Tendenzen in der Entwicklung kontinuierlicher Verfahren zur Trennung stabiler Isotope

Im Laufe des letzten Vierteljahrhunderts unterlag das Interesse an der theoretischen und technischen Problematik der natürlichen Isotope einer ständigen Entwicklung.     

A System for Determination of Precise Isotopic Vapor Pressure Differences from —20 to 110 °C,including Temperature Control to 0·001 over that Range)

An experimental system for the precise measurement of small vapor pressure differences over the range —20 to 110°C is described.     

The New Kinetic Isotope Effect in the Ion Exchange and Liquid-Liquid Extraction Systems

The reaction kinetics of the isotope exchange and ion exchange process was studied on ion exchanger and liquid-liquid extraction systems. At least there were three exchangeable components in these systems (A, B and C); A and B are isòtopes of one element which have different concentrations (A ? B). It has been found that time function of the isotope separation factor has an extreme depending on the equilibrium, kinetic and hydrodynamic parameters.     

On the Use of δ – δ Diagram as Test for Equilibrium in Stable Isotope Geothermometry

The slope ≈ 1 arrays on δ – δ diagram are introduced as test for istotopic equilibrium between coexisting substance pairs out of closed system which are capable of providing an isotopic geothermometry. Some examples are given for illustrating the applicability of this graphical method.     

A Simple Method of the Flow Rate Determination of Fluids on the Basis of Diagrams obtained by a Radioactive Tracer Measurement

The simpliest and most convenient in a practical use method of the flow rate measurement, based on the tracer technique, is a such one, in which the passing time of the “tracer wave” is determined. The results are then obtained as a diagram of radiation intensity in the chosen points of the pipeline. The passing of the tracer over these points is marked on a recording tape in a form of the characteristic peaks. Depending on the kind of flow, the recorded peaks take the different shapes. In the first order they depend on the velocity profile in the pipe cross section. This differentiation of velocities causes that, when the distance between the detecting probe and the injecting unit increases, the tracer wave becomes more diluted, involving consequently a corresponding lengthening and flattening of peaks.     

Homogenitätsuntersuchungen an neutronenaktivierten Eisen-Mangan-Mischoxiden durch Messung der γ-Strahlung des 59Fe

In neutronenaktivierten Eisen-Mangan-Mischoxiden, deren Komponenten in Mengen gleicher Gröβenordnung vorlagen, wurde von einer statistisch ausreichenden Probenzahl die γ-Strahlung des ⁵⁹Fe gemessen. Zur Beurteilung der Homogenität warden die Standardabweichungen der Meβreihen mit der des Meβverfahrens verglichen und die Zahl der Meβwerte, die auβerhalb des Streu-bereichs des Meβverfahrens lagen, bestimunt. Es konnte gezeigt werden, daβ Messungen dieser Art zur Homogenitätsprüfung gut geeignet sind.     

Determination of the Parameter Ratio H0 2/K of Closed Thermal Diffusion Columns for Polynary Isotopic Mixtures

For the experimental determination of the H₀ ²/K ratio of the constants for prototype thermal diffusion columns from initial state mole fraction measurements there was a lack of sufficiently exact simple evaluation methods for polynary isotopic mixtures.

The investigation of mole fraction changes at closed ends obtained by numerical integration of the corresponding system of second order partial differential equations resulted in a concept of approximation which allows to utilize approximative analytical solutions originally developed for binary isotopic mixtures.

In the approximation the initial mole fractions are indirectly represented by the mean mass number of the initial mixture.

Thus, the measured mole fraction changes can be attributed to the difference between the actual mass number of the components and the mean mass number of the enclosed mixture. By simple regression analysis a partial derivative can be obtained which can be attributed to the approximative analytical solutions for binary mixtures.     

Isotope effects in the enzymatic oxidation of tryptamine to 3-indolyl-acetaldehyde

The reaction mechanisms of the enzymatic deamination of tryptamine catalysed by the enzyme monoamine oxidase (MAO, EC 1.4.3.4) were investigated using the kinetic isotope effect and solvent isotope effect methods. The numerical values of these deuterium effects in the (1S) and (1R) positions of tryptamine were determined using the non-competitive spectrophotometry. The deuterium-labelled isotopologue [(1S)-²H]tryptamine was obtained in two steps by enzymatic coupling of indole with S-methyl-l-cysteine in a deuterated medium followed by enzymatic decarboxylation of the resulting [2-²H]-l-tryptophan. [(1R)-²H]tryptamine was obtained by enzymatic decarboxylation of l-tryptophan in the fully deuterated medium.     

Break-Through Investigation on Uranium Isotope Separation in the System Uranyl Ion Solution Ti(III)-Cationic Resin

A break-through experiment on separation of uranium isotopes was carried out by use of a cation-exchange resin in Ti(III) form. By analyzing the experimental results the apparent equilibrium constants of the order K = 1·00021–1·00034 were determined.

The maximum value on the experimental curies of the isotopic ratio versus effluent volume was interpreted by considering two antagonistic isotope effects: one relatively large given by an exchange reaction between U(IV) in resin and U(VI) in solution and another smaller given by the reduction reaction of U(VI) with Ti(III). The difference of the equilibrium constants of the these two isotope effects as a function of temperature was used for the determination of the apparent thermodynamic values of the resultant process, determined experimentally: ΔH⁰ = 0.8542 cal mol^?1 and ΔS⁰ = 3.33×10^?3cal°K^?1.     

Effect of uniaxial pressure on the Raman spectra of fluoro perovskites containing manganese with sodium or potassium

ABSTRACT

Perovskite structured mixed metal fluorides containing manganese/sodium or potassium have been synthesized in pure form by a greener precipitation route and characterized by high-resolution powder X-ray diffraction and Raman spectroscopy techniques. While all the reflections in the powder X-ray diffraction pattern of potassium manganese fluoride could be indexed in cubic symmetry with a = 4.1889 Å, sodium manganese fluoride showed reflections at positions typical of orthorhombic symmetry (Pnma space group) with a = 5.751, b = 8.008, and c = 5.548 Å. Potassium manganese fluoride in powder form showed bands at 209, 291, 386, 558, 621, and 733 cm^?1 in the Raman spectrum at room temperature. All these bands disappeared and second-order band at 1151 and 1298 cm^?1 emerged when the powders were compacted under pressure ranging between 1 and 4 tons (uniaxial). A similar change was noticed for sodium manganese fluoride in which bands at 1099, 1149, 1203, and 1286 cm^?1 were observed for the compacted samples. The response of the vibrational modes of these compounds to uniaxial pressure revealed the existence of large structural disorder in them. Additionally, the need for the extreme care to collect and interpret Raman data of polycrystalline samples of these systems has been illustrated through this study.     

Isotope variations of hydrogen,carbon and nitrogen in florae from the Schirmacher Oasis,East Antarctica

Comparative biochemical and isotope-chemical investigations of cosmopolitical plants open up ways of obtaining parameters from different parts of the Earth which are characterised by variations in the habitat due to different environments. As an Antarctic oasis, the Schirmacher Oasis disposes of adequate favourable ecological conditions for the growth of lower plants.

In the present paper, results of isotope studies of lichens, mosses and algae of the Schirmacher Oasis are given and peculiarities of the habitats which influence the isotope contents of the plants are discussed.     

Human Respiration Under the Condition of Severe Anemia Investigated with the Aid of Fractionation Effects of Oxygen Isotopes

Abstract

The dependence of overall fractionation effect of respiration between ¹⁶O₂ and ¹⁶O¹⁸O (δ_IU) on varying levels of hemoglobin concentration within blood is investigated. Experiments are carried out on 6 healthy humans and 6 patients suffering from various degrees of chronic anemia.

δ_IU-values of anemic patients are decreased towards 0‰ meaning that within anemia rates of ¹⁶O_2? and ¹⁶O¹⁸O-transport are aligned together more than they are under healthy conditions.

On the basis of a resistance model of respiration, it is concluded that within anemia the entire oxygen transport system is more limited by blood flow than it is in healthy humans. This limitation starts to influence respiration far above a hemoglobin concentration of 8 g/100 ml.     

Deuterium and Oxygen-18 in Surface Waters of GDR draining to the Baltic Sea

A general view is presented of deuterium and ¹⁸O measurements of water samples collected at running and standing surface waters in German Democratic Republic. The values confirm earlier observations that the surface waters are influenced by evaporation with respect to the isotopic composition of groundwater. Nevertheless, stronger evaporation effects are restricted to larger lakes. The amount of surface water discharge from GDR to the Baltic Sea and the δD and δ¹⁸O values are discussed. The river Oder provides about 90% of the whole surface run-off. The other watercourses to the coast are unimportand. The mean heavy isotope content of surface run-off was calculated to be ?8.3‰ for δ¹⁸O and ?61‰ for δD (vs. SMOW), respectively.     

The Influence of Addition of Inorganic Carbonates on the Relative Volatility Factor of Light and Heavy Water at Temperatures Close to the Isotope Effect Inversion Temperature

The influence of Na₂, CO₃, K₂CO₃, and Li₂CO₃ addition on the relative volatility factor α of light and heavy water ai temperatures close to the isotope effect inversion temperature has been investigated. The measurements for Na₂CO₃ and K₂CO₃ solutions have been made in the temperature range. 100–330 °C at various salt concentrations. In the case of Li₂CO₃ temperature range and concentration was limited by the solubility of this salt. The factor α was determined by analysis of gas and liquid phases at equilibrium. Data on pure waters obtained by other investigators are listed for comparison. The temperature dependence of factor α for salt solutions and pure waters is presented in the form of equations derived from experimental data.