Healing mechanism

Fig. 1.85 Oxidation of high-purity iron in oxygen at differing pressures. All figures on curves are in N m . At 1-3 x 10 tol-3 x 10 N/m torr the rate is controlled by the impact of molecular oxygen at I - 3 x 10 N/m torr the initial rate of oxidation is sufficiently high to give void precipitation and the rate decreases with pressure increasing to l-3N/m at pressures greater than this the crack-heal mechanism becomes operative and the rate again increases with pressure (after Hussey and Cohen...

Fig. 1.86 Stills from a scanning electron microscope study by time-lapse photography of iron oxidation showing the results of the crack-heal mechanism. Left, Immsl/tm right, 1 mm 0-5 /tm (courtesy Central Electricity Research Laboratories)...

Most peptic ulcers occur in the presence of acid and pepsin when HP, NSAIDs, or other factors disrupt normal mucosal defense and healing mechanisms. Acid is an independent factor that contributes to disruption of mucosal integrity. Increased acid secretion has been observed in patients with DU and may result from HP infection. Patients with GU usually have normal or reduced rates of acid secretion. 

Currently stem cells are the focus of a broad and burgeoning area of science aimed at marshaling their generative powers into new treatments, especially for degenerative disorders such as stroke, Parkinson s disease, and spinal-cord injury. These disorders are so destructive that the affected tissue generally cannot be repaired by the body s normal healing mechanisms. 

A highly relevant question is whether the goal should be to operate at the level of the single component or not. In order to minimize the risk of device failure the incorporation of some redundancy or repair procedures appears unavoidable, as in biological processes, so that it will be necessary to develop suitable addressing and detection procedures, error-checking and self-healing mechanisms for multidevice arrays. 

In other words, they have a self-healing mechanism. One major characteristics of supra-molecular structures is this capability for self-processes. There are processes that occur spontaneously, but they don t occur for covalent bonds at normal temperatures and pressures because they are too stable for that. You may in this respect consider molecular chemistry as stable chemistry or fixed-structure chemistry, and supramolecular chemistry as fluid chemistry. The term fluid here means that the structures can be arranged and rearranged, assembled and disassembled depending on the surroundings. Adaptation is another important characteristics of supramolecular systems. A molecular structure, as far as connectivity and gross change is concerned, is very stable, not influenced so much by the medium. A supramolecular structure can, in principle, adapt to the medium. 

Figure 1.52 Self-healing mechanism ofTa capacitors.

Q. Ludovic, R. Francis, G. Alain, T. Flenri, and L. Caroline, Self-healing mechanisms of a SiC fiber reinforced multi-layered ceramic matrix composite in high pressure steam environments, J. Eur. Ceram. Soc. 27[4], 2085-2094(2007). 

If a double layer is deformed by any kind of stress, which causes a reduction of density of surfactant molecules, this area has a higher surface tension (and higher energy). The system tries to compensate by a) migration of surfactant molecules from the bulk liquid into the area and b) shift of molecules from the double layer into the region. By this means, the system stabilises itself This self-healing mechanism is also known as the Marangony-Effect" ... 

Zheng P, McCarthy TJ (2012) A Surprise from 1954 siloxane equilibration is a simple, robust, and obvious polymer self-healing mechanism. J Am Chem Soc 134 2024... 

The oxide film grown in this process has a thickness of 0.5 pm. It is a film of a zinc oxide/hydroxide containing different chromium oxides (CrO(OH), Cr20j, Cr205, CrOj) and zinc chromate (ZnCrO ). The chromate ions are rather mobile. If a zinc layer on a steel substrate gets a scratch somewhere on the zinc, the chromate will diffuse to this scratch and repassivate the surface (the self-healing mechanism). ... 

Precaution Avoid laalized healing mechanism/units Storage Store in a cool, shaded, well-ventilated and dry area away from direct sources of heat and sunlight allow to warm to 50 C until a uniform prod, is obtained... 

Fig. 11 Proposed healing mechanism for D-A supported blends of oligomers. (Adapted with permission from [78], copyright 2014 RSC)...

Aramaki K. Self-healing mechanism of an organosiloxane polymer film containing sodium silicate and cerium (111) nitrate for corrosion of scratched zinc surface in 0.5 MNaCl. Corrosion Science, 44(7), 1621-1632 (2002). 

It is interesting to note that healing of the CP-PSMP composites is quite repeatable. From Figure 6.23, it can be seen that for five fiacturefhealing cycles, the proposed CTH healing mechanism as tested through CP-PSMP specimens is reasonably repeatable, for all three CP contents. 

Voyiadjis, G., Shojaei, A., Li, G., and Kattan, P.I. (2012) Continuum damage-healing mechanics with introduction to new healing variables. International Journal of Damage Mechanics, 21, 391-414. 

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