bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vitro corrosion behaviour of Ti‐5Al‐2Nb‐1Ta alloy in Hanks solution
Authors: Tamilselvi S. , Rajendran N. 
Published: April 2007

AbstractElectrochemical polarization and impedance spectroscopic (EIS) techniques were used to investigate the corrosion behavior of Ti‐5Al‐2Nb‐1Ta alloy in Hanks solution at different immersion periods (0 h, 120 h, 240 h and 360 h). The impedance spectra are fitted using a non‐linear least square (NLLS) fitting procedure. The EIS spectra exhibited a two time constant system, suggesting the formation of two layers on the metal surface. The surface morphology of the alloy has been characterized by SEM and EDAX measurements.
Research on corrosivity of narrow distillate oil of crude oil with naphthenic acid and sulfur
Authors: Wang J.H. , Zhao W.Z. 
Published: April 2007

AbstractThe present study is focused on corrosion of crude oil containing naphthenic acid (NA) and sulfur to provide effective anticorrosion measures for the process units of oil refineries. Corrosion laws of distillate oils from crude oil with NA and sulfur can be studied through the impact of temperature, flow velocity, sulfur content, and acid value on corrosion changes of sulfur and NA before and after the experiments.
Refinement of cardiac NMR imaging in awake hamsters: proof of feasibility and characterization of cardiomyopathy
Authors: Parzy Elodie , Fromes Yves , Thiaudiere Eric , Carlier Pierre G. 
Published: April 2007

AbstractThe goal of this study was to demonstrate the feasibility of cardiac NMR imaging in conscious hamsters and its usefulness in evaluating cardiac abnormalities in a small‐animal model of cardiomyopathy. Awake hamsters, controls and cardiomyopathic ones (CHF 147), were immobilized in a dedicated holder. Half‐Fourier single‐shot FSE imaging, with outer‐volume suppression and ‘black‐blood’ contrast provided images free from motion artifact with good visualization of cardiac anatomy at any point in the cardiac cycle. Series of double‐oblique views were acquired with or without electrocardiograph gating. Image acquisition time was 55 ms, with an in‐plane resolution of 470 × 625 µm2. Left ventricular volumes, ejection fraction, and myocardium NMR signal heterogeneity were compared in CHF 147 and control hearts. Left ventricles of CHF 147 hamsters were dilated, as indicated by the increase in end‐diastolic cavity volume (299 ± 79 mm3) compared with the controls (141 ± 39 mm3; P = 0.0002). Left ventricular ejection fraction was largely reduced (45 ± 9% vs 86 ± 4%; P < 0.0001). The NMR signal distribution at an effective echo time of 41 ms was more heterogeneous in the myocardial wall of CHF 147 hamsters than in controls (1.87 ± 0.37 a.u. vs 0.98 ± 0.12 a.u., respectively; P = 0.0002). This study is a refinement of animal experimentation, as it demonstrates for the first time that characteristic features of cardiac pathology can be evaluated with ultra‐fast NMR imaging in conscious small rodents. Copyright © 2007 John Wiley & Sons, Ltd.
Finite elements with embedded strong discontinuities for the modeling of failure in solids
Authors: Linder C. , Armero F. 
Published: April 2007

AbstractThis paper presents new finite elements that incorporate strong discontinuities with linear interpolations of the displacement jumps for the modeling of failure in solids. The cases of interest are characterized by a localized cohesive law along a propagating discontinuity (e.g. a crack), with this propagation occurring in a general finite element mesh without remeshing. Plane problems are considered in the infinitesimal deformation range. The new elements are constructed by enhancing the strains of existing finite elements (including general displacement based, mixed, assumed and enhanced strain elements) with a series of strain modes that depend on the proper enhanced parameters local to the element. These strain modes are designed by identifying the strain fields to be captured exactly, including the rigid body motions of the two parts of a splitting element for a fully softened discontinuity, and the relative stretching of these parts for a linear tangential sliding of the discontinuity. This procedure accounts for the discrete kinematics of the underlying finite element and assures the lack of stress locking in general quadrilateral elements for linearly separating discontinuities, that is, spurious transfers of stresses through the discontinuity are avoided. The equations for the enhanced parameters are constructed by imposing the local equilibrium between the stresses in the bulk of the element and the tractions driving the aforementioned cohesive law, with the proper equilibrium operators to account for the linear kinematics of the discontinuity. Given the locality of all these considerations, the enhanced parameters can be eliminated by their static condensation at the element level, resulting in an efficient implementation of the resulting methods and involving minor modifications of an existing finite element code. A series of numerical tests and more general representative numerical simulations are presented to illustrate the performance of the new elements. Copyright © 2007 John Wiley & Sons, Ltd.
A p‐hierarchical adaptive procedure for the scaled boundary finite element method
Authors: Vu Thu Hang , Deeks Andrew J. 
Published: April 2007

AbstractThis paper describes a p‐hierarchical adaptive procedure based on minimizing the classical energy norm for the scaled boundary finite element method. The reference solution, which is the solution of the fine mesh formed by uniformly refining the current mesh element‐wise one order higher, is used to represent the unknown exact solution. The optimum mesh is assumed to be obtained when each element contributes equally to the global error. The refinement criteria and the energy norm‐based error estimator are described and formulated for the scaled boundary finite element method. The effectivity index is derived and used to examine quality of the proposed error estimator. An algorithm for implementing the proposed p‐hierarchical adaptive procedure is developed. Numerical studies are performed on various bounded domain and unbounded domain problems. The results reflect a number of key points. Higher‐order elements are shown to be highly efficient. The effectivity index indicates that the proposed error estimator based on the classical energy norm works effectively and that the reference solution employed is a high‐quality approximation of the exact solution. The proposed p‐hierarchical adaptive strategy works efficiently. Copyright © 2007 John Wiley & Sons, Ltd.
Simultaneous determination of four sesquiterpene alkaloids in Tripterygium wilfordii Hook. F. extracts by High‐performance liquid chromatography
Authors: OuYang Xiao‐kun , Jin Mi‐cong , He Chao‐hong 
Published: April 2007

AbstractWilfortrine, wilfordine, wilforgine and wilforine are four major bioactive sesquiterpene alkaloids in Tripterygium wilfordii Hook. F. The first analytical determination of the four major bioactive alkaloids is described. The four alkaloids are well‐resolved within 15 min using the developed HPLC method. The identity of the analytes was confirmed by an HPLC‐MS experiment, with all compounds being clearly assignable by atmospheric pressure chemical ionization (APCI) positive mode analysis. The method was validated for limit of qualification, linearity and inter‐day variation of precision and accuracy. Seven T. wilfordii samples (extracts and commercial product) were successfully analysed. Copyright © 2007 John Wiley & Sons, Ltd.
An analysis of excluded‐volume effects in a polystyrene‐cyclohexane system
Authors: Suzuki Hidematsu 
Published: April 2007

AbstractAn attempt was made to analyse Miyaki's data for the radius of gyration <s2> and the intrinsic viscosity [η] of very high molecular weight samples of polystyrene in cyclohexane. The excluded‐volume variable z was estimated by adopting the temperature dependence of the excluded‐volume integral as predicted by Eichinger. It was found that the volume expansion as given by the ratio of <s2> to <s2>0 under the unperturned state was a function of z only, as required by two‐parameter theories. These data were in good agreement with the Domb‐Barrett and the Suzuki equations. On the other hand, the ratio of [η] to [η] 0 under the unperturbed state also gave a single composite curve when plotted against z. However, it was found that the observed hydrodynamic behaviour was not satisfactorily explained by two‐parameter theories of [η]. A brief comment was made on the validity of two‐parameter theories from the experimental point of view.
Emulsion polymerisation in continuous reactor systems
Authors: Poehlein Gary W. 
Published: April 2007

AbstractContinuous reactor systems find important applications in the production of sythetic polymer latexes and increased production rates are providing additional incentives for the development of new continuous systems. The fundamental factors that should be considered in the development of continuous processes are reviewed in this paper. Particular emphasis is placed on exploring the differences between batch and continuous reactors and why these difference can lead to different latex product, even if the same recipe is employed. These factors make the task of designing continuous reactor systems based on batch research and development very difficult and risky. Thus it is recommended that small‐scale continuous reactors be employed early in a product/process development effort if that effort is likely to lead to a continuous commercial process.The published literature on continuous emulsion polymerization reactors has been reasonably active in the past ten years. Our understanding of the chemistry and reactor modelling has been advanced but a number of areas for fruitful research remains. Some of these problems are reviewed and directions for new efforts are suggested.
Curing polyester resins with visible light
Authors: Alexander Ian J. , Scott Roger J. 
Published: April 2007

AbstractRadiation curing of unsaturated polyester resin‐based compositions offers a number of significant advantages over the use of peroxides and similar free‐radical polymerisation initiators; the cure process can be closely controlled, is usually much faster, and the fabricator is not required to measure out, add, and blend‐in small quantities of catalyst. However most forms of radiation including ultra violet (UV) involve heavy initial expense and the need to provide shielding to protect personnel. Furthermore UV radiation will not usually penetrate deeply into thick glassfibre‐containing compositions owing to the absorption of UV light by both resin and glass.Photoinitiator systems which need only visible light have now been developed however. Using these systems almost any available light source including fluorescent tubes, tungsten filament bulbs and of course natural sunlight and daylight will cause the resin to cure rapidly and completely. By controlling the intensity of the incident light continuous close control of the cure process is easily achieved.The advantages of reduced energy requirements, fast cure,‘one pot’ chemistry and built‐in indicators of degree of cure have already led to a number of special applications for visible light curable polyester resins.
Crosslinking of a polyacrylate bearing a spiroorthoester pendant group with mixtures of diglycidyl ether of bisphenol A and phosphorus‐containing glycidyl derivatives
Authors: Canadell J. , Mantecón A. , Cádiz V. 
Published: April 2007

AbstractThe cationic crosslinking of a polyacrylate bearing a spiroorthoester pendant group with mixtures of diglycidyl ether of bisphenol A and three phosphorus‐containing glycidyl derivatives was carried out with ytterbium triflate as an initiator. The curing process was monitored with Fourier transform infrared spectroscopy. The thermomechanical and thermogravimetric properties were evaluated. The glass transition temperatures of the obtained materials were, in general, above 100 °C. The incorporation of phosphorus into the network increased the limiting oxygen index values, thus improving the flame retardancy of the materials. During crosslinking, all the crosslinked polymers showed slight shrinkage that was much lower than that observed in conventional epoxy resins. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1920–1930, 2007
Intrinsic conformational preferences of and an anomeric‐like effect in 1‐substituted silacyclohexanes
Authors: Weldon Abby Jones , Tschumper Gregory S. 
Published: April 2007

AbstractA series of ab initio computations have been performed to estimate the CCSD(T) complete basis set limit of the axial/equatorial energy difference for the chair conformation of 1‐fluoro, 1‐chloro, 1‐methyl, 1‐hydroxy, and 1‐methoxysilacyclohexanes. The equatorial conformation is more stable than the axial by 0.21 kcal mol−1 for 1‐methylsilacyclohexane, while the axial position is more stable for 1‐fluoro, 1‐chloro, and 1‐methoxysilacyclohexane (by 0.09, 0.40, and 0.15 kcal mol−1, respectively). The axial and equatorial orientations of 1‐hydroxysilacyclohexane are nearly electronically isoenergetic (equatorial favored by 0.03 kcal mol−1). Zero point vibrational energy corrections have very little effect on the relative energies (less than 0.08 kcal mol−1). These results suggest the presence of an interesting stereoelectronic effect, similar to the anomeric effect, in these silacyclohexanes even without an additional heteroatom, like O, in the ring. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Serum lipid and lipoprotein profile of patients with glycogen storage disease types I, III and IX
Authors: Geberhiwot T. , Alger S. , McKiernan P. , Packard C. , Caslake M. , Elias E. , Cramb R. 
Published: April 2007

SummaryWith current dietary therapy, life expectancy in glycogen storage disease (GSD) has improved considerably and more children reach adulthood. Notwithstanding intensive dietary therapy, moderate to severe hyperlipidaemia is still observed frequently. There is limited information about the type and extent of hyperlipidaemia. We studied the lipid profile in 20 patients, aged 8–54 years, of the three (types I, III and IX) most common forms of adult GSD. Hyperlipidaemia was shown to be type‐specific #Affecting predominantly patients with GSD type Ia, who showed marked combined hypercholesterolaemia and hypertriglyceridaemia. By contrast, a heterogeneous distribution of HDL was found in patients with GSD I and III. There was no significant difference in Apo Al and Apo B concentrations between groups. In addition, mass measurements of the fractions of VLDL1, VLDL2 and IDL were raised in all patients with GSD Ia by comparison with all other patients with GSD. Patients with GSD type Ia have lipid concentrations and individual mass measurements that are consistent with ranges found in patients who have a significant risk of atherosclerosis. Accumulated evidence, however, suggest GSD type Ia patients do not have an increased risk of atherosclerotic cardiovascular disease (CVD) but the reason remains unknown. Intervention to reduce their lipid levels could therefore be on the basis of seeking to prevent the risk of pancreatitis rather than that of CVD.
The Magnetic Field and the Central Core of the Earth
Authors: Knopoff Leon , MacDonald Gordon J. F. 
Published: April 2007

Summary
The suggestion that the inner core of the Earth is liquid and is the seat of a strong magnetic field is examined. Contrary to expectations of a magneto-hydrodynamic rigidity for the inner core, it is shown that a liquid inner core with a strong magnetic field should not transmit shear waves. The absence of the phase PKJKP in seismic records is favourable to the hypothesis of a strong magnetic field in a liquid inner core. If the jump in P wave velocity at the inner core boundary is due to a magnetic field, the strength of the field must be of the order of 5 × 106 G whether the field geometry is toroidal or random. A strong toroidal field leads to an apparent ellipticity of the inner core. No such ellipticity is observed, so that if the field in the inner core is toroidal, it must be less than 5 × 105 G. A random field does not lead to an ellipticity effect and no limit can be set on the magnitude of a random field.
The energy required for a magneto-hydrodynamic rigidity in the inner core is excessive. The magnetic energy is equally divided between the inner and outer cores. The hypothesis of a strong magnetic field in the inner core cannot explain the observed short period variations of the surface field.
The Evolution of the Indian Ocean since the Late Cretaceous
Authors: McKenzie Dan , Sclater John G. 
Published: April 2007

SummaryAll available ship and aeroplane tracks across the Indian Ocean were searched for identifiable magnetic anomalies and transform faults, and hence the age and direction of motion at the time of formation of about two-thirds of the floor of the ocean established. The magnetic lineations show that India moved away from Antarctica at about 18 cm/y for 20 My in the Early Tertiary. This rapid motion ceased in the Eocene and was followed by a period in which little or no spreading took place west of the Ninety East Ridge. Australia separated from Antarctica during this period. The present spreading episode began about 36 My ago. This detailed study has permitted instantaneous poles of rotation to be obtained, and has established that Africa is now moving northward at 2cm/y relative to Antarctica in the South West Indian Ocean. The evolution of the triple junction between the South East, South West and Central Indian Ridges is clearly reflected in the topography and magnetic lineations. The depth of parts of the ocean formed since the Late Cretaceous increases with age in the manner expected from the temperature structure of a cooling plate, and supports the evolution determined from the magnetic lineations in a most remarkable way. Heat flow observations are more scattered but also consistent with the same thermal model. The proposed evolution agrees with the distribution of known continental fragments and with the Late Cretaceous palaeomagnetic poles from surrounding continents and one obtained from the shape of the magnetic lineations south of India. It is, however, not yet clear how to reconstruct Gondwanaland from the Late Cretaceous reconstructions.
Iterative most-squares inversion: application to magnetotelluric data
Authors: Meju M. A. , Hutton V. R. S. 
Published: April 2007

Summary
Conventional least-squares inversion of geophysical observational data yields a model that fits the data best or within a specified tolerance. Due to the nature of practical data, bounding values of the optimal model parameters are often sought and routinely calculated from the covariance matrix of the least-squares solution. Jackson (1976) proposed the most-squares method as an alternative approach to determining bounding values in linear inversion. As an extension of Jackson's method, we present a stable iterative scheme for obtaining extreme parameter sets in non-linear inversion. The scheme is hybrid and combines the useful properties of the ridge regression (Marquardt 1970) and most-squares methods to solve the non-linear inverse problem. The observational errors and the inherent non-uniqueness in the inversion process are accounted for using a class of models that is consistent with the data. The method is flexible and the use of Twomey-Tikhonov type constraints also enables us to define and seek a preferred class of smooth models, especially for cases in which the sought subsurface physical properties show gradational changes. It is applied to magnetotelluric depth sounding data to demonstrate its potential as an appraisal tool for conventional least-squares models.
Geophysical parametrization and interpolation of irregular data using natural neighbours
Authors: Sambridge Malcolm , Braun Jean , McQueen Herbert 
Published: April 2007

Summary
An approach is presented for interpolating a property of the Earth (for example temperature or seismic velocity) specified at a series of ‘reference’ points with arbitrary distribution in two or three dimensions. The method makes use of some powerful algorithms from the field of computational geometry to efficiently partition the medium into ‘Delaunay’ triangles (in 2-D) or tetrahedra (in 3-D) constructed around the irregularly spaced reference points. The field can then be smoothly interpolated anywhere in the medium using a method known as natural-neighbour interpolation. This method has the following useful properties: (1) the original function values are recovered exactly at the reference points; (2) the interpolation is entirely local (every point is only influenced by its natural-neighbour nodes); and (3) the derivatives of the interpolated function are continuous everywhere except at the reference points. In addition, the ability to handle highly irregular distributions of nodes means that large variations in the scale-lengths of the interpolated function can be represented easily. These properties make the procedure ideally suited for ‘gridding’ of irregularly spaced geophysical data, or as the basis of parametrization in inverse problems such as seismic tomography.
We have extended the theory to produce expressions for the derivatives of the interpolated function. These may be calculated efficiently by modifying an existing algorithm which calculates the interpolated function using only local information. Full details of the theory and numerical algorithms are given. The new theory for function and derivative interpolation has applications to a range of geophysical interpolation and parametrization problems. In addition, it shows much promise when used as the basis of a finite-element procedure for numerical solution of partial differential equations.
Congenital tumours of the salivary gland: a case report and review
Authors: HARRIS M.D. , McKEEVER P. , ROBERTSON J.M. 
Published: April 2007

A congenital epithelial tumour of the submandibular salivary gland, occurring in a child of 10 months, is described. The lesion appeared benign and consisted of basal type cells, showing ductal and acinar differentiation with myoepithelial cells. The associated fibrous stroma contained blood vessels and small nerve bundles.A few similar lesions have been reported in the past, some of which showed features of malignancy. Although various names have been proposed, we suggest that these lesions represent a single group derived from a primitive cell line and advocate the use of the term sialoblastoma.
The renin‐secreting cell in polyarteritis—an immunocytochemical study
Authors: GRAHAM P.C. , LINDOP G.B.M. 
Published: April 2007

We studied kidney sections from 15 cases of polyarteritis using an immunocytochemical technique to demonstrate cells containing immunoreactive renin. Ten cases of classical polyarteritis nodosa showed hyperplasia of renin‐containing cells in areas of renal cortex with histological evidence of ischaemia—appearances indistinguishable from those seen in renal artery stenosis. Histologically normal cortex showed little or no immunostainable renin. In the ischaemic areas there was loss of the normal gradient of renin‐containing cells from superficial to deep cortex. In many cases this gradient was abolished or even reversed; in some cases most renin‐containing cells were in juxtaglomerular apparatuses. This alteration in the distribution of immunoreactive renin has only been described in renal artery stenosis in man. In five cases of microscopic polyarteritis there were fewer than normal numbers of renin‐containing cells.We suggest that in classical polyarteritis nodosa, focal ischaemia causes activation of the renin‐angiotensin system analogous to the changes caused by renal artery stenosis. This may be important in the pathogenesis of hypertension in this condition. By contrast, in microscopic polyarteritis, the appearances of the juxtaglomerular apparatus and the reduced amounts of immunostainable renin suggest suppression of renin synthesis.