Accelerator Analysis of Tributyltin Adsorbed onto the Surface of a Tributyltin Resistant Marine Pseudoalteromonas sp. Cell

Tributyltin (TBT) released into seawater from ship hulls is a stable marine pollutant and obviously remains in marine environments. We isolated a TBT resistant marine Pseudoalteromonas sp. TBT1 from sediment of a ship’s ballast water. The isolate (10^{9.3 ± 0.2} colony-forming units mL⁻¹) adsorbed TBT in proportion to the concentrations of TBTCl externally added up to 3 mM, where the number of TBT adsorbed by a single cell was estimated to be 10^8.2. The value was reduced to about one-fifth when the lysozyme-treated cells were used. The surface of ethanol treated cells became rough, but the capacity of TBT adsorption was the same as that for native cells. These results indicate that the function of the cell surface, rather than that structure, plays an important role to the adsorption of TBT. The adsorption state of TBT seems to be multi-layer when the number of more than 10^6.8 TBT molecules is adsorbed by a single cell.     

Quantification of the layer dispersion degree in polymer layered silicate nanocomposites by transmission electron microscopy

As the performance of polymer layered silicate nanocomposites strongly depends on their interior layer dispersion, quantification of the layer dispersion degree is needed. In this work, a new methodology was developed to determine the dispersion parameter D_0.1, based on the measurement of the free-path spacing distance between the single clay sheets from the transmission electron microscopy (TEM) images. Several examples of exfoliated, intercalated, and immiscible composites were studied. It was found that the exfoliated composites had D_0.1 over 8%, while that of intercalated composites were between 4 and 8%. In the case of intercalation, a high frequency peak appeared at a short spacing distance in the histogram, which was a characteristic of the intercalation, distinct from the exfoliation. The main utility of this TEM methodology is for the quantification of exfoliated or intercalated samples with small number of layers with stacks. The dispersion parameter D_0.1 below 4% was suggested to classify as immiscible. A unique advantage of the TEM measurement is that the dispersion degree of different fillers can be counted individually.     

Focal adhesion interactions with topographical structures: a novel method for immuno-SEM labelling of focal adhesions in S-phase cells

Current understanding of the mechanisms involved in osseointegration following implantation of a biomaterial has led to adhesion quantification being implemented as an assay of cytocompatibility. Such measurement can be hindered by intra-sample variation owing to morphological changes associated with the cell cycle. Here we report on a new scanning electron microscopical method for the simultaneous immunogold labelling of cellular focal adhesions and S-phase nuclei identified by BrdU incorporation. Prior to labelling, cellular membranes are removed by tritonization and antigens of non-interest blocked by serum incubation. Adhesion plaque–associated vinculin and S-phase nuclei were both separately labelled with a 1.4 nm gold colloid and visualized by subsequent colloid enhancement via silver deposition. This study is specifically concerned with the effects microgroove topographies have on adhesion formation in S-phase osteoblasts. By combining backscattered electron (BSE) imaging with secondary electron (SE) imaging it was possible to visualize S-phase nuclei and the immunogold-labelled adhesion sites in one energy 'plane' and the underlying nanotopography in another. Osteoblast adhesion to these nanotopographies was ascertained by quantification of adhesion complex formation.     

Influence of zero-loss filtering on electron optical phase contrast

Complex scattering amplitudes are used to calculate the phase contrast of colloidal gold particles. Comparison of measurements of the phase contrast intensity at the centre of the gold particle as a function of defocus for unfiltered and zero-loss filtered images demonstrates the increase in phase contrast achieved by zero-loss filtering even for a thick carbon substrate film. The granulation of amorphous germanium films is measured by the spatial rms (root mean square) values of image intensity in a defocus series.     

LB技术制备大面积超薄PMMA抗蚀层的研究

采用自行研制的ＬＢ自动提膜装置，制备出大面积（１０×８ｃｍ２）、高质量的ＰＭＭＡ超薄抗蚀剂膜，并将其用于高分辨率铬掩模版的研制。通过电子束曝光，湿法蚀刻，制作了分辨率优于０．５μｍ，特征线宽０．３８μｍ的４（１００ｍｍ）铬掩模版。     

The electron microscopy of post-growth induced defects of ZnSe/GaAs epilayers

A fundamental research of structural defects induced upon post-growth processing of ZnSe/GaAs epilayers grown on (100) GaAs was done by identifying defect-related reflections in the transmission electron diffraction (TED) patterns of ZnSe. Structural artifacts, other than the as-grown defects, on this material system could be excluded according to our results. Four types of abnormal reflections have been observed in addition to primary reflections. These extra reflections are sensitive to the post-growth processing of ZnSe epilayers and may arise from various external effects, rather than epitaxy growth, such as irradiation damage, surface oxidation, and surface contamination. By mapping these reflections at several major zone axes using TED patterns, we found that the reciprocal lattice for a ZnSe crystal with structural defects consists of two distinct types of extra reflections associated with irradiation damage. The first type of extra reflections is ±1/3{111} and the other is ±1/2{111} corresponding to pure-edge and non-edge dislocation loops, respectively. For (100) oriented wafers, the ±1/3{111} and ±1/2{111} reflections were observed only on two of the four possible 〈111〉 variants (i.e. [111]_Zn and [111]_Zn)and this phenomenon was attributed to the anisotropy of defect distribution. Extra reflections associated with surface oxidation and contamination are also observed. The orientation relationships between a surface hexagonal ZnO and a cubic ZnSe film are [0001]_ZnO//[−111]_ZnSe, and [01−11]_ZnO//[011]_ZnSe. The origin, characterization, and elimination of these induced reflections are discussed. With the knowledge about these extra effects on structural defect formation, we have shown the real microstructure of ZnSe epilayers.     

影响碲镉汞晶体电子迁移率的主要因素

通过把迁移率的实测值与影响ＨｇＣｄＴｅ晶体电子迁移率的主要散射机构进行对比，得出结论：位错是ＨｇＣｄＴｅ晶体低温电子迁移率降低的主要原因。     

The summary of researches on ADS in China

The conceptual study on the accelerator driven system (ADS) that lasted for about five years ended in 1999 in China. As one project of the National Basic Research Program of China (973 Program) in the energy domain, which is sponsored by the China Ministry of Science and Technology (MOST), a five-year-program of fundamental research of ADS physics and related technology was launched in 2000 and passed national review at the end of 2005. The China Institute of Atomic Energy (CIAE), the Institute of High Energy Physics (IHEP), the Institute of Heavy Ion Physics in Peking University (PKU-IHIP) and other institutions jointly carried out the research. The research activities were focused on HPPA physics and technology, reactor physics of external source driven sub-critical assembly, nuclear data base and material study. For HPPA, a high current injector consisting of an ECR ion source, LEBT and an RFQ accelerating structure of 3.5 MeV was built. In reactor physics study, a series of neutron multiplication experimental study has been carried out and still being done. The VENUS facility has been constructed as the basic experimental platform for neutronics study in ADS blanket. It’s a zero power sub-critical neutron multiplying assembly driven by external neutron produced by a pulsed neutron generator. The theoretical, experimental and simulation study on nuclear data, material properties and nuclear fuel circulation related to ADS is carrying on to provide the database for ADS system analysis. The main results on ADS related researches will be reported.     

Energy relaxation in GaInAs/AlInAs heterojunctions and GaAs/AlGaAs multiple quantum wells

We have studied electron energy relaxation in GaInAs/AlInAs heterojunctions and GaAs/AlGaAs multiple quantum wells using mobility measurements as a function of electric field and temperature, in the range 3K to 300K. The results in the range 3 to 20K show a power loss rate which is dependent on (T_e − T_l), suggesting that the energy relaxation occurs through acoustic phonon scattering. At electron temperatures greater than 20K, the experimental results are modelled using a standard expression for polar optical phonons. This modelling yields 30meV and 31meV for the polar optical phonon energy in GaAs and InGaAs respectively.     

热场致发射电子源曝光系统的技术现状和应用前景

高亮度、长寿命的热场致发射(Thermal field emitter)阴极自七十年代中期已受到人们的关注和重视,历经十多年在理论分析、工艺制备和实验研究上做了大量工作之后,于1988年在电子束曝光机上的应用中取得了突破性进展。用晶向为(100)的钨和具有低逸出功的锆制成的(Zr/O/W)热场致发射阴极在四千小时的使用寿命下亮度值超过六硼化镧阴极一个数量级以上,最近的实验结果表明:在工件台上小束斑下能得到接近两千安培每平方厘米的束流密度,而且四十小时内束流稳定度接近千分之一。显然,这几个表征曝光系统综合技术性能的重要指标,说明多年困扰于各种电子束曝光系统(特别是高斯圆斑电子束系统)在高分辨率情况下生产率较低的技术难题已经得到了比较圆满的解决。 八十年代末期,当热场致发射电子源曝光系统的技术关键解决后,这项技术就成为技术发达国家,特别是美国和日本,在电子束曝光领域进行技术竞争的热点;九一年五月底在美国召开的国际三束会议上有关场致发射阴极和MEBES—4型机已经采用TFE的最新报道充分证实了这项技术在电子束曝光技术应用中的重要地位和发展潜力。