Based on an advanced dust devil–scale large-eddy simulation (LES) model, the atmosphere flow of a modeled dust devil in a quasi–steady state was first simulated to illustrate the characteristics of the gas phase field in the mature stage, including the prediction of the lower pressure and higher temperature in the vortex core. The dust-lifting physics is examined in two aspects. Through the experimental data analysis, it is verified again that the horizontal swirling wind can only make solid particles saltate along the ground surface. Based on a Lagrangian reference frame, the tracks of dust grains with different density (material) and diameter are calculated to show the effect of dust particles entrained by the vertical swirling wind field. The movement of solid particles depends on the interactions between the aloft dust particles and the airflow field of dust devils, in which the drag and the centrifugal force component on the horizontal plane are the key force components. There is the trend of the fine dust grains rising along the inner helical tracks while the large dust grains are lifting along the outer helical tracks and then descending beyond the corner region, resulting in the impact between different-sized dust grains in the swirling atmospheric flow. This trend will make the dust stratification, developing a top small-sized grain domain and a bottom large-sized grain domain in dust devils.
Large Eddy Simulations (LES) of vertical convective vortices and dust devils in the terrestrial Convective Boundary Layer (CBL) are presented. A CBL-scale simulation and a dust-devil-scale simulation are preformed at different resolutions. The CBL-scale simulation is performed to study the generation of vertical vortices and the dust-devil-scale simulation is performed to study the detailed structures and stages of dust devil development. The simulation results show that dust devils undergo three stages of development as the swirl ratio increases: a weak vortex stage, a single-celled vortex stage and a two-celled vortex stage. The structure of a dust devil can be divided into four regions: outflow, core, corner and inflow layer. The different structures and characteristics of the modelled dust devil during various stages of development and the influence of the surface on the dust devil profile are described using some of the simulation results as illustrations. The causes of the different structures and characteristics are analysed through the interplay between the rotation, the radial pressure gradient, the buoyancy and the axial pressure gradient. Dust devils are a type of concentrated vortex similar to tornadoes. The differences in the structure and characteristics of tornadoes and the modelled dust devils are discussed in this paper. The carrying aloft of sand particles within the modelled dust devil is explored using a Lagrangian coordinate system. Sand particles can be transported by the updraft with particles of varying diameters follow different tracks.
Edited by Peter CresswellThe stable effector functionLess (SEFL) antibody was designed as an IgG1 antibody with a constant region that lacks the ability to interact with Fc␥ receptors. The engineering and stability and pharmacokinetic assessments of the SEFL scaffold is described in the accompanying article (Jacobsen, F. W., Stevenson, R., Li, C., Salimi-Moosavi, H., Liu, L., Wen, J., Luo, Q., Daris, K., Buck, L., Miller, S., Ho, S-Y., Wang, W., Chen, Q., Walker, K., Wypych, J., Narhi, L., and Gunasekaran, K. (2017) J. Biol. Chem. 292). The biological properties of these SEFL antibodies were assessed in a variety of human and cynomolgus monkey in vitro assays. Binding of parent molecules and their SEFL variants to human and cynomolgus monkey Fc␥Rs were evaluated using flow cytometry-based binding assays. The SEFL variants tested showed decreased binding affinity to human and cynomolgus Fc␥Rs compared with the wild-type IgG1 antibody. In addition, SEFL variants demonstrated no antibody-dependent cell-mediated cytotoxicity in vitro against Daudi cells with cynomolgus monkey peripheral blood mononuclear cells, and had minimal complement-dependent cytotoxicity activity similar to that of the negative control IgG2 in a CD20؉ human Raji lymphoma cell line. SEFL mutations eliminated off-target antibody-dependent monocyte phagocytosis of cynomolgus monkey platelets, and cynomolgus platelet activation in vitro. These experiments demonstrate that the SEFL modifications successfully eliminated Fc-associated effector binding and functions.Monoclonal antibodies (mAbs) are the largest class of biopharmaceuticals and have diverse clinical applications (1). The choice of therapeutic mAb isotype to develop (IgG1, IgG2, or IgG4) is dependent on the target (cell surface versus soluble), desired biology, safety (risk of immunogenicity and undesired immunological effects), and manufacturability (expression, formulation, and stability). More than 80% of approved therapeutic mAbs are IgG1 isotypes that target cell surface receptors and are effective for oncology indications (2). For these therapeutic approaches, mAb isotypes that can induce cell killing such as complement-dependent cytotoxicity (CDC) 2 and antibody-dependent cell-mediated cytotoxicity (ADCC) are often desirable (3, 4). However, for non-oncologic indications, therapeutic mAbs without cytotoxic effector function may be more appropriate because cell killing may not be a goal of therapy.The Fc portion of IgG has interaction sites for the effector ligands, including Fc␥ receptors (Fc␥RI, Fc␥RII, and Fc␥RIII), C1q complement, and the neonatal Fc receptor (FcRn). IgG isotypes differentially engage Fc␥ receptors and C1q binding to recruit immune effector functions and initiate cytotoxic effector functions, (either ADCC or CDC (5)). Historically, IgG2 or IgG4 isotypes were thought to have minimal cytotoxic effector function, and have been selected for applications where cytotoxic effector function is not required or desirable (5). However, recent evidence suggests that IgG2 is...
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