365 research outputs found

    Blocking neutrophil integrin activation prevents ischemia-reperfusion injury.

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    Neutrophil recruitment, mediated by β2 integrins, combats pyogenic infections but also plays a key role in ischemia-reperfusion injury and other inflammatory disorders. Talin induces allosteric rearrangements in integrins that increase affinity for ligands (activation). Talin also links integrins to actin and other proteins that enable formation of adhesions. Structural studies have identified a talin1 mutant (L325R) that perturbs activation without impairing talin's capacity to link integrins to actin and other proteins. Here, we found that mice engineered to express only talin1(L325R) in myeloid cells were protected from renal ischemia-reperfusion injury. Dissection of neutrophil function in vitro and in vivo revealed that talin1(L325R) neutrophils had markedly impaired chemokine-induced, β2 integrin-mediated arrest, spreading, and migration. Surprisingly, talin1(L325R) neutrophils exhibited normal selectin-induced, β2 integrin-mediated slow rolling, in sharp contrast to the defective slow rolling of neutrophils lacking talin1 or expressing a talin1 mutant (W359A) that blocks talin interaction with integrins. These studies reveal the importance of talin-mediated activation of integrins for renal ischemia-reperfusion injury. They further show that neutrophil arrest requires talin recruitment to and activation of integrins. However, although neutrophil slow rolling requires talin recruitment to integrins, talin-mediated integrin activation is dispensable

    Constraining visible neutrino decay at KamLAND and JUNO

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    We study visible neutrino decay at the reactor neutrino experiments KamLAND and, JUNO. Assuming the Majoron model of neutrino decay, we obtain constraints on the couplings between Majoron and neutrino as well as on the lifetime/mass of the most massive neutrino state i.e., τ3/m3\tau_{3} / m_{3} or τ2/m2\tau_{2} / m_{2}, respectively, for the normal or the inverted mass orderings. We obtain the constraints on the lifetime τ2/m21.4×109 s/eV\tau_{2} / m_{2} \geq 1.4 \times 10^{-9}~\rm{s/eV} in the inverted mass ordering for both KamLAND and JUNO at 90% CL. In the normal ordering in which the bound can be obtained for JUNO only, the constraint is milder than the inverted ordering case, τ3/m31.0×1010 s/eV\tau_{3} / m_{3} \geq 1.0 \times 10^{-10}~\rm{s/eV} at 90% CL. We find that the dependence of lightest neutrino mass (=mlightest=m_{\rm{lightest}}), m1(m3)m_1 (m_3) for the normal (inverted) mass ordering, on the constraints for the different types of couplings (scalar or pseudo-scalar) is rather strong, but the mlightestm_{\rm{lightest}} dependence on the lifetime/mass bound is only modest.Comment: Matches the published version. Minor changes in the tex

    Catch bonds govern adhesion through L-selectin at threshold shear

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    Flow-enhanced cell adhesion is an unexplained phenomenon that might result from a transport-dependent increase in on-rates or a force-dependent decrease in off-rates of adhesive bonds. L-selectin requires a threshold shear to support leukocyte rolling on P-selectin glycoprotein ligand-1 (PSGL-1) and other vascular ligands. Low forces decrease L-selectin–PSGL-1 off-rates (catch bonds), whereas higher forces increase off-rates (slip bonds). We determined that a force-dependent decrease in off-rates dictated flow-enhanced rolling of L-selectin–bearing microspheres or neutrophils on PSGL-1. Catch bonds enabled increasing force to convert short-lived tethers into longer-lived tethers, which decreased rolling velocities and increased the regularity of rolling steps as shear rose from the threshold to an optimal value. As shear increased above the optimum, transitions to slip bonds shortened tether lifetimes, which increased rolling velocities and decreased rolling regularity. Thus, force-dependent alterations of bond lifetimes govern L-selectin–dependent cell adhesion below and above the shear optimum. These findings establish the first biological function for catch bonds as a mechanism for flow-enhanced cell adhesion

    Urban Swarms: A new approach for autonomous waste management

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    Modern cities are growing ecosystems that face new challenges due to the increasing population demands. One of the many problems they face nowadays is waste management, which has become a pressing issue requiring new solutions. Swarm robotics systems have been attracting an increasing amount of attention in the past years and they are expected to become one of the main driving factors for innovation in the field of robotics. The research presented in this paper explores the feasibility of a swarm robotics system in an urban environment. By using bio-inspired foraging methods such as multi-place foraging and stigmergy-based navigation, a swarm of robots is able to improve the efficiency and autonomy of the urban waste management system in a realistic scenario. To achieve this, a diverse set of simulation experiments was conducted using real-world GIS data and implementing different garbage collection scenarios driven by robot swarms. Results presented in this research show that the proposed system outperforms current approaches. Moreover, results not only show the efficiency of our solution, but also give insights about how to design and customize these systems.Comment: Manuscript accepted for publication in IEEE ICRA 201

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    Characterization of the gas-liquid interfacial waves in vertical upward co-current annular flows

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    [EN] For more than fifty years, hundreds of research works have focused on the study of annular flow because of its huge importance in many industrial processes, for instance, chemical, petroleum, etc., being of particular interest in nuclear industry. Specifically, interfacial waves play a vital role in the mass, momentum and energy transference processes between gas and liquid phases. This paper describes the new experimental measurements of vertical upward co-current two-phase gas-liquid flow carried out in a tube with an inner diameter of 44 mm. The liquid film thickness and the major characteristics of the interfacial waves have been measured using a non-intrusive instrument, a conductance probe. The physical phenomenon in which this device is based is the change in the electrical conductivity between air and water, i.e., the electrical signal collected in the sensor receiver depends on the thickness of the liquid film layer. The experimental measurements range from 2000 to 3500 l/min for the gas volumetric flow rate, and from 4 to 10 l/min for the liquid volumetric flow rate. Correlation of the experimental measurements of liquid film thickness and the major properties of the interfacial waves have been analyzed using non-dimensional numbers. An important part of the document focuses on the comparison of the experimental data and the fitting correlations against several of the most widely used expressions. Throughout this paper, in addition to present all the available correlations, the existing scattering found when comparing against other expressions have been also confirmed, underlining the existence of gaps of knowledge even today. Emphasize that the proposed correlations are the ones that better fit the data of all experimental series carried out under the present study for the analyzed variables, with almost all the experimental points covered by the +/- 10% error bands of the new correlations.The authors are indebted to the plan of I+D support of the EXMOTRANSIN project ENE2016-79489-C2-1-P.Cuadros-Orón, JL.; Rivera-Durán, Y.; Berna, C.; Escrivá, A.; Muñoz-Cobo, JL.; Monrós-Andreu, G.; Chiva, S. (2019). Characterization of the gas-liquid interfacial waves in vertical upward co-current annular flows. Nuclear Engineering and Design. 346:112-130. https://doi.org/10.1016/j.nucengdes.2019.03.008S11213034

    Differential regulation of the attachment of KSHV infected human B cells to ECM by KSHV encoded gB and cellular alpha-V integrins

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    Kaposi’s sarcoma-associated herpesvirus (KSHV) has two modes replication: latent and lytic replication. Reactivation from latency is dictated, in part, by the cell cycle. Herein, we have attempted to delineate the importance of cell cycle in KSHV pathogenesis by exploring the expression pattern of cell surface receptors during different phases of the cell cycle. αV integrin expression is augmented during S phase in fibroblasts, epithelial, and KSHV infected cells. Using a Matrigel system, we pioneer the concept that KSHV infected primary effusion lymphoma (PEL) cells can attach to extracellular matrix proteins. This attachment is mediated primarily via αV integrins or virally encoded gB, and occurs preferentially in cells from S phase or cells from S phase actively supporting a lytic infection, respectively. Such an ability of infected B cells to attach to endothelial cells may also aid in the dissemination of infection. The keystone of this work is that for the first time, we describe the ability of KSHV infected B cells to preferentially use cellular (αV) or viral (gB) receptors to specifically bind cells, depending upon the stage of the cell cycle and infection. Originally published Cellular Microbiology, Vol. 10, No. 7, July 200

    Evaluation of the silver species nature in Ag-ITQ2 zeolites by the CO oxidation reaction

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    The authors thank the Spanish Ministry of Economy and Competitiveness through RTI2018-101784-B-I00 (MINECO/FEDER) and SEV-2016-0683 projects for the financial support. We gratefully acknowledge ALBA synchrotron for allocating beamtime (proposal 2015091414) and the CLAESS beamline staff for their help and technical support during our experiment. CG and NB thank the TUW Innovative Project GIP165CDGC. CG, SP, VT, NB and GR are thankful for financial support from the Austrian Science Fund (FWF) through projects DK+ Solids4Fun (W1243) and ComCat (I 1041-N28). I. Lopez Hernandez is grateful to Generalitat Valenciana and European Social Fund for the pre doctoral grant ACIF2017.López-Hernández, I.; García Yago, CI.; Truttmann, V.; Pollit, S.; Barrabés, N.; Rupprechter, G.; Rey Garcia, F.... (2020). Evaluation of the silver species nature in Ag-ITQ2 zeolites by the CO oxidation reaction. 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