The phrase "a second population of" is correct and usable in written English.
It can be used when referring to an additional group or set of individuals within a larger context, often in scientific or demographic discussions.
Example: "In our study, we identified a second population of bacteria that exhibited resistance to the antibiotic."
Alternatives: "an additional group of" or "a different set of".
A second population of around 400 mountain gorillas live in Uganda's Bwindi Impenetrable national park.
However, the 450 nm filters reveal a second population of associated heparin.
Furthermore, the presence of a second population of voids was concluded to strongly affect the fracture strain of the high strength regions of the welds.
Another extraordinary chapter in the saga was written last year, when a second population of the big ugly fish turned up some 10,000 kilometers away in Indonesia.
Application of transverse stretching to these films possessing semicrystalline structure gradually destroys the crystalline structure oriented in MD during this realignment while establishing a second population of oriented but poorly ordered crystallites in TD.
Once a critical void volume fraction is attained, final failure occurs by the fracture or decohesion of dispersoids from the matrix, initiating a second population of nanoscale voids, which interlinks the larger voids.
Contributions to failure anisotropy are identified as: (i) anisotropic initial void shape and growth; (ii) plastic behaviour including isotropic/kinematic hardening and plastic anisotropy; and (iii) nucleation at a second population of second-phase particles leading to coalescence via narrow crack regions.
In the present work, the production of high solid content latexes by emulsion copolymerization of styrene and butyl acrylate was studied in a semi-batch process in which the nucleation of a second population of particles is promoted by the instantaneous (shot) feeding of an additional charge of emulsifiers.
There is, however, a second population of regulatory T-cells that develops in the thymus [38].
These nuclei disappeared with time whereas a second population, of a smaller size, was then observed (Fig. 1b).
Similar analyses were performed for a second population of 20 healthy, overweight older subjects to verify associations found in population I.
