Rolling Steps Research Articles

Evaluation of Microstructure and Texture Development in Zr 1.0Nb Sheet during Cold-Rolling

Abstract The effect of manufacturing conditions such as rolling reductions and steps on the texture and microstructure was investigated for an hot-rolled Zr-1.0Nb sheet. The crystallographic texture of the cold-rolled and annealed sheet was examined by X-ray diffraction (XRD) for the rolling plane, and the microstructure was characterized by transmission electron microscopy (TEM) and electron back-scattering diffraction (SEM-EBSD). The results show that the grain size ranges from bimodal distribution to homogeneous distribution with the increase of cold rolling reductions from 30% to 70%. Textural developments are generalized in terms of (0001) and 0> fibers and enhanced by the progressive cold rolling and annealing. The correlation between texture and microstructure developments has been discussed extensively based on the obtained results.

Modeling the texture evolution of Cu/Nb layered composites during rolling

Metallic based multi-layered nano-composites are recognized for their increased plastic flow strength and indentation hardness, increased ductility, improved radiation damage resistance, improved electrical and magnetic properties, and enhanced fatigue failure resistance compared to conventional metallic materials. One of the ways in which these classes of materials are manufactured is through accumulated roll bonding where the material is produced by several rolling and heat treatment steps during which the layer thickness is reduced through severe plastic deformation. In this article, a single rolling pass of the accumulated roll bonding process in which a Cu/Nb layered composite with an initial average layer thickness of 24μm subjected to a 50% height reduction is examined. Experimental morphological and crystallographic texture data is presented and used to initialize numerical models for these layered material systems. This study focuses on the Cu/Nb combination of fcc/bcc materials for incoherent material interfaces. A single crystal model based upon thermally activated dislocation motion is used and the evaluation of material parameters is presented. Since the initial state of the composite is not in a fully annealed condition, nano hardness tests for both the Cu and Nb layers are used to initialize the model for each of the two materials. EBSD data of the heat treated material is used to characterize the initial state of the composite and used to produce 40 combined morphological and crystallographic numerical model realizations of the material. Each of the models is then imposed to a plane strain compression deformation height reduction of 50%. Numerical data from the 40 simulations was then combined to arrive at the statistically comparable crystallographic texture for each of the Cu and Nb materials. This data was compared with the experimental data and the results suggest very good agreement between the predicted and experimental textures for both the materials. Selected stress profile predictions for two realizations are presented and demonstrate a strong difference in stress state between the Cu and Nb layers.

Meso-Scale Modeling the Orientation and Interface Stability of Cu/Nb-Layered Composites by Rolling

Metallic-based multilayered nanocomposites are recognized for their increased plastic flow resistance and indentation hardness, increased ductility, improved radiation damage resistance, improved electrical and magnetic properties, and enhanced fatigue failure resistance compared to conventional metallic materials. One of the ways in which these classes of materials are manufactured is through accumulated roll bonding where the material is produced by several rolling and heat-treatment steps during which the layer thickness is reduced through severe plastic deformation. A single rolling pass of the accumulated roll bonding process in which a Cu/Nb-layered composite with an initial average layer thickness of 24 μm subjected to a 50% height reduction is modeled. A single-crystal model based upon thermally activated dislocation motion is used. Nanohardness tests for both the Cu and Nb layers are used to help initialize the model for each of the two materials. Electron backscatter diffraction (EBSD) data of the heat-treated material is used to characterize the initial state of the composite and to produce 40 combined morphological and crystallographic numerical model realizations of the material. The results suggest very good agreement between the predicted and experimental textures for both the materials. Highly oriented microstructure develops during severe plastic rolling deformation of Cu/Nb nanocomposites. The deformation textures significantly deviate from those expected when rolling Cu or Nb alone, and the Cu/Nb interfaces do not correspond to those with the lowest possible formation energies. We study the interfacial stability of specific Cu/Nb bicrystal configurations under rolling conditions using a finite-element crystal plasticity model. Specifically, we examine how slip activity and lattice reorientation are affected by the kinematic constraint imposed by the interface. Our results show that for certain configurations the slip activity and lattice rotation of the individual crystallites display some sensitivity to the kinematic constraint, yet the overall stability of a given bicrystal can be predicted by the stability of the individual single-crystal orientations. Future work will account for the influence of the bimetal interface on the interface stability and development of enhanced properties.

In vivo modulation of the inflammatory response by nonsteroidal antiinflammatory drug‐related compounds that trigger L‐selectin shedding

Diphenylamine-based nonsteroidal antiinflammatory drugs (NSAIDs) are able to cause in vitro the shedding of L-selectin. The aim of this work was to determine the physio-logic relevance of L-selectin shedding in the antiinflammatory effect exerted by NSAIDs in vivo. Chemical compounds structurally related to NSAIDs - including diphenyl-amine, N-phenylanthranilic acid (N-Ph), diphenylacetic acid - as well as the traditional NSAID indomethacin were studied using the zymosan air-pouch mouse model. Animals intramuscularly pretreated with indomethacin or N-Ph, but not with diphenyl-amine or diphenylacetic acid, showed a significant dose-dependent reduction in the number of neutrophils compared with untreated animals (N-Ph, IC50 = 6.7 mg/kg). Except for indomethacin, none of these compounds caused any significant reduction in cyclooxygenase-1 activity in vivo. In flow chamber experiments, N-Ph reduced the capability of human neutrophils to pass across the endothelial barrier by interfering with leukocyte rolling step on HUVEC. N-Ph, but not diphenylacetic acid, induced activation-independent L-selectin shedding in mouse neutrophils. Interestingly, N-Ph exerted an antiinflammatory effect similar to that of the anti-L-selectin blocking antibody Mel-14, although no additive action was observed when both compounds were combined. These data suggest that the L-selectin shedding induced by NSAIDs may be involved in the antiinflammatory action exerted by these compounds in clinical settings.

Investigations on Interaction between Recrystallization and Precipitation at Finishing Steps of Seamless Tube Rolling

Conventional controlled rolling is normally used in a hot strip mill in order to refine the microstructure and, consequently, to meet a good combination of mechanical strength and toughness in low carbon steels. Nb microalloying are used for this purpose once this rolling technique requires the occurrence of strain induced precipitation before that any recrystallization process takes place. In a hot strip mill, the transfer time between roughing and finishing steps is considered fast enough to keep all Nb, previously solubilized in plate furnace, in solid solution just before finishing. As a consequence, the thermodynamic driving force required for strain induced precipitation remains high, accelerating its kinetics and preventing the occurrence of recrystallization. On the other hand, in a seamless tube rolling, the transfer time between roughing and finishing steps is about 20 times longer than in a hot strip mill. As a consequence, Nb can precipitate in the recrystallized austenite after roughing, decreasing the driving force for strain induced precipitation at finishing. Transmission electron microscopy investigations on samples simulating the material just before finishing rolling in a seamless tube mill show that both grain boundary precipitation and co-precipitation on TiN particles takes place during transfer time. Based on these findings, this paper discusses the effect of long times after roughing steps on the driving force for strain induced precipitation at finishing rolling in seamless tube. Thermo-Calc software was used to evaluate the possible amount of Nb that remains in solid solution just before finishing. Due to previous precipitation, the driving force to be considered in the Dutta-Sellars equations for onset of precipitation decreases and a comparison between recrystallization and precipitation curves shows that recrystallization takes place before the start of strain induce precipitation.

Hydrogen permeation characteristics of rolled V85Al10Co5 alloys

Thin sheets of V85Al10Co5 alloy were produced by a thermo-mechanical treatment consisting in successive hot rolling, cold rolling steps and annealing treatment at high temperature followed by either air cooling or water quenching. Though the values of hydrogen permeability measured for these sheets were significantly reduced as a consequence of the rolling process, the annealing treatment restored almost the hydrogen permeation properties to those of the alloy in the cast condition. EBSD analyses suggested that the post-annealing treatment performed at 1100 °C for 3 min after cold rolling induced a recrystallization of the grains resulting in a preferred orientation along the {002} planes. For the sample annealed and water quenched, the value of the hydrogen flux reached about 45 ml/cm2.min, which is more than twice the value of the flux obtained for thin foils of Pd alloys tested under identical conditions.

Analysis of the Asymmetric Roll Bonding Process by Means of the Slab Method

In asymmetric roll bonding, two metal sheets with dissimilar properties are subject to a rolling step to create a bimetal strip. The paper reviews earlier work in this field which generally uses the upper-bound or finite element methods. The use of the slab method appears simpler than the former, but allows identifying critical aspects of process and model which were not addressed before. To obtain a complete set of equations, the bonding problem must be analysed not only from the cinematic viewpoint, but also from a mechanical one. After defining mechanical equilibrium, one additional cinematic equation is needed to solve the problem, which is obtained by minimising the plastic work in the zone where both sheets deform plastically but are not yet bonded. The new model has the advantage over earlier approaches in that it not only predicts the final thickness of both sheets but also permits to determine whether the bonding is possible under given process conditions. Keywords: Roll Bonding, Cladding, Modelling, Adhesion, Slab method.

Glycomechanics of the Metastatic Cascade: Tumor Cell–Endothelial Cell Interactions in the Circulation

Hydrodynamic shear force plays an important role in the leukocyte adhesion cascade that involves the tethering and rolling of cells along the endothelial layer, their firm adhesion or arrest, and their extravasation or escape from the circulatory system by inducing passive deformation, or cell flattening, and microvilli stretching, as well as regulating the expression, distribution, and conformation of adhesion molecules on leukocytes and the endothelial layer. Similarly, the dissemination of circulating tumor cells (CTCs) from the primary tumor sites is believed to involve tethering, rolling, and firm adhesion steps before their eventual extravasation which leads to secondary tumor sites (metastasis). Of particular importance to both the leukocyte adhesion cascade and the extravasation of CTCs, glycoproteins are involved in all three steps (capture, rolling, and firm adhesion) and consist of a variety of important selectin ligands. This review article provides an overview of glycoprotein glycosylation associated with the abnormal glycan expression on cancer cell surfaces, where well-established and novel selectin ligands that are cancer related are discussed. An overview of computational approaches on the effects of fluid mechanical force on glycoprotein mediated cancer cell rolling and adhesion is presented with a highlight of recent flow-based and selectin-mediated cell capturing/enriching devices. Finally, as an important branch of the glycoprotein family, mucins, specifically MUC1, are discussed in the context of their aberrant expression on cancer cells and their role as cancer cell adhesion molecules. Since metastasis relies heavily on glycoprotein interactions in the bloodstream where the fluid shear stress highly regulates cell adhesion forces, it is important to study and understand the glycomechanics of all relevant glycoproteins (well-established and novel) as they relate to the metastatic cascade.

Rolling simplexes and their commensurability. (Axiom and criterion of incompressibility, momentum lemma)

The total geometrical theory of field is recreated. DOI: 10.3103/S0027132211050093 “Cogito ergo sum.” Rene Descartes It is hard to establish now who first noticed that Newton’s first law can be interpreted as Kepler’s second law for any observer positioned out of the line along which a body moves freely and who tried to restrict himself with axiomatization of spatial properties of natural geodesics in the basic axiomatics of the classical and celestial mechanics in order to keep off the usage of Euclidean metrics. However, there is no doubt that each new generation continues constructions of new variants of the theory of gravitation based again and again on the mathematical apparatus of (Euclidean, Hilbert, etc.) metric spaces, paying no attention on the “golden rule of mechanics” and the “level arm rule”, and demonstrating the persistence deserving a better cause. In this paper we present other (and, in our opinion, weighty) arguments in favor of the moderation in all activities, in particular, it is worth replacing compasses by a set square in solution of construction problems at a certain stage of teaching plane geometry. Let the structure of an abstract projective plane be given on the set M , i.e. (see [1]), a subset L is chosen in the set 2 of all subsets of the set M and it is accepted to call the elements l of this subset straight lines satisfying the following properties (axioms): (P0) each line contains not less than three points; (P1) exactly one line l ∈ L passes trough any two points X,Y ∈ M ; (P2) any two lines l1, l2 ∈ L cross exactly at one point. For any straight line l ∈ L we assume Ml def = M \ l, Ll def = L \ {l} and, as always, call Ml with the system of lines Ll the affine map of the projective plane M , and call l the infinitely distant line. The lines l1, l2 ∈ Ll of the affine plane Ml are parallel if the point of their crossing lies on the infinitely distant line l. Proposition 1. Let the points A,B,C of the affine plane Ml do not lie on the same line. Then any three points A′, B′, C′ can be rolled in a finite number of steps (preserving the “area of ΔA′B′C′” in the intuitive sense)1 so that the result of this rolling of the points A′, B′ coincides with A and B, respectively, and the point C′ appears on the same line with the points B and C. Obviously, in the ordinary model of the affine plane studied in the school course of the planimetry, the following assertions are valid for the rolling process considered here. (RO) (Axiom of incompressibility). If the points A,B,C of the affine plane Ml do not lie on the same line and the point D lies on the same line with B and C, but not coincides with C, then the points A,B,D cannot be rolled to the points A,B,C, respectively. (R1) (Axiom of weak additivity). If the triples of points S,A,A′ and S,B,B′ lie on different lines in the affine plane Ml and the lines passing through A,B and A′, B′ are parallel, then the points S,A′, B can be rolled to the points S,A,B′, respectively. 1At the rolling step we “move” any point from the ordered triple parallel to the line passing through the remaining two points.

Solidification Microstructure and Mechanical Properties of Hot Rolled and Annealed Mg Sheet Produced through Twin Roll Casting Route

The use of wrought magnesium for automobile structural components is an important component of the mass reduction strategy for automobiles to improve their fuel efficiency. Compared to Direct chill casting, Twin Roll Casting (TRC) allows major reduction of hot rolling steps in the production of Mg sheet due to the thin thickness of the as-cast strip. This TRC route can substantially reduce the time and cost to produce Mg alloy sheet product. In this work, AZ31 magnesium alloy was casted to 5 and 6 mm thick strips under different process conditions. Microstructure of these strips was analyzed using optical microscopy, SEM and EPMA. TRC strip was annealed under two different conditions: 2 hours at 330 and 1 hour at 400°C. It has been found that heat treatment at 400°C for 1 hour reduces centerline segregation significantly. TRC strips were rolled down to 2 mm and annealed at 450°C for 2 minutes. The average grain size was 4-6 µm and mechanical properties were comparable with commercial AZ31 sheet.

Real-time Analysis of the Inside-out Regulation of Lymphocyte Function-associated Antigen-1 Revealed Similarities to and Differences from Very Late Antigen-4

Ten years ago, we introduced a fluorescent probe that shed light on the inside-out regulation of one of the major leukocyte integrins, very late antigen-4 (VLA-4, CD49d/CD29). Here we describe the regulation of another leukocyte integrin, lymphocyte function-associated antigen-1 (LFA-1, CD11a/CD18) using a novel small fluorescent probe in real time on live cells. We found that multiple signaling mechanisms regulate LFA-1 conformation in a manner analogous to VLA-4. LFA-1 can be rapidly activated by Gαi-coupled G protein-coupled receptors (GPCRs) and deactivated by Gαs-coupled GPCRs. The effects of Gαs-coupled GPCR agonists can be reversed in real time by receptor-specific antagonists. The specificity of the fluorescent probe binding has been assessed in a competition assay using the natural LFA-1 ligand ICAM-1 and the LFA-1-specific α I allosteric antagonist BIRT0377. Similar to VLA-4 integrin, modulation of the ligand dissociation rate can be observed for different LFA-1 affinity states. However, we also found a striking difference in the binding of the small fluorescent ligand. In the absence of inside-out activation ligand, binding to LFA-1 is extremely slow, at least 10 times slower than expected for diffusion-limited binding. This implies that an additional structural mechanism prevents ligand binding to inactive LFA-1. We propose that such a mechanism explains the inability of LFA-1 to support cell rolling, where the absence of its rapid engagement by a counterstructure in the inactive state leads to a requirement for a selectin-mediated rolling step.

Repetitive Thermomechanical Processing towards Ultra Fine Grain Structure in 301, 304 and 304L Stainless Steels

Thermomechanical processing as a combination of cold rolling and annealing was performed on austenitic stainless steels 301, 304 and 304L. Two cold rolling steps each one up to a reduction of 75% were combined with an intermediate annealing at 800°C for 20 min. The final annealing was performed at the same temperature and time. Cold rolling contributed to martensite formation at the expense of metastable austenite in the studied materials. Austenite in 30l was found to be less stable than that in 304 and 304L. Hence, higher strength characteristics in the as-quenched 301 stainless steels were attributed to the higher volume fraction of martensite. Both α′-martensite and ɛ-martensite were found to form as induced by deformation. However, the intensity of ɛ-martensite increased as the stability of austenite decreased. Annealing after cold rolling led to the reversion of austenite with an ultra fine grained structure in the order of 0.5–1 μm from the strain induced martensite. The final grain size was found to be an inverse function of the amount of strain induced martensite. The thermomechanical processing considerably improved the strength characteristics while the simultaneous decrease of elongation was rather low.

Effects of tube rolling and heat treatment on microstructure and mechanical properties of CLAM rectangular tube

The first wall (FW) of China dual functional lithium lead-test blanket module (DFLL-TBM) for International Thermonuclear Experimental Reactor (ITER) contains rectangular helium flow channels, which will be fabricated by hot isostatic pressing (HIP)-diffusion welding with China low activation martensitic (CLAM) steel plates and rectangular tubes. Study on the rectangular tube fabrication process are being conducted. Rectangular tubes of 15 mm × 20 (inter dimensions of cross section) mm × 2.2 (wall thickness) mm × 1500 (length) mm were produced by hot piercing and cold rolling, and its dimensional deviation met the requirement of TBM assembly. The effects of tube rolling and heat treatment on microstructure and mechanical properties of CLAM rectangular tube were analyzed. It is found that soft annealing heat treatment after tube piercing was a suitable way to improve the ductility of the CLAM steel. The elongation should be less than 15% at every tube rolling step, and the favorable tempering temperature to release the stress caused by tube rolling was 800 °C.

Absence of PAF receptor alters cellular infiltrate but not rolling and adhesion of leukocytes in experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is a condition induced in some susceptible species to the study of multiple sclerosis (MS). The platelet activating factor (PAF) is an important mediator of immune responses and seems to be involved in MS. However, the participation of PAF in EAE and MS remains controversial. Thus, in this study, we aimed to evaluate the role of PAF receptor in the pathogenesis of EAE. EAE was induced using an emulsion containing MOG35–55. EAE-induced PAF receptor knock out (PAFR−/−) mice presented milder disease when compared to C57BL/6 wild type (WT) animals. PAFR−/− animals had lower inflammatory infiltrates in central nervous system (CNS) tissue when compared to WT mice. However, intravital microscopy in cerebral microvasculature revealed similar levels of rolling and adhering leukocytes in both WT and PAFR−/− mice. Interleukine (IL)-17 and chemokines C–C motif legends (CCL)2 and CCL5 were significantly lower in PAFR−/− mice when compared to WT mice. Brain infiltrating cluster of differentiation (CD)4+ leukocytes and IL-17+ leukocytes was diminished in PAFR−/− when compared to WT mice. Taken together, our results suggest that PAF receptor is important in the induction and development of EAE, although it has no influence in rolling and adhesion steps of cell recruitment. The absence of PAF receptor results in milder disease by altering the type of inflammatory mediators and cells that are present in CNS tissue.

Microstructural and Mechanical Characterization after Thermomechanical Treatments in 6063 Aluminum Alloy

The aim of this work is the mechanical and microstructural characterization by optical and electron microscopy as well as microhardness of Al 6063 alloy after mechanical and thermal treatment. Al-Mg based alloys have special attention due to the lightness of the material and certain mechanical properties and recyclability. Such alloys produce good mechanical properties in moderate mechanical efforts (up to 700 MPa) and good resistance to the corrosion. Cold rolling steps (30%, 60% and 90% in area reduction) in Al 6063 alloy were employed for the recrystallization studies, followed by thermal treatment using four isothermal heating (423K, 523K, 623K and 723K) during 1800, 3600, 5400 and 7200s. The direct observation and chemical microanalysis were made in a JEOL200C and JEOL2010 transmission electron microscopes combined with mechanical characterization utilizing Vickers microhardness measurements. Normally classified as non-heat-treatable these alloys obtain higher strength either by strain-hardening or by solid solution. The nucleation of new grains is a non stability of the deformed microstructure, depending on subgrain size heterogeneities present as potential embryos in the deformed state adjacent to high local misorientation. The results indicate a significant effect of second-phase particles on recrystallization and how to control the resulting microstructure and texture by the use of particles. It may be a preferential growth in the early stage due to their local environment or a selection of certain orientations from among those produced by particles stimulated nucleation or a preferential nucleation at particles in favored sites such as grain boundaries.

Microstructure and Properties of Hot Rolled Ti-23Al-17Nb Alloy Sheets

Microstructure and tensile properties of Ti-23Al-17Nb (at%) alloy sheets rolled in (α 2 + B2 + O) phase field with the various heat treatments were studied. Before rolling the microstructure of the billet is B2 phase particles embedded in O phase continuity matrix. The B2 phases are deformed more greatly than α 2/O phases during the same rolling step. The (α 2 + B2) two-phase equiaxed microstructure can be obtained by solution treatment in (α 2 + B2) phase field. The B2 phases become the continuous matrix by recrystallization and growing up of B2 and thus anisotropy caused by rolling can be decreased. The microstructure obtained by solution treatment has better tensile properties than the microstructure gained by subsequent aging treatment in (O+B2) phase field because the O phases precipitate as the block structure during aging and results in the B2 matrix continuity being broken down.

Influence of cross rolling and heat treatment on texture and forming properties of molybdenum sheets

To produce molybdenum sheets or ribbons the metal has to be thermomechanically processed leading to characteristic deformation and recrystallization textures depending on the deformation and/or annealing conditions. The so produced textures have an impact on certain properties of the metal. The present work concentrates on the influence of different rolling processes and the last step of heat treatment on microstructure, texture and the mechanical properties of molybdenum sheets. Usually, unidirectional rolling leads to a strengthening of the main texture component, which for molybdenum is a weak α-fibre with a maximum at the rotated cube component {100} < 110>. This component leads to a strong anisotropy of the mechanical properties in the sheet plane. Cross rolling steps during the thermomechanical process increase the rotated cube component. To decrease the intensity of the rotated cube component and simultaneously increase the intensity of the γ-fibre, specific annealing stages of the final heat treatment were tested. The texture development during these annealing stages is discussed with regard to microstructural changes. The strong differences in the textures measured are reflected in the plastic anisotropy characterized by the Lankford parameters. The Taylor–Bishop–Hill theory is used to qualitatively explain the plastic anisotropy.

Effect of cold rolling on microstructure and magnetic properties in a metastable lean duplex stainless steel

Microstructural and magnetic properties chan- ges of a metastable ferritic-austenitic stainless steel due to cold rolling were studied together with the possibility to develop a new ferritic-martensitic stainless steel. In order to reduce costs low-Ni content was maintained in the lean duplex stainless steel considered, making it more suscep- tible to strain-induced martensitic transformation. In this study a practically complete c ? a 0 transformation was found for 80% of thickness reduction, resulting a new two- phase ferritic-a 0 martensitic stainless steel. To investigate the structural evolution different values of thickness reduction were applied. Light optical and scanning electron microscopy were performed to characterize the morphol- ogy and grain refining of the structure after each rolling step. Martensitic transformation and work hardening were detected and analyzed by studying of magnetic properties (saturation magnetic polarization, relative magnetic per- meability, coercivity). Additionally, hardness tests were performed. The results highlighted a strong grain refining and increase in martensitic phase and hardness with increasing cold deformation. A direct relationship between microstructure and magnetic properties was revealed. In particular the reciprocal of relative magnetic permeability and the coercivity increased with martensite content and the amount of cold deformation. Therefore, the possible application of magnetic measurements as non-destructive tests to study microstructural evolution during cold rolling was shown for the steel considered.

Heterotypic interactions enabled by polarized neutrophil microdomains mediate thromboinflammatory injury.

Selectins and their ligands mediate leukocyte rolling allowing interactions with chemokines that lead to integrin activation and arrest. Here, we demonstrate that E-selectin is critical to induce a secondary wave of activating signals transduced specifically by E-selectin ligand-1, that induces polarized, activated αMβ2 integrin clusters at the leading edge of crawling neutrophils, allowing the capture of circulating erythrocytes or platelets. In a humanized model of sickle cell disease (SCD), the capture of erythrocytes by αMβ2 microdomains leads to acute lethal vascular occlusions. In a model of transfusion-related acute lung injury, polarized neutrophils capture circulating platelets, resulting in the generation of oxidative species that produces vascular damage and lung injury. Inactivation of E-selectin or αMβ2 prevented tissue injury in both inflammatory models, suggesting broad implications of this paradigm in thrombo-inflammatory diseases. These results indicate that endothelial selectins can influence neutrophil behavior beyond its canonical rolling step through delayed, organ-damaging, polarized activation.

Computer‐aided analysis of cell interactions under dynamic flow conditions

Experimentally, initial steps of leucocyte extravasation, including tethering and rolling, are analysed in endothelial cell flow chambers. Given the complexity and speed of endothelial-immune cell interaction, computer-aided advances of this analysis are highly desirable. Herein, we compared two established methods, hand counting and tracking software, with novel analysis software using defined movies recorded at standard conditions of endothelial-leucocyte interactions. As a first validation, cell counts and velocity parameters determined by seven experienced experts revealed no statistic differences to both semi-automated tracking and fully computerized analyses. Nevertheless, interindividual variations were substantial for hand counting. In additional experiments, velocity distributions between 1 and 800 microm/s picked up by the fully computerized analysis matched well with the tracking software as indicated by speed vector histograms. With respect to the time consumed for a defined set of movies, hand counting took 3.6 +/- 1.6 h, tracking software 4.5 +/- 1.2 h, whereas fully automated analysis consumed less than 15 min, reaching real-time mode. Thus, a validated and fully computerized method yielded functional flow chamber data unbiased, independent from an examiner, and reaching high-throughput level, which in turn will allow a substantial progress in understanding this process central for skin inflammation.