Synthesis of Cr and La-codoped SrTiO3 nanoparticles for enhanced photocatalytic performance under sunlight irradiation

In this study, we report a facile polymeric citrate strategy for the synthesis of Cr,La-codoped SrTiO3 nanoparticles. The synthesized samples were well characterized by various analytical techniques. The UV-vis DRS studies reveal that the absorption edge shifts towards the visible light region after doping with Cr, which is highly beneficial for absorbing the visible light in the solar spectrum. More attractively, codoping with La exhibits greatly enhanced photocatalytic activity for the degradation of Rhodamine B under sunlight irradiation. The optimum photocatalytic activity at 1 atom% of Cr,La-codoped SrTiO3 nanoparticles is almost 6 times higher than that of pure SrTiO3 nanoparticles and 3 times higher than that of Cr-doped SrTiO3 nanoparticles. The high photocatalytic performance in the present photocatalytic system is due to codoping with La, which acts as a most effective donor for stabilizing Cr3+ in Cr,La-codoped SrTiO3 nanoparticles. More importantly, the synthesized photocatalysts possess high reusability. A proposed mechanism for the enhanced photocatalytic activity of Cr,La-codoped SrTiO3 nanoparticles was also investigated by trapping experiments. Therefore, our results not only demonstrate the highly efficient visible light photocatalytic activity of the Cr,La-codoped SrTiO3 photocatalyst, but also enlighten the codoping strategy in the design and development of advanced photocatalytic materials for energy and environmental applications.

Thermalized polarization dynamics of a discrete optical-waveguide system with four-wave mixing

Statistical mechanics of two coupled vector fields is studied in the tight-binding model that describes propagation of polarized light in discrete waveguides in the presence of the four-wave mixing. The energy and power conservation laws enable the formulation of the equilibrium properties of the polarization state in terms of the Gibbs measure with positive temperature. The transition line T=∞ is established beyond which the discrete vector solitons are created. Also in the limit of the large nonlinearity an analytical expression for the distribution of Stokes parameters is obtained, which is found to be dependent only on the statistical properties of the initial polarization state and not on the strength of nonlinearity. The evolution of the system to the final equilibrium state is shown to pass through the intermediate stage when the energy exchange between the waveguides is still negligible. The distribution of the Stokes parameters in this regime has a complex multimodal structure strongly dependent on the nonlinear coupling coefficients and the initial conditions.

Nanophotonics of optical fibers

This review is concerned with nanoscale effects in highly transparent dielectric photonic structures fabricated from optical fibers. In contrast to those in plasmonics, these structures do not contain metal particles, wires, or films with nanoscale dimensions. Nevertheless, a nanoscale perturbation of the fiber radius can significantly alter their performance. This paper consists of three parts. The first part considers propagation of light in thin optical fibers (microfibers) having the radius of the order of 100 nanometers to 1 micron. The fundamental mode propagating along a microfiber has an evanescent field which may be strongly expanded into the external area. Then, the cross-sectional dimensions of the mode and transmission losses are very sensitive to small variations of the microfiber radius. Under certain conditions, a change of just a few nanometers in the microfiber radius can significantly affect its transmission characteristics and, in particular, lead to the transition from the waveguiding to non-waveguiding regime. The second part of the review considers slow propagation of whispering gallery modes in fibers having the radius of the order of 10–100 microns. The propagation of these modes along the fiber axis is so slow that they can be governed by extremely small nanoscale changes of the optical fiber radius. This phenomenon is exploited in SNAP (surface nanoscale axial photonics), a new platform for fabrication of miniature super-low-loss photonic integrated circuits with unprecedented sub-angstrom precision. The SNAP theory and applications are overviewed. The third part of this review describes methods of characterization of the radius variation of microfibers and regular optical fibers with sub-nanometer precision.

Fe-doped and -mediated graphitic carbon nitride nanosheets for enhanced photocatalytic performance under natural sunlight

Herein, we demonstrate the synthesis of highly efficient Fe-doped graphitic carbon nitride (g-C3N4) nanosheets via a facile and cost effective method. The synthesized Fe-doped g-C3N4 nanosheets were well characterized by various analytical techniques. The results revealed that the Fe exists mainly in the +3 oxidation state in the Fe-doped g-C3N4 nanosheets. Fe doping of g-C3N4 nanosheets has a great influence on the electronic and optical properties. The diffuse reflectance spectra of Fe-doped g-C3N4 nanosheets exhibit red shift and increased absorption in the visible light range, which is highly beneficial for absorbing the visible light in the solar spectrum. More significantly, the Fe-doped g-C3N4 nanosheets exhibit greatly enhanced photocatalytic activity for the degradation of Rhodamine B under sunlight irradiation. The photocatalytic activity of 2 mol% Fe-doped g-C3N4 nanosheets is almost 7 times higher than that of bulk g-C3N4 and 4.5 times higher than that of pure g-C3N4 nanosheets. A proposed mechanism for the enhanced photocatalytic activity of Fe-doped g-C3N4 nanosheets was investigated by trapping experiments. The synthesized photocatalysts are highly stable even after five successive experimental runs. The enhanced photocatalytic performance of Fe-doped g-C3N4 nanosheets is due to high visible light response, large surface area, high charge separation and charge transfer. Therefore, the Fe-doped g-C3N4 photocatalyst is a promising candidate for energy conversion and environmental remediation.

The effect of sexist attitudes on the perception of visual artists by community college and university students

This study compared the effects of sexist labeling on the perceptions of visual artists by the community college and university students and determined their sex role orientation. The 370 students were shown five slides of an artist's works and were given six versions of an artist's biography. It contained embedded sexual labeling (woman, girl, person/ she, man, guy, person/he). The Artist Evaluation Questionnaire was administered to the female and male community college and university students that required the students to evaluate the female and male artists on several aspects of affective and cognitive measures. The questionnaire consisted of 9 items that had to be rated by the participants. In addition, the students filled out the Demographic Questionnaire and the BEM Sex Role Inventory, titled the Attitude Questionnaire. The Analysis of Variance testing procedures were administered to analyze the responses. The results disclosed gender differences in students' ratings. The female artist's work, when the artist was referred to by the neutral sexual label, "person", received significantly higher ratings from the female students. The male students gave the female artist her highest ratings when she was referred to by the low status sexual label, "girl". Both sexes did not express statistically significant preferences for any of the male sexual labels. Gender difference became apparent when it was found that female students rated both sexes equally, and their ratings were lower than those of the male students. The male students rated the female artist's work higher than the work of the male artist. The analysis of the sex role inventory questionnaire revealed the absence of the feminine (expressive) and masculine (instrumental) personalities among the students. The personalities of almost all the students were androgynous, with a few within the range of the near feminine, and a few within the range of the near masculine. The study reveals that there are differences in perception of sexual labels among the community college and university students.

Data compilation on the biological response to ocean acidification: environmental and experimental context of data sets and related literature

The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

Simulação de desempenho luminoso para salas de aula em Natal-RN

The city of Natal has a significant daylight availability, although it use isn’t systematically explored in schools architecture. In this context, this research aims to determine procedures for the analysis of the daylight performance in school design in Natal-RN. The method of analysis is divided in Visible Sky Factor (VSF), simulating and analyzing the results. The annual variation of the daylight behavior requires the adoption of dynamic simulation as data procedure. The classrooms were modelled in SketchUp, simulated in Daysim program and the results were assessed by means of spreadsheets in Microsoft Excel. The classrooms dimensions are 7.20mx 7.20m, with windows-to-wall-ratio (WWR) of 20%, 40% and 50%, and with different shading devices, such as standard horizontal overhang, sloped overhang, standard horizontal overhang with side view protection, standard horizontal overhang with a dropped edge, standard horizontal overhang with three horizontal louvers, double standard horizontal overhang, double standard horizontal overhang with three horizontal louvers, plus the use of shelf light in half the models with WWR of 40% and 50%. The data was organized in spreadsheets, with two intervals of UDI: between 300lux and 2000 lux and between 300lux and 3000lux. The simulation was performed with the weather file of 2009 to the city of NatalRN. The graphical outputs are illuminance curves, isolines of UDI among 300lux and 2000 lux and tables with index of occurrences of glare and to an UDI among 300lux 3000lux. The best UDI300-2000lux performance was evidenced to: Phase 1 (models with WWR of 20%), Phase 2 (models with WWR of 40% and 50% with light shelf). The best UDI300-3000lux performance was evidenced to: Phase 1 (models with WWR of 20% and 40% with light shelf) and Phase 2 (models with WWR of 40% and 50% with light shelf). The outputs prove that the daylight quality mainly depends on the shading system efficacy to avoid the glare occurrence, which determines the daylight discomfort. The bioclimatic recommendations of big openings with partial shading (with an opening with direct sunlight) resulted in illuminances level higher than the acceptable upper threshold. The improvement of the shading system percentage (from 73% to 91%) in medium-size of openings (WWR 40% and 50%) reduced or eliminate the glare occurrence without compromising the daylight zone depth (7.20m). The passive zone was determined for classrooms with satisfactory daylight performance, it was calculated the daylight zone depth rule-of-thumb with the ratio between daylight zone depth and the height of the window for different size of openings. The ratio ranged from 1.54 to 2.57 for WWR of 20%, 40% and 50% respectively. There was a reduction or elimination of glare in the passive area with light shelf, or with awning window shading.

Os limites do poder regulamentar do Conselho Nacional de Justiça no contexto do Estado constitucional brasileiro

The creation of the National Council of Justice (CNJ) through the Constitutional Amendment nº 45/2004, derived from countless gaps in Brazilian law, mainly relating to procedural delays, ineffectiveness of judicial decisions, and the lack of mechanisms that enable, effectively, disciplinary accountability of judges. The council is constitutionally designed as a member of the Judiciary, which has administrative nature and laid assignments in art. 103-B, § 4 of the current Constitution, among which is to edit regulations to instrument its performance. However, since it came into force, the amendment raised extensive discussions, linked in particular to the constitutionality of the CNJ, which was made through the direct action of unconstitutionality nº 3367, against the alleged violation of the principles of separation of powers and federative form, as well as the limits of its regulatory powers, as has fanned out in ADI nº 3823/ DF, this one dealing on Resolution nº 07, which regulates the seal of nepotism practice in the judiciary. However, despite the Supreme Court has already pronounced on the matter, recognizing the constitutionality of the council, as well as the resolution already said, the debate is in a state of latency, and may erupt again with each new manifestation of regulatory CNJ, given the lack of agreement between doctrine and jurisprudence around the constitutional treatment of its regulatory powers. In this context undeniably reflection on the definition of the regulatory power of the CNJ, presents itself as extremely relevant, and current, in particular in the ambience of the Constitutional Rule of Law, where he strives for legal certainty and consolidation of regulatory institutions. So that it could reach a satisfactory result, skilled at resolving the problems raised, the present study analyzed the reasons that gave rise to the creation of the CNJ, demonstrating their indispensability, but also sought to characterize the status of their administrative and constitutional body, noting finally, the compatibility of its regulatory activities to constitutional principles. From this perspective, we adopted the deductive method and carried out research and bibliographic nature documentary.

Modelagem dos efeitos da irradiação luminosa no cérebro de camundongos e rastreamento de neurônios durante experimentos de microscopia de fluorescência

The fluorescent proteins are an essential tool in many fields of biology, since they allow us to watch the development of structures and dynamic processes of cells in living tissue, with the aid of fluorescence microscopy. Optogenectics is another technique that is currently widely used in Neuroscience. In general, this technique allows to activate/deactivate neurons with the radiation of certain wavelengths on the cells that have ion channels sensitive to light, at the same time that can be used with fluorescent proteins. This dissertation has two main objectives. Initially, we study the interaction of light radiation and mice brain tissue to be applied in optogenetic experiments. In this step, we model absorption and scattering effects using mice brain tissue characteristics and Kubelka-Munk theory, for specific wavelengths, as a function of light penetration depth (distance) within the tissue. Furthermore, we model temperature variations using the finite element method to solve Pennes’ bioheat equation, with the aid of COMSOL Multiphysics Modeling Software 4.4, where we simulate protocols of light stimulation tipically used in optogenetics. Subsequently, we develop some computational algorithms to reduce the exposure of neuron cells to the light radiation necessary for the visualization of their emitted fluorescence. At this stage, we describe the image processing techniques developed to be used in fluorescence microscopy to reduce the exposure of the brain samples to continuous light, which is responsible for fluorochrome excitation. The developed techniques are able to track, in real time, a region of interest (ROI) and replace the fluorescence emitted by the cells by a virtual mask, as a result of the overlay of the tracked ROI and the fluorescence information previously stored, preserving cell location, independently of the time exposure to fluorescent light. In summary, this dissertation intends to investigate and describe the effects of light radiation in brain tissue, within the context of Optogenetics, in addition to providing a computational tool to be used in fluorescence microscopy experiments to reduce image bleaching and photodamage due to the intense exposure of fluorescent cells to light radiation.

O ensino de arte pós-moderno na arte de Daniel Francisco de Souza

This thesis presents a research that links cultural history and visual culture in a sociobiographical approach. It gives a “political treatment” to the educational experience in the transition of art teaching from the modern to the postmodern. By taking into account my experiences as an educator and the poetic practice in Daniel Francisco de Souza’s visual art, I propose a dialogue with his art and a series of visual narratives this artist/student produced at the time of his education and recently. Such visual narratives were taken as research source and research subject. They were created in a rural setting in dialogue with formal art teaching in two phases: 1992–6, when Daniel Fran cisco attended elementary school in the rural area of Uberlândia, MG; and 2008–10, when he attended Visual Arts graduation at Federal University of Uberlândia city. I analyze historical processes related to art and teaching, from the early sixteenth century to the present times, to realize residues in students’ poetic experiences. I relate Brazilian educational public policies with experi- ences in that rural school. I try to show the extent to which our educational practices triggered experiences — from ones common to intense ones — and promoted forms of “emancipation-knowledge” or “regulation-knowledge” and how the “selective tradition” was and how art predetermined history images gave way to everyday visual references, pointing to the “broad field” of visual culture. I make an effort to show Daniel Francisco’s work as an adult by tak- ing it according to different approaches. In a poetic reading, first, I emphasixe the material and the symbolic in his art. In a second look, I approach his work through the intertwining experiences of three characters from different times and places that participated in the making of his art: the artist farmer, the artist teacher and the teacher researcher. I assume the existence of a mutual cultural incompleteness in these three characters; which means that parts of their “structures of feeling” built on the interrelationship among them are part of the artist’ work as a historical content decanted. Thirdly, I demonstrate how the artist sees his place as a key re ference to his poetic creation. His work does not reflect the rural bucolic as something untouched. In showing the difficulty in distinguishing the archaic residual, I identify emerging issues in his work. I conclude that the artist — Daniel Francisco — and the researcher — myself — present maverick features: both are scavengers; their productions approach the working with scraps in art and in the academy; even momentarily, they live in exile in the warmth of the borders or the edges, from where one sees the center clearly. In these spaces, when certain structures and normative codes enter into coalition, they fragment pre-established strategies and stimulate the creation of survival tactics.

Photoacoustic tomography: principles and advances.

Photoacoustic tomography (PAT) is an emerging imaging modality that shows great potential for preclinical research and clinical practice. As a hybrid technique, PAT is based on the acoustic detection of optical absorption from either endogenous chromophores, such as oxy-hemoglobin and deoxy-hemoglobin, or exogenous contrast agents, such as organic dyes and nanoparticles. Because ultrasound scatters much less than light in tissue, PAT generates high-resolution images in both the optical ballistic and diffusive regimes. Over the past decade, the photoacoustic technique has been evolving rapidly, leading to a variety of exciting discoveries and applications. This review covers the basic principles of PAT and its different implementations. Strengths of PAT are highlighted, along with the most recent imaging results.

Los números cuentan. Sub-representación de la obra artística de mujeres creadoras en museos y centros de arte contemporáneos

Este artículo cuantifica la presencia de obra artística de mujeres artistas en 21 museos y centros de arte contemporáneo españoles. Los resultados constatan una nítida sub-representación de la obra exhibida, por debajo del 20 por ciento. ¿Por qué sucede esto?, ¿diferencial potencial artístico de mujeres y hombres?, ¿superioridad masculina?, ¿discriminación? o ¿un sistema de arte con sesgo androcéntrico? En estas páginas se discute sobre la presencia de varios factores para explicar la brecha de género y se reclama, de las administraciones públicas y las instituciones de gestión cultural, el cumplimiento de la Ley para la Igualdad para garantizar la paridad.

Del bodegón a la basura. Representaciones de alimentos en la historia del arte desde la perspectiva de la fotografía contemporánea

El artículo habla de la representación de alimentos en la Historia del Arte; estudia porqué las representaciones de comida tradicionalmente han sido consideradas como un género menor y plantea la hipótesis de su revitalización en el mercado del arte contemporáneo a través de la fotografía. Mediante el análisis de imágenes de comida en diferentes épocas, el texto explica que los bodegones casi siempre han sido símbolos de la superabundancia, presentando fundamentalmente alimentos, y en algunas ocasiones desperdicios. Continúa con la idea de que las sobras en las antigüedad eran orgánicas y sin embargo, en la actualidad los still life se han convertido en representaciones de basura, de desechos, y desperdicios en todas sus acepciones. El texto demuestra, mediante el análisis de algunas obras contemporáneas fotográficas, que el tema de la comida hoy es mucho más relevante de lo que la crítica de arte argumentaba en el pasado. Las imágenes de objetos conforman un sistema de representación y significado en continua evolución que es el reflejo de nuestra cultura. Estas fotografías nos hablan de sociología, política y economía mostrándonos en la actualidad el impacto que está sufriendo el medioambiente debido a nuestras rutinas cotidianas.

Estrategias museográficas actuales relacionadas con la museología crítica

Este artículo evita la mera disquisición teórica sobre museología crítica, sugiriendo en lugar de ello algunas pistas para calibrar su influencia en la praxis museal. Ante todo, se propone como emblemático de la museografía crítica el uso de interrogaciones en lugar de discursos asertivos; en segundo lugar, la sustitución de la impersonal autoridad institucional por prácticas participativas e interpretaciones compartidas, para dar idea de una variedad de opiniones, incluyendo las de gentes ajenas al museo; finalmente, es un rasgo distintivo el énfasis en la naturaleza subjetiva de los montajes museísticos, mostrando sus cambios a través de la historia, y señalando la autoría personal de las presentaciones y textos en el museo.