<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31319746</termId><termName>allotropes</termName><termType>PT</termType><termNote><![CDATA[ Structurally distinct forms in which a chemical element may occur. Some chemical elements may exist in two or more different forms, in the same physical state. Allotropes are different structural modifications of an element; the atoms of the element are bonded together in a different manner. ]]></termNote><termCreatedDate>2026-03-30 20:26:10</termCreatedDate><relation><relationType>UF</relationType><termId>31319747</termId><termName>allotrope</termName><termType>ND</termType></relation><relation><relationType>BT</relationType><termId>31305824</termId><termName>materials by chemical form</termName><termType>PT</termType></relation></term>  </Zthes>