Sun exposure and sun protection habits among high-school adolescents in Porto Alegre, Brazil

Adolescents constitute an important audience for photoprotection programs. Sun exposure and sun protection habits acquired during adolescence have a significant impact on skin cancer incidence. We administered a questionnaire to 724 students about ultraviolet radiation effects, opinions about tanning, total time of sun exposure per day, photoprotection and activities in the sun. About 90% were aware of the association between sun exposure and skin cancer, and mass media was the main source of information. However, the great majority believed that tanning improved their appearance, and that it was worth taking the risk. The most prevalent outdoor activity among boys was sports; girls preferred walks and sunbathing. Sun exposure was significantly longer in summer, when 90% of the students went to the beach. About 47% reported sunscreen use in summer and only 3% reported using sunscreen during winter. These results emphasize the need for the promotion of photoprotective habits in our population and the importance of engaging physicians and school teachers in developing campaigns directed at this issue to achieve effective, long-lasting results. Adolescents are aware of the effects of ultraviolet radiation on the skin but campaigns have not successfully changed their sun exposure habits.     

Synthesis and characterization of epoxy-modified cement slurries--kinetic data at hardened slurries/HCl interfaces

In this study, two new epoxy-modified oilwell cement slurries were synthesized. All characterization measurements were performed and compared in relation to a standard cement slurry, which was synthesized using only cement and water. The XRD patterns, as well as TG/DTG and DSC analyses have suggested that portlandite (Ca(OH)2) and carbonate phases were not present in detectable amounts in the new cement slurries. The isothermal kinetic data of the interaction of HCl with the epoxy-modified cement were obtained using the batch mode from 25 to 55 degrees C. The kinetic data were best fitted to the second-order and the Avrami kinetic models, since differences between experimental and calculated values were lower for these models. The intraparticle diffusion model has pointed out that the new slurries present positive values for the parameter "C," which is related to higher boundary layer resistance to HCl diffusion into the internal parts of the slurries, in relation to the standard slurry. The characterization and the HCl interaction kinetic studies have suggested that the new cement slurries present good potential, from the chemical viewpoint, to be used in oilwell operations.     

Determination of kinetic parameters of Cu(II) interaction with chemically modified thin chitosan membranes

In this work, vanillin-modified thin chitosan membranes were utilized as adsorbents for the removal of Cu(II) from aqueous solutions. A rise of temperature accelerates mass transfer of Cu(II) to the membranes surfaces. The kinetic data did present a rough fit to the traditional Lagergren adsorption kinetic equations. An alternative Avrami kinetic equation was successfully fitted to the kinetic adsorption quantities. From this new equation, from one to three regions presenting distinct kinetic parameters were found, and the use of the parameter n was also related to the determination of the kinetic orders. Variations of the adsorption rate in relation to the contact time and the temperature were also calculated and are discussed.     

The use of freshwater fish scale of the species Leporinus elongatus as adsorbent for anionic dyes

Fish scale of the species Leporinus elongatus was tested as an adsorbent for anionic Remazol dyes. Characterization has suggested that hydroxyl, phosphate, amides I, II, and III, and carbonate groups are the potential sites of adsorption. From solution calorimetry, values of thermal effects, Q _int, and amount of dye that interacts, n _int, were determined. The adsorption order observed was Yellow-dye/scale?>?Red-dye/scale?>?Blue-dye/scale. The Q _int and n _int data were successfully adjusted to the Langmuir isotherm model. The dyes removals by fish scale are exothermic processes (from ?83 to ?199?kJ?mol^?1) with negative entropies and are thermodynamically spontaneous. The thermodynamic results suggest that the interactions at scale/anionic dye interfaces occur mainly by surface reactions. It was finding that fish scale is a new and suitable sorbent material for recovery and biosorption/adsorption of anionic dyes from aqueous solutions.     

Effects of lipopolysaccharide-induced inflammation on expression of growth-associated genes by corticospinal neurons

Background  

Inflammation around cell bodies of primary sensory neurons and retinal ganglion cells enhances expression of neuronal growth-associated genes and stimulates axonal regeneration. We have asked if inflammation would have similar effects on corticospinal neurons, which normally show little response to spinal cord injury. Lipopolysaccharide (LPS) was applied onto the pial surface of the motor cortex of adult rats with or without concomitant injury of the corticospinal tract at C4. Inflammation around corticospinal tract cell bodies in the motor cortex was assessed by immunohistochemistry for OX42 (a microglia and macrophage marker). Expression of growth-associated genes c-jun, ATF3, SCG10 and GAP-43 was investigated by immunohistochemistry or in situ hybridisation.     

Reapplication improves the amount of sunscreen, not its regularity, under real life conditions

The sun protection factor (SPF) of sunscreens is determined using samples applied with a thickness of 2 mg cm(-2). Sunscreen users, however, typically apply sunscreen nonuniformly and in smaller amounts. The objective of our study was to verify whether sunscreen reapplication increases the amount and regularity of the product on the skin. Volunteers were asked to apply an SPF 6 sunscreen on their forearms and reapply it 30 min later on one forearm. Tape-strips were used to collect five samples from two different sites on each forearm. The concentration of benzophenone-3 in the samples was measured and the total amount of sunscreen was estimated using high-performance liquid chromatography. The median amount of sunscreen film was 0.43 mg cm(-2) (0.17-1.07) after one application and 0.95 mg cm(-2) (0.18-1.91) after two applications (P = 0.002). No significant difference was found in the film uniformity. Though sunscreen reapplication increases the amount of product on the skin, levels are still lower than the recommended amount, confirming that the protection level is less than the product-stated SPF. Our results are the first in the literature to support the recommendation for reapplying sunscreens. Based on our results, we recommend that sunscreens be labeled using qualitative measures.     

The Interplay Between Gesture and Discourse as Mediating Devices in Collaborative Mathematical Reasoning:A Multimodal Approach

This article aims to identify the mathematical reasoning strategies expressed through gestures and speech used by two groups of sixth-grade pupils when solving a task related to the transition between two semiotic representations: figure and Cartesian diagram. The article also identifies the difficulties the pupils meet in the solution process. The analyses of the group dialogues focus particularly on the gesture dimension of deixis. The pupils in both groups have used the following deictic gestures: pointing, held-point, linear point-slide, and circular point-slide in their solution process, while repeated pointing has been identified only in one of the groups. These pointing gestures are related to the reasoning strategies: comparison of persons in the figure, coordination of two dimensions in the diagram, recapitulation and going to an extreme location. The pupils use the modalities of speech, gesture, and writing in order to solve the mathematical task. Their pointing gestures related to their use of reasoning strategies play a multifaceted role in developing collaborative mathematical reasoning in the two small groups.     

Zirconium phosphate changing hygroscopicity of polyamide-6 in nanocomposites PA-6/ZrP

Journal of Thermal Analysis and Calorimetry - Hygroscopicity can be understood as ability of any material to absorb water. This investigation aims to study the effect of lamellar zirconium...     

Probabilistic Inductive Classes of Graphs

A unifying framework—probabilistic inductive classes of graphs (PICGs)—is defined by imposing a probability space on the rules and their left elements from the standard notion of inductive class of graphs. The rules can model the processes creating real-world social networks, such as spread of knowledge, dynamics of acquaintanceships or sexual contacts, and emergence of clusters. We demonstrate the characteristics of PICGs by casting some well-known models of growing networks in this framework. Results regarding expected size and order are derived. For PICG models of connected and 2-connected graphs order, size and asymptotic degree distribution are presented. The approaches used represent analytic alternative to computer simulation, which is mostly used to obtain the properties of evolving graphs.