Transport Phenomena in Smectite Clay Explained by Considering Microstructural Features

1997 ◽  
Vol 506 ◽  
Author(s):  
Roland Pusch
Keyword(s):  
Hydraulic Conductivity ◽  
High Flow ◽  
Diffusive Transport ◽  
Transport Capacity ◽  
Microstructural Parameter ◽  
Flow Capacity ◽  
Natural Clays ◽  
Microstructural Data ◽  
Microstructural Homogeneity ◽  
Diffusive Capacity

ABSTRACTThe microstructure of clays controls their transport properties. This is concluded from comparing microstructural parameter data with the hydraulic conductivity and the ion diffusive transport capacity. Illitic clays contain a number of interacting open voids with a high flow capacity while natural smectite-rich clays are more homogeneous with smaller voids and a lower hydraulic conductivity than illitic clays with the same density. Artificially prepared smectitic clays, like those proposed for embedding canisters with highly radioactive waste, have a higher conductivity than natural clays with the same smectite content because the microstructural homogeneity of the artificial clays is less good.The anion diffusive transport capacity of smectite-rich clays with high density is much lower than that of clays with low density in contrast to the cation diffusive capacity. This is explained by using quantitative microstructural data.

Removal of albumin microinjected in rat lung perimicrovascular space

1994 ◽  
Vol 77 (3) ◽  
pp. 1294-1302 ◽  
Author(s):  
X. Ying ◽  
R. Qiao ◽  
S. Ishikawa ◽  
J. Bhattacharya
Keyword(s):  
Hydraulic Conductivity ◽  
Injection Site ◽  
Time Constant ◽  
Airway Pressure ◽  
Fluorescence Decay ◽  
Diffusive Transport ◽  
Liquid Flux ◽  
Tissue Edema ◽  
Lung Expansion ◽  
Blood Flow Increase

We used a microinjection approach to assess hydraulic properties of lung perimicrovascular adventitia (interstitial cuff surrounding microvessels). Isolated blood-perfused rat lungs held at constant airway pressure were microscopically viewed to identify subpleural venules (20 microns diam). Venular adventitia were microinjected with 20 nl of fluorescent albumin (4 g/dl), and then adventitial fluorescence was quantified at the injection site by either photometery or imaging. Nonlinear decay of adventitial fluorescence indicated liquid flux from the injection site into normal interstitium. In some experiments, we determined that the adventitial fluorescence flowed longitudinally along the venule length and filled single lymphatics. The fluorescence decay at the injection site was best described by equations of convective but not diffusive transport. The decay time constant (time to 37% initial), which relates inversely to hydraulic conductivity, increased 10-fold above baseline on lung expansion with airway pressure from 5 to 15 cmH2O (P < 0.05). However, presence or absence of blood flow, increase in filtration pressure, and tissue edema were all without effect on the time constant. Our estimate of the lower limit of baseline adventitial hydraulic conductivity was 5 x 10(-6) ml.cm-2.s-1.cmH2O-1. We conclude that hydraulic conductivity of perimicrovascular adventitia is not augmented by edema but that it is decreased by lung expansion.

Vascular transport capacity of hindlimb muscles of exercise-trained rats

1987 ◽  
Vol 62 (2) ◽  
pp. 438-443 ◽  
Author(s):  
M. H. Laughlin ◽  
J. Ripperger
Keyword(s):  
Ethylenediaminetetraacetic Acid ◽  
Exchange Capacity ◽  
Transport Capacity ◽  
Diffusion Capacity ◽  
Capillary Filtration ◽  
Vascular Transport ◽  
Flow Capacity ◽  
Vascular Flow ◽  
Regional Flow ◽  
Capillary Exchange

The purpose of this study was to determine whether chronic exercise training is associated with increased vascular flow capacity and capillary exchange capacity in skeletal muscles. One group of male Sprague-Dawley rats was cage confined for a period of 13'17 wk (sedentary control, C) and a second was trained for 1 h/day at a speed of 30 m/min up a 5 degrees incline for 13–17 wk (exercise trained, ET). Studies were conducted with maximally dilated (papaverine) isolated hindquarters of 13 C rats and 10 ET rats perfused with Tyrode's solution containing 5% albumin. Vascular flow capacity was estimated by measuring total and regional flows at three to five different perfusion pressures. Capillary exchange capacity was estimated by measuring maximal capillary filtration coefficients and capillary diffusion capacity for 51Cr-ethylenediaminetetraacetic acid (51Cr-EDTA). The efficacy of the training was shown by significant increases in succinate dehydrogenase activities of the vastus intermedius muscle. Total hindquarter flow capacity was 50% higher in the ET rats. Regional flow data indicated that the higher total flow was due to increased muscle flow (85%), with the high-oxidative muscle tissue having the greatest increases (e.g., 200% increase in red gastrocnemius muscle). The maximal capillary diffusion capacity values for the ET rats were 70% greater than control values. However, the capillary filtration capacity values of the C and ET rats were not different. We conclude that the vascular transport capacity of the high-oxidative areas of extensor muscles is increased by endurance training.

A new methodology for preliminary design of centrifugal impellers with prewhirl

2019 ◽  
Vol 234 (3) ◽  
pp. 251-262 ◽  
Author(s):  
Xiaojian Li ◽  
Yijia Zhao ◽  
Zhengxian Liu ◽  
Hua Chen
Keyword(s):  
Centrifugal Compressor ◽  
Maximum Flow ◽  
High Flow ◽  
Centrifugal Impeller ◽  
Preliminary Design ◽  
Design Specification ◽  
Vaned Diffuser ◽  
Flow Capacity ◽  
Compressor Design ◽  
Aerodynamic Parameters

The overall trend of centrifugal compressor design is to strive for high aerodynamic performance and high flow capacity products. A new methodology is derived to implement a preliminary design for high flow capacity centrifugal impeller with and without prewhirl. First, several new non-dimensional equations connecting impeller geometric and aerodynamic parameters are derived for the maximum flow capacity. The effects of prewhirl on mass flow function, inlet diameter ratio and work coefficient are discussed, respectively. Then, based on these equations, a series of design diagrams are drawn to extract the universal rules in centrifugal impeller design with prewhirl. Some physical limits of design maps are also discussed. Finally, the throat area of impeller is discussed under prewhirl, and the matching principle between prewhirl impeller and vaned diffuser is derived and validated. The proposed method can be used to design a new centrifugal compressor, or to evaluate the design feasibility and the challenge of a given design specification.

High-intensity exercise training increases vascular transport capacity of rat hindquarters

1988 ◽  
Vol 254 (2) ◽  
pp. H274-H278 ◽  
Author(s):  
W. L. Sexton ◽  
R. J. Korthuis ◽  
M. H. Laughlin
Keyword(s):  
Exercise Training ◽  
High Intensity ◽  
Exchange Capacity ◽  
High Intensity Exercise ◽  
Transport Capacity ◽  
Vascular Transport ◽  
Flow Capacity ◽  
Vascular Flow ◽  
Capillary Filtration Coefficient ◽  
Capillary Exchange

The purpose of this study was to determine whether high-intensity exercise training increases the vascular flow capacity and capillary exchange capacity in isolated rat hindquarters. One group of 20 male Sprague-Dawley rats underwent six bouts of alternating running (2.5 min) and recovery (4.5 min), 5 days/wk at 60 m/min on a 15% grade for 6-10 wk (high-intensity exercise training), while a second group of 20 rats was cage confined (sedentary controls). Experiments were conducted in isolated, maximally dilated (papaverine) hindquarters perfused with an artificial plasma consisting of a Tyrode's solution containing 5 g/100 ml albumin. Vascular flow capacity was evaluated by measuring perfusate flow rate at four different perfusion pressures. Capillary exchange capacity was evaluated by measuring the capillary filtration coefficient. The efficacy of training was demonstrated by significant increases in succinate dehydrogenase activity in the white vastus lateralis and vastus intermedius muscles. Total hindquarter flow capacity was elevated 50-100% in the trained rats. This increased flow capacity was associated with an increase in the capillary filtration coefficient in the maximally vasodilated hindquarters, thus suggesting that the capillary exchange capacity was increased with high-speed exercise training. These results suggest that the vascular transport capacity in rat hindquarter muscles is significantly increased by high-intensity exercise training.

Experimental Techniques for Studying Poroelasticity in Brain Phantom Gels Under High Flow Microinfusion

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
O. Ivanchenko ◽  
N. Sindhwani ◽  
A. Linninger
Keyword(s):  
Fluid Flow ◽  
Hydraulic Conductivity ◽  
Computational Model ◽  
Alternative Pathway ◽  
Volumetric Strain ◽  
High Flow ◽  
Optical Methods ◽  
Solid Matrix ◽  
Convection Enhanced Delivery ◽  
Catheter Tip

Convection enhanced delivery is an attractive option for the treatment of several neurodegenerative diseases such as Parkinson, Alzheimer, and brain tumors. However, the occurrence of a backflow is a major problem impeding the widespread use of this technique. In this paper, we analyze experimentally the force impact of high flow microinfusion on the deformable gel matrix. To investigate these fluid structure interactions, two optical methods are reported. First, gel stresses during microinfusion were visualized through a linear polariscope. Second, the displacement field was tracked using 400 nm nanobeads as space markers. The corresponding strain and porosity fields were calculated from the experimental observations. Finally, experimental data were used to validate a computational model for fluid flow and deformation in soft porous media. Our studies demonstrate experimentally, the distribution and magnitude of stress and displacement fields near the catheter tip. The effect of fluid traction on porosity and hydraulic conductivity is analyzed. The increase in fluid content in the catheter vicinity enhances the gel hydraulic conductivity. Our computational model takes into account the changes in porosity and hydraulic conductivity. The simulations agree with experimental findings. The experiments quantified solid matrix deformation, due to fluid infusion. Maximum deformations occur in areas of relatively large fluid velocities leading to volumetric strain of the matrix, causing changes in hydraulic conductivity and porosity close to the catheter tip. The gradual expansion of this region with increased porosity leads to decreased hydraulic resistance that may also create an alternative pathway for fluid flow.

Mercury intrusion and permeability of Louiseville clay

1990 ◽  
Vol 27 (6) ◽  
pp. 761-773 ◽  
Author(s):  
Clément Lapierre ◽  
Serge Leroueil ◽  
Jacques Locat
Keyword(s):  
Hydraulic Conductivity ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Key Words ◽  
Mercury Intrusion Porosimetry ◽  
Soil Conditions ◽  
Mercury Intrusion ◽  
Remoulded Soil ◽  
Natural Clays ◽  
Unique Relationship

Several theories have been proposed to correlate the permeability (hydraulic conductivity) with the pore-size distribution of soils, and it seemed interesting to determine if these theories could be applied to natural clays. For this purpose permeability and mercury-intrusion porosimetry tests were performed on a Champlain Sea clay for both intact and remoulded conditions after compression of the specimens to strains varying from 0 to 42%. The results show that for either intact or remoulded soil conditions, there is a relationship between the pore-size parameters and the permeability of the clay. However, there is no unique relationship for both intact and remoulded clays and for the silt and clay considered in previous studies. Consequently, mercury-intrusion porosimetry alone cannot be used to evaluate the permeability of soils in general. Key words: permeability, clays, mercury-intrusion porosimetry, fabric.

Specific Hydraulic Conductivity of Corneal Stroma as Seen by Quick-Freeze/Deep-Etch

2000 ◽  
Vol 123 (2) ◽  
pp. 154-161 ◽  
Author(s):  
Darryl Overby ◽  
Jeffrey Ruberti ◽  
Haiyan Gong ◽  
Thomas F. Freddo ◽  
Mark Johnson
Keyword(s):  
Extracellular Matrix ◽  
Hydraulic Conductivity ◽  
Flow Resistance ◽  
Corneal Stroma ◽  
High Flow ◽  
Depth Of Field ◽  
Resistance Characteristic ◽  
Connective Tissues ◽  
Electron Microscopic ◽  
Microscopic Techniques

Previous studies of the hydraulic conductivity of connective tissues have failed to show a correspondence between ultrastructure and specific hydraulic conductivity. We used the technique of quick-freeze/deep-etch to examine the ultrastructure of the corneal stroma and then utilized morphometric studies to compute the specific hydraulic conductivity of the corneal stroma. Our studies demonstrated ultrastructural elements of the extracellular matrix of the corneal stroma that are not seen using conventional electron microscopic techniques. Furthermore, we found that these structures may be responsible for generating the high flow resistance characteristic of connective tissues. From analysis of micrographs corrected for depth-of-field effects, we used Carmen-Kozeny theory to bound a morphometrically determined specific hydraulic conductivity of the corneal stroma between 0.46×10−14 and 10.3×10−14 cm2. These bounds encompass experimentally measured values in the literature of 0.5×10−14 to 2×10−14 cm2. The largest source of uncertainty was due to the depth-of-field estimates that ranged from 15 to 51 nm; a better estimate would substantially reduce the uncertainty of these morphometrically determined values.

Pilot operated miniature valve with fast response and high flow capacity

2014 ◽  
Vol 15 (1) ◽  
pp. 11-18 ◽  
Author(s):  
Tapio Lantela ◽  
Jyrki Kajaste ◽  
Jari Kostamo ◽  
Matti Pietola
Keyword(s):  
Fast Response ◽  
High Flow ◽  
Flow Capacity

Vascular adaptations in rat hindlimb skeletal muscle after voluntary running-wheel exercise

1995 ◽  
Vol 79 (1) ◽  
pp. 287-296 ◽  
Author(s):  
W. L. Sexton
Keyword(s):  
Skeletal Muscle ◽  
Transport Capacity ◽  
Running Wheel ◽  
Capillary Filtration ◽  
Vascular Transport ◽  
Flow Capacity ◽  
Voluntary Running ◽  
Capillary Filtration Coefficient ◽  
Running Wheel Exercise ◽  
Long Head

To test the hypothesis that voluntary running-wheel exercise would elicit vascular adaptations in rat skeletal muscle, male Sprague-Dawley rats (202 +/- 5 g) were cage confined (C, n = 11) or housed in cages with free access to running wheels (R, n = 13) for 12 wk. Vascular transport capacity was determined in maximally vasodilated (papaverine) hindquarters of C and R rats with measurements of total and regional (radiolabeled microspheres) flow capacity and capillary filtration coefficient. R rats voluntarily ran 29 +/- 4 km/wk over the 12-wk period; however, performance of individual rats varied greatly (range 4–74 km/wk). Citrate synthase activity was increased in the medial head (81%, P < 0.001) and the red long head (88%, P < 0.001) of the triceps brachii muscle in R rats but not in the white long head (25%, P = 0.06). Capillary filtration coefficient was 27% greater in R compared with C rats (0.040 +/- 0.003 vs. 0.031 +/- 0.002 ml.min-1.100 g-1.mmHg-1, respectively, P < 0.001) suggesting that there was an increase in microvascular surface area available for fluid exchange. Total hindquarters flow was increased in R rats (P < 0.05) at all perfusion pressures examined, indicative of an increased flow capacity. Regional flows revealed that skin flow was unchanged in R rats and that the increase in total flow was due to increased skeletal muscle flow capacity. These results indicate that voluntary running-wheel exercise elicits adaptive increases in skeletal muscle vascular transport capacity and oxidative capacity comparable to those seen in treadmill-trained rats and support the use of voluntary running-wheel exercise as a less stressful training modality in exercise studies using rats.

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