1,721,013 research outputs found
Polarographic Investigations on Uranyl(VI) Complexes in Dimethylsulfoxide. 1. Monocarboxylic Ligands.
No full textThe formation of acetate, glycolate, chloroacetate and β-chloropropionate complexes of uranium(VI) in dimethylsulfoxide has been investigated by the polarographic method. 0.1M tetrabutylammonium perchlorate was used as supporting electrolyte. The 3:1 acetate and the 1:1 glycolate complexes give distinct cathodic waves; the polarographic behaviour allows to evidentiate also the 1:1 and 2:1 acetate, the 1:1 chloroacetate and β-chloropropionate complex formation. The formed complexes are stronger in DMSO than in water and the more so the harder the ligand. The (a)-character of uranyl ion is more marked in DMSO than in aqueous media
Preparation of high specific activity radiotracers for radioanalytical studies
No full textThis work reviews the more recent advances in this field carried out by the authors groups. High specific activity radiotracers are very suitable for studies related to the toxicol. impact of trace elements onto human health. In order to investigate the metabolic behavior of Low Level Exposure (LLE) to trace elements, it is necessary to carry out in-vitro and in-vivo expts. with tracers whose concn. is of the same order of magnitude as the present environmental exposure values (ng-μg/kg day). Prepns., sepns. and purifications of some no carrier added (NCA) radiotracers (48V, 95m,96Tc, 195m,g,197m,gHg, 199Au, 202Tl) produced by either cyclotron or nuclear reactor irradn., are presented and discussed. 23 Refs
Interaction of MO2++ ( M = U, Np, and Pu ) with Dicarboxylate Ligands Containing Other Donor Atoms.
No full textA quantílatitve study of the interaction ol uranyl(Vl), neptunyl(VI). and plutonyl(V) with oxydiacetate, iminodiacetate, thiodiacetate, and glutarate ligands has been carried out potentiometrically in aqueous solution with IM (Na,H)ClO4 at 20°C. Possible structures lor the varíous species present in solution are indicated on the basis ol an analysis ol the potentiometric data. The hehaviour o! the lour ligands towards the actinyl(VI) ions is discussed in terms ol their ditlerent central groups sncl their basicities. The stability constants show thst there are only minor ditlerences among the tendencies of the three actinyl(Vl) ions to form complexes wíth the ligands examined
Thermodynamic Properties of Actinide Complexes. IV. Thorium(IV)- and Uranyl(VI) - Malonate Systems.
No full textThe stability consts. and thermodn. of formation of Th4+ and UO22+ malonate complexes were detd. by potentiometric and calorimetric titrns. in 1.00 M NaClO4 at 25°. All complexes formed were stabilized by a large entropy gain. Stability const. values agreed with an ionic bonding model in which the malonate behaved as a bidentate ligand forming only chelate complexes
Interaction of MO2++ ( M = U and Pu ) Ions with 5-Sulphosalicylic Acid in Aqueous Solution.
No full textIn aq. solns. with ionic strength of 1M (Na+, H+, ClO4-) at 20°, the stability consts. were log β = 11.30, 2.32, 10.30, and 9.24 for H+ + L3- ↔ HL2- (H3L = 5-sulfosalicylic acid), H+ + HL2- ↔ H2L-, UO22+ + L3- ↔ UO2L-, and PuO22+ + L3- ↔ PuO2L-, resp
COMPLEXES OF TC-V AND TC-III WITH TRIDENTATE SCHIFF-BASES DERIVED FROM S-METHYL DITHIOCARBAZATE - CRYSTAL-STRUCTURES OF CHLORO[S-METHYL 3-(2'-HYDROXY-1-Synthesis and Characterization of paramagnetic triazenido-complexes of rhenium(III). The crystal structure of [ReCl2(p-MeC6H4N−N−NC6H4Me-p)(PPh3)2]
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Reactions of 5-Sulphosalicylic acid with lanthanides(III) and thorium(IV) in aqueous solution.
No full textThe complex formation equilibria of 5-sulphosalicylic acid with lanthanide(III) and thorium(IV) ions have been studied by means of potentiometric [H+] measurements in aqueous solution at 20 °C in a 1M (Na,H)ClO4 medium. The analysis of the potentiometric data referring to pH ranges where the hydrolytic reactions of metal ions are negligible indicates the formation of chelate complexes of the type LnL and LnL23- for the rare earth ions and ThL+ for the thorium ion. The ligand behaves as chelating agent through both the deprotonated carboxylate and phenolate groups. The stability constants of the complexes are reported and discussed
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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