An Analysis of Unicellular Mass Transfer Using a Microfabricated Experimental Technique

2000 ◽  
Author(s):  
Kelvan Howard ◽  
Boris Rubinsky
Keyword(s):  
Mass Transfer ◽  
Standard Deviation ◽  
Reflection Coefficient ◽  
Membrane Permeability ◽  
Experimental Technique ◽  
Water Permeability ◽  
Permeability Coefficient ◽  
Volume Changes ◽  
Flow Paths

Abstract This study introduces a microfabricated chamber which allows individual cells to be maintained between two different flow paths while kinetic volume changes and membrane permeability are measured. For HBL-100 cells, the data yielded a water permeability (Lp) of 1.1 ±0.5 μm/(min-atm) (mean ± 1 standard deviation) (N = 5) during the uncoupled transport of water at 22°C. In the presence of 6M glycerol, the water permeability (Lp), permeability coefficient (Ps), and the reflection coefficient (σs) were determined to be 2.0± 0.63 μm/(min-atm), 2.7×10E-5 ±6.1×10E-6 cm-sec−1, and 0.76±.05 (N = 6). No previous values of these coefficients could be found for HBL-100 cells.

scholarly journals Implementation of Spiegler–Kedem and Steric Hindrance Pore Models for Analyzing Nanofiltration Membrane Performance for Smart Water Production

Membranes ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 78 ◽  
Author(s):  
Remya Nair ◽  
Evgenia Protasova ◽  
Skule Strand ◽  
Torleiv Bilstad
Keyword(s):  
Mass Transfer ◽  
Reflection Coefficient ◽  
Oil Recovery ◽  
Water Permeability ◽  
Structural Parameters ◽  
Pure Water ◽  
Model Parameters ◽  
Water Production ◽  
Solute Permeability ◽  
Smart Water

A predictive model correlating the parameters in the mass transfer-based model Spiegler–Kedem to the pure water permeability is presented in this research, which helps to select porous polyamide membranes for enhanced oil recovery (EOR) applications. Using the experimentally obtained values of flux and rejection, the reflection coefficient σ and solute permeability Ps have been estimated as the mass transfer-based model parameters for individual ions in seawater. The reflection coefficient and solute permeability determined were correlated with the pure water permeability of a membrane, which is related to the structural parameters of a membrane. The novelty of this research is the development of a model that consolidates the various complex mechanisms in the mass transfer of ions through the membrane to an empirical correlation for a given feed concentration and membrane type. These correlations were later used to predict ion rejections of any polyamide membrane with a known pure water permeability and flux with seawater as a feed that aids in the selection of suitable nanofiltration (NF) for smart water production.

scholarly journals Biologically effective dose correlates with linear tumor volume changes after upfront single-fraction stereotactic radiosurgery for vestibular schwannomas

2021 ◽  
Author(s):  
Constantin Tuleasca ◽  
Mohamed Faouzi ◽  
Philippe Maeder ◽  
Raphael Maire ◽  
Jonathan Knisely ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Effective Dose ◽  
Stereotactic Radiosurgery ◽  
Tumor Volume ◽  
Vestibular Schwannomas ◽  
Benign Tumors ◽  
Biologically Effective Dose ◽  
Volume Changes ◽  
Single Fraction

AbstractVestibular schwannomas (VSs) are benign, slow-growing tumors. Management options include observation, surgery, and radiation. In this retrospective trial, we aimed at evaluating whether biologically effective dose (BED) plays a role in tumor volume changes after single-fraction first intention stereotactic radiosurgery (SRS) for VS. We compiled a single-institution experience (n = 159, Lausanne University Hospital, Switzerland). The indication for SRS was decided after multidisciplinary discussion. Only cases with minimum 3 years follow-up were included. The Koos grading, a reliable method for tumor classification was used. Radiosurgery was performed using Gamma Knife (GK) and a uniform marginal prescription dose of 12 Gy. Mean BED was 66.3 Gy (standard deviation 3.8, range 54.1–73.9). The mean follow-up period was 5.1 years (standard deviation 1.7, range 3–9.2). The primary outcome was changes in 3D volumes after SRS as function of BED and of integral dose received by the VS. Random-effect linear regression model showed that tumor volume significantly and linearly decreased over time with higher BED (p < 0.0001). Changes in tumor volume were also significantly associated with age, sex, number of isocenters, gradient index, and Koos grade. However, the effect of BED on tumor volume change was moderated by time after SRS and Koos grade. Lower integral doses received by the VSs were inversely correlated with BED in relationship with tumor volume changes (p < 0.0001). Six (3.4%) patients needed further intervention. For patients having uniformly received the same marginal dose prescription, higher BED linearly and significantly correlated with tumor volume changes after SRS for VSs. BED could represent a potential new treatment paradigm for patients with benign tumors, such as VSs, for attaining a desired radiobiological effect. This could further increase the efficacy and decrease the toxicity of SRS not only in benign tumors but also in other SRS indications.

scholarly journals Impact of Biochar on Soil Water Permeability Coefficient During 2 Year Field Experiment

2020 ◽  
Vol 609 ◽  
pp. 012108
Author(s):  
Maciej Gliniak ◽  
Jakub Sikora ◽  
Urszula Sadowska ◽  
Agnieszka Klimek-Kopyra ◽  
Agnieszka Latawiec ◽  
...  
Keyword(s):  
Field Experiment ◽  
Soil Water ◽  
Water Permeability ◽  
Permeability Coefficient ◽  
Water Permeability Coefficient

Influence of Injection Type and Feed Arrangement on Flow and Heat Transfer in an Injection Slot

2001 ◽  
Vol 124 (1) ◽  
pp. 132-141 ◽  
Author(s):  
Hyung Hee Cho ◽  
Jin Ki Ham
Keyword(s):  
Mass Transfer ◽  
Heat Mass Transfer ◽  
Cooling System ◽  
Transfer Coefficients ◽  
Counter Flow ◽  
Flow Paths ◽  
Mass Transfer Coefficients ◽  
Naphthalene Sublimation Technique ◽  
Vertical Injection ◽  
Injection Type

An experimental investigation is conducted to improve a slot film cooling system used for the cooling of a gas turbine combustor liner. The tangential slots are constructed of discrete holes with different injection types which are the parallel, vertical, and combined to the slot lip. The investigation is focused on the coolant supply systems of normal, inline, and counter-flow paths to the mainstream flow direction. A naphthalene sublimation technique has been employed to measure the local heat/mass transfer coefficients in a slot wall with various injection types and coolant feeding directions. A numerical simulation is also conducted to help understand the flow patterns inside the slot for different injection types. The velocity distributions at the exit of slot lip for the parallel and vertical injection types are fairly uniform with mild periodical patterns with respect to the injection hole positions. However, the combined injection type increases the nonuniformity of flow distribution with the period equaling twice that of hole-to-hole pitch due to splitting and merging of the ejected flows. The dimensionless temperature distributions at the slot exits differ little with blowing rates, injection types, and secondary flow conditions. In the results of heat/mass transfer measurements, the best cooling performance inside the slot is obtained with the vertical injection type among the three different injection types due to the effects of jet impingement. The lateral distributions of heat/mass transfer coefficients with the inline and counter-flow paths are more uniform than the normal-flow path. The average heat/mass transfer coefficients with the injection holes are about two to five times higher than that of a smooth two-dimensional slot path.

scholarly journals Annexin A4 Reduces Water and Proton Permeability of Model Membranes but Does Not Alter Aquaporin 2–mediated Water Transport in Isolated Endosomes

2003 ◽  
Vol 121 (5) ◽  
pp. 413-425 ◽  
Author(s):  
Warren G. Hill ◽  
Marcia A. Kaetzel ◽  
Bellamkonda K. Kishore ◽  
John R. Dedman ◽  
Mark L. Zeidel
Keyword(s):  
Membrane Permeability ◽  
Water Permeability ◽  
Membrane Trafficking ◽  
Collecting Duct ◽  
Water Flux ◽  
Physiological Role ◽  
Apical Region ◽  
Proton Permeability ◽  
Aquaporin 2 ◽  
Annexin A4

Annexin A4 (Anx4) belongs to a ubiquitous family of Ca2+-dependent membrane-binding proteins thought to be involved in membrane trafficking and membrane organization within cells. Anx4 localizes to the apical region in epithelia; however, its physiological role is unclear. We show that Anx4 exhibited binding to liposomes (phosphatidylcholine:phosphatidylserine, 1:1) in the presence of Ca2+ and binding was reversible with EDTA. Anx4 binding resulted in liposome aggregation and a reduction in membrane water permeability of 29% (P &lt; 0.001) at 25°C. These effects were not seen in the presence of Ca2+ or Anx4 alone and were reversible with EDTA. Measurements of membrane fluidity made by monitoring fluorescence anisotropy of 2-(12-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)dodecanoyl-1-hexadecanoyl-sn-glycero-3-phosphocholine (NBD-HPC) demonstrated that Anx4 binding rigidified the outer leaflet of the bilayer (P &lt; 0.001), thus providing a molecular explanation for the inhibition of water flux. To determine whether Anx4 would produce similar effects on physiological membranes we constructed liposomes which recapitulated the lipid composition of the inner leaflet of the MDCK apical membrane. These membranes exhibited reductions to water permeability upon Anx4 binding (19.5% at 25°C, 31% at 37°C; P &lt; 0.01 and P &lt; 0.001, respectively) and to proton permeability (15% at 25°C, 19.5% at 37°C; P &lt; 0.05). Since our in vitro experiments indicated an effect on membrane permeability, we examined localization of Anx4 in the kidney collecting duct, a region of the nephron responsible for concentrating urine through water reabsorbtion. Anx4 was shown to colocalize apically with aquaporin 2 (AQP2) in collecting duct epithelia. To test for the existence of a functional interaction between Anx4 and AQP2 we isolated AQP2-containing endosomes and exposed them to Anx4/Ca2+. Water flux rates were unchanged, indicating Anx4 does not directly regulate AQP2. We conclude that Anx4 can alter the physical properties of membranes by associating with them and regulate passive membrane permeability to water and protons. These properties represent important new functions for Anx4.

Water permeability of alveolar macrophages

1986 ◽  
Vol 251 (4) ◽  
pp. C524-C528 ◽  
Author(s):  
R. A. Garrick ◽  
T. G. Polefka ◽  
W. O. Cua ◽  
F. P. Chinard
Keyword(s):  
Cell Volume ◽  
Alveolar Macrophages ◽  
Permeability Coefficient ◽  
High Ratio ◽  
Volume Changes ◽  
Membrane Pores ◽  
Linear Relationships ◽  
Diffusional Permeability ◽  
Water Passage ◽  
Suspended Cells

The hydraulic conductivity coefficient (Lp) of alveolar macrophages, recovered by lavage from dog lungs, was determined by following volume changes induced by changes of nonpermeating solute concentrations of suspending fluid as a function of time at 20 degrees C. The volume changes were monitored as changes in absorbance of the suspended cells at 600 nm. Cell surface area was calculated from cell volume and diameter. Linear relationships between cell volume and solution osmolality changes were found over the range of 320-520 mosmol/kg; beyond these ranges the macrophages did not respond with swelling or shrinking. Lp and the filtration coefficient (Pf) were calculated from the total volume change over time. At 20 degrees C these were, respectively, 15.7 X 10(-10) cm X cmH2O-1 X s-1 and 217 X 10(-5) cm/s. Comparison of Pf and the diffusional permeability coefficient (Pd) for water of 70 X 10(-5) cm/s, yields a Pf-to-Pd ratio of 3.1. The hypothesis of water passage through aqueous membrane pores is compatible with these data. However, diffusion of water in the glycocalyx of the pericellular domain could be restricted. Pd would then be underestimated, and a falsely high ratio would be calculated. We have no evidence to support this possibility.

Cell osmotic water permeability of isolated rabbit proximal straight tubules

1982 ◽  
Vol 242 (4) ◽  
pp. F321-F330 ◽  
Author(s):  
E. Gonzalez ◽  
P. Carpi-Medina ◽  
G. Whittembury
Keyword(s):  
Surface Area ◽  
Water Flow ◽  
Water Permeability ◽  
Permeability Coefficient ◽  
Osmotic Water Permeability ◽  
Water Permeability Coefficient ◽  
Osmotic Water ◽  
Straight Tubules ◽  
Tubular Surface ◽  
Set Up

Proximal straight tubules were dissected and mounted in a chamber with their lumina occluded. The well-stirred bath could be 95% changed within 84 ms to set up osmotic gradients (delta Coi) across the peritubular cell aspect. Volume changes (less than or equal to 10 pl/mm) were estimated from continuous records of diameter changes (error less than 0.1 micrometers). delta Coi greater than or equal to 2-3 mosM could be discerned. delta Coi values from 10 to 44 mosM were used to evaluate Posc, the cell osmotic water permeability coefficient, and extrapolated to delta Coi = 0. Posc = 25.1 (+/- 2.3) X 10(-4) cm3.s-1.osM-1.cm2 tubular surface area-1. These values are lower than those reported for Pose, the transepithelial osmotic water permeability coefficient, and become lower if corrected for the real (infolded) peritubular cell surface area. Thus, for a given osmotic difference, transcellular water flow finds a higher resistance than paracellular water flow. Experiments were also performed with delta Coi greater than 100 mosM, but interpretation of these data is difficult because of the presence of volume regulatory phenomena and other undesirable effects.

scholarly journals Permeability of Concrete and Correlation with Microstructure Parameters Determined by 1H NMR

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Yurong Zhang ◽  
Shengxuan Xu ◽  
Zhaofeng Fang ◽  
Junzhi Zhang ◽  
Chaojun Mao
Keyword(s):  
Water Permeability ◽  
Permeability Coefficient ◽  
Pore Diameter ◽  
Gas Permeability ◽  
Steady State Flow ◽  
Test Device ◽  
Water Permeability Coefficient ◽  
Microstructure Parameters ◽  
The Relationship ◽  
Better Than

Water and gas permeability coefficients of concrete with different water-binder (w/b) ratios and admixtures were measured by a self-designed test device based on the steady-state flow method for liquid and the method of differential pressure in stability for gas, respectively. In addition, the micropore structure of concrete was determined by 1H nuclear magnetic resonance (NMR). Results indicated that there are good correlations between water and gas permeability of concrete with different w/b ratios, with correlation coefficient greater than 0.90. Better correlations between water permeability and segmental contributive porosity ranged from 10 to 100 nm and 100 to 1000 nm can be identified, but the gas permeability is more relevant to the segmental contributive porosity ranging from 100 to 1000 nm. Moreover, the correlation between water permeability and contributive porosity for each pore diameter is always better than that of gas permeability. The influence of admixtures on the relationship between permeability and pore size distribution of concrete is significant. Moreover, water permeability coefficient is one or two orders of magnitude lower than the gas permeability coefficient.

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