Proximity acceleration, studies

A small bowel transit study can be used to evaluate intestinal propulsion and clearance, and the presence of Enterobacteriacea (Gram-negative bacilli) in the small bowel indicates delayed transit [111]. The wide normal variability, however, makes transit tests rather insensitive, and thus less useful clinically [126, 127], It is also a problem that accelerated and delayed transit may coexist in neuropathies and confuse the interpretation. Finally, as nutrients are mostly absorbed in the proximal small bowel, and the rate and pattern of transit vary along the intestine, segmental failure of transit is easily missed by global... 

In the intramolecular reactions studied by Bruice and Koshland and their co-workers, proximity effects (reduction in kinetic order and elimination of unfavourable ground state conformations) and orientation effects might give rate accelerations of 10 -10 . Hence, these effects can by themselves account for the enhancements seen in most intramolecular reactions. However, a factor of 10 -10 is less than the rate acceleration calculated for many enzyme reactions and certain intramolecular reactions, for example, hydrolysis of benzalde-hyde disalicyl acetal (3 X 10 ) (Anderson and Fife, 1973) and the lactonization reaction of[l] (10 ) where a trimethyl lock has been built into the system. If hydrolysis of tetramethylsuccinanilic acid (Higuchi et al., 1966) represents a steric compression effect (10 rate acceleration), then proximity, orientation, and steric compression... 

The environmental factors that tend to accelerate metal loss include high humidity, high temperature and proximity to the ocean, extended periods of wetness and the presence of pollutants in the atmosphere. The small amount of carbon dioxide normally present in the air neither initiates nor accelerates corrosion. Vernon [57] was the first to study the corrosion rate of steel coupons in the presence of well-defined atmospheres. Atmospheric gases such as CO2, SO2, NO2, HCl, etc. after getting dissolved in the moisture layer on the metal surface, these gases result in a number of ions and ionic species like H", CF, COa , NOa , S04 , etc. They measured corrosion rate was as a function of time, relative humidity and... 

The simultaneity of chemists collective acceptance of the StahUan theory of an order of chemical composition and their new interest in and classification of the compound proximate principles of plants is a coincidence that had important consequences. Stahl s theory reinforced a continuous development of chemists analytical practice, which in the decades before had been spurred mainly by chemists attempt to reconcile their analytical and pharmaceutical objectives. By the middle of the century, the theory of a graduated order of chemical composition lent a clear and distinctive voice to these earlier attempts. It was an important and new condition for the acceleration of an ontological shift, which may be easily overlooked when historical studies concentrate exclusively on events taking place in the laboratory. But there was a further condition, external to developments in the chemical laboratory, which contributed to this accelerated ontological shift. This third condition will be examined in detail in the next section. 

The specimens (absorbers) consisted of 25-40 pm thick foils. Due to the higher neutron embrittlement and ageing sensitivity of VVER 440 (V-230) nuclear reactors, our study focused on the Russian 15Kh2MFA steel used in this older VVER-440 reactor type. The samples were subjected for one, two and three years to a neutron fluence ranging from 7.8 x 10 m to 2.5 x 10 " m . Taking into account the fact that the irradiation of the specimens was enhanced by their close proximity to the reactor core (leading to an accelerating factor of about 10), radiation treatment of the specimens after three years was equivalent to about 30 years in the real pressure vessel (the projected lifetime of VVER-440 V-230 reactors). More about this study can be found in [194],... 

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