On the Generalization of Reissner Plate Theory to Laminated Plates,Part II: Comparison with the Bending-Gradient Theory

In the first part of this two-part paper (Lebée and Sab in On the generalization of Reissner plate theory to laminated plates, Part I: theory, doi: 10.1007/s10659-016-9581-6, 2015), the original thick plate theory derived by Reissner (J. Math. Phys. 23:184–191, 1944) was rigorously extended to the case of laminated plates. This led to a new plate theory called Generalized-Reissner theory which involves the bending moment, its first and second gradients as static variables. In this second paper, the Bending-Gradient theory (Lebée and Sab in Int. J. Solids Struct. 48(20):2878–2888, 2011 and 2889–2901, 2011) is obtained from the Generalized-Reissner theory and several projections as a Reissner–Mindlin theory are introduced. A comparison with an exact solution for the cylindrical bending of laminated plates is presented. It is observed that the Generalized-Reissner theory converges faster than the Kirchhoff theory for thin plates in terms of deflection. The Bending-Gradient theory does not converge faster but improves considerably the error estimate.     

Discrete and continuous models for in plane loaded random elastic brickwork

The aim of this paper is to study non-periodic masonries – typical of historical buildings – by means of a perturbation approach and to evaluate the effect of a random perturbation on the elastic response of a periodic masonry wall. The random masonry is obtained starting from a periodic running bond pattern. A random perturbation on the horizontal positions of the vertical interfaces between the blocks which form the masonry wall is introduced. In this way, the height of the blocks is uniform, while their width in the horizontal direction is random. The perturbation is limited such as each block has still exactly 6 neighboring blocks. In a first discrete model, the blocks are modeled as rigid bodies connected by elastic interfaces (mortar thin joints). In other words, masonry is seen as a “skeleton” in which the interactions between the rigid blocks are represented by forces and moments which depend on their relative displacements and rotations. A second continuous model is based on the homogenization of the discrete model. Explicit upper and lower bounds on the effective elastic moduli of the homogenized continuous model are obtained and compared to the well-known effective elastic moduli of the regular periodic masonry. It is found that the effective moduli are not very sensitive to the random perturbation (less than 10%). At the end, the Monte Carlo simulation method is used to compare the discrete random model and the continuous model at the structural level (a panel undergoing in plane actions). The randomness of the geometry requires the generation of several samples of size L of the discrete masonry. For a sample of size L, the structural discrete problem is solved using the same numerical procedure adopted in [Cecchi, A., Sab, K., 2004. A comparison between a 3D discrete model and two homogenized plate models for periodic elastic brickwork, International Journal of Solids Structures 41 (9–10), 2259–2276] and the average solution over the samples gives an estimation which depends on L. As L increases, an asymptotic limit is reached. One issue is to find the minimum size for L and to compare the asymptotic average solution to the one obtained from the continuous homogenized model.     

Characterization of hdpe/ha Composites Treated with Titanate and Zirconate Coupling Agents

The development of new materials for bone substitution has been of great interest for the scientific community in the last years. High-density polyethylene (HDPE) and hydroxyapatite (HA) composites have been used in biomedical applications without any inflammatory response. However, the differences in nature of both materials have motivated the use of coupling agents to improve their interfacial interactions. In this work, the effects of adding three different commercial coupling agents (NZ12, Lica01, Lica12) to high-density polyethylene (HDPE)/hydroxyapatite (HA) composites were studied. Composites containing 20 parts per hundred (phr) of HA previously treated with the already mentioned coupling agents were characterized by mechanical tests and their morphologies were analyzed afterwards. Composites with 0.3 and 0.5 wt% of NZ12 unfolded an increase in their Young's modulus and tensile strength, as a consequence of an improved dispersion of the filler into the polymeric matrix. Analysis of the samples by XPS showed that the zirconate coupling agent interacted more with the HA, as reflected in the lower binding energies of the corresponding oxygen atoms, which agrees with their better performance from the mechanical point of view.     

A Potentiometric and Spectroscopic Study on the Interaction Between Human Immunoglobulin G and Sodium Perfluorooctanoate in Aqueous Solution

The interaction between human immunoglobulin G (IgG) and sodium perfluorooctanate (SPFO) has been characterized by a combination of UV-vis and UV-CD spectroscopies and ion selective electrodes. The study determined that there were true specific unions between SPFO and IgG. The conformational changes at the bulk solution, induced by SPFO, were well characterized by UV-vis and UV-CD spectroscopies. Chemical and thermal unfolding were analysed and the thermodynamic parameters were determined.     

Sorption of 60Co(II) from aqueous solutions onto biosynthesized zinc oxide nanocomposites

Journal of Radioanalytical and Nuclear Chemistry - Nano ZnO is biosynthesized using Lactobcillus sp. Poly Acrylic acid-co-Acrylonitrile/ZnO, PAACAN/ZnO, and poly Acrylic acid-co-Maleic acid/ZnO,...     

Extraction and determination of trace amounts of gold(III), palladium(II), platinum(II) and silver(I) with the aid of a magnetic nanosorbent made from Fe3O4-decorated and silica-coated graphene oxide modified with a polypyrrole-polythiophene copolymer

Microchimica Acta - The authors describe the synthesis of a nanosorbent for fast magnetic solid phase extraction of trace levels of Ag(I), Au(III), Pd(II) and Pt(II). It consists of graphene oxide...