanocrystals on TiO2-decorated electrospun fibers, allowing the production of ordered arrays of hierarchical TiO2/ZnO nanostructures. Polymeric matrix supporting fibers were removed after annealing (500 °C), providing nanostructures with promising application as low-cost humidity sensors. The structure of resulting materials was explored in addition to the influence of relative humidity (RH) (measured in the range 400 Hz–40 MHz) on complex impedance spectra.

Background: Usnic acid has been progressively reported in the literature as one of the most important lichen metabolites characterized by a rich diversity of applications such as antifungal, antimicrobial, antiprotozoal and antiviral agent. Particularly, antimicrobial activity of usnic acid can be improved by encapsulation of active molecules in enteric electrospun fibers, allowing the controlled release of active molecule at specific pH. Few relevant patents to the topic have been reviewed and cited. Methods: Bactericidal activity of usnic acid-loaded electrospun fibers of Eudragit L-100 and polyvinylpyrrolidone was examined against Staphylococcus aureus using inhibition hales methodology. Results: The controlled release of active material at high pH is established after 10 minutes of interaction with media and results in reasonable activity against S. aureus, as detected by inhibition hales. Conclusion: The strong biological activity of usnic acid-loaded electrospun fibers provides a promising application for corresponding material as a bactericidal agent for wound healing treatment.

TiO2/ZnO hierarchical heteronanostructures were produced following a two-step procedure in which the hydrothermal growth of nanorods takes place on the surface of decorated electrospun fibers. The reaction product was a 3D-nanorod arrangement of a single-phase hexagonal wurtzite deposited onto the surface of a TiO2-decorated 1D-polymer nanoporous structure. The resulting composite was characterized as a potential candidate for photocatalytic applications, due to the available surface area and the high concentration of charge carriers, which minimizes the recombination of electrons and holes during photocatalytic processes. Photodegradation tests using rhodamine B (under visible-light irradiation) were performed to explore the photocatalytic activity of the nanostructures. Dye photodegradation ratio was determined to be 90% after 70 min, which indicates that TiO2/ZnO hierarchical heteronanostructures are potential photocatalysts.

The production of electrospun fibers of enteric polymer for controlled delivery of drugs represents a simple and low cost procedure with promising advantages relative to the longer therapeutic window provided by cylindrical geometry in association with intrinsic properties of pH-dependent drug carriers. In this work, we have explored the incorporation of additives (block copolymers of poly(ethylene)-b-poly(ethylene oxide)) into matrix of Eudragit L-100 and the effective action of hybrid composites on delivery of nifedipine, providing improvement in the overall process of controlled release of loaded drug.

Hybrid ZnO/TiO2nanoparticles were applied as potential photocatalyst agents incorporated into electrospun fibers of enteric block copolymers. The resistance of fibers avoids aggregation and contributes to prolonged action of semiconductor nanoparticles under continuous light irradiation. Such behavior is attributed to the minimal aggregation degree and elevated efficiency of photodegradation of modified nanoparticles in comparison with pristine ones. Hybrid ZnO/TiO2in nanofibers contributes to the association of different mechanisms such as N-deethylation and cleavage of dye molecules applied in the overall process of photodegradation.

The study of selective metal oxide-based binary/ternary systems has received increasing interest in recent years due to the possibility of producing efficient new ceramic materials for relative humidity (RH) detection, given the superior properties of the mixed compounds in comparison with pristine ones. The aim of this work was focused on preparation and characterization of non-doped and Nb2O5-doped TiO2 : WO3 pair (in the pellet form) and evaluation of corresponding humidity-dependent electrical properties. The microstructure of the samples was analyzed from scanning electron microscopy, X-ray diffraction patterns, Raman spectra, BET surface area analysis, and porosimetry. The electrical characterization was obtained from impedance spectroscopy (100 Hz to 40 MHz) in the 10–100% RH range. The results showed that adequate doping levels of Nb2O5 introduce important advantages due to the atomic substitution of Ti by Nb atoms in highly doped structures with different levels of porosity and grain sizes. These aspects introduced a key role in the excursion (one order of magnitude) in the bulk resistance and grain boundary resistance, which characterizes these composite ceramics as a promising platform for RH identification.

Submitted by Marcio Luis Ferreira Nascimento (mlfn@ufba.br) on 2015-06-26T00:41:21Z No. of bitstreams: 1 LiteratureElectrospinningNanofibersHistoricalTrendsFuture-RPN9-Nascimento.PDF: 2582584 bytes, checksum: 822397ac551d11f8444a6e86dc65a5b7 (MD5) Approved for entry into archive by Rodrigo Meirelles (rodrigomei@ufba.br) on 2015-07-20T21:53:10Z (GMT) No. of bitstreams: 1 LiteratureElectrospinningNanofibersHistoricalTrendsFuture-RPN9-Nascimento.PDF: 2582584 bytes, checksum: 822397ac551d11f8444a6e86dc65a5b7 (MD5) Made available in DSpace on 2015-07-20T21:53:10Z (GMT). No. of bitstreams: 1 LiteratureElectrospinningNanofibersHistoricalTrendsFuture-RPN9-Nascimento.PDF: 2582584 bytes, checksum: 822397ac551d11f8444a6e86dc65a5b7 (MD5) Previous issue date: 2015 The development of new fibrilar materials based on electrospinning (ES) technique has a notable history of nearly four centuries of discoveries and results. The eletrospinning manufacturing is one of the most widely reported methods for nanofiber (NF) manufacturing, providing security, high quality and productivity. In spite of the first patent about electrospinning has been applied in April 5th, 1900 by John Francis Cooley, a historical perspective (since 1600s) about this amazing discovery represents an important step for future applications. Nanofibers have been considered one of the top interesting fundamental study objects for academicians, and greatest intriguing business materials for modern industry. As a consequence, lucrative organizations and companies have explored the relevance of nanofibers. In this paper, the quantity of published manuscripts and patent inventions is presented and the correlation of research activities to the production of new electrospinning materials is shown. China and the United States have been leading in electrospinning and nanofibers development. The company triumph is mostly dependent on applications improvement relevant for broader business society. A dramatic rise of interest in nanofibers produced by electrospinning technique has been confirmed due to the publication data, author’s affiliation, keywords, and essential characterization procedures. Is has been shown that the number of publications on electrospinning and nanofibers researches from academic institutions is higher than industrial laboratories. More than 1,891 patents using the term “electrospinning” and 2,960 with the term “nanofibers” according to the European Patent Office at title or abstract have been filed around the world up to 2013. These numbers just continue to increase along with worldwide ES-related sales. Curiously, for the same period 11,973 electrospinning documents and 18,679 nanofibers-related (mainly manuscripts) were published considering the Scopus database with the same terms in the title, abstract or using keywords. Thus, statistically, there are more published manuscripts worldwide than patents for both keywords

We report the electrical behavior of emulsions (water/toluene/triton X-100) characterized by double phase inversion induced by temperature. The phase inversions in the continuous media were easily detected from the measurement of slope in the real part of impedance at low frequencies (1Hz

In this paper, we analyze the use of electrical impedance spectroscopy (EIS) to investigate the aggregational processes of low molecular weight polyethylene-b-polyethylene oxide copolymer (PE-b-PEO (50% PEO)) induced by concentration. The real and imaginary part of impedance have been compared to theoretical results based on equivalent circuits, providing information pertaining to the properties of the bulk and contributions due to the interactions at the electrolyte/electrode interface. The bulk resistance is used as a convenient tool for identifying structures such as spheres (S), hexagonally packed cylinders (HPC) and lamellar phases. To characterize the transition mechanisms involved in micellization we applied the Phillips criteria, associating the maximum change in the gradient of bulk resistance with the formation of micelles. The transition from micelles to HPC structures is characterized from the minimum in the bulk resistance, while the electrical signature relative to the formation of lamellar structures is characterized by the decrease in the diffusion (reduction in the polarization effects) and the inversion in the slope of bulk resistance as a function of copolymer concentration. Thus, the EIS may be defined as a convenient tool for characterizing the conformation and phase transitions in amphiphilic block copolymers.