PREFIX arg: <http://purl.obolibrary.org/obo/> 
PREFIX foaf: <http://xmlns.com/foaf/0.1/> 
PREFIX v:   <http://www.w3.org/2006/vcard/ns#> 
PREFIX vivo: <http://vivoweb.org/ontology/core#> 

CONSTRUCT {
    ?vcard v:hasEmail _:email .
    _:email a v:Email .
    _:email v:email ?email .
} WHERE {
    ?s vivo:email ?email .
    ?s arg:ARG_2000028 ?vcard .
    FILTER NOT EXISTS {
        ?vcard v:hasEmail ?emailnode
    }
}