Exposure length

Spanish Hemp Workers. Data collected on hemp workers have been offered in support of chronic respiratory effects associated with cotton dust exposure. Historically, hemp workers constituted the first group to call medical attention to their respiratory effects (27). More recent studies done on hemp workers, however, suggest similar limitations of methodology as mentioned above. The recruitment of subjects leaves much perplexity about the representative character of the group, when the source population is not accounted or even remotely described (28, 29, 30). The exposure length is not assessed (some of the workers have less than two years tenure) and/or the status of "retirement" is used uncritically as an index of exposure (29,... 

The onset of asbestosis is dependent on intensity of dust exposure, length of exposure. 

Wang Z, Zhang W-Q, Safe S, et al. 1997. Mutation frequency and spectrum in relation to dose and exposure length in coal tar carcinogenesis. Proc Am Assoc Cancer Res 38 461. 

Exposure Length Tensile Strength, MPa Break Elongation, %... 

Equation 1.53 gives us a very quick estimate of the rod temperature and how it varies with exposure length. For example, if a is much greater than unity (i.e., long Lj section and high liquid heat transfer coefficient compared to gas coefficient), the rod temperature is then very near T. Taking the rod temperature to be represented by Eq. 1.53, the rate of heat transfer is readily calculated from Eq. 1.52 by replacing T ... 

Thus for a given temperature difference and a constant rod diameter, the rate of heat transfer can be enhanced by either increasing the exposure length Lj or by increasing the heat transfer rate by stirring the solvent. However, these conclusions are tied to the assumption of constant rod temperature, which becomes tenuous as atmospheric exposure is increased. 

At peripheral nerves the reduction in sodium influx leads to a decrement in action potential formation and propagation. In animal studies a reduction in action potential by 50% is necessary for observable loss of neuronal function and exposure length of the nerve fiber is important in conduction blockade [41]. At central neuraxial administration of LA similar mechanisms to those previously discussed occur at the level of the spinal nerve roots. Additionally, at the dorsal horn, LA possibly exert action at sodium and potassium chaimels in ventral and dorsal horn neurons [41]. Furthermore local anesthetics may exert action at neurotransmitters or neuropeptides such as substance P or y-aminobutyric acid (GABA) by either directly binding to receptors or by altering local pharmacokinetics of endogenous agonists [41 ]. 

The SPME fiber was fully exposed (1.0 cm), approximately half exposed (0.5 cm), approximately one-fourth exposed (0.25 cm), and approximately one-eighth exposed (0.12cm) to the headspace gas (SH-SPME sampling) and the nitrogen gas stream (DH-SPME), respectively. Exposure length was controlled by creating three additional notches in the SPME holder [13]. 

The increased exposure to the reservo/r results from the long horizontal sections which can be attained (between 500m and 1000m horizontal section is now common). Because the productivity index is a function of the length of reservoir drained by a well, horizontal wells can give higher productivities in laterally extensive reservoirs. As an initial estimate of the potential benefit of horizontal wells, one can use a rough rule of thumb, the... 

A constant force is applied to an ideal elastomer, assumed to be a perfect network. At an initial temperature Tj the length of the sample is Ij. The temperature is raised to Tf and the final length is If. Which is larger Ij or If (remember F is a constant and Tf > Tj) Suppose a wheel were constructed with spokes of this same elastomer. From the viewpoint of an observer, the spokes are heated near the 3 o clock position-say, by exposure to sunlight-while other spokes are shaded. Assuming the torque produced can overcome any friction at the axle, would the observer see the wheel turn clockwise or counterclockwise How would this experiment contrast, in magnitude and direction, with an experiment using metal spokes ... 

Isolation of radioactive wastes for long periods to allow adequate decay is sought by the use of multiple barriers. These include the waste form itself, the primary containers made of resistant materials, overpacks as secondary layers, buffer materials, concrete vaults, and finally the host rock or sod. Barriers limit water access to the waste and minimize contamination of water suppHes. The length of time wastes must remain secure is dependent on the regulatory limit of the maximum radiation exposure of individuals in the vicinity of the disposal site. 

In view of the above, aniline should be handled in areas with adequate ventilation and skin exposure should be avoided by wearing the proper safety equipment. Recommended personal protective equipment includes hard hat with brim, chemical safety goggles, hiU length face shield, mbber gaundet gloves, mbber apron, and mbber safety shoes or mbber boots worn over leather shoes. 

Nonoxide fibers, such as carbides, nitrides, and carbons, are produced by high temperature chemical processes that often result in fiber lengths shorter than those of oxide fibers. Mechanical properties such as high elastic modulus and tensile strength of these materials make them excellent as reinforcements for plastics, glass, metals, and ceramics. Because these products oxidize at high temperatures, they are primarily suited for use in vacuum or inert atmospheres, but may also be used for relatively short exposures in oxidizing atmospheres above 1000°C. 

A sealant s adhesion is commonly studied by 180 degree peel tests such as ASTM C794 or by tensHe/adhesion joints tests such as ASTM C719. The adhesion test protocol should simulate actual field conditions as closely as possible. Sealants often have good adhesion to dry substrates, but this adhesion may be quickly destroyed by water. Because most sealants are exposed to water over their lifetime, adhesion testing should include exposure to water for some length of time. ASTM C719 is one of the better tests to determine a sealant s adhesion durabHity as it exposes sealants to seven days of water immersion. 

---