All 45 stores in the Borders U.K. bookselling chain are closing today because administrators failed in their attempts to find buyers for any or all of the stores.  This marks the final chapter in the saga of the Borders book chain in the United Kingdom.  Restructuring specialists at Hilco, which invested 6 million pounds in a management buyout of the British Borders chain in July, have been managing the shut down of the stores, which as recently as November employed some 1,100 workers at various locations in the U.K.