[en] This study is focussed on throwing light on the structures of uranium(VI) complexes with aliphatic (hydroxy-) carboxylic acids and on the structures of the sorption complexes on the iron mineral hematite in presence and absence of organic acids. The ternary system of hematite, uranium(VI), and organic ligand is very complicated, thus it is necessary to decompose it in binary systems. The results within these binary systems are used to better understand the complicated ternary system. Based on the comprehensive investigations on the aqueous uranium(VI) complexes, it is now possible to draw inferences from the structure of the carboxylic acid about the structure of the formed uranium(VI) complex in dependence of the pH. At first it has to be mentioned that uranium(VI) commonly gives pentagonal bipyramidal complexes. The pentaaquauranylion is formed by two axial oxygen atoms (O_ax) at a distance of 1.76 Aa and five equatorial oxygen atoms (O_eq) at 2.40 Aa stemming from coordinated water molecules. Due to complexation with organic ligands water is replaced by the ligand, thus the interatomic distances change. The results gained during all these investigations can help to better understand the interaction of uranium(VI) and carboxylic acids, and beyond that the sorption of uranium(VI) on hematite in the presence of carboxylic acids. Structures of the aqueous and sorption complexes are proposed. All these findings support the ongoing research on the transport behaviour of radioactive matter and may lead to more reliable risk assessment in connection with the permanent disposal of nuclear waste and the residues of uranium mining.

[en] This study was conducted to assess the new spineless mutants that previously induced through gamma radiation and hybridization techniques in the advanced generation for seed oil content and fatty acid profiles The obtained results cleared that oil percentages of all seven safflower mutants were increased than local variety Giza (1) and the new mutant hybrid 2 line (white petals) had the highest increase value of oil percentage (10%) but the mutant line M14 (dark red petals) had the lowest increase value of oil percentage (3.1 %) The mutant line M7 (yellow petals) had the highest value of total saturated fatty acid (40.38%), because it had the highest value of palmitic fatty acid (25.16%), comparing to 10.01% value for local variety Giza (1), followed by mutant line hybrid 2 (white petals) which had (39.88%) because it had the highest value of caprylic, capric, lauric, myristic and stearic fatty acids. All safflower mutant lines had higher value of oleic fatty acid than that of the local variety Giza (1) the two new safflower mutant lines M7 (yellow petals) and hybrid 2 (white petal) had the highest value of oleic fatty acid 41.22% and 39.88% respectively in comparison with 13.5% for local variety Giza (1), the obtained results are indicating to seed oil content negative correlation between oleic and linoleic acids

[en] The reaction of hyperazeotropic iodic acid-saturated nitric acid with short chain aliphatic iodides, nitrates, and acids was studied in order to determine the conditions for complete removal of organic materials from nitric acid systems. The aliphatic iodides are converted to the nitrates and the nitrates in strong HNO₃ are extensively converted into CO₂ and acids. The aliphatic acids are rather stable; acetic acid was unattacked by boiling in 20M HNO₃ and n-butyric acid was 80 percent unattacked. The dibasic acids oxalic and malonic are extensively attacked, but succinic acid is relatively stable. A wet oxidation method is successful in destroying acetic acid in 5 to 8M HNO₃. (U.S.)

[en] Potentiometric studies on some mixed ligand complexes of UO₂(VI) with ethylenediamine N,N' diacetic acid as primary ligand and succinic acid, malic acid, maleic acid, fumaric acid, malonic acid, adipic acid, itaconic acid, phthalic acid and mandelic acid as secondary ligands have been carried out employing modified form of Irving-Rossotti's pH titration technique. The study was carried out at three different temperatures, viz. 5deg, 25deg and 45degC and at fixed ionic strength of 0.2M KNO₃. Thermodynamic parameters, e.g. ΔG, ΔH and ΔS have been evaluated and further ΔG and ΔH values have been separated into their electrostatic components, ΔGe and ΔHe and cratic components, ΔGsub(c) and ΔHsub(c). The effect of change in dielectric constant and change in ionic strength of the medium have also been investigated. The sequence of stability constants has been correlated with the properties of secondary ligands. (author). 21 refs., 5 tabs

[en] An assay system has been developed based on automated radiometric quantification of ₁₄CO2 produced through oxidation of [1-₁₄C] fatty acids by mycobacteria. Two stains of M. tuberculosis (H37Rv and Erdman) and one of M. bovis (BCG) in 7H9 medium (ADC) with 1.0 microCi of one of the fatty acids (butyric, hexanoic, octanoic, decanoic, lauric, myristic, palmitic, stearic, oleic, linoleic and linolenic) were studied. Results previously published on M. lepraemurium (Hawaiian) were also included for comparison. Both strains of M. tuberculosis had maximum ₁₄CO2 production from hexanoic acid. Oxidation of butyric and avid oxidation of lauric acids were also found with the H37Rv strain but not with Erdman. In contrast, ₁₄CO2 production by M. bovis was greatest from lauric and somewhat less from decanoic acid. M. lepraemurium showed increasing oxidation rates from myristic, decanoic and lauric acids. Assimilation studies of M. tuberculosis H37Rv confirmed that most of the oxidized substrates were converted into by-products with no change in those from which no oxidation was found. These data suggest that the radiometric measurement of differential fatty acid metabolism may provide a basis of strain identification of the genus Mycobacterium

No abstract available

[en] Low-molecular-weight (LMW) organic acids occur widely in soils. Results in pure mineral systems and podzols suggest that LMW organic acids can promote the dissolution of Al from kaolinite, Al oxides and soils, but limited information is available concerning the role of these organic acids on Al mobilization in variable charge soils as yet. This paper deals with the effect of LMW organic acids on Al mobilization and mobilized Al distributed between the solution phase and exchangeable sites in two acidic variable charge soils. The results indicated that LMW organic acids accelerated Al mobilization through proton- and ligand- promoted reactions. The ability of different organic acids to mobilize Al followed the order: citric acid > oxalic acid > malonic acid > malic acid > tartaric acid > salicylic acid > lactic acid > maleic acid. This order was in general agreement with the magnitude of the stability constants of Al-organic acid complexes. The ratio of soluble Al to exchangeable Al also increased as the stability constants increased. These results showed that the organic acids with strong Al-complexation capacity were most effective in Al mobilization, whereas the weak organic acids promoted the retention of mobilized Al by the soil exchangeable sites. Increase in both organic acid concentration and solution pH promoted Al mobilization and also increased the ratio of soluble Al to exchangeable Al due to the increase in the concentration of the effective organic ligands, especially in the strong organic acid systems. These findings may have their practical significance for establishing more effective amelioration procedures for variable charge soils with increased acidity and higher mobility of Al

[en] The stability constants of binary and mixed methyl substituted malonic-dicarboxylic acid complexes of beryllium(II) have been determined. The substituted malonic acids are methylmalonic and dimethylmalonic and the dicarboxylic acids are succinic, itaconic maleic, glutaric and adipic. Beryllium(II) forms 1:1 and 1:2 complexes with all the ligands except glutaric and adipic in pH range 2.75-5.50. Ternary chelates of beryllium(II)-methylmalonic-dicarboxylic and beryllium(II)-dimethylmalonic-dicarboxylic acid systems have been studied. Ternary complex formation is discussed on the basis of ring size, nature of the substituents in the ligands, equilibrium constants and coordination chemistry of beryllium(II). It is observed that the complex stability and ligand basicity gives straight line relationship. (author)

[en] Decarboxylation by the reaction of SO₄^- radical with aliphatic and aromatic carboxylic acids has been examined. Most aliphatic acids undergo efficient decarboxylation by SO₄^- whereas their reactions with hydroxyl radical result in little decarboxylation. Aromatic acids decarboxylate to varying degrees depending on the other substituents. For example, benzoic and the phthalic acids undergo efficient decarboxylation, while o-toluic, p-hydroxybenzoic, and p-methoxybenzoic acid show only a small degree of decarboxylation. The findings support the conclusion that SO₄^- reacts by electron transfer oxidation while OH either adds or abstracts H. Decarboxylation by H₂PO₄ radicals was also examined in a few cases and found to be less efficient than that by SO₄^-

[en] Irving-Rossotti pH-titration technique has been used to determine the formation constants of some lanthanide-EDTA-O-O donor ternary complexes. The lanthanides used are La³⁺, Ce³⁺, Pr³⁺, Nd³⁺ and Sm³⁺ and the O-O donors are aliphatic and aromatic carboxylic acids, phenols and phenolic acids. The stability constants data have been used to study the electrostatic and astatistical factors involved during the formation of these mixed complexes. Two new stability parameters: 'relative stabilisation' and 'relative astatisticality' have been introduced. (author). 2 tabs