Critical stress, membrane

Similar to beam buckling, membrane buckling is another important mechanism for thermal expansion microvalves. To investigate the bending of a membrane when heat is added to it. Fig. lb illustrates the principle of the thermal buckling of a square membrane. Considering a uniform compression condition across the membrane (i.e., the compressive stress is constant, Sx = Sy = S), the membrane buckles transversally without any additional external load when the compressive stress gradually increases with temperature and exceeds the critical stress, Sa- The critical stress is defined as... 

Mechanosensitive ion channels can be looked at as membrane-embedded mechano-electrical switches. They play a critical role in transducing physical stresses at the cell membrane (e.g. lipid bilayer deformations) into an electrochemical response. Two types of stretch-activated channels have been reported the mechanosensitive channels of large conductance (MscL) and mechanosensitive channels of small conductance (MscS). 

Critical for predictivity in a recent comprehensive study was the number and choice of parameters measured [4]. Early, sublethal effects on cell proliferation, cell morphology and mitochondria occurred consistently and ubiquitously with toxicity and when used collectively were most diagnostic. It is noteworthy that the toxicity of many drugs is attributable to various mitochondrial targets, including oxidative phosphorylation, fatty acid oxidation, Krebs cycling, membrane transport, permeability transition pore, proliferation and oxidative stress (Table 14.4). 

Based on the authors experience, membrane fracture frequently occurs during events when membrane is dried out the in-plane hygrothermal stress is a critical driving force in membrane mechanical failure. The in-plane hygrothermal stress can be lowered by reducing the swelling/shrinkage ratio of the membrane, i.e., the dimensional instability of the membrane. 

Although simple, the use of bubble aeration in animal cell cultivation requires the solution of certain technological challenges for its implementation, since one of the most characteristic features of animal cells is their low resistance to mechanical stresses. Cell membranes have a mechanical resistance that is much lower than that of microbial cell walls. According to Castilho and Anspach (2003), shear stresses in the order of 60 Pa are critical for cell death. 

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