bluuebunny/crossref_metadata_2025 huggingface dataset:
Rates of myocardial infarction and coronary artery disease and risk factors in patients treated with radiation therapy for early‐stage breast cancer
Authors: Jagsi Reshma , Griffith Kent A. , Koelling Todd , Roberts Rachel , Pierce Lori J.
Published: January 2007

BACKGROUND.

Radiation therapy (RT), a critical component of breast‐conserving therapy for breast cancer, has been associated with coronary artery disease (CAD) in numerous older studies, but the risk may be lower with modern techniques.

METHODS.

Observed rates of cardiac events in 828 patients treated with breast‐conserving surgery and RT at the University of Michigan were compared with expected rates. Relations between potential risk factors and actuarial rates of first CAD event were analyzed.

RESULTS.

Observed risks of cardiac events were lower than expected. The standardized incidence ratio (SIR) of myocardial infarction (MI) was 0.44 (95% confidence interval [CI]: 0.21–0.70). The SIR of MI or CAD requiring intervention was 0.50 (95% CI: 0.27–0.68). With a median follow‐up of 6.8 years, 12 (1.4%) patients had at least 1 MI on follow‐up and 20 (2.4%) had at least 1 MI or CAD requiring intervention. Median age at first cardiac event was 75.9 years (range, 43.1–91.5). Median interval from RT to occurrence of the first cardiac event was 3.7 years (range, 13 days to 15.4 years). The 10‐year cumulative incidence of MI was 1.2% and cumulative incidence of MI or CAD requiring intervention was 2.7%. On multivariate analysis, age, diabetes mellitus, active smoking, and laterality of RT were significant predictors of MI. Age and active smoking were significant predictors of MI or CAD requiring intervention.

CONCLUSIONS.

Patients in this series had lower risk of ischemic cardiac events than expected. Although small in absolute magnitude, patients radiated to the left side did have a statistically significant increased risk of MI. These findings support further investigation of techniques to minimize the long‐term cardiac risks faced by breast cancer patients. Cancer 2007 © 2007 American Cancer Society.
TNF‐dependent overexpression of CCL21 is an underlying cause of progressive lymphoaccumulation in generalized lymphoproliferative disorder
Authors: Wiede Florian , Vana Karen , Sedger Lisa M. , Lechner Anja , Körner Heinrich
Published: January 2007

The human condition autoimmune lymphoproliferative syndrome and the murine mutation generalized lymphoproliferative disorder (gld/gld) are both caused by mutations of Fas or Fas ligand and are characterized by severe splenomegaly and lymphadenopathy. In the mouse, the additional absence of TNF attenuates the gld/gld syndrome through an unknown mechanism. We hypothesized that this unexpected outcome was not mediated by increased apoptosis but changes of T cell localization. We demonstrated that the homeostatic chemokine CCL21 is strongly up‐regulated in the spleen of C57BL/6 (B6).gld/gld and B6.gld/gld.TRAIL–/– mice. In contrast, a distinct consequence of TNF deficiency in B6.gld/gld mice was the substantially reduced splenic production of CCL21. An analysis of the cognate chemokine receptor CCR7 showed a complete, age‐dependent down‐regulation of this receptor on B6.gld/gld conventional peripheral T cells that are therefore unable to react to this chemokine. These results demonstrate a new role for the pro‐inflammatory cytokine TNF and the TNF‐regulated chemokine CCL21 in the complex etiology of the autoimmune syndrome in B6.gld/gld mice.
Mimotopes selected with antibodies from HIV‐1‐neutralizing long‐term non‐progressor plasma
Authors: Humbert Michael , Antoni Sascha , Brill Boris , Landersz Margot , Rodes Berta , Soriano Vicente , Wintergerst Uwe , Knechten Heribert , Staszewski Schlomo , von Laer Dorothee , Dittmar Matthias T. , Dietrich Ursula
Published: January 2007

A promising approach to identify HIV‐1 vaccine candidates is to dissect the natural immune response against the virus in persons controlling the infection over decades without any antiviral therapy. Here we focus on a group of such persons, eight long‐term non‐progressors (LTNP), in which we proved the presence of broadly neutralizing antibodies against HIV‐1 in the plasma as very likely cause for their LTNP status. The aim of this study was to identify the epitopes for these neutralizing antibodies, as these should represent immunogens potentially able to elicit neutralizing antibodies upon vaccination. We screened random peptide phage libraries with plasma antibodies from eight LTNP. After several rounds of positive and negative selection, about 700 HIV‐specific mimotopes were sequenced. The mimotope sequences were analyzed for homology to HIV‐1 Env, in particular for their capacity to represent conformational epitopes on the surface of the gp120 structure using our software 3DEX. Related phage groups were analyzed for crossreactivity with the LTNP plasma by ELISA as well as for their capacity to induce HIV‐1‐neutralizing antibodies in mice. Based on this study interesting mimotopes can now be selected for further immunization studies.
Plastic fats and margarines through fractionation, blending and interesterification of milk fat
Authors: De Bijay Krishna , Hakimji Muzammil , Patel Avnish , Sharma Deepan , Desai Himanshu , Kumar Trivendra
Published: January 2007

Milk fat stearins and oleins were blended with high‐ and low‐melting natural fats to produce plastic fats, vanaspati substitute and confectionery fats. Margarines of improved nutritional value were also formulated. Fractionation was carried out using acetone, hexane, and isopropyl alcohol. The yield (wt‐%) of high‐melting stearin (HMS) from acetone and IPA was 13.0 ± 0.2 to 13.3 ± 0.1 after crystallization for 24 h at 20 °C. The melting point of the products was 49.0 ± 0.5 to 49.8 ± 0.6 °C. However, in hexane the yield of HMS was 12.2 ± 0.2% at 10 °C. The olein fractions were further fractionated at 10 °C from acetone and IPA, and at 0 °C from hexane, to obtain superoleins and low‐melting stearins (LMS). HMS fractions were blended with rice bran oil and cottonseed oil at the ratio 70 : 30 (wt/wt), and the superoleins were blended with sal fat and palm stearin at the ratios 40 : 60, 30 : 70 and 20 : 80 (wt/wt). The blends were interesterified (product melting point: 22.7 ± 0.04 to 39.3 ± 0.10 °C) chemically and enzymatically to prepare margarine. The penetration values (in 0.1 mm) of these margarines were noted to be 112 ± 1.52 to 145 ± 0.00.
Inhibition of lipid peroxidation by anthocyanins, anthocyanidins and their phenolic degradation products
Authors: Brown Jonathan E. , Kelly Mary F.
Published: January 2007

Food components that delay or prevent biomolecule oxidation may be relevant in shelf life extension as well as disease prevention. Anthocyanins are a potentially important group of compounds, but they are prone to degradation both in vitro and in vivo, producing simple phenols. In this study, eight structurally related (poly)phenols [anthocyan(id)ins and phenolic acids] were examined for their ability to inhibit lipid oxidation at physiologically relevant concentrations (100–1000 nM) using the Cu2+‐mediated low‐density lipoprotein oxidation model. Interaction between each (poly)phenol and Cu2+ ions was also investigated. (Poly)phenols with an ortho‐dihydroxy group arrangement, i.e. cyanidin‐3‐glucoside, cyanidin and protocatechuic acid, were the most effective within their class, extending the lag phase to oxidation by 137, 255 and 402%, respectively (at 1000 nM). At the same concentration, trihydroxy‐substituted compounds (delphinidin and gallic acid) were of intermediate efficacy, extending the lag phase by 175 and 38%, respectively. Compounds with the 4'‐hydroxy‐3',5'‐methoxy arrangement (i.e. malvidin‐3‐glucoside and malvidin) were the least effective (3 and 58% extension, respectively), while syringic acid (4‐hydroxy‐3,5‐dihydroxy benzoic acid) was pro‐oxidant (lag phase shortened by 31%). (Poly)phenols with the ortho‐dihydroxy arrangement chelated Cu2+ ions, which in part explains their greater efficacy over the other (poly)phenols in this model oxidation system. However, differences in their hydrogen‐donating properties and their partitioning between lipid and hydrophilic phases are also relevant in explaining these structure‐activity relationships.
Risk assessment for prion protein reduction under the conditions of the biodiesel production process
Authors: Mittelbach Martin , Pokits Bernd , Müller Henrik , Müller Mario , Riesner Detlev
Published: January 2007

Due to the increased demand for biofuels, all different feedstocks from oils and fats have to be considered for biodiesel production. Animal fats have proved to be excellent sources for biodiesel due to their high cetane number and good stability. Large amounts of fat from so‐called high‐risk material, possibly contaminated with infectious prions, are available for biodiesel production. In this paper, the grade of destruction of prions during the biodiesel production process, including pre‐esterification with conc. sulfuric acid followed by KOH‐catalyzed transesterification, was studied. The starting material of the different production steps was spiked with purified and highly infectious prion rods, and the destruction of these prions was determined by gel electrophoresis (SDS‐PAGE) and Western blot. The pre‐esterification step led to a destruction factor of at least 100, the transesterification led to a factor of at least 250, and the distillation of the final biodiesel showed a destruction factor of at least 1000. During all experiments, no traces of prions could be detected after the different reaction steps. Based on these data, a complete and unequivocal risk assessment regarding the industrial process of biodiesel production was carried out, leading to a calculated overall risk of 5.8×10−15 ID50 units/person and year, which means that a hypothetical BSE contamination from biodiesel is more than 109 times lower than the background risk.
Carotenoid pattern in Blakeslea trispora grown on oil‐enriched substrates with regard to triacylglycerol species accumulation
Authors: Mantzouridou Fani , Tsimidou Maria Z.
Published: January 2007

The carotenoid pattern in Blakeslea trispora grown on oil‐enriched substrates was investigated with regard to triacylglycerol (TAG) species accumulation, to assess the interrelationship between these two processes. Analysis of individual carotenoids and TAG was carried out by HPLC. β‐Carotene production was at the expense of lycopene and γ‐carotene formation in cells grown on crude olive pomace oil (COPO) and crude soybean oil (CSO) at two levels of addition (10.0 and 30.0 g/L culture medium). A shift to γ‐carotene synthesis was observed at increased oil level. Cellular lipids produced at the low COPO or CSO levels contained more unsaturated TAG compared with those obtained on glucose as the sole carbon source. With regard to the typical soybean or olive oil TAG profile, cellular TAG had profiles dependent on the type and the amount of the co‐substrates used. In the presence of CSO, the cellular TAG profile was similar to that of the respective oil for both levels of addition. A notable desaturase activity was observed only in the presence of low COPO addition. The present study can serve as a basis for a better understanding of TAG accumulation with regard to β‐carotene production in oil‐enriched substrates.
Stereospecific distribution of fatty acids in triacylglycerols of olive oils
Authors: Vichi Stefania , Pizzale Lorena , Conte Lanfranco S.
Published: January 2007

The positional distribution of fatty acids (FA) in triacylglycerols (TAG) of 47 virgin olive oils from diverse cultivars grown in distinct areas of North‐Eastern Italy was studied. Few data were previously available on oils from these geographical areas. The effects of climatic and geographical conditions on the stereospecific distribution of TAG in olive oil were confirmed. Moreover, the results of the stereospecific analysis were used to evaluate the preferential esterification position of each FA on the basis of the degree of unsaturation and the chain length. The data of the stereospecific analysis of olive oil TAG can contribute to the determination of the selectivity of olive fruit acyltransferases for distinct FA.
Fatty acid profile changes during orange juice‐milk beverage processing by high‐pulsed electric field
Authors: Zulueta Ana , Esteve María J. , Frasquet Isabel , Frígola Ana
Published: January 2007

High‐intensity pulsed electric fields (HIPEF) is an emerging non‐thermal food preservation technology which has the potential to pasteurize pumpable liquid foods. Its application is being studied to evaluate it as potential alternative or complementary process to thermal pasteurization. Orange juice‐milk beverage with added bioactive components is a ready‐to‐drink beverage developed as an alternative to traditional soft drinks. In the present work, two HIPEF treatments (35 and 40 kV/cm) and six different treatment times (from 40 to 180 µs) were evaluated to assess their effect on the fatty acid profile of an orange juice‐milk beverage fortified with n‐3 fatty acids and oleic acid. The effect of HIPEF treatment on various physicochemical properties of the beverages: pH, °Brix, hydroxymethylfurfural or peroxide index was also determined. After HIPEF treatment, non‐significant changes in the contents of saturated fatty acids, monounsaturated fatty acids or polyunsaturated fatty acids were observed. Neither peroxides nor intolerable levels of furfurals were detected. Only a small reduction in fat content (p <0.05) was found. In conclusion, HIPEF can be proposed as an alternative preservation technology due to these minimal changes which are negligible from the nutritional point of view.
Synthesis of Novel Di‐ and Trisaccharide Mimetics with Non‐Glycosidic Amino Bridges
Authors: Neumann Janna , Weingarten Saskia , Thiem Joachim
Published: January 2007

Synthesis of novel di‐ and trisaccharides using enzymatic glycosylation, Dess–Martin oxidation and reductive amination allows rapid access to the target structures. Thus, a novel class of glycomimetics was obtained having nitrogen inserted as bridging atom between two non‐anomeric positions. Novel di‐ and trisaccharide mimetics were designed using N‐acetylglucosamine as a basis structure. A third monosaccharide unit was attached via an unnatural sugar–sugar bond without participation of the anomeric center. Their synthesis, proceeding via oxidation, glycosylation and reductive amination, required only a few steps, thus allowing rapid access to the target structures. Generation of the novel pseudo‐disaccharide was achieved by Dess–Martin oxidation and a subsequent reductive amination. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
A new outer boundary formulation and energy corrections for the nonlinear Poisson–Boltzmann equation
Authors: Boschitsch Alexander H. , Fenley Marcia O.
Published: January 2007

The nonlinear Poisson–Boltzmann equation (PBE) has been successfully used for the prediction of numerous electrostatic properties of highly charged biopolyelectrolytes immersed in aqueous salt solutions. While numerous numerical solvers for the 3D PBE have been developed, the formulation of the outer boundary treatments used in these methods has only been loosely addressed, especially in the nonlinear case. The de facto standard in current nonlinear PBE implementations is to either set the potential at the outer boundaries to zero or estimate it using the (linear) Debye–Hückel (DH) approximation. However, an assessment of how these outer boundary treatments affect the overall solution accuracy does not appear to have been previously made. As will be demonstrated here, both approximations can, under certain conditions, produce completely erroneous estimates of the potential and energy salt dependencies. A related concern for calculations carried out on grids of finite extent (e.g., all current finite difference and finite element implementations) is the contribution to the energy and salt dependence from the exterior region outside the computational grid. This too is shown to be significant, especially at low salt concentration where essentially all of the contributions to the excess osmotic pressure and ion stress energies originate from this exterior region. In this paper the authors introduce a new outer boundary treatment that is valid for both the linear and nonlinear PBE. The authors also formulate energy corrections to account for contributions from outside the computational domain. Finally, the authors also consider the effects of general ion exclusion layers upon biomolecular electrostatics. It is shown that while these layers tend to increase the surface electrostatic potential, under physiological salt conditions and high net charges their effect on the excess osmotic pressure term, which is a measure of the salt dependence of the total electrostatic free energy, is weak. To facilitate presentation and allow very fine resolutions and/or large computational domains to be considered, attention is restricted to the 1D spherically symmetric nonlinear PBE. Though geometrically limited, the modeling principles nevertheless extend to general PBE solvers as discussed in the Appendix. The 1D model can also be used to benchmark and validate the salt effect prediction capabilities of existing PBE solvers. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
A generalized direct‐particle‐deletion scheme for the calculation of chemical potential and solubilities of small‐ and medium‐sized molecules in amorphous polymers
Authors: Siegert Martin R. , Heuchel Matthias , Hofmann Dieter
Published: January 2007

The development, validation, and first applications of a generalized version of an inverse Widom method are described. It permits the calculation of solubility coefficients for molecules as large as, e.g., benzene in all polymers for which reasonable forcefield parameters exist. Predicting the solubility is a key to the knowledge‐based design of materials utilized to solve permeability related problems. For long time, particle insertion methods, such as the Widom method, were the only way to predict solubilities from molecular models, but they, in most cases, only worked well for rather small penetrants (e.g., H2, O2, N2). Therefore, a few years ago, a new particle deletion algorithm “DPD” was introduced by Boulougouris, Economou, and Theodorou to overcome this problem in principle. The related computer code was, however, only applicable to special, relatively simple model systems. As application examples for the generalized version described here, solubility calculations for nitrogen, oxygen, and benzene in poly(dimethyl siloxane) are presented. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
An ant algorithm for the conformational analysis of flexible molecules
Authors: Daeyaert Frits , De Jonge Marc , Koymans Luc , Vinkers Maarten
Published: January 2007

Originally, the ant system was developed for optimization in discrete search spaces such as the traveling salesman problem. We detail our adaptation of the algorithm to optimization in the continuous search space of conformational analysis. The parameters of the algorithm were tuned using a simple test molecule, undecane, and a drug molecule, imatinib. The algorithm is further tested on four more drug or drug‐like molecules, on vitamin A and on alanine tetrapeptide. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Theoretical study on the methyl radical with chlorinated methyl radicals CH3−nCln (n = 1, 2, 3) and CCl2
Authors: Wang Jian , Ding Yi‐Hong , Zhang Shao‐Wen , Sun Chia‐Chung
Published: January 2007

Radical–radical reactions involving chlorinated methyl radicals are particularly important in the mechanism of combustion of chlorinated hydrocarbons. Yet, they are usually difficult to study experimentally. In this paper, four chloride‐related radical–radical reactions, i.e., CH3+CH3−nCln (n = 1, 2, 3) and CH3+CCl2, are theoretically studied for the first time by means of the Gaussian‐3//B3LYP potential energy surface survey combined with the master equation study over a wide range of temperatures and pressures. Our calculated results show that the three CH3+CH3−nCln reactions can barrierlessly generate the former two kinetically allowed products P1 H2CC(H)3−nCln−1+HCl and P2 CH3CH3−nCln−1+Cl with the very high predominance of P1 over P2. For the CH3 reaction with the biradical CCl2, which inevitably takes place during the CH3+CCl3 reaction and yet has never been studied experimentally or theoretically, H2CCCl2+H and H2CC(H)Cl+Cl are predicted to be the respective major and minor products. The results are compared with the recent laser photolysis/photoionization mass spectroscopy study on the CH3+CH3−nCln (n = 1, 2, 3) reactions. The predicted rate constants and product branching ratios of the CH3+CCl2 reaction await future experimental verification. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
A produce‐to‐stock system with advance demand information and secondary customers
Authors: Iravani Seyed M.R. , Liu Tieming , Luangkesorn K.L. , Simchi‐Levi David
Published: January 2007

We consider a manufacturer (i.e., a capacitated supplier) that produces to stock and has two classes of customers. The primary customer places orders at regular intervals of time for a random quantity, while the secondary customers request a single item at random times. At a predetermined time the manufacturer receives advance demand information regarding the order size of the primary customer. If the manufacturer is not able to fill the primary customer's demand, there is a penalty. On the other hand, serving the secondary customers results in additional profit; however, the manufacturer can refuse to serve the secondary customers in order to reserve inventory for the primary customer. We characterize the manufacturer's optimal production and stock reservation policies that maximize the manufacturer's discounted profit and the average profit per unit time. We show that these policies are threshold‐type policies, and these thresholds are monotone with respect to the primary customer's order size. Using a numerical study we provide insights into how the value of information is affected by the relative demand size of the primary and secondary customers. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007
Analysis of decentralized multi‐product pull systems with lost sales
Authors: Gurgur Cigdem Z. , Altiok Tayfur
Published: January 2007

We study a pull‐type, flexible, multi‐product, and multi‐stage production/inventory system with decentralized two‐card kanban control policies. Each stage involves a processor and two buffers with finite target levels. Production stages, arranged in series, can process several product types one at a time. Transportation of semi‐finished parts from one stage to another is performed in fixed lot sizes. The exact analysis is mathematically intractable even for smaller systems. We present a robust approximation algorithm to model two‐card kanban systems with batch transfers under arbitrary complexity. The algorithm uses phase‐type modeling to find effective processing times and busy period analysis to identify delays among product types in resource contention. Our algorithm reduces the effort required for estimating performance measures by a considerable margin and resolves the state–space explosion problem of analytical approaches.

Using this analytical tool, we present new findings for a better understanding of some tactical and operational issues. We show that flow of material in small procurement sizes smoothes flow of information within the system, but also necessitates more frequent shipments between stages, raising the risk of late delivery. Balancing the risk of information delays vis‐à‐vis shipment delays is critical for the success of two‐card kanban systems. Although product variety causes time wasted in setup operations, it also facilitates relatively short production cycles enabling processors to switch from one product type to another more rapidly. The latter point is crucial especially in high‐demand environments. Increasing production line size prevents quick response to customer demand, but it may improve system performance if the vendor lead‐time is long or subject to high variation. Finally, variability in transportation and processing times causes the most damage if it arises at stages closer to the customer. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007
The Eastern European referendum campaigns on the accession to the European Union–a critical analysis
Authors: Szondi György
Published: January 2007

This article analyses the communication campaigns organized to increase support for European Union (EU) membership, during referendums held between March and September 2003 in Central Europe. The focus is on the official campaigns, organized and sponsored by the Hungarian, Polish and Estonian governments. The first part of the paper reviews the special characteristics of referendums and information campaigns, followed by the challenges communication planners faced, during planning and implementing the campaigns. The common features and themes of the national campaigns, as well as the differences, are identified and analysed. The article concludes with some important lessons and recommendations to be used by future referendum campaign planners and implementers.

Copyright © 2007 John Wiley & Sons, Ltd.
How to become your own worst adversary: examining the connection between managerial attributions and organizational relationships with public interest stakeholders
Authors: Mattingly James E.
Published: January 2007

According to numerous studies across multiple disciplines in the social sciences, business organizations tend to develop adversarial relationships with representatives of the public interest. A survey of 62 Public Affairs Managers in publicly held U.S. corporations finds that organizations adopt relational styles similar to those theorized in studies of inter‐organizational conflict, organizational communication and stakeholder management. Empirical results support the descriptive power of a two‐dimensional model reflecting four relational styles that participating organizations exhibited: avoidance, compliance, co‐optation and negotiation. The two dimensions that constitute the model are cooperativeness and boundary spanning. More importantly, managers who attributed power and legitimacy to public interest group stakeholders reported that their organizations were more likely to cooperate with these stakeholders. On the other hand, managers who perceived public interest groups' claims having urgency were more likely to develop communicative, boundary spanning relationships with public interest groups but these relationships were less likely to be cooperative. Because unhealthy relationships with these groups can be detrimental to an organization's long‐term prospects, managers must be careful to recognize public interest organizations as potent and legitimate potential allies.

Copyright © 2007 John Wiley & Sons, Ltd.
Ausrichtung von Partikeln in stationären Strömungsfeldern
Authors: Altenbach H. , Naumenko K. , Pylypenko S. , Renner B.
Published: January 2007

Zahlreiche komplexe Kunststoffbauteile für industrielle Anwendungen werden im Spritzgussprozess hergestellt. Um mechanische Eigenschaften zu verbessern, verstärkt man u. a. die Kunststoffe mit Kurzglasfasern. Die Eigenschaften hängen dabei von der Faserorientierung ab. In dieser Arbeit wird die Ausrichtung eines einzelnen Partikels in einem Strömungsfeld behandelt. Ausgehend von der Drehimpulsbilanz wird die Bewegungsgleichung für die Drehung des Partikels hergeleitet. Es werden Konstitutivannahmen für die Wechselwirkung mit dem umgebenden Medium gemacht, effiziente numerische Lösungsverfahren werden diskutiert und die erhaltene Lösung wird mit der traditionellen Lösung nach Jeffery [1] verglichen. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling of non‐classical thermoelasticity
Authors: Bargmann Swantje , Steinmann Paul
Published: January 2007

The present contribution deals with computational modeling of non‐classical theories according to the approach of Green and Naghdi [1]. Their theory is subdivided into three types of heat conduction, labeled type I, II and III. Each of the three heat equations is coupled with the balance of momentum. The arising partial di.erential equations are discretized with a Galerkin finite element method in time as well as in space. All three types are applied to an isotropic and homogeneous elastic‐deformable continuum and studied by a numerical example. The reader is also referred to [2, 3] for a more detailed description of the introduced results. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of wave propagation in the fluid‐saturated porous media
Authors: Chen Zhiyun , Steeb Holger , Diebels Stefan
Published: January 2007

In the present work, a so‐called hybrid two‐phase model composed of a materially incompressible solid and a compressible pore fluid is studied. The mechanical behavior is described by the thermodynamically consistent Theory of Porous Media (TPM). Numerical experiments were performed with the space‐time coupled discontinuous galerkin (DGT)‐method. The existence of two compressional waves (P‐waves) and one shear wave (S‐wave) was confirmed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An analytical solution of a 3d problem of magnetoelasticity
Authors: Dashko Olga
Published: January 2007

A behavior of the soft ferromagnetic solid in a magnetic field is conventionally investigated with the framework of the developed by Brown, Pao and Yeh linear theory of magnetoelasticity. Beside of the general two‐dimensional magnetoelastic problems have been successfully studied by Shindo and other researchers, the three‐dimensional problems of magnetoelasticity have not been explored with some exceptions. For example the case of infinite solid with an ellipsoidal inclusion when its shape is essentially compressed in the direction of magnetic field propagation was considered using the series of simplifying assumptions. In the present paper a new approach to finding the solution for the solid with an inclusion of arbitrary ellipsoidal shape was offered. The problem was solved using a general method of constructions the exact analytical solutions of the static problem, which has been developed by Podil'chuk on the basis of Fourier method. This method implies the using of curvilinear coordinates and separating of variables in the governing equations. As a result magnetoelastic stresses was obtained in the closed form. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase transition processes of pore fluids in porous materials
Authors: Graf T. , Ehlers W.
Published: January 2007

Taking a closer look on, e. g., storage processes of greenhouse gases in deep geological aquifers or pressure decreases in dilatant shear bands, the observation can be made that pressure and temperature changes in porous materials can induce phase transition processes of the respective pore fluids. For a numerical simulation of this behaviour, a continuum mechanical model based on a multiphasic formulation embedded in the well‐founded framework of the Theory of Porous Media (TPM) is presented in this contribution. The single phases are an elasto‐viscoplastic solid skeleton, a materially compressible pore gas consisting of the components air and gaseous pore water (water vapour) and a materially incompressible pore liquid, i. e., liquid pore water. The numerical treatment is based on the weak formulations of the governing equations, whereas the primary variables are the temperature of the mixture, the displacement of the solid skeleton and the effective pressures of the pore fluids. An initial boundary‐value problem is discussed in detail, where the resulting system of strongly coupled differential‐algebraic equations is solved by the FE tool PANDAS. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Size Effects due to the Formation of Interphases in Polymer Joints
Authors: Johlitz Michael , Steeb Holger , Diebels Stefan
Published: January 2007

In this contribution we investigate the numerical modelling of polymer bonds under quasi‐static and isothermal conditions. From experimental investigations it is known that polymers form interphases in contact with substrates. These interphases influence the macroscopic material behaviour in the form of size effects, which are observed either in the form “Smaller is Stiffer” or “Smaller is Weaker” depending on the substrate. Taking the formation of the microstructure into account, we postulate an additional balance equation based on an abstract scalar‐valued structure parameter which offers us a way to consider the interphases. We investigate the coupled model consisting of the balance of linear momentum and the balance of the structure parameter by finite element analysis. Different numerical examples are shown. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Beschreibung der Zeitskalenproblematik bei Bremsvorgängen
Authors: Müller M. , Ostermeyer G. P.
Published: January 2007

Das globale Reib‐ und Verschleißverhalten von Bremssystemen ist eng gekoppelt an dasWachstum und die Zerstörung charakteristischer mesoskopischer Strukturen auf der Oberfläche eines Bremsbelages [1]. Diese reibintensiven “Patches” tragen einen Großteil der Reibleistung und stellen durch ihre Härte [2] ein “Schutzschild” für darunter befindliches weicheres Material dar. Aus diesem Grund ist es im Allgemeinen bei Bremssystemen nicht möglich, Reibung und Verschleiß zu separieren. Die aus dem Auf‐ und Abbau der Patches resultierende Wechselwirkung zwischen Reibung und Verschleiß ist mit Hilfe eines dynamischen Reibgesetzes [3] formuliert worden, womit es bereits möglich ist, einfache Phänomene, wie zum Beispiel das Fading oder Hystereseverläufe auf verschiedenen Zeitskalen abzubilden. Um einen detaillierteren Einblick in die Dynamik der Grenzschicht zu erhalten, wurde eine Diskretisierung mit einem Zellulären Automaten eingeführt [4]. Mit Hilfe der definierten Eigenschaften (inneren Variablen) “Temperatur”, “Status”, “Verschleißpartikeldichte” und “Normalleistung” und deren Verknüpfung durch einen implementierten Satz von Regeln konnten die wesentlichen Mechanismen abgebildet [5] und somit die Konsistenz des Regelwerkes nachgewiesen werden. Dabei ist die Problemstellung konfrontiert mit einem breiten Spektrum an Zeitskalen. Eine Konkretisierung des Problems sowie eine Möglichkeit zur Lösung werden in diesem Paper vorgestellt. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase field simulations in ferroelectric materials
Authors: Schrade D. , Müller R. , Gross D.
Published: January 2007

The hindering of domain wall movement by defects in ferroelectric materials is closely connected to electric fatigue. A movable domain wall in a ferroelectric material in most cases is modelled as a singular surface which allows the use of configurational forces. In contrast, the present approach treats the polarization as an order parameter, extending the total energy by a phase separation energy and a domain wall energy. The polarization then no longer has a discontinuity at the domain wall but is a continuous vector field (phase field). As an example, a numerical simulation of domain evolution under stress free boundary conditions is presented. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
FSI of a Simplified Aero Engine Compressor Cascade Configuration
Authors: Schrape Sven , Kühhorn Arnold , Golze Mark
Published: January 2007

A first approach of fully coupled computations of blade vibrations in a two dimensional compressor cascade configuration will be presented in this article. The simulations are realised applying an explicit, partitioned coupling approach between established CFD‐ and FEM‐codes. Investigations are focussed on numerical effects and behaviour on blade vibrations such as damping and frequency shift dependent on inviscid, subsonic flow parameters. The theoretical background, modelling steps and computational results of numerical experiments are discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the influence of electric currents on plastic deformation
Authors: Unger Jaan , Stiemer Marcus , Svendsen Bob , Blum Heribert
Published: January 2007

Electromagnetic sheet metal forming (EMF) is a high‐speed forming process driven by the dynamics of a coupled electromagneticmechanical system. The purpose of the current work is the investigation of a possible reduction in the yield stress due to electric currents. While thermoelastic and viscoplastic effects are well‐understood, the possible influence of electric currents on dislocation motion, generally referred to as the electro‐plastic effect [3], is still an unresolved issue. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prediction of Energy Barriers due to Nucleation in Solid‐to‐Solid Phase–Transitions
Authors: Bartel Thorsten , Hackl Klaus
Published: January 2007

This contribution generally aims at the application of the multiscale‐FEM to problems arising from inhomogeneities of arbitrary shape within a solid matrix material. In the context of our work, the inhomogeneity represents a nucleus of a new solid phase. According to the theory of homogeneous nucleation, the model predicts whether it is energetically preferable to initiate the growth of the nucleus or not. The implementation of this procedure into a micromechanical model for shape‐memory alloys is assumed to be suitable to reconstruct the so‐called stress‐drop after the initiation of phase‐transformation as observed in experiments. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Texture evolution and Swift effect in NiAl
Authors: Glüge Rainer , Böhlke Thomas , Bertram Albrecht
Published: January 2007

Skrotzki et al. [4] performed free end torsion tests on polycrystaline NiAl at 1000 to 1300 °K, where the texture evolution and the Swift effect have been measured. A material model is formulated and implemented to simulate the torsion tests and compared our results to the experimental findings. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiscale FEM in modelling of solution‐precipitation creep
Authors: Ilic Sandra , Hackl Klaus
Published: January 2007

In previous work we proposed a micromechanical model for solution‐precipitation creep based on the minimization of a Lagrangian consisting of elastic power and dissipation. Elastic energy is chosen to be in a standard form but dissipation is strongly adapted to the solution‐precipitation process by introducing two new quantities: the velocity of material transport within the crystallite‐interfaces and the normal velocity of precipitation or solution respectively. Until now only the results for a Voigt‐Sachs model and very simple specimens discretized by FEM were available. Here, our intention is to show results for more realistic examples obtained by using multiscale FEM adapted to the limit case where the ratio between macro and microlevel tends to infinity. In that method the deformation gradient is provided on the macroscale and on the microscale one calculates microfluctuations satisfying periodic boundary conditions. Further calculation yields the effective first Piola‐Kirchhoff stress tensor whose derivative gives the elasticity tensor on the macrolevel. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multi‐Scale Finite‐Volume Method for Elliptic Problems with Heterogeneous Coefficients and Source Terms
Authors: Jenny Patrick , Lunati Ivan
Published: January 2007

Simulation of sub‐surface flow in geologically complex formations is just one example in computational science, where efficient and accurate solutions of heterogeneous elliptic problems are of great interest. Often it is not feasible to resolve the whole range of relevant length scales associated with the spatial distribution of the highly varying coefficients. The MSFV method was originally developed for multi‐phase flow in porous media. In the more general form presented here, it can be applied for solving large elliptic problems in various areas of computational science. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Curl bounds Grad on SO(3)
Authors: Neff P. , Münch I.
Published: January 2007

Let Fp ∈ GL(3) be the plastic deformation from the multiplicative decomposition in elasto‐plasticity. We show that the geometric dislocation density tensor of Gurtin in the form Curl[Fp] · (Fp)T applied to rotations controls the gradient in the sense that pointwise

equation image

This result complements rigidity results (John, Reshetnyak, Friesecke/James/Müller) as well as an associated linearized theorem saying that

equation image
Homogenization Results for Enzymatic Dispersion Processes
Authors: Timofte Claudia
Published: January 2007

The aim of this paper is to study the asymptotic behavior of the solution of a nonlinear problem arising in the modelling of enzyme catalyzed reactions through perforated media. The effective behavior of the solution of such a problem is governed by a new elliptic boundary‐value problem that captures the effect of the enzymatic reactions. The approach we use is the energy method of L. Tartar [4], coupled with monotonicity methods and results from the theory of semilinear problems [2]. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
3D FEA of Size Effects in Deformation of Thin Metallic Films
Authors: Trondl Andreas , Gross Dietmar , Mishnaevsky Leon , Huber Norbert
Published: January 2007

The purpose of this work is to analyze size effects in the deformation occurring during nanoindentation‐tests of thin metallic films on ceramic substrates. It is well known that classical phenomenological theories of plasticity are hardly applicable in cases of very small dimensions of a body [1]. Thus, the dependency of the mechanical behavior of thin films on the thickness can not be studied in the framework of classical theories. In order to simulate numerically the deformation, a specific material model has been chosen which is able to account for size effects. It bases on the theory of ”Mechanism Strain Gradient” (MSG) plasticity [2] in conjunction with the deformation theory of plasticity. The material model has been implemented via the user defined element subroutine (UEL) in the commercial FE code ABAQUS/Standard as a ten‐node tetrahedron‐element. With the developed subroutine the deformation of thin copper films on Si substrates during nanoindentation‐tests has been simulated. Different material models of the indentor (rigid and elastic) as well as different friction conditions between the film and the pyramidal indentor were tested. Furthermore, the influence of an additional oxide layer on the films surface has been analysed. In order to verify the numerical investigations, results from nanoindentation experiments have been used for comparison [4]. The FE simulations for different thicknesses in the range of 100‐600nm showed a very good agreement with the experiments. In particular, the size dependency of the force‐displacement curves, calculated by using the developed subroutine, is in rather good agreement with experiments. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An Approach to Model Partially Premixed Turbulent Combustion withProbability Density Function (PDF) Methods
Authors: Hegetschweiler Michael , Jenny Patrick
Published: January 2007

In turbulent combustion one distinguishes between premixed, non‐premixed and partially premixed combustion. While laminar flamelet models proved to be extremely valuable for a wide range of non‐premixed flame simulations, similar approaches are more problematic in the partially premixed regime. Here the laminar flamelet concept for non‐premixed turbulent combustion simulations is generalized for the partially premixed regime. Similar as in the unsteady flamelet approach, the joint statistics of a progress variable, mixture fraction and scalar dissipation rate is used to obtain the joint statistics of the compositions from pre‐computed flame tables. The required distribution is computed with a joint PDF method and the main differences between the new approach and previous ones, are the pre‐computed tables and the way the evolution of the progress variable is calculated. Instead of evolving 1D flamelets, steady 2D solutions of burning flamelets propagating into unburned mixtures with varying mixture fraction are considered. The location of a fluid particle in this 2D laminar flame is defined by its mixture fraction and a burning time, which are modeled for each computational particle used in the PDF method. Numerical experiments of a turbulent lifted diffusion flame and a premixed Bunsen flame demonstrate that this approach can be employed for a wide range of applications. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exergetic aspects of high‐speed boundary layers
Authors: Jocksch A. , Kleiser L.
Published: January 2007

Exergy is an established concept for evaluating heat cycles. It quantifies the available work that can be extracted from a system. The extension of the classical definition to non‐uniform flow field properties is applied here to high‐speed boundary layers. The destruction of exergy is quantified by the corresponding loss thickness and is evaluated locally. Turbulent fluctuations in this approach are described by their turbulent exergy, which is a generalisation of the concept of turbulent kinetic energy for incompressible flow. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
LES of premixed turbulent combustion using the level set approach
Authors: Kurenkov Oleksiy , Oberlack Martin
Published: January 2007

LES of premixed turbulent combustion is presented based on the level set approach. Level set method is a technique which is especially designed to deal with problems involving topological changes of interfaces, merging interface, singularities and formation of sharp cusps [8]. Our previous work [3] which was performed in RANS‐context contains the level set approach with reinitialization scheme of Sussman et al. [1]. For LES we have developed a completely new algorithm based on the Fast Marching method. It does not need the iterative reinitialization schemes, and, therefore, it quarantees more accurate solution and drastic speed‐up of the computation. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parameterized Scalar Profile Mixing Model for Turbulent Combustion Simulations
Authors: Meyer D. W. , Jenny P.
Published: January 2007

The composition fields in turbulent reacting flows are affected by turbulent transport (macromixing), molecular diffusion (micromixing), and chemical reactions. In the joint velocity‐composition probability density function transport equation the highly non‐linear macromixing and chemical reaction terms appear in closed form. This is a considerable advantage over moment closure methods. Micromixing on the other hand requires modeling and especially for turbulent combustion accurate mixing models are crucial. Our approach to model the mixing of scalars, e.g. species mass fractions or temperature, is based on considering one‐dimensional parameterized scalar profiles (PSP). Here, an extension of the PSP mixing model to inhomogeneous flows is presented. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Lagrangian Joint PDF Approach for Turbulent Premixed Combustion
Authors: Rembold Benjamin , Jenny Patrick
Published: January 2007

A model for premixed turbulent combustion based on a joint velocity probability density function (PDF) method and a progress variable is presented. Compared with other methods employing progress variables, the advantage here is that turbulent mixing of the progress variable requires no modeling. Moreover, by applying scale separation, the Lagrangian framework allows to account for the embedded, quasi laminar flame structure in a very natural way. The numerical results presented here are based on a simple closure of the progress variable source term and it is demonstrated that the new modeling approach is robust and shows the correct qualitative behavior. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)