bluuebunny/crossref_metadata_2025_split huggingface dataset:
Equilibrium problem for thermoelectroconductive body with the Signorini condition on the boundary
Authors: Hömberg D. , Khludnev A. M. 
Published: January 2005

AbstractWe investigate a boundary value problem for a thermoelectroconductive body with the Signorini condition on the boundary, related to resistance welding. The mathematical model consists of an energy‐balance equation coupled with an elliptic equation for the electric potential and a quasistatic momentum balance with a viscoelastic material law. We prove the existence of a weak solution to the model by using the Schauder fixed point theorem and classical results on pseudomonotone operators. Copyright © 2001 John Wiley & Sons, Ltd.
Inverse scattering for the non‐linear Schrödinger equation: Reconstruction of the potential and the non‐linearity
Authors: Weder Ricardo 
Published: January 2005

AbstractIn this paper we consider the inverse scattering problem for the non‐linear Schrödinger equation on the line

\def\dr{{\rm d}}$$i{\partial\over\partial t}u(t,x)=‐{\dr^2\over\dr x^2}u(t,x)+V_0(x)u(t,x)+\sum_{j=1}^{\infty}V_j(x)|u|^{2(j_0+j)}u(t,x)$$\nopagenumbers\end

We prove, under appropriate conditions, that the small‐amplitude limit of the scattering operator determines uniquely Vj, j=0,1,… . Our proof gives also a method for the reconstruction of the Vj, j=0,1,… . Copyright © 2001 John Wiley & Sons, Ltd.
Complete multinuclear magnetic resonance analysis of heterophospholanes and their sulfur, selenium and borane adducts
Authors: Peralta‐Cruz Javier , Bakhmutov Vladimir I. , Ariza‐Castolo Armando 
Published: January 2005

Abstract1H, 11B, 13C, 15N, 31P and 77Se NMR spectra were obtained for 1,3‐(dioxa, oxaza or diaza)‐2‐phospholanes and their sulfur, selenium and borane adducts. The relative sign of the 3J(1H, 31P)/2J(13C, 31P) coupling constants was found to be positive in the sulfur and selenium adducts for the methylene and methyl groups. Conversely, for the compound with a phosphorus lone pair and in the borane adducts this sign changes for the methylene groups. It was shown that the 31P NMR spectra recorded by the CPMG or INEPT‐HEED pulse sequences can be used for observation of the 15N–31P coupling constants. In all the investigated compounds the spin–lattice relaxation of 31P is controlled by the spin‐rotation mechanism. The dipole–dipole 31P–11B interactions can provide less than 20% of the relaxation rate in compounds containing the BH3 group. The transverse 31P relaxation is dominated by the scalar contribution. Copyright © 2001 John Wiley & Sons, Ltd.
Failure envelopes and plastic potentials for eccentrically loaded surface footings on undrained soil
Authors: Fraser Bransby M. 
Published: January 2005

AbstractThe failure envelope in V–M space for surface foundations on undrained material under eccentric loading can be determined using an extended version of the scaling (or effective area) concept of Meyerhof. A similar displacement transformation allows production of the plastic potential. The two‐dimensional finite element analyses of fully attached foundations subject to combined vertical (V) and moment (M) loading have been used to calculate appropriate scaling points for deduction of the failure envelope and plastic potential. Failure envelopes and plastic potentials are presented for footings on uniform and non‐uniform undrained material and it is seen that the equivalent ‘critical state’ or ‘parallel point’ lies slightly beneath the peak moment capacity. For accurate prediction of failure envelopes for footings on non‐uniform strength soil, consideration must be made of the apparent reduction of the soil heterogeneity as the area of footing in contact with the soil decreases. Copyright © 2001 John Wiley & Sons, Ltd.
Adaptivity in computational mechanics of concrete structures
Authors: Lackner Roman , Mang Herbert A. 
Published: January 2005

AbstractThe paper contains a report on the development of an adaptive finite element (FE) calculation scheme for the analysis of concrete structures with special emphasis on softening in consequence of cracking. For the description of the material behavior of concrete, a multi‐surface plasticity model is employed. The opening of cracks is controlled by means of the so‐called fictitious crack concept. Difficulties arising from this concept when employed in error‐controlled adaptivity are discussed in detail. As a remedy, the consideration of mesh alignment during the design of the new mesh is proposed. The usefulness of the developed adaptive calculation scheme is demonstrated by means of two example problems. Copyright © 2001 John Wiley & Sons, Ltd.
Friction and degradation of rock joint surfaces under shear loads
Authors: Homand F. , Belem T. , Souley M. 
Published: January 2005

AbstractThe morpho‐mechanical behaviour of one artificial granite joint with hammered surfaces, one artificial regularly undulated joint and one natural schist joint was studied. The hammered granite joints underwent 5 cycles of direct shear under 3 normal stress levels ranging between 0.3 and 4 MPa. The regularly undulated joint underwent 10 cycles of shear under 6 normal stress levels ranging between 0.5 and 5 MPa and the natural schist replicas underwent a monotonics shear under 5 normal stress levels ranging between 0.4 and 2.4 MPa. These direct shear tests were performed using a new computer‐controlled 3D‐shear apparatus. To characterize the morphology evolution of the sheared joints, a laser sensor profilometer was used to perform surface data measurements prior to and after each shear test. Based on a new characterization of joint surface roughness viewed as a combination of primary and secondary roughness and termed by the joint surface roughness, SRs, one parameter termed ‘joint surface degradation’, Dw, has been defined to quantify the degradation of the sheared joints. Examinations of SRs and Dw prior to and after shearing indicate that the hammered surfaces are more damaged than the two other surfaces. The peak strength of hammered joint with zero‐dilatancy, therefore, significantly differs from the classical formulation of dilatant joint strength. An attempt has been made to model the peak strength of hammered joint surfaces and dilatant joints with regard to their surface degradation in the course of shearing and two peak strength criteria are proposed. Input parameters are initial morphology and initial surface roughness. For the hammered surfaces, the degradation mechanism is dominant over the phenomenon of dilatancy, whereas for a dilatant joint both mechanisms are present. A comparison between the proposed models and the experimental results indicates a relatively good agreement. In particular, compared to the well‐known shear strength criteria of Ladanyi and Archambault or Saeb, these classical criteria significantly underestimate and overestimate the observed peak strength, respectively, under low and high normal stress levels. In addition and based on our experimental investigations, we put forward a model to predict the evolution of joint morphology and the degree of degradation during the course of shearing.Degradations of the artificial undulated joint and the natural schist joint enable us to verify the proposed model with a relatively good agreement. Finally, the model of Ladanyi and Archambault dealing with the proportion of total joint area sheared through asperities, as, once again, tends to underestimate the observed degradation. Copyright © 2001 John Wiley & Sons, Ltd.
Cyclic macro‐element for soil–structure interaction: material and geometrical non‐linearities
Authors: Cremer Cécile , Pecker Alain , Davenne Luc 
Published: January 2005

AbstractThis paper presents a non‐linear soil–structure interaction (SSI) macro‐element for shallow foundation on cohesive soil. The element describes the behaviour in the near field of the foundation under cyclic loading, reproducing the material non‐linearities of the soil under the foundation (yielding) as well as the geometrical non‐linearities (uplift) at the soil–structure interface. The overall behaviour in the soil and at the interface is reduced to its action on the foundation. The macro‐element consists of a non‐linear joint element, expressed in generalised variables, i.e. in forces applied to the foundation and in the corresponding displacements. Failure is described by the interaction diagram of the ultimate bearing capacity of the foundation under combined loads. Mechanisms of yielding and uplift are modelled through a global, coupled plasticity–uplift model.The cyclic model is dedicated to modelling the dynamic response of structures subjected to seismic action. Thus, it is especially suited to combined loading developed during this kind of motion. Comparisons of cyclic results obtained from the macro‐element and from a FE modelization are shown in order to demonstrate the relevance of the proposed model and its predictive ability. Copyright © 2001 John Wiley & Sons, Ltd.
The influence of a non‐associated flow rule on the calculation of the factor of safety of soil slopes
Authors: Wang Yu‐Jie , Yin Jian‐Hua , Lee C. F. 
Published: January 2005

AbstractThis paper presents a method that incorporates a non‐associated flow rule into the limit analysis to investigate the influence of the dilatancy angle on the factor of safety for the slope stability analysis. The proposed method retain's the advantage of the upper bound method, which is simple and has no stress involvement in the calculation of the energy dissipation and the factor of safety. Copyright © 2001 John Wiley & Sons, Ltd.
Computations for bang–bang constrained optimal control using a mathematical programming formulation
Authors: Kaya C. Yalçın , Lucas Stephen K. , Simakov Sergey T. 
Published: January 2005

AbstractAn algorithm is proposed to solve the problem of bang–bang constrained optimal control of non‐linear systems with free terminal time. The initial and terminal states are prescribed. The problem is reduced to minimizing a Lagrangian subject to equality constraints defined by the terminal state. A solution is obtained by solving a system of non‐linear equations. Since the terminal time is free, time‐optimal control is given a special emphasis. Second‐order sufficient conditions of optimality are also stated. The algorithm is demonstrated by a detailed study of the switching structure for stabilizing the F–8 aircraft in minimum time, and other examples. Copyright © 2005 John Wiley & Sons, Ltd.
Effect of exfoliation on poly(styrene‐co‐acrylonitrile)/montmorillonite nanocomposite flammability
Authors: Stretz H. A. , Wootan M. W. , Cassidy P. E. , Koo J. H. 
Published: January 2005

AbstractMontmorillonite clays (MMT) have shown potential as non‐halogenated fire retardants in polymer blends, but the effect of morphology of the resulting nanocomposite is not well understood. In this article MMT blends are studied in a styrene‐acrylonitrile copolymer (SAN) matrix to get structure–property relationships relating to the more complex problem of flame retardancy (FR) of acrylonitrile‐butadiene‐styrene copolymer (ABS) computer housings. The morphology observed in SAN/MMT blends using twin screw extrusion was complex, and was affected by the compatibilizing amine head group substituent size, the amine tail group length, and the amine exchange ratio. However, the morphology did not affect flammability properties significantly. The most important determinant of FR properties was clay loading. Peak heat release rate was reduced up to 49% at a loading of about 12% organoclay, using a 2‐ethylhexyl dimethyl hydrogenated tallow ammonium surfactant. Backside temperatures were measured during FR tests, and significant reductions in maximum heat soak temperature and time to reach heat soak temperature were noted as exfoliation increased, supporting the theory that the clays have an insulative effect. Copyright © 2005 John Wiley & Sons, Ltd.
Investigating morphology and deformation behavior of multilayered PC/PET composites
Authors: Adhikari R. , Lebek W. , Godehardt R. , Henning S. , Michler G. H. , Baer E. , Hiltner A. 
Published: January 2005

AbstractUsing transmission electron microscopy (TEM) and scanning force microscopy (SFM), this work deals with morphology and micromechanical deformation behavior of coextruded multilayers comprising alternating layers of polycarbonate (PC) and polyethylene terephthalate (PET). The multilayered composites were found to consist of macroscopically aligned continuous layers of the constituents having nearly uniform thickness. On annealing the samples, the PET layers were found to undergo cold‐crystallization and to form lamellar crystals independent of thickness of individual layers. Under the influence of tensile loading, mechanical properties of the composites was found to be intermediate between that of the constituent homopolymers. The components of the multilayered composites deformed in homogeneous manner at high strains without forming localized deformation zones. Copyright © 2005 John Wiley & Sons, Ltd.
Effects of src kinase and TGFβ1 on the differentiation and morphogenesis of MDCK cells grown in three‐dimensional collagen and Matrigel environments†
Authors: Rahikkala Mira , Sormunen Raija , Eskelinen Sinikka 
Published: January 2005

AbstractThis study attempted to analyse in detail the effect of src kinase on the growth and differentiation of MDCK cells in different extracellular matrix (ECM) environments. A method was developed to label the membrane proteins in situ and the distribution of cytoskeletal and junctional proteins was visualized in three‐dimensional cell complexes, using optical sections generated by confocal microscopy. Independently of the ECM, non‐transformed MDCK cells formed differentiated cell cysts with one or a few lumina, with the apical side facing the lumen; ZO‐1 was expressed at the tight junctions close to the apical side and β‐catenin, E‐cadherin and fodrin along the entire lateral walls. The phenotype of src kinase activated MDCK cells was strongly dependent on the ECM and varied from an irregular cluster in collagen I, to tubular structures in laminin or proteoglycans, and finally to a polarized cell cyst in Matrigel. In collagen I, E‐cadherin and β‐catenin were seen partially along the lateral walls and partially in the cytoplasm of src‐transformed MDCK cells; fodrin was released into the cytoplasm and ZO‐1 was not visualized. When the src‐transformed cells were cultivated in Matrigel, their junctional proteins were recruited to the cell membranes and ZO‐1 reappeared at the apical face. Thus, the components of Matrigel could overcome the deleterious effect of src on the polarity of MDCK cells. TGFβ1, together with its receptors and other soluble factors in Matrigel, were responsible for the induction of differentiation. The results show that tyrosine phosphorylation sensitizes the epithelial MDCK cells to ECM and TGFβ1. Copyright © 2001 John Wiley & Sons, Ltd.
Expression of angiogenesis‐related molecules in plexiform lesions in severe pulmonary hypertension: evidence for a process of disordered angiogenesis
Authors: Tuder Rubin M. , Chacon Mati , Alger Lori , Wang Jun , Taraseviciene‐Stewart Laimute , Kasahara Yasunori , Cool Carlyne D. , Bishop Anne E. , Geraci Mark , Semenza Gregg L. , Yacoub Magdi , Polak Julia M. , Voelkel Norbert F. 
Published: January 2005

AbstractPulmonary arteries of patients with severe pulmonary hypertension (SPH) presenting in an idiopathic form (primary PH‐PPH) or associated with congenital heart malformations or collagen vascular diseases show plexiform lesions. It is postulated that in lungs with SPH, endothelial cells in plexiform lesions express genes encoding for proteins involved in angiogenesis, in particular, vascular endothelial growth factor (VEGF) and those involved in VEGF receptor‐2 (VEGFR‐2) signalling. On immunohistochemistry and in situ hybridization, endothelial cells in the plexiform lesions expressed VEGF mRNA and protein and overexpressed the mRNA and protein of VEGFR‐2, and the transcription factor subunits HIF‐1α and HIF‐1β of hypoxia inducible factor, which are responsible for the hypoxia‐dependent induction of VEGF. When compared with normal lungs, SPH lungs showed decreased expression of the kinases PI3 kinase and src, which, together with Akt, relay the signal transduction downstream of VEGFR‐2. Because markers of angiogenesis are expressed in plexiform lesions in SPH, it is proposed that these lesions may form by a process of disordered angiogenesis. Copyright © 2001 John Wiley & Sons, Ltd.
Analysis of single EBER‐positive and negative tumour cells in EBV‐harbouring B‐cell non‐Hodgkin lymphomas
Authors: Hänel Patricia , Hummel Michael , Anagnostopoulos Ioannis , Stein Harald 
Published: January 2005

AbstractIn situ hybridization for Epstein–Barr virus (EBV) encoded small nuclear RNAs (EBERs) is the method of choice for the detection of EBV infection at the single cell level. With the application of this technique it was shown that non‐Hodgkin's lymphomas of B‐cell type may be associated with an EBV infection of tumour cells. Interestingly, in many EBV‐positive cases, only a proportion of the tumour cell population has been found to be EBER‐positive. To clarify whether EBV is absent or whether EBER gene expression is downregulated in EBER‐negative tumour cells, single EBER‐positive and negative tumour cells were isolated from paraffin sections from four B‐cell non‐Hodgkin's lymphoma cases with partial EBER expression in the neoplastic cells. These single cells were then screened for the presence of EBV DNA by a nested single cell PCR. EBV DNA was undetectable in all but one of the 86 EBER‐negative cells, whereas in the EBER‐positive cells EBV‐specific DNA amplificates could be generated following single cell PCR. This finding prompts the conclusion that the inability to detect EBERs in a proportion of tumour cells is not due to a down‐regulation of gene expression but to a real absence of EBV from these cells. This partial absence of EBV is thought to be caused by a loss of the EBV episomes during cell division, rather than by infection of only a proportion of the tumour cells. Copyright © 2001 John Wiley & Sons, Ltd.
Liver metastases from colorectal adenocarcinomas grow in three patterns with different angiogenesis and desmoplasia
Authors: Vermeulen Peter B. , Colpaert Cecile , Salgado Roberto , Royers Ruben , Hellemans Hilde , Van den Heuvel Eva , Goovaerts Gerda , Dirix Luc Y. , Van Marck Eric 
Published: January 2005

AbstractThe liver is a highly vascularized organ which frequently hosts metastases in patients with colorectal adenocarcinomas. The hypothesis of this study is that the hypoxic drive of angiogenesis might be minimal or absent in those growing liver metastases which are capable of preserving the stromal structure, including the numerous sinusoidal blood vessels. Representative paraffin sections of liver metastases from 26 patients with colorectal adenocarcinoma were investigated. Three different growth patterns were found. In the desmoplastic and in the pushing growth patterns (42% and 46% of all metastases, respectively), the architecture of the liver parenchyma was not preserved. In the replacement growth pattern (12% of all cases), the reticulin pattern of the liver parenchyma was conserved within the metastases at the tumour–liver parenchyma interface. The endothelial cells of the blood vessels near the interface in the metastases of the replacement type did not express CD34, nor were they surrounded by alpha‐smooth muscle actin‐positive mural cells. In the desmoplastic and in the pushing growth patterns, 23% and 52% of all blood vessels in this area were covered by pericytes. The fraction of proliferating endothelial cells was low in the metastases with a desmoplastic or a replacement growth pattern (about 3%), compared with metastases with a pushing growth pattern (11%). Tumour cell apoptosis was highest in the pushing‐type metastases and was inversely correlated with microvessel density in liver metastases. The ratio of the proliferating tumour cell fraction and the proliferating endothelial cell fraction, roughly representing the degree of angiogenesis‐dependent growth, was three‐ to four‐fold higher in the replacement‐type metastases compared with the other metastases. In summary, the present study has demonstrated that liver metastases are a heterogeneous group, with different growth patterns which predict the fraction of immature blood vessels, the fraction of proliferating endothelial cells, and the fraction of apoptotic tumour cells. The replacement growth pattern expands with minimal angiogenesis by co‐opting the stroma with the sinusoidal blood vessels of the liver. Copyright © 2001 John Wiley & Sons, Ltd.
An analytical survey of the polyphenols of seeds of varieties of grape (Vitis vinifera) cultivated in Greece: implications for exploitation as a source of value‐added phytochemicals
Authors: Guendez Ramila , Kallithraka Stamatina , Makris Dimitris P. , Kefalas Panagiotis 
Published: January 2005

AbstractSeed samples from 12 white and 25 red international and Hellenic native grape varieties (Vitis vinifera) were screened for their polyphenolic composition. The polyphenols determined were mainly of low molecular weight, including gallic acid, catechin, epicatechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate and the procyanidins B1 and B2. Average values of total content for white and red varieties (376 and 388 mg/100 g seeds, respectively) were very similar. Comparable results were observed with respect to the individual polyphenol content with seeds from red varieties being, in general, slightly richer. The predominant ﬂavanol monomer in white and red varieties was catechin (which accounted for 50.5 and 49.3%, respectively, of the total content), whilst gallic acid and epigallocatechin were the constituents showing the lowest content, respectively. The data obtained are discussed with regard to the exploitation of grape seeds as a low‐cost source of value‐added phytochemicals. Copyright © 2005 John Wiley & Sons, Ltd.
HPLC quantiﬁcation of uncarine D and the anti‐plasmodial activity of alkaloids from leaves of Mitragyna inermis (Willd.) O. Kuntze
Authors: Fiot Julien , Baghdikian Béatrice , Boyer Laurent , Mahiou Valérie , Azas Nadine , Gasquet Monique , Timon‐David Pierre , Balansard Guy , Ollivier Evelyne 
Published: January 2005

AbstractAn efﬁcient system for the analysis of the total alkaloids extracted from leaves of Mitragyna inermis (Willd.) O. Kuntze (Rubiaceae) by HPLC using a reversed‐phase column is described. The chromatographic conditions allowed the separation of indole and oxindole alkaloids in leaf extracts, and the quantiﬁcation of uncarine D in samples collected in Burkina Faso and Mali. The HPLC method described was validated for its speciﬁcity, linearity and precision using an internal standard (naphthalene). The concentrations of uncarine D in various extracts were compared with their in vitro anti‐plasmodial activity. The anti‐proliferative activity on chloroquine‐resistant strain (W2) of Plasmodium falciparum was not correlated with the concentration of uncarine D in leaves. Copyright © 2005 John Wiley & Sons, Ltd.