Constant-angle surfaces in liquid crystals

We discuss some properties of surfaces in R3 whose unit normal has constant angle with an assigned direction field. The constant angle condition can be rewritten as an Hamilton-Jacobi equation correlating the surface and the direction field. We focus on examples motivated by the physics of interfaces in liquid crystals and of layered fluids, and discuss the properties of the constant-angle surfaces when the direction field is singular along a line (disclination) or at a point (hedgehog defect

Effects of oxygen partial pressure and annealing temperature on the formation of sputtered tungsten oxide films

Thin films of tungsten oxide were deposited on silicon substrates using reactive radio frequency sputtering. The structure of the films strongly depends on the conditions of deposition and post-treatment. Important issues are the influences of oxygen pressure during deposition and annealing temperature on the morphology. Atomic force microscopy and scanning electron microscopy revealed that films were formed by grains. The sample deposited with an Ar:O(2) partial pressure ratio of 1: 1 showed the highest roughness and the smallest grains when annealed at 350degrees C. X-ray photoelectron spectroscopy analysis revealed that the films were close to their stoichiometric formulation irrespective of the oxygen partial pressure used during film deposition. The number of W=O bonds at the grain boundaries was found to be dependent on the oxygen partial pressure. Analysis by Raman spectroscopy suggested that the structure of the films was monoclinic. On the basis of these results, an annealing temperature of 350degrees C was selected as post-treatment for the fabrication of WO(3) gas sensors. These sensors were highly sensitive, highly selective to ammonia vapors, and moderately responsive to humidity. (C) 2002 The Electrochemical Society.1493H81H8

Diffusion of Chemically Reacting Fluids through Nonlinear Elastic Solids and 1D Stabilized Solutions

This paper summarizes a 1D adaptation (Hall et al., Math Mech Solids, 2014) of the reactive fluid–solid mixture theory of Hall and Rajagopal (Math Mech Solids 17(2):131–164, 2012), which considers an anisotropic viscous fluid diffusing and chemically reacting with an anisotropic elastic solid. The present implementation introduces a stabilized mixed finite element method for advection–diffusion–reaction phenomena, which is applied to 1D isothermal problems involving Fickian diffusion, oxidation of PMR-15 polyimide resin, and slurry infiltration. The energy and entropy production relations are captured via a Lagrange multiplier that results from imposing the constraint of maximum rate of entropy production, reducing the primary PDEs to the balance equations of mass and linear momentum for the fluid and the solid, together with an equation for the Lagrange multiplier. The Fickian diffusion application considers a hyperbolic first order system with a boundary discontinuity and stable approach to the usual parabolic model. Results of the oxidation modeling of Tandon et al. (Polym Degrad Stab 91(8):1861–1869, 2006) are recovered by employing the reaction kinetics model and properties assumed there, while providing in addition the individual constituent kinematic and kinetic behaviors, thus adding rich interpretive detail in comparison to the original treatment (Tandon et al., Polym Degrad Stab 91 (8):1861–1869, 2006); two adjustable parameters describing coupled chemomechanical and purely chemical dissipation are added. The slurry infiltration application simulates the imposed mass deposition process and consequent effects on the kinematic and kinetic behaviors of the constituents.Ope

Hyposalivation but not Sjögren’s syndrome associated with microbial dysbiosis in women

BackgroundSaliva modulates the environment of the oral biofilm through pH buffer, microbial attachment to host surfaces, and nutritional source. The ecology of stress occurs when a physical factor adversely impacts an ecosystem or its biotic components. Therefore, reduced salivary flow can affect oral-host balance. The leading causes of hyposalivation include disease-associated Sjögren’s syndrome (SS) and menopausal women as aging-associated. However, little is known about the oral microbiome integrated with sex hormones in hyposalivation. This study aimed to characterize the hyposalivation microbiome caused by aging or disease affecting the salivary glands in women.MethodsWe included 50 women older than 40 years of age in any menopausal phase. We collected stimulated saliva from 25 women diagnosed with SS (SS) and 25 without SS (non-SS). The bacterial profile of the patients was obtained by 16S rRNA sequencing. Bioinformatics analysis used machine learning to analyze the cohort’s signs, symptoms, and bacterial profile. Salivary estradiol as a sex hormone variation level was determined.ResultsWe obtained that 79% of the SS group, and 52% of the non-SS group had hyposalivation. We found a negatively correlated Prevotella-age and Rothia-estradiol in the SS group. Highlight, we found that the cause of the hyposalivation in the study did not explain differences in microbial diversity comparing non-SS and SS groups. Therefore, microbial communities found in hyposalivation but not related to systemic conditions suggest that changes in the oral environment might underpin host-microbial balance.ConclusionThe salivary microbiome was similar in women with and without SS. However, hyposalivation showed two distinctive clusters associated with the bacterial population profiles. Our study suggests that local ecological disturbances could drive the change in the microbiome

Liquid crystals and their defects

These lecture notes discuss classical models of liquid crystals, and the different ways in which defects are described according to the different models.Comment: CIME lecture course, Cetraro, 201

The Network Zoo: a multilingual package for the inference and analysis of gene regulatory networks

Inference and analysis of gene regulatory networks (GRNs) require software that integrates multi-omic data from various sources. The Network Zoo (netZoo; netzoo.github.io) is a collection of open-source methods to infer GRNs, conduct differential network analyses, estimate community structure, and explore the transitions between biological states. The netZoo builds on our ongoing development of network methods, harmonizing the implementations in various computing languages and between methods to allow better integration of these tools into analytical pipelines. We demonstrate the utility using multi-omic data from the Cancer Cell Line Encyclopedia. We will continue to expand the netZoo to incorporate additional methods

A theoretical modeling framework for motile and colonial harmful algae

Abstract Climate change is leading to an increase in severity, frequency, and distribution of harmful algal blooms across the globe. For many harmful algae species in eutrophic lakes, the formation of such blooms is controlled by three factors: the lake hydrodynamics, the vertical motility of the algae organisms, and the ability of the organisms to form colonies. Here, using the common cyanobacterium Microcystis aeruginosa as an example, we develop a model that accounts for both vertical transport and colony dynamics. At the core of this treatment is a model for aggregation. For this, we used Smoluchowski dynamics containing parameters related to Brownian motion, turbulent shear, differential setting, and cell‐to‐cell adhesion. To arrive at a complete description of bloom formation, we place the Smoluchowski treatment as a reaction term in a set of one‐dimensional advection‐diffusion equations, which account for the vertical motion of the algal cells through molecular and turbulent diffusion and self‐regulating buoyant motion. Results indicate that Smoluchowski aggregation qualitatively describes the colony dynamics of M. aeruginosa. Further, the model demonstrates wind‐induced mixing is the dominant aggregation process, and the rate of aggregation is inversely proportional to algal concentration. Because blooms of Microcystis typically consist of large colonies, both of these findings have direct consequences to harmful algal bloom formation. While the theoretical framework outlined in this manuscript was derived for M. aeruginosa, both motility and colony formation are common among bloom‐forming algae. As such, this coupling of vertical transport and colony dynamics is a useful step for improving forecasts of surface harmful algal blooms

The role of oxygen partial pressure and annealing temperature on the formation of W=O bonds in thin WO3 films

Thin films of tungsten oxide were deposited onto silicon substrates using reactive rf sputtering. The structure of the films is strongly dependent on the conditions of deposition and post-treatment. Important issues are the influences of oxygen pressure during deposition and of annealing temperature. We used x-ray photoelectron spectroscopy to investigate the in-depth composition of the films. The most surface sensitive O 1s core level spectra are made up of two structures, one generated by photoelectrons emitted from oxygen atoms in WO3 (O-W-O) and other at lower energy generated by the photoelectrons emitted from oxygen atoms located at the boundary of the grains (W=O). Using Raman spectroscopy, an increase of the W=O/O-W-O ratio was correlated to an increase in the oxygen partial pressure used during the deposition. A decrease of this ratio was observed while annealing temperature was increased, which was correlated to an increase in the size of the grains that form the films.17652252