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.

Structural and IR-Spectroscopic Characterization of Aqua Lithium Acesulfamate, an Outlier of the M(ace), M: Na+, K+, Rb+, Cs+, Isomorphic Series

Abstract: The crystal structure of aqua lithium 6-methyl-1,2,3,-oxathiazine-4(3H)-one, 2.2-dioxide, for short Li(ace)H2O, was determined by X-ray diffraction methods. It crystallizes in the triclinic P $$\overline {1}$$ space group with a = 6.1750(9) A, b = 7.3969(9) A, c = 9.016(1) A, α = 105.88(1)°, β = 94.59(1)°, γ = 97.80(1)°, and Z = 2 molecules per unit cell. The crystal structure of Li(ace)H2O sharply departs from the other heavier alkaline-metal acesulfamates, namely the monoclinic isotypic M-ace (M from Na+ to Cs+) family of salts. Lithium is in a distorted LiO4 tetrahedral coordination with acesulfamate carbonyl, sulfoxide and water oxygen atoms. The FTIR spectrum of the new compound was also recorded and is briefly discussed. Some comparisons with other simple acesulfamate salts are also made. The synthesis of aqua lithium acesulfamate, Li(C4H4NO4S)H2O, and its structural characterization by single-crystal X-ray diffractometry are reported. The FTIR spectrum of the salt is analyzed by comparison with data of related compounds.

Factor Group Analysis of the Ba3 (MnO4)2 Lattice and A Revised Set of Force Constants for the MnO3- 4 Ion

Abstract: An assignment has been proposed for the internal vibrations of the MnO3- 4 ion, obtained from infrared and Raman spectra as well as from i. r. measurements of solid solutions of the type Ba3(PO4)2-x(MnO4)x and based on a factor group analysis of the Ba3(MnO4)2 lattice. A new set of force constants for the anion are also calculated from a modified valence force field.

Das ν1/ν3-Frequenzen-Verhältnis bei tetraedrischen Oxoanionen der Hauptgruppen- elemente und die Schwingungseigenschaften von Xenon-Tetroxid / The ν1/ν3 Frequency Ratio in Tetrahedral Oxoanions of The Main Group Elements and the Vibrational Properties of Xenon-Tetroxid

Abstract: Abstract In an earlier work we have theoretically derived and explained certain rules relating the ν1/v3 frequency ratio of tetrahedral oxoanions of the transition metals with some basic properties of the anions. It is now demonstrated that these rules are also valid for oxoanions of the main group elements of the periodic system. Applying these and other relations it was possible to predict the value of the symmetric stretching frequency ν1(A1) of xenon tetroxide. Some vibrational properties of XeO4 (force constants, mean amplitudes of vibration, the Coriolis coupling constant and the bond order) are also calculated and compared with those of related species.

Spectroscopic behaviour of the two CO stretching vibrations in free and complexed theophylline

Abstract: The behaviour of the stretching vibration of the two CO groups in free theophylline and in some of its metallic complexes of stoichiometry [MII(tp)2(H2O)4] were investigated by means of infrared and Raman spectroscopy. It is demonstrated that after complexation an inversion of the relative band positions of these two stretching modes takes place. This behaviour could be clearly explained on the basis of the structural characteristics of the investigated complexes.

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.