Supercooled Liquids Under Shear: Theory and Simulation

We analyze the behavior of supercooled fluids under shear both theoretically and numerically. Theoretically, we generalize the mode-coupling theory of supercooled fluids to systems under stationary shear flow. Our starting point is the set of generalized fluctuating hydrodynamic equations with a convection term. A nonlinear integro-differential equation for the intermediate scattering function is constructed. This theory is applied to a two-dimensional colloidal suspension. The shear rate dependence of the intermediate scattering function and the shear viscosity is analyzed. We have also performed extensive numerical simulations of a two-dimensional binary liquid with soft-core interactions near, but above, the glass transition temperature. Both theoretical and numerical results show: (i) A drastic reduction of the structural relaxation time and the shear viscosity due to shear. Both the structural relaxation time and the viscosity decrease as $\dot{\gamma}^{-\nu}$ with an exponent $\nu \leq 1$, where $\dot{\gamma}$ is the shear rate. (ii) Almost isotropic dynamics regardless of the strength of the anisotropic shear flow.Comment: 14 pages, 14 figure

Supercooled liquids under shear: A mode-coupling theory approach

We generalize the mode-coupling theory of supercooled fluids to systems under stationary shear flow. Our starting point is the generalized fluctuating hydrodynamic equations with a convection term. The method is applied to a two dimensional colloidal suspension. The shear rate dependence of the intermediate scattering function and shear viscosity is analyzed. The results show a drastic reduction of the structural relaxation time due to shear and strong shear thinning behavior of the viscosity which are in qualitative agreement with recent simulations. The microscopic theory with minimal assumptions can explain the behavior far beyond the linear response regime.Comment: 4 pages, 2 figures, Proceedings to Slow Dynamics in Complex Systems November3-8, 2003 -- Sendai, Japa

Supercooled Liquids under Shear: Computational Approach

We have performed molecular dynamics simulations for a model two-dimensional soft-core mixture in a supercooled state. The mixture exhibits a slow structural relaxation in a quiescent state, however, the relaxation is much enhanced in sheared states. There observed surprisingly small anisotropy both in the coherent and incoherent density correlation functions even under extremely strong shear which is $10^3$ times faster than the structural relaxation rate. The present simulation results agree well with predictions of the recently developed mode-coupling theory in shear.Comment: 2 pages, 2 figure

Targeting oxytocin receptor (Oxtr)-expressing neurons in the lateral septum to restore social novelty in autism spectrum disorder mouse models

© 2020, The Author(s). Autism spectrum disorder (ASD) is a continuum of neurodevelopmental disorders and needs new therapeutic approaches. Recently, oxytocin (OXT) showed potential as the first anti-ASD drug. Many reports have described the efficacy of intranasal OXT therapy to improve the core symptoms of patients with ASD; however, the underlying neurobiological mechanism remains unknown. The OXT/oxytocin receptor (OXTR) system, through the lateral septum (LS), contributes to social behavior, which is disrupted in ASD. Therefore, we selectively express hM3Dq in OXTR-expressing (OXTR+) neurons in the LS to investigate this effect in ASD mouse models developed by environmental and genetic cues. In mice that received valproic acid (environmental cue), we demonstrated successful recovery of impaired social memory with three-chamber test after OXTR+ neuron activation in the LS. Application of a similar strategy to Nl3R451C knock-in mice (genetic cue) also caused successful recovery of impaired social memory in single field test. OXTR+ neurons in the LS, which are activated by social stimuli, are projected to the CA1 region of the hippocampus. This study identified a candidate mechanism for improving core symptoms of ASD by artificial activation of DREADDs, as a simulation of OXT administration to activate OXTR+ neurons in the LS

Management of Natural History collections: criteria and parameters of evaluation

[ES] Las colecciones de historia natural son una herramienta básica para la investigación científica y el estudio de la distribución en el pasado de muchas especies, así como de la propia historia de la ciencia. Además del uso científico de estas colecciones, destacan otros como el histórico, el divulgativo-pedagógico y el estético. De ahí la importancia que tiene una gestión eficaz de las mismas, la cual implica diversos aspectos, que van desde la conservación y su mantenimiento, su inventario, ordenación y procesamiento informático hasta las múltiples tareas relacionadas con su uso en consultas, visitas, préstamos científicos y participación en actividades de carácter divulgativo. En este artículo se examinan los criterios para evaluar la gestión de las colecciones de historia natural y se definen una serie de parámetros, útiles para medir el estado de una colección y su evolución en el tiempo, tanto en su crecimiento como en su uso, principalmente. Se ejemplifica todo ello en el grupo de los poliquetos, del que el Museo Nacional de Ciencias Naturales de Madrid (MNCN) cuenta con una estimable colección, y se comparan los resultados, según varios parámetros seleccionados, con los de otras colecciones de poliquetos de diversas instituciones de todo el mundo.[EN] Natural History collections are a basic and essential tool for scientific research, the study of the distribution in the past of many species of animals and plants and the History of Science. As well as the scientific aspect of these collections, stand outs other uses as the historic one, the educational and the aesthetic. All these are reasons that show the importance of an effective management of the Natural History collections as well as the several tasks related to it, as consults, visits, scientific loans and educational activities. In this article various criteria and useful parameters are provided for evaluating the curatorial state of a Natural History collection and its evolution, both in growth and use mainly. Finally, an example based on the Polychaeta, an estimable group in the Invertebrates Collection of the Museo Nacional de Ciencias Naturales of Madrid (MNCN), is provided. The results of several selected parameters are compared with other Polychaeta collections from several institutions around the world.Peer reviewe

Increased In Vitro Intercellular Barrier Function of Lung Epithelial Cells Using Adipose-Derived Mesenchymal Stem/Stromal Cells

With the emergence of coronavirus disease-2019, researchers have gained interest in the therapeutic efficacy of mesenchymal stem/stromal cells (MSCs) in acute respiratory distress syndrome; however, the mechanisms of the therapeutic effects of MSCs are unclear. We have previously reported that adipose-derived MSCs (AD-MSCs) strengthen the barrier function of the pulmonary vessels in scaffold-based bioengineered rat lungs. In this study, we evaluated whether AD-MSCs could enhance the intercellular barrier function of lung epithelial cells in vitro using a transwell coculture system. Transepithelial electrical resistance (TEER) measurements revealed that the peak TEER value was significantly higher in the AD-MSC coculture group than in the AD-MSC non-coculture group. Similarly, the permeability coefficient was significantly decreased in the AD-MSC coculture group compared to that in the AD-MSC non-coculture group. Immunostaining of insert membranes showed that zonula occuldens-1 expression was significantly high at cell junctions in the AD-MSC coculture group. Moreover, cell junction-related gene profiling showed that the expression of some claudin genes, including claudin-4, was upregulated in the AD-MSC coculture group. Taken together, these results showed that AD-MSCs enhanced the barrier function between lung epithelial cells, suggesting that both direct adhesion and indirect paracrine effects strengthened the barrier function of lung alveolar epithelium in vitro

A case report of crystalline light chain inclusion-associated kidney disease affecting podocytes but without Fanconi syndrome

RATIONALE:Crystalline light chain inclusion-associated kidney disease affects mainly tubular epithelial cells and is often clinically manifested as Fanconi syndrome. However, only very few case reports about the crystalline deposits within the podocytes are available, and the nature of the pathogenic monoclonal light chain implicated in these cases is still unknown. We report a case of crystalline inclusion-associated kidney disease manifested as crystalline podocytopathy in which we identified the complete structure of the pathogenic monoclonal light chain as belonging to the germ-line gene of Vκ1-39.PATIENT CONCERNS:We describe a 65-year-old woman with crystalline light chain inclusion-associated kidney disease showing mild proteinuria and renal insufficiency with monoclonal gammopathy of undetermined significance without Fanconi syndrome. She had crystalline inclusions mainly within podocytes, tubular epithelial cells and histiocytes in the kidney. Light microscopy showed vacuolation of podocytes and tubular epithelial cells, while eosin negative pale needle-like crystals were present within these cells. Electron microscopy showed accumulation of club-like crystals with high electron density in podocytes, proximal tubular epithelial cells and interstitial histiocytes. Clonal analysis revealed that a pathogenic monoclonal light chain was derived from germline gene, Vκ1-39.DIAGNOSES:The diagnosis of crystalline light chain inclusion-associated kidney disease was made.INTERVENTIONS AND OUTCOMES:Bortezomib and dexamethasone were started and her renal function improved to eGFR 36 mL/min/1.73 m after 9 courses of therapy.LESSONS:Patients with light chain crystalline podocytopathy may have a similar pathogenic monoclonal light chain derived from the same germline gene, Vκ1-39, to that of patients with light chain proximal tubulopathy