Environmental factors, light

All the environmental factors, light, water, macro- and micronutrients, pH of the soil, temperature, and probably others have still been insufficiently investigated. There was considerable interest in this type of research in the 19th century mostly the alkaloids were isolated as salts of silicotungstic or phosphomolybdic acids. Because these form different complex salts with alkaloids encountered in the plant, it must be assumed ipso facto that the obtained data were only crude approximations. 

Environmental factors such as severe hailstorms and human errors such as impact by aircraft service equipment also cause in-service damage to bonded assemblies. Bonded honeycomb sandwich assemblies are particularly prone to such damage because of their customary use as lightly loaded fairings and flight control surfaces and subsequent thin facesheets and relative fragility. 

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. 

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. 

The purpose of stability testing is to assess the effects of temperature, humidity, light, and other environmental factors on the quality of a drug substance or product. The data produced are used to establish storage conditions, retest periods, shelf loss, and to justify overages included in products for stability reasons. The most useful equation relating temperature and reaction rate is the Arrhenius equation. This equation (27) may be integrated and rewritten as Eqs. (31) and (32). 

C02 is not the only factor involved in photosynthesis, so that for its use, other factors must be at levels that do not limit the process. Light, temperature, amount of available nutrients and the relative humidity are other environmental factors affecting photosynthetic activity. 

The attenuation of an optical fibre results from physical phenomena either occurring within the fibre or coming from the environment. This is the sum of light lost by scattering in the fibre, absorption by the fibre materials, leakage of light out of the core due to environmental factors (e.g. microbends). Scattering and absorption losses dominate in every fibre. 

In general, unless a local reservoir (i.e., intermediate host that may or may not be affected by the virus) is established, pathogens are easily killed by unfavorable environmental factors such as fluctuations in temperature, humidity, food sources, or ultraviolet light. For this reason, their persistency is generally limited to days. However, freeze-dried pathogens can remain in a preserved state almost indefinitely and are reactivated when exposed to moisture. 

Numerous nitrogen-free toxins occur in plants. As discussed in the introduction to this Chapter, many of these compounds are believed to be for the protection of the plant from herbivory. However, because there is such a diversity in plant compounds, there are other functions they serve, e.g., insect attractants for pollination, and protection against environmental factors, such as UV light, low or high temperatures, drought, etc. 

Accuracy of tolerance lists is further complicated by the fact that data are often available from only one locality or from a single experimental laboratory where one set of environmental factors interact with the pollutant reaction. Differences in plant age, variety, rate of growth, light exposure, climatic conditions, nutrition and other factors can induce significant variation in response to a particular pollutant. 

---