bluuebunny/crossref_metadata_2025_split huggingface dataset:
A proposed through‐flow inverse method for the design of mixed‐flow pumps
Authors: Borges João Eduardo 
Published: October 2005

AbstractA through‐flow (hub‐to‐shroud) truly inverse method is proposed and described in this paper. It uses as a initial design specification, an imposition of mean swirl, i.e. radius times mean tangential velocity, given throughout the meridional section of the turbomachine. In the present implementation, it is assumed that the fluid is invsicid, incompressible and irrotational at inlet and the blades are supposed to have zero thickness. Only blade rows that impart to the fluid a constant work along the span will be considered.An application of this procedure to design the rotor of a mixed‐flow pump will be described in detail. The strategy used to find a suitable mean swirl distribution and the other design inputs is also described. The final blade shape and pressure distributions on the blade surface are presented, showing that it is possible to obtain feasible designs using this technique. Another advantage of this technique is the fact that it does not require large amounts of CPU time.
Two‐phase flow modelling in gas‐stirred liquid vessels with SUPG‐stabilized equal‐order interpolations
Authors: Nigro N. , Storti M. , Idelsohn S. 
Published: October 2005

AbstractThe modelling of liquid flow in gas‐stirred vessels is described. A simple two‐phase model accounts for the buoyancy effect of bubbles. Friction between liquid and gas is modelled with the hypothesis of independent bubbles. The resulting PDE system is discretized with an original version of the SUPG‐FEM technique which stabilizes both the convection term and equal‐order interpolations for velocity and pressure, which are known to be unstable for incompressible flows. The resulting steady state discrete system is solved via pseudotemporal explicit iteration with a local time step and a preconditioning to homogenize the temporal scales for liquid and gas.
Simulation of three‐dimensional unsteady viscous free surface flow around a ship model
Authors: Alessandrini B. , Delhommeau G. 
Published: October 2005

AbstractWe present here a numerical method for solving the free surface flow around a ship at forward speed in calm water. The fluid is assumed to be Newtonian and the Reynolds‐averaged Navier‐Stokes equations are solved by a finite difference method. Modelization of turbulence is achieved by the algebraic model proposed by Baldwin and Lomax. Fully non‐linear free surface conditions are satisfied in the model and a method to avoid the incompatibility between free surface conditions and no‐slip conditions at the waterline is proposed. Numerical results obtained for a Wigley hull are compared with experimental results.
A new fully coupled solution of the Navier‐Stokes equations
Authors: Deng G. B. , Piquet J. , Queutey P. , Visonneau M. 
Published: October 2005

AbstractA fully coupled method for the solution of incompressible Navier‐Stokes equations is investigated here. It uses a fully implicit time discretization of momentum equations, the standard linearization of convective terms, a cell‐centred colocated grid approach and a block‐nanodiagonal structure of the matrix of nodal unknowns. The Method is specific in the interpolation used for the flux reconstruction problem, in the basis iterative method for the fully coupled system and in the acceleration means that control the global efficiency of the procedure. The performance of the method is discussed using lid‐driven cavity problems, both for two and three‐dimensional geometries, for steady and unsteady flows.
Prediction of thermal stratification in a curved duct with 3D body‐fitted co‐ordinates
Authors: Ushijima S. 
Published: October 2005

AbstractThis paper concerns a numerical prediction method for buoyancy‐influenced flows using three‐dimensional non‐orthogonal curvilinear co‐ordinates. The numerical analysis of the transformed governing equations for thermal hydraulics is based on a Lagrangian method, in which advected physical values are evaluated by local cubic spline interpolations with third‐order accuracy in the three‐dimensional computational domain. In addition, the buoyancy and diffusion terms are discretized in the Lagrangian scheme so as to have second‐order accuracy with respect to time and space. The Neumann boundary conditions, which have been rather difficult for non‐orthogonal co‐ordinates to deal with, can be implemented by making use of normal vectors on the physical boundary surfaces and cubic spline interpolations. The developed numerical method is applied to the steady isothermal flow in a curved pipe and the unsteady stratified flow in a curved duct. Both of the predicted values are in good agreement with the experimental results and the validity of the prediction method is confirmed.
Fully discrete arbitrary‐order schemes for a model parabolic equation
Authors: Shi J. 
Published: October 2005

AbstractA fully discrete methodology is investigated from which two‐level, explicit, arbitrary‐order, conservative numerical schemes for a model parabolic equation can be derived. To illustrate this, fully discrete three‐, five‐, seven‐ and nine‐point conservative numerical schemes are presented, revealing that a higher‐order scheme has a better stability condition. A method from which high‐order numerical schemes for a scalar advection‐diffusion equation can be developed is discussed. This method is based on high‐order schemes of both the advection and diffusion equations.
A simplified marker and cell method for unsteady flows on non‐staggered grids
Authors: Cheng Liang , Armfield Steven 
Published: October 2005

AbstractThe SMAC (simplified marker and cell) time‐advancing method for solving the unsteady incompressible Navier‐Stokes equations on non‐staggered grids is developed in generalized co‐ordinate systems. The primitive variable formulation uses Cartesian velocities and pressure, all defined at the centre of the control volume, as the dependent variables. A special elliptic flux correction at the faces of the finite volume is utilized in discretizing the continuity equation to suppress pressure oscillations. The test flows considered are a polar cavity flow starting from rest and the flow around a circular cylinder. The numerical results are compared with experimental results and results obtained by the well‐known SIMPLEC and PISO methods. The comparisons show that the elliptic flux correction technique works well in suppressing pressure oscillations and that the SMAC method is more efficient than the SIMPLEC and PISO methods for both steady and unsteady flows.
A numerical modelling study of the flow and salinity structure in the Godavari Estuary, east coast of India
Authors: Rao A. D. 
Published: October 2005

AbstractThe Godavari Estuary in Andhra Pradesh (a state bordering the east coast of India) communicates with the Bay of Bengal. Conditions in the estuary are characterized by a seasonally varying freshwater discharge and an intrusion of salt water from the bay dependent upon the flow associated with the semi‐diurnal component of the astronomical tide. A numerical model is applied to simulate the flow and salinity structures, which in the case of the Godavari Estuary have also been determined observationally and are documented in the literature. Observational data on the flow and salinity structure during two seasons are used in a comparison with theoretical results derived using a turbulent energy equation. Reasonable agreement is obtained between the model results and the observational data; in particular, streamlines are computed for the tidally averaged (or mean) component of the density‐controlled flow.
Mathematical modelling of the coupled reacting boundary layer equations
Authors: Villasenor R. , Chen J. Y. 
Published: October 2005

AbstractA new numerical scheme for reacting axisymmetric jet flows formed between a fuel jet and co‐flowing air has been developed. The model is mathematically described by a set of non‐linear parabolic partial differential equations in two space dimensions, i.e. the boundary layer equations. The numerical scheme that the programme uses for solving the fully coupled conservation equations of mass, momentum, energy and species is a generaliztion of the discretization technique recently developed by Villasenor (J. Math. Comput. Simul., 36, 203–208 (1994)). Chemical production (and destruction) of the species is allowed to occur through N elementary reversible (or irreversible) reactions involving k species, although in the present model the reaction rates are evaluated with a simplified kinetic mechanism for a one‐step global reaction. Thermal radiation is considered assuming an optically thin limit and adopting the grey medium approximation. Allowances are made for natural convection effects and variable thermodynamic and molecular transport properties. The performance of the model in solving the coupled aerodynamic and finite rate chemistry effects is tested by comparing model predictions with experimental data of Mitchell et al. (Combust. Flame, 37, 227–244 (1980)) for a buoyant, laminar, diffusion axisymmetric methane‐air flame.
One‐dimensional, time‐dependent, homogeneous, two‐phase flow in volcanic conduits
Authors: Ramos J. I. 
Published: October 2005

AbstractA one‐dimensional, time‐dependent, isothermal, homogeneous, two‐phase flow model was developed to study magma ascent in volcanic conduits. The physical modeling equations were numerically solved by means of a TVD (total variation diminishing) predictor‐corrector procedure and by means of a predictor‐corrector technique based on the method of characteristics. The results from the transient model were verified with an analytical solution for wave propagation in conduits without friction and gravitational effects. The numerical solutions were also compared with those of a steady‐state, homogeneous, two‐phase model for basaltic and rhyolitic magma ascents in the fissures and circular conduits of Vesuvius and Mt St. Helens. An application of the model to magma decompression in conduits indicates very short times for gas exsolution, fragmentation, and shock wave propagation, implying that the modelling of gas exsolution should involve non‐equilibrium kinetics effects. Future coupling of the transient magma ascent model with magma chamber and pyroclastic dispersion models should allow for more realistic simulations of the time‐dependent behavior of real volcanic eruptions.
Numerical studies on effect of check valve performance on pressure surges during pump trip in pumping systems with air entrainment
Authors: Lee T. S. 
Published: October 2005

AbstractRecent numerical investigations on pressure surges during pump trip in pumping installations showed that by including an air entrainment variable wave speed model, reasonable predictions of transient pressure surges with proper phasing and attenuation of pressure peaks can be obtained. These calculated results are consistent with similar field measurements made with the pumps operating at low pump cut‐out levels, when air entrainment due to an attached surface vortex was observed. However, in the numerical calculation procedures it is assumed that the inertia of the moving elements of the check valve is small and that the check valve closes at zero reverse flow velocity. In practice, check valves seldom close precisely at zero reverse flow velocity. With the check valves not closing at zero reverse velocity, the present numerical computations show that the air content in a fluid system can adversely affect the check valve performance. With the fluid system operating within a critical range of air entrainment values, the present analysis showed that there is a possibility of ‘check valve slamming’ when the check valves are selected based only on the analysis of an air‐free system. This phenomenon is confirmed through field observations.
Atheroma development in apolipoprotein E‐null mice is not regulated by phosphorylation of p27Kip1 on threonine 187
Authors: Sanz‐González Silvia M. , Melero‐Fernández de Mera Raquel , Malek Nisar P. , Andrés Vicente 
Published: October 2005

AbstractExcessive cellular proliferation is thought to contribute to neointimal lesion development during atherosclerosis and restenosis after angioplasty. Inhibition of cyclin‐dependent kinase (CDK) activity by p27 inhibits mammalian cell growth. Mounting evidence indicates that p27 negatively regulates neointimal thickening in animal models of restenosis and atherosclerosis, and its expression in human neointimal lesions is consistent with such a protective role. Cell cycle progression is facilitated by cyclinE/CDK2‐dependent phosphorylation of p27 on threonine 187 (T187) during late G1. The purpose of this study was to assess whether this phosphorylation event plays a role during atherosclerosis. To this end, we generated apolipoprotein E‐null mice with both p27 alleles replaced by a mutated form non‐phosphorylatable at T187 (apoE−/−p27T187A mice) and investigated the kinetics of atheroma development in these animals compared to apoE−/− controls with an intact p27 gene. Fat feeding resulted in comparable level of hypercholesterolemia in both groups of mice. Surprisingly, aortic p27 expression was not increased in fat‐fed apoE−/−p27T187A mice compared with apoE−/− controls. Moreover, atheroma size, lesion cellularity, proliferation, and apoptotic rates were undistinguishable in both groups of fat‐fed mice. Thus, in contrast to previous studies that highlight the importance of p27 phosphorylation at T187 on the control of p27 expression and function in different tissues and pathophysiological scenarios, our findings demonstrate that this phosphorylation event is not implicated in the control of aortic p27 expression and atheroma progression in hypercholesterolemic mice. J. Cell. Biochem. 97: 735–743, 2006. © 2005 Wiley‐Liss, Inc.
Expansion of mesenchymal stem cells isolated from pediatric and adult donor bone marrow
Authors: Mareschi Katia , Ferrero Ivana , Rustichelli Deborah , Aschero Simona , Gammaitoni Loretta , Aglietta Massimo , Madon Enrico , Fagioli Franca 
Published: October 2005

AbstractThe enormous plasticity of mesenchymal stem cells (MSCs) suggests an improvement of a standard protocol of isolation and ex vivo expansion for experimental and clinical use. We isolated and expanded MSCs from bone marrow (BM) of pediatric and young adult donors, to analyze the growth kinetic, immunophenotype, telomere length, karyotype during ex vivo expansion. Seventeen BM samples were collected from young adult donors and 8 from pediatric donors. MSCs isolated from two groups showed no morphological differences while their cell growth was strictly related to the donor's age. The MSCs isolated from pediatric donors reached a cumulative PD almost twice as high as MSCs isolated from young adult donors after 112 days (10.2 ± 1.9 versus 5.5 ± 3.7). Furthermore, we analyzed the modulation of antigen expression in the MSCs isolated from two groups until 10th passage (77 days) and there was no significant difference between the modulation of antigen expression. In particular, at the first passage, MSCs showed a low contamination of hemopoietic cells which became insignificant in the following passages. There was a high expression of CD90, CD29, CD44 and CD105 and variable and moderate expression of CD166 and CD106 at the start of MSC culture and at each passage during expansion. No chromosomal alteration or evidence of cellular senescence were observed in all analyzed samples. All these data suggest that MSCs can be isolated and expanded from most healthy donors, providing for an autologous source of stem cells. J. Cell. Biochem. 97: 744–754, 2006. © 2005 Wiley‐Liss, Inc.
Differentiation‐specific transcriptional regulation of the ESE‐2 gene by a novel keratinocyte‐restricted factor
Authors: Tummala Ramakumar , Sinha Satrajit 
Published: October 2005

AbstractEpithelium specific Ets‐2 (ESE‐2), an epithelium‐specific ETS‐domain transcription factor, is highly expressed in differentiated keratinocytes. To understand the molecular mechanisms that govern the cell‐type and differentiation‐specific expression of ESE‐2 in keratinocytes, we have focused our studies on the identification and characterization of its cis‐regulatory elements. We first performed DNase I hypersensitive site mapping and demonstrated that the promoter region of ESE‐2 is in open chromatin conformation in differentiated keratinocytes. Next, we performed transient transfection assays with several 5′ serially deleted constructs containing segments of the ESE‐2 promoter. These experiments have led to the identification of a short fragment that shows remarkable sequence conservation between several species and harbors most of the transcriptional activity. Interestingly, a high level of transcriptional activity was only observed when the transfected keratinocytes were induced to differentiate by increasing the calcium concentration in the cell‐culture medium. To identify the factors that mediate the transcriptional activity, we analyzed this segment by mutational and electrophoretic mobility shift assays (EMSA) experiments. Our studies have identified a critical stretch of nucleotides that is important for both basal as well as calcium responsive reporter activity and that binds to a nuclear factor, keratinocyte restricted factor (KRF). KRF is a novel transcription factor that is restricted to nuclear extracts isolated from keratinocytes and that binds to unique DNA sequences, which do not resemble any known consensus binding motif for transcription factors. Our preliminary experiments shed light on the biochemical nature of KRF and set the stage for future studies in identification of KRF and testing its role in governing ESE‐2 gene expression in vivo. J. Cell. Biochem. 97: 766–781, 2006. © 2005 Wiley‐Liss, Inc.
Micro‐Raman spectroscopy used to identify and grade human skin pilomatrixoma
Authors: Cheng Wen‐Ting , Liu Ming‐Tzen , Liu Han‐Nan , Lin Shan‐Yang 
Published: October 2005

AbstractRaman microspectroscopy was applied to analyze the changes in structural conformation and chemical composition of the mass of human skin pilomatrixoma (PMX). The normal skin dermis, collagen type I, and hydroxyapatite (HA) were used as control. The excised specimens from two patients diagnosed as a typical PMX were detected, in which one specimen was a soft mass, but the other was a hard mass with somewhat calcified deposits via histopathological examination. The Raman spectrum of normal skin dermis was found to be similar to the Raman spectrum of collagen type I, confirming that the collagen type I was a predominant component in normal skin dermis. The differences of Raman peak intensity between normal skin dermis and soft or hard PMX mass were obvious at 1,622–1,558, 1,400–1,230, 1,128, 1,000–850, 749, and 509 cm−1. In particular, the peak at 1,665 cm−1 assigned to amide I band shifted to 1,655 cm−1 and the peak at 1,246 cm−1 corresponding to amide III band was reduced in its intensity in hard PMX mass. The significant changes in collagen content and its structural conformation, the higher content of tryptophan, and disulfide formation in PMX masses were markedly evidenced. In addition, the shoulder and weak peak at 960 cm−1 assigned to the stretching vibration of PO of HA also appeared respectively in the Raman spectra of soft and hard PMX masses, suggesting the occurrence of calcification of HA in the PMX tissue, particularly in the hard PMX mass. The result indicates that the micro‐Raman spectroscopy may provide a highly sensitive and specific method for identifying normal skin dermis and how it differs in chemical composition from different PMX tissues. Microsc. Res. Tech. 68:75–79, 2005. © 2005 Wiley‐Liss, Inc.
Immobilization of DNA on 11‐mercaptoundecanoic acid‐modified gold (111) surface for atomic force microscopy imaging
Authors: Song Yonghai , Li Zhuang , Liu Zhiguo , Wei Gang , Wang Li , Sun Lanlan 
Published: October 2005

AbstractImmobilized DNA on preformed 11‐mercaptoundecanoic acids (MUDA) self‐assembled monolayers (SAMs) on a gold (111) surface was bound by a divalent cation bridges was imaged by atomic force microscopy (AFM). The DNA immobilization was attributed to the formation of ionic bridges between the carboxylate groups of MUDA and the phosphate groups of DNA. AFM images revealed that DNA molecules could be immobilized strongly enough to permit stable and reproducible imaging. The effect of different bridge cations, such as Mg2+, Zn2+ and Cu2+, and the pH of DNA assembled solution on immobilization and conformation of DNA was studied. Plasmid DNA pBR 322/Pst I molecules were straightened by using a molecular combing technique on the MUDA surface. Microsc. Res. Tech. 68:59–64, 2005. © 2005 Wiley‐Liss, Inc.
Chlorhexidine‐induced ultrastructural alterations in oral biofilm
Authors: Vitkov L. , Hermann A. , Krautgartner W.D. , Herrmann M. , Fuchs K. , Klappacher M. , Hannig M. 
Published: October 2005

AbstractChlorhexidine, the most used biocide in periodontology, alters the permeability of the bacterial cell membrane. However, the chlorhexidine‐induced morphological alterations in the oral biofilm have not been studied. To examine the effects of chlorhexidine on oral biofilm on an electron microscopic level, gingival epithelial cells with attached biofilm were collected from 10 volunteers, subjected to 0.1% chlorhexidine for 1 or 5 min, stained with ruthenium red‐tetroxide, and analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM visualized the bacterial glycocalyces and the biofilm matrix on the biofilm surface; however, no chlorhexidine‐induced alterations were observed. TEM revealed loss of bacterial membrane integrity and fimbrial disintegration in a few bacteria. In the proximity of these alterations, a restricted matrix disintegration was also observed. However, the chlorhexidine‐induced alterations only effected a minor part of the oral biofilm and did not cause its disintegration. These findings suggest the insufficient efficiency of chlorhexidine against oral biofilm. Microsc. Res. Tech. 68:85–89, 2005. © 2005 Wiley‐Liss, Inc.
Natriuretic peptide expression in the heart of the TTR‐ANP transgenic mouse—Comparison to the normal heart
Authors: Lundberg Simon , Hansson Magnus 
Published: October 2005

AbstractThe transgenic mice, TTR‐ANP, carrying a fusion gene comprising the transthyretin promoter and the atrial natriuretic peptide (ANP) structural sequence, are known to have elevated ANP plasma levels as well as lowered blood pressure levels. On the other hand, it is not known whether these transgenic mice show changed natriuretic peptide (NP) expression patterns in the heart. Therefore, we examined the distribution of NPs in the myocardium and the conduction system of transgenic mice overexpressing ANP, as well as in wild‐type littermates. The hearts were serially sectioned and processed for immunohistochemistry, with antisera against ANP and brain natriuretic peptide (BNP). Florescence microscopy was performed for qualitative analysis. Immunoreactivity for ANP and BNP was detected to a similar degree in the conduction system of both transgenic and wild‐type mice. The nodal tissues never exhibited immunoreactions for ANP or BNP, whereas Purkinje fibers of the atrioventricular junctional tissue, bundle branches, and the peripheral Purkinje fiber network exhibited specific immunoreactivity. Atrial and ventricular myocytes of both transgenic and wild‐type mice exhibited ANP and BNP to a similar extent. This is the first study examining the expression pattern of NPs in the cardiac conduction system of the mouse as well as the pattern of ANP and BNP expression in the conduction system of TTR‐ANP transgenic mice and its wild‐type siblings. The findings in this study suggest that ectopic ANP expression and release do not repress cardiac production of ANP. Microsc. Res. Tech. 68:97–106, 2005. © 2005 Wiley‐Liss, Inc.