Silver (AgNPs) and gold (AuNPs) nanoparticles in aqueous solution were generated and stabilized using the 10-oxo-10H-dibenzene thiopyran-3-4-dicarboximide chitosan (TXICh) macrophotoinitiator. The photoinitiator and the nanoparticles in aqueous solution were characterized by UV-Vis spectroscopy and transmission electron microscopy (TEM). Pure TXICh in aqueous solution forms self-assembled particles with diameter around 30 nm. AgNPs were prepared using TXICh in the presence and absence of triethanolamine (TEOH). During irradiation, a broad band in the range of 410-415 nm was observed, corresponding to the plasmon absorption, indicating the AgNPs formation. TEM images revealed that the AgNPs had spherical shape in the absence and presence of TEOH. The synthesis of AgNPs in the presence of TEOH occurred rapidly (maximum conversion reached after 15 min), whereas in its absence 4 hours were required. The AgNPs prepared with TXICh/TEOH presented smaller and more uniform nanoparticles size. AuNPs were also prepared using TXICh as photoinitiator/stabilizer system. These nanoparticles showed an intense surface plasmon band at 530 nm and the TEM images revealed spherical particles of around 4 nm. These studies indicate that TXICh can act not only as a photoinitiator, but also as a stabilizer in the AgNPs and AuNPs formation.

Polyacrylic acid (PAA)/clay mineral (SWy-1) nanocomposites were prepared by intercalation in solution and their photostability was evaluated. For the nanocomposite films containing 5, 10 and 20 wt % in SWy-1 mass occurred intercalation along with some clay exfoliation, while for PAA/30%SWy-1, the intercalation of PAA chains into the clay interlayers was observed. Scanning Electron Microscopy (SEM) images of the films suggested that nanocomposite films are homogeneous, indicating efficient dispersion of the polymer matrix into the SWy-1 clay. The thermal degradation temperatures of depolymerisation for the nanocomposite films were higher (362-370 °C) than pure PAA (361 °C), which means that the presence of SWy-1 clay promotes thermal stabilization.The photooxidative degradation of pure PAA and nanocomposite films was followed using Size Exclusion Chromatography (SEC). The degradation rate constant for pure PAA was higher than nanocomposite films; therefore, the increase of SWy-1concentration detained the degradation of PAA. The presence of SWy-1 clay contributes for the photostabilization of the material. SWy-1 has ability to disperse the incident light as well as also to absorb part of the UV light instead of PAA, hence minimizing the degradation rate.

Experimental dental resins composed of triethyleneglycol dimethacrylate, urethane dimethacrylate, ethoxylated bisphenol-A-dimethacrylate and bisphenol A glycidyl methacrylate containing an organoclay as filler were prepared by photopolymerization. The addition of organoclay fillers results in slower polymerization rates (0.59 and 0.24 mol L-1 min-1, for the formulations without and with 15% of organoclay, respectively) and lower degrees of conversion (0.50 and 0.35 for the formulations without and with 15% of organoclay), as determined by photocalorimetry. The influence of the organoclay on the thermal and mechanical properties of the resins was evaluated using thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) techniques. The (tan δ) and E´ curves indicate the formation of more rigid materials and the damping curve data indicates more homogeneous materials. An increase of storage modulus, E’, was observed for composites with the higher organoclay filler contents. These effects are due to the higher viscosity of the systems with organoclay, resulting in a lower mobility of the radicals during the propagation step of polymerization, as well as to the scattering of the incident photopolymerizing radiation, which lowers the amount of initiation centres.

Compósitos de poli(óxido de etileno) (PEO) com argila montmorilonita SWy-1 e estabilizantes (2-hidroxibenzofenona e tinuvin 770) foram preparados pelo método de intercalação em solução. Os filmes obtidos foram expostos a irradiação UV, e os produtos da fotodegradação foram monitorados por FTIR (Fourier Transform Infrared Spectroscopy, ou Espectroscopia no infravermelho por transformada de Fourier) e SEC (Size Exclusion Chromatography, ou cromatografia de exclusão por tamanho). O PEO puro apresentou maior coeficiente de degradação, kd, comparado com as demais amostras. O sistema que apresentou o menor valor para o coeficiente de degradação (kd = 1,9×10–6 mol g–1 h-1) foi o compósito de PEO/5%SWy-1 com 0,25% de tinuvin 770. Nesse caso, a estabilização da matriz de PEO pode ser atribuída à argila juntamente com o tinuvin 770. A argila dispersa e absorve a irradiação UV, e o tinuvin age como estabilizante do tipo HALS (do inglês hindered amine light stabilizer, ou estabilizantes à luz tipo aminas impedidas).

Poly(ethylene oxide) (PEO) with SWy-1 montmorillonite and stabilizers (2-hydroxybenzophenone and tinuvin 770) composites were prepared by intercalation in solution method. The films of the composites were exposed to UV irradiation. The photodegradation products were monitored by FTIR (Fourier Transform Infrared Spectroscopy) and SEC (Size Exclusion Chromatography) method. The PEO pure showed higher degradation rate coefficients, kd , compared to the others samples. The system that showed the lowest value for the degradation rate coefficients (kd = 1.9×10–6 mol g –1 h –1) was the PEO/SWy-1 5% composite with 0.25% of tinuvin 770. In this case, the stabilization of the PEO matrix can be attributed to clay associated with tinuvin 770. The clay scatters and absorbs UV irradiation and tinuvin acts as a stabilizer of the HALS (hindered amine light stabilizers) kind.

O comportamento fotofísico do corante pseudoisocianina (PIC) foi estudado em solução macromolecular (alginato de sódio) e hidrotrópica (toluenossulfonato e estirenossulfonato de sódio). A localização do corante nestes meios modifica as propriedades espectroscópicas e os tempos de vida dos estados excitados. Os efeitos são atribuídos à interação do corante com as macromoléculas ou sua localização nos agregados hidrotrópicos, que induzem a formação de agregados J ou constringem suas movimentações internas reduzindo a velocidade da conversão interna. Os tempos de vida do estado triplete do corante em alginato foram de 20-30 ns em soluções recém preparadas, enquanto que, deixando a solução repousar por algumas horas o decaimento vira biexponencial com a formação de uma nova espécie com tempo de vida ao redor de 150 ns. Esta última é atribuída às moléculas do corante localizadas no ambiente do alginato.

The photophysical behaviour of the dye pseudoisocyanine (PIC) was studied in macromolecular (sodium alginate) and hydrotropic (sodium toluenesulphonate and sodium styrenesulphonate) solutions. It was found that the placement of the dye in these media affected the spectroscopic properties and the lifetimes of its excited states. The effects are traced down to the interactions of the dye molecules with the macromolecules or their placement in the hydrotropic aggregates, inducing the formation of J-aggregates of the dye or constraining its internal movements reducing the rate of internal conversion. The lifetimes of the triplet state of the dye in alginate were of the order of 20-30 ns in freshly prepared solutions, whereas when leaving the solution to rest for some hours the decay became biexponential with the growing of a species with lifetime around 150 ns. The latter is assigned to dye molecules placed in the alginate network.

The organoclay/poly(methyl methacrylate) (PMMA) nanocomposites were prepared by in situ photopolymerization method using two solvents, ethanol and acetonitrile. The influences of organoclay loading, solvent nature and length of attached surfactant (C8 or C16) on thermal and mechanical properties were studied by thermogravimetric analysis and dynamic mechanical analysis. Alkylammonium surfactants with C8 and C16 chain lengths were evaluated as clay modifiers. All the nanocomposites prepared in acetonitrile exhibited improvement in their thermal stability, mainly due to the interaction between the clay and the polymer which is maximized by the exfoliated clay structure. In the case of PMMA and nanocomposites synthesized in ethanol, the thermal stability of polymer and nanocomposites remained practically the same once the clay structure is predominantly of the intercalated type. In comparison with pure PMMA, glass transition temperature and storage modulus of polymer are notably increased by the presence of clay. It was found that the chain length of surfactant attached to the SWy-1 clay affects the Tg values. Glass transition temperatures of nanocomposites SWy-1-C16/PMMA were significantly higher than the values obtained for nanocomposites SWy-1-C8/PMMA. This can be attributed to the modifying agent C16, which has a greater hydrophobic chain length. The organic tail can provide a better dispersion of the MMA monomer in the organoclay, resulting in a nanocomposite with predominant exfoliated structure. Another significant factor to be considered was the effect of solvent used in the nanocomposite preparation. Considering nanocomposites with the same chain length (C8 or C16), Tg values obtained for nanocomposites prepared with ethanol is higher than those observed for those prepared in acetonitrile. This was attributed to the influence of the average molecular weight; once the nanocomposites prepared in ethanol exhibited higher polymeric chains.

O objetivo desta pesquisa foi determinar o rendimento de frutos de plantas matrizes de morangueiro (Fragaria x ananassa) após a produção de pontas de estolões. Plantas matrizes micropropagadas foram plantadas em 01 de outubro de 2008, em sistema de cultivo fora do solo. Pontas de estolões com pelo menos um primórdio radicular visível foram colhidas em 43, 66 e 87 dias após o plantio, enraizadas e plantadas como plantas matrizes multiplicadas para produção de mudas com torrão. Os tratamentos consistiram de plantas matrizes das cultivares INIA Arazá, INIA Guenoa e INIA Yvapitá, micropropagadas (T1) plantadas em 01 de outubro de 2008, plantas matrizes multiplicadas plantadas em 28 de novembro de 2008 (T2), 21 de dezembro de 2008 (T3) e 10 de janeiro de 2009 (T4). Em 22 de maio de 2009, as plantas matrizes micropropagadas e multiplicadas foram desfolhadas e plantas oriundas de mudas em bandejas das mesmas cultivares foram plantadas como testemunhas. A produção precoce e o número de frutos foram maiores nas plantas matrizes, porém o peso fresco de frutos foi maior nas plantas testemunhas. A produção total e o número de frutos foram maiores nas plantas matrizes das cultivares INIA Arazá e INIA Guenoa. Concluiu-se que, em sistema de cultivo fora do solo, após a produção de pontas de estolões, plantas matrizes de morango podem chegar inicialmente a uma maior produção de frutos e produção total de frutos frescos do que os transplantes com torrão. Portanto, elas não devem ser eliminadas após a produção de pontas de estolões.

The main objective of this research was to determine fruit yield of strawberry (Fragaria x ananassa) stock plants in a cropping system after producing runner tips and plug plants. Micropropagated stock plants were planted in a soilless growing system. Runner tips bearing at least one visible root nodule were harvested at 43, 66 and 87 days after planting, rooted and planted as multiplied stock plants for producing plug plants. Treatments consisted of micropropagated stock plants of cultivars INIA Arazá, INIA Guenoa and INIA Yvapitá, planted on October 1st, 2008 (T1); multiplied stock plants planted on November 28th (T2) and on December 21st, 2008 (T3), and on January, 10th, 2009 (T4). On May 22nd, 2009, stock plants were defoliated and plug plants of the same cultivars were planted as control for fruit production. Early fruit yield and number of fruits were higher on stock plants, but fresh fruit yield was higher on control plants. Total fruit yield and number were higher on stock plants of 'INIA Arazá' and 'INIA Guenoa'. We concluded that strawberry stock plants reach higher early and total fresh fruit yield than plug transplants in the second cropping year after producing runner tips in a soilless growing system. Therefore, plants should not be discarded after the production of runner tips.

Com a disseminação da Tecnologia de Informação e Comunicação no ambiente educacional, aliada à proliferação de ferramentas de autoria, a quantidade de material educacional digital sendo produzido aumentou significativamente. Tal situação acarretou a necessidade de ampliar o escopo dos repositórios digitais, com o propósito de incluir, nesses ambientes, conteúdos educacionais digitais produzidos segundo a estratégia de Objetos de Aprendizagem (OA), com vistas a favorecer a disponibilização e a reusabilidade desses conteúdos. Com esse novo escopo, esse tipo de repositório passou a ser conhecido como Repositórios de Objetos de Aprendizagem (ROA). A integração dos ROA com Ambientes Virtuais de Aprendizagem (AVA) tem o objetivo de facilitar o uso dos OA por parte dos professores, uma vez que o ambiente no qual os professores atuam mais frequentemente é o AVA. Este artigo apresenta uma estratégia para implementar a integração de ROA com AVA, exemplificando com uma implementação pautada pela estratégia proposta e que levou à integração de um ROA baseado no padrão Learning Object Metadata (LOM) com o AVA Modular Object-Oriented Dynamic Learning Environment (MOODLE).

Information and Communication Technology has been spread out through educational scenery as well as authoring tools proliferation, the amount of digital educational material being produced has meaningfully increased. This situation led to the necessity of expanding the scope of digital repositories aimed at including in these environments digital educational contents produced according to the strategy of Learning Objects (LO) in order to foster the availability and reusability from these contents. Within this new scope this type of repository has been known as Learning Object Repositories (LOR). The integration of crowns with Learning Management Systems (LMS) has as goal to facilitate the use of LO by teachers, since the environment in which teachers work more frequently is the LMS. This article presents a strategy to initiate the integration between LOR and AVA illustrating with an implementation strategy guided by the proposal and which led to the integration of an LOR based on the standard LOM with the LMS MOODLE.

O objetivo do trabalho foi determinar o efeito da frigoconservação das pontas de estolões na produção de plug plants e frutas de morangueiro. O experimento foi realizado em Santa Maria, RS, com mudas das cultivares 'Camarosa', 'Diamante' e 'Arazá', produzidas a partir de pontas de estolões submetidas ao armazenamento refrigerado por 0; 7; 14; 21; 28; e 35 dias na temperatura de 0,5±0,3°C e umidade relativa de 95±1%. Após a frigoconservação, as pontas de estolões foram enraizadas para produção de mudas, as quais foram plantadas no solo para produção de frutas. A taxa de sobrevivência e o número de folhas das mudas foram avaliados após o período de enraizamento. O número de frutas e de estolões emitidos e a produção de frutas foram avaliados durante os meses de junho a novembro de 2010. Concluiu-se que a frigoconservação das pontas de estolões para posterior enraizamento e produção de plug plants não afeta o crescimento e a taxa de sobrevivência das mudas. A produção de frutas das plantas oriundas dessas mudas diminui com o aumento do período de frigoconservação, enquanto a emissão de estolões aumenta linearmente, com diferenças entre as cultivares.

The objective of this research was to determine the effects of cold storage of strawberry runner tips used for production of plug plants and fruit yield in the field. The experiment was conducted in Santa Maria, RS, using plug plants rooted after 0; 7; 14; 21; 28 and 35 days of cold storage of runner tips at 0,5±0,3°C temperature and 95±1% air humidity. After the cold storage period, runner tips were rooted for plug plant production and planted in the field for fruit production. The survival rate and number of leaves of plug plants were recorded after rooting. Fruit and stolon number and fruit yield were determined from June to December 2010. It was concluded that the cold storage of runner tips for further rooting and plug plant production did not affect growth and survival of plug plants. Fruit yield of plants originated from such plug plants is reduced when the cold storage period is increased while emission of stolons is linearly enhanced, but these effects are cultivar dependent.

Polietilenoglicol (PEG) foi fotooxidado usando o sistema foto-Fenton e comparando com a reação no escuro. Os produtos foram analisados por GPC e HPLC. As amostras tratadas na ausência de luz necessitaram 490 min para que a <img src="/img/revistas/jbchs/v22n3/a18Mlinha.jpg" align=absmiddle>w decrescesse em 50%, enquanto que sob irradiação UV essa mesma proporção foi obtida em 10 min. O decaimento exponencial de <img src="/img/revistas/jbchs/v22n3/a18Mlinha.jpg" align=absmiddle>w com um concomitante aumento na polidispersividade e o número de quebras de cadeia caracteriza um mecanismo de quebra de cadeia aleatório. Os produtos da degradação de PEG em ambos os casos mostram a presença de produtos de massa molecular menor, incluindo etilenoglicóis menores e o ácido fórmico. O mecanismo da fotodegradação corresponde a processos consecutivos, onde etilenoglicóis de maior massa molar geram outros de menor massa, envolvendo quebras sucessivas das cadeias do polímero. O estudo demonstra que o processo de foto-Fenton com irradiação UV é um bom método para a decomposição de PEG.

Polyethyleneglycol (PEG) was photooxidized in a photo-Fenton system and results compared with the dark reaction. The products were analysed using GPC and HPLC. In the absence of light, PEG samples needed 490 min to reduce their <img src="/img/revistas/jbchs/v22n3/a18Mlinha.jpg" align=absmiddle>w by 50%, whereas under UV irradiation, only 10 min were necessary. The exponential decay of <img src="/img/revistas/jbchs/v22n3/a18Mlinha.jpg" align=absmiddle>w with a concomitant increase in polydispersity and number of average chain scission, characterized a random chain scission mechanism. The degradation products of PEG in both systems showed the presence of lower molecular weight products, including smaller ethyleneglycols and formic acid. The mechanism involves consecutive processes, were the larger ethyleneglycols give rise, successively, to smaller ones. This suggests that the mechanism involves successive scissions of the polymer chain. Irradiated samples decomposed faster than those kept in the dark This study proves that the foto-Fenton method associated with UV-light is a good reactant for PEG photodegradation.

Foi estudada a degradação fotooxidativa de QTX (cloreto de 2-hidroxi-3-(3,4-dimetil-9-oxo-9H-tioxanton-2-iloxi)-N,N,N-trimetil-1-propano) em solução aquosa. Os produtos resultantes foram caracterizados por HPLC/ESI-MS e a fotodegradação do corante foi acompanhada por espectroscopia de absorção. O corante apresenta duas bandas em 273 e 402 nm, que decrescem durante a irradiação, enquanto que aparece uma banda na região de 310-350 nm, típica do QTX oxidado. Novos picos devidos aos fotoprodutos da degradação de QTX foram observados por cromatografia e identificados por espectrometria de massa. Os picos em m/z 388, 420 e 270 correspondem a fotoprodutos, e o de m/z 372 é atribuído ao QTX. O pico de m/z 388 corresponde à formação de um grupo sulfóxido e o de m/z 420 sugere a formação de uma sulfona com uma hidroxila no grupo metila. O pico de m/z 270 sugere que o oxigênio reage com QTX abstraindo um hidrogênio do carbono ligado à hidroxila, simultaneamente à eliminação de um grupo amino.

The photooxidative degradation of QTX (2-hydroxy-3-(3,4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-N,N,N-trimethyl-1-propanium chloride) has been investigated and photoproducts from QTX degradation in aqueous solution were characterized using HPLC/ESI-MS. The photooxidation of the dye was monitored by electronic absorption spectroscopy. The spectrum of the dye shows bands at 273 and 402 nm. During irradiation, the intensity of these bands decreases together with the appearance of a band at 310-340 nm, typical of oxidized QTX. The chromatograms show the presence of new peaks due to photoproducts of QTX degradation that were identified by mass spectroscopy. The peaks at m/z 388, 420 and 270 were attributed to photoproducts, whereas the peak at m/z 372 is due to QTX. The peak at m/z 388 corresponds to the formation of a sulfoxide group and that at m/z 420 suggested the formation of a sulfone with a hydroxyl on the methyl group. The peak at m/z 270 suggests that oxygen reacts with QTX abstracting a hydrogen atom from the carbon bonded the hydroxyl, together with the release of the amino group.

O presente artigo trata das novas definições sobre comunidades de quilombo, elaboradas a partir da necessidade de reconhecimento oficial destas para que lhes seja assegurado o direito constitucional de propriedade sobre suas terras. Discute-se aqui o abandono de uma visão cristalizada pela historiografia clássica baseada no isolamento dos quilombos, bem como de sua formação única por meio das fugas, em prol de um conceito ampliado que alça o território e a identidade - especialmente ligados à resistência - à condição de elementos fundamentais na determinação destes agrupamentos sociais denominados remanescentes de quilombo.

The present article deals with new definitions of maroons' communities elaborated from the necessity to obtain official recognition which could ensure them the constitutional right of property over their lands . It rejects a classic historiography view which sustains the idea of maroons' isolation, as well as their unique formation by means of escaping, in favor of an enlarged concept that elevates territory and identity - especially linked to resistance - to the condition of crucial elements in determining these social groupings maroons' remainders.