The phrase "a small fraction in" is correct and usable in written English.
It can be used when referring to a minor part or percentage of something within a larger context.
Example: "A small fraction in the overall population supports the new policy."
Alternatives: "a tiny portion of" or "a minor segment in".
Most of the labour force is employed in services and industry, with a small fraction in agriculture.
About 26,000 far-right extremists are known to the government, only a small fraction in a population of 82 million.
The system lets down the vast majority of young trainees who are allowed to commence an academic career, as it can only accommodate a small fraction (in the UK, about 4% of all science PhDs).
While a majority of the money collected at the event goes to the San Francisco AIDS Foundation itself, only a small fraction in recent years has actually gone to those other local H.I.V./AIDS charities.
It was found that CPE was incorporated in the copolymers primarily in the form of isolated cis-1,3 ring units, along with a small fraction in the form of isolated cis-1,2 ring units.
The identification of these leukemic initiating cells was based on differential expression of cell surface markers CD34 and CD38 where only CD34+/CD38- AML cells could give rise to leukemic growth in severe combined immodeficiency (SCID) mice even though they represented a small fraction in the total leukemic population.
It composes about 18.2 ppm of air by volume (this is about the same as the molecular or mole fraction), and a smaller fraction in Earth's crust.
SOD2 is localized to the mitochondrial matrix, while SOD1 is mainly cytosolic with a smaller fraction in the mitochondrial intermembrane space.
Interestingly, Lethe, Pbrm1 Convergent, Scripture 16,612 and Scripture 60,588 were found mostly on the chromatin, with a smaller fraction in the nucleus.
As shown in Fig. 6, consistent with the reported cell cycle analysis of 1s/2s cells, 1s/2s cells without EdU were predominantly present in G2 phase with a smaller fraction in G0/G1.
