92 research outputs found

    Experimental investigation of planar strained methane-air and ethylene-air flames

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    The extinction of planar strained methane-air flames in the stagnation-point flow is studied. A thermal analysis has been conducted in order to build a new copper stagnation plate which can be heated up to 1000K, and allows investigation of downstream heat loss as extinction driving mechanism. Since premixed stagnation flames are mostly sensitive to the composition of the mixture, axial velocity and CH radical profiles are simultaneously measured for different equivalence ratios, using respectively Particle Streak Velocimetry (PSV) and Planar Laser Induced Fluorescence (PLIF). These are compared to simulations using CANTERA stagnation flow code with a multicomponent molecular transport model, with the following chemical kinetics mechanisms: GRI-MECH 3.0, the C3-Davis, San-Diego 200308 and San-Diego 200503 mechanisms. In methane-air flames, simulations accurately predict the velocity and CH profiles from Phi=0.8 to Phi=1.2, but the flame speed turns out to be overpredicted at Phi=0.7 by all mechanisms except the C3-Davis mechanism (see Bergthorson et al. 2005a). The experiment at Phi=1.3 would need to be reconducted. Also, measured relative concentrations of CH are compared to numerical predictions using each of the four mechanisms cited above. Composition variations impact on ethylene-air flames was also investigated due to a peculiar jump in the overprediction of flame velocities from Phi=1.6 to Phi=1.8 (Bergthorson 2005). This peculiar feature was found to be repeatable, but the cause remains unclear. Methane-air laminar flame speeds Su0 were computed using CANTERA freely propagating flame code for the following chemical kinetics mechanisms: GRI-MECH 3.0, the C3-Davis mechanism, the San Diego 200308, 200503, and 200506 mechanisms, for variable pressures (1,2,5,10,20 atm) and equivalence ratios (0.6-1.4). Even for methane, whose chemistry is one of the best understood, the scatter between the different mechanisms is significant. Both composition and pressure were found to affect Su0 substantially, although composition variations seem to excite the differences in the predictions among the different mechanisms the most

    Fouling and Cleaning of Modified Stainless Steel Plate Heat Exchangers Processing Milk Products

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    Fouling of heat exchangers in dairy industries is still quite a severe problem both technically and economically. Altering the surface properties of the heating surfaces would be a way of solving this issue. Modified steel surfaces were tested in an Alfa Laval V2 plate heat exchanger throughout dairy product sterilization. The behavior was analyzed for 8 different surface treatments, such as coatings (Diamond Like Carbon [DLC], Silica, SiOX, Ni-P-PTFE, Excalibur®, Xylan®) and ion implantation (SiF+, MoS2). All fouling and cleaning experiments were carried out in standard and well-controlled operating conditions. After fouling, no significant difference could be seen between all the modified steels and the reference by statistical variance analysis. Cleaning efficiency of Ni-PPTFE appeared significantly the best. It could be suggested that the free surface energy plays a predominant role and the roughness a minor role in the level of fouling and cleaning efficiency

    Kidney single-cell atlas reveals myeloid heterogeneity in progression and regression of kidney disease

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    Background Little is known about the roles of myeloid cell subsets in kidney injury and in the limited ability of the organ to repair itself. Characterizing these cells based only on surface markers using flow cytometry might not provide a full phenotypic picture. Defining these cells at the single-cell, transcriptomic level could reveal myeloid heterogeneity in the progression and regression of kidney disease. Methods Integrated droplet– and plate-based single-cell RNA sequencing were used in the murine, reversible, unilateral ureteric obstruction model to dissect the transcriptomic landscape at the single-cell level during renal injury and the resolution of fibrosis. Paired blood exchange tracked the fate of monocytes recruited to the injured kidney. Results A single-cell atlas of the kidney generated using transcriptomics revealed marked changes in the proportion and gene expression of renal cell types during injury and repair. Conventional flow cytometry markers would not have identified the 12 myeloid cell subsets. Monocytes recruited to the kidney early after injury rapidly adopt a proinflammatory, profibrotic phenotype that expresses Arg1, before transitioning to become Ccr21 macrophages that accumulate in late injury. Conversely, a novel Mmp121 macrophage subset acts during repair. Conclusions Complementary technologies identified novel myeloid subtypes, based on transcriptomics in single cells, that represent therapeutic targets to inhibit progression or promote regression of kidney disease

    Might Depression, Psychosocial Adversity, and Limited Social Assets Explain Vulnerability to and Resistance against Violent Radicalisation?

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    BACKGROUND: This study tests whether depression, psychosocial adversity, and limited social assets offer protection or suggest vulnerability to the process of radicalisation. METHODS: A population sample of 608 men and women of Pakistani or Bangladeshi origin, of Muslim heritage, and aged 18-45 were recruited by quota sampling. Radicalisation was measured by 16 questions asking about sympathies for violent protest and terrorism. Cluster analysis of the 16 items generated three groups: most sympathetic (or most vulnerable), most condemning (most resistant), and a large intermediary group that acted as a reference group. Associations were calculated with depression (PHQ9), anxiety (GAD7), poor health, and psychosocial adversity (adverse life events, perceived discrimination, unemployment). We also investigated protective factors such as the number social contacts, social capital (trust, satisfaction, feeling safe), political engagement and religiosity. RESULTS: Those showing the most sympathy for violent protest and terrorism were more likely to report depression (PHQ9 score of 5 or more; RR = 5.43, 1.35 to 21.84) and to report religion to be important (less often said religion was fairly rather than very important; RR = 0.08, 0.01 to 0.48). Resistance to radicalisation measured by condemnation of violent protest and terrorism was associated with larger number of social contacts (per contact: RR = 1.52, 1.26 to 1.83), less social capital (RR = 0.63, 0.50 to 0.80), unavailability for work due to housekeeping or disability (RR = 8.81, 1.06 to 37.46), and not being born in the UK (RR = 0.22, 0.08 to 0.65). CONCLUSIONS: Vulnerability to radicalisation is characterised by depression but resistance to radicalisation shows a different profile of health and psychosocial variables. The paradoxical role of social capital warrants further investigation

    The London Classification: Improving Characterization and Classification of Anorectal Function with Anorectal Manometry.

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    PURPOSE OF REVIEW: Objective measurement of anorectal sensorimotor function is a requisite component in the clinical evaluation of patients with intractable symptoms of anorectal dysfunction. Regrettably, the utility of the most established and widely employed investigations for such measurement (anorectal manometry (ARM), rectal sensory testing and the balloon expulsion test) has been limited by wide variations in clinical practice. RECENT FINDINGS: This article summarizes the recently published International Anorectal Physiology Working Group (IAPWG) consensus and London Classification of anorectal disorders, together with relevant allied literature, to provide guidance on the indications for, equipment, protocol, measurement definitions and results interpretation for ARM, rectal sensory testing and the balloon expulsion test. The London Classification is a standardized method and nomenclature for description of alterations in anorectal motor and sensory function using office-based investigations, adoption of which should bring much needed harmonization of practice

    Size constancy is preserved but afterimages are prolonged in typical individuals with higher degrees of self-reported autistic traits

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    Deficits in perceptual constancies from early infancy have been proposed to contribute to autism and exacerbate its symptoms (Hellendoorn et al., Frontiers in Psychology 6:1–16, 2015). Here, we examined size constancy in adults from the general population (N = 106) with different levels of self-reported autistic traits using an approach based on negative afterimages. The afterimage strength, as indexed by duration and vividness, was also quantified. In opposition to the Hellendoorn and colleagues’ model, we were unable to demonstrate any kind of relationship between abilities in size constancy and autistic traits. However, our results demonstrated that individuals with higher degrees of autistic traits experienced more persistent afterimages. We discuss possible retinal and post-retinal explanations for prolonged afterimages in people with higher levels of autistic traits

    Integrin-Alpha IIb Identifies Murine Lymph Node Lymphatic Endothelial Cells Responsive to RANKL

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    Microenvironment and activation signals likely imprint heterogeneity in the lymphatic endothelial cell (LEC) population. Particularly LECs of secondary lymphoid organs are exposed to different cell types and immune stimuli. However, our understanding of the nature of LEC activation signals and their cell source within the secondary lymphoid organ in the steady state remains incomplete. Here we show that integrin alpha 2b (ITGA2b), known to be carried by platelets, megakaryocytes and hematopoietic progenitors, is expressed by a lymph node subset of LECs, residing in medullary, cortical and subcapsular sinuses. In the subcapsular sinus, the floor but not the ceiling layer expresses the integrin, being excluded from ACKR4+LECs but overlapping with MAdCAM-1 expression. ITGA2b expression increases in response to immunization, raising the possibility that heterogeneous ITGA2b levels reflect variation in exposure to activation signals. We show that alterations of the level of receptor activator of NF-κB ligand (RANKL), by overexpression, neutralization or deletion from stromal marginal reticular cells, affected the proportion of ITGA2b+LECs. Lymph node LECs but not peripheral LECs express RANK. In addition, we found that lymphotoxin-β receptor signaling likewise regulated the proportion of ITGA2b+LECs. These findings demonstrate that stromal reticular cells activate LECs via RANKL and support the action of hematopoietic cell-derived lymphotoxin

    Rank signaling links the development of invariant γδ T cell progenitors and Aire(+) medullary epithelium

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    The thymic medulla provides a specialized microenvironment for the negative selection of T cells, with the presence of autoimmune regulator (Aire)-expressing medullary thymic epithelial cells (mTECs) during the embryonic-neonatal period being both necessary and sufficient to establish long-lasting tolerance. Here we showed that emergence of the first cohorts of Aire(+) mTECs at this key developmental stage, prior to αβ T cell repertoire selection, was jointly directed by Rankl(+) lymphoid tissue inducer cells and invariant Vγ5(+) dendritic epidermal T cell (DETC) progenitors that are the first thymocytes to express the products of gene rearrangement. In turn, generation of Aire(+) mTECs then fostered Skint-1-dependent, but Aire-independent, DETC progenitor maturation and the emergence of an invariant DETC repertoire. Hence, our data attributed a functional importance to the temporal development of Vγ5(+) γδ T cells during thymus medulla formation for αβ T cell tolerance induction and demonstrated a Rank-mediated reciprocal link between DETC and Aire(+) mTEC maturation
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