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Spectroscopy Data (spectroscopy + data)
Kinds of Spectroscopy Data Selected AbstractsComparison of fatty acid profiles and mid-infrared spectral data for classification of olive oilsEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 2 2010Gozde Gurdeniz Abstract The composition of olive oils may vary depending on environmental and technological factors. Fatty acid profiles and Fourier-transform infrared (FT-IR) spectroscopy data in combination with chemometric methods were used to classify extra-virgin olive oils according to geographical origin and harvest year. Oils were obtained from 30,different areas of northern and southern parts of the Aegean Region of Turkey for two consecutive harvest years. Fatty acid composition data analyzed with principal component analysis was more successful in distinguishing northern olive oil samples from southern samples compared to spectral data. Both methods have the ability to differentiate olive oil samples with respect to harvest year. Partial least squares (PLS) analysis was also applied to detect a correlation between fatty acid profile and spectral data. Correlation coefficients (R2) of a calibration set for stearic, oleic, linoleic, arachidic and linolenic acids were determined as 0.83, 0.97, 0.97, 0.83 and 0.69, respectively. Fatty acid profiles were very effective in classification of oils with respect to geographic origin and harvest year. On the other hand, FT-IR spectra in combination with PLS could be a useful and rapid tool for the determination of some of the fatty acids of olive oils. [source] Thermosynechoccus elongatus DpsA binds Zn(II) at a unique three histidine-containing ferroxidase center and utilizes O2 as iron oxidant with very high efficiency, unlike the typical Dps proteinsFEBS JOURNAL, Issue 4 2010Flaminia Alaleona The cyanobacterium Thermosynechococcus elongatus is one the few bacteria to possess two Dps proteins, DpsA-Te and Dps-Te. The present characterization of DpsA-Te reveals unusual structural and functional features that differentiate it from Dps-Te and the other known Dps proteins. Notably, two Zn(II) are bound at the ferroxidase center, owing to the unique substitution of a metal ligand at the A-site (His78 in place of the canonical aspartate) and to the presence of a histidine (His164) in place of a hydrophobic residue at a metal-coordinating distance in the B-site. Only the latter Zn(II) is displaced by incoming iron, such that Zn(II),Fe(III) complexes are formed upon oxidation, as indicated by absorbance and atomic emission spectroscopy data. In contrast to the typical behavior of Dps proteins, where Fe(II) oxidation by H2O2 is about 100-fold faster than by O2, in DpsA-Te the ferroxidation efficiency of O2 is very high and resembles that of H2O2. Oxygraphic experiments show that two Fe(II) are required to reduce O2, and that H2O2 is not released into solution at the end of the reaction. On this basis, a reaction mechanism is proposed that also takes into account the formation of Zn(II),Fe(III) complexes. The physiological significance of the DpsA-Te behavior is discussed in the framework of a possible localization of the protein at the thylakoid membranes, where photosynthesis takes place, with the consequent increased formation of reactive oxygen species. Structured digital abstract ,,MINT-7312099: DpsA (uniprotkb:Q8DL82) and DpsA (uniprotkb:Q8DL82) bind (MI:0407) by x-ray crystallography (MI:0114) [source] Structural Transformations during Formation of Quasi-Amorphous BaTiO3,ADVANCED FUNCTIONAL MATERIALS, Issue 7 2007D. Ehre Abstract A model of structural transformations of amorphous into quasi-amorphous BaTiO3 is suggested. The model is based on previously published data and on X-ray photoelectron spectroscopy data presented in the current report. Both amorphous and quasi-amorphous phases of BaTiO3 are made up of a network of slightly distorted TiO6 octahedra connected in three different ways: by apices (akin to perovskite), edges, and faces. Ba ions in these phases are located in the voids between the octahedra, which is a nonperovskite environment. These data also suggest that Ba ions compensate electrical-charge imbalance incurred by randomly connected octahedra and, thereby, stabilize the TiO6 network. Upon heating, the edge-to-edge and face-to-face connections between TiO6 octahedra are severed and then reconnected via apices. Severing the connections between TiO6 octahedra requires a volume increase, suppression of which keeps some of the edge-to-edge and face-to-face connections intact. Transformation of the amorphous thin films into the quasi-amorphous phase occurs during pulling through a steep temperature gradient. During this process, the volume increase is inhomogeneous and causes both highly anisotropic strain and a strain gradient. The strain gradient favors breaking those connections, which aligns the distorted TiO6 octahedra along the direction of the gradient. As a result, the structure becomes not only anisotropic and non-centrosymmetric, but also acquires macroscopic polarization. Other compounds may also form a quasi-amorphous phase, providing that they satisfy the set of conditions derived from the suggested model. [source] Intermetallic lithium compounds with two- and three-dimensional polyanions,synthesis, structure, and lithium mobilityHETEROATOM CHEMISTRY, Issue 6 2002Rainer Pöttgen Intermetallic lithium compounds are potential candidates as anode materials for battery applications. We report on the synthesis, crystal structures, and chemical bonding of lithium,transition metal,stannides and indides. These structures are composed of two- or three-dimensionally infinite polyanions formed by the transition metal and tin (indium) atoms. Besides the crystal chemistry we report on magnetic properties, 7Li solid state NMR, and 119Sn Mössbauer spectroscopy data in order to elucidate structure-property relations for this family of intermetallics. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:506,513, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10095 [source] A Thermally Stable Semiconducting PolymerADVANCED MATERIALS, Issue 11 2010Shinuk Cho The thermal stability of the poly(2,7-carbazole) derivative (PCDTBT) is investigated. UV,visible absorption spectra and X-ray photoelectron spectroscopy data demonstrate that the electronic structure of PCDTBT is stable in air at annealing temperatures up to 150,°C and in N2 even after exposure to temperatures up to 350,°C. Field-effect transistors fabricated with PCDTBT show stable characteristics and hole mobility up to 150,°C (air) and 350,°C (N2). [source] Synthesis and characterization of novel Schiff base polyurethanes,JOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2009A. V. Raghu Abstract Eight different types of novel polyurethanes (PUs) were synthesized through the polyaddition reaction of 4,4,-(ethane-1,2-diylidenedinitrilo)diphenol and 4,4,-(pentane-1,5-diylidenedinitrilo)diphenol with four different diisocyanates: 4,4,-diphenylmethane diisocyanate, toluene 2,4-diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate. The resulting PUs were soluble in polar, aprotic solvents. Structures of the diols and PUs were established with ultraviolet,visible, fluorescence, Fourier transform infrared (FTIR), 1H-NMR, and 13C-NMR spectroscopy data. FTIR and NMR spectral data indicated the disappearance of both hydroxyl and isocyanate groups in the PUs. The thermal properties were investigated with thermogravimetry and differential scanning calorimetry. The weight losses, glass transitions, onset temperatures, and crystalline melting temperatures were measured. All the PUs exhibited semicrystalline and amorphous morphologies, as indicated by X-ray diffraction. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009. [source] Deconvolution of femtosecond time-resolved spectroscopy data in multivariate curve resolution.JOURNAL OF CHEMOMETRICS, Issue 7-8 2010Application to the characterization of ultrafast photo-induced intramolecular proton transfer Abstract In femtosecond absorption spectroscopy, deconvolution of the measured kinetic traces is still an important issue as photochemical processes that may possess shorter characteristic times than the time resolution of the experiment are usually considered. In this work, we propose to perform deconvolution of the time-dependent concentration profiles extracted from multivariate curve resolution (MCR) applied to spectrokinetic data. The profiles are fitted with a model function including a description of the instrumental response function (IRF) of the experiment. The method combines the potential benefits of soft-modeling data analysis with the ones of hard-modeling for parameter estimation. The potential of the method is demonstrated first analyzing five synthetic data sets for which IRF of different widths are simulated. It is then successfully applied to resolve femtosecond UV-visible transient absorption spectroscopy data investigating the photodynamics of salicylidene aniline, a photochromic molecule of wide interest. Considering a time resolution of 150,fs for the IRF, a characteristic time of 45,fs is recovered for the first step of the photo-induced process which consists of an ultrafast intramolecular proton transfer. Our results also confirm the existence of an intermediate species with a characteristic time of 240,fs. Copyright © 2010 John Wiley & Sons, Ltd. [source] Theoretical studies on farnesyl transferase: Evidence for thioether product coordination to the active-site zinc sphereJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 7 2007Sérgio Filipe Sousa Abstract Farnesyltransferase (FTase), an interesting zinc metaloenzyme, has been the subject of great attention in anticancer research over the last decade. However, despite the major accomplishments in the field, some very pungent questions on the farnesylation mechanism still persist. In this study, the authors have analyzed a mechanistic paradox that arises from the existence of several contradicting and inconclusive experimental evidence regarding the existence of direct coordination between the active-site zinc cation and the thioether from the farnesylated peptide product, which include UV,vis spectroscopy data on a Co2+ -substituted FTase, two X-ray crystallographic structures of the FTase-product complex, and extended X-ray absorption fine structure results. Using high-level theoretical calculations on two models of different sizes, and QM/MM calculations on the full enzyme, the authors have shown that the farnesylated product is Zn coordinated, and that a subsequent step where this Zn bond is broken is coherent with the available kinetic results. Furthermore, an explanation for the contradicting experimental evidence is suggested. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007 [source] Structure elucidation of thermal degradation products of amlodipineMAGNETIC RESONANCE IN CHEMISTRY, Issue 8 2007A. Siva Lakshmi Devi Abstract Thermal degradation of amlodipine base causes intramolecular reactions affording three cyclic products, referred to as AMLDEG-I, AMLDEG-II, and AMLDEG-III, respectively. AMLDEG-I is a cyclized product formed by intramolecular elimination of ammonia from amlodipine. AMLDEG-II is a positional isomer of AMLDEG-I. AMLDEG-III is also intramolecular cyclisation product. The three degradation products were isolated by column chromatography and characterized by FT-IR and 1H and 13C NMR spectroscopy data. The AMLDEG-III was crystallized and its structure was solved by single crystal X-ray diffraction (SXRD). Copyright © 2007 John Wiley & Sons, Ltd. [source] Electronic spectra of [(CH3)2NH2]5Cd2CuCl11 crystalsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2004V. Kapustianik Abstract The temperature evolution of Cu2+ ion environment in the solid solutions of ((CH3)2NH2)5Cd2CuCl11 is studied on the basis of absorption spectroscopy data. For the detailed analysis of experimental data the special program package Crys Tool 1.0 based on quantum-mechanical models, first of all on the model of normalized spherical harmonics (NSH), has been employed. It has been found that similarly to the crystal of ((CH3)2NH2)5Cd3Cl11 (DMACC) the investigated solid solution contains tetragonally distorted octahedral metal,halogen complexes of two types and the degree of their distortion is changed considerably at the temperatures of phase transitions (PTs). The parameters of crystal field, angular overlap model, as well as the copper,chlorine distances, show continuous changes at T1 = 176 K that should be related to the second-order transition, whereas the jump-like anomalies of the spectral parameters at T2 = 115 K (on cooling) are characteristic of the first-order PTs. Introduction of the copper ions into the structure of the host DMACC crystal induces the shifts of these PTs toward low temperatures by 3.5 and 5 K, respectively. The observed structural changes around T0 = 313 K are connected with a complex co-operative effect involving weakening of the hydrogen bonds and modification of the Jahn,Teller distortion with temperature. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Exciton,phonon interaction and Raman spectra of [(CH3)2NH2]5Cd2CuCl11 crystalsPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11 2004V. Kapustianik Abstract Temperature evolution of the exciton,phonon interaction (EPI) in ((CH3)2NH2)5Cd2CuCl11 solid solution was studied on the basis of absorption spectroscopy data. The obtained values of effective phonon energies were compared with the data of Raman spectroscopy. It is shown that the (T) and E, parameters of Urbach's rule show the continuous anomalous change characteristic of the second-order phase transition at T1 = 176 K. The anomalous behaviour of the EPI and other spectral parameters at T0 = 310,315 K was related to the complex co-operative effect involving weakening of the hydrogen bonds and variation of the Jahn,Teller distortion of metal,halogen polyhedra with temperature. This process takes place only within the copper,chlorine sublattice and due to this would be hardly related to the usual phase transition. At the same time, the considered temperature change of the tetragonal distortion of the metal,halogen octahedra is followed by nonfulfillment of Urbach's rule in the temperature range TT0. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] XAFS and neutron diffraction study of the La1,xSrxCoO3PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2007V. Efimov Abstract We have studied the effects of hole doping on the crystal and electronic structure of the La1,xSrxCoO3 (x = 0.0 ÷ 0.5) by neutron Rietveld analysis and its correlation with the X-ray-absorption spectroscopy data. The abrupt decrease of the Co,O distance and an increase of the Co,O,Co angle upon substitution of La3+ by Sr2+ in La1,xSrxCoO3 are attributed to a change in the band structure at the transition from semiconducting to metallic state. Upon strontium doping, a variation of Co L2,3 -edges in La1,xSrxCoO3 series suggests an increase of the mixed low Co4+ and high or intermediate Co3+ spin states. The possible explanation of the observed changes of the crystal and electronic structure in these cobaltites is discussed. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Plasma Modification of PDMS Microfluidic Devices for Control of Electroosmotic FlowPLASMA PROCESSES AND POLYMERS, Issue 4 2007Ina T. Martin Abstract Polydimethylsiloxane (PDMS) capillary electrophoresis microchips were modified using plasma-enhanced chemical vapor deposition (PECVD), resulting in modified electroosmotic flow (EOF) values. Octafluoropropane (C3F8) and acrylic acid (AA) plasmas were chosen as initial test systems for device modification. Argon plasma pretreatments were used to improve adhesion of the fluorocarbon (FC) and AA films. Contact angle measurements and X-ray photoelectron spectroscopy data demonstrated that the Ar/C3F8 plasma treatment of PDMS results in the deposition of a hydrophobic, crosslinked FC film, whereas the Ar/AA plasma treatment results in the deposition of a hydrophilic film with ionizable acid groups. The extent of plasma modification within the device channels was explored using scanning Auger microscopy and dye absorption measurements. EOF values were measured for plasma-treated chips as a function of pH, and aging studies were performed to determine the durability of the plasma treatments. Results show that EOF is decreased in Ar/C3F8 plasma-treated chips, and varies less with pH than untreated devices. Additionally, EOF measurements are constant for a minimum of 5 d. In contrast, EOF for Ar/AA plasma-treated devices is dependent on pH. EOF measurements of C3F8 and AA treated chips without the Ar pretreatment are less stable, particularly in the AA case. In addition to improving adhesion, the Ar plasma treatment results in a decreased hydrophobic dye absorption into the PDMS, which is attributed to the physical crosslinking of the polymer by the Ar plasma. [source] Fluorescence-based soft-sensor for monitoring ,-lactoglobulin and ,-lactalbumin solubility during thermal aggregationBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2008Rand Elshereef Abstract A soft-sensor for monitoring solubility of native-like ,-lactalbumin (,-LA) and ,-lactoglobulin (,-LG) and their aggregation behavior following heat treatment of mixtures under different treatment conditions was developed using fluorescence spectroscopy data regressed with a multivariate Partial Least Squares (PLS) regression algorithm. PLS regression was used to correlate the concentrations of ,-LA and ,-LG to the fluorescence spectra obtained for their mixtures. Data for the calibration and validation of the soft sensor was derived from fluorescence spectra. The process of thermal induced aggregation of ,-LG and ,-LA protein in mixtures, which involves the disappearance of native-like proteins, was studied under various treatment conditions including different temperatures, pH, total initial protein concentration and proportions of ,-LA and ,-LG. It was demonstrated that the multivariate regression models used could effectively deconvolute multi-wavelength fluorescence spectra collected under a variety of process conditions and provide a fairly accurate quantification of respective native-like proteins despite the significant overlapping between their emission profiles. It was also demonstrated that a PLS model can be used as a black-box prediction tool for estimating protein aggregation when combined with simple mass balances. Bioeng. 2008;99: 567,577. © 2007 Wiley Periodicals, Inc. [source] Water-in-ionic liquid microemulsion-based organogels as novel matrices for enzyme immobilizationBIOTECHNOLOGY JOURNAL, Issue 8 2010Ioannis V. Pavlidis Abstract The use of water-in-ionic liquid microemulsion-based organogels (w/IL MBGs) as novel supports for the immobilization of lipase B from Candida antarctica and lipase from Chromobacterium viscosum was investigated. These novel lipase-containing w/IL MBGs can be effectively used as solid phase biocatalysts in various polar and non-polar organic solvents or ILs, exhibiting up to 4.4-fold higher esterification activity compared to water-in-oil microemulsion-based organogels. The immobilized lipases retain their activity for several hours at 70°C, while their half life time is up to 25-fold higher compared to that observed in w/IL microemulsions. Fourier-transform infrared spectroscopy data indicate that immobilized lipases adopt a more rigid structure, referring to the structure in aqueous solution, which is in correlation with their enhanced catalytic behavior observed. [source] Haemodynamic changes in the brain after vaginal delivery and caesarean section in healthy term infantsBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 2 2002C. Dani Objective To investigate whether the mode of delivery may affect neonatal cerebral haemodynamics during the first hour of life. Design Prospective study. Sample Healthy infants with gestational age ,37 weeks and birthweight appropriate for gestational age, born after uncomplicated pregnancy by vaginal delivery or elective caesarean section, two to five hours after the delivery. Methods Near infra-red spectroscopy was used to measure changes of oxygenated haemoglobin, deoxygenated haemoglobin, oxidized-reduced cytochrome aa3, and mean cerebral oxygen saturation (mixed cerebral oxygen saturation = oxygenated haemoglobin/total haemoglobin). Changes in cerebral blood volume were calculated. Results Near infra-red spectroscopy data did not show significant differences between infants born by vaginal delivery or by caesarean section. There was a significant decrease of oxygenated haemoglobin and change of cerebral blood volume values at 120 and 180 minutes in both the groups, while deoxygenated haemoglobin and oxidized-reduced cytochrome aa3 were unchanged. Conclusions A decrease of cerebral blood volume occurs after birth and this occurs both in infants born by vaginal delivery and by caesarean section. [source] Metallomacrocycles with a Difference: Macrocyclic Complexes with Exocyclic Ruthenium(II)-Containing DomainsCHEMISTRY - A EUROPEAN JOURNAL, Issue 43 2009Edwin Abstract The templated synthesis of organic macrocycles containing rings of up to 96 atoms and three 2,2,-bipyridine (bpy) units is described. Starting with the bpy-centred ligands 5,5,-bis[3-(1,4-dioxahept-6-enylphenyl)]-2,2,-bipyridine and 5,5,-bis[3-(1,4,7-trioxadec-9-enylphenyl)]-2,2,-bipyridine, we have applied Grubbs' methodology to couple the terminal alkene units of the coordinated ligands in [FeL3]2+ complexes. Hydrogenation and demetallation of the iron(II)-containing macrocyclic complexes results in the isolation of large organic macrocycles. The latter bind {Ru(bpy)2} units to give macrocyclic complexes with exocyclic ruthenium(II)-containing domains. The complex [Ru(bpy)2(L)]2+ (isolated as the hexafluorophosphate salt), in which L=5,5,-bis[3-(1,4,7,10-tetraoxatridec-12-enylphenyl)]-2,2,-bipyridine, undergoes intramolecular ring-closing metathesis to yield a macrocycle which retains the exocyclic {Ru(bpy)2} unit. The poly(ethyleneoxy) domains in the latter macrocycle readily scavenge sodium ions, as proven by single-crystal X-ray diffraction and atomic absorption spectroscopy data for the bulk sample. In addition to the new compounds, a series of model complexes have been fully characterized, and representative single-crystal X-ray structural data are presented for iron(II) and ruthenium(II) acyclic and macrocyclic species. [source] | |||||||||||||||||||