n>&#160;                                              <span class="stringliteral">&#39;GD&#39;</span>,  <span class="comment"># gadolinium atom</span></div><div class="line"><a name="l00052"></a><span class="lineno">   52</span>&#160;                                              <span class="stringliteral">&#39;PER&#39;</span>,  <span class="comment"># peroxide ion</span></div><div class="line"><a name="l00053"></a><span class="lineno">   53</span>&#160;                                              <span cl