Heavy Water Solutions Research Articles

A small-angle neutron scattering study of 2-butoxyethanol/D2O solutions

Small-angle neutron scattering (SANS) measurements have been performed in heavy water solutions of 2-butoxyethanol as a function of concentration and temperature. The results indicate that there exist some alcohol aggregation above a narrow concentration range (x=0.015–0.02, where x is the alcohol molar fraction) and the size of the aggregates increases with temperature taking a maximum value at a composition close to the critical concentration. The analysis of the size and of the absolute scattered intensity at q=0(I0) in terms of a microscopic model of aggregation, as well as the indications from other experiments, suggest that these aggregates are micelle-like structures.

Oxidation of tryptophan and N-methylindole by N3.cntdot., Br2.-, and (SCN)2.- radicals in light- and heavy-water solutions: a pulse radiolysis study

Reactions of N{sub 3}{sup {sm bullet}}, Br{sub 2}{sup {sm bullet}{minus}}, and (SCN){sub 2}{sup {sm bullet}{minus}} with tryptophan (TRPH) and N-methylindole (NMI) have been investigated in H{sub 2}O and D{sub 2}O solutions. The main transients produced were the TRP{sup {sm bullet}} radical and the TRPH{sup {sm bullet}+} radical cation from TRPH and the NMI{sup {sm bullet}+} radical cation from NMI. Their extinction coefficients ({epsilon}) as well as the rate constants for their formation and decay were determined in the pH range 3-10. The pK of the TRPH{sup {sm bullet}+} radical cation was confirmed to be 4.2 {plus minus} 0.1. These rate constants were within experimental error, independent of pH, and the differences between the rate constants in H{sub 2}O and D{sub 2}O were small. On the basis of the results, it was concluded that of the two possible reactions - electron or hydrogen atom transfer - the data are more consistent with electron transfer in all cases. However, secondary acid-base reactions have an important effect on the overall redox equilibria, especially with N{sub 3}{sup {sm bullet}}. Experimental data on these effects have also been obtained.

Solvent Isotope Effect on the Viscosity Coefficient B for Monovalent Ions in Water at 25 and 40°C

Abstract For heavy water solutions of LiCl, NaCl, KCl and CsCl at 25 and 40 C and KI at 25 °C the values of B(M + ) and B(X-) in the equation ]η/η0= 1 + A √c + [B(M + ) + B(X- )] c were determined under the conventional assumption B(K + ) = ß(Cl-). Here η0 is the viscosity of the solvent and c the molarity. The solvent isotope effect on the B values was found to be small. The B values for the medium-sized ions K + , Cs + , Br-, and I- were systematically more negative in heavy water than in light water. This is consistent with the idea that negative B values indicate the ability of the ion to break the structure of the water, the structure of heavy water being more developed than that of light water. For the tetraalkylammonium ions, Me4N + , Pr4N+ , and Bu4N + , on the other hand, the solvent isotope effect was small and random irrespective of the ion size. The temperature coefficients of B for the monatomic ions in heavy water were the same as for those in light water.

Solubilization tendency of 1-alkanols and hydrophobic interaction in sodium lauryl sulfate in ordinary water, heavy water, and urea solutions

The effects of 1-propanol, 1-butanol, 1-hexanol, and 1-octanol on the micellization parameters of sodium lauryl sulfate (NaLS) in heavy water (D 2 O) and in aqueous urea solutions, solvent systems with stronger and weaker hydrogen-bonded skeletal structures, respectively, than in ordinary water, have been determined at 25°C. We have also determined the transfer free energy of an alcohol from H 2 O to D 2 O and also to urea solutions by head space gas chromatography

Intercomparison of small biomolecules by gel filtration and small angle scattering

This paper describes how small angle neutron scattering (SANS) can be used to confirm that gel filtration results are free of dimerization effects. After characterization by analytical gel filtration, concentrated solutions (in heavy water, D 2O) of a cobra neurotoxin, a cytotoxin, and a cytotoxin analog are studied by SANS. Small differences in shape are shown to be discernible by means of least-square fits to ellipsoidal models. The parallel axis theorem is then invoked to assess dimerization levels statistically. The results are briefly discussed on the basis of function in relation to structure.

The cation structure of Ni-ATP in aqueous solution

The first-order difference method of neutron diffraction has been applied to a heavy water solution of 0.5 molal Ni-ATP. The results provide the first structural evidence that the Ni 2+ ion is directly bonded to the ATP molecule.

The Concept of Low Specific Activity Materials in Iaea the Transport Regulations

Abstract Low specific activity (LSA) materials are one of the main categories of radioactive materials transported. They consist essentially of physical and chemical concentrates of uranium and thorium, various types of solid and liquid waste and heavy water solutions. In 1988, some 30,000 tonnes of concentrated uranium are and chemical derivatives of uranium and some 35,000 cubic metres of waste were transported in France. The concept of LSA is based on an incorporation model in which it is assumed that it is highly improbable that an individual will inhale more than 10 mg of material in the event of an accident. Thus materials for which the Annual Limit of Intake (ALI) is greater than 10 mg are not considered to represent a significant potential danger. This hypothesis forms the general basis of systems of radiotoxicological classification of radionuclides of the Euratom type. The authors explore the validity of this model in the light of data on dust concentrations in air in different branches of indus...

Collision-induced Raman scattering from water and aqueous solutions

Short-lived, picosecond, collision-induced spontaneous Raman scattering processes in liquid water, heavy water, and aqueous solutions give rise to a totally featureless base line whose intensity, I{sub c}, decreases rapidly from {omega} = 0-6000 cm{sup {minus}1}. The well-known inter- and intramolecular vibrational scattering is separated from the collision-induced scattering by this base line; that is, the vibrational Raman scattering lies above it. The collision-induced base line for water is approximated in the Stokes spectrum, from 20 to 4500 cm{sup {minus}1} only, by the relation I{sub c} = k/{omega}{sup m}, where m, which rises slightly with temperature, equals about 1.2-1.3. However, more extensive data from 0.6 to 6000 cm{sup {minus}1}, obtained at 26{degree}C, produced the more general relation, ln I{sub c} = A exp(-B(ln (1 + {omega})){sup 2}), and Fourier transformation gives the average correlation time of the collision-induced polarization, C(t). C(t) = {integral} I{sub c} exp(i{omega}t) d{omega}. C(t) declines rapidly from unity and becomes zero just above t = 4 ps. Subtraction of the collision-induced base line in the low-frequency (< 350 cm{sup {minus}1}) region of water followed by Bose-Einstein reduction gives the intermolecular vibrational intensity, (I{sub T} - I{sub c})/(1 + n), where I{sub T} is the total scattering. Thismore » procedure, between 3 and 95{degree}C, yielded the first observation of an isosbestic point in the intermolecular vibrational spectrum, at about 128 cm{sup {minus}1}. A {Delta}H value of 2.3 {plus minus} 0.6 kcal/mol then resulted from computer analysis. The enthalpy change refers to the disruption of hydrogen bonds, for example, for a linear O-H{hor ellipsis}O hydrogen bond transforming to a weak, bifurcated hydrogen bond, in agreement with previous intramolecular vibrational {Delta}H measurements.« less

Aqueous tritium breeding blanket with natural lithium

An aqueous tritium breeding blanket concept with natural lithium has been proposed. Lithium oxide dissolved in pressurized heavy water forms a saturated solution of LiOD in the liquid phase and the remainder is suspended in the solution or forms a breeder solid skeleton. The tritium breeding ratio (TBR) and nuclear heating are calculated using a one-dimensional discrete ordinates transport code. The heavy water solution blanket with 4.3 wt% lithium, saturated solution at 373 K, may give a TBR of 1.07. A larger TBR can be obtained without a neutron multiplier or 6Li enrichment when the existence of dispersed particles is permitted in the solution. The TBR does not fall below unity until 6Li is depleted to less than 4 at%.

The structure of concentrated aqueous ammonium nitrate solutions

Neutron diffraction studies have been carried out on heavy water solutions of ammonium nitrate at two salt concentrations, 18 and 12 mol/kg–1. The first-order difference method of isotopic substitution was applied to both ND+4 and NO–3, thus enabling the determination of detailed structural information regarding the hydration of these ions. Both ions show relatively weak interactions with water. At the highest concentration, ca. 18 mol kg–1, there is evidence which demonstrates a direct interaction between the ND+4 and NO–3 ions.

Electrolytic Separation Factors for Oxygen Isotopes in Light and Heavy Water Solutions

The electrolytic separation factor, α, has been measured for 17O and 18O at Pt and Ni anodes in both light and heavy water solutions of as a function of current density. For oxygen‐17, isotopic separation effects were not observed, within the experimental uncertainty of ±2%, under all conditions studied. For oxygen‐18, three is a small difference of 2% in α values between Pt and Ni in both light and heavy water solutions, but there is no significant difference in α values between light and heavy water solutions. In light water solutions, the separation factor at Pt is small, for . This value agrees reasonably well with theoretical estimates.

Electronic structure of sulfanilamides

At present, about 30,000 derivatives of sulfanilamide are known. The establishment of a relationship between the structure of these compounds and their bacteriostatic activity is an urgent problem. In the present work, this problem is solved by means of NQR and NMR spectroscopy. Since the content of the /sup 14/N nuclei in these molecules is not high, to run the NQR, they used the double resonance method. Some samples of the sulfanilamides were studied by direct pulsed NQR method. The high resolution NMR spectra were run in heavy water solution on a RS-60MA spectrometer. All the measurements were carried out at 120/sup 0/K in the solid phase. The results of the calculation of eQq/sub zz/ for the NH/sub 2/ groups in the sulfanilamide residue are listed. To interpret the results by the MO LCAO method in the Hueckel approximation on the EC-1022 computer by a special FORTRAN program, they calculated the charged rho on an atom in the amino group with parameters of hetero atoms and coupling constants.

A Nuclear Reaction Analysis Technique to Determine The Penetration of Hydrogenic Species into Glasses Exposed to Leaching Solutions

AbstractNuclear reaction analysis is discussed as a method for determining the distribution of deuterium beneath the surfaces of glasses exposed to heavy water solutions for various times and temperatures. Limited examples of both conventional depth profiling for deuterium and a new technique for deuterium mapping are presented. The possible use of deuterium mapping for investigating the kinetics and mechanisms of the leaching of glasses is discussed.

Growth kinetics of lithium formate crystals in normal and heavy water solutions

Data on growth rates of hydrated lithium formate (LFM) and deuterated lithium formate (DLFM) crystal faces as a function of supersaturation at 307.65 K and observations of growth hillocks and liquid inclusions are presented and discussed. Following Bennema's modification of the BCF surface diffusion model as applied to crystal growth from solution, the values of growth parameters have been calculated and compared with the values reported for the growth of other substances. It was found that large liquid inclusions begin to appear at supersaturations σ > 0.0185 for LFM and σ > 0.0192 for DLFM, but tiny inclusions appear even at σ=0.0108.

Direct Determination of Ionic Solvation from Neutron Diffraction

Much information on ionic solvation in electrolyte solutions has been inferred from macroscopic thermodynamic and transport properties and from spectroscopy. These ion-water interactions can now be probed directly and unambiguously by neutron diffraction. Such measurements have been done with neodymium trichloride solutions in heavy water that are identical in every respect except the isotopic state of the neodymium ions; these experiments yield in a straightforward manner the distribution of oxygen and deuterium atoms from the water molecules in the first hydration sphere of the neodymium ion. Each ion is surrounded by 8.6 oxygen atoms at a distance of 2.48 angstroms and 16.7 deuterium atoms at 3.13 angstroms indicating a well-defined first hydration sphere of water molecules, the deuterium atoms pointing away from the cation.

Interaction induced light scattering spectra of amorphous solid and liquid NaOD heavy water solutions

Low frequency translational spectra of 15 M NaOD heavy water solutions are analyzed in both liquid and amorphous phases. Confirming the results of previous findings in KOH water solutions, the analysis suggests that the spectra reflect in both phases the translational density of the states of the system. In agreement with inelastic neutron scattering experiments, these can be thought of as propagating quasi-phonon excitations. A polarization analysis of the spectra based on the results of a model recently developed for orientationally disordered crystals, allows a separation between acoustic-like and optic-like modes and clearly shows the presence of a low frequency relaxation process. The presence of this feature is also related to radiation coupling coefficients of the acoustic-like modes.

Fourier Transform Infrared Spectra of Calf Thymus DNA and its Reactions with the Anticancer Drug Cisplatin

Fourier transform infrared (FT-IR) spectra of deoxyribonucleic acid (DNA) and its reaction products with the anticancer drug cis-Pt(NH3)2Cl2, cis-diamminodichloroplatinum (abbreviated cisplatin) in water and heavy water solutions or gels have been obtained and studied. The mid-IR spectra show considerable changes in the carbonyl (C=0) region and weaker, but significant perturbations in the sugar-phosphate absorption region (PO2−, OPC and COP). The carbonyl bands at 1710 and 1686 cm−1 of the control DNA in H2O and D2O, respectively, disappear and shift to lower frequencies in the spectra of cisplatin + DNA with a r = Pt/P = 0.2. Furthermore, the sugar-phosphate band at 1054 cm−1 of the C—O stretching vibration of the ribose-phosphate bond is reduced in intensity and slightly shifted to higher frequencies, indicating a reorientation of the phosphate group. In addition, the P—O stretching vibration frequency at 970 cm−1 is reduced in intensity on interaction with the drug. These changes depend to some extent on the water content in the control DNA and in the cisplatin + DNA complex. The water molecules in DNA in the presence of cisplatin reorganize themselves. The attack of the platinum drug at the N7 site of the guanine molecule in DNA exerts an effect on the DNA structure through a modification of the water average configuration and its stabilizing effect on the secondary structure.

Neutron diffraction study of aqueous transition metal salt solutions by isomorphic substitution

Experiments were initially carried out on 4.3 mol dm–3 MCl2(M = Ni or Mn) and 3.8 mol dm–3 M(ClO4)2(M = Ni or Cu) heavy-water solutions to test the method of isomorphic substitution and see whether Ni, Mn, Cu are suitable isomorphs. The results obtained for chloride solutions are compared with previous results obtained by the technique of isotopic substitution. Good agreement is found between the two techniques; the cation–oxygen and cation–deuterium distances are 2.09±0.02 and 2.69±0.02 Å, respectively. The influence of the different-sized Mn2+ and Ni2+ ions on the results is discussed.

Hydrogenation of ethylene on metal electrodes. Part 5.—Reduction of light ethylene on Pt in deuteroperchloric acid solution and the dual-pathway mechanism

Electroreduction of light ethylene on a platinum electrode was conducted in a heavy-water solution of deuteroperchloric acid. Deuterium-atom distributions in the product, ethane, support the previous conclusion that ethylene diffusion is rate-controlling at potentials less positive than ca. 100 mV, whereas the surface reaction is rate-controlling at more positive potentials where the Tafel line holds. The D-atom distribution in the latter potential region reveals double maxima at [2H2]- and [2H6]-ethanes. This distribution is explained by the dual-pathway mechanism which assumes two reaction rates for the step C2H4(a)+ H(a)⇌ C2H5(a). The difference in the reaction rate will be attributed to the difference in the adsorption state of C2H4(a) but not of H(a), since only the weakly adsorbed hydrogen atoms are active in the hydrogenation.Reduction of light ethylene with D2 on platinum in deuteroperchloric acid solution gives the same results.A computer simulation based on the above mechanism can reproduce quantitatively not only the present distributions but also others given in the literature, even those observed for the gas-phase heterogeneous reduction.

Ionic limiting partial molal volumes in various solvents

The existing methods for the separation of the limiting partial molal volumes of solutes are analysed, especially for non-aqueous electrolyte solutions. The method of Conway, Verrall and Desnoyers has been used for the calculation of ionic partial molal volumes at infinite dilution in various solvents and a comparative study of the text-decoration:overlineV0ion values obtained has been attempted. The calculated ionic limiting partial molal volumes of tetra-alkylammonium cations are practically identical in all organic solvents at the temperatures examined and differ greatly from the values in water and heavy water solutions. This fact provides additional evidence of the unsolvation of large tetra-alkyl-ammonium cations in organic solvents and the specific hydrophobic hydration of these cations in water and heavy water. The text-decoration:overlineV0R4N+ values for solutions in water and heavy water are considerably smaller than their appropriate values in organic solvents, due to the phenomenon of hydrophobic hydration of these cations in water and heavy water, when the organic chains of large tetra-alkyl-ammonium cations occupy intermolecular cavities in the water structure. The temperature dependence of the limiting partial molal expansibilities of tetra-alkylammonium cations in water and heavy water shows that Me4N+ and Et4N+ cations are “structure-breaking” ions in water and heavy water, but large tetra-alkylammonium cations, starting from Pr4N+, are “structure-making” ions. In accordance with the fact that ∂–ER4N+/∂T= 0 in organic solvents, these cations are neither “structure-makers” nor “structure-breakers” in organic solvents.