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PubMed1988

The effect of saline loading on uranium-induced acute renal failure in rats.

Studies were performed to examine the effect of saline loading on uranium-induced acute renal failure (ARF) in rats. Forty-eight hours after the i.v. injection of uranyl acetate (UA, 5 mg/kg), inulin clearance rate (Cin) decreased to approximately 43% of the control value in water drinking rats (P less than 0.005). Animals receiving continuous isotonic saline infusion following UA showed higher urine flow and Cin (60% of control, P less than 0.01), and lessened intratubular cast formation when compared with water-drinking ARF rats. A short-term saline infusion following UA did not attenuate the decline in Cin (43% of control). An inverse relationship was found between Cin and the number of casts (r = -0.75, P less than 0.01). Multiple regression analysis showed that standardized partial regression coefficient is statistically significant between Cin and cast formation (-0.69, P less than 0.05), but not between Cin and tubular necrosis (-0.07, P greater than 0.05). Renin depletion caused by DOCA plus saline drinking did not attenuate the decline in Cin in ARF (47% of control). No significant difference was found in urinary uranium excretion between water-drinking and saline-infused ARF rats. The findings suggest that continuous saline infusion following UA attenuates the decline in Cin in ARF rats; and that this beneficial effect of saline loading is associated with lessened cast formation rather than with suppressed renin-angiotensin activity or enhanced urinary-uranium excretion.

Acute Kidney Injury↗
PubMed2007

Radiation: facts, fallacies and phobias.

There is frequent debate in the media and the scientific published reports about the use of radiation for diagnosis and treatment, the benefits and risks of the nuclear industry, uranium mining and the storage of radioactive wastes. Driving this debate is increasing concern about reliance on fossil fuels for power generation for which alternatives are required. Unfortunately, there is generally a poor understanding of the relevant basic sciences compounded by widespread irrational fear of irradiation (radiation phobia). Radioactivity, with special reference to uranium and plutonium is simply described. How radiation affect tissues and the potential hazards to individuals and populations are explained. The origins of radiation phobia and its harmful consequences are examined. Whether we like it or not, Australia is heavily involved in the uranium industry by virtue of having one-third of the world's known reserves, exports of which are worth approximately $470m annually. As this paper has been written as simply as possible, it may also be of interest to readers who may have had little scientific training. It may be downloaded from the web using references provided in this article. It is concluded that ignorance and fear are major impediments to rational debate on radiation issues.

Australia↗
PubMed1999

Solid-phase extraction of ultratrace uranium(VI) in natural waters using octadecyl silica membrane disks modified by tri-n-octylphosphine oxide and its spectrophotometric determination with dibenzoylmethane.

A simple and reliable method for rapid extraction and determination of uranium in natural waters using octadecyl-bonded silica membrane disks modified with tri-n-octylphosphine oxide (TOPO) and spectrophotometry with dibenzoylmethane is presented. Extraction efficiency and the influence of sample matrix, type, and optimum amount of extractant, flow rates, and type and minimum amount of organic eluent were evaluated. The maximal capacity of the membrane disks modified by 50 mg of TOPO was found to be 4033 micrograms of uranium. The limit of detection of the proposed method is 100 ng/1000 mL. The method was applied to the extraction and determination of uranium in natural waters.

Benzoates↗
PubMed1991

A cytogenetic study of men occupationally exposed to uranium.

Blood lymphocyte cultures from two groups of workers occupationally exposed to uranium were examined for asymmetrical chromosome aberrations and sister chromatid exchanges (SCEs). Significant increases in both cytogenetic endpoints were seen. For dicentrics this appeared to be particularly associated with exposure to soluble uranium. The external radiation exposure experienced by these men was insufficient to explain the increase in dicentrics, and irradiation of lymphocytes by internally deposited uranium would have been minimal. As the SCEs were also raised, the genotoxic effect is likely to be due to the chemical nature of the compound. The increase in frequency of dicentrics associated with smoking was greatest in the group with exposure to soluble uranium suggesting some interaction between the two clastogens. No such interactive effect was seen for SCE frequencies, in which increases attributable to smoking were similar in the worker and control groups.

Adult↗
PubMed2000

The related compounds MThTe3 (M = Mn, Mg) and ACuThSe3 (A = K, Cs): syntheses and characterization.

Single crystals of MnThTe3 (1) and MgThTe3 (2) grow as small black plates from the stoichiometric reaction of the elements, the former at 1,000 degrees C and the latter at 900 degrees C with the aid of a Sn flux. Both compounds crystallize in the space group Cmcm of the orthorhombic system with four formula units in cells of dimensions a = 4.2783(6) A, b = 13.8618(11) A, and c = 9.9568(15) A for 1 and a = 4.2854(6) A, b = 14.042(2) A, and c = 9.9450(14) A for 2 at T = 153(2) K. KCuThSe3 (3) forms as red blocks from a stoichiometric mixture of K2Se, Cu, Th, and Se at 800 degrees C, and CsCuThSe3 (4) forms as yellow blocks from a stoichiometric mixture of Cs2Se3, Cu, Th, and Se at 850 degrees C. Compounds 3 and 4 also crystallize in the space group Cmcm of the orthorhombic system with four formula units in cells of dimensions a = 4.1832(8) A, b = 14.335(3) A, and c = 10.859(2) A for 3 and a = 4.2105(7) A, b = 15.715(3) A, and c = 10.897(2) A for 4 at 153(2) K. Compounds 1 and 2 are isostructural with each other as well as with several uranium analogues and comprise pseudolayered structures with slabs of corner-shared MTe6 octahedra alternating with slabs of cap- and edge-shared ThTe8 bicapped trigonal prisms. The slabs are bonded together through the sharing of edges and vertices of the various polyhedra to form three-dimensional structures. Compounds 3 and 4 are two-dimensional layered structures that are closely related to 1 and 2. In 3 and 4, ThSe6 octahedra form the same slabs as MTe6 in 1 and 2 and Cu atoms occupy the tetrahedral holes in the layers. Alkali metal cations occupy bicapped trigonal prismatic sites between the layers. Neither structure type has short Q-Q interactions, and therefore the oxidation states of all atoms are straightforwardly assigned on the assumption of Th4+. Magnetic susceptibility measurements on compound 1 show a ferromagnetic transition at 70 K and a magnetic moment of 5.9(2) muB per Mn ion, indicating low-spin Mn2+.

Journal Article↗
PubMed2003

The resonance Raman effect of uranyl formate in dimethyl sulfoxide.

The resonance Raman scattering spectra of uranyl formate (UO(2)(HCOO)(2)) in dimethyl sulfoxide ((CH(3))(2)SO, DMSO) have been measured under laser excitation of the uranyl ion in resonance with the 1Sigma(g)(+)-->(1)Phi(g) Laport forbidden f-f electronic transitions (ranging from 510 to 450 nm) by using ten output lines with wavelength ranging from 528.7 to 454.5 nm of the argon-ion laser at room temperature. The observed resonance excitation profile resembles the vibronic structure of the electronic absorption spectrum (ABS) but does not completely superimpose on it. Such a discrepancy is quantitatively explained by the interference effect, which occurs noticeably in the UO(2)L(2) (L=NO(3), CH(3)COO, Cl or HCOO)-DMSO system. Transform theory that makes use of the electronic ABS of the resonant electronic state has been applied to predict the Raman excitation profile (REP) of the uranyl totally symmetric stretching vibrational mode. Comparing the experimental REP with the transform theory prediction, it is found that the resonance Raman intensities of this stretching mode depend mainly on the vibronic interaction (non-Condon effect) in excited electronic states. Reliable value of the nuclear displacement on going the 1Sigma(g)(+)-->(1)Phi(g) electronic transition and the amount of charge transferred from the ligand to uranium of uranyl ion both in the ground and excited states are obtained. Elongation of the U-O equilibrium bond length due to the electronic transition is related to the magnitude of the change in the excitation profile, and has linear relation to the change in the amount of charge transferred from the ligand to uranium of uranyl ion in UO(2)L(2) type uranyl compounds in DMSO.

Dimethyl Sulfoxide↗
PubMed2001

Synthesis, structure, and properties of Cs(4)Th(4)P(4)Se(26): a quaternary thorium selenophosphate containing the (P(2)Se(9))(6-) anion.

Orange crystals of Cs(4)Th(4)P(4)Se(26) were grown from the reaction of (232)Th and P in a Cs(2)Se(3)/Se molten salt flux at 750 degrees C. Cs(4)Th(4)P(4)Se(26) crystallizes in the orthorhombic space group Pbca with the unit cell parameters: a = 12.0130(6), b = 14.5747(7), c = 27.134(1) A; Z = 8. The compound exhibits a three-dimensional structure, consisting of dimeric [Th(2)Se(13)] polyhedral units. The two crystallographically independent, nine-coordinate, bicapped trigonal prismatic thorium atoms share a triangular face to form the dimer, and each dimer edge-shares two selenium atoms with two other dimers to form kinked chains along the [010] direction. While this structure shares features of the previously reported Rb(4)U(4)P(4)Se(26), including phosphorus in the 5+ oxidation state, careful inspection of the structure reveals that the selenophosphate anion that knits the structure together in three directions in both compounds is a unique (P(2)Se(9))(6-) anion. The formula may be described best as [Cs(2)Th(2)(P(2)Se(9))(Se(2))(2)](2). The (P(2)Se(9))(6-) anion features a nearly linear Se-Se-Se backbone with an angle of 171 degrees and Se-Se distances that are approximately 0.2-0.3 A longer than the typical single Se-Se bond. Magnetic studies confirm that this phase contains Th(IV). Raman data for this compound is reported, and structural comparisons will be drawn to its uranium analogue, Rb(4)U(4)P(4)Se(26).

Journal Article↗
PubMed2001

Time scales for sorption-desorption and surface precipitation of uranyl on goethite.

The sorption of uranium on mineral surfaces can significantly influence the fate and transport of uranium contamination in soils and groundwater. The rates of uranium adsorption and desorption on a synthetic goethite have been evaluated in batch experiments conducted at constant pH of 6 and ionic strength of 0.1 M. Adsorption and desorption reactions following the perturbation of initial states were complete within minutes to hours. Surface-solution exchange rates as measured by an isotope exchange method occur on an even shorter time scale. Although the uranium desorption rate was unaffected by the aging of uranium-goethite suspensions, the aging process appears to remove a portion of adsorbed uranium from a readily exchangeable pool. The distinction between sorption control and precipitation control of the dissolved uranium concentration was also investigated. In heterogeneous nucleation experiments, the dissolved uranium concentration was ultimately controlled by the solubility of a precipitated uranyl oxide hydrate. The X-ray diffraction pattern of the precipitate is characteristic of the mineral schoepite. Precipitation is kinetically hindered at low degrees of supersaturation. In one experiment, metastable sorption controlled dissolved uranium concentrations in excess of the solubility limit for more than 30 d.

Adsorption↗
PubMedDate not supplied

On the chemiluminescence in the oxidation of tetravalent uranium to the uranyl ion by dimethyldioxirane.

The reaction of the tetravalent uranium [U(IV)] with dimethyldioxirane (DMD) in strongly acidic water-acetone solutions is accompanied by chemiluminescence (CL) in the visible (Vis) and infra-red (IR) regions. At least three independent reaction pathways are involved in the U(IV)-DMD oxidation: the first entails the non-chemiluminescent oxidation of U(IV) to the uranyl ion (UO(2) (2+)); the second involves the catalytic decomposition of DMD by U(IV) to afford singlet oxygen, as manifested by its characteristic IR-CL; and in the third process, slow Vis-CL (510-540 nm) is emitted, following DMD consumption.

Epoxy Compounds↗
PubMed1989

Treatment of experimental acute uranium poisoning by chelating agents.

Sixteen chelating agents were examined to determine their relative efficacy as antidotes in acute uranyl acetate intoxication in mice after subcutaneous administration. Chelators were administered intraperitoneally to male Swiss mice at a dose equal to one-fourth of their respective LD50 and the therapeutic effectiveness was calculated. Eight compounds resulted in a significant enhancement of the survival rate: Tiron, gallic acid, DTPA, p-aminosalicylic acid, sodium citrate, EDTA, 5-aminosalicylic acid and EGTA. Therapeutic indices (TI) were then determined for these chelating agents. Tiron (TI: 158), gallic acid (TI: 116) and DTPA (TI: 44.9) were the most effective antidotes. In subsequent experiments, uranyl acetate dihydrate was administered subcutaneously (10 mg/kg) in a 24 hr excretion and distribution study. The previous eight chelators were given intraperitoneally ten min. after the uranium administration. 5-Aminosalicylic acid and tiron were consistently the most effective in increasing the urinary and faecal excretion of uranium respectively. A decrease of the uranium concentration in kidneys and bone was also noted with tiron. Tiron appears to be the most effective agent of those tested in the prevention of acute uranium intoxication.

Animals↗
PubMed2005

Remediation and recovery of uranium from contaminated subsurface environments with electrodes.

Previous studies have demonstrated that Geobacter species can effectively remove uranium from contaminated groundwater by reducing soluble U(VI) to the relatively insoluble U(IV) with organic compounds serving as the electron donor. Studies were conducted to determine whether electrodes might serve as an alternative electron donor for U(VI) reduction by a pure culture of Geobacter sulfurreducens and microorganisms in uranium-contaminated sediments. Electrodes poised at -500 mV (vs a Ag/AgCl reference) rapidly removed U(VI) from solution in the absence of cells. However, when the poise at the electrode was removed, all of the U(VI) returned to solution, demonstrating that the electrode did not reduce U(VI). If G. sulfurreducens was present on the electrode, U(VI) did not return to solution until the electrode was exposed to dissolved oxygen. This suggeststhat G. sulfurreducens on the electrode reduced U(VI) to U(IV) which was stably precipitated until reoxidized in the presence of oxygen. When an electrode was placed in uranium-contaminated subsurface sediments, U(VI) was removed and recovered from groundwater using poised electrodes. Electrodes emplaced in flow-through columns of uranium-contaminated sediments readily removed U(VI) from the groundwater, and 87% of the uranium that had been removed was recovered from the electrode surface after the electrode was pulled from the sediments. These results suggest that microorganisms can use electrons derived from electrodes to reduce U(VI) and that it may be possible to remove and recover uranium from contaminated groundwater with poised electrodes.

Biodegradation, Environmental↗
PubMed1995

PBK modeling for metals. Examples with lead, uranium, and chromium.

Physiologically-based models for metals differ in several key respects from models for organic compounds. Although sequestration by binding to specific metal-binding proteins in liver, kidney, and red cell may be important, neither the magnitude and pattern of metabolism nor potential accumulation in fat is a component of models of metal kinetics. In addition, the long residence times of bone-seeking elements require that bone turnover and metabolism be incorporated into physiologically-based models for these elements. Three mechanism (rapid exchange at bone/blood interfaces, trapping or incorporation with forming bone and loss with resorbing bone, and slow exchange throughout the total bone volume) are potentially important in the overall interchange of bone-seeking elements between blood and bone. Three examples are given of applications of physiologically-based kinetic models for the bone-seeking elements lead, chromium, and uranium to assist in answering practical questions relating to bioavailability, distribution, and data interpretation.

Animals↗
PubMed2003

Characterisation and dissolution of depleted uranium aerosols produced during impacts of kinetic energy penetrators against a tank.

Aerosols produced during impacts of depleted uranium (DU) penetrators against the glacis (sloping armour) and the turret of a tank were sampled. The concentration and size distribution were determined. Activity median aerodynamic diameters were 1 microm (geometric standard deviation, sigma(g) = 3.7) and 2 microm (sigma(g) = 2.5), respectively, for glacis and turret. The mean air concentration was 120 Bq m(-3), i.e. 8.5 mg m(-3) of DU. Filters analysed by scanning electron microscopy (SEM) and X ray diffraction showed two types of particles (fine particles and large molten particles) composed mainly of a mixture of uranium and aluminium. The uranium oxides were mostly U3O8, UO2.25 and probably UO3.01 and a mixed compound of U and Al. The kinetics of dissolution in three media (HCO3-, HCl and Gamble's solution) were determined using in-vitro tests. The slow dissolution rates were respectively slow, and intermediate between slow and moderate, and the rapid dissolution fractions were mostly intermediate between moderate and fast. According to the in-vitro results for Gamble's solution, and based on a hypothetical single acute inhalation of 90 Bq, effective doses integrated up to 1 y after incorporation were 0.54 and 0.56 mSv, respectively, for aerosols from glacis and turret. In comparison, the ICRP limits are 20 mSv y(-1) for workers and 1 mSv y(-1) for members of the public. A kidney concentration of approximately 0.1 microg U g(-1) was predicted and should not, in this case, lead to kidney damage.

Aerosols↗
PubMed2006

Carbonate effects and pH-dependence of uranium sorption onto bacteriogenic iron oxides: kinetic and equilibrium studies.

The removal of U(VI) from groundwaters by adsorption onto bacteriogenic iron oxides (BIOS) has been investigated under batch mode. The adsorbent dosage, the uranium concentration, the concentration of carbonate and the use of a real groundwater spiked with uranium comprised the examined parameters. In addition, the effect of pH was examined in two different water matrixes, i.e., in distilled water and in real groundwater. Equilibrium studies were carried out to determine the maximum adsorption capacity of BIOS and the data correlated well with the Langmuir and Freundlich models. The presence of carbonate affected adversely the adsorption of U(VI) onto BIOS. The maximum adsorption capacity of BIOS was 9.25 mg g(-1) at 0.1mM carbonate concentration and decreased to 6.93 mg g(-1) at 0.5mM carbonate concentration, whereas at carbonate concentration of 2mM practically no adsorption occurred. The data were further analyzed using the pseudo-second order kinetic equation, which fitted best the experimental results. The initial adsorption rate (h) was found to increase with decreasing the concentration of carbonate in all cases. When experiments were accomplished in the absence of carbonate, the pH values did not have an effect on the adsorption of U(VI). However, the extent of U(VI) adsorption was strongly pH-dependent when the experiments were carried out in the real groundwater. The maximum adsorption capacity increased sharply as the pH decreased and optimum removal was obtained in the pH range 3.2-4.0, thus bacteriogenic iron oxides can found application in the removal of U(VI) by adsorption from low pH or low carbonate waters.

Adsorption↗