Ice-like Structure Research Articles

Positronium Formation in Muscle: An Investigation of the Structure of Cell Water

Positronium formation in muscle at +4 degrees C and -4 degrees C was examined by the measurement of the angular correlation of positron annihilation radiation. Since the positronium formation rate in ice is considerably higher than it is in water, there should be a comparable increase in the positronium formation rate in muscle tissue if recent speculation that cellular water is ordered in a semicrystalline icelike state is correct. Comparison of the angular correlation from muscle at +4 degrees C with that from water at +4 degrees C shows no enhancement of the positronium formation rate. Frozen muscle at -4 degrees C shows an enhancement of the positronium formation rate of approximately half that found in ice at -4 degrees C, indicating that most cellular water undergoes a normal water-ice transition when frozen. It is concluded therefore that cell water in muscle is not ordered in a hexagonal icelike structure. While the results are consistent with the hypothesis that cell water is in the liquid state, the hypothesis that cell water is ordered in an undetermined close packed structure which transforms to the hexagonal ice structure at or near 0 degrees C cannot be ruled out.

Origin of Ultrasonic Absorption in Heavy Water

Hall's theory of structural relaxation is applied to explain the excess ultrasonic absorption in ${\mathrm{D}}_{2}$O. Two states, one characterized by higher volume and lower energy (icelike structure) and the other characterized by lower volume and higher energy (close-packed structure) are assumed to be available to each molecule of ${\mathrm{D}}_{2}$O. The occurrence of a density maximum ${\ensuremath{\rho}}_{max}$ at 11.2\ifmmode^\circ\else\textdegree\fi{}C and a static compressibility minimum ${\ensuremath{\beta}}_{0 min}$ at about 75\ifmmode^\circ\else\textdegree\fi{}C favors a two-state model for ${\mathrm{D}}_{2}$O. The absorption coefficient is calculated with three trial values of ${\ensuremath{\beta}}_{\ensuremath{\infty}}$ (16\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}12}$, 17\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}12}$, and 18\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}12}$ ${\mathrm{cm}}^{2}$/dyn). It is found that with ${\ensuremath{\beta}}_{\ensuremath{\infty}}=17\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}$ ${\mathrm{cm}}^{2}$/dyn, Hall's theory agrees very well with the experimental results.

Sorbed water on polymers near 0 °C

Sorption of water has been measured for polyacrylonitrile, polymethylmethacrylate, and atactic and isotactic polystyrene over a range of temperatures from negative to positive degrees centigrade and for polyvinylpyrrolidone at −2 °C, +7 °C and +10 °C. The isosteric heats and differential molar entropies as function of coverage show in the cases of polyacrylonitrile and polymethylmethacrylate that water below monolayer coverage is less strongly bound and of less order then condensed water. At about one monolayer coverage, the sorption goes over to condensation of water. Parameters derived from the BET equation are in agreement with the conclusions derived from isosteric heats and entropies of adsorption. Atactic and isotactic polystyrene do not sorb water at all up to a relative pressure of 0.85 but adsorb some water at higher relative pressures. Polyvinylpyrrolidone is a special case, as it is water soluble. The sorption isotherms have a zero temperature coefficient. They are similar to the “isotherm” previously obtained for “bound” water in freezing PVP solutions. The conclusion is reached that water sorbed on or “bound” to PVP has an ice-like structure.

The Structure Theory of Water. I. Two State Theory

Abstract A statistical thermodynamic theory was successfully applied to liquid water, based on the two state model which consists of an ice-like structure (class I) and unbonded monomers (class II). The resulting partition function was formulated and calculated using the two quantities, the energy difference between class I and class II, ε, and the free volume per molecule, vf, as the adjustable parameters which were varied within the physically-reasonable range. The magnitudes of ε and vf were estimated to be 3 kcal/mol and 4.0×10−25 cm3 respectively to give the best fit of calculated values to the experimental data. From the partition function obtained, the Helmholtz energy, the internal energy, the entropy, and the specific heat were calculated. The agreement between the calculated values and the experimental data was found to be satisfactory. From the obtained result it may be concluded that the simple two state model is adequate to explain the thermodynamical data for liquid water.

Position of water molecules in cavities of the ice-like structure of liquid water, and the degree of filling the cavities

Position of water molecules in cavities of the ice-like structure of liquid water, and the degree of filling the cavities

On the hydrogen bond in an ice-like structure

The interactions of a water molecule with its first and second neighbors in an ice-like structure are studied, and several definitions and methods of calculation are compared. An attempt is made to calculate the cooperative effect which is found to be smaller than the thermal energy kT at 0°C.

Hall Effect in Dielectric Media: Microwave X-Band Faraday Rotation of Water Adsorbed on Hemoglobin

The structure of bound water molecules in crystalline, bovine hemoglobin powder is investigated with a microwave technique of Faraday rotation at a frequency of 9.36 Gc/sec. An expression for the Faraday rotation due to displacement-current Hall field is derived in terms of dipole concentrations of free water molecules and is applied to measure the changes from free water to bound water molecules on hemoglobin with variable amounts of adsorbed water. In agreement with the theory, the experimental result shows a linear relationship between the angle of rotation and the concentration of free water dipoles up to the hydration level of 0.13 g of water per gram of dry hemoglobin. Above this hydration level, the formation of icelike structures on the surface of hemoglobin is discussed based on our experimental results.

Conductance and transport numbers of mixtures of hydrochloric and maleic acids at 25°C

Transport number experiments on mixtures of hydrochloric and maleic acids showed that the mobility of the maleate ion increases, whereas that of the H+ and Cl− ions decreases, with increase in maleic acid concentration up to 0·12 M. Conductance measurements indicated an initial rise in the specific conductance of HCl with increase in maleic acid concentration. These results are interpreted on the basis of an increase in the ice-like structure of liquid water through the presence of maleic acid.

Thermodynamics of cation exchange. Part 4.—Uni-, bi- and tervalent ions on Dowex 50

The heats, volumes and entropies of exchange of potassium by a series of cations of various valencies on Dowex 50 crosslinked with 4, 8 and 16% divinyl benzene have been determined. The exchange of potassium by bi- and tervalent ions is endothermic. The heats are 1.5-2.5 kcal/equiv. Much of this heat can be accounted for by the change in electrostatic energy on transferring ions between the solution and the resin. Heat effects arising from changes in ionic hydration may also be important. The net volumes of exchange may be of either sign. They reflect the changes in hydration of the ions. Ions of small [graphic ommitted] electrostrict less water in the resin than in the solution. This causes an expansion when these ions enter the resin. Ions of large [graphic ommitted] create less icelike structure in the resin than in solution. This causes a contraction when the ions enter the resin. The preference shown by resins for ions of high valence results from an increase in entropy on exchange. When calculated with respect to an appropriate set of standard states the experimental entropies of exchange are almost entirely a consequence of changes in the configurational entropy of the ions. Although the changes in ionic hydration produce a relatively small net contribution to the entropy of exchange, this is influential in deciding the relative selectivities towards ions of equal valence and also in determining the effect of crosslinking on selectivity.

Two-State Theory of the Structure of Water

A new model of the structure of water is proposed. This model is based on the existence in water of puckered hexagonal rings similar to those in ice. In water, these rings are assumed to coexist in two structures: an open-packed icelike structure optimum for forming hydrogen bonds between rings, and a close-packed structure in which the molecules occupy a nearly complete body-centered cubic structure. Mole fractions and volumes consistant with both the specific volume and the observed radial distribution curve of water are obtained. The structure of water is estimated to be approximately 60% icelike at 0°C and 30% icelike at 100°C. The corresponding fractional amount of hydrogen bonding at 0°C is found to be 82% in good agreement with recent estimates from Raman spectral observations. A simple two-state expression for the expansivity is shown to agree with the observed thermal expansion of water over the temperature range 0° to 100°C. The lattice component (and therefore, at 4°C, the magnitude of the relaxational or configurational component) is 1.634×10−3/C°. Using these values, estimates of various other two-state thermodynamic parameters are obtained. Both the specific heat and compressibility of water are found to be approximately 50% structural over the temperature range.

Water Structure around Silver Iodide Sol Particles

IN order to explain lower values of differential capacity at the negative silver iodide/solution interface than at the mercury/solution interface, Lyklema1 proposed that the Stern layer in the former may be of icelike (tetrahedral) structure, and pointed out that this would also explain the greater specificity of cations in the silver iodide case. More recently Levine and Bell2 have commented that such structure would tend to remove the distinction between inner and outer Helmholtz planes so that the fluctuation potential would become small, this making the maximum in the outer Helmholtz plane potential much less marked. This effect would then explain the relative constancy of the flocculation concentration for silver iodide sols at high (negative) potentials3,4 compared with those of silver bromide and silver chloride sols, which have been reported5 to decrease at high negative potentials. The hypothesis is supported by the well-known epitaxis of ice on silver iodide which is more effective near the zero point of charge6.

Dielectric properties of water of adsorption on protein crystals

AbstractThe dielectric properties of dry and wet protein crystals were studied in a wide frequency range. The dry protein crystals did not have appreciable dielectric constant until the water content was about 15–20%. However, further increase of water of hydration (and/or adsorption) suddenly increased the dielectric constant of the crystals, and it reached a very large value which cannot be explained merely by the orientation of water of hydration (and/or adsorption). However the increase of dielectric constant leveled off rapidly, and further addition of water did not have significant effect. Thus the dielectric constant–water content plot followed a curve which was similar to the Langmuir adsorption isotherm. This fact strongly indicates that the dielectric constant of hydrated crystals arises, for the most part, from the polarizability of the first hydration layer of the protein molecules, which supposedly have an icelike structure.

Self-diffusion of water in tobacco mosaic virus solutions

Self-diffusion coefficients for water in solutions of tobacco mosaic virus have been measured near the critical concentration of the solutions. The diffusion coefficients of the water in the solutions is very close to the diffusion coefficient of water in pure water. It is concluded from this data that no more than 3% of the water in a 4% tobacco mosaic virus solution is in a bound ice-like state. This statement is in disagreement with Jardetsky and Jardetsky who conclude from nuclear magnetic resonance measurements that as much as 20% of the water in a 1.9% tobacco mosaic virus solution exists in an ice-like structure.

A tentative interpretation of the results of recent X-ray and infra-red studies of liquid water and H 2 O + D 2 O mixtures

An idealized model is proposed for the arrangement of the molecules in liquid water which involves essentially a sixfold co-ordination of water molecules with four short OH...O hydrogen bonds of ~2.9 Å length and two long O...O contacts of ~3.6 Å length. An ice-like structure may contribute to a small extent also. This octahedral model has been based on evidence obtained from X-ray and infra-red absorption measurements. The model has been found to be in agreement with the density of water and the melting entropy of ice. The reliability of the radial distribution curves W(r) of liquid water obtained from recent X-ray diffraction measurements is discussed. Infra-red absorption measurements have been made of liquid HDO in excess D 2 O and H 2 O, respectively. The respective O—H and O—D stretching vibration frequencies of liquid HDO have been determined. The position (at 3400 cm -1 ) and shape of the relatively sharp single O—H stretching absorption band of liquid HDO is closely comparable to the corresponding band in liquid interbonding alcohols. The results of the infra-red studies indicate an OH...O distance of 2.86 Å in liquid water at room temperature.