Theoretical Study of Fluid Forces on a Centrifugal Impeller Rotating and Whirling in a Volute

Fluid forces on a rotating and whirling centrifugal impeller in a volute are analyzed with the assumption of a two-dimensional rotational, inviscid flow. For simplicity, the flow is assumed to be perfectly guided by the impeller vanes. The theory predicts the tangential and the radial force on the whirling impeller as functions of impeller geometry, volute spacing, and whirl ratio. A good qualitative agreement with experiment is found

Two-dimensional unsteady analysis of fluid forces on a whirling centrifugal impeller in a volute

Destabilizing fluid forces on a whirling centrifugal impeller rotating in a volute were observed. A quasisteady analysis neglecting shed vorticity or an unsteady analysis without a volute does not predict the existence of such destabilizing fluid forces on a whirling impeller. The effects of a volute and the shed vorticity are considered. We treat cases when an impeller with an infinite number of vanes rotates with a constant velocity omega and its center whirls with a constant eccentric radius epsilon and a constant whirling velocity psi. It is assumed that: (1) the number of the vanes is so large that the impeller can be treated as an actuator impeller in which the flow is perfectly guided; (2) flow is inviscid, incompressible and two dimensional; (3) the eccentricity epsilon is so small that unsteady components can be linearized; (4) vorticity is transported on a prescribed mean flow, the operating point is near design flow rate; and (5) the volute can be represented by a curved plate

Asociación de las subunidades de PI3-CINASA de clase IAA ICOS(CD278) y su importancia en la coestimulación

140 p.-48 fig.-2 AnexosICOS es una molécula coestimuladora expresada en linfocitos T activados; comparte con CD28 un motivo citoplasmico (YxxM), importante en la señalización celular por ser potencialmente capaz de asociar las subunidades reguladoras de PI3-cinasa. Puesto que hay una diversidad de subunidades catalíticas en las PI3-cinasas de clase IA (, , ), con importantes diferencias en su expresión y –posiblemente- en sus funciones, hemos analizado la asociación de las distintas subunidades de PI3-cinasa a ICOS. En este trabajo se analizaron por ensayos de “pull-down” aquellas proteínas de lisado de células SR.D10, linfocitos T CD4+ y linfoblastos capaces de unirse a péptidos de ICOS fosforilados en el residuo de tirosina (ICOSpTir) y a inmunoprecipitados de ICOS. Los péptidos ICOSpTir asocian las subunidades reguladoras de PI3-cinasa (p85, p85, p50-55) y las subunidades catalíticas (p110, p110 y p110). Por ensayos de “inmunoblot” se encontró una asociación preferencial de la subunidad catalítica p110 a péptidos ICOSpTir pero también a inmunoprecipitados de ICOS. Además, al inmunoprecipitar PI3-cinasa con anticuerpos frente a la subunidad reguladora se observó una unión preferencial de la subunidad p110 a la subunidad reguladora, explicando la asociación preferencial de esta subunidad a ICOS. Como se ha postulado una importancia funcional preferente de la subunidad catalítica p110 en la activación de linfocitos T, se han analizado las funciones de ambas subunidades p110 y p110 en la coestimulación por ICOS. Al estudiar la fosforilación de Akt y la producción de citocinas inducida por anti-CD3 y anti-ICOS en diferentes tipos celulares observamos una diferente sensibilidad de los residuos Ser473 y Tre308 de Akt al utilizar inhibidores dirigidos a diferentes subunidades catalíticas p110, confirmando la importancia de estas subunidades en la activación de Akt. Así, en células SR.D10 la activación temprana de Akt (Ser473), fue bloqueada parcialmente al inhibir las subunidades catalíticas p110 y p110 de PI3-cinasa con siARN o con inhibidores farmacológicos; en blastos de linfocitos T CD4+, la fosforilación en la Treonina 308 de Akt fue inhibida eficientemente por inhibidores de p110 (A66), p110 (IC87114), o de todas las isoformas (LY294002), mientras que la fosforilación en la Serina 473 fue inhibida parcialmente por el inhibidor de p110 (A66), y totalmente por el de p110, o por LY294002. Estos resultados confirman la importancia de estas subunidades en la activación de Akt. En cuanto a la secreción de citocinas encontramos que la producción de IL-4 e IL-10 es dependiente de la vía PI3-cinasa/Akt en células SR.D10, ya que el inhibidor general de PI3-cinasa (LY294002) y de las subunidades catalíticas p110 y p110 inhiben la secreción de estas citocinas En blastos no se observó un efecto significativo sobre la producción de IL-4 o IL-10, pero si sobre la producción de IFN- con concentraciones más bajas de los dos inhibidores de p110.La asociación preferente de las subunidades catalíticas p110 a las subunidades reguladoras de PI3-cinasa no es específica de la región citoplasmática de ICOS, también pudimos observarla asociada a un péptido de CD28 fosforilado en su motivo YxxM. Al analizar el papel de p110 en la coestimulación por CD28 encontramos que, a concentraciones de 1-0,1 M, el inhibidor de p110 (PIK-75) inhibía completamente la proliferación a tres días y la producción de citocinas como IL-2 o IFN-. Sin embargo, observamos que esta inhibición estaba acompañada por una fuerte pérdida de viabilidad en las células a partir de las 24 horas de cultivo. El uso de inhibidores y el silenciamiento de la subunidad catalítica p110 confirmaron la importancia de esta subunidad en la supervivencia de linfocitos T. Además, la muerte celular inducida por PIK-75 es dependiente de caspasas en linfocitos T CD4+ pero no en la línea celular SR.D10. También demostramos que la ligación de ICOS induce elongación celular y gránulos densos o puntos de actina polimerizada que se encuentran muy cerca de la superficie de contacto célulacristal; estos cambios morfológicos son dependientes de PI3-cinasa, en especial de la subunidad catalítica p110. Los cambios en el citoesqueleto de actina inducidos por ICOS son dependientes de Vav, de las GTPasas Rac-1 y Cdc42, y de la cinasa de la cadena ligera de miosina (MLCK), pero independientes de la vía de Akt o de ROCK. ICOS incrementa el agrupamiento de balsas lipídicas inducida por anticuerpo anti-CD3 en el sitio de contacto con el estímulo. Sin embargo, ICOS, es indetectable en las balsas de membrana, incluso empleando ligandos (CD3 o ICOS) capaces de inducir cambios claros en el citoesqueleto de actina. En conjunto, en este trabajo resaltamos la importancia de PI3-cinasa de clase IA en la coestimulación de ICOS; no solo confirmamos la importante función de la subunidad catalítica p110, sino que también atribuimos un papel dominante a la subunidad catalítica p110, que la convierte en una nueva diana potencial en la terapéutica inmunomoduladora. La investigación adicional de los modelos de ratón seguirá aportando pistas sobre los posibles beneficios y retos de una terapia dirigida a p110 de PI3-cinasa.Beca Predoctoral del programa “Junta para la Ampliación de Estudios” del C.S.I.C. correspondiente al año 2008.Peer reviewe

Application of Near Infrared Reflectance Spectroscopy (NIRS) to Forage Evaluation in Uruguay

Near infrared reflectance spectroscopy (NIRS) were used to assess the chemical composition of a wide range of forages. Nearly five hundred herbage samples covering a wide range of temperate pastures species and mixtures, previously analysed by conventional wet chemistry were scanned in reflectance with a NIRS 6500 (NIRSystems, Silver Spring, USA). The coefficients of determination in calibration (R2 ) and the errors in cross validation (SECV) were 0.98 (5.8), 0.94 (22.2), 0.97 (5.6), 0.94 (6.9) and 0.89 (19.7) for crude protein, in vitro organic matter digestibility, dry matter, ash and acid detergent fiber, in g kg –1 on a dry weight respectively. The high correlation between NIRS and chemical analysis found in this study showed the potential use of NIRS for prediction forage quality

ETP-46321, a dual p110α/δ class IA phosphoinositide 3-kinase inhibitor modulates T lymphocyte activation and collagen-induced arthritis

41 p.-6 fig.-2 tab.1 gráf.-1 fig. supl. Aragoneses-Fenoll, L. et al.Class IA phosphoinositide 3-kinases (PI3Ks) are essential to function of normal and tumor cells, and to modulate immune responses. T lymphocytes express high levels of p110α and p110δ class IA PI3K. Whereas the functioning of PI3K p110δ in immune and autoimmune reactions is well established, the role of p110α is less well understood. Here, a novel dual p110α/δ inhibitor (ETP-46321) and highly specific p110α (A66) or p110δ (IC87114) inhibitors have been compared concerning T cell activation in vitro, as well as the effect on responses to protein antigen and collagen-induced arthritis in vivo. In vitro activation of naive CD4+ T lymphocytes by anti-CD3 and anti-CD28 was inhibited more effectively by the p110δ inhibitor than by the p110α inhibitor as measured by cytokine secretion (IL-2, IL-10, and IFN-γ), T-bet expression and NFAT activation. In activated CD4+ T cells re-stimulated through CD3 and ICOS, IC87114 inhibited Akt and Erk activation, and the secretion of IL-2, IL-4, IL-17A, and IFN-γ better than A66. The p110α/δ inhibitor ETP-46321, or p110α plus p110δ inhibitors also inhibited IL-21 secretion by differentiated CD4+ T follicular (Tfh) or IL-17-producing (Th17) helper cells. In vivo, therapeutic administration of ETP-46321 significantly inhibited responses to protein antigen as well as collagen-induced arthritis, as measured by antigen-specific antibody responses, secretion of IL-10, IL-17A or IFN-γ, or clinical symptoms. Hence, p110α as well as p110δ Class IA PI3Ks are important to immune regulation; inhibition of both subunits may be an effective therapeutic approach in inflammatory autoimmune diseases like rheumatoid arthritis.Supported by Grants PI13/01809 (to J.M.R.), PI13/02153 (to P.P.) and PI11/00028 (to G.C.) from “Acción Estratégica en Salud, Plan Estatal I+D+i”, Ministerio de Economía y Competitividad (MINECO), Spain; by Grants CIT-090100-2007-48 (Ministerio de Ciencia y Tecnología) and ADE08/90038 (Ministerio de Sanidad, Igualdad y Servicios Sociales) to J.P.; and by Associazione Italiana Ricerca sul Cancro grant IG14430 (AIRC, Milan) and Fondazione Amici di Jean (Turin) to U.D.Peer reviewe

A comparison of reflector antenna designs for wide-angle scanning

Conventional reflector antennas are typically designed for up to + or - 20 beamwidths scan. An attempt was made to stretch this scan range to some + or - 300 beamwidths. Six single and dual reflector antennas were compared. It is found that a symmetrical parabolic reflector with f/D = 2 and a single circular waveguide feed has the minimum scan loss (only 0.6 dB at Theta sub 0 = 8 deg, or a 114 beamwidths scan). The scan is achieved by tilting the parabolic reflector by an angle equal to the half-scan angle. The f/D may be shortened if a cluster 7 to 19 elements instead of one element is used for the feed. The cluster excitation is adjusted for each new beam scan direction to compensate for the imperfect field distribution over the reflector aperture. The antenna can be folded into a Cassegrain configuration except that, due to spillover and blockage considerations, the amount of folding achievable is small

Mid-Infrared Images of Luminous Infrared Galaxies in a Merging Sequence

We report mid-infrared observations of several luminous infrared galaxies (LIGs) carried out with the Infrared Space Observatory. Our sample was chosen to represent different phases of a merger sequence of galaxy-galaxy interaction with special emphasis on early/intermediate stages of merging. The mid-infrared emission of these LIGs shows extended structures for the early and intermediate mergers, indicating that most of the mid-infrared luminosities are not from a central active galactic nucleus (AGN). Both the infrared hardness (indicated by the IRAS 12, 25, and 60 \micron flux density ratios) and the peak-to-total flux density ratios of these LIGs increase as projected separation of these interacting galaxies become smaller, consistent with increasing star formation activities that are concentrated to a smaller area as the merging process advances. These observations provide among the first observational constraint of largely theoretically based scenarios.Comment: 10 pages, 3 figures, please refer to ApJ Letters for the final versio

A comparison of reflector antenna designs for wide-angle scanning

Conventional reflector antennas are typically designed for up to + or - 20 beamwidths scan. An attempt was made to stretch this scan range to some + or - 300 beamwidths. Six single and dual reflector antennas were compared. It is found that a symmetrical parabolic reflector with f/D = 2 and a single circular waveguide feed has the minimum scan loss (only 0.6 dB at Theta sub 0 = 8 deg, or a 114 beamwidths scan). The scan is achieved by tilting the parabolic reflector by an angle equal to the half-scan angle. The f/D may be shortened if a cluster 7 to 19 elements instead of one element is used for the feed. The cluster excitation is adjusted for each new beam scan direction to compensate for the imperfect field distribution over the reflector aperture. The antenna can be folded into a Cassegrain configuration except that, due to spillover and blockage considerations, the amount of folding achievable is small

Low optical polarisation at the core of the optically-thin jet of M87

We study the optical linear and circular polarisation in the optically-thin regime of the core and jet of M87. Observations were acquired two days before the Event Horizon Telescope (EHT) campaign in early April 2017. A high degree ($\sim 20$ per cent) of linear polarisation (P$_{\rm lin}$) is detected in the bright jet knots resolved at $\sim 10\, \rm{arcsec}$ to $23\, \rm{arcsec}$ ($0.8$-$1.8\, \rm{kpc}$) from the centre, whereas the nucleus and inner jet show P$_{\rm lin} \lesssim 5$ per cent. The position angle of the linear polarisation shifts by $\sim 90$ degrees from each knot to the adjacent ones, with the core angle perpendicular to the first knot. The nucleus was in a low level of activity (P$_{\rm lin} \sim 2$-$3$ per cent), and no emission was detected from HST-1. No circular polarisation was detected either in the nucleus or the jet above a $3\sigma$ level of P$_{\rm circ} \leq 1.5$ per cent, discarding the conversion of P$_{\rm lin}$ into P$_{\rm circ}$. A disordered magnetic field configuration or a mix of unresolved knots polarised along axes with different orientations could explain the low P$_{\rm lin}$. The latter implies a smaller size of the core knots, in line with current interferometric observations. Polarimetry with EHT can probe this scenario in the future. A steep increase of both P$_{\rm lin}$ and P$_{\rm circ}$ with increasing frequency is expected for the optically-thin domain, above the turnover point. This work describes the methodology to recover the four Stokes parameters using a $\lambda/4$ wave-plate polarimeter.Comment: Accepted for publication in MNRAS. 10 pages, 8 figure