bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phantom‐based evaluation of geometric distortions in functional magnetic resonance and diffusion tensor imaging
Authors: Mattila Seppo , Renvall Ville , Hiltunen Jaana , Kirven Douglas , Sepponen Raimo , Hari Riitta , Tarkiainen Antti 
Published: March 2007

AbstractPhantom‐based evaluation of geometric distortions in functional MRI and diffusion tensor imaging (DTI) was investigated. An acrylic water‐filled phantom with a grid structure was designed and manufactured to provide accurate geometric information over the volume measured in human brain imaging. The grid structures were well detected in data acquired using a 3‐T MRI scanner with echo‐planar imaging (EPI) sequences commonly applied in functional MRI and DTI. A method for quantifying distortions in the phantom data was presented and applied for the images. The validity of the phantom for EPI was evaluated by quantitatively comparing the distortions present in and induced by the phantom and a human brain when imaged under identical conditions. The results suggest that the new phantom can reveal geometric distortions easily undermined by standard MRI phantoms. For example, prominent variability in the distortions was found as a function of the orientation of the diffusion‐sensitizing gradient. Possible future applications for this type of phantom include quality assurance and calibration of the hardware and software used in EPI‐based functional MRI and DTI. Magn Reson Med 57:754–763, 2007. © 2007 Wiley‐Liss, Inc.
A branch‐and‐regret heuristic for stochastic and dynamic vehicle routing problems
Authors: Hvattum Lars Magnus , Løkketangen Arne , Laporte Gilbert 
Published: March 2007

AbstractThis paper describes a new Branch‐and‐Regret Heuristic for a class of dynamic and stochastic vehicle routing problems. This work is motivated by a real‐life problem faced by a major transporter in Norway. The heuristic uses stochastic information during the solution process. The new method is shown to be superior to previous heuristics that are uniquely based on a pure dynamic approach. The proposed heuristic is well suited to problems containing stochastic customers, stochastic demands, or both. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 49(4), 330–340 2007
A linearly conforming point interpolation method (LC‐PIM) for three‐dimensional elasticity problems
Authors: Zhang G. Y. , Liu G. R. , Wang Y. Y. , Huang H. T. , Zhong Z. H. , Li G. Y. , Han X. 
Published: March 2007

AbstractLinearly conforming point interpolation method (LC‐PIM) is formulated for three‐dimensional elasticity problems. In this method, shape functions are generated using point interpolation method by adopting polynomial basis functions and local supporting nodes are selected based on the background cells. The shape functions so constructed have the Kronecker delta functions property and it allows straightforward imposition of point essential boundary conditions. Galerkin weak form is used for creating discretized system equations, and a nodal integration scheme with strain‐smoothing operation is used to perform the numerical integration. The present LC‐PIM can guarantee linear exactness and monotonic convergence for the numerical results. Numerical examples are used to examine the present method in terms of accuracy, convergence, and efficiency. Compared with the finite element method using linear elements, the LC‐PIM can achieve better efficiency, and higher accuracy especially for stresses. Copyright © 2007 John Wiley & Sons, Ltd.
Evaluating adverse events after vaccination in the Medicare population
Authors: Burwen Dale R. , La Voie Lawrence , Braun M. Miles , Houck Peter , Ball Robert 
Published: March 2007

AbstractPurposePost‐licensure observational studies using large linked databases can provide important data about whether adverse events are associated with vaccines, but databases that have been used may not have sufficient statistical power to examine rare events, and may underrepresent the elderly. We assessed the utility of Medicare data for evaluating adverse events after influenza and pneumococcal vaccines, by using an example involving selected clinical conditions, and evaluating aspects of data quality relevant to vaccine safety analyses.MethodsWe used 2001 data from the National Claims History File and Enrollment Database to determine if hospitalization for urinary tract infection (not likely associated with vaccination) or for cellulitis and abscess of the upper arm and forearm is associated with vaccination.ResultsFor influenza vaccine, the 7‐day period after vaccination did not demonstrate an elevation in hospitalization with cellulitis and abscess of the upper arm and forearm; for pneumococcal vaccine, a clear peak was evident. No increase in urinary tract infection was found after either influenza or pneumococcal vaccine. Having a prior Medicare claim for pneumococcal vaccine within 5 years was a risk factor for hospitalization with cellulitis and abscess of the upper arm and forearm (relative risk, 2.6; 95% confidence limits (CL), 1.3, 5.0).ConclusionsMedicare data are a useful source for evaluating adverse events after vaccination. Screening analyses can be performed using administrative data, but medical record review to validate diagnoses will often be needed for rigorous study of vaccine‐adverse event associations. Published in 2007 by John Wiley & Sons, Ltd.
The effect of a secondary process on the course of polymer crystallisation
Authors: Hay J. N. , Booth A. 
Published: March 2007

AbstractThe possibility that the presence of several processes occurring during the crystallisation of polymers may account for anomalous constant fractional values of the Avrami exponent is reconsidered, and for various reasons rejected. Experimental isotherms exhibit systematic variations when analysed as two stage processes, which can only be accounted for by fractional n values of no theoretical significance. An explanation for these deviations must be sought in the mechanism of spherulitic crystallisation, and in particular the mechanism of branching and impurity rejection of the basic fibrillar units.
Reaction between chlorophosphazenes and some alkyl phosphates: Formation of temperature‐stable thermosetting materials
Authors: Emblem H. G. , Fothergill E. W. 
Published: March 2007

AbstractThe reaction between chlorophosphazenes and triethyl, tri‐n‐butyl and acid ethyl phosphates has been studied as a means of preparing temperature‐stable thermosetting resinous materials. Ethyl or n‐butyl chlorides were eliminated (together with hydrogen chloride in the case of acid ethyl phosphate) and thermosetting resinous products were obtained. The products are film forming when stoved in air. Asbestos laminates, which retain up to 64% of their strength when heated to 500 °C for 50 h in air, have been made with the thermosetting resinous products obtained from the reaction between a chlorophosphazene and triethyl or tri‐n‐butyl phosphates.
The effects of pressure and temperature upon the viscosities of liquids with special reference to polymeric liquids
Authors: Cogswell F. N. , McGowan J. C. 
Published: March 2007

AbstractFrom a consideration of the work required for expansion of a liquid, the following relationship between viscosity η, pressurePand temperatureTis put forward.magnified imageFor unassociated liquids with molecules which are not too large,V* is taken as the parachor, log10(η* in Ns/m2) is −3.88,P* is 8.58 × 106N/m2,Ris the gas constant, andT* is a constant characteristic of each liquid. The equation can be applied to polymeric liquids ifV* and η* are taken as disposable constants. For example, for polystyreneV* is found to be 3 × 10−3m3mol−1and log10(η* in Ns/m2) to be 3.4 log10M̄w−10.2 whereM̄wis the weight‐average molecular weight (kg/mol) from 5 kg/mol upwards. In the equation, the same constants serve for the variation of viscosity with pressure and with temperature. The viscosity under a high pressure can therefore be estimated from viscosities all measured at normal pressures but at different temperatures. The viscosities of a number of polymers have been measured over a range of temperature and pressure and the results support the equation. Support is found for the view that segments are involved in the flow of polymeric liquids andV* gives a measure of the volume of the segment. The size of the segment seems to increase as the flexibility of the polymer chain decreases. The lowest values forV* are found for polysiloxanes in which the segment seems to be only four atoms long. Larger values ofV* are found for polymers with units of the type –CH2–CHR‐. Larger values still ofV* are given by polymers with units of the type –CH2‐CR1R2‐ and even largerV* values are found for those polymers with benzene rings constituting a major part of the main chain. AsV* rises the viscosity of the polymeric liquid becomes much more dependent upon pressure and temperature. Thus whilst the polysiloxanes have viscosities which are relatively insensitive to pressure and temperature, the aromatic polysulphones and poly(2,6‐dimethylphenylene oxide) have viscosities which are very sensitive to pressure and temperature.
Application of europium and praseodymium shift reagents to the n.m.r. spectra of polymers
Authors: Katritzky A. R. , Smith A. 
Published: March 2007

AbstractThe use of Eu(fod)3 and Pr(fod)3 shift reagents for the investigation of the nuclear magnetic resonance spectra of polymers is reported for the following samples: poly(vinyl methyl ether), poly(vinyl ethyl ether), poly(vinyl acetate) and poly‐(propylene oxide).
Principles of action of polymeric flocculants
Authors: Kitchener J. A. 
Published: March 2007

AbstractThe relationship of flocculation by water‐soluble polymers to the classical phenomena of colloid chemistry is pointed out and the contributions of electrostatic and non‐electrostatic forces are discussed.Modern flocculants have a high degree of polymerization (e.g. c. 50 000) and an extremely extended configuration when dissolved in a favourable solvent; this factor explains qualitatively some of the peculiarities of flocculation by polymers and indicates the need for rational control of their use if optimum results are to be achieved. It is concluded, however, that a quantitative theory of specific flocculant systems is not possible at present.Future developments in flocculation technology will almost certainly include introduction of cheaper or more selective flocculants, improved control through the use of auxiliary reagents and more sophisticated consideration of the surface chemistry of materials that have to be flocculated.
Modern experimental methods for the observation of the far infrared spectra of polymers
Authors: Chantry G. W. , Fleming J. W. 
Published: March 2007

AbstractThe introduction of very sensitive detectors and the use of phase modulation has enabled interferometric spectroscopy to be extended downwards in frequency until the spectral coverage overlaps that provided by microwave dielectric methods. The radiometric precision available has been steadily improved by taking advantage of both instrumental and computational advances and the accuracy which can now be attained is comparable to that of dielectric or mid‐infrared methods. Both the real and the imaginary components of the complex dielectric constant (or the complex refractive index) can now be obtained for moderately transparent materials over the millimetre and submillimetre bands for a wide range of specimen temperature, and reflectance methods have been developed for the study of heavily absorbing specimens. The far infrared band is particularly appropriate for the study of high polymers. With these instrumental innovations considerable advances may be expected in the understanding of molecular motion in these materials.
Structure and permeability of porous films of poly(hydroxy ethyl methacrylate)
Authors: Haldon R. A. , Lee B. E. 
Published: March 2007

AbstractPorous films of poly(hydroxy ethyl methacrylate) have been made by photo‐polymerisation of solutions of the monomer. The permeability of homogeneous films depends on the cross‐link density and the concentration and composition of the polymerisation solvent. A membrane of minimum water permeability, in which the transport mechanism is principally diffusion, results from a cross‐link concentration of ∼9.4 mol‐% and a monomer concentration of ∼75% in an aqueous ethylene glycol solvent (20% ethylene glycol).More porous (macroporous) films were prepared by first cooling the solution such that the solvent freezes and the monomer occupies the interstices between the solvent crystals. After polymerisation and removal of the solvent, a porous structure results. The rate of freezing, the profile of the thermal gradient, and the solvent and crosslinker concentrations control the permeability of this film. Slow cooling gives random pores (K ≃6 × 10−15 cm2), but rapid, directional cooling from one face gives oriented pores with K ≃10−12 cm2. A 6‐order change in K results from varying the monomer concentration from 40 to 85% in a 4:1 water: ethylene glycol solvent, and a 3‐order change from increasing the ethylene glycol content of the solvent from 0 to 40% at a fixed monomer concentration.
Stabilisation of polyacrylonitrile by oxidative transformation
Authors: Johnson J. W. , Potter W. , Rose P. G. , Scott G. 
Published: March 2007

AbstractThe changes occurring during the heat treatment of polyacrylonitrile polymers in the presence of air up to 350 °C have been examined using both physical and chemical techniques. It is concluded that substantial oxidation does not occur until the polymer has been converted to a ladder structure containing readily oxidisable methylene groups. The development of the highly characteristic physical behaviour of the oxidised polymer, notably absence of melting and hydrophilicity, is associated with the formation of a strongly hydrogen bonded polydihydropyrid‐4‐one structure which acts as an internal restraint to molecular motion and permits the orientation of the parent polymer to be carried through to the higher temperature pyrolysed carbon fibre.
Dielectric Properties of Styrene—Butadiene Rubber/Silicon Dioxide Mixtures
Authors: Hanna Faika F. , Yehia Abbas A. , Abou‐Bakr Abdel‐Fattah 
Published: March 2007

AbstractThe dielectric constant ϵ′ and dielectric loss ϵ″ have been investigated for SBR samples vulcanized with TMTD and loaded with silica in increasing quantities in the frequency range from 60 Hz to 108 Hz at room temperature. Also, the physico‐mechanical properties of these samples have been investigated.The results of ϵ′ and ϵ″ are analysed using the Cole—Cole method. Two absorption regions are found: a low frequency absorption region with a maximum at about 10 kHz which is attributed to Maxwell—Wagner effect and a high frequency absorption region with a maximum at 107 Hz which is due to the orientation of polar groups. A third absorption region appeared at frequencies below 100 Hz and may be due to absorption of moisture arising from the presence of silica in the sample.
Structure of the cobalt drier complex
Authors: O'Neill Leonard A. , Falla Norman A. R. 
Published: March 2007

AbstractCobalt octoate (2‐ethyl hexoate) has been studied by a wide range of spectroscopic and physical techniques and found to be polymeric. A structure for the compound is proposed. Its activity as a drier in a surface coating medium is shown to be related to its polymeric state and to the coordinating effect of other components present in the system. Auxiliary metals such as calcium or lead enhance the activity by providing a strong ligand field around the cobalt, facilitating the transition from the cobaltous to cobaltic state. Other metals such as zinc or tin, or polyols reduce the activity by coordination to configurations unfavourable to this change.
Reactions of Wheland complexes: base catalysis in re‐aromatization reaction of σ complexes obtained from 1,3,5‐tris(N,N‐dialkylamino)benzene and arenediazonium salts
Authors: Forlani Luciano , Boga Carla , Del Vecchio Erminia , Ngobo Aline‐Laure Tocke Dite , Tozzi Silvia 
Published: March 2007

AbstractThe usual idea on the two‐steps mechanism of aromatic electrophilic substitution reactions is that the first step (the attack of the electrophilic reagent on the activated substrate) is rate limiting, while the driving force of the reaction is the fast proton departure to recover the resonance energy of the aromatic substrate. The now examined systems allow the formation of stable σ cationic complexes (Wheland intermediates) which may be investigated by simple procedures. Data here reported represent a clear and simple instance of a measurement of the rate of the proton abstraction from a Wheland intermediate and they indicate that this proton abstraction occurs by base catalysis in a rate determining step. Probably, this feature is more frequent than that usually conceived in the mechanism of electrophilic aromatic substitution reactions, because these reactions are often carried out in reaction mixtures containing large amounts of proton acceptor species which might mask the possible base catalysis. Copyright © 2007 John Wiley & Sons, Ltd.
Triplet state and phenoxyl radical formation of 3, 4‐methylenedioxy phenol: a combined laser flash photolysis and pulse radiolysis study
Authors: Joshi Ravi , Kapoor S. , Mukherjee T. 
Published: March 2007

AbstractFormations of triplet state, molecular cation radical, and phenoxyl radical of 3,4‐methylenedioxy phenol (sesamol, SOH) in organic solvents have been investigated by laser photolysis as well as pulse radiolysis techniques. Photolysis of SOH in cyclohexane has been found to produce both triplet state (λmax ∼ 480 nm) and phenoxyl radical (425–430 nm) of SOH by mono‐photonic processes. However, radical cation (λmax = 450 nm) and phenoxyl radical of SOH have been observed on radiolysis in cyclohexane. Further, radiolysis of SOH in benzene has been found to produce phenoxyl radical only. Mechanism of phenoxyl radical formation by photo‐excitation of SOH has been studied and triplet energy level of SOH is estimated to lie between 1.85 and 2.64 eV. Copyright © 2007 John Wiley & Sons, Ltd.
Effect of temperature, ration, body size and age on sulphur isotope fractionation in fish
Authors: Barnes Carolyn , Jennings Simon 
Published: March 2007

AbstractSulphur isotope analysis (δ34S) is increasingly identified as a valuable tool for source differentiation and the determination of trophic level in food webs, but there are still many uncertainties associated with the interpretation of δ34S data. To investigate the effects of temperature, ration, body size and age on sulphur trophic fractionation (Δδ34S) in fish, we reared European sea bass (Dicentrarchus labrax) on identical diets at 11 and 16°C at three ration levels for over 600 days. Δδ34S was between 0 and −1‰. The effect of temperature on Δδ34S was small and inconsistent, varying over the course of the experiment and depending on ration. This contrasts with temperature effects on bass Δδ13C and Δδ15N, where Δδ13C increases at warm temperatures while Δδ15N falls. Body size and age had a positive relationship with Δδ34S but the relationship with size was not significant for bass that weighed >20 g. As Δδ34S is small and the range in δ34S of potential diet items can be much greater than the range in δ13C or δ15N, our results show that sulphur stable isotopes are particularly useful for source differentiation in fish. Copyright © 2007 John Wiley & Sons, Ltd.
Resolution of infrared matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry using glycerol; enhancement with a disperse laser beam
Authors: Cha Hyun Jung , Moon Jeong Hee , Kim Myung Soo 
Published: March 2007

AbstractSome experimental factors affecting the resolution in glycerol infrared matrix‐assisted laser desorption/ionization (IR‐MALDI) time‐of‐flight (TOF) mass spectrometry were investigated. Loading the sample inside a cavity covered with a grid was found to improve the resolving power as reported previously, although not to the extent attainable in UV‐MALDI using the same instrument. The resolving power improved as the laser spot area at the sample position got larger, becoming almost comparable with that in UV‐MALDI when the spot area was a little larger than the cavity size. Reduced concentration of the ablated materials in the acceleration region with the use of the grid and large irradiation area may be responsible for the enhanced resolution. In addition, the threshold laser fluences measured in this work were lower than those reported in the literature and tended to decrease more rapidly as the irradiation area increased than predicted previously. The implication of similar threshold fluences for matrix and analyte ions is discussed in relation to the analyte ion formation mechanism. Copyright © 2007 John Wiley & Sons, Ltd.
Erweiterung der DASt‐Richtlinie 009 für die Stahlgütewahl bei Einschubverbindungen im Hochbau
Authors: Höhler Susanne , Sedlacek Gerhard 
Published: March 2007

AbstractDie DASt‐Richtlinie 009, äquivalent mit DIN EN 1993‐1‐10, liefert ein auf der Bruchmechanik basierendes Verfahren zur Stahlgütewahl für Stahlbauten zur Vermeidung von Sprödbruch bei niedrigen Temperaturen. Dieses Verfahren ist ursprünglich für die Bedingungen des Brückenbaus, d.h. für ermüdungswirksame Belastungen abgeleitet worden und gilt für alle Kerbdetails, die in DIN EN 1993‐1‐9 oder im DIN‐Fachbericht 103 enthalten sind. Bei Anwendung solcher Kerbdetails liegt die Stahlgütewahl auch im Hochbau auf der sicheren Seite. Wirtschaftliche Hochbauverbindungen, z. B. Einschubverbindungen, beruhen auf plastischen Bemessungsmodellen und sind nicht kerbfallorientiert gestaltet. Daher fallen sie nicht in den Gültigkeitsbereich der DASt‐RiL 009.Der vorliegende Beitrag liefert einen Vorschlag für die Erweiterung der DASt‐Richtlinie 009, mit der auch für Einschubverbindungen die Stahlgütewahl durchgeführt werden kann. Dabei wird ähnlich wie im Brückenbau vorgegangen, jedoch werden die Eingangsgrößen für den bruchmechanischen Nachweis (z. B. Rißgrößen) ersetzt. Die vereinfachten Tabellen sind ähnlich gestaltet wie in der DASt‐RiL 009, allerdings haben neben der Blechdicke auch die geometrischen Parameter des Blechausschnitts einen Einfluß.
Reflection and transmission coefficients for water wave scattering by a sea‐bed with small undulation
Authors: Martha S.C. , Bora S.N. 
Published: March 2007

AbstractThe scattering of a train of progressive waves by a small undulation of the bottom of a laterally unbounded sea is considered with two dimensional linear water wave theory. Assuming irrotational motion, a simplified perturbation analysis is employed to obtain the first order corrections to the velocity potential by using the Green's integral theorem in a suitable manner and also to the reflection and transmission coefficients in terms of integrals involving the shape of the function $c(x)$ representing the bottom undulation. Two particular forms of the shape function are considered and the integrals for reflection and transmission coefficients are evaluated for these shape functions. Out of these two cases, we focus mainly on a patch of sinusoidal ripples at the bottom and find that the reflection coefficient up to the first order is an oscillatory function of β which is twice the ratio of the wave numbers of the wave and the ripple bed. When this ratio becomes 0.5, i.e., when β = 1 (the situation when Bragg resonance occurs), the reflection coefficient becomes a multiple of the number of ripples, and high reflection of the incident wave energy occurs if this number is large. We present the result in graphical form for one, two, and six ripple(s) in the patch. The results find absolute agreement with available results. We also show the graphical comparison of the reflection coefficient against the wave number for one, three, and five ripple(s).