string xmlDateFormat(DateTime dt)
{
Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");
//Sat, 14 Mar 2015 17:10:42 -0400
var f = string.Format(@"{0:ddd, dd MMM yyyy HH:mm:ss }{1}", dt, string.Format("{0:zzz}", dt).Replace(":", ""));
return f;
}