Positronium decay in the ice-water system

Fabri, G.; Germagnoli, E.; Quercia, I. F.; Turrisi, E

doi:10.1007/bf02750745

Cited by 18 publications

(4 citation statements)

References 9 publications

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“…At this point (region III), the curve is at a maximum and begins a gradual decrease over all subsequent amounts of water absorption up to 60 wt % water. Extrapolation of the curve beyond 60 to 100 wt % water gives a value for pure liquid water consistent with the published values of τ 3 = 1.8 ns. , …”

Section: Resultssupporting

confidence: 86%

“…As the free water content increases in region III, more water is available to contribute to the overall I 3 value. The net I 3 value is biased increasingly toward that of pure water (28 ± 2%) , in much the same way as in the case of τ 3 in region III of Figure . Additionally, during this stage of water absorption, it is proposed that the prior crystalline regions with intermediate order have become less constrained and have adopted a completely random configuration.…”

Section: Resultssupporting

confidence: 57%

“…Extrapolation of the curve beyond 60 to 100 wt % water gives a value for pure liquid water consistent with the published values of τ 3 ) 1.8 ns. 34,35 The water enters initially as molecular water and hydrogen bonds to the hydroxyl groups. Calculation of the water content for one water molecule per hydroxyl group indicates that the first 29 wt % of water is in this strongly bound state.…”

mentioning

confidence: 99%

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Free Volume and the Mechanism of Plasticization in Water-Swollen Poly(vinyl alcohol)

et al. 1996

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Poly(vinyl alcohol), PVOH, films have been studied as a function of water content. The states of water present in the polymer (bound or free) have been characterized and are a function of water content. The effects of water content (and hence state) on the free volume, chain mobility, and glass transition (T g) behavior have been studied by positron annihilation lifetime spectroscopy, 13C solid state nuclear magnetic resonance, and dynamic mechanical analysis. The addition of approximately 30 wt % water results in a marked increase in free volume cavity size and polymer chain mobility and a corresponding decrease in T g. The water is in a molecular, nonfreezable state for water additions up to approximately 30 wt %, hence it is postulated that nonfreezing water is responsible for the majority of the plasticization in this system. The plasticization is attributed to the increasing free volume and lubrication provided as the water swells the polymer and disrupts polymer−polymer hydrogen bonding. A limited equivalence between the action of water on the polymer and the action of temperature (thermal energy) is proposed.

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Section: Resultssupporting

confidence: 86%

Section: Resultssupporting

confidence: 57%

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confidence: 99%

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Free Volume and the Mechanism of Plasticization in Water-Swollen Poly(vinyl alcohol)

et al. 1996

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“…2, 3, 4, and 5. The lifetime parameters for pure water are shown in each figure for comparison and are in good agreement with other reported values (Fabri et al, 1963;cf. Stewart and Roellig, 1967).…”

Section: Resultssupporting

confidence: 88%

Macromolecular conformation in solution. Study of carbonic anhydrase by the positron annihilation technique

Handel¹,

Graf²,

Glass³

1980

Biophysical Journal

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The structural features of carbonic anhydrase (carbonate hydro-lyase; EC 4.2.1.1) in aqueous solution were probed by the positron annihilation technique. The data obtained under varying conditions of temperature, pH, and enzyme concentration were interpreted in terms of the free volume model. The change of enzymic activity with temperature is accompanied by a change in free volume of the protein. Upon thermal denaturation an irreversible change in free volume of the molecule occurred. At low temperatures the protein-water interactions were investigated. These results are discussed in terms of current concepts of structure-function relationships in proteins. This study shows the sensitivity of the positron annihilation method toward the structure of proteins related to their overall conformation and to the nature of bound water.

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Mean life of positronium in liquid helium. Temperature and density effect

Manuzio

1966

Nuov Cim B

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Positronium decay in the ice-water system

Cited by 18 publications

References 9 publications

Free Volume and the Mechanism of Plasticization in Water-Swollen Poly(vinyl alcohol)

Free Volume and the Mechanism of Plasticization in Water-Swollen Poly(vinyl alcohol)

Macromolecular conformation in solution. Study of carbonic anhydrase by the positron annihilation technique

Mean life of positronium in liquid helium. Temperature and density effect

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