Effect of pile spacing on pile demand for small pile groups in laterally spreading soil

Liquefaction-induced lateral spreading has been responsible for widespread damage to pile foundations in many large earthquakes. The specification of inertial and kinematic pile and pile cap demands is a particularly challenging aspect of the analysis of pile foundations in laterally spreading soils. This paper presents and examines the results from a pair of dynamic centrifuge tests focusing on pile and pile cap demands for small pile groups with different pile spacings. Inertial and kinematic pile cap forces and lateral pile group interaction are examined with regard to the overturning mechanism that dominated the pile group response. © 2014 Taylor & Francis Group.

Metalorganic chemical vapor deposition of GaNAs alloys using different Ga precursors

The GaNAs alloys have been grown by metalorganic chemical vapor deposition (MOCVD) using dimethylhydrazine (DMHv) as the nitrogen precursor, triethylgallium (TEGa) and trimethylgallium (TMGa) as the gallium precursors, respectively. Both symmetric (004) and asymmetric (1 1 5) high-resolution X-ray diffraction (HRXRD) were used to determine the nitrogen content in GaNAs layers. Secondary ion mass spectrometry (SIMS) was used to obtain the impurity content. T e influence of different Ga precursors on GaNAs quality has been investigated. Phase separation is observed in the < 1 1 5 > direction when using TMGa as the Ga precursor but not observed when using TEGa. This phenomenon should originate from the parasitic reaction between the Ga and N precursors. Furthermore. samples grown with TEGa have better quality and less impurity contamination than those with TMGa. Nitrogen content of 5.742% has been achieved using TEGa and no phase separation observed in the sample. (C) 2002 Elsevier Science B.V. All rights reserved.

TDR和FDR测定黄绵土土壤含水量的标定

时域反射仪(TDR)与频率反射仪(FDR)是目前最为先进,并且最具有发展前途的土壤含水量测量仪器。有便利、快捷、准确的优点。介绍了6种基于TDR或FDR原理的仪器对黄绵土含水量进行试验标定的方法与结果。标定结果表明:仪器的测量值与烘干法的测量值之间有一定的差异,CS616和Trime-T3烘干法测定结果接近,但是其余的4种仪器测定值均高于烘干法测定值,在应用这些仪器测定土壤含水量时需要进行标定。

聚丁二烯红外和拉曼光谱微结构分析

本工作对聚丁二烯(PBD)进行了光谱微结构分析，主要考察了三个问题。1、PBD分子链构象对PBD红外光谱的影响本工作对高顺式(c)PBD样品进行了室温和低温(25℃和-150℃)红外光谱测定，发现高顺式PBD在低温下整个光谱吸收峰大部分峰宽变窄，峰强增加，特别是738cm~(-1)峰，在低温下位移至748cm~(-1)，峰强增加一倍多。另外还观察到低温结晶态出现802和598cm~(-1)两个吸收峰，在以前文献中未曾有过报导，我们将它们归属为顺式结构结晶峰。通过计算分峰，原来738cm~(-1)峰分成两个位于742和727cm~(-1)的子峰，在低温下，两个子峰分别位移至748和735cm~(-1)，与室温时比较，两个子峰半宽都明显变小。748cm~(-1)子峰峰强也大大增加。结构分析表明，顺式结构特征振动CH=CH面外变角与分子链的构象有密切联系，而仅式(T)和1.2(v)结构却不存在这种情况，因而967cm~(-1)(T)和911cm~(-1)(v)两特征峰低温下变化都很小。本工作认为顺式结构738cm~(-1)峰这一变化是由于顺式结构不同分子链构象所造成的。低温和室温下分峰所得的左子峰对应于最稳定构象产生的吸收，右子峰则对应于相对不稳定构象产生的吸收。同时本工作肯定了米晋瑁等人提出的红外光谱定量分析方法在高顺式样品中的适用性。2、PBD分子链序列结构对红外光谱的影响由于在非高顺式样品中存在CCC、CCT、CCV、TCV、TCT、VCV等多种序列形式，通过不同组成的PBD红外光谱分析，发现在乙烯基含量中、高的样品中，原来738cm~(-1)峰已不再存在，峰值出现在733cm~(-1)附近，而且受1.2结构部分吸收的严重影响，顺式结构CH=CH面外变角吸收已不再是顺式结构的特征峰。通过对850至650cm~(-1)光谱区的光谱解析，本工作认为朱晋瑁等人的红外光谱定量分析方法在乙烯含量中、高的样品中已不再适用。3、PBD拉曼光谱的微结构分析本工作对PBD拉曼光谱1600-1700cm~(-1)区进行了光谱测定，选择了1666、1652和1639.5cm~(-1)吸收峰作为T、C和V构型的特征峰，借助于景遐斌老师的计算分峰方法，对PBD样品进行微结构分析，结果表明，各吸收带拟合良好，特征峰峰位稳定，分别在1666±1、1652±1.5和1639.5±1 cm~(-1)，半峰宽变化不大，峰与峰之间相互影响很小，也就是说，我们选用的特征峰是合理的。用分峰所得的相对面积，结合~1H-NMR测得的值，建立了拉曼光谱PBD定量分析方法。用这一方法对27个不同微结构组成的PBD样品进行分析，所得结果与~1HNMR（高顺式样品与~(13)C-NMR、IR）比较，绝大部分样品一致性很好，最大偏差小于2%。本工作认为，用1666、1652和1639.5cm~(-1)碳双键伸缩振动吸收峰作为T、C和V构型特征峰进行定量分析，在理论上是合理的，在实际上是可行的。而且本方法直接使用固体样品，不经任何溶解和处理，所有计算处理在微机上即可实现，操作和计算都很方便。

Shubnikov de Haas oscillations of a two-dimensional electron gas in a modulation-doped Zn0.80Cd0.20Se/ZnS0.06Se0.94 single quantum well

The magnetotransport properties of the two-dimensional (2D) electron gas confined in a modulation-doped Zn0.80Cd0.20Se/ZnS0.06Se0.94 single quantum well structure were studied at temperatures down to 0.35 K in magnetic fields up to 7.5 T. Well resolved 2D Shubnikovde Haas (SdH) oscillations were observed, although the conductivity of the sample in the as grown state was dominated by a bulk parallel conduction layer. After removing most of the parallel conduction layer by wet chemical etching the amplitude and number of SdH oscillations increased. From the temperature dependence of the amplitude the effective mass of the electrons was estimated as 0.17 m(0). Copyright (C) 1996 Published by Elsevier Science Ltd

GaN横向外延中晶面倾斜的形成机制

采用双晶X射线衍射（DC－XRD）研究蓝宝石（0001）衬底上横向外延GaN层中晶面倾斜的形成原因。发现横向生长区的GaN在垂直掩模方向上朝SiNx掩模层弯曲。采用选择性腐蚀逐渐去掉SiNx掩模层，发现XRD中G N(002)ω扫描衍射峰两侧存在与晶面倾斜有关的衍射信息。该衍射信息起初为一个很宽的峰，随着选择性腐蚀的进行，会先分裂为两个峰，最后当SiNx掩模层全部腐蚀掉后，其中一个衍射峰会消失，而只剩下一个很窄的峰。作者证实造成横向外延GaN中晶面倾斜的原因有两个

RBE of cells irradiated by carbon ions

于1905-07-02批量导入IMP-IR

A new dual injection system for AMS facility

IEECAS SKLLQG

碳离子辐照细胞的相对生物学效率

研究了传能线密度 (LET)≥ 1 2 5.5keV μm的碳离子辐照小鼠黑色素瘤B1 6、人的宫颈癌HeLa、中国仓鼠肺V79、人的肝癌SMMC 772 1 4种细胞的相对生物学效率 (RBE) .得到了当LET =1 2 5.5keV μm时 ,RBE依赖于细胞种类并随细胞存活水平的升高而增加的关系 ,以及当LET≥ 1 2 5.5keV μm时 ,RBE随着LET的增大而变小的关系