Search results for "pillar"
showing 10 items of 877 documents
Vascular Microarchitecture of Murine Colitis-Associated Lymphoid Angiogenesis
2009
In permissive tissues, such as the gut and synovium, chronic inflammation can result in the ectopic development of anatomic structures that resemble lymph nodes. These inflammation-induced structures, termed lymphoid neogenesis or tertiary lymphoid organs, may reflect differential stromal responsiveness to the process of lymphoid neogenesis. To investigate the structural reorganization of the microcirculation involved in colonic lymphoid neogenesis, we studied a murine model of dextran sodium sulfate (DSS)-induced colitis. Standard 2-dimensional histology demonstrated both submucosal and intramucosal lymphoid structures in DSS-induced colitis. A spatial frequency analysis of serial histolog…
Early prediction of coma recovery after cardiac arrest with blinded pupillometry
2017
Objectives Prognostication studies on comatose cardiac arrest (CA) patients are limited by lack of blinding, potentially causing overestimation of outcome predictors and self-fulfilling prophecy. Using a blinded approach, we analysed the value of quantitative automated pupillometry to predict neurological recovery after CA. Methods We examined a prospective cohort of 103 comatose adult patients who were unconscious 48 hours after CA and underwent repeated measurements of quantitative pupillary light reflex (PLR) using the Neurolight-Algiscan® device. Clinical examination, electroencephalography (EEG), somatosensory evoked potentials (SSEP) and serum neuron specific enolase (NSE) were perfor…
Macroscopic equations of motion for two-phase flow in porous media
1998
The established macroscopic equations of motion for two phase immiscible displacement in porous media are known to be physically incomplete because they do not contain the surface tension and surface areas governing capillary phenomena. Therefore a more general system of macroscopic equations is derived here which incorporates the spatiotemporal variation of interfacial energies. These equations are based on the theory of mixtures in macroscopic continuum mechanics. They include wetting phenomena through surface tensions instead of the traditional use of capillary pressure functions. Relative permeabilities can be identified in this approach which exhibit a complex dependence on the state v…
Fluctuating Interfaces in Liquid Crystals
2008
We review and compare recent work on the properties of fluctuating interfaces between nematic and isotropic liquid-crystalline phases. Molecular dynamics and Monte Carlo simulations have been carried out for systems of ellipsoids and hard rods with aspect ratio 15:1, and the fluctuation spectrum of interface positions (the capillary wave spectrum) has been analyzed. In addition, the capillary wave spectrum has been calculated analytically within the Landau-de Gennes theory. The theory predicts that the interfacial fluctuations can be described in terms of a wave vector dependent interfacial tension, which is anisotropic at small wavelengths (stiff director regime) and becomes isotropic at l…
Theoretical and Experimental Studies of Capillary Hysteresis in MCM-41
1996
Mesoporous materials of MCM-41 type are considered to be reference model adsorbents due to their regular pore structure. Nitrogen adsorption isotherms on MCM-41 are modeled using the Non-Local Density Functional Theory (NLDFT). The thermal dependence of the thermodynamic hysteresis predicted by the NLDFT is confirmed by experimental measurements. The nitrogen hysteresis on MCM-41 at temperatures below 77.4 K or in pores greater than 4 nm is associated with the metastability of the adsorption branch of the isotherm. In the hysteresis regime, the desorption branch is likely to be thermodynamically stable and is recommended for calculating pore size distributions.
Colloid-polymer mixtures between asymmetric walls: Evidence for an interface localization transition
2007
We demonstrate via computer simulation that mixtures of colloids and polymers confined to thin films have the ability to undergo an interface localization transition. While one wall of the film is assumed to be hard for both particles, at the other wall, an additional repulsive potential acts, but on the colloids only. By varying the strength of this repulsion, a crossover from capillary condensation to interface localization is found. The latter occurs under conditions where in the bulk almost complete phase separation has occurred.
Direct measurement of forces between particles and bubbles
1999
One of the elementary stages of the flotation process is the formation of an aggregate between the particle and a bubble. This aggregate formation is governed by hydrodynamic, capillary and interparticle forces. During the last four years, techniques have been developed to measure directly the force between a colloidal particle and a bubble. These techniques are closely related to the development of atomic force microscopy. Advantages and possibilities, as well as limits and drawbacks are described.
Symmetric diblock copolymers confined into thin films: A Monte Carlo investigation on the CRAY T3E
2000
We present the results of large scale computer simulations targeted at investigating the phase stability and the structure of symmetric AB diblock copolymers in thin films. The connectivity of the two different monomer species A and B in the diblock copolymer prevents macrophage separation and the molecules assemble into A-rich and B-rich domains on the scale of the molecule’s extension. This large length scale of the ordering phenomena makes these polymeric systems a promising candidate for revealing the universal features of self-assembling in amphiphilic molecules. However, the widely spread length and time scales impart protracted long relaxation times to the systems and pose a challeng…
ChemInform Abstract: Tuning the Defect Configurations in Nematic and Smectic Liquid Crystalline Shells
2013
Thin liquid crystalline shells surrounding and surrounded by aqueous phases can be conveniently produced using a nested capillary microfluidic system, as was first demonstrated by Fernandez-Nieves et al. in 2007. By choosing particular combinations of stabilizers in the internal and external phases, different types of alignment, uniform or hybrid, can be ensured within the shell. Here, we investigate shells in the nematic and smectic phases under varying boundary conditions, focusing in particular on textural transformations during phase transitions, on the interaction between topological defects in the director field and inclusions in the liquid crystal (LC), and on the possibility to relo…
Trapping and mobilization of residual fluid during capillary desaturation in porous media
1998
We discuss the problem of trapping and mobilization of nonwetting fluids during immiscible two-phase displacement processes in porous media. Capillary desaturation curves give residual saturations as a function of capillary number. Interpreting capillary numbers as the ratio of viscous to capillary forces the breakpoint in experimental curves contradicts the theoretically predicted force balance. We show that replotting the data against a novel macroscopic capillary number resolves the problem for discontinuous mode displacement.