Trigger mechanisms

Surface defects, if sufficiently severe, may result in failure by themselves. More commonly, they act as triggering mechanisms for other failure modes. For example, open laps or seams may lead to crevice corrosion or to concentration sites for ions that may induce stress-corrosion cracking. 

The triggering mechanism for the corrosion process was localized depassivation of the weld-metal surface. Depassivation (loss of the thin film of chromium oxides that protect stainless steels) can be caused by deposits or by microbial masses that cover the surface (see Chap. 4, Underdeposit Corrosion and Chap. 6, Biologically Influenced Corrosion ). Once depassivation occurred, the critical features in this case were the continuity, size, and orientation of the noble phase. The massive, uninterrupted network of the second phase (Figs. 15.2 and 15.21), coupled... 

It consists of a spring-loaded cut-off valve which is held open in the open position under normal conditions. Should the pressure deviate sufficiently, the diaphragm will move and disengage the trigger mechanism, releasing the latch on the valve, which will close under the force of the spring. 

In 1863, against Sobrero s wishes, Alfred Nobel (1833-1896), a Swedish chemist and fellow student of Pelouze, developed 0 the blasting cap, a triggering mechanism that could deliver a 0... 

Even though the iron atoms are separated in haemoglobin by about 25 A, communication between them is still able to occur and this has been postulated to involve a trigger mechanism (Perutz, 1971). The trigger is the movement of the proximal histidine as dioxygen binds to (or is released from) the Fe(n) and results in interconversion between the T and R structures. This movement causes a conformational change which is transmitted through the protein to the other iron sites. X-ray studies indicate that relative shifts of up to 6 A at subunit interfaces occur between the T and R states (Perutz, 1978). 

For the pumping system, seawater was pumped up from 9 m and collected in the appropriate bottles on the raft and returned to the shore clean laboratory for preservation and/or analysis. For the other four sampling devices, the sampler was lowered to 9 m, allowed to equilibrate for 10 min, closed by triggering mechanism activated by the Teflon messenger, raised to the surface, transferred into the container, transported back by boat and trucked back... 

When and how does the SRR process occur — a role for sleep Currently, it is not clear what triggers the SRR process and when SRR usually takes place. We can only entertain a couple of ideas at this stage. One conceivable triggering mechanism could be that conscious recall can initiate the SRR process. This is consistent with common experience, where the more frequently a particular event is recalled, the better and longer it will be remembered. Another triggering mechanism could be the subconscious reactivation of the brain network. This could most likely be achieved during sleep, because various sleep states are... 

These two qualitative concepts are not opposed to each other. For example, criticizing the first approach one could mention that the electrons in any molecule are socialized, while it is impossible to establish the exact sites of localization of the charge and unpaired electron. It is not necessary to suppose that a certain trigger mechanism except accumulation of a certain amount of energy in a certain chemical bond is required to start fragmentation. Anyway both theories are qualitative and their joint usage allows successful interpretation of the spectra of various organic compounds. 

Figure 13.7 The triggering mechanism for the T to R transition in haemoglobin. (From Voet and Voet, 2004. Reproduced with permission from John Wiley Sons., Inc.)...

The orchids single benefit from supplying this rich reward is, of course, pollination. To ensure that the orchid bees perform as desired, the plants have devised incredible strategies. There are trigger mechanisms that shoot a pollen packet at the bee with considerable force, knocking him down but ensuring that the packet sticks to his body. There are flowers constructed like the western-prairie fringed orchid, so that a bee picks up a compact mass of... 

Extensive laboratory-scale studies have been conducted to investigate the triggering mechanism for RPTs when LNG, liquefied petroleum gas (LPG), and liquid refrigerants contact a hot liquid (usually water). These studies are covered in Sections III and VII. The evidence seems overwhelming that RPTs in these cases result from superheating of the cold, volatile liquid to its superheat-limit temperature where prompt homogeneous nucleation occurs in a time period of a few microseconds. (The properties of a superheated liquid and the concept of homogeneous nucleation are reviewed briefly in Section IX.)... 

Shick, P. E. (1980). Ck>ncentration-gradient trigger mechanism for smelt-water explosions. 

Since Mova, the FDA has granted the 180-day exclusivity to the first generic applicant for 31 drug products. Table 5-1 categorizes these grants of exclusivity by the triggering mechanism (either by commercial marketing or the decision of a court) as of June 1, 2002. 

This same rotor-cap-thyristor approach can also be used in the inverter-diode-induction coil approach noted above as the triggering mechanism instead of using the traditional points. This approach would allow for the switching on and off of the inverter and coil circuits together and for a determined firing period or multiple periods. 

J.S. Long, D. Mienert, J. Trincardi, F. Urgeles, R. Vorren, T.O. Wilson, C. (2004b). Triggering mechanisms of slope instability processes and sediment failures on continental margins a geotechnical approach. Marine Geology, 213 (1-4), 291-321. 

Do not touch any part of a boobytrap without first examining il thoroughly. Locate all firing devices and their triggering mechanisms. 

Both the creation of high-energy interfaces and the triggering mechanism for release of the energy are unpredictable and difficult to control... 

Activation of the caspases requires the help of a number of cofactors that are also known as activators or adaptors. Different cofactors are involved depending on the trigger mechanism of caspase activation. A central function of the cofactors is to bring about aggregation and thus activation of the procaspases. This occurs by specific protein-protein interactions with the help of common structural motives. Examples of such motives are the death domains (DD), death effector domains (DED) and the caspase recruitment domains (CARD), which all have a similar structure of six a-heh-ces. 

In addition to these trigger mechanisms, which permit rapid switching between different states of the ion channel, there is also the possibility to modulate and regulate activity of ion channels on a long-term basis. This regulation is usually due to phosphorylation in the cytoplasmic part (see 16.4.2.1). 

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