一种改进的最大簇中心定位算法

针对煤矿井下人员定位困难以及现有定位算法存在较大定位误差的问题,基于非测距定位技术提出一种改进的最大簇中心定位算法。该算法利用接收信号强度指示器的输出值对移动节点在定位区域中的位置进行归类,改进簇的生成条件和归类逻辑以解决现有定位算法存在的定位盲点问题。数值仿真与实验结果表明,该算法具有较高定位精度,适合于井下复杂多变的通信环境。

幼稚前体细胞异常定位结构特点与急性髓系白血病早期复发的相关性分析

目的：比较骨髓大簇和小簇幼稚前体细胞异常定位（ALIP）结构与急性髓系白血病（AML）复发的相关性。方法：以抽吸-活检-步取材法采集化疗后AML患者骨髓，将涂片原始细胞数〈5％、切片无ALIP结构者视为真正骨髓完全缓解（CR）；涂片原始细胞数〉5％为典型复发。跟踪观察31例缓解后AML患者骨髓切片，直至涂片复发。当骨髓切片小梁旁区或间区检出3～5个幼稚前体细胞聚集在一起视为小簇ALIP，5个以上聚集在一起视为大簇ALIP。分析大簇、小簇ALIP结构的出现与复发的相关性，并比较其差异。结果：31例骨髓涂片及切片CR的患者中，有22例在随访病程中骨髓切片出现ALIP结构，占71％，ALIP结构的出现与复发有明显的相关性（P〈0．05），且大簇ALIP结构与复发的相关性明显高于小簇ALIP结构（P〈0．05）。切片出现大簇ALIP结构的患者（77±35）d后涂片出现典型复发，小簇ALIP结构者经（150±43）d出现典型复发。结论：骨髓切片上出现ALIP结构者多在短期内出现骨髓涂片复发，其检测复发早于涂片，并且大簇ALIP结构较小簇AL—IP更有价值。

Solid−solid phase transition of tungsten induced by high pressure:A molecular dynamics simulation

The phase transition of tungsten(W)under high pressures was investigated with molecular dynamics simulation.The structure was characterized in terms of the pair distribution function and the largest standard cluster analysis(LSCA).It is found that under 40−100 GPa at a cooling rate of 0.1 K/ps a pure W melt first crystallizes into the body-centred cubic(BCC)crystal,and then transfers into the hexagonal close-packed(HCP)crystal through a series of BCC−HCP coexisting states.The dynamic factors may induce intermediate stages during the liquid−solid transition and the criss-cross grain boundaries cause lots of indistinguishable intermediate states,making the first-order BCC−HCP transition appear to be continuous.Furthermore,LSCA is shown to be a parameter-free method that can effectively analyze both ordered and disordered structures.Therefore,LSCA can detect more details about the evolution of the structure in such structure transition processes with rich intermediate structures.

Floating Escherichia coli by Expressing Cyanobacterial Gas Vesicle Genes

Gas vesicles are hollow, air-filled polyprotein structures that provide the buoyancy to cells. They are found in a variety of prokaryotes. In this study, we isolated a partial gas vesicle protein gene cluster containing gvpA and gvpC20ψ from Planktothrix rubescens, and inserted it into an expression vector and expressed it in E. coli. The gas vesicle was developed in bacterial cells, which made bacterial cells to float on medium surface. We also amplified gvpA and gvpC20ψ separately and synthesized an artificial operon by fusing these two genes with the standardized gene expression controlling elements of E. coli. The artificial operon was expressed in E. coli, forming gas vesicles and floating bacteria cells. Our findings verified that the whole set of genes and the overall structure of gas vesicle gene cluster are not necessary for developing gas vesicles in bacteria cells. Two genes, gvpA and gvpC20ψ, of the gas vesicle gene cluster are sufficient for synthesizing an artificial operon that can develop gas vesicles in bacteria cells. Our findings provided a wide range of applications including easing the harvest of cultured microalgae and bacteria, as well as enriching and remediating aquatic pollutants by constructing gas vesicles in their ceils.

Preparation and Characterization of Macroporous Resin Immobilized Pd－Cu Bimetallic Cluster Catalysts

The Solvated Metal Atom Impregnation (SMAI) technique was employed to prepare macroporous resin immobilized Pd--Cu bimetallic cluster catalysts. The X--ray diffraction (XRD) and transmission electron micrograph (TEM) showed that Pd--Cu alloy was formed and the particle sizes of Pd--Cu clusters were very small, with average diameters <3nm. X--ray photoelectron spectroscopy indicated that both Pd and Cu were in zero--valent state. The catalytic activities of the macroporous resin immobilized Pd--Cu catalysts in hydrogenation of 4--methyl--3--penten--2--one were much greater than that of the carbon supported Pd--Cu catalysts.

科研合作网络弹性研究与实证

阐述科研合作网络弹性的概念、研究意义与应用,并以全球100所高校在图书情报学领域所组成的科研合作网络为例,选取网络最大簇规模和网络效率作为网络弹性测度指标,讨论节点点度失效、介数失效以及随机失效策略下该科研合作网络的弹性。结果显示,科研合作网络对随机节点失效具有较强的鲁棒性,其网络容错能力较强;对选择性节点失效的网络抗攻击能力较弱;网络效率相对于网络最大簇规模更适合作为科研合作网络弹性的测度指标。

Large clusters of gold deposits and large-scale metallogenesis in the Jiaodong Peninsula, Eastern China

The Jiaodong Peninsula is the largest repository of gold in China based on the production in history. It covers less than 0.2% of China's territory, but production of gold accounts for about one fourth of the whole country. Thus, the Jiaodong Peninsula is a typical area or case of large-scale metallogenesis and a large clusters of mineral deposits in China. It is characterized by the large clusters of gold deposits in large scale, high reserve and short mineralizing stage. In this study, we suggest that the eastern boundary of the large clusters of gold deposits is as same as that of North China Block, the gold deposits are hosted by Archean metamorphic rocks or Mesozoic granites, and the age of gold mineralization is 121.6 to 122.7 Ma. Gold and related ore-forming materials are derived from multisources, i.e. Archean metamorphic rocks, granites and intermediate-mafic dikes, especially, intermediate-mafic dikes and calc-alkaline granites. The metallogenic geodynamic process is constrained by the tectonic evolution of eastern North China Block during Late Mesozoic, and it is the result of the interaction between mantle and crust as the boundary plates are playing role on the block.