摘要:

After discovery of uranium fission by Hahn and Strassmann in Berlin-Dahlem at the end of 1938, nuclides regarded as isotopes of transuranium elements were shown to be those of lighter elements. Only the uranium isotope 239 was confirmed. As beta emitter it was likely to be the mother substance of at least one transuranium isotope. Separation had failed, possibly because incorrect analytical behaviour had been assumed. Radioactive recoil, being independent of chemical properties, served successfully to isolate the neptunium isotope 239.

ISSN:0021-1915    

DOI:10.1080/10256019008624331

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The discovery and the chemistry of neptunium is described. Improvements in redox reactions, analytical determinations and environmental research work are discussed.

ISSN:0021-1915    

DOI:10.1080/10256019008624332

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Ion mobilities of carrier-free239Np(V) have been measured in aqueous solutions, T = 298.1 (1) K. Ion mobilities of239NpO2+and its dependencies on pH of acidic inert electrolytes have been measured. In alkaline solutions the stoichimetric hydrolysis constants of NpO2(OH) as well as NpO2(OH)2−have been obtained. Complex formations of239Np(V) with oxalate, tartrate, sulphate, acetate and citrate ligands have been studied in neutral solutions.

ISSN:0021-1915    

DOI:10.1080/10256019008624333

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

From the comparison of terrestrial atmospheric Xe with the primordial Xe (solar, AVCC), a strange component with a fine structure at132Xe and131Xe have been found. It was shown that the isotopic composition of this component can be explained neither by mass fractionation of primordial Xe, nor by an admixture of fission products of known nuclei. An analogous Xe was extracted at a low temperature from substances of the natural nuclear reactor, fine-grain samples from Colorado type deposits, ordinary pitchblendes and samples from the epicenter of a A-bomb explosion. It was proved that the strange Xe is a result of different migration rates of β-radioactive Xe precursors which are fission fragments. It is quite possible that the strange component of atmospheric Xe originated as a result of global neutron-induced fission processes during early stages of geological history of the Earth.

ISSN:0021-1915    

DOI:10.1080/10256019008624334

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The selective flux of sulfur during magma emplacement is proposed to explain some abnormal δ34S data from granitic and basaltic rocks. It is assumed that on the one hand a quasi-equilibrium isotope fractionation exists between sulfate and sulfide during magma cooling, and on the other hand a non-equilibrium fractionation occurs between the fluxed sulfur and the magmatic sulfur. The results show that at high fO2,34S is preferably enriched in sulfate with decreasing temperature, without a corresponding depletion of sulfide in34S. The δ34S value of solidified rocks is then significantly shifted in the positive direction due to the selective degassing or assimilation. Conversely, at low fO2,34S is preferably depleted in sulfide as temperature declines, while a corresponding34S-enrichment in sulfate does not occur. As a consequence, δ34S value of the rocks is driver in the negative direction.

ISSN:0021-1915    

DOI:10.1080/10256019008624335

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The paper reports on the results of210Pb measurement in sediment cores from the Baltic Sea. The models used for the interpretation are derived and discussed. In general, the sedimentation parameters calculated with different models are consistent. However, parameters of cores independently taken on same stations partly show clearly differing values. The reasons of this observation has to be analysed by further studies.

ISSN:0021-1915    

DOI:10.1080/10256019008624336

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The major contribution to population exposure from natural radiation arises from the inhalation of the decay products of radon. Substantial surveys are being conducted by several investigators to estimate the indoor and outdoor exposure nationally and to discover regional variations. In this work, radon concentration in the indoor and outdoor air was determined using the can technique and employing CR-39 solid state nuclear track detector for lengthy exposures. The range of radon-222 activity in this survey was 54 … 299 pCi · m−3in Cairo, 22 … 171 pCi · m−3in Alexandria and 89 … 370 pCi · m−3in Asiut. Measurements carried out in Aswan and Sinai ranged between 98 … 411 pCi · m−3. Values of indoors and outdoors radon concentrations were found to vary with geographic location, season and height above ground. Further work is going on to study the different parameters affecting the levels of the environmental radon.

ISSN:0021-1915    

DOI:10.1080/10256019008624337

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

An avalanche-like increase of research activities in the field was caused by the spectacular announcements and publications about the observation of nuclear fusion processes during the infusion of deuterium into metals. Though, the original claims by Fleischmann and Pons concerning the observation of macroscopic amounts of heat so far seem not to be approved in a quantitative manner by other groups, there are indications for the start of a new interesting field of research at the border between nuclear physics and solid state physics – investigations of nuclear fusion processes in condernsed matter. First conclusions drawn here about possible mechanisms of such processes have to be considered neither complete nor final.

ISSN:0021-1915    

DOI:10.1080/10256019008624338

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Potassium zinc hexacyanoferrate, zirconium titanium phosphate (ZTP) and zirconium phosphate silicate (ZPS) ion exchangers were prepared. They were used as cation exchanger to study the uptake of Eu from sulphuric acid solutions. The distribution coefficient data was used to calculate the formation constant of the Europium sulphate complex.

ISSN:0021-1915    

DOI:10.1080/10256019008624339

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Two samples of potassium zinc hexacyanoferrate were prepared using two different ratios of the initial materials. The distribution coefficient of Eu3+on the two samples was determined. The effect of the cation concentration in the aqueous phase on the adsorption of Eu3+was also studied. The mechanism of the exchange process was described on the light of the data obtained, and the equilibrium constant of the exchange reaction was also calculated.

ISSN:0021-1915    

DOI:10.1080/10256019008624340

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor