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Countercurrent exchange

About: Countercurrent exchange is a research topic. Over the lifetime, 2255 publications have been published within this topic receiving 28687 citations. The topic is also known as: Countercurrent exchange.


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Journal ArticleDOI
TL;DR: In this article, a detailed analysis of the rete mirabile of the European eel revealed the expression of a large number of transport proteins in rete capillaries, so that the back diffusion of ions and metabolites, in particular lactate, may significantly enhance the countercurrent concentrating ability of rete.
Abstract: BACKGROUND In physoclist fishes filling of the swimbladder requires acid secretion of gas gland cells to switch on the Root effect and subsequent countercurrent concentration of the initial gas partial pressure increase by back-diffusion of gas molecules in the rete mirabile. It is generally assumed that the rete mirabile functions as a passive exchanger, but a detailed analysis of lactate and water movements in the rete mirabile of the eel revealed that lactate is diffusing back in the rete. In the present study we therefore test the hypothesis that expression of transport proteins in rete capillaries allows for back-diffusion of ions and metabolites, which would support the countercurrent concentrating capacity of the rete mirabile. It is also assumed that in silver eels, the migratory stage of the eel, the expression of transport proteins would be enhanced. RESULTS Analysis of the transcriptome and of the proteome of rete mirabile tissue of the European eel revealed the expression of a large number of membrane ion and metabolite transport proteins, including monocarboxylate and glucose transport proteins. In addition, ion channel proteins, Ca2+-ATPase, Na+/K+-ATPase and also F1F0-ATP synthase were detected. In contrast to our expectation in silver eels the expression of these transport proteins was not elevated as compared to yellow eels. A remarkable number of enzymes degrading reactive oxygen species (ROS) was detected in rete capillaries. CONCLUSIONS Our results reveal the expression of a large number of transport proteins in rete capillaries, so that the back diffusion of ions and metabolites, in particular lactate, may significantly enhance the countercurrent concentrating ability of the rete. Metabolic pathways allowing for aerobic generation of ATP supporting secondary active transport mechanisms are established. Rete tissue appears to be equipped with a high ROS defense capacity, preventing damage of the tissue due to the high oxygen partial pressures generated in the countercurrent system.

2 citations

Patent
13 Jul 2016
TL;DR: In this article, a tail heat utilized hot-air type penetration countercurrent fluidized drying machine is used to improve the drying efficiency of a large-scale draught fan. But, the problem that the fan is continuously automatically locked and is not easy to disassemble under the action of load in threaded assembling can be effectively solved.
Abstract: The invention discloses a tail heat utilized hot-air type penetration countercurrent fluidized drying machine A draught fan is connected to the upper part of a drying tower; the draught fan is tangentially connected with a cyclone dust removal tail heat efficient recoverer which is formed by a tube type heat exchanger and a cyclone dust collector which are overlapped, and is evacuated; the shell pass air inlet end of the tube type heat exchanger is communicated with the atmosphere; the air outlet of the tube type heat exchanger is connected to the lower part of the drying tower through an air blower and a steam fin heater; blades of the draught fan impeller are arranged in a radiation manner that impeller shafts are in radial and central symmetry; dust can be collected by virtue of centrifugal force in time, and thus security accidents can be avoided By adopting the tail heat utilized hot-air type penetration countercurrent fluidized drying machine, the drying efficiency is improved, the purposes of energy conservation and emission reduction are achieved, more importantly, the assembling and disassembling technique of the draught fan is greatly improved, pressure caused by components such as a screw nut to the shoulder end surface of a screw shaft can be easily eliminated when the draught fan is assembled and disassembled, the problem that the draught fan is continuously automatically locked and is not easy to disassemble under the action of load in threaded assembling can be effectively solved, and the tail heat utilized hot-air type penetration countercurrent fluidized drying machine is particularly applicable to convenient and rapid disassembling after a large-size draught fan is in threaded locking and is particularly remarkable in effect

2 citations

Patent
10 Oct 1985
TL;DR: In this article, a countercurrent continuous catalytic reactor and process for treating a liquid phase, such as oil, with a gaseous reactant is described, where a level detector 30 is disposed in a froth zone above the catalyst bed 12 for detecting level of a mixed gas-liquid froth.
Abstract: A countercurrent continuous catalytic reactor and process for treating a liquid phase, such as oil, with a gaseous reactant. An enclosed reactor shell 10 contains a fixed porous bed 12 of solid catalyst, an upper liquid inlet 14 for introducing a stream of liquid substantially above the catalyst bed 12 for downward gravity flow through the bed, and a lower liquid outlet 16 for withdrawing treated liquid from the reactor shell 10. A gaseous reactant is dispersed through the liquid phase in intimate contact with the solid catalyst, and withdrawn above the catalyst bed 12. A level detector 30 is disposed in a froth zone above the catalyst bed 12 for detecting level of a mixed gas-liquid froth. Fluid handling control 32 responsive to a level signal controls fluid stream flow for regulating froth level above the catalyst bed 12.

2 citations

Journal ArticleDOI
TL;DR: In this article, a countercurrent crystallization purification column was developed which produces a high purity product by continuous countercurrent treatment of the crystal mass with some of the melted crystal product.
Abstract: Fractional crystallization has not been as widely used commercially as its potential value as a powerful separation tool justifies, because equipment has remained undeveloped and inefficient and distillation has usually been used. In exploring a new approach to the development of more efficient equipment, a crystallization purification column was developed which produces a high purity product by continuous countercurrent treatment of the crystal mass with some of the melted crystal product.We investigated this countercurrent crystallization purification apparatus, and analysed the various phenomena in the purification processes: i. e. the relation between the falling rate of porous piston and the heat supplied at the bottom of the column, the effect of pressure on the purifying capacity of the equipment, temperature distribution and concentrations of products. The transfer processes of heat and mass in this column were analysed by a simple model for the crystallization process, and experimental results were compared with the theory. From these results the transfer coefficient and H.T.U. of this column were estimated.

2 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202358
2022115
202127
202041
201947
201849