نتایج جستجو برای: natural uranium

تعداد نتایج: 489999  

2014
Gang Song Qiuping Zhu Minxing Lu Diyun Chen Yongheng Chen

Large amounts of uranium waste rocks and tailings resulting from the exploitation and treatment of uranium ore at the Northern Guangdong mine (South China) have been accumulated in dams (tailing ponds). To reduce the dispersion of natural radionuclides into the environment, some dams were revegetated with arbor, bush and sward. Besides these plants, Miscanthus floridulu is the dominant plant gr...

H. Garshasbi, N. Alirezazadeh,

Background: Measurement of back ground concentration of uranium in drinking water is very important for many reasons, specially, for human health. The uranium concentration in drinking water in many counties is a matter of concern for clinical and radioactive poisoning. Materials and Methods: The uranium concentration in drinking water is determined using laser flourimatric uranium analyzer. Fo...

2010
Y. Y. EBAID

Uranium is a rare earth element found in the earth’s crust with an average of 3 ppm. Natural uranium is a mixture of three radioactive isotopes U (99.27% abundance), U (0.72% abundance) and U (0.0054% abundance). It has been employed over the last seven decades as a source of energy and weapon. Enrichment processes were widely practiced to produce the necessary fuel. On the other hand, depleted...

Journal: :Analytical sciences : the international journal of the Japan Society for Analytical Chemistry 2004
Ali Reza Ghiasvand Elham Mohagheghzadeh

A simple and efficient method for the selective separation and preconcentration of uranium(VI) using homogeneous liquid-liquid extraction was developed. Tri-n-octylphosphine oxide (TOPO) and tri-n-butylphosphate (TBP) were investigated as complexing ligands, and perfluorooctanoate ion (PFOA-) was applied as a phase separator agent under strongly acidic conditions. Under the optimal conditions (...

2008
Houston G. Wood Alexander Glaser

Different enrichment processes have been used historically to produce highly enriched uranium (HEU) for weapon purposes. The most relevant ones are the gaseous diffusion process and the gas centrifuge. The two exploit different physical principles to separate isotopes of different molecular weight. It could therefore be expected that HEU might carry an isotopic signature that is unique to the e...

2006
Giovanni La Macchia Marcin Brynda Laura Gagliardi

Use of sterically hindered ligands to maintain the integrity of normally unstable chemical entities is a widespread technique in modern synthetic chemistry. Bulky aryl and alkyl substituents have been designed to stabilize sensitive compounds, such as main-group-element dimers with multiple bonds, including the alkyne analogues of heavier Group 14 elements. 3] This methodology was recently empl...

2005
J. F. Kalinich

This paper discusses the development of and proposed enhancements to a colorimetric test for the detection of uranium in biological samples such as urine. The goal of this work is to develop a technique for the detection of uranium that could: 1) be conducted rapidly and accurately; 2) would not require extensive sample preparation; 3) would not require expensive or complicated instrumentation;...

2009
Masao Tamada

Total amount of uranium resource in seawater is one thousand times of that in terrestrial ores. A polymeric adsorbent being capable of collecting uranium in seawater was developed in early 1980s, since uranium is inevitable resource to operate atomic power plants. This adsorbent fabric was synthesized by radiation-induced graft polymerization which could impart a desired functional group into f...

2008
YOUNG IN KIM DOHEE HAHN

It is generally recognized that the spent fuel discharged from nuclear power plants constitutes the main contribution to nuclear waste. The management of spent fuel from nuclear power plants differs depending on the perspectives and scenarios posed by the countries directly concerned. However, there is a general consensus on the need for a deep geological repository and a reduction in the burde...

2010
Alfred Russell Francis Bacon

From Becquerel's uranium rock to Newton's proverbial rock and Fleming's serendipitous observation of penicillin, the way science is done has come to be associated often with a romanticized but highly suspect notion of objectivity. This may very well be the effect on science of inductivism and the bold claim of the proponents of inductivism that science could not possibly lead to any kind of tru...

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