Search results for "Helium"

Theoretical Studies of the Propagation of Sound in Channels Filled with Helium II

1974

The two-fluid nature of liquid helium II leads to the possibility of several types of wave motion, e.g., first sound, second sound, fourth sound, and the fifth wave mode. First and second sound appear in the bulk liquid. The characters of these wave modes alter materially if helium is bounded by solid walls, e.g., between two plane-parallel plates forming a channel. This paper reports upon the calculation of the properties of wave modes which can exist in such channels.

MEASUREMENTS OF THE ATTENUATION OF FOURTH SOUND IN HELIUM II

1978

Waves Propagation in Superfluid Helium in Presence of Combined Rotation and Counterflow

2008

Using the linear macroscopic mono-fluid model of liquid helium II, in which the fundamental fields are the density ?, the velocity v, the temperature T and heat flux q and taking into account the expression of an additional pressure tensor P(w), introduced to describe phenomena linked to vortices, a complete study of wave propagation is made in the complex situation involving thermal counterflow in a rotating cylinder.

Establishment of a pulmonary epithelial barrier on biodegradable poly-L-lactic-acid membranes

2019

Development of biocompatible and functional scaffolds for tissue engineering is a major challenge, especially for development of polarised epithelia that are critical structures in tissue homeostasis. Different in vitro models of the lung epithelial barrier have been characterized using non-degradable polyethylene terephthalate membranes which limits their uses for tissue engineering. Although poly-L-lactic acid (PLLA) membranes are biodegradable, those prepared via conventional Diffusion Induced Phase Separation (DIPS) lack open-porous geometry and show limited permeability compromising their use for epithelial barrier studies. Here we used PLLA membranes prepared via a modification of the…

Explaining the phenomenon of nitrate tolerance.

2005

During the last century, nitroglycerin has been the most commonly used antiischemic and antianginal agent. Unfortunately, after continuous application, its therapeutic efficacy rapidly vanishes. Neurohormonal activation of vasoconstrictor signals and intravascular volume expansion constitute early counter-regulatory responses (pseudotolerance), whereas long-term treatment induces intrinsic vascular changes, eg, a loss of nitrovasodilator-responsiveness (vascular tolerance). This is caused by increased vascular superoxide production and a supersensitivity to vasoconstrictors secondary to a tonic activation of protein kinase C. NADPH oxidase(s) and uncoupled endothelial nitric oxide synthase …

Anti-inflammatory effects of sicilian pistachio (pistacia vera l.) Nut in an in vitro model of human intestinal epithelium

2015

Intestinal epithelial cells play an important role in the mucosal inflammatory response. These cells synthesize and secrete inflammatory mediators, and selectively modulate the permeability of the epithelial monolayer thus exposing immune cells to antigens. Although intestinal inflammatory response is crucial to maintain gut structural integrity and function, alteration and dysregulation of inflammatory pathways contribute to tissue damage and ulceration, and are thought to be pivotal factors in the pathogenesis of different inflammatory gut diseases [1]. The limited efficacy of conventional pharmacological therapy in the intestinal inflammatory conditions has fostered research on alternati…

Anti-inflamamtory effects of Sicilian pistachio (Pistacia vera L.) nut in an in vitro model of human intestinal epithelium

2013

Contribution of sinusoidal endothelial liver cells to liver fibrosis: expression of transforming growth factor-beta 1 receptors and modulation of pla…

1993

Transforming growth factor-beta 1 is an important cytokine in the pathophysiology of liver fibrosis, stimulating the production of extracellular matrix. Whether this cytokine can also control the degradation of matrix proteins in liver cells has not been investigated. Because plasmin is an important protease for the degradation of matrix glycoproteins, we investigated whether sinusoidal endothelial liver cells could contribute to fibrosing liver disease through the modulation of plasmin-generating enzymes in response to transforming growth factor-beta 1. Sinusoidal endothelial cells from guinea pig liver were investigated in pure monolayer culture. Using 125I-labelled transforming growth fa…

The Innervation of Taste Buds in the Soft Palate of the Rat as Revealed by Methylene Blue Staining.

1996

Light microscopic data on the innervation of taste buds in the soft palate of the rat obtained by methylene blue (MB) supravital staining are presented here for the first time. The taste pore including subpopulations of taste bud cells and nerve fibers were stained. Intragemmal nerve fibers were detected ascending up to the taste pore; this suggests the possibility of additional paracellular pathways in taste transduction directly via nerve fibers. Moreover, relatively large bulbous or laminar enlargements of the intragemmal nerve fibers were found. The branches of these nerve fibers, showing minute spiny protuberances, appeared to anastomose. Some perigemmal nerve fibers were also seen in …

Study of the High-Frequency Inductive Coupled Discharge Plasma Interaction with Walls

2007

The high-frequency electrodeless light sources (HFELS) are widely used as bright radiators of narrow and intense spectral lines covering the region from VUV to IR. Special HFELS filled with pure helium at pressures from 0.2 to 5 Torr were prepared for diagnostics of interaction between the filling element and the wall material (glass). Pollution of the discharge plasma with the oxygen admixture was studied by spectroscopy. Atomic force microscopy experiments were performed to find modification of the wall surface at the nanoscale level. Release of oxygen by the walls is found to depend strongly on the discharge conditions and significant changes of the surface structure are detected after p…