Weathering slowing

Under the natural conditions of weathering, slow oxidation of coal occtrrs with the formation of carbon suboxide and no, or very little, carbon dioxide is generated (Davidson, 1990). The heat release accompar ing coal oxidation to the polymerized substance can be described as... 

Under natural conditions the rates of dissolution of most minerals are too slow to depend on mass transfer of the reactants or products in the aqueous phase. This restricts the case to one either of weathering reactions where the rate-controlling mechanism is the mass transfer of reactants and products in the soHd phase, or of reactions controlled by a surface process and the related detachment process of reactants. 

The primary inconvenience is the relative slowness and lack of comfort, especially during days of inclement weather. Many millions of Americans live gi eat distances from where they work. Some might consider bicycling five miles to work each day, but few live that near to work. The typical 20-or-30-mile commute makes bicycling an unrealistic option for most people. And for those who do live close to work, few are willing to brave the elements to bicycle year around. Ram, snow, ice, high winds, extreme cold, and extreme heat that are minor inconveniences in a vehicle become major inconveniences on a bicycle. Thus, for backup, bicycle riders usually must own a vehicle for had weather days, or have access to convenient mass transit. 

Stanners have designed a test rig (Fig. 19.12) which provides results that can be correlated with actual atmospheric exposure data. The rig has been designed to investigate a wide range of alloying elements in a development programme on slow-weathering steels for which it was essential to have a rapid, reliable and reproducible test that incorporated the specific atmospheric factors responsible for rust formation. 

Hypothyroid myopathy occurs in about 30% of patients with hypothyroidism irrespective of its cause. Muscle pain, cramps, and stiffness may be seen, and are often exacerbated by cold weather. Pseudomyotonic features of delayed muscle contraction and relaxation are common. Myoedema (the mounding phenomenon) is due to the painless, electrically silent contracture produced on direct percussion. Muscle biopsy often shows a predominance of type 1 (slow-twitch) fibers, again analogous to that seen in experimental hypothyroidism (Figure 22). Muscle hypertrophy with weakness and slowness of movement occurs in the Debre-Semelaigne syndrome seen in severely hypothyroid children, and Hoffman s syndrome is a similar condition seen in adults with hypothyroidism, but is also accompanied by painful spasms. 

Weathering limited potential transport processes greater than weathering supply. Transport limited supply by weathering greater than the capacity of transport processes to remove material (until weathering is slowed by feedback). 

Blister agents such as distilled mustard (HD) and nitrogen mustard (HN) have a slow rate of action and might be persistence for three days to one week in warm weather and for some weeks in cold weather, while lewisite (L) and mustard/lewisite (HL) have a quick rate of action and would be persistent for one to three days during summer and for weeks during winter. Route of entry for these blister agents would be nearly the same eyes, lungs, and skin for vapor or aerosol, but for liquid, the points of entry would be the eyes and skin for HD and HN and eyes, skin, and mouth for L and HL. 

GD is more neurologically active than GA and GB. A dosage of 0.01 mg/kg (ingestion or skin absorption) may bring death within 1 minute. Since the body s ability to detoxify GD is very slow, it tends to accumulate in the body. Because it persists 1 to 2 days under moderate weather conditions, casualties through dose accumulation are common. 

The case of liquids is simpler than weathering in that it is essentially a two agent situation, liquid and temperature. As described in Sections 4.12.3 and 6.6.1, the rate of attack may be governed by the rate of diffusion of the liquid into the material, which may be slow in relation to the time scale of an accelerated test. Also, it is necessary to consider that there may be physical change (swelling) of the polymer as well as chemical degradation. 

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