The phrase "are at the maximum level" is correct and usable in written English.
It can be used to indicate that something has reached its highest point or capacity.
Example: "The battery levels are at the maximum level, ensuring that the device will run for hours without needing a recharge."
Alternatives: "are at full capacity" or "have reached the peak level."
Claudio Ranieri says his emotions were at "the maximum level" after Leicester were crowned Premier League champions.
In the Nash model, the payoff of the thermal power plant is at the maximum level and the payoff of the renewable power plant is at the minimum level.
Usually the sericin content of the cocoon shell is at the maximum level at the outside layer 1 becoming progressively lower at the middle layers 2 and 3 and the absolute minimum at the inside layer 4 (Table 6).
All operations are, at the maximum possible level, default-oriented, thus hiding behind scenes their complexity (e.g. definition of non-obvious parameters).
"We are using other facilities and in the next couple of weeks we will define a programme to be more specific on that, to see what is best time to shut down and improve things that are not at the maximum level at the moment," he said.
Consequently, the pits on the cell surface are present at the maximum level (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$\bar n_0$$\end{document} ).
It is also of significance that food intake was highest at the maximum level of complementation.
In addition, STAT5B activity is mostly regulated by its phosphorylation status and this appears to be already at the maximum level at the end of pregnancy and no further increases were observed in lactating bovine mammary.
For qualitative comparison of morphology, each genotype was imaged at the maximum level of brightness while avoiding saturation.
