bluuebunny/crossref_metadata_2025 huggingface dataset:
Configurational forces and couples for crack propagation
Authors: Jaric Jovo , Golubovic Zoran
Published: March 2008

Following the approach of Gurtin and Podio-Guidugli (1998), the problem of crack propagation based on the notion of configurational forces and couples in micropolar continua is considered. .
Stochastic homogenization and macroscopic modelling of composites and flow through porous media
Authors: Telega Jozef , Bielski Wlodzimierz
Published: March 2008

The aim of this contribution is mainly twofold. First, the stochastic two-scale convergence in the mean developed by Bourgeat et al. [13] is used to derive the macroscopic models of: (i) diffusion in random porous medium, (ii) nonstationary flow of Stokesian fluid through random linear elastic porous medium. Second, the multi-scale convergence method developed by Allaire and Briane [7] for the case of several microperiodic scales is extended to random distribution of heterogeneities characterized by separated scales (stochastic reiterated homogenization). .
Finite-strain thermoelasticity based on multiplicative decomposition of deformation gradient
Authors: Vujosevic L. , Lubarda V.A.
Published: March 2008

The constitutive formulation of the finite-strain thermoelasticity is revisited within the thermodynamic framework and the multiplicative decomposition of the deformation gradient into its elastic and thermal parts. An appealing structure of the Helmholtz free energy is proposed. The corresponding stress response and the entropy expressions are derived. The results are specified in the case of quadratic dependence of the elastic strain energy on the finite elastic strain. The specific and latent heats are discussed, and the comparison with the results of the classical thermoelasticity are given. .
Effects of chemical reaction on moving isothermal vertical plate with variable mass diffusion
Authors: Muthucumaraswamy R.
Published: March 2008

An exact solution to the problem of flow past an impulsively started infinite vertical isothermal plate with variable mass diffusion is presented here, taking into account of the homogeneous chemical reaction of first-order. The dimensionless governing equations are solved by using the Laplace - transform technique. The velocity and skin-friction are studied for different parameters like chemical reaction parameter, Schmidt number and buoyancy ratio parameter. It is observed that the veloc?ity increases with decreasing chemical reaction parameter and increases with increasing buoyancy ratio parameter.
Ferrofluid lubrication of a parallel plate squeeze film bearing
Authors: Shah Rajesh , Bhat M.V.
Published: March 2008

We derived a Reynolds type equation for a ferrofluid lubrication in a squeeze film between two circular plates using Jenkins model and considering combined effects of rotation of the plates, anisotropic permeability in the porous matrix and slip velocity at the interface of porous matrix and film region. We used it to study the case of a parallel-plate squeeze film bearing. Expressions were obtained for dimensionless pressure, load capacity and response time. Computed values were displayed some in tabular form and some in graphical form. The load capacity decreased with increasing values of the radial permeability and attained a minimum when the plates rotated in the opposite directions with nearly the same speed. It increased with increasing values of the axial permeability or material constant of Jenkins model and attained a maximum when the value of the material constant was near unity. It increased or decreased for increasing values of the speed of rotation of the upper plate according as the value of the material constant is zero or not. The response time slowly decreased with increasing values of the radial permeability, speed of rotation of upper plate or the material constant. But, it increased with increasing values of the axial permeability and attained a maximum when the plates rotated in opposite directions with nearly the same speed. Anisotropic permeability affected the bearing characteristics considerably.
Restoration of the symmetries broken by reversible growth in hyperelastic bodies
Authors: Grillo Alfio , Federico Salvatore , Giaquinta Gaetano , Herzog Walter , La Rosa
Published: March 2008

In this paper, we interpret the development of material in homogeneities in continuum, hyper elastic bodies in the presence of reversible growth in terms of broken symmetries [1]. By applying Noether's Theorem [1, 2, 3, 4], we find a set of equations yielding the fields necessary to compensate for the broken symmetry. As growth occurs, these fields provide for an instantaneously updated reference configuration of the body, and are responsible for the dynamical restoring of the body symmetries. In addition, we propose to use these compensating fields in order to generalize the definition of the transplant operator given in [5,6]. This work has been motivated by the current theoretical investigations on the biomechanical aspects of growth in particular cartilage.
Computer simulations of blood flow with mass transport through the carotid artery bifurcation
Authors: Filipovic Nenad , Kojic Milos
Published: March 2008

The current paradigm for clinical diagnostic for the treatment of vascular disease relies exclusively on diagnostic imaging data to define the present state of the patient, empirical data to evaluate the efficacy of prior treatments for similar patients. These techniques are insufficient to predict the outcome of a given treatment for an individual patient. We here propose a new paradigm of predictive medicine where physician could use computational simulation to construct and evaluate a specific geometrical/anatomical model to predict the outcome for an individual patient. For this purpose it is necessary to develop a complex software system which combines user friendly interface, automatic solid modeling, automatic finite mesh generation, computational fluid dynamics and post-processing visualization. The flow dynamics is defined according to the incompressible Navier-Stokes equations for Newtonian and non-Newtonian fluids. Mass transport of oxygen and macromolecules is modeled by the convection diffusion equation and coupled with flow dynamics. The computer simulations are based upon finite element analysis where the new computer methods for coupling oxygen transport and fluid flow are described. The comparison results shows a good agreement between clinical observation for critical zones of flow separation, flow recirculation, low wall shear stresses which may contribute to the development of atherosclerotic diseases.
Static inelastic analysis of steel frames with flexible connections
Authors: Nefovska-Danilovic M. , Sekulovic M.
Published: March 2008

The effects of connection flexibility and material yielding on the behavior of plane steel frames subjected to static (monotonic) loads are presented in this paper. Two types of material nonlinearities are considered: flexible nodal connections and material yielding, as well as geometric nonlinearity of the structure. To account for material yielding, a plastic hinge concept is adopted. A flexible connection is idealized by nonlinear rotational spring. Plastic hinge is also idealized by nonlinear rotational spring attached in series with the rotational spring that accounts for connection flexibility. The stiffness matrix for the beam with flexible connections and plastic hinges at its ends is obtained. To illustrate the validity and accuracy of the proposed numerical model, several examples have been conducted.
Hydrodynamic forces on two moving discs
Authors: Burton D.A. , Gratus J. , Tucker R.W.
Published: March 2008

We give a detailed presentation of a flexible method for constructing explicit expressions of irrotational and incompressible fluid flows around two rigid circular moving discs. We also discuss how such expressions can be used to compute the fluid-induced forces and torques on the discs in terms of Killing drives. Conformal mapping techniques are used to identify a meromorphic function on an annular region in C with a flow around two circular discs by a Mobius transformation. First order poles in the annular region correspond to vortices outside of the two discs. Inflows are incorporated by putting a second order pole at the point in the annulus that corresponds to infinity.
Approximate solution for SPP with discontinuous source term
Authors: Adzic Nevenka , Ovcin Z.
Published: March 2008

In this paper we shall consider self-adjoint singularly perturbed problem described by the ordinary differential equation of second order with small parameter multiplying the highest derivative and discontinuous source term, and the appropriate boundary conditions, which describes steady state of certain flow problems. The solution displays both boundary layers and an interior layer. The domain decomposition will be performed determining layer subintervals which are adapted to polynomial approximation. The division points for the interior layer are determined by the procedure similar to the one for boundary layers using appropriate resemblance function. The solution out of boundary layer is approximated by the solution of the reduced problem, and the layer solutions is approximated by truncated orthogonal series giving a smooth approximate solution upon the entire interval. The coefficients of the truncated series are evaluated using pseudospectral technique. The rate of convergence is examined and the order-of-magnitude of the error is given, using the principle of inverse monotonicity and the behavior of the pseudospectral approximations. Numerical example is included and it shows the high accuracy of the presented method. .
Modeling of a light elastic beam by a system of rigid bodies
Authors: Salinic Slavisa
Published: March 2008

This paper has shown that a light elastic beam, in the case of small elastic deformations, can be modeled by a kinematic chain without branching composed of rigid bodies which are connected by passive revolute or prismatic joints with corresponding springs in them. Elastic properties of the beam are modeled by the springs introduced. The potential energy of the elastic beam is expressed as a function of components of the vector of elastic displacement and the vector of elastic rotation calculated for the elastic centre of the beam, which results in the diagonal stiffness matrix of the beam. As the potential energy of the introduced system of bodies with springs is expressed in the function of relative joint displacements, the diagonal stiffness matrix is obtained. In addition, these two stiffness matrices are equal. The modeling process has been demonstrated on the example of an elastic beam rotating about a fixed vertical axis, with a rigid body whose mass is considerably larger than the beam mass fixed to its free end. Differential equations of motion have been formed for this mechanical system. The modeling technique described here aims at expanding of usage of well developed methods of dynamics of systems of rigid bodies to the analysis of systems with elastic bodies. .
Mixed convection flow past a horizontal plate
Authors: Savic Lj. , Steinrück H.
Published: March 2008

The mixed convection flow past a horizontal plate being aligned through a small angle of attack to a uniform free stream will be considered in the limit of large Reynolds number and small Richardson number. Even a small angle of inclination of the wake is sufficient for the buoyancy force to accelerate the flow in the wake which causes a velocity overshoot in the wake. Moreover a hydrostatic pressure difference across the wake induces a correction to the potential flow which influences the inclination of the wake. Thus the wake and the correction of the potential flow have to be determined simultaneously. However, it turns out that solutions exist only if the angle of attack is sufficiently large. Solutions are computed numerically and the influence of the buoyancy on the lift coefficient is determined.
The role of material in homogeneities in biological growth
Authors: Grillo A. , Zingali G. , Federico S. , Herzog W. , Giaquinta G.
Published: March 2008

We investigate the influence of the material in homogeneities that are generated by an isotropic growth on the source of mass acting within a growing living tissue. In order to do that, we need to study the interaction between these material in homogeneities and the chemical agents dissolved within the tissue. For this purpose, we use some ideas and methods from Condensed Matter Physics (e.g., the Path Integral technique employed in modeling Brownian processes) and apply them to the Continuum Mechanics description of volumetric Growth. We believe that this approach may provide new physical insight into the interactions between the macroscopic dynamics of living systems and the evolution of the subsystems which activate biological processes.
Control of industrial robot using neural network compensator
Authors: Rankovic Vesna , Nikolic Ilija
Published: March 2008

In the paper is considered synthesis of the controller with tachometric feedback with feed forward compensation of disturbance torque, velocity and acceleration errors. It is difficult to obtain the desired control performance when the control algorithm is only based on the robot dynamic model. We use the neural network to generate auxiliary joint control torque to compensate these uncertainties. The two-layer neural network is used as the compensator. The main task of control system here is to track the required trajectory. Simulations are done in MATLAB for RzRyRy robot minimal configuration.
Flow around a sphere in an oscillating stream of a dusty fluid
Authors: Srivastava A.C. , Srivastava P.K.
Published: March 2008

The oscillation of a stream of dusty fluid in the presence of a sphere has been discussed. The effect of interaction of curvature and viscosity has been included in the boundary layer equations. The dust particles slip on the surface of the sphere and the slip velocity is a function of relaxation time of the dust particles but is independent of mass concentration of the gas. Dust particles shift the steady secondary flow towards the main flow and increase the resistance on the sphere. .
MHD and radiation effects on moving isothermal vertical plate with variable mass diffusion
Authors: Muthucumaraswamy R. , Janakiraman B.
Published: March 2008

An analysis is performed to study the effects of thermal radiation on unsteady free convective flow over a moving vertical plate with mass transfer in the presence of magnetic field. The fluid considered here is a gray, absorbing-emitting radiation but a non- scattering medium. The plate temperature is raised to T 0 and the concentration level near the plate is also raised linearly with time. The dimensionless governing equations are solved using the Laplace transform technique. The velocity, temperature and concentration are studied for different parameters like the magnetic field parameter, radiation parameter, thermal Grashof number, mass Grashof number and time. It is observed that the velocity decreases with increasing magnetic field parameter or radiation parameter. .
Transient radiative hydromagnetic free convection flow past an impulsively started vertical plate with uniform heat and mass flux
Authors: Prasad Ramachandra , Reddy Bhaskar , Muthucumaraswamy R.
Published: March 2008

The interaction of free convection with thermal radiation of viscous incompressible MHD unsteady flow past an impulsively started vertical plate with uniform heat and mass flux is analyzed. This type of problem finds application in many technological and engineering fields such as rocket propulsion systems, space craft re-entry aerothermodynamics, cosmical flight aerodynamics, plasma physics, glass production and furnace engineering .The Rosseland approximation is used to describe the radiative heat transfer in the limit of the optically thin fluid. The non-linear, coupled equations are solved using an implicit finite difference scheme of Crank-Nicolson type. Velocity, temperature and concentration of the flow have been presented for various parameters such as thermal Grashof number, mass Grashof number, Prandtl number, Schmidt number, radiation parameter and magnetic parameter. The local and average skin friction, Nusslet number and Sherwood number are also presented graphically. It is observed that, when the radiation parameter increases the velocity and temperature decrease in the boundary layer. .
Analysis of stress and strain in a rotating disk mounted on a rigid shaft
Authors: Alexandrova Nelli , Alexandrov Sergei , Vila Real
Published: March 2008

The plane state of stress in an elastic-perfectly plastic isotropic rotating annular disk mounted on a rigid shaft is studied. The analysis of stresses, strains and displacements within the disk of constant thickness and density is based on the Mises yield criterion and its associated flow rule. It is observed that the plastic deformation is localized in the vicinity of the inner radius of the disk, and the disk of a sufficiently large outer radius never becomes fully plastic. The semi-analytical method of stress-strain analysis developed is illustrated by some numerical examples. .
Suppression of torsional oscillations based on IMPACT controlling structure
Authors: Matijevic Milan , Stojic Milic , Vukosavic Slobodan , Stefanovic Miladin
Published: March 2008

In this paper, an algorithm for suppression of the torsional oscillations, in the computer controlled servo systems, is purposed. A few modification of the IMPACT structure (Internal Model Principle and Control Together) in the digitally controlled electrical drives are proposed. The IMPACT structure suitable for suppression of the torsional oscillations in a servo system with the flexible coupling has been presented. The approach, proposed in this paper, gives better solutions for the problem of the mechanical resonance in the modern servo drive than the previous ones. The presented structure is simple with a small number of adjustable parameters that could be easily set to achieve the desired robust, filtering, and dynamic properties of the system.
Wave propagation at the human muscle-compact bone interface
Authors: Hsia Shao-Yi , Chiu Shih-Ming , Cheng Jyin-Wen
Published: March 2008

Due to the improvement of the signal processing and image technology, the clinical ultrasound system becomes an important tool to assist doctors in detecting diseases. Hence, it is necessary to know the biological effects of ultrasound in human tissue. In ultrasonic waves, the discrepancy between classic elasticity and experimental elasticity becomes a particularly important problem, especially when there are higher frequencies and smaller wavelengths, i.e., in the case of wave propagation in human muscle and compact bone. Consequently, the influence of the microstructure is important and this fact leads to the generation of new types of waves unknown in classic elasticity. General continuum theories, such as couple stress theory and micropolar theory, have degrees of freedom in addition to those of classic elasticity. Such theories are thought to be applicable to composites with granular or porous structure, effective chiral composite, and human compact bone. In this work, a theoretical analysis concerning the reflected and transmitted fields of an incident plane wave P propagating at the human muscle-compact bone interface has been investigated. The results show that the wave fields are affected by microstructures of the human bone. Knowledge of this occurrence may offer some contribution to the understanding of the ultrasound propagation in the biological effects of human tissue.
Theoretical study of chemical reaction effects on vertical oscillating plate with variable temperature
Authors: Muthucumaraswamy R. , Meenakshisundaram S.
Published: March 2008

An exact solution to the flow of a viscous incompressible unsteady flow past an infinite vertical oscillating plate with variable temperature and mass diffusion is presented here, taking into account of the homogeneous chemical reaction of first-order. Both the plate temperature and the concentration level near the plate are raised linearly with respect to time. The dimensionless governing equations has been obtained by the Laplace transform method, when the plate is oscillating harmonically in its own plane. The effects of velocity and concentration are studied for different parameters like phase angle, chemical reaction parameter, thermal Grashof number, mass Grashof number, Schmidt number and time are studied. The solutions are valid only for small values of time t. It is observed that the velocity increases with decreasing phase angle ?t or chemical reaction parameter. .
Skin-friction for unsteady free convection MHD flow between two heated vertical parallel plates
Authors: Singha Gopal , Deka P.N.
Published: March 2008

Unsteady viscous incompressible free convection flow of an electrically conducting fluid between two heated vertical parallel plates is considered in the presence of a uniform magnetic field applied transversely to the flow. The induce field along the lines of motion varies transversely to the flow and the fluid temperature changing with time. An analytical solution for velocity, induced field and the temperature distributions are obtained for small and large magnetic Reynolds numbers. The skin-friction at the two plates is obtained. Velocity distribution, induced field and skin-friction are plotted against the distance from the plates. It has been observed that with the increase in Rm, the magnetic Reynolds number, at constant M, the Hartmann number, leads to an increase in the skin-friction gradually. But with the increase in M, at constant Rm, the skin-friction decreases.
Numerical estimation of aircrafts' unsteady lateral-directional stability derivatives
Authors: Maricic N.L.
Published: March 2008

A technique for predicting steady and oscillatory aerodynamic loads on general configuration has been developed. The prediction is based on the Doublet-Lattice Method, Slender Body Theory and Method of Images. The chord and span wise loading on lifting surfaces and longitudinal bodies (in horizontal and vertical plane) load distributions are determined. The configuration may be composed of an assemblage of lifting surfaces (with control surfaces) and bodies (with circular cross sections and a longitudinal variation of radius). Loadings predicted by this method are used to calculate (estimate) steady and unsteady (dynamic) lateral-directional stability derivatives. The short outline of the used methods is given in [1], [2], [3], [4] and [5]. Applying the described methodology software DERIV is developed. The obtained results from DERIV are compared to NASTRAN examples HA21B and HA21D from [4]. In the first example (HA21B), the jet transport wing (BAH wing) is steady rolling and lateral stability derivatives are determined. In the second example (HA21D), lateral-directional stability derivatives are calculated for forward- swept-wing (FSW) airplane in antisymmetric quasi-steady maneuvers. Acceptable agreement is achieved comparing the results from [4] and DERIV.
Radiation and mass transfer effects on an unsteady MHD free convection flow past a heated vertical plate in a porous medium with viscous dissipation
Authors: Prasad Ramachandra , Reddy Bhaskar
Published: March 2008

An unsteady, two-dimensional, hydromagnetic, laminar free convective boundary-layer flow of an incompressible, Newtonian, electrically-conducting and radiating fluid past an infinite heated vertical porous plate with heat and mass transfer is analyzed, by taking into account the effect of viscous dissipation. The dimensionless governing equations for this investigation are solved analytically using two-term harmonic and non-harmonic functions. Numerical evaluation of the analytical results is performed and graphical results for velocity, temperature and concentration profiles within the boundary layer and tabulated results for the skin-friction coefficient, Nusselt number and Sherwood number are presented and discussed. It is observed that, when the radiation parameter increases, the velocity and temperature decrease in the boundary layer, whereas when thermal and solutal Grashof increases the velocity increases.
5-Lipoxygenase, but Not 12/15-Lipoxygenase, Contributes to Degeneration of Retinal Capillaries in a Mouse Model of Diabetic Retinopathy
Authors: Gubitosi-Klug Rose A. , Talahalli Ramaprasad , Du Yunpeng , Nadler Jerry L. , Kern Timothy S.
Published: March 2008

OBJECTIVE—Lipoxygenases are regulators of chronic inflamation and oxidative stress generation. We evaluated the role of 5- and 12-lipoxygenases in the development of diabetic retinopathy.

RESEARCH DESIGN AND METHODS—Wild-type mice, 5-lipoxygenase–deficient mice, and 12/15-lipoxygenase–deficient mice were assessed 1) after 9 months of diabetes for retinal histopathology and leukotriene receptor expression and 2) after 3 months of diabetes for leukostasis and retinal superoxide generation.

RESULTS—Diabetic wild-type mice developed the expected degeneration of retinal capillaries and pericytes and increases in both leukostasis and superoxide production (P < 0.006). We found no evidence of diabetes-induced degeneration of retinal ganglion cells in these animals. The vascular histopathology was significantly inhibited in 5-lipoxygenase–deficient mice, but not in 12/15-lipoxygenase–deficient mice. Retinas from diabetic 5-lipoxygenase–deficient mice also had significantly less leukostasis, superoxide production, and nuclear factor-κB (NF-κB) expression (all P < 0.006), whereas retinas from diabetic 12/15-lipoxygenase–deficient mice had significantly less leukostasis (P < 0.005) but not superoxide production or NF- κB expression. Retinas from diabetic wild-type mice were enriched with receptors for the 5-lipoxygenase metabolite leukotriene B4. Diabetes-induced histological and biochemical alterations were significantly reduced in 5-lipoxygenase–deficient mice, but not 12/15-lipoxygenase–deficient mice.

CONCLUSIONS—5-Lipoxygenase represents a novel pathway for therapeutic intervention of diabetic retinopathy.
A Rare Mutation in ABCC8/SUR1 Leading to Altered ATP-Sensitive K+ Channel Activity and β-Cell Glucose Sensing Is Associated With Type 2 Diabetes in Adults
Authors: Tarasov Andrei I. , Nicolson Tamara J. , Riveline Jean-Pierre , Taneja Tarvinder K. , Baldwin Stephen A. , Baldwin Jocelyn M. , Charpentier Guillaume , Gautier Jean-François , Froguel Philippe , Vaxillaire Martine , Rutter Guy A.
Published: March 2008

OBJECTIVE— ATP-sensitive K+ channels (KATP channels) link glucose metabolism to the electrical activity of the pancreatic β-cell to regulate insulin secretion. Mutations in either the Kir6.2 or sulfonylurea receptor (SUR) 1 subunit of the channel have previously been shown to cause neonatal diabetes. We describe here an activating mutation in the ABCC8 gene, encoding SUR1, that is associated with the development of type 2 diabetes only in adults.

RESEARCH DESIGN AND METHODS— Recombinant KATP channel subunits were expressed using pIRES2-based vectors in human embryonic kidney (HEK) 293 or INS1(832/13) cells and the subcellular distribution of c-myc–tagged SUR1 channels analyzed by confocal microscopy. KATP channel activity was measured in inside-out patches and plasma membrane potential in perforated whole-cell patches. Cytoplasmic [Ca2+] was imaged using Fura-Red.

RESULTS— A mutation in ABCC8/SUR1, leading to a Y356C substitution in the seventh membrane-spanning α-helix, was observed in a patient diagnosed with hyperglycemia at age 39 years and in two adult offspring with impaired insulin secretion. Single KATP channels incorporating SUR1-Y356C displayed lower sensitivity to MgATP (IC50 = 24 and 95 μmol/l for wild-type and mutant channels, respectively). Similar effects were observed in the absence of Mg2+, suggesting an allosteric effect via associated Kir6.2 subunits. Overexpression of SUR1-Y356C in INS1(832/13) cells impaired glucose-induced cell depolarization and increased in intracellular free Ca2+ concentration, albeit more weakly than neonatal diabetes–associated SUR1 mutants.

CONCLUSIONS— An ABCC8/SUR1 mutation with relatively minor effects on KATP channel activity and β-cell glucose sensing causes diabetes in adulthood. These data suggest a close correlation between altered SUR1 properties and clinical phenotype.
Removal of reactive dye brilliant red HE-3B from aqueous solutions by hydrolyzed polyacrylonitrile fibres: equilibrium and kinetics modelling
Authors: Bilba Doina , Suteu Daniela , Malutan Theodor
Published: March 2008

A cheap and efficient fibrous hydrolyzed polyacrylonitrile (HPAN) sorbent was obtained by alkaline hydrolysis of Romanian polyacrylonitrile fibres. Scanning electronic microscopy and infrared spectroscopy were used to characterize the hydrolyzed product and to confirm its functionalization. The adsorptive potential of the proposed sorbent for reactive dye Brilliant Red HE-3B removal from aqueous solutions of pH=2 was examined by the batch technique as a function of dye concentration, temperature solution and contact time. The Freundlich, Langmuir and Dubinin-Radushkevich adsorption models were applied to describe equilibrium sorption data and to determine the corresponding isotherm constants. The thermodynamic parameters ΔG, ΔH and ΔS were also determined; the values obtained show that sorption of reactive dye on HPAN fibres is a spontaneous, endothermic and entropy-driven process. The kinetics of sorption of the reactive dye were analyzed using pseudo-first order and pseudo-second order kinetic models. The kinetic data fitted well to pseudo-second order kinetics, indicating the chemisorption of reactive dye onto the fibrous sorbent. The sorption mechanism of the dye onto hydrolyzed fibres was confirmed by FTIR spectroscopy. The dye-loaded HPAN sorbent can be regenerated by treatment with 0.1M NaOH and the regenerated sorbent may be reused in several adsorption-desorption cycles. The results of this study provided evidence that the HPAN fibres are effective for removing reactive dye Brilliant Red HE-3B from aqueous effluents.
Electrochemical preparation and in situ characterization of poly(3-methylpyrrole) and poly(3-methylpyrrole-cyclodextrin) films on gold electrodes
Authors: Arjomandi Jalal , Holze Rudolf
Published: March 2008

A Electrosynthesis of conducting poly(3-methylpyrrole) (P3MPy) and poly(3-methylpyrrole-2,6-dimethyl-β-cyclodextrin) (poly(3MPy-β-DMCD)) films on a gold electrode in acetonitrile electrolyte solution containing lithium perchlorate has been carried out by potential cycling. Products were characterized with cyclic voltammetry CV, in situ UV-Vis spectroscopy, and in situ resistance measurements. Electrosynthesis of poly(3MPy-β-DMCD) started with a (1:1) (3MPy-β-DMCD) supramolecular cyclodextrin CD complex of 3-methylpyrrole characterized with proton NMR spectroscopy. The oxidation peak of poly(3MPy-β-DMCD) in CVs is shifted to more positive values than P3MPy. In situ resistance measurements show that the resistance of poly(3MPy-β-DMCD) is higher than of P3MPy by approximately an order of magnitude. Minimum resistance can be observed for P3MPy and poly(3MPy-β-DMCD) at 0.40 E Ag/AgClE Ag/AgClIn situ UV-Vis spectroelectrochemical data for both films prepared potentiodynamically by cycling the potential in the range −0.20 E Ag/AgCl
Evolution of the polarization of electromagnetic waves in weakly anisotropic inhomogeneous media — a comparison of quasi-isotropic approximations of the geometrical optics method and the Stokes vector formalism
Authors: Kravtsov Yury , Bieg Bohdan
Published: March 2008

The main methods describing polarization of electromagnetic waves in weakly anisotropic inhomogeneous media are reviewed: the quasi-isotropic approximation (QIA) of geometrical optics method that deals with coupled equations for electromagnetic field components, and the Stokes vector formalism (SVF), dealing with Stokes vector components, which are quadratic in electromagnetic field intensity. The equation for the Stokes vector evolution is shown to be derived directly from QIA, whereas the inverse cannot be true. Derivation of SVF from QIA establishes a deep unity of these two approaches, which happen to be equivalent up to total phase. It is pointed out that in contrast to QIA, the Stokes vector cannot be applied for a polarization analysis of the superposition of coherent electromagnetic beams. Additionally, the ability of QIA to describe a normal modes conversion in inhomogeneous media is emphasized.
Dynamic rotational characteristics of actinides on empirical approach
Authors: Kaczmarczyk Maria , Korejwo Andrzej
Published: March 2008

In the paper calculation of the moments of inertia for nuclei from the region 87 ≤ Z ≤ 100 and 130 ≤ N ≤ 156 was made in dependence on the angular momentum of their rotational states. The experimental values of the moments of inertia were calculated for rotational energy of the classic rotor in its quantum form, with the use of a simple formula. The moment of inertia term appearing in the formula was treated as a variable. The calculations were carried out on the basis of experimental data for the energies of the rotational levels for 51 bands built on ground states for even-even nuclei and for nuclei with odd mass number A. In addition, 30 rotational bands built on excited states were also analysed in the investigated region in case of even-even nuclei. For many bands and nuclei the considered dependence of the moment of inertia on angular momentum has been found in the analytical form by fitting polynomials to the experimental data. It turned out that obtained results for the moments of inertia made it possible to describe the energies of rotational levels with a relative deviation not greater or only slightly greater than 1%. In general, in the case of 12 bands of ground level the maximum relative deviation of obtained level energies is smaller than 1%.
Recurrence of retroperitoneal fibrosis with pancreatic involvement — the importance of imaging methods
Authors: Djerassi Regina , Krupev Martin , Nikolova Milena , Naumov Nikolai , Marianovski Valeri , Elenkov Chavdar , Postadjian Arman
Published: March 2008

Retroperitoneal fibrosis (RPF) is a rare disease associated with the development of chronic inflammation and fibrogenesis in the retroperitoneal space. The disease usually manifests with acute or acute over chronic renal failure and/or urosepsis. Pancreatic involvement in RPF is rare but has been described in the literature. The diagnosis of RPF is made mainly by imaging methods. Abdominal echography scan reveals the presence of an obstruction with or without inflammation; computed tomography and magnetic resonance imaging show the type and the spreading of fibrosis. Here, we report a 50-year-old female patient diagnosed with RPF during operative intervention in 2003. Initial treatment with corticosteroids and tamoxifen lead to remission. In 2007, late recurrence was observed, with tumor-like lesions over the upper, posterior, and anterior surfaces of the pancreas, spreading to intraperitoneal structures and more pronounced on the left side. Abdominal echography on day 30 showed that corticosteroid treatment lead to a decrease in the tumor-like lesions.
Identification of the DNA binding element of the human ZNF300 protein
Authors: Qiu Hongling , Xue Lu , Gao Li , Shao Huanjie , Wang Di , Guo Mingxiong , Li Wenxin
Published: March 2008

The human ZNF300 gene is a member of the KRAB/C2H2 zinc finger gene family, the members of which are known to be involved in various developmental and pathological processes. Here, we show that the ZNF300 gene encodes a 68-kDa nuclear protein that binds DNA in a sequence-specific manner. The ZNF300 DNA binding site, C(t/a)GGGGG(c/g)G, was defined via a random oligonucleotide selection assay, and the DNA binding site was further confirmed by electrophoretic mobility shift assays. A potential ZNF300 binding site was found in the promoter region of the human IL-2Rβ gene. The results of electrophoretic mobility shift assays indicated that ZNF300 bound to the ZNF300 binding site in the IL-2Rβ promoter in vitro. Transient co-transfection assays showed that ZNF300 could activate the IL-2Rβ promoter, and that the activation was abrogated by the mutation of residues in the ZNF300 binding site. Identifying the DNA binding site and characterizing the transcriptional regulation property of ZNF300 would provide critical insights into its potential as a transcriptional regulator.
The cell type-specific effect of TAp73 isoforms on the cell cycle and apoptosis
Authors: Holcakova Jitka , Ceskova Pavla , Hrstka Roman , Muller Petr , Dubska Lenka , Coates Philip , Palecek Emil , Vojtesek Borivoj
Published: March 2008

p73, a member of the p53 family, exhibits activities similar to those of p53, including the ability to induce growth arrest and apoptosis. p73 influences chemotherapeutic responses in human cancer patients, in association with p53. Alternative splicing of the TP73 gene produces many p73 C- and N-terminal isoforms, which vary in their transcriptional activity towards p53-responsive promoters. In this paper, we show that the C-terminal spliced isoforms of the p73 protein differ in their DNA-binding capacity, but this is not an accurate predictor of transcriptional activity. In different p53-null cell lines, p73β induces either mitochondrial-associated or death receptor-mediated apoptosis, and these differences are reflected in different gene expression profiles. In addition, p73 induces cell cycle arrest and p21WAF1 expression in H1299 cells, but not in Saos-2. This data shows that TAp73 isoforms act differently depending on the tumour cell background, and have important implications for p73-mediated therapeutic responses in individual human cancer patients.
Using Past Data to Enhance Small Sample DIF Estimation: A Bayesian Approach
Authors: Sinharay Sandip , Dorans Neil J. , Grant Mary C. , Blew Edwin O.
Published: March 2008

Test administrators often face the challenge of detecting differential item functioning (DIF) with samples of size smaller than that recommended by experts. A Bayesian approach can incorporate, in the form of a prior distribution, existing information on the inference problem at hand, which yields more stable estimation, especially for small samples. A large volume of past data is available for many operational tests and such data could be used to establish prior distributions for a Bayesian DIF analysis. This article discusses how to perform such an analysis. The suggested approach is found to be more conservative and preferable with respect to several overall criteria than the existing DIF detection methods in a realistic simulation study.
Consequences of Unmodeled Nonlinear Effects in Multilevel Models
Authors: Bauer Daniel J. , Cai Li
Published: March 2008

Applications of multilevel models have increased markedly during the past decade. In incorporating lower-level predictors into multilevel models, a key interest is often whether or not a given predictor requires a random slope, that is, whether the effect of the predictor varies over upper-level units. If the variance of a random slope significantly differs from zero, the focus of the analysis may then shift to explaining this heterogeneity with upper-level predictors through the testing of cross-level interactions. As shown in this article, however, both the variance of the random slope and the cross-level interaction effects may be entirely spurious if the relationship between the lower-level predictor and the outcome is nonlinear in form but is not modeled as such. The importance of conducting diagnostics to detect nonlinear effects is discussed and demonstrated via an empirical example.
Hemiarthroplasty in the Treatment of Hallux Rigidus
Authors: Sorbie Charles , Saunders Gerald Anthony Briden
Published: March 2008

Background: Osteoarthritis of the first metatarsophalangeal (MTP) joint is a painful, disabling condition. It can interfere with the ability to run and even walk without pain. An implant of cobalt-chrome steel alloy to replace the base of the proximal phalanx is one solution. The purpose of this study is to review our results with one of these implants. Materials and Methods: A series of 23 cases of hemiarthroplasty for the treatment of hallux rigidus from June 2000 to October 2001 has been evaluated using the AOFAS rating system, and the results are presented. Results: The average preoperative AOFAS score was 57 (range, 39 to 80). The AOFAS score after hemiarthroplasty was 88 (range, 75 to 100) at last followup (34 to 72 months). There were no perioperative complications except for a small hematoma. Only one patient has required further surgery after 3 years for worsening of a preexisting tendency to hallux valgus. Conclusion: A hemiarthroplasty retained, in most cases, joint mobility, strength, and alignment while relieving pain. There was no evidence, at last followup, of component loosening or osteolysis.
The Minimally Invasive Osteotomy “S.E.R.I.” (Simple, Effective, Rapid, Inexpensive) for Correction of Bunionette Deformity
Authors: Giannini Sandro , Faldini Cesare , Vannini Francesca , Digennaro Vitantonio , Bevoni Roberto , Luciani Deianira
Published: March 2008

Background: A bunionette is a deformity of the fifth metatarsal bone with a varus deviation of the toe which can require surgical correction. Although numerous bony or soft tissue surgical procedures have been described, the ideal treatment has not yet been identified. The aim of this study was to retrospectively evaluate the results of a series of 50 consecutive feet affected by symptomatic bunionette deformity treated by S.E.R.I. (simple, effective, rapid, inexpensive) osteotomy. Materials and Methods: Between February 1998 and March 2004, 50 feet with symptomatic type II-III bunionette deformity in 32 patients (18 bilateral) underwent S.E.R.I osteotomy. The average age of the patients at the time of operation was 33 ± 13 years. The average followup was 4.8 (range, 2 to 8) years. Results: The average modified lesser toe AOFAS score increased from 62.8 ± 15.2 points preoperatively to 94 ± 6.8 points at last followup ( p < 0.0005). The average fifth metatarsophalangeal (MTP) angle decreased from 16.8 ± 5.1 degrees preoperatively to 7.9 ± 3.1 degrees at final followup ( p < 0.0005). The 4–5 intermetatarsal angle (I.M.A) averaged 12 ± 1.7 degrees preoperatively, while postoperatively was 6.7 ± 1.7 degrees ( p < 0.0005). Complications included a skin inflammatory reaction around the Kirschner wire and 2 symptomatic plantar callosities under the fourth metatarsal heads. Conclusions: The minimally invasive osteotomy is an effective and reliable technique for the treatment of painful bunionette, and it achieved more than 90% excellent and good results with reduced surgical time and complications.
Surgical Treatment of Hallux Valgus and Forefoot Deformities in Sweden: A Population-Based Study
Authors: Saro Carlos , Bengtsson Ann-Sophie , Lindgren Urban , Adami Johanna , Blomqvist Paul , Felländer-Tsai Li
Published: March 2008

Background: Although surgical correction for hallux valgus and other toe deformities is one of the most common procedures in foot surgery, its incidence in the general population is not well-known. Materials and Methods: The study population comprised patients living in Sweden of a varied age group and both sexes who underwent forefoot surgery. We identified all inpatient cases from 1997 to 2000 and all ambulatory cases in 2000 registered in the National Swedish Patient Register (NSPR). Further, clinical data for the surgical treatment of hallux valgus deformity were extracted from medical records in patients treated in a geographically defined region (Stockholm). Results: In total, 6956 patients with surgically treated forefoot deformities were identified from the adult population, equivalent to a cumulative incidence of 0.8 procedures per 1000 inhabitants for the whole analyzed group. There were regional variations and significant sex differences. The age distribution in both sexes was characterized by a peak in the fifth decade. Forefoot surgery was statistically more frequently performed in private clinics than in public hospitals ( p < 0.001). Hallux valgus surgery was by far the most common procedure regarding forefoot surgery. Conclusion: The prevalence of forefoot- and hallux valgus surgery was not evenly distributed in the six major regions in Sweden. It is more common in urban than in rural regions. Furthermore, forefoot surgery is performed more frequently in private clinics than in community hospitals despite common financial sources.
Synovial Chondromatosis of the Foot and Ankle
Authors: Galat Daniel D. , Ackerman Duncan B. , Spoon Daniel , Turner Norman S. , Shives Thomas C.
Published: March 2008

Background: Synovial chondromatosis (SC) is a benign condition where the synovial lining of joints, bursae, or tendon sheaths undergoes metaplasia and ultimately forms cartilaginous loose bodies. Synovial chondromatosis of the foot and ankle is exceedingly rare, and outcomes following surgical excision are largely unknown. Materials and Methods: An Institutional Review Board-approved retrospective review of our institution's surgical database from 1970 to 2006 revealed 8 patients with SC of the foot and/or ankle confirmed by pathology. Results: Eight patients (4 female and 4 male) presented with pain, locking, or stiffness. Average age at presentation was 37 (range, 19 to 60) years. Average followup was 9.5 (range, 1 to 31) years. Six patients had involvement of the ankle, and two, the midfoot. Four patients underwent ankle synovectomy with loose body removal, and were pain-free at last followup. One patient underwent excision and midfoot arthrodesis for severe midfoot destruction. Three patients ultimately underwent below knee amputation, one for multiple recurrences and two for malignant transformation to low-grade chondrosarcoma. Conclusion: To our knowledge, this is the largest reported series of patients with SC of the foot and ankle. In half the patients, synovectomy with excision of loose bodies resulted in pain free return to normal function, without recurrence, at last followup. However, recurrence occurred in 3 (37.5%) of 8 patients with subsequent malignant transformation to low-grade chondrosarcoma occurring in 2 patients.
Achilles Lengthening/Posterior Tibial Tenotomy with Immediate Weightbearing for Patients with Significant Comorbidities
Authors: Redfern John C. , Thordarson David B.
Published: March 2008

Background: Fixed equinovarus deformities can be challenging to treat especially in medically debilitated patients. The purpose of this study was to evaluate Achilles lengthening with posterior tibial tenotomy and immediate weightbearing in this difficult group of patients. Materials and Methods: Thirteen extremities in 10 patients underwent Achilles lengthening and posterior tibial tenotomy for fixed equinovarus deformities with significant medical comorbidities. Pre- and postoperative ambulatory status and deformities were noted. Results: Average age at the time of surgery was 65 with an average duration of deformity 6.3 years. The average equinus corrected from 26 degrees to 1.2 degrees and the average varus deformity improved from —8.5 degrees to 2.7 degrees. All patients except one who was wheelchair-bound had a significant improvement in ambulatory status. Conclusion: Achilles lengthening with posterior tibial tenotomy allowed for immediate postoperative weightbearing with improvement in deformity and ambulatory status in this complicated patient group.