Aging in confined systems

FIGURE 5.16 Enthalpy recovery results for o-terphenyl aged at Tj — 11°C in (a) bulk state and (b) confined in an 11.6-nm pore diameter controlled pore glass material showing much smaller buildup of enthalpy overshoot upon aging of the confined material. Originally, similar data were interpreted [McKenna et al. [1992] to imply reduced aging in confined systems. (Data from Simon et al. [2002].)... 

Helium ages in confined groundwater systems are frequently greater than the corresponding hydraulic ages (section 2.10). Some examples include... 

Groundwater in unconfined systems receives recharge over the entire surface and, hence, is expected to have a recent age (section 10.4). If a well included in a model of an unconfined system reveals an absence of tritium, the model has to be modified to include a confined aquifer beside the unconfined one (Fig. 3.14). Water in a confined aquifer is expected to have the same age or reveal a certain age increase downflow. However, if the age varies suddenly between adjacent wells, for example, gets younger in the downflow direction, the connectivity assumption is disproved (Fig. 3.13). 

Acne and psoriasis Dermatologic problems such as acne and psoriasis are effectively treated with retinoic acid or its derivatives (see Figure 28.21). Mild cases of acne, Darier disease, and skri aging are treated with topical application of tretinoin (all trans retinoic acid), as well as benzoyl peroxide and antibiotics. [Note Tretinoin is too toxic for systemic administration and is confined to topical application.] In patients with severe recalcitrant cystic acre... 

Andrews et al. (1984) calculated flow velocities of 0.7-4 m/year for the confined Bunter sandstone groundwater system in eastern England. Hence, along the 20-km down-gradient flow in the study area the water should attain a hydraulic age of up to 80,000 years, whereas the corresponding helium age is 300,000 years. 

There are two distinct types of GSH-S deficiency, both associated with mild chronic hemolysis in one type, hemolysis is the only clinical manifestation. In the other, the major clinical features are mental retardation, severe generalized muscle weakness, tremors, incoordination, hemolytic anemia, and metabolic acidosis. This second and much more severe type of GSH-S deficiency is also known as 5-oxopro-linurta or pyroglutamic aciduria. The difference in severity of these disorders reflects the fact that in the mild form, GSH-S deficiency is confined to the RBCs because in this disorder the GSH-S is unstable. GSH-S activity is present in adequate quantity in young RBCs, but it rapidly declines as the cells age, because the cells are unable to synthesize new molecules of GHS-S. Other cells of the body that have nuclei and ribosomes can compensate for accelerated denaturation of GSH-S by synthesizing more. On the other hand, in the severe systemic form of GSH-S deficiency, aE cells of the body have low activities of GSH-S because they cannot form this enzyme in adequate amounts. In both types of GSH-S deficiency, RBCs exhibit notable reduction in GSH concentration. 

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