Process action

These control functions prevent abnormal process actions that would jeopardize personnel safety, harm the environment, or damage equipment and/or property. 

Carrying out appropriate process action so that the situation does not escalate further. 

Knackstedt, L.A., Samimi, M.M., and Ettenberg, A., Evidence for opponent-process actions of intravenous cocaine and cocaethylene, Pharmacol. Biochem. Behav., 72, 931, 2002. 

A reaction quench is a system where an inhibiting substance (quench solution stored in a separate container vessel) can be quickly and effectively fed into the reactor via a pipe which is protected with appropriate isolation valves. This action is independent of other process actions that may be required. The reaction quench can be manually initiated or automatically when certain process parameters are exceeded. 

Information processing in the brain, therefore, includes electrochemical processes. Action potentials are electrical impulses, but the messages they carry are generally mediated by chemicals. These chemicals are known as neurotransmitters since they transmit messages between neurons as well as between neurons and muscles or glands. The following sidebar discusses neurotransmitters in more detail. 

Structural features met in some cellulases include an a,a barrel111 similar to that of glucoamylase (Fig. 2-29) and, in a cellobiohydrolase,101 a 5-nm-long tunnel into which the cellulose chains must enter. Ten well-defined subsites for glycosyl units are present in the tunnel.101 A feature associated with this tunnel is processive action, movement of the enzyme along the chain without dissociation,105 a phenomenon observed long ago for amylases (see Section 9) and often observed for enzymes acting on nucleic acids. 

Fe-S clusters in 862 multisubstrate, kinetics of 464,465 oligomeric 475,497 pacemaker 535—537 processive action 602 prochiral centers 478-481 proofreading 482... 

Still not fully understood is the processive action of kinesin.221 224 It is often assumed that this protein moves in a hand-over-hand fashion with the two heads binding alternatively to the microtubule. Some substantial reorganization of the peptide chain in the hinge region at the end of the neck is presumably involved.173 An alternative "inchworm" mechanism has been suggested.2203... 

Interlocks Some of these are provided for safety and are properly called safety interlocks. However, others are provided to avoid mistakes in processing the batch. When safety is not involved, terms such as permissives and process actions are sometimes used in lieu of interlocks. Some understand the term interlock to have a connection to safety (interlock will be subsequently defined as a protective response initiated on the detection of a process hazard). 

Process actions. These are designed to prevent process conditions that would unduly stress equipment (perhaps leading to minor damage), lead to off-specification product, and so on. Basically, the process actions address hazards whose consequences essentially lead to a monetary loss, possibly even a short plant shutdown. Although sometimes referred to as interlocks, process actions address situations that are not deemed to be process hazards. 

Implementation of process actions within process control systems is perfectly acceptable. Furthermore, it is also permissible (and probably advisable) for responsible operations personnel to be authorized to bypass or ignore a process action. Safety interlocks must be implemented within the separate safety interlock system. Bypassing or ignoring safety interlocks by operations personnel is simply not permitted. When this is necessary for actions such as verifying that the interlock continues to be functional, such situations must be infrequent and incorporated into the design of the interlock. 

Situations resulting in minor equipment damage that can be quickly repaired do not generally require a safety interlock however, a process action might be appropriate. 

Although safety interlocks can inappropriately initiate shutdowns, the process actions are usually the major source of problems. It is possible to configure so many process actions that it is not possible to operate the plant. 

Crude phosphoric acid obtained from the wet process (action of dilute sulfuric acid on phosphate rock) contains many impurities such as fluorine, metals, and... 

The toxicity associated with SM is quite profound. The Army s Chemical Defense Equipment Process Action Team estimated in 1994 that a 900 mg-min/m SM vapor exposure would be lethal in 2-10 min, based on animal studies (National Research Council Review, 1997). Fortunately, in the battlefield, lethality has been limited. Only 1-3% of exposed soldiers died from SM exposure after WWI, and mortality mostly was not a direct consequence of SM, but rather the indirect effect of secondary respiratory infections. The 1999 Material Safety Data Sheet, put out by the US Army Soldier and Biological Chemical Command, USA Edgewood Chemical Biological Center, has estimated the LD50 of a skin exposure to sullur mustard as lOOmg/kg. This roughly translates into as little as 7 ml of neat SM (i.e. 8.9 g) spread over the skin resulting in the death of a 80 kg adult (Department of the Army, MSDS, 1999). The cornea, of course, is more sensitive than the skin. Below we review three chief toxic effects of severe SM exposure to the cornea. 

Kinesin hydrolyzes ATP at a rate of approximately 80 molecules per second. Thus, given the step size of 80 A per molecule of ATP, kinesin moves along a microtubule at a speed of 6400 A per second. This rate is considerably slower than the maximum rate for myosin, which moves relative to actin at 80,000 A per second. Recall, however, that myosin movement depends on the independent action of hundreds of different head domains working along the same actin filament, whereas the movement of kinesin is driven by the processive action of kinesin head groups working in pairs. Muscle myosin evolved to maximize the speed of the motion, whereas kinesin functions to achieve steady, but slower, transport in one direction along a filament. 

Topoisomerase reactions have been shown to proceed via both distributive and processive modes (Wang and Liu, 1979). Distributive action involves the dissociation of the enzyme from the DNA after each catalytic cycle whereas processive action requires several catalytic cycles to occur before the enzyme dissociates. In the relaxation of supercoiled DNA, the appearance of fully relaxed products, while some supercoiled substrate still remains, indicates a processive mode. Alternatively, conversion of all supercoiled substrate to partially relaxed intermediates before the appearance of fully relaxed products indicates a distributive mode. 

For the construction of the PRIME environment (Subsect. 3.1.5) on top of the PDW, the NATURE process meta model [201] has also been embedded as an extension of the Core Ontology. The concepts of Contexts (EC, PC, CC) have been derived from the Process Action, while the process tracing concepts are children of Process Trace. Organizational elements like users, work groups, and companies have also been extended from the appropriate concepts. 

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