<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31343594</termId><termName>ytterbium</termName><termType>PT</termType><termNote><![CDATA[ Rare metallic element, the penultimate in the lanthanide series, having the symbol Yb and atomic number 70. Ytterbium is a soft, lustrous silver-white metal. Some of its isotopes generate gamma rays when irradiated and are used as a radiation source-substitute for portable X-ray machines. ]]></termNote><termCreatedDate>2026-03-30 20:32:40</termCreatedDate><relation><relationType>UF</relationType><termId>31343595</termId><termName>Yb</termName><termType>ND</termType></relation><relation><relationType>BT</relationType><termId>31375243</termId><termName>nonferrous metal</termName><termType>PT</termType></relation><relation><relationType>BT</relationType><termId>31319740</termId><termName>elements</termName><termType>PT</termType></relation></term>  </Zthes>