bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrophilic sponges based on 2‐hydroxyethyl methacrylate. I. effect of monomer mixture composition on the pore size
Authors: Chirila Traian V. , Chen Yi‐Chi , Griffin Brendon J. , Constable Ian J. 
Published: April 2007

AbstractA large number of hydrophilic sponges were prepared by polymerisation of 2‐hydroxyethyl methacrylate in variable concentrations of water (60‐90% wt) in the initial monomer mixture. Concentration and type of crosslinking agents (ethylene dimethacrylate (EDMA) and hexamethylene dimethacrylate (HDMA)) and concentration of redox initiators were also changed. All sponges were examined in cross‐section by conventional and environmental scanning electron microscopy. Micrographs indicated that, in order to obtain sponges with characteristics appropriate for biomedical use (e.g. pores larger than 10 μm), the minimum water concentration was 75% wt with EDMA as a crosslinking agent, or 70% wt with HDMA, for contents of crosslinking agents and initiator less than 1% wt. Micrographs also showed that higher contents of crosslinking agents or initiator led to larger pores. In high concentrations of water, this effect was less evident. Microscopic details confirmed the crucial role of the phase separation during polymerisation.
Phase equilibria of quasi‐ternary systems consisting of multicomponent polymers 1 and 2 in a single solvent. II. Cloud point curve
Authors: Shirataki Hironobu , Kamide Kenji 
Published: April 2007

AbstractTheoretical equations and a calculation method giving cloud point curve (CPC) for a multicomponent polymer 1/multicomponent polymer 2/single solvent system (i.e. quasi‐ternary system) were derived on the basis of the Flory‐Huggins solution theory. The systematic calculations based on this method were carried out to examine the effects on CPC of the type of molecular weight distribution, the polydispersity and the weight‐average degree of polymerisation of the two original polymers, and three thermodynamic interaction parameters between solvent‐polymer 1 (X01), solvent‐polymer 2 (X02) and polymer 1‐polymer 2 (X12). The shape of CPC sensitively depends on the polydispersity of the original polymer and, with an increase in polydispersity, the immiscibility region becomes wider.
Kinetics of phase transition in lyotropic liquid crystalline polymers
Authors: Lin Jiaping , Wu Herong , Li Shijin 
Published: April 2007

AbstractA kinetic study on phase transitions from nematic mesophase to isotropic state for poly(p‐benzamide) (PBA)/H2SO4 and poly(p‐phenyleneterephthalamide) (PPTA)/H2SO4 systems was carried out by using depolarized light intensity (DLI) technique and polarised light microscopy (PLM) observation. The order of phase transition and activation energy were evaluated. The results indicated that the phase transition for both PBA/H2SO4 and PPTA/H2SO4 systems is a first‐order transition, and the polymer concentration and molecular flexibility have significant influence on the activation energy of the phase transition. The influences of concentration and molecular flexibility were discussed on the basis of the modified mean‐field theory.
Copolymerisation of multimethacrylate with acrylic acid
Authors: Jantas Roman 
Published: April 2007

AbstractThe structure of products resulting from the free radical copolymerisation of multimethacrylate—poly(vinyl methacrylate)—with acrylic acid was examined by the radiometric method. The copolymerisation was carried out in dilute solutions of N,N‐dimethylformamide using 2,2′‐azobisisobutyronitrile labelled with 14C as initiator. The results show that over 90% of methacrylate units react along the template chain forming ladder‐type blocks, while the remaining units branch or do not participate in the process.
The migration of plasticizer in solid propellant grains
Authors: Venkatesan D. , Srinivasan M. , Reddy K. Audisesha , Pendse V. V. 
Published: April 2007

AbstractThe migration of the plasticizer, dioctyl adipate (DOA) in the accelerated ageing of composite propellant has been studied. The method is based on the extraction of DOA with carbon tetrachloride and its estimation by gas chromatography. The concentration of DOA in the propellant at different distances from the insulation was determined after a definite ageing period and compared with the initial DOA concentration. The effect of (a) the ageing period, and (b) the ageing temperature on the degree of migration was examined. The present studies confirm the existence of plasticizer migration in the propellant adjacent to the insulation, during ageing.
Polyaniline dispersions. 3. Influence of the polymerization conditions
Authors: Stejskal Jaroslav , Kratochvil Pavel , Gospodinova Natalia , Terlemezyan Levon , Mokreva Pavlina 
Published: April 2007

AbstractSeveral series of polyaniline dispersions were prepared by oxidative polymerization of aniline in aqueous medium. Ammonium persulfate was used as an oxidizing agent and poly(vinyl alcohol) as a steric stabilizer of dispersions. The amount of dispersion particles their size and uniformity and the fraction of the steric stabilizer attached to the particles were determined in dependence on the concentration of the individual components and on temperature. The properties of resulting dispersions are controlled mainly by the concentration of the oxidizing agent and by the polyaniline/stabilizer ratio.
Acyclic diene metathesis polymerization: The synthesis of unsaturated polyketones
Authors: Wagener K. B. , Patton J. T. , Forbes M. D. E. , Myers T. L. , Maynard H. D. 
Published: April 2007

AbstractThe first acyclic diene metathesis (ADMET) polymerization of unsaturated ketone containing monomers using the molybdenum catalyst, Mo(CHCMe2Ph)(N‐2,6‐C6H3‐i‐Pr2)[OCCH3(CF3)2]2 is reported. 6,6,8,8‐Tetramethyl‐1,12‐tridecadiene‐7‐one undergoes homopolymerization; copoly‐merizations are carried out with 1,9‐decadiene and 2,12‐dimethyl‐2,12‐dipentenylcyclododecan‐1‐one, 2,12‐diallylcyclododecan‐1‐one, and trans‐2,12‐diallyl‐2,12‐dimethylcyclododecan‐1‐one These polymerizations are initiated under bulk conditions and are continued in solution. No evidence of Wittig chemistry is observed between the carbonyl functional group and the catalyst when a high degree of steric hindrance exists around the carbonyl moiety. Polymer structures were characterized by IR, 1H NMR, and 13C NMR spectroscopy. Molecular weights were determined by endgroup analysis and gel permeation chromatography.
Cationic polymerization of 3,6‐ dibromo‐9(2,3‐epoxypropyl) carbazole in the presence of allyl alcohol or acrylic acid
Authors: Gražulevičius Juozas V. , Kavaliūnas Rimtautas , Kreivéniené Nijolé , Kublickas Rimantas 
Published: April 2007

AbstractPolymerization of 3,6‐dibromo‐9‐(2,3‐epoxypropyl) carbazole with SnCl4 in the presence of allyl alcohol or acrylic acid has been studied. This reaction has proved to be a convenient method of obtaining macromonomers containing allyl or acrylic functional groups. It was shown that both in the presence of allyl alcohol and acrylic acid polymerization proceeds by an activated monomer mechanism. Allyl alcohol and acrylic acid at the initial stage of reaction play the role of starting proton donor compound. However in contrast to allyl alcohol, acrylic acid is not totally consumed. Peculiarities of the mechanism of propagation are discussed.
The solid–liquid interface energy of organic crystals
Authors: Lu H.M. , Wen Z. , Jiang Q. 
Published: April 2007

AbstractA simple thermodynamic model, originally developed for metals based on the Gibbs–Thomson equation and related considerations for homogeneous nucleation, has been extended to predict the solid–liquid interface energy γsl of organic crystals. The model predictions correspond to available experimental and other theoretical results for 38 organic crystals. Copyright © 2007 John Wiley & Sons, Ltd.
The relative importance of specific risk factors for insomnia in women treated for early‐stage breast cancer
Authors: Bardwell Wayne A. , Profant Judith , Casden Danielle R. , Dimsdale Joel E. , Ancoli‐Israel Sonia , Natarajan Loki , Rock Cheryl L. , Pierce John P. ,   for the Women's Healthy Eating & Living (WHEL) Study Group
Published: April 2007

AbstractBackground: Many individual risk factors for insomnia have been identified for women with a history of breast cancer. We assessed the relative importance of a wide range of risk factors for insomnia in this population.Methods: Two thousand six hundred and forty‐five women ⩽4 years post‐treatment for Stage I (⩾1 cm)–IIIA breast cancer provided data on cancer‐related variables, personal characteristics, health behaviors, physical health/symptoms, psychosocial variables, and the Women's Health Initiative‐Insomnia Rating Scale (WHI‐IRS; scores ⩾9 indicate clinically significant insomnia).Results: Thirty‐nine per cent had elevated WHI‐IRS scores. In binary logistic regression, the variance in high/low insomnia group status accounted for by each risk factor category was: cancer‐specific variables, 0.4% (n.s.); personal characteristics, 0.9% (n.s.); health behaviors, 0.6% (n.s.); physical health/symptoms, 13.4% (p<0.001); and, psychosocial factors, 11.4% (p<0.001). Insomnia was associated with worse depressive (OR = 1.32) and vasomotor symptoms (particularly night sweats) (OR = 1.57).Conclusion: Various cancer‐specific, demographic, health behavior, physical health, and psychosocial factors have been previously reported as risk factors for insomnia in breast cancer. In our study (which was powered for simultaneous examination of a variety of variables), cancer‐specific, health behavior, and other patient variables were not significant risk factors when in the presence of physical health and psychosocial variables. Only worse depressive and vasomotor symptoms were meaningful predictors. Copyright © 2007 John Wiley & Sons, Ltd.
Incapacity or unemployment? The utility of an administrative data source as an updatable indicator of population health
Authors: Norman Paul , Bambra Clare 
Published: April 2007

AbstractA lack of annually accessible morbidity information for small geographical areas in England and Wales means that health studies are often restricted to using decennial, self‐reported census measures. Administrative data on health‐related benefit claims, in the form of Incapacity Benefit (IB) data, are more regularly available and claimants are professionally diagnosed. This source may have the potential to be an annual indicator of population health. We examine IB as an indicator of population health at local government district and subdistrict levels by investigating distributions and relationships between IB and other health measures from the census and from mortality statistics. We found that relationships in 2001 between IB, census measures and mortality suggest that using IB as an indicator of population health will give very similar results, especially with those reporting themselves in the 2001 Census as ‘permanently sick or disabled’ and in the more urban areas. Although IB should be an objective measure as it is professionally diagnosed, we recognise that IB may hide unemployment and have inferred an estimate using census data on economic activity by exploring the relationship between IB and those reporting themselves permanently sick or disabled. This estimate suggests that previous assertions about the relationship between IB and unemployment may have been overzealous. On balance, IB is currently a useful indicator of relative health for small areas. Copyright © 2007 John Wiley & Sons, Ltd.
Effects on transition temperature and Raman spectra of substitution of Cr and Al for Mg in MgB2
Authors: Shi Lei , Zhang Huarong , Zhou Shiming , Jia Yunbo , Chen Lin 
Published: April 2007

AbstractMg1−x Mx B2 (M = Cr, Al) polycrystalline bulk samples with 0 ≤ x ≤ 5% have been synthesized by a solid state reaction and studied by X‐ray diffraction, SEM and Raman spectroscopy. By comparing with the results of Sc‐substituted MgB2, it is found that all these atomic substitutions for Mg depress Tc, and Cr and Sc substitutions depress Tc even more quickly than the one of Al doping. It is suggested that the Tc changes of the M‐substituted MgB2 can be understood by the competing/cooperating effects of the hole‐filling and the disorder. The Raman peak linewidth decreases for Al‐substituted MgB2, which represents an opposite trend to the linewidth change of Mg1−x Crx B2 and shows an evidence of the disorder caused by the atomic substitution and the different arrangement of the substituted atoms in the lattice. Meanwhile, different frequency changes of the Raman peak for the Cr‐ and Al‐substitute MgB2 are discovered and understood by the competing/cooperating effects of the electron‐phonon coupling, the grain size, and the lattice contraction. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of simultaneous substitution of Li+ and Ti4+ in ceramics of Pb2KNb5O15 on structure, dielectric, modulus, impedance and conductivity properties
Authors: Sambasiva Rao K. , Murali Krishna P. , Madhava Prasad D. 
Published: April 2007

AbstractLead potassium lithium titanium niobate, Pb0.8K0.2Li0.2Ti0.25Nb1.8O6 (PKLTN) is prepared through a solid‐state reaction route. The XRD analysis at room temperature indexed as single phase with orthorhombic tungsten bronze (TB) with completely filled (A6C4B10O30‐type) structure. Partial substitution of Ti4+ in Nb5+ increased the B sites ordering, and is associated in charge compensation, creating oxygen vacancies entering in the crystal structure described by Kroger–Vink notation. Simultaneous substitution of Li+ and Ti4+ in Pb2KNb5O15 (PKN) resulted in an increase in the lattice parameters (a = 18.0131 Å, b = 18.1520 Å and c = 3.9376 Å) and a decreased TC to 445 °C. Space‐charge polarization, relaxation phenomenon and conduction mechanism due to charge carriers have been analyzed using dielectric, impedance and modulus characterization. Cole–Cole plots showed non‐Debye (polydispersive) type relaxation. DC conductivity activation energies calculated from Rb, MII peak frequencies and thermal behavior of AC and DC conductivity at 1 kHz in the ferro region are comparable to 0.32 eV, reveals the ionic conduction mechanism in PKLTN. Conduction via a hopping mechanism has been established from Jonscher's power law, σ (ω) = σDC + Aωn. The stretched exponential parameter, β is a measure of the distribution of relaxation times and was computed as a function of temperature (360–595 °C) using an impedance formalism, and has a minimum value of 0.74 at TC. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wave propagation in functionally graded piezoelectric spherically curved plates
Authors: Jiangong Yu , Bin Wu , Hongli Huo , Cunfu He 
Published: April 2007

AbstractBased on linear three‐dimensional piezoelasticity, a Legendre orthogonal polynomial series expansion approach is used for determining the characteristics of guided waves in continuous functionally graded piezoelectric materials (FGPM) as spherically curved plates. The displacement components and electric potential, expanded in a series of Legendre polynomials, are introduced into the governing equations along with position‐dependent material constants so that the solution of the wave equation is reduced to an eigenvalue problem. Our results from a homogeneous anisotropic spherically curved plate are compared with those published earlier to confirm the accuracy and range of applicability of this polynomial approach. Guided‐wave dispersion curves for FGPM and the corresponding FGM spherically curved plates are calculated and the effect of piezoelectricity is shown. The mechanical displacement distribution and electric potential distribution are also illustrated. Finally, the influence of the ratio of radius to thickness on the dispersion curves is discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Superconductivity in the two‐dimensional Hubbard model?
Authors: Baeriswyl D. , Eichenberger D. , Gut B. 
Published: April 2007

AbstractA refined variational wave function for the two‐dimensional repulsive Hubbard model is studied numerically, with the aim of approaching the difficult crossover regime of intermediate values of U. The issue of a superconducting ground state with d‐wave symmetry is investigated for an average electron density n ≈ 0.8 and for U = 8t. Due to finite‐size effects a clear‐cut answer to this fundamental question has not yet been reached. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gaped graphene bilayer: disorder and magnetic field effects
Authors: Castro Eduardo V. , Peres N. M. R. , Lopes dos Santos J. M. B. 
Published: April 2007

AbstractDouble layer graphene is a gapless semiconductor which develops a finite gap when the layers are placed at different electrostatic potentials. We study, within the tight‐biding approximation, the electronic properties of the gaped graphene bilayer in the presence of disorder and perpendicular magnetic field. We show that the gap is rather stable in the presence of diagonal disorder. We compute the cyclotron effective mass in the semi‐classical approximation, valid at low magnetic fields. Landau level formation is clearly seen in zigzag and armchair ribbons of the gaped bilayer at intermediate magnetic fields. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of doping on the pseudogap enhancement due to magnetic impurities in d‐density waves
Authors: Dóra Balázs , Maki Kazumi , Virosztek Attila , Ványolos András 
Published: April 2007

AbstractWe study the effect of quantum magnetic impurities on d‐wave spin density waves (d‐SDW). The impurity spins are aligned coherently according to the spin space anisotropy of the condensate. Both the order parameter and transition temperature increases due to the coherent interplay between magnetic scatterers and d‐SDW at fixed doping. By increasing the doping, the d‐SDW collapses. This can explain the recent experimental data on the pseudogap enhancement of Ni substituted NdBa2{Cu1−y Niy }O6.8 from Pimenov et al. [Phys. Rev. Lett. 94, 227003 (2005)]. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Enhancement of thermoelectric performance in strongly correlated multilayered nanostructures
Authors: Freericks J. K. , Zlatić V. 
Published: April 2007

AbstractWe illustrate how the electronic charge reconstruction near the interfaces of metal–strongly‐correlated‐barrier–metal devices can lead to a significant enhancement of the thermoelectric response due to the breaking of particle‐hole symmetry. We show how one can achieve effective Seebeck coefficients larger than 150 µV/K and effective electronic figures‐of‐merit ZT higher than 1. Our work shows that electronic thermoelectric transport properties can be significantly enhanced from inhomogeneities created by the rearrangement of charge near the interfaces, and that bulk figures‐of‐merit cannot generically be employed to determine the figure‐of‐merit of a multilayered nanostructure. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Performance evaluation of elemental analysis/isotope ratio mass spectrometry methods for the determination of the D/H ratio in tetramethylurea and other compounds – results of a laboratory inter‐comparison
Authors: Bréas Olivier , Thomas Freddy , Zeleny Reinhard , Calderone Giovanni , Jamin Eric , Guillou Claude 
Published: April 2007

AbstractTetramethylurea (TMU) with a certified D/H ratio is the internal standard for Site‐specific Natural Isotope Fractionation measured by Nuclear Magnetic Resonance (SNIF‐NMR®) analysis of wine ethanol for detection of possible adulterations (Commission Regulation 2676/90). A new batch of a TMU certified reference material (CRM) is currently being prepared. Whereas SNIF‐NMR® has been employed up to now, Elemental Analysis/Isotope Ratio Mass Spectrometry (2H‐EA‐IRMS) was envisaged as the method of choice for value assignment of the new CRM, as more precise (better repeatable) data might be obtained, resulting in lower uncertainty of the certified value. In order to evaluate the accuracy and intra‐ and inter‐laboratory reproducibility of 2H‐EA‐IRMS methods, a laboratory inter‐comparison was carried out by analysing TMU and other organic compounds, as well as some waters. The results revealed that experienced laboratories are capable of generating robust and well comparable data, which highlights the emerging potential of IRMS in food authenticity testing. However, a systematic bias between IRMS and SNIF‐NMR® reference data was observed for TMU; this lack of data consistency rules out the 2H‐IRMS technique for the characterisation measurement of the new TMU CRM. Copyright © 2007 John Wiley & Sons, Ltd.
Structured analysis of piecewise‐linear interconnected systems
Authors: Fowler Jeffrey M. , D'Andrea Raffaello 
Published: April 2007

AbstractThis paper considers the problem of assessing the induced L2gain of a system composed of non‐identical interconnected piecewise‐linear subsystems, when the topology of the underlying graph is arbitrary. Blending tools inspired by dissipativity theory and theS‐procedure, it presents sufficient conditions in the form of a set of finite‐dimensional linear matrix inequalities which are coupled in a way that reflects the spatial structure of the system under analysis. Results are presented comparing the efficacy of the new conditions to similar conditions for an equivalent global piecewise‐linear system. Copyright © 2007 John Wiley & Sons, Ltd.
Decentralized redistribution for cooperative patrol
Authors: Moore Brandon J. , Passino Kevin M. 
Published: April 2007

AbstractThis paper addresses the problem of enabling a group of autonomous vehicles to effectively patrol an environment significantly larger than their communication and sensing radii. Our formulation uses ana priorispatial decomposition of the environment into smaller areas in order to provide a framework for the allocation of vehicles to different parts of the environment. We develop a distributed cooperative control algorithm that transfers vehicles between these areas based on only local information and prove that it achieves the proper environment‐wide distribution of vehicles within a finite time interval. Various applications are discussed and simulations are included to illustrate convergence dynamics as well as to quantify practical performance as a function of problem parameters. Copyright © 2007 John Wiley & Sons, Ltd.
From teachers to testers: How parents talk to novice and expert children in a natural history museum
Authors: Palmquist Sasha , Crowley Kevin 
Published: April 2007

AbstractInformed by literature on childhood expertise in high‐interest topics and parent–child conversation in museum settings, this study explored how children's level of dinosaur expertise influences family learning opportunities in a natural history museum. Interviews identified children with high and low dinosaur knowledge and assigned them to expert and novice groups. Parent surveys revealed that expert children were more likely to have home environments where family members shared interests in dinosaurs and provided a variety of dinosaur learning resources. Analysis of family conversations demonstrated that parents with novice children more actively engaged them in learning conversations than parents with expert children. The implications of this shift in parental engagement are considered in terms of interest and knowledge development in informal settings, highlighting how islands of expertise might facilitate and in some cases hinder learning through shared family activity. © 2007 Wiley Periodicals, Inc. Sci Ed 91:783–804, 2007
Recent results on the use of model resolution functions for the deconvolution of depth profiling data
Authors: Kotz Samuel , Nadarajah Saralees 
Published: April 2007

AbstractThe paper by Markarov [Surface and Interface Analysis, 20, 1993, pp. 821–826] considered the important problem of deconvolution of depth profiling data. In this note, we consider the problem of convoluting the initial Gaussian profile with a double exponential resolution function. The paper by Markarov only provided an asymptotic treatment of this problem. Here, we provide exact results, various approximations as well as a simple computer program. Copyright © 2007 John Wiley & Sons, Ltd.