Fluorescence quantum efficiency of CdSe/CdS magic-sized quantum dots functionalized with carboxyl or hydroxyl groups

AbstractThe present letter reports the thermo-optical properties of functionalized CdSe/CdS magic-sized quantum dots (MSQDs) (sizes 1.9–2.3nm) with carboxyl (R–COOH) or hydroxyl (R–OH) groups in aqueous solutions. Atomic force microscopy and infrared transmittance measurements were used to determine the size of the QDs and to highlight the functionalized groups. Absolute nonradiative quantum efficiency (φ) and radiative quantum efficiency (η) values were determined by applying two techniques: thermal lens (TL) and an alternative method that analyzes the ring patterns generated in a laser beam due to thermally induced self-phase-modulation effects known as the conical diffraction. Fluorescence measurements corroborate the TL results

Preparation of Polyaminopyridines Using a CuI/L-Proline-Catalyzed C-N Polycoupling Reaction

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Fluorescence Quantum Yields and Lifetimes of Aqueous Natural Dye Extracted from Tradescantia pallida purpurea at Different Hydrogen Potentials

In this work, we monitored the fluorescence quantum efficiency (η) and the fluorescence lifetime (τ) of natural dye extracts from the leaves of Tradescantia pallida purpurea. The natural dye was extracted from leaves in aqueous solutions as a function of the potential of hydrogen (pH). The η was determined from conical diffraction (CD) pattern measurements due to thermally-driven self-phase modulation. The fluorescence spectra and time-resolved fluorescence measurements corroborate the CD results, and the average η ≈ 0.28 and τ ≈ 3.1 ns values were obtained in the pH range 3.96–8.02. In addition, the extracted natural dye was tested as a possible colorimetric and/or fluorometric pH indicator in milk

Blunted dynamics of adenosine A2A receptors is associated with increased susceptibility to Candida albicans infection in the elderly

Opportunistic gut infections and chronic inflammation, in particular due to overgrowth of Candida albicans present in the gut microbiota, are increasingly reported in the elder population. In aged, adult and young mice, we now compared the relative intestinal over-colonization by ingested C. albicans and their translocation to other organs, focusing on the role of adenosine A2A receptors that are a main stop signal of inflammation. We report that elderly mice are more prone to over-colonization by C. albicans than adult and young mice. This fungal over-growth seems to be related with higher growth rate in intestinal lumen, independent of gut tissues invasion, but resulting in higher GI tract inflammation. We observed a particularly high colonization of the stomach, with increased rate of yeast-to-hypha transition in aged mice. We found a correlation between A2A receptor density and tissue damage due to yeast infection: comparing with young and adults, aged mice have a lower gut A2A receptor density and C. albicans infection failed to increase it. In conclusion, this study shows that aged mice have a lower ability to cope with inflammation due to C. albicans over-colonization, associated with an inability to adaptively adjust adenosine A2A receptors density

Mixed-Alkali Effect and Correlation to Glass Structure in Ionically Conductive P₂O₅-Al₂O₃-Na₂O-K₂O Glass System

In this study, the nature of the electrical transport and structural changes resulting from the systematic substitution of Al2O3 with K2O in 40P2O5-(25−x)Al2O3-35Na2O-xK2O, where x = 5.0, 7.5, 10.0, 12.5, and 15.0 mol% (PANxK), is investigated. The impact of the changes in glass structure and its correlation to electrical properties is presented. The mixed alkali effect (MAE) is observed due to the presence of two different alkali oxides, resulting in a non-monotonic trend in the studied glass properties. The infrared spectra show the shift and diminishing of the bands related to the P–O–P/P–O–Al bridges with increasing K2O content and changes in bands related to depolymerization of the glass network, which is confirmed by the trend of the Tg values. The minimum value of DC conductivity is obtained for glass with x = 12.5 mol%. With the overall increase in alkali content, the number of non-bridging oxygens increases, also affecting the conductivity values. Frequency-dependent conductivity spectra analyzed by Summerfield, Baranovskii-Cordes and Sidebottom scaling procedures revealed interesting features and signature of the MAE in the short-range dynamics of the potassium and sodium ions, both for individual glass composition and glass series as a whole. This study showed the impact of MAE and local glass structure on the electrical features and the prevailing of one effect over the other as a function of the glass composition. MAE dominates in a wider range, but with the significant increase in alkali content, MAE is consequently overpowered

Splenic architecture disruption and parasite-induced splenocyte activation and anergy in Plasmodium falciparum-infected Saimiri sciureus monkeys

This study was supported by funds from the PDTIS Program (Fiocruz), PRONEX-Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), DECIT-Ministry of Health and and Fundação de Apoio à Pesquisa do Estado do Rio de Janeiro (Faperj).Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Pesquisa em Malária. Rio de Janeiro, RJ, Brazil / Universidade Federal do Pará. Laboratório de Imunobiologia. Belém, PA, Brazil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Patologia. Rio de Janeiro, RJ, Brazil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Pesquisa em Malária, Rio de Janeiro, RJ, Brazil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Pesquisa em Malária. Rio de Janeiro, RJ, Brazil.Universidade Federal do Pará. Laboratório de Tecnologia Biomolecular. Belém, PA, Brazil.Universidade Federal do Pará. Laboratório de Polimorfismo de DNA. Belém, PA, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Centro Nacional de Primatas. Ananindeua, PA, Brasil.Instituto Carlos Chagas de Biologia Molecular. Curitiba, PR, Brazil.Fundação Oswaldo Cruz. Serviço de Criação de Primatas Não-Humanos. Rio de Janeiro, RJ, Brazil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Pesquisa em Malária. Rio de Janeiro, RJ, Brazil.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Laboratório de Pesquisa em Malária. Rio de Janeiro, RJ, Brazil.Background: The understanding of the mechanisms of immunity in malaria is crucial for the rational development of interventions such as vaccines. During blood stage infection, the spleen is considered to play critical roles in both immunity and immunopathology of Plasmodium falciparum infections. Methods: Saimiri sciureus monkeys were inoculated with blood stages of P. falciparum (FUP strain) and spleens removed during acute disease (days 7 and 13 of infection) and during convalescence (15 days after start of chloroquine treatment). Cytokine (IFNγ, TNFα, IL2, IL6, IL10, and IL12) responses of splenocytes stimulated with P. falciparum-parasitized red blood cells were assessed by real-time PCR using specific Saimiri primers, and histological changes were evaluated using haematoxylin-eosin and Giemsa-stained slides. Results: Early during infection (day 7, 1-2% parasitaemia), spleens showed disruption of germinal centre architecture with heavy B-cell activation (centroblasts), and splenocytes showed increased expression of IFNγ, IL6 and IL12 upon in vitro stimuli by P. falciparum-parasitized red blood cells (pRBC). Conversely, 15 days after treatment of blood stage infection with chloroquine, splenocytes showed spontaneous in vitro expression of TNFα, IL2, IL6, IL10, and IL12, but not IFNγ, and stimulation with P. falciparum pRBC blocked the expression of all these cytokines. During the acute phase of infection, splenic disarray with disorganized germinal centres was observed. During convalescence, spleens of the chloroquine-treated animals showed white pulp hyperplasia with extensive lymphocyte activation and persistency of heavily haemozoin-laden macrophages throughout the red pulp. Conclusions: Inability to eliminate haemozoin is likely involved in the persistent lymphocyte activation and in the anergic responses of Saimiri splenocytes to P. falciparum pRBC, with important negative impact in immune responses and implications for the design of malaria vaccine

Avaliação da debulha mecânica em sementes de milho Evaluation of mechanical thrashing processing in corn seeds

No estado da Paraíba, as perdas de sementes e grãos de milho (Zea mays L.) provocadas principalmente pela colheita, debulha mecânica, beneficiamento e processos subseqüentes, são da ordem de 20%, acarretando prejuízos econômicos ao estado. Assim, estudaram-se as danificações decorrentes da debulha mecânica e da passagem das sementes de milho, variedades Cruzeta e Sertanejo, pelas diferentes etapas do beneficiamento. Para avaliar os danos provocados às sementes, utilizou-se uma debulhadora estacionária trabalhando a rotações de 520, 600 e 700 rpm, obtidas pela variação da aceleração do motor do trator ao qual a debulhadora se achava acoplada, como também das etapas promovidas pela UBS. Os danos foram avaliados visualmente e analisados em um delineamento estatístico inteiramente casualizado, com os tratamentos distribuídos em esquema fatorial. A variedade Cruzeta foi mais resistente aos impactos provocados pela debulha e pelo beneficiamento; o efeito do impacto na qualidade das sementes torna-se mais evidente com a elevação da velocidade do cilindro debulhador; a rotação de 600 rpm mostrou-se a mais indicada para a debulha do milho Cruzeta e Sertanejo.<br>In the State of Paraiba, the loss of seeds and grains of corn (Zea mays L.) caused, mainly by harvesting, mechanical thrashing and subsequent processes is about 20% resulting in economic loss to the state. In this context, the effect of mechanical damages during the thrashing and passage of corn seeds varieties -Cruzeta- and -Sertanejo- were studied, in the different stages of processing. To evaluate the damages caused to the seeds, a stationary thrasher was used working at 520, 600 and 700 rpm, obtained by the acceleration variation of the tractor to which the thrasher was attached. The damages were visually appraised and analysed in a completely randomized statistical design with the treatments distributed in a factorial scheme. -Cruzeta- variety was more resistant to the impacts caused by the thrashing and processing; the impacts on the seed quality became more evident with the elevation of speed of the thrashing cylinder; the 600 rpm rotation proved to be better for the thashing of Cruzeta and Sertanejo corn