Processing at higher levels

The first reports on photovoltaic effects recorded for organic devices were based on single-layer devices discussed above, which were simply a semiconducting polymer sandwiched between two electrodes with different work functions (exciton dissociation takes place at the interface between the active layer and electrode) (e.g. [65-67]). Although, the devices could show fairly high Vqc of up to 1.7 V, the /sc values were very low, which resulted in very poor PCEs. A significant improvement was achieved by bringing 

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It was shown in laboratory studies that methanation activity increases with increasing nickel content of the catalyst but decreases with increasing catalyst particle size. Increasing the steam-to-gas ratio of the feed gas results in increased carbon monoxide shift conversion but does not affect the rate of methanation. Trace impurities in the process gas such as H2S and HCl poison the catalyst. The poisoning mechanism differs because the sulfur remains on the catalyst while the chloride does not. Hydrocarbons at low concentrations do not affect methanation activity significantly, and they reform into methane at higher levels, hydrocarbons inhibit methanation and can result in carbon deposition. A pore diffusion kinetic system was adopted which correlates the laboratory data and defines the rate of reaction. 

Extraneous constituents present in a synthetic reagent used in the chemical process can also end up as an impurity in the pharmaceutical agent. Such extraneous constituents may or may not react chemically during the synthesis of the desired pharmaceutical agent. Compounds that do not react chemically may be present at low levels in the final product and may be present at higher levels in... 

Plant hormones rarely act alone hormones interact to produce a final effect. According to Gaspar et al., Some responses of plants to auxins may be caused by increased ethylene synthesis in response to auxin treatment. At high ethylene concentrations, microtubule and microfibril orientation are altered, which results in decreased cell elongation and increased cell expansion. The role of ethylene is hard to understand because it effects vary with developmental stage and because low concentrations can promote (or sometimes inhibit) a process, whereas higher levels have the opposite effect [22]. 

The process by which there is an increase in the concentration of a chemical in the species at higher levels in the food chain. 

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