Exchange biasing of single-domain Ni nanoparticles spontaneously grown in an antiferromagnetic MnO matrix

Exchange biased composites of ferromagnetic single-domain Ni nanoparticles embedded within large grains of MnO have been prepared by reduction of Ni$_x$Mn$_{1-x}$O$_4$ phases in flowing hydrogen. The Ni precipitates are 15-30 nm in extent, and the majority are completely encased within the MnO matrix. The manner in which the Ni nanoparticles are spontaneously formed imparts a high ferromagnetic- antiferromagnetic interface/volume ratio, which results in substantial exchange bias effects. Exchange bias fields of up to 100 Oe are observed, in cases where the starting Ni content $x$ in the precursor Ni$_x$Mn$_{1-x}$O$_4$ phase is small. For particles of approximately the same size, the exchange bias leads to significant hardening of the magnetization, with the coercive field scaling nearly linearly with the exchange bias field.Comment: 6 pages PDFLaTeX with 9 figure

Regulation of eosinophilia and allergic airway inflammation by the glycan-binding protein galectin-1

Galectin-1 (Gal-1), a glycan-binding protein with broad antiinflammatory activities, functions as a proresolving mediator in autoimmune and chronic inflammatory disorders. However, its role in allergic airway inflammation has not yet been elucidated. We evaluated the effects of Gal-1 on eosinophil function and its role in a mouse model of allergic asthma. Allergen exposure resulted in airway recruitment of Gal-1-expressing inflammatory cells, including eosinophils, as well as increased Gal-1 in extracellular spaces in the lungs. In vitro, extracellular Gal-1 exerted divergent effects on eosinophils that were N-glycan- And dose-dependent. At concentrations ≤0.25 μM, Gal-1 increased eosinophil adhesion to vascular cell adhesion molecule-1, caused redistribution of integrin CD49d to the periphery and cell clustering, but inhibited ERK(1/2) activation and eotaxin-1-induced migration. Exposure to concentrations ≥1 μM resulted in ERK(1/2)- dependent apoptosis and disruption of the F- Actin cytoskeleton. At lower concentrations, Gal-1 did not alter expression of adhesion molecules (CD49d, CD18, CD11a, CD11b, L-selectin) or of the chemokine receptor CCR3, but decreased CD49d and CCR3 was observed in eosinophils treated with higher concentrations of this lectin. In vivo, allergen-challenged Gal-1-deficient mice exhibited increased recruitment of eosinophils and CD3+ T lymphocytes in the airways as well as elevated peripheral blood and bone marrow eosinophils relative to corresponding WT mice. Further, these mice had an increased propensity to develop airway hyperresponsiveness and displayed significantly elevated levels of TNF-α in lung tissue. This study suggests that Gal-1 can limit eosinophil recruitment to allergic airways and suppresses airway inflammation by inhibiting cell migration and promoting eosinophil apoptosis.Fil: Ge, Xiao Na. University of Minnesota; Estados UnidosFil: Ha, Sung Gil. University of Minnesota; Estados UnidosFil: Greenberg, Yana G.. University of Minnesota; Estados UnidosFil: Rao, Amrita. University of Minnesota; Estados UnidosFil: Bastan, Idil. University of Minnesota; Estados UnidosFil: Blidner, Ada Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Rao, Savita P.. University of Minnesota; Estados UnidosFil: Rabinovich, Gabriel Adrián. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Sriramarao, P.. University of Minnesota; Estados Unido

Egg shape changes at the theropod–bird transition, and a morphometric study of amniote eggs

The eggs of amniotes exhibit a remarkable variety of shapes, from spherical to elongate and from symmetrical to asymmetrical. We examine eggshell geometry in a diverse sample of fossil and living amniotes using geometric morphometrics and linear measurements. Our goal is to quantify patterns of morphospace occupation and shape variation in the eggs of recent through to Mesozoic birds (neornithe plus non-neornithe avialans), as well as in eggs attributed to non-avialan theropods. In most amniotes, eggs show significant deviation from sphericity, but departure from symmetry around the equatorial axis is mostly confined to theropods and birds. Mesozoic bird eggs differ significantly from extant bird eggs, but extinct Cenozoic bird eggs do not. This suggests that the range of egg shapes in extant birds had already been attained in the Cenozoic. We conclude with a discussion of possible biological factors imparting variation to egg shapes during their formation in the oviduct

Droplet actuation induced by coalescence: experimental evidences and phenomenological modeling

This paper considers the interaction between two droplets placed on a substrate in immediate vicinity. We show here that when the two droplets are of different fluids and especially when one of the droplet is highly volatile, a wealth of fascinating phenomena can be observed. In particular, the interaction may result in the actuation of the droplet system, i.e. its displacement over a finite length. In order to control this displacement, we consider droplets confined on a hydrophilic stripe created by plasma-treating a PDMS substrate. This controlled actuation opens up unexplored opportunities in the field of microfluidics. In order to explain the observed actuation phenomenon, we propose a simple phenomenological model based on Newton's second law and a simple balance between the driving force arising from surface energy gradients and the viscous resistive force. This simple model is able to reproduce qualitatively and quantitatively the observed droplet dynamics

Male Competition Reverses Female Preference For Male Chemical Cues

Females must choose among potential mates with different phenotypes in a variety of social contexts. Many male traits are inherent and unchanging, but others are labile to social context. Competition, for example, can cause physiological changes that reflect recent wins and losses that fluctuate throughout time. We may expect females to respond differently to males depending on the outcome of their most recent fight. In Bolitotherus cornutus (forked fungus beetles), males compete for access to females, but copulation requires female cooperation. In this study, we use behavioral trials to determine whether females use chemical cues to differentiate between males and whether the outcome of recent male competition alters female preference. We measured female association time with chemical cues of two size‐matched males both before and after male–male competition. Females in our study preferred to associate with future losers before males interacted, but changed their preference for realized winners following male competitive interactions. Our study provides the first evidence of change in female preference based solely on the outcome of male–male competition

Can airborne ultrasound monitor bubble size in chocolate?

Aerated chocolate products consist of solid chocolate with the inclusion of bubbles and are a popular consumer product in many countries. The volume fraction and size distribution of the bubbles has an effect on their sensory properties and manufacturing cost. For these reasons it is important to have an online real time process monitoring system capable of measuring their bubble size distribution. As these products are eaten by consumers it is desirable that the monitoring system is non contact to avoid food contaminations. In this work we assess the feasibility of using an airborne ultrasound system to monitor the bubble size distribution in aerated chocolate bars. The experimental results from the airborne acoustic experiments were compared with theoretical results for known bubble size distributions using COMSOL Multiphysics. This combined experimental and theoretical approach is used to develop a greater understanding of how ultrasound propagates through aerated chocolate and to assess the feasibility of using airborne ultrasound to monitor bubble size distribution in these systems. The results indicated that a smaller bubble size distribution would result in an increase in attenuation through the product

CCL2 recruits inflammatory monocytes to facilitate breast-tumour metastasis

Macrophages abundantly found in the tumor microenvironment enhance malignancy(1). At metastatic sites a distinct population of metastasis associated macrophages (MAMs) promote tumor cell extravasation, seeding and persistent growth(2). Our study has defined the origin of these macrophages by showing Gr1+ inflammatory monocytes (IMs) are preferentially recruited to pulmonary metastases but not primary mammary tumors, a process also found for human IMs in pulmonary metastases of human breast cancer cells. The recruitment of these CCR2 (receptor for chemokine CCL2) expressing IMs and subsequently MAMs and their interaction with metastasizing tumor cells is dependent on tumor and stromal synthesized CCL2 (FigS1). Inhibition of CCL2/CCR2 signaling using anti-CCL2 antibodies blocks IM recruitment and inhibits metastasis in vivo and prolongs the survival of tumor-bearing mice. Depletion of tumor cell-derived CCL2 also inhibits metastatic seeding. IMs promote tumor cell extravasation in a process that requires monocyte-derived VEGF. CCL2 expression and macrophage infiltration are correlated with poor prognosis and metastatic disease in human breast cancer (Fig S2)(3-6). Our data provides the mechanistic link between these two clinical associations and indicates new therapeutic targets for treating metastatic breast disease

The coordination of cell growth during fission yeast mating requires Ras1-GTP hydrolysis

The spatial and temporal control of polarity is fundamental to the survival of all organisms. Cells define their polarity using highly conserved mechanisms that frequently rely upon the action of small GTPases, such as Ras and Cdc42. Schizosaccharomyces pombe is an ideal system with which to study the control of cell polarity since it grows from defined tips using Cdc42-mediated actin remodeling. Here we have investigated the importance of Ras1-GTPase activity for the coordination of polarized cell growth during fission yeast mating. Following pheromone stimulation, Ras1 regulates both a MAPK cascade and the activity of Cdc42 to enable uni-directional cell growth towards a potential mating partner. Like all GTPases, when bound to GTP, Ras1 adopts an active conformation returning to an inactive state upon GTP-hydrolysis, a process accelerated through interaction with negative regulators such as GAPs. Here we show that, at low levels of pheromone stimulation, loss of negative regulation of Ras1 increases signal transduction via the MAPK cascade. However, at the higher concentrations observed during mating, hyperactive Ras1 mutations promote cell death. We demonstrate that these cells die due to their failure to coordinate active Cdc42 into a single growth zone resulting in disorganized actin deposition and unsustainable elongation from multiple tips. These results provide a striking demonstration that the deactivation stage of Ras signaling is fundamentally important in modulating cell polarity

Phase-field approach to polycrystalline solidification including heterogeneous and homogeneous nucleation

Advanced phase-field techniques have been applied to address various aspects of polycrystalline solidification including different modes of crystal nucleation. The height of the nucleation barrier has been determined by solving the appropriate Euler-Lagrange equations. The examples shown include the comparison of various models of homogeneous crystal nucleation with atomistic simulations for the single component hard-sphere fluid. Extending previous work for pure systems (Gránásy L, Pusztai T, Saylor D and Warren J A 2007 Phys. Rev. Lett. 98 art no 035703), heterogeneous nucleation in unary and binary systems is described via introducing boundary conditions that realize the desired contact angle. A quaternion representation of crystallographic orientation of the individual particles (outlined in Pusztai T, Bortel G and Gránásy L 2005 Europhys. Lett. 71 131) has been applied for modeling a broad variety of polycrystalline structures including crystal sheaves, spherulites and those built of crystals with dendritic, cubic, rhombododecahedral, truncated octahedral growth morphologies. Finally, we present illustrative results for dendritic polycrystalline solidification obtained using an atomistic phase-field model

Mfn2 downregulation in excitotoxicity causes mitochondrial dysfunction and delayed neuronal death.

Mitochondrial fusion and fission is a dynamic process critical for the maintenance of mitochondrial function and cell viability. During excitotoxicity neuronal mitochondria are fragmented, but the mechanism underlying this process is poorly understood. Here, we show that Mfn2 is the only member of the mitochondrial fusion/fission machinery whose expression is reduced in in vitro and in vivo models of excitotoxicity. Whereas in cortical primary cultures, Drp1 recruitment to mitochondria plays a primordial role in mitochondrial fragmentation in an early phase that can be reversed once the insult has ceased, Mfn2 downregulation intervenes in a delayed mitochondrial fragmentation phase that progresses even when the insult has ceased. Downregulation of Mfn2 causes mitochondrial dysfunction, altered calcium homeostasis, and enhanced Bax translocation to mitochondria, resulting in delayed neuronal death. We found that transcription factor MEF2 regulates basal Mfn2 expression in neurons and that excitotoxicity-dependent degradation of MEF2 causes Mfn2 downregulation. Thus, Mfn2 reduction is a late event in excitotoxicity and its targeting may help to reduce excitotoxic damage and increase the currently short therapeutic window in stroke