The phrase "are of main concern" is correct and usable in written English.
It can be used when discussing issues or topics that are particularly important or troubling.
Example: "The environmental impacts of climate change are of main concern to scientists and policymakers alike."
Alternatives: "are a primary concern" or "are of significant concern".
Safety criteria are of main concern issues in the entire nuclear research reactor lifetime to satisfy the defense in depth criteria.
The results are consistent with previous findings that a single-input model is not sufficient to study the transmission of vibration to the seat back in the horizontal directions, while for the transmission of vertical vibration a single-input model is probably sufficient, especially when low frequencies are of main concern.
The unique features of direct fluidized-bed coking of oil sands enable it to be effectively used in the separation of bitumen from oil sands, where the fluidization characteristics of burned oil sands particles are of main concern.
It is generally accepted that the cost and time are of main concerns in any tunnelling project as these two factors influence greatly on the economic viability of the hydropower projects.
The circularization with short concrete segments is more effective for hollow specimens than the circularization with full length concrete segments when the ductility is of main concern.
Thus, the algorithm is applicable in final stages of the structure refinement, when the quality of the results is of main concern.
In the latter case the prevention of thermal degradation of bottoms is of main concern, i.e. the bottom temperature needs to be kept as low as possible.
This study provides beneficial information in assisting subsequent design of bolted joints where behavior under impact loading is of main concern.
The absence of high-temperature additive in drilling mud was of main concern where the drilling mud could not sustain its rheological properties.
