Structural phase transition of vanadium at 69 GPa

A phase transition was observed at 63-69 GPa and room temperature in vanadium with synchrotron x-ray diffraction. The transition is characterized as a rhombohedral lattice distortion of the body-centered-cubic vanadium without a discontinuity in the pressure-volume data, thus representing a novel type of transition that has never been observed in elements. Instead of driven by the conventional s-d electronic transition mechanism, the phase transition could be associated with the softening of C44 trigonal elasticity tensor that originates from the combination of Fermi surface nesting, band Jahn-Teller distortion, and electronic topological transition.     

Spectroscopic evidence of the multiple- site structure of Eu(3+) ions incorporated in ZnO nanocrystals

Hexagonal Eu(3+):ZnO nanocrystals were synthesized by a modified solgel method. By means of the site-selective spectroscopy at 10 K, two kinds of luminescence sites of Eu(3+) are identified. One site exhibits a long lifetime of (5)D(0) and sharp emission and excitation peaks, which are ascribed to the inner lattice site with an ordered crystalline environment. The other site associated with the distorted lattice sites near the surface shows a relatively short lifetime of (5)D(0) and significantly broadened fluorescence lines. The energy transfer from the nanocrystal host to Eu(3+) confirms that Eu(3+) ions can, to some extent, be incorporated into the ZnO nanocrystal.     

Quantitative analysis of asymmetrical cortical activity in motor areas during sequential finger movement

Brain asymmetry is a phenomenon well known for handedness and has been studied in motor cortices. However, few quantitative studies on asymmetrical cortical activity in motor areas have been conducted. In this study, we systematically investigated asymmetrical cortical activity in motor areas during sequential finger movement by quantitatively analyzing functional magnetic resonance imaging (fMRI) blood oxygenation level-dependent (BOLD) responses. The norm of BOLD signal percentage of change was introduced to quantitatively measure the BOLD signal intensity change difference between the left and right motor areas. The results of the data collected from six subjects show that the norm of BOLD signal percentage of change in the right motor area is higher than that in the left motor area for two-hand movement (P=.0059) and single-hand movement (P=.0279) with right-handedness. These results from fMRI show the asymmetry of motor areas and may suggest that the left hemisphere motor area comes into being as an adaptation system that needs few neuron cells only to finish any movement task for right-handedness. The activation intensity in the left motor area is reduced with normal right finger movement. The activation intensity in the right motor area is obviously higher than that in the left motor area.     

Antennal morphology, structure and sensilla distribution in Microplitis pallidipes (Hymenoptera: Braconidae)

Microplitis pallidipes (Hymenoptera: Braconidae) is an important larval parasitoid of noctuid larval pests. In this study, we describe the morphology, ultrastructure and distribution of sensilla on the antennae of both male and female adults using scanning electron microscopy; complemented with transmission electron microscopy. Observations determined that the antennae of M. pallidipes were threadlike and the flagella were composed of 16 sub-segments. Totally, there were six types of sensilla found on the antennae. They were identified as Sensilla trichodea, Sensilla chaetica, Sensilla basiconica type I, S. basiconica type II, Sensilla coeloconicum, and elongated Sensilla placodea, respectively. The S. trichodea were the most abundant sensilla and distributed over the entire antennae, while S. basiconica I and II, S. coeloconicum, and elongated S. placodea were limited to the flagellum. S. chaetica were found on the scape and pedicle in very low numbers. The S. basiconica II and elongated S. placodea walls were full of pores as evident in transmission electron micrographs. Though the shape and structure of antennae between male and female adults were not basically different, the length and width of the antennae on male wasps were significantly greater than that of females. Also, the number, size and density of S. placodea of the male were significantly greater than those of females. The morphology and structure of these sensilla were compared with that found in other braconid wasps. Their possible functions are discussed in light of previously published literature.     

Rapid determination of radon progeny concentration based on artificial neural networks

Journal of Radioanalytical and Nuclear Chemistry - The rapid measurement of radon progeny concentration is of great significance for improving the efficiency of radon exposure dose evaluation in a...     

Near Infrared Spectroscopy of the Cretaceous Red Beds in Inner Mongolia DongshengmiaoSCIEI北大核心CSCD

Take the cores and surface weathered soil from the Cretaceous red beds in the western of Dongshengmiao mine of Inner Mongolia and analysis with near-infrared spectroscopy. The result shows that near-infrared spectroscopy can identify mineral quickly through the characteristic absorption peaks of each group. The Cretaceous red beds in the western of Dongshengmiao mine is argillaceous cementation, it is mainly composed of quartz, feldspar, montmorillonite, illite, chlorite, muscovite etc, the mineral composition is mainly affected by the upstream source area. The clay mineral like montmorillonite water swelling and uneven drying shrinkage expands the original crack and creates new cracks, reduces its strength, which is the mainly reason of its disintegration. According to the composition of clay mineral, we speculate its weathering process is mainly physical weathering, the climate during the weathering is cold and dry. The results can not only improve the geological feature of the mining area, but also show that the near-infrared spectroscopy technology can analyze the mineral composition of soil and rock effectively on the basis of Mineral spectroscopy, which demonstrates the feasibility of the near-infrared spectroscopy can analyze minerals in soil and rock quickly, that shows the feasibility in geology study, provides new ideas for the future research of soil and rock.     

微小型组合导航系统软硬件协同设计

针对机载制导武器对组合导航系统小体积、低功耗、高实时性以及高可靠性的要求,设计了组合导航系统双CPU总体方案。基于Zynq全可定制平台搭建了组合导航系统硬件环境。在分析组合导航系统软件结构的基础上,对任务块、任务优先级以及任务间的同步机制进行了合理设计;同时基于对组合导航滤波器内数据交换的分析,通过设置消息队列实现了任务间通信,且在保证数据一致性的同时,避免了“死锁”问题的出现。     

表面活性剂辅助二氧化硅纳米颗粒在非水基液中的分散研究（英文）

研究了粒径10~100nm的二氧化硅纳米颗粒在非水基液中的表面活性剂辅助分散。结合颗粒表面特定官能团结构,针对性选择了合适的表面活性剂,氢键桥梁作用和长链分子空间位阻作用抑制了颗粒团聚行为。当表面活性剂体积分数6%的时候,动态光散射测试结果表明颗粒中位尺度30.2nm,与透射电镜测试结果吻合,展现了良好的分散性。