bluuebunny/crossref_metadata_2025 huggingface dataset:
Sensitivity Analysis of Human Leg Metabolical Costs
Authors: Ackermann Marko , Schiehlen Werner
Published: December 2005

The human walking is characterized by skeletal dynamics and muscle excitation patterns minimizing the metabolical energy. This criterion is applied to assess the performance of lower limb prosthetic devices, and to evaluate therapies for patients presenting gait disorders. It is desirable, therefore, to dispose models of the human normal and pathological gaits capable of estimating the metabolical energy expenditure.

For the swing phase of normal and pathological gaits a musculoskeletal model of the lower limb is presented to estimate metabolical energy expenditure. The mechanical model has three degrees of freedom and is actuated by eight Hill‐type muscle units, and the model for the metabolical costs is adopted from literature. In this paper a combination of inverse and direct dynamics is used, and a sensitivity analysis of the dynamical behavior and the corresponding metabolical costs estimations with respect to parametrized neural excitations is performed. The leg motions are based on experiments in a gait analysis laboratory. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimierung der Kontaktgeometrie einer Ringplattform
Authors: Bestle Dieter
Published: December 2005

Neuere Verfahren der Schornsteinbeseitigung in Kraftwerken verwenden Plattformen mit vorgespannten Ringseilen und kraftschlüssigem Kontakt. Die geometrische Auslegung der angepressten Pratzen und der Ringseilform lässt sich als Mehrkriterien‐ bzw. Min‐Max‐Optimierungsproblem formulieren und lösen. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ein O(n) Verfahren mit Kontaktbedingungen zur Modellierung einer zweibeinigen Laufmaschine
Authors: Gattringer Hubert , Bremer Hartmut
Published: December 2005

Bei der dynamischen Modellierung von baumstrukturierten Mehrkörpersystemen (starr oder elastisch), wie das bei Laufmaschinen der Fall ist, entstehen hochdimensionale Bewegungsgleichungen. Der Rechenaufwand zur Invertierung der Massenmatrix und somit zur numerischen Lösung explodiert förmlich mit der kubischen Ordnung der Freiheitsgrade. Ausgehend von der Projektionsgleichung, einer synthetischen Methode zur Berechnung der Bewegungsgleichung, kann ein O(n) Verfahren hergeleitet werden. Dabei werden die Einzelkörper zu definierten Subsytemen (immer wiederkehrende Baugruppen) zusammengefasst, um das Problem geeignet zu strukturieren. Über die den Subsystemen zugeordneten beschreibenden Geschwindigkeiten erhält man gut interpretierbare Zwischenergebnisse. Die in dieser Arbeit vorgestellte zweibeinige Laufmaschine besteht aus 28 Starrkörpern , wobei jeweils 2 Körper (Motor und Arm) zu einem Subsystem zusammengefasst sind. Für die Berechnung der Beschleunigung müssen nur quadratische Matrizen vom Rang 2 (Anzahl der Relativfreiheitsgrade pro Subsystem) invertiert werden. Bei der Modellierung des Gehens werden Bindungen mit dem zweiten Fuß immer wieder geöffnet und geschlossen. Dies wird mithilfe einer Kontaktkraft (Lagrangescher Parameter) implementiert. Die Invertierung der Gesamtmassenmatrix kann für die Berechnung des Lagrangeschen Parameters mit einer Erweiterung des O(n) Verfahrens ebenfalls umgangen werden. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unkontrollierbare Bewegungen ebener Mechanismen mit Gelenkspiel
Authors: Hofmeister Adolf , Sextro Walter , Röschel Otto
Published: December 2005

In dieser Arbeit wird ein analytisches Berechnungsverfahren vorgestellt, mit dem der gesamte Positions‐ und Orientierungsraum (ErrorWorkspace) ebener Mechanismen mit spielbehafteten Gelenken kinematisch beschrieben bzw. dargestellt werden kann. Für die Berechnung wird der gesamte Positions‐ und Orientierungsraum im Kinematischen Bildraum dargestellt, wobei auf besondere Merkmale eingegangen wird. Der ErrorWorkspace, der mit Hilfe des Berechnungsverfahren bestimmt wird, wird an einem Koppelgetriebe, an einem Filmgreifergetriebe und an einem Double‐rocker four‐bar mechanism mit Kurbelantrieb dargestellt und analysiert. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The discrete null space method for constrained mechanical systems in nonlinear structural and multibody dynamics
Authors: Leyendecker S. , Betsch P. , Steinmann P.
Published: December 2005

Corresponding to d'Alemberts principle in classical mechanics, the discrete null space method developed in [1] provides an energy‐momentum conserving time stepping scheme for conservative finite‐dimensional dynamical systems subject to constraints. The elimination of the Lagrange multipliers from the temporal discrete system leads to a reduced number of unknowns and to an improved condition number during the iterative solution of the nonlinear system. External and internal constraints are fulfilled likewise at the time nodes, wherefore the discrete null space method is particularly suited for the treatment of elastic multibody systems in structural dynamics. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Troubleshooting in Studying the Behavior of Ballast Stones using Molecular Dynamic Simulation
Authors: Mircea Alina , Popp Karl
Published: December 2005

For the safety of the railways very important, beside tracks and trains, is the behavior of ballast stones. In the last years many scientists have started to investigate the behavior of the ballast stones and the parameters that influence them. In order to describe this behavior, one can choose a continuum mechanical description of the system or a discrete one. The problem with the first method is that the material parameter set depends on stone geometry, humidity and further factors. The second method (also called Molecular Dynamic Method MDS) makes possible a close‐to‐reality rendition of each ballast stone by means of numeric time step integration. We use MDS in order to built up a model for the system ballast stones ‐ track. Through our model we analyze small ballast stones range like under a magnifying glass. The ballast stones appear as polygons with a number of corners between 5 and 8, written in ellipses, and a size of 2 to maximally 6.3 cm. In the first step the model B70 has been selected for the track and the parameter of the model has been investigated. In the second step the program became more flexible and one can decide if the system consists from one track and ballast stones or from two tracks and ballast stones. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Studies Regarding the Development of Integrated Microgrippers Models Design Based on the PLM Systems
Authors: Pisla Adrian
Published: December 2005

In the paper are presented the tendencies, considerations and conclusions regarding the design, simulation, testing and development of some integrated microgripers, based or destined on the parallel kinematics by using the PLM concepts and a PLM system, in order to identify the most appropriate correlation between the factors that are leading to the final design and to the manufacturing process of the integrated microgripers. The paper is structured in three parts: introduction regarding the gripping systems tasks and evolution, the development of the applications in the miniaturization direction and the model and conclusions accomplished for the next developments. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New Algorithm for the Identification and Analysis of the Parallel Robots Singularities
Authors: Pisla Doina
Published: December 2005

The paper presents a new algorithm for the analysis of the kinematic singularities for different parallel structures using a testing stand. The derived expressions are used to superimpose graphical representations of the manipulators singularity and workspace. The analytical description of the singularity loci can be successfully used for the optimisation of the kinematic design. The derived algorithm for singularities analysis has been integrated in an already developed parallel robots simulation system, which provides an easy to read graphical representation of the singularities that enables their isolation within the working space and their avoiding in the path programming activity. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamisches Verhalten einer elektromechanisch betätigten Lamellenkupplung
Authors: Treder Marco , Woernle Christoph
Published: December 2005

Eine Alternative zur hydraulischen Betätigung automatisierter Fahrzeugkupplungen stellt die elektromechanische Betätigung dar. Ein Funktionsmuster eines elektromechanischen Kupplungsaktors besteht aus einem Stellmotor, einem Untersetzungsgetriebe und einerMechanik zur Realisierung der Betätigungskraft, die auf die Kupplungslamellen wirkt. Für die Simulation des dynamischen Kupplungsverhaltens wird ein detailliertes Mehrkörpermodell entwickelt, das Modelle des elektromechanischen Aktors und der nasslaufenden Lamellenkupplung enthält. Die Betätigung der Kupplung wird durch Vorgabe unterschiedlicher Zeitfunktionen des Moments des Stellmotors realisiert. Die Simulationsergebnisse werden mit Messergebnissen verglichen. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling and application of the self‐locking phenomenon in the context of a non‐discrete impact clutch
Authors: Welge‐Luessen Tobias , Glocker Christoph
Published: December 2005

This paper describes an application of the self locking phenomenon in order to realize a non‐discrete impact clutch. It is used to generate velocity jumps in an underactuated robot manipulator. Due to control reasons the impacts have to be made possible at arbitrary times, which calls for a non‐discrete device. Different design alternatives are listed and a numerical simulation as well as a possible mechanical design of the self‐locking mechanism are presented. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effective Dynamic Material Properties of Foam‐like Microstructures
Authors: Alvermann S. , Schanz M.
Published: December 2005

The effective material parameters of a microstructured material can be found using homogenization procedures based on calculations of a Representative Volume Element (RVE) of the material. In our approach the RVE is calculated in frequency domain and inertia is taken into account, leading to a frequency dependent behavior of the RVE.With the frequency response of the RVE, effective dynamic properties of the material are calculated using an optimization procedure. Due to the frequency dependent material behavior on the microscale a viscoelastic constitutive equation is applied on the macroscale. An example calculation is presented for an auxetic 2‐D foam‐like microstructure which is modelled as a plane frame structure. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Beanspruchungsgerechte Gestaltung bei Biegebelastung
Authors: Ertz M.
Published: December 2005

Bei der Entwicklung beanspruchungsgerechter Bauteile werden oft Verfahren zur numerischen Strukturoptimierung eingesetzt. Manche Ansätze auf diesem Gebiet gehen von einem Abbau hoher Spannungen durch gezielten Materialzuwachs an hoch beanspruchten Stellen aus. Bei Biegebelastung führt dieser Ansatz aber nicht immer zum Erfolg, weil ein Materialzuwachs hier unter Umständen sogar zu einer Erhöhung der lokalen Materialbeanspruchung führen kann. Am Beispiel eines einfachen Biegebalkens lässt sich dieses Problem anschaulich darstellen. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Conservation laws for a consistent plate theory
Authors: Kienzler Reinhold , Bose Dipak K.
Published: December 2005

Within the framework of a consistent second‐order plate theory, three material conservation laws are established, which are useful to describe the energy‐release rates and the material forces connected with the change of configuration of inhomogeneities or defects within the plate. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Buckling‐Bending Problem for Circular Plate
Authors: Marko Lubomir
Published: December 2005

We consider radially symmetric deformation of a thin flat elastic circular plate of constant thickness clamped at its edge. The plate is under the action of a uniform compressive thrust along its edge in the midplane of the plate. The thrust is proportional to a real parameter λ. The plate is also subjected to a radially symmetric load, normal to its midplane. The equilibrium states of the given buckling‐bending problem are the solutions of von Kármán equations. Let λ1 < λ2 be the first and the second eigenvalue of the linearized problem. If λ ≤ λ1 the buckling‐bending problem has unique solution for any normal load. If λ ∈ (λ1, λc), where λ1 < λc < λ2 the buckling‐bending problem has one or three solutions depending on the normal load. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Asymptotic Analysis of Free‐Edge and Free‐Corner Effects in Laminate Structures
Authors: Mittelstedt Christian , Becker Wilfried
Published: December 2005

Stress fields in the vicinity of free edges and corners of composite laminates exhibit singular characteristics and may lead to premature interlaminar failure modes like delamination fracture. It is of practical interest to investigate the nature of the arising free‐edge and free‐corner stress singularities ‐ i.e. the singularity orders and modes ‐ closely. The present investigations are performed using the Boundary Finite Element Method (BFEM) which in essence is a fundamental‐solution‐less boundary element method employing standard finite element formulations. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Incompatibility Induced Nonlocal Crystal Plasticity
Authors: Becker Martin , Miehe Christian
Published: December 2005

Motivated by the fact that locally inhomogeneous elastic or plastic deformations may result in incompatibilities of the fictitious intermediate configuration a strain gradient crystal plasticity model is developed. Thereby incompatibilities can be accounted for and scale dependent material behavior, as also observed experimentally, is predictable. A nonlocal extension of existing local formulations is proposed which does not require additional boundary conditions and thus maintains the classical BVP structure. On the numerical side key developments are an extended FE‐formulation for rate‐(in)dependent strain gradient plasticity and a local FE‐formulation which bases the gradient computation on an operator split combined with a smoothing algorithm. Comparative numerical studies for classical examples proove the superior efficiency of the second approach. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local and extended models for high‐speed, dynamic loading of metals
Authors: Flatten Arnd , Svendsen Bob , Klingbeil Dietmar
Published: December 2005

The purpose of this work is to compare and contrast two different modeling approaches for high‐speed, dynamic loading of metals. A so‐called “local” model including hardening, strain‐rate hardening as well as temperature and ductile damage softening behaviour is extended by gradient plasticity. In particular, both models are compared in the context of their application to the modeling and simulation of dynamic shear‐banding in the alloy Inconel 718. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Instability prevention at the modeling of large elasto‐plastic strains under cyclic loading
Authors: Gorokhov M. Yu. , Semenov A. S. , Melnikov B. E. , Ulbricht V.
Published: December 2005

The cyclic instability phenomenon is investigated at the modeling of large elasto‐plastic strains. The possible causes of the cyclic instability and conditions ensuring cyclical stability of elasto‐plastic models are analyzed for the case of large strains. Among the possible causes of the cyclic instability the following are considered: the method of strain decomposition on elastic and plastic parts; the constitutive law for the elastic deformation (hypo‐ and hyper‐elasticity); the constitutive equation for the plastic deformation; the constitutive relation for the plastic spin; kinematic hardening law, in particular, the type of the objective rate in the generalized Prager's law. Predictions of 50 various models of the elasto‐plastic material have been compared in order to find the causes of the cyclic instability. Two test problems are considered: cyclic simple shear, combined cyclic simple shear and tension‐compression. Results of numerical experiments for the various material models are presented and discussed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Creep of Single Crystals – Modelling and Numerical Aspects
Authors: Vladimirov Ivaylo , Reese Stefanie , Eggeler Gunther
Published: December 2005

A number of constitutive models, utilizing both microstructural and/or phenomenological considerations, have been developed for the simulation of the creep behaviour of nickel‐base single crystal superalloys at elevated temperatures. In this work, emphasis is placed on the rate‐dependent single crystal plasticity model [1]. A strategy for the identification of the material parameters of the model to fit the results from experiments has been implemented. The parameter fitting methodology rests upon a two‐membered evolution strategy. In addition, a proposal is made for the extension of the Cailletaud model [1] by means of an evolution equation for a damage variable which enables the modelling of the tertiary creep stage. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Hill's Bipotential
Authors: Ban M. , Vallée C. , Lerintiu C.
Published: December 2005

A new formulation of the constitutive law of materials based on the concept of bipotential was introduced by de Saxcé. This concept is able to describe non‐associated laws and to suggest robust numerical algorithms. Materials that admit a bipotential to model their behaviour constitute the class of Implicit Standard Materials (ISM). This class contains, as a sub‐class, the Generalized Standard Materials (GSM). In this paper, we present a bipotential expressing the coaxiality of two tensors with preservation of the order of the eigenvalues. We call it Hill's bipotential. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Relaxation model of piezoelectric materials
Authors: Delibas B. , Arockiarajan A. , Seemann W.
Published: December 2005

Polarization switching inside grains is time dependent. When external applied loading is not quasi‐static, macroscopic properties of piezoelectric materials changes with the rate of loading. In this paper, a 2‐D micromechanical model is proposed in order to simulate the rate dependent properties of certain perovskite type tetragonal piezoelectric materials based on linear constitutive, nonlinear domain switching, intergranular effects and kinetics models. The material is electrically loaded with an alternating voltage of various frequencies. For the onset of domain switching, energy equation is implemented. Propagation of the domain wall during domain switching in grains is modeled by means of exponential kinetics relation after domain nucleation. Mechanical strain butterfly loops under different frequencies (0.01Hz–1Hz) are simulated. The model gives important insights into the rate dependency of the piezoelectric materials that have been observed in some experiments reported in the literature. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of polycrystalline ferroelectrics based on discrete orientation distribution functions
Authors: Kurzhöfer Ingo , Schröder Jörg , Romanowski Holger
Published: December 2005

Ferroelectric materials exhibit a spontaneous polarization, which can be reversed by an applied electric field of sufficient magnitude. The resulting nonlinearities are expressed by characteristic dielectric and butterfly hysteresis loops. These effects are correlated to the structure of the crystal and especially to the axis of spontaneous polarization in case of single crystals. We start with a representative meso scale, where the domains consist of unit cells with equal spontaneous polarization. Each domain is modeled within a coordinate invariant formulation for an assumed transversely isotropic material as presented in [10], in this context see also [8]. In this investigation we obtain the macroscopic polycrystalline quantities via a simple homogenization procedure, where discrete orientation distribution functions are used to approximate the different domains. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A fluid mechanical model for granular flow in silos
Authors: Leppert Caroline , Dinkler Dieter
Published: December 2005

Granular materials may display both solid and fluid like behaviour. For low densities and high strain rates as in avalanches or during the discharge of silos the behaviour is mainly governed by interparticle collisions. On the other hand, frictional contacts characterise the solid state which is represented within the framework of plasticity theory. A fluid like constitutive model describes granular materials when subjected to large deformations and high strain rates. It bases upon a modified viscoplastic model that is valid for both yielded and unyielded regions. The central idea is the distinction between fluid and solid regions by means of comparing actual shear stress and Coulomb yield stress. The application to the simultion of the discharge of silos shows the feasibility of the chosen method. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Aspects of the simulation of the ferroelectric hysteresis
Authors: Romanowski H. , Schröder J.
Published: December 2005

In this paper we present a thermodynamically consistent phenomenological model for an assumed transversely isotropic ferroelectric crystal. Such materials become spontaneously polarized within a certain range of temperature. On the macro scale a remanent polarization and remanent strains, due to the reorientation of the polarization vectors, are observed, if an electric field above the so‐called coercive field is applied. The goal of this work is to construct a thermodynamically consistent formulation of the electro‐mechanically coupled ceramic on a meso scale, that takes into account the orientation of the assumed transversely isotropic unit cell, see [4]. The anisotropic behavior is governed by isotropic tensor functions, which are formulated in terms of a finite set of invariants, see [3]. Considering a simple model problem we discuss the linearization of discrete weak forms, resulting from the electromechanical boundary value problem. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computation of Material Forces in Thermoplasticity Based on Alternative Smoothing Algorithms
Authors: Zimmermann Dominik , Miehe Christian
Published: December 2005

Different approaches to the computation of material forces in inelastic structures are investigated. Dissipative effects in inelastic materials are described by internal variables. The formulation of balance equations in the material space requires the computation of gradients of these internal variables. The computational evaluation of these gradients in the context of finite element simulations needs a global representation of the internal variable fields. On the one side, this request can be carried out by a global formulation that discretizes the internal variable fields in terms of nodal degrees additional to the displacements. A numerically more effective approach applies smoothing algorithms which project the internal variables of a typical local formulation from the integration points onto the nodal points. In detail, the implementation of two smoothing algorithms for the computation of material forces is dicussed. The L2–projection necessiates the solution of a system of equations on the global level. A patch recovery yields a smoothed solution from an element patch surrounding the nodal point of interest. The performance of both algorithms is compared for the material force computation in finite thermoplasticity. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
In‐situ pultrusion of urea‐formaldehyde matrix composites. II: Effect of processing variables on mechanical properties
Authors: Yen Chih‐Chao , Chen Chin‐Hsing , Lue Jun‐Yi
Published: December 2005

Unidirectional fiber reinforced urea‐formaldehyde (UF) composites have been prepared by the pultrusion processes. The effects of the processing parameters on the mechanical properties (flexural strength and flexural modulus, etc.) of the glass fiber reinforced UF composites by pultrusion has been studied. The processing variables investigated included die temperature, pulling speed, postcure temperature and time, filler type and content, and glass fiber content. The die temperature was determined from differential scanning calorimetry (DSC) diagram, swelling ratio, and mechanical properties tests. It was found that the mechanical properties increased with increasing die temperature and glass fiber content, and with decreasing pulling rate. The die temperature, pulling speed, and glass fiber content were determined to be 220°C, 20–80 cm/min, and 60–75 vol%, respectively. The mechanical properties reached a maximum value at 10, 5, 5, and 3 phr filler content corresponding to the kaolin, talc, mica, and calcium carbonate, respectively, and then decreased. The mechanical properties increase at a suitable postcure temperature and time. Furthermore, the properties that decreased due to the degradation of composite materials for a long postcure time are discussed. POLYM. COMPOS., 27:8–14, 2006. © 2005 Society of Plastics Engineers
Studies on nylon‐6/EVOH/clay ternary composites
Authors: Artzi N. , Khatua B. B. , Narkis M. , Siegmann A.
Published: December 2005

Nylon‐6 (Ny‐6)/EVOH blends are interesting host multiphase systems for incorporation of low clay contents. The Ny‐6/EVOH blend is a unique system, which tends to chemically react during melt‐mixing, affecting thermal, morphological and mechanical properties of the ternary systems containing clay. The addition of clay seems to interrupt the chemical reaction between the host polymers at certain compositions, leading to lower blending torque levels when clay is added. A competition between Ny‐6 and EVOH regarding the intercalation process takes place. Ny‐6 seems to lead to exfoliated structure, whereas EVOH forms intercalated structure, as revealed from XRD and TEM analyses, owing to thermodynamic considerations and preferential localization of the clay in Ny‐6. Hence, the ternary systems have combined intercalated and delaminated morphology or complete exfoliated morphology depending on blend composition and clay content. Selective extraction experiments (gel content) indicate the formation of chemical reaction between the Ny‐6 and EVOH, and give an indirect indication of the polymer content residing in the galleries. The thermal properties of the polymers were found to be affected by the occurrence of chemical reaction, the level of intercalation and exfoliation and plasticizing effect of the low molecular weight onium ions treating the clay. Of special interest is the increased storage modulus attained upon the addition of only 1.5 wt% clay. POLYM. COMPOS. 27:15–23, 2006. © 2005 Society of Plastics Engineers
Measuring and predicting in‐plane thermal conductivity of carbon‐filled nylon 6,6 polymer composites
Authors: Keith Jason M. , Hingst Carl D. , Miller Michael G. , King Julia A. , Hauser Rebecca A.
Published: December 2005

In this study, two different carbons (synthetic graphite particles and carbon fiber) were added to nylon 6,6, and the resulting composites were tested for both the through‐plane thermal conductivity kthru and the in‐plane thermal conductivity kin, using the transient plane source method. The first goal of this work was to use a finite element model to develop a procedure to accurately measure the material properties using this relatively new analytical procedure. Reproducible data can be obtained for nylon 6,6 polymer composites, by choosing a power dissipation (an input parameter to the transient plane source method) corresponding to a sensor temperature increase of 2 K above the initial temperature after 5 s. The second goal of this work was to develop a simple empirical model for the in‐plane thermal conductivity, which is easily measured with the transient plane source method. The results show that the product of the through‐plane and in‐plane thermal conductivities is a linear function of the volume percent ϕ. As the through‐plane thermal conductivity of these composites is accurately predicted with a modified Nielsen model, this empirical relationship can be used to estimate in‐plane thermal conductivities for a range of applications. POLYM. COMPOS. 27:1–7, 2006. © 2005 Society of Plastics Engineers
Differential protein expression in the metal‐reducing bacterium Geobacter sulfurreducens strain PCA grown with fumarate or ferric citrate
Authors: Khare Tripti , Esteve‐Núñez Abraham , Nevin Kelly P. , Zhu Wenhong , Yates John R. , Lovley Derek , Giometti Carol S.
Published: December 2005

Geobacter sulfurreducens, generally considered to be a strict anaerobe, is a predominant microbe in subsurface environments, where it utilizes available metals as electron acceptors. To better understand the metabolic processes involved in the metal‐reduction capability of this microbe, the proteins expressed by cells grown anaerobically with either fumarate or ferric citrate as electron acceptor were compared. Proteins were separated by 2‐DE under denaturing or nondenaturing conditions, and proteins varying in abundance with a high level of statistical significance (p<0.0001) were identified by peptide mass analysis. Denaturing 2‐DE revealed significant differences in the relative abundance of the membrane proteins OmpA and peptidoglycan‐associated lipoprotein, several metabolic enzymes, and, in addition, superoxide dismutase and rubredoxin oxidoreductase. Nondenaturing 2‐DE revealed elevated catalase in cells grown with ferric citrate. These results suggest that, in addition to adjustments in membrane transport and specific metabolic pathways in response to these two different electron acceptors, distinct differences exist in the oxidative environment within the cell when fumarate or soluble ferric citrate is provided as electron acceptor. Although an anaerobe, G. sulfurreducens appears to have alternate mechanisms for dealing with reactive oxygen species in response to increased intracellular soluble iron.
The proteome of mouse mucosal mast cell homologues: The role of transforming growth factor β1
Authors: Pemberton Alan D. , Brown Jeremy K. , Wright Steven H. , Knight Pamela A. , Miller Hugh R. P.
Published: December 2005

Mast cells migrate to the mucosal epithelium during intestinal nematode infections in mice, where they express abundant mucosal mast cell‐specific proteases, mouse mast cell protease‐1 and ‐2 (MCPT1 and MCPT2). Expression of these proteases is strictly controlled by transforming growth factor‐β1 (TGF‐β1) in the epithelium. In vitro homologues of mucosal mast cells are generated by culturing bone marrow‐derived mast cells (BMMC) in the presence of TGF‐β1. We examined the proteome of BMMC cultured either in the presence of TGF‐β1 (n = 5) or of a neutralising anti‐TGF‐β1 antibody (n = 5). Cell extracts were examined by 2‐DE, and changes in expression levels of protein spots were determined by densitometry. Spots of interest were identified by tryptic peptide mapping. In addition to the up‐regulation of MCPT1 and MCPT2, which accounted for approximately 40% of all soluble protein in the TGF‐β1 treated cells, MCPT7 was modestly up‐regulated by TGF‐β1, and calnexin was up‐regulated fivefold. A 7.6‐fold down‐regulation of galectin‐1 was verified by Western blotting and FACS analysis. Galectin‐1 is located on the cell surface where it mediates cellular adhesion to basement membranes. Regulation of its expression by TGF‐β1 may be of relevance to mast cell adhesion within the epithelium.
Microwave‐assisted specific chemical digestion for rapid protein identification
Authors: Hua Lin , Low Teck Yew , Sze Siu Kwan
Published: December 2005

We have developed a rapid microwave‐assisted protein digestion technique based on classic acid hydrolysis reaction with 2% formic acid solution. In this mild chemical environment, proteins are hydrolyzed to peptides, which can be directly analyzed by MALDI‐MS or ESI‐MS without prior sample purification. Dilute formic acid cleaves proteins specifically at the C‐terminal of aspartyl (Asp) residues within 10 min of exposure to microwave irradiation. By adjusting the irradiation time, we found that the extent of protein fragmentation can be controlled, as shown by the single fragmentation of myoglobin at the C‐terminal of any of the Asp residues. The efficacy and simplicity of this technique for protein identification are demonstrated by the peptide mass maps of in‐gel digested myoglobin and BSA, as well as proteins isolated from Escherichia coli K12 cells.
Polyimides from isomeric diphenylthioether dianhydrides
Authors: Zhang Min , Wang Zhen , Gao Lianxun , Ding Menxian
Published: December 2005

3,3′,4,4′‐Diphenylthioether dianhydride (4,4′‐TDPA), 2,3,3′,4′‐diphenylthioether dianhydride (3,4′‐TDPA), and 2,2′,3,3′‐diphenylthioether dianhydride (3,3′‐TDPA) were synthesized from 3‐chlorophthalic anhydride and 4‐chlorophthalic anhydride. A series of polyimides derived from the isomeric diphenylthioether dianhydrides with several diamines were prepared. The properties, such as the solubility, thermal and mechanical behavior, dynamic mechanical behavior, wide‐angle X‐ray diffraction, and permeability to some gases, were compared among the isomeric polyimides. Both 3,3′‐TDPA‐ and 3,4′‐TDPA‐based polyimides had good solubility in polar aprotic solvents and phenols. The 5% weight loss temperatures of all the obtained polyimides was near 500 °C in nitrogen. The glass‐transition temperatures decreased according to the order of the polyimides based on 3,3′‐TDPA, 3,4′‐TDPA, and 4,4′‐TDPA. The 3,4′‐TDPA‐based polyimides had the best permeability and lowest permselectivity, whereas the 4,4′‐TDPA‐based polyimides had the highest permselectivity and the lowest permeability of the three isomers. Furthermore, the rheological properties of thermoplastic polyimide resins based on the isomeric diphenylthioether dianhydrides were investigated, and they showed that polyimide 3,4′‐TDPA/4,4‐oxydianiline had the lowest melt viscosity among the isomers; this indicated that the melt processibility had been greatly improved. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 959–967, 2006
Morphology, interface polarity and branching of electrochemically etched pores in InP
Authors: Spiecker E. , Rudel M. , Jäger W. , Leisner M. , Föll H.
Published: December 2005

The present issue of physica status solidi (a), guest‐edited by Martin Albrecht, has been assembled in honour of Professor Horst P. Strunk, Erlangen, on the occasion of his 65th birthday.

The cover picture illustrates the morphology of pores after electrochemical etching of indium phosphide by bright‐field transmission electron micrographs (TEM) under various crystal projections: The upper figures show pore tips imaged in a 〈110〉 projection with pronounced {111}A facets (left image) and short {001} facets edge‐on (right image). The lower left figure contains a pore tip (top right) ending in the TEM specimen and a pore intersecting the specimen, imaged along the 〈111〉 pore axis. Inclined pores in a [001] plan‐view sample imaged under tilted geometry (∼35° tilt) along a 〈112〉 direction are visible in the lower right figure.
Electric transport and coding sequences of DNA molecules
Authors: Shih C. T.
Published: December 2005

A tight‐binding model is used to investigate the relation between the electric transport properties and the sequences of protein‐coding regions of complete genomes. The sequence‐dependent transmission coefficient for some particular propagation length wG is closely related to the positions of genes on DNA. wG is the “characteristic migration length” for each species. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A DMRG study of a level coupled to a 1D interacting lead
Authors: Weiss Yuval , Sade Miri , Goldstein Moshe , Berkovits Richard
Published: December 2005

The influence of nearest neighbor interactions in a reservoir coupled to a single level dot on the width of the level is studied, using the density matrix renormalization group (DMRG) method. We find that while in the Luttinger liquid (LL) phase of the lead (i.e., for weak interactions) the interactions cause a gradual decrease of the resonance width, in the charge density wave (CDW) phase (for strong interactions) the width is zero, and a sharp jump of the dot population occurs. We explain the physical difference between both cases. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Homocystinuria: Studies on cystathionine β‐synthase,S‐adenosylmethionine synthetase and cystathionase activities in skin fibroblasts
Authors: Bittles A. H. , Carson N. A. J.
Published: December 2005

Cystathionine β‐synthase,S‐adenosylmethionine synthetase and cystathionase activities were assayed in skin fibroblast cultures from five pyridoxine responsive and five pyridoxine non‐responsive homocystinurics, six obligate heterozygotes for homocystinuria and ten normal control subjects. The specific deficiency in cystathionine β‐synthase activity was confirmed in nine of the homocystinuric cultures. However, in one pyridoxine responsive case the level of cystathionine β‐synthase activity was found to be comparable with those of the heterozygotes. A negative correlation appeared to exist between the level of residual enzyme activity and the pre‐treatment severity of clinical symptoms.
Two‐dimensional polyacrylamide gel analysis of fibroblast polypeptides: Discussion of its Relevance for inherited diseases
Authors: Choo K. H. , Cotton R. G. H. , Danks D. M. , Norris U.
Published: December 2005

Two‐dimensional polyacrylamide gel electrophoresis has been used to resolve several hundred polypeptides from six different human fibroblast cell lines. Two of the cell lines were from normals while the other four were from patients with diseases of the type known to be due to single gene mutations. Less than 2% of the polypeptides from the different cell lines were found to differ in their electrophoretic mobility. The existence of only a small degree of polypeptide variability in pairwise comparison between cell lines suggests the possibility of employing two‐dimensional gel electrophoretic comparison as a direct approach for the recognition of pathogenetically important polypeptide alterations in genetic diseases.
Antenatal diagnosis of propionic acidaemia by methylcitrate determination
Authors: Dhondt J. L. , Farriaux J. P. , Amedee Manesme O. , Cartigny B. , Sweetman L. , Duran M.
Published: December 2005

Antenatal diagnosis of a case of propionic acidaemia was rapidly achieved by measuring the methylcitrate concentration in amniotic fluid.
Phenylalanine loading tests in genetic counselling: 5 Years experience with its premarital use
Authors: Hyánek J. , Viletová H. , Kunová V. , Kubík M.
Published: December 2005

Genetic counselling has been given to 71 engaged couples at risk of producing a phenylketonuric child. Five marriages were not recommended. None of the 51 children born to the recommended marriages has phenylketonuria.
Two forms of biotin‐responsive multiple carboxylase deficiency
Authors: Sweetman L.
Published: December 2005

Biotin‐responsive multiple carboxylase deficiencies are classified into early and late forms. The early form showed higher urinary excretion of 3‐hydroxyisovalerate and 3‐hydroxypropionate than the late form and was associated with normal plasma biotin concentrations. It is proposed that holocarboxylase synthetase and intestinal biotin absorption are defective in the early and late forms respectively.
Urocanic acid contents in histidinaemic infant and developing rat epidermis
Authors: Ito F. , Ota H. , Aoki K. , Eto Y.
Published: December 2005

The ratio of urocanic acid to histidine in stratum corneum can be used to differentiate patients with histidinaemia from normal subjects. The histidinaemia heterozygotes have intermediate ratios.
Lactic acidosis due to pyruvate carboxylase deficiency
Authors: Haworth J. C. , Robinson B. H. , Perry T. L.
Published: December 2005

Two unrelated Canadian Indian infants presented with metabolic acidosis. Lactate, pyruvate, glutamic acid, proline and alanine were greatly elevated in plasma. Urinary excretion of α‐ketoglutarate and pyruvate was increased. Pyruvate carboxylase activity was very low in skin fibroblasts and liver. Phosphoenolpyruvate carboxykinase was low in liver. Both infants were unresponsive to several enzyme cofactors, including biotin. Both survive at age 2 years with severe mental retardation.
Urinary organic acids in normal full‐term newborns aged 1–7 days
Authors: Tracey B. M. , Doré C. J. , Lawson A. M. , Watts R. W. E. , Chalmers R. A.
Published: December 2005

Urinary organic acid metabolite excretion patterns in normal newborns aged 1 to 7 days were analysed by GC and MS. Statistical analysis showed significantly different relationships between metabolite excretion, age, sex and feed. The data provide a necessary background for the diagnosis of inborn errors of organic acid metabolism.
Intracellular concentrations of phenylalanine, tyrosine and α‐aminobutyric acid in 13 homozygotes and 19 heterozygotes for phenylketonuria compared with 26 normals
Authors: Thalhammer O. , Pollak A. , Lubec G. , Königshofer H.
Published: December 2005

Lymphocytes isolated from homozygotes and heterozygotes for phenylketonuria show increased phenylalanine, tyrosine and α‐aminobutyric acid contents when compared with lymphocytes from normal subjects.
Prolidase deficiency with iminodipeptiduria: Biochemical investigations and first results of attempted therapy
Authors: Charpentier C. , Dagbovie K. , Lemonnier A. , Larregue M. , Johnstone R. A. W.
Published: December 2005

A 33‐year‐old female patient with chronic recurrent leg ulcerations was shown to present a massive iminodipeptiduria which seemed to be attributable to disturbance of collagen metabolism. Biochemical investigations confirmed an hereditary prolidase deficiency. A treatment was tried for the first time and showed a good biochemical result and a clinical improvement.
Screening of high risk infants for metabolic disease in a metropolitan hospital
Authors: Krieger I. E. , Nigro M. , Sarnaik A. , Taqi Q.
Published: December 2005

Screening of symptomatic infants for metabolic diseases is described which led to an improved detection rate because of better awareness and case selection, as well as the use of a test for urinary organic acids.
Pyroglutamic aciduria (5‐Oxoprolinuria) without glutathione synthetase deficiency and with decreased pyroglutamate hydrolase activity
Authors: August Roesel R. , Hommes F. A. , Samper L.
Published: December 2005

A woman with 5‐oxoprolinuria, probably due to a deficiency of pyroglutamate hydrolase, is described. This patients has produced three babies with severe congenital heart disease, the surviving one having a marked hyperprolinaemia.
Analysis of inborn errors of metabolism and other genetic defects in human fibroblasts using two‐dimensional polypeptide mapping
Authors: Singh S. , Willers I. , Goedde H. W. , Klose J.
Published: December 2005

A standardized technique for the two‐dimensional polypeptide mapping of cultured human fibroblasts has been used for the study of cellular protein variations in healthy controls, patients with inborn errors of metabolism and some other genetic defects. The analysis of about 50 gels has established that this method is very reproducible and enables the examination of about 600 polypeptides in a single gel. The inter‐individual variation has been rather low (about 3%). In the gels from patients with genetic defects only very minor qualitative variations have been observed.
Disturbances of amino acid transport in rats with experimental hyperphenylalaninaemia
Authors: Žanić‐Grubišić T. , Lipovac K.
Published: December 2005

Liver and brain cortex slices from rats made hyperphenylalaninaemic withp‐chlorophenylalanine showed decreased leucine uptake but increased uptake of tryptophan and glycine.
Methylmalonic aciduria in a black female child with congenital short femur on the right side
Authors: Meiring J. L. , Strydom A. J. C.
Published: December 2005

The diagnosis of methylmalonic aciduria without recourse to sophisticated laboratory methods can present difficulties due to non‐specific interference with the diazotizedp‐nitroaniline method. This is illustrated by the present case, a black child with a B12‐responsive form of the disease.
Metabolite profiling of human muscle extracts by isotachophoresis
Authors: Oerlemans F. , van Bennekom C. , De Bruyn C. , Kulakowski S.
Published: December 2005

Isotachophoresis provides an effective method of examining purines and pyrimidines in muscle extracts. Its application to dystrophic muscle of the Duchenne type is illustrated.
Fabry's disease: Detection of heterozygotes using blastoid lymphocytes stimulated by phytohaemagglutinin
Authors: Sakuraba H. , Ohga K. , Suzuki Y.
Published: December 2005

Fabry's disease heterozygotes may be detected by measuring α‐galactosidase activity in phytohaemagglutinin‐stimulated lymphocytes.
A new enzymatic method for pyridoxal‐5‐phosphate determination
Authors: Shin‐Buehring Y. S. , Rasshofer R. , Endres W.
Published: December 2005

An improved method for the determination of pyridoxal‐5‐phosphate using tyrosine decarboxylase is described.
Synthesis of conjugates for production of an antibody toortho‐hydroxyphenylacetic acid
Authors: Tyfield L. A. , Ismail A. A. A. , Holton J. B. , McOmie J. F. W.
Published: December 2005

Raising antibodies to a small, chemically simple molecule is difficult. Attempts have been made to develop a simple, sensitive and specific radioimmunoassay for the phenolic compound,o‐hydroxyphenylacetic acid (OHPAA) (mol. wt. 152). To date, five different immunogens have been synthesized. Two conjugates of OHPAA were linked to bovine serum albumin (BSA) and injected into rabbits and three were linked to poly‐l‐lysine for injection into Strain 2 PLL+guinea‐pigs. The peptide linkage in one was via the carboxyl group to the ε‐amino lysine residues of BSA. The other four were linked in a diazo linkage to the carrier polypeptide through an amino group which had been added to the hapten molecule. So far, antibodies specific to the hapten portion of any of the conjugates have not been obtained. Further conjugates containing methoxyphenylacetic acid and a succinate bridge are being prepared.
Neonatal lactic acidosis with pyruvate carboxylase inactivity
Authors: Vidailhet M. , Lefebvre E. , Beley G. , Marsac C.
Published: December 2005

Biochemical findings in a case of acute onset lactic acidosis due to pyruvate carboxylase deficiency are presented. Oxaloacetate deficiency arising from the inactivity of pyruvate carboxylase produces abnormal cytosolic and mitochondrial redox states. The resultant altered metabolite pattern may allow a provisional diagnosis before enzymatic studies.
Metabolic abnormalities in a patient with muscular carnitine deficiency
Authors: Adam O. , Keller C. , Barth C. , Wolfram G.
Published: December 2005

A patient with muscular carnitine deficiency showed little clinical improvement with carnitine supplementation but responded well to the addition of medium‐chain triglycerides to the diet.
Biochemical study of four cases of propionic acidaemia: GC/MS study of urinary metabolites
Authors: Divry P. , Boulieu R. , Cotte J. , Desage M. , Guilluy R.
Published: December 2005

Gas chromatography‐mass spectrometry was used to identify secondary metabolites present in the urine of four cases of propionic acidaemia.