Irreversible failure

Selected compounds of these series were tested in an in vitro rat model of cerebral ischemia and proved to prevent the irreversible failure of synaptic activity induced by oxygen and glucose deficiency in the hippocampus, thus confirming that potent and selective A3 AR antagonists may substantially increase the tissue resistance to ischemic damage. 

Durability is the capability of a PEM fuel cell stack to resist permanent change in performance over time. A durability failure may not cause catastrophic failure in the fuel cell. However, this mode of failure will decrease the performance of the fuel cell. It also can involve irreversible failures, such as electrochemical surface area reduction, carbon corrosion, etc., and losses mainly related to ageing [12]. 

Failure of a nickel-cadmium battery can be classified into two general categories reversible and irreversible failure. When a battery fails to meet the specified performance requirements but can, by appropriate reconditioning, be brought back to an acceptable condition, it is considered to have suffered a reversible failure. Permanent or irreversible failure occurs when the battery cannot be returned to an acceptable performance level by reconditioning or any other means. 

Under compression or shear most polymers show qualitatively similar behaviour. However, under the application of tensile stress, two different defonnation processes after the yield point are known. Ductile polymers elongate in an irreversible process similar to flow, while brittle systems whiten due the fonnation of microvoids. These voids rapidly grow and lead to sample failure [50, 51]- The reason for these conspicuously different defonnation mechanisms are thought to be related to the local dynamics of the polymer chains and to the entanglement network density. 

It is necessary to estabUsh a criterion for microbial death when considering a sterilization process. With respect to the individual cell, the irreversible cessation of all vital functions such as growth, reproduction, and in the case of vimses, inabiUty to attach and infect, is a most suitable criterion. On a practical level, it is necessary to estabUsh test criteria that permit a conclusion without having to observe individual microbial cells. The failure to reproduce in a suitable medium after incubation at optimum conditions for some acceptable time period is traditionally accepted as satisfactory proof of microbial death and, consequentiy, stetihty. The appHcation of such a testing method is, for practical purposes, however, not considered possible. The cultured article caimot be retrieved for subsequent use and the size of many items totally precludes practical culturing techniques. In order to design acceptable test procedures, the kinetics and thermodynamics of the sterilization process must be understood. 

The total heat released is the sum of the entropy contribution plus the irreversible contribution. This heat is released inside the battery at the reaction site. Heat release is not a problem for low rate appHcations however, high rate batteries must make provisions for heat dissipation. Failure to accommodate heat can lead to thermal mnaway and other catastrophic situations. 

Determine whether a catastrophic failure of the ammonia storage tank could cause irreversible health impacts in a nearby neighborhood. 

There is another type of condition that results from exposure to high humidity. The alteration in electrical properties caused by moisture absorption in nylon and phenolics is reversible. When the moisture content is decreased, the properties of the materials recover to close to the original values. In some instances the exposure to moisture and electrical fields can cause irreversible damage that can lead to failure. 

Die neurological disorder associated with severe vitamin B12 deficiency is termed funicular myelitis. Vitamin B12 deficiency leads to disturbed choline-, phospholipid-, and nucleic-acid synthesis, resulting in spinal marrow damages. Disturbed myelin synthesis finally causes irreversible neurological failure. In addition, there are psychiatric disturbances (disturbed memory, apathy). 

Persistently high operating temperatures lead to irreversible changes in the structure of the steel and eventual failure. 

Iron(II) alkyl anions fFe(Por)R (R = Me, t-Bu) do not insert CO directly, but do upon one-electron oxidation to Fe(Por)R to give the acyl species Fe(Por)C(0)R, which can in turn be reduced to the iron(II) acyl Fe(Por)C(0)R]. This process competes with homolysis of Fe(Por)R, and the resulting iron(II) porphyrin is stabilized by formation of the carbonyl complex Fe(Por)(CO). Benzyl and phenyl iron(III) complexes do not insert CO, with the former undergoing decomposition and the latter forming a six-coordinate adduct, [Fe(Por)(Ph)(CO) upon reduction to iron(ll). The failure of Fe(Por)Ph to insert CO was attributed to the stronger Fe—C bond in the aryl complexes. The electrochemistry of the iron(lll) acyl complexes Fe(Por)C(0)R was investigated as part of this study, and showed two reversible reductions (to Fe(ll) and Fe(l) acyl complexes, formally) and one irreversible oxidation process."" ... 

Pathological observations indicate that lesions of the cardiovascular system can be a cause of death in patients with anaphylaxis [2], Myocardial lesions might be the anatomical basis for the irreversible cardiac failure occasionally associated with systemic anaphylaxis [3]. There is compelling evidence that the heart is directly and/or indirectly involved in several forms of anaphylaxis in man [1,4,5]. 

For drugs approved under accelerated approval regulations on the basis of a surrogate endpoint or an endpoint other than survival or irreversible morbidity, FDA may require a Phase IV study to confirm the drug s efficacy. Failure to show efficacy may result in withdrawal of approval. 

The NIOSH IDLH is defined by the NIOSH-OSHA Standard Completions Program only for the purpose of respirator selection and represents a maximum concentration from which, in the event of respiratory failure, one could escape within 30 min without experiencing any escape-impairing or irreversible health. 

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