Demineralized dentin matrix technique - a comparison of different demineralizing solutions.

This study aimed to evaluate the microstructure formed after the chemical treatment of teeth, for the development of autogenous grafts from the demineralized dentin matrix (DDM) technique, in order to identify the most efficient demineralizing solution. The specimens, originating from the root and coronal portion, were submitted to ultrasonic cleaning and drying in an oven for 1h at 100 ºC. Then, the density was determined by Archimedes' principle for each specimen, using distilled water as immersion liquid. The samples were separated into five groups: Control group: negative control, Distilled water;EDTA group: positive control, trisodium EDTA; NaOCl group: 2.5% sodium hypochlorite; HCl-0.6M group: 0.6M hydrochloric acid; and H2O2/H2SO4 group: hydrogen peroxide and sulfuric acid. Each specimen was immersed for 1h in the corresponding group descaling solution at 60 ºC. Subsequently, the mass loss and density of the treated specimens were determined by Archimedes' principle. Ultimately, the specimens of each group were characterized by microtomography, Scanning Electron Microscopy, and Energy Dispersive Spectrometry X-ray (SEM-EDS). The results demonstrated that the H2O2/H2SO4 solution allowed the formation of interconnected micropores, suggesting better pore structures for application in scaffolds, when compared to the other studied solutions.

Demineralized dentin matrix technique - a comparison of different demineralizing solutions

Abstract This study aimed to evaluate the microstructure formed after the chemical treatment of teeth, for the development of autogenous grafts from the demineralized dentin matrix (DDM) technique, in order to identify the most efficient demineralizing solution. The specimens, originating from the root and coronal portion, were submitted to ultrasonic cleaning and drying in an oven for 1h at 100 ºC. Then, the density was determined by Archimedes' principle for each specimen, using distilled water as immersion liquid. The samples were separated into five groups: Control group: negative control, Distilled water;EDTA group: positive control, trisodium EDTA; NaOCl group: 2.5% sodium hypochlorite; HCl-0.6M group: 0.6M hydrochloric acid; and H2O2/H2SO4 group: hydrogen peroxide and sulfuric acid. Each specimen was immersed for 1h in the corresponding group descaling solution at 60 ºC. Subsequently, the mass loss and density of the treated specimens were determined by Archimedes' principle. Ultimately, the specimens of each group were characterized by microtomography, Scanning Electron Microscopy, and Energy Dispersive Spectrometry X-ray (SEM-EDS). The results demonstrated that the H2O2/H2SO4 solution allowed the formation of interconnected micropores, suggesting better pore structures for application in scaffolds, when compared to the other studied solutions.

Resumo Este estudo teve como objetivo avaliar a microestrutura formada após o tratamento químico em dentes, para o desenvolvimento de enxertos autógenos a partir da técnica de matriz de dentina desmineralizada (DDM), a fim de identificar a solução desmineralizante mais eficiente. Os espécimes, provenientes da raiz e porção coronal, foram submetidos à limpeza ultrassônica e secagem em estufa por 1h a 100 ºC. Em seguida, a densidade foi determinada pelo princípio de Arquimedes para cada espécime, utilizando água destilada como líquido de imersão. As amostras foram separadas em cinco grupos: Controle: controle negativo, Água destilada; EDTA: controle positivo, EDTA trissódico; NaOCl: hipoclorito de sódio 2,5%; HCl-0.6M: ácido clorídrico 0,6M; e H2O2/H2SO4: peróxido de hidrogênio e ácido sulfúrico. Cada espécime foi imerso por 1h na solução descalcificante de grupo correspondente a 60 ºC. Posteriormente, a perda de massa e a densidade dos espécimes tratados foram determinadas pelo princípio de Arquimedes. Por fim, os espécimes de cada grupo foram caracterizados por microtomografia, microscopia eletrônica de varredura e espectrometria de energia dispersiva de raios-X (SEM-EDS). Os resultados demonstraram que a solução H2O2/H2SO4 permitiu a formação de microporos interligados, sugerindo melhores estruturas de poros para aplicação em scaffolds, quando comparada às demais soluções estudadas.

Crystal nucleation in a glass during relaxation well below Tg.

Until quite recently, in almost all papers on crystal nucleation in glass-forming substances, it was assumed that nucleation proceeds in a completely relaxed supercooled liquid and, hence, at constant values of the critical parameters determining the nucleation rate for any given set of temperature, pressure, and composition. Here, we analyze the validity of this hypothesis for a model system by studying nucleation in a lithium silicate glass treated for very long times (up to 250 days) in deeply supercooled states, reaching 60 K below the laboratory glass transition temperature, Tg. At all temperatures in the considered range, T < Tg, we observed an enormous difference between the experimental number of nucleated crystals, N(t), and its theoretically expected value computed by assuming the metastable state of the relaxing glass has been reached. Analyzing the origin of this discrepancy, we confirmed that the key parameters determining the nucleation rates change with time as a result of the glass relaxation process. Finally, we demonstrate that, for temperatures below 683 K, this particular glass almost fully crystallizes prior to reaching the ultimate steady-state nucleation regime (e.g., at 663 K, it would take 176 years for the glass to reach 99% crystallization, while 2600 years would be needed for complete relaxation). This comprehensive study proves that structural relaxation strongly affects crystal nucleation in deeply supercooled states at temperatures well below Tg; hence, this phenomenon has to be accounted for in any crystal nucleation model.

Effect of the Process Parameters on the Adhesive Strength of Dissimilar Polymers Obtained by Multicomponent Injection Molding.

The growing demand in the consumer market for products with sustainable technologies has motivated new applications using overmolded natural fiber composites. Therefore, studies have been conducted mainly to understand the adhesive properties of overmolded parts. In the present study, a polypropylene (PP) composite with 30% coconut fibers without additives was developed with the aid of a corotating twin screw extruder. Subsequently, a multicomponent injection mold was developed based on the geometry of the ISO 527 type I specimen, in which samples overmolded with PP and PP-coconut-fiber composite, with the overlap in the central area, were obtained to evaluate the adhesive strength of dissimilar materials. The objective of this study was to evaluate the bond between PP and PP-coconut-fiber composite under different processing conditions using an adhesive strength testing device to perform a pure shear analysis. The experimental conditions followed a statistical design considering four factors in two levels and a significance level of 5%. The results indicated that adhesive strength increased significantly as the overlap area increased. It was observed that temperature and injection flow rate were the factors that most contributed to strengthening the bonds of dissimilar materials.

A multivariate analysis on spatiotemporal evolution of Covid-19 in Brazil.

This data-driven work aims to analyze and classify the spatiotemporal distribution of all Brazilian states considering data so diverse as the number of Covid-19 cases, deaths, confirmed cases per 100 k inhabitants, mortality per 100 k inhabitants and case fatality rates as health indicators. We also considered population, area and population density as geographic indicators. Finally, GDP and HDI were taken into account as economic and social criteria. For this task data were collected from April 3rd until August 8th, 2020, corresponding to epidemiological weeks 14-32, reaching three million cases and a hundred thousand deaths. With this data it was possible to classify Brazilian states using multivariate methods into possible groups by means of non-hierarchical (k-means) cluster as well as factor analysis. It was possible to group all states plus the Federal District into five clusters, taking into account these 10 variables over the first five months of the epidemic. Group changes between states were observed over time and clusters, and between three and four factors were found. However, even with great difference on health indicators during days, the number of clusters remains fixed. Also, São Paulo and Rio de Janeiro states were ranked at top list taking into account all epidemiological weeks. Correlations were observed between variables, such as the number of Covid cases and deaths with GDP for most of epidemiological weeks. Some clusters were more critical due to specific variables, including cities that are main hotspots. These multivariate findings would provide a comprehensive description of the ongoing Covid-19 epidemic and may help to guide subsequent studies to understand and control virus transmission.

Tribological Investigations on Tool Surfaces for Temperature-Supported Forming of Magnesium AZ31 Sheets.

Aiming to decrease friction coefficient ( µ ) during the forming of magnesium alloy sheets, nine (9) tools with different hole geometries in their surface (flat, elliptical, and circular) were manufactured from steel Boehler W400 VMR (as known as DIN 1.2343). Tribological investigations were accomplished on a strip drawing machine at 288 °C without lubricants. When compared with a standard tool (surface flat), on average, tools with circular geometries in their surface showed the smallest friction coefficient, while tools with elliptical geometries shown higher. The friction coefficient also was confronted with the ratio between area occupied by holes in the surface of the tool and the total tool surface (i.e., factor f (%)), hole diameter (Ø), and the distance between circle centers (d(c,c)). Principal Component Analysis (PCA) complemented the experimental approach. In summary, both approaches (experimental and theoretical) indicated that the manufactured tool with circular geometries on its surface presented lower friction coefficient values on the forming processes of the magnesium AZ31 sheets.

Improvement of Baker's yeast-based fuel cell power output by electrodes and proton exchange membrane modification.

The production of more efficient yeast-based fuel cells (YFCs) depends on a combination of effective proton exchange membranes, electron mediators and current collectors. The adhesion of organisms on electrode surface plays a key role in the electron transfer process optimizing the generated power density. In this work, it is reported the preparation of a new YFC prototype using membranes of polyvinyl alcohol/ phosphoric acid and anodes of carbon nanotubes/polyurethane. The high surface area for yeast adhesion and the strong interaction established between cells/carbon nanotubes favor the energy generation in fuel cell. To evaluate the influence of external mediators and the consumption of feed solution (glucose) on performance of YFC, the kinetics of current generation of resulting fuel cells was analyzed. Results reveal that increases in the impedance of electrodes on generated power can be minimized by periodical infusion of feed fuel, preserving 70% of maximum power, representing an important condition for prolonged activity of fuel cell.

Elemental and cooperative diffusion in a liquid, supercooled liquid and glass resolved.

The diffusion mechanisms controlling viscous flow, structural relaxation, liquid-liquid phase separation, crystal nucleation, and crystal growth in multicomponent glass-forming liquids are of great interest and relevance in physics, chemistry, materials, and glass science. However, the diffusing entities that control each of these important dynamic processes are still unknown. The main objective of this work is to shed some light on this mystery, advancing the knowledge on this phenomenon. For that matter, we measured the crystal growth rates, the viscosity, and lead diffusivities in PbSiO3 liquid and glass in a wide temperature range. We compared our measured values with published data covering 16 orders of magnitude. We suggest that above a certain temperature range Td (1.2Tg-1.3Tg), crystal growth and viscous flow are controlled by the diffusion of silicon and lead. Below this temperature, crystal growth and viscous flow are more sluggish than the diffusion of silicon and lead. Therefore, Td marks the temperature where decoupling between the (measured) cationic diffusivity and the effective diffusivities calculated from viscosity and crystal growth rates occurs. We reasonably propose that the nature or size of the diffusional entities controlling viscous flow and crystal growth below Td is quite different; the slowest is the one controlling viscous flow, but both processes require cooperative movements of some larger structural units rather than jumps of only one or a few isolated atoms.

A Literature Investigation about Electrospinning and Nanofibers: Historical Trends, Current Status and Future Challenges.

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 5(th), 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.

Isolated median neuropathy as the first symptom of leprosy.

INTRODUCTION: Focal peripheral neuropathy of the median nerve is mainly caused by a traumatic event or pressure, but it may also be produced by systemic illnesses. Among the latter, leprosy is a rare cause. METHODS: Six cases of isolated median neuropathy as the first sign of leprosy were selected from patients with an exclusively neurological complaint as the initial symptom. The patients, evaluated at the National Leprosy Reference Center in Rio de Janeiro, Brazil, followed routine and specialized procedures. RESULTS: Three of the patients had pure neural leprosy, and 3 had skin lesions. Clinical median nerve function impairment was confirmed by neurophysiological testing and histopathology. Both mononeuritis and mononeuritis multiplex were observed. CONCLUSIONS: This case series demonstrates an additional form of presentation of leprosy, which, if not diagnosed and treated in time, may lead to permanent disability.

Old sertaneja song: narrating a backcountry life story about aging process in homosexuality / Velha canção sertaneja: narrando história de vida interiorana sobre o processo de envelhecimento nas homossexualidades

In contemporary times, the discussions about aging become very relevant as a consequence of the increased visibility of the old age issues presented in daily life. Many investigations and statistics bring out the growing number of people entering the so-called third age. This reality is mobilizing all social spheres in order to produce interventional strategies in agreement with the specificities required by this population, as far as what this public can revert back to the society. However, most of these studies seek to identify and locate this population in plans of life that can often suggest the reification of norms and stereotypes that delimit what become old mean or just discuss the practice of medical care. This paper invests in questioning of modes of subjectification and lifestyles, from the intersections between generation (aging), homosexuality (sexuality and gender) and territoriality (provincial town). It presents an analysis of a life story from the perspective of cultural studies and sexualities and gender to capture the subjective lines which construct subjects and discourses, indicating social practices, modes of subjectification and social, historical, political and cultural conjunctures of determined contexts.

Na contemporaneidade, o entorno e as discussões sobre o envelhecer tornaram-se relevantes a partir da visibilidade apresentada no cotidiano. Muitas investigações e dados estatísticos trazem à tona o número crescente de pessoas que adentram a dita terceira idade. Essa realidade vem mobilizando todas as esferas sociais no intuito de produzir estratégias e condições interventivas condizentes com as especificidades requeridas por essa população, tanto quanto o que esse público pode reverter para a sociedade. Entretanto, é fato que grande parte desses estudos busca identificar e localizar essa população em planos de vida que, muitas vezes, podem sugerir a reificação de estereótipos e normativas que circunscrevem o tornar-se velho ou apenas discutem a prática do cuidar. O objetivo deste trabalho investe na problematização de modos de subjetivação e estilos de vida, partindo das intersecções entre geração (envelhecer), homossexualidade (sexualidade e gênero) e territorialidade (município interiorano). Para tanto, apresenta a análise de narrativa de uma história de vida à luz dos estudos culturais, das sexualidades e dos gêneros para captar as linhas subjetivas que constroem sujeitos e discursos e que, consequentemente, indicam práticas sociais, modos de subjetivação e conjunturas sócio-históricos, culturais e políticos de determinados contextos.

"Old sertaneja song": narrating a backcountry life story about aging process in homosexuality / “Velha canção sertaneja”: narrando história de vida interiorana sobre o processo de envelhecimento nas homossexualidades

In contemporary times, the discussions about aging become very relevant as a consequence of the increased visibility of the old age issues presented in daily life. Many investigations and statistics bring out the growing number of people entering the so-called third age. This reality is mobilizing all social spheres in order to produce interventional strategies in agreement with the specificities required by this population, as far as what this public can revert back to the society. However, most of these studies seek to identify and locate this population in plans of life that can often suggest the reification of norms and stereotypes that delimit what become old mean or just discuss the practice of medical care. This paper invests in questioning of modes of subjectification and lifestyles, from the intersections between generation (aging), homosexuality (sexuality and gender) and territoriality (provincial town). It presents an analysis of a life story from the perspective of cultural studies and sexualities and gender to capture the subjective lines which construct subjects and discourses, indicating social practices, modes of subjectification and social, historical, political and cultural conjunctures of determined contexts.(AU)

Na contemporaneidade, o entorno e as discussões sobre o envelhecer tornaram-se relevantes a partir da visibilidade apresentada no cotidiano. Muitas investigações e dados estatísticos trazem à tona o número crescente de pessoas que adentram a dita terceira idade. Essa realidade vem mobilizando todas as esferas sociais no intuito de produzir estratégias e condições interventivas condizentes com as especificidades requeridas por essa população, tanto quanto o que esse público pode reverter para a sociedade. Entretanto, é fato que grande parte desses estudos busca identificar e localizar essa população em planos de vida que, muitas vezes, podem sugerir a reificação de estereótipos e normativas que circunscrevem o tornar-se velho ou apenas discutem a prática do cuidar. O objetivo deste trabalho investe na problematização de modos de subjetivação e estilos de vida, partindo das intersecções entre geração (envelhecer), homossexualidade (sexualidade e gênero) e territorialidade (município interiorano). Para tanto, apresenta a análise de narrativa de uma história de vida à luz dos estudos culturais, das sexualidades e dos gêneros para captar as linhas subjetivas que constroem sujeitos e discursos e que, consequentemente, indicam práticas sociais, modos de subjetivação e conjunturas sócio-históricos, culturais e políticos de determinados contextos.(AU)

Charge carrier mobility and concentration as a function of composition in AgPO3-AgI glasses.

Conductivity data of the xAgI(1 - x)AgPO(3) system (0 ≤ x ≤ 0.5) were collected in the liquid and glassy states. The difference in the dependence of ionic conductivity on temperature below and above their glass transition temperatures (T(g)) is interpreted by a discontinuity in the charge carrier's mobility mechanisms. Charge carrier displacement occurs through an activated mechanism below T(g) and through a Vogel-Fulcher-Tammann-Hesse mechanism above this temperature. Fitting conductivity data with the proposed model allows one to determine separately the enthalpies of charge carrier formation and migration. For the five investigated compositions, the enthalpy of charge carrier formation is found to decrease, with x, from 0.86 to 0.2 eV, while the migration enthalpy remains constant at ≈0.14 eV. Based on these values, the charge carrier mobility and concentration in the glassy state can then be calculated. Mobility values at room temperature (≈10(-4) cm(2) V(-1) s(-1)) do not vary significantly with the AgI content and are in good agreement with those previously measured by the Hall-effect technique. The observed increase in ionic conductivity with x would thus only be due to an increase in the effective charge carrier concentration. Considering AgI as a weak electrolyte, the change in the effective charge carrier concentration is justified and is correlated to the partial free energy of silver iodide forming a regular solution with AgPO(3).

“Velha canção sertaneja”: narrando história de vida interiorana sobre o processo de envelhecimento nas homossexualidades / "Old sertaneja song": narrating a backcountry life story about aging process in homosexuality

Na contemporaneidade, o entorno e as discussões sobre o envelhecer tornaram-se relevantes a partir da visibilidade apresentada no cotidiano. Muitas investigações e dados estatísticos trazem à tona o número crescente de pessoas que adentram a dita terceira idade. Essa realidade vem mobilizando todas as esferas sociais no intuito de produzir estratégias e condições interventivas condizentes com as especificidades requeridas por essa população, tanto quanto o que esse público pode reverter para a sociedade. Entretanto, é fato que grande parte desses estudos busca identificar e localizar essa população em planos de vida que, muitas vezes, podem sugerir a reificação de estereótipos e normativas que circunscrevem o tornar-se velho ou apenas discutem a prática do cuidar. O objetivo deste trabalho investe na problematização de modos de subjetivação e estilos de vida, partindo das intersecções entre geração (envelhecer), homossexualidade (sexualidade e gênero) e territorialidade (município interiorano). Para tanto, apresenta a análise de narrativa de uma história de vida à luz dos estudos culturais, das sexualidades e dos gêneros para captar as linhas subjetivas que constroem sujeitos e discursos e que, consequentemente, indicam práticas sociais, modos de subjetivação e conjunturas sócio-históricos, culturais e políticos de determinados contextos.(AU)

In contemporary times, the discussions about aging become very relevant as a consequence of the increased visibility of the old age issues presented in daily life. Many investigations and statistics bring out the growing number of people entering the so-called third age. This reality is mobilizing all social spheres in order to produce interventional strategies in agreement with the specificities required by this population, as far as what this public can revert back to the society. However, most of these studies seek to identify and locate this population in plans of life that can often suggest the reification of norms and stereotypes that delimit what become old mean or just discuss the practice of medical care. This paper invests in questioning of modes of subjectification and lifestyles, from the intersections between generation (aging), homosexuality (sexuality and gender) and territoriality (provincial town). It presents an analysis of a life story from the perspective of cultural studies and sexualities and gender to capture the subjective lines which construct subjects and discourses, indicating social practices, modes of subjectification and social, historical, political and cultural conjunctures of determined contexts.(AU)

Dynamic processes in a silicate liquid from above melting to below the glass transition.

We collect and critically analyze extensive literature data, including our own, on three important kinetic processes--viscous flow, crystal nucleation, and growth--in lithium disilicate (Li(2)O·2SiO(2)) over a wide temperature range, from above T(m) to 0.98T(g) where T(g) ≈ 727 K is the calorimetric glass transition temperature and T(m) = 1307 K, which is the melting point. We found that crystal growth mediated by screw dislocations is the most likely growth mechanism in this system. We then calculated the diffusion coefficients controlling crystal growth, D(eff)(U), and completed the analyses by looking at the ionic diffusion coefficients of Li(+1), O(2-), and Si(4+) estimated from experiments and molecular dynamic simulations. These values were then employed to estimate the effective volume diffusion coefficients, D(eff)(V), resulting from their combination within a hypothetical Li(2)Si(2)O(5) "molecule". The similarity of the temperature dependencies of 1/η, where η is shear viscosity, and D(eff)(V) corroborates the validity of the Stokes-Einstein/Eyring equation (SEE) at high temperatures around T(m). Using the equality of D(eff)(V) and D(eff)(η), we estimated the jump distance λ ~ 2.70 Å from the SEE equation and showed that the values of D(eff)(U) have the same temperature dependence but exceed D(eff)(η) by about eightfold. The difference between D(eff)(η) and D(eff)(U) indicates that the former determines the process of mass transport in the bulk whereas the latter relates to the mobility of the structural units on the crystal/liquid interface. We then employed the values of η(T) reduced by eightfold to calculate the growth rates U(T). The resultant U(T) curve is consistent with experimental data until the temperature decreases to a decoupling temperature T(d)(U) ≈ 1.1-1.2T(g), when D(eff)(η) begins decrease with decreasing temperature faster than D(eff)(U). A similar decoupling occurs between D(eff)(η) and D(eff)(τ) (estimated from nucleation time-lags) but at a lower temperatureT(d)(τ) ≈ T(g). For T > T(g) the values of D(eff)(τ) exceed D(eff)(η) only by twofold. The different behaviors of D(eff)(τ)(T) and D(eff)(U)(T) are likely caused by differences in the mechanisms of critical nuclei formation. Therefore, we have shown that at low undercoolings, viscosity data can be employed for quantitative analyses of crystal growth rates, but in the deeply supercooled liquid state, mass transport for crystal nucleation and growth are not controlled by viscosity. The origin of decoupling is assigned to spatially dynamic heterogeneity in glass-forming melts.

“Velha canção sertaneja”: narrando história de vida interiorana sobre o processo de envelhecimento nas homossexualidades / "Old sertaneja song": narrating a backcountry life story about aging process in homosexuality

Na contemporaneidade, o entorno e as discussões sobre o envelhecer tornaram-se relevantes a partir da visibilidade apresentada no cotidiano. Muitas investigações e dados estatísticos trazem à tona o número crescente de pessoas que adentram a dita terceira idade. Essa realidade vem mobilizando todas as esferas sociais no intuito de produzir estratégias e condições interventivas condizentes com as especificidades requeridas por essa população, tanto quanto o que esse público pode reverter para a sociedade. Entretanto, é fato que grande parte desses estudos busca identificar e localizar essa população em planos de vida que, muitas vezes, podem sugerir a reificação de estereótipos e normativas que circunscrevem o tornar-se velho ou apenas discutem a prática do cuidar. O objetivo deste trabalho investe na problematização de modos de subjetivação e estilos de vida, partindo das intersecções entre geração (envelhecer), homossexualidade (sexualidade e gênero) e territorialidade (município interiorano). Para tanto, apresenta a análise de narrativa de uma história de vida à luz dos estudos culturais, das sexualidades e dos gêneros para captar as linhas subjetivas que constroem sujeitos e discursos e que, consequentemente, indicam práticas sociais, modos de subjetivação e conjunturas sócio-históricos, culturais e políticos de determinados contextos...

In contemporary times, the discussions about aging become very relevant as a consequence of the increased visibility of the old age issues presented in daily life. Many investigations and statistics bring out the growing number of people entering the so-called third age. This reality is mobilizing all social spheres in order to produce interventional strategies in agreement with the specificities required by this population, as far as what this public can revert back to the society. However, most of these studies seek to identify and locate this population in plans of life that can often suggest the reification of norms and stereotypes that delimit what become old mean or just discuss the practice of medical care. This paper invests in questioning of modes of subjectification and lifestyles, from the intersections between generation (aging), homosexuality (sexuality and gender) and territoriality (provincial town). It presents an analysis of a life story from the perspective of cultural studies and sexualities and gender to capture the subjective lines which construct subjects and discourses, indicating social practices, modes of subjectification and social, historical, political and cultural conjunctures of determined contexts...

Does viscosity describe the kinetic barrier for crystal growth from the liquidus to the glass transition?

An analysis of the kinetic coefficient of crystal growth U(kin), recently proposed by Ediger et al. [J. Chem. Phys. 128, 034709 (2008)], indicates that the Stokes-Einstein/Eyring (SE/E) equation does not describe the diffusion process controlling crystal growth rates in fragile glass-forming liquids. U(kin) was defined using the normal growth model and tested for crystal data for inorganic and organic liquids covering a viscosity range of about 10(4)-10(12) Pa s. Here, we revisit their interesting finding considering two other models: the screw dislocation (SD) and the two-dimensional surface nucleated (2D) growth models for nine undercooled oxide liquids, in a wider temperature range, from slightly below the melting point down to the glass transition region T(g), thus covering a wider viscosity range: 10(1)-10(13) Pa s. We then propose and use normalized kinetic coefficients (M(kin)) for the SD and 2D growth models. These new kinetic coefficients restore the ability of viscosity to describe the transport part of crystal growth rates (M(kin)∼1/η and ξ∼1) from low to moderate viscosities (η<10(6) Pa s), and thus the SE/E equation works well in this viscosity range for all systems tested. For strong glasses, the SE/E equation works well from low to high viscosities, from the melting point down to T(g)! However, for at least three fragile liquids, diopside (kink at 1.08T(g), η=1.6×10(8) Pa s), lead metasilicate (kink at 1.14T(g), η=4.3×10(6) Pa s), and lithium disilicate (kink at 1.11T(g), η=1.6×10(8) Pa s), there are clear signs of a breakdown of the SE/E equation at these higher viscosities. Our results corroborate the findings of Ediger et al. and demonstrate that viscosity data cannot be used to describe the transport part of the crystal growth (via the SE/E equation) in fragile glasses in the neighborhood of T(g).

Charge carrier concentration and mobility in alkali silicates.

The respective contributions of the charge carrier concentration and mobility to the ionic conductivity in glasses remain an open question. In the present work we calculate these two parameters from conductivity data as a function of temperature below and above the glass transition temperature, T(g). The basic hypothesis assumes that ionic displacement results from the migration of cationic pairs formed by a partial dissociation, which is a temperature-activated process. Below T(g) their migration would follow a temperature-activated mechanism, while a free volume mechanism prevails above this temperature, leading to a deviation from the Arrhenius behavior. Expressions are formulated for the variation in ionic conductivity as a function of temperature in the supercooled and glassy states. Fitting the experimental data with the proposed expressions allows for the determination of characteristic parameters such as the charge carrier formation and migration enthalpies. Based on these values, it is then possible to calculate the charge carrier concentration and mobility in the entire temperature range. At room temperature, the mobility of effective charge carriers is estimated close to 10(-4) cm(2) s(-1) V(-1) for alkali disilicates glasses under study, while the ratio between the number of effective charge carriers and the total number of alkali cations is estimated to be from 10(-8) to 10(-10), comparable to the concentration of intrinsic defects in an ionic crystal or dissociated species from a weak electrolyte solution.

Existem consumidores de turismo LGBT na região norte do Paraná? Quem são e o que consomem? / Are there consumers of GLS tourism in the northern region of Paraná? Who are and what they consume?

A segmentação de mercado é uma estratégia amplamente utilizada na indústria turística, a qual permite uma distribuição mais equilibrada da concorrência e a possibilidade de se identificar e satisfazer necessidades específicas do público consumidor que aspira conquistar. O presente artigo pretende analisar práticas discursivas de homossexuais masculinos que frequentam eventos GLS na região norte do Paraná e que podem representar um nicho mercadológico importante para a construção de uma política de turismo GLS. Para tanto, utilizará teorias do saber em Turismo, assim como autores pós-estruturalistas das Ciências Humanas, visando a estabelecer a relação desse segmento turístico como um propulsor do mercado GLS, não somente no campo econômico (pink money), mas também na forma como as pessoas buscam prazer e lazeres específicos. (AU)

Market segmentation is a strategy widely used in tourism industry which allows a more balanced concurrency and the possibility to identify and satisfy the specific needs of the consuming public which aspires to achieve. This article analyzes the discursive practices of gay men who attend events GLS in northern Paraná, which may represent an important niche market in the construction of a GLS tourism policy. Therefore, it uses theories of knowledge in tourism as well as post-structuralist authors of the human sciences, aiming to establish the relationship of the tourism sector as a catalyst for the gay market, not only in the economic field (pink money) but also in the way people look for specific pleasure and leisure. (AU)