摘要：Symmetry and pattern are valuable forms of beauty that can be cherished on both the macroscopic and molecular levels. Scientists have always appreciated the intimate connections between symmetry and molecular structures, which is reflected in their design of highly symmetrical compounds.

摘要：The disposal of spent nuclear fuel is a long-standing issue in nuclear ***,UO_2 and metallic U arc used as a fuel in nuclear *** nuclear fuel contains fission products and transuranium elements,which would remain radioactive for 10~4 to 10~8 *** this brief communication,essential concepts and engineering elements related to high-level nuclear waste disposal are *** design models are described and discussed considering the long-time scale activity of spent nuclear fuel or high level *** of physical and chemical barriers to contain nuclear waste are *** regarding integrity,self-irradiation induced decomposition and thermal effects of decay heat on the spent nuclear fuel are also *** question of retrievability of spent nuclear fuel after disposal is considered.

摘要：Computer experiments are constructed to simulate the behavior of complex physical systems. Uniform designs have good performance in computer experiments from several aspects. In practical use, the experimenter needs to choose a small size uniform design at the beginning of an experiment due to a limit of time, budget, resources, and so on, and later conduct a follow up experiment to obtain precious information about the system, that is, a sequential experiment. The Lee distance has been widely used in coding theory and its corresponding discrepancy is an important measure for constructing uniform designs. This paper proves that all the follow up designs of a uniform design are uniform and at least two of them can be used as optimal follow up experimental designs. Thus, it is not necessary that the union of any two uniform designs yields a uniform sequential design. Therefore, this article presents a theoretical justification for choosing the best follow up design of a uniform design to construct a uniform sequential design that involves a mixture of ω≥ 1 factors with β_k ≥ 2, 1 ≤ k ≤ωlevels. For illustration of the usage of the proposed results, a closer look is given at using these results for the most extensively used six particular cases, three symmetric and three asymmetric designs, which are often met in practice.

摘要：The stability and reactivity of nanomaterials are of crucial importance for their application, but the long-term effects of stability and reactivity of nanomaterials under practical conditions are still not well understood. In this study, we first established a comprehensive strategy to investigate the stability of a highly reactive nanomaterial from the viewpoint of reaction kinetics with ultrathin tellurium nanowires （TeNWs） as a model material in aqueous solution through an accelerated oxidation process. This allowed us to propose a new approach for the design and synthesis of other unique one-dimensional nanostructures by a chemical transformation process using the intermediate nanostructures ＂captured＂ during the dynamic oxidation process under different conditions. In essence, the oxidation of ultrathin TeNWs is a gas-solid reaction which involves liquid, gas and solid phases. It has been demonstrated that the oxidation process of ultrathin TeNWs in aqueous solution can be divided into three stages, namely oxygen limiting, ultrathin TeNWs limiting and mass transfer resistance limiting stages. The apparent oxidation kinetics for ultrathin TeNWs is approximately in accord with a first order reaction kinetics model and has an apparent activation energy as low as TeNWs are thermodynamically unstable 13.53 ***^-1, indicating that ultrathin However, the unstable nature of ultrathin TeNWs is actually an advantage since it can act as an excellent platform to help us synthesize and design one-dimensional functional nanomaterials--with special structures and distinctive properties--which are difficult to obtain by a direct synthesis method.

摘要：The design and the deposition of a rugate filter for broadband applications are *** bandwidth is extended by increasing the rugate period continuously with *** width and the smoothness of the reflection band with the distribution of the periods are *** improvement of the steepness of the stopband edges and the suppression of the side lobes in the transmission zone are realized by adding two apodized rugate structures with fixed periods at the external broadband rugate filter *** rapidly alternating deposition technology is used to fabricate a rugate filter *** measured transmission spectrum with a reflection bandwidth of approximately 505 nm is close to that of the designed broadband rugate filter except a transmittance peak in the *** on the analysis of the cross-sectional scanning electron microscopic image of the sample,it is found that the transmission peak is most likely to be caused by the instability of the deposition rate.

摘要：Bionic devices are an integral part of human life,and continuous innovations in their design and functions with the help of nanotechnology has revolutionized the area of neuroscience and ***-interfaces play a key role in bionic devices such as neural implants for efficient transfer of the signal to smart *** report here on the design of a new microelectrode,comprising Carbon Nanofiber (CNF) and a biopolymer,namely carboxymethyl xyloglucan (CMX) hydrogel inside the CNF,which enhances the current density across the interface,Microelectrode was prepared by in-situ cross-linking of CMX inside CNF,with optimized CMX:CNF ratio,resulting in continuous ionic channels confined within the hollow core of *** microscopy images of microelectrodes illustrate the formation ofCMX hydrogel network inside the CNF hollow core without wrapping its *** presence of hydrogel in the CNF was confirmed by Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM).The electrochemical studies indicate the enhancement in charge density as well as the active surface area of the microelectrodes due to the presence ofCMX hydrogel *** microelectrodes have great potential as neural interfaces for designing smart prosthetics with voluntary control.

摘要：Cyanobacteria can produce useful renewable fuels and high-value chemicals using sunlight and atmo- spheric carbon dioxide by photosynthesis. Genetic manip- ulation has increased the variety of chemicals that cyanobacteria can produce. However, their uniquely abundant NADPH-pool, in other words insufficient supply of NADH, tends to limit their production yields in case of utilizing NADH-dependent enzyme, which is quite common in heterotrophic microbes. To overcome this cofactor imbalance and enhance cyanobacterial fuel and chemical production, various approaches for cofactor engineering have been employed. In this review, we focus on three approaches： （1） utilization of NADPH- dependent enzymes, （2） increasing NADH production, and （3） changing cofactor specificity of NADH-dependent enzymes from NADH to NADPH.

摘要：The finite element analysis （FEA） software Ansys was employed to study the stress state of the dies of both plane and non-plane parting face structures with uniform interference and the die of plane parting face structure with non-uniform interference. Considering the symmetry of the die, a half gear tooth model of the two-ring assembled die with 2.5 GPa inner pressure was constructed. Four paths were defined to investigate the stress state at the bottom comer of the die where stress concentration was serious. FEA results show that the change of parting face from non-plane to plane can greatly reduce the stress at the teeth tips of the die so that the tip fracture is avoided. The interference structure of the die is the most important influencing factor for the stress concentration at the bottom comer. When non-uniform interference is adopted the first principal stress at the comer on the defined paths of the die is much lower than that with uniform interference. The bottom hole radius is another important influencing factor for the comer stress concentration. The first principal stress at the comer of the plane parting face die with non-uniform interference is reduced from 2.3 to 1.9 GPa when the hole radius increases from 12.5 to 16.0 mm. The optimization of the die structure increases the life of the die from 100 to 6 000 hits.

摘要：Flow characteristics inside a cyclone filter were investigated by the use of computational fluid dynamics(CFD). For computations, SST model was adopted. Parametric study was carried out considering the filtering performance. Revolution speeds were changed from 100 to 550 with 50 increments. A skirt is the driving source for cyclone operation. The influence of several design factors, such as the skirt length, the skirt gap and the return length to filtering performance was investigated under the particle diameter 100μm of debris material(Al, s.g.=2.7). The filtering performance was also investigated with the skirt length 28 mm changing the debris diameters from 1μm to 50μm. The flow rate of the working fluid was maintained at 0.55kg/s. It has been verified that the most influential factors to the filtering efficiencies was the skirt gap between the cyclone generator and the cyclone vessel.

摘要：Osteoarthritis （OA）, identified as one of the priorities for the Bone and Joint Decade, is one of the most prevalent joint diseases, which causes pain and disability of joints in the adult population. Secondary OA usually stems from repetitive overloading to the osteochondral （OC） unit, which could result in cartilage damage and changes in the subchondral bone, leading to mechanical instability of the joint and loss of joint function. Tissue engineering approaches have emerged for the repair of cartilage defects and damages to the subchondral bone in the early stages of OA and have shown potential in restoring the joint＇s function. In this approach, the use of three-dimensional scaffolds （with or without cells） provides support for tissue growth. Commercially available OC scaffolds have been studied in OA patients for repair and regeneration of OC defects. However, none of these scaffolds has shown satisfactory clinical results. This article reviews the OC tissue structure and the design, manufacturing and performance of current OC scaffolds in treatment of OA. The findings demonstrate the importance of biological and biomechanical fixations of OC scaffolds to the host tissue in achieving an improved cartilage fill and a hyaline-like tissue formation. Achieving a strong and stable subchondral bone support that helps the regeneration of overlying cartilage seems to be still a grand challenge for the early treatment of OA.