The invention provides thiazole derivatives of formula, or pharmaceutically acceptable salts thereof in which Ring A, R1, R2 and R3 are as defined in the specification; a processes for their preparation; pharmaceutical compositions containing them; and their use in therapy, for example in the treatment of disease mediated by a PI3K enzyme andor a mTOR kinase. The copolymers are usually used here in the form of aqueous dispersions. The high refractive index material layer is provided so as to fill at least the negative Fresnel lens shape of the structure body and thus has a surface including the region with the Fresnel lens shape at the interface with the structure body. In a rewashing treatment of textile dyed with reactive dyestuff, the textile is first rinsed with water to remove alkali and salt.