bluuebunny/crossref_metadata_2025 huggingface dataset:
Low‐order macroelements for two‐ and three‐dimensional Stokes flow
Authors: Nafa K. , Thatcher R. W.
Published: August 2005

The use of low‐order elements for approximating fluid flow is attractive because all the elemental contributions can be quickly and easily obtained. One of the drawbacks is that low‐order elements often give rise to spurious pressure modes or incompatible velocity and pressure approximations. In this paper linear velocity and linear pressure elements are described for both two‐ and three‐dimensional flow that always produce stable solutions provided the elements are assembled into simple macroelements following easily used rules. Some examples of this idea are given for Stokes flow and compared with another popular low‐order method. © 1993 John Wiley & Sons, Inc.
Compact high‐order finite‐element method for elliptic transport problems with variable coefficients
Authors: MacKinnon R. J. , Langerman M. A.
Published: August 2005

We present a new conforming bilinear Petrov‐Galerkin finite‐element scheme for elliptic transport problems with variable coefficients. This scheme combines a generalized test function and artificial diffusion to achieve O(h4) grid‐point accuracy on uniform stencils of 3 × 3 in two dimensions without resorting to the extended stencils of high‐order elements. The method is compared with upwind and high‐order finite‐difference schemes and the standard Galerkin finite‐element method for representative test problems. © 1994 John Wiley & Sons, Inc.
Numerical study of the incremental unknowns method
Authors: Garcia Salvador
Published: August 2005

Through numerical experiments we explore the incremental unknowns method; linear stationary as well as evolutionary problems are considered. For linear stationary problems, the method appears as a nearly optimal two‐step preconditioning technique. At each step, we observe that the convergence behavior of the iterative methods employed is dramatically different, depending upon whether or not preconditioning is used. For linear evolutionary problems, successful and sharply accurate long‐term integration is observed when the incremental unknowns (other than that of the coarsest level) are, effectively, small quantities. Otherwise, systematical aliasing arises. © 1994 John Wiley & Sons, Inc.
Taylor‐Galerkin algorithms for viscoelastic flow: Application to a model problem
Authors: Carew E. O. , Townsend P. , Webster M. F.
Published: August 2005

Coupled and decoupled Taylor‐Galerkin algorithms are considered for viscoelastic flow and a model problem—transient startup Poiseuille flow in a channel under a fixed pressure gradient. All algorithms reproduce the steady‐state solutions and are stable at high elasticity numbers (E). For a fixed mesh, the coupled and decoupled versions (TGC and TGD) give exceptional time‐accuracy at low elasticity numbers [to within O(1%) at E = 1] and reasonable accuracy at high elasticity numbers [to within O(10%) at E = 10, 100]. By definition, the decoupled false‐transient scheme (TGF), which uses different time scales for velocity and stress time stepping, provides a poor transient history. Where the main requirement is to compute a steady‐state algorithm efficiency is crucial. The TGF scheme attains a steady state between six to eight times faster than does the TGC scheme, and the latter is over twice as fast as the TGD form. © 1994 John Wiley & Sons, Inc.
On the relationship between the moving finite‐element procedure and best piecewise L2 fits with adjustable nodes
Authors: Baines M. J.
Published: August 2005

It is shown that, for a class of time‐dependent partial differential equations of the form ut = ℒ︁u, one step of the moving finite‐element (MFE) procedure corresponds to one iteration of an algorithm for obtaining best L2 fits with adjustable nodes to continuous functions. In the steady‐state limit the MFE procedure gives the best fit of ℒ︁u, with adjustable nodes, to the null function. For first‐order partial differential equations, the MFE procedure moves nodes with approximate characteristic nodal speeds. We identify an additional speed component arising directly from the L2 projection which seeks a best fit in the sense described above. © 1994 John Wiley & Sons, Inc.
Numerical inaccuracies across the interface of a nested grid
Authors: Peggion Germana
Published: August 2005

This article addresses and discusses the inaccuracies in finite differencing across the interface of a nested grid. Explicit schemes for the advection and diffusion equations are analyzed on the fine and coarse grids and reformulated at the interface to guarantee that the evolving solution is unaffected by the abrupt change of the spatial grid resolution. The associated errors are expressed as a function of the wavelength of the initial field distribution and the ratio between the coarse and fine grid resolution. It is found that large‐scale features of the coarse grid must supply energy to sustain the small‐scale features of the fine grid. To not deplete the large‐scale motion, a source of energy must be given at the interface in the form of a computational diffusive term with negative viscosity coefficient. On the other hand, not all the energy of the small‐scale features of the fine grid has to be transferred to the large‐scale motion, but some of it needs to be computationally dissipated at the interface. © 1994 John Wiley & Sons, Inc.
Upwind finite difference schemes for linear conservation law with memory
Authors: Lin Yanping
Published: August 2005

In this article we consider upwind finite difference schemes for a class of linear conservation laws with memory. Assuming the positivity of the kernel, it is proved by using the energy estimates that the upwind finite difference scheme, explicit or implicit, is stable and convergent to the real solution. The numerical results of some examples, including Burger's equation with memory, are reported; the effect of memory is also discussed based on the numerical results. © 1994 John Wiley & Sons, Inc.
Low and moderate Reynolds number transient flow simulations using space filtered Navier‐Stokes equations
Authors: Cantekin M. E. , Westerink J. J. , Luettich R. A.
Published: August 2005

In this study, low and moderate Reynolds number flow problems in the laminar range are solved numerically with grids that do not resolve all the significant scales of motion. Spatial averaging or filtering of the Navier‐Stokes equations and Taylor series approximations to the filtered advective terms are used in order to account for the effects of the unresolved or subgrid scales on the resolved scales. Numerical experiments with a transient 2‐D lid driven cavity flow problem, using a penalty method Galerkin finite element code, show that this approach enhances the momentum transfer properties of the numerical solution, eliminates 2Δx type oscillations, and enables the use of coarser grids. The significance and order of the terms that describe the interaction between the resolved and the subgrid scales is studied and the success of the series approximations to these terms is demonstrated. © 1994 John Wiley & Sons, Inc.
Parallel evaluation of leftmost eigenpairs of large unsymmetric matrices
Authors: Pini G.
Published: August 2005

A parallel algorithm for the efficient calculation of m (m ⩽ 15) eigenvalues of smallest absolute magnitude for large sparse unsymmetric matrices is implemented and presented. The procedure employes a modification of the reverse simultaneous iteration scheme, which involves, among other things, the solution of m systems of linear equations. This phase is by far the most computationally demanding of the entire algorithm. However, efficient parallelization can be achieved, highly reducing the overall computational load. Numerical experiments consider the calculation of the m = 12 and m = 15 leftmost eigenvalues and eigenvectors of seven test matrices of varying size between n = 512 and n = 3564. All the computations are performed on a 4 CPU CRAY YMP8/432 machine. The accuracy of the eigenpairs found with the proposed algorithm is independent of the number of CPUs employed. Wall clock time and speed‐up measurements show that the scheme is efficient and robust and is well parallelized. In fact, average speed‐up factors of up to 3.72 were obtained. © 1994 John Wiley & Sons, Inc.
The performance of Bank‐Weiser's error estimator for quadrilateral finite elements
Authors: Ainsworth Mark
Published: August 2005

The error estimator proposed by Bank and Weiser is analyzed in the case of degree p finite element approximations on quadrilateral meshes. It is shown that the scheme is asymptotically exact in the energy norm for regular solutions provided that the degree of approximation is of odd order and the elements are rectangles. Perhaps surprisingly, the hypotheses are necessary, as counterexamples show. © 1994 John Wiley & Sons, Inc.
Some remarks on Zienkiewicz‐Zhu estimator
Authors: Rodríguez Rodolfo
Published: August 2005

In this article, Zienkiewicz‐Zhu estimator is analyzed for the piecewise linear finite element approximate solution of an elliptic problem. The estimator is proved to be equivalent to the error for the Poisson equation with a homogeneous Dirichlet boundary condition for any triangular regular mesh. No assumptions are needed about the regularity of the solution (i.e., solutions with corner singularities are not excluded). The estimator is also proved to be asymptotically exact on subdomains where the solution is smooth when parallel meshes are used. Therefore, its behavior is similar to that of other well‐known estimators. © 1994 John Wiley & Sons, Inc.
A novel numerical technique to investigate nonlinear guided waves: Approximation of nonlinear Schrödinger equation by nonperiodic pseudospectral methods
Authors: De Veronico C. , Funaro D. , Reali G. C.
Published: August 2005

A new numerical technique for investigating light waves guided by planar nonlinear dielectric films is presented. The method implements a multidomain spectral type approximation based on orthogonal algebraic polynomials, and makes possible to deal with nonperiodic boundary conditions and discontinuities of the data, overcoming the known deficiencies of the trigonometric polynomials. Results of preliminary numerical experiments for the solution of the nonlinear Schrödinger equation are presented. © 1994 John Wiley & Sons, Inc.
An approximate factorization scheme for elliptic grid generation with control functions
Authors: Mathur J. S. , Chakrabartty S. K.
Published: August 2005

An Alternating Direction Implicit (ADI), Approximate Factorization (AF) scheme is presented here for the solution of the two‐dimensional elliptic partial differential equations, with control functions as source terms, used for grid generation. This scheme requires significantly less computational effort than a Successive Over Relaxation (SOR) scheme. The dependence of the choice of the acceleration parameter on the rate of convergence of the AF scheme has been studied. As an example, grids generated by this method are shown, along with a comparison of the convergence history for the present AF and SOR schemes. © 1994 John Wiley & Sons, Inc.
ODE solvers and the method of lines
Authors: Shampine L. F.
Published: August 2005

Factors influencing the choice of ODE solver for the numerical solution of PDEs by the method of lines are investigated. The advection—diffusion equation is used to gain insight that is generalized to some classes of nonlinear PDEs. Numerical results for several nonlinear PDEs illustrate the theoretical developments. © 1994 John Wiley & Sons, Inc.
Some pointwise estimates for the finite element solution of a radial nonlinear Schrödinger equation on a class of nonuniform grids
Authors: Tourigny Yves
Published: August 2005

We prove new pointwise estimates for the time‐continuous finite element discretization of a nonlinear Schrödinger equation. The analysis relies on the energy method. A superconvergent estimate of the error gradient is derived and we obtain L∞ estimates via inverse inequalities. We emphasize the case of radial symmetry where the results improve on previously published L2 estimates by allowing greater flexibility in the choice of spatial grid. Some numerical results are presented, which confirm our theoretical findings. © 1994 John Wiley & Sons, Inc.
Superconvergence of finite element approximations to Maxwell's equations
Authors: Monk Peter
Published: August 2005

We study superconvergence of edge finite element approximations to the magnetostatic problem and to the time‐dependent Maxwell system. We show that in special discrete norms there is an increase of one power in the order of convergence of the finite element method compared to error estimates in standard Sobolev norms. Our results are restricted to an orthogonal grid inR3, but the grid may be nonuniform. © 1994 John Wiley & Sons, Inc.
Difference approximations for wave equations via finite elements II. Error analysis
Authors: Card Curtis L. , Allen Myron B.
Published: August 2005

Difference‐like schemes for the wave equation arise naturally from a Galerkin finite‐element formulation, if we adopt certain quadrature rules in evaluating the mass and stiffness matrices. One can extend these schemes to problems involving sharp interfaces by applying the quadrature on a refinement of the finite‐element grid that includes the interfaces. We develop error estimates for this modified scheme that corroborate numerical results for acoustic and elastic wave equations, presented in a companion article. © 1995 John Wiley & Sons, Inc.
Incremental unknowns for solving nonlinear eigenvalue problems: New multiresolution methods
Authors: Chehab Jean–Paul , Temam Roger
Published: August 2005

In this article, we present several numerical multilevel schemes for the solution of nonlinear eigenvalue problems. Using the Incremental Unknowns, we construct some generalization of the Marder and Weitzner method, which is well suited for the calculation of unstable solutions. The new methods that we present are based on a different treatment of the several structures appearing with the utilization of the hierarchical preconditioner. We illustrate the efficiency of the new methods with the calculation of unstable solutions of a reaction diffusion problem. © 1995 John Wiley & Sons, Inc.
Eulerian–Lagrangian localized adjoint methods for reactive transport with biodegradation
Authors: Wang Hong , Ewing Richard E. , Celia Michael A.
Published: August 2005

The microbial degradation of organic contaminants in the subsurface holds significant potential as a mechanism for in‐situ remediation strategies. The mathematical models that describe contaminant transport with biodegradation involve a set of advective–diffusive–reactive transport equations. These equations are coupled through the nonlinear reaction terms, which may involve reactions with all of the species and are themselves coupled to growth equations for the subsurface bacterial populations. In this article, we develop Eulerian–Lagrangian localized adjoint methods (ELLAM) to solve these transport equations. ELLAM are formulated to systematically adapt to the changing features of governing partial differential equations. The relative importance of retardation, advection, diffusion, and reaction is directly incorporated into the numerical method by judicious choice of the test functions that appear in the weak form of the governing equation. Different ELLAM schemes for linear variable–coefficient advective–diffusive–reactive transport equations are developed based on different operator splittings. Specific linearization techniques are discussed and are combined with the ELLAM schemes to solve the nonlinear, multispecies transport equations. © 1995 John Wiley & Sons, Inc.
On the solution of a 2‐D, parabolic, partial differential energy equation subjected to a nonlinear convective boundary condition via a simple solution for a uniform, Dirichlet boundary condition
Authors: Campo Antonio , Lacoa Ulises
Published: August 2005

Separate theoretical and numerical analyses have been conducted for the prediction of the mean bulk‐and wall‐temperatures of hot fluids flowing inside horizontal tubes. Heat transmission between the internal forced flow and the external free flow of the surrounding fluid occurs through the solid wall of the tube. The mathematical formulation of this problem is expressed in terms of a parabolic, partial differential equation with a temperature‐dependent, nonlinear boundary condition of third kind. The aim of the article is to critically examine the thermal response of this kind of in‐tube flows utilizing two different mathematical models: (a) a complete 2‐D differential model and (b) a largely simplified 1‐D lumped model. For the 1‐D lumped model, streamwise‐mean values for the internal Nusselt numbers and the circumferential‐mean values for the external Nusselt numbers have been taken from standard correlations that appear in basic textbooks. The combination of both mean Nusselt numbers leads to the calculation of a mean, equivalent Nusselt number, which serves to regulate the thermal interaction between the perpendicular fluid streams. For the two models tested, the computed results consistently demonstrate that the simplistic 1‐D lumped model provides accurate estimates of the mean bulk‐ and wall‐temperatures, when compared with those computed with the rigorous 2‐D differential model. The former is associated with hand calculations, whereas the latter inevitably necessitated a finite‐difference methodology and a personal computer. © 1995 John Wiley & Sons, Inc.
A moving grid finite‐element method using grid deformation
Authors: Semper Bill , Liao Guojun
Published: August 2005

A new front tracking method based on grid deformation is combined with a streamline upwind Petrov–Galerkin finite element method to produce an adaptive method for application to convection‐dominated transport equations. In this work, we examine the practicality of this approach and demonstrate the method on one‐dimensional examples. © 1995 John Wiley & Sons, Inc.
A biplicit spectral‐collocation‐type ansatz for the numerical integration of partial differential equations with the transversal method of lines
Authors: Reiter Johann
Published: August 2005

In the implicit formulation of the transversal method of lines, numerical instabilities (singular perturbation) do occur whenever “small” step sizes of the discretized variable have to be used for some reason. This problem can effectively be avoided if the derivatives with respect to the discretized variable are chosen using a combination of implicit and explicit methods (the biplicit method). This combination method uses piecewise defined trial functions involving a certain number of free parameters. The values of these parameters are found by the requirement that the trial functions approximate the solution of the implicit formulation of the method of lines. From a mathematical point of view, this spectral‐collocation‐type ansatz results in a multipoint boundary‐value problem with added parameters to be determined. Two numerical examples are presented in order to illustrate the performance of the method. © 1995 John Wiley & Sons, Inc.
Structures of three crystal modifications of poly(3,3‐dimethyloxacyclobutane)
Authors: Takahashi Yasuhiro , Osaki Yasunari , Tadokoro Hiroyuki
Published: August 2005

Three crystal modifications of poly(3,3‐dimethyloxacyclobutane) [CH2C(CH3)2CH2O]n were found and their structures were analyzed by x‐ray diffraction. Modification I is obtained only under tension and disappears on relaxing the tension. From the fiber period of 4.83 Å, the molecular structure seems to be planar zigzag. In modification II, two chains in T3GT3Ḡ conformation pass through a monoclinic cell with parameters a = 8.93 Å, b = 7.48 Å, c (fiber axis) = 8.35 Å, β = 97.9°, and the space group P21/c‐C. In modification III, two (T2G2)2 chains pass through an orthorhombic cell with parameters a = 15.60 Å, b = 5.74 Å, c (fiber axis) = 6.51 Å, and the space group, C2221–D. Molecular conformations of the three crystal modifications correspond to those of polyoxacyclobutane.
Stress relaxation of polymeric liquids after double‐step strain
Authors: Doi Masao
Published: August 2005

The stress relaxation of concentrated polymer solutions after double‐step strain is analyzed by the model of Doi and Edwards (DE model). The theory explains the experiments of Osaki et al., who showed that the Bernstein–Kearsley–Zapas (BKZ) constitutive equation works reasonably well when the successive deformations are applied in the same direction, but that it fails when the direction of the second deformation is reversed. This experimental result has been considered contrary to the DE model, since the previous theory of Doi and Edwards provides a BKZ‐type constitutive equation. In the present paper the discrepancy is reconciled by showing that (i) the source of the discrepancy is a mathematical approximation used in the previous DE theory, and that (ii) if this approximation is removed, the agreement between the theory and experiment becomes fairly good.
Piezoelectricity and pyroelectricity of polyvinylidene fluoride corona‐poled at elevated temperature
Authors: Bamji S. S. , Kao K. J. , Perlman M. M.
Published: August 2005

X‐ray diffraction, thermally stimulated depolarization, and piezoelectric and pyroelectric current measurements have been carried out on biaxially oriented polyvinylidene fluoride film, corona‐poled both negatively and positively, at elevated temperature. Larger piezoelectric and pyroelectric coefficients are obtained at lower values of the poling field, when corona charging takes place at elevated temperature rather than room temperature. Negative charging is more effective than positive. The polarization mechanism is dipole alignment, and a conversion of Form‐II crystallites to Form I. The large space‐charge injected by the corona, and trapped in the material, acts through creation of high internal fields, and shows little, if any, piezoelectric and pyroelectric effects of its own.
“Super microcapsules” (SMC). I. Preparation and characterization of star polymethylene oxide (PEO)polylactide (PLA) copolymers
Authors: Zhu K. J. , Bihai Song , Shilin Yang
Published: August 2005

A new model of molecular scale microcapsule named “super microcapsule” (SMC) obtained from a star copolymer consisting of hydrophilic and hydrophobic blocks was presented. As a first stage, 3 and 4‐arm star polyethylene oxide‐polylactide copolymers (s‐PEO‐PLA) were synthesized by the use of triethanolamine and pentaerythritol and initiating agent, respectively. The block length of PLA and PEO for the copolymers can be controlled by feed and reaction conditions. The molecular weight distributions found to be in the range of 1.3–1.7. The DTA data indicated that the phase separation behavior of s‐PEOPLA copolymers is different from that of linear PEOPLA copolymers with comparable block length. As a evidence of SMC, the shell‐core structure of s‐PEOPLA copolymers in solid state was observed by TEM. The SMC dimensions were estimated to be about 400–1000 Å
Cationic polymerization of α‐methylstyrene in dichloromethane initiated with system 2,5‐dichloro‐2,5‐dimethylhexene‐BCl3. II. Continuous addition of monomer into initiator, quasiliving polymerization
Authors: Toman Luděk , Pokorný Svatopluk , Spěváček Jiří
Published: August 2005

A slow continuous addition of dichloromethana solutions of α‐methylstyrene (α‐MeSt) into a dichloromethane solution of 2,5‐dichloro‐2,5‐dimethylhexane (DDH) with BCI3 (initiating system II) prepared in advance resulted, in the temperature range between −20 and −40°, in a quasilving polymerization of α‐MeSt. At −20°C and a 100% conversion a polymer with a very narrow molecular weight distribution is formed, M̄w/M̄n ‐ 1.1. Quasiliving polymerization of α‐MeSt has not been achieved with freshly prepared dischloromethane solutions of DDH with BC3 (initiating sytem I), or with solutions of BCI3 alone (initiating system III). Polarity of the polymerization medium affected molecular weight distribution (MWD) of the polymer, and the polydispersity index decreased with decreasing polarity. MWD of the polymer samples were studied by the GPC method, the structure of poly (α‐methylstyrene) (Pα‐MeSt) was investigated by the 1H‐NMR analysis
Syntheses and properties of 4‐hydroxy‐3,5‐dibromobenzyl phosphonates and their flame‐retarding effects on ABS copolymer
Authors: Yang Chin‐Ping , Lee Tzong‐Ming
Published: August 2005

4‐Hydroxy‐3,5‐dibromobenzyl phosphonates (HDBBP) were synthesized by reacting phosphites with 4‐hydroxy‐3,5‐dibromobenzyl bromide (HDBBB) which was prepared in advance by photobromination of 2,6‐dibromo‐p‐cresol (DBPC) produced by bromination of p‐cresol. In the reactions between HDBBB and phosphites, the rate of formation of dimethyl 4‐hydroxy‐3,5‐dibromobenzyl phosphonate (HDBBPm) was greater than that of diphenyl 4‐hydroxy‐3,5‐dibromobenzyl phosphonate (HDBBPP); however, quantitative yields for both products were obtainable. The addition of HDBBP as bromine and phosphorus containing flame‐retardants to ABS copolymer showed better results than the addition of the same amount of brominated compound, or mixtures of both two compounds. It was also proved that compound containing both bromine and phosphorus exhibited more apparent synergistic effects on flame retardancy than the mixtures of brominated compound and phosphorous containing compound
Free radical copolymerization of sulfur dioxide with 1‐alkynes
Authors: Kim Seong‐Ju , Matsuda Minoru
Published: August 2005

Free radical copolymerization of SO2 with 1‐alkynes (AY) was studied by evaluation of the copolymerization rate under controlled conditions of copolymerization temperature and monomer concentration product ([AY][SO2]). The poly(alkyne sulfone)s always contained equimolar units of SO2 and alkyne, regardless of the copolymerization conditions. Using 1‐hexyne (HY) and 1‐octyne (OY) as comonomers of SO2, the values of ceiling temperature (Tc) were determined: when [HY][SO2] = [OY][SO2] = 0.25 mol2/L2, the values of Tc were 90.5 and 84.5°C, respectively. Tc increases with increasing monomer concentration product. The activation energies for propagation (Ep) and depropagation (Ed) of the SO2‐alkynes copolymerization system were investigated, using the SO2OY copolymerization system, and estimated to be 12.2 and 26.7 kcal/mol, respectively. The value of Ed is high compared with that of the copolymerization of SO2 and 1‐butene (20.3 kcal/mol), demonstrating that the free radical endings (∼ OYSO2 and ∼ SO2OY) are difficult to depropagate, compared with those formed from the copolymerizaton of SO2 and 1‐butene. ΔS and ΔHp, calculated from experiments, were found to be −37.7 cal/mol K and −14.3 kcal/mol, respectively
Polymer degradation under ionizing radiation: The role of ozone
Authors: Clough R. L. , Gillen K. T.
Published: August 2005

Gamma‐radiation degradation of poly(butadiene‐co‐styene) [SBR rubber] and poly(butadiene‐co‐acrylonitrile) [Buna‐n rubber] in the presence of air has been investigated. Using a recently‐developed modulus profiling techniques, it is shown that the degradation of these materials is very heterogenous through the sample thickness. There is a broad, paraboloidally‐shaped modulus profile through the sample interior, together with a dramatic change in modulus in the surface regions. Mechanistic investigations lead to the conclusion that the radiation‐inducted degradatoin of these materials results from two different process: (1) the standard free radical‐mediated radiation chemistry, which gives rise to oxidation involving O2 dissolved in the polymer and which leads to heterogenous oxidation due to oxygen diffusion effects; and (2) ozone chemistry in the surface regions of the samples, which results from attack by O3 generated by the action of the ionizing radiation on the air atmosphere surrounding the samples. It appears that the intense role which this ozone mechanism can play in radiation‐induced oxidative degradation of polymers has not been widely appreciated. This study provides evidence that the simultaneous action of ozone and ionizing radiation can in fact be strongly synergistic in their effect on organic materials
A study of the mechanism of aniline polymerization
Authors: Wei Yen , Tang Xun , Sun Yan , Focke Walter W.
Published: August 2005

A chemical polymerization of aniline is quenched at specific reaction time intervals and the amounts of unreacted aniline and formed p‐aminodiphenylamine is observed. Oxidation of aniline to generate p‐aminodiphenylamine is observed. Oxidation of aniline to generate p‐aminodiphenylamine is the slow step in the plymerization. Furthermore, the tetramer of aniline is used as starting material for polymerization under the same conditions as polymerization of aniline. Direct coupling of two tetramers leading to polymer is not observed. A mechanism of polymerization of aniline is proposed
Thioether glycidyl resins. VI. Reaction products of opening of oxirane ring of phenylthioetherglycidyl resin and of some derivatives under the influence of temperature
Authors: Charmas Władysław , Podkościelny Wawrzyniec , Brunn Joachim
Published: August 2005

The process of oxirane ring opening of thioether glycidyl resins under various temperatures has been described. Reaction rate constants (k) and the activaton parameters (Eα, ΔH*, ΔS*) for epoxy group loss of 1,2‐epoxy‐3‐(phenylthio)propane, 1,2‐epoxy‐3‐(p‐tolythio)propane, and 1,2‐epoxy‐3‐(p‐chloro‐phenylthio)propane using classical kinetic methods were determined. The reaction products were separated and analyzed by means of chromatography and the structure of the compounds was determined by means of the spectral analyses: IR, 1H‐NMR, and 13C‐NMR
Thermoplasticization of wood. I. Benzylation of wood
Authors: Hon David N.‐S. , Ou Nian‐Hua
Published: August 2005

A study of converting wood into thermoplastic materials was undertaken to develop a new technique in effective utilization of wood wastes. Thermoplasticizatoin of wood carried out by means benzylation. Various reaction parameters, such as alkalinity of reaction media, reaction temperature, and time were taken into account to produce benzylated wood with different degrees of substitution (based on weight gain) FTIR, DSC, DMTA, SEM and x‐ray crystallography were used to characterize the chemical and mechanical properties of benzylated wood. Experimental data showed that preswelling and reaction temperature had critical effects on benzylation reaction. Lignin in wood appeared to inhibit benzylation but extractives had little effect. Different species showed some variation in reaction rates. The thermoplasticized wood exhibited good melting properties and were readily molded into bulk materials or extruded into films and sheets. A wide range of glass transition temperatures from 66 to 280°C for the benezylatedwoods was achieved, and they were larely dependent on the weight gain. The molded and extruded products exhibited acceptable mechanical strength for structural engineering applications. The property and structure relationship for the thermoplasticized wood were discussed
Effect of aging on fractional crystallization of poly(ethylene oxide) component in poly(ethylene oxide)/poly(3‐hydroxybutyrate) blends
Authors: Zhao Li , Kai Weihua , He Yong , Zhu Bo , Inoue Yoshio
Published: August 2005

The effect of aging on the fractional crystallization of the poly(ethylene oxide) (PEO) component in the PEO/poly(3‐hydroxybutyrate) (PHB) blend has been investigated. The partial miscibility of the PEO/PHB blends with high PEO molecular weight (Mv = 2.0 × 105 g/mol) was confirmed by differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis. The fractional crystallization behavior of the PEO component in the PEO/PHB blends with low PEO content (not more than 30 wt% of PEO), before and after aging under vacuum at 25 °C for 6 months, were compared by DSC, fourier transform infrared microscopic spectroscopy, small angle X‐ray diffraction, and scanning electron microscopy. It was confirmed that nearly all the PEO components remain trapped within interlamellar regions of PHB for the PEO/PHB blends before aging. Under this condition, the crystallization of PEO is basically induced by much less active heterogeneities or homogeneous nucleation at high supercoolings. While, after the same PEO/PHB samples were stored at 25 °C in vacuum for 6 months, a part of the PEO component was expelled from the interlamellar region of PHB. Under this condition, the expelled PEO forms many separate domains with bigger size and crystallizes at low supercoolings by active heterogeneous nucleation, whereas the crystallization of PEO in the interlamellar region is still mainly induced by less active heterogeneities or homogeneous nucleation at extreme supercoolings. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2665–2676, 2005
Rheological properties and interfacial slip of a multilayer structure under dynamic shear
Authors: Jiang L. , Lam Y. C. , Zhang J.
Published: August 2005

Interfacial slip between polymer melt under steady shear has been studied using a simplified multilayer structure. In this investigation, interfacial slip under dynamic shear was studied by calculating the angular displacements of the multilayer structure and its component layers. On the basis of the angular displacements, a slip index was defined to quantify the degree of interfacial slip. A relationship governing the rheological behavior of the multilayer structure under slip and nonslip condition was established. These results were correlated with equations derived from consideration of energy equilibrium in the multilayer structure. Polymer multilayer structures of high‐density polyethylene/polystyrene and liquid crystal polymer(LCP)/poly ethylene naphthalate(PEN) were investigated. Of all the polymers investigated, large interfacial slip was found at LCP/PEN interface under dynamic shear. The high rigidity and alignment along the interface of LCP molecules was believed to prevent chain entanglement in the interfacial layer and therefore promote interfacial slip at the interface. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2683–2693, 2005
Crystal structure of poly(dithiotriethylene adipate)
Authors: Finelli Lara , Gazzano Massimo , Lotti Nadia , Malta Viscardo , Munari Andrea
Published: August 2005

The crystal structure of poly(dithiotriethylene adipate) has been determined through the best fitting of calculated and experimental X‐ray diffraction powder profiles. A triclinic cell was found with dimensionsa= 4.942 (7) Å,b= 4.702 (2) Å,c= 20.56 (2) Å, α = 88.9 (2)°, β = 61.0 (1)°, γ = 67.8 (1)°, P‐1 space group, and one chain in the unit cell. A full extended trans conformation of the chain fitted satisfactory the experimental data, yielding to a discrepancy factorRp= 0.073. A comparison between the crystal structures of poly(dithiotriethylene adipate) and poly (thiodiethylene adipate) is proposed. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2677–2682, 2005
Development of Poly(propylene) Surface Topography During Corona Treatment
Authors: Jones Viv , Strobel Mark , Prokosch Michael J.
Published: August 2005

Summary: Atomic force microscopy (AFM), contact‐angle measurements, and X‐ray photoelectron spectroscopy (XPS or ESCA) were used to characterize biaxially oriented poly(propylene) (PP) films modified by exposure to a corona discharge. Surface analysis was performed on PP films modified at various corona energies to explore the changes in surface topography, wettability, and oxidation state resulting from the corona treatment. Even at low corona energies, water‐soluble low‐molecular‐weight oxidized materials (LMWOM) are formed. These LMWOM products agglomerate into small topographical mounds that are visible in the AFM images. For the detection of LMWOM on corona‐treated surfaces, AFM appears to be at least as sensitive as contact‐angle measurements or ESCA. A major advantage of AFM relative to the other surface analytical techniques used to confirm the presence of the LMWOM is that no washing of the surface with water is required in conjunction with the AFM analysis.

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Influence of Non‐Polymerizable Gases Added During Plasma Polymerization
Authors: Hegemann Dirk , Hossain Mohammad‐Mokbul
Published: August 2005

Summary: In plasma polymerization often additional, non‐polymerizable gases are used, either as carrier gas or as reactive co‐monomer. The gas ratio represents an additional parameter, which complicates the understanding of plasma polymerization processes. Therefore, we thoroughly investigated the deposition rates of different gas mixtures (O2/HMDSO, N2 and NH3/CxHy, as well as inert gas/CxHy) on the basis of a macroscopic approach. Since the mass deposition rates depend on the specific energy W/F, the plasma polymerization regime for the corresponding polymerizable monomer can be identified by introduction of a modified flow F = Fm + a Fc (sum of monomer flow Fm and carrier gas flow Fc with a flow factor a). Any deviations discovered during application of this novel approach indicate additional effects, such as ion‐induced effects.

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LEAFY COTYLEDON 2 activation is sufficient to trigger the accumulation of oil and seed specific mRNAs in Arabidopsis leaves
Authors: Santos Mendoza Monica , Dubreucq Bertrand , Miquel Martine , Caboche Michel , Lepiniec Loïc
Published: August 2005

LEAFY COTYLEDON 2 (LEC2) is a key regulator of seed maturation in Arabidopsis. To unravel some of its complex pleiotropic functions, analyses were performed with transgenic plants expressing an inducible LEC2:GR protein. The chimeric protein is functional and can complement lec2 mutation. Interestingly, the induction of LEC2 leads to the accumulation of storage oil in leaves. In addition, short‐term induction and use of translation inhibitors allowed to demonstrate that LEC2 can directly trigger the accumulation of seed specific mRNAs. Consistent with these results, the expression of three other major seed regulators namely, LEC1, FUS3, and ABI3 were also induced by LEC2 activation.
Importance of a repetitive nine‐residue sequence motif for intracellular stability and functional structure of a family I.3 lipase
Authors: Angkawidjaja Clement , Paul Aditya , Koga Yuichi , Takano Kazufumi , Kanaya Shigenori
Published: August 2005

PML5 is a functional derivative of a family I.3 lipase from Pseudomonas sp. MIS38 and contains five repeats of a nine‐residue sequence motif. Two aspartate residues within the second and third repetitive sequences of PML5 were replaced by Ala. The secretion level, intracellular accumulation level, and stability of the resultant mutant protein were greatly reduced as compared to those of PML5. In addition, this mutant protein was inactive and did not bind Ca2+ ion. We propose that the repetitive sequences of PML5 form a β‐roll structure in the cells and thereby contribute to the intracellular stability and secretion efficiency of the protein.
Mammalian NHE2 Na+/H+ exchanger mediates efflux of potassium upon heterologous expression in yeast
Authors: Flegelova Hana , Sychrova Hana
Published: August 2005

Na+/H+ exchangers form a broad family of transporters that mediate opposing fluxes of alkali metal cations and protons across cell membranes. They play multiple roles in different organisms (protection from toxic cations, regulation of cell volume or pH). Rat NHE2 exchanger was expressed in a Saccharomyces cerevisiae mutant strain lacking its own exporters of alkali metal cations. Though most of the overexpressed NHE2 remained entrapped in the secretory pathway, part of it reached the plasma membrane and mediated K+ efflux from the yeast. We demonstrate for the first time that a mammalian Na+/H+ exchanger transports alkali metal cations in yeast in the opposite direction than in mammalian cells, and that the substrate specificity of the rat NHE2 exchanger is limited only to potassium cations upon expression in yeast cells.
Effects of N‐acylethanolamines on the respiratory chain and production of reactive oxygen species in heart mitochondria
Authors: Wasilewski Michał , Wojtczak Lech
Published: August 2005

Long‐chain N‐acylethanolamines (NAEs) have been found to uncouple oxidative phosphorylation and to inhibit uncoupled respiration of rat heart mitochondria [Wasilewski, M., Więckowski, M.R., Dymkowska, D. and Wojtczak, L. (2004) Biochim. Biophys. Acta 1657, 151–163]. The aim of the present work was to investigate in more detail the mechanism of the inhibitory effects of NAEs on the respiratory chain. In connection with this, we also investigated a possible action of NAEs on the generation of reactive oxygen species (ROS) by respiring rat heart mitochondria. It was found that unsaturated NAEs, N‐oleoylethanolamine (N‐Ole) and, to a greater extent, N‐arachidonoylethanolamine (N‐Ara), inhibited predominantly complex I of the respiratory chain, with a much weaker effect on complexes II and III, and no effect on complex IV. Saturated N‐palmitoylethanolamine had a much smaller effect compared to unsaturated NAEs. N‐Ara and N‐Ole were found to decrease ROS formation, apparently due to their uncoupling action. However, under specific conditions, N‐Ara slightly but significantly stimulated ROS generation in uncoupled conditions, probably due to its inhibitory effect on complex I. These results may contribute to our better understanding of physiological roles of NAEs in protection against ischemia and in induction of programmed cell death.
The upstream area of the chicken α‐globin gene domain is transcribed in both directions in the same cells
Authors: Borunova Victoria , Iarovaia Olga V. , Vassetzky Yegor S. , Razin Sergey V.
Published: August 2005

It was demonstrated previously that in erythroid chicken cells an extended upstream area of the α‐globin gene domain is transcribed in both directions as a part of ggPRX gene and a part of a full domain transcript of the α‐globin gene domain. Here, we show that both DNA chains of the above‐mentioned region are transcribed in the same cells and that the corresponding transcripts coexist in nuclei. The data obtained suggest that cells possess a molecular mechanism which in some cases prevents the formation of dsRNA and subsequent destruction of both transcripts in spite of the presence of complementary RNA chains in the cell nucleus.
Krüppel‐like factor 5 promotes mitosis by activating the cyclin B1/Cdc2 complex during oncogenic Ras‐mediated transformation
Authors: Nandan Mandayam O. , Chanchevalap Sengthong , Dalton W. Brian , Yang Vincent W.
Published: August 2005

We previously showed that the zinc finger‐containing transcription factor Krüppel‐like factor 5 (KLF5) is important in mediating transformation by oncogenic H‐Ras through induction of cyclin D1 expression and acceleration of the G1/S transition of the cell cycle. Here we present evidence of a role for KLF5 in accelerating mitotic entry in H‐Ras‐transformed NIH3T3 fibroblasts. When compared with non‐transformed parental NIH3T3 cells, H‐Ras‐transformed fibroblasts exhibit an increase in mitotic index, levels of cyclin B1 and Cdc2, and cyclin B1/Cdc2 kinase activity. Inhibition of KLF5 expression in H‐Ras‐transformed cells with KLF5‐specific small interfering RNA (siRNA) results in a decrease in each of the aforementioned parameters, with a concomitant reduction in the transforming potential of the cells. Conversely, over‐expression of KLF5 in NIH3T3 cells leads to an increase in the promoter activity of the genes encoding cyclin B1 and Cdc2. These results indicate that KLF5 accelerates mitotic entry in H‐Ras‐transformed cells by transcriptionally activating cyclin B1 and Cdc2, which leads to an increase in cyclin B1/Cdc2 kinase activity. Extending our previous observation that KLF5 activates cyclin D1 transcription to promote G1/S transition, our current results further support a crucial function for KLF5 in mediating cellular transformation caused by oncogenic H‐Ras.
A previously found thylakoid membrane protein of 14 kDa (TMP14) is a novel subunit of plant photosystem I and is designated PSI‐P
Authors: Khrouchtchova Anastassia , Hansson Maria , Paakkarinen Virpi , Vainonen Julia P. , Zhang Suping , Jensen Poul Erik , Scheller Henrik Vibe , Vener Alexander V. , Aro Eva-Mari , Haldrup Anna
Published: August 2005

We show that the thylakoid membrane phosphoprotein TMP14 is a novel subunit of plant photosystem I (PSI). Blue native/SDS–PAGE and sucrose gradient fractionation demonstrated the association of the protein exclusively with PSI. We designate the protein PSI‐P. The presence of PSI‐P subunit in Arabidopsis mutants lacking other PSI subunits was analyzed and suggested a location in the proximity of PSI‐L, ‐H and ‐O subunits. The PSI‐P protein was not differentially phosphorylated in state 1 and state 2.
Quasi‐periodic backscatters from the E region at Gadanki: Evidence for Kelvin‐Helmholtz billows in the lower thermosphere?
Authors: Choudhary R. K. , St.‐Maurice J.‐P. , Kagan L. M. , Mahajan K. K.
Published: August 2005

Analyzing the field‐aligned coherent radar backscatter observed over Gadanki, India (13.5°N, 79.2°E), with a narrow beam pointing almost vertically, we present convincing experimental evidence for the presence of low‐latitudes tilted sporadic ionization layers close to 10 km in vertical extent that move horizontally through the field of view of the radar. Using the data from high temporal (∼3 s) resolution experiments, we also show that the line‐of‐sight Doppler velocities associated with at least some of the quasi‐periodic striations have very clear vortex‐like structures cutting across a vertical plane inside regions of strong horizontal wind shears. The power as well as the Doppler width peak together, and they often reach their peak values near the center of a vortex, where the magnitude of the Doppler velocity is minimum. The Doppler properties and spatial distribution of the 3 m echoes are explained in terms of a local electrodynamical process that makes ions and electrons move with the vertical neutral wind. Both the wind field and the tilt of the layers are in turn consistent with the presence of Kelvin‐Helmholtz billows. We postulate that the billows themselves are triggered by a shear instability in the large ambient zonal wind; strong zonal wind shears clearly have to be present when sporadic E layers are observed. In our case, the breaking of an originally uniform and horizontal sporadic E layer into tilted pieces aligned more or less parallel to one another, and their motion through the radar field of view in the presence of a mean zonal wind, give the echoes their quasi‐periodic appearance.
Deep mantle heat flow and thermal evolution of the Earth's core in thermochemical multiphase models of mantle convection
Authors: Nakagawa Takashi , Tackley Paul J.
Published: August 2005

A coupled model of thermochemical multiphase mantle convection and parameterized heat balance in the Earth's core is used to investigate the need for radioactive potassium in the core, and chemical layering above the core‐mantle boundary (CMB), to obtain a successful thermal evolution of the core, i.e., one in which the magnetic field exists over geological time and the final inner core size matches that observed. The mantle convection model includes both the olivine and pyroxene phase change systems linked via the compositional field. The most successful core thermal evolution is obtained when the compositional density difference between subducted MORB and pyrolite in the deep mantle is 1.1% and the core contains 100 ppm radioactive potassium, both of which are consistent with estimates from laboratory experiments. In that scenario, the CMB heat flow at the present time is 8.5 TW, and the time‐averaged ohmic dissipation is 2 TW. However, during the modeled magnetic evolution, the ohmic dissipation associated with the geodynamo occasionally becomes zero, which means that the geodynamo stops working, although these large fluctuations could be an artifact of two‐dimensional geometry. Various model uncertainties still remain.