<?xml version="1.0" encoding="utf-8"?><!DOCTYPE Zthes SYSTEM "http://zthes.z3950.org/xml/zthes-05.dtd">  <Zthes><term><termId>31410817</termId><termName>nitrous oxide</termName><termType>PT</termType><termNote><![CDATA[ A colorless, sweet-smelling, sweet-tasting, non-flammable, slightly water-soluble gas, N2O. It is used chiefly as an anesthetic in dentistry and surgery, and in the manufacture of chemicals, such as aerosols. ]]></termNote><termCreatedDate>2026-03-30 20:50:27</termCreatedDate><relation><relationType>UF</relationType><termId>31410818</termId><termName>gas, laughing</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31410819</termId><termName>laughing gas</termName><termType>ND</termType></relation><relation><relationType>UF</relationType><termId>31410820</termId><termName>oxide, nitrous</termName><termType>ND</termType></relation><relation><relationType>BT</relationType><termId>31373690</termId><termName>nitrogen oxides</termName><termType>PT</termType></relation></term>  </Zthes>