tle="" class="an ">&ensp;</span>p <span  title="" class="an ">&ensp;</span>S <span  title="" class="an ">&ensp;</span>longer <span  title="" class="an ">&ensp;</span>mean <span  title="" class="an ">&ensp;</span>open <span  title="" class="an ">&ensp;</span>times <span  title="" class="an ">&ensp;</span>that <span  title="" class="an ">&ensp;</span>showed <span  title="" class="an ">&ensp;</span>a <span  title="" class="an ">&ensp;</span>voltage <span  title="" class="an ">&ensp;</span>dependent <span  titl