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Lecture Quiz 2.0 was the first prototype where both teacher and student clients had web-interfaces. An experiment testing the 2.0 prototype showed that the usability had been improved both for the teacher and the student clients, and that the concept increased students' motivation, engagement, concentration, and perceived learning. [29]
Fluid mosaic model of a cell membrane. The fluid mosaic model explains various characteristics regarding the structure of functional cell membranes.According to this biological model, there is a lipid bilayer (two molecules thick layer consisting primarily of amphipathic phospholipids) in which protein molecules are embedded.
Thermodynamically the flow of substances from one compartment to another can occur in the direction of a concentration or electrochemical gradient or against it. If the exchange of substances occurs in the direction of the gradient, that is, in the direction of decreasing potential, there is no requirement for an input of energy from outside the system; if, however, the transport is against ...
Membrane scaling, like other types of membrane fouling, increases energy costs due to higher operating pressure, and reduces permeate water production. [2] Furthermore, scaling may damage and shorten the lifetime of membranes due to frequent membrane cleanings [3] and therefore it is a major operational challenge in RO applications.
A typical flow battery consists of two tanks of liquids which are pumped past a membrane held between two electrodes. [1]A flow battery, or redox flow battery (after reduction–oxidation), is a type of electrochemical cell where chemical energy is provided by two chemical components dissolved in liquids that are pumped through the system on separate sides of a membrane.
Dense membranes are utilized for gas separations (removal of CO 2 from natural gas, separating N 2 from air, organic vapor removal from air or a nitrogen stream) and sometimes in membrane distillation. The later process helps in the separation of azeotropic compositions reducing the costs of distillation processes.
While polymeric membranes are economical and technologically useful, they are bounded by their performance, known as the Robeson limit (permeability must be sacrificed for selectivity and vice versa). [2] This limit affects polymeric membrane use for CO 2 separation from flue gas streams, since mass transport becomes limiting and CO 2 ...
Cross-sectional view of the structures that can be formed by phospholipids in an aqueous solution. A biological membrane, biomembrane or cell membrane is a selectively permeable membrane that separates the interior of a cell from the external environment or creates intracellular compartments by serving as a boundary between one part of the cell and another.