bluuebunny/crossref_metadata_2025 huggingface dataset:
Glial fibrillary acidic protein messenger RNA and glutamine synthetase activity after nervous system injury
Authors: Condorelli D. F. , Dell'Albani P. , Kaczmarek L. , Messina L. , Spampinato G. , Avola R. , Messina A. , Stella A. M. Giuffrida
Published: February 2006

The level of the mRNA for glial fibrillary acidic protein (GFAP), the major protein of the intermediate filaments of astroglial cells, and the activity of glutamine synthetase (GS), an enzyme selectively localized in astrocytes, were measured at different times after a unilateral mechanical lesion in the rat cerebral cortex. A rapid and early increase (6 hours post‐lesion) in GFAP mRNA was observed; GFAP mRNA level reached a peak at 1–3 days and then decreased. Moreover, an astrocytic activation in cortical zones far from the injury site and in the contralateral hemisphere was detected. No change of GS activity was observed in the same model of brain injury, showing that this astroglial marker is not modified during the reactive gliosis obtained with this experimental model. GFAP mRNA has also been detected in the rat sciatic nerve; however, its level was not modified after nerve transection, suggesting a different regulation of GFAP expression in the peripheral nervous system.
Réaction de Fries appliquée aux poly(vinyl‐4 benzoates de phényl)
Authors: Pinazzi Christian , Fernandez Alain
Published: February 2006

Les vinyl‐4 benzoates de phényle (3a) et de méthoxy‐3 phényle (3b) ont été synthétisés et polymérisés par voie radicalaire. Leur copolymérisation avec le styrène montre une aptitude plus grande à la polymérisation que ce dernier. Les polymères de 3a et 3b ont été traités dans les conditions de la réaction de Fries chimique. Les caractéristiques spectrales des structures attendues dans la réaction de réarrangement ont été déterminées à l'aide d'homopolymères modèles. L'étude de la réaction dans les deux cas a été réalisée en couplant les données des spectres d'absorption UV avec une méthode programmée de calcul. Les résultats traduisent un mécanisme intermoléculaire avec une formation d'acide plus importante que dans le cas de molécules organiques. La réaction du poly(vinyl‐4 benzoate de méthoxy‐3 phényle) (4b) conduit à un polymère contenant une forte proportion de groupes hydroxy‐2 benzoyl phenyle.
Synthèse par voie radicalaire de polymères à extrémités hydroxylées, 5. Polymérisation du méthacrylate de méthyle sous rayonnement ultraviolet
Authors: Pinazzi Christian , Lenain Jean‐Claude , Brosse Jean‐Claude , Legeay Gilbert
Published: February 2006

Sous l'action du rayonnement ultra‐violet (253,7 nm), le peroxyde d'hydrogène est scindé en radicaux hydroxyle pouvant agir comme agents d'amorcage d'un processus de polymérisation. On peut ainsi obtenir des polymères hydroxytéléchéliques. L'adjonction d'un alcool au milieu réactionnel modifie les conditions de la polymérisation et permet de moduler les taux de conversion et les masses molécularies moyennes en nombre. Les résultats sont différents selon que le polymère est soluble ou non dans l'alcool. La polymérisation du méthacrylate de méthyle selon ce procédé, dans le méthanol non‐solvant du polymère, fait l'object du présent travail. La nature des polymères obtenus est déterminée: mode de distribution des masses moléculaires, microstructure, taux de groupements hydroxyle par macromolécule; l'influence de divers paramètres est également étudiée: durée, proportions d'eau oxygénée, nature du milieu réactionnel.
Mechanism of interfacial polycondensation and the direct synthesis of stable polyamide membranes
Authors: Enkelmann Volker , Wegner Gerhard
Published: February 2006

The mechanism of membrane formation by interfacial polycondensation was studied. For the time‐conversion curves the equation

was derived (x′ = reduced membrane thickness). The membrane morphology was investigated by x‐ray scattering and electron microscopy. It was found that the polymer chains are mainly oriented perpendicularly to the interface in the direction of membrane growth. The order of chain packing decreases with increasing thickness. Stable polyamide membranes consisting of two layers can be obtained by formation of a supporting layer of crosslinked copolyamide on a thin layer of Nylon‐6,10. The swelling properties of these membranes were studied.
Polymere Imidazolcarbonsäuren, 1. Darstellung und Eigenschaften einiger vernetzter Polyvinylimidazolcarbonsäuren
Authors: Manecke Georg , Schlegel Rainer
Published: February 2006

Durch radikalische Lösungsmittelpolymerisation einiger vinylsubstituierter Imidazolcarbonsäureester wurden Homopolymere erhalten und deren Eigenschaften untersucht. Der 1‐Vinylimidazol‐4‐carbonsäure‐methylester (1b), der 1‐Vinylimidazol‐4,5‐dicarbonsäure‐dimethylester (1d), sowie der 2‐(p‐Vinylphenyl)imidazol‐4,5‐dicarbonsäure‐dimethylester (3a) wurden mit Divinylbenzol (DVB) copolymerisiert. Durch alkalische Verseifung der Copolymeren wurden die neuen Chelatharze 5–7 erhalten. Zur Charakterisierung wurden die scheinbaren Dissoziationskonstanten pK′ der Harze bestimmt. Das Quellverhalten bei verschiedenen pH‐Werten, das Bindungsvermögen der Harze für Cu2+‐Ionen bei pH 5,0 und die Zeitabhängigkeit der Cu2+‐Ionenaufnahme wurden untersucht.
The synthesis of monomers that expand on polymerization. Synthesis and polymerization of 8,10,19,20‐tetraoxatrispiro[5.2.2.5.2.2]heneicosane
Authors: Endo Takeshi , Katsuki Hirokazu , Bailey William J.
Published: February 2006

A spiro orthocarbonate containing two cyclohexyl groups, 8,10,19,20‐tetraoxatrispiro[5.2.2.5.2.2]heneicosane (1), was prepared. The monomer was polymerized with Lewis acids such as boron trifluoride etherate or stannic chloride as catalysts. The IR and NMR spectra indicated that the polymer was an alternating copolymer with ether and carbonate linkages. This monomer underwent expansion on polymerization.
Stereochemistry of copolymerization of optically active cyclohexylepoxyethane with carbon dioxide
Authors: Hirano Takashi , Inoue Shohei , Tsuruta Teiji
Published: February 2006

The stereochemistry of alternating copolymerization of carbon dioxide with S‐(+)‐cyclohexylepoxyethane (1) using a diethylzinc/water system as catalyst was investigated. The optically active copolymer, poly[(oxycarbonyloxy)‐1‐cyclohexylethylene], was hydrolyzed and the epoxide was transformed into the form 1,2‐bis(trimethylsilyloxy)‐1‐cyclohexylethane (2). From the determination of optical activity of this ether, it is concluded that the ring opening of 1 in the copolymerization takes place predominantly at the methylene‐oxygen linkage.
Synthesis of new monomers by addition reactions of diethylamine to 1,4‐divinylbenzene catalyzed by lithium diethylamide
Authors: Tsuruta Teiji , Narita Tadashi , Nitadori Yoshiaki , Irie Tadashi
Published: February 2006

Addition reactions of diethylamine onto 1,4‐divinylbenzene (DVB) catalyzed by lithium diethylamide were examined to find a synthetic route to a group of new monomers possessing dialkylamino substituents, which is expected to be a starting material for biomedical polymers such as ionic polymer complexes, polycations, and others. It was found that 1‐(2‐diethylaminoethyl)‐4‐vinylbenzene (1) and 1,4‐bis(2‐diethylaminoethyl)‐benzene (2) can be prepared selectively, because the rate of the first step of the addition reaction was twenty times as large as that of the second step. Results of kinetic studies on the addition reactions towards DVB are discussed with the aid of 13C NMR data and compared with other p‐vinylbenzene derivatives.
Self‐crosslinkable polymers, 2. High pressure copolymerization of 2,3‐epoxy‐1‐propyl methacrylate with 2‐vinyl‐5‐ethylpyridine
Authors: Tanaka Yoshio , Atsukawa Morishige , Shimura Yukio , Okada Akira , Sakuraba Hideki , Sakata Tokuji
Published: February 2006

2,2′‐Azoisobutyronitrile‐initiated copolymerization of 2,3‐epoxy‐1‐propyl methacrylate (1) (M1) with 5‐ethyl‐2‐vinyl‐pyridine (2) (M2) was studied in tetrahydrofuran at 60°C under high pressure up to 15 kbar. Under pressure, soluble linear polymers with pendant epoxy and pyridyl groups were obtained and can be used as self‐curable resins. The monomer reactivity ratios, r1 and r2, became larger with increasing pressure (r1, r2, and pressure given): 0,60, 0,64 at 2 kbar; 0,64, 0,66 at 4 kbar; 0,72, 0,69 at 7 kbar; 0,78, 0,72 at 10 kbar; 0,87, 0,76 at 13 kbar; 0,91, 0,80 at 15 kbar. Therefore, the change of activation volume of the chain propagation, ΔV, may vary from one type of propagation step to another. The intrinsic viscosities of the copolymers were found in tetrahydrofuran at 30°C to be 0,26 to 1,35 and to be dependent upon the copolymer composition and the pressure. These copolymers were amorphous, had no clear melting points and became insoluble crosslinked polymers under heating without further addition of any curing agents.
1H NMR‐spektroskopische Untersuchungen zur Strukturaufklärung von Oligo(hydroxy‐5‐nitro‐1,3‐phenylen)methylen Verbindungen
Authors: Deveaux Jürgen , Böhmer Volker
Published: February 2006

Die 1H NMR‐Spektren von 51 Oligo(hydroxy‐5‐nitro‐1,3‐phenylen)methylen Verbindungen (17 Zwei‐, 18 Drei‐, 14 Vier‐ und 2 Fünfkernverbindungen) wurden in Pyridin als Lösungsmittel aufgenommen. Bei Verbindungen mit ortho‐Nitrophenolbausteinen zeigten die Signale für die Protonen der Methyl‐ bzw. Methylengruppen in allen Fällen charakteristische chemische Verschiebungen δ, so daß eine eindeutige Unterscheidung zwischen Methylgruppen in para‐ (δ=2,09−2,15 p.p.m.) und ortho‐Stellung (δ=2,22−2,28 p.p.m.) zur phenolischen Hydroxyl‐Gruppe, sowie zwischen para‐para‐ (δ=3,77−3,97 p.p.m.), ortho‐para‐ (δ=4,02−4,12 p.p.m.) und ortho‐ortho‐Methylenbrücken (δ=4,21−4,32 p.p.m.) möglich war. Bei Verbindungen mit para‐Nitrophenolbausteinen lagen die chemischen Verschiebungen entsprechender Methyl‐ oder Methylengruppen dagegen in einem weiteren Bereich. Am Beispiel von zwei Zweikernverbindungen wurde die Abhängigkeit der chemischen Verschiebung von der Pyridinkonzentration in Benzol untersucht.
Incréments d'indice de réfraction de polymères en solution: Étude des lois de mélange. Influence de la masse moléculaire et de la structure
Authors: Candau Françoise , Dufour Claude , François Jeanne
Published: February 2006

Nous étudions la variation de l'incrément d'indice de réfraction (dn/dc) avec la masse moléculaire et la structure pour des séries de polystyrènes linéaires et ramifiés parfaitement définis en solution dans le benzène.

Une étude réalisée dans le cadre des théories de mélange de Lorenz‐Lorentz et d'Onsager‐Böttcher nous a permis de montrer que:

Au‐dessous d'une masse moléculaire critique de l'ordre de 2.104, la variation linéaire dn/dc=f(1/Mn)s'explique entièrement par l'influence des hétérogénéités chimiques contenues dans la chaǐne (groupements terminaux, noeuds de ramification, etc.).

Les lois de mélange ne tiennent pas compte des interactions spécifiques polymère‐solvant et ne sont pas parfaitement rigoureuses.

Les variations de (dn/dc) et du volume spécifique partiel du polymère, v̄p, déjà observées pour des masses moléculaires supérieures à 2·104 s'accompagnent d'une variation de la réfractivité spécifique partielle. Nous relions ces effets à l'influence de la densité en segments à l'intérieur de la pelote linéaire ou ramifiée.

Une série homologue de polyoxyéthylène‐glycols (α‐hydro‐ω‐hydroxypoly(oxyéthylène)s) dans le benzène présente le měme comportement.
Cationic polymerization of cyclic sulfides, 6. Polymerization of propylene sulfide with different initiators
Authors: van Ooteghem Daniël , Goethals Eric J.
Published: February 2006

The kinetics of the cationic ring‐opening polymerization of propylene sulfide initiated with different initiators has been investigated and the results were compared with those obtained with triethyloxonium tetrafluoroborate as described in a previous paper. With triethyloxonium hexafluorophosphate, the polymerization showed the same characteristics, that is: an initial very fast non‐stationary stage A is followed by a much slower stage B which leads to quantitative conversion. With triethyloxonium hexachloroantimonate, the B‐stage stopped at limited conversions which was attributed to a sulfonium ion‐destroying termination reaction between the growing species and the SbCl anion to give an alkylchloride and SbCl5. Perchloric acid gives a polymerization which is analogous to the oxonium tetrafluoroborate initiated polymerizations which indicates that perchloric acid also gives a rapid and quantitative initiation reaction. Methyl fluorosulfonate on the contrary is a slow initiator. In the polymerization with boron trifluoride etherate, water acts as a co‐initiator and the maximum activity is reached at a ratio H2O/BF3OEt2 equal to 0,5. All polymerizations, with the exception of that initiated with triethyloxonium hexachloroantimonate, are of the dormant type and the polymers slowly degrade to form a mixture of low molecular weight polymer and cyclic oligomers, mainly tetramer.
Pair distribution function and pair potential of lattice model chains under theta conditions, 2. Theoretical approach
Authors: Olaj Oskar Friedrich
Published: February 2006

A general expression for the pair potential U and the pair distribution function G for an isolated pair of coiled unbranched macromolecules is derived with special reference to the Θ‐state, using a sort of “square well” potential for the description of segment‐segment interaction. Contrary to former treatments allowance has been made for the fact that at least those segment‐segment interactions which are not of hard sphere character occur at a finite contact distance δ. The “contact sites”, i.e. the locations which–in order to produce this type of interaction–have to be occupied by segments of the second chain of the pair, are shown to obey a broader distribution around the center of gravity of the first chain than its segments themselves. As a consequence the hard sphere (repulsive) and the non‐hard sphere (for the Θ‐state necessarily attractive) interactions between the two chains show a different dependence on the distance R between the centers of mass of the two chains, leading to expressions for U and G—well consistent with numerical Monte Carlo estimates‐which have the general form

and

respectively, with a always exceeding a′ and for the Θ‐state A>A′. All these parameters are well defined in terms of the model used.
Processing and classification of protein mass spectra
Authors: Hilario Melanie , Kalousis Alexandros , Pellegrini Christian , Müller Markus
Published: February 2006

Among the many applications of mass spectrometry, biomarker pattern discovery from protein mass spectra has aroused considerable interest in the past few years. While research efforts have raised hopes of early and less invasive diagnosis, they have also brought to light the many issues to be tackled before mass‐spectra‐based proteomic patterns become routine clinical tools. Known issues cover the entire pipeline leading from sample collection through mass spectrometry analytics to biomarker pattern extraction, validation, and interpretation. This study focuses on the data‐analytical phase, which takes as input mass spectra of biological specimens and discovers patterns of peak masses and intensities that discriminate between different pathological states. We survey current work and investigate computational issues concerning the different stages of the knowledge discovery process: exploratory analysis, quality control, and diverse transforms of mass spectra, followed by further dimensionality reduction, classification, and model evaluation. We conclude after a brief discussion of the critical biomedical task of analyzing discovered discriminatory patterns to identify their component proteins as well as interpret and validate their biological implications. © 2006 Wiley Periodicals, Inc., Mass Spec Rev 25:409–449, 2006
Mass spectrometry and natural variations of iron isotopes
Authors: Dauphas Nicolas , Rouxel Olivier
Published: February 2006

An Erratum has been published for this article in Mass Spectrometry Reviews 25: 831–832, 2006.

Although the processes that govern iron isotope variations in nature are just beginning to be understood, multiple studies attest of the virtue of this system to solve important problems in geosciences and biology. In this article, we review recent advances in the geochemistry, cosmochemistry, and biochemistry of iron isotopes. In Section 2, we briefly address the question of the nucleosynthesis of Fe isotopes. In Section 3, we describe the different methods for purifying Fe and analyzing its isotopic composition. The methods of SIMS, RIMS, and TIMS are presented but more weight is given to measurements by MC‐ICPMS. In Section 4, the isotope anomalies measured in extraterrestrial material are briefly discussed. In Section 5, we show how high temperature processes like evaporation, condensation, diffusion, reduction, and phase partitioning can affect Fe isotopic composition. In Section 6, the various low temperature processes causing Fe isotopic fractionation are presented. These involve aqueous and biologic systems. © 2006 Wiley Periodicals, Inc., Mass Spec Rev 25:515–550, 2006
Investigation of molecular interaction within biological macromolecular complexes by mass spectrometry
Authors: Akashi Satoko
Published: February 2006

The advent of electrospray ionization (ESI) and matrix‐assisted laser desorption ionization (MALDI) has accelerated structural studies of biological macromolecular complexes. At present, mass spectrometry can provide accurate mass values not only of individual biological macromolecules but also of their assemblies. Furthermore, it can also give information on the interface sites of the biological macromolecular complexes. The present article focuses on the role of mass spectrometry in the investigation of biological molecular interactions, such as protein–protein, protein–DNA, and protein–ligand interactions, which play essential roles in various biological events. © 2006 Wiley Periodicals, Inc.
Scattering of elastic waves in a perturbed isotropic half space with a free boundary. The limiting absorption principle
Authors: Dermenjian Yves , Guillot Jean‐Claude
Published: February 2006

In this article we consider the self‐adjoint operator governing the propagation of elastic waves in a perturbed isotropic half space with a free boundary condition. We prove the limiting absorption principle in appropriate Hilbert spaces for this operator. We also prove decreasing properties for the eigenfunctions associated with strictly positive eigenvalues of this operator.

The proofs are based on the limiting absorption principle for the self‐adjoint operator governing the propagation of elastic waves in a homogeneous isotropic half space with a free boundary and on the so called division theorem for it. Both perturbations of R+2 ={(x1, x2) ϵ R2; x2 > 0} and R+2 = {(x1, x2, x3) ϵ R3; x3 > 0} are considered.
Uniqueness for structural phase transitions in shape memory alloys
Authors: Hoffmann K.‐H. , Songmu Zheng
Published: February 2006

The non‐linear coupled equations arising from alloy mechanism

have two important features: a may take negative values and c may be degenerate.

The local existence has been proved in Reference 1, but the uniqueness was open. In this paper the uniqueness is proved. For a discussion of the physical model and for the justifications of the detailed technical assumptions to be made, we refer to Reference 1.
The optimization of directivity and signal‐to‐noise ratio of an arbitrary antenna array
Authors: Kirsch Andreas , Wilde Peter , Roach G.F.
Published: February 2006

The authors consider the optimization of the signal‐to‐noise ratio of an arbitrary cylindrical antenna array. Existence of an optimal solution and convergence of finite‐dimensional approximations is shown. The necessary optimality conditions are used to compute optimal solutions for some numerical examples.
CFD state‐of‐the art in the U.S.S.R.
Authors: Belotserkovskii O. M.
Published: February 2006

This survey paper is devoted to the description of numerical methods for modern problems of computational fluid dynamics (CFD). The problems of steady and unsteady aerodynamic flows, different transition turbulent regimes and motion around complex shape bodies (aircraft as a whole) are investigated. These approaches sharply reduce the level of demand on computer resources.
Generation, optimization and adaptation of multiblock grids around complex configurations in computational fluid dynamics
Authors: Jacquotte Olivier‐Pierre
Published: February 2006

We present a method that has been developed for the construction of grids suitable for a large class of Computational Fluid Dynamics (CFD) solvers. Three independent steps are considered: a multidomain generation, an optimization and an adaptation. The first step handles the complexity of the three‐dimensional domain to be meshed and is able to perform an algebraic construction of the grid points within a multidomain topology; any decomposition can be considered and analysed by the algorithm. The second step is able to optimize a mesh with respect to a quality measure defined in terms of cell deformation; a conjugate gradient algorithm drives the nodes up to an equilibrium position that realizes the minimum of a mesh energy quantity. The final step handles the physics of the problem and moves the nodes in order to refine the mesh where anything of interest takes place, while preserving its good metric quality. The three steps have been implemented independently and successfully, as shown by the examples presented.
Time marching integral equation method for unsteady transonic flows around airfoils
Authors: Su Jicaho
Published: February 2006

A time marching integral equation method has been proposed here which does not have the limitation of the time linearized integral equation method in that the latter method can not satisfactorily simulate the shock wave motions. Firstly, a model problem–one dimensional initial and boundary value wave problem is treated to clarify the basic idea of the new method. Then the method is implemented for two dimensional unsteady transonic flow problems. The introduction of the concept of a quasi‐velocity‐potential simplifies the time marching integral equations and the treatment of trailing vortex sheet condition. The numerical calculations show that the method is reasonable and reliable.
Numerical simulation of three‐dimensional supersonic flow around aerodynamic configurations
Authors: Chushkin P. I. , Voskresensky G. P.
Published: February 2006

The present report deals with many applications of different numerical methods to calculations of three‐dimensional stationary supersonic flows around aerodynamic configurations. Both an inviscid non‐heat‐conducting perfect gas and a real high‐temperature gas with physical‐chemical processes are considered. The results of some investigations carried out during recent years in the U.S.S.R. are reviewed. A brief description of applicable numerical methods is presented. A number of results are discussed both for separate parts of a flying vehicle and for whole configurations. Some gasdynamic effects, and aerodynamic and thermal characteristics are analysed. Among the aerodynamic elements we consider pointed and blunted nose parts of configurations, air intakes, wing and stabilizers. Also more complicated cases are considered such as compound aerodynamic objects and configurations modelling different kinds of whole flying vehicles (missile, aircraft, spacecraft).
Improving the convergence rate of the Petrov‐Galerkin techniques for the solution of transonic and supersonic flows
Authors: Baumann C. E. , Storti M. A. , Idelsohn S. R.
Published: February 2006

This paper report progress on a technique to accelerate the convergence to steady solutions when the streamline‐upwind/Petrov‐Galerkin (SUPG) technique is used. Both the description of a SUPG formulation and the documentation of the development of a code for the finite element solution of transonic and supersonic flows are reported. The aim of this work is to present a formulation to be able to treat domains of any configuration and to use the appropriate physical boundary conditions, which are the major stumbling blocks of the finite difference schemes, together with an appropriate convergence rate to the steady solution.

The implemented code has the following features: the Hughes' SUPG‐type formulation with an oscillation‐free shock‐capturing operator, adaptive refinement, explicit integration with local time‐step and hourglassing control. An automatic scheme for dealing with slip boundary conditions and a boundary‐augmented lumped mass matrix for speeding up convergence.

It is shown that the velocities at which the error is absorbed in and ejected from the domain (that is damping and group velocities respectively) are strongly affected by the time step used, and that damping gives an O(N2) algorithm contrasting with the O(N) one given by absorption at the boundaries. Nonetheless, the absorbing effect is very low when very different eigenvalues are present, such as in the transonic case, because the stability condition imposes a too slow group velocity for the smaller eigenvalues. To overcome this drawback we present a new mass matrix that provides us with a scheme having the highest group velocity attainable in all the components.

In Section 1 we will describe briefly the theoretical background of the SUPG formulation. In Section 2 it is described how the foregoing formulation was used in the finite element code and which are the appropriate boundary conditions to be used. Finally in Section 3 we will show some results obtained with this code.
Numerical simulation of the gas flow in a circuit‐breaker
Authors: Reggio M. , Trépanier J. Y. , Zhang H. , Camarero R.
Published: February 2006

A computational methodology for the solution of unsteady two‐dimensional/axisymmetric Euler equations within geometries with moving boundaries is presented. The flow simulation is carried out by applying a finite‐volume method which makes use of a Lagrangian‐Eulerian version of Roe's approximate Riemann solver. The domain discretization is handled via unstructured triangular grids. Grid adaptation is applied on the basis of geometric and physical requirements. The importance of the implicit treatment of the space conservation laws, based on geometric analysis, is evoked. The procedure for reconstructing Roe's method for moving meshes is described and validated. Finally, the ability of the method for the prediction of the transient flow in a circuit‐breaker during its opening phase is illustrated.
Transient natural convection from a horizontal cylinder confined between vertical walls—a finite element solution
Authors: Sadeghipour M. Sadegh , Hannani S. Kazemzadeh
Published: February 2006

A general finite element computer code is developed for transient two dimensional natural convection heat transfer in a laminar regime. This code is used to study heat transfer from a horizontal isothermal cylinder confined between two vertical adiabatic walls. Results are presented for Ra = 1000, Pr = 0.7, and for different wall spacing to cylinder diameter ratios. The time variations of the local and average Nusselt numbers along with some transient and steady state velocity and temperature fields are demonstrated. The steady state results predict the existence of an optimum wall distance for the maximum average Nusselt number. The steady state and the transient Nusselt numbers are compared with the available experimental or theoretical results for a few cases. Their agreement is very good.
Histological findings in Morton's metatarsalgia
Authors: Meachim G. , Abberton M. J.
Published: February 2006

MORTON'S metatarsalgia is a distinctive clinical condition characterised by paroxysmal, lancinating pain in the forefoot in the region of the metatarso‐phalangeal joints. The sensation is often described as that of (walking on a hot pebble). It is worse on walking, and typically eased by rest and by taking off the shoe. Manipulating the foot also sometimes eases the pain: it can cause sudden relief, the pain being replaced by a dull burning sensation.
Metastasising gliomas in young subjects
Authors: Eade O. E. , Urich H.
Published: February 2006

ALTHOUGH formation of metastases via the cerebrospinal fluid (CSF) is well recognised with medulloblastomas, this mode of spread is rare amongst other intracranial tumours. Metastasis outside the central nervous system was, for many years, thought never to occur (Bailey and Cushing, 1926). Several cases have now been described and were reviewed by Glasauer and Yuan (1963); we are presenting a further series of five gliomas spreading through the cerebrospinal fluid, with distant metastases in two instances, in an attempt to define their histological features and other circumstances that favour this mode of spread.
Aspergillus fumigatus endocarditis of an aortic homo‐graft with aneurysm of the ascending aorta
Authors: Doshi Rasikbala
Published: February 2006

Fungal endocarditis is an uncommon complication of cardiac surgery. Candida endocarditis following open heart surgery was first reported by Koelle and Pastor (1956) and since then 24 cases have been recorded. Nineteen cases were reviewed by McConnell and Roberts (1967) and three cases of their own were added. Two more cases have been reported since, one by Newsome, Lea and Russell Rees (1967) and the other by Kahn, Kane and Dean (1968).

The fungi isolated from these 24 cases were Candida albicans in 14, other Candida species in seven, Aspergillus in two and Paecilomyces in one (Uys et al., 1963). The first case of Aspergillus endocarditis following open heart surgery was reported by Newman and Cordell (1964).

This paper presents a case of Aspergillus fumigatus endocarditis on an aortic valve homograft.
Simulation‐based design of sheet molding compound (SMC) compression molding
Authors: Twu Jun‐Tien , James Lee L. , Chen Shia‐Chung
Published: February 2006

The design of moding tool and molding cycle for sheet molding compounds (SMC) is often expensive and time consuming. Computer simulation of the compression molding proces is a desirable approach to reduce experimental prototypes. The focus of this work is to develop an automatic optimization scheme utilizing an earlier developed SMC plrocess simulation program which is capable of simulating material flow, heat trensfer, and curing. The proposed scheme reduces computing time by using approximate responses, instead of actual simulated responses, to perform the optimization. The automated optimization package minimizes user intervention during optimal design by creating an automatic link between the optimization and simulation routines. A 2‐level factorial design combined with regression analysis is adopted to gather and analyze computed information, and to serve as the approximation formula. Two examples are presented to test the applicability of the optimization scheme.
Random glass mat reinforced thermoplastic composities. Part VII: A statistical approach to strength
Authors: Bushko Wit C. , Stokes Vijay K.
Published: February 2006

Large macroscopic‐scale variations in the tensile moduli and tensile strengths are charcteristic of random glass mat composites (GMT). The large‐scale, point‐to‐point variations in the local stiffness is characterized by a probability density function that can be used to predict the stiffness of parts only in a statistical sense. Weibull statistics widely used for modeling the scatter in the strength of brittle materials cannot be applied to the large variations in the strength of GMTs: The macroscopic stress field in brittle materials is assumed to be deterministic, while the stress field in GMTs varies randomly on a macroscopic scale. A statistical approach for characterizing the strength of GMTs is developed by combining an empirically established strength‐modulus correlation with the statistical characterization of the tensile modulus.
Carbon fiber modified composites of tetrafluoroethylene‐ethylene copolymers
Authors: Kostov G. K. , Nikolov A. T.
Published: February 2006

Composites based on tetrafluoroethylene‐ethylene copolymers with graphitized polyacrylonitrile fibers were developed. The effect of the fiber length and concentration on the properties of the compositions was studied. Thermoactivation of the fibers was carried out and its influence on the properties of the tetrafluorethylene‐ethylene compositions was studied. Graphitized fibers possessing the higest content of oxygen‐containing functional groups thermoacttivated at 1073 K for 30 min exerted the highest reinforcing effec (∼40%). The relation between fibers finished with γ‐aminopropltriethoxysilance and theproperties of the compositions obtained was also studied. A synergetic effect on the compositions mechanical and thermal properties was observed for the modified carbon fibers, whereas the other properties remained almost the same. The additional reinforcement of the carbon compositions modified with fiber monocrystals ofalkali titanates in concentrattions from 0.5 to 5.0 Wt% strengthens the tetrafluoroethylene‐ethylene polymer matrix by increasing the dynamic modulus, hardness, and thermoresistance of the composities.
Polymerization of bisdithiafulvenes with conjugated spacers using oxidative dimerization
Authors: Naka Kensuke , Inagi Shinsuke , Murachi Yuki , Chujo Yoshiki
Published: February 2006

Novel vinylogous tetrathiafulvalene (TTF) containing polymers (13 and 14) were prepared by the oxidative dimerization polymerization of bisdithiafulvenes. The obtained polymers were soluble in common organic solvents such as CHCl3. The structures of the polymers were confirmed by 1H NMR and cyclic voltammetry analysis. The number‐average molecular weights of 13 and 14 were estimated from gel permeation chromatography to be 3600 and 3800, respectively. Through the introduction of phenylene or phenylene–vinylene spacers, distortion between dialkoxybenzene and vinylogous TTF units was effectively prevented according to ultraviolet–visible analysis. The polymers exhibited a strong electron‐donating property investigated by cyclic voltammetry analysis. Chemical doping by CF3SO3H gave doped polymers having a cationic radical and a dication of a vinylogous TTF unit. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2027–2033, 2006
Gas solubility of carbon dioxide in poly(lactic acid) at high pressures
Authors: Oliveira N. S. , Dorgan J. , Coutinho J. A. P. , Ferreira A. , Daridon J. L. , Marrucho I. M.
Published: February 2006

The sorption of carbon dioxide in poly(lactic acid) (PLA) was studied by quartz crystal microbalance at high pressures. To address the effect of the D isomer present in the polymer on the gas sorption, measurements were performed in PLA with two different L:D contents, 80:20 and 98:2. New data for the solubility of carbon dioxide in PLA 80:20 and PLA 98:2 over a temperature range from 303.2 to 323.2 K and up to 5 MPa are presented. The results obtained were correlated with the dual‐mode sorption model and the Flory‐Huggins equation. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1010–1019, 2006
Prediction of solvent diffusion coefficient in amorphous polymers based on an equation‐of‐state
Authors: Lv Hong‐Ling , Wang Bao‐Guo
Published: February 2006

This study develops a modified free‐volume model to predict solvent diffusion coefficients in amorphous polymers by combining the Vrentas–Duda model with the Simha–Somcynsky (S‐S) equation‐of‐state (EOS), and all the original parameters can be used in the modified model. The free volume of the polymer is estimated from the S‐S EOS together with the Williams‐Landel‐Ferry fractional free volume, and the complex process of determining polymer free‐volume parameters in the Vrentas–Duda model and measuring polymer viscoelasticity can be avoided. Moreover, the modified model includes the influence of not only temperature but also pressure on solvent diffusivity. Three common polymers and four solvents are employed to demonstrate the predictions of the modified model. The calculation results are generally consistent with the experimental values. It is reasonable to expect that the modified free‐volume model will become a useful tool in polymer process development. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1000–1009, 2006
Effect of glass bead packing on the fibrillation of liquid‐crystalline polymer in polycarbonate
Authors: Chen Peng , Chen Jun , Zhang Baoqing , Zhang Jun , He Jiasong
Published: February 2006

Polycarbonate (PC) was melt blended with small amount of liquid‐crystalline polymer (LCP) and various contents of glass beads (GB) having different diameters. The rheological measurements indicated that the GB addition increased the viscosity ratio and seemed unfavorable to the LCP fibrillation. However, the morphological observation showed that the LCP fibrillation was promoted by the GB addition and varied with the GB packing. With the increased GB packing by increasing the GB content and/or decreasing the GB diameter, LCP deformed from spheres and ellipsoids into stretched ellipsoids at lower shear rates and into long fibrils at higher shear rates. Although higher content of smaller GB jammed into the larger LCP droplets and inhibited the LCP fibrillation, very long LCP fibrils formed at higher shear rates at a high enough packing of GB. The relationship between GB packing and LCP fibrillation revealed two kinds of hydrodynamic effects of GB promoting the LCP fibrillation: at lower GB packing, the shear flow was enhanced by the high local shear between GB, in quantity; and for a high enough GB packing, the shear flow was changed, in quality, into elongational flow, which was more effective for the LCP fibrillation. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1020–1030, 2006
Predicting the three‐dimensional structure of human P‐glycoprotein in absence of ATP by computational techniques embodying crosslinking data: Insight into the mechanism of ligand migration and binding sites
Authors: Vandevuer Stéphane , Van Bambeke Françoise , Tulkens Paul M. , Prévost Martine
Published: February 2006

P‐glycoprotein is a membrane protein involved in the phenomenon of multidrug resistance. Its activity and transport function have been largely characterized by various biochemical studies and a low‐resolution image has been obtained by electron microscopy. Obtaining a high‐resolution structure is, however, still remote due to the inherent difficulties in the experimental determination of membrane protein structures. We present here a three‐dimensional (3D) atomic model of P‐glycoprotein in absence of ATP. This model was obtained using a combination of computational techniques including comparative modeling and rigid body dynamics simulations that embody all available cysteine disulfide crosslinking data characterizing the whole protein in absence of ATP. The model features rather well most of the experimental interresidue distances derived both in the transmembrane domains and in the nucleotide binding domains. The model is also in good agreement with electron microscopy data, particularly in terms of size and topology. It features a large cavity detected in the protein core into which seven ligands were successfully docked. Their predicted affinity correlates well with experimental values. Locations of docked ligands compare favorably with those suggested by cysteine‐scanning data. The finding of different positions both for a single ligand and for different ligands corroborates the experimental evidence indicating the existence of multiple drug binding sites. The interactions identified between P‐glycoprotein and the docked ligands reveal that different types of interactions such as H‐bonds, π–π and cation–π interactions occur in agreement with a recently proposed pharmacophore model of P‐glycoprotein ligands. Furthermore, the model also displays a lateral opening located in the transmembrane domains connecting the lipid bilayer to the central cavity. This feature supports rather well the commonly admitted mechanism of substrate uptake from the lipid bilayer. We propose that this 3D model may be an important tool to understand the structure–function relationship of P‐glycoprotein. Proteins 2006. © 2006 Wiley‐Liss, Inc.
In vitro testing of teratogenic agents using mammalian embryos
Authors: Kochhar D. M.
Published: February 2006

The need for efficient methods to screen new chemicals, drugs, and environmental pollutants for their teratogenic activity is obvious. The method currently available, ie, pregnant‐animal testing, is of considerable value but there are certain drawbacks which prevent reliance on this method alone as the predictive device. Nutritional state of the dam, variability in the developmental age of embryos from litter to litter and even within the same litter, metabolic differences between species, placental function, and a host of other factors must be taken into account before data obtained from animal testing can be logically extrapolated to human situation. Many of these variables are either eliminated altogether or at least can be controlled by the use of tissue culture techniques. After surveying a variety of in vitro systems, it is our opinion that organ culture, whole embryo culture, and a combination of the two offer at present the best potential for screening of suspected teratogens. These culture techniques provide a much better simulation of in vivo situations than isolated cells grown as monolayers. Among other advantages, these procedures allow one to exercise control over the effective concentration of the suspected teratogen to which an embryo is exposed and also the duration of this exposure. Since maternal metabolism or modification of the drug is routinely eliminated in these experiments, there is a need for exploring the use of drug‐metabolizing preparations as additives to the culture medium. The choice of limb bud in the screening system is promising since during its development, the limb progresses through a succession of embryonic processes that are generally relevant to other organ systems as well. Hence, such a screening system may not only predict teratogenicity but also provide insight into the mechanisms by which a test chemical is teratogenic.
A cell culture assay for tumor‐promoter‐dependent progression toward neoplastic phenotype: Detection of tumor promoters and promotion inhibitors
Authors: Colburn Nancy H. , Koehler Barbara A. , Nelson Katherine J.
Published: February 2006

Mouse epidermal cell lines have been identified which respond to tumor‐promoting (but not nonpromoting) phorbol esters with an irreversible shift in anchorage independence, an in vitro marker of neoplastic phenotype. This response may be analogous to a later stage of tumor promotion in vivo. The shift occurs at TPA concentrations as low as 0.1 ng/ml (1.6 × 10−10 M). The specificity of the soft agar growth response is not limited to phorbol esters but extends to nonphorbol plant diterpenes such as mezerein, to detergents, to polycyclic hydrocarbons present in cigarette smoke, and to some growth factors. All of the above classes of compounds have been previously shown to have tumor‐promoting and/or cocarcinogenic activity in mouse skin in vivo. Clonal heterogeneity for TPA responsiveness has been found. Clones which were highly responsive to phorbol esters were also highly responsive to other classes of promoters, indicating their usefulness both for promoter detection and mechanism studies. The anchorage‐independence response to TPA was inhibited by a series of retinoids whose activity paralleled that for inhibiting tumor promotion in vivo. Both retinoid inhibition and clonal heterogeneity for promoter response are being utilized to study determinants of preneoplastic progression.
Carcinogen–DNA interaction: Differential effects of distamycin‐A and spermine on the formation of 7‐methylguanine in DNA by N‐methyl‐N‐nitrosourea, methylmethanesulfonate, and dimethylsulfate
Authors: Rajalakshmi S. , Rao Prema M. , Sarma D. S. R.
Published: February 2006

Experiments were designed to determine whether DNA conformation and sequence play any role in its methylation by N‐methyl‐N‐nitrosourea, methylmethanesulfonate, and dimethylsulfate, agents that are known to methylate DNA by different mechanisms but yield 7‐methylguanine as the major product. The approach taken was to bind ligands to DNA that interact with it stereospecifically and to study their effect on the formation of 7‐ methylguanine by the three methylating agents. The results indicate that both distamycin A and spermine shielded the formation of 7‐methylguanine in vitro in rat liver DNA by N‐methyl‐N‐nitrosourea but not by methylmethane‐sulfonate or dimethylsulfate; they did not, however, protect 2‐deoxyguanylic acid against methylation by N‐methyl‐N‐nitrosourea. Based on the mechanism by which the methylating agents and the ligands react with DNA, these results are interpreted to suggest that (1) guanines methylatable at the N‐7 position by N‐methyl‐N‐nitrosourea are located at, or close to, the binding sites of the ligands, probably the A‐T‐rich regions, and those methylatable by methyl‐ methanesulfonate and dimethylsulfate are distal to these regions, and/or (2) the conformation DNA assumes in the presence of distamycin A or spermine permits methylation by methylmethanesulfonate and dimethylsulfate but not by N‐methyl‐N‐nitrosourea. The study implicates DNA structure and/or its sequences in carcinogen‐DNA interaction.
Mutagenic activation of an antischistosomal drug by enteric streptococcus sps in vitro and in vivo
Authors: Molineaux C. J. , Batzinger R. P. , Schmidt W. , Bueding E.
Published: February 2006

Previous studies have shown that a new antischistosomal drug, 4‐isothiocyano‐4′‐nitro diphenylamine (CGP 4540, amoscanate), is not mutagenic in vitro, but the urines of animals treated with this drug have mutagenic activity. Mutagenicity can be eliminated by coadministration of some antibacterial agents and is not demonstrable in germ‐free animals. The present study describes attempts to isolate and identify intestinal microorganisms responsible for the mutagenic activation of amoscanate. Streptococcus equinus, isolated from the intestinal tract of mice, as well as some other species of Streptococcus, were found to produce mutagenic activation of amoscanate when introduced into animals pretreated with antibacterial agents. Similarly, incubation of these strains with amoscanate in vitro resulted in the formation of a mutagenic product.
Estimation of creatine phosphokinase and hydroxyproline in the developing limb: Its use in evaluating the effect of teratogens on myogenesis and chondrogenesis
Authors: Kwasigroch T. E. , Neubert D.
Published: February 2006

Forelimbs of mouse fetuses were examined for tissue‐specific, drug‐induced alterations in their biochemical composition. The activity of the enzyme creatine phosphokinase (CPK; to estimate myogenesis) and the content of hydroxyproline (HP; to estimate chondrogenesis) were compared in homogenates of control and treated mouse‐fetus forelimbs on day 14 of gestation. In addition, the content of DNA, RNA, and protein was also measured. Injection of 6‐aminonicotinamide (6‐AN) (15 mg/kg) on day 10 resulted in an overall growth retardation in day 14 fetuses and all biochemical parameters tested were reduced. The ratio of HP:CPK was unaffected by 6‐AN treatment. Retinoic acid (vitamin A acid; 100 mg/kg), administered to pregnant female mice on day 10, produced severe forelimb defects and resulted in a significant reduction in day 14 forelimb HP and RNA content, without altering CPK, DNA, or protein; thus, the HP:CPK ratio was decreased. These results indicated that (1) 6‐AN nonspecifically retards growth and cytodifferentiation in limbs; (2) retinoic acid inhibits synthesis of collagen and RNA; (3) retinoic acid has a differential effect upon chondrogenic and myogenic tissues of the limb, and (4) the comparison of HP content and CPK activity in tissue homogenates is an acceptable method of evaluating teratogenic compounds for selective effects.