Deterioration biological, types

In spite of these many limitations, there are a number of approaches that have been successfully used for certain deteriorative reactions (Table XIII). The most obvious approach is to determine the biochemical or biological activity of a protein when the protein has such a property. The difficulty in these determinations is that the deteriorated protein may have a biochemical activity that is changed or attenuated without loss of activity. In such a hypothetically modified protein, a biochemical determination might show that there is only 50% activity present. However, such a determination could not differentiate between complete inactivation of 50% of the molecules or a 50% reduction in activity of 100% of the molecules by an attenuation rather than an inactivation. A different test would be necessary in order to "count" the number of biochemically active molecules. For this purpose, the enzyme chemist sometimes uses an active site titrant, which is a type of an affinity reagent (16). 

Table II. Types of Biological Deterioration of Wood and the Organisms Responsible...

Drugs sometimes have quite complicated chemical structures and are, by definition, biologically active compounds. It should not, therefore, come as a surprise that these reactive molecules undergo chemical reactions that result in their decomposition and deterioration, and that these processes begin as soon as the drug is synthesised or the medicine is formulated. Decomposition reactions of this type lead to, at best, drugs and medicines that are less active than intended (i.e. of low efficacy)-, in the worst-case scenario, decomposition can lead to drugs that are actually toxic to the patient. This is clearly bad news to all except lawyers, so the processes of decomposition and deterioration must be understood in order to minimise the risk to patients. 

Batch process stop feed because the membrane performance has deteriorated or because the target concentrations or volumes of permeate or retentate have been achieved. Deteriorated membrane performance can be (1) because of a buildup of particulates or biological deposits (this can be corrected by backflushing with permeate or cleaning with detergents, acids, or bases) or (2) because the membrane needs to be replaced (the life of a membrane is one or two to ten years, depending on the operating conditions and the type of membrane). See Table 16.32. 

Discharge of wastewaters into surface waters is connected with a very serious type of deterioration of the quality of surface waters — exitrophiza-tion. This is a series of natural, or artificially induced biological processes caused by an increase in inorganic nutrients in surface waters. 

Techniques for Suppressing Deterioration. The methods that might be chosen to suppress deterioration depend on the type of deterioration that is taking place. The nature of biological deterioration has been amply covered in previous chapters. 

Chemical composition makes certain cell types (e.g., ray parenchyma cells (22) and parts of cells such as pit membranes (23) more susceptible to biological attack. Hedges et al. (24) and Barbour and Leney (25) have shown that the degree of deterioration is often closely related to the topochemistry of individual cell types and parts of cells. 

Because ISE responses do not depend on any type of ion current or flux, they are much less affected by adsorption of contaminants onto the sensor membrane than most other electrochemical and optical sensors. As long as adsorbed contaminants do not completely cover the ISE membrane, they have no effect on the measured response. However, in contrast to sensors based on solid sensing phases, such as metals in voltammetric sensors or inorganic salts in solid-state ISEs, extraction of hydrophobic sample components into the hydrophobic sensing membranes of ionophore-doped ISEs can result in the deterioration of the ISE selectivity. This is of particular concern in the case of long-term measurements in biological samples. 

Answer Cooling of the biological shield will prolong its effectiveness by slowing down the drying of concrete in Ihe concrete-iron ore type of shield or the deterioration of the masonite in the iron-masonite type of shield. 

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