Late Embryogenesis Abundant (LEA) proteins are mostly predicted to be intrinsically disordered proteins (IDPs) that are induced under conditions of cellular dehydration. Their functions, however, are largely unexplored and also their structure and interactions with potential target molecules have only recently been investigated in a small number of proteins. Here, we have characterized the wheat LEA protein TdLEA3, which has sequence homology with the group of LEA_4 proteins that are characterized by the 11-mer repeat motif TAQAAKEKAXE. TdLEA3 has five repeats of this imperfectly conserved 11-mer amino acid motif. To investigate the structure of the protein, we used circular dichroism (CD) and Fourier-transform infrared (FTIR) spectroscopy. The data show that TdLEA3 was largely disordered under fully hydrated conditions and acquired α-helical structure upon drying and in the presence of trifluoroethanol (TFE). Moreover, the addition of increasing glycerol concentrations to the protein solution induced a progressive gain in α-helix content. Activity assays indicated that TdLEA3 was able to prevent the inactivation of lactate dehydrogenase (LDH) under heat, dehydration-rehydration and freeze-thaw treatments. In addition, TdLEA3 reduced aggregate formation in the enzyme during these treatments.

In this paper, a geometrically nonlinear analysis of functionally graded material (FGM) shells is investigated using Abaqus software. A user defined subroutine (UMAT) is developed and implemented in Abaqus/Standard to study the FG shells in large displacements and rotations. The material properties are introduced according to the integration points in Abaqus via the UMAT subroutine. The predictions of static response of several non-trivial structure problems are compared to some reference solutions in order to verify the accuracy and the effectiveness of the new developed nonlinear solution procedures. All the results indicate very good performance in comparison with references. Lee et al. 2009). Typically, FG shell structures were presented using: (i) Kirchhoff-Love theory, Chi and Chung (2006), where the shear strains are assumed zero, which is not acceptable for FG shell; (ii) the First-order Shear Deformation Theory (FSDT) (Praveen and Reddy 1998;Thai and Kim 2015), which gives a correct overall assessment. Notice that the shear correction factors should be incorporated to adjust the transverse shear stiffness; (iii) the High-order Shear Deformation Theory (HSDT) (Neves et al. 2012;Wali et al. 2014Wali et al. , 2015Frikha et al. 2016) in which the equations of motion are more complicated to obtain than those of the FSDT; among other theories. KeywordsIt is certainly plausible that linear finite element (FE) models cannot be able to accurately predict the structural response presenting large elastic deformations and finite rotations. Indeed, according to Yu et al. (2015), several practical problems of FG structures require a geometrically non-linear formulation, such as the post-buckling behavior of structures used in aeronautical, aerospace as well as in mechanical and civil engineering. In such cases, it becomes crucial to develop efficient and accurate nonlinear FE models.It is well known that analytical solutions of shell problems are very limited. Hence, most of reference solutions are previously reported numerical solutions. Particularly, for FE geometric nonlinear analysis of FG shells, several research papers are surveyed (Praveen and Reddy 1998;Reddy 2000;Kattimani and Ray 2015;Duc et al. 2017; Reddy 2007a, 2007b;Alinia and Ghannadpour 2009;Phung-Van et al. 2014;Kim et al. 2008;Hajlaoui et al. 2017;Frikha and Dammak 2017;Asemi et al. 2014 andAnsari et al. 2016). In these references, a number of theoretical formulation and finite element models based on von Karman, Kirchhoff-Love, FSDT and HSDT theories were proposed to study the geometrically non-linear behavior of FGMs Structures.Hosseini Kordkheili and Naghdabadi (2007) derived a FE formulation for the geometrically nonlinear thermoelastic analysis of FGM plates and shells using the updated Lagrangian approach. Later, Zhao and Liew (2009) conducted a geometrically non-linear analysis of FGM shells under mechanical and thermal loading using the element-free kp-Ritz method. The formulation was based on the modified version of Sander's non-li...

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Pultrusion is a crucial method for continuous production of fiber-reinforced composites. It was developed several years ago for thermosetting polymer matrices, but the challenge is now to extend it to thermoplastic matrices, with a much higher viscosity. In this paper, we propose an analysis of the parameters influencing fiber impregnation in the conditions of this process. A semi-analytical one-dimensional axisymmetric model based on Darcy’s law and Stokes equations is developed to predict the impregnation profile inside the fibrous phase in the case of a natural impregnation governed by capillary forces. Thanks to a dimensional analysis, it enables to quantify the influence of all the material and testing parameters under the assumption of a slow variation of the geometry of the impregnation die. The cases of a straight and conical dies are discussed. For the first case, an exhaustive numerical study enables to define the optimal processing conditions for a perfect impregnation. Those results are shown to be useful tools for finding an optimal pulling velocity and die length for a given fluid/fibers pair. For the second case, we show that section reductions do not improve impregnation.