Name a cation with strong interactions that starts with letter P
SELECT DISTINCT ?sbj ?sbj_label WHERE { ?sbj wdt:P31 wd:Q326277 . ?sbj wdt:P517 wd:Q11415 . ?sbj rdfs:label ?sbj_label . FILTER(STRSTARTS(lcase(?sbj_label), 'p')) . FILTER (lang(?sbj_label) = 'en') } LIMIT 25 
cation: Q326277 strong interaction: Q11415