Theoretical Study of Aln and AlnO (n = 2—10) Clusters

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Effects of trapped electrons on off-axis lower hybrid current drive in tokamaks

The effects of trapped electrons on off-axis lower hybrid current drive （LHCD） in tokamaks are studied, A computer code for solving the Fokker-Planck equation in a toroidal geometry is developed and employed. The code is suitable for various auxiliary heating and current drive schemes in tokamak plasmas. The influence of the resonance regime on the current drive efficiency as well as the influence of trapped particle fraction on the current drive efficiency are emphasized. It is shown that, as an electrostatic force, the lower hybrid wave causes some of the trapped electrons to be untrapped and lose their energy, which can cut the LHCD efficiency by about 30%. The ITER scaling law is also used to estimate the trapped electron effects.[第一段]     

复合材料铺层拼接层间断裂韧性的试验研究

针对评价复合材料层合板层间断裂韧性的测量,提出了用拉伸试验法测定Ⅱ型层间断裂韧性,设计了内含铺层拼接区的分层破坏试验层合板,制备了拉伸试件.通过拉伸试验测得了拼接区开裂和分层裂纹稳态扩展过程中的载荷与变形规律:层间破坏具有Ⅱ型断裂特征,且裂纹扩展比较稳定.利用测试数据计算出断裂功,并以临界能量释放率表示层合板的Ⅱ型层间断裂韧性,结果表明用铺层拼接件拉伸法进行层间断裂韧性试验是可行的.     

4-甲基儿茶酚：一种神经生长因子诱导物对老龄鼠学习记忆功能的影响

目的：观察外周应用４－ＭＣ对老龄鼠学习、记忆功能的影响,以期对４－ＭＣ能否促进中枢神经系统内源性ＮＧＦ的产生,并进而通过ＮＧＦ改善老龄鼠的脑功能做进上步的研究。方法：１０ｇ／ｋｇ体重小鼠腹腔内注射给药,对照组１０ｍｍｏｌ／Ｌ的维生素Ｃ溶液等量,用药１周后行Ｍｏｒｒｉｓ水迷宫训练,连续７ｄ,第１５天进行一次水迷宫测试,记录其逃生时间,考查空间定位的学习和记忆能力。结果：实验结果主宰了外周应用４－ＭＣ     

Fragmentation of Magic-Size Cluster Precursor Compounds into Ultrasmall CdS Quantum Dots with Enhanced Particle Yield at Low Temperatures

Colloidal small-size CdS quantum dots (QDs) are produced usually with low particle yield, together with side products such as the particular precursor compounds (PCs) of magic-size clusters (MSC). Here, we report our synthesis of small-size CdS QDs without the coexistence of the PC and thus with enhanced particle yield. For a conventional reaction of cadmium oleate (Cd(OA)₂) and sulfur (S) in 1-octadecene (ODE), we show that after the formation of the PC in the pre-nucleation stage, the addition of tri-n-octylphosphine oxide (TOPO) facilitates the production of small-size QDs. We demonstrate that TOPO fragmentizes the PC that have formed, which enables the nucleation and growth of small-size QDs even at room temperature. Our findings introduce a new approach to making small-size QDs without the coexistence of the PC and with improved particle yield. Providing experimental evidence for the two-pathway model proposed for the pre-nucleation stage of colloidal binary QDs, the present study aids in the advance of non-classical nucleation theory.     

Precipitate orientation relationships and interfacial structures in duplex stainless steel Zeron-100

Precipitation in a commercial duplex stainless steel, Zeron-100, has been investigated using conventional and high-resolution electron microscopy. Acicular fcc precipitates of Ni-rich nphase formed in the Cr-rich fmatrix by suitable heat treatment. The orientation relationships between a large number of particles and the matrix were studied and found to be distributed in a range between the Kurdjumov-Sachs and the Pitsch relationships. All particles were observed to be bounded by two types of longitudinal facets, designated I and C, representing 'incoherent' and 'coherent'. High-resolution microscopy showed that the I facet was based on the (112) alpha /(101) nincommensurate interface between Pitsch-related crystals. The C facet exhibited a coherent terrace structure with coherency strain parallel to accommodated by a disconnection array, causing the adjacent crystals to be slightly misoriented from the Kurdjumov-Sachs relationship. The orientational incompatibility between the I and C reference structures, 5.76° about , was found to be accommodated by networks of n-crystal dislocations superimposed on the facets. These acted as tilt walls of dislocations, but, although their combined angular tilt was always observed to equal about 5.7°, this was not partitioned between the I and C facets in a unique manner. Such differential partitioning of the incompatibility offers a natural explanation for the observed variation in particle orientation. Some issues, such as the growth mechanism, were not resolved and need further work.     

多段翼型吹气流动分离控制研究

基于雷诺平均Navier-Stokes粘性流动方程,采用数值模拟方法,分析了吹气控制对多段翼型气动性能的影响,阐述了吹气改善多段翼型流动的机理。采用有限体积法对雷诺平均Navier-Stokes方程进行空间离散,时间方向推进采用二阶迎风格式,湍流模型采用SST k-ω模型。结果表明:在多段翼型基础上采取吹气控制可以获得很好的气动增升效果,三段翼型的最大升力系数可达4.98;吹气可改善多段翼型表面流动,减小其流动分离,增加升力;在同样的吹气口几何参数条件下,在一定范围内增大吹气动量系数可以提高多段翼型的升力系数;在多段翼型主翼后段和襟翼同时施加吹气流动控制可以获得更好的效果,升力系数比基本三段翼型(基本构型A)增加30.05%。     

Minimum spanning trees for community detection

A simple deterministic algorithm for community detection is provided by using two rounds of minimum spanning trees. By comparing the first round minimum spanning tree (1st-MST) with the second round spanning tree (2nd-MST) of the network, communities are detected and their overlapping nodes are also identified. To generate the two MSTs, a distance matrix is defined and computed from the adjacent matrix of the network. Compared with the resistance matrix or the communicability matrix used in community detection in the literature, the proposed distance matrix is very simple in computation. The proposed algorithm is tested on real world social networks, graphs which are failed by the modularity maximization, and the LFR benchmark graphs for community detection.     

Et3N-catalyzed oxidative dehydrogenative coupling of α-unsubstituted aldehydes and ketones with aryl diamines leading to quinoxalines using molecular oxygen as oxidant

A novel Et₃N-catalyzed oxidative dehydrogenative coupling of α-unsubstituted carbonyl compounds with aryl diamines leading to quinoxaline derivatives using molecular oxygen as oxidant has been developed. Six hydrogen dissociations involving 2 sp³ C–H bonds activation are realized under mild conditions in this approach. Plausible mechanism is proposed for this novel Et₃N-catalyzed transformation on the basis of the aboratively designed mechanistic studies including the radical detection by EPR. ^©2012 Elsevier Science. All rights reserved.