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Huntington's disease is a progressive, neurodegenerative, and inherited disease. Antioxidants have been shown effective in slowing disease progression in animal models of HD and are under investigation in human clinical trials. α-Pinene, a polyphenolic compound of the terpene family, has been shown to exert antioxidant activity. Therefore, this study aimed to investigate the impact of α-pinene on animal model of HD. Thirty-two male Wistar rats received 3-Nitropropionic acid (3-NP) for induction of the disease model or treated with α-pinene + 3-NP in different groups. Motor skill, and biochemical evaluations to detect oxidant/antioxidant markers in rat cortex and striatum were performed in all groups. We found that α-pinene significantly improved 3-NP-induced changes in the body weight, rotarod activity, time taken to cross the narrow beam, and locomotor activity. Biochemical analysis revealed that α-pinene significantly decreased the 3NP-induced elevation in oxidant markers, nitrite, and malondialdehyde in both cortex and striatum. In addition, α-pinene counteracted the 3NP-induced fall in antioxidant enzymes, including superoxide dismutase, catalase, and glutathione in the cortex and striatum. In conclusion, we found that α-pinene prevented the motor dysfunction induced by 3-NP in the animal model of Huntington’s disease. Oxidants-antioxidant balance might be involved in the protective effect of α-pinene.

We present a rate-independent crystal plasticity theory in the finite deformation range. The formulation revolves around theory of distribution and strong discontinuity concepts applied to the slip systems. Uniform and conforming deformation fields are introduced, from which deformation gradients for the crystal lattice and the crystal itself are derived. For a crystal deforming in single slip, we show that the crystal rotates the active slip system the same way as the lattice does, leading to an elegant and exact stress-point integration algorithm for the overall crystal stresses. For a crystal deforming in multiple slips the crystal no longer rotates the slip systems exactly as the lattice does. For this case, we present a stress-point integration algorithm accounting for the exact push-forward operation induced by the lattice on the active systems. We also consider a simplified stress-point integration algorithm for multislip systems that remains highly accurate for a wide range of stress paths considered. The framework for system activation and the selection of linearly independent slip systems follows a well-established ‘ultimate algorithm’ for rate-independent crystal plasticity developed for infinitesimal deformation.

This study focuses on the implications that the indiscriminate use of empirical shock metrics can have on shock risk assessment of Ball Grid Array (BGA) components in board level tests. Empirical shock metrics discussed are: 1) shock table applied acceleration, 2) top package acceleration and 3) board strain. Computational modeling and fundamental physics considerations were used to prove that the empirical metrics can lead to wrong conclusions about capability of the BGAs and their performance in the field. These empirical metrics can be considered an indirect indicator of solder joint failure, but because there is no universal (setup independent) correlation to solder joint failure, they are not directly transferable. For a metric to be universal it has to have a unique correlation to solder joint damage, i.e. it has to be based on the physics of failure. For the shock failures, such a metric can be solder joint stress or strain. There are two important implications of this study: 1) when indirect metrics are used, the value determined in the system condition should not be directly used as a test condition requirement and 2) BGA capability when measured by indirect metric will vary as a function of board setup. The indirect metrics can still be used, but they must be scaled to account for structural differences among board setups. For that scaling to be valid, it must be rooted in the knowledge of failure physics and the application of physics based metric. The study provides examples on how empirical metrics scaling should be done and discusses the physics behind it.Copyright © 2015 by ASME

The overall elasto-plastic behavior of single crystals is governed by individual slips on crystallographic planes, which occur when the resolved shear stress on a critical slip system reaches a certain maximum value. The challenge lies in identifying the activated slip systems for a given load increment since the process involves selection from a pool of linearly dependent slip systems. In this paper, we use an “ultimate algorithm” for the numerical integration of the elasto-plastic constitutive equation for single crystals. The term ultimate indicates exact integration of the elasto-plastic constitutive equation and explicit tracking of the sequence of slip system activation. We implement the algorithm into a finite element code and report the performance for polycrystals subjected to complicated loading paths including non-proportional and reverse/cyclic loading at different crystal orientations. It is shown that the ultimate algorithm is comparable to the widely used radial return algorithm for J2 plasticity in terms of global numerical stability.

We use crystal plasticity to describe the slip and dislocation in crystalline solids under mechanical loading. The constitutive formulation involves linearly dependent slip systems from which we extract a group of linearly independent slip systems using the ultimate algorithm advocated by Borja and Wren (Int J Numer Methods Eng 36:3815–3840, 1993). We implement the ultimate algorithm into a 3D nonlinear finite element code with infinitesimal deformation. We use the code to compare the deformation fields generated by crystal plasticity formulation and the classic J 2 plasticity model.