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A 5-day training camp was designed including a hydration strategy to help female field hockey players improve performance during competition in Malaysia. Cycling exercise, recommended snack choices, and monitoring urine color contributed to improved hydration and game play.

A new study investigates the hydration changes that accompany the DNA binding of the intercalators propidium, ethidium, daunomycin, proflavine and 7-aminoactinomycin D.

Research into the differential hydration of alpha, omega-aminocarboxylic acids in H2O and D2O is presented.

Issues concerning the hydration of the yttrium(III) ion in aqueous solution are presented. The ion is found to be hydrated by eight water molecules in aqueous solution.

Issues concerning the testing of both a model and the method of the hydration of sodium dodecyl sulfate micelles are reported.

A study of the Cu2+ hydration shell structure uses a combined ab initio quantum mechanical/molecular mechanic Monte Carlo simulation.

Research is presented using a computational approach within a Langevin dipoles solution model to determine the entropies of transfer of molecules from the gas phase to aqueous solution.

The hydration numbers of lanthanoid(III) chelates with 2-thenoyltrifluoroacetone prepared by extracting into chloroform have been determined by analyzing the relation between lanthanoid(III) concentration and water content, The water contents were measured by coulometric Karl Fischer titration, and the concentration of lanthanoid(III) extracted was determined by ICP/AES. The hydration number of europium(III) chelate was also checked by measuring the luminescence lifetime. The hydration number is about 3 from lanthanum to holmium and then decreases to about 2.4. The change reflects the variation in the lanthanoid(III) ionic size. The hydration number of Eu(TTA)(sub 3) obtained by the Karl Fischer titration agrees with that from measurement of the luminescence lifetime, within experimental accuracy.

Research is presented describing the investigation for protonated hydrophobe-containing water clusters in charge-enhanced hydrophobic hydration.

Research has been conducted on the ligand field stabilization energy. The application of the energy to the hexaaqua 3+ complex hydration enthalpies has been investigated.

The stability of synthetic cation-exchanged zeolites having the chabazite framework (CHA) and their cation-water interaction were studied using high-temperature reaction calorimetry. Four cations (K, Na, Li, and Ca) were exchanged into CHA. The enthalpies of formation were determined for all samples, and the partial molar enthalpy of hydration was measured by varying the water content of one Ca-CHA. The enthalpy of formation depends strongly on the exchanged cation, becoming more exothermic in the order Ca, Li, Na, K. The integral hydration enthalpy does not depend strongly on the nature of the cation, but becomes slightly less exothermic with increasing aluminum content. For the one Ca-CHA studied in detail, the average enthalpy of hydration is -34.6 +/- 1.2 kJ/mol relative to liquid water. A quadratic fit to the transposed temperature drop data gives (delta) h(sub H(sub 2)O) = -52.97 (+/- 4.74) + 2.94 (+/- 0.68) n (kJ/mol), where (delta) h(sub H(sub 2)O is the partial molar enthalpy of hydration and n is the number of water molecules per 24 oxygen formula.

Ultra-thin water films, their instability, and the mechanism of droplet formation on hydrophilic surfaces are discussed with presentation of a new theory that uses new knowledge of intermolecular forces. Hydration, van der Waals, and electrostatic and elastic strain interactions are used. The theory shows contributions to the disjoining pressure are dominated by hydration forces for films thinner than 3 nm and predicts that beyond a certain value of subcooling, interdroplet spacing is choked and cannot decrease more. Internuclei spacing is shown to be larger than the critical wavelength. Intermolecular

Standard enthalpies of isomerization and hydrogenation and formation of norbornadiene, quadricyclane, nortricyclane, norbornene and norbornane have been calculated. Comparison between combustion and hydrogenation thermochemical results is discussed.

Two model substrates have been used for analysis of stereochemical and structural aspects for the carbon dioxide fixation and hydration of D-ribulose 1,5-bisphosphate. Transition structures invariances have been discussed.

Spectroscopic, calorimetric, density and ultrasonic techniques have been used for determination of hydration effects on the formation of DNA, RNA and DNA/RNA oligomer duplexes. The uptake of hydrophobic water and release of electrostricted water have been suggested.

Author's Abstract, COPYRIGHT 1999, Mineralogical Society of America Ab initio quantum mechanical calculations were performed on Al(OH)(sub 3), A1(OH)(sub 4), NaAl(OH)(sub 4) and related species with varying numbers of explicit water molecules to elucidate the structural, spectral and energetic properties of the possible species. We find that Al(OH)(sub 3) reacts with H(sub 2)O in the gas-phase with an exoergicity of 24.1 kcal/mol to produce Al(OH)(sub 3)H(sub 2)O, which has shorter a1-OH distances, larger Al-OH stretching frequencies, and a 15 ppm larger Al NMR shilding than does A1(OH)(sub 4). When the first hydration spheres of these species are included the Al NMR shielding becomes very similar, but the O and H NMR parameters and the IR and Raman spectra still show significant differences. The hydration energy of A1(OH)(sub 3)H(sub 2)O is determined from a 'supermolecule' calculaton on Al(OH)(sub 3)H(sub 2)O...6H(sub 2)O, where as that for Al(OH)(sub 4) is obtained using the supermolecule calculation on Al(OH)(sub 4)...6H(sub 2)O plus an evaluation of the electrostatic Born Hydration energy of the supermolecule. The calculated energy change for the acid dissociaton reaction, Al(OH)(sub 3)H(sub 2)O...6H(sub 2)O - Al(OH)(sub 4)...6H(sub 2)O + H(super +), is +297.9 kcal/mol in the gas phase but only +2.3 kcal/mol in aqueous solution, due to the strong hydration of H(super +) and Al(OH)(sub 4)...6H(sub 2)O. Using quantum mechanicallycalculated entropies for the unhydrated species, Al(OH)(sub 3)H(sub 2)O and Al(OH)(sub 4), pus the experimental hydrationentropyof H(super +), the -T delta S term for this reaction is calculated as about +11.8 kcal/mol. Adding in calculated zero-point energies and room temperature enthalpy corrections gives a free energy change of +0.5 kcal/mol. Thus pKa for the acid dissociation of Al(OH)(sub 3)H(sub 2)O is near zero at room T, and Al(OH)(sub 4) will be dominant except under very acidic conditons. Properties are also calculated for the bare close-contact ion pair NaAl(OH)(sub 4) and for hydrated forms of both a close-contact and a solvent-separated ion pair, NaAl(OH)(sub 4)...10H(sub 2)O and NaAl(OH)(sub 4)...11H(sub 2)O. In accord with previous calculations on silicate anions and ion pairs, formation of an unhydrated close-contact ion pair increases the shielding of the Al in Al(OH)(sub 4), while reducing the Al-O symmetric stretching frequency. The calculated energy change at 298 K in aqueous solution for the ion pair formation reaction. Na...6H(sub 2)O(super +) = Al(OH(sub 4)...6H(sub 2)O > NaAl(OH(sub4)...11H(sub 2)O + H(sub 2)O. is + 17.6 kcal/mol, close to the value determined experimentally. After addition of calculated zero-point energies, enthalpycorrections, and calculated entropychanges we obtain a delta G value of +1.7 kcal/mol for this reaction, giving a log K around -1, consistent with significant ion pair formation. The NaAl(OH)(sub 4)...11H(sub 2)O species is a solvent-separated ion pair with full hydration of both its Na(super +) and Al(OH)(sub 4). Its calculated Al NMR shielding and Al-O symmetric stretching frequencies are very similar to those for Al(OH)(sub 4)...6 H(sub 2)O, whereas its Na NMR shielding is about 5 ppm smaller than that of Na(OH(sub 2)(sub +6), although its Na electric field gratient (and consequently its line-width) are larger. Thus it appears that Na NMR may be the best technique for characterizing this ion pair.

Research has been conducted on the archaea plant-type (beta-class) carbonic anhydrase. Results indicate that beta-class carbonic anhydrases extend into thermophilic prokaryotes.

Neutron scattering technique has been used to study structural and dynamical properties of hydration water and its influence on the behavior of halobacteria purple membranes. Results demonstrate the effect of hydration process on the membrane properties.

The results of hydration structure studies of 15C5 and 18C6 are reported.

Research was conducted to examine the impact of anions on the stability of various functional conformations of hemoglobin (Hb) via the determination of the dependence of O2 affinity on water activity. Using equations of chemical linkage or a formalism based on the Gibbs-Duhen equation, it was determined that approximately 70 water molecules bind to Hb with oxygenation. Results clearly suggest that the hydration change probed by osmotic stress is intrinsically correlated with the global conformational changes related to allosteric binding in solution

The pressure dependence of the rotational mobility of benzene was investigated in dilute solutions of water and methanol at various temperatures and pressures. The hydration shell was found to be vulnerable to pressure at higher temperatures. At lower temperatures, a strong hydration shell was observed, in which a benzene molecule can reorient with little pressure effect.

Research was conducted to examine the rates and products of the acid-catalyzed hydrolysis of arylcyclohexene oxides. It was observed that the electronic nature of the para-substituent within the series does not have a large or systematic effect on the cis/trans hydration ratio. It is, therefore, proposed that epoxide ring opening with hydronium ion results in a discrete carbocation intermediate that undergoes partitioning reactions with solvent to generate cis- and trans-diol products.

The experimentally obtained azide/solvent selectivity data (log S) for 22 nitrenium ions were contrasted with the relative hydration energies computed for these same ions at the RHF/6-31G*//3-21G level of theory. Except for the most reactive of these ions, there was a good linear correlation of log S with the relative hydration energies that is broken only by the most selective ion for which the computation was performed. Results add to the increasing number of experimental data indicating that the dominant canonical form of most N-arylnitrenium ions is a iminocyclohdexadienyl cation-like structure.

Research was conducted to examine the potassium and sodium binding to the outer mouth of the K+ channel. The molecular dynamics simulations of the K+ channel from Streptomyces lividans were carried out in a membrane-mimetic environment with Na+ and K+ in various initial locations. Results indicate that the hydration state of the metal ions depends substantially on the conformational flexibility of the channel. The different hydration state of the two ions may be a determinant factor in the ion selectivity of the channel.

The interaction of sodium and cesium chloride salts with calcium silicate hydrates (C-S-H) was investigated using solid-state nuclear magnetic resonance spectroscopy. Results showed that Cs+ and Na+ have a liking for the C-S-H surface, but each behave differently due to their different hydration energy. Moreover, the cations may be located in a diffuse ion swarm in hydrated C-S-H, but would form outer-sphere complexes in dry C-S-H.

A study has been conducted to determine the main interaction configurations that embedded H2O molecules adopt in resins. Two amine-cured epoxy resins were used to facilitate the monitoring of hydration processes using infrared spectrometry. H2O molecules are not easily observable in polymers since it is extremely difficult to localize small and versatile molecules as these can rapidly change their interactions with neighboring molecules. Irradiation has been found to have a distinct effect on hydration kinetics.

Neutral solutes were used to study the effects of hydration on the activating conformational change of the receptor rhodopsin and on the acyl chain packing of the rod outer segment disk membrane. The solutes glycerol, sucrose and stachyose were found to increase the equilibrium concentration of metarhodopsin II, the conformation of photoactivated rhodopsin. Results also suggested that water molecule binding and release are essential in regulating functional conformational changes for integral membrane and soluble globular proteins.

A study was conducted to analyze an alanine dipeptide molecule in aqueous solution using molecular dynamics computer simulations. The structural and dynamical characteristics of the hydration water molecules were computed separately for solvent molecules surrounding different atoms or atomic groups. Results indicated differences between the properties of water around the polar and nonpolar atomic groups.

Fourier transform infrared spectroscopy is used to study the hydration of tetrabutylammonium cation, Bu4N+, in aqueous solutions of Bu4NBr, Bu4NCl and BU4NF salts. It is shown that the energetic state of water H-bonds and water O...O distances are similar to the one for bulk water. However, the population of H-bonds around the cation is larger. Hydrophobic hydration is also considered an entropy effect.

Expanding upon our previous studies of the properties of Au complexes, we present calculations for several [Hg.sup.2+] species in aqueous solution and for molecular models for cinnabar. Hydration effects are treated with a combination of 'supermolecule' calculations containing several explicit water molecules and polarizable continuum calculations. We focus upon the following problems: (1) calculation of the stabilities of Hg[L.sub.2], L = [F.sup.-], [Cl.sup.-], O[H.sup.-], S[H.sup.-], and C[N.sup.-] and [Mathematical Expression Omitted]; (2) development of a molecular model for cinnabar of the form [Hg.sub.3][S.sub.2][(SH).sub.2]; and (3) dissolution or adsorption reactions using this cinnabar model. The absolute and relative formation enthalpies of the Hg[L.sub.2] species can be satisfactorily reproduced at the Hartree-Fock plus Moller-Plesset second order correlation correction level using relativistic effective core potential basis sets if the hydration of neutral Hg[L.sub.2] is explicitly taken into account. Evaluating the energetics for the series of complexes [Mathematical Expression Omitted] is more difficult, because great accuracy is needed in the large hydration energies and some of the species are highly nonspherical. The [Hg.sub.3][S.sub.2][(SH).sub.2] species shows an equilibrium structure very much like that in cinnabar. The relative energetics for dissolution of cinnabar by [H.sub.2]O, [H.sub.2]S, S[H.sup.-], and S[H.sup.-] + elemental S are correctly reproduced using this model molecule. Calculations on [Hg.sub.3][S.sub.2]ClI provide a model for understanding the adsorption of [I.sup.-] ions on cinnabar surfaces in the presence of [Cl.sup.-].

Density functional theory was used to study hydration of the keto group and hydrolysis of alpha-oxo carboxylic acid derivatives, with both uncatalyzed and water-assisted processes taken into account. The self-consistent isodensity surface polarized continuum model was used to approximate solvent effects, while a concerted and a stepwise mechanism was calculated for hydrolysis reactions. In uncatalyzed processes, both concerted and stepwise mechanisms were calculated to have comparable activation energies and free enthalpies, while in catalyzed reactions, the stepwise mechanism is projected to be appreciably more favorable.

Research was conducted to examine the structure of octakis(2,3,6-tri-O-methyl)-gamma-cyclodextrin (TRIMEG) crystalized from saturated aqueous solution at 18 degrees C. Ab initio real/reciprocal space recycling technique was used to determine the structures of the four TRIMEG molecules having a similar elliptical shape with pseudo-2-fold rotational symmetry. Results suggest that other methylated CDs are hydrated in a similar way at low temperature which may explain their high solubility.

The mechanism of hydration of the 18-crown-6 molecule has been investigated in aqueous solution using the near-infrared spectral technique. In addition, the hydration numbers of the molecule at various concentrations were examined. Results show near-infrared difference spectra of 18-crown-6 molecule in the 1350-1650 nm region. Four complexed water molecules were found to be hydrogen-bonded to the crown ether ring with D(sub 3d) conformation.

The hydration of the actinyl cations, uranyl UO2(super 2+) and plutonyl PuO2(super 2+), has been investigated. Kohn-Sham Density Function Theory calculations using the MAGIC quantuam chemistry code have been performed on the separate uranyl and plutonyl species, and on the complexes AcO2(super 2+).nH2O (AC = U, Pu; N = 4, 5, 6). The results showed that the solvent plays a critical role in the hydration process wherein the solvent molecules were found to behave like actual binding equatorial ligands.

Ab initio methods are used to examine the potential energy surface for the interaction of uracil with one water molecule. By applying Moller-Plesset perturbation theory and the interaction-optimized DZPi basis set, the structures of four cyclic minima are determined together with two transition-state structures. Experimental results can be used in the improvement of existing model potentials for uracil-water interaction, with the aim of simulating clusters of uracil surrounded by water molecules.

Capillary viscosimetry was used in studying dilute aqueous nonionic surfactant vesicle dispersions formed from hexadecyl diglycerol ether (C16G2) or sorbitan monostearate (Span 60). Polyhedral or spherical structures are formed when the ratio of C16G2, cholesterol or Solulan C24 are varied. It has been observed that there is a little change in the relative viscosity of spherical/tubular niosome dispersions as the temperature increases. However, there is a significant reduction in the relative viscosity of polyhedral dispersions. This indicates that the shape of the dispersions become spherical.

Rat wild-type mitochondrial 2-enoyl-CoA hydratase-1 is capable of catalyzing isomerization with the activity ratio of isomerization to hydration of 1 is to 5000. The kcat values of isomerization in the active mutants Glu164Ala and Glu144Ala diminished 1000-fold and 10-fold, respectively. The result, which favors the hydratase reaction over the isomerase reaction has been tackled by investigating the differing enzymological attributes of the Gln162Met, Gln162Leu and Gln162Ala mutants.

Several strategies can be used to determine the amount of fluids needed to replace moisture lost during hard work or exercise. Research and tests should focus on the amount of water lost through sweating, and resulting formulas should account for high temperatures in addition to physical activity. These can be used to prevent dehydration and heat-related illnesses.

A study was conducted to characterize the hydration properties of the component chemical groups of amino acids and oligoglycines in D2O (heavy water) and to compare the data to those for the same groups in H2O that have been reported in previously published studies. The experiment reports the partial molar volumes and adiabatic compressibilities for two homologous series in D2O at 25 degrees centigrade, amino acids with aliphatic side chains and oligoglycines.

The size-selected cluster ions, I-.Wn, were isolated in the gas phase and used to sequentially assemble the solvation sphere around the iodide ion. Water molecules were observed to sequentially lock into position to form supramolecular complexes at the initial stages of hydration. The vibrational dissociation spectra were obtained for supramolecular complexes quenched close to the minimum energy configurations by complexation with argon. The I-.W3 cluster was observed to form a pyramid with the ion on top a symmetrical water trimer.

We have combined neutron solution scattering experiments with molecular dynamics simulation to isolate an excess experimental signal that is caused solely by N-acetyl-leucine-amide (NALA) correlations in aqueous solution. This excess signal contains information about how NALA molecule centers are correlated in water, and we show how these solute-solute correlations might be determined at dilute concentrations in the small angle region. We have tested qualitatively different pair distribution functions for NALA molecule centers - gas, cluster, and aqueous forms of[g.sub.c](r) - and have found that the excess experimental signal is adequate enough to rule out gas and cluster pair distribution functions. The aqueous form of [g.sub.c](r) that exhibits a solvent-separated minimum, and possibly longer-ranged correlations as well, is not only physically sound but reproduces the experimental data reasonably well. This work demonstrates that important information in the small angle region can be mined to resolve solute-solute correlations, their lengthscales, and thermodynamic consequences even at dilute concentrations. The hydration forces that operate on the microscopic scale of individual amino acid side chains, implied by the small angle scattering data, could have significant effects on the early stages of protein folding, on ligand binding, and on other intermolecular interactions.

Research was conducted to examine sodium diffusion in hydrated Na+-zeolite-4A using molecular dynamics simulations at 298 K for a range of hydration. It was observed that the self-diffusion coefficient of the mobile ions increased with hydration, in agreement with the results of conductivity experiments. Results demonstrate that the sodium ions in the Na(2) and Na(3) sites are preferentially hydrated at low hydration.

Solvent evaporation from hydrated peptides and model organic complexes formed by electrospray ionization was investigated using external ion source Fourier transform ion cyclotron resonance mass spectrometry. Slow evaporation of solvent from water clusters of biomolecules results in the formation of magic number clusters, clusters with increased stability. The experiments demonstrated other essential aspects of water structure around singly and multiply charged ions with low hydration levels.

Research was conducted to examine the three ordered hydration shells of aquated transition ions. A method that improves the spectral resolution and extends the distance range for detection of ordered solvent molecules surrounding a paramagnetic ion in frozen solutions using 1H electron-nuclear double-resonance spectroscopy is presented. The method allows enhanced resolution of the solvation structure within the second and third shells out to 7.5 angstrom from the paramagnetic divalent cation.

Aluminas and their surface chemistry play a vital role in many areas of modern technology. The behavior of adsorbed water is particularly important and poorly understood. Simulations of hydrated [Alpha]-alumina (0001) surfaces with ab initio molecular dynamics elucidate many aspects of this problem, especially the complex dynamics of water dissociation and related surface reactions. At low water coverage, free energy profiles established that molecularly adsorbed water is metastable and dissociates readily, even in the absence of defects, by a kinetically preferred pathway. Observations at higher water coverage revealed rapid dissociation and unanticipated collective effects, including water-catalyzed dissociation and proton transfer reactions between adsorbed water and hydroxide. The results provide a consistent interpretation of the measured coverage dependence of water heats of adsorption, hydroxyl vibrational spectra, and other experiments., Aluminas [that is, the various allotropic forms of [Al.sub.2][O.sub.3] (1)] are well known to have a broad technological significance. The surface chemistry of aluminas plays a key role in their [...]

Nuclear magnetic resonance data on O17 were gathered from hydrous silicate glass samples prepared at high temperatures and high pressures using solid-media apparatus. NMR spectra for O17 in dry and hydrous albite glasses did not show significant differences, whereas hydration of Na2Si4O9 glass leads to significant differences. The latter hydrated sample exhibits nonbridging oxygen (NBO) with considerable decline from peak intensity. This indicates a coordination environment of NBO atoms with water incorporation.

An 17O nuclear magnetic resonance study was conducted to examine the rate of exchange of water molecules from bulk solvent to the inner coordination sphere between hydrated aluminum complexes and bulk aqueous solution. It was observed that the lability of other inner-sphere oxygens are increased by a factor of almost equal to the 10(super 4) after the deprotonation of an inner-sphere water in Al(H2O)(sub 6)(super 3+)(aq). Findings also showed that the hydroxyl group has a labilizing effect on the other inner-sphere hydration waters in the complex.