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Infrared Data (infrared + data)
Selected AbstractsRaman and infrared studies of synthetic Maya pigments as a function of heating time and dye concentrationJOURNAL OF RAMAN SPECTROSCOPY, Issue 9 2007F. S. Manciu Abstract Maya Blue is a famous indigo-based pigment produced by the ancient Mayas. The organic/inorganic complexes inspired by Maya Blue have led to a new class of surface compounds that have novel applications to pigment industries. Materials analyzed in the present work are made by a synthetic route, and demonstrate chemical stability similar to that of the ancient Maya Blue samples. However, we have learned that stable complexes can be synthesized at much higher dye concentrations than used by the Mayas. Analysis by FT-Raman and FT-IR spectroscopy demonstrates the partial elimination of the selection rules for the centrosymmetric indigo, indicating distortion of the molecule. This distortion accounts for the observed color changes, as the molecular orbital structure is modified, allowing the complex to stabilize. The spectroscopic data also shows the disappearance of the indigo NH bonding, as the organic molecules incorporate into palygorskite material. A structural change of indigo to dehydroindigo during heating is suggested by this result. Infrared data confirm the loss of zeolitic water and a partial removal of structural water after the heating process. Evidence of bonding between cationic aluminum and dehydroindigo through oxygen and nitrogen is revealed by FT-Raman measurements at higher dye concentrations. Copyright © 2007 John Wiley & Sons, Ltd. [source] The Heteropolytungstate Core {BW13O46}11, Derived as Monomer, Dimer, and TrimerCHEMISTRY - A EUROPEAN JOURNAL, Issue 25 2007Nathalie Leclerc-Laronze Dr. Abstract A study of the borotungstate system has led to the characterization of new, original compounds based on the unconventional Keggin derivative [H3BW13O46]8, ion (denoted as 1). [H3BW14O48]6, (2) and the dimer [H6B2W26O90]12, (3) crystallize as mixed cesium/ammonium salts and have been characterized by single-crystal X-ray diffraction analysis. Anion 2 reveals an unusual arrangement, consisting of an outer {W3O9} core grafted onto the monovacant [BW11O39]9, Keggin moiety and exhibits an unprecedented distorted square-pyramidal arrangement for a cis -{WO2} core. Elemental analysis, supported by bond distance analysis, is consistent with the presence of three protons distributed over the terminal oxygens of the outer {W3O7} capping fragment. The [H6B2W26O90]12, ion (3) is formally derived from the direct condensation of two [H3BW13O46]8, subunits. The cisoid arrangement of the two [BW11O39]9, subunits, coupled with the antiparallel arrangement of the two quasi-linear OW,,,OWOH2 chains within the central {W4O12} connecting group, breaks any symmetry, thereby resulting in a chiral compound. Polarography and pH-metric titrations reveal the formation of the monomeric precursor [H3BW13O46]8, (anion 1) under stoichiometric conditions. 183W NMR analysis of 2 and 3 in solution gives complex spectra, consistent with the presence of equilibria between several species. In the frame of this study, we also report on a structural re-investigation of the [H6B3W39O132]15, ion (4) based on reliable results obtained in the solid state by means of single-crystal X-ray diffraction analysis, and in solution by means of 1D and 2D COSY 183W NMR. X-ray diffraction analysis revealed the presence of three attached aquo ligands on the central {W6O15} connecting core, generating three OW,,,OWOH2 quasi-linear chains, which are responsible for the chirality of the trimeric assembly. This structural arrangement accounts for the 39-line 183W solution spectrum. The 2D COSY spectrum permits reliable assignments of the six strongly shielded resonances (around ,250 and ,400,ppm) to the six central W atoms, as well as additional assignments. The origin of such strong shielding for these particular W atoms is discussed on the basis of previously published results. Infrared data for compounds 1, 3, and 4 are also presented. [source] Preparation and thermomechanical properties of epoxy resins modified by octafunctional cubic silsesquioxane epoxidesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 14 2004Khine Yi Mya Abstract The thermomechanical properties of octafunctional cubic silsesquioxane-modified epoxy resins associated with dicycloaliphatic hardener (4,4,-dimethyldiaminodicyclo hexyl methane) were studied using thermogravimetric analysis, differential scanning calorimetry, and dynamic mechanical analysis. The structures of epoxy resin containing cubic silsesquioxane epoxides were characterized by Fourier transform infrared spectroscopy and wide-angle X-ray scattering techniques. In this work, octa(dimethylsiloxybutylepoxide) octasilsesquioxane (OB), and octa(glycidyldimethyl-siloxyepoxide) octasilsesquioxane (OG), were synthesized and used as additives to improve the properties of a commercial epoxy resin by exploring the effects of varying the ratio of OB or OG. The commercial Ciba epoxy resin (Araldite LY5210/HY2954) was used as a standard. It was found, by thermogravimetric analysis and dynamic mechanical analysis, that the highest thermal stability was observed at N = 0.5 (N = number of amine groups/number of epoxy rings). No glass transition temperature was observed by adding 20 mol % OB to the Ciba epoxy resin, indicating the reduction of chain motion in the presence of octafunctional cubic silsesquioxane epoxide. The storage modulus of the OB-modified epoxy resin also increased, especially at higher temperatures, compared with the Ciba epoxy resin under identical curing conditions. Fourier transform infrared data elucidated the preservation of cubic silsesquioxane structure after curing at high temperature. In contrast, the OG/Araldite LY5210/HY2954 systems gave poorer thermomechanical properties. The low viscosity of OB at room temperature (, 350 cPs) makes it suitable for composite processing and, when used in conjunction with the Ciba epoxy, lowers the viscosity of this system as well. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3490,3503, 2004 [source] Vibrational spectroscopic study of budesonideJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2007H. R. H. Ali Abstract The Raman spectrum of budesonide is reported for the first time, and molecular assignments are proposed on the basis of ab initio BLYP DFT calculations with a 6-31 G* basis set and vibrational wavenumbers predicted on a quasi-harmonic approximation. Comparison with previously published infrared data has explained several spectral features, and the relative band intensities in the CO and CC stretching regions are interpreted. The results from this study provide data that can be used for the preparative process monitoring of budesonide, an important steroidal pharmaceutical in various dosage forms, and its interaction with excipients and other components. Copyright © 2007 John Wiley & Sons, Ltd. [source] A method of identifying and locating sea-breeze fronts in north-eastern Brazil by remote sensingMETEOROLOGICAL APPLICATIONS, Issue 3 2006O. Planchon Abstract A method of identifying sea-breeze fronts by remote sensing (visible and infrared data from the GOES-8 satellite) was applied to north-eastern Brazil. The aim of the study was to estimate the frequency of observed sea-breeze fronts and the average distance they penetrate inland at 1800 UTC. During the dry season (between September and December) in 2000, the highest frequency of sea-breeze fronts was recorded on the northern fringe of the study area. The sea-breeze fronts penetrated furthest inland between September and November, with a maximum distance from the coast at Ceará of 100 km. Copyright © 2006 John Wiley & Sons, Ltd. [source] A high-resolution radio survey of Class I protostarsMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2000P. W. Lucas We report the results of a survey of low-mass Class I protostars in the cm continuum. In the initial survey, seven sources in the Taurus star formation region were observed with the VLA at 0.25-arcsec resolution. All seven sources drive CO outflows and display Herbig,Haro flows in the optical or near-infrared (NIR) wavebands. Four out of seven sources were detected, two of which are new discoveries in systems of very low luminosity, one being the lowest luminosity system detected to date in the cm continuum. Notably, three sources were not detected to a 3, limit of 0.10 mJy/beam, which indicates that significant cm continuum emission is not a universal feature of Class I systems with outflow activity. Subsequent observations of HH30, a more evolved Class II system, found no emission to a 3, limit of 0.03 mJy/beam. After comparison with near infrared data, we suggest that the discriminating feature of the detected systems is a relatively high ionization fraction in the stellar wind. Temporal variability of the outflow may also play a role: only recently ejected knots may have sufficiently dense plasma to be optically thick to free,free emission, and hence produce detectable flux. The one relatively bright source, IRAS 04016+2610 (L1489 IRS), is clearly resolved on a 0.4-arcsec scale at 2 and 3.5 cm. Additional imaging with MERLIN did not detect this source with a 0.04-arcsec beam, indicating that the radio emission is generated in a region with a radius of ,25 au, which is broadly similar to the radius of the bipolar cavities inferred from models of NIR data. Interpretation of this system is complicated by the existence of a quadrupolar outflow, i.e. two bipolar outflows along roughly perpendicular axes, which we originally detected through polarimetric imaging. We present an NIR H2 image in which a bow shock in the secondary outflow is clearly seen. This complicated structure may have been caused by a gravitational interaction between two protostars. [source] New absolute magnitude calibrations for WUrsa Majoris type binariesASTRONOMISCHE NACHRICHTEN, Issue 1 2009Z. Eker Abstract Parallaxes of W UMa stars in the Hipparcos catalogue have been analyzed. 31 W UMa stars, which have the most accurate parallaxes (,, /, < 0.15) which are neither associated with a photometric tertiary nor with evidence of a visual companion, were selected for re-calibrating the Period-Luminosity-Color (PLC) relation of W UMa stars. Using the Lutz-Kelker (LK) bias corrected (most probable) parallaxes, periods (0.26 < P < 0.87, P in days), and colors (0.04 < (B , V)0 < 1.28) of the 31 selected W UMa, the PLC relation have been revised and re-calibrated. The difference between the old (revised but not bias corrected) and the new (LK bias corrected) relations are almost negligible in predicting the distances of W UMa stars up to about 100 pc. But, it increases and may become intolerable as distances of stars increase. Additionally, using (J , H)0 and (H , Ks)0 colors from 2MASS (TwoMicron All Sky Survey) data, a PLC relation working with infrared data was derived. It can be used with infrared colors in the range ,0.01 < (J , H)0 < 0.58, and ,0.10 < (H , Ks)0 < 0.18. Despite of the fact that the 2MASS data refer to single epoch observations which are not guaranteed to be taken at maximum brightness of theWUMa stars, the established relation has been found surprisingly consistent and reliable in predicting LK corrected distances of W UMa stars (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||