Pathways of ion movement in the canine tracheal epithelium

1980 ◽  
Vol 239 (3) ◽  
pp. F215-F221 ◽  
Author(s):  
M. J. Welsh ◽  
J. H. Widdicombe
Keyword(s):  
Open Circuit ◽  
Paracellular Pathway ◽  
Tracheal Epithelium ◽  
Ion Movement ◽  
Voltage Dependent ◽  
Transepithelial Voltage ◽  
Unidirectional Fluxes ◽  
Open Circuit Condition ◽  
Hydrophilic Molecule ◽  
Cl Permeability

The pathways of ion movement across canine tracheal epithelium, a Cl-secreting tissue, were examined by three techniques. First, the measurement of simultaneous, unidirectional fluxes of Na or Cl and mannitol, a large hydrophilic molecule that serves as a marker of the paracellular pathway, indicated that a significant fraction of both the Na flux from submucosa to mucosa (J Na sm) and the flux of Cl from mucosa to submucosa (J Cl ms) traverse the cellular pathway. The ratio of the Na-to-Cl diffusion coefficients through the paracellular pathway was 0.23, in contrast to the free solution ratio of 0.63. Second, in voltage-clamp experiments we examined the effect of transepithelial voltage differences on the unidirectional fluxes of Na and Cl. The results agree with the previous findings, suggesting that there are voltage-independent, or transcellular, backfluxes of Na and Cl, and that the relative permeability of Na to Cl through the voltage-dependent (presumably paracellular) pathway was 0.28. Third, measurement of transepithelial diffusion potentials gave a Na-to-Cl permeability ratio of 0.31 +/- 0.02 (mean +/- SE). These results suggest that there are significant transcellular backfluxes of Na and Cl and that the paracellular pathway in the canine trachea is anion selective. An anion-selective pathway would tend to shunt the secreted Cl back through the paracellular pathway, thus minimizing the net ion and fluid movement across the tissue in the open-circuit condition.

Protamine alters apical membrane K+ and Cl- permeability in gallbladder epithelium

1987 ◽  
Vol 253 (5) ◽  
pp. C662-C671 ◽  
Author(s):  
S. M. Poler ◽  
L. Reuss
Keyword(s):  
Time Course ◽  
Apical Membrane ◽  
Membrane Resistance ◽  
Gallbladder Epithelium ◽  
Negative Change ◽  
High K ◽  
Solution Bathing ◽  
Transepithelial Voltage ◽  
Mucosal Side ◽  
Cl Permeability

Protamine addition to the solution bathing the mucosal side of Necturus gallbladder epithelium (25-100 mg/l) caused depolarization of both cell membranes, a mucosa-negative change in transepithelial voltage, an increase in the apical membrane resistance (Ra) followed by a decrease, and a monotonic increase in transepithelial resistance (Rt). In protamine (25 mg/l), the change in apical membrane voltage elicited by elevating mucosal solution [K+] from 2.5 to 92.5 mM was reduced from 66 +/-2 to 38 +/- 5 mV (P less than 0.001). The K+-induced fall in Ra was also reduced in protamine. These effects could also be elicited by elevating mucosal solution [K+] simultaneously with the addition of protamine and by transient addition of protamine during exposure to the high K+ medium. The effect of protamine on the electrodiffusive Cl- permeability of the apical membrane (PCl) was studied both in control and forskolin-treated tissues. In the absence of forskolin, the hyperpolarization of Vmc produced by lowering mucosal [Cl-] to 10 mM was reversed to a small depolarization; in forskolin, the initial depolarization produced by lowering [Cl-] was significantly increased. Finally, exposure to protamine in the absence of forskolin produced an initial fall in intracellular Cl- activity. Our results indicate that protamine decreases apical membrane K+ permeability and increases apical membrane PCl. The time course of the effects of protamine suggests the possibility of an initial effect on surface potential, followed by secondary actions mediated by intracellular events.

Electrical and Optical Characterisation of Silicon Nanocrystals Embedded in SiC

2013 ◽  
Vol 205-206 ◽  
pp. 480-485 ◽  
Author(s):  
Manuel Schnabel ◽  
Philipp Löper ◽  
Mariaconcetta Canino ◽  
Sergey A. Dyakov ◽  
Marco Allegrezza ◽  
...  
Keyword(s):  
Solar Cell ◽  
Silicon Nanocrystals ◽  
Carrier Mobility ◽  
Open Circuit Voltage ◽  
Open Circuit ◽  
Promising Candidate ◽  
Current Collection ◽  
Interference Correction ◽  
Voltage Dependent ◽  
Minority Carrier Mobility

Silicon nanocrystals (Si NCs) are a promising candidate for the top cell of an all-Si tandem solar cell with a band gap from 1.3-1.7 eV, tuneable by adjusting NC size. They are readily produced within a Si-based dielectric matrix by precipitation from the Si excess in multilayers of alternating stoichiometric and silicon-rich layers. Here we examined the luminescence and transport of Si NCs embedded in SiC. We observed luminescence that redshifts from 2.0 to 1.5 eV with increasing nominal NC size. Upon further investigation, we found that this redshift is to a large extent due to Fabry-Pérot interference. Correction for this effect allows an analysis of the spectrum emitted from within the sample. We also produced p-i-n solar cells and found that the observed I-V curves under illumination could be well-fitted by typical thin-film solar cell models including finite series and parallel resistances, and a voltage-dependent current collection function. A minority carrier mobility-lifetime product on the order of 10-10 cm2/V was deduced, and a maximum open-circuit voltage of 370 mV achieved.

scholarly journals Experimental Research on Power Transformer Vibration Distribution under Different Winding Defect Conditions

Electronics ◽  
2019 ◽  
Vol 8 (8) ◽  
pp. 842
Author(s):  
Yiwei Hu ◽  
Jing Zheng ◽  
Hai Huang
Keyword(s):  
Spatial Distribution ◽  
Vibration Analysis ◽  
Power Transformer ◽  
Open Circuit ◽  
Distribution Characteristics ◽  
Spatial Distribution Characteristics ◽  
Three Phase ◽  
Transformer Winding ◽  
Faults Diagnosis ◽  
Open Circuit Condition

Vibration analysis is one of the important tools for the transformer winding faults diagnosis. Previous researchers have proved that the vibration spatial distribution of the winding is significantly influenced by the winding defects for the open circuit condition. In order to study the effects of the loading current on the winding vibrations under different mechanical conditions, experiments were designed and operated on a three-phase transformer winding to analyze the winding vibration distribution under different winding defect cases. Further, to study to what extent the mechanical defects and the loading current influence characteristics of the vibration distribution on the tank, the tank vibration distribution under various winding defects and different loading currents were also measured and discussed. In addition, the possibility of detection of transformer winding faults based on tank vibration spatial distribution characteristics was also discussed.

Furosemide-sensitive Cl transport in embryonic chicken retinal pigment epithelium

1983 ◽  
Vol 244 (6) ◽  
pp. F679-F685 ◽  
Author(s):  
D. A. Frambach ◽  
D. S. Misfeldt
Keyword(s):  
Retinal Pigment Epithelium ◽  
Pigment Epithelium ◽  
Ussing Chamber ◽  
Retinal Pigment ◽  
Open Circuit ◽  
Transepithelial Transport ◽  
Free Medium ◽  
Cl Transport ◽  
Embryonic Chicken ◽  
Transepithelial Voltage

Retinal pigment epithelium- (RPE) choroid-sclera preparations from embryonic chickens were mounted in an Ussing chamber. A spontaneous transepithelial voltage (Ve) of 5.1 mV (retinal side positive) and a resistance of 114 omega . cm2 can be attributed to the RPE. Furosemide and ouabain inhibited the Ve without affecting the resistance when applied to the retinal surface of the preparation but had no effect when applied to the scleral surface. Acetazolamide and amiloride were without effect when applied to either surface. The Ve fell by 100% in Na-free medium, by 70% in Cl-free medium, and was unchanged in HCO3-free medium. When Na and Cl were returned to the medium, the Ve recovered. Dilution potentials and unidirectional flux studies indicated that the RPE is more permeable to Na than to Cl. Isotope flux studies performed under open-circuit conditions showed a net retina-to-choroid flux for both Na and Cl with the net Cl flux abolished by furosemide. Analysis of the Na+ and Cl- electrochemical gradients and the Na permeability across the RPE suggests that the net retina-to-choroid Na+ flux is largely passive, whereas the net retina-to-choroid Cl- flux results from active transport. These results indicate that embryonic chicken RPE possesses furosemide-sensitive Cl transport function. A model of embryonic chicken RPE transepithelial transport is presented.

Manufacture and Experimental Investigation of a Multi-Layer Generator Based on Dielectric Elastomer

2014 ◽  
Vol 960-961 ◽  
pp. 1336-1341
Author(s):  
Xue Jing Liu ◽  
Gong Zhang ◽  
Yong Quan Wang ◽  
Shu Hai Jia
Keyword(s):  
Energy Harvesting ◽  
Light Emitting Diode ◽  
Electrical Energy ◽  
Dielectric Elastomer ◽  
Maximum Energy ◽  
Open Circuit ◽  
Light Emitting ◽  
Energy Harvesting Efficiency ◽  
Open Circuit Condition ◽  
Constant Charge

As a member of Electroactive Polymers (EAPs), dielectric elastomer (DE) has shown considerable potential for energy harvesting applications. After the basic principle of DE energy harvesting is studied, a multi-layer DE generator using VHB 4910 (3M, USA) is specially designed and fabricated. Then, an improved energy harvesting circuit is designed to make use of harvested electrical energy. Finally, energy harvesting experiments are implemented under the constant charge (open-circuit) condition and the results prove that the multi-layer DE generator fabricated can produce enough energy to constantly drive a light emitting diode. The harvested electrical energy has good consistent with generated electrical energy and the maximum energy harvesting efficiency ηh can reach 89%.

Magnetohydrodynamic Effects in Composite Bearings

1967 ◽  
Vol 89 (3) ◽  
pp. 323-328 ◽  
Author(s):  
J. Prakash
Keyword(s):  
Hartmann Number ◽  
Load Capacity ◽  
Short Circuit ◽  
Electrical Energy ◽  
Open Circuit ◽  
Slider Bearing ◽  
Frictional Drag ◽  
Electrically Conducting ◽  
Open Circuit Condition ◽  
Composite Bearing

A theoretical analysis is made of a composite slider bearing using an electrically conducting lubricant such as a liquid metal in the presence of a magnetic field applied perpendicular to the bearing surfaces. Two solutions are presented for large and small values of Hartmann number. It is found that for large Hartmann number significant increase in load capacity can be obtained even under open circuit condition. Short circuit condition results in zero load capacity, under the approximation considered. At small Hartmann number only a slight increase occurs under open circuit condition and external power must be supplied to get a significant increase. It is seen that a magnetohydrodynamic composite bearing does not always give an increase in load capacity as compared to an equivalent inclined slider bearing, as is the case with classical composite bearing. There is a critical Hartmann number depending on the parameters of the problem, above which MHD effects reduce the load capacity as compared to the case of an equivalent inclined slider bearing. It is also observed that the frictional drag on the bearing can be made zero by supplying electrical energy through the electrodes to the fluid.

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