Physiology and Pathophysiology of Human Airway Mucus

2022 ◽  
Author(s):  
David B. Hill ◽  
Brian Button ◽  
Michael Rubinstein ◽  
Richard C. Boucher
Keyword(s):  
Fluid Transport ◽  
Purinergic Signaling ◽  
Airflow Obstruction ◽  
Two Phase ◽  
Transport Pathways ◽  
Mucus Clearance ◽  
Hypoxic Conditions ◽  
Host Defense System ◽  
Osmotic Compression ◽  
Mucolytic Agents

The mucus clearance system is the dominant mechanical host defense system of the human lung. Mucus is cleared from the lung by cilia and airflow, including both two-phase gas liquid pumping and cough-dependent mechanisms, and mucus transport rates are heavily dependent on mucus concentration. Importantly, mucus transport rates are accurately predicted by the gel-on-brush model of the mucociliary apparatus from the relative osmotic moduli of the mucus and periciliary-glycocalyceal (PCL-G) layers. The fluid available to hydrate mucus is generated by transepithelial fluid transport. Feedback interactions between mucus concentrations and cilia beating, via purinergic signaling, coordinate Na+ absorptive vs Cl- secretory rates to maintain mucus hydration in health. In disease, mucus becomes hyperconcentrated (dehydrated). Multiple mechanisms derange the ion transport pathways that normally hydrate mucus in muco-obstructive lung diseases, e.g., CF, COPD, NCFB, and PCD. A key step in muco-obstructive disease pathogenesis is the osmotic compression of the mucus layer onto the airway surface with the formation of adherent mucus plaques and plugs, particularly in distal airways. Mucus plaques create locally hypoxic conditions and produce airflow obstruction, inflammation, infection, and, ultimately, airway wall damage. Therapies to clear adherent mucus with hydrating and mucolytic agents are rational, and strategies to develop these agents are reviewed.

Molecular Simulation Study of Oil-Water Two-Phase Fluid Transport in Shale Inorganic Nanopores

2021 ◽  
pp. 116948
Author(s):  
Wei Zhang ◽  
Qihong Feng ◽  
Zhehui Jin ◽  
Xiangdong Xing ◽  
Sen Wang
Keyword(s):  
Molecular Simulation ◽  
Simulation Study ◽  
Fluid Transport ◽  
Two Phase ◽  
Oil Water ◽  
Phase Fluid

scholarly journals Erythrocyte purinergic signaling components underlie hypoxia adaptation

2017 ◽  
Vol 123 (4) ◽  
pp. 951-956 ◽  
Author(s):  
Kaiqi Sun ◽  
Hong Liu ◽  
Anren Song ◽  
Jeanne M. Manalo ◽  
Angelo D’Alessandro ◽  
...  
Keyword(s):  
High Throughput Screening ◽  
Large Scale ◽  
Purinergic Signaling ◽  
New Technology ◽  
Hypoxic Conditions ◽  
Hypoxia Adaptation ◽  
Sphingosine 1 Phosphate ◽  
Amp Activated Protein Kinase ◽  
Signaling Components ◽  
Insight Into

Erythrocytes are vital to human adaptation under hypoxic conditions because of their abundance in number and irreplaceable function of delivering oxygen (O2). However, although multiple large-scale altitude studies investigating the overall coordination of the human body for hypoxia adaptation have been conducted, detailed research with a focus on erythrocytes was missing due to lack of proper techniques. The recently maturing metabolomics profiling technology appears to be the answer to this limitation. Metabolomics profiling provides unbiased high-throughput screening data that reveal the overall metabolic status of erythrocytes. Recent studies have exploited this new technology and provided novel insight into erythrocyte physiology and pathology. In particular, a series of studies focusing on erythrocyte purinergic signaling have reported that adenosine signaling, coupled with 5′ AMP-activated protein kinase (AMPK) and the production of erythrocyte-enriched bioactive signaling lipid sphingosine 1-phosphate, regulate erythrocyte glucose metabolism for more O2 delivery. Moreover, an adenosine-dependent “erythrocyte hypoxic memory” was discovered that provides an explanation for fast acclimation upon re-ascent. These findings not only shed new light on our understanding of erythrocyte function and hypoxia adaptation, but also offer a myriad of novel therapeutic possibilities to counteract various hypoxic conditions.

scholarly journals A Discrete Fracture Modeling Approach for Analysis of Coalbed Methane and Water Flow in a Fractured Coal Reservoir

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Tianran Ma ◽  
Hao Xu ◽  
Chaobin Guo ◽  
Xuehai Fu ◽  
Weiqun Liu ◽  
...  
Keyword(s):  
Water Flow ◽  
Coalbed Methane ◽  
Fluid Transport ◽  
Fracture Model ◽  
Phase Flow ◽  
Two Phase ◽  
Discrete Fracture Model ◽  
Discrete Fracture ◽  
Fractured Coal ◽  
Cbm Production

As a complex two-phase flow in naturally fractured coal formations, the prediction and analysis of CBM production remain challenging. This study presents a discrete fracture approach to modeling coalbed methane (CBM) and water flow in fractured coal reservoirs, particularly the influence of fracture orientation, fracture density, gravity, and fracture skeleton on fluid transport. The discrete fracture model is first verified by two water-flooding cases with multi- and single-fracture configurations. The verified model is then used to simulate CBM production from a discrete fractured reservoir using four different fracture patterns. The results indicate that fluid behavior is significantly affected by orientation, density, and fracture connectivity. Finally, several cases are performed to investigate the influence of gravity and fracture skeleton. The simulation results show that gas migrates upwards to the top reservoir during fluid extraction owing to buoyancy and the connected fracture skeleton plays a dominant role in fluid transport and methane production efficiency. Overall, the developed discrete fracture model provides a powerful tool to study two-phase flow in fractured coal reservoirs.

scholarly journals Effect of forced expirations on mucus clearance in patients with chronic airflow obstruction: effect of lung recoil pressure.

Thorax ◽  
1990 ◽  
Vol 45 (8) ◽  
pp. 623-627 ◽  
Author(s):  
C P van der Schans ◽  
D A Piers ◽  
H Beekhuis ◽  
G H Koeter ◽  
T W van der Mark ◽  
...  
Keyword(s):  
Airflow Obstruction ◽  
Recoil Pressure ◽  
Mucus Clearance

Active Hot Spot Cooling Controlled by Single-Sided Electrowetting-on-Dielectric (SEWOD)

2012 ◽  
Author(s):  
Sung-Yong Park ◽  
Jiangtao Cheng ◽  
Chung-Lung (C.-L. ) Chen
Keyword(s):  
Heat Transfer ◽  
Fluid Transport ◽  
Hot Spot ◽  
Two Phase ◽  
Electrowetting On Dielectric ◽  
Transfer Capability ◽  
Heat Transfer Capability ◽  
Spot Cooling ◽  
On Chip ◽  
Two Phase Cooling

Electrowetting-on-dielectric (EWOD) has attracted as one of the effective on-chip cooling technologies. It enables rapid transport of coolant droplets and heat transfer from target heat sources, while consuming extremely low power for fluid transport. However, a sandwiched configuration in conventional EWOD devices only allows sensible heat transfer, which very limits heat transfer capability of the device. In this paper, we report a novel single-sided EWOD (SEWOD) technology that enables two-phase cooling on a single-sided plate. As a result, heat transfer capability of the SEWOD device can be significantly enhanced. A complete set of droplet manipulation functions necessary for active hot spot cooling has been achieved on SEWOD. Hot spot surface modification to hydrophilic makes a droplet stick on a hot spot and maximize its contact area, greatly improving thermal rejection capability of the device. We have demonstrated two-phase cooling on SEWOD. With successive transportation of four droplets with a volume of 30 μL, the hot spot temperature that was initially heated up to 172°C was able to be stably maintained below 100 °C for 475s. This novel SEWOD-driven cooling technique promises to potentially function as a wickless vapor chamber with enhanced thermal managing capabilities.

scholarly journals Migration of Gas in Water Saturated Clays by Coupled Hydraulic-Mechanical Model

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-25 ◽  
Author(s):  
Aliaksei Pazdniakou ◽  
Magdalena Dymitrowska
Keyword(s):  
Mechanical Model ◽  
Fluid Transport ◽  
Two Phase Flow ◽  
Ion Beam ◽  
Damage Model ◽  
Phase Flow ◽  
Two Phase ◽  
Local Conditions ◽  
Small Pore ◽  
Water Saturated

Understanding the gas migration in highly water saturated sedimentary rock formations is of great importance for safety of radioactive waste repositories which may use these host rocks as barrier. Recent experiments on drainage in argillite samples have demonstrated that they cannot be represented in terms of standard two-phase flow Darcy model. It has been suggested that gas flows along highly localized dilatant pathways. Due to very small pore size and the opacity of the material, it is not possible to observe this two-phase flow directly. In order to better understand the gas transport, a numerical coupled hydraulic-mechanical model at the pore scale is proposed. The model is formulated in terms of Smoothed Particle Hydrodynamics (SPH) and is applied to simulate drainage within a sample reconstructed from the Focused Ion Beam (FIB) images of Callovo-Oxfordian claystone. A damage model is incorporated to take into account the degradation of elastic solid properties due to local conditions, which may lead to formation of new pathways and thus to modifications of fluid transport. The influence of the damage model as well as the possible importance of rigid inclusions is demonstrated and discussed.

Regulation of ion transport across lamprey (Lampetra fluviatilis) erythrocyte membrane by oxygen tension

1998 ◽  
Vol 201 (12) ◽  
pp. 1927-1937 ◽  
Author(s):  
LV Virkki ◽  
A Salama ◽  
M Nikinmaa
Keyword(s):  
Ion Transport ◽  
Erythrocyte Membrane ◽  
Oxygen Tension ◽  
Radioactive Isotope ◽  
Marked Reduction ◽  
Marked Effect ◽  
Hypotonic Medium ◽  
Lampetra Fluviatilis ◽  
Transport Pathways ◽  
Hypoxic Conditions

We have measured the effects of oxygen tension on the transport of Na+, K+ and Cl- across the erythrocyte membrane of the lamprey Lampetra fluviatilis. The transport of each ion was affected by the oxygen tension of the medium. Hypoxic conditions (PO2 2 kPa) caused an increase in the acidification-induced influx of Na+ via Na+/H+ exchange. The influx of K+ was only slightly affected by the oxygenation of the medium. In contrast, the basal K+ efflux, measured using the radioactive isotope 43K, was markedly reduced by decreasing the oxygen tension of the medium, whereas the K+ flux in hypotonic medium was not affected. Only minor effects of hypoxic conditions on the influx of Cl- were observed in either isotonic or hypotonic conditions (there was a tendency for the isotonic influx to increase) or on the efflux in isotonic conditions. However, deoxygenation caused a marked reduction in the Cl- efflux in hypotonic conditions. The results show that oxygen tension has a marked effect on the pH and volume regulatory transport pathways of lamprey erythrocytes. For K+ and Cl-, the regulation appears to be asymmetric, i.e. influx and efflux are affected differently.

scholarly journals Effects of hypoxia on alveolar fluid transport capacity in rat lungs

2001 ◽  
Vol 91 (4) ◽  
pp. 1766-1774 ◽  
Author(s):  
Tsutomu Sakuma ◽  
Mieko Hida ◽  
Yoshihiro Nambu ◽  
Kazuhiro Osanai ◽  
Hirohisa Toga ◽  
...  
Keyword(s):  
Fluid Transport ◽  
Serum Osmolality ◽  
Water Volume ◽  
Plasma Catecholamine ◽  
Transport Capacity ◽  
Alveolar Fluid Clearance ◽  
Lung Water ◽  
Alveolar Epithelial ◽  
Hypoxic Conditions ◽  
Plasma Catecholamine Concentrations

There is little information regarding the effect of hypoxia on alveolar fluid clearance capacity. We measured alveolar fluid clearance, lung water volume, plasma catecholamine concentrations, and serum osmolality in rats exposed to 10% oxygen for up to 120 h and explored the mechanisms responsible for the increase in alveolar fluid clearance. The principal results were 1) alveolar fluid clearance did not change for 48 h and then increased between 72 and 120 h of exposure to hypoxia; 2) although nutritional impairment during hypoxia decreased basal alveolar fluid clearance, endogenous norepinephrine increased net alveolar fluid clearance; 3) the changes of lung water volume and serum osmolality were not associated with those of alveolar fluid clearance; 4) an administration of β-adrenergic agonists further increased alveolar fluid clearance; and 5) alveolar fluid clearance returned to normal within 24 h of reoxygenation after hypoxia. In conclusion, alveolar epithelial fluid transport capacity increases in rats exposed to hypoxia. It is likely that a combination of endogenous norepinephrine and nutritional impairment regulates alveolar fluid clearance under hypoxic conditions.

Comparison of CFD and PIV Data for the Airflow in an Aero-Engine Bearing Chamber

2004 ◽  
Author(s):  
C. W. Lee ◽  
P. C. Palma ◽  
K. Simmons ◽  
S. J. Pickering
Keyword(s):  
Experimental Data ◽  
Fluid Transport ◽  
Cfd Simulation ◽  
Computational Modelling ◽  
Two Phase ◽  
Aero Engine ◽  
Flow Features ◽  
Airflow Field ◽  
Rsm Model ◽  
Engine Bearing

Investigations into the single-phase velocity field of a model aero-engine bearing chamber are presented. Adequately resolving the airflow field is important to subsequent computational modelling of two-phase fluid transport and heat transfer characteristics. A specially designed test rig, representing the features of a Rolls-Royce Trent series aero-engine bearing chamber, was constructed. Experimental data for the airflow field was obtained using particle image velocimetry (PIV). The results show a strong influence of shaft rotation and chamber geometry on the flow features within the bearing chamber. A computational fluid dynamics (CFD) simulation was carried out using the commercial CFD code FLUENT 6. Flow features were adequately modelled, showing the features of secondary velocities. Turbulence modelling using the differential Reynolds stress (RSM) model shows good agreement with the experimental data.

Performance Evaluation of a Pump-Assisted, Capillary Two-Phase Cooling Loop

2009 ◽  
Vol 1 (2) ◽  
Author(s):  
Chanwoo Park ◽  
Aparna Vallury ◽  
Jon Zuo
Keyword(s):  
Heat Input ◽  
Heat Load ◽  
Fluid Transport ◽  
Active Flow Control ◽  
Working Fluid ◽  
Heat Sources ◽  
Two Phase ◽  
Relative Level ◽  
Maximum Heat ◽  
Two Phase Cooling

A hybrid (pump-assisted and capillary) two-phase loop (HTPL) is experimentally investigated to characterize its thermal performance under stepwise heat input conditions. An integration of mechanical pumping with capillary pumping is achieved by using planar evaporator(s) and a two-loop design separating liquid and vapor flows. The evaporator(s) use a sintered copper grooved wick bonded with a liquid screen artery. No active flow control of the mechanical pumping is required because of the autonomous capillary pumping due to the self-adjusting liquid menisci to variable heat inputs of the evaporators. Unlike other active two-phase cooling systems using liquid spray and microchannels, the HTPL facilitates a passive phase separation of liquid from vapor in the evaporator using capillary action, which results in a lower flow resistance of the single-phase flows than two-phase mixed flows in fluid transport lines. In this work, a newly developed planar form-factor evaporator with a boiling heat transfer area of 135.3 cm2 is used aiming for the power electronics with large rectangular-shaped heat sources. This paper presents the experimental results of the HTPLs with a single evaporator handling a single heat source and dual evaporators handling two separate heat sources, while using distilled water as the working fluid for both cases. For the single evaporator system, the temperature results show that the HTPL does not create a big temperature upset under a stepwise heat load with sudden power increases and decreases. The evaporator thermal resistance is measured to be as low as 0.5 K cm2/W for the maximum heat load of 4.0 kW. A cold-start behavior characterized by a big temperature fluctuation was observed at the low heat inputs around 500 W. The HTPL with dual evaporators shows a strong interaction between the evaporators under an asymmetric heat load of the total maximum heat input of 6.5 kW, where each evaporator follows a different heat input schedule. The temperatures of the dual-evaporator system follow the profile of the total heat input, while the individual heat inputs determine the relative level of the temperatures of the evaporators.

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