Environmental factors environment

Hardman R (2006) A toxicologic review of quantum dots toxicity depends on physicochemical and environmental factors. Environ Health Perspect 114 165-172... 

Duffy PH, Leakey JE, Pipkin JL, Turturro A, Hart RW. The physiologic, neurologic, and behavioral effects of caloric restriction related to aging, disease, and environmental factors. Environ Res 1997 73 242-248. 

Pain expression is also influenced by environmental factors, such as cultural attitudes, attention, and stress. Fibromyalgia (FM), tension headaches, and irritable bowel syndrome are a few of the functional pain conditions influenced by environmental factors. Environment may sometimes confound elTorts to isolate genetic contributions in clinical studies, and these elfects should be kept in mind. 

The environment plays several roles in corrosion. It acts to complete the electrical circuit, ie, suppHes the ionic conduction path provide reactants for the cathodic process remove soluble reaction products from the metal surface and/or destabili2e or break down protective reaction products such as oxide films that are formed on the metal. Some important environmental factors include the oxygen concentration the pH of the electrolyte the temperature and the concentration of anions. 

In general, as the corrosiveness of the environment increases, the rate of crack growth also increases. Environmental factors constituting corrosiveness vary with the metal under consideration. 

Erosion-corrosion is a fairly complex failure mode influenced by both environmental factors and metal characteristics. Perhaps the most important environmental factor is velocity. A threshold velocity is often observed below which metal loss is negligible and above which metal loss increases as velocity increases. The threshold velocity varies with metal and environment combinations and other factors. 

Environments. Among the environmental factors that can shorten life under thermal fatigue conditions are surface decarburization, oxidation, and carburization. The last can be detrimental because it is likely to reduce both hot strength and ductility at the same time. The usual failure mechanism of heat-resistant alloy fixtures in carburizing furnaces is by thermal fatigue damage, evidenced by a prominent network of deep cracks. 

ISO 9001 is not specific on what is meant by working environment . ISO 9001 only applies to product and factors that affect the product therefore working environment means the environment in which work on product is carried out. If temperature, cleanliness, humidity, electromagnetic, and other environmental factors need to be controlled to ensure conforming product then their control provides a suitable working environment. 

If you cannot select suitable equipment for your current environment, you may need to control the environment in order to carry out the measurements. In such areas the environmental factors important to maintaining stable measurement should be monitored and the monitoring equipment calibrated. Chart recorders enable you to monitor conditions without having to be in constant attendance. The environment should be controlled in areas where calibration is carried out in order to provide stable conditions in which accurate and precise measurement can be taken. However, some modern equipment is so stable that environmental controls are unnecessary except in special circumstances. 

The rate of protonation may vary according to the structure of the light-emitter and the environment around the light emitter. In the case of chemiluminescence reactions in solutions, the hydrophobicity, permittivity (dielectric constant) and protogenic nature of the solvent are important environmental factors. In the case of bioluminescence involving a luciferase or photoprotein, the protein environment surrounding the light-emitter will be a crucial factor. 

In using fiber optics the designer is mainly concerned with a standardized material which has specific characteristics in terms of optical performance. Fiber optics made of plastics can be affected by exposure to the environment with deterioration of performance. Heat is an important environmental factor and the most likely cause of damage in optical applications. The heat can be generated by the light sources used. Some of the infrared generated by light sources can be removed with the use of appropriate filters. 

When animal cells are removed from the body, the cells can be maintained (or cultured) for prolonged periods, provided the cells are in an appropriate alternative environment. Environmental factors of importance for animal cell culture include the culture medium, substratum (or surface of the culture vessel), and temperature. The substratum (or surface) is a significant factor for those animal cells which grow attached to the surface of the culture container. A number of types of animal cells (such as lymphoid cells) grow in suspension. 

The possible effects of increased atmospheric CO2 on photosynthesis are reviewed by Goud-riaan and Ajtay (1979) and Rosenberg (1981). Increasing CO2 in a controlled environment (i.e., greenhouse) increases the assimilation rate of some plants, however, the anthropogenic fertilization of the atmosphere with CO2 is probably unable to induce much of this effect since most plants in natural ecosystems are growth limited by other environmental factors, notably light, temperature, water, and nutrients. 

Nevertheless, it should not be concluded that any substance with a degree greater than 100% creates an inflammable environment. There is an environmental factor that was not taken into account here, which is the quantity of substance handled, the ventilation rate of the premises and the vapourisation speed of the liquid. This last factor is recommended by regulations but there are few figures available. These values are determined in conditions that cannot be compared with each real condition and are related to substances of different natures that cannot allow any direct comparison. 

Carcinogenic agents include chemicals in the environment, such as aniline and benzene, which are associated with the development of bladder cancer and leukemia, respectively. Environmental factors, such as excessive sun exposure, also may result in cancer. Viruses, including the human papilloma virus and hepatitis B, maybe associated with the development of cancer. Some of the chemotherapy agents cause secondary cancers after therapy has been completed. Numerous factors may contribute to the development of cancer. 

Cataldo DA, Garland TR, Wildung RE, et al. 1980. Foliar absorption of transuranic elements Influence of physicochemical form and environmental factors. J Environ Qual 9(3) 364-369. 

Table 20.3 lists the reversible and irreversible processes that may be significant in the deep-well environment.3 The characteristics of the specific wastes and the environmental factors present in a well strongly influence which processes will occur and whether they will be irreversible. Irreversible reactions are particularly important. Waste rendered nontoxic through irreversible reactions may be considered permanently transformed into a nonhazardous state. A systematic discussion of mathematical modeling of groundwater chemical transport by reaction type is provided by Rubin.30... 

Transformation processes alter the chemical structure of a substance. In the deep-well environment, the transformation processes that may occur are largely determined by the conditions created by partition processes and the prevalent environmental factors. Transport processes do not need to be considered if transformation processes irreversibly change a hazardous waste to a nontoxic form. 

The previous chapter examined the geochemical processes that can occur in the deep-well environment. The type and outcome of reactions that will actually occur when a waste is injected, however, depend on its chemical characteristics and on injection-zone conditions. This chapter examines six major environmental factors that must be taken into consideration. 

The pH of a system greatly influences what chemical processes will occur in the deep-well environment. Directly or indirectly, pH also affects most of the other environmental factors. Table 20.12 summarizes the significance and some major effects of changes in pH on chemical processes and environmental factors in the deep-well environment. 

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