bluuebunny/crossref_metadata_2025_split huggingface dataset:
Asymmetric graph coloring games
Authors: Kierstead H. A. 
Published: January 2005

AbstractWe introduce the (a,b)‐coloring game, an asymmetric version of the coloring game played by two players Alice and Bob on a finite graph, which differs from the standard version in that, in each turn, Alice colors a vertices and Bob colors b vertices. We also introduce a related game, the (a,b)‐marking game. We analyze these games and determine the (a,b)‐chromatic numbers and (a,b)‐coloring numbers for the class of forests and all values of a and b. © 2005 Wiley Periodicals, Inc. J Graph Theory 48: 169–185, 2005
Circular choosability of graphs
Authors: Zhu Xuding 
Published: January 2005

AbstractThis paper discusses the circular version of list coloring of graphs. We give two definitions of the circular list chromatic number (or circular choosability) χc, l(G) of a graph G and prove that they are equivalent. Then we prove that for any graph G, χc, l(G) ≥ χl(G) − 1. Examples are given to show that this bound is sharp in the sense that for any ϵ 0, there is a graph G with χc, l(G) > χl(G) − 1 + ϵ. It is also proved that k‐degenerate graphs G have χc, l(G) ≤ 2k. This bound is also sharp: for each ϵ < 0, there is a k‐degenerate graph G with χc, l(G) ≥ 2k − ϵ. This shows that χc, l(G) could be arbitrarily larger than χl(G). Finally we prove that if G has maximum degree k, then χc, l(G) ≤ k + 1. © 2005 Wiley Periodicals, Inc. J Graph Theory 48: 210–218, 2005
Synthesis of Block Copolymers containing Chain‐Controlled Aramid and Fluoroethylene Segments
Authors: Korematsu Arata , Furuzono Tsutomu , Kishida Akio 
Published: January 2005

AbstractSummary: Novel block copolymers containing aromatic polyamide (aramid) and fluoroethylene segments were synthesized by a two‐step solution polycondensation. This synthetic method could control the chain‐length of aramid segments and these copolymers could have high structural regularity. The number‐average molecular weight ($\overline M _{\rm n}$) of one of these polymers is over 2.0 × 104. Incorporating fluoroethylene segments improves the solubility of the resulting polymer compared with conventional aramids.The synthesis of the fluoroethylene‐aramid block copolymers.magnified imageThe synthesis of the fluoroethylene‐aramid block copolymers.
Amygdalar and hippocampal MRI volumetric reductions in Parkinson's disease with dementia
Authors: Junqué Carme , Ramírez‐Ruiz Blanca , Tolosa Eduardo , Summerfield Christopher , Martí María‐José , Pastor Pau , Gómez‐Ansón Beatriz , Mercader José Ma. 
Published: January 2005

AbstractParkinson's disease (PD) involves neuropathological changes in the limbic system that lead to neuronal loss and volumetric reductions of several nuclei. We investigated possible volumetric reductions of the amygdala and hippocampus associated to PD. We carried out magnetic resonance imaging (MRI) volumetric studies in 16 patients with PD and dementia (PDD), 16 patients with PD without dementia (PD), and 16 healthy subjects. The general analysis of variance (ANOVA) showed a significant group effect (for the amygdala, P = 0.01; for the hippocampus, P = 0.005). A post‐hoc test demonstrated that the differences were due to PDD and control group comparisons for the amygdala (P = 0.008) and for the hippocampus (P = 0.004). In nondemented PD subjects, we observed an 11% reduction in the amygdala and a 10% reduction in the hippocampus compared with that in controls. In summary, demented PD patients have clear amygdalar and hippocampal atrophy that remains statistically significant after controlling for global cerebral atrophy. Nondemented PD patients also showed a degree of volumetric reduction in these structures although the differences were not statistically significant. © 2005 Movement Disorder Society
GABAergic interneurons in human subthalamic nucleus
Authors: Lévesque Julie‐Christine , Parent André 
Published: January 2005

AbstractThe subthalamic nucleus (STN) is considered a homogeneous structure composed essentially of projection neurons that exert a profound glutamate‐mediated excitatory influence upon the main output structures of the basal ganglia. It is currently the most efficient target for deep brain stimulations designed to alleviate symptoms of Parkinson's disease. STN neurons were analyzed by applying stereological methods and single/double‐immunostaining procedures to postmortem material obtained from normal individuals. Besides a multitude of closely packed projection neurons (∼24.7 μm in diameter), the human STN (mean volume, 174.5 ± 20.4 mm3; total neuronal density, 239.5 ± 31.9 × 103) contained smaller neurons (∼12.2 μm), which displayed glutamic acid decarboxylase (GAD)65/67 immunoreactivity and shared the morphological features of interneurons described in Golgi studies of primate STN. These putative γ‐aminobutyric acid (GABA)ergic interneurons accounted for 7.5% of the total neuronal population of the STN. Although present throughout the nucleus, they were significantly more numerous in its posterior‐ventral‐medial sector, which belongs to the limbic/associative functional territory. Many projection neurons located dorsolaterally in the STN showed parvalbumin immunoreactivity and others lying ventromedially displayed calretinin immunostaining, but none of the GAD‐positive interneurons expressed these calcium‐binding proteins. Although less abundant than projection neurons, GABAergic interneurons might play a important role in the intrinsic organization of the STN. The morphological and chemical heterogeneity of the human STN reported here might have important implications in the functional organization of the basal ganglia. © 2005 Movement Disorder Society
Falls in degenerative cerebellar ataxias
Authors: van de Warrenburg Bart P.C. , Steijns Janneke A.G. , Munneke Marten , Kremer Berry P.H. , Bloem Bastiaan R. 
Published: January 2005

AbstractWe retrospectively and prospectively assessed the frequency and characteristics of falls in patients with degenerative cerebellar ataxias. The results show that falls occur very frequently in patients with degenerative cerebellar ataxias and that these falls are serious and often lead to injuries or a fear of falling. Clinicians should be aware of this problem in ataxia patients and should try to prevent falls. © 2005 Movement Disorder Society
Effect of titania nanoparticles on the morphology of low density polyethylene
Authors: Ma Dongling , Akpalu Yvonne. A. , Li Ying , Siegel Richard W. , Schadler Linda S. 
Published: January 2005

AbstractThe role of TiO2 nanoparticle surfaces in affecting the crystalline structure of low‐density polyethylene (LDPE) has been investigated by varying the nanoparticle surface from hydrophilic (as‐received) to less hydrophilic (dried) or more hydrophilic (polar silane treated). Differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WXRD) were used to determine the degree of crystallinity and crystalline structure. The impact of nanoparticle aggregates on the nanometer to micrometer organization of LDPE crystals was studied with atomic force microscopy (AFM) and small‐angle light scattering (SALS). This characterization showed that the presence of the TiO2 nanoparticles, with the various different surface conditions investigated, did not alter the degree of LDPE crystallinity, the unit cell dimensions, the average lamellar thickness, or the average spherulite size. However, the nanoparticles did affect the internal arrangement of intraspherulitic crystalline aggregates by decreasing the relative optic axis orientation of these crystals, usually referred to as internal spherulite disorder. The LDPE filled with the nanoparticles treated with a polar silane (N‐(2‐aminoethyl) 3‐aminopropyl‐trimethoxysilane (AEAPS)) showed the highest internal spherulitic disorder and exhibited the most poorly developed spherulite structure. The combination of SALS with AFM has allowed a detailed characterization of the morphology of the semicrystalline polymer nanocomposites. Information on the internal organization of the spherulites, the size of the nanoparticle aggregates, and the location of the nanoparticle aggregates can be uniquely obtained when both techniques are used. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 488–497, 2005
Investigation of the dynamics of poly(ether sulfone) membrane formation by immersion precipitation
Authors: Li Zhansheng , Jiang Chengzhang 
Published: January 2005

AbstractCast‐leaching experiments were carried out to investigate the dynamics of membrane formation by immersion precipitation, with an emphasis on the outflow of the solvent from casting solutions during the phase‐separation process. The casting solutions, consisting of poly(ether sulfone) as the polymer, N‐methyl‐2‐pyrolidone as the solvent, and water (H2O), isopropyl alcohol, 1‐butanol, and diethylene glycol as nonsolvent additives (NSAs), were immersed in a coagulation bath. Two thermodynamically vastly different coagulantsH2O, a strong coagulant, and ethylene glycol, a weak coagulant—were used to study the effect of the coagulant on the dynamics of membrane formation. The results showed that the outflow of the solvent during the initial stage of membrane formation was controlled by Fickian diffusion within the extremely wide range of conditions studied, that is, polymer concentrations of 10–38%, approaching ratios of 0–0.95, and thermodynamically vastly different NSAs and coagulants. The role of the initial state of the membrane‐forming solution, especially the conformational state of macromolecules in the membrane‐forming process, was examined. In contrast to those works on the behavior of small molecules, an attempt was made to qualitatively interpret membrane formation from the viewpoint of macromolecules. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 498–510, 2005
High Curie temperature Pb(Fe1/2Nb1/2)O3‐based ferroelectrics: 0.40Pb(Fe1/2Nb1/2)O3–0.34PbZrO3–0.26PbTiO3
Authors: Fang Bijun , Shan Yuejin , Tezuka Keitaro , Imoto Hideo 
Published: January 2005

AbstractHigh‐Tm (∼270 °C) relaxor ferroelectrics 0.40Pb(Fe1/2Nb1/2)O3–0.34PbZrO3–0.26PbTiO3 (PFN40‐PZ34‐PT26) with pure perovskite phase were synthesized using conventional ceramic processing via a B‐site oxide mixing route for applications in high‐temperature high‐power‐density electrotransducers and high‐temperature capacitors. The relaxor behavior is confirmed by studying the frequency and temperature dependence of the dielectric response and polarization relaxation. The ceramics exhibit a large room‐temperature dielectric constant of ∼1540 and the dielectric constant is nearly independent of frequency with a temperature gradient of ∂ε/∂T = 5.2/°C in the low‐temperature region 250 K < T < 400 K. A strong frequency dependency and abnormal increase of dielectric constant are observed at temperatures around and below Tm, which is considered to be correlated with the phase transition from tetragonal ferroelectric phase to cubic paraelectric phase confirmed by high‐temperature X‐ray diffraction measurements. The diffused dielectric behavior arises mainly from the compositional fluctuation and/or the substitutional disorder in the arrangement of cations in the perovskite crystallographic sites. The frequency‐dependent remanent polarization scales well with the existing models of random field states, which indicates that the relaxor behavior correlates with the creation of chemical heterogeneity caused by localized cationic ordering. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nanobelts and nanocones of spinel Zn2SnO4
Authors: Li Y. , Ma X. L. 
Published: January 2005

AbstractOne‐dimensional nanostructures of ternary oxide spinel, Zn2SnO4, have been prepared for the first time on a large scale via a reaction between element Sn, ZnS and Fe(NO)3 at 1350 °C in a high‐temperature tube furnace. Scanning and transmission electron microscopic observations have confirmed that the as‐synthesized products consist of belt‐like and cone‐like single crystals. The dimensions of each nanobelt range from several hundred micrometers long, 100–500 nm wide, and several tens of nanometers thick. Formation mechanisms of these 1D nanostructures have been proposed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Studies of electronic excitations in MgMoO4, CaMoO4 and CdMoO4 crystals using VUV synchrotron radiation
Authors: Mikhailik V. B. , Kraus H. , Wahl D. , Mykhaylyk M. S. 
Published: January 2005

AbstractReflection, emission and luminescence spectra of Czochralski grown molybdate crystals, i.e. MgMoO4, CaMoO4 and CdMoO4 have been investigated over a 8–295 K temperature range using VUV synchrotron radiation. Preliminary interpretation of the spectroscopic properties has been carried out on the basis of present knowledge of the electronic structure and emission properties of these materials. The results of this study support the conclusion that molybdate crystals have good prospect for application in the search for rare events as cryogenic phonon‐scintillation detectors. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quadrupole moments of the alkali dimers, Li2, Na2, and K2
Authors: Harrison James F. , Lawson Daniel B. 
Published: January 2005

AbstractThe quadrupole moments (Θ) of Li2, Na2, and K2 have been determined using SCF, B3LYP, and CCSD(T). Included in this study is the effect of valence and core–valence correlation. The variation of Θ as a function of bond length has also been evaluated from which vibrational contributions have been determined. Additionally, the shape and relative magnitude of Θ vs. bond length are attributed to the s–s nature of the bonding. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Ab initio study of the insertion reactions of Sc+(1D) with HF, HCl, H2O, H2S, NH3, PH3, CH4, and SiH4
Authors: Ye Song , Wang Chaojie 
Published: January 2005

AbstractThe mechanism of scandium cation Sc+(1D) insertion into HF, HCl, H2O, H2S, NH3, PH3, CH4, and SiH4 has been investigated by ab initio molecular theory. All these reactions involve the initial formation of intermediate complexes followed by an H‐atom migration process via a transition state to insertion products. The Sc+(1D) insertion into eight compound reactions indicate that (i) the reaction with hydride of the right‐hand group is more exothermic than that of the left‐hand group and has a lower barrier, and (ii) the reaction with the second‐row hydride has a lower overall barrier and is less exothermic than with the first‐row hydride. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Theoretical investigation of the mechanism of the intermolecular proton transfer in carbanion [1.1]ferrocenophane
Authors: Broo Anders 
Published: January 2005

AbstractDensity Functional Theory calculations, with the hybrid functional denoted B3LYP, were used to study of the intramolecular proton transfer in lithium‐reacted [1.1]ferrocenophane (FCP). Geometries of ferrocene (FC) and several FCP complexes, including dimethylated FCP and lithium‐reacted FCP, were fully optimized utilizing the B3LYP and the INDO/1 methods. The B3LYP geometries agree very well with the available experimental geometries. The INDO/1 geometries agree less well but yield reasonable geometries for FC and the FCPs considered in this work. Transition state theory (TST) was used to calculate the intramolecular proton transfer rate in FCP−. Nuclear tunneling along the reaction coordinate was considered by the Wigner correction to the TST rate constant. Nuclear tunneling appears to be very important for the proton transfer. The calculated proton transfer rate at T = 298 K, kpt(298) is 98,690 s−1 and kpt(194) is 2 s−1 compared to the observed rate in tetrahydrofuran solution kobs(298) = 32,000 s−1 and kobs(194) = 63 s−1. A slightly different mechanism than the one previously suggested is proposed based on these calculations. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Computer‐aided design of a novel ligand for retinoic acid receptor in cancer chemotherapy
Authors: Silva Carlos H. T. P. , Leopoldino Andreia M. , Silva Eloiza H. T. , Espinoza V. A. A. , Taft C. A. 
Published: January 2005

AbstractThe isotypes of RAR and RXR are retinoic acid and retinoid X acid receptors, respectively, whose ligand‐binding domain contains the ligand‐dependent activation function, with distinct pharmacological targets for retinoids, involved in the treatment of various cancers and skin diseases. Due to the major challenge which cancer treatment and cure still imposes after many decades to the international scientific community, there is actually considerable interest in new ligands with increased bioactivity. We have focused on the retinoid acid receptor, which is considered an interesting target for drug design. In this work, we carried out density functional geometry optimizations and different docking procedures. We performed screening in a large database (hundreds of thousands of molecules which we optimized at the AM1 level) yielding a set of potential bioactive ligands. A new ligand was selected and optimized at the B3LYP/6‐31G* level. A flexible docking program was used to investigate the interactions between the receptor and the new ligand. The result of this work is compared with several crystallographic ligands of RAR. Our theoretically more bioactive new ligand indicates stronger and more hydrogen bonds as well as hydrophobic interactions with the receptor. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Atmospheric‐pressure laser ionization: a novel ionization method for liquid chromatography/mass spectrometry
Authors: Constapel M. , Schellenträger M. , Schmitz O. J. , Gäb S. , Brockmann K. J. , Giese R. , Benter Th. 
Published: January 2005

AbstractWe report on the development of a new laser‐ionization (LI) source operating at atmospheric pressure (AP) for liquid chromatography/mass spectrometry (LC/MS) applications. APLI is introduced as a powerful addition to existing AP ionization techniques, in particular atmospheric‐pressure chemical ionization (APCI), electrospray ionization (ESI), and atmospheric pressure photoionization (APPI). Replacing the one‐step VUV approach in APPI with step‐wise two‐photon ionization strongly enhances the selectivity of the ionization process. Furthermore, the photon flux during an ionization event is drastically increased over that of APPI, leading to very low detection limits. In addition, the APLI mechanism generally operates primarily directly on the analyte. This allows for very efficient ionization even of non‐polar compounds such as polycyclic aromatic hydrocarbons (PAHs). The APLI source was characterized with a MicroMass Q‐Tof Ultima II analyzer. Both the effluent of an HPLC column containing a number of PAHs (benzo[a]pyrene, fluoranthene, anthracene, fluorene) and samples from direct syringe injection were analyzed with respect to selectivity and sensitivity of the overall system. The liquid phase was vaporized by a conventional APCI inlet (AP probe) with the corona needle removed. Ionization was performed through selective resonance‐enhanced multi‐photon ionization schemes using a high‐repetition‐rate fixed‐frequency excimer laser operating at 248 nm. Detection limits well within the low‐fmol regime are readily obtained for various aromatic hydrocarbons that exhibit long‐lived electronic states at the energy level of the first photon. Only molecular ions are generated at the low laser fluxes employed (∼1 MW/cm2). The design and performance of the laser‐ionization source are presented along with results of the analysis of aromatic hydrocarbons. Copyright © 2005 John Wiley & Sons, Ltd.
Stable isotopically labeled internal standards in quantitative bioanalysis using liquid chromatography/mass spectrometry: necessity or not?
Authors: Stokvis Ellen , Rosing Hilde , Beijnen Jos H. 
Published: January 2005

AbstractIt appears to be a general belief that stable isotopically labeled (SIL) internal standards yield better assay performance results for quantitative bioanalytical liquid chromatography/mass spectrometry (LC/MS) assays than does any other internal standard. In this article we describe our experiences with structural analogues and SIL internal standards and their merits and demerits. SIL internal standards are the first choice, but deuterium‐labeled compounds may demonstrate unexpected behavior, such as different retention times or recoveries, than the analyte. In addition, a SIL internal standard with identical chemical properties as the analyte may cover up assay problems with stability, recovery, and ion suppression. Since SIL internal standards are not always available or are very expensive, structural analogues can be used, however, with consideration of several issues, which are usually displayed during method validation. Copyright © 2005 John Wiley & Sons, Ltd.
An automated system for stable isotope and concentration analyses of CO2 from small atmospheric samples
Authors: Schauer Andrew J. , Lott Michael J. , Cook Craig S. , Ehleringer James R. 
Published: January 2005

AbstractWe have developed an automated, continuous‐flow isotope ratio mass spectrometry (CF‐IRMS) system for the analysis of δ13C, δ18O, and CO2 concentration (μmol mol−1) ([CO2]) from 2 mL of atmospheric air. Two replicate 1 mL aliquots of atmospheric air are sequentially sampled from fifteen 100 mL flasks. The atmospheric sample is inserted into a helium stream and sent through a gas chromatograph for separation of the gases and subsequent IRMS analysis. Two δ13C and δ18O standards and five [CO2] standards are run with each set of fifteen samples. We obtained a precision of 0.06‰, 0.11‰, and 0.48 μmol mol−1 for δ13C, δ18O, and [CO2], respectively, by analyzing fifty 100 mL samples filled from five cylinders with a [CO2] range of 275 μmol mol−1. Accuracy was determined by comparison with established methods (dual‐inlet IRMS, and nondispersive infrared gas analysis) and found to have a mean offset of 0.00‰, −0.09‰, and −0.26 μmol mol−1 for δ13C and δ18O, and [CO2], respectively. Copyright © 2005 John Wiley & Sons, Ltd.
Determination of pharmaceutical compounds in aqueous dimethyl sulfoxide by electrospray ionization mass spectrometry
Authors: Borges Virginia , Henion Jack 
Published: January 2005

AbstractStandard solutions of reserpine, dextromethorphan, imipramine and amitriptyline in dimethyl sulfoxide (DMSO), DMSO containing 0.1% formic acid, and DMSO/H2O (1:1, v/v) containing 0.1% formic acid were analyzed by positive electrospray ionization mass spectrometry (ESI‐MS). A triple‐quadrupole mass spectrometer equipped with a TurboIonspray (TIS) interface was used for the ESI‐MS analyses. The samples dissolved in the respective DMSO solution were infused directly into the mass spectrometer at 10 μL/min using an infusion pump. The positive Q1 full‐scan (m/z 50–650) mass spectrum of DMSO (MW = 78) showed three main peaks at m/z 79, 101 and 179, corresponding to the protonated molecule [DMSO+H]+, and the sodiated adducts [DMSO+Na]+ and [2DMSO+Na]+, respectively. The ESI of the compounds in DMSO and DMSO containing 0.1% formic acid was promoted by using the TIS gas (GS2) combined with the nebulizer gas (GS1), and TIS source temperature set to 250°C. In contrast, samples dissolved in DMSO/H2O (1:1, v/v) containing 0.1% formic were sprayed at a lower temperature (100°C) using only the nebulizer gas. The TIS voltage (V) was optimized in order to establish the lowest voltage necessary to achieve optimum ESI of each pharmaceutical compound with the voltage maintained below the onset potential required to produce a corona discharge at the TIS probe (sprayer). Detection limits of 10 ng/mL were achieved for reserpine, dextromethorphan, imipramine and amitriptyline in each solvent composition. Copyright © 2005 John Wiley & Sons, Ltd.