Preparation and characterization of chelating resins loaded with 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol for preconcentration of rare earth elements

 Chelating resins prepared by sorption of 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol (5-BrPADAP) on macroporous resins (Amberlite XAD-4 and XAD-7) were characterized. The adsorption properties (amount of chelating agent adsorbed per gram of resin, sorption kinetics, retention capacity, etc.) and the thermodynamic quantities of each adsorption process were determined. The retention of some rare earth elements (e.g. Er, Yb and Lu) on these chelating resins was studied in order to preconcentrate them for their determination by X-Ray fluorescence spectrometry. Received: 7 September 1995/Revised: 2 January 1996/Accepted: 10 January 1996     

Isomerisation of ω-hydroxyalkenes under hydroxycarbonylation conditions in palladium catalysed aqueous phase systems

The ω-hydroxyolefins 3-buten-1-ol, 3-buten-1-methyl-1-ol and 4-penten-1-ol were subjected to hydroxycarbonylation conditions in water in the presence of PdCl₂(PhCN)₂ and 4-8 equiv. of water soluble tris(3-sodiumsulfonatophenyl)phosphine (TPPTS), or N-bis(N′,N′-diethyl-2-aminoethyl)-4-aminomethylphenyl-diphenylphosphine (N3P). Under conditions of high conversion, the olefins primarily undergo isomerisation through a chain walking mechanism with selectivities for aldehyde ranging from 65% to 98%, with the lower values for longer chain alcohols. The lactones formed as the minor product are almost exclusively branched, indicating that in the first step 2,1-insertion is strongly favoured over 1,2-insertion. In the N3P system also linear lactone is produced at lower conversion. Running the reaction in D₂O produces multiple deuterium incorporation in all positions of the carbon chain. A mechanism is discussed.     

IR-Spektren einiger Doppeloxide des Typs Te3MIVO8

I.R. Spectra of Some Double Oxides of the Type Te₃M^IVO₈ The infrared spectra of the phases Te₃M^IVO₈ (M^IV = Ti, Zr, Hf, Sn), structurally related to fluorite, have been recorded and discussed. It is shown that all the observed have a complex origin, and it is not possible to assign them to definite vibrations of the metal-oxygen polyhedra present in the lattices.     

Polarized infrared and Raman spectra of CsHSeO4 and CsDSeO4 single crystals

The polarized absorption infrared spectra of CsHSeO₄ and CsDSeO₄ single crystals and polarized Raman spectra of the CsHSeO₄ single crystal were measured at room temperature. The polarization features of the internal vibrations of the HSeO⁻₄ ions are predicted on the basis of the X-ray structure assuming strong couping between the vibrations of the two shortest Se---O bonds and an intermediate Se---O bond. The bending methods γOH and δOH of a hydrogen bond appear at 805 cm⁻ and 1258 cm⁻¹, respectively. The νOH absorption has the ABC structure due to Fermi resonance of νOH with the overtones of the δOH and γOH vibrations. A similar shape of the νOH band is observed in the Raman spectra. The νOD absorption has a different shape from that of νOH. Intra-chain coupling was observed for the νOH and νOD vibrations.     

Das Schwingungsspektrum von Magnesium-orthovanadat

The infrared and laser-Raman spectra of crystalline Mg₃(VO₄)₂ are reported and a factor group analysis for the full lattice is presented to support the discussion. The 1,000 to 600 cm^?1 region of the spectrum is essentially related to internal (stretching) modes of the greatly distorted VO₄ tetrahedra, whereas the bands in the low frequency region must be assigned to complex vibrations originating in the interaction of the bending vibrations of the tetrahedral groups with the external modes.     

Vibrational spectra of the adduct of 1,8-bis(dimethylamino)naphthalene with dichloromaleic acid (DMAN x DCM)

The infra-red (IR), Raman (R) and inelastic incoherent neutron scattering (IINS) spectra, particularly in low frequency region, of the title ionic adduct were studied. It is shown that all low frequency vibrations (below 200 cm(-1)) of (CH3)2N groups of protonated 1,8-bis(dimethylamino)naphthalene (DMAN)--clearly observed in IINS spectra--are sensitive to the environment, i.e. to the type of counterion forming short contacts with C-H bonds of methyl groups. The internal frequencies were also calculated by ab initio method. The results are consistent with numerous observations of the counteranion effect on the geometry of the protonated DMAN. The conclusions are compared with structural and NMR studies reported recently for the 1,8-bis(dimethylamino)naphthalene with dichloromaleic acid (DMAN x DCM) adduct. The single crystal R polarized spectra taken over the frequency range 20-3200 cm(-1) were analyzed in detail. We have shown that a substantial difference in the IR spectrum of the dichloromaleic acid (DCM) anion in the DMAN adduct and in the potassium salt results from different geometries of OHO hydrogen bonds. In the case of potassium salt the chains of longer intermolecular hydrogen bonds are formed described by means of a double minimum potential.     

Theory of Nucleon-Nucleon Scattering

We present a new study of kinematical problems of relativistic nucleon-nucleon interactions, more complete than the previous studies. Two-component spinor formalism is used throughout. Several choices of spinor bases, their relations, crossing relations in all channels, helicity amplitudes, partial-wave amplitudes, the absence of kinematical singularities, and unitarity are discussed. The contributions of arbitrary intermediate states J in the unitarity are summed and the Regge forms for all five scalar amplitudes are obtained.     

Impact of the Cooking Process on Metabolite Profiling of Acanthocereus tetragonus,a Plant Traditionally Consumed in Mexico

Acanthocereus tetragonus (L.) Hummelinck is used as an alternative food source in some Mexican communities. It has been shown that the young stems of A. tetragonus provide crude protein, fiber, and essential minerals for humans. In this work, we analyzed the phytochemical profile, the total phenolic content (TPC), and the antioxidant activity of cooked and crude samples of A. tetragonus to assess its functional metabolite contribution to humans. The phytochemical profile was analyzed using Ultra-High-Performance Liquid Chromatography coupled to High-Resolution Mass Spectrometry (UHPLC-PDA-HESI-Orbitrap-MS/MS). Under the proposed conditions, 35 metabolites were separated and tentatively identified. Of the separated metabolites, 16 occurred exclusively in cooked samples, 6 in crude samples, and 9 in both crude and cooked samples. Among the detected compounds, carboxylic acids, such as threonic, citric, and malic acids, phenolic acids, and glycosylated flavonoids (luteolin-O-rutinoside) were detected. The TPC and antioxidant activity were analyzed using the Folin–Ciocalteu method and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical inhibition method, respectively. The TPC and antioxidant activity were significantly reduced in the cooked samples. We found that some metabolites remained intact after the cooking process, suggesting that A. tetragonus represents a source of functional metabolites for people who consume this plant species.     

Surface Analysis of Inhibitor Film Formed by 4-Amino-N-(1,3-thiazol-2-yl) Benzene Sulfonamide on Carbon Steel Surface in Acidic Media

Inhibitive properties of the antibacterial sulfa drug sulfathiazole—IUPAC name being 4-amino-N-(1,3-thiazol-2-yl) benzene sulfonamide—on the corrosion of carbon steel in 1.0 M HCl solution were investigated using weight loss measurements, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). Sulfathiazole is a good adsorption inhibitor, and the inhibition efficiency increases with increasing concentration. Adsorption is spontaneous and is best described by Temkin isotherm. XPS analysis showed, at this stage, that the main product of corrosion is a nonstoichiometric Fe³⁺ oxide/oxyhydroxide consisting of a mixture of Fe₂O₃, α, and γ-FeO(OH) and/or Fe(OH)₃, where α, γ-FeO(OH) is the main phase.