Home About us Contact
|
Home About us Contact | ||
|
|
||
Additional Bands (additional + bands)
Selected AbstractsA Raman spectroscopic study of the uranyl selenite mineral haynesiteJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2006Ray L. Frost Abstract The mineral haynesite, a uranyl selenite, has been characterised by Raman spectroscopy at 298 and 77 K. Two bands at 811.5 and 800.2 cm,1 are assigned to the symmetric stretching modes of the (UO2)2+ and (SeO3)2, units respectively. These values give calculated UO bond lengths of 1.799 and/or 1.801 Å. The broad band at 861.8 cm,1 is assigned to the ,3 antisymmetric stretching mode of the (UO2)2+ (calculated UO bond length 1.813 Å). Additional bands are observed in the 77 K spectrum. In the spectroscopy of selenite compounds, the position of the antisymmetric stretching vibration occurs at lower wavenumbers than the symmetric stretching mode and thus the band at 740.5 cm,1 is attributed to the ,3 antisymmetric stretching vibration of the (SeO3)2, units. The ,4 and the ,2 vibrational modes of the (SeO3)2, units are observed at 418.5 and 472.1 cm,1. Bands observed at 278.3, 257.3 and 218.8 cm,1 are assigned to OUO bending vibrations. Copyright © 2006 John Wiley & Sons, Ltd. [source] Comprehensive analysis of 112 melanocytic skin lesions demonstrates microsatellite instability in melanomas and dysplastic nevi, but not in benign neviJOURNAL OF CUTANEOUS PATHOLOGY, Issue 7 2001Mahmoud R. Hussein Introduction: Alterations in the length of DNA repetitive sequences (microsatellite instability (MSI)) represent distinct tumorigenic pathways associated with several familial and sporadic tumors. Material and methods: To investigate the prevalence and frequency of MSI in melanocytic lesions, the polymerase chain reaction (PCR)-based microsatellite assay was used to examine formalin-fixed, paraffin-embedded tissues of 30 benign melanocytic nevi, 60 melanocytic dysplastic nevi (MDN), and 22 primary vertical growth phase cutaneous malignant melanomas (CMM). Twenty-four microsatellite markers at the 1p, 2p, 3p, 4q and 9p chromosomal regions were used. Results: MSI was found at 1p and 9p in MDN and CMM but not in benign melanocytic nevi. The overall prevalence of MSI was17/60 (28%) in MDN and 7/22 (31%) in CMM. The frequency of MSI ranged from 2/24 (9%) to 4/24 (17%) and was most commonly found at D9S162. There was a statistically significant correlation between degree of atypia and frequency of MSI (p<0.001) in MDN. There were two MSI banding patterns: band shifts and additional bands. Conclusions: The data presented revealed the presence of low-frequency MSI (MSI-L) at the 1p and 9p regions in both MDN and CMM. Whether the MSI-L pattern reflects a defect in mismatch repair genes is still to be determined. [source] Raman spectroscopy of descloizite and mottramite at 298 and 77 KJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2001Ray L. Frost The Raman spectra of the isomorphous series descloizite [PbZn(VO4)(OH)] and mottramite [PbCu(VO4) (OH)] were obtained at 298 and 77 K. The Raman band at 844 cm,1, assigned to the ,1 symmetric (VO4,) stretching mode for descloizite, is shifted to 814 cm,1 for mottramite. The ,3 mode of descloizite is observed as a single band at 777 cm,1 but this mode is more complex for mottramite with three bands observed in the 77 K spectrum at 811, 785 and 767 cm,1. The bending mode (,2) is observed at 437 cm,1 for descloizite and at 426 cm,1 for mottramite. The ,3 region is complex for both minerals and this is attributed to symmetry reduction of the vanadate unit from Td to Cs. Collecting Raman spectra at 77 K allowed better band separation with observation of additional bands ascribed to the removal of degeneracy. Copyright © 2001 John Wiley & Sons, Ltd. [source] 31P CP/MAS NMR of polycrystalline and immobilized phosphines and catalysts with fast sample spinningMAGNETIC RESONANCE IN CHEMISTRY, Issue 6 2003S. Reinhard Abstract Cross-polarization (CP) at fast magic angle spinning (MAS) frequencies leads to a splitting of the Hartmann,Hahn (HH) matching profile into a centerband and additional bands of higher orders. The matching profiles differ with the substance categories. Therefore, signal intensity is usually lost, when e.g. the routine standard NH4H2PO4 is used for optimizing the 1H,31P HH match prior to measuring phosphines and their metal complexes in polycrystalline or immobilized form. Here, a variety of model compounds, such as Ph2PCH2CH2PPh2 and (CO)2Ni(PPh3)2, which can be used as 31P CP standards for analogous substances or materials are presented. Investigating the influences of MAS frequency, contact time, 1H pulse power and sample volume on the matching profiles of the model compounds leads to general trends. Thereby, a new strategy for measuring difficult samples with CP at high MAS rates has been developed: their optimum CP parameters are derived from the most intense maxima in the HH matching profiles of the corresponding model compounds. This new strategy is compared with variations of a conventional ramp sequence. Although the latter generally provide smaller signal half-widths, the new strategy leads to higher signal intensities. The new method was successfully applied to polycrystalline and immobilized phosphines and catalysts. Copyright © 2003 John Wiley & Sons, Ltd. [source] Genetic differences in omega-gliadins involved in two different immediate food hypersensitivities to wheatALLERGY, Issue 8 2007M. Laurière Background:, Anti-gliadin IgE are expressed in patients with food allergy associated to skin immediate hypersensitivity to hydrolyzed wheat proteins (IHHWP). It is not known if they react with ,5-gliadins, the major allergens in wheat dependant exercise-induced food anaphylaxis (WDEIA), encoded on wheat chromosomes 1B. Methods:, Unmodified gliadins from 14 wheat varieties expressing most of the 1B ,-gliadin alleles, were immunoprobed after SDS-PAGE and blotting, with four sera from patients with IHHWP, and two with WDEIA. Gliadins reacting with IgE were visualized using chemiluminescence and identified according to their mobility and typical SDS-PAGE pattern. The resulting signal was also measured to compare their IgE reactivity. Results:, IHHWP and WDEIA sera exhibited distinct patterns of reactivity. IgE of patients with IHHWP reacted mainly with all ,-gliadins alleles and one ,-gliadin encoded respectively on chromosomes 1D and 1B, but not with any ,5-gliadins alleles as for WDEIA. A few other reactive alleles of ,-gliadins were encoded on chromosomes 1A. Unassigned additional bands of the whole gliadin pattern were also reactive. The four patients with IHHWP exhibited almost the same pattern of reactivity. Main differences concerned band reactivity which modulated the overall reactivity of each wheat variety. Conclusions:, The IgE epitopes involved in IHHWP and WDEIA are different. This suggests that the protein state and the route of exposure to very similar gluten structures, probably orientate the pattern of epitope reactivity and the wheat food allergy manifestations. [source] Formation of complex defects in MncMg1,cO and NicMg1,cO single solid solutionPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2005V. Skvortsova Abstract The results of investigation of the fast neutron irradiation and thermal treatment on absorption spectra of single solid solution of MncMg1,cO, NicMg1,cO and MgO crystals are presented. It is shown that at impurity ion concentration larger than 0.1 mass.% a probability of formation of aggregate centers consisting of more than three F+ - or F-centers is small. After thermal treatment of MncMg1,cO and NicMg1,cO single solid solution irradiated by fast neutrons additional wide bands are observed. We assume that these additional bands belong to complex centers of Mn3+ -VMg and Ni3+ -VMg. The mechanisms of bands formation are discussed. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Structural Identification of Spectroscopic Substates in NeuroglobinCHEMPHYSCHEM, Issue 1 2010Karin Nienhaus Dr. Abstract The structural origins of infrared absorptions of photodissociated CO in murine neuroglobin (Ngb) are determined by combining Fourier transform infrared (FTIR) spectroscopy and molecular dynamics (MD) simulations. Such an approach allows to identify and characterize both the different conformations of the Ngb active site and the transient ligand docking sites. To capture the influence of the protein environment on the spectroscopy and dynamics, experiments and simulations are carried out for the wild type protein and its F28L and F28W mutants. It is found that a voluminous side chain at position 28 divides site B into two subsites, B' and B". At low temperatures, CO in wt Ngb only migrates to site B' from where it can rebind, and B" is not populated. The spectra of CO in site B' for wt Ngb from simulations and experiments are very similar in spectral shift and shape. They both show doublets, red-shifted with respect to gas-phase CO and split by,8 cm,1. The FTIR spectra of the F28L mutant show additional bands which are also found in the simulations and can be attributed to CO located in substate B". The different bands are mainly related to different orientations of the His64 side chain with respect to the CO ligand. Large red-shifts arise from strong interactions between the HistidineNH and the CO oxygen. After dissociation from the heme iron, the CO ligand visits multiple docking sites. The locations of the primary docking site B and a secondary site C, which corresponds to the Mb Xe4 cavity, could be identified unambiguously. Finally, by comparing experiment and simulations it is also possible to identify protonation of its , position (His,64 NgbCO) as the preferred heme-bound conformation in the wild type protein with a signal at 1935 cm,1. [source] | |||||||||||||