The effect of substitution and isomeric imperfection on the photophysical behaviour of p-phenylenevinylene trimers

Spectroscopic and photophysical properties of two p-phenylenevinylene (PV) trimers, 2,5-substituted diheptyl-(p-phenylenevinylene) and di-[(2-ethylhexyl)oxy]-(p-phenylenevinylene), were studied using absorption spectroscopy, fluorescence and laser flash photolysis. The change from alkyl to alkyloxy groups red-shifts the absorption and fluorescence bands. The rate of internal conversion is independent of the substitution, whereas alkyloxy substitution increases the S1 [rightwards wave arrow] T1 intersystem crossing rate by an order of magnitude. The relevance for the behaviour of conjugated PPV polymers is discussed. For diheptyl-PV, a sample having ca. 3% of the cis-configuration was also studied. Comparison between the all-trans and the cis-contaminated samples revealed no significant differences in their photophysical properties.http://www.sciencedirect.com/science/article/B6TFN-4C0TKVG-4/1/bb1be7e4a272bb7910483cae927d04a

The effect of gamma-cyclodextrin addition in the self-assembly behavior of pyrene labeled poly(acrylic) acid with different chain sizes

The interaction between poly(acrylic acid) polymers (PAA) of low- (2000 g/mol) and high- (450,000 g/mol) molecular weight (Mw) hydrophobically modified with pyrene (PAAMePy) and beta- and gamma-cyclodextrins (beta-CD, gamma-CD) was investigated with fluorescent techniques. The interaction with beta-CD promotes little variation in the spectral and photophysical behavior of the polymer, whereas significant changes are observed upon addition of gamma-CD. The degree of inclusion (between the pyrene groups of the polymer and the cyclodextrins) is followed through the observation of the changes in the absorption, excitation (collected in the monomer and excimer emission regions) and emission (IE/IM ratio) spectra and from time-resolved data. Within the studied range of gamma-CD concentration, the fluorescence decays of the long chain (high Mw) PAAMePy polymers were found tri-exponential in the monomer and excimer emission regions in agreement with previous studies. In the case of the low Mw PAAMePy polymers, tri-exponential decays were observed at the monomer and excimer emission wavelengths. However, when a gamma-CD concentration of 0.01 and 0.03 M is reached for, respectively, the low- and high-labeled pyrene short chain (low Mw) polymers, the fluorescence decays in the excimer region become biexponential (two excimers) with no rising component, thus showing that all pyrene groups are encapsulated (and preassociated) into the gamma-CD cavity. In the case of the high Mw polymers, the addition of gamma-CD has been found to change the level of polymer interaction from pure intramolecular (water in the absence of cyclodextrin) to a coexistence of intra- with intermolecular interactions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1402-1415, 200

Photochemistry and photophysics of thienocarbazoles

Two methylated thienocarbazoles and two of their synthetic nitro-precursors have been examined by absorption, luminescence, laser flash photolysis and photoacoustic techniques. Their spectroscopic and photophysical characterization involves fluorescence spectra, fluorescence quantum yields and lifetimes, and phosphorescence spectra and phosphorescence lifetimes for all the compounds. Triplet-singlet difference absorption spectra, triplet molar absorption coefficients, triplet lifetimes, intersystem crossing S-1 similar tosimilar to--> T-1 and singlet molecular oxygen yields were obtained for the thienocarbazoles. In the case of the thienocarbazoles it was found that the lowest-lying singlet and triplet excited states, S, and T-1, are of pi,pi* origin, whereas for their precursors S-1 is n,pi*, and T-1 is pi,pi*. In both thienocarbazoles it appears that the thianaphthene ring dictates the S, T, yield, albeit there is less predominance of that ring in the triplet state of the linear thienocarbazole, which leads to a decrease in the observed Phi(T) value.info:eu-repo/semantics/publishedVersio

Simple discrimination and conceptual behavior based on location : influence of different types of training

Comportamento conceitual envolve o estabelecimento de classes de estímulos com discriminação interclasses e generalização intraclasse. Esta pesquisa verificou a relação entre o tipo de modificação dos estímulos nos treinos discriminativos e a aquisição de discriminações e de comportamento conceitual de posição. Quinze crianças de 4- 6 anos realizaram tarefas de discriminação simples de posição. Três condições experimentais com treino discriminativo diferente (modificação gradual – MG, múltiplos exemplares – ME e sem modificação - SM dos estímulos utilizados no treino) foram realizadas com todas as crianças. Os participantes deveriam selecionar, em cada condição, o estímulo cujo elemento relacional se localizava dentro, em cima ou à esquerda do elemento de referência. Os treinos foram intercalados com um teste de comportamento conceitual que apresentava estímulos treinados e novos que se diferenciavam apenas com relação à dimensão crítica. Resultados do treino mostraram altos escores nas três condições e menos erros com o Treino MG. Nos testes de comportamento conceitual, desempenhos acima do acaso foram obtidos apenas após o Treino SM. A modificação gradual de estímulos e a utilização de múltiplos exemplares reduziram os erros nos treinos e facilitaram o estabelecimento de discriminações entre estímulos treinados. O treino discriminativo SM com diversas tentativas com os pares de estímulos finais, que diferem apenas na dimensão relevante, produziu comportamento conceitual. Combinar os procedimentos parece, portanto, necessário para acelerar a aquisição das discriminações, prevenir subprodutos dos erros e para gerar controle de estímulos pelas dimensões relevantes _______________________________________________________________________________ ABSTRACTConceptual behavior encompasses formation of stimulus classes with discrimination between classes and generalization within class. This research verified the relationship between the type of stimulus modification during discrimination training and the acquisition of position discrimination and related conceptual behavior. Fifteen 4-6 year-old children were exposed to simple position discrimination tasks. Three experimental conditions (gradual change – MG; multiple exemplars – ME; and no change - SM, of S+ and S- stimuli) were programmed for all participants. Participants should select in one condition the stimulus which had a relational element placed inside, over or on the left of a reference element. Training of a different position was interspersed with tests of conceptual behavior which presented for selection trained and new stimuli which differed only in respect to the critical dimension. In general, the percentage of correct responses during the training was high for all conditions with fewer errors in MG. During conceptual behavior tests, however, percentages of correct responses were above chance level only after the SM discriminative training. Procedures MG and ME reduced errors and facilitated the establishment of discriminations between training stimuli which differed in more than one dimension. SM procedure, with several trials presenting stimuli with critical difference, produced conceptual behavior. Results suggest that the combination of varying stimulus along the training and repeated trials with stimuli differing only in the relevant dimension are necessary to speed the acquisition of discriminations, to prevent by-products of errors and to produce stimulus control by critical dimension

José Antunes Ribeiro (Alburitel, 1942- )

UID/HIS/04666/2013 UID/HIS/04666/2019publishersversionpublishe

Uma Aventura (Lisboa, 1984- )

UID/HIS/04666/2013 UID/HIS/04666/2019publishersversionpublishe

Parâmetros físicos e fisiológicos relacionados com a tolerância ao calor em ovinos no Brasil

Tese (doutorado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, Programa de Pós-graduação em Ciências Animais, 2016.A adaptabilidade aos ambientes tropicais, tolerância ao calor, bem como a capacidade de prever os efeitos ambientais nos animais são fatores importantes para a ovinocultura. Este trabalho teve como objetivos avaliar a tolerância ao calor de 26 ovinos da raça Santa Inês (SI) e Morada Nova (MN) no Distrito Federal e se os índices ambientais e os coeficientes de tolerância ao calor existentes são adequados para avaliar o estresse pelo calor em nessas raças, utilizando parâmetros climáticos, sanguíneos, físicos, fisiológicos, termográficos e coeficientes de adaptabilidade. Bem como e definir os parâmetros sanguíneos e fisiológicos para os ovinos no Brasil utilizando 5081 observações de experimentos anteriores realizados com ovinos de diferentes regiões (Nordeste, Centro-oeste e Sul) com dados de período do dia, sexo, raça, idade, características fisiológicas, hematológicas e variáveis climáticas. As análises estatística incluíram as análises de média variância, correlações, broken lines e componentes principais. Foi observado que a raça influenciou significativamente (p<0,001) características fisiológicas e físicas de pele, pêlo, medidas biométricas e os coeficientes de tolerância ao calor de Ibéria e Benezra. Apesar de ambas as raças poderem ser consideradas adaptadas às condições ambientais da região, considerando coeficientes de tolerância ao calor e características físicas, a raça MN pode ser considerada melhor adaptada às condições locais. A correlação positiva encontrada entre as temperaturas termográficas e os parâmetros fisiológicos, indicou que esta técnica pode ser utilizada para avaliar o conforto térmico animal, tendo como vantagem a não manipulação do animal, o que favorece o bem-estar do animal. Os índices de Ibéria e Benezra foram os coeficientes de tolerância que melhor se correlacionaram com as características avaliadas. Foi observada alta correlação entre os índices ambientais e as temperaturas retais e superficiais da pele, o que indica que esses índices podem ser utilizados para avaliação de conforto térmico para ovinos destas raças. Porém, os valores indicativos de desconforto térmico são diferentes da classificação existente. A frequência respiratória foi o parâmetro que mais divergiu em relação aos padrões de normalidade, com valores acima dos limites para a espécie, sendo superior nos ovinos de raças comerciais lanadas. No hemograma também foram observadas divergências entre os resultados e os valores citados na literatura. Assim, considerando que parâmetros fisiológicos e hematológicos são indicadores do estado patológico ou fisiológico do animal, para uma correta interpretação dos resultados é recomendada a utilização de valores de referência baseados em animais com características raciais semelhantes e submetidos às condições ambientais similares.Adaptability to tropical environments, heat tolerance and the ability to predict the effects of the environment on animals are important factors in sheep production. The aim of this study was to evaluate heat tolerance of 26 Santa Ines (SI) and Morada Nova (MN) sheep in the Federal District of Brazil and to analyze whether existing indices are suitable for evaluating heat stress in these breeds using thermography, climatic, blood, physical, physiological parameters and heat tolerance indices. As well as to determine blood and physiological parameters of sheep in Brazil using 5081 observations from previous experiments with animals from different regions (Northeast, Midwest and South) with time of day, gender, breed, age, physiological characteristics, hematological and climatic variables. Statistical analysis included analysis of variance, means, correlation, broken lines and principal components. Breed significantly influenced (p< 0.001) physiological and physical characteristics of skin, hair, biometric measurements and Iberia and Benezra heat tolerance indices. Although both breeds can be considered adapted to the environmental conditions of the region, considering heat tolerance indices and physical characteristics MN breed can be considered more adapted to the region. The positive correlation found between the thermograph temperatures and physiological parameters indicates that this technique can be used to evaluate thermal comfort, having the advantage that animals do not have to be handled, which favors animal welfare. The indices of Iberia and Benezra were the tolerance indices based on animal measures that best correlated with the assessed parameters. High correlation between environmental indices and rectal and skin surface temperatures was observed, which indicates that these indices can be used for these sheep breeds. However, some indicative values of thermal discomfort are different from the existing classification. Respiratory rate was the parameter that most differed in relation to the published normal range, with values above the limits for the species, being higher in commercial wool sheep. For blood count, differences were also observed between the results and the values reported in the literature. Considering that physiological and hematological parameters are indicators of the pathological or physiological state of the animal, for a correct interpretation of the results the use of reference values based on animals with similar breed characteristics and subjected to similar environmental conditions is recommended

Editorial Caminho (Lisboa, 1975- )

UID/HIS/04666/2013 UID/HIS/04666/2019publishersversionpublishe

Vega (Lisboa, 1976- )

UID/HIS/04666/2013 UID/HIS/04666/2019Entrada da enciclopédia on line Portal Editores y Editoriales Iberoamericanos (siglos XIX-XXI), abreviadamente EDI-RED.publishersversionpublishe

Cadernos Peninsulares-Peninsulares (Lisboa, 1970-2016?)

UID/HIS/04666/2013 UID/HIS/04666/2019publishersversionpublishe