title: Heterogeneities in confined water and protein hydration water.
abstract: We report recent efforts to understand a broad range of experiments on confined water and protein hydration water, many initiated by a collaboration between workers at the University of Messina and MIT-the editors of this special issue. Preliminary calculations are not inconsistent with one tentative interpretation of these experiments as resulting from the system passing from the high-temperature high-pressure 'HDL' side of the Widom line (where the liquid might display non-Arrhenius behavior) to the low-temperature low-pressure 'LDL' side of the Widom line (where the liquid might display Arrhenius behavior). The Widom line-defined to be the line in the pressure-temperature plane where the correlation length has its maximum-arises if there is a critical point. Hence, interpreting the Messina-MIT experiments in terms of a Widom line is of potential relevance to testing, experimentally, the hypothesis that water displays a liquid-liquid critical point.
authors.affiliation: Center for Polymer Studies and Department of Physics, Boston University, Boston, MA 02215, USA.
authors.forename: H E
authors.initials: HE
authors.lastname: Stanley
authors.forename: P
authors.initials: P
authors.lastname: Kumar
authors.forename: S
authors.initials: S
authors.lastname: Han
authors.forename: M G
authors.initials: MG
authors.lastname: Mazza
authors.forename: K
authors.initials: K
authors.lastname: Stokely
authors.forename: S V
authors.initials: SV
authors.lastname: Buldyrev
authors.forename: G
authors.initials: G
authors.lastname: Franzese
authors.forename: F
authors.initials: F
authors.lastname: Mallamace
authors.forename: L
authors.initials: L
authors.lastname: Xu