Preparation and properties of lanthanum tungstate and studies of its ion-exchange and electrochemical behaviour

A new inorganic ion-exchanger lanthanum tungstate has been prepared by mixing lanthanum nitrate and sodium tungstate. The refluxed product has been found to be most suitable; therefore, most of the electrochemical and ion-exchange studies were performed on this product. The material is a weak cation exchanger with a capacity of 0.80 mmol per gram. Electrochemical studies are performed by preparing a pellet of this exchanger in polystyrene; charge density and membrane potential have been calculated. The results are discussed.     

Alkaloids ofNitraria komarovii. VI. Structure and synthesis of isokomarovine and of komarovidinine

Two new alkaloids, isokomarovine and komarovidinine, have been isolated from the epigeal part of the plantNitraria komarovii Iljin et Lava. The passage from isokomarovine to komarovidinine has been performed. Their structures have been established on the basis of spectra and experimental facts: 1-(quinolin-5′-yl)-9H-pyrido[3,4-b]indole and indolo[3,2,1-de]quinolino[4,5-gh][1,5]naphthyridine, respectively. Their synthesis has been performed.     

Synthesis and characterization of sodium-tetramethylammonium decamolybdate

Sodium-tetramethylammonium decamolybdate in acidified solution has been crystallized. Chemical analysis, thermogravimetric and X-ray studies have been performed.     

Experimental and theoretical investigations of benzamide oxime

The FT-IR (4000-400 cm(-1)) and FT-Raman (4000-100 cm(-1)) spectral measurements of benzamide oxime and complete assignments of the observed spectra have been proposed. Ab initio and DFT calculations have been performed giving energies, optimized structures, harmonic vibrational frequencies, depolarization ratios, IR intensities, Raman activities and atomic displacements. Furthermore, force field calculations have been performed by normal coordinate analysis. Force field calculations showed that several normal modes are mixed in terms of the internal coordinates. A complete assignment of the observed spectra, based on spectral correlations, electronic structure calculations and normal coordinate analysis, has been provided.     

Polarity and Structure of Se-Esters of Diselenophosphinic Acids: Experimental and Theoretical Conformational Analysis in Solution

Russian Journal of General Chemistry - Conformational analysis of Se-esters of diselenophosphinic acids has been performed and their polarities have been determined using the methods of dipole...     

Non-invasive Analysis of Artistic Heritage and Archaeological Findings by Time Resolved IR Thermography

The structure and the preservation state of artistic heritage and archaeological findings have been studied by the analysis of the heat diffusion process in the sample. The investigations have been performed by non-invasive time resolved infrared thermography(IRT). Thickness maps, buried defects detection, inhomogeneity and corrosion analysis, as well as the quality check of welding and reinforcements elements, have been performed on the studied samples. This revised version was published online in July 2006 with corrections to the Cover Date.     

Complementary DSC and dilatometric investigation of M-PTFE pyrotechnic compositions

Results of high thermal resolution microcalorimetric and dilatometric measurements performed on reducer — polytetrafluoroethylene (M-PTFE) pyrotechnic compositions have been discussed. The materials were selected for the study because of their behaviour in combustion tests. Two complementary thermal properties, i.e. the specific heat and coefficient of linear thermal expansion (CLTE), have been analysed in detail. The specific heat was obtained from DSC measurements performed from −20 to 375°C. Measurements of CLTE and linear expansion were carried out from −40 to 270°C. In both cases the measurements were performed on thermocycling with the high thermal resolution preserved. A special attention has been paid to a two-stage phase transition occurring just below the room temperature. This revised version was published online in July 2006 with corrections to the Cover Date.     

Structural study of pyrimidine nucleoside analogues. I: Molecular mechanics and semiempirical calculations of 2′-deoxy-2′-fluoroarabinofuranosyluracils

Molecular mechanics (MM) calculations have been performed on the title compounds. For the MM minimum energy conformation obtained by conformational analysis, molecular orbital (MO) calculations (MNDO and AM1) have also been performed. The geometries obtained have been compared with the experimental ones extracted from the Cambridge Structural Database (CSD). A qualitative structure-activity relationship has been pointed out based on the electrostatic potentials calculated at different positions on the electronic surface.     

Chemisorption of Glycidyl Spacer on Magnetic Nanoparticles and Immobilization of Albumin and Quinacrine

Chemisorption of a glycidyl spacer on the surface of magnetic nanoparticles from three solvents has been performed. It has been shown that the chemisorption from benzene is the most efficient. Human albumin and quinacrine as a model pharmaceutical have been immobilized via a glycidyl spacer. A mechanism of the interaction of albumin and quinacrine with glycidyl groups has been suggested.     

Thermal decomposition of meat and bone meal

A series of runs has been performed to study the thermal behavior of meat and bone meal (MBM) both in inert and reactive atmosphere. Although they are actually burned, the thermal decomposition of such MBM wastes has not been studied from a scientific point of view until now. The aim of this work is to present and discuss the thermogravimetric behavior of MBM both in nitrogen and air atmospheres. A thermobalance has been used to carry out the study at three different heating rates. A kinetic scheme able to correlate simultaneously (with no variation of the kinetic constants) the runs performed at different heating rates and different atmospheres of reaction is presented.     

The regio- and stereoselective oxyamination of pinenes and camphene

The osmium-induced vicinal oxyaminations of pinenes and camphene have been performed with high regio- and stereoselectivities.     

Theoretical and experimental studies on solubility and reactivity behavior of lysergol,elymoclavine, and dihydrolysergol

Lysergol, elymoclavine (Δ^9,10 and Δ^8,9 regioisomers), and dihydrolysergol are important members of ergolines. The present work reports their comparative study in gas and solvent phase (water) that has been performed both experimentally and theoretically. Theortical calculations have been carried within the density functional theory formalism to analyze the structural and electronic properties of these molecules with B3LYP hybrid exchange–correlational fuctional in conjunction with 6‐311++G (d,p) basis set. Hessian calculations are performed at B3LYP/6‐31G (d,p) level of theory in gas phase as well as other solvent phases. Solvent phase calculations are performed using Onsager reaction field model as implemented in Gaussian 03. A good agreement has been found between experimental and theoretical infrared and nuclear magnetic resonance (NMR) spectra. The calculated NMR data has been analyzed statistically. Stability of these regioisomers has been analyzed in terms of the energy gap between highest occupied molecular orbital and lowest unoccupied molecular orbital (HOMO–LUMO gap). Calculations for lysergol and elymoclavine in water as solvent were carried to examine the effect of solvent on the HOMO–LUMO levels and energy of these molecules. © 2012 Wiley Periodicals, Inc.     

Synthesis,structure, and biological evaluation of novel N- and O-linked diinositols

Several O-and N-linked inositols and/or aminoinositols have been prepared by iterative opening of epoxides and aziridines derived from homochiral cyclohexadiene cis-diols. The three inositols and their intermediate conduritols (conduramines) were tested against several glycosidases (alpha- and beta-glucosidase, alpha- and beta-galactosidase, alpha- and beta-mannosidase) in an assay that measured the rate of hydrolysis of p-nitrophenolglycosides rather than the concentration of p-nitrophenolate. Somewhat surprisingly, the best inhibition was seen against beta-galactosidase with several of the compounds. The inositols linked through oxygen or nitrogen were subjected to calcium binding studies performed in NMR experiments. Detailed analysis of the title compounds by NMR spectroscopy has been performed, and full assignments were made. One of the attendant benefits of the preparation of these compounds has been expressed in the design and synthesis of new salen catalysts whose effectiveness has been compared with Jacobsen's catalyst in the epoxidation of styrene.     

Many-body perturbation theory and polarization propagator studies of the structure, energetics and excitation spectrum of CO3

Geometry optimization has been performed on CO₃ in the SCF approximation and in the second-, third-, and fourth-order MBPT approximations limited to single and double substitutions using a double-zeta plus polarization basis set. The energetics of the formation and decomposition of CO₃ from the reactions CO₂ + O(¹D) → CO₃ and CO₃ + CO → 2CO₂, respectively, have been calculated in several approximations including full fourth-order MBPT. In addition first-order polarization propagator calculations have been performed to identify the low-lying excited states.     

Partial filling micellar electrokinetic chromatography optimization studies of ibuprofen, codeine and degradation products, and coupling to mass spectrometry

Studies have been performed to evaluate whether an on-line partial filling-micellar electrokinetic chromatography (PF-MEKC) system could be applied to a recently developed MEKC method for the separation of ibuprofen, codeine and one of the degradation products. Attempts to couple the PF-MEKC system to MS have also been performed. SDS concentration, micellar zone length and concentration of acetonitrile in the buffer were optimized using factorial design. When a small micelle zone was injected directly after the sample introduction, the results improved markedly. The MS parameters have not been optimized, but the studies show promising results for the use of PF-MEKC-mass spectrometry for identification of the degradation products.     

Preparation and characterization of new hydrogels based on hyaluronic acid and α,β-polyaspartylhydrazide

Hyaluronic acid (HA) has been crosslinked with α,β-polyaspartylhydrazide (PAHy). The crosslinking reaction has been performed in acidic medium in the presence of various amounts of N-ethyl-N′-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC). All obtained samples have been characterized by FT-IR analysis and swelling measurements in double distilled water that have confirmed the occurrence of a chemical linkage between two polymers and the affinity towards aqueous medium of HA-PAHy networks, respectively.In vitro degradation assays have been performed in simulated physiological conditions as well as in the presence of hyaluronidase. Experimental data evidenced that HA-PAHy samples undergo a poor chemical and a reduced enzymatic degradation unlike native HA.     

Modification of Diphenylphosphorylacetic Hydrazide with Thiosemicarbazide and Triazole Units

Thiosemicarbazides of diphenylphosphorylacetic acid and their cyclic derivatives have been synthesized. Functionalization of the obtained 1,2,4-triazole-3-thiones with ethyl 2-bromoacetate at the sulfur atom has been carried out, the obtained esters have been transformed into the corresponding hydrazides via hydrazinolysis. Preliminary pharmacological tests of the synthesized compounds have been performed.     

Vibrational spectra and normal mode analysis of aceheptylene and 3,5,8,10-tetramethylaceheptylene

The infrared and Raman spectra of aceheptylene and 3,5,8,10-tetramethylaceheptylene have been recorded, and the normal mode analyses have been performed with a force field which has been modified for nonbenzenoid aromatic molecules. On this basis, the fundamental frequencies have been assigned. Comparison of the vibrational spectra for the two molecules has served as an internal method of making assignments. The agreement between calculated and observed values for both molecules is satisfactory.     

Molecular orbital calculations of the chemisorption and diffusion of oxygen and water on a graphite substrate

Semi-empirical molecular orbital calculations have been performed using the macro-molecular orbital model to simulate the chemisorption and diffusion of oxygen and water on a graphite substrate. By comparing with previous calculations of this type we have shown that the method adopted for minimising edge effects by saturating dangling carbon bonds reproduces the surface properties adequately for our purposes. Calculations using model substrates of 16 carbon and 10 hydrogen atoms and 24 carbon and 12 hydrogen atoms have been performed.The chemisorption and diffusion of oxygen has been studied by means of an equipotential contour map and the diffusion path and activation energy found. Less extensive calculations on water on graphite allow us to give a most probable diffusion path and activation energy. Sufficient results have been obtained to allow some qualitative remarks to be made on the inhibition of oxidation by an H₂O mechanism.     

FTIR and Ab Initio Studies of Diisopropylsulfoxide and its Solutions

Fourier transform infrared (FTIR) measurements, ab initio quantum chemical calculations at the restricted Hartree–Fock (RHF) level and density functional theory (DFT) calculations have been performed to study molecular interactions in pure diisopropylsulfoxide (DiPSO) and the binary mixtures DiPSO/CCl₄ and DiPSO/water. The optimized molecular geometry, vibrational wavenumbers, dipole moments and several thermodynamic parameters of free DiPSO and DiPSO/water 1:1 complex in the ground state were calculated using the RHF and B3LYP methods with the 6-31G(d) basis set. A fitting procedure has been performed for both SO and CH stretching regions and a detailed spectral interpretation has been done based on the data obtained from ab initio calculations, infrared spectra and band deconvolution analysis.