Entamoeba histolytica: the dynamics of penetrating a meniscus

1982 ◽  
Vol 60 (9) ◽  
pp. 2124-2128 ◽  
Author(s):  
J. M. Smith ◽  
E. Meerovitch
Keyword(s):  
Surface Tension ◽  
Liquid Medium ◽  
Entamoeba Histolytica ◽  
Constant Pressure ◽  
Closed Circuit ◽  
Nitrogen Gas ◽  
Television System ◽  
Intercellular Movement ◽  
Resultant Forces ◽  
Histolytica Strain

Using a closed-circuit television system, Entamoeba histolytica strain IP-106 was observed to penetrate through a meniscus separating a medium–nitrogen gas interface. Both the forces exerted on the amoeba by the surface tension of the liquid medium and the resultant forces applied by the amoeba, at various stages during penetration, were calculated. During penetration the force applied increased to a maximum of 3.3 × 10−6 N. However it was found that the shape of the amoeba allowed it to penetrate with a constant pressure. Intercellular movement due to active pseudopodial motion may play an important role in the process of penetration.

Contact problem for wavy surfaces in the presence of an incompressible liquid and a gas in interface gaps

2018 ◽  
Vol 24 (11) ◽  
pp. 3381-3393 ◽  
Author(s):  
Oleh Kozachok ◽  
Rostyslav Martynyak
Keyword(s):  
Surface Tension ◽  
Contact Problem ◽  
Incompressible Liquid ◽  
Constant Pressure ◽  
Cauchy Kernel ◽  
Hilbert Kernel ◽  
Elastic Bodies ◽  
Laplace Formula ◽  
Interface Gaps ◽  
Wavy Surfaces

This paper presents a study on smooth elastic contact between two semi-infinite elastic bodies, one of which has a wavy surface, for the case when there are an incompressible liquid, not wetting the surfaces of the bodies, at the central region of each interface gap and a gas under constant pressure at the edges of each gap. Due to the surface tension of the liquid, a pressure drop occurs in the liquid and the gas, which is described by the Laplace formula. The formulated contact problem is reduced to a singular integral equation (SIE) with the Hilbert kernel, which is transformed into a SIE with the Cauchy kernel for a derivative of a height of the gaps. A system of transcendental equations for a width of each gap and a width of the gap region filled with the liquid is obtained from the condition of boundedness of the contact stresses at the gap ends and the condition of liquid amount conservation. It is solved numerically, and the dependences of the width and shape of the gaps, the width of the gap regions filled with the liquid and the contact approach of the bodies on the applied load and the surface tension of the liquid are analyzed.

THE MECHANISM OF PACEMAKER ACCELERATION DUE TO INCREASED INTRA-ATRIAL PRESSURE IN THE ISOLATED ATRIUM

1962 ◽  
Vol 40 (6) ◽  
pp. 805-814 ◽  
Author(s):  
G. W. Mainwood
Keyword(s):  
Constant Pressure ◽  
Pressure Response ◽  
Ph Gradient ◽  
Atrial Pressure ◽  
Closed Circuit ◽  
Atrial Wall ◽  
Bicarbonate Concentration ◽  
Rat Atria ◽  
Increased Pressure ◽  
Isolated Rat

A closed circuit with a miniature pump was used to perfuse isolated rat atria through the lumen. The rate of spontaneous atrial potentials was measured continuously on a recording potentiometer.The response of the atrium to changes in luminal pressure was observed under a number of different conditions. The acceleration due to increased pressure was greatest when the perfusing fluid contained low bicarbonate concentrations (5–10 mmolar) and was very much reduced or abolished with 28 mmolar bicarbonate. Pacemaker rate at constant pressure varies directly with pH in the presence of high bicarbonate concentrations. The pressure response may be interpreted in terms of a pH gradient across the atrial wall which is dependent on the bicarbonate concentration and may be reduced by stretching the atrium.

Closed-Circuit Television System for X-Ray Inspection

1962 ◽  
Vol 71 (6) ◽  
pp. 444-447 ◽  
Author(s):  
Jay P. Mitchell ◽  
Merle L. Rhoten
Keyword(s):  
Closed Circuit ◽  
Television System ◽  
Closed Circuit Television ◽  
X Ray

scholarly journals Dynamics of Thin Film Under a Volatile Solvent Source Driven by a Constant Pressure Gradient Flow

Fluids ◽  
2019 ◽  
Vol 4 (4) ◽  
pp. 198
Author(s):  
Mohammad Irshad Khodabocus ◽  
Mathieu Sellier ◽  
Volker Nock
Keyword(s):  
Thin Film ◽  
Surface Tension ◽  
Free Surface ◽  
Evolution Equation ◽  
Constant Pressure ◽  
Thin Liquid Film ◽  
Gradient Flow ◽  
Surface Tension Gradient ◽  
Nonlinear Parabolic ◽  
Induced Flow

The evolution of a thin liquid film subject to a volatile solvent source and an air-blow effect which modifies locally the surface tension and leads to Marangoni-induced flow is shown to be governed by a degenerate fourth order nonlinear parabolic h-evolution equation of the type given by ∂ t h = − div x M 1 h ∂ x 3 h + M 2 h ∂ x h + M 3 h , where the mobility terms M 1 h and M 2 h result from the presence of the source and M 3 h results from the air-blow effect. Various authors assume M 2 h ≈ 0 and exclude the air-blow effect into M 3 h . In this paper, the authors show that such assumption is not necessarily correct, and the inclusion of such effect does disturb the dynamics of the thin film. These emphasize the importance of the full definition t → · grad γ = grad x γ + ∂ x h grad y γ of the surface tension gradient at the free surface in contrast to the truncated expression t → · grad γ ≈ grad x γ employed by those authors and the effect of the air-blow flowing over the surface.

Visual Rehabilitation within an Interdisciplinary Low-Vision Centre—A Pilot Project

1981 ◽  
Vol 75 (1) ◽  
pp. 28-32
Author(s):  
Gene Stollman ◽  
Nurit Neustadt-noy
Keyword(s):  
Low Vision ◽  
Pilot Project ◽  
Clinical Staff ◽  
Closed Circuit ◽  
Visual Rehabilitation ◽  
Television System ◽  
Impaired Vision ◽  
Closed Circuit Television ◽  
Reading And Writing ◽  
Vision Rehabilitation

Describes an attempt to improve reading and writing capability of children with severely impaired vision, using a Closed-Circuit Television System, under the supervision of members of clinical staff of the Jerusalem Centre for Counseling and Vision Rehabilitation of Children, and an orientation & mobility instructor.

scholarly journals A Biomimetic Approach to Increasing Soft Actuator Performance by Friction Reduction

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1120
Author(s):  
Nguyen Quang Khuyen ◽  
Rudolf Kiefer ◽  
Fred Elhi ◽  
Gholamreza Anbarjafari ◽  
Jose G. Martinez ◽  
...  
Keyword(s):  
Surface Tension ◽  
Liquid Medium ◽  
Friction Reduction ◽  
Forward Solution ◽  
Soft Actuator ◽  
Power Increase ◽  
Tetramethylammonium Chloride ◽  
Actuator System ◽  
Biomimetic Approach ◽  
System Operating

While increasing power output is the most straight-forward solution for faster and stronger motion in technology, sports, or elsewhere, efficiency is what separates the best from the rest. In nature, where the possibilities of power increase are limited, efficiency of motion is particularly important; the same principle can be applied to the emerging biomimetic and bio-interacting technologies. In this work, by applying hints from nature, we consider possible approaches of increasing the efficiency of motion through liquid medium of bilayer ionic electroactive polymer actuations, focusing on the reduction of friction by means of surface tension and hydrophobicity. Conducting polyethylene terephthalate (PET) bilayers were chosen as the model actuator system. The actuation medium consisted of aqueous solutions containing tetramethylammonium chloride and sodium dodecylbenzenesulfonate in different ratios. The roles of ion concentrations and the surface tension are discussed. Hydrophobicity of the PET support layer was further tuned by adding a spin-coated silicone layer to it. As expected, both approaches increased the displacement—the best results having been obtained by combining both, nearly doubling the bending displacement. The simple approaches for greatly increasing actuation motion efficiency can be used in any actuator system operating in a liquid medium.

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