Significance
Recent studies on liquid water suggest that the two liquid waters exist in the supercooled temperature region and that their existence relates to the anomalous behavior of low-temperature liquid water such as the maximum density at 4 °C. However, the experimental investigation of two liquid waters is difficult because of the rapid crystallization. In this study, a reversible liquid–liquid transition in a trehalose aqueous solution by the change in pressure was observed directly. This result suggests strongly that two liquid waters exist in the aqueous solution. This study has implications for wide fields related to liquid water, such as solution chemistry, cryobiology, meteorology, and food engineering.
Abstract
Water forms two glassy waters, low-density and high-density amorphs, which undergo a reversible polyamorphic transition with the change in pressure. The two glassy waters transform into the different liquids, low-density liquid (LDL) and high-density liquid (HDL), at high temperatures. It is predicted that the two liquid waters also undergo a liquid–liquid transition (LLT). However, the reversible LLT, particularly the LDL-to-HDL transition, has not been observed directly due to rapid crystallization. Here, I prepared a glassy dilute trehalose aqueous solution (0.020 molar fraction) without segregation and measured the isothermal volume change at 0.01 to 1.00 GPa below 160 K. The polyamorphic transition and the glass-to-liquid transition for the high-density and low-density solutions were examined, and the liquid region where both LDL and HDL existed was determined. The results show that the reversible polyamorphic transition induced by the pressure change above 140 K is the LLT. That is, the transition from LDL to HDL is observed. Moreover, the pressure hysteresis of LLT suggests strongly that the LLT has a first-order nature. The direct observation of the reversible LLT in the trehalose aqueous solution has implications for understanding not only the liquid–liquid critical point hypothesis of pure water but also the relation between aqueous solution and water polyamorphism.
Data Availability
All study data are included in the article and/or SI Appendix.
- Copyright © 2022 the Author(s). Published by PNAS.
"direct" - Google News
January 25, 2022 at 03:18AM
https://ift.tt/3AwNIG5
Direct observation of reversible liquid–liquid transition in a trehalose aqueous solution - pnas.org
"direct" - Google News
https://ift.tt/2zVRL3T
https://ift.tt/2VUOqKG
Direct
Bagikan Berita Ini
0 Response to "Direct observation of reversible liquid–liquid transition in a trehalose aqueous solution - pnas.org"
Post a Comment