static void Main(string[] args)
{
  var dt = new DataTable("phd_data");
  // имитация dt.Load
  dt.Columns.Add("name_ru", typeof (string));
  dt.Columns.Add("name_ua", typeof(string));
  foreach(var kvp in new Dictionary<string, string>
    {
      {"Австрия", "Австрія"},
      {"Англия", "Англія"},
      {"Россия", "Росія"}
    })
  {
    var dr = dt.NewRow();
    dr[0] = kvp.Key;
    dr[1] = kvp.Value;
    dt.Rows.Add(dr);
  }
  var xd = new XmlDocument();
  using(var xw = xd.CreateNavigator().AppendChild())
    dt.WriteXml(xw);
  var xslt = new XslCompiledTransform();
  using(var sr = new StringReader(Properties.Resources.Transform))
  using(var xr = XmlReader.Create(sr))
    xslt.Load(xr);
  using(var fs = new FileStream(@"D:\Trash\123.xml", FileMode.Create))
  using(var xw = XmlWriter.Create(fs, new XmlWriterSettings{Indent = true, IndentChars = "  "}))
    xslt.Transform(xd, xw);
  Console.WriteLine("done");
  Console.ReadKey();
}

<?xml version="1.0" encoding="utf-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:z="#RowsetSchema">
  <xsl:output method="xml" />
  <xsl:template match="/DocumentElement">
    <xml
      xmlns:s="uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882"
      xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882"
      xmlns:rs="urn:schemas-microsoft-com:rowset"
      xmlns:z="#RowsetSchema">
      <s:Schema id="RowsetSchema">
        <s:ElementType name="row" content="eltOnly" rs:CommandTimeout="30">
          <s:AttributeType name="name_ru" rs:number="1" rs:writeunknown="true">
            <s:datatype dt:type="string" dt:maxLength="128" rs:maybenull="false" />
          </s:AttributeType>
          <s:AttributeType name="name_ua" rs:number="1" rs:writeunknown="true">
            <s:datatype dt:type="string" dt:maxLength="128" rs:maybenull="false" />
          </s:AttributeType>
          <s:extends type="rs:rowbase" />
        </s:ElementType>
      </s:Schema>
      <rs:data>
        <xsl:apply-templates />
      </rs:data>
    </xml>
  </xsl:template>
  <xsl:template match="phd_data">
    <z:row>
      <xsl:for-each select="node()">
        <xsl:attribute name="{local-name()}">
          <xsl:value-of select="text()" />
        </xsl:attribute>
      </xsl:for-each>
    </z:row>
  </xsl:template>
</xsl:stylesheet>

<?xml version="1.0" encoding="utf-8"?>
<xml
  xmlns:s="uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882"
  xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882"
  xmlns:rs="urn:schemas-microsoft-com:rowset"
  xmlns:z="#RowsetSchema">
  <s:Schema id="RowsetSchema">
    <s:ElementType name="row" content="eltOnly" rs:CommandTimeout="30">
      <s:AttributeType name="name_ru" rs:number="1" rs:writeunknown="true">
        <s:datatype dt:type="string" dt:maxLength="128" rs:maybenull="false" />
      </s:AttributeType>
      <s:AttributeType name="name_ua" rs:number="1" rs:writeunknown="true">
        <s:datatype dt:type="string" dt:maxLength="128" rs:maybenull="false" />
      </s:AttributeType>
      <s:extends type="rs:rowbase" />
    </s:ElementType>
  </s:Schema>
  <rs:data>
    <z:row name_ru="Австрия" name_ua="Австрiя" />
    <z:row name_ru="Англия" name_ua="Англiя" />
    <z:row name_ru="Россия" name_ua="Росiя" />
  </rs:data>
</xml>