scholarly journals Liquid transport produced by a cluster of peristaltic contractions in a circular channel

2021 ◽  
Vol 6 (9) ◽  
Author(s):  
Tomoki Oyama ◽  
Shunichi Ishida ◽  
Kohei Maeyama ◽  
Taimei Miyagawa ◽  
Yohsuke Imai
Keyword(s):  
Circular Channel ◽  
Liquid Transport ◽  
Peristaltic Contractions

Fast Water Transport Through Sub-5 nm Polyamide Nanofilms: The New Upper-Bound of the Permeance-Selectivity Trade-Off in Nanofiltration

2021 ◽  
Author(s):  
Pulak Sarkar ◽  
Solagna Modak ◽  
Santanu Ray ◽  
Vasista Adupa ◽  
K. Anki Reddy ◽  
...  
Keyword(s):  
Water Transport ◽  
Composite Membrane ◽  
Upper Bound ◽  
Polymer Membranes ◽  
Liquid Transport ◽  
Trade Off ◽  
Commercial Exploitation

Liquid transport through the composite membrane is inversely proportional to the thickness of its separation layer. While the scalable fabrication of ultrathin polymer membranes is sought for their commercial exploitation,...

scholarly journals A methodology for hygrothermal modelling of imperfect masonry interfaces

2021 ◽  
pp. 174425912198938
Author(s):  
Michael Gutland ◽  
Scott Bucking ◽  
Mario Santana Quintero
Keyword(s):  
Boundary Conditions ◽  
Material Properties ◽  
Structural Integrity ◽  
Bulk Material ◽  
Weather Conditions ◽  
Masonry Wall ◽  
Two Dimensional ◽  
Liquid Transport ◽  
Imperfect Contact ◽  
Moisture Contents

Hygrothermal models are important tools for assessing the risk of moisture-related decay mechanisms which can compromise structural integrity, loss of architectural features and material. There are several sources of uncertainty when modelling masonry, related to material properties, boundary conditions, quality of construction and two-dimensional interactions between mortar and unit. This paper examines the uncertainty at the mortar-unit interface with imperfections such as hairline cracks or imperfect contact conditions. These imperfections will alter the rate of liquid transport into and out of the wall and impede the liquid transport between mortar and masonry unit. This means that the effective liquid transport of the wall system will be different then if only properties of the bulk material were modelled. A detailed methodology for modelling this interface as a fracture is presented including definition of material properties for the fracture. The modelling methodology considers the combined effect of both the interface resistance across the mortar-unit interface and increase liquid transport in parallel to the interface, and is generalisable to various combinations of materials, geometries and fracture apertures. Two-dimensional DELPHIN models of a clay brick/cement-mortar masonry wall were created to simulate this interaction. The models were exposed to different boundary conditions to simulate wetting, drying and natural cyclic weather conditions. The results of these simulations were compared to a baseline model where the fracture model was not included. The presence of fractures increased the rate of absorption in the wetting phase and an increased rate of desorption in the drying phase. Under cyclic conditions, the result was higher peak moisture contents after rain events compared to baseline and lower moisture contents after long periods of drying. This demonstrated that detailed modelling of imperfections at the mortar-unit interface can have a definitive influence on results and conclusions from hygrothermal simulations.

Discussion of “Brink Depth for a Circular Channel”

1963 ◽  
Vol 89 (3) ◽  
pp. 389-405
Author(s):  
R. M. Advani ◽  
Praxitelis A. Argyropoulos ◽  
N. Rajaratnam ◽  
D. Muralidhar ◽  
John K. Vennard
Keyword(s):  
Circular Channel ◽  
Brink Depth

Peristaltic Contractions Help Snaring During Underwater EMR of Colonic Non-Granular Pseudodepressed LST

2021 ◽  
Author(s):  
H Uchima ◽  
J Colán-Hernández ◽  
I Marín ◽  
R Temiño ◽  
A Mata ◽  
...  
Keyword(s):  
Peristaltic Contractions

scholarly journals WATER INGESTION DYNAMICS IN PATIENTS WITH ACHALASIA: INFLUENCE OF SEX AND AGE

2018 ◽  
Vol 55 (suppl 1) ◽  
pp. 25-29 ◽  
Author(s):  
Roberto Oliveira DANTAS ◽  
Rachel Aguiar CASSIANI ◽  
Carla Manfredi SANTOS ◽  
Leda Maria Tavares ALVES
Keyword(s):  
Healthy Volunteers ◽  
Chagas Disease ◽  
Ingestion Rate ◽  
Control Group ◽  
Bolus Transit ◽  
Water Ingestion ◽  
Lower Volume ◽  
Drinking Test ◽  
Severity Of The Disease ◽  
Peristaltic Contractions

ABSTRACT BACKGROUND: Achalasia is a disease that affects esophageal bolus transit due to the absence of esophageal peristaltic contractions and impaired or absent relaxation of the lower esophageal sphincter. OBJECTIVE: The objective of this investigation was: a) to evaluate the dynamics of water ingestion in patients with achalasia, idiopathic or caused by Chagas’ disease; b) to evaluate the influence of sex and age on water ingestion dynamics. METHODS: The investigation was conducted with 79 patients with achalasia (27 idiopathic and 52 Chagas’ disease) and 91 healthy volunteers, all evaluated by the water-drinking test. The individuals drank, in triplicate, 50 mL of water without interruption. The time and the number of swallows for this task were counted. We also measured: (a) inter-swallow interval - the time to complete the task, divided by the number of swallows during the task; (b) swallowing rate - volume drunk divided by the time; (c) volume per swallow - volume drunk divided by the number of swallows. RESULTS: Patients with achalasia took longer to ingest all the volume (mean 12.2 seconds) than healthy controls (mean 5.4 seconds), had greater number of swallows, longer interval between swallows, lower swallowing rate (5.2 mL/s vs 10.9 mL/s in controls) and lower volume per swallow (9.1 mL vs 14.4 mL in controls, P<0.01). Among healthy volunteers, women had a shorter interval between swallows and lower volume per swallow compared with men, and in the achalasia group, women had a longer interval between swallows and lower ingestion rate. No difference in the drinking test results was found between younger and older subjects in achalasia or control group. Also, no differences were observed between patients with Chagas’ disease and those with idiopathic achalasia, or between patients with increased and normal esophageal diameter. CONCLUSION: Patients with achalasia have difficulty in ingesting water, taking a longer time to complete the task, which is influenced by sex but not by age or severity of the disease.

In vivo and in vitro influence of human recombinant hemoglobin on esophageal function

1995 ◽  
Vol 268 (3) ◽  
pp. G443-G450 ◽  
Author(s):  
S. Chakder ◽  
G. J. Rosenthal ◽  
S. Rattan
Keyword(s):  
Oxygen Carrier ◽  
Electrical Field Stimulation ◽  
Esophageal Peristalsis ◽  
Esophageal Function ◽  
Significant Impairment ◽  
Esophageal Sphincter ◽  
Peristaltic Contractions

The purpose of the present investigation was to examine the influence of a nitric oxide scavenger, hemoglobin (Hb), on esophageal function. Intraluminal pressures of anesthetized opossums were recorded from lower esophageal sphincter (LES) and 1, 5, and 9 cm above the LES. The influence of a representative Hb-based oxygen carrier was examined on swallowing-induced esophageal peristalsis and LES relaxation. In in vitro studies, LES relaxation and esophageal peristaltic contractions were induced by the activation of nonadrenergic noncholinergic (NANC) neurons by electrical field stimulation (EFS). Hb caused significant impairment in swallowing- and EFS-induced LES relaxation and a significant increase in the speed of esophageal peristalsis. In some experiments, swallowing caused simultaneous contractions in the esophagus following Hb administration. Although Hb completely blocked LES relaxation by NO and significantly attenuated that by NANC nerve stimulation, it had no significant effect on isoproterenol-induced LES relaxations. The data support the role of NO in LES relaxation and esophageal peristalsis. This esophageal model may be important in understanding the influence of NO inhibitors and scavengers in gastrointestinal motility.

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