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This paper investigates the nonlinear dynamic deflection, natural frequency, and wave propagation in functionally graded (FG) porous piezoelectric microscale tubes under periodic load, hygrothermal conditions, and an external electric field. The piezoelectric material used to make the smart microtubes has pores that may be smoothly changed or uniformly distributed over the tube wall. Here, three types of porosity distribution are taken into consideration. The nonlinear motion equations are constructed using a novel shear deformation beam theory and the modified couple stress theory (MCST). The nonlinear motion equations are solved using the fourth-order Runge–Kutta technique and the Galerkin approach. The effects of various geometric parameters, porosity distribution type, porosity factor, periodic load amplitude and frequency, material length scale parameter, moisture, and temperature on the nonlinear dynamic deflection, natural frequency, and wave frequency of FG porous piezoelectric microtubes are explored through a number of parametric investigations. [ABSTRACT FROM AUTHOR]

Abstract Background Hepatitis B virus (HBV) may reactivate when treating chronic hepatitis C (CHC) with direct-acting antivirals (DAA). We aimed to investigate the risk of HBV infection and reactivation during DAA therapy by performing a prospective observational study carried on 200 patients positive for chronic HCV who were candidates for treatment by DAA therapy according to the Egyptian guidelines from February 2019 to December 2019; the patients identified to carry HBsAg at baseline or with positive HBc Abs were further assessed for other HBV markers: hepatitis B e antigen at baseline, and serum HBV DNA quantitative measurement at baseline, week 4 of treatment, end of treatment. On the other hand, recent infection by HBV among those patients was observed. Results Of all participants, 49% were males and 51% were females, aged above 18 years. There is a highly statistically significant difference (p-value 1000 IU/L above the baseline level). In addition, 3 new cases acquired recent infection with the positivity of HBc IgM and detectable levels of HBV DNA. After 3 months of study, reactivation was detected in one patient with co-infection (where increased HBV DNA > 1000 IU/L above the baseline level), and 5 new cases acquired recent infection late in the study. Conclusion Screening for HBV infection prior to DAA therapy is required to detect recent infection of reactivation of previous infection during or after DAA therapy.

Nonlinear bending of functionally graded metal/graphene (FGMG) sandwich rectangular plate with metal foam core resting on nonlinear elastic foundations is elucidated in this article. A new shear deformation plate theory is presented to formulate the displacement field. The nonlinear partial differential equations considering the small size effect are established via the principle of virtual work. The nonlinearity is considered by using Von Karman's strain-displacement relations. While, the size effect is captured by employing the modified couple stress theory. The upper and lower layers are made of aluminum as a matrix that reinforced with graphene platelets (GPLs). The GPLs are functionally graded through the thickness of the face layers according to a new cosine rule. Moreover, the metal foam core is also made of aluminum containing porosities that uniformly distributed or functionally graded through the core thickness. The governing equations are solved based on the Galerkin and Newton's methods. The obtained results are examined by introducing some comparison examples. In addition, several parametric examples are discussed including the effects of the porosity type, GPLs distribution type, core-to-face thickness, elastic foundation stiffness, side-to-thickness ratio, plate aspect ratio and material length scale parameter on the nonlinear deflection and stresses of FGMG sandwich plate with metal foam core. [ABSTRACT FROM AUTHOR]

The present work strives to explore some qualitative analysis for the governing equation describing the dynamic response of a piezoelectro-magnetic circular rod. As a result of the integrability study of the governed equation, which furnishes valuable insights into its structure, solutions, and applications in various fields, we apply the well-known Ablowitz–Ramani–Segur (ARS) algorithm to prove the non-integrability of the governed equation in a Painlevé sense. The qualitative theory for planar integrable systems is applied to study the bifurcation of the solutions based on the values of rod material properties. Some new solutions for the governing equation are presented and they are categorized into solitary and double periodic functions. We display a 3D representation of the solutions in addition to investigating the influence of wave velocity on the obtained solution for the particular material of the rod. [ABSTRACT FROM AUTHOR]