Mixtures Of Heavy Water Research Articles

Polarized Neutron Scattering from Dynamically Polarized Targets in Biology

This paper discusses polarized neutron scattering from clusters of polarized proton spins in solid material which provides a new contrast variation method. Frozen solutions of apoferritin and of the large subunit of Escherichia coli ribosomes in a mixture of heavy water and deuterrated glycerol hae been studied at the conditions of dynamic nuclear spin polarization (H = 2.5 T, T {lt} 1 K, 4-mm microwave irradiation). The three basic scattering functions of contrast variation were derived by varying polarized neutron scattering with the polarization of target nuclei. They agree with results obtained form neutron scattering in H{sub 2}O/D{sub 2}O mixtures at room temperature. Furthermore, the proton spins appear to be polarized uniformly, at least to a structural resolution of 40 {Angstrom}. This is an important prerequisite for the in situ structure determination of macromolecular labels in larger host particles.

Dynamic nuclear polarisation of biological matter.

Polarised targets as used in high energy physics experiments may be of considerable interest in biological structure research using polarized neutrons. So far, this promising method has been facing difficulties in getting reasonable polarization of the target nuclei. We report on a polarized "frozen spin" target which has been prepared from an enzyme dissolved in a mixture of heavy water and deuterated propanediol doped with a completely deuterated paramagnetic radical. Clusters of 700 protons defined by the structure of lysozyme embedded in a fully deuterated matrix were polarized to 75% within an hour by 4 mm microwave irradiation in a magnetic field of 2.5 tesla at a temperature of 0.3 K. The polarisation behaviour of biological targets can be compared to the best frozen spin target materials in high energy physics research.

Study of phase separation of a critical binary fluid in gel

We have employed small angle neutron scattering to study the phase separation process of a binary fluid in a permanently cross-linked polymer gel. The fluid trapped in a 7 wt. % polyacrylamide network is a mixture of heavy water 2-6 lutidine near its critical composition, This single phase homogeneous mixture at room temperature exhibits a cloud point transition upon heating. Due to the difference in the affinity of polymer to heavy water and 2-6 lutidine, the polymer network may be considered to exert a type of chemical random field on the trapped binary fluid. Our results were analyzed in terms of the random field Ising model and a more recent theory of de Gennes.

Neutron diffraction study of light and heavy water mixtures at 25 °C

Neutron diffraction data of very high statistical accuracy for four mixtures of light and heavy water containing 0.01%, 35.79%, 67.89%, and 99.75% deuterium are presented. The dynamic corrections described in a preceding article yielded a self-consistent static coherent structure function for heavy water. For the other mixtures an empirical correction method was used. The four total structure functions were analyzed to yield the three partial structure functions aOO(k), aOH(k), and aHH(k). The function aOO(k) is not significantly different from previously obtained x-ray diffraction results. The partial structure functions for hydrogen interactions will provide a sensitive test for proposed models of liquid water.

A Design Study of the Neutron Irradiation Facility for Boron Neutron Capture Therapy

A design study of the neutron irradiation facility for boron neutron capture therapy was performed using two-dimensional transport calculations. Dose depth distributions in a phantom head were calculated for various neutron energies. The epithermal neutrons having the energies between 10 eV and 0.5 keV are suitable for the therapy. To obtain the epithermal neutron beam, the neutrons leaking downward through the central hole of the annular core TRIGA reactor were moderated through a mixture of heavy water with aluminum whose volume ratio is 15:85. Bismuth and lithium fluoride tile was used to remove gamma rays and thermal neutrons from the beam. Iron, borated polyethylene, and lead were used as the shield surrounding the moderation layer. When the epithermal neutron column is used, the maximum usable depth and irradiation time are 6.9 cm and 7.25 h, respectively, at a 2-MW level.

Measurement of the hydrogen isotope effect on muonic oxygen x-ray intensities

The hydrogen isotope effect recently observed at the Los Alamos Meson Physics Facility (LAMPF) has been qualitatively confirmed. However, we observe a significantly smaller effect. Recent communications from the LAMPF group indicate that their results are now consistent with this smaller effect. We find the dependence of the effect on the light-water concentration in a light- and heavy-water mixture is linear.

Избыточное поглощение ультразвука в смеси воды и тяжелой воды

The excess ultrasonic absorption in binary mixtures of H2O-D2O has been evaluated by calculating the relaxation time τ=β0(ηV+3/4μ) and relaxing compressibility βr=β0[1|4/3(μ/ηV)]−1. There is good agreement between the computed and the experimental value of excess absorption using the above values of βtr and τ. τ and ΔF obtained from this method compare favourably with the values of the same parameters reported by Koret al. in the lower-temperature range. In the higher-temperature range the difference is as high as 10%. This is because the values of β∞ are assumed to be temperature independent by Koret al. ΔV/V is found to be independent of temperature and concentration of D2O supporting the assumption of earlier workers.

Ultrasonic study in binary mixtures of water and heavy water

An experimental study of ultrasonic absorption in water and heavy-water mixtures has been made at three concentrations from 10 to 50 ‡C. Because of the close similarities in the behaviour of the aforesaid components an ideal mixing has been assumed. To explain the excess absorption, Hall’s two-state model of structural absorption has been used. The results are as expected, and the experimentally observed excess and the theoretically calculated structural absorption are in close agreement with each other in the present temperature range. The values δV/V = 0.47 and Β∞ = 17·10−12 cm2/dyn have been assumed for computations.

A butanol polarized deuteron target: II. Polarization at 50 kOe

Deuteron polarization up to 26% was obtained in 98% perdeuterated 1-butanol and heavy water mixtures, doped with porphyrexide, at 1 K and 50 kOe. The polarization of the 2% unsubstituted protons in the same samples reached 86%.

A butanol polarized deuteron target I. Polarization at 25 kOe

Dynamic deuteron polarizations up to 22% have been obtained in samples of a few cm 3, made out of perdeuterated 1-butanol and heavy-water mixtures, doped with porphyrexide-a free radical-at temperatures down to 0.5 K, in a magnetic field of 25 kOe. The polarization of the few remaining protons (about 2%) was found to reach 80%. Different ways of calibrating the deuteron polarization, including 600 MeV proton scattering, yielded the same results.

Ionization of Some Weak Acids in Water—Heavy Water Mixtures1

Measurements of the dissociation constants of ammonium, hydrazoic acid, and chloroacetic acid were made in mixtures of light and heavy water by the glass electrode method. The results obtained are in good agreement with previously recorded values. (P.C.H.)

HYDROGEN PEROXIDE AND ITS ANALOGUES: VIII. EXCESS FUNCTIONS FOR THE BINARY SYSTEMS H2O–H2O2 AND D2O–D2O2

Recent volumetric and calorimetric data have been used to calculate the excess functions for mixtures of water and hydrogen peroxide over the entire concentration range. The results are compared with those for the corresponding deuterium compounds. The existing calorimetric and vapor-pressure measurements are not comprehensive nor accurate enough to support discussion of the finer details of the excess quantities. A maximum in the excess-volume curves, presumably related to the formation of the compound H2O2.2H2O, persists in the liquid mixtures over an appreciable temperature range above the melting point of that compound. A possible crystal structure is proposed for the latter.New density determinations were carried out on mixtures of heavy water and deuterium peroxide at 0° and 20 °C. and the effect of deuterium peroxide on the temperature of maximum density of heavy water was measured and compared with that of deuterated alcohols. It is concluded that the structure of liquid water is easily penetrated by hydrogen peroxide molecules.

Recherches Sur La Thermodiffusion En Phase Liquide: Thermodiffusion De L'eau Lourde

Experiments on thermodiffusion of mixtures of heavy water are described. The Soret coefficient D′ / D is found to be independent of composition. Its value (7.10 −5 ± 3.10 −5 temp −1 ) is discussed in connection with the kinetic theory developed in a previous paper of this serie.

Influence of Deuterium Oxide on Growth and Morphology of Lactobacilli

The biological interest in deuterium oxide or heavy water cannot be overlooked because all living cells require water for growth. Barnes reported that Spirogyra showed some unusual and interesting effects when grown in low concentrations of deuterium oxide and that these concentrations had a stimulating effect on the growth of Euglena. Harvey and Taylor recorded that when luminous bacteria were incubated in tubes containing mixtures of heavy water and ordinary water, the amount of oxygen used by the bacteria was in proportion to the percentage of heavy water in the mixture. Also the luminescence of the bacteria was diminished when exposed to low concentrations of heavy water. Richards observed the growth of Saccharomyces cerevisió in weak concentrations of deuterium oxide which he claimed accelerated growth and development, as opposed to its lethal effect in higher concentrations. In order to obtain data on the reaction of other microbiologic forms, we conducted experiments on the growth and morphology of 8 strains of lactobacilli exposed to various concentrations of this water-compound. We are obligated to Professor H. V. Moyer of the Department of Chemistry for the deuterium oxide. The heavy water was mixed with Difco dehydrated whey broth so that the broth contained concentrations of 0.13, 0.7, and 5.0% deuterium oxide. The control broth was prepared with distilled water which was devoid of all deuterium oxide. The various lots of broth, in 10 cc. portions, were sterilized in sealed glass tubes at 15 pounds pressure for 20 minutes. In studying the effect of deuterium oxide, 1 cultures each of L. czcidoplzilus and L. bulgaricus were used. Each culture n-as inoculated into the various lots of esperimental medium, using 0.1 cc. of an actively groving broth culture for each tube. The cultures were incubated at 37C. −\t 12-hour intervals for a 60-hour period, 1 CC. was withdrawn from each tulx and pour plates were prepared with tomato-juice agar, using dilutions of 1:1000, 1:10:000 and 1:100,000 of the cultures.

The Determination of Acidity in Heavy Water Mixtures

The Determination of Acidity in Heavy Water Mixtures