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Fourier Transform Raman Spectroscopy (fourier + transform_raman_spectroscopy)
Selected AbstractsUnexpected fluorescence emission of poly(,,,- L -malic acid) in aqueous mediumJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Yaofeng Fan Abstract Unexpected fluorescence of poly(,,,- L -malic acid) (,,,-PMA) without traditional fluorophore was observed firstly. This fluorescent polymer was synthesized via melt polycondensation of L -malic acid. The polymer was characterized by gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermogravimetry (TG), Fourier transform infrared spectroscopy (IR), Fourier transform Raman spectroscopy (Raman), and X-ray powder diffractometry (XRD). The high molecular weight ,,,-PMA was synthesized by the optimum polycondensation at 130°C for 15 h, followed by fractional precipitation with diethyl ether and petroleum ether. The degree of branching of ,,,-PMA was from 10% to 20% according to the reaction condition. Terminal group of ,,,-PMA was mainly hydroxycarboxylic group companied with a few CHCHCOOH groups owing to dehydration of a normal terminal during the melt polycondensation. A fluorescence emission maximum of ,,,-PMA in water appeared at 420 nm when it was excited at 340 nm. Further study indicated that the fluorescence intensity was concentration-dependent, pH-dependent, and molecular-weight-dependent. The fluorescence formation may result from multichain aggregations, which was formed readily in aqueous solution due to intermolecular hydrogen bonds between branched ,,,-PMA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Fourier transform Raman spectroscopy of drugs: quantitative analysis of 1-phenyl-2,3-dimethyl-5-pyrazolone-4-methylaminomethane sodium sulfonate: (dipyrone)JOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2003Antônio O. Izolani Abstract Several drugs provided by the pharmaceutical industry and containing dipyrone as the active principle have different mass percentages of the letter. We describe a procedure for the quantitative analysis of several tablets containing dipyrone (or other solid active principles). The results of Fourier transform Raman band analysis (band area and band height) agree well with the stated contents of dipyrone in the tablets. Copyright © 2003 John Wiley & Sons, Ltd. [source] H2O2 -mediated oxidation of tetrahydrobiopterin: Fourier transform Raman investigations provide mechanistic implications for the enzymatic utilization and recycling of this essential cofactorJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2002Jeremy Moore The oxidation of (6R)- L - erythro -5,6,7,8-tetrahydrobiopterin (6BH4) by H2O2 was examined by Fourier transform Raman spectroscopy. Initial investigations indicated that oxidation proceeds by incorporation of the H2O2 into the 6BH4 molecule without the formation of any additional water. In addition, the pyrimidine ring is affected with the shift of the double bond from the N1,C2 to the C2,N3 position. Such rearrangements of this double bond are observed after the production of either a carbinolamine or quinonoid species. Using deuterium exchange experiments, it was possible to substantiate that the oxidation of 6BH4 initially proceeds by the formation of a 4a-OH-carbinolamine intermediate prior to its spontaneous dehydration yielding the quinonoid dihydro species (qBH2). Furthermore, the hydrogen on the hydroxyl group of the carbinolamine interacts with the oxygen of the carbonyl group at the C4 position of the pyrimidine ring. It is proposed that this interaction facilitates the dehydration of the carbinolamine, thus explaining its instability. Furthermore, a mechanism for the dehydration reaction is suggested, wherein the 4a-hydroxyl group forms an H-bond to the carbonyl group, thus making the oxygen of the hydroxyl group more susceptible to attack by the proton at position N5 of the pyrazine ring, resulting in qBH2 production concomitant with the loss of a water molecule. Upon increasing the concentration of H2O2 the qBH2 converts to 7,8-BH2, which is further oxidized to L -biopterin. Taken together, our results do not support an earlier proposed mechanism implicating a hydroperoxide intermediate in this oxidation reaction. Copyright © 2002 John Wiley & Sons, Ltd. [source] In vitro and in vivo identification of ,pseudocatalase' activity in Dead Sea water using Fourier transform Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 7 2002Karin U. Schallreuter Balneotherapy with Dead Sea water has been reported as a successful treatment modality for psoriasis, atopic eczema and vitiligo, but the precise mode of action has escaped definition so far. The saturating salt concentration (346 g/litre) together with the unique UV spectrum have been suggested to trigger the release of pro-inflammatory and chemotactic mediators. The results of our study show for the first time a high content of transition metal ions (manganese, iron and copper) in Dead Sea water. Using in vitro Fourier transform (FT) Raman spectroscopy, we were able to identify ,pseudocatalase' activity by observing the decomposition of hydrogen peroxide (H2O2) over time by Dead Sea water. Since patients with vitiligo accumulate millimolar levels of H2O2 in their skin, we followed the degradation of H2O2in vivo again utilizing the same technique. The results of this in vitro and in vivo study show for the first time a ,pseudocatalase' activity of Dead Sea water and provide evidence that the antioxidant properties of Dead Sea water bathing could play an important role in this unique treatment modality. Furthermore, the use of non-invasive in vivo FT-Raman spectroscopy introduces an excellent biomedical application in investigative dermatology. Copyright © 2002 John Wiley & Sons, Ltd. [source] Noninvasive characterization of human stratum corneum of undiseased skin of patients with atopic dermatitis and psoriasis as studied by Fourier transform Raman spectroscopyBIOPOLYMERS, Issue 3 2001Johannes Wohlrab Abstract Etiopathogenetic regulatory disorders of epidermal metabolism and the subsequent changes in the molecular pattern of the stratum corneum play an important role in the clinical differentiation of particular dermatoses (e.g., psoriasis, atopic dermatitis). In this study we present in vitro Fourier transform Raman spectra of the stratum corneum from healthy skin, as well as from clinically undiseased skin of the right heel of atopic and psoriatic volunteers. Differences in the averaged spectra were detected, particularly in the spectral ranges of 1112,1142 (lipid band), 1185,1220, and 1394,1429 cm,1. By using the first derivative of the averaged spectra and/or a statistical evaluation of the spectroscopic data it was possible to distinguish the skin types examined. © 2001 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 62: 141,146, 2001 [source] | ||||||||||