One of the challenging issues in additive manufacturing (AM) oriented topology optimization is how to design structures that are self-supportive in a manufacture process without introducing additional supporting materials. In the present contribution, it is intended to resolve this problem under an explicit topology optimization framework where optimal structural topology can be found by optimizing a set of explicit geometry parameters. Two solution approaches established based on the Moving Morphable Components (MMC) and Moving Morphable Voids (MMV) frameworks, respectively, are proposed and some theoretical issues associated with AM oriented topology optimization are also analyzed. Numerical examples provided demonstrate the effectiveness of the proposed methods.

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Summary With the fast development of additive manufacturing technology, topology optimization involving multiple materials has received ever increasing attention. Traditionally, this kind of optimization problem is solved within the implicit solution framework by using the Solid Isotropic Material with Penalization or level set method. This treatment, however, will inevitably lead to a large number of design variables especially when many types of materials are involved and 3‐dimensional (3D) problems are considered. This is because for each type of material, a corresponding density field/level function defined on the entire design domain must be introduced to describe its distribution. In the present paper, a novel approach for topology optimization with multiple materials is established based on the Moving Morphable Component framework. With use of this approach, topology optimization problems with multiple materials can be solved with much less numbers of design variables and degrees of freedom. Numerical examples provided demonstrate the effectiveness of the proposed approach.

Propofol is currently one of the most widely used intravenous anesthetics and has been indicated to induce cognitive dysfunction in adults. Here, we investigated the effects of propofol exposure during early postnatal life on hippocampal neurogenesis. Propofol (30 or 60 mg/kg) was administered to mice on either postnatal day (P) 7 or P7-P9; cell proliferation and neurogenesis in the dentate gyrus (DG) were evaluated on P8 or P17. It showed that exposure to propofol on P7 decreased hippocampal cell proliferation as indicated by BrdU and Sox2 immunostaining at P8 in propofol treatment at the dosage of 60 mg/kg but not at the dosage of 30 mg/kg. Western blots revealed propofol treatment decreased Akt or extracellular signal-related kinase (ERK) 1/2 phosphorylation in the hippocampus at P8. Propofol treatment on P7 to P9 reduced the numbers of newly formed neurons in the DG at P17, which was accompanied by delay of granule neuron maturation and decreased the density of dendritic spines, particularly the mushroom-shaped mature spines. Furthermore, the in vitro findings indicated propofol suppressed cell proliferation and cell mitosis and activated apoptosis of C17.2 neural stem cell line in a dose-dependent manner. These findings suggest that propofol impairs cell proliferation and inhibits neurogenesis in the immature mouse brain and thus is possibly involved in the cognitive dysfunction induced by propofol anesthesia.

With the fast development of Internet and rapid acceptance of Web Service technology, more and more service resources have emerged. Service composition which integrates the functionalities of different services is a promising technique for developing applications across multiple organizations. However, in a distributed, dynamic and autonomous environment, such as a service composition-based system, the availability and reliability are big concerns in terms of nonfunctional properties.In this paper, we propose a novel service composition method, ANGEL, with the target of the improvement of system availability. We adopt redundant mechanism in ANGEL and propose a model to improve the property of the service availability. We model the multiple services selection problem based on redundant mechanism as a nonlinear mixed integer programming problem and therefore, we propose two heuristic algorithms to select multiple feasible services that have the same functions, but with better availability. In order to maintain the availability of composite services, we further introduce monitor and detection mechanisms. Through the comprehensive experiments, we find that our proposed techniques can indeed achieve better availability as expected.