This arises because it is necessary to have a certain concentration of nitrogen in the available soil pool (freely-exchangeable plus solution nitrogen) from which the crop can take up the nitrogen it needs, and concurrently the available soil pool will lose nitrogen at a rate controlled by various biophysical processes.
This showed that the UDP concentration present in the polymerization assay has to reach a certain concentration limit which seems to be above 4 mM in order to be an inhibitor of PmHS2 activity.
The decrease in the percentage removal of atrazine can be explained by the fact that the AgNPs beads had limited active sites, which would have become saturated above a certain concentration.
Previous studies have shown that, at a certain concentration range, Ca and Si ions can stimulate cell proliferation and differentiation [ 32, 37].
Our results agree well with the work of Kymakis et al. [17] who have shown that above a certain concentration of SWNTs, the semiconducting response of the composite and the efficiency of photovoltaic devices deteriorate.
Preclinical toxicological studies on animals (rats and dogs) have shown that above a certain concentration level C-52 causes secondary effects such as neutropenia and gastrointestinal problems but not neurotoxicity.
These results agree with the majority of the scientific literature on the subject of anaerobic LAS biodegradation, it has been found that over a certain concentration LAS can become inhibitory to biogas production; this threshold has been shown to be as low as just 20 ppm [1].
It is suggested that 26-nm ZnO NPs appeared to have the highest toxicity, while a certain concentration of nano-ZnO with the average sizes of 62 nm and 90 nm had the same influence on the membrane integrity and cell cycle of Caco-2.
It may be advantageous to apply somewhat more severe pretreatment to generate slightly more sugar degradation products, which, up to a certain concentration, have been shown to increase the ethanol yield [ 32, 36].
It was found that the MPOF probe only have a response to nitrites in a certain concentration of sulfuric acid solution.
