The phrase "are observed to exist" is correct and usable in written English.
It can be used in contexts where you want to indicate that something has been seen or noted to be present or occurring.
Example: "In the study, several phenomena are observed to exist under specific conditions."
Alternatives: "are noted to be present" or "are seen to occur".
PES was observed to exist in even the earliest samples collected in 1980 (unpublished observations), and has been identified in sequential cohorts of young adults transitioning into our clinic.
A strong correlation is observed to exist between the fracture strength, fracture morphology and defect chemistry in a tubular LSFCO membrane.
However, BDE-209 has been observed to exist in high levels (up to 177 ng/g lipid weight) in moose muscle samples, too [29].
Copolymer chains formed micelles at pH values higher than 5 whereas unimeric polymers were observed to exist below pH 5, owing to the repulsion between positively charged P4VP blocks.
A close relation of the distributor design to the hydrodynamics in monolith beds was observed to exist, evidenced by the larger pressure drop and liquid hold-up values for the monolith packings with an accompanying use of the packed bed distributor, as compared with the use of the nozzle distributor.
The trithiol form (I) is predominant in metal complexes [8, 9, 10, 11, 15], whereas the trithione form II) has been observed to exist in the mono-lithiated hexamethylphosphoramide complex and in the ammonium salts and solvent adducts of TCUA [7, 8, 12, 13, 14, 16, 17, 18, 22].
The SiN x interfacial phase is observed to exist as crystallized state, rather than amorphous state, such as the E zone between A and C crystals, F zone between A and B crystals, H zone between B and D crystals, and G zone between C and D crystals, which verifies the validity of above deduction.
The SiN x interfacial phase is observed to exist as crystallized state, rather than amorphous state, such as E zone between A and C crystals, F zone between A and B crystals, H zone between B and D crystals, and G zone between C and D crystals.
