- date_default_timezone_set: documentation ( source)
<?php
date_default_timezone_set('Europe/Oslo');
$datetime = new DateTime();
echo $datetime->format('Y-m-d H:i:s.u')."\n";
$datetime = new DateTime('2016-08-07T11:59:12.345');
echo $datetime->format('Y-m-d H:i:s.u')."\n";