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The natural laminar and stable heat and mass convection in an enclosure defined by two horizontal confocal elliptical cylinders with normal and opposite buoyancy forces under uniform concentration and temperature has been numerically explored in this study. The physical Cartesian domain is transformed into an elliptical domain. For the numerical simulation, the equations of conservation of mass, momentum and energy as well as the boundary conditions are discretized by the numerical approach of finite volumes. The algebraic equations obtained were solved by the iterative Gauss-Seidel method. As a function of the effective variables, which are the Rayleigh number, the buoyancy force number N, the Prandtl number, and the Lewis number, the findings are shown as fields of velocities, temperatures, and concentrations as well as the average Nusselt and Sherwood numbers. The results showed that there is a critical buoyancy ratio N cr = −1, where the mean Sherwood and Nusselt number values are minimal. Their values are decreased by rising values of N when N < N cr and raised by rising values of N when N > N cr , and raising the buoyancy ratio N's absolute value results in higher heat and mass transfer characteristics (averages Nusselt and Sherwood numbers). [ABSTRACT FROM AUTHOR]

Sacrococcygeal teratomas (SCTs) are rare congenital tumors that are derived from embryonic germ cell layers [ 1 ]. They are the most common extragonadal germ cell tumors (GCTs) in the neonate, with a reported incidence of 1 in 35 000 births [ 2 ]. Teratomas are made of tissues that derive from three germinal layers (ectoderm, endoderm, and mesoderm). Sacrococcygeal teratomas are more common in girls, with a sex ratio of 1:4 [ 3 ]. The most frequent location of teratoma in children is the sacrococcygeal area [ 4 ]. Many sacrococcygeal teratoma cases are diagnosed prenatally with routine ultrasonography between the 22nd and the 34th week of gestation. However, access to routine prenatal ultrasound in low and middle income countries is limited [ 5 ]. Antenatal diagnosis is essential to the pregnancy management and to prevent neonatal death by identifying fetuses that are at a higher risk of complications and planning an adequate intervention when needed [ 6 ]. This case is reported to describe a North African neonate presenting with a sacrococcygeal teratoma at birth without prior antenatal diagnosis, and highlight the need for prenatal routine care in low and middle income countries. [ABSTRACT FROM AUTHOR]

Abstract: This article is a study, which consists of developing and validating the method of finished differences applied on unstationary thermal conduction with source in a square form oven, and the result is a partial and differential equation with a parabolic type. The method of finished differences is used to solve these equations. 1 iterative method of: GAUSS Seidel. [Copyright &y& Elsevier]

Abstract: We have carried out a first-principles total-energy calculations of the structural and the electronic properties for the series of H-phases compounds Ti2AlC and Ti2AlN. We have applied the full-potential linearized augmented plane waves (FP-LAPW) method based on the density functional theory (DFT) using the local-density approximation (LDA) and/or the generalized gradient approximation (GGA). The quasi-harmonic Debye model, using a set of total energy versus volume calculations obtained with the FP-LAPW method which is applied to study the thermal and vibrational effects. Temperature and pressure effects on the structural parameters, thermal expansions, heat capacities and Debye temperatures are determined from the non-equilibrium Gibbs functions. [Copyright &y& Elsevier]

Pericardial hydatid cyst without cardiac involvement is extremely rare even in endemic countries [ 1 ], it results from the development of the larval form of Echinococcus granulosus tapeworm. Only 2–10% of cardiac echinococcosis are characterized by a pericardial cyst formation [ 2 ]. Clinical presentation usually regroups dyspnea, weakness, unexplained weight loss. When the localization of the cyst is cardiac, the occurrence of tamponade with fatal outcomes may occur if not treated early [ 3 ]. Diagnosis is based on imaging data and assisted by serology. The treatment often combines surgical procedures with medical therapy with albendazole [ 4 ]. The pericardial location makes the surgical treatment more challenging.. We report the clinical observation of a 5 years old operated child. We present the case of a 5 year-old boy whose parents sought medical attention due to dyspnea and abdominal mass. [ABSTRACT FROM AUTHOR]

First-principles calculations are performed to study the structural, electronic and thermodynamic properties of technologically important Cd 1− x Be x Se ternary alloys using the full potential-linearized augmented plane wave method within the density functional theory. We use both PBE and Engel–Vosko generalized gradient approximations of the exchange-correlation energy that are based on the optimization of total energy and corresponding potential, respectively. The ground-state properties are determined for CdSe, BeSe and their mixed crystals at various concentrations ( x =0.25, 0.5, and 0.75). Deviation of the lattice parameter from Vegard׳s law and the bulk modulus from the linear concentration dependence was observed. Using the approach of Zunger and co-workers, the microscopic origins of the band-gap bowing parameter have been explained. Through the quasi-harmonic Debye model, in which the phononic effects are considered, we have determined the thermal properties of the Cd 1− x Be x Se alloy such as the Debye temperature and heat capacities. [ABSTRACT FROM AUTHOR]

In order to develop an innovative, environmentally friendly composite materials for the construction industry, this study aims to exploit three types of waste material to manufacture cement mortars for producing lightweight concretes, ecologically friendly paving slabs and pavers. For this purpose, the response surface methodology (RSM) was investigated to predict and optimize the physical properties of mortars made from dune sand (DS) combined with recycled sand (RS), which are abundant in the desert and considered as waste products, reinforced by polymerized polyethylene terephthalate (PET) fibers of two different lengths, 20 mm and 30 mm, respectively. This investigation was carried out to assess the material's capacity in terms of engineering criteria, including air content in the fresh state (Ac), shrinkage (Sh), flexural displacement (Yf), ultrasonic pulse velocity (UPV), and water absorption (WA). Further, the chemical composition and mineralogical transformations at high temperatures of the produced mortar were examined. The ANOVA analysis of variance and a desirability function (DF) test are developed based on the Box-Behnken Design to predict and optimize variables and output responses by maximizing the mechanical properties and minimizing the physical properties. The obtained results reveal a significant improvement in the physical properties of the mortars, 6.25% Sh, 43% Yf, 4.65% UPV, and 6.54% WA, confirming the beneficial effect of fiber-reinforced products compared with those without fibers. The proposed quadratic model proves the validity of the experimental results with a better accuracy of less than 4.5% error. The optimal formulation obtained in this protocol consisted of 50% DS, 50% RS, and 2% PET, with a length of 12.70 mm. This mix yielded 0.799% Ac, −95.28 μm/m Sh, 5.79 mm Yf, 3855.11 m/s UPV, and 11.91% WA, presenting an attractive option for applications in eco-construction sustainability. Therefore, The RSM model correlates well with the experimental data, which has contributed to an improvement in the physical-mechanical features. Consequently, this eco-mortar has several applications in buildings, roads, bridges, for bending elements (beams, slabs) and can also be used for repairing damaged structures. [Display omitted] • The RSM methodology has been used for the optimization and prediction process. • The three types of waste used DS-RS-PF have proven essential in eco-construction. • The 50/50 sand mixture is relevant for the high quality of the studied mortar. • DS-RS-PF combination decreases Ac, Sh, WA and increases Yf, UPV, showing high behavior. • Abandoned dune sand is considered to be waste. [ABSTRACT FROM AUTHOR]

• Economic valorisation of eco-mortar composed of dune sand, recycled sand and PET-F. • Dune sand corrected by recycled sand with PET-F improves the performance of the eco-mortar. • Dune sand and PET fibre-reinforced prisms enhance flexural strength. • The RSM responses optimally improve the physical–mechanical properties of eco-mortar. • The interaction of DS and RS provides a sustainable solution for eco-mortar production. Today, economic and environmental interests have become imperative in construction works. Therefore, the use of substitute materials for natural aggregates or cement contributes to the preservation of natural resources and the reduction of carbon dioxide diffusion. The large quantity of dune sand available in the Algerian Sahara and the affordable cost of recycled aggregates and plastic waste encourage their use as a replacement for natural aggregates in the production of cementitious materials. The interaction of dune sand (DS) and recycled sand (RS) with the introduction of a polyethylene terephthalate (PET-F) fibre help to design a normative ecological material. The aim of the study was to explore and optimize the proportions of these materials to create an environmentally-friendly cementitious product. The strategy is based on the progressive substitution of dune sand by another originating from demolition waste at different rates: 0%, 25%, 50%, 75% and 100%, and a gradual rate of PET-F fibres, 20 and 30 mm from 0% to 2% with a step of 0.5%. In this article, we study the effect of the new composites on the physico-mechanical performance of the designed eco-mortars through several tests (spreadability, fresh density, porosity, capillary and immersion absorption, compression strength, and flexural strength). In addition, we utilise Response Surface Methodology (RSM) to predict approximate parameters that influence the properties of new cementitious composites. The results obtained show the significant benefit of the following rates: 50% SD, 50% SR and (0.5%, 30 mm) PET-F fibre. Thus, the RSM model correlates well with the experimental data, which has undoubtedly led to an improvement in the physical–mechanical characteristics of the eco-mortar studied. Otherwise, the proposed model reaches a high pertinence, with a good desirability coefficient of 0.917. [ABSTRACT FROM AUTHOR]

In this work the static behavior of magnetorheological elastomer (MRE) sandwich beams is studied in flexion with transverse shear. The beam is formed by two aluminum skins bonded to a core of elastomeric silicone oil and loaded with iron particles at 30%. The rigidity of the beam is given by the addition of a usual stiffness matrix of two aluminum skins and an MRE complex stiffness matrix. The latter is a function of the magnetorheological properties of the MRE. The results show the influence of MRE adaptive stiffness and the loss factor in the static behavior of the sandwich studied. The structure proposed can be directly applied to civil engineering, for example, building foundations, mechanical engineering and aircraft wings. [ABSTRACT FROM AUTHOR]

This study presents the static and vibratory behavior of a hybrid sandwich plate with a magnetorheological elastomer core. In order to improve the static and vibrational behavior of the plate, the pseudo-fibers formed by the effect of the magnetic field on the elastomer charged by the ferromagnetic particles are oriented at 45° with respect to the direction of the magnetic field at 0°. Ritz's approach is taken to solve the physical problem. In order to verify and compare the results obtained by the Ritz approach, an analysis using the finite element method was carried out. The effect of the magnetic field on bending displacements, normal stresses, shear stresses, and static strain modes of the off-axis anisotropic hybrid sandwich plate are discussed. The rheological property of the MRE material at 0° and at 45° are determined experimentally, and are exploited in the two numerical approaches. The natural frequencies and the modal damping of the sandwich plate are calculated and discussed for various magnetic field intensities. The results obtained by the two methods are compared. These off-axis anisotropic MRE structures could open up new opportunities in various fields of aeronautics, aerospace, mechanical engineering and civil engineering. [ABSTRACT FROM AUTHOR]