Spherical agarose-coated magnetic nanoparticles functionalized with a new salen for magnetic solid-phase extraction of uranyl ion

The authors describe a method for magnetic solid phase extraction of uranyl ions from water samples. It is based on the use of spherical agarose-coated magnetic nanoparticles along with magnetic field agitation. The salen type Schiff base N,N’-bis(4-hydroxysalicylidene)-1,2-phenylenediamine was synthesized from resorcinol in two steps and characterized by infrared and nucleic magnetic resonance spectroscopies. The particles were then activated by an epichlorohydrin method and functionalized with the Schiff base which acts as a selective ligand for the extraction of UO₂(II). Following preconcentration and elution with HCl, the ions were quantified by spectrophotometry using Arsenazo III as the indicator. The effects of pH value, ionic strength and amount of the adsorbent on the extraction of UO₂(II) were optimized by a multivariate central composite design method. Six replicate analyses under optimized conditions resulted in a recovery of 96.6 % with a relative standard deviation of 3.4 % for UO₂(II). The detection limit of the method (at a signal-to-noise ratio of 3σ) is 10 μg L￣¹. The method was successfully applied to the determination of UO₂(II) in spiked water samples.

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Graphical Abstract Spherical agarose-coated magnetic nanoparticles (SACMNPs) were prepared in the presence of Span 85 (a nonionic surfactant) and functionalized by a salen type Schiff base for magnetic solid-phase extraction of uranyl ion

     

A computational framework for fluid–porous structure interaction with large structural deformation

We study the effect of poroelasticity on fluid–structure interaction. More precisely, we analyze the role of fluid flow through a deformable porous matrix in the energy dissipation behavior of a poroelastic structure. For this purpose, we develop and use a nonlinear poroelastic computational model and apply it to the fluid–structure interaction simulations. We discretize the problem by means of the finite element method for the spatial approximation and using finite differences in time. The numerical discretization leads to a system of non-linear equations that are solved by Newton’s method. We adopt a moving mesh algorithm, based on the Arbitrary Lagrangian–Eulerian method to handle large deformations of the structure. To reduce the computational cost, the coupled problem of free fluid, porous media flow and solid mechanics is split among its components and solved using a partitioned approach. Numerical results show that the flow through the porous matrix is responsible for generating a hysteresis loop in the stress versus displacement diagrams of the poroelastic structure. The sensitivity of this effect with respect to the parameters of the problem is also analyzed.

     

Thermomechanical behavior of shape memory polymer beams reinforced by corrugated polymeric sections

With the ever-increasing applications of smart actuators, great attention is drawn to the SMP-based composites. In this paper the flexural behavior of corrugated SMP composite beams is studied. Employing a widely-accepted one-dimensional SMP model, based on the assumptions of Euler–Bernoulli beam theory, the governing equations are obtained. Further using a finite difference scheme the equations are solved. In this regard, different types of corrugated sections (rectangular, sinusoidal, …) with equal SMP content are studied and the mechanical properties of interest (load capacity, shape fixity, …) are compared. It is observed that reinforced single-cell patterns have completely different mechanical behaviors. For the sake of generality, the single-cell reinforced composite sections are studied in detail. Numerical results show an increase in load capacity of the structure. However, like any other reinforcing method, an inevitable small decrease in shape fixity is observed. In addition to the properties studied here, other desirable characteristics can be achieved by introducing a reinforcing cover. The results can be utilized in designing SMP-based actuators since the present work proposes a simple and efficient method for enhancing the load capacity of the SMP-based composites.