303 research outputs found

    Poly(2-propylacrylic acid)/poly(lactic-co-glycolic acid) blend microparticles as a targeted antigen delivery system to direct either CD4+ or CD8+ T cell activation.

    Get PDF
    Poly(lactic-co-glycolic acid) (PLGA) based microparticles (MPs) are widely investigated for their ability to load a range of molecules with high efficiency, including antigenic proteins, and release them in a controlled manner. Micron-sized PLGA MPs are readily phagocytosed by antigen presenting cells, and localized to endosomes. Due to low pH and digestive enzymes, encapsulated protein cargo is largely degraded and processed in endosomes for MHC-II loading and presentation to CD4+ T cells, with very little antigen delivered into the cytosol, limiting MHC-I antigenic loading and presentation to CD8+ T cells. In this work, PLGA was blended with poly(2-propylacrylic acid) (PPAA), a membrane destabilizing polymer, in order to incorporate an endosomal escape strategy into PLGA MPs as an easily fabricated platform with diverse loading capabilities, as a means to enable antigen presentation to CD8+ T cells. Ovalbumin (OVA)-loaded MPs were fabricated using a water-in-oil double emulsion with a 0% (PLGA only), 3 and 10% PPAA composition. MPs were subsequently determined to have an average diameter of 1 µm, with high loading and a release profile characteristic of PLGA. Bone marrow derived dendritic cells (DCs) were then incubated with MPs in order to evaluate localization, processing, and presentation of ovalbumin. Endosomal escape of OVA was observed only in DC groups treated with PPAA/PLGA blends, which promoted high levels of activation of CD8+ OVA-specific OT-I T cells, compared to DCs treated with OVA-loaded PLGA MPs which were unable activate CD8+ T cells. In contrast, DCs treated with OVA-loaded PLGA MPs promoted OVA-specific OT-II CD4+ T cell activation, whereas PPAA incorporation into the MP blend did not permit CD4+ T cell activation. These studies demonstrate PLGA MP blends containing PPAA are able to provide an endosomal escape strategy for encapsulated protein antigen, enabling the targeted delivery of antigen for tunable presentation and activation of either CD4+ or CD8+ T cells

    La paratextualitat en la traducció mediambiental de divulgació: els jocs de paraules i la intertextualitat

    Get PDF
    Environmental discourse appears in the USA in the mid-20th century, and comes to us through translation, especially in the form of popularising literature. This article focuses on the analysis of five ecologist handbooks and the respective translations into Catalan and Spanish. We analyse their paratextuality, as an example of cultural aspects found in this kind of text, and more specifically intertextual and linguistic puns found in the original texts. In this respect, we also propose a classification of puns and describe the translation strategies within these translated versions. Finally we analyse sociolinguistic issues related to each translation language and the relevance of these translated puns in the texts as a whole

    Combustion Modeling Approach for the Optimization of a Temperature Controlled Reactivity Compression Ignition Engine Fueled with Iso-Octane

    Get PDF
    In this study, an innovative Low Temperature Combustion (LTC) system named Temperature Controlled Reactivity Compression Ignition (TCRCI) is presented, and a numerical optimization of the hardware and the operating parameters is proposed. The studied combustion system aims to reduce the complexity of the Reaction Controlled Compression Ignition engine (RCCI), replacing the direct injection of high reactivity fuel with a heated injection of low reactivity fuel. The combustion system at the actual state of development is presented, and its characteristics are discussed. Hence, it is clear that the performances are highly limited by the actual diesel-derived hardware, and a dedicated model must be designed to progress in the development of this technology. A Computational Fluid Dynamics (CFD) model suitable for the simulation of this type of combustion is proposed, and it is validated with the available experimental operating conditions. The Particle Swarm Optimization (PSO) algorithm was integrated with the Computational Fluid Dynamic (CFD) software to optimize the engine combustion system by means of computational simulation. The operating condition considered has a relatively high load with a fixed fuel mass and compression ratio. The parameters to optimize are the piston bowl geometry, injection parameters and the boosting pressure. The achieved system configuration is characterized by a wider piston bowl and injection angle, and it is able to increase the net efficiency of 3% and to significantly reduce CO emissions from 0.407 to 0.136 mg

    Environmental and biological controls on water and energy exchange in Florida scrub oak and pine flatwoods ecosystems

    Get PDF
    Scrub oak and pine flatwoods are two contrasting ecosystems common to the humid subtropical climate of Florida. Scrub oak forests are short in stature (<2 m) and occur on well-drained sandy soils, and pine flatwoods are much taller and occur in areas with poorly drained soils. Eddy covariance measurements were made from January 2001 to February 2003 over a scrub oak forest and from January 2002 to February 2003 over an adjacent pine flatwoods located on in central Florida, USA, and exposed to similar atmospheric conditions to evaluate how the dynamics of latent heat (lambda E) and sensible heat (H) exchanges are affected by environmental and biological variables. Annual evapotranspiration (Et) for the scrub oak was 737 and 713 mm in 2001 and 2002, respectively. Et was comparatively higher, 812 mm, in 2002 at the pine flatwoods due to higher soil moisture and leaf area. In both ecosystems, springtime increases in lambda E coincided with increasing leaf area and evaporative demand. However, H was the main energy-dissipating component in the spring due to the seasonal decrease in soil water content in the upper soil profile. In the spring, mean weekly Bowen ratio (beta, i.e. H/lambda E) values reached 1.6 and 1.2 in the scrub oak and pine flatwoods, respectively. With the onset of the summertime rainy season, lambda E became the dominant energy flux and beta fells to < 0.4. In both ecosystems, beta was strongly controlled by the interaction between leaf area and soil moisture. The lowest values of the decoupling coefficient (Omega, 0.2 and 0.25 scrub oak and pine flatwoods, respectively) also occurred during the dry springtime period indicating that surface conductance (g(s)) was the mechanism controlling energy partitioning causing high beta in both ecosystems. Et increases in the spring, when water in the upper soil profile was scarce and strongly retained by soil particles, indicated that plants in both ecosystems obtained water from deeper sources. The results from this research elucidate how energy partitioning differs and is regulated in contrasting ecosystems within the Florida landscape, which is important for refining regional hydrological and climate models

    Environmental and biological controls on water and energy exchange in Florida scrub oak and pine flatwoods ecosystems

    Get PDF
    Scrub oak and pine flatwoods are two contrasting ecosystems common to the humid subtropical climate of Florida. Scrub oak forests are short in stature (\u3c2 \u3em) and occur on well-drained sandy soils, and pine flatwoods are much taller and occur in areas with poorly drained soils. Eddy covariance measurements were made from January 2001 to February 2003 over a scrub oak forest and from January 2002 to February 2003 over an adjacent pine flatwoods located on in central Florida, USA, and exposed to similar atmospheric conditions to evaluate how the dynamics of latent heat (lambda E) and sensible heat (H) exchanges are affected by environmental and biological variables. Annual evapotranspiration (Et) for the scrub oak was 737 and 713 mm in 2001 and 2002, respectively. Et was comparatively higher, 812 mm, in 2002 at the pine flatwoods due to higher soil moisture and leaf area. In both ecosystems, springtime increases in lambda E coincided with increasing leaf area and evaporative demand. However, H was the main energy-dissipating component in the spring due to the seasonal decrease in soil water content in the upper soil profile. In the spring, mean weekly Bowen ratio (beta, i.e. H/lambda E) values reached 1.6 and 1.2 in the scrub oak and pine flatwoods, respectively. With the onset of the summertime rainy season, lambda E became the dominant energy flux and beta fells to \u3c 0.4. In both ecosystems, beta was strongly controlled by the interaction between leaf area and soil moisture. The lowest values of the decoupling coefficient (Omega, 0.2 and 0.25 scrub oak and pine flatwoods, respectively) also occurred during the dry springtime period indicating that surface conductance (g(s)) was the mechanism controlling energy partitioning causing high beta in both ecosystems. Et increases in the spring, when water in the upper soil profile was scarce and strongly retained by soil particles, indicated that plants in both ecosystems obtained water from deeper sources. The results from this research elucidate how energy partitioning differs and is regulated in contrasting ecosystems within the Florida landscape, which is important for refining regional hydrological and climate models

    ESTUDIO DE LA INFLUENCIA DE LA ANISOTROPÍA UNIAXIAL EN LAS CURVAS DE MAGNETIZACIÓN DEL Co10Cu90

    Get PDF
    &nbsp;&nbsp;We studied the influence of uniaxial anisotropy on the magnetization curves of a Co10Cu90 alloy by means of a model that is developed taking into account correction terms for the partition function in the limit of large anisotropy and aligned grains. This result is a sum of terms where the first term is the Brillouin function of quantum paramagnetism. Fitting of our curves to the discussed model was compared with another model that considers the influence of the distribution of magnetic moments and we observe a good agreement. We show that the uniaxial anisotropy is enough to consider its effects on the system.&nbsp;&nbsp;Se estudió la influencia que tiene la anisotropía uniaxial en las curvas de magnetización de la aleación Co10Cu90 con ayuda de un modelo que toma en cuenta términos de corrección para la función de partición en el límite de alta anisotropía y granos alineados. El resultado es una suma de términos en los cuales el primero de ellos es la función de Brillouin del paramagnetismo cuántico. Se hace una comparación de nuestras curvas de magnetización ajustadas con otras, obtenidas en la literatura, en donde se considera la influencia de la distribución de momentos magnéticos y se observa una concordancia adecuada. Se llega a la conclusión de que la anisotropía uniaxial es lo suficientemente predominante como para considerar únicamente sus efectos sobre el sistema

    Estudio de la influencia de la anisotropía uniaxial en las curvas de magnetización del Co10Cu90

    Get PDF
    Se estudió la influencia que tiene la anisotropía uniaxial en las curvas de magnetización de la aleación Co10Cu90 con ayuda de un modelo que toma en cuenta términos de corrección para la función de partición en el límite de alta anisotropía y granos alineados. El resultado es una suma de términos en los cuales el primero de ellos es la función de Brillouin del paramagnetismo cuántico. Se hace una comparación de nuestras curvas de magnetización ajustadas con otras, obtenidas en la literatura, en donde se considera la influencia de la distribución de momentos magnéticos y se observa una concordancia adecuada. Se llega a la conclusión de que la anisotropía uniaxial es lo suficientemente predominante como para considerar únicamente sus efectos sobre el sistema

    Ecosystem carbon 7 dioxide fluxes after disturbance in forests of North America

    Get PDF
    Disturbances are important for renewal of North American forests. Here we summarize more than 180 site years of eddy covariance measurements of carbon dioxide flux made at forest chronosequences in North America. The disturbances included stand-replacing fire (Alaska, Arizona, Manitoba, and Saskatchewan) and harvest (British Columbia, Florida, New Brunswick, Oregon, Quebec, Saskatchewan, and Wisconsin) events, insect infestations (gypsy moth, forest tent caterpillar, and mountain pine beetle), Hurricane Wilma, and silvicultural thinning (Arizona, California, and New Brunswick). Net ecosystem production (NEP) showed a carbon loss from all ecosystems following a stand-replacing disturbance, becoming a carbon sink by 20 years for all ecosystems and by 10 years for most. Maximum carbon losses following disturbance (g C m−2y−1) ranged from 1270 in Florida to 200 in boreal ecosystems. Similarly, for forests less than 100 years old, maximum uptake (g C m−2y−1) was 1180 in Florida mangroves and 210 in boreal ecosystems. More temperate forests had intermediate fluxes. Boreal ecosystems were relatively time invariant after 20 years, whereas western ecosystems tended to increase in carbon gain over time. This was driven mostly by gross photosynthetic production (GPP) because total ecosystem respiration (ER) and heterotrophic respiration were relatively invariant with age. GPP/ER was as low as 0.2 immediately following stand-replacing disturbance reaching a constant value of 1.2 after 20 years. NEP following insect defoliations and silvicultural thinning showed lesser changes than stand-replacing events, with decreases in the year of disturbance followed by rapid recovery. NEP decreased in a mangrove ecosystem following Hurricane Wilma because of a decrease in GPP and an increase in ER
    corecore