//ultimos eventos
    var now = moment();
    var endDate = now.format("x"); //data atual em unix
    var startDate = now.subtract(10,'hours').format("x");

    console.log(startDate);
    console.log(endDate);

    var uv = this.af.list('/pedidos/', ref => ref.orderByChild('now').startAt(startDate).endAt(endDate));
    uv.snapshotChanges().pipe(

      map(actions =>
        actions.map(a => ({key:a.key, ...a.payload.val()}))

        )
    )

    .subscribe(items =>{

      this.ultimosEventos = items;
      console.log(items);

    });