多功能数字滑触电桥

阐述了“多功能数字滑触电桥”的设计原理、前面板及实际应用。     

火山岩坡残积土地区暴雨滑坡泥石流的形成机理

暴雨条件诱发的浅层坡残积土质斜坡破坏的机理受控于土体在低有效围压条件下的应力应变特性。1993年11月4～5日,香港大屿山地区特大局部性暴雨导致在120km²范围内产生自然滑坡泥石流800余处,且绝大多数发生于火山岩风化坡残积土地区。本文对火山岩风化坡残积土开展了室内偏压固结不排水剪和偏压固结常剪应力排水剪试验,揭示了该类土的应力应变特性;在此基础上,分析了暴雨滑坡泥石流的形成机理和过程。     

One Pot Synthesis of a Polyisoprene Polyrotaxane and Conversion to a Slide‐Ring Gel

Synthesis of a cyclodextrin (CD) polyrotaxane is achieved for the first time by simultaneous free radical polymerization of isoprene, threading by CD, and stoppering by copolymerization of styrene. This reaction is performed in an eco‐friendly manner in an aqueous medium similar to classical emulsion polymerization. Threaded CD rings of the polyrotaxane are cross‐linked by hexamethylene diisocyanate, leading to highly elastic slide‐ring gels.

     

自由拉氏方法进展

自由拉氏方法是模拟计算二维大变形可压缩流的一种新的尝试。它放弃了传统拉氏方法中网格间固定连接的约束,在计算中每个循环都要检验并且修改节点间的相邻关系,从而能够自动适应变形流动对网格的扭曲。此外我们对自由面和内界面也作了相应的处理。自由拉氏方法被用于流体或流体弹塑性流的计算并且给出了较为满意的结果。     

Development of a Unique, High Precision Linear Motor Integrated Air Slide Table, and Its Application to Laser Beam Writers

This paper reports on the development of a unique, high precision linear motor integrated air slide table for precise positioning and its application to laser beam writers for photo-mask pattern-making. The air slide table takes advantage of the balance between the air bearing’s levitating and magnetic forces. A brushless linear motor and a high resolution linear encoder are integrated into the table. The unique construction of the device results in a very compact package with excellent accuracy. The basic characteristics of the air slide table are evaluated. The device is applied to a laser beam writer, which must be capable of rendering minute and precise patterns for photo-masking equipment. Examples are given including optical devices such as wave guides and Fresnel zone plates which were fabricated and evaluated. Experimental data is given to show that the Fresnel zone plate fabricated here can be used to focus a laser beam to the theoretical limit, just like a standard refractive lens.     

新型牙齿正畸丝材料在唾液中的往复滑动摩擦磨损特性研究

采用小振幅往复滑动摩擦磨损试验机评价了新型牙齿正畸丝材料13Cr24Mn0.44N不锈钢在水和唾液中的摩擦磨损行为,并探讨其磨损机理.结果表明:在唾液中活性成分的作用下,试样表面生成了软质易剪切的表面膜,使得摩擦系数降低,同时部分残留于磨痕中的磨屑在水或唾液介质润滑下承担了类似滚动轴承中"滚珠"的角色,进一步降低了摩擦系数;在2种介质中磨痕深度均随载荷增大而增加,但在唾液中的磨痕深度均小于在水中的磨痕深度,磨损和腐蚀之间呈现"负交互"作用;不锈钢在水中的磨痕呈现微切削和犁沟机制,在唾液中小载荷下的磨痕与水中相似,磨痕呈现微切削和犁沟机制,但在较大载荷时的磨损机制为疲劳脱层并伴有显微切削.     

Enhancement of histological volumes through averaging and their use for the analysis of magnetic resonance images

Magnetic resonance imaging (MRI) of small animals is routinely performed in research centers. But despite its many advantages, MR still suffers from limited spatial resolution which makes the interpretation and quantitative analysis of the images difficult, particularly for small structures of interest within areas of significant heterogeneity. One possibility to address this issue is to complement the MR images with histological data, which requires reconstructing 3D volumes from a series of 2D images. A number of methods have been proposed recently in the literature to address this issue, but deformation or tearing during the slicing process often produces reconstructed volumes with visible artifacts and imperfections. In this paper, we show that a possible solution to this problem is to work with several histological volumes, reconstruct each of these separately and then compute an average. The resulting histological atlas shows structures and substructures more clearly than any individual volume. We also propose an original approach to normalize intensity values across slices, a required preprocessing step when reconstructing histological volumes. We show that the histological atlas we have created can be used to localize structures and substructures, which cannot be seen easily in MR images. We also create an MR atlas that is associated with the histological atlas. We show that using the histological volumes to create the MR atlas is better than using the MR volumes only. Finally, we validate our approach quantitatively on MR image volumes by comparing volumetric measurements obtained manually and obtained automatically with our atlases.     

EVA-enhanced embedding medium for histological analysis of 3D porous scaffold material

When sectioning a 3D porous scaffold made of a soft elastomeric material embedded in paraffin medium, it is not easy to obtain a section because of the different mechanical properties of the paraffin and tissue/scaffold. We describe a new embedding material for histological analysis of various biomaterials that is composed of paraffin and ethylene vinyl acetate (EVA) resin (0, 3, 7, and 13 wt.%). 3D porous poly(l-lactide--caprolactone) (PLCL) and chitosan scaffolds were fabricated to test the sectioning efficiency of the paraffin/EVA embedding material. The new embedding material was characterized by rheological analysis and solvent solubility testing in xylene and n-hexane. The hydrophilicity of the new material was assessed by contact angle measurement and its surface roughness was measured using AFM analysis. The staining efficiency of sections embedded in a paraffin/EVA mixture was determined by eosin staining of the chitosan scaffold and chitosan/collagen hybrid scaffold using a fluorescently labeled collagen. Section roughness decreased with increasing EVA content. The softening temperature of the paraffin/EVA mixture was similar to that of paraffin (50–60 °C by rheometer). The paraffin/EVA mixture dissolved completely in xylene after 30 min at 50 °C, and after 30 min in n-hexane at 60 °C. Therefore, the new embedding medium can be used for histological analysis of various biomaterials and natural tissues.     

Sucrose cryo‐protection facilitates imaging of whole eye sections by MALDI mass spectrometry

Sucrose is used as a cryo‐preservation agent on large mammalian eyes post formalin fixation and is shown to reduce freezing artefacts allowing the collection of 12‐µm thick sections from these large aqueous samples. The suitability of this technique for use in MALDI imaging experiments is demonstrated by the acquisition of the first images of lipid distributions within whole sagittal porcine eye sections. Copyright © 2012 John Wiley & Sons, Ltd.     

A method for quantitative analysis of clump thickness in cervical cytology slides

Knowledge of the spatial distribution and thickness of cytology specimens is critical to the development of digital slide acquisition techniques that minimise both scan times and image file size. In this paper, we evaluate a novel method to achieve this goal utilising an exhaustive high-resolution scan, an over-complete wavelet transform across multi-focal planes and a clump segmentation of all cellular materials on the slide. The method is demonstrated with a quantitative analysis of ten normal, but difficult to scan Pap stained, Thin-prep, cervical cytology slides. We show that with this method the top and bottom of the specimen can be estimated to an accuracy of 1 μm in 88% and 97% of the fields of view respectively. Overall, cellular material can be over 30 μm thick and the distribution of cells is skewed towards the cover-slip (top of the slide). However, the median clump thickness is 10 μm and only 31% of clumps contain more than three nuclei. Therefore, by finding a focal map of the specimen the number of 1 μm spaced focal planes that are required to be scanned to acquire 95% of the in-focus material can be reduced from 25.4 to 21.4 on average. In addition, we show that by considering the thickness of the specimen, an improved focal map can be produced which further reduces the required number of 1 μm spaced focal planes to 18.6. This has the potential to reduce scan times and raw image data by over 25%.