Umm...what's the question again? What do you mean AWOL, that the O.P. listed above hasn't been back with more, because they have. Or do you men no one's helped in the cases above, because there are a few responses. I'm not a chemical engineer or very proficient in organic synthesis, so I can't answer some of the more obscure questions, so some way out there questions may get ignored across the board, but only because we don't have someone skilled+patient enough, is that the problem? What, sjb:, do you really mean? Portugal, is that the user's name, or the domain?
*[EDIT]* Wait, do you mean the the posts by user Portugal: have disappeared? Did they change their username? That did happen once before.
*[EDIT again]* You mean no one answer's Portugal:'s questions? There seem to be a few responses to each. Is that it?