bluuebunny/crossref_metadata_2025_split huggingface dataset:
Micromechanically‐Based Modelling in Nonlocal Crystal Plasticty
Authors: Becker Martin , Miehe Christian 
Published: November 2004

AbstractWithin purely local descriptions inhomogeneous plastic deformations induce an incompatibility of the intermediate configuration introduced in connection with the multiplicative split of large strain crystal plasticity. Extending the local model by inclusion of higher order gradients of the inelastic deformation restores on the one hand the compatibility of the intermediate configuration and leads on the other hand to size effects in the material behavior in analogy to experimentally observed phenomena. The underlying physical interpretation is the storage of geometrically necessary dislocations (GNDs) for plastically inhomogeneous deformations. We briefly address the relation between deformation incompatibilities and the storage of GNDs. Furthermore we consider the corresponding numerical implementation, validate our approach by means of a benchmark problem and give a short comparison to other dislocation density based as well as rather phenomenological models. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Material Forces in Standard Dissipative Solids obtained from an Incremental Variational Formulation
Authors: Zimmermann Dominik , Miehe Christian 
Published: November 2004

AbstractA variational method for the definition of material forces in standard dissipative solids based on a path‐dependent incremental minimization structure is proposed. The underlying base is provided by incremental variational formulations for standard dissipative solids. For this type of inelastic constitutive response, an incremental stress potential can be constructed by a constitutive minimization principle. Then, the incremental boundary value problem of a deformed inelastic body is governed by a minimization principle. In this context dual variational settings for the definition of both the physical as well as the material forces are presented. This yields to the definition of material forces as the sensitivity of work with respect to change of Lagrangian, i.e. material coordinates. An application of the material force method to the description of elastic‐plastic fracture mechanics is given. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prenatal diagnosis for arginase deficiency by second‐trimester fetal erythrocyte arginase assay and first‐trimester ARG1 mutation analysis
Authors: Korman Stanley H. , Gutman Alisa , Stemmer Edia , Kay Barrie S. , Ben‐Neriah Ziva , Zeigler Marsha 
Published: November 2004

AbstractHyperargininemia is a progressive neurometabolic disorder caused by deficiency of hepatic cytosolic arginase I, resulting from mutations in the ARG1 gene. We diagnosed arginase deficiency in a three‐year‐old male child of first‐cousin Palestinian Arab parents. Prenatal diagnosis of an unaffected fetus was achieved in the second trimester of a subsequent pregnancy by cordocentesis and analysis of arginase activity in fetal erythrocytes. ARG1 mutation analysis in the proband revealed homozygosity for a deletion of 10 753 bp extending from the first intron to beyond the poly (A) site of the gene. This is the first gross deletion in the ARG1 gene to be identified and the first mutation to be described in an arginase‐deficient patient of this ethnic origin. The identification of the ARG1 deletion in this family enabled first‐trimester prenatal diagnosis in a subsequent pregnancy by multiplex PCR analysis performed on chorionic villous DNA. Copyright © 2004 John Wiley & Sons, Ltd.
Influences of hot stretch ratio on essential work of fracture ofin‐situmicrofibrillar poly(ethylene terephthalate)/polyethylene blends
Authors: Li Zhong‐Ming , Xie Bang‐Hu , Huang Rui , Fang Xiang‐Ping , Yang Ming‐Bo 
Published: November 2004

AbstractAnin‐situmicrofibrillar blend based on poly(ethylene terephthalate) (PET) and polyethylene (PE) was fabricated through slit die extrusion, hot stretching, and quenching. The morphological characteristics of the PET phase, such as diameter and its distribution, which were observed after the matrix was etched away, appear to be dependent on the hot stretch ratio at a fixed blend composition. The increase of the hot stretching ratio makes the PET particles change from spheres and ellipsoids to rodlike particles, and finally to well‐defined microfibers. The fracture toughness of thein‐situmicrofibrillar blend was evaluated using deeply double‐edge notched tension (DDENT) specimens according to the essential work of fracture procedure. Initially, the increase of hot stretch ratio makes the specific essential work of fracture (we) rise. A maximum we appears at 25.4. Further increase of hot stretch ratio causes a slightdecrease ofwe. On the other hand, it shows that lower hot stretch ratios make the specific non‐essential work of fracture (wp) rise slightly. As it exceeds 6.4,wpdecreases substantially. It was believed that the characteristics of the PET domains were responsible for the fracture behaviors of thein‐situmicrofibrillar blend. Polym. Eng. Sci. 44:2165–2173, 2004. © 2004 Society of Plastics Engineers.
Design of calibrators for extruded profiles. Part I: Modeling the thermal interchanges
Authors: Nóbrega J. M. , Carneiro O. S. , Covas J. A. , Pinho F. T. , Oliveira P. J. 
Published: November 2004

AbstractThe parameters influencing the calibration/cooling stage of profile extrusion are discussed, and a numerical finite‐volume method code to model the heat transfer is described and validated. For this purpose, the numerical predictions are compared with the analytical solution of a simple problem, with results available in the literature and with those produced by a commercial software. The routines developed are then used to identify the main process parameters and boundary conditions and to estimate their relative importance. The investigation clearly shows the advantages of using several calibrators separated by annealing zones, relative to a single calibrator of the same total length, and the large impact of the contact resistance between extrudate and cooling unit while showing negligible impact of other boundary conditions. A decrease of the extrudate velocity is seen to be also an effective control parameter, but it decreases the production rates. Polym. Eng. Sci. 44:2216–2228, 2004. © 2004 Society of Plastics Engineers.
New experimental method for determination of effective diffusion coefficient of blowing agents in polyurethane foams
Authors: Modesti M. , Lorenzetti A. , Dall'Acqua C. 
Published: November 2004

AbstractThe effective diffusion coefficients of novel, environmentally friendly, hydrofluorocarbon (HFC) blowing agents for polyurethane foam production were measured. The method was based on gas chromatography and infrared spectroscopy measurements. The accuracy and reliability of the procedure developed were confirmed by comparisons of experimental and the predicted thermal aging curves. The slope of the aging curves (i.e., the change in thermal conductivity with time) depended only on the effective diffusion coefficients. The effective diffusion coefficients of the new HFC blowing agents were close to those of conventional hydrochlorofluorocarbon (HCFC) blowing agents, and the aging behavior of foams produced from HFC or HCFC blowing agents were similar. Polym. Eng. Sci. 44:2229–2239, 2004. © 2004 Society of Plastics Engineers.
A time‐scale approach for analysis of coalescence in processing flows
Authors: Perilla Jairo E. , Jana Sadhan C. 
Published: November 2004

AbstractCoalescence of droplets in flow through capillary dies and in the filling of strip molds was investigated using experiments and time‐scale analysis. The time scales of droplet approach, droplet‐droplet interactions, and fluid drainage were compared with the time scales of flow in order to predict the extent of coalescence in each case. In the case of capillary dies, coalescence took place predominantly in the zones away from the die wall and away from the die axis, and the expanse of the coalescence zone increased with blend composition and decreased with mean shear rate. In the case of mold filling, droplet coalescence took place after the polymer flowed a characteristic distance along the mold. A semiquantitative agreement was found between the predictions and the experimental results obtained using blends of polypropylene and polystyrene. In addition to larger‐diameter droplets, long fibrils, formed by stringing of coalescing droplets, were observed. Polym. Eng. Sci. 44:2254–2265, 2004. © 2004 Society of Plastics Engineers.
Study of the miscibility and mechanical properties of NBR/HNBR blends
Authors: Hussein Ibnelwaleed A. , Chaudhry Rehan A. , Abu Sharkh Basel F. 
Published: November 2004

AbstractIn this study, hydrogenated acrylonitrile butadiene rubber (HNBR, ZETPOL‐2010L) and nitrile butadiene rubber (NBR, NIPOL‐DN4555) were blended at different ratios in a Haake melt blender at 130°C. The HNBR and the NBR were of very similar acrylonitrile content and Mooney viscosity. The melt miscibility and solid‐state properties were investigated by rheological, thermal, and mechanical testing and scanning electron microscopy (SEM) techniques. The dynamic viscosity of the blends followed the log‐additivity rule, while the flow activation energy closely followed the inverse additivity rule. On the other hand, the storage modulus showed synergistic effects at all compositions, suggesting the presence of emulsion morphology at both ends of the composition range. For the 50/50 HNBR/NBR blend, the SEM micrographs suggest a uniform elongated structure. The thermal analysis showed the presence of two glass transitions, representing the pure components, at all blend ratios, suggesting the absence of segmental miscibility of the blends. The small‐strain mechanical properties such as tensile modulus and yield stress followed linear additivity. However, HNBR and HNBR‐rich blends were observed to strain harden at a rate higher than that of NBR. Induced crystallization of HNBR was suggested to be the reason for the strain hardening. The different rheological, thermal, and mechanical testing techniques agree in suggesting that the structurally similar HNBR and NBR are not thermodynamically miscible but mechanically compatible. Polym. Eng. Sci. 44:2346–2352, 2004. © 2004 Society of Plastics Engineers.
Rapid and selective identification of molecular species in phosphatidylcholine and sphingomyelin by conditional neutral loss scanning and MS3
Authors: Houjou Toshiaki , Yamatani Kotoko , Nakanishi Hiroki , Imagawa Masayoshi , Shimizu Takao , Taguchi Ryo 
Published: November 2004

AbstractAnalyses of molecular species of phospholipids containing choline (Ch), such as phosphatidylcholine (PC) and sphingomyelin (SM), are reported. Neutral loss scanning was applied for the selective detection of these lipids using a quadrupole‐linear ion trap mass spectrometer. By using ammonium formate as an elution buffer, both PC and SM were detected as [M+HCOO]− ions in the negative ion mode. Upon collisional activation, the [M+HCOO]− adduct ions underwent facile elimination of HCO2, to yield an ion which, in turn, readily underwent collisional‐induced dissociation (CID) to eliminate CH3 to yield an [M–CH3]− ion. By selecting the proper conditions for scanning for neutral loss of 60 Da (HCO2+CH3), SM species were identified separately from PCs. Further, by selection of this [M–CH3]− ion as the precursor ion, the identities of the fatty acyl chains of PC species can be effectively obtained by MS3 experiments. Furthermore, by the MS3 analyses of [M–CH3]− specifically obtained from SM molecules, identification of sphingosine or sphinganine derivatives and their N‐acyl species can also be effectively obtained. This systematic analysis of PCs and SMs by conditional neutral loss scanning, with subsequent analyses by MS3, using a linear ion trap mass spectrometer in the negative ion mode, appears to be a very effective and sensitive method. Further, MS/MS in the positive ion mode at relatively low collision energy was also effective for the identification of positional specificities in individual molecular PC species from their lysoPC‐related fragments. The present paper deals only with qualitative identification of individual molecular species, and the related quantitative studies are now underway. Copyright © 2004 John Wiley & Sons, Ltd.
Influence analysis for linear mixed‐effects models
Authors: Demidenko Eugene , Stukel Therese A. 
Published: November 2004

AbstractIn this paper, we extend several regression diagnostic techniques commonly used in linear regression, such as leverage, infinitesimal influence, case deletion diagnostics, Cook's distance, and local influence to the linear mixed‐effects model. In each case, the proposed new measure has a direct interpretation in terms of the effects on a parameter of interest, and collapses to the familiar linear regression measure when there are no random effects. The new measures are explicitly defined functions and do not necessitate re‐estimation of the model, especially for cluster deletion diagnostics. The basis for both the cluster deletion diagnostics and Cook's distance is a generalization of Miller's simple update formula for case deletion for linear models. Pregibon's infinitesimal case deletion diagnostics is adapted to the linear mixed‐effects model. A simple compact matrix formula is derived to assess the local influence of the fixed‐effects regression coefficients. Finally, a link between the local influence approach and Cook's distance is established. These influence measures are applied to an analysis of 5‐year Medicare reimbursements to colon cancer patients to identify the most influential observations and their effects on the fixed‐effects coefficients. Copyright © 2004 John Wiley & Sons, Ltd.
Eine Vollglaskonstruktion – Möglichkeiten und Probleme
Authors: Werner Frank 
Published: November 2004

AbstractVorgestellt werden der Entwurf und die Realisierung einer zweigeschossigen Glaskonstruktion, die konsequent auf Stahltrag‐ und Sicherungselemente verzichtet. Stützen und Träger sollten die Transparenz der Hülle nicht beeinträchtigen und sind deshalb aus Glas. Die Gesamttragwirkung wird über die Verklebungen der Bauelemente untereinander und mit dem angrenzenden Baukörper gewährleistet. Die Einleitung örtlicher Lasten in den Rand der Wandscheiben ohne zusätzliche konstruktive Elemente wird numerisch und experimentell untersucht.Dieser Experimentalbau dient dazu, konstruktive Lösungen zu testen und fundierte Aussagen zur Nutzung und zu den Kosten zu erhalten.
Decision‐making capacity and disaster research
Authors: Rosenstein Donald L. 
Published: November 2004

AbstractThe extent to which victims of a disaster are able to make capacitated and voluntary decisions to enroll in research is an important and virtually unexplored question. Although there are no compelling data to suggest that experiencing a severe trauma, in and of itself, renders all or even most individuals incapable of making autonomous decisions, the assessment of decision‐making capacity (DMC) for research participation warrants serious consideration. This paper provides a framework for and procedural approach to the assessment of DMC in research with individuals exposed to disaster. Particular attention is paid to the implementation of additional safeguards to protect subjects who are vulnerable by virtue of impaired DMC. Recommendations are offered to clinical investigators, ethical review boards, and policymakers with regard to the design, review, and conduct of research in the aftermath of disaster.
Platelet–cancer interactions: mechanisms and pharmacology of tumour cell‐induced platelet aggregation
Authors: Jurasz Paul , Alonso‐Escolano David , Radomski Marek W 
Published: November 2004

During haematogenous metastasis, cancer cells migrate to the vasculature and interact with platelets resulting in tumour cell‐induced platelet aggregation (TCIPA). We review:

The biological and clinical significance of TCIPA;
Molecular mechanisms involved in platelet aggregation by cancer cells;
Strategies for pharmacological regulation of these interactions.

We conclude that pharmacological regulation of platelet–cancer cell interactions may reduce the impact of TCIPA on cancer biology.British Journal of Pharmacology (2004) 143, 819–826. doi:10.1038/sj.bjp.0706013
KATP‐channel‐induced vasodilation is modulated by the Na,K‐pump activity in rabbit coronary small arteries
Authors: Glavind‐Kristensen Marianne , Matchkov Vladimir , Hansen Vibeke Brogaard , Forman Axel , Nilsson Holger , Aalkjær Christian 
Published: November 2004

The purpose of the study was to evaluate the importance of the Na,K‐pump in relaxations induced by KATP‐channel openers in rabbit coronary small arteries.
Arterial segments were mounted in myographs for recording of isometric tension. Whole‐cell patch clamp was used to assess KATP‐channel currents in isolated smooth muscle cells from the arteries.
In arteries preconstricted with the thromboxane A2 analogue U46619 pinacidil and cromakalim induced concentration‐dependent relaxations. In arteries preconstricted with potassium (124 mM) only high concentrations of pinacidil had a small relaxant effect.
In arteries preconstricted with U46619 pinacidil‐induced relaxations were unaffected by pretreatment with Nω‐nitro‐L‐arginine (L‐NNA) and only slightly reduced after mechanical removal of the endothelium.
Pinacidil induced relaxations were not significantly affected by 1 μM glibenclamide. However, the relaxations were partly inhibited in potassium‐free media and by 1 μM ouabain.
In contrast, the concentration‐dependent relaxation to cromakalim was partly blocked by 1 μM glibenclamide and partly by 1 μM ouabain and when both drugs were present the inhibition increased.
Ouabain (1 μM) and glibenclamide (1 μM) each partly inhibited an ATP‐sensitive current induced by pinacidil and cromakalim. In the presence of both inhibitors a greater inhibition was seen. When the solution in the patch pipette was sodium‐free the current was reduced and ouabain had no effect.
The study suggests that the relaxation to cromakalim and most likely pinacidil is mediated through opening of KATP channels. Inhibition of the Na,K‐pump, however, may change the local environment for the KATP channels (i.e. increases the ATP/ADPratio and/or decreases the transmembrane potassium gradient), which partly prevents the activation of the KATP‐channel current.

British Journal of Pharmacology (2004) 143, 872–880. doi:10.1038/sj.bjp.0706016
Selective inhibition of sodium–calcium exchanger by SEA‐0400 decreases early and delayed afterdepolarization in canine heart
Authors: Nagy Zsolt A , Virág László , Tóth András , Biliczki Péter , Acsai Károly , Bányász Tamás , Nánási Péter , Papp Julius Gy , Varró András 
Published: November 2004

The sodium–calcium exchanger (NCX) was considered to play an important role in arrhythmogenesis under certain conditions such as heart failure or calcium overload. In the present study, the effect of SEA‐0400, a selective inhibitor of the NCX, was investigated on early and delayed afterdepolarizations in canine ventricular papillary muscles and Purkinje fibres by applying conventional microelectrode techniques at 37°C. The amplitude of both early and delayed afterdepolarizations was markedly decreased by 1 μM SEA‐0400 from 26.6±2.5 to 14.8±1.8 mV (n=9, P<0.05) and from 12.5±1.7 to 5.9±1.4 mV (n=3, P<0.05), respectively. In enzymatically isolated canine ventricular myocytes, SEA‐0400 did not change significantly the L‐type calcium current and the intracellular calcium transient, studied using the whole‐cell configuration of the patch‐clamp technique and Fura‐2 ratiometric fluorometry. It is concluded that, through the reduction of calcium overload, specific inhibition of the NCX current by SEA‐0400 may abolish triggered arrhythmias.British Journal of Pharmacology (2004) 143, 827–831. doi:10.1038/sj.bjp.0706026
Kinetic and structural optimization to catalysis at low temperatures in a psychrophilic cellulase from the Antarctic bacterium Pseudoalteromonas haloplanktis
Authors: GARSOUX Geneviève , LAMOTTE Josette , GERDAY Charles , FELLER Georges 
Published: November 2004

The cold-adapted cellulase CelG has been purified from the culture supernatant of the Antarctic bacterium Pseudoalteromonas haloplanktis and the gene coding for this enzyme has been cloned, sequenced and expressed in Escherichia coli. This cellulase is composed of three structurally and functionally distinct regions: an N-terminal catalytic domain belonging to glycosidase family 5 and a C-terminal cellulose-binding domain belonging to carbohydrate-binding module family 5. The linker of 107 residues connecting both domains is one of the longest found in cellulases, and optimizes substrate accessibility to the catalytic domain by drastically increasing the surface of cellulose available to a bound enzyme molecule. The psychrophilic enzyme is closely related to the cellulase Cel5 from Erwinia chrysanthemi. Both kcat and kcat/Km values at 4 °C for the psychrophilic cellulase are similar to the values for Cel5 at 30–35 °C, suggesting temperature adaptation of the kinetic parameters. The thermodynamic parameters of activation of CelG suggest a heat-labile, relatively disordered active site with low substrate affinity, in agreement with the experimental data. The structure of CelG has been constructed by homology modelling with a molecule of cellotetraose docked into the active site. No structural alteration related to cold-activity can be found in the catalytic cleft, whereas several structural factors in the overall structure can explain the weak thermal stability, suggesting that the loss of stability provides the required active-site mobility at low temperatures.
New insights into the structure–function relationships of Rho-associated kinase: a thermodynamic and hydrodynamic study of the dimer-to-monomer transition and its kinetic implications
Authors: DORAN John D. , LIU Xun , TASLIMI Paul , SAADAT Ahmad , FOX Ted 
Published: November 2004

The effect of the length of ROCK (Rho-associated kinase) on its oligomerization state has been investigated by analysing full-length protein and four truncated constructs using light-scattering and analytical ultracentrifugation methods. Changes in size correlate with the kinetic properties of the kinase. Sedimentation velocity, sedimentation equilibrium and light-scattering data analyses revealed that protein constructs of size Ser6–Arg415 and larger exist predominantly as dimers, while smaller constructs are predominantly monomeric. The amino acid segments comprising residues 379–415 and 47–78 are shown to be necessary to maintain the dimeric ROCK structure. kcat values ranged from 0.7 to 2.1 s−1 and from 1.0 to 5.9 s−1 using ROCK peptide (KKRNRTLSV) and the 20000 Da subunit of myosin light chain respectively as substrate, indicating that the effect of the ROCK oligomerization state on the kcat is minor. Values of ATP Km for monomeric constructs were increased by 50–80-fold relative to the dimeric constructs, and Ki comparisons using the specific competitive ROCK inhibitor Y-27632 also showed increases of at least 120-fold, demonstrating significant perturbations in the ATP binding site. The corresponding Km values for the ROCK peptide and myosin light chain substrates increased in the range 1.4–16-fold, demonstrating that substrate binding is less sensitive to the ROCK oligomerization state. These results show that the oligomerization state of ROCK may influence both its kinase activity and its interactions with inhibitors, and suggest that the dimeric structure is essential for normal in vivo function.