prov:value
| - nitrogen atom, or the formula: ##STR2## wherein each of X1 is X2 is a hydrogen atom, a halogen atom or a nitro group, provided that when Y is a nitro group, X1 is a hydrogen atom, Y is a hydrogen atom, a halogen atom, a nitro group or a trifluoromethyl group, and Z is a hydrogen atom, a halogen atom or a trifluoromethyl group, characterized in that its average particle size is not larger than 1 ?
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