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.

The interaction of the vanadyl(IV) cation with phytic acid.

Abstract: The interactions of VO2+ with phytate to form both soluble and insoluble complexes, have been studied by electronic absorption spectroscopy. A soluble 1∶1 VO2+: phytate complex is formed at pH <1. At higher pH-values insoluble complexes are produced. Two different solid complexes, obtained respectively at pH=2 and 4, were isolated and characterized. The maximal bonding ratio of VO2+: phytate was found to be 4, on the basis of a pH binding profile.

Die Divanadate des Thoriums

Abstract: Es wird gezeigt, das ThV2O7 in zwei kristallinen und einer amorphen Modifikation vorkommt Das strukturchemische Verhalten dieser Formen wird an Hand von thermischen, rontgenographischen und spektroskopischen Messungen erlautert Die Infrarotspektren der drei Phasen werden eingehend besprochen The Divanadates of Thorium It is shown that ThV2O7 appears in three polymorphic forms, two of them are crystalline and the third is amorphous The structural behaviour of these forms is analysed with the aid of thermal, x-ray, and spectroscopic methods The infrared spectra of the three modifications are discussed in detail

Crystal structure and ir-spectrum of lithium citrate monohydrate, li(c6h7o7).h2o

Abstract: The crystal structure of Li(C6H7O7) · H2O has been determined by single-crystal X-ray diffractometry. It crystallizes in the triclinic space group P 1 with Z = 2. The structure was solved by direct and Fourier methods and refined to R1 = 0.031. Some comparisons with related structures are made. The infrared spectrum of the salt was recorded and briefly discussed. Kristallstruktur und IR-Spektrum von Lithium-Citrat-Monohydrat, Li(C6H7O7) · H2O Die Kristallstruktur von Li(C6H7O7) · H2O wurde rontgenographisch an Einkristallen bestimmt. Es kristallisiert in der triklinen Raumgruppe P 1 mit Z = 2. Die Struktur wurde mit direkten und Fourier Methoden gelost und zu R1 = 0.031 verfeinert. Es werden einige Vergleiche mit verwandten Strukturen gemacht. Das Infrarotspektrum des Salzes wurde aufgenommen und kurz besprochen.

On the Formation of Weddellite in Chamaecereus silvestrii, a Cactaceae Species from Northern Argentina

Abstract: Abstract The isolation of well formed crystals of the biomineral weddellite (calcium oxalate dihydrate) from Chamaecereus silvestrii, a Cactaceae species found in the northern part of Argentina, is described. Infrared spectroscopic measurements allow an unambiguous characterization of the nature of the crystals. This is the first report of the presence of a biomineral in this plant species.

The chemistry and biochemistry of vanadium and the biological activities exerted by vanadium compounds.

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

The perovskite structure—a review of its role in ceramic science and technology

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...

CALCIUM OXALATE IN PLANTS: Formation and Function

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.

Molecular mechanism mediating proliferation, defferentiation interralationships during progressie development of the osteoblast phenotype

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...

Application of Spectroscopic Methods for Structural Analysis of Chitin and Chitosan

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.