<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31343583</termId><termName>rubidium</termName><termType>PT</termType><termNote><![CDATA[ Pure metallic element having symbol Rb and atomic number 37; soft, silvery white, and very reactive, rubidium is found as a trace constituent of various alkali minerals. It is used in photoelectric cells and as a catalyst.  ]]></termNote><termCreatedDate>2026-03-30 20:32:40</termCreatedDate><relation><relationType>UF</relationType><termId>31343584</termId><termName>Rb</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>