Determining patterns in thermoelastic interaction between a crack and a curvilinear inclusion located in a circular plate

A two-dimensional mathematical model of the thermoelastic state has been built for a circular plate containing a curvilinear inclusion and a crack, under the action of a uniformly distributed temperature across the entire piece-homogeneous plate. Using the apparatus of singular integral equations (SIEs), the problem was reduced to a system of two singular integral equations of the first and second kind on the contours of the crack and inclusion, respectively. Numerical solutions to the system of integral equations have been obtained for certain cases of the circular disk with an elliptical inclusion and a crack in the disk outside the inclusion, as well as within the inclusion. These solutions were applied to determine the stress intensity coefficients (SICs) at the tops of the crack. Stress intensity coefficients could later be used to determine the critical temperature values in the disk at which a crack begins to grow. Therefore, such a model reflects, to some extent, the destruction mechanism of the elements of those engineering structures with cracks that are operated in the thermal power industry and, therefore, is relevant. Graphic dependences of stress intensity coefficients on the shape of an inclusion have been built, as well as on its mechanical and thermal-physical characteristics, and a distance to the crack. This would make it possible to analyze the intensity of stresses in the neighborhood of the crack vertices, depending on geometric and mechanical factors. The study's specific results, given in the form of plots, could prove useful in the development of rational modes of operation of structural elements in the form of circular plates with an inclusion hosting a crack. The reported mathematical model builds on the earlier models of two-dimensional stationary problems of thermal conductivity and thermoelasticity for piece-homogeneous bodies with cracks.

Chloroquine- and Hydroxychloroquine–Induced Cardiomyopathy: A Case Report and Brief Literature Review

Objectives To present an index case and review the histologic and electron microscopic findings in chloroquine (CQ) and hydroxychloroquine (HCQ) myopathy, focusing primarily on cardiomyopathy. CQ and HCQ are antimalarial drugs with disease-modifying activity in rheumatic diseases (DMARD) and now are among the most widely used DMARDs. Although they are rare, severe adverse effects caused mainly by deposition of intracellular metabolites in both cardiac and skeletal muscle have been described. Currently, both CQ and HCQ have been proposed to have efficacy for patients with coronavirus disease 2019, and several large centers in the United States and other countries have started clinical trials. Methods A case of HCQ cardiotoxicity diagnosed on an endomyocardial biopsy is presented. A review of the pathology archives was performed to identify additional cases of CQ or HCQ myopathy, and histologic changes were recorded. A brief literature review with an emphasis on pathologic findings in myopathies was performed. Results Including the index case, 4 cases of CQ or HCQ myopathy were identified. Light microscopic findings included vacuolated myopathy, and electron microscopic findings included myeloid bodies and curvilinear inclusion bodies. Conclusion CQ and HCQ myopathy can present following long-term administration of the drug. The pathologic findings are nonspecific and overlap with other vacuolated myopathies, necessitating careful correlation of the histologic changes with the patient’s medical history.

A Rare Case Report of Siblings with Infantile and Late Infantile Forms of Neuronal Ceroid Lipofuscinoses

Neuronal Ceroid Lipofuscinoses is a neurodegenerative disorder predominantly involving grey matter. The 4 classic forms are Infantile type, Late Infantile type, Juvenile type and Adult type. We present a case of 3 siblings of unrelated parents where the eldest had Infantile form of NCL, the second child had Late Infantile Form, and the third child is normal. Both children having different phenotypic presentations have curvilinear inclusion bodies on EM of axillary skin biopsy, low levels of tripeptidyl amino peptidase 1(TPP1) and normal levels of palmitoyl protein thioesterase 1(PPT1), a finding classically present in the Late Infantile variety involving CLN2 mutation. After extensive search we failed to find a case report describing a similar finding. DOI: http://dx.doi.org/10.3126/jnps.v33i3.7924 J. Nepal Paediatr. Soc. 2013;33(3):220-222

Excitation of shear waves in a piezoceramic medium with partially electrodized tunnel openings strengthened by a rigid stringer

An antiplane mixed boundary electroelasticity of a stationary wave process in an unbounded piezoceramic medium containing tunnel heterogeneities of opening or thin rigid inclusion (stringer) type is considered. The excitation of an electric field occurs at the expense of differences of electric potentials applied to the system of electrodes located on a free from stresses opening surface. Using the correct integral representations of the solutions, the boundary problem is reduced to the system of singular integrodifferential equations of the second type with resolvent kernels. The results of the parametric investigations characterizing the behavior of the components of an electroelastic field in the medium area and on the opening surface are given. A system of singular integrodifferential equations is obtained for investigation of a conjugated electroelastic field in a piezomedium with a tunnel along the material axis opening a rigid curvilinear inclusion, excited by a system of active electrodes, located on the opening surface. The solvable system of equations of the boundary problem is reduced to two differential equations of Helmhöltz and Laplace with respect to the amplitude of shear displacement and some auxiliary functions. The obtained system is solved numerically by a special scheme of the method of quadrature.

Two-Phase Potentials for the Treatment of an Elastic Inclusion in Plane Thermoelasticity

A solution to the uncoupled two-dimensional steady-state heat conduction and thermoelastic problems of an elastic curvilinear inclusion embedded in an elastic matrix, with different thermomechanical properties, is provided. The proposed analysis describes the heat conduction problem in terms of one holomorphic complex potential and the thermoelastic problem in terms of two holomorphic potentials; known hereafter as two-phase potentials. The general results of the developed analysis are applied to specific examples and explicit forms of the solution are obtained. It is shown that a uniform heat flow at infinity induces a linear stress distribution within the elliptic inclusion.