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Enrique J. Baran

Bio: Enrique J. Baran is an academic researcher from National University of La Plata. The author has contributed to research in topics: Infrared spectroscopy & Raman spectroscopy. The author has an hindex of 32, co-authored 589 publications receiving 6392 citations. Previous affiliations of Enrique J. Baran include Technical University of Dortmund & National Scientific and Technical Research Council.


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TL;DR: The interaction of the VO2+ cation with homocysteine, was investigated by electron absorption spectroscopy in aqueous solution at different metal-to-ligand ratios and suggests that the interaction is different from that found in the case of cysteine and occurs through pairs of amino and carboxylate groups of the amino acid.
Abstract: The interaction of the VO2+ cation with homocysteine, was investigated by electron absorption spectroscopy in aqueous solution at different metal-to-ligand ratios. The direct reduction of vanadate(V) solutions with homocysteine was also investigated. The results suggest that the interaction is different from that found in the case of cysteine and occurs through pairs of amino and carboxylate groups of the amino acid. The interaction of VO2+ with homocystine, the oxidation product of homocysteine, was also analyzed. The interest of the results in relation to vanadium metabolism and detoxification is briefly discussed.

4 citations

Journal ArticleDOI
TL;DR: In this article, the mean amplitudes of vibration and thermodynamic functions of TeF5Cl have been calculated in a wide temperature range, using known spectroscopic data, and comparisons with some related species are made.
Abstract: Mean amplitudes of vibration and thermodynamic functions of TeF5Cl have been calculated in a wide temperature range, using known spectroscopic data. The results are briefly discussed and comparisons with some related species are made.

4 citations

Journal ArticleDOI
TL;DR: In this article, the complex [ReO(Me4tu)4]3+, with Me4tu = tetramethylthiourea, was characterized in nonaqueous media.
Abstract: The complex [ReO(Me4tu)4]3+, with Me4tu = tetramethylthiourea, is characterized in nonaqueous media. Its structure is studied in acetonitrile solution by 1H and 13C NMR and its electrochemical behavior in the same solvent is analyzed by means of cyclic voltamperometric measurements. Heteronuclear correlation and variable temperature NMR experiments suggest that the complex ion shows a similar structure in solution and in the solid state. At low temperatures (below 0°C) free rotation of the dimethylamine groups around the thiocarbonyl carbon-nitrogen bond is restricted and the dissolved complex adopts the rigid structure observed in the solid state. Cyclic voltamperometric results suggest that the redox behavior of this compound can be explained through an ErCiEr mechanism (a chemical reaction coupled between two electron-transfer reactions). An initial one electron reduction of the complex from Re(V) to Re(IV) followed by an irreversible chemical reaction, leads to a new electroactive species of Re(IV)*, ...

4 citations


Cited by
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Journal ArticleDOI
TL;DR: Aqueous V(III) Chemistry 877 6.2.1.
Abstract: 6.1.2. Aqueous V(III) Chemistry 877 6.1.3. Oxidation State of Vanadium in Tunicates 878 6.1.4. Uptake of Vanadate into Tunicates 879 6.1.5. Vanadium Binding Proteins: Vanabins 879 6.1.6. Model Complexes and Their Chemistry 880 6.1.7. Catechol-Based Model Chemistry 880 6.1.8. Vanadium Sulfate Complexes 881 6.2. Fan Worm Pseudopotamilla occelata 883 7. Vanadium Nitrogenase 883 7.1. Nitrogenases 883 7.2. Biochemistry of Nitrogenase 884 7.3. Clusters in Nitrogenase and Model Systems: Structure and Reactivity 885

1,184 citations

Journal ArticleDOI
TL;DR: In this paper, the perovskite structure is used to illustrate the relationship of structure to composition, and the history of the fundamental science of structure-to-composition is described.
Abstract: Starting with the history of the fundamental science of the relation of structure to composition delineated completely by Goldschmidt, we use the perovskite structure to illustrate the enormous pow...

998 citations

Journal ArticleDOI
TL;DR: Using a variety of approaches, researchers have begun to unravel the exquisite control mechanisms exerted by cells specialized for CaOx formation that include the machinery for uptake and accumulation of Ca, oxalic acid biosynthetic pathways, and regulation of crystal growth.
Abstract: Calcium oxalate (CaOx) crystals are distributed among all taxonomic levels of photosynthetic organisms from small algae to angiosperms and giant gymnosperms. Accumulation of crystals by these organisms can be substantial. Major functions of CaOx crystal formation in plants include high-capacity calcium (Ca) regulation and protection against herbivory. Ultrastructural and developmental analyses have demonstrated that this biomineralization process is not a simple random physical-chemical precipitation of endogenously synthesized oxalic acid and environmentally derived Ca. Instead, crystals are formed in specific shapes and sizes. Genetic regulation of CaOx formation is indicated by constancy of crystal morphology within species, cell specialization, and the remarkable coordination of crystal growth and cell expansion. Using a variety of approaches, researchers have begun to unravel the exquisite control mechanisms exerted by cells specialized for CaOx formation that include the machinery for uptake and accumulation of Ca, oxalic acid biosynthetic pathways, and regulation of crystal growth.

993 citations

01 Jan 1993
TL;DR: This work states that for many years, bone was defined anatomically and examined largely in a descriptive manner by ultrastructural analysis and by biochemical and histochemical methods, but now, complemented by an increased knowledge of molecular mechanisms that are associated with and regulate expression of genes encoding phenotypic compone...
Abstract: I. Introduction A FUNCTIONAL relationship between cell growth and the initiation and progression of events associated with differentiation has been a fundamental question challenging developmental biologists for more than a century. In the case of bone, as observed with other cells and tissue, the relationship of growth and differentiation must be maintained and stringently regulated, both during development and throughout the life of the organism, to support tissue remodeling. For many years, bone was defined anatomically and examined largely in a descriptive manner by ultrastructural analysis and by biochemical and histochemical methods. These studies provided the basis for our understanding of bone tissue organization and orchestration of the progressive recruitment, proliferation, and differentiation of the various cellular components of bone tissue. Now, complemented by an increased knowledge of molecular mechanisms that are associated with and regulate expression of genes encoding phenotypic compone...

982 citations

Journal ArticleDOI
TL;DR: A complete chemical and physicochemical characterization of chitin, chitosan and their derivatives is not possible without using spectroscopic techniques, so this review focuses on the application of Spectroscopic methods for the structural analysis of these compounds.
Abstract: Chitin, the second most important natural polymer in the world, and its N-deacetylated derivative chitosan, have been identified as versatile biopolymers for a broad range of applications in medicine, agriculture and the food industry. Two of the main reasons for this are firstly the unique chemical, physicochemical and biological properties of chitin and chitosan, and secondly the unlimited supply of raw materials for their production. These polymers exhibit widely differing physicochemical properties depending on the chitin source and the conditions of chitosan production. The presence of reactive functional groups as well as the polysaccharide nature of these biopolymers enables them to undergo diverse chemical modifications. A complete chemical and physicochemical characterization of chitin, chitosan and their derivatives is not possible without using spectroscopic techniques. This review focuses on the application of spectroscopic methods for the structural analysis of these compounds.

848 citations