高场强MR和CT在急性脑出血中的诊断价值比较

对临床72例急性期脑出血分别进行CT及MR检查,通过脑内血肿量测定及两住有经验诊断医生的分析诊断,比较两项检查的诊断敏感性,探讨高场强MR在诊断急性脑出血中的价值。测量所得MR各序列和CT血肿量差异无统计学意义。敏感性比较T2＊WI和CT组差异无统计学意义,P〈0．01。T1WI和T2WI序列的敏感性相对较差,与CT组比较差异有统计学意义,P〈0．01。MR梯度回波T2＊WI对诊断急性脑内血肿的敏感性和CT检查相当,结合常规扫描序列在急性期脑内血肿的诊断和鉴别诊断中具有实际应用价值。     

螺旋CT双期增强薄层扫描对小胰腺癌诊断的研究

为了研究螺旋CT胰腺期、肝脏期双期增强薄层扫描在小胰腺癌早期诊断中的作用,对25例小胰腺癌患者行螺旋CT双期增强扫描,结果显示,两组观察结果经统计学处理有显著性差异,螺旋CT动态增强薄层2mm扫描比5mm扫描可明显提高小胰腺癌和微胰腺癌的检出率,对小胰腺癌的早期诊断有重要的临床价值。肝脏期扫描为临床确定肿瘤是否能够手术切除提供科学依据。     

3D shape and orientation of nanoscale Pb inclusions at grain boundaries in Al observed by TEM and STEM tomography

We have combined high-angle annular dark field/scanning transmission electron microscopy (HAADF-STEM) tomography with bright field (BF)-TEM tomography to characterize small inclusions of Pb at a grain boundary in Al. It was found that the shape of the grain boundary inclusions is more complex than previously thought. By using moiré fringes observed at some orientations of the specimen in a BF-TEM tomographic tilt series, we were able to determine the orientation of each grain, the axis and angle of misorientation of the grain boundary, and the facet planes of the grain boundary inclusions. The 3D shape of the inclusions was determined by merging this information with the HAADF-STEM tomography.     

An ordered arrangement of atom columnar clusters in a pentagonal quasiperiodic lattice of an Al-Ni-Co decagonal quasicrystal

The structure of an Al-Ni-Co decagonal quasicrystal (called the S1-type superstructure), which shows diffraction patterns with superlattice reflections, has been studied by atomic-scale observations of electron microscopy. The structure of the decagonal quasicrystal can be characterized as an ordered arrangement of two kinds of atom columnar cluster with different directions of pentagonal symmetry. A fundamental lattice, which is constructed by connecting all the atom clusters, shows a pentagonal quasiperiodic lattice with a bond length of about 2 nm. The pentagonal lattice is divided into two superlattices, which are constructed by connecting atom clusters with the same directions of pentagonal symmetry, with a bond length of 2     

Tailoring of interfaces in amorphous silicon–germanium multilayers on the atomic scale by ultra-high gravity

Amorphous Si/Ge multilayers containing diffuse interfaces have been prepared, heated in an ultra-centrifuge and subsequent interface structure modifications observed by X-ray reflectivity. The thickness of the Si/Ge and Ge/Si interface zones became asymmetrical owing to various effects occurring on the different atoms parallel to the direction of gravity-induced diffusion. The technique could prove useful for tuning physical (electronic, magnetic or optical) properties of layered structures.     

Chemistry and morphology of β′ precipitates in an aged Mg-Nd-Y-Zr alloy

While the Mg–Y–Nd system is used for industrial applications, the details of the precipitation sequence and exact role of each alloying element during ageing have not been fully quantified. Focusing on WE43, a Mg–Y–Nd alloy containing Zr, the chemistry of β′ precipitates and matrix during isothermal ageing at 250 °C is investigated using atom probe tomography. Precipitate morphologies and compositions are compared with previous electron microscopy observations, and the roles of the alloying elements are discussed.     

Chemical ordering of Co and Ni in a W-(AlCoNi) crystalline approximant related to Al–Co–Ni decagonal quasicrystals studied by atomic resolution energy-dispersive X-ray spectroscopy

A W-(AlCoNi) crystalline approximant, which is closely related to Al–Co–Ni decagonal quasicrystals, in an Al_72.5Co₂₀Ni_7.5 alloy has been studied by atomic resolution energy-dispersive X-ray spectroscopy (EDS), in an instrument attached to a spherical aberration (Cs)-corrected scanning transmission electron microscope. On high-resolution EDS maps of Co and Ni elements, obtained by integrating many sets of EDS data taken from undamaged areas, chemical ordering of Co and Ni is clearly detected. In the structure of the W-(AlCoNi) phase, consisting of arrangements of transition-metal (TM) atoms located at vertices of pentagonal tilings and pentagonal arrangements of mixed sites (MSs) of TM and Al atoms, Co atoms occupy the TM atom positions with the pentagonal tiling and Ni is enriched in part of the pentagonal arrangements of MSs.     

Applicability of Scheil–Gulliver solidification model in real alloy: a case study with Cu-9wt%Ni-6wt%Sn alloy

The present work explores the possibilities of the application of Scheil–Gulliver equation in modelling the solidification of a real alloy. For this study, Cu-9 wt%Ni-6 wt%Sn alloy was chosen which exhibits profuse micro-segregation during solidification, and hence easy to quantify experimentally. Also, this alloy is spinodally strengthened high strength copper alloy and has industrial importance. In this study, thermodynamic assessment using Scheil–Gulliver solidification model was carried out. Subsequently, the assessed result was compared with the experimentally obtained results from energy-dispersive X-ray spectroscopy analysis, and a good agreement was observed between these results. Therefore, it could be concluded that the solidification of this particular alloy system can be modelled using Scheil–Gulliver equation.     

过度担忧和广泛性焦虑障碍与rCBF关系的SPECT脑显像研究

目的：探查过度担忧者和GAD病人的r CBF变化,更好地了解导致病理性焦虑和GAD的神经病理生理学基础。方法：回顾性分析18例过度担忧者和61例GAD病人SPECT脑显像的结果。GAD患者再按病程分为3个亚组。计算各组患者特定脑区r CBF损伤的百分比及损伤的脑区数。结果：12例（66.7%）过度担忧者可见前额叶、基底节、扣带回、颞叶和枕叶r CBF增加（11例）和/或减少（9例）。58例（95.1%）GAD患者可见r CBF减少,主要累及中和下前额叶、中和下颞叶、前扣带、海马旁回、基底节和丘脑。大多数GAD患者累及的主要脑区等于或大于3个。GAD病人的r CBF损伤和病程之间存在一定的相关性。结论：结果支持GAD患者r CBF的变化是一个与担忧和焦虑等心理和情绪改变密切相关的慢性和渐进的过程。GAD的局部脑功能障碍是病理性焦虑产生的先决条件,并出现在局部脑结构异常之前。