bluuebunny/crossref_metadata_2025_split huggingface dataset:
Raman spectroscopy of uranopilite of different origins—implications for molecular structure
Authors: Frost Ray L. , Čejka Jiří , Weier Matt L. , Martens Wayde N. , Ayoko Godwin A. 
Published: December 2006

AbstractUranopilite, [(UO2)6(SO4)O2(OH)6(H2O)6](H2O)8, the composition of which may vary, can be understood as a complex hydrated uranyl oxyhydroxy sulfate. The structure of uranopilite from different locations has been studied by Raman spectroscopy at 298 and 77 K. A single intense band at 1009 cm−1 assigned to the ν1 (SO4)2− symmetric stretching mode shifts to higher wavenumbers at 77 K. Three low‐intensity bands are observed at 1143, 1117 and 1097 cm−1. These bands are attributed to the (SO4)2− ν3 anti‐symmetric stretching modes. Multiple bands provide evidence that the symmetry of the sulfate anion in the uranopilite structure is lowered. Three bands are observed in the region 843 to 816 cm−1 in both the 298 and 77 K spectra and are attributed to the ν1 symmetric stretching modes of the (UO2)2+ units. Multiple bands prove the symmetry reduction of the UO2 ion. Multiple OH stretching modes prove a complex arrangement of OH groupings and hydrogen bonding in the crystal structure. A series of infrared bands not observed in the Raman spectra are found at 1559, 1540, 1526 and 1511 cm−1 attributed to δ UOH bending modes. U‐O bond lengths in uranyl and OH/dotbondO bond lengths are calculated and compared with those from X‐ray single crystal structure analysis. The Raman spectra of uranopilites of different origins show subtle differences, proving that the spectra are origin‐ and sample‐dependent. Hydrogen‐bonding network and its arrangement in the crystal structure play an important role in the origin and stability of uranopilite. Copyright © 2006 John Wiley & Sons, Ltd.
Line shape analyses on the CO stretching bands of acetone using a vibrational coupling model
Authors: Kobayashi Kaori , Kanesaka Isao 
Published: December 2006

AbstractThe line shapes of the polarized and depolarized Raman bands of the CO stretching of acetone, as well as the infrared band, are analyzed on the basis of the vibrational coupling model. The analytical procedures are described in detail. Satisfactory agreement between the observed and simulated spectra is obtained using almost the same coupling scheme for the three types of spectra. The orientational correlation between the coupled oscillators is discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Spectroscopic and computational studies on self‐assembly complexes of bis(pyrrol‐2‐ ylmethyleneamine) ligands linked by alkyl spacers with Cu(II)
Authors: Li Wei , Wang Yibo , Yang Lanying , Szeghalmi Adriana , Ye Yong , Ma Jinshi , Luo Mingdao , Hu Ji‐ming , Kiefer Wolfgang 
Published: December 2006

AbstractBis(pyrrol‐2‐ylmethyleneamine) ligands and their mononuclear monomeric and dinuclear dimeric self‐assembly complexes with Cu(II) were investigated by means of IR and Raman spectroscopies and density functional theory. The ground‐state geometries were calculated by using the BeckeLeeYangParr composite exchange‐correlation functional (B3LYP) and a combined basis set (LanL2DZ for Cu; 6–31G(d) for C, H, N), and they were compared with the single‐crystal X‐ray diffraction (XRD) structures. The DFT‐calculated CuN bond lengths are generally higher by 0.001–0.040 Å than those determined through XRD. The vibrational spectra were also calculated at the same level of theory for the optimized geometries. The calculated wavenumbers were scaled by a uniform scaling factor and compared with the experimental fundamentals. The predicted spectra are in good agreement with the experimental ones with the deviations generally less than 30 cm−1. In comparison with the spectra of the ligands, the coordination effect shifts the υ(CN) wavenumber by about 50 cm−1 toward a lower value. Because of the weak intermolecular CH···Cu hydrogen bond, the CuN stretching mode is shifted toward a lower wavenumber. Copyright © 2006 John Wiley & Sons, Ltd.
Nanomechanics of single keratin fibres: A Raman study of the α‐helix →β‐sheet transition and the effect of water
Authors: Paquin Raphaël , Colomban Philippe 
Published: December 2006

AbstractThe use of micro‐Raman spectroscopy, through chemical‐bond, nano‐scale probes, allows the changes in conformations (α‐helix →β‐sheet), chain orientation, breakage of disulfide bonds (20%) and the increase of intra‐ and inter‐chain distances during the application of stress to be distinguished. The combination of micro‐Raman spectroscopy and a Universal Fibre Tester allows a quantitative measurement of the extension of chemical bonds in the peptide chain during loading. The nano‐structural transformations of keratin during strain of human hair in a dry environment (40–60% relative humidity) and saturated with water have been studied. Water permits the sliding of the chains and decreases the bond energy of the hair. Spectral analyses and 2D correlation are two coherent and independent methods to follow the structural nano‐mechanical (Raman) and micro‐mechanical (strain/stress) analyses, and confirm the validity of the experimental results, tools and principles used, as well as the agreement with the structural model of keratin fibres described by Chapman and Hearle. Copyright © 2006 John Wiley & Sons, Ltd.
N‐Isopropylacrylamide/2‐Hydroxyethyl Methacrylate Star Diblock Copolymers: Synthesis and Thermoresponsive Behavior
Authors: Cao Zhiqiang , Liu Wenguang , Ye Guixiang , Zhao Xiaoli , Lin Xiaoze , Gao Peng , Yao Kangde 
Published: December 2006

AbstractSummary: Tri‐arm star diblock copolymers, poly(2‐hydroxyethyl methacrylate)‐block‐poly(N‐isopropylacrylamide) [P(HEMA‐b‐NIPAAm)] with PHEMA and PNIPAAm as separate inner and outer blocks were synthesized via a two‐step ATRP at room temperature. The formation, molecular weight and distribution of polymers were examined, and the kinetics of the reaction was monitored. The PDI of PHEMA was shown to be lower, indicating well‐controlled polymerization of trifunctional macro‐initiator and resultant star copolymers. The thermoresponsive behavior of diblock copolymer aqueous solution were studied by DSC, phase diagrams, temperature‐variable 1H NMR, TEM and DLS. The results revealed that introducing a higher ratio of HEMA into copolymers could facilitate the formation of micelles and the occurrence of phase transition at lower temperatures. TEM images showed that I‐(HEMA40‐NIPAAm320)3 solutions developed into core‐shell micelles with diameters of approximately 100 nm. I‐(HEMA40‐NIPAAm320)3 was used as a representative example to elucidate the mechanism underlying temperature‐induced phase transition of copolymer solution. In this study we proposed a three‐stage transition process: (1) separately dispersed micelles state at ≈17–22 °C; (2) aggregation and fusion of micelles at ≈22–29 °C; (3) sol‐gel transition of PNIPAAm segments at ≈29–35 °C, and serious syneresis of shell layers.Molecular architecture of Poly(HEMA‐b‐NIPAAm).magnified imageMolecular architecture of Poly(HEMA‐b‐NIPAAm).
Binary Blends of Polymer Semiconductors: Nanocrystalline Morphology Retards Energy Transfer and Facilitates Efficient White Electroluminescence
Authors: Alam Maksudul M. , Jenekhe Samson A. 
Published: December 2006

AbstractSummary: Blends of poly(9,9‐dioctylfluorene) (PFO) and poly(2‐methoxy‐5(2′‐ethyl‐hexyloxy)‐1,4‐phenylenevinylene) (MEH‐PPV) were found to phase separate into 40–50 nm crystalline PFO domains and to exhibit efficient white electroluminescence when the composition is below 30 wt.‐% MEH‐PPV. The 5 wt.‐% nanocrystalline blends had a luminance of 4 000 cd · m−2, an external quantum efficiency of 3.1%, and a current efficiency of 3.7 cd · A−1. Transmission electron microscopy, electron diffraction, and atomic force microscopy of blends with higher MEH‐PPV content and the two homopolymers showed them to be amorphous. Only orange‐red electroluminescence, characteristic of MEH‐PPV, was observed from the amorphous blends due to efficient energy transfer from PFO. These results demonstrate that energy transfer processes in binary PFO:MEH‐PPV blends and light‐emitting devices based on them can be controlled through the morphology and composition.TEM image of a PFO:MEH‐PPV blend.magnified imageTEM image of a PFO:MEH‐PPV blend.
Mortality in patients with Parkinson's disease treated by stimulation of the subthalamic nucleus
Authors: Schüpbach Michael W.M. , Welter Marie Laure , Bonnet Anne Marie , Elbaz Alexis , Grossardt Brandon R. , Mesnage Valerie , Houeto Jean Luc , Maltête David , Mallet Luc , Rocca Walter A. , Mallet Alain , Agid Yves 
Published: December 2006

AbstractSubthalamic nucleus (STN) stimulation improves motor disability and quality of life in patients with advanced Parkinson's disease (PD). Short‐term mortality is low, but little is known about long‐term mortality. We assessed mortality and causes of death in 171 consecutive PD patients treated by STN stimulation. Surgery was performed after a median lagtime of 13 years from PD onset at a median age of 57 years. The median follow‐up after surgery was 41 months. Sixteen patients died 8 to 83 months after neurosurgery. Poorer cognitive function was the only predictive factor for mortality (standardized mortality ratio = 2.9; 95% confidence interval [CI], 1.6–4.7; P < 0.0001). Based on a historical comparison of 118 operated patients with 39 nonoperated patients from a different population, survival among operated patients was not better (hazard ratio = 1.2; 95% CI, 0.7–2.1). © 2006 Movement Disorder Society
Complete assignments of 1H and 13C NMR spectroscopic data for two new triterpenoid saponins from Ilex hainanensis
Authors: Zhou Sixiang , Yang Junshan , Liu Fucheng , Tu Pengfei 
Published: December 2006

AbstractTwo novel unsaturated E‐ring pentacyclic triterpenoid saponins, ilexhainanoside A and ilexhainanoside B, were isolated from the leaves of Ilex hainanensis. Their chemical structures were determined by MS, NMR spectroscopy and chemical analysis. Complete assignments of the 1H and 13C NMR spectroscopic data were achieved by 1D and 2D NMR experiments (HSQC, HMBC, ROESY and 1H–1H COSY). Copyright © 2006 John Wiley & Sons, Ltd.
Conformational study of 2‐arylazo‐1‐vinylpyrroles
Authors: Rusakov Yury Yu. , Krivdin Leonid B. , Senotrusova Elena Yu. , Schmidt Elena Yu. , Vasiltsov Alexander M. , Mikhaleva Albina I. , Trofimov Boris A. , Dyachenko Oleg A. , Chekhlov Anatolii N. , Kazheva Olga N. 
Published: December 2006

AbstractConformational study of 2‐phenylazo‐1‐vinylpyrrole and 2‐(4‐bromophenyl)azo‐5‐methyl‐1‐vinylpyrrole was performed on the basis of the experimental measurements and high‐level ab initio calculations of their 13C13C and 13C1H spin–spin coupling constants, showing marked stereochemical behaviour upon the internal rotation of the vinyl group and the pyrrolyl moiety. In liquid phase, both compounds were found to adopt predominant s‐trans‐s‐trans conformation with the noticeable population (ca. 30%) of the higher‐energy s‐cis‐s‐trans conformation in the latter compound. As follows from the X‐ray data, 2‐phenylazo‐1‐vinylpyrrole crystallizes in s‐trans‐s‐trans conformation while the crystalline molecular structure of 2‐(4‐bromophenyl)azo‐5‐methyl‐1‐vinylpyrrole is s‐cis‐s‐trans. Copyright © 2006 John Wiley & Sons, Ltd.
Low frequency tangential filtering decomposition
Authors: Achdou Y. , Nataf F. 
Published: December 2006

AbstractFor block‐tridiagonal systems of linear equations arising from the discretization of partial differential equations, a composite preconditioner is proposed and tested. It combines a classical ILU0 factorization for high frequencies with a tangential filtering preconditioner. The choice of the filtering vector is important: the test‐vector is the Ritz eigenvector corresponding to the approximate lowest eigenvalue, obtained after a limited number of iterations of a ILU0 preconditioned Krylov method. Numerical tests are carried out for this method. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and characterization of poly(higher‐α‐olefin)s with a nickel(α‐diimine)/methylaluminoxane catalyst system: Effect of chain running on the polymer properties
Authors: Subramanyam Ummadisetty , Sivaram Swaminathan 
Published: December 2006

AbstractHomopolymerization of octadecene‐1 at different reaction conditions has been studied. Significant chain running can be seen at higher polymerization temperatures. Interestingly, insertion of octadecene‐1 into a sterically hindered nickel‐cation/carbon (secondary) bond is observed. The microstructure of the polymer was established using NMR spectroscopy. The effects of chain running on polymer melting, crystallization behavior, and dynamic mechanical thermal properties were studied using DSC and DMTA. The extent of chain running (i.e., 2,ω‐, 1,ω‐enchainments) decreases with an increase in the carbon number of α‐olefins. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 191–210, 2007
Collagen models as a probe in the decay of works of art: synthesis, conformation and immunological studies
Authors: Zevgiti Stella , Sakarellos Constantinos , Sakarellos‐Daitsiotis Maria , Ioakimoglou Eleni , Panou‐Pomonis Eugenia 
Published: December 2006

AbstractProteinaceous substances such as collagen, casein and albumin have been widely used as binding media in a variety of works of art. Damages of these ‘sensitive’ materials, mainly caused of the influence of the environment, are responsible for the overall decay of works of art, and their identification is essential to understand ancient technologies, determine the extent of deterioration and help in future restoration and preservation processes. The most commonly used techniques for the identification of proteinaceous binding media are staining techniques, chromatography, spectrometry and immunological methods, although for the latter no systematic studies have been carried out until now. Aiming at contributing to the development of a reliable and reproducible immunoassay for the evaluation of the collagen‐based decay of works of art, sequential polypeptides (Pro‐X‐Gly)n where X represents amino acid residues Val, Lys, Glu and (Hyp‐Val‐Gly)n were prepared as models of collagen fragments derived from artificially and naturally aged animal collagens. Conformational studies of the polypeptides by CD revealed the occurrence of polyproline II‐like structures comparable with those of collagen. Polypeptides and collagen I were administered to animals, and the induced antibodies were used for the immunochemical detection and differentiation of collagen and collagen fragments. The combined application of (i) anti‐collagen antibodies, which strongly interact with native collagen, but poorly recognized by artificially aged collagen and (ii) anti‐polypeptide antibodies, which do not associate with native collagen, but are strongly recognized by collagen fragments in naturally or artificially aged collagen, is a valuable tool in determining the extent of decay in works of art. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Analogs of arginine vasopressin modified in the N‐terminal part of the molecule with a conformationally constrained cis‐peptide bond motif
Authors: Sobolewski Dariusz , Prahl Adam , Derdowska Izabela , Slaninová Jiřina , Kaczmarek Krzysztof , Zabrocki Janusz , Lammek Bernard 
Published: December 2006

AbstractThe present work is part of our studies aimed at clarifying the influence of steric constraints in the N‐terminal part of arginine vasopressin (AVP) and its analogs on the pharmacological activity of the resulting peptides. We describe the synthesis of eight new analogs of AVP or [3‐mercaptopropionic acid (Mpa)1]AVP (dAVP) substituted at positions 2 and 3 or 3 and 4 with two diastereomers of 4‐aminopyroglutamic acid. The steric constraints provided by this modification turned out, however, so strong that all the peptides were inactive in all of the bioassays (pressor, antidiuretic and uterotonic tests). Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd.
Raman study of β‐Sr0.33V2O5 micro‐crystals under high pressure
Authors: Kontos A. G. , Lampakis D. , Popović Z. V. , Raptis Y. S. , Liarokapis E. , Isobe M. , Ueda Y. 
Published: December 2006

AbstractThe phonon dynamics of the strontium vanadium oxide bronze (β‐Sr0.33V2O5) is studied using Raman spectroscopy at different temperature under high pressure up to 5.7 GPa. Interesting features of the spectra, such as the narrowing of some modes that harden under pressure (250–300 cm–1) or the softening of a low‐frequency mode, are presented and discussed. Our low temperature measurements confirm that under high hydrostatic pressure the charge ordered phase is suppressed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure effects on surfactant solubilized single‐wall carbon nanotubes
Authors: Freire P. T. C. , Lemos V. , Lima J. A. , Saraiva G. D. , Pizani P. S. , Nascimento R. O. , Ricardo N. M. P. S. , Mendes Filho J. , Souza Filho A. G. 
Published: December 2006

AbstractRaman scattering investigations of surfactant solubilized SWCNTs under hydrostatic pressure were performed. The wave number dependence on pressure for the tangential bands was observed to be discontinuous at 2 GPa, with change of slope for higher pressures. This change coincides with the calculated critical pressure for collapse of the tubes. Therefore, it could be considered as indicative of deformation of the tube along the radial direction. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fertility and testicular fatty acid composition in the chicken as influenced by vitamin E and ethoxyquin
Authors: Tinsley I. J. , Arscott G. H. , Lowry R. R. 
Published: December 2006

AbstractThe fatty acid composition of testicular lipids has been determined and related to fertility data from groups of dubbed White Leghorn cockerels after a 50‐week feeding period on rations containing 10% safflower oil or coconut oil. Supplements of ethoxyquin ord‐α‐tocopherol acetate maintained fertility in birds raised on rations containing safflower oils. This response was associated with higher proportions of 22∶4 ω6 and lower proportions of 18∶2 ω6 in testicular lipids. Testes size was quite variable in the unsupplemented group with changes in fatty acid composition being more pronounced in the smaller testes. A multiple regression was calculated using data from those birds on the safflower oil ration. With a correlation ratio of 0.90 fertility was expressed as a function of testes size, semen concentration and the proportions of 18∶2 ω6, 20∶4 ω6 and 22∶4 ω6 in testicular lipids. Despite the low intake of linoleate significant levels of polyunsaturated fatty acids were maintained in testicular lipids of birds fed the coconut oil rations. The major changes in fatty acid composition of testicular lipids produced by this variable was a decrease in the proportion of 18∶2 ω6 and an increase in the proportion of 18∶1.
Eiution characteristics of fatty acid methyl esters on capillary columns
Authors: Nelson Gary J. 
Published: December 2006

AbstractThe elution characteristics of fatty acid methyl esters on support‐coated and open tubular capillary columns were investigated using reference standards and natural mixtures of fatty acid methyl esters. Over an extended range of fatty acid methyl esters chain lengths (C‐11–C‐26), the plot of the log of the adjusted retention time, t′R, vs. number of carbon atoms in the fatty acid chain was not linear, as has been previously assumed by many investigators. With support‐coated open tubular columns and with diethylene glycol succinate as the stationary phase, the relationship between the log of the retention time and carbon number was best approximated by a second‐order equation: log (t′R)x=α+β(CNx)+γ(CNx)2 where α, β, and γ are the virial coefficients of the equation. In addition, for the longer fatty acid methyl esters, the plots all tended to converge. Hence, for data from capillary columns, especially over a wide range of carbon numbers, all tentative indications based upon linear log plots and parallel lines for different homologous series of fatty acid isomers should be viewed with caution. A method is presented for identifying peaks from capillary columns; it uses quadratic equations and three reference fatty acid methyl ester standards for each homologous series being studied.
Cholanoic (bile) acids in hepatic and nonhepatic tissues of miniature swine
Authors: Dupont Jacqueline , Oh Suk‐Yon , O'Deen Louise A. , Geller Sigmund 
Published: December 2006

AbstractPreliminary information is given indicating that all tissues of the miniature swine examined thus far contain cholanoic (bile) acids. Thin layer and gas chromatographic analyses suggest that the cholanoic acids are conjugated with glycine and taurine. The amounts appear to be substantial and should be assessed in regard to studies of cholesterol turnover.
Dietary fats and properties of endoplasmic reticulum: II. Dietary lipid induced changes in activities of drug metabolizing enzymes in liver and duodenum of rat
Authors: Hietanen E. , Laitinen M. , Vainio H. , Hänninen O. 
Published: December 2006

AbstractRats were fed cholesterol, cacao butter, or olive oil diets to determine the effect of dietary lipids on the rate of drug biotransformation in the liver and duodenum. The cholesterol rich diet maintained the hepatic aryl hydrocarbon hydroxylase activity at the same level as did the standard diet. Rats fed olive oil and cacao butter diets showed lower hepatic aryl hydrocarbon hydrorylase activity. The p‐nitroanisole 0‐demethylase activity was doubled in hepatic microsomes of rats fed the high cholesterol diet when compared to rats fed the standard diet. The hepatic uridine diphosphate glucoronosyltransferase activity showed different patterns depending on the in vitro treatment of the microsomal membranes. If the enzyme activity was assayed from the native, untreated microsomes, an increase in the measurable uridine diphosphate glucuronosyl transferase activity was found in rats having cholesterol rich diet. After the in vitro activation of membrane‐bound uridine diphosphate glucuronosyltransferase by trypsin, the increase in measurable activity was 10 fold in the group fed the standard diet, 6 fold in group fed cholesterol, 4 fold in group fed cacao butter, and 3 fold in group fed olive oil. Trypsin digestion of microsomes increased the measurable uridine diphosphate glucuronosyltransferase activity less in rats fed diets rich in neutral fats than those fed the standard diet. In the duodenal mucosa, lipid diets decreased the activities of drug hydroxylation and glucuronidation.
Taxus baccata seed oil: A new source ofcis‐5,cis‐9‐octadecadienoic acid
Authors: Madrigal R. V. , Smith C. R. 
Published: December 2006

AbstractMethyl esters prepared from the seed oil of the coniferTaxus baccata L. were found by gas liquid chromatography to contain 12% of a component which, when isolated by preparative thin layer chromatography and characterized by mass spectrometry, ozonolysis and nuclear magnetic resonance, was identified ascis‐5,cis‐9‐octadecadienoic acid.
Isolation of human serum low‐density lipoproteins with the aid of an immune‐specific adsorber
Authors: Kostner Gerhard , Holasek Anton 
Published: December 2006

AbstractHuman serum lipoproteins containing B‐protein have been isolated using an immunoadsorber. Bromoacetyl cellulose was combined with pure antibodies to low density lipoprotein (LDL) and an immunoadsorber of high capacity was obtained. With 1 g of this immunoadsorber all LDL and very low density lipoprotein (VLDL) from 30 ml pooled human serum were adsorbed and then eluted with glycine‐HCl buffer pH 3.2 at 0 C. The isolated lipoproteins were investigated by electrophoresis, immunodiffusion and ultracentrifugation, and found to be identical to LDL+VLDL isolated by ultracentrifugation.