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#> 
PREFIX bibo: <http://purl.org/ontology/bibo/>

CONSTRUCT {
    ?vcard v:hasName _:name .
    _:name a v:Name .
    _:name v:givenName ?firstName .
} WHERE {
     ?s foaf:firstName ?firstName .
     ?s arg:ARG_2000028 ?vcard .
     FILTER NOT EXISTS {
         ?vcard v:hasName ?name
     }
}