bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical investigation of combustion characteristics in ram‐jet dump combustor with side‐inlet
Authors: Chuang Shu‐Hao , Lin Hsun‐Cheng , Chen Ming‐Hua , Jan Jin‐Fa
Published: November 2005

The combustion flow of a sudden‐expansioin dump combustor with injecting side‐inlet is analysed using the SIMPLE‐C algorithm and the Jones‐Launder k‐ϵ two‐equation turbulence model. The transport properties of velocity, turbulence kinetic energy, temperature and combustion efficiency as a function of the injected mass fraction and the number of side‐inlet nozzles are solved in this paper. The axial velocities of the sudden‐expansion dump combustor without injected side‐inlet flow are solved first and found to be in good agreement with the experimental data of Moon and Rudinger. For a fixed value of the side‐inlet number the wall temperature and combustion efficiency of the dump combustor are decreased when the injected mass fraction is increased. For a fixed value of the injected mass fraction the wall temperature and combustion efficiency are decreased when the number of side‐inlet nozzles is increased.
An orthogonal mapping technique for the computation of a viscous free‐surface flow
Authors: Cliffe K. A. , Tavener S. J. , Wheeler A. A.
Published: November 2005

In this paper we describe finite element computations of the free‐surface flow of a viscous fluid down an undulating inclined plane. The technique developed here employs an orthogonal mapping that is computed along with the velocity and pressure. This is allied to a technique to compute symbolically the Jacobian and other derivatives required for numerical continuation methods. The solutions obtained are compared with laboratory experiments and finite element computations reported by Pritchard and co‐workers. The finite element computational method used by these authors employs spines to represent the free surface. An excellent agreement is shown to exist between the new computations and the laboratory experiments, and with the numerical solutions of Pritchard and co‐workers.
Multigrid solution of the Navier–Stokes equations on highly stretched grids
Authors: Sockol Peter M.
Published: November 2005

Relaxation‐based multigrid solvers for the steady incompressible Navier–Stokes equations are examined to determine their computational speed and robustness. Four relaxation methods were used as smoothers in a common tailored multigrid procedure. The resulting solvers were applied to three two‐dimensional flow problems, over a range of Reynolds numbers, on both uniform and highly stretched grids. In all cases the L2 norm of the velocity changes is reduced to 10−6 in a few 10's of fine‐grid sweeps. The results of the study are used to draw conciusions on the strengths and weaknesses of the individual relaxation methods as well as those of the overall multigrid procedure when used as a solver on highly stretched grids.
On the instability of a full non‐parallel flow—Kovasznay flow
Authors: Chen H. B.
Published: November 2005

The local instability of a full non‐parallel flow is investigated. The basic flow is a horizontal uniform flow about a vertical array of periodic bound eddies. This flow was found by Kovasznay as an exact solution to the Navier–Stokes equations. The problem is formulated as an initial value problem with two sets of complete orthogonal functions. A new approach to the problem with semi‐infinite domain is given computationally with a new modified rational Chebyshev function. The linear stability analysis of the Kovasznay flow is performed with respect to the odd–rational Chebyshev mode and the even–rational Chebyshev mode for the evolution of disturbances. While symmetrical vortex sheets appeared through the process of big eddies breaking into small eddies in the odd–rational Chebyshev mode, the von Kármán vortex street phenomena is found in the even–rational Chebyshev mode. The mode corresponding to antisymmetric velocity perturbation is found to be far more unstable than symmetric disturbance. An organized structure is developed after the onset of instability. Several general characteristics of non‐parallel flow stability are discussed.
Numerical modelling and computation of fluid pressure transients with air entrainment in pumping installations
Authors: Lee T. S.
Published: November 2005

In pumping installations such as sewage pumping stations, where gas content and air entrainment exist, the computation of fluid pressure transients in pipelines becomes grossly inaccurate when a constant wave speed is assumed. An accurate numerical model with gas release and absorption has been developed in this paper and used to compute the fluid pressure transients in the pumping mains of selected pumping installations. Free and dissolved gases in the transported fluid and cavitation at vapour pressure are also modelled. When compared with the gas‐free case, computations show that entrained, entrapped or released gases amplify the positive pressure peak, increase surge damping and produce asymmetric pressure surges. While the upsurge with air entrainment in the pipelines was considerably amplified, the downsurge was only marginally reduced. The computed results show good agreement with the data available.
Simulation of impacts of fluid free surfaces with solid boundaries
Authors: Johnson David B. , Raad Peter E. , Chen Shea
Published: November 2005

Deficiencies associated with the simulation of impacts of fluid free surfaces with solid boundaries by use of marker‐and‐cell methods are identified and addressed. New procedures are introduced that affect the movement of markers in cells adjacent to a solid boundary, the flags of the cells that comprise a solid boundary and the pressure boundary condition for a cell in which impact occurs. Combined with fundamental changes in the sequence of steps in the computational cycle, these new procedures allow the intentional treatment of impact. As a result, improved estimates are obtained of the pressure associated with the cells adjacent to a boundary along which impact occurs. Consequently, more appropriate adjustments are made of the tentative internal velocities associated with such cells. In addition, a special procedure is presented for the adjustment of the tentative internal velocity between two surface cells. Finally, a new cell type termed a corner cell is defined and a procedure for its treatment is presented. Numerical examples are included to illustrate the previous deficiencies associated with the simulation of impact as well as the effectiveness of the new methods presented in this paper. Validation of the new methods is achieved by comparison with experimental results for spillage over a containment dike.
Dynamic vorticity condition: Theoretical analysis and numerical implementation
Authors: Wu Jie‐Zhi , Wu Xiao‐Hui , Ma Hui‐Yang , Wu Jain‐Ming
Published: November 2005

The dynamic boundary conditions for vorticity, derived from the incompressible Navier‐Stokes equations, are examined from both theoretical and computational points of view. It is found that these conditions can be either local (Neumann type) or global (Dirichlet type), both containing coupling with the boundary pressure, which is the main difficulty in applying vorticity‐based methods. An integral formulation is presented to analyse the structure of vorticity and pressure solutions, especially the strength of the coupling. We find that for high‐Reynolds‐number flows the coupling is weak and, if necessary, can be effectively bypassed by simple iteration. In fact, even a fully decoupled approximation is well applicable for most Reynolds numbers of practical interest. The fractional step method turns out to be especially appropriate for implementing the decoupled approximation. Both integral and finite difference methods are tested for some simple cases with known exact solutions. In the integral approach smoothed heat kernels are used to increase the accuracy of numerical quadrature. For the more complicated problem of impulsively started flow over a circular cylinder at Re = 9500 the finite difference method is used. The results are compared against numerical solutions and fine experiments with good agreement. These numerical experiments confirm our thoeretical analysis and show the advantages of the dynamic condition in computing high‐Reynolds‐number flows.
Pressure‐based method for combustion instability analysis
Authors: Kim Y. M. , Chen Z. J. , Chen C. P. , Ziebarth J. P.
Published: November 2005

An improved pressure‐based method has been applied to predict the two‐dimensional instability analysis of liquid‐fuelled rocket engines. This method is non‐iterative for transient flow calculations and applicable to all‐speed flows. Validation cases include the shock‐tube problem, the blast flow field and unsteady spraycombusting flows. Computations for the combustion instability analysis were carried out for various combustion parameters such as spray initial conditions and combustor geometries. Unsteady behaviours of the stable and unstable spray flame fields and effects of acoustic oscillations on the fuel droplet vaporization and combustion process are studied in detail. The present numerical model successfully demonstrates the capability of predicting combustion instability as well as fast transient compressible flows at all speeds.
Efficient higher‐order backward characteristics schemes for transient advection
Authors: Yu T. S. , Li C. W.
Published: November 2005

The use of the highest‐order ((N – 1)th‐order) Lagrangian interpolation Polynomial for the approximation of the exact solution in the backward characteristics scheme with N nodes is inefficient owing to the excessive number of terms in the polynomial. New schemes based on a combination of lower‐order polynomials to approximate the exact solution are developed, with the relative weighting of the polynomials determined by Fourier mode analysis. With the addition of a flux limiter and a modified discriminator, the resulting schemes are oscillation‐free, highly accurate, efficient and more cost‐effective as compared with those schemes using the highest‐order Lagrangian polynomial.
Decay of confined, two‐dimensional, spatially periodic arrays of vortices: A numerical investigation
Authors: Valentine Daniel T.
Published: November 2005

The disarrangement of a perturbed lattice of vortices was studied numerically. The basic state is an exponentially decaying, exact solution of the Navier‐Stokes equations. Square arrays of vortices with even numbers of vortex cells along each side were perturbed and their evolution was investigated. Whether the energy in the perturbation grows somewhat before it decays or decays monotonically depends on the initial strength of the vortices of the basic state, the extent of lateral confinement and the structure of the perturbation. The critical condition for temporally local instability, i.e. the critical amplitude of the basic state that must be exceeded to allow energy transfer from the basic state to the perturbation, is discussed. In the strongly confined case of a square lattice of four vortices the appearance of enchancement of global rotation is the result of energy transfer from the basic state to a temporally local unstable mode. Energy is transferred from the basic state to larger‐scaled structures (inverse cascade) only if the scales of the larger structures are inherently contained in the initial structure of the perturbation. The initial structure of the double array of vortices is not maintained except for a very special form of perturbation. The facts that large scales decay more slowly than small scales and that, when non‐linearities are sufficiently strong, energy is transferred from one scale to another explain the differences in the disarrangement process for different initial strengths of the vortices of the basic state. The stronger vortices, i.e. the vortices perturbed in a manner that increases their strength, tend to dominate the weaker vortices. The pairing and subsequent merging (or capture) of vortices of like sense into larger‐scale vortices are described in terms of peaks in the evolution of the square root of the palinstrophy divided by the enstrophy.
Accurate computation of convective transport in transient two‐phase flow
Authors: Andrews M. J.
Published: November 2005

The Van Leer method for the computation of convective fluxes is extended to two‐phase flow. By preventing spurious undershoots and overshoots, the scheme preserves physical realism while maintaining high‐order accuracy. This is particulary important for two‐phase flows, since phase exchange terms are typically a function of volume fraction products and numerical diffusion can incorrectly mix the two phases. The scheme described here is constructed to guarantee that the sum of the volume fractions is always unity and that the volume fractions are always greater than or equal to zero. Various test problems are computed to demonstrate the accuracy of the method and to show how the scheme might be incorporated in existing computational methods. In addition to multiphase flow applications, setting equal phase velocities results in a volume marker scheme that is well suited to single‐phase interface tracking problems.
Computation of backward‐facing step flows by a second‐order Reynolds stress closure model
Authors: Hwang Robert R. , Peng Y. F.
Published: November 2005

This paper scrutinizes the predictive ability of the differential stress equation model in complex shear flows. Two backward‐facing step flows with different expansion ratios are solved by the LRR turbulence model with an anisotropic dissipation model and the near‐wall regions of the separated side resolved by a near‐wall model. The computer code developed for solving the transport equations is based on the finite‐volume‐finite‐difference method. In the numerical solution of the time‐averaged momenum equations the Reynolds stresses are treated partially as a diffusion term and partially as a source term to avoid numerical instability. Computational results are compared with experimental data. It is found that the near‐wall region of the separated side resolved by the near‐wall model, the LRR model with a simple modification of an anisotropic dissipation model can predict backward step flows well.
Numerical study of a piston‐driven unsteady flow in a pipe with sudden expansion
Authors: Ströll H. , Durst F. , Perić M. , Scheuerer G.
Published: November 2005

This paper presents results of the numerical study of a piston‐driven unsteady flow in a pipe with sudden expansion. The piston closes the larger‐diameter pipe and moves between two limiting positions with strong acceleration or deceleration at the beginning and end of each stroke and constant velocity in between. The piston velocity in the exhaust stroke is about four times higher than in the intake stroke. Periodic piston movement in this fashion creates a complex unsteady flow between the piston head and the plane of sudden expansion. The numerical method is implicit and of finite volume type, using a moving grid and a collocated arrangement of variables. Second‐order spatial discretization, fine grids and a multigrid solution method were used to ensure high accuracy and good efficiency. Spatial and temporal discretization errors were of the order of 1% and 0.1% respectively. The features of the flow are discussed and the velocity profiles are compared with experimental data, showing good qualitative and quantitative agreement.
On Taylor weak statement finite element methods for computational fluid dynamics
Authors: Chaffin D. J. , Baker A. J.
Published: November 2005

A Taylor series augmentation of a weak statement (a ‘Taylor weak statement’ or ‘Taylor‐Galerkin’ method) is used to systematically reduce the dispersion error in a finite element approximation of the one‐dimensional transient advection equation. A frequency analysis is applied to determine the phase velocity of semi‐implicit linear, quadratic and cubic basis one‐dimensional finite element methods and of several comparative finite difference/finite volume algorithms. The finite element methods analysed include both Galerkin and Taylor weak statements. The frequency analysis is used to obtain an improved linear basis Taylor weak statement finite element algorithm. Solutions are reported for verification problems in one and two dimensions and are compared with finite volume solutions. The improved finite element algorithms have sufficient phase accuracy to achieve highly accurate linear transient solutions with little or no artificial diffusion.
Numerical analysis of finite amplitude motion of waves and a moored floating body under severe storm conditions
Authors: Takikawa Kiyoshi , Yamada Fumihiko , Sato Keiji , Furuta Hideki
Published: November 2005

The motion of a moored floating body under the action of wave forces, which is influenced by fluid forces, shape of the floating body and mooring forces, should be analysed as a complex coupled motion system. Especially under severe storm conditions or resonant motion of the floating body it is necessary to consider finite amplitude motions of the waves, the floating body and the mooring lines as well as non‐linear interactions of these finite amplitude motions.

The problem of a floating body has been studied on the basis of linear wave theory by many researchers. However, the finite amplitude motion under a correlated motion system has rarely been taken into account.

This paper presents a numerical method for calculating the finite amplitude motion when a floating body is moored by non‐linear mooring lines such as chains and cables under severe storm conditions.
A higher‐order boundary element method for three‐dimensional potential problems
Authors: Yuelong Zang , Yumin Cheng , Wu Zhang
Published: November 2005

A method of eliminating the singularities involved in boundary element methods for three‐dimensional potential problems is presented and the non‐singular expressions of integrals on an element on which the singular point is situated are given for linear and quadratic interpolation functions. Numerical examples are compared with analytical solutions to show that the higher‐order interpolations have better precision.
Numerical analysis of fluid flow and mass transfer in a channel with a porous bottom wall
Authors: Yucel Nuri , Turkoglu Hasmet
Published: November 2005

The flow of a solution between parallel plates is considered. The bottom plate is porous, while the top one is an impermeable solid. A computer program based on the control volume approach was developed to analyse the flow and concentration fields. The effects of the slip at the porous wall on the velocity and particle concentration distributions were investigated. It was observed that as the slip increases, the concentration on the porous wall decreases and the maximum velocity moves towards the porous wall. The concentration on the porous wall increases in the flow direction. This increase in the particle concentration along the porous wall may cause a reduction of the porosity and hence a variation in the suction rate along the porous wall. In order to take this effect into account, a linearly varying transverse velocity along the porous wall was considered. The results were compared with the data available in the literature.
Transient solutions for three‐dimensional lid‐driven cavity flows by a least‐squares finite element method
Authors: Tang Li Q. , Cheng Tiwu , Tsang Tate T. H.
Published: November 2005

A time‐accurate least‐squares finite element method is used to simulate three‐dimensional flows in a cubic cavity with a uniform moving top. The time‐ accurate solutions are obtained by the Crank‐Nicolson method for time integration and Newton linearization for the convective terms with extensive linearization steps. A matrix‐free algorithm of the Jacobi conjugate gradient method is used to solve the symmetric, positive definite linear system of equations. To show that the least‐squares finite element method with the Jacobi conjugate gradient technique has promising potential to provide implicit, fully coupled and time‐accurate solutions to large‐scale three‐dimensional fluid flows, we present results for three‐dimensional lid‐driven flows in a cubic cavity for Reynolds numbers up to 3200.
The use of a reformulation of the hydrostatic approximation Navier‐Stokes equations for geophysical fluid problems
Authors: Zuur E. A. H.
Published: November 2005

In order to simulate geophysical general circulation processes, to simplify the governing equations of motion, often the vertical momentum equation of the Navier‐Stokes equations is replaced by the hydrostatic approximation equation. The resulting equations are reformulated and a variational formulation of the linearized problem is derived. Iteration schemes are presented to solve this problem. A finite element method is discussed, as well as a finite difference method which is based on a grid that is often used in geophysical general circulation models. The schemes are extended to the non‐linear case. Numerical examples are presented to demonstrate the performance of the derived iteration schemes.
Functional demonstration of surface carbonic anhydrase IV activity on rat astrocytes
Authors: Svichar Nataliya , Esquenazi Susana , Waheed Abdul , Sly William S. , Chesler Mitchell
Published: November 2005

Buffering of the brain extracellular fluid is catalyzed by carbonic anhydrase (CA) activity. Whereas the extracellular isoform CA XIV has been localized exclusively to neurons in the brain, and to glial cells in the retina, there has been uncertainty regarding the form or forms of CA on the surface of brain astrocytes. We addressed this issue using physiological methods on cultured and acutely dissociated rat astrocytes. Prior work showed that the intracellular lactate‐induced acidification (LIA) of astrocytes is diminished by benzolamide, a poorly permeant, nonspecific CA inhibitor. We demonstrate that pretreatment of astrocytes with phosphatidylinositol‐specific phospholipase C (PI‐PLC) results in a similar inhibition of the mean LIA (by 66 ± 3%), suggesting that the glycosylphosphatidylinositol‐anchored CA IV was responsible. Pretreatment of astrocytes with CA IV inhibitory antisera also markedly reduced the mean LIA in both cultured cortical (by 46 ± 4%) and acutely dissociated hippocampal astrocytes (by 54 ± 8%). Pre‐immune sera had no effect. The inhibition produced by PIPLC or CA IV antisera was not significantly less than that by benzolamide, suggesting that the majority of detectable surface CA activity was attributable to CA IV. Thus, our data collectively document the presence of CAIV on the surface of brain astrocytes, and suggest that this is the predominant CA isoform on these cells. © 2005 Wiley‐Liss, Inc.
Tandem‐pore domain potassium channels are functionally expressed in retinal (Müller) glial cells
Authors: Skatchkov S.N. , Eaton M.J. , Shuba Y.M. , Kucheryavykh Y.V. , Derst C. , Veh R.W. , Wurm A. , Iandiev I. , Pannicke T. , Bringmann A. , Reichenbach A.
Published: November 2005

Tandem‐pore domain (2P‐domain) K+‐channels regulate neuronal excitability, but their function in glia, particularly, in retinal glial cells, is unclear. We have previously demonstrated the immunocytochemical localization of the 2P‐domain K+ channels TASK‐1 and TASK‐2 in retinal Müller glial cells of amphibians. The purpose of the present study was to determine whether these channels were functional, by employing whole‐cell recording from frog and mammalian (guinea pig, rat and mouse) Müller cells and confocal microscopy to monitor swelling in rat Müller cells. TASK‐like immunolabel was localized in these cells. The currents mediated by 2P‐domain channels were studied in isolation after blocking Kir, KA, KD, and BK channels. The remaining cell conductance was mostly outward and was depressed by acid pH, bupivacaine, methanandamide, quinine, and clofilium, and activated by alkaline pH in a manner consistent with that described for TASK channels. Arachidonic acid (an activator of TREK channels) had no effect on this conductance. Blockade of the conductance with bupivacaine depolarized the Müller cell membrane potential by about 50%. In slices of the rat retina, adenosine inhibited osmotic glial cell swelling via activation of A1 receptors and subsequent opening of 2P‐domain K+ channels. The swelling was strongly increased by clofilium and quinine (inhibitors of 2P‐domain K+ channels). These data suggest that 2P‐domain K+ channels are involved in homeostasis of glial cell volume, in activity‐dependent spatial K+ buffering and may play a role in maintenance of a hyperpolarized membrane potential especially in conditions where Kir channels are blocked or downregulated. © 2005 Wiley‐Liss, Inc.
Lipopolysaccharide‐activated SHP‐1‐deficient motheaten microglia release increased nitric oxide, TNF‐α, and IL‐1β
Authors: Zhao Jie , Brooks Diane M. , Lurie Diana I.
Published: November 2005

Accumulating evidence suggests a deleterious role for activated microglia in facilitating neuronal death by producing neurocytotoxic substances during injury, infection, or neurodegenerative diseases. After cochlear ablation, abnormal microglial activation accompanied by increased neuronal loss within the auditory brainstem occurs in motheaten (me/me) mice deficient in the protein tyrosine phosphatase SHP‐1. To determine whether abnormally activated microglia contribute to neuronal death inme/memice, primary microglial cultures fromme/meand wild‐type mouse cortices were stimulated by the bacterial endotoxin lipopolysaccharide (LPS) to evaluate the secretion of the neurotoxic mediators nitric oxide (NO), tumor necrosis factor‐α (TNF‐α), and interleukin‐1β (IL‐1β).Me/memicroglia release significantly greater amounts of all three mediators compared with wild‐type microglia. However, the increased release of these compounds in microglia lacking SHP‐1 does not appear to occur through activation of extracellular signal‐regulated kinase (ERK), p38 kinase subgroups of mitogen‐activated protein (MAP) kinases, or increases in NF‐κB‐inducing kinase (NIK). These results suggest that abnormal microglial activation and release of neurotoxic compounds may potentiate neuronal death in deafferented cells and can thus potentiate neurodegeneration in theme/mebrainstem. Our data also indicate that SHP‐1 is engaged in signaling pathways in LPS‐activated microglia, but not through regulation of the ERK and p38 MAP kinases. © 2005 Wiley‐Liss, Inc.
Cervicofacial and cervicothoracic rotation flaps in head and neck reconstruction
Authors: Moore Brian A. , Wine Todd , Netterville James L.
Published: November 2005

Background.

Compound cervicofacial and cervicothoracic rotation flaps are highly versatile flaps that may be applied to a variety of defects of the cheek, orbit, periauricular region, and neck. These rotation advancement flaps should be a staple of the head and neck surgeon's reconstructive armamentarium.

Methods.

This is a retrospective review of medical records at a university‐based head and neck cancer center.

Results.

Thirty‐three patients were identified, with a mean age of 66 years. Primary or recurrent skin neoplasms made up the most common indication for surgery, followed by primary parotid tumors and cervical lymphatic metastases from upper aerodigestive tract malignancies. Defects of the cheek, orbit, periauricular region, and neck were reconstructed with cervicofacial or cervicothoracic flaps, with larger wounds requiring variable extension of the incision onto the chest wall. Other reconstructive modalities were used in 18 cases to increase tissue bulk or provide internal lining. Minor wound complications occurred in 13 patients. There was no statistically significant association between wound complications and smoking or previous radiation therapy.

Conclusions.

Compound cervicofacial and cervicothoracic rotation flaps provide a straightforward, reliable, and efficient means to reconstruct complex defects of the face, lateral skull base, and neck, with the potential for excellent cosmetic results. © 2005 Wiley Periodicals, Inc. Head Neck 27: XXX–XXX, 2005
Unexpected rapid progression of metastatic adenoid cystic carcinoma during treatment with imatinib mesylate
Authors: Lin Ching‐Hung , Yen Roh‐Fan , Jeng Yung‐Ming , Tzen Chin‐Yuan , Hsu Chiun , Hong Ruey‐Long
Published: November 2005

Background.

There is a lack of effective treatment for metastatic adenoid cystic carcinoma (ACC), a usually indolent tumor. We studied the efficacy of imatinib mesylate, a potent inhibitor of KIT tyrosine kinase, in patients with KIT‐positive metastatic ACC.

Methods.

Five patients with lung metastasis were treated in a pilot study with imatinib 400 mg by mouth twice a day. Mutations of c‐kit and platelet‐derived growth factor receptor (PDGFR)‐α in tumors from these patients were analyzed.

Results.

Disease progression was noted in three of five patients during the short treatment periods, ranging from 2 to 3 weeks. Three patients died of disease within 6 months. No detectable mutations were found in c‐kit and PDGFR‐α.

Conclusion.

We observed an unexpected high progression rate of metastatic ACC within short periods during imatinib treatment. Use of imatinib to treat cancers without c‐kit or PDGFR‐α mutation should be approached with caution. © 2005 Wiley Periodicals, Inc. Head Neck 27: XXX–XXX, 2005
25‐year experience of using a linear stapler in laryngectomy
Authors: Bedrin Lev , Ginsburg Genadi , Horowitz Zeev , Talmi Yoav P.
Published: November 2005

Background.

Stapler application for pharyngeal closure after total laryngectomy allows for rapid watertight closure without field contamination and for potentially reduced fistula rate.

Methods.

One thousand four hundred fifteen patients underwent laryngectomy with linear stapler closure. In 98.6%, laryngectomy was performed after radiation failure.

Results.

A relatively high incidence of pharyngeal fistulae (12%) was seen, although these rates were reduced to 5.5% during the recent decade. Simultaneous creation of tracheoesophageal fistula and myotomy by a novel technique was introduced. Swallowing problems were observed in 11 patients and local recurrences in nine patients (0.6%).

Conclusion.

The advantages of mechanical sutures with the closed stapling technique are simple and rapid application, watertight closure with good hemostasis, prevention of field contamination, good speech and deglutition, no increase in fistula rate, and low local recurrence rates. Operating room expenses may also be significantly reduced, rendering this method cost‐effective as well. © 2005 Wiley Periodicals, Inc. Head Neck 27: XXX–XXX, 2005
Synthesis, characterization, and osteocompatibility evaluation of novel alanine‐based polyphosphazenes
Authors: Nair Lakshmi S. , Lee Duron A. , Bender Jared D. , Barrett Eric W. , E.Greish Yaser , Brown Paul W. , Allcock Harry R. , Laurencin Cato T.
Published: November 2005

This study deals with the synthesis and in vitro osteocompatibility evaluation of two novel alanine‐containing biodegradable ester polyphosphazenes as candidates to form self‐setting composites with hydroxyapatite (HAp) precursors. The two novel biodegradable polyphosphazenes synthesized were poly[(ethyl alanato)1.0(ethyl oxybenzoate)1.0 phosphazene] (PN‐EA/EOB) and poly[(ethyl alanato)1.0(propyl oxybenzoate)1.0 phosphazene] (PN‐EA/POB). The polymers were characterized by multinuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). Biodegradability and percentage water absorption of the polymers were evaluated by following the mass change in phosphate buffer (pH 7.4) at 37°C. PN‐EA/POB underwent faster degradation and showed higher water absorption compared to PN‐EA/EOB. Both polymers became insoluble in common organic solvents following hydrolysis presumably due to crosslinking reactions accompanying the degradation process. Osteoblast cell adhesion and proliferation on PN‐EA/EOB and PN‐EA/POB was followed by scanning electron microscopy (SEM) and by using a biochemical assay. Both PN‐EA/EOB and PN‐EA/POB supported the adhesion and proliferation of primary rat osteoblast cells in vitro. Furthermore, the enzymatic activity of the osteoblast cells cultured on the polymers was confirmed by the alkaline phosphatase activity. Thus, these biodegradable amino‐acid‐based polyphosphazenes are promising new materials for forming self‐setting bone cements. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Evaluation of alginate purification methods: Effect on polyphenol, endotoxin, and protein contamination
Authors: Dusseault Julie , Tam Susan K. , Ménard Martin , Polizu Stefania , Jourdan Guillaume , Yahia L'Hocine , Hallé Jean‐Pierre
Published: November 2005

Alginate, a polysaccharide extracted from brown seaweed, is widely used for the microencapsulation of islets of Langerhans, allowing their transplantation without immunosuppression. This natural polymer is known to be largely contaminated. The implantation of islets encapsulated using unpurified alginate leads to the development of fibrotic cell overgrowth around the microcapsules and normalization of the blood glucose is restricted to a very short period if it is achieved at all. Several research groups have developed their own purification method and obtained relatively good results. No comparative evaluation of the efficiencies of these methods has been published. We conducted an evaluative study of five different alginate preparations: a pharmaceutical‐grade alginate in its raw state, the same alginate after purification according to three different published methods, and a commercially available purified alginate. The results showed that all purification methods reduced the amounts of known contaminants, that is, polyphenols, endotoxins, and proteins, although with varying efficiencies. Increased viscosity of alginate solutions was observed after purification of the alginates. Despite a general efficiency in decreasing contamination levels, all of the purified alginates contained relatively high residual amounts of protein contaminants. Because proteins may be immunogenic, these residual proteins may have a role in persisting microcapsule immunogenicity. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
“Wet‐state” mechanical properties of three‐dimensional polyester porous scaffolds
Authors: Wu Linbo , Zhang Junchuan , Jing Dianying , Ding Jiandong
Published: November 2005

Porous poly(D,L‐lactic‐co‐glycolic acid) (PLGA) scaffolds under a simulated physiological environment were investigated to estimate their “true” mechanical properties, with emphasis on the effect of “wet‐state” on the compressive behaviors. The effect of the history of ethanol sterilization was also investigated. The studies were focused upon the “wet‐state” mechanical properties of polyester porous scaffolds, because the potential implants must be used under a wet environment. The measurements of three‐dimensional porous scaffolds composed of amorphous PLGA with five polymer formulations including poly(D,L‐lactic acid) (PDLLA) demonstrated that the mechanical properties of PLGA scaffolds significantly decreased in phosphate buffer saline solution (PBS) at 37°C and/or with an ethanol sterilization history, even though PLGA is a hydrophobic material. The decrease extent depends on the copolymer composition: when the porosity is about 90%, a PDLLA scaffold remained about 75–80% of initial mechanical properties in the dry state at 25°C, whereas PLGA 85:15, 75:25, and 65:35 scaffolds remained only about 10% or less, and the PLGA 50:50 scaffolds examined were not sufficiently strong for mechanical tests. If scaffolds were prewetted with ethanol ahead of prewetting with PBS, the mechanical properties further decreased compared with those merely prewetted with PBS. These phenomena were elucidated experimentally from plasticization of PLGA with water or ethanol, and the consequent reduction of glass transition temperature. The results might be helpful for designing polyester porous scaffolds for tissue engineering or in situ tissue induction applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Mesenchymal stem cell adhesion and spreading on microwave plasma‐nitrided titanium alloy
Authors: Clem William C. , Konovalov Valery V. , Chowdhury S. , Vohra Yogesh K. , Catledge Shane A. , Bellis Susan L.
Published: November 2005

Improved methods to increase surface hardness of metallic biomedical implants are being developed in an effort to minimize the formation of wear debris particles that cause local pain and inflammation. However, for many implant surface treatments, there is a risk of film delamination due to the mismatch of mechanical properties between the hard surface and the softer underlying metal. In this article, we describe the surface modification of titanium alloy (Ti‐6Al‐4V), using microwave plasma chemical vapor deposition to induce titanium nitride formation by nitrogen diffusion. The result is a gradual transition from a titanium nitride surface to the bulk titanium alloy, without a sharp interface that could otherwise lead to delamination. We demonstrate that vitronectin adsorption, as well as the adhesion and spreading of human mesenchymal stem cells to plasma‐nitrided titanium is equivalent to that of Ti‐6Al‐4V, while hardness is improved 3‐ to 4‐fold. These in vitro results suggest that the plasma nitriding technique has the potential to reduce wear, and the resulting debris particle release, of biomedical implants without compromising osseointegration; thus, minimizing the possibility of implant loosening over time. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Surface modification and initial adhesion events for intestinal epithelial cells
Authors: Hagerman E.M. , Chao S.H.H. , Dunn J.C.Y. , Wu B.M.
Published: November 2005

Rapid resealing of the mucosal epithelia is imperative following injuries to the small intestine because the mucosa is responsible for the adsorption of nutrients as well as providing a barrier to noxious agents present in the lumen. Tissue engineering may provide a possible solution for treating intestinal erosions, ulcerations, inflammatory bowel disease, and infection. Cell‐biomaterial interaction is a critical component in tissue engineering that can determine the success of the tissue construct. Cell‐biomaterial interactions can be enhanced by various types of surface modification, which promote integrin ligation leading to increased cell function. In order to relate the effect of surface adhesion molecules to signaling events and macroscopic cell response, an intestinal epithelial cell line, IEC‐6, was plated on fibronectin (receptor‐mediated) and poly‐L‐lysine (non‐specific) surfaces. Focal adhesion kinase (FAK) phosphorylation, cell spreading, and cell adhesion strength were measured. Results showed increases in FAK phosphorylation generally corresponded to increases in cell spreading and adhesion strength for IEC‐6 cells. Therefore, in a simplified system, initial adhesion and signaling mechanisms appeared to correspond to subsequent physical responses in IEC‐6 cells relevant to tissue engineering applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res, 2006
Ciprofloxacin‐releasing bioabsorbable polymer is superior to titanium in preventing Staphylococcus epidermidis attachment and biofilm formation in vitro
Authors: Niemelä Sanna‐Mari , Ikäheimo Irma , Koskela Markku , Veiranto Minna , Suokas Esa , Törmälä Pertti , Waris Timo , Ashammakhi Nureddin , Syrjälä Hannu
Published: November 2005

Antibiotic coating systems have been successfully used to prevent bacterial attachment and biofilm formation. Our purpose was to evaluate whether bioabsorbable polylactide‐co‐glycolide (PLGA) 80/20 on its own, and PLGA together with ciprofloxacin (PLGA+C) have any advantages over titanium in preventing Staphylococcus epidermidis attachment and biofilm formation in vitro. Cylindrical specimens of titanium, PLGA, and PLGA+C in triplicate were examined for S. epidermidis ATCC 35989 attachment and biofilm formation after incubation with a bacterial suspension of about 105 cfu/mL for 1, 3, 7, 14, and 21 days, using scanning electron microscopy. Growth inhibition properties of PLGA and PLGA+C cylinders were tested on agar plates. On days 1, 3, and 21, no bacterial attachment was seen in 19.5, 9.2, and 41.4% of the titanium specimens; in 18.4, 28.7, and 34.5% of the PLGA specimens; and in 57.5, 62.1, and 57.5% of the PLGA+C specimens, respectively. During the whole study period, no biofilm was observed on 74–93% of the titanium specimens, 58–78% of the PLGA specimens, and 93–100% of the PLGA+C specimens. PLGA+C showed clear bacterial growth inhibition on agar plates, while PLGA and titanium did not show any inhibition. PLGA+C bioabsorbable material was superior to titanium in preventing bacterial attachment and biofilm formation and may have clinical applicability, for example, in prevention of infection in trauma surgery or in the treatment of chronic osteomyelitis. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Late Glacial and Holocene vegetation history in the southern part of Transylvania (Romania): pollen analysis of two sequences from Avrig
Authors: Tantau Ioan , Reille Maurice , de Beaulieu Jacques‐Louis , Farcas Sorina
Published: November 2005

We present here the results of pollen analysis of two sequences of about 8.06 m and 11.90 m length, originating from two adjacent peat bogs in the southern part of Transylvania province, Romania (155 and 122 pollen spectra). The vegetation record, which is supported by 17 14C dates, begins in the Late Glacial interstadial when forest recolonisation began with the development of Pinus, without a pioneer Betula phase. Picea began to expand from regional refuges. After a well‐defined Younger Dryas, the Holocene opens with the expansion of Betula, Ulmus and Picea, followed, at about 10 400 cal. yr BP, by Fraxinus, Quercus and Tilia. The Corylus optimum is correlated with the Atlantic chronozone (after 8600 cal. yr BP). The local establishment of Carpinus occurred at about 6500 cal. yr BP, with a maximum at about 5700 cal. yr BP. Fagus pollen is regularly recorded after 8200 cal. yr BP. This taxon became dominant at about 3700 cal. yr BP. The first indications of human activities appear at around 7200 cal. yr BP. Copyright © 2005 John Wiley & Sons, Ltd.
Holocene evolution of the Mar Chiquita coastal lagoon area (Argentina) indicated by pollen analysis
Authors: Stutz Silvina , Prieto Aldo R. , Isla Federico I.
Published: November 2005

Palynologycal information was integrated with the aim to study vegetation history and environmental changes in Mar Chiquita coastal lagoon area (in the southeast of Buenos Aires province, Argentina) related to sea‐level fluctuations during the Holocene. Prior to 5000 yr BP a mosaic of psammophytic and halophytic communities developed on extensive sandy flats. Between 4000 and 2500 yr BP, during a period of sea‐level stabilisation, similar halophytic communities developed in the south and in the middle part of the present lagoon. Between 4500 and 3500 yr BP hydrophytic and halophytic communities developed in Laguna Hinojales. Beginning 2500 yr BP, when sea level was nearing its present position, modern plant communities became established. Pollen records suggest that littoral evolution of the area was much more complex than previous models have described, introducing new evidence of the geomorphological evolution of Mar Chiquita coastal lagoon. The estuarine environment was delimited by a system of barrier islands instead of a linear prograding barrier, as has been proposed. Copyright © 2005 John Wiley & Sons, Ltd.
Q‐switched ruby versus long‐pulsed dye laser delivered with compression for treatment of facial lentigines in Asians
Authors: Kono Taro , Manstein Dieter , Chan Henry H. , Nozaki Motohiro , Anderson R. Rox
Published: November 2005

Background and Objectives

Q‐switched lasers have been used for the treatment of lentigines but post‐inflammatory hyperpigmentation (PIH) can be an issue especially in Asians. The 595 nm long‐pulsed dye laser (LPDL) has been used for the treatment of vascular lesions and although it is well absorbed by oxyhemoglobin, it is also absorbed by melanin. To use this device for the treatment of facial lentigines, we attached a flat glass lens to the tip of the laser's handpiece, allowing compression of the skin during treatment. In doing so, eliminated the absorption by oxyhemoglobin. This prospective study aims to compare the efficacy and complications of such an approach to the use of Q‐switched ruby laser (QSRL) in the treatment of facial lentigines in Asians.

Study Design/Materials and Methods

Eighteen Asian patients (1 male, 17 female) with facial lentigines Fitzpatrick skin types III–IV were enrolled. One of the lentigines present was treated with LPDL by compression method and the other one was treated with QSRL. A LPDL emitting wavelength of 595 nm, spot size of 7 mm was used, with fluence between 10 and 13 J/cm2 and pulse duration of 1.5 milliseconds. Cryogen spray cooling was not used. A 694 nm QSRL was used with a spot size of 4 mm, fluence of 6–7 J/cm2, and pulse duration of 30 nanoseconds. Lightening of the lesions was assessed by reflectance spectrometer Erythema, hypo‐ or hyperpigmentation and scarring were also assessed by clinical examinators.

Results

The degree of clearing achieved with the two lasers was 70.3% and 83.3% for QSRL and LPDL, respectively. All QSRL treated areas developed erythema whereas only 4 of 18 LPDL treated areas developed erythema. Hyperpigmentation was seen in four patients after QSRL, but not after LPDL. There was no scarring or hypopigmentation.

Conclusions

LPDL delivered with a compression method is more effective than QSRL for facial lentigines. Complications after LPDL treatment were substantially less frequent than after QSRL. The addition of compression technique may allow “vascular” pulsed dye laser to be used for treating a variety of pigmented lesions. Lasers Surg. Med. 38:94–97, 2006. © 2005 Wiley‐Liss, Inc.
Continuous dependence on the heat source and non‐linear stability for convection with internal heat generation
Authors: Straughan Brian
Published: November 2005

It is shown that the solution to the boundary‐initial value problem for a heat‐conducting viscous fluid depends continuously on changes in the heat supply function, for the improperly posed backward in time problem. A non‐linear convection threshold is also determined for the problem of a layer of fluid heated internally (non‐uniformly), with zero neat flux on the lower boundary and constant‐temperature upper surface.
On a non‐stationary Ginzburg–Landau superconductivity model
Authors: Chen Zhiming , Hoffmann K.‐H. , Liang Jin
Published: November 2005

In this paper, we study a non‐stationary superconductivity model derived from Ginzburg–Landau macroscopic theory. By using gauge invariance and studying a linear problem with curl boundary conditions, we obtain the existence of solutions. The solution is unique in the sense of gauge equivalence.
Global solution to the full one‐dimensional Frémond model for shape memory alloys
Authors: Colli Pierluigi , Sprekels Jürgen
Published: November 2005

In this paper, we prove the existence and uniqueness of the solution to the one‐dimensional initial‐boundary value problem resulting from the Frémond thermomechanical model of structural phase transitions in shape memory materials. In this model, the free energy is assumed to depend on temperature, macroscopic deformation and phase fractions. The resulting equilibrium equations are the balance laws of (linear) momentum and energy, coupled with an evolution variational inequality for the phase fractions. Fourth‐order regularizing terms in the quasi‐stationary momentum balance equation are not necessary, and, as far as we know for the first time, all the non‐linear terms of the energy balance equation are taken into account.