Showing papers on "Uranyl published in 1971"
TL;DR: In this paper, a new reagent, 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol, is described for the spectrophotometric determination of uranium(VI).
169 citations
87 citations
TL;DR: In this paper, the typical low-energy spectra of the uranyl complexes were interpreted by using group theory and qualitative molecular orbital theory, and a comparative study of the effects of ligation on the spectrum showed that the observed facts can be rationalized by means of one possible identification scheme.
Abstract: The typical low‐energy spectra of the uranyl complexes—both in solution and in the solid state—are interpreted by using group theory and qualitative molecular orbital theory. A comparative study of the effects of ligation on the spectrum shows that the observed facts can be rationalized by means of only one possible identification scheme. The band system situated at 20 000–22 000 cm−1 is due to a 1Σg+ → 1Φg transition, while the band system at 22 500–27 000 cm−1 is due to a 1Σg+ → 1Δg transition.
71 citations
TL;DR: The chemical estimation of the phospholipid loss during the dehydration supported the ultrastructural findings, and Indium trichloride showed a fixative action similar to that of uranyl salts as determined by electron microscopy.
70 citations
TL;DR: In this article, the interaction of iron(III) and uranyl ions with dissolved silica is studied by a spectrophotometric technique, and the interaction with iron is studied as a function of the degree of polymerization of the silica.
49 citations
42 citations
TL;DR: Electron-dense crystals formed in plant roots exposed to uranyl acetate have been used to identify binding sites and to follow the pinocytotic uptake of uranyl in the oat rootcap.
Abstract: Electron-dense crystals formed in plant roots exposed to uranyl acetate have been used to identify binding sites and to follow the pinocytotic uptake of uranyl in the oat rootcap. Before uranyl enters the protoplast, the plasmalemma is greatly dilated. After uranyl is sequestered in vacuoles, the tonoplast is similarly dilated.
39 citations
34 citations
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TL;DR: A series of complexes of uranyl β-diketones with pyridine N-oxide and its 4-substituted derivatives (4z·PyNO) have been isolated by solvent extraction as mentioned in this paper.
TL;DR: In this article, the ionization potentials of Ca, Sr, Ba and U salt spray additives in fuel-rich, premixed H2+ O2+ N2 flames have been quantitatively examined.
Abstract: Total positive ion concentrations Ni produced from Ca, Sr, Ba and U aqueous salt spray additives in fuel-rich, premixed H2+ O2+ N2 flames have been quantitatively examined. For the alkaline earths M, the present findings are consistent with the following scheme: M(OH)2+ H ⇌ MOH + H2O, MOH + H ⇌ MO + H2, MO + H ⇌ MOH++ e–, with M(OH)2 the dominant neutral species in the region of measurement. Through a second law procedure, the ionization potentials of CaOH, SrOH and BaOH are deduced to be 5.9 ± 0.1, 5.55 ± 0.1 and 5.25 ± 0.1 eV respectively. With uranium also, the evidence suggests a gaseous scheme, equivalent overall to the above, viz., UOnHm+ 3H UOn–1H+m–1+ e–+ H2+ H2O, with M probably the uranyl species UO2, i.e., H2UO4+ 3H HUO+3+ e–+ H2+ H2O, with D°0(HO—UO3H)+I.P. (HUO3)= 950 ± 40 kJ mol–1, and I.P. (HUO3)< 3.9 eV.
When any of these metals are present in the flame together with an alkali metal, Ni may be much greater than predicted if the two additives behaved independently. This effect is consistent with a catalysis of the alkali metal ionization rate by the second additive; the results reveal the possibility of a heterogeneous as well as a homogeneous route.
TL;DR: In this article, the solvent effect on the adduct formation constant was taken into account in connection with the activity; the activity coefficients of each species in various solutions were calculated from the molar volume and the solubility parameter.
Abstract: Addition compound formation between uranyl bis-thenoyltrifluoroacetonate (UO2A2) and tributyl phosphate(S) was studied by a partition method, using uranium-237 as the tracer. The formula of the adduct complex was shown to be UO2A2·S. The solvent effect on the adduct formation constant was taken into account in connection with the activity; the activity coefficients of each species in various solutions were calculated from the molar volume and the solubility parameter. The formation constants based on the molar fraction, Kx, in a number of solvents were pre-estimated, employing logKx=7.08 in carbon tetrachloride as a reference. They are in agreement with the observed values. The formation constant in terms of activity was found to be constant logKS°=5.77±0.30. A correlation between the formation constants of the two adducts, UO2A2·S and ZnA2·S, was demonstrated.
Journal Article•
01 Jan 1971-Science reports of the Research Institutes, Tohoku University. Ser. A, Physics, chemistry and metallurgy
TL;DR: In this article, the solvent effect on the adduct formation constant was taken into account in connection with the activity; the activity coefficients of each species in various solutions were calculated from the molar volume and the solubility parameter.
Abstract: Addition compound formation between uranyl bis-thenoyltrifluoroacetonate (UO2A2) and tributyl phosphate(S) was studied by a partition method, using uranium-237 as the tracer. The formula of the adduct complex was shown to be UO2A2·S. The solvent effect on the adduct formation constant was taken into account in connection with the activity; the activity coefficients of each species in various solutions were calculated from the molar volume and the solubility parameter. The formation constants based on the molar fraction, Kx, in a number of solvents were pre-estimated, employing logKx=7.08 in carbon tetrachloride as a reference. They are in agreement with the observed values. The formation constant in terms of activity was found to be constant logKS°=5.77±0.30. A correlation between the formation constants of the two adducts, UO2A2·S and ZnA2·S, was demonstrated.
TL;DR: In this article, the relative rates for uranyl fluorescence quenching by aliphatic alcohols (methyl, ethyl, n-propyl, isopropyl, N-butyl, Sobutyl) were measured under various conditions, showing the involvement of both acid-dependent and acidindependent processes.
Abstract: The relative rates for uranyl fluorescence quenching by aliphatic alcohols (methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and s-butyl alcohols) were measured under various conditions. The rates were increased in proportion to the perchloric acid concentration at pH <1, whereas the rates were smaller and nearly constant at the pH’s between 1–4; thus showing the involvement of both acid-dependent and acid-independent processes. Though the rates for both processes changed with the change in the alcohol structure (the polar substituent effect), the ratio of the two rate constants was nearly constant. The inhibitory effects of cupric ions (as a scavenger for the one-equivalent redox intermediates) suggested that the acid-dependent quenching process involves a two-equivalent redox or two consecutive one-equivalent redox steps between the same partners. The mechanisms of these quenching processes are discussed.
TL;DR: In this article, the thenoyltrifluoroacetone (TTA) chelate of uranyl ion between aqueous perchlorate medium and thirteen organic solvents was investigated.
Abstract: The extraction equilibria were investigated of the thenoyltrifluoroacetone (TTA) chelate of uranyl ion between aqueous perchlorate medium and thirteen organic solvents. The extracted species was shown to be UO2A2. The solubility parameter of the chelate was estimated from the partition data and it was confirmed that the relationship lgP M=n lgP HA+const. holds for the present system. When the extraction constant (K ex) is considered in relation to the distribution coefficients, theK ex values are expected to be constant under certain conditions for all of the solvents; the lgK ex values were found to be constant (lgK ex=−2.85±0.17).
TL;DR: In this paper, the energy levels of ammonium uranyl fluoride (NH4)3UO2F5] have been established for the first time from the investigations of Raman, infrared, fluorescence and electronic absorption spectra of the compound.
TL;DR: In this paper, a quantitative order of the electronic effects of the β-ketoenolate substituents was derived to derive the relative importance of π-interaction in the uranyl complexes.
TL;DR: In this article, the Calvin-Bjerrum pH titration technique has been adopted for the determination of proton affinity constants and the stability constants of the metal chelates.
TL;DR: Two complexes of formula UO2(Et2NCSe2)2·L (L = Ph3PO or Ph3AsO) have been prepared; the arsine oxide dertivative is a pentagonal-bipyramidal complex, the four selenium atoms and the ligand oxygen atom lying in the plane normal to the uranyl group.
Abstract: Two complexes of formula UO2(Et2NCSe2)2·L (L = Ph3PO or Ph3AsO) have been prepared; the arsine oxide dertivative is a pentagonal-bipyramidal complex, the four selenium atoms and the ligand oxygen atom lying in the plane normal to the uranyl group.
TL;DR: A simple chromatographic procedure for the separation of trace amounts of uranium has been developed as discussed by the authors, which is applied to the determination of micrograms of uranium in rocks and underground waters.
TL;DR: Complex uranyl fluorides of the general formulae BH 2 [UO 2 F 4 ]· n H 2 O, M II [BH 2 ]· NH 2 O and M 2 I [M 2 I] have been isolated in pure state as discussed by the authors, where B = organic diamine base, viz biguanide and phenyl biguanides, and M II = Ba 2+ and bivalent complex cations.
TL;DR: It is shown that not only the rate of uptake but also the final distribution level is reduced, and various hypotheses for the explanation of the effects are presented.
Abstract: Uranyl ions have long been used as inhibitors of mono-accharide uptake by yeast. It is shown here that not only the rate of uptake but also the final distribution level is reduced. Monosaccharides transported by the specific carrier are most affected by 5×10−4
m uranyl nitrate while higher concentrations are less inhibitory. Monosaccharides transported by the universal carrier are affected by uranyl ions only to a lesser degree. Various hypotheses for the explanation of the effects are presented.
TL;DR: In this article, the authors studied the kinetics of the exchange reaction between uranyl nitrate-organic phosphate complex and excess phosphate by NMR line broadening and found that the activation energy was the same, within experimental accuracy for all three phosphates in all the solvents investigated 9 kcal/mole.
TL;DR: In this paper, the dissociation constants for pyridoxine hydrochloride have been determined both potentiometrically and spectrophotometrinically at an ionic strength of 0·50M-KCl and at 30°.
Abstract: The dissociation constants for pyridoxine hydrochloride have been determined both potentiometrically and spectrophotometrically at an ionic strength of 0·50M-KCl and at 30°. The interaction of the uranyl ion with pyridoxine had been studied spectrophotometrically in the pH range 1–12, at an ionic strength of 0·50M-KCl, and at 30°. It is shown that three mononuclear complexes are formed in the pH range 1–7·5, the pK values for the three stepwise instability constants being 11·49, 8·48, and 3·76. Data in the pH range 7·5–12 could not be interpreted adequately.