<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31320471</termId><termName>silica</termName><termType>PT</termType><termNote><![CDATA[ The dioxide form of silicon, SiO2, occurring in quartz sand, flint, and agate. It is used chiefly in its prepared white powder form in the manufacture of glass, ceramics, and abrasives. ]]></termNote><termCreatedDate>2026-03-30 20:26:22</termCreatedDate><relation><relationType>UF</relationType><termId>31320472</termId><termName>dioxide, silicon</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31320473</termId><termName>silicon dioxide</termName><termType>ND</termType></relation><relation><relationType>BT</relationType><termId>31306143</termId><termName>inorganic material</termName><termType>PT</termType></relation><relation><relationType>NT</relationType><termId>31344762</termId><termName>organically modified silica</termName><termType>PT</termType></relation></term>  </Zthes>