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INTRODUCTION: pigmented villonodular synovitis (PVNS) is a benign condition that affects the knee, leading to abnormal proliferation of the synovial membrane and the accumulation of hemosiderin in the joint cavity. Although it can be surgically treated, PVNS tends to have a high recurrence rate, potentially resulting in chronic joint damage. CASE REPORT: we present the case of a young woman who experienced localized pain in her right knee due to a recurrence of PVNS. Magnetic resonance imaging revealed multiple multilobulated cystic lesions affecting the entire joint, including the ligaments. The patient underwent open surgical resection with a favorable clinical outcome. Histopathological examinations confirmed the absence of malignancy. CONCLUSION: while arthroscopy is typically the preferred treatment for PVNS, this case highlights the tendency for recurrence associated with this approach. Open surgical resection, supported by benign histopathological findings in this case, suggests a favorable long-term prognosis.
INTRODUCCIÓN: la sinovitis villonodular pigmentada (SVNP) es una enfermedad benigna que afecta la articulación de la rodilla, que causa una proliferación anormal de la membrana sinovial y la acumulación de hemosiderina en la cavidad articular. A pesar de que es posible tratarla mediante cirugía, la SVNP tiende a tener una alta tasa de recurrencia, lo que puede resultar en daño articular crónico. REPORTE DEL CASO: se presenta el caso de una mujer joven que experimentó dolor localizado en la rodilla derecha debido a una recurrencia de SVNP. La resonancia magnética reveló múltiples lesiones quísticas multilobuladas que afectaban a toda la articulación, incluyendo los ligamentos. La paciente fue sometida a una resección quirúrgica abierta, con una evolución clínica favorable. Los exámenes histopatológicos confirmaron la ausencia de malignidad. CONCLUSIÓN: aunque la artroscopía se considera el tratamiento de elección para la SVNP, este caso ilustra la tendencia a la recurrencia asociada con este enfoque. La resección quirúrgica abierta, respaldada por los hallazgos histopatológicos benignos en este caso, sugiere un pronóstico favorable a largo plazo.
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Recidiva , Sinovite Pigmentada Vilonodular , Humanos , Sinovite Pigmentada Vilonodular/cirurgia , Feminino , AdultoRESUMO
The number of publications related to the implementation of nanotechnology in the construction industry, and specifically to the application of nanosilica (SiO2), has had a constant increase in recent years. Based on this, in the present work, an analysis was carried out using bibliometric techniques, with the aim at characterizing the development of specialized literature and identifying the largest areas of growth in the field, maintaining hydrophobic nanosilica as the research guideline. This analysis acquired information from the Scopus and Web of Science (WoS) databases to compare bibliometric indicators of the publications. It should be noted that, even though bibliometric analysis is useful to identify the study areas of greatest interest, to complement this work, the implementation of a method that helped in the research process to obtain the most important bibliography was required. This study implemented Methodi Ordinatio, which helped to take a new direction. Therefore, based on this method, a list of articles cataloged and ranked is obtained, which is the basis for integrating the final bibliographic portfolio. â¢The study applies the Methodi Ordinatio to obtain a portfolio of the most relevant articles to guide the researchers' work.â¢Insightful information can be obtained using VOSviewer to analyze and visualize metadata of the bibliographic portfolio.â¢The study demonstrates how the alpha value in the InOrdinatio formula modifies the resulting portfolio.
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Based on the stochastic Langevin equation, we derived the total friction experienced by a tracer particle diffusing in thermally equilibrated colloidal magnetic fluids. This transport property leads to new expressions for its long-time diffusion coefficients, which satisfy an Einstein relation with the frictions of its translational and rotational Brownian motion. Further use of the nano-rheology theory allowed us to derive also the viscoelastic modulus of the colloid from such a property. The temporal relaxation of the viscoelasticity and transport coefficient turns out to be governed by the intermediate scattering function of the colloid. We derived an explicit formula for this evolution function within a hydrodynamic theory to include rotational degrees of freedom of the particles. In the limit of short frequencies, the viscous moduli render a new expression for the static viscosity. We found that its comparison with known experiments, at low and high concentration of ferroparticles in magnetite ferrofluids, is fair. However, comparing the predicted viscoelastic moduli with computer simulations as a function of frequency yields poor agreement.
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The parametric instability in nematic liquid crystal layers has been studied using linear stability theory. Using material parameters of typical nematics, the neutral stability curve and dispersion relation of a system that presents critical subharmonic waves is obtained. The critical acceleration and wave number of the unstable stationary waves are discontinuous at the nematic-isotropic transition temperature and conform to similar sharp changes experienced by the viscosities and surface tension as a function of temperature. Due to Marangoni flow the curve of the critical acceleration as a function of excitation frequency exhibits a minimum. If the Marangoni flow is neglected and the dynamical viscosity is increased, a monotonously increasing dependence of the acceleration in terms of oscillation frequency is observed. A bicritical instability is reached for a layer thickness of a few millimeters. A well-defined subharmonic wave is attained when the thickness of the layer is further increased. The dispersion relation of these waves displays a discontinuous shift at high frequencies due to alternating secondary thresholds of Faraday waves. At negligible external forcing we determined the dispersion relationship of thermal surface waves.
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We studied with linear stability analysis the onset of parametric waves on the surface of a smectic A liquid crystal. For thin Sm-A layers under an applied static magnetic field there are subharmonic-harmonic branches of surface waves at low modulating frequency of the driving acceleration and long wavelength. A semi-infinite Sm-A medium poses a dispersion relation with similar trends as for Newtonian liquids. When the external forcing is negligible there are two damped surface waves excited by thermal fluctuation of the interface, whereas in the absence of a magnetic field the dominant modes are of harmonic type for typical material parameters.
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The interaction of two oppositely highly charged surfaces in an electrolyte solution and the number of released counterions from the slit between the surfaces were studied in terms of the anisotropic hypernetted chain and nonlinear Poisson-Boltzmann theories. Liquid theory predictions of the attractive pressure and release of counterions between the plates are larger than those of the mean field approach at low and moderate concentration of added salt. Further, at high salt concentration there is an opposite relationship of the two theories in their numerical results for the attractive pressure for all surface separations. These deviations of the predicted equilibrium properties arise both from the charge density and the ion size correlation effects included in hypernetted chain theory.
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We have studied theoretically the compressibility modulus B of DNA and complexation adsorption isotherms of DNA and lipids, as a function of DNA spacing d(DNA) and NaCl electrolyte concentration, respectively, in isoelectric states of lamellar DNA/cationic lipid (CL) self-assemblies. The electrostatic free energy derived from the Poisson-Boltzmann theory predicts partial agreement with measured B values for interhelical separations d(DNA)>33 A when use is made of a fit of hydration repulsion from bulk DNA hexagonal phases in solution. For lower interchain separations the prediction worsens due to the hydration interaction that overcomes the electrostatic contribution. An exact match of the system's counterion electrochemical potentials and the coions of salt in aqueous phase leads to the electrostatic part of the free energy that renders isotherms of d(DNA) versus ionic strength in qualitative consistency with general trends of available experimental data of CL-DNA complexes.
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Biofísica/métodos , DNA/química , Eletroquímica/métodos , Lipídeos/química , Adsorção , Entropia , Íons , Focalização Isoelétrica , Substâncias Macromoleculares , Modelos Estatísticos , Conformação Molecular , Conformação de Ácido Nucleico , Eletricidade Estática , Termodinâmica , Água/químicaRESUMO
Long-time self-diffusion coefficients of ferrofluid suspensions are derived from an effective Langevin equation approach. The dependences of these transport properties on the volume fraction of particles and the strength of interparticle interaction are investigated. Strong reduction of the rotational and the translational Brownian motion of the particles is manifested upon increase of particle-particle interaction or ferrofluid concentration.
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The total force between two like charged surfaces is investigated as a function of counterion concentration in aqueous solution and surfaces distance of separation. A smooth and a discrete density of surface charge sigma(s) lead to differences in the force distance curve at high sigma(s), which are negligible for low surface charge. The total force per unit area with divalent counterions is an oscillating function of sigma(s). At fixed surfaces separation and region of attraction (increasing sigma(s)), there is a variation in its strength that results from a competition between the ideal kinetic and ion-ion correlation force components as predicted from the anisotropic hypernetted chain approximation.