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.

Übergangsmetallchalkogenverbindungen. Zur Kenntnis von Ba5(ReO6)2 und Ba3(ReO5)2

Abstract: Die IR-Spektren von Ba5(ReO6)2 und Ba3(ReO5)2 werden gemessen und diskutiert. Fur Ba5(ReO6)2 last sich das Vorliegen von ReO6-Gruppen im Gitter wahrscheinlich machen. Weiterhin werden die Elektronenspektren der Salze vermessen und teilweise zugeordnet. Bei den ermittelten Banden handelt es sich um „charge transfer” Ubergange O Re. Die Bindungsverhaltnisse im Perrhenat, Meso- und Orthoperrhenat werden diskutiert. The infrared spectra of Ba5(ReO6)2 and Ba3(ReO5)2 have been measured and discussed. In the case of Ba5(ReO6)2 there are probably isolated ReO anions. The electronic spectra of the salts are reported and assigned. Also the bonding in the perrhenate, mesoperrhenate and orthoperrhenate is discussed.

K2[Os(CN)5NO], ein neuer Komplex des zweiwertigen Osmiums. Vergleichende Untersuchung mit den entsprechenden Fe(II)- und Ru(II)-Verbindungen

Abstract: Die Darstellung und Eigenschaften von K2[Os(CN)5NO] · 2H2O werden beschrieben. Von dieser Verbindung sowie auch von Na2[Fe(CN)5NO] · 2H2O und K2[Ru(CN)5NO] · 2H2O werden die Festkorperelektronen- und die IR-Spektren untersucht und diskutiert. Die Reaktion der drei Komplexe mit Sulfid-Ionen (GMELIN-Reaktion) wird untersucht. The preparation and properties of K2[Os(CN)5NO] · 2H2O are reported. The electronic and vibrational spectra of the compound have been measured and compared with the corresponding compounds of Fe(II) and Ru(II). The reaction of the three complexes with S2− ions investigated.

Vibrational spectra of the layered monofluorophosphate (V), NH4Ag3(PO3F)2

Abstract: The powder Fourier-transform (FT) infrared (IR) and Raman spectra of the recently characterized NH4Ag3(PO3F)2 were recorded and are discussed with a site-symmetry analysis based on its known structural data. Some comparisons are made with the solution spectra of the PO3F2− anion and with those of crystalline Ag2PO3F. Copyright © 2009 John Wiley & Sons, Ltd.

Interaction of the vanadyl (IV) cation with carnosine and related ligands

Abstract: The interaction of the vanadyl (IV) (VO2+) cation with carnosine (the dipeptide beta-alanyl-histidine) has been investigated by electron absorption spectroscopy at high ligand-to-metal ratios and at different pH values. The results show that in the range 6.0-8.5, the cation interacts with the imidazole group of four different carnosine molecules and points to the presence of an axially coordinated water molecule. These suppositions were confirmed by the behavior of the VO2+/imidazole system, which was investigated under similar experimental conditions, and supported by previous ENDOR (electron-nuclear double resonance) results. The study was complemented with additional measurements using the glycylglycine, glycylglycine/imidazole, and histidine systems as ligands.

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.